摘要: Salivary gland-specific transcriptomes of nine heteropteran insects with distinct feeding strategies (predaceous, hematophagous, and phytophagous) were analyzed and annotated to compare and identify the venom components as well as their expression profiles. The transcriptional abundance of venom genes was verified via quantitative real-time PCR. Hierarchical clustering of 30 representative differentially expressed venom genes from the nine heteropteran species revealed unique groups of salivary gland-specific genes depending on their feeding strategy. The commonly transcribed genes included a paralytic neurotoxin (arginine kinase), digestive enzymes (cathepsin and serine protease), an anti-inflammatory protein (cystatin), hexamerin, and an odorant binding protein. Both predaceous and hematophagous (bed bug) heteropteran species showed relatively higher transcription levels of genes encoding proteins involved in proteolysis and cytolysis, whereas phytophagous heteropterans exhibited little or no expression of these genes, but had a high expression of vitellogenin, a multifunctional allergen. Saliva proteomes from four representative species were also analyzed. All venom proteins identified via saliva proteome analysis were annotated using salivary gland transcriptome data. The proteomic expression profiles of venom proteins were in good agreement with the salivary gland-specific transcriptomic profiles. Our results indicate that profiling of the salivary gland transcriptome provides important information on the composition and evolutionary features of venoms depending on their feeding strategy.

摘要: The sigma glutathione S-transferases (GSTSs) are a class of cytosolic glutathione S transferases (GSTs) that play important roles in antioxidant defense in insects, but the mechanisms by which GSTSs contribute to antioxidant activity remain unclear. Here, we isolated a GSTS (GSTS6) from Tribolium castaneum and explored its function. Homology and phylogenetic analysis revealed that TcGSTS6 shared high identity with other evolutionarily conserved GSTSs. The recombinant TcGSTS6 protein had strong activity toward cumene hydroperoxide and 4-hydroxynonenal but low activity toward the universal substrate 1-chloro-2,4-dinitrobenzene. Exposure to various types of oxidative stress, including heat, cold, UV and pathogenic microbes, significantly induced TcGSTs6 expression, which indicates that it is involved in antioxidant defense. Knockdown TcGSTs6 by using RNA interference (RNAi) caused reduced antioxidant capacity, which was accomplished by cooperating with other antioxidant genes. Moreover, treatment with various insecticides such as phoxim, lambda-cyhalothrin, dichlorvos and carbofuran revealed that TcGSTS6 plays an important role in insecticide detoxification. The RNAi results showed that TcGSTS6 is essential for embryogenesis in T. castaneum. Our study elucidates the mechanism by which a GSTS contributes to antioxidant activity and enhances our understanding of the functional diversity of GSTSs in insects.

摘要: The halictid genus Lasioglossum, as one of the most species-rich bee groups with persistently contentious subgeneric boundaries, is one of the most challenging bee groups from a systematic standpoint. An enduring question is the relationship of Lasioglossum and Homalictus, whether all halictine bees with weakened distal wing venation comprise one or multiple genera. Here, we analyzed the phylogenetic relationships among the subgroups within Lasioglossum s.l. based on thousands of single-copy orthologs and ultraconserved elements, which were extracted from 23 newly sequenced low-coverage whole genomes alongside a published genome (22 ingroups plus 2 outgroups). Both marker sets provided consistent results across maximum likelihood and coalescent-based species tree approaches. The phylogenetic and topology test results show that the Lasioglossum and Hemihalictus series are reciprocally monophyletic and Homalictus and Rostrohalictus are valid subgenera of Lasioglossum. Consequently, we lower Homalictus to subgenus status within Lasioglossum again, and we also raise Rostrohalictus to subgenus status from its prior synonymy with subgenus Hemihalictus. Lasioglossum przewalskyi is also transferred to the subgenus Hemihalictus. Ultimately, we redefine Lasioglossum to include all halictine bees with weakened distal wing venation.

摘要: Eye position varies significantly among taxonomic levels, and this variation is often shaped by ecological and behavioral factors. Eye position is often positively associated with interorbital distance where species with broad visual fields possess a large distance between the left and right eye. Selective pressures underlying the evolution of the eye position are especially studied in birds and mammals. However, selective pressures underlying the evolution of anuran eye position which can be indicated by interorbital distance keep unknown. Here, we investigated the effects of ecological (e.g. habitat type, light availability) and behavioral factors (e.g. activity pattern, foraging mobility, and defensive strategy) on variations in interorbital distance among 260 anuran species in China. Our results showed that variations of the interorbital distance can be significantly predicted by the activity pattern. Nocturnal species had larger interorbital distance than both nocturnal and diurnal species. We also found that foraging mobility and defensive strategy markedly affected variation of interorbital distance. Species having slower foraging mobility and possessing poison glands had larger interorbital distance than species having faster foraging mobility and possessing non-position glands. Light availability tended to be associated with variation of interorbital distance, indicating that species living in weak light tended to possess larger interorbital distance. However, variations of the interorbital space were not associated with habitat type in anurans. Our findings suggest that anuran behaviors play key roles in shaping visual fields and eye position, thus affecting the evolution of interorbital distance.

摘要: The Lusitanian (Microtus lusitanicus) and the Mediterranean (Microtus duodecimcostatus) pine voles are recently diverged sister species endemic of the Iberian Peninsula that can be identified with ecological and morphological characters, but in areas where the 2 species co-occur, species designation may be difficult. Genetic discrimination between M. lusitanicus and M. duodecimcostatus has not been achieved yet possibly because of their estimated recent split and an evolutionary history that includes inter-species gene flow. Following our previous observations on exons 5-7 of the p53 gene, here we analyze the potential use of the p53 genomic region as a discrimination marker of these species by extending our analyses to several kb upstream and downstream of the p53 gene and characterizing the degree of genetic differentiation in 7 markers within this region. Additionally, we fully sequenced the P53 protein of both species. We observed: (i) generally high differentiation in this region; (ii) M. duodecimcostatus showed in general higher values of nucleotide and haplotype diversities; (iii) the concatenated phylogenetic tree separates the 2 species; (iv) the 2 P53 proteins only differ in 1 amino acid; (v) 4 of the markers, 2 in p53, one in Atp1b2, and another in Wrap53, contain species-specific genetic variation thus allowing a reliable discrimination between specimens from both species, irrespective of sampling location or introgression status. We provide additional data on the putative role of p53 in the evolution of these species and present researchers with a fast and cost-effective resource for M. lusitanicus and M. duodecimcostatus identification.