橐吾属的起源、演化与地理分布

橐吾属Ligularia Cass．是菊科千里光族款冬亚族的一个大属。在款冬亚族中本属与大吾风草属 Farfugium Lindl．亲缘关系最近,但进化程度较高。本属包括6组,11系129种。所有种类均分布在 亚洲,仅2种扩散至欧洲。在东亚地区有119种,占该属总种数的96％。高度集中在横断山区的有4组、 6系67种,其中61种为特有种,占该属总组数的66％,总系数的54．5％,总种数的52％。这个事实 表明了横断山区是该属的多度中心和多样化中心。通过性状分析,伞房组伞房系Sect．Corymbosae, Ser．Calthifoliae叶肾形,具掌状叶脉,头状花序大而少,排列呈伞房状,总苞半球形,被认为是该属的 原始类群。原始种齿叶橐吾L. dentata和鹿蹄橐吾L.hodgsonii的分布区从我国四川东部经过湖北、湖 南、安徽、福建等省至日本。这个分布格局与近缘属大吴风草属Farfugium一致。 根据共同起源原理,这两个属的祖先极有可能就发生在这一地区。因此我们推测东亚地区从中国四 川东部至日本这一地区是本属的发源地,然而根据地质历史和现代分布,作者认为中国中部(包括四川 东部)是本属的初始起源地。该属起源后,基本上沿亚洲南缘的山地扩散,少数种类向东北至亚洲东北部。本属起源时间至少不晚于中白垩纪。     

Chronobiologic Evaluation of Blood Pressure in School Children

Blood pressure (BP) and heart rate (HR) data were collected over 24 h with an ambulatory BP monitor to (a) determine the existence of 12-, 24-, and combined 12- and 24-h BP patterns in children as previously noted for adults; (b) provide MESOR (an acronym for midline estimating statistics of rhythm), amplitude, and acrophase data for subgroups of students by race and gender; and (c) determine the influence of HR (as an estimate of activity) on BP and BP patterns for 100 normal, healthy students 9-12 years of age. We found no statistically significant differences between various racial groups or between gender for MESOR, amplitude, acrophase, or degree of sinusoidality of circadian rhythmicity (R² values) for BP; clinically interesting differences were observed, including lower MESOR BPs in Hispanic males when compared with their female counterparts and slightly higher MESOR BPs in blacks of both genders when compared with whites. In addition, we demonstrated subgroups of students who exhibited specific 24-h and combined 12- and 24-h patterns. Also, 67% of subjects showed stable or nonrhythmic BP patterns, perhaps related to BP sampling intervals. Differences in HR, as a surrogate measure of activity, accounted for 56% of the variation in systolic BP but only 26% in diastolic BP over the 24 h.     

Five-stranded β-sheet sandwiched with two α-helices: A structural link between restriction endonucleases EcoRI and EcoRV

Examination of crystal structures of restriction endonucleases EcoRI and EcoRV complexes with their cognate DNA revealed a common structural element, which forms the core of both proteins. This element consists of a five-stranded β-sheet and two α-helices packed against it and could be described as α–β sandwich in which helices and β-strands lie in two stacked layers. While the spatial structure of this α–β sandwich is conserved in both enzymes, there are no detectable similarities between amino acid sequences except of a few residues involved in active site formation. Probably, other restriction endonucleases which have similar organization of the active site might possess similar structural element regardless of DNA sequence recognized and recognition elements in the enzyme used. © 1994 Wiley-Liss, Inc.     

陇东黄土高原若干轮作技术方案水保效能评价分析

陇东黄土高原若干轮作技术方案水保效能评价分析李锋瑞,高崇岳（兰州大学生物系７３００００）（甘肃草原生态研究所兰州７３００２０）ＳｏｉｌａｎｄＷａｔｅｒＣｏｎｓｅｒｖａｔｉｏｎＥｆｆｉｃｉｅｎｃｉｅｓｏｆｓｅｖｅｒａｌＲｏｔａｔｉｏｎＰａｔｔｅｒｎｓｏ...     

九株根霉可溶性蛋白和三种酶的电泳图谱比较研究

本文报导了根霉属(Rhizopus) 9个菌株天然态及解聚态可溶性蛋白、酯酶同工酶、葡萄糖淀粉酶和SOD电泳图谱的比较研究。结果表明：可溶性蛋白图谱和酯酶同工酶谱能显示五种已知供试菌种间的差异,尤其酯酶同工酶谱还能显示米根霉两个供试菌株之间的微小差异。经综合分析全部试验结果后得出的系统树图显示了9个供试菌株间的亲缘关系,并为未知菌株F1(BR12)和Q303提供了鉴定和命名依据。文中首次报导了根霉的SOD同工酶,并对蛋白质和酶电泳图谱用于根霉分类研究进行了讨论。     

Fibrolast growth factors in the nervous system

Fibroblast growth factors (FGFs) exhibit widespread mitogenic and neurotrophic activities. Nine members of the family are currently known, and FGF-1 and FGF-2 are present in relatively high levels in CNS. FGF-1 is expressed by a subset of neuronal populations, while FGF-2 is expressed by astrocytes. FGF-1 and FGF-2 lack signal peptides and appear to be present mainly in inracellular compartmens. This suggests that the factors may act as initiators of a repair response after injury. Support for this notion comes from observations that FGF-1 and FGF-2 levels are low during critical phases of development, but high in the adult CNS. A family of transmembrane tyrosine kinase receptors (FGFRs) mediates the effects of FGFs. Four different genes coding for FGF receptors are currently known, three of which are expressed in cell type-specific patterns in the CNS The main receptor variants present in this tissue, however, can by themselves not distinguish between FGF-1 and FGF-2. Additional selectivity may be established by interaction of the FGFs and their receptors with select heparan proteoglycans (HSPGs). Therefore, the precise physiological role of FGFs is determined by the combination of cell type-specific patterns of expression of FGFs, FGFRs and HSPGs together with the mechanisms that regulate the extracellular availability of FGFs. 1994 John Wiley & Sons, Inc.     

Reaction norms and the genetic basis of phenotypic plasticity in the wing pattern of the butterfly Bicyclus anynana

The genetic basis of the dry-wet season polyphenism of wing pattern in response to temperature shown by Bicyclus anynana was studied, using a split-family design over four temperatures. Reaction norms crossed, but were only linear in the three highest temperatures, and only when larval development time was used as the environmental axis. Significant full-sib additive variances (V_A) and heritabilities (h²) for plasticity were found using slopes of reaction norms in a bootstrap procedure. Heritabilities were lower in intermediate temperatures, mainly due to differences in the residual variances (V_R). There was no clear trend in V_A across temperatures, contrary to the expectation that V_A would have been depleted by natural selection at the extreme temperatures and not depleted at the intermediate temperatures which occur less frequently in the field. Unpredictability in the onset of the following season at intermediate temperatures might lead to selection for diverse flresponses resulting in relatively high V_Rs. Theoretical models linking reaction norms to genetic parameters in separate environments were difficult to apply in this study, particularly because they are based on the assumption that V_Rs are constant. However the reaction norm approach combined with quantitative genetics provided a valuable insight into the evolution of the observed polyphenism.     

The fecundity patterns of S and L type rotifers of Brachionus plicatilis

Fecundity patterns of S and L type rotifers Brachionus plicatilis, which were previously found to have distinct growth ability, were analyzed using data of age-specific fecundity. The data were obtained by individual cultures of S and L type strains at 17, 24 and 34 °C. The pattern was analyzed by using normal probability functions. When the age was transformed into logarithmic value, the S and L types had an identical pattern of fecundity at every temperature. This fact indicates that the difference of the growth response to the temperature between S and L type strains stemmed only from the differences in net reproduction rate, not from the pattern.     

HOMOGENEITY OF THE GENETIC VARIANCE-COVARIANCE MATRIX FOR ANTIPREDATOR TRAITS IN TWO NATURAL POPULATIONS OF THE GARTER SNAKE THAMNOPHIS ORDINOIDES

Quantitative genetic models of evolution rely on the genetic variance-covariance matrix to predict the phenotypic response to selection. Both prospective and retrospective studies of phenotypic evolution across generations rely on assumptions about the constancy of patterns of genetic covariance through time. In the absence of robust theoretical predictions about the stability of genetic covariances, this assumption must be tested with empirical comparisons of genetic parameters among populations and species. Genetic variance-covariance matrices were estimated for a suite of antipredator traits in two populations of the northwestern garter snake, Thamnophis ordinoides. The characters studied include color pattern and antipredator behaviors that interact to facilitate escape from predators. Significant heritabilities for all traits were detected in both populations. Genetic correlations and covariances were found among behaviors in both populations and between color pattern and behavior in one of the populations. Phenotypic means differed among populations, but pairwise comparisons revealed no heterogeneity of genetic parameters between the populations. The structure of the genetic variance-covariance matrix has apparently not changed significantly during the divergence of these two populations.