985 resultados para 569
Resumo:
Gonadal morphology and reproductive biology of the Black Anglerfish (Lophius budegassa) were studied by examining 4410 specimens collected between June 2007 and December 2010 in the northwestern Mediterranean Sea. Ovaries and testes presented traits common among fishes of the order Lophiiformes. Spawning occurred between November and March. Size at first maturity (L50) was 33.4 cm in total length (TL) for males and 48.2 cm TL for females. Black Anglerfish is a total spawner with group-synchronous oocyte development and determinate fecundity. Fecundity values ranged from 87,569 to 398,986 oocytes, and mean potential fecundity was estimated at 78,929 (standard error of the mean [SE] 13,648) oocytes per kilogram of mature female. This study provides the first description of the presence of 2–3 eggs sharing the same chamber and a semicystic type of spermatogenesis for Black Anglerfish. This new information allows for a better understanding of Black Anglerfish reproduction—knowledge that will be useful for the assessment and management of this species.
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根癌农杆菌通过将一段含有“癌”基因的T-DNA导入植物基因组中,引起植物的肿瘤:冠瘿。根癌农杆菌的这种能力来源于Ti质粒(Tumor inducing plasmid)。遗传工程中,根癌农杆菌的这一特性被用来将连接入Ti质粒T-DNA区两个边界之间的外源基因转入植物基因组。随着植物分子生物学的发展,T-DNA转化的原理被进一步阐明,农杆菌介导的转基因技术也得到进一步优化,更适合遗传工程操作。特别是Ti质粒毒性区和T-DNA区的反式作用(即位于不同质粒的T-DNA和毒性区也能侵染植物)被发现以来,双元表达载体的构建使遗传工程操作大为简便。 常用的双元表达载体大小都在11kb以上,尽管远远小于几百kb的野生型Ti质粒,但在实际的体外操作中还是不够简便。常用的植物双元表达载体pBI121的基因序列被测定(Frisch et al.,1995),数据显示非T-DNA区一半以上的序列被发现和功能无关,这使双元载体的进一步缩小成为可能。本文即通过PCR方法克隆到pBI121非T-DNA区中载体复制、三亲杂交必需的片段,结合载体pART27中的T-DNA区(含有真核、原核表达活性的嵌合npt II基因)创造了小的合成型植物表达双元载体pSY1(小于7kb)。然后将pBI121上带有35S启动子和nos终止子的GUS基因克隆到pSY1的T-DNA区中,得到pSY2(约10kb)。进一步用pROK2上的35S启动子和nos终止子区替换pSY2上的GUS表达区,得到pSY3(约8kb)。通过三亲法将pSY2转入根癌农杆菌中,根癌农杆菌再通过叶盘法侵染烟草叶片,获得愈伤组织,愈伤组织进一步分化出小苗。GUS组织化学染色表明GUS基因在转基因的愈伤组织和小苗中均有表达,PCR检测也证明GUS基因被导入了植物基因组。pSY系列载体能成功的用于植物遗传转化。
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地上净初级生产力(ANPP)是陆地生态系统碳循环的重要组成部分,但由于估测ANPP的方法不同使得对ANPP的估测值存在很大的不确定性。本文采用3种方法(群落中所有种群当年最大地上生物量之和(ANPPC1)、当年群落最大地上生物量(ANPPC2)以及每年固定日期(8月30日)的地上生物量(ANPPC3))在种群、功能群和群落水平上分别对连续19年(1980~1998)的内蒙古羊草和大针茅草原生态系统功能(如ANPP、植物多样性和水分利用效率(WUE))的动态变化进行了比较分析,同时探讨了不同估测方法下气候和放牧对ANPP的影响,在此基础上利用DNDC模型进行了ANPP的模拟和敏感性分析研究,主要结果包括: 在羊草和大针茅草原群落中,不同主要植物种群或功能群多年平均地上最大生物量出现的时间不同,而同一植物种群或功能群的年地上最大生物量出现的时间存在年际间的变化。采用当年最大地上生物量和8月30日固定日期的地上生物量作为群落ANPP的这两种方法高估了建群种或禾草功能群在群落中的作用。 羊草草原群落多年平均ANPPC1、ANPPC2和 ANPPC3分别是257.5、190.1和166.0 g.m-2;相应的大针茅草原多年平均ANPPC1、ANPPC2和 ANPPC3分别是180.4、132.8和122.5 g.m-2。就群落生产力而言,后两种常用的方法二和方法三分别低估了草原群落ANPP 14.2%~40.0%和15.5~59.0%。本文研究表明尽管ANPPC1与ANPPC2和ANPPC3之间存在显著的差异,但二者之间存在极显著的相关性:羊草草原的ANPPC1= 59.587+1.061×ANPPC2(r2=0.865, p<0.001),ANPPC1= 92.329+1.017×ANPPC3(r2=0.569, p<0.001);大针茅草原的ANPPC1= 32.918+1.114×ANPPC2(r2=0.814, p<0.001),ANPPC1= 76.120+0.875×ANPPC3(r2=0.499, p=0.001)。 种群、功能群和群落地上净初级生产力与气候因子间的关系因不同的估测方法而异。羊草草原的建群种羊草种群仅ANPPS3与8月和11月份的平均温度间存在显著相关性,而大针茅草原群落的建群种大针茅种群的ANPPS1和ANPPS2与3月份平均最高气温间呈负相关关系。在羊草草原群落,杂类草功能群ANPPF1和ANPPF2与3月份气温呈负相关关系;而灌木半灌木功能群ANPPF1和ANPPF2与3月份降水呈负相关关系。在大针茅草原群落,禾草功能群ANPPF1与5月份最高平均气温呈显著负相关关系。羊草草原群落ANPPC1和ANPPC3分别与11月份最低温度和平均温度存在显著负相关关系;大针茅草原群落ANPPC1与2和6月份月降水量间相关性显著,ANPP2与5月和11月份月平均最低温度呈显著负相关关系,而4~9月份,1和4月份平均最低温度对群落ANPPC3起决定作用。 在羊草和大针茅草原群落,由方法一得到的群落水分利用效率、Shannon植物多样性指数和均匀度指数与方法二或方法三得到的相应的指数间存在显著的差异,方法二和方法三得到的值间差异不显著。群落地上净初级生产力与相应估测方法的植物Shannon多样性指数和均匀度指数之间相关性不显著。 放牧条件下羊草或大针茅草原群落中的建群种羊草和大针茅在群落中的相对地上生物量较围栏内的相应植物种群的降低,而糙隐子草种群在群落中的比例上升。不同的放牧管理条件下,群落中植物种群地上现存量的季节动态发生变化。群落的植物组成及植物种群地上生物量在群落中总生物量的比例发生了明显的变化。利用遥感来估测地上净初级生产力时,分别低估了羊草和大针茅草原ANPP 52%和27%。 DNDC模型可以很好地模拟内蒙古典型草原生态系统的地上生物量,通过敏感性分析表明降水是草原植物生长的主要限制因子,在降水量增加或降低至日降水的30%时,模拟的地上生物量显著地高于或低于实测地上生物量值。在多年平均降水量为347mm的情况下,随着土壤粘粒含量的增加,地上生物量逐渐降低,与北美草原一致。
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Partial sequences of cytochrome b (Cyt b) and 16S ribosomal RNA (16S rRNA) mitochondrial genes were used for species identification and estimating phylogenetic relationship among three commercially important Ompok species viz. O. Pabda, O. pabo and O. bimaculatus. The sequence analysis of Cyt b (1118bp) and 16S rRNA (569 & 570bp) genes revealed that O. pabda, O. pabo & 0. bimaculatus were genetically distinct species and they exhibited identical phylogenetic relationship. The present study discussed usefulness of mtDNA genes (Cyt b & 16S rRNA) in resolving taxonomic ambiguity and estimating phylogenetics relationship.
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Giant panda hair samples obtained by noninvasive methods served as a source of DNA for amplification of seven giant panda microsatellite loci utilizing the polymerase chain reaction. Thirteen giant pandas held in Chinese zoos were tested for identification of paternity. Some males listed as sires have been excluded as the biological father of captive-born giant pandas. Because of the death of some potential sires, paternity is still not assigned for some giant pandas, although there is a high likelihood that paternity assignment could be made if postmortem samples are available for genetic analysis. The DNA microsatellite variation assayed by the test we have developed provides a rapid, highly informative, and noninvasive method for paternity identification in giant pandas. (C) 1994 Wiley-Liss, Inc.
Resumo:
Ink-jet printing of nano-metallic colloidal fluids on to porous media such as coated papers has become a viable method to produce conductive tracks for low-cost, disposable printed electronic devices. However, the formation of well-defined and functional tracks on an absorbing surface is controlled by the drop imbibition dynamics in addition to the well-studied post-impact drop spreading behavior. This study represents the first investigation of the real-time imbibition of ink-jet deposited nano-Cu colloid drops on to coated paper substrates. In addition, the same ink was deposited on to a non-porous polymer surface as a control substrate. By using high-speed video imaging to capture the deposition of ink-jet drops, the time-scales of drop spreading and imbibition were quantified and compared with model predictions. The influences of the coating pore size on the bulk absorption rate and nano-Cu particle distribution have also been studied.