LoRDEC: accurate and efficient long read error correction

Genetic and phenotypic stability of Lacticaseibacillus paracasei DG (DSM 34154) over 10 years of industrial production

The commercialization of a probiotic microorganism requires genetic and phenotypic consistency across production lots. However, the large-scale industrial production of probiotic microbial biomasses over years poses a risk of genetic drift, potentially affecting the probiotic's ability to confer health benefits. This study assessed the stability of Lacticaseibacillus paracasei DG (DSM 34154), a commercial probiotic. Seven isolates from different commercial lots over 10 years, one 8-year-old laboratory subculture, one isolate from human feces, and the DG strain deposited at DSMZ were analyzed. Shotgun and PacBio sequencing were combined to obtain the complete genome of the 10 isolates. Comparative analysis showed that the seven commercial isolates had identical genomes, differing from the DSMZ isolate by one synonymous transition and one non-synonymous transversion. The laboratory subculture strain had two additional mutations. Phenotypic analyses, including antibiotic resistance, carbohydrate fermentation profile, survival to simulated gastrointestinal transit, immunomodulatory capacity, and radical scavenging ability, found no significant differences among isolates. Overall, this study demonstrates the substantial equivalence of L. paracasei DG over 10 years of industrial production, indicating that the current industrial practices help prevent genome alterations that could compromise probiotic performance. Similar studies should be part of continuous monitoring and quality control measures for the probiotic products on the market.IMPORTANCEThe genetic and functional stability of probiotic strains during years of industrial production is essential but has not been clearly demonstrated for many strains. This study shows that careful industrial practices can maintain the genetic integrity and functionality of probiotics. Using advanced genome sequencing and detailed laboratory tests, we confirmed that the probiotic Lacticaseibacillus paracasei DG (DSM 34154) has remained stable over a decade of production, consistently delivering its health-promoting properties. These findings support the quality and reliability of probiotic products, fostering consumer trust and highlighting the importance of continuous monitoring in probiotic manufacturing to sustain quality assurance.

Decoding the complexity of coding and non-coding RNAs across maize anther development at the isoform level

Anther is a key male reproductive organ that is essential for the plant life cycle, from the sporophyte to the gametophyte generation. To explore isoform-level transcriptional landscape of developing anthers in maize (Zea mays L.), we analyzed Iso-Seq data from anthers collected at 10 developmental stages, together with strand-specific RNA-seq, CAGE-seq, and PAS-seq data. Of the 152,026 high-confidence full-length isoforms identified, 68.8% have not been described; these include 22,365 isoforms that originate from previously unannotated loci and 82,167 novel isoforms that originate from annotated protein-coding genes. Using our newly developed strategy to detect dynamic expression patterns of isoforms, we identified 13,899 differentially variable regions (DVRs); surprisingly, 1,275 genes contain more than two DVRs, revealing highly efficient utilization of limited genic regions. We identified 7,876 long non-coding RNAs (lncRNAs) from 4,098 loci, most of which were preferentially expressed during cell differentiation and meiosis. We also detected 371 long-range interactions involving intergenic lncRNAs (lincRNAs); interestingly, 243 were lincRNA-gene ones, and the interacting genes were highly expressed in anthers, suggesting that many potential lncRNA regulators of key genes are required for anther development. This study provides valuable resources and fundamental information for studying the essential transcripts of key genes during anther development.

Transcriptome profiling and alternative splicing analysis of skeletal muscle in Pseudocaranx dentex: insights into slow-twitch and fast-twitch muscle specialization

Alternative splicing (AS) plays a crucial role in regulating muscle type specialization characteristics in mammals but has been rarely explored in teleost. In this study, we combined Iso-Seq and RNA-Seq technologies to profile the transcriptome and AS landscape of slow-twitch muscle (SM) and fast-twitch muscle (FM) in a migratory teleost, Pseudocaranx dentex. We identified 24,096 full-length transcripts and 14,346 isoforms in SM, and 18,483 full-length transcripts and 10,541 isoforms in FM, revealing extensive transcript and isoform diversity. The 3086 differentially expressed transcripts (DETs) were found to contribute to metabolic and contractile differences between SM and FM. Additionally, we detected 5761 AS events in SM and 4543 in FM, with skipped exons (SE) and intron retention (IR) being the predominant AS types. Furthermore, 325 differentially AS genes (DASGs) were found to regulate differences in metabolic processes, organelles organization, cellular component organization, and microtubule-based processes. Importantly, transcripts of tnni2, capzb, neb, and pdlim5 produced by AS with significant expression differences between SM and FM were determined to associate with sarcomere assembly. This study provides the first comprehensive view of transcriptome complexity and splice variants in teleost skeletal muscle and sheds light on the molecular mechanisms underlying muscle type specialization through post-transcriptional regulation.

Pathogenomics Insights into Phytophthora capsici and Phytophthora tropicalis -Sibling Species Causing Black Pepper Foot Rot: Genomic Architecture, Metabolic Pathways, and Effector Diversity

Foot rot disease in black pepper, caused by Phytophthora species, is a major threat to cultivation. Along with the well-known Phytophthora capsici, a newly identified species, Phytophthora tropicalis, has also been implicated. Comparative genome analysis of P. capsici 05-06 from Kerala (80.51 Mb, 626 scaffolds) and P. tropicalis 98-93 from Karnataka (73.54 Mb, 302 scaffolds) revealed similar GC content (∼50.5%) and gene counts (19,639 and 17,716, respectively). Genomic ANI analysis clustered them with P. capsici LT1534-B, suggesting a species complex. Both species contain transposable elements (19.35% and 21.31%), indicating adaptive evolution. Pathway mapping highlights roles in carbohydrate metabolism, carbohydrate-active enzymes (CAZymes: 575 and 566), energy production, effector biosynthesis, and molecular signaling. The presence of unique protein families and shared orthologous genes underscores their pathogenic potential. These findings enhance understanding of their evolution and pathogenicity, aiding in the development of targeted management strategies for black pepper foot rot.

Characterization of the Complete Mitochondrial Genome of Angulyagra polyzonata and Its Phylogenetic Status in Viviparidae

Angulyagra polyzonata is an economically important mollusk in China, but detailed insights into its mitochondrial genome remain scarce. In this study, we sequenced and comprehensively analyzed the structural features and selection pressures of the A. polyzonata mitochondrial genome. The maximum likelihood method and Bayesian phylogenetic inference method were used to construct a phylogenetic tree of A. polyzonata with 21 other species, including gastropods and bivalves. The full-length mitochondrial genome of 17,379 bp was found to include 22 transfer RNA genes, 2 ribosomal RNA genes, and 13 protein-coding genes, exhibiting similarity to the composition and arrangement of mitochondrial genes in other gastropod species. Notably, the Ka/Ks ratios of mitochondrial protein-coding genes (nad5, cox3, nad3, nad2, cox1, cox2, atp8, atp6, nadl, nad6, cob, nad4l, and nad4) were <1, which indicates that the snail genes of the three genera of the family may have been subjected to strong natural selection pressure during the evolutionary process, so that the number of synonymous mutations (ks) in genes was much more than that of nonsynonymous mutations (ka). Comparative genomic analysis indicated that, apart from the absence of trnW and trnQ, the gene composition of A. polyzonata shares a high degree of homology with other members of the conical snail family. Phylogenetic analysis demonstrated that the selected species could be classified into two primary clades in which A. polyzonata clustered with the Viviparidae family. This study bridges the knowledge gap regarding the mitochondrial genome of A. polyzonata and offers valuable insights into the systematic relationships within the Viviparidae family.

Morphogenesis, starvation, and light responses in a mushroom-forming fungus revealed by long-read sequencing and extensive expression profiling

Mushroom-forming fungi (Agaricomycetes) are emerging as pivotal players in several fields of science and industry. Genomic data for Agaricomycetes are accumulating rapidly; however, this is not paralleled by improvements of gene annotations, which leave gene function notoriously poorly understood. We set out to improve our functional understanding of the model mushroom Coprinopsis cinerea by integrating a new, chromosome-level assembly, high-quality gene predictions, and functional information derived from broad gene-expression profiling data. The new annotation includes 5' and 3' untranslated regions (UTRs), polyadenylation sites (PASs), upstream open reading frames (uORFs), splicing isoforms, and microexons, as well as core gene sets corresponding to carbon starvation, light response, and hyphal differentiation. As a result, the genome of C. cinerea has now become the most comprehensively annotated genome among mushroom-forming fungi, which will contribute to multiple rapidly expanding fields, including research on their life history, light and stress responses, as well as multicellular development.

De novo transcriptome assembly and annotation of the semi-wild Gayal (Bos frontalis)

The Gayal (Bos frontalis) is a rare semi-wild Bovine species that inhabits the harsh environments of Indo-China. Although the origins of the Gayal remain largely enigmatic, addressing the lack of comprehensive transcriptomic data is critical for understanding its genetic and molecular characteristics, which are essential for formulating effective conservation and management plans. In this study, an integrated PacBio Iso-seq and RNA-seq analysis was conducted on samples from 10 different organs and tissues of the Gayal, with each being sequenced in triplicate. The samples analyzed included the heart, liver, spleen, lung, kidney, rumen, abomasum, duodenum, ileum, and rectum. This comprehensive analysis resulted in the identification of 30,760 full-length transcripts ranging from 363 bp to 7,157 bp, with transcript information matched to seven commonly used databases. Gene family clustering and phylogenetic analyses encompassed a comprehensive dataset of 9 Bovine species, including the Gayal. Additionally, long non-coding RNAs (lncRNAs) were identified across all sampled tissues, and comprehensive gene expression profiles and differential expression gene analyses were performed. These findings provide a rich repository of genetic information, laying the foundation for comprehensive functional genomics studies and paving the way for deeper insights into the molecular mechanisms of the Gayal, thereby advancing our understanding of its transcriptome architecture and offering crucial data for conservation efforts and practical applications.

Determination of Antimicrobial Resistance Megaplasmid-Like pESI Structures Contributing to the Spread of Salmonella Schwarzengrund in Japan

BACKGROUND/OBJECTIVES

The acquisition of antimicrobial resistance by foodborne pathogens is a serious human health concern. In Japan, combinations of antimicrobial resistance genes in Salmonella from chicken meat were common among several serovars. Therefore, we hypothesized that different S. enterica serovars share a common antimicrobial resistance plasmid.

METHODS

Antimicrobial resistance transfer was tested in S. Infantis and S. Schwarzengrund, the major serovars used as donors. The plasmid structure was determined by subjecting S. Infantis Sal_238 and S. Schwarzengrund Sal_249 to short- and long-read sequencing.

RESULTS

The high homology between pSal_249Sch and pSal_238Inf suggests they have a common ancestor. Because the sequences of pSal_238Inf and pSal_249Sch were highly homologous to pESI (a plasmid for emerging S. Infantis), pSal_238Inf and pSal_249Sch were identified as pESI-like plasmids. S. Schwarzengrund is the third Salmonella serovar to expand its distribution related to pESI-like plasmid acquisition. Core-genome multilocus sequence-type analysis revealed that S. Schwarzengrund isolates with pESI-like plasmids from Japan (core-genome sequence-type [cgST] 167363 and cgST287831), the UK (cgST167363), and the USA (cgST167363, cgST196045, and cgST287831) were closely related; they are also suggested to share a common ancestor. The transfer of antimicrobial resistance was observed in combinations of both serovars. Specifically, the tentative plasmid sequence obtained via short-read sequencing, PCR, and conjugation experiments identified deletions of antimicrobial resistance genes (aadA, sul1, and tetA), class 1 integron, mercury resistance operon, and/or plasmid transfer region in the pESI-like plasmid.

CONCLUSION

These data on the structural diversity of pESI-like plasmids suggest that some time has passed since S. Schwarzengrund acquired them.

The multi-chromosomal structure of mitogenomes provided new insights into the accurate authentication of medicinal Dendrobium species

BACKGROUND

The global prevalence of herbal-based health care rapidly promoted requirements for medicinal plant resources. Accurate classification and identification are crucial to assuring the safety of these herbal sources.

RESULTS

Here, we took Dendrobium (Orchidaceae), a famous horticultural and medicinal plant taxon, as the study focus to establish an effective authentication approach for medicinal plants based on new mtDNA barcodes. We first de novo assembled three complete mitogenomes using Illumina and Nanopore data. These three mitogenomes were 635,454 bp-831,745 bp long with multichromosomal structures. Moreover, the three mitogenomes were compared to the other four published Dendrobium mitogenomes. The results revealed great variations of the structure and repeat contents among these mitogenomes, while gene contents and genomic sequences were relatively conserved. The analysis of mutational hotspots showed eight mitochondrial DNA regions with high sequence variability (> 5%) at the interspecific level, which could provide abundant informatic loci for phylogeny, genetic diversity, and identification analyses. We also newly obtained mitochondrial sequences of 45 individuals from 15 Dendrobium species for authentication analysis. These 15 Dendrobium species were successfully identified by the whole mitogenome sequences and the isoform combination (Mt17 + Mt19) respectively.

CONCLUSIONS

Our findings revealed that mitochondrial isoforms (chromosomes) could be used as super-barcodes for Dendrobium species authentication. The multi-chromosomal structure of mitogenomes provided new insights into the accurate authentication of medical plants.

Full-length transcriptome sequencing of seven tissues of GuShi chickens

Chickens are vital economic poultry and serve as exemplary models for avian research. The incomplete reference genome of chickens and the limited availability of full-length cDNA impede the identification of alternatively spliced transcripts, thereby delaying many fundamental chicken studies. We utilized PacBio Iso-seq technology on various chicken tissues, obtaining 170,162 full-length transcripts through comprehensive transcriptome sequencing and annotation. Of the identified transcripts, 38,925 lncRNAs were predicted and categorized into five models. Our data significantly increases the known number of chickens' lncRNAs and alternatively spliced transcripts are crucial in enhancing current genome annotations. Furthermore, this data will be invaluable for functional studies of other avian species.

Full-length transcriptome analysis of male and female gonads in Japanese Eel (Anguilla japonica)

BACKGROUND

The Japanese eel (Anguilla japonica) holds significant economic value in East Asia, but limitations in understanding its reproductive biology have hindered advancements in artificial breeding techniques. Previous research has primarily focused on conserved sex differentiation genes, offering limited insights into the broader molecular mechanisms driving gonadal development and sexual dimorphism. To address these limitations, this study aims to investigate key genes and pathways involved in gonadal development through a comprehensive transcriptomic analysis of male and female eel gonads.

RESULTS

PacBio Iso-Seq and Illumina RNA-Seq technologies were combined to conduct a full-length transcriptome analysis of male and female Japanese eel gonads at a post-differentiation, pre-maturation stage. A total of 24,661 unigenes were identified in ovaries and 15,023 in testes, along with genomic regulatory elements such as transcription factors, simple sequence repeats, and long non-coding RNAs. Additionally, 1,210 differentially expressed genes were detected. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses revealed significant pathways involved in cell cycle regulation, metabolic processes, apoptosis, and hormone activity. Notably, several reproductive-related genes, including bambi, ccnb1, cdc20, gdf9, prlh, ccdc39, chrebp, tspo, syce3, and ngb, demonstrated significant dimorphic expression in eel gonads.

CONCLUSIONS

This study provides valuable insights into the molecular mechanisms of gonadal differentiation and sexual dimorphism in Japanese eels. The findings expand the genetic resources available for the eel breeding industry and could facilitate the development of improved artificial breeding techniques focused on reproductive development.

Integrated Analysis of Terpenoid Profiles and Full-Length Transcriptome Reveals the Central Pathways of Sesquiterpene Biosynthesis in Atractylodes chinensis (DC.) Koidz

Atractylodes chinensis (DC.) Koidz. is an aromatic and medicinal plant in East Asia. The primary bioactive compounds in this species are sesquiterpenes, particularly β-eudesmol, hinesol, and atractylon. Cultivation techniques require improvement to meet the medicinal demands of this species. In this study, gas chromatography-mass spectrometry analysis of an A. chinensis germplasm showed its essential oil contained various sesquiterpenes, including a high relative ratio of β-eudesmol. Full-length transcriptome profiling of A. chinensis revealed 26 genes related to terpenoid biosynthesis. These genes belonged to 13 gene families, including five in the isopentenyl pyrophosphate synthase gene family and four in the terpene synthase gene family. The functions of the four terpene synthase genes were proposed based on gene expression patterns and phylogenetic relationships: one was thought to encode monoterpene synthase and three to encode sesquiterpene synthase. Based on the results, the central biosynthesis pathways of the major sesquiterpenes in the A. chinensis rhizome were proposed, and three sesquiterpene synthase genes were identified as expressed in the rhizome for the first time. AcHMGR, AcFPPS, and the three sesquiterpene synthase genes were proposed as potential targets for molecular breeding in A. chinensis to enhance its sesquiterpene content.

Chromosome-level Genome Assembly of Korean Long-tailed Chicken and Pangenome of 40 Gallus gallus Assemblies

This study presents the first chromosome-level genome assembly of the Korean long-tailed chicken (KLC), a unique breed of Gallus gallus known as Ginkkoridak. Our assembly achieved a super contig N50 of 5.7 Mbp and a scaffold N50 exceeding 90 Mb, with a genome completeness of 96.3% as assessed by BUSCO using the aves_odb10 set. We also constructed a comprehensive pangenome graph, incorporating 40 Gallus gallus assemblies, including the KLC genome. This graph comprises 87,934,214 nodes, 121,720,974 edges, and a total sequence length of 1,709,850,352 bp. Notably, our KLC assembly contributed 1,919,925 bp of new sequences to the pangenome, underscoring the unique genetic makeup of this breed. Furthermore, in comparison with the pangenome, we identified 36,818 structural variants in KLC, which included 2,529 insertions, 27,743 deletions, and 6,546 of either insertions or deletions shorter than 1 kb. We also successfully identified pan-genome wide non-reference sequences. Our KLC assembly and pangenome graph provide valuable genomic resources for studying G. gallus populations.

The complete mitochondrial genome of Scambus vesicarius Ratzeburg (Hymenoptera: ichneumonidae: pimplinae)

The genomic-level characteristics play a pivotal role as genetic assets for the identification of species and phylogenetic analysis. Here, we sequenced and analyzed the mitochondrial genome of Scambus vesicarius (Ratzeburg), which was first morphologically described in "Die Ichneumonen der Forstinsecten in forstlicher und entomologischer Beziehung." The motivation for this research arises from the necessity to comprehend the genetic composition and evolutionary history of S. vesicarius, a genus of parasitic wasps with potential agricultural significance, which. The circular genome is 26,103bp in length with an overall base composition of 42.02% for A, 43.71% for T, 8.64% for C, and 5.63% for G. The mitochondrial genome of S. vesicarius contained 13 protein-coding genes that initiated by the ATN codon, 22 transfer RNA genes, two ribosomal RNA genes (rRNAs), and a control region (CR). Phylogenetic analyses using Maximum-likelihood methods supported that S. vesicarius is closely related to Pimpla luctuosa, both of which belong to the subfamily Pimplinae, forming a clade that is sister to other subfamilies of Ichneumonidae. This study provides value not only into the genetic diversity and evolutionary history of S. vesicarius at the mitochondrial level but basic research on parasitic wasp biology and applied efforts in biological control.

Repeat and haplotype aware error correction in nanopore sequencing reads with DeChat

Error self-correction is crucial for analyzing long-read sequencing data, but existing methods often struggle with noisy data or are tailored to technologies like PacBio HiFi. There is a gap in methods optimized for Nanopore R10 simplex reads, which typically have error rates below 2%. We introduce DeChat, a novel approach designed specifically for these reads. DeChat enables repeat- and haplotype-aware error correction, leveraging the strengths of both de Bruijn graphs and variant-aware multiple sequence alignment to create a synergistic approach. This approach avoids read overcorrection, ensuring that variants in repeats and haplotypes are preserved while sequencing errors are accurately corrected. Benchmarking on simulated and real datasets shows that DeChat-corrected reads have significantly fewer errors-up to two orders of magnitude lower-compared to other methods, without losing read information. Furthermore, DeChat-corrected reads clearly improves genome assembly and taxonomic classification.

Nanopore Data-Driven T2T Genome Assemblies of Colletotrichum lini Strains

Colletotrichum lini is a pathogenic fungus that infects flax and causes significant yield losses. In this study, we assembled the genomes of four highly virulent C. lini strains using the Oxford Nanopore Technologies (ONT, R10.4.1 flow cells) and Illumina platforms. The performance of two tools developed for telomere-to-telomere (T2T) genome assembly was compared: Verkko and Hifiasm. Prior to the assembly, ONT reads were corrected using the HERRO algorithm. Verkko generated genome assemblies of high completeness but low contiguity, while Hifiasm allowed the generation of T2T assemblies. Despite significantly different genome coverage with ONT data (25-100×), four assemblies of equal contiguity were obtained: 53.6-54.7 Mb, ten core chromosomes, and two or three accessory chromosomes. A comparative analysis of different polishing tools showed that at a certain genome coverage with the corrected ONT data (≥35×), the additional polishing of the assembly did not improve its accuracy, even with the Illumina data. An analysis of the genome structures of the four C. lini strains revealed a high similarity between the core chromosomes. Thus, our approach enabled assembling T2T Colletotrichum genomes only from the ONT data obtained using R10.4.1 flow cells and may be promising for other fungal genera. These assemblies will allow the accurate identification of strain-specific differences at the chromosome level and will aid in the development of effective strategies to protect flax from anthracnose.

Exploring the innate immune system of Urechis unicinctus: Insights from full-length transcriptome analysis

The Echiura worm Urechis unicinctus refers to a common benthic invertebrate found in the intertidal zone of Huanghai as well as Bohai Bay. U. unicinctus is known to contain various physiologically active substances, making it highly valuable in terms of its edibility, medicinal properties, and economic potential. Nonetheless, the limited study on the immune system of U. unicinctus poses difficulties for its aquaculture and artificial reproduction. Marine invertebrates, including shellfish and U. unicinctus, are thought to primarily depend on their innate immune system for disease protection, owing to the severalinnate immune molecules they possess. Herein, we employed PacBio single-molecule real-time (SMRT) sequencing technology to perform the full-length transcriptome analysis of U. unicinctus individuals under five different conditions (room temperature (RT), low temperature (LT), high temperature (HT), without water (DRY), ultraviolet irradiation (UV)). Concequently, we identified 59,371 unigenes that had a 2,779 bp average length, 2,613 long non-coding RNAs (lncRNAs), 59,190 coding sequences (CDSs), 35,166 simple sequence repeats (SSRs), and 1,733 transcription factors (TFs), successfully annotating 90.58 % (53,778) of the unigenes. Subsequently, key factors associated with immune-related processes, such as non-self-recognition, cellular immune defenses, and humoral immune defenses, were searched. Our study also identified pattern recognition receptors (PRRs) that included 17 peptidoglycan recognition proteins (PGRPs), 13 Gram-negative binding proteins (GNBPs), 18 scavenger receptors (SRs), 74 toll-like receptors (TLRs), and 89 C-type lectins (CLTs). Altogether, the high-quality transcriptome obtained data will offer valuable insights for further investigations into U. unicinctus innate immune response, laying the foundation for subsequent molecular biology studies and aquaculture.

Transcriptome sequencing and SSR prediction of Clematis calyx based on SMRT sequencing platform

Clematis is an excellent vertical greening plant for garden viewing vines, with great ornamental and high medicinal value. To obtain transcriptome information and functional gene data for the Clematis calyx, this study utilized three biological replicates of the calyx from each of the three Clematis varieties: 'Henryi', 'Polish spirit', and 'Mme Julia Correvon' Single-molecule real-time sequencing technology was employed for full-length transcriptome sequencing. The study revealed that 21,673,173 non-chimeric sequences were identified through full-length transcriptome sequencing. After clustering, correction, and redundancy removal, 40,465 high-quality, full-length transcripts were obtained. Among these transcripts, there were 15,488 long non-coding RNA (lncRNA), 9,212 simple sequence repeats (SSR) sites, 1,247 transcription factors (TFs), 1,228 alternative splicing events, and 7,189 selectively polyadenylation sites predicted. In addition, 7,442 primer pairs were designed based on the SSR sites, covering 80.76% of the total SSR. 15 primer pairs were randomly selected for amplification, and 73.3% of them were successfully amplified. Transcript annotation results showed that 38,439, 38,094, 26,815, and 33,407 transcripts were annotated to the Nr, KEGG, KOG, and SwissProt databases, respectively. Among these, the KEGG database identified 137 metabolic pathways, including biosynthesis of secondary metabolites, carbon metabolism, and amino acid biosynthesis. 104 and 7 transcripts are involved in the flavonoid and anthocyanin metabolism pathways, respectively. The above results provide initial insights into the transcriptome information and functional characteristics of Clematis calyx. This critical data supports future research on marker primers for the color mechanism of Clematis calyx, the pathways and regulatory mechanisms of flavonoids and other products, as well as specific trait genes.

Transcriptome analysis reveals the regulatory mechanism of myofiber development in male and female black Muscovy duck at different ages

Introduction

Sexual dimorphism in Muscovy ducks results in substantial differences in muscle development potential between males and females, leading to significant variations in growth rates and body weights throughout their development.

Methods

This study aimed to investigate the regulatory mechanisms underlying the differences in muscle development between genders in black Muscovy ducks, we analyzed the phenotypic characteristics and transcriptome profiles of breast muscles in male and female black Muscovy ducks at different developmental stages (postnatal days 28, 42, and 70).

Results

In the analysis of tissue physical morphology, the results showed that females exhibit larger myofiber diameters and lower myofiber densities compared to males at postnatal day 42 (p < 0.05). The difference becomes more pronounced by day 70, however, no significant difference was observed at postnatal day 28. Transcriptome analysis identified a total of 1,118 unique differentially expressed genes (DEGs) across the various comparison groups. In different growth and development stages of black Muscovy ducks, the DEGs like MYLK4, KIT, CD36, ATP2A1 were significantly associated with myofiber hypertrophy, and key pathways such as AMPK signaling pathway, focal adhesion, and ECM-receptor interactions have been found to be closely associated with muscle size and hypertrophy. In the breast muscles of different sexes black Muscovy ducks, the DEGs such as TPM2, HNRNPK, VCP, ATP2A2, and ANKRD1 may be the reason for the difference in breast muscle size between male and female ducks. Furthermore, key pathways, including the cGMP-PKG signaling pathway, calcium signaling pathway, and hypertrophic cardiomyopathy are also involved in regulating the developmental potential differences in muscle between male and female ducks.

Discussion

This study reveals the molecular mechanism regulating the muscle development in male and female black Muscovy ducks at different growth stages, and provides valuable insights into the specific genes responsible for muscle development, laying a theoretical foundation for enhancing the genetic quality of duck meat.

Comparative transcriptome analysis of Cyperus esculentus and C. rotundus with contrasting oil contents in tubers defines genes and regulatory networks involved in oil accumulation

Plant vegetative organs present great potential for lipid storage, with tubers of Cyperus esculentus as a unique example. To investigate the genome and transcriptomic features of C. esculentus and related species, we sequenced and assembled the C. esculentus genome at the contig level. Through a comparative study of high-quality transcriptomes across 36 tissues from high-oil and intermediate-oil C. esculentus and low-oil Cyperus rotundus, we identified potential genes and regulatory networks related to tuber oil accumulation. First, we identified tuber-specific genes in two C. esculentus cultivars. Second, genes involved in fatty acid (FA) biosynthesis, triacylglycerol synthesis, and TAG packaging presented increased activity in the later stages of tuber development. Notably, tubers with high oil contents presented higher levels of these genes than those with intermediate oil contents did, whereas tubers with low oil contents presented minimal gene expression. Notably, a large fragment of the FA biosynthesis rate-limiting enzyme-encoding gene BCCP1 was missing from the C. rotundus transcript, which might be responsible for blocking FA biosynthesis in its tubers. WGCNA pinpointed a gene module linked to tuber oil accumulation, with a coexpression network involving the transcription factors WRI1, MYB4, and bHLH68. The ethylene-related genes in this module suggest a role for ethylene signaling in oil accumulation, which is supported by the finding that ethylene (ETH) treatment increases the oil content in C. esculentus tubers. This study identified potential genes and networks associated with tuber oil accumulation in C. esculentus, highlighting the role of specific genes, transcription factors, and ethylene signaling in this process.

Full-length transcriptome assembly of black amur bream (Megalobrama terminalis) as a reference resource

BACKGROUND

The genus Megalobrama holds significant economic value in China, with M. terminalis (Black Amur bream) ranking second in production within this group. However, lacking comprehensive genomic and transcriptomic data has impeded research progress. This study aims to fill this gap through an extensive transcriptomic analysis of M. terminalis.

METHODS AND RESULTS

We utilized PacBio Isoform Sequencing to generate 558,998 subreads, totaling 45.52 Gb, which yielded 22,141 transcripts after rigorous filtering and clustering. Complementary Illumina short-read sequencing corrected 967,114 errors across these transcripts. Our analysis identified 12,426 non-redundant isoforms, with 11,872 annotated in various databases. Functional annotation indicated 11,841 isoforms matched entries in the NCBI non-redundant protein sequences database. Gene Ontology analysis categorized 10,593 isoforms, revealing strong associations with cellular processes and binding functions. Additionally, 8203 isoforms were mapped to pathways in the Kyoto Encyclopedia of Genes and Genomes, highlighting significant involvement in immune system processes and complement cascades. We notably identified key immune molecules such as alpha-2-macroglobulin and complement component 3, each with multiple isoforms, underscoring their potential roles in the immune response. Our analysis also uncovered 853 alternative splicing events, predominantly involving retained introns, along with 672 transcription factors and 426 long non-coding RNAs.

CONCLUSIONS

The high-quality reference transcriptome generated in this study provides a valuable resource for comparative genomic studies within the Megalobrama genus, supporting future research to enhance aquaculture stocks.

Mitochondrial genome insights into the spatio-temporal distribution and genetic diversity of Dendrobium hancockii Rolfe (Orchidaceae)

Introduction

With its distinctive evolutionary rate and inheritance patterns separate from the nuclear genome, mitochondrial genome analysis has become a prominent focus of current research. Dendrobium hancockii Rolfe, a species of orchid with both medicinal and horticultural value, will benefit from the application of the fully assembled and annotated mitochondrial genome. This will aid in elucidating its phylogenetic relationships, comparative genomics, and population genetic diversity.

Methods

Based on sequencing results from Illumina combined with PacBio and Nanopore, the mitochondrial genome map of D. hancockii was constructed. Comparative analysis was conducted from the perspectives of phylogeny across multiple species, selection pressure on protein-coding genes, and homologous segments. The population diversity of D. hancockii was analyzed using single nucleotide polymorphism (SNP) data from the mitochondrial genome and single-copy nuclear genes.

Results and discussion

This research constructed a circular mitochondrial map for D. hancockii, spanning 523,952 bp, containing 40 unique protein-coding genes, 37 transfer RNA genes, and 4 ribosomal RNA genes. Comparative analysis of mitochondrial genes from 26 land plants revealed a conserved gene cluster, "rpl16-ccmFn-rps3-rps19," particularly within the Dendrobium genus. The mitochondrial genome of D. hancockii exhibits a lower point mutation rate but significant structural variation. Analysis of 103 resequencing samples identified 19,101 SNP sites, dividing D. hancockii into two major groups with limited gene flow between them, as supported by population diversity, genetic structure analysis, principal component analysis, and phylogenetic trees. The geographical distribution and genetic differentiation of D. hancockii into two major groups suggest a clear phytogeographical division, likely driven by ancient geological or climatic events. The close alignment of mitochondrial data with nuclear gene data highlights the potential of the mitochondrial genome for future studies on genetic evolution in this species.

HyLight: Strain aware assembly of low coverage metagenomes

Different strains of identical species can vary substantially in terms of their spectrum of biomedically relevant phenotypes. Reconstructing the genomes of microbial communities at the level of their strains poses significant challenges, because sequencing errors can obscure strain-specific variants. Next-generation sequencing (NGS) reads are too short to resolve complex genomic regions. Third-generation sequencing (TGS) reads, although longer, are prone to higher error rates or substantially more expensive. Limiting TGS coverage to reduce costs compromises the accuracy of the assemblies. This explains why prior approaches agree on losses in strain awareness, accuracy, tendentially excessive costs, or combinations thereof. We introduce HyLight, a metagenome assembly approach that addresses these challenges by implementing the complementary strengths of TGS and NGS data. HyLight employs strain-resolved overlap graphs (OG) to accurately reconstruct individual strains within microbial communities. Our experiments demonstrate that HyLight produces strain-aware and contiguous assemblies at minimal error content, while significantly reducing costs because utilizing low-coverage TGS data. HyLight achieves an average improvement of 19.05% in preserving strain identity and demonstrates near-complete strain awareness across diverse datasets. In summary, HyLight offers considerable advances in metagenome assembly, insofar as it delivers significantly enhanced strain awareness, contiguity, and accuracy without the typical compromises observed in existing approaches.

Chromosome-level genome assembly of Huai pig (Sus scrofa)

Although advances in long-read sequencing technology and genome assembly techniques have facilitated the study of genomes, little is known about the genomes of unique Chinese indigenous breeds, including the Huai pig. Huai pig is an ancient domestic pig breed and is well-documented for its redder meat color and high forage tolerance compared to European domestic pigs. In the present study, we sequenced and assembled the Huai pig genome using PacBio, Hi-C, and Illumina sequencing technologies. The final highly contiguous chromosome-level Huai pig genome spans 2.53 Gb with a scaffold N50 of 138.92 Mb. The Benchmarking Universal Single-Copy Orthologs (BUSCO) completeness score for the assembled genome was 95.33%. Remarkably, 23,389 protein-coding genes were annotated in the Huai-pig genome, along with 45.87% repetitive sequences. Overall, this study provided new foundational resources for future genetic research on Chinese domestic pigs.

Evolution and post-transcriptional regulation insights of m6A writers, erasers, and readers in plant epitranscriptome

As a dynamic and reversible post-transcriptional marker, N6-methyladenosine (m6A) plays an important role in the regulation of biological functions, which are mediated by m6A pathway components including writers (MT-A70, FIP37, VIR and HAKAI family), erasers (ALKBH family) and readers (YTH family). There is an urgent need for a comprehensive analysis of m6A pathway components across species at evolutionary levels. In this study, we identified 4062 m6A pathway components from 154 plant species including green algae, utilizing large-scale phylogenetic to explore their origin and evolution. We discovered that the copy number of writers was conserved among different plant lineages, with notable expansions in the ALKBH and YTH families. Synteny network analysis revealed conserved genomic contexts and lineage-specific transpositions. Furthermore, we used Direct RNA Sequencing (DRS) to reveal the Poly(A) length (PAL) and m6A ratio profiles in six angiosperms species, with a particular focus on the m6A pathway components. The ECT1/2-Poeaece4 sub-branches (YTH family) with unique genomic contexts exhibited significantly higher expression level than genes of other ECT1/2 poeaece sub-branches (ECT1/2-Poeaece1-3), accompanied by lower m6A modification and PAL. Besides, conserved m6A sites distributed in CDS and 3'UTR were detected in the ECT1/2-Poaceae4, and the dual-luciferase assay further demonstrated that these conserved m6A sites in the 3'UTR negatively regulated the expression of Firefly luciferase (LUC) gene. Finally, we developed transcription factor regulatory networks for m6A pathway components, using yeast one-hybrid assay demonstrated that PheBPC1 could interact with the PheECT1/2-5 promoter. Overall, this study presents a comprehensive evolutionary and functional analysis of m6A pathway components and their modifications in plants, providing a valuable resource for future functional analysis in this field.

De novo Whole-Genome Assembly of the 10-Gigabase Fokienia Hodginsii Genome to Reveal Differential Epigenetic Events Between Callus and Xylem

Fokienia hodginsii (F. hodginsii), belonging to the genus Fokienia of the Cupressaceae. F. hodginsii has significant application value due to its wood properties and great research value in evolutionary studies as a gymnosperm. However, the genome of F. hodginsii remains unknown due to the large size of gymnosperms genome. Pacific Bioscience sequencing, Hi-C mapping, whole-genome Bisulfite Sequencing (BS-Seq), long-read isoform sequencing (Iso-Seq), direct RNA sequencing (DRS), quantitative proteomics, and metabonomics analysis are employed to facilitate genome assembly, gene annotation, and investigation into epigenetic mechanisms. In this study, the 10G F. hodginsii genome is assembled into 11 chromosomes. Furthermore, 50 521 protein-coding genes are annotated and determined that 65% of F. hodginsii genome comprises repetitive sequences. It is discovered that transposable element (TE)-including introns is associated with higher expression. The DNA methylome of F. hodginsii reveals that xylem has a higher DNA methylation level compared to callus. Moreover, DRS reveals the significant alterations in RNA full-length ratio, which potentially associated with poly(A) length (PAL) and alternative polyadenylation (APA). Finally, the morphology measurement and metabonomics analysis revealed the difference of 14 cultivars. In summary, the genomes and epigenetics datasets provide a molecular basis for callus formation in the gymnosperm family.

Integration of full-length Iso-Seq, Illumina RNA-Seq, and flavor testing reveals potential differences in ripened fruits between two Passiflora edulis cultivars

Background

Passion fruit (Passiflora edulis) is loved for its delicious flavor and nutritious juice. Although studies have delved into the cultivation and enhancement of passion fruit varieties, the underlying factors contributing to the fruit's appealing aroma remain unclear.

Methods

This study analyzed the full-length transcriptomes of two passion fruit cultivars with different flavor profiles: "Tainong 1" (TN1), known for its superior fruit flavor, and "Guihan 1" (GH1), noted for its strong environmental resilience but lackluster taste. Utilizing PacBio Iso-Seq and Illumina RNA-Seq technologies, we discovered terpene synthase (TPS) genes implicated in fruit ripening that may help explain the flavor disparities.

Results

We generated 15,913 isoforms, with N50 lengths of 1,500 and 1,648 bp, and mean lengths of 1,319 and 1,463 bp for TN1 and GH1, respectively. Transcript and isoform lengths ranged from a maximum of 7,779 bp to a minimum of 200 and 209 bp. We identified 14,822 putative coding DNA sequences (CDSs) averaging 1,063 bp, classified 1,007 transcription factors (TFs) into 84 families. Additionally, differential expression analysis of ripening fruit from both cultivars revealed 314 upregulated and 43 downregulated unigenes in TN1 compared to GH1. The top 10 significantly enriched Gene Ontology (GO) terms for the differentially expressed genes (DEGs) indicated that TN1's upregulated genes were primarily involved in nutrient transport, whereas GH1's up-regulated genes were associated with resistance mechanisms. Meanwhile, 17 PeTPS genes were identified in P. edulis and 13 of them were TPS-b members. A comparative analysis when compared PeTPS with AtTPS highlighted an expansion of the PeTPS-b subfamily in P. edulis, suggesting a role in its fruit flavor profile.

Conclusion

Our findings explain that the formation of fruit flavor is attributed to the upregulation of essential genes in synthetic pathway, in particular the expansion of TPS-b subfamily involved in terpenoid synthesis. This finding will also provide a foundational genetic basis for understanding the nuanced flavor differences in this species.

Genome assembly in the telomere-to-telomere era

Genome sequences largely determine the biology and encode the history of an organism, and de novo assembly - the process of reconstructing the genome sequence of an organism from sequencing reads - has been a central problem in bioinformatics for four decades. Until recently, genomes were typically assembled into fragments of a few megabases at best, but now technological advances in long-read sequencing enable the near-complete assembly of each chromosome - also known as telomere-to-telomere assembly - for many organisms. Here, we review recent progress on assembly algorithms and protocols, with a focus on how to derive near-telomere-to-telomere assemblies. We also discuss the additional developments that will be required to resolve remaining assembly gaps and to assemble non-diploid genomes.

Transcriptome data for an ancient 'living-fossil' mollusc, Entemnotrochus rumphii

The Pleurotomarioidea, commonly referred to as slit shells, constitute one of the most ancient and enduring lineages within the phylum Mollusca, with its fossil record tracing back to the Upper Cambrian epoch. Its rareness and evolutionary antiquity surpass even that of the nautilus. In this study, we conducted the first transcriptome sequencing and analyses of Entemnotrochus rumphii (Schepman, 1879), a representative species of Pleurotomarioidea. Full-length transcriptome sequencing of E. rumphii was performed using the PacBio Sequel II platform with SMRT technology. A total of 64.38 gigabytes of data and 964,550 polymerase reads were generated, resulting in 28,068,998 subreads after data filtering. After de-duplication, correction, and clustering, we identified 19,273 genes. Additionally, next-generation sequencing was performed on 11 tissues of E. rumphii. This investigation provides a detailed portrayal and analytical scrutiny of its transcriptomic landscape.

The Chrysosplenium sinicum genome provides insights into adaptive evolution of shade plants

Chrysosplenium sinicum, a traditional Tibetan medicinal plant, can successfully thrive in low-light environments for long periods of time. To investigate the adaptive evolution of shade plants in low-light environments, we generated a chromosome-scale genome assembly (~320 Mb) for C. sinicum by combining PacBio sequencing and Hi-C technologies. Based on our results, gene families related to photosynthesis and cell respiration greatly expanded and evolved in C. sinicum genome due to intracellular DNA transfer from organelle genome to nuclear genome. Under positive selective pressure, adaptive evolution of light-harvesting complex II (LHCII) component protein CsLhcb1s resulted in the expansion of threonine residues at the phosphorylation site of STN7 kinase, potentially establishing a crucial genomic foundation for enhancing C. sinicum's adaptability in low-light environments. Through transcriptome and metabolome analysis, we identified chrysosplenol and chrysosplenoside as predominant flavonoid metabolites of C. sinicum and predicted their synthesis pathways. In addition, analysis of alternative splicing (AS) revealed that AS events help regulate state transition and flavonoid biosynthesis. The present study provides new insights into the genomes of shade plants exposed to low-light conditions and adaptive evolution of these genomes; in addition, the results improve our current knowledge on the biosynthetic and regulatory processes of chrysosplenol and chrysosplenoside.

Identification of pine wood nematode (Bursaphelenchus xylophilus) loading response genes in Japanese pine sawyer (Monochamus alternatus) through comparative genomics and transcriptomics

BACKGROUND

Pine wood nematode (PWN; Bursaphelenchus xylophilus) is the causative agent of pine wilt disease (PWD), which is considered the most dangerous biohazard to conifer trees globally. The transmission of PWN relies on insect vectors, particularly the Japanese pine sawyer (JPS; Monochamus alternatus). However, the molecular mechanism underlying PWN-JPS assembly remains largely unknown.

RESULTS

Here, we found that both geographical and gender could significantly affect the PCA (PWN carrying amount) of JPS; thus, JPS transcriptomes from diverse locations and genders were explored regard to PWN loading. Due to the shortage of genomes, we developed a full-length reference transcriptome for analyzing next-generation sequencing data. A comparative genomic study was performed, and 11 248 potential PWN-carrying associate genes (β) were nominated in JPS by using the reported genomes of PWN and non-PWN carrier insect species. Then, 151 differentially expressed transcripts (DETs), 28 of them overlapped with β, correlated with the PCA of JPS were nominated by RNA-Seq, and found that fatty acid β-oxidation might be the key factor that affected the PCA of JPS. Furthermore, JPS fatty acid β-oxidation rates were experimentally decreased using the inhibitor Etomoxir, leading to an increased PCA of JPS. Meanwhile, silencing MaCPT1 in JPS by RNA interference led to a decreased fatty acid β-oxidation rate and increased PCA of JPS.

CONCLUSIONS

In conclusion, MaCPT1 was able to decrease the PWN-JPS assembly formation through the fatty acid β-oxidation of JPS. These results provide new insights for exploring the impact of PWN invasion on JPS. © 2024 Society of Chemical Industry.

SMRT sequencing of a full-length transcriptome reveals cold induced alternative splicing in Vitis amurensis root

Alternative splicing enhances diversity at the transcriptional and protein levels that widely involved in plant response to biotic and abiotic stresses. V. amurensis is an extremely cold-tolerant wild grape variety, however, studies on alternative splicing (AS) in amur grape at low temperatures are currently poorly understood. In this study, we analyzed full-length transcriptome and RNA seq data at 0, 2, and 24 h after cold stress in V. amurensis roots. Following quality control and correction, 221,170 high-quality full-length non-concatemer (FLNC) reads were identified. A total of 16,181 loci and 30,733 isoforms were identified. These included 22,868 novel isoforms from annotated genes and 2815 isoforms from 2389 novel genes. Among the distinguished novel isoforms, 673 Long non-coding RNAs (LncRNAs) and 18,164 novel isoforms open reading frame (ORF) region were found. A total of 2958 genes produced 8797 AS events, of which 189 genes were involved in the low-temperature response. Twelve transcription factors show AS during cold treatment and VaMYB108 was selected for initial exploration. Two transcripts, Chr05.63.1 (VaMYB108short) and Chr05.63.2 (VaMYB108normal) of VaMYB108, display up-regulated expression after cold treatment in amur grape roots and are both localized in the nucleus. Only VaMYB108normal exhibits transcriptional activation activity. Overexpression of either VaMYB108short or VaMYB108normal in grape roots leads to increased expression of the other transcript and both increased chilling resistance of amur grape roots. The results improve and supplement the genome annotations and provide insights for further investigation into AS mechanisms during cold stress in V. amurensis.

DeepCorr: a novel error correction method for 3GS long reads based on deep learning

Long reads generated by third-generation sequencing (3GS) technologies are involved in many biological analyses and play a vital role due to their ultra-long read length. However, the high error rate affects the downstream process. DeepCorr, a novel error correction algorithm for data from both PacBio and ONT platforms based on deep learning is proposed. The core algorithm adopts a recurrent neural network to capture the long-term dependencies in the long reads to convert the problem of long-read error correction to a multi-classification task. It first aligns the high-precision short reads to long reads to generate the corresponding feature vectors and labels, then feeds these vectors to the neural network, and finally trains the model for prediction and error correction. DeepCorr produces untrimmed corrected long reads and improves the alignment identity while maintaining the length advantage. It can capture and make full use of the dependencies to polish those bases that are not aligned by any short read. DeepCorr achieves better performance than that of the state-of-the-art error correction methods on real-world PacBio and ONT benchmark data sets and consumes fewer computing resources. It is a comprehensive deep learning-based tool that enables one to correct long reads accurately.

Differences in alternative splicing events in the adaptive strategies of two Daphnia galeata genotypes induced by fish kairomones

BACKGROUND

Daphnia galeata is a suitable model organism for investigating predator-induced defense. Genes and pathways exhibiting differential expression between fish kairomone-treated and untreated groups in D. galeata have been identified. However, understanding of the significance of alternative splicing, a crucial process of the regulation of gene expression in eukaryotes, to this mechanism remains limited. This study measured life-history traits and conducted short-read RNA sequencing and long-read isoform sequencing of two Korean D. galeata genotypes (KB1 and KE2) to uncover the genetic mechanism underlying their phenotypic plasticity under predation stress.

RESULTS

KB1 exhibited strategies to enhance fertility and decrease body length when exposed to fish kairomones, while KE2 deployed an adaptive strategy to increase body length. Full-length transcriptomes from KB1 and KE2 yielded 65,736 and 57,437 transcripts, respectively, of which 32 differentially expressed transcripts (DETs) were shared under predation stress across both genotypes. Prominent DETs common to both genotypes were related to energy metabolism and the immune system. Additionally, differential alternative splicing (DAS) events were detected in both genotypes in response to fish kairomones. DAS genes shared between both genotypes may indicate their significant role in the post-transcriptional stress response to fish predation. Calpain-3, involved in digestion and nutrient absorption, was identified as a DAS gene in both genotypes when exposed to fish kairomones. In addition, the gene encoding thymosin beta, which is related to growth, was found to be a statistically significant DAS only in KB1, while that encoding ultraspiracle protein, also associated with growth, was only identified in KE2. Moreover, transcripts encoding proteins such as EGF-like domain-containing protein, vitellogenin fused with superoxide dismutase, and others were identified overlapping between DAS events and DETs and potentially elucidating their association with the observed phenotypic variation in each genotype.

CONCLUSIONS

Our findings highlight the crucial role of alternative splicing in modulating transcriptome landscape under predation stress in D. galeata, emphasizing the requirement for integrating gene expression and splicing analyses in evolutionary adaptation studies.

Identification and characterization of olfactory gene families in Macrobrachium rosenbergii based on full-length transcripts and genome sequences

The olfactory gene families include odorant binding proteins (OBPs), chemosensory proteins (CSPs), olfactory receptors (ORs), ionotropic receptors (IRs) and gustatory receptors (GRs). To investigate the molecular function of olfactory perception in Macrobrachium rosenbergii, we integrated the full-length transcripts and whole-genome sequences to identify the olfactory gene families. In this study, a total of 38,955 full-length transcripts with an N50 length of 3383 bp were obtained through PacBio SMRT sequencing. Through the annotation of full-length transcripts and whole-genome sequences, several olfactory gene families were identified, including 18 MrORs, 16 MrIRs, 151 MrIGluRs (ionotropic glutamate receptors), 2 MrVIGluRs (variant ionotropic glutamate receptors) and 3 MrCRs (chemosensory receptors). Notably, the CRs were first identified in prawns and shrimps. Additionally, the olfactory gene families in M. nipponense were identified, comprising 4 MnORs, 21 MnIRs, 79 MnIGluRs, 5 MnVIGluRs, 1 MnGR and 1 MnOBP, using the available whole-genome sequences. Meanwhile, the external morphology of the chemical sensory organs of M. rosenbergii was explored, and the presence of plumose setae (PS), hard thorn setae (HTS), bamboo shoot setae (BSS), soft thorn setae (STS) and aesthetascs (AE) on the antennules, HTS and BSS on the second antennae, and PS on the pereiopods were observed by scanning electron microscope. This study provides valuable insights for future functional studies into the olfactory perception of crustaceans and establishes a theoretical basis for molecular design breeding in M. rosenbergii.

Unraveling the molecular landscape of breast muscle development in domestic Yuzhong pigeons and European meat pigeon: Insights from Iso-seq and RNA-seq analysis

The mechanisms governing gene regulation in domestic Yuzhong pigeon breast muscle development remain largely elusive. Here, we conducted a comparative analysis using Iso-seq and RNA-seq data from domestic Yuzhong pigeons and European meat pigeons to uncover signaling pathways and genes involved in breast muscle development. The Iso-seq data from domestic Yuzhong pigeons yielded 131,377,075 subreads, resulting in 16,587 non-redundant high-quality full-length transcripts post-correction. Furthermore, utilizing pfam, CPC, PLEK, and CPAT, we predicted 5575, 4973, 2333, and 4336 lncRNAs, respectively. Notably, several genes potentially implicated in breast muscle development were identified, including tropomyosin beta chain, myosin regulatory light chain 2, and myosin binding protein C. KEGG enrichment analysis revealed critical signaling pathways in breast muscle development, spanning carbon metabolism, biosynthesis of amino acids, glycolysis/gluconeogenesis, estrogen signaling, PI3K-AKT signaling, protein processing in the endoplasmic reticulum, oxidative phosphorylation, pentose phosphate pathway, fructose and mannose metabolism, and tight junctions. These findings offer insights into the biological processes driving breast muscle development in domestic Yuzhong pigeon, contributing to our understanding of this complex phenomenon.

NmTHC: a hybrid error correction method based on a generative neural machine translation model with transfer learning

BACKGROUNDS

The single-pass long reads generated by third-generation sequencing technology exhibit a higher error rate. However, the circular consensus sequencing (CCS) produces shorter reads. Thus, it is effective to manage the error rate of long reads algorithmically with the help of the homologous high-precision and low-cost short reads from the Next Generation Sequencing (NGS) technology.

METHODS

In this work, a hybrid error correction method (NmTHC) based on a generative neural machine translation model is proposed to automatically capture discrepancies within the aligned regions of long reads and short reads, as well as the contextual relationships within the long reads themselves for error correction. Akin to natural language sequences, the long read can be regarded as a special "genetic language" and be processed with the idea of generative neural networks. The algorithm builds a sequence-to-sequence(seq2seq) framework with Recurrent Neural Network (RNN) as the core layer. The before and post-corrected long reads are regarded as the sentences in the source and target language of translation, and the alignment information of long reads with short reads is used to create the special corpus for training. The well-trained model can be used to predict the corrected long read.

RESULTS

NmTHC outperforms the latest mainstream hybrid error correction methods on real-world datasets from two mainstream platforms, including PacBio and Nanopore. Our experimental evaluation results demonstrate that NmTHC can align more bases with the reference genome without any segmenting in the six benchmark datasets, proving that it enhances alignment identity without sacrificing any length advantages of long reads.

CONCLUSION

Consequently, NmTHC reasonably adopts the generative Neural Machine Translation (NMT) model to transform hybrid error correction tasks into machine translation problems and provides a novel perspective for solving long-read error correction problems with the ideas of Natural Language Processing (NLP). More remarkably, the proposed methodology is sequencing-technology-independent and can produce more precise reads.

Chromosome-level genome assemblies of 2 hemichordates provide new insights into deuterostome origin and chromosome evolution

Deuterostomes are a monophyletic group of animals that includes Hemichordata, Echinodermata (together called Ambulacraria), and Chordata. The diversity of deuterostome body plans has made it challenging to reconstruct their ancestral condition and to decipher the genetic changes that drove the diversification of deuterostome lineages. Here, we generate chromosome-level genome assemblies of 2 hemichordate species, Ptychodera flava and Schizocardium californicum, and use comparative genomic approaches to infer the chromosomal architecture of the deuterostome common ancestor and delineate lineage-specific chromosomal modifications. We show that hemichordate chromosomes (1N = 23) exhibit remarkable chromosome-scale macrosynteny when compared to other deuterostomes and can be derived from 24 deuterostome ancestral linkage groups (ALGs). These deuterostome ALGs in turn match previously inferred bilaterian ALGs, consistent with a relatively short transition from the last common bilaterian ancestor to the origin of deuterostomes. Based on this deuterostome ALG complement, we deduced chromosomal rearrangement events that occurred in different lineages. For example, a fusion-with-mixing event produced an Ambulacraria-specific ALG that subsequently split into 2 chromosomes in extant hemichordates, while this homologous ALG further fused with another chromosome in sea urchins. Orthologous genes distributed in these rearranged chromosomes are enriched for functions in various developmental processes. We found that the deeply conserved Hox clusters are located in highly rearranged chromosomes and that maintenance of the clusters are likely due to lower densities of transposable elements within the clusters. We also provide evidence that the deuterostome-specific pharyngeal gene cluster was established via the combination of 3 pre-assembled microsyntenic blocks. We suggest that since chromosomal rearrangement events and formation of new gene clusters may change the regulatory controls of developmental genes, these events may have contributed to the evolution of diverse body plans among deuterostomes.

Carbapenem and colistin-resistant hypervirulent Klebsiella pneumoniae: An emerging threat transcending the egyptian food chain

BACKGROUND

Carbapenem-resistant Klebsiella pneumoniae (CRKP) is a great public health problem and is associated with many disease outbreaks and high mortality rates. Alarmingly, K. pneumoniae has been isolated from food in several recent studies. This study aimed to investigate the prevalence and characteristics of CRKP in food samples from Egypt.

METHODS

A total of 311 food samples (including 116 minced meat, 92 chicken meat, 75 diced meat, and 28 mutton) were collected from local markets in Egypt and were screened for CRKP with the determination of their antimicrobial resistance profiles. The whole genome sequence was done for 23 CRKP isolates to clarify the relationship between CRKP from food and human cases in Egypt using the SNP core genome. The conjugation probability of the blaNDM-5 harboring plasmid was identified using oriTfinder RESULTS: CRKP was isolated from 11% (35/311) of the samples, with 45.71% (16/35) of them showing resistance to colistin, one of the last-resort options for treating CRKP-mediated infections. In addition to the carbapenem and colistin resistance, the CRKP isolates frequently exhibited resistance to multiple antimicrobials including β-lactams, fluoroquinolones, aminoglycosides, tetracyclines, and chloramphenicol. In addition, most of the CRKP were potentially hypervirulent K. pneumoniae (HvKP) identified as phylogroup Kp1 and of high-risk groups as detected in STs reported in many human outbreaks globally, such as ST383 and ST147. The core-genome phylogeny showed similarities between the isolates from this study and those previously isolated from clinical human samples in Egypt. In addition, analysis of the plasmid on which blaNDM is encoded revealed that several antimicrobial resistance genes such as blaOXA-9, blaCTX-M-15, aac(6')-Ib, qnrS1, and several virulence genes are encoded on the same plasmid.

CONCLUSIONS

This study is significant for food safety and public health and is important to further identify the change in the epidemiology of CRKP infections, especially the consumption of contaminated food products.

Multiple strategies, including 6mA methylation, affecting plant alternative splicing in allopolyploid peanut

Alternative splicing (AS), an important post-transcriptional regulation mechanism in eukaryotes, can significantly increase transcript diversity and contribute to gene expression regulation and many other complicated developmental processes. While plant gene AS events are well described, few studies have investigated the comprehensive regulation machinery of plant AS. Here, we use multi-omics to analyse peanut AS events. Using long-read isoform sequencing, 146 464 full-length non-chimeric transcripts were obtained, resulting in annotation corrections for 1782 genes and the identification of 4653 new loci. Using Iso-Seq RNA sequences, 271 776 unique splice junctions were identified, 82.49% of which were supported by transcriptome data. We characterized 50 977 polyadenylation sites for 23 262 genes, 12 369 of which had alternative polyadenylation sites. AS allows differential regulation of the same gene by miRNAs at the isoform level coupled with polyadenylation. In addition, we identified many long non-coding RNAs and fusion transcripts. There is a suppressed effect of 6mA on AS and gene expression. By analysis of chromatin structures, the genes located in the boundaries of topologically associated domains, proximal chromosomal telomere regions, inter- or intra-chromosomal loops were found to have more unique splice isoforms, higher expression, lower 6mA and more transposable elements (TEs) in their gene bodies than the other genes, indicating that chromatin interaction, 6mA and TEs play important roles in AS and gene expression. These results greatly refine the peanut genome annotation and contribute to the study of gene expression and regulation in peanuts. This work also showed AS is associated with multiple strategies for gene regulation.

Pan-transcriptomic analysis reveals alternative splicing control of cold tolerance in rice

Plants have evolved complex mechanisms to adapt to harsh environmental conditions. Rice (Oryza sativa) is a staple food crop that is sensitive to low temperatures. However, its cold stress responses remain poorly understood, thus limiting possibilities for crop engineering to achieve greater cold tolerance. In this study, we constructed a rice pan-transcriptome and characterized its transcriptional regulatory landscape in response to cold stress. We performed Iso-Seq and RNA-Seq of 11 rice cultivars subjected to a time-course cold treatment. Our analyses revealed that alternative splicing-regulated gene expression plays a significant role in the cold stress response. Moreover, we identified CATALASE C (OsCATC) and Os03g0701200 as candidate genes for engineering enhanced cold tolerance. Importantly, we uncovered central roles for the 2 serine-arginine-rich proteins OsRS33 and OsRS2Z38 in cold tolerance. Our analysis of cold tolerance and resequencing data from a diverse collection of 165 rice cultivars suggested that OsRS2Z38 may be a key selection gene in japonica domestication for cold adaptation, associated with the adaptive evolution of rice. This study systematically investigated the distribution, dynamic changes, and regulatory mechanisms of alternative splicing in rice under cold stress. Overall, our work generates a rich resource with broad implications for understanding the genetic basis of cold response mechanisms in plants.

Combined full-length transcriptomic and metabolomic analysis reveals the molecular mechanisms underlying nutrients and taste components development in Primulina juliae

BACKGROUND

Primulina juliae has recently emerged as a novel functional vegetable, boasting a significant biomass and high calcium content. Various breeding strategies have been employed to the domestication of P. juliae. However, the absence of genome and transcriptome information has hindered the research of mechanisms governing the taste and nutrients in this plant. In this study, we conducted a comprehensive analysis, combining the full-length transcriptomics and metabolomics, to unveil the molecular mechanisms responsible for the development of nutrients and taste components in P. juliae.

RESULTS

We obtain a high-quality reference transcriptome of P. juliae by combing the PacBio Iso-seq and Illumina sequencing technologies. A total of 58,536 cluster consensus sequences were obtained, including 28,168 complete protein coding transcripts and 8,021 Long Non-coding RNAs. Significant differences were observed in the composition and content of compounds related to nutrients and taste, particularly flavonoids, during the leaf development. Our results showed a decrease in the content of most flavonoids as leaves develop. Malate and succinate accumulated with leaf development, while some sugar metabolites were decreased. Furthermore, we identified the different accumulation of amino acids and fatty acids, which are associated with taste traits. Moreover, our transcriptomic analysis provided a molecular basis for understanding the metabolic variations during leaf development. We identified 4,689 differentially expressed genes in the two developmental stages, and through a comprehensive transcriptome and metabolome analysis, we discovered the key structure genes and transcription factors involved in the pathways.

CONCLUSIONS

This study provides a high-quality reference transcriptome and reveals molecular mechanisms associated with the development of nutrients and taste components in P. juliae. These findings will enhance our understanding of the breeding and utilization of P. juliae as a vegetable.

A Full-Length Transcriptome and Analysis of the NHL-1 Gene Family in Neocaridina denticulata sinensis

Neocaridina denticulata sinensis has emerged as a promising model organism for basic studies in Decapod. However, the current transcriptome information on this species is based on next-generation sequencing technologies, which are limited by a short read length. Therefore, the present study aimed to generate a full-length transcriptome assembly of N. denticulata sinensis utilizing the PacBio Sequel Ⅱ platform. The resulting transcriptome assembly comprised 5831 transcripts with an N50 value of 3697 bp. Remarkably, 90.5% of these transcripts represented novel isoforms of known genes. The transcripts were further searched against the NR, SwissProt, KEGG, KOG, GO, NT, and Pfam databases. A total of 24.8% of the transcripts can be annotated across all seven databases. Additionally, 1236 alternative splicing events, 344 transcription factors, and 124 long non-coding RNAs (LncRNAs) were predicted. Based on the alternative splicing annotation results, a RING finger protein NHL-1 gene from N. denticulata sinensis (NdNHL-1) was identified. There are 15 transcripts in NdNHL-1. The longest transcript is 4995 bp in length and encodes a putative protein of 1665 amino acids. A phylogenetic analysis showed its close relationship with NHL-1 from other crustacean species. This report represents the full-length transcriptome of N. denticulata sinensis and will facilitate research on functional genomics and environmental adaptation in this species.

Integrative analysis of Iso-Seq and RNA-seq data reveals transcriptome complexity and differential isoform in skin tissues of different hair length Yak

BACKGROUND

The hair follicle development process is regulated by sophisticated genes and signaling networks, and the hair grows from the hair follicle. The Tianzhu white yak population exhibits differences in hair length, especially on the forehead and shoulder region. However, the genetic mechanism is still unclear. Isoform sequencing (Iso-seq) technology with advantages in long reads sequencing. Hence, we combined the Iso-seq and RNA-seq methods to investigate the transcript complexity and difference between long-haired yak (LHY) and normal-haired yak (NHY).

RESULTS

The hair length measurement result showed a significant difference between LHY and NHY on the forehead and the shoulder (P-value < 0.001). The skin samples from the forehead and the shoulder of LHY and NHY were pooled for isoform sequencing (Iso-seq). We obtained numerous long transcripts, including novel isoforms, long non-coding RNA, alternative splicing events, and alternative polyadenylation events. Combined with RNA-seq data, we performed differential isoforms (DEIs) analysis between LHY and NHY. We found that some hair follicle and skin development-related DEIs, like BMP4, KRT2, IGF2R, and COL1A2 in the forehead skin; BMP1, KRT1, FGF5, COL2A1, and IGFBP5 in the shoulder skin. Enrichment analysis revealed that DEIs in both two comparable groups significantly participated in skin and hair follicle development-related pathways, like ECM-receptor interaction, focal adhesion, and PI3K-Akt signaling pathways. The results indicated that the hair follicle development of Tianzhu white yak may influence the hair length difference. Besides, the protein-protein interaction (PPI) network of DEIs showed COL2A1 and COL3A1 exhibited a high degree of centrality, and these two genes were suggested as potential candidates for the hair length growth of Tianzhu white yak.

CONCLUSIONS

The results provided a comprehensive analysis of the transcriptome complexity and identified differential transcripts that enhance our understanding of the molecular mechanisms underlying the variation in hair length growth in Tianzhu white yak.

Giant viral signatures on the Greenland ice sheet

BACKGROUND

Dark pigmented snow and glacier ice algae on glaciers and ice sheets contribute to accelerating melt. The biological controls on these algae, particularly the role of viruses, remain poorly understood. Giant viruses, classified under the nucleocytoplasmic large DNA viruses (NCLDV) supergroup (phylum Nucleocytoviricota), are diverse and globally distributed. NCLDVs are known to infect eukaryotic cells in marine and freshwater environments, providing a biological control on the algal population in these ecosystems. However, there is very limited information on the diversity and ecosystem function of NCLDVs in terrestrial icy habitats.

RESULTS

In this study, we investigate for the first time giant viruses and their host connections on ice and snow habitats, such as cryoconite, dark ice, ice core, red and green snow, and genomic assemblies of five cultivated Chlorophyta snow algae. Giant virus marker genes were present in almost all samples; the highest abundances were recovered from red snow and the snow algae genomic assemblies, followed by green snow and dark ice. The variety of active algae and protists in these GrIS habitats containing NCLDV marker genes suggests that infection can occur on a range of eukaryotic hosts. Metagenomic data from red and green snow contained evidence of giant virus metagenome-assembled genomes from the orders Imitervirales, Asfuvirales, and Algavirales.

CONCLUSION

Our study highlights NCLDV family signatures in snow and ice samples from the Greenland ice sheet. Giant virus metagenome-assembled genomes (GVMAGs) were found in red snow samples, and related NCLDV marker genes were identified for the first time in snow algal culture genomic assemblies; implying a relationship between the NCLDVs and snow algae. Metatranscriptomic viral genes also aligned with metagenomic sequences, suggesting that NCLDVs are an active component of the microbial community and are potential "top-down" controls of the eukaryotic algal and protistan members. This study reveals the unprecedented presence of a diverse community of NCLDVs in a variety of glacial habitats dominated by algae.

Integration of hybrid and self-correction method improves the quality of long-read sequencing data

Third-generation sequencing (TGS) technologies have revolutionized genome science in the past decade. However, the long-read data produced by TGS platforms suffer from a much higher error rate than that of the previous technologies, thus complicating the downstream analysis. Several error correction tools for long-read data have been developed; these tools can be categorized into hybrid and self-correction tools. So far, these two types of tools are separately investigated, and their interplay remains understudied. Here, we integrate hybrid and self-correction methods for high-quality error correction. Our procedure leverages the inter-similarity between long-read data and high-accuracy information from short reads. We compare the performance of our method and state-of-the-art error correction tools on Escherichia coli and Arabidopsis thaliana datasets. The result shows that the integration approach outperformed the existing error correction methods and holds promise for improving the quality of downstream analyses in genomic research.

Analyses of high spatial resolution datasets identify genes associated with multi-layered secondary cell wall thickening in Pinus bungeana

BACKGROUND AND AIMS

Secondary cell wall (SCW) thickening is a major cellular developmental stage determining wood structure and properties. Although the molecular regulation of cell wall deposition during tracheary element differentiation has been well established in primary growth systems, less is known about the gene regulatory processes involved in the multi-layered SCW thickening of mature trees.

METHODS

Using third-generation [long-read single-molecule real-time (SMRT)] and second-generation [short-read sequencing by synthesis (SBS)] sequencing methods, we established a Pinus bungeana transcriptome resource with comprehensive functional and structural annotation for the first time. Using these approaches, we generated high spatial resolution datasets for the vascular cambium, xylem expansion regions, early SCW thickening, late SCW thickening and mature xylem tissues of 71-year-old Pinus bungeana trees.

KEY RESULTS

A total of 79 390 non-redundant transcripts, 31 808 long non-coding RNAs and 5147 transcription factors were annotated and quantified in different xylem tissues at all growth and differentiation stages. Furthermore, using this high spatial resolution dataset, we established a comprehensive transcriptomic profile and found that members of the NAC, WRKY, SUS, CESA and LAC gene families are major players in early SCW formation in tracheids, whereas members of the MYB and LBD transcription factor families are highly expressed during late SCW thickening.

CONCLUSIONS

Our results provide new molecular insights into the regulation of multi-layered SCW thickening in conifers. The high spatial resolution datasets provided can serve as important gene resources for improving softwoods.

Transcriptome dynamics of Gossypium purpurascens in response to abiotic stresses by Iso-seq and RNA-seq data

Gossypium purpurascens is a member of the Malvaceae family, holds immense economic significance as a fiber crop worldwide. Abiotic stresses harm cotton crops, reduce yields, and cause economic losses. Generating high-quality reference genomes and large-scale transcriptomic datasets across diverse conditions can offer valuable insights into identifying preferred agronomic traits for crop breeding. The present research used leaf tissues to conduct PacBio Iso-seq and RNA-seq analysis. We carried out an in-depth analysis of DEGs using both correlations with cluster analysis and principal component analysis. Additionally, the study also involved the identification of both lncRNAs and CDS. We have prepared RNA-seq libraries from 75 RNA samples to study the effects of drought, salinity, alkali, and saline-alkali stress, as well as control conditions. A total of 454.06 Gigabytes of transcriptome data were effectively validated through the identification of differentially expressed genes and KEGG and GO analysis. Overwhelmingly, gene expression profiles and full-length transcripts from cotton tissues will aid in understanding the genetic mechanism of abiotic stress tolerance in G. purpurascens.

Advancements in long-read genome sequencing technologies and algorithms

The recent advent of long read sequencing technologies, such as Pacific Biosciences (PacBio) and Oxford Nanopore technology (ONT), have led to substantial improvements in accuracy and computational cost in sequencing genomes. However, de novo whole-genome assembly still presents significant challenges related to the quality of the results. Pursuing de novo whole-genome assembly remains a formidable challenge, underscored by intricate considerations surrounding computational demands and result quality. As sequencing accuracy and throughput steadily advance, a continuous stream of innovative assembly tools floods the field. Navigating this dynamic landscape necessitates a reasonable choice of sequencing platform, depth, and assembly tools to orchestrate high-quality genome reconstructions. This comprehensive review delves into the intricate interplay between cutting-edge long read sequencing technologies, assembly methodologies, and the ever-evolving field of genomics. With a focus on addressing the pivotal challenges and harnessing the opportunities presented by these advancements, we provide an in-depth exploration of the crucial factors influencing the selection of optimal strategies for achieving robust and insightful genome assemblies.

Heterochronic shift in gene expression leads to ontogenetic morphological divergence between two closely related polyploid species

Heterochrony-alteration to the rate or timing of development-is an important mechanism of trait differentiation associated with speciation. Heterochrony may explain the morphological divergence between two polyploid species, June sucker (Chasmistes liorus) and Utah sucker (Catostomus ardens). The larvae of both species have terminal mouths; however, as adults, June sucker and Utah sucker develop subterminal and ventral mouths, respectively. We document a difference in the timing of shape development and a corresponding change in the timing of gene expression, suggesting the distinctive mouth morphology in June suckers may result from paedomorphosis. Specifically, adult June suckers exhibit an intermediate mouth morphology between the larval (terminal) and ancestral (ventral) states. Endemic and sympatric Chasmistes/Catostomus pairs in two other lakes also are morphologically divergent, but genetically similar. These species pairs could have resulted from the differential expression of genes and corresponding divergence in trait development. Paedomorphosis may lead to adaptive diversification in Catostomids.