An evolutionary scenario for genomic imprinting of Impact lying between nonimprinted neighbors.

Mouse Impact is the sole imprinted gene mapped to chromosome 18 to date. Despite its remarkable evolutionary conservation, human IMPACT was shown to escape genomic imprinting. Here we identified Hrh4 and Osbpl1 as the distal and proximal nearest neighbors of Impact, respectively, and found that both genes are expressed biallelically. Thus, in contrast with most imprinted genes, Impact fails to show apparent physical clustering with other imprinted genes. Since Impact not only lies in an intergenic region but also consists of 11 exons, it does not seem to be an imprinted gene generated by a retrotransposition. Hazardous effects of overexpressed Impact, a genomic segment containing paralogues of Hrh4 and Osbpl1 but not of Impact, and enhanced promoter activity in the mouse led us to propose an alternative model. This model assumes that segmental duplication followed by enhancement of the promoter activity in the lineage to mouse is responsible for the species-specific imprinting of Impact.     

稀土元素对生物机体剂量效应机理的研究

综述了稀土元素对生物机体剂量效应的机理,从稀土对细胞质膜、细胞周期及细胞凋亡、CaM水平调节的作用到对蛋白质、DNA的影响等不同层次和水平进行了探讨,以期为稀土在生物学领域的进一步广泛应用奠定理论基础.     

Fixed-Width Estimation of the Mean of Logistic Response Function Using Spearman-Karber Estimator

In this paper we study the asymptotic properties of the sequential fixed-width rule developed for the estimation of the mean of the logistic response function based on the quantal responses observed at equally spaced dose levels. The Spearman-Karber (S-K) and Spearman-type variance (S-T-V) estimator are used for the mean and variance, respectively, in the sequential estimation. We compute the coverage probabilities and stop     

昆虫病原线虫对草地贪夜蛾幼虫的致死率及田间防治效果

【目的】为生产中应用昆虫病原线虫防治草地贪夜蛾提供参考。【方法】采用室内实验和田间试验相结合的方法,室内培养皿中测定4种不同品系线虫对3和6龄草地贪夜蛾幼虫的毒力、致死时间和剂量,田间玉米6～8叶期、日落后叶面喷施线虫至喇叭口内,测试防治草地贪夜蛾的施用剂量和持效天数。【结果】Steinernema feltiae SN、Heterorhabditis bacteriophora H06、Heterorhabditis beicherriana Cherry和Oscheius chongmingensis Tumian侵染草地贪夜蛾3龄幼虫72 h后的致死中浓度LC₅₀分别为22.13、36.54、60.01和1369.4 IJs·larva^-1;侵染6龄幼虫72 h后的致死中浓度LC₅₀分别为18.67、31.25、45.52和897.28 IJs·larva^-1。SN、H06、Cherry和Tumian品系的最佳致死时间72 h;最佳致死剂量100 IJs·larva^-1(...     

Mechanisms of sex determination and X-chromosome dosage compensation

Abnormalities in chromosome number have the potential to disrupt the balance of gene expression and thereby decrease organismal fitness and viability. Such abnormalities occur in most solid tumors and also cause severe developmental defects and spontaneous abortions. In contrast to the imbalances in chromosome dose that cause pathologies, the difference in X-chromosome dose used to determine sexual fate across diverse species is well tolerated. Dosage compensation mechanisms have evolved in such species to balance X-chromosome gene expression between the sexes, allowing them to tolerate the difference in X-chromosome dose. This review analyzes the chromosome counting mechanism that tallies X-chromosome number to determine sex (XO male and XX hermaphrodite) in the nematode Caenorhabditis elegans and the associated dosage compensation mechanism that balances X-chromosome gene expression between the sexes. Dissecting the molecular mechanisms underlying X-chromosome counting has revealed how small quantitative differences in intracellular signals can be translated into dramatically different fates. Dissecting the process of X-chromosome dosage compensation has revealed the interplay between chromatin modification and chromosome structure in regulating gene expression over vast chromosomal territories.     

IGF-1R的表达与XELOX方案化疗治疗晚期胃癌的临床疗效的相关性分析

目的:探讨晚期胃癌患者中胰岛素样生长因子1型受体(IGF-1R)的表达与卡培他滨联合奥沙利铂(XELOX)方案化疗疗效的关系。方法:收集56例一线接受XELOX化疗的晚期胃癌患者的临床、病理资料,采用免疫组化法检测其IGF-1R的表达情况,计算客观有效率(ORR)和疾病控制率(DCR),统计分析IGF-1R的表达与胃癌患者临床病理特征、近期疗效、临床受益率及毒副反应发生情况的关系。结果:56例患者中,IGF-1R的阳性率为69.6%,其中未分化-低分化腺癌患者IGF-1R的阳性率显著高于中-高分化腺癌(76.5%vs.59.1%,P0.05)。56例患者的ORR为28.6%,DCR为55.3%。与IGF-1R(-)的胃癌患者相比,IGF-1R(+)的胃癌患者ORR、DCR及临床受益率均显著降低(ORR:23.1%vs.41.1%;DCR:48.7%vs.70.5%;临床受益率:51.3%vs.70.6%)(P0.05)。IGF-1R的表达与XELOX方案所致化疗毒副反应无显著相关性(P0.05)。结论:IGF-1R的表达可能成为预测胃癌化疗疗效及预后的新指标,IGF-1R(-)的胃癌患者可能更能从XELOX化疗方案中获益。     

The Effects of Varying Chromosome Arm Dosage on Maize Plant Morphogenesis

Maize is an especially well-suited species for studying the effects of aneuploidy on plant development. We used B-A translocations and testers that were crossed seven times into inbred W22 to generate a dosage series for 14 chromosome arms. This is the first report of dosage effects on maize morphogenesis using inbred B-A stocks and inbred tester stocks. We compared plants containing one dose or three doses of each of the 14 chromosome arms with plants containing two doses for seven measured traits. These were leaf width, leaf length, plant height, ear height, internode length, ear node circumference, and tassel branch number. We observed the typical maize aneuploid syndrome wherein one dose was more widespread and more severe in its effects than three doses. All but two of the one-dose effects were negative, and all of the three-dose effects were negative. The occurrence of positive responses by hyperploid plants in our earlier B-A-A study and the absence of any positive responses among the hyperploids reported for the 14 simple B-A translocations tested for dosage effects in the present study and previously may reflect gene dosage interaction between the two chromosome arm segments present in the B-A-A translocations. The overall congruence of our results with those of previous studies suggests that the traits measured are quantitative traits controlled by multiple genes whose activities provide a balanced regulation that transcends individual inbred lines or diverse genetic backgrounds and that such genes may be especially abundant in chromosome arm 1L.     

结核丸联合含环丝氨酸化疗方案对耐多药肺结核患者肺功能和外周血Th1/Th17细胞免疫反应的影响

摘要 目的：探讨结核丸联合含环丝氨酸化疗方案对耐多药肺结核（MDR-TB）患者肺功能和外周血辅助性T细胞（Th）1/Th17细胞免疫反应的影响。方法：将我院于2018年5月~2020年3月期间收治的98例MDR-TB患者根据信封抽签法分为对照组（49例,含环丝氨酸化疗方案治疗）和观察组（49例,结核丸联合含环丝氨酸化疗方案治疗）。对比两组痰菌阴转率、病灶吸收率、空洞闭合率、肺功能指标、外周血Th1/Th17细胞免疫反应相关指标和不良反应发生率。结果：观察组的病灶吸收率、痰菌阴转率、空洞闭合率均高于对照组,不良反应总发生率显著低于对照组（P<0.05）。观察组治疗后最大呼气流量（PEF）、第1秒用力呼气容积（FEV₁）、用力肺活量（FVC）高于对照组同期（P<0.05）。观察组治疗后Th1、γ-干扰素（IFN-γ）高于对照组同期,Th17、白细胞介素（IL）-17低于对照组同期（P<0.05）。结论：含环丝氨酸化疗方案联合结核丸治疗MDR-TB,可有效改善患者的肺功能,调节外周血Th1/Th17细胞免疫反应。