microRNA在小鼠乳腺不同发育时期差异表达谱及作用

microRNA是一类大小约22个核苷酸的非编码RNA分子,是一种广泛存在的对基因表达进行微调的分子。microRNA可以通过与靶基因mRNA的特定位点结合,抑制该蛋白的合成或诱导该mRNA的降解,从而参与基因的表达调控。一般来源于染色体的非编码区域,由大约70个核苷酸大小的可形成发夹结构的前体经Dicer酶加工而来。这类小RNA在表达上具有组织和时间的特异性,是调节其他功能基因表达的重要调控分子,在生物的生长发育过程中发挥着重要作用。因此,虽然microRNA的研究仅有很短的历史,但已成为基因表达调控研究的热点领域。以中国昆明小鼠不同发育时期的乳腺组织为实验材料,应用芯片技术及荧光定量PCR技术,分析发育不同时期的乳腺组织microRNA差异表达图谱。本文研究发现microRNA在乳腺不同的发育时期表达图谱不同;与青春期、退化期比较,妊娠期、哺乳期有十余种microRNAs表达上调,20余种microRNAs表达下调;microRNAs在乳腺发育和泌乳周期中发挥重要的作用。     

Development and Application of Microsatellites in Candidate Genes Related to Wood Properties in the Chinese White Poplar (Populus tomentosa Carr.)

Gene-derived simple sequence repeats (genic SSRs), also known as functional markers, are often preferred over random genomic markers because they represent variation in gene coding and/or regulatory regions. We characterized 544 genic SSR loci derived from 138 candidate genes involved in wood formation, distributed throughout the genome of Populus tomentosa, a key ecological and cultivated wood production species. Of these SSRs, three-quarters were located in the promoter or intron regions, and dinucleotide (59.7%) and trinucleotide repeat motifs (26.5%) predominated. By screening 15 wild P. tomentosa ecotypes, we identified 188 polymorphic genic SSRs with 861 alleles, 2–7 alleles for each marker. Transferability analysis of 30 random genic SSRs, testing whether these SSRs work in 26 genotypes of five genus Populus sections (outgroup, Salix matsudana), showed that 72% of the SSRs could be amplified in Turanga and 100% could be amplified in Leuce. Based on genotyping of these 26 genotypes, a neighbour-joining analysis showed the expected six phylogenetic groupings. In silico analysis of SSR variation in 220 sequences that are homologous between P. tomentosa and Populus trichocarpa suggested that genic SSR variations between relatives were predominantly affected by repeat motif variations or flanking sequence mutations. Inheritance tests and single-marker associations demonstrated the power of genic SSRs in family-based linkage mapping and candidate gene-based association studies, as well as marker-assisted selection and comparative genomic studies of P. tomentosa and related species.     

Design, synthesis, and pharmacological evaluation of benzamide derivatives as glucokinase activators

A series of benzamide derivatives were assembled by using the privileged-fragment-merging (PFM) strategy and their SAR studies as glucokinase activators were described. Compounds 5 and 16b were identified having a suitable balance of potency and activation profile. They showed EC(50) values of 28.3 and 44.8 nM, and activation folds of 2.4 and 2.2, respectively. However, both compounds displayed a minor reduction in plasma glucose levels on imprinting control region (ICR) mice. Unfavorable pharmacokinetic profiles (PK) were also observed on these two compounds.     

小叶杨DREB同源基因内SSR的发现及群体结构分析

利用基因特异的PCR引物从小叶杨(Populus simonii)经干旱胁迫后构建的cDNA文库中扩增得到长度为671 bp的PsDREB cDNA克隆。该基因内部含有完整的且大小为543 bp的开放阅读框, 可编码181个氨基酸残基。在此基础上, 对36株小叶杨基因型个体的DREB基因进行了克隆和序列分析, 发现其内部存在以CAC为基本单位的4次(A)、5次(B)、7次(C)、8次(D)、9次(E)、10次(F)和11次(G)7种类型的简单重复序列(SSR)。以该重复序列为扩增对象设计引物, 对我国11个省16个群体528株小叶杨进行了群体遗传结构分析。结果表明, 在检测群体中各位点等位基因频率大小顺序依次为: D＞C＞F＞E＞A＞G＞B; 平均有效等位基因数为3.167 0, 平均观察和期望杂合度分别为0.468 5和0.531 5, 且在多数群体中存在一定程度的近交效应和显著偏离Hardy-Weinberg平衡; 而Ewens-Watterson中立性检验表明, 除山西宁武、辽宁朝阳和河南伊川外, 其它多数群体均属于中立性选择。研究结果将为利用候选基因内SSR标记来评价林木育种资源的遗传多样性以及保护和利用这些资源提供科学的理论依据。     

Mapping of two white stem genes in tetraploid common tobacco (Nicotiana tabacum L.)

Leaf color is an indicator of chlorophyll (Chl) level, and isolating leaf color mutants can facilitate the understanding of Chl metabolism regulation. Here, we describe an ethyl methanesulfonate-induced light color mutant white stem 1 (ws1) in common tobacco (Nicotiana tabacum L.) that shows a phenotype highly similar to burley tobacco (Nicotiana tabacum L.), a type of air-cured tobacco that has light-colored leaves with white veins. Compared with the wild type, the light green stem of ws1 gradually became pale white along with growth, while ws1 leaves lost green color rapidly, which was positively correlated with the decline of Chl levels. A series of genetic analyses indicated that the ws1 mutant phenotype was controlled by two recessive nuclear genes ws1a and ws1b which were preliminarily mapped to the intervals of tobacco simple sequence repeat markers linkage groups 5 and 24 using the BC1F2 populations, respectively. The allelism test further revealed that the same two genes controlled the burley character in burley tobacco. Based on the Chl-deficient phenotype of ws1 and the locations of the two genes, we hypothesized that ws1a and ws1b were paralogs of each other probably originated from the ancestral species N. sylvestris and N. tomentosiformis, respectively. Both genes might share similar biological functions and expression patterns, and play key roles in the regulation of Chl biosynthesis. These results laid a solid foundation for marker-assisted selection breeding and gene function analysis of the burley character in tobacco.     

Design,synthesis, and pharmacological evaluation of N-(4-mono and 4,5-disubstituted thiazol-2-yl)-2-aryl-3-(tetrahydro-2H-pyran-4-yl)propanamides as glucokinase activators

A series of N-thiazole substituted arylacetamides were designed on the basis of metabolic mechanism of the aminothiazole fragment as glucokinase (GK) activators for the treatment of type 2 diabetes. Instead of introducing a substituent to block the metabolic sensitive C-5 position on the thiazole core directly, a wide variety of C-4 or both C-4 and C-5 substitutions were explored. Compound R-9k bearing an iso-propyl group as the C-4 substituent was found possessing the highest GK activation potency with an EC₅₀ of 0.026 μM. This compound significantly increased both glucose uptake and glycogen synthesis in rat primary cultured hepatocytes. Moreover, single oral administration of compound R-9k exerted significant reduction of blood glucose levels in both ICR and ob/ob mice. These promising results indicated that compound R-9k is a potent orally active GK activator, and is warranted for further investigation as a new anti-diabetic treatment.