A Sequel to Sanger: amplicon sequencing that scales

Host-encoded DNA methyltransferases modify the epigenome and host tropism of invading phages

Restriction modification (RM) systems are ubiquitous bacterial defense systems; however, some phages evade RM system and adapt to their bacterial hosts. In such cases, phages are thought to stochastically acquire DNA methylation from host-encoded DNA methyltransferases (MTases), facilitating host adaptation. However, no studies have directly compared the methylomes of host bacteria and their infecting phages. Here, we demonstrate the epigenetic landscape of adapted phages with diverse infection histories, focusing on the broad host-range phage KHP30T as its adapts to three Helicobacter pylori strains. Using a multistage infection system, we observed that the adapted phages displayed significantly high titers against the last infected H. pylori strain, suggesting an attendant change in host tropism. Single-molecule real-time sequencing revealed that methylated motifs were predominantly shared between the adapted phages and their most recent host. Our findings enhance our understanding of epigenetic phage-host interactions, which have significant implications for microbial ecology.

Exploratory study on source identification of saliva stain and its TsD inference based on the microbial relative and absolute abundance

In recent years, it has become a major research trend to obtain the microbial relative abundance in common body fluid stains at the crime scenes through 16S rRNA next generation sequencing to explore the effectiveness in forensic application. However, few scholars have combined the determination of tissue sources of body fluid stains with the inference of time since deposition (TsD) based on the relative and absolute abundance of microorganism in the same sample in a single study. Therefore, we preliminarily used the four abundant saliva-related bacteria to distinguish fresh saliva, saliva stains (exposure ≤60 days) from the four kinds of fresh body fluids and epidermal tissue, simultaneously assessed the temporal variation regularities in both microbial relative and absolute abundance in these saliva stains. Quantitative real-time PCR results demonstrated that fresh saliva samples and saliva stains exposed for up to 60 days still retained two or more abundant saliva-related bacteria, demonstrating sufficient discriminative power to identify saliva stain from other four kinds of body fluids and tissue. Microbial compositions and temporal analyses of 56 saliva samples revealed that many phyla and genera with abundance higher than 1% had different temporal variation regularities in relative and absolute abundance data, except for some genera such as Neisseria, etc. Beta diversity analysis indicated greater differences in absolute quantitative data among fresh saliva samples and saliva stains at different time points compared with relative quantitative data. The support vector machine (svm) model based on microbial relative or absolute abundance both have the prediction accuracy higher than 0.8 in classifying saliva stains deposited at 1 h, 1 day, and 7 to 60 days. This study combined the tissue origin identification and TsD inference of saliva stains, and the absolute quantitative technology was applied for the first time to the TsD inference of saliva stains. And the results indicated that using the absolute quantitative technology might be more suitable for early TsD inference (within 14 days) of saliva stains in this study, which helped to accurately infer the TsD of saliva stains, providing an important clue for forensic investigation.

Comparison of HIV-1 RNA and HIV-1 DNA Genotypic Drug Resistance Testing in Women of Childbearing Age Infected with HIV-1 in Liangshan Prefecture

This study focuses on women of childbearing age infected with HIV-1 in Liangshan Prefecture and analyses their HIV-1 RNA and HIV-1 DNA genotypic drug resistance to provide a theoretical basis and technical support for monitoring the spread of resistant strains and formulating and optimizing antiretroviral therapy regimens. The study subjects were women of childbearing age infected with HIV-1 who were followed up in the county of Liangshan Prefecture from January to September 2023. Peripheral venous blood samples were collected from each subject. The samples were centrifuged to separate the plasma and blood cells for HIV-1 RNA quantitative testing and HIV-1 genotypic drug resistance testing. A total of 47 participants were included in this study. When HIV-1 RNA were <50 copies/mL and between 50 and 1,000 copies/mL, the success rate of HIV-1 DNA pol gene amplification was significantly higher than that of HIV-1 RNA pol gene amplification. Among the 47 subjects, 17 (17/47, 36.17%) indicated successfully amplified HIV-1 RNA and HIV-1 DNA genotypic drug resistance in each region simultaneously, and 9 (9/17, 52.94%) developed any degree of resistance. Among these nine cases, five had consistent resistance, while four indicated inconsistent resistance. Among the five cases with identical drug resistance, there were three cases with inconsistent drug resistance mutations (DRMs). Among the four cases with inconsistent drug resistance results, one had DRMs at the HIV-1 DNA level but no DRMs at the HIV-1 RNA level, while the other three had more DRMs at the HIV-1 RNA level than at the HIV-1 DNA level. The combination of HIV-1 RNA and HIV-1 DNA genotypic drug resistance testing can improve the drawbacks of current single HIV-1 RNA genotypic drug resistance testing, especially when HIV-1 RNA is ≤1,000 copies/mL, and significantly improve the efficiency of HIV-1 genotypic drug resistance testing.

Chromosome-scale genomes of ecologically and economically important rabbitfish Siganus guttatus and Siganus oramin

Siganus guttatus and Siganus oramin are two major species that are naturally distributed along the Eastern Pacific coast and possess considerable ecological and economic value. Here, we present the construction and comparative analysis of the chromosome-level genomes of these two Siganus species. Employing a hybrid assembly strategy, we partitioned and independently assembled the PacBio, Illumina and Hi-C reads of S. guttatus and S. oramin, resulting in chromosome-level genomes. The assembly sizes (N50 size, BUSCO completeness) of the two genomes were 642.4 M (25.76 M, 98.26 %) and 502.8 M (16.98 M, 98.8 %) for S. guttatus and S. oramin, respectively, exhibiting high contiguity and integrity. This study marks the first successful assembly of chromosome-level genomes in Siganus species, along with an initial exploration of their dietary habits and habitats through comparative genomics analysis. These findings offer essential resources for comparative genomics and molecular evolution research.

Network Assemblages of Elevational Niche-Associated Diversity in Fijian Native Bees

Species assemblages constrained by ecological and evolutionary processes (and the interactions between them) are vulnerable to changes in their environment. Network analyses do not explicitly build in phylogenetic histories when exploring how they are assembled, yet they can be a critical source of information for understanding how and when species may be incorporated into ecological webs. Recent studies have revealed unexpected species diversity in a monophyletic clade of native Fijian bees in the subgenus Lasioglossum (Homalictus). These bees have undergone a remarkable and recent radiation with evidence for phylogenetic conservatism in elevational niches and physiological traits. Here we use bipartite network analyses, as an adjunct to phylogenetic analyses, to further inform likely ancestral elevations for these bees and to explore patterns in how they have occupied other elevational niches. Our approach is novel in that we categorize elevation into bands that are then treated as the lower hierarchical level onto which we map individual bee species. These analyses support earlier inferences that highland elevations (or the climates that correspond to them) are ancestral niches and that barriers to occupation of lower elevations are significant. In addition, we provide important insights into co-occupancy of elevational niches and whether competition occurs for these niches. Our results suggest convergences in niche expansion and a lack of competitive exclusion for those specific niches, but a strong extinction risk for loss of current elevation-related niches.

Comparative analysis of the human microbiome from four different regions of China and machine learning-based geographical inference

The human microbiome, the community of microorganisms that reside on and inside the human body, is critically important for health and disease. However, it is influenced by various factors and may vary among individuals residing in distinct geographic regions. In this study, 220 samples, consisting of sterile swabs from palmar skin and oral and nasal cavities were collected from Chinese Han individuals living in Shanghai, Chifeng, Kunming, and Urumqi, representing the geographic regions of east, northeast, southwest, and northwest China. The full-length 16S rRNA gene of the microbiota in each sample was sequenced using the PacBio single-molecule real-time sequencing platform, followed by clustering the sequences into operational taxonomic units (OTUs). The analysis revealed significant differences in microbial communities among the four regions. Cutibacterium was the most abundant bacterium in palmar samples from Shanghai and Kunming, Psychrobacter in Chifeng samples, and Psychrobacillus in Urumqi samples. Additionally, Streptococcus and Staphylococcus were the dominant bacteria in the oral and nasal cavities. Individuals from the four regions could be distinguished and predicted based on a model constructed using the random forest algorithm, with the predictive effect of palmar microbiota being better than that of oral and nasal cavities. The prediction accuracy using hypervariable regions (V3-V4 and V4-V5) was comparable with that of using the entire 16S rRNA. Overall, our study highlights the distinctiveness of the human microbiome in individuals living in these four regions. Furthermore, the microbiome can serve as a biomarker for geographic origin inference, which has immense application value in forensic science.IMPORTANCEMicrobial communities in human hosts play a significant role in health and disease, varying in species, quantity, and composition due to factors such as gender, ethnicity, health status, lifestyle, and living environment. The characteristics of microbial composition at various body sites of individuals from different regions remain largely unexplored. This study utilized single-molecule real-time sequencing technology to detect the entire 16S rRNA gene of bacteria residing in the palmar skin, oral, and nasal cavities of Han individuals from four regions in China. The composition and structure of the bacteria at these three body sites were well characterized and found to differ regionally. The results elucidate the differences in bacterial communities colonizing these body sites across different regions and reveal the influence of geographical factors on human bacteria. These findings not only contribute to a deeper understanding of the diversity and geographical distribution of human bacteria but also enrich the microbiome data of the Asian population for further studies.

Illuminating Entomological Dark Matter with DNA Barcodes in an Era of Insect Decline, Deep Learning, and Genomics

Most insects encountered in the field are initially entomological dark matter in that they cannot be identified to species while alive. This explains the enduring quest for efficient ways to identify collected specimens. Morphological tools came first but are now routinely replaced or complemented with DNA barcodes. Initially too expensive for widespread use, these barcodes have since evolved into powerful tools for specimen identification and sorting, given that the evolution of sequencing approaches has dramatically reduced the cost of barcodes, thus enabling decentralized deployment across the planet. In this article, we review how DNA barcodes have become a key tool for accelerating biodiversity discovery and analyzing insect communities through both megabarcoding and metabarcoding in an era of insect decline. We predict that DNA barcodes will be particularly important for assembling image training sets for deep learning algorithms, global biodiversity genomics, and functional analysis of insect communities.

Looking Into the Abyss-How Many Species of Biting Midges (Diptera: Ceratopogonidae) Are There? Their Remarkable Diversity in Costa Rica and Elsewhere

The biting midges (Ceratopogonidae) are one of the most species-rich families of insects on the planet with over 6,200 named species. However, their true diversity is unknown and this paper is the first to address the question. Our systematic study of the family in Costa Rica indicates that 192 species were present in a four hectare area of cloudforest at Zurquí de Moravia, at 1,600 m after a year of intensive sampling. Combined with a collection from a single Malaise trap at Tapantí for one year, about 40 kms away and also at 1,600 m, the total was 245 species with significant differences between the two areas and with the strong majority unnamed. This compares to 430 named species for all of Costa Rica and 1,314 for the entire Neotropical Region. Barcoding of 221,407 specimens from Costa Rica similarly indicates large numbers of unnamed species with 4,023 BINs present. On this basis, we project at least 5,000 species in Costa Rica and using ratios of named species here and elsewhere, we suggest that nearly 73,000 are present worldwide. Details from Malaise traps in the Área de Conservación Guanacaste also indicate various levels of endemism. Samples from Bolivia support an interpretation of high diversity. The diversification of the family was examined by comparing phyletic lineages, rather than merely comparing numbers of species in various genera, providing insight as to why some lineages are more diverse than others. Zoogeographic patterns of named species suggest stronger southern connections for Costa Rican Ceratopogonidae in both cloudforest habitats as well as the country as a whole, although many are also more broadly distributed north and south of the country. Comparisons between various collecting methods at Zurquí de Moravia indicate the efficacy of Malaise traps but also the importance of light traps and other methods in sampling adults of Ceratopogonidae. Phenological data from the Malaise traps in the Área de Conservación Guanacaste suggest some patterns of emergence of adults in Costa Rica, the first for any tropical country anywhere.

Comparing Gold-Standard Sanger Sequencing with Two Next-Generation Sequencing Platforms of HIV-1 gp160 Single Genome Amplicons

Our goal was to assess the accuracy of next generation sequencing (NGS) compared with Sanger. We performed single genome amplification (SGA) of HIV-1 gp160 on extracted tissue DNA from two HIV+ individuals. Amplicons (n = 30) were sequenced with Sanger or reamplified with barcoded primers and pooled before sequencing using Oxford Nanopore Technologies (ONT) and Pacific Biosciences (PB). For each amplicon, a consensus sequence for NGS reads was obtained by (1) mapping reads to the Sanger sequence when available ("reference-based") or (2) mapping reads to a "pseudo-reference" sequence, i.e., a consensus sequence of a subset of NGS reads ("reference-free"). PB reads were clustered based on genetic similarity. A Sanger consensus sequence was obtained for 23/30 amplicons, for which all NGS consensus sequences were identical (n = 9) or nearly identical (n = 14) compared with Sanger. For the nine mismatches between Sanger/NGS, the nucleotide in the NGS sequence matched all other sequences from that patient. Of the 7/30 amplicons without a Sanger sequence, NGS sequences had ≥35 ambiguous calls in five amplicons and 0 ambiguities in two amplicons. Analysis of the electropherograms showed failure of a single sequencing primer for the latter two amplicons (consistent with a single template) and overlapping peaks for the other five (consistent with multiple templates). Clustering results closely followed the Sanger/NGS consensus results, where amplicons derived from a single template also had a single cluster and vice versa (with one exception, which could be the result of barcode misidentification). Representative sequences from the clusters contained 2-13 differences compared with Sanger/NGS. In summary, we show that both ONT and PB can produce amplicon consensus sequences with similar or higher accuracy compared with Sanger and, importantly, without the need for a known reference sequence. Clustering could be useful in some circumstances to predict or confirm the presence of multiple starting templates.

Exploring the diversity of Gracillariidae (Lepidoptera) in South Africa: host plants, distribution, and DNA barcoding analysis, with the description of nine new species

Despite relatively extensive historical exploration being carried out on Lepidopteran fauna of South Africa, leaf-mining micromoths of the family Gracillariidae remain a source of discovery, with many new species awaiting description. In the present work, 32 gracillariid species from South Africa are treated. For each species, hostplant and distribution information is provided, supplemented by taxonomic and molecular analysis where necessary. Nine species are described here as new to science: Ectropina spirostachydis sp. nov., Leucocercops curatellifoliae sp. nov., Phodoryctis tephrosiella sp. nov., Telamoptilia cordati sp. nov., Phyllonorycter pseudogrewiella sp. nov., Cameraria melhaniella sp. nov., Phyllocnistis magalismontani sp. nov., P. allisonae sp. nov. and P. faureae sp. nov. Sixteen host plant species are reported for the first time for the family Gracillariidae: Searsia pyroides (Anacardiaceae), Parinari curatellifolia (Chrysobalanaceae), Combretum zeyheri, Terminalia sericea (Combretaceae), Euclea divinorum (Ebenaceae), Spirostachys africana (Euphorbiaceae), Peltophorum africanum, Tephrosia rhodesica, Schotia brachypetala (Fabaceae), Cryptocarya transvaalensis (Lauraceae), Melhania acuminata (Malvaceae), Syzygium guineense (Myrtaceae), Ochna pretoriensis (Ochnaceae), Protea rubropilosa, Faurea saligna (Proteaceae), Englerophytum magalismontanum (Sapotaceae). Caloptilia mwamba De Prins, 2015 is recorded for the first time in South Africa.

Beyond simple tails: poly(A) tail-mediated RNA epigenetic regulation

The poly(A) tail is an essential structural component of mRNA required for the latter's stability and translation. Recent technologies have enabled transcriptome-wide profiling of the length and composition of poly(A) tails, shedding light on their overlooked regulatory capacities. Notably, poly(A) tails contain not only adenine but also uracil, cytosine, and guanine residues. These findings strongly suggest that poly(A) tails could encode a wealth of regulatory information, similar to known reversible RNA chemical modifications. This review aims to succinctly summarize our current knowledge on the composition, dynamics, and regulatory functions of RNA poly(A) tails. Given their capacity to carry rich regulatory information beyond the genetic code, we propose the concept of 'poly(A) tail epigenetic information' as a new layer of RNA epigenetic regulation.

Solving the twin paradox-forensic strategies to identify the identical twins

Identical twins are also called monozygotic twins which originate from the same zygote that possesses the same genetic make-up. To discriminate between identical monozygotic twins, short tandem repeats has not been found effective, therefore, various techniques, including next-generation sequencing (NGS), are applied. Monozygotic twins can be identified through germ line genomes, through speech using deep learning networks, and through epigenetic analysis. Fingerprint analysis has also been used to distinguish between identical twins, as human beings have unique fingerprints. Two distinct levels of fingerprint are used to distinguish between monozygotic twins based upon the differences in the minutiae points. Examination of the methylation pattern of the genome has an enormous potential to differentiate between identical twins, as the methylation of DNA occurs uniquely to each individual. This article offers an insight into the latest methods and techniques used for the differentiation between the identical twins.

Descriptions of three new species of Lycaenidae (Lepidoptera: Papilionoidea) from Parc National de Nouabalé-Ndoki, Republic of Congo with additional notes on little-known species

Three new species of Lycaenidae, Falcuna nouabaleensis sp. nov., Anthene sangha sp. nov. and Neurellipes smithi sp. nov. are described from material collected during recent African Natural History Research Trust expeditions to Parc National de Nouabalé-Ndoki in northern Republic of Congo. Several other interesting taxa were also sampled including the unknown male of Ornipholidotos ghesquierei Libert, 2005 and a short series of unidentified female Pilodeudorix Druce, 1891 specimens near P. catori (Bethune-Baker, 1903) which are all illustrated. The distribution of species in this area of Central Africa is discussed in relation to the biogeography of the interfluvial region between the Sangha and Congo Rivers.

Morphology and DNA barcodes of four species of Bradysia hilaris group from China (Diptera, Sciaridae)

Four morphologically allied species of the Bradysia hilaris group were studied from China. In a DNA metabarcoding based dipteran diversity study in Zhejiang, eastern China, a hyper-abundant sciarid species was discovered. It was further recognized in this study to be new to science, Bradysia tianmuensis Du & Huang sp. nov., as well as a morphologically similar species, Bradysia curvula Du & Huang sp. nov. Both new species were found to be fairly similar morphologically to the holotype of Bradysia noduspina Yang, Zhang & Yang, 1993 from Guizhou in western China. However, the paratype of B. noduspina appeared to be different from the holotype and determined to be new to science, Bradysia chikunae Du & Huang sp. nov. A phylogenetic tree of all the available 31 COI sequences of the Bradysia hilaris group was provided. Molecular work conducted in the current study also supports Bradysia tianmuensis Du & Huang sp. nov. and Bradysia curvula Du & Huang sp. nov. as new to science thus the four species were described or redescribed accompanied by detailed imagery of habitus and other characters useful for determination.

The Lasiocampidae (Lepidoptera: Lasiocampoidea) of Maputo Special Reserve, Mozambique: a provisional checklist with descriptions of three new species and taxonomic notes

A preliminary checklist of 39 species of lappet moths (Lasiocampidae) is provided for Maputo Special Reserve in southern Mozambique of which three are new to science, Diapalpus smithi sp. n., Eutricha giustii sp. n. and Rhinobombyx maputoensis sp. n., and a further ten are new country records. Several taxonomic changes are implemented in this paper: the synonymy of Sena prompta plusioides (Walker, 1862) syn. rev. with Sena prompta (Walker, 1855) is revived, Bombycopsis (Bufoidia) pallida Joannou & Krüger, 2009 syn. n. is synonymised with B. (B.) nigrovittata Aurivillius, 1927, and Lebeda mustelina Distant, 1899 is transferred to Leipoxais Holland, 1893 comb. n. Additionally, it is shown that the neotype designation by Zolotuhin & Gurkovich (2009) for Lebeda morosa Walker, 1865 is invalid although a new neotype is not selected as the original type may still be extant. All species, forms and both sexes where present are figured, as are the genitalia in the case of the new species and the comparative material examined.

A new species of Ducetia (Tettigoniidae, Phaneropterinae) from Mindanao, Philippines based on bioacoustics, stridulatory file morphology and genetic data

The Ducetia japonica species group consists of 11 species widely distributed in Asia and Australia. It includes a single species from the Philippines: Ducetia adspersa Brunner von Wattenwyl, 1878. Previously synonymized under Ducetia japonica (Thunberg, 1815), this species was resurrected for its unique stridulatory file. Based on its distinct stridulatory file morphology, male calling song and cytochrome c oxidase subunit I signature, we discovered and describe here a new species from Mindanao in the south of the Philippines: Ducetia laniae sp. nov. We also describe the calling song of this new species. This discovery underscores the rich biodiversity of the region and highlights the necessity for continued exploration and study to unravel the complexities within this genus.

Assessing arthropod biodiversity with DNA barcoding in Jinnah Garden, Lahore, Pakistan

Previous difficulties in arthropod taxonomy (such as limitations in conventional morphological approaches, the possibility of cryptic species and a shortage of knowledgeable taxonomists) has been overcome by the powerful tool of DNA barcoding. This study presents a thorough analysis of DNA barcoding in regards to Pakistani arthropods, which were collected from Lahore's Jinnah Garden. The 88 % (9,451) of the 10,792 specimens that were examined were able to generate DNA barcodes and 83% (8,974) of specimens were assigned 1,361 barcode index numbers (BINs). However, the success rate differed significantly between the orders of arthropods, from 77% for Thysanoptera to an astounding 93% for Diptera. Through morphological exams, DNA barcoding, and cross-referencing with the Barcode of Life Data system (BOLD), the Barcode Index Numbers (BINs) were assigned with a high degree of accuracy, both at the order (100%) and family (98%) levels. Though, identifications at the genus (37%) and species (15%) levels showed room for improvement. This underscores the ongoing need for enhancing and expanding the DNA barcode reference library. This study identified 324 genera and 191 species, underscoring the advantages of DNA barcoding over traditional morphological identification methods. Among the 17 arthropod orders identified, Coleoptera, Diptera, Hemiptera, Hymenoptera, and Lepidoptera from the class Insecta dominated, collectively constituting 94% of BINs. Expected malaise trap Arthropod fauna in Jinnah Garden could contain approximately 2,785 BINs according to Preston log-normal species distribution, yet the Chao-1 Index predicts 2,389.74 BINs. The Simpson Index of Diversity (1-D) is 0.989, signaling high species diversity, while the Shannon Index is 5.77, indicating significant species richness and evenness. These results demonstrated that in Pakistani arthropods, DNA barcoding and BOLD are an invaluable tool for improving taxonomic understanding and biodiversity assessment, opening the door for further eDNA and metabarcoding research.

A new species and a new record of Urytalpa Edwards, 1929 (Diptera: Keroplatidae) from China

One new species and a new record of Urytalpa (Diptera: Keroplatidae: Keroplatinae), U. leigongshana sp. n. and U. yoshidai Uesugi, are described in this paper, which were collected from Guizhou and Sichuan, China. The molecular identification and morphological description of U. leigongshana are provided, together with the adult images of these two species. Furthermore, this paper also offers a worldwide distribution map and a checklist of this genus.

Evolutionary insights from profiling LINE-1 activity at allelic resolution in a single human genome

Transposable elements have created the majority of the sequence in many genomes. In mammals, LINE-1 retrotransposons have been expanding for more than 100 million years as distinct, consecutive lineages; however, the drivers of this recurrent lineage emergence and disappearance are unknown. Most human genome assemblies provide a record of this ancient evolution, but fail to resolve ongoing LINE-1 retrotranspositions. Utilizing the human CHM1 long-read-based haploid assembly, we identified and cloned all full-length, intact LINE-1s, and found 29 LINE-1s with measurable in vitro retrotransposition activity. Among individuals, these LINE-1s varied in their presence, their allelic sequences, and their activity. We found that recently retrotransposed LINE-1s tend to be active in vitro and polymorphic in the population relative to more ancient LINE-1s. However, some rare allelic forms of old LINE-1s retain activity, suggesting older lineages can persist longer than expected. Finally, in LINE-1s with in vitro activity and in vivo fitness, we identified mutations that may have increased replication in ancient genomes and may prove promising candidates for mechanistic investigations of the drivers of LINE-1 evolution and which LINE-1 sequences contribute to human disease.

A new species of Karschiola Gaede from Mozambique and Zimbabwe (Lepidoptera: Erebidae: Arctiinae) with updated information on the distribution of the genus

The present paper provides the description of a new species of the genus Karschiola Gaede, 1926 from central Mozambique and Zimbabwe: K. ndzou sp. n. The pairwise genetic distance between the two Karschiola species is calculated and a neighbour-joining tree based on DNA barcodes of two K. holoclera and five K. ndzou sp. n. specimens is provided. The paper is illustrated with eight colour photos of adults and 18 genitalia images, a distribution map and two habitat photos.

Genomics in the long-read sequencing era

Long-read sequencing (LRS) technologies have provided extremely powerful tools to explore genomes. While in the early years these methods suffered technical limitations, they have recently made significant progress in terms of read length, throughput, and accuracy and bioinformatics tools have strongly improved. Here, we aim to review the current status of LRS technologies, the development of novel methods, and the impact on genomics research. We will explore the most impactful recent findings made possible by these technologies focusing on high-resolution sequencing of genomes and transcriptomes and the direct detection of DNA and RNA modifications. We will also discuss how LRS methods promise a more comprehensive understanding of human genetic variation, transcriptomics, and epigenetics for the coming years.

Trait-mediated responses of caterpillar communities to spongy moth outbreaks and subsequent tebufenozide treatments

Outbreaks of the spongy moth Lymantria dispar can have devastating impacts on forest resources and ecosystems. Lepidoptera-specific insecticides, such as Bacillus thuringiensis var. kurstaki (BTK) and tebufenozide, are often deployed to prevent heavy defoliation of the forest canopy. While it has been suggested that using BTK poses less risk to non-target Lepidoptera than leaving an outbreak untreated, in situ testing of this assumption has been impeded by methodological challenges. The trade-offs between insecticide use and outbreaks have yet to be addressed for tebufenozide, which is believed to have stronger side effects than BTK. We investigated the short-term trade-offs between tebufenozide treatments and no-action strategies for the non-target herbivore community in forest canopies. Over 3 years, Lepidoptera and Symphyta larvae were sampled by canopy fogging in 48 oak stands in southeast Germany during and after a spongy moth outbreak. Half of the sites were treated with tebufenozide and changes in canopy cover were monitored. We contrasted the impacts of tebufenozide and defoliator outbreaks on the abundance, diversity, and functional structure of chewing herbivore communities. Tebufenozide treatments strongly reduced Lepidoptera up to 6 weeks after spraying. Populations gradually converged back to control levels after 2 years. Shelter-building species dominated caterpillar assemblages in treated plots in the post-spray weeks, while flight-dimorphic species were slow to recover and remained underrepresented in treated stands 2 years post-treatment. Spongy moth outbreaks had minor effects on leaf chewer communities. Summer Lepidoptera decreased only when severe defoliation occurred, whereas Symphyta declined 1 year after defoliation. Polyphagous species with only partial host plant overlap with the spongy moth were absent from heavily defoliated sites, suggesting greater sensitivity of generalists to defoliation-induced plant responses. These results demonstrate that both tebufenozide treatments and spongy moth outbreaks alter canopy herbivore communities. Tebufenozide had a stronger and longer lasting impact, but it was restricted to Lepidoptera, whereas the outbreak affected both Lepidoptera and Symphyta. These results are tied to the fact that only half of the outbreak sites experienced severe defoliation. This highlights the limited accuracy of current defoliation forecast methods, which are used as the basis for the decision to spray insecticides.

Beyond assembly: the increasing flexibility of single-molecule sequencing technology

The maturation of high-throughput short-read sequencing technology over the past two decades has shaped the way genomes are studied. Recently, single-molecule, long-read sequencing has emerged as an essential tool in deciphering genome structure and function, including filling gaps in the human reference genome, measuring the epigenome and characterizing splicing variants in the transcriptome. With recent technological developments, these single-molecule technologies have moved beyond genome assembly and are being used in a variety of ways, including to selectively sequence specific loci with long reads, measure chromatin state and protein-DNA binding in order to investigate the dynamics of gene regulation, and rapidly determine copy number variation. These increasingly flexible uses of single-molecule technologies highlight a young and fast-moving part of the field that is leading to a more accessible era of nucleic acid sequencing.

Integrative taxonomic revision of the Metarctia Walker, 1855 subgenus HebenaWalker, 1856, with descriptions of six new species and one new subspecies(Lepidoptera: Erebidae: Arctiinae: Syntomini)

A revision of the subgenus Hebena Walker, 1856 of the syntomine genus Metarctia Walker, 1855 is given based on integrative taxonomic analyses. Six new species (Metarctia (Hebena) manfredi sp. n., M. (H.) elleni sp. n., M. (H.) brigitta sp. n., M. (H). lukaszi sp. n., M. (H.) smithi sp. n., and M. (H.) haraldsulaki sp.n.) and one new subspecies (M. (H.) smithi transvallesiana ssp. n.) are described. Metarctia (H.) kelleni (Snellen, 1886) stat. rev. is reinstated from synonymy with M. (H.) rubra (Walker, 1856) and Metarctia (H.) subincarnata Kiriakoff, 1954 syn. n. is synonymised with M. (H.) henrardi Kiriakoff, 1953 and Metarctia cinnamomea (Wallengren, 1860) syn. n. with M. (H.) rubra (Walker, 1856). DNA barcodes were obtained for 116 specimens representing 7 taxa, and genetic analyses were performed using Maximum Likelihood and Bayesian Inference approaches; a DNA barcode tree resulting from the latter is illustrated. Pairwise distances of barcodes between taxa are provided where available. The adults and genitalia of all taxa, their habitats and distribution are illustrated in 19 colour plates and 5 distribution maps.

Palaearctic willow-catkin sawflies: a revision of the amentorum species group of Euura (Hymenoptera, Tenthredinidae)

The Euura amentorum species group is Holarctic, and in Europe it is most species-rich in the North. Their larvae develop entirely within the female catkins of Salix species: some species bore in the central stalk, whereas others live outside this and feed mainly on the developing seeds. Eight Palaearctic species are treated here as valid, and a key to these is provided. Males of five species are known. Two new species are described from northern Europe: Euura pohjola sp. n. and E. ursaminor sp. n. First records of E. itelmena (Malaise, 1931) from the West Palaearctic are presented. We propose seven new synonymies: Pontopristia montana Lindqvist, 1961 (junior secondary homonym in Euura) with Euura freyja (Liston, Taeger & Blank, 2009); Pontopristia brevilabris Malaise, 1921, Amauronematus fennicus Lindqvist, 1944, Pontopristia boreoalpina Lindqvist, 1961, Pontopristia punctulata Lindqvist, 1961, and Amauronematus pyrenaeus Lacourt, 1995 with Euura microphyes (Frster, 1854); and Pteronidea holmgreni Lindqvist, 1968 with Nematus umbratus Thomson, 1871. Lectotypes are designated for: Amauronematus fennicus Lindqvist, 1944, Nematus amentorum Frster, 1854, Nematus suavis Ruthe, 1859, Pontopristia brevilabris Malaise, 1921, Pontopristia itelmena Malaise, 1931, Pontopristia kamtchatica Malaise, 1931, Pontopristia lapponica Malaise, 1921, Pontopristia latiserra Malaise, 1921, Pontopristia romani Malaise, 1921, and Pristiphora amentorum var. nigripleuris Enslin, 1916. Many new host plant associations are recorded.

A new species of Neurothaumasia Le Marchand (Lepidoptera, Tineidae) from Crete, Greece

A new species of fungus moths (Tineidae), Neurothaumasia cretica sp. nov., is described from specimens collected on Crete isl. (Greece). It differs from congeneric taxa by the characteristic black and white forewing pattern which is only shared with N. fasciata Petersen, 1959 from the Middle East, and the widespread western Palaearctic N. ankerella (Mann, 1867). However, the new species differs strongly from the former by several characters of male and female genitalia, and from the latter species particularly from external appearance and by the highly divergent DNA barcode (cytochrome c-oxidase subunit 1) (unknown for N. fasciata). Adult and genitalia of N. cretica sp. nov. and the only similar European species N. ankerella are shown for comparison. Finally, a complete checklist of the genus is added.

Integrative taxonomic revision of the African taxa of the Racotis Moore, 1887 generic complex (Lepidoptera, Geometridae, Ennominae, Boarmiini)

The Afrotropical taxa of the Racotis s.l. generic complex are revised utilising integrative taxonomical methods. Based on the evaluation of genital morphology and analyses of DNA barcodes, a new genus, Afroracotis gen. n. is established to include the Afrotropical "Racotis" species. The new genus is subdivided into 5 subgenera: Afroracotis subgen. n., Herbuloracotis subgen. n., Rwandaracotis subgen. n., Zebracotis subgen. n. and Sokokeracotis subgen. n.. A new monotypic genus is described to include Boarmia ugandaria Swinhoe, 1904 which was combined earlier with the genus Chorodna and recently with Racotis: Chorocotis gen. n.. Two species formerly assigned to Cleora are moved to Afroracotis: A. albitrigonis (Prout, 1927) comb. n., A. atriclava (Prout, 1926) comb. n.. Two species are transferred from Racotis to Colocleora: C. breijeri (Prout, 1922) comb. n., C. incauta (Prout, 1916) comb. n.. Seventeen new Afroracotis species (A. aliena, A. stadiei, A. violetteae, A. fiebigi, A. turlini, A. dargei, A. longicornuta, A. aristophanousi, A. muscivirens, A. chaineyi, A. lydiae, A. smithi, A. ochsei, A. milesi, A. helicalis, A. takanoi and A. staudei spp. n.) and 5 new subspecies (A. squalida thomensis, A. argillacea morettoi, A. longicornuta congolana, A. longicornuta ugandana and A. lydiae orientalis sspp. n.) are described, totalling 27 species and 8 subspecies contained in the genus Afroracotis. Adults and genitalia of all taxa are illustrated in 210 colour and 129 black and white figures demonstrating the intraspecific variability. The distribution of all taxa is illustrated in 6 dot maps. The results of the genetic analyses are figured in four phylograms.

Interrogating 1000 insect genomes for NUMTs: A risk assessment for estimates of species richness

The nuclear genomes of most animal species include NUMTs, segments of the mitogenome incorporated into their chromosomes. Although NUMT counts are known to vary greatly among species, there has been no comprehensive study of their frequency/attributes in the most diverse group of terrestrial organisms, insects. This study examines NUMTs derived from a 658 bp 5' segment of the cytochrome c oxidase I (COI) gene, the barcode region for the animal kingdom. This assessment is important because unrecognized NUMTs can elevate estimates of species richness obtained through DNA barcoding and derived approaches (eDNA, metabarcoding). This investigation detected nearly 10,000 COI NUMTs ≥ 100 bp in the genomes of 1,002 insect species (range = 0-443). Variation in nuclear genome size explained 56% of the mitogenome-wide variation in NUMT counts. Although insect orders with the largest genome sizes possessed the highest NUMT counts, there was considerable variation among their component lineages. Two thirds of COI NUMTs possessed an IPSC (indel and/or premature stop codon) allowing their recognition and exclusion from downstream analyses. The remainder can elevate species richness as they showed 10.1% mean divergence from their mitochondrial homologue. The extent of exposure to "ghost species" is strongly impacted by the target amplicon's length. NUMTs can raise apparent species richness by up to 22% when a 658 bp COI amplicon is examined versus a doubling of apparent richness when 150 bp amplicons are targeted. Given these impacts, metabarcoding and eDNA studies should target the longest possible amplicons while also avoiding use of 12S/16S rDNA as they triple NUMT exposure because IPSC screens cannot be employed.

A workflow for expanding DNA barcode reference libraries through 'museum harvesting' of natural history collections

Natural history collections are the physical repositories of our knowledge on species, the entities of biodiversity. Making this knowledge accessible to society - through, for example, digitisation or the construction of a validated, global DNA barcode library - is of crucial importance. To this end, we developed and streamlined a workflow for 'museum harvesting' of authoritatively identified Diptera specimens from the Smithsonian Institution's National Museum of Natural History. Our detailed workflow includes both on-site and off-site processing through specimen selection, labelling, imaging, tissue sampling, databasing and DNA barcoding. This approach was tested by harvesting and DNA barcoding 941 voucher specimens, representing 32 families, 819 genera and 695 identified species collected from 100 countries. We recovered 867 sequences (> 0 base pairs) with a sequencing success of 88.8% (727 of 819 sequenced genera gained a barcode > 300 base pairs). While Sanger-based methods were more effective for recently-collected specimens, the methods employing next-generation sequencing recovered barcodes for specimens over a century old. The utility of the newly-generated reference barcodes is demonstrated by the subsequent taxonomic assignment of nearly 5000 specimen records in the Barcode of Life Data Systems.

Highly-multiplexed and efficient long-amplicon PacBio and Nanopore sequencing of hundreds of full mitochondrial genomes

BACKGROUND

Mitochondrial genome sequences have become critical to the study of biodiversity. Genome skimming and other short-read based methods are the most common approaches, but they are not well-suited to scale up to multiplexing hundreds of samples. Here, we report on a new approach to sequence hundreds to thousands of complete mitochondrial genomes in parallel using long-amplicon sequencing. We amplified the mitochondrial genome of 677 specimens in two partially overlapping amplicons and implemented an asymmetric PCR-based indexing approach to multiplex 1,159 long amplicons together on a single PacBio SMRT Sequel II cell. We also tested this method on Oxford Nanopore Technologies (ONT) MinION R9.4 to assess if this method could be applied to other long-read technologies. We implemented several optimizations that make this method significantly more efficient than alternative mitochondrial genome sequencing methods.

RESULTS

With the PacBio sequencing data we recovered at least one of the two fragments for 96% of samples (~ 80-90%) with mean coverage ~ 1,500x. The ONT data recovered less than 50% of input fragments likely due to low throughput and the design of the Barcoded Universal Primers which were optimized for PacBio sequencing. We compared a single mitochondrial gene alignment to half and full mitochondrial genomes and found, as expected, increased tree support with longer alignments, though whole mitochondrial genomes were not significantly better than half mitochondrial genomes.

CONCLUSIONS

This method can effectively capture thousands of long amplicons in a single run and be used to build more robust phylogenies quickly and effectively. We provide several recommendations for future users depending on the evolutionary scale of their system. A natural extension of this method is to collect multi-locus datasets consisting of mitochondrial genomes and several long nuclear loci at once.

A practical comparison of the next-generation sequencing platform and assemblers using yeast genome

Assembling fragmented whole-genomic information from the sequencing data is an inevitable process for further genome-wide research. However, it is intricate to select the appropriate assembly pipeline for unknown species because of the species-specific genomic properties. Therefore, our study focused on relatively more static proclivities of sequencing platforms and assembly algorithms than the fickle genome sequences. A total of 212 draft and polished de novo assemblies were constructed under the different sequencing platforms and assembly algorithms with the repetitive yeast genome. Our comprehensive data indicated that sequencing reads from Oxford Nanopore with R7.3 flow cells generated more continuous assemblies than those derived from the PacBio Sequel, although the homopolymer-based assembly errors and chimeric contigs exist. In addition, the comparison between two second-generation sequencing platforms showed that Illumina NovaSeq 6000 provides more accurate and continuous assembly in the second-generation-sequencing-first pipeline, but MGI DNBSEQ-T7 provides a cheap and accurate read in the polishing process. Furthermore, our insight into the relationship among the computational time, read length, and coverage depth provided clues to the optimal pipelines of yeast assembly.

Future of DNA-based insect monitoring

Insects are crucial for ecosystem health but climate change and pesticide use are driving massive insect decline. To mitigate this loss, we need new and effective monitoring techniques. Over the past decade there has been a shift to DNA-based techniques. We describe key emerging techniques for sample collection. We suggest that the selection of tools should be broadened, and that DNA-based insect monitoring data need to be integrated more rapidly into policymaking. We argue that there are four key areas for advancement, including the generation of more complete DNA barcode databases to interpret molecular data, standardisation of molecular methods, scaling up of monitoring efforts, and integrating molecular tools with other technologies that allow continuous, passive monitoring based on images and/or laser imaging, detection, and ranging (LIDAR).

VLF: An R package for the analysis of very low frequency variants in DNA sequences

Here, we introduce VLF, an R package to determine the distribution of very low frequency variants (VLFs) in nucleotide and amino acid sequences for the analysis of errors in DNA sequence records. The package allows users to assess VLFs in aligned and trimmed protein-coding sequences by automatically calculating the frequency of nucleotides or amino acids in each sequence position and outputting those that occur under a user-specified frequency (default of p = 0.001). These results can then be used to explore fundamental population genetic and phylogeographic patterns, mechanisms and processes at the microevolutionary level, such as nucleotide and amino acid sequence conservation. Our package extends earlier work pertaining to an implementation of VLF analysis in Microsoft Excel, which was found to be both computationally slow and error prone. We compare those results to our own herein. Results between the two implementations are found to be highly consistent for a large DNA barcode dataset of bird species. Differences in results are readily explained by both manual human error and inadequate Linnean taxonomy (specifically, species synonymy). Here, VLF is also applied to a subset of avian barcodes to assess the extent of biological artifacts at the species level for Canada goose (Branta canadensis), as well as within a large dataset of DNA barcodes for fishes of forensic and regulatory importance. The novelty of VLF and its benefit over the previous implementation include its high level of automation, speed, scalability and ease-of-use, each desirable characteristics which will be extremely valuable as more sequence data are rapidly accumulated in popular reference databases, such as BOLD and GenBank.

Predicting Corynebacterium glutamicum promoters based on novel feature descriptor and feature selection technique

The promoter is an important noncoding DNA regulatory element, which combines with RNA polymerase to activate the expression of downstream genes. In industry, artificial arginine is mainly synthesized by Corynebacterium glutamicum. Replication of specific promoter regions can increase arginine production. Therefore, it is necessary to accurately locate the promoter in C. glutamicum. In the wet experiment, promoter identification depends on sigma factors and DNA splicing technology, this is a laborious job. To quickly and conveniently identify the promoters in C. glutamicum, we have developed a method based on novel feature representation and feature selection to complete this task, describing the DNA sequences through statistical parameters of multiple physicochemical properties, filtering redundant features by combining analysis of variance and hierarchical clustering, the prediction accuracy of the which is as high as 91.6%, the sensitivity of 91.9% can effectively identify promoters, and the specificity of 91.2% can accurately identify non-promoters. In addition, our model can correctly identify 181 promoters and 174 non-promoters among 400 independent samples, which proves that the developed prediction model has excellent robustness.

Quantifying Trade-Offs in the Choice of Ribosomal Barcoding Markers for Fungal Amplicon Sequencing: a Case Study on the Grapevine Trunk Mycobiome

The evolution of sequencing technology and multiplexing has rapidly expanded our ability to characterize fungal diversity in the environment. However, obtaining an unbiased assessment of the fungal community using ribosomal markers remains challenging. Longer amplicons were shown to improve taxonomic resolution and resolve ambiguities by reducing the risk of spurious operational taxonomic units. We examined the implications of barcoding strategies by amplifying and sequencing two ribosomal DNA fragments. We analyzed the performance of the full internal transcribed spacer (ITS) and a longer fragment including also a part of the 28S ribosomal subunit replicated on 60 grapevine trunk core samples. Grapevine trunks harbor highly diverse fungal communities with implications for disease development. Using identical handling, amplification, and sequencing procedures, we obtained higher sequencing depths for the shorter ITS amplicon. Despite the more limited access to polymorphism, the overall diversity in amplified sequence variants was higher for the shorter ITS amplicon. We detected no meaningful bias in the phylogenetic composition due to the amplicon choice across analyzed samples. Despite the increased resolution of the longer ITS-28S amplicon, the higher and more consistent yields of the shorter amplicons produced a clearer resolution of the fungal community of grapevine stem samples. Our study highlights that the choice of ribosomal amplicons should be carefully evaluated and adjusted according to specific goals. IMPORTANCE Surveying fungal communities is key to our understanding of ecological functions of diverse habitats. Fungal communities can inform about the resilience of agricultural ecosystems, risks to human health, and impacts of pathogens. Community compositions are typically analyzed using ribosomal DNA sequences. Due to technical limitations, most fungal community surveys were based on amplifying a short but highly variable fragment. Advances in sequencing technology enabled the use of longer fragments that can address some limitations of species identification. In this study, we examined the implications of choosing either a short or long ribosomal sequence fragment by replicating the analyses on 60 grapevine wood core samples. Using highly accurate long-read sequencing, we found that the shorter fragment produced substantially higher yields. The shorter fragment also revealed more sequence and species diversity. Our study highlights that the choice of ribosomal amplicons should be carefully evaluated and adjusted according to specific goals.

A method for quick and efficient identification of cichlid species by high resolution DNA melting analysis of minibarcodes

Freshwater bodies are key in supporting aquatic and terrestrial life. Ecological balance of freshwater habitats is very vulnerable, hence, often significantly disrupted by climatic changes and anthropogenic acts. In Israel, due to its relatively arid climate, many freshwater resources have been disrupted and still are under great pressure. The Sea of Galilee is the largest surface freshwater body in the Middle East and a habitat to unique populations of several fishes, including six cichlid species. Studies on the ecology of these fish and their conservation require effective monitoring tools. In this study, a simple and efficient molecular method was developed to identify the species of these lake cichlids using high resolution melting analysis of mini DNA barcodes. The species of an individual sample can be identified by a single tube PCR reaction. This assay successfully identified sequence differences both among and within species. Here, this method identified the species for 279 small cichlid fry that could not be morphologically identified, allowing to estimate relative species abundance and map their distribution in time and location. The results are key to understand not only the ecology of young stages but also their recruitment potential to adult fish populations and their sustainability. This method can be readily implemented in further ecological studies and surveys related to these species, in the lake and its surroundings, as a tool to enhance understanding and protection of these species.

Diagnosis of Mycoplasma hominis Meningitis with Metagenomic Next-Generation Sequencing: A Case Report

Background

Mycoplasma hominis meningitis is a rare postoperative complication of neurosurgery. Accurate and early diagnosis of M. hominis remains challenging because of the limitations of traditional detection methods. Metagenomic next-generation sequencing (mNGS) is an advanced technique with high sensitivity and specificity for identifying infectious pathogens; however, its application in diagnosing M. hominis meningitis has not been widely studied.

Case Presentation

We report the case of a 61-year-old man who presented with fever and headache after neurosurgical treatment for a cerebral hemorrhage. Empiric antibiotic therapy was ineffective. Traditional culture of pathogens and serological testing yielded negative results, but M. hominis was detected in the cerebrospinal fluid by mNGS. After further verification by polymerase chain reaction (PCR), the patient's clinical treatment was adjusted accordingly. With targeted antibiotic intervention, the patient's symptoms were effectively alleviated, and clinical indicators returned to normal levels. Furthermore, the abundance of M. hominis decreased significantly compared to the initial mNGS reading after targeted treatment, indicating that the infection caused by M. hominis was effectively controlled.

Conclusion

Using mNGS, we found that M. hominis may be a candidate causative agent of meningitis. The technique also has the advantage of timeliness and accuracy that traditional cultures cannot achieve. A combination of mNGS with PCR is recommended to identify pathogens in the early stages of infectious diseases to administer targeted clinical medication.

Two new species of Setostylus Matile, 1990 (Diptera: Keroplatidae) from China

In this study, two new species of Setostylus (Diptera: Keroplatidae: Keroplatinae), S. tridigitus sp. n. and S. triumphus sp. n. are described, with a key to all the species of the genus. Male habitus and images of diagnostic morphological characteristics are provided. Status of these two new species is also supported by the genetic distances and neighbor-joining (NJ) tree in the DNA barcode analysis.  

Transcriptome-wide measurement of poly(A) tail length and composition at subnanogram total RNA sensitivity by PAIso-seq

Poly(A) tails are added to the 3' ends of most mRNAs in a non-templated manner and play essential roles in post-transcriptional regulation, including mRNA export, stability and translation. Measuring poly(A) tails is critical for understanding their regulatory roles in almost every aspect of biological and medical studies. Previous methods for analyzing poly(A) tails require large amounts of input RNA (microgram-level total RNA), which limits their application. We recently developed a poly(A) inclusive full-length RNA isoform-sequencing method (PAIso-seq) at single-oocyte-level sensitivity (a single mammalian oocyte contains ~0.5 ng of total RNA) based on PacBio sequencing that enabled accurate measurement of the poly(A) tail length and non-A residues within the body of poly(A) tails along with the full-length cDNA, providing the opportunity to study precious in vivo samples with very limited input material. Here, we describe a detailed protocol for PAIso-seq library preparation from single mouse oocytes or bulk oocyte samples. In addition, we provide a complete bioinformatic pipeline to perform the analysis from the raw data to downstream analysis. The minimum time required is ~14.5 h for PAIso-seq double-stranded cDNA preparation, 2 d for PacBio sequencing in HiFi mode and 8 h for the initial data analysis.

Introduction to the principles and methods underlying the recovery of metagenome-assembled genomes from metagenomic data

The rise of metagenomics offers a leap forward for understanding the genetic diversity of microorganisms in many different complex environments by providing a platform that can identify potentially unlimited numbers of known and novel microorganisms. As such, it is impossible to imagine new major initiatives without metagenomics. Nevertheless, it represents a relatively new discipline with various levels of complexity and demands on bioinformatics. The underlying principles and methods used in metagenomics are often seen as common knowledge and often not detailed or fragmented. Therefore, we reviewed these to guide microbiologists in taking the first steps into metagenomics. We specifically focus on a workflow aimed at reconstructing individual genomes, that is, metagenome-assembled genomes, integrating DNA sequencing, assembly, binning, identification and annotation.

Towards Large-scale Integrative Taxonomy (LIT): resolving the data conundrum for dark taxa

New, rapid, accurate, scalable, and cost-effective species discovery and delimitation methods are needed for tackling “dark taxa,” here defined as groups for which \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{upgreek} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} }{}$<$\end{document}10\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{upgreek} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} }{}$\%$\end{document} of all species are described and the estimated diversity exceeds 1,000 species. Species delimitation for these taxa should be based on multiple data sources (“integrative taxonomy”) but collecting multiple types of data risks impeding a discovery process that is already too slow. We here develop large-scale integrative taxonomy (LIT), an explicit method where preliminary species hypotheses are generated based on inexpensive data that can be obtained quickly and cost-effectively. These hypotheses are then evaluated based on a more expensive type of “validation data” that is only obtained for specimens selected based on objective criteria applied to the preliminary species hypotheses. We here use this approach to sort 18,000 scuttle flies (Diptera: Phoridae) into 315 preliminary species hypotheses based on next-generation sequencing barcode (313 bp) clusters (using objective clustering [OC] with a 3\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{upgreek} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} }{}$\%$\end{document} threshold). These clusters are then evaluated with morphology as the validation data. We develop quantitative indicators for predicting which barcode clusters are likely to be incongruent with morphospecies by randomly selecting 100 clusters for in-depth validation with morphology. A linear model demonstrates that the best predictors for incongruence between barcode clusters and morphology are maximum p-distance within the cluster and a newly proposed index that measures cluster stability across different clustering thresholds. A test of these indicators using the 215 remaining clusters reveals that these predictors correctly identify all clusters that are incongruent with morphology. In our study, all morphospecies are true or disjoint subsets of the initial barcode clusters so that all incongruence can be eliminated by varying clustering thresholds. This leads to a discussion of when a third data source is needed to resolve incongruent grouping statements. The morphological validation step in our study involved 1,039 specimens (5.8\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{upgreek} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} }{}$\%$\end{document} of the total). The formal LIT protocol we propose would only have required the study of 915 (5.1\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{upgreek} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} }{}$\%$\end{document}: 2.5 specimens per species), as we show that clusters without signatures of incongruence can be validated by only studying two specimens representing the most divergent haplotypes. To test the generality of our results across different barcode clustering techniques, we establish that the levels of incongruence are similar across OC, Automatic Barcode Gap Discovery (ABGD), Poisson Tree Processes (PTP), and Refined Single Linkage (RESL) (used by Barcode of Life Data System to assign Barcode Index Numbers [BINs]). OC and ABGD achieved a maximum congruence score with the morphology of 89\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{upgreek} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} }{}$\%$\end{document} while PTP was slightly less effective (84\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{upgreek} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} }{}$\%$\end{document}). RESL could only be tested for a subset of the specimens because the algorithm is not public. BINs based on 277 of the original 1,714 haplotypes were 86\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{upgreek} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} }{}$\%$\end{document} congruent with morphology while the values were 89\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{upgreek} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} }{}$\%$\end{document} for OC, 74\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{upgreek} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} }{}$\%$\end{document} for PTP, and 72\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{upgreek} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} }{}$\%$\end{document} for ABGD. [Biodiversity discovery; dark taxa; DNA barcodes; integrative taxonomy.]

Message in a Bottle-Metabarcoding enables biodiversity comparisons across ecoregions

BACKGROUND

Traditional biomonitoring approaches have delivered a basic understanding of biodiversity, but they cannot support the large-scale assessments required to manage and protect entire ecosystems. This study used DNA metabarcoding to assess spatial and temporal variation in species richness and diversity in arthropod communities from 52 protected areas spanning 3 Canadian ecoregions.

RESULTS

This study revealed the presence of 26,263 arthropod species in the 3 ecoregions and indicated that at least another 3,000-5,000 await detection. Results further demonstrate that communities are more similar within than between ecoregions, even after controlling for geographical distance. Overall α-diversity declined from east to west, reflecting a gradient in habitat disturbance. Shifts in species composition were high at every site, with turnover greater than nestedness, suggesting the presence of many transient species.

CONCLUSIONS

Differences in species composition among their arthropod communities confirm that ecoregions are a useful synoptic for biogeographic patterns and for structuring conservation efforts. The present results also demonstrate that metabarcoding enables large-scale monitoring of shifts in species composition, making it possible to move beyond the biomass measurements that have been the key metric used in prior efforts to track change in arthropod communities.

A DNA barcode survey of insect biodiversity in Pakistan

Although Pakistan has rich biodiversity, many groups are poorly known, particularly insects. To address this gap, we employed DNA barcoding to survey its insect diversity. Specimens obtained through diverse collecting methods at 1,858 sites across Pakistan from 2010-2019 were examined for sequence variation in the 658 bp barcode region of the cytochrome c oxidase 1 (COI) gene. Sequences from nearly 49,000 specimens were assigned to 6,590 Barcode Index Numbers (BINs), a proxy for species, and most (88%) also possessed a representative image on the Barcode of Life Data System (BOLD). By coupling morphological inspections with barcode matches on BOLD, every BIN was assigned to an order (19) and most (99.8%) were placed to a family (362). However, just 40% of the BINs were assigned to a genus (1,375) and 21% to a species (1,364). Five orders (Coleoptera, Diptera, Hemiptera, Hymenoptera, Lepidoptera) accounted for 92% of the specimens and BINs. More than half of the BINs (59%) are so far only known from Pakistan, but others have also been reported from Bangladesh (13%), India (12%), and China (8%). Representing the first DNA barcode survey of the insect fauna in any South Asian country, this study provides the foundation for a complete inventory of the insect fauna in Pakistan while also contributing to the global DNA barcode reference library.

Complete chloroplast genome features of the model heavy metal hyperaccumulator Arabis paniculata Franch and its phylogenetic relationships with other Brassicaceae species

Arabis paniculata Franch (Brassicaceae) has been widely used for the phytoremediation of heavy mental, owing to its hyper tolerance of extreme Pb, Zn, and Cd concentrations. However, studies on its genome or plastid genome are scarce. In the present study, we obtained the complete chloroplast (cp) genome of A. paniculata via de novo assembly through the integration of Illumina reads and PacBio subreads. The cp genome presents a typical quadripartite cycle with a length of 153,541 bp, and contains 111 unigenes, with 79 protein-coding genes, 28 tRNAs and 4 rRNAs. Codon usage analysis showed that the codons for leucine were the most frequent codons and preferentially ended with A/U. Synonymous (Ks) and non-synonymous (Ka) substitution rate analysis indicated that the unigenes, ndhF and rpoC2, related to "NADH-dehydrogenase" and "RNA polymerase" respectively, underwent the lowest purifying selection pressure. Phylogenetic analysis demonstrated that Arabis flagellosa and A. hirsuta are more similar to each other than to A. paniculata, and Arabis is the closest relative of Draba among all Brassicaceae genera. These findings provide valuable information for the optimal exploitation of this model species as a heavy-metal hyperaccumulator.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s12298-022-01151-1.

Identifying cryptic fern gametophytes using DNA barcoding: A review

Ferns and lycophytes are unique among land plants in having sporophyte (diploid) and gametophyte (haploid) generations that can grow independently of each other. While most studies of fern ecology focus on the more visible sporophytic stage, the gametophyte is critically important, as it is the sexual phase of the life cycle. Yet, fern gametophytes have long been neglected in field studies due to their small size and cryptic morphology. DNA barcoding is a powerful method that can be used to identify field-collected gametophytes to species and allow for detailed study of their ecology. Here, we review the state of DNA barcoding as applied to fern gametophytes. First, we trace the history of DNA barcoding and how it has come to be applied to fern gametophytes. Next, we summarize case studies that show how DNA barcoding has been used to better understand fern species distributions, gametophyte ecology, and community ecology. Finally, we propose avenues for future research using this powerful tool, including next-generation DNA sequencing for in-field identification of cryptic gametophytes.

Unearthing soil arthropod diversity through DNA metabarcoding

DNA metabarcoding has the potential to greatly advance understanding of soil biodiversity, but this approach has seen limited application for the most abundant and species-rich group of soil fauna-the arthropods. This study begins to address this gap by comparing information on species composition recovered from metabarcoding two types of bulk samples (specimens, soil) from a temperate zone site and from bulk soil samples collected at eight sites in the Arctic. Analysis of 22 samples (3 specimen, 19 soil) revealed 410 arthropod OTUs belonging to 112 families, 25 orders, and nine classes. Studies at the temperate zone site revealed little overlap in species composition between soil and specimen samples, but more overlap at higher taxonomic levels (families, orders) and congruent patterns of α- and β-diversity. Expansion of soil analyses to the Arctic revealed locally rich, highly dissimilar, and spatially structured assemblages compatible with dispersal limited and environmentally driven assembly. The current study demonstrates that DNA metabarcoding of bulk soil enables rapid, large-scale assessments of soil arthropod diversity. However, deep sequence coverage is required to adequately capture the species present in these samples, and expansion of the DNA barcode reference library is necessary to improve taxonomic resolution of the sequences recovered through this approach.

Peering into the Darkness: DNA Barcoding Reveals Surprisingly High Diversity of Unknown Species of Diptera (Insecta) in Germany

Determining the size of the German insect fauna requires better knowledge of several megadiverse families of Diptera and Hymenoptera that are taxonomically challenging. This study takes the first step in assessing these “dark taxa” families and provides species estimates for four challenging groups of Diptera (Cecidomyiidae, Chironomidae, Phoridae, and Sciaridae). These estimates are based on more than 48,000 DNA barcodes (COI) from Diptera collected by Malaise traps that were deployed in southern Germany. We assessed the fraction of German species belonging to 11 fly families with well-studied taxonomy in these samples. The resultant ratios were then used to estimate the species richness of the four “dark taxa” families (DT families hereafter). Our results suggest a surprisingly high proportion of undetected biodiversity in a supposedly well-investigated country: at least 1800–2200 species await discovery in Germany in these four families. As this estimate is based on collections from one region of Germany, the species count will likely increase with expanded geographic sampling.