De novo transcriptome assembly and analysis of differential gene expression following peptidoglycan (PGN) challenge in Antheraea pernyi

Integrated biochemical and transcriptomic analysis reveals the effects of Burkholderia sp. SRB-1 on cadmium accumulating in Chrysopogon zizanioides L. under Cd stress

Application of plant growth-promoting rhizobacteria plays a vital role in enhancing phytoremediation efficiency. In this study, multiple approaches were employed to investigate the underlying mechanisms of Burkholderia sp. SRB-1 (SRB-1) on elevating Cd uptake and accumulation. Inoculation experiment indicated that SRB-1 could facilitate plant growth and Cd tolerance, as evidenced by the enhanced plant biomass and antioxidative enzymes activities. Cd content in plant shoots and roots increased about 36.56%-39.66% and 25.97%-130.47% assisted with SRB-1 when compared with control. Transcriptomics analysis revealed that SRB-1 upregulated expression of amiE, AAO1-2 and GA2-ox related to auxin and gibberellin biosynthesis in roots. Auxin and gibberellin, as hormone signals, regulated plant Cd tolerance and growth through activating hormone signal transduction pathways, which might also contribute to 67.94% increase of dry weight. The higher expression levels of ATP-binding cassette transporter subfamilies (ABCB, ABCC, ABCD and ABCG) in Chrysopogon zizanioides roots contributed to higher Cd uptake in Cd15 B (323.83 mg kg^-1) than Cd15 (136.28 mg kg^-1). Further, SRB-1 facilitated Cd migration from roots to shoots via upregulating the expression of Nramp, ZIP and HMA families. Our integrative analysis provided a molecular-scale perspective on Burkholderia sp. SRB-1 contributing to C. zizanioides performance.

Characterization and analysis of the transcriptome in Opisina arenosella from different developmental stages using single-molecule real-time transcript sequencing and RNA-seq

Opisina arenosella is one of the main pests harming coconut trees. To date, there have been few studies on the molecular genetics, biochemistry and physiology of O. arenosella at the transcriptional level, and there are no available reference genomes. Here, Illumina RNA sequencing combined with PacBio single-molecule real-time analysis was applied to study the transcriptome of this pest at different developmental stages, providing reference data for transcript expression analysis. Twelve samples of O. arenosella from different stages of development were sequenced using Illumina RNA sequencing, and the pooled RNA samples were sequenced with PacBio technology (Iso-Seq). A full-length transcriptome with 41,938 transcripts was captured, and the N50 and N90 lengths were 3543 bp and 1646 bp, respectively. A total of 36,925 transcripts were annotated in public databases, 6493 of which were long noncoding RNAs, while 2510 represented alternative splicing events. There were significant differences in the gene expression profiles at different developmental stages, with high levels of differential gene expression associated with growth, development, carbohydrate metabolism and immunity. This work provides resources and information for the study of the transcriptome and gene function of O. arenosella and provides a valuable foundation for understanding the changes in gene expression during development.

Sex pheromones and olfactory proteins in Antheraea moths: A. pernyi and A. polyphemus (Lepidoptera: Saturniidae)

Olfaction is essential for regulating the physiological and behavioral actions of insects with specific recognition of various odors. Antheraea moths (Lepidoptera: Saturniidae) possess relatively large bodies and antennae so that they are good subjects for exploring molecular aspects of insect olfaction. Current knowledge of the molecular aspects of Antheraea olfaction is focused on the Chinese tussah silkmoth A. pernyi Guérin-Méneville and another species A. polyphemus (Cramer) in their pheromones, odorant-binding proteins (OBPs), odorant receptors (ORs), odorant receptor coreceptors (ORCOs), sensory neuron membrane proteins (SNMPs), and odorant-degrading enzymes (ODEs). The first insect OBP, SNMP, and ODE were identified from A. polyphemus. This review summarizes the principal findings associated with the olfactory physiology and its molecular components in the two Antheraea species. Three types of olfactory neurons may have specific ORs for three respective sex-pheromone components, with the functional sensitivity and specificity mediated by three respective OBPs. SNMPs and ODEs are likely to play important roles in sex-pheromone detection, inactivation, and degradation. Identification and functional analysis of the olfactory molecules remain to be further performed in A. pernyi, A. polyphemus, and other Antheraea species.

Transcriptome analysis reveals gene expression changes of the fat body of silkworm (Bombyx mori L.) in response to selenium treatment

A comparative transcriptome analysis was conducted to investigate the gene expression changes in the fat body of silkworm after treatment with different concentrations (50 μM and 200 μM) of selenium (Se). 912 differential expression genes (DEGs) (371 up-regulated and 541 down-regulated) and 1420 DEGs (1078 up-regulated and 342 down-regulated) were identified in silkworm fat body treated with 50 μM and 200 μM of Se, respectively. In case of 50 μM group, DEGs were mainly enriched in the peroxisome pathway and fatty acid metabolism pathway, and later were associated with antioxidant defense and nutrition regulation. After 200 μM Se-treatment, DEGs were mainly located in the glycerolipid metabolism and arachidonic acid metabolism pathways, which further encoded detoxification related genes. Furthermore, 32 candidate DEGs from these pathways had been selected to confirm the RNA-seq data. Among these DEGs, 14 genes were up-regulated in the 50 μM Se-treated group (only three genes in the 200 μM Se-treated group) which were involved in lipid metabolism and antioxidant defense, and 13 up-regulated genes (only two genes were up-regulated in the 50 μM Se-treated group) were involved in detoxification of the 200 μM Se-treated group. These changes showed that lower concentration of Se could regulate the nutrition and promote antioxidation pathways; whereas, high levels of Se promoted the detoxification of silkworm. These findings can be helpful to understand the possible mechanisms of Se action and detoxification in silkworm and other insects.

Transcriptome analysis of differential expressed genes in hepatopancreas of Procambarus clarkii challenged with peptidoglycan

Procambarus clarkii is one of the most economically important species in Chinese aquaculture, and is widely cultured. Infection of P. clarkii populations with bacterial pathogens causes high mortality and great economic loss, therefore disease control is of significant economic importance. P. clarkii is a model system for studying immune responses in invertebrates, and its immune system consists solely of the innate response. In the present study, we examined gene expression related to immune function in P. clarkii in response to pathogen challenge. The transcriptome of hepatopancreas tissue from P. clarkii challenged with peptidoclycan (PGN) was analyzed and compared to control specimens. After assembly and annotation, 48,661 unigenes were identified with an average length of 671.54 bp. A total of 2533 differentially expressed genes (DEGs) were obtained, including 765 significantly up-regulated unigenes and 1757 significantly down-regulated unigenes. Gene ontology (GO) analysis demonstrated 19 biological process subcategories, 16 cellular component subcategories, and 17 molecular function subcategories that were enriched among these DEGs. Enrichment analysis using the Kyoto Encyclopedia of Genes and Genomes (KEGG) database revealed enrichment among immune responses pathways. Taken together, this study not only enriches the existing P. clarkii transcriptome database, but also elucidates immune responses of crayfish that are activated in response to PGN challenge.

Transcriptome Analysis Reveals Potential Antioxidant Defense Mechanisms in Antheraea pernyi in Response to Zinc Stress

The growth and development of the Chinese oak silkworm, Antheraea pernyi, are strongly influenced by environmental conditions, including heavy metal pollution. An excess of heavy metals causes cellular damage through the production of free radical reactive oxygen species. In this study, transcriptome analysis was performed to investigate global gene expression when A. pernyi was exposed to zinc infection. With RNA sequencing (RNA-Seq), a total of 25 795 510 and 38 158 855 clean reads were obtained from zinc-treated and control fat body libraries, respectively. We identified 2399 differential expression genes (DEGs) (1845 upregulated and 544 downregulated genes) in the zinc-treated library. In addition, Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis revealed that these DEGs were related to the peroxisome pathway that was associated with antioxidant defense. Our results suggest that fat bodies of A. pernyi constitute a strong antioxidant defense against heavy metal contamination.

Isolation and functional characterization of the pheromone biosynthesis activating neuropeptide receptor of Chinese oak silkworm, Antheraea pernyi

Insect pheromone biosynthesis activating neuropeptide (PBAN) controls the synthesis and actuating of sex pheromones of female adult. In the current examination, the full-length cDNA encoding the PBAN receptor was cloned from the pheromone gland (PG) of Antheraea pernyi (AntpePBANR). The AntpePBANR displayed the characteristic seven transmembrane areas of the G protein-coupled receptor (GPCR) and was closely related to the PBANR from Bombyx mori and Manduca sexta in the phylogenetic tree. The AntpePBANR expressed in mammalian cell lines were enacted by AntpePBAN in a concentration-dependent manner. AntpePBANR activation resulted in the calcium mobilization but did not activate the cAMP elevation pathway. Cells expressing AntpePBANR were profoundly responsive to Antpe-γ-SGNP (suboesophageal ganglion neuropeptides) and Antpe-DH (diapause hormone), different individuals from FXPRLamide (X = T, S or V) family in A. pernyi. Deletion of residues in the C-terminal hexapeptide (FSPRLamide) proved that P, R and L played the key parts in initiating the AntpePBANR, the amination to the last C terminal residues which can also likewise impact the activation of AntpePBAN receptor altogether. The mRNA of the AntpePBANR gene demonstrated the most noteworthy transcript levels in pheromone gland followed by fat body.