LepChorionDB, a database of Lepidopteran chorion proteins and a set of tools useful for the identification of chorion proteins in Lepidopteran proteomes

Exochorion in the tribe Nymphalini (Lepidoptera: Nymphalidae): the genus Hypanartia Hbner, [1821] and comparison with related genera

We describe and compare the exochorion of six species of Hypanartia (H. paullus, H. bella, H. lethe, H. godmanii, H. dione disjuncta, and H. trimaculata autumna) using specimens collected in the field and deposited in entomological collections. We used a standard staining technique and scanning electron microscopy to visualize and describe the main exochorionic characters, especially the ridges and the differentiation in the micropylar, perimicropylar, and transition zones in the apical region. We included plates with photographs, drawings, and schemes for clearer visualization of these structures, which are tabulated for comparison. For our characterization, we considered the ridges in colonnade as the main exochorionic feature in the Nymphalini. Thus, we made brief comparisons of these features among several species of the tribe, particularly with the genus Antanartia. The exochorionic characters agree with the separation of groups (paullus group and dione group). By examining the characteristics of H. paullus, the basal species of the paullus group, we found that ridges with conspicuous columns (e.g., in one section only) appears to be the plesiomorphic state, while those with elongated shafts and walls only in the intercolumn represent the apomorphic state.

Hexapeptide Tandem Repeats Dictate the Formation of Silkmoth Chorion, a Natural Protective Amyloid

Silkmoth chorion is a fibrous structure composed mainly of two major protein classes, families A and B. Both families of silkmoth chorion proteins present a highly conserved, in sequence and in length, central domain, consisting of Gly-rich tandem hexapeptide repetitive segments, flanked by two more variable N-terminal and C-terminal arms. Primary studies identified silkmoth chorion as a functional protective amyloid by unveiling the amyloidogenic properties of the central domain of both protein families. In this work, we attempt to detect the principal source of amyloidogenicity of the central domain by focusing on the role of the tandem hexapeptide sequence repeats. Concurrently, we discuss a possible mechanism for the self-assembly of class A protofilaments, suggesting that the aggregation-prone hexapeptide building blocks may fold into a triangle-shaped β-helical structure.

Key enzymes and proteins of crop insects as candidate for RNAi based gene silencing

RNA interference (RNAi) is a mechanism of homology dependent gene silencing present in plants and animals. It operates through 21-24 nucleotides small RNAs which are processed through a set of core enzymatic machinery that involves Dicer and Argonaute proteins. In recent past, the technology has been well appreciated toward the control of plant pathogens and insects through suppression of key genes/proteins of infecting organisms. The genes encoding key enzymes/proteins with the great potential for developing an effective insect control by RNAi approach are actylcholinesterase, cytochrome P450 enzymes, amino peptidase N, allatostatin, allatotropin, tryptophan oxygenase, arginine kinase, vacuolar ATPase, chitin synthase, glutathione-S-transferase, catalase, trehalose phosphate synthase, vitellogenin, hydroxy-3-methylglutaryl coenzyme A reductase, and hormone receptor genes. Through various studies, it is demonstrated that RNAi is a reliable molecular tool which offers great promises in meeting the challenges imposed by crop insects with careful selection of key enzymes/proteins. Utilization of RNAi tool to target some of these key proteins of crop insects through various approaches is described here. The major challenges of RNAi based insect control such as identifying potential targets, delivery methods of silencing trigger, off target effects, and complexity of insect biology are very well illustrated. Further, required efforts to address these challenges are also discussed.