THE EFFECT OF NaCl ON THE PHAGE-BACTERIUM REACTION

1. The presence of 0.25 M NaCl during the reaction between a staphylococcus phage and susceptible organisms results in a five to tenfold increase in the amount of phage produced. 2. Analysis of the reaction indicates that normal kinetic relationships exist until just before lysis occurs. At this time the organisms enter the stationary phase, lysis is delayed approximately 0.7 hour as compared with control mixtures and phage continues to be produced at the usual rapid rate. 3. Apparently there are conditions under which phage can be produced in the absence of bacterial growth although previous work has uniformly emphasized growth of the bacterial substrate as the prime conditioning factor for formation of phage.     

THE ACTION OF SODIUM DODECYL SULFATE ON THE CHLOROPHYLL-PROTEIN COMPOUND OF THE SPINACH LEAF

1. Sodium dodecyl sulfate (SDS) attacks the chlorophyll-protein compound modifying its protein properties and absorption spectrum. 2. In the presence of SDS, chlorophyll is quantitatively converted to phaeophytin; i.e., magnesium is removed from the molecule. This reaction, measured spectrophotometrically, proceeds at a rate directly proportional to the hydrogen ion concentration. At constant pH, the rate is proportional to the SDS concentration until a maximum rate is achieved. 3. The chlorophyll or phaeophytin (depending on the pH) remains attached to the protein, since the prosthetic group cannot be separated by ultrafiltration, dialysis, or fractional precipitation. 4. This suggests that the magnesium plays no part in binding chlorophyll to the split protein fragments, but may be concerned in binding the larger units, since the metal becomes extremely labile when the protein is split.     

光敏反应对过氧化氢酶的影响

光氧化反应中,纯过氧化氢酶活性受光敏化剂血卟啉Ⅳ和核黄素的抑制。随光敏化剂浓度增高及照光时间延长,抑制程度加大。酶与光敏化剂反应后吸收光谱位移,峰形改变。紫外差示吸收光谱出现229nm负峰(血卟啉)和236—240nm峰(核黄素)。结果表明酶活的抑制与其蛋白构象的变化相关。     

亚硫酸氢钠对大蒜幼苗生长及细胞分裂的作用

研究SO2体内衍生物-亚硫酸钠与亚硫酸氢钠（分子比为3：1）混合液对大蒜幼苗生长和细胞分裂的效应。结果表明：低浓度（0.2mmol/L）的混合液促进幼苗生长,短时间（24h）作用时根尖细胞有丝分裂指数（MI）提高;高浓度（1.5与2.0mmol/L）处理抑制大蒜幼苗生长,细胞周期涎滞,大蒜根尖MI下降,并诱发细胞分裂异常,且呈明显的时间效应与剂量效应关系。     

THE EFFECT OF CYSTINE AND GLYCOCOLL ON THE OXIDATION OF SODIUM LACTATE BY HYDROGEN PEROXIDE

The rate of production of CO₂ from sodium lactate when treated with H₂O₂ may be increased by the addition of a compound containing a sulfhydryl group, i.e. cystine. A small part of this increase in rate of CO₂ is due to the action of the amino group as shown by the action of glycocoll. The results tend to show that the mode of action of H₂O₂ is one of dehydrogenation and that the action of the cystine is comparable to the Atmungskörper of Meyerhof.     

烷基聚氧乙烯醚硫酸钠对肌酸激酶的变性及复性

系统的研究了十二烷基聚氧乙烯醚硫酸钠Ｃ１２Ｈ２５（ＯＣ２Ｈ４）ｎＳＯ４Ｎａ（ｎ＝０,１,３,５,７;记为Ｃ１２ＥｎＳ）对肌酸激酶的活力和构象的影响。结果表明：随着氧乙烯基个数（ｎ）的增加,Ｃ１２ＥｎＳ对Ｃ．Ｋ．的活力破坏逐步减小;Ｃ１２ＥｎＳ引起Ｃ．Ｋ活力的丧失明显早于可测构象的变化。ＣＫ经Ｃ１２ＥｎＳ变性后,稀释时即可完全复性。Ｃ１２Ｅ７Ｓ不仅对Ｃ．Ｋ的变性能力强（１０ｍＭ就使Ｃ．Ｋ完全失活）;而且在１０－９５℃的温度范围内,能阻止Ｃ．Ｋ聚集沉淀。Ｃ１２ＥｎＳ是Ｃ．Ｋ的高效可逆变性剂。     

氯霉素对大鼠睡眠和主动回避反应的影响

本文报导了氯霉素在大鼠生后7天内和鼠龄60天时给药对其成熟后的睡眠、主动回避反应以及电休克阈的影响。在新生期给药组,快眼动睡眠量显著减少,但主动回避反应成绩没有明显变化.在鼠龄60天给药组,动物的快眼动睡眠量和主动回避反应成绩均明显降低,电休克阈也降低。文中讨论了氯霉素对快眼动睡眠和脑发育的影响以及发育期快眼动睡眠与脑发育的关系。     

癌血清对小鼠SCM反应的特异抑制作用

癌血清对小鼠脾淋巴细胞SCM反应的抑制作用可用于区别健康者、非癌患者和癌症。前者RR_(SCM)<80—85%,后者>90%。癌血清的这种抑制作用呈浓度和时间相关,无种属特异性,而仅与肿瘤的恶性与否相关。在癌症早期可出现这一抑制作用,并随癌肿的移去而消失。与Cercek经典方法或同位素参入等方法相比,本方法在易判性、可靠性、简便性方面都具优点、有理论研究和实用价值。     

THE EFFECT OF SODIUM CHLORIDE ON CARBONIC ANHYDRASE ACTIVITY IN MARINE MICROALGAE1

The effects of NaCl on the internal and external carbonic anhydrase (CA) activity of several marine microalgae were studied. Unlike freshwater microalgae in which CA activity is generally inhibited by NaCl, marine microalgae exhibited considerable species-dependent variation when exposed to NaCl. CA activity in Phaeodactylum tricornutum, a diatom, was inhibited, whereas it was activated in the coccolithophorid Pleurochrysis carterae. CA activity in the chlorophyte Dunaliella primolecta was not significantly affected by NaCl. In Dunaliella salina and Dunaliella parva, NaCl inhibited external CA without affecting the internal activity, whereas in Chlorella vulgaris C-133 and Dunaliella peircei only the internal CA was inhibited. Internal CA of Dunaliella tertiolecta was not affected by NaCl, but the external enzyme was significantly enhanced. Salt substitution experiments revealed that chloride (Cl^-) is the ion affecting CA activity; the effect of Cl^- can be replaced by bromide ion. Cl^- affects external CA activity while also affecting the apparent affinity for inorganic carbon during photosynthesis. Microalgae whose internal CA activity was enhanced by Cl^- showed higher intracellular Cl^- concentrations than those species that were inhibited.     

丁酸钠对人胃腺癌SGC-7901细胞的生物学效应

应用兔抗纤维粘(连)蛋白(FN)抗体和兔抗3t,5,环腺苷酸(cAMP)特异性抗体,并用羊抗兔IgG荧光抗体,在荧光显微镜下观察丁酸钠对人胃腺癌SGC一7901细胞系的纤维粘(连)蛋白(FN)和cAMP水平的变化。实验结果表明丁酸钠有增强SGC一7901细胞内纤维粘(连)蛋白(FN)和c.~MP水平的作用;应用电镜细胞化学和扫描电镜的技术方法,观察到人胃腺癌SGC一7901细胞在丁酸钠作用下膜表而(Na 一K )一ATP酶活性明显下降;微绒毛明显减退,膜表面较光滑。这可能说明丁酸钠通过抑制(Na~一K )一ATP酶活性,提高了细咆内cAMP水平,调控细胞的增殖和分化。     

植酸钠对黑曲霉柠檬酸发酵产酸的促进效应

研究了植酸钠对黑曲霉柠檬酸发酵产酸的促进效应。在葡萄糖全合成培养基中添加１％的植酸钠,可使产酸比对照提高２．４倍;在薯粉、玉米粉等天然培养基中添加１％植酸钠,柠檬酸产量分别提高１．７倍和１．３倍。酶活性测定分析表明,植酸钠对柠檬酸代谢途径中的几种关键酶的活性有影响。     

A STUDY OF THE EFFECT OF MILDEW INFECTION ON THE REACTION OF WHEAT VARIETIES TO BROWN RUST

The effect of the presence of Erysiphe graminis tritici on the reactions of each of five wheats, Malakoff, Democrat, Mediterranean, Hussar and Webster, to Puccinia triticina was studied. Under normal environmental conditions, mildew increased the susceptibility to rust of Malakoff and Democrat, though not, except in isolated instances, that of Mediterranean or Hussar. High light intensities enhanced the effect of mildew on the reaction of Democrat to P. triticina. The susceptibility of Webster to rust was unaffected or decreased by the presence of mildew.
In all varieties there was a decided tendency for rust and mildew to develop on different parts of the leaf, and when a leaf was heavily mildewed the development of P. triticina was sometimes almost entirely inhibited. The reason for this is obscure, since spores of P. triticina and E. g. tritici germinate well in each others presence, and cytological studies revealed several cases of the presence of both mildew and rust haustoria in a single living host cell. Anatomical investigations also showed that the effect of mildew on rust infection was confined to rust pustules within 1 mm. of mildew colonies.
The results obtained are in accordance with Gassner's theory that susceptibility to rust is due to the presence of certain specific proteins in the host leaf.