The effect of vitamin E on lipid peroxidation in the copper-deficient rat

The present study was designed to determine whether the supplementation of vitamin E in the copper-deficient diet would ameliorate the severity of copper deficiency in fructose-fed rats. Lipid peroxidation was measured in the livers and hearts of rats fed a copper-deficient diet (0.6 microg Cu/g) containing 62% fructose with adequate vitamin E (0.1 g/kg diet) or supplemented with vitamin E (1.0 g/kg diet). Hepatic lipid peroxidation was significantly reduced by vitamin E supplementation compared with the unsupplemented adequate rats. In contrast, myocardial lipid peroxidation was unaffected by the level of vitamin E. Regardless of vitamin E supplementation, all copper-deficient rats exhibited severe signs of copper deficiency, and some of the vitamin E-supplemented rats died of this deficiency. These findings suggest that although vitamin E provided protection against peroxidation in the liver, it did not protect the animals against the severity of copper deficiency induced by fructose consumption.     

Three-dimensional structure of the regular surface glycoprotein layer of Halobacterium volcanii from the Dead Sea

A three-dimensional reconstruction from electron micrographs of negatively stained cell envelopes of Halobacterium volcanii has revealed the structure of the surface glycoprotein to a resolution of 2 nm. The glycoprotein is arranged on a p6 lattice with a lattice constant of 16.8 nm. It forms 4.5 nm high, dome-shaped, morphological complexes with a narrow pore at the apex opening into a `funnel' towards the cell membrane. The polarity of the structure was derived from freeze-etching experiments and `edge' views. Six radial protrusions emanate from each morphological complex and join around the 3-fold axis to provide lateral connectivity. Using the primary structure of the surface glycoprotein of the closely related species Halobacterium halobium (Lechner and Sumper, 1987) and the cell envelope profile from a previous X-ray analysis of the same species (Blaurock et al., 1976) we have integrated our reconstruction into a model of halobacterial cell envelope.     

Gibbs free energy of transfer of glycine and diglycine from water to alkylurea solutions. Measured vs. calculated values

Ternary systems comprising water (1), glycine (diglycine) (2) and alkylurea (3) have been investigated using vapor pressure osmometry. Equations were obtained in terms of the molalities of the solutes for the activity coefficients of glycine and diglycine in these systems. The alkylureas used were methyl-, ethyl- and N, N'-dimethylurea. Using the activity coefficients the Gibbs free energy of transfer at infinite dilution of component 2 from water to alkylurea solutions was determined. Since the enthalpies of transfer are known, the corresponding entropies could also be obtained. Calculation of the Gibbs free energy of transfer at infinite dilution of component 2 rests on the assumption that it can be divided into two parts: the difference between the Gibbs free energy of cavity formation and that of interaction in the alkylurea solution and water, respectively. The first part was calculated by scaled particle theory using experimental density and surface tension data. The second part was taken to be due mainly to the change in dipole-dipole interactions.     

Resonance Raman spectra of chlorophylls dissolved in liquid crystal matrices. II. Order parameters of chlorophyll a in an MBBA + EBBA liquid crystalline mixture

The molecular ordering of molecules embedded in a uniaxial liquid crystalline system has been considered. In particular, planar Chl a molecules in an MBBA + EBBA mixture have been studied by using polarized resonance Raman spectroscopy. The second- and fourth-rank order parameters and the orientational distribution function of Chl a in the nematic MBBA + EBBA liquid crystalline phase are discussed.     

A new model of counterion condensation in polyelectrolyte solutions. III. Theoretical predictions of competitive condensation between counterions of different valences

Our model has been extended for theoretical estimation of competitive condensation of counterions of different valences onto polyelectrolytes in solution. The estimations are compared with those obtained from Manning theory and with experimental data on counterion activity coefficients. The agreement with the data for sodium polystyrenesulfonate/MgCl2, CaCl2 is satisfactory.     

介绍一种研究寄主-寄生昆虫关系的四臂气流式测定仪

许多膜翅目寄生性昆虫首先通过嗅觉反应趋向于寄主栖息地,然后再寻找寄主,为了研究这个过程,就需要一种嗅觉测定仪。过去采用的Y型或T型嗅觉测定仪,因为它们不能形成边界分明而毗连的气味区域而让天敌自由进出,此外,在Y型或T型管的三臂相交处会导致气味的混合,因而存在干扰效应。在这种情况下,小型寄生昆虫难以进行趋化性试验,通常由于行为上的诱导(例如强烈的趋光性反应),寄     

沟胸细条虎天牛的初步观察

沟胸细条虎天牛(华立中,1982年,《中国天牛科昆虫名录》上又称“沟胸克虎天牛”——编者)是近几年乌鲁木齐地区发现的一种为害林木果树的害虫;幼虫为害林木幼枝,而成虫大量吞食花粉;造成果树授粉率降低,减少座果和果品产品。在乌市一年发生一代;5月中旬开始出现成虫,5月下旬至6月中旬成虫大量飞出、交配并产卵,成虫经16天左右死亡。幼虫在树枝内钻蛀生活到10月下旬,蛹期9天左右即羽化为成虫,以成虫在枝条内越冬。     

黄星蝗生物学特性观察简报

<正> 黄星蝗Aularches miliaris scabiosus Fa-bricius分布于我国西南地区,四川仅分布于西昌、宁南、会理3县。我们通过室内饲养和野外观察,发现该虫在西昌地区每年发生一代,每世代历期214天。 在室内,4月上旬(2～8日)卵开始孵化,4月中下旬(15～27日)为盛孵期。在野外,4月中旬可见到蝻,蝻体色黑褐,腹部有黄色及红色斑点。初孵蝻活动范围极小,3天后其范围扩大,并出现群体迁移现象,寻找可取食的农作