Molecular cloning and characterization of hatching enzyme-like geneII (BmHELII) in the silkworm, Bombyx mori

Sast1-mediated manifold effects inhibit Plutella xylostella fertility

BACKGROUND

Plutella xylostella (Linnaeus) is a destructive pest of cruciferous crops due to its strong reproductive capacity and extensive resistance to pesticides. Seminal fluid proteins (SFPs) are the main effective factors that determine the reproductive physiology and behaviour of both sexes. Although an increasing number of SFPs have been identified, the effects of astacins in SFPs on agricultural pests have not yet been reported. Here, we elucidated the mechanisms by which Sast1 (seminal astacin 1) regulates the fertility of Plutella xylostella (L.).

RESULTS

PxSast1 was specifically expressed in the testis and accesssory gland. CRISPR/Cas9-induced PxSast1 knockout successfully constructed two homozygous mutant strains. Sast1 impaired the fertility of P. xylostella by separately regulating the reproductive capacity of males and females. Loss of PxSast1, on the one hand, significantly decreased the ability of males to mate and fertilize, mainly manifested as shortened mating duration, reduced mating competitiveness and decreased eupyrene sperm production; on the other hand, it significantly inhibited the expression of chorion genes in females, resulting in oogenesis deficits. Simultaneously, for mated females, the differentially expressed genes in signalling pathways related to oogenesis and chorion formation were significantly enriched after PxSast1 knockout.

CONCLUSION

These analyses of the functions of PxSast1 as the regulator of spermatogenesis and oogenesis establish its importance in the fertility process of P. xylostella, as well as its potential as a promising target for genetic regulation-based pest control. © 2024 Society of Chemical Industry.

The light cycle controls the hatching rhythm in Bombyx mori via negative feedback loop of the circadian oscillator

Hatching behavior is a key target in silkworm (Bombyx mori) rearing, especially for the control of Lepidoptera pests. According to previous research, hatching rhythms appear to be controlled by a clock mechanism that restricts or "gates" hatching to a particular time. However, the underlying mechanism remains elusive. Under 12-h light:12-h dark photoperiod (LD) conditions, the transcriptional levels of the chitinase5 (Cht5) and hatching enzyme-like (Hel) genes, as well as the enzymatic activities of their gene products, oscillated in time with ambient light cycles, as did the transcriptional levels of the cryptochrome 1, cryptochrome 2, period (per), and timeless genes, which are key components of the negative feedback loop of the circadian rhythm. These changes were related to the expression profile of the ecdysteroid receptor gene and the hatching behavior of B. mori eggs. However, under continuous light or dark conditions, the hatching behavior, the expression levels of Cht5 and Hel, as well as the enzymatic activities of their gene products, were not synchronized unlike under LD conditions. In addition, immunohistochemistry experiments showed that light promoted the translocation of PER from the cytoplasm to the nucleus. In conclusion, LD cycles regulate the hatching rhythm of B. mori via negative feedback loop of the circadian oscillator.

Cloning and molecular characterization of BumaMPs1, a novel metalloproteinases from the venom of scorpion Buthus martensi Karsch

Scorpion venoms metalloproteinase is involved in a number of important biological, physiological and pathophysiological processes. In this work, a complete sequence of metalloproteinase was first obtained from venom of scorpion Buthus martensi and named as BumaMPs1. BumaMPs1 has 393 amino acid residues containing with a molecular mass of 44.53 kDa, showing an isoelectric point of 5.66. The primary sequence analysis indicated that the BumaMPs1 contains a zinc-binding motif (HELGHNLGISH), methionine-turn motif (YIM), disintegrin-like domain (ETCD) and N-glycosylation site. The multiple alignment of its deduced amino acid sequence and those of other metalloproteinase showed a high structural similarly, mainly among class reprolysin proteases. The phylogenetic analysis showed early divergence and independent evolution of BumaMPs1 from other metalloproteinase.

Molecular Expression of the Scribble Complex Genes, Dlg, Scrib and Lgl, in Silkworm, Bombyx mori

The Scribble protein complex genes, consisting of lethal giant larvae (Lgl), discs large (Dlg) and scribble (Scrib) genes, are components of an evolutionarily conserved genetic pathway that links the cell polarity in cells of humans and Drosophila. The tissue expression and developmental changes of the Scribble protein complex genes were documented using qRT-RCR method. The Lgl and Scrib genes could be detected in all the experimental tissues, including fat body, midgut, testis/ovary, wingdisc, trachea, malpighian tubule, hemolymph, prothoracic gland and silk gland. The Dlg gene, mainly expressed only in testis/ovary, could not be detected in prothoracic gland and hemolymph. In fat body, there were two higher expression stages of the three genes. The highest peak of the expression of the Lgl and Scrib genes in wingdisc lay at the 1st day of the 5th instar, but the Dlg gene was at 3rd day of 5th instar. The above results indicate that Scribble complex genes are involved in the process of molting and development of the wingdisc in the silkworm. This will be useful in the future for the elucidation of the detailed biological function of the three genes Scrib, Dlg and Lgl in B. mori.