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Associate Professor |
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Research Field |
Life Science / Ecology and environment |
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Graduating School 【 display / non-display 】
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Tokyo Metropolitan University Faculty of Science Graduated
1998.4 - 2002.3
Graduate School 【 display / non-display 】
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Ehime University Graduate School, Division of Agricltural Sciences Doctor's Course Completed
2004.4 - 2008.2
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The University of Tokyo Graduate School, Division of Science Master's Course Completed
2002.4 - 2004.3
Campus Career 【 display / non-display 】
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KONAN UNIVERSITY Faculty of Science and Engineering Faculty of Science and Engineering Department of Biology Associate Professor
2014.4
External Career 【 display / non-display 】
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独立行政法人日本学術振興会
2011.4 - 2013.3
Country：Japan
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自然科学研究機構生理学研究所
2010.9 - 2011.3
Country：Japan
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自然科学研究機構基礎生物学研究所
2008.4 - 2010.8
Country：Japan
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独立行政法人日本学術振興会
2005.4 - 2007.3
Country：Japan
Papers 【 display / non-display 】
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Near-anoxia induces immobilization and sustains viability of sperm stored in ant queens Reviewed
Ayako Gotoh, Mika Takeshima, Ken-ichi Mizutani
Scientific Reports 13 ( 1 ) 2023.3
Authorship：Lead author, Corresponding author Publisher：Springer Science and Business Media LLC
Abstract
After copulation, insect females store sperm in a spermatheca for some duration until fertilization. At the beginning of their adult lives, ant queens can preserve numerous viable sperm cells from copulation for over ten years. However, the key factors influencing long-term sperm storage have not been identified. Here we show that the spermathecal environment is nearly anoxic, which induces sperm immobilization. Furthermore, mitochondrial respiratory inhibitors suppress sperm motility, suggesting that sperm immobilization may be caused by a shortage of ATP generated from only glycolysis under near-anoxic conditions. Sperm immobilization is not induced by acidification via glycolytic metabolism because the spermathecal fluid is not acidic. Finally, we show that artificial anoxic conditions rather than aerobic conditions sustain viable sperm cells. Therefore, near-anoxia is a key factor influencing long-term sperm storage in ant queens. The viability of sperm cells under artificial anoxia, however, is lower than that of those dissected immediately from queens. Moreover, the immotile sperm cells under more than 4 h of anoxia do not begin swimming after aerobic exposure, unlike those under anoxic conditions for less than 2 h. This finding indicates that factors other than anoxia are also necessary for long-term sperm preservation.DOI： 10.1038/s41598-023-29705-7
Other Link： https://www.nature.com/articles/s41598-023-29705-7
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Ayako Gotoh
bioRxiv 2022.11
Authorship：Lead author, Corresponding author Publisher：Cold Spring Harbor Laboratory
Ant queens can maintain a large number of sperm cells for over a decade after mating at the beginning of their adult lives until they die. This ability is prominent because sperm cells cannot maintain their fertilization ability long after ejaculation in animals; however, the cellular mechanisms remain unclear. Sperm cells are maintained in the female sperm storage organ, the spermatheca, which supplies a suitable environment for sperm cells. To reveal the molecular basis of the long-term sperm storage mechanisms in ant queens, protein profiles enriched in the spermathecal fluid relative to the hemolymph were identified inLasius japonicususing mass spectrometry-based proteomics. Proteins related to the extracellular matrix, antioxidant, metabolic pathways, proteases, and with uncharacterized functions were enriched in the spermathecal fluid relative to the hemolymph. These enriched proteins were shared with highly expressed genes previously detected by transcriptome analyses of the spermatheca in queens ofCrematogaster osakensisbelonging to a different subfamily thanL. japonicus. It is considered that the ability for long-term sperm storage has evolved in the early ant lineage; therefore, the common proteins identified in the two ant species are crucial for this ability.
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Morphology of immatures of the thelytokous ant, Monomorium triviale Wheeler (Formicidae: Myrmicinae: Solenopsidini) with descriptions of the extraordinary last-instar queen larvae Reviewed
NAOTO IDOGAWA, AYAKO GOTOH, SHIGETO DOBATA
Zootaxa 5105 ( 2 ) 253 - 268 2022.3
Publisher：Magnolia Press
The ant genus Monomorium is one of the most species-rich but taxonomically problematic groups in the hyperdiverse subfamily Myrmicinae. An East Asian species, M. triviale Wheeler, produces both reproductive queens and sterile workers via obligate thelytokous parthenogenesis. Here, we describe the immature forms of M. triviale based on light and scanning electron microscopy observations, with a note on the striking caste dimorphism in the last larval instar. The last-instar queen larvae were easily recognized by their large size, “aphaenogastroid” body shape, and rows of doorknob-like tubercles on the lateral and dorsal body surface. This type of queen-specific structure has not been found in ants in general, let alone congeneric species found in Japan. In stark contrast to the queen larvae, worker larvae showed a “pheidoloid” body shape and a body surface similar to other ants. The worker larvae were estimated to have three instars, consistent with previously described congeners. The pupae of both castes had no cocoon, a characteristic commonly described in other Myrmicinae species. In total, the developmental period from egg to adult worker averaged 59 days under 25°C. We discuss possible functions of the tubercles of queen larvae based on previous studies.
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Caste differentiation of spermatheca and organs related to sperm use and oviposition in the honeybee, Apis mellifera
Ayako Gotoh, Ken Sasaki
Apidologie 52 ( 1 ) 262 - 271 2021
Joint Work
© 2020, INRAE, DIB and Springer-Verlag France SAS, part of Springer Nature. Striking queen–worker dimorphism associated with each task is a key feature of highly eusocial insects, including Apis mellifera. The present study histologically examined the developmental process of the internal reproductive organs including spermatheca, valve-fold in the vagina, semi-circular muscle surrounding the common oviduct, and abdominal ganglia in honeybee queens and workers. During the pupal stage, queens showed an increased spermathecal reservoir, development of the tracheal network surrounding the spermathecal reservoir, and elongation of the spermathecal gland. Compared with queens, these developmental processes were never observed during the pupal stage in workers. Moreover, development of the valve-fold and semi-circular muscle was aborted, and they became rudimentary at the middle pupal stage in workers. Morphological caste differences in the abdominal ganglia were observed from the prepupal stages, showing that the most posterior ganglion was fused with the anterior ganglia in queens but not in workers.
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A. Gotoh, S. Shigenobu, S. Shigenobu, K. Yamaguchi, S. Kobayashi, F. Ito, K. Tsuji
Insect Molecular Biology 27 212 - 220 2018.4
Joint Work
© 2017 The Royal Entomological Society In insects, seminal fluid proteins that are produced by male accessory glands and transferred to females during mating have key functions in sperm competition and sperm physiology that lead to male reproductive success. In ants, male reproductive success also depends on the longevity of sperm stored in the queen's spermatheca because their sexual offspring are usually produced only after a prolonged storage period. We identified genes that were up-regulated in the male accessory glands relative to the bodies of Crematogaster osakensis to characterize the reproductive molecules associated with male reproductive success in ants. We found novel genes that had no hits in a homology search and that were predominantly expressed in the accessory glands. These reproductive proteins may have evolved under rapid positive selection for reproductive success in the species. Furthermore, we discovered that three spermatheca-specific genes of C. osakensis queens were also enriched in the accessory glands relative to the bodies of males. These genes may be important for maintaining the sperm quality continuously from ejaculation by males to prolonged storage by queens. This research provides crucial information about the molecular mechanisms of sperm maintenance and sexual selection in ants, and also insight into the evolution of reproductive strategies in insects.
DOI： 10.1111/imb.12364