无瓣海桑和白骨壤植株根系时空分布特征

无瓣海桑和白骨壤是我国红树林造林中较具代表性的两种植物,通过对10龄无瓣海桑纯林、10龄白骨壤纯林、6龄无瓣海桑纯林和6龄白骨壤纯林的调查分析发现:1)无瓣海桑和白骨壤植株根系水平分布的半径和地下根系垂直深度均随树龄的增加而增加,其中10龄无瓣海桑和白骨壤植株的水平分布半径分别为30.6 m和3.85 m,6龄无瓣海桑和白骨壤植株的水平分布半径为9.47 m和2.23 m; 10龄和6龄无瓣海桑和白骨壤植株的地下根系分布深度分别为60 cm和40 cm; 2)无瓣海桑和白骨壤植株地表呼吸根系密度、高度、基径的分布范围会随其树龄的增加而增加,但其根系密度、高度和基径总体表现为由树冠向外逐渐减小; 3)无瓣海桑和白骨壤植株地下根系主要分别于0—20 cm表层,地下根系密度随树龄的增加而增多,具体如10龄无瓣海桑和白骨壤根系分布深度为60 cm,其中76.3%和77.6%根系分布于0—20 cm深度; 6龄无瓣海桑和白骨壤根系分布深度为40 cm,其中91.9%和91.6%根系集中于0—20 cm土层。这些结果能为进一步理解红树林的促淤保滩功能提供新启示。     

Distribution and Identification of an Invasive Gracilaria Species that is Hampering Commercial Fishing Operations in Southeastern North Carolina, USA

A newly abundant Gracilaria species in the sounds of southeastern North Carolina has become a problem for commercial fishing and industries drawing water from the lower Cape Fear River. DNA sequence analyses have shown that this species is Gracilaria vermiculophylla, a taxon originally described from East Asia. Surveys for G. vermiculophylla have shown that it has a discontinuous distribution in the sounds of southeastern North Carolina, and suggest that it is spreading. Gracilaria vermiculophylla meets 6 of the 10 criteria used to help identify invasive species in that it has only recently appeared in southeastern North Carolina; is associated with human mechanisms of dispersal; has a restricted distribution; has disjunct populations in isolated oceans; no means of active dispersal, and an exotic evolutionary origin. The species may also meet two additional criteria as its local range is believed to be expanding, and it is filling a previously unoccupied seasonal niche. These factors taken together strongly suggest that G. vermiculophylla is an invasive species in southeastern North Carolina.     

The Exact Distribution of the Anderson-Kannemann Statistic

The Anderson-Kannemann test is a rank test for treatment effects in a randomized block design with K treatments and N blocks. In this paper, an algorithm for computing the exact distribution of the Anderson-Kannemann test statistic under the null hypothesis is deduced. Then, the exact distribution is compared with the asymptotic χ²-distribution, and it is shown that the exact distribution is approximated fairly well by the asymptotic distribution. Tables of the exact distribution are given for K = 3, N = 3(1)15; K = 4, N = 3(1)11; K = 5, N = 3(1)7; and K = 6, N = 3(1)5.     

Dispersal distance of corn pollen under fluctuating diffusion coefficient

I develop a mechanistic model for pollen dispersal by a generalization of the Brownian motion model. This model provides an explanation as to why the distribution of the dispersal distance is leptokurtic in most organisms. The pollen is assumed to move in a period between and + to the circumference of a circle of radius r that has a center at the current position. The angle of movement is chosen at random. Unlike the conventional Brownian motion model, the step length, r, fluctuates in a stochastic manner, obeying a generalized gamma distribution. The convection flow, i.e., the directional movement of pollen, is also considered. I show that this model is identical to the diffusion model where the dispersal duration weighted by the diffusion coefficient obeys a gamma distribution. Hence, the model is called the gamma model. The solution is given in an explicit form. The model is fitted to six data sets obtained from the literature by maximizing the quasi-likelihood. Another model (the inverse gamma model), which is not a mechanistic model but a phenomenological model, is also fitted to the data to evaluate the validity of the gamma model.     

Preliminary Report on the Distribution of <Emphasis Type="Italic">Callicebus oenanthe</Emphasis> on the Eastern Feet of the Andes

In 2007 we conducted a field study of almost 6 mo to determine the distribution of Callicebus oenanthe, formerly known as the Andean titi monkey. There previously has been no extensive study on the distribution and status by other fieldworkers. We visited a total of 96 localities within or around the presumed distribution of this rare primate species to determine the distribution of Callicebus oenanthe. We collected additional information on group size and threats to the species. Our expeditions revealed that the species is not endemic to the Alto Mayo Valley, as earlier authors suggested, but that its distribution extends into the Bajo Mayo and Huallaga Central. The study area is heavily deforested, and to date only one area was found where a viable population might live, although further research is needed to confirm this. The species lives in the southern part of its distribution in sympatry with another, undescribed species of Callicebus. We will continue the study to determine more precisely the distribution and conservation status of the Callicebus oenanthe, to determine if conservation measures are necessary for this species. This is the first activity of a long-term project for the conservation of Callicebus oenanthe initiated by La Vallée des Singes Primate park.     

鲍曼不动杆菌VI型分泌系统功能蛋白的研究及应用新进展

细菌VI型分泌系统（type VI secretion system,T6SS）作为一个动态多蛋白复合体,各元件之间分工明确,转运各种效应蛋白作用于竞争细菌获得自我生长优势。鲍曼不动杆菌（Acinetobacter baumannii,Ab）通过T6SS介导细菌在微生物群落中的竞争能力,影响其耐药进化、宿主侵袭感染等过程。其中,缬氨酸-甘氨酸-精氨酸G蛋白三聚体（valine-glycine repeat protein G,VgrG）、脯氨酸-丙氨酸-丙氨酸-精氨酸重复序列蛋白（proline-alanine-alanine-arginine,PAAR）、溶血素共调节蛋白（hemolysin-coregulated protein,Hcp）和效应-免疫（effector-immunity,E-I）对发挥着关键作用。有关T6SS的研究总结虽然很多,但是鲜有文章系统概述其临床应用前景,因为这对T6SS功能蛋白的鉴定、特性、转运机制等基础研究的进展提出了挑战。本文通过综述鲍曼不动杆菌中T6SS的分布、主要功能蛋白的特性及转运机制的研究进展,结合T6SS的应用案例,提供其应用的可行性证据。以期进一步推动鲍曼不动杆菌VI型分泌系统基因和功能的研究,为开发新型抗感染疫苗、筛选合适的靶点抑制剂及生产工程化药物递送工具提供新的思路。     

Nicotinamide nucleotide transhydrogenase mRNA expression is related to human obesity

Objective:

A spontaneous deletion in the nicotinamide nucleotide transhydrogenase (Nnt) gene eliminating exons 7‐11 in C57BL/6J (B6J) mice is associated with reduced glucose‐stimulated insulin secretion in vitro, impaired glucose tolerance, higher epigonadal fat mass, and altered susceptibility to diet induced obesity of male B6J mice was proposed. A potential implication for NNT in human adipose tissue distribution has not been investigated so far.

Design and Methods:

Therefore, NNT mRNA expression in paired human samples of visceral (vis) and subcutaneous (sc) adipose tissue from 221 subjects with a wide range of body mass index (BMI), insulin sensitivity, and glucose tolerance was analyzed.

Results:

NNT mRNA expression is significantly higher in visceral fat of obese patients and correlates with body weight, BMI, % body fat, visceral and sc fat area, waist and hip circumference, and fasting plasma insulin (FPI). Multivariate linear regression analysis revealed visceral NNT expression as age and gender independent predictor of BMI, waist circumference, visceral fat area, and % body fat, but not FPI and 2 h OGTT glucose.

Conclusion:

In conclusion, a functional relevance of NNT in the development of human obesity and visceral fat distribution was suggested here.     

Excess of multifocal tumors in nephroblastoma: implications for mechanisms of tumor development and genetic counseling

Referring to the mutational theory of carcinogenesis in embryonal tumors, it is commonly accepted that patients with multifocal tumors are hereditary cases. This is based on the implicit assumption that each tumor results from a single mutational event occurring in a cell that has already inherited a mutation, and that these tumors are independent. We studied the distribution of tumors in 1,868 cases where the focality was known (SIOP 1, 2, 5 and 6). Using all the supposed gene carriers (bilateral and unilateral multifocal cases), and assuming a Poisson distribution of tumors, we estimated the mean number m of tumors in each kidney to be 0.37. Comparing the observed distribution of cases to the expected one, we found a very bad fit to this hypothesis (P<10^-9). This is due to an excess of multifocal tumors, particularly in unilateral cases. These findings have important implications in genetic counseling, since the usual practice of considering multifocal tumor patients as hereditary cases may result in a large overestimate of the recurrence risk in such cases. The implications for the mechanisms of tumor development are also discussed.     

Dynamic fluorescence of extrinsic fluorophores as a tool for studying protein conformational substates

Summary The fluorescence lifetime distribution of 2-p-toluidinyl-6-naphthalene sulfonic acids (TNS) bound to the heme site of apomyoglobin has been examined. The results were compared to those observed for the free fluorophore in isotropic nonviscous solvent. Two different excitation wavelengths were used, i.e. 290 and 350 nm. The results showed that the distribution of TNS bound to apomyoglobin is wider than that of the free fluorophore, thus indicating the existence of a large number of conformational substates originating from the interaction between TNS and the protein matrix. The comparison of the distribution obtained at two different excitation wavelengths allowed the emission arising from conformational substates, in which the excited state of fluorophore moiety has a higher probability to be populated by Forster energy transfer mechanism, to be distinguished.     

Bupleurum shanianum sp. nov. (Apiaceae) from China

Bupleurum shanianum X. G. Ma & X. J. He, previously recognized in China as B. gracillimum, is proposed here as a new species. This new species and B. gracillimum differ in many morphological characters (flowering stem position, bract size, number of flowers per umbellule) and have non‐overlapping distribution ranges. Bupleurum shanianum is most similar to B. yunnanense Franch., but the new species has shorter cauline leaves, and umbellules usually with 4 bracteoles and 3–6(–9) flowers. Bupleurum shanianum is known from eastern Himalayas to western Sichuan.     

The evolutionary history of SLC6A4 and the role of plasticity in macaca

Serotonin has been repeatedly indicated as a biological marker of behavior. In particular, the serotonin transporter gene, SLC6A4, has been the focus of a large body of research. Interestingly, both rhesus macaques (Macaca mulatta) and humans have independently evolved a number of shared polymorphisms for this gene, which is indicative of parallel evolution between the two species. However, little is known about the evolution of this gene, particularly within macaques. Although there are several hypotheses as to the adaptive values of various polymorphisms, few authors have gone beyond theoretical discussion. Here, we examined the genetic variation in SLC6A4 within and between several species of macaques and investigate whether selection has played a significant role in its evolutionary history. In addition, we assayed the promoter region polymorphism, 5‐HTTLPR, which is known to play a significant role in regulating both serotonin turnover and behavior. In examining the distribution of the 5‐HTTLPR polymorphism, we identified significant differences between Indian and Chinese populations of Macaca mulatta; furthermore, we discovered its presence in Macaca cyclopis, which has not been described before. In regard to the evolutionary history of SLC6A4, we found little evidence for selection and conclude that SLC6A4 largely evolved through neutral processes, possibly due to its potential role in regulating behavioral plasticity. However, we also found very low levels of linkage between the coding regions and 5‐HTTLPR. Because we limited evolutionary analyses to the coding regions, it is possible that the promoter region shows a distinct evolutionary history from SLC6A4. Am J Phys Anthropol 153:605–616, 2014. © 2013 Wiley Periodicals, Inc.     

Functional Analyses of Tyr420 and Leu607 of Alicyclobacillus acidocaldarius Squalene-Hopene Cyclase. Neoachillapentaene,a Novel Triterpene with the 1,5,6-Trimethylcyclohexene Moiety…

The functions of Tyr420 and Leu607 were analyzed by constructing various site-directed mutants. The mutation at position 420 into Ala and Gly gave bicyclic α- and γ-polypodatetraene in significant amounts, but with a trace amount of tricyclic malabaricatriene. The kinetic data for and the product distribution of the Y420F mutant indicate that the major function of Tyr420 is to stabilize the 6/6-fused bicyclic cation. Mutation experiments on Leu607 demonstrate that the appropriate steric bulk size at position 607 is required to strongly bind with the product-like conformation formed during the polycyclization process. Introduction of the bulkiest Trp residue into 420 or 607 led to the production of a novel monocyclic triterpene having the (5R,6R)-1,5,6-trimethylcyclohexene ring, named neoachillapentaene, indicating that the enzymatic cyclization proceeded via a constrained boat structure. Folding of the squalene molecule into a boat conformation by squalene cyclase has not been reported before.     

安徽省某酸性矿山废水坑湖中细菌群落的垂向分布特征及其影响因素

【目的】探究酸性矿山废水(acid mine drainage,AMD)坑湖中细菌群落沿垂向不同水深的分布规律及与环境因子之间的相互作用。【方法】采用16SrRNA基因高通量测序技术,对安徽省某AMD坑湖中6条采样垂线不同水深深度的细菌群落进行调查,同时测定水质理化指标,使用统计学软件分析细菌和地化参数间的联系。【结果】AMD坑湖中水质特征及细菌群落结构出现明显分层现象,自上而下溶解氧降低而pH和多种金属离子浓度增加,微生物群落结构发生变化,多样性和部分物种的丰度增大。细菌群落组成上,表层水域以Proteobacteria (Alpha、Gammaproteobacteria)和Acidobacteria占据主导地位;中下层水域则由Firmicutes、Acidobacteria、Actinobacteria、Gammaproteobacteria和Patescibacteria等共同主导。统计分析结果表明,TN、DO、ORP、pH、Fe、Mn、Al和Zn与嗜酸细菌丰度显著相关,是细菌空间分布的主要限制因素。【结论】AMD坑湖中水质理化特征和细菌群落分布在垂向空间上存在显著差异,群落的...     

Genetic Variation and Population Differentiation in Natural Populations of Cryptomeria japonica

Abstract Sugi (Cryptomeria japonica D. Don) is a valuable tree species in Japan. The present natural distribution is limited to small scattered areas in temperate moist regions, and most of these areas are surrounded by vast artificial plantations. We studied natural populations of C. japonica in an effort to determine the amount and distribution of genetic diversity using 12 allozyme markers. The amount of genetic variation within the species is high (H_T=0.196) but most is found within populations with little among populations (G_ST=0.034) despite their isolated distribution. This pattern of genetic diversity is inferred to be the consequence of the following: (1) the distribution of this species in the past was wider and more continuous than it is now; (2) a high rate of gene flow occurs, perhaps including gene flow between natural populations and plantations; and (3) the long lifespan. However, the distribution of allele frequencies at the 6Pg-1 in northern populations on the side near the Sea of Japan is clearly different from those in other populations. This observation is inferred to result from founding events.     

Esr,a second locus in the house mouse controlling esterase-5

Electrophoretic variation characterized by the presence (ES-5B⁺) or absence (ES-5B^–) of esterase-5B in the plasma of the house mouse has been observed. It is suggested that the expression of esterase-5B is controlled by an autosomal locus, Esr, linked to Ldr-1 on chromosome 6, in addition to the presumptive structural locus Es-5, which is located on chromosome 8. A gene order of Lyt-3-Esr-Ldr-1 was determined by two crosses.Supported by the Deutsche Forschungsgemeinschaft (SFB 46).This is communication No. 33 of a research program devoted to the investigation of cellular distribution and genetics of nonspecific esterases.     

Biogeographic analysis of the Uhu and LOA elements in the Hawaiian Drosophila

Two transposable elements have been isolated from the Hawaiian Drosophila, the Uhu and LOA elements. The Uhu element has been shown to be present in a group of closely related species, the planitibia subgroup of the picture-winged Drosophila. This study examines the distribution of the Uhu element in several other subgroups of the picture-winged Drosophila, as well as the modified-mouthparts and antopocerus groups of the Hawaiian Drosophila. The LOA element has a much more limited distribution, having only been found in representatives of the planitibia and grimshawi subgroups of the picture-winged Drosophila. For both the Uhu and LOA elements there is an inverse correlation between the copy number of the element and the age of the island on which the species is endemic, i.e., species endemic to the Island of Hawaii, the youngest island, have the highest copy number, while species endemic to Kauai, the oldest island, have the lowest copy number of the element. The correlation suggests there is a relationship between speciation and the activity of transposable elements. Received: 6 January 1997; in revised form: 6 August 1997 / Accepted: 21 August 1997     

Monitoring of the Membrane Potential in Proteoliposomes with Incorporated Cytochrome-c Oxidase Using the Fluorescent Dye Indocyanine

A method has been developed to monitor changes of the membrane potential across vesicle membranes in real time. Using the potential-sensitive fluorescent dye indocyanine and on the basis of a water/lipid redistribution model, a calculation procedure has been introduced to estimate the membrane potential in vesicles with incorporated cytochrome-c oxidase. Physical parameters, such as vesicle size distribution and density of the lipid bilayer were estimated and used as calculation parameters. By extrapolation of the transient potential change to zero time, the initial rate of the potential change (dU/dt) could be calculated. It is also shown, that the initial potential change (dU/dt) may be used to study the proton/electron stoichiometry of cytochrome-c oxidase incorporated in the vesicles. Received: 28 September 1995/Revised: 6 February 1996     

Distribution of the species of rough periwinkle (Littorina) in Great Britain

The status of the four currently recognised species in the Littorina saxatilis species-complex, i.e. Littorina nigrolineata Gray, L. arcana Hannaford Ellis, L. saxatilis (Olivi) and L. neglecta Bean is reviewed briefly, with notes on their characteristic features and location on the shore. Since the taxonomy of these rough periwinkles has only become stable relatively recently much of the previously published information on distribution is of little or no use. In this paper their distribution around the coastline of England and Wales (with some notes on Scotland) is described and discussed. L. saxatilis is found in a wide range of habitats from exposed peninsulas to estuaries on all shores where there is a suitable rocky or stony substrate; also in salt marsh pools. L. arcana has a more restricted distribution and is notably absent along much of the south English coast, central Cardigan Bay and possibly northern Scotland; it is not found in estuaries. L. nigrolineata has an even more restricted distribution, although it occurs both on exposed coasts and in estuaries; it has only been found by us in one locality on the east coast. L. neglecta is probably fairly widely distributed but we have few details so far. The implications of the different patterns of distribution are discussed.