Isolation, cloning and deduced amino acid sequence of a novel glycoprotein from the haemolymph of the hawkmoth Manduca sexta

Afidopyropen suppresses silkworm growth and vitality by affecting carbohydrate metabolism and immune function

Afidopyropen has strong insecticidal toxicity to sucking pests by silencing the vanilloid-type transient receptor potential (TRPV) channels. However, the toxicity of afidopyropen to the Lepidoptera model insect silkworm remain unknown. In this study, the LC50 of afidopyropen to the silkworm at 72 h exposure was 256.82 mg/L. This indicates that afidopyropen is moderately toxic to the silkworm. Long-term exposure to concentrations of 100 mg/L, or less, of afidopyropen, significantly reduced silkworm growth, vitality, silk protein synthesis, and fecundity. A total of 220 differentially expressed genes (DEGs) were detected by transcriptome sequencing, among which 166 were downregulated and 54 were upregulated. Gene Ontology (GO) enrichment analysis showed that the DEGs were enriched in the immune system, immune response and carbohydrate metabolism. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis indicated that DEGs were primarily concentrated in carbohydrate metabolism and biosynthesis of neomycin, kanamycin and gentamicin. Genes related to carbohydrate metabolism and immune system pathways in silkworm were detected by quantitative real-time PCR. The results showed that the genes related to carbohydrate metabolism, silk protein synthesis, and immune response were significantly downregulated. These genes included BCL-6 corepressor-like protein 1 (BCORL1), hexokinase type 2 (HEXO2), phosphoserine aminotransferase 1 (PSAT1), relish (Rel), peptidoglycan recognition protein 2 (PGRP2) and 27 kda glycoprotein precursor (P27K). The data demonstrated the toxic effects of afidopyropen against the silkworm and its regulation of genes responsible for immune function and abscissa carbohydrate metabolism.

Hemocyte Clusters Defined by scRNA-Seq in Bombyx mori: In Silico Analysis of Predicted Marker Genes and Implications for Potential Functional Roles

Within the hemolymph, insect hemocytes constitute a heterogeneous population of macrophage-like cells that play important roles in innate immunity, homeostasis and development. Classification of hemocytes in different subtypes by size, morphology and biochemical or immunological markers has been difficult and only in Drosophila extensive genetic analysis allowed the construction of a coherent picture of hemocyte differentiation from pro-hemocytes to granulocytes, crystal cells and plasmatocytes. However, the advent of high-throughput single cell technologies, such as single cell RNA sequencing (scRNA-seq), is bound to have a high impact on the study of hemocytes subtypes and their phenotypes in other insects for which a sophisticated genetic toolbox is not available. Instead of averaging gene expression across all cells as occurs in bulk-RNA-seq, scRNA-seq allows high-throughput and specific visualization of the differentiation status of individual cells. With scRNA-seq, interesting cell types can be identified in heterogeneous populations and direct analysis of rare cell types is possible. Next to its ability to profile the transcriptomes of individual cells in tissue samples, scRNA-seq can be used to propose marker genes that are characteristic of different hemocyte subtypes and predict their functions. In this perspective, the identities of the different marker genes that were identified by scRNA-seq analysis to define 13 distinct cell clusters of hemocytes in larvae of the silkworm, Bombyx mori, are discussed in detail. The analysis confirms the broad division of hemocytes in granulocytes, plasmatocytes, oenocytoids and perhaps spherulocytes but also reveals considerable complexity at the molecular level and highly specialized functions. In addition, predicted hemocyte marker genes in Bombyx generally show only limited convergence with the genes that are considered characteristic for hemocyte subtypes in Drosophila.

Allergenic Characterization of 27-kDa Glycoprotein, a Novel Heat Stable Allergen, from the Pupa of Silkworm, Bombyx mori

Boiled silkworm pupa is a traditional food in Asia, and patients with silkworm pupa food allergy are common in these regions. Still now only one allergen from silkworm, arginine kinase, has been identified. The purpose of this study was to identify novel food allergens in silkworm pupa by analyzing a protein extract after heat treatment. Heat treated extracts were examined by proteomic analysis. A 27-kDa glycoprotein was identified, expressed in Escherichia coli, and purified. IgE reactivity of the recombinant protein was investigated by ELISA. High molecular weight proteins (above 100 kDa) elicited increased IgE binding after heat treatment compared to that before heat treatment. The molecular identities of these proteins, however, could not be determined. IgE reactivity toward a 27-kDa glycoprotein was also increased after heating the protein extract. The recombinant protein was recognized by IgE antibodies from allergic subjects (33.3%). Glycation or aggregation of protein by heating may create new IgE binding epitopes. Heat stable allergens are shown to be important in silkworm allergy. Sensitization to the 27-kDa glycoprotein from silkworm may contribute to elevation of IgE to silkworm.

Clawing through evolution: toxin diversification and convergence in the ancient lineage Chilopoda (centipedes)

Despite the staggering diversity of venomous animals, there seems to be remarkable convergence in regard to the types of proteins used as toxin scaffolds. However, our understanding of this fascinating area of evolution has been hampered by the narrow taxonomical range studied, with entire groups of venomous animals remaining almost completely unstudied. One such group is centipedes, class Chilopoda, which emerged about 440 Ma and may represent the oldest terrestrial venomous lineage next to scorpions. Here, we provide the first comprehensive insight into the chilopod "venome" and its evolution, which has revealed novel and convergent toxin recruitments as well as entirely new toxin families among both high- and low molecular weight venom components. The ancient evolutionary history of centipedes is also apparent from the differences between the Scolopendromorpha and Scutigeromorpha venoms, which diverged over 430 Ma, and appear to employ substantially different venom strategies. The presence of a wide range of novel proteins and peptides in centipede venoms highlights these animals as a rich source of novel bioactive molecules. Understanding the evolutionary processes behind these ancient venom systems will not only broaden our understanding of which traits make proteins and peptides amenable to neofunctionalization but it may also aid in directing bioprospecting efforts.

Identification of a putative invertebrate helical cytokine similar to the ciliary neurotrophic factor/leukemia inhibitory factor family by PSI-BLAST-based approach

Most of our knowledge of helical cytokine-like molecules in invertebrates relies on functional assays and similarities at the physicochemical level. It is hard to predict helical cytokines in invertebrates based on sequences from mammals and vertebrates, because of their long evolutionary divergence. In this article, we collected 12 kinds of fish cytokines and constructed their respective consensus sequences using hidden Markov models; then, the conserved domains region of each consensus sequence were further extracted by the SMART tool, and used as the query sequence for PSI-BLAST analysis in Drosophila melanogaster. After two filtering processes based on the properties of helical cytokines, we obtained one protein named CG14629, which shares 25% identities/46% positives to fish M17 cytokine in the half length of the N-terminus. Considering the homology between M17 and LIF/CNTF (leukemia inhibitory factor/ciliary neurotrophic factor), and the close relationship between Dome, the putative cytokine receptor in Drosophila cells, and LIFR/CNTFR (LIF receptor/CNTF receptor), the results suggest that CG14629 is a good candidate for the helical cytokine ortholog in D. melanogaster.

The hemolymph proteome of Anopheles gambiae

We used two-dimensional SDS-PAGE and microsequencing or peptide mass fingerprinting to identify major proteins in the hemolymph of Anopheles gambiae. We found approximately 280 protein spots in hemolymph and identified 28 spots, representing 26 individual proteins. Most of these proteins have known or predicted functions in immunity, iron transport, or lipid biology. Many of the proteins have been found in hemolymph in other insects but one protein is novel: a new member of the ML family (involved in lipid recognition). Three of the identified proteins increased in spot intensity or appeared de novo following bacterial injection: a phenoloxidase, and two chitinase-like proteins. A subset of proteins decreased following bacterial injections: these included the light and heavy chains of ferritin. Several proteins appeared in hemolymph following any wound or injection. Most of these are metabolic enzymes lacking signal peptides that are likely to be released as a result of damage to muscles and other tissues by injury. The map will provide a useful tool for examining changes in hemolymph proteins following blood feeding and infection by parasites.

Effects of two hemolymph proteins on humoral defense reactions in the wax moth, Galleria mellonella

Two hemolymph proteins were isolated from the wax moth, Galleria mellonella, larvae by a two-step procedure consisting of acid extraction and reversed phase (RP)-HPLC. One was an apolipophorin III (apoLp-III) previously characterized as a lipopolysaccharide (LPS) binding protein in the hemolymph of G. mellonella. The other was confirmed to be a new protein with a molecular mass of 23,768.69 Da, referred to as Gm protein-24. The full-length cDNA of Gm protein-24 was cloned from the fat body. The cDNA structure showed that it is a 219-residues protein derived from the precursor of 236 amino acids. The effects of apoLp-III and Gm protein-24 have been tested on the insect humoral immunity. ApoLp-III enhanced the activity of antibacterial peptide such as cecropin but Gm protein-24 had no effect on cecropin activity. On the other hand, Gm protein-24 and apoLp-III were both involved in the activation of prophenoloxidase (PPO) cascade, which has been regarded as a critical immune reaction in insect hemolymph. Of note, the Gm protein-24 was a significantly stronger activator of PPO cascade than apoLp-III.