34S/32S and 18O/16O Fractionation During Sulfur Disproportionation by Desulfobulbus propionicus

In the present study, coupled stable sulfur and oxygen isotope fractionation during elemental sulfur disproportionation according to the overall reaction: 4H₂O + 4S^? → 3H₂S + SO₄ ^{2 ?} + 2H⁺, was experimentally investigated for the first time using a pure culture of the sulfate reducer Desulfobulbus propionicus at 35^?C. Bacterial disproportionation of elemental sulfur is an important process in the sulfur cycle of natural surface sediments and leads to the simultaneous formation of sulfide and sulfate. A dual-isotope approach considering both sulfur and oxygen isotope discrimination has been shown to be most effective in evaluating specific microbial reactions. The influence of iron- and manganese bearing-solids (Fe(II)CO₃, Fe(III)OOH, Mn(IV)O₂) acting in natural sediments as scavengers for hydrogen sulfide, was considered, too. Disproportionation of elemental sulfur was observed in the presence of iron solids at a cell-specific sulfur disproportionation rate of about 10^{? 9.5± 0.4} μ mol S^? cell^{? 1} h^{? 1}. No disproportionation, however, was observed with MnO₂. In the presence of iron solids, newly formed sulfate was enriched in ¹⁸ O compared to water by about +21‰ (≡ ? _H2O ), in agreement with a suggested oxygen isotope exchange via traces of intra- or extracellular sulfite that is formed as a disproportionation intermediate. Dissolved sulfate was also enriched in ³⁴S compared to elemental sulfur by up to +35%. Isotope fractionation by Desulfobulbus propionicusis highest for all disproportionating bacteria investigated, so far, and may impact on the development of isotope signals at the redox boundary of surface sediments.     

Microsatellite markers uncover cryptic species of Odontotermes (Termitoidae: Termitidae) from Peninsular Malaysia

Termites from the genus Odontotermes are known to contain numerous species complexes that are difficult to tell apart morphologically or with mitochondrial DNA sequences. We developed markers for one such cryptic species complex, that is, Odontotermes srinakarinensis sp. nov. from Maxwell Hill Forest Reserve (Perak, Malaysia), and characterised them using a sample of 41 termite workers from three voucher samples from the same area. We then genotyped 150 termite individuals from 23 voucher samples/colonies of this species complex from several sites in Peninsular Malaysia. We analysed their population by constructing dendograms from the proportion of shared-alleles between individuals and genetic distances between colonies; additionally, we examined the Bayesian clustering pattern of their genotype data. All methods of analysis indicated that there were two distinct clusters within our data set. After the morphologies of specimens from each cluster were reexamined, we were able to separate the two species morphologically and found that a single diagnostic character found on the mandibles of its soldiers could be used to separate the two species quite accurately. The additional species in the clade was identified as Odontotermes denticulatus after it was matched to type specimens at the NHM London and Cambridge Museum of Zoology.     

Isolation and Characterization of Antitumor Lipopolysaccharide from Proteus mirabilis

Systematic isolation of the cell constituents of Proteus mirabilis RMS–203 was performed to find out localization of antitumor principle only in the lipopolysaccharide (LPS) layer of the cell wall fraction.

LPS with strong antitumor activity was extracted from P. mirabilis RMS–203 by phenol-water method followed by purification on DEAE-Sephadex A–50 column chromatography.

The main components of purified LPS were galactose, hexosamine, 2-keto-deoxy-octonic acid (KDO), myristic acid, β-hydroxymyristic acid and α,ε-diaminopimelic acid.

The minimal effective dose of LPS against Ehrlich solid carcinoma in mice was 0.1~1.0 μg/mouse. LD₅₀ in mice and pyrogenicity in rabbits were 28 mg/kg and 10^?3–10^?5 μg/rabbit, respectively.     

CONTRIBUTION OF CIRCADIAN PHYSIOLOGY AND SLEEP HOMEOSTASIS TO AGE-RELATED CHANGES IN HUMAN SLEEP

The circadian pacemaker and sleep homeostasis play pivotal roles in vigilance state control. It has been hypothesized that age-related changes in the human circadian pacemaker, as well as sleep homeostatic mechanisms, contribute to the hallmarks of age-related changes in sleep, that is, earlier wake time and reduced sleep consolidation. Assessments of circadian parameters in healthy young (～20–30 years old) and older people (～65–75 years old)—in the absence of the confounding effects of sleep, changes in posture, and light exposure—have demonstrated that an earlier wake time in older people is accompanied by about a 1h advance of the rhythms of core body temperature and melatonin. In addition, older people wake up at an earlier circadian phase of the body temperature and plasma melatonin rhythm. The amplitude of the endogenous circadian component of the core body temperature rhythm assessed during constant routine and forced desynchrony protocols is reduced by 20–30% in older people. Recent assessments of the intrinsic period of the human circadian pacemaker in the absence of the confounding effects of light revealed no age-related reduction of this parameter in both sighted and blind individuals. Wake maintenance and sleep initiation are not markedly affected by age except that sleep latencies are longer in older people when sleep initiation is attempted in the early morning. In contrast, major age-related reductions in the consolidation and duration of sleep occur at all circadian phases. Sleep of older people is particularly disrupted when scheduled on the rising limb of the temperature rhythm, indicating that the sleep of older people is more susceptible to arousal signals genernpated by the circadian pacemaker. Sleep-homeostatic mechanisms, as assayed by the sleep-deprivation–induced increase of EEG slow-wave activity (SWA), are operative in older people, although during both baseline sleep and recovery sleep SWA in older people remains at lower levels. The internal circadian phase advance of awakening, as well as the age-related reduction in sleep consolidation, appears related to an age-related reduction in the promotion of sleep by the circadian pacemaker during the biological night in combination with a reduced homeostatic pressure for sleep. Early morning light exposure associated with this advance of awakening in older people could reinforce the advanced circadian phase. Quantification of the interaction between sleep homeostasis and circadian rhythmicity contributes to understanding age-related changes in sleep timing and quality. (Chronobiology International, 17(3), 285–311, 2000)     

Synthesis of Annonaceous Acetogenins from Muricatacin

Synthetic studies of annonaceous acetogenins starting from (?)-muricatacin (1a) or (+)-muricatacin are described, involving (?)-muricatacin (1a), mono-THF acetogenin, solamin (2), reticulatacin (3), (15R, 16R, 19S, 20S)-cis-solamin (4a) and (15S, 16S, 19R, 20R)-cis-solamin (4b), non-adjacent bis-THF acetogenin, 4-deoxygigantecin (5), and epoxide-bearing acetogenin, (15S, 16R, 19S, 20R)-diepomuricanin (6a).     

Anaerobic Elemental Sulfur Reduction by Fungus Fusarium oxysporum

Reduction of inorganic sulfur compounds by the fungus Fusarium oxysporum was examined. When transferred from a normoxic to an anoxic environment, F. oxysporum reduced elemental sulfur to hydrogen sulfide (H₂S). This reaction accompanied fungal growth and oxidation of the carbon source (ethanol) to acetate. Over 2-fold more of H₂S than of acetate was produced, which is the theoretical correlation for the oxidation of ethanol to acetate. NADH-dependent sulfur reductase (SR) activity was detected in cell-free extracts of the H₂S-producing fungus, and was found to be up-regulated under the anaerobic conditions. On the other hands both O₂ consumption by the cells and cytochrome c oxidase activity by the crude mitochondrial fractions decreased. These results indicate that H₂S production involving SR was due to a novel dissimilation mechanism of F. oxysporum, and that the fungus adapts to anaerobic conditions by replacing the energy-producing mechanism of O₂ respiration with sulfur reduction.     

Effect of Kluyveromyces marxianus YIT 8292 Crude Cell Wall Fraction on Serum Lipids in Normocholesterolemic and Mildly Hypercholesterolemic Subjects

The hypocholesterolemic effects of Kluyveromyces marxianus YIT 8292 crude cell wall (KM-CW) were examined. In pilot studies, KM-CW tablets were administered to mildly hypercholesterolemic subjects at doses of 8.0, 4.0, 2.0, or 1.0 g/d for 4 weeks. Total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) decreased at doses above 2.0 and 4.0 g/d, respectively. Further, we examined the effect of intake of yogurt containing 3.0 or 4.0 g of KM-CW/d for 8 weeks in normal and hypercholesterolemic subjects in a double-blind placebo-controlled study. The intake of either of the KM-CW-containing yogurts was associated with significantly improved TC and LDL-C in hypercholesterolemic subjects, but had no effect on these levels in normal subjects. TC was significantly lower at week 8 in the hypercholesterolemic subjects who ingested yogurt containing 3.0 or 4.0 g of KM-CW than in those who consumed placebo yogurt. Intake of KM-CW might contribute to the prevention of hypercholesterolemia.     

正交设计和动态过程优化两面针超声提取工艺

以总生物碱提取率为指标,先用正交试验优化两面针的超声提取工艺,再动态过程精选提取工艺。最佳工艺条件为:复合酶预处理后,以体积分数60%乙醇(盐酸5 g/L)超声(250 W)提取3次,第1次以10倍量溶剂提取15 min,第2次以4倍量溶剂提取12 min,第3次以3倍量溶剂提取9 min,总生物碱提取率87.80%。该工艺高效、节能、省时,为工业生产奠定了实验基础。