我国西南部喀斯特森林特有濒危树种掌叶木新的微卫星分子标记的开发

采用基因组DNA富集文库法FIASCO(Fast isolation by AFLP of sequences containing repeats)从掌叶木(Handeliodendron bodinieri)基因组中分离和筛选了10个新的微卫星位点,进而对掌叶木茂兰自然分布居群的遗传多样性进行了分析。结果表明, 每个位点在30株掌叶木个体上的平均等位基因数(A)为3.5(3~5个),平均观察杂合度(H_O)为0.650(0.267~0.900),平均预期杂合度(H_E)为0.494(0.224~0.652)。每个位点的第一排除概率值P_r(Ex₁)为0.029~0.240,位点综合值为0.7496。单个位点的第二排除概率P_r(Ex₂)为0.123~0.419,位点综合值为0.9517。这些信息预示着这些微卫星标记可以为研究喀斯特特有濒危树种掌叶木的基因流及居群遗传结构提供有效的遗传工具。     

Antimicrobial susceptibility and genetic relatedness of bovine Stenotrophomonas maltophilia isolates from a mastitis outbreak

Aims: To evaluate the antimicrobial susceptibility and genetic relatedness of 11 Stenotrophomonas maltophilia isolates from an outbreak of bovine clinical mastitis in one herd and two isolates from two separate mastitis cases in two other herds. Methods and Results: Thirteen S. maltophilia isolates were obtained from milk samples from 11 cows from three dairy herds in Japan during 2008. We tested their susceptibility to 14 antimicrobials by broth microdilution and identified their genotypes by enterobacterial repetitive intergenic consensus 2 (ERIC2)‐PCR. Every cow had acute mild mastitis (slightly watery foremilk with flakes) without systemic symptoms and all resolved within 3–5 weeks of diagnosis. Eleven of the 13 isolates derived from nine cows in one herd over a 7‐month period exhibited a closely related ERIC2 type (A). The remaining two isolates derived from two cows from two other herds exhibited two distinct ERIC2 types (B and C). Most of the 13 isolates exhibited susceptibility to trimethoprim‐sulfamethoxazole, chloramphenicol, minocycline and levofloxacin; however, they were resistant to four β‐lactams, kanamycin, gentamicin and oxytetracycline. They were intermediate to enrofloxacin. Conclusions: Eleven closely related S. maltophilia isolates were involved in a herd outbreak of mastitis to some extent. Bovine S. maltophilia isolates exhibited resistance to many classes of antimicrobials. Significance and impact of study: This is a rare report of a herd outbreak of bovine mastitis involving closely related S. maltophilia isolates.     

A declarative constraint-based method for analyzing discrete genetic regulatory networks

Dynamical modeling has proven useful for understanding how complex biological processes emerge from the many components and interactions composing genetic regulatory networks (GRNs). However, the development of models is hampered by large uncertainties in both the network structure and parameter values. To remedy this problem, the models are usually developed through an iterative process based on numerous simulations, confronting model predictions with experimental data and refining the model structure and/or parameter values to repair the inconsistencies. In this paper, we propose an alternative to this generate-and-test approach. We present a four-step method for the systematic construction and analysis of discrete models of GRNs by means of a declarative approach. Instead of instantiating the models as in classical modeling approaches, the biological knowledge on the network structure and its dynamics is formulated in the form of constraints. The compatibility of the network structure with the constraints is queried and in case of inconsistencies, some constraints are relaxed. Common properties of the consistent models are then analyzed by means of dedicated languages. Two such languages are introduced in the paper. Removing questionable constraints or adding interesting ones allows to further analyze the models. This approach allows to identify the best experiments to be carried out, in order to discriminate sets of consistent models and refine our knowledge on the system functioning. We test the feasibility of our approach, by applying it to the re-examination of a model describing the nutritional stress response in the bacterium Escherichia coli.     

利用SRAP标记分析河南小麦栽培品种的遗传多样性

利用小麦SRAP标记对22个河南省小麦品种进行了遗传多样性分析,10对引物组合扩增获得169个条带,其中70个条带具有多态性,多态条带百分率为41．42％,每对引物平均产生7个多态性条带。22个供试材料的带型按照条带的有、无分别记录为1、0后,采用Nei72方法计算不同品种的遗传距离,利用NTSYS软件进行非加权组法（UPGMA）聚类分析。结果表明SRAP标记技术能较真实地反映小麦品种间的亲缘关系,可以用于小麦品种遗传多样性研究。     

Genetic variation in nine Shorea species (Dipterocarpaceae) in Indonesia revealed by AFLPs

Shorea is the largest and most important genus of the Dipterocarpaceae. The genetic diversity and structure of nine Shorea species from two different locations, namely Nanjak Makmur in Sumatra and Sumalindo in Borneo, were evaluated using amplified fragment length polymorphism (AFLP) markers. A total of 274 trees were investigated at 85 polymorphic AFLP loci. Levels of genetic diversity of these species ranged from  = 0.100 for S. acuminata to  = 0.165 for S. blumutensis. The population of rare species S. blumutensis possessed the highest genetic diversity suggesting that geographically restricted species can have levels of genetic variation comparable to closely related widespread common congeners. Analyses of molecular variance revealed that the genetic variation was mainly found among species in both locations (57.7% in Sumatra; 56.3% in Borneo). The unweighted pairgroup method using arithmetic averages dendrogram of all samples revealed an almost complete separation of species. Thus, AFLP markers proved appropriate for phylogenetic studies of Shorea species. Specific markers have been detected showing high-frequency differences among species and between regions within species. Sequence information of these markers can be used to develop specific polymerase chain reaction markers for wood identification. The possibility of interspecific hybridization was discussed.     

Genetic selection for a highly functional cysteine-less membrane protein using site saturation mutagenesis

We describe an efficient method for generating highly functional membrane proteins with variant amino acids at defined positions that couples a modified site saturation strategy with functional genetic selection. We applied this method to the production of a cysteine-less variant of the Crithidia fasciculata inosine-guanosine permease CfNT2 to facilitate biochemical studies using thiol-specific modifying reagents. Of 10 endogenous cysteine residues in CfNT2, two cannot be replaced with serine or alanine without loss of function. High-quality single- and double-mutant libraries were produced by combining a previously reported site saturation mutagenesis scheme based on the Stratagene Quikchange method with a novel gel purification step that effectively eliminated template DNA from the products. Following selection for functional complementation in Saccharomyces cerevisiae cells auxotrophic for purines, several highly functional noncysteine substitutions were efficiently identified at each desired position, allowing the construction of cysteine-less variants of CfNT2 that retained wild-type affinity for inosine. This combination of an improved site saturation mutagenesis technique and positive genetic selection provides a simple and efficient means to identify functional and perhaps unexpected amino acid variants at a desired position.     

Genetic diversity and biogeography of the traditional Chinese medicine, Gardenia jasminoides, based on AFLP markers

Gardenia jasminoides Ellis is used in traditional Chinese medicine (TCM) in China. Levels of genetic variation and patterns of population structure within and among eight wild or cultivated populations of G. jasminoides Ellis in China were investigated using amplified fragment length polymorphism (AFLP) markers. Of the 11 primers screened, four produced highly reproducible AFLP bands. Using these primers, 244 discernible DNA fragments were generated with 165 bands (67.6%), were polymorphic, indicating considerable genetic variation at the species level. In contrast, there were relatively low levels of polymorphism at the population level with the percentage of polymorphic bands (PPB) ranging from 36.89% to 59.43%. Genetic diversity within populations ranged from 0.2086 to 0.3108, averaging 0.2392 at the species level. A high level of genetic differentiation among populations was detected based on Nei's genetic diversity analysis (76.59%), Shannon's index analysis (64.8%) and AMOVA analysis (72.75%). No significant statistical differences (analysis of molecular variance [AMOVA], p = 0.0639) in AFLP variation were found between regions. However, the variance among populations and within populations differed significantly (p < 0.001). An indirect estimate of historical levels of gene flow (N_m = 1.7448) was consistent with the high mean genetic identity (mean I = 0.9263) found among populations. There is an association between geographic and genetic distances between populations. Presently gene change exists between populations.     

蚕豆主要数量性状的遗传主成份和数量分类

对50个蚕豆品种的7个数量性状进行了遗传主成份分析, 初步提出了评选蚕豆品种的遗传主成份标准,并筛选出18个综合性状优良的亲本品种。测定了50个蚕豆品种的遗传距离, 根据遗传距离大小,将50个蚕豆品种聚类为2群、 3类、9组。分类结果指出,蚕豆品种的遗传距离大小与地理差异有些似有一定关系,但在总体上,二者间无必然联系。 Abastract:Analysis of major Genetic component analysis was performed for 7 quantitative characters of 50 faba bean lines and according to the analysis,18 lines were selected as parents.The 50 lines were classified into 2 subpopulations,3 types and 9 groups according to their genetic distance.The results showed that there was seemly a correlation between geographical distribution and genetic distance,nevertheless most lines within the same cluster were close in genetic distance but far in geographic sites.     

Multivariate analysis applied to tomato hybrid production

Summary Twenty characters were measured on 60 tomato varieties cultivated in the open-air and in polyethylene plastic-house. Data were analyzed by means of principal components, factorial discriminant methods, Mahalanobis D² distances and principal coordinate techniques. Factorial discriminant and Mahalanobis D² distances methods, both of which require collecting data plant by plant, lead to similar conclusions as the principal components method that only requires taking data by plots. Characters that make up the principal components in both environments studied are the same, although the relative importance of each one of them varies within the principal components. By combining information supplied by multivariate analysis with the inheritance mode of characters, crossings among cultivars can be experimented with that will produce heterotic hybrids showing characters within previously established limits.     

A new group-selection model for the evolution of homosexuality

Abstract. Scientists have long puzzled over how homosexual orientation has evolved, given the assumed low relative fitness of homosexual individuals compared to heterosexual individuals. A number of theoretical models for the evolution of homosexuality have been postulated including balance polymorphism, "Fertile females", hypervariability of DNA sequences, kin selection, and "parental manipulation". In this paper, I propose a new group-selection model for the evolution of homosexuality which offers two advantages over existing models: (1) its non-assumption of genetic determinism, and (2) its lack of dependency on an inefficient altruism relation and family dynamics theory.