976 resultados para CHA-252


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Understanding the ontogenetic relationship between juvenile Steller sea lions (Eumetopias jubatus) and their foraging habitat is key to understanding their relationship to available prey and ultimately their survival. We summarize dive and movement data from 13 young-of-the-year (YOY) and 12 yearling Steller sea lions equipped with satellite dive recorders in the Gulf of Alaska and Aleutian Islands (n=18), and Washington (n=7) from 1994 to 2000. A total of 1413 d of transmission (x =56.5 d, range: 14.5–104.1 d) were received. We recorded 222,073 dives, which had a mean depth of 18.4 m (range of means: 5.8−67.9 m; SD=16.4). Alaska YOY dived for shorter periods and at shallower depths (mean depth=7.7 m, mean duration=0.8 min, mean maximum depth=25.7 m, and maximum depth=252 m) than Alaska yearlings (x =16.6 m, 0=1.1 min, x = 63.4 m, 288 m), whereas Washington yearlings dived the longest and deepest (mean depth=39.4 m, mean duration=1.8 min, mean maximum depth=144.5 m, and maximum depth=328 m). Mean distance for 564 measured trips was 16.6 km; for sea lions ≤10 months of age, trip distance (7.0 km) was significantly less than for those >10 months of age (24.6 km). Mean trip duration for 10 of the 25 sea lions was 12.1 h; for sea lions ≤10 months of age, trip duration was 7.5 h and 18.1 h for those >10 months of age. We identified three movements types: long-range trips (>15 km and >20 h), short-range trips (<15 km and <20 h) during which the animals left and returned to the same site, and transits to other haul-out sites. Long-range trips started around 9 months of age and occurred most frequently around the assumed time of weaning, whereas short-range trips happened almost daily (0.9 trips/day, n=426 trips). Transits began as early as 7 months of age, occurred more often after 9 months of age, and ranged between 6.5 and 454 km. The change in dive characteristics coincided with the assumed onset of weaning. These yearling sea lion movement patterns and dive characteristics suggest that immature Steller sea lions are as capable of making the same types of movements as adults.

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羊草(Leymus chinensis(Trin.)Tzvel.或Aneurolepidium chinense Trin.),隶属禾本科(Gramineae),大麦族(Hordeae),小麦亚族(Triticieae),赖草属(Leymus),兼具重要的生态价值和经济价值。面向国家重大需求,本论文选择羊草作为主要研究对象,开展了两方面的研究工作,即我国羊草种质资源的遗传多样性评价和赖草属物种的系统发育分析。 羊草是一种多年生根茎型禾草,根据叶色可以划分为黄绿型和灰绿型两种生态型。其分布范围横穿亚欧草原的东部,包括朝鲜和蒙古的西部,以及西伯利亚的西北部,集中分布于我国的东北部。羊草是我国典型草原植物群落中的优势种。它可以在多种土壤和气候条件下正常生长,如松嫩平原、内蒙古草原和黄土高原。从另一个角度讲,不同类型的生境也造就了羊草丰富的遗传多样性。 自上世纪90年代中期开始,我们陆续从我国东北部6个省市收集了293份羊草种质,包括205份灰绿型羊草和88份黄绿型羊草。经过连续3年的观测记录,通过37个重要农艺性状,对293份羊草的遗传多样性进行了评估。依据10个质量性状和27个数量性状,统计了羊草不同性状和不同地域羊草的Shannon遗传多样性指数,同时还使用了主成分分析和通径分析做了相关统计。结果显示:(1)与黄绿型羊草相比,灰绿型羊草具有更高的遗传变异(P<0.05)。结合这两个趋异型羊草的分布范围,可以得出两种类型羊草之间存在稳定的遗传差异;(2)通径分析显示,羊草营养生长性状和遗传多样性两者的组合效应可以解释羊草生殖特性中20.6%的遗传变异;(3)在124-128ºE这一区域,羊草的遗传多样性指数最高(H=2.252),表明这一地区具有最丰富的羊草种质资源。 赖草属(Leymus Hochst.)是一个异源多倍体属,约有34个物种,该属未知基因组的起源一直争论不休。其倍性范围从四倍体(2n=4x=28)、八倍体(2n=8x=56)一直到十二倍体(2n=12x=84)。新麦草属(Psathyrostachys Nevski)只含有Ns一个基因组,约有9个物种。这两个属都是多年生牧草,具有抗旱、抗病和耐盐碱等生物学特性。 应用核糖体ITS(Internal Transcribed Spacer)序列和叶绿体trnL-F序列,我们对13个赖草属物种、小麦族18个属(40份二倍体材料)、以及Elymus californicus和Bromus catharticus,共计57份材料进行了系统发生分析。ITS序列分析表明,赖草属分别与新麦草属和小麦族中一个未知属在进化上具有紧密的关系。ITS谱系树表明赖草属内部存在大量的分化,以及赖草属物种具有多次起源的特征。trnL-F序列分析表明,赖草属物种的母本,部分来自Ns基因组,部分来自Xm基因组,这可能与赖草属物种的地理分布有关,分布于亚欧大陆的物种其母本是新麦草属,而分布于北美的大部分物种其母本是Xm基因组。trnL-F序列分析还表明,E. californicus和赖草属未知的基因组具有紧密的关系。以上研究结果表明:(1)从分子层面证明,赖草属的未知基因组并非来自薄冰草属,或是一个修正的新麦草基因组,其基因组组成应是NsNsXmXm;(2)赖草属物种的母本,部分来自Ns基因组,部分来自Xm基因组,这可能与赖草属物种的地理分布有关;(3)E. californicus的母本是Xm基因组,父本是Ns基因组,该物种应从披碱草属转移至赖草属。

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EXTRACT (SEE PDF FOR FULL ABSTRACT): The most important control on the annual cycle of temperature is insolation, with secondary influences from terms related to moisture, yet direct statistical analysis of the moisture-driven modulations (such as El Niño) of the response of temperature to insolation are not available. We have examined one aspect of the relationship between insolation and the instrumental record of maximum daily temperature - the lag between the two - at 252 stations in the western United States.

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An account is given of the different types of gears and craft used to catch the pelagic and demersal fish in the inshore and estuary waters of Karwar, India. The main types of craft used during the fishing season September-May are: rampani boats, yendi boats, out-rigger boats, plank-built and dug-out canoes; important gears include: rampani, yendi, shore-seines, gill nets, boat seines, drift nets and hook and lines. Mechanized fishing, introduced during the sixties and seventies, included trawling and purse-seining. The types of gears used by the traditional fishermen depend on local conditions, seasons and distance covered from the shore. The major share to the total landings of fish in Karwar coast is brought mainly by the mechanized craft.

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A winch suitable for lowering and hauling up of costly hydrographic apparatus like Bathy-thermograph, Reversible thermometers, Current flow meters etc., was designed, fabricated and tested at Off Shore Fishing Station, Cochin. The first model of this winch is in use on board the motor vessel Pratap, a Tuna Long linger.

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为了阐明蕨类植物铁芒萁(Dicranopteris dichotoma Bernh.)体内稀土元素的分布及其光合特性,采用电感耦合等离子质谱分析了中国江西省龙南县轻、重稀土矿区和非矿区铁芒萁植物体内的稀土元素含量,并采用透射电子显微镜对其叶片细胞内的稀土元素进行精确定位。还比较系统的研究了自然条件下的铁芒萁与高浓度稀土元素处理条件下的非稀土元素富集植物黄瓜(Cucumis sativus Linn)的光合特性。结果表明: 1、0.5 mmol•L-1 LaCl3处理黄瓜后,可以诱导激发能向PS II分配。1和2 mmol•L-1 LaCl3处理黄瓜后,对黄瓜幼苗抑制作用表现在对其生长率,光合放氧活性和叶绿体完整率的抑制。这是由于LaCl3对黄瓜细胞结构和叶绿体膜结构的破坏所致。其表现为对类囊体膜结构的破坏,而导致PS II光合活性下降,并最终抑制黄瓜生长。 2、铁芒萁可以富集稀土元素,轻、重稀土矿区铁芒萁植物稀土元素的分布规律为叶片>根>土壤>茎>叶柄,非矿区铁芒萁植物稀土元素的分布规律为叶片>根>茎>叶柄。稀土元素在铁芒萁体内的运输和迁移过程中,发生了明显的分异作用,茎、叶柄、叶片中的重稀土相对贫乏,叶片中可以富集高浓度的轻稀土元素。 3、稀土元素可以进入完整的铁芒萁表皮细胞和叶肉细胞中,但多以沉淀的形式聚集在一起。非矿区铁芒萁叶绿体中的稀土元素含量约占其叶片中含量的5%。轻稀土矿区铁芒萁叶绿体中的稀土元素含量约占其叶片中含量的10%。部分稀土元素定位于富含PS II的基粒片层上。 4、铁芒萁富集稀土元素受环境和遗传特性的双重影响,但主要由其自身的生理、生化特性决定。其富集稀土元素的机制是隔离稀土元素在细胞壁、液泡中和分泌结合物质使稀土元素成为沉淀沉积下来,从而避免对光合活性的破坏。 5、与非矿区铁芒萁相比,轻稀土矿区植物叶绿体膜的全链电子传递速率增加了34.9%,PS II的电子传递活性增高了252.9%,PS I的电子传递活性增加了16.8%。轻稀土矿区铁芒萁全链电子传递活性的增加主要来自PS II电子传递活性的大幅提高,这可能与其调节激发能更多向PS II分配,提高PS II反应中心色素蛋白复合体(67.0%)和捕光色素蛋白复合体的含量相关。 6、与非矿区铁芒萁相比,重稀土矿区植物叶绿体膜的全链电子传递速率增加了46.3%,PS II的电子传递活性增高了23.8%,PS I的电子传递活性增加了60.4%。重稀土矿区铁芒萁电子传递活性的提高主要来自PS I电子传递活性的大量增加,这可能与其PS I反应中心蛋白复合体含量的提高(60.0%)有关。 铁芒萁富集并吸收稀土元素主要是由自身的理化特性决定的。它能够将稀土元素以沉淀的形式固定在细胞内部,并通过改变生理代谢来避免高浓度稀土元素对其光合作用的影响。可以在治理稀土元素污染的环保工程中用作植物修复材料。

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DLC films with different thicknesses (from 100 nm to 1.9 μm) were deposited using sputtering of graphite target in pure argon atmosphere without substrate heating. Film microstructures (sp2/sp3 ratio) and mechanical properties (modulus, hardness, stress) were characterized as a function of film thickness. A thin layer of aluminum about 60 nm was deposited on the DLC film surface. Laser micromachining of Al/DLC layer was performed to form microcantilever structures, which were released using a reactive ion etching system with SF6 plasma. Due to the intrinsic stress in DLC films and bimorph Al/DLC structure, the microcantilevers bent up with different curvatures. For DLC film of 100 nm thick, the cantilever even formed microtubes. The relationship between the bimorph beam bending and DLC film properties (such as stress, modulus, etc.) were discussed in details. © 2005 Elsevier B.V. All rights reserved.

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Hybridization between yak Poephagus grunniens and taurine Bos taurus or indicine B. indicus cattle has been widely practiced throughout the yak geographical range, and gene flow is expected to have occurred between these species. To assess the impact of cattle admixture on domestic yak, we examined 1076 domestic yak from 29 populations collected in China, Bhutan, Nepal, India, Pakistan, Kyrgyzstan, Mongolia and Russia using mitochondrial DNA and 17 autosomal microsatellite loci. A cattle diagnostic marker-based analysis reveals cattle-specific mtDNA and/or autosomal microsatellite allele introgression in 127 yak individuals from 22 populations. The mean level of cattle admixture across the populations, calculated using allelic information at 17 autosomal microsatellite loci, remains relatively low (mY(cattle) = 2.66 +/- 0.53% and Q(cattle) = 0.69 +/- 2.58%), although it varies a lot across populations as well as among individuals within population. Although the level of cattle admixture shows a clear geographical structure, with higher levels of admixture in the Qinghai-Tibetan Plateau and Mongolian and Russian regions, and lower levels in the Himalayan and Pamir Plateau region, our results indicate that the level of cattle admixture is not significantly correlated with the altitude across geographical regions as well as within geographical region. Although yak-cattle hybridization is primarily driven to produce F-1 hybrids, our results show that the subsequent gene flow between yak and cattle took place and has affected contemporary genetic make-up of domestic yak. To protect yak genetic integrity, hybridization between yak and cattle should be tightly controlled.

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鱼类是脊椎动物中最原始而在种属数量又最占优势的一个类群. 其分布广泛, 起源复杂, 阐明其系统进化途径, 历来是令人感兴趣的课题. 随着分子生物学向经典分类学领域渗透, 现在已可以通过 DNA 序列的比较来探讨生物的系统发育. 对于鱼类, 已有不少学者作了尝试. 由于受技术的制约, 用以研究的材料, 常常都要求新鲜. 但由于自然环境的变迁和人类的过度捕捞, 许多在系统进化研究中有代表意义的物种, 已非常稀少, 甚至濒临灭绝, 这给获取新鲜标本, 造成困难, 而许多标本馆, 由于多年的积累, 收藏的标本较齐全, 且绝大多数保存于4%-10%的福尔马林中。