COMPARATIVE HYDROLYSIS OF GELATIN BY PEPSIN,TRYPSIN, ACID,AND ALKALI

A comparison has been made of the relative velocity of hydrolysis of the various peptid linkings of the gelatin molecule when hydrolyzed by acid, alkali, pepsin or trypsin. It has been found that: 1. Those linkages which are most rapidly split by pepsin or trypsin are among the more resistant to acid hydrolysis. 2. Those linkages which are hydrolyzed by pepsin are also hydrolyzed by trypsin. 3. Trypsin hydrolyzes linkages which are not attacked by pepsin. 4. Of the linkages which are hydrolyzed by both enzymes, those which are most rapidly hydrolyzed by pepsin are only slowly attacked by trypsin. 5. Those linkages which are attacked by trypsin or pepsin are among the ones first (most rapidly) hydrolyzed by alkali. In general it may be said that the course of the early stages of hydrolysis of gelatin is similar with alkali, trypsin, or pepsin and quite different with acid.     

应用比色法测定蚊虫摄血量

估测蚊虫的摄血量对某些蚊媒病的流行病学和有关蚊虫生理学研究均有一定参考价值。前人曾应用称重法和放射性同位素示踪技术来测定蚊虫摄血量(Clements,1963)。我们曾采用酸化血色素稀释比色法(简称比色法)对3种较常见的实验室蚊虫——白纹伊蚊、中华按蚊和斯氏按蚊的摄血量进行了初步测定,并与称重法进行了比较,现简介如下。     

特效黄杆菌对蒽菲芘的降解性能研究*

采用定时、定量、逐步提高驯化所用碳源物浓度的方法 ,以萘为唯一碳源驯化长期被焦化废水污染的泥土浸出液 ,7周后 ,平板划线分离出两株黄杆菌FCN1及FCN2。并对这两株菌降解多环芳烃的特性及无机离子对反应的刺激作用进行了研究。结果表明 ,FCN1及FCN2能降解转化蒽、菲、芘。加入FCN1 ,反应 1 0h后 ,蒽、菲、芘去除率分别为84%、69%、 80 % ,而加入FCN2 ,各物质的去除率分别为 76%、 40 %、 71 %。反应进行1 0 6h,FCN1对蒽、菲、芘所产生的总有机碳 (TOC)的     

UPTAKE OF GUANINE BY THE DIATOM,PHAEODACTYLUM TRICORNUTUM1

Nitrate-cultured cells of Phaeodactylum tricornutum Bohlin lack the ability to take up guanine but can do so after a period of nitrogen deprivation, i.e. photosynthesis in nitrogen-free medium. Maximum rate of uptake occurred after 24 h of nitrogen deprivation. The development of ability to take up guanine required CO₂ fixation and was prevented by cycloheximide, ammonium or nitrate. The guanine taken up accummulated in the cells almost entirely as a compound which is probably methylated hypoxanthine. Guanine uptake was dependent upon metabolism and exhibited Michaelis-Menten like kinetics with a half-saturation value of 0.48 ± 0.05 μM guanine and a maximum uptake rate for guanine of ca. 200 nmol · 10^?8 cells · h^?1. Rate of uptake increased hyperbolically with Na⁺ concentration, with 8.25 mM Na⁺ supporting half-maximal rate, and it was inhibited by K⁺ ions.     

CHLOROPHYLL-SENSITIZED REDUCTION OF PLASTOQUINONE BY ASCORBIC ACID AND QUENCHING OF CHLOROPHYLL-FLUORESCENCE BY PLASTOQUINONE

1. Photochemical reduction of plastoquinone by ascorbic acid inethanol was sensitized with some derivatives of chlorophyll.The order of effectiveness was as follows: allomerized chlorophylla > chlorophyllin a > chlorophyll a > chlorophyll b> pheophytin a.
2. Quenching of the fluorescence of chlorophylla by plastoquinonewas observed. The quenching constant calculatedwas 71 litreper mole.

¹Contribution No. 159 from the Department of Biology, Facultyof Science, Kyushu University. Supported in part by a grant-in-aidfor Fundamental Scientific Research from the Ministry of Education. ²Present address: Biological Laboratory, General Education Department,Kyushu University, Ropponmatsu, Fukuoka. ³Present address: Biological Institute, Daiichi College of PharmaceuticalSciences, Tamagawa-machi, Takamiya, Fukuoka.     

牧效黄杆菌对蒽菲芘的降解性能研究

采用定时、定量、逐步提高驯化所用碳源物浓度的方法,以萘为唯一碳源驯化长期被焦化废水污染的泥土浸出液,7周后,平板划线分离出两株黄杆菌FCN1及FCN2。并对这两株菌降解多环芳烃的特性及无机离子对反应的刺激作用进行了研究。结果表明,FCN1及FCN2能降解转化蒽、菲、芘。加入FCN1,反应10h后,蒽、菲、芘去除率分别为84％、69％、80％,而加入FCN2,各物质的去除率分别为76％、40％、71％。反应进行106h,FCN1对蒽、菲、芘所产生的总有机碳（TOC）的去除率分别为70％、54％、69％,而FCN2对相应物的TOC去除率分别为63％、50％、46％。Fe^3 、Mg^2 的加入对FCN1降解多环芳烃有促进作用。