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2 results on '"Hiroki Gotoh"'

1. Dimorphic sperm formation by Sex-lethal

Author

Hiroki Gotoh, Hiroyuki Oshima, Hiroki Sakai, Teruyuki Niimi, Toshinobu Yaginuma, Takaaki Daimon, Ken Sahara, and Kodai Yuri

Subjects
0106 biological sciences, 0301 basic medicine, Male, endocrine system, sex determination, Moths, 010603 evolutionary biology, 01 natural sciences, Oogenesis, apyrene sperm, Germline, 03 medical and health sciences, Spermatheca, Bombyx mori, Drosophilidae, Melanogaster, Animals, Drosophila Proteins, Spermatogenesis, reproductive and urinary physiology, sperm polymorphism, Multidisciplinary, biology, urogenital system, fungi, RNA-Binding Proteins, Sex-lethal, Biological Sciences, Sex Determination Processes, biology.organism_classification, Bombyx, Sperm, Spermatozoa, Cell biology, 030104 developmental biology, Drosophila melanogaster, Fertility, Female, Butterflies, Developmental Biology
Abstract

Significance Sperm exhibit dramatic evolutionarily divergent morphologies in almost all taxa. Some sexually reproductive species show polymorphisms in the sperm produced by single males. Here, we focused on Sex-lethal (Sxl), which is the master sex-determination gene in Drosophila melanogaster, and investigated its function in the lepidopteran insect Bombyx mori. Our genetic analyses revealed that Sxl is essential for the formation of anucleate nonfertile parasperm. It is not expected that Sxl would be involved in sperm polymorphisms. Yet, whereas many morphological observations and ecological surveys have been conducted on sperm polymorphisms, this paper identifies the gene involved in sperm polymorphisms. Moreover, we clearly demonstrate that parasperm of B. mori is necessary for sperm migration in female organs., Sex is determined by diverse mechanisms and master sex-determination genes are highly divergent, even among closely related species. Therefore, it is possible that homologs of master sex-determination genes might have alternative functions in different species. Herein, we focused on Sex-lethal (Sxl), which is the master sex-determination gene in Drosophila melanogaster and is necessary for female germline development. It has been widely shown that the sex-determination function of Sxl in Drosophilidae species is not conserved in other insects of different orders. We investigated the function of Sxl in the lepidopteran insect Bombyx mori. In lepidopteran insects (moths and butterflies), spermatogenesis results in two different types of sperm: nucleated fertile eupyrene sperm and anucleate nonfertile parasperm, also known as apyrene sperm. Genetic analyses using Sxl mutants revealed that the gene is indispensable for proper morphogenesis of apyrene sperm. Similarly, our analyses using Sxl mutants clearly demonstrate that apyrene sperm are necessary for eupyrene sperm migration from the bursa copulatrix to the spermatheca. Therefore, apyrene sperm is necessary for successful fertilization of eupyrene sperm in B. mori. Although Sxl is essential for oogenesis in D. melanogaster, it also plays important roles in spermatogenesis in B. mori. Therefore, the ancestral function of Sxl might be related to germline development.

Published
2019

2. Genomic and transcriptomic analyses of the subterranean termite Reticulitermes speratus: Gene duplication facilitates social evolution.

Author

Shuji Shigenobu, Yoshinobu Hayashi, Dai Watanabe, Gaku Tokuda, Hojo, Masaru Y., Kouhei Toga, Ryota Saiki, Hajime Yaguchi, Yudai Masuoka, Ryutaro Suzuki, Shogo Suzuki, Moe Kimura, Masatoshi Matsunami, Yasuhiro Sugime, Kohei Oguchi, Teruyuki Niimi, Hiroki Gotoh, Hojo, Masaru K., Satoshi Miyazaki, and Atsushi Toyoda

Subjects
CHROMOSOME duplication, SOCIAL evolution, GENOMICS, TERMITES, ANIMAL industry
Abstract

Termites are model social organisms characterized by a polyphenic caste system. Subterranean termites (Rhinotermitidae) are ecologically and economically important species, including acting as destructive pests. Rhinotermitidae occupies an important evolutionary position within the clade representing a transitional taxon between the higher (Termitidae) and lower (other families) termites. Here, we report the genome, transcriptome, and methylome of the Japanese subterranean termite Reticulitermes speratus. Our analyses highlight the significance of gene duplication in social evolution in this termite. Gene duplication associated with caste-biased gene expression was prevalent in the R. speratus genome. The duplicated genes comprised diverse categories related to social functions, including lipocalins (chemical communication), cellulases (wood digestion and social interaction), lysozymes (social immunity), geranylgeranyl diphosphate synthase (social defense), and a novel class of termite lineage-specific genes with unknown functions. Paralogous genes were often observed in tandem in the genome, but their expression patterns were highly variable, exhibiting caste biases. Some of the assayed duplicated genes were expressed in caste-specific organs, such as the accessory glands of the queen ovary and the frontal glands of soldier heads. We propose that gene duplication facilitates social evolution through regulatory diversification, leading to caste-biased expression and subfunctionalization and/or neofunctionalization conferring caste-specialized functions. [ABSTRACT FROM AUTHOR]

Published
2022
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