Parasitic mites influence intra‐ and interpopulational variation in sperm length in a simultaneous hermaphrodite land snail (Gastropoda: Helicidae)

Sperm morphology can be highly variable among species, but less is known about patterns of population differentiation within species. Sperm morphology is under strong sexual selection, may evolve rapidly, and often co‐varies with other reproductive traits that differ between populations. We investigated variation in sperm morphology in the simultaneous hermaphrodite land snail Arianta arbustorum in relation to parasitic mite infection. Variation in total sperm length and sperm head length was assessed in 23 populations sampled across the distributional range of the species in Central and Northern Europe. We found a pronounced variation in total sperm length among the populations studied, with a difference of 11.0% of total sperm length between the shortest and longest population means. Differences among populations explained 62.9% of the variance in total sperm length, differences among individual snails within population 23.4% and differences within individual snail 13.7%. Mantel tests showed that interpopulation differences in total sperm length increased significantly with geographical distance between populations. A minimal adequate model revealed that parasitic infection had a positive effect and longitude a negative effect on total sperm length. Thus, independent of the population examined, mite‐infected individuals of A. arbustorum produced larger sperm than uninfected snails and total sperm length decreased from west to east. Sperm head length also varied among populations, but it was not influenced by any of the factors examined. In a subsample of 12 populations restricted to the mountains of Switzerland (elevational range 440–2485 m a.s.l.), total sperm length decreased with increasing elevation. Our results suggest that selection pressures acting among populations may differ from those acting within. Stabilizing selection might be a possible mechanism for producing the reduced variation observed in sperm length within a population. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 113 , 1036–1046.     

Genetic diversity of noroviruses in Brazil

Norovirus (NoV) infections are a major cause of acute gastroenteritis outbreaks around the world. In Brazil, the surveillance system for acute diarrhoea does not include the diagnosis of NoV, precluding the ability to assess its impact on public health. The present study assessed the circulation of NoV genotypes in different Brazilian states by partial nucleotide sequencing analysis of the genomic region coding for the major capsid viral protein. NoV genogroup II genotype 4 (GII.4) was the prevalent (78%) followed by GII.6, GII.7, GII.12, GII.16 and GII.17, demonstrating the great diversity of NoV genotypes circulating in Brazil. Thus, this paper highlights the importance of a virological surveillance system to detect and characterize emerging strains of NoV and their spreading potential.     

Chemical variation within and between individuals of the lichenized ascomycete Tephromela atra

HPLC-analysis was used to determine the concentrations of the lichen compounds alectoronic acid (depsidon), -collatolic acid (depsidon) and atranorin (depsid) in the lichenized ascomycete Tephromela atra (syn. Lecanon atra) (Hudson) Hafeliner from limestone walls on the Baltic island of Öland, Sweden. In 24 individuals of T. atra sampled on a stone wall, the pre-reproductive and reproductive tissue did not differ in the concentrations of alectoronic acid, collatolic acid and atranorin. The concentrations of the three lichen compounds were inter-correlated in the reproductive tissue, but not in the pre-reproductive tissue. Single individuals of T. atra ranged in area covered from 10.1 to 147.4 cm² (mean: 38.5 cm²; N=24); 38.6% of this area was pre-reproductive tissue. However, the concentrations of the three lichen compounds were correlated neither with the total area covered by the lichen nor with the percentage of pre-reproductive tissue. This suggests that the concentrations of the lichen compounds do not change with increasing size (age) of the lichen. Analysis of specimens of T. atra from eight localities revealed a significant variation in lichen compounds (range between localities: alectoronic acid 0.60–3.26 μg/mg lichen dry weight (DW); collatolic acid 2.14–11.59 μg/mg lichen DW; atranorin 0.58–4.16 μg/mg lichen DW). The level of grazing observed in the lichens differed significantly among localities. However, no correlations between the concentrations of the three lichen compounds and the grazing damage to the lichens were found.     

嫁接对梅花耐盐性的影响

以盆栽一年生‘丰后’梅自根苗、山杏为砧木的‘丰后’梅嫁接苗以及山杏自根苗为试材,设置土壤NaCl含量分别为0(CK)、0.3%、0.6%、0.9%、1.2%和1.5%的盐胁迫处理,观测3种植物盐害情况及其叶片细胞膜透性、抗氧化酶活性、有机渗透调节物质含量的变化,并应用隶属函数值法对各盐浓度处理下3种材料叶片的生理指标进行综合评定,以明确它们的耐盐能力,为梅花向盐渍土分布较广的北方地区推广应用,以及梅花繁殖方法及梅花砧木的选择提供理论依据。结果表明:(1)随着土壤中NaCl含量的递增,‘丰后’梅自根苗、‘丰后’梅嫁接苗及山杏的盐害指数和盐害率不断增大,三者盐害指数在50%时土壤NaCl含量分别是0.545%、0.695%和0.705%,表明3种材料耐盐性由强到弱依次为山杏‘丰后’梅嫁接苗‘丰后’梅自根苗。(2)随着盐胁迫时间的延长,3种植物苗木叶片相对电导率(RC)和丙二醛(MDA)含量整体呈先上升后下降的趋势;‘丰后’梅自根苗过氧化物酶(POD)活性总体呈上升趋势,‘丰后’梅嫁接苗和山杏总体均呈现上升趋势,但个别浓度呈先上升后下降趋势;‘丰后’梅自根苗可溶性糖(SS)含量整体呈现上升趋势,‘丰后’梅嫁接苗和山杏均总体呈先下降后上升趋势,但个别较高浓度呈先上升后下降趋势。(3)隶属函数值法对盐抗性的综合评定结果为:山杏‘丰后’梅嫁接苗‘丰后’梅自根苗,综合评定结果与3种材料的盐害指数分析结果一致。研究发现,3种植物叶片所受到盐伤害的程度随NaCl胁迫浓度提高而加深,但植株叶片能对中低盐浓度处理产生一定的适应性;以耐盐性较强的山杏作为嫁接砧木后,‘丰后’梅嫁接苗比其自根苗的耐盐性增强,证明嫁接对梅花耐盐性具有一定的促进作用。     

Gene targeting in plants

Although the generation of transgenic plants is now routine, the integration of foreign genetic information has so far been at random sites in the genome. We now present evidence for directed integration into a predicted location in the host plant genome. Protoplasts of transgenic tobacco (Nicotiana tabaccum) plants carrying copies of a partial, non-functional drug-resistance gene in the nuclear DNA were used as recipients for DNA molecules containing the missing part of the gene. Molecular and genetic data confirm the integration of the foreign DNA through homologous recombination within overlapping parts of the protein coding region, resulting in the formation of an active gene in the host chromosome. This approach is referred to as gene targeting. The gene targeting frequency (the number of drug-resistant clones resulting from gene correction compared to the number of resistant clones from parallel experiments with a similar non-interrupted hybrid gene) was 0.5-4.2×10^-4. These experiments demonstrate the possibility of producing transgenic plants with desired modifications to a specific nuclear gene.     

盐节木同化枝的腋芽丛生与快速繁殖

本文通过同化枝腋芽丛生方式建立了盐生植物盐节木的快速繁殖体系。以在MS附加200 mmol·L-1 Na Cl的培养基上无菌种子萌发、生长共计4~5个月、高约3~4 cm的盐节木小苗为材料,从上截取0.5 cm长的同化枝小段为外植体,培养在MS附加不同浓度的6-BA与NAA的培养基中。结果表明:同化枝腋芽诱导与增殖最佳培养基均为MS+0.05 mg·L-1 6-BA+1mg·L-1 NAA或MS+1 mg·L-1 6-BA,初代培养30 d后,腋芽诱导率达97.5%,平均芽增殖系数为2.50;继代增殖培养时,将同化枝切成1 cm长的小段芽增殖系数提高到4.92;一次性芽苗伸长与生根培养基为MS+0.05 mg·L-1 IBA,生根率达99%;小苗经炼苗后移栽到沙子、营养土和蛭石体积比为1:1:1的基质中,成活率可达91%。     

The haplotype-relative-risk (HRR) method for analysis of association in nuclear families.

One major problem in studying an association between a marker locus and a disease is the selection of an appropriate group of controls. However, this problem of population stratification can be circumvented in a quite elegant manner by family-based methods. The haplotype-relative-risk (HRR) method, which samples nuclear families with a single affected child and uses the parental haplotypes not transmitted to that child as a control individual, represents such a method for estimating the relative risk of a marker phenotype. In the special case of a recessive disease, it was already known that the equivalence of the HRR method with the classical relative risk (RR) obtained from independent samples holds only if the probability theta of a recombination between marker and disease locus is zero. We extend this result to an arbitrary mode of inheritance. Furthermore, we compare the distribution of the estimators for HRR and RR and show that, in the case of a positive linkage disequilibrium between a marker and disease allele, the distribution of the estimator for HRR is (stochastically) smaller than that for RR, irrespective of the recombination fraction. The practical implication of this result is that, for the HRR method, there is no tendency to give unduly high risk estimators, even for theta > 0. Finally, we give an expression for the standard error of the estimator for HRR by taking into account the nonindependence of transmitted and nontransmitted parental marker alleles in the case of theta > 0.     

无症状吸烟者的肺功能改变情况分析

目的：探讨烟龄215年,日吸烟量≥15支的无症状男性吸烟者的肺功能改变情况。方法：选择男性无症状吸烟者190人及非吸烟者180人,进行肺功能测定,并比较两组人群的肺功能改变情况。结果：吸烟组与非吸烟组比较,肺活量（VC）、用力肺活量（FVC）、第1秒用力呼气容积（FEV1）、Tiffeneau1秒率（FEV1／VC）结果改变不明显,而Gaensler1秒率（FEV1/FVC）、最大分钟通气量（MVV）、用力呼气50％肺活量的呼气流量（FEF50％）、用力呼气75％肺活量的呼气流量（FEF75％）、呼出25％-75％肺活量时的平均流量（FEF25％～75％）、肺一氧化碳弥散量（DLCO）结果均有显著降低,有统计学意义。结论：通过对无症状吸烟人群肺功能测定结果进行分析。发现有些吸烟者虽无临床症状,但已经出现了小气道及肺弥散功能的损伤,提醒吸烟者应早期戒烟,关爱自身健康,净化生存环境,提高生活质量。