Steroidogenesis in rainbow trout (Salmo gairdneri) at various preovulatory stages: changes in plasma hormone levels andin vivo andin vitro responses of the ovary to salmon gonadotropin

In order to specify the timing of some changes in ovarian steroid production during the transition from vitellogenesis to ovulation, plasma hormones levels andin vivo andin vitro responses of the ovary to salmon gonadotropin (s-GtH) or dibutyryl-cyclic adenosine mono-phosphate (db-cAMP) were recorded in relationship with the state of germinal vesicle migration in the oocyte.In vivo, a small, but significant, increase of plasma 17-hydroxy-20-dihydroprogesterone (17, 20-OH-P) level was detected earlier (at the subperipheral germinal vesicle stage) than the increase of GtH level (detectable at the peripheral germinal vesicle stage) and the decline of oestradiol-17 (E2–17) (also detectable at the peripheral germinal vesicle stage). Negative correlations were established between E2–17 levels and GtH (=–0.53) or 17,20-OH-P (=–0,43) levels while a positive correlation occurred between 17,20-OH-P and GtH levels (=+0,54).In vivo no action of GtH on the decline of E2–17 levels was detected GtH did not stimulate 17,20-OH-P production, within 72h, in females at the end of vitellogenesis stage. It had significant effect in females at other stages closer to ovulation, but the pattern of responses changed according to the stage.In vitro db-cAMP like GtH was able to stimulate 17,20-OH-P output from ovarian follicles. The greatest response was observed at the later stage. (GVBD). Testosterone output was also increased by GtH, but the lowest response was observed at the later stage (GVBD). Androstenedione output was lower than testosterone output.In vitro, a small but significant decline of E2–17 output was induced by GtH. We conclude that substantial changes occur during the very last stages prior to ovulation, both in the steroidogenic potential of the ovary and in the ovarian sensitivity to GtH. 20-oxydoreductase is probably progressively induced during GV migration when GtH basal levels are increasing but still relatively low. Without minimizing the role of discrete pulses of GtH on this induction, we could expect synergic actions of other hormones. Thus a high testosterone/oestradiol ratio in the follicle environment favours 17,20-OH-P secretion.     

乙烯利处理对促进金柑果实成熟的影响

在金柑果实着色初期喷施不同浓度的乙烯利处理,结果表明,40%乙烯利水剂200-400 mg.L-1处理均能促进金柑果实脱绿转色,但对果实风味及可溶性固形物、可滴定酸、还原糖、VC含量等指标没有显著改善作用;喷施≥600 mg.L-1乙烯利则出现严重落叶、落果。生产中可在果实着色初期以200-400 mg.L-1喷施,用于改善外观品质。     

淡水石斑鱼人工繁殖技术研究

对淡水石斑鱼的繁殖频率与水温、激素催熟的相关关系进行了研究,结果显示：淡水石斑鱼的繁殖频率随水温的升高而加快;注射LHRH—A2,可加快繁殖频率,注射剂量为0．8-1．0μg/kg(♀体重)时,有利于提高孵化率。此外,对亲鱼年龄与受精卵孵化率的关系及不同批次苗种生长的研究结果显示,2—4龄亲鱼产的卵,其孵化率在60％-70％;而在26—28℃情况下,不同批次苗种间的生长差异不大;在自然水温条件下,不同批次苗种间的生长存在差异。     

用代血清培养牛卵母细胞、早期胚胎和胚胎冷冻的研究

研究中用0％、0.25％、1％、2％代血清ultroser G和0.5％、1％、2％的代血清ultroser HY(以下称G和HY)。在体外成熟培养(IVM)、体外受精(IVF)、体外培养(IVC)和胚胎冷冻的各阶段中,分别代替10％的发情牛血清(OCS)、牛血清白蛋白(BSA)和15％的胎犊血清(FCS)。结果表明:(1)各组平均成熟率为98.9％±1.35,与对照组(10％OCS)无差异(P>0.05)。(2)体外受精时用修正的泰洛氏(Tyrod’s)溶液中分别加入不同浓度G和HY,各组的分裂率均低于对照组(P<0.01)。(3)受精后的2～8分裂球发育成囊胚,除0％和2％G组与10％OCS组有差异外(P<0.05),其余组无差异。(4)用含代血清培养液培养出7～8日龄的1～2级囊胚分别置于含3％HY、3％G和对照组(15％FCS)的冷冻液中(PBS),冷冻72h时后解冻培养的孵化率为76.6％、62％、77.3％和76.7％,除3％G组显著低于对照组(P<0.05),其余组无差异。     

牛卵母细胞体外培养成熟前后及体外受精卵SDH的电镜细胞化学研究

本文用Kerple-Fronius和Hajos的电镜细胞化学方法,对牛卵巢2-5mm卵泡中的卵母细胞及体外培养成熟卵和体外受精卵,进行了琥珀酸酶(SDH)定位及活性变化的研究.观察结果培养前的卵母细胞酶活性较明显,主要定位于线粒体膜上,内脊上也有少量的定位.体外培养成熟卵线粒体上的酶活性明显减弱.而体外受精卵在线粒体的膜及内脊上都有很强的酶活性定位.结果表明,牛卵母细胞的SDH活性随卵母细胞的成熟过程减弱,随受精过程增强. 本文还从超微结构角度上,对酶活性变化的原因进行了讨论     

Effect of Cryopreservation on the Expression of Tetraspanin CD9 in Sheep Oocytes

The experiment was aimed to explore the expression of CD9 in the follicles at different developmental stages, and investigate the effect of in vitro maturation and cryopreservation on CD9. The expression of CD9 protein in the follicle was detected by immunohistochemistry technique, the expression of CD9 mRNA was detected by Real-time quantitative PCR, CD9 protein was detected by Western blotting. The results showed that the CD9 fluorescence signal was detected by immunohistochemistry technique, and the fluorescence signal gradually increased with the maturation of the follicle, and fluorescence signal was the strongest in mature follicle;Real-time quantitative PCR showed that the expression of CD9 mRNA in fresh MⅡ oocytes was significantly increase (P<0.05), and was the least in frozen GV oocytes;The result of Western blotting indicated that CD9 protein was the most in fresh MⅡ oocytes and the expression of frozen GV oocytes was the least, consistent with the results of Real-time quantitative PCR. Cryopreservation of oocytes was more extensive than embryo cryopreservation. Tetraspanins CD9 played a very important role in sperm egg fusion. The above experimental results showed that the cryopreservation made damage to oocytes, decrease content of tetraspanins CD9 protein, and CD9 injury was one of the important reasons for the decline of fertilization rate.     

油茶果实成熟过程中内源激素和矿质元素含量的变化特征

为了探明油茶果实发育成熟过程中内源激素和主要矿质元素的变化特征,以我国南方广泛栽培的普通油茶良种‘长林4号’为试材,对其果实发育后期成熟过程中内源激素ABA、IAA、GA3、ZR和矿质元素氮、磷、钾、锰含量进行了测定,明确其变化规律,并探讨其与油茶果实发育和种子油脂积累的相关性。结果表明:油茶果实发育后期果实质量的增长呈现‘S’型曲线,种子油脂的积累进程发生在果实迅速膨大生长之后。油茶果实中ABA和IAA含量较高,ZR和GA3的含量较低。盛花后255 d 之前,种子中的内源激素ABA、IAA和GA较高,随着果实的发育成熟,果皮中内源激素ABA、IAA和GA的含量则明显高于种子,而且其变化特征与果实的生长发育动态相吻合,油茶发育后期果实的膨大生长与果皮内源激素IAA、GA3和ZR的含量紧密相关。在油茶种子油脂积累之前(盛花后255 d),种子内源激素ABA含量出现高峰,ABA在油茶种子成熟和油脂积累过程中可能起到了重要的作用。此外,在油茶果实迅速膨大期,果皮中氮和磷元素的含量表现出上升趋势,种子中氮、磷、钾和锰元素的含量表现出迅速下降趋势,随着种仁含油率升高,果皮中氮、磷元素含量表现出下降趋势,钾和锰元素的含量升高,种子中钾和锰元素含量呈现出下降趋势,表明油茶果实发育后期成熟过程中,果皮和种子中矿质元素可能发生了相互转运。      

脱落酸、乙烯利对草莓后熟和衰老的影响

脱落酸加快了草莓的后熟和衰老;乙烯利对草莓的呼吸强度和营养成分影响很小,对纤维素酶的活性有一定的促进作用。随着草莓的后熟和衰老,果实脱落酸含量和乙烯生成迅速上升,表明抑制ABA 的合成和排除贮藏环境中的乙烯都能延缓草莓的后熟和衰老。     

Effect of rearing temperatures on the growth and maturation of Arctic charr (Salvelinus alpinus) during juvenile and on‐growing periods

The effect of rearing temperature on the growth and maturation of Arctic charr (Salvelinus alpinus) was investigated. Arctic charr juveniles were reared for 6 months (phase I, October–April, size range 20–500 g) at constant temperatures of 9, 12 and 15 °C and according to two temperature‐step groups (T_step) i.e. fish transferred from 15 to 12 °C or from 12 to 9 °C. All the previous treatments were then reared either at 7 °C or at 12 °C for an additional 4 months (phase II, size range 300–1000 g) and then slaughtered in August 2008. The overall growth rate was the highest at a constant temperature of 15 °C for the first 6 months of the trial, with the fish in this group being 44% and 78% heavier than the fish reared at a constant temperature of 12 or 9 °C respectively. Arctic charr showed a negative response in terms of the growth rate when transferred from higher to lower temperatures, especially for groups previously reared at 15 °C. There was a trend for higher gonadosomatic index values at the end of the experiment for groups of fish that were exposed to higher rearing temperatures during the juvenile phase i.e. 4.18% (±0.79) and 7.29% (±0.89), for the temperature groups of 12 and 15 °C, respectively, compared with 2.49% (±0.74) for the 9 °C group. Our results suggest that for the production of fish >1000 g, moderate or low temperatures (here 9 °C) should be applied during the juvenile phase in order to reduce the negative effects arising from maturation. Farmers with access to heat sources should accordingly choose more moderate rearing temperatures during the juvenile stage, especially if the fish is to be moved down in the temperature regime during the on‐growing period.     

柿(Diospyros kaki L.)果实发育及成熟过程中内源GAs活性和ABA含量的变化

利用生物学方法和气相色谱法分别对柿有代表性的早、中、晚熟品种果实中内源赤霉素类物质(GAs)活性及脱落酸(ABA)含量的变化进行了测定。GAs 活性和 ABA 含量在幼果初期都很高,以后随果实的发育而迅速降低,在果实生长速度缓慢的第二期变化不大。但自果实进入成熟期开始,GAs 活性再次迅速降低,而 ABA 含量却呈增加趋势。发生这种变化的时期,与果实的成熟期一致。讨论了内源值物生长调节物质的平衡与果实成熟的关系。