Polymerization of the Tryptophanyl tRNA Synthetase Complex with Tryptophan

To understand the mechanism of mutual recognition between aminoacyl tRNA synthetases (EC 6.1.1) and tRNAs, it is important to obtain more information about the structure of these enzymes. X-ray crystallography offers one approach, but although several aminoacyl tRNA synthetases have been isolated in very pure form¹ and crystallization of tryptophanyl² and seryl³ tRNA synthetases has been reported, no crystals were available that were suitable for structural analysis. Only very recently have Rymo and Lagerkvist⁴ described the formation of crystals of yeast lysyl tRNA synthetase which are apparently suitable for further X-ray analysis. Here we deal with the phenomenon of polymerization of the tryptophanyl tRNA synthetase complex with tryptophan in the form of rod-like particles and the subsequent formation of para-crystalline aggregates.     

Phenotypic and genotypic structure of a natural Drosophila population for meristic morphologic characters and its seasonal changes

A natural population of Drosophila was genetically heterogeneous in the number of sternopleural bristles and the number of arista branches. In the summer, these characters had a low mean value and high coefficient of variation: in autumn, this relationship was reversed; in late spring, the values of the mean and coefficient of variation were intermediate. The dynamics of the character mean was determined by changes in phenotypic and genotypic composition of the population, which was examined during different seasons of the year. On average, the number of sternopleural bristles was higher, and the number of arista branches was lower in females than in males. The number of sternopleural bristles exhibited a higher phenotypic and genotypic variation than the number of arista branches.     

Cold related mortalities and protection against cold in Yakutsk,eastern Siberia: observation and interview study

Objective To assess how effectively measures adopted in extreme cold in Yakutsk control winter mortality.Design Interviews to assess outdoor clothing and measure indoor temperatures; regressions of these and of delayed cause-specific mortalities on temperature.Setting Yakutsk, east Siberia, Russia.Subjects: All people aged 50-59 and 65-74 years living within 400 km of Yakutsk during 1989-95 and sample of 1002 men and women who agreed to be interviewed.Main outcome measures Daily mortality from all causes and from ischaemic heart, cerebrovascular, and respiratory disease.Results Mean temperature for October-March 1989-95 was −26.6°C. At 10.2°C people wore 3.30 (95% confidence interval 3.08 to 3.53) layers of clothing outdoors, increasing to 4.39 (4.13 to 4.66; P<0.0001) layers at −20°C. Thick coats, often of fur, replaced anoraks as temperature fell to −48.2°C. 82% of people went out each day when temperatures were 10.2°C to −20°C, but below −20°C the proportion fell steadily to 44% (35% to 53%) at −48.2°C (P<0.001), and overall shivering outdoors did not increase. Living room temperature was 17.9 (17.2 to 18.5)°C at 10.2°C outdoors, 19.6 (18.8 to 20.4)°C at −20°C, and 19.1 (18.6 to 19.6)°C at −48.2°C. Mortality from all causes and from ischaemic heart and respiratory disease was unaffected by the fall in temperature. Mortality from respiratory disease (daily deaths per million) rose from 4.7 (4.3 to 5.1) to 5.1 (4.4 to 5.7) (P=0.03), but this was offset by a fall in deaths from injury.Conclusions People in Yakutsk wore very warm clothing, and in extremely cold weather stayed indoors in warm housing, preventing the increases in mortality seen in winter in milder regions of the world. Only respiratory mortality rose, perhaps because of breathing cold air.

Key messages

• Death rates from ischaemic heart, cerebrovascular, and respiratory disease and all causes have been shown to increase as air temperature falls
• In Yakutsk, Russia, mortality from cerebrovascular and ischaemic heart disease and all causes among people aged 50-59 and 65-74 was unchanged as temperature fell to −48.2°C
• Mortality from respiratory disease increased as temperatures fell below −20°C but this was more than offset by a decrease in deaths from accidents
• Exceptionally warm clothing, with reduction of outdoor excursions at temperatures below −20°C, prevented overall outdoor cold stress

     

以HSV-1扩增子载体构建的新型重组AAV载体包装系统

将缺失两端ITR的AAV -2基因组克隆于HSV -1扩增子载体获得了质粒pHSV AAV .以HSV- 1tsK株为辅助病毒感染转染了该质粒的Vero细胞 ,可获得一种具有包装重组AAV质粒能力的混合毒种 .连续传代可使其包装能力迅速升高 ,至 5～ 6代达到最高并趋于平稳 .此混合毒种中 ,含有包装了多拷贝AAV -2基因组的复制缺陷性假型HSV- 1病毒 ,它可表达AAV -2编码的复制与包装所需的各种反式蛋白 ;同时也含有HSV -1tsK病毒 ,它提供AAV -2复制与包装所需的全部辅助病毒功能 .实验结果也表明 ,HSV -1tsK病毒的复制为混合毒种辅助重组AAV载体的包装所必需 .这项研究首次报道了一种全新的重组AAV载体包装系统 ,与传统的双质粒共转染、腺病毒辅助包装方案相比 ,本系统简便易行 ,并明显提高了重组AAV的包装效率 .     

Molecular characterization and functional expression of opioid receptor-libe_1 receptor

INTRODUCTIONOpioidactsinthecentralandperipheralnervoussystem(CNSandPNS)to'producenumerouspharmacologicaleffects.Repetitiveorcontinuoususeofopioids,however,causesdrugtoleranceanddependence.Threesubtypesofopioidreceptors,termedp)6,andK,havebeencloned.TheyarecoupledtotheinhibitoryGproteinandnegativelyregulateadenylylcyclasell].RecentlyanewG-proteincoupledreceptortermedopioidreceptor-likereceptor(ORLI)whichbelongstothenewlycharacterizedopioidreceptorsubfamilyhadbeenclonedfromhumanbrainst…     

The Effect of Concanavalin A on Membrane Potential and Intracellular pH during Activation In Vitro of Tobacco Pollen Grains

We studied the effects of short-term (5–10 min) treatment of Nicotiana tabacum L. pollen grains with concanavalin A (ConA) on their activation (changes in the membrane potential and intracellular pH) and germination in vitro. ConA (10–1000 g/ml) induced plasma membrane hyperpolarization in the vegetative cell and enhanced pollen grain germination. These effects depended on ConA concentration and were interrelated: the value of the membrane potential was negatively correlated with the number of pollen grains germinated for 1 h of their incubation (r = –0.96). In addition, ConA (100 g/ml) increased the intracellular pH value by 0.3 unit. All these effects of ConA are determined by its specific interaction with carbohydrate determinants because a competitive sugar methyl--mannopyranoside (0.1 M) completely blocked ConA effects. The data obtained presume that the specific receptors are present on the surface of pollen grains, evidently on their plasma membrane, and their interaction with lectins has a functional significance for pollen grain activation and germination.     

Effect of weak combined magnetic fields on the metamorphosis of the meal-worm beetle Tenebrio molitor

The effects of weak combined magnetic fields adjusted to the parametric resonance for Ca2+ and K+ and extremely weak alternating magnetic field on the metamorphosis of the meal-worm beetle Tenebrio molitor have been studied. It was shown that the exposure of pupas of insects to all above-indicated types of fields stimulates the metamorphosis. However, after the exposure to weak combined magnetic fields adjusted to the parametric resonance for Ca2+ and K+, the number of insects with anomalies increases, which is not observed by the action of the weak alternating magnetic field.     

PERFORMANCE,CARCASS CHARACTERISTICS,MEAT QUALITY AND PLASMA CONSTITUENTS OF MEAT TYPE DRAKES FED DIETS CONTAINING DIFFERENT LEVELS OF LYSINE WITH OR WITHOUT A MICROBIAL PHYTASE

This experiment was conducted to study growth performance, carcass characteristics, meat quality and plasma constituents of Campbell drakes fed diets containing different levels of lysine with or without a microbial phytase. Basal vegetable duck all-mash diets were fed during the growing (1- 35 d of age), and finishing period (36 - 56 d of age) and were formulated to contain 0.90% and 0.73% lysine (negative control), respectively. These diets were supplemented or not with L-lysine HCl, which resulted in a dietary lysine level of 0.90, 0.95, 1.01 and 1.06% and 0.73, 0.80, 0.87 and 0.94%, during the growing and finishing period, respectively. Furthermore, the diets were fed with or without 600 FTU phytase (Natuphos®) except for those containing 1.06 and 0.94% lysine during the growing and finishing period, respectively (positive control). A lysine level of 1.01/0.87% in the growing/finishing diet significantly increased BWG and improved FCR of drakes by 2.1 and 1.8%, respectively. Phytase significantly increased BWG by 2.1% and 3.5% after feeding the basal diet and 1.01/0.87% lysine, respectively. Also, FCR was significantly improved by 2.2 and 1.8% of groups fed 0.95/0.80, and 1.01/0.87% lysine, respectively. Phytase as an independent variable increased BWG by 1.8, and improved FCR by 1.0%. Lysine and/or phytase did not affect carcass yield, and meat quality treats as well as plasma constituents of drakes. However, lysine level at 0.95/0.80% and 1.01/0.87% significantly decreased abdominal fat deposition compared to either the negative or the positive control. In conclusion, a lysine level of 1.01/0.87% in the growing/finishing diets for drakes is adequate. After phytase supplementation of the basal diet the BWG at a lysine level of 0.90/0.73% were similar to the positive control (1.06/0.94% lysine). However, the best FCR was obtained after feeding diets containing 1.01/0.87% lysine supplemented with phytase.     

Paticipation of cannabinoid receptors in the regulation of cardiac rhythm and cardiac contractility

It has been found that i. v. administration of cannabinoid receptor (CB) agonists (HU-210, ACPA, anandamide, methanandamide) induced a decrease in the heart rate (HR) in anesthetized rats. Pretreatment with CB1 receptor antagonist SR141716A completely abolished a negative chronotropic effect of CB receptor agonist HU-210. The CB2 receptor antagonist SRI 44528 did not prevent a HU-210-induced decrease in the HR. Pretreatment with the ganglion blocker hexamethonium had no effect on the negative chronotropic action of HU-210. Addition of HU-210 (100 nM) to perfusion solution induced a decrease in the HR, left ventricular development pressure, rate of contractility and relaxation of isolated perfused rate heart without change in end diastolic pressure. These data suggest that cardiac CBI receptor activation induces a decrease in the HR both in vivo and in vitro. An occupancy of the same receptors mediates a negative inotropic effects of cannabinoids.     

涠洲岛海域球形棕囊藻藻华过程中营养盐及浮游植物群落组成分析

球形棕囊藻(Phaeocystis globosa)是近年来北部湾常见的有害藻华原因种,涠洲岛海域作为广西沿海藻华的高发区之一,目前仍缺乏关于该海域球形棕囊藻藻华过程的相关研究。为探究涠洲岛海域球形棕囊藻藻华过程中营养盐的状况及藻华的发生对浮游植物群落组成的影响,对2017年3月下旬涠洲岛周边发生的球形棕囊藻藻华区域进行取样调查。结果表明,藻华期间水体中溶解有机磷含量与细胞及囊体密度呈显著正相关。本次藻华主要受水体中溶解态无机氮含量影响,多个调查站点的无机氮/无机磷(DIN/DIP)<10,且硅酸盐/无机氮(SiO₃^2–/DIN)>1,表明这些站点存在氮限制现象,而氮限制可能是本次藻华消亡的主要因素。调查区域共鉴定出浮游植物4门58种,球形棕囊藻细胞密度最高可达1.04×10⁸ cells/L,占浮游植物总细胞密度的98.28%。球形棕囊藻细胞密度与物种多样性指数存在显著的负相关关系。在营养缺乏条件下,有利于球形棕囊藻成囊的链状硅藻种类具有相对较大的细胞密度。