title: Sneaker Male Squid Produce Long-lived Spermatozoa by Modulating Their Energy Metabolism.
abstract: Spermatozoa released by males should remain viable until fertilization. Hence, sperm longevity is governed by intrinsic and environmental factors in accordance with the male mating strategy. However, whether intraspecific variation of insemination modes can impact sperm longevity remains to be elucidated. In the squid Heterololigo bleekeri, male dimorphism (consort and sneaker) is linked to two discontinuous insemination modes that differ in place and time. Notably, only sneaker male spermatozoa inseminated long before egg spawning can be stored in the seminal receptacle. We found that sneaker spermatozoa exhibited greater persistence in fertilization competence and flagellar motility than consort ones because of a larger amount of flagellar glycogen. Sneaker spermatozoa also showed higher capacities in glucose uptake and lactate efflux. Lactic acidosis was considered to stabilize CO2-triggered self-clustering of sneaker spermatozoa, thus establishing hypoxia-induced metabolic changes and sperm survival. These results, together with comparative omics analyses, suggest that postcopulatory reproductive contexts define sperm longevity by modulating the inherent energy levels and metabolic pathways.
authors.affiliation: From the Oki Marine Biological Station, Education and Research Center for Biological Resources, Shimane University, Oki 685-0024, Japan, hiro@life.shimane-u.ac.jp.
authors.forename: Noritaka
authors.initials: N
authors.lastname: Hirohashi
authors.affiliation: the Research Institute, National Center for Global Health and Medicine, Tokyo 162-8655, Japan.
authors.forename: Miwa
authors.initials: M
authors.lastname: Tamura-Nakano
authors.affiliation: the Center for Science Education, Osaka Kyoiku University, Osaka 582-858, Japan, and.
authors.forename: Fumio
authors.initials: F
authors.lastname: Nakaya
authors.affiliation: From the Oki Marine Biological Station, Education and Research Center for Biological Resources, Shimane University, Oki 685-0024, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Iida
authors.affiliation: the Atmosphere and Ocean Research Institute, University of Tokyo, Chiba 277-8564, Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Iwata
mesh_terms: D000818:Animals; D049832:Decapodiformes / Q000378:metabolism*; D004734:Energy Metabolism / Q000502:physiology*; D008297:Male; D013094:Spermatozoa / Q000378:metabolism*
keywords: alternative reproductive tactics; cell motility; cephalopods; glucose metabolism; glycogen; male dimorphism; postcopulatory sexual selection; reproduction; spermatozoa