三七中达马烷型皂甙的热不稳定性及酸水解产物

前人已证明人参和三七中富含的达马烷型人参皂甙在通常酸性水解下甙元即发生变化,而在弱酸(如50％醋酸,0.1N盐酸)条件下则形成次级皂甙。本文报道人参甙(ginseno-sides)和三七甙(notoginsenosides)的水溶液在水浴上加热亦分别形成相应的C-20位去糖基的次级皂甙。联系到人参和三七均有在蒸煮加工后C-20位去糖基皂甙收率增大的趋势,似可认为人参和三七中的这类皂甙有相当一部分是在生药的加工泡制以及提取过程中形成的次级皂甙,而不一定是植物体的原生成分。将人参甙Rb_1单体以酸水解,不仅得到主产物人参二醇(3),还分离到异去氢原人参二醇(5)、达马烷-20(22)-烯-3β,12β,26-三醇(6)、20(R)-达马烷-3β,12β,20,25-四醇(7)以及20(S)-和20(R)-原人参二醇(1、2)的混合物,从而认为这些微量成分与人参二醇一样均为达马烷型人参皂甙在酸性水解条件下C-20位糖基断裂后由真甙元的侧链转化形成的工作产物。     

The hemolymph coagulation system in invertebrate animals

A hemocyte lysate from horseshoe crab produced a gel, when exposed to Gram-negative bacterial endotoxins. This gelation reaction of the lysate, so-called Limulus test, has been widely employed as a simple and very sensitive assay method for endotoxins. Recent biochemical studies on the principle of Limulus test indicate that the hemocytes contain several serine protease zymogens, which constitute a coagulation cascade triggered by endotoxins, and that there is a (1 3)--d-glucan-mediated coagulation pathway which also results in the formation of gel. Up to now, six protein components, designated coagulogen, proclotting enzyme, factor B, factor C, factor G and anti-LPS factor, all of which are closely associated with the endotoxin-mediated coagulation pathway, have been purified and biochemically characterized. Among these components, the complete amino acid sequences of coagulogens isolated from one American and three Asian species of horseshoe crabs have been established. Moreover, the reconstitution experiment using the isolated clotting factors, C, B, proclotting enzyme and coagulogen in the presence of endotoxin, leads to the formation of coagulin get. Based on these results, we propose here a mechanism for the Limulus coagulation cascade.     

Role of hypothalamic histaminergic systems in the regulation of vigilance states in cats

We have studied the effects of local injections of histaminergic and antihistaminic drugs on the sleep-waking cycle in the cat. Microinjections of alpha-fluoromethylhistidine (alpha-FMH), a specific inhibitor of histidine decarboxylase, in the ventrolateral posterior hypothalamus, where histamine-immunoreactive neurons have been recently identified, resulted in a significant decrease in wakefulness (W) and increase in deep slow wave sleep (SWS). On the other hand, microinjections of SKF-91488 (Homodimaprit), a specific inhibitor of histamine-N-methyltransferase, increased W and decreased SWS and paradoxical sleep (PS). Microinjections of histamine also produced an increase of W, while this effect was abolished by pretreatment with mepyramine, an H1-histamine receptor antagonist.     

Regulation of sperm flagellar movement by protein phosphorylation and dephosphorylation

Flagellar motility of Triton models of sea urchin spermatozoa was reactivated by cyclic AMP-dependent protein kinase and a protein factor, termed motility activator, both of which were prepared from the detergent-extract of sea urchin spermatozoa. It was shown that phosphorylation of the motility activator by the protein kinase is necessary for the reactivation of flagellar motility [Ishiguro et al, J. Cell Biol. 92:777-782, 1982; Murofushi et al, in "Biological Functions of Microtubules and Related Structures," Academic Press, 1982]. Reactivating factor was also detected in a KCl-extract of the axoneme fraction devoid of the detergent-extractable materials. The activity of this factor was also cyclic AMP- and protein kinase-dependent. Furthermore, when freshly prepared Triton models were treated with phosphoprotein phosphatase prepared from bovine cardiac muscle, the flagellar motility was drastically suppressed. This inhibition of the motility was partially recovered by the addition of cyclic AMP and protein kinase to the phosphatase-treated models.     

Modulatory Action of Taurine on the Release of GABA in Cerebellar Slices of the Guinea Pig

Abstract: For the purpose of demonstrating the action of taurine as a neuromodulator in addition to its suggested neurotransmitter function, the effects of taurine and muscimol on the depolarization-induced Ca-dependent release of [³H]γ-aminobutyric acid (pH]GABA) and l -[³H]glutamate in cerebellar slices from guinea pigs were investigated. The release of [³H]GABA was found to be greatly decreased by a GABA agonist, muscimol, and by taurine, but not by glycine. The release of l -[³H]glutamate was little affected by taurine. The release of [³H]GABA was enhanced by bicuculline and strychnine, but not by picrotoxin, and the suppressive action of muscimol on the GABA release was antagonized by bicuculline, picrotoxin, and strychnine, suggesting the possible existence of presynaptic autoreceptors for GABA in the cerebellum. The suppressive action of taurine on the release of [³H]GABA, on the other hand, was blocked only by bicuculline. These results suggest that taurine reduced the release of [³H]GABA from cerebellar slices by acting on the GABA autoreceptors or, more likely, on other types of receptors that are sensitive to bicuculline. As a possible mechanism for this modulatory action of taurine, the blockade by this amino acid of the influx of Ca²⁺ into cerebellar tissues was tentatively suggested.     

Differential staining of insect neurons with nickel and cobalt

Pairs of neurons were differentially stained by intracellular injection of the divalent cations, nickel and cobalt. Pairs of neuronal tracts could be similarly labelled following immersion of their axon bundles in the markers described. Use of nickel and a 4 : 6 mixture of cobalt and nickel according to the protocols presented here revealed the morphology of cricket neuron processes as thin as 1 μm in diameter and yielded a favourable contrast between the cells marked, as well as with respect to the background of unstained tissue.     

Replication of Deoxyribonucleic Acid in Escherichia coli C Mutants Temperature Sensitive in the Initiation of Chromosome Replication

An Escherichia coli HF4704S mutant temperature sensitive in deoxyribonucleic acid (DNA) synthesis and different from any previously characterized mutant was isolated. The mutated gene in this strain was designated dnaH. The mutant could grow normally at 27 C but not at 43 C, and DNA synthesis continued for an hour at a decreasing rate and then ceased. After temperature shift-up, the increased amount of DNA was 40 to 50%. When the culture was incubated at 43 C for 70 min and then transferred to 27 C, DNA synthesis resumed after about 50 min, initiating synchronously at a fixed region on the bacterial chromosome. The initiation step in DNA replication sensitive to 30 mug of chloramphenicol per ml occurs synchronously before the resumption of DNA replication after the temperature shift-down, being completed about 30 min before the start of DNA replication. When the cells incubated at 27 C in the presence of 30 mug of chloramphenicol per ml after the temperature shift-down to 27 C were transferred to 43 C with simultaneous removal of the antibiotic, no resumption of DNA replication was observed. When the culture was returned to 43 C after being released from high-temperature inhibition at 30 min before the start of DNA replication, no recovery replication was observed; whereas at 20 min, the recovery of replication was observed. These results indicated that HF4704S was temperature sensitive in the initiation of DNA replication. Analysis of HF4704S, by an interrupted conjugation experiment, indicated that gene dnaH was located at about 64 min on the E. coli C linkage map. In E. coli S1814 (a K-12 derivative), which was a dnaH(ts) transductant from HF4704S (C strain) with phage P1, the mutated gene (dnaH) was demonstrated to be closely linked to the thyA marker by conjugation and P1 transduction experiments and to be distinct from genes dnaA through dnaG.