A genetic linkage map of Picea abies Karst., based on RAPD markers,as a tool in population genetics

Norway spruce (Picea abies Karst.) is a most important species among European forest trees for both economical and ecological reasons. However, this species has suffered from a lack of information on the genetic side due to the scarcity of linkage data. In this study we have used a population of 72 megagametophytes from a single tree in a natural Italian stand to produce a genetic linkage map by means of RAPD markers. Ninety-six random decamers used as primers yielded 185 polymorphic loci showing Mendelian inheritance. Analysis of the segregation by multipoint analysis allowed us to define 17 major linkage groups covering a total distance of 3584 cM, with an average spacing between markers of 22 cM. Possible uses of a genetic linkage map with respect to population ecology and genetics are discussed.     

环境因子对荒漠沙蜥种群密度影响的研究

本文研究人类改造荒漠的活动,植被,潜在的可利用的食物资源,竞争种的密度,土壤理化性质等坏境因子对荒漠沙蜥种群密度的影响。结果说明：人类的活动对沙蜥种群密度没有显著影响;决定沙蜥种群密度的主导因子是潜在的可利用的食物资源,植被,土壤含水量,竞争种的密度。这些因子的任何改变都能改变沙蜥的种群密度,均具有调节种群的作用。     

A deterministic analysis of self-incompatibility alleles

A number of plant species have a self-incompatibility locus that prevents self-fertilization. We 'analyse a deterministic model with an arbitrary number of alleles. We prove that the only polymorphic equilibrium is the one for which all (heterozygous) genotypes are equally frequent, and we prove that all (initially) polymorphic populations converge to this equilibrium.     

The effect of salinity on the reproduction of coastal submerged macrophytes in experimental communities

The effects of salinity on the reproduction of coastal submerged macrophyte species were studied on samples of communities from six seasonal marshes in two outdoor experiments performed in autumn and in spring. The submerged macrophyte communities were submitted to five different salinity levels (0, 1, 2, 4 and 6 g/1 Cl^?1). In a companion paper (Grillas, van Wijck & Bonis 1993) three groups of species were distinguished on the basis of their biomass production over the salinity range 0 to 6 g/1 Cl^?1: (1) glycophytes (non-salt-tolerant species), (2) salt-tolerant species and (3) halo-phytes. This part of the study describes the impact of salinity on the reproduction of the individual species during the two experiments. The species differ in their capacity to reproduce in the autumn; only Zannichelliapedunculata and Tolypella hispánica were able to produce fruits in that season. For all species reproduction was greater in spring and strongly correlated with biomass, except for Chara canescens. Differences in reproductive effort over the salinity range amplified the halophytic nature of Ruppia marítima and Chara canescens and the intolerance of Callitriche truncata and Chara contraria. For the other species, reproductive effort did not differ significantly over the salinity range. Regarding the effect of salinity on biomass and reproductive effort of individual species, there were large differences in the total weight of propagules produced at the community level and in the relative contribution of individual species. The resulting quantitative changes in the species composition of the seed bank could affect the structure of the communities by their effects on the establishment and survival of species populations.     

A genome-wide perspective on the diversity and selection signatures in indigenous goats using 53 K single nucleotide polymorphism array

Tibetan goats, Taihang goats, Jining grey goats, and Meigu goats are the representative indigenous goats in China, found in Qinghai-Tibet Plateau, Western pastoral area, Northern and Southern agricultural regions. Very few studies have conducted a comprehensive analysis of the genomic diversity and selection of these breeds. We genotyped 96 unrelated individuals, using goat 53 K Illumina BeadChip array, of the following goat breeds: Tibetan (TG), Taihang (THG), Jining grey (JGG), and Meigu (MGG). A total of 45 951 single nucleotide polymorphisms were filtered to estimate the genetic diversity and selection signatures. All breeds had a high proportion (over 95%) of polymorphic loci. The observed and excepted heterozygosity ranged from 0.338 (MGG) to 0.402 (JGG) and 0.339 (MGG) to 0.395 (JGG), respectively. Clustering analysis displayed a genetically distinct lineage for each breed, and their Fst were greater than 0.25, indicating that they had a higher genetic differentiation between groups. Furthermore, effective population size reduced in all four populations, indicating a loss of genetic diversity. In addition, runs of homozygosity were mainly distributed in 5–10 Mb. Lastly, we identified signature genes, which were closely related to high-altitude adaptation (ADIRF) and prolificity (CNTROB, SMC3, and PTEN). This study provides a valuable resource for future studies on genome-wide perspectives on the diversity and selection signatures of Chinese indigenous goats.     

Mathematical simulation of the interactions among cyanobacteria, purple sulfur bacteria and chemotrophic sulfur bacteria in microbial mat communities

Abstract: A deterministic one-dimensional reaction diffusion model was constructed to simulate benthic stratification patterns and population dynamics of cyanobacteria, purple and colorless sulfur bacteria as found in marine microbial mats. The model involves the major biogeochemical processes of the sulfur cycle and includes growth metabolism and their kinetic parameters as described from laboratory experimentation. Hence, the metabolic production and consumption processes are coupled to population growth. The model is used to calculate benthic oxygen, sulfide and light profiles and to infer spatial relationships and interactions among the different populations. Furthermore, the model is used to explore the effect of different abiotic and biotic environmental parameters on the community structure. A strikingly clear pattern emerged of the interaction between purple and colorless sulfur bacteria: either colorless sulfur bacteria dominate or a coexistence is found of colorless and purple sulfur bacteria. The model predicts that purple sulfur bacteria only proliferate when the studied environmental parameters surpass well-defined threshold levels. However, once the appropriate conditions do occur, the purple sulfur bacteria are extremely successful as their biomass outweighs that of colorless sulfur bacteria by a factor of up to 17. The typical stratification pattern predicted closely resembles the often described bilayer communities which comprise a layer of purple sulfur bacteria below a cyanobacterial top-layer; colorless sulfur bacteria are predicted to sandwich in between both layers. The profiles of oxygen and sulfide shift on a diel basis similarly as observed in real systems.     

布氏田鼠肥满度分析和小型兽类肥满度指标K与KWL（重长指标）的比较

通过对两个肥满度指标的理论和生物学意义分析,以及对布氏田鼠肥满度的研究和实际应用的讨论,认为描述动物的肥满度时,重长指标ＫＷＬ优于指标Ｋ。两指标的最大差别是成体的ＫＷＬ值大于幼体,而成体的Ｋ值小于幼体。布氏田鼠肥满度没有性别差异;有异著的年龄差异,成体鼠的肥满度高于幼鼠;有显著的季节变化,鼠种群春季肥满度最高,夏季降低,秋季回升;有显著的年际变化,高数量年的肥满度高于低数量年。     

Variability of genetic serum protein markers in Austria

Haptoglobin (HP), transferrin (TF), group specific component (GC) and protease inhibitor (PI) polymorphisms were studied in a population sample (n=272) from Tyrol (Austria). Comparing the allele frequencies of these polymorphic serum protein systems with those reported on other Austrian population samples some heterogeneity in the regional distribution of allele frequencies was seen, especially concerning the GC system. The reasons for that may be due to different historical backgrounds in the various regions of Austria.     

Triton X-100 alters the resistance level of methicillin-resistant Staphylococcus aureus to oxacillin

Abstract We used population analysis to examine the effects of Triton X-100 on the level of resistance to oxacillin of 18 methicillin-resistant Staphylococcus aureus . In the presence of 0.02% Triton X-100, 17 formerly methicillin-resistiant strains exhibited enhanced sensitivity to oxacillin. One homogeneous isolate, KSAF1 was barely affected by the Triton X-100. Sensitivities of lysostaphin, 51 kDa N -acetylglucosaminidase and 62 kDa N -acetylmuramoyl-l-alanine amidase to heat-inactivated cells were not affected when the bacteria were grown in 0.02% Triton X-100. Our data, together with those of a previous study, suggested that Triton X-100 alters the resistance level of methicillin-resistant S. aureus by influencing a factor(s) other than PBPs, bacteriolytic enzymes, or femAB products.