Effect of two different habitats on spine and gonad colour in the purple sea urchin Paracentrotus lividus

This study investigates the effect of different Mediterranean habitats on spine and gonad colouring and gonadal index in the purple sea urchin Paracentrotus lividus (Echinodermata: Echinoidea). Specimens were collected in winter 2012 in Posidonia oceanica meadows and rocky bottom areas at two sites in Southern Sardinia (Italy, Tyrrhenian Sea). Colorimetric analyses of spines and gonads were conducted with a digital colorimeter using CIELAB colour spaces, which defines the colour in terms of three coordinate values: lightness (L*), redness (a*) and yellowness (b*). Lightness and redness of the spines differed significantly between habitats, whereas colour spaces of the gonads did not. A careful analysis of the gonad index showed it to be significantly affected by habitat, registering higher values in rocky bottom locations. In conclusion, it seems that habitat does affect spine colour but not gonad colour. Spine colour seems to be site‐dependent, whereas the gonad index depends solely on the habitat.     

三倍体皱纹盘鲍(Haliotis discus Hannai)性腺发育的生物学研究

采用光镜和电镜方法，观察了吊笼式人工养殖三倍体皱纹盘鲍性腺发育情况，并与二倍体进行比较。结果表明，三倍体鲍性腺发育分期基本与二倍体相同，但雄性腺发育停止在生长期，雌性腺少数可达成熟期，没有发现排放期。三倍体鲍性腺发育较二倍体差，表观看其性腺薄，只包围肝胰腺1／3—1／2，颜色浅：7—10月间检查的86个二倍体个体中成熟期的占24．4％，休止期占11．6％。而83个三倍体个体中，成熟期占1．2％，休止期占72．3％。三倍体成熟卵母细胞直径、核径、线粒体直径、胶膜厚度较二倍体大，但卵黄颗粒、线粒体、粗面内质网等细胞器较二倍体少。     

Esterification of vertebrate-like steroids in the eastern oyster (Crassostrea virginica)

The esterification of two model vertebrate steroid hormones – estradiol (E2) and dehidroepiandrosterone (DHEA) – was studied in the oyster Crassostrea virginica. The activity of acyl-CoA:steroid acyltransferase was characterized in microsomal fractions isolated from oyster digestive glands. The apparent K_m and V_max values changed with the fatty acid acyl-CoA used (C20:4, C18:2, C18:1, C16:1, C18:0 or C16:0), and were in the range of 9–17 μM, and 35–74 pmol/min/mg protein for E2, and in the range of 45–120 μM, and 30–182 pmol/min/mg protein for DHEA. Kinetic parameters were also assessed in gonadal tissue. The enzyme saturated at similar concentrations, although conjugation rates were lower than in digestive gland. Preliminary data shows that tributyltin (TBT) in the low μM range (1–50) strongly inhibits E2 and DHEA esterification, the esterification of E2 being more sensitive to inhibition than that of DHEA. Overall, results indicate that apolar conjugation occurs in oysters, in both digestive gland and gonads, at a very similar rate to mammals, suggesting that this is a well conserved conjugation pathway during evolution. Esterification, together with other mechanisms, can modulate endogenous steroid levels in C. virginica, and might be a target for endocrine disrupters, such as TBT.     

埋植雄烯二酮一次诱导雄性日本鳗鲡性腺发育成熟的研究

埋植雄烯二酮包膜型药条一次后70d,塘养雄鳗成熟率达73．3％。鳗鲡精液质量随埋植天数的增加逐步提高;脑垂体促性腺激素（GtH）含量在埋植后有明显升高;血清GtH含量在理植后15d起,一直稳定在2ng／ml左右,与对照组（约0．9ng／ml）相比有显著提高。     

Reproductive biology of the leatherjacket,Meuschenia scaber (Monacanthidae) (Forster 1801) in the Hauraki Gulf,New Zealand

The leatherjacket Meuschenia scaber is widely distributed in Australasian waters, and is a valued bycatch of inshore bottom trawl fisheries although little is known of its life history. Here, we describe the reproductive biology of the species based on 651 leatherjackets sampled in the Hauraki Gulf, New Zealand, between July 2014 and March 2016. The maximum total length (L_T) recorded for females and males were 320 and 315?mm, respectively, with both sexes present in all size classes. Monthly analysis of gonad condition revealed a clear spawning season from late austral winter to early summer (August–December), and histological analysis of the ovaries revealed that M. scaber is an indeterminate serial spawning gonochorist. The estimated sizes at sexual maturity (L₅₀) for females (189.9?mm L_T) and males (188.4?mm L_T) did not differ significantly. Relatively small testes, sexual dimorphism and underwater observation of nesting suggest that M. scaber is a paired spawner.     

野生重口裂腹鱼[Schizothorax(Racoma) davidi(Sauvage)]的性腺发育观察与人工繁殖研究

对野生重口裂腹鱼[Schizothorax(Racoma) davidi(Sauvage)]的性腺发育观察与人工繁殖进行了研究。结果表明,重口裂腹鱼雄鱼3龄达到性成熟,而雌鱼5龄以上方达到性成熟,其性腺指数随着年龄增加而显著上升(P<0.05);雌鱼性腺指数、绝对怀卵量和卵径随着年龄和体重增加明显上升(P<0.05orP<0.01)。对24尾5、6龄雌、雄重口裂腹鱼采用二针注射法进行人工催产实验,平均采卵数为1.33万粒和2.02万粒,采精量为25.4ml和34.8ml。其平均卵子受精率和受精卵出膜时间分别为74.2%和77.1%、203h和227h[水温(16.2±0.9)℃],6龄雌鱼受精卵的卵径、卵重均明显高于5龄雌鱼,6龄雌鱼的受精卵孵化率为41.9%,明显高于5龄雌鱼的30.6%(P<0.05orP<0.01),选用年龄较大的雌鱼作为亲鱼,是保证人工繁殖获得良好效果的关键。     

尖刀蛏的生殖周期

本文是尖刀蛏Ｃｕｌｔｅｌｌｕｍ ｓｃａｌｐｒｕｍ（Ｇｏｕｌｄ）生物学系列研究之一，报告了１９８５年２月至１９８６年２月福宁湾尖刀蛏生殖腺周年发育和组织学观察的初步结果。性腺发育分４期：增殖期、成熟期、排放期、耗尽期。存在着雌雄同体和性变现象。雌雄性比和性变与贝龄有一定关系。     

The effect of PCBs on glycogen reserves in the eastern oyster Crassostrea virginica

Recent declines in Chesapeake Bay oyster populations have been attributed to disease, and reduced water quality from pollution. The stress associated with pollutant exposure may reduce energy available for growth and reproduction. Polychlorinated biphenyls (PCBs) are lipophilic contaminants that may potentially affect mobilization of lipid reserves, increasing reliance on glycogen stores, which could otherwise be utilized to supply energy for gametogenesis. Thus, PCBs may indirectly affect glycogen stores in oysters in a deleterious manner. To test for this effect, reproductively inactive oysters were exposed to PCBs by feeding individuals 0.7 g of algal paste containing 0, 0.35, or 3.5 μg PCBs daily for 8 weeks. Additionally, a group of oysters was exposed to PCBs (0, 0.35, and 3.5 μg) plus 0.3 g of non-toxic artificial sediment to examine interactive effects of sediment particles and PCBs. Adductor muscle, mantle, and gonadal tissues were analyzed for glycogen content. Results suggest that glycogen content is reduced in the adductor muscle with increasing PCB exposure, but there are no effects of PCBs in the mantle and gonadal tissues.