拉萨郊区藏族跖纹主线走向分析

本文用茚三酮－味精法采集跖纹,体视显微镜下追踪跖纹主线走向,分析了２５０（男女各１２５人）拉萨效区藏族健康人的跖纹样本。结果显示：Ａ线主要走向１区,其次是７区;Ｂ线亦多止于１区和７区;Ｃ线主要止于和９区;Ｄ线止于１区 频率最高;Ｅ线主要走向１３区;Ｐ三叉缺失较多。Ｐｚ＾ｄ线止共位置较高（１３区和１１区）,而Ｐ＾ｆ线止区较低（７区）。在民族和人种间进行了比较,提示藏族践纹主线走向有自己的特点,又呈现     

Differential effects of corticotropin-releasing hormone on central dopaminergic and noradrenergic neurons

Corticotropin-releasing hormone (CRH) has been shown to be a central mediator for most, if not all, stress-induced responses. Since stressful stimuli may decrease hypothalamic tuberoinfundibular and tuberohypophysial dopaminergic neuronal activities, we aimed to determine whether CRH is involved. Using central administration of various doses of ovine CRH (oCRH; 1, 3 and 10 µg/rat) into the lateral cerebroventricle of either male or female rats, the neurochemical changes in various parts of the central nervous system, including the hypothalamus, were determined by high-performance liquid chromatography at various times after the injection (30, 60, 120 and 240 min). The concentrations of 3,4-dihydroxyphenylacetic acid (DOPAC) and 3-methoxy-4-hydroxy-phenylethyleneglycol (MHPG), two major metabolites of dopamine and norepinephrine, respectively, in discrete brain regions were used as indices for catecholaminergic neuron activity. Plasma corticosterone levels increased significantly after all doses of oCRH and at all time points studied. oCRH also exerted significant stimulatory effects on noradrenergic neuron terminals in the frontal cortex, and on dopaminergic neuron terminals in the nucleus accumbens, hypothalamic paraventricular and periventricular nuclei, and intermediate pituitary lobe. Dopaminergic neuron terminals in the median eminence and the neural lobe of the pituitary, however, were not affected. There was no major difference in the responses between male and female rats. We conclude that CRH has a differential effect on central catecholaminergic neurons.     

Trace elements in hair of blackfoot disease

Blackfoot disease is a peripheral vascular disease resulting in gangrene of the lower extremities. Though extensive epidemiological study has implicated that high arsenic content in artesian well water of the endemic area, bears some important connection with the disease, the etiology of the disease is still unknown. In this study, attention is paid to multielement determination in order to find out whether the trace elements in hair of Blackfoot disease patients are different from those of the controls. Experimental results indicate that the concentrations of As and Se in hair of patients are significantly higher than those of the controls, but Ca and Zn are significantly lower than those of the controls. The possible connection of these elements with the etiology of the disease is discussed.     

Genetics of sex determination in flowering plants

Most flowering plant species are hermaphroditic, but a small number of species in most plant families are unisexual (i.e., an individ-ual will produce only male or female gametes). Because species with unisexual flowers have evolved repeatedly from hermaphroditic progenitors, the mechanisms controlling sex determination in flowering plants are extremely diverse. Sex is most strongly determined by genotype in all species but the mechanisms range from a single controlling locus to sex chromosomes bearing several linked locirequired for sex determination. Plant hormones also influence sex expression with variable effects from species to species. Here, we review the genetic control of sex determination from a number of plant species to illustrate the variety of extant mechanisms. We emphasize species that are now used as models to investigate the molecular biology of sex determination. We also present our own investigations of the structure of plant sex chromosomes of white campion (Silene latifolia - Melan-drium album). The cytogenetic basis of sex determination in white campion is similar to mammals in that it has a male-specific Y-chromosome that carries dominant male determining genes. If one copy of this chromosome is in the genome, the plant is male. Otherwise it is female. Like mammalian Y-chromosomes, the white campion Y-chromosome is rich in repetitive DNA. We isolated repetitive sequences from microdissected Y-chromosomes of white campion to study the distribution of homologous repeated sequences on the Y-chromosome and the other chromosomes. We found the Y to be especially rich in repetitive sequences that were generally dispersed over all the white campion chromosomes. Despite its repetitive character, the Y-chromosome is mainly euchromatic. This may be due to the relatively recent evolution of the white campion sex chromosomes compared to the sex chromosomes of animals. © 1994 Wiley-Liss, Inc.     

Distribution and regulation of natriuretic factor-R1C receptor subtypes in mammalian cell lines

The differential distribution of natriuretic peptide receptor subtypes and their distinct properties were assessed in mammalian cellular models which were screened for their ability to produce cGMP upon stimulation by different natriuretic peptides. The ANF-R_1A receptor subtype was distinguished by its selective activation by atrial natriuretic factor (ANF) while the ANF-R_1C was characterized by preferential stimulation by C-type natriuretic peptide (CNP). AT-t20 pituitary cells, bovine adrenal chromaffin cells, and NIH-3T3 fibroblasts mainly express the ANF-R_1C receptor subtype. Other cell lines such as PC12, RASM and GH3 express significant but varying amounts of both ANF-R_1A and ANF-R_1C subtypes. A10 and NIH cells which express high density of ANF-R₂ receptor subtype, also demonstrate a higher sensitivity to CNP over ANF suggesting that they express significant amounts of ANF-R_1C. Studies of the regulation by ATP of guanylyl cyclase activity indicate that both ANF-R_1A and ANF-R_1C subtypes are modulated in the same manner. In the presence of Mn²⁺, ATP inhibits the CNP-stimulated guanylyl cyclase activity while in the presence of Mg²⁺ adenine nucleotides potentiate the stimulation by CNP. In addition, we show that like the ANF-R_1A, the ANF-R_1C guanylyl cyclase activity can be regulated by phosphorylation since preincubation with TPA or FKL attenuates the subsequent stimulation by CNP in cultured cells. The results presented demonstrate that specific cell types express distinct natriuretic peptide receptor subtypes and also that the newly characterized ANF-R_1C subtype is regulated by ATP and serine/threonine kinases in the same way as the ANF-R_1A subtype.Abbreviation ANF atrial natriuretic factor - BNP brain natriuretic peptide - CNP C-type natriuretic peptide - ATP adenosine-5-triphosphate - IBMX 3-isobutyl-1-methylxanthine - TPA 12-O-tetradecanoyl-phorbol-13-acetate - FKL forskolin - PKC calcium-phospholipid-dependent protein kinase - PKA cAMP-dependent protein kinase - PKG cGMP-dependent protein kinase - C-ANF [Cys¹¹⁶]-ANF-(102-116)-NH₂ - CC chromaffin cells     

湖羊瘤胃微生物GH9家族葡聚糖酶基因IDSGLUC9-25的表达与功能表征

【目的】葡聚糖酶是饲用添加剂的重要成分,本研究旨在从湖羊消化道微生物中挖掘性质优良的GH9家族葡聚糖酶基因,用于研发新型饲用酶制剂。【方法】从湖羊瘤胃微生物cDNA中扩增IDSGLUC9-25基因,在大肠杆菌中进行异源表达,对重组蛋白进行诱导表达和纯化,研究重组蛋白的酶学性质和底物水解模式。【结果】IDSGLUC9-25基因编码527个氨基酸,包含一个CelD_N结构和一个GH9家族催化结构域;重组蛋白rIDSGLUC9-25分子量约为62.7 kDa,最适反应温度和pH分别为40℃和6.0,在30-50℃下活性较高,在pH 4.0-8.0范围内能够保持较高的稳定性,经pH 4.0-8.0缓冲液处理1 h后残余活性均大于90%;底物谱分析表明,rIDSGLUC9-25能催化大麦β-葡聚糖、苔藓地衣多糖、魔芋胶和木葡聚糖,比活性分别为(443.55±24.48)、(65.56±5.98)、(122.37±2.85)和(159.16±7.73) U/mg;利用薄层色谱法(thin layer chromatography, TLC)和高效液相色谱法(high performance liquid chromatography, HPLC)分析水解产物发现,rIDSGLUC9-25降解大麦葡聚糖主要生成纤维三糖(占总还原糖64.19%±1.19%)和纤维四糖(占总还原糖26.24%±0.12%),催化地衣多糖主要生成纤维三糖(占总还原糖78.46%±0.89%)。【结论】本研究报道了一种来自密螺旋体属细菌的内切β-1,4-葡聚糖酶IDSGLUC9-25 (EC 3.2.1.4),能高效催化多糖底物生成纤维三糖和纤维四糖,为研发饲用酶制剂和制备低聚寡糖建立基础。