title: Lactic acid is a sperm motility inactivation factor in the sperm storage tubules.
abstract: Although successful fertilization depends on timely encounters between sperm and egg, the decoupling of mating and fertilization often confers reproductive advantages to internally fertilizing animals. In several vertebrate groups, postcopulatory sperm viability is prolonged by storage in specialized organs within the female reproductive tract. In birds, ejaculated sperm can be stored in a quiescent state within oviductal sperm storage tubules (SSTs), thereby retaining fertilizability for up to 15 weeks at body temperature (41°C); however, the mechanism by which motile sperm become quiescent within SSTs is unknown. Here, we show that low oxygen and high lactic acid concentrations are established in quail SSTs. Flagellar quiescence was induced by lactic acid in the concentration range found in SSTs through flagellar dynein ATPase inactivation following cytoplasmic acidification (<pH 6.0). The long-term preservation of sperm morphology under hypoxic and high temperature conditions indicates that a combination of these factors enables sperm cells to survive during the ovulation cycles. Our findings suggested a novel physiological role for lactic acid in promoting sperm quiescence in SSTs and opened up a new opportunity for technological improvement in prolonging sperm longevity at ambient or body temperature.
authors.affiliation: Department of Applied Biological Chemistry, Faculty of Agriculture, Shizuoka University, 836 Ohya, Shizuoka, Shizuoka 422-8529, Japan.|United Graduate School of Agricultural Science, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan.
authors.forename: Mei
authors.initials: M
authors.lastname: Matsuzaki
authors.affiliation: Department of Applied Biological Chemistry, Faculty of Agriculture, Shizuoka University, 836 Ohya, Shizuoka, Shizuoka 422-8529, Japan.
authors.forename: Shusei
authors.initials: S
authors.lastname: Mizushima
authors.affiliation: Department of Applied Biological Chemistry, Faculty of Agriculture, Shizuoka University, 836 Ohya, Shizuoka, Shizuoka 422-8529, Japan.
authors.forename: Gen
authors.initials: G
authors.lastname: Hiyama
authors.affiliation: Oki Marine Biological Station, Education and Research Center for Biological Resources, Faculty of Life and Environmental Science, Shimane University, 194 Kamo, Okinoshima-cho, Oki, Shimane 685-0024, Japan.
authors.forename: Noritaka
authors.initials: N
authors.lastname: Hirohashi
authors.affiliation: Shimoda Marine Research Center, University of Tsukuba, 5-10-1 Shimoda, Shizuoka 415-0025, Japan.
authors.forename: Kogiku
authors.initials: K
authors.lastname: Shiba
authors.affiliation: Shimoda Marine Research Center, University of Tsukuba, 5-10-1 Shimoda, Shizuoka 415-0025, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Inaba
authors.affiliation: Research Institute of Green Science and Technology, Shizuoka University, 836 Ohya, Shizuoka, Shizuoka 422-8529, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Suzuki
authors.affiliation: Research Institute of Green Science and Technology, Shizuoka University, 836 Ohya, Shizuoka, Shizuoka 422-8529, Japan.
authors.forename: Hideo
authors.initials: H
authors.lastname: Dohra
authors.affiliation: Department of Applied Biological Chemistry, Faculty of Agriculture, Shizuoka University, 836 Ohya, Shizuoka, Shizuoka 422-8529, Japan.|Research Institute of Green Science and Technology, Shizuoka University, 836 Ohya, Shizuoka, Shizuoka 422-8529, Japan.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Ohnishi
authors.affiliation: Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.
authors.forename: Yoshikatsu
authors.initials: Y
authors.lastname: Sato
authors.affiliation: Department of Applied Biological Chemistry, Faculty of Agriculture, Shizuoka University, 836 Ohya, Shizuoka, Shizuoka 422-8529, Japan.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Kohsaka
authors.affiliation: Department of Applied Biological Chemistry, Faculty of Agriculture, Shizuoka University, 836 Ohya, Shizuoka, Shizuoka 422-8529, Japan.
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Ichikawa
authors.affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Atsumi
authors.affiliation: Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.|Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Yoshimura
authors.affiliation: Department of Applied Biological Chemistry, Faculty of Agriculture, Shizuoka University, 836 Ohya, Shizuoka, Shizuoka 422-8529, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Sasanami
mesh_terms: D000825:Animal Structures / Q000378:metabolism*; D000818:Animals; D005260:Female; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000378:metabolism*; D008297:Male; D011784:Quail / Q000378:metabolism*; D013081:Sperm Motility / Q000502:physiology*; D013094:Spermatozoa / Q000378:metabolism*
chemical_list: D019344:Lactic Acid