【作者】 王国栋；

【导师】 相建海； 刘保忠；

【作者基本信息】 中国科学院研究生院（海洋研究所） ， 海洋生物学， 2006， 博士

【摘要】 大部分贝类幼虫在发育过中要经历从浮游生活到底栖生活的变化过程,同时形态结构也要经历巨大的变化,这个过程称为变态。变态是文蛤幼虫发育过程中非常重要的一个阶段。药理学和细胞免疫学证据表明β肾上腺素样受体在文蛤幼虫变态过程中有重要作用。药理学实验分别采用了几种儿茶酚胺类受体的激动剂和抑制剂来处理幼虫,检验它们在幼虫变态过程中的作用。结果表明,在10μM和100μM的浓度下,肾上腺素(AD)和去甲肾上腺素(NA)中能够显著提高幼虫的变态率(p<0.05)。10μM和100μM浓度的AD能够提高幼虫变态率30%左右。10μM和100μM浓度的NA能分别提高幼虫变态率35.3%和27.6%。10μM的β受体激动剂-isoproterenol也能够显著的提高幼虫的变态率30%(p<0.05),但是α受体激动剂-phenylephrine在0.1μM到100μM的浓度范围内不能显著提高幼虫的变态率(p>0.05)。而且,1μM的β受体抑制剂-propanolol能显著的抑制AD或NA提高幼虫变态率的作用(p<0.05);但是α受体抑制剂-prazosin对AD或NA提高幼虫变态率没有显著性影响(p>0.05)。此外本文还利用整装免疫细胞化学的方法进一步研究了文蛤幼虫不同发育阶段,神经系统和β肾上腺素样受体的发育情况。幼虫的神经系统在担轮幼虫时期(受精后18h)开始发育,这时还不能检测到β肾上腺素受体。面盘幼虫时期(受精后1d)具备了顶神经节、脑神经节和脏神经节组成的中枢神经系统,在口附近有一些外周神经。β肾上腺素受体在受精后24h首次出现在面盘幼虫的顶神经节和脑神经节,分别命名为AR(apical receptor)和CR1(cerebral receptor 1)。在受精后5d顶神经节已经检测不到。脑神经节和脏神经节由腹部向背部迁移,口的背腹两侧都出现了一些神经元。并且脏神经节周围也出现了一些神经细胞。AR在受精后3d就检测不到了。同时在CR1的后部新出现了一些β肾上腺素受体,命名为CR2。此后CR2发育迅速,在受精后5d就和CR1差不多大小。并且在CR1和CR2之间还出现了很多小的更多还原

【Abstract】 Metamorphose is an important developmental stage during Meretrix meretix ontogeny.Manypharmacological experiments have been conducted to determine the effects of adrenergic agonistand antagonist of catecholamine receptors on Meretrix meretrix metamorphosis. Results showedthat adrenaline (AD) and noradrenaline (NA) had substantial effects (p<0.05) on larvalmetamorphosis at concentrations ranging from 10μM to 100μM. 10μM β-adrenergic receptor (AR)agonist isoproterenol showed the same inducement effect as that of NA and AD on metamorphosis,whereas the α-AR agonist phenylephrine had no significant effect at concentrations between0.1μM and 100μM concentrations (p>0.05). Furthermore, 1 μM β-AR antagonist propanolol, butnot α-AR antagonist prazosin, depressed the larval metamorphosis induced by NA or AD. Theresults of pharmacology suggest that β-adrenergic-like receptor might play a considerable role inthe larval metamorphosis of M. meretrix by AD or NA.Moreover, we investigated the development of beta adrenergic receptor and nervous system bywhole mount immunocytochemistry technique. The results showed larval nervous system firstappeared during late trochophore larva stage (18 hours post fertilization), and beta adrenergicreceptor was not detected. At 1 day post fertilization, there appeared apical ganglion, cerebralganglion, visceral ganglion and some neurons near the mouth. And at the same time, betaadrenergic receptor appeared in the apical ganglion and cerebral ganglion, named AR (apicalreceptor) and CR1 (cerebral receptor 1) respectively.At 5dpf, it was difficult to detect the immunoreactive signal of apical ganglion. The cerebralganglion and visceral ganglion leaved from the velum to the dorsal. There appeared twoimmunoreactive cell bodies in ventral and dorsal to the mouth. And there were someimmunoreactive cells around the visceral ganglion. AR was not detected and CR2 appeared in theposterior of CR1 at 3dpf. And CR2 developed quickly. At 5dpf, the size of CR2 was similar to theCR1. Moreover, many little immunoreative dots were around CR1 and CR2.After metamorphosis (7dpf), the apical ganglion disappeared and there appeared pedalganglion in the foot. Moreover, there appeared some peripheral neurons in the mantle. Exceptjuvenile cerebral ganglion and visceral ganglion, beta adrenergic receptor was detected in thejuvenile pedal, mantle and siphon. The result of western blot showed that beta adrenergic receptorwas detected in the adult gill, pedal, heart, siphon, lip and mantle.After the metamorphosis signal reached the target organs, the larval morphology andbehaviour changed. Whole mount technique using fluorescent-labelled phalloidin for actinstaining was applied to investigate the ontogeny of the various muscular systems during larvaldevelopment in the clam Meretrix meretrix. Larval shell retractor muscles (LR) and anterioradductor (A-AD) were the first detectable muscle structure in the later trochophore larva (18 hourspost fertilization). Soon after, trochophore larva developed into veliger larva. And the larvalmuscular system developed fully at 22 hpf. There were 5 pairs of LR, named LR1-LR5 fromanterior to posterior respectively. The LR1-4 had a dendritic progress the venter, and the dendritesprojected into the velum region, thus formed velum muscle ring (VR). The anterior adductorbecame two muscular fibers, and the ventral part was bigger. The overall morphology of muscularsystems during the whole veliger stage (1-5 dpf) was same, except became stronger day by day.During metamorphosis (6-7 dpf), the VR collapses, and then disappears completely. The LRatrophied and contracted to the ventral gradually and also disappeared. And there appeared threemuscular structures, pedal retractor (PR), posterior adductor (P-AD), and mantle muscle (MM).The PR was composed of two muscular fibers, whose fine dendrites formed reseau muscularstructure in the foot. The P-AD was composed two fibers and similar to the A-AD. The MMextended from the A-AD to the P-AD, which comprised 2 long anterior-posterior muscular fibersand many short left-right muscular fibers.After metamorphosis, the postlarval muscle system was simpler because of thedisappearance of the larval muscle system. There were only adductors, pedal rectractors andmantle muscle, which compose the adult muscle system.更多还原