The Argonaute protein family is a highly conserved group of proteins, which have been implicated in RNA silencing in both plants and animals. Here, four members of the Argonaute family were systemically identified bas...The Argonaute protein family is a highly conserved group of proteins, which have been implicated in RNA silencing in both plants and animals. Here, four members of the Argonaute family were systemically identified based on the genome sequence of Bombyx mori. Based on their sequence similarity, BmAgol and BmAgo2 belong to the Ago subfamily, while BmAgo3 and BmPiwi are in the Piwi subfamily. Phylogenetic analysis reveals that silkworm Argonaute family members are conserved in insects. Conserved amino acid residues involved in recognition of the 5＇ end of the small RNA guide strand and of the conserved （aspartate, aspartate and histidine [DDH]） motif present in their PIWI domains suggest that these four Argonaute family members may have conserved slicer activities. The results of microarray expression analysis show that there is a low expression level for B. mori Argonaute family members in different tissues and different developmental stages, except for BmPiwi. All four B. mori Argonaute family members are upregulated upon infection with B. mori nucleopolyhedrovirus. The complete coding sequence of BmPiwi, the homolog of Drosophila piwi, was cloned and its expression occurred mainly in the area where spermatogonia and spermatocytes appear. Our results provide an overview of the B. mori Argonaute family members and suggest that they may have multiple roles. In addition, this is also the first report, to our knowledge, of the response of RNA silencing machinery to DNA virus infection in insects.展开更多
Tarantula venoms provide a model system for studying toxin selectivity, structure-activity relationships and molecular evolution ofpeptide toxins. Previous studies have identified a large number of peptide toxins in t...Tarantula venoms provide a model system for studying toxin selectivity, structure-activity relationships and molecular evolution ofpeptide toxins. Previous studies have identified a large number of peptide toxins in the venom of the Chinese bird spider Haplopelma hainanum, generally regarded as a highly venomous spider. However, the lack of available RNA-seq transcriptomic and genomic data is an obstacle to understanding its venom at the molecular level. In this study, we investigated the venom gland transcriptome of/-/, hainanum by RNA-seq, in the absence of an available genomic sequence. We identi- fied 201 potential toxins among 57 18 l de novo assembled transcripts, including knottins, Kunitz-type toxins, enzymes and other proteins. We systematically identified most of the knottins and Kunitz-type toxins, some of which showed strongly biased expression in the venom gland, including members of the huwentoxin-1, huwentoxin-2 and magi-1 families. We also discovered several novel potential toxins. These data demonstrate the high molec- ular and structural diversity in the venom toxins ofH. hainanum. This study offers a useful strategy for exploring the complex components of spider venoms.展开更多
Cecropin A1 （CeeA1） promoter from Bombyx mori was cloned and character- ized to provide insight into the transcriptional control of this antimicrobial peptide gene upon immune challenges. Reporter gene assays demons...Cecropin A1 （CeeA1） promoter from Bombyx mori was cloned and character- ized to provide insight into the transcriptional control of this antimicrobial peptide gene upon immune challenges. Reporter gene assays demonstrated that both Escherichia coli and lipopolysaccharide could induce expression in BmE cells but B. bombyseptieus or peptidoglycan failed, and the induction pattern of the reporter gene was coincident with the endogenous CecAl. Analysis of deletion and mutation constructs revealed that the regulatory region was the κB motif located between -176 and -166, and no other pre- dicted elements on CecAl promoter affected its inducibility. Insertion of additional κB motifs increased the activity of CecAl promoter. Furthermore, binding of Relish to lob motif was confirmed by electrophoretic mobility shift assay. These findings indicate the regulatory mechanism of CecAl expression in IMD pathway and suggest an approach of engineering antimicrobial peptide promoter with enhanced activities that may lead to broad applications.展开更多
文摘The Argonaute protein family is a highly conserved group of proteins, which have been implicated in RNA silencing in both plants and animals. Here, four members of the Argonaute family were systemically identified based on the genome sequence of Bombyx mori. Based on their sequence similarity, BmAgol and BmAgo2 belong to the Ago subfamily, while BmAgo3 and BmPiwi are in the Piwi subfamily. Phylogenetic analysis reveals that silkworm Argonaute family members are conserved in insects. Conserved amino acid residues involved in recognition of the 5＇ end of the small RNA guide strand and of the conserved （aspartate, aspartate and histidine [DDH]） motif present in their PIWI domains suggest that these four Argonaute family members may have conserved slicer activities. The results of microarray expression analysis show that there is a low expression level for B. mori Argonaute family members in different tissues and different developmental stages, except for BmPiwi. All four B. mori Argonaute family members are upregulated upon infection with B. mori nucleopolyhedrovirus. The complete coding sequence of BmPiwi, the homolog of Drosophila piwi, was cloned and its expression occurred mainly in the area where spermatogonia and spermatocytes appear. Our results provide an overview of the B. mori Argonaute family members and suggest that they may have multiple roles. In addition, this is also the first report, to our knowledge, of the response of RNA silencing machinery to DNA virus infection in insects.
文摘Tarantula venoms provide a model system for studying toxin selectivity, structure-activity relationships and molecular evolution ofpeptide toxins. Previous studies have identified a large number of peptide toxins in the venom of the Chinese bird spider Haplopelma hainanum, generally regarded as a highly venomous spider. However, the lack of available RNA-seq transcriptomic and genomic data is an obstacle to understanding its venom at the molecular level. In this study, we investigated the venom gland transcriptome of/-/, hainanum by RNA-seq, in the absence of an available genomic sequence. We identi- fied 201 potential toxins among 57 18 l de novo assembled transcripts, including knottins, Kunitz-type toxins, enzymes and other proteins. We systematically identified most of the knottins and Kunitz-type toxins, some of which showed strongly biased expression in the venom gland, including members of the huwentoxin-1, huwentoxin-2 and magi-1 families. We also discovered several novel potential toxins. These data demonstrate the high molec- ular and structural diversity in the venom toxins ofH. hainanum. This study offers a useful strategy for exploring the complex components of spider venoms.
基金This work was supported by grants from the National Basic Research Program of China （No. 2012CB 114600） and the National Natural Science Foundation of China （No. 31201854）.
文摘Cecropin A1 （CeeA1） promoter from Bombyx mori was cloned and character- ized to provide insight into the transcriptional control of this antimicrobial peptide gene upon immune challenges. Reporter gene assays demonstrated that both Escherichia coli and lipopolysaccharide could induce expression in BmE cells but B. bombyseptieus or peptidoglycan failed, and the induction pattern of the reporter gene was coincident with the endogenous CecAl. Analysis of deletion and mutation constructs revealed that the regulatory region was the κB motif located between -176 and -166, and no other pre- dicted elements on CecAl promoter affected its inducibility. Insertion of additional κB motifs increased the activity of CecAl promoter. Furthermore, binding of Relish to lob motif was confirmed by electrophoretic mobility shift assay. These findings indicate the regulatory mechanism of CecAl expression in IMD pathway and suggest an approach of engineering antimicrobial peptide promoter with enhanced activities that may lead to broad applications.
