Low genetic diversity and population connectivity fuel vulnerability to climate change for the Tertiary relict pine Pinus bungeana

Endemic species are important components of regional biodiversity and hold the key to understanding local adaptation and evolutionary processes that shape species distributions. This study investigated the biogeographic history of a relict conifer Pinus bungeana Zucc. ex Endl. confined to central China. We examined genetic diversity in P. bungeana using genotyping-by-sequencing and chloroplast and mitochondrial DNA markers. We performed spatial and temporal inference of recent genetic and demographic changes, and dissected the impacts of geography and environmental gradients on population differentiation. We then projected P. bungeana's risk of decline under future climates. We found extremely low nucleotide diversity (average π 0.0014), and strong population structure (global F_ST 0.234) even at regional scales, reflecting long-term isolation in small populations. The species experienced severe bottlenecks in the early Pliocene and continued to decline in the Pleistocene in the western distribution, whereas the east expanded recently. Local adaptation played a small (8%) but significant role in population diversity. Low genetic diversity in fragmented populations makes the species highly vulnerable to climate change, particularly in marginal and relict populations. We suggest that conservation efforts should focus on enhancing gene pool and population growth through assisted migration within each genetic cluster to reduce the risk of further genetic drift and extinction.     

九种蹄盖蕨科植物配子体的酯酶同工酶分析

本文培养了蹄盖蕨科９个种即中华蹄盖蕨（Ａｔｈｙｒｉｕｍｓｉｎｅｎｓｅ）带岭蹄盖蕨（Ａ．ｄａｌｉｎｇｅｎｓｅ）、多齿蹄盖蕨（Ａ．ｍｕｌｔｉｄｅｎｔａｔｕｍ）（包括青柄和紫柄２种带岭蹄蕨类型）、东北蛾眉蕨（Ｌｕｎａｔｈｙｒｉｕｍｐｙｃｎｏｓｏｒｕｍ）、朝鲜介蕨（Ｄｒｙｏａｔｈｙｒｉｕｍｃｏｒｅａｎｕｍ）、山冷蕨（Ｃｙｓｔｏｐｔｅｒｉｓｓｕｄｅｔｉｃａ）、假冷蕨（Ｐｓｅｕｄｏｃｙｓｔｏｐｔｅｒｉｓｓｐｉｎｕｌｏｓａ）、欧洲羽节蕨（Ｇｙｍｎｏｃａｒｐｉｕｍｄｒｙｏｐｔｅｒｉｓ）和黑鳞短肠蕨（Ａｌａｎｔｏｄｉａｃｒｅｎａｔａ）的配子体为材料,进行酯酶同工酶的分析,以表明它们的种间差异,其中多齿蹄盖蕨的青柄和紫柄两种类型的酶谱存在明显差异,应考虑紫柄为多齿蹄盖蕨的变型。     

Evidence for the presence of β-lactamase inStreptomyces glaucescens and its inhibition by sodium clavulanate

Streptomyces glaucescens is shown to possess -lactamase activity which is inhibitable by clavulanate. This is important in regard to its use as a cloning host for enzymes of \-lactam biosynthesis.     

一例智力低下患者7q~ 标记染色体的来源鉴定

以人类染色体显微切割、PCR技术构建的现有人类染色体特异性和染色体区带特异性探针池作为绘画探针,采用正向染色体绘画技术,结合染色体筛查方法,查明了一例7q~ 标记染色体患者的染色体附加片段来源于3q26→3qter。确定该患者的核型为46,XX,-7, der(7)t(7;3)(7pter→7q32::3q26→3qter)。应用这个策略,能够快速有效地鉴定标记染色体的来源。     

抗人肺腺癌单克隆抗体重,轻链可变区基因的分离克隆和序列测定

根据鼠免疫球蛋白重。轻链可变区基因ＦＲ１和ＦＲ４的序列保守性,化学合成了适于体外扩增Ｉｇ重、轻链可变区基因（Ｖ_Ｈ和Ｖ_Ｌ）的数对引物。以分泌抗人肺腺癌单抗的杂交瘤细胞株ＷＬＡ－２Ｃ４的基因组ＤＮＡ为模板,ＰＣＲ扩增Ｖ_Ｈ和Ｖ_Ｌ基因,分别克隆人ｐＵＣ１９载体。转化子经蓝、白斑筛选,酶切鉴定,双脱氧测序证实确为鼠单抗可变区基因,其中Ｖ_Ｈ基因全长为３４８ｂｐ,编码１１６ａａ,属重链ⅡＢ亚类;Ｖ_Ｌ基因全长３１８ｂｐ,编码１０６ａａ,属Ｋ轻链Ⅵ亚类。     

水稻矮缩病毒第11号组分基因序列和编码蛋白的功能分析

水稻矮缩病毒(Rice Dwarf Virus-RDV)广泛分布于中国、日本及东南亚地区,侵染水稻和禾本科其它一些作物,是造成水稻减产的主要原因之一,对农作物危害极大。RDV属于呼肠孤病毒科(Re-oviridae)中的植物呼肠孤病毒属(Phytoreovirus)成员,其病毒粒子直径70nm,为20面体,有双层     

Incorporating an Asymptotic Parameter into the Weibull Model to Describe Plant Disease Progress

The Weibull model is a flexible growth model that describes both general population growth and plant disease progress. However, lack of an asymptotic parameter has limited its wider application. In the present study, an asymptotic parameter K was introduced into the original Weibull model, written as; y = K {1 − exp [− ( t − a ) ^c ]}, in which a , b , c and K are location, scale, shape, and asymptotic parameters, respectively, y is the proportion of disease and t is time. A wide range of simulated disease progress data sets were generated using logistic, Gompertz and monomolecular models by specifying different parameter values, and fitted to both original and modified Weibull models. The modified model provided statistically better fits for all data than the original model. The modified model can thus improve the curve-fitting ability of the original model which often failed to converge, especially when the asymptote is less than 1.0. Actual disease progress data on wheat leaf rust and tomato root rot with different asymptotic values were also used to compare the original and modified Weibull models. The modified model provided a statistically better fit than the original model, and model estimates of asymptotic parameter K were nearly identical to the actual disease maxima reflecting the characteristics of the host-pathosystem. Comparison of logistic, Gompertz, and Weibull models including parameter K by fitting to the observed data on wheat leaf rust and tomato root rot revealed the applicability of the modified Weibull model, which in a majority of cases provided a statistically superior fit.     

环境中富啡酸对小麦吸收利用亚硒酸钠及其毒性的影响

利用小麦水培安验,研究了从土壤中提取的富啡酸（Ｆｕｌｖｉｃａｃｉｄ,ＦＡ）对亚硒酸钠生物有效性及毒性的影响。结果表明,富啡酸对小麦吸收利用亚硒酸钠有明显的影晌,并且对高浓度亚硒酸钠的毒性有一定的抑制作用,富啡酸可提高小麦对硒胁迫的生态适应性。     

日本网纹甜瓜引种试验初报

本文报道日本网纹甜瓜在桂北地区引种结果。夏系品种较春系品种更适应桂北地区气候条件。控制蔓枯病的发生是引种成功的关键。     

城郊景观动态模型研究──以沈阳市东陵区为例

基于渗透理论、马尔柯夫过程理论,采用中性模型方法,建立了3个不同的城郊景观动态模型,模型中分别介入不同自然因子和决策因子.利用模型对研究区景观进行了动态变化模拟.对模拟结果进行了评价,评价方法与指标包括:1)多分辨率拟合分析;2)最近邻概率;3)斑块大小和数目.结果发现,综合介入决策因素和自然因子的模型具有最好的效果.