Genome-scale patterns in the loss of heterozygosity incidence in Saccharomyces cerevisiae

Former studies have established that loss of heterozygosity can be a key driver of sequence evolution in unicellular eukaryotes and tissues of metazoans. However, little is known about whether the distribution of loss of heterozygosity events is largely random or forms discernible patterns across genomes. To initiate our experiments, we introduced selectable markers to both arms of all chromosomes of the budding yeast. Subsequent extensive assays, repeated over several genetic backgrounds and environments, provided a wealth of information on the genetic and environmental determinants of loss of heterozygosity. Three findings stand out. First, the number of loss of heterozygosity events per unit time was more than 25 times higher for growing than starving cells. Second, loss of heterozygosity was most frequent when regions of homology around a recombination site were identical, about a half-% sequence divergence was sufficient to reduce its incidence. Finally, the density of loss of heterozygosity events was highly dependent on the genome’s physical architecture. It was several-fold higher on short chromosomal arms than on long ones. Comparably large differences were seen within a single arm where regions close to a centromere were visibly less affected than regions close, though usually not strictly adjacent, to a telomere. We suggest that the observed uneven distribution of loss of heterozygosity events could have been caused not only by an uneven density of initial DNA damages. Location-depended differences in the mode of DNA repair, or its effect on fitness, were likely to operate as well.     

依托咪酯联合右美托咪定对高血压基底节区脑出血患者脑糖氧代谢和氧化应激的影响

摘要 目的：观察依托咪酯联合右美托咪定对高血压基底节区脑出血患者脑糖氧代谢和氧化应激的影响。方法：纳入2020年1月-2022年12月期间我院收治的90例高血压基底节区脑出血患者,采用随机数字表法将患者分为对照组和研究组,各为45例。对照组患者接受依托咪酯乳状注射液麻醉,研究组患者接受依托咪酯乳状注射液联合右美托咪定注射液麻醉。对比两组血流动力学[心率（HR）、平均动脉压（MAP）]、糖氧代谢指标[氧饱和度（SjvO₂）、脑氧摄取率（CEO₂）、脑动静脉氧差（AVDO₂）]、氧化应激指标[丙二醛（MDA）和超氧化物歧化酶（SOD）]和不良反应。结果：麻醉诱导后5 min（T1）~手术完毕时（T4）时间点,研究组心率（HR）、平均动脉压（MAP）低于对照组（P<0.05）。T4时间点,研究组SjvO₂高于对照组,CEO₂、AVDO₂低于对照组（P<0.05）。T4时间点,研究组SOD高于对照组,MDA低于对照组（P<0.05）。两组不良反应总发生率对比未见差异（P>0.05）。结论：依托咪酯联合右美托咪定可更好维持机体血流动力学,改善脑糖氧代谢,减轻氧化应激,对高血压基底节区脑出血患者发挥出良好的麻醉效果。     

转录因子在植物干旱应激中的功能研究进展

转录因子是一种多功能蛋白,在感知应激信号、应答相应应激基因表达及传导应激信号中起着关键作用。干旱是影响植物生长发育的主要非生物胁迫之一。为了适应干旱环境,植物发展了复杂的分子机制,其中转录因子可同时控制多种途径调控干旱应激,是操纵调控和应激响应途径的有力工具。近年来,越来越多的植物转录因子的功能被阐明,了解转录因子在干旱应激的功能,对植物的工程抗旱有重要的实践意义。综述转录因子在植物干旱应激中的功能研究进展,以期为今后转录因子的研究和利用提供理论依据,培育具有较强抗旱能力的植物。     

拟南芥DTX31基因表达研究

以模式植物拟南芥为材料,通过PCR和RT-PCR在DNA和RNA水平上筛选鉴定了DTX31基因对应的T-DNA插入突变体,对其表型变化进行了观察.通过半定量RT-PCR分析检测了DTX31基因在拟南芥不同器官及环境胁迫响应中的表达情况,结果发现:DTX31基因在根中表达最高,而在茎、叶、叶柄、花中的表达则较弱;盐和赤霉素使DTX31基因的表达迅速升高,盐胁迫2 h后的表达量达到最高峰,GA处理1 h时就达到最高峰,热激使DTX31基因的表达变化不明显.因此,推测该基因可能是盐和GA信号传导通路中的一个重要调控因子.     

孕期应激对子代大鼠骨髓淋巴干细胞发育的影响

孕期应激对子代产生的影响是多方面的,这种影响是复杂的。研究表明,出生前的应激经历可导致出生后子代长期的免疫功能改变。这些改变追其根源与骨髓淋巴干细胞的改变有关。本文综述了大鼠孕期经历应激的子代骨髓淋巴干细胞所受的影响及免疫系统的相关改变,并根据现有的研究提出假说,为进一步研究孕期应激导致子代免疫系统改变的机理研究提供新的思路。     

Nucleoli and Stress Granules: Connecting Distant Relatives

Nucleoli and cytoplasmic stress granules (SGs) are subcellular compartments that modulate the response to endogenous and environmental signals to control cell survival. In our opinion, nucleoli and SGs are functionally linked; they are distant relatives that combine forces when cellular homeostasis is threatened. Several lines of evidence support this idea; nucleoli and SGs share molecular building blocks, are regulated by common signaling pathways and communicate when vital cellular functions become compromised. Together, nucleoli and SGs orchestrate physiological responses that are directly relevant to stress and human health. As both compartments have established roles in neurodegenerative diseases, cancer and virus infections, we propose that these conditions will benefit from therapeutic interventions that target simultaneously nucleoli and SGs.      

山黧豆抗逆性研究进展

山黧豆是一种栽培历史悠久、种植广泛的豆科作物,具有很高的蛋白质含量和极强的耐旱能力,因而成为一些干旱、贫困和人口众多地区的主要饲料和粮食作物,且被考虑作为可持续发展农业的模式作物。随着人类对粮食、蛋白质和新型食物资源需求的日益增长,山黧豆的研究引起了世界各国学者的重视。该文对国内外近年来有关山黧豆在干旱、盐、重金属及生物胁迫下抗逆性方面的研究进展作了概述,同时简要介绍了山黧豆与干旱相适应的形态特征,并对亟需重点研究的几个方向作了展望。     

Greenhouse evaluation of fitness-related reproductive traits in roundup<Superscript>®</Superscript>-tolerant transgenic creeping bentgrass (<Emphasis Type="Italic">Agrostis Stolonifera</Emphasis> L.)

Summary Creeping bentgrass is a very important turfgrass species used extensively on golf course greens, fairways, and tees. One of the challenges of creeping bentgrass management is the control of grassy weeds, most of which respond to herbicides in a similar manner to that of creeping bentgrass. As part of a weed management program for golf courses, Roundup^?-tolerant creeping bentgrass will be simple to employ and more effective in controlling problem weeds than currently available methods. The goal of this research was to evaluate fitness-related reproductive traits in four transgenic creeping bentgrass events modified to express a Roundup^?-tolerant gene, cp4 epsps, to determine if these creeping bentgrass events had gained an unexpected reproductive fitness advantage. We compared transgenic events ASR 333, ASR801 with their nontransformed tissue culture line, C99056L and transgenic events ASR365, ASR368 with their non-transformed tissue culture line, B99061R. Populations of plants from three conventional cultivars were also included for comparison to determine whether significant variations, if present in transgenic events, were novel to the non-transformed organism, Agrostis stolonifera L. Our results showed that none of the four transgenic events surveyed were significantly different from the respective non-transformed tissue culture line plants for the following characteristics: first heading date, anthesis duration, inflorescence length, number of florets per inflorescence, pollen size, and seed-set capacity through open-pollination. One of the transgenic events, ASR333, needed significantly more days for anthesis initiation than the nontransformed tissue culture line, C99056L; while another transgenic event, ASR801, exhibited significantly shorter pollen longevity than plants of the tissue culture line, C99056L. However, ASR801 was not significantly different from the conventional cultivars ‘Penn A-4’ and ‘Penncross’ for pollen longevity. Plants of both transgenic events ASR365 and ASR368 did not differ significantly from plants of the tissue culture line, B99061R, for all characters measured.