Female reproduction bears no survival cost in captivity for gray mouse lemurs

The survival cost of reproduction has been revealed in many free‐ranging vertebrates. However, recent studies on captive populations failed to detect this cost. Theoretically, this lack of survival/reproduction trade‐off is expected when resources are not limiting, but these studies may have failed to detect the cost, as they may not have fully accounted for potential confounding effects, in particular interindividual heterogeneity. Here, we investigated the effects of current and past reproductive effort on later survival in captive females of a small primate, the gray mouse lemur. Survival analyses showed no cost of reproduction in females; and the pattern was even in the opposite direction: the higher the reproductive effort, the higher the chances of survival until the next reproductive event. These conclusions hold even while accounting for interindividual heterogeneity. In agreement with aforementioned studies on captive vertebrates, these results remind us that reproduction is expected to be traded against body maintenance and the survival prospect only when resources are so limiting that they induce an allocation trade‐off. Thus, the cost of reproduction has a major extrinsic component driven by environmental conditions.     

Accounting for heterogeneity when estimating stopover duration,timing and population size of red knots along the Luannan Coast of Bohai Bay,China

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Single-Cell Heterogeneity Analysis and CRISPR Screen Identify Key β-Cell-Specific Disease Genes

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Population genetics of <Emphasis Type="Italic">Collisella subrugosa</Emphasis> (Patellogastropoda: Acmaeidae): evidence of two scales of population structure

Marine invertebrate populations usually show high levels of genetic variability that has frequently been associated with spatial and temporal environmental heterogeneity. One of the most heterogeneous marine environments is the intertidal zone, the habitat of Collisella subrugosa, the most widespread and abundant Brazilian limpet. C. subrugosa has planktonic larvae that can disperse over long distances, what can promote gene flow among shores, working against interpopulational differentiation. In this study we investigated the genetic variability and populational substructure of C. subrugosa through analysis of 24 allozyme loci in 14 samples (590 individuals) collected along 2,700 km of the Brazilian coast. The genetic variability was high ( and ), as expected for intertidal species. Genetic differentiation among samples was low (F _ST = 0.03) what may reflect intensive gene flow associated with larval dispersal. However, we detected an isolation-by-distance pattern of population substructure in one sampled region. High levels of heterozygote deficiency were also observed for many loci in each sample. Alternative hypothesis are discussed, and the “breeding groups” is suggested to explain these pattern, indicating the main cause as environmental heterogeneity.     

Plant genomic DNA isolation: an art or a science

Isolating quality DNA from tissues/cells presents a variety of problems in particular when plants are used as the source material. The specific characteristics of plants like the presence of rigid polysaccharide cell wall, pigments, chemical heterogeneity of secondary metabolites found in diverse species of plants, etc., necessitate special consideration and skill during isolation procedure. Until now, numerous protocols have been published for the purpose, but none is found to be universally applicable. Various factors starting from the selection of source material to the concentration of metabolites present in the plant decide the course of the isolation procedure. The present review is an update of various methods used for plant genomic DNA isolation, and it epitomizes the various problems faced and the solutions made to contend with them during DNA isolation from plant cells.     

Effect of physiological heterogeneity of E. coli popula-tion on antibiotic susceptivity test

According to the instantaneous growth rate (dN/dt) of E. coli CVCC249 growing in batch culture, the entire growth progress was distinguished into four phases: accelerating growth phase, constant growth phase, decelerating growth phase and declining phase, in each of which obvious variation in physiological and biochemical properties was detected, including total DNA, total protein, and MTT-dehydrogenase activity, etc., that led to difference in their antibiotic susceptivity. Antibiotic susceptivity of the population sampled from each phase was tested by Concentration-killing Curve (CKC) approach following the formula N=N ₀/{1+exp[r·(x-BC ₅₀)]}, showing as normal distribution at the individual cell level for an internal population, in which the median bactericidal concentration BC ₅₀ represents the mean level of susceptivity, while the bactericidal span BC ₁₋₉₉=(2lnN ₀)/r indicates the variation degree of the antibiotic susceptivity. Furthermore, tested by CKC approach, the antibiotic susceptivity of E. coli CVCC249 population in each physiological phase to gentamicin or enoxacin was various: susceptivity of the population in the constant growth phase and declining phase all increased compared with that in the accelerating growth phase for gentamicin but declined for enoxacin. The primary investigations revealed that the physiological phase should be taken into account in the context of antibiotic susceptivity and research into antimicrobial mechanism. However there are few reports concerned with this study. Further research using different kinds of antibiotics with synchronized continuous culture of different bacterial strains is required. Supported by the Natural Science Foundation of Shandong Province, China (Grant No. Y2005C58), the Natural Key Technology R&D Program of China (Grant No. 2006BAK02A03-6) and the Youth Scientific Research Foundation of Shandong Academy of Agricultural Science (2005YQ035)     

Heterogenecity of stromal cell precursers isolated from rat bone marrow

Bone marrow stroma contains mesenchymal stem cells (MSC) which are progenitor cells, at least for tissues arising from mesechyma. The study of MSC biology yields controversial data. Therefore further experiments are needed to characterize these cells. The aim of our research was to compare primary cultures and subcultures of stromal precursor cells isolated from rat bone marrow. Long-term cultures of these cells isolated from 5 animals have been obtained. Morphological, immunophenotypic, and functional (capacity to osteogenic differentiation) characteristics of the cells have been investigated. We show that the cell morphology in the cultures is highly heterogenic. Morphological cell types are described. Heterogeneity of stromal cells declines on late passages. Cell cultures isolated from different animals have the same immunophenotypic markers (CD90, CD44, CD54, CD106, CD45, CD11b) but different morphological characteristics and a different capacity to osteogenic differentiation during long-term cultivation. The data show that more specific markers and functional tests should be applied to identify MSC.     

Amaranth Globulin Polypeptide Heterogeneity

The polypeptides integrating amaranth globulin-p and 11S-globulin were characterized by two-dimensional electrophoresis, ion-exchange chromatography and RP-HPLC. All polypeptides exhibited charge and hydrophobic heterogeneity. Almost all acid (A, pI 5–7) and basic (B, pI 9–10) polypeptides were present in both globulins, and the same happened with the unprocessed M polypeptides with pI in the range of 7–7.5 which fits well with a sequence containing both the A and B polypeptides. There were other polypeptides only present in 11S-globulin, like some of 41 and 16 kDa, which might come from another precursor or be the products of a different processing of the propolypeptide. These results suggested that, although amaranth subunits from different subfamilies are interchangeable in different oligomers, some structural differences between them might affect the assembly of globulin molecules. Structural differences arising from this behavior could account for the different physicochemical properties of globulin molecules.     

秦岭皇冠优势灌木苦糖果的空间分布格局及种内种间关联

以秦岭皇冠暖温性落叶阔叶林25 hm²森林样地中的优势灌木苦糖果为对象,研究了苦糖果不同径级个体的空间分布格局以及种内种间关系。结果表明: 苦糖果径级结构呈现出下宽上窄的金字塔型,小径级植株数量最多,更新状态较好,处于稳定增长阶段,有利于群落更新和演替。以Ripley's K函数为基础,采用单变量和双变量成对相关函数,在3个零模型(完全空间随机模型、异质泊松模型和先决条件模型)的处理下,树种整体和不同径级以聚集分布为主,且聚集程度随研究尺度的加大而逐渐减小,逐渐趋向随机分布。受到生境异质性、扩散限制、负密度制约等影响,种内不同径级个体之间以正关联为主,但也有一定程度的无关联,未出现负关联的情况。种间关系较为复杂,既有无关联,也有正关联和负关联,但以负关联和无关联为主。