An assessment of the AFLP method for investigating population structure in the red alga Chondrus crispus Stackhouse (Gigartinales, Florideophyceae)

The appropriateness of the Amplified Fragment Length Polymorphism (AFLP) technique for investigating Chondrus crispus Stackhouse populations in the Maritime Provinces of Canada was assessed. The AFLP procedure was first subjected to reproducibility testing and three shortcomings were noted: 1) failure to reproduce band intensity between replicate runs for the same individual and primer pair; 2) failure of some bands to replicate; 3) lack of reproducibility for complete replicate runs for some individuals and primer pairs. In the last-mentioned case, the lack of reproducibility resulted in characteristic electropherograms indicative of weak reactions. These weak runs can be attributed to poor restriction digest/ligation reactions and/or substandard PCR, these failures ultimately resulting from low and inconsistent DNA quality. We recommend that reproducibility testing should be completed routinely in studies using the AFLP technique. In the current work, only fragments and individuals that gave reproducible results were used in subsequent analyses. The AFLP method resulted in highly variable markers within and between the populations of C. crispus included in this investigation, which prevented successful resolution of population structure. This situation could result from a lack of suitability for AFLP markers in population genetic studies, and/or too extensive genetic variation for C. crispus populations to be discerned by the AFLP technique. These two possible explanations are discussed. This revised version was published online in August 2006 with corrections to the Cover Date.     

Contrasting floral biology of Artabotrys species (Annonaceae): Implications for the evolution of pollinator trapping

Artabotrys comprises a species-poor early divergent grade (EDG) and a main species-rich clade (“main Artabotrys clade,” MAC). All members of the MAC exhibit a remarkably well-conserved floral Bauplan characterized by a tightly enclosed floral chamber with an elaborate rim between the inner petal blade and claw. Conversely, EDG resembles the sister genus Xylopia in lacking the inner petal rim, with one species (Artabotrys brachypetalus) bearing petals that lack the distinction between blade and claw altogether. The floral phenology and pollination ecology of two exemplar species—Artabotrys brachypetalus from the EDG and Artabotrys blumei from the MAC—are compared, including assessment of effective pollinators and their activity patterns, scent chemistry and thermogenesis. Our study revealed that Artabotrys blumei exhibits abbreviated anthesis (c. 27 hr), with a floral phenology and morphology that are clearly consistent with pollinator trapping, and may be pollinated by small beetles. Artabotrys brachypetalus has a typical anthetic duration (c. 45 hr), lacks a pollinator trapping mechanism, and is pollinated by honey bees and curculionid beetles. The “xylopioid” traits of the EDG are likely to be plesiomorphic, whereas the tightly enclosed floral chamber is likely to be apomorphic for the MAC and functionally significant in trapping pollinators.     

马铃薯StMYB44基因对蔗糖的响应

MYB转录因子存在于所有真核生物中,是最具代表的转录因子家族之一,广泛参与植物发育、苯丙烷代谢、生物与非生物胁迫响应、激素响应以及细胞形态建成等过程。该研究从马铃薯品种‘青薯9号’中克隆得到StMYB44基因(GenBank登录号XM_006367359.2),该基因CDS长为963 bp,编码320个氨基酸,含有2个SANT结构域。实时荧光定量PCR结果显示,StMYB44基因在花中表达最高,在匍匐茎中表达最低;且StMYB44基因在无蔗糖处理下表达上调,在高浓度蔗糖处理下(6%、9%)表达下调。构建表达载体并进行遗传转化烟草发现,StMYB44基因突变体在无蔗糖条件下的长势明显好于野生型,而在高蔗糖浓度下(6%、9%)的长势弱于野生型,且蔗糖浓度越高,差异越大。研究表明,蔗糖浓度能够调节StMYB44基因的表达,推测StMYB44基因可能在植物响应蔗糖中起重要作用。     

宁夏兽类一属、种新纪录——淡灰豹鼩（Pantherina griselda Thomas，1912）

正淡灰豹鼩(Pantherina griselda)隶属于鼩形目(Soricomorpha)鼩鼱亚科(Soricinae)豹鼩属(Pantherina),其模式产地为中国甘肃省临潭县(Thomas,1912)。由于淡灰豹鼩整体形态与黑齿鼩鼱属(Blarinella)中的原甘肃川鼩(B.griselda)相似,且二者同域分布,曾被记录为黑齿鼩鼱属中的一个隐存种Blarinella sp.(Bannikova et al.,2017);He等     

云南新平铁坚油杉森林群落结构特征

摸清珍稀濒危抗旱植物铁坚油杉(Keteleeria davidiana)的种群数量及其分布情况, 能够为珍稀濒危物种保护工作提供基础数据。该文对云南省新平县6个乡镇铁坚油杉群落进行样方调查分析, 每个乡镇设置3个样方, 样方面积为20 m × 20 m, 记录样方生境信息、统计群落物种组成及其数量特征, 对群落类型及其结构特征进行了统计和分析。主要结果: (1)在调查样地内, 共有维管束植物163种, 隶属于58科131属; (2)植物群落区系分布类型有12种, 以热带成分和中国特有种为主, 热带成分占优势; (3)群落内乔木和灌木植物最多, 占62.58%, 其次是多年生草本植物; (4)按照建群种和生活型, 可将18组植被样方数据划分为3个群系17个群落类型; (5)年龄结构不合理, 铁坚油杉种群结构呈衰退趋势, 自然居群已成为小种群。如果铁坚油杉群落没有足够的幼苗进行更新和补充, 铁坚油杉将退出当前的群落。     

A New Method for the Preparation of Minicells for Physiological Studies

A procedure has been developed for preparing minicells that does not rely on sucrose gradients in a rate-zone centrifuge. In the presence of low levels (10 units/ml) of penicillin, the contaminating bacteria present in minicell cultures after low-speed differential centrifugation are turned into long filamentous cells and can be killed by sonic treatment. An additional low-speed centrifugation (2, 000 g for 5 min) yields purified minicells with less than one contaminating cell per 10 minicells.     

A Computational Model of Lipopolysaccharide-Induced Nuclear Factor Kappa B Activation: A Key Signalling Pathway in Infection-Induced Preterm Labour

Preterm birth is the single biggest cause of significant neonatal morbidity and mortality, and the incidence is rising. Development of new therapies to treat and prevent preterm labour is seriously hampered by incomplete understanding of the molecular mechanisms that initiate labour at term and preterm. Computational modelling provides a new opportunity to improve this understanding. It is a useful tool in (i) identifying gaps in knowledge and informing future research, and (ii) providing the basis for an in silico model of parturition in which novel drugs to prevent or treat preterm labour can be “tested”. Despite their merits, computational models are rarely used to study the molecular events initiating labour. Here, we present the first attempt to generate a dynamic kinetic model that has relevance to the molecular mechanisms of preterm labour. Using published data, we model an important candidate signalling pathway in infection-induced preterm labour: that of lipopolysaccharide (LPS) -induced activation of Nuclear Factor kappa B. This is the first model of this pathway to explicitly include molecular interactions upstream of Nuclear Factor kappa B activation. We produced a formalised graphical depiction of the pathway and built a kinetic model based on ordinary differential equations. The kinetic model accurately reproduced published in vitro time course plots of Lipopolysaccharide-induced Nuclear Factor kappa B activation in mouse embryo fibroblasts. In this preliminary work we have provided proof of concept that it is possible to build computational models of signalling pathways that are relevant to the regulation of labour, and suggest that models that are validated with wet-lab experiments have the potential to greatly benefit the field.