A serine protease homologue Bombyx mori scarface induces a short and fat body shape in silkworm

Adaptation of Helicoverpa armigera to Soybean Peptidase Inhibitors Is Associated with the Transgenerational Upregulation of Serine Peptidases

Molecular phenotypes induced by environmental stimuli can be transmitted to offspring through epigenetic inheritance. Using transcriptome profiling, we show that the adaptation of Helicoverpa armigera larvae to soybean peptidase inhibitors (SPIs) is associated with large-scale gene expression changes including the upregulation of genes encoding serine peptidases in the digestive system. Furthermore, approximately 60% of the gene expression changes induced by SPIs persisted in the next generation of larvae fed on SPI-free diets including genes encoding regulatory, oxidoreductase, and protease functions. To investigate the role of epigenetic mechanisms in regulating SPI adaptation, the methylome of the digestive system of first-generation larvae (fed on a diet with and without SPIs) and of the progeny of larvae exposed to SPIs were characterized. A comparative analysis between RNA-seq and Methyl-seq data did not show a direct relationship between differentially methylated and differentially expressed genes, while trypsin and chymotrypsin genes were unmethylated in all treatments. Rather, DNA methylation potential epialleles were associated with transcriptional and translational controls; these may play a regulatory role in the adaptation of H. armigera to SPIs. Altogether, our findings provided insight into the mechanisms of insect adaptation to plant antiherbivore defense proteins and illustrated how large-scale transcriptional reprograming of insect genes can be transmitted across generations.

Serine pseudoproteases in physiology and disease

Serine proteases (SPs) constitute a very important family of enzymes, both physiologically and pathologically. The effects produced by these proteins have been explained by their proteolytic activity. However, the discovery of pharmacologically active SP molecules that show no enzymatic activity, as the so-called pseudo SPs or SP homologs (SPHs), has exposed a profoundly neglected possibility of nonenzymatic functions of these SP molecules. In this review, the most thoroughly described SPHs are presented. The main physiological domains in which SPHs operate appear to be in reproduction, embryonic development, immune response, host defense, and hemostasis. Hitherto unexplained actions of SPs should therefore be considered also as the result of the ligand-like attributes of SPs. The gain of a novel function by an SPH is a consequence of specific amino acid replacements that have resulted in a novel interaction interface or a 'catalytic trap'. Unraveling the SP/SPH interactome will provide a description of previously unknown physiological functions of SPs/SPHs, aiding the creation of innovative medical approaches.

Role of microsatellites in genetic analysis of Bombyx mori silkworm: a review

In the genome of Bombyx mori Linnaeus (1758), the microsatellites, or simple sequence repeats (SSR), feature among their particular characteristics a high adenine and thymine (A/T) content, low number of repeats, low frequency, and a grouping in "families" with similar flanking regions. Such characteristics may be the result of a complex interaction between factors that limit the size and dispersion of SSR loci—such as their high association with transposons—and mean that microsatellites within this taxon suitable as molecular markers are relatively rare. The determination of genetic profiles in populations and cell lines has not been affected owing to the high level of polymorphism, nor has the analysis of diversity, structure and genetic relationships. However, the scarcity of suitable microsatellites has restricted their application in genetic mapping, limiting them to preliminary identification of gene location of genes or quantitative trait loci (QTLs) related to thermotolerance, resistance to viruses, pigmentation patterns, body development and the weight of the cocoon, the cortex, the pupa and the filament. The review confirms that, as markers, microsatellites are versatile and perform well. They could thus be useful both to advance research in emerging countries with few resources seeking to promote sericulture in their territories, and to advance in the genetic and molecular knowledge of characteristics of productive and biological interest, given the latest technological developments in terms of the sequencing, identification, isolation and genotyping of SSR loci.

Comparative Analysis of the Integument Transcriptomes between Stick Mutant and Wild-Type Silkworms

In insects, the integument provides mechanical support for the whole body and protects them from infections, physical and chemical injuries, and dehydration. Diversity in integument properties is often related to body shape, behavior, and survival rate. The stick (sk) silkworm is a spontaneous mutant with a stick-like larval body that is firm to the touch and, thus, less flexible. Analysis of the mechanical properties of the cuticles at day 3 of the fifth instar (L5D3) of sk larvae revealed higher storage modulus and lower loss tangent. Transcriptome sequencing identified a total of 19,969 transcripts that were expressed between wild-type Dazao and the sk mutant at L5D2, of which 11,596 transcripts were novel and detected in the integument. Differential expression analyses identified 710 upregulated genes and 1009 downregulated genes in the sk mutant. Gene Ontology (GO) enrichment analysis indicated that four chitin-binding peritrophin A domain genes and a chitinase gene were upregulated, whereas another four chitin-binding peritrophin A domain genes, a trehalase, and nine antimicrobial peptides were downregulated. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis indicated that two functional pathways, namely, fructose and mannose metabolism and tyrosine metabolism, were significantly enriched with differentially-expressed transcripts. This study provides a foundation for understanding the molecular mechanisms underlying the development of the stiff exoskeleton in the sk mutant.