An electron-transport system associated with the outer membrane of liver mitochondria. A biochemical and morphological study

Preparations of rat-liver mitochondria catalyze the oxidation of exogenous NADH by added cytochrome c or ferricyanide by a reaction that is insensitive to the respiratory chain inhibitors, antimycin A, amytal, and rotenone, and is not coupled to phosphorylation. Experiments with tritiated NADH are described which demonstrate that this "external" pathway of NADH oxidation resembles stereochemically the NADH-cytochrome c reductase system of liver microsomes, and differs from the respiratory chain-linked NADH dehydrogenase. Enzyme distributation data are presented which substantiate the conclusion that microsomal contamination cannot account for the rotenone-insensitive NADH-cytochrome c reductase activity observed with the mitochondria. A procedure is developed, based on swelling and shrinking of the mitochondria followed by sonication and density gradient centrifugation, which permits the separation of two particulate subfractions, one containing the bulk of the respiratory chain components, and the other the bulk of the rotenone-insensitive NADH-cytochrome c reductase system. Morphological evidence supports the conclusion that the former subfraction consists of mitochondria devoid of outer membrane, and that the latter represents derivatives of the outer membrane. The data indicate that the electron-transport system associated with the mitochondrial outer membrane involves catalytic components similar to, or identical with, the microsomal NADH-cytochrome b₅ reductase and cytochrome b₅.     

玉山笔石(Yushanograptus)——江西玉山宁国页岩组中的一个新笔石属

本文所讨论的材料是笔者之一(韩乃仁)于1961年夏在江西玉山李家棚附近的下奥陶统宁国页岩组中采得的(野外号码:F61001),代表一个新属新种,兹取名为“分离玉山笔石”(Yushanograptus separatus gen.et sp.nov.)。玉山笔石的特点是两个原始枝(横索)很长,分枝方式属于稜笔石式(穆恩之,1953,1956)。其尚未分枝的幼年时期,和一些纤细的对笔石,如Didymograptus gracilis T(?)rn-quist,D.congnatus Harris et Thomas 等,非常相似,每一原始枝在生长了11—12个胞管之后才开始正分枝,连续到六级以上。这种原始枝特长的特征,与联笔石(Zygograptus)相似,但分枝的形式不同。联笔石的分枝为枝笔石式,而我们的新属的分枝则为左右相间     

马铃薯二次生长原因的初步观察

马铃薯二次生长所产生的次生块茎、子薯、畸型薯和发芽薯,不仅影响食用品质,而且也降低商品价值(见图1)。这种现象在世界各地都有发生,因此国外早就做过这方面的研究,特别是日本,在1945年以后     

Studies on Cellulose Synthesis by a Cell-free Oat Coleoptile Enzyme System: Inactivation by Airborne Oxidants

Particulate cell wall polysaccharide synthetase from oat coleoptiles could use either guanosine diphosphate glucose or uridine diphosphate glucose; the latter was a much more effective glucose donor. The neutral polymer derived from uridine diphosphate glucose utilization yielded, after cellulase digestion, mostly cellobiose and to a lesser extent a substance tentatively identified as a mixed-linkage β1,4 = β1,3-trisaccharide; only cellobiose was found after guanosine diphosphate glucose utilization. The uridine diphosphate glucose utilizing system was inactivated by peroxyacetyl nitrate treatment of intact tissue and to a lesser extent by ozone treatment suggesting that this system is a possible site of interference with cellulose and non-cellulosic glucan biosynthesis in vivo. Direct treatment of the enzyme in vitro by peroxyacetyl nitrate, iodoacetamide or p-chloromercuribenzoate also inactivated the enzyme, indicating that the mechanism of inactivation possibly involves reaction with sulfhydryl groups.     

周口店第一地点粪化石的初步观察

从1964年起,我们整理了周口店北京猿人化石产地(周口店第一地点)的粪化石,以及我国其他化石地点,如广西柳城巨猿洞里的一些同类材料。在整理工作中,清理出周口店遗址现有的粪化石,除破碎的外,约有1500枚左右。在遗址目前发掘到达的40米厚的堆积物剖面中,它们和其他化石一起,占据了从底部到上部的好几个层位,如第10层,第8—9层,第6层等。这些标本,有时密集成层,也有的是较零星的分布的。     

广东棉花害虫翠纹金钢钻(Earias fabia Stall)的研究

广东全省棉田普遍发生翠纹金钢钻,阳江县平岗农场,1957年数百苗棉田,被害很严重,蕾铃被害率达95—100％,是广东棉区威胁最大的害虫之一。因此我们进行了生活史和防治试验的研究,兹分述如下: 一、生活史观察 1958年在石牌本所棉田设置虫场饲养,从4月12