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排序方式: 共有230条查询结果,搜索用时 203 毫秒
111.
STEFAN SAFER KARIN TREMETSBERGER YAN‐PING GUO GUDRUN KOHL MARY R. SAMUEL TOD F. STUESSY HERMANN STUPPNER 《Botanical journal of the Linnean Society. Linnean Society of London》2011,165(4):364-377
The genus Leontopodium comprises 30–41 species. The centre of diversity is the Sino‐Himalayan region in south‐western China, where about 15 species occur. The two species native to Europe, L. alpinum (known as the common ‘Edelweiss’) and L. nivale, are part of the cultural heritage of the people living there. Despite its importance, very little is known about the systematics of the genus. Because recent molecular studies have shown that species within this genus are closely related and difficult to distinguish with rDNA and cpDNA data, we used AFLPs to obtain a more detailed understanding of the phylogeny of the genus. Our main aims were as follows: (1) to clarify species relationships within the genus; and (2) to reveal information about the biogeography of the genus. We used AFLPs with six primer combinations to investigate 216 individuals in 38 populations of 16 different species. With AFLPs, we were able to recognize 10 different groups, all of which had strong bootstrap support. These results were also congruent with the morphology‐based taxonomy of the genus. Most private and rare fragments were found in the Yunnan region (south‐western China) relative to Europe and Mongolia/central China, suggesting a long‐lasting in situ history of populations in the centre of diversity of the genus. Our results illustrate the utility of AFLPs to resolve phylogenetic relationships between these closely related species. © 2011 The Linnean Society of London, Botanical Journal of the Linnean Society, 2011, 165 , 364–377. 相似文献
112.
VIRGINIA E. VILLAFAÑE KUNSHAN GAO PING LI GANG LI E. WALTER HELBLING 《Freshwater Biology》2007,52(7):1260-1270
1. The importance of vertical mixing in modulating the impact of UVR on phytoplankton photosynthesis was assessed in a tropical, shallow lake in southern China from late winter to mid‐spring of 2005. 2. Daily cycles of fluorescence measurements (i.e. photosynthetic quantum yield, Y) were performed on both ‘static’ and in situ samples. Static samples were of surface water incubated at the surface of the lake under three radiation treatments – PAB (PAR + UVR, 280–700 nm), PA (PAR + UV‐A, 320–700 nm) and P (PAR, 400–700 nm). In situ samples were collected every hour at three different depths – 0, 0.5 and 1 m. 3. The general daily pattern was of a significant decrease in Y from early morning towards noon, with partial recovery in the afternoon. Samples incubated under static conditions always had lower Y than those under in situ conditions at the same time of the day. 4. Under stratified conditions, no overall impact of UVR impact could be detected in situ when compared with the static samples. Further rapid vertical mixing not only counteracted the impact of UVR but also stimulated photosynthetic efficiency. 5. Based on these measurements of fluorescence, the mixing speed of cells moving within the epilimnion was estimated to range between 0.53 and 6.5 cm min−1. 6. These data show that mixing is very important in modulating the photosynthetic response of phytoplankton exposed to natural radiation and, hence, strongly conditions the overall impact of UVR on aquatic ecosystems. 相似文献
113.
目的:探讨RIP3(受体相互作用蛋白-3)在淋巴瘤患者病理组织中是否表达及其亚细胞定位,并初步观察RIP3的表达是否与淋巴瘤病理恶性度相关。方法:(1)利用免疫组化技术检测48例淋巴瘤和非肿瘤侵润淋巴结病理组织中RIP3表达,并观察RIP3亚细胞定位。结果:(1)RIP3在淋巴瘤患者病理组织中均有表达,其亚细胞定位主要在细胞核,在细胞质中相对弱表达。(2)RIP3表达与淋巴瘤病理恶性度可能存在相关性。结论:RIP3在淋巴瘤患者病理组织中存在阳性表达,为研究RIP3是否与淋巴瘤的发病、临床表现和预后相关,提供了新的探索途径。 相似文献
114.
XIAO‐LEI HUANG JING‐GONG XIANG‐YU SHAN‐SHAN REN RUI‐LING ZHANG YA‐PING ZHANG GE‐XIA QIAO 《Zoological Journal of the Linnean Society》2012,165(1):73-87
The aphid subfamily Hormaphidinae is a good candidate for the study of the evolution of insect – plant relationships. Most hormaphidine species depend on woody primary host plants and woody or herbaceous secondary host plants, and represent high host specificity, especially to their primary hosts. No detailed molecular phylogeny of Hormaphidinae has been reported, and the taxonomic positions of some taxa in this group remain unclear. To reconstruct major phylogenetic relationships and to understand the evolution of host association patterns for major lineages, we present the first detailed molecular phylogeny of Hormaphidinae, as inferred from nuclear and mitochondrial DNA sequences, using maximum parsimony, maximum likelihood, and Bayesian methods. The monophyly of Hormaphidinae and its three traditional tribes was supported, and a sister relationship between Hormaphidini and Nipponaphidini was suggested. Most inner relationships within tribes were also supported, and some novel relationships were revealed. Two subtribes of Cerataphidini are proposed. Divergence times estimated using a Bayesian approach indicate that tribal diversifications occurred during the Late Cretaceous and were coincident with the appearance of their primary host plants. The current pattern of secondary host association for the three tribes may have evolved in different time ranges. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 165 , 73–87. 相似文献
115.
Abstract: Three‐dimensional fragments of palaeoscolecid cuticle have been recovered from the Furongian (upper Cambrian) of Hunan, South China. Extraordinary preservation of the fossils shows exquisite surface details indicating a three‐layered structure of the cuticle. One new genus and two new species Dispinoscolex decorus gen. et sp. nov. and Schistoscolex hunanensis sp. nov. are described. The co‐occurrence of these palaeoscolecid remains with those of Markuelia hunanensis allowed us to test the hypothesis that Markuelia, known hitherto only from embryonic remains, is an embryonic palaeoscolecid. The comparative anatomy of Markuelia and the co‐occurring palaeoscolecids shows a number of distinctions, particularly in the structure of the tail; all similarities are scalidophoran or introvertan (cycloneuralian) symplesiomorphies. The available evidence does not support the interpretation of Markuelia as an embryonic palaeoscolecid. 相似文献
116.
白蚁是一类受到世界广泛关注的重要社会性昆虫,对人类生活、经济以及生态环境等有很大的影响,特别是乳白蚁属Coptotermes众多种类危害尤为严重。乳白蚁常随木质包装或原木远距离传播异地建群,其为害隐蔽、潜伏期长,一旦爆发则为害严重且难防治,因其种类多、形态趋同,同一巢群中有龄期不一的虫态和多种生物型,可用分类特征少,造成形态分类困难、人为分类现象普遍。近年来分子生物学技术的日益发展,使得白蚁的分类鉴定更加快速、灵敏和可靠,系统发育分析研究更为深入全面,遗传进化方面取得大量研究成果。本文对基于生物信息学的乳白蚁属检疫分类鉴定和系统发育研究方法进行了介绍和评述,并对DNA技术在乳白蚁属分类和进化研究中的应用进行了讨论。 相似文献
117.
WEI GUO ZHI‐YONG WANG YI‐LEI WANG ZI‐PING ZHANG JIAN‐FANG GUI 《Molecular ecology resources》2005,5(2):369-371
Six polymorphic microsatellite markers were isolated and characterized using an enriched library technique in the large yellow croaker (Pseudosciaena crocea Richardson, 1864), a commercially important marine fish in China. They showed PIC (polymorphism information content) ranging from 0.064 to 0.885 (average of 0.580) and allele numbers ranging from two to 13 (average of 7.5), which were useful for the studies on population genetics and selective breeding of the large yellow croaker. 相似文献
118.
紫杉醇高产菌株的原生质体诱变选育及其遗传变异初探 总被引:16,自引:1,他引:15
以紫杉醇产生菌NCEU_1为出发菌株,分别采用紫外线和紫外线与氯化锂复合诱变方法对其原生质体进行诱变,获得了两株高产紫杉醇的突变株———UV4 0 - 1 9和UL50 - 6 ,其紫杉醇产量从出发菌株的314 0 7μg L分别提高至376 38μg L和392 6 3μg L ;同时,又采用RAPD和同工酶技术对出发菌株NCEU_1与两高产株UV4 0 - 1 9和UL50 - 6 间的遗传差异进行了研究。结果表明,出发菌株与诱变菌株之间以及两诱变菌株之间都存在明显差异,为进一步研究与紫杉醇合成相关基因及诱变株产量提高的分子机制奠定了基础 相似文献
119.
120.