Project description:Despite the essentiality for faithful chromosome segregation, centromere architectures are diverse among eukaryotes and embody two main configurations: mono- and holocentromeres, referring respectively to localized or unrestricted distribution of centromeric activity. Of the two, some holocentromeres offer the curious condition of having arisen independently in multiple insects, most of which have lost the otherwise essential centromere-specifying factor CenH3 (first described as CENP-A in humans). The loss of CenH3 raises intuitive questions about how holocentromeres are organized and regulated in CenH3-lacking insects. Here, we report the first chromatin-level description of CenH3-deficient holocentromeres by leveraging recently-identified centromere components and genomics approaches to map and characterize the holocentromeres of the silk moth Bombyx mori, a representative lepidopteran insect lacking CenH3. This uncovered a robust correlation between the distribution of centromere sites and regions of low chromatin activity along B. mori chromosomes. Transcriptional perturbation experiments recapitulated the exclusion of B. mori centromeres from active chromatin. Based on reciprocal centromere occupancy patterns observed along differentially-expressed orthologous genes of Lepidoptera, we further found that holocentromere formation in a manner that is recessive to chromatin dynamics is evolutionarily conserved. Our results help us discuss the plasticity of centromeres in the context of a role for the chromosome-wide chromatin landscape in conferring centromere identity rather than the presence of CenH3. Given the co-occurrence of CenH3 loss and holocentricity in insects, we further propose that the evolutionary establishment of holocentromeres in insects was facilitated through the loss of a CenH3-specified centromere.
Project description:In insects, male accessory gland proteins (ACPs) are important reproductive proteins secreted by male accessory glands (MAGs) of the internal male reproductive system. During mating, ACPs were transferred along with sperms inside female bodies and have a significant impact on the physiology of female reproduction. Under sexual selection pressures, the ACPs exhibit remarkably rapid and divergent evolution and varies from species to species. The diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), is a major insect pest of cruciferous vegetables worldwide. The reproductive physiology on post-mating state of this species is still largely unknown, which is important for management of this pest. In this study, the ACPs transferred into females during mating were identified by using a tandem mass tags quantitative proteomic analysis. The MAGs were compared before and after mating immediately. In total, we identified 123 putative secreted ACPs, including most important physiological: regulators of proteolysis, transporters and protein export machinery, signal transduction and immunity. Comparing P. xylostella with other four insect ACPs, trypsins were the only ACPs detected in all insect species. This was the first time to identify and analyze ACPs in P. xylostella. Our results have provided an important list of putative secreted ACPs, and have set the stage for further explore functions of these putative proteins in P. xylostella reproduction.
Project description:In insects, male accessory gland proteins (ACPs) are important reproductive proteins secreted by male accessory glands (MAGs) of the internal male reproductive system. During mating, ACPs were transferred along with sperms inside female bodies and have a significant impact on the physiology of female reproduction. Under sexual selection pressures, the ACPs exhibit remarkably rapid and divergent evolution and varies from species to species. The diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), is a major insect pest of cruciferous vegetables worldwide. The reproductive physiology on post-mating state of this species is still largely unknown, which is important for management of this pest. In this study, the ACPs transferred into females during mating were identified by using a tandem mass tags quantitative proteomic analysis. The MAGs were compared before and after mating immediately. The proteomes of copulatory bursas (CB) in mated females shortly after mating were also analyzed by shotgun LC-MS/MS technique. In total, we identified 123 putative secreted ACPs, including most important physiological: regulators of proteolysis, transporters and protein export machinery, signal transduction and immunity. Comparing P. xylostella with other four insect ACPs, trypsins were the only ACPs detected in all insect species. We also identified some new insect ACPs, including protein with chitin binding Peritrophin-A domain, PMP-22/EMP/MP20/Claudin tight junction domain-containing protein, netrin-1, type II inositol 1,4,5-trisphosphate 5-phosphatase, two spaetzles, allatostatin-CC and cuticular protein. This was the first time to identify and analyze ACPs in P. xylostella. Our results have provided an important list of putative secreted ACPs, and have set the stage for further explore functions of these putative proteins in P. xylostella reproduction.
Project description:We characterized sperm from the seminal vesicles of male monarch butterflies (Danaus plexippus), in triplicate, identifying 548 high confidence proteins. As with all but the most basal lepidopteran species male monarch butterflies are sperm heteromorphic, producing fertilization competent and anucleate fertilization incompetent sperm morphs. Comparing this data to the sperm proteomes of the Carolina sphinx moth (Manduca sexta) and the fruit fly (Drosophila melanogaster) demonstrated high levels of functional coherence across proteomes, and conservation at the level of protein abundance and post-translational modification within Lepidoptera. Comparative genomic analyses revealed a significant reduction in orthology among Monarch sperm genes relative to the remainder of the genome in non-Lepidopteran insects. A substantial number of sperm proteins were found to be specific to Lepidoptera, lacking detectable homology outside this taxa. These findings are consistent with a burst of genetic novelty in the sperm proteome concurrent with the origin of heteromorphic spermatogenesis early in Lepidoptera evolution.
Project description:MicroRNAs (miRNAs) are involved in post-transcriptional regulation of gene expression. Since several miRNAs are known to affect the stability or translation of developmental regulatory genes, the origin of novel miRNAs may have contributed to the evolution of developmental processes and morphology. Lepidoptera (butterflies and moths) is a species-rich clade with a well-established phylogeny and abundant genomic resources, thereby representing an ideal system in which to study miRNA evolution. We sequenced small RNA libraries from developmental stages of two divergent lepidopterans, Cameraria ohridella (Horse chestnut Leafminer) and Pararge aegeria (Speckled Wood butterfly), discovering 90 and 81 conserved miRNAs respectively, and many species-specific miRNA sequences. Mapping miRNAs onto the lepidopteran phylogeny reveals rapid miRNA turnover and an episode of miRNA fixation early in lepidopteran evolution, implying that miRNA acquisition accompanied the early radiation of the Lepidoptera. One lepidopteran-specific miRNA gene, miR-2768, is located within an intron of the homeobox gene invected, involved in insect segmental and wing patterning. We identified cubitus interruptus (ci) as a likely direct target of miR-2768, and validated this suppression using a luciferase assay system. We propose a model by which miR-2768 modulates expression of ci in the segmentation pathway and in patterning of lepidopteran wing primordia. Examination of the small RNA complements pooled across life cycle stages in each of Cameraria ohridella and Pararge aegeria.
Project description:MicroRNAs (miRNAs) are involved in post-transcriptional regulation of gene expression. Since several miRNAs are known to affect the stability or translation of developmental regulatory genes, the origin of novel miRNAs may have contributed to the evolution of developmental processes and morphology. Lepidoptera (butterflies and moths) is a species-rich clade with a well-established phylogeny and abundant genomic resources, thereby representing an ideal system in which to study miRNA evolution. We sequenced small RNA libraries from developmental stages of two divergent lepidopterans, Cameraria ohridella (Horse chestnut Leafminer) and Pararge aegeria (Speckled Wood butterfly), discovering 90 and 81 conserved miRNAs respectively, and many species-specific miRNA sequences. Mapping miRNAs onto the lepidopteran phylogeny reveals rapid miRNA turnover and an episode of miRNA fixation early in lepidopteran evolution, implying that miRNA acquisition accompanied the early radiation of the Lepidoptera. One lepidopteran-specific miRNA gene, miR-2768, is located within an intron of the homeobox gene invected, involved in insect segmental and wing patterning. We identified cubitus interruptus (ci) as a likely direct target of miR-2768, and validated this suppression using a luciferase assay system. We propose a model by which miR-2768 modulates expression of ci in the segmentation pathway and in patterning of lepidopteran wing primordia.