排序方式: 共有91条查询结果,搜索用时 15 毫秒
51.
Genetic Variation and Evolution of the Alpine Bamboos (Poaceae: Bambusoideae) using DNA Sequence Data 总被引:9,自引:0,他引:9
Thamnocalamus , Fargesia and Yushania, of the alpine bamboos and one species of Ampelocalamus as an out-group were studied. The results indicated that Thamnocalamus spathiflorus var. crassinodus and the Fargesia spathacea clade form the basal groups but bootstrap support was weak. Among the rest of the species, including species previously placed
in Fargesia (plus Borinda) and Yushania, the F. yunnanensis subclade and the F. communis subclade were recognized but internal support for such groups was again low. The result indicated that, Fargesia and Yushania as delimited by morphological characters, are not monophyletic in the ITS phylogeny and require further resolution. We revealed
relatively high levels of genetic variability in the alpine bamboos and showed that the ITS region could be used to improve
generic delimitation of the woody bamboos in general.
Received 18 September 2000/ Accepted in revised form 9 May 2001 相似文献
52.
Yuan S Liu ZL Liu WJ Lei T Luo MH Du JB Wang JH Lin HH 《Zeitschrift für Naturforschung. C, Journal of biosciences》2007,62(5-6):403-409
"NYB" is a chlorophyll-less barley mutant, which grows relatively slow and unhealthily. The effects of water stress on photosystem II (PSII) of NYB and its wild type (WT) were investigated. Unexpected results indicated that the mutant was more resistant to water stress, because: PSII core proteins D1, D2 and LHCII declined more in WT than in NYB under water stress, and the corresponding psbA, psbD and cab mRNAs also decreased more dramatically in WT; CO2 assimilation, stomatal conductance, maximum efficiency of PSII photochemistry (Fv/Fm), efficiency of excitation energy capture by open PSII reaction centres (Fv'/Fm'), quantum yield of PSII electron transport (Phi(PSII)) and DCIP photoreduction in NYB were less sensitive to water stress than in WT, although the non-photochemical quenching coefficient (q(N)) and the photochemical quenching coefficient (q(P)) were almost the same in NYB and WT. Effective chlorophyll utilization and improved PSII protein formation in the mutant may be the reason for the enhanced stress resistance. Other possible mechanisms are also discussed. 相似文献
53.
利用巴斯德毕赤酵母(Pichia pastors)系统表达抗菌肽——牛乳铁多肽素(bovine lactoferricin,简称Lf-cinB),获得的分泌型表达产物具有较强的抗菌活性。首先将人工合成的LfcinB基因片段克隆到巴斯德毕赤酵母分泌型表达载体pPIC9K中,获得的重组质粒pPIC9K-LfcinB通过限制性内切酶SalⅠ酶切线性化,经电穿孔法转化入毕赤酵母细胞SMD1168内。G418抗性筛选,得到高拷贝转化子,经PCR检测LfcinB基因与毕赤酵母染色体稳定整合。阳性克隆经甲醇诱导表达LfcinB。结果表明,抗菌肽牛乳铁多肽素基因已经整合到酵母细胞基因组中并获得表达,表达产物具有较强的杀菌作用。 相似文献
54.
为了选育新的实验材料, 予以1个F2代玉米果穗上不同籽粒性状的分离比, 验证遗传学三规律, 依据遗传学三规律研究内容, 选择玉米第4对染色体上甜质胚乳基因Sn1sn1、第9对染色体上粒色基因C1c1和糯质胚乳基因Wxwx, 这3对基因所调控的相对性状为原始试材。经连续多代自交与测交、正交与反交, 严格选择, 终于选育出基因型纯合的亲本, 组配成杂交种。文章以“玉米基因交换值”和减数分裂所形成的配子类型、数量, 推导出理论值来衡量新的实验材料F2代同一个果穗上不同籽粒性状的分离比。结果显示: 自交穗呈现出3个 3︰1、2个9︰3︰3︰1、1个连锁交换, c2值均小于准许值。即准确、恰当验证遗传学三规律, 又将遗传学三规律融合在一起, 形成完整统一体, 选育出目前最新的实验材料。 相似文献
55.
Dear Editor,As the coenzyme of multiple carboxylases,biotin plays key roles in intermediary metabolism and animal nutrition(Listed 1990;Douglas,2017).Therefore,the analytical determination of biotin levels in diverse materials is a critical aspect of B-vitamin research.Microbiological assays are classic methods of measuring B-vitamin levels.Briefly,the growth of B-vitamin-dependent microorganisms is proportional to the amount of the specific B-vitamin in the medium,and the growth can be measured by assessing the change in the medium's turbidity. 相似文献
56.
基于叶绿体四个DNA片段联合分析探讨山茶属长柄山茶组、金花茶组和超长柄茶组的系统位置与亲缘关系 总被引:2,自引:0,他引:2
为探讨山茶属茶亚属(Camellia subgen.Thea)中长柄山茶组(sect.Longipedicellata)、金花茶组(sect.Chrysantha)和超长柄茶组(sect.Longissima)的系统位置和亲缘关系,本研究选取了该属4个亚属11组28个种及2个外类群的材料,对这些材料的叶绿体4个DNA片段(rp/16、psbA-trnH、trnL-F和rp/32-trnL)进行了测序,运用邻接法(neighbor-joining)、最大简约法(maximum-parsimony)和贝叶斯推断(Bayesian inference)对获得的序列进行了联合矩阵分析.并构建基因树.基因树的拓扑结构显示:1)金花茶组包括3个平行的支系,并且长柄山茶组的模式种长柄山茶(Camellia longipedicellata)嵌于其中一个支系,因而金花茶组可能是一个并系或多系类群;2)长柄山茶与越南分布的金花茶组种类在分子系统树上构成一个单系支,暗示了长柄山茶组和金花茶组之间可能具有紧密的亲缘关系;3)超长柄茶组不是一个单系类群,该组的河口超长柄茶(C.hekouensis)位于系统树的基部,与山茶属其余种构成姐妹群.由于缺乏更广泛取样的分析,超长柄茶在山茶属中的系统位置仍然不明确,超长柄茶组与长柄山茶组的亲缘关系问题也没有得到解决. 相似文献
57.
58.
59.
60.