Isolation and characterization of 15 polymorphic microsatellite DNA loci from Argyrosomus japonicus (mulloway), a new aquaculture species in Australia

Fifteen microsatellite loci were isolated for population genetic studies of mulloway (Argyrosomus japonicus), a commercial/recreational fish species in Southern Australia. A genomic library was screened randomly for di- tri- and tetranucleotide repeats. Fifteen microsatellite marker loci were developed that were highly polymorphic (allele number ranged from four to 18). Observed and expected heterozygosities ranged from 0.17 to 1 and from 0.27 to 0.91, respectively. These markers have proven useful for estimating genetic variation and for evaluating population structure across the species' natural distribution. They also provide powerful tools for optimizing hatchery practices to conserve genetic diversity.     

Flexibility of first brood production in a claustral ant, Camponotus japonicus (Hymenoptera: Formicidae)

The numbers of first-batch eggs and workers (minims) in a carpenter ant Camponotus japonicus are not fixed but are regulated in response to various internal and external factors of founding queens. The initial body weight of founding queens was positively correlated with the number of minims. The amount of queen weight loss during the founding period was highly correlated with the number of minims. The numbers of first-batch eggs and minims for artificially fed queens were significantly greater than those for control group queens and for unfed queens, respectively. The number of eggs laid by a queen increased when eggs deposited in the early stage of founding were removed. In contrast, artificial addition of alien eggs reduced the number of eggs laid by a queen. The adaptive implications of this flexibility in the production of the first-batch brood in C. japonicus are discussed. Received: December 18, 2000 / Accepted: March 19, 2001     

南海北部白姑鱼生长和死亡参数的估算

将南海北部白姑鱼分成南海北部大陆架和北部湾两个不同海域群体,根据20世纪60年代和90年代在南海北部底拖网渔业资源调查资料,利用ELEFAN技术估算了南海北部白姑鱼的生长和死亡参数.结果表明,北部湾和陆架区的生长参数L_∞、K、t₀分别为382mm、0.42、-0.16龄和315mm、0.35、-0.23龄.体重生长拐点年龄t_r分别为244和287龄;瞬时总死亡率(Z)、自然死亡率(MF)分别为3.55、0.93、2.62和3.12、0.85、2.27;当前开发率为074和073,资源处于过度利用状态.根据BevertonHolt动态综合模型,建议北部湾和陆架区白姑鱼的最适开捕年龄应大于190和195龄,相应的开捕体长大于2.11和168mm.     

A Patchy Growth via Successive and Simultaneous Cambia: Key to Success of the Most Widespread Mangrove Species Avicennia marina?

BACKGROUND AND AIMS: Secondary growth via successive cambia has been intriguing researchers for decades. Insight into the mechanism of growth layer formation is, however, limited to the cellular level. The present study aims to clarify secondary growth via successive cambia in the mangrove species Avicennia marina on a macroscopic level, addressing the formation of the growth layer network as a whole. In addition, previously suggested effects of salinity on growth layer formation were reconsidered. METHODS: A 1-year cambial marking experiment was performed on 80 trees from eight sites in two mangrove forests in Kenya. Environmental (soil water salinity and nutrients, soil texture, inundation frequency) and tree characteristics (diameter, height, leaf area index) were recorded for each site. Both groups of variables were analysed in relation to annual number of growth layers, annual radial increment and average growth layer width of stem discs. KEY RESULTS: Between trees of the same site, the number of growth layers formed during the 1-year study period varied from only part of a growth layer up to four growth layers, and was highly correlated to the corresponding radial increment (0-5 mm year(-1)), even along the different sides of asymmetric stem discs. The radial increment was unrelated to salinity, but the growth layer width decreased with increasing salinity and decreasing tree height. CONCLUSIONS: A patchy growth mechanism was proposed, with an optimal growth at distinct moments in time at different positions around the stem circumference. This strategy creates the opportunity to form several growth layers simultaneously, as observed in 14 % of the studied trees, which may optimize tree growth under favourable conditions. Strong evidence was provided for a mainly endogenous trigger controlling cambium differentiation, with an additional influence of current environmental conditions in a trade-off between hydraulic efficiency and mechanical stability.     

低盐度可诱导鲈鱼胞浆型PEPCK基因表达

磷酸烯醇式丙酮酸羧激酶(PEPCK)催化草酰乙酸生成磷酸烯醇式丙酮酸,是糖异生途径的第1个限速酶.本研究用SMARTRACE技术从鲈鱼肝脏中分离克隆了PEPCK基因的全长cDNA序列.该基因全长2215bp,包含1个123bp的5′非翻译区和217bp的3′非翻译区,开放阅读框为1875bp,编码1个由624个氨基酸组成的蛋白质,该蛋白理论分子量为69.1kD,等电点为5.87.氨基酸序列分析表明,与其它动物的胞浆型PEPCK相似性很高,与黑鲷为94.2%,与大西洋鲑为86.4%,与人为75.9%,而与该鱼线粒体型PEPCK氨基酸同源性只有70.6%.系统发育分析显示,该蛋白首先与其它动物的cPEPCK聚成一支,然后再与鱼类的mPEPCK成簇,认为该PEPCK属于胞浆型.同时用RT-PCR分析了PEPCK基因在10个组织中的表达,结果表明只有在肝脏、消化道和肾脏有较高的表达.将鲈鱼从盐度为25的海水转入盐度为12的海水48h后,肝脏和肾脏的PEPCK基因表达有增加.实验结果表明,本实验克隆的为鲈鱼胞浆型PEPCK,低盐度可诱导其表达.     

A simple model for the optimization of the extraction yield of antibiotics isolated from fermented broths by direct crystallization

This article is concerned with the development of a model to maximize the overall yield of isolation of antibiotics recovered from fermented broths by the so-called direct precipitation method. In this process, as in most antibiotics isolation processes, a second filtration of the semiexhaust mycellium from the first filtration, after slurrying it in water at the suitable pH, is required. The maximization of the overall yield of isolation implies the use of an optimal amount of water, measured as a volume to fermented broth mass ratio, which can be calculated by using the model derived here. The model also allows for the calculation of the partial and overall yields of the isolation process, and its validity is demonstrated by its ability to describe reasonably well the isolation data of two different tetracycline-fermented broths produced according to two different technologies.The application of the model requires only the knowledge of easily obtainable fermented broth parameters and is illustrated for two different types of tetracycline-fermented broths. Although the model had been derived for the optimization of the overall yield of isolation of antibiotics recovered by direct precipitation, it can easily be adapted to be used for the optimization of the overall yield of isolation of antibiotics recovered by other isolation processes. (c) 1993 John Wiley & Sons, Inc.     

利用黑色斑蚕作亲本、选育日系普斑限性品系

根据家蚕Bombyx moli斑纹互作原理,利用2032限性品种的雌,与自然突变体雄杂交。F2代出现分离,于是淘汰所有黑色斑蚕,只留下普斑蚕和素斑蚕,即得到新限性普斑系。新限性品系得到后,做连续3代的系统选育,其中F3代为蛾区混合育,F4～F5代采用单蛾育。蛾区混合育着重个体选择,单蛾育以蛾区选择为主,个体选择为辅。性状基本稳定后,即初步对其作主要经济性状的测定。结果显示:新限性品系在5龄经过、全龄经过上比两亲本略短。在全茧量、茧层量、茧层率几项指标上较两亲本为优,分别比两亲本平均值提高31%、38%、5%。     

电阻率成像法在树干水分吸收过程研究中的应用

将地球物理学中广泛运用的电阻率成像法成功地运用于树干内部截面电阻率分布特性的监测,利用电阻率平面分布图来分析树干内水分的空间分布和动态变化特征。结果表明：截面内树干水分的含量具有从核心部沿径向向外逐渐递增的趋势;位置较高的截面比较低的截面具有更多的水分含量,但充足的水分补给能打破这种水分分布的规律性,靠近补给源的截面含水率上升幅度最高;即使是在水分补给充足的情况下,树干内水分的吸收并不是面状饱和推进的过程,而是存在着优先纵向流动的生理机制;利用电阻率的变化,可以实现水分在截面上的优势流的定位。     

昆虫寄主标记信息素

综述了昆虫寄主标记信息素的研究进展。昆虫寄主标记信息素是指由昆虫产生的用来标记寄主上有同种个体存在的化学物质。昆虫寄主标记信息素的主要生态学功能是调节昆虫的产卵行为,通过阻止自身或同种其它个体对已标记寄主的产卵选择,或减少产卵量来减少后代之间对寄主资源的竞争。寄主标记信息素也会给释放着带来不利的影响,如信息盗用和盗寄生现象等。昆虫寄主标记信息素也调节昆虫近缘种之间对共同寄主资源的竞争。近缘种昆虫对相互寄主标记信息素识别能力的差异反映了不同昆虫对同一寄主资源竞争能力的强弱。寄主标记信息素产生和贮存的部位一般与外分泌腺、消化系统或生殖系统相联系,杜氏腺、毒腺、前胸腺、腹腺、下唇腺、后产卵管、卵巢、中肠和后肠等是产生或贮存寄主标记信息素的常见部位。产生的寄主标记信息素一般在成虫产卵时由产卵器、口器或排泄口释放到寄主体内或体表。卵寄生蜂的寄主标记信息素一般标记在寄主的体表,雌成蜂用触角检测;其它寄生蜂的寄主标记信息素常产在寄主体内,用产卵器检测;植食性昆虫的寄主标记信息素只产在寄主表面,用触角或产卵器检测。昆虫的产卵器、口器、触角或跗节上着生有感受寄主标记信息素的化感器,可以检测到标记在寄主体内或体表的寄主标记信息素。昆虫寄主标记信息素的完全定性涉及活性化合物的分离、鉴定、合成以及行为测定等,已有几种昆虫的寄主标记信息素成分得到了分离鉴定。     

Determination of tetracycline, chlortetracycline and oxytetracycline by flow injection with inhibitory chemiluminescence detection using copper(II) as a probe ion.

This paper reports an indirect flow-injection (FI) method for the determination of the tetracycline drugs (TCs), tetracycline (TC), chlortetracycline (CTC) and oxytetracycline (OTC), using copper(II) as a probe ion. The method was based on the inhibition caused by these TCs to the copper(II)-catalysed chemiluminescence (CL) reaction between luminol and H(2)O(2). The CL reaction was induced on-line and injection of the sample produced negative peaks as a result of the copper(II) complexation or displacement by the analytes. The height of the peaks was proportional to the drug concentration in the sample. The choice of the catalyst ion, the concentration of luminol, H(2)O(2) and copper(II) are discussed. The linear range was 3.6 x 10(-8)-1.0 x 10(-5), 1.1 x 10(-7)-1.0 x 10(-5) and 1.9 x 10(-7)-1.0 x 10(-5) mol/L for TC, CTC and OTC, respectively. The detection limit was 5.0 x 10(-9) mol/L for TC, 1.0 x 10(-8) mol/L for CTC and 2.0 x 10(-8) mol/L for OTC (3sigma), respectively. The method was applied to the determination of TCs in pharmaceutical preparations and human urine with recoveries in the range 95-105%.     

长江口两种重要石首鱼类的摄食习性

通过对2006年夏、秋季在长江口及其毗邻海域采集的575尾白姑鱼(Argyrosomus argentatus)和1089尾小黄鱼(Pseudosciaena polyactis)胃含物样品的分析,利用多元统计分析方法,研究了它们的摄食习性以及随栖息地、季节和体长的变化规律。结果表明:该水域的白姑鱼是底栖动物食性,小黄鱼是混合动物食性,甲壳类在它们食物中均占83%以上的比例,2种石首鱼类的食物重叠系数为0.55。由于摄食的优势饵料种类的差异,使这2种石首鱼类之间不存在严重的食物竞争。与20世纪80年代的研究结果相比,两种石首鱼类所摄食的鱼类的比例均有所下降。结果还表明:白姑鱼的摄食习性较为稳定,受栖息环境、季节以及体长变化的影响较小;而小黄鱼随栖息环境、季节以及体长的变化较大,且109mm是其发生食性转换的一个关键的临界体长。