足籽骨的放射片研究

本文对山东枣庄市916人足放射片进行了足籽骨的观察与测量。发现每足有1-7个籽骨,其中二个者占77.8％,三个者占16.9％;籽骨位于跖骨头下方者占94.5％,位于趾间关节下方者占5.5％;各跖骨头籽骨出现率:Ⅰ占99.9％、Ⅱ占 2.2％、Ⅲ占0.3％、Ⅳ占0.5％、Ⅴ占6.4％;(足母)趾趾间关节籽骨占12.6％;二分及三分籽骨出现率占3.9％,明显低于欧美人。此外,本文认为籽骨是在先天籽骨原基基础上,加以后天运动的影响而形成。     

中国某些野生和栽培茶的核型研究

研究了茶的4个变种和广东野生毛叶茶等共12个材料的核型。所有材料的染色体数目均是2n=30,为二倍体。所有中国大叶变种(越南大叶除外)(Cametlia sinensis var. macrophylla)和阿萨姆大叶变种(C. sinensis var. assamica)均具比较对称或原始的“2A”核型;中国小叶变种(C.sinensis var.bohea)(“铁观音”品种除外),掸部变种(C.sinensis var. shan form)和广东野生毛叶茶(C. ptilophylla)均具较不对称或较进化的“2B”核型。根据核型特征,植物习性和地理分布,作者认为中国四川和云南可能是茶的起源中心,向东或北迁移,演变为中国小叶变种;向南移则演变为阿萨姆变种和掸部变种。     

琼脂糖平板制备聚焦电泳法进一步提纯胸腺素组分五

用琼脂糖平板等电聚焦电泳法,由胸腺素组分五中分离出三种在聚焦电泳谱上是单一谱线的多肽成份——CP1、CP2和CP3,等电点分别为4.3、4.9和5.6。测定了这些多肽对脐带血中淋巴细胞形成羊红细胞玫瑰花的影响。与对照相比,CP1(2微克/0.6毫升),和CP3(0.2-2微克/毫升)分别在统计学上呈显著和非常显著差异。在相同测定条件下,这三种多肽成份的活性均高于化学合成的胸腺多肽——胸腺素α_1。     

大鼠非致瘤四倍体细胞系的建立及细胞遗传学和酶学特征

从大鼠自然诱发的肉瘤细胞中,我们建立了一个四倍体细胞系(4n=84),命名为RC(ratcell)。它具有典型的成纤维细胞外形,能在玻璃表面贴壁生长,但不能生长在琼脂半固体培养基中。该细胞在含15％小牛血清的RPMI 1640培养基中生长良好,至今已连续繁殖112世代,细胞群体倍增时间约为15小时。染色体G-带分析表明,RC为整四倍体细胞,它的1条X染色体在第32至34区为均染区。RC细胞核仁组织者(NORs)活性显然比大鼠二倍体细胞NORs活性的加倍还高(P<0.001)。这个具有非常高NORs活性的RC细胞系对于研究细胞18S+28S rRNA基因转录活性的调控、基因表达与基因剂量关系有一定的意义。RC细胞还有异常高的磷酸酯酶活性,而且它的同工酶谱也与大鼠肌肉细胞明显不同。体内接种实验和扫描电镜的观察表明,RC是非致瘤细胞。RC细胞各号染色体的C-带图样与大鼠二倍体细胞无明显的差异。     

Influence of both coculture and BrdU on NOR activity of mouse,rat and human cells

Summary The coculture of mouse PG19 cells with human MGC cells can significantly suppress nucleolar organizer region (NORs) activity of both PG19 and MGC cells. 5-bormodeoxyuridine (BrdU) can also significantly suppress the NOR activity of rat RC cells, human MGC and Hela cells, and mouse PG19 cells: i.e. the average number of Ag-NORs and the number of chromosomes bearing Ag-NORs per cell decrease significantly. The degree of the suppression increases with increase in both BrdU concentration in the culture medium and BrdU treatment time. The suppressed NOR activity of the PG19 cells can gradually be restored when the BrdU-treated cells are transferred into BrdU-free medium for 50 h. In PG19 cells deoxycytidine (dC) can reverse the suppression of NOR activity caused by BrdU. Coculture plus BrdU treatment suppress the NOR activity of PG19 cells more severely than BrdU treatment alone. In coculture medium containing 30 g BrdU/ml, dC can also reverse the suppression of the NOR activity of PG19 cells but not that of the MGC cells. The degree of the reversion in the coculture plus BrdU treatment is significantly lower than that found with BrdU-treatment alone.     

The effect of temperature on the acetylcholinesterase activity of muscle microsomes

Membrane vesicles which constitute the sarcotubular system were separated and the fraction enriched in T-tubules purified by a calcium loading procedure. The preparations of unfractioned microsomes and T-tubules have been analyzed for their relative content of enzyme markers and acetylcholinesterase. The amount of this enzyme in the T-tubule fraction was higher than in mixed microsomes but less than two-fold the value of vesicles derived from sarcoplasmic reticulum. Arrhenius plots of membrane-bound and soluble acetylcholinesterase from either mixed microsomes or fractions enriched in T-tubules show an anomalous behaviour as two break points were obtained. The first discontinuity was found at about 17 degrees C for membrane-bound, and 12-14 degrees C for soluble acetylcholinesterase. The second one being at about 25 degrees C for both particulate and detergent-solubilized enzyme. The changes in activity with temperature suggest that lipid-protein, detergent-protein and protein-protein interactions might be involved in the stabilization of the enzyme both in the natural membrane and in the soluble state.     

Study of the hydrolysis and ionization constants of Schiff base from pyridoxal 5''-phosphate and n-hexylamine in partially aqueous solvents. An application to phosphorylase b.

Formation and hydrolysis rate constants as well as equilibrium constants of the Schiff base derived from pyridoxal 5'-phosphate and n-hexylamine were determined between pH 3.5 and 7.5 in ethanol/water mixtures (3:17, v/v, and 49:1, v/v). The results indicate that solvent polarity scarcely alters the values of these constants but that they are dependent on the pH. Spectrophotometric titration of this Schiff base was also carried out. We found that a pKa value of 6.1, attributed in high-polarity media to protonation of the pyridine nitrogen atom, is independent of solvent polarity, whereas the pKa of the monoprotonated form of the imine falls from 12.5 in ethanol/water (3:17) to 11.3 in ethanol/water (49:1). Fitting of the experimental results for the hydrolysis to a theoretical model indicates the existence of a group with a pKa value of 6.1 that is crucial in the variation of kinetic constant of hydrolysis with pH. Studies of the reactivity of the coenzyme (pyridoxal 5'-phosphate) of glycogen phosphorylase b with hydroxylamine show that this reaction only occurs when the pH value of solution is below 6.5 and the hydrolysis of imine bond has started. We propose that the decrease in activity of phosphorylase b when the pH value is less than 6.2 must be caused by the cleavage of enzyme-coenzyme binding and that this may be related with protonation of the pyridine nitrogen atom of pyridoxal 5'-phosphate.