发头裸腹溞休眠卵发育的温度因子分析

测定了不同温度下发头裸腹溞(Moina irrasa)体眠卵的孵化时间及孵化率;取最先孵出和过半数孵出的两组数据依莱奥姆积温法则求得种群休眠卵最低临界温度为12.00℃,最低有效积温为441.61℃·h;最低亚致死高温点(即最适温度)为35.16℃,以及最低死亡高温点39.44℃。种群中过半数的临界温度为12.88℃,过半数有效积温为557.10℃·h,过半数的亚致死高温点为35.56℃以及过半数死亡高温点为39.49℃。讨论了这些参数在枝角类集约化培养中休眠卵的有效保存与启用所具有的实践意义。     

紫红笛鲷繁殖特性及诱导产卵的初步研究

描述紫红笛鲷Lutjanusargentimaculatus繁殖特性及人工诱导产卵的试验结果。紫红笛鲷养殖群体具有不完全的先雄后雌的性转化现象。1、2龄鱼全部为雄鱼,性腺成熟系数(GSI)为2.07%—4.85%;3龄亲鱼80%为雄鱼,20%转化为雌雄同体;4龄亲鱼性别转化基本确定,多数亲鱼为纯粹具有生殖机能的雄鱼,而在雌雄同体的亲鱼性腺中具有明显雌性第一性征的雌鱼仅占30%左右;雌雄同体的亲鱼性腺GSI为4.12%—8.09%,其中的卵巢GSI小于2%,4龄雌鱼怀卵量约70—100万粒;紫红笛鲷卵母细胞属非同步性发育,一个生殖季节能多次产卵。试验结果表明:低剂量的LHRH A2(3μg·kg-1)多次注射能有效地促进性腺发育、逐步成熟,并最终产卵,但对卵径小于300μm的亲鱼卵巢没有明显的诱导效果。在5μgLHRH A2+1000I UHCG·kg-1或5μgLHRH A2+500IUHCG·kg-1两种不同剂量的混合激素作用下,亲鱼的性腺都能迅速发育成熟,并能在小型循环式产卵池中自然产卵和受精。在水温为26.0—29.5℃的产卵池中,激素效应时间为35—43h。LHRH A2和HCG混合激素对卵母细胞直径达到400μm以上的紫红笛鲷亲鱼具有良好的促熟和催产效果,催产率达100%。如何减轻亲鱼之间相互残杀是改善雄鱼生理状况、保证雄鱼质量和提高卵子受精率必需解决的重要问题。     

A Quantitative Assessment of the Reproductive System of the Mediterranean Cave-Dwelling Triplefin Blenny Tripterygion melanurus

Abstract. The breeding biology of the cave-dwelling Mediterranean triplefin blenny Tripterygion melanurus (Pisces, Blennioidei) was studied in the field. Two types of reproductive male were observed, territorial males and non-territorial males. Territorial males establish territories for mating, but not necessarily for feeding, in caves and crevices at depths between 0.5 and 33  m. Territories can be settled in clusters in a single cave. Non-territorial males occur in the vicinity of territories and attempt to parasitise matings of territorial males. Gravid females wait near territories where another female is spawning, rather than spawn with currently unmated territorial males. Waiting females intrude in matings and sometimes displace a spawning female. The frequency of mating of the territorial male, of sneaking and of female intrusions are higher in territories that border others than in isolated territories. Females may minimise predation risks both on themselves and on their eggs by spawning in clustered territories and by spawning with males that have more than one clutch of eggs. Territorial males must find a compromise between the benefits of attracting a female and the costs of parasitic spawning by sneaker males. The possibility that territorial males tolerate the proximity of other territorial males and accept a risk of cuckoldry is discussed. Parasitic spawning in T. melanurus is relatively rare and the gonadosomatic index in both non-territorial and territorial males is low, indicating that sperm competition is probably not intense.     

三丁基氧化锡(TBTO)对太平洋牡蛎性成熟的影响

利用流水饲养法研究了不同浓度的三丁基氧化锡 (0 .5 μg/ L和 1.0 μg/ L TBTO)对太平洋牡蛎卵巢中卵母细胞直径、RNA/ DNA比、蛋白质和卵黄蛋白含量的影响。卵母细胞径的增长在0 .5 μg/ L实验组受到阻碍 ,并随着 TBTO浓度的增大而更加明显。TBTO暴露组的 RNA/ DNA比在精巢中无明显变化 ,但在卵巢中显著低于对照组。 TBTO暴露组的卵巢中蛋白质和卵黄蛋白含量显示了与 RNA/ DNA比相同的变化趋势 ,表明 TBTO的积累阻碍卵黄蛋白的合成。TBTO暴露4 2 d采集的牡蛎样品中出现 3个雌雄同体 ,暗示 TBTO可能引起牡蛎发生性转变进而产生雌雄同体     

HIV感染地域类型探讨——以中国某地区为例

HIV感染途径不同，使HIV感染对一般人群的威胁产生差异，因而衡量HIV感染流行程度时必须考虑HIV感染途径。选择性传播感染率、静脉吸毒人群感染率和孕妇感染率3项指标来衡量HIV感染流行程度，结合HIV感染途径对一般人群的威胁程度差别，这3项指标对衡量HIV感染流行程度的作用为：孕妇感染率＞性传播感染率＞静脉吸毒人群感染率。综合3项指标的划分标准，从理论上把HIV感染流行程度划分为18个，并用此方法将中国某地区HIV感染流行程度划分出高流行地域、次高流行地域、中度流行地域和低流行地域4个HIV感染地域类型，最后探讨了这4个地域类型的特点和成因。     

沙柳有性繁殖与关键环境因素的关系研究

沙柳种子的萌发受到多个因素的综合作用。在沙土含水量较低时沙柳种子可以萌发,但沙土含水量低于2%时不能萌发;干旱胁迫使沙柳实生苗发芽率降低;盐分可明显抑制沙柳种子萌发,同时抑制沙柳实生苗的茎生长;沙柳种子适宜的覆沙厚度是1.0～4.0 mm,当覆沙达到7 mm时种子出苗受到抑制;沙柳最适宜的发芽温度是25 ℃,当温度升到40 ℃时发芽率明显下降,而当降到10 ℃时种子发芽率也明显下降,达到5 ℃时沙柳种子尽管能发芽,但无茎生长。