Comparative antennal transcriptome of Apis cerana cerana from four developmental stages

Transcriptome-wide analysis uncovers regulatory elements of the antennal transcriptome repertoire of bumblebee at different life stages

Bumblebees are crucial pollinators, providing essential ecosystem services and global food production. The success of pollination services relies on the interaction between sensory organs and the environment. The antenna functions as a versatile multi-sensory organ, pivotal in mediating chemosensory/olfactory information, and governs adaptive responses to environmental changes. Despite an increasing number of RNA-sequencing studies on insect antenna, comprehensive antennal transcriptome studies at the different life stages were not elucidated systematically. Here, we quantified the expression profile and dynamics of coding/microRNA genes of larval head and antennal tissues from early- and late-stage pupa to the adult of Bombus terrestris as suitable model organism among pollinators. We further performed Pearson correlation analyses on the gene expression profiles of the antennal transcriptome from larval head tissue to adult stages, exploring both positive and negative expression trends. The positively correlated coding genes were primarily enriched in sensory perception of chemical stimuli, ion transport, transmembrane transport processes and olfactory receptor activity. Negatively correlated genes were mainly enriched in organic substance biosynthesis and regulatory mechanisms underlying larval body patterning and the formation of juvenile antennal structures. As post-transcriptional regulators, miR-1000-5p, miR-13b-3p, miR-263-5p and miR-252-5p showed positive correlations, whereas miR-315-5p, miR-92b-3p, miR-137-3p, miR-11-3p and miR-10-3p exhibited negative correlations in antennal tissue. Notably, based on the inverse expression relationship, positively and negatively correlated microRNA (miRNA)-mRNA target pairs revealed that differentially expressed miRNAs predictively targeted genes involved in antennal development, shaping antennal structures and regulating antenna-specific functions. Our data serve as a foundation for understanding stage-specific antennal transcriptomes and large-scale comparative analysis of transcriptomes in different insects.

Isolation of the AccCDK8 gene of Apis cerana cerana and its functional analysis under pesticide and heavy metal stress

Environmental pollution has gained negative attention in recent years. The pesticides and heavy metals are top list of environmental toxicants directly endangering the survival and development of Apis cerana cerana. Cyclin-dependent kinases (CDKs) are heteromeric serine/threonine kinases that participate in cell cycle regulation and have a vital role in pesticide and heavy metal stress in Apis cerana cerana. In this experiment, we filtered out CDK8 gene from Apis cerana cerana (AccCDK8) and investigated its functions of pesticide and heavy metals resistance. Sequence analysis indicated that AccCDK8 is highly homologous to multiple CDK8s and contains a highly conserved CDK active site sequence. Phylogenetic analysis showed that AmCDK8 and AccCDK8 were closely related evolutionarily in Apis mellifera. Transcriptome analysis revealed that AccCDK8 expression was differentially affected after exposure to pesticide and heavy metal stresses. This indicates that AccCDK8 has a significant role in the resistance of Apis cerana cerana to pesticide and heavy metal stresses. It has implications for studying the function of CDK in other insects in response to stress.

Functional analysis of AccCDK2-like and AccCINP-like genes in Apis cerana cerana under pesticide and heavy metal stress

Heavy metals and pesticides represent prominent sources of pollution in the natural habitat of Apis cerana cerana, potentially endangering their health through the induction of oxidative stress reactions. This study aimed to address this issue by isolating AccCDK2-like and AccCINP-like proteins from Apis cerana cerana and investigating their functional roles in honey bee resistance against pesticide and heavy metal stresses. Bioinformatics analysis revealed significant homology of these proteins with those found in other species. Functional studies confirmed their participation in interaction with each other, alongside demonstrating distinct patterns of expression and localization. Specifically, AccCDK2-like exhibited higher expression levels in prepupae and muscle tissues, while AccCINP-like showed maximal expression in brown pupae and abdomen. Furthermore, the expression levels of these proteins were found to be modulated in response to pesticide and heavy metal stresses. Notably, overexpression of AccCDK2-like and AccCINP-like led to a noticeable alteration in E. coli's ability to withstand external stresses. Additionally, silencing of the AccCDK2-like and AccCINP-like genes resulted in a significant reduction in antioxidant enzyme activity and the expression levels of genes related to antioxidant function. Consequently, the mortality rate of Apis cerana cerana under pesticide and heavy metal stresses conspicuously increased. Hence, our findings suggest that AccCDK2-like and AccCINP-like proteins potentially play a crucial role in the response of Apis cerana cerana to pesticide and heavy metal stress, likely by modulating the antioxidant pathway.

AccsHSP21.7 enhances the antioxidant capacity of Apis cerana cerana

BACKGROUND

The widespread use of glyphosate has many adverse effects on Apis cerana cerana. Due to the incomplete understanding of the molecular mechanisms of glyphosate toxicity, there are no available methods for mitigating the threat of glyphosate to Apis cerana cerana. Small heat shock proteins (sHSPs) play an important role in resisting oxidative stress, but their mechanism of action in Apis cerana cerana remains unclear.

RESULTS

In this experiment, we cloned and identified AccsHSP21.7. Studies have shown that AccsHSP21.7 contains binding motifs for various transcription factors related to oxidative stress. Abiotic stresses induced the expression of AccsHSP21.7. Bacteriostatic testing of a recombinant AccsHSP21.7 protein proved that Escherichia coli overexpressing AccsHSP21.7 showed increased resistance to oxidative stress. Knocking down the AccsHSP21.7 gene caused significant damage to midgut cells, which seriously disrupted the antioxidant system in Apis cerana cerana and greatly increased mortality under glyphosate stress.

CONCLUSION

This study investigated the relationship between antioxidant regulation and the AccsHSP21.7 gene at the molecular level, and the results have guiding significance for the improvement of stress resistance in Apis cerana cerana. © 2023 Society of Chemical Industry.

Characterization of the RACK1 gene of Aips cerana cerana and its role in adverse environmental stresses

Receptors for Activated C Kinase 1 (RACK1s) are a kind of multifunction scaffold protein that plays an important role in cell signal transductions and animal development. However, the function of RACK1 in the Chinese honeybee Apis cerana cerana is little known. Here, we isolated and identified a RACK1 gene from Apis cerana cerana, named AccRACK1. By bioinformatic analysis, we revealed a high nucleic acid homology between AccRACK1 and RACK1 of Apis cerana. RT-qPCR analyses demonstrated AccRACK1 was mostly expressed in 3rd instar larvae, darked-eyed pupae and adults (one and thirty days post-emergence), suggesting it might participate in the development of A. cerana cerana. Moreover, the expression of AccRACK1 was highest in the thorax, followed by the venom gland. Compared to the blank control group, AccRACK1 was induced by 24 and 44 °C, HgCl2 and pesticides (paraquat, pyridaben and methomyl) but inhibited by 14 °C, H2O2, UV light and cyhalothrin. Additionally, 0.05, 0.1, 1, 5 and 10 mg/ml PPN (juvenile hormone analogue pyriproxyfen) could promote the expression of AccRACK1, with 1 mg/ml showing the highest upregulation, suggesting it was regulated by hormones. Further study found that after knockdown of AccRACK1 by RNAi, the expression of the eukaryotic initiation factor 6 of A. cerana cerana (AcceIF6), an initiation factor regulating the initiation of translation, was inhibited, indicating AccRACK1 might affect cellular responses by translation. These findings, taken together, suggest AccRACK1 is involved in the development and responses to abiotic stresses of A. cerana cerana, and therefore, it may be of critical importance to the survival of A. cerana cerana.

Transcriptome profiling of venom gland from wasp species: de novo assembly, functional annotation, and discovery of molecular markers

Background

Vespa velutina, one of the most aggressive and fearful wasps in China, can cause grievous allergies and toxic reactions, leading to organ failure and even death. However, there is little evidence on molecular data regarding wasps. Therefore, we aimed to provide an insight into the transcripts expressed in the venom gland of wasps.

Results

In our study, high-throughput RNA sequencing was performed using the venom glands of four wasp species. First, the mitochondrial cytochrome C oxidase submit I (COI) barcoding and the neighbor joining (NJ) tree were used to validate the unique identity and lineage of each individual species. After sequencing, a total of 127,630 contigs were generated and 98,716 coding domain sequences (CDS) were predicted from the four species. The Gene ontology (GO) enrichment analysis of unigenes revealed their functional role in important biological processes (BP), molecular functions (MF) and cellular components (CC). In addition, c-type, p1 type, p2 type and p3 type were the most commonly found simple sequence repeat (SSR) types in the four species of wasp transcriptome. There were differences in the distribution of SSRs and single nucleotide polymorphisms (SNPs) among the four wasp species.

Conclusions

The transcriptome data generated in this study will improve our understanding on bioactive proteins and venom-related genes in wasp venom gland and provide a basis for pests control and other applications. To our knowledge, this is the first study on the identification of large-scale genomic data and the discovery of microsatellite markers from V. tropica ducalis and V. analis fabricius.

Insect Mouthpart Transcriptome Unveils Extension of Cuticular Protein Repertoire and Complex Organization

Insects have developed intriguing cuticles with very specific structures and functions, including microstructures governing their interactions with transmitted microbes, such as in aphid mouthparts harboring virus receptors within such microstructures. Here, we provide the first transcriptome analysis of an insect mouthpart cuticle (“retort organs” [ROs], the stylets' precursors). This analysis defined stylets as a complex composite material. The retort transcriptome also allowed us to propose an algorithmic definition of a new cuticular protein (CP) family with low complexity and biased amino acid composition. Finally, we identified a differentially expressed gene encoding a pyrokinin (PK) neuropeptide precursor and characterizing the mandibular glands. Injection of three predicted synthetic peptides PK1/2/3 into aphids prior to ecdysis caused a molt-specific phenotype with altered head formation. Our study provides the most complete description to date of the potential protein composition of aphid stylets, which should improve the understanding of the transmission of stylet-borne viruses.

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First transcriptome of aphid retort glands and stylet cuticular protein composition

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A pyrokinin transcript is mandibular gland specific at the onset of adult moult

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Stylet cuticle is of higher protein complexity than other insect cuticles

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A new class of low-complexity cuticular proteins is predicted

Comparisons of lung and gluteus transcriptome profiles between yaks at different ages

The yak, Bos grunniens, is the only large mammal in the Qinghai-Tibet Plateau and has been bred to provide meat, milk, and transportation. Previous studies indicate that the immune system contributes to the yak's adaptation to high-altitude environments. In order to further investigate changes in immune function during yak development, we compared the transcriptome profiles of gluteus and lung tissues among yaks at 6, 30, 60, and 90 months of age. Analyses of significantly differentially expressed genes (DEGs) in lung tissues revealed that immune function was more activated at 6-months and less activated at 90-months than in the 30 and 60-month-old animals. DEG exploration in gluteal tissues revealed that immune functions were more highly activated at both 6 and 90-months, compared with 30 and 60-months. Immune system activation in the muscle and lung tissues of 30-month-old yaks may increase their resistance to infections, while decreased may be due to aging. Furthermore, the higher immune activation status in the gluteal tissues in 90-month-old yaks could be due to muscle injury and subsequent regeneration, which is supported by the fact that 5 unigenes related with muscle injury and 3 related to muscle regeneration displayed greater expression levels at 90-months than at 30 and 60-months. Overall, the present study highlights the important role of the immune system in yak development, which will facilitate future investigations.