Aplysia californica: analysis of nuclear DNA in individual nuclei of giant neurons

The nuclei of the giant neurons of the marine mollusk Aplysia californica can contain more than 0.2 microgram of DNA. This is more than 200,000 times as much DNA as the haploid amount found in Aplysia sperm. On the basis of nuclear DNA content, the giant neurons R-2, P-1, and L-6 of adult animals can each be divided into at least two populations. The mean DNA content of these two populations (0.067 and 0.131 microgram of DNA) are approximately related by a factor of 2. This suggests that much and perhaps all of the genome replicates repeatedly (up to 16 times) during the growth and development of these neurons and that each replication is synchronous. The enormous amount of DNA in these cells opens up the possibility of characterizing the DNA and other constituents of chromatin from individual but phenotypically different neurons.     

Regulation of B cell tolerance by the lupus susceptibility gene Ly108

The susceptibility locus for the autoimmune disease lupus on murine chromosome 1, Sle1z/Sle1bz, and the orthologous human locus are associated with production of autoantibody to chromatin. We report that the presence of Sle1z/Sle1bz impairs B cell anergy, receptor revision, and deletion. Members of the SLAM costimulatory molecule family constitute prime candidates for Sle1bz, among which the Ly108.1 isoform of the Ly108 gene was most highly expressed in immature B cells from lupus-prone B6.Sle1z mice. The normal Ly108.2 allele, but not the lupus-associated Ly108.1 allele, was found to sensitize immature B cells to deletion and RAG reexpression. As a potential regulator of tolerance checkpoints, Ly108 may censor self-reactive B cells, hence safeguarding against autoimmunity.     

猪个体基因杂合度对胴体性状的影响

134头F2 代杂种猪 (大白×梅山 )在平均体重 88kg时屠宰。用分布在 1、 2和 6号染色体上的 2 4个微卫星座位估计个体基因杂合度 ,分析 1 3个胴体性状随个体基因杂合度增加的变化规律。结果表明 ,屠宰率、胴体重、花油率、板油率、腰部膘厚、胸部膘厚、肩部膘厚、皮率、瘦肉率和脂肪率在各个体基因杂合度 (hi)水平间无显著差异(P >0 0 5 )。胴体长、眼肌面积和骨率在各hi 水平间差异显著 ,hi 小于 0 6时皮率与骨率随hi 增加逐渐降低 ,大于 0 6时随hi 增加而增加 ,而瘦肉率的变化趋势与皮率和骨率恰恰相反。眼肌面积随hi 增加而上下波动。胴体长则随hi 水平的增加而逐渐降低。hi 在 0 6 0～ 0 6 5时 ,胴体长和眼肌面积性状值较高 ,而骨率达最低值 ,表明在生产中可以将个体基因杂合度控制在 0 6 0～ 0 6 5 ,从而综合利用这些性状 ,以提高猪的胴体生产性能     

猪个体基因杂合度对肉质的影响

用分布在1，2和6号染色体上的24个微卫星座位估计140头F2杂种猪的个体基因杂合度，并测定了这些个体的系水力（WHC），失水率（WLR），肌苷含量（HR），肌内脂肪（IMF），蛋白质含量，股二头肌pH(pH(B))。背最长肌pH(pH(L))，复合肌pH(C))8个肉质性状，并分析这些性状随个体基因杂合度增加的变化规律。结果表明，WHC和HR在个体基因杂合度超过0.5时随杂合度增加而降低；WLR在个体基因杂合度小于0.65时随杂合度增加而增加，之后随杂合度增加而降低；随个体基因杂合度的增加，蛋白质含量的变化不显；IMF在个体基因杂合度小于0.65时呈不规则变化。之后随个体基因杂合度增加而增加；pH(B),pH(L)和pH(C)随个体基因杂合度的增加变化趋势和幅度不明显。     

Fluorochrome-labeled deoxyribonuclease: specific stain for cell nuclei

Nuclei of cells in tissue culture may be stained with deoxyribonuclease labeled with fluoresceitn isothiocyatnate; this is a simple, rapid, and specific process which is useful in localizing DNA in situ.     

玉米MIR基因转录起始位点预测方法研究

MIR基因是由RNA聚合酶Ⅱ指导转录的,其核心启动子区域具有保守的顺式作用因子,主要是基因-30的TATA和-75的CAAT的特征,开发出一种转录起始位点的预测方法.利用该预测方法,对用深度测序技术获得的玉米胚萌发阶段杂种优势相关miRNA的编码MIR基因进行了顺式作用元件分析,得到了其转录起始位点和启动子区序列特征.同时,利用5'RACE技术对预测的一些转录起始位点进行了验证,证明该预测方法是可行的.     

多胺代谢相关基因在小鼠子宫内膜细胞中的调节

利用鸟氨酸脱羧酶(ODC)siRNA干涉、ODC过表达、添加特异性ODC抑制剂二氟甲基鸟氨酸(DFMO)处理小鼠子宫内膜上皮细胞和基质细胞,采用实时定量PCR对多胺代谢相关酶类mRNA水平进行检测。结果显示:在子宫内膜上皮和基质细胞中,ODC siRNA转染后可导致SSAT mRNA水平下降为对照组的71.78%和54.36%(P<0.01),SAMDC mRNA水平上升为对照组的1.666 6倍和3.036 6倍(P<0.01);ODC过表达造成SSAT水平为对照组的1.921 4和2.852 7倍(P<0.01),AZⅠmRNA水平为对照组的1.962 1和3.073 8倍(P<0.01);利用DFMO处理体外分离的上皮细胞和基质细胞,SSAT mRNA水平为对照组的1.626 7和1.773 3倍(P<0.01),SAMDC mRNA水平为对照组的1.630 0和1.730 0倍(P<0.01),AZⅠmRNA水平为对照组的71.00%和76.67%(P<0.01);DFMO处理后上皮细胞和基质细胞数目(31.00±3.00和43.67±7.51)和活力(0.26±0.03和0.36±0.05)都显著下...