Saliva of the soft tick, Ornithodoros moubata, contains anti-platelet and apyrase activities.

1. Pilocarpine-induced saliva of the soft tick Ornithodoros moubata inhibits platelet aggregation induced by ADP or collagen, even when diluted 2000 times into platelet rich plasma. 2. Saliva contains apyrase (ATP-diphosphohydrolase) activity, which has an optimal pH of 7.0 for ADP and of 8.0 for ATP hydrolysis, respectively. Both Ca2+ and Mg2+ activate the reactions. 3. The mean specific activities for ATP and ADP hydrolysis at pH 7.5 were 0.97 and 0.74 mumoles orthophosphate/min/mg protein. 4. These results, which demonstrate for the first time such activities in the saliva of soft ticks, support the hypothesis that the saliva of blood sucking arthropods serves an anti-hemostatic role during feeding and that large amounts of salivary apyrase activity have evolved independently in hematophagous arthropods.     

Enzyme activities in human endometrium, myometrium and leiomyomas of the uterus.

Certain selected enzymes of carbohydrate metabolism were measured in samples of endometrium and myometrium from women who were premenopausal or postmenopausal. In addition, a number of samples of leiomyoma were obtained and assayed. Activities of several enzymes were higher in endometrium from premenopausal women compared to those in postmenopausal women; activities in myometrium were similar regardless of menopausal status. The activities of G6PD, ICD and GPI appeared to be lower in leiomyoma samples versus myometrial samples from premenopausal women; however, these differences were not apparent when enzyme activity was expressed per milligram protein.     

消息与动态

“特里尼尔(Trinil)爪哇人发现一百周年国际讨论会在印尼泗水召开” “Trinil瓜哇人发现一百周年(1891—1991)”国际讨论会于1991年11月18日至21日在印尼东爪哇省泗水(surabaya)召开,出席会议的除印尼学者外,还有来自澳大利亚、法国、菲律宾、中国、印度、马来西亚、南非、荷兰、埃塞俄比亚、肯尼亚等12个国家的十六位代表,提交的论文有30篇。 会议开幕式和展览在泗水世界商业中心(WTC)举行。南非的Tobias和印尼的Jacob分别作了“直立人的一百周年和对古人类学上的影响”和“Trinil发现的意义”的报告。中国的     

Mechanism of anticholinesterase activities of cardiotoxin, protamine and polylysine.

Cardiotoxin, protamine and polylysine are potent inhibitors of various cholinesterases. CaCl2 and MgCl2 overcome the inhibition. The order of addition of the inhibitor and the protecting agent (MgCl2) influences the final degree of the inhibition observed. These findings suggest that cardiotoxin, protamine and polylysine inhibit cholinesterases by the ionic binding of their basic groups with the anionic sites of cholinesterase molecules.     

Comparison of the steroidogenic and melanotropic activities of corticotropin, alpha-melanotropin and analogs with their lipolytic activities in rat and rabbit adipocytes.

The ability of alpha-melanotropin and a series of synthetic peptides related to adrenocorticotropin (ACTH) to stimulate steroidogenesis in isolated rat adrenal cells, melanin dispersion in frog melanophores and lipolysis in rat and rabbit fat cells have been studied. It was found that the steroidogenic activity closely paralleled the lipolytic activity of these peptides in rat fat cells, whereas the melanocyte stimulating activity paralleled the lipolytic activity in rabbit fat cells. These results indicate that the structural requirements for stimulating steroidogenesis in isolated rat adrenal cells and lipolysis in isolated rat fat cells are quite similar. The structural features required for eliciting lipolysis in rabbit fat cells appear to be very similar to those necessary for stimulating frog melanophores. The possibility that regulation of lipid metabolism in the rabbit may be a new function acquired by melanotropin is discussed.     

Isolation, characterization, and antitumor activities of the cell wall polysaccharides from Elsinoe leucospila.

A cell-wall preparation from the cells of Elsinoe leucospila, which produces elsinan extracellularly when grown on sucrose or glucose-potato extract medium, was fractionated systematically. The heteropolysaccharide that was released by treatment with Actinase E digestion, comprised D-mannose, D-galactose, and D-glucose (molar ratio, 1.5:1.0:0.1). Methylation, mild acid hydrolysis, and 13C-NMR studies suggested that the polysaccharide contains a backbone of alpha-(1----6)-linked D-mannose residues having two kinds of side chains, one attached at the O-4 with single or short beta-(1----6)-linked D-galactofuranosyl residues, and the other attached at O-2 with short side chains, most probably, of alpha-(1----3)-linked D-mannopyranosyl residues. A moderately branched D-glucan fraction, obtained from the cold alkali extract, was fractionated to give an antitumor-active purified beta-(1----3)-glucan having branches of single beta-D-glucosyl groups, one out of eight D-glucose residues being substituted at the O-6.     

Postinspiratory neuronal activities during behavioral control, sleep, and wakefulness.

Cells that discharge in early expiration and inhibit other respiratory cells purportedly cause a separate phase of the respiratory cycle that has been named "postinspiration." Our objective was to study these postinspiratory cells in the intact unanesthetized cat during sleep, wakefulness, and behavioral inhibition of inspiration, but we were unable to find cells with strong and consistent activity confined to early expiration. Instead, we found that various cell types were active in early expiration. They included inspiratory-expiratory phase-spanning cells, retrofacial augmenting expiratory cells with bursts in early expiration, retrofacial decrementing expiratory cells, tonic expiratory cells, and cells with variable activity in the early part of expiration. Just as the cell types active during early expiration were heterogeneous so too were their activities during behavioral inhibition of inspiration and during sleep. These results suggest that the state of early expiration is determined by many different cell types rather than a single class of postinspiratory cells.     

Characterization of the membrane proteins of rat liver lysosomes. Composition, enzyme activities and turnover.

Lysosomes prepared from the livers of untreated rats and from the livers of rats injected with either Triton WR-1339 or dextran yielded membranes that were similar in both polypeptide composition and activities of ATPase and acid 5'-nucleotidase. The administration of Triton WR-1339 (and dextran) resulted in an increase in ATPase activity of liver homogenates that was associated with a parallel increase in the ATPase activity of the lysosomal membrane. On the other hand, plasma membranes appear to be different from lysosomal membranes with respect to polypeptide composition and enzyme activities. The ATPase activity of lysosomal membranes is not affected by ouabain and suramin, inhibitors of the plasma-membrane ATPase. The plasma-membrane alkaline 5'-nucleotidase has little activity at acid pH. Pulse-labelling of lysosomal membranes with [3H]fucose and with [3H]- and [14C]-leucine occurred rapidly, faster than labelling of plasma membranes. The labelling kinetics indicate that lysosomal membranes may be assembled independently of plasma membranes. These data suggest that, in liver, little bulk transport of plasma membrane to lysosomes takes place, and lysosomal-membrane proteins may not be derived from those of plasma membranes.     

Assessment of the molluscicidal activities of Tribromosalan, Cartap and Chlorothalonil against Oncomelania hupensis.

Molluscicidal activities of Tribromosalan, Cartap and Chlorothalonil were evaluated in the laboratory and the field against Oncomelania hupensis, the intermediate host of Schistosoma japonicum in China. The three chemicals were very effective against O. hupensis in the laboratory. The molluscicidal activities found in the field trials suggest that Tribromosalan and Cartap may be used as practical molluscicides. Dosage of 10 g/m2 of Tribromosalan in spring only and 20 g/m2 of Cartap in both spring and autumn would be recommendable as practical mollusciciding doses for the control of O. hupensis.     

液体培养条件下槐生多年卧孔菌、微酸多年卧孔菌和白蜡多年卧孔菌的抗氧化活性研究

槐生多年卧孔菌Perenniporia robiniophila、微酸多年卧孔菌Perenniporia subacida和白蜡多年卧孔菌Perenniporia fraxinea均属于药用真菌,具有较高的应用价值。本研究将这3种药用真菌进行液体培养,测定此过程中的漆酶活性、多酚含量、超氧化物歧化酶(superoxide dismutase,SOD)活性、总抗氧化能力(total antioxidant capacity,T‐AOC)、过氧化氢酶(catalase,CAT)活性、抑制羟自由基能力(restraining ability to hydroxyl free radicals,RAHFR)和1,1‐二苯基‐2‐三硝基苯肼(1,1‐diphenyl‐2‐picrylhydrazyl,DPPH)自由基清除能力。结果显示,所选取的3种多年卧孔菌均具有抗氧化活性,且该活性与菌株自身的生长状况、次级代谢产物分泌及降解酶活性等密切相关。其中,微酸多年卧孔菌分泌的漆酶活性最高,出现峰值时间最早,第6天时酶活可达2.51U/m L。槐生多年卧孔菌在液体培养过程中分泌多酚、T‐AOC和CAT的能力最强,于第2天、第12天和第8天时分别达1.54mg/m L、2.59U/m L和7.71U/m L。此外,该菌株对羟自由基及DPPH自由基的清除能力也较强,在第10天和第2天分别为78.42U/m L和26.65%。而白蜡多年卧孔菌仅分泌SOD的能力最强,第2天时酶活为1.87U/m L。相比之下,3种多年卧孔菌中尤其以槐生多年卧孔菌的抗氧化活性最高,微酸多年卧孔菌次之,最后是白蜡多年卧孔菌。     

Changes in the activities of enzymes, especially lactate dehydrogenase, in endotoxin-poisoned mice.

Carbohydrate metabolic disorders were investigated by means of enzyme activities in mice (ddYS) injected intraperitoneally with endotoxin from Salmonella typhimurium. The mice exhibited hyperglycemia 2 hr after administration of endotoxin and hypoglycemia at 18 hr. Activity of hepatic phosphorylase in the endotoxin-poisoned mice at 2 hr was slightly higher than that in the control mice, whereas the level of this activity was not significantly different from that in the controls after 18 hr. Glucose-6-phosphatase activity in the poisoned mice increased by 2 hr after injection, but decreased by 18 hr. The blood lactate level in the poisoned mice transiently decreased until 3 hr after injection, but the mice exhibited a marked lactacidemia by 8–24 hr. The time course of lactate dehydrogenase (LDH) activity in various tissues was examined in mice injected with endotoxin. The activity of hepatic LDH declined to about two-thirds of that of the control mice after 16 hr, and was restored to the normal level by 48 hr. LDH in the cardiac muscle was markedly activated (by about 37%) in the early period (3–6 hr) after administration of endotoxin, and this activity gradually declined. However, the activity of LDH in the skeletal muscle showed a tendency similar to the rise and fall of the levels of blood lactate, and was restored to the normal value at 72 hr after injection. On the other hand, the serum LDH activity in the poisoned mice increased about 1.75-fold by 16 hr after injection. Mice injected with endotoxin exhibited a leakage of the isozymes LDH 3 and 5, but the origin of the leakage is uncertain. Similar elevation in the activities of transaminases (GPT and GOT) and malate dehydrogenase was found in the mouse serum at 16 hr after injection of endotoxin.     

Biological activities of analogues of lipid A based chemically on the revised structural model. Comparison of mediator-inducing, immunomodulating and endotoxic activities

Lipid A analogues were chemically synthesized based on the model structure recently revised, and biological activities of the analogues were tested. The analogue, (beta-1,6)-linked glucosamine disaccharide carrying ester-bound 3-hydroxytetradecanoic acids at 3 and 3' position of reducing and nonreducing glucosamine in addition to amide-bound 3-hydroxytetradecanoic acids and glycosidic-linked and ester-linked phosphate groups, showed much stronger activities for mediator inducing and immunomodulating as well as endotoxic activities than those exhibited by the previously synthesized analogues based on the old model. Among the activities tested, induction of interferon and tumor necrosis factor as well as mitogenicity, adjuvanticity and pyrogenicity were, however, not expressed so strongly as natural lipid A used as controls. In contrast, the analogue exhibited comparable activities to those of control lipid A in the test of lethal toxicity to mice and gelating activity of Limulus amebocyte lysate. Other synthetic analogues carrying a phosphate group showed comparable, slightly stronger or weaker activities depending on the test, but nonphosphorylated analogue exhibited no apparent or only very weak activities.     

Scatter factor and hepatocyte growth factor: activities, properties, and mechanism.

Scatter factor (SF) was first identified as a fibroblast-derived protein which disperses (i.e., "scatters") cohesive colonies of epithelium. SF-like proteins were found in human smooth muscle cell conditioned medium, amniotic fluid, and placental tissue. SFs markedly stimulate migration of epithelial, carcinoma, and vascular endothelial cell types at picomolar concentrations. Hepatocyte growth factors (HGFs) were originally described as platelet- and serum-derived proteins which stimulate hepatocyte DNA synthesis. Partial amino acid sequence data for mouse and human SFs indicate significant homology with HGFs. We used biological, biochemical, and immunological assays to evaluate and compare the activities, properties, and mechanisms of action of mouse SF, human SF (fibroblast or placenta derived), and recombinant human HGF (hrHGF). We report the following findings: (a) mouse SF exhibits species-related differences in biological activities relative to the human factors; (b) human SF and hrHGF show significant overlap in biological activities (i.e., hrHGF stimulates motility of multiple normal and carcinoma cell types, whereas human SF stimulates DNA synthesis in several normal cell types); (c) the three factors contain common antigenic determinants; and (d) all three proteins stimulate rapid phosphorylation of tyrosine residues on the c-met protooncogene protein product (the putative receptor for HGF) and on another protein with Mr 110,000. A few biological and immunological differences between human SFs and hrHGF were observed. These may reflect minor variations in amino acid sequence or posttranslational modification related to the sources of the factors. Taken as a whole, our findings suggest that by structural, functional, immunological, and mechanistic criteria, human SF and human HGF are essentially identical.     

Substrate DNA and cofactor regulate the activities of a multi-functional restriction-modification enzyme, BcgI.

The BcgI restriction-modification system consists of two subunits, A and B. It is a bifunctional protein complex which can cleave or methylate DNA. The regulation of these competing activities is determined by the DNA substrates and cofactors. BcgI is an active endonuclease and a poor methyltransferase on unmodified DNA substrates. In contrast, BcgI is an active methyltransferase and an inactive endonuclease on hemimethylated DNA substrates. The cleavage and methylation reactions share cofactors. While BcgI requires Mg2+and S -adenosyl methionine (AdoMet) for DNA cleavage, its methylation reaction requires only AdoMet and yet is significantly stimulated by Mg2+. Site-directed mutagenesis was carried out to investigate the relationship between AdoMet binding and BcgI DNA cleavage/methylation activities. Most substitutions of conserved residues forming the AdoMet binding pocket in the A subunit abolished both methylation and cleavage activities, indicating that AdoMet binding is an early common step required for both cleavage and methylation. However, one mutation (Y439A) abolished only the methylation activity, not the DNA cleavage activity. This mutant protein was purified and its methylation, cleavage and AdoMet binding activities were tested in vitro . BcgI-Y439A had no detectable methylation activity, but it retained 40% of the AdoMet binding and DNA cleavage activities.