D10S20, a previously unmapped RFLP (OS-3), is located on 10q near D10S4

The locus recognized by the probe OS-3 is assigned to chromosome 10 both by Southern blot analysis of a panel of somatic cell hybrid DNAs and by genetic linkage to markers already assigned to chromosome 10. In Caucasians this probe recognizes a three-allele TaqI RFLP as well as two-allele BanII and RsaI RFLPs which are both in strong linkage disequilibrium with each other and with the TaqI RFLP. The D10S20 locus defined by this probe maps 5.5 cM distal to D10S4 on the long arm of chromosome 10. Because this human clone hybridizes with mouse genomic DNA, it will be useful in comparative mapping studies.     

Genotyping and sequence analysis of apolipoprotein E isoforms

Apolipoprotein E (apoE), a polymorphic plasma protein, is essential for catabolism of lipoproteins by receptor-mediated endocytosis. One of the apoE isoforms (E2) differs in its binding affinity to specific receptors and contributes to variations in lipoprotein metabolism. Diagnosis of apoE isoforms is done by isoelectric focusing, but it is hindered by various degrees of post-translational sialylation of the apoE protein. Electrophoretically silent structural variations may also escape detection by this technique. We describe a method for genotyping apoE based on hybridization of allele-specific oligonucleotides with enzymatically amplified genomic DNA, which permits unambiguous diagnosis of six common apoE phenotypes within 24 h. Among 100 E2 alleles present in 81 unrelated individuals genotyped by this technique, we found two rare structural mutants of apoE in addition to the common E2 form, E2(158Arg----Cys). Automated sequencing of amplified DNA identified the rare mutants as E2(136Arg----Ser) and E2(145Arg----Cys). The genotypic method may complement or even replace isoelectric focusing for routine determination of apoE phenotypes and for identification of rare structural variants.     

Genetic linkage between lipoprotein(a) phenotype and a DNA polymorphism in the plasminogen gene

Coronary heart disease risk correlates directly with plasma concentrations of lipoprotein(a) (Lp(a)), a low-density lipoprotein-like particle distinguished by the presence of the glycoprotein apolipoprotein(a) (apo(a)), which is bound to apolipoprotein B-100 (apoB-100) by disulfide bridges. Size isoforms of apo(a) are inherited as Mendelian codominant traits and are associated with variations in the plasma concentration of lipoprotein(a). Plasminogen and apo(a) show striking protein sequence homology, and their genes both map to chromosome 6q26-27. In a large family with early coronary heart disease and high plasma concentrations of Lp(a), we found tight linkage between apo(a) size isoforms and a DNA polymorphism in the plasminogen gene; plasma concentrations of Lp(a) also appeared to be related to genetic variation at the apo(a) locus. We found free recombination between the same phenotype and alleles of the apoB DNA polymorphism. This suggests that apo(a) size isoforms and plasma lipoprotein(a) concentrations are each determined by genetic variation at the apo(a) locus.     

中国兔猴的单一物种及其两性差别

观察到以前描述的中国兔猴不同种的特征在禄丰的全部中国兔猴标本中交叉地存在、并通过连续的中间表现型而衔接,本文建议石灰坝中国兔猴是厚齿中国兔候的同种异名,因而前一名称应予取消。以犬齿和下第四前臼齿为材料研究了中国兔猴的两性差别。本文使用双变量分布确定两性重叠分布的测量性状的性别差异取得较好的效果。     

小鼠腹水型肝癌H22a细胞浆内磷蛋白磷酸酶活力调节的研究

小鼠腹水型肝癌细胞胞浆内磷蛋白磷酸酶对磷酸化的组蛋白、酪蛋白、鱼精蛋白具有脱磷酸化活力,而对小分子底物P-Ser、P-Thr、P-Tyr、PNPP等无活力。二价金属离子Mn~(2+)、Co~(2+)、Mg~(2+)对酶有明显激活作用,而Zn~(2+)、F~-、Pi对酶有明显抑制作用。代谢中间物G-6-P、G-1-P、F-6-P、F-1.6-2P、ATP、ADP、GTP对酶有抑制作用,而磷酸化氨基酸和环核苷酸对酶活影响很小。还试验了碱性蛋白质和酸性蛋白质对酶活力的影响,肝素和组蛋白均对酶活力有抑制作用,当两者混和后,其抑制作用会相互抵消。     

St14/TaqⅠRFLPs在甲型血友病基因探测与产前基因诊断中的应用

<正> 甲型血友病是最常见的遗传性凝血疾病,是由于凝血因子Ⅷ(FVⅢ)基因缺陷所致。目前对此病尚无满意的治疗方法。利用DNA分析技术进行甲型血友病基因检测与产前基因诊断对开展优生优育有重要的实际应用价值。由于FⅧ基因组织结构庞大,分子病理改变复杂,目前多采用DNA限制酶片段长度多态性(RFLPs)为遗传标志对有缺陷的FⅧ基因进行连锁分析。St 14(DXS52)是人X染色体长臂远端的一段基因外DNA序列,与FⅧ基因紧密连锁。国外已将St14/Taq Ⅰ RFLPs用于甲型血友病基因携带者的检测,但尚未见到用于产前基因诊断的报道。我们利用引进的St14片段为探针,采用简化的低脂奶粉杂交体系和DNA凝胶原     

猪肺炎支原体膜上ATP酶生化性质的研究

猪肺炎支原体膜上ATP酶为Mg~(2+)激活,乌巴因不抑制。DCCD和寡霉素对该酶也无抑制作用,只有NBD与Quercetin才有一定的抑制效果。用梯度凝胶电泳可获均一的具有活性的酶蛋白带。     

MAP kinase activator from insulin-stimulated skeletal muscle is a protein threonine/tyrosine kinase.

A 'MAP kinase activator' was purified several thousand-fold from insulin-stimulated rabbit skeletal muscle, which resembled the 'activator' from nerve growth factor-stimulated PC12 cells in that it could be inactivated by incubation with protein phosphatase 2A, but not by protein tyrosine phosphatases and its apparent molecular mass was 45-50 kDa. In the presence of MgATP, 'MAP kinase activator' converted the normal 'wild-type' 42 kDa MAP kinase from an inactive dephosphorylated form to the fully active diphosphorylated species. Phosphorylation occurred on the same threonine and tyrosine residues which are phosphorylated in vivo in response to growth factors or phorbol esters. A mutant MAP kinase produced by changing a lysine at the active centre to arginine was phosphorylated in an identical manner by the 'MAP kinase activator', but no activity was generated. The results demonstrate that 'MAP kinase activator' is a protein kinase (MAP kinase kinase) and not a protein that stimulates the autophosphorylation of MAP kinase. MAP kinase kinase is the first established example of a protein kinase that can phosphorylate an exogenous protein on threonine as well as tyrosine residues.     

Heart sarcolemmal Ca2+ transport in endotoxin shock: I. Impairment of ATP-dependent Ca2+ transport

Effects of endotoxin administration on the ATP-dependent Ca²⁺ transport in canine cardiac sarcolemma were investigated. The results show that the sidedness of the sarcolemmal vesicles was not affected but the ATP-dependent Ca²⁺ transport in cardiac sarcolemma was decreased by 22 to 46% (p < 0.05) at 4 h following endotoxin administration. The kinetic analysis indicates that the V_max for ATP and for Ca²⁺ were decreased by 50% (p < 0.01) and 32% (p < 0.01), respectively, while the Km values for ATP and Ca²⁺ were not significantly affected after endotoxin administration. Magnesium (1–5 mM) stimulated while vanadate (0.25–3.0 M) inhibited the ATP-dependent Ca²⁺ transport, but the Mg²⁺-stimulated and the vanadate-inhibitable activities remained significantly lower in the endotoxin-treated animals. These data demonstrate that endotoxin administration impairs the ATP-dependent Ca²⁺ transport in canine cardiac sarcolemma and that the impairment is associated with a mechanism not affecting the affinity towards ATP and Ca²⁺. Additional experiments show that the Ca²⁺ sensitivity of the Ca²⁺-ATPase activity was indifferent between the control and endotoxic groups suggesting that endotoxic injury impairs Ca²⁺ pumping without affecting Ca²⁺-ATPase activity. Since sarcolemmal ATP-dependent Ca²⁺ transport plays an important role in the regulation of cytosolic Ca²⁺ homeostasis, an impairment in the sarcolemmal ATP-dependent Ca²⁺ transport induced by endotoxin administration may have a pathophysiological significance in contributing to the development of myocardial dysfunction in endotoxin shock.