Scaling of Folding Properties in Go Models of Proteins

Insights about scaling of folding properties of proteins are obtained bystudying folding in heteropolymers described by Go-like Hamiltonians. Bothlattice and continuum space models are considered. In the latter case, themonomer-monomer interactions correspond to the Lennard-Jones potential.Several statistical ensembles of the two- and three-dimensional targetnative conformations are considered. Among them are maximally compactconformations which are confined to a lattice and those which are obtainedeither through quenching or annealing of homopolymers to their compactlocal energy minima. Characteristic folding times are found to grow aspower laws with the system size. The corresponding exponents are notuniversal. The size related deterioration of foldability is found to beconsistent with the scaling behavior of the characteristic temperatures:asymptotically, the folding temperature becomes much lower than thetemperature at which glassy kinetics become important. The helicalconformations are found to have the lowest overall scaling exponent andthe best foldability among the classes of conformations studied. Thescaling properties of the Go-like models of the protein conformationsstored in the Protein Data Bank suggest that proteins are not optimizedkinetically.     

贵州疣螈骨骼系统的研究

本文运用硬骨-软骨双染色技术对贵州疣螈（Tylototriton kweichowensis）的骨骼系统做了较全面的观察研究,包括头骨、脊柱和前后肢带骨,并对各骨块的形状、位置以及与邻近骨块的关系都作了详细的描述。最后,将贵州疣螈与东方蝾螈、有斑肥螈的骨骼系统进行了比较,为揭示蝾螈科属间演化关系提供一定的依据。     

Chromosome Studies of 10 Species of Aconitum in China

This paper deals with chromosomal numbers and morphology of 10 species of Aconitum in China. According to the basic number of the genus (x=8), these species can be referred to diploid, tetraploid, hexaploid and octoploid. Correlation is found between chromosomal numbers, sizes and structures. The perennial species with a rhizome are mostly diploid, with chromosomes larger than those in the biennial species with a tuber, and their chromosome pairs 3-7 are mostly subterminal ones, whereas most biennial species are polyploid, and their chromosome pairs 3-7 are almost submetacentric. The evolutionary trends of chromosome from diploid to polyploid, large to small, st to sm are considered possible. The data are agreed with the idea that rhizomal species are more primitive than tuberous ones. The existence of two types of karyotypes in these 10 species is a further support of taxonomic division of two subgenera, subgen. Paraconitum and subgen. Aconitum. In addition, some species are taxonomically discussed.     

分子生物学技术在遗传病诊断中的应用

论述了遗传性疾病的发病机理和遗传病诊断的途径和策略,着重介绍了人类遗传疾病基因诊断技术的原理和发展状况,对该领域的新成果作了介绍和总结,对发展动向和存在的问题作了简要论述。 Abstract:The mechanisms of human genetic diseases and strategies to test human genetic diseases are discussed in the review.The development of the gene diagnosis techniques to genetic diseases and their principles are introduced emphatically.The new achievements in the field are valued and concluded,and the prospect and the difficulties in genetic diseases diagnosis are also briefly discussed.     

Early and Middle Jurassic Sporo-Pollen Assemblages of Qiquanhu Coal-Field of Turpan Xinjiang

One hundred and thirteen species of spores and pollens belonging to 58 genera were found from 66 core samples taken from two boreholes of the Early and Middle Jurassic deposits in the Qiquanhu coal-field of the Turpan Basin, Xinjiang have been investigated in this paper. Two of the species are described as new. Three sporo-pollen zones from lower to upper are described as follows: Sporo-pollen zone Ⅰ (equivalent bed: Badaowan Formation) . The pteridophytic spores are slightly more abundant than the gymnospermous pollen in this assemblage. The most abundant spores are Cyathidites minor, C. australis and Undulatisporites pflugii, U. taenus and so on. The second important fern spores are Osmundacidites, Lycopodiumsporites, Apiculatisporis and Duplexisporites. The most important gymnospermous genus is Cycadopites which ranks highest in the assemblage and includes C. nitidus and C. typicus.The other gymnospermous pollen include Classopollis, Pinuspollenites, Protoconiferus Piceites. Besides, there are a few pollen grains of Taeniaesporites and Chordasporites surviving from the Late Triassic in this assemblage. The present assemblage may be compared with the Early Jurassic sporopollen assemblage from the Daling Formation of the North-East Guangxi. Therefore, the Badaowan Formtion may be referred to Early Jurassic in age, probably Early Lias. Sporo-pollen zone Ⅱ (equivalent bed: Sangonghe Formation) In this assemblage the gymnosperms are predominant.Of them, Podocarpidites and Pinuspollenites increase obviously, and Quadraeculina and Protoconiferus are common. Few surviving elements are observed. The most abundant spores are those of Cyathidites, and the particularly abundant pollens are those of Cycadopites, This assemblage may be compared with the Late Lias sporo-pollen assemblage from the Fuxian Formation of the Northern Shangganning Basin. Therefore, the Sangonghe Formation should belong to Early Jurassic, probably Late Lias in age. Sporo-pollen zone Ⅲ (equivalent bed: Xishanyao Formation). The contents of the spores and pollens are almost equal in this assemblage. Cyathidites and Cycadopites are the most important spores and pollen. Osmundacidites and Quadraeculina are common. Neoraistrickia, Lycopodiumsporites and Eucommiidites troedssonii are present. Ancient striate bisaccate pollen disappears. The characteristics of this assemblage show some resemblances to those of the Middle Jurassic Yanan Formation in Chongxin county of Gansu province. So the Xishanyao Formation should belong to Middle Jurassic.     

Demonstration of rotational symmetries in alpha-keratin microfibrils of porcupine quill tip

Selected electron micrographs of transversely, obliquely and longitudinally sectioned microfibrils of transversely sectioned porcupine quill tip are shown to possess 2-fold radial, 3-fold radial and 5-fold polygonal rotational symmetries. These symmetries are verified with a rotation technique, and are similar to edge, corner and face projections of a pentagonal dodecahedron. The a-keratin microfibril is therefore suggested to be composed of a linear arrangement of morphologically identical microfibrillar subunits which approximate the shape of a pentagonal dodecahedron. The various line patterns present in electron micrographs of microfibrils are explained by different orientations of this three-dimensional shape within the thickness of the section. Previous electron microscopic models for the structure of the microfibrils are incompatible with these results. The image averaging methods used to arrive at these earlier models are discussed, and are thought to yield results which must differ from the demonstrated rotational symmetries.     

The ultrastructure of the tentacles of eleven species of dendrochirote holothurians studied with special reference to the surface coats and papillae

Summary The tentacles of eleven species of dendrochirote holothurians have been studied. The water vascular system, deep fibre system, ectoneural nerve ring and superficial fibre system are described and are similar to those of other holothurian tentacles. A conspicuous fuzzy coat covers the entire tentacular surface except for the tips of cilia. On the basis of its structure it is thought to be an attenuated glycocalyx. Its function is discussed in relation to anti-fouling and surface adhesion. The two surface coats underlying the fuzzy coat are termed the cuticle. Bacteria are found both within the surface coats and in the sub-cuticular space. Primary fixatives lacking osmium give poor preservation of the surface coats. The adhesive papillae of the apices of the tentacles contain elements of support cells and two other cells named Type-1 and Type-2 papillar cells. The secretions of Type-1 papillar cells are dense-cored vesicles and may contain a proteinaceous adhesive. The vesicles fuse with the cuticle and release their products which are apparently disseminated along the fuzzy coat filaments. The secretions of Type-2 papillar cells may have a neurosecretory function. The different models of food capture by dendrochirote tentacles are discussed as are duo-glandular adhesive systems in relation to dendrochirote tentacles.     

Potentiometric characterization of ethidium bromide and of its reactions with nucleic acids

A liquid membrane electrode that allows the concentration of ethidium ion (Ed(+)) to be measured selectively and accurately in the range of 0.1 microM to 5 mM is made. For Ed(+) concentrations less than 1 microM or more than 0.1 mM, the trend is no longer linear, and the causes of this behavior are discussed. The mean activity coefficient of ethidium bromide exhibits deviations from the Debye-Huckel limiting law that are interpreted in terms of aggregate formation. The stability constants for Ed(2)(2+) and Ed(2)Br(+) are 230 kg mol(-1) and 3.0 x 10(4) kg(2) mol(-2), respectively. In NaCl solutions, clusters involving up to 4 Ed(+) units are detected and their stability constants are evaluated. The intercalation of ethidium into poly(A).poly(U) in 1M NaCl is investigated by the above electrode, and the results are compared with those obtained by spectrophotometry. The data are analyzed in terms of Scatchard plots. The potentiometric method is more accurate than the spectrophotometric one at low values of the binding degree (r) where negative deviations from linearity are observed. The deviations are ascribed to a cooperative behavior rather than to artifacts caused by minor systematic errors.     

Differentiation of the plasma membrane of hepatic cells in monolayer cultures

Hepatocytes from rats were isolated by treatment with trypsin and cultured. Plasma membranes at different culture stages were observed by electron microscopy. The activities of 5' nucleotidase and adenosinetriphosphatase on the plasma membranes were examined. The cell coat was also studied by use of the concanavalin A-peroxidase technique. The surfaces of single cells, covered with microvilli, are the site of adenosinetriphosphatase activity only and are devoid of 5'-nucleotidase activity. After a few h of culture, the cells are grouped together in tight clusters or long trails and are separated by an intercellular space of 250 A, partially permeable to lanthanum nitrate. The juxtaposed plasma membranes on which 5'-nucleotidase and adenosinetriphosphatase activities occur also delimit spaces similar to bile canaliculi. The formation of junction complexes and their permeability to lanthanum nitrate was also studied. No enzymatic activity is observed at the junctions. The numerous tight junctions, impervious to the tracer, are always accompanied by a profusion of microfilaments. Mature desmosomes are rare, and are present only in the form of "maculae adhaerentes diminutae." The gap junctions, nearly always permeable to the tracer, form rapidly and assume a variety of shapes (trail, bulge and ring-like), the significance of which is open to discussion. The use of concanavalin A permits localization of the free sugar sites on the surface of the cells, in the pinocytotic vesicles and in the internal space of the gap junctions.     

The position of the Haplotaxidae in the evolution of oligochaete annelids

The Haplotaxidae have all the characteristics to support the hypothesis that they are the living descendents of the stem forms from which all of the Oligochaeta Clitellata (Orders Lumbriculida, Haplotaxida, Lumbricida, Tubificida) can be derived. The Aphanoneura are distinct from the Clitellata and are raised to a separate Class. There is no evidence to support the view that the elaborate setae of many Tubificida are derived from a polychaete ancestry; both are held to be independent modifications to aquatic life derived from a simple burrowing protoannelid with lumbricine setae.     

Areography of the Gymnosperms of China (1) Distribution of the Pinaceae of China

Nine of 10 genera and 119 of approximately 240 species of the Pinaceae occur in China, including 67 endemic species and two endemic genera. In this paper, the distributional maps of all the genera of the Pinaceae are presented (fig. 1-8). The horizontal and vertical distributions of species in each genus are discussed. The analysis of the distribution patterns of the genera indicates that some genera, such as Keteleeria, Tsuga, Pseudotsuga, Cathaya and Pseudolarix, are restricted to the area south of the Qinling Mountains and the Huaihe River, and the others, i. e. Picea, Abies, Larix and Pinus, extend northward to northeastern China. However, all of the genera except Keteleeria and Pinus are not found in very dry areas and tropical mountainous regions of China. The monotypic genera, Cathaya and Pseudolarix, are distributed in eastern and central China. The genus Keteleeria consists of 10 species, 7 of which are concentrated in southern Guizhou, northern Guangxi, southwestern Hunan and easternmost Yunnan. The distribution of the remaining 6 genera shows the maximum concentration in western Sichuan and northwestern Yunnan. (Figs. 2-8). Furthermore, more than third of species of the Pinaceae (37.8%) are also concentrated in western Sichuan and northwestern Yunnan. where a great variety of habitats and different topographic features occur. It is apparent that to conduct our systematic and evolutionary studies on this family in these region is especially needed. The relations between the areal size and the tolerance of species are discussed. The distributions of macrofossils and microfossils of the genera of the Pinaceae ia China are given, and it has been proved that areas of most genera of the family were considerably larger in the past. than at present.     

Fine structure of the corpus allatum of the female blow-fly Calliphora erythrocephala

Summary An electron microscopical study of the corpus allatum (CA) of the adult female Calliphora was undertaken.The cells have a very irregular shape. Light and dark cells are found. Mitochondria occur in great numbers. Microtubules are frequently observed. Free ribosomes are plenty, but rough-surfaced reticulum is scarce. Golgi complexes are not very conspicuous. Axons, mostly containing neurosecretory granules, are frequently found between the cells.The active corpus allatum is remarkable by the numerous lipid droplets and the abundance of tubular agranular reticulum. The reticulum sometimes forms aggregates from which vacuoles are budded off. The vacuoles lose their membrane, at the same time becoming slightly electron opaque, thus being transformed into lipid droplets.It is tentatively postulated that the hormone (or a precursor) is synthesized in the tubules of the agranular reticulum, collected in the vacuoles, and, when the membrane disintegrates, it is dissolved in lipid. The lipid droplets are thought to be released into the haemolymph through the surface of the gland or via intercellular channels.The inactive corpus allatum of the six days old sugar fed flies is small and more or less shrunken. The agranular reticulum is poorly developed, vacuoles are small, and lipid droplets few. The reticulum tends to form whorls, which eventually may possibly be transformed into myelin figures.We wish to express our gratitude to the Danish Natural Science Research Council for placing a Zeiss electron microscope at our disposal, and to the Carlsberg Foundation for supporting our work with grants. We are grateful to Prof. C. Overgaard Nielsen for laboratory facilities, and we are indebted to Mrs. Eva Jensen for her skilful technical assistance.     

松嫩平原野大麦无性系分蘖株的年龄结构

野大麦无性系分蘖株由３个龄级组成,为明显的增长型年龄结构、１龄级蘖在无性系生殖生长中占绝对优势。分蘖株龄级越高,其数量增长速率越小,对无性系物质积累的贡献越小,１、２龄级分蘖株数量和生物量均随着无性系丛径和总蘖数的增加而增长,３龄级蘖与总蘖数间呈直线相关。平均单蘖生产力随着龄级增加而下降。生殖蘖平均单蘖重具有相对稳定性。无性系中１龄级蘖平均单蘖重体现出一定的密度调节作用,无性系潜在种群也为明显的增     

Concepts of classic and modern biogeography: Contribution of Russian entomologists

The main stages and ways of development of insect biogeography in Russia are discussed. Three general research programs (studies of ranges, zones, and regions) are described. The role of the regional approach in biogeography is characterized. Some problems related to studies of insect ranges are evaluated, and the need for creating practical range maps is emphasized. The relationships between the insect distribution patterns and the life zones are discussed. The specific features of zonation in insect biogeography are noted. Special attention is paid to establishing the zones with unified population distribution patterns within a species range. The role of geozoological investigations and opportunities of modern information technologies are characterized relative to evaluation of general patterns of insect assemblage distribution. The problems of regionalization in insect biogeography are discussed. Three main approaches (intuitive, a priori, and a posteriori) are determined. Some advantages of using population and assemblage distribution patterns in regionalization are emphasized. The role and possibilities of insect biogeography studies for in the field of reconstruction of past and long-term forecasting are characterized.     

Norms of size and annual increments of six anatomical measures of the cranium in boys and girls from four to fifteen years of age

Norms of size and annual increments of six cranial dimensions are presented. The sample consists of 20 boys and 23 girls observed longitudinally from 4 to 15 years of age. The reported measurements are corrected for magnification of distortion and represent actual size rather than a roentgenographic projection. The dimensions of the cranial vault are observed to be closer to the adult size at age four years than the dimension involving the cranial base. The cranial base dimension continues to grow until adolescence. The elongation in cranial base dimensions during adolescence may be attributed to bone deposition on glabella.     

Subsurface cisterns in the Purkinje cells of cerebellum of Syrian hamster

Summary Three types of subsurface cisterns were observed in Purkinje cells of the cerebellum of the Syrian hamster. The type-1 cisterns are subsynaptic, related to axosomatic synapses, and are separated from the postsynaptic cell membranes with distances of 400–800 Å. These are probably modified rough surfaced endoplasmic reticulum. The type-2 cisterns are closely apposed to the surface membranes of Purkinje cells, and have very little intracisternal space except at the dilated lateral edges. The type-3 cisterns are similar in structure to the type-2 cisterns but in addition are closely associated with mitochondria. The type-2 and type-3 cisterns appear between one and two weeks after birth and are still present in adults, having almost the same frequency of occurrence. Thin cell processes opposite the type-2 and type-3 cisterns are considered to be glial cell processes. The morphological details of these types of subsurface cisterns are described here, and their possible functional significance is briefly discussed.This work was carried out at the Department of Anatomy, University of Minnesota, Minneapolis, USA, and was supported by grants from the China Medical Board of New York and Anatomical Training Grant GM114 from the USPHS.Dr. Takahashi wishes to express his sincere thanks to Dr. A. Lazarow and Dr. R. L. Wood of the Department of Anatomy, University of Minnesota, who enabled him to use facilities for electron microscopy.     

The effect of age on the ultrastructure of the mid-gut cells of the hymenopteran Nasonia vitripennis (Walk.) (Hymenoptera,Pteromalidae)

Summary The ultrastructure of the mid-gut cells of aged female Nasonia vitripennis is described. The mid-gut is a shrunken and distorted organ in the aged animal. The individual cells are highly disorganised and the organelle components are altered. The small lipid droplets formed in the apical cell region do not coalesce to form the large central lipid inclusions characteristic of the young animal. The rough endoplasmic reticulum is reduced and some of the mitochondria enlarge. The mid- and apical cell regions also contain large numbers of cytolysosomes. The basal cell region is essentially unchanged, but the channels formed by the infolded basal plasma membranes are dilated. The changes observed are discussed in relation to previous observations on other insect species.We are indebted to Professor E.W. Knight-Jones in whose Department this work was carried out, and to the Science Research Council for financial support to one of us (I.D.)     

普通齿蛉幼虫的呼吸系统及呼吸行为

研究了普通齿蛉Neoneuromus ignobilis Navás幼虫的呼吸系统及其呼吸行为。结果表明:普通齿蛉幼虫为全气门式(10对气门)呼吸系统,前中胸、中后胸之间、腹部8节各有1对气门,腹部8节各有气管鳃1对,前6对细短,管状,有较短绒毛,后2对气管鳃较粗长,呈羽毛状。腹部1～7节各有1对毛簇,第8腹节无毛簇。侧纵干气管较粗,4束,自前胸前缘部分成左右2组,每组两根侧纵干气管,向胸腹部延伸,二级气管分别伸达各个气门和毛簇,腹部每节由毛簇处的二级气管分支而来的三级气管相连或延伸至消化道等处。气管鳃中无气管。有毛簇呼吸、气门呼吸和体壁呼吸3种呼吸方式,在水中以毛簇呼吸为主,在陆上进行气门呼吸和体壁呼吸。     

Wood, bark and stem anatomy of New World species of Gnetum

Quantitative and qualitative data are presented for 11 collections of six species. The wide range of character states for the species is presented in the form of a key to emphasize their potential systematic correlations. Distinctive among these are phcllem characteristics. Fibre-tracheids are newly reported for lianoid Gnetum species. Cells previously thought to be like companion cells in secondary phloem are shown to be uniseriate rays, counterparts to uniseriate xylem rays. Laticifers are abundant in most of the species, and are newly described for secondary tissues of Gnetum. Presence of tyloses in laticifers of two species is apparently a new report for vascular plants. Tori are present in two New World Gnetum species, adding to the report in African species. Perforation plates are simple except near or in primary xylem, where they are simple or foraminate. Torus presence and foraminate perforation plate presence are features more reminiscent of Ephedra and other gymnosperms than of angiosperms. The bark of Gnetum is also very similar to that of Ephedra.     

沉香叶解剖结构的研究

通过石蜡切片法,光学显微镜观察,研究了沉香叶的解剖结构。结果表明,沉香叶为典型的异面叶,但具有许多旱生特征。表皮由一层排列紧密的形状不规则的表皮细胞组成,细胞外壁角质膜较厚,上表皮角质膜较下表皮的厚3.48μm,下表皮上零星分布着单细胞表皮毛,气孔类型为无规则型,仅分布在下表皮上,微下陷;叶肉组织发达,其间分布着较多的长方晶体,其长轴与表皮垂直;栅栏组织由1～2层圆柱形细胞组成,其外层细胞转化为异细胞,栅栏组织∶海面组织为1∶3.5,下表皮内具有1～2层由异细胞组成的下皮层;主脉发达,有异细胞组成的维管束鞘,具内生韧皮部;叶内具有发达的木质部外纤维。以上特征反映出植物结构与环境的统一性。