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Diapause is a state of developmental arrest that is most often observed in arthropods, especially insects. The domesticated silkworm, Bombyx mori, is a typical insect that enters diapause at an early embryonic stage. Previous studies have revealed that the diapause hormone (DH) signaling molecules, especially the core members DH and DH receptor 1 (DHR1), are crucial for the determination of embryonic diapause in diapause silkworm strains. However, whether they function in non-diapause silkworm strains remains largely unknown. Here, we generated two transgenic lines overexpressing DH or DHR1 genes in a non-diapause silkworm strain, Nistari. Our results showed that developmental expression patterns of DH and DHR1 are quite similar in transgenic silkworms: both genes are highly expressed in the mid to late stages of pupae and are most highly expressed in day-6 pupae but are expressed at very low levels in other developmental stages. Moreover, the overexpression of DH or DHR1 can affect the expression of diapause-related genes but is not sufficient to induce embryonic diapause in their offspring. This study provides new insights into the function of DH and DHR1 in a non-diapause silkworm strain.
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http://dx.doi.org/10.1007/s11248-017-0045-y | DOI Listing |
Int J Mol Sci
August 2025
Institute of Agrobiological Sciences, National Agriculture and Food Research Organization, 1-2 Owashi, Tsukuba 305-8634, Japan.
In general, the silkworm, , has a diapause trait in its eggs. Therefore, transgenic silkworm can be produced by embryonic microinjection using eggs laid by a non-diapause strain in In this study, we performed microinjection using eggs of diapause strains which have good characteristics for industrial use, such as a big cocoon, thin and smooth silk, and tolerance against disease due to the growing industrial use of transgenic silkworms. For the conversion of egg diapause traits from diapause to non-diapause types, we used anti-serum against the diapause hormone of (BmDH), which was injected into maternal pupae, producing non-diapause eggs at a high rate.
View Article and Find Full Text PDFArch Insect Biochem Physiol
July 2025
College of Animal Science, South China Agricultural University, Guangzhou, China.
Acid soaking with hydrochloric acid (HCl) is a common method used to prevent or break diapause in silkworm eggs and has been widely applied in production. However, its underlying mechanism remains to be explored. Few studies have reported on the metabolism of mono- or disaccharides, and the differential expression patterns of genes and proteins related to the phosphatidyl inositol 3-kinase (PI3K/)Akt signaling pathway across the stages of silkworm diapause eggs, non-diapause eggs, instant acid-soaked eggs, and red bean color acid-soaked (RBCAS) eggs.
View Article and Find Full Text PDFBMC Genomics
July 2025
State Key Laboratory of Resource Insects, Southwest University, Chongqing, China.
Unlabelled: Microsporidia are a group of intracellular and unicellular eukaryotic parasites, which can nearly infect all animals, including human beings. As the first identified microsporidia, is a world-wide threat for silkworm eggs production, it can cause the congenital infection transovarial transmission. It is important for pathogenesis elucidation to unravel the molecular characteristics of proliferation and host immune responses to the congenital infection in embryo and larva stage.
View Article and Find Full Text PDFInsects
March 2025
State Key Laboratory of Resource Insects, Institute of Sericulture and Systems Biology, Southwest University, Chongqing 400715, China.
In insects, the number of life cycles varies inter- and intra-specifically, and it is widely accepted that the variation in the number of life cycles is an adaptive response to diverse environmental conditions. However, the molecular mechanism that underlies the variety and plasticity in the number of life cycles is largely unknown. In the silkworm, , the () locus has three alleles, (univoltine; dominant), (bivoltine; standard), and (polyvoltine; recessive), which are known to generate variation in the number of life cycles in a year under natural conditions, with obligatory diapause for the allele, facultative diapause for , and non-diapause for .
View Article and Find Full Text PDFInsects
December 2024
Department of Biology, National Museum of Natural Science, 1 Kuan-Chien Road, Taichung 404, Taiwan.
In the present study, we investigated the possible correlation between insulin/ecdysone signaling and chilling-induced egg diapause termination in . Changes in () and () gene expression levels in chilled eggs (whose diapause had been terminated by chilling to 5 °C for 90 days) exhibited no significant increase after being transferred to 25 °C, which differed from both non-diapause eggs and HCl-treated eggs. We further compared the differential temporal expressions of (, -, and ), ( and ), and ( () and ()) as well as () genes between chilled eggs and eggs kept at 25 °C.
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