Associations between common variation in the aromatase gene promoter region and testosterone concentrations in two young female populations

We recently reported association between a coding-region single nucleotide polymorphism (SNP50) in the aromatase gene that encodes a key enzyme in testosterone metabolism, with risk for the development of precocious pubarche and circulating testosterone concentrations in two independent female populations. We have now explored further association with variation in the promoter-region of the aromatase gene. We genotyped six promoter-region haplotype-tag SNPs in young women from Oxford, UK (n = 109), and in girls with precocious pubarche (n = 186) and controls (n = 71) from Barcelona, Spain. Aromatase distal promoter-region variation was associated with plasma testosterone concentrations in both Oxford (r² = 18.3%, p = 0.01) and Barcelona (r² = 8.5%, p = 0.03) females. These associations were independent of SNP50, but appeared to be dependent on different SNPs in Oxford (r² = 13.7%, p = 0.006 with SNPs 11 (p = 0.009), 28 (p = 0.02) and 39 (p = 0.06)) and Barcelona (r² = 5.9%, p = 0.002 with SNP43 (p = 0.002)) populations. Aromatase distal promoter-region variation was also associated with PCOS symptom score in Oxford women (r² = 14.5%, p = 0.048), but, unlike SNP50, was not associated with precocious pubarche risk in Barcelona girls. In conclusion, aromatase distal promoter-region variation appears to have functional consequences for plasma testosterone concentrations in females. The variable associations with androgen-related clinical features could possibly reflect the tissue-specific promoters of the aromatase gene.     

Identification of candidate genes and mutations in QTL regions for immune responses in chicken

There are two categories of immune responses – innate and adaptive immunity – both having polygenic backgrounds and a significant environmental component. In our study, adaptive immunity was represented by the specific antibody response toward keyhole limpet hemocyanin (KLH); innate immunity was represented by natural antibodies toward lipopolysaccharide (LPS) and lipoteichoic acid (LTA). Defining genetic bases of immune responses leads from defining quantitative trait loci (QTL) toward a single mutation responsible for variation in the phenotypic trait. The goal of the reported study was to define candidate genes and mutations for the immune traits of interest in chicken by performing an association study of SNPs located in candidate genes defined in QTL regions. Candidate genes and SNPs in QTL regions were selected in silico. SNP association was based on a custom SNP panel, GoldenGate genotyping assay (Illumina) and two statistical models: random mixed model and CAR score. The most significant SNP for immune response toward KLH was located in the JMJD6 gene located on GGA18. Four SNPs in candidate genes FOXJ1 (GGA18), EPHB1 (GGA9), PTGER4 (GGAZ) and PRKCB (GGA14) showed association with natural antibodies for LPS. A single SNP in ITGB4 (GGA18) was associated with natural antibodies for LTA. All associated SNPs mentioned above showed additive effects.     

Contribution to the knowledge of Bulgarian serpentine grasslands and their relationships with Balkan serpentine syntaxa

Serpentine areas, including those in Bulgaria, are rich in endemic taxa, and still remain to be investigated phytocoenologically. We analyse the vegetation types in various sites and compare them with those in other Balkan countries. The main objectives were (1) to explore and describe the relationships between the vegetation in the serpentine areas investigated in Bulgaria with those in the Balkan Peninsula and (2) to explore and classify the diversity of vegetation in grasslands on serpentine rocks in eastern Rhodope, Bulgaria. The classic methodology of the Braun-Blanquet school was applied to the exploration of the vegetation. Average linkage method (unweighted pair group method with arithmetic mean) and principal coordinate analysis were used to evaluate floristic and synoptic similarities. As a result, the new endemic association Onosmo pavlovae-Festucetum dalmaticae was proposed. This association can be included in the alliance Alyssion heldreichii Bergmeier et al. 2009, newly described on serpentine rocks in northern Greece. Our data confirmed the existence of similar or vicariant endemic syntaxa (associations) on isolated serpentine terrains in northern Greece and south-eastern Bulgaria.     

Expression patterns and association analysis of the porcine DHX58 gene

RIG-1 signalling is responsible for the detection of cytoplasmic viral RNA molecules. DEXH (Asp-Glu-X-His) box polypeptide 58 (encoded by DHX58) is a negative regulator of the RIG-1 signalling pathway. In human, the DHX58 gene can be upregulated and can inhibit the RIG-1 signalling pathway during viral infection. In this study, porcine DHX58 gene expression patterns were studied. According to our results, the porcine DHX58 gene was upregulated not only by the stimulation of Poly I:C but also by the stimulation of 1ipopolysaccharides (LPS). One polymorphism (g.4919G>C), detected in the ninth intron, was significantly associated with some blood parameters including the red cell distribution width of 1-day-old pigs and white blood cell counts, lymphocyte absolute counts, and platelet distribution width of 17-day-old pigs (P < 0.05). Moreover, the individuals with the genotype GG have a significantly higher mean white blood cell count than individuals with genotype CC or GC (P < 0.05). Our study indicates that DHX58 is an important gene that is associated with the immune response in swine.     

Non-aceticlastic methanogenesis from acetate: acetate oxidation by a thermophilic syntrophic coculture

Methanogenesis from acetate by a rod-shaped enrichment culture grown at 60° C was found to require the presence of two organisms rather than a single aceticlastic methanogen. A thermophilic Methanobacterium which grew on H₂/CO₂ or formate was isolated from the enrichment. Lawns of this methanogen were used to co-isolate an acetate oxidizer in roll tubes containing acetate agar. The rod-shaped acetate oxidizer was morphologically distinct from the methanogen and did not show F₄₂₀ autofluorescence. The coculture completely degraded 40 mol/ml acetate, and produced nearly equal quantities of methane, and methanogenesis was coupled with growth. The doubling time for the coculture at 60°C was 30–40 h and the yield was 2.7±0.3 g dry wt/mol CH₄. Studies with ¹⁴C-labelled substrates showed that the methyl group and the carboxyl group of acetate were both converted primarily to CO₂ by the coculture and that CO₂ was concurrently reduced to CH₄. During growth, there was significant isotopic exchange between CO₂ and acetate, especially with thecarboxyl position of acetate. These results support a mechanism for methanogenesis from acetate by the coculture in which acetate was oxidized to CO₂ and H₂ by one organism, while H₂ was subsequently used by a second organism to reduce CO₂ to CH₄. Since the H₂ partial pressure must be maintained below 10^-4 atm by the methanogen for acetate oxidation to be thermodynamically feasible, this is an example of obligate interspecies hydrogen transfer. This mechanism was originally proposed for a single organism by Barker in 1936.     

Genetic risk variants for dyslexia on chromosome 18 in a German cohort

Dyslexia is characterized by impaired reading and spelling. The disorder has a prevalence of about 5% in Germany, and a strong hereditary component. Several loci are thought to be involved in the development of dyslexia. Scerri et al. identified eight potential dyslexia‐associated single nucleotide polymorphisms (SNPs) in seven genes on chromosome 18 in an English‐speaking population. Here, we present an association analysis that explores the relevance of these SNPs in a German population comprising 388 dyslexia cases and 364 control cases. In case–control analysis, three nominal SNP associations were replicated. The major alleles of NEDD4L‐rs12606138 and NEDD4L‐rs8094327 were risk associated [odds ratio (OR) = 1.35, 95% confidence interval (CI) = 1.0–1.7, P‐value = 0.017 and OR = 1.39, 95% CI = 1.1–1.7, P‐value = 0.007, respectively], and both SNPs were in strong linkage disequilibrium (r² = 0.95). For MYO5B‐rs555879, the minor allele was risk associated (OR = 1.31, 95% CI = 1.1–1.6, P‐value = 0.011). The combined analysis of SNP sets using set enrichment analysis revealed a study‐wide significant association for three SNPs with susceptibility for dyslexia. In summary, our results substantiate genetic markers in NEDD4L and MYO5B as risk factors for dyslexia and provide first evidence that the relevance of these markers is not restricted to the English language .     

三峡大坝下游残存疏花水柏枝种群结构和动态

在三峡大坝下游的湖北宜都关洲设立1个40 m×40 m的固定样地,利用高度分级,比较2008与2009年两年间的疏花水柏枝（Myricaria laxiflora）种群数量动态,并运用点格局的Ripley＇s K函数分析了其空间格局变化及种群更新特征。结果表明,疏花水柏枝幼苗数量较少,种群更新存在一些障碍。空间分布格局与空间尺度及植株的大小密切相关。种群总体呈集群分布,各大小级多在9 m时出现最大的聚集强度,随着大小级的增加,聚集强度有减弱的趋势。幼苗与中株有较强的正关联。由于种群现有生境变化较大,应考虑迁地保护,并对原生种群加强长期动态监测;同时,开展疏花水柏枝适应机理研究,实施科学保护。     

林木基因组及功能基因克隆研究概述

在美国能源部资助下, 首个多年生木本植物-- 杨树的全基因组测序已经完成且序列信息已对公众开放。杨树全基因组测序的完成标志着林木基因组进入后基因组研究时代。克隆控制重要性状的主效基因是林木后基因组时代的主要研究内容。近年来, 在一些重要作物, 如水稻、蕃茄及玉米中, 先后成功克隆了多个控制重要农艺性状的主效基因, 分子育种在作物中已进入实用阶段。林木相对于这些重要作物而言, 分子遗传学的研究起步较晚, 同时, 由于林木自身的一些生物学特性, 在林木中精确定位与克隆未知基因一度被视为遗传学研究领域的难点。随着技术和研究手段的不断进步, 以及林木基因组资源的快速积累, 有望在这一领域取得突破, 为在林木中开展分子育种创造条件。文章综述了国际上林木基因组与功能基因克隆研究的现状与新发展, 并对后基因组时代的林木功能基因克隆研究的预期成果进行了展望, 以期为从事该领域研究的科研人员提供参考。