豚鼠冰水游泳应激后血浆、肾上腺髓质和脑内组织的亮—脑啡肽含量变化

豚鼠冰水游泳应激3min后,用放射免疫法测定血浆、肾上腺髓质和脑内三个脑区组织的亮—脑啡肽(Leu-enkephalin,LEK,)含量和血浆的血管紧张肽Ⅱ(Angiotensin Ⅱ,ATⅡ)浓度变化。结果表明:在冰水中游泳应激组豚鼠的血浆、肾上腺髓质、下丘脑和纹状体组织的LEK含量和血浆的ATⅡ浓度,均较对照组豚鼠明显升高(P值均<0.01)。提示:豚鼠在冰水中紧张、剧烈游泳后,可能激活了中枢神经和周围组织内的脑啡肽能神经元和血管紧张肽原酶—血管紧张肽Ⅱ系统,从而促进LEK和ATⅡ的释放增加。     

慢性蜜蜂麻痹病病毒核酸与蛋白质组分的研究

从自然感染的意大利麻痹病蜂(APis mellifera)头部,经二次差速离心与蔗糖梯度离心获得纯化的慢性蜜蜂麻痹病病毒(CBPV)。纯化的CBPV制备物感染正常蜜蜂,4天后出现典型的麻痹症状,接着死亡,平均死亡率分别为95％与100％。SDS-聚丙烯酰胺凝胶电泳分析,二次差速离心初步纯化的病毒制备物含有多条蛋白带,而蔗糖密度梯度纯化的病毒制备物仅含有单一的多肽带。5％、7.5％与10％SDS-聚丙烯酰胺凝胶电泳分析,均检测出一种病毒蛋白质,分子量大约为24,200道尔顿,而且不同凝胶浓度检测的蛋白质分子量相近。慢性蜜蜂麻痹病病毒核酸也用SDS-聚丙烯酰胺凝胶电泳分析,结果表明,凝胶中有5条带,对核酸酶敏感,证明该病毒含有5个单股RNA组分。对慢性蜜蜂麻痹病病毒的基因组结构进行了讨论。     

Specific binding of three neurotoxins with phospholipase A2 activity to synaptosomal membrane preparations from the guinea pig brain

Snake presynaptic toxins such as crotoxin, β-bungarotoxin and taipoxin block neuromuscular transmission through inhibiting the release of acetylcholine by their phospholipase A₂ activities. On the other hand, many other phospholipase A₂s show little neurotoxicity. It is likely that the difference lies in whether high affinity binding to nerve cell membranes exists or not. To test this idea, crotoxin, β-bungarotoxin and taipoxin were first radioactively labeled with Na(¹²⁵I) without loss of their neurotoxicity. Using the radioactive toxins we have found that each of the three showed specific binding to synaptosomal membranes from guinea pig brain. In contrast, we could not detect specific binding of a non-neurotoxic pancreatic phospholipase A₂. Crotoxin and taipoxin, but not β-bungarotoxin, also bound specifically to membrane preparation from other tissues. The binding of each toxin was not greatly affected by the other two toxins. The photoaffinity labeling technique has been used to obtain further information about the components which bind crotoxin. For this purpose, (¹²⁵I) crotoxin was derivatized with N-hydroxysuccinimidyl-4-azidobenzoate. Autoradiographic analysis of the membranes following photoirradiation in the presence of the modified crotoxin revealed that an 85K dalton component was preferentially covalently conjugated with the crotoxin analogue in a specific manner.     

伸展素在黄瓜胞壁中的转化及其与羟脯氨酸和异联酪氨酸的关系

用~(14)C-Pro和~3H_2-Tyr离体暗培养黄瓜子叶,发现细胞质、SECW和RCW中的Hyp/Pro和Idt/Tyr都随时间呈线性增加。这两种比值后两者高于前者,而两种比值增加速度之比在胞质部分最大、RCW中最小。表明在胞质和胞壁中都有Pro羟化和Tyr异联化过程,但羟化作用主要发生在胞质中,异联化主要在RCW中。 理化处理(高渗溶液和CHM)和放射性示踪证明胞质中存在HRGP库;它被分泌到胞壁后,先以离子键与壁结合,后转变为共价键与壁结合的伸展素。     

水分胁迫对植物线粒体结构和脯氨酸氧化酶活性的影响

水分胁迫期间,小麦幼苗芽鞘和棉花幼苗胚轴细胞内游离脯氨酸浓度增加;但复水后又恢复正常。电镜观察发现线粒体肿大,嵴消失。胞质中出现脂肪滴。气相层析技术分析,发现水分胁迫使线粒体脂肪酸组成及含量有明显变化;不饱和脂肪酸含量增加。随着水分胁迫时间的延长,脯氨酸氧化酶活性也明显下降。设想水分胁迫使线粒体结构和组分发生了不利于脯氨酸氧化酶活性表达的变化,因而抑制了酶活性。     

Gene structure and nucleotide sequence for rat cytochrome P-450c

Two clones from rat genomic libraries that contain the entire gene for rat cytochrome P-450c have been isolated. lambda MC4, the first clone isolated from an EcoR1 library, contained a 14-kb insert. A single 5.5-kb EcoR1 fragment from lambda MC4, the EcoR1 A fragment, hybridized to a partial cDNA clone for the 3' end of the cytochrome P-450c mRNA. This fragment was sequenced using the dideoxynucleotide chain termination methodology with recombinant M13 bacteriophage templates. Comparison of this sequence with the complete cDNA sequence of cytochrome P-450MC [Yabusaki et al. (1984) Nucleic. Acids Res. 12, 2929-2938] revealed that the EcoR1 A fragment contained the entire cytochrome P-450c gene with the exception of a 90-bp leader sequence. The gene sequence is in perfect agreement with the cDNA sequence except for two bases in exon 2. A second genomic clone, lambda MC10, which was isolated from a HaeIII library, contains the missing leading sequence as well as 5' regulatory sequences. The entire gene is about 6.1 kb in length with seven exons separated by six introns, all of the intron/exon junctions being defined by GT/AG. Amino- and carboxy-terminal information are contained in exons 2 and 7, respectively. These exons contain the highly conserved DNA sequences that have been observed in other cytochrome P-450 species. Potential regulatory sequences have been located both 5' to the gene as well as within intron I. A comparison of the coding information for cytochrome P-450c with the sequence of murine cytochrome P3-450 and rat cytochrome P-450d revealed a 70% homology in both the DNA and amino acid sequence, suggesting a common ancestral gene. Genomic blot analyses of rat DNA indicated that the 3-methylcholanthrene-inducible family of cytochrome P-450 isozymes is more limited in number compared to the phenobarbital-inducible isozymes. Cross-hybridization studies with human DNA suggest a high degree of conservation between rat cytochrome P-450c and its human homolog although gross structural differences do exist between the two genes.     

Uptake of free amino acids by the diatom,Melosira mediocris

Individual ¹⁴C-labelled amino acids are rapidly removed from dilute solution in artificial sea water (0.2 mol 1^–1) by suspensions of Meliosira medocris. The rate of disappearance of radioactivity corresponds closely to removal of primary amines as determined by measurement of the rate of decrease of fluorescamine-positive material. Net removal of naturally occurring free amino acids from the sea water habitat from which the alga was isolated is demonstrated using high performance liquid chromatography. Removal of amino acids from natural sources makes a significant contribution to the carbon requirements of the alga as well as supplying significant amounts of amino nitrogen.     

关于猫颌下腺神经支及其节前神经元的观察

用逆行溃变（Kohnstamm,1902;Yagita,et al.,1909;Torvik,1957）局部电刺激中枢（Chatfield,1942;Magoun et al.,1942;Wang,1943）等方法进行唾液中枢的定位,所得到结果很不一致。近年Satomi（1979）等用辣根过氧化酶（HRP）浸泡猫中间一面神经或鼓索神经,观察了脑干中逆行标记细胞的分布。但用HRP直接浸泡支配猫颌下腺的神经分支尚未见报道。此外,只见到关于鼓索神经纤维类别和数量的分析的光学显微镜研究（Foley,1945）,用光镜和电镜相结合分析颌下腺神经支中的纤