秀丽隐杆线虫模型在抗衰老研究中的应用

随着人口老龄化问题的凸显,衰老相关的研究越来越被重视。秀丽隐杆线虫（Caenorhabditis elegans）是抗衰老研究领域中非常重要的生物模型,具有生命周期短、易于培养和观察等优点,但与其他哺乳动物模型相比仍有一些局限性,如DNA甲基化的缺乏等。本文主要综述了秀丽隐杆线虫模型在抗衰老研究和药物筛选中的应用,包括抗衰老药物对线虫寿命和抗性的测定与评估、药物筛选以及健康衰老研究中的应用,并概括了该模型的优势和局限性,为秀丽隐杆线虫模型在抗衰老研究中的应用提供理论依据。     

秀丽隐杆线虫先天免疫信号转导途径

秀丽隐杆线虫因其结构简单、易于培养、生命周期短等特点作为一种模式生物已广泛应用于神经系统、衰老机制及细胞程序性死亡的研究。与高等生物不同,秀丽隐杆线虫缺少适应性免疫途径,只有先天免疫途径在抗病原菌、抗氧化应激等方面发挥重要的作用。其体内的胰岛素/胰岛素样生长因子(insulin/ IGF-1)、转化生长因子β(transforming growth factor β,TGF-β)、丝裂原激活的蛋白激酶(mitogen activated protein kinases,MAPK)和细胞程序性死亡(programmed cell death,PCD)4条免疫相关信号转导途径在不同的环境发挥着主要作用。同时,秀丽隐杆线虫的先天免疫系统在进化中有许多保守之处,这为高等生物的免疫机制研究提供了新思路。据此,就有关秀丽隐杆线虫先天免疫信号转导途径的研究进展进行了简述,期望能为人类等高等生物相关联的免疫作用研究提供借鉴和参考。     

铜对秀丽隐杆线虫毒性效应的研究

为了阐明铜(Cu)对秀丽隐杆线虫Caenorhabditis elegans长期作用的毒性效应,对实验室多代筛选的耐铜型秀丽隐杆线虫进行了寿命、衰老、发育、生殖和运动等生物学指标的研究.结果显示耐铜型秀丽隐杆线虫与野生型秀丽隐杆线虫相比其寿命缩短、衰老提前、个体发育受到抑制,且出现繁殖率降低、生殖能力减弱、运动行为存在障碍等一系列生理变化.本文为理解与阐明Cu的毒性效应提供了实验资料,有助于深入开展Cu毒性机理的研究.     

秀丽隐杆线虫模型在记忆和遗忘行为研究中的运用

记忆是学习和掌握新知识的基础,遗忘则有助于保持大脑记忆系统的高效性,因此记忆与遗忘是大脑神经网络正常运作的重要组成部分。秀丽隐杆线虫生物体积小、生命周期短、易于识别单个神经元,已成为神经科学和行为学领域研究的理想模型之一,基于秀丽隐杆线虫模型的研究结合高等模式生物探索记忆和遗忘的机制将有助于揭示记忆和遗忘异常相关疾病的发生。综述了秀丽隐杆线虫广泛用于挥发性物质与病原菌的记忆与遗忘行为的分子机制研究,以及转基因线虫在记忆与遗忘相关疾病中的应用,旨在为后续记忆和遗忘的研究提供理论参考。     

维生素C通过胰岛素信号通路增强秀丽隐杆线虫抗氧化作用

目的：利用秀丽隐杆线虫为模式生物,研究维生素C在秀丽隐杆线虫体内的抗氧化效应及其机制。方法：分别以含有0.05、0.25、0.5 mg/mL维生素C的NGM培养基饲养秀丽隐杆线虫,测定不同浓度维生素C饲养线虫体内超氧化物歧化酶（SOD）和过氧化氢酶（CAT）的含量,同时检测0.25 mg/mL的维生素C饲养线虫age-1、daf-2、daf-16、sir-2.1、clt-1基因mRNA变化。在高氧环境中,干扰0.25 mg/mL维生素C饲养线虫daf-2、daf-16基因表达检测线虫的存活情况,观察0.25 mg/mL维生素C饲养线虫DAF-16入核情况。结果：0.25 mg/mL的维生素C提高秀丽隐杆线虫体内SOD和CAT活力,在高氧环境中,0.25 mg/mL的维生素C降低age-1、daf-2基因表达,提高daf-16基因表达,同时增加DAF-16蛋白入核。结论：维生素C通过DAF-16胰岛素信号通路增强秀丽隐杆线虫抗氧化作用。     

海南岛中南部热带雨林杀秀丽隐杆线虫Bt菌株筛选

植物寄生线虫对全世界的农作物造成了严重破坏并且难以防治,迫切需要开发高效并对环境友好的生物防治策略.本研究从海南中南部的尖峰岭、五指山、大里山、鹦哥岭热带雨林共采集1613份土壤样品,筛选分离出芽孢杆菌4399份,鉴定出Bt分离株224株,Bt菌株的分离率为5.09％.以模式生物秀丽隐杆线虫作为生物测定的靶标,筛选鉴定6株Bt菌株芽孢期蛋白对秀丽隐杆线虫有较好的杀虫活性.本研究在国内是首次对海南岛热带雨林杀线虫细菌资源进行调查,获得的杀线虫Bt菌株将来有可能进一步应用于植物线虫的生物防治.     

秀丽隐杆线虫体内脂肪染色方法的探究

近几十年来,秀丽隐杆线虫(Caenorhabditis elegans)因其结构简单、通体透明、生命周期短和易于培养,常作为一种模式生物被广泛用于现代发育生物学、遗传学、抗衰老和及脂肪调控等方面的研究。本文探索了一种对秀丽隐杆线虫体内脂肪的油红O染色方法,利用1%Triton X-100的透过作用,线虫体内脂滴可被油红O更好的着色,镜下观察颜色鲜红,染色效果较好,为以后研究线虫脂肪调控奠定了基础。     

秀丽隐杆线虫脂肪沉积研究进展

脂肪的过度沉积会引发多种疾病,如心脏病、高血压、高甘油三酯血症、Ⅱ型糖尿病等。小白鼠(Mus musculus)和猪(Sus domesticus)是常用的研究脂肪沉积的模式动物,近年来随着研究的深入,发现脂肪代谢调控网络错综复杂,调控因子相互作用。秀丽隐杆线虫(Caenorhabditis elegans)具有结构简单、身体透明、便于观察、繁殖周期短、易于人工培养等特征,因此使得秀丽隐杆线虫进行脂肪调控的研究成为了可能。本文通过总结国内外线虫脂肪沉积方面的研究,综述秀丽隐杆线虫研究脂肪沉积的进展。     

秀丽隐杆线虫体内脂滴的尼罗红染色观察

秀丽隐杆线虫(Caenorhabditis elegans)为常见的生物实验模式之一,也是最近作为研究脂肪沉积的一种较理想的模型,其肠道是脂肪沉积的主要场所。本文使用尼罗红染液对秀丽隐杆线虫体内的脂肪进行染色,在荧光显微镜下可见其肠道周围呈现强烈桔黄色,较好的显示了线虫体内的脂肪沉积部位,为后续研究线虫脂肪沉积的调控机制奠定了基础。     

不同浓度亳菊水提物对秀丽隐杆线虫脂滴凝聚影响观察

目的探讨毫菊对秀丽隐杆线虫脂肪沉积的影响。方法用不同浓度毫菊水提取液配制NGM培养基,培养同步化秀丽隐杆线虫,成虫经油红0染色,异丙醇萃取,测定OD值,并与普通NGM培养基培养的同步化线虫相比较。结果随着浓度的提高,线虫体内的脂肪沉积量呈现出一定的曲线变化,其具体机制有待于进一步研究。     

Caenorhabditis elegans as a model for innate immunity to pathogens

The amenability of the nematode Caenorhabditis elegans for genetic analysis and other experimentation provides a powerful tool for studying host-pathogen interactions. Our current understanding of how C. elegans responds to pathogen challenges is in its infancy, but the discovery that the worm has inducible defence responses, which to some extent parallel those of other organisms, demonstrates the potential of this model organism for the study of innate immunity. Most progress in dissecting the C. elegans antimicrobial response has focused around signal transduction pathways and the expression of genes activated by the worm in response to microbial infections.     

Development of the appendicularian Oikopleura dioica: Culture, genome, and cell lineages

Appendicularians are planktonic tunicates (urochordates), and retain a swimming tadpole shape throughout their life. Together with ascidians, they are the closest relatives of the vertebrates. Oikopleura dioica is characterized by its simplified life habit and anatomical organization. It has a tiny genome, the smallest ever found in a chordate. Its life cycle is extremely short – about 5 days – and it can be maintained in the laboratory over many generations. Embryos and adults are transparent and consist of a small number of cells. The anatomy of juveniles and adults has been described in detail. Cleavage pattern, cell lineages, and morphogenetic movements during embryogenesis have also been comprehensively documented. A draft genome sequence is now available. These features make this organism a suitable experimental model animal in which genetic manipulations would be feasible, as in Drosophila and Caenorhabditis elegans . In this review, I summarize a hundred years' knowledge on the development throughout the life cycle of this organism. Oikopleura is an attractive organism for developmental and evolutionary studies of chordates. It offers considerable promise for future genetic approaches.     

A worm's life

Despite its relative anatomic simplicity, the nematode Caenorhabditis elegans (C. elegans) is a complex multicellular organism. In this review, we describe studies that have contributed to a better understanding of certain aspects of the worm's physiology. We focus on the cellular and molecular basis of the interaction between C. elegans and its environment, including its sensory capacities, the intrinsic biological clock that governs the speed of its life, and on some of the factors that control its life span. We also outline very recent findings that have demonstrated the existence of an innate immune system in C. elegans. Finally, we highlight a number of novel techniques that are transforming the worm from a largely genetic model system into an attractive organism for functional genomic studies.     

The nematode Panagrellus redivivus is susceptible to killing by human pathogens at 37 degrees C

Caenorhabditis elegans has been used as a host for the study of bacteria that cause disease in mammals. However, a significant limitation of the model is that C. elegans is not viable at 37 degrees C. We report that the gonochoristic nematode Panagrellus redivivus survives at 37 degrees C and maintains its life cycle at temperatures up to and including 31.5 degrees C. The C. elegans pathogens Pseudomonas aeruginosa, Salmonella enterica, Staphylococcus aureus, but not Yersinia pseudotuberculosis, reduced P. redivivus lifespan. Of four strains of Burkholderia multivorans tested, one reduced P. redivivus lifespan at both temperatures, one was avirulent at both temperatures and two strains reduced P. redivivus lifespan only at 37 degrees C. The mechanism by which one of these strains killed P. redivivus at 37 degrees C, but not at 25 degrees C, was investigated further. Killing required viable bacteria, did not involve bacterial invasion of tissues, is unlikely to be due to a diffusible, bacterial toxin and was not associated with increased numbers of live bacteria within the intestine of the worm. We believe B. multivorans may kill P. redivivus by a temperature-regulated mechanism similar to B. pseudomallei killing of C. elegans.     

Basic Caenorhabditis elegans methods: synchronization and observation

Research into the molecular and developmental biology of the nematode Caenorhabditis elegans was begun in the early seventies by Sydney Brenner and it has since been used extensively as a model organism. C. elegans possesses key attributes such as simplicity, transparency and short life cycle that have made it a suitable experimental system for fundamental biological studies for many years. Discoveries in this nematode have broad implications because many cellular and molecular processes that control animal development are evolutionary conserved. C. elegans life cycle goes through an embryonic stage and four larval stages before animals reach adulthood. Development can take 2 to 4 days depending on the temperature. In each of the stages several characteristic traits can be observed. The knowledge of its complete cell lineage together with the deep annotation of its genome turn this nematode into a great model in fields as diverse as the neurobiology, aging, stem cell biology and germ line biology. An additional feature that makes C. elegans an attractive model to work with is the possibility of obtaining populations of worms synchronized at a specific stage through a relatively easy protocol. The ease of maintaining and propagating this nematode added to the possibility of synchronization provide a powerful tool to obtain large amounts of worms, which can be used for a wide variety of small or high-throughput experiments such as RNAi screens, microarrays, massive sequencing, immunoblot or in situ hybridization, among others. Because of its transparency, C. elegans structures can be distinguished under the microscope using Differential Interference Contrast microscopy, also known as Nomarski microscopy. The use of a fluorescent DNA binder, DAPI (4',6-diamidino-2-phenylindole), for instance, can lead to the specific identification and localization of individual cells, as well as subcellular structures/defects associated to them.     

Genetic and molecular analysis of nematode-microbe interactions

Symbiosis, the living together of unlike organisms, such as between microbes and their multicellular eukaryotic hosts, can be categorized as parasitic, commensal or mutualistic. The establishment of symbiosis and the outcome of microbe-host interactions are dictated largely by both microbe- and host-derived factors. Over the last decade, the nematode Caenorhabditis elegans has provided a facile experimental system to study such interactions, with parasitic interactions being the primary focus. The myriad of genetic and molecular tools available has made C. elegans a powerful model system to interrogate the interactions between a host and its pathogens, and has provided a greater understanding of the molecular underpinnings of these interactions, many of which were found to be conserved across other taxa. Commensal and mutualistic interactions between worms and their microbes, although less studied, have the potential to enhance our understanding of genetic and molecular features underlying host-microbe interactions. Here, we highlight new insights obtained in delineating the signalling pathways that function within and between host cells in combating assaults from extracellular and intracellular pathogens. We also discuss potential new insights that could be gained from further studies into commensal and mutualistic relationships between nematodes and microbes.     

Microevolutionary studies in nematodes: a beginning

Comparisons between related species often allow the detailed genetic analysis of evolutionary processes. Here we advocate the use of the nematode Caenorhabditis elegans (and several other rhabditid species) as model systems for microevolutionary studies. Compared to Drosophila species, which have been a mainstay of such studies, C. elegans has a self-fertilizing mode of reproduction, a shorter life cycle and a convenient cell-level analysis of phenotypic variation. Data concerning its population genetics and ecology are still scarce, however. We review molecular, behavioral and developmental intraspecific polymorphisms for populations of C. elegans, Oscheius sp. 1 and Pristionchus pacificus. Focusing on vulval development, which has been well characterized in several species, we discuss relationships between patterns of variations: (1) for a given genotype (developmental variants), (2) after mutagenesis (mutability), (3) in different populations of the same species (polymorphisms) and (4) between closely related species. These studies have revealed that evolutionary variations between sister species affect those characters that show phenotypic developmental variants, that are mutable and that are polymorphic within species.     

Patterns of nucleotide polymorphism distinguish temperate and tropical wild isolates of Caenorhabditis briggsae

Caenorhabditis briggsae provides a natural comparison species for the model nematode C. elegans, given their similar morphology, life history, and hermaphroditic mode of reproduction. Despite C. briggsae boasting a published genome sequence and establishing Caenorhabditis as a model genus for genetics and development, little is known about genetic variation across the geographic range of this species. In this study, we greatly expand the collection of natural isolates and characterize patterns of nucleotide variation for six loci in 63 strains from three continents. The pattern of polymorphisms reveals differentiation between C. briggsae strains found in temperate localities in the northern hemisphere from those sampled near the Tropic of Cancer, with diversity within the tropical region comparable to what is found for C. elegans in Europe. As in C. elegans, linkage disequilibrium is pervasive, although recombination is evident among some variant sites, indicating that outcrossing has occurred at a low rate in the history of the sample. In contrast to C. elegans, temperate regions harbor extremely little variation, perhaps reflecting colonization and recent expansion of C. briggsae into northern latitudes. We discuss these findings in relation to their implications for selection, demographic history, and the persistence of self-fertilization.     

A unified statistical model for functional mapping of environment-dependent genetic expression and genotype x environment interactions for ontogenetic development

The effects of quantitative trait loci (QTL) on phenotypic development may depend on the environment (QTL x environment interaction), other QTL (genetic epistasis), or both. In this article, we present a new statistical model for characterizing specific QTL that display environment-dependent genetic expressions and genotype x environment interactions for developmental trajectories. Our model was derived within the maximum-likelihood-based mixture model framework, incorporated by biologically meaningful growth equations and environment-dependent genetic effects of QTL, and implemented with the EM algorithm. With this model, we can characterize the dynamic patterns of genetic effects of QTL governing growth curves and estimate the global effect of the underlying QTL during the course of growth and development. In a real example with rice, our model has successfully detected several QTL that produce differences in their genetic expression between two contrasting environments. These detected QTL cause significant genotype x environment interactions for some fundamental aspects of growth trajectories. The model provides the basis for deciphering the genetic architecture of trait expression adjusted to different biotic and abiotic environments and genetic relationships for growth rates and the timing of life-history events for any organism.