CTG repeats distribution and Alu insertion polymorphism at myotonic dystrophy (DM) gene in Amhara and Oromo populations of Ethiopia

Myotonic dystrophy (DM) is a dominantly inherited neuromuscular disease, highly variable and multisystemic, which is caused by the expansion of a CTG repeat located in the 3′ untranslated region of the DMPK gene. Normal alleles show a copy number of 5–37 repeats on normal chromosomes, amplified to 50–3000 copies on DM chromosomes. The trinucleotide repeat shows a trimodal allele distribution in the majority of the examined population. The first class includes alleles carrying (CTG)₅, the second class, alleles in the range 7–18 repeats, and the third class, alleles (CTG)_{≥ 19}. The frequency of this third class is directly related to the prevalence of DM in different populations, suggesting that normal large-sized alleles predispose toward DM. We studied CTG repeat allele distribution and Alu insertion and/or deletion polymorphism at the myotonic dystrophy locus in two major Ethiopian populations, the Amhara and Oromo. CTG allele distribution and haplotype analysis on a total of 224 normal chromosomes showed significant differences between the two ethnic groups. These differences have a bearing on the out-of-Africa hypothesis for the origin of the DM mutation. In addition, (CTG)_{≥ 19} alleles were exclusively detected in the Amhara population, confirming the predisposing role of these alleles compared with the DM expansion-mutation. Electronic Publication     

强直性肌营养不良症DMPK基因CTG重复序列与Alu±1kb单倍型研究

强直性肌营养不良(myotonic dystrophy,DM)是由于DMPK基因3′非翻译区CTG重复序列异常扩展所致的、主要累及神经肌肉系统的常染色体显性遗传病。在该基因的第8内含子中还存在一个Alu重复序列的1kb插入/缺失多态性,即Alu±1kb多态性。为了帮助阐明汉族人群中DM突变的起源,并为解释DM在不同群体中发病率的差异提供更多依据,本文从300例已知CTG拷贝数的正常汉族群体中随机挑选60例,首先通过PCR扩增确定其Alu±1kb多态性,然后对Alu±1kb和CTG双杂合的标本,采用长PCR方法先行扩增含Alu±1kb和CTG重复序列的DNA片段,再分别对含Alu(＋)和Alu(－)的DNA片段中的CTG拷贝数进行常规PCR分析,以确定二位点的单倍型。结果表明60例正常人中二位点间呈连锁不平衡。其单倍型为:（CTG）5均与Alu(＋)连锁;多数(CTG)11～14与Alu(－)连锁;在两个(CTG)≥19的等位基因中一个与Alu(＋)连锁,另一个与Alu(－)连锁。各民族相关资料的比较提示,汉族人群中(CTG)11～14与非洲黑人的起源可能不同;(CTG)19～30/Alu－1kb在汉族人群中的频率远比欧洲人群的高;(CTG)19～30/Alu－1kb与(CTG)19～30/Alu＋1kb在汉族人群中是以一定比例共存的;(CTG)19～30在不同民族间的起源不尽相同;如果从(CTG)5到(CTG)19～30的假设成立的话,则很可能是一个较为复杂的过程。 Abstract：Myotonic dystrophy(DM),an autosomal dominant disease of the neuromascular system,is caused by expansion of the CTG repeats in the 3＇untranslated region of the DMPK gene.In the eighth intron of this gene,there is another polymorphism－the insertion/deletion of 1kb Alu repeat(Alu±1kb).In order to help elucidate the origin of DM mutation in Chinese Han patients,and explain the difference of incidence of DM in different populations,60 normal Han individuals were randomly chosen from 300 Chinese,whose CTG copy number had been previously ascertained.The polymorphism of Alu±1kb of the 60 cases were firstly analyzed by in vitro amplification;then the 22 cases in which both sites were heterozygous were analyzed as following:the fragments containing both Alu±1kb and CTG repeat sequence were first amplified by long PCR method;and then the CTG copy numbers were analyzed in the Alu(＋)and Alu(－)alleles.In the 60 cases studied,a remarkable linkage disequilibrium between CTG triplet repeats and Alu±1kb were observed.All the(CTG)5 alleles were linked with Alu(＋),and most of the(CTG）11－14 alleles were linked with Alu(－);one of the two alleles of(CTG）≥19 was linked with Alu(＋),the other was linked with Alu(－).This suggests that the origin of(CTG)11－14 in Chinese Han may be different from that of African Blacks;the frequency of (CTG)19－30 /Alu－1kb in Chinese Han might be much higher than that in Europeans Caucasians.The(CTG)19－30/Alu－1kb and(CTG)19－30/Alu＋1kb coexist in Chinese Han in some proportion;the origin of (CTG)19－30 in different population may be different;if the hypothesis of(CTG)5 to(CTG)19－30 is true,then the progress should have been a relatively complicated process.     

强直性肌营养不良症DMPK基因CTG重复序列与Alu±1kb单倍型研究

强直性肌营养不良(myotonic dystrophy,DM)是由于DMPK基因3′非翻译区CTG重复序列异常扩展所致的、主要累及神经肌肉系统的常染色体显性遗传病。在该基因的第8内含子中还存在一个Alu重复序列的1kb插入/缺失多态性,即Alu±1kb多态性。为了帮助阐明汉族人群中DM突变的起源,并为解释DM在不同群体中发病率的差异提供更多依据,本文从300例已知CTG拷贝数的正常汉族群体中随机挑选60例,首先通过PCR扩增确定其Alu±1kb多态性,然后对Alu±1kb和CTG双杂合的标本,采用长PCR方法先行扩增含Alu±1kb和CTG重复序列的DNA片段,再分别对含Alu(＋)和Alu(－)的DNA片段中的CTG拷贝数进行常规PCR分析,以确定二位点的单倍型。结果表明60例正常人中二位点间呈连锁不平衡。其单倍型为:（CTG）5均与Alu(＋)连锁;多数(CTG)11～14与Alu(－)连锁;在两个(CTG)≥19的等位基因中一个与Alu(＋)连锁,另一个与Alu(－)连锁。各民族相关资料的比较提示,汉族人群中(CTG)11～14与非洲黑人的起源可能不同;(CTG)19～30/Alu－1kb在汉族人群中的频率远比欧洲人群的高;(CTG)19～30/Alu－1kb与(CTG)19～30/Alu＋1kb在汉族人群中是以一定比例共存的;(CTG)19～30在不同民族间的起源不尽相同;如果从(CTG)5到(CTG)19～30的假设成立的话,则很可能是一个较为复杂的过程。 Abstract：Myotonic dystrophy(DM),an autosomal dominant disease of the neuromascular system,is caused by expansion of the CTG repeats in the 3＇untranslated region of the DMPK gene.In the eighth intron of this gene,there is another polymorphism－the insertion/deletion of 1kb Alu repeat(Alu±1kb).In order to help elucidate the origin of DM mutation in Chinese Han patients,and explain the difference of incidence of DM in different populations,60 normal Han individuals were randomly chosen from 300 Chinese,whose CTG copy number had been previously ascertained.The polymorphism of Alu±1kb of the 60 cases were firstly analyzed by in vitro amplification;then the 22 cases in which both sites were heterozygous were analyzed as following:the fragments containing both Alu±1kb and CTG repeat sequence were first amplified by long PCR method;and then the CTG copy numbers were analyzed in the Alu(＋)and Alu(－)alleles.In the 60 cases studied,a remarkable linkage disequilibrium between CTG triplet repeats and Alu±1kb were observed.All the(CTG)5 alleles were linked with Alu(＋),and most of the(CTG）11－14 alleles were linked with Alu(－);one of the two alleles of(CTG）≥19 was linked with Alu(＋),the other was linked with Alu(－).This suggests that the origin of(CTG)11－14 in Chinese Han may be different from that of African Blacks;the frequency of (CTG)19－30 /Alu－1kb in Chinese Han might be much higher than that in Europeans Caucasians.The(CTG)19－30/Alu－1kb and(CTG)19－30/Alu＋1kb coexist in Chinese Han in some proportion;the origin of (CTG)19－30 in different population may be different;if the hypothesis of(CTG)5 to(CTG)19－30 is true,then the progress should have been a relatively complicated process.     

青海藏族HLA II类基因多态性的研究

用PCR-RFLP的技术进一步研究了青海藏族HLA-DPB1的多态性。在19个HLA-DPB1 的等位基因中,共检出18个等位基因。其中,*0501的频率最高（AF=38.0%）;其次为*0201（AF=20.0%）;未检出*1601。在HLA-DPB1各等位基因的分布上,藏族与中国南方汉族、中国北方汉族等无明显差异,而与高加索人及尼格罗人的差异则较为显著。综合隶属于三大人种11个群体中的HLA-DQA1、-DQB1和-DPB1基因座各等位基因的分布频率,用UPGMA方法构建了分子系统树, 实验结果进一步证实汉藏同源说。 Abstract:Following the study of the polymorphism of the HLA-DQA1and -DQB1in Tibetans of Qinghai Province, the polymorphism of the HLA-DPB1was investigated by the same technique―PCR-RFLP. Among the 19 detectable alleles of HLA-DPB1gene, 18 alleles were detected. The allele *0501 was the most frequent one (AF=38.0%); the allele *0201 (AF=20.0%）was the second one; and *1601 was not found by this technique. Compared with that of Southern Han and Northern Han nationality in China, the distribution of the alleles showed little difference; while compared with that of the Caucasoid and Negroid, it showed significant difference. The result of this report confirmed once more that the Tibetan and Han nationalities came from the same ancestors. Based on the allele frequencies of the three loci within HLAclass II region-HLA-DQA1、-DQB1and -DPB1from 11 groups among three main races in the world, a molecular phylogenetic tree was constructed with the method UPGMA.     

山东临朐人群HLA等位基因多态性 与幽门螺杆菌感染关系的研究

为了研究山东临朐地区健康人白细胞抗原（HLA）Ⅰ类等位基因多态性与幽门螺杆菌（Hp）感染的关系,运用序列特异性引物聚合酶链反应（PCR SSP）的方法,检测Hp阳性人群（90例）和Hp阴性人群（49例）的HLA Ⅰ类和Ⅱ类等位基因。结果在HLA Ⅰ类（A、B、CW）的共68个等位基因多态中,发现在感染及非感染人群中存在4个显著性差异的位点;在HLA Ⅱ类（DRB1、DQB1和DRB3、DRB4、DRB5）的共22个等位基因多态中,没有发现显著性差异的位点。A*02等位基因频率,Hp阳性低于阴性人群（OR,0.56;95%CI,0.33～0.94;P,0.029）;B*48等位基因频率,Hp阳性低于阴性人群（OR,0.15;95%CI,0.03～0.72;P,0.007）;CW*08〖STBZ〗等位基因频率,Hp阳性低于Hp阴性人群（OR,0.32;95% CI,0.15～0.69;P,0.003）;CW*15等位基因频率,Hp阳性高于Hp阴性人群（OR,5.11;95%CI,0.63～40.90;P,0.024）。结果表明HLA Ⅰ类等位基因的多态性可能与山东临朐地区Hp的易感性有关;HLA Ⅱ类等位基因的多态性可能与其无关。HLA Ⅰ类等位基因中,CW*15可能是Hp感染的易感基因;A*02、B*48和CW*08可能是保护性基因。Abstract: In order to analyze the relationship of HLA polymorphisms and the infection of H.pylori in the population of Linqu County in Shandong Province,polymerase chain reaction with sequence specific primers(PCR SSP) was used to determine the alleles of HLA typeⅠand Ⅱ in 90 Hp positive persons and 49 Hp negative controls.The results showed that among the 68 alleles of HLA typeⅠ,4 alleles were found significantly different between Hp positive and Hp negative population,while no significant difference was found among the 22 alleles of HLA typeⅡ.Hp positive persons had a lower allele frequency of A*02（OR=0.56,95% CI=0.33～0.94;P=0.029）, B*48（OR=0.15,95% CI=0.03～0.72;P=0.007）,CW*08（OR=0.32,95% CI=0.15～0.69;P=0.003）and a higher allele frequency of CW*15（OR=5.11,95% CI=0.63～40.90;P=0.024）compared with Hp negative controls.Our results indicated that the polymorphisms of HLA typeⅠis involved in the genetic susceptibility of Hp infection in Linqu County,while the polymorphisms of HLA typeⅡ may have no relationship with the genetic susceptibility of Hp infection.It was shown that among the alleles of HLA typeⅠ,CW*15might be a susceptible gene of Hp infection while A*02,B*48 and CW*08might be protective genes.     

中国南方汉族群体MPSI型Kpn I酶切位点的遗传多态性

为研究中国汉族群体IDUA 基因Kpn I 酶切位点的遗传多态性以及该位点等位基因片段传递的规律, 采用PCR-RFLP技术, 对162例无血缘关系的健康中国汉人的324条 染色体进行检测,另又对5个家系16位成员进行同样的检测,然后用χ2检验进行统计学处理。结果表明,等位基因A1 频率为0.17,等位基因A2 频率为0.83,杂合率为29%;A1 、A2 的传递规律与理论上预计的完全符合。认为中国汉族群体IDUA 基因 Kpn I 酶切位点也具有遗传多态性, 并且与国外报道的无显著性差异;A1、A2 在世代中的传递完全符合孟德尔遗传规律。 Abstract:To investigate the genetic polymorphism of the Kpn I site in the α-L-iduronidase(IDUA) gene from a Han population in southern China and to study the mode of transmission of alleles, PCR-RFLP was used to analyze 324 chromosomes from 162 Chinese unrelated healthy Han individuals, and the analysis of the genotypes of 16 members in five families. To compare the frequencies and heterzygosity between Chinese Han population and Caucasians in Western by using χ2test. The frequency of allele 1 (450bp) was 0.17,allele 2 (390 plus 60 bp) 0.83, the heterozygosity was 29%.The genotypes of each member of all families detected was completely agreement with the theorical assessment. The locus of Kpn I in the IDUAgene from Han population has polymorphism. There is no significant difference between Chinese Han population and Caucasians in Western countries. The transmission of alleles was agreement with the Mendelian genetic law.     

The Characterization and Geographical Distribution of the Genes Responsible for Vernalization Requirement in Chinese Bread Wheat

The frequency and distribution of the major vernalization requirement genes and their effects on growth habits were studied. Of the 551 bread wheat genotypes tested, seven allelic combinations of the three Vrn-1 genes were found to be responsible for the spring habit, three for the facultative habit and one for the winter habit. The three Vrn-1 genes behaved additiveiy with the dominant allele of Vrn-A1 exerting the strongest effect. The allele combinations of the facultative genotypes and the discovery of spring genotypes with ＂winter＂ allele of Vrn-1 implied the presence of as yet unidentified alleles/genes for vernalization response. The dominant alleles of the three Vrn-1 genes were found in all ten ecological regions where wheat is cultivated in China, with Vrn-D1 as the most common allele in nine and Vrn-A1 in one. The combination of vrn-A1vrn-B1Vrn-D1 was the predominant genotype in seven of the regions. Compared with landraces, improved varieties contain a higher proportion of the spring type. This was attributed by a higher frequency of the dominant Vrn-A1 and Vrn-B1 alleles in the latter, Correlations between Vrn-1 allelic constitutions and heading date, spike length, plant type as well as cold tolerance were established.     

中国傣族、景颇族人群中与艾滋病相关的CCR5△32、CCR2b-64I、SDF1-3′A等位基因多态性分布

为了调查HIV-1感染相关的等位基因CCR5△32、CCR2b-64I、SDF1-3′A在我国云南省德宏州傣族景颇族人群中的频率和多态性分布,此课题以101例傣族和113例景颇族人群为研究对象,应用PCR、PCR-RFLP(聚合酶链反应-限制性片段长度多态性)分析方法进行检测,计算突变基因频率;并对其群体分布、性别分布进行统计学分析。结果表明,中国傣族景颇族人群中未发现CCR5△32等位基因突变;傣族CCR2b-64I、SDF1-3′A基因突变频率分别为0.2130和0.2030,景颇族CCR2b-64I和SDF1-3′A基因突变频率分别为0.1637和0.1770;与中国汉族人群相比较,傣族和景颇族中SDF1-3′A突变频率较低（P值分别为0.0322和0.0021）;两个民族的CCR2b-64I和SDF1-3′A等位基因群体分布符合Hardy-Weinberg平衡,在性别之间分布无显著差异。中国傣族景颇族人群的CCR2b-64I等位基因的突变频率与汉族人相似,SDF1-3′A等位基因的突变频率比汉族人低,此两种突变基因在艾滋病发病过程中的影响值得进一步研究。由于未发现CCR5△32基因突变,中国傣族景颇族人群对HIV-1感染可能有较大的遗传易感性。 Abstract:The purpose of the work is to investigate the frequencies and polymorphisms of HIV-1 resistant CCR5delta32,CCR2b-64I,SDF1-3′A alleles in Chinese Dai and Chingpaw populations.Whole blood samples from 101 Dai subjects and 113 Chingpaw were collected randomly and their genomic DNA were extracted with QIAgen Blood Kits.Allelic frequencies were identified by PCR-RFLP analysis.Allelic polymorphisms in Dai population or Chingpaw population and both sexes in the samples were analyzed by χ2 test.The frequencies of CCR5delta32,CCR2b-64I,SDF1-3′A alleles in Dai population were 0.0000,0.2130,0.2030,respectively;The frequencies of CCR5delta32,CCR2b-64I,SDF1-3′A alleles in Chingpaw population were 0.000,0.1637,0.1770,respectively.Distributions of the CCR2b-64I,SDF1-3′A alleles among the both populations were in accordance with Hardy-Weinberg equilibrium.No statistical difference was found in the allelic frequencies of both CCR2b-64I and SDF1-3′A between male and female individuals.The frequencies of CCR5delta32,CCR2b-64I alleles in Chinese Dai and Chingpaw populations are similar to that in Chinese Han population,while the frequency of SDF1-3′A allele in Chinese Dai and Chingpaw populations are lower in contrast to that in Chinese Han population.The genotyping and polymorphism of CCR5delta32,CCR2b-64I,SDF1-3′A alleles in Chinese Dai and Chingpaw populations of Yunnan Province are the first time studied in China.The significance of the three mutant alleles conferring genetic resistance to HIV-1 and AIDS progression remains to be clarified.     

中国傣族、景颇族人群中与艾滋病相关的CCR5△32、CCR2b-64I、SDF1-3′A等位基因多态性分布

为了调查HIV-1感染相关的等位基因CCR5△32、CCR2b-64I、SDF1-3′A在我国云南省德宏州傣族景颇族人群中的频率和多态性分布,此课题以101例傣族和113例景颇族人群为研究对象,应用PCR、PCR-RFLP(聚合酶链反应-限制性片段长度多态性)分析方法进行检测,计算突变基因频率;并对其群体分布、性别分布进行统计学分析。结果表明,中国傣族景颇族人群中未发现CCR5△32等位基因突变;傣族CCR2b-64I、SDF1-3′A基因突变频率分别为0.2130和0.2030,景颇族CCR2b-64I和SDF1-3′A基因突变频率分别为0.1637和0.1770;与中国汉族人群相比较,傣族和景颇族中SDF1-3′A突变频率较低（P值分别为0.0322和0.0021）;两个民族的CCR2b-64I和SDF1-3′A等位基因群体分布符合Hardy-Weinberg平衡,在性别之间分布无显著差异。中国傣族景颇族人群的CCR2b-64I等位基因的突变频率与汉族人相似,SDF1-3′A等位基因的突变频率比汉族人低,此两种突变基因在艾滋病发病过程中的影响值得进一步研究。由于未发现CCR5△32基因突变,中国傣族景颇族人群对HIV-1感染可能有较大的遗传易感性。 Abstract:The purpose of the work is to investigate the frequencies and polymorphisms of HIV-1 resistant CCR5delta32,CCR2b-64I,SDF1-3′A alleles in Chinese Dai and Chingpaw populations.Whole blood samples from 101 Dai subjects and 113 Chingpaw were collected randomly and their genomic DNA were extracted with QIAgen Blood Kits.Allelic frequencies were identified by PCR-RFLP analysis.Allelic polymorphisms in Dai population or Chingpaw population and both sexes in the samples were analyzed by χ2 test.The frequencies of CCR5delta32,CCR2b-64I,SDF1-3′A alleles in Dai population were 0.0000,0.2130,0.2030,respectively;The frequencies of CCR5delta32,CCR2b-64I,SDF1-3′A alleles in Chingpaw population were 0.000,0.1637,0.1770,respectively.Distributions of the CCR2b-64I,SDF1-3′A alleles among the both populations were in accordance with Hardy-Weinberg equilibrium.No statistical difference was found in the allelic frequencies of both CCR2b-64I and SDF1-3′A between male and female individuals.The frequencies of CCR5delta32,CCR2b-64I alleles in Chinese Dai and Chingpaw populations are similar to that in Chinese Han population,while the frequency of SDF1-3′A allele in Chinese Dai and Chingpaw populations are lower in contrast to that in Chinese Han population.The genotyping and polymorphism of CCR5delta32,CCR2b-64I,SDF1-3′A alleles in Chinese Dai and Chingpaw populations of Yunnan Province are the first time studied in China.The significance of the three mutant alleles conferring genetic resistance to HIV-1 and AIDS progression remains to be clarified.     

Developing a one-step triplet-repeat primed PCR assay for diagnosing myotonic dystrophy

正Myotonic dystrophy type 1 (DM1),or Steiner's disease,is an autosomal dominant disorder caused by the expansion of unstable trinucleotide repeats (CTG) in the 3' untranslated region of the myotonic dystrophy protein kinase gene (DMPK) (Brook et al.,1992;Mahadevan et al.,1992).The number of CTG repeats observed in normal individuals is in a range of 5-34,while the individuals with 35-49 CTG repeats are usually asymptomatic but at risk of     

我国葫芦科植物离体培养研究进展

葫芦科植物包括多种瓜类蔬菜,对其进行离体培养研究具有重要的理论和实践意义。综述了国内在葫芦科植物器官培养、体细胞胚胎发生、花药培养、原生质体培养和体细胞杂交及离体遗传转化等方面取得的研究进展,并对葫芦科植物离体培养、遗传转化与育种的前景作了展望。     

我国葫芦科植物离体培养研究进展

葫芦科植物包括多种瓜类蔬菜,对其进行离体培养研究具有重要的理论和实践意义.综述了国内在葫芦科植物器官培养、体细胞胚胎发生、花药培养、原生质体培养和体细胞杂交及离体遗传转化等方面取得的研究进展,并对葫芦科植物离体培养、遗传转化与育种的前景作了展望.     

国内双歧杆菌制剂预防小儿继发性腹泻临床疗效的Meta分析

目的系统评价国内双歧杆菌制剂临床预防小儿继发性腹泻的效果。方法按照系统评价的要求检索CBMd isc、VIP、CNK I以及万方数据库等,获得18篇符合纳入标准的文献,共计患儿4050例,对其进行M eta分析,并评价M eta分析结果的稳定性和发表偏倚。结果异质性检验χ^2=34.60,P=0.007〈0.05,采用随机效应模型进行M eta分析,合并RR=0.41,95%C I为0.35～0.49,总体效应检验,Z=10.39,P〈0.00001,差异具有非常显著性,固定效应模型RR值和95%C I与随机效应模型完全一致,剔除小样本报道后的合并RR=0.42,95%C I为0.35～0.50,与剔除前的结果基本一致,且本研究的发表偏倚得到了很好地控制。结论从现有的临床证据来看,双歧杆菌制剂能降低小儿继发性腹泻的发生率,对预防小儿继发性腹泻起到了满意的效果。     

右美托咪啶用于SICU镇静时血流动力学效应与年龄的关系

目的：以心率（HR）、心指数（CI）、体循环阻力（SVR）作为效应指标,明确右美托咪啶（Dex）用于SICU 镇静时年龄和血流动 力学效应的关系。方法：选择2014 年3 月~7 月间在我院SICU 接受普胸或者普外科手术后需要短期镇静患者38 例,各年龄段分 布相对均匀。在病人术后Ramsay评分≤ 3 分时给予右旋美托咪啶6.0 ug/kg/h,连续静脉输注10 min 后停药,应用脉搏指示连续 心输出量监测技术(PICCO)记录用药前及用药后3 min、5 min、8 min、10 min、15 min、20 min、30 min、45 min、60 min、90 min、120 min 的11 个时间点的HR、CI 和SVR。结果：HR、CI 和SVR 的EMAX 随着年龄的增加而增大,可以通过数学模型表示：E= （P<0.05）。结论：右美托咪啶用于SICU 镇静时,患者HR、CI和SVR的EMAX 呈 年龄依赖性变化。     

我国蝴蝶产业发展中亟待解决的几个问题

本文简略介绍了我国目前蝴蝶产业的背景情况和发展现状,着重阐述了该产业发展中亟待解决的目标与思路、政策与法律、科研与技术、人才与培养等一系列问题,并针地性提出了相应解决意见。     

Studies of in vivo mutations in rpsL transgene in UVB-irradiated epidermis of XPA-deficient mice

We have established xeroderma pigmentosum group A (XPA) gene-knockout mice with nucleotide excision repair (NER) deficiency, which rapidly developed skin tumors when exposed to a low dose of chronic UV like XP-A patients, confirming that the NER process plays an important role in preventing UVB-induced skin cancer. To examine the in vivo mutation in the UVB-irradiated epidermis, we established XPA (−/−), (+/−) and (+/+) mice carrying the Escherichia coli rpsL transgene with which the mutation frequencies and spectra in the UVB-irradiated epidermal tissue can be examined conveniently. The XPA (−/−) mice showed a higher frequency of UVB-induced mutation in the rpsL transgene with a low dose (150 J/m²) of UVB-irradiation than the XPA (+/−) and (+/+) mice, while, at a high dose (900 J/m²) they showed almost the same frequency of mutation as the XPA (+/−) and (+/+) mice, probably because of cell death in the epidermis of the XPA (−/−) mice. However, CC→TT tandem transition, a hallmark of UV-induced mutation, was detected at higher frequency in the XPA (−/−) mice than the XPA (+/−) and (+/+) mice at both doses of UVB. This rpsL/XPA mouse system will be useful for further analyzing the role of NER in the mutagenesis and carcinogenesis induced by various carcinogens.     

细胞分裂素对植物衰老的延缓作用

细胞分裂素是一类重要的植物激素,它可在一定程度上延缓植物的衰老。主要从3个方面综述了细胞分裂素与植物衰老之间的关系,即:(1)植物衰老过程中内源细胞分裂素含量变化;(2)外源细胞分裂素的影响;(3)转入与细胞分裂素的合成、降解相关的基因对植物衰老产生的影响。此外,还从细胞分裂素与糖、与脂质氧化反应以及与其它植物激素的关系方面探讨了细胞分裂素在延缓植物衰老中的作用机理。     

Application of in vitro techniques in mutation breeding of chrysanthemum

Rooted cuttings of Chrysanthemum morifolium cv. Maghi, a small flowered, late blooming cultivar, were treated with different doses of gamma rays. Somatic mutations in flower colour (light mauve, white, light yellow and dark yellow) and chlorophyll variegation in leaves were detected as chimeras in treated populations. Attempts were made to standardize a microtechnique for plant regeneration from mutated tissues of stem node, stem internode, shoot tip and ray floret. All these explants were cultured on Murashige and Skoog's medium with 3% sucrose, 0.8% agar and different concentrations and combinations of growth regulators. Plant regeneration was successful from all of the mutated tissues. Plants with chlorophyll variegation in leaves and two new flower colours (light mauve and white) were isolated in pure form with 64% and 100% efficiency of mutant recovery, respectively. Attempts are being made to use this technique to establish new varieties from chimeric tissues to meet the increasing demand of the floriculture trade.     

Role of Telomerase in Reactivation of Macrophage Nuclei in Heterokaryons

It was shown that the duration of stay of macrophages in the peritoneal cavity of mice and method of their isolation did not affect markedly their capacity for resumption of DNA synthesis in heterokaryons. This means that mouse macrophage undergo such changes during differentiation that reactivation of DNA synthesis in their nuclei is only possible after interaction of telomeres with telomerase, since it was already shown that telomerase was involved in reactivation of DNA synthesis in the macrophage nuclei. The results of experiments did not reveal differences in the length of telomeres in mouse macrophages and other somatic cells. This could depend on the significant length of mouse telomeres and, as a result, their shortening, sufficient for the inhibition of proliferation, is beyond the limits of sensitivity of the current methods. It is also possible that changes in DNA properties in the macrophages occurring during their differentiation depend on changes in the conformation of the telomere complex in these cells. Testing of this suggestion is relevant with respect to recent data that cell hybridization, specifically in the form of heterokaryons, may be essential in realization of the therapeutic effect caused by the introduction of cells during cell therapy.