Differential rescue of light- and food-entrainable circadian rhythms

When food is plentiful, circadian rhythms of animals are powerfully entrained by the light-dark cycle. However, if animals have access to food only during their normal sleep cycle, they will shift most of their circadian rhythms to match the food availability. We studied the basis for entrainment of circadian rhythms by food and light in mice with targeted disruption of the clock gene Bmal1, which lack circadian rhythmicity. Injection of a viral vector containing the Bmal1 gene into the suprachiasmatic nuclei of the hypothalamus restored light-entrainable, but not food-entrainable, circadian rhythms. In contrast, restoration of the Bmal1 gene only in the dorsomedial hypothalamic nucleus restored the ability of animals to entrain to food but not to light. These results demonstrate that the dorsomedial hypothalamus contains a Bmal1-based oscillator that can drive food entrainment of circadian rhythms.     

Phototaxis and sensory transduction in Euglena

The accumulation of Euglena gracilis in an illuminated region is brought about by two main mechanisms: orientation and subsequent directed movement (positive phototaxis) toward light scattered from particles in the illuminated zone; and by the trapping of cells in this region because of shock reactions experienced upon the cells encountering a sudden decrease of light intensity at the light-dark boundary (inverse photophobic responses).Phototactic orientation is mediated by inverse photophobic reactions which occur when the shadow of the stigma periodically falls upon the photoreceptor proper. Euglena also exhibits shock reactions when an already high light intensity is increased further (direct photophobic responses). The expression of both types of phobic responses depends upon stimulus intensity and adaptation of the sensory system in a seemingly complex way. A definition of the minimum components of the stimulus transduction system and a systems analytical approach to the study of input-output relationships enables one to construct an electronic analog of the cell's signal processing system that converts the photoreceptor input to commands which activate or inhibit flagellar reorientation. Computer simulation studies show that this model has considerable predictive value. It is hoped that with the approach presented in this article, a generalized model has become available for dealing with the questions of sensory transduction in aneural systems. Certainly, at this point more questions have been raised than have been answered. Where is the processing device located? Are its kinetic properties determined by electrical processes or by the rates of chemical reactions? Is the processor, and thereby the behavior of the orgamism, modulated by natural environmental parameters, and can it be modified permanently through more drastic chemical treatment of the cell? Is the system capable of permanent or transitory modification through repeated response, that is, does it exhibit phenomena analogous to learning and memory in higher organisms? These are only a few of the problems that require study in the future.     

Symbiosis between Euglena and damselfly nymphs is seasonal

An endosymbiotic association has been demonstrated between Euglena and nymphs of three species of damselfly. The hindgut of the nymphs is inhabited by the euglenoid only during the winter. Symbiotic associations involving green euglenoids and insects are virtually unknown.     

Comment on "Differential rescue of light- and food-entrainable circadian rhythms"

Fuller et al. (Reports, 23 May 2008, p. 1074) reported that the dorsomedial hypothalamus contains a Bmal1-based oscillator that can drive food-entrained circadian rhythms. We report that mice bearing a null mutation of Bmal1 exhibit normal food-anticipatory circadian rhythms. Lack of food anticipation in Bmal1-/- mice reported by Fuller et al. may reflect morbidity due to weight loss, thus raising questions about their conclusions.     

Phagocytosis of light- and dark-adapted rod outer segments by cultured pigment epithelium

Pigment epithelial cells in culture retain their ability to phagocytize rod outer segments. These cells phagocytize rod outer segments isolated from light-adapted rats, or from dark-adapted rats killed after the time at which the lights would normally be turned on. However, they phagocytize for fewer rod outer segments prepared in the dark from the retinas of rats killed before the onset of the normal light cycle. Phagocytosis of dark rod outer segments is variable, but that of light outer segments is reproducible. It is postulated that the effect of light is to synchronize the chemical events that occur at the surface of the rods to prepare them for phagocytosis. These processes also occur in the dark, but more slowly and irregularly than in the light.     

越南植物分布新记录

报道了越南2种植物分布新记录,包括夹竹桃科Apocynaceae的保亭鳝藤Anodendron howii Tsiang和大戟科Euphorbiaceae的枝翅珠子木Phyllanthodendron dunniarmm Levl.     

腐烂柑橘中两株细菌的分离与鉴定

以腐烂的柑橘为材料,分离纯化得到两株致病的细菌。根据菌株的形态特征并结合16SrDNA序列比对分析,确定两株细菌分别属于芽孢杆菌属(Bacillus)和短芽孢杆菌属(Brevibacillus)。与此同时对两株细菌的生长曲线、抗生素抗性进行测定,以期为柑橘由细菌导致的病害的防治提供理论基础。     

从两篇文章中透析企业文化

因为从事企业文化工作的缘故,笔者读过很多关于企业文化的文章,其中有两篇经典之作,对企业文化的理解有非常深刻的内涵,一篇是TCL集团董事长李东生写的《鹰的重生》,一篇是华为集团董事长任正菲写的《华为的冬天》.     

神农架蕨类植物二新种

报道了湖北神农架蕨类植物２新种－神农岩蕨和新正宇耳蕨。神逐岩蕨仅见于神农架海拔２８６０ｍ的巴东垭,与蜘蛛岩蕨相近,区别在于前者植物体较小,叶柄和叶轴黑色,下部羽片几不变小。新正宇耳蕨见于神农架海拔１６００ｍ的千家坪,少见分布,接近正宇耳蕨但新正宇耳蕨叶片线形,薄革质,小羽片多达２６对,密接,下部的几不反折,可以区别。     

广东省2种新记录植物

报道了新近发现的2种广东省新记录植物,泡果苘Abutilon crispa（Linn．）Medicus和疏花鸡屎藤Paeder／alaxorlora Merr．ex Li。标本存放于华南农业大学林学院植物标本室（CANT）。     

柑桔蚧虫的两种重要寄生蜂

 本文详细记述了柑桔蚧虫的2种重要的寄生蜂:蜡蚧刷盾短缘跳小蜂Encyrtuslecaniorum(Mayr),中国新记录,和柑桔粉蚧广腹细蜂Allotropa citri Muesebeck。它们分别寄生于褐软蚧和柑桔粉蚧,寄生率甚高。     

2株鸭源肠球菌的生物学特性的观察

对2株鸭源肠球菌临床分离株和1株粪肠球菌参考菌株的形态特征、培养特性、生理生化特性、对药物的敏感性等生物学特性进行了初步研究。结果表明,3个被检菌株在光学显微镜下呈球形、革兰氏阳性染色和链状排列方式,能在10℃、45℃和6.5%NaCl肉汤等条件下生长,能耐热60℃30min,其特性均符合肠球菌属的特征,各菌株生化反应特性均与粪肠球菌特性基本一致,3个菌株均可鉴定为粪肠球菌。药敏试验结果表明,3个菌株均对青霉素、万古霉素、庆大霉素、红霉素和氯霉素敏感而对四环素耐药。     

两种香兰素腙类化合物的合成及抑菌活性初步研究

以香兰素为原料,与苯肼和对硝基苯肼缩合得到两种香兰素腙类化合物,其结构经1H-NMR、IR表征.初步的抑菌试验表明,这些化合物对大肠杆菌(Escherichia coli)和金黄色葡萄球菌(Staphylococcus aureus)具有一定的抑菌效果.     

Euglena gracilis: a novel lipid energy reserve and arachidonic acid enrichment during fasting

In Euglena gracilis grown in the dark, was esters, consisting of a combination of medium-chain fatty acids and alcohols that contain both odd and even numbers of carbon atoms, appear to be a reservoir for metabolic energy. When the organisms are fasted, their pellicular membrane systems become quite rich in long-chain polyenoic acids, mostly of the arachidonic acid family.     

重庆市棘影熊虫属两个新记录种记述

记述了重庆市棘影熊虫属两个缓步动物新记录种,即：加拿大棘影熊虫（异缓步纲,棘影科）和文氏棘影熊虫（异缓步纲,棘影科）。     

矛线总科线虫2个新纪录种

作者在2014年采集到的青岛市牡丹花根际土壤中,分离鉴定出2个线虫中国新纪录种,分别是大盘唇线虫Discalaimus major Andrássy,2002和菲利亚前矛线线虫Prodorylaimus iliarum Andrássy,1992.其中,大盘唇线虫的鉴别特征是体型较大,齿针较长,开口占据齿针长度的一半左右.唇区吸盘状、宽大,宽度约为33～37 μm.尾短,呈圆锥形.菲利亚前矛线线虫的鉴别特征是虫体细长,唇区轻微缢缩,齿针相对较短,约为16～20 μm.前直肠是肛门处体宽的3～4倍.尾呈线状,长度为310～380 μm,是肛门处体宽的12～15倍.     

桑螵蛸的抗氧化活性成分研究

[目的]研究桑螵蛸活性成分在体外试验中抗动脉硬化的效果。[方法]利用硫代巴比妥酸法、apoB-100裂解法和共轭双烯法测定桑螵蛸的抗动脉硬化活性。[结果]从桑螵蛸药材中分离到2种N-(3,4-二羟基苯基乙基)乙酰胺(化合物1)和2,4-二丁基苯甲醇(化合物2),化合物1和2在TBARS试验中表现出低密度脂蛋白的抗氧化活性,IC50值分别为5.7和9.1μmol/L。在apoB-100的裂解试验,共轭双烯的生成都表现出抗动脉硬化活性。[结论]桑螵蛸成分具有较强的抗动脉硬化活性。     

2种微藻总RNA提取方法的比较

以微茫藻和莱茵衣藻为材料,比较Trizol试剂法和SDS-LiCl沉淀法提取2种微藻总RNA的效果,以期筛选出适合微藻RNA的提取方法。结果表明,SDS-LiCl沉淀法能从微茫藻中提取高质量的RNA,而Trizol法和SDS-LiCl沉淀法均能从莱茵衣藻中获得高质量的RNA,但Trizol法更为简单有效。RT-PCR结果表明,SDS-LiCl沉淀法提取的微茫藻总RNA和Trizol法提取的莱茵衣藻总RNA都能直接用于分子克隆和基因表达分析等分子生物学实验。     

安徽省缓步动物两新纪录种记述

记述了安徽省缓步动物两新纪录种,分别是：Macrobiotus adelges Dastych,1977和Macrobiotus richtersi Murray1911,此两种均属于真缓步纲（Eutardigrada）并爪目（Parachela）大生科（Macrobiotidae）大生属（Macrobiotus）,在安徽省属首次发现。