权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Analyses of physiological factors regulating oocyte maturation and early development of a hermaphrodite pond snail Lymnaea stagnalis

雌雄同体池塘蜗牛Lymnaea stagnalis卵母细胞成熟和早期发育的生理因素分析

基本信息

批准号：
11660185
负责人：
OSHIRO Takashi
金额：
$ 1.28万
依托单位：
Tokyo University of Fisheries
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

项目摘要

(1) Snails could be stimulated to oviposit egg-mass within 3h by their transfer from polluted stagnant water into clean aerated one. MALDI-MS analysis revealed that caudo-dorsal cell hormone (CDCH) were released from cerebral commissure(COM) into haemolymph (HL) within 30 min after transfer. The crude extracts of COM with dorsal bodies (DB) could induce in vitro gamete-release(oocytes and sperm) from the dissected ovotesis-digestive gland complex.(2) Ovulated oocytes soon appeared, moved and fertilized in the distal part of spermoviduct (DSO). Meiosis and cleavage could be induced by immersing DSO oocytes in snail saline, HL and distilled water, while they were strictly inhibited in vivo till spawning. Isolated oocytes just spawned with capsule (egg membrane + perivitelline fluid) could show polar body formation and cleavage in hypotonic solution of mannitol but in hypertonic ones they could not. Immersion test showed that most osmolytes with low molecular weight immediately penetrate the capsule, which always keep perivitelline fluid hypertonic than HL by inner colloid osmotic pressure. This seems to be the major reason why oocyte meiosis can never be allowed before spawning.(3) Immersion of spawning snails in 10^<-3>〜10^<-1>M solution of β-ecdysone slightly increased the whole volume of egg capsule. Formation of perivitelline fluid may be stimulated by this steroid.(4) Complementary DNA of ecdysone receptor was not obtained by RT-PCR from the extract of the reproductive tract of mature snails.(5) HPLC-EIA demonstrated that β-ecdysone level in HL reached the peak at the early phase of oocyte-packaging (at the secretion of albumen gland) and rapidly decreased. Alpha-ecdysone level gradually increased and showed the peak around spawning time. Then β-ecdysone may play an important role in preventing meiosis through the formation of perivitelline fluid.

(1)将钉螺从污染的死水中转移到干净的通气水体中，可在3 h内刺激钉螺产卵。MALDI-MS分析显示，尾背细胞激素（CDCH）在转移后30分钟内从大脑连合（COM）释放到血淋巴（HL）中。COM的粗提物与背体（DB）可以诱导在体外释放配子（卵母细胞和精子）从解剖的排卵消化腺复合体。(2)排卵后的卵母细胞很快在精子管远端出现、移动并受精。用蜗牛盐水、HL和蒸馏水浸泡DSO卵母细胞可诱导减数分裂和卵裂，而在体内则受到严格抑制，直至产卵。分离的卵母细胞在低渗甘露醇溶液中能形成极体并发生卵裂，而在高渗甘露醇溶液中则不能。浸泡试验表明，大多数低分子量渗透剂能迅速穿透被膜，通过内部胶体渗透压使卵黄周液始终保持高于HL的高渗状态。这似乎是卵母细胞减数分裂在产卵前不能进行的主要原因。(3)将产卵螺浸泡在10 <-3>~ 10 μ <-1>M β-蜕皮激素溶液中，卵囊的总体积略有增加。这种类固醇可以刺激卵周液的形成。(4)从成熟钉螺生殖道提取液中未获得蜕皮激素受体的互补DNA。(5)HPLC-EIA结果显示，HL中β-蜕皮激素水平在卵母细胞包装早期（蛋白腺分泌期）达到高峰，随后迅速下降。α-蜕皮激素水平逐渐升高，在产卵前后达到峰值。因此，β-蜕皮激素可能通过形成卵黄周液而阻止减数分裂。