Unuma Tatsuya, Sawaguchi Sayumi, Yamano Keisuke, Ohta Hiromi
Hokkaido National Fisheries Research Institute, Fisheries Research Agency, Kushiro, Hokkaido 085-0802, Japan.
Biol Bull. 2011 Oct;221(2):227-37. doi: 10.1086/BBLv221n2p227.
Sea urchins of both sexes store the nutrients necessary for gametogenesis in nutritive phagocytes of the agametogenic gonad. A zinc-binding protein termed the major yolk protein (MYP) is stored here as two isoforms: the egg-type (predominant in egg yolk granules) and the coelomic fluid-type (a precursor with greater zinc-binding capacity). MYP is used during gametogenesis as material for synthesizing gametic proteins and other components. We investigated its accumulation and relationship to zinc contents in gonads during the non-reproductive season in Pseudocentrotus depressus. MYP constituted most of the protein in coelomic fluid and gonads. Both ovaries and testes grew gradually, accumulating MYP and zinc during the year. Total zinc contents and the ratio of coelomic fluid-type to egg-type protein were higher in ovaries than in testes as gametogenesis approached. Most of the zinc in the coelomic fluid was bound to MYP, and the concentrations of MYP and zinc were elevated toward the onset of oogenesis in the female coelomic fluid. Thus, MYP accumulates in the agametogenic ovaries and testes during the non-reproductive season, playing a role as a carrier to transport zinc to the gonad. Transportation of zinc by MYP is more active in females than in males.
两性海胆在非配子生成性腺的营养吞噬细胞中储存配子发生所需的营养物质。一种名为主要卵黄蛋白（MYP）的锌结合蛋白以两种同工型储存在这里：卵型（主要存在于卵黄颗粒中）和体腔液型（一种具有更大锌结合能力的前体）。MYP在配子发生过程中用作合成配子蛋白和其他成分的原料。我们研究了在非繁殖季节平背刺海胆性腺中MYP的积累及其与锌含量的关系。MYP构成了体腔液和性腺中大部分蛋白质。卵巢和精巢全年都在逐渐生长，积累MYP和锌。随着配子发生的临近，卵巢中的总锌含量以及体腔液型与卵型蛋白的比例高于精巢。体腔液中的大部分锌与MYP结合，并且在雌性体腔液中，随着卵子发生的开始，MYP和锌的浓度升高。因此，MYP在非繁殖季节在非配子生成的卵巢和精巢中积累，作为将锌运输到性腺的载体发挥作用。MYP对锌的运输在雌性中比在雄性中更活跃。
