title: Proteomics of ionomycin-induced ascidian sperm reaction: Released and exposed sperm proteins in the ascidian Ciona intestinalis.
abstract: Sperm proteins mediating sperm-egg interaction should be exhibited on the sperm surface, or exposed or released when sperm approach an egg. In ascidians (protochordates), sperm undergo a sperm reaction, characterized by enhanced sperm motility and mitochondrial swelling and shedding on contact with the vitelline coat (VC) or by treatment with Ca(2+) ionophore. Here, proteomic analysis was conducted on sperm exudates and sperm surface proteins using ionomycin-induced sperm reaction and cell-impermeable labeling in Ciona intestinalis type A (C. robusta). In the exudate from sperm treated with ionomycin, membrane proteins including a possible VC receptor CiUrabin were abundant, indicating the release of membranous compartments during sperm reaction. Among the surface proteins XP_009859314.1 (uncharacterized protein exhibiting homology to HrTTSP-1) was most abundant before the sperm reaction, but XP_004227079.1 (unknown Ig superfamily protein) appears to be most abundantly exposed by the sperm reaction. Moreover, proteins containing a notable set of domains, astacin-like metalloprotease domain and thrombospondin type 1 repeat(s), were found in this fraction. Possible roles in fertilization as well as localizations and behaviors of these proteins are discussed.
authors.affiliation: Sugashima Marine Biological Laboratory, Graduate School of Science, Nagoya University, Sugashima, Toba, Japan.
authors.forename: Shiori
authors.initials: S
authors.lastname: Nakazawa
authors.affiliation: Sugashima Marine Biological Laboratory, Graduate School of Science, Nagoya University, Sugashima, Toba, Japan.
authors.forename: Maki
authors.initials: M
authors.lastname: Shirae-Kurabayashi
authors.affiliation: Sugashima Marine Biological Laboratory, Graduate School of Science, Nagoya University, Sugashima, Toba, Japan.
authors.forename: Kei
authors.initials: K
authors.lastname: Otsuka
authors.affiliation: Sugashima Marine Biological Laboratory, Graduate School of Science, Nagoya University, Sugashima, Toba, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Sawada
mesh_terms: D000818:Animals; D061207:Calcium Ionophores / Q000494:pharmacology; D002938:Ciona intestinalis / Q000187:drug effects / Q000378:metabolism*; D015759:Ionomycin / Q000494:pharmacology*; D008297:Male; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D040901:Proteomics; D013094:Spermatozoa / Q000187:drug effects / Q000378:metabolism*; D025801:Ubiquitin / Q000378:metabolism
chemical_list: D061207:Calcium Ionophores; D025801:Ubiquitin; D015759:Ionomycin; D046988:Proteasome Endopeptidase Complex
keywords: Ascidian; Cell biology; Fertilization; Protease; Proteasome; Ubiquitin