Genome-Wide Identification and Characterization of WD40 Protein Genes in the Silkworm, Bombyx mori

WD40 proteins are scaffolding molecules in protein-protein interactions and play crucial roles in fundamental biological processes. Genome-wide characterization of WD40 proteins in animals has been conducted solely in humans. We retrieved 172 WD40 protein genes in silkworm (BmWD40s) and identified these genes in 7 other insects, 9 vertebrates and 5 nematodes. Comparative analysis revealed that the WD40 protein gene family underwent lineage-specific expansions during animal evolution, but did not undergo significant expansion during insect evolution. The BmWD40s were categorized into five clusters and 12 classes according to the phylogenetic classification and their domain architectures, respectively. Sequence analyses indicated that tandem and segmental duplication played minor roles in producing the current number of BmWD40s, and domain recombination events of multi-domain BmWD40s might have occurred mainly after gene duplication events. Gene Ontology (GO) analysis revealed that a higher proportion of BmWD40s was involved in processes, such as binding, transcription-regulation and cellular component biogenesis, compared to all silkworm genes annotated in GO. Microarray-based analysis demonstrated that many BmWD40s had tissue-specific expression and exhibited high and/or sex-related expression during metamorphosis. These findings contribute to a better understanding of the evolution of the animal WD40 protein family and assist the study of the functions of BmWD40s

Genome-Wide Identification and Characterization of Tyrosine Kinases in the Silkworm, Bombyx mori

The tyrosine kinases (TKs) are important parts of metazoan signaling pathways and play significant roles in cell growth, development, apoptosis and disease. Genome-wide characterization of TKs has been conducted in many metazoans, however, systematic information about this family in Lepidoptera is still lacking. We retrieved 33 TK-encoding genes in silkworm and classified them into 25 subfamilies by sequence analysis, without members in AXL, FRK, PDGFR, STYK1 and TIE subfamilies. Although domain sequences in each subfamily are conserved, TKs in vertebrates tend to be remarkably conserved and stable. Our results of phylogenetic analysis supported the previous conclusion for the second major expansion of TK family. Gene-Ontology (GO) analysis revealed that a higher proportion of BmTKs played roles in binding, catalysis, signal transduction, metabolism, biological regulation and response to stimulus, compared to all silkworm genes annotated in GO. Moreover, the expression profile analysis of BmTKs among multiple tissues and developmental stages demonstrated that many genes exhibited stage-specific and/or sex-related expression during embryogenesis, molting and metamorphosis, and that 8 BmTKs presented tissue-specific high expression. Our study provides systematic description of silkworm tyrosine kinases, and may also provide further insights into metazoan TKs and assist future studies addressing their functions

Flight Muscle and Wing Mechanical Properties are Involved in Flightlessness of the Domestic Silkmoth, Bombyx mori

Flight loss has occurred in many winged insect taxa. The flightless silkmoth Bombyx mori, is domesticated from the wild silkmoth, Bombyx mandarina, which can fly. In this paper, we studied morphological characteristics attributed to flightlessness in silkmoths. Three domestic flightless B. mori strains and one B. mandarina population were used to compare morphological components of the flight apparatus, including wing characteristics (shape, forewing area, loading, and stiffness), flight muscle (weight, ratio, and microscopic detail) and body mass. Compared with B. mandarina, B. mori strains have a larger body, greater wing loading, more flexible wings and a lower flight muscle ratio. The arrangement in microscopy of dorsal longitudinal flight muscles (DLFMs) of B. mori was irregular. Comparative analysis of the sexes suggests that degeneration of flight muscles and reduction of wing mechanical properties (stiffness) are associated with silkmoth flightlessness. The findings provide important clues for further research of the molecular mechanisms of B. mori flight loss

Candidate DEGs of interest in the melanic <i>sml</i> male.

<p>Candidate DEGs of interest in the melanic <i>sml</i> male.</p

Comparative Analysis of Transcriptomes among <i>Bombyx mori</i> Strains and Sexes Reveals the Genes Regulating Melanic Morph and the Related Phenotypes

<div><p>As a source of insect polymorphism, melanism plays an important role in ecological adaption and usually endows advantageous phenotypic-effects on insects. However, due to the mechanistic diversity, there are knowledge gaps in the molecular mechanisms underlying melanism and the related phenotypes. In silk moths, a recessive melanic mutant (<i>sex-controlled melanism</i>, <i>sml</i>) strain exhibits extended adult longevity. We took a transcriptome approach to perform a comparative analysis between this <i>sml</i> strain and a wild-type strain (Dazao). Our analysis resulted in the identification of 59 unique differentially expressed genes in the melanic mutant. Two key genes (<i>laccase2</i> and <i>yellow</i>) involved in melanin formation were significantly up-regulated in melanic individuals. The laccase2 B-type isoform (<i>BGIBMGA006746</i>) was found to likely participate in the silkworm cuticular melanism process at late pupal stage. <a href="http://www.baidu.com/link?url=0JjinuKYUPgI5zPnqL0npiSYgLY5P7VywRevo-4u8JP97Xiio4L7jY29tKFDo0RvcF2oRpWPHsfjtK9gmWUcZpjfHgKFh-Q9vXUTYkacO4K" target="_blank">Moreover</a>, we discovered 22 cuticular protein encoding genes with the possible function in melanin transport and/or maintenance. Based on our findings, we presume that the longer survival of the melanic <i>sml</i> male moths might be associated with the enhanced antioxidant defense systems and a reduction in the insulin/IGF-1 signaling pathway (IIS). These findings will facilitate the understanding of the molecular basis underlying melanism and the derived phenotypic-effects.</p></div

GO classification of DEGs.

<p>GO classification of DEGs obtained respectively from three pair of melanic-typical comparisons (<i>sml</i>_M vs <i>sml</i>_F, <i>sml</i>_M vs DZ_M and <i>sml</i>_M vs DZ_F). Significantly enriched GO terms are shown. Asterisks (*) indicate the nine common significantly enriched GO terms (corrected P-value less than 0.05) shared by the three pairwise melanic-typical comparisons. DZ represents Dazao; M represents male; F represents female.</p

Summary of transcriptome sequencing data.

<p>Summary of transcriptome sequencing data.</p