Effect of hybridization on reproductive performance of Oreochromis karongae,Oreochromis shiranus and Oreochromis mossambicus

The study assessed the effect of hybridization on reproductive performance of Oreochromis karongae, Oreochromis shiranus and Oreochromis mossambicus for a period of 120 days. Number of eggs per batch, number of females spawned, relative fecundity, egg size, hatching period, hatchability and hatchling survival were assessed. The results revealed higher number of eggs per batch and relative fecundity in the crosses where O. shiranus and O. mossambicus were females than female O. karongae. The results also revealed that egg size, hatching period, hatchability and hatchling survival were species specific. Significant differences were noted for number of eggs and larvae produced by the three species (p < .05). Interspecific and pure crosses for the same female species did not differ significantly for the number of eggs per batch, relative fecundity, egg size, hatching period, hatchability and hatchling survival. However, number of female spawned was found to be higher in the interspecific crosses of female O. karongae than in pure cross of O. karongae. Findings from this study suggest that hybridization can be used to improve reproductive performance of O. karongae as the females spawned increased, and it is a value addition in aquaculture management of indigenous species.     

Potential fecundity of an introduced population, Keban Dam Lake, Elazı , Turkey, of freshwater crayfish, Astacus leptodactylus leptodactylus (Esch., 1852)

Potential fecundity of an introduced population, Keban Dam Lake, Elazı , Turkey, of freshwater crayfish, Astacus leptodactylus leptodactylus (Esch., 1852), was investigated in the present study. The results showed that there was not a linear relationship between female size and pleopodal egg number. The results also showed that although there is an increase in the mean pleopodal egg number with an increase in size (carapace length, CL), it is not the most important factor affecting potential fecundity in A. leptodactylus (slope=1.9294). Mean pleopodal egg number was 305.93 (S.E.=8.82) for the size range of 47–76 mm CL (N=96). The maximum pleopodal egg number was 588 for the crayfish in a 72-mm CL. The present study showed that Keban Dam Lake population of A. leptodactylus has more potential fecundity than the other populations in Turkey. The egg-bearing capacity of female A. leptodactylus caught from Keban Dam Lake could improve efficiency in controlled hatchery production of juveniles.     

管角螺受精过程的荧光显微观察及保育卵形成分析

为了研究管角螺受精卵在受精和早期卵裂过程中的核相变化以及保育卵的形成,实验通过Hoechst 33258染色、荧光显微观察方法,对管角螺受精和早期卵裂过程中核行为的细胞学变化进行了详细观察,并对其胚胎发育过程中的数量变化进行统计分析。结果显示,管角螺的成熟未受精卵呈卵圆形,平均卵径(0.33±0.03)mm,核相处于第一次成熟分裂中期,在水温为(26±2)°C条件下,1 h精子入卵,2~3 h受精卵先后排出第1、第2极体,完成第一次和第二次成熟分裂,6 h雌、雄性原核形成,靠近融合,第一次卵裂形成2细胞,12~24 h时2细胞继续分裂生成4细胞。研究表明,管角螺受精卵在成熟分裂和卵裂过程中表现出发育的不同步性,同个卵荚内多个发育阶段共存,受精率为43.14%,而受精卵正常发育概率仅5.70%。卵荚内多数卵子不受精或者受精卵停止发育,成为营养卵(保育卵),为正常可育卵消化利用,这两种来源的保育卵比率约为3∶2。管角螺胚胎发育过程中,1~6 d内胚胎数减少明显,担轮幼虫发育率为0.48%,之后数量稳定,直至稚螺出膜。     

SCP3作为栉孔扇贝初级精母细胞标记分子的研究

为检验SCP3在无脊椎动物中是否可以标记特定的生殖细胞,实验利用RACE技术克隆了栉孔扇贝SCP3(Cf-SCP3)的全长cDNA序列,结果显示,其长度为1 033 bp,开放阅读框为726 bp,编码241个氨基酸。推导的氨基酸序列中包含SCP3保守的Cor1结构域和卷曲螺旋结构域。制备了Cf-SCP3地高辛标记的RNA探针和Cf-SCP3重组蛋白的多克隆抗体,采用原位杂交和免疫组织化学技术检测其细胞学定位,结果显示Cf-SCP3转录本和Cf-SCP3蛋白均特异性地定位在栉孔扇贝的初级精母细胞和未受精卵中,在精巢的其他类型细胞和卵巢中均未见表达信号。研究表明,Cf-SCP3蛋白可能与脊椎动物的SCP3蛋白一样,作为联会复合体的组成成分参与栉孔扇贝的配子发生,同时可以作为一个栉孔扇贝初级精母细胞的分子标记应用到体外诱导生殖细胞分化的研究。     

黄颡鱼早期发育阶段受精卵和鱼体脂肪酸组成变化

研究了黄颡鱼受精卵孵化期间和仔鱼发育阶段脂肪含量和脂肪酸的组成变化规律.采用常规化学分析方法和气相色谱法对黄颡鱼从鱼卵受精开始至仔鱼孵化后未投饵的7 d内的脂肪含量和脂肪酸组成进行测定.结果表明,受精卵在整个孵化期间脂肪含量有下降趋势.受精卵中不饱和脂肪酸含量大于饱和脂肪酸含量.受精卵在整个孵化期间各种脂肪酸含量无明显变化.仔鱼孵化后,鱼体总脂肪含量急剧下降,总脂含量从0日龄的4.57%降低到7日龄的0.75%.仔鱼在饥饿期间鱼体脂肪酸组成发生明显变化,单不饱和脂肪酸含量下降最为明显,尤其是C18:1.仔鱼在饥饿期间,脂肪酸按n-9>n-6>n-3顺序被先后利用,黄颡鱼仔鱼发育阶段主要以单不饱和脂肪酸作为能量代谢基质,而C20:4n6(AA)和C22:6n3(DHA)优先于C20:5n3(EPA)被保存下来.     

Egg oxidation status,antioxidant enzyme activities,lipid classes,fatty acid composition profile and embryo survival rates during in vitro oocyte ageing in tench Tinca tinca (Linnaeus, 1758)

The effect of in vitro storage of oocytes on embryos survival rate, egg oxidation status, antioxidant enzyme activities, lipid classes and fatty acid composition profile was investigated in common tench Tinca tinca. In order to identify the role of oxidative stress in the progress of oocyte ageing the levels of thiobarbituric acid reactive substances (TBARS) and carbonyls as indicators of lipid and protein oxidation were measured and the activity of antioxidant enzymes were examined. Stripped ova from six females were stored in cell culture plates at 20°C for up to 10 hr post‐stripping (HPS). The stored ova were fertilized and the embryo survival rates were assessed. The results indicated that tench eggs could be successfully stored in vitro for 4 hr after stripping at 20°C. Superoxide dismutase enzyme activity increased at 6 HPS, whereas glutathione peroxidase and glutathione reductase activities decreased in oocytes during in vitro storage (p < .05) at 4 and 8 HPSs, respectively. The level of malondialdehyde did not show any significant changes during the progress of oocyte ageing. Carbonyls increased up to 2 HPS and thereafter decreased significantly. However, ova ageing did not affect the main lipid class composition and the fatty acid composition of the eggs. Lower quality eggs exhibited lower levels of cholesterol but higher levels of triacylglycerol.     

板栗贮藏保鲜方法的合理应用

对板栗贮藏保鲜方法的特点进行分析,并根据不同的贮藏保鲜目的要求和实际条件来合理应用。对于贮藏量大、贮存期长、保鲜质量要求高的单位,宜应用机械冷藏方法。对于缺乏冷藏设备条件的单位和广大农户,可应用常温贮藏法。     

一种无精蛋自动挑选系统设计

设计了孵化早期无精蛋自动挑选系统,结合各执行机构,对系统的电路及软件作了详细的研究。选取种蛋立位透光图像中的各部分的面积值作为无精蛋的识别特征。系统以TMS320DM642型DSP与EPM7128AETC型CPLD为控制核心,蛋盘设计为可自动切换的两种状态（孵化状态与检测状态）。种蛋的图像由CCD采集,由DSP经图像处理,神经网络识别后并由喷墨装置标记出无精蛋。     

石门柑橘产业发展探讨

石门是产橘大县,但一些因素制约了石门柑橘产业的发展,如柑橘特色不够鲜明、采后商品化处理不到位、小农户与大市场之间矛盾尖锐、鲜销与深加工结构失衡等。要加快石门柑橘产业发展必须要坚持鲜销与深加工两条腿走路,发展订单生产,充分发挥行业协会的作用,并围绕鲜销和加工的需要调整品种结构。     

鲜食玉米超早播种研究

选用糯玉米品种渝糯7号,研究在永州市气候条件下不同时期春播种植的鲜食玉米生产发育特性及产量和经济效益。结果表明：鲜食玉米超早播种的最佳时期为3月5日左右,该期内病虫害轻,无倒伏现象,可获得较高产量及效益。