【作者】 冉维亮；

【导师】 李广丽； 朱春华；

【作者基本信息】 广东海洋大学 ， 海洋生物学， 2010， 硕士

【摘要】 甲壳动物的性别分化由基因决定,并易受环境因子如温度、光照周期和寄生等影响。在一些经济甲壳动物中,特别是虾类,雌雄之间的个体大小差异显著,水产养殖中如若利用好这些雌性或雄性特征的优势,将能大大提高养殖效益。凡纳滨对虾的雌虾大于雄虾,因此,若对其进行雌性化诱导,可大幅度增加产量,提高经济效益。本实验通过外部形态观察和组织学连续切片,研究了不同温度、光照、盐度和壬基酚浓度对凡纳滨对虾性别分化的影响。主要研究结果如下:1、温度对凡纳滨对虾性别分化的影响研究了不同温度(25±1℃、29±1℃和33±1℃)对凡纳滨对虾生长早期性别分化的影响,并统计凡纳滨对虾的雌性率。结果表明:温度对凡纳滨对虾的雌性率没有显著影响(P﹥0.05),但显著影响了凡纳滨对虾的生长、性别分化时间及存活率;在29±1℃和33±1℃孵育条件下,凡纳滨对虾外部形态和性腺的分化时间早于25±1℃组,且平均体长也大于25±1℃组;在29±1℃孵育条件下,凡纳滨对虾存活率显著高于其他温度组,为31.4±3.1%。2、光照对凡纳滨对虾性别分化的影响研究了不同光照周期(6L:18D,12L:12D,18L:6D和24L:0D)和不同光照强度(800lx,3000lx和5000lx)对凡纳滨对虾生长早期性别分化的影响。结果表明:随光照时间的增长(从6L:18D到18L:6D),凡纳滨对虾的雌性率逐渐增大,18L:6D条件下雌性率达到57.5±1.4%;光照强度3000lx实验组凡纳滨对虾的雌性率高于800lx和5000lx组,但光照周期和光照强度的变化对凡纳滨对虾的雌性率没有显著性影响(P﹥0.05)。光照周期18L:6D和光照强度800lx条件下,凡纳滨对虾外部形态和性腺的分化最早,并且平均体长最大。凡纳滨对虾的存活率在光照周期24L:0D下最高(28.5±4.9%),显著高于6L:18D(P﹤0.05),但光照强度对凡纳滨对虾的存活率没有显著性影响(P﹥0.05)。3、盐度对凡纳滨对虾性别分化的影响研究了不同盐度(10,20,30和40)对凡纳滨对虾生长早期性别分化的影响。结果表明:盐度40条件下,凡纳滨对虾的雌性率最高(58.2±7.7%),且与10和20盐度组的雌性率之间存在显著性差异(P﹤0.05),30盐度组与其他三组之间没有显著性差异(P﹥0.05)。在盐度20～40范围内,随盐度的增高,凡纳滨对虾的雌性率逐渐增大,而存活率逐渐减小。10盐度组凡纳滨对虾的存活率最小,显著小于20和30盐度组(P﹤0.05),并且外部形态和性腺的分化迟于其他盐度组。4、壬基酚对凡纳滨对虾性别分化的影响研究了环境雌激素化合物壬基酚(4-nonylphenol,NP)对凡纳滨对虾生长早期性别分化的影响,将仔虾暴露于三个质量浓度(40、80、120μg/L)的NP中,并设空白对照组。结果显示:120μg/L NP处理组的凡纳滨对虾雌雄性比达到1.24:1,显著高于对照组(雌:雄=1:1.01)和80μg/L NP处理组。80μg/L和120μg/L NP处理组凡纳滨对虾的外部形态和性腺的分化早于对照组和40μg/L NP处理组。对照组与三个NP处理组的存活率之间没有显著性差异(P﹥0.05)。更多还原

【Abstract】 Sex differentiation on crustacean was determined by genes, however, it was easily affected by some environmental factors, such as temperature, photoperiod and parasite, etc. There exists obviously different body size between male and female in many economical crustaceans, especially in shrimp. If those sexy superior characteristics can be applied well in aquaculture, the breed benefit would be improved greatly. Body size of female Litopenaeus vannamei is larger than that of fale. Hence, if a good work can be done in feminizating of L. vannamei, the shrimp production and the economic benefit would be increased drastically. Effects of temperature, light, salinity and nonylphenol on sex differentiation were studied by morphologic observation and continuous histological sections on juvenile L. vannamei at its early stage of growth. The primary results of these studies are listed below:1. Effects of temperature on the sex differentiation on L. vannamei:Effects of different temperatures (25±1℃, 29±1℃and 33±1℃) on sex differentiation were studied at the early stage of growth on L. vannamei. The female rate was calculated following the experiment. The results showed that temperature obviously influenced the growth, sex differentiation starting time and survival rate of L. vannamei, but there were no significantly difference of female rate among the shrimps under the three temperature treatments (P﹥0.05). Sex differentiating time of both gonad and external morphology on L. vannamei at 29±1℃and 33±1℃groups were earlier than that at the 25±1℃group, so were the mean body-length. What’s more, the survival rate at 29±1℃(31.4±3.1%) was significantly higher than that at other groups.2. Effects of light on the sex differentiation on L. vannamei:Effects of different photoperiods (6L:18D, 12L:12D, 18L:6D and 24L:0D) and different light intensities (800lx, 3000lx and 5000lx) on the sex differentiation were studied at the early stage of growth on L. vannamei. The female rate generally raised with the illumination time from 6L:18D to 18L:6D, and the highest female rate (57.5±1.4%) existed at the 18L:6D group. The female rate at the 800lx group was higher than that at the other groups. However, it was not affected significantly by the changes of photoperiod and light intensity on L. vannamei (P > 0.05). The earliest sex differentiations time of both external morphology and gonad, as well as the largest mean length was found at the 18L:6D and 800lx group. The highest survival rate (28.5±4.9%) was found at the 24L:0D group, which was significantly higher than that at the 6L:18D group (P﹤0.05). However, no significant difference (P﹥0.05) in survival rate was found among the light intensity groups.3. Effects of salinity on the sex differentiation on L. vannamei:Effects of different salinity levels (10, 20, 30 and 40) on the sex differentiation were examined at the early stage of growth on L. vannamei. The results showed that female rate (58.2±7.7%) at the salinity 40 group was significantly higher than that both at the 10 and 20 salinity groups (P﹤0.05), however, no significant difference in female rate was observed between the salinity 30 group and the other three groups (P﹥0.05). The female rate increased and the survival rate decreased with the increasing salinity from 20 to 40. The lowest survival rate was found in salinity 10 group, which was significantly lower (P﹤0.05) than that at salinity 20 and 30 groups. Moreover, the sex differentiations of external morphology and gonad at salinity 10 were later than that at the other three salinity groups.4. Effects of nonylphenol on the sex differentiation on L. vannamei:Effects of environmental estrogen compound—4-nonylphenol (NP, 0μg/L, 40μg/L, 80μg/L and 120μg/L) on the sex differentiation were examined at the early stage of growth on L. vannamei. The results showed that the sex ratio (female: male) was up to 1.24:1 at the 120μg/L NP group, which was significantly higher than that both at the control (1:1.01) and the 80μg/L NP group (P﹤0.05). The sex differentiations time of both external morphology and gonad at the 80μg/L and 120μg/L NP group were earlier than that at the control and the 40μg/L NP group. There were no significant differences (P﹥0.05) in survival rate between the control and the three NP groups.更多还原