褪黑素：一个多功能的光周期信号

褪黑素：一个多功能的光周期信号汪晓飞刘志民彭树勋（香港大学医学院生理学系,香港）目录一、褪黑素的分泌（一）正常情况（二）异常情况１．生殖系统异常２．睡眠异常３．精神紊乱二、褪黑素的作用（一）生殖系统（二）脂肪代谢和毛发替换（三）睡眠（四）免疫系统（五...     

从食肉类与食草类的形态比较话生物进化与体育竞技

科学进化论的创始者 ,法国博物学家拉马克( 174 4～ 182 9)在 180 9年发表的《动物学的哲学》一书中提出了物种可变 ,生物进化的学说。其中一个著名的法则便是“用进废退”。这一法则指出 ,凡是没有达到其发展极限的每一动物的任何器官 ,在环境条件的影响下 ,受到动物本身的意志、欲望等的作用经持续使用 ,便会逐渐增强这个器官 ,使它发达扩大起来。相反 ,任何器官若不经常使用 ,则会逐渐衰弱 ,功能减弱 ,以至最后消失。这一理论的最著名的例子便是长颈鹿。长颈鹿祖先的脖子并不是很长 ,但由于它们当时所处的生活环境中只有高树的叶子可以充…     

染色体结构变异的生物诱导--杀配子染色体的作用及其在生物进化上的意义

来自山羊草属的某些种的染色体在不同小麦背景下,具有不同强度的杀配子能力,从而可高频诱导各类染色体结构变异,与各类物理、化学手段相比,其作用特点具有高效性、多方向性及稳定性等,这种来自生物内部的诱导方式可称为生物诱导,在小麦与山羊草的进化上可能起着隔离基因的作用。     

褪黑素调控动物繁殖功能的作用途径

褪黑素是由松果体分泌的一种多功能吲哚类激素,在动物繁殖过程中起了至关重要的作用.褪黑素可通过多条途径调控动物的繁殖功能,主要包括：G蛋白偶联受体途径;作为神经内分泌激素对动物繁殖进行调控;与其核受体结合在转录水平上调控动物繁殖;通过抗氧化作用调控卵泡发育.本文就褪黑素对动物繁殖功能的调控途径进行综述,旨在为褪黑素调控动物繁殖的相关研究提供帮助.     

有氧运动和褪黑素对2型糖尿病大鼠抗氧化运动功能的影响

目的：探讨有氧运动和褪黑素对糖尿病大鼠抗氧化功能的影响。方法：成年sD大鼠50只随机分为5组（n=10）：正常对照组（N）、糖尿病组（D）、糖尿病运动组（D＋E）、糖尿病褪黑素组（D＋M）、糖尿病运动和褪黑素组（D＋E＋M）,观察大鼠血清丙二醛（MDA）、超氧化物歧化酶（SOD）、谷胱甘肽过氧化物酶（GSH．Px）、血糖和血脂的变化。结果：与N组相比,D组大鼠血清SOD、cSH-PX水平、高密度脂蛋白胆固醇（HDL-C）含量下降,MDA水平、血糖、胆固醇（TC）、血清甘油三酯（TG）和低密度脂蛋白胆固醇（LDL-C）含量明显上升（P〈0．05,P〈0．01）。D＋E组和D＋M组大鼠与D组比较血清中SOD、GSH-Px活性、HDL-C含量显著升高,MDA水平、血糖、TC、TG和LDL-C含量显著降低（P〈0．05,P〈0．01）,有氧运动和褪黑素同时干预可使糖尿病大鼠血清中SOD、GSH-Px活性、HDL-C含量进一步升高,MDA水平、血糖、TC、TG和LDL-C含量进一步降低（P〈0．05,P〈0．01）。结论：有氧运动扣褪黑素均能对糖尿病大鼠氧化应激有明显的抑制作用,且两者联合干预的效果更加显著,其可能机制与糖尿病大鼠的糖脂代谢紊乱状态改善有关。     

生命起源的历程始于何处?--从化学进化到生物进化的探索

生命起源开始于从化学进化进入生物进化．然而,在原始细胞出现之前,已存在一个有蛋白质、核酸等生命要素的过渡期．那么,生命起源的历程究竞从何处开始?对这个未解之迹,进行了讨论．首先,从化学进化到生物进化要实现3个相变,即：从随机的有机化学反应相变为定向代谢途径;从消旋体环境相变为生物手性环境：从化学混沌状态相变为生命耗散结构．通过比较分析发现,由于前生命化学时期出现了丙酮酸．它的独特性质导致了这3种相变同步发生,其中起驱动作用的是定向代谢途径．它起源于以丙酮酸为基质的逆向糖酵解(糖生成途径)．     

褪黑素在哺乳动物皮肤中的生物学功能及对山羊绒生长的调控作用

褪黑素(melatonin, MT)可促进山羊绒的生长,提高山羊绒的产量,增加养羊业的经济效益。本文阐述了哺乳动物皮肤中褪黑素的生物合成、代谢和功能,对褪黑素调控山羊绒生长的国内外研究进展进行了综述,对未来研究方向进行了展望,以期为绒山羊研究人员深入探索褪黑素促山羊绒生长的机理提供参考。     

褪黑素调节烟草丁香假单胞菌抗性的功能研究

为分析褪黑素(N-乙酰-5-甲氧基色胺)在植物先天免疫中的功能及调控机理,研究以病原菌丁香假单胞杆菌(Pseudomonas syringae pv.tomato DC3000,Pst DC3000)—烟草互作系统为模型,检测了病原菌侵染对烟草褪黑素相关基因表达的影响,并探讨了褪黑素对植物叶片病原菌生长以及气孔开度和活性氧自由基(reactive oxygen species,ROS)含量的影响以及调控机理。结果表明:(1)Pst DC3000处理提高了烟草褪黑素合成(NtSNAT1)和受体(NtPMTR1)基因表达,且外源褪黑素处理降低了叶片中的病原菌含量。(2)与野生型植物相比,过表达大豆GmSNAT1基因显著提高了转基因烟草中内源褪黑素含量和NtPMTR1的表达,且转基因烟草叶片中的Pst DC3000菌落数显著下降。(3)外源褪黑素和细菌鞭毛蛋白多肽flg22处理诱导了野生型和转基因烟草保卫细胞中ROS产生和气孔关闭,且转基因植物对褪黑素和flg22诱导的气孔关闭和ROS产生比野生型烟草更加敏感。综上所述,研究表明褪黑素可能通过受体NtPMTR1介导的信号途径促进保卫细胞ROS产生,诱导气孔关闭,从而降低病原菌Pst DC3000的入侵。     

褪黑素对大鼠内毒素性肺损伤抗氧化功能及ICAM-1表达的影响

目的:探讨褪黑素(MT)对大鼠急性肺损伤(ALI)时肺脏的保护作用及其可能机制。方法:将大鼠随机分为4组:对照组;脂多糖(LPS)组;地塞米松(DEX)和MT处理组。各组动物分别于气道内滴注后3、6和12h检测肺组织髓过氧化物酶(MPO)和超氧化物歧化酶(SOD)活性及丙二醛(MDA)含量;免疫组化检测细胞间黏附分子-1(ICAM-1)在肺组织的表达。结果:LPS组SOD活性较对照组明显降低(P<0.01),而MPO活性与MDA含量以及ICAM-1的表达则显著升高(P<0.01);应用MT及DEX均显著缓解上述变化(P<0.05或P<0.01)。结论:MT对ALI时的肺脏起明显的保护作用,其机制可能与MT清除自由基及抑制ICAM-1的表达有关。     

褪黑素对顺铂的听觉中枢毒性的影响

目的：研究顺铂的中枢听觉毒性以及褪黑素对其的保护作用。方法：用顺铂和不同浓度褪黑素分别在豚鼠左右腹腔注射7d后,用分光光度计测量听皮层脑组织LDH活力、MDA、NO含量。结果：顺铂注射7d后各组的体重均下降,其中以单独注射顺铂组和10mg·kg^-1·d^-1褪黑素加顺铂组下降趋势最明显,较处理前有显著差异（P〈0．01）。顺铂组动物听皮层LDH活力水平明显高于生理盐水组（P〈0．01）;褪黑索能显著降低顺铂引起的听皮层脑组织中的LDH增高（P〈0．05）。豚鼠腹腔注射顺铂7d后听皮层MDA含量较腹腔注射生理盐水组明显增高（P〈0．01）;同时腹腔注射褪黑素能降低听皮层组织MDA含量（P〈0．05）。各药物作用后听皮层的NO含量变化统计学比较无显著性意义。结论：腹腔注射顺铂能够作用于听皮层引起细胞损伤。褪黑素对顺铂所致的听皮层细胞损伤有防护作用,机制可能与其抗自由基作用有关。     

The changing biological roles of melatonin during evolution: from an antioxidant to signals of darkness,sexual selection and fitness

Melatonin is a molecule present in a multitude of taxa and may be ubiquitous in organisms. It has been found in bacteria, unicellular eukaryotes, macroalgae, fungi, plants and animals. A primary biological function of melatonin in primitive unicellular organisms is in antioxidant defence to protect against toxic free radical damage. During evolution, melatonin has been adopted by multicellular organisms to perform many other biological functions. These functions likely include the chemical expression of darkness in vertebrates, environmental tolerance in fungi and plants, sexual signaling in birds and fish, seasonal reproductive regulation in photoperiodic mammals, and immunomodulation and anti‐inflammatory activity in all vertebrates tested. Moreover, its waning production during aging may indicate senescence in terms of a bio‐clock in many organisms. Conversely, high melatonin levels can serve as a signal of vitality and health. The multiple biological functions of melatonin can partially be attributed to its unconventional metabolism which is comprised of multi‐enzymatic, pseudo‐enzymatic and non‐enzymatic pathways. As a result, several bioactive metabolites of melatonin are formed during its metabolism and some of the presumed biological functions of melatonin reported to date may, in fact, be mediated by these metabolites. The changing biological roles of melatonin seem to have evolved from its primary function as an antioxidant.     

Induction of lipid peroxidation in hamster organs by the carcinogen cadmium: melioration by melatonin

Cadmium is a well-known human carcinogen. Lipid peroxidation is involved in cadmium-related toxicity and carcinogenesis. Melatonin is an effective antioxidant and free radical scavenger. The potential protective effects of melatonin against cadmium-induced lipid peroxidation in hamster brain, heart, kidney, testes, lung, and liver were examined. Lipid peroxidation was induced by intraperitoneal injection of cadmium chloride [single dose of 1 mg/kg body weight (bw)]. To test whether melatonin would protect against the toxicity of the carcinogen, the melatonin was injected peritoneally at a dose of either 15 mg/kg bw or 5 mg/kg bw, 0.5 h before cadmium treatment and thereafter at 8 h intervals during the day in the 48 h interval following the cadmium injection. One group of hamsters received only a single melatonin injection (a dose of 15 mg/kg bw, 30 min prior to cadmium). Forty-eight hours after cadmium injection, lipid peroxidation increased in brain, heart, kidney, testes, and lung. Either multiple injections of melatonin at both the 5 and 15 mg/kg bw doses, or a single injection of 15 mg/kg bw, prevented the cadmium-related increases in lipid peroxidation in brain, heart and lung. Cadmium-induced lipid peroxidation in kidney was prevented by melatonin when it was given as a single dose of 15 mg/kg bw. Melatonin slightly, but not significantly, reduced cadmium-induced lipid peroxidation in testes. It is concluded that cadmium toxicity, at least with regard to the resulting lipid peroxidation, is reduced by administering melatonin. This revised version was published online in July 2006 with corrections to the Cover Date.     

The effect of melatonin on free radical homeostasis in rat tissues at thyrotoxicosis

Experimental thyrotoxicosis in rats is accompanied by the increase of serum alanine aminotransferase (AlAT), aspartate aminotransferase (AsAT), creatine phosphokinase-MB (CPK-MB) activities and the content of primary products of lipid peroxidation, conjugated dienes, in liver, heart and blood. This suggests impairments in functioning of these organs, which accompany intensification of free radical processes. Melatonin administration resulted in the decrease of AlAT, AsAT, CPK-MB and conjugated dienes; this indicates positive effect of melatonin in this pathology. Thyrotoxicosis is accompanied by the increase of catalase activity in rat liver, heart and serum. Exogenous melatonin decreased specific activity of serum and heart catalase by 22 and 43%, respectively, compared with rats subjected to hyperthyroidism. However, there was insignificant increase in specific activity of liver catalase (by ～15%). Melatonin administration caused a decrease of α-tocopherol content increased in rat tissues under conditions of hyperthyroidism. Thus, exogenous melatonin is capable to reduce intensity of lipid peroxidation in hyperthyroidism and to act as an adaptogen, regulating free radical homeostasis in response to action of pathogenic factors on organism that is associated by concomitant reduction of mobilization of components of the antioxidant system.     

褪黑素及其在昆虫学研究中的展望

褪黑素是一种与光周期相关的内源激素。它在生物界分布广泛,并在复杂而漫长的生物进化过程中作为一种多功能分子保留至今。褪黑素在生物体内起着调节时间节律、免疫和抗氧化等作用,从而可使生物机体保持内环境稳定,更好地适应环境。开展昆虫褪黑素与昆虫行为发育关系的研究,尤其是分子生物学方面的研究,对进一步揭示褪黑素的生理功能具有重要的意义。作者根据近年来的相关研究及进展进行了综述。     

褪黑激素的研究进展

褪黑激素是一种在多个物种的多个组织中广泛存在并具有重要生理作用的激素。本文拟就褪黑激素在体内的分布,褪黑激素受体的分子结构、药理学特性、生物功能及调控模式作一简述。     

The protective effect of melatonin against cypermethrin-induced oxidative stress damage in Spodoptera litura (Lepidoptera: Noctuidae)

Antioxidant enzymes form the first-line defense against free radicals damage in organisms. Their regulation depends mainly on the oxidant and antioxidant status of the cell, given that oxidants are their principal modulators. Therefore, the aim of the present study was to investigate the effect of melatonin on synthetic pyrethroid insecticide-induced antioxidative enzymes activity in Spodoptera litura larvae. In addition, activities of enzymatic antioxidants viz. superoxide dismutase (SOD), glutathione S-transferase (GST), catalase (CAT), glutathione reductase (GR), α, β-esterase, and acetylcholine esterase (AChE) were assessed. There was no significant change in GST levels in the melatonin-treated groups. Melatonin modulates cypermethrin-induced changes in the activities of esterase and AChE, whereas SOD, CAT, and GR activity was significantly increased in melatonin-treated samples when compared to control. In conclusion, the results of the current study revealed that SP toxicity activated oxidant systems in all antioxidant systems in some tissues of insects. Melatonin administration led to a marked increase in antioxidant activity and inhibited GST and AChE in most of the tissues studied.     

Molecular evolution of the ankyrin gene family

Ankyrins are membrane adaptor molecules that play important roles in coupling integral membrane proteins to the spectrin-based cytoskeleton network. Human mutations of ankyrin genes lead to severe genetic diseases such as fatal cardiac arrhythmias and hereditary spherocytosis. To elucidate the evolutionary history of ankyrins, we have identified novel ankyrin sequences in insect, fish, frog, chicken, dog, and chimpanzee genomes and explored the phylogenetic relationships of the ankyrin gene family. Our data demonstrate that duplication of ankyrin genes occurred at two different stages. The first duplication resulted from an independent evolution event specific in Arthropoda after its divergence from Chordata. Following the separation from Urochordata, expansion of ankyrins in vertebrates involved ancestral genome duplications. We did not find evidence of coordinated arrangements of gene families of ankyrin-associated membrane proteins on paralogous chromosomes. In addition, evolution of the 24 ANK-repeats strikingly correlated with the exon boundary sites of ankyrin genes, which might have occurred before its duplication in vertebrates. Such correlation is speculated to bring functional diversity and complexity. Moreover, based on the phylogenetic analysis of the ANK-repeat domain, we put forward a novel model for the putative primordial ankyrin that contains the fourth six-ANK-repeat subdomain and the spectrin-binding domain. These findings will provide guides for future studies concerning structure, function, evolutionary origins of ankyrins, and possibly other cytoskeletal proteins.