特异腐质霉纤维素酶的研究

由腐植土中分离到一株嗜热真菌,经鉴定为特异腐质霉(Humicola insolens Cooney etEmerson)。研究了这株菌纤维素酶的产生条件和一般性质。菌在含麦麸5％、NaNO0.3％的液体培养基(灭菌前pH7.5,灭菌后pH7.2)中,于45℃培养4天,以羧甲基纤维素钠为底物,每ml滤液酶活力为20个单位。酶作用的最适条件为:pH6.0,温度为65—70℃。该纤维素酶是一种耐热酶,热稳定性较强,70℃保温5分钟后,酶活力剩余88％。底物对该酶的热钝化有较强的保护作用,无底物存在条件下,70℃保温6小时后,酶活力仅剩余1％,而在同样的处理温度和时间,在有底物存在条件下,酶活力可剩余30％。该酶在45℃保温15小时的条件下,pH稳定范围为6.0—9.0。     

Evolutionarily singular strategies and the adaptive growth and branching of the evolutionary tree

We present a general framework for modelling adaptive trait dynamics in which we integrate various concepts and techniques from modern ESS-theory. The concept of evolutionarily singular strategies is introduced as a generalization of the ESS-concept. We give a full classification of the singular strategies in terms of ESS-stability, convergence stability, the ability of the singular strategy to invade other populations if initially rare itself, and the possibility of protected dimorphisms occurring within the singular strategy's neighbourhood. Of particular interest is a type of singular strategy that is an evolutionary attractor from a great distance, but once in its neighbourhood a population becomes dimorphic and undergoes disruptive selection leading to evolutionary branching. Modelling the adaptive growth and branching of the evolutionary tree can thus be considered as a major application of the framework. A haploid version of Levene's soft selection model is developed as a specific example to demonstrate evolutionary dynamics and branching in monomorphic and polymorphic populations.     

鸡PPARγ基因的表达特性及其对脂肪细胞增殖分化的影响

为分析鸡PPARγ基因的组织表达特性及其在脂肪细胞增殖和分化过程中的功能,文章以东北农业大学高、低腹脂双向选择品系肉鸡为实验材料,利用Western blotting方法,检测PPARγ基因的组织表达特性及其在高、低脂系肉鸡腹部脂肪组织间的表达差异;采用RNAi技术,在鸡原代脂肪细胞中抑制PPARγ基因的表达后,通过MTT和油红O提取比色的方法,研究鸡PPARγ基因对脂肪细胞增殖和分化的调控作用;利用Real-timePCR和Western blotting技术,分析PPARγ基因表达下调后,其他脂肪细胞分化转录因子以及与脂肪细胞分化相关的重要基因的表达变化情况。结果表明,PPARγ基因在7周龄高脂系肉鸡腹部脂肪组织、肌胃、脾脏、肾脏组织中表达量较高,在心脏中表达量较低,在肝脏、胸肌、腿肌、十二指肠中未检测到表达信号;与高脂系相比,PPARγ基因在5和7周龄低脂系肉鸡腹部脂肪组织中的表达量较低(P<0.05);PPARγ基因的表达量下降后,鸡脂肪细胞的增殖能力增强,分化能力减弱;同时,C/EBPα、SREBP1、A-FABP、Perilipin1、LPL、IGFBP-2基因的表达量均下降(P<0.05)。由此可见,PPARγ基因的表达可能与肉鸡腹部脂肪的沉积有一定的关系,该基因可能是调控鸡脂肪细胞增殖与分化的关键因子。     

Multimodal signals in male European treefrog (Hyla arborea) and the influence of population isolation on signal expression

In nocturnal treefrogs, mate choice implies the use of acoustic and visual signals. Multimodality is suspected to have evolved for either information redundancy or information complementariness. It is essential to explore multimodality in a natural context to understand the selection pressures operating on the signals. In the present study, we investigated calling and coloration in relation to male biometry and condition in four populations of European treefrog (Hyla arborea) varying in size and genetic isolation. We compared the signal intensity between core and satellite populations to estimate the impact of genetic diversity on male secondary sexual traits. The results obtained show important regional variations in both traits, likely as a result of local adaptations. Call and coloration are weakly correlated within an individual, implying that these traits likely convey different information about the signaller's identity or quality, thus supporting the hypothesis of complementariness of multiple messages. By contrast to the experimental evidence, we find that call and coloration are not related to male condition (as estimated by the residual of mass over size), suggesting that the condition‐dependence of these traits may be mediated by complex mechanisms not accurately reflected by the chosen estimator. Finally, male call and colour phenotypes present no robust pattern of variation with isolation status, probably because of variation in local selective pressures and in history of population dynamics. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 103 , 633–647.     

Male preponderance in early diagnosed type 2 diabetes is associated with the ARE insertion/deletion polymorphism in the <Emphasis Type="Italic">PPP1R3A</Emphasis> locus

Background  

The ARE insertion/deletion polymorphism of PPP1R3A has been associated with variation in glycaemic parameters and prevalence of diabetes. We have investigated its role in age of diagnosis, body weight and glycaemic control in 1,950 individuals with type 2 diabetes in Tayside, Scotland, and compared the ARE2 allele frequencies with 1,014 local schoolchildren.     

Up-regulation of multiple serine proteinases during earthworm tail regeneration

Summary

Previous studies have shown that spatiotemporal regulation of extracellular matrix (ECM) by proteinases is implicated in the initial step of regeneration. In amphibian regeneration, the up-regulation of proteinases such as metalloproteinases (MMPs) and cathepsin D, and proteinase-related proteins such as proteinase tissue inhibitors and activators has been demonstrated. Since the earthworm could provide a unique and valuable model to investigate the mechanism of regeneration, we studied the developmental change in proteinase expression during earthworm tail regeneration. Zymographic analysis revealed that proteinase activities began to increase within 1 h after amputation and reached a maximum at 7 days post-amputation. This peak in activity was approximately 22-fold greater than the unamputated controls. Thereafter, the proteinase activities tended to decrease followed by another peak at 30 days before returning to control levels. At least four types of proteinase were distinguishable at 7 and 30 days post-amputation, with molecular weights of 25, 28, 38, and 44 kDa, respectively. All proteinase activities were strongly inhibited by addition of phenylmethylsulfonyl fluoride (PMSF) and aprotinin, specific inhibitors for serine proteinase. Pepstatin A, E-64, iodoacetamide and a metal ion-free medium were not effective inhibitors, indicating that proteinases expressed during earthworm tail regeneration would be serine proteinases. In addition, we were able to detect two types of plasminogen activator (PA) with molecular weights of 40 and 47 kDa, respectively. PA activities were predominantly expressed at 1, 5, and 25 days post-amputation, which preceded two peaks of serine proteinase activities appearing at approximately 7 and 30 days after amputation, respectively. This fact supports the view that serine proteinases expressed in respond to tail amputation may be plasmin-like proteinases activated by PA.     

蟋蟀对召唤声识别的趋声性定位行为

为了探究蟋蟀种内个体间的声音通讯原理,本研究通过回放利用Cool-edit2000声音采集软件采集的双斑蟋Gryllus bimachlatus召唤声,分别对雌、雄蟋蟀识别召唤声的趋声性定位行为进行了观测研究。实验结果表明:雌、雄双斑蟋对回放的召唤声均有较强的识别反应,但雌蟋蟀的趋声定位性较强,能在较短的时间内积极寻找到声源,路径成"s"型;雄蟋蟀反应相对较弱,路径较长,找到声源时间比雌蟋蟀长。本研究结果揭示召唤声在蟋蟀种内通讯中不仅对个体间的联系有作用,对异性求偶也有重要作用。