赤霉素诱导甘蔗节间伸长与内源激素变化的关系

探讨外源赤霉素对甘蔗节问伸长的效果及其与茎尖内源激素的变化关系.试验以新台糖22号为材料,在伸长初期以200 mg/L浓度的赤霉素进行叶面喷施,对照喷清水.结果表明,赤霉素处理的株高在各个时期显著高于对照,而且在处理后7,14和28 d分别比对照提高了17.32%、14.50%和8.35%.赤霉素处理引起植株表现的高度优势一直保持到后期,节间伸长效果主要集中在中部.赤霉素处理的CA,含量显著高于对照:ABA含量则相反,赤霉素处理的均显著低于对照.赤霉素处理的乙烯释放量稍低于对照,IAA含量从第7 d开始稍高于对照的;赤霉素处理对ZR含量的影响不明显.赤霉素处理的ABA/LAA的比值显著下降,ZMAA和EH.IAA的比值也有一定程度的下降,而提高了GA_3/IAA的比值.这说明外源赤霉素促进甘蔗节间的伸长可能主要通过调节ABA和赤霉素含量,其次是乙烯释放量和生长素含量,最终达到调节节间伸长效果.     

马铃薯试管薯诱导影响因素分析

以马铃薯栽培品种‘Favorita’脱毒试管苗为材料,研究了离体条件下外源激素、活性炭以及光照对试管薯形成和发育的影响。结果表明:加入一定浓度的外源激素,有利于提高‘Favorita’试管薯的产量和质量,其诱导效应依次为矮壮素(CCC)>多效唑(PP333)>CCC+6-苄氨基嘌呤(6-BA)>丁酰胺(B9)>6-BA>无激素;活性炭能够明显提高试管薯前期的形成和发育;8 h/d散射光照比全黑暗试管薯重量和大薯率都有提高;全黑暗使试管薯发生提前,结薯集中,但不利于试管薯的增重。     

鸭绿沙塘鳢仔鱼、稚鱼和幼鱼的形态观察

参照国内外对硬骨鱼类胚后发育期的分期标准,描述了鸭绿沙塘鳢仔鱼、稚鱼和幼鱼的形态特征,记录了各个发育时期的全长和体重等增长情况,讨论了鸭绿沙塘鳢仔鱼、稚鱼和幼鱼发育的生态适应性。     

Effects of 3,5,3′-triiodo-L-thyronine (T3) and 6-n-propyl-2-thiouracil (PTU) on growth of GH-transgenic coho salmon, Oncorhynchus kitsutch

GH-transgeniccoho salmon (Oncorhynchus kitsutch) juveniles were fed diets containing 3,5,3-triiodo-L-thyronine (T₃; 30 ng/g fish) or 6-n-propyl-2-thiouracil (PTU; 20 ug/g fish), to assess the effect of these drugs on the physiology, growthand survival in comparison with untreated transgenicand non-transgenic salmon. After 84 days, food intake, feed efficiency, survival, growth, hepato-somatic index (HSI), viscera-somatic index (VSI), plasma L-thyroxine (T₄), T₃and growth hormone (GH) levels,and cranial morphological abnormalities were determined. Growth of transgenic salmon was significantly faster than the nontransgenic salmon,and was increased by exogenous T₃and reduced by PTU. Food intake of transgenic salmon was higher than that of the nontransgenic group, but was reduced by exogenous PTU administration. Food conversion efficiency of transgenic salmon was lower than that of nontransgenic salmon,and also was increased by T₃ but reduced by PTU in the transgenic fish. The survival rate in all transgenic groups was significantly higher than that of nontransgenic,and transgenic T₃and PTU treatment groups showed higher survivals than the transgenic-control group. The HSIand VSI of the transgenic fish were higher than the nontransgenic fish;and both parameters in the transgenic salmon were increased by PTU, but reduced by T₃. The plasma T₄ level in transgenic salmon was approximately 1.5-fold higher relative to the nontransgenic fish, whereas no difference was observed among the transgenic groups. Plasma T₃ levels in transgenic salmon were also approximately 2-fold higher relative to the nontransgenic fish. However, the plasma T₃ level in transgenic animals was increased by exogenous T₃ administration, but was reduced by exogenous PTU to that observed in nontransgenic salmon. The plasma GH level of transgenic fish was higher than that of the nontransgenic salmon,and the level was increased by the exogenous T₃, whereas exogenous PTU did not reduce significantly GH levels in transgenic salmon. Transgenic fish also displayed cranium, jawand opercular abnormalities typical of the effects of this gene construct incoho salmon, indicating that some imbalance in growth processes has been induced. However, these abnormalities (especially cranial disruptions) were diminished by administration of exogenous PTU. In conclusion, exogenous T₃and PTU treatments can induce hyperthyroidismand hypothyroidism, respectively,and have inverse effects on growthand skeletal abnormalities of transgenic salmon constitutively expressing GH.     

Changes in plasma prolactin and growth hormone concentrations during freshwater adaptation of juvenile chum salmon (Oncorhynchus keta) reared in seawater for a prolonged period

Freshwater adaptability of chum salmon was examined in juvenile fish reared in seawater for 4 months. The fish, weighing about 40g, were transferred directly to fresh water in October, when their cohorts are migrating in the North Pacific Ocean. Plasma sodium concentration decreased from 167 mM in seawater to about 130 mM during the first 24h, and increased gradually during 2–7 days after the transfer. No immunoreactive prolactin (PRL) was detected in the plasma of the seawater-adapted fish nor during the first 24h in fresh water. Significant levels of PRL were detected after 2–3 days. The maximal level (2.6 ng/ml) was observed after 5 days and became undetectable again after 7 days; no significant correlation was seen between the changes in plasma sodium and PRL levels during the transfer. Plasma growth hormone levels were relatively constant, except for a significant decrease 12h after the transfer. Although plasma thyroxine levels were highly variable during the experiment, a significant decrease and an increase were observed 12h and 5 days after the transfer, respectively. The present study indicates that juvenile chum salmon retain hyperosmoregulatory ability even after prolonged rearing in seawater. Examination of turnover rates, rather than changes in plasma levels, seems to be essential to clarify the osmoregulatory roles of the hormones.     

温度对墨西哥湾扇贝幼虫和稚贝生长与存活的影响

为研究墨西哥湾扇贝人工育苗的适宜温度，2000年4月和2001年4月在浙江省玉环县抛西水产育苗场，通过设置不同温度梯度，研究了海水温度对墨西哥湾扇贝浮游幼虫和稚贝生长与存活的影响。结果表明：墨西哥湾扇贝浮游幼虫的适宜温度为20－33℃，最佳生长温度为25－30℃。稚贝的适宜温度为15－33℃，最适生长温度为25－30℃。     

大黄鱼仔、稚、幼鱼发育阶段的脂肪酸组成及其变化

研究了大黄鱼早期主要发育阶段（前仔鱼期、后仔鱼期、稚鱼、幼鱼）体内脂肪酸的组成及含量的变化规律,并重点比较了发病稚鱼与正常稚鱼的脂肪酸组成。用GC／MS法共检测到24种脂肪酸,且种类随发育而递增,其中饱和脂肪酸（SFA）12种,单不饱和脂肪酸（MUFA）6种,多不饱和脂肪酸（PUFA）6种。分析结果表明：大黄鱼鱼苗内源性营养阶段以饱和脂肪酸C14：0、C16：0及单不饱和脂肪酸C16：1、C18：1作为能量代谢的主要来源;必需脂肪酸C20：4（n-6）（AA）在鱼苗开口前就已存在,而DHA和EPA摄食后才被检测到,其含量受饵料种类的影响,DHA含量变化范围为7．26％～25．36％,EPA为3．41％～8．40％。与同期正常鱼苗相比,病鱼苗的主要脂肪酸DHA、EPA含量显著降低,DHA不足前者的1／3,而AA、C18：1、C18：2、C18：3含量和EPA／DHA的比值显著增加,分别是前者的1．5—3倍。导致稚鱼阶段“胀鳔病”发生的内在原因可能是DHA和EPA的缺乏以及AA偏高。研究结果为预防“胀鳔”鱼苗的发生提供了理论依据。     

Effect of dietary cholesterol levels on growth performance,body composition and gene expression of juvenile mud crab Scylla paramamosain

A 56‐day feeding trial was conducted to investigate the effect of dietary cholesterol (CHOL) levels on growth performance, body composition and gene expression of juvenile mud crab (Scylla paramamosain). Four isonitrogenous and isoenergetic diets were formulated with 0.4%, 0.8%, 1.2% and 1.6% CHOL supplemented, and the final dietary CHOL concentrations were 0.72%, 1.11%, 1.49% and 1.83% respectively. Each dietary treatment was performed with three replicates (28 crabs per replicate, initial body weight 0.04 g). At the termination of the experiment, although the survival had no statistic difference in all treatments, the mud crabs fed the lowest CHOL diet had the lowest survival rate. The weight gain (WG) of mud crab significantly increased with dietary CHOL level up to 1.11% and then significantly decreased with dietary CHOL level further increased. The total‐cholesterol (T‐CHOL) content in whole body had an increasing trend with the dietary CHOL level increased. Besides, dietary CHOL supplement generally increased the hepatic superoxide dismutase (SOD) activity, and the mud crabs fed diets CHOL1.11 and CHOL1.49 showed significantly higher value than those fed other diets. The hepatic aspartate aminotransferase (AST) activity decreased slightly with dietary CHOL level up to 1.11% and then significantly increased with CHOL level further increased. The mRNA expression of ecdysone receptor (EcR) gene in the eyestalk obviously increased with dietary CHOL level up to 1.11% and then significantly decreased with dietary CHOL further increased. These results suggested that about 1.11% dietary CHOL seem fulfil to maintain good growth performance and healthy condition for juvenile S. paramamosain.     

环境内分泌干扰物对硬骨鱼类甲状腺轴的干扰作用研究进展

甲状腺激素在鱼类的生长、发育、生殖等过程中均起着至关重要的作用,环境内分泌干扰物能够通过不同途径干扰硬骨鱼的甲状腺轴.本研究在介绍硬骨鱼下丘脑-垂体-甲状腺轴调控机制以及甲状腺激素在鱼体内动态变化过程的基础上,从甲状腺激素的合成、转运、转化、代谢以及清除等角度,总结了目前常用于指示鱼类甲状腺轴受干扰的指标,并从甲状腺轴生物标志物的研发、环境内分泌干扰物活体暴露时间和浓度选择、体外/体内相结合评价体系的建立以及微观水平指标与宏观水平指标相结合的角度,展望了该领域今后的研究重点和方向,以期为环境内分泌干扰物对鱼类甲状腺轴干扰作用研究提供更多的参考.     

鲮生长激素基因cDNA的分子克隆和序列分析

根据生长激素(growth hormone,GH)基因的保守性序列设计1对引物,利用RT—PCR技术从鲮(Cirrhina molitorella)脑垂体组织中克隆出经生长激素成熟肽cDNA片段,将纯化的DNA片段克隆到pUCm—T载体上。克隆的鲮GH cDNA开放阅读框全长567bp,编码由188氨基酸残基组成的生长激素成熟肽。序列分析结果表明,鲮GH成熟肽氨基酸序列与另2种鲮—印鲮(Cirrhina mrigal)和南亚野鲮(Labeo rohita)的成熟肽氨基酸序列同源性分别为87％和83％,与鲤的成熟肽氨基酸序列同源性为96％,并对9个科的17种鱼进行了分子系统进化树分析,结果与根据传统的形态学和生化特征分类进化地位基本一致。本研究所克隆的基因序列和推测的蛋白质序列已登录入GeoBank、EMBL和DDBJ基因库,序列号分别为AF458105和从AAL151107．1。