Speciation- induced heritable cytosine methylation changes in polyploid wheat

To study possible epigenetic changes accompanying polyploid speciation, genomic DNA from natural polyploid wheats and their putative diploid progenitors were digested with a pair of isoschizomers Hpa II / Msp I and hybridized to 21 different types of low-copy DNA sequences. It was found that cytosine methylation changes were abundant in natural polyploid wheats after their speciation. The hybridization of the same set of sequences to a synthetic hexaploid wheat along with its parental lines indicated that the extensive DNA methylation changes already existed in the early generations (S5, S6 and Sy) of this plant. Moreover, the high similarity of the changed restriction fragment length polymorphism (RFLP) patterns among three randomly chosen individual plants suggested that the methylation changes occurred even earlier, and/or were of a nonrandom nature. The changed patterns were stably inherited in the three successive selfed generations. Though methylation changes are probably a genome-wide occurrence, they appeared to be confined to the specific types of DNA sequences. The possible implications of the rapid and extensive cytosine methylation changes for several attributes of allopolyploid genome evolution, such as genetic diploidization and gene diversification, are discussed .     

两种代表性富硒植物硒在实验性高脂血症大鼠组织累积分布研究

对比研究富硒大蒜和富硒绿羽中的植物硒在实验性高脂血症大鼠主要组织的累积分布情况,为安全利用富硒植物硒资源提供理论依据.采用高脂膳食诱导大鼠高脂血症,分别在大鼠饲喂高脂饲料同时(预防组)和高脂血症形成以后(治疗组)以灌胃的方式给予富硒植物悬浊液,实验期3个月,实验结束后宰杀大鼠,测定大鼠肝、肾、脾、红细胞和血浆含硒量.总体来看,富硒绿羽组大鼠肝脏和肾脏含硒量显著高于富硒大蒜组,富硒绿羽组大鼠脾脏和红细胞硒水平低于富硒大蒜组;摄入不同植物硒的治疗组和预防组在组织硒累积幅度和分布上有一些变化.硒在不同组织内分布受摄入硒形态、给药时间和给药期的影响,富硒大蒜比富硒绿羽具有更高的安全性.     

色谱联用技术在环境和生物样品中痕量超痕量元素形态分析研究进展

随着分析科学的不断发展,常用的元素分析方法,如光谱技术(AES,AFS)和质谱等已不能满足环境和生物样品中痕量、超痕量元素的赋存形态分析。以色谱联用技术为代表的元素形态分析测试技术(如液相色谱-原子光谱联用、色谱-电感耦合等离子质谱联用、毛细管电泳-电喷雾离子化质谱联用技术等)已成为国内外研究的热点。本文扼要的介绍了近年来国内外在环境和生物样品中痕量、超痕量元素砷、硒、汞形态分析的色谱联用技术研究进展,并侧重于样品前处理方法、痕量或超痕量元素的形态分析技术。