Effects of lithium salts on the behaviour and the orcadian system of Mesocricetus auratus W.

Abstract

LiCl (195 μg/g body weight and day) reduces water uptake in Syrian hamsters by 40%. Sleep duration is increased from 50% per day to 60% per day. Other behavioural items are hardly influenced. Shortening and lengthening of the circadian period was induced by Li⁺ in individual hamsters, but the mean period of the population was not changed. The upper limit of entrainment is increased by Li⁺.     

On the seasonal distribution of sunspot frequency

Abstract

Using the Zürich sunspot data, the seasonal distribution of all sunspot‐groups and of all new‐formed groups from 1938 to the last solar minimum in 1976 was investigated.

It is shown that there exist different distributions for the northern and southern solar hemisphere with maxima in the third and second quarter of the years, respectively, and seasonal differences in the north‐south asymmetry.

These results confirm the presumption of an influence of interstellar matter on solar activity.     

Circadian Rhythms of Plasma Concentrations of Na+ and K+ and Their Urinary Excretion in Normal and Diabetic Rats

The effects of streptozotocin induced diabetes (50 mg/Kg) on the circadian rhythms in the excretion of sodium and potassium as well as their plasma concentration rhythms were investigated. Control (C) and diabetic (D) rats were studied during a light-dark (12h:12h) cycle and fed ad libitum. Statistically significant circadian rhythms were found for sodium and potassium excretion in C rats. The orthophases of both rhythms occurred in the dark phase, the potassium one occurring before that of sodium. In D rats there is increased excretion of both sodium and potassium with the rhythmicity maintained for sodium excretion only, which has an earlier orthophase than in the C rats. Plasma sodium and potassium concentrations showed a statistically significant circadian pattern in C rats, with orthophase in the light phase. This rhythmicity only appears in plasma potassium concentration for D rats, with orthophase at the end of the dark phase. The results in diabetic rats may suggest that the glomerular filtration rate (GFR) and/or tubular reabsorption rhythms are still contributing to the sodium excretory rhythm, and that the loss of the circadian rhythm in sodium plasma concentration has no influence on the sodium excretion rhythm. Nevertheless, the loss of the potassium excretion rhythm may suggest a disruption of the variations in the secretory process, as this excretion seems to be independent of the plasma potassium concentration rhythm, which is not lost in D rats.     

Activity rhythms of enzymes in human red blood cell suspensions

Abstract

We have established the presence of a rhythm in the activity of 4 enzymes in in‐vitro cell suspensions of human red blood cells. Glucose 6‐phosphate dehydrogenase and glutamate oxaloacetate transaminase demonstrated semicircadian patterns of activity, while acid phosphatese and acetylcholine esterase exhibited circadian activity rhythms. The ratios between the highest to lowest activities varied from 2:1 to 10:1 among the various enzymes. The affinity of glucose 6 phosphate dehydrogenase to its substrate and coenzyme remained constant throughout the cycle. No evidence was obtained for the presence of a soluble inhibitor at the lower levels of the activity. Sonication of hemolysates with low glucose 6 phosphate dehydrogense activity yielded additional activity comparable to that of the peak activity. Sonication of hemolysates from the time of the peak activity did not change the original activity. The observations point to a role of the cell membrane in the biological clock.     

A change in the pattern in circadian running‐wheel activity after lesions of the intergeniculate leaflet and ventral lateral geniculate nucleus in the Syrian hamster

Abstract

The suprachiasmatic nuclei (SCN) contain the endogenous mammalian circadian pacemaker, which generates the circadian rhythm in locomotor activity. In Syrian hamsters with free‐running rhythms, the onset of running‐wheel activity is very precise and predictable while the end (offset) is more variable. From the thalamic intergeniculate leaflet (IGL) and the ventral lateral geniculate nucleus (vLGN) a projection to the SCN originates. Animals with a lesion aimed at the IGL/vLGN and sham‐and unoperated controls were kept in continuous darkness. With linear regression, lines were fitted through 10 successive onsets and offsets of activity and the mean deviation of the onsets and offsets from the fitted lines was determined. Animals with a complete or partial lesion of the IGL/vLGN had a smaller mean deviation of the circadian activity offset from the fitted regression line (0.313 h) compared with the grouped control animals (0.678 h). To test the difference statistically, we compared the sum of the square residuals of the circadian offsets between the groups. This difference was highly significant (F(69,64)=4.16, p<0.0001), which indicates that animals with a lesion of the IGL/ vLGN have a less variable circadian offset of running‐wheel activity. No differences were observed in the variability in the circadian onset of locomotor activity between experimental and control animals. It is concluded that the IGL/vLGN influence the variability of the offset of the circadian running‐wheel activity.     

Exploration of swapping enzymatic function between two proteins: A simulation study of chorismate mutase and isochorismate pyruvate lyase

The enzyme chorismate mutase EcCM from Escherichia coli catalyzes one of the few pericyclic reactions in biology, the transformation of chorismate to prephenate. The isochorismate pyruvate lyase PchB from Pseudomonas aeroginosa catalyzes another pericyclic reaction, the isochorismate to salicylate transformation. Interestingly, PchB possesses weak chorismate mutase activity as well thus being able to catalyze two distinct pericyclic reactions in a single active site. EcCM and PchB possess very similar folds, despite their low sequence identity. Using molecular dynamics simulations of four combinations of the two enzymes (EcCM and PchB) with the two substrates (chorismate and isochorismate) we show that the electrostatic field due to EcCM at atoms of chorismate favors the chorismate to prephenate transition and that, analogously, the electrostatic field due to PchB at atoms of isochorismate favors the isochorismate to salicylate transition. The largest differences between EcCM and PchB in electrostatic field strengths at atoms of the substrates are found to be due to residue side chains at distances between 0.6 and 0.8 nm from particular substrate atoms. Both enzymes tend to bring their non‐native substrate in the same conformation as their native substrate. EcCM and to a lower extent PchB fail in influencing the forces on and conformations of the substrate such as to favor the other chemical reaction (isochorismate pyruvate lyase activity for EcCM and chorismate mutase activity for PchB). These observations might explain the difficulty of engineering isochorismate pyruvate lyase activity in EcCM by solely mutating active site residues.     

TSHR蛋白在宫颈癌的表达及其与HPV-16感染的关系

目的研究促甲状腺激素受体（TSHR）在子宫颈癌组织的表达及其与乳头瘤病毒（HPV－16）的关系。方法应用免疫组织化学链霉菌抗生物素过氧化物酶（SP）法检测79例子宫颈癌和30例子宫颈炎组织HPV－16与TSHR蛋白表达。79例癌症患者中病理分级〈Ⅱ级33例,≥Ⅱ级46例;病理分期〈Ⅱ期56例,≥Ⅱ期23例;无淋巴结转移66例,有淋巴结转移13例;肿瘤大小〈3cm44例,肿瘤大小≥3cm35例。结果HPV－16在子宫颈癌表达率55．70％明显高于宫颈炎5％（P〈0．05）,TSHR在子宫颈癌表达率68．35％明显高于宫颈炎26．67％（P〈0．05）。HPV－16表达与肿瘤的大小、肿瘤分级、分期、淋巴结转移不相关。TSHR表达与肿瘤的大小呈正相关,P〈0．05,与肿瘤分级、分期及淋巴结转移不相关。HPV－16与TSHR在宫颈癌表达呈正相关。结论HPV感染对宫颈癌病变起到强烈的预警作用。TSHR不仅在甲状腺滤泡上皮细胞表达,在子宫颈癌细胞也表达,TSHR过表达能促进宫颈细胞的异常增殖,其异常功能可能是恶性肿瘤特定的临床表型。HPV与TSHR在子宫颈癌变过程中起协同作用。     

芦丁的资源、药理及主要剂型研究进展

芦丁广泛存在于多种天然植物如槐米、苦荞麦、尤曼桉中,在医药、日化、食品等领域有广泛的应用,近年来已成为研究热点.芦丁具有多种生理功能,对人体各个器官均有保护作用,如清除自由基、促进成骨细胞的生长、降低血糖、抑制结肠癌和前列腺癌等.本文对芦丁的资源来源、药理作用和剂型进行了简述.     

北部湾近海珊瑚礁区系沉积物抗菌活性放线菌类群

通过对大肠埃希菌和枯草芽胞杆菌抗菌活性初步筛选,从北部湾近海珊瑚礁区5个沉积物样品中成功分离得到51株具有不同抗菌活性的放线菌,其中9株具有较强抗菌能力。根据这9株放线菌的菌落和孢子形态,可确定它们都属于链霉菌属。 RAPD-PCR分析表明这9株放线菌为6种不同类型,16S rDNA序列和系统发生树分析表明,9株放线菌可划分到4个大的类群6种不同类型,且结果显示RAPD-PCR聚类分析与16S rDNA序列聚类分析的结果具有较大的一致性。生理生化鉴定结果表明,分离株与亲缘关系最近的放线菌模式菌株的生理生化特征均存在差异,这说明分离株为放线菌新种的可能性比较大。这6种放线菌具有较为广谱的抑菌活性,并且抑菌活性均存在一定的差异,说明其可能分泌出多种结构功能不同的活性次生代谢产物。研究结果表明,广西北部湾近海珊瑚礁区系沉积物蕴藏着丰富的可供药物开发的放线菌资源。     

Ecology and Behaviour of Burton's Legless Lizard(Lialis burtonis,Pygopodidae) in Tropical Australia

The elongate, functionally limbless flap-footed lizards(family Pygopodidae) are found throughout Australia, ranging into southern New Guinea. Despite their diversity and abundance in most Australian ecosystems, pygopodids have attracted little scientific study. An intensive ecological study of one pygopodid, Burton's legless lizard(Lialis burtonis Gray 1835), was conducted in Australia's tropical Northern Territory. L. burtonis eats nothing but other lizards, primarily skinks, and appears to feed relatively infrequently(only 20.8% of stomachs contained prey). Ovulation and mating occur chiefly in the late dry-season(beginning around September), and most egg-laying takes place in the early to middle wet-season(November–January). Females can lay multiple clutches per year, some of which may be fertilised with stored sperm. Free-ranging L. burtonis are sedentary ambush foragers, with radio-tracked lizards moving on average 5 m/day. Most foraging is done diurnally, but lizards may be active at any time of day or night. Radiotracked lizards were usually found in leaf-litter microhabitats, a preference that was also evident in habitat-choice experiments using field enclosures. Lizards typically buried themselves in 6–8 cm of litter; at this depth, they detect potential prey items while staying hidden from predators and prey and avoiding lethally high temperatures.