A corset function of exoskeletal ECM promotes body elongation in Drosophila

Body elongation is a general feature of development. Postembryonically, the body needs to be framed and protected by extracellular materials, such as the skeleton, the skin and the shell, which have greater strength than cells. Thus, body elongation after embryogenesis must be reconciled with those rigid extracellular materials. Here we show that the exoskeleton (cuticle) coating the Drosophila larval body has a mechanical property to expand less efficiently along the body circumference than along the anteroposterior axis. This “corset” property of the cuticle directs a change in body shape during body growth from a relatively round shape to an elongated one. Furthermore, the corset property depends on the functions of Cuticular protein 11 A and Tubby, protein components of a sub-surface layer of the larval cuticle. Thus, constructing a stretchable cuticle and supplying it with components that confer circumferential stiffness is the fly’s strategy for executing postembryonic body elongation.

Computational analyses decipher the primordial folding coding the 3D structure of the beetle horn

The beetle horn primordium is a complex and compactly folded epithelial sheet located beneath the larval cuticle. Only by unfolding the primordium can the complete 3D shape of the horn appear, suggesting that the morphology of beetle horns is encoded in the primordial folding pattern. To decipher the folding pattern, we developed a method to manipulate the primordial local folding on a computer and clarified the contribution of the folding of each primordium region to transformation. We found that the three major morphological changes (branching of distal tips, proximodistal elongation, and angular change) were caused by the folding of different regions, and that the folding mechanism also differs according to the region. The computational methods we used are applicable to the morphological study of other exoskeletal animals.

Preparation and biological activity evaluation of some benzoylthiourea and benzoylurea compounds

Due to the complicated problems coming from excessive applications of insecticides, searching for safe substitutes to these insecticides has become a necessity. Thus, the insect growth regulators are candidates to be used in such concern. Comparative studies of the effects of three compounds, 2-benzoyl-N-phenylhydrazine-1-carbothioamide (1), 2-(cyanoacetyl)-N-phenylhydrazine-1-carboxamide (2) and N-(2-(2-cyanoacetyl)hydrazinecarbonothioyl)furan-2-carboxamide (3) (an insect growth regulator inhibiting chitin synthesis), were conducted on Spodoptera littoralis (Boisduval, 1833). The compounds, orally administered, caused larval mortality proportional to the concentrations in the food source. larvae were unable to complete the molting process and died in the old larval cuticle. Larvae contaminated by sublethal doses completed their development to adulthood. N-(2-(2-cyanoacetyl)hydrazinecarbonothioyl)furan-2-carboxamide (3) is more active than the other compounds have LC50 17.082 ppm for 2nd instar larvae and 60.832 ppm for 4th instar larvae.

Computational analyses decipher the primordial folding coding the 3D structure of the beetle horn

The beetle horn primordium is a complex and compactly folded epithelial sheet located beneath the larval cuticle. Only by unfolding the primordium the complete 3D shape of the horn appears, suggesting that the morphology of beetle horns is coded in the primordial folding pattern. To decipher the folding pattern, we have developed a method to manipulate the primordial local folding, reproduced it on a computer, and clarified the contribution of the folding of each primordium region to transformation. We found that the three major morphological changes (branching of distal tips, proximodistal elongation, and angular change) were caused by the folding of different regions, and that the folding mechanism was also different depending on the region. The computational methods we used are applicable to the morphological study of other exoskeletal animals.

mRNA and Small RNA-seq Reveal Insights into Immune Regulation in Apis cerana after Chinese Sacbrood Virus Infection

Chinese sacbrood virus (CSBV) is a serious threat to eastern honeybees (Apis cerana), especially larvae. However, the pathological mechanism of this deadly disease is remains unclear. Here, we employed an mRNA-seq and sRNA-seq approach in healthy and CSBV-infected 3rd Apis cerana larval. Gene ontology (GO) and KEGG analysis of 203 differentially expressed genes showed that CSBV infection affected host development by up-regulating the expression of larval cuticle proteins, such as larval cuticle proteins A1A and A3A, resulting in elevated susceptibility to CSBV. In addition, viral infection not only affected the expression of serine protease related to the melanization pathway and but also altered fatty acid metabolism and biosynthesis, thus progressed to disturb host immune response. Interestingly, GO annotation and KEGG analysis on target genes of CSBV-specific siRNA (vsiRNAs) showed that serine/threonine kinase activity and serine-type endopeptidas as well as fatty acid biosynthesis were significantly enriched (P < 0.05). Among these vsiRNAs, vsiRNA-1441 with relatively high expression targeted extracellular serine/threonine protein kinase. This study provides new evidence that CSBV attacks a distinct immune response pathway and mediates the expression of cuticle protein to gain the more chance of proliferation.

Evolutionary origin and functioning of pregenital abdominal outgrowths in a viviparous insect, Arixenia esau

Although pregenital abdominal outgrowths occur only rarely in pterygote insects, they are interesting from the evolutionary viewpoint because of their potential homology to wings. Our previous studies of early development of an epizoic dermapteran, Arixenia esau revealed that abdominal segments of the advanced embryos and larvae, growing inside a mother’s uterus, are equipped with paired serial outgrowths. Here, we focus on the origin and functioning of these outgrowths. We demonstrate that they bud from the lateral parts of the abdominal nota, persist till the end of intrauterine development, and remain in contact with the uterus wall. We also show that the bundles of muscle fibers associated with the abdominal outgrowths may facilitate flow of the haemolymph from the outgrowths’ lumen to the larval body cavity. Following completion of the intrauterine development, abdominal outgrowths are shed together with the larval cuticle during the first molt after the larva birth. Using immunohistochemical and biochemical approaches, we demonstrate that the Arixenia abdominal outgrowths represent an evolutionary novelty, presumably related to intrauterine development, and suggest that they are not related to serial wing homologs.

Pyrethroid exposure altersAnopheles albimanusmicrobiota and resistant mosquitoes harbor more insecticide-metabolizing bacteria

A deeper understanding of the mechanisms underlying insecticide resistance is needed to mitigate its threat to malaria vector control. Building upon our earlier identified associations between mosquito microbiota and insecticide resistance, we demonstrate for the first time, type-specific effects of pyrethroid exposure on internal and cuticle surface bacteria in adult progeny of field-collectedAnopheles albimanus. In contrast, larval cuticle surface—but not internal—bacteria were affected by pyrethroid exposure. Being over five-folds more abundant in pyrethroid resistant adults, as compared to susceptible or non-insecticide-exposed mosquitoes,Klebsiella(alphacypermethrin),PantoeaandAsaia(permethrin) were identified as potential markers of pyrethroid resistance inAn. albimanus. We also show for the first time thatAn. albimanuslarvae and adult cuticles harbor more diverse bacterial communities than their internal microbial niches. Our findings indicate insecticide selection pressures on mosquito microbiota, and support the hypothesis of an undescribed microbe-mediated mechanism of insecticide metabolism in mosquitoes.