粗糙脉孢菌驱动蛋白-1在菌丝极性生长中的功能

为了研究驱动蛋白-1的基因(Kin-1)在菌丝极性生长中的功能,本文以粗糙脉孢菌(Neurospora crassa)菌株为材料,利用同源重组技术尝试获得其敲除突变菌株Kin-1KO,并分析菌株87-3、Ku70RIP和Kin-1KO的菌丝生长情况.结果表明,与菌株87-3和Ku70RIP相比,菌株Kin-1KO的菌落...     

用限制酶消化法检测脉孢菌中ung-1基因的突变效应

用限制酶消化法检测脉孢菌中ung-1基因的突变效应.以粗糙脉孢菌Ku70为参照,通过NaNO2胁迫处理,经DNA提取,限制酶消化,检测ung-1基因的缺失效应.实验结果表明,ung-1突变体和Ku70的限制酶图谱存在差异,说明ung-1的缺失增加了DNA随机突变率;NaNO2的胁迫加剧了这一效应.     

几种丝状真菌原生质体的形成与再生

本文用商品混合酶酶解的方法,研究了黑曲霉、绿色木霉、桔青霉头孢霉、粗糙脉孢霉、紫色红曲霉、白地霉、凤尾菇、冬菇、平菇等10种13株丝状真菌原生质体的制备及再生,对这些真菌原生质体形成和再生过程中的形态学变化进行了观察,并通过透射电子显微镜的观察证明所得到的制备物确实为没有细胞壁的原生质体.实验表明,用商品纤维素酶、蜗牛酶、溶菌酶等配制成的混合酶液,可成功地从上述分属于子囊菌纲、担子菌纲、半知菌纲的丝状真菌菌丝体制备出原生质体.实验还说明,巯基乙醇对多数丝状真菌原生质体的形成并不是必需的.在所有供试菌株中均观察到由原生质体直接长出菌丝及由原生质体先形成酵母芽链状再长出菌丝这两类再生方式.     

球孢白僵菌几丁质酶的定位研究

采用酶解球孢白僵菌菌丝细胞壁以获得原生质体,用超声破碎器破碎细胞,并用差速离心等方法,对此丝状病原真菌细胞中几丁质酶的定位进行了研究.采用球孢白僵菌 Eu-120株,分别用几丁质酶、蜗牛酶和纤维素酶,以不同比例混合进行脱壁处理.通过测定培养物上清液及原生质体溶解物的几丁质酶活性,发现此培养物上清液中的酶活性占其总酶活性的81.46%,而原生质体溶解物中酶活性极少.研究表明,球孢白僵菌几丁质酶主要存在于细胞的周质空间,并在菌生长过程中通过细胞壁分泌至细胞外.     

Aspergillus oryzae 3.951白孢突变株的选育及其特性的研究

为改进酱油风味,作者于1984年选择了Aspergillus oryzae 3.951为出发菌株,经亚硝基胍、紫外线复合诱变处理,选育出白孢突变株,再经谷氨酰胺酶酶活筛选,获得Asp.白孢1号突变株。此菌株形态、生理特性与出发菌株相近,菌丝生长快,粗壮,浓厚,孢子白色,产孢较迟较少。蛋白酶、糖化酶酶活与出发菌株相近。谷氨酰胺酶酶活比出发菌株高34—50％,制曲后,未检出黄曲霉毒素B_1。     

抑制多种植物病原菌的几丁质酶产生菌X2-23的鉴定

样品经纹枯病菌细胞壁培养基富集后 ,从 16 6株几丁质酶产生菌中分离得到一株高产几丁质酶细菌X2 2 3.X2 2 3对所有指示菌如水稻纹枯病、稻瘟病、水稻恶苗病、小麦赤霉病、油菜菌核病以及水稻白叶枯病等多种病原菌均具强烈的拮抗作用 .当X2 2 3加入上述病原真菌的液体培养基中时 ,由光学显微镜和电子显微镜观察发现病原真菌菌丝发生扭曲、变形、菌丝细胞壁肿胀裂解、细胞质聚集、原生质体外溢或裸露等异常现象 .几丁质酶活性达 2 5 .5U/mL .该细菌经鉴定为圆孢芽孢杆菌 (Bacillusglobisporus) ,是一种新的几丁质酶产生菌 .     

2株重寄生木霉菌丝生长的生物学特性

对2株茶藨生柱锈菌(Cronartium ribicola J.C.Fischer)重寄生木霉(Trichoderma spp.)TR1、TR2菌株菌丝生长及产孢条件进行单因素筛选及正交实验。结果表明：TR1菌丝生长速度快,且极易产生分生孢子;TR2菌丝生长速度相对较慢,产孢受一定条件限制。光照和VB2能明显刺激TR2分生孢子的产生。2株菌在以大麦粉、黄豆粉、KH2PO4、复合VB为培养基,5%接种量、120r／min、pH为 6的条件下菌丝生长最佳。TR1和TR2菌丝生长的最适温度范围及水势分别为25～30℃、-232MPa和20～25℃、-454MPa.     

短小芽孢杆菌JK-SX001非蛋白抗菌物质研究

为探讨短小芽孢杆菌JK-SX001菌株非蛋白抗菌物质对杨树溃疡病的作用机制,研究了该菌株非蛋白抗菌物质的提取方法及抗菌物质对金黄壳囊孢(Cytospora chrysosperma)、拟茎点霉(Phomopsis macrospora)和七叶树壳梭孢(Fusicoccum aesculi)真菌菌丝及分生孢子的抑制机制,同时对其部分理化性质进行了测定。结果表明,JK-SX001菌株产生的非蛋白抗菌物质能强烈抑制病原真菌菌丝生长和分生孢子萌发,且能使分生孢子溶解。光照、温度对抗菌物质影响较小,而有效存储期对抗菌物质影响相对较大。     

真菌中DNA重复序列诱导点突变的研究进展

1987年,由Selker等在粗糙脉孢菌中首次发现重复序列诱导点突变(repeat-induced point mutation,RIP).在重复序列诱导点突变过程中,搜寻前减数分裂组织单倍体核中DNA的重复序列,然后发生众多的碱基C到T的突变,产生富碱基T+A片段,从而使重复序列中的G-C碱基对发生转换突变成为A-T碱基对.此外,发生RIP的序列多集中在着丝粒区域,主要是转座子甲基化后的遗迹.移动转座子是真核生物基因组进化的主要驱动力.对于真菌,重复序列诱导点突变(RIP)在减数分裂过程中通过突变多拷贝DNA,能最大限度地减少转座子的影响,因此对RIP的研究在一定程度上能有助于了解基因组进化的真谛.综述了重复序列诱导点突变的产生机制,以及真菌中重复序列诱导点突变的研究进展.     

一株生防烟管菌几丁质酶表达及抗真菌活性

为了探究烟管菌BK-1的生物防治潜力,本研究测试了一株具有生防菌活性的烟管菌BK-1的抗病效果,并使用RT-qPCR分析了该菌株的8个细胞壁裂解酶基因在与不同病原真菌对峙培养中的表达水平,结果表明,在应对链格孢、茄链格孢、尖孢镰刀菌和灰葡萄孢这4种病原真菌时,几丁质酶基因BaCHIB表达上调了27.3至50.3倍,远高于其他7个基因.BaCHIB属于糖苷水解酶18家族(GH 18),并具有Chic_BD结构域,属于B类几丁质酶(CHIB).结合基因表达谱分析,该基因诱导表达上调情况的出现与抗病效果的出现高度同步.外源表达蛋白BaCHIB显示出较高的几丁质酶活性,且表现出对多种植物病原真菌,包括链格孢,链格孢和灰葡萄孢显著的抗真菌活性,显示其对部分病原真菌具有拮抗能力.     

蜜蜂生物节律研究进展

 生物节律主要指有机体生命活动的内在节律性。蜜蜂生物节律受到其社会性的影响,从而参与许多复杂行为的调控。与果蝇相比,蜜蜂的生物节律与哺乳动物更相似。工蜂和蜂王的生物节律表现出高度的可塑性。例如,工蜂的昼夜节律受其劳动分工形式的调控,并通过与幼蜂的直接接触来调节,哺育蜂昼夜照料幼虫,在行为或时钟基因表达方面没有昼夜节律变化。从蜜蜂的社会性、蜜蜂生物节律产生的分子机制、神经基础、研究方法、可塑性、蜜蜂的睡眠等方面综述了蜜蜂生物节律的研究进展。     

Stimulated activity mediates phase shifts in the hamster circadian clock induced by dark pulses or benzodiazepines

A number of environmental and pharmacological stimuli capable of inducing phase shifts and/or period changes in the circadian clock of mammals have now been identified. Agents that can alter circadian clocks provide a means for investigating the cellular and neural mechanisms responsible for their generation, regulation and entrainment. Two stimuli that have been used to probe the basis of circadian rhythmicity are pulses of darkness on a background of constant light and injections of short-acting benzodiazepines, such as triazolam. Surprisingly, these two very different stimuli have remarkably similar phase-shifting effects on the circadian clock of hamsters. The observation that a short-term increase in locomotor activity occurs when the circadian activity rhythm of hamsters is shifted by dark pulses or triazolam injections, coupled with the finding that activity bouts themselves are capable of shifting this rhythm, raises the possibility that dark pulses or triazolam alter the circadian clock by inducing acute hyperactivity. Here we demonstrate that the phase-advancing and phase-delaying effects of dark pulses or triazolam on the circadian activity rhythm can be totally suppressed by immobilization of the animals during treatment. These results indicate that behavioural events mediate the phase-shifting effects of both dark pulses and triazolam on the circadian activity rhythm and question present hypotheses regarding the pathways by which light-dark information and pharmacological agents influence circadian pacemakers.     

Action potential mutations stop a biological clock in Drosophila

The Drosophila melanogaster male produces a species-specific courtship song by wing vibration. The most conspicuous feature of the song is a series of pulses with a 30-40-ms interpulse interval (IPI) which oscillate in wild-type males with a period of 50-60 s. This short-term biological rhythm in IPI is influenced by several gene mutations at the period (per) locus, which alter the normal 24-h free-running period of the circadian clock and have corresponding effects on the song cycle. The present study reveals that, under restrictive conditions, temperature-sensitive mutations which affect neuronal membrane excitability seem to stop the biological clock underlying the fruitfly's song rhythm.     

Constant darkness is a circadian metabolic signal in mammals

Environmental light is the 'zeitgeber' (time-giver) of circadian behaviour. Constant darkness is considered a 'free-running' circadian state. Mammals encounter constant darkness during hibernation. Ablation of the master clock synchronizer, the suprachiasmatic nucleus, abolishes torpor, a hibernation-like state, implicating the circadian clock in this phenomenon. Here we report a mechanism by which constant darkness regulates the gene expression of fat catabolic enzymes in mice. Genes for murine procolipase (mClps) and pancreatic lipase-related protein 2 (mPlrp2) are activated in a circadian manner in peripheral organs during 12 h dark:12 h dark (DD) but not light-dark (LD) cycles. This mechanism is deregulated in circadian-deficient mPer1-/-/mPer2m/m mice. We identified circadian-regulated 5'-AMP, which is elevated in the blood of DD mice, as a key mediator of this response. Synthetic 5'-AMP induced torpor and mClps expression in LD animals. Torpor induced by metabolic stress was associated with elevated 5'-AMP levels in DD mice. Levels of glucose and non-esterified fatty acid in the blood are reversed in DD and LD mice. Induction of mClps expression by 5'-AMP in LD mice was reciprocally linked to blood glucose levels. Our findings uncover a circadian metabolic rhythm in mammals.     

Research Progress on the Relationship among Circadian Rhythm,Melatonin and Aging

It is generally believed that aging is a gradual decline in the efficiency of our biological metabolism, which eventually leads to the deterioration of individual physiological function and the development of a series of age-related degenerative diseases.The circadian clock machinery orchestrates the normal metabolism of the organism in order to assure that individual growth,development and reproduction are adapted to the changes of diurnal environmental variations. The circadian rhythm in the elderly is attenuated with age and is accompanied by the onset of metabolic syndrome, the accumulation of genomic or epigenomic instability, the decline of metabolic tissue homeostasis and the change of natural feeding behavior. Existing results corroborate that light at night(LAN) and melatonin inhibition affect genomic integrity and normal metabolic function. In several animal models,LAN accelerated aging by inhibiting melatonin production in the pineal gland and promoting age-related carcinogenesis. This paper reviews the effects of the circadian rhythm on aging and discusses the complex relationship among circadian rhythms, melatonin and aging in different models of organisms, which may provide clues for prolonging human life and maintaining health.     

Unexpected features of Drosophila circadian behavioural rhythms under natural conditions

Circadian clocks have evolved to synchronize physiology, metabolism and behaviour to the 24-h geophysical cycles of the Earth. Drosophila melanogaster's rhythmic locomotor behaviour provides the main phenotype for the identification of higher eukaryotic clock genes. Under laboratory light-dark cycles, flies show enhanced activity before lights on and off signals, and these anticipatory responses have defined the neuronal sites of the corresponding morning (M) and evening (E) oscillators. However, the natural environment provides much richer cycling environmental stimuli than the laboratory, so we sought to examine fly locomotor rhythms in the wild. Here we show that several key laboratory-based assumptions about circadian behaviour are not supported by natural observations. These include the anticipation of light transitions, the midday 'siesta', the fly's crepuscular activity, its nocturnal behaviour under moonlight, and the dominance of light stimuli over temperature. We also observe a third major locomotor component in addition to M and E, which we term 'A' (afternoon). Furthermore, we show that these natural rhythm phenotypes can be observed in the laboratory by using realistic temperature and light cycle simulations. Our results suggest that a comprehensive re-examination of circadian behaviour and its molecular readouts under simulated natural conditions will provide a more authentic interpretation of the adaptive significance of this important rhythmic phenotype. Such studies should also help to clarify the underlying molecular and neuroanatomical substrates of the clock under natural protocols.