基于ISSR标记的辽宁4个东北林蛙种群遗传多样性分析

辽宁是东北林蛙Rana dybowskii主要分布地之一,种群数量巨大,其群体遗传多样性有待评估.本研究应用ISSR标记技术对东北林蛙4个种群105个样本进行研究,5个引物共获得44条清晰谱带,4个种群的多态位点率均大于75%,Nei's基因多样性为0.2851,Shannon信息指数为0.4476,显示了较高的遗传多样性.对遗传分化系数、Nei's遗传距离、AMOVA分子变异巢式方差分析和F-统计量等遗传参数的统计结果表明,辽宁东北林蛙种群间已经出现一定程度的遗传分化,分析认为,自然屏障(高山和平原等)以及栖息地片段化是其遗传分化形成的主要因素.     

血液磁极化疗法对糖尿病兔胰岛功能的影响

目的观察血液磁极化疗法(简称血磁治疗)对糖尿病(DM)的治疗效果和对胰岛功能的影响。方法制备了四氧嘧啶DM兔模型20只,随机分为两组,即DM模型血磁治疗组及DM模型未治疗组,同时设立正常对照组10只,分别测定治疗前后空腹血糖(FPG)、糖化血红蛋白(HbA1c)、胰岛素(INS)及C-肽(C-P),并于观察期结束后处死动物取胰腺组织常规石蜡包埋切片,行HE及Mallory三色法特殊染色观察3组胰岛形态学变化。结果血磁治疗显著降低DM兔的FPG(P<0.001)。DM治疗组INS及C-P水平较治疗前明显升高(P<0.01),与未治疗组相比差异显著(P<0.05)。胰岛病理改变可见治疗组β细胞数量明显多于DM未治疗组,提示血磁疗法具有促进胰岛修复,改善胰岛功能的作用。结论血磁疗法能够促进DM时受损胰岛组织的修复,改善胰岛β细胞分泌功能,降血糖作用明显。     

Grid technology in tissue-based diagnosis: fundamentals and potential developments

DNA fluorescence in situ hybridization (FISH) technology is used to study chromosomal and genomic changes in fixed cell suspensions and tissue block preparations. The technique is based on specific hybridization of small labeled DNA fragments, the probes, to complementary sequences in a target DNA molecule. Demand for FISH assays in formalin-fixed, paraffin-embedded tissues has been increasing, mainly in conditions in which diagnosis is not achieved in cell smears or tissue imprints, such as solid tumors. Moreover, the development of molecular targeted therapies in oncology has expanded the applicability of tests to predict sensitivity or resistance to these agents. The efficient use of tyrosine kinase inhibitors (TKI) of the epidermal growth factor receptor (EGFR) as therapeutical agents in advanced non-small cell lung cancer (NSCLC) depends on identification of patients likely to show clinical benefit from these specific treatments. The EGFR gene copy number determined by FISH has been demonstrated as an effective predictor of outcome from NSCLC patients to EGFR TKIs; however there are pending challenges for standardization of laboratory procedures and definition of the scoring system. This methodology article focuses on the EGFR FISH assay. It details the scoring system used in the studies conducted at the University of Colorado Cancer Center in which a significant association was found between increased EGFR copy numbers and clinical outcome to TKIs, and proposes interpretative guidelines for molecular stratification of NSCLC patients for TKI therapy.     

犬MC1R基因T105A基因座多态性及 与毛色性状相关性的研究The

为了检测犬MC1R基因T105A基因座的多态性,并分析该多态性与犬毛色表型的相关性,抽取111只外科手术学实验用杂种犬血液并提取DNA,记录毛色表型。采用PCR-RFLP技术,对MC1R基因T105A基因座进行基因多态性分析,并对该基因座DNA进行克隆测序;用二元变量相关分析的统计学方法分析基因座多态性与毛色性状之间的相关性。经PCR-RFLP分析结果表明,T105A基因座序列具有多态性,表现为A、B二个等位基因和AA、AB及BB 3种基因型。A、B等位基因频率分别为72.97%和27.03%,基因杂合度（H）为0.39。基因型AA频率为55.86%,BB为9.91%,AB为34.23%。对T105A多态性片段DNA克隆测序后发现,MC1R基因在编码第105位氨基酸的密码子第一个碱基存在由G到A的单碱基突变,该突变导致第105位氨基酸发生由丙氨酸向苏氨酸的改变。统计分析结果表明MC1R基因T105A基因座的多态性与毛色性状不存在显著的相关性,这可能是由于外科手术学实验用犬是杂种犬,其遗传背景不同所致,尚须在纯种犬群体中进一步研究MC1R基因对毛色的影响。 Abstract: In order to detect the polymorphism of T105A in MC1R gene in dogs and to analyze the relationship between the genetic polymorphisms and phenotypes of dog coat color, the blood samples of 111 cross-breed dogs were taken and their genomic DNAs were extracted. The phenotypes of dog coat color were recorded. The T105A locus of MC1R gene in the canine was detected through the technology of PCR-RFLP. Furthermore, the polymorphic fragments at T105A were sequenced. The relationships between the polymorphism of T105A and coat color trait were analyzed by the statistical methods of bivarate correlation analysis. By the method of PCR-RFLP, the T105A polymorphism was found with two alleles A and B and three genotypes AA, AB and BB. The frequencies of two alleles were 72.97% and 27.03%, respectively. The heterozygosity of T105A locus was 0.39. The frequencies of three genotypes were 55.86%, 34.23% and 9.91%, respectively. According to the results of sequencing, one base change from G to A at the position 105 was found at T105A locus and it altered amino acid at the position 105 from alanine to threonine. According to the statistical analysis, no significant association between the polymorphism of MC1R gene and the coat color was found and the result may be due to the differences of genetic background. Further research on MC1R gene should be done in pure breed dogs.     

Two regulatory RNA elements affect TisB‐dependent depolarization and persister formation

Bacterial survival strategies involve phenotypic diversity which is generated by regulatory factors and noisy expression of effector proteins. The question of how bacteria exploit regulatory RNAs to make decisions between phenotypes is central to a general understanding of these universal regulators. We investigated the TisB/IstR‐1 toxin‐antitoxin system of Escherichia coli to appreciate the role of the RNA antitoxin IstR‐1 in TisB‐dependent depolarization of the inner membrane and persister formation. Persisters are phenotypic variants that have become transiently drug‐tolerant by arresting growth. The RNA antitoxin IstR‐1 sets a threshold for TisB‐dependent depolarization under DNA‐damaging conditions, resulting in two sub‐populations: polarized and depolarized cells. Furthermore, our data indicate that an inhibitory 5′ UTR structure in the tisB mRNA serves as a regulatory RNA element that delays TisB translation to avoid inappropriate depolarization when DNA damage is low. Investigation of the persister sub‐population further revealed that both regulatory RNA elements affect persister levels as well as persistence time. This work provides an intriguing example of how bacteria exploit regulatory RNAs to control phenotypic heterogeneity.     

根施甜菜碱对镍胁迫下小麦幼苗生长生理的影响

以普通小麦品种‘轮选988’为材料,采用溶液培养法,研究了根施不同浓度甜菜碱(1.0、2.0、3.0、4.0、5.0、10.0、15.0、20.0mmol·L~(-1))对镍(100μmol·L~(-1) NiSO_4)胁迫下小麦根系生长的影响,以及4.0mmol·L~(-1)甜菜碱处理镍胁迫幼苗根系相关抗逆生理生化指标的变化。结果表明:(1)与不施加镍对照相比,镍胁迫下小麦幼苗的根长、株高、鲜重和干重分别显著降低了14.7%、11.7%、15.0%和16.7%。(2)与单独镍胁迫处理相比,小麦幼苗的根长、株高、鲜重和干重均随着根施甜菜碱的浓度逐渐增加且呈先升后降的趋势,并以4.0mmol·L~(-1)外源甜菜碱处理效果较佳。(3)与单独镍胁迫处理相比较,在4.0mmol·L~(-1)外源甜菜碱处理下,小麦幼苗根系超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX)活性分别升高了284.7%、40.3%、82.9%和20.4%,超氧阴离子自由基(O-·2)含量、过氧化氢(H_2O_2)含量和丙二醛(MDA)含量分别显著降低了50.6%、38.4%和40.6%,可溶性糖含量及游离脯氨酸(Pro)含量分别显著降低了19.2%、45.4%,而根系活力大幅上升了358.0%。研究认为,根施适宜浓度外源甜菜碱可显著增强小麦幼苗根系的抗氧化能力,恢复根系活力,从而有效减弱镍胁迫对小麦幼苗生长的伤害。     

Surface N balances and reactive N loss to the environment from global intensive agricultural production systems for the period 1970-2030

Data for the historical years 1970 and 1995 and the FAO-Agriculture Towards 2030 projection are used to calculate N inputs (N fertilizer, animal manure, biological N fixation and atmospheric deposition) and the N export from the field in harvested crops and grass and grass consumption by grazing animals. In most industrialized countries we see a gradual increase of the overall N recovery of the intensive agricultural production systems over the whole 1970-2030 period. In contrast, low N input systems in many developing countries sustained low crop yields for many years but at the cost of soil fertility by depleting soil nutrient pools. In most developing countries the N recovery will increase in the coming decades by increasing efficiencies of N use in both crop and livestock production systems. The surface balance surplus of N is lost from the agricultural system via different pathways, including NH3 volatilization, denitrification, N2O and NO emissions, and nitrate leaching from the root zone. Global NH3-N emissions from fertilizer and animal manure application and stored manure increased from 18 to 34 Tg·yr-1 between 1970 and 1995, and will further increase to 44 Tg·yr-1 in 2030. Similar developments are seen for N2O-N (2.0 Tg·yr-1 in 1970, 2.7 Tg·yr-1 in 1995 and 3.5 Tg·yr-1 in 2030) and NO-N emissions (1.1 Tg·yr-1 in 1970, 1.5Tg·yr-1 in 1995 and 2.0 Tg·yr-1 in 2030).     

Photooxidative stress‐induced and abundant small RNAs in Rhodobacter sphaeroides

Exposure to oxygen and light generates photooxidative stress by the bacteriochlorophyll a mediated formation of singlet oxygen (¹O₂) in Rhodobacter sphaeroides. Our study reports the genome‐wide search for small RNAs (sRNAs) involved in the regulatory response to ¹O₂. By using 454 pyrosequencing and Northern blot analysis, we identified 20 sRNAs from R. sphaeroides aerobic cultures or following treatment with ¹O₂ or superoxide (O^–₂). One sRNA was specifically induced by ¹O₂ and its expression depends on the extracytoplasmic function sigma factor RpoE. Two sRNAs induced by ¹O₂ and O^–₂ were cotranscribed with upstream genes preceded by promoters with target sequences for the alternative sigma factors RpoH_I and RpoH_II. The most abundant sRNA was processed in the presence of ¹O₂ but not by O^–₂. From this and a second sRNA a conserved 3′‐segment accumulated from a larger precursor. Absence of the RNA chaperone Hfq changed the half‐lives, abundance and processing of ¹O₂‐affected sRNAs. Orthologues of three sRNA genes are present in different alpha‐proteobacteria, but the majority was unique to R. sphaeroides or Rhodobacterales species. Our discovery that abundant sRNAs are affected by ¹O₂ exposure extends the knowledge on the role of sRNAs and Hfq in the regulatory response to oxidative stress.     

The largest animal association centered on one species: the army ant <Emphasis Type="Italic">Eciton burchellii</Emphasis> and its more than 300 associates

As possibly two of the last true naturalists, Carl Rettenmeyer and his wife Marian dedicated their lives to the study of army ants and their associates. Over the course of 55 years, the Rettenmeyers went on numerous field trips mainly to the Central American tropics and analyzed hundreds of self-collected samples and those sent by a multitude of other scientists, who were inspired by Carl’s enthusiasm. It comes as no surprise that Carl Rettenmeyer became the world’s leading expert on army ant associates. This paper, which the Rettenmeyers nearly completed before Carl’s death in 2009, gives the first comprehensive list of animals known to be found in the company of a single army ant species: Eciton burchellii. The 557 recorded associates range from birds to insects and mites and comprise the largest described animal association centering around one particular species. Although some of these associates may be opportunistic encounters, we are confident that approximately 300 of the recorded species depend on the ants, at least in part, for their existence. The extinction of E. burchellii from any habitat over its vast area of distribution is likely to cause the extinction of numerous associated animals at that site. This overview will hopefully inspire researchers throughout the world to follow in the Rettenmeyers’ footsteps and continue the investigation of army ants and their associates.