Irf6 is a key determinant of the keratinocyte proliferation-differentiation switch

The epidermis is a highly organized structure, the integrity of which is central to the protection of an organism. Development and subsequent maintenance of this tissue depends critically on the intricate balance between proliferation and differentiation of a resident stem cell population; however, the signals controlling the proliferation-differentiation switch in vivo remain elusive. Here, we show that mice carrying a homozygous missense mutation in interferon regulatory factor 6 (Irf6), the homolog of the gene mutated in the human congenital disorders Van der Woude syndrome and popliteal pterygium syndrome, have a hyperproliferative epidermis that fails to undergo terminal differentiation, resulting in soft tissue fusions. We further demonstrate that mice that are compound heterozygotes for mutations in Irf6 and the gene encoding the cell cycle regulator protein stratifin (Sfn; also known as 14-3-3sigma) show similar defects of keratinizing epithelia. Our results indicate that Irf6 is a key determinant of the keratinocyte proliferation-differentiation switch and that Irf6 and Sfn interact genetically in this process.     

Topological domains in mammalian genomes identified by analysis of chromatin interactions

The spatial organization of the genome is intimately linked to its biological function, yet our understanding of higher order genomic structure is coarse, fragmented and incomplete. In the nucleus of eukaryotic cells, interphase chromosomes occupy distinct chromosome territories, and numerous models have been proposed for how chromosomes fold within chromosome territories. These models, however, provide only few mechanistic details about the relationship between higher order chromatin structure and genome function. Recent advances in genomic technologies have led to rapid advances in the study of three-dimensional genome organization. In particular, Hi-C has been introduced as a method for identifying higher order chromatin interactions genome wide. Here we investigate the three-dimensional organization of the human and mouse genomes in embryonic stem cells and terminally differentiated cell types at unprecedented resolution. We identify large, megabase-sized local chromatin interaction domains, which we term 'topological domains', as a pervasive structural feature of the genome organization. These domains correlate with regions of the genome that constrain the spread of heterochromatin. The domains are stable across different cell types and highly conserved across species, indicating that topological domains are an inherent property of mammalian genomes. Finally, we find that the boundaries of topological domains are enriched for the insulator binding protein CTCF, housekeeping genes, transfer RNAs and short interspersed element (SINE) retrotransposons, indicating that these factors may have a role in establishing the topological domain structure of the genome.     

乌桕脂及制取的类可可脂的稳定性初步研究

桕脂及制取的类可可脂的稳定性是一个急待解决的问题 ,本文就此方面作了初步研究 .1　材料与方法1 .1　实验材料(1 )乌桕脂 (皮油 ) :购于湖北罗田 ,粗桕脂酸价ＡＶｋＯＨ=6.69ｍｇ/ｇ ,过氧化值ＰＯＶ =8.49ｍｍｏｌ/ｋｇ ,经脱酸、脱水、脱臭后精炼桕脂ＡＶｋＯＨ=0 .3 7ｍｇ/ｇ ,ＰＯＶ =1 .3 8ｍｍｏｌ/ｋｇ .(2 )类可可脂 ,按文献 [1 ]方法制得 .　　 (3 )油脂抗氧化剂 :二丁基羟基甲苯 (ＢＨＴ)市场购买 ,茶多酚 (ＴＰＥ)按文献 [2 ]方法制得 .1 .2　实验方法　　 (1 )抗氧化试验 :按文献 [2 ]方法 ,取定量的实验油脂 ,60℃熔解 ,称取…     

华南主要蔬菜抗氧化作用研究

选用华南地区52种主要蔬菜，分析其原汁的总抗氧化能力、清除自由基能力、SOD活性和维生素C含量。结果表明，蔬菜类型和品种不同，其原汁的抗氧化作用差异较大，在所比较的11种蔬菜类型中，以野生蔬菜类原汁的抗氧化活性最强，薯芋类和根菜类活性最低，一部分蔬菜的抗氧化作用与其SOD活性呈现一致性，有些蔬菜的则与其维生素C含量呈现一致性，蔬菜抗氧化作用的机制既可能表现为以SOD为物质基础的酶促反应形式，也可能是以维生素C为物质基础的非酶反应形式。     

Association analyses of 249,796 individuals reveal 18 new loci associated with body mass index

Obesity is globally prevalent and highly heritable, but its underlying genetic factors remain largely elusive. To identify genetic loci for obesity susceptibility, we examined associations between body mass index and ～ 2.8 million SNPs in up to 123,865 individuals with targeted follow up of 42 SNPs in up to 125,931 additional individuals. We confirmed 14 known obesity susceptibility loci and identified 18 new loci associated with body mass index (P < 5 × 10??), one of which includes a copy number variant near GPRC5B. Some loci (at MC4R, POMC, SH2B1 and BDNF) map near key hypothalamic regulators of energy balance, and one of these loci is near GIPR, an incretin receptor. Furthermore, genes in other newly associated loci may provide new insights into human body weight regulation.     

Ecology. Global amphibian population declines

The decline and disappearance of relatively undisturbed populations of amphibians in several high-altitude regions since the 1970s suggests that they may have suffered a global decline, perhaps with a common cause or causes. Houlahan et al. examined means of trends for 936 amphibian populations and concluded that global declines began in the late 1950s, peaked in the 1960s, and have continued at a reduced rate since. Here we re-analyse their data using a method that accounts for the sampling of different populations over different time periods, and find evidence of a mean global decline in monitored populations only in the 1990s. However it is calculated, the global mean not only masks substantial spatial and temporal variation in population trends and sampling effort, but also fails to distinguish between a global decline with global causes and the cumulative effects of local declines with local causes.     

利用毛细管电泳仪测定B 族维生素含量最佳电泳条件的探讨

探讨毛细管电泳对Ｂ族维生素的分离分析的最佳电泳条件,结果表明：胶束电动力学毛细管色谱是分离分析Ｂ族维生素的一种有效的毛细管电泳操作模式;不同缓冲液及其ＰＨ对分离造果影响很大,１００ｍｍｏｌ／Ｌ硼酸钠缓冲液（ＰＨ８．５）比较适合Ｂ族维生素的分离分析;毛细管温度、运行电压对分离也有较大影响,在３５ｃｍ＊５０μｍ未涂渍石英毛细管条件下,采用ＰＨ８．５,附加５０ｍｍｏｌ／Ｌ ＳＤＳ对分离也有较大影响,在３