Digital Gene Expression analysis in the midgut of 4008 silkworm strain infected with cytoplasmic polyhedrosis virus

Identification of Key Genes Involved in Resistance to Early Stage of BmNPV Infection in Silkworms

Bombyx mori nucleopolyhedrovirus (BmNPV) is one of the most serious pathogens restricting the sustainable development of the sericulture industry. Currently, there is no effective treatment for BmNPV infection in silkworms, and the mechanism underlying BmNPV resistance in silkworms is also not clear. In this study, comparative transcriptome analyses were carried out in midguts of two silkworm varieties, namely BaiyuN, which is a resistance variety, and Baiyu, which is a susceptible variety, at five different time points (i.e., 0, 1, 3, 6, and 9 h) post-BmNPV infection to detect the early-stage transcriptional changes in these silkworms. In total, 1911 and 1577 differentially expressed genes (DEGs) were identified in the Baiyu and BaiyuN varieties, respectively, involving a total of 48 metabolic pathways. Of these pathways, eight were shared by the Baiyu and BaiyuN varieties in response to BmNPV infection. Notably, four genes (i.e., BGIBMGA08815, BGIBMGA003935, BGIBMGA003571, BGIBMGA010059) were upregulated in the Baiyu variety while downregulated in the BaiyuN variety. The inhibited expression of these four genes in the resistant variety highlighted their potential roles in the resistance of early-stage viral replication. Thus, our study provided a new avenue for the further study of the mechanism underlying BmNPV infection in silkworms and the potential treatment of BmNPV infection.

Transcriptional responses of Daphnis nerii larval midgut to oral infection by Daphnis nerii cypovirus-23

BACKGROUND

Daphnis nerii cypovirus-23 (DnCPV-23) is a new type of cypovirus and has a lethal effect on the oleander hawk moth, Daphnis nerii which feeds on leave of Oleander and Catharanthus et al. After DnCPV-23 infection, the change of Daphnis nerii responses has not been reported.

METHODS

To better understand the pathogenic mechanism of DnCPV-23 infection, 3rd-instar Daphnis nerii larvae were orally infected with DnCPV-23 occlusion bodies and the transcriptional responses of the Daphnis nerii midgut were analyzed 72 h post-infection using RNA-seq.

RESULTS

The results showed that 1979 differentially expressed Daphnis nerii transcripts in the infected midgut had been identified. KEGG analysis showed that protein digestion and absorption, Toll and Imd signaling pathway were down-regulated. Based on the result, we speculated that food digestion and absorption in insect midgut might be impaired after virus infection. In addition, the down-regulation of the immune response may make D. nerii more susceptible to bacterial infections. Glycerophospholipid metabolism and xenobiotics metabolism were up-regulated. These two types of pathways may affect the viral replication and xenobiotic detoxification of insect, respectively.

CONCLUSION

These results may facilitate a better understanding of the changes in Daphnis nerii metabolism during cypovirus infection and serve as a basis for future research on the molecular mechanism of DnCPV-23 invasion.

Host Response against Virus Infection in an Insect: Bidensovirus Infection Effect on Silkworm (Bombyx mori)

Silk cocoons obtained from silkworms are the primary source of commercial silk, making the silkworm an economically important insect. However, the silk industry suffers significant losses due to various virus infections. Bombyx mori bidensovirus (BmBDV) is one of the pathogens that cause flacherie disease in silkworms. Most silkworm strains die after BmBDV infection. However, certain silkworm strains show resistance to the virus, which is determined by a single recessive gene, nsd-2. The +^nsd-2 gene (allele of nsd-2; the susceptibility gene) encodes a putative amino acid transporter expressed only in the insect’s midgut, where BmBDV can infect, suggesting that this membrane protein may function as a receptor for BmBDV. Interestingly, the expression analysis revealed no changes in the +^nsd-2 gene expression levels in virus-uninfected silkworms, whereas the gene expression drastically decreased in the virus-infected silkworm. This condition indicates that the host factor’s expression, the putative virus receptor, is affected by BmBDV infection. It has recently been reported that the expression levels of some host genes encoding cuticle, antioxidant, and immune response-related proteins were significantly regulated by BmBDV infection. In this review, we discuss the host response against virus infection based on our knowledge and long-term research experience in this field.

Characterization of sediment toxicity in Shanghai Harbor using toxicity tests and digital gene expression analysis based on clams Ruditapes phillipinarum

In the present study, chemical analysis of contaminants (three classes of organic pollutants and seven metals) and elutriate toxicity test were adopted to evaluate the potential environmental hazards of dredged sediment samples from five sites (SS1-5) along Huangpu River Channel (Shanghai Harbor, China). The metal Pb, Cu, Cr, Zn and the organic pollutants including total hexachlorocyclohexane (HCHs) and total dichlorodiphenyltrichloroethane (DDTs) in the five samples exceeded the threshold for effects level (TEL) to varying degrees. The probable effect concentration quotients (Q_PECm) of contaminants from the five dredged samples were all above 0.25, which means potential toxicity risks. Elutriate toxicity tests using medaka fish (Oryzias melastigma) and manila clam (Ruditapes philippinarum) showed that SS2 caused mortality to both species and SS1 caused mortality to fish. To explore the molecular biomarkers that may reflect the toxic effects, differential expressed genes were identified by RNA-Seq-based transcriptome profiling from the survived clams exposed to the two polluted elutriates (SS1, SS2). In clams exposed to SS1 and SS2 elutriate, 368 and 860 differential expressed genes (DEGs) were up-regulated, 199 and 1304 genes were down-regulated, respectively. Fourteen DEGs were selected from the enriched pathways that reflect cytotoxicity and responses to xenobiotics for the following quantitative real time PCR analysis. The transcriptomic profiling and the selected gene's expression patterns from clams exposed to SS1 and SS2 showed significant differences with the non-contaminated and control groups. Using the expression data of the selected gene battery in Factor Analysis allowed the discrimination between contaminated and non-contaminated sites and may reflect an influence gradient of sites. The development of the assay of these molecular biomarkers may provide a rapid and high-throughput tool for the quality assessment of the dredging sediments.

Antimicrobial Peptides as Potential Antiviral Factors in Insect Antiviral Immune Response

Antimicrobial peptides (AMPs) with antiviral activity (antiviral peptides: AVPs) have become a research hotspot and already show immense potential to become pharmaceutically available antiviral drugs. AVPs have exhibited huge potential in inhibiting viruses by targeting various stages of their life cycle. Insects are the most speciose group of animals that inhabit almost all ecosystems and habitats on the land and are a rich source of natural AMPs. However, insect AVP mining, functional research, and drug development are still in their infancy. This review aims to summarize the currently validated insect AVPs, explore potential new insect AVPs and to discuss their possible mechanism of synthesis and action, with a view to providing clues to unravel the mechanisms of insect antiviral immunity and to develop insect AVP-derived antiviral drugs.

Antiviral defense against Cypovirus 1 (Reoviridae) infection in the silkworm, Bombyx mori

Recent years have shown a large increase in studies of infection of the silkworm (Bombyx mori) with Cypovirus 1 (previously designated as B. mori cytoplasmic polyhedrosis virus), that causes serious damage in sericulture. Cypovirus 1 has a single-layered capsid that encapsulates a segmented double-strand RNA (dsRNA) genome which are attractive features for the establishment of a biotechnological platform for the production of specialized gene silencing agents, either as recombinant viruses or as viral-like particles with nonreplicative dsRNA cargo. For both combatting viral disease and application of Cypovirus-based pest control, however, a better understanding is needed of the innate immune response caused by Cypovirus infection of the midgut of lepidopteran larvae. Studies of deep sequencing of viral small RNAs have indicated the importance of the RNA interference pathway in the control of Cypovirus infection although many functional aspects still need to be elucidated and conclusive evidence is lacking. A considerable number of transcriptome studies were carried out that revealed a complex response that hitherto remains uncharacterized because of a dearth in functional studies. Also, the uptake mechanism of Cypovirus by the midgut cells remains unclarified because of contrasting mechanisms revealed by electron microscopy and functional studies. The field will benefit from an increase in functional studies that will depend on transgenic silkworm technology and reverse genetics systems for Cypovirus 1.

Discovery of anti-viral molecules and their vital functions in Bombyx mori

The silkworm Bombyx mori (B. mori), a lepidopteran model organism, has become an important model for molecular biology researches with its genome completely sequenced. Silkworms confront different types of virus diseases, mainly including those caused by Bombyx mori nucleopolyhedrovirus (BmNPV), Bombyx mori densovirus type 1 (BmDNV-1), Bombyx mori bidesovirus (BmBDV) which was termed as Bombyx mori densovirus type 2 (BmDNV-2) or Bombyx mori parvo-like virus (BmPLV) before in sericulture. B. mori offers excellent models to study the molecular mechanisms of insect innate immune responses to viruses. A variety of molecules and pathways have been identified to be involved in the immune responses in the silkworm to viruses, such as the antimicrobial peptides, prophenoloxidase-activating system, apoptosis, ROS, small RNA and related molecules. Here in this review, we summarize the current research advances in molecules involved in silkworm anti-virus pathways. Moreover, taking BmNPV as an example, we proposed a schematic model of molecules and pathways involved in silkworm immune responses against virus infection. We hope this review can facilitate further study of antiviral mechanisms in silkworm, and provide a reference for virus diseases in other organisms.

Identification and characterization of circular RNAs in the silkworm midgut following Bombyx mori cytoplasmic polyhedrosis virus infection

The pathogenesis of Bombyx mori cytoplasmic polyhedrosis virus (BmCPV) infection is unclear, although accumulating evidence indicates that circular RNAs (circRNAs), which act as competing endogenous RNAs or positive regulators, play important roles in regulating gene expression in eukaryotes and, thus, may play a role in BmCPV infections. To explore the expression and biological functions of circRNAs in the silkworm midgut following BmCPV infection, silkworm circRNA expression profiles of normal midgut tissue (control) and BmCPV-infected midgut tissue (test) were determined using high-through sequencing. A total of 9,753 and 7,475circRNAs were detected from the control and test samples, respectively. The two samples shared 6,085 circRNAs, while 646 and 737 circRNAs were expressed specifically in the control and test samples, respectively. A total of 3,638 circRNAs were shown to be differentially expressed, and 400 circRNAs were substantially differentially expressed with a fold-change ≥ 2.0 (p< 0.05 and a false discover rate < 0.05), of which 294 were up-regulated and 106 were down-regulated following infection. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses were conducted to determine the principal functions of the substantially differentially regulated genes. circRNA-miRNA interaction networks were constructed based on a correlation analysis between the differentially expressed circRNAs and the nature of their microRNA (miRNA) binding sites. The network inferred that 13 miRNAs interacting with 193 circRNAs were among the 300 most abundant relationships. bmo-miR-3389-5p, bmo-miR-745-3p, and bmo-miR-3262 were related to 30, 34, and 34 circRNAs, respectively. circRNA_8115, circRNA_9444, circRNA_4553, circRNA_0827, and circRNA_6649 contained six, five, four, four, and four miRNA binding sites, respectively. We further found that alternative circularization of circRNAs is a common feature in silkworms and that the junction sites of many silkworm circRNAs are flanked by canonical GT/AG splicing signals. Our study is the first to show the circRNA response to virus infection. Thus, it provides a novel perspective on circRNA-miRNA interactions during BmCPV pathogenesis, and it lays the foundation for future research of the potential roles of circRNAs in BmCPV pathogenesis.

Transcriptome Analysis of the Midgut of the Chinese Oak Silkworm Antheraea pernyi Infected with Antheraea pernyi Nucleopolyhedrovirus

The Antheraea pernyi nucleopolyhedrovirus (ApNPV) is an exclusive pathogen of A. pernyi. The intense interactions between ApNPV and A. pernyi cause a series of physiological and pathological changes to A. pernyi. However, no detailed report exists regarding the molecular mechanisms underlying the interactions between ApNPV and A. pernyi. In this study, four cDNA libraries of the A. pernyi midgut, including two ApNPV-infected groups and two control groups, were constructed for transcriptomic analysis to provide new clues regarding the molecular mechanisms that underlie these interactions. The transcriptome of the A. pernyi midgut was de novo assembled using the Trinity platform because of the lack of a genome resource for A. pernyi. Compared with the controls, a total of 5,172 differentially expressed genes (DEGs) were identified, including 2,183 up-regulated and 2,989 down-regulated candidates, of which 2,965 and 911 DEGs were classified into different GO categories and KEGG pathways, respectively. The DEGs involved in A. pernyi innate immunity were classified into several categories, including heat-shock proteins, apoptosis-related proteins, serpins, serine proteases and cytochrome P450s. Our results suggested that these genes were related to the immune response of the A. pernyi midgut to ApNPV infection via their essential roles in regulating a variety of physiological processes. Our results may serve as a basis for future research not only on the molecular mechanisms of ApNPV invasion but also on the anti-ApNPV mechanism of A. pernyi.

Gut immunity in Lepidopteran insects

Lepidopteran insects constitute one of the largest fractions of animals on earth, but are considered pests in their relationship with man. Key to the success of this order of insects is its ability to digest food and absorb nutrition, which takes place in the midgut. Because environmental microorganisms can easily enter Lepidopteran guts during feeding, the innate immune response guards against pathogenic bacteria, virus and microsporidia that can be devoured with food. Gut immune responses are complicated by both resident gut microbiota and the surrounding peritrophic membrane and are distinct from immune responses in the body cavity, which depend on the function of the fat body and hemocytes. Due to their relevance to agricultural production, studies of Lepidopteran insect midgut and immunity are receiving more attention, and here we summarize gut structures and functions, and discuss how these confer immunity against different microorganisms. It is expected that increased knowledge of Lepidopteran gut immunity may be utilized for pest biological control in the future.

Transcriptome analysis of interactions between silkworm and cytoplasmic polyhedrosis virus

Bombyx mori cytoplasmic polyhedrosis virus (BmCPV) specifically infects silkworm midgut (MG) and multiplication occurs mainly in posterior midgut (PM). In this study, MG and fat body (FB) were extracted at 0, 3, 24, and 72 h after BmCPV infection. The total sequence reads of each sample were more than 1510000, and the mapping ratio exceeded 95.3%. Upregulated transcripts increased in MG during the infection process. Gene ontology (GO) categories showed that antioxidants were all upregulated in FB but not in MG. BGI001299, BGI014434, BGI012068, and BGI009201 were MG-specific genes with transmembrane transport function, the expression of which were induced by BmCPV. BGI001299, BGI014434, and BGI012068 expressed in entire MG and may be involved in BmCPV invasion. BGI009201 expressed only in PM and may be necessary for BmCPV proliferation. BmPGRP-S2 and BGI012452 (a putative serine protease) were induced by BmCPV and may be involved in immune defense against BmCPV. The expression level of BmCPV S1, S2, S3, S6, and S7 was high and there was no expression of S9 in MG 72 h, implying that the expression time of structural protein coding genes is earlier. These results provide insights into the mechanism of BmCPV infection and host defense.

Genome-Wide Analysis of Host Responses to Four Different Types of Microorganisms in Bombyx Mori (Lepidoptera: Bombycidae)

Several pathogenic microorganisms have been used to investigate the genome-wide transcriptional responses of Bombyx mori to infection. However, studies have so far each focused on one microorganism, and systematic genome-wide comparison of transcriptional responses to different pathogenic microorganisms has not been undertaken. Here, we surveyed transcriptional responses of B. mori to its natural bacterial, viral, and fungal pathogens, Bacillus bombyseptieus, B. mori nucleopolyhedrovirus (BmNPV), and Beauveria bassiana, respectively, and to nonpathogenic Escherichia coli, by microarray analysis. In total, the expression of 2,436, 1,804, 1,743, and 912 B. mori genes was modulated by infection with B. bombyseptieus, BmNPV, B. bassiana, and E. coli, respectively. Notably, the expression of 620, 400, 177, or 165 of these genes was only modulated by infection with B. bombyseptieus, BmNPV, B. bassiana, or E. coli, respectively. In contrast to the expression of genes related to juvenile hormone synthesis and metabolism, that of genes encoding juvenile hormone binding proteins was microorganism-specific. Three basal metabolic pathways were modulated by infection with any of the four microorganisms, and 3, 14, 5, and 2 metabolic pathways were specifically modulated by infection with B. bombyseptieus, BmNPV, B. bassiana, and E. coli, respectively. Interestingly, BmNPV infection modulated the JAK/STAT signaling pathway, whereas both the Imd and Toll signaling pathways were modulated by infection with B. bombyseptieus, B. bassiana, or E. coli These results elucidate potential molecular mechanisms of the host response to different microorganisms, and provide a foundation for further work on host-pathogen interaction.

Nucleopolyhedrovirus infection and/or parasitism by Microplitis pallidipes Szepligeti affect hemocyte apoptosis of Spodoptera exigua (Hübner) larvae

We determined the effects of parasitism by the endoparasitoid Microplitis pallidipes Szepligeti and/or nucleopolyhedrovirus (NPV) infection on hemocyte apoptosis of Spodoptera exigua (Hübner) larvae. Compared to healthy (control) larvae, larvae that were parasitized, virus-infected, or both all showed a significant increase in hemocyte apoptosis during 48-h observation period. The peaks of hemocyte apoptosis in parasitized, virus-infected and parasitized+infected larvae were at 12, 24 and 48 h after treatment, and were 86.7±1.9, 87.4±3.6 and 76.5±1.6%, respectively. Meanwhile, compared to parasitized larvae, hemocyte apoptosis in jointly parasitized and infected larvae increased by 12.9%, 18.7% and 2.8% at 8, 36 and 48 h respectively, and decreased by 39.0% and 9.1% at 12 and 24h. Compared to virus-infected larvae, hemocyte apoptosis in jointly parasitized and infected larvae increased by 13.4%, 2.4% and 15.3% at 8, 36 and 48 h, respectively, and decreased by 4.0% and 29.9% at 12 and 24h. Our study found that joint and separate parasitism and SeNPV infection induced hemocyte apoptosis of S. exigua larvae. It also revealed that NPV infection promoted host hemocyte apoptosis induced by parasitism at early egg and larval stages of M. pallidipes in host larvae, but inhibited the same effect at late egg stage of M. pallidipes in host larvae, and that parasitism promoted host hemocyte apoptosis induced by NPV infection at early egg and larval stages of M. pallidipes in host larvae, but inhibited the same effect at late egg stage of M. pallidipes in host larvae.

Digital gene expression analysis of Helicoverpa armigera in the early stage of infection with Helicoverpa armigera nucleopolyhedrovirus

Helicoverpa armigera single nucleocapsid nucleopolyhedrovirus (HearNPV) is an obligatory and lethal parasite of the cotton bollworm and has been extensively used in China for the control of this notorious pest. Digital gene expression (DGE) analysis was adopted for an overall comparison of transcriptome profiling between HearNPV-infected and control healthy Helicoverpa armigera larvae during an early stage post-inoculation. A total of 908 differentially expressed genes (DEGs) were identified, of which 136 were up-regulated and 597 were down-regulated. GO category and KEGG pathway analysis demonstrated that the identified DEGs involved in ribosome biogenesis, aminoacyl-tRNA biosynthesis, protein processing in endoplasmic reticulum, biosynthesis of valine, leucine, isoleucine and the spliceosome were significantly down-regulated, whereas genes involved in pancreatic secretion, protein digestion and absorption and salivary secretion showed obviously up-regulated transcription. The DEGs were verified by quantitative real-time PCR, and genes that participated in defensive response, nutritional digestion and developmental regulation exhibited specific expression patterns in a continuous time-course assessment. These results provide basic data for future research on the molecular mechanism of HearNPV infection and the interactions between lepidopteran hosts and their specific NPV parasites.

Proteomics analysis of digestive juice from silkworm during Bombyx mori nucleopolyhedrovirus infection

Previous studies have analyzed the midgut transcriptome and proteome after challenge with Bombyx mori nucleopolyhedrovirus (BmNPV), however little information is available on the digestive juice proteome after BmNPV challenge. This study investigated BmNPV infection-induced protein changes in the digestive juice of silkworms using shotgun proteomics and MS sequencing. From the digestive juice of normal third-day, fifth-instar silkworm larvae, 75 proteins were identified, 44 of which were unknown; from larvae 6 h after inoculation with BmNPV, 106 proteins were identified, of which 39 were unknown. After BmNPV challenge, more secreted proteins appeared that had antiviral and digestive features. GO annotation analysis clustered most proteins in the lumen into catalytic, binding, and metabolic processes. Numerous proteins were reported to have BmNPV interactions. Hsp70 protein cognate, lipase-1, and chlorophyllide A-binding protein precursor were upregulated significantly after BmNPV challenge. Levels of trypsin-like serine protease, beta-1,3-glucanase, catalase, and serine protease transcripts decreased or were not significantly change after BmNPV challenge. Taken together, these findings provided insights into the interaction between host and BmNPV and revealed potential functions of digestive juice after per os BmNPV infection.

The gene expression profile of resistant and susceptible Bombyx mori strains reveals cypovirus-associated variations in host gene transcript levels

High-throughput paired-end RNA sequencing (RNA-Seq) was performed to investigate the gene expression profile of a susceptible Bombyx mori strain, Lan5, and a resistant B. mori strain, Ou17, which were both orally infected with B. mori cypovirus (BmCPV) in the midgut. There were 330 and 218 up-regulated genes, while there were 147 and 260 down-regulated genes in the Lan5 and Ou17 strains, respectively. Gene ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment for differentially expressed genes (DEGs) were carried out. Moreover, gene interaction network (STRING) analyses were performed to analyze the relationships among the shared DEGs. Some of these genes were related and formed a large network, in which the genes for B. mori cuticular protein RR-2 motif 123 (BmCPR123) and the gene for B. mori DNA replication licensing factor Mcm2-like (BmMCM2) were key genes among the common up-regulated DEGs, whereas the gene for B. mori heat shock protein 20.1 (Bmhsp20.1) was the central gene among the shared down-regulated DEGs between Lan5 vs Lan5-CPV and Ou17 vs Ou17-CPV. These findings established a comprehensive database of genes that are differentially expressed in response to BmCPV infection between silkworm strains that differed in resistance to BmCPV and implied that these DEGs might be involved in B. mori immune responses against BmCPV infection.

Transcriptome analysis of Bombyx mori larval midgut during persistent and pathogenic cytoplasmic polyhedrosis virus infection

Many insects can be persistently infected with viruses but do not show any obvious adverse effects with respect to physiology, development or reproduction. Here, Bombyx mori strain Daizo, persistently infected with cytoplasmic polyhedrosis virus (BmCPV), was used to study the host's transcriptional response after pathogenic infection with the same virus in midgut tissue of larvae persistently and pathogenically infected as 2nd and 4th instars. Next generation sequencing revealed that from 13,769 expressed genes, 167 were upregulated and 141 downregulated in both larval instars following pathogenic infection. Several genes that could possibly be involved in B. mori immune response against BmCPV or that may be induced by the virus in order to increase infectivity were identified, whereas classification of differentially expressed transcripts (confirmed by qRT-PCR) resulted in gene categories related to physical barriers, immune responses, proteolytic/metabolic enzymes, heat-shock proteins, hormonal signaling and uncharacterized proteins. Comparison of our data with the available literature (pathogenic infection of persistently vs. non-persistently infected larvae) unveiled various similarities of response in both cases, which suggests that pre-existing persistent infection does not affect in a major way the transcriptome response against pathogenic infection. To investigate the possible host's RNAi response against BmCPV challenge, the differential expression of RNAi-related genes and the accumulation of viral small RNAs (vsRNAs) were studied. During pathogenic infection, siRNA-like traces like the 2-fold up-regulation of the core RNAi genes Ago-2 and Dcr-2 as well as a peak of 20 nt small RNAs were observed. Interestingly, vsRNAs of the same size were detected at lower rates in persistently infected larvae. Collectively, our data provide an initial assessment of the relative significance of persistent infection of silkworm larvae on the host response following pathogenic infection with CPV, while they also highlight the relative importance of RNAi as an antiviral mechanism.

Digital gene expression analysis of reproductive toxicity of benzo[a]pyrene in male scallop chlamys farreri

Benzo[a]pyrene (BaP) is a representative polycyclic aromatic hydrocarbon (PAH) and is studied widely for its strong toxicity and wide distribution. Although BaP pollution in marine environment is increasing, molecular mechanisms underlying reproductive toxicity of BaP in marine mollusks have been seldom systematically studied, especially in males. In this study, genes that regulated reproductive responses of Chlamys farreri under BaP stress were analyzed through digital gene expression (DGE) sequencing with testis tissues. A total of 12,485,055 and 14,454,127 clean reads were generated from control and BaP exposure DGE libraries, respectively. After comparing two libraries, 1051 differentially expressed genes were detected, with 223 up-regulated and 828 down-regulated genes. Gene ontology (GO) annotation and kyoto encyclopedia of genes and genomes (KEGG) pathway analyses were performed on all genes to understand their biological functions and processes. The results showed that numerous enriched, differentially expressed genes related to aromatic compound catabolic processes, spermatid development, microtubule-based movement, energy production and immune response. Quantitative real-time PCR was performed to verify the expressed genes of DGE. The study generated data to show the overall reproductive transcription responses of male C. farreri under BaP stress, and it also can serve as the reference for future study of organic pollutions in aquatic mollusks.