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1

Enhanced Glucosamine Production with Actinomucor elegans Based on Stimulating Factor of Methanol.  

PubMed

Glucosamine (GlcN) is a major and valuable component in the cell wall of fungi. In this study, the cell wall was treated via a two-stage alkali and acid process, and chitin and chitosan were fully deacetylated, partially depolymerized, and converted to GlcN oligosaccharides. Then, the oligosaccharides were analyzed by high performance liquid chromatography. The influences of Actinomucor elegans on GlcN production in a flask culture were investigated to achieve an optimum yield of GlcN. The experimental result showed that cultivation in condition of pH 6.0, 100 mL working volume (500 mL flask), 10 % (v/v) inoculum concentration, at 28 °C and 200 rpm for 6 days yielded highest dry cell weight (DCW) which was 23.43 g L(-1), with a GlcN concentration of 5.12 g L(-1). Methanol as stimulating factor was found to exert the best effect in concentration of 1.5 % (v/v). With addition of methanol into medium, the DCW increased from 23.69 to 32.42 g L(-1), leading to maximum GlcN concentration of 6.85 g L(-1) obtained. Here, the methanol addition may be useful for industrial production of GlcN, and may also be meaningful for the production of other fine chemicals by filamentous fungi. PMID:25320446

Wang, Sheng; Li, Piwu; Su, Jing; Liang, Rongrong; Wu, Xiangkun

2014-12-01

2

Abutilon theophrasti's Defense Against the Allelochemical Benzoxazolin-2(3H)-One: Support by Actinomucor elegans.  

PubMed

Abutilon theophrasti Medik., previously found to be rather insensitive to benzoxazinoid containing rye mulch and the allelochemical benzoxazolin-2(3H)-one (BOA), can be associated with the zygomycete Actinomucor elegans, whereby the fungus colonizes the root relatively superficially and mainly in the maturation zone. The fungus mitigates necrosis of the cotyledons when seedlings are incubated with 2 mM BOA, in contrast to those that lack the fungus. In liquid cultures of the fungus, tryptophan was identified. The accumulation of tryptophan is increased in presence of BOA. This amino acid seems to be important in protecting Abutilon against BOA and its derivatives since it suppressed the accumulation of BOA derived, highly toxic 2-aminophen-oxazin-3-one (APO) in the medium and on the root surface during BOA incubations of Abutilon seedlings. Although A. elegans is insensitive to BOA and APO, the fungus is not able to protect the plant against harmful effects of APO, when seedlings are treated with the compound. Abutilon can detoxify BOA via BOA-6-OH glucosylation probably by a cell wall associated glucosyltransferase, but only low amounts of the product accumulate. Low tryptophan concentrations can contribute to a degradation of the toxic intermediate BOA-6-OH by Fenton reactions, whereby the amino acid is oxidized. One of the oxidation products was identified as 4(1H)-quinolinone, which is the core substructure of the quorum sensing molecule 2-heptyl-3-hydroxy-4-quinolone. The mutualistic association of Abutilon theophrasti with Actinomucor elegans is considered as opportunistic and facultative. Such plant-fungus associations depend rather likely on environmental conditions, such as the mode of fertilization. PMID:25432667

Kia, Sevda Haghi; Schulz, Margot; Ayah, Emmanuel; Schouten, Alexander; Müllenborn, Carmen; Paetz, Christian; Schneider, Bernd; Hofmann, Diana; Disko, Ulrich; Tabaglio, Vincenzo; Marocco, Adriano

2014-12-01

3

var. brevisetum  

E-print Network

The epiphytic bryoflora of Jbel Bouhalla, a mountain sited in the Rif range (northern Morocco), is catalogued, resulting in a list of 48 taxa (45 mosses and 3 liverworts). One new variety, Orthotrichum speciosum var. brevisetum, is described, and some new records are reported: Orthotrichum shawii and O. pallens are new to northern Africa, while Habrodon perpusillus and O. speciosum var. speciosum are new to Morocco.

I. Draper; F. Lara; B. Albertos; R. Garilleti; V. Mazimpaka

2003-01-01

4

Straightening Caenorhabditis elegans images  

Microsoft Academic Search

Motivation: Caenorhabditis elegans, a roundworm found in soil, is a widely studied model organism with about 1000 cells in the adult. Producing high-resolution fluorescence images of C.elegans to reveal biological insights is becoming routine, motivating the development of advanced computational tools for analyzing the resulting image stacks. For example, worm bodies usually curve significantly in images. Thus one must 'straighten'

Hanchuan Peng; Fuhui Long; Xiao Liu; Stuart K. Kim; Eugene W. Myers

2008-01-01

5

C. elegans TRP channels  

PubMed Central

TRP (transient receptor potential) channels represent a superfamily of cation channels found in all eukaryotes. The C. elegans genome encodes seventeen TRP channels covering all of the seven TRP subfamilies. Genetic analyses in C. elegans have implicated TRP channels in a wide spectrum of behavioral and physiological processes, ranging from sensory transduction (e.g. chemosensation, touch sensation, proprioception and osmosensation) to fertilization, drug dependence, organelle biogenesis, apoptosis, gene expression, and neurotransmitter/hormone release. Many C. elegans TRP channels share similar activation and regulatory mechanisms with their vertebrate counterparts. Studies in C. elegans have also revealed some previously unrecognized functions and regulatory mechanisms of TRP channels. C. elegans represents an excellent genetic model organism for the study of function and regulation of TRP channels in vivo. PMID:21290304

Xiao, Rui; Xu, X.Z. Shawn

2010-01-01

6

Polyploids and Sex Determination in CAENORHABDITIS ELEGANS  

PubMed Central

Tetraploid stocks of Caenorhabditis elegans var. Bristol carrying autosomal and X-linked markers have been produced. Tetraploid hermaphrodites fall into two categories: those that give about 1% male self-progeny and those that give 25 to 40% male self-progeny. The former are basically 4A;4X—four sets of autosomes and four sex chromosomes—and the latter are 4A;3X. Males are 4A;2X. (Diploid hermaphrodites are 2A;2X; males are 2A;1X.) Triploids were produced by crossing tetraploid hermaphrodites and diploid males. Triploids of composition 3A;3X are hermaphrodites; 3A;2X animals are fertile males. Different X-chromosome duplications were added to a 3A;2X chromosome constitution to increase the X-to-autosome ratio. Based on the resulting sexual phenotypes, we conclude that there exists on the C. elegans X chromosome at least three (and perhaps many more) dose-sensitive sites that act cumulatively in determining sex. PMID:295035

Madl, James E.; Herman, Robert K.

1979-01-01

7

Oogenesis in Caenorhabditis elegans  

E-print Network

Oogenesis in Caenorhabditis elegans E M Maine Copyright Ã? 2001 Academic Press doi: 10.1006/rwgn.2001.0932 Maine, E M Department of Biology, Syracuse University, Syracuse, NY 13224, USA Oogenesis occur during oogenesis: the oocyte precursor germ cell undergoes meiotic division and it accumulates

Maine, Eleanor

8

Molecular cloning ofthemuscle geneunc-22 inCaenorhabditis elegans byTcltransposon tagging  

Microsoft Academic Search

Thepreviously described mutator system of Caenorhabditis elegans var.Bergerac hasasoneofits targets unc-22, apreviously uncloned geneonchromosome IVimpor- tant inassembly andfunction ofthebodywall musculature. By assuming that themutator activity involved transposition ofthe repetitive element Tclinto theunc-22 genewehavesucceeded bothincloning theunc-22 geneandindemonstrating that Tcl transposition istheprincipal basis ofthemutator activity inthe Bergerac strain. Although germ-line excision ofTclissensitive togenetic background, somatic excision appears tobeless so, suggesting thatTclmovement iscontrolled

D. G. MOERMAN; G. M. BENIAN; R. H. WATERSTON

9

RNA Interference in Caenorhabditis elegans.  

PubMed

RNAi has become an essential tool in C. elegans research. This unit describes procedures for RNAi in C. elegans by microinjecting with dsRNA, feeding with bacteria expressing dsRNA, and soaking in dsRNA solution, as well as high-throughput methods for RNAi-based screens. © 2015 by John Wiley & Sons, Inc. PMID:25559107

Conte, Darryl; MacNeil, Lesley T; Walhout, Albertha J M; Mello, Craig C

2015-01-01

10

Antioxidant Activity and Delayed Aging Effects of Hot Water Extract from Chamaecyparis obtusa var. formosana Leaves.  

PubMed

The antioxidant activity and delayed aging effects of hot water extracts from leaves of Chamaecyparis obtusa var. formosana were investigated. Free radical, superoxide radical scavenging, and total phenolic content assays were employed to evaluate the in vitro activities of the extracts. In addition, in vivo assays using the nematode Caenorhabditis elegans were also performed in this study. The results showed that among all soluble fractions obtained from the extracts, the ethyl acetate-soluble fraction has the best in vitro and in vivo antioxidant activities. Moreover, it decreased significantly the deposition of lipofuscin (aging pigment) and extended the lifespan of C. elegans. Bioactivity-guided fractionation yielded six potent antioxidant constituents from the ethyl acetate-soluble fraction, namely, catechin, quercetin, quercetin-3-O-?-rhamnoyranoside, myricetin-3-O-?-rhamnoyranoside, vanillic acid, and 4-hydroxybenzoic acid. Quercetin-3-O-?-rhamnoyranoside pretreatment showed the highest survival of C. elegans upon juglone exposure. Taken together, the results revealed that hot water extracts from C. obtusa var. formosana leaves have the potential to be used as a source for antioxidant or delayed aging health food. PMID:24766147

Cheng, Szu-Chin; Li, Wen-Hsuan; Shi, Yeu-Ching; Yen, Pei-Ling; Lin, Huan-You; Liao, Vivian Hsiu-Chuan; Chang, Shang-Tzen

2014-04-28

11

Aggregation Pheromone of Pityokteines elegans  

Microsoft Academic Search

In laboratory bioassay experiments, the beetles Pityokteines elegans were attracted to volatiles captured from bolts of grand fir, Abies grandis, colonized by P. elegans males. Male-specific volatiles detected by coupled gas chromatographic–electroantennographic detection (GC-EAD) analysis and by GC–mass spectrometry employing a chiral column were: (S)-(-)-ipsenol, (+)- and (-)-ipsdienol, and ipsenone. Field experiments demonstrated that 1:1 combinations of (-)-ipsenol and (±)-ipsdienol

J. E. Macías-Sámano; J. H. Borden; R. Gries; G. Gries

1997-01-01

12

Economics of static VAR compensation  

SciTech Connect

This project was initiated in anticipation of widened use of static VAR (volt-ampere-reactive) compensation on US bulk-power transmission systems to increase levels of secure power transfer. Project objectives were to deten-nine power system cost savings and reliability benefits resulting from such use. System operating cost and stability probabilities were compared with and without static VAR compensation, applying simulation techniques. For the particular system model studied, there was a 21.4 percent reduction in operating costs taking into account losses added by the static VAR compensator. A procedure was developed to compare instability probabilities for various loadings and static VAR compensator sizes on a power system. For the particular system model studied, the static VAR compensator provided a significant increase in stability but over a narrow range of loading. Static VAR compensation is one of a number of promising FACTS (Flexible AC Transmission System) technologies for handling the demands of increased power transfers on power systems where transmission lines cannot be built or as a short-term altemative to building additional lines.

Alvarado, F.L.; DeMarco, C.; Jung, T.H. (Wisconsin Univ., Madison, WI (United States). Dept. of Electrical and Computer Engineering)

1992-09-01

13

Meiotic Development in Caenorhabditis elegans  

PubMed Central

Caenorhabditis elegans has become a powerful experimental organism with which to study meiotic processes that promote the accurate segregation of chromosomes during the generation of haploid gametes. Haploid reproductive cells are produced through one round of chromosome replication followed by two successive cell divisions. Characteristic meiotic chromosome structure and dynamics are largely conserved in C. elegans. Chromosomes adopt a meiosis-specific structure by loading cohesin proteins, assembling axial elements, and acquiring chromatin marks. Homologous chromosomes pair and form physical connections though synapsis and recombination. Synaptonemal complex and crossover formation allow for the homologs to stably associate prior to remodeling that facilitates their segregation. This chapter will cover conserved meiotic processes as well as highlight aspects of meiosis that are unique to C. elegans. PMID:22872477

Lui, Doris Y.

2013-01-01

14

Ras pathways in Caenorhabditis elegans  

Microsoft Academic Search

The let-60 ras gene of Caenorhabditis elegans is required for multiple aspects of development. The vulval differentiation pathway is the most intensively studied of these, but the ras pathway has now been shown to also be essential for male spicule development. Using vulval differentiation, molecular genetic techniques are now being used to study structure\\/function relationships of particular signaling components and

Paul S. Kayne; Paul W. Sternberg

1995-01-01

15

Electrophysiological Methods for C. elegans Neurobiology  

PubMed Central

Patch-clamp electrophysiology is the technique of choice for the biophysical analysis of the function of nerve, muscle, and synapse in C. elegans nematodes. Considerable technical progress has been made in C. elegans electrophysiology in the decade since the initial publication of this technique. Today, most, if not all electrophysiological studies that can be done in larger animal preparations can also be done in C. elegans. This chapter has two main goals. The first is to present to a broad audience the many techniques available for patch-clamp analysis of neurons, muscles, and synapses in C. elegans. The second is to provide a methodological introduction to the techniques for patch-clamping C. elegans neurons and body-wall muscles in vivo, including emerging methods for optogenetic stimulation coupled with post-synaptic recording. We also present samples of the cell-intrinsic and post-synaptic ionic currents that can be measured in C. elegans nerve and muscle. PMID:22226532

Goodman, Miriam B.; Lindsay, Theodore H.; Lockery, Shawn R.; Richmond, Janet E.

2014-01-01

16

Touch sensitivity in Caenorhabditis elegans  

Microsoft Academic Search

The nematode Caenorhabditis elegans was the first organism for which touch insensitive mutants were obtained. The study of the genes defective in these mutants\\u000a has led to the identification of components of a mechanosensory complex needed for specific cells to sense gentle touch to\\u000a the body. Multiple approaches using genetics, cell biology, biochemistry, and electrophysiology have characterized a channel\\u000a complex,

Alexander Bounoutas; Martin Chalfie

2007-01-01

17

Sensory Transduction in Caenorhabditis elegans  

NASA Astrophysics Data System (ADS)

The roundworm Caenorhabditis elegans has a well-defined and comparatively simple repertoire of sensory-guided behaviors, all of which rely on its ability to detect chemical, mechanical or thermal stimuli. In this chapter, we review what is known about the ion channels that mediate sensation in this remarkable model organism. Genetic screens for mutants defective in sensory-guided behaviors have identified genes encoding channel proteins, which are likely transducers of chemical, thermal, and mechanical stimuli. Such classical genetic approaches are now being coupled with molecular genetics and in vivo cellular physiology to elucidate how these channels are activated in specific sensory neurons. The ion channel superfamilies implicated in sensory transduction in C. elegans - CNG, TRP, and DEG/ENaC - are conserved across phyla and also appear to contribute to sensory transduction in other organisms, including vertebrates. What we learn about the role of these ion channels in C. elegans sensation is likely to illuminate analogous processes in other animals, including humans.

Brown, Austin L.; Ramot, Daniel; Goodman, Miriam B.

18

(±)-8-oxohypecorinine from Hypecoum procumbens var. glaucescens  

Microsoft Academic Search

A new secoberbine alkaloid, (±)-8-oxohypecorinine, together with (±)-hypecorinine, isocorydine, allocryptopine, cryptopine and protopine were isolated from Hypecoum procumbens var. glaucescens and spectroscopically characterized.

Hassan-Elrady A. Saad

1995-01-01

19

Immunoglobulin Superfamily Proteins in Caenorhabditis elegans  

E-print Network

. The C. elegans IgSF proteins can be classi®ed into ®ve broad categories: muscle proteins, protein models; cell adhesion molecules; cell surface receptors; muscle proteins Introduction With completionImmunoglobulin Superfamily Proteins in Caenorhabditis elegans Sarah A. Teichmann and Cyrus Chothia

Teichmann, Sarah

20

Outline Var. integrability Var. smoothness DHR Sequence spaces Embeddings Proofs... Open problems Sobolev and Jawerth embeddings for spaces with  

E-print Network

Outline Var. integrability Var. smoothness DHR Sequence spaces Embeddings Proofs... Open problems Sobolev and Jawerth embeddings for spaces with variable smoothness and integrability January 2009 Sobolev and Jawerth embeddings for spaces with variable smoothness and integrability #12; Outline Var. integrability

Novak, Erich

21

Using C. elegans for antimicrobial drug discovery  

PubMed Central

Introduction The number of microorganism strains with resistance to known antimicrobials is increasing. Therefore, there is a high demand for new, non-toxic and efficient antimicrobial agents. Research with the microscopic nematode Caenorhabditis elegans can address this high demand for the discovery of new antimicrobial compounds. In particular, C. elegans can be used as a model host for in vivo drug discovery through high-throughput screens of chemical libraries. Areas covered This review introduces the use of substitute model hosts and especially C. elegans in the study of microbial pathogenesis. The authors also highlight recently published literature on the role of C. elegans in drug discovery and outline its use as a promising host with unique advantages in the discovery of new antimicrobial drugs. Expert opinion C. elegans can be used, as a model host, to research many diseases, including fungal infections and Alzheimer’s disease. In addition, high-throughput techniques, for screening chemical libraries, can also be facilitated. Nevertheless, C. elegans and mammals have significant differences that both limit the use of the nematode in research and the degree by which results can be interpreted. That being said, the use of C. elegans in drug discovery still holds promise and the field continues to grow, with attempts to improve the methodology already underway. PMID:21686092

Desalermos, Athanasios; Muhammed, Maged; Glavis-Bloom, Justin; Mylonakis, Eleftherios

2011-01-01

22

An overview of C. elegans biology.  

PubMed

The establishment of Caenorhabditis elegans as a "model organism" began with the efforts of Sydney Brenner in the early 1960s. Brenner's focus was to find a suitable animal model in which the tools of genetic analysis could be used to define molecular mechanisms of development and nervous system function. C. elegans provides numerous experimental advantages for such studies. These advantages include a short life cycle, production of large numbers of offspring, easy and inexpensive laboratory culture, forward and reverse genetic tractability, and a relatively simple anatomy. This chapter will provide a brief overview of C. elegans biology. PMID:16988422

Strange, Kevin

2006-01-01

23

The Neuroethology of C. elegans Escape  

PubMed Central

Escape behaviors are crucial to survive predator encounters. Touch to the head of C. elegans induces an escape response where the animal rapidly backs away from the stimulus and suppresses foraging head movements. The coordination of head and body movements facilitates escape from predacious fungi that cohabitate with nematodes in organic debris. An appreciation of the natural habitat of laboratory organisms, like C. elegans, enables a comprehensive neuroethological analysis of behavior. In this review we discuss the neuronal mechanisms and the ecological significance of the C. elegans touch response. PMID:22226513

Pirri, Jennifer K.; Alkema, Mark J.

2012-01-01

24

Gait synchronization in Caenorhabditis elegans  

PubMed Central

Collective motion is observed in swarms of swimmers of various sizes, ranging from self-propelled nanoparticles to fish. The mechanisms that govern interactions among individuals are debated, and vary from one species to another. Although the interactions among relatively large animals, such as fish, are controlled by their nervous systems, the interactions among microorganisms, which lack nervous systems, are controlled through physical and chemical pathways. Little is known, however, regarding the mechanism of collective movements in microscopic organisms with nervous systems. To attempt to remedy this, we studied collective swimming behavior in the nematode Caenorhabditis elegans, a microorganism with a compact nervous system. We evaluated the contributions of hydrodynamic forces, contact forces, and mechanosensory input to the interactions among individuals. We devised an experiment to examine pair interactions as a function of the distance between the animals and observed that gait synchronization occurred only when the animals were in close proximity, independent of genes required for mechanosensation. Our measurements and simulations indicate that steric hindrance is the dominant factor responsible for motion synchronization in C. elegans, and that hydrodynamic interactions and genotype do not play a significant role. We infer that a similar mechanism may apply to other microscopic swimming organisms and self-propelled particles. PMID:24778261

Yuan, Jinzhou; Raizen, David M.; Bau, Haim H.

2014-01-01

25

Genetics of Aging in Caenorhabditis elegans  

Microsoft Academic Search

A dissection of longevity in Caenorhabditis elegans reveals that animal life span is influenced by genes, environment, and stochastic factors. From molecules to physiology, a remarkable degree of evolutionary conservation is seen.

Adam Antebi

2007-01-01

26

Inducible systemic RNA silencing in Caenorhabditis elegans  

E-print Network

directly observed. We provide evidence that transgenic strains of Caenorhabditis elegans transcribing dsRNA from a tissue-specific promoter do not exhibit comprehensive systemic RNA interference phenotypes. In these same animals, modifications...

Timmons, Lisa; Tabara, Hiroaki; Mello, Craig C.; Fire, Andrew Z.

2003-07-01

27

Forward and reverse mutagenesis in C. elegans  

PubMed Central

Mutagenesis drives natural selection. In the lab, mutations allow gene function to be deciphered. C. elegans is highly amendable to functional genetics because of its short generation time, ease of use, and wealth of available gene-alteration techniques. Here we provide an overview of historical and contemporary methods for mutagenesis in C. elegans, and discuss principles and strategies for forward (genome-wide mutagenesis) and reverse (target-selected and gene-specific mutagenesis) genetic studies in this animal. PMID:24449699

Kutscher, Lena M.; Shaham, Shai

2014-01-01

28

Germline transformation of Caenorhabditis elegans by injection  

PubMed Central

Microinjection is a commonly used technique for DNA transformation in Caenorhabditis elegans. It is a powerful tool that links genetic and molecular analysis to phenotypic analysis. In this chapter we shall provide an overview of microinjection for germline transformation in worms. Our discussion will emphasize C. elegans reproductive biology, applications and protocols for carrying out microinjection in order to successfully obtain transgenic worms. PMID:19085141

Kadandale, Pavan; Chatterjee, Indrani; Singson, Andrew

2009-01-01

29

Automated cell lineage tracing in Caenorhabditis elegans  

Microsoft Academic Search

The invariant cell lineage and cell fate of Caenorhabditis elegans provide a unique opportunity to decode the molecular mechanisms of animal development. To exploit this opportunity, we have developed a system for automated cell lineage tracing during C. elegans embryogenesis, based on 3D, time-lapse imaging and automated image analysis. Using ubiquitously expressed histone-GFP fusion protein to label cells\\/nuclei and a

Zhirong Bao; John I. Murray; Thomas Boyle; Siew Loon Ooi; Matthew J. Sandel; Robert H. Waterston

2006-01-01

30

Natural habitat of Cryptococcus neoformans var. gattii.  

PubMed Central

Environmental isolations have established that Cryptococcus neoformans var. gattii appears to have a specific ecological association with Eucalyptus camaldulensis. So far, we have isolated C. neoformans var. gattii on 35 separate occasions, all from samples associated with E. camaldulensis. The global distribution of E. camaldulensis appears to correspond to the epidemiologic distribution of cryptococcosis caused by C. neoformans var. gattii. No other environmental source for the fungus has yet been detected, and no other eucalypt has the distribution pattern corresponding to reported cases caused by this fungus. These findings may provided an explanation for the high incidence of infections caused by C. neoformans var. gattii in Australian aborigines living in the Northern Territory and for its low worldwide incidence in acquired immunodeficiency syndrome patients. Images PMID:2199524

Ellis, D H; Pfeiffer, T J

1990-01-01

31

Ras pathways in Caenorhabditis elegans.  

PubMed

The let-60 ras gene of Caenorhabditis elegans is required for multiple aspects of development. The vulvar differentiation pathway is the most intensively studied of these, but the ras pathway has now been shown to also be essential for male spicule development. Using vulval differentiation, molecular genetic techniques are now being used to study structure/function relationships of particular signaling components and to identify new positively and negatively acting proteins of Ras-mediated signaling pathways. Mutations affecting LET-23, a receptor tyrosine kinase homolog, which cause tissue-specific defects have been localized to the carboxyl terminus. SH2 domain specificity has been analyzed through Src/SEM-5 chimeric proteins in transgenic nematodes. A mitogen-activated protein kinase that acts downstream of LET-60 Ras in vulval differentiation has been identified. Negative regulatory genes have been cloned and found to encode novel proteins and a clathrin adaptor protein. PMID:7749323

Kayne, P S; Sternberg, P W

1995-02-01

32

Cancer models in C. elegans  

PubMed Central

Although now dogma, the idea that non-vertebrate organisms such as yeast, worms, and flies could inform, and in some cases even revolutionize, our understanding of oncogenesis in humans was not immediately obvious. Aided by the conservative nature of evolution and the persistence of a cohort of devoted researchers, the role of model organisms as a key tool in solving the cancer problem has, however, become widely accepted. In this review, we focus on the nematode Caenorhabditis elegans and its diverse and sometimes surprising contributions to our understanding of the tumorigenic process. Specifically, we discuss findings in the worm that address a well-defined set of processes known to be deregulated in cancer cells including cell cycle progression, growth factor signaling, terminal differentiation, apoptosis, the maintenance of genome stability, and developmental mechanisms relevant to invasion and metastasis. PMID:20175192

Kirienko, Natalia V.; Mani, Kumaran; Fay, David S.

2013-01-01

33

Large-scale transgenesis and nerve regeneration in C. elegans  

E-print Network

Caenorhabditis elegans (C. elegans) is a widely studied model organism due to their fully mapped neural network of 302 neurons and amenable genetics. Their small size and short life cycle allows for rapid studies to be ...

Gilleland, Cody Lee

2014-01-01

34

Development of a PCR assay to identify and quantify Microdochium nivale var. nivale and Microdochium nivale var. majus in wheat  

Microsoft Academic Search

Microdochium nivaleisolates were subjected to random amplified polymorphic DNA (RAPD) assay. Amplification products common to isolates of var.majusand\\/or var.nivalewere cloned and used as probes to determine the level of cross hybridization to isolates of the opposite variety. Two clones hybridizing to either var.majusor var.nivalewere sequenced and primers generated for use in conventional PCR. The primer pair derived from a var.majusspecific

P. Nicholson; A. K. Lees; N. Maurin; D. W. Parry; H. N. Rezanoor

1996-01-01

35

Scopafungin, a Crystalline Antibiotic Produced by Streptomyces hygroscopicus var. enhygrus var. nova  

PubMed Central

Scopafungin (U-29,479) is a crystalline, nonpolyenic antimicrobial agent obtained from the culture broth of Streptomyces hygroscopicus var. enhygrus var. nova UC-2397. Scopafungin inhibits, in vitro, a variety of pathogenic fungi, yeasts, and gram-positive bacteria. PMID:4940870

Johnson, LeRoy E.; Dietz, Alma

1971-01-01

36

Morphological and molecular diversity of Agave tequilana Weber var. Azul and Agave angustifolia Haw. var. Lineño  

Microsoft Academic Search

The genetic diversity in forty-nine Agave tequilana Weber var. Azul accessions from different regions of the Appellation of Origin Tequila, and eighteen Agave angustifolia Haw. var. Lineño accessions from the south of the state of Jalisco, were evaluated using morphological traits and RAPD (Randomly Amplified Polymorphic DNA) markers. Thirteen morphological characters and three different random 10-mer primers were used. Statistical

B. Rodríguez-Garay; J. A. Lomelí-Sención; E. Tapia-Campos; A. Gutiérrez-Mora; J. García-Galindo; J. M. Rodríguez-Domínguez; D. Urbina-López; I. Vicente-Ramírez

2009-01-01

37

Host-Microbe Interactions in Caenorhabditis elegans  

PubMed Central

A good understanding of how microbes interact with hosts has a direct bearing on our capability of fighting infectious microbial pathogens and making good use of beneficial ones. Among the model organisms used to study reciprocal actions among microbes and hosts, C. elegans may be the most advantageous in the context of its unique attributes such as the short life cycle, easiness of laboratory maintenance, and the availability of different genetic mutants. This review summarizes the recent advances in understanding host-microbe interactions in C. elegans. Although these investigations have greatly enhanced our understanding of C. elegans-microbe relationships, all but one of them involve only one or few microbial species. We argue here that more research is needed for exploring the evolution and establishment of a complex microbial community in the worm's intestine and its interaction with the host. PMID:23984180

Hou, Aixin

2013-01-01

38

An overview of C. Elegans trafficking mutants.  

PubMed

It is almost 40 years since Sydney Brenner introduced Caenorhabditis elegans as a model genetic system. During that time mutants with defects in intracellular trafficking have been identified in a diverse range of screens for abnormalities. This should, of course, come as no surprise as it is hard to imagine any biological process in which the regulated movement of vesicles within the cells is not critical at some step. Almost all of these genes have mammalian homologs, and yet the role of many of these homologs has not been investigated. Perhaps the protein that regulates your favorite trafficking step has already been identified in C. elegans? Here I provide a brief overview of those trafficking mutants identified in C. elegans and where you can read more about them. PMID:11872137

Nurrish, Stephen J

2002-01-01

39

Maximally informative foraging by Caenorhabditis elegans.  

PubMed

Animals have evolved intricate search strategies to find new sources of food. Here, we analyze a complex food seeking behavior in the nematode Caenorhabditis elegans (C. elegans) to derive a general theory describing different searches. We show that C. elegans, like many other animals, uses a multi-stage search for food, where they initially explore a small area intensively ('local search') before switching to explore a much larger area ('global search'). We demonstrate that these search strategies as well as the transition between them can be quantitatively explained by a maximally informative search strategy, where the searcher seeks to continuously maximize information about the target. Although performing maximally informative search is computationally demanding, we show that a drift-diffusion model can approximate it successfully with just three neurons. Our study reveals how the maximally informative search strategy can be implemented and adopted to different search conditions. PMID:25490069

Calhoun, Adam J; Chalasani, Sreekanth H; Sharpee, Tatyana O

2014-01-01

40

Volatiles of Chrysanthemum zawadskii var. latilobum K  

PubMed Central

The volatile aroma constituents of Chrysanthemum zawadskii var. latilobum K. were separated by hydro distillation extraction (HDE) method using a Clevenger-type apparatus, and analyzed by gas chromatography-mass spectrometry (GC/MS). The yield of C. zawadskii var. latilobum K. flower essential oil (FEO) was 0.12% (w/w) and the color was light green. Fifty-five volatile chemical components, which make up 88.38% of the total aroma composition, were tentatively characterized. C. zawadskii var. latilobum K. FEOs contained 27 hydrocarbons, 12 alcohols, 7 ketones, 4 esters, 1 aldehyde, 1 amine, and 3 miscellaneous components. The major functional groups were terpene alcohol and ketone. Borneol (12.96), (±)-7-epi-amiteol (12.60), and camphor (10.54%) were the predominant volatiles. These compounds can be used in food and pharmaceutical industries due to their active bio-functional properties. PMID:24471090

Chang, Kyung-Mi; Kim, Gun-Hee

2012-01-01

41

Volatiles of Chrysanthemum zawadskii var. latilobum K.  

PubMed

The volatile aroma constituents of Chrysanthemum zawadskii var. latilobum K. were separated by hydro distillation extraction (HDE) method using a Clevenger-type apparatus, and analyzed by gas chromatography-mass spectrometry (GC/MS). The yield of C. zawadskii var. latilobum K. flower essential oil (FEO) was 0.12% (w/w) and the color was light green. Fifty-five volatile chemical components, which make up 88.38% of the total aroma composition, were tentatively characterized. C. zawadskii var. latilobum K. FEOs contained 27 hydrocarbons, 12 alcohols, 7 ketones, 4 esters, 1 aldehyde, 1 amine, and 3 miscellaneous components. The major functional groups were terpene alcohol and ketone. Borneol (12.96), (±)-7-epi-amiteol (12.60), and camphor (10.54%) were the predominant volatiles. These compounds can be used in food and pharmaceutical industries due to their active bio-functional properties. PMID:24471090

Chang, Kyung-Mi; Kim, Gun-Hee

2012-09-01

42

Eph receptor signaling in C. elegans  

PubMed Central

Eph receptor protein-tyrosine kinases are among the oldest known animal receptors and have greatly expanded in number during vertebrate evolution. Their complex transduction mechanisms are capable of bidirectional and bimodal (multi-response) signaling. Eph receptors are expressed in almost every cell type in the human body, yet their roles in development, physiology, and disease are incompletely understood. Studies in C. elegans have helped identify biological functions of these receptors, as well as transduction mechanisms. Here we review advances in our understanding of Eph receptor signaling made using the C. elegans model system. PMID:23197476

Miller, Michael A.; Chin-Sang, Ian D.

2014-01-01

43

The basking behavior of Trachemys scripta elegans  

E-print Network

THE BASKING BEHAVIOR OFT~RACHEMY BCIHFTA~ELEGAN A Thesis LISA MAUREEN MCDONALD Submitted to the Office of Graduate Studies of Texas ABiM University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE August 1992... Major Subject; Zoology THE BASKING BEHAVIOR OF TRACHEMYS ~SRIPfA ELEGANS A Thesis LISA MAUREEN MCDONALD Merrill H. Sweet, II (Co-Chair of Committee) James R. D' on o-Chair of ommittee) David W. Owens (Member) Timothy . Hall (Head of Department...

McDonald, Lisa Maureen

1992-01-01

44

Absence of Strong Heterosis for Life Span and Other Life History Traits in Caenorhabditis Elegans  

PubMed Central

We have examined crosses between wild-type strains of Caenorhabditis elegans for heterosis effects on life span and other life history traits. Hermaphrodites of all wild strains had similar life expectancies but males of two strains had shorter life spans than hermaphrodites while males of two other strains lived longer than hermaphrodites. F(1) hermaphrodite progeny showed no heterosis while some heterosis for longer life span was detected in F(1) males. F(1) hybrids of crosses between two widely studied wild-type strains, N2 (var. Bristol) and Berg BO (var. Bergerac), were examined for rate of development, hermaphrodite fertility, and behavior; there was no heterosis for these life history traits. Both controlled variation of temperature and uncontrolled environmental variation affected the length of life of all genotypes. Significant G X E effects on life span were observed in comparisons of N2 and Berg BO hermaphrodites, or N2 hermaphrodites and males, or N2 and a Ts mutant strain (DH26). Nevertheless, within an experiment, environmental variation was minimal and life spans were quite replicable. PMID:8325483

Johnson, T. E.; Hutchinson, E. W.

1993-01-01

45

A protocol to infect Caenorhabditis elegans with Salmonella typhimurium.  

PubMed

In the last decade, C. elegans has emerged as an invertebrate organism to study interactions between hosts and pathogens, including the host defense against gram-negative bacterium Salmonella typhimurium. Salmonella establishes persistent infection in the intestine of C. elegans and results in early death of infected animals. A number of immunity mechanisms have been identified in C. elegans to defend against Salmonella infections. Autophagy, an evolutionarily conserved lysosomal degradation pathway, has been shown to limit the Salmonella replication in C. elegans and in mammals. Here, a protocol is described to infect C. elegans with Salmonella typhimurium, in which the worms are exposed to Salmonella for a limited time, similar to Salmonella infection in humans. Salmonella infection significantly shortens the lifespan of C. elegans. Using the essential autophagy gene bec-1 as an example, we combined this infection method with C. elegans RNAi feeding approach and showed this protocol can be used to examine the function of C. elegans host genes in defense against Salmonella infection. Since C. elegans whole genome RNAi libraries are available, this protocol makes it possible to comprehensively screen for C. elegans genes that protect against Salmonella and other intestinal pathogens using genome-wide RNAi libraries. PMID:24998902

Zhang, Jiuli; Jia, Kailiang

2014-01-01

46

Endomesoderm specification in Caenorhabditis elegans and  

E-print Network

of the posterior half of the feeding organ (the pharynx), one third of the animal's body wall muscles,7) Overview of the C. elegans endomesoderm GRN A ``process diagram`` incorporating the salient features pathways, embryonic genes generally belong to one of three broad categories as summarized in Fig. 3: (1

Maduro, Morris F.

47

Collaborative homologous pairing during C. elegans meiosis  

PubMed Central

In preparation for meiotic chromosome segregation, homologous chromosomes need to pair, synapse (i.e., assemble the synaptonemal complex, SC), and then recombine to generate a physical linkage (i.e., chiasma) between them. In many organisms meiotic pairing capacity distributed along the entire chromosome length supports presynaptic alignment. In contrast, the prevailing model for C. elegans proposes that presynaptic homologous pairing is performed solely by a master pairing-site, the pairing center (PC). In this model, the remaining chromosomal regions (the non-PC regions) are not actively involved in presynaptic pairing, and the SC assembling from the PC aligns the homologous chromosomes along non-PC regions and holds them together. Our recent work, however, demonstrates that C. elegans chromosomes establish presynaptic alignment along the entire chromosome length, suggesting that the non-PC regions are also actively involved in the presynaptic pairing process. Furthermore, we have also discovered that the chromodomain protein MRG-1 facilitates this presynaptic non-PC pairing. The phenotype of the mrg-1 mutant indicates that the PC and the non-PC collaborate in successful pairing and synapsis. Therefore, homologous pairing mechanisms in C. elegans possibly share more similarity with those in other organisms than previously thought. Here, we elaborate on these observations and discuss a hypothetical model for presynaptic pairing in C. elegans based on our novel findings. PMID:24058834

Nabeshima, Kentaro

2012-01-01

48

Comparative Toxicology of Mercurials in Caenorhabditis elegans  

PubMed Central

Mercury is a toxic metal that can exist in multiple chemical species. Humans are commonly exposed to methylmercury and mercury vapor, which is converted to mercuric mercury in the body. Despite years of research, there is a paucity of information on the similarity and differences in the mechanisms of mercury toxicity. The relative toxicity of mercuric chloride (HgCl2) and methylmercury chloride (MeHgCl) in C. elegans was determined using assays that measured growth, feeding, reproduction, and locomotion. The effect of HgCl2 and MeHgCl on the expression of several archetypal stress-response genes was also determined. There was no significant difference between the EC50s of the two mercurials on C. elegans growth. However, MeHgCl was more toxic to C. elegans than HgCl2 when assessing feeding, movement and reproduction, all of which require proper neuromuscular activity. Methylmercury chloride exposure resulted in increased steady-state levels of the stress response genes at lower concentrations than HgCl2. In general, MeHgCl was more toxic to C. elegans than HgCl2, particularly when assaying behaviors that require neuromuscular function. PMID:21692103

McElwee, Matthew K.; Freedman, Jonathan H.

2011-01-01

49

THE GENETICS OF CAENOR?ABDITIS ELEGANS  

Microsoft Academic Search

Methods are described for the isolation, complementation and mapping of mutants of Caenorhabditis elegans, a small free-living nematode worm. About 300 EMS-induced mutants affecting behavior and morphology have been char- acterized and about one hundred genes have been defined. Mutations in 77 of these alter the movement of the animal. Estimates of the induced mutation frequency of both the visible

S. BRENNER

1974-01-01

50

Calcium dynamics during fertilization in C. elegans  

PubMed Central

Background Of the animals typically used to study fertilization-induced calcium dynamics, none is as accessible to genetics and molecular biology as the model organism Caenorhabditis elegans. Motivated by the experimental possibilities inherent in using such a well-established model organism, we have characterized fertilization-induced calcium dynamics in C. elegans. Results Owing to the transparency of the nematode, we have been able to study the calcium signal in C. elegans fertilization in vivo by monitoring the fluorescence of calcium indicator dyes that we introduce into the cytosol of oocytes. In C. elegans, fertilization induces a single calcium transient that is initiated soon after oocyte entry into the spermatheca, the compartment that contains sperm. Therefore, it is likely that the calcium transient is initiated by contact with sperm. This calcium elevation spreads throughout the oocyte, and decays monotonically after which the cytosolic calcium concentration returns to that preceding fertilization. Only this single calcium transient is observed. Conclusion Development of a technique to study fertilization induced calcium transients opens several experimental possibilities, e.g., identification of the signaling events intervening sperm binding and calcium elevation, identifying the possible roles of the calcium elevation such as the completion of meiosis, the formation of the eggshell, and the establishing of the embryo's axis of symmetry. PMID:11346453

Samuel, Aravinthan DT; Murthy, Venkatesh N; Hengartner, Michael O

2001-01-01

51

Mitochondrial bioenergetics and disease in Caenorhabditis elegans.  

PubMed

Simple multicellular animal model systems are central to studying the complex mechanisms underlying a bewildering array of diseases involving dysfunctional mitochondria. Mutant nuclear- and mitochondrial-encoded subunits of the Caenorhabditis elegans mitochondrial respiratory chain (MRC) have been investigated, including GAS-1, NUO-1, NUO-6, MEV-1, SDHB-1, CLK-1, ISP-1, CTB-1, and ATP-2. These, as well as proteins that modify the MRC indirectly, have been studied on the molecular, cellular, and organismal levels through the variety of experimental approaches that are readily achievable in C. elegans. In C. elegans, MRC dysfunction can mimic signs and symptoms observed in human patients with primary mitochondrial disorders, such as neuromuscular deficits, developmental delay, altered anesthetic sensitivity, and increased lactate levels. Antioxidant dietary supplements, coenzyme Q substitutes, and flavin cofactors have been explored as potential therapeutic strategies. Furthermore, mutants with altered longevity have proved useful for probing the contributions of bioenergetics, reactive oxygen species, and stress responses to the process of aging. C. elegans will undoubtedly continue to provide a useful system in which to explore unanswered questions in mitochondrial biology and disease. PMID:25553447

Dancy, Beverley M; Sedensky, Margaret M; Morgan, Philip G

2015-01-01

52

Movie of normal C. elegans development  

NSDL National Science Digital Library

C. elegans develops from a single cell, the fertilized egg, to a 558-celled worm in about 14 hours. The worm that crawls out of its eggshell has a functioning feeding apparatus, gut, nervous system and muscles. This movie shows that in time lapse.

PhD Bob Goldstein (UNC Chapel Hill Biology Dept,)

2006-07-19

53

Coordinated adaptive distribution volt\\/VAr controls  

Microsoft Academic Search

This paper presents the philosophy and field results of beta tests of an adaptive system for controlling distribution voltages and VAr flows. This system includes adaptive pole-top capacitor bank controls (ACCs), an adaptive transformer LTC voltage control (ATC) and an adaptive line regulator control (ARC). This adaptive system consists of these distributed intelligent devices, independent of outside communication, to accomplish

E. T. Jauch; M. V. V. S. Yalla; A. P. Craig

1999-01-01

54

Salmonella enterica var Typhimurium and Salmonella enterica var Enteritidis express type 1 fimbriae in the rat in vivo  

Microsoft Academic Search

In a series of experiments rats were dosed with purified type 1 fimbriae from Salmonella enterica var Enteritidis or with fimbriated cultures of either S. enterica var Typhimurium or S. enterica var Enteritidis. Paraffin-wax embedded histological sections of jejunal and ileal tissue were taken and stained by the streptavidin biotin complex (sABC) staining technique for the detection of salmonella and

Stanley W. B Ewen; Patrick J Naughton; George Grant; Marcjanna Sojka; Emma Allen-Vercoe; Susan Bardocz; Christopher J Thorns; Arpad Pusztai

1997-01-01

55

Basic Caenorhabditis elegans methods: synchronization and observation.  

PubMed

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. PMID:22710399

Porta-de-la-Riva, Montserrat; Fontrodona, Laura; Villanueva, Alberto; Cerón, Julián

2012-01-01

56

Hormetic effect of methylmercury on Caenorhabditis elegans  

SciTech Connect

Research has demonstrated the toxic effects of methylmercury (MeHg), yet molecular mechanisms underlying its toxicity are not completely understood. Caenorhabditis elegans (C. elegans) offers a unique biological model to explore mechanisms of MeHg toxicity given many advantages associated with its ease of use and genetic power. Since our previous work indicated neurotoxic resistance of C. elegans to MeHg, the present study was designed to examine molecular mechanisms associated with this resistance. We hypothesized MeHg would induce expression of gst, hsp or mtl in vivo since glutathione (GSH), heat shock proteins (HSPs), and metallothioneins (MTs) have shown involvement in MeHg toxicity. Our studies demonstrated a modest, but significant increase in fluorescence in gst-4::GFP and mtl-1::GFP strains at an acute, low L1 MeHg exposure, whereas chronic L4 MeHg exposure induced expression of gst-4::GFP and hsp-4::GFP. Knockout gst-4 animals showed no alterations in lethality sensitivity compared to wildtype animals whereas mtl knockouts displayed increased sensitivity to MeHg exposure. GSH levels were increased by acute MeHg treatment and depleted with chronic exposure. We also demonstrate that MeHg induces hormesis, a phenotype whereby a sublethal exposure to MeHg rendered C. elegans resistant to subsequent exposure to the organometal. The involvement of gst-4, hsp-4, mtl-1, and mtl-2 in hormesis was examined. An increase in gst-4::GFP expression after a low-dose acute exposure to MeHg indicated that gst-4 may be involved in this response. Our results implicate GSH, HSPs, and MTs in protecting C. elegans from MeHg toxicity and show a potential role of gst-4 in MeHg-induced hormesis.

Helmcke, Kirsten J., E-mail: Kirsten.J.Helmcke@gmail.com; Aschner, Michael, E-mail: Michael.Aschner@vanderbilt.ed

2010-10-15

57

Hormetic effect of methylmercury on Caenorhabditis elegans  

PubMed Central

Research has demonstrated the toxic effects of methylmercury (MeHg), yet molecular mechanisms underlying its toxicity are not completely understood. Caenorhabditis elegans (C. elegans) offers a unique biological model to explore mechanisms of MeHg toxicity given many advantages associated with its ease of use and genetic power. Since our previous work indicated neurotoxic resistance of C. elegans to MeHg, the present study was designed to examine molecular mechanisms associated with this resistance. We hypothesized MeHg would induce expression of gst, hsp or mtl in vivo since glutathione (GSH), heat shock proteins (HSPs), and metallothioneins (MTs) have shown involvement in MeHg toxicity. Our studies demonstrated a modest, but significant increase in fluorescence in gst-4::GFP and mtl-1::GFP strains at an acute, low L1 MeHg exposure, whereas chronic L4 MeHg exposure induced expression of gst-4::GFP and hsp-4::GFP. Knockout gst-4 animals showed no alterations in lethality sensitivity compared to wildtype animals whereas mtl knockouts displayed increased sensitivity to MeHg exposure. GSH levels were increased by acute MeHg treatment and depleted with chronic exposure. We also demonstrate that MeHg induces hormesis, a phenotype whereby a sublethal exposure to MeHg rendered C. elegans resistant to subsequent exposure to the organometal. The involvement of gst-4, hsp-4, mtl-1, and mtl-2 in hormesis was examined. An increase in gst-4::GFP expression after a low-dose acute exposure to MeHg indicated that gst-4 may be involved in this response. Our results implicate GSH, HSPs, and MTs in protecting C. elegans from MeHg toxicity and show a potential role of gst-4 in MeHg-induced hormesis. PMID:20691719

Helmcke, Kirsten J.; Aschner, Michael

2010-01-01

58

Granulicatella elegans Causing Periorbital Infection During Orthodontic Treatment.  

PubMed

Granulicatella elegans is a normal component of the oral flora and is an unusual causative agent of infective endocarditis. A case of G. elegans periorbital infection of the eyelid after dental treatment is reported. A healthy 35-year-old man presented with painful swelling of the left upper eyelid. He was empirically treated with oral amoxicillin for 1 week. He presented 3 months later with the same clinical features. G. elegans and Staphylococcus epidermidis were identified in bacterial cultures from wound aspirates. Probable relapse of periorbital infection was successfully treated with a 6-week course of oral amoxicillin. This is the first reported case of a non-bloodstream infection caused by G. elegans. Clinicians should be aware of G. elegans as an unusual causative agent of periorbital infection. Within the limitations of this case report, prolonged antibiotic therapy is recommended for a G. elegans periorbital infection to minimize the risk of relapse. PMID:25105523

Kim, Yong Joon; Choi, Bo Mi; Choi, Kyung Seek

2014-08-01

59

Receptor-mediated Endocytosis in the Caenorhabditis elegans Oocyte  

Microsoft Academic Search

The Caenorhabditis elegans oocyte is a highly amenable system for forward and reverse genetic analysis of receptor-mediated endocytosis. We describe the use of transgenic strains expressing a vitellogenin::green fluorescent protein (YP170::GFP) fusion to monitor yolk endocytosis by the C. elegans oocyte in vivo. This YP170::GFP reporter was used to assay the functions of C. elegans predicted proteins homologous to vertebrate

Barth Grant; David Hirsh

1999-01-01

60

Bacteria and the Aging and Longevity of Caenorhabditis elegans  

E-print Network

The molecular genetic analysis of longevity of Caenorhabditis elegans has yielded fundamental insights into evolutionarily conserved pathways and processes governing the physiology of aging. Recent studies suggest that ...

Kim, Dennis H.

61

PROPUESTA DE ACTIVIDAD TIC-VAR-005  

E-print Network

PROPUESTA DE ACTIVIDAD ACAD�MICA TIC-VAR-005 TIPO DE ACTIVIDAD1 : PFC, PPG, TM ÁREA2 : TIC TÍTULO Mozambique PERSONA QUE PROPONE Mª Fernanda Dulcey, Coordinadora de TICs Teléfono o correo-e de contacto específico, sin que tenga necesariamente un fin académico. 2 TIC, Agua, Energía, Desarrollo Agropecuario y

Autonoma de Madrid, Universidad

62

Withanolides from Jaborosa caulescens var. bipinnatifida  

PubMed Central

Two new withanolides 2,3-dihydrotrechonolide A (1) and 2,3-dihydro-21-hydroxytrechonolide A (2) were isolated along with two known withanolides trechonolide A (3) and jaborosalactone 39 (4) from Jaborosa caulescens var. bipinnatifida (Solanaceae). The structures of 1-2 were elucidated through 2D NMR and other spectroscopic techniques. In addition, the structure of withanolide 1 was confirmed by X-ray crystallographic analysis. PMID:24314746

Zhang, Huaping; Cao, Cong-Mei; Gallagher, Robert J.; Day, Victor W.; Montenegro, Gloria; Timmermann, Barbara N.

2013-01-01

63

C. elegans Gene Index (CeGI)  

NSDL National Science Digital Library

The Institute for Genomic Research (TIGR) has released the C. elegans Gene Index (CeGI), including over 22,900 unique sequences (TCs, ETs, and ESTs). CeGI includes data files (FASTA) "containing the complete, minimally redundant C. elegans Index (TCs and singletons),... the complete set of TC sequences in the Index (with previous TC identities in the definition line), ... [and] a file containing the TC id's and the ESTs that comprise them." The Index is searchable by Nucleotide or Protein Sequence, Identifier (TC, ET, EST, GB), or Tissue, cDNA Library Name, or cDNA Library Identifier(cat#). Note that all data in CeGI are "freely available to researchers at nonprofit institutions using them for non-commercial purposes."

64

Metal-induced neurodegeneration in C. elegans  

PubMed Central

The model species, Caenorhabditis elegans, has been used as a tool to probe for mechanisms underlying numerous neurodegenerative diseases. This use has been exploited to study neurodegeneration induced by metals. The allure of the nematode comes from the ease of genetic manipulation, the ability to fluorescently label neuronal subtypes, and the relative simplicity of the nervous system. Notably, C. elegans have approximately 60–80% of human genes and contain genes involved in metal homeostasis and transport, allowing for the study of metal-induced degeneration in the nematode. This review discusses methods to assess degeneration as well as outlines techniques for genetic manipulation and presents a comprehensive survey of the existing literature on metal-induced degeneration studies in the worm. PMID:23730287

Chen, Pan; Martinez-Finley, Ebany J.; Bornhorst, Julia; Chakraborty, Sudipta; Aschner, Michael

2013-01-01

65

Mechanisms of iron metabolism in Caenorhabditis elegans  

PubMed Central

Iron is involved in many biological processes essential for sustaining life. In excess, iron is toxic due to its ability to catalyze the formation of free radicals that damage macromolecules. Organisms have developed specialized mechanisms to tightly regulate iron uptake, storage and efflux. Over the past decades, vertebrate model organisms have led to the identification of key genes and pathways that regulate systemic and cellular iron metabolism. This review provides an overview of iron metabolism in the roundworm Caenorhabditis elegans and highlights recent studies on the role of hypoxia and insulin signaling in the regulation of iron metabolism. Given that iron, hypoxia and insulin signaling pathways are evolutionarily conserved, C. elegans provides a genetic model organism that promises to provide new insights into mechanisms regulating mammalian iron metabolism. PMID:24904417

Anderson, Cole P.; Leibold, Elizabeth A.

2014-01-01

66

The C. elegans lifespan assay toolkit.  

PubMed

Since the discovery of single gene mutations that double its lifespan, the nematode Caenorhabditis elegans has provided remarkable insights into the biology of aging. The precisely measurable lifespan of worms has proven to be an efficient tool to assess the impact of various genetic, physiological and environmental factors on organismal aging. In this article, we describe methods to set up and monitor experiments to determine worm lifespan. We include procedures used for classical, small-scale lifespan assays that are generally performed on solid media, and review recent advances in high-throughput, automated longevity experiments conducted in liquid culture and microfluidic devices. In addition, tools that help analyze this data to obtain survival statistics are summarized, and C. elegans strains that offer particular advantages for lifespan studies are listed. PMID:24727064

Amrit, Francis Raj Gandhi; Ratnappan, Ramesh; Keith, Scott Alexander; Ghazi, Arjumand

2014-08-01

67

Circadian stress tolerance in adult Caenorhabditis elegans  

Microsoft Academic Search

Circadian rhythms control several behaviors through neural networks, hormones and gene expression. One of these outputs in\\u000a invertebrates, vertebrates and plants is the stress resistance behavior. In this work, we studied the circadian variation\\u000a in abiotic stress resistance of adult C. elegans as well as the genetic mechanisms that underlie such behavior. Measuring the stress resistance by tap response behavior

Sergio H. Simonetta; Andrés Romanowski; Alicia N. Minniti; Nibaldo C. Inestrosa; Diego A. Golombek

2008-01-01

68

Automated cell lineage tracing in Caenorhabditis elegans  

PubMed Central

The invariant cell lineage and cell fate of Caenorhabditis elegans provide a unique opportunity to decode the molecular mechanisms of animal development. To exploit this opportunity, we have developed a system for automated cell lineage tracing during C. elegans embryogenesis, based on 3D, time-lapse imaging and automated image analysis. Using ubiquitously expressed histone–GFP fusion protein to label cells/nuclei and a confocal microscope, the imaging protocol captures embryogenesis at high spatial (31 planes at 1 ?m apart) and temporal (every minute) resolution without apparent effects on development. A set of image analysis algorithms then automatically recognizes cells at each time point, tracks cell movements, divisions and deaths over time and assigns cell identities based on the canonical naming scheme. Starting from the four-cell stage (or earlier), our software, named starrynite, can trace the lineage up to the 350-cell stage in 25 min on a desktop computer. The few errors of automated lineaging can then be corrected in a few hours with a graphic interface that allows easy navigation of the images and the reported lineage tree. The system can be used to characterize lineage phenotypes of genes and/or extended to determine gene expression patterns in a living embryo at the single-cell level. We envision that this automation will make it practical to systematically decipher the developmental genes and pathways encoded in the genome of C. elegans. PMID:16477039

Bao, Zhirong; Murray, John I.; Boyle, Thomas; Ooi, Siew Loon; Sandel, Matthew J.; Waterston, Robert H.

2006-01-01

69

Proteins Interacting With Caenorhabditis elegans ?G? Subunits  

PubMed Central

To identify novel components in heterotrimeric G-protein signalling, we performed an extensive screen for proteins interacting with Caenorhabditis elegans G? subunits. The genome of C. elegans contains homologues of each of the four mammalian classes of G? subunits (Gs, Gi/o, Gq and G12), and 17 other G? subunits. We tested 19 of the GG? subunits and four constitutively activated G? subunits in a largescale yeast two-hybrid experiment. This resulted in the identification of 24 clones, representing 11 different proteins that interact with four different G? subunits. This set includes C. elegans orthologues of known interactors of G? subunits, such as AGS3 (LGN/PINS), CalNuc and Rap1Gap, but also novel proteins, including two members of the nuclear receptor super family and a homologue of human haspin (germ cell-specific kinase). All interactions were found to be unique for a specific G? subunit but variable for the activation status of the G? subunit. We used expression pattern and RNA interference analysis of the G-protein interactors in an attempt to substantiate the biological relevance of the observed interactions. Furthermore, by means of a membrane recruitment assay, we found evidence that GPA-7 and the nuclear receptor NHR-22 can interact in the animal. PMID:18629017

Cuppen, Edwin; van der Linden, Alexander M.; Jansen, Gert

2003-01-01

70

Modeling neurodegenerative diseases in Caenorhabditis elegans.  

PubMed

Neurodegenerative diseases which include Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), Huntington disease (HD), and others are becoming an increasing threat to human health worldwide. The degeneration and death of certain specific groups of neurons are the hallmarks of these diseases. Despite the research progress in identification of several disease-related genes, the mechanisms underlying the neurodegeneration in these diseases remain unclear. Given the molecular conservation in neuronal signaling between Caenorhabditis elegans and vertebrates, an increasing number of research scientists have used the nematode to study this group of diseases. This review paper will focus on the model system that has been established in C. elegans to investigate the pathogenetic roles of those reported disease-related genes in AD, PD, ALS, HD and others. The progress in C. elegans provides useful information of the genetic interactions and molecular pathways that are critical in the disease process, and may help better our understanding of the disease mechanisms and search for new therapeutics for these devastating diseases. PMID:24095843

Li, Jia; Le, Weidong

2013-12-01

71

Counting Mutagenized Genomes and Optimizing Genetic Screens in Caenorhabditis elegans  

E-print Network

. Since genetic screens often entail examination of thousands or tens of thousands of animals, strategies Caenorhabditis elegans. Here we review general principles of genetic screens in C. elegans, and use a modified in the genetic analysis of a biological process. In animals amenable to genetic study, such mutants are commonly

Shaham, Shai

72

THE CAENORHABDITIS ELEGANS GENOME PROJECT Sean R. Eddy  

E-print Network

cerevisiae (Oliver et al., 1992). Sydney Brenner became interested in C. elegans in the 1960s as a model genetic sys­ tem for the study of nervous system development and animal behavior (Brenner, 1974). Since that time, a growing community of C. elegans researchers has extended Brenner's already ambitious vision

Eddy, Sean

73

Specificity and Complexity of the Caenorhabditis elegans Innate Immune Response  

Microsoft Academic Search

In response to infection, Caenorhabditis elegans produces an array of antimicrobial proteins. To understand the C. elegans immune response, we have investigated the regulation of a large, representative sample of candidate antimicrobial genes. We found that all these putative antimicrobial genes are expressed in tissues exposed to the environment, a position from which they can ward off infection. Using RNA

Scott Alper; Sandra J. McBride; Brad Lackford; Jonathan H. Freedman; David A. Schwartz

2007-01-01

74

Locomotion Control of Caenorhabditis elegans through Confinement Felix Lebois,  

E-print Network

#12;Locomotion Control of Caenorhabditis elegans through Confinement Fe´lix Lebois, Pascal Sauvage organism Caenorhabditis elegans shows two distinct locomotion patterns in laboratory situations: it swims in the regulation of locomotion and in the gait selection. Using an original device, we present what to our

Hersen, Pascal - Laboratoire Matière et Systèmes Complexes, Université Paris 7

75

Sesquiterpenes from Thapsia nitida var. meridionalis and Thapsia nitida var. nitida.  

PubMed

Nine new eudesmanolides (1-9), two new guaianolides (12 and 13), and a new germacrane (10), along with a previously reported guaianolide (11), have been isolated from the roots of Thapsia nitida var. meridionalis. Thapsia nitida var. nitida also afforded compound 13 along with a new guaianolide (14). The structure of 13 was confirmed by X-ray crystallographic analysis. Compounds 1, 2, and 11-14 have been tested as potential inhibitors of the sarco- and endoplasmic Ca2+-dependent ATPases (SERCA) pump. None of them showed significant activities. PMID:17125222

Rubal, Juan J; Guerra, Francisco M; Moreno-Dorado, F Javier; Jorge, Zacarías D; Massanet, Guillermo M; Søhoel, Helmer; Smitt, Ulla W; Frydenvang, Karla; Christensen, S Brøgger; Nielsen, Charlotte; Eriksson, Margit

2006-11-01

76

The Caenorhabiditis elegans model as a reliable tool in neurotoxicology.  

PubMed

Caenorhabiditis elegans (C. elegans) offers an attractive experimental platform as it has a short life cycle, is inexpensive to maintain and most importantly has high degree of evolutionary conservation with higher eukaryotes. Understanding the contribution of inherent genes that regulate neurotoxicity and antioxidant stress responses in the worm provides critical insight into mechanisms of mammalian neurotoxicity. The C. elegans model readily enables multi-gene approach, allowing for combinatorial genetic variation to be studied within the context of the influence of multigenic polymorphisms in environmental risk and vulnerability. This review provides a synopsis of recent studies on metal and pesticides toxicity in C. elegans, highlighting the utility of the model system in understanding molecular mechanisms that underlie developmental, reproductive and neuronal damage. The continuation of these investigations combining basic toxicological experimentation with novel genetic and high throughput methods will continue to make C. elegans an invaluable tool for future research, providing insight into molecular and cellular mechanisms of toxicity. PMID:21148196

Avila, Daiana; Helmcke, Kirsten; Aschner, Michael

2012-03-01

77

Evaluation of morphological and molecular variation in Plantago asiatica var. densiuscula , with special reference to the systematic treatment of Plantago asiatica var. yakusimensis  

Microsoft Academic Search

Morphological and molecular variations in Plantago asiatica L. var. densiuscula Pilg. were analyzed to evaluate the genetic basis for recognizing the dwarf variety P. asiatica var. yakusimensis (Masam.) Ohwi. Considerable variation in the leaf size of P. asiatica var. densiuscula was observed, and no morphological discontinuities were found between the dwarf types of P. asiatica var. densiuscula and P. asiatica

Naoko Ishikawa; Jun Yokoyama; Hiroshi Ikeda; Eriko Takabe; Hirokazu Tsukaya

2006-01-01

78

Survival and infectivity of Sarcoptes scabiei var. canis and var. hominis.  

PubMed

Sarcoptes scabiei var. canis served as a suitable model for the study of S. scabiei var. hominis survival. S. scabiei var. canis and var. hominis mites were found to survive off the host for 24 to 36 hours at room conditions (21 degrees C and 40% to 80% relative humidity [RH]), and the canine variety survived 19 days at 10 degrees C and 97% RH. Female mites survived decidedly longer than male mites at comparable conditions. Generally, higher RH values and lower temperatures favored survival, whereas higher temperature and lower RH led to early death. Most canine scabies mites that were held off the host for 36 hours at 75% RH and 22 degrees to 24 degrees C remained infective and penetrated when returned to the host. Live mites of the human variety that were recovered from bed linen slept on by infested patients would also penetrate a host after being held off a host for 96 hours in alternating 12-hour periods of room conditions and refrigeration. Penetration required less than 30 minutes for all life stages of both varieties, and it was accomplished by a mite secretion that dissolved the host tissue. Dislodged mites, particularly those in close proximity to the source, can be a likely source of infestation. PMID:6434601

Arlian, L G; Runyan, R A; Achar, S; Estes, S A

1984-08-01

79

Characterization of the effects of methylmercury on Caenorhabditis elegans  

SciTech Connect

The rising prevalence of methylmercury (MeHg) in seafood and in the global environment provides an impetus for delineating the mechanism of the toxicity of MeHg. Deleterious effects of MeHg have been widely observed in humans and in other mammals, the most striking of which occur in the nervous system. Here we test the model organism, Caenorhabditis elegans (C. elegans), for MeHg toxicity. The simple, well-defined anatomy of the C. elegans nervous system and its ready visualization with green fluorescent protein (GFP) markers facilitated our study of the effects of methylmercuric chloride (MeHgCl) on neural development. Although MeHgCl was lethal to C. elegans, induced a developmental delay, and decreased pharyngeal pumping, other traits including lifespan, brood size, swimming rate, and nervous system morphology were not obviously perturbed in animals that survived MeHgCl exposure. Despite the limited effects of MeHgCl on C. elegans development and behavior, intracellular mercury (Hg) concentrations ({<=} 3 ng Hg/mg protein) in MeHgCl-treated nematodes approached levels that are highly toxic to mammals. If MeHgCl reaches these concentrations throughout the animal, this finding indicates that C. elegans cells, particularly neurons, may be less sensitive to MeHgCl toxicity than mammalian cells. We propose, therefore, that C. elegans should be a useful model for discovering intrinsic mechanisms that confer resistance to MeHgCl exposure.

Helmcke, Kirsten J. [Pharmacology Department, Vanderbilt University Medical Center, Nashville, TN (United States); Syversen, Tore [Department of Neuromedicine, Norwegian University of Science and Technology, Trondheim (Norway); Miller, David M. [Department of Cell and Developmental Biology and Program in Neuroscience, Vanderbilt University Medical Center, Nashville, TN (United States); Aschner, Michael [Pharmacology Department, Vanderbilt University Medical Center, Nashville, TN (United States); Pediatrics Department, Vanderbilt University Medical Center, Nashville, TN (United States)], E-mail: Michael.Aschner@vanderbilt.edu

2009-10-15

80

Caenorhabditis elegans as a model for intracellular pathogen infection  

PubMed Central

Summary The genetically tractable nematode Caenorhabditis elegans is a convenient host for studies of pathogen infection. With the recent identification of two types of natural intracellular pathogens of C. elegans, this host now provides the opportunity to examine interactions and defence against intracellular pathogens in a whole-animal model for infection. C. elegans is the natural host for a genus of microsporidia, which comprise a phylum of fungal-related pathogens of widespread importance for agriculture and medicine. More recently, C. elegans has been shown to be a natural host for viruses related to the Nodaviridae family. Both microsporidian and viral pathogens infect the C. elegans intestine, which is composed of cells that share striking similarities to human intestinal epithelial cells. Because C. elegans nematodes are transparent, these infections provide a unique opportunity to visualize differentiated intestinal cells in vivo during the course of intracellular infection. Together, these two natural pathogens of C. elegans provide powerful systems in which to study microbial pathogenesis and host responses to intracellular infection. PMID:23617769

Balla, Keir M.; Troemel, Emily R.

2014-01-01

81

A database of Caenorhabditis elegans behavioral phenotypes.  

PubMed

Using low-cost automated tracking microscopes, we have generated a behavioral database for 305 Caenorhabditis elegans strains, including 76 mutants with no previously described phenotype. The growing database currently consists of 9,203 short videos segmented to extract behavior and morphology features, and these videos and feature data are available online for further analysis. The database also includes summary statistics for 702 measures with statistical comparisons to wild-type controls so that phenotypes can be identified and understood by users. PMID:23852451

Yemini, Eviatar; Jucikas, Tadas; Grundy, Laura J; Brown, André E X; Schafer, William R

2013-09-01

82

Longevity and stress in Caenorhabditis elegans  

PubMed Central

It has long been understood that many of the same manipulations that increase longevity in Caenorhabditis elegans also increase resistance to various acute stressors, and vice-versa; moreover these findings hold in more complex organisms as well. Nevertheless, the mechanistic relationship between these phenotypes remains unclear, and in many cases the overlap between stress resistance and longevity is inexact. Here we review the known connections between stress resistance and longevity, discuss instances in which these connections are absent, and summarize the theoretical explanations that have been posited for these phenomena. PMID:21937765

Zhou, Katherine I.; Pincus, Zachary; Slack, Frank J.

2011-01-01

83

Research Focus Malaria: a peek at the var variorum  

E-print Network

to multiple var gene products during one infection does not necessarily confer immunity to future malaria family for the first time often com- plain that its complexity is a nightmare. A new article by Barry et. This important work, combined with other recent articles on var global variation such as that by Kraemer et al

Hartl, Daniel L.

84

The robustness of identified VAR conclusions about money  

Microsoft Academic Search

This paper presents a new way to assess robustness of claims from identified VAR work. All possible identifications are checked for the one that is worst for the claim, subject to the restriction that the VAR produce reasonable impulse responses to shocks. The statistic on which the claim is based need not be identified; thus, one can assess claims in

Jon Faust

1998-01-01

85

Microsporidia Are Natural Intracellular Parasites of the Nematode Caenorhabditis elegans  

PubMed Central

For decades the soil nematode Caenorhabditis elegans has been an important model system for biology, but little is known about its natural ecology. Recently, C. elegans has become the focus of studies of innate immunity and several pathogens have been shown to cause lethal intestinal infections in C. elegans. However none of these pathogens has been shown to invade nematode intestinal cells, and no pathogen has been isolated from wild-caught C. elegans. Here we describe an intracellular pathogen isolated from wild-caught C. elegans that we show is a new species of microsporidia. Microsporidia comprise a large class of eukaryotic intracellular parasites that are medically and agriculturally important, but poorly understood. We show that microsporidian infection of the C. elegans intestine proceeds through distinct stages and is transmitted horizontally. Disruption of a conserved cytoskeletal structure in the intestine called the terminal web correlates with the release of microsporidian spores from infected cells, and appears to be part of a novel mechanism by which intracellular pathogens exit from infected cells. Unlike in bacterial intestinal infections, the p38 MAPK and insulin/insulin-like growth factor (IGF) signaling pathways do not appear to play substantial roles in resistance to microsporidian infection in C. elegans. We found microsporidia in multiple wild-caught isolates of Caenorhabditis nematodes from diverse geographic locations. These results indicate that microsporidia are common parasites of C. elegans in the wild. In addition, the interaction between C. elegans and its natural microsporidian parasites provides a system in which to dissect intracellular intestinal infection in vivo and insight into the diversity of pathogenic mechanisms used by intracellular microbes. PMID:19071962

Troemel, Emily R; Félix, Marie-Anne; Whiteman, Noah K; Barrière, Antoine; Ausubel, Frederick M

2008-01-01

86

Macrorestriction Analysis of Caenorhabditis Elegans Genomic DNA  

PubMed Central

The usefulness of genomic physical maps is greatly enhanced by linkage of the physical map with the genetic map. We describe a ``macrorestriction mapping'' procedure for Caenorhabditis elegans that we have applied to this endeavor. High molecular weight, genomic DNA is digested with infrequently cutting restriction enzymes and size-fractionated by pulsed field gel electrophoresis. Southern blots of the gels are probed with clones from the C. elegans physical map. This procedure allows the construction of restriction maps covering several hundred kilobases and the detection of polymorphic restriction fragments using probes that map several hundred kilobases away. We describe several applications of this technique. (1) We determined that the amount of DNA in a previously uncloned region is <220 kb. (2) We mapped the mes-1 gene to a cosmid, by detecting polymorphic restriction fragments associated with a deletion allele of the gene. The 25-kb deletion was initially detected using as a probe sequences located ~400 kb away from the gene. (3) We mapped the molecular endpoint of the deficiency hDf6, and determined that three spontaneously derived duplications in the unc-38-dpy-5 region have very complex molecular structures, containing internal rearrangements and deletions. PMID:8889524

Browning, H.; Berkowitz, L.; Madej, C.; Paulsen, J. E.; Zolan, M. E.; Strome, S.

1996-01-01

87

Nucleologenesis in the Caenorhabditis elegans Embryo  

PubMed Central

In the Caenorhabditis elegans nematode, the oocyte nucleolus disappears prior to fertilization. We have now investigated the re-formation of the nucleolus in the early embryo of this model organism by immunostaining for fibrillarin and DAO-5, a putative NOLC1/Nopp140 homolog involved in ribosome assembly. We find that labeled nucleoli first appear in somatic cells at around the 8-cell stage, at a time when transcription of the embryonic genome begins. Quantitative analysis of radial positioning showed the nucleolus to be localized at the nuclear periphery in a majority of early embryonic nuclei. At the ultrastructural level, the embryonic nucleolus appears to be composed of a relatively homogenous core surrounded by a crescent-shaped granular structure. Prior to embryonic genome activation, fibrillarin and DAO-5 staining is seen in numerous small nucleoplasmic foci. This staining pattern persists in the germline up to the ?100-cell stage, until the P4 germ cell divides to give rise to the Z2/Z3 primordial germ cells and embryonic transcription is activated in this lineage. In the ncl-1 mutant, which is characterized by increased transcription of rDNA, DAO-5-labeled nucleoli are already present at the 2-cell stage. Our results suggest a link between the activation of transcription and the initial formation of nucleoli in the C. elegans embryo. PMID:22768349

Kor?eková, Darina; Gombitová, Adriána; Raška, Ivan; Cmarko, Dušan; Lanctôt, Christian

2012-01-01

88

Widespread Genomic Incompatibilities in Caenorhabditis elegans  

PubMed Central

In the Bateson-Dobzhansky-Muller (BDM) model of speciation, incompatibilities emerge from the deleterious interactions between alleles that are neutral or advantageous in the original genetic backgrounds, i.e., negative epistatic effects. Within species such interactions are responsible for outbreeding depression and F2 (hybrid) breakdown. We sought to identify BDM incompatibilities in the nematode Caenorhabditis elegans by looking for genomic regions that disrupt egg laying; a complex, highly regulated, and coordinated phenotype. Investigation of introgression lines and recombinant inbred lines derived from the isolates CB4856 and N2 uncovered multiple incompatibility quantitative trait loci (QTL). These QTL produce a synthetic egg-laying defective phenotype not seen in CB4856 and N2 nor in other wild isolates. For two of the QTL regions, results are inconsistent with a model of pairwise interaction between two loci, suggesting that the incompatibilities are a consequence of complex interactions between multiple loci. Analysis of additional life history traits indicates that the QTL regions identified in these screens are associated with effects on other traits such as lifespan and reproduction, suggesting that the incompatibilities are likely to be deleterious. Taken together, these results indicate that numerous BDM incompatibilities that could contribute to reproductive isolation can be detected and mapped within C. elegans. PMID:25128438

Snoek, L. Basten; Orbidans, Helen E.; Stastna, Jana J.; Aartse, Aafke; Rodriguez, Miriam; Riksen, Joost A.G.; Kammenga, Jan E.; Harvey, Simon C.

2014-01-01

89

PCH-2 regulates Caenorhabditis elegans lifespan.  

PubMed

Components or downstream targets of many signaling pathways such as Insulin/IGF-1 and TOR, as well as genes involved in cellular metabolism and bioenergetics can extend worm lifespan 20% or more. The C. elegans gene pch-2 and its homologs, including TRIP13 in humans, have been studied for their functions in cell mitosis and meiosis, but have never been implicated in lifespan regulation. Here we show that over-expression of TRIP13 in human fibroblasts confers resistance to environmental stressors such as UV radiation and oxidative stress. Furthermore, pch-2 overexpression in C. elegans extends worm lifespan, and enhances worm survival in response to various stressors. Conversely, reducing pch-2 expression with RNAi shortens worm lifespan. Additional genetic epistasis analysis indicates that the molecular mechanism of pch-2 in worm longevity is tied to functions of the sirtuin family, implying that pch-2 is another chromatin regulator for worm longevity. These findings suggest a novel function of the pch-2 gene involved in lifespan determination. PMID:25635513

Qian, Hong; Xu, Xiangru; Niklason, Laura E

2015-01-01

90

Widespread genomic incompatibilities in Caenorhabditis elegans.  

PubMed

In the Bateson-Dobzhansky-Muller (BDM) model of speciation, incompatibilities emerge from the deleterious interactions between alleles that are neutral or advantageous in the original genetic backgrounds, i.e., negative epistatic effects. Within species such interactions are responsible for outbreeding depression and F2 (hybrid) breakdown. We sought to identify BDM incompatibilities in the nematode Caenorhabditis elegans by looking for genomic regions that disrupt egg laying; a complex, highly regulated, and coordinated phenotype. Investigation of introgression lines and recombinant inbred lines derived from the isolates CB4856 and N2 uncovered multiple incompatibility quantitative trait loci (QTL). These QTL produce a synthetic egg-laying defective phenotype not seen in CB4856 and N2 nor in other wild isolates. For two of the QTL regions, results are inconsistent with a model of pairwise interaction between two loci, suggesting that the incompatibilities are a consequence of complex interactions between multiple loci. Analysis of additional life history traits indicates that the QTL regions identified in these screens are associated with effects on other traits such as lifespan and reproduction, suggesting that the incompatibilities are likely to be deleterious. Taken together, these results indicate that numerous BDM incompatibilities that could contribute to reproductive isolation can be detected and mapped within C. elegans. PMID:25128438

Snoek, L Basten; Orbidans, Helen E; Stastna, Jana J; Aartse, Aafke; Rodriguez, Miriam; Riksen, Joost A G; Kammenga, Jan E; Harvey, Simon C

2014-10-01

91

A uniform genetic nomenclature for the nematode Caenorhabditis elegans  

Microsoft Academic Search

A uniform system of genetic nomenclature for the nematode Caenorhabditis elegans is described. Convenient ways are specified to designate genes, mutations and strains, and to attempt to avoid name duplications.

H. Robert Horvitz; Sydney Brenner; Jonathan Hodgkin; Robert K. Herman

1979-01-01

92

The Perfect C. elegans Project: An Initial Report Hiroaki Kitano  

E-print Network

, and the initial results of the project. 1 Introduction When Sydney Brenner proposed the investigating C. elegans to the Medical Research Council, he chose it because it was the simplest of all differentiated organisms [Brenner

Luke, Sean

93

Exploring functional structure through system organization: Caenorhabditis elegans neuronal network  

E-print Network

Exploring functional structure through system organization: Caenorhabditis elegans neuronal network, systemic organization, modular structure, functional circuit #12; Hyeok Jung Kang1 , Myung-Kyu Choi2, Junho Lee2 , Namkyoo Park*1 *nkpark@snu.ac.kr 1 Photonic Systems

Park, Namkyoo

94

Caenorhabditis elegans: An Emerging Model in Biomedical and Environmental Toxicology  

PubMed Central

The nematode Caenorhabditis elegans has emerged as an important animal model in various fields including neurobiology, developmental biology, and genetics. Characteristics of this animal model that have contributed to its success include its genetic manipulability, invariant and fully described developmental program, well-characterized genome, ease of maintenance, short and prolific life cycle, and small body size. These same features have led to an increasing use of C. elegans in toxicology, both for mechanistic studies and high-throughput screening approaches. We describe some of the research that has been carried out in the areas of neurotoxicology, genetic toxicology, and environmental toxicology, as well as high-throughput experiments with C. elegans including genome-wide screening for molecular targets of toxicity and rapid toxicity assessment for new chemicals. We argue for an increased role for C. elegans in complementing other model systems in toxicological research. PMID:18566021

Leung, Maxwell C. K.; Williams, Phillip L.; Benedetto, Alexandre; Au, Catherine; Helmcke, Kirsten J.; Aschner, Michael; Meyer, Joel N.

2008-01-01

95

Bacterial attraction and quorum sensing inhibition in Caenorhabditis elegans exudates  

Technology Transfer Automated Retrieval System (TEKTRAN)

Caenorhabditis elegans, a bacterivorous soil nematode, lives in a complex environment that requires chemical communication for mating, monitoring population density, recognition of food, avoidance of pathogenic microbes, and other essential ecological functions. Despite being one of the best-studied...

96

Natural and Unanticipated Modifiers of RNAi Activity in Caenorhabditis elegans  

E-print Network

in isogenic strains of Caenorhabditis elegans. In so doing, we uncovered a mutation that arose de novo in an existing strain, which initially frustrated our phenotypic analysis. We also report experimental, environmental, and genetic conditions that can...

Asad, Nadeem; Yih Aw, Wen; Timmons, Lisa

2012-11-28

97

Formation, regulation and evolution of Caenorhabditis elegans 3'UTRs  

E-print Network

Post-transcriptional gene regulation frequently occurs through elements in mRNA 3? untranslated regions (UTRs)1, 2. Although crucial roles for 3?UTR-mediated gene regulation have been found in Caenorhabditis elegans3, 4, ...

Jan, Calvin H.

98

[Chemical constituents of Camellia sinensis var. assamica].  

PubMed

To study the chemical constituents of Camellia sinensis var. assamica. The compounds were isolated by NKA Macroporous resin silica gel, Sephadex LH-20, RP-C18 column chromatographies and semi-preparative HPLC,and their structures were elucidated by physicochemical properties and spectral analysis. Thirteen compounds were isolated and identified as caffeine (1), theobromine (2), gallic acid (3), (+)-catechin (4), ampelopsin (5), (-)-epicatechin (6), (-)-epiafzelechin (7), (-)-epicatechin-3-O-gallate (8), (-)-epiafzelechin-3-O-gallate (9) , (+)-catechin-3-O-gallate (10) , (+)-afzelechin-3-O-gallate (11), quemefin-3-O-alpha-L-arabinopyranosid (12), and (-)-epicatechin-3-O-p-hydroxybenzoate (13). Compounds 2, 5, 10-13 were isolated from this plant for the first time, and compound 11 is a new natural product. PMID:23944074

Zhu, Hong-Bo; Li, Bao-Min; Liu, Chao; Chen, Ruo-Yun

2013-05-01

99

Antifungal terpenoids from Hyalis argentea var. latisquama.  

PubMed

A detailed chemical study of the aerial parts and rhizomes of Hyalis argentea var. latisquama yielded a variety of sesqui- and diterpenes. In total, 26 compounds were isolated and identified, of which four are new, namely, two ent-kaurenes (1 and 2), a diterpene lactone (3), and a lindenanolide (4). The previously reported compounds included a series of lindenanolides, guaianolides, elemanolides, and additional diterpenes. The antifungal activity of the isolated compounds was tested against Cryptococcus neoformans and Candida albicans. Among the isolated compounds, the lindenanolides were the only structural class that showed strong antifungal activity, and onoseriolide acetate (5) was the most active. On the other hand, the isolated guaianolides were only moderately active, while the diterpenes did not show significant antifungal activity. PMID:25026191

Fernández, Lucía R; Butassi, Estefanía; Svetaz, Laura; Zacchino, Susana A; Palermo, Jorge A; Sánchez, Marianela

2014-07-25

100

1D-VAR Retrieval Using Superchannels  

NASA Technical Reports Server (NTRS)

Since modern ultra-spectral remote sensors have thousands of channels, it is difficult to include all of them in a 1D-var retrieval system. We will describe a physical inversion algorithm, which includes all available channels for the atmospheric temperature, moisture, cloud, and surface parameter retrievals. Both the forward model and the inversion algorithm compress the channel radiances into super channels. These super channels are obtained by projecting the radiance spectra onto a set of pre-calculated eigenvectors. The forward model provides both super channel properties and jacobian in EOF space directly. For ultra-spectral sensors such as Infrared Atmospheric Sounding Interferometer (IASI) and the NPOESS Airborne Sounder Testbed Interferometer (NAST), a compression ratio of more than 80 can be achieved, leading to a significant reduction in computations involved in an inversion process. Results will be shown applying the algorithm to real IASI and NAST data.

Liu, Xu; Zhou, Daniel; Larar, Allen; Smith, William L.; Schluessel, Peter; Mango, Stephen; SaintGermain, Karen

2008-01-01

101

The Geometry of Locomotive Behavioral States in C. elegans  

PubMed Central

We develop a new hidden Markov model-based method to analyze C elegans locomotive behavior and use this method to quantitatively characterize behavioral states. In agreement with previous work, we find states corresponding to roaming, dwelling, and quiescence. However, we also find evidence for a continuum of intermediate states. We suggest that roaming, dwelling, and quiescence may best be thought of as extremes which, mixed in any proportion, define the locomotive repertoire of C elegans foraging and feeding behavior. PMID:23555813

Bjorness, Theresa; Greene, Robert; You, Young-Jai

2013-01-01

102

The Genetics of Development and Behavior in Caenorhabditis elegans  

PubMed Central

The current genetic research on Caenorhabditis elegans and the application of genetic techniques to the analysis of development and behavior in this animal are reviewed. Some aspects of the work are emphasized more than others and this inevitably reflects the author's own interests and prejudices. An effort was made to point out the advantages that C. elegans offers for certain types of investigations and to point out, in general terms, the relevance of this work to other areas of biological research. PMID:19305805

Riddle, Donald L.

1978-01-01

103

An Extensive Class of Small RNAs in Caenorhabditis elegans  

Microsoft Academic Search

The lin-4 and let-7 antisense RNAs are temporal regulators that control the timing of developmental events in Caenorhabditis elegans by inhibiting translation of target mRNAs. let-7 RNA is conserved among bilaterian animals, suggesting that this class of small RNAs [microRNAs (miRNAs)] is evolutionarily ancient. Using bioinformatics and cDNA cloning, we found 15 new miRNA genes in C. elegans. Several of

Rosalind C. Lee; Victor Ambros

2001-01-01

104

Transposition of Tc1 in the Nematode Caenorhabditis elegans  

Microsoft Academic Search

We have identified a strain of Caenorhabditis elegans in which the transposable element Tc1 is genetically active. Most spontaneous mutations affecting the unc-54 myosin heavy chain gene of C. elegans variety Bergerac are due to insertions of Tc1 within unc-54. The Bergerac genome contains an unusually high number of Tc1 elements, but this is not responsible for transpositional activity. Another

David Eide; Philip Anderson

1985-01-01

105

Japanese studies on neural circuits and behavior of Caenorhabditis elegans  

PubMed Central

The nematode Caenorhabditis elegans is an ideal organism for studying neural plasticity and animal behaviors. A total of 302 neurons of a C. elegans hermaphrodite have been classified into 118 neuronal groups. This simple neural circuit provides a solid basis for understanding the mechanisms of the brains of higher animals, including humans. Recent studies that employ modern imaging and manipulation techniques enable researchers to study the dynamic properties of nervous systems with great precision. Behavioral and molecular genetic analyses of this tiny animal have contributed greatly to the advancement of neural circuit research. Here, we will review the recent studies on the neural circuits of C. elegans that have been conducted in Japan. Several laboratories have established unique and clever methods to study the underlying neuronal substrates of behavioral regulation in C. elegans. The technological advances applied to studies of C. elegans have allowed new approaches for the studies of complex neural systems. Through reviewing the studies on the neuronal circuits of C. elegans in Japan, we will analyze and discuss the directions of neural circuit studies. PMID:24348340

Sasakura, Hiroyuki; Tsukada, Yuki; Takagi, Shin; Mori, Ikue

2013-01-01

106

Mainstreaming Caenorhabditis elegans in experimental evolution  

PubMed Central

Experimental evolution provides a powerful manipulative tool for probing evolutionary process and mechanism. As this approach to hypothesis testing has taken purchase in biology, so too has the number of experimental systems that use it, each with its own unique strengths and weaknesses. The depth of biological knowledge about Caenorhabditis nematodes, combined with their laboratory tractability, positions them well for exploiting experimental evolution in animal systems to understand deep questions in evolution and ecology, as well as in molecular genetics and systems biology. To date, Caenorhabditis elegans and related species have proved themselves in experimental evolution studies of the process of mutation, host–pathogen coevolution, mating system evolution and life-history theory. Yet these organisms are not broadly recognized for their utility for evolution experiments and remain underexploited. Here, we outline this experimental evolution work undertaken so far in Caenorhabditis, detail simple methodological tricks that can be exploited and identify research areas that are ripe for future discovery. PMID:24430852

Gray, Jeremy C.; Cutter, Asher D.

2014-01-01

107

Novel insertion mutation in Caenorhabditis elegans.  

PubMed

The mutation e1662 is an allele of the Caenorhabditis elegans unc-54 gene induced with the difunctional alkylating agent 1,2,7,8-diepoxyoctane. unc-54 encodes the major myosin heavy chain isozyme of body wall muscle cells. Filter-transfer hybridization and DNA sequence analysis show that e1662 is an insertion of 288 base pairs of DNA within unc-54. The inserted DNA is identical to a 288-base pair region of unc-54 located ca. 600 base pairs from the insertion site. Thus, e1662 is a displaced duplication. A 14-base pair sequence located at one end of the duplicated segment is found adjacent to the site of insertion. These homologous sequences are juxtaposed head-to-tail by the insertion event. e1662 thus contains a tandem direct repeat extending across one of its junctions. PMID:3982411

Eide, D J; Anderson, P

1985-01-01

108

Ultrafast endocytosis at Caenorhabditis elegans neuromuscular junctions  

PubMed Central

Synaptic vesicles can be released at extremely high rates, which places an extraordinary demand on the recycling machinery. Previous ultrastructural studies of vesicle recycling were conducted in dissected preparations using an intense stimulation to maximize the probability of release. Here, a single light stimulus was applied to motor neurons in intact Caenorhabditis elegans nematodes expressing channelrhodopsin, and the animals rapidly frozen. We found that docked vesicles fuse along a broad active zone in response to a single stimulus, and are replenished with a time constant of about 2 s. Endocytosis occurs within 50 ms adjacent to the dense projection and after 1 s adjacent to adherens junctions. These studies suggest that synaptic vesicle endocytosis may occur on a millisecond time scale following a single physiological stimulus in the intact nervous system and is unlikely to conform to current models of endocytosis. DOI: http://dx.doi.org/10.7554/eLife.00723.001 PMID:24015355

Watanabe, Shigeki; Liu, Qiang; Davis, M Wayne; Hollopeter, Gunther; Thomas, Nikita; Jorgensen, Nels B; Jorgensen, Erik M

2013-01-01

109

Dynamic patterning of maternal mRNAs in the Early C. elegans embryo  

E-print Network

Asymmetric segregation of maternally-encoded proteins is essential to cell fate determination during early cell divisions of the Caenorhabditis elegans (C. elegans) embryo, but little is known about the patterning of ...

Li, Jialing, Ph. D. Massachusetts Institute of Technology

2012-01-01

110

Caenorhabditis elegans NPR-1–mediated behaviors are suppressed in the presence of mucoid bacteria  

E-print Network

Caenorhabditis elegans exhibits a diverse range of behaviors in response to bacteria. The presence of bacterial food influences C. elegans aerotaxis, aggregation, locomotion, and pathogen avoidance behaviors through the ...

Reddy, Kirthi C.

111

Spread and transmission of bacterial pathogens in experimental nematode populations of Caenorhabditis elegans.  

E-print Network

. Evolution of host innate 498 defence: insights from Caenorhabditis elegans and primitive invertebrates. 499 Nat. Rev. Immunol. 10:47–58. 500 3. Ewbank JJ. 2002. Tackling both sides of the host-pathogen equation with 501 Caenorhabditis elegans. Microbes...

Diaz, S. Anaid; Restif, Olivier

2014-06-22

112

CHARACTERIZATION OF THE PARASPORAL INCLUSION OF BACILLUS THURINGIENSIS VAR. KYUSHUENSIS  

EPA Science Inventory

Bacillus thuringiensis var. kyushuensis synthesizes an irregularly shaped parasporal inclusion during sporulation. lectron microscopy revealed that the inclusions are composed of a relatively homogeneous appearing center surrounded by a thick, electron dense coating. urified incl...

113

Prenylated Phloroglucinol Derivatives from Hypericum perforatum var. angustifolium.  

PubMed

Two new prenylated phloroglucinol derivatives and 15 known compounds were isolated from the aerial parts of Hypericum perforatum var. angustifolium. Their structures were determined on the basis of spectroscopic evidence. PMID:18670119

Hashida, Chika; Tanaka, Naonobu; Kashiwada, Yoshiki; Ogawa, Makoto; Takaishi, Yoshihisa

2008-08-01

114

Pseudomonas aeruginosa Killing of Caenorhabditis elegans Used to Identify P. aeruginosa Virulence Factors  

Microsoft Academic Search

We reported recently that the human opportunistic pathogen Pseudomonas aeruginosa strain PA14 kills Caenorhabditis elegans and that many P. aeruginosa virulence factors (genes) required for maximum virulence in mouse pathogenicity are also required for maximum killing of C. elegans. Here we report that among eight P. aeruginosa PA14 TnphoA mutants isolated that exhibited reduced killing of C. elegans, at least

Man-Wah Tan; Laurence G. Rahme; Jeffrey A. Sternberg; Ronald G. Tompkins; Frederick M. Ausubel

1999-01-01

115

http://C.elegans: mining the functional genomic landscape Stuart K. Kim  

E-print Network

or genome-wide expression studies)3,4 . The modern field of C. elegans began with a publication by Sydney Brenner less than thirty years ago5 , and so C. elegans has a shorter research history than that of humans or Drosophila. Since Brenner's first paper, only 1877 C. elegans genes (9% of the genome) have been examined

Kim, Stuart

116

Cytochrome b Phylogeny Does Not Match Subspecific Classification in the Western Terrestrial Garter Snake, Thamnophis elegans  

Microsoft Academic Search

We sequenced a 307-bp fragment of the mitochondrial cytochrome b gene from 42 individuals representing 14 populations of the western terrestrial garter snake, Thamnophis elegans. Current taxonomy recognizes either five or six subspecies of T. elegans based on color and scale morphology, but all agree on three major geograph- ic races (T. e. elegans, terrestris, and vagrans). Although the cytochrome

Anne M. Bronikowski; Stevan J. Arnold; J. D. McEachran

2001-01-01

117

Life cycle of Sarcoptes scabiei var. canis.  

PubMed

The life cycle of Sarcoptes scabiei var. canis was systematically investigated in vivo. The life cycle of females and males consisted of an egg, larva, protonymph, and a tritonymph that gave rise to an adult. Development from egg to adult required 10.06-13.16 days for the male and 9.93-13.03 days for the female. Egg incubation times were greater than 50.1 to less than 52.97 hr. Larval duration was between 3.22 and 4.20 days. The durations of protonymphal stages that were destined to become females and males were greater than 2.40 to less than 3.40 days and greater than 2.33 to less than 3.33 days, respectively. Tritonymphs destined to become females and males molted in greater than 2.22 to less than 3.22 days and greater than 2.42 to less than 3.42 days, respectively. During development, all life stages frequently left their burrows and wandered on the skin surface. PMID:3132547

Arlian, L G; Vyszenski-Moher, D L

1988-06-01

118

Genetic dissection of late-life fertility in Caenorhabditis elegans.  

PubMed

The large post-reproductive life span reported for the free-living hermaphroditic nematode, Caenorhabditis elegans, which lives for about 10 days after its 5-day period of self-reproduction, seems at odds with evolutionary theory. Species with long post-reproductive life spans such as mammals are sometimes explained by a need for parental care or transfer of information. This does not seem a suitable explanation for C elegans. Previous reports have shown that C elegans can regain fertility when mated after the self-fertile period but did not report the functional limits. Here, we report the functional life span of the C elegans germ line when mating with males. We show that C elegans can regain fertility late in life (significantly later than in previous reports) and that the end of this period corresponds quite well to its 3-week total life span. Genetic analysis reveals that late-life fertility is controlled by conserved pathways involved with aging and dietary restriction. PMID:21622982

Mendenhall, Alexander R; Wu, Deqing; Park, Sang-Kyu; Cypser, James R; Tedesco, Patricia M; Link, Christopher D; Phillips, Patrick C; Johnson, Thomas E

2011-08-01

119

Neural circuits mediate electrosensory behavior in Caenorhabditis elegans.  

PubMed

The nematode Caenorhabditis elegans deliberately crawls toward the negative pole in an electric field. By quantifying the movements of individual worms navigating electric fields, we show that C. elegans prefers to crawl at specific angles to the direction of the electric field in persistent periods of forward movement and that the preferred angle is proportional to field strength. C. elegans reorients itself in response to time-varying electric fields by using sudden turns and reversals, standard reorientation maneuvers that C. elegans uses during other modes of motile behavior. Mutation or laser ablation that disrupts the structure and function of amphid sensory neurons also disrupts electrosensory behavior. By imaging intracellular calcium dynamics among the amphid sensory neurons of immobilized worms, we show that specific amphid sensory neurons are sensitive to the direction and strength of electric fields. We extend our analysis to the motor level by showing that specific interneurons affect the utilization of sudden turns and reversals during electrosensory steering. Thus, electrosensory behavior may be used as a model system for understanding how sensory inputs are transformed into motor outputs by the C. elegans nervous system. PMID:17626220

Gabel, Christopher V; Gabel, Harrison; Pavlichin, Dmitri; Kao, Albert; Clark, Damon A; Samuel, Aravinthan D T

2007-07-11

120

Caenorhabditis elegans: A Simple Nematode Infection Model for Penicillium marneffei  

PubMed Central

Penicillium marneffei, one of the most important thermal dimorphic fungi, is a severe threat to the life of immunocompromised patients. However, the pathogenic mechanisms of P. marneffei remain largely unknown. In this work, we developed a model host by using nematode Caenorhabditis elegans to investigate the virulence of P. marneffei. Using two P. marneffei clinical isolate strains 570 and 486, we revealed that in both liquid and solid media, the ingestion of live P. marneffei was lethal to C. elegans (P<0.001). Meanwhile, our results showed that the strain 570, which can produce red pigment, had stronger pathogenicity in C. elegans than the strain 486, which can’t produce red pigment (P<0.001). Microscopy showed the formation of red pigment and hyphae within C. elegans after incubation with P. marneffei for 4 h, which are supposed to be two contributors in nematodes killing. In addition, we used C. elegans as an in vivo model to evaluate different antifungal agents against P. marneffei, and found that antifungal agents including amphotericin B, terbinafine, fluconazole, itraconazole and voriconazole successfully prolonged the survival of nematodesinfected by P. marneffei. Overall, this alternative model host can provide us an easy tool to study the virulence of P. marneffei and screen antifungal agents. PMID:25268236

Huang, Xiaowen; Li, Dedong; Xi, Liyan; Mylonakis, Eleftherios

2014-01-01

121

Formation and Regulation of Adaptive Response in Nematode Caenorhabditis elegans  

PubMed Central

All organisms respond to environmental stresses (e.g., heavy metal, heat, UV irradiation, hyperoxia, food limitation, etc.) with coordinated adjustments in order to deal with the consequences and/or injuries caused by the severe stress. The nematode Caenorhabditis elegans often exerts adaptive responses if preconditioned with low concentrations of agents or stressor. In C. elegans, three types of adaptive responses can be formed: hormesis, cross-adaptation, and dietary restriction. Several factors influence the formation of adaptive responses in nematodes, and some mechanisms can explain their response formation. In particular, antioxidation system, heat-shock proteins, metallothioneins, glutathione, signaling transduction, and metabolic signals may play important roles in regulating the formation of adaptive responses. In this paper, we summarize the published evidence demonstrating that several types of adaptive responses have converged in C. elegans and discussed some possible alternative theories explaining the adaptive response control. PMID:22997543

Zhao, Y.-L.; Wang, D.-Y.

2012-01-01

122

Femtosecond laser dissection in C. elegans neural circuits  

NASA Astrophysics Data System (ADS)

The nematode C. elegans, a millimeter-long roundworm, is a well-established model organism for studies of neural development and behavior, however physiological methods to manipulate and monitor the activity of its neural network have lagged behind the development of powerful methods in genetics and molecular biology. The small size and transparency of C. elegans make the worm an ideal test-bed for the development of physiological methods derived from optics and microscopy. We present the development and application of a new physiological tool: femtosecond laser dissection, which allows us to selectively ablate segments of individual neural fibers within live C. elegans. Femtosecond laser dissection provides a scalpel with submicrometer resolution, and we discuss its application in studies of neural growth, regenerative growth, and the neural basis of behavior.

Samuel, Aravinthan D. T.; Chung, Samuel H.; Clark, Damon A.; Gabel, Christopher V.; Chang, Chieh; Murthy, Venkatesh; Mazur, Eric

2006-02-01

123

Proprioceptive coupling within motor neurons drives C. elegans forward locomotion  

PubMed Central

Summary Locomotion requires coordinated motor activity throughout an animal’s body. In both vertebrates and invertebrates, chains of coupled Central Pattern Generators (CPGs) are commonly evoked to explain local rhythmic behaviors. In C. elegans, we report that proprioception within the motor circuit is responsible for propagating and coordinating rhythmic undulatory waves from head to tail during forward movement. Proprioceptive coupling between adjacent body regions transduces rhythmic movement initiated near the head into bending waves driven along the body by a chain of reflexes. Using optogenetics and calcium imaging to manipulate and monitor motor circuit activity of moving C. elegans held in microfluidic devices, we found that the B-type cholinergic motor neurons transduce the proprioceptive signal. In C. elegans, a sensorimotor feedback loop operating within a specific type of motor neuron both drives and organizes body movement. PMID:23177960

Wen, Quan; Po, Michelle; Hulme, Elizabeth; Chen, Sway; Liu, Xinyu; Kwok, Sen Wai; Gershow, Marc; Leifer, Andrew M; Butler, Victoria; Fang-Yen, Christopher; Kawano, Taizo; Schafer, William R; Whitesides, George

2012-01-01

124

Insights and challenges in using C. elegans for investigation of fat metabolism.  

PubMed

Abstract C. elegans provides a genetically tractable system for deciphering the homeostatic mechanisms that underlie fat regulation in intact organisms. Here, we provide an overview of the recent advances in the C. elegans fat field with particular attention to studies of C. elegans lipid droplets, the complex links between lipases, autophagy, and lifespan, and analyses of key transcriptional regulatory mechanisms that coordinate lipid homeostasis. These studies demonstrate the ancient origins of mammalian and C. elegans fat regulatory pathways and highlight how C. elegans is being used to identify and analyze novel lipid pathways that are then shown to function similarly in mammals. Despite its many advantages, study of fat regulation in C. elegans is currently faced with a number of conceptual and methodological challenges. We critically evaluate some of the assumptions in the field and highlight issues that we believe should be taken into consideration when interpreting lipid content data in C. elegans. PMID:25228063

Lemieux, George A; Ashrafi, Kaveh

2014-09-17

125

Effect of vitamin D3 on lifespan in Caenorhabditis elegans.  

PubMed

Vitamin D is an essential micronutrient, necessary for human health. To determine if Caenorhabditis elegans (C. elegans) could function as an effective model to study the mechanisms of action of vitamin D, we asked if vitamin D3 affects C. elegans lifespan. Multiple factors positively impact lifespan in this system including dietary restriction and vitamin E. In addition, the C. elegans DAF-12 nuclear hormone receptor is homologous to the vitamin D receptor in humans and is therefore a candidate for a functional vitamin D receptor. It was hypothesized that vitamin D3 supplementation would increase the lifespan of C. elegans in a DAF-12-dependent manner. Dose-response curves were completed, and results indicate that exposure to 1,000 µg/ml vitamin D3 significantly increased the lifespan of wild-type worms by up to 39% (p<0.001). The daf-12 mutants exposed to 1,000 µg/ml vitamin D3 lived significantly longer than daf-12 controls exposed to 0 µg/ml (p<0.001), but among worms exposed to 1,000 µg/ml vitamin D3, wild type lived significantly longer than daf-12 (p<0.01). The data suggest that vitamin D3 can interact with multiple receptors, possibly implicating the NHR family of nuclear hormone receptors related to DAF-12. This research is the first to our knowledge to utilize C. elegans as a model to study the impact of vitamin D3 on longevity and supports the use of this model system to increase our understanding of vitamin D function at the cellular level, its role in cellular health, and its potential medicinal utility in humans. PMID:24304198

Messing, Jennifer A; Heuberger, Roschelle; Schisa, Jennifer A

2013-12-01

126

Biochemical Analysis of Caenorhabditis elegans Surface Mutants  

PubMed Central

A collection of Caenorhabditis elegans mutants that show ectopic surface lectin binding (Srf mutants) was analyzed to determine the biochemical basis for this phenotype. This analysis involved selective removal or labeling of surface components, specific labeling of surface glycans, and fractionation of total protein with subsequent detection of wheat germ agglutinin (WGA) binding proteins. Wild-type and mutant nematodes showed no differences in their profiles of extractable surface glycoproteins or total WGA-binding proteins, suggesting that the ectopic lectin binding does not result from the novel expression of surface glycans. Instead, these results support a model in which ectopic lectin binding results from an unmasking of glycosylated components present in the insoluble cuticle matrix of wild-type animals. To explain the multiple internal defects found in some surface mutants, we propose that these mutants have a basic defect in protein processing. This defect would interfere with the expression of the postulated masking protein(s), as well as other proteins required for normal development. PMID:19274162

Silverman, Michael A.; Blaxter, Mark L.; Link, Christopher D.

1997-01-01

127

Caenorhabditis elegans vulval cell fate patterning  

NASA Astrophysics Data System (ADS)

The spatial patterning of three cell fates in a row of competent cells is exemplified by vulva development in the nematode Caenorhabditis elegans. The intercellular signaling network that underlies fate specification is well understood, yet quantitative aspects remain to be elucidated. Quantitative models of the network allow us to test the effect of parameter variation on the cell fate pattern output. Among the parameter sets that allow us to reach the wild-type pattern, two general developmental patterning mechanisms of the three fates can be found: sequential inductions and morphogen-based induction, the former being more robust to parameter variation. Experimentally, the vulval cell fate pattern is robust to stochastic and environmental challenges, and minor variants can be detected. The exception is the fate of the anterior cell, P3.p, which is sensitive to stochastic variation and spontaneous mutation, and is also evolving the fastest. Other vulval precursor cell fates can be affected by mutation, yet little natural variation can be found, suggesting stabilizing selection. Despite this fate pattern conservation, different Caenorhabditis species respond differently to perturbations of the system. In the quantitative models, different parameter sets can reconstitute their response to perturbation, suggesting that network variation among Caenorhabditis species may be quantitative. Network rewiring likely occurred at longer evolutionary scales.

Félix, Marie-Anne

2012-08-01

128

Phenanthrene Bioaccumulation in the Nematode Caenorhabditis elegans.  

PubMed

The contribution of food to the bioaccumulation of xenobiotics and hence toxicity is still an ambiguous issue. It is becoming more and more evident that universal statements cannot be made, but that the relative contribution of food-associated xenobiotics in bioaccumulation depends on species, substance, and environmental conditions. Yet, small-sized benthic or soil animals such as nematodes have largely been disregarded so far. Bioaccumulation of the polycyclic aromatic hydrocarbon phenanthrene in the absence and presence of bacterial food was measured in the nematode Caenorhabditis elegans. Elimination of phenanthrene in the nematodes was biphasic, suggesting that there was a slowly exchanging pool within the nematodes or that biotransformation of phenanthrene took place. Even with food present, dissolved phenanthrene was still the major contributor to bioaccumulated compound in nematode tissues, whereas the diet only contributed about 9%. Toxicokinetic parameters in the treatment without food were different from the ones of the treatment with bacteria, possibly because nematodes depleted their lipid reserves during starvation. PMID:25607770

Spann, Nicole; Goedkoop, Willem; Traunspurger, Walter

2015-02-01

129

Structures of spontaneous deletions in Caenorhabditis elegans.  

PubMed

We have investigated the structural features of spontaneous deletions in Caenorhabditis elegans. We cloned and sequenced the junctions of 16 spontaneous deletions affecting the unc-54 myosin heavy-chain gene and compared their sequences with those of the wild type. We analyzed these sequences in an attempt to identify structural features of the gene that are consistently involved in the spontaneous deletion process. Most deletions (15 of 16) removed a single contiguous region of DNA, with no nucleotides inserted or rearranged at the deletion junctions; one deletion was more complex. unc-54 deletions were small, averaging 600 base pairs in length, and were randomly distributed throughout the gene. Unlike deletions that occur in Escherichia coli, spontaneous unc-54 deletions did not contain statistically significant direct or inverted repeats at or near their termini. Except for their small average size, we have not identified any distinguishing features of their sequence or structure. We discuss these results with regard to the mechanisms for spontaneous deletion in eucaryotic and procaryotic cells. PMID:3221864

Pulak, R A; Anderson, P

1988-09-01

130

Muscle arm development in Caenorhabditis elegans.  

PubMed

In several types of animals, muscle cells use membrane extensions to contact motor axons during development. To better understand the process of membrane extension in muscle cells, we investigated the development of Caenorhabditis elegans muscle arms, which extend to motor axons and form the postsynaptic element of the neuromuscular junction. We found that muscle arm development is a highly regulated process: the number of muscle arms extended by each muscle, the shape of the muscle arms and the path taken by the muscle arms to reach the motor axons are largely stereotypical. We also investigated the role of several cytoskeletal components and regulators during arm development, and found that tropomyosin (LEV-11), the actin depolymerizing activity of ADF/cofilin (UNC-60B) and, surprisingly, myosin heavy chain B (UNC-54) are each required for muscle arm extension. This is the first evidence that UNC-54, which is found in thick filaments of sarcomeres, can also play a role in membrane extension. The muscle arm phenotypes produced when these genes are mutated support a 'two-phase' model that distinguishes passive muscle arm development in embryogenesis from active muscle arm extension during larval development. PMID:15930100

Dixon, Scott J; Roy, Peter J

2005-07-01

131

The Caenorhabditis elegans septin complex is nonpolar  

PubMed Central

Septins are conserved GTPases that form heteromultimeric complexes and assemble into filaments that play a critical role in cell division and polarity. Results from budding and fission yeast indicate that septin complexes form around a tetrameric core. However, the molecular structure of the core and its influence on the polarity of septin complexes and filaments is poorly defined. The septin complex of the nematode Caenorhabditis elegans is formed entirely by the core septins UNC-59 and UNC-61. We show that UNC-59 and UNC-61 form a dimer of coiled-coil-mediated heterodimers. By electron microscopy, this heterotetramer appears as a linear arrangement of four densities representing the four septin subunits. Fusion of GFP to the N termini of UNC-59 and UNC-61 and subsequent electron microscopic visualization suggests that the sequence of septin subunits is UNC-59/UNC-61/UNC-61/UNC-59. Visualization of GFP extensions fused to the extremity of the C-terminal coiled coils indicates that these extend laterally from the heterotetrameric core. Together, our study establishes that the septin core complex is symmetric, and suggests that septins form nonpolar filaments. PMID:17599066

John, Corinne M; Hite, Richard K; Weirich, Christine S; Fitzgerald, Daniel J; Jawhari, Hatim; Faty, Mahamadou; Schläpfer, Dominik; Kroschewski, Ruth; Winkler, Fritz K; Walz, Tom; Barral, Yves; Steinmetz, Michel O

2007-01-01

132

Developmental genetics of the Caenorhabditis elegans pharynx  

PubMed Central

The Caenorhabditis elegans pharynx is a rhythmically pumping organ composed initially of 80 cells that, through fusions, amount to 62 cells in the adult worm. During the first 100 min of development, most future pharyngeal cells are born and gather into a double-plate primordium surrounded by a basal lamina. All pharyngeal cells express the transcription factor PHA-4, of which the concentration increases throughout development, triggering a sequential activation of genes with promoters responding differentially to PHA-4 protein levels. The oblong-shaped pharyngeal primordium becomes polarized, many cells taking on wedge shapes with their narrow ends toward the center, hence forming an epithelial cyst. The primordium then elongates, and reorientations of the cells at the anterior and posterior ends form the mouth and pharyngeal-intestinal openings, respectively. The 20 pharyngeal neurons establish complex but reproducible trajectories using ‘fishing line’ and growth cone-driven mechanisms, and the gland cells also similarly develop their processes. The genetics behind many fate decisions and morphogenetic processes are being elucidated, and reveal the pharynx to be a fruitful model for developmental biologists. PMID:25262818

Pilon, Marc

2014-01-01

133

CanProVar: A Human Cancer Proteome Variation Database  

PubMed Central

Identification and annotation of mutated genes or proteins involved in oncogenesis and tumor progression are crucial for both cancer biology and clinical applications. We have developed a human Cancer Proteome Variation Database (CanProVar) by integrating information on protein sequence variations from various public resources, with a focus on cancer-related variations. We have also built a user-friendly interface for querying the database. The current version of CanProVar comprises 8,570 cancer-related variations in 2,921 proteins derived from existing genome variation databases and recently published large-scale cancer genome re-sequencing studies. It also includes 41,541 non-cancer specific variations in 30,322 proteins derived from the dbSNP database. CanProVar provides quick access to known cancer-related variations in protein sequences along with related cancer samples, relevant publications, data sources, and functional information such as Gene Ontology annotations for the proteins, protein domains in which the variation occurs, and protein interaction partners with cancer-related variations. CanProVar also helps reveal functional characteristics of cancer-related variations and proteins bearing these variations. Our analysis showed that cancer-related variations were enriched in certain protein domains. We also showed that proteins bearing cancer-related variations were more likely to interact with each other in the protein interaction network. CanProVar can be accessed from http://bioinfo.vanderbilt.edu/canprovar. PMID:20052754

Li, Jing; Duncan, Dexter T.; Zhang, Bing

2009-01-01

134

The art and design of genetic screens: caenorhabditis elegans.  

PubMed

The nematode Caenorhabditis elegans was chosen as a model genetic organism because its attributes, chiefly its hermaphroditic lifestyle and rapid generation time, make it suitable for the isolation and characterization of genetic mutants. The most important challenge for the geneticist is to design a genetic screen that will identify mutations that specifically disrupt the biological process of interest. Since 1974, when Sydney Brenner published his pioneering genetic screen, researchers have developed increasingly powerful methods for identifying genes and genetic pathways in C. elegans. PMID:11988761

Jorgensen, Erik M; Mango, Susan E

2002-05-01

135

Imaging lipid metabolism in live Caenorhabditis elegans using fingerprint vibrations.  

PubMed

Quantitation of lipid storage, unsaturation, and oxidation in live C.?elegans has been a long-standing obstacle. The combination of hyperspectral stimulated Raman scattering imaging and multivariate analysis in the fingerprint vibration region represents a platform that allows the quantitative mapping of fat distribution, degree of fat unsaturation, lipid oxidation, and cholesterol storage in?vivo in the whole worm. Our results reveal for the first time that lysosome-related organelles in intestinal cells are sites for storage of cholesterol in C.?elegans. PMID:25195517

Wang, Ping; Liu, Bin; Zhang, Delong; Belew, Micah Y; Tissenbaum, Heidi A; Cheng, Ji-Xin

2014-10-27

136

Genomic analysis of gene expression in C. elegans.  

PubMed

Until now, genome-wide transcriptional profiling has been limited to single-cell organisms. The nematode Caenorhabditis elegans is a well-characterized metazoan in which the expression of all genes can be monitored by oligonucleotide arrays. We used such arrays to quantitate the expression of C. elegans genes throughout the development of this organism. The results provide an estimate of the number of expressed genes in the nematode, reveal relations between gene function and gene expression that can guide analysis of uncharacterized worm genes, and demonstrate a shift in expression from evolutionarily conserved genes to worm-specific genes over the course of development. PMID:11052945

Hill, A A; Hunter, C P; Tsung, B T; Tucker-Kellogg, G; Brown, E L

2000-10-27

137

Interkingdom signaling between pathogenic bacteria and Caenorhabditis elegans  

PubMed Central

Investigators have recently turned to the soil nematode Caenorhabditis elegans as a small animal infection model to study infectious disease. To extrapolate findings concerning bacterial pathogenesis from non-mammals to mammals, virulence factors should be conserved in function, independent of the infection model. Emerging from these studies is the observation that bacterial virulence regulatory networks function in a conserved manner across multiple hosts, including nematodes, mice, and plants. Several regulatory networks have been implicated in nematode innate immune function, and are being exploited in the C. elegans infection model to develop novel chemical therapies against bacterial pathogens. PMID:20667738

Mellies, Jay L.; Lawrence-Pine, Emily R.

2010-01-01

138

A Method for Evaluating Volt-VAR Optimization Field Demonstrations  

SciTech Connect

In a regulated business environment a utility must be able to validate that deployed technologies provide quantifiable benefits to the end-use customers. For traditional technologies there are well established procedures for determining what benefits will be derived from the deployment. But for many emerging technologies procedures for determining benefits are less clear and completely absent in some cases. Volt-VAR Optimization is a technology that is being deployed across the nation, but there are still numerous discussions about potential benefits and how they are achieved. This paper will present a method for the evaluation, and quantification of benefits, for field deployments of Volt-VAR Optimization technologies. In addition to the basic methodology, the paper will present a summary of results, and observations, from two separate Volt-VAR Optimization field evaluations using the proposed method.

Schneider, Kevin P.; Weaver, T. F.

2014-08-31

139

Identification of the varR Gene as a Transcriptional Regulator of Virginiamycin S Resistance in Streptomyces virginiae  

PubMed Central

A gene designated varR (for virginiae antibiotic resistance regulator) was identified in Streptomyces virginiae 89 bp downstream of a varS gene encoding a virginiamycin S (VS)-specific transporter. The deduced varR product showed high homology to repressors of the TetR family with a conserved helix-turn-helix DNA binding motif. Purified recombinant VarR protein was present as a dimer in vitro and showed clear DNA binding activity toward the varS promoter region. This binding was abolished by the presence of VS, suggesting that VarR regulates transcription of varS in a VS-dependent manner. Northern blot analysis revealed that varR was cotranscribed with upstream varS as a 2.4-kb transcript and that VS acted as an inducer of bicistronic transcription. Deletion analysis of the varS promoter region clarified two adjacent VarR binding sites in the varS promoter. PMID:11222601

Namwat, Wises; Lee, Chang-Kwon; Kinoshita, Hiroshi; Yamada, Yasuhiro; Nihira, Takuya

2001-01-01

140

BZ UMa and Var Her 04: Orphan TOADS  

NASA Astrophysics Data System (ADS)

Both BZ UMa and Var Her 04 are cataclysmic variable stars without a home. Neither fit easily into current classification systems so may extend the population distribution of two unique CV types: UGWZ dwarf novae and intermediate polars. New outburst photometry and archival X-Ray data shed some new light on BZ UMa's high energy state and new spectral and IR observations from Spitzer of dust around the newly discovered cataclysmic variable Var Her 04 may help find it a home as well.

Price, A.; Howell, S.

2005-05-01

141

Thermal Inactivation of Aerosolized Bacillus subtilis var. niger Spores  

PubMed Central

A hot-air sterilizer capable of exposing airborne microorganisms to elevated temperatures with an almost instantaneous heating time was developed and evaluated. With this apparatus, aerosolized Bacillus subtilis var. niger spores were killed in about 0.02 sec when exposed to temperatures above 260 C. This is about 500 times faster than killing times reported by others. Extrapolation and comparison of data on the time and temperature required to klll B. subtilis var. niger spores on surfaces show that approximately the same killing time is required as is necessary for spores in air, if corrections are made for the heating time of the surface. PMID:5002138

Mullican, Charles L.; Buchanan, Lee M.; Hoffman, Robert K.

1971-01-01

142

Histidine protects against zinc and nickel toxicity in Caenorhabditis elegans.  

PubMed

Zinc is an essential trace element involved in a wide range of biological processes and human diseases. Zinc excess is deleterious, and animals require mechanisms to protect against zinc toxicity. To identify genes that modulate zinc tolerance, we performed a forward genetic screen for Caenorhabditis elegans mutants that were resistant to zinc toxicity. Here we demonstrate that mutations of the C. elegans histidine ammonia lyase (haly-1) gene promote zinc tolerance. C. elegans haly-1 encodes a protein that is homologous to vertebrate HAL, an enzyme that converts histidine to urocanic acid. haly-1 mutant animals displayed elevated levels of histidine, indicating that C. elegans HALY-1 protein is an enzyme involved in histidine catabolism. These results suggest the model that elevated histidine chelates zinc and thereby reduces zinc toxicity. Supporting this hypothesis, we demonstrated that dietary histidine promotes zinc tolerance. Nickel is another metal that binds histidine with high affinity. We demonstrated that haly-1 mutant animals are resistant to nickel toxicity and dietary histidine promotes nickel tolerance in wild-type animals. These studies identify a novel role for haly-1 and histidine in zinc metabolism and may be relevant for other animals. PMID:21455490

Murphy, John T; Bruinsma, Janelle J; Schneider, Daniel L; Collier, Sara; Guthrie, James; Chinwalla, Asif; Robertson, J David; Mardis, Elaine R; Kornfeld, Kerry

2011-03-01

143

Blueberry polyphenols increase lifespan and thermotolerance in Caenorhabditis elegans  

PubMed Central

Summary The beneficial effects of polyphenol compounds in fruits and vegetables are mainly extrapolated from in vitro studies or short-term dietary supplementation studies. Due to cost and duration, relatively little is known about whether dietary polyphenols are beneficial in whole animals, particularly with respect to aging. To address this question, we examined the effects of blueberry polyphenols on lifespan and aging of the nematode, Caenorhabditis elegans, a useful organism for such a study. We report that a complex mixture of blue-berry polyphenols increased lifespan and slowed aging-related declines in C. elegans. We also found that these benefits did not just reflect antioxidant activity in these compounds. For instance, blueberry treatment increased survival during acute heat stress, but was not protective against acute oxidative stress. The blueberry extract consists of three major fractions that all contain antioxidant activity. However, only one fraction, enriched in proanthocyanidin compounds, increased C. elegans lifespan and thermotolerance. To further determine how polyphenols prolonged C. elegans lifespan, we analyzed the genetic requirements for these effects. Prolonged lifespan from this treatment required the presence of a CaMKII pathway that mediates osmotic stress resistance, though not other pathways that affect stress resistance and longevity. In conclusion, polyphenolic compounds in blueberries had robust and reproducible benefits during aging that were separable from antioxidant effects. PMID:16441844

Wilson, Mark A; Shukitt-Hale, Barbara; Kalt, Wilhelmina; Ingram, Donald K; Joseph, James A; Wolkow, Catherine A

2006-01-01

144

Identification of an estrogenic hormone receptor in Caenorhabditis elegans  

SciTech Connect

Changes in both behavior and gene expression occur in Caenorhabditis elegans following exposure to sex hormones such as estrogen and progesterone, and to bisphenol A (BPA), an estrogenic endocrine-disrupting compound. However, only one steroid hormone receptor has been identified. Of the 284 known nuclear hormone receptors (NHRs) in C. elegans, we selected nhr-14, nhr-69, and nhr-121 for analysis as potential estrogenic hormone receptors, because they share sequence similarity with the human estrogen receptor. First, the genes were cloned and expressed in Escherichia coli, and then the affinity of each protein for estrogen was determined using a surface plasmon resonance (SPR) biosensor. All three NHRs bound estrogen in a dose-dependent fashion. To evaluate the specificity of the binding, we performed a solution competition assay using an SPR biosensor. According to our results, only NHR-14 was able to interact with estrogen. Therefore, we next examined whether nhr-14 regulates estrogen signaling in vivo. To investigate whether these interactions actually control the response of C. elegans to hormones, we investigated the expression of vitellogenin, an estrogen responsive gene, in an nhr-14 mutant. Semi-quantitative RT-PCR showed that vitellogenin expression was significantly reduced in the mutant. This suggests that NHR-14 is a C. elegans estrogenic hormone receptor and that it controls gene expression in response to estrogen.

Mimoto, Ai; Fujii, Madoka [Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, 3-8-1 Komaba, Tokyo 153-8902 (Japan); Usami, Makoto [Division of Pharmacology, National Institute of Health Sciences, Tokyo (Japan); Shimamura, Maki; Hirabayashi, Naoko [Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, 3-8-1 Komaba, Tokyo 153-8902 (Japan); Department of Chemical and Biological Sciences, Faculty of Science, Japan Women's University, Tokyo (Japan); Kaneko, Takako [Department of Chemical and Biological Sciences, Faculty of Science, Japan Women's University, Tokyo (Japan); Sasagawa, Noboru [Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, 3-8-1 Komaba, Tokyo 153-8902 (Japan); Ishiura, Shoichi [Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, 3-8-1 Komaba, Tokyo 153-8902 (Japan)], E-mail: cishiura@mail.ecc.u-tokyo.ac.jp

2007-12-28

145

Genome-wide RNAi analysis of Caenorhabditis elegans  

E-print Network

regulation, and identify targets for treating obesity and its associated diseases. We used the vital dye Nile to Escherichia coli, the laboratory diet of C. elegans, resulted in uptake and incorporation of the dye that had been covalently labelled with the fluorescent dye BODIPY, and was similar to the pattern of fat

Ahringe, Julie

146

Dietary Supplementation of Polyunsaturated Fatty Acids in Caenorhabditis elegans  

PubMed Central

Fatty acids are essential for numerous cellular functions. They serve as efficient energy storage molecules, make up the hydrophobic core of membranes, and participate in various signaling pathways. Caenorhabditis elegans synthesizes all of the enzymes necessary to produce a range of omega-6 and omega-3 fatty acids. This, combined with the simple anatomy and range of available genetic tools, make it an attractive model to study fatty acid function. In order to investigate the genetic pathways that mediate the physiological effects of dietary fatty acids, we have developed a method to supplement the C. elegans diet with unsaturated fatty acids. Supplementation is an effective means to alter the fatty acid composition of worms and can also be used to rescue defects in fatty acid-deficient mutants. Our method uses nematode growth medium agar (NGM) supplemented with fatty acidsodium salts. The fatty acids in the supplemented plates become incorporated into the membranes of the bacterial food source, which is then taken up by the C. elegans that feed on the supplemented bacteria. We also describe a gas chromatography protocol to monitor the changes in fatty acid composition that occur in supplemented worms. This is an efficient way to supplement the diets of both large and small populations of C. elegans, allowing for a range of applications for this method. PMID:24326396

Deline, Marshall L.; Vrablik, Tracy L.; Watts, Jennifer L.

2013-01-01

147

WormBook: the online review of Caenorhabditis elegans biology.  

PubMed

WormBook (www.wormbook.org) is an open-access, online collection of original, peer-reviewed chapters on the biology of Caenorhabditis elegans and related nematodes. Since WormBook was launched in June 2005 with 12 chapters, it has grown to over 100 chapters, covering nearly every aspect of C.elegans research, from Cell Biology and Neurobiology to Evolution and Ecology. WormBook also serves as the text companion to WormBase, the C.elegans model organism database. Objects such as genes, proteins and cells are linked to the relevant pages in WormBase, providing easily accessible background information. Additionally, WormBook chapters contain links to other relevant topics in WormBook, and the in-text citations are linked to their abstracts in PubMed and full-text references, if available. Since WormBook is online, its chapters are able to contain movies and complex images that would not be possible in a print version. WormBook is designed to keep up with the rapid pace of discovery in the field of C.elegans research and continues to grow. WormBook represents a generic publishing infrastructure that is easily adaptable to other research communities to facilitate the dissemination of knowledge in the field. PMID:17099225

Girard, Lisa R; Fiedler, Tristan J; Harris, Todd W; Carvalho, Felicia; Antoshechkin, Igor; Han, Michael; Sternberg, Paul W; Stein, Lincoln D; Chalfie, Martin

2007-01-01

148

Transcriptional analysis of Pseudomonas aeruginosa infected Caenorhabditis elegans.  

PubMed

Here, we describe a protocol for the extraction of total RNA from C. elegans infected with P. aeruginosa. The protocol excludes P. aeruginosa cells that have not been ingested by the nematodes and yields total RNA that can be used for detection of transcripts from both host and pathogen. PMID:24818936

MacKenzie, Ashleigh; Stewart, Lewis; Hoskisson, Paul A; Tucker, Nicholas P

2014-01-01

149

Toxicological Effects of Cerium Oxide Nanoparticle Aggregates on Caenorhabditis elegans  

NASA Astrophysics Data System (ADS)

Assessing the toxicity and unique reactivity of nanoparticles in biological systems has become an relevant and quickly growing area of environmental toxicology research. The broad use of nanoparticles in industrial and commercial commodities results in exposure of these nano-compounds to the environment, the ecosystems, and humans. While previous data has suggested that cerium oxide (CeO 2) nanoparticles are relatively safe to cultured cells much less is known about the potential toxicity of these materials at the organismal level. In this study we employed transgenic Caenorhabditis elegans (C. elegans) strains to assess the toxicity of CeO2 nanoparticles under "real-world" conditions. Our findings indicate that while exposure to aggregated CeO2 in C. elegans has no effect on average life span, it is associated with decreases in nematode body length, progeny count, and increased organismal stress. These findings demonstrate that exposure to aggregated CeO2 particles (0-17.21 ug/mL) may be associated with diminished organismal fitness in C. elegans..

Rebola, Alejandro Federico

150

Real-time Embryogenesis in Live Caenorhabditis elegans Worms  

NSDL National Science Digital Library

This is a lab exercise geared toward first-year undergraduate biology majors, where they get to view early embryogenesis in a live animal. In this exercise students will prepare slides if live C. elegans embryos, find one- or two-cell stage embryos, and observe cleavage stage of embryogenesis over the course of 30 minutes.

Dr. Anita G Fernandez (Fairfield University Biology); Ian Chin-Sing (Queens University)

2011-11-21

151

INTRODUCTION The worm Caenorhabditis elegans generally employs three types  

E-print Network

1554 INTRODUCTION The worm Caenorhabditis elegans generally employs three types of crawling modes reorientations. However, in the presence of attractants, worms are able to track gradients using a biased random in the absence of food, worms also exhibit a large number of small angle turns by forming higher or lower

Mahadevan, L.

152

Optogenetic manipulation of neural activity in freely moving Caenorhabditis elegans  

Microsoft Academic Search

We present an optogenetic illumination system capable of real-time light delivery with high spatial resolution to specified targets in freely moving Caenorhabditis elegans. A tracking microscope records the motion of an unrestrained worm expressing channelrhodopsin-2 or halorhodopsin in specific cell types. Image processing software analyzes the worm's position in each video frame, rapidly estimates the locations of targeted cells and

Andrew M Leifer; Marc Gershow; Mark J Alkema; Christopher Fang-Yen; Aravinthan D T Samuel

2011-01-01

153

Caenorhabditis elegans glia modulate neuronal activity and behavior  

PubMed Central

Glial cells of Caenorhabditis elegans can modulate neuronal activity and behavior, which is the focus of this review. Initially, we provide an overview of neuroglial evolution, making a comparison between C. elegans glia and their genealogical counterparts. What follows is a brief discussion on C. elegans glia characteristics in terms of their exact numbers, germ layers origin, their necessity for proper development of sensory organs, and lack of their need for neuronal survival. The more specific roles that various glial cells have on neuron-based activity/behavior are succinctly presented. The cephalic sheath glia are important for development, maintenance and activity of central synapses, whereas the amphid glia seem to set the tone of sensory synapses; these glial cell types are ectoderm-derived. Mesoderm-derived Glial-Like cells in the nerve Ring (GLRs) appear to be a part of the circuit for production of motor movement of the worm anterior. Finally, we discuss tools and approaches utilized in studying C. elegans glia, which are assets available for this animal, making it an appealing model, not only in neurosciences, but in biology in general. PMID:24672428

Stout Jr., Randy F.; Verkhratsky, Alexei; Parpura, Vladimir

2014-01-01

154

Toxicity of Polycyclic Aromatic Hydrocarbons to the Nematode Caenorhabditis elegans  

Microsoft Academic Search

The presence of polycyclic aromatic hydrocarbons (PAHs) in the environment has attracted much concern owing to their mutagenic and carcinogenic properties. Regulatory authorities have favored the use of biological indicators as an essential means of assessing potential toxicity of environmental pollutants. This study aimed to assess the toxicity of acenaphthene, phenanthrene, anthracene, fluoranthene, pyrene, and benzo[a]pyrene to Caenorhabditis elegans by

Beke T. Sese; Alastair Grant; Brian J. Reid

2009-01-01

155

Analysis of Wnt Signaling During Caenorhabditis elegans Postembryonic Development  

E-print Network

cell niche. Perturbations in Wnt signaling are also key factors in cancer formation, and therefore an overview of methods used to observe their function. Key words: C. elegans, Wnt signaling, cell polarity cells and tissue types in all species studied to date. Like many other extracellular signaling pathways

Kaufman, Glennis A.

156

Genetics: Influence of TOR kinase on lifespan in C. elegans  

Microsoft Academic Search

The group of enzymes known as TOR (for 'target of rapamycin') kinases regulates cell growth and proliferation in response to nutrients and hormone-dependent mitogenic signals. Here we show that TOR deficiency in the nematode Caenorhabditis elegans more than doubles its natural lifespan. This new function for TOR signalling in ageing control may represent a link between nutrition, metabolism and longevity.

Tibor Vellai; Krisztina Takacs-Vellai; Yue Zhang; Attila L. Kovacs; László Orosz; Fritz Müller

2003-01-01

157

Multiple ERK substrates execute single biological processes in Caenorhabditis elegans  

E-print Network

Multiple ERK substrates execute single biological processes in Caenorhabditis elegans germ, 2008) RAS-extracellular signal regulated kinase (ERK) signaling governs multiple aspects of cell fate. Understanding how perturbations to the ERK signaling pathway lead to developmental disorders and cancer hinges

158

Molecular profiling of mitochondrial dysfunction in Caenorhabditis elegans  

PubMed Central

Cellular effects of primary mitochondrial dysfunction, as well as potential mitochondrial disease therapies, can be modeled in living animals such as the microscopic nematode, Caenorhabditis elegans. In particular, molecular analyses can provide substantial insight into the mechanism by which genetic and/or pharmacologic manipulations alter mitochondrial function. The relative expression of individual genes across both nuclear and mitochondrial genomes, as well as relative quantitation of mitochondrial DNA content, can be readily performed by quantitative Real-Time PCR (qRT-PCR) analysis of C. elegans. Additionally, microarray expression profiling offers a powerful tool by which to survey the global genetic consequences of various causes of primary mitochondrial dysfunction and potential therapeutic interventions at both the single gene and integrated pathway level. Here, we describe detailed protocols for RNA and DNA isolation from whole animal populations in C. elegans, qRT-PCR analysis of both nuclear and mitochondrial genes, and global nuclear genome expression profiling using the Affymetrix GeneChip C. elegans Genome Array. PMID:22215553

Polyak, Erzsebet; Zhang, Zhe; Falk, Marni J.

2013-01-01

159

Caenorhabditis elegans development requires mitochondrial function in the nervous system  

Microsoft Academic Search

The mitochondrial respiratory chain (MRC) supplies the majority of the energy requirements of most eucaryotic cells. A null mutation in the Caenorhabditis elegans nuo-1 gene encoding a subunit of complex I (NADH–ubiquinone oxidoreductase) is lethal, leading to a developmental arrest at the third larval stage. To identify the tissues that regulate development in response to mitochondrial dysfunction, we restored nuo-1

Sarah Ndegwa; Bernard D. Lemire

2004-01-01

160

Electrical activity and behavior in the pharynx of caenorhabditis elegans  

Microsoft Academic Search

Summary The pharynx of C. elegans, a model system for neural networks and for membrane excitability, has been chiefly studied by observing its behavior in normal worms, in mutant worms, and in worms lacking pharyn- geal neurons. To complement this behavioral approach, we devised a method for recording currents produced by changes in pharyngeal muscle membrane potential. The electrical records,

David M. Raizen; Leon Avery

1994-01-01

161

IgCAMs redundantly control axon navigation in Caenorhabditis elegans  

Microsoft Academic Search

BACKGROUND: Cell adhesion molecules of the immunoglobulin superfamily (IgCAMs) form one of the largest and most diverse families of adhesion molecules and receptors in the nervous system. Many members of this family mediate contact and communication among neurons during development. The Caenorhabditis elegans genome contains a comparatively small number of IgCAMs, most of which are evolutionarily conserved and found across

Valentin Schwarz; Jie Pan; Susanne Voltmer-Irsch; Harald Hutter

2009-01-01

162

TILLING is an effective reverse genetics technique for Caenorhabditis elegans  

Microsoft Academic Search

BACKGROUND: TILLING (Targeting Induced Local Lesions in Genomes) is a reverse genetic technique based on the use of a mismatch-specific enzyme that identifies mutations in a target gene through heteroduplex analysis. We tested this technique in Caenorhabditis elegans, a model organism in which genomics tools have been well developed, but limitations in reverse genetics have restricted the number of heritable

Erin J Gilchrist; Nigel J O'Neil; Ann M Rose; Monique C Zetka; George W Haughn

2006-01-01

163

Homologous gene targeting in Caenorhabditis elegans by biolistic transformation  

Microsoft Academic Search

Targeted homologous recombination is a powerful approach for genome manipulation that is widely used for gene alteration and knockouts in mouse and yeast. In Caenorhabditis elegans, several meth- ods of target-selected mutagenesis have been implemented but none of them provides the oppor- tunity of introducing exact predefined changes into the genome. Although anecdotal cases of homolo- gous gene targeting in

Eugene Berezikov; Cornelia I. Bargmann; Ronald H. A. Plasterk

2004-01-01

164

Targeted gene alteration in Caenorhabditis elegans by gene conversion  

Microsoft Academic Search

Now that some genomes have been completely sequenced, the ability to direct specific mutations into genomes is particularly desirable. Here we present a method to create mutations in the Caenorhabditis elegans genome efficiently through transgene-directed, transposon-mediated gene conversion. Engineered deletions targeted into two genes show that the frequency of obtaining the desired mutation was higher using this approach than using

Peter L Barrett; John T Fleming; Verena Göbel

2004-01-01

165

Functional Requirement for Histone Deacetylase 1 in Caenorhabditis elegans Gonadogenesis  

Microsoft Academic Search

Histone acetylation and deacetylation have been implicated in the regulation of gene expression. Molecular studies have shown that histone deacetylases (HDACs) function as transcriptional repressors. However, very little is known about their roles during development in multicellular organisms. We previously demonstrated that inhibition of maternal and zygotic expression of histone deacetylase 1 (HDA-1) causes embryonic lethality in Caenorhabditis elegans. Here,

Pascale Dufourcq; Martin Victor; Frédérique Gay; Jonathan Hodgkin; Yang Shi

2002-01-01

166

Single-copy insertion of transgenes in Caenorhabditis elegans  

Microsoft Academic Search

At present, transgenes in Caenorhabditis elegans are generated by injecting DNA into the germline. The DNA assembles into a semistable extrachromosomal array composed of many copies of injected DNA. These transgenes are typically overexpressed in somatic cells and silenced in the germline. We have developed a method that inserts a single copy of a transgene into a defined site. Mobilization

Christian Frøkjær-Jensen; M Wayne Davis; Christopher E Hopkins; Blake J Newman; Jason M Thummel; Søren-Peter Olesen; Morten Grunnet; Erik M Jorgensen

2008-01-01

167

ROS in Aging Caenorhabditis elegans: Damage or Signaling?  

PubMed Central

Many insights into the mechanisms and signaling pathways underlying aging have resulted from research on the nematode Caenorhabditis elegans. In this paper, we discuss the recent findings that emerged using this model organism concerning the role of reactive oxygen species (ROS) in the aging process. The accrual of oxidative stress and damage has been the predominant mechanistic explanation for the process of aging for many years, but reviewing the recent studies in C. elegans calls this theory into question. Thus, it becomes more and more evident that ROS are not merely toxic byproducts of the oxidative metabolism. Rather it seems more likely that tightly controlled concentrations of ROS and fluctuations in redox potential are important mediators of signaling processes. We therefore discuss some theories that explain how redox signaling may be involved in aging and provide some examples of ROS functions and signaling in C. elegans metabolism. To understand the role of ROS and the redox status in physiology, stress response, development, and aging, there is a rising need for accurate and reversible in vivo detection. Therefore, we comment on some methods of ROS and redox detection with emphasis on the implementation of genetically encoded biosensors in C. elegans. PMID:22966416

Back, Patricia; Braeckman, Bart P.; Matthijssens, Filip

2012-01-01

168

A pharmacological network for lifespan extension in Caenorhabditis elegans  

PubMed Central

One goal of aging research is to find drugs that delay the onset of age-associated disease. Studies in invertebrates, particularly Caenorhabditis elegans, have uncovered numerous genes involved in aging, many conserved in mammals. However, which of these encode proteins suitable for drug targeting is unknown. To investigate this question, we screened a library of compounds with known mammalian pharmacology for compounds that increase C. elegans lifespan. We identified 60 compounds that increase longevity in C. elegans, 33 of which also increased resistance to oxidative stress. Many of these compounds are drugs approved for human use. Enhanced resistance to oxidative stress was associated primarily with compounds that target receptors for biogenic amines, such as dopamine or serotonin. A pharmacological network constructed with these data reveal that lifespan extension and increased stress resistance cluster together in a few pharmacological classes, most involved in intercellular signaling. These studies identify compounds that can now be explored for beneficial effects on aging in mammals, as well as tools that can be used to further investigate the mechanisms underlying aging in C. elegans. PMID:24134630

Ye, Xiaolan; Linton, James M; Schork, Nicholas J; Buck, Linda B; Petrascheck, Michael

2014-01-01

169

The C. elegans Rab Family: Identification, Classification and Toolkit Construction  

PubMed Central

Rab monomeric GTPases regulate specific aspects of vesicle transport in eukaryotes including coat recruitment, uncoating, fission, motility, target selection and fusion. Moreover, individual Rab proteins function at specific sites within the cell, for example the ER, golgi and early endosome. Importantly, the localization and function of individual Rab subfamily members are often conserved underscoring the significant contributions that model organisms such as Caenorhabditis elegans can make towards a better understanding of human disease caused by Rab and vesicle trafficking malfunction. With this in mind, a bioinformatics approach was first taken to identify and classify the complete C. elegans Rab family placing individual Rabs into specific subfamilies based on molecular phylogenetics. For genes that were difficult to classify by sequence similarity alone, we did a comparative analysis of intron position among specific subfamilies from yeast to humans. This two-pronged approach allowed the classification of 30 out of 31 C. elegans Rab proteins identified here including Rab31/Rab50, a likely member of the last eukaryotic common ancestor (LECA). Second, a molecular toolset was created to facilitate research on biological processes that involve Rab proteins. Specifically, we used Gateway-compatible C. elegans ORFeome clones as starting material to create 44 full-length, sequence-verified, dominant-negative (DN) and constitutive active (CA) rab open reading frames (ORFs). Development of this toolset provided independent research projects for students enrolled in a research-based molecular techniques course at California State University, East Bay (CSUEB). PMID:23185324

Gallegos, Maria E.; Balakrishnan, Sanjeev; Chandramouli, Priya

2012-01-01

170

Disruption of Iron Homeostasis Increases Phosphine Toxicity in Caenorhabditis elegans  

E-print Network

Disruption of Iron Homeostasis Increases Phosphine Toxicity in Caenorhabditis elegans Ubon Cha-dependent actions of phosphine, in vitro: (1) reduction of ferric iron (Fe3+ ) to ferrous iron (Fe2+ ), (2) release of iron from horse ferritin, (3) and the peroxidation of lipid as a result of iron release from ferritin

Hammock, Bruce D.

171

Noncanonical cell death programs in the nematode Caenorhabditis elegans  

E-print Network

Review Noncanonical cell death programs in the nematode Caenorhabditis elegans ES Blum1 , M (caspase), which function in a linear pathway to promote developmental cell death in this organism. While this core pathway functions in many cells, recent studies suggest that additional regulators, acting

Shaham, Shai

172

Genes that regulate both development and longevity in Caenorhabditis elegans  

Microsoft Academic Search

The nematode Caenorhabditis elegans responds to conditions of overcrowding and limited food by arresting development as a dauer larva. Genetic analysis of mutations that alter dauer larva formation (daf mutations) is presented along with an updated genetic pathway for dauer vs. nondauer development. Mutations in the daf-2 and daf-23 genes double adult life span, whereas mutations in four other dauer-constitutive

Pamela L. Larsen; Patrice S. Albert; Donald L. Riddle

1995-01-01

173

Active uptake of artificial particles in the nematode Caenorhabditis elegans.  

PubMed

Feeding and food choice are crucial to the survival of an animal. The nematode Caenorhabditis elegans feeds on various microorganisms in nature, and is usually fed Escherichia coli in the laboratory. To elucidate the mechanisms of food/non-food discrimination in C. elegans, we examined the accumulation of various fluorescent polystyrene microspheres in the absence and presence of bacterial food. In the absence of food and on agar plates, C. elegans worms actively accumulated 0.5 and 1 ?m diameter microspheres, whereas those microspheres <0.5 ?m or >3 ?m were rarely accumulated. Carboxylate microspheres were accumulated more than sulfate or amine microspheres. These results of accumulation in the absence of food probably well simulate uptake of or feeding on the microspheres. Presence of food bacteria even at bacteria:nematode ratios of 1:100 or 1:10 significantly reduced accumulation of 0.5 ?m microspheres, and accumulation was reduced to approximately one-fourth of that observed in the absence of bacteria at a ratio of 1:1. When accumulation of microspheres was examined with the chemical sense mutants che-2, tax-2, odr-1 and odr-2, or the feeding mutant eat-1, all the mutants showed less accumulation than the wild type in the absence of food. In the presence of food, the che-2 mutant showed more accumulation than the wild type. It is possible that C. elegans discriminates food both physically, based on size, and chemically, based on taste and olfaction. PMID:22399663

Kiyama, Yuya; Miyahara, Kohji; Ohshima, Yasumi

2012-04-01

174

Population Genomics of the Immune Evasion (var) Genes of Plasmodium falciparum  

Microsoft Academic Search

Var genes encode the major surface antigen (PfEMP1) of the blood stages of the human malaria parasite Plasmodium falciparum. Differential expression of up to 60 diverse var genes in each parasite genome underlies immune evasion. We compared the diversity of the DBL? domain of var genes sampled from 30 parasite isolates from a malaria endemic area of Papua New Guinea

Alyssa E Barry; Aleksandra Leliwa-Sytek; Livingston Tavul; Heather Imrie; Florence Migot-Nabias; Stuart M Brown; Gilean A. V McVean; Karen P Day

2007-01-01

175

Research of static var compensator control system based on DSP technology  

Microsoft Academic Search

We present the principle of the Static Var Compensator, and introduce the design of a static var compensator control system. The design techniques of DSP CPU board and signal conditioning circuit is analyzed in this paper. We describe the fast algorithm solving reactive power and PID algorithm with variable parameter avoiding integral saturation in detail. The performance of static var

Chang-yong Zheng

2010-01-01

176

The development of RAPD and microsatellite markers in lodgepole pine (Pinus contorta var.  

E-print Network

The development of RAPD and microsatellite markers in lodgepole pine (Pinus contorta var. latifolia pine (Pinus contorta var. latifolia) have been developed. We detected 52 decameric oligonucleotides polymorphism, RAPD, microsatellite, SSR, Pinus contorta var. latifolia. Résumé : Deux types de marqueurs

Macdonald, Ellen

177

Optimality of 4D-Var and its relationship with the Kalman lter and Kalman smoother  

E-print Network

Optimality of 4D-Var and its relationship with the Kalman #12;lter and Kalman smoother Zhijin Li-Var and the Kalman #12;lter as well as the #12;xed-interval Kalman smoother point to particular optimal properties irrespective of whether the model is perfect or not. Various properties of equivalence of 4D-Var to the Kalman

Aluffi, Paolo

178

ccsd00001214 VAR AND ES FOR LINEAR PORTFOLIOS WITH MIXTURE OF  

E-print Network

, as an alternative to Monte Carlo, use #1;-normal VaR methodology, in which the portfolio return is linearlyccsd­00001214 (version 1) : 27 Feb 2004 VAR AND ES FOR LINEAR PORTFOLIOS WITH MIXTURE OF ELLIPTIC-Kamdem [3], we give and explicit formula to estimate linear VaR and ES when the risk factors changes

179

Recombinational Landscape and Population Genomics of Caenorhabditis elegans  

PubMed Central

Recombination rate and linkage disequilibrium, the latter a function of population genomic processes, are the critical parameters for mapping by linkage and association, and their patterns in Caenorhabditis elegans are poorly understood. We performed high-density SNP genotyping on a large panel of recombinant inbred advanced intercross lines (RIAILs) of C. elegans to characterize the landscape of recombination and, on a panel of wild strains, to characterize population genomic patterns. We confirmed that C. elegans autosomes exhibit discrete domains of nearly constant recombination rate, and we show, for the first time, that the pattern holds for the X chromosome as well. The terminal domains of each chromosome, spanning about 7% of the genome, exhibit effectively no recombination. The RIAILs exhibit a 5.3-fold expansion of the genetic map. With median marker spacing of 61 kb, they are a powerful resource for mapping quantitative trait loci in C. elegans. Among 125 wild isolates, we identified only 41 distinct haplotypes. The patterns of genotypic similarity suggest that some presumed wild strains are laboratory contaminants. The Hawaiian strain, CB4856, exhibits genetic isolation from the remainder of the global population, whose members exhibit ample evidence of intercrossing and recombining. The population effective recombination rate, estimated from the pattern of linkage disequilibrium, is correlated with the estimated meiotic recombination rate, but its magnitude implies that the effective rate of outcrossing is extremely low, corroborating reports of selection against recombinant genotypes. Despite the low population, effective recombination rate and extensive linkage disequilibrium among chromosomes, which are techniques that account for background levels of genomic similarity, permit association mapping in wild C. elegans strains. PMID:19283065

Rockman, Matthew V.; Kruglyak, Leonid

2009-01-01

180

In vitro Micrografting of Mature Pistachio ( Pistacia vera var. Siirt)  

Microsoft Academic Search

The success of various in vitro micrografting methods of shoot tips of pistachio (Pistacia vera L. var. Siirt) have been examined. Excised zygotic embryos that germinated in vitro were used as rootstocks. Current year shoot tips from mature trees of pistachio micrografted onto in vitro juvenile rootstocks, resulted in the restoration of shoot-bud proliferation. Variables tested include a size of

A. Onay; V. Pirinç; H. Y?ld?r?m; D. Basaran

2004-01-01

181

A Preliminary Study of Acarospora smaragdula var. lesdainii in California  

Microsoft Academic Search

1 ABSTRACT. - The current state of Acarospora studies is discussed. Acarospora hassei Herre and Acarospora particularis H. Magnusson are placed in synonymy with Acarospora smaragdula var. lesdainii (Harmand in A.L. Smith) H. Magnusson. A lectotype is selected for A. hassei Herre.

KERRY KNUDSEN

182

Major anthocyanin from ripe berries of Cleistocalyx nervosum var. paniala  

Microsoft Academic Search

Cleistocalyx nervosum var. paniala (known as Ma kiang) is found growing in scatter locations in some villages of the northern provinces of Thailand. The rich purplish red color of Ma kiang is characterized by an anthocyanin profile. It is now popular for functional health food, cosmetic ingredients and health drinks. The aim of this study was to identify the anthocyanins

Chalerm Jansom; Sutatip Bhamarapravati; Arunporn Itharat

183

An epoxidized iridal from Iris germanica var “Rococo”  

Microsoft Academic Search

A new iridal has been isolated from rhizomes of Iris germanica var. “Rococo”. On the basis of spectral data, its structure was established as 18,19-epoxy-10-deoxyiridal (5). This compound is the first epoxidized iridal discovered so far.

Jean-Paul Bonfils; Franz-Josef Marner; Yves Sauvaire

1998-01-01

184

Aberrant meiotic behavior in Agave tequilana Weber var. azul  

Microsoft Academic Search

BACKGROUND: Agave tequilana Weber var. azul, is the only one variety permitted by federal law in México to be used for tequila production which is the most popular contemporary alcoholic beverage made from agave and recognized worldwide. Despite the economic, genetic, and ornamental value of the plant, it has not been subjected to detailed cytogenetic research, which could lead to

Domingo Ruvalcaba-Ruiz; Benjamin Rodríguez-Garay

2002-01-01

185

New diterpenes from the heartwood of Chamaecyparis obtusa var. formosana.  

PubMed

An abietane diterpene, 11,14-dihydroxy-8,11,13-abietatrien-7-one (1); a seco-abietane diterpene, obtuanhydride (2); and an isopimarane diterpene, 18,19-O-isopropylidene-18, 19-dihydroxyisopimara-8(14),15-diene (3) were isolated from the heartwood of Chamaecyparis obtusa var. formosana. The structures of these new compounds were elucidated by spectroscopic methods. PMID:9644078

Kuo, Y H; Chen, C H; Huang, S L

1998-06-26

186

Original article Residues in wax and honey after Apilife VAR®  

E-print Network

Original article Residues in wax and honey after Apilife VAR® treatment Stefan Bogdanov Anton and foundation were exposed to the air during storage. © Inra/DIB/AGIB/Elsevier, Paris honey / wax / residue to accumulation of these substances in beeswax and less so in honey [1, 17]. The accumulation in wax depends

Paris-Sud XI, Université de

187

Cytotoxic constituents from Solidago virga-aurea var. gigantea MIQ  

Microsoft Academic Search

Activity-guided fractionation of the whole plant ofSolidago virga-aurea var.gigantea MIQ. (Compositae) has led to the isolation of three cytotoxic compounds, erythrodiol-3-acetate (1), ?-tocopherol-quinone (2), and trans-phytol (3) from the hexane soluble fraction. It is the first report of those compounds from the genus.

Jong Hoon Sung; Jung Ock Lee; Jong Kun Son; No Sang Park; Mi Ran Kim; Jae Gil Kim; Dong Cheul Moon

1999-01-01

188

Cytotoxic constituents from Solidago virga-aurea var. gigantea MIQ.  

PubMed

Activity-guided fractionation of the whole plant of Solidago virga-aurea var. gigantea M(IQ). (Compositae) has led to the isolation of three cytotoxic compounds, erythrodiol-3-acetate (1), alpha-tocopherol-quinone (2), and trans-phytol (3) from the hexane soluble fraction. It is the first report of those compounds from the genus. PMID:10615872

Sung, J H; Lee, J O; Son, J K; Park, N S; Kim, M R; Kim, J G; Moon, D C

1999-12-01

189

PHYTOCHEMICAL INVESTIGATION ON THE LEAVES OF DODONAEA VISCOSA var. ANGUSTIFOLIA.  

E-print Network

??The petroleum ether extract of the leaves of Dodonaea viscosa var. angustifolia afforded a diterpene 5-(2-(furan-3-yl)ethyl)-3,4,4a,5,6,7,8,8a-octahydro-8 hydroxy-5,6,8a-trimethylnaphthalene-1-carboxylic acid (compound Dc-8B) whereas the chloroform extract gave… (more)

Dessalegn, Bekele

2009-01-01

190

Chemopreventive and Anticancer Activities of Allium victorialis var. platyphyllum Extracts  

PubMed Central

Background: Allium victorialis var. platyphyllum is an edible perennial herb and has been used as a vegetable or as a Korean traditional medicine. Allium species have received much attention owing to their diverse pharmacological properties, including antioxidative, anti-inflammatory, and anticancer activities. However, A. victorialis var. platyphyllum needs more study. Methods: The chemopreventive potential of A. victorialis var. platyphyllum methanol extracts was examined by measuring 12-O-tetra-decanoylphorbol 13-acetate (TPA)-induced superoxide anion production in the differentiated HL-60 cells, TPA-induced mouse ear edema, and Ames/Salmonella mutagenicity. The apoptosis-inducing capabilities of the extracts were evaluated by the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide assay, 4’,6-diamidino-2-phenylindole staining, and the DNA fragmentation assay in human colon cancer HT-29 cells. Antimetastatic activities of the extracts were also investigated in an experimental mouse lung metastasis model. Results: The methanol extracts of A. victorialis var. platyphyllum rhizome (AVP-R) and A. victorialis var. platyphyllum stem (AVP-S) dose-dependently inhibited the TPA-induced generation of superoxide anion in HL-60 cells and TPA-induced ear edema in mice, as well as 7,12-dimethylbenz[a]anthracene (DMBA) and tert-butyl hydroperoxide (t-BOOH) -induced bacterial mutagenesis. AVP-R and AVP-S reduced cell viability in a dose-related manner and induced apoptotic morphological changes and internucleosomal DNA fragmentation in HT-29 cells. In the experimental mouse lung metastasis model, the formation of tumor nodules in lung tissue was significantly inhibited by the treatment of the extracts. Conclusions: AVP-R and AVP-S possess antioxidative, anti-inflammatory, antimutagenic, proapoptotic, and antimetastatic activities. Therefore, these extracts can serve as a beneficial supplement for the prevention and treatment of cancer. PMID:25337587

Kim, Hyun-Jeong; Park, Min Jeong; Park, Hee-Juhn; Chung, Won-Yoon; Kim, Ki-Rim; Park, Kwang-Kyun

2014-01-01

191

The C. elegans heterochronic gene lin-4 encodes small RNAs with antisense complementarity to lin-14  

Microsoft Academic Search

Summary h-4 is essential for the normal temporal control of diverse postembryonic developmental events in C. elegans. \\/in-4 acts by negatively regulating the level of LIN-14 protein, creating a temporal decrease in LIN-14 protein starting in the first larval stage (Ll). We have cloned the C. elegans lin-4 locus by chromosomal walking and transformation rescue. We used the C. elegans

Rosalind C. Lee; Rhonda L. Feinbaum; Victor Ambros

1993-01-01

192

The pathogen Pseudomonas aeruginosa negatively affects the attraction response of the nematode Caenorhabditis elegans to bacteria.  

PubMed

The nematode Caenorhabditis elegans has previously been used to identify virulence mechanisms of bacteria and to characterise host responses to infection. In this study, we have developed an assay to measure C. elegans attraction to bacterial food sources. C. elegans becomes less attracted to the bacterial pathogen Pseudomonas aeruginosa strain PA14 over time, but this response is not seen with P. aeruginosa strains PAK1 or PA01. P. aeruginosa strain PA14 cells that had been killed by UV light, or which had been exposed to chloramphenicol, did not mediate this effect. We therefore propose that C. elegans reacts to a factor produced by P. aeruginosa strain PA14. PMID:16678995

Laws, Thomas R; Atkins, Helen S; Atkins, Timothy P; Titball, Richard W

2006-06-01

193

Wnt and EGF pathways act together to induce C. elegans male hook development  

E-print Network

Comparative studies of vulva development between Caenorhabditis elegans and other nematode species have provided some insight into the evolution of patterning networks. However, molecular genetic details are available ...

Sternberg, Paul W.

194

Propulsion by sinusoidal locomotion: A motion inspired by Caenorhabditis elegans  

NASA Astrophysics Data System (ADS)

Sinusoidal locomotion is commonly seen in snakes, fish, nematodes, or even the wings of some birds and insects. This doctoral thesis presents the study of sinusoidal locomotion of the nematode C. elegans in experiments and the application of the state-space airloads theory to the theoretical forces of sinusoidal motion. An original MATLAB program has been developed to analyze the video records of C. elegans' movement in different fluids, including Newtonian and non-Newtonian fluids. The experimental and numerical studies of swimming C. elegans has revealed three conclusions. First, though the amplitude and wavelength are varying with time, the motion of swimming C. elegans can still be viewed as sinusoidal locomotion with slips. The average normalized wavelength is a conserved character of the locomotion for both Newtonian and non-Newtonian fluids. Second, fluid viscosity affects the frequency but not the moving speed of C. elegans, while fluid elasticity affects the moving speed but not the frequency. Third, by the resistive force theory, for more elastic fluids the ratio of resistive coefficients becomes smaller. Inspired by the motion of C. elegans and other animals performing sinusoidal motion, we investigated the sinusoidal motion of a thin flexible wing in theory. Given the equation of the motion, we have derived the closed forms of propulsive force, lift and other generalized forces applying on the wing. We also calculated the power required to perform the motion, the power lost due to the shed vortices and the propulsive efficiency. These forces and powers are given as functions of reduced frequency k, dimensionless wavelength z, dimensionless amplitude A/b, and time. Our results show that a positive, time-averaged propulsive force is produced for all k>k0=pi/ z. At k=k0, which implies the moment when the moving speed of the wing is the same as the wave speed of its undulation, the motion reaches a steady state with all forces being zero. If there were no shed vorticity effects, the propulsive force would be zero at z = 0.569 and z = 1.3 for all k, and for a fixed k the wing would gain the optimal propulsive force when z = 0.82. With the effects of shed vorticity, the propulsive efficiency decreases from 1.0 to 0.5 as k goes to infinity, and the propulsive efficiency increases almost in a linear relationship with k0.

Ulrich, Xialing

195

Functional Analyses of Vertebrate TCF Proteins in C. elegans Embryos  

PubMed Central

In the canonical Wnt pathway, signaling results in the stabilization and increased levels of ?-catenin in responding cells. ?-catenin then enters the nucleus, functioning as a coactivator for the Wnt effector, TCF/LEF protein. In the absence of Wnt signaling, TCF is complexed with corepressors, together repressing Wnt target genes. In C. elegans, Wnt signaling specifies the E blastomere to become the endoderm precursor. Activation of endoderm genes in E requires not only an increase in ?-catenin level, but a concomitant decrease in the nuclear level of POP-1, the sole C. elegans TCF. A decrease in nuclear POP-1 levels requires Wnt-induced phosphorylation of POP-1 and 14-3-3 protein-mediated nuclear export. Nuclear POP-1 levels remain high in the sister cell of E, MS, where POP-1 represses the expression of endoderm genes. Here we express three vertebrate TCF proteins (human TCF4, mouse LEF1 and Xenopus TCF3) in C. elegans embryos and compare their localization, repression and activation functions to POP-1. All three TCFs are localized to the nucleus in C. elegans embryos, but none undergoes Wnt-induced nuclear export. Although unable to undergo Wnt-induced nuclear export, human TCF4, but not mouse LEF1 or Xenopus TCF3, can repress endoderm genes in MS, in a manner very similar to POP-1. This repressive activity requires that human TCF4 recognize specific promoter sequences upstream of endoderm genes and interact with C. elegans corepressors. Domain swapping identified two regions of POP-1 that are sufficient to confer nuclear asymmetry to human TCF4 when swapped with its corresponding domains. Despite undergoing Wnt-induced nuclear export, the human TCF4/POP-1 chimeric protein continues to function as a repressor for endoderm genes in E, a result we attribute to the inability of hTCF4 to bind to C. elegans ?-catenin. Our results reveal a higher degree of species specificity among TCF proteins for coactivator interactions than for corepressor interactions, and uncover a basic difference between how POP-1 and human TCF4 steady state nuclear levels are regulated. PMID:21539828

Robertson, Scott M.; Lo, Miao-Chia; Odom, Ranaan; Yang, Xiao-Dong; Medina, Jessica; Huang, Shuyi; Lin, Rueyling

2011-01-01

196

Corticosterone and pace of life in two life-history ecotypes of the garter snake Thamnophis elegans  

E-print Network

Corticosterone and pace of life in two life-history ecotypes of the garter snake Thamnophis elegans of the garter snake (Thamnophis elegans) that exhibit slow and fast pace of life strategies. We subjected free

Bronikowski, Anne

197

Metabolism, Body Size and Life Span: A Case Study in Evolutionarily Divergent Populations of the Garter Snake (Thamnophis elegans)  

E-print Network

of the Garter Snake (Thamnophis elegans) Anne Bronikowski1 and David Vleck Ecology, Evolution and Organismal of metabolism, life history and aging in the western terrestrial garter snake (Thamnophis elegans). Early

Bronikowski, Anne

198

The effects of maternal corticosterone levels on offspring behavior in fast-and slow-growth garter snakes (Thamnophis elegans)  

E-print Network

snakes (Thamnophis elegans) Kylie A. Robert 1 , Carol Vleck, Anne M. Bronikowski Department of Ecology of the resulting offspring. We treated pregnant female garter snakes (Thamnophis elegans) with low levels

Bronikowski, Anne

199

Identification of the varR Gene as a Transcriptional Regulator of Virginiamycin S Resistance in Streptomyces virginiae  

Microsoft Academic Search

A gene designated varR (for virginiae antibiotic resistance regulator) was identified in Streptomyces virginiae 89 bp downstream of a varS gene encoding a virginiamycin S (VS)-specific transporter. The deduced varR product showed high homology to repressors of the TetR family with a conserved helix-turn-helix DNA binding motif. Purified recombinant VarR protein was present as a dimer in vitro and showed

WISES NAMWAT; CHANG-KWON LEE; HIROSHI KINOSHITA; YASUHIRO YAMADA; TAKUYA NIHIRA

2001-01-01

200

Tumour-related microRNAs functions in Caenorhabditis elegans.  

PubMed

Altering cell proliferation and differentiation are usually key events leading to cancer. As originally demonstrated by Sydney Brenner in 1960s, the nematode Caenorhabditis elegans represents an animal model of choice to study mechanisms important to maintain proper cellular behaviour. This round worm has helped to elucidate components as well as new cellular pathways required for animal development. Among them, the discovery of the programmed cell death and non-coding RNAs (microRNAs) controlling gene expression are two remarkable examples. Recently, two studies have demonstrated, once again, that using C. elegans can help gathering insights on cellular mechanisms leading to tumour formation. Two microRNAs, miR-84 and miR-61, control the expression of the oncogene orthologues Ras and Vav indicating their capacity to act as tumour suppressors. These observations demonstrate that uncovering the function of microRNAs is important to increase our understanding of cancer. PMID:17028599

Jannot, G; Simard, M J

2006-10-01

201

Genome-Wide RNAi Longevity Screens in Caenorhabditis elegans  

PubMed Central

Progress in aging research has identified genetic and environmental factors that regulate longevity across species. The nematode worm Caenorhabditis elegans is a genetically tractable model system that has been widely used to investigate the molecular mechanisms of aging, and the development of RNA interference (RNAi) technology has provided a powerful tool for performing large-scale genetic screens in this organism. Genome-wide screens have identified hundreds of genes that influence lifespan, many of which fall into distinct functional classes and pathways. The purpose of this review is to summarize the results of large-scale RNAi longevity screens in C. elegans, and to provide an in-depth comparison and analysis of their methodology and most significant findings. PMID:23633911

Yanos, Melana E; Bennett, Christopher F; Kaeberlein, Matt

2012-01-01

202

Transcriptional Regulation of Gene Expression in C. elegans  

PubMed Central

Protein coding gene sequences are converted to mRNA by the highly regulated process of transcription. The precise temporal and spatial control of transcription for many genes is an essential part of development in metazoans. Thus, understanding the molecular mechanisms underlying transcriptional control is essential to understanding cell fate determination during embryogenesis, post-embryonic development, many environmental interactions, and disease-related processes. Studies of transcriptional regulation in C. elegans exploit its genomic simplicity and physical characteristics to define regulatory events with single cell and minute time scale resolution. When combined with the genetics of the system, C. elegans offers a unique and powerful vantage point from which to study how chromatin-associated protein and their modifications interact with transcription factors and their binding sites to yield precise control of gene expression through transcriptional regulation. PMID:23801596

Reinke, Valerie; Krause, Michael; Okkema, Peter

2013-01-01

203

Aging in the nervous system of Caenorhabditis elegans  

PubMed Central

It has recently been described that aging in C. elegans is accompanied by the progressive development of morphological changes in the nervous system. These include novel outgrowths from the cell body or axonal process, as well as blebbing and beading along the length of the axon. The formation of these structures is regulated by numerous molecular players including members of the well-conserved insulin/insulin growth factor-like (IGF)-1 signaling and mitogen-activated protein (MAP) kinase pathways. This review summarizes the recent literature on neuronal aging in C. elegans, including our own findings, which indicate a role for protein with tau-like repeats (PTL-1), the homolog of mammalian tau and MAP2/4, in maintaining neuronal integrity during aging. PMID:24255742

Chew, Yee Lian; Fan, Xiaochen; Götz, Jürgen; Nicholas, Hannah R.

2013-01-01

204

Aging. Lysosomal signaling molecules regulate longevity in Caenorhabditis elegans.  

PubMed

Lysosomes are crucial cellular organelles for human health that function in digestion and recycling of extracellular and intracellular macromolecules. We describe a signaling role for lysosomes that affects aging. In the worm Caenorhabditis elegans, the lysosomal acid lipase LIPL-4 triggered nuclear translocalization of a lysosomal lipid chaperone LBP-8, which promoted longevity by activating the nuclear hormone receptors NHR-49 and NHR-80. We used high-throughput metabolomic analysis to identify several lipids in which abundance was increased in worms constitutively overexpressing LIPL-4. Among them, oleoylethanolamide directly bound to LBP-8 and NHR-80 proteins, activated transcription of target genes of NHR-49 and NHR-80, and promoted longevity in C. elegans. These findings reveal a lysosome-to-nucleus signaling pathway that promotes longevity and suggest a function of lysosomes as signaling organelles in metazoans. PMID:25554789

Folick, Andrew; Oakley, Holly D; Yu, Yong; Armstrong, Eric H; Kumari, Manju; Sanor, Lucas; Moore, David D; Ortlund, Eric A; Zechner, Rudolf; Wang, Meng C

2015-01-01

205

The C. elegans healthspan and stress-resistance assay toolkit.  

PubMed

A wealth of knowledge on the genetic mechanisms that govern aging has emerged from the study of mutants that exhibit enhanced longevity and exceptional resilience to adverse environmental conditions. In these studies, lifespan has been an excellent proxy for establishing the rate of aging, but it is not always correlated with qualitative measures of healthy aging or 'healthspan'. Although the attributes of healthspan have been challenging to define, they share some universal features that are increasingly being incorporated into aging studies. Here we describe methods used to determine Caenorhabditis elegans healthspan. These include assessments of tissue integrity and functionality and resistance to a variety of biotic and abiotic stressors. We have chosen to include simple, rapid assays in this collection that can be easily undertaken in any C. elegans laboratory, and can be relied on to provide a preliminary but thorough insight into the healthspan of a population. PMID:24727065

Keith, Scott Alexander; Amrit, Francis Raj Gandhi; Ratnappan, Ramesh; Ghazi, Arjumand

2014-08-01

206

Direct measurements of drag forces in C. elegans crawling locomotion.  

PubMed

With a simple and versatile microcantilever-based force measurement technique, we have probed the drag forces involved in Caenorhabditis elegans locomotion. As a worm crawls on an agar surface, we found that substrate viscoelasticity introduces nonlinearities in the force-velocity relationships, yielding nonconstant drag coefficients that are not captured by original resistive force theory. A major contributing factor to these nonlinearities is the formation of a shallow groove on the agar surface. We measured both the adhesion forces that cause the worm's body to settle into the agar and the resulting dynamics of groove formation. Furthermore, we quantified the locomotive forces produced by C. elegans undulatory motions on a wet viscoelastic agar surface. We show that an extension of resistive force theory is able to use the dynamics of a nematode's body shape along with the measured drag coefficients to predict the forces generated by a crawling nematode. PMID:25418179

Rabets, Yegor; Backholm, Matilda; Dalnoki-Veress, Kari; Ryu, William S

2014-10-21

207

Noncanonical cell death in the nematode Caenorhabditis elegans  

PubMed Central

The nematode Caenorhabditis. elegans has served as a fruitful setting for cell death research for over three decades. A conserved pathway of four genes, egl-1/BH3-only, ced-9/Bcl-2, ced-4/Apaf-1, and ced-3/caspase, coordinates most developmental cell deaths in C. elegans. However, other cell death forms, programmed and pathological, have also been described in this animal. Some of these share morphological and/or molecular similarities with the canonical apoptotic pathway, while others do not. Indeed, recent studies suggest the existence of an entirely novel mode of programmed developmental cell destruction that may also be conserved beyond nematodes. Here we review evidence for these noncanonical pathways. We propose that different cell death modalities can function as backup mechanisms for apoptosis, or as tailor-made programs that allow specific dying cells to be efficiently cleared from the animal. PMID:25065890

Kinet, Maxime J.; Shaham, Shai

2014-01-01

208

Integrated control of protein degradation in C. elegans muscle  

PubMed Central

Protein degradation is a fundamental cellular process, the genomic control of which is incompletely understood. The advent of transgene-coded reporter proteins has enabled the development of C. elegans into a model for studying this problem. The regulation of muscle protein degradation is surprisingly complex, integrating multiple signals from hypodermis, intestine, neurons and muscle itself. Within the muscle, degradation is executed by separately regulated autophagy-lysosomal, ubiquitin-proteasome and calpain-mediated systems. The signal-transduction mechanisms, in some instances, involve modules previously identified for their roles in developmental processes, repurposed in terminally differentiated muscle to regulate the activities of pre-formed proteins. Here we review the genes, and mechanisms, which appear to coordinately control protein degradation within C. elegans muscle. We also consider these mechanisms in the context of development, physiology, pathophysiology and disease models. PMID:23457662

Lehmann, Susann; Shephard, Freya; Jacobson, Lewis A.; Szewczyk, Nathaniel J.

2012-01-01

209

Enhanced neuronal RNAi in C. elegans using SID-1  

PubMed Central

SUMMARY We expressed SID-1, a transmembrane protein from Caenorhabditis elegans that is required for systemic RNAi, in C. elegans neurons. This expression increased the response of neurons to dsRNA delivered by feeding. Mutations in the lin-15b and lin-35 genes further enhanced this effect. Worms expressing neuronal SID-1 showed RNAi phenotypes for known neuronal genes and for uncharacterized genes with no previously known neuronal phenotypes. Neuronal expression of sid-1 decreased non-neuronal RNAi, suggesting that neurons expressing transgenic sid-1(+) served as a sink for dsRNA. This effect, or a sid-1(?) background, can be used to uncover neuronal defects for lethal genes. Expression of sid-1(+) from cell-specific promoters in sid-1 mutants results in cell-specific feeding RNAi. We used these strains to identify a role for integrin signaling genes in mechanosensation. PMID:20512143

Calixto, Andrea; Chelur, Dattananda; Topalidou, Irini; Chen, Xiaoyin; Chalfie, Martin

2010-01-01

210

C. elegans as a model for membrane traffic  

PubMed Central

The counterbalancing action of the endocytosis and secretory pathways maintains a dynamic equilibrium that regulates the composition of the plasma membrane, allowing it to maintain homeostasis and to change rapidly in response to changes in the extracellular environment and/or intracellular metabolism. These pathways are intimately integrated with intercellular signaling systems and play critical roles in all cells. Studies in Caenorhabditis elegans have revealed diverse roles of membrane trafficking in physiology and development and have also provided molecular insight into the fundamental mechanisms that direct cargo sorting, vesicle budding, and membrane fisson and fusion. In this review, we summarize progress in understanding membrane trafficking mechanisms derived from work in C. elegans, focusing mainly on work done in non-neuronal cell-types, especially the germline, early embryo, coelomocytes, and intestine. PMID:24778088

Sato, Ken; Norris, Anne; Sato, Miyuki; Grant, Barth D.

2014-01-01

211

Optical interrogation of neural circuits in Caenorhabditis elegans  

PubMed Central

The nematode Caenorhabditis elegans has a compact nervous system with only 302 neurons. Whereas most of the synaptic connections between these neurons have been identified by electron microscopy serial reconstructions, functional connections have been inferred between only a few neurons through combinations of electrophysiology, cell ablation, in vivo calcium imaging and genetic analysis. To map functional connections between neurons, we combined in vivo optical stimulation with simultaneous calcium imaging. We analyzed the connections from the ASH sensory neurons and RIM interneurons to the command interneurons AVA and AVD. Stimulation of ASH or RIM neurons using channelrhodopsin-2 (ChR2) resulted in activation of AVA neurons, evoking an avoidance behavior. Our results demonstrate that we can excite specific neurons expressing ChR2 while simultaneously monitoring G-CaMP fluorescence in several other neurons, making it possible to rapidly decipher functional connections in C. elegans neural circuits. PMID:19898486

Guo, Zengcai V; Hart, Anne C; Ramanathan, Sharad

2011-01-01

212

Lettuce black root rot — a disease caused by Chalara elegans  

Microsoft Academic Search

Lettuce plants in several fields in south-eastern Queensland were affected by a black root rot resulting in slow growth, small\\u000a head size and harvest reductions. Isolation and pathogenicity tests showed Chalara elegans was the causal fungus. The host range included bean and cucurbits but not capsicum, celery, cotton, eggplant, parsley,\\u000a radish or tomato. The weed Sonchus oleraceus was a natural

R G. O’Brien

1994-01-01

213

Caenorhabditis elegans neuromuscular junction: GABA receptors and ivermectin action.  

PubMed

The prevalence of human and animal helminth infections remains staggeringly high, thus urging the need for concerted efforts towards this area of research. GABA receptors, encoded by the unc-49 gene, mediate body muscle inhibition in Caenorhabditis elegans and parasitic nematodes and are targets of anthelmintic drugs. Thus, the characterization of nematode GABA receptors provides a foundation for rational anti-parasitic drug design. We therefore explored UNC-49 channels from C. elegans muscle cultured cells of the first larval stage at the electrophysiological and behavioral levels. Whole-cell recordings reveal that GABA, muscimol and the anthelmintic piperazine elicit macroscopic currents from UNC-49 receptors that decay in their sustained presence, indicating full desensitization. Single-channel recordings show that all drugs elicit openings of ?2.5 pA (+100 mV), which appear either as brief isolated events or in short bursts. The comparison of the lowest concentration required for detectable channel opening, the frequency of openings and the amplitude of macroscopic currents suggest that piperazine is the least efficacious of the three drugs. Macroscopic and single-channel GABA-activated currents are profoundly and apparently irreversibly inhibited by ivermectin. To gain further insight into ivermectin action at C. elegans muscle, we analyzed its effect on single-channel activity of the levamisol-sensitive nicotinic receptor (L-AChR), the excitatory receptor involved in neuromuscular transmission. Ivermectin produces a profound inhibition of the frequency of channel opening without significant changes in channel properties. By revealing that ivermectin inhibits C. elegans muscle GABA and L-AChR receptors, our study adds two receptors to the already known ivermectin targets, thus contributing to the elucidation of its pleiotropic effects. Behavioral assays in worms show that ivermectin potentiates piperazine-induced paralysis, thus suggesting that their combination is a good strategy to overcome the increasing resistance of parasites, an issue of global concern for human and animal health. PMID:24743647

Hernando, Guillermina; Bouzat, Cecilia

2014-01-01

214

Analysis of Intraflagellar Transport in C. elegans Sensory Cilia  

Microsoft Academic Search

Cilia are assembled and maintained by intraflagellar transport (IFT), the motor-dependent, bidirectional movement of multiprotein complexes, called IFT particles, along the axoneme. The sensory cilia of Caenorhabditis elegans represent very useful objects for studying IFT because of the availability of in vivo time-lapse fluorescence microscopy assays of IFT and multiple ciliary mutants. In this system there are 60sensory neurons, each

Limin Hao; Seyda Acar; James Evans; Guangshuo Ou; Jonathan M. Scholey

2009-01-01

215

Neurotoxic effects of TDP-43 overexpression in C. elegans  

PubMed Central

RNA-binding protein TDP-43 has been associated with multiple neurodegenerative diseases, including amyotrophic lateral sclerosis and frontotemporal lobar dementia. We have engineered pan-neuronal expression of human TDP-43 protein in Caenorhabditis elegans, with the goal of generating a convenient in vivo model of TDP-43 function and neurotoxicity. Transgenic worms with the neuronal expression of human TDP-43 exhibit an ‘uncoordinated’ phenotype and have abnormal motorneuron synapses. Caenorhabditis elegans contains a single putative ortholog of TDP-43, designated TDP-1, which we show can support alternative splicing of CFTR in a cell-based assay. Neuronal overexpression of TDP-1 also results in an uncoordinated phenotype, while genetic deletion of the tdp-1 gene does not affect movement or alter motorneuron synapses. By using the uncoordinated phenotype as a read-out of TDP-43 overexpression neurotoxicty, we have investigated the contribution of specific TDP-43 domains and subcellular localization to toxicity. Full-length (wild-type) human TDP-43 expressed in C. elegans is localized to the nucleus. Deletion of either RNA recognition domain (RRM1 or RRM2) completely blocks neurotoxicity, as does deletion of the C-terminal region. These deleted TDP-43 variants still accumulate in the nucleus, although their subnuclear distribution is altered. Interestingly, fusion of TDP-1 C-terminal sequences to TDP-43 missing its C-terminal domain restores normal subnuclear localization and toxicity in C. elegans and CFTR splicing in cell-based assays. Overexpression of wild-type, full-length TDP-43 in mammalian cells (differentiated M17 cells) can also result in cell toxicity. Our results demonstrate that in vivo TDP-43 neurotoxicity can result from nuclear activity of overexpressed full-length protein. PMID:20530643

Ash, Peter E.A.; Zhang, Yong-Jie; Roberts, Christine M.; Saldi, Tassa; Hutter, Harald; Buratti, Emanuele; Petrucelli, Leonard; Link, Christopher D.

2010-01-01

216

The emergence of stereotyped behaviors in C. elegans  

Microsoft Academic Search

Many organisms, including humans, engage in stereotyped behaviors and these are often attributed to a deterministic command process within the nervous system. Here we use the locomotor dynamics of the nematode C. elegans to suggest an alternative explanation in which stereotyped behavior emerges due to noise within a non-linear dynamical system. In previous work (PLoS Comp Bio 4, e1000028 (2008))

Greg Stephens; William Ryu; William Bialek

2010-01-01

217

Imprinting Capacity of Gamete Lineages in Caenorhabditis elegans  

Microsoft Academic Search

We have observed a gamete-of-origin imprinting effect in C. elegans using a set of GFP reporter transgenes. From a single progenitor line carrying an extrachromosomal unc-54::gfp transgene array, we generated three independent autosomal integrations of the unc-54::gfp transgene. The progenitor line, two of its three integrated derivatives, and a nonrelated unc-119:gfp transgene exhibit an imprinting effect: single-genera- tion transmission of

Ky Sha; Andrew Fire

2005-01-01

218

The Meiotic Behavior of an Inversion in Caenorhabditis elegans  

Microsoft Academic Search

The rearrangement hZnl(Z) was isolated as a crossover suppressor for the right end of linkage group (LG) I. By inducing genetic markers on this crossover suppressor and establishing the gene order in the homozygote, hZnl(Z) was demonstrated to be the first genetically proven inversion in Caenorhabditis elegans. hZnl(1) extensively suppresses recombination in heterozygotes in the right arm of chromosome Z

Monique-Claire Zetka; Ann M. Rose

1992-01-01

219

Caenorhabditis elegans spermatozoan locomotion: amoeboid movement with almost no actin  

Microsoft Academic Search

The pseudopods of Caenorhabditis elegans spermatozoa move actively causing some cellsto translocatewhen the sperm are dissected into a low osmotic strength buffered saltssolution.On time-lapse video tapes, pseudopodial projectionscan be seen moving at20- 45 Am\\/min from the tipto the base of the pseudopod .This movement occurs whether or not the cellisattached to a substrate.Translocation of the cellisdependent on the substrate.Some spermatozoa

GREGORY A. NELSON; THOMAS M. ROBERTS; SAMUEL WARD

1982-01-01

220

Gene silencing in Caenorhabditis elegans by transitive RNA interference  

Microsoft Academic Search

When a cell is exposed to double-stranded RNA (dsRNA), mRNA from the homologous gene is selectively degraded by a process called RNA interference (RNAi). Here, we provide evidence that dsRNA is amplified in Caenorhabditis elegans to ensure a robust RNAi response. Our data suggest a model in which mRNA targeted by RNAi functions as a template for 5 to 3

MATTHEW N. ALDER; SHALE DAMES; JEFFREY GAUDET; SUSAN E. MANGO

2003-01-01

221

C. elegans: a model system for systems neuroscience  

PubMed Central

Summary The nematode C. elegans is an excellent model organism for a systems-level understanding of neural circuits and behavior. Advances in the quantitative analyses of behavior and neuronal activity, and the development of new technologies to precisely control and monitor the workings of interconnected circuits, now allow investigations into the molecular, cellular and systems-level strategies that transform sensory inputs into precise behavioral outcomes. PMID:19896359

Sengupta, Piali; Samuel, Aravinthan D.T.

2009-01-01

222

Reductive stress on life span extension in C. elegans  

Microsoft Academic Search

Recently, Schulz and colleagues have contributed to the ongoing controversy on the unproven role of oxidative stress in the aging process in their well-performed study 'Glucose restriction extends Caenorhabditis elegans life span by inducing mitochondrial respiration and increasing oxidative stress' (Cell Metab 2007, 6: 280–293). Here, we suggest an alternative hypothesis that reductive stress can prevent calorie-restriction induced life span

Markus Ralser; Ivor J Benjamin

2008-01-01

223

Spaceflight and ageing: reflecting on Caenorhabditis elegans in space.  

PubMed

The prospect of space travel continues to capture the imagination. Several competing companies are now promising flights for the general population. Previously, it was recognized that many of the physiological changes that occur with spaceflight are similar to those seen with normal ageing. This led to the notion that spaceflight can be used as a model of accelerated ageing and raised concerns about the safety of individuals engaging in space travel. Paradoxically, however, space travel has been recently shown to be beneficial to some aspects of muscle health in the tiny worm Caenorhabditis elegans. C. elegans is a commonly used laboratory animal for studying ageing. C. elegans displays age-related decline of some biological processes observed in ageing humans, and about 35% of C. elegans' genes have human homologs. Space flown worms were found to have decreased expression of a number of genes that increase lifespan when expressed at lower levels. These changes were accompanied by decreased accumulation of toxic protein aggregates in ageing worms' muscles. Thus, in addition to spaceflight producing physiological changes that are similar to accelerated ageing, it also appears to produce some changes similar to delayed ageing. Here, we put forward the hypothesis that in addition to the previously well-appreciated mechanotransduction changes, neural and endocrine signals are altered in response to spaceflight and that these may have both negative (e.g. less muscle protein) and some positive consequences (e.g. healthier muscles), at least for invertebrates, with respect to health in space. Given that changes in circulating hormones are well documented with age and in astronauts, our view is that further research into the relationship between metabolic control, ageing, and adaptation to the environment should be productive in advancing our understanding of the physiology of both spaceflight and ageing. PMID:24217152

Honda, Yoko; Honda, Shuji; Narici, Marco; Szewczyk, Nathaniel J

2014-01-01

224

Genomic Analysis of Stress Response against Arsenic in Caenorhabditis elegans  

PubMed Central

Arsenic, a known human carcinogen, is widely distributed around the world and found in particularly high concentrations in certain regions including Southwestern US, Eastern Europe, India, China, Taiwan and Mexico. Chronic arsenic poisoning affects millions of people worldwide and is associated with increased risk of many diseases including arthrosclerosis, diabetes and cancer. In this study, we explored genome level global responses to high and low levels of arsenic exposure in Caenorhabditis elegans using Affymetrix expression microarrays. This experimental design allows us to do microarray analysis of dose-response relationships of global gene expression patterns. High dose (0.03%) exposure caused stronger global gene expression changes in comparison with low dose (0.003%) exposure, suggesting a positive dose-response correlation. Biological processes such as oxidative stress, and iron metabolism, which were previously reported to be involved in arsenic toxicity studies using cultured cells, experimental animals, and humans, were found to be affected in C. elegans. We performed genome-wide gene expression comparisons between our microarray data and publicly available C. elegans microarray datasets of cadmium, and sediment exposure samples of German rivers Rhine and Elbe. Bioinformatics analysis of arsenic-responsive regulatory networks were done using FastMEDUSA program. FastMEDUSA analysis identified cancer-related genes, particularly genes associated with leukemia, such as dnj-11, which encodes a protein orthologous to the mammalian ZRF1/MIDA1/MPP11/DNAJC2 family of ribosome-associated molecular chaperones. We analyzed the protective functions of several of the identified genes using RNAi. Our study indicates that C. elegans could be a substitute model to study the mechanism of metal toxicity using high-throughput expression data and bioinformatics tools such as FastMEDUSA. PMID:23894281

Sahu, Surasri N.; Lewis, Jada; Patel, Isha; Bozdag, Serdar; Lee, Jeong H.; Sprando, Robert; Cinar, Hediye Nese

2013-01-01

225

Gene expression and development databases for C. elegans  

Microsoft Academic Search

The nematode wormC. elegans, with its transparent body, is an excellent vehicle for studying developmental gene expression during embryogenesis and throughout its short life. Expression data from in-situ hybridization, immunolocalization and reporter constructs have been put into the ACeDB database, which is used to store and disseminate most types ofC. elegansdata, and is also widely used for genome-sequencing projects. In

Sylvia D. Martinelli; Clive G. Brown; Richard Durbin

1997-01-01

226

Caenorhabditis elegans Innate Immune Response Triggered by Salmonella enterica Requires Intact LPS and Is Mediated by a MAPK Signaling Pathway  

Microsoft Academic Search

Compared to mammals, insects, and plants, relatively little is known about innate immune responses in the nematode Caenorhabditis elegans. Previous work showed that Salmonella enterica serovars cause a persistent infection in the C. elegans intestine [1, 2] that triggers gonadal programmed cell death (PCD) and that C. elegans cell death (ced) mutants are more susceptible to Salmonella-mediated killing [3]. To

Alejandro Aballay; Eliana Drenkard; Layla R. Hilbun; Frederick M. Ausubel

2003-01-01

227

Evidence for Selection on Thermoregulation: Effects of Temperature on Embryo Mortality in the Garter Snake Thamnophis elegans  

E-print Network

in the Garter Snake Thamnophis elegans RYAN P. O'DONNELL AND STEVAN J. ARNOLD Despite widespread belief-four female Thamnophis elegans were maintained at one of nine constant temperatures during pregnancy (21­33 C snake Thamnophis elegans. Two studies found evidence for the effects of thermoregulation on fitness

Arnold, Stevan J.

228

Adaptive divergence within and between ecotypes of the terrestrial garter snake, Thamnophis elegans, assessed with FST-QST  

E-print Network

Adaptive divergence within and between ecotypes of the terrestrial garter snake, Thamnophis elegans study system, populations of the terrestrial garter snake (Thamnophis elegans) in the Eagle Lake basin-statistics; scalation. Abstract Populations of the terrestrial garter snake (Thamnophis elegans) around Eagle Lake

Palumbi, Stephen

229

A genetic linkage map for watermelon derived from a testcross population: ( Citrullus lanatus var. citroides × C. lanatus var. lanatus ) × Citrullus colocynthis  

Microsoft Academic Search

A genetic linkage map was constructed for watermelon using a testcross population [Plant Accession Griffin 14113 (Citrullus lanatus var. citroides) 2 New Hampshire Midget (NHM; C. lanatus var. lanatus)] 2 U.S. Plant Introduction (PI) 386015 (Citrullus colocynthis). The map contains 141 randomly amplified polymorphic DNA (RAPD) markers produced by 78 primers, 27 inter-simple sequence repeat (ISSR) markers produced by 17

A. Levi; C. Thomas; T. Joobeur; X. Zhang; A. Davis

2002-01-01

230

Goalpha regulates volatile anesthetic action in Caenorhabditis elegans.  

PubMed Central

To identify genes controlling volatile anesthetic (VA) action, we have screened through existing Caenorhabditis elegans mutants and found that strains with a reduction in Go signaling are VA resistant. Loss-of-function mutants of the gene goa-1, which codes for the alpha-subunit of Go, have EC(50)s for the VA isoflurane of 1.7- to 2.4-fold that of wild type. Strains overexpressing egl-10, which codes for an RGS protein negatively regulating goa-1, are also isoflurane resistant. However, sensitivity to halothane, a structurally distinct VA, is differentially affected by Go pathway mutants. The RGS overexpressing strains, a goa-1 missense mutant found to carry a novel mutation near the GTP-binding domain, and eat-16(rf) mutants, which suppress goa-1(gf) mutations, are all halothane resistant; goa-1(null) mutants have wild-type sensitivities. Double mutant strains carrying mutations in both goa-1 and unc-64, which codes for a neuronal syntaxin previously found to regulate VA sensitivity, show that the syntaxin mutant phenotypes depend in part on goa-1 expression. Pharmacological assays using the cholinesterase inhibitor aldicarb suggest that VAs and GOA-1 similarly downregulate cholinergic neurotransmitter release in C. elegans. Thus, the mechanism of action of VAs in C. elegans is regulated by Goalpha, and presynaptic Goalpha-effectors are candidate VA molecular targets. PMID:11404329

van Swinderen, B; Metz, L B; Shebester, L D; Mendel, J E; Sternberg, P W; Crowder, C M

2001-01-01

231

Specioside ameliorates oxidative stress and promotes longevity in Caenorhabditis elegans.  

PubMed

Specioside (6-O-coumaroylcatalpol) is an iridoid glucoside which possesses multifunctional activities viz. analgesic, antidyspeptic, astringent, liver stimulating and wound healing properties. The present study for the first time delineates stress alleviating and lifespan prolonging action of specioside (SPC), isolated from Stereospermum suaveolens in the free living, multicellular nematode model Caenorhabditis elegans. A strong correlation between lifespan extension and stress modulation in adult worms was established in a dose dependent manner. The dietary intake of this phytomolecule elevated juglone induced oxidative and heat induced thermal stress tolerance in C. elegans. On evaluation, it was found that 25?M dose of SPC significantly extended lifespan by 15.47% (P?0.0001) with reduction in stress level. Furthermore, SPC enhanced mean survival in mev-1 mutant suggesting its oxidative stress reducing potential. Furthermore, SPC augmented stress modulatory enzymes superoxide dismutase (SOD) and catalase (CAT) level in C. elegans. Altogether, these findings broaden current perspectives concerning stress alleviating potentials of SPC and have implications in development of therapeutics for curing age related disorders. PMID:25619942

Asthana, Jyotsna; Yadav, A K; Pant, Aakanksha; Pandey, Swapnil; Gupta, M M; Pandey, Rakesh

2015-03-01

232

Introduction to Germ Cell Development in C. elegans  

PubMed Central

A central feature of the continuum of life in sexually reproducing metazoans is the cycle of the germline from one generation to the next. This volume describes the cycle of the germline for Caenorhabditis elegans, through chapters that are focused on distinct aspects or processes in germ cell development. Topics include sequential and dependent processes such as specification of germ cells as distinct from somatic cells, sex determination, stem cell proliferative fate versus meiotic development decision, recombination/ progression through meiotic prophase, contemporaneous processes such as gametogenesis, meiotic development and apoptosis, and continuing the cycle into the next generation through fertilization and the oocyte-to-embryo-transition. Throughout germ cell development, translational control and epigenetic mechanisms play prominent roles. These different aspects of germ cell development are seamlessly integrated under optimal conditions and are modified in the different reproductive strategies that are employed by C. elegans under harsh environmental conditions. In this chapter we set the stage by providing a brief background on the C. elegans system and germ cell development, indicating processes in the cycle of the germline that are covered in each chapter. PMID:22872472

Pazdernik, Nanette; Schedl, Tim

2013-01-01

233

Exposure to Mitochondrial Genotoxins and Dopaminergic Neurodegeneration in Caenorhabditis elegans  

PubMed Central

Neurodegeneration has been correlated with mitochondrial DNA (mtDNA) damage and exposure to environmental toxins, but causation is unclear. We investigated the ability of several known environmental genotoxins and neurotoxins to cause mtDNA damage, mtDNA depletion, and neurodegeneration in Caenorhabditis elegans. We found that paraquat, cadmium chloride and aflatoxin B1 caused more mitochondrial than nuclear DNA damage, and paraquat and aflatoxin B1 also caused dopaminergic neurodegeneration. 6-hydroxydopamine (6-OHDA) caused similar levels of mitochondrial and nuclear DNA damage. To further test whether the neurodegeneration could be attributed to the observed mtDNA damage, C. elegans were exposed to repeated low-dose ultraviolet C radiation (UVC) that resulted in persistent mtDNA damage; this exposure also resulted in dopaminergic neurodegeneration. Damage to GABAergic neurons and pharyngeal muscle cells was not detected. We also found that fasting at the first larval stage was protective in dopaminergic neurons against 6-OHDA-induced neurodegeneration. Finally, we found that dopaminergic neurons in C. elegans are capable of regeneration after laser surgery. Our findings are consistent with a causal role for mitochondrial DNA damage in neurodegeneration, but also support non mtDNA-mediated mechanisms. PMID:25486066

Bodhicharla, Rakesh K.; McKeever, Madeline G.; Arrant, Andrew E.; Margillo, Kathleen M.; Ryde, Ian T.; Cyr, Derek D.; Kosmaczewski, Sara G.; Hammarlund, Marc; Meyer, Joel N.

2014-01-01

234

Regulation of Caenorhabditis elegans and Pseudomonas aeruginosa machinery during interactions.  

PubMed

The amenability of Caenorhabditis elegans against pathogen provides a valuable tool for studying host-pathogen interactions. Physiological experiments revealed that the P. aeruginosa was able to kill C. elegans efficiently. The effects of P. aeruginosa PA14, PAO1 and their isolated lipopolysaccharide (LPS) on the host system were analyzed. The LPS at higher concentrations (?2 mg/ml) was toxic to the host animals. Kinetic studies using qPCR revealed the regulation of host-specific candidate antimicrobial genes during pathogen-mediated infections. In addition, the pathogen-specific virulent gene, exoT expression, was anlyzed and found to be varied during the interactions with the host system. Ability of the pathogens to modify their internal machinery in the presence of the host was analyzed by XRD, FTIR and PCA. LPS isolated from pathogens upon exposure to C. elegans showed modifications at their functional regions. LPS from PAO1 showed difference in d-spacing angle (?) and °2Th position. FTIR spectra revealed alterations in polysaccharide (1,200-900 cm(-1)) and fatty acid (3,000-2,800 cm(-1)) regions of LPS from P. aeruginosa PAO1 exposed to the host system. These data provide additional insights on how the pathogens subvert its own and host machinery during interactions. PMID:21909805

Vigneshkumar, Balasubramanian; Pandian, Shunmugiah Karutha; Balamurugan, Krishnaswamy

2012-04-01

235

Direct micro-mechanical measurements on C. elegans  

NASA Astrophysics Data System (ADS)

The millimeter-sized nematode Caenorhabditis elegans provides an excellent biophysical system for both static and dynamic biomechanical studies. The undulatory motion exhibited by this model organism as it crawls or swims through a medium is ubiquitous in nature at scales from microns to meters. A successful description of this form of locomotion requires knowledge of the material properties of the crawler, as well as its force output as it moves. Here we present an experimental technique with which the material properties and dynamics of C. elegans can be directly probed. By using the deflection of a flexible micropipette, the bending stiffness of C. elegans has been measured at all stages of its life cycle, as well as along the body of the adult worm. The mechanical properties of the worm are modelled as a viscoelastic material which provides new insights into its material properties. The forces exerted by the worm during undulatory motion are also discussed. Direct experimental characterization of this model organism provides guidance for theoretical treatments of undulatory locomotion in general.

Backholm, Matilda; Ryu, William S.; Dalnoki-Veress, Kari

2013-03-01

236

Black Tea Increased Survival of Caenorhabditis elegans under Stress.  

PubMed

The present study examined the effects of black tea (Camellia sinensis) extracts (BTE) in Caenorhabditis elegans under various abiotic stressors. Results showed BTE increased nematode resistance to osmosis, heat, and UV irradiation treatments. However, BTE could not increase nematodes' lifespan under normal culture conditions and MnCl2-induced toxicity at concentrations we used. Further studies showed that BTE decreased reactive oxygen species and up-regulated some antioxidant enzymes, including GSH-PX, and genes, such as gsh-px and sod-3. However, only a slight extension in mev-1 mutants mean lifespan was observed without significance. These results indicated that the antioxidant activity of BTE might be necessary but not sufficient to protect against aging to C. elegans. Moreover, BTE increased the mRNA level of stress-response genes such as sir-2.1 and sek-1. Our finding demonstrated BTE might increase heat and UV stress resistance in a sir.2.1-dependent manner. Taken together, BTE enhanced stress resistance with multiple mechanisms in C. elegans. PMID:25345740

Xiong, Li-Gui; Huang, Jian-An; Li, Juan; Yu, Peng-Hui; Xiong, Zhe; Zhang, Jian-Wei; Gong, Yu-Shun; Liu, Zhong-Hua; Chen, Jin-Hua

2014-11-19

237

Temporal Dynamics and Linkage Disequilibrium in Natural Caenorhabditis elegans Populations  

PubMed Central

Caenorhabditis elegans is a major laboratory model system yet a newcomer to the field of population genetics, and relatively little is known of its biology in the wild. Recent studies of natural populations at a single time point revealed strong spatial population structure and suggested that these populations may be very dynamic. We have therefore studied several natural C. elegans populations over time and genotyped them at polymorphic microsatellite loci. While some populations appear to be genetically stable over the course of observation, others seem to go extinct, with full replacement of multilocus genotypes upon regrowth. The frequency of heterozygotes indicates that outcrossing occurs at a mean frequency of 1.7% and is variable between populations. However, in genetically stable populations, linkage disequilibrium between different chromosomes can be maintained over several years at a level much higher than expected from the heterozygote frequency. C. elegans seems to follow metapopulation dynamics, and the maintenance of linkage disequilibrium despite a low yet significant level of outcrossing suggests that selection may act against the progeny of outcrossings. PMID:17409084

Barrière, Antoine; Félix, Marie-Anne

2007-01-01

238

Transposition of Tc1 in the nematode Caenorhabditis elegans.  

PubMed

We have identified a strain of Caenorhabditis elegans in which the transposable element Tc1 is genetically active. Most spontaneous mutations affecting the unc-54 myosin heavy chain gene of C. elegans variety Bergerac are due to insertions of Tc1 within unc-54. The Bergerac genome contains an unusually high number of Tc1 elements, but this is not responsible for transpositional activity. Another variety of C. elegans, strain DH424, contains an equally high number of Tc1 elements, but transpositions are not detected. Tc1 insertion mutations are genetically unstable. They revert to unc-54+ in both germ-line and somatic cells. Germ-line revertants are wild type and contain precise or nearly precise excisions of Tc1. Somatic revertants are genetic mosaics; they contain small patches of revertant muscle tissue in otherwise mutant animals. The pattern of mosaicism often allows us to know when and where during muscle development the excisions occur. Somatic reversion can be over 1000-fold more frequent than germ-line reversion. PMID:2984668

Eide, D; Anderson, P

1985-03-01

239

Optical reversal of halothane-induced immobility in C. elegans  

PubMed Central

Summary Volatile anesthetics (VAs) cause profound neurological effects, including reversible loss of consciousness and immobility. Despite their widespread use, the mechanism of action of VAs remains one of the unsolved puzzles of neuroscience [1,2]. Genetic studies in C. elegans [3, 4], Drosophila [3,5], and mice [6–9] indicate that ion channels controlling the neuronal resting membrane potential (RMP) also control anesthetic sensitivity. Leak channels selective for K+ [10–13] or permeable to Na+ [14], are critical for establishing RMP. We hypothesized that halothane, a VA, caused immobility by altering the neuronal RMP. In C. elegans, halothane induced immobility is acutely and completely reversed by channelrhodopsin-2 based depolarization of the RMP when expressed specifically in cholinergic neurons. Furthermore, hyperpolarizing cholinergic neurons via halorhodopsin activation increases sensitivity to halothane. The sensitivity of C. elegans to halothane can be altered by 25-fold by either manipulation of membrane conductance with optogenetic methods or generation of mutations in leak channels that set the RMP. Immobility induced by another VA, isoflurane, is not affected by these treatments, thereby excluding the possibility of non-specific hyperactivity. The sum of our data indicates that leak channels and the RMP are important determinants of halothane-induced general anesthesia. PMID:22137475

Singaram, Vinod K.; Somerlot, Benjamin H.; Falk, Scott A.; Falk, Marni J.; Sedensky, Margaret M.; Morgan, Philip G.

2011-01-01

240

Intracellular protein glycosylation modulates insulin mediated lifespan in C. elegans  

PubMed Central

O-linked-?-N-acetylglucosamine (O-GlcNAc) modification is a regulatory, nuclear and cytoplasmic post-translational glycosylation of proteins associated with age-related diseases such as Alzheimer's, Parkinson's, and type II diabetes. Global elevation of O-GlcNAc levels on intracellular proteins can induce insulin resistance, the hallmark of type II diabetes, in mammalian systems. In C. elegans, attenuation of the insulin-like signal transduction pathway increases adult lifespan of the nematode. We demonstrate that the O-GlcNAc cycling enzymes OGT and OGA, which add and remove O-GlcNAc respectively, modulate lifespan in C. elegans. Median adult lifespan is increased in an oga-1 deletion strain while median adult life span is decreased upon ogt-1 deletion. The O-GlcNAc-mediated effect on nematode lifespan is dependent on the FoxO transcription factor DAF-16. DAF-16 is a key factor in the insulin-like signal transduction pathway to regulate reproductive development, lifespan, stress tolerance, and dauer formation in C. elegans. Our data indicates that O-GlcNAc cycling selectively influences only a subset of DAF-16 mediated phenotypes, including lifespan and oxidative stress resistance. We performed an affinity purification of O-GlcNAc-modified proteins and observed that a high percentage of these proteins are regulated by insulin signaling and/or impact insulin pathway functional outcomes, suggesting that the O-GlcNAc modification may control downstream effectors to modulate insulin pathway mediated cellular processes. PMID:20952811

Rahman, Mohammad M.; Stuchlick, Olga; El-Karim, Enas G.; Stuart, Ryan; Kipreos, Edward T.; Wells, Lance

2010-01-01

241

Biomechanical analysis of gait adaptation in the nematode Caenorhabditis elegans.  

PubMed

To navigate different environments, an animal must be able to adapt its locomotory gait to its physical surroundings. The nematode Caenorhabditis elegans, between swimming in water and crawling on surfaces, adapts its locomotory gait to surroundings that impose approximately 10,000-fold differences in mechanical resistance. Here we investigate this feat by studying the undulatory movements of C. elegans in Newtonian fluids spanning nearly five orders of magnitude in viscosity. In these fluids, the worm undulatory gait varies continuously with changes in external load: As load increases, both wavelength and frequency of undulation decrease. We also quantify the internal viscoelastic properties of the worm's body and their role in locomotory dynamics. We incorporate muscle activity, internal load, and external load into a biomechanical model of locomotion and show that (i) muscle power is nearly constant across changes in locomotory gait, and (ii) the onset of gait adaptation occurs as external load becomes comparable to internal load. During the swimming gait, which is evoked by small external loads, muscle power is primarily devoted to bending the worm's elastic body. During the crawling gait, evoked by large external loads, comparable muscle power is used to drive the external load and the elastic body. Our results suggest that C. elegans locomotory gait continuously adapts to external mechanical load in order to maintain propulsive thrust. PMID:21048086

Fang-Yen, Christopher; Wyart, Matthieu; Xie, Julie; Kawai, Risa; Kodger, Tom; Chen, Sway; Wen, Quan; Samuel, Aravinthan D T

2010-11-23

242

Aluminium exposure disrupts elemental homeostasis in Caenorhabditis elegans†  

PubMed Central

Aluminium (Al) is highly abundant in the environment and can elicit a variety of toxic responses in biological systems. Here we characterize the effects of Al on Caenorhabditis elegans by identifying phenotypic abnormalities and disruption in whole-body metal homeostasis (metallostasis) following Al exposure in food. Widespread changes to the elemental content of adult nematodes were observed when chronically exposed to Al from the first larval stage (L1). Specifically, we saw increased barium, chromium, copper and iron content, and a reduction in calcium levels. Lifespan was decreased in worms exposed to low levels of Al, but unexpectedly increased when the Al concentration reached higher levels (4.8 mM). This bi-phasic phenotype was only observed when Al exposure occurred during development, as lifespan was unaffected by Al exposure during adulthood. Lower levels of Al slowed C. elegans developmental progression, and reduced hermaphrodite self-fertility and adult body size. Significant developmental delay was observed even when Al exposure was restricted to embryogenesis. Similar changes in Al have been noted in association with Al toxicity in humans and other mammals, suggesting that C. elegans may be of use as a model for understanding the mechanisms of Al toxicity in mammalian systems. PMID:22534883

Page, Kathryn E.; White, Keith N.; McCrohan, Catherine R.

2013-01-01

243

Dopamine modulates the plasticity of mechanosensory responses in Caenorhabditis elegans  

PubMed Central

Dopamine-modulated behaviors, including information processing and reward, are subject to behavioral plasticity. Disruption of these behaviors is thought to support drug addictions and psychoses. The plasticity of dopamine-mediated behaviors, for example, habituation and sensitization, are not well understood at the molecular level. We show that in the nematode Caenorhabditis elegans, a D1-like dopamine receptor gene (dop-1) modulates the plasticity of mechanosensory behaviors in which dopamine had not been implicated previously. A mutant of dop-1 displayed faster habituation to nonlocalized mechanical stimulation. This phenotype was rescued by the introduction of a wild-type copy of the gene. The dop-1 gene is expressed in mechanosensory neurons, particularly the ALM and PLM neurons. Selective expression of the dop-1 gene in mechanosensory neurons using the mec-7 promoter rescues the mechanosensory deficit in dop-1 mutant animals. The tyrosine hydroxylase-deficient C. elegans mutant (cat-2) also displays these specific behavioral deficits. These observations provide genetic evidence that dopamine signaling modulates behavioral plasticity in C. elegans. PMID:14739932

Sanyal, Suparna; Wintle, Richard F; Kindt, Katie S; Nuttley, William M; Arvan, Rokhand; Fitzmaurice, Paul; Bigras, Eve; Merz, David C; Hébert, Terence E; van der Kooy, Derek; Schafer, William R; Culotti, Joseph G; Van Tol, Hubert H M

2004-01-01

244

Methods to assess subcellular compartments of muscle in C. elegans.  

PubMed

Muscle is a dynamic tissue that responds to changes in nutrition, exercise, and disease state. The loss of muscle mass and function with disease and age are significant public health burdens. We currently understand little about the genetic regulation of muscle health with disease or age. The nematode C. elegans is an established model for understanding the genomic regulation of biological processes of interest. This worm's body wall muscles display a large degree of homology with the muscles of higher metazoan species. Since C. elegans is a transparent organism, the localization of GFP to mitochondria and sarcomeres allows visualization of these structures in vivo. Similarly, feeding animals cationic dyes, which accumulate based on the existence of a mitochondrial membrane potential, allows the assessment of mitochondrial function in vivo. These methods, as well as assessment of muscle protein homeostasis, are combined with assessment of whole animal muscle function, in the form of movement assays, to allow correlation of sub-cellular defects with functional measures of muscle performance. Thus, C. elegans provides a powerful platform with which to assess the impact of mutations, gene knockdown, and/or chemical compounds upon muscle structure and function. Lastly, as GFP, cationic dyes, and movement assays are assessed non-invasively, prospective studies of muscle structure and function can be conducted across the whole life course and this at present cannot be easily investigated in vivo in any other organism. PMID:25489753

Gaffney, Christopher J; Bass, Joseph J; Barratt, Thomas F; Szewczyk, Nathaniel J

2014-01-01

245

Mating Damages the Cuticle of C. elegans Hermaphrodites  

PubMed Central

Lifespan costs to reproduction are common across multiple species, and such costs could potentially arise through a number of mechanisms. In the nematode Caenorhabditis elegans, it has been suggested that part of the lifespan cost to hermaphrodites from mating results from physical damage owing to the act of copulation itself. Here, we examine whether mating damages the surface of the hermaphrodite cuticle via scanning electron microscopy. It is found that mated hermaphrodites suffered delamination of cuticle layers surrounding the vulva, and that the incidence of such damage depends on genetic background. Unmated hermaphrodites demonstrated almost no such damage, even when cultured in soil with potentially abrasive particles. Thus, a consequence of mating for C. elegans hermaphrodites is physical cuticle damage. These experiments did not assess the consequences of cuticle damage for lifespan, and the biological significance of this damage remains unclear. We further discuss our results within the context of recent studies linking the lifespan cost to mating in C. elegans hermaphrodites to male secretions. PMID:25105881

Woodruff, Gavin C.; Knauss, Christine M.; Maugel, Timothy K.; Haag, Eric S.

2014-01-01

246

Micropropagation of the Rare Lakeside Daisy (Hymenoxys acaulis var. glabra)  

Microsoft Academic Search

Shoot tip and stem segment explants collected from greenhouse-maintained plants of Hymenoxys acaulis var. glabra were cultured in vitro for shoot initiation on a Murashige and Skoog (MS) medium supplemented with 30 g·L -1 sucrose, 2.5 µM BA, and 7 g·L -1 agar at a pH of 5.7. Unbranched shoot explants were subcultured to MS medium with 0.0, 0.5, 1,

James R. Ault

247

TAXES AND ECONOMIC GROWTH IN ROMANIA. A VAR APPROACH  

Microsoft Academic Search

The paper analyzes the relationship between taxes and economic growth in the case ofRomania in the period January 1999 - March 2010, using an unrestricted Vector AutoregressionModel (VAR) based on the rate of dynamic taxation’s level and the rate of dynamic economic growth.The relationship is questioned in both directions, namely with reference to the manner in which taxesaffect economic growth,

Mihai Ioan Mutascu; Dan Constantin Danuletiu

2011-01-01

248

New lignans from the heartwood of Chamaecyparis obtusa var. formosana.  

PubMed

Four new lignans, 3',4'-O,O-demethylenehinokinin (1), chamalignolide (2), 8'beta-hydroxyhinokinin (3) and 7beta,8beta-epoxyzuonin A (4), as well as (-)-hinokinin (5), and (-)-zuonin A (6), were isolated from the heartwood of Chamaecyparis obtusa var. formosana. The structures of these lignans were unambiguously determined by spectroscopic methods. And the absolute configuration of 1 was elucidated with a circular dichroism (CD) spectrum. PMID:12130860

Kuo, Yueh-Hsiung; Chen, Chia-Hsien; Lin, Yun-Lian

2002-07-01

249

Capacitor-Less VAR Compensator Based on a Matrix Converter  

E-print Network

: Chair of Committee, Robert S. Balog Committee Members, Hamid Toliyat Shankar Bhattacharyya Won-jong Kim Head of Department, Costas Georghiades December 2010 Major Subject: Electrical Engineering iii ABSTRACT Capacitor-Less VAR... things I have learnt during the course of my work. My sincere thanks are due to Dr. Hamid Toliyat, Dr. Shankar Bhattacharyya and Dr. Won-jong Kim for sparing their valuable time to serve on my defense committee. I would also like to thank Dr. Prasad...

Balakrishnan, Divya Rathna

2012-02-14

250

Sesquiterpenes from the leaves of Ligularia fischeri var. spiciformis.  

PubMed

From the leaves of Ligularia fischeri var. spiciformis, a new eremophilanolide, 8 alpha-methoxy-6-oxoeremophil-7(11)-en-12,8-olide (6-oxoeremophilenolide) and a eudesmane-type sesquiterpene, (+)-intermedeol were isolated. The structures were determined on the basis of 2D-NMR spectral data. Data on cytotoxicity showed that the latter was clearly more potent than the former compound. PMID:11199147

Park, H J; Kwon, S H; Yoo, K O; Sohn, I C; Lee, K T; Lee, H K

2000-12-01

251

Modelling factor demands with SEM and VAR: an empirical comparison  

Microsoft Academic Search

The empirical analysis of the economic interactions between factors of production, output and corresponding prices has received\\u000a much attention over the last two decades. Most contributions in this area have agreed on the neoclassical principle of a representative\\u000a optimizing firm and typically use theory-based structural equation models (SEM). A popular alternative to SEM is the vector\\u000a autoregression (VAR) methodology. The

Matteo Manera

2006-01-01

252

LETTER TO THE EDITOR Oligonucleotide-based targeted gene editing in C. elegans  

E-print Network

LETTER TO THE EDITOR Oligonucleotide-based targeted gene editing in C. elegans via the CRISPR/Cas9 Repeats (CRISPR)/ CRISPR-associated (Cas) system has emerged as a new powerful tool for genome [6], C. elegans [7-12], and plants [13]. In the widely used CRISPR/Cas9 system [2-4], the Cas9

Xue, Ding

253

Identification of two epoxide hydrolases in Caenorhabditis elegans that metabolize mammalian lipid signaling molecules  

E-print Network

Identification of two epoxide hydrolases in Caenorhabditis elegans that metabolize mammalian lipidEH has been implicated in the metabolism of several epoxide-con- taining lipid signaling molecules [7 of possible lipid signaling molecules in C. elegans. Ã? 2008 Elsevier Inc. All rights reserved. Keywords

Hammock, Bruce D.

254

Resistance to Bacillus thuringiensis Toxin in Caenorhabditis elegans from Loss of Fucose*  

E-print Network

Resistance to Bacillus thuringiensis Toxin in Caenorhabditis elegans from Loss of Fucose* Received elegans bre-1 gene was iso- lated in a screen for Bacillus thuringiensis toxin-resistant (bre) mutants by Bacillus thuringiensis are naturally occurring agents that are used for the control of insects that eat

Aroian, Raffi V.

255

C. elegans HAM-1 positions the cleavage plane and regulates apoptosis in asymmetric neuroblast divisions  

E-print Network

C. elegans HAM-1 positions the cleavage plane and regulates apoptosis in asymmetric neuroblast generate neurons, neural support cells and apoptotic cells. C. elegans HAM-1 is an asymmetrically that HAM-1 is a novel protein and define residues important for HAM-1 function and distribution to the cell

Horvitz, H. Robert

256

The Caenorhabditis elegans Werner Syndrome Protein Functions Upstream of ATR and ATM in Response to DNA  

E-print Network

The Caenorhabditis elegans Werner Syndrome Protein Functions Upstream of ATR and ATM in Response syndrome protein, a RecQ helicase, mutations of which are associated with premature aging and increased-S (2010) The Caenorhabditis elegans Werner Syndrome Protein Functions Upstream of ATR and ATM in Response

Gartner, Anton

257

Modeling the Establishment of PAR Protein Polarity in the One-Cell C. elegans Embryo  

E-print Network

Modeling the Establishment of PAR Protein Polarity in the One-Cell C. elegans Embryo Filipe ABSTRACT At the one-cell stage, the C. elegans embryo becomes polarized along the anterior-posterior axis by cytoskeletal rearrangement. Initially, the PAR proteins are uniformly distributed throughout the embryo. After

Howard, Martin

258

Sexual reproduction in solitary corals: Overlapping oogenic and brooding cycles, and benthic planulas in Balanophyllia elegans  

Microsoft Academic Search

The temperate solitary coral Balanophyllia elegans Verrill, 1864 was collected monthly between January 1977 and August 1978 off the California coast. B. elegans reproduces only sexually, is gonochoric, and broods its embryos. Males are ripe only in late summer, but oocytes and embryos (ca. 40 per female) are found throughout the year. The presence of oocytes and embryos throughout the

Y. H. Fadlallah; J. S. Pearse

1982-01-01

259

Successful reproduction of the introduced slider turtle(Trachemys scripta elegans) in the South of France  

Microsoft Academic Search

Massive importation of slider turtles (Trachemys scripta elegans) as a pet in France over the past few decades has been followed by the release of many of these turtles into natural environments. T. scripta elegans is now widely distributed in France. 2. This paper reports on the successful reproduction of this species in France, with confirmed production of both sexes

Antoine Cadi; Virginie Delmas; Anne-Caroline Prévot-Julliard; Pierre Joly; Claude Pieau; Marc Girondot

2004-01-01

260

Influence of Silicon on Resistance of Zinnia Elegans to Myzus Persicae (Hemiptera: Aphididae)  

Technology Transfer Automated Retrieval System (TEKTRAN)

Studies were conducted to examine the effect of treating Zinnia elegans Jacq. with soluble silicon on the performance of the green peach aphid, Myzus persicae (Sulzer). Zinnia elegans plants were irrigated every 2 days throughout the duration of the experiment with a nutrient solution amended with ...

261

Insight into transcription factor gene duplication from Caenorhabditis elegans Promoterome-driven expression patterns  

Microsoft Academic Search

BACKGROUND: The C. elegans Promoterome is a powerful resource for revealing the regulatory mechanisms by which transcription is controlled pan-genomically. Transcription factors will form the core of any systems biology model of genome control and therefore the promoter activity of Promoterome inserts for C. elegans transcription factor genes was examined, in vivo, with a reporter gene approach. RESULTS: Transgenic C.

John S Reece-Hoyes; Jane Shingles; Denis Dupuy; Christian A Grove; Albertha JM Walhout; Marc Vidal; Ian A Hope

2007-01-01

262

Caenorhabditis elegans Aurora A kinase AIR-1 Is Required for Postembryonic Cell Divisions and Germline  

E-print Network

LETTER Caenorhabditis elegans Aurora A kinase AIR-1 Is Required for Postembryonic Cell Divisions the eukaryotic cell cycle. The Aurora kinases comprise a highly conserved family of serine/threonine kinases a sterile Caenorhabditis elegans mutant in which the majority of the locus encoding the Aurora A kinase air

Baillie, David

263

A Chemosensory Adaptation Module for the Physiology Laboratory from Student-Directed "C. elegans" Research  

ERIC Educational Resources Information Center

The model organism, "Caenorhabditis elegans," in addition to being well suited to genetics and cell biology teaching applications, can also be useful in the physiology laboratory. In this article, the author describes how students in a junior level college Comparative Physiology course have made use of "C. elegans" in semester-long,…

Lindblom, Tim

2006-01-01

264

Nature Macmillan Publishers Ltd 1998 gate C. elegans genes. Comparison with pre-  

E-print Network

the course of the Human Genome Project, pushing it from a mapping mode to a sequencing mode. Second, the C. elegans project has been a model for how an efficient genome effort can be run. As far as I know rather than a researcher-orientated strategy. Third, the C. elegans Genome Project has stimulated

Koehl, Mimi

265

Distinct Pathogenesis and Host Responses during Infection of C. elegans by P. aeruginosa and S. aureus  

Microsoft Academic Search

The genetically tractable model host Caenorhabditis elegans provides a valuable tool to dissect host-microbe interactions in vivo. Pseudomonas aeruginosa and Staphylococcus aureus utilize virulence factors involved in human disease to infect and kill C. elegans. Despite much progress, virtually nothing is known regarding the cytopathology of infection and the proximate causes of nematode death. Using light and electron microscopy, we

Javier E. Irazoqui; Emily R. Troemel; Rhonda L. Feinbaum; Lyly G. Luhachack; Brent O. Cezairliyan; Frederick M. Ausubel

2010-01-01

266

Automated Quantification of Synaptic Fluorescence in C. elegans  

PubMed Central

Synapse strength refers to the amplitude of postsynaptic responses to presynaptic neurotransmitter release events, and has a major impact on overall neural circuit function. Synapse strength critically depends on the abundance of neurotransmitter receptors clustered at synaptic sites on the postsynaptic membrane. Receptor levels are established developmentally, and can be altered by receptor trafficking between surface-localized, subsynaptic, and intracellular pools, representing important mechanisms of synaptic plasticity and neuromodulation. Rigorous methods to quantify synaptically-localized neurotransmitter receptor abundance are essential to study synaptic development and plasticity. Fluorescence microscopy is an optimal approach because it preserves spatial information, distinguishing synaptic from non-synaptic pools, and discriminating among receptor populations localized to different types of synapses. The genetic model organism Caenorhabditis elegans is particularly well suited for these studies due to the small size and relative simplicity of its nervous system, its transparency, and the availability of powerful genetic techniques, allowing examination of native synapses in intact animals. Here we present a method for quantifying fluorescently-labeled synaptic neurotransmitter receptors in C. elegans. Its key feature is the automated identification and analysis of individual synapses in three dimensions in multi-plane confocal microscope output files, tabulating position, volume, fluorescence intensity, and total fluorescence for each synapse. This approach has two principal advantages over manual analysis of z-plane projections of confocal data. First, because every plane of the confocal data set is included, no data are lost through z-plane projection, typically based on pixel intensity averages or maxima. Second, identification of synapses is automated, but can be inspected by the experimenter as the data analysis proceeds, allowing fast and accurate extraction of data from large numbers of synapses. Hundreds to thousands of synapses per sample can easily be obtained, producing large data sets to maximize statistical power. Considerations for preparing C. elegans for analysis, and performing confocal imaging to minimize variability between animals within treatment groups are also discussed. Although developed to analyze C. elegans postsynaptic receptors, this method is generally useful for any type of synaptically-localized protein, or indeed, any fluorescence signal that is localized to discrete clusters, puncta, or organelles. The procedure is performed in three steps: 1) preparation of samples, 2) confocal imaging, and 3) image analysis. Steps 1 and 2 are specific to C. elegans, while step 3 is generally applicable to any punctate fluorescence signal in confocal micrographs. PMID:22907390

Sturt, Brianne L.; Bamber, Bruce A.

2012-01-01

267

Biological activity of Bacillus thuringiensis (Bacillales: Bacillaceae) chitinase against Caenorhabditis elegans (Rhabditida: Rhabditidae).  

PubMed

In addition to being used increasingly as a model system in modern molecular biology studies, the free-living nematode Caenorhabditis elegans (Maupas, 1900) is an important pathogen in fungi and straw mushrooms. In this study, Bacillus thuringiensis strain 010 was found to have significantly detrimental activity against C. elegans. To further characterize this activity, the toxicological mechanism was elucidated at molecular level. Genes encoding for crystal protein and chitinase were isolated, cloned, and sequenced. However, the toxicity was detected only in the chitinase. Under transmission electron microscopy, change in the body wall and gut structures of C. elegans was observed, and thus degeneration of body wall and gut in the worms was also investigated. Further bioassay also confirmed the mortality of C. elegans fed with Escherichia coli TB1 strain. These observations suggest great potential for B. thuringiensis 010 as a biocontrol agent against C. elegans and other nematodes. PMID:24772534

Zhang, Lingling; Yu, Jie; Xie, Yufei; Lin, Hongli; Huang, Zhipeng; Xu, Lei; Gelbic, Ivan; Guan, Xiong

2014-04-01

268

Engineering recombinant Orsay virus directly in the metazoan host Caenorhabditis elegans.  

PubMed

The recent identification of Orsay virus, the first virus that is capable of naturally infecting Caenorhabditis elegans, provides a unique opportunity to explore host-virus interaction studies in this invaluable model organism. A key feature of this system is the robust genetic tractability of the host, C. elegans, which would ideally be complemented by the ability to genetically manipulate Orsay virus in parallel. To this end, we developed a plasmid-based reverse genetics system for Orsay virus by creating transgenic C. elegans strains harboring Orsay virus cDNAs. Both wild-type and mutant Orsay viruses, including a FLAG epitope-tagged recombinant Orsay virus, were generated by use of the reverse genetics system. This is the first plasmid-based virus reverse genetics system in the metazoan C. elegans. The Orsay virus reverse genetics we established will serve as a fundamental tool in host-virus interaction studies in the model organism C. elegans. Importance: To date, Orsay virus is the first and the only identified virus capable of naturally infecting Caenorhabditis elegans. C. elegans is a simple multicellular model organism that mimics many fundamental features of human biology and has been used to define many biological properties conserved through evolution. Thus, the Orsay virus-C. elegans infection system provides a unique opportunity to study host-virus interactions. In order to take maximal advantage of this system, the ability to genetically engineer mutant forms of Orsay virus would be highly desirable. Most efforts to engineer viruses have been done with cultured cells. Here we describe the creation of mutant viruses directly in the multicellular organism C. elegans without the use of cell culture. We engineered a virus expressing a genetically tagged protein that could be detected in C. elegans. This provides proof of concept for modifying Orsay virus, which will greatly facilitate studies in this experimental system. PMID:25078701

Jiang, Hongbing; Franz, Carl J; Wang, David

2014-10-01

269

An unusual variant of Trichophyton tonsurans var. sulfureum.  

PubMed

A fungus, recovered from a skin lesion of a patient, produced velvety to powdery, white to deep yellow colonies on Sabouraud glucose agar. Microscopically, it produced a large number of cylindric, smooth-walled, three- to eight-celled macroconidia but failed to produce microconidia on a variety of nutritional media such as rice grains, cornmeal dextrose, potato dextrose, Sabouraud glucose, oatmeal and lactrimel agars. It hydrolysed urea in 7 days, perforated hair in vitro and required thiamine for growth. This isolate represents an atypical variant of Trichophyton tonsurans var. sufureum subvar. perforans. PMID:8064546

Padhye, A A; Weitzman, I; Domenech, E

1994-01-01

270

Sesquiterpenes and other constituents from Dendranthema zawadskii var. latilobum.  

PubMed

Six new germacranolides, zawadskinolides A-F (1-6), and a new eudesmane glucoside, chrysantiloboside (7) were isolated from the aerial parts of Dendranthema zawadskii var. latilobum, along with thirteen known constituents. Their structures were elucidated by means of spectroscopic evidence. Bioassay showed that flavonoids such as apigenin (9), (-)-eriodictyol (10) and nepetin (12), as well as the sesquiterpene lactone, zawadskinolide F (6), inhibited nitric oxide (NO) production in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophage cells with IC50 values of 66.15, 132.55, 35.44, and 91.32??M, respectively. PMID:22382409

Shin, Hyun Jung; Lee, So Young; Kim, Ju Sun; Lee, Sanghyun; Choi, Ran Joo; Chung, Ha Sook; Kim, Yeong Shik; Kang, Sam Sik

2012-01-01

271

A flavonol triglycoside from Actinidia arguta var. giraldii.  

PubMed

In the course of a chemotaxonomic study of the genus Actinidia a new flavonol triglycoside, quercetin 3-O-beta-D-[2G-O-beta-D-xylopyranosyl-6G-O-alpha-L-rhamnopyranosyl] glucopyranoside was identified amongst the 15 flavonols found in Actinidia arguta var. giraldii. This compound was characterized, along with quercetin 3-O-beta-D-xylopyranosyl-(1-2)-O-beta-D-glucopyranoside, by 1H and 13C NMR spectroscopy. The kaempferol analogues were also isolated. PMID:1367654

Webby, R F

1991-01-01

272

Novel diterpenes from the heartwood of Chamaecyparis obtusa var. formosana.  

PubMed

Two novel diterpenes, obtusanal B (1) and obtusadione (2), along with obtusanal A (3), obtunone (4), 12-hydroxy-6,7-secoabieta-8,11,13-triene-6,7-dial, 8,12-dihydroxydielmentha-5,9-diene-7,11-dione and myrcene, isolated from the heartwood of Chamaecyparis obtusa var. formosana, were characterized by spectroscopic means, including 2D-NMR techniques. Compounds 1 and 2 are 7(6-->2)abeoabietane and 14(8-->9)abeoabietane type diterpenes, respectively. Their biosyntheses were proposed. PMID:15187404

Kuo, Yueh-Hsiung; Chen, Chia-Hsien; Chien, Shih-Chang; Lin, Hsiu-Chuan

2004-06-01

273

[Chemical constituents of leaves of Panax japonicus var. major].  

PubMed

Seven compounds were isolated from the leaves of Panax japonicus var. major by chromatographic methods including silica gel, Sephadex LH-20, ODS and semi-preparative HPLC. Their structures were elucidated by their physical and chemical properties and spectral data analysis as 5, 7-dihydroxy-8-methoxyl flavone (1), ginsenoside Rs2 (2), quinquenoside R1 (3), ginsenoside Rs1 (4), notoginsenoside Fe (5), ginsenoside Rd2 (6) and gypenosiden IX (7). Among them, compound 1 was obtained from the Panax genus for the first time, and compounds 2-7 were isolated from this plant for the first time. PMID:25095375

He, Rui; Liu, Qi; Liu, Yin-Huan; Chai, Jiang; Zhao, Dong-Dong; Wang, Wei; Cui, Jiu-Cheng; Song, Xiao-Mei; Yue, Zheng-Gang

2014-05-01

274

Structural Properties of the Caenorhabditis elegans Neuronal Network  

PubMed Central

Despite recent interest in reconstructing neuronal networks, complete wiring diagrams on the level of individual synapses remain scarce and the insights into function they can provide remain unclear. Even for Caenorhabditis elegans, whose neuronal network is relatively small and stereotypical from animal to animal, published wiring diagrams are neither accurate nor complete and self-consistent. Using materials from White et al. and new electron micrographs we assemble whole, self-consistent gap junction and chemical synapse networks of hermaphrodite C. elegans. We propose a method to visualize the wiring diagram, which reflects network signal flow. We calculate statistical and topological properties of the network, such as degree distributions, synaptic multiplicities, and small-world properties, that help in understanding network signal propagation. We identify neurons that may play central roles in information processing, and network motifs that could serve as functional modules of the network. We explore propagation of neuronal activity in response to sensory or artificial stimulation using linear systems theory and find several activity patterns that could serve as substrates of previously described behaviors. Finally, we analyze the interaction between the gap junction and the chemical synapse networks. Since several statistical properties of the C. elegans network, such as multiplicity and motif distributions are similar to those found in mammalian neocortex, they likely point to general principles of neuronal networks. The wiring diagram reported here can help in understanding the mechanistic basis of behavior by generating predictions about future experiments involving genetic perturbations, laser ablations, or monitoring propagation of neuronal activity in response to stimulation. PMID:21304930

Varshney, Lav R.; Chen, Beth L.; Paniagua, Eric; Hall, David H.; Chklovskii, Dmitri B.

2011-01-01

275

Undulatory locomotion of finite filaments: lessons from Caenorhabditis elegans  

NASA Astrophysics Data System (ADS)

Undulatory swimming is a widespread propulsion strategy adopted by many small-scale organisms including various single-cell eukaryotes and nematodes. In this work, we report a comprehensive study of undulatory locomotion of a finite filament using (i) approximate resistive force theory (RFT) assuming a local nature of hydrodynamic interaction between the filament and the surrounding viscous liquid and (ii) particle-based numerical computations taking into account the intra-filament hydrodynamic interaction. Using the ubiquitous model of a propagating sinusoidal waveform, we identify the limit of applicability of the RFT and determine the optimal propulsion gait in terms of (i) swimming distance per period of undulation and (ii) hydrodynamic propulsion efficiency. The occurrence of the optimal swimming gait maximizing hydrodynamic efficiency at finite wavelength in particle-based computations diverges from the prediction of the RFT. To compare the model swimmer powered by sine wave undulations to biological undulatory swimmers, we apply the particle-based approach to study locomotion of the model organism nematode Caenorhabditis elegans using the swimming gait extracted from experiments. The analysis reveals that even though the amplitude and the wavenumber of undulations are similar to those determined for the best performing sinusoidal swimmer, C. elegans overperforms the latter in terms of both displacement and hydrodynamic efficiency. Further comparison with other undulatory microorganisms reveals that many adopt waveforms with characteristics similar to the optimal model swimmer, yet real swimmers still manage to beat the best performing sine-wave swimmer in terms of distance covered per period. Overall our results underline the importance of further waveform optimization, as periodic undulations adopted by C. elegans and other organisms deviate considerably from a simple sine wave.

Berman, R. S.; Kenneth, O.; Sznitman, J.; Leshansky, A. M.

2013-07-01

276

Characterisation of Caenorhabditis elegans sperm transcriptome and proteome  

PubMed Central

Background Although sperm is transcriptionally and translationally quiescent, complex populations of RNAs, including mRNAs and non-coding RNAs, exist in sperm. Previous microarray analysis of germ cell mutants identified hundreds of sperm genes in Caenorhabditis elegans. To take a more comprehensive view on C. elegans sperm genes, here, we isolate highly pure sperm cells and employ high-throughput technologies to obtain sperm transcriptome and proteome. Results First, sperm transcriptome consists of considerable amounts of non-coding RNAs, many of which have not been annotated and may play functional roles during spermatogenesis. Second, apart from kinases/phosphatases as previously reported, ion binding proteins are also enriched in sperm, underlying the crucial roles of intracellular ions in post-translational regulation in sperm. Third, while the majority of sperm genes/proteins have low abundance, a small number of sperm genes/proteins are hugely enriched in sperm, implying that sperm only rely on a small set of proteins for post-translational regulation. Lastly, by extensive RNAi screening of sperm enriched genes, we identified a few genes that control fertility. Our further analysis reveals a tight correlation between sperm transcriptome and sperm small RNAome, suggesting that the endogenous siRNAs strongly repress sperm genes. This leads to an idea that the inefficient RNAi screening of sperm genes, a phenomenon currently with unknown causes, might result from the competition between the endogenous RNAi pathway and the exogenous RNAi pathway. Conclusions Together, the obtained sperm transcriptome and proteome serve as valuable resources to systematically study spermatogenesis in C. elegans. PMID:24581041

2014-01-01

277

The transcription start site landscape of C. elegans  

PubMed Central

More than half of Caenorhabditis elegans pre-mRNAs lose their original 5? ends in a process termed “trans-splicing” in which the RNA extending from the transcription start site (TSS) to the site of trans-splicing of the primary transcript, termed the “outron,” is replaced with a 22-nt spliced leader. This complicates the mapping of TSSs, leading to a lack of available TSS mapping data for these genes. We used growth at low temperature and nuclear isolation to enrich for transcripts still containing outrons, applying a modified SAGE capture procedure and high-throughput sequencing to characterize 5? termini in this transcript population. We report from this data both a landscape of 5?-end utilization for C. elegans and a representative collection of TSSs for 7351 trans-spliced genes. TSS distributions for individual genes were often dispersed, with a greater average number of TSSs for trans-spliced genes, suggesting that trans-splicing may remove selective pressure for a single TSS. Upstream of newly defined TSSs, we observed well-known motifs (including TATAA-box and SP1) as well as novel motifs. Several of these motifs showed association with tissue-specific expression and/or conservation among six worm species. Comparing TSS features between trans-spliced and non-trans-spliced genes, we found stronger signals among outron TSSs for preferentially positioning of flanking nucleosomes and for downstream Pol II enrichment. Our data provide an enabling resource for both experimental and theoretical analysis of gene structure and function in C. elegans. PMID:23636945

Saito, Taro Leo; Hashimoto, Shin-ichi; Gu, Sam Guoping; Morton, J. Jason; Stadler, Michael; Blumenthal, Thomas; Fire, Andrew; Morishita, Shinichi

2013-01-01

278

Drug Absorption Efficiency in Caenorhbditis elegans Delivered by Different Methods  

PubMed Central

Background Caenorhbditis elegans has being vigorously used as a model organism in many research fields and often accompanied by administrating with various drugs. The methods of delivering drugs to worms are varied from one study to another, which make difficult in comparing results between studies. Methodology/Principal Findings We evaluated the drug absorption efficiency in C. elegans using five frequently used methods with resveratrol with low aqueous solubility and water-soluble 5-Fluoro-2?-deoxyuridine (FUDR) as positive compounds. The drugs were either applied to the LB medium with bacteria OP50, before spreading onto Nematode Growth Medium (NGM) plates (LB medium method), or to the NGM with live (NGM live method) or dead bacteria (NGM dead method), or spotting the drug solution to the surface of plates directly (spot dead method), or growing the worms in liquid medium (liquid growing method). The concentration of resveratrol and FUDR increased gradually within C. elegans and reached the highest during 12 hours to one day and then decreased slowly. At the same time point, the higher the drug concentration, the higher the metabolism rate. The drug concentrations in worms fed with dead bacteria were higher than with live bacteria at the same time point. Consistently, the drug concentration in medium with live bacteria decreased much faster than in medium with dead bacteria, reach to about half of the original concentration within 12 hours. Conclusion Resveratrol with low aqueous solubility and water-soluble FUDR have the same absorption and metabolism pattern. The drug metabolism rate in worms was both dosage and time dependent. NGM dead method and liquid growing method achieved the best absorption efficiency in worms. The drug concentration within worms was comparable with that in mice, providing a bridge for dose translation from worms to mammals. PMID:23451103

Zheng, Shan-Qing; Ding, Ai-Jun; Li, Guo-Ping; Wu, Gui-Sheng; Luo, Huai-Rong

2013-01-01

279

Caenorhabditis elegans-based Model Systems for Antifungal Drug Discovery  

PubMed Central

The substantial morbidity and mortality associated with invasive fungal infections constitute undisputed tokens of their severity. The continued expansion of susceptible population groups (such as immunocompromised individuals, patients undergoing extensive surgery, and those hospitalized with serious underlying diseases especially in the intensive care unit) and the limitations of current antifungal agents due to toxicity issues or to the development of resistance, mandate the development of novel antifungal drugs. Currently, drug discovery is transitioning from the traditional in vitro large-scale screens of chemical libraries to more complex bioassays, including in vivo studies on whole animals; invertebrates, such as Caenorhabditis elegans, are thus gaining momentum as screening tools. Key pathogenesis features of fungal infections, including filament formation, are expressed in certain invertebrate and mammalian hosts; among the various potential hosts, C. elegans provides an attractive platform both for the study of host-pathogen interactions and the identification of new antifungal agents. Advantages of compound screening in this facile, relatively inexpensive and not as ethically challenged whole-animal context, include the simultaneous assessment of antifungal efficacy and toxicity that could result in the identification of compounds with distinct mechanisms of action, for example by promoting host immune responses or by impeding fungal virulence factors. With the recent advent of using predictive models to screen for compounds with improved chances of bioavailability in the nematode a priori, high-throughput screening of chemical libraries using the C. elegans-c. albicans antifungal discovery assay holds even greater promise for the identification of novel antifungal agents in the near future. PMID:21470110

Anastassopoulou, Cleo G.; Fuchs, Beth Burgwyn; Mylonakis, Eleftherios

2013-01-01

280

Isolation of Specific Neurons from C. elegans Larvae for Gene Expression Profiling  

PubMed Central

Background The simple and well-described structure of the C. elegans nervous system offers an unprecedented opportunity to identify the genetic programs that define the connectivity and function of individual neurons and their circuits. A correspondingly precise gene expression map of C. elegans neurons would facilitate the application of genetic methods toward this goal. Here we describe a powerful new approach, SeqCeL (RNA-Seq of C. elegans cells) for producing gene expression profiles of specific larval C. elegans neurons. Methods and Results We have exploited available GFP reporter lines for FACS isolation of specific larval C. elegans neurons for RNA-Seq analysis. Our analysis showed that diverse classes of neurons are accessible to this approach. To demonstrate the applicability of this strategy to rare neuron types, we generated RNA-Seq profiles of the NSM serotonergic neurons that occur as a single bilateral pair of cells in the C. elegans pharynx. These data detected >1,000 NSM enriched transcripts, including the majority of previously known NSM-expressed genes. Significance This work offers a simple and robust protocol for expression profiling studies of post-embryonic C. elegans neurons and thus provides an important new method for identifying candidate genes for key roles in neuron-specific development and function. PMID:25372608

Spencer, W. Clay; McWhirter, Rebecca; Miller, Tyne; Strasbourger, Pnina; Thompson, Owen; Hillier, LaDeana W.; Waterston, Robert H.; Miller, David M.

2014-01-01

281

Caenorhabditis elegans - A model system for space biology studies  

NASA Technical Reports Server (NTRS)

The utility of the nematode Caenorhabditis elegans in studies spanning aspects of development, aging, and radiobiology is reviewed. These topics are interrelated via cellular and DNA repair processes especially in the context of oxidative stress and free-radical metabolism. The relevance of these research topics to problems in space biology is discussed and properties of the space environment are outlined. Exposure to the space-flight environment can induce rapid changes in living systems that are similar to changes occurring during aging; manipulation of these environmental parameters may represent an experimental strategy for studies of development and senescence. The current and future opportunities for such space-flight experimentation are presented.

Johnson, Thomas E.; Nelson, Gregory A.

1991-01-01

282

mRNA surveillance mitigates genetic dominance in Caenorhabditis elegans  

Microsoft Academic Search

Nonsense mutant mRNAs are unstable in all eucaryotes tested, a phenomenon termed nonsense-mediated mRNA decay (NMD) or mRNA\\u000a surveillance. Functions of the seven smg genes are required for mRNA surveillance in Caenorhabditis elegans. In Smg(+) genetic backgrounds, nonsense-mutant mRNAs are unstable, while in Smg(?) backgrounds such mRNAs are stable. Previous\\u000a work has demonstrated that the elevated level of nonsense-mutant mRNAs

B. M. Cali; P. Anderson

1998-01-01

283

Diurnal ventilatory patterns in the garter snake, Thamnophis elegans  

Microsoft Academic Search

Garter snakes,Thamnophis elegans, were entrained to a 14L (06.30–20.30 h) 10D (20.30–06.30 h) cycle for five weeks at 25 °C. Following entrainment, simultaneous measurements of ventilation and oxygen uptake were made. Pulmonary oxygen uptake (\\u000a$$\\\\dot V_{O_2 } $$\\u000a) exhibited a diurnal rhythm with minimum values of\\u000a$$\\\\dot V_{O_2 } $$\\u000a occurring during 10D. The diurnal rhythm persisted during

James W. Hicks; Marvin L. Riedesel

1983-01-01

284

Google matrix analysis of C.elegans neural network  

E-print Network

We study the structural properties of the neural network of the C.elegans (worm) from a directed graph point of view. The Google matrix analysis is used to characterize the neuron connectivity structure and node classifications are discussed and compared with physiological properties of the cells. Our results are obtained by a proper definition of neural directed network and subsequent eigenvector analysis which recovers some results of previous studies. Our analysis highlights particular sets of important neurons constituting the core of the neural system. The applications of PageRank, CheiRank and ImpactRank to characterization of interdependency of neurons are discussed.

Kandiah, Vivek

2013-01-01

285

Population dynamics and habitat sharing of natural populations of Caenorhabditis elegans and C. briggsae  

PubMed Central

Background The nematode Caenorhabditis elegans is a major model organism in laboratory biology. Very little is known, however, about its ecology, including where it proliferates. In the past, C. elegans was mainly isolated from human-made compost heaps, where it was overwhelmingly found in the non-feeding dauer diapause stage. Results C. elegans and C. briggsae were found in large, proliferating populations in rotting plant material (fruits and stems) in several locations in mainland France. Both species were found to co-occur in samples isolated from a given plant species. Population counts spanned a range from one to more than 10,000 Caenorhabditis individuals on a single fruit or stem. Some populations with an intermediate census size (10 to 1,000) contained no dauer larvae at all, whereas larger populations always included some larvae in the pre-dauer or dauer stages. We report on associated micro-organisms, including pathogens. We systematically sampled a spatio-temporally structured set of rotting apples in an apple orchard in Orsay over four years. C. elegans and C. briggsae were abundantly found every year, but their temporal distributions did not coincide. C. briggsae was found alone in summer, whereas both species co-occurred in early fall and C. elegans was found alone in late fall. Competition experiments in the laboratory at different temperatures show that C. briggsae out-competes C. elegans at high temperatures, whereas C. elegans out-competes C. briggsae at lower temperatures. Conclusions C. elegans and C. briggsae proliferate in the same rotting vegetal substrates. In contrast to previous surveys of populations in compost heaps, we found fully proliferating populations with no dauer larvae. The temporal sharing of the habitat by the two species coincides with their temperature preference in the laboratory, with C. briggsae populations growing faster than C. elegans at higher temperatures, and vice at lower temperatures. PMID:22731941

2012-01-01

286

Feeding Inhibition in Black Fly Larvae (Diptera: Simuliidae) and Its Effects on the Pathogenicity of Bacillus thuringiensis var. israelensis1  

E-print Network

on the Pathogenicity of Bacillus thuringiensis var. israelensis1 RANDY GAUGLER AND DANIEL MOLLOY Biological Survey, New. The pathogenicity of Bacillus thuringiensis var. israelensis against S. vittatum was di- minished or enhanced

287

A Field Test of Power Swing Damping by Static Var Compensator  

Microsoft Academic Search

This paper presents the results of a field test conducted for a static var compensator installed at a 500 kV substation. The static var compensator with a damping control function improved power system damping performance significantly by increasing the synchronizing and damping torques. Frequency response analysis was employed for examining the synchronizing and damping torques. Simulations of the test cases

T. Sawa; Y. Shirai; T. Michigami; Y. Sakanaka; Y. Uemura

1989-01-01

288

Spiral phyllotaxis of needle fascicles on branches and scales on cones in Pinus contorta var.  

E-print Network

Spiral phyllotaxis of needle fascicles on branches and scales on cones in Pinus contorta var-grain spiral in seedlings, young, and mature trees of Rocky Moun- tain lodgepole pine (Pinus contorta Dougl. ex, Pinus contorta var. latifolia, phyllotaxis, generative spiral, Fibonacci numbers, spiral wood grain

Coxson, Darwyn

289

Amlioration des plantes Obtention chez l'chalote (Allium cepa L var  

E-print Network

in shallot (Allium cepa L var aggregatum). Embryos of gynogenetic origin have been obtained by in vitro culture of flower buds from many shallot genotypes on basal B5 medium of Gamborg with high sucrose haploids in shallot breeding can now be proposed. Allium cepa L var aggregatum = shallot / gynogenesis

Paris-Sud XI, Université de

290

Generation of Antigenic Diversity in Plasmodium falciparum by Structured Rearrangement of Var Genes During Mitosis  

PubMed Central

The most polymorphic gene family in P. falciparum is the ?60 var genes distributed across parasite chromosomes, both in the subtelomeres and in internal regions. They encode hypervariable surface proteins known as P. falciparum erythrocyte membrane protein 1 (PfEMP1) that are critical for pathogenesis and immune evasion in Plasmodium falciparum. How var gene sequence diversity is generated is not currently completely understood. To address this, we constructed large clone trees and performed whole genome sequence analysis to study the generation of novel var gene sequences in asexually replicating parasites. While single nucleotide polymorphisms (SNPs) were scattered across the genome, structural variants (deletions, duplications, translocations) were focused in and around var genes, with considerable variation in frequency between strains. Analysis of more than 100 recombination events involving var exon 1 revealed that the average nucleotide sequence identity of two recombining exons was only 63% (range: 52.7–72.4%) yet the crossovers were error-free and occurred in such a way that the resulting sequence was in frame and domain architecture was preserved. Var exon 1, which encodes the immunologically exposed part of the protein, recombined in up to 0.2% of infected erythrocytes in vitro per life cycle. The high rate of var exon 1 recombination indicates that millions of new antigenic structures could potentially be generated each day in a single infected individual. We propose a model whereby var gene sequence polymorphism is mainly generated during the asexual part of the life cycle. PMID:25521112

Kekre, Mihir; Otto, Thomas D.; Faizullabhoy, Adnan; Rayner, Julian C.; Kwiatkowski, Dominic

2014-01-01

291

Molecular identification of the mycorrhizal fungi of the epiparasitic plant Monotropastrum humile var. glaberrimum (Ericaceae)  

Microsoft Academic Search

Achlorophyllous monotropoid plants (Monotropoideae, Ericaceae) are epiparasites that obtain all of their carbon from their host plants via connections with mycorrhizal fungi. The mycorrhizal fungi of the epiparasitic monotropoid Monotropastrum humile var. glaberrima were identified based on mitochondrial, large ribosomal DNA sequences, and were compared with those of another variety, M. humile var. humile. The fungi that inhabit M. humile

Jun Yokoyama; Tatsuya Fukuda; Hirokazu Tsukaya

2005-01-01

292

Power system planning and operations: Voltage-volt-ampere-reactive (VAR) projects: Seminar proceedings  

SciTech Connect

In recent years, utilities have placed new emphasis on improving their voltage - VAR planning, operation, and control practices. During this seminar, utility engineers had an opportunity to review five EPRI projects that have produced procedures and computer programs to assist in voltage - VAR management.

Not Available

1986-10-01

293

Evidence that the Human Pathogenic Fungus Cryptococcus neoformans var. grubii May Have Evolved in Africa  

Microsoft Academic Search

Most of the species of fungi that cause disease in mammals, including Cryptococcus neoformans var. grubii (serotype A), are exogenous and non-contagious. Cryptococcus neoformans var. grubii is associated worldwide with avian and arboreal habitats. This airborne, opportunistic pathogen is profoundly neurotropic and the leading cause of fungal meningitis. Patients with HIV\\/AIDS have been ravaged by cryptococcosis – an estimated one

Anastasia P. Litvintseva; Ignazio Carbone; Jenny Rossouw; Rameshwari Thakur; Nelesh P. Govender; Thomas G. Mitchell; Kirsten Nielsen

2011-01-01

294

Generation of Antigenic Diversity in Plasmodium falciparum by Structured Rearrangement of Var Genes During Mitosis.  

PubMed

The most polymorphic gene family in P. falciparum is the ?60 var genes distributed across parasite chromosomes, both in the subtelomeres and in internal regions. They encode hypervariable surface proteins known as P. falciparum erythrocyte membrane protein 1 (PfEMP1) that are critical for pathogenesis and immune evasion in Plasmodium falciparum. How var gene sequence diversity is generated is not currently completely understood. To address this, we constructed large clone trees and performed whole genome sequence analysis to study the generation of novel var gene sequences in asexually replicating parasites. While single nucleotide polymorphisms (SNPs) were scattered across the genome, structural variants (deletions, duplications, translocations) were focused in and around var genes, with considerable variation in frequency between strains. Analysis of more than 100 recombination events involving var exon 1 revealed that the average nucleotide sequence identity of two recombining exons was only 63% (range: 52.7-72.4%) yet the crossovers were error-free and occurred in such a way that the resulting sequence was in frame and domain architecture was preserved. Var exon 1, which encodes the immunologically exposed part of the protein, recombined in up to 0.2% of infected erythrocytes in vitro per life cycle. The high rate of var exon 1 recombination indicates that millions of new antigenic structures could potentially be generated each day in a single infected individual. We propose a model whereby var gene sequence polymorphism is mainly generated during the asexual part of the life cycle. PMID:25521112

Claessens, Antoine; Hamilton, William L; Kekre, Mihir; Otto, Thomas D; Faizullabhoy, Adnan; Rayner, Julian C; Kwiatkowski, Dominic

2014-12-01

295

miR-124/ATF-6, a novel lifespan extension pathway of Astragalus polysaccharide in Caenorhabditis elegans.  

PubMed

MicroRNAs (miRNAs), especially evolutionarily conserved miRNAs play critical roles in regulating various biological process. However, the functions of conserved miRNAs in longevity are still largely unknown. Astragalus polysaccharide (APS) was recently shown to extend lifespan of Caenorhabditis elegans, but its molecular mechanisms have not been fully understood. In the present study, we characterize that microRNA mediated a novel longevity pathway of APS in C. elegans. We found that APS markedly extended the lifespan of C. elegans at the second and the fourth stages. A highly conserved miRNA miR-124 was significantly upregulated in APS-treated C. elegans. Overexpression miR-124 caused the lifespan extension of C. elegans and vice versa, indicating miR-124 regulates the longevity of C. elegans. Using luciferase assay, atf-6 was established as a target gene of miR-124 which acting on three binding sites at atf-6 3'UTR. Consistently, agomir-cel-miR-124 was also shown to inhibit ATF-6 expression in C. elegans. APS-treated C. elegans showed the down-regulation of atf-6 at protein level. Furthermore, the knockdown of atf-6 by RNAi extended the lifespan of C. elegans, indicating atf-6 regulated by miR-124 contributes to lifespan extension. Taken together, miR-124 regulating ATF-6 is a new potential longevity signal pathway, which underlies the lifespan-extending effects of APS in C. elegans. PMID:25186652

Wang, Ning; Liu, Jing; Xie, Fang; Gao, Xu; Ye, Jian-Han; Sun, Lu-Yao; Wei, Ran; Ai, Jing

2015-02-01

296

Molecular structures of fructans from Agave tequilana Weber var. azul.  

PubMed

Agave plants utilize crassulacean acid metabolism (CAM) for CO(2) fixation. Fructans are the principal photosynthetic products generated by agave plants. These carbohydrates are fructose-bound polymers frequently with a single glucose moiety. Agave tequilana Weber var. azul is an economically important CAM species not only because it is the sole plant allowed for tequila production but because it is a potential source of prebiotics. Because of the large amounts of carbohydrates in A. tequilana, in this study the molecular structures of its fructans were determined by fructan derivatization for linkage analysis coupled with gas chromatography-mass spectrometry (GC-MS), nuclear magnetic resonance (NMR), and matrix-assisted laser desorption time-of-flight mass spectrometry (MALDI-TOF-MS). Fructans were extracted from 8-year-old A. tequilana plants. The linkage types present in fructans from A. tequilana were determined by permethylation followed by reductive cleavage, acetylation, and finally GC-MS analysis. Analysis of the degree of polymerization (DP) estimated by (1)H NMR integration and (13)C NMR and confirmed by MALDI-TOF-MS showed a wide DP ranging from 3 to 29 units. All of the analyses performed demonstrated that fructans from A. tequilana consist of a complex mixture of fructooligosaccharides containing principally beta(2 --> 1) linkages, but also beta(2 --> 6) and branch moieties were observed. Finally, it can be stated that fructans from A. tequilana Weber var. azul are not an inulin type as previously thought. PMID:14690361

Lopez, Mercedes G; Mancilla-Margalli, Norma A; Mendoza-Diaz, Guillermo

2003-12-31

297

1-MCP is more effective on a floral brassica ( Brassica oleracea var. italica L.) than a leafy brassica ( Brassica rapa var. chinensis)  

Microsoft Academic Search

Florets of broccoli (Brassica oleracea var. italica L.) and the youngest fully expanded leaf detached from pak choy (Brassica rapa var. chinensis) were treated with 1-methylcyclopropene (1-MCP) overnight (16 h) and then stored at supermarket retail temperature (10°C). A concentration of 12 ?l l?1 was considered optimal for both pak choy leaves and broccoli florets. 1-MCP increased shelf life of

Amanda J Able; Lung Sing Wong; Amikha Prasad; Timothy J O'Hare

2002-01-01

298

Empirical analysis on future-cash arbitrage risk with portfolio VaR  

NASA Astrophysics Data System (ADS)

This paper constructs the positive arbitrage position by alternating the spot index with Chinese Exchange Traded Fund (ETF) portfolio and estimating the arbitrage-free interval of futures with the latest trade data. Then, an improved Delta-normal method was used, which replaces the simple linear correlation coefficient with tail dependence correlation coefficient, to measure VaR (Value-at-risk) of the arbitrage position. Analysis of VaR implies that the risk of future-cash arbitrage is less than that of investing completely in either futures or spot market. Then according to the compositional VaR and the marginal VaR, we should increase the futures position and decrease the spot position appropriately to minimize the VaR, which can minimize risk subject to certain revenues.

Chen, Rongda; Li, Cong; Wang, Weijin; Wang, Ze

2014-03-01

299

Gait Modulation in C. elegans: An Integrated Neuromechanical Model  

PubMed Central

Equipped with its 302-cell nervous system, the nematode Caenorhabditis elegans adapts its locomotion in different environments, exhibiting so-called swimming in liquids and crawling on dense gels. Recent experiments have demonstrated that the worm displays the full range of intermediate behaviors when placed in intermediate environments. The continuous nature of this transition strongly suggests that these behaviors all stem from modulation of a single underlying mechanism. We present a model of C. elegans forward locomotion that includes a neuromuscular control system that relies on a sensory feedback mechanism to generate undulations and is integrated with a physical model of the body and environment. We find that the model reproduces the entire swim-crawl transition, as well as locomotion in complex and heterogeneous environments. This is achieved with no modulatory mechanism, except via the proprioceptive response to the physical environment. Manipulations of the model are used to dissect the proposed pattern generation mechanism and its modulation. The model suggests a possible role for GABAergic D-class neurons in forward locomotion and makes a number of experimental predictions, in particular with respect to non-linearities in the model and to symmetry breaking between the neuromuscular systems on the ventral and dorsal sides of the body. PMID:22408616

Boyle, Jordan H.; Berri, Stefano; Cohen, Netta

2012-01-01

300

The ubiquitin proteasome system in Caenorhabditis elegans and its regulation?  

PubMed Central

Protein degradation constitutes a major cellular function that is responsible for maintenance of the normal cellular physiology either through the degradation of normal proteins or through the elimination of damaged proteins. The Ubiquitin–Proteasome System (UPS)1 is one of the main proteolytic systems that orchestrate protein degradation. Given that up- and down- regulation of the UPS system has been shown to occur in various normal (such as ageing) and pathological (such as neurodegenerative diseases) processes, the exogenous modulation of the UPS function and activity holds promise of (a) developing new therapeutic interventions against various diseases and (b) establishing strategies to maintain cellular homeostasis. Since the proteasome genes are evolutionarily conserved, their role can be dissected in simple model organisms, such as the nematode, Caenorhabditis elegans. In this review, we survey findings on the redox regulation of the UPS in C. elegans showing that the nematode is an instrumental tool in the identification of major players in the UPS pathway. Moreover, we specifically discuss UPS-related genes that have been modulated in the nematode and in human cells and have resulted in similar effects thus further exhibiting the value of this model in the study of the UPS. PMID:24563851

Papaevgeniou, Nikoletta; Chondrogianni, Niki

2014-01-01

301

Analysis of intraflagellar transport in C. elegans sensory cilia.  

PubMed

Cilia are assembled and maintained by intraflagellar transport (IFT), the motor-dependent, bidirectional movement of multiprotein complexes, called IFT particles, along the axoneme. The sensory cilia of Caenorhabditis elegans represent very useful objects for studying IFT because of the availability of in vivo time-lapse fluorescence microscopy assays of IFT and multiple ciliary mutants. In this system there are 60 sensory neurons, each having sensory cilia on the endings of their dendrites, and most components of the IFT machinery operating in these structures have been identified using forward and reverse genetic approaches. By analyzing the rate of IFT along cilia within living wild-type and mutant animals, two anterograde and one retrograde IFT motors were identified, the functional coordination of the two anterograde kinesin-2 motors was established and the transport properties of all the known IFT particle components have been characterized. The anterograde kinesin motors have been heterologously expressed and purified, and their biochemical properties have been characterized using MT gliding and single molecule motility assays. In this chapter, we summarize how the tools of genetics, cell biology, electron microscopy, and biochemistry are being used to dissect the composition and mechanism of action of IFT motors and IFT particles in C. elegans. PMID:20409821

Hao, Limin; Acar, Seyda; Evans, James; Ou, Guangshuo; Scholey, Jonathan M

2009-01-01

302

Acute Drug Treatment in the Early C. elegans Embryo  

PubMed Central

Genetic and genome-wide RNAi approaches available in C. elegans, combined with tools for visualizing subcellular events with high-resolution, have led to increasing adoption of the early C. elegans embryo as a model for mechanistic and functional genomic analysis of cellular processes. However, a limitation of this system has been the impermeability of the embryo eggshell, which has prevented the routine use of small molecule inhibitors. Here, we present a method to permeabilize and immobilize embryos for acute inhibitor treatment in conjunction with live imaging. To identify a means to permeabilize the eggshell, we used a dye uptake assay to screen a set of 310 candidate genes defined by a combination of bioinformatic criteria. This screen identified 20 genes whose inhibition resulted in >75% eggshell permeability, and 3 that permeabilized embryos with minimal deleterious effects on embryo production and early embryonic development. To mount permeabilized embryos for acute drug addition in conjunction with live imaging, we combined optimized inhibition of one of these genes with the use of a microfabricated chamber that we designed. We demonstrate that these two developments enable the temporally controlled introduction of inhibitors for mechanistic studies. This method should also open new avenues of investigation by allowing profiling and specificity-testing of inhibitors through comparison with genome-wide phenotypic datasets. PMID:21935434

Zhang, Kelly; Noble, Lisa B.; Zanin, Esther; Desai, Arshad; Groisman, Alex; Oegema, Karen

2011-01-01

303

Changes in Caenorhabditis elegans exposed to Vibrio parahaemolyticus.  

PubMed

Vibrio parahaemolyticus, which owes its origin to the marine environment, is considered as one of the most common causes of infectious diarrhea worldwide. The present study investigated the pathogenicity of V. parahaemolyticus against the model organism, Caenorhabditis elegans. Infection in the host was localized with GFP-tagged V. parahaemolyticus using confocal laser scanning microscopy. The times required for causing infection, bacterial load in intestine, chemotactic response, and alteration in pharyngeal pumping were analyzed in the host system. In addition, the regulation of innate immune-related genes, lys-7, clec- 60, and clec-87, was analyzed using real-time PCR. The role of immune-responsible pmk-1 was studied using mutant strains. The pathogenicity of environmental strain CM2 isolated from the Gulf of Mannar, India was compared with that of a reference strain obtained from ATCC. The pathogen infected animals appeared to ward off infection by upregulating candidate antimicrobial genes for a few hours after the exposure, before succumbing to the pathogen. For the first time, the pathogenicity of V. parahaemolyticus at both the physiological and molecular levels has been studied in detail using the model organism C. elegans. PMID:22031026

Durai, Sellegounder; Karutha Pandian, Shunmugiah; Balamurugan, Krishnaswamy

2011-10-01

304

Hierarchical sparse coding in the sensory system of Caenorhabditis elegans  

PubMed Central

Animals with compact sensory systems face an encoding problem where a small number of sensory neurons are required to encode information about its surrounding complex environment. Using Caenorhabditis elegans worms as a model, we ask how chemical stimuli are encoded by a small and highly connected sensory system. We first generated a comprehensive library of transgenic worms where each animal expresses a genetically encoded calcium indicator in individual sensory neurons. This library includes the vast majority of the sensory system in C. elegans. Imaging from individual sensory neurons while subjecting the worms to various stimuli allowed us to compile a comprehensive functional map of the sensory system at single neuron resolution. The functional map reveals that despite the dense wiring, chemosensory neurons represent the environment using sparse codes. Moreover, although anatomically closely connected, chemo- and mechano-sensory neurons are functionally segregated. In addition, the code is hierarchical, where few neurons participate in encoding multiple cues, whereas other sensory neurons are stimulus specific. This encoding strategy may have evolved to mitigate the constraints of a compact sensory system. PMID:25583501

Zaslaver, Alon; Liani, Idan; Shtangel, Oshrat; Ginzburg, Shira; Yee, Lisa; Sternberg, Paul W.

2015-01-01

305

Manganese disturbs metal and protein homeostasis in Caenorhabditis elegans.  

PubMed

Parkinson's disease (PD) is a debilitating motor and cognitive neurodegenerative disorder for which there is no cure. While aging is the major risk factor for developing PD, clear environmental risks have also been identified. Environmental exposure to the manganese (Mn) metal is a prominent risk factor for developing PD and occupational exposure to high levels of Mn can cause a syndrome known as manganism, which has symptoms that closely resemble PD. In this study, we developed a model of manganism in the environmentally tractable nematode, Caenorhabditis elegans. We find that, in addition to previously described modes of Mn toxicity, which primarily include mitochondrial dysfunction and oxidative stress, Mn exposure also significantly antagonizes protein homeostasis, another key pathological feature associated with PD and many age-related neurodegenerative diseases. Mn treatment activates the ER unfolded protein response, severely exacerbates toxicity in a disease model of protein misfolding, and alters aggregate solubility. Further, aged animals, which have previously been shown to exhibit decreased protein homeostasis, are particularly susceptible to Mn toxicity when compared to young animals, indicating that the aging process sensitizes animals to metal toxicity. Mn exposure also significantly alters iron (Fe) and calcium (Ca) homeostasis, which is important for mitochondrial and ER health and which may further compound toxicity. These findings indicate that modeling manganism in C. elegans can provide a useful platform for identifying therapeutic interventions for ER stress, proteotoxicity, and age-dependent susceptibilities, key pathological features of PD and other related neurodegenerative diseases. PMID:25057947

Angeli, Suzanne; Barhydt, Tracy; Jacobs, Ross; Killilea, David W; Lithgow, Gordon J; Andersen, Julie K

2014-10-01

306

Phylogenetic analysis of cryptic speciation in the polychaete Pygospio elegans  

PubMed Central

Development in marine invertebrate species can take place through a variety of modes and larval forms, but within a species, developmental mode is typically uniform. Poecilogony refers to the presence of more than one mode of development within a single species. True poecilogony is rare, however, and in some cases, apparent poecilogony is actually the result of variation in development mode among recently diverged cryptic species. We used a phylogenetic approach to examine whether poecilogony in the marine polychaete worm, Pygospio elegans, is the result of cryptic speciation. Populations of worms identified as P. elegansooded, and intermediate larvae; these modes are found both within and among populations. We examined sequence variation among partial mitochondrial cytochrome c oxidase subunit I sequences obtained for 279 individual worms sampled across broad geographic and environmental scales. Despite a large number of unique haplotypes (121 haplotypes from 279 individuals), sequence divergence among European samples was low (1.7%) with most of the sequence variation observed within populations, relative to the variation among regions. More importantly, we observed common haplotypes that were widespread among the populations we sampled, and the two most common haplotypes were shared between populations differing in developmental mode. Thus, our results support an earlier conclusion of poecilogony in P elegans. In addition, predominantly planktonic populations had a larger number of population-specific low-frequency haplotypes. This finding is largely consistent with interspecies comparisons showing high diversity for species with planktonic developmental modes in contrast to low diversity in species with brooded developmental modes. PMID:22837844

Kesäniemi, J E; Rawson, P D; Lindsay, S M; Knott, K E

2012-01-01

307

Phenazine derivatives cause proteotoxicity and stress in C. elegans.  

PubMed

It is widely recognized that bacterial metabolites have toxic effects in animal systems. Phenazines are a common bacterial metabolite within the redox-active exotoxin class. These compounds have been shown to be toxic to the soil invertebrate Caenorhabditis elegans with the capability of causing oxidative stress and lethality. Here we report that chronic, low-level exposure to three separate phenazine molecules (phenazine-1-carboxylic acid, pyocyanin and 1-hydroxyphenazine) upregulated ER stress response and enhanced expression of a superoxide dismutase reporter in vivo. Exposure to these molecules also increased protein misfolding of polyglutamine and ?-synuclein in the bodywall muscle cells of C. elegans. Exposure of worms to these phenazines caused additional sensitivity in dopamine neurons expressing wild-type ?-synuclein, indicating a possible defect in protein homeostasis. The addition of an anti-oxidant failed to rescue the neurotoxic and protein aggregation phenotypes caused by these compounds. Thus, increased production of superoxide radicals that occurs in whole animals in response to these phenazines appears independent from the toxicity phenotype observed. Collectively, these data provide cause for further consideration of the neurodegenerative impact of phenazines. PMID:25304539

Ray, Arpita; Rentas, Courtney; Caldwell, Guy A; Caldwell, Kim A

2015-01-01

308

Fluorodeoxyuridine Improves Caenorhabditis elegans Proteostasis Independent of Reproduction Onset  

PubMed Central

Protein homeostasis (proteostasis) networks are dynamic throughout the lifespan of an organism. During Caenorhabditis elegans adulthood, the maintenance of metastable proteins and the activation of stress responses are inversely associated with germline stem cell proliferation. Here, we employed the thymidylate synthase inhibitor 5-fluoro-2?-deoxyuridine (FUdR) to chemically inhibit reproduction, thus allowing for examination of the interplay between reproduction and somatic proteostasis. We found that treatment with FUdR modulates proteostasis decline both before and after reproduction onset, such that effective induction of the heat shock response was maintained during adulthood and that metastable temperature-sensitive mutant phenotypes were rescued under restrictive conditions. However, FUdR treatment also improved the folding capacity of germline- and gonadogenesis-defective mutants, suggesting that proteostasis modulation by FUdR is independent of germline stem cell proliferation or inhibition of reproduction. Our data, therefore, indicate that FUdR converges on alternative regulatory signals that modulate C. elegans proteostasis capacity during development and adulthood. PMID:24465816

Ben-Zvi, Anat

2014-01-01

309

Propulsion of C. elegans crawling on a wet surface  

NASA Astrophysics Data System (ADS)

Nematodes, such as soil-dwelling worms C. elegans, propel themselves by producing undulatory body motion. An important requirement for effective propulsion is to have large transverse and small longitudinal friction forces acting on a crawling worm. Recently, Sauvage et al. have shown that soft-lubrication forces between the worm body and a moist supporting substrate can produce, at most, the transverse friction coefficient twice as large as the longitudinal friction coefficient (and this ratio is too small for efficient propulsion). Here we show that hydrodynamic resistance of the fluid in liquid film adjacent to the worm body can generate significantly larger transverse friction, which moreover, is wavelength dependent. By modeling the worm as a long chain of spheres in Hele--Shaw flow, we have determined the optimal wavelength and amplitude of the undulatory motion that optimizes propulsion efficiency for a given rate of energy dissipation. The optimal worm shape qualitatively agrees with our experimental observations of C. elegans crawling in moist environments.

Bilbao, A.; Alavalapadu, A.; Khan, Z. S.; Salomon, D. E.; Vanapalli, S. A.; Rumbaugh, K.; Blawzdziewicz, J.

2011-11-01

310

Molecular basis of the copulatory plug polymorphism in C. elegans  

PubMed Central

Heritable variation is the raw material for evolutionary change, and understanding its genetic basis is one of the central problems in modern biology. We investigated the genetic basis of a classic phenotypic dimorphism in the nematode Caenorhabditis elegans. Males from many natural isolates deposit a copulatory plug after mating, whereas males from other natural isolates—including the standard wild-type strain (N2 Bristol) that is used in most research laboratories—do not deposit plugs1. The copulatory plug is a gelatinous mass that covers the hermaphrodite vulva, and its deposition decreases the mating success of subsequent males2. We show that the plugging polymorphism results from the insertion of a retrotransposon into an exon of a novel mucin-like gene, plg-1, whose product is a major structural component of the copulatory plug. The gene is expressed in a subset of secretory cells of the male somatic gonad, and its loss has no evident effects beyond the loss of male mate-guarding. Although C. elegans descends from an obligate-outcrossing, male-female ancestor3, 4, it occurs primarily as self-fertilizing hermaphrodites5–7. The reduced selection on male-male competition associated with the origin of hermaphroditism may have permitted the global spread of a loss-of-function mutation with restricted pleiotropy. PMID:18633349

Palopoli, Michael F.; Rockman, Matthew V.; TinMaung, Aye; Ramsay, Camden; Curwen, Stephen; Aduna, Andrea; Laurita, Jason; Kruglyak, Leonid

2008-01-01

311

Imprinting capacity of gamete lineages in Caenorhabditis elegans.  

PubMed

We have observed a gamete-of-origin imprinting effect in C. elegans using a set of GFP reporter transgenes. From a single progenitor line carrying an extrachromosomal unc-54::gfp transgene array, we generated three independent autosomal integrations of the unc-54::gfp transgene. The progenitor line, two of its three integrated derivatives, and a nonrelated unc-119:gfp transgene exhibit an imprinting effect: single-generation transmission of these transgenes through the male germline results in approximately 1.5- to 2.0-fold greater expression than transmission through the female germline. There is a detectable resetting of the imprint after passage through the opposite germline for a single generation, indicating that the imprinted status of the transgenes is reversible. In cases where the transgene is maintained in either the oocyte lineage or sperm lineage for multiple, consecutive generations, a full reset requires passage through the opposite germline for several generations. Taken together, our results indicate that C. elegans has the ability to imprint chromosomes and that differences in the cell and/or molecular biology of oogenesis and spermatogenesis are manifest in an imprint that can persist in both somatic and germline gene expression for multiple generations. PMID:15944356

Sha, Ky; Fire, Andrew

2005-08-01

312

Neural integrity is maintained by dystrophin in C. elegans  

PubMed Central

The dystrophin protein complex (DPC), composed of dystrophin and associated proteins, is essential for maintaining muscle membrane integrity. The link between mutations in dystrophin and the devastating muscle failure of Duchenne’s muscular dystrophy (DMD) has been well established. Less well appreciated are the accompanying cognitive impairment and neuropsychiatric disorders also presented in many DMD patients, which suggest a wider role for dystrophin in membrane–cytoskeleton function. This study provides genetic evidence of a novel role for DYS-1/dystrophin in maintaining neural organization in Caenorhabditis elegans. This neuronal function is distinct from the established role of DYS-1/dystrophin in maintaining muscle integrity and regulating locomotion. SAX-7, an L1 cell adhesion molecule (CAM) homologue, and STN-2/?-syntrophin also function to maintain neural integrity in C. elegans. This study provides biochemical data that show that SAX-7 associates with DYS-1 in an STN-2/?-syntrophin–dependent manner. These results reveal a recruitment of L1CAMs to the DPC to ensure neural integrity is maintained. PMID:21242290

Zhou, Shan

2011-01-01

313

Genistein from Vigna angularis Extends Lifespan in Caenorhabditis elegans  

PubMed Central

The seed of Vigna angularis has long been cultivated as a food or a folk medicine in East Asia. Genistein (4?,5,7-trihydroxyisoflavone), a dietary phytoestrogen present in this plant, has been known to possess various biological properties. In this study, we investigated the possible lifespan-extending effects of genistein using Caenorhabditis elegans model system. We found that the lifespan of nematode was significantly prolonged in the presence of genistein under normal culture condition. In addition, genistein elevated the survival rate of nematode against stressful environment including heat and oxidative conditions. Further studies demonstrated that genistein-mediated increased stress tolerance of nematode could be attributed to enhanced expressions of stress resistance proteins such as superoxide dismutase (SOD-3) and heat shock protein (HSP-16.2). Moreover, we failed to find genistein-induced significant change in aging-related factors including reproduction, food intake, and growth, indicating genistein exerts longevity activity independent of affecting these factors. Genistein treatment also led to an up-regulation of locomotory ability of aged nematode, suggesting genistein affects healthspan as well as lifespan of nematode. Our results represent that genistein has beneficial effects on the lifespan of C. elegans under both of normal and stress condition via elevating expressions of stress resistance proteins.

Lee, Eun Byeol; Ahn, Dalrae; Kim, Ban Ji; Lee, So Yeon; Seo, Hyun Won; Cha, Youn-Soo; Jeon, Hoon; Eun, Jae Soon; Cha, Dong Seok; Kim, Dae Keun

2015-01-01

314

Genistein from Vigna angularis Extends Lifespan in Caenorhabditis elegans.  

PubMed

The seed of Vigna angularis has long been cultivated as a food or a folk medicine in East Asia. Genistein (4',5,7-trihydroxyisoflavone), a dietary phytoestrogen present in this plant, has been known to possess various biological properties. In this study, we investigated the possible lifespan-extending effects of genistein using Caenorhabditis elegans model system. We found that the lifespan of nematode was significantly prolonged in the presence of genistein under normal culture condition. In addition, genistein elevated the survival rate of nematode against stressful environment including heat and oxidative conditions. Further studies demonstrated that genistein-mediated increased stress tolerance of nematode could be attributed to enhanced expressions of stress resistance proteins such as superoxide dismutase (SOD-3) and heat shock protein (HSP-16.2). Moreover, we failed to find genistein-induced significant change in aging-related factors including reproduction, food intake, and growth, indicating genistein exerts longevity activity independent of affecting these factors. Genistein treatment also led to an up-regulation of locomotory ability of aged nematode, suggesting genistein affects healthspan as well as lifespan of nematode. Our results represent that genistein has beneficial effects on the lifespan of C. elegans under both of normal and stress condition via elevating expressions of stress resistance proteins. PMID:25593647

Lee, Eun Byeol; Ahn, Dalrae; Kim, Ban Ji; Lee, So Yeon; Seo, Hyun Won; Cha, Youn-Soo; Jeon, Hoon; Eun, Jae Soon; Cha, Dong Seok; Kim, Dae Keun

2015-01-01

315

Alteration in cellular acetylcholine influences dauer formation in Caenorhabditis elegans  

PubMed Central

Altered acetylcholine (Ach) homeostasis is associated with loss of viability in flies, developmental defects in mice, and cognitive deficits in human. Here, we assessed the importance of Ach in Caenorhabditis elegans development, focusing on the role of Ach during dauer formation. We found that dauer formation was disturbed in choline acetyltransferase (cha-1) and acetylcholinesterase (ace) mutants defective in Ach biosynthesis and degradation, respectively. When examined the potential role of G-proteins in dauer formation, goa-1 and egl-30 mutant worms, expressing mutated versions of mammalian Go and Gq homolog, respectively, showed some abnormalities in dauer formation. Using quantitative mass spectrometry, we also found that dauer larvae had lower Ach content than did reproductively grown larvae. In addition, a proteomic analysis of acetylcholinesterase mutant worms, which have excessive levels of Ach, showed differential expression of metabolic genes. Collectively, these results indicate that alterations in Ach release may influence dauer formation in C. elegans. [BMB Reports 2014; 47(2): 80-85] PMID:24219868

Lee, Jeeyong; Kim, Kwang-Youl; Paik, Young-Ki

2014-01-01

316

C. elegans metallothioneins: response to and defence against ROS toxicity.  

PubMed

The genome of the nematode Caenorhabditis elegans encodes for two multifunctional metal binding metallothioneins (MTs), CeMT-1 and CeMT-2. Here we applied qPCR to identify a transcriptional up-regulation following the exposure to free radical generators (ROS) paraquat or hydrogen peroxide, a trend that was confirmed with Pmtl::GFP expressing alleles. The deletion of the MT loci resulted in an elevation of in vivo levels of hydrogen peroxide and exposure to ROS caused a reduction in total egg production, growth and life span in wild type nematodes, effects that were particularly pronounced in the CeMT-2 and double knockout. Moreover, in vitro incubation of recombinant MTs with hydrogen peroxide demonstrated the presence of direct oxidation of the CeMTs, with zinc released from both isoforms and concomitant formation of intra-molecular disulfides. Finally, metabolic profiling (metabolomic) analysis of wild type and MT knockouts in the presence/absence of oxidative stressors, confirmed the overall trend described by the other experiments, and identified 2-aminoadipate as a potential novel small-molecule marker of oxidative stress. In summary, this study highlights that C. elegans metallothioneins scavenge and protect against reactive oxygen species and potentially against oxidative stress, with CeMT-2 being more effective than CeMT-1. PMID:21647514

Zeitoun-Ghandour, Sukaina; Leszczyszyn, Oksana I; Blindauer, Claudia A; Geier, Florian M; Bundy, Jacob G; Stürzenbaum, Stephen R

2011-08-01

317

Ecotoxicological assessment of lanthanum with Caenorhabditis elegans in liquid medium.  

PubMed

With their widespread applications in industry, agriculture and many other fields, more and more rare earth elements (REEs) are getting into the environment, especially the aquatic systems. Therefore, understanding the aquatic ecotoxicity of REEs has become more and more important. In the present work, Caenorhabditis elegans (C. elegans) was used as a test organism and life-cycle endpoints were chosen along with elemental assay to evaluate the aquatic toxicity of lanthanum (La), a representative of REEs. The results show La³+ had significant adverse effects on the growth and reproduction of worms above a concentration of 10 ?mol L?¹. The elemental mapping by microbeam synchrotron radiation X-ray fluorescence (?-SRXRF) illustrated how La treatment disturbed the metals distribution in the whole body of a single tiny nematode at lower levels. Our results suggested that the high-level REEs in some polluted water bodies would lead to an aquatic ecological crisis. The assessment we performed in the present work could be developed as a standardized test design for aquatic toxicological research. PMID:21510015

Zhang, Haifeng; He, Xiao; Bai, Wei; Guo, Xiaomei; Zhang, Zhiyong; Chai, Zhifang; Zhao, Yuliang

2010-12-01

318

Hierarchical sparse coding in the sensory system of Caenorhabditis elegans.  

PubMed

Animals with compact sensory systems face an encoding problem where a small number of sensory neurons are required to encode information about its surrounding complex environment. Using Caenorhabditis elegans worms as a model, we ask how chemical stimuli are encoded by a small and highly connected sensory system. We first generated a comprehensive library of transgenic worms where each animal expresses a genetically encoded calcium indicator in individual sensory neurons. This library includes the vast majority of the sensory system in C. elegans. Imaging from individual sensory neurons while subjecting the worms to various stimuli allowed us to compile a comprehensive functional map of the sensory system at single neuron resolution. The functional map reveals that despite the dense wiring, chemosensory neurons represent the environment using sparse codes. Moreover, although anatomically closely connected, chemo- and mechano-sensory neurons are functionally segregated. In addition, the code is hierarchical, where few neurons participate in encoding multiple cues, whereas other sensory neurons are stimulus specific. This encoding strategy may have evolved to mitigate the constraints of a compact sensory system. PMID:25583501

Zaslaver, Alon; Liani, Idan; Shtangel, Oshrat; Ginzburg, Shira; Yee, Lisa; Sternberg, Paul W

2015-01-27

319

Phytologia (August 2013) 95(3) 215 Juniperus communis var. kelleyi, a new variety from North America  

E-print Network

shown that taxa referred to as J. c. var. saxatilis in the eastern hemisphere and in North America in the eastern hemisphere, but the taxon referred to as var. saxitilis in North America is given a new name and Central Asia, but is actually most closely related to J. c. var. depressa from North America. To reflect

Adams, Robert P.

320

Simple Hu man coder PROC insert.new.node( VAR new.node, VALUE weight.of.new.node,  

E-print Network

.tree(VALUE probability[]) = VAR left.limit, right.limit, weight[size.of.tree] : PROC construct.leaves = -- buildSimple Hu#11;man coder PROC insert.new.node( VAR new.node, VALUE weight.of.new.node, VAR left.limit, VALUE right.limit ) PROC construct.tree(VALUE probability[]) PROC construct.leaves -- build the leaves

Jones, Geraint

321

A co-CRISPR strategy for efficient genome editing in Caenorhabditis elegans.  

PubMed

Genome editing based on CRISPR (clustered regularly interspaced short palindromic repeats)-associated nuclease (Cas9) has been successfully applied in dozens of diverse plant and animal species, including the nematode Caenorhabditis elegans. The rapid life cycle and easy access to the ovary by micro-injection make C. elegans an ideal organism both for applying CRISPR-Cas9 genome editing technology and for optimizing genome-editing protocols. Here we report efficient and straightforward CRISPR-Cas9 genome-editing methods for C. elegans, including a Co-CRISPR strategy that facilitates detection of genome-editing events. We describe methods for detecting homologous recombination (HR) events, including direct screening methods as well as new selection/counterselection strategies. Our findings reveal a surprisingly high frequency of HR-mediated gene conversion, making it possible to rapidly and precisely edit the C. elegans genome both with and without the use of co-inserted marker genes. PMID:24879462

Kim, Heesun; Ishidate, Takao; Ghanta, Krishna S; Seth, Meetu; Conte, Darryl; Shirayama, Masaki; Mello, Craig C

2014-08-01

322

Analysis of the swimming-to-crawling transition of Caenorhabditis elegans in viscous fluid  

E-print Network

The locomotory behavior of the nematode Caenorhabditis elegans is often characterized by two distinct gaits - swimming when in fluids and crawling when on surfaces. Swimming is characterized by about a twice greater ...

Kawai, Risa

2008-01-01

323

Ligand-Gated Chloride Channels Are Receptors for Biogenic Amines in C. elegans  

E-print Network

Biogenic amines such as serotonin and dopamine are intercellular signaling molecules that function widely as neurotransmitters and neuromodulators. We have identified in the nematode Caenorhabditis elegans three ligand-gated ...

Ringstad, Niels

324

The TFEB orthologue HLH-30 regulates autophagy and modulates longevity in Caenorhabditis elegans.  

PubMed

Autophagy is a cellular recycling process that has an important anti-aging role, but the underlying molecular mechanism is not well understood. The mammalian transcription factor EB (TFEB) was recently shown to regulate multiple genes in the autophagy process. Here we show that the predicted TFEB orthologue HLH-30 regulates autophagy in Caenorhabditis elegans and, in addition, has a key role in lifespan determination. We demonstrate that hlh-30 is essential for the extended lifespan of Caenorhabditis elegans in six mechanistically distinct longevity models, and overexpression of HLH-30 extends lifespan. Nuclear localization of HLH-30 is increased in all six Caenorhabditis elegans models and, notably, nuclear TFEB levels are augmented in the livers of mice subjected to dietary restriction, a known longevity-extending regimen. Collectively, our results demonstrate a conserved role for HLH-30 and TFEB in autophagy, and possibly longevity, and identify HLH-30 as a uniquely important transcription factor for lifespan modulation in Caenorhabditis elegans. PMID:23925298

Lapierre, Louis R; De Magalhaes Filho, C Daniel; McQuary, Philip R; Chu, Chu-Chiao; Visvikis, Orane; Chang, Jessica T; Gelino, Sara; Ong, Binnan; Davis, Andrew E; Irazoqui, Javier E; Dillin, Andrew; Hansen, Malene

2013-01-01

325

Receptor-type guanylate cyclase is required for carbon dioxide sensation by Caenorhabditis elegans  

E-print Network

CO2 [CO subscript 2] is both a critical regulator of animal physiology and an important sensory cue for many animals for host detection, food location, and mate finding. The free-living soil nematode Caenorhabditis elegans ...

Hallem, Elissa A.

326

Evaluation of the influence of fullerenol on aging and stress resistance using Caenorhabditis elegans.  

PubMed

Fullerene derivatives have attracted extensive attention in biomedical fields and polyhydroxyl fullerene (fullerenol), a water-soluble fullerene derivative, is demonstrated as a powerful antioxidant. To further assess their anti-aging and anti-stress potential, we employed Caenorhabditis elegans (C. elegans) as a model organism to evaluate the effects of fullerenol on the growth, development, behavior and anti-stress ability in vivo. The data show that fullerenol has no obviously toxic effect on nematodes and can delay C. elegans aging progress under normal condition. Further studies demonstrate that fullerenol attenuates endogenous levels of reactive oxygen species and provides protection to C. elegans under stress conditions by up-regulating stress-related genes in a DAF-16 depend manner and improving lifespan. In summary, our data suggest that fullerenol might be a safe and reasonable anti-aging candidate with great potential in vivo. PMID:25542795

Cong, Wenshu; Wang, Peng; Qu, Ying; Tang, Jinglong; Bai, Ru; Zhao, Yuliang; Chunying Chen; Bi, Xiaolin

2015-02-01

327

A Co-CRISPR Strategy for Efficient Genome Editing in Caenorhabditis elegans  

PubMed Central

Genome editing based on CRISPR (clustered regularly interspaced short palindromic repeats)-associated nuclease (Cas9) has been successfully applied in dozens of diverse plant and animal species, including the nematode Caenorhabditis elegans. The rapid life cycle and easy access to the ovary by micro-injection make C. elegans an ideal organism both for applying CRISPR-Cas9 genome editing technology and for optimizing genome-editing protocols. Here we report efficient and straightforward CRISPR-Cas9 genome-editing methods for C. elegans, including a Co-CRISPR strategy that facilitates detection of genome-editing events. We describe methods for detecting homologous recombination (HR) events, including direct screening methods as well as new selection/counterselection strategies. Our findings reveal a surprisingly high frequency of HR-mediated gene conversion, making it possible to rapidly and precisely edit the C. elegans genome both with and without the use of co-inserted marker genes. PMID:24879462

Kim, Heesun; Ishidate, Takao; Ghanta, Krishna S.; Seth, Meetu; Conte, Darryl; Shirayama, Masaki; Mello, Craig C.

2014-01-01

328

Abl Kinase Inhibits the Engulfment of Apoptotic [corrected] Cells in Caenorhabditis elegans  

E-print Network

The engulfment of apoptotic cells is required for normal metazoan development and tissue remodeling. In Caenorhabditis elegans, two parallel and partially redundant conserved pathways act in cell-corpse engulfment. One ...

Hurwitz, Michael Eliezer

329

Receptors and Other Signaling Proteins Required for Serotonin Control of Locomotion in Caenorhabditis elegans  

E-print Network

A better understanding of the molecular mechanisms of signaling by the neurotransmitter serotonin is required to assess the hypothesis that defects in serotonin signaling underlie depression in humans. Caenorhabditis elegans ...

Gustafson, Megan A.

330

The neuromolecular mechanisms that coordinate food availability with C. elegans male sexual behavior  

E-print Network

Organisms must coordinate behavioral and physiological responses to changingenvironmental conditions. In the nematode C. elegans, the presence or absence of foodin the environment affects many metabolic and behavioral responses, including...

Gruninger, Todd Ryan

2009-05-15

331

Many families of Caenorhabditis elegans microRNAs are not essential for development or viability  

E-print Network

MicroRNAs (miRNAs) are approximately 23 nt regulatory RNAs that posttranscriptionally inhibit the functions of protein-coding mRNAs. We previously found that most C. elegans miRNAs are individually not essential for ...

Alvarez-Saavedra, Ezequiel

332

C. elegans integrates food, stress, and hunger signals to coordinate motor activity  

E-print Network

In the presence of a bacterial food source, the small nematode C. elegans greatly reduces its rate of locomotion. While mechanical agitation greatly stimulates the locomotion of well-fed animals on bacteria, it does not ...

Omura, Daniel Togo

2008-01-01

333

Alpha-Synuclein Disrupted Dopamine Homeostasis Leads to Dopaminergic Neuron Degeneration in Caenorhabditis elegans  

E-print Network

Disruption of dopamine homeostasis may lead to dopaminergic neuron degeneration, a proposed explanation for the specific vulnerability of dopaminergic neurons in Parkinson's disease. While expression of human ?-synuclein in C. elegans results...

Cao, Pengxiu; Yuan, Yiyuan; Pehek, Elizabeth A.; Moise, Alexander R.; Huang, Ying; Palczewski, Krzysztof; Feng, Zhaoyang

2010-02-19

334

Integration of Caenorhabditis elegans MAPK pathways mediating immunity and stress resistance  

E-print Network

Integration of Caenorhabditis elegans MAPK pathways mediating immunity and stress resistance by MEK mediating immunity and heavy metal stress by common MAPKK and MKP signaling components suggests pivotal processes, including development, growth and proliferation, stress responses, and immunity. MAPK acti

Ausubel, Frederick M.

335

A Movable Surface: Formation of Yersinia sp. Biofilms on Motile Caenorhabditis elegans  

PubMed Central

Bubonic plague is transmitted by fleas whose feeding is blocked by a mass of Yersinia pestis in the digestive tract. Y. pestis and the closely related Y. pseudotuberculosis also block the feeding of Caenorhabditis elegans by forming a biofilm on the nematode head. C. elegans mutants with severe motility defects acquire almost no biofilm, indicating that normal animals accumulate the biofilm matrix as they move through a Yersinia lawn. Using the lectin wheat germ agglutinin as a probe, we show that the matrix on C. elegans contains carbohydrate produced by Yersinia. The carbohydrate is present in bacterial lawns prior to addition of nematodes, indicating that biofilm formation does not involve signaling between the two organisms. Furthermore, biofilm accumulation depends on continuous C. elegans exposure to a lawn of Yersinia bacteria. PMID:15262945

Tan, Li; Darby, Creg

2004-01-01

336

SPK-1, an SR protein kinase, inhibits programmed cell death in Caenorhabditis elegans  

E-print Network

To identify genes involved in protecting cells from programmed cell death in Caenorhabditis elegans, we performed a genetic screen to isolate mutations that cause an increase in the number of programmed cell deaths. We ...

Galvin, Brendan D.

337

Monitoring the Clearance of Apoptotic and Necrotic Cells in the Nematode Caenorhabditis elegans  

PubMed Central

The nematode Caenorhabditis elegans is an excellent model organism for studying the mechanisms controlling cell death, including apoptosis, a cell suicide event, and necrosis, pathological cell deaths caused by environmental insults or genetic alterations. C. elegans has also been established as a model for understanding how dying cells are cleared from animal bodies. In particular, the transparent nature of worm bodies and eggshells make C. elegans particularly amenable for live-cell microscopy. Here we describe methods for identifying apoptotic and necrotic cells in living C. elegans embryos, larvae, and adults and for monitoring their clearance during development. We further discuss specific methods to distinguish engulfed from unengulfed apoptotic cells, and methods to monitor cellular and molecular events occurring during phagosome maturation. These methods are based on Differential Interference Contrast (DIC) microscopy or fluorescence microscopy using GFP-based reporters. PMID:23733578

Li, Zao; Lu, Nan; He, Xiangwei; Zhou, Zheng

2014-01-01

338

Sensory roles of neuronal cilia: Cilia development, morphogenesis, and function in C. elegans  

PubMed Central

In the free-living nematode Caenorhabditis elegans, cilia are found on the dendritic endings of sensory neurons. C. elegans cilia are classified as `primary' or `sensory' according to the `9+0' axonemal ultrastiucture (nine doublet outer microtubules with no central microtubule pair) and lack of motility, characteristics of `9+2' cilia. The C. elegans ciliated nervous system allows the animal to perceive environmental stimuli and make appropriate developmental, physiological, and behavioral decisions. In vertebrates, the biological significance of primary cilia had been largely neglected. Recent findings have placed primary/sensory cilia in the center of cellular signaling and developmental processes. Studies using genetic model organisms such as C. elegans identified the link between ciliary dysfunction and human ciliopathies. Future studies in the worm will address important basic questions regarding ciliary development, morphogenesis, specialization, and signaling functions. PMID:18508635

Bae, Young-Kyung; Barr, Maureen M.

2011-01-01

339

Mechanisms of Mating-Behavior Deterioration in Early Aging Male C. elegans  

E-print Network

Aging has been a subject of interest throughout history. Scientific studies have focused on lifespan regulation, but ignored many other aspects of aging such as behavioral decline. Research using the model organism C. elegans has contributed...

Guo, Xiaoyan

2014-08-06

340

The Retrograde IFT Machinery of C. elegans Cilia: Two IFT Dynein Complexes?  

Microsoft Academic Search

We analyzed the relatively poorly understood IFT-dynein (class DYNC2)-driven retrograde IFT pathway in C. elegans cilia, which yielded results that are surprising in the context of current models of IFT. Assays of C. elegans dynein gene expression and intraflagellar transport (IFT) suggest that conventional IFT-dynein contains essential heavy (CHE-3), light-intermediate (XBX-1), plus three light polypeptide chains that participate in IFT,

Limin Hao; Evgeni Efimenko; Peter Swoboda; Jonathan M. Scholey

2011-01-01

341

An Abundant Class of Tiny RNAs with Probable Regulatory Roles in Caenorhabditis elegans  

Microsoft Academic Search

Two small temporal RNAs (stRNAs), lin-4 and let-7, control developmental timing in Caenorhabditis elegans. We find that these two regulatory RNAs are members of a large class of 21- to 24-nucleotide noncoding RNAs, called microRNAs (miRNAs). We report on 55 previously unknown miRNAs in C. elegans. The miRNAs have diverse expression patterns during development: a let-7 paralog is temporally coexpressed

Nelson C. Lau; Lee P. Lim; Earl G. Weinstein; David P. Bartel

2001-01-01

342

Role of bacteria in larval settlement and metamorphosis of the polychaete Hydroides elegans  

Microsoft Academic Search

The serpulid polychaete Hydroides elegans Haswell, 1883 is an early colonist of new substrata in Pearl Harbor, Oahu, Hawaii. When metamorphically competent, larvae\\u000a of H. elegans will settle rapidly upon an acceptably biofilmed surface, but not on a clean surface. In this study we found the ability\\u000a of larvae to respond selectively to inductive surfaces to be retained for at

C. R. C. Unabia; M. G. Hadfield

1999-01-01

343

Mutants carrying two sma mutations are super small in the nematode C. elegans  

Microsoft Academic Search

Body size determination is critical for multicellular organisms; however, the mechanisms remain largely unknown. Mutations that alter body size were studied to solve the mechanisms, for exam- ple, in mouse, fruit fly and the nematode Caenorhabditis elegans. In C. elegans, a large mutant and several small body size (sma) mutants are known. Of the latter, sma-2, sma-3, sma-4, sma-6, dbl-1

Naoharu Watanabe; Takeshi Ishihara; Yasumi Ohshima

2007-01-01

344

C. Elegans Model for Studying Tropomyosin and Troponin Regulations of Muscle Contraction and Animal Behavior  

Microsoft Academic Search

There are two muscle tissues in the nematode Caenorhabditis elegans: the pharynx for feeding and the body wall for locomotion. These correspond to cardiac and skeletal muscles in vertebrates,\\u000a respectively. Study of the muscle genes of C. elegans can be classified into three stages; first, mutant isolation and gene mapping, second, cloning and sequencing of the gene,\\u000a and third, complete

Hiroaki Kagawa; Tomohide Takaya; Razia Ruksana; Frederick Anokye-Danso; Hiromi Terami

345

Expression of Human beta-Amyloid Peptide in Transgenic Caenorhabditis elegans  

Microsoft Academic Search

Transgenic Caenorhabditis elegans nematodes have been engineered to express potentially amyloidic human proteins. These animals contain constructs in which the muscle-specific unc-54 promoter\\/enhancer of C. elegans drives the expression of the appropriate coding regions derived from human cDNA clones. Animals containing constructs expressing the 42-amino acid beta-amyloid peptide (derived from human amyloid precursor protein cDNA) produce muscle-specific deposits immunoreactive with

Christopher D. Link

1995-01-01

346

THE GENE STRUCTURES OF SPONTANEOUS MUTATIONS AFFECTING A CAENORHABDZTZS ELEGANS MYOSIN HEAVY CHAIN GENE  

Microsoft Academic Search

We have isolated spontaneous mutations affecting the unc-54 major myosin heavy chain gene of Caenorhabditis elegans (variety Bristol). Spontaneous unc- 54 mutants occur in C. elegans populations at a frequency of approximately 3 X We have studied the gene structure of 65 independent unc-54 muta- tions using filter-transfer hybridization techniques. Most unc-54 mutations (50 of 65) exhibit no abnormalities detected

DAVID EIDE; PHILIP ANDERSON

347

A proteomic view of Caenorhabditis elegans caused by short-term hypoxic stress  

Microsoft Academic Search

BACKGROUND: The nematode Caenorhabditis elegans is both sensitive and tolerant to hypoxic stress, particularly when the evolutionarily conserved hypoxia response pathway HIF-1\\/EGL-9\\/VHL is involved. Hypoxia-induced changes in the expression of a number of genes have been analyzed using whole genome microarrays in C. elegans, but the changes at the protein level in response to hypoxic stress still remain unclear. RESULTS:

Hualing Li; Changhong Ren; Jinping Shi; Xingyi Hang; Feilong Zhang; Yan Gao; Yonghong Wu; Langlai Xu; Changsheng Chen; Chenggang Zhang

2010-01-01

348

Expression of a Drosophila melanogaster amber suppressor tRNA Ser in Caenorhabditis elegans  

Microsoft Academic Search

The purpose of this study was to test a cloned amber-suppressing tRNASer gene derived from Drosophila melanogaster for its ability to produce amber suppression in the nematode Caenorhabditis elegans. To date, all characterized nonsense suppressors in C. elegans have been derived from tRNATrp genes. Suppression was assayed by monitoring the reversal of a mutant tra-3 phenotype among individuals transformed with

David B. Pilgrim; John B. Bell

1993-01-01

349

A systematic RNAi screen identifies a critical role for mitochondria in C. elegans longevity  

Microsoft Academic Search

We report a systematic RNA interference (RNAi) screen of 5,690 Caenorhabditis elegans genes for gene inactivations that increase lifespan. We found that genes important for mitochondrial function stand out as a principal group of genes affecting C. elegans lifespan. A classical genetic screen identified a mutation in the mitochondrial leucyl-tRNA synthetase gene (lrs-2) that impaired mitochondrial function and was associated

Siu Sylvia Lee; Raymond Y. N. Lee; Andrew G. Fraser; Ravi S. Kamath; Julie Ahringer; Gary Ruvkun

2002-01-01

350

A conserved checkpoint monitors meiotic chromosome synapsis inCaenorhabditis elegans  

SciTech Connect

We report the discovery of a checkpoint that monitorssynapsis between homologous chromosomes to ensure accurate meioticsegregation. Oocytes containing unsynapsed chromosomes selectivelyundergo apoptosis even if agermline DNA damage checkpoint is inactivated.This culling mechanism isspecifically activated by unsynapsed pairingcenters, cis-acting chromosomesites that are also required to promotesynapsis in Caenorhabditis elegans. Apoptosis due to synaptic failurealso requires the C. elegans homolog of PCH2,a budding yeast pachytenecheckpoint gene, which suggests that this surveillance mechanism iswidely conserved.

Bhalla, Needhi; Dernburg, Abby F.

2005-07-14

351

Microarray analysis of global gene expression in Caenorhabditis elegans exposed to potassium dichromate  

Microsoft Academic Search

Hexavalent chromium [Cr (VI)] can be considered as carcinogen heavy metal to human population. Especially, potassium dichromate\\u000a [K2Cr2O7; Cr (VI)] induces DNA damage response and oxidative stress. It also causes inhibition of protective process including DNA\\u000a repair as well as apoptosis. However, genomic responses to Cr (VI) exposure in Caenorhabditis elegans (C. elegans) have not been performed yet. As an

Seok Won Jeong; Hye Lim Kim; Young Rok Seo

2011-01-01

352

The Role of sdc-1 in the Sex Determination and Dosage Compensation Decisions in Caenorhabditis elegans  

Microsoft Academic Search

Our previous work demonstrated that mutations in the X-linked gene sdc-J disrupt both sex determination and dosage compensation in Caenorhabditis elegans XX animals, suggesting that sdc-J acts at a step that is shared by the sex determination and dosage compensation pathways prior to their divergence. In this report, we extend our understanding of early events in C. elegans sex determination

Anne M. Villeneuve; Barbara J. Meyer

1990-01-01

353

Locomotion and Body Shape Changes of Metabolically Different C.elegans in Fluids with Varying Viscosities  

NASA Astrophysics Data System (ADS)

Caenorhabditis elegans (C.elegans) are soil dwelling roundworms that have served as model organisms for studying a multitude of biological and engineering phenomena. On agar, the locomotion of the worm is sinusoidal, while in water, the swimming motion of the worm appears more episodic. The efficiency of the worm locomotion is tested by placing the worm in four fluids with varying viscosities. We quantify the locomotion pattern variations by categorizing the swimming kinematics and shapes of the C.elegans. The locomotion of two mutants C.elegans and a control C.elegans was tested: daf2, nhr49, and N2 Wildtype. The metabolic effects of the worms are evaluated by focusing on the forward swimming velocity, wavelength, amplitude and swimming frequency were compared. Using these measured values, we were able to quantify the efficiency, the speed of propagation of the wave along the body resulting in forward movement (wave velocity), and transverse velocity, defined as the amplitude times the frequency, of the worm locomotion. It was shown that C.elegans has a preferential swimming shape that adapts as the environment changes regardless of its efficiency.

Wong, Rachel; Brenowitz, Noah; Shen, Amy

2010-11-01

354

Physiological and Immunological Regulations in Caenorhabditis elegans Infected with Salmonella enterica serovar Typhi.  

PubMed

Studies pertaining to Salmonella enterica serovar Typhimurium infection by utilizing model systems failed to mimic the essential aspects of immunity induced by Salmonella enterica serovar Typhi, as the determinants of innate immunity are distinct. The present study investigated the physiological and innate immune responses of S. Typhi infected Caenorhabditis elegans and also explored the Ty21a mediated immune enhancement in C. elegans. Ty21a is a known live vaccine for typhoidal infection in human beings. Physiological responses of C. elegans infected with S. Typhi assessed by survival and behavioral assays revealed that S. Typhi caused host mortality by persistent infection. However, Ty21a exposure to C. elegans was not harmful. Ty21a pre-exposed C. elegans, exhibited significant resistance against S. Typhi infection. Elevated accumulation of S. Typhi inside the infected host was observed when compared to Ty21a exposures. Transcript analysis of candidate innate immune gene (clec-60, clec-87, lys-7, ilys-3, scl-2, cpr-2, F08G5.6, atf-7, age-1, bec-1 and daf-16) regulations in the host during S. Typhi infection have been assessed through qPCR analysis to understand the activation of immune signaling pathways during S. Typhi infections. Gene silencing approaches confirmed that clec-60 and clec-87 has a major role in the defense system of C. elegans during S. Typhi infection. In conclusion, the study revealed that preconditioning of host with Ty21a protects against subsequent S. Typhi infection. PMID:24426167

Sivamaruthi, Bhagavathi Sundaram; Balamurugan, Krishnaswamy

2014-03-01

355

Solution structure of CEH-37 homeodomain of the nematode Caenorhabditis elegans  

SciTech Connect

Highlights: •We have determined solution structures of CEH-37 homedomain. •CEH-37 HD has a compact ?-helical structure with HTH DNA binding motif. •Solution structure of CEH-37 HD shares its molecular topology with that of the homeodomain proteins. •Residues in the N-terminal region and HTH motif are important in binding to Caenorhabditis elegans telomeric DNA. •CEH-37 could play an important role in telomere function via DNA binding. -- Abstract: The nematode Caenorhabditis elegans protein CEH-37 belongs to the paired OTD/OTX family of homeobox-containing homeodomain proteins. CEH-37 shares sequence similarity with homeodomain proteins, although it specifically binds to double-stranded C. elegans telomeric DNA, which is unusual to homeodomain proteins. Here, we report the solution structure of CEH-37 homeodomain and molecular interaction with double-stranded C. elegans telomeric DNA using nuclear magnetic resonance (NMR) spectroscopy. NMR structure shows that CEH-37 homeodomain is composed of a flexible N-terminal region and three ?-helices with a helix-turn-helix (HTH) DNA binding motif. Data from size-exclusion chromatography and fluorescence spectroscopy reveal that CEH-37 homeodomain interacts strongly with double-stranded C. elegans telomeric DNA. NMR titration experiments identified residues responsible for specific binding to nematode double-stranded telomeric DNA. These results suggest that C. elegans homeodomain protein, CEH-37 could play an important role in telomere function via DNA binding.

Moon, Sunjin [Structural Biochemistry and Molecular Biophysics Lab, Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749 (Korea, Republic of)] [Structural Biochemistry and Molecular Biophysics Lab, Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749 (Korea, Republic of); Lee, Yong Woo; Kim, Woo Taek [Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749 (Korea, Republic of)] [Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749 (Korea, Republic of); Lee, Weontae, E-mail: wlee@spin.yonsei.ac.kr [Structural Biochemistry and Molecular Biophysics Lab, Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749 (Korea, Republic of)] [Structural Biochemistry and Molecular Biophysics Lab, Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749 (Korea, Republic of)

2014-01-10

356

Caenorhabditis elegans RNA-processing Protein TDP-1 Regulates Protein Homeostasis and Life Span*?  

PubMed Central

Transactive response DNA-binding protein (TARDBP/TDP-43), a heterogeneous nuclear ribonucleoprotein (hnRNP) with diverse activities, is a common denominator in several neurodegenerative disorders, including amyotrophic lateral sclerosis and frontotemporal lobar degeneration. Orthologs of TDP-43 exist in animals ranging from mammals to invertebrates. Here, we systematically studied mutant Caenorhabditis elegans lacking the nematode TDP-43 ortholog, TDP-1. Heterologous expression of human TDP-43 rescued the defects in C. elegans lacking TDP-1, suggesting their functions are conserved. Although the tdp-1 mutants exhibited deficits in fertility, growth, and locomotion, loss of tdp-1 attenuated defects in several C. elegans models of proteotoxicity. Loss of tdp-1 suppressed defects in transgenic C. elegans expressing TDP-43 or CuZn superoxide dismutase, both of which are associated with proteotoxicity in neurodegenerative diseases. Loss of tdp-1 also reduced defects in mutant animals lacking the heat shock factor HSF-1. Transcriptional profiling demonstrated that the loss of TDP-1 altered expression of genes functioning in RNA processing and protein folding. Furthermore, the absence of tdp-1 extended the life span in C. elegans. The life span extension required a FOXO transcriptional factor DAF-16 but not HSF-1. These results suggest that the C. elegans TDP-1 has a role in the regulation of protein homeostasis and aging. PMID:22232551

Zhang, Tao; Hwang, Ho-Yon; Hao, Haiping; Talbot, Conover; Wang, Jiou

2012-01-01

357

Effect of nanoparticles on the biochemical and behavioral aging phenotype of the nematode Caenorhabditis elegans.  

PubMed

Invertebrate animal models such as the nematode Caenorhabditis elegans (C. elegans) are increasingly used in nanotechnological applications. Research in this area covers a wide range from remote control of worm behavior by nanoparticles (NPs) to evaluation of organismal nanomaterial safety. Despite of the broad spectrum of investigated NP-bio interactions, little is known about the role of nanomaterials with respect to aging processes in C. elegans. We trace NPs in single cells of adult C. elegans and correlate particle distribution with the worm's metabolism and organ function. By confocal microscopy analysis of fluorescently labeled NPs in living worms, we identify two entry portals for the uptake of nanomaterials via the pharynx to the intestinal system and via the vulva to the reproductive system. NPs are localized throughout the cytoplasm and the cell nucleus in single intestinal, and vulval B and D cells. Silica NPs induce an untimely accumulation of insoluble ubiquitinated proteins, nuclear amyloid and reduction of pharyngeal pumping that taken together constitute a premature aging phenotype of C. elegans on the molecular and behavioral level, respectively. Screening of different nanomaterials for their effects on protein solubility shows that polystyrene or silver NPs do not induce accumulation of ubiquitinated proteins suggesting that alteration of protein homeostasis is a unique property of silica NPs. The nematode C. elegans represents an excellent model to investigate the effect of different types of nanomaterials on aging at the molecule, cell, and whole organism level. PMID:24256469

Scharf, Andrea; Piechulek, Annette; von Mikecz, Anna

2013-12-23

358

Realgar bioleaching solution suppress ras excessive activation by increasing ROS in Caenorhabditis elegans.  

PubMed

Although realgar bioleaching solution (RBS) has been proved to be a potential candidate for cancer therapy, the mechanisms of RBS anticancer are still far from being completely understood. Dosed with RBS in C. elegans, the multivulva phenotype resulting from oncogenic ras gain-of-function was inhibited in a dose dependent manner. It could be abrogated by concurrent treatment C. elegans with RBS and the radical scavenger DMSO. However, RBS could not induce DAF-16 nuclear translocation in TJ356 or the increase of HSP 16.2 expression in CL2070, which both could be aroused visible GFP fluorescent variation to represent for oxidative stress generation. Treatment C. elegans with superoxide anion generator paraquat, similar results were also obtained. Our results indicated that RBS suppress excessive activated ras by increasing reactive oxygen species (ROS) in C. elegans. Secondly, ROS induced by RBS significantly accumulated on a higher level in C. elegans with a mutational ras than that with wild ras, thus leading to oxidative stress on ras gain-of-function background rather than on normal ras context. Our results firstly demonstrated that using C. elegans as a model organism for evaluating prooxidant drug candidates for cancer therapy. PMID:23775476

Zhi, De Juan; Feng, Na; Liu, Dong Ling; Hou, Rong Li; Wang, Mei Zu; Ding, Xiao Xia; Li, Hong Yu

2014-03-01

359

Stimulation of Host Immune Defenses by a Small Molecule Protects C. elegans from Bacterial Infection  

PubMed Central

The nematode Caenorhabditis elegans offers currently untapped potential for carrying out high-throughput, live-animal screens of low molecular weight compound libraries to identify molecules that target a variety of cellular processes. We previously used a bacterial infection assay in C. elegans to identify 119 compounds that affect host-microbe interactions among 37,214 tested. Here we show that one of these small molecules, RPW-24, protects C. elegans from bacterial infection by stimulating the host immune response of the nematode. Using transcriptome profiling, epistasis pathway analyses with C. elegans mutants, and an RNAi screen, we show that RPW-24 promotes resistance to Pseudomonas aeruginosa infection by inducing the transcription of a remarkably small number of C. elegans genes (?1.3% of all genes) in a manner that partially depends on the evolutionarily-conserved p38 MAP kinase pathway and the transcription factor ATF-7. These data show that the immunostimulatory activity of RPW-24 is required for its efficacy and define a novel C. elegans–based strategy to identify compounds with activity against antibiotic-resistant bacterial pathogens. PMID:22719261

Pukkila-Worley, Read; Feinbaum, Rhonda; Kirienko, Natalia V.; Larkins-Ford, Jonah; Conery, Annie L.; Ausubel, Frederick M.

2012-01-01

360

Excessive folate synthesis limits lifespan in the C. elegans: E. coli aging model  

PubMed Central

Background Gut microbes influence animal health and thus, are potential targets for interventions that slow aging. Live E. coli provides the nematode worm Caenorhabditis elegans with vital micronutrients, such as folates that cannot be synthesized by animals. However, the microbe also limits C. elegans lifespan. Understanding these interactions may shed light on how intestinal microbes influence mammalian aging. Results Serendipitously, we isolated an E. coli mutant that slows C. elegans aging. We identified the disrupted gene to be aroD, which is required to synthesize aromatic compounds in the microbe. Adding back aromatic compounds to the media revealed that the increased C. elegans lifespan was caused by decreased availability of para-aminobenzoic acid, a precursor to folate. Consistent with this result, inhibition of folate synthesis by sulfamethoxazole, a sulfonamide, led to a dose-dependent increase in C. elegans lifespan. As expected, these treatments caused a decrease in bacterial and worm folate levels, as measured by mass spectrometry of intact folates. The folate cycle is essential for cellular biosynthesis. However, bacterial proliferation and C. elegans growth and reproduction were unaffected under the conditions that increased lifespan. Conclusions In this animal:microbe system, folates are in excess of that required for biosynthesis. This study suggests that microbial folate synthesis is a pharmacologically accessible target to slow animal aging without detrimental effects. PMID:22849329

2012-01-01

361

New saponins from the seeds of Agrostemma githago var. githago.  

PubMed

Two new saponins were isolated from the seeds of Agrostemma githago L. var. githago. On the basis of chemical and spectral evidence their structures were determined to be 3-O-beta-D-xylopyranosyl-(1-->3)-[beta-D-galactopyranosyl-(1-->2)]-beta- D- glucuronopyranosylgypsogenin-28-O-beta-D-xylopyranosyl-(1-->4)- [beta-D-glucopyranosyl-(1-->3)]-alpha-L-rhamnopyranosyl-(1-->2)-beta- D-4-O-acetylfucopyranoside and 3-O-beta-D-xylopyranosyl-(1-->3)- [beta-D-galactopyranosyl-(1-->2)]-beta-D-glucuronopyranosyl-gyp sogenin- 28-O-beta-D-xylopyranosyl-(1-->3)-beta-D-xylopyranosyl-(1-->4)- [beta-D-glucopyranosyl-(1-->3)]-alpha-L-rhamnopyranosyl-(1-->2)-beta-D- 4-O-acetylfucopyranoside. PMID:9525108

Siepmann, C; Bader, G; Hiller, K; Wray, V; Domke, T; Nimtz, M

1998-03-01

362

TILLING is an effective reverse genetics technique for Caenorhabditis elegans  

PubMed Central

Background TILLING (Targeting Induced Local Lesions in Genomes) is a reverse genetic technique based on the use of a mismatch-specific enzyme that identifies mutations in a target gene through heteroduplex analysis. We tested this technique in Caenorhabditis elegans, a model organism in which genomics tools have been well developed, but limitations in reverse genetics have restricted the number of heritable mutations that have been identified. Results To determine whether TILLING represents an effective reverse genetic strategy for C. elegans we generated an EMS-mutagenised population of approximately 1500 individuals and screened for mutations in 10 genes. A total of 71 mutations were identified by TILLING, providing multiple mutant alleles for every gene tested. Some of the mutations identified are predicted to be silent, either because they are in non-coding DNA or because they affect the third bp of a codon which does not change the amino acid encoded by that codon. However, 59% of the mutations identified are missense alleles resulting in a change in one of the amino acids in the protein product of the gene, and 3% are putative null alleles which are predicted to eliminate gene function. We compared the types of mutation identified by TILLING with those previously reported from forward EMS screens and found that 96% of TILLING mutations were G/C-to-A/T transitions, a rate significantly higher than that found in forward genetic screens where transversions and deletions were also observed. The mutation rate we achieved was 1/293 kb, which is comparable to the mutation rate observed for TILLING in other organisms. Conclusion We conclude that TILLING is an effective and cost-efficient reverse genetics tool in C. elegans. It complements other reverse genetic techniques in this organism, can provide an allelic series of mutations for any locus and does not appear to have any bias in terms of gene size or location. For eight of the 10 target genes screened, TILLING has provided the first genetically heritable mutations which can be used to study their functions in vivo. PMID:17049087

Gilchrist, Erin J; O'Neil, Nigel J; Rose, Ann M; Zetka, Monique C; Haughn, George W

2006-01-01

363

Genetic relationships and population structure of the endangered Steamboat buckwheat, Eriogonum ovalifolium var. williamsiae (Polygonaceae).  

PubMed

Eriogonum ovalifolium var. williamsiae (Steamboat buckwheat) is a narrow endemic subshrub, known from a single locality in Washoe County, Nevada. We examined genetic structure of the only known population by analyzing patterns of allozyme variation. Our results suggest that Steamboat buckwheat has high genetic variability, with levels of variation similar to that typical of a widespread species rather than a narrow endemic. Genotype frequencies suggest that mating is random. We detected no genetic subdivision of the population. Several clones spanning up to 67 cm were found, but we do not know if such clones are common. We used allozyme data to assess the genetic similarity of var. williamsiae to five other varieties of E. ovalifolium. All six varieties are very similar allozymically with var. williamsiae being the most similar to the widespread var. ovalifolium. Although var. williamsiae and var. ovalifolium are morphologically distinct, their genetic similarity warrants further study to determine whether or not they should be treated as separate taxa. Evidence of male sterility in var. williamsiae plus other data leads us to hypothesize that this taxon might be either a hybrid or undergoing cytoplasmic introgression. Information gathered from this study, in concert with ongoing work on the breeding system of Steamboat buckwheat, should be helpful in forming management strategies for this plant. PMID:11302845

Archibald, J K; Wolf, P G; Tepedino, V J; Bair, J

2001-04-01

364

Aberrant meiotic behavior in Agave tequilana Weber var. azul  

PubMed Central

Background Agave tequilana Weber var. azul, is the only one variety permitted by federal law in México to be used for tequila production which is the most popular contemporary alcoholic beverage made from agave and recognized worldwide. Despite the economic, genetic, and ornamental value of the plant, it has not been subjected to detailed cytogenetic research, which could lead to a better understanding of its reproduction for future genetic improvement. The objective of this work was to study the meiotic behavior in pollen mother cells and its implications on the pollen viability in Agave tequilana Weber var. azul. Results The analysis of Pollen Mother Cells in anaphase I (A-I) showed 82.56% of cells with a normal anaphase and, 17.44% with an irregular anaphase. In which 5.28% corresponded to cells with side arm bridges (SAB); 3.68% cells with one bridge and one fragment; 2.58% of irregular anaphase showed cells with one or two lagging chromosomes and 2.95% showed one acentric fragment; cells with two bridges and cells with two bridges and one acentric fragment were observed in frequencies of 1.60% and 1.35% respectively. In anaphase II some cells showed bridges and fragments too. Aberrant A-I cells had many shrunken or empty pollen grains (42.00%) and 58.00 % viable pollen. Conclusion The observed meiotic irregularities suggest that structural chromosome aberrations have occurred, such as heterozygous inversions, sister chromatid exchanges, deletions and duplications which in turn are reflected in a low pollen viability. PMID:12396234

Ruvalcaba-Ruiz, Domingo; Rodríguez-Garay, Benjamin

2002-01-01

365

Genetic and Molecular Characterization of Programmed Cell Death in the C.elegans Tail-Spike Cell.  

E-print Network

??Work in Caenorhabditis elegans has been instrumental in deciphering the molecular basis of programmed cell death. However, despite extensive characterization of broadacting cell death genes,… (more)

Waase-Maurer, Carine

2007-01-01

366

Chromatin and transcriptional regulators act in a cascade to establish a bilateral asymmetry of the C. elegans nervous system  

E-print Network

Neuroanatomical bilateral asymmetry is a widespread feature in both vertebrates and invertebrates. Although mostly bilaterally symmetric, the nervous system of Caenorhabditis elegans displays bilateral asymmetry. Bilateral ...

Nakano, Shunji, Ph. D. Massachusetts Institute of Technology

2011-01-01

367

Iron promotes protein insolubility and aging in C. elegans  

PubMed Central

Many late-onset proteotoxic diseases are accompanied by a disruption in homeostasis of metals (metallostasis) including iron, copper and zinc. Although aging is the most prominent risk factor for these disorders, the impact of aging on metallostasis and its role in proteotoxic disease remain poorly understood. Moreover, it is not clear whether a loss of metallostasis influences normal aging. We have investigated the role of metallostasis in longevity of Caenorhabditis elegans. We found that calcium, copper, iron, and manganese levels increase as a function of age, while potassium and phosphorus levels tend to decrease. Increased dietary iron significantly accelerated the age-related accumulation of insoluble protein, a molecular pathology of aging. Proteomic analysis revealed widespread effects of dietary iron in multiple organelles and tissues. Pharmacological interventions to block accumulation of specific metals attenuated many models of proteotoxicity and extended normal lifespan. Collectively, these results suggest that a loss of metallostasis with aging contributes to age-related protein aggregation. PMID:25554795

Klang, Ida M.; Schilling, Birgit; Sorensen, Dylan J.; Sahu, Alexandria K.; Kapahi, Pankaj; Andersen, Julie K.; Swoboda, Peter; Killilea, David W.; Gibson, Bradford W.; Lithgow, Gordon J.

2014-01-01

368

Is dauer pheromone of Caenorhabditis elegans really a pheromone?  

NASA Astrophysics Data System (ADS)

Animals respond to signals and cues in their environment. The difference between a signal (e.g. a pheromone) and a cue (e.g. a waste product) is that the information content of a signal is subject to natural selection, whereas that of a cue is not. The model free-living nematode Caenorhabditis elegans forms an alternative developmental morph (the dauer larva) in response to a so-called `dauer pheromone', produced by all worms. We suggest that the production of `dauer pheromone' has no fitness advantage for an individual worm and therefore we propose that `dauer pheromone' is not a signal, but a cue. Thus, it should not be called a pheromone.

Viney, M. E.; Franks, N. R.

369

Radiation-induced gene expression in the nematode Caenorhabditis elegans  

NASA Technical Reports Server (NTRS)

We used the nematode C. elegans to characterize the genotoxic and cytotoxic effects of ionizing radiation in a simple animal model emphasizing the unique effects of charged particle radiation. Here we demonstrate by RT-PCR differential display and whole genome microarray hybridization experiments that gamma rays, accelerated protons and iron ions at the same physical dose lead to unique transcription profiles. 599 of 17871 genes analyzed (3.4%) showed differential expression 3 hrs after exposure to 3 Gy of radiation. 193 were up-regulated, 406 were down-regulated and 90% were affected only by a single species of radiation. A novel statistical clustering technique identified the regulatory relationships between the radiation-modulated genes and showed that genes affected by each radiation species were associated with unique regulatory clusters. This suggests that independent homeostatic mechanisms are activated in response to radiation exposure as a function of track structure or ionization density.

Nelson, Gregory A.; Jones, Tamako A.; Chesnut, Aaron; Smith, Anna L.

2002-01-01

370

Controlling neural activity in Caenorhabditis elegans to evoke chemotactic behavior  

NASA Astrophysics Data System (ADS)

Animals locate and track chemoattractive gradients in the environment to find food. With its simple nervous system, Caenorhabditis elegans is a good model system in which to understand how the dynamics of neural activity control this search behavior. To understand how the activity in its interneurons coordinate different motor programs to lead the animal to food, here we used optogenetics and new optical tools to manipulate neural activity directly in freely moving animals to evoke chemotactic behavior. By deducing the classes of activity patterns triggered during chemotaxis and exciting individual neurons with these patterns, we identified interneurons that control the essential locomotory programs for this behavior. Notably, we discovered that controlling the dynamics of activity in just one interneuron pair was sufficient to force the animal to locate, turn towards and track virtual light gradients.

Kocabas, Askin; Shen, Ching-Han; Guo, Zengcai V.; Ramanathan, Sharad

2013-03-01

371

In vitro biological screening of the stem of Desmodium elegans  

PubMed Central

Objective To explore the medicinal importance of the stem of Desmodium elegans, methanolic extract, and its different solvent fractions were evaluated for brine shrimp lethality, insecticidal and phytotoxicity, antifungal, and antibacterial activities. Methods The methanolic extract and its solvent fractions were tested for cytotoxic, phytotoxic, insecticidal, antifungal, and antibacterial effects using our previous published protocols. Results The methanolic, DCM, ethyl acetate and n-butanol fractions exhibited insecticidal effect against Callosobruchus analis and Rhyzopertha dominic. The methanolic extract, n-hexane, DCM ethyl acetate and n-butanol showed 75, 85, 85, 65 and 5% phytotoxicity at the tested concentration of 500 µg/mL respectively. The solvent fractions (DCM and ethyl acetate) were effective against F. solani (10% and 20% inhibition respectively). All the tested samples were devoid of cytotoxic and antibacterial effects. Conclusion It was concluded that this plant can be practiced for control of weeds and insects. PMID:23998011

Khan, Arshad; Usman, Rabia; Rauf, Abdur; Wang, Ming-Liang; Muhammad, Naveed; Aman, Akhatar; Tahir, Taha Hussein Musa

2013-01-01

372

Beta-glucuronidase mutants of the nematode Caenorhabditis elegans.  

PubMed

Using a screening procedure that is based on a histochemical stain for the enzyme beta-glucuronidase, we have isolated several mutants of the nematode Caenorhabditis elegans affected in beta-glucuronidase activity. All of the mutations fall into one complementation group and identify a new gene, gus-1, which has been mapped on the right arm of linkage group I (LG I), 1.1 map units to the left of unc-54. The mutants have no visible phenotype, and their viabilities and fertilities are unaffected. Linked revertants of two of the mutations have been isolated. They restore enzyme activity to almost wild-type levels; the beta-glucuronidase that one of the revertants produces differs from that of the wild type. We propose that gus-1 is the structural locus for beta-glucuronidase. PMID:3007276

Sebastiano, M; D'Alessio, M; Bazzicalupo, P

1986-03-01

373

Axon Regeneration Genes Identified by RNAi Screening in C. elegans  

PubMed Central

Axons of the mammalian CNS lose the ability to regenerate soon after development due to both an inhibitory CNS environment and the loss of cell-intrinsic factors necessary for regeneration. The complex molecular events required for robust regeneration of mature neurons are not fully understood, particularly in vivo. To identify genes affecting axon regeneration in Caenorhabditis elegans, we performed both an RNAi-based screen for defective motor axon regeneration in unc-70/?-spectrin mutants and a candidate gene screen. From these screens, we identified at least 50 conserved genes with growth-promoting or growth-inhibiting functions. Through our analysis of mutants, we shed new light on certain aspects of regeneration, including the role of ?-spectrin and membrane dynamics, the antagonistic activity of MAP kinase signaling pathways, and the role of stress in promoting axon regeneration. Many gene candidates had not previously been associated with axon regeneration and implicate new pathways of interest for therapeutic intervention. PMID:24403161

Nix, Paola; Hammarlund, Marc; Hauth, Linda; Lachnit, Martina; Jorgensen, Erik M.

2014-01-01

374

Optogenetic manipulation of neural activity in freely moving Caenorhabditis elegans  

PubMed Central

We present an optogenetic illumination system capable of real-time light delivery with high spatial resolution to specified targets in freely moving Caenorhabditis elegans. A tracking microscope records the motion of an unrestrained worm expressing Channelrhodopsin-2 or Halorhodopsin/NpHR in specific cell types. Image processing software analyzes the worm’s position within each video frame, rapidly estimates the locations of targeted cells, and instructs a digital micromirror device to illuminate targeted cells with laser light of the appropriate wavelengths to stimulate or inhibit activity. Since each cell in an unrestrained worm is a rapidly moving target, our system operates at high speed (~50 frames per second) to provide high spatial resolution (~30 µm). To demonstrate the accuracy, flexibility, and utility of our system, we present optogenetic analyses of the worm motor circuit, egg-laying circuit, and mechanosensory circuits that were not possible with previous methods. PMID:21240279

Leifer, Andrew M; Fang-Yen, Christopher; Gershow, Marc; Alkema, Mark J; Samuel, Aravinthan D T

2011-01-01

375

Neuropeptide signaling remodels chemosensory circuit composition in Caenorhabditis elegans  

PubMed Central

Neural circuits detect environmental changes and drive behavior. The routes of information flow through dense neural networks are dynamic; however, the mechanisms underlying this circuit flexibility are poorly understood. Here, we define a novel, sensory context-dependent and neuropeptide-regulated switch in the composition of a C. elegans salt sensory circuit. The primary salt detectors, ASE sensory neurons, use BLI-4 endoprotease-dependent cleavage to release the insulin-like peptide INS-6 in response to large but not small changes in external salt stimuli. Insulins, signaling through the insulin receptor DAF-2, functionally switch the AWC olfactory sensory neuron into an interneuron in the salt circuit. Animals with disrupted insulin signaling have deficits in salt attraction, suggesting that peptidergic signaling potentiates responses to high salt stimuli, which may promote ion homeostasis. Our results show that sensory context and neuropeptide signaling modify neural networks and suggest general mechanisms for generating flexible behavioral outputs by modulating neural circuit composition. PMID:24013594

Leinwand, Sarah G.; Chalasani, Sreekanth H.

2013-01-01

376

Dopamine Signaling Regulates Fat Content through ?-Oxidation in Caenorhabditis elegans  

PubMed Central

The regulation of energy balance involves an intricate interplay between neural mechanisms that respond to internal and external cues of energy demand and food availability. Compelling data have implicated the neurotransmitter dopamine as an important part of body weight regulation. However, the precise mechanisms through which dopamine regulates energy homeostasis remain poorly understood. Here, we investigate mechanisms through which dopamine modulates energy storage. We showed that dopamine signaling regulates fat reservoirs in Caenorhabditis elegans. We found that the fat reducing effects of dopamine were dependent on dopaminergic receptors and a set of fat oxidation enzymes. Our findings reveal an ancient role for dopaminergic regulation of fat and suggest that dopamine signaling elicits this outcome through cascades that ultimately mobilize peripheral fat depots. PMID:24465759

Barros, Alexandre Guimarães de Almeida; Bridi, Jessika Cristina; de Souza, Bruno Rezende; de Castro Júnior, Célio; de Lima Torres, Karen Cecília; Malard, Leandro; Jorio, Ado; de Miranda, Débora Marques; Ashrafi, Kaveh; Romano-Silva, Marco Aurélio

2014-01-01

377

Two new triterpenoids from Gelsemium elegans and Aglaia odorata.  

PubMed

Eleganoside A (1) and odoratanone A (15), a triterpenoid trisaccharide glycoside and a nortriterpenoid, together with twelve known compounds (2-13) and a mixture of cerebrosides (14) were isolated from Gelsemium elegans and Aglaia odorata. Their structures were elucidated by extensive spectroscopic and spectrometric analysis. Eleganoside A (1) features a 3-O-alpha-L-rhamnopyranosyl (1-->4)-beta-D-glucopyranosyl (1-->4)-beta-D-glucopyranoside of a peculiar 3,16-dihydroxyl-lanosta-8,24-dien-26-oic acid triterpenoid skeleton, and odoratanone A (15) is a 29-norcycloartane-type triterpenoid bearing an unusual five-membered methyl acetal ring. Anti-acetylcholinesterase/butyrylcholinesterase (AChE/BChE) assay indicated that at 50 microM, ethyl caffeate (5) was promising as a dual inhibitor of AChE and BChE, and paeonol (3) and 24-hydroperoxy-24-vinylcholesterol (9) exhibited BChE-selective inhibition. PMID:24354178

Liu, Bing; Yang, Lin; Xu, You-Kai; Liao, Shang-Gao; Luo, Huai-Rong; Na, Zhi

2013-10-01

378

High Resolution Map of Caenorhabditis elegans Gap Junction Proteins  

PubMed Central

The innexin family of gap junction proteins has 25 members in Caenorhabditis elegans. Here, we describe the first high-resolution expression map of all members through analysis of live worms transformed with green fluorescent protein under the control of entire promoter regions. Our analyses show that innexins have dynamic expression patterns throughout development and are found in virtually all cell types and tissues. Complex tissues, such as the pharynx, intestine, gonad, as well as scaffolding tissues and guidepost cells express a variety of innexins in overlapping or complementary patterns, suggesting they may form heteromeric and heterotypic channels. Innexin expression occurs in several types of cells that are not known to form gap junctions as well as in a pair of migrating cells, suggesting they may have hemichannel function. Therefore, innexins likely play roles in almost all body functions, including embryonic development, cell fate determination, oogenesis, egg laying, pharyngeal pumping, excretion, and locomotion. PMID:19621339

Altun, Zeynep F.; Chen, Bojun; Wang, Zhao-Weng; Hall, David H.

2009-01-01

379

Tissue-Specific Activities of SARM-ASK1-MKK3 Signaling Coordinate Immunity and Behavior to Pathogenic and Nutritional Bacteria in C. elegans  

E-print Network

Microbes represent both an essential source of nutrition and a potential source of lethal infection to the nematode Caenorhabditis elegans. Immunity in C. elegans requires a signaling module comprised of orthologs of the ...

Kim, Dennis H.

380

Evaluation of pesticide toxicities with differing mechanisms using Caenorhabditis elegans.  

PubMed

The aim of this study was to (1) determine whether model organism Caenorhabditis elegans was sensitive to pesticides at the maximum concentration limits regulated by national agency standards, and (2) examine the multi-biological toxicities occurring as a result of exposure to pesticides. Five pesticides, namely, chlorpyrifos, imibacloprid, buprofezin, cyhalothrin, and glyphosate, with four different mechanisms of action were selected for the investigation. In accordance with national agency requirements, 4 exposed groups were used for each tested pesticide with the concentration scales ranging from 1.0 x 10(-3) to 1 mg/L. L4 larvae were exposed for 24 and 72 h, respectively. Endpoints of locomotion, propagation, and development were selected for the assay as parameters of toxicity. After exposure for 24 h, both the body bend frequency and head thrash frequency of nematodes exposed to chlorpyrifos, imibacloprid, and cyhalothrin decreased in a concentration-dependent manner, and there were significant differences between exposed groups at maximum concentration level (MCL) compared to control. The generation time of nematodes exposed to buprofezin 24 h significantly increased in a concentration-dependent manner in the highest exposed group. When exposed for 72 h, the body bend frequency and head thrash frequency of nematodes exposed to cyhalothrin markedly decreased at MCL. The generation time and brood size of nematodes exposed to buprofezin were reduced in a concentration-dependent manner. The behavior of nematodes was sensitive to pesticides with neurotoxic properties, while pesticides affecting insect growth modified the reproductive system. The effects of pesticides on nematodes exposed for 24 h appeared more sensitive than with exposure for 72 h. Caenorhabditis elegans may thus be used for assessing the adverse effects of pesticide residues in aquatic environment. PMID:19492238

Ruan, Qin-Li; Ju, Jing-Juan; Li, Yun-Hui; Liu, Ran; Pu, Yue-Pu; Yin, Li-Hong; Wang, Da-Yong

2009-01-01

381

A global analysis of genetic interactions in Caenorhabditis elegans  

PubMed Central

Background Understanding gene function and genetic relationships is fundamental to our efforts to better understand biological systems. Previous studies systematically describing genetic interactions on a global scale have either focused on core biological processes in protozoans or surveyed catastrophic interactions in metazoans. Here, we describe a reliable high-throughput approach capable of revealing both weak and strong genetic interactions in the nematode Caenorhabditis elegans. Results We investigated interactions between 11 'query' mutants in conserved signal transduction pathways and hundreds of 'target' genes compromised by RNA interference (RNAi). Mutant-RNAi combinations that grew more slowly than controls were identified, and genetic interactions inferred through an unbiased global analysis of the interaction matrix. A network of 1,246 interactions was uncovered, establishing the largest metazoan genetic-interaction network to date. We refer to this approach as systematic genetic interaction analysis (SGI). To investigate how genetic interactions connect genes on a global scale, we superimposed the SGI network on existing networks of physical, genetic, phenotypic and coexpression interactions. We identified 56 putative functional modules within the superimposed network, one of which regulates fat accumulation and is coordinated by interactions with bar-1(ga80), which encodes a homolog of ?-catenin. We also discovered that SGI interactions link distinct subnetworks on a global scale. Finally, we showed that the properties of genetic networks are conserved between C. elegans and Saccharomyces cerevisiae, but that the connectivity of interactions within the current networks is not. Conclusions Synthetic genetic interactions may reveal redundancy among functional modules on a global scale, which is a previously unappreciated level of organization within metazoan systems. Although the buffering between functional modules may differ between species, studying these differences may provide insight into the evolution of divergent form and function. PMID:17897480

Byrne, Alexandra B; Weirauch, Matthew T; Wong, Victoria; Koeva, Martina; Dixon, Scott J; Stuart, Joshua M; Roy, Peter J

2007-01-01

382

Behavioral response of Caenorhabditis elegans to localized thermal stimuli  

PubMed Central

Background Nociception evokes a rapid withdrawal behavior designed to protect the animal from potential danger. C. elegans performs a reflexive reversal or forward locomotory response when presented with noxious stimuli at the head or tail, respectively. Here, we have developed an assay with precise spatial and temporal control of an infrared laser stimulus that targets one-fifth of the worm’s body and quantifies multiple aspects of the worm’s escape response. Results When stimulated at the head, we found that the escape response can be elicited by changes in temperature as small as a fraction of a degree Celsius, and that aspects of the escape behavior such as the response latency and the escape direction change advantageously as the amplitude of the noxious stimulus increases. We have mapped the behavioral receptive field of thermal nociception along the entire body of the worm, and show a midbody avoidance behavior distinct from the head and tail responses. At the midbody, the worm is sensitive to a change in the stimulus location as small as 80 ?m. This midbody response is probabilistic, producing either a backward, forward or pause state after the stimulus. The distribution of these states shifts from reverse-biased to forward-biased as the location of the stimulus moves from the middle towards the anterior or posterior of the worm, respectively. We identified PVD as the thermal nociceptor for the midbody response using calcium imaging, genetic ablation and laser ablation. Analyses of mutants suggest the possibility that TRPV channels and glutamate are involved in facilitating the midbody noxious response. Conclusion Through high resolution quantitative behavioral analysis, we have comprehensively characterized the C. elegans escape response to noxious thermal stimuli applied along its body, and found a novel midbody response. We further identified the nociceptor PVD as required to sense noxious heat at the midbody and can spatially differentiate localized thermal stimuli. PMID:23822173

2013-01-01

383

Mechanisms of plasticity in a Caenorhabditis elegans mechanosensory circuit  

PubMed Central

Despite having a small nervous system (302 neurons) and relatively short lifespan (14–21 days), the nematode Caenorhabditis elegans has a substantial ability to change its behavior in response to experience. The behavior discussed here is the tap withdrawal response, whereby the worm crawls backwards a brief distance in response to a non-localized mechanosensory stimulus from a tap to the side of the Petri plate within which it lives. The neural circuit that underlies this behavior is primarily made up of five sensory neurons and four pairs of interneurons. In this review we describe two classes of mechanosensory plasticity: adult learning and memory and experience dependent changes during development. As worms develop through young adult and adult stages there is a shift toward deeper habituation of response probability that is likely the result of changes in sensitivity to stimulus intensity. Adult worms show short- intermediate- and long-term habituation as well as context dependent habituation. Short-term habituation requires glutamate signaling and auto-phosphorylation of voltage-dependent potassium channels and is modulated by dopamine signaling in the mechanosensory neurons. Long-term memory (LTM) for habituation is mediated by down-regulation of expression of an AMPA-type glutamate receptor subunit. Intermediate memory involves an increase in release of an inhibitory neuropeptide. Depriving larval worms of mechanosensory stimulation early in development leads to fewer synaptic vesicles in the mechanosensory neurons and lower levels of an AMPA-type glutamate receptor subunit in the interneurons. Overall, the mechanosensory system of C. elegans shows a great deal of experience dependent plasticity both during development and as an adult. The simplest form of learning, habituation, is not so simple and is mediated and/or modulated by a number of different processes, some of which we are beginning to understand. PMID:23986713

Bozorgmehr, Tahereh; Ardiel, Evan L.; McEwan, Andrea H.; Rankin, Catharine H.

2012-01-01

384

Effects of ?-synuclein overexpression in transgenic Caenorhabditis elegans strains.  

PubMed

The neural protein ?-synuclein aggregates both in vivo and in vitro to form insoluble fibrils that are involved in Parkinson's disease pathogenesis. We have generated ?-synuclein/fluorescent-protein fusion constructs overexpressed in muscle cells of the nematode, Caenorhabdtis elegans. Green Fluorescent Protein (GFP) variants, Cerulean (C) or Venus (V), were fused to the C-terminus of human ?-synuclein (S); the resultant fusion genes were designated SV and SC, plus a CV fusion as well as S, C and V singly. The aggregation behavior of the purified fusion proteins (expressed in E. coli) will be described elsewhere. These constructs were fused to a C. elegans unc-54 myosin promoter, and integrated transgenic lines generated by microinjection, ?-irradiation, and outcrossing of fluorescent progeny. All transgenic lines expressing ?- synuclein showed significant reductions (p <0.05) in lifespan, motility and pharyngeal pumping, as compared to wildtype worms or lines expressing CFP and/or YFP only. We showed that CFP and YFP labels colocalised in granular inclusions throughout the body wall in transgenic lines expressing both SC and SV fusions (SC+SV), whereas SV+C worms displayed YFP-labelled inclusions on a diffuse CFP background. These findings implied that the ?-synuclein moieties of these fusion proteins still aggregated together in vivo, whereas CFP or YFP moieties alone did not. This in turn suggested that Foerster Resonanace Energy Transfer (FRET) between CFP and YFP labels in ?-synuclein aggregates could allow the extent of aggregation to be quantified. Accordingly, we also showed that net FRET signals increased 2- fold between L4 and adult SC+SV worms. PMID:23244416

Bodhicharla, Rakesh; Nagarajan, Archana; Winter, Jody; Adenle, Ademola; Nazir, Aamir; Brady, Declan; Vere, Kelly; Richens, Jo; O'Shea, Paul; Bell, David R; de Pomerai, David

2012-12-01

385

Effects of ?-Synuclein Overexpression in Transgenic Caenorhabditis elegans Strains  

PubMed Central

The neural protein ?-synuclein aggregates both in vivo and in vitro to form insoluble fibrils that are involved in Parkinson’s disease pathogenesis. We have generated ?-synuclein/fluorescent-protein fusion constructs overexpressed in muscle cells of the nematode, Caenorhabdtis elegans. Green Fluorescent Protein (GFP) variants, Cerulean (C) or Venus (V), were fused to the C-terminus of human ?-synuclein (S); the resultant fusion genes were designated SV and SC, plus a CV fusion as well as S, C and V singly. The aggregation behavior of the purified fusion proteins (expressed in E. coli) will be described elsewhere. These constructs were fused to a C. elegans unc-54 myosin promoter, and integrated transgenic lines generated by microinjection, ?-irradiation, and outcrossing of fluorescent progeny. All transgenic lines expressing ?-synuclein showed significant reductions (p < 0.05) in lifespan, motility and pharyngeal pumping, as compared to wild-type worms or lines expressing CFP and/or YFP only. We showed that CFP and YFP labels colocalised in granular inclusions throughout the body wall in transgenic lines expressing both SC and SV fusions (SC+SV), whereas SV+C worms displayed YFP-labelled inclusions on a diffuse CFP background. These findings implied that the ?-synuclein moieties of these fusion proteins still aggregated together in vivo, whereas CFP or YFP moieties alone did not. This in turn suggested that Foerster Resonanace Energy Transfer (FRET) between CFP and YFP labels in ?-synuclein aggregates could allow the extent of aggregation to be quantified. Accordingly, we also showed that net FRET signals increased 2-fold between L4 and adult SC+SV worms. PMID:23244416

Bodhicharla, Rakesh; Nagarajan, Archana; Winter, Jody; Adenle, Ademola; Nazir, Aamir; Brady, Declan; Vere, Kelly; Richens, Jo; O’Shea, Paul; Bell, David R; de Pomerai, David

2012-01-01

386

Transgenerational epigenetics in the germline cycle of Caenorhabditis elegans.  

PubMed

Epigenetic mechanisms create variably stable changes in gene expression through the establishment of heritable states of chromatin architecture. While many epigenetic phenomena are, by definition, heritably passed through cell division during animal and plant development, evidence suggests that 'epigenetic states' may also be inherited across multiple generations. Work in the nematode Caenorhabditis elegans has uncovered a number of mechanisms that participate in regulating the transgenerational passage of epigenetic states. These mechanisms include some that establish and maintain heritable epigenetic information in the form of histone modifications, as well as those that filter the epigenetic information that is stably transmitted. The information appears to influence and help guide or regulate gene activity and repression in subsequent generations. Genome surveillance mechanisms guided by small RNAs appear to be involved in identifying and directing heritable repression of genomic elements, and thus may participate in filtering information that is inappropriate for stable transmission. This review will attempt to summarize recent findings that illustrate this simple nematode to be a truly elegant resource for defining emerging biological paradigms.As the cell lineage that links generations, the germline is the carrier of both genetic and epigenetic information. Like genetic information, information in the epigenome can heritably affect gene regulation and phenotype; yet unlike genetic information, the epigenome of the germ lineage is highly modified within each generation. Despite such alterations, some epigenetic information is highly stable across generations, leading to transgenerationally stable phenotypes that are unlinked to genetic changes. Studies in the nematode C. elegans have uncovered mechanisms that contribute to transgenerational repression as well as to the expression of genes that rely on histone modifying machinery and/or non-coding RNA-based mechanisms. These studies indicate that epigenetic mechanisms operating within the germ cell cycle of this organism filter and maintain an epigenetic memory that is required for germ cell function and can also influence gene expression in somatic lineages. PMID:24678826

Kelly, William G

2014-01-01

387

Isoflurane Selectively Inhibits Distal Mitochondrial Complex I in Caenorhabditis Elegans  

PubMed Central

BACKGROUND Complex I of the electron transport chain (ETC) is a possible target of volatile anesthetics (VAs). Complex I enzymatic activities are inhibited by VAs, and dysfunction of complex I can lead to hypersensitivity to VAs in worms and in people. Mutant analysis in Caenorhabditis (C.) elegans suggests that VAs may specifically interfere with complex I function at the binding site for its substrate ubiquinone. We hypothesized that isoflurane inhibits electron transport by competing with ubiquinone for binding to complex I. METHODS Wildtype and mutant C. elegans were used to study the effects of isoflurane on isolated mitochondria. Enzymatic activities of the ETC were assayed and dose-response curves determined using established techniques. Two-dimensional native gels of mitochondrial proteins were performed after exposure of mitochondria to isoflurane. RESULTS Complex I is the most sensitive component of the ETC to isoflurane inhibition; however the proximal portion of complex I (the flavoprotein) is relatively insensitive to isoflurane. Isoflurane and quinone do not compete for a common binding site on complex I. The absolute rate of complex I enzymatic activity in vitro does not predict immobilization of the animal by isoflurane. Isoflurane had no measurable effect on stability of mitochondrial supercomplexes. Reduction of ubiquinone by complex I displayed positive cooperative kinetics not disrupted by isoflurane. CONCLUSIONS Isoflurane directly inhibits complex I at a site distal to the flavoprotein subcomplex. However, we have excluded our original hypothesis that isoflurane and ubiquinone compete for a common hydrophobic binding site on complex I. In addition, immobilization of the nematode by isoflurane is not due to limiting absolute amounts of complex I electron transport as measured in isolated mitochondria. PMID:21467554

Kayser, Ernst-Bernhard; Suthammarak, Wichit; Morgan, Phil G.; Sedensky, Margaret M.

2011-01-01

388

Controlling interneuron activity in Caenorhabditis elegans to evoke chemotactic behavior  

PubMed Central

Animals locate and track chemoattractive gradients in the environment to find food. With its small nervous system, Caenorhabditis elegans is a good model system1,2 in which to understand how the dynamics of neural activity control this search behavior. Extensive work on the nematode has identified the neurons that are necessary for the different locomotory behaviors underlying chemotaxis through laser ablation3–7, activity recording in immobilized animals and the study of mutants4,5. However, we do not know the neural activity patterns in C. elegans that are sufficient to control its complex chemotactic behavior. To understand how the activity in its interneurons coordinate different motor programs to lead the animal to food, we used optogenetics and new optical tools to directly manipulate neural activity in freely moving animals to evoke chemotactic behavior. By deducing the classes of activity patterns triggered during chemotaxis and exciting individual neurons with these patterns, we identified interneurons that control the essential locomotory programs for this behavior. Surprisingly, we discovered that controlling the dynamics of activity in just one interneuron pair (AIY) was sufficient to force the animal to locate, turn towards and track virtual light gradients. Two distinct activity patterns triggered in AIY as the animal moved through the gradient, controlled reversals and gradual turns to drive chemotactic behavior. Since AIY are post-synaptic to most chemosensory and thermosensory neurons8, these activity patterns in AIY are likely to play an important role in controlling and coordinating different taxis behaviors of the animal. PMID:23000898

Kocabas, Askin; Shen, Ching-Han; Guo, Zengcai V.; Ramanathan, Sharad

2012-01-01

389

The rich club of the C. elegans neuronal connectome.  

PubMed

There is increasing interest in topological analysis of brain networks as complex systems, with researchers often using neuroimaging to represent the large-scale organization of nervous systems without precise cellular resolution. Here we used graph theory to investigate the neuronal connectome of the nematode worm Caenorhabditis elegans, which is defined anatomically at a cellular scale as 2287 synaptic connections between 279 neurons. We identified a small number of highly connected neurons as a rich club (N = 11) interconnected with high efficiency and high connection distance. Rich club neurons comprise almost exclusively the interneurons of the locomotor circuits, with known functional importance for coordinated movement. The rich club neurons are connector hubs, with high betweenness centrality, and many intermodular connections to nodes in different modules. On identifying the shortest topological paths (motifs) between pairs of peripheral neurons, the motifs that are found most frequently traverse the rich club. The rich club neurons are born early in development, before visible movement of the animal and before the main phase of developmental elongation of its body. We conclude that the high wiring cost of the globally integrative rich club of neurons in the C. elegans connectome is justified by the adaptive value of coordinated movement of the animal. The economical trade-off between physical cost and behavioral value of rich club organization in a cellular connectome confirms theoretical expectations and recapitulates comparable results from human neuroimaging on much larger scale networks, suggesting that this may be a general and scale-invariant principle of brain network organization. PMID:23575836

Towlson, Emma K; Vértes, Petra E; Ahnert, Sebastian E; Schafer, William R; Bullmore, Edward T

2013-04-10

390

RNAi screening of human glycogene orthologs in the nematode Caenorhabditis elegans and the construction of the C. elegans glycogene database.  

PubMed

In this study, we selected 181 nematode glycogenes that are orthologous to human glycogenes and examined their RNAi phenotypes. The results are deposited in the Caenorhabditis elegans Glycogene Database (CGGDB) at AIST, Tsukuba, Japan. The most prominent RNAi phenotypes observed are disruptions of cell cycle progression in germline mitosis/meiosis and in early embryonic cell mitosis. Along with the previously reported roles of chondroitin proteoglycans, glycosphingolipids and GPI-anchored proteins in cell cycle progression, we show for the first time that the inhibition of the functions of N-glycan synthesis genes (cytoplasmic alg genes) resulted in abnormal germline formation, ER stress and small body size phenotypes. The results provide additional information on the roles of glycoconjugates in the cell cycle progression mechanisms of germline and embryonic cells. PMID:25091817

Akiyoshi, Sayaka; Nomura, Kazuko H; Dejima, Katsufumi; Murata, Daisuke; Matsuda, Ayako; Kanaki, Nanako; Takaki, Tetsuro; Mihara, Hiroyuki; Nagaishi, Takayuki; Furukawa, Shuhei; Ando, Keiko-Gengyo; Yoshina, Sawako; Mitani, Shohei; Togayachi, Akira; Suzuki, Yoshinori; Shikanai, Toshihide; Narimatsu, Hisashi; Nomura, Kazuya

2015-01-01

391

Cyp35a2 gene expression is involved in toxicity of fenitrothion in the soil nematode Caenorhabditis elegans.  

PubMed

In this study, the effect of organophosphorous (OP) pesticide, fenitrothion (FT), on the non-target organism was investigated using the soil nematode, Caenorhabditis elegans. Toxicity was investigated on multiple biological levels, from organism to molecular levels, such as, immoblity, growth, fertility, development, acetyl cholinesterase (AChE) activity and stress-response gene expressions. FT may provoke serious consequences on the C. elegans population, as it induced significant developmental disturbance. As expected, FT exposure inhibits AChE activity of C. elegans. The increased expression of the cytochrome p450 family protein 35A2 (cyp35a2) gene was also observed in FT exposed worms. To experimentally demonstrate the relationships between organism-level effects and the cyp35a2 gene expression in FT-exposed C. elegans, the integration of the gene expression with biochemical-, and organism level endpoints were attempted using a C. elegans cyp35a2 RNA interference (RNAi) and cyp35a2 mutant (gk317). The 24 h-EC50s of C. elegans on FT exposure were in the order of cyp35a2 RNAi in cyp35a2 mutant (gk317)>cyp35a2 mutant (gk317)>cyp35a2 RNAi in wildtype (N2)>wildtype (N2). The higher EC50 values of cyp35a2 RNAi and cyp35a2 mutant (gk317) compared to that of wildtype C. elegans strongly supported that cyp35a2 gene plays an important role in the toxicity of FT towards C. elegans. The experiments with cyp35a2 RNAi also indicated that the development disturbance and decreased AChE activity, which were observed in FT exposed wildtype C. elegans were significantly rescued in the cyp35a2 RNAi C. elegans. Overall results suggest that the cyp35a2 may be an important gene for exerting FT toxicity in C. elegans. PMID:21658740

Roh, Ji-Yeon; Choi, Jinhee

2011-09-01

392

Ectopic expression of a Haemonchus contortus GATA transcription factor in Caenorhabditis elegans reveals conserved function in spite of extensive sequence divergence  

Microsoft Academic Search

Comparative analysis between Caenorhabditis elegans and other nematode species offers a powerful approach to study gene function. C. elegans also has great potential as a surrogate expression system to study the function of genes from parasitic nematode species where transgenic methodologies are unavailable. However there is little information on the extent to which the biology of C. elegans is conserved

Annabelle Couthier; Judith Smith; Pamela McGarr; Barbara Craig; John S Gilleard

2004-01-01

393

Var gene transcription and clinical disease manifestation in African P. falciparum malaria field isolates   

E-print Network

The Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) variant surface antigens, encoded by the var gene family, play a crucial role in malaria pathogenesis through mediating immunomodulation and host cell ...

Kyriacou, Helen M

2008-01-01

394

Molecular Cloning and Characterization of the Insecticidal Crystal Protein Gene of Bacillus thuringiensis Var. Tenebrionis  

Microsoft Academic Search

The insecticidal crystal protein gene of the coleopteran-toxic Bacillus thuringiensis var. tenebrionis has been isolated, and the nucleotide sequence has been determined. A total DNA library from var. tenebrionis was made in the plasmid vector pUC12. By using a synthetic 27-base oligonucleotide corresponding to a stretch of nine N-terminal amino acids of a tryptic fragment of purified crystal protein of

Vaithilingam Sekar; David V. Thompson; Michael J. Maroney; Roger G. Bookland; Michael J. Adang

1987-01-01

395

Allelopathy on Bark of Downed Logs of Chamaecyparis Obtusa sieb. and Zucc. var. formosana (Hayata) Rehder  

Microsoft Academic Search

Chamaecyparis obtusa Sieb. and Zucc. var. formosana (Hayata) Rehder is the dominant species in the temperate forest of Yuanyang Lake Nature Reserve (YYL), Taiwan. Although downed\\u000a logs of C. obstusa var. formosana occupy only a small percentage of the forest floor area in YYL, they are important regeneration substrates. Seedlings of\\u000a this species often grow without competition on the new

Mei-Hwei Tseng; Wen-Rong Lai; Chin-Lin Hsieh; Yueh-Hsiung Kuo

2007-01-01

396

Analysis of Genetic Diversity and Population Differentiation of Larix potaninii var . chinensis Using Microsatellite DNA  

Microsoft Academic Search

\\u000a Larix potaninii var. chinensis is endemic to China and is found only on several peaks of the Qinling Mountains in Shaanxi Province. In China, it is classified\\u000a in the second class of national protected rare plants. To estimate genetic diversity and to analyze population genetic structure\\u000a of L. potaninii var. chinensis, 120 individual samples from six natural populations were assessed

Xiao-Min Yu; Qing Zhou; Zeng-Qiang Qian; Shan Li; Gui-Fang Zhao

2006-01-01

397

Analysis of genetic diversity in Agave tequilana var. Azul using RAPD markers  

Microsoft Academic Search

By federal law in Mexico, A. tequilana Weber var. Azul is the only variety of agave permitted for the production of any tequila. Our objective was to assay levels\\u000a of genetic variation in field populations of A. tequilana var. Azul using randomly amplified polymorphic DNA (RAPD) markers. Ten plants were collected from each of four different\\u000a fields, with two fields

Katia Gil Vega; Mario González Chavira; Octavio Martínez de la Vega; June Simpson; George Vandemark

2001-01-01

398

Monotropastrum humile var. humile is associated with diverse ectomycorrhizal Russulaceae fungi in Japanese forests  

Microsoft Academic Search

Monotropastrum humile is nearly lacking in chlorophyll and obtains its nutrients, including carbon sources, from associated mycorrhizal fungi.\\u000a We analyzed the mycorrhizal fungal affinity and species diversity of M. humile var. humile mycorrhizae to clarify how the plant population survives in Japanese forest ecosystems. We classified 78 samples of adult\\u000a M. humile var. humile individuals from Hokkaido, Honshu, and Kyusyu

Akiyoshi Yamada; Daisei Kitamura; Masanobu Setoguchi; Yosuke Matsuda; Yasushi Hashimoto; Norihisa Matsushita; Masaki Fukuda

2008-01-01

399

Taxonomic status of Monotropastrum   humile , with special reference to M.   humile var. glaberrimum (Ericaceae, Monotropoideae)  

Microsoft Academic Search

Taxonomic treatment of the achlorophyllous monotropoid plant Monotropastrum humile is still unclear and confusing because of the lack of detailed morphological analyses and molecular phylogeny. In particular,\\u000a the taxonomic status of a glabrous variety, M. humile var. glaberrimum, is under debate. Our detailed examination of the morphological characteristics of living plants revealed that M. humile var. glaberrimum can be easily distinguished from the

Hirokazu Tsukaya; Jun Yokoyama; Ryoko Imaichi; Hideaki Ohba

2008-01-01

400

Valeur alimentaire de rgimes base de cactus inerme (Opunfia ficus indica var. Inermis) et  

E-print Network

Valeur alimentaire de régimes à base de cactus inerme (Opunfia ficus indica var. Inermis) et d régimes à base de cactus inerme (Opuntia ficus indica, var. Inermis) et d'Atriplex nummularia. Quinze aléatoire en trois lots de cinq têtes chacun. Chaque lot a reçu un régime composé d'atriplex et de cactus en

Paris-Sud XI, Université de

401

Fatty acids of canola Brassica campestris var candle seed and oils at various stages of refining  

Microsoft Academic Search

Fatty acids of oil of a current variety of canolaBrassica campestris var Candle, at 3 stages of commercial production and refining, were compared with authentic seed oils, and with the oil ofB. napus var Tower. The proportion ofcis- 9, cis- 12, trans- 15 andtrans- 9, cis-12, cis-lS-octadecatrienoates relative to the all-cis isomer was lower than that previously observed in processed

J. L. Sebedio; R. G. Ackman

1981-01-01

402

Characterization of the antigenicity of Cpl1, a surface protein of Cryptococcus neoformans var. neoformans.  

PubMed

Cryptococcus neoformans var. neoformans is an important fungal pathogen. The capsule is a well established virulence factor and a target site for diagnostic tests. The CPL1 gene is required for capsular formation and virulence. The protein product Cpl1 has been proposed to be a secreted protein, but the characteristics of this protein have not been reported. Here we sought to characterize Cpl1. Phylogenetic analysis showed that the Cpl1 of C. neoformans var. neoformans and the Cpl1 orthologs identified in C. neoformans var. grubii and C. gattii formed a distinct cluster among related fungi; while the putative ortholog found in Trichosporon asahii was distantly related to the Cryptococcus cluster. We expressed Cpl1 abundantly as a secreted His-tagged protein in Pichia pastoris. The protein was used to immunize guinea pigs and rabbits for high titer mono-specific polyclonal antibody that was shown to be highly specific against the cell wall of C. neoformans var. neoformans and did not cross react with C. gattii, T. asahii, Aspergillus spp., Candida spp. and Penicillium spp. Using the anti-Cpl1 antibody, we detected Cpl1 protein in the fresh culture supernatant of C. neoformans var. neoformans and we showed by immunostaining that the Cpl1 protein was located on the surface. The Cpl1 protein is a specific surface protein of C. neoformans var. neoformans. PMID:25261494

Cai, Jian-Piao; Liu, Ling-Li; To, Kelvin K W; Lau, Candy C Y; Woo, Patrick C Y; Lau, Susanna K P; Guo, Yong-Hui; Ngan, Antonio H Y; Che, Xiao-Yan; Yuen, Kwok-Yung

2015-01-01

403

Penetration, Post-penetration Development, and Reproduction of Meloidogyne incognita on Cucumis melo var. texanus.  

PubMed

Cucumis melo var. texanus, a wild melon commonly found in the southern United States and two accessions, Burleson Co. and MX 1230, expressed resistance to Meloidogyne incognita in preliminary experiments. To characterize the mechanism of resistance, we evaluated root penetration, post-penetration development, reproduction, and emigration of M. incognita on these two accessions of C. melo var. texanus. Additionally, we evaluated 22 accessions of C. melo var. texanus for their reaction against M. incognita in a greenhouse experiment. Fewer (P ? 0.05) J2 penetrated the root system of C. melo var. texanus accessions (Burleson Co. and MX 1230) and C. metuliferus (PI 482452) (resistant control), 7 days after inoculation (DAI) than in C. melo 'Hales Best Jumbo' (susceptible control). A delayed (P ? 0.05) rate of nematode development was observed at 7, 14, and 21 DAI that contributed to lower (P ? 0.05) egg production on both accessions and C. metuliferus compared with C. melo. Though J2 emigration was observed on all Cucumis genotypes a higher (P ? 0.05) rate of J2 emigration was observed from 3 to 6 DAI on accession Burleson Co. and C. metuliferus than on C. melo. The 22 accessions of C. melo var. texanus varied relative to their reaction to M. incognita with eight supporting similar levels of nematode reproduction to that of C. metuliferus. Cucumis melo var. texanus may be a useful source of resistance against root-knot nematode in melon. PMID:23589661

Faske, T R

2013-03-01

404

Copyright 2003 by the Genetics Society of America DIM-1, a Novel Immunoglobulin Superfamily Protein in Caenorhabditis elegans,  

E-print Network

initial muscle assembly in C. elegans to form dense bodies and M-lines. Loss of this protein results in viable animals that have disorganized bodywall muscle and are paralyzed as adults. Loss or reduction Protein in Caenorhabditis elegans, Is Necessary for Maintaining Bodywall Muscle Integrity Teresa M

Moerman, Donald G.

405

Wnt and EGF pathways act together to induce C. elegans male hook development Hui Yu a,1,2  

E-print Network

Wnt and EGF pathways act together to induce C. elegans male hook development Hui Yu a,1,2 , Adeline on the evolution of patterning networks, we studied the C. elegans male hook competence group (HCG), an equivalence of the EGF pathway decreases dependence on LIN-17 and causes ectopic hook development. Our results suggest

Horvitz, H. Robert

406

Reversal Frequency in Caenorhabditis elegans Represents an Integrated Response to the State of the Animal and Its Environment  

Microsoft Academic Search

The locomotion of Caenorhabditis elegans consists of forward crawling punctuated by spontaneous reversals. To better understand the important variables that affect locomotion, we have described in detail the locomotory behavior of C. elegans and identified a set of parameters that are sufficient to describe the animal's trajectory. A model of locomotion based on these parameters indicates that reversal frequency plays

Beibei Zhao; Parul Khare; Lisa Feldman; Joseph A. Dent

2003-01-01

407

C. elegans HLH-2/E/Daughterless controls key regulatory cells during gonadogenesis Michael A. Chesney a  

E-print Network

C. elegans HLH-2/E/Daughterless controls key regulatory cells during gonadogenesis Michael A April 2009 Keywords: HLH-2, lag-2, Distal tip cell Stem cell niche Morphogenesis Leader function. elegans homolog of E/ Daughterless, HLH-2, was previously implicated in hDTC specification. Here we report

Kimble, Judith

408

A comparative metabolomic study of NHR-49 in Caenorhabditis elegans and PPAR-a in the mouse  

E-print Network

with multivariate statistics to examine the metabolic changes in Caenorhabditis elegans fol- lowing the deletion involved in human disease, including those involved in diabetes and obesity, have homologues in C. elegans. These tools have been used in conjunction with multivariate statistics to exam- ine the role of nhr-49. Whilst

Miska, Eric

409

A test of life-history theories of immune defence in two ecotypes of the garter snake, Thamnophis elegans  

E-print Network

immunity in replicate populations of two life- history ecotypes of the garter snake Thamnophis elegans, oneA test of life-history theories of immune defence in two ecotypes of the garter snake, Thamnophis elegans Amanda Marie Sparkman* and Maria Gabriela Palacios Department of Ecology, Evolution & Organismal

Bronikowski, Anne

410

Adaptive divergence within and between ecotypes of the terrestrial garter snake, Thamnophis elegans , assessed with F ST - Q ST comparisons  

Microsoft Academic Search

Populations of the terrestrial garter snake (Thamnophis elegans) around Eagle Lake in California exhibit dramatic ecotypic differentiation in life history, colouration and morphology across distances as small as a few kilometres. We assayed the role of selection in ecotypic differentiation in T. elegans using FST- QST analysis and identified selective agents using direct and indirect observa- tions. We extended the

M. K. MANIER; C. M. SEYLER; S. J. ARNOLD

2007-01-01

411

C. elegans pgp-5 IS INVOLVED IN RESISTANCE TO BACTERIAL INFECTION AND HEAVY METAL AND ITS REGULATION  

E-print Network

C. elegans pgp-5 IS INVOLVED IN RESISTANCE TO BACTERIAL INFECTION AND HEAVY METAL AND ITS of a C. elegans ABC transporter, pgp-5 is induced by both bacterial infection and heavy metal stress contributes to resistance to bacterial infection and heavy metals. Using pgp-5 transcription as a read-out, we

Baillie, David

412

Identification of a gonadotropin-releasing hormone receptor orthologue in Caenorhabditis elegans  

PubMed Central

Background The Caenorhabditis elegans genome is known to code for at least 1149 G protein-coupled receptors (GPCRs), but the GPCR(s) critical to the regulation of reproduction in this nematode are not yet known. This study examined whether GPCRs orthologous to human gonadotropin-releasing hormone receptor (GnRHR) exist in C. elegans. Results Our sequence analyses indicated the presence of two proteins in C. elegans, one of 401 amino acids [GenBank: NP_491453; WormBase: F54D7.3] and another of 379 amino acids [GenBank: NP_506566; WormBase: C15H11.2] with 46.9% and 44.7% nucleotide similarity to human GnRHR1 and GnRHR2, respectively. Like human GnRHR1, structural analysis of the C. elegans GnRHR1 orthologue (Ce-GnRHR) predicted a rhodopsin family member with 7 transmembrane domains, G protein coupling sites and phosphorylation sites for protein kinase C. Of the functionally important amino acids in human GnRHR1, 56% were conserved in the C. elegans orthologue. Ce-GnRHR was actively transcribed in adult worms and immunoanalyses using antibodies generated against both human and C. elegans GnRHR indicated the presence of a 46-kDa protein, the calculated molecular mass of the immature Ce-GnRHR. Ce-GnRHR staining was specifically localized to the germline, intestine and pharynx. In the germline and intestine, Ce-GnRHR was localized specifically to nuclei as revealed by colocalization with a DNA nuclear stain. However in the pharynx, Ce-GnRHR was localized to the myofilament lattice of the pharyngeal musculature, suggesting a functional role for Ce-GnRHR signaling in the coupling of food intake with reproduction. Phylogenetic analyses support an early evolutionary origin of GnRH-like receptors, as evidenced by the hypothesized grouping of Ce-GnRHR, vertebrate GnRHRs, a molluscan GnRHR, and the adipokinetic hormone receptors (AKHRs) and corazonin receptors of arthropods. Conclusion This is the first report of a GnRHR orthologue in C. elegans, which shares significant similarity with insect AKHRs. In vertebrates, GnRHRs are central components of the reproductive endocrine system, and the identification of a GnRHR orthologue in C. elegans suggests the potential use of C. elegans as a model system to study reproductive endocrinology. PMID:17134503

Vadakkadath Meethal, Sivan; Gallego, Miguel J; Haasl, Ryan J; Petras, Stephen J; Sgro, Jean-Yves; Atwood, Craig S

2006-01-01

413

Study about locomotory ability of dystrophin-defected C.elegans after spaceflight  

NASA Astrophysics Data System (ADS)

Space microgravity could induce a variety of biological changes such as muscular atrophy. Recent studies show that gravisensing is a key point in muscular atrophy process, but the molecular mechanism is still unknown. Dystrophin, a muscle-related protein, plays an important role in muscle development. It is reported that mutation of human dystrophin gene could cause muscular atrophy. In this study, we focus on whether dystrophin gene acts as a gravisensing factor and observe locomotory ability of dystrophin-defected Caenorhabditis elegans (C.elegans) after spaceflight. We used wild-type (WT) and dystrophin-defected (dys-1) mutant of C.elegans, which were cultured to dauer stage and sent to space by Shenzhou 8 spacecraft (from Nov 1st to 17th, 2011). These worms were divided into three groups: space group (space radiation and microgravity conditions), space control group (space radiation and chmetcnvTCSC0NumberType1NegativeFalseHasSpaceFalseSourceValue1UnitNameg1g centrifuge force conditions) and ground control group.We already observed the progeny (generation F1 and F2) of worms which were sent to space, the movement of C. elegans is restricted to a two-dimensional sinusoidal pattern, and evaluated locomotory ability by the ratio (length/width) in crawl trace wave of C. elegans. The increased value of ratio indicates the decrease in locomotory ability of C. elegans. Our results from generation F1 showed that WT worms in space group(7.7±1.8) demonstrated the significant decrease in locomotory ability about 15%, compared with those in space control group(6.7±1.2). This finding indicates that locomotory ability of C. elegans progeny could be affected by microgravity in space environment. In comparison to the obvious difference in ratio between space group and space control group for WT worms, there is no significant difference between two space groups of generation F2 .For dys-1 mutant of C.elegans (generation F1 and F2), the results show that dystrophin deficiency results in no response to microgravity, compared with WT, suggesting that dys-1 gene plays a role in locomotory ability under ground gravity. Further, we performed all genome microarray analysis and found that expression of several muscle-related genes in dys-1 mutant groups were also changed, accompanied with changes in biological processes such as oxidation, protein modification and metabolic process. Our findings suggest that dystrophin gene could act as a gravisensing and affect locomotory ability of C. elegans progeny.

Gao, Ying; Sun, Yeqing; Lei, Huang; Xu, Dan

2012-07-01

414

The Caenorhabditis elegans Gene mfap-1 Encodes a Nuclear Protein That Affects Alternative Splicing  

PubMed Central

RNA splicing is a major regulatory mechanism for controlling eukaryotic gene expression. By generating various splice isoforms from a single pre–mRNA, alternative splicing plays a key role in promoting the evolving complexity of metazoans. Numerous splicing factors have been identified. However, the in vivo functions of many splicing factors remain to be understood. In vivo studies are essential for understanding the molecular mechanisms of RNA splicing and the biology of numerous RNA splicing-related diseases. We previously isolated a Caenorhabditis elegans mutant defective in an essential gene from a genetic screen for suppressors of the rubberband Unc phenotype of unc-93(e1500) animals. This mutant contains missense mutations in two adjacent codons of the C. elegans microfibrillar-associated protein 1 gene mfap-1. mfap-1(n4564 n5214) suppresses the Unc phenotypes of different rubberband Unc mutants in a pattern similar to that of mutations in the splicing factor genes uaf-1 (the C. elegans U2AF large subunit gene) and sfa-1 (the C. elegans SF1/BBP gene). We used the endogenous gene tos-1 as a reporter for splicing and detected increased intron 1 retention and exon 3 skipping of tos-1 transcripts in mfap-1(n4564 n5214) animals. Using a yeast two-hybrid screen, we isolated splicing factors as potential MFAP-1 interactors. Our studies indicate that C. elegans mfap-1 encodes a splicing factor that can affect alternative splicing. PMID:22829783

Ma, Long; Gao, Xiaoyang; Luo, Jintao; Huang, Liange; Teng, Yanling; Horvitz, H. Robert

2012-01-01

415

Modeling Molecular and Cellular Aspects of Human Disease using the Nematode Caenorhabditis elegans  

PubMed Central

As an experimental system, Caenorhabditis elegans, offers a unique opportunity to interrogate in vivo the genetic and molecular functions of human disease-related genes. For example, C. elegans has provided crucial insights into fundamental biological processes such as cell death and cell fate determinations, as well as pathological processes such as neurodegeneration and microbial susceptibility. The C. elegans model has several distinct advantages including a completely sequenced genome that shares extensive homology with that of mammals, ease of cultivation and storage, a relatively short lifespan and techniques for generating null and transgenic animals. However, the ability to conduct unbiased forward and reverse genetic screens in C. elegans remains one of the most powerful experimental paradigms for discovering the biochemical pathways underlying human disease phenotypes. The identification of these pathways leads to a better understanding of the molecular interactions that perturb cellular physiology, and forms the foundation for designing mechanism-based therapies. To this end, the ability to process large numbers of isogenic animals through automated work stations suggests that C. elegans, manifesting different aspects of human disease phenotypes, will become the platform of choice for in vivo drug discovery and target validation using high-throughput/content screening technologies. PMID:18852689

Silverman, Gary A.; Luke, Cliff J.; Bhatia, Sangeeta R.; Long, Olivia S.; Vetica, Anne C.; Perlmutter, David H.; Pak, Stephen C.

2009-01-01

416

Splicing of a C. elegans myosin pre-mRNA in a human nuclear extract.  

PubMed

Splicing of mammalian introns requires that the intron possess at least 80 nucleotides. This length requirement presumably reflects the constraints of accommodating multiple snRNPs simultaneously in the same intron. In the free-living nematode, C. elegans, introns typically are 45 to 55 nucleotides in length. In this report, we determine whether C. elegans introns can obviate the mammalian length requirement by virtue of their structure or sequence. We demonstrate that a 53 nucleotide intron from the unc-54 gene of C. elegans does not undergo splicing in a mammalian (HeLa) nuclear extract. However, insertion of 31 nucleotides of foreign, prokaryotic sequence into the same intron results in efficient splicing. The observed splicing proceeds by the same two-step mechanism observed with mammalian introns, and exploits the same 3' and 5' splice sites as are used in C. elegans. The branch point used lies in the inserted sequence. We conclude that C. elegans splicing components are either fewer in number or smaller than their mammalian counterparts. PMID:2308820

Ogg, S C; Anderson, P; Wickens, M P

1990-01-11

417

Extension of Lifespan in C. elegans by Naphthoquinones That Act through Stress Hormesis Mechanisms  

PubMed Central

Hormesis occurs when a low level stress elicits adaptive beneficial responses that protect against subsequent exposure to severe stress. Recent findings suggest that mild oxidative and thermal stress can extend lifespan by hormetic mechanisms. Here we show that the botanical pesticide plumbagin, while toxic to C. elegans nematodes at high doses, extends lifespan at low doses. Because plumbagin is a naphthoquinone that can generate free radicals in vivo, we investigated whether it extends lifespan by activating an adaptive cellular stress response pathway. The C. elegans cap‘n’collar (CNC) transcription factor, SKN-1, mediates protective responses to oxidative stress. Genetic analysis showed that skn-1 activity is required for lifespan extension by low-dose plumbagin in C. elegans. Further screening of a series of plumbagin analogs identified three additional naphthoquinones that could induce SKN-1 targets in C. elegans. Naphthazarin showed skn-1dependent lifespan extension, over an extended dose range compared to plumbagin, while the other naphthoquinones, oxoline and menadione, had differing effects on C. elegans survival and failed to activate ARE reporter expression in cultured mammalian cells. Our findings reveal the potential for low doses of naturally occurring naphthoquinones to extend lifespan by engaging a specific adaptive cellular stress response pathway. PMID:21765926

Wilson, Mark A.; Yu, Quian-Sheng; Wood, William H.; Zhang, Yongqing; Becker, Kevin G.; Greig, Nigel H.; Mattson, Mark P.; Camandola, Simonetta; Wolkow, Catherine A.

2011-01-01

418

hunchback and Ikaros-like zinc finger genes control reproductive system development in Caenorhabditis elegans.  

PubMed

Here we provide evidence for a C2H2 zinc finger gene family with similarity to Ikaros and hunchback. The founding member of this family is Caenorhabditis elegans ehn-3, which has important and poorly understood functions in somatic gonad development. We examined the expression and function of four additional hunchback/Ikaros-like (HIL) genes in C. elegans reproductive system development. Two genes, ehn-3 and R08E3.4, are expressed in somatic gonadal precursors (SGPs) and have overlapping functions in their development. In ehn-3; R08E3.4 double mutants, we find defects in the generation of distal tip cells, anchor cells, and spermatheca; three of the five tissues derived from the SGPs. We provide in vivo evidence that C. elegans HIL proteins have functionally distinct zinc finger domains, with specificity residing in the N-terminal set of four zinc fingers and a likely protein-protein interaction domain provided by the C-terminal pair of zinc fingers. In addition, we find that a chimeric human Ikaros protein containing the N-terminal zinc fingers of EHN-3 functions in C. elegans. Together, these results lend support to the idea that the C. elegans HIL genes and Ikaros have similar functional domains. We propose that hunchback, Ikaros, and the HIL genes arose from a common ancestor that was present prior to the divergence of protostomes and deuterostomes. PMID:20026024

Large, Edward E; Mathies, Laura D

2010-03-01

419

Cytoplasmic expression of mouse prion protein causes severe toxicity in Caenorhabditis elegans.  

PubMed

To test if Caenorhabditis elegans could be established as a model organism for prion study, we created transgenic C. elegans expressing the cytosolic form of the mouse prion protein, MoPrP(23-231), which lacks the N-terminal signal sequence and the C-terminal glycosylphosphatidylinisotol (GPI) anchor site. We report here that transgenic worms expressing MoPrP(23-231)-CFP exhibited a wide range of distinct phenotypes: from normal growth and development, reduced mobility and development delay, complete paralysis and development arrest, to embryonic lethality. Similar levels of MoPrP(23-231)-CFP were produced in animals exhibiting these distinct phenotypes, suggesting that MoPrP(23-231)-CFP might have misfolded into distinct toxic species. In combining with the observation that mutations in PrP that affect prion pathogenesis also affect the toxic phenotypes in C. elegans, we conclude that the prion protein-folding mechanism is similar in mammals and C. elegans. Thus, C. elegans can be a useful model organism for prion research. PMID:18519028

Park, Kyung-Won; Li, Liming

2008-08-01

420

A microfluidic device and automatic counting system for the study of C. elegans reproductive aging.  

PubMed

The nematode Caenorhabditis elegans (C. elegans) is an excellent model to study reproductive aging because of its short life span, its cessation of reproduction in mid-adulthood, and the strong conservation of pathways that regulate longevity. During its lifetime, a wild-type C. elegans hermaphrodite usually lays about 200-300 self-fertilized hatchable eggs, which mainly occurs in the first three to five days of adulthood. Here, we report the development of a microfluidic assay and a real-time, automatic progeny counting system that records progeny counting information from many individual C. elegans hermaphrodites. This system offers many advantages compared to conventional plate assays. The flow of non-proliferating bacteria not only feeds the worms but also flushes the just-hatched young progeny through a filter that separates mothers from their offspring. The progeny that are flushed out of the chamber are detected and recorded using a novel algorithm. In our current design, one device contains as many as 16 individual chambers. Here we show examples of real-time progeny production information from wild-type (N2) and daf-2 (insulin receptor) mutants. We believe that this system has the potential to become a powerful, high time-resolution tool to study the detailed reproduction of C. elegans. PMID:25407755

Li, Siran; Stone, Howard A; Murphy, Coleen T

2015-01-21

421

Eremophilane-type sesquiterpene derivatives from Senecio aegyptius var. discoideus.  

PubMed

Investigation of a CH(2)Cl(2) extract of the aerial parts of Senecio aegyptius var. discoideus afforded nine eremophilane compounds, of which six are new (1-6), namely, 1beta-hydroxy-8alphaH-eremophil-7(11),9-dien-8beta,12-olide (1), 1beta,8alpha-dihydroxyeremophil-7(11),9-dien-8beta,12-olide (2), 1beta-hydroxy-8alpha-methoxyeremophil-7(11),9-dien-8beta,12-olide (3), 1-oxo-8alpha-methoxy-10alphaH-eremophil-7(11)-en-8beta,12-lactam (4), 1beta,10beta-epoxy-8alpha-hydroxyeremophil-7(11)-en-8beta,12-olide (5), and 1beta,10beta-epoxy-8alpha-methoxyeremophil-7(11)-en-8beta,12-olide (6). The structures of 1-6 were elucidated by spectroscopic methods and by comparison with literature data. The antibacterial activity of the isolated compounds was tested against Bacillus cereus and a Serratia sp. PMID:15787455

El-Hamd H Mohamed, Abou; Ahmed, Ahmed A

2005-03-01

422

Transport of Bacillus Thuringiensis var. Kurstaki Via Fomites  

PubMed Central

The intentional and controlled release of an aerosolized bacterium provides an opportunity to investigate the implications of a biological attack. Since 2006, Los Alamos National Laboratory has worked with several urban areas, including Fairfax County, VA, to design experiments to evaluate biodefense concepts of operations using routine spraying of Bacillus thuringiensis var. kurstaki (Btk). Btk is dispersed in large quantities as a slurry to control the gypsy moth, Lymantria dispar. Understanding whether personnel and equipment pick up residual contamination during sampling activities and transport it to other areas is critical for the formulation of appropriate response and recovery plans. While there is a growing body of literature surrounding the transmission of viral diseases via fomites, there is limited information on the transport of Bacillus species via this route. In 2008, LANL investigated whether field sampling activities conducted near sprayed areas, post-spray, resulted in measurable cross-contamination of sampling personnel, equipment, vehicles, and hotel rooms. Viable Btk was detected in all sample types, indicating transport of the agent occurred via fomites. PMID:21882970

Van Cuyk, Sheila; Veal, Lee Ann B.; Simpson, Beverley

2011-01-01

423

Micropropagation of globe artichoke (Cynara cardunculus L. var. scolymus).  

PubMed

The globe artichoke (Cynara cardunculus L. var. scolymus) is a perennial plant cultivated in the Mediterranean region and the Americas for its edible young flower heads. Although vegetative propagation by offshoots or by "ovoli" (underground dormant axillary buds) has been the primary method of propagation, the potential for the diffusion of diseases and the phenotypic variability can be very high. The propagation of this species by axillary shoot proliferation from in vitro-cultured meristems produces systemic pathogen-free plants and a higher multiplication rate as compared to that obtained by conventional agamic multiplication. Axillary shoot proliferation can be induced from excised shoot apices cultured on Murashige and Skoog agar solidified medium supplemented with various concentrations of cytokinins and auxins, depending on genotype. For the production of virus-free plants, meristems, 0.3-0.8 mm long are excised from shoot apices and surface sterilized. The transfer of artichoke microshoots to a medium lacking cytokinins or with low cytokinin concentration is critical for rooting. Adventitious roots develop within 3-5 weeks after transfer to root induction MS medium containing NAA or IAA at various concentrations. However, in vitro rooting frequency rate is dependent on the genotype and the protocol used. Acclimatization of in vitro microshoots having 3-4 roots is successfully accomplished; plantlets develop new roots in ex vitro conditions and continue to grow. PMID:23179714

Iapichino, Giovanni

2013-01-01

424

A study of the anther size and its relation to certain other characters of the spikelets in a cross between Avena sativa L. var. Bronco and Avena sterilis L. var. Macrocarpa  

E-print Network

A STUDY OF THE ANTHER SIZE AND ITS RELATION TO CERTAIN OTHER CHARACTERS OF THE SPIKELETS IN A CROSS BEIWEEN AVENA SATIVA L. VAR. BRONCO AND AVENA STERILIS L. VAR. MACROCARPA A Thesis By Heung Bae Kim Submitted to the Graduate College... AVENA SATIVA L. VAR. BRONCO AND AVENA STERILIS L. VAR. MACROCARPA A Thesis By Heung Bae Kim Approved as to style and content by: (Chai. rman of Committee) r (Member) ( ead of Department) (Me ber) May 1966 ACKNCMLEDGMENTS The writer is highly...

Kim, Heung Bae

1966-01-01

425

Effect of intercropping Panicum maximum var. Ntchisi and Lablab purpureus on the growth, herbage yield and chemical composition of Panicum maximum var. Ntchisi at different harvesting times.  

PubMed

The study was conducted to evaluate the effect of intercropping Panicum maximum var. Ntchisi and Lablab purpureus on the growth, herbage yield and chemical composition of P. maximum var. Ntchisi at different harvesting times at the Teaching and Research farm, Federal University of Agriculture, Abeokuta in a randomized complete block design. Samples were collected at different harvesting times (8, 10, 12, 14 weeks after planting). The growth parameters which were plant height, leaf length, leaf number and tiller number measured showed that the intercropping of grass with legume were higher than in the sole plot of P. maximum var. Ntchisi. The plant yield was consistently higher (p < 0.05) in intercropped forages than in sole throughout the harvesting times. The crude protein contents of the forages were also higher for the intercropped across the treatments. The values of the fibre components were significantly different (p < 0.05) at different harvesting times and it was increasing as the harvesting time was increasing. From this study, considering the herbage yield and chemical composition of intecropping Panicum maximum var. Ntchisi and Lablab purpureus, they can be grazed by ruminant animals or harvested at 12 weeks after planting when the quality and quantity will support livestock productivity and can be conserved to be fed to ruminant animals during dry season when feed availability and quality are extremely low. PMID:24511710

Ojo, V O A; Dele, P A; Amole, T A; Anele, U Y; Adeoye, S A; Hassan, O A; Olanite, J A; Idowu, O J

2013-11-15

426

Genetic Linkage Map of Citrullus lanatus var. Citroides Chromosomal Segments Introgressed into the Watermelon Cultivar Crimson Sweet (Citrullus lanatus var. lanatus) Genome  

Technology Transfer Automated Retrieval System (TEKTRAN)

There is need to develop of introgression lines, useful for genetic studies and genetic enhancement of watermelon. In this study, we used an advanced recombinant population (BC2F2) to identify and map chromosomal segments of the wild watermelon Citrullus lanatus var. citroides that were incorporate...

427

Insights into the functions of the Death Associated Protein Kinases from C. elegans and other invertebrates  

PubMed Central

The death associated protein kinases (DAPK) are a phylogenetically widespread family of calcium-regulated serine/threonine kinases, initially identified from their roles in apoptosis. Subsequent studies, principally in vertebrate cells or models, have elucidated the functions of the DAPK family in autophagy and tumor suppression. Invertebrate genetic model organisms such as Drosophila and C. elegans have revealed additional functions for DAPK and related kinases. In the nematode C. elegans, the sole DAPK family member DAPK-1 positively regulates starvation-induced autophagy. Genetic analysis in C. elegans has revealed that DAPK-1 also acts as a negative regulator of epithelial innate immune responses in the epidermis. This negative regulatory role for DAPK in innate immunity may be analogous to the roles of mammalian DAPK in inflammatory responses. PMID:24242918

Chuang, Marian; Chisholm, Andrew D.

2013-01-01

428

Reference toxicants for toxicity testing using Caenorhabditis elegans in aquatic media  

SciTech Connect

Caenorhabditis elegans aquatic toxicity assays were standardized with five common reference toxicants: CdCl{sub 2}, NaCl, KCl, sodium lauryl sulfate (SLS), and sodium pentachlorophenate (PCP). Aquatic toxicity testing was conducted in 3 media: a standard C. elegans medium; EPA moderately hard reconstituted water; and EPA moderately hard mineral water. Test duration in each medium was 24h without a food source, and 24h and 48h with Escherichia coli strain OP50 as a food source. Each test was replicated three times with each replicate having 6 wells per concentration, 10 worms per well. LC{sub 50} values were calculated using probit analysis. The average LC{sub 50}s for each set of replications were compared to assess sensitivity and reproducibility of the data, identifying expected variation between replicate tests. These reference toxicants increase the database for C. elegans and provide a benchmark for further application.

Cressman, C.P. III; Williams, P.L. [Univ. of Georgia, Athens, GA (United States)

1997-09-01

429

Pharyngeal pumping continues after laser killing of the pharyngeal nervous system of C. elegans  

SciTech Connect

Using a laser microbeam to kill specific subsets of the pharyngeal nervous system of C. elegans, we found that feeding was accomplished by two separately controlled muscle motions, isthmus peristalsis and pumping. The single neuron M4 was necessary and sufficient for isthmus peristalsis. The MC neurons were necessary for normal stimulation of pumping in response to food, but pumping continued and was functional in MC- worms. The remaining 12 neuron types were also unnecessary for functional pumping. No operation we did, including destruction of the entire pharyngeal nervous system, abolished pumping altogether. When we killed all pharyngeal neurons except M4, the worms were viable and fertile, although retarded and starved. Since feeding is one of the few known essential actions controlled by the nervous system, we suggest that most of the C. elegans nervous system is dispensable in hermaphrodites under laboratory conditions. This may explain the ease with which nervous system mutants are isolated and handled in C. elegans.

Avery, L.; Horvitz, H.R. (Massachusetts Institute of Technology, Cambridge (USA))

1989-10-01

430

A C. elegans Screening Platform for the Rapid Assessment of Chemical Disruption of Germline Function  

PubMed Central

Background: Despite the developmental impact of chromosome segregation errors, we lack the tools to assess environmental effects on the integrity of the germline in animals. Objectives: We developed an assay in Caenorhabditis elegans that fluorescently marks aneuploid embryos after chemical exposure. Methods: We qualified the predictive value of the assay against chemotherapeutic agents as well as environmental compounds from the ToxCast Phase I library by comparing results from the C. elegans assay with the comprehensive mammalian in vivo end point data from the ToxRef database. Results: The assay was highly predictive of mammalian reproductive toxicities, with a 69% maximum balanced accuracy. We confirmed the effect of select compounds on germline integrity by monitoring germline apoptosis and meiotic progression. Conclusions: This C. elegans assay provides a comprehensive strategy for assessing environmental effects on germline function. PMID:23603051

Allard, Patrick; Kleinstreuer, Nicole C.; Knudsen, Thomas B.

2013-01-01

431

Motility analysis of the nematode C. elegans on wet soft media  

NASA Astrophysics Data System (ADS)

Undulatory locomotion is widely utilized by limbless organisms such as snakes, eels and worms. When moving on top of wet soft gels (e.g. agar), undulating organisms such as the nematode Caenorhabditis elegans display a motility gait that is characterized by crawling. Until present however, a detailed understanding of how C. elegans' crawling gait generates propulsion over soft gels is lacking. Namely, how much crawling force does C. elegans generate? Here, we propose a simple model based on lubrication theory to examine the biomechanics of crawling motion. In analogy to the well-known resistive-force theory (RFT) for low Reynolds number swimming, our model provides a mechanism for the linear relation between the sliding speeds and the drag forces, and sheds light on the role of grooves created by nematodes on agar. We further examine the kinematics of locomotion experimentally and compare muscle activity patterns between crawling and swimming gaits, emphasizing the inherent differences in nematode adaptability to different environments.

Sznitman, Josue; Shen, Xiaoning; Arratia, Paulo

2011-11-01

432

Strongyloides stercoralis daf-2 encodes a divergent ortholog of Caenorhabditis elegans DAF-2?  

PubMed Central

We hypothesize that developmental arrest in infectious larvae of parasitic nematodes is regulated by signaling pathways homologous to Caenorhabditis elegans DAF (dauer formation) pathways. Alignment of Strongyloides stercoralis (Ss) DAF-2 with DAF-2 of C. elegans and homologs of other species shows that most structural motifs in these insulin-like receptors are conserved. However, the catalytic domain of Ss-DAF-2 contains two substitutions (Q1242 and Q1256), that would result in constitutive dauer formation in C. elegans or diabetes in vertebrate animals. Ss-daf-2 also shows two alternately spliced isoforms, the constitutively expressed Ss-daf-2a, and Ss-daf-2b, which is only expressed in stages leading to parasitism. PMID:23500073

Massey, Holman C.; Ranjit, Najju; Stoltzfus, Jonathan D.; Lok, James B.

2013-01-01

433

?1-antitrypsin deficiency and the hepatocytes - an elegans solution to drug discovery  

PubMed Central

Hepatocytes are metabolically active cells of the liver that play an important role in the biosynthesis of proteins including ?1-antitrypsin. Mutations in the ?1-antitrypsin gene can lead to protein misfolding, polymerization/aggregation and retention of protein within the endoplasmic reticulum of hepatocytes. The intracellular accumulation of ?1-antitrypsin aggregates can lead to liver disease and increased likelihood of developing hepatocellular carcinomas. Of note, only ~10% of individuals with ?1-antitrypsin-deficiency develop severe liver disease suggesting that there are other genetic and/or environmental factors that determine disease outcome. The nematode, C. elegans, is a powerful genetic model organism to study molecular aspects of human disease. In this review, we discuss the functional similarities between the intestinal cells of C. elegans and human hepatocytes and how a C. elegans model of ?1-antitrypsin-deficiency can be used as a tool for identifying genetic modifiers and small molecule drugs. PMID:24355812

O’Reilly, Linda P.; Perlmutter, David H.; Silverman, Gary A.; Pak, Stephen C.

2014-01-01

434

Identification of two epoxide hydrolases in Caenorhabditis elegans that metabolize mammalian lipid signaling molecules.  

PubMed

We have identified two genes in the genomic database for Caenorhabditis elegans that code for proteins with significant sequence similarity to the mammalian soluble epoxide hydrolase (sEH). The respective transcripts were cloned from a mixed stage cDNA library from C. elegans. The corresponding proteins obtained after recombinant expression in insect cells hydrolyzed standard epoxide hydrolase substrates, including epoxyeicosatrienoic acids (EETs) and leukotoxins (EpOMEs). The enzyme activity was inhibited by urea-based compounds originally designed to inhibit the mammalian sEH. In vivo inhibition of the enzymes using the most potent of these compounds resulted in elevated levels of the EpOMEs in the nematode. These results suggest that the hydrolases are involved in the metabolism of possible lipid signaling molecules in C. elegans. PMID:18267101

Harris, Todd R; Aronov, Pavel A; Jones, Paul D; Tanaka, Hiromasa; Arand, Michael; Hammock, Bruce D

2008-04-15

435

Pseudomonas fluorescens NZI7 repels grazing by C. elegans, a natural predator.  

PubMed

The bacteriovorous nematode Caenorhabditis elegans has been used to investigate many aspects of animal biology, including interactions with pathogenic bacteria. However, studies examining C. elegans interactions with bacteria isolated from environments in which it is found naturally are relatively scarce. C. elegans is frequently associated with cultivation of the edible mushroom Agaricus bisporus, and has been reported to increase the severity of bacterial blotch of mushrooms, a disease caused by bacteria from the Pseudomonas fluorescens complex. We observed that pseudomonads isolated from mushroom farms showed differential resistance to nematode predation. Under nutrient poor conditions, in which most pseudomonads were consumed, the mushroom pathogenic isolate P. fluorescens NZI7 was able to repel C. elegans without causing nematode death. A draft genome sequence of NZI7 showed it to be related to the biocontrol strain P. protegens Pf-5. To identify the genetic basis of nematode repellence in NZI7, we developed a grid-based screen for mutants that lacked the ability to repel C. elegans. The mutants isolated in this screen included strains with insertions in the global regulator GacS and in a previously undescribed GacS-regulated gene cluster, 'EDB' ('edible'). Our results suggest that the product of the EDB cluster is a poorly diffusible or cell-associated factor that acts together with other features of NZI7 to provide a novel mechanism to deter nematode grazing. As nematodes interact with NZI7 colonies before being repelled, the EDB factor may enable NZI7 to come into contact with and be disseminated by C. elegans without being subject to intensive predation. PMID:23426012

Burlinson, Peter; Studholme, David; Cambray-Young, Joanna; Heavens, Darren; Rathjen, John; Hodgkin, Jonathan; Preston, Gail M

2013-06-01

436

Effects of sequential infections of Caenorhabditis elegans with Staphylococcus aureus and Proteus mirabilis.  

PubMed

Caenorhabditis elegans can be used to study the dynamics of polymicrobial infections, specifically those between Gram-positive and Gram-negative bacteria. With C. elegans, Proteus mirabilis acts as an opportunistic pathogen and does not kill this host. Hence, in the present study, C. elegans was immunochallenged by pre-infecting it with the pathogen Staphylococcus aureus in order to study the subsequent effect of P. mirabilis on the host. It was found that 12 hrs of S. aureus and 80 hrs of subsequent P. mirabilis infection significantly reduced the life span of exposed C. elegans by 80%. However, preinfection with S. aureus for 8 and 4 hrs reduced the life span of C. elegans by only 60 and 30%, respectively. Further, there was greater production of reactive oxygen species in the sequentially infected samples than in the S. aureus and P. mirabilis controls. Real time PCR analysis indicated regulation of candidate immune regulatory genes, lysozyme (lys-7), CUB-like proteins (F08G5.6), neuropeptide-like factors (nlp-29), transcription factors of mitogen-activated protein kinase (ATF-7) and daf-2-daf-16 (daf-16), insulin-like signaling pathways and C-type lectin (clec-60 and clec-87) family members during S. aureus and subsequent P. mirabilis-mediated infections, indicating possible roles of, and contributions by, the above factors during host immune responses against these sequential infections. The present findings demonstrate that S. aureus infections increase the vulnerability of the C. elegans host by subverting its immune system, which then permits the opportunistic pathogen P. mirabilis to be pathogenic to this host. PMID:22957781

JebaMercy, Gnanasekaran; Balamurugan, Krishnaswamy

2012-12-01

437

Catalase activity and innate immune response of Caenorhabditis elegans against the heavy metal toxin lead.  

PubMed

The heavy metal lead-induced oxidative stress on Caenorhabditis elegans was examined at the level of catalase activity and on innate immunity. Stress-induced C. elegans was exposed to Pseudomonas aeruginosa PA14::GFP for monitoring the impact at the physiological level. Role of catalase on the innate-immune responses of C. elegans was examined. PA14::GFP did not colonize lead pretreated C. elegans intestinal cells significantly compared to untreated controls, indicating stress-mediated upregulation of host-immunity. Semiquantitative PCR analyses of lead-exposed and PA14-infected C. elegans mRNA showed significant upregulation of candidate antimicrobial enzyme gene lys-7 after 24 h of exposures. Upregulation of metallothionein(mtl-1) when compared to mtl-2 in response to the lead suggesting active detoxification of metal by mtl-1. Exogenously provided Catalase (0.4-3.2 U) induced significant upregulation of lys-7 compared to controls. lys-7 upregulation during lead exposure was reconfirmed by real-time PCR. Confocal microscopy and fluorescence spectrophotometer analyses indicated that the lead pretreated C. elegans was significantly less colonized by PA14::GFP when compared to controls. Relative expression of ctl-1 and ctl-2 mRNA was measured using real time PCR and found to be regulated during lead exposures. Over all, the upregulation of antimicrobial gene expression appears to be correlated with the level of catalase during stress emphasizing their key roles in defensive mechanism(s). These results provide a link between the stress and related immune responses which can be explored in higher systems. PMID:21656642

Vigneshkumar, Balasubramanian; Pandian, Shunmugiah Karutha; Balamurugan, Krishnaswamy

2013-06-01

438

A Modular Library of Small Molecule Signals Regulates Social Behaviors in Caenorhabditis elegans  

PubMed Central

The nematode C. elegans is an important model for the study of social behaviors. Recent investigations have shown that a family of small molecule signals, the ascarosides, controls population density sensing and mating behavior. However, despite extensive studies of C. elegans aggregation behaviors, no intraspecific signals promoting attraction or aggregation of wild-type hermaphrodites have been identified. Using comparative metabolomics, we show that the known ascarosides are accompanied by a series of derivatives featuring a tryptophan-derived indole moiety. Behavioral assays demonstrate that these indole ascarosides serve as potent intraspecific attraction and aggregation signals for hermaphrodites, in contrast to ascarosides lacking the indole group, which are repulsive. Hermaphrodite attraction to indole ascarosides depends on the ASK amphid sensory neurons. Downstream of the ASK sensory neuron, the interneuron AIA is required for mediating attraction to indole ascarosides instead of the RMG interneurons, which previous studies have shown to integrate attraction and aggregation signals from ASK and other sensory neurons. The role of the RMG interneuron in mediating aggregation and attraction is thought to depend on the neuropeptide Y-like receptor NPR-1, because solitary and social C. elegans strains are distinguished by different npr-1 variants. We show that indole ascarosides promote attraction and aggregation in both solitary and social C. elegans strains. The identification of indole ascarosides as aggregation signals reveals unexpected complexity of social signaling in C. elegans, which appears to be based on a modular library of ascarosides integrating building blocks derived from lipid ?-oxidation and amino-acid metabolism. Variation of modules results in strongly altered signaling content, as addition of a tryptophan-derived indole unit to repellent ascarosides produces strongly attractive indole ascarosides. Our findings show that the library of ascarosides represents a highly developed chemical language integrating different neurophysiological pathways to mediate social communication in C. elegans. PMID:22253572

Bose, Neelanjan; Zaslaver, Alon; Mahanti, Parag; Ho, Margaret C.; O'Doherty, Oran G.; Edison, Arthur S.; Sternberg, Paul W.; Schroeder, Frank C.

2012-01-01

439

Functional characterisation of a cyst nematode acetylcholinesterase gene using Caenorhabditis elegans as a heterologous system.  

PubMed

Migration of plant-parasitic nematode infective larval stages through soil and invasion of roots requires perception and integration of sensory cues culminating in particular responses that lead to root penetration and parasite establishment. Components of the chemoreceptive neuronal circuitry involved in these responses are targets for control measures aimed at preventing infection. Here we report, to our knowledge, the first isolation of cyst nematode ace-2 genes encoding acetylcholinesterase (AChE). The ace-2 genes from Globodera pallida (Gp-ace-2) and Heterodera glycines (Hg-ace-2) show homology to ace-2 of Caenorhabditis elegans (Ce-ace-2). Gp-ace-2 is expressed most highly in the infective J2 stage with lowest expression in the early parasitic stages. Expression and functional analysis of the Globodera gene were carried out using the free-living nematode C. elegans in order to overcome the refractory nature of the obligate parasite G. pallida to many biological studies. Caenorhabditis elegans transformed with a GFP reporter construct under the control of the Gp-ace-2 promoter exhibited specific and restricted GFP expression in neuronal cells in the head ganglia. Gp-ACE-2 protein can functionally complement its C. elegans homologue. A chimeric construct containing the Ce-ace-2 promoter region and the Gp-ace-2 coding region and 3' untranslated region was able to restore a normal phenotype to the uncoordinated C. elegans double mutant ace-1;ace-2. This study demonstrates conservation of AChE function and expression between free-living and plant-parasitic nematode species, and highlights the utility of C. elegans as a heterologous system to study neuronal aspects of plant-parasitic nematode biology. PMID:19367833

Costa, Joana C; Lilley, Catherine J; Atkinson, Howard J; Urwin, Peter E

2009-06-01

440

On the potential for extinction by Muller's Ratchet in Caenorhabditis elegans  

PubMed Central

Background The self-fertile hermaphrodite worm C. elegans is an important model organism for biology, yet little is known about the origin and persistence of the self-fertilizing mode of reproduction in this lineage. Recent work has demonstrated an extraordinary degree of selfing combined with a high deleterious mutation rate in contemporary populations. These observations raise the question as to whether the mutation load might rise to such a degree as to eventually threaten the species with extinction. The potential for such a process to occur would inform our understanding of the time since the origin of self-fertilization in C. elegans history. Results To address this issue, here we quantify the rate of fitness decline expected to occur via Muller's ratchet for a purely selfing population, using both analytical approximations and globally distributed individual-based simulations from the evolution@home system to compute the rate of deleterious mutation accumulation. Using the best available estimates for parameters of how C. elegans evolves, we conclude that pure selfing can persist for only short evolutionary intervals, and is expected to lead to extinction within thousands of years for a plausible portion of parameter space. Credible lower-bound estimates of nuclear mutation rates do not extend the expected time to extinction much beyond a million years. Conclusion Thus we conclude that either the extreme self-fertilization implied by current patterns of genetic variation in C. elegans arose relatively recently or that low levels of outcrossing and other factors are key to the persistence of C. elegans into the present day. We also discuss results for the mitochondrial genome and the implications for C. briggsae, a close relative that made the transition to selfing independently of C. elegans. PMID:18447910

2008-01-01

441

UNC-18 modulates ethanol sensitivity in Caenorhabditis elegans.  

PubMed

Acute ethanol exposure affects the nervous system as a stimulant at low concentrations and as a depressant at higher concentrations, eventually resulting in motor dysfunction and uncoordination. A recent genetic study of two mouse strains with varying ethanol preference indicated a correlation with a polymorphism (D216N) in the synaptic protein Munc18-1. Munc18-1 functions in exocytosis via a number of discrete interactions with the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) protein syntaxin-1. We report that the mutation affects binding to syntaxin but not through either a closed conformation mode of interaction or through binding to the syntaxin N terminus. The D216N mutant instead has a specific impairment in binding the assembled SNARE complex. Furthermore, the mutation broadens the duration of single exocytotic events. Expression of the orthologous mutation (D214N) in the Caenorhabditis elegans UNC-18 null background generated transgenic rescues with phenotypically similar locomotion to worms rescued with the wild-type protein. Strikingly, D214N worms were strongly resistant to both stimulatory and sedative effects of acute ethanol. Analysis of an alternative Munc18-1 mutation (I133V) supported the link between reduced SNARE complex binding and ethanol resistance. We conclude that ethanol acts, at least partially, at the level of vesicle fusion and that its acute effects are ameliorated by point mutations in UNC-18. PMID:18923141

Graham, Margaret E; Edwards, Mark R; Holden-Dye, Lindy; Morgan, Alan; Burgoyne, Robert D; Barclay, Jeff W

2009-01-01

442

Quantification of Nociceptive Escape Response in C.elegans  

NASA Astrophysics Data System (ADS)

Animals cannot rank and communicate their pain consciously. Thus in pain studies on animal models, one must infer the pain level from high precision experimental characterization of behavior. This is not trivial since behaviors are very complex and multidimensional. Here we explore the feasibility of C.elegans as a model for pain transduction. The nematode has a robust neurally mediated noxious escape response, which we show to be partially decoupled from other sensory behaviors. We develop a nociceptive behavioral response assay that allows us to apply controlled levels of pain by locally heating worms with an IR laser. The worms' motions are captured by machine vision programming with high spatiotemporal resolution. The resulting behavioral quantification allows us to build a statistical model for inference of the experienced pain level from the behavioral response. Based on the measured nociceptive escape of over 400 worms, we conclude that none of the simple characteristics of the response are reliable indicators of the laser pulse strength. Nonetheless, a more reliable statistical inference of the pain stimulus level from the measured behavior is possible based on a complexity-controlled regression model that takes into account the entire worm behavioral output.

Leung, Kawai; Mohammadi, Aylia; Ryu, William; Nemenman, Ilya

2013-03-01

443

Sphingolipid metabolism regulates development and lifespan in Caenorhabditis elegans.  

PubMed

Sphingolipids are a highly conserved lipid component of cell membranes involved in the formation of lipid raft domains that house many of the receptors and cell-to-cell signaling factors involved in regulating cell division, maturation, and terminal differentiation. By measuring and manipulating sphingolipid metabolism using pharmacological and genetic tools in Caenorhabditis elegans, we provide evidence that the synthesis and remodeling of specific ceramides (e.g., dC18:1-C24:1), gangliosides (e.g., GM1-C24:1), and sphingomyelins (e.g., dC18:1-C18:1) influence development rate and lifespan. We found that the levels of fatty acid chain desaturation and elongation in many sphingolipid species increased during development and aging, with no such changes in developmentally-arrested dauer larvae or normal adults after food withdrawal (an anti-aging intervention). Pharmacological inhibitors and small interfering RNAs directed against serine palmitoyl transferase and glucosylceramide synthase acted to slow development rate, extend the reproductive period, and increase lifespan. In contrast, worms fed an egg yolk diet rich in sphingolipids exhibited accelerated development and reduced lifespan. Our findings demonstrate that sphingolipid accumulation and remodeling are critical events that determine development rate and lifespan in the nematode model, with both development rate and aging being accelerated by the synthesis of sphingomyelin, and its metabolism to ceramides and gangliosides. PMID:25437839

Cutler, Roy G; Thompson, Kenneth W; Camandola, Simonetta; Mack, Kendra T; Mattson, Mark P

2014-12-15

444

Response of Caenorhabditis elegans to wireless devices radiation exposure.  

PubMed

Abstract Purpose: The aim of this study was to examine the impact of electromagnetic radiation, produced by GSM (Global System for Mobile communications) mobile phones, Wi-Fi (Wireless-Fidelity) routers and wireless DECT (Digital Enhanced Cordless Telecommunications) phones, on the nematode C. elegans. Materials and methods: We exposed synchronized populations, of different developmental stages, to these wireless devices at E-field levels below ICNIRP's (International Commission on Non-Ionizing Radiation Protection) guidelines for various lengths of time. WT (wild-type) and aging- or stress-sensitive mutant worms were examined for changes in growth, fertility, lifespan, chemotaxis, short-term memory, increased ROS (Reactive Oxygen Species) production and apoptosis by using fluorescent marker genes or qRT-PCR (quantitative Reverse Transcription-Polymerase Chain Reaction). Results: No statistically significant differences were found between the exposed and the sham/control animals in any of the experiments concerning lifespan, fertility, growth, memory, ROS, apoptosis or gene expression. Conclusions: The worm appears to be robust to this form of (pulsed) radiation, at least under the exposure conditions used. PMID:25488006

Fasseas, Michael K; Fragopoulou, Adamantia F; Manta, Areti K; Skouroliakou, Aikaterini; Vekrellis, Konstantinos; Margaritis, Lukas H; Syntichaki, Popi

2014-12-01

445

Centrosome size sets mitotic spindle length in Caenorhabditis elegans embryos.  

PubMed

Just as the size of an organism is carefully controlled, the size of intracellular structures must also be regulated. The mitotic spindle is a supramolecular machine that generates the forces which separate sister chromatids during mitosis. Although spindles show little size variation between cells of the same type, spindle length can vary at least 10-fold between different species. Recent experiments on spindle length showed that in embryonic systems spindle length varied with blastomere size. Furthermore, a comparison between two Xenopus species showed that spindle length was dependent on some cytoplasmic factor. These data point toward mechanisms to scale spindle length with cell size. Centrosomes play an important role in organizing microtubules during spindle assembly. Here we use Caenorhabditis elegans to study the role of centrosomes in setting spindle length. We show that spindle length correlates with centrosome size through development and that a reduction of centrosome size by molecular perturbation reduces spindle length. By systematically analyzing centrosome proteins, we show that spindle length does not depend on microtubule density at centrosomes. Rather, our data suggest that centrosome size sets mitotic spindle length by controlling the length scale of a TPXL-1 gradient along spindle microtubules. PMID:20137951

Greenan, Garrett; Brangwynne, Clifford P; Jaensch, Steffen; Gharakhani, Jöbin; Jülicher, Frank; Hyman, Anthony A

2010-02-23

446

A variety of dicer substrates in human and C. elegans.  

PubMed

The endoribonuclease Dicer is known for its central role in the biogenesis of eukaryotic small RNAs/microRNAs. Despite its importance, Dicer target transcripts have not been directly mapped. Here, we apply biochemical methods to human cells and C. elegans and identify thousands of Dicer-binding sites. We find known and hundreds of additional miRNAs with high sensitivity and specificity. We also report structural RNAs, promoter RNAs, and mitochondrial transcripts as Dicer targets. Interestingly, most Dicer-binding sites reside on mRNAs/lncRNAs and are not significantly processed into small RNAs. These passive sites typically harbor small, Dicer-bound hairpins within intact transcripts and generally stabilize target expression. We show that passive sites can sequester Dicer and reduce microRNA expression. mRNAs with passive sites were in human and worm significantly associated with processing-body/granule function. Together, we provide the first transcriptome-wide map of Dicer targets and suggest conserved binding modes and functions outside of the miRNA pathway. PMID:25416952

Rybak-Wolf, Agnieszka; Jens, Marvin; Murakawa, Yasuhiro; Herzog, Margareta; Landthaler, Markus; Rajewsky, Nikolaus

2014-11-20

447

Analysis of centriole elimination during C. elegans oogenesis  

PubMed Central

Centrosomes are the principal microtubule organizing centers (MTOCs) of animal cells and comprise a pair of centrioles surrounded by pericentriolar material (PCM). Centriole number must be carefully regulated, notably to ensure bipolar spindle formation and thus faithful chromosome segregation. In the germ line of most metazoan species, centrioles are maintained during spermatogenesis, but eliminated during oogenesis. Such differential behavior ensures that the appropriate number of centrioles is present in the newly fertilized zygote. Despite being a fundamental feature of sexual reproduction in metazoans, the mechanisms governing centriole elimination during oogenesis are poorly understood. Here, we investigate this question in C. elegans. Using antibodies directed against centriolar components and serial-section electron microscopy, we establish that centrioles are eliminated during the diplotene stage of the meiotic cell cycle. Moreover, we show that centriole elimination is delayed upon depletion of the helicase CGH-1. We also find that somatic cells make a minor contribution to this process, and demonstrate that the germ cell karyotype is important for timely centriole elimination. These findings set the stage for a mechanistic dissection of centriole elimination in a metazoan organism. PMID:22492357

Mikeladze-Dvali, Tamara; von Tobel, Lukas; Strnad, Petr; Knott, Graham; Leonhardt, Heinrich; Schermelleh, Lothar; Gönczy, Pierre

2012-01-01

448

Insulin signaling promotes germline proliferation in C. elegans  

PubMed Central

Cell proliferation must be coordinated with cell fate specification during development, yet interactions among pathways that control these two critical aspects of development are not well understood. The coordination of cell fate specification and proliferation is particularly crucial during early germline development, when it impacts the establishment of stem/progenitor cell populations and ultimately the production of gametes. In C. elegans, insulin/IGF-like receptor (IIR) signaling has been implicated in fertility, but the basis for the fertility defect had not been previously characterized. We found that IIR signaling is required for robust larval germline proliferation, separate from its well-characterized role in preventing dauer entry. IIR signaling stimulates the larval germline cell cycle. This activity is distinct from Notch signaling, occurs in a predominantly germline-autonomous manner, and responds to somatic activity of ins-3 and ins-33, genes that encode putative insulin-like ligands. IIR signaling in this role acts through the canonical PI3K pathway, inhibiting DAF-16/FOXO. However, signaling from these ligands does not inhibit daf-16 in neurons nor in the intestine, two tissues previously implicated in other IIR roles. Our data are consistent with a model in which: (1) under replete reproductive conditions, the larval germline responds to insulin signaling to ensure robust germline proliferation that builds up the germline stem cell population; and (2) distinct insulin-like ligands contribute to different phenotypes by acting on IIR signaling in different tissues. PMID:20110332

Michaelson, David; Korta, Dorota Z.; Capua, Yossi; Hubbard, E. Jane Albert

2010-01-01

449

The dynamics of replication licensing in live Caenorhabditis elegans embryos  

PubMed Central

Accurate DNA replication requires proper regulation of replication licensing, which entails loading MCM-2–7 onto replication origins. In this paper, we provide the first comprehensive view of replication licensing in vivo, using video microscopy of Caenorhabditis elegans embryos. As expected, MCM-2–7 loading in late M phase depended on the prereplicative complex (pre-RC) proteins: origin recognition complex (ORC), CDC-6, and CDT-1. However, many features we observed have not been described before: GFP–ORC-1 bound chromatin independently of ORC-2–5, and CDC-6 bound chromatin independently of ORC, whereas CDT-1 and MCM-2–7 DNA binding was interdependent. MCM-3 chromatin loading was irreversible, but CDC-6 and ORC turned over rapidly, consistent with ORC/CDC-6 loading multiple MCM-2–7 complexes. MCM-2–7 chromatin loading further reduced ORC and CDC-6 DNA binding. This dynamic behavior creates a feedback loop allowing ORC/CDC-6 to repeatedly load MCM-2–7 and distribute licensed origins along chromosomal DNA. During S phase, ORC and CDC-6 were excluded from nuclei, and DNA was overreplicated in export-defective cells. Thus, nucleocytoplasmic compartmentalization of licensing factors ensures that DNA replication occurs only once. PMID:22249291

Sonneville, Remi; Querenet, Matthieu; Craig, Ashley

2012-01-01

450

Characterization of Caenorhabditis Elegans Lectin-Binding Mutants  

PubMed Central

We have identified 45 mutants of Caenorhabditis elegans that show ectopic surface binding of the lectins wheat germ agglutinin (WGA) and soybean agglutinin (SBA). These mutations are all recessive and define six genes: srf-2, srf-3, srf-4, srf-5, srf-8 and srf-9. Mutations in these genes fall into two phenotypic classes: srf-2, -3, -5 mutants are grossly wild-type, except for their lectin-binding phenotype; srf-4, -8, -9 mutants have a suite of defects, including uncoordinated movement, abnormal egg laying, and defective copulatory bursae morphogenesis. Characterization of these pleiotropic mutants at the cellular level reveals defects in the migration of the gonadal distal tip cell and in axon morphology. Unexpectedly, the pleiotropic mutations also interact with mutations in the lin-12 gene, which encodes a putative cell surface receptor involved in the control of cell fate. We propose that the underlying defect in the pleiotropic mutations may be in the general processing or secretion of extracellular proteins. PMID:1516818

Link, C. D.; Silverman, M. A.; Breen, M.; Watt, K. E.; Dames, S. A.

1992-01-01

451

A remote control for the C. elegans nervous system  

NASA Astrophysics Data System (ADS)

We demonstrate a closed-loop optogenetic illumination system to stimulate or inhibit arbitrary patterns of neurons and muscle in a freely roaming worm. Transgenic worms that express light-sensitive ion channels in neurons or muscle are used. A microscope with a video camera records the worm's posture and motion. As the worm moves unrestrained, custom real-time image processing software analyzes the worm's position and estimates the location of targeted muscle and neuron cells. For each frame captured by the camera, the software generates an illumination pattern and directs a digital mirror device to shine laser light onto the targeted cells. The system can illuminate an arbitrary spatial and temporal pattern and thus can selectively inhibit or stimulate different sets of cells during the course of a single experiment. The image processing software is very fast and analyzes a 1024 by 768 pixel image containing a worm in less than 10ms. The system has been tested using worms expressing Channelrhodopsin and Halorhodopsin in both neurons and muscle. Preliminary results from an investigation of the C. elegans motor circuit are shown.

Leifer, Andrew M.; Fang-Yen, Christopher; Samuel, Aravinthan D. T.

2010-03-01

452

Selection against males in Caenorhabditis elegans under two mutational treatments  

PubMed Central

Within populations with mixed mating systems, selfing is expected to be favoured over outcrossing unless a countervailing process such as severe inbreeding depression is present. In this study, we consider the relationship between the expression of deleterious alleles and the maintenance of outcrossing in the nematode species, Caenorhabditis elegans. This species is characterized by an androdioecious breeding system composed of males at low frequency and self-fertilizing hermaphrodites that can only outcross via males. Here, we find that experimentally increasing the mutational load in four different isogenic wild isolates using 10 generations of Ethylmethane sulphonate (EMS) and UV irradiation mutagenesis significantly diminishes the cost of males. Males are maintained at higher frequencies in mutagenized versus non-mutagenized populations. Nevertheless, males still tend to be driven to low frequencies within isolates that are known to be prone to lose males. Further, we determine the viability effects of a single round of mutagen exposure and find that, for EMS, outcrossing overcomes the almost completely recessive and nearly lethal effects generated. We briefly interpret our results in light of current evolutionary theory of outcrossing rates. PMID:17164206

Manoel, Diogo; Carvalho, Sara; Phillips, Patrick C; Teotónio, Henrique

2006-01-01

453

mRNA surveillance by the Caenorhabditis elegans smg genes.  

PubMed

mRNAs that contain premature stop codons are unstable in most eukaryotes, but the mechanism of their degradation is largely unknown. We demonstrate that functions of the six C. elegans smg genes are necessary for rapid turnover of nonsense mutant mRNAs of the unc-54 myosin heavy chain gene. Nonsense alleles of unc-54 express mRNAs that are unstable in smg(+) genetic backgrounds but have normal or near normal stability in smg(-) backgrounds. smg mutations also stabilize mRNA of unc-54(r293), a small deletion that removes the unc-54 polyadenylation site and expresses an aberrant mRNA. Most unc-54 nonsense mutations are recessive in both smg(+) and smg(-) genetic backgrounds. However, four specific alleles are recessive when smg(+) and dominant when smg(-). These smg-dependent dominant alleles express nonsense mutant polypeptides that disrupt thick filament and/or sarcomere assembly. All four alleles are predicted to express nonsense fragment polypeptides that contain most of the myosin globular head domain without an attached rod segment. By degrading messages that contain premature stop codons, the smg genes eliminate mRNAs that encode potentially toxic protein fragments. We propose that this system of mRNA turnover protects cells from their own errors of transcription, mRNA processing, or mRNA transport. PMID:8104846

Pulak, R; Anderson, P

1993-10-01

454

Insertion and excision of Caenorhabditis elegans transposable element Tc1.  

PubMed

The transposable element Tc1 is responsible for most spontaneous mutations that occur in Caenorhabditis elegans variety Bergerac. We investigated the genetic and molecular properties of Tc1 transposition and excision. We show that Tc1 insertion into the unc-54 myosin heavy-chain gene was strongly site specific. The DNA sequences of independent Tc1 insertion sites were similar to each other, and we present a consensus sequence for Tc1 insertion that describes these similarities. We show that Tc1 excision was usually imprecise. Tc1 excision was imprecise in both germ line and somatic cells. Imprecise excision generated novel unc-54 alleles that had amino acid substitutions, amino acid insertions, and, in certain cases, probably altered mRNA splicing. The DNA sequences remaining after Tc1 somatic excision were the same as those remaining after germ line excision, but the frequency of somatic excision was at least 1,000-fold higher than that of germ line excision. The genetic properties of Tc1 excision, combined with the DNA sequences of the resulting unc-54 alleles, demonstrated that excision was dependent on Tc1 transposition functions in both germ line and somatic cells. Somatic excision was not regulated in the same strain-specific manner as germ-line excision was. In a genetic background where Tc1 transposition and excision in the germ line was not detectable, Tc1 excision in the soma still occurred at high frequency. PMID:2832734

Eide, D; Anderson, P

1988-02-01

455

Natural and Unanticipated Modifiers of RNAi Activity in Caenorhabditis elegans  

PubMed Central

Organisms used as model genomics systems are maintained as isogenic strains, yet evidence of sequence differences between independently maintained wild-type stocks has been substantiated by whole-genome resequencing data and strain-specific phenotypes. Sequence differences may arise from replication errors, transposon mobilization, meiotic gene conversion, or environmental or chemical assault on the genome. Low frequency alleles or mutations with modest effects on phenotypes can contribute to natural variation, and it has proven possible for such sequences to become fixed by adapted evolutionary enrichment and identified by resequencing. Our objective was to identify and analyze single locus genetic defects leading to RNAi resistance in isogenic strains of Caenorhabditis elegans. In so doing, we uncovered a mutation that arose de novo in an existing strain, which initially frustrated our phenotypic analysis. We also report experimental, environmental, and genetic conditions that can complicate phenotypic analysis of RNAi pathway defects. These observations highlight the potential for unanticipated mutations, coupled with genetic and environmental phenomena, to enhance or suppress the effects of known mutations and cause variation between wild-type strains. PMID:23209671

Asad, Nadeem; Aw, Wen Yih; Timmons, Lisa

2012-01-01

456

PTEN Negatively Regulates MAPK Signaling during Caenorhabditis elegans Vulval Development  

PubMed Central

Vulval development in Caenorhabditis elegans serves as an excellent model to examine the crosstalk between different conserved signaling pathways that are deregulated in human cancer. The concerted action of the RAS/MAPK, NOTCH, and WNT pathways determines an invariant pattern of cell fates in three vulval precursor cells. We have discovered a novel form of crosstalk between components of the Insulin and the RAS/MAPK pathways. The insulin receptor DAF-2 stimulates, while DAF-18 PTEN inhibits, RAS/MAPK signaling in the vulval precursor cells. Surprisingly, the inhibitory activity of DAF-18 PTEN on the RAS/MAPK pathway is partially independent of its PIP3 lipid phosphatase activity and does not involve further downstream components of the insulin pathway, such as AKT and DAF-16 FOXO. Genetic and biochemical analyses indicate that DAF-18 negatively regulates vulval induction by inhibiting MAPK activation. Thus, mutations in the PTEN tumor suppressor gene may result in the simultaneous hyper-activation of two oncogenic signaling pathways. PMID:22916028

Nakdimon, Itay; Walser, Michael; Fröhli, Erika; Hajnal, Alex

2012-01-01

457

Genetic control of temperature preference in the nematode Caenorhabditis elegans.  

PubMed

Animals modify behavioral outputs in response to environmental changes. C. elegans exhibits thermotaxis, where well-fed animals show attraction to their cultivation temperature on a thermal gradient without food. We show here that feeding-state-dependent modulation of thermotaxis is a powerful behavioral paradigm for elucidating the mechanism underlying neural plasticity, learning, and memory in higher animals. Starved experience alone could induce aversive response to cultivation temperature. Changing both cultivation temperature and feeding state simultaneously evoked transient attraction to or aversion to the previous cultivation temperature: recultivation of starved animals with food immediately induced attraction to the temperature associated with starvation, although the animals eventually exhibited thermotaxis to the new temperature associated with food. These results suggest that the change in feeding state quickly stimulates the switch between attraction and aversion for the temperature in memory and that the acquisition of new temperature memory establishes more slowly. We isolated aho (abnormal hunger orientation) mutants that are defective in starvation-induced cultivation-temperature avoidance. Some aho mutants responded normally to changes in feeding state with respect to locomotory activity, implying that the primary thermosensation followed by temperature memory formation remains normal and the modulatory aspect of thermotaxis is specifically impaired in these mutants. PMID:15654086

Mohri, Akiko; Kodama, Eiji; Kimura, Koutarou D; Koike, Mizuho; Mizuno, Takafumi; Mori, Ikue

2005-03-01

458

Dissecting a circuit for olfactory behaviour in Caenorhabditis elegans.  

PubMed

Although many properties of the nervous system are shared among animals and systems, it is not known whether different neuronal circuits use common strategies to guide behaviour. Here we characterize information processing by Caenorhabditis elegans olfactory neurons (AWC) and interneurons (AIB and AIY) that control food- and odour-evoked behaviours. Using calcium imaging and mutations that affect specific neuronal connections, we show that AWC neurons are activated by odour removal and activate the AIB interneurons through AMPA-type glutamate receptors. The level of calcium in AIB interneurons is elevated for several minutes after odour removal, a neuronal correlate to the prolonged behavioural response to odour withdrawal. The AWC neuron inhibits AIY interneurons through glutamate-gated chloride channels; odour presentation relieves this inhibition and results in activation of AIY interneurons. The opposite regulation of AIY and AIB interneurons generates a coordinated behavioural response. Information processing by this circuit resembles information flow from vertebrate photoreceptors to 'OFF' bipolar and 'ON' bipolar neurons, indicating a conserved or convergent strategy for sensory information processing. PMID:17972877

Chalasani, Sreekanth H; Chronis, Nikos; Tsunozaki, Makoto; Gray, Jesse M; Ramot, Daniel; Goodman, Miriam B; Bargmann, Cornelia I

2007-11-01

459

Temporal Analysis of Stochastic Turning Behavior of Swimming C. elegans  

PubMed Central

Caenorhabditis elegans exhibits spontaneous motility in isotropic environments, characterized by periods of forward movements punctuated at random by turning movements. Here, we study the statistics of turning movements—deep ?-shaped bends—exhibited by swimming worms. We show that the durations of intervals between successive ?-turns are uncorrelated with one another and are effectively selected from a probability distribution resembling the sum of two exponentials. The worm initially exhibits frequent ?-turns on being placed in liquid, and the mean rate of ?-turns lessens over time. The statistics of ?-turns is consistent with a phenomenological model involving two behavioral states governed by Poisson kinetics: a “slow” state generates ?-turns with a low probability per unit time; a “fast” state generates ?-turns with a high probability per unit time; and the worm randomly transitions between these slow and fast states. Our findings suggest that the statistics of spontaneous ?-turns exhibited by swimming worms may be described using a small number of parameters, consistent with a two-state phenomenological model for the mechanisms that spontaneously generate ?-turns. PMID:19535479

Srivastava, Nikhil; Clark, Damon A.; Samuel, Aravinthan D.T.

2009-01-01

460

Genetic Regulation of Caenorhabditis elegans Lysosome Related Organelle Function  

PubMed Central

Lysosomes are membrane-bound organelles that contain acid hydrolases that degrade cellular proteins, lipids, nucleic acids, and oligosaccharides, and are important for cellular maintenance and protection against age-related decline. Lysosome related organelles (LROs) are specialized lysosomes found in organisms from humans to worms, and share many of the features of classic lysosomes. Defective LROs are associated with human immune disorders and neurological disease. Caenorhabditis elegans LROs are the site of concentration of vital dyes such as Nile red as well as age-associated autofluorescence. Even though certain short-lived mutants have high LRO Nile red and high autofluorescence, and other long-lived mutants have low LRO Nile red and low autofluorescence, these two biologies are distinct. We identified a genetic pathway that modulates aging-related LRO phenotypes via serotonin signaling and the gene kat-1, which encodes a mitochondrial ketothiolase. Regulation of LRO phenotypes by serotonin and kat-1 in turn depend on the proton-coupled, transmembrane transporter SKAT-1. skat-1 loss of function mutations strongly suppress the high LRO Nile red accumulation phenotype of kat-1 mutation. Using a systems approach, we further analyzed the role of 571 genes in LRO biology. These results highlight a gene network that modulates LRO biology in a manner dependent upon the conserved protein kinase TOR complex 2. The results implicate new genetic pathways involved in LRO biology, aging related physiology, and potentially human diseases of the LRO. PMID:24204312

Soukas, Alexander A.; Carr, Christopher E.; Ruvkun, Gary

2013-01-01

461

Family of FLP Peptides in Caenorhabditis elegans and Related Nematodes.  

PubMed

Neuropeptides regulate all aspects of behavior in multicellular organisms. Because of their ability to act at long distances, neuropeptides can exert their effects beyond the conventional synaptic connections, thereby adding an intricate layer of complexity to the activity of neural networks. In the nematode Caenorhabditis elegans, a large number of neuropeptide genes that are expressed throughout the nervous system have been identified. The actions of these peptides supplement the synaptic connections of the 302 neurons, allowing for fine tuning of neural networks and increasing the ways in which behaviors can be regulated. In this review, we focus on a large family of genes encoding FMRFamide-related peptides (FaRPs). These genes, the flp genes, have been used as a starting point to identifying flp genes throughout Nematoda. Nematodes have the largest family of FaRPs described thus far. The challenges in the future are the elucidation of their functions and the identification of the receptors and signaling pathways through which they function. PMID:25352828

Li, Chris; Kim, Kyuhyung

2014-01-01

462

Pseudomonas aeruginosa PAO1 Kills Caenorhabditis elegans by Cyanide Poisoning  

PubMed Central

In this report we describe experiments to investigate a simple virulence model in which Pseudomonas aeruginosa PAO1 rapidly paralyzes and kills the nematode Caenorhabditis elegans. Our results imply that hydrogen cyanide is the sole or primary toxic factor produced by P. aeruginosa that is responsible for killing of the nematode. Four lines of evidence support this conclusion. First, a transposon insertion mutation in a gene encoding a subunit of hydrogen cyanide synthase (hcnC) eliminated nematode killing. Second, the 17 avirulent mutants examined all exhibited reduced cyanide synthesis, and the residual production levels correlated with killing efficiency. Third, exposure to exogenous cyanide alone at levels comparable to the level produced by PAO1 killed nematodes with kinetics similar to those observed with bacteria. The killing was not enhanced if hcnC mutant bacteria were present during cyanide exposure. And fourth, a nematode mutant (egl-9) resistant to P. aeruginosa was also resistant to killing by exogenous cyanide in the absence of bacteria. A model for nematode killing based on inhibition of mitochondrial cytochrome oxidase is presented. The action of cyanide helps account for the unusually broad host range of virulence of P. aeruginosa and may contribute to the pathogenesis in opportunistic human infections due to the bacterium. PMID:11591663

Gallagher, Larry A.; Manoil, Colin

2001-01-01

463

Whole-Genome Profiling of Mutagenesis in Caenorhabditis elegans  

PubMed Central

Deep sequencing offers an unprecedented view of an organism's genome. We describe the spectrum of mutations induced by three commonly used mutagens: ethyl methanesulfonate (EMS), N-ethyl-N-nitrosourea (ENU), and ultraviolet trimethylpsoralen (UV/TMP) in the nematode Caenorhabditis elegans. Our analysis confirms the strong GC to AT transition bias of EMS. We found that ENU mainly produces A to T and T to A transversions, but also all possible transitions. We found no bias for any specific transition or transversion in the spectrum of UV/TMP-induced mutations. In 10 mutagenized strains we identified 2723 variants, of which 508 are expected to alter or disrupt gene function, including 21 nonsense mutations and 10 mutations predicted to affect mRNA splicing. This translates to an average of 50 informative mutations per strain. We also present evidence of genetic drift among laboratory wild-type strains derived from the Bristol N2 strain. We make several suggestions for best practice using massively parallel short read sequencing to ensure mutation detection. PMID:20439774

Flibotte, Stephane; Edgley, Mark L.; Chaudhry, Iasha; Taylor, Jon; Neil, Sarah E.; Rogula, Aleksandra; Zapf, Rick; Hirst, Martin; Butterfield, Yaron; Jones, Steven J.; Marra, Marco A.; Barstead, Robert J.; Moerman, Donald G.

2010-01-01

464

Uncoupling lifespan and healthspan in Caenorhabditis elegans longevity mutants.  

PubMed

Aging research has been very successful at identifying signaling pathways and evolutionarily conserved genes that extend lifespan with the assumption that an increase in lifespan will also increase healthspan. However, it is largely unknown whether we are extending the healthy time of life or simply prolonging a period of frailty with increased incidence of age-associated diseases. Here we use Caenorhabditis elegans, one of the premiere systems for lifespan studies, to determine whether lifespan and healthspan are intrinsically correlated. We conducted multiple cellular and organismal assays on wild type as well as four long-lived mutants (insulin/insulin-like growth factor-1, dietary restriction, protein translation, mitochondrial signaling) in a longitudinal manner to determine the health of the an