Cohesin mediates chromatin interactions that regulate mammalian β-globin expression

The β-globin locus undergoes dynamic chromatin interaction changes in differentiating erythroid cells that are thought to be important for proper globin gene expression. However, the underlying mechanisms are unclear. The CCCTC-binding factor, CTCF, binds to the insulator elements at the 5' and 3' boundaries of the locus, but these sites were shown to be dispensable for globin gene activation. We found that, upon induction of differentiation, cohesin and the cohesin loading factor Nipped-B-like (Nipbl) bind to the locus control region (LCR) at the CTCF insulator and distal enhancer regions as well as at the specific target globin gene that undergoes activation upon differentiation. Nipbl-dependent cohesin binding is critical for long-range chromatin interactions, both between the CTCF insulator elements and between the LCR distal enhancer and the target gene. We show that the latter interaction is important for globin gene expression in vivo and in vitro. Furthermore, the results indicate that such cohesin-mediated chromatin interactions associated with gene regulation are sensitive to the partial reduction of Nipbl caused by heterozygous mutation. This provides the first direct evidence that Nipbl haploinsufficiency affects cohesin-mediated chromatin interactions and gene expression. Our results reveal that dynamic Nipbl/cohesin binding is critical for developmental chromatin organization and the gene activation function of the LCR in mammalian cells.     

大鼠PTSD后蓝斑核 β-catenin的表达下降伴随细胞凋亡

目的 探讨创伤后应激障碍( PTSD) 大鼠蓝斑神经元β-catenin(β-连环蛋白)的表达变化.方法 采用国际认定的SPS方法刺激建立大鼠PTSD模型,取成年健康雄性Wistar 大鼠100 只,随机分为连续单一刺激( single prolonged stress,SPS) 模型1 d、4 d、7 d、14 d 组和对照组,应用免疫组化、免疫印迹方法检测PTSD 大鼠蓝斑神经元β-catenin的表达变化;透射电镜观察PTSD大鼠蓝斑神经元的超微结构变化.结果 经SPS 刺激后大鼠蓝斑神经元细胞内β-catenin于1d开始逐渐减少,14d表达最少;蓝斑神经元出现细胞凋亡改变.结论 蓝斑神经元细胞凋亡可能是导致PTSD 患者蓝斑功能失调的重要原因之一.     

Locus-specific primers for LMW glutenin genes on each of the group 1 chromosomes of hexaploid wheat

To reveal the chromosomal location of three known low-molecular-weight (LMW) glutenin genes in wheat, we designed and used three sets of sequence-specific primers in polymerase chain reactions (PCR) on Chinese Spring and its derived group 1 aneuploid nullisomic-tetrasomic stocks. Two sets proved to be chromosome specific and amplified sequences from the Glu-A3 and Glu-D3 loci, respectively. The third set was apparently composed of conserved sequences as it produced PCR products in each of the aneuploids. Two of these products were cloned, and their sequences differed from the known LMW glutenin genes at several positions. Again, primer sets specific for these sequences were designed. One set was directed to the Glu-A3 locus, the second set resulted in two PCR products differing in length, one of which was located on chromosome 1B and the other on 1D. Primer sets constructed for the latter two sequences were specific for the Glu-B3 and Glu-D3 loci, respectively. Hence, primer sets specific for each of the three homoeologous chromosomes of the group 1 (1A, 1B, 1D) are available. In addition, these locus-specific primers were assayed for their ability to distinguish among wheat cultivars. PCR products amplified with one of the Glu-A3-specific primer sets showed length polymorphisms in various wheat varieties. Varieties carrying the 1RS.1BL translocated chromosomes could be recognized by the absence of a PCR product when the Glu-B3 primer set was used. These results suggest that PCR with locus-specific primers can be useful in the molecular genetic analysis of hexaploid wheat.     

An approach to the edge effect in proof of the validity ofDice's assessment lines in small-mammal censusing

A second fieldwork for the sake of solving the edge-effect subject was carried out in almost the same ways and plans in summer of 1971 in succession to that of 1970. It was found out that the population density was reduced to two-thirds, but the data were sufficient to form the subsequent conclusions:

1. The initial population estimated by the removal census method turned out to be well compatible with the numbers of survivals and emigrants of marked voles calculated byJolly 's method.
2. The natural, entire home ranges of both sexes reached by determining observed range length and width with 24 voles, selected on rigid conditions, agreed with those of the range-conservative type in 1970 in both acreage and elliptic shape.
3. In the majority of the select specimens, considered to reveal the natural ranges, the random distribution in number of captures per station within range was proved by means of I_σ so far as such capture density as treated here is concerned. On the ground of the empirical evidence, the above range size approached by the routine observational method could be made surprisingly accordant with the range size in terms of r-values calculated byWierzbowska 's method.
4. From these proofs, the validity ofDice 's assessment lines makes evident, and besides, it could be further substantiated by use ofMarten 's notion of mouse-equivalents through the mediation ofWierzbowska 's method.
5. Consequently, I have largely come to the conclusion thatDice 's assessment lines stand on justifiable basis from theoretical and empirical angles.

     

Reduction of Noradrenaline in Cerebellum of Patients with Olivopontocerebellar Atrophy

Noradrenaline (NA) was measured in postmortem cerebellar cortex of 15 patients with dominantly inherited olivopontocerebellar atrophy (OPCA). The mean cerebellar cortical NA level was significantly reduced (by 40%) in OPCA as compared with control values. The NA deficit most likely reflects a degeneration of the locus caeruleus noradrenergic system that is known to occur in some patients with OPCA. The relationship between the altered cerebellar NA levels and the clinical symptomatology of OPCA remains to be determined.     

大鼠蓝斑核对迷走-迷走抑胃反射的加强作用

本文研究了蓝斑核对迷走-迷走抑胃反射的影响。实验结果表明,单独刺激迷走神经中枢端抑制胃电和胃运动,胃电慢波的振幅和胃内压分别下降到对照值的60.9％和45.7％,与对照值相比有明显的统计学意义(P<0.05)。刺激迷走神经中枢端的同时,以弱刺激刺激蓝斑核时,胃电慢渡的振幅和胃内压分别下降到对照值的42.1％和34.1％,与单独刺激迷走神经的效果相比较有非常显著的差异(P<0.01)。本文结果提示:蓝斑核的兴奋加强迷走-迷走抑胃反射。     

p53 checkpoint ablation exacerbates the phenotype of Hinfp dependent histone H4 deficiency

Histone Nuclear Factor P (HINFP) is essential for expression of histone H4 genes. Ablation of Hinfp and consequential depletion of histones alter nucleosome spacing and cause stalled replication and DNA damage that ultimately result in genomic instability. Faithful replication and packaging of newly replicated DNA are required for normal cell cycle control and proliferation. The tumor suppressor protein p53, the guardian of the genome, controls multiple cell cycle checkpoints and its loss leads to cellular transformation. Here we addressed whether the absence of p53 impacts the outcomes/consequences of Hinfp-mediated histone H4 deficiency. We examined mouse embryonic fibroblasts lacking both Hinfp and p53. Our data revealed that the reduced histone H4 expression caused by depletion of Hinfp persists when p53 is also inactivated. Loss of p53 enhanced the abnormalities in nuclear shape and size (i.e. multi-lobed irregularly shaped nuclei) caused by Hinfp depletion and also altered the sub-nuclear organization of Histone Locus Bodies (HLBs). In addition to the polyploid phenotype resulting from deletion of either p53 or Hinfp, inactivation of both p53 and Hinfp increased mitotic defects and generated chromosomal fragility and susceptibility to DNA damage. Thus, our study conclusively establishes that simultaneous loss of both Hinfp and the p53 checkpoint is detrimental to normal cell growth and may predispose to cellular transformation.     

刺激大鼠视上核后电针“足三里”对蓝斑灌流液中去甲肾上腺素含量的影响

运用行为测痛结合蓝斑（ＬＣ）灌流液去甲肾上腺素（ＮＥ）的高压液相（ＨＰＬＣ）测定；观察 大鼠痛阈（ＰＴ）与ＬＣ灌流液中去甲肾上腺素含量变化间的相互关系，结果表明：（ｌ）视上核 （ＳＯＮ）内注射 １０μｍＬ－谷氨酸（Ｌ－ｇｌｕｔａｍｉｃａｃｉｄ， Ｌ－Ｇｌｕ）后 ３０分钟，大鼠ＰＴ较注射前增加１３３． ２± ２１．４％，此时ＬＣ 灌流液中ＮＥ含量从注射前的４３７．３±２０．４ｎｇ／ｍｌ降到２２９．２±１１．９ｎｇ／ｍｌ，注射 后６０分钟ＰＴ仍比注射前高８３．９±１４．７％，而灌流液中ＮＥ的含量为３２８．６±２８．０ｎｇ／ｍｌ，与人工 脑脊液（ＡＣＳＦ）对照组相比有非常明显的差别（Ｐ＜０．０５～０．００１）。（２） ＳＯＮ注射Ｌ－Ｇｌｕ后，电 针足三里３０分钟（Ｌ－ＧＩＵ＋ＥＡ组）增加到注射前的１８８．２±２３．９％，同ＡＣＳＦ电针组（ＡＣＳＦ＋ ＥＡ）的 ９４．９±７．１％相比有明显差异（Ｐ＜０．０１）。此时ＬＣ灌流液中ＮＥ的含量虽较注射前都明显 降低、分别为１３７．６±７．５ｎｇ／ｍｌ和 １５１，１±１１．５ｎｇ／ｍｌ，但两者相比无明显差异。停针后３０分钟Ｌ－ Ｇｌｕ＋ＥＡ组的ＰＴ仍比注射前高１３３．８±２７．９％，明显高于     

Construction of an AFLP genetic map with nearly complete genome coverage in Pinus taeda

  De novo construction of complete genetic linkage maps requires large mapping populations, large numbers of genetic markers, and efficient algorithms for ordering markers and evaluating order confidence. We constructed a complete genetic map of an individual loblolly pine (Pinus taeda L.) using amplified fragment length polymorphism (AFLP) markers segregating in haploid megagametophytes and PGRI mapping software. We generated 521 polymorphic fragments from 21 AFLP primer pairs. A total of 508 fragments mapped to 12 linkage groups, which is equal to the Pinus haploid chromosome number. Bootstrap locus order matrices and recombination matrices generated by PGRI were used to select 184 framework markers that could be ordered confidently. Order support was also evaluated using log likelihood criteria in MAPMAKER. Optimal marker orders from PGRI and MAPMAKER were identical, but the implied reliability of orders differed greatly. The framework map provides nearly complete coverage of the genome, estimated at approximately 1700 cM in length using a modified estimator. This map should provide a useful framework for merging existing loblolly pine maps and adding multiallelic markers as they become available. Map coverage with dominant markers in both linkage phases will make the map useful for subsequent quantitative trait locus mapping in families derived by self-pollination. Received: 7 August 1998 / Accepted: 27 October 1998