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1

Tcl transposition and mutator activity in a Bristol strain of Caenorhabditis elegans  

Microsoft Academic Search

In most strains of Caenorhabditis elegans with a low copy number of Tc1 transposable elements, germline transposition is rare or undetectable. We have observed low-level Tel transposition in the genome of the C. elegans var. Bristol strain KR579 (unc-13[e51]) resulting in an increase in Tc1 copy number and subsequent mutator activity. Examination of genomic blots from KR579 and KR579derived strains

J. M. Babity; T. V. B. Starr; A. M. Rose

1990-01-01

2

var2 genetic suppressors  

Microsoft Academic Search

The Arabidopsis variegation2 (var2) mutant, displaying a conspicuous green and white sectoring phenotype, is one of the most well-characterized variegation mutants and is the caused by mutations in VAR2, which encodes a subunit of the FtsH metalloprotease complex situated in the chloroplast thylakoid membranes. FtsH proteins mediate a myriad of processes in plants, the most prominent one being the turnover

Xiayan Liu

2010-01-01

3

Inocybe hirsuta var. maxima  

NSDL National Science Digital Library

Inocybe hirsuta var. maxima A. H. Smith (SAT 01-279-08) photographed in the Hoh River Valley in Olympic National Park, Washington, USA. This variety is common in Washington under western hemlock and is also known from eastern North America under eastern hemlock.

Trudell, Steve

2004-03-09

4

Neural Regeneration in Caenorhabditis elegans  

PubMed Central

Axon regeneration is a medically relevant process that can repair damaged neurons. This review describes current progress in understanding axon regeneration in the model organism Caenorhabditis elegans. Factors that regulate axon regeneration in C. elegans have broadly similar roles in vertebrate neurons. This means that using C. elegans as a tool to leverage discovery is a legitimate strategy for identifying conserved mechanisms of axon regeneration.

El Bejjani, Rachid; Hammarlund, Marc

2013-01-01

5

C. elegans Mating  

NSDL National Science Digital Library

Video microscopy of mating between a male and a hermaphrodite C. elegans roundworm. This video featured on the HHMI DVD, The Meaning of Sex: Genes and Gender, available free from HHMI. Also, this video is 56 seconds in length, and available in Quicktime (2 MB) and Windows Media (3 MB). All sex determination videos are located at: http://www.hhmi.org/biointeractive/gender/video.html.

Howard Hughes Medical Institute (Howard Hughes Medical Institute;)

2008-06-06

6

Laser Microsurgery in Caenorhabditis elegans  

PubMed Central

Laser killing of cell nuclei has long been a powerful means of examining the roles of individual cells in C. elegans. Advances in genetics, laser technology, and imaging have further expanded the capabilities and usefulness of laser surgery. Here, we review the implementation and application of currently used methods for target edoptical disruption in C. elegans.

Fang-Yen, Christopher; Gabel, Christopher V.; Samuel, Aravinthan D. T.; Bargmann, Cornelia I.; Avery, Leon

2013-01-01

7

Sensory signaling in Caenorhabditis elegans  

Microsoft Academic Search

The simple anatomy, behavior, and genetics of the nematode Caenorhabditis elegans make it an attractive organism for studying sensory circuits and their functions in vivo. Recent advances in our understanding of C. elegans sensory signaling stem from work on topographic maps, chemosensory receptors, modality coding, and the integration of antagonistic sensory inputs.

Joshua M Kaplan

1996-01-01

8

Method for Producing 'Lilium elegans'.  

National Technical Information Service (NTIS)

The invention relates to products and methods for the production of lily plants specifically Lilium elegans Thunb., from bulbils produced in leaf axils and Lilium Longiflorum Thunb., lilies produced from seedlings or bulblets derived from tissue culture o...

M. S. Roh

1990-01-01

9

Ethanol preference in C. elegans.  

PubMed

Caenorhabditis elegans senses multiple environmental stimuli through sensory systems and rapidly changes its behaviors for survival. With a simple and well-characterized nervous system, C. elegans is a suitable animal model for studying behavioral plasticity. Previous studies have shown acute neurodepressive effects of ethanol on multiple behaviors of C. elegans similar to the effect of ethanol on other organisms. Caenorhabditis elegans also develops ethanol tolerance during continuous exposure to ethanol. In mammals, chronic ethanol exposure leads to ethanol tolerance as well as increased ethanol consumption. Ethanol preference is associated with the development of tolerance and may lead to the development of ethanol dependence. In this study, we show that C. elegans is a useful model organism for studying chronic effects of ethanol, including the development of ethanol preference. We designed a behavioral assay for testing ethanol preference after prolonged ethanol exposure. Despite baseline aversive responses to ethanol, animals show ethanol preference after 4 h of pre-exposure to ethanol and exhibit significantly enhanced preference for ethanol after a lifetime of ethanol exposure. The cat-2 and tph-1 mutant animals have defects in the synthetic enzymes for dopamine and serotonin, respectively. These mutants are deficient in the development of ethanol preference, indicating that dopamine and serotonin are required for this form of behavioral plasticity. PMID:19614755

Lee, J; Jee, C; McIntire, S L

2009-06-22

10

C. elegans feeding.  

PubMed

C. elegans feeding depends on the action of the pharynx, a neuromuscular pump that joins the mouth to the intestine. The pharyngeal muscle captures food-bacteria-and transports it back to the intestine. It accomplishes this through a combination of two motions, pumping and isthmus peristalsis. Pumping, the most visible and best understood of the two, is a cycle of contraction and relaxation that sucks in liquid from the surrounding environment along with suspended particles, then expels the liquid, trapping the particles. Pharyngeal muscle is capable of pumping without nervous system input, but during normal rapid feeding its timing is controlled by two pharyngeal motor neuron types. Isthmus peristalsis, a posterior moving wave of contraction of the muscle of the posterior isthmus, depends on a third motor neuron type. Feeding motions are regulated by the presence and quality of food in the worm's environment. Some types of bacteria are better at supporting growth than others. Given a choice, worms are capable of identifying and seeking out higher-quality food. Food availability and quality also affect behavior in other ways. For instance, given all the high-quality food they can eat, worms eventually become satiated, stop eating and moving, and become quiescent. PMID:22628186

Avery, Leon; You, Young-Jai

2012-05-21

11

CAENORHABDITIS ELEGANS Deficiency Mapping  

PubMed Central

Six schemes were used to identify 80 independent recessive lethal deficiencies of linkage group (LG) II following X-ray treatment of the nematode Caenorhabditis elegans. Complementation tests between the deficiencies and ethyl methanesulfonate-induced recessive visible, lethal and sterile mutations and between different deficiencies were used to characterize the extents of the deficiencies. Deficiency endpoints thus helped to order 36 sites within a region representing about half of the loci on LG II and extending over about 5 map units. New mutations occurring in this region can be assigned to particular segments of the map by complementation tests against a small number of deficiencies; this facilitates the assignment of single-site mutations to particular genes, as we illustrate. Five sperm-defective and five oocyte-defective LG II sterile mutants were identified and mapped. Certain deficiency-by-deficiency complementation tests allowed us to suggest that the phenotypes of null mutations at two loci represented by visible alleles are wild type and that null mutations at a third locus confer a visible phenotype. A segment of LG II that is about 12 map units long and largely devoid of identified loci seems to be greatly favored for crossing over.

Sigurdson, D. Christine; Spanier, Gail J.; Herman, Robert K.

1984-01-01

12

C. elegans feeding*  

PubMed Central

C. elegans feeding depends on the action of the pharynx, a neuromuscular pump that joins the mouth to the intestine. The pharyngeal muscle captures food—bacteria—and transports it back to the intestine. It accomplishes this through a combination of two motions, pumping and isthmus peristalsis. Pumping, the most visible and best understood of the two, is a cycle of contraction and relaxation that sucks in liquid from the surrounding environment along with suspended particles, then expels the liquid, trapping the particles. Pharyngeal muscle is capable of pumping without nervous system input, but during normal rapid feeding its timing is controlled by two pharyngeal motor neuron types. Isthmus peristalsis, a posterior moving wave of contraction of the muscle of the posterior isthmus, depends on a third motor neuron type. Feeding motions are regulated by the presence and quality of food in the worm's environment. Some types of bacteria are better at supporting growth than others. Given a choice, worms are capable of identifying and seeking out higher-quality food. Food availability and quality also affect behavior in other ways. For instance, given all the high-quality food they can eat, worms eventually become satiated, stop eating and moving, and become quiescent.

Avery, Leon; You, Young-Jai

2013-01-01

13

Biolistic transformation of Caenorhabditis elegans.  

PubMed

The ability to generate transgenic animals to study gene expression and function is a powerful and important part of the Caenorhabditis elegans genetic toolbox. Transgenic animals can be created by introducing exogenous DNA into the worm germline either by microinjection or by microparticle bombardment (biolistic transformation). In this chapter we describe a simple and robust protocol to generate transgenic C. elegans animals by biolistic transformation with gold particles using the Bio-Rad PDS-1000/He system with Hepta adapter and unc-119 selection marker. We also point out the steps that need special attention to achieve successful transformations. PMID:23104335

Isik, Meltem; Berezikov, Eugene

2013-01-01

14

Structural Analysis of Cointegrating VARs  

Microsoft Academic Search

This survey uses a number of recent developments in the analysis of cointegrating Vector Autoregressions (VARs) to examine their links to the older structural modelling traditions using Autoregressive Distributed Lag (ARDL), and Simultaneous Equations Models (SEMs). In particular, it emphasizes the importance of using judgement and economic theory to supplement the statistical information. After a brief historical review it sets

M. Hashem Pesaran; Ron P. Smith

1998-01-01

15

The kinetochores of Caenorhabditis elegans  

Microsoft Academic Search

Light microscopy of the mitotic chromosomes of Caenorhabditis elegans suggests that non-localized kinetochores are present, since the chromosomes appear as stiff rods 1 to 2 µm in length and lack any visible constriction. The holokinetic structure was confirmed by reconstructions of electron micrographs of dividing nuclei in serially sectioned embryos. In prophase the kinetochore appears as an amorphous projection approximately

Donna G. Albertson; J. Nichol Thomson

1982-01-01

16

Proteomic analysis of Caenorhabditis elegans  

Technology Transfer Automated Retrieval System (TEKTRAN)

Proteomic studies of the free-living nematode Caenorhabditis elegans have recently received great attention because this animal is a useful model platform for the in vivo study of various biological problems relevant to human disease. In general, proteomic analysis is performed in order to address a...

17

The elegans of spindle assembly  

PubMed Central

The Caenorhabditis elegans one-cell embryo is a powerful system in which to study microtubule organization because this large cell assembles both meiotic and mitotic spindles within the same cytoplasm over the course of 1 h in a stereotypical manner. The fertilized oocyte assembles two consecutive acentrosomal meiotic spindles that function to reduce the replicated maternal diploid set of chromosomes to a single-copy haploid set. The resulting maternal DNA then unites with the paternal DNA to form a zygotic diploid complement, around which a centrosome-based mitotic spindle forms. The early C. elegans embryo is amenable to live-cell imaging and electron tomography, permitting a detailed structural comparison of the meiotic and mitotic modes of spindle assembly.

Greenan, Garrett; O'Toole, Eileen

2010-01-01

18

The Nucleolus of Caenorhabditis elegans  

PubMed Central

Nucleolar size and appearance correlate with ribosome biogenesis and cellular activity. The mechanisms underlying changes in nucleolar appearance and regulation of nucleolar size that occur during differentiation and cell cycle progression are not well understood. Caenorhabditis elegans provides a good model for studying these processes because of its small size and transparent body, well-characterized cell types and lineages, and because its cells display various sizes of nucleoli. This paper details the advantages of using C. elegans to investigate features of the nucleolus during the organism's development by following dynamic changes in fibrillarin (FIB-1) in the cells of early embryos and aged worms. This paper also illustrates the involvement of the ncl-1 gene and other possible candidate genes in nucleolar-size control. Lastly, we summarize the ribosomal proteins involved in life span and innate immunity, and those homologous genes that correspond to human disorders of ribosomopathy.

Lee, Li-Wei; Lee, Chi-Chang; Huang, Chi-Ruei; Lo, Szecheng J.

2012-01-01

19

Amoeboid Sperm of C. elegans  

NSDL National Science Digital Library

Video closeup of the C. elegans sperm that moves like an amoeba. This video is featured on the HHMI DVD, The Meaning of Sex: Genes and Gender, available free from HHMI. Also, this video is 10 seconds in length, and available in Quicktime (0.8 MB) and Windows Media (1 MB). All sex determination videos are located at: http://www.hhmi.org/biointeractive/gender/video.html.

Howard Hughes Medical Institute (Howard Hughes Medical Institute;)

2008-06-06

20

A new measurement of CP violation parameter. var epsilon. prime /. var epsilon  

SciTech Connect

The E731 experiment at Fermilab has measured the CP violation parameter Re({var epsilon}{prime}/{var epsilon}) in K{sub L,S}{yields}{pi}{pi} decay. Four decay modes were collected simultaneously to reduce systematic errors. The result is Re({var epsilon}{prime}/{var epsilon})={minus}0.0005 {plus minus} 0.0014 (stat.) {plus minus} 0.0006 (syst.), and gives no evidence for direct CP violation. 7 refs., 3 figs., 1 tab.

Yamanaka, Taku.

1990-01-01

21

Optimization of ENU mutagenesis of Caenorhabditis elegans  

Microsoft Academic Search

Chemical mutagenesis of Caenorhabditis elegans has relied primarily on EMS to produce missense mutations. The drawback of EMS mutagenesis is that the molecular lesions are primarily G\\/C ? A\\/T transitions. ENU has been shown to produce a different spectrum of mutations, but its greater toxicity to C. elegans makes it a difficult mutagen to use. We describe here methods for

Elizabeth A De Stasio; Sara Dorman

2001-01-01

22

The genetics of meiosis in Caenorhabditis elegans  

Microsoft Academic Search

The many features that have made the hermaphroditic nematode Caenorbabditis elegans a good model system for studying development have also attracted investigators to the study of meiosis. Genetic analysis suggests that in C. elegans there are two types of chromosomal sites required for proper meiotic function. The first is needed early in meiosis for recombination and segregation. The second is

Monique Zetka; Ann Rose

1995-01-01

23

Apophysomyces elegans: an Emerging Zygomycete in India  

Microsoft Academic Search

Apophysomyces elegans was considered a rare but medically important zygomycete. We analyzed the clinical records of eight patients from a single center in whom zygomycosis due to A. elegans was diagnosed over a span of 25 months. We also attempted a DNA-based method for rapid identification of the fungi and looked for interstrain polymorphism using microsattelite primers. Three patients had

A. Chakrabarti; A. Ghosh; G. S. Prasad; J. K. David; S. Gupta; A. Das; V. Sakhuja; N. K. Panda; S. K. Singh; S. Das; T. Chakrabarti

2003-01-01

24

The longevity of Caenorhabditis elegans in soil.  

PubMed

Relatively simple model organisms such as yeast, fruit-flies and the nematode, Caenorhabditis elegans, have proven to be invaluable resources in biological studies. An example is the widespread use of C. elegans to investigate the complex process of ageing. An important issue when interpreting results from these studies is the similarity of the observed C. elegans mortality pattern in the laboratory to that expected in its natural environment. We found that the longevity of C. elegans under more natural conditions is reduced up to 10-fold compared with standard laboratory culture conditions. Additionally, C. elegans mutants that live twice as long as wild-type worms in laboratory conditions typically die sooner than wild-type worms in a natural soil. These results indicate that conclusions regarding extended longevity drawn from standard laboratory assays may not extend to animals in their native environment. PMID:17148178

Van Voorhies, Wayne A; Fuchs, Jacqueline; Thomas, Stephen

2005-06-22

25

Optimum Network Var Planning by Nonlinear Programming  

Microsoft Academic Search

Controllable network VAr compensators are required in high voltage transmission networks for system loss reduction and voltage maintenance during normal and emergency operation. Long term planning of network compensators is generally based on contingencies which cause the system voltage to move out of the desired operational range. A non-linear analysis based on multi-contingency states is presented for optimum network VAr

S. S. Sachdeva; R. Billinton

1973-01-01

26

Multilevel converters as series VAr compensators  

Microsoft Academic Search

This paper presents experimental results of a multilevel converter applied as a series static VAr compensator (SVS or STATCOM). An outer feedback loop maintains the VAr operating condition and inner feedback loops equalize the DC capacitor voltages. The delta connection of the transformer secondaries provide paths for zero sequence currents to flow. The tests show its capability for operation under

Bakari Mwinyiwiwa; Zbigniew Wolanski; Boon-Teck Ooi; Yiqiang Chen

1997-01-01

27

Real-time var control by SCADA  

SciTech Connect

This paper outlines the operation and advantages of the SCADA capacitor control called CAPCON, developed by the Virginia Electric and Power Company (Virginia Power). CAPCON is used to control vars system-wide by switching substation capacitor banks based on real-time var and voltage data instead of the traditional time clock method.

Girotti, T.B.; Tweed, N.B.; Houser, N.R. (Virginia Power Co., Richmond, VA (USA))

1990-02-01

28

Macrosegregation in ESR and VAR Processes  

NASA Astrophysics Data System (ADS)

The method of heat generation, heat transfer characteristics, and ingot structure are very different in the VAR and ESR processes, which result in different tendencies and mechanisms for macrosegregation formation in forged IN-718. Freckles are niobium rich and can be generated in both ESR and VAR, with higher incidence in ESR than VAR. White spots are niobium lean and can only be found in VAR-processed materials. Freckles are indige-nous in nature, and result from the flow of solute-rich interdendritic liquid in the mushy zone during solidification. The most plausible cause for white spots is exogenous material, which remains unmelted, falling into the molten pool. The best way to minimize the formation of freckles is to improve the ingot heat transfer rate, a more difficult task in ESR than in VAR.

Yu, K. O.; Domingue, J. A.; Maurer, G. E.; Flanders, H. D.

1986-01-01

29

Prion protein in Caenorhabditis elegans  

PubMed Central

The infectious agent of prion diseases is believed to be nucleic acid-free particles composed of misfolded conformational isomers of a host protein known as prion protein (PrP). Although this “protein-only” concept is generally accepted, decades of extensive research have not been able to elucidate the mechanisms by which PrP misfolding leads to neurodegeneration and infectivity. The challenges in studying prion diseases relate in part to the limitations of mammalian prion models, which include the long incubation period post-infection until symptoms develop, the high expense of maintaining mammals for extended periods, as well as safety issues. In order to develop prion models incorporating a genetically tractable simple system with a well-defined neuronal system, we generated transgenic C. elegans expressing the mouse PrP behind the pan-neuronal ric-19 promoter (Pric-19). We show here that high expression of Pric-19::PrP in C. elegans can result in altered morphology, defective mobility and shortened lifespan. Low expression of Pric-19::PrP, however, does not cause any detectable harm. Using the dopamine neuron specific promoter Pdat-1, we also show that expression of the murine BAX, a pro-apoptotic member of the Bcl-2 family, causes dopamine neuron destruction in the nematode. However, co-expression of PrP inhibits BAX-mediated dopamine neuron degeneration, demonstrating for the first time that PrP has anti-BAX activity in living animals. Thus, these distinct PrP-transgenic C. elegans lines recapitulate a number of functional and neuropathological features of mammalian prion models and provide an opportunity for facile identification of genetic and environmental contributors to prion-associated pathology.

Park, Kyung-Won

2011-01-01

30

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.

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

2011-01-01

31

RNT-1 regulation in C. elegans.  

PubMed

RUNXs are important transcription factors, which are involved in animal development and human carcinogenesis. RNT-1, the only homologue of RUNXs, in Caenorhabditis elegans (C. elegans) has been identified and viable mutant animals of rnt-1 gene have been isolated and characterized recently. Genetic analyses using rnt-1 mutants have shown that RNT-1 is regulated by TGFbeta- and Wnt-signaling pathways in the body size regulation and male tail development. Here, we review our current understanding of RNT-1 functions in these signaling pathways. Furthermore, future prospects of RNT-1 and BRO-1 studies in C. elegans are discussed in this review. PMID:15988754

Ji, Yon Ju; Singaravelu, Gunasekaran; Ahnn, Joohong

2005-09-01

32

The sensory cilia of Caenorhabditis elegans.  

PubMed

The non-motile cilium, once believed to be a vestigial cellular structure, is now increasingly associated with the ability of a wide variety of cells and organisms to sense their chemical and physical environments. With its limited number of sensory cilia and diverse behavioral repertoire, C. elegans has emerged as a powerful experimental system for studying how cilia are formed, function, and ultimately modulate complex behaviors. Here, we discuss the biogenesis, distribution, structures, composition and general functions of C. elegans cilia. We also briefly highlight how C. elegans is being used to provide molecular insights into various human ciliopathies, including Polycystic Kidney Disease and Bardet-Biedl Syndrome. PMID:18050505

Inglis, Peter N; Ou, Guangshuo; Leroux, Michel R; Scholey, Jonathan M

2007-03-08

33

Axon regeneration mechanisms: insights from C. elegans.  

PubMed

Understanding the mechanisms of axon regeneration is of great importance to the development of therapeutic treatments for spinal cord injury or stroke. Axon regeneration has long been studied in diverse vertebrate and invertebrate models, but until recently had not been analyzed in the genetically tractable model organism Caenorhabditis elegans. The small size, simple neuroanatomy, and transparency of C. elegans allows single fluorescently labeled axons to be severed in live animals using laser microsurgery. Many neurons in C. elegans are capable of regenerative regrowth, and can in some cases re-establish functional connections. Large-scale genetic screens have begun to elucidate the genetic basis of axon regrowth. PMID:21907582

Chen, Lizhen; Chisholm, Andrew D

2011-09-08

34

Beautiful Goetzea (Goetzea elegans) Recovery Plan.  

National Technical Information Service (NTIS)

The primary objective of this recovery plan is to provide guidance for reversing the decline of Goetzea elegans and restore the species to a stable, secure, and self-sustaining condition, thereby permitting its reclassification from endangered to threaten...

1987-01-01

35

Screening Test for Neurotoxins Using 'Caenorhabditis elegans'.  

National Technical Information Service (NTIS)

A screening test was proposed for neurotoxins using a computer tracking system and Caenorhabditis elegans, a species of nematode. Simultaneous tracking of several hundred nematodes, recording their rates of locomotion and frequency of direction change wer...

D. B. Dusenbery

1987-01-01

36

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

37

Caenorhabditis elegans as an alternative animal species.  

PubMed

Caenorhabditis elegans has proven useful in toxicity testing of known toxicants, but its potential for assessing the toxicity of new pharmaceuticals is relatively unexplored. In this study the procedures used in aquatic testing of toxicants were modified to permit testing of small amounts (<40 mg) of gadolinium-based magnetic resonance imaging (MRI) compounds. Five blinded compounds were tested. The toxicity of these compounds determined using C. elegans was compared to existing mammalian test system data (minimum lethal dose [MLD] values for mice). Four of five compounds tested had the same relative sensitivity with C. elegans as with the mouse test system. Testing with C. elegans is efficient and could markedly reduce the cost of screening potentially useful compounds. PMID:11132694

Williams, P L; Anderson, G L; Johnstone, J L; Nunn, A D; Tweedle, M F; Wedeking, P

2000-12-29

38

Biomechanical Profiling of Caenorhabditis elegans Motility  

PubMed Central

Caenorhabditis elegans locomotion is a stereotyped behavior that is ideal for genetic analysis. We integrated video microscopy, image analysis algorithms, and fluid mechanics principles to describe the C. elegans swim gait. Quantification of body shapes and external hydrodynamics and model-based estimates of biomechanics reveal that mutants affecting similar biological processes exhibit related patterns of biomechanical differences. Therefore, biomechanical profiling could be useful for predicting the function of previously unstudied motility genes.

Krajacic, Predrag; Shen, Xiaoning; Purohit, Prashant K.; Arratia, Paulo; Lamitina, Todd

2012-01-01

39

Toxicity assay for deoxynivalenol using Caenorhabditis elegans  

Microsoft Academic Search

The progeny production and development rates of the nematode Caenorhabditis elegans when treated with deoxynivalenol (DON) were examined. Both purified DON and a crude extract from Fusarium graminearum cultured on rice were tested on C. elegans wild-type (Bristol N2) and a mutant strain (AU1). Significant effects (Tukey-HSD, p?

Y. Gowrinathan; J. C. Pacan; A. Hawke; T. Zhou; P. M. Sabour

2011-01-01

40

VAR Support from Distributed Wind Energy Resources.  

National Technical Information Service (NTIS)

As the size and quantity of wind farms and other distributed generation facilities increase, especially in relation to local grids, the importance of a reactive power compensator or VAR support from these facilities becomes more significant. Poorly done, ...

H. Romanowitz E. Muljadi C. P. Butterfield R. Yinger

2004-01-01

41

"Var Teatre"--A Pioneer Turns 40.  

ERIC Educational Resources Information Center

|Describes the Stockholm Municipal Youth and Children's theatre ("Var Teatre"), an institution of 14 theatres and attendant professional staff devoted exclusively to drama activities for children and teenagers. (PD)|

Jones, Pamela L.

1984-01-01

42

VAR and ESR: Do They Measure Up.  

National Technical Information Service (NTIS)

Large gun tube forgings are presently produced from statically-cast electric arc furnace steel ingots. Vacuum Arc Remelting (VAR) and Electroslag Remelting (ESR) are two secondary refining processes applied to conventionally produced steel. A comparison o...

M. E. Prengamon

1975-01-01

43

Natural variation and population genetics of Caenorhabditis elegans  

Microsoft Academic Search

C. elegans presents a low level of molecular diversity, which may be explained by its selfing mode of reproduction. Recent work on the genetic structure of natural populations of C. elegans indeed suggests a low level of outcrossing, and little geographic differentiation because of migration. The level and pattern of molecular diversity among wild isolates of C. elegans are compared

Antoine Barrière; Marie-Anne Félix

2005-01-01

44

Caenorhabditis elegans as a model for obesity research  

Microsoft Academic Search

Caenorhabditis elegans (C. elegans) is a small nematode that conserves 65% of the genes associated with human disease, has a 21-day lifespan, reproductive cycles of 3 days, large brood sizes, lives in an agar dish and does not require committee approvals for experimentation. Research using C. elegans is encouraged and a Caenorhabditis Genetics Center (CGC, Minnesota) is funded by the

J Zheng; F L Greenway

2012-01-01

45

The ecology and biodemography of Caenorhabditis elegans  

PubMed Central

The nematode Caenorhabditis elegans is a well-known model organism for research on aging and life span, but very little is known about its ecology and natural history. The strain N2 is the standard wild-type C. elegans and arose from the progeny of a single hermaphrodite. Since N2 has passed through laboratory culture, the influence of inadvertent selection and genetic drift on C. elegans strains kept in culture is unclear. Because it seems that other wild-type strains have also been subject to lengthy laboratory culture, the life span and biodemography of wild-caught C. elegans is of interest. We recovered C. elegans from snails (Helix aspersa) in ca. 50% of the California locations where we made collections. In experiments with one of the wild-caught isolates, it differed in important demographic properties, mortality, fertility, .tness, and activity patterns, from the standard N2 strain, when both strains were evaluated in a common laboratory environment. The differences were not only statistically significant; they were also large enough to be biologically important. The differences are consistent with the hypothesis that N2 has adapted to laboratory conditions.

Chen, J.; Lewis, E.E.; Carey, J.R.; Caswell, Hal; Caswell-Chen, E.P.

2008-01-01

46

Optimization of ENU mutagenesis of Caenorhabditis elegans.  

PubMed

Chemical mutagenesis of Caenorhabditis elegans has relied primarily on EMS to produce missense mutations. The drawback of EMS mutagenesis is that the molecular lesions are primarily G/C --> A/T transitions. ENU has been shown to produce a different spectrum of mutations, but its greater toxicity to C. elegans makes it a difficult mutagen to use. We describe here methods for minimizing ENU toxicity in C. elegans. Methods include preparing ENU stocks in absolute ethanol and storing stock solutions for not more than 2 weeks at -20 degrees C. To maintain reasonable brood sizes of mutagenized animals, mutagenic solutions should not exceed 1.0mM ENU. We provide data which suggest ENU is degraded or altered to more toxic products in aqueous solution, but less so in solvents such as absolute ethanol. PMID:11448645

De Stasio, E A; Dorman, S

2001-08-22

47

Biotransformation of fluorobiphenyl by Cunninghamella elegans.  

PubMed

The fungus Cunninghamella elegans is a useful model of human catabolism of xenobiotics. In this paper, the biotransformation of fluorinated biphenyls by C. elegans was investigated by analysis of the culture supernatants with a variety of analytical techniques. 4-Fluorobiphenyl was principally transformed to 4-fluoro-4'-hydroxybiphenyl, but other mono- and dihydroxylated compounds were detected in organic extracts by gas chromatography-mass spectrometry. Additionally, fluorinated water-soluble products were detected by (19)F NMR and were identified as sulphate and beta-glucuronide conjugates. Other fluorobiphenyls (2-fluoro-, 4,4'-difluoro- and 2,3,4,5,6-pentafluoro-biphenyl) were catabolised by C. elegans, yielding mono- and dihydroxylated products, but phase II metabolites were detected from 4,4'-difluorobiphenyl only. PMID:19956946

Amadio, Jessica; Murphy, Cormac D

2009-12-03

48

A sleep state during C. elegans development.  

PubMed

Caenorhabditis elegans is the simplest animal shown to sleep. It sleeps during lethargus, a larval transition stage. Behavior during lethargus has the sleep properties of a specific quiescent posture and elevated arousal threshold that are reversible to strong stimulation and of increased sleep drive following sleep deprivation. Genetic similarities between sleep regulation during C. elegans lethargus and sleep regulation in other animals point to a sleep state that was an evolutionarily ancestor to sleep both in C. elegans and other animals. Recent publications have shed light on key questions in sleep biology: First, How is sleep regulated? Second, How is sensory information gated during sleep? Third, How is sleep homeostasis mediated? Fourth, What is the core function of sleep? PMID:23562486

Nelson, Matthew D; Raizen, David M

2013-04-03

49

Metabolism of naphthalene by Cunninghamella elegans.  

PubMed Central

Cunninghamella elegans grown on Sabouraud dextrose broth in the presence of naphthalene produced six metabolites. Each product was isolated and identified by conventional chemical techniques. The major metabolites were 1-naphthol (67.9%) and 4-hydroxy-1-tetralone (16.7%). Minor products isolated were 1,4-naphthoquinone (2.8%), 1,2-naphthoquinone (0.2%), 2-naphthol (6.3%), and trans-1,2-dihydroxy-1,2-dihydronaphthalene (5.3%). C. elegans oxidized both 1-naphthol and 1,4-naphthoquinone to 4-hydroxy-1-tetralone. The results suggest that C. elegans oxidizes naphthalene by a sequence of reactions similar to those reported for the mammalian metabolism of this hydrocarbon.

Cerniglia, C E; Gibson, D T

1977-01-01

50

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.

Hou, Aixin

2013-01-01

51

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.

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

1993-01-01

52

C. elegans survivors without telomerase  

PubMed Central

In most eukaryotic organisms with a linear genome, the telomerase complex is essential for telomere maintenance and, thus, for genomic integrity. Proper telomerase function in stem and germ cell populations counteracts replication-dependent telomere shortening. On the other hand, repression of telomerase expression in most somatic tissues limits the proliferative potential of these cells through the induction of a permanent cell cycle arrest termed senescence upon critical telomere erosion. Thus, senescence, induced by telomere shortening and subsequent DNA damage signaling, is an essential tumor suppressive mechanism, emphasized by the fact that repression of telomerase is lost in about 90% of cancers, endowing them with unlimited proliferative potential. In 10% of cancers telomeres are maintained using the recombination-based alternative mechanism of telomere lengthening (ALT). To date, ALT and ALT-like mechanisms have only been described in the context of individual cells such as cancer cells and yeast. Now, several “survivor” strains of the nematode Caenorhabditis elegans have been generated that can propagate despite mutations of the telomerase gene. These nematode strains represent the first multi-cellular organism with canonical telomerase that can survive in the absence of a functional telomerase pathway.

Lackner, Daniel H.; Karlseder, Jan

2013-01-01

53

Implications of Dynamic Factor Models for VAR Analysis  

Microsoft Academic Search

This paper considers VAR models incorporating many time series that interact through a few dynamic factors. Several econometric issues are addressed including estimation of the number of dynamic factors and tests for the factor restrictions imposed on the VAR. Structural VAR identification based on timing restrictions, long run restrictions, and restrictions on factor loadings are discussed and practical computational methods

James H. Stock; Mark W. Watson

2005-01-01

54

Power electronics in electric utilities: Static var compensators  

Microsoft Academic Search

This paper deals with dynamic var compensation of electric power systems, applying power electronics for reactive power generation and control. After an overview of the emergence and status of modern, solid-state var compensators in utility and industrial applications, the first part of the paper explains how dynamic var compensation increases transmittable power by providing voltage support, transient stability improvement, and

L. Gyugyi

1988-01-01

55

Evaluation of the hepatoprotective and antioxidant activity of Boehmeria nivea var. nivea and B. nivea var. tenacissima  

Microsoft Academic Search

In this study, the relationship between liver protective effects and antioxidant activity of Boehmeria nivea var. nivea (=B. nivea) and B. nivea var. tenacissima (=B. frutescens) was investigated. The water extracts of both plants exhibited a hepatoprotective activity against CCl4-induced liver injury. B. nivea var. nivea and B. nivea var. tenacissima, also showed anti-oxidant effects in FeCl2-ascorbate induced lipid peroxidation

Chun-Ching Lin; Ming-Hong Yen; Tsae-shiuan Lo; Jer-Min Lin

1998-01-01

56

Ascaroside signaling in C. elegans*  

PubMed Central

Over the past 10 years, the relevance of small-molecule signaling for many aspects of C. elegans development and behavior has become apparent. One prominent group of small-molecule signals are the ascarosides, which control dauer entry and exit as well as a variety of sex-specific and social behaviors, including male attraction, hermaphrodite repulsion, olfactory plasticity, and aggregation. This wide range of biological functions is facilitated by a great diversity of ascaroside chemical structures. These are based on the sugar ascarylose, which is linked to fatty acid-like side chains of varying lengths and often decorated further with building blocks derived from amino acids, folate, and other primary metabolites. Different ascarosides or combinations of ascarosides mediate different phenotypes, and even small differences in chemical structures are often associated with strongly altered activity profiles. Additional complexity arises from concentration-dependent effects and synergism between different ascarosides. The ascarosides are sensed by several types of chemosensory head neurons, including the ASK, ASI, and ADL neurons as well as the male-specific CEM neurons. Ascaroside perception is mediated by diverse families of G-protein coupled membrane receptors that act upstream of conserved signal transduction pathways, including insulin/IGF-1 signaling and transforming growth factor beta (TGF-?) signaling. Biosynthesis of the ascarosides appears to integrate input from several primary metabolic pathways, including peroxisomal ?-oxidation of long-chain fatty acids and amino acid catabolism. Life stage, sex, as well as food availability and other environmental factors affect ascaroside biosynthesis, suggesting that ascaroside signaling communicates detailed information about life history and metabolic state.

Ludewig, Andreas H.; Schroeder, Frank C.

2013-01-01

57

Large scale voltage stability constrained optimal VAr planning and voltage stability applications using existing OPF\\/optimal VAr planning tools  

Microsoft Academic Search

Traditionally in optimal VAr planning, the feasible operation has been translated as observing voltage profile criteria ensuring that the system voltage profile is acceptable for system normal and post contingency conditions. This feasibility definition is not sufficient when considering the VAr planning practice of the utilities concerned with voltage stability problems. Presently, these utilities use two reinforcement criteria for VAr

Ebrahim Vaahedi; J. Tamby; Y. Mansour; Wenyuan Li; D. Sun

1999-01-01

58

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

59

The mevalonate pathway in C. Elegans  

PubMed Central

The mevalonate pathway in human is responsible for the synthesis of cholesterol and other important biomolecules such as coenzyme Q, dolichols and isoprenoids. These molecules are required in the cell for functions ranging from signaling to membrane integrity, protein prenylation and glycosylation, and energy homeostasis. The pathway consists of a main trunk followed by sub-branches that synthesize the different biomolecules. The majority of our knowledge about the mevalonate pathway is currently focused on the cholesterol synthesis branch, which is the target of the cholesterol-lowering statins; less is known about the function and regulation of the non-cholesterol-related branches. To study them, we need a biological system where it is possible to specifically modulate these metabolic branches individually or in groups. The nematode Caenorhabditis elegans (C. elegans) is a promising model to study these non-cholesterol branches since its mevalonate pathway seems very well conserved with that in human except that it has no cholesterol synthesis branch. The simple genetic makeup and tractability of C. elegans makes it relatively easy to identify and manipulate key genetic components of the mevalonate pathway, and to evaluate the consequences of tampering with their activity. This general experimental approach should lead to new insights into the physiological roles of the non-cholesterol part of the mevalonate pathway. This review will focus on the current knowledge related to the mevalonate pathway in C. elegans and its possible applications as a model organism to study the non-cholesterol functions of this pathway.

2011-01-01

60

Comparative toxicology of mercurials in Caenorhabditis elegans.  

PubMed

Mercury (Hg) is a toxic metal that can exist in multiple chemical species. Humans are commonly exposed to methylmercury and Hg vapor, which are converted to mercuric species in the body. Despite years of research, little information exists on the similarities and differences in the mechanisms of Hg toxicity. The relative toxicity of mercuric chloride (HgCl(2)) and methylmercury chloride (MeHgCl) in Caenorhabditis elegans was determined in assays that measured growth, feeding, reproduction, and locomotion. The effect of HgCl(2) 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 in terms of C. elegans growth. However, MeHgCl was more toxic to C. elegans than HgCl(2) 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 HgCl(2). In general, MeHgCl was more toxic to C. elegans than HgCl(2), particularly when assaying behaviors that require neuromuscular function. PMID:21692103

McElwee, Matthew K; Freedman, Jonathan H

2011-07-11

61

The neurexin superfamily of Caenorhabditis elegans  

Microsoft Academic Search

The neurexin superfamily is a group of transmembrane molecules mediating cell–cell contacts and generating specialized membranous domains in polarized epithelial and nerves cells. We describe here the domain organization and expression of the entire, core neurexin superfamily in the nematode Caenorhabditis elegans, which is composed of three family members. One of the superfamily members, nrx-1, is an ortholog of vertebrate

Liat Haklai-Topper; Jürgen Soutschek; Helena Sabanay; Jochen Scheel; Oliver Hobert; Elior Peles

2011-01-01

62

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

63

Metabolism in the Caenorhabditis elegans Mit mutants  

Microsoft Academic Search

In many eukaryotes oxidative phosphorylation via the mitochondrial electron transport chain provides the major means of ATP production. Complete removal of this capacity often results in premature death. Recent studies using the nematode Caenorhabditis elegans are surprising because they have revealed that disruption of many of the key components of the normal mitochondrial energy-generating machinery do not result in death,

Shane L. Rea

2005-01-01

64

CAENORHABDITIS ELEGANS AS AN ALTERNATIVE ANIMAL SPECIES  

Microsoft Academic Search

Caenorhabditis elegans has proven useful in toxicity testing of known toxicants, but its potential for assessing the toxicity of new pharmaceuticals is relatively unexplored. In this study the procedures used in aquatic testing of toxicants were modified to permit testing of small amounts (<40 mg) of gadolinium-based magnetic resonance imaging (MRI) compounds. Five blinded compounds were tested. The toxicity of

Phillip L. Williams; Gary L. Anderson; John L. Johnstone; Adrian D. Nunn; Michael F. Tweedle; Paul Wedeking

2000-01-01

65

Xenobiotic Detoxification in the Nematode Caenorhabditis elegans  

PubMed Central

The nematode Caenorhabditis elegans is an important model organism for the study of such diverse aspects of animal physiology and behavior as embryonic development, chemoreception, and the genetic control of lifespan. Yet, even though the entire genome sequence of this organism was deposited into public databases several years ago, little is known about xenobiotic metabolism in C. elegans. In part, the paucity of detoxification information may be due to the plush life enjoyed by nematodes raised in the laboratory. In the wild, however, these animals experience a much greater array of chemical assaults. Living in the interstitial water of the soil, populations of C. elegans exhibit a boom and bust lifestyle characterized by prodigious predation of soil microbes punctuated by periods of dispersal as a non-developing alternative larval stage. During the booming periods of population expansion, these animals almost indiscriminately consume everything in their environment including any number of compounds from other animals, microorganisms, plants, and xenobiotics. Several recent studies have identified many genes encoding sensors and enzymes these nematodes may use in their xeno-coping strategies. Here, we will discuss these recent advances, as well as the efforts by our lab and others to utilize the genomic resources of the C. elegans system to elucidate this nematode’s molecular defenses against toxins.

Lindblom, Tim H.; Dodd, Allyn K.

2009-01-01

66

Neurogenetics of vesicular transporters in C. elegans  

Microsoft Academic Search

The nematode Caenorhabditis elegans has a number of advantages for the analysis of synaptic molecules. These include a simple nervous system in which all cells are identified and synaptic connectivity is known and reproducible, a large collection of mutants and powerful methods of genetic analysis, simple methods for the generation and analysis of transgenic animals, and a number of relatively

JAMES B. RAND; JANET S. DUERR; DENNIS L. FRISBY

2000-01-01

67

Cytological Analysis of Meiosis in Caenorhabditis elegans  

PubMed Central

The nematode Caenorhabditis elegans has emerged as an informative experimental system for analysis of meiosis, in large part because of the advantageous physical organization of meiotic nuclei as a gradient of stages within the germline. Here we provide tools for detailed observational studies of cells within the worm gonad, including techniques for light and electron microscopy.

Phillips, Carolyn M.; McDonald, Kent L.; Dernburg, Abby F.

2011-01-01

68

Taurine reduces ER stress in C. elegans  

PubMed Central

Background ER stress is a strong indicator of whether or not a cell is undergoing physiological stress. C. elegans is a practical system of characterizing the effect of ER stress at the in vivo or organismal level. Methods This study characterized taurine’s anti-ER stress potential employing western blotting on ER stress markers and assays of motility, lifespan comparison, and fecundity measurement. Results When treated with tunicamycin, C. elegans showed the typical ER stress symptoms. It showed a higher expression of hsp-70 and skn-1 than the non-treated control. Survivorship significantly decreased under tunicamycin treatment, and the offspring number also decreased. During the synchronized culture under ER stress conditions, the C. elegans showed early signs of aging especially between L3 and L4 within their life span, along with lowered motility. The worms, however, showed a positive response to the taurine treatment under ER stress conditions. Conclusions When C. elegans were treated with taurine before or after the tunicamycin treatment, they showed a less severe level of ER stress, including an enhanced survivorship, increased motility, and augmented fecundity. Taken together, these results strongly indicate that taurine works positively to cope with ER stress from the organismal perspective.

2010-01-01

69

Static var compensators stabilize power voltages  

SciTech Connect

This article discusses the operation of a static var compensator as installed by Alabama Power near a steel mill with a large arc furnace load. This is expected to result in a number of benefits, including flicker reduction, dynamic power factor correction, harmonics filtering and a reduction in system losses.

Burch, R.

1996-06-01

70

Saponins from Furcraea selloa var. marginata.  

PubMed

Four steroidal saponins were isolated from the leaves of Furcraea selloa var. marginata. These included one furostanol saponin, furcreafurostatin (1), and three known spirostanol saponins, furcreastatin (3), yuccaloeside C (4) and cantalasaponin-1 (5). The 22-O-methyl ether (2) of furcreafurostatin (1) was also characterized. The structures were determined by using a combination of spectroscopic techniques. PMID:15567237

Simmons-Boyce, Joanne L; Tinto, Winston F; McLean, Stewart; Reynolds, William F

2004-12-01

71

Triterpenoids from Aglaia odorata var. microphyllina.  

PubMed

Five new apotirucallane-type triterpenoids (1-5), named agladorals A-E, and 28 known compounds (20 triterpenoids and 8 rocaglamides) were isolated from the twigs of Aglaia odorata var. microphyllina. Their structures were elucidated by spectroscopic analysis. PMID:23046464

Liu, Jia; Yang, Sheng-Ping; Ni, Gang; Gu, Yu-Cheng; Yue, Jian-Min

2012-01-01

72

Characterization of the C. elegans erlin homologue  

PubMed Central

Background Erlins are highly conserved proteins associated with lipid rafts within the endoplasmic reticulum (ER). Biochemical studies in mammalian cell lines have shown that erlins are required for ER associated protein degradation (ERAD) of activated inositol-1,4,5-trisphosphate receptors (IP3Rs), implying that erlin proteins might negatively regulate IP3R signalling. In humans, loss of erlin function appears to cause progressive intellectual disability, motor dysfunction and joint contractures. However, it is unknown if defects in IP3R ERAD are the underlying cause of this disease phenotype, whether ERAD of activated IP3Rs is the only function of erlin proteins, and what role ERAD plays in regulating IP3R-dependent processes in the context of an intact animal or embryo. In this study, we characterize the erlin homologue of the nematode Caenorhabditis elegans and examine erlin function in vivo. We specifically set out to test whether C. elegans erlin modulates IP3R-dependent processes, such as egg laying, embryonic development and defecation rates. We also explore the possibility that erlin might play a more general role in the ERAD pathway of C. elegans. Results We first show that the C. elegans erlin homologue, ERL-1, is highly similar to mammalian erlins with respect to amino acid sequence, domain structure, biochemical properties and subcellular location. ERL-1 is present throughout the C. elegans embryo; in adult worms, ERL-1 appears restricted to the germline. The expression pattern of ERL-1 thus only partially overlaps with that of ITR-1, eliminating the possibility of ERL-1 being a ubiquitous and necessary regulator of ITR-1. We show that loss of ERL-1 does not affect overall phenotype, or alter brood size, embryonic development or defecation cycle length in either wild type or sensitized itr-1 mutant animals. Moreover we show that ERL-1 deficient worms respond normally to ER stress conditions, suggesting that ERL-1 is not an essential component of the general ERAD pathway. Conclusions Although loss of erlin function apparently causes a strong phenotype in humans, no such effect is seen in C. elegans. C. elegans erlin does not appear to be a ubiquitous major modulator of IP3 receptor activity nor does erlin appear to play a major role in ERAD.

2012-01-01

73

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.

Helmcke, Kirsten J.; Aschner, Michael

2010-01-01

74

Hormetic effect of methylmercury on Caenorhabditis elegans.  

PubMed

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

2010-08-05

75

The embryonic muscle transcriptome of Caenorhabditis elegans  

PubMed Central

Background The force generating mechanism of muscle is evolutionarily ancient; the fundamental structural and functional components of the sarcomere are common to motile animals throughout phylogeny. Recent evidence suggests that the transcription factors that regulate muscle development are also conserved. Thus, a comprehensive description of muscle gene expression in a simple model organism should define a basic muscle transcriptome that is also found in animals with more complex body plans. To this end, we applied microarray profiling of Caenorhabtidis elegans cells (MAPCeL) to muscle cell populations extracted from developing C. elegans embryos. Results We used fluorescence-activated cell sorting to isolate myo-3::green fluorescent protein (GFP) positive muscle cells, and their cultured derivatives, from dissociated early C. elegans embryos. Microarray analysis identified 7,070 expressed genes, 1,312 of which are enriched in the myo-3::GFP positive cell population relative to the average embryonic cell. The muscle enriched gene set was validated by comparisons with known muscle markers, independently derived expression data, and GFP reporters in transgenic strains. These results confirm the utility of MAPCeL for cell type specific expression profiling and reveal that 60% of these transcripts have human homologs. Conclusion This study provides a comprehensive description of gene expression in developing C. elegans embryonic muscle cells. The finding that more than half of these muscle enriched transcripts encode proteins with human homologs suggests that mutant analysis of these genes in C. elegans could reveal evolutionarily conserved models of muscle gene function, with ready application to human muscle pathologies.

Fox, Rebecca M; Watson, Joseph D; Von Stetina, Stephen E; McDermott, Joan; Brodigan, Thomas M; Fukushige, Tetsunari; Krause, Michael; Miller, David M

2007-01-01

76

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

77

Ethanol targets: a BK channel cocktail in C. elegans.  

PubMed

A genetic screen for resistance to ethanol intoxication in Caenorhabditis elegans isolated mutants of the gene slo-1. slo-1 encodes the pore-forming subunit of a large-conductance Ca(2+)-activated K(+) channel previously shown to limit excitatory neurotransmitter release in C. elegans. Electrophysiological data recorded in vivo are consistent with a model in which ethanol potentiation of SLO-1 produces intoxication in C. elegans by reducing excitatory neurotransmitter release. PMID:15374666

Crowder, C Michael

2004-10-01

78

Chemical detoxification of small molecules by Caenorhabditis elegans.  

PubMed

Caenorhabditis elegans lives in compost and decaying fruit, eats bacteria and is exposed to pathogenic microbes. We show that C. elegans is able to modify diverse microbial small-molecule toxins via both O- and N-glucosylation as well as unusual 3'-O-phosphorylation of the resulting glucosides. The resulting glucosylated derivatives have significantly reduced toxicity to C. elegans, suggesting that these chemical modifications represent a general mechanism for worms to detoxify their environments. PMID:23163740

Stupp, Gregory S; von Reuss, Stephan H; Izrayelit, Yevgeniy; Ajredini, Ramadan; Schroeder, Frank C; Edison, Arthur S

2012-11-26

79

Evaluation of the hepatoprotective and antioxidant activity of Boehmeria nivea var. nivea and B. nivea var. tenacissima.  

PubMed

In this study, the relationship between liver protective effects and antioxidant activity of Boehmeria nivea var. nivea (= B. nivea) and B. nivea var. tenacissima (= B. frutescens) was investigated. The water extracts of both plants exhibited a hepatoprotective activity against CCl4-induced liver injury. B. nivea var. nivea and B. nivea var. tenacissima, also showed anti-oxidant effects in FeCl2-ascorbate induced lipid peroxidation in rat liver homogenate. Moreover, the active oxygen species scavenging potencies were evaluated by an electron spin resonance (ESR) spin-trapping technique. B. nivea var. tenacissima displayed better superoxide radical scavenging activity than B. nivea. Based on these findings, we suggest that in the liver protective and antioxidative effects of B. nivea var. nivea and B. nivea var. tenacissima, possibly involve mechanisms related to free radical scavenging effects. PMID:9533427

Lin, C C; Yen, M H; Lo, T S; Lin, J M

1998-02-01

80

Embryological Studies on Narcissus tazetta var. chinensis  

Microsoft Academic Search

Chinese narcissus (Narcissus tazetta var. chinensis Roem) blooms but has no seeds. Embryological studies on the species were conducted to discover the causes of its sterility.\\u000a Its anther wall is composed of four layers of cells, and its tapetum is of the secretory type. The cytokinesis of microspore\\u000a mother cells is of the successive type, and the tetrad is tetrahedral.

Lili Ge; Jian Wu; Linjiao Chen; Rui Wang; Huiqiao Tian

2006-01-01

81

Iridoid glucosides from Veronica pectinata var. glandulosa.  

PubMed

A new highly oxygenated iridoid glucoside, urphoside B (1) was isolated from the Veronica pectinata var. glandulosa together with seven known iridoid glucosides, aucubin, catalpol, veronicoside, catalposide, verproside, amphicoside and 6-O-veratroyl catalpol. The planar as well as the stereo structures of the isolated compounds were determined by means of extensive 1D- and 2D-NMR spectroscopy and confirmed by HR-Mass. PMID:12939031

Harput, U Sebnem; Nagatsu, Akito; Ogihara, Yukio; Saracoglu, Iclal

82

Caenorhabditis elegans innexins regulate active zone differentiation.  

PubMed

In a genetic screen for active zone defective mutants in Caenorhabditis elegans, we isolated a loss-of-function allele of unc-7, a gene encoding an innexin/pannexin family gap junction protein. Innexin UNC-7 regulates the size and distribution of active zones at C. elegans neuromuscular junctions. Loss-of-function mutations in another innexin, UNC-9, cause similar active zone defects as unc-7 mutants. In addition to presumptive gap junction localizations, both UNC-7 and UNC-9 are also localized perisynaptically throughout development and required in presynaptic neurons to regulate active zone differentiation. Our mosaic analyses, electron microscopy, as well as expression studies suggest a novel and likely nonjunctional role of specific innexins in active zone differentiation in addition to gap junction formations. PMID:19386917

Yeh, Edward; Kawano, Taizo; Ng, Sharon; Fetter, Richard; Hung, Wesley; Wang, Ying; Zhen, Mei

2009-04-22

83

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."

84

Locomotion of C elegans in structured environments  

NASA Astrophysics Data System (ADS)

We have established a combined experimental and numerical platform to study the swimming dynamics of an undulating worm in structured environments (fluid-filled micro-pillar arrays). We have shown that the worm (C. elegans) swims with different velocity and frequency depending on the lattice spacing and our purely mechanistic simulations (elastically linked bead-chain) reproduce the experimental results qualitatively and quantitatively, including ``life-like'' trajectories the worm exhibits. We build upon this platform to investigate more complex environments, such as linear and radial lattices, with gradients in spacing. In addition, we study C. elegans mutants to investigate the role of length of the worm, frequency of undulations, and mechano-sensation on the resultant dynamics. We also examine the worm moving through a lattice with random distribution of obstacles - a model soil-like environment. Our combined experimental and simulations approach allows us to gain insights into the dynamics of locomotion of undulating microorganisms in realistic complex environments.

Majmudar, Trushant; Keaveny, Eric; Shelley, Michael; Zhang, Jun

2011-11-01

85

C. elegans for anti-infective discovery.  

PubMed

Widespread use of antimicrobial agents has led to the emergence of multidrug resistant pathogens, which are becoming increasingly common in clinical practice. This underscores the need to discover novel anti-infective compounds. The soil-living nematode Caenorhabditis elegans has proved to be an excellent model host in the search for such compounds. Indeed, this alternative host is successfully being used to identify traditional microbicidal agents, including antihelminthic compounds, as well as novel agents that attenuate microbial virulence or enhance the host's immune response. Thanks to numerous advantageous features, including its amenability to high-throughput automated screens that allow for the detection of bioactive products among thousands of tested substances, the C. elegans model is now in the spotlight of scientific attention. PMID:23993686

Arvanitis, Marios; Glavis-Bloom, Justin; Mylonakis, Eleftherios

2013-08-29

86

Caenorhabditis elegans Pheromones Regulate Multiple Complex Behaviors  

PubMed Central

Summary of recent advances A family of small molecules called ascarosides act as pheromones to control multiple behaviors in the nematode Caenorhabditis elegans. At picomolar concentrations, a synergistic mixture of at least three ascarosides produced by hermaphrodites causes male-specific attraction. At higher concentrations, the same ascarosides, perhaps in a different mixture, induce the developmentally arrested stage known as dauer. The production of ascarosides is strongly dependent on environmental conditions, although relatively little is known about the major variables and mechanisms of their regulation. Thus, male mating and dauer formation are linked through a common set of small molecules whose expression is sensitive to a given microenvironment, suggesting a model by which ascarosides regulate the overall life cycle of C. elegans.

Edison, Arthur S.

2009-01-01

87

Embryonic Cell Division in C. elegans  

NSDL National Science Digital Library

Time-lapse microscopy showing cell division from 1 to 2 to 4 cell stages in C. elegans with fluorescent chromosomes. This video is featured on the HHMI DVD, The Meaning of Sex: Genes and Gender, available free from HHMI. Also, this video is 1 minute and 30 seconds in length, and available in Quicktime(3 MB) and Windows Media (4 MB). All sex determination videos are located at: http://www.hhmi.org/biointeractive/gender/video.html.

Howard Hughes Medical Institute (HHMI;)

2008-06-06

88

A global analysis of Caenorhabditis elegans operons  

Microsoft Academic Search

The nematode worm Caenorhabditis elegans and its relatives are unique among animals in having operons. Operons are regulated multigene transcription units, in which polycistronic pre-messenger RNA (pre-mRNA coding for multiple peptides) is processed to monocistronic mRNAs. This occurs by 3' end formation and trans-splicing using the specialized SL2 small nuclear ribonucleoprotein particle for downstream mRNAs. Previously, the correlation between downstream

Thomas Blumenthal; Donald Evans; Christopher D. Link; Alessandro Guffanti; Daniel Lawson; Jean Thierry-Mieg; Danielle Thierry-Mieg; Wei Lu Chiu; Kyle Duke; Moni Kiraly; Stuart K. Kim

2002-01-01

89

Extrachromosomal DNA Transformation ofCaenorhabditis elegans  

Microsoft Academic Search

arrayswere extrachromosomal and heritable. On average50% oftheprogenyofa transformed hermaphrodite still carried theexogenous sequences.Insitu hybridization experiments demonstrated thatapproximately half of'the transformed animals carried foreign DNA inalloftheir cells; theremainder weremosaic animals inwhichsomecells contained the exogenoussequenceswhile others carried no detectable foreign DNA.Thepresenceofmosaic'and nonmosaic nematodes intransformed populations may permit detailed analysis oftheexpression andfunction ofe.elegans genes. anddevelopmental physiology ofthenematode. Herewe describe theintroduction offoreign DNA into

DAN T. STINCHCOMB; JOCELYN E. SHAW; STEPHEN H. CARR; DAVID HIRSH

1985-01-01

90

Fungal biotransformation of mosapride by Cunninghamella elegans  

Microsoft Academic Search

The filamentous fungus, Cunninghamella elegans AS 3.156, was used as a microbial model of mammalian metabolism to transform mosapride, a selective 5-HT4-receptor agonist. The fungal metabolites of mosapride were separated and detected by ultra performance liquid chromatography–tandem mass spectrometric method. After incubation for 120h, the parent drug was metabolized to thirteen metabolites, one of which was known major mammalian metabolite,

Xiao-Hong Sun; Feng Man; Li-Yan Pang; Gui-Hua Gao; Xiao-Qin Li; Xiu-Lan Qi; Fa-Mei Li

2009-01-01

91

RNAi pathway integration in Caenorhabditis elegans development  

Microsoft Academic Search

In this review, the pathways involving small RNAs are provided followed by a new and updated network that illustrates their\\u000a interplay with diverse cellular mechanisms in Caenorhabditis elegans. The RNA silencing pathways are now recognized as key factors that connect together the many variations in biological processes,\\u000a including transcriptional gene regulation, post-transcriptional gene silencing, translational gene silencing, apoptosis, meiosis,\\u000a and

Sadegh Azimzadeh Jamalkandi; Ali Masoudi-Nejad

92

Caenorhabditis Elegans--Applications to Nematode Genomics  

PubMed Central

The complete genome sequence of the free-living nematode Caenorhabditis elegans was published 4 years ago. Since then, we have seen great strides in technologies that seek to exploit this data. Here we describe the application of some of these techniques and other advances that are helping us to understand about not only the biology of this important model organism but also the entire phylum Nematoda.

Parkinson, John

2003-01-01

93

State-dependency in C. elegans.  

PubMed

Memory and the expression of learned behaviors by an organism are often triggered by contextual cues that resemble those that were present when the initial learning occurred. In state-dependent learning, the cue eliciting a learned behavior is a neuroactive drug; behaviors initially learned during exposure to centrally acting compounds such as ethanol are subsequently recalled better if the drug stimulus is again present during testing. Although state-dependent learning is well documented in many vertebrate systems, the molecular mechanisms underlying state-dependent learning and other forms of contextual learning are not understood. Here we demonstrate and present a genetic analysis of state- dependent adaptation in Caenorhabditis elegans. C. elegans normally exhibits adaptation, or reduced behavioral response, to an olfactory stimulus after prior exposure to the stimulus. If the adaptation to the olfactory stimulus is acquired during ethanol administration, the adaptation is subsequently displayed only if the ethanol stimulus is again present. cat-1 and cat-2 mutant animals are defective in dopaminergic neuron signaling and are impaired in state dependency, indicating that dopamine functions in state-dependent adaptation in C. elegans. PMID:15344920

Bettinger, J C; McIntire, S L

2004-10-01

94

Developmental genetics of Caenorhabditis elegans sex determination.  

PubMed

The nematode Caenorhabditis elegans has two naturally occurring sexes: a self-fertile XX hermaphrodite that first produces sperm, then oocytes, and an XO male. The primary determinant of sex is the X:A ratio, the number of X chromosomes to sets of autosomes. The X:A ratio regulates not only sex determination, but also dosage compensation. In the intervening years since the identification of the X:A ratio, most of the key regulatory genes that respond to the X:A ratio have been genetically identified and ordered into regulatory hierarchies. Advances have also been made in identifying the X chromosome numerator elements of the X:A ratio. This review highlights the genetic, molecular, and biochemical approaches that have led to an understanding of how these genes interact to control sex determination and dosage compensation. The review also discusses the differences between the control of sexual cell fate in the soma and germ line of C. elegans and addresses the role of germ-line-specific regulation in controlling the sperm-oocyte decision in the hermaphrodite germ line. Finally, strategies that take advantage of the availability of the entire C. elegans genome sequence, which is expected to be completed in 1998, are discussed for identifying hitherto unidentified genes that may play a role in the control of sexual cell fate. PMID:9784974

Kuwabara, P E

1999-01-01

95

Polygenic control of Caenorhabditis elegans fat storage.  

PubMed

Tubby mice and individuals with Bardet-Biedl syndrome have defects in ciliated neuron function and obesity, suggesting an as-yet unknown metabolic signaling axis from ciliated neurons to fat storage tissues. Here we show coordinate regulation of Caenorhabditis elegans fat storage by orthologues of these genes acting in ciliated neurons and by a 3-ketoacyl-coA thiolase (encoded by kat-1) that acts in fat storage tissue. A genetic screen for markedly enhanced fat storage in tub-1 mutants led to the isolation only of kat-1 alleles, which impair fatty acid beta-oxidation. kat-1 acts in the intestine, the major C. elegans fat storage tissue, and is transcriptionally upregulated in animals with high fat storage. A genetic screen for synergistic increase in fat storage of a kat-1 mutant identified bbs-1. bbs-1 acts in 15 ciliated neurons that are poised to sense external and internal nutrient levels, supporting a model in which bbs-1 and tub-1 in ciliated neurons form part of an ancient, conserved neuroendocrine axis. This pathway also includes genes encoding intraflagellar transport proteins and cyclic nucleotide gated channels, demonstrating that C. elegans fat storage is under polygenic control. PMID:16462744

Mak, Ho Yi; Nelson, Laura S; Basson, Michael; Johnson, Carl D; Ruvkun, Gary

2006-02-05

96

CLC chloride channels in Caenorhabditis elegans.  

PubMed

The genome of the nematode Caenorhabditis elegans encodes six putative chloride channels (CeCLC-1 through CeCLC-6) that represent all three known branches of the mammalian CLC gene family. Using promoter fragments to drive the expression of the green fluorescent protein, CeCLC-2, -3, and -4 expression was studied in transgenic C. elegans. CeCLC-4 was specifically expressed in the large H-shaped excretory cell, where it was co-expressed with CeCLC-3, which is also expressed in other cells, including neurons, muscles, and epithelial cells. Also, CeCLC-2 was expressed in several cells of the nervous system, intestinal cells, and vulval muscle cells. Similar to mammalian CLC proteins, only two nematode CLC channels elicited detectable plasma membrane currents in Xenopus oocytes. CeCLC-3 currents were inwardly rectifying and were activated by positive prepulses. Its complex gating behavior can be explained by two gates, at least one of which depends on extracellular anions. In this respect it resembles some mammalian chloride channels with which it also shares a preference of chloride over iodide. C. elegans thus provides new opportunities to understand common mechanisms underlying structure and function in CLC channels and will allow for a genetic dissection of chloride channels in this simple model organism. PMID:10567397

Schriever, A M; Friedrich, T; Pusch, M; Jentsch, T J

1999-11-26

97

Acute carbon dioxide avoidance in Caenorhabditis elegans.  

PubMed

Carbon dioxide is produced as a by-product of cellular respiration by all aerobic organisms and thus serves for many animals as an important indicator of food, mates, and predators. However, whether free-living terrestrial nematodes such as Caenorhabditis elegans respond to CO2 was unclear. We have demonstrated that adult C. elegans display an acute avoidance response upon exposure to CO2 that is characterized by the cessation of forward movement and the rapid initiation of backward movement. This response is mediated by a cGMP signaling pathway that includes the cGMP-gated heteromeric channel TAX-2/TAX-4. CO2 avoidance is modulated by multiple signaling molecules, including the neuropeptide Y receptor NPR-1 and the calcineurin subunits TAX-6 and CNB-1. Nutritional status also modulates CO2 responsiveness via the insulin and TGFbeta signaling pathways. CO2 response is mediated by a neural circuit that includes the BAG neurons, a pair of sensory neurons of previously unknown function. TAX-2/TAX-4 function in the BAG neurons to mediate acute CO2 avoidance. Our results demonstrate that C. elegans senses and responds to CO2 using multiple signaling pathways and a neural network that includes the BAG neurons and that this response is modulated by the physiological state of the worm. PMID:18524955

Hallem, Elissa A; Sternberg, Paul W

2008-06-04

98

Detoxification of Benzoxazolinone Allelochemicals from Wheat by Gaeumannomyces graminis var. tritici, G. graminis var. graminis, G. graminis var. avenae, and Fusarium culmorum  

PubMed Central

The ability of phytopathogenic fungi to overcome the chemical defense barriers of their host plants is of great importance for fungal pathogenicity. We studied the role of cyclic hydroxamic acids and their related benzoxazolinones in plant interactions with pathogenic fungi. We identified species-dependent differences in the abilities of Gaeumannomyces graminis var. tritici, Gaeumannomyces graminis var. graminis, Gaeumannomyces graminis var. avenae, and Fusarium culmorum to detoxify these allelochemicals of gramineous plants. The G. graminis var. graminis isolate degraded benzoxazolin-2(3H)-one (BOA) and 6-methoxy-benzoxazolin-2(3H)-one (MBOA) more efficiently than did G. graminis var. tritici and G. graminis var. avenae. F. culmorum degraded BOA but not MBOA. N-(2-Hydroxyphenyl)-malonamic acid and N-(2-hydroxy-4-methoxyphenyl)-malonamic acid were the primary G. graminis var. graminis and G. graminis var. tritici metabolites of BOA and MBOA, respectively, as well as of the related cyclic hydroxamic acids. 2-Amino-3H-phenoxazin-3-one was identified as an additional G. graminis var. tritici metabolite of BOA. No metabolite accumulation was detected for G. graminis var. avenae and F. culmorum by high-pressure liquid chromatography. The mycelial growth of the pathogenic fungi was inhibited more by BOA and MBOA than by their related fungal metabolites. The tolerance of Gaeumannomyces spp. for benzoxazolinone compounds is correlated with their detoxification ability. The ability of Gaeumannomyces isolates to cause root rot symptoms in wheat (cultivars Rektor and Astron) parallels their potential to degrade wheat allelochemicals to nontoxic compounds.

Friebe, A.; Vilich, V.; Hennig, L.; Kluge, M.; Sicker, D.

1998-01-01

99

Detoxification of Benzoxazolinone Allelochemicals from Wheat by Gaeumannomyces graminis var. tritici, G. graminis var. graminis, G. graminis var. avenae, and Fusarium culmorum.  

PubMed

The ability of phytopathogenic fungi to overcome the chemical defense barriers of their host plants is of great importance for fungal pathogenicity. We studied the role of cyclic hydroxamic acids and their related benzoxazolinones in plant interactions with pathogenic fungi. We identified species-dependent differences in the abilities of Gaeumannomyces graminis var. tritici, Gaeumannomyces graminis var. graminis, Gaeumannomyces graminis var. avenae, and Fusarium culmorum to detoxify these allelochemicals of gramineous plants. The G. graminis var. graminis isolate degraded benzoxazolin-2(3H)-one (BOA) and 6-methoxy-benzoxazolin-2(3H)-one (MBOA) more efficiently than did G. graminis var. tritici and G. graminis var. avenae. F. culmorum degraded BOA but not MBOA. N-(2-Hydroxyphenyl)-malonamic acid and N-(2-hydroxy-4-methoxyphenyl)-malonamic acid were the primary G. graminis var. graminis and G. graminis var. tritici metabolites of BOA and MBOA, respectively, as well as of the related cyclic hydroxamic acids. 2-Amino-3H-phenoxazin-3-one was identified as an additional G. graminis var. tritici metabolite of BOA. No metabolite accumulation was detected for G. graminis var. avenae and F. culmorum by high-pressure liquid chromatography. The mycelial growth of the pathogenic fungi was inhibited more by BOA and MBOA than by their related fungal metabolites. The tolerance of Gaeumannomyces spp. for benzoxazolinone compounds is correlated with their detoxification ability. The ability of Gaeumannomyces isolates to cause root rot symptoms in wheat (cultivars Rektor and Astron) parallels their potential to degrade wheat allelochemicals to nontoxic compounds. PMID:9647804

Friebe; Vilich; Hennig; Kluge; Sicker

1998-07-01

100

Molecular Mechanisms of Bacterial Virulence Elucidated Using a Pseudomonas aeruginosa– Caenorhabditis elegans Pathogenesis Model  

Microsoft Academic Search

The human opportunistic pathogen Pseudomonas aeruginosa strain PA14 kills Caenorhabditis elegans. Using systematic mutagenesis of PA14 to identify mutants that fail to kill C. elegans and a C. elegans mutant that lacks P-glycoproteins, we identified phenazines, secreted P. aeruginosa pigments, as one of the mediators of killing. Analysis of C. elegans mutants with altered responses to oxidative stress suggests that

Shalina Mahajan-Miklos; Man-Wah Tan; Laurence G. Rahme; Frederick M. Ausubel

1999-01-01

101

The Steroid Requirements of Labyrinthula vitellina var. pacifica  

Microsoft Academic Search

Stock cultures of isolates of L. macrocystis var. atlantica and L. minuta var. atlantica were maintained at 20' in tubes containing the semi-solid medium given in Table 1. The addition of 1.0 mg yo (w\\/v) of cholesterol rendered this medium suitable for the maintenance of L. vitellina var. pacifzca. The agar in this medium appears to be necessary as a

HELEN S. VISHNIAC; S. W. WATSON

1953-01-01

102

Beyond VaR: from measuring risk to managing risk  

Microsoft Academic Search

The paper examines tools for managing, as opposed to simply monitoring, a portfolio's value-at-risk (VaR). These tools include the calculation of VaR contribution, marginal VaR and trade risk profiles. We first review the parametric, or delta-normal versions of these tools and then extend them to the simulation based, or nonparametric case. We analyze two sample portfolios: one, consisting of foreign

H. Mausser; D. Rosen

1999-01-01

103

Making Wald Tests Work for Cointegrated Var Systems  

Microsoft Academic Search

Wald tests of restrictions on the coefficients of vector autoregressive (VAR) processesare known to have nonstandard asymptotic properties for I(1) and cointegrated systems ofvariables. A simple device is proposed which guarantees that Wald tests have asymptotic?2--distributions under general conditions. If the true generation process is a VAR(p) it isproposed to fit a VAR(p+1) to the data and perform a Wald

Juan J. DOLADO; Helmut LUETKEPOHL

1994-01-01

104

Making wald tests work for cointegrated VAR systems  

Microsoft Academic Search

Wald tests of restrictions on the coefficients of vector autoregressive (VAR) processes are known to have nonstandard asymptotic properties for 1(1) and cointegrated systems of variables. A simple device is proposed which guarantees that Wald tests have asymptotic X2-distributions under general conditions. If the true generation process is a VAR(p) it is proposed to fit a VAR(p+l) to the data

Juan José Dolado; Helmut Lütkepohl

1996-01-01

105

Membrane Topology of the C. elegans SEL-12 Presenilin  

Microsoft Academic Search

Mutant presenilins cause Alzheimer's disease. Presenilins have multiple hydrophobic regions that could theoretically span a membrane, and a knowledge of the membrane topology is crucial for deducing the mechanism of presenilin function. By analyzing the activity of ?-galactosidase hybrid proteins expressed in C. elegans, we show that the C. elegans SEL-12 presenilin has eight transmembrane domains and that there is

Xiajun Li; Iva Greenwald

1996-01-01

106

Caenorhabditis elegans chemical biology: lessons from small molecules  

Technology Transfer Automated Retrieval System (TEKTRAN)

How can we complement Caenorhabditis elegans genomics and proteomics with a comprehensive structural and functional annotation of its metabolome? Several lines of evidence indicate that small molecules of largely undetermined structure play important roles in C. elegans biology, including key pathw...

107

Every Sperm Is Sacred: Fertilization in Caenorhabditis elegans  

Microsoft Academic Search

The nematode Caenorhabditis elegans is an attractive model system for the study of fertilization. C. elegans exists as a self-fertilizing hermaphrodite or as a male. This unusual situation provides an excellent opportunity to identify and maintain sterile mutants that affect sperm and no other cells. Analysis of these mutants can identify genes that encode proteins required for gamete recognition, adhesion,

Andrew Singson

2001-01-01

108

A novel mode of ecdysozoan growth in Caenorhabditis elegans  

Microsoft Academic Search

SUMMARY Whereas growth in many ecdysozoa is associ- ated with only molting, larval growth in nematodes, specifical- ly Caenorhabditis elegans , is thought to be continuous and exponential. However, this has never been closely investigat- ed. Here we report several detailed studies of growth in wild- type and dwarf C. elegans strains. We find that apparent ex- ponential growth between

Christopher G. Knight; Mavji N. Patel; Ricardo B. R. Azevedo; Armand M. Leroi

2002-01-01

109

RNA interference is an antiviral defence mechanism in Caenorhabditis elegans  

Microsoft Academic Search

RNA interference (RNAi) is an evolutionarily conserved sequence-specific post-transcriptional gene silencing mechanism that is well defined genetically in Caenorhabditis elegans. RNAi has been postulated to function as an adaptive antiviral immune mechanism in the worm, but there is no experimental evidence for this. Part of the limitation is that there are no known natural viral pathogens of C. elegans. Here

Courtney Wilkins; Ryan Dishongh; Steve C. Moore; Michael A. Whitt; Marie Chow; Khaled Machaca

2005-01-01

110

Subcomplex Ilambda Specifically Controls Integrated Mitochondrial Functions in Caenorhabditis elegans  

Microsoft Academic Search

Complex I dysfunction is a common, heterogeneous cause of human mitochondrial disease having poorly understood pathogenesis. The extensive conservation of complex I composition between humans and Caenorhabditis elegans permits analysis of individual subunit contribution to mitochondrial functions at both the whole animal and mitochondrial levels. We provide the first experimentally-verified compilation of complex I composition in C. elegans, demonstrating 84%

Marni J. Falk; Julie R. Rosenjack; Erzsebet Polyak; Wichit Suthammarak; Zhongxue Chen; Phil G. Morgan; Margaret M. Sedensky; Gustavo Goldman

2009-01-01

111

Using Transgenic Caenorhabditis elegans in Soil Toxicity Testing  

Microsoft Academic Search

Soil bioassays are important tools for evaluating toxicological effects within the terrestrial environment. The American Society for Testing and Materials E2172-01 Standard Guide outlines a method for conducting laboratory soil toxicity tests using the nematode Caenorhabditis elegans. This method is an efficient tool for extracting C. elegans from soil samples and can be carried out after a 24-h exposure period

Amber L. Graves; Windy A. Boyd; Phillip L. Williams

2005-01-01

112

Chromosome dosage as a life span determinant in Caenorhabiditis elegans  

Microsoft Academic Search

Caenorhabiditis elegans males live longer than hermaphrodites when cultured individually. Since hermaphrodites contain a pair of X chromosomes (XX) and males are XO (there is no Y chromosome in C. elegans), we questioned whether chromosomal differences per se might impact life span. The use of mutations in the sex-determination genes tra-1 and her-1 allowed us to uncouple sexual phenotype from

Phil S. Hartman; Naoaki Ishii

2007-01-01

113

CRISPR/Cas9-Targeted Mutagenesis in Caenorhabditis elegans  

PubMed Central

The generation of genetic mutants in Caenorhabditis elegans has long relied on the selection of mutations in large-scale screens. Directed mutagenesis of specific loci in the genome would greatly speed up analysis of gene function. Here, we adapt the CRISPR/Cas9 system to generate mutations at specific sites in the C. elegans genome.

Waaijers, Selma; Portegijs, Vincent; Kerver, Jana; Lemmens, Bennie B. L. G.; Tijsterman, Marcel; van den Heuvel, Sander; Boxem, Mike

2013-01-01

114

C. elegans behavior of preference choice on bacterial food.  

PubMed

Caenorhabditis elegans is a free living soil nematode and thus in its natural habitat, C. elegans encounters many different species of soil bacteria. Although some soil bacteria may be excellent sources of nutrition for the worm, others may be pathogenic. Thus, we undertook a study to understand how C. elegans can identify their preferred food using a simple behavioral assay. We found that there are various species of soil bacteria that C. elegans prefers in comparison to the standard laboratory E. coli strain OP50. In particular, two bacterial strains, Bacillus mycoides and Bacillus soli, were preferred strains. Interestingly, the sole feeding of these bacteria to wild type animals results in extended lifespan through the activation of the autophagic process. Further studies will be required to understand the precise mechanism controlling the behavior of identification and selection of food in C. elegans. PMID:19756391

Abada, Emad Abd-elmoniem; Sung, Hyun; Dwivedi, Meenakshi; Park, Byung-Jae; Lee, Sun-Kyung; Ahnn, Joohong

2009-09-01

115

Caenorhabditis elegans swimming in a saturated particulate system  

NASA Astrophysics Data System (ADS)

Caenorhabditis elegans (C. elegans) is a nematode that often swims in saturated soil in nature. We investigated the locomotive behavior of C. elegans swimming in a fluid with particles of various sizes and found that the nematode swims a greater distance per undulation than it does in a fluid without particles. The Strouhal number (a ratio of lateral to forward velocity) of C. elegans significantly decreases in a saturated particulate medium (0.50+/-0.13) in comparison to a fluid without particles (1.6+/-0.27). This result was unexpected due to the generally low performance of a body moving in a high drag medium. In our model, a saturated granular system is approximated as a porous medium where only the hydrodynamic forces on the body are considered. Combining these assumptions with resistive force theory, we find that a porous medium provides more asymmetric drag on a slender body, and consequently that C. elegans locomotes with a greater distance per undulation.

Jung, Sunghwan

2010-03-01

116

40 CFR 80.170 - Volumetric additive reconciliation (VAR), equipment calibration, and recordkeeping requirements.  

Code of Federal Regulations, 2010 CFR

...false Volumetric additive reconciliation (VAR), equipment calibration, and recordkeeping...170 Volumetric additive reconciliation (VAR), equipment calibration, and recordkeeping...additized unless otherwise noted in supporting VAR records, and must be accounted for in...

2010-07-01

117

40 CFR 80.170 - Volumetric additive reconciliation (VAR), equipment calibration, and recordkeeping requirements.  

Code of Federal Regulations, 2010 CFR

...false Volumetric additive reconciliation (VAR), equipment calibration, and recordkeeping...170 Volumetric additive reconciliation (VAR), equipment calibration, and recordkeeping...additized unless otherwise noted in supporting VAR records, and must be accounted for in...

2009-07-01

118

Terpenoids from Tripterygium wilfordii var. regelii  

Microsoft Academic Search

The methanol extract of dried stem barks of Tripterygium wilfordii Hook fil. var regelii afforded two new triterpenes: 22-hydroxy-3, 19,24-trinor-D:A-friedoolenane-1(10), 5, 7-triene-2-oic acid methyl ester, named regelone, and 3-methyl-23-ol-oxotingenol; a new diterpene—8?, 19-dihydroxy-3-oxopimar- 15-ene; and three known triterpenes-3-methyl-22-?, 23-diol-6-oxotingenol, tingenin B and cangoronin. Their structures were established on the basis of chemical and spectroscopic studies. ©1997 Elsevier Science Ltd. All

Yoshihisa Takaishi; Kaname Miyagi; Kazuyoshi Kawazoe; Kimiko Nakano; Kunhua Li; Hongquan Duan

1997-01-01

119

Origin of Cryptococcus neoformans var. neoformans Diploid Strains  

Microsoft Academic Search

The basidiomycetous yeast Cryptococcus neoformans is an important human fungal pathogen. Two varieties, C. neoformans var. neoformans and C. neoformans var. gattii, have been identified. Both are heterothallic with two mating types, MATa and MAT. Some rare isolates are self-fertile and are considered occasional diploid or aneuploid strains. In the present study, 133 isolates, mostly from Italian patients, were investigated

MASSIMO COGLIATI; MARIA C. ESPOSTO; DAVID L. CLARKE; BRIAN L. WICKES; MARIA A. VIVIANI

2001-01-01

120

Productivity Shocks and the Business Cycle: Reconciling Recent VAR Evidence  

Microsoft Academic Search

Gali (1999) used a VAR with productivity and hours worked to argue that technology shocks are negatively correlated with labor and are unimportant for the business cycle. More recently, Beaudry and Portier (2003) studied a VAR in productivity and stock prices. Remarkably, they found that the component which has a permanent impact on productivity is almost identical to that which

James Costain; Beatriz de-Blas-Perez

2006-01-01

121

A Structural VAR Model of the Australian Economy  

Microsoft Academic Search

We develop an 11-variable structural VAR for the Australian economy over the period 1980 to 1998. The VAR methodology has only relatively recently been applied in the Australian context, despite its popularity in quantitative macroeconomics internationally. Our model includes an overseas sector which distinguishes between goods and asset markets so as to disentangle the effects of shocks emanating from each

Mardi Dungey; Adrian Pagan

2000-01-01

122

Measuring monetary policy with VAR models: An evaluation  

Microsoft Academic Search

This paper evaluates VAR models designed to analyse the monetary policy transmission mechanism in the United States by considering three issues: specification, identification, and the effect of the omission of the long-term interest rate. Specification analysis suggests that only VAR models estimated on a single monetary regime feature parameters stability and do not show signs of mis-specification. The identification analysis

Fabio C. Bagliano; Carlo A. Favero

1998-01-01

123

Impulse response and forecast error variance asymptotics in nonstationary VARs  

Microsoft Academic Search

Estimated impulse responses and forecast error decompositions are shown to be inconsistent at long horizons in unrestricted VARs with some unit roots. Predictions from unrestricted VARs also do not converge to the optimal predictors over long forecast horizons. In contrast, reduced rank regressions produce impulse responses and forecast error variance estimates that are consistent and predictions that are asymptotically optimal,

Peter C. B. Phillips

1998-01-01

124

Dynamic security constrained optimal power flow\\/VAr planning  

Microsoft Academic Search

Traditionally security constrained optimal power flow and VAr planning methods consider static security observing voltage profile and flow constraints under normal and post contingency conditions. Ideally, these formulations should be extended to consider dynamic security. This paper reports on a BC Hydro\\/CEPEL joint effort establishing a dynamic security constrained OPF\\/VAr planning tool which considers simultaneously static constraints as well as

Ebrahim Vaahedi; Yakout Mansour; Chris Fuchs; Sergio Granville; Maria de Lujan Latore; Hamid Hamadanizadeh

2001-01-01

125

Regulation of Sex Determination in C. elegans  

NSDL National Science Digital Library

A demonstration by Dr. Meyer showing how a balance of molecular elements trigger genetic pathways that determine the sex of a C. elegans worm. This video is featured on the HHMI DVD, The Meaning of Sex: Genes and Gender, available free from HHMI. Also, this video is 6 minutes and 3 seconds in length, and available in QuickTime (45 MB) and Windows Media Player (62 MB). All sex determination videos are located at: http://www.hhmi.org/biointeractive/gender/video.html.

Howrad Hughes Medical Institute (HHMI;)

2008-06-09

126

Caenorhabditis elegans as a model for obesity research.  

PubMed

Caenorhabditis elegans (C. elegans) is a small nematode that conserves 65% of the genes associated with human disease, has a 21-day lifespan, reproductive cycles of 3 days, large brood sizes, lives in an agar dish and does not require committee approvals for experimentation. Research using C. elegans is encouraged and a Caenorhabditis Genetics Center (CGC, Minnesota) is funded by the National Institutes of Health-National Center for Research Resources. Many genetically manipulated strains of C. elegans are available at nominal cost from the CGC. Studies using the C. elegans model have explored insulin signaling, response to dietary glucose, the influence of serotonin on obesity, satiety, feeding and hypoxia-associated illnesses. C. elegans has also been used as a model to evaluate potential obesity therapeutics, explore the mechanisms behind single gene mutations related to obesity and to define the mechanistic details of fat metabolism. Obesity now affects a third of the US population and is becoming a progressively more expensive public health problem. Faster and less expensive methods to reach more effective treatments are clearly needed. We present this review hoping to stimulate interest in using the C. elegans model as a vehicle to advance the understanding and future treatment of obesity. PMID:21556043

Zheng, J; Greenway, F L

2011-05-10

127

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

128

Influence of planktonic and sessile Listeria monocytogenes on Caenorhabditis elegans.  

PubMed

Listeria monocytogenes is the etiologic agent of listeriosis, a food-borne disease affecting humans and a variety of animals. In order to combat this pathogen, it is crucial to have an understanding of its natural interplay with the environment. For this reason, the free soil nematode Caenorhabditis elegans was focused upon because of its shared natural habitat with Listeria and its potential as a model organism for Listeria pathogenesis. Previous studies have generated some contradictory results on Listeria's ability to kill C. elegans, making additional interaction studies such as this more attractive. In our study, we carried out a series of killing assays in a systematic manner using different Listeria strains under different growth conditions. In addition to studying the effects of planktonic cells, we examined the interaction between C. elegans and sessile listerial cells. Our findings suggest that, rather than causing infection and death, L. monocytogenes may extend the life span of C. elegans. This indicates that Listeria is not pathogenic to C. elegans. We also found that C. elegans can feed and ingest sessile cells, as well as carry the pathogen in its gut, implying that C. elegans could be a vehicle for L. monocytogenes spread in the environment. PMID:22961596

Guha, Sujay; Klees, Miranda; Wang, Xiaoxia; Li, Jing; Dong, Yuqing; Cao, Min

2012-09-09

129

Genetic differentiation between Coffea liberica var. liberica and C. liberica var. Dewevrei and comparison with C. canephora  

Microsoft Academic Search

Coffea liberica Hiern includes C. liberica var. liberica (LIB) from western Africa and C. liberica var. dewevrei (DEW) from central Africa. This geographical distribution also includes cultivated C. canephora for which a within-species clustering in two interfertile groups is known. In this study, genetic differentiation between LIB and DEW was evaluated on the basis of morphological traits, molecular markers (AFLP)

A. N’Diaye; V. Poncet; J. Louarn; S. Hamon; M. Noirot

2005-01-01

130

COCCONEIS COSTATA VAR. SUBANTARCTICA VAR. NOV., A NEW MARINE DIATOM OFF KERGUELEN ARCHIPELAGO (SOUTHERN OCEAN, INDIAN SECTOR)  

Microsoft Academic Search

Cocconeis costata var. subantarctica var. no v., a rare taxon from the Kerguelen Archipelago (Southern Ocean, Indian sector), is described using light and scanning electron microscope observations and was compared to related taxa. Apart from the wide-elliptical central area devoid of striae, the raphe valve features highly resemble those of the C. costata complex: the open crista marginalis is similar

Catherine Riaux-Gobin; Oscar E. Romero; Adil Y. Al-Handal

2009-01-01

131

Cellular Symmetry Breaking during Caenorhabditis elegans Development  

PubMed Central

The nematode worm Caenorhabditis elegans has produced a wellspring of insights into mechanisms that govern cellular symmetry breaking during animal development. Here we focus on two highly conserved systems that underlie many of the key symmetry-breaking events that occur during embryonic and larval development in the worm. One involves the interplay between Par proteins, Rho GTPases, and the actomyosin cytoskeleton and mediates asymmetric cell divisions that establish the germline. The other uses elements of the Wnt signaling pathway and a highly reiterative mechanism that distinguishes anterior from posterior daughter cell fates. Much of what we know about these systems comes from intensive study of a few key events—Par/Rho/actomyosin-mediated polarization of the zygote in response to a sperm-derived cue and the Wnt-mediated induction of endoderm at the four-cell stage. However, a growing body of work is revealing how C. elegans exploits elements/variants of these systems to accomplish a diversity of symmetry-breaking tasks throughout embryonic and larval development.

Munro, Edwin; Bowerman, Bruce

2009-01-01

132

Morphogenesis of the caenorhabditis elegans vulva.  

PubMed

Understanding how cells move, change shape, and alter cellular behaviors to form organs, a process termed morphogenesis, is one of the great challenges of developmental biology. Formation of the Caenorhabditis elegans vulva is a powerful, simple, and experimentally accessible model for elucidating how morphogenetic processes produce an organ. In the first step of vulval development, three epithelial precursor cells divide and differentiate to generate 22 cells of 7 different vulval subtypes. The 22 vulval cells then rearrange from a linear array into a tube, with each of the seven cell types undergoing characteristic morphogenetic behaviors that construct the vulva. Vulval morphogenesis entails many of the same cellular activities that underlie organogenesis and tissue formation across species, including invagination, lumen formation, oriented cell divisions, cell–cell adhesion, cell migration, cell fusion, extracellular matrix remodeling, and cell invasion. Studies of vulval development have led to pioneering discoveries in a number of these processes and are beginning to bridge the gap between the pathways that specify cells and their connections to morphogenetic behaviors. The simplicity of the vulva and the experimental tools available in C. elegans will continue to make vulval morphogenesis a powerful paradigm to further our understanding of the largely mysterious mechanisms that build tissues and organs. PMID:23418408

Schindler, Adam J; Sherwood, David R

133

Developmental transitions in C. elegans larval stages.  

PubMed

Molecular mechanisms control the timing, sequence, and synchrony of developmental events in multicellular organisms. In Caenorhabditis elegans, these mechanisms are revealed through the analysis of mutants with "heterochronic" defects: cell division or differentiation patterns that occur in the correct lineage, but simply at the wrong time. Subsets of cells in these mutants thus express temporal identities normally restricted to a different life stage. A seminal finding arising from studies of the heterochronic genes was the discovery of miRNAs; these tiny miRNAs are now a defining feature of the pathway. A series of sequentially expressed miRNAs guide larval transitions through stage-specific repression of key effector molecules. The wild-type lineage patterns are executed as discrete modules programmed between temporal borders imposed by the molting cycles. How these successive events are synchronized with the oscillatory molting cycle is just beginning to come to light. Progression through larval stages can be specifically, yet reversibly, halted in response to environmental cues, including nutrient availability. Here too, heterochronic genes and miRNAs play key roles. Remarkably, developmental arrest can, in some cases, either mask or reveal timing defects associated with mutations. In this chapter, we provide an overview of how the C. elegans heterochronic gene pathway guides developmental transitions during continuous and interrupted larval development. PMID:23962842

Rougvie, Ann E; Moss, Eric G

2013-01-01

134

Agrobacterium tumefaciens -mediated transformation of broccoli ( Brassica oleracea var. italica ) and cabbage ( B. oleracea var. capitata )  

Microsoft Academic Search

Transgenic broccoli (Brassica oleracea var. italica) was produced by two Agrobacterium tumefaciens-mediated transformation methods. One used flowering stalk explants from mature plants; the other used hypocotyl and petiole explants from in vitro-grown seedlings. Several hundred transformants containing a Bacillus thuringiensis ?-endotoxin gene (CryIA(c)-type) and the neomycin phosphotransferase gene were recovered. Rooted transformants were obtained in as little as 3 months

Timothy D. Metz; Ram Dixit; Elizabeth D. Earle

1995-01-01

135

Microfluidics as a tool for C. elegans research.  

PubMed

Microfluidics has emerged as a set of powerful tools that have greatly advanced some areas of biological research, including research using C. elegans. The use of microfluidics has enabled many experiments that are otherwise impossible with conventional methods. Today there are many examples that demonstrate the main advantages of using microfluidics for C. elegans research, achieving precise environmental conditions and facilitating worm handling. Examples range from behavioral analysis under precise chemical or odor stimulation, locomotion studies in well-defined structural surroundings, and even long-term culture on chip. Moreover, microfluidics has enabled coupling worm handling and imaging thus facilitating genetic screens, optogenetic studies, and laser ablation experiments. In this article, we review some of the applications of microfluidics for C. elegans research and provide guides for the design, fabrication, and use of microfluidic devices for C. elegans research studies. PMID:24065448

San-Miguel, Adriana; Lu, Hang

2013-09-24

136

Chromosome-scale selective sweeps shape Caenorhabditis elegans genomic diversity  

PubMed Central

The nematode Caenorhabditis elegans is central to research in molecular, cell, and developmental biology, but nearly all of this research has been conducted on a single strain. Comparatively little is known about the population genomic and evolutionary history of this species. We characterized C. elegans genetic variation by high-throughput selective sequencing of a worldwide collection of 200 wild strains, identifying 41,188 single nucleotide polymorphisms. Unexpectedly, C. elegans genome variation is dominated by a set of commonly shared haplotypes on four of the six chromosomes, each spanning many megabases. Population-genetic modeling shows that this pattern was generated by chromosome-scale selective sweeps that have reduced variation worldwide; at least one of these sweeps likely occurred in the past few hundred years. These sweeps, which we hypothesize to be a result of human activity, have dramatically reshaped the global C. elegans population in the recent past.

Andersen, Erik C.; Gerke, Justin P.; Shapiro, Joshua A.; Crissman, Jonathan R.; Ghosh, Rajarshi; Bloom, Joshua S.; Felix, Marie-Anne; Kruglyak, Leonid

2011-01-01

137

Isolation of Caenorhabditis elegans mutants lacking alcohol dehydrogenase activity.  

PubMed

Alcohol dehydrogenase (ADH) and the genes encoding this enzyme have been studied intensively in a broad range of organisms. Little, however, has been reported on ADH in the free-living nematode Caenorhabditis elegans. Extracts of wild-type C. elegans contain ADH activity and display a single band of activity on a native polyacrylamide gel. Reaction rate for alcohol oxidation is more rapid with higher molecular weight alcohols as substrate than with ethanol. Primary alcohols are preferred to secondary alcohols. C. elegans is sensitive to allyl alcohol, a compound that has been used to select for ADH-null mutants of several organisms. Allyl alcohol-resistant mutant strains were selected from ethylmethanesulfonate (EMS)-mutagenized nematode populations. ADH activity was measured in extracts from eight of these strains and was found to be low or nondetectable. These results form a basis for molecular and genetic characterization of ADH expression in C. elegans. PMID:1747095

Williamson, V M; Long, M; Theodoris, G

1991-08-01

138

Genetic Analysis of the Vulval Cell Lineages of 'Caenorhabditis elegans'.  

National Technical Information Service (NTIS)

The cell lineages of the nematode Caenorhabditis elegans are essentially invariant among individuals. Researchers have begun an attempt to understand the genetic specification of one particular cell lineage, that of the hermaphrodite vulva. During vulval ...

E. L. Ferguson

1985-01-01

139

Lipid droplets as fat storage organelles in Caenorhabditis elegans  

PubMed Central

Lipid droplets are evolutionarily conserved organelles where cellular fat storage and mobilization are exquisitely regulated. Recent studies have defined lipid droplets in C. elegans and explored how they are regulated by genetic and dietary factors. C. elegans offers unique opportunities to visualize lipid droplets at single-cell resolution in live animals. The development of novel microscopy techniques and protein markers for lipid droplets will accelerate studies on how nutritional states and subcellular organization are linked in vivo. Together with powerful tools for genetic and biochemical analysis of metabolic pathways, alteration in lipid droplet abundance, size, and distribution in C. elegans can be readily connected to whole-animal energy homeostasis, behavior, and life span. Therefore, further studies on lipid droplets in C. elegans promise to yield valuable insights that complement our knowledge gained from yeast, Drosophila, and mammalian systems on cellular and organismal fat storage.

Mak, Ho Yi

2012-01-01

140

Caenorhabditis elegans: an emerging model in biomedical and environmental toxicology.  

PubMed

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

2008-06-19

141

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.

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

2008-01-01

142

The Spectral Sensitivity of the Turtle. 'Pseudemys scripta elegans'.  

National Technical Information Service (NTIS)

The study deals with the determination of the spectral sensitivity of the turtle Pseudemys scripta elegans. The approach used herein is behavioral rather than electrophysiological in nature, and thereby provides data which, when used in conjunction with t...

L. Menaffey

1971-01-01

143

Phenolic diterpenes from Tripterygium wilfordii var. regelii  

Microsoft Academic Search

Seven new phenolic abietane type diterpenoids: 14, 19-dihydroxy-3-oxo-abieta-8, 11, 13-triene; 3,14-dihydroxy-abieta-8, 11, 13-triene; 14, 19-dihydroxy-3,7-dioxo-abieta-8, 11, 13-triene; 18(4 ? 3)-abeo-abieta-3,8,11,13-tetraene-18-oic acid; 18(4 ? 3)-abeo-14, 15-dihydroxy-abieta-3, 8, 11, 13-tetraene-18,19-olide; 18(4 ? 3)-abeo-abieta-14,16-dihydroxy-abieta-3,8,11,13-tetraene-18,19-olide; 18(4 ? 3)-abeo-abieta-14, 17-dihydroxy-abieta-3,8,11,13-tetraene-18,19-olide named triptobenzene A, B, C, D, E, F and G have been isolated from Tripterygium wilfordii var. regelii. Their structures have been established on the

Yoshihisa Takaishi; Noriko Wariishi; Hideo Tateishi; Kazuyoshi Kawazoe; Kaname Miyagi; Kunhua Li; Hongquan Duan

1997-01-01

144

Pregnane alkaloids from Sarcococca hookeriana var. digyna.  

PubMed

Fourteen pregnane-type steroidal alkaloids were isolated from the ethanolic extracts of whole Sarcococca hookeriana var. digyna plants. Their structures were elucidated on the basis of spectral data. Three of them were identified as new steroidal alkaloids: (S)-20-(N,N-dimethylamino)-16?,17?-epoxy-3?-methoxy-pregn-5-ene (1), (20S)-20-(N,N-dimethylamino)-3?-tigloylamino-5?-pregn-11?-ol (2), and (20S)-2?,4?-bis(acetoxy)-20-(N,N-dimethylamino)-3?-tigloylamino-5?-pregnane (3). Some of the isolated compounds showed estrogen biosynthesis-promoting effects in human ovarian granulosa-like KGN cells. The EC50 values for the most effective compounds, vagnine B (6) and funtumafrine C (12), were 71 ?M and 67 ?M, respectively. PMID:23651560

Zhang, Pu-zhao; Wang, Fei; Yang, Li-juan; Zhang, Guo-lin

2013-05-05

145

BROAD OXYGEN TOLERANCE IN THE NEMATODE CAENORHABDITIS ELEGANS  

Microsoft Academic Search

This study examined the effects of oxygen tensions ranging from 0 to 90 kPa on the metabolic rate (rate of carbon dioxide production), movement and survivorship of the free-living soil nematode Caenorhabditis elegans. C. elegans requires oxygen to develop and survive. However, it can maintain a normal metabolic rate at oxygen levels of 3.6 kPa and has near-normal metabolic rates

WAYNE A. VAN VOORHIES; SAMUEL WARD

146

Isolation of Caenorhabditis elegans mutants lacking alcohol dehydrogenase activity  

Microsoft Academic Search

Alcohol dehydrogenase (ADH) and the genes encoding this enzyme have been studied intensively in a broad range of organisms. Little, however, has been reported on ADH in the free-living nematodeCaenorhabiditis elegans. Extracts of wild-typeC. elegans contain ADH activity and display a single band of activity on a native polyacrylamide gel. Reaction rate for alcohol oxidation is more rapid with higher

Valerie M. Williamson; Manyuan Long; George Theodoris

1991-01-01

147

Tomosyn Inhibits Synaptic Vesicle Priming in Caenorhabditis elegans  

Microsoft Academic Search

Caenorhabditis elegans TOM-1 is orthologous to vertebrate tomosyn, a cytosolic syntaxin-binding protein implicated in the modulation of both constitutive and regulated exocytosis. To investigate how TOM-1 regulates exocytosis of synaptic vesicles in vivo, we analyzed C. elegans tom-1 mutants. Our electrophysiological analysis indicates that evoked postsynaptic responses at tom-1 mutant synapses are prolonged leading to a two-fold increase in total

Elena O Gracheva; Anna O Burdina; Andrea M Holgado; Martine Berthelot-Grosjean; Brian D Ackley; Gayla Hadwiger; Michael L Nonet; Robby M Weimer; Janet E Richmond

2006-01-01

148

Structural analysis of hyperperiodic DNA from Caenorhabditis elegans  

Microsoft Academic Search

Several bioinformatics studies have identified an unexpected but remarkably prevalent ? 10 bp peri- odicity of AA\\/TT dinucleotides (hyperperiodicity) in certain regions of the Caenorhabditis elegans gen- ome. Although the relevant C.elegans DNA seg- ments share certain sequence characteristics with bent DNAs from other sources (e.g. trypanosome mitochondria), the nematode sequences exhibit a much more extensive and defined hyperperiodicity. Given

Fernando Moreno-Herrero; Ralf Seidel; Steven M. Johnson; Andrew Fire; Nynke H. Dekker

2006-01-01

149

Characterization of the effects of methylmercury on Caenorhabditis elegans  

Microsoft Academic Search

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

Kirsten J. Helmcke; Tore Syversen; David M. Miller III; Michael Aschner

2009-01-01

150

Sensing of Heavy Metals Using Caenorhabditis elegans DNA Microarray  

Microsoft Academic Search

Abstract—Previously we reported that the possibility of sensing of chemical substances using gene expression patterns analyzed,by DNA microarray using Caenorhabditis elegans( C. elegans) as a sensor (Matsuno et al., 2002, 2006). In this study, we evaluated sensitivity and selectivity of above system using a customized,DNA microarray ,for heavy ,metal responded ,genes. The results showed,that this system ,showed ,high sensitivity and

Nobuaki TOMINAGA; Tetsuya MATSUNO; Shinya KOHRA; Koji ARIZONO

151

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

152

Microbial Interactions with Caenorhabditis elegans : Lessons from a Model Organism  

Microsoft Academic Search

\\u000a In recent years, the study of invertebrate innate immune defense responses has been greatly expanded by the use of the powerful\\u000a tractable model Caenorhabditis elegans. Because of the accessible mechanisms underpinning its innate immune system, the worm has become into a valuable model for\\u000a identifying core strategies of microbial pathogenicity and host defense. C. elegans-microbial interaction studies have revealed a

Maria J. Gravato-Nobre; Jonathan Hodgkin

153

Cytoskeletal Dynamics in Caenorhabditis elegans Axon Regeneration.  

PubMed

Axon regeneration after damage is widespread in the animal kingdom, and the nematode Caenorhabditis elegans has recently emerged as a tractable model in which to study the genetics and cell biology of axon regrowth in vivo. A key early step in axon regrowth is the conversion of part of a mature axon shaft into a growth cone-like structure, involving coordinated alterations in the microtubule, actin, and neurofilament systems. Recent attention has focused on microtubule dynamics as a determinant of axon-regrowth ability in several organisms. Live imaging studies have begun to reveal how the microtubule cytoskeleton is remodeled after axon injury, as well as the regulatory pathways involved. The dual leucine zipper kinase family of mixed-lineage kinases has emerged as a critical sensor of axon damage and plays a key role in regulating microtubule dynamics in the damaged axon. PMID:23844582

Chisholm, Andrew D

2013-07-10

154

Ultrafast endocytosis at Caenorhabditis elegans neuromuscular junctions.  

PubMed

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

2013-09-03

155

Prostaglandin extraction and analysis in Caenorhabditis elegans.  

PubMed

Caenorhabditis elegans is emerging as a powerful animal model to study the biology of lipids(1-9). Prostaglandins are an important class of eicosanoids, which are lipid signals derived from polyunsaturated fatty acids (PUFAs)(10-14). These signalling molecules are difficult to study because of their low abundance and reactive nature. The characteristic feature of prostaglandins is a cyclopentane ring structure located within the fatty acid backbone. In mammals, prostaglandins can be formed through cyclooxygenase enzyme-dependent and -independent pathways(10,15). C. elegans synthesizes a wide array of prostaglandins independent of cyclooxygenases(6,16,17). A large class of F-series prostaglandins has been identified, but the study of eicosanoids is at an early stage with ample room for new discoveries. Here we describe a procedure for extracting and analyzing prostaglandins and other eicosanoids. Charged lipids are extracted from mass worm cultures using a liquid-liquid extraction technique and analyzed by liquid chromatography coupled to electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). The inclusion of deuterated analogs of prostaglandins, such as PGF2 ?-d4 as an internal standard is recommended for quantitative analysis. Multiple reaction monitoring or MRM can be used to quantify and compare specific prostaglandin types between wild-type and mutant animals. Collision-induced decomposition or MS/MS can be used to obtain information on important structural features. Liquid chromatography mass spectrometry (LC-MS) survey scans of a selected mass range, such as m/z 315-360 can be used to evaluate global changes in prostaglandin levels. We provide examples of all three analyses. These methods will provide researchers with a toolset for discovering novel eicosanoids and delineating their metabolic pathways. PMID:23851568

Prasain, Jeevan K; Hoang, Hieu D; Edmonds, Johnathan W; Miller, Michael A

2013-06-25

156

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...

157

Multilocus microsatellite typing for Cryptococcus neoformans var. grubii.  

PubMed

Fifteen randomly selected microsatellites (simple sequence repeats; SSRs), from the H99 Cryptococcus neoformans var. grubii (serotype A) genome, were sequenced, characterized and applied to sequence 87 clinical and environmental C. neoformans var. grubii isolates from 12 different countries based on Multilocus Microsatellite Typing (MLMT). Among the 15 SSR loci, three (designated CNG1, CNG2 and CNG3) were polymorphic, while the remaining 12 SSR loci showed no variations. The specific PCR primers of the polymorphic microsatellites, i.e., CNG1, CNG2 and CNG3, amplified those loci only from strains of C. neoformans (C. neoformans var. grubii, C. neoformans var. neoformans and the AD hybrid) but not from Cryptococcus gattii, suggesting a species-specific association. The three polymorphic microsatellites are useful markers for strain genotyping, population genetic analysis, epidemiological studies, and may be helpful for the diagnosis of cryptococcosis due to C. neoformans. PMID:18608927

Hanafy, Ahmed; Kaocharoen, Sirada; Jover-Botella, Alejandro; Katsu, Masakazu; Iida, Soji; Kogure, Takahisa; Gonoi, Tohru; Mikami, Yuzuru; Meyer, Wieland

2008-11-01

158

Michigan Monkey-Flower ('Mimulus glabratus var. michiganensis') Recovery Plan.  

National Technical Information Service (NTIS)

Mirnulus glabratus var. michiganensis (Pennell) Fassett, (Michigan monkey-flower), a member of the Scrophulariaceae (snapdragon family), is an endemic variety of a widespread and diverse complex of yellow monkey-flowers. The taxon is known from only 15 ex...

M. R. Penskar

1997-01-01

159

Puccinia jaceae var.solstitialis teliospore priming on yellow starthistle  

Technology Transfer Automated Retrieval System (TEKTRAN)

Following the introduction of Puccinia jaceae var. solstitialis to California for biological control of yellow starthistle (Centaurea solstitialis, Asteraceae), teliospores, pycnia, and multiple urediniospore generations have been observed in the field. Because urediniospores have a relatively short...

160

Investigations on the Red-Eared Slider Turtle, 'Trachemys scripta elegans'. Long Term Resource Monitoring Program.  

National Technical Information Service (NTIS)

Contents: Preface; Kyphosis in the red-eared sider turtle (Trachemys scripta elegans); Order of oviposition and egg size in the red-eared slider turtle (Trachemys scripta elegans); Overwinter survival by hatchling sliders (trachemys scripta) in west-centr...

J. K. Tucker N. I. Filoramo F. J. Janzen G. C. Packard G. L. Paukstis

1999-01-01

161

Effects of sterols on the development and aging of caenorhabditis elegans  

Technology Transfer Automated Retrieval System (TEKTRAN)

Because Caenorhabditis elegans lacks several components of the de novo sterol biosynthesis pathway, it requires sterols as essential nutrients. Supplemented cholesterol undergoes extensive enzymatic modification in C. elegans to form other sterols of unknown function. Because sterol metabolism in ...

162

Catabolic pathways of glucose in Bacillus circulans var. alkalophilus  

Microsoft Academic Search

Enzymes and the metabolic pathways of glucose catabolism of Bacillus circulans var. alkalophilus were studied. The metabolism of the microbe was mixed acid fermentative yielding mainly acetic and formic acids as end products\\u000a from glucose. It was estimated that B. circulans var. alkalophilus partitions 90%–93% of the carbon from glucose into the Embden-Meyerhof-Parnas (EMP) pathway and 7%–10% into the hexose

Sari Paavilainen; Soili Oinonen; Timo Korpela

1999-01-01

163

Some tests for parameter constancy in cointegrated VAR-models  

Microsoft Academic Search

Some methods for the evaluation of parameter constancy in cointegrated vector autoregressive (VAR) models are discussed. Two different ways of re-estimating the VAR-model are proposed; one in which all parameters are estimated recursively based upon the likelihood function for the first observations, and another in which the cointegrating relations are estimated recursively from a likelihood function, where the short-run parameters

HENRIK HANSEN; SØREN JOHANSEN

1999-01-01

164

Scientific Investigations on the Red-Eared Turtle, 'Trachemys scripta elegans'. Long Term Resource Monitoring Program.  

National Technical Information Service (NTIS)

Contents: Melanism in the Red-eared Slider (Trachemys scripta elegans); Salvage of Eggs from Road-killd Red-eared Sliders, Trachemys scripta elegans; Unusual Coloration in a Red-eared Slider, Trachemys scripta elegans; Fences and Nesting Red-eared Sliders...

J. K. Tucker F. A. Cronin B. J. Kerans N. I. Filoramo F. J. Janzen G. L. Paukstis C. H. Theiling D. Moll R. J. Maher

1997-01-01

165

Analysis of synaptic transmission in Caenorhabditis elegans using an aldicarb-sensitivity assay  

Microsoft Academic Search

Caenorhabditis elegans has emerged as a powerful model system for studying the biology of the synapse. Here we describe a widely used assay for synaptic transmission at the C. elegans neuromuscular junction. This protocol monitors the sensitivity of C. elegans to the paralyzing affects of an acetylcholinesterase inhibitor, aldicarb. Briefly, adult worms are incubated in the presence of aldicarb and

Timothy R Mahoney; Shuo Luo; Michael L Nonet

2006-01-01

166

Something worth dyeing for: Molecular tools for the dissection of lipid metabolism in Caenorhabditis elegans  

Microsoft Academic Search

The nematode Caenorhabditis elegans (C. elegans) has during the last decade emerged as an invaluable eukaryotic model organism to understand the metabolic and neuro-endocrine regulation of lipid accumulation. The fundamental pathways of food intake, digestion, metabolism, and signalling are evolutionary conserved between mammals and worms making C. elegans a genetically and metabolically extremely tractable model to decipher new regulatory mechanisms

Ida Coordt Elle; Louise Cathrine Braun Olsen; Dennis Pultz; Steven Vestergaard Rødkær; Nils Joakim Færgeman

2010-01-01

167

Pseudomonas aeruginosa killing of Caenorhabditis elegans used to identify P. aeruginosa virulence factors  

Microsoft Academic Search

We reported recently that the human oppor- tunistic pathogen Pseudomonas aeruginosa strain PA14 kills Caenorhabditis elegans and that many P. aeruginosa virulence factors (genes) required for maximum virulence in mouse patho- genicity 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,

MAN-WAH TAN; L AURENCE G. RAHME; A. STERNBERG; R ONALD G. TOMPKINS; FREDERICK M. AUSUBEL

1999-01-01

168

40 CFR 180.1243 - Bacillus subtilis var. amyloliquefaciens strain FZB24; exemption from the requirement of a...  

Code of Federal Regulations, 2011 CFR

...2013-07-01 2013-07-01 false Bacillus subtilis var. amyloliquefaciens strain...Exemptions From Tolerances § 180.1243 Bacillus subtilis var. amyloliquefaciens ...requirement of a tolerance for residues of the Bacillus subtilis var....

2013-07-01

169

40 CFR 180.1243 - Bacillus subtilis var. amyloliquefaciens strain FZB24; exemption from the requirement of a...  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Bacillus subtilis var. amyloliquefaciens strain...Tolerances § 180.1243 Bacillus subtilis var. amyloliquefaciens ...tolerance for residues of the Bacillus subtilis var....

2010-07-01

170

40 CFR 180.1243 - Bacillus subtilis var. amyloliquefaciens strain FZB24; exemption from the requirement of a...  

Code of Federal Regulations, 2010 CFR

...2009-07-01 2009-07-01 false Bacillus subtilis var. amyloliquefaciens strain...Tolerances § 180.1243 Bacillus subtilis var. amyloliquefaciens ...tolerance for residues of the Bacillus subtilis var....

2009-07-01

171

Genome-wide analysis of alternative splicing in Caenorhabditis elegans.  

PubMed

Alternative splicing (AS) plays a crucial role in the diversification of gene function and regulation. Consequently, the systematic identification and characterization of temporally regulated splice variants is of critical importance to understanding animal development. We have used high-throughput RNA sequencing and microarray profiling to analyze AS in C. elegans across various stages of development. This analysis identified thousands of novel splicing events, including hundreds of developmentally regulated AS events. To make these data easily accessible and informative, we constructed the C. elegans Splice Browser, a web resource in which researchers can mine AS events of interest and retrieve information about their relative levels and regulation across development. The data presented in this study, along with the Splice Browser, provide the most comprehensive set of annotated splice variants in C. elegans to date, and are therefore expected to facilitate focused, high resolution in vivo functional assays of AS function. PMID:21177968

Ramani, Arun K; Calarco, John A; Pan, Qun; Mavandadi, Sepand; Wang, Ying; Nelson, Andrew C; Lee, Leo J; Morris, Quaid; Blencowe, Benjamin J; Zhen, Mei; Fraser, Andrew G

2010-12-22

172

Transfer characteristics of a thermosensory synapse in Caenorhabditis elegans  

PubMed Central

Caenorhabditis elegans is a compact, attractive system for neural circuit analysis. An understanding of the functional dynamics of neural computation requires physiological analyses. We undertook the characterization of transfer at a central synapse in C. elegans by combining optical stimulation of targeted neurons with electrophysiological recordings. We show that the synapse between AFD and AIY, the first stage in the thermotactic circuit, exhibits excitatory, tonic, and graded release. We measured the linear range of the input-output curve and estimate the static synaptic gain as 0.056 (<0.1). Release showed no obvious facilitation or depression. Transmission at this synapse is peptidergic. The AFD/AIY synapse thus seems to have evolved for reliable transmission of a scaled-down temperature signal from AFD, enabling AIY to monitor and integrate temperature with other sensory input. Combining optogenetics with electrophysiology is a powerful way to analyze C. elegans’ neural function.

Narayan, Anusha; Laurent, Gilles; Sternberg, Paul W.

2011-01-01

173

Locomotion of C. elegans through jammed granular media  

NASA Astrophysics Data System (ADS)

It is quantitatively demonstrated in this experiment on the undulatory swimming of C. (Caenorhabditis) elegans that, in a highly-resistive media, the animal only executes beating frequencies and amplitudes in discrete values. This behavior of C. elegans is inferred from the peaks in the particle velocity distributions where the most probable velocities match the transverse velocities of the nematode body. The behavior in the velocity distribution is more pronounced for particles in denser arrangements and for those closer to the thrashing gait of the worm. These results contribute to the existing data on the worm locomotion and further facilitate the identification of the endogenous genes and neural circuitry to the exogenous behavioral responses of C. elegans.

Lu, Kevin; Arratia, Paulo E.

2009-03-01

174

Odour concentration-dependent olfactory preference change in C. elegans.  

PubMed

The same odorant can induce attractive or repulsive responses depending on its concentration in various animals including humans. However, little is understood about the neuronal basis of this behavioural phenomenon. Here we show that Caenorhabditis elegans avoids high concentrations of odorants that are attractive at low concentrations. Behavioural analyses and computer simulation reveal that the odour concentration-dependent behaviour is primarily generated by klinokinesis, a behavioural strategy in C. elegans. Genetic analyses and lesion experiments show that distinct combinations of sensory neurons function at different concentrations of the odorant; AWC and ASH sensory neurons have critical roles for attraction to or avoidance of the odorant, respectively. Moreover, we found that AWC neurons respond to only lower concentrations of the odorant, whereas ASH neurons respond to only higher concentrations of odorant. Hence, our study suggests that odour concentration coding in C. elegans mostly conforms to the labelled-line principle where distinct neurons respond to distinct stimuli. PMID:22415830

Yoshida, Kazushi; Hirotsu, Takaaki; Tagawa, Takanobu; Oda, Shigekazu; Wakabayashi, Tokumitsu; Iino, Yuichi; Ishihara, Takeshi

2012-03-13

175

Caenorhabditis elegans as a model organism to study APP function  

PubMed Central

The brains of Alzheimer's disease patients show an increased number of senile plaques compared with normal patients. The major component of the plaques is the ?-amyloid peptide, a cleavage product of the amyloid precursor protein (APP). Although the processing of APP has been well-described, the physiological functions of APP and its cleavage products remain unclear. This article reviews the multifunctional roles of an APP orthologue, the C. elegans APL-1. Understanding the function of APL-1 may provide insights into the functions and signaling pathways of human APP. In addition, the physiological effects of introducing human ?-amyloid peptide into C. elegans are also reviewed. The C. elegans system provides a powerful genetic model to identify genes regulating the molecular mechanisms underlying intracellular ?-amyloid peptide accumulation.

Ewald, Collin Y.; Li, Chris

2013-01-01

176

Relativistic correction to J/? and \\varUpsilon pair production  

NASA Astrophysics Data System (ADS)

The relativistic corrections to the productions of double J/?, double \\varUpsilon , and J/? + \\varUpsilon at the Tevatron and the LHC were investigated within the frame of non-relativistic QCD. The ratios of short distance coefficients between relativistic correction and leading order result for color singlet and color octet states in large p T limit are approximately -1, -11 /3, respectively, for pair production. And for J/? + \\varUpsilon process the ratio is -11 /6 for the J/? color octet channel and -11 /6 for the \\varUpsilon color octet channel. The K factors of next-to-leading order in v 2 for color singlet and color octet double J/? production are 0.77 and 0.16 at large p T region with adopting v 2 = 0.23. The contribution from the color-octet channel is depressed by the relativistic correction heavily and is negligible at the most p T region comparing with the color-singlet contribution for the J/? pair production. So we conclude the J/? pair production is no longer a nice platform to check the color-octet mechanism. On the other hand, relativistic corrections show limited to affect the coloroctet cross section for the J/? + \\varUpsilon process and this process can still be a probe to check color-octet mechanism. Also our results show that the single parton scattering model may be enough to explain the LHCb data for the J/? pair production.

Li, Yi-Jie; Xu, Guang-Zhi; Liu, Kui-Yong; Zhang, Yu-Jie

2013-07-01

177

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.

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

2009-01-01

178

Proteomic Study and Marker Protein Identification of Caenorhabditis elegans Lipid Droplets*  

PubMed Central

Lipid droplets (LDs) are a neutral lipid storage organelle that is conserved across almost all species. Many metabolic syndromes are directly linked to the over-storage of neutral lipids in LDs. The study of LDs in Caenorhabditis elegans (C. elegans) has been difficult because of the lack of specific LD marker proteins. Here we report the purification and proteomic analysis of C. elegans lipid droplets for the first time. We identified 306 proteins, 63% of these proteins were previously known to be LD-proteins, suggesting a similarity between mammalian and C. elegans LDs. Using morphological and biochemical analyses, we show that short-chain dehydrogenase, DHS-3 is almost exclusively localized on C. elegans LDs, indicating that it can be used as a LD marker protein in C. elegans. These results will facilitate further mechanistic studies of LDs in this powerful genetic system, C. elegans.

Zhang, Peng; Na, Huimin; Liu, Zhenglong; Zhang, Shuyan; Xue, Peng; Chen, Yong; Pu, Jing; Peng, Gong; Huang, Xun; Yang, Fuquan; Xie, Zhensheng; Xu, Tao; Xu, Pingyong; Ou, Guangshuo; Zhang, Shaobing O.; Liu, Pingsheng

2012-01-01

179

Assessing behavioral toxicity with Caenorhabditis elegans.  

PubMed

Behavior, even in simple metazoans, depends upon integrated processes at the subcellular, cellular, and organismal level, and thus is susceptible to disruption by a broad spectrum of chemicals. Locomotor behavior (movement) of the small free-living nematode Caenorhabditis elegans has proven to be useful in assessing toxicity. Recently reported observations suggest that behavioral change (reduced movement) occurs after 4 h of exposure to heavy metals, and that with abbreviated exposure, the concentration-response relationship for Pb (a known neurotoxic metal) differs from that for Cu. In this study, movement was evaluated after 4-h exposures for nine compounds from three chemical classes: organic pesticides, organic solvents, and heavy metals. Concentration-dependent reduction of movement was observed for all test compounds with the exception of mebendazole, for which test concentrations were limited by solubility. Within each chemical class, movement was more sensitive to the neurotoxic compounds than to substances not believed to be neurotoxic, as evidenced by behavioral effective concentration to reduce average worm movement to 50% of the control movement values (e.g., levamisole and chlorpyrifos < mebendazole, ethanol and acetone < dimethylsulfoxide, and Pb and Al < Cu). These observations are discussed as they relate to the use of acute behavioral tests in assessing general chemical toxicity, and the enhanced value of 4-h testing for the detection of neural toxicants. PMID:15180374

Anderson, Gary L; Cole, Russell D; Williams, Phillip L

2004-05-01

180

Epigenetic memory of longevity in Caenorhabditis elegans  

PubMed Central

A recent study by Greer et al. in the nematode C. elegans has shown transgenerational epigenetic inheritance of longevity in the descendants of worms deficient for subunits of a complex responsible for histone H3 lysine 4 trimethylation (H3K4me3). In this commentary, we discuss the implications of this epigenetic memory of longevity and the potential mechanisms underlying this phenomenon. The transgenerational inheritance of longevity could result from heritable depletion of H3K4me3 at particular aging-regulating gene loci that would only be progressively replenished. The epigenetic memory of longevity could also be explained by the transgenerational transmission of other molecules, for example other proteins or non-coding RNAs. The discovery of an epigenetic memory of longevity in worms raises the intriguing possibility that environmental cues modulating longevity in ancestors might affect subsequent generations in a non-Mendelian manner. Another remaining intriguing question is whether transgenerational inheritance of longevity also exists in other species, including mammals.

Benayoun, Berenice A.; Brunet, Anne

2012-01-01

181

The neurexin superfamily of Caenorhabditis elegans.  

PubMed

The neurexin superfamily is a group of transmembrane molecules mediating cell-cell contacts and generating specialized membranous domains in polarized epithelial and nerves cells. We describe here the domain organization and expression of the entire, core neurexin superfamily in the nematode Caenorhabditis elegans, which is composed of three family members. One of the superfamily members, nrx-1, is an ortholog of vertebrate neurexin, the other two, itx-1 and nlr-1, are orthologs of the Caspr subfamily of neurexin-like genes. Based on reporter gene analysis, we find that nrx-1 is exclusively expressed in most if not all cells of the nervous system and localizes to presynaptic specializations. itx-1 and nrx-1 reporter genes are expressed in non-overlapping patterns within and outside the nervous system. ITX-1 protein co-localizes with ?-G-spectrin to a subapical domain within intestinal cells. These studies provide a starting point for further functional analysis of this family of proteins. PMID:21055481

Haklai-Topper, Liat; Soutschek, Jürgen; Sabanay, Helena; Scheel, Jochen; Hobert, Oliver; Peles, Elior

2010-11-03

182

Caenorhabditis elegans vulval cell fate patterning.  

PubMed

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. PMID:22871570

Félix, Marie-Anne

2012-08-07

183

A circuit for navigation in Caenorhabditis elegans.  

PubMed

Caenorhabditis elegans explores its environment by interrupting its forward movement with occasional turns and reversals. Turns and reversals occur at stable frequencies but irregular intervals, producing probabilistic exploratory behaviors. Here we dissect the roles of individual sensory neurons, interneurons, and motor neurons in exploratory behaviors under different conditions. After animals are removed from bacterial food, they initiate a local search behavior consisting of reversals and deep omega-shaped turns triggered by AWC olfactory neurons, ASK gustatory neurons, and AIB interneurons. Over the following 30 min, the animals disperse as reversals and omega turns are suppressed by ASI gustatory neurons and AIY interneurons. Interneurons and motor neurons downstream of AIB and AIY encode specific aspects of reversal and turn frequency, amplitude, and directionality. SMD motor neurons help encode the steep amplitude of omega turns, RIV motor neurons specify the ventral bias of turns that follow a reversal, and SMB motor neurons set the amplitude of sinusoidal movement. Many of these sensory neurons, interneurons, and motor neurons are also implicated in chemotaxis and thermotaxis. Thus, this circuit may represent a common substrate for multiple navigation behaviors. PMID:15689400

Gray, Jesse M; Hill, Joseph J; Bargmann, Cornelia I

2005-02-02

184

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.

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

2007-01-01

185

A circuit for navigation in Caenorhabditis elegans  

PubMed Central

Caenorhabditis elegans explores its environment by interrupting its forward movement with occasional turns and reversals. Turns and reversals occur at stable frequencies but irregular intervals, producing probabilistic exploratory behaviors. Here we dissect the roles of individual sensory neurons, interneurons, and motor neurons in exploratory behaviors under different conditions. After animals are removed from bacterial food, they initiate a local search behavior consisting of reversals and deep omega-shaped turns triggered by AWC olfactory neurons, ASK gustatory neurons, and AIB interneurons. Over the following 30 min, the animals disperse as reversals and omega turns are suppressed by ASI gustatory neurons and AIY interneurons. Interneurons and motor neurons downstream of AIB and AIY encode specific aspects of reversal and turn frequency, amplitude, and directionality. SMD motor neurons help encode the steep amplitude of omega turns, RIV motor neurons specify the ventral bias of turns that follow a reversal, and SMB motor neurons set the amplitude of sinusoidal movement. Many of these sensory neurons, interneurons, and motor neurons are also implicated in chemotaxis and thermotaxis. Thus, this circuit may represent a common substrate for multiple navigation behaviors.

Gray, Jesse M.; Hill, Joseph J.; Bargmann, Cornelia I.

2005-01-01

186

The Landscape of C. elegans 3?UTRs  

PubMed Central

Three-prime untranslated regions (3?UTRs) of metazoan messenger RNAs (mRNAs) contain numerous regulatory elements, yet remain largely uncharacterized. Using polyA capture, 3? rapid amplification of complementary DNA (cDNA) ends, full-length cDNAs, and RNA-seq, we defined ?26,000 distinct 3?UTRs in Caenorhabditis elegans for ?85% of the 18,328 experimentally supported protein-coding genes and revised ?40% of gene models. Alternative 3?UTR isoforms are frequent, often differentially expressed during development. Average 3?UTR length decreases with animal age. Surprisingly, no polyadenylation signal (PAS) was detected for 13% of polyadenylation sites, predominantly among shorter alternative isoforms. Trans-spliced (versus non–trans-spliced) mRNAs possess longer 3?UTRs and frequently contain no PAS or variant PAS. We identified conserved 3?UTR motifs, isoform-specific predicted microRNA target sites, and polyadenylation of most histone genes. Our data reveal a rich complexity of 3?UTRs, both genome-wide and throughout development.

Mangone, Marco; Manoharan, Arun Prasad; Thierry-Mieg, Danielle; Thierry-Mieg, Jean; Han, Ting; Mackowiak, Sebastian D.; Mis, Emily; Zegar, Charles; Gutwein, Michelle R.; Khivansara, Vishal; Attie, Oliver; Chen, Kevin; Salehi-Ashtiani, Kourosh; Vidal, Marc; Harkins, Timothy T.; Bouffard, Pascal; Suzuki, Yutaka; Sugano, Sumio; Kohara, Yuji; Rajewsky, Nikolaus; Piano, Fabio; Gunsalus, Kristin C.; Kim, John K.

2011-01-01

187

ASI regulates satiety quiescence in C. elegans.  

PubMed

In Caenorhabditis elegans, satiety quiescence mimics behavioral aspects of satiety and postprandial sleep in mammals. On the basis of calcium-imaging, genetics, and behavioral studies, here we report that a pair of amphid neurons, ASI, is activated by nutrition and regulates worms' behavioral states specifically promoting satiety quiescence; ASI inhibits the switch from quiescence to dwelling (a browsing state) and accelerates the switch from dwelling to quiescence. The canonical TGF? pathway, whose ligand is released from ASI, regulates satiety quiescence. The mutants of a ligand, a receptor and SMADs in the TGF? pathway all eat more and show less quiescence than wild-type. The TGF? receptor in downstream neurons RIM and RIC is sufficient for worms to exhibit satiety quiescence, suggesting neuronal connection from ASI to RIM and RIC is essential for feeding regulation through the TGF? pathway. ASI also regulates satiety quiescence partly through cGMP signaling; restoring cGMP signaling in ASI rescues the satiety quiescence defect of cGMP signaling mutants. From these results, we propose that TGF? and cGMP pathways in ASI connect nutritional status to promotion of satiety quiescence, a sleep-like behavioral state. PMID:23739968

Gallagher, Thomas; Kim, Jeongho; Oldenbroek, Marieke; Kerr, Rex; You, Young-Jai

2013-06-01

188

Achieving immortality in the C. elegans germline.  

PubMed

Germline immortality is a topic that has intrigued theoretical biologists interested in aging for over a century. The germ cell lineage can be passed from one generation to the next, indefinitely. In contrast, somatic cells are typically only needed for a single generation and are then discarded. Germ cells may, therefore, harbor rejuvenation mechanisms that enable them to proliferate for eons. Such processes are thought to be either absent from or down-regulated in somatic cells, although cell non-autonomous forms of rejuvenation are formally possible. A thorough description of mechanisms that foster eternal youth in germ cells is lacking. The mysteries of germline immortality are being addressed in the nematode Caenorhabditis elegans by studying mutants that reproduce normally for several generations but eventually become sterile. The mortal germline mutants probably become sterile as a consequence of accumulating various forms of heritable cellular damage. Such mutants are abundant, indicating that several different biochemical pathways are required to rejuvenate the germline. Thus, forward genetics should help to define mechanisms that enable the germline to achieve immortality. PMID:15619471

Smelick, Chris; Ahmed, Shawn

2004-12-10

189

Rhino-orbitocerebral mucormycosis caused by Apophysomyces elegans.  

PubMed

Rhino-orbitocerebral mucormycosis (ROCM) caused by more common zygomycetes (e.g., Mucor) is known to cause rapidly fatal infections in immunocompromised patients. Apophysomyces elegans is an emerging zygomycete that has been reported to cause invasive cutaneous and rhino-orbitocerebral infections in immunocompetent individuals. Limited data exist describing the syndrome of ROCM caused by A. elegans. We describe a recent case and performed a comprehensive literature review to delineate the clinical characteristics of ROCM caused by A. elegans. Our case is a 50-year-old man with diabetes mellitus who presented with facial pain and right eye proptosis. Endoscopic sinus sampling revealed A. elegans. He was treated with liposomal amphotericin B and multiple debridements, with no disease on 1.5-year follow-up examination. Seven cases were identified on literature review, including the present case. Most patients (86%) were male, with a mean age of 40 years. Most patients (71%) did not have predisposing medical conditions. Three patients had predisposing head trauma. All presented with facial and/or periorbital pain. All had magnetic resonance imaging or computed tomography of the head showing intraorbital and/or sinus inflammation. Diagnosis was confirmed by histopathology and deep tissue culture in all cases. All patients required eye exenteration and extensive surgical debridement, in addition to intravenous amphotericin B. Six of the seven patients (86%) recovered. ROCM caused by A. elegans is rarely reported in the literature. Most such infections occurred in immunocompetent patients, often after facial trauma. Survival in ROCM caused by A. elegans is favorable in reported cases, with prompt surgical debridement and antifungal therapy. PMID:16517873

Liang, Kimberly P; Tleyjeh, Imad M; Wilson, Walter R; Roberts, Glenn D; Temesgen, Zelalem

2006-03-01

190

Staphylococcal Biofilm Exopolysaccharide Protects against Caenorhabditis elegans Immune Defenses  

PubMed Central

Staphylococcus epidermidis and Staphylococcus aureus are leading causes of hospital-acquired infections that have become increasingly difficult to treat due to the prevalence of antibiotic resistance in these organisms. The ability of staphylococci to produce biofilm is an important virulence mechanism that allows bacteria both to adhere to living and artificial surfaces and to resist host immune factors and antibiotics. Here, we show that the icaADBC locus, which synthesizes the biofilm-associated polysaccharide intercellular adhesin (PIA) in staphylococci, is required for the formation of a lethal S. epidermidis infection in the intestine of the model nematode Caenorhabditis elegans. Susceptibility to S. epidermidis infection is influenced by mutation of the C. elegans PMK-1 p38 mitogen-activated protein (MAP) kinase or DAF-2 insulin-signaling pathways. Loss of PIA production abrogates nematocidal activity and leads to reduced bacterial accumulation in the C. elegans intestine, while overexpression of the icaADBC locus in S. aureus augments virulence towards nematodes. PIA-producing S. epidermidis has a significant survival advantage over ica-deficient S. epidermidis within the intestinal tract of wild-type C. elegans, but not in immunocompromised nematodes harboring a loss-of-function mutation in the p38 MAP kinase pathway gene sek-1. Moreover, sek-1 and pmk-1 mutants are equally sensitive to wild-type and icaADBC-deficient S. epidermidis. These results suggest that biofilm exopolysaccharide enhances virulence by playing an immunoprotective role during colonization of the C. elegans intestine. These studies demonstrate that C. elegans can serve as a simple animal model for studying host–pathogen interactions involving staphylococcal biofilm exopolysaccharide and suggest that the protective activity of biofilm matrix represents an ancient conserved function for resisting predation.

Begun, Jakob; Gaiani, Jessica M; Rohde, Holger; Mack, Dietrich; Calderwood, Stephen B; Ausubel, Frederick M; Sifri, Costi D

2007-01-01

191

Regulatory elements of Caenorhabditis elegans ribosomal protein genes  

PubMed Central

Background Ribosomal protein genes (RPGs) are essential, tightly regulated, and highly expressed during embryonic development and cell growth. Even though their protein sequences are strongly conserved, their mechanism of regulation is not conserved across yeast, Drosophila, and vertebrates. A recent investigation of genomic sequences conserved across both nematode species and associated with different gene groups indicated the existence of several elements in the upstream regions of C. elegans RPGs, providing a new insight regarding the regulation of these genes in C. elegans. Results In this study, we performed an in-depth examination of C. elegans RPG regulation and found nine highly conserved motifs in the upstream regions of C. elegans RPGs using the motif discovery algorithm DME. Four motifs were partially similar to transcription factor binding sites from C. elegans, Drosophila, yeast, and human. One pair of these motifs was found to co-occur in the upstream regions of 250 transcripts including 22 RPGs. The distance between the two motifs displayed a complex frequency pattern that was related to their relative orientation. We tested the impact of three of these motifs on the expression of rpl-2 using a series of reporter gene constructs and showed that all three motifs are necessary to maintain the high natural expression level of this gene. One of the motifs was similar to the binding site of an orthologue of POP-1, and we showed that RNAi knockdown of pop-1 impacts the expression of rpl-2. We further determined the transcription start site of rpl-2 by 5’ RACE and found that the motifs lie 40–90 bases upstream of the start site. We also found evidence that a noncoding RNA, contained within the outron of rpl-2, is co-transcribed with rpl-2 and cleaved during trans-splicing. Conclusions Our results indicate that C. elegans RPGs are regulated by a complex novel series of regulatory elements that is evolutionarily distinct from those of all other species examined up until now.

2012-01-01

192

Comparison of Caenorhabditis elegans NLP peptides with arthropod neuropeptides.  

PubMed

Neuropeptides are small messenger molecules that can be found in all metazoans, where they govern a diverse array of physiological processes. Because neuropeptides seem to be conserved among pest species, selected peptides can be considered as attractive targets for drug discovery. Much can be learned from the model system Caenorhabditis elegans because of the availability of a sequenced genome and state-of-the-art postgenomic technologies that enable characterization of endogenous peptides derived from neuropeptide-like protein (NLP) precursors. Here, we provide an overview of the NLP peptide family in C. elegans and discuss their resemblance with arthropod neuropeptides and their relevance for anthelmintic discovery. PMID:19269897

Husson, Steven J; Lindemans, Marleen; Janssen, Tom; Schoofs, Liliane

2009-03-09

193

Sperm and Oocyte Communication Mechanisms Controlling C. elegans Fertility  

PubMed Central

During sexual reproduction in many species, sperm and oocyte secrete diffusible signaling molecules to help orchestrate the biological symphony of fertilization. In the Caenorhabditis elegans gonad, bidirectional signaling between sperm and oocyte is important for guiding sperm to the fertilization site and inducing oocyte maturation. The molecular mechanisms that regulate sperm guidance and oocyte maturation are being delineated. Unexpectedly, these mechanisms are providing insight into human diseases, such as amyotrophic lateral sclerosis, spinal muscular atrophy, and cancer. Here we review sperm and oocyte communication in C. elegans and discuss relationships to human disorders.

Han, Sung Min; Cottee, Pauline A.; Miller, Michael A.

2010-01-01

194

Production & formulation of Bacillus thuringiensis var. israelensis & B. sphaericus 1593.  

PubMed

Three fermentation media each for bulk growth of B. thuringiensis var. israelensis and B. sphaericus 1593 were formulated using defatted groundnut cake (Arachis hypogea) as the first nitrogen source and gram flour (Cicer arientinum), soy bean (Glycine max) and defatted milk powder as the second nitrogen source. Medium containing gram flour showed highest toxicity (14.45 micrograms/l) in case of B. thuringiensis var. israelensis whereas medium containing milk powder was found to be highly toxic with B. sphaericus 1593 (51.39 micrograms/l). Sustained release floating pellet formulations of B. thuringiensis var. israelensis and B. sphaericus 1593 exhibited toxicity of 77 per cent and above for 42 days at a dose of 500 micrograms/l for 4th instar larvae of Culex pipiens quinquefasciatus Say. PMID:1778620

Desai, S Y; Shethna, Y I

1991-09-01

195

40 CFR 80.170 - Volumetric additive reconciliation (VAR), equipment calibration, and recordkeeping requirements.  

Code of Federal Regulations, 2013 CFR

...additive reconciliation (VAR), equipment calibration, and recordkeeping requirements...additive reconciliation (VAR), equipment calibration, and recordkeeping requirements...calendar half year, with the acceptable calibrations being no less than one hundred...

2013-07-01

196

Structural polymorphism and diversifying selection on the pregnancy malaria vaccine candidate VAR2CSA  

Microsoft Academic Search

VAR2CSA is the main candidate for a pregnancy malaria vaccine, but vaccine development may be complicated by sequence polymorphism. Here, we obtained partial or full-length var2CSA sequences from 106 parasites and applied novel computational methods and three-dimensional modeling to investigate VAR2CSA geographic variation and selection pressure. Our analysis reveals structural patterns of VAR2CSA sequence variation in which polymorphic sites group

Joseph Bockhorst; Fangli Lu; Joel H. Janes; Jon Keebler; Benoit Gamain; Philip Awadalla; Xin-zhuan Su; Ram Samudrala; Nebojsa Jojic; Joseph D. Smith

2007-01-01

197

Reevaluation of the biological status of Juniperus Deppeana var. sperryi Correll  

Microsoft Academic Search

Foliage and bark samples were collected from the tree that provided the type specimen forJuniperus deppeana var.sperryi Correll, as well as from trees from populations ofJ. pinchotii Sudw.,J. flacida Schl., andJ. deppeana Steud. var.deppeana. These four taxa were compared using terpenoid and morphological characters. The terpenoid data suggest thatJ. deppeana var.sperryi is most closely related toJ. deppeana var.deppeana; no evidence

Robert P. Adams

1973-01-01

198

Minimizing CVaR and VaR for a Portfolio of Derivatives  

Microsoft Academic Search

Value at risk (VaR) and conditional value at risk (CVaR) are the most frequently used risk measures in current risk management practice. As an alternative to VaR, CVaR is attractive since it is a coherent risk measure. We analyze the problem of computing the optimal VaR and CVaR portfolios. In particular, we illustrate that VaR and CVaR minimization problems for

Siddharth Alexander; Yuying Li; Y. Lic

2004-01-01

199

varDB: common ground for a shifting landscape  

PubMed Central

Antigenic variation is a phylogenetically widespread phenomenon thought to lead to survival benefits for the pathogen. Although governed by genetic mechanisms, antigenic variation is ultimately manifested in variant proteins. The varDB database is an attempt to gain an overview of common structures and functions of variant proteins related to enhanced survival. varDB provides a wealth of sequence data and several tools to facilitate their analysis, but current limitations preclude achievement of its full promise. A critique of this database and how it could serve the scientific community is provided here.

Allred, David R.; Barbet, Anthony F.; Barry, J. David; Deitsch, Kirk W.

2013-01-01

200

Comparative Developmental Expression Profiling of Two C. elegans Isolates  

Microsoft Academic Search

Gene expression is known to change during development and to vary among genetically diverse strains. Previous studies of temporal patterns of gene expression during C. elegans development were incomplete, and little is known about how these patterns change as a function of genetic background. We used microarrays that comprehensively cover known and predicted worm genes to compare the landscape of

Emily J. Capra; Sonja M. Skrovanek; Leonid Kruglyak; Xiaolin Wu

2008-01-01

201

The art and design of genetic screens: Caenorhabditis elegans  

Microsoft Academic Search

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,

Erik M. Jorgensen; Susan E. Mango

2002-01-01

202

Prednisone reduces muscle degeneration in dystrophin-deficient Caenorhabditis elegans  

Microsoft Academic Search

Duchenne muscular dystrophy is a degenerative muscular disease caused by mutations in the dystrophin gene. There is no curative treatment against Duchenne muscular dystrophy. In several countries, the steroid prednisone (or analogs) is prescribed as a palliative treatment. In the model animal Caenorhabditis elegans, mutations of the dys-1 dystrophin-like gene lead to a muscular degenerative phenotype when they are associated

Aurélie Gaud; Jean-Marc Simon; Thomas Witzel; Maité Carre-Pierrat; Camille G Wermuth; Laurent Ségalat

2004-01-01

203

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

204

The Caenorhabditis elegans Elongator Complex Regulates Neuronal ?-tubulin Acetylation  

Microsoft Academic Search

Although acetylated ?-tubulin is known to be a marker of stable microtubules in neurons, precise factors that regulate ?-tubulin acetylation are, to date, largely unknown. Therefore, a genetic screen was employed in the nematode Caenorhabditis elegans that identified the Elongator complex as a possible regulator of ?-tubulin acetylation. Detailed characterization of mutant animals revealed that the acetyltransferase activity of the

Jachen A. Solinger; Roberta Paolinelli; Holger Klöß; Francesco Berlanda Scorza; Stefano Marchesi; Ursula Sauder; Dai Mitsushima; Fabrizio Capuani; Stephen R. Stürzenbaum; Giuseppe Cassata

2010-01-01

205

The worm has turned - microbial virulence modeled in Caenorhabditis elegans  

Microsoft Academic Search

The nematode Caenorhabditis elegans is emerging as a facile and economical model host for the study of evolu- tionarily conserved mechanisms of microbial patho- genesis and innate immunity. A rapidly growing number of human and animal microbial pathogens have been shown to injure and kill nematodes. In many cases, microbial genes known to be important for full virulence in mammalian

Costi D. Sifri; Jakob Begun; Frederick M. Ausubel

2005-01-01

206

An antidepressant that extends lifespan in adult Caenorhabditis elegans  

Microsoft Academic Search

The mechanisms that determine the lifespan of an organism are still largely a mystery. One goal of ageing research is to find drugs that would increase lifespan and vitality when given to an adult animal. To this end, we tested 88,000 chemicals for the ability to extend the lifespan of adult Caenorhabditis elegans nematodes. Here we report that a drug

Michael Petrascheck; Xiaolan Ye; Linda B. Buck

2007-01-01

207

An Elegant Mind: Learning and Memory in "Caenorhabditis elegans"  

ERIC Educational Resources Information Center

|This article reviews the literature on learning and memory in the soil-dwelling nematode "Caenorhabditis elegans." Paradigms include nonassociative learning, associative learning, and imprinting, as worms have been shown to habituate to mechanical and chemical stimuli, as well as learn the smells, tastes, temperatures, and oxygen levels that…

Ardiel, Evan L.; Rankin, Catharine H.

2010-01-01

208

Asexual Reproduction in Pygospio elegans Claparède (Polychæta sedentaria)  

Microsoft Academic Search

DURING the course of an ecological investigation of the polychæte annelid Pygospio elegans Clap., a remarkable mode of asexual reproduction was noticed. The species were collected at the small island of Vorsø in the Horsensfjord (East Jutland, Denmark) and the phenomenon was first observed in April 1949.

Erik Rasmussen

1953-01-01

209

Identification of Pseudomonas aeruginosa Phenazines that Kill Caenorhabditis elegans  

PubMed Central

Pathogenic microbes employ a variety of methods to overcome host defenses, including the production and dispersal of molecules that are toxic to their hosts. Pseudomonas aeruginosa, a Gram-negative bacterium, is a pathogen of a diverse variety of hosts including mammals and the nematode Caenorhabditis elegans. In this study, we identify three small molecules in the phenazine class that are produced by P. aeruginosa strain PA14 that are toxic to C. elegans. We demonstrate that 1-hydroxyphenazine, phenazine-1-carboxylic acid, and pyocyanin are capable of killing nematodes in a matter of hours. 1-hydroxyphenazine is toxic over a wide pH range, whereas the toxicities of phenazine-1-carboxylic acid and pyocyanin are pH-dependent at non-overlapping pH ranges. We found that acidification of the growth medium by PA14 activates the toxicity of phenazine-1-carboxylic acid, which is the primary toxic agent towards C. elegans in our assay. Pyocyanin is not toxic under acidic conditions and 1-hydroxyphenazine is produced at concentrations too low to kill C. elegans. These results suggest a role for phenazine-1-carboxylic acid in mammalian pathogenesis because PA14 mutants deficient in phenazine production have been shown to be defective in pathogenesis in mice. More generally, these data demonstrate how diversity within a class of metabolites could affect bacterial toxicity in different environmental niches.

Cezairliyan, Brent; Vinayavekhin, Nawaporn; Grenfell-Lee, Daniel; Yuen, Grace J.; Saghatelian, Alan; Ausubel, Frederick M.

2013-01-01

210

A Test for Epistasis Among Induced Mutations in Caenorhabditis elegans  

Microsoft Academic Search

Synergistic epistasis, in which deleterious mutations tend to magnify each other's effects, is a necessary component of the mutational deterministic hypothesis for the maintenance of sexual production. We tested for epistasis for life-history traits in the soil nematode Caenorhabditis elegans by inducing mutations in two genetic backgrounds: a wild-type strain and a set of genetically loaded lines that contain large

Andrew D. Peters; Peter D. Keightley

2000-01-01

211

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

212

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).

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

2012-01-01

213

An Engineering Approach to Extending Lifespan in C. elegans  

Microsoft Academic Search

We have taken an engineering approach to extending the lifespan of Caenorhabditis elegans. Aging stands out as a complex trait, because events that occur in old animals are not under strong natural selection. As a result, lifespan can be lengthened rationally using bioengineering to modulate gene expression or to add exogenous components. Here, we engineered longer lifespan by expressing genes

Dror Sagi; Stuart K. Kim

2012-01-01

214

Sex-Related Differences in Crossing Over in Caenorhabditis elegans  

Microsoft Academic Search

In the nematode Caenorhabditis elegans, hermaphrodite recombination has been characterized and is the basis of the genetic map used in this organism. In this study we have examined male recombination on linkage group I and have found it to be approximately one-third less than that observed in the hermaphrodite. This decrease was interval-dependent and nonuniform. We observed less recombination in

Monique-Claire Zetka; Ann M. Rose

215

Caenorhabditis elegans Intersectin: A Synaptic Protein Regulating Neurotransmission  

Microsoft Academic Search

Intersectin is a multifunctional protein that interacts with components of the endocytic and exocytic pathways, and it is also involved in the control of actin dynamics. Drosophila intersectin is required for viability, synaptic development, and synaptic vesicle recycling. Here, we report the characterization of intersectin function in Caenorhabditis elegans. Nema- tode intersectin (ITSN-1) is expressed in the nervous system, and

Simon Rose; Maria Grazia Malabarba; Claudia Krag; Anna Schultz; Hanako Tsushima; Pier Paolo Di Fiore; Anna Elisabetta Salcini

2007-01-01

216

The major gut esterase locus in the nematode Caenorhabditis elegans  

Microsoft Academic Search

Mutations in the major gut esterase of the nematode Caenorhabditis elegans have been induced by ethylmethane sulfonate and detected by isoelectric focusing. The gut esterase locus, denoted ges-1, maps less than 0.3 map units to the right of the unc-60 locus, at the left end of chromosome V.

James D. McGhee; Denise A. Cottrell

1986-01-01

217

The evolutionary role of males in C. elegans  

PubMed Central

Although the nematode worm Caenorhabditis elegans reproduces primarily as a self-fertilizing hermaphrodite, males are maintained in natural populations at low frequency. In this commentary, I discuss the evolutionary forces that maintain males and the role males might play in this mating system.

Chasnov, Jeffrey R.

2013-01-01

218

Allyl isothiocyanate induced stress response in Caenorhabditis elegans  

PubMed Central

Background Allyl isothiocyanate (AITC) from mustard is cytotoxic; however the mechanism of its toxicity is unknown. We examined the effects of AITC on heat shock protein (HSP) 70 expression in Caenorhabditis elegans. We also examined factors affecting the production of AITC from its precursor, sinigrin, a glucosinolate, in ground Brassica juncea cv. Vulcan seed as mustard has some potential as a biopesticide. Findings An assay to determine the concentration of AITC in ground mustard seed was improved to allow the measurement of AITC release in the first minutes after exposure of ground mustard seed to water. Using this assay, we determined that temperatures above 67°C decreased sinigrin conversion to AITC in hydrated ground B. juncea seed. A pH near 6.0 was found to be necessary for AITC release. RT-qPCR revealed no significant change in HSP70A mRNA expression at low concentrations of AITC (< 0.1 ?M). However, treatment with higher concentrations (> 1.0 ?M) resulted in a four- to five-fold increase in expression. A HSP70 ELISA showed that AITC toxicity in C. elegans was ameliorated by the presence of ground seed from low sinigrin B. juncea cv. Arrid. Conclusions • AITC induced toxicity in C. elegans, as measured by HSP70 expression. • Conditions required for the conversion of sinigrin to AITC in ground B. juncea seed were determined. • The use of C. elegans as a bioassay to test AITC or mustard biopesticide efficacy is discussed.

2011-01-01

219

Whole-genome sequencing and variant discovery in C. elegans  

Microsoft Academic Search

Massively parallel sequencing instruments enable rapid and inexpensive DNA sequence data production. Because these instruments are new, their data require characterization with respect to accuracy and utility. To address this, we sequenced a Caernohabditis elegans N2 Bristol strain isolate using the Solexa Sequence Analyzer, and compared the reads to the reference genome to characterize the data and to evaluate coverage

LaDeana W Hillier; Gabor T Marth; Aaron R Quinlan; David Dooling; Ginger Fewell; Derek Barnett; Paul Fox; Jarret I Glasscock; Matthew Hickenbotham; Weichun Huang; Vincent J Magrini; Ryan J Richt; Sacha N Sander; Donald A Stewart; Michael Stromberg; Eric F Tsung; Todd Wylie; Tim Schedl; Richard K Wilson; Elaine R Mardis

2008-01-01

220

A metabolic signature of long life in Caenorhabditis elegans  

Microsoft Academic Search

BACKGROUND: Many Caenorhabditis elegans mutations increase longevity and much evidence suggests that they do so at least partly via changes in metabolism. However, up until now there has been no systematic investigation of how the metabolic networks of long-lived mutants differ from those of normal worms. Metabolomic technologies, that permit the analysis of many untargeted metabolites in parallel, now make

Silke Fuchs; Jacob G Bundy; Sarah K Davies; Jonathan M Viney; Jonathan S Swire; Armand M Leroi

2010-01-01

221

A Method for Culturing Embryonic C. elegans Cells.  

PubMed

C. elegans is a powerful model system, in which genetic and molecular techniques are easily applicable. Until recently though, techniques that require direct access to cells and isolation of specific cell types, could not be applied in C. elegans. This limitation was due to the fact that tissues are confined within a pressurized cuticle which is not easily digested by treatment with enzymes and/or detergents. Based on early pioneer work by Laird Bloom, Christensen and colleagues (1) developed a robust method for culturing C. elegans embryonic cells in large scale. Eggs are isolated from gravid adults by treatment with bleach/NaOH and subsequently treated with chitinase to remove the eggshells. Embryonic cells are then dissociated by manual pipetting and plated onto substrate-covered glass in serum-enriched media. Within 24 hr of isolation cells begin to differentiate by changing morphology and by expressing cell specific markers. C. elegans cells cultured using this method survive for up 2 weeks in vitro and have been used for electrophysiological, immunochemical, and imaging analyses as well as they have been sorted and used for microarray profiling. PMID:24084243

Sangaletti, Rachele; Bianchi, Laura

2013-09-21

222

Evaluation of Pesticide Toxicities with Differing Mechanisms Using Caenorhabditis elegans  

Microsoft Academic Search

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

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

2009-01-01

223

Ecotoxicological evaluation of chlorpyrifos exposure on the nematode Caenorhabditis elegans  

Microsoft Academic Search

To investigate the effects of chlorpyrifos (CP), an organophosphorus insecticide, on the soil nematode Caenorhabditis elegans, the toxicity of the insecticide on the molecular, biochemical, and physiological levels were investigated upon sublethal exposure, and an acute toxicity test was conducted using lethality as an endpoint. To assess the molecular-level effect, stress-related gene expression was investigated, and the neurotoxicity indicator, acetylcholinesterase

Ji-Yeon Roh; Jinhee Choi

2008-01-01

224

Toxicities of microcystin LR on caenorhabditis elegans and their offspring  

Microsoft Academic Search

In the present study, we investigated the toxicities of microcystin LR (MC LR) to Caenorhabditis elegans and the transferability of these toxicities from parents to offspring. Our results showed that the endpoints of life span and body length were not sensitive to low concentration of MCLR exposure (< 10 ?g\\/L). However, MCLR exposure can lead to serious reproduction and locomotion

Xiaoguo Chen; Fan Hu; Weicheng Zhang; Yue Hu; Ruiting Yan; Bangding Xiao

2011-01-01

225

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

2011-03-24

226

Histidine Protects Against Zinc and Nickel Toxicity in Caenorhabditis elegans  

PubMed Central

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.

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

2011-01-01

227

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

228

Dissecting a circuit for olfactory behaviour in Caenorhabditis elegans  

Microsoft Academic Search

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

Sreekanth H. Chalasani; Nikos Chronis; Makoto Tsunozaki; Jesse M. Gray; Daniel Ramot; Miriam B. Goodman; Cornelia I. Bargmann

2007-01-01

229

The Structure of the Ventral Nerve Cord of Caenorhabditis elegans  

Microsoft Academic Search

The nervous system of Caenorhabditis elegans is arranged as a series of fibre bundles which run along internal hypodermal ridges. Most of the sensory integration takes place in a ring of nerve fibres which is wrapped round the pharynx in the head. The body muscles in the head are innervated by motor neurones in this nerve ring while those in

J. G. White; Eileen Southgate; J. N. Thomson; S. Brenner

1976-01-01

230

A gene expression fingerprint of C. elegans embryonic motor neurons  

Microsoft Academic Search

BACKGROUND: Differential gene expression specifies the highly diverse cell types that constitute the nervous system. With its sequenced genome and simple, well-defined neuroanatomy, the nematode C. elegans is a useful model system in which to correlate gene expression with neuron identity. The UNC-4 transcription factor is expressed in thirteen embryonic motor neurons where it specifies axonal morphology and synaptic function.

Rebecca M Fox; Stephen E Von Stetina; Susan J Barlow; Christian Shaffer; Kellen L Olszewski; Jason H Moore; Denis Dupuy; Marc Vidal; David M Miller III

2005-01-01

231

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

232

Cell lineage and cell death: Caenorhabditis elegans and cancer research  

Microsoft Academic Search

Cancer is a complex disease in which cells have circumvented normal restraints on tissue growth and have acquired complex abnormalities in their genomes, posing a considerable challenge to identifying the pathways and mechanisms that drive fundamental aspects of the malignant phenotype. Genetic analyses of the normal development of the nematode Caenorhabditis elegans have revealed evolutionarily conserved mechanisms through which individual

Malia B. Potts; Scott Cameron

2010-01-01

233

Lethal Paralysis of Caenorhabditis elegans by Pseudomonas aeruginosa  

Microsoft Academic Search

Identification of host factors that interact with pathogens is crucial to an understanding of infectious disease, but direct screening for host mutations to aid in this task is not feasible in mammals. The nematode Caenorhabditis elegans is a genetically tractable alternative for investigating the pathogenic bacterium Pseudomonas aeruginosa. A P. aeruginosa toxin, produced at high cell density under control of

Creg Darby; Christine L. Cosma; James H. Thomas; Colin Manoil

1999-01-01

234

Pseudomonas aeruginosa PAO1 Kills Caenorhabditis elegans by Cyanide Poisoning  

Microsoft Academic Search

In this report we describe experiments to investigate a simple virulence model in which Pseudomonas aerugi- nosa 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

LARRY A. GALLAGHER; COLIN MANOIL

2001-01-01

235

Transgenic C. elegans as a Model in Alzheimer's Research  

Microsoft Academic Search

Alzheimer's disease (AD) has been associated with aggregation of ?-amyloid peptide (A?) and cell death in the brain. Using various models, such as the nematode Caenorhabditis elegans, the fruit fly Drosophila melanogaster and the mouse Mus musculus, investigators have attempted to imitate the pathology process of AD for better understanding of the cellular mechanisms and for possible therapeutic intervention. Among

Yanjue Wu; Yuan Luo

2005-01-01

236

ROS in aging Caenorhabditis elegans: damage or signaling?  

PubMed

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

2012-08-15

237

Appetitive response of the nematode Caenorhabditis elegans to oxygen  

Microsoft Academic Search

Using a technique of recording the behavior of individual nematodes during exposure to various solutions, it was demonstrated thatC. elegans made more reversal behaviors after transfer to solutions of lower oxygen tension than higher. The response was stronger after the first hour in the apparatus than initially. This change was not dependent on reduced oxygen availability during the initial period.

David B. Dusenbery

1980-01-01

238

ANALYSIS OF GENETIC MOSAICS OF THE NEMATODE CAENORHABDITIS ELEGANS  

Microsoft Academic Search

A new method for producing genetic mosaics, which involves the spontaneous somatic loss of free chromosome fragments, is demonstrated. Four genes that affect the behavior of C. elegans were studied in mosaic animals. The analysis was greatly aided by the fact that the complete cell lineage of wild-type animals is known. Two of the mutant genes affect certain sensory responses

ROBERT K. HERMAN

239

Computational Rules for Chemotaxis in the Nematode C. elegans  

Microsoft Academic Search

We derive a linear neural network model of the chemotaxis control circuit in the nematode Caenorhab- ditis elegans and demonstrate that this model is capable of producing nematodelike chemotaxis. By expanding the analytic solution for the network output in time-derivatives of the network input, we extract simple computational rules that reveal how the model network controls chemotaxis. Based on these

Thomas C. Ferrée; Shawn R. Lockery

1999-01-01

240

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

241

Paradigms for Pharmacological Characterization of C. elegans Synaptic Transmission Mutants  

PubMed Central

The nematode, Caenorhabditis elegans, has become an expedient model for studying neurotransmission. C. elegans is unique among animal models, as the anatomy and connectivity of its nervous system has been determined from electron micrographs and refined by pharmacological assays. In this video, we describe how two complementary neural stimulants, an acetylcholinesterase inhibitor, called aldicarb, and a gamma-aminobutyric acid (GABA) receptor antagonist, called pentylenetetrazole (PTZ), may be employed to specifically characterize signaling at C. elegans neuromuscular junctions (NMJs) and facilitate our understanding of antagonistic neural circuits. Of 302 C. elegans neurons, nineteen GABAergic D-type motor neurons innervate body wall muscles (BWMs), while four GABAergic neurons, called RMEs, innervate head muscles. Conversely, thirty-nine motor neurons express the excitatory neurotransmitter, acetylcholine (ACh), and antagonize GABA transmission at BWMs to coordinate locomotion. The antagonistic nature of GABAergic and cholinergic motor neurons at body wall NMJs was initially determined by laser ablation and later buttressed by aldicarb exposure. Acute aldicarb exposure results in a time-course or dose-responsive paralysis in wild-type worms. Yet, loss of excitatory ACh transmission confers resistance to aldicarb, as less ACh accumulates at worm NMJs, leading to less stimulation of BWMs. Resistance to aldicarb may be observed with ACh-specific or general synaptic function mutants. Consistent with antagonistic GABA and ACh transmission, loss of GABA transmission, or a failure to negatively regulate ACh release, confers hypersensitivity to aldicarb. Although aldicarb exposure has led to the isolation of numerous worm homologs of neurotransmission genes, aldicarb exposure alone cannot efficiently determine prevailing roles for genes and pathways in specific C. elegans motor neurons. For this purpose, we have introduced a complementary experimental approach, which uses PTZ. Neurotransmission mutants display clear phenotypes, distinct from aldicarb-induced paralysis, in response to PTZ. Wild-type worms, as well as mutants with specific inabilities to release or receive ACh, do not show apparent sensitivity to PTZ. However, GABA mutants, as well as general synaptic function mutants, display anterior convulsions in a time-course or dose-responsive manner. Mutants that cannot negatively regulate general neurotransmitter release and, thus, secrete excessive amounts of ACh onto BWMs, become paralyzed on PTZ. The PTZ-induced phenotypes of discrete mutant classes indicate that a complementary approach with aldicarb and PTZ exposure paradigms in C. elegans may accelerate our understanding of neurotransmission. Moreover, videos demonstrating how we perform pharmacological assays should establish consistent methods for C. elegans research.

Locke, Cody; Berry, Kalen; Kautu, Bwarenaba; Lee, Kyle; Caldwell, Kim; Caldwell, Guy

2008-01-01

242

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.

Rockman, Matthew V.; Kruglyak, Leonid

2009-01-01

243

Measuring Caenorhabditis elegans Life Span in 96 Well Microtiter Plates  

PubMed Central

Lifespan is a biological process regulated by several genetic pathways. One strategy to investigate the biology of aging is to study animals that harbor mutations in components of age-regulatory pathways. If these mutations perturb the function of the age-regulatory pathway and therefore alter the lifespan of the entire organism, they provide important mechanistic insights1-3. Another strategy to investigate the regulation of lifespan is to use small molecules to perturb age-regulatory pathways. To date, a number of molecules are known to extend lifespan in various model organisms and are used as tools to study the biology of aging4-16. The number of molecules identified thus far is small compared to the genetic "toolset" that is available to study the biology of aging. Caenorhabditis elegans is one of the principle models used to study aging because of its excellent genetics and short lifespan of three weeks. More recently, C.elegans has emerged as a model organism for phenotype based drug screens5,7,16-20 because of its small size and its ability to grow in microtiter plates. Here we present an assay to measure C.elegans lifespan in 96 well microtiter plates. The assay was developed and successfully used to screen large libraries for molecules that extend C.elegans lifespan7. The reliability of the assay was evaluated in multiple tests: first, by measuring the lifespan of wild type animals grown at different temperatures; second, by measuring the lifespan of mutants with altered lifespans; third, by measuring changes in lifespan in response to different concentrations of the antidepressant Mirtazepine. Mirtazepine has previously been shown to extend lifespan in C.elegans7. The results of these tests show that the assay is able to replicate previous findings from other assays and is quantitative. The microtiter format also makes this lifespan assay compatible with automated liquid handling systems and allows integration into automated platforms.

Solis, Gregory M.; Petrascheck, Michael

2011-01-01

244

Decline of nucleotide excision repair capacity in aging Caenorhabditis elegans  

PubMed Central

Background Caenorhabditis elegans is an important model for the study of DNA damage and repair related processes such as aging, neurodegeneration, and carcinogenesis. However, DNA repair is poorly characterized in this organism. We adapted a quantitative polymerase chain reaction assay to characterize repair of DNA damage induced by ultraviolet type C (UVC) radiation in C. elegans, and then tested whether DNA repair rates were affected by age in adults. Results UVC radiation induced lesions in young adult C. elegans, with a slope of 0.4 to 0.5 lesions per 10 kilobases of DNA per 100 J/m2, in both nuclear and mitochondrial targets. L1 and dauer larvae were more than fivefold more sensitive to lesion formation than were young adults. Nuclear repair kinetics in a well expressed nuclear gene were biphasic in nongravid adult nematodes: a faster, first order (half-life about 16 hours) phase lasting approximately 24 hours and resulting in removal of about 60% of the photoproducts was followed by a much slower phase. Repair in ten nuclear DNA regions was 15% and 50% higher in more actively transcribed regions in young and aging adults, respectively. Finally, repair was reduced by 30% to 50% in each of the ten nuclear regions in aging adults. However, this decrease in repair could not be explained by a reduction in expression of nucleotide excision repair genes, and we present a plausible mechanism, based on gene expression data, to account for this decrease. Conclusion Repair of UVC-induced DNA damage in C. elegans is similar kinetically and genetically to repair in humans. Furthermore, this important repair process slows significantly in aging C. elegans, the first whole organism in which this question has been addressed.

Meyer, Joel N; Boyd, Windy A; Azzam, Gregory A; Haugen, Astrid C; Freedman, Jonathan H; Van Houten, Bennett

2007-01-01

245

A gene expression fingerprint of C. elegans embryonic motor neurons  

PubMed Central

Background Differential gene expression specifies the highly diverse cell types that constitute the nervous system. With its sequenced genome and simple, well-defined neuroanatomy, the nematode C. elegans is a useful model system in which to correlate gene expression with neuron identity. The UNC-4 transcription factor is expressed in thirteen embryonic motor neurons where it specifies axonal morphology and synaptic function. These cells can be marked with an unc-4::GFP reporter transgene. Here we describe a powerful strategy, Micro-Array Profiling of C. elegans cells (MAPCeL), and confirm that this approach provides a comprehensive gene expression profile of unc-4::GFP motor neurons in vivo. Results Fluorescence Activated Cell Sorting (FACS) was used to isolate unc-4::GFP neurons from primary cultures of C. elegans embryonic cells. Microarray experiments detected 6,217 unique transcripts of which ~1,000 are enriched in unc-4::GFP neurons relative to the average nematode embryonic cell. The reliability of these data was validated by the detection of known cell-specific transcripts and by expression in UNC-4 motor neurons of GFP reporters derived from the enriched data set. In addition to genes involved in neurotransmitter packaging and release, the microarray data include transcripts for receptors to a remarkably wide variety of signaling molecules. The added presence of a robust array of G-protein pathway components is indicative of complex and highly integrated mechanisms for modulating motor neuron activity. Over half of the enriched genes (537) have human homologs, a finding that could reflect substantial overlap with the gene expression repertoire of mammalian motor neurons. Conclusion We have described a microarray-based method, MAPCeL, for profiling gene expression in specific C. elegans motor neurons and provide evidence that this approach can reveal candidate genes for key roles in the differentiation and function of these cells. These methods can now be applied to generate a gene expression map of the C. elegans nervous system.

Fox, Rebecca M; Von Stetina, Stephen E; Barlow, Susan J; Shaffer, Christian; Olszewski, Kellen L; Moore, Jason H; Dupuy, Denis; Vidal, Marc; Miller, David M

2005-01-01

246

A model of chemotaxis and associative learning in C. elegans.  

PubMed

The nematode C. elegans has attracted a great deal of interest from the neuroscience community due to the simplicity of its nervous system, which in the hermaphrodite is composed of just 302 neurons. C. elegans is known to engage in a number of sophisticated behaviours such as chemo- and thermotaxis. Experimental work has shown that these behaviours can be modified by experience and that C. elegans is capable of associative learning. In this paper, we focus on the chemotactic response of C. elegans to sodium chloride mediated by the ASE sensory neurons. We construct a biophysical model of the ASEL and ASER neurons that captures the time course of the ASE responses in response to up- and down-steps in NaCl concentration. We use this model to show that the time course of the ASE responses provide sufficient temporal resolution to successfully drive chemotaxis in C. elegans via steering, pirouettes and control of final turn angle. We show that these different locomotion strategies are individually capable of driving chemotaxis and that by working together they produce the best chemotactic response. We find that there is a separation into upward and downward drives mediated by the left and right ASE neurons. We show that the connectivity from ASEL and ASER must be of opposite polarity and that ASER, and the concomitant ability to sense when the worm is moving down the gradient, is more important for chemotaxis than ASEL, findings that are consistent with existing modelling studies in the literature. Finally, we examine associative learning in the network and show that experimental data can be explained by changes that occur at either the synaptic or sensory neuron level, the choice of which has distinct consequences for network function. PMID:22824944

Appleby, Peter A

2012-07-24

247

Voltage versus VAr\\/power-factor regulation on synchronous generators  

Microsoft Academic Search

When paralleled to the utility bus, synchronous generators can be controlled using either terminal voltage or VAr\\/power factor (PF) control. Selection is dependent upon the size of the generator and the stiffness of the connecting utility bus. For large generators where the kVA is significant, these machines are usually terminal voltage regulated and dictate the system's bus voltage. When smaller

Thomas W. Eberly; Richard C. Schaefer

2002-01-01

248

AN INVESTIGATION OF FLICKER REDUCTION USING AN ADAPTIVE VAR COMPENSATOR  

Microsoft Academic Search

A detailed computer model of a three-phase power network which includes inductive loads, resistance welders and an Adaptive Var Compensator (AVC) has been developed. The system configuration and parameters correspond to an irrdustrial customer served by a large electric utility. Welder operation produces severe cyclic flicker which leads to customer complaints. Computer studies have been conducted to determine the effectiveness

Juri V. Jatskevich; Oleg Wasynczuk

1997-01-01

249

Firm growth and productivity growth: evidence from a panel VAR  

Microsoft Academic Search

This article offers new insights into the processes of firm growth by applying a reduced-form Vector Autoregression (VAR) model to longitudinal panel data on French manufacturing firms. We observe the co-evolution of key variables such as growth of employment, sales and gross operating surplus, as well as growth of multifactor productivity. It seems that employment growth is negatively associated with

Alex Coad; Tom Broekel

2011-01-01

250

Ochratoxin A production by strains of Aspergillus niger var. niger.  

PubMed Central

In a survey of the occurrence of ochratoxin A (OA)-positive strains isolated from feedstuffs, two of the 19 isolates of Aspergillus niger var. niger that were studied produced OA in 2% yeast extract-15% sucrose broth and in corn cultures. This is the first report of production of OA by this species.

Abarca, M L; Bragulat, M R; Castella, G; Cabanes, F J

1994-01-01

251

Modelling and Simulation of Static Var Compensator with Matlab  

Microsoft Academic Search

This paper presents the modelling and simulation of Static Var Compensator (SVC) in power system studies by MATLAB. SVC is a shunt device of the Flexible AC Transmission Systems (FACTS) family using power electronics to control power flow and improve transient stability on power grids. In the first step, we have modelled mathematically with MathCAD how to analyze the rating

F. Z. Gherbi; S. Hadjeri; F. Ghezal

252

Inference on Impulse Response Functions in Structural VAR Models  

Microsoft Academic Search

Skepticism toward traditional identifying assumptions based on exclusion restrictions has led to a surge in the use of structural VAR models in which structural shocks are identified by restricting the sign of the responses of selected macroeconomic aggregates to these shocks. Researchers commonly report the vector of pointwise posterior medians of the impulse responses as a measure of central tendency

Atsushi Inoue; Lutz Kilian

2011-01-01

253

Static VAR compensation in a Southern African grid  

Microsoft Academic Search

The interconnection of neighboring utilities in the Southern African grid is becoming more strategic, but will be faced with the problems of system stability associated with remote generation and weak interconnections. A case study is presented where an SVC (static VAr compensator) was installed to optimize the interconnection between ESKOM and SWAWEK, the Namibian electricity supply utility. The SVC fulfills

S. Boshoff; P. V. Goosen; D. A. Marshall; U. Kleyenstuber

1992-01-01

254

VAR Model Analysis on Japan's OFDI and Industrial Structural Upgrading  

Microsoft Academic Search

This paper employs the VAR model to analyzes Japan's outward foreign direct investment and its domestic industrial structural upgrading. The Granger causality test results indicate that Japan's outward FDI does help explain the changes of the proportion of Japan's second industry and the tertiary industry, but couldn't help explain the changes of the proportion of the first industry. The co

Ren Liang

2011-01-01

255

New Static Var Control Using Force-Commutated Inverters  

Microsoft Academic Search

This paper describes the system outline and the operating results of a new type of 20MVA Static VAR Generator (SVG), which is already in operation in electric power field since January of 1980. This SVG consists of force-commutated inverters of the voltage source and can be operated in both, inductive and capacitive modes, by simple control of the output voltage

Yoshihiko Sumi; Yoshinobu Harumoto; Taizo Hasegawa; Masao Yano; Kazuo Ikeda; Toshiaki Matsuura

1981-01-01

256

Comparison of multilevel inverters for static VAr compensation  

Microsoft Academic Search

Inverter-based static VAr compensators (SVCs) can benefit from the use of a multilevel invertor structure which allows the elimination of the step-up transformer. The inherent high quality of the multistep waveform allows operation without PWM, thus high switching losses are avoided. This paper discusses the issues affecting the application of multilevel invertor structures as reactive power compensators and compares the

CLARK HOCHGRAF; ROBERT LASSETER; DEEPAK DIVAN; T.A. Lipo

1994-01-01

257

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

258

Application of static VAr compensators to increase power system damping  

Microsoft Academic Search

A theory for analyzing power system damping enhancement by application of static VAr compensators (SVCs) has been developed using the equal area criterion. Some fundamental issues, such as the effect of SVCs on a power system, how to control an SVC to improve system damping, and the differences between continuous and discontinuous control of SVC reactive power to achieve the

E.-Z. Zhou

1993-01-01

259

Analysis of Power System Stability Enhancement by Static VAR Compensators  

Microsoft Academic Search

The paper presents a fundamental analysis of the application of static VAr compensators (SVC) for stabilizing power systems. Basic SVC control strategies are examined in terms of enhancing the dynamic and transient stabilities, improving tieline transmission capacity and damping power oscillations. Synchronizing and damping torque contributions of the SVC are determined for different controls. The analysis is supplemented by digital

A. E. Hammad

1986-01-01

260

Damping torque analysis of static VAR system controllers  

Microsoft Academic Search

The use of a damping torque technique to examine the efficacy of various control signals, for reactive power modulation of a midpoint-located static VAr system (SVS) in enhancing the power transfer capability of long transmission lines is considered. A new auxiliary signal, the computed internal frequency (CIF), is proposed which synthesizes the internal voltage frequency of the remote generator from

K. R. Padiyar; R. K. Varma

1991-01-01

261

The causes of Spanish unemployment: A structural VAR approach  

Microsoft Academic Search

In this paper, we review the main causes of Spanish unemployment and weight them by estimating a simple macroeconomic model using the structural VAR methodology. By using this methodology we associate different causes of unemployment with shocks of different nature which have long-lasting effects due to full hysteresis. We claim that such an extreme assumption on ‘state dependency’ is reasonable,

Juan José Dolado; Juan F. Jimeno

1997-01-01

262

Do measures of monetary policy in a VAR make sense?  

Microsoft Academic Search

No. In many VARs, monetary policy shocks are identified with the least squares residuals from a regression of the federal funds rate on an assortment of variables. Such regressions appear to be structurally fragile and are at odds with other evidence on the nature of the Fed's reaction function; furthermore, the residuals from these regressions have little correlation with funds

Glenn D. Rudebusch

1996-01-01

263

Opening the Black Box: Structural Factor Models versus Structural VARs  

Microsoft Academic Search

In this Paper we study identification in dynamic factor models and argue that factor models are better suited than VARs to provide a structural representation of the macroeconomy. Factor models distinguish measurement errors and other idiosyncratic disturbances from structural macroeconomic shocks. As a consequence, the number of structural shocks is no longer equal to the number of variables included in

Mario Forni; Marco Lippi; Lucrezia Reichlin

2003-01-01

264

Effects of sterols on the development and aging of Caenorhabditis elegans.  

PubMed

Although Caenorhabditis elegans lacks several components of the de novo sterol biosynthetic pathway, it requires sterols as essential nutrients. Supplemental cholesterol undergoes extensive enzymatic modification in C. elegans to form certain sterols of unknown function. Since sterol metabolism in C. elegans differs from that in other species, such as mammals and yeast, it is important to examine how sterols regulate worm physiology. To examine the functions of sterols in C. elegans, a sterol-feeding experiment was carried out and several critical parameters, such as brood size, growth rate, and life span, were measured. In addition, the change in lipid distribution in C. elegans can be both qualitatively and quantitatively determined by various methods, including staining and chromatographic techniques. Taken together, the effects of sterols on C. elegans are very prominent and can be easily assessed using the techniques described here. PMID:19160668

Lee, Eun-Young; Jeong, Pan-Young; Kim, Sun-Young; Shim, Yhong-Hee; Chitwood, David J; Paik, Young-Ki

2009-01-01

265

A Monoclonal Antibody Toolkit for C. elegans  

PubMed Central

Background Antibodies are critical tools in many avenues of biological research. Though antibodies can be produced in the research laboratory setting, most research labs working with vertebrates avail themselves of the wide array of commercially available reagents. By contrast, few such reagents are available for work with model organisms. Methodology/Principal Findings We report the production of monoclonal antibodies directed against a wide range of proteins that label specific subcellular and cellular components, and macromolecular complexes. Antibodies were made to synaptobrevin (SNB-1), a component of synaptic vesicles; to Rim (UNC-10), a protein localized to synaptic active zones; to transforming acidic coiled-coil protein (TAC-1), a component of centrosomes; to CENP-C (HCP-4), which in worms labels the entire length of their holocentric chromosomes; to ORC2 (ORC-2), a subunit of the DNA origin replication complex; to the nucleolar phosphoprotein NOPP140 (DAO-5); to the nuclear envelope protein lamin (LMN-1); to EHD1 (RME-1) a marker for recycling endosomes; to caveolin (CAV-1), a marker for caveolae; to the cytochrome P450 (CYP-33E1), a resident of the endoplasmic reticulum; to ?-1,3-glucuronyltransferase (SQV-8) that labels the Golgi; to a chaperonin (HSP-60) targeted to mitochondria; to LAMP (LMP-1), a resident protein of lysosomes; to the alpha subunit of the 20S subcomplex (PAS-7) of the 26S proteasome; to dynamin (DYN-1) and to the ?-subunit of the adaptor complex 2 (APA-2) as markers for sites of clathrin-mediated endocytosis; to the MAGUK, protein disks large (DLG-1) and cadherin (HMR-1), both of which label adherens junctions; to a cytoskeletal linker of the ezrin-radixin-moesin family (ERM-1), which localized to apical membranes; to an ERBIN family protein (LET-413) which localizes to the basolateral membrane of epithelial cells and to an adhesion molecule (SAX-7) which localizes to the plasma membrane at cell-cell contacts. In addition to working in whole mount immunocytochemistry, most of these antibodies work on western blots and thus should be of use for biochemical fractionation studies. Conclusions/Significance We have produced a set of monoclonal antibodies to subcellular components of the nematode C. elegans for the research community. These reagents are being made available through the Developmental Studies Hybridoma Bank (DSHB).

Hadwiger, Gayla; Dour, Scott; Arur, Swathi; Fox, Paul; Nonet, Michael L.

2010-01-01

266

C.V. Riley’s lost aphids: Siphonophora fragariae var. immaculata and Aphis rapae var. laevigata (Hemiptera: Aphididae)  

Technology Transfer Automated Retrieval System (TEKTRAN)

The syntypes of Siphonophora fragariae var. immaculata Riley were rediscovered in the Aphidoidea collection of the United States of America National Museum of Natural History. Previously, S. fragariae immaculata was largely lost and forgotten. Through examination of the specimens, we hereby establ...

267

Overexpression of SUMO perturbs the growth and development of Caenorhabditis elegans  

Microsoft Academic Search

Small ubiquitin-related modifiers (SUMOs) are important regulator proteins. Caenorhabditis elegans contains a single SUMO ortholog, SMO-1, necessary for the reproduction of C. elegans. In this study, we constructed transgenic C. elegans strains expressing human SUMO-1 under the control of pan-neuronal (aex-3) or pan-muscular (myo-4) promoter and SUMO-2 under the control of myo-4 promoter. Interestingly, muscular overexpression of SUMO-1 or -2

Miia M. Rytinki; Merja Lakso; Petri Pehkonen; Vuokko Aarnio; Kaja Reisner; Mikael Peräkylä; Garry Wong; Jorma J. Palvimo

268

Characterization of the Caenorhabditis elegans G protein-coupled serotonin receptors  

Microsoft Academic Search

Serotonin (5-HT) regulates a wide range of behaviors in Caenorhabditis elegans, including egg laying, male mating, locomotion and pharyngeal pumping. So far, four serotonin receptors have been described in the nematode C. elegans, three of which are G protein-coupled receptors (GPCR), (SER-1, SER-4 and SER-7), and one is an ion channel (MOD-1). By searching the C. elegans genome for additional

Maïté Carre-Pierrat; David Baillie; Robert Johnsen; Rhonda Hyde; Anne Hart; Laure Granger; Laurent Ségalat

2006-01-01

269

Assessing the toxicity of contaminated soils using the nematode Caenorhabditis elegans as test organism  

Microsoft Academic Search

In this study, nine uncontaminated reference soils and 22 contaminated soils with different physico-chemical properties and contamination patterns were tested with a standardized toxicity test, using the nematode, Caenorhabditis elegans, as test organism. Fertility, growth and reproduction of C. elegans in the soils were compared with the exposure in standard soil Lufa St.2.2. C. elegans showed 100% fertility and a

S. Höss; S. Jänsch; T. Moser; T. Junker; J. Römbke

2009-01-01

270

AMulti-Generation Sublethal Assay of Phenols Using the Nematode Caenorhabditis elegans  

Microsoft Academic Search

The nematode Caenorhabditis elegans (C. elegans) was used for a multiple-generation toxicity bioassay of phenols. We examined the sublethal toxicity (fecundity and reproduction) of bisphenol A (BisA), 4-(1-adamantyl) phenol (Adp), and 4,4'-(1,3-adamantanediyl) diphenol (AdDP) over five generations using a Nematode Growth Medium (NGM) 1.7% agar plate. In the fourth generation, the phenols affected the fecundity rate of C. elegans at

Nobuaki Tominaga; Ashinya Kohra; T Aisen Iguchi; Dand Koji Arizono

271

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

272

Patterning of Caenorhabditis elegans Posterior Structures by the Abdominal-B Homolog, egl-5  

Microsoft Academic Search

The Caenorhabditis elegans body axis, like that of other animals, is patterned by the action of Hox genes. In order to examine the function of one C. elegans Hox gene in depth, we determined the postembryonic expression pattern of egl-5, the C. elegans member of the Abdominal-B Hox gene paralog group, by means of whole-mount staining with a polyclonal antibody.

Henrique B. Ferreira; Yinhua Zhang; Connie Zhao; Scott W. Emmons

1999-01-01

273

Unidirectional, electrotactic-response valve for Caenorhabditis elegans in microfluidic devices  

NASA Astrophysics Data System (ADS)

We report a nematode electrotactic-response valve (NERV) to control the locomotion of Caenorhabditis elegans (C. elegans) in microfluidic devices. This nonmechanical, unidirectional valve is based on creating a confined region of lateral electric field that is switchable and reversible. We observed that C. elegans do not prefer to pass through this region if the field lines are incident to its forward movement. Upon reaching the boundary of the NERV, the incident worms partially penetrate the field region, pull back, and turn around. The NERV is tested on three C. elegans mutants: wild-type (N2), lev-8, and acr-16.

Carr, John A.; Lycke, Roy; Parashar, Archana; Pandey, Santosh

2011-04-01

274

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

275

Effects of Chelators on Species and Bioavailability of Cadmium in Soil to Daucus carota var. sativa and Brassica juncea var. multiceps  

Microsoft Academic Search

A pot incubation study was conducted to investigate the feasibility of using Daucus carota var. sativa (carrot) and Brassica juncea var. multiceps (potherb mustard) for phytoremediation of Cd-contaminated soils and evaluateing the effects of chelating agents (EDTA, EGTA, DTPA and citric acid) application on metal uptake by both plants. It was shown that, the content of water soluble and exchangeable

Zheng Ming-xia; Li Lai-qing; Feng Liu; Liu Jie; Chen Ming

2009-01-01

276

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.

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

2012-01-01

277

Systematic Analysis of Pleiotropy in C. elegans Early Embryogenesis  

PubMed Central

Pleiotropy refers to the phenomenon in which a single gene controls several distinct, and seemingly unrelated, phenotypic effects. We use C. elegans early embryogenesis as a model to conduct systematic studies of pleiotropy. We analyze high-throughput RNA interference (RNAi) data from C. elegans and identify “phenotypic signatures”, which are sets of cellular defects indicative of certain biological functions. By matching phenotypic profiles to our identified signatures, we assign genes with complex phenotypic profiles to multiple functional classes. Overall, we observe that pleiotropy occurs extensively among genes involved in early embryogenesis, and a small proportion of these genes are highly pleiotropic. We hypothesize that genes involved in early embryogenesis are organized into partially overlapping functional modules, and that pleiotropic genes represent “connectors” between these modules. In support of this hypothesis, we find that highly pleiotropic genes tend to reside in central positions in protein-protein interaction networks, suggesting that pleiotropic genes act as connecting points between different protein complexes or pathways.

Zou, Lihua; Sriswasdi, Sira; Ross, Brian; Missiuro, Patrycja V.; Liu, Jun; Ge, Hui

2008-01-01

278

Functional characterization of Caenorhabditis elegans DNA topoisomerase III?  

PubMed Central

To investigate the function of a DNA topoisomerase III enzyme in Caenorhabditis elegans, the full-length cDNA of C.elegans DNA topoisomerase III? was cloned. The deduced amino acid sequence exhibited identities of 48 and 39% with those of human DNA topoisomerase III? and Saccharomyces cerevisiae DNA topoisomerase III, respectively. The overexpressed polypeptide showed an optimal activity for removing negative DNA supercoils at a relatively high temperature of 52–57°C, which is similar to the optimum temperatures of other eukaryotic DNA topoisomerase III enzymes. When topoisomerase III? expression was interfered with by a cognate double-stranded RNA injection, pleiotropic phenotypes with abnormalities in germ cell proliferation, oogenesis and embryogenesis appeared. These phenotypes were well correlated with mRNA expression localized in the meiotic cells of gonad and early embryonic cells.

Kim, You-Chan; Lee, Junho; Koo, Hyeon-Sook

2000-01-01

279

Developmental decisions: balancing genetics and the environment by C. elegans.  

PubMed

The small nematode C. elegans is characterized by developing through a highly coordinated, reproducible cell lineage that serves as the basis of many studies focusing on the development of multi-lineage organisms. Indeed, the reproducible cell lineage enables discovery of developmental defects that occur in even a single cell. Only recently has attention been focused on how these animals modify their genetically programmed cell lineages to adapt to altered environments. Here, we summarize the current understanding of how C. elegans responds to food deprivation by adapting their developmental program in order to conserve energy. In particular, we highlight the AMPK-mediated and insulin-like growth factor signaling pathways that are the principal regulators of induced cell cycle quiescence. PMID:22510569

Tobin, David V; Saito, Richard Mako

2012-05-01

280

Fat synthesis and adiposity regulation in Caenorhabditis elegans.  

PubMed

Understanding the regulation of fat synthesis and the consequences of its misregulation is of profound significance for managing the obesity epidemic and developing obesity therapeutics. Recent work in the roundworm Caenorhabditis elegans has revealed the importance of evolutionarily conserved pathways of fat synthesis and nutrient sensing in adiposity regulation. The powerful combination of mutational and reverse genetic analysis, genomics, lipid analysis, and cell-specific expression studies enables dissection of complicated pathways at the level of a whole organism. This review summarizes recent studies in C. elegans that offer insights into the regulation of adiposity by conserved transcription factors, insulin and growth factor signaling, and unsaturated fatty acid synthesis. Increased understanding of fat-storage pathways might lead to future obesity therapies. PMID:19181539

Watts, Jennifer L

2009-01-31

281

Mechanical Cues in the Early Embryogenesis of Caenorhabditis elegans  

PubMed Central

Biochemical signaling pathways in developmental processes have been extensively studied, yet the role of mechanical cues during embryogenesis is much less explored. Here we have used selective plane illumination microscopy in combination with a simple mechanical model to quantify and rationalize cell motion during early embryogenesis of the small nematode Caenorhabditis elegans. As a result, we find that cell organization in the embryo until gastrulation is well described by a purely mechanical model that predicts cells to assume positions in which they face the least repulsive interactions from other cells and the embryo’s egg shell. Our findings therefore suggest that mechanical interactions are key for a rapid and robust cellular arrangement during early embryogenesis of C. elegans.

Fickentscher, Rolf; Struntz, Philipp; Weiss, Matthias

2013-01-01

282

Dynamics of C. elegans in various fluidic environments  

NASA Astrophysics Data System (ADS)

C. elegans is a freely moving soil nematode that crawls or swims by propagating a body wave backwards. In fluids we investigate its swimming locomotion as the fluid viscosity is varied over many orders of magnitude and in the presence of non-Newtonian fluid responses. For Newtonian fluids we find power-law relations between swimming speed and fluid viscosity, and these relations are not in accordance with assumptions of constant power input to the fluid. We also find that the Strouhal frequency is nearly independent of viscosity and swimming speed. We investigate the influence of confinement on C. elegans locomotion and find that interactions between confining walls and body undulations can markedly increase swimming speed.

Jung, Sunghwan; Kim, Erica; Piano, Fabio; Zhang, Jun; Shelley, Michael

2006-11-01

283

Organization of neuronal microtubules in the nematode Caenorhabditis elegans.  

PubMed

We have studied the organization of microtubules in neurons of the nematode Caenorhabditis elegans. Six neurons, which we call the microtubule cells, contain bundles of darkly staining microtubules which can be followed easily in serial-section electron micrographs. Reconstruction of individual microtubules in these cells indicate that most, if not all, microtubules are short compared with the length of the cell process. Average microtubule length varies characteristically with cell type. The arrangement of microtubules gives an overall polarity to each bundle: the distal ends of the microtubles are on the outside of the bundle, whereas the proximal ends are preferentially inside. The distal and proximal ends each have a characteristic appearance indicating that these microtubules may have a polarity of their own. Short microtubules in processes of other neurons in C. elegans have also been observed. PMID:479300

Chalfie, M; Thomson, J N

1979-07-01

284

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.

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

2010-01-01

285

Sensory regulation of C. elegans male mate-searching behaviour  

PubMed Central

Summary How do animals integrate internal drives and external environmental cues to coordinate behaviours? We address this question studying mate-searching behaviour in C. elegans. C. elgans males explore their environment in search of mates (hermaphrodites) and will leave food if mating partners are absent. However, when mates and food coincide, male exploratory behaviour is suppressed and males are retained on the food source. We show that the drive to explore is stimulated by male specific neurons in the tail, the ray neurons. Periodic contact with the hermaphrodite detected through ray neurons changes the male’s behaviour during periods of no contact and prevents the male from leaving the food source. The hermaphrodite signal is conveyed by male-specific interneurons that are post-synaptic to the rays and that send processes to the major integrative center in the head. This study identifies key parts of the neural circuit that regulates a sexual appetitive behaviour in C. elegans.

Barrios, Arantza; Nurrish, Stephen; Emmons, Scott W.

2009-01-01

286

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

287

From Fertilization to Egg Laying in C. elegans  

NSDL National Science Digital Library

Video of the fertilization of the C. elegans oocyte, the fusion of the egg and sperm nuclei, and the egg laying. This video is featured on the HHMI DVD, The Meaning of Sex: Genes and Gender, available free from HHMI. Also, this video is one minute 12 seconds in length, and available in Quicktime (6 MB) and Windows Media (8 MB). All sex determination videos are located at: http://www.hhmi.org/biointeractive/gender/video.html.

Howard Hughes Medical Institute (HHMI;)

2008-06-06

288

Antifungal Chemical Compounds Identified Using a C. elegans Pathogenicity Assay  

PubMed Central

There is an urgent need for the development of new antifungal agents. A facile in vivo model that evaluates libraries of chemical compounds could solve some of the main obstacles in current antifungal discovery. We show that Candida albicans, as well as other Candida species, are ingested by Caenorhabditis elegans and establish a persistent lethal infection in the C. elegans intestinal track. Importantly, key components of Candida pathogenesis in mammals, such as filament formation, are also involved in nematode killing. We devised a Candida-mediated C. elegans assay that allows high-throughput in vivo screening of chemical libraries for antifungal activities, while synchronously screening against toxic compounds. The assay is performed in liquid media using standard 96-well plate technology and allows the study of C. albicans in non-planktonic form. A screen of 1,266 compounds with known pharmaceutical activities identified 15 (?1.2%) that prolonged survival of C. albicans-infected nematodes and inhibited in vivo filamentation of C. albicans. Two compounds identified in the screen, caffeic acid phenethyl ester, a major active component of honeybee propolis, and the fluoroquinolone agent enoxacin exhibited antifungal activity in a murine model of candidiasis. The whole-animal C. elegans assay may help to study the molecular basis of C. albicans pathogenesis and identify antifungal compounds that most likely would not be identified by in vitro screens that target fungal growth. Compounds identified in the screen that affect the virulence of Candida in vivo can potentially be used as “probe compounds” and may have antifungal activity against other fungi.

Breger, Julia; Fuchs, Beth Burgwyn; Aperis, George; Moy, Terence I; Ausubel, Frederick M; Mylonakis, Eleftherios

2007-01-01

289

Effects of seven organic pollutants on soil nematode Caenorhabditis elegans  

Microsoft Academic Search

Caenorhabditis elegans is a free-living soil nematode that is commonly used as a model for toxicity tests. The aim of this study was to investigate the toxicity of seven organic pollutants: four azaarenes (quinoline, acridine, phenazine, and 1,10-phenanthroline), short-chain chlorinated paraffins, and two organochlorinated pesticides (toxaphene and hexachlorobenzene). The exposure to all chemicals was carried out in three test media

Ivana Sochová; Jakub Hofman; Ivan Holoubek

2007-01-01

290

Calcium signaling surrounding fertilization in the nematode Caenorhabditis elegans.  

PubMed

Calcium plays a prominent role during fertilization in many animals. This review focuses on roles of Ca(2+) during the events around fertilization in the model organism, Caenorhabditis elegans. Specifically, the role of Ca(2+) in sperm, oocytes and the surrounding somatic tissues during fertilization will be discussed, with the focus on sperm activation, meiotic maturation of oocytes, ovulation, sperm-egg interaction and fertilization. PMID:23218668

Singaravelu, Gunasekaran; Singson, Andrew

2012-12-04

291

A Genetic Dissociation of Learning and Recall in Caenorhabditis elegans  

Microsoft Academic Search

A learning event can be dissociated into 3 components: acquisition, storage, and recall. When the laboratory wild-type strain of Caenorhabditis elegans (N2 strain) is exposed to benzaldehyde in the absence of food, the worms display a reduction of their attractive response to this volatile odorant. This results from the association between benzaldehyde and a nutrient-deficient environment. Another wild-type isolate, the

Karen Atkinson-Leadbeater; William M. Nuttley; Derek van der Kooy

2004-01-01

292

Mutations affecting sensitivity to ethanol in the nematode, Caenorhabditis elegans.  

PubMed

Mutations in nine genes have been identified in the nematode, Caenorhabditis elegans, which control sensitivity to ethanol. The interaction of these genes has been examined and used to determine a genetic pathway controlling sensitivity to ethanol. The nature of this pathway indicates that ethanol exerts its anesthetic actions at more than one site of action. These results also indicate that ethanol is similar in its effects to the volatile anesthetics, enflurane and isoflurane. PMID:8749805

Morgan, P G; Sedensky, M M

1995-12-01

293

Model organismsChemistry-to-gene screens in Caenorhabditis elegans  

Microsoft Academic Search

The nematode worm Caenorhabditis elegans is a genetic model organism linked to an impressive portfolio of fundamental discoveries in biology. This free-living nematode, which can be easily and inexpensively grown in the laboratory, is also a natural vehicle for screening for drugs that are active against nematode parasites. Here, we show that chemistry-to-gene screens using this animal model can define

Andrew K. Jones; Steven D. Buckingham; David B. Sattelle

2005-01-01

294

Ethanol interferes with gustatory plasticity in Caenorhabditis elegans  

Microsoft Academic Search

Ethanol affects the formation of learning and memory in many species. However, the molecular mechanisms underlying the behavioral effects of ethanol are still poorly understood. In Caenorhabditis elegans, gustatory plasticity is a simple learning paradigm, in which animals after prolonged pre-exposure to a chemo-attractive salt in the absence of food show chemo-aversion to this salt during subsequent chemotaxis test stage.

Ying Wang; Lichun Tang; Xiaojun Feng; Wei Du; Bi-Feng Liu

2011-01-01

295

Antifungal chemical compounds identified using a C. elegans pathogenicity assay.  

PubMed

There is an urgent need for the development of new antifungal agents. A facile in vivo model that evaluates libraries of chemical compounds could solve some of the main obstacles in current antifungal discovery. We show that Candida albicans, as well as other Candida species, are ingested by Caenorhabditis elegans and establish a persistent lethal infection in the C. elegans intestinal track. Importantly, key components of Candida pathogenesis in mammals, such as filament formation, are also involved in nematode killing. We devised a Candida-mediated C. elegans assay that allows high-throughput in vivo screening of chemical libraries for antifungal activities, while synchronously screening against toxic compounds. The assay is performed in liquid media using standard 96-well plate technology and allows the study of C. albicans in non-planktonic form. A screen of 1,266 compounds with known pharmaceutical activities identified 15 (approximately 1.2%) that prolonged survival of C. albicans-infected nematodes and inhibited in vivo filamentation of C. albicans. Two compounds identified in the screen, caffeic acid phenethyl ester, a major active component of honeybee propolis, and the fluoroquinolone agent enoxacin exhibited antifungal activity in a murine model of candidiasis. The whole-animal C. elegans assay may help to study the molecular basis of C. albicans pathogenesis and identify antifungal compounds that most likely would not be identified by in vitro screens that target fungal growth. Compounds identified in the screen that affect the virulence of Candida in vivo can potentially be used as "probe compounds" and may have antifungal activity against other fungi. PMID:17274686

Breger, Julia; Fuchs, Beth Burgwyn; Aperis, George; Moy, Terence I; Ausubel, Frederick M; Mylonakis, Eleftherios

2007-02-01

296

Stop making nonSense: the C. elegans smg genes  

Microsoft Academic Search

Cells monitor the quality of their mRNAs and degrade any transcripts that are poorly or incompletely translated. In the nematode Caenorhabditis elegans, degradation by the mRNA surveillance pathway depends on seven smg genes. Three of these genes also have a role in a second mRNA degradation pathway called RNA interference (RNAi), which is triggered by double-stranded RNA (dsRNA). Here I

Susan E. Mango

2001-01-01

297

Carbonylated proteins are eliminated during reproduction in C. elegans.  

PubMed

Oxidatively damaged proteins accumulate with age in many species (Stadtman (1992) Science257, 1220-1224). This means that damage must be reset at the time of reproduction. To visualize this resetting in the roundworm Caenorhabditis elegans, a novel immunofluorescence technique that allows the detection of carbonylated proteins in situ was developed. The application of this technique revealed that carbonylated proteins are eliminated during C. elegans reproduction. This purging occurs abruptly within the germline at the time of oocyte maturation. Surprisingly, the germline was markedly more oxidized than the surrounding somatic tissues. Because distinct mechanisms have been proposed to explain damage elimination in yeast and mice (Aguilaniu et al. (2003) Science299, 1751-1753; Hernebring et al. (2006) Proc Natl Acad Sci USA103, 7700-7705), possible common mechanisms between worms and one of these systems were tested. The results show that, unlike in yeast (Aguilaniu et al. (2003) Science299, 1751-1753; Erjavec et al. (2008) Proc Natl Acad Sci USA105, 18764-18769), the elimination of carbonylated proteins in worms does not require the presence of the longevity-ensuring gene, SIR-2.1. However, similar to findings in mice (Hernebring et al. (2006) Proc Natl Acad Sci USA103, 7700-7705), proteasome activity in the germline is required for the resetting of carbonylated proteins during reproduction in C. elegans. Thus, oxidatively damaged proteins are eliminated during reproduction in worms through the proteasome. This finding suggests that the resetting of damaged proteins during reproduction is conserved, therefore validating the use of C. elegans as a model to study the molecular basis of damage elimination. PMID:21040398

Goudeau, Jérôme; Aguilaniu, Hugo

2010-10-29

298

Chaperone-interacting TPR proteins in Caenorhabditis elegans.  

PubMed

The ATP-hydrolyzing molecular chaperones Hsc70/Hsp70 and Hsp90 bind a diverse set of tetratricopeptide repeat (TPR)-containing cofactors via their C-terminal peptide motifs IEEVD and MEEVD. These cochaperones contribute to substrate turnover and confer specific activities to the chaperones. Higher eukaryotic genomes encode a large number of TPR-domain-containing proteins. The human proteome contains more than 200 TPR proteins, and that of Caenorhabditis elegans, about 80. It is unknown how many of them interact with Hsc70 or Hsp90. We systematically screened the C. elegans proteome for TPR-domain-containing proteins that likely interact with Hsc70 and Hsp90 and ranked them due to their similarity with known chaperone-interacting TPRs. We find C. elegans to encode many TPR proteins, which are not present in yeast. All of these have homologs in fruit fly or humans. Highly ranking uncharacterized open reading frames C33H5.8, C34B2.5 and ZK370.8 may encode weakly conserved homologs of the human proteins RPAP3, TTC1 and TOM70. C34B2.5 and ZK370.8 bind both Hsc70 and Hsp90 with low micromolar affinities. Mutation of amino acids involved in EEVD binding disrupts the interaction. In vivo, ZK370.8 is localized to mitochondria in tissues with known chaperone requirements, while C34B2.5 colocalizes with Hsc70 in intestinal cells. The highest-ranking open reading frame with non-conserved EEVD-interacting residues, F52H3.5, did not show any binding to Hsc70 or Hsp90, suggesting that only about 15 of the TPR-domain-containing proteins in C. elegans interact with chaperones, while the many others may have evolved to bind other ligands. PMID:23727266

Haslbeck, Veronika; Eckl, Julia M; Kaiser, Christoph J O; Papsdorf, Katharina; Hessling, Martin; Richter, Klaus

2013-05-29

299

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.

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

2010-01-01

300

Surfactant stimulation of growth in the nematode Caenorhabditis elegans  

Microsoft Academic Search

Size fractionation has been used to isolate L1L2 larvae from mixed cultures of the nematode, Caenorhabditis elegans. Worm lengths have been compared during growth in synchronized liquid and agar cultures. Supplementation of liquid S medium with 10 ppm surfactant (Pluronics F-68, F-127, F-38, L-35; Tween-20 or Triton X-100) promoted a significant stimulation of growth over three days in all cases.

Mohammed H. A. Z. Mutwakil; Tamazin J. G. Steele; Kenneth C. Lowe; David I. de Pomerai

1997-01-01

301

The identification and suppression of inherited neurodegeneration in Caenorhabditis elegans  

Microsoft Academic Search

The dominant mutation deg-1(u38) results in a toxic gene product that leads to the late-onset degeneration of a small number of neurons in the nematode Caenorhabditis elegans. Both intragenic and extragenic mutations as well as changes in wild-type gene dosage can delay or block the time of onset of the neuronal deaths. The deg-1 gene has been cloned and a

Martin Chalfie; Eve Wolinsky

1990-01-01

302

Neurotoxic effects of TDP43 overexpression in C. elegans  

Microsoft Academic Search

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

P. E. A. Ash; Y.-J. Zhang; C. M. Roberts; T. Saldi; H. Hutter; E. Buratti; L. Petrucelli; C. D. Link

2010-01-01

303

A C. elegans model to study human metabolic regulation.  

PubMed

Lipid metabolic disorder is a critical risk factor for metabolic syndrome, triggering debilitating diseases like obesity and diabetes. Both obesity and diabetes are the epicenter of important medical issues, representing a major international public health threat. Accumulation of fat in adipose tissue, muscles and liver and/or the defects in their ability to metabolize fatty acids, results in insulin resistance. This triggers an early pathogenesis of type 2 diabetes (T2D). In mammals, lipid metabolism involves several organs, including the brain, adipose tissue, muscles, liver, and gut. These organs are part of complex homeostatic system and communicate through hormones, neurons and metabolites. Our study dissects the importance of mammalian Krüppel-like factors in over all energy homeostasis. Factors controlling energy metabolism are conserved between mammals and Caenorhabditis elegans providing a new and powerful strategy to delineate the molecular pathways that lead to metabolic disorder. The C. elegans intestine is our model system where genetics, molecular biology, and cell biology are used to identify and understand genes required in fat metabolism. Thus far, we have found an important role of C. elegans KLF in FA biosynthesis, mitochondrial proliferation, lipid secretion, and ?-oxidation. The mechanism by which KLF controls these events in lipid metabolism is unknown. We have recently observed that C. elegans KLF-3 selectively acts on insulin components to regulate insulin pathway activity. There are many factors that control energy homeostasis and defects in this control system are implicated in the pathogenesis of human obesity and diabetes. In this review we are discussing a role of KLF in human metabolic regulation. PMID:23557393

Hashmi, Sarwar; Wang, Yi; Parhar, Ranjit S; Collison, Kate S; Conca, Walter; Al-Mohanna, Futwan; Gaugler, Randy

2013-04-04

304

A novel non-coding DNA family in Caenorhabditis elegans  

Microsoft Academic Search

Many repetitive elements, for example, SINEs, LINEs, LTR-retrotransposons and other SSRs are dispersed throughout eukaryotic genomes. To understand the biological function of these repetitive elements is of great current research interest. In this study, we report on the identification of a novel non-coding DNA family, designated CE1 family, in the nematode C. elegans genome. Some CE1 elements constituted a large

Yasuo Takashima; Tetsuya Bando; Hiroaki Kagawa

2007-01-01

305

Purification and Characterization of Recombinant Caenorhabditis elegans Metallothionein  

Microsoft Academic Search

The roundworm Caenorhabditis elegans adapted for survival at high concentrations of Cd(II) expresses two isoforms of metallothionein, CeMT-I and CeMT-II. To characterize one of these proteins CeMT-II was prepared as its Cd containing form by expressing its cDNA heterologously in Escherichia coli. The purified 63-amino-acid protein was identified as the desired product by ion-spray mass spectrometry and was found to

Chunhui You; Elaine A Mackay; Peter M Gehrig; Peter E Hunziker; Jeremias H. R Kägi

1999-01-01

306

Improving the Caenorhabditis elegans genome annotation using machine learning.  

PubMed

For modern biology, precise genome annotations are of prime importance, as they allow the accurate definition of genic regions. We employ state-of-the-art machine learning methods to assay and improve the accuracy of the genome annotation of the nematode Caenorhabditis elegans. The proposed machine learning system is trained to recognize exons and introns on the unspliced mRNA, utilizing recent advances in support vector machines and label sequence learning. In 87% (coding and untranslated regions) and 95% (coding regions only) of all genes tested in several out-of-sample evaluations, our method correctly identified all exons and introns. Notably, only 37% and 50%, respectively, of the presently unconfirmed genes in the C. elegans genome annotation agree with our predictions, thus we hypothesize that a sizable fraction of those genes are not correctly annotated. A retrospective evaluation of the Wormbase WS120 annotation [] of C. elegans reveals that splice form predictions on unconfirmed genes in WS120 are inaccurate in about 18% of the considered cases, while our predictions deviate from the truth only in 10%-13%. We experimentally analyzed 20 controversial genes on which our system and the annotation disagree, confirming the superiority of our predictions. While our method correctly predicted 75% of those cases, the standard annotation was never completely correct. The accuracy of our system is further corroborated by a comparison with two other recently proposed systems that can be used for splice form prediction: SNAP and ExonHunter. We conclude that the genome annotation of C. elegans and other organisms can be greatly enhanced using modern machine learning technology. PMID:17319737

Rätsch, Gunnar; Sonnenburg, Sören; Srinivasan, Jagan; Witte, Hanh; Müller, Klaus-R; Sommer, Ralf-J; Schölkopf, Bernhard

2006-12-21

307

OSMOTIC AVOIDANCE DEFECTIVE MUTANTS OF THE NEMATODE CAENORHABDITIS ELEGANS  

Microsoft Academic Search

A wild-type strain of the nematode Caenorhabditis elegans has been shown to avoid high concentrations of a number of sugars and salts. Individual and population assays for this response were developed and mutants were selected for their inability to avoid high concentrations of fructose or NaC1. Seven nonavoiding mutants representing six complementation groups were isolated and characterized. Genetic studies indicate

JOSEPH G. CULOTTI; RICHARD L. RUSSELL

1978-01-01

308

Biotransformation of fluorene by the fungus Cunninghamella elegans  

SciTech Connect

Fluorene, a tricyclic aromatic hydrocarbon, is formed during the combustion of fossil fuels and is an important pollutant of aquatic ecosystems where it is highly toxic to fish and algae. Few studies on microbial biodegradation of fluorene have been reported. This investigation describes the metabolism of fluorene by the fungus Cunninghamella elegans ATCC 36112 and the identification of major metabolites. 26 refs., 2 figs., 1 tab.

Pothuluri, J.V.; Freeman, J.P.; Evans, F.E.; Cerniglia, C.E. (Food and Drug Administration, Jefferson, AR (United States))

1993-06-01

309

Genetic Regulation of Unsaturated Fatty Acid Composition in C. elegans  

Microsoft Academic Search

Delta-9 desaturases, also known as stearoyl-CoA desaturases, are lipogenic enzymes responsible for the generation of vital components of membranes and energy storage molecules. We have identified a novel nuclear hormone receptor, NHR-80, that regulates delta-9 desaturase gene expression in Caenorhabditis elegans. Here we describe fatty acid compositions, lifespans, and gene expression studies of strains carrying mutations in nhr-80 and in

Trisha J Brock; John Browse; Jennifer L Watts

2006-01-01

310

Application of Adaptive VAr Compensator for Transmission System Flicker Correction  

Microsoft Academic Search

This paper reviews the application of an adaptive var compensator to reduce voltage flicker associated with the stalling of large motors. The ease considered involves the sequential starting of two 1000 hp motors in an across-the-line mode. The motors are served by a 44 kV-4.16 kV dedicated substation. The 44 kV transmission line also serves over 2000 residential and commercial

E. S. Thomas

2006-01-01

311

Thermotolerant single cell protein production by Kluyveromyces marxianus var. marxianus  

Microsoft Academic Search

Summary Amino acid analyses were undertaken on single cell protein (SCP) produced by thermotolerant strains ofKluyveromyces marxianus var.marxianus grown on sugar cane molasses at 40°C. The maximum conversion of available sugars to biomass at 45°C was only 10.8% (g dry wt.·g-1 total sugars). The amino acid composition of the SCP did not differ markedly from that reported for other yeast

Paul J. Anderson; Keith E. McNeil; Kenneth Watson

1988-01-01

312

Triterpenoid biosynthesis in tissue cultures of Glycyrrhiza glabra var. glandulifera  

Microsoft Academic Search

The incorporation of [1-14C]acetate and [214 C]mevalonate into free and esterified triterpen-3-ols was examined in original plant organs and tissue cultures of Glycyrrhiza glabra var. glandulifera. Both substrates labeled ß-amyrin, an oleanane-type triterpene, and cycloartenol and 24-methylenecycloartanol, both of which are intermediates of phytosterol biosynthesis. The label in esterified triterpenes was distributed mainly in phytosterol intermediates, but not in ß-amyrin.

S. Ayabe; H. Takano; To Fujita; T. Furuya; H. Hirota; T. Takahashi

1990-01-01

313

Plant regeneration from callus culture of Cymbidium ensifolium var. misericors  

Microsoft Academic Search

Totipotent calli of Cymbidium ensifolium var. misericors, a locally grown orchid of high commercial value, were induced from sections of pseudobulbs, rhizomes and\\u000a roots of seed-derived plantlets on 1\\/2-strength Murashige and Skoog medium plus 10 mg\\/l 2,4-dichlorophenoxyacetic acid and\\u000a 0.1 mg\\/l thiadiazuron. The calli could be maintained by subculturing in the same medium. The calli could be induced to develop

C. Chang; W. C. Chang

1998-01-01

314

Effects of seven organic pollutants on soil nematode Caenorhabditis elegans.  

PubMed

Caenorhabditis elegans is a free-living soil nematode that is commonly used as a model for toxicity tests. The aim of this study was to investigate the toxicity of seven organic pollutants: four azaarenes (quinoline, acridine, phenazine, and 1,10-phenanthroline), short-chain chlorinated paraffins, and two organochlorinated pesticides (toxaphene and hexachlorobenzene). The exposure to all chemicals was carried out in three test media (soil, agar, and aquatic medium), and adult mortality was evaluated after 24 and 48 h. Toxaphene was the most toxic substance with LC(50) (48 h) of 379 mg/kg in the soil and 0.2 mg/L in the aquatic medium. Quinoline was the most toxic chemical in agar test with LC(50) (48 h) of 10 mg/L. HCB showed a very low toxicity in all tests, maybe due to its very low water solubility. Longer than 24-h test duration was found necessary for getting more correct data on toxicity. In comparison with other studies, C. elegans was less sensitive than other soil invertebrates. Different response might be attributed to different exposure routes and shorter test duration. Equilibrium partitioning theory was used to calculate K(oc) from results of soil and aquatic tests but this approach was found not working. Our results suggest that the tests with nematode C. elegans should be included to the battery of tests for risk assessment of POPs in soil. PMID:17449100

Sochová, Ivana; Hofman, Jakub; Holoubek, Ivan

2007-04-20

315

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.

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

2013-01-01

316

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.

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

2001-01-01

317

Fungal metabolism and detoxification of fluoranthene. [Cunninghamella elegans  

SciTech Connect

Five metabolites produced by Cunninghamella elegans from fluoranthene (FA) in biotransformation studies were investigated for mutagenic activity towards Salmonella typhimurium TA100 and TA104. Whereas FA displayed positive, dose-related mutagenic responses in both tester strains in the presence of a rat liver homogenate fraction, 3-FA-{beta}-glucopyranoside, 3-(8-hydroxy-FA)-{beta}-glucopyranoside, FA trans-2,3-dihydrodiol, and 8-hydroxy-FA trans-2,3-dihydrodiol were negative. 9-Hydroxy-FA trans-2,3-dihydrodiol showed a weak positive response in S. typhimurium TA100. Mutagenicity assays performed with samples extracted at 24-h intervals during incubation of C. elegans with FA for 120 h showed that mutagenic activity decreased with time. Comparative studies with rat liver microsomes indicated that FA trans-2,3-dihydrodiol, the previously identified proximal mutagenic metabolite of FA, was the major metabolite. The circular dichroism spectrum of the rat liver microsomal FA trans-2,3-dihydrodiol indicated that is was optically active. In contrast, the circular dichroism spectrum of the fungal FA trans-2,3-dihydrodiol showed no optical activity. These results indicate that C. elegans has the potential to detoxify FA and that the stereochemistry of its trans-2,3-dihydrodiol metabolite reduces its mutagenic potential.

Pothuluri, J.V.; Heflich, R.H.; Fu, P.P.; Cerniglia, C.E. (Food and Drug Administration, Jefferson, AR (United States))

1992-03-01

318

Dietary regulation of hypodermal polyploidization in C. elegans  

PubMed Central

Background Dietary restriction (DR) results in increased longevity, reduced fecundity and reduced growth in many organisms. Though many studies have examined the effects of DR on longevity and fecundity, few have investigated the effects on growth. Results Here we use Caenorhabditis elegans to determine the mechanisms that regulate growth under DR. We show that rather than a reduction in cell number, decreased growth in wild type C. elegans under DR is correlated with lower levels of hypodermal polyploidization. We also show that mutants lacking wild type sensory ciliated neurons are small, exhibit hypo-polyploidization and more importantly, when grown under DR, reduce their levels of endoreduplication to a lesser extent than wild type, suggesting that these neurons are required for the regulation of hypodermal polyploidization in response to DR. Similarly, we also show that the cGMP-dependent protein kinase EGL-4 and the SMA/MAB signalling pathway regulate polyploidization under DR. Conclusion We show C. elegans is capable of actively responding to food levels to regulate adult ploidy. We suggest this response is dependent on the SMA/MAB signalling pathway.

Tain, Luke S; Lozano, Encarnacion; Saez, Alberto G; Leroi, Armand M

2008-01-01

319

Two-color GFP expression system for C. elegans.  

PubMed

We describe the use of modified versions of the Aequora victoria green fluorescent protein (GFP) to simultaneously follow the expression and distribution of two different proteins in the nematode, Caenorhabditis elegans. A cyan-colored GFP derivative, designated CFP, contains amino acid (aa) substitutions Y66W, N146I, M153T and V163A relative to the original GFP sequence and is similar to the previously reported "W7" form. A yellow-shifted GFP derivative, designated YFP, contains aa substitutions S65G, V68A, S72A and T203Y and is similar to the previously described "I0C" variant. Coding regions for CFP and YFP were constructed in the context of a high-activity C. elegans expression system. Previously characterized promoters and localization signals have been used to express CFP and YFP in C. elegans. Filter sets designed to distinguish YFP and CFP fluorescence spectra allowed visualization of the two distinct forms of GFP in neurons and in muscle cells. A series of expression vectors carrying CFP and YFP have been constructed and are being made available to the scientific community. PMID:10337485

Miller, D M; Desai, N S; Hardin, D C; Piston, D W; Patterson, G H; Fleenor, J; Xu, S; Fire, A

1999-05-01

320

Undulatory Locomotion of Caenorhabditis elegans on Wet Surfaces  

PubMed Central

The physical and biomechanical principles that govern undulatory movement on wet surfaces have important applications in physiology, physics, and engineering. The nematode Caenorhabditis elegans, with its highly stereotypical and functionally distinct sinusoidal locomotory gaits, is an excellent system in which to dissect these properties. Measurements of the main forces governing the C. elegans crawling gait on lubricated surfaces have been scarce, primarily due to difficulties in estimating the physical features at the nematode-gel interface. Using kinematic data and a hydrodynamic model based on lubrication theory, we calculate both the surface drag forces and the nematode's bending force while crawling on the surface of agar gels within a preexisting groove. We find that the normal and tangential surface drag coefficients during crawling are ?222 and 22, respectively, and the drag coefficient ratio is ?10. During crawling, the calculated internal bending force is time-periodic and spatially complex, exhibiting a phase lag with respect to the nematode's body bending curvature. This phase lag is largely due to viscous drag forces, which are higher during crawling as compared to swimming in an aqueous buffer solution. The spatial patterns of bending force generated during either swimming or crawling correlate well with previously described gait-specific features of calcium signals in muscle. Further, our analysis indicates that one may be able to control the motility gait of C. elegans by judiciously adjusting the magnitude of the surface drag coefficients.

Shen, X.N.; Sznitman, J.; Krajacic, P.; Lamitina, T.; Arratia, P.E.

2012-01-01

321

Tomosyn Inhibits Synaptic Vesicle Priming in Caenorhabditis elegans  

PubMed Central

Caenorhabditis elegans TOM-1 is orthologous to vertebrate tomosyn, a cytosolic syntaxin-binding protein implicated in the modulation of both constitutive and regulated exocytosis. To investigate how TOM-1 regulates exocytosis of synaptic vesicles in vivo, we analyzed C. elegans tom-1 mutants. Our electrophysiological analysis indicates that evoked postsynaptic responses at tom-1 mutant synapses are prolonged leading to a two-fold increase in total charge transfer. The enhanced response in tom-1 mutants is not associated with any detectable changes in postsynaptic response kinetics, neuronal outgrowth, or synaptogenesis. However, at the ultrastructural level, we observe a concomitant increase in the number of plasma membrane-contacting vesicles in tom-1 mutant synapses, a phenotype reversed by neuronal expression of TOM-1. Priming defective unc-13 mutants show a dramatic reduction in plasma membrane-contacting vesicles, suggesting these vesicles largely represent the primed vesicle pool at the C. elegans neuromuscular junction. Consistent with this conclusion, hyperosmotic responses in tom-1 mutants are enhanced, indicating the primed vesicle pool is enhanced. Furthermore, the synaptic defects of unc-13 mutants are partially suppressed in tom-1 unc-13 double mutants. These data indicate that in the intact nervous system, TOM-1 negatively regulates synaptic vesicle priming.

Gracheva, Elena O; Burdina, Anna O; Holgado, Andrea M; Berthelot-Grosjean, Martine; Ackley, Brian D; Hadwiger, Gayla; Nonet, Michael L; Weimer, Robby M

2006-01-01

322

Undulatory Locomotion of Caenorhabditis elegans on Wet Surfaces  

NASA Astrophysics Data System (ADS)

The physical and bio-mechanical principles that govern undulatory movement on wet surfaces have important applications in physiology, physics, and engineering. The nematode {\\it C. elegans}, with its highly stereotypical and functionally distinct sinusoidal locomotory gaits, is an excellent system in which to dissect these properties. Measurements of the main forces governing the {\\it C. elegans} crawling gait on lubricated surfaces have been scarce, primarily due to difficulties in estimating the physical features at the nematode-gel interface. Using kinematic data and a hydrodynamic model based on lubrication theory, we calculate both the surface drag forces and the nematode's bending force while crawling on the surface of agar gels. We find that the normal and tangential surface drag force coefficients during crawling are approximately 220 and 22, respectively, and the drag coefficient ratio is approximately 10. During crawling, the calculated internal bending force is time-periodic and spatially complex, exhibiting a phase lag with respect to the nematode's body bending curvature. This phase lag is largely due to viscous drag forces, which are higher during crawling as compared to swimming in an aqueous buffer solution. The spatial patterns of bending force generated during either swimming or crawling correlate well with previously described gait-specific features of calcium signals in muscle. Further, our analysis indicates that changes in the motility gait of {\\it C. elegans} is most likely due to the nematode's adaptive response to environments characterized by different drag coefficient ratios.

Shen, X. N.; Sznitman, J.; Krajacic, P.; Lamitina, T.; Arratia, P. E.

2012-06-01

323

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

324

The Redox System in C. elegans, a Phylogenetic Approach  

PubMed Central

Oxidative stress is a toxic state caused by an imbalance between the production and elimination of reactive oxygen species (ROS). ROS cause oxidative damage to cellular components such as proteins, lipids, and nucleic acids. While the role of ROS in cellular damage is frequently all that is noted, ROS are also important in redox signalling. The “Redox Hypothesis" has been proposed to emphasize a dual role of ROS. This hypothesis suggests that the primary effect of changes to the redox state is modified cellular signalling rather than simply oxidative damage. In extreme cases, alteration of redox signalling can contribute to the toxicity of ROS, as well as to ageing and age-related diseases. The nematode species Caenorhabditis elegans provides an excellent model for the study of oxidative stress and redox signalling in animals. We use protein sequences from central redox systems in Homo sapiens, Drosophila melanogaster, and Saccharomyces cerevisiae to query Genbank for homologous proteins in C. elegans. We then use maximum likelihood phylogenetic analysis to compare protein families between C. elegans and the other organisms to facilitate future research into the genetics of redox biology.

Johnston, Andrew D.; Ebert, Paul R.

2012-01-01

325

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.

Pazdernik, Nanette; Schedl, Tim

2013-01-01

326

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.

Barriere, Antoine; Felix, Marie-Anne

2007-01-01

327

Affinity Purification of Protein Complexes in C. elegans  

PubMed Central

C. elegans is a powerful metazoan model system to address fundamental questions in cell and developmental biology. Research in C. elegans has traditionally focused on genetic, physiological, and cell biological approaches. However, C. elegans is also a facile system for biochemistry: worms are easy to grow in large quantities, the functionality of tagged fusion proteins can be assessed using mutants or RNAi, and the relevance of putative interaction partners can be rapidly tested in vivo. Combining biochemistry with function-based genetic and RNA interference screens can rapidly accelerate the delineation of protein networks and pathways in diverse contexts. In this chapter, we focus on two strategies to identify protein–protein interactions: single-step immunoprecipitation and tandem affinity purification. We describe methods for growth of worms in large-scale liquid culture, preparation of worm and embryo extracts, immunoprecipitation, and tandem affinity purification. In addition, we describe methods to test specificity of antibodies, strategies for optimizing starting material, and approaches to distinguish specific from non-specific interactions.

Zanin, Esther; Dumont, Julien; Gassmann, Reto; Cheeseman, Iain; Maddox, Paul; Bahmanyar, Shirin; Carvalho, Ana; Niessen, Sherry; Yates, John R.; Oegema, Karen; Desai, Arshad

2012-01-01

328

Deubiquitylation Machinery Is Required for Embryonic Polarity in Caenorhabditis elegans  

PubMed Central

The Caenorhabditis elegans one-cell embryo polarizes in response to a cue from the paternally donated centrosome and asymmetrically segregates cell fate determinants that direct the developmental program of the worm. We have found that genes encoding putative deubiquitylating enzymes (DUBs) are required for polarization of one-cell embryos. Maternal loss of the proteins MATH-33 and USP-47 leads to variable inability to correctly establish and maintain asymmetry as defined by posterior and anterior polarity proteins PAR-2 and PAR-3. The first observable defect is variable positioning of the centrosome with respect to the cell cortex and the male pronucleus. The severity of the polarity defects correlates with distance of the centrosome from the cortex. Furthermore, polarity defects can be bypassed by mutations that bring the centrosome in close proximity to the cortex. In addition we find that polarity and centrosome positioning defects can be suppressed by compromising protein turnover. We propose that the DUB activity of MATH-33 and USP-47 stabilizes one or more proteins required for association of the centrosome with the cortex. Because these DUBs are homologous to two members of a group of DUBs that act in fission yeast polarity, we tested additional members of that family and found that another C. elegans DUB gene, usp-46, also contributes to polarity. Our finding that deubiquitylating enzymes required for polarity in Schizosaccharomyces pombe are also required in C. elegans raises the possibility that these DUBs act through an evolutionarily conserved mechanism to control cell polarity.

McCloskey, Richard J.; Kemphues, Kenneth J.

2012-01-01

329

Distribution and Transport of Cholesterol in Caenorhabditis elegans  

PubMed Central

Cholesterol transport is an essential process in all multicellular organisms. In this study we applied two recently developed approaches to investigate the distribution and molecular mechanisms of cholesterol transport in Caenorhabditis elegans. The distribution of cholesterol in living worms was studied by imaging its fluorescent analog, dehydroergosterol, which we applied to the animals by feeding. Dehydroergosterol accumulates primarily in the pharynx, nerve ring, excretory gland cell, and gut of L1–L3 larvae. Later, the bulk of dehydroergosterol accumulates in oocytes and spermatozoa. Males display exceptionally strong labeling of spermatids, which suggests a possible role for cholesterol in sperm development. In a complementary approach, we used a photoactivatable cholesterol analog to identify cholesterol-binding proteins in C. elegans. Three major and several minor proteins were found specifically cross-linked to photocholesterol after UV irradiation. The major proteins were identified as vitellogenins. rme-2 mutants, which lack the vitellogenin receptor, fail to accumulate dehydroergosterol in oocytes and embryos and instead accumulate dehydroergosterol in the body cavity along with vitellogenin. Thus, uptake of cholesterol by C. elegans oocytes occurs via an endocytotic pathway involving yolk proteins. The pathway is a likely evolutionary ancestor of mammalian cholesterol transport.

Matyash, Vitali; Geier, Christian; Henske, Annemarie; Mukherjee, Sushmita; Hirsh, David; Thiele, Christoph; Grant, Barth; Maxfield, Frederick R.; Kurzchalia, Teymuras V.

2001-01-01

330

A global analysis of C. elegans trans-splicing  

PubMed Central

Trans-splicing of one of two short leader RNAs, SL1 or SL2, occurs at the 5? ends of pre-mRNAs of many C. elegans genes. We have exploited RNA-sequencing data from the modENCODE project to analyze the transcriptome of C. elegans for patterns of trans-splicing. Transcripts of ?70% of genes are trans-spliced, similar to earlier estimates based on analysis of far fewer genes. The mRNAs of most trans-spliced genes are spliced to either SL1 or SL2, but most genes are not trans-spliced to both, indicating that SL1 and SL2 trans-splicing use different underlying mechanisms. SL2 trans-splicing occurs in order to separate the products of genes in operons genome wide. Shorter intercistronic distance is associated with greater use of SL2. Finally, increased use of SL1 trans-splicing to downstream operon genes can indicate the presence of an extra promoter in the intercistronic region, creating what has been termed a “hybrid” operon. Within hybrid operons the presence of the two promoters results in the use of the two SL classes: Transcription that originates at the promoter upstream of another gene creates a polycistronic pre-mRNA that receives SL2, whereas transcription that originates at the internal promoter creates transcripts that receive SL1. Overall, our data demonstrate that >17% of all C. elegans genes are in operons.

Allen, Mary Ann; Hillier, LaDeana W.; Waterston, Robert H.; Blumenthal, Thomas

2011-01-01

331

A transposon-related palindromic repetitive sequence from C. elegans.  

PubMed Central

A family of transposon-like sequences in the C. elegans genome is described. This family, termed the Tc6 family, consists mostly of conserved, 1.6 kb elements. Four Tc6 elements or partial elements have been cloned and the DNA sequences of three were determined. One appears to be a complete element of 1603 nucleotides, consisting of a palindrome of 765 nucleotides, with a central, non-palindromic region of 73 nucleotides. Another has an identical structure except for an internal deletion. A third is a partial element terminating at a probable internal restriction site used for cloning. A fourth clone contained portions of the Tc6 sequence juxtaposed to non-Tc6 sequences. All C. elegans strains examined contain 20-30 Tc6 elements. The ends of Tc6 elements are conserved and have sequence similarity to the ends of C. elegans transposons Tc1 and Tc3. The ends of Tc6 elements also have sequence similarity to the heptamer portion of the immunoglobulin and T-cell receptor recombination signal sequence, raising the possibility of wide phylogenetic conservation of the recombination mechanism. Tc6 elements also share sequence motifs with plant-pathogenic viroid RNA's, possibly indicative of a Tc6 RNA replicative phase. Images

Dreyfus, D H; Emmons, S W

1991-01-01

332

P Granule Assembly and Function in Caenorhabditis elegans Germ Cells  

PubMed Central

Germ granules are large, non–membrane-bound, ribonucleoprotein (RNP) organelles found in the germ line cytoplasm of most, if not all, animals. The term germ granule is synonymous with the perinuclear nuage in mouse and human germ cells. These large RNPs are complexed with germ line–specific cytoplasmic structures such as the mitochondrial cloud, intermitochondrial cement, and chromatoid bodies. The widespread presence of germ granules across species and the associated germ line defects when germ granules are compromised suggest that germ granules are key determinants of the identity and special properties of germ cells. The nematode Caenorhabditis elegans has been a very fruitful model system for the study of germ granules, wherein they are referred to as P granules. P granules contain a heterogeneous mixture of RNAs and proteins. To date, most of the known germ granule proteins across species, and all of the known P granule components in C elegans, are associated with RNA metabolism, which suggests that a main function of germ granules is posttranscriptional regulation. Here we review P granule structure and localization, P granule composition, the genetic pathway of P granule assembly, and the consequences in the germ line when P granule components are lost. The findings in C elegans have important implications for the germ granule function during postnatal germ cell differentiation in mammals.

UPDIKE, DUSTIN; STROME, SUSAN

2010-01-01

333

The genetics of pathogen avoidance in Caenorhabditis elegans.  

PubMed

Much attention is rightly focused on how microbes cause disease, but they can also affect other aspects of host physiology, including behaviour. Indeed, pathogen avoidance behaviours are seen across animal taxa and are probably of major importance in nature. Here, we review what is known about the molecular genetics underlying pathogen avoidance in the nematode Caenorhabditis elegans. In its natural environment, the soil, this animal feeds on microbes and is continuously exposed to a diverse mix of microorganisms. Nematodes that develop efficient behavioural responses that enhance their attraction to sources of food and avoidance of pathogens will have an evolutionary advantage. C. elegans can specifically detect natural products of bacteria, including surfactants (such as serrawettin) and acylated homoserine lactone autoinducers, and it can learn to avoid pathogenic species. To date, several distinct mechanisms have been shown to be involved in pathogen avoidance. They are based on G protein-like, insulin-like and neuronal serotonin signalling. We discuss recent findings on the mechanisms of pathogen recognition in C. elegans, the relationship between alternative behavioural defences and also between these and other life-history traits. We propose that the selective pressure associated with avoidance behaviours influence both pathogen and host evolution. PMID:17877707

Schulenburg, Hinrich; Ewbank, Jonathan J

2007-09-17

334

Biomechanical analysis of gait adaptation in the nematode Caenorhabditis elegans  

PubMed Central

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.

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

2010-01-01

335

Neuronal microcircuits for decision making in C. elegans.  

PubMed

The simplicity and genetic tractability of the nervous system of the nematode Caenorhabditis elegans make it an attractive system in which to seek biological mechanisms of decision making. Although work in this area remains at an early stage, four basic types paradigms of behavioral choice, a simple form of decision making, have now been demonstrated in C. elegans. A recent series of pioneering studies, combining genetics and molecular biology with new techniques such as microfluidics and calcium imaging in freely moving animals, has begun to elucidate the neuronal mechanisms underlying behavioral choice. The new research has focussed on choice behaviors in the context of habitat and resource localization, for which the neuronal circuit has been identified. Three main circuit motifs for behavioral choice have been identified. One motif is based mainly on changes in the strength of synaptic connections whereas the other two motifs are based on changes in the basal activity of an interneuron and the sensory neuron to which it is electrically coupled. Peptide signaling seems to play a prominent role in all three motifs, and it may be a general rule that concentrations of various peptides encode the internal states that influence behavioral decisions in C. elegans. PMID:22699037

Faumont, S; Lindsay, T H; Lockery, S R

2012-06-12

336

Allozyme variation in endangered Castanea pumila var. pumila.  

PubMed

Allozyme genetic variation in 12 populations of the endangered Castanea pumila var. pumila (Allegheny chinkapin), sampled across the natural range of the species in the United States, was evaluated using 11 loci from seven enzyme systems. At the species level, the percentage of polymorphic loci (Ps) was 72.7 %, the mean number of alleles per locus (As) was 1.9, the mean number of alleles per polymorphic locus (APs) was 2.3, the effective number of alleles per locus (Aes) was 1.5 and the genetic diversity (Hes) was 0.296. At the population level, Pp = 49.2 %, Ap = 1.5, Aep = 1.4, APp = 2.1 and Hep = 0.21. Most of the allozyme variation (70 %) in C. pumila var. pumila occurred within populations. Wright's gene flow rate [Nm(W)] was as low as 0.57. Population differentiation along the species range was not detected. Populations of C. pumila var. pumila in Florida had the most variable levels of genetic diversity, but populations in Virginia and Mississippi also showed high levels. Based on the results of this study, conservation management strategies are discussed. PMID:12829445

Fu, Yuqing; Dane, Fenny

2003-06-26

337

Isolation of Cryptococcus neoformans var. gattii from Eucalyptus camaldulensis in India.  

PubMed Central

Cryptococcus neoformans var. gattii has an ecological association with five Eucalyptus species: E. blakelyi, E. camaldulensis, E. gomphocephala, E. rudis, and E. tereticornis. After human infections due to C. neoformans var. gattii were diagnosed in the states of Punjab, Himachal Pradesh, and Karnataka, India, a study was undertaken to investigate the association of C. neoformans var. gattii with Indian eucalypts, especially in the state of Punjab. A total of 696 specimens collected from E. camaldulensis, E. citriodora and E. tereticornis (hybrid) trees were examined for the presence of C. neoformans var. gattii. Flowers from two trees of E. camaldulensis in the Chak Sarkar forest and one from the village of Periana near the Ferozepur area yielded five isolates of C. neoformans var. gattii. The origin of the trees could be traced to Australia, thus providing evidence that the distribution of E. camaldulensis correlated with the distribution of human cryptococcosis cases caused by C. neoformans var. gattii in northern India.

Chakrabarti, A; Jatana, M; Kumar, P; Chatha, L; Kaushal, A; Padhye, A A

1997-01-01

338

Aversive Olfactory Learning and Associative Long-Term Memory in "Caenorhabditis elegans"  

ERIC Educational Resources Information Center

|The nematode "Caenorhabditis elegans" ("C. elegans") adult hermaphrodite has 302 invariant neurons and is suited for cellular and molecular studies on complex behaviors including learning and memory. Here, we have developed protocols for classical conditioning of worms with 1-propanol, as a conditioned stimulus (CS), and hydrochloride (HCl) (pH…

Amano, Hisayuki; Maruyama, Ichiro N.

2011-01-01

339

C. elegans rrf-1 Mutations Maintain RNAi Efficiency in the Soma in Addition to the Germline  

Microsoft Academic Search

Gene inactivation through RNA interference (RNAi) has proven to be a valuable tool for studying gene function in C. elegans. When combined with tissue-specific gene inactivation methods, RNAi has the potential to shed light on the function of a gene in distinct tissues. In this study we characterized C. elegans rrf-1 mutants to determine their ability to process RNAi in

Caroline Kumsta; Malene Hansen

2012-01-01

340

Wide field-of-view lensless imaging of caenorhabditis Elegans on a chip  

Microsoft Academic Search

Wide field-of-view lensfree on-chip imaging of C. Elegans samples is demonstrated using incoherent lensless in-line holography. Digital reconstruction of these lensless holograms rapidly creates the C. Elegans images over a field-of-view of > 24 mm2.

S. O. Isikman; I. Sencan; O. Mudanyali; W. Bishara; C. Oztoprak; A. Ozcan

2010-01-01

341

A Caenorhabditis elegans Glycolipid-binding Galectin Functions in Host Defense against Bacterial Infection*  

PubMed Central

Galectins are a family of ?-galactoside-binding proteins that are widely found among animal species and that regulate diverse biological phenomena. To study the biological function of glycolipid-binding galectins, we purified recombinant Caenorhabditis elegans galectins (LEC-1–11) and studied their binding to C. elegans glycolipids. We found that LEC-8 binds to glycolipids in C. elegans through carbohydrate recognition. It has been reported that Cry5B-producing Bacillus thuringiensis strains can infect C. elegans and that the C. elegans Cry5B receptor molecules are glycolipids. We found that Cry5B and LEC-8 bound to C. elegans glycolipid-coated plates in a dose-dependent manner and that Cry5B binding to glycolipids was inhibited by the addition of LEC-8. LEC-8 is usually expressed strongly in the pharyngeal-intestinal valve and intestinal-rectal valve and is expressed weakly in intestine. However, when C. elegans were fed Escherichia coli expressing Cry5B, intestinal LEC-8::EGFP protein levels increased markedly. In contrast, LEC-8::EGFP expression triggered by Cry5B was reduced in toxin-resistant C. elegans mutants, which had mutations in genes involved in biosynthesis of glycolipids. Moreover, the LEC-8-deficient mutant was more susceptible to Cry5B than wild-type worms. These results suggest that the glycolipid-binding lectin LEC-8 contributes to host defense against bacterial infection by competitive binding to target glycolipid molecules.

Ideo, Hiroko; Fukushima, Keiko; Gengyo-Ando, Keiko; Mitani, Shohei; Dejima, Katsufumi; Nomura, Kazuya; Yamashita, Katsuko

2009-01-01

342

FMRFamide related peptide ligands activate the Caenorhabditis elegans orphan GPCR Y59H11AL.1  

Technology Transfer Automated Retrieval System (TEKTRAN)

G-protein coupled receptors (GPCRs) are ancient molecules that sense environmental and physiological signals. Currently, the majority of the predicted Caenorhabditis elegans GPCRs are orphan. Here, we describe the characterization of such an orphan C. elegans GPCR, which is categorized in the tachyk...

343

A potential biochemical mechanism underlying the influence of sterol deprivation stress on Caenorhabditis elegans longevity  

Technology Transfer Automated Retrieval System (TEKTRAN)

To investigate the biochemical mechanism for sterol-mediated alteration in aging in Caenorhabditis elegans, we established sterol depletion conditions by treating worms with azacoprostane, which reduced mean lifespan of adult C. elegans by 35%. Proteomic analyses of egg proteins from treated and un...

344

Stress Response in Caenorhabditis elegans Caused by Optical Tweezers: Wavelength, Power, and Time Dependence  

Microsoft Academic Search

Optical tweezers have emerged as a powerful technique for micromanipulation of living cells. Although the technique often has been claimed to be nonintrusive, evidence has appeared that this is not always the case. This work presents evidence that near-infrared continuous-wave laser light from optical tweezers can produce stress in Caenorhabditis elegans. A transgenic strain of C. elegans, carrying an integrated

Guenther Leitz; Erik Fällman; Simon Tuck; Ove Axner

2002-01-01

345

Hybridization between Ischnura graellsii (Vander Linder) and I. elegans (Rambur) (Odonata: Coenagrionidae): are they different species?  

Microsoft Academic Search

Two closely related damselflies, Ischnura graellsii and I. elegans, were analysed for morphological differences and reproductive isolation in the north coast of Galicia (NW Spain). We compared animals from sympatric and allopatric localities, including I. elegans from Belgium and I. graellsii from southern Spain as pure allopatric populations. A set of morphometric characters were studied by means of multivariate discriminant

LILIANA MONETTI; ROSA ANA SANCHEZ-GUILLEN; ADOLFO CORDERO RIVERA

2002-01-01

346

Hakuna Nematoda: genetic and phenotypic diversity in African isolates of Caenorhabditis elegans and C. briggsae  

Microsoft Academic Search

Caenorhabditis elegans and C. briggsae have many parallels in terms of morphology, life history and breeding system. Both species also share similar low levels of molecular diversity, although the global sampling of natural populations has been limited and geographically biased. In this study, we describe the first cultured isolates of C. elegans and C. briggsae from sub-Saharan Africa. We characterize

E S Dolgin; M-A Félix; A D Cutter

2008-01-01

347

Genetic control of programmed cell death in the Caenorhabditis elegans hermaphrodite germline  

Microsoft Academic Search

Development of the nematode Caenorhabditis elegans is highly reproducible and the fate of every somatic cell has been reported. We describe here a previously uncharacterized cell fate in C. elegans: we show that germ cells, which in hermaphrodites can differentiate into sperm and oocytes, also undergo apoptotic cell death. In adult hermaphrodites, over 300 germ cells die, using the same

Tina L. Gumienny; Eric Lambie; Erika Hartwieg; H. Robert Horvitz; Michael O. Hengartner

1999-01-01

348

Aversive Olfactory Learning and Associative Long-Term Memory in "Caenorhabditis elegans"  

ERIC Educational Resources Information Center

The nematode "Caenorhabditis elegans" ("C. elegans") adult hermaphrodite has 302 invariant neurons and is suited for cellular and molecular studies on complex behaviors including learning and memory. Here, we have developed protocols for classical conditioning of worms with 1-propanol, as a conditioned stimulus (CS), and hydrochloride (HCl) (pH…

Amano, Hisayuki; Maruyama, Ichiro N.

2011-01-01

349

Susceptibility of Caenorhabditis elegans to Burkholderia Infection Depends on Prior Diet and Secreted Bacterial Attractants  

Microsoft Academic Search

The nematode Caenorhabditis elegans may be killed by certain pathogenic bacteria and thus is a model organism for studying interactions between bacteria and animal hosts. However, growing nematodes on prey bacteria may influence their susceptibility to potential pathogens. A method of axenic nematode culture was developed to isolate and quantify interactions between C. elegans and potentially pathogenic strains of the

Vaughn S. Cooper; Wendy A. Carlson; John J. Lipuma; Niyaz Ahmed

2009-01-01

350

Susceptibility of Caenorhabditis elegans to Burkholderia infection depends on prior diet and secreted bacterial attractants  

Microsoft Academic Search

The nematode Caenorhabditis elegans may be killed by certain pathogenic bacteria and thus is a model organism for studying interactions between bacteria and animal hosts. However, growing nematodes on prey bacteria may influence their susceptibility to potential pathogens. A method of axenic nematode culture was developed to isolate and quantify interactions between C. elegans and potentially pathogenic strains of the

Vaughn S. Cooper; Wendy A. Carlson; John J. LiPuma

2009-01-01

351

Phase-dependent preference of thermosensation and chemosensation during simultaneous presentation assay in Caenorhabditis elegans  

Microsoft Academic Search

BACKGROUND: Multi-sensory integration is necessary for organisms to discriminate different environmental stimuli and thus determine behavior. Caenorhabditis elegans has 12 pairs of amphid sensory neurons, which are involved in generating behaviors such as thermotaxis toward cultivation temperature, and chemotaxis toward chemical stimuli. This arrangement of known sensory neurons and measurable behavioral output makes C. elegans suitable for addressing questions of

Ryota Adachi; Hiroshi Osada; Ryuzo Shingai

2008-01-01

352

A Neural Network Model of Chemotaxis Predicts Functions of Synaptic Connections in the Nematode Caenorhabditis elegans  

Microsoft Academic Search

The anatomical connectivity of the nervous system of the nematode Caenorhabditis elegans has been almost completely described, but determination of the neurophysiological basis of behavior in this sys- tem is just beginning. Here we used an optimization algorithm to search for patterns of connectivity suffi- cient to compute the sensorimotor transformation underlying C. elegans chemotaxis, a simple form of spatial

Nathan A. Dunn; Shawn R. Lockery; Jonathan T. Pierce-shimomura; John S. Conery

2004-01-01

353

Interpreting a Sequenced Genome: Toward a Cosmid Transgenic Library of Caenorhabditis elegans  

Microsoft Academic Search

We have generated a library of transgenic Caenorhabditis elegans strains that carry sequenced cosmids from the genome of the nematode. Each strain carries an extrachromosomal array containing a single cosmid, sequenced by the C. elegans Genome Sequencing Consortium, and a dominate Rol-6 marker. More than 500 transgenic strains representing 250 cosmids have been constructed. Collectively, these strains contain approximately 8

Diana L. Janke; Jacqueline E. Schein; Norman W. Franz; Nigel J. O'Neil; Greg P. Vatcher; Helen I. Stewart; Lynnette M. Kuervers; David L. Baillie; Ann M. Rose

2007-01-01

354

A compendium of Caenorhabditis elegans regulatory transcription factors: a resource for mapping transcription regulatory networks  

Microsoft Academic Search

BACKGROUND: Transcription regulatory networks are composed of interactions between transcription factors and their target genes. Whereas unicellular networks have been studied extensively, metazoan transcription regulatory networks remain largely unexplored. Caenorhabditis elegans provides a powerful model to study such metazoan networks because its genome is completely sequenced and many functional genomic tools are available. While C. elegans gene predictions have undergone

John S Reece-Hoyes; Bart Deplancke; Jane Shingles; Christian A Grove; Ian A Hope; Albertha JM Walhout

2005-01-01

355

TransCellular Introduction of HIV1 Protein Nef Induces Pathogenic Response in Caenorhabditis elegans  

Microsoft Academic Search

BackgroundCaenorhabditis elegans has emerged as a very powerful model for studying the host pathogen interactions. Despite the absence of a naturally occurring viral infection for C. elegans, the model is now being exploited experimentally to study the basic aspects of virus-host interplay. The data generated from recent studies suggests that the virus that infects mammalian cells does infect, replicate and

Aamir Nazir; Shreesh Raj Sammi; Pankaj Singh; Raj Kamal Tripathi; Cheryl A. Stoddart

2010-01-01

356

A potent dauer pheromone component in Caenorhabditis elegans that acts synergistically with other components  

Microsoft Academic Search

In the model organism Caenorhabditis elegans, the dauer pheromone is the primary cue for entry into the developmentally arrested, dauer larval stage. The dauer is specialized for survival under harsh environmental conditions and is considered ``nonaging'' because larvae that exit dauer have a normal life span. C. elegans constitutively secretes the dauer pheromone into its environment, enabling it to sense

Rebecca A. Butcher; Justin R. Ragains; Edward Kim; Jon Clardy

2008-01-01

357

OSM-11 Facilitates LIN12 Notch Signaling during Caenorhabditis elegans Vulval Development  

Microsoft Academic Search

Notch signaling is critical for cell fate decisions during development. Caenorhabditis elegans and vertebrate Notch ligands are more diverse than classical Drosophila Notch ligands, suggesting possible functional complexities. Here, we describe a developmental role in Notch signaling for OSM-11, which has been previously implicated in defecation and osmotic resistance in C. elegans. We find that complete loss of OSM-11 causes

Hidetoshi Komatsu; Michael Y. Chao; Jonah Larkins-Ford; Mark E. Corkins; Gerard A. Somers; Tim Tucey; Heather M. Dionne; Jamie Q. White; Khursheed Wani; Mike Boxem; Anne C. Hart

2008-01-01

358

A hub-and-spoke circuit drives pheromone attraction and social behaviour in C. elegans  

Microsoft Academic Search

Innate social behaviours emerge from neuronal circuits that interpret sensory information on the basis of an individual's own genotype, sex and experience. The regulated aggregation behaviour of the nematode Caenorhabditis elegans, a simple animal with only 302 neurons, is an attractive system to analyse these circuits. Wild social strains of C. elegans aggregate in the presence of specific sensory cues,

Evan Z. Macosko; Navin Pokala; Evan H. Feinberg; Sreekanth H. Chalasani; Rebecca A. Butcher; Jon Clardy; Cornelia I. Bargmann

2009-01-01

359

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

360

Light-sensitive neurons and channels mediate phototaxis in C. elegans  

Microsoft Academic Search

Phototaxis behavior is commonly observed in animals with light-sensing organs. C. elegans, however, is generally believed to lack phototaxis, as this animal lives in darkness (soil) and does not possess eyes. Here, we found that light stimuli elicited negative phototaxis in C. elegans and that this behavior is important for survival. We identified a group of ciliary sensory neurons as

Alex Ward; Jie Liu; Zhaoyang Feng; X Z Shawn Xu

2008-01-01

361

DRP1-mediated mitochondrial fragmentation during EGL-1-induced cell death in C. elegans  

Microsoft Academic Search

Genetic analyses in Caenorhabditis elegans have been instrumental in the elucidation of the central cell-death machinery, which is conserved from C. elegans to mammals. One possible difference that has emerged is the role of mitochondria. By releasing cytochrome c, mitochondria are involved in the activation of caspases in mammals. However, there has previously been no evidence that mitochondria are involved

Ravi Jagasia; Phillip Grote; Benedikt Westermann; Barbara Conradt

2005-01-01

362

Creation of Low-Copy Integrated Transgenic Lines in Caenorhabditis elegans  

Microsoft Academic Search

In Caenorhabditis elegans, transgenic lines are typically created by injecting DNA into the hermaphrodite germline to form multicopy extrachromosomal DNA arrays. This technique is a reliable means of expressing transgenes in C. elegans, but its use has limitations. Because extrachromosomal arrays are semistable, only a fraction of the animals in a transgenic extrachromosomal array line are transformed. In addition, because

Vida Praitis; Elizabeth Casey; David Collar; Judith Austin

363

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 ...

364

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

365

Expression profiling of five different xenobiotics using a Caenorhabditis elegans whole genome microarray  

Microsoft Academic Search

The soil nematode Caenorhabditis elegans is frequently used in ecotoxicological studies due to its wide distribution in terrestrial habitats, its easy handling in the laboratory, and its sensitivity against different kinds of stress. Since its genome has been completely sequenced, more and more studies are investigating the functional relation of gene expression and phenotypic response. For these reasons C. elegans

Kerstin Reichert; Ralph Menzel

2005-01-01

366

The neural circuits and sensory channels mediating harsh touch sensation in Caenorhabditis elegans  

Microsoft Academic Search

Most animals can distinguish two distinct types of touch stimuli: gentle (innocuous) and harsh (noxious\\/painful) touch, however, the underlying mechanisms are not well understood. Caenorhabditis elegans is a useful model for the study of gentle touch sensation. However, little is known about harsh touch sensation in this organism. Here we characterize harsh touch sensation in C. elegans. We show that

Wei Li; Lijun Kang; Beverly J. Piggott; Zhaoyang Feng; X. Z. Shawn Xu

2011-01-01

367

Signaling proteins that regulate NaCl [corrected] chemotaxis responses modulate longevity in C. elegans  

Microsoft Academic Search

The lifespan of the nematode Caenorhabditis elegans is regulated by sensory signals detected by the amphid neurons. In these neurons, C. elegans expresses at least 14 Galpha subunits and a Ggamma subunit. We have identified seven sensory Galpha subunits that modulate lifespan. Genetic experiments suggest that multiple sensory signaling pathways exist that modulate lifespan and that some G proteins function

W. J. Lans; M. P. J. Dekkers; R. K. Hukema; N. J. Bialas; M. R. Leroux; G. Jansen

2009-01-01

368

Comparative genomics and functional study of lipid metabolic genes in Caenorhabditis elegans  

PubMed Central

Background Animal models are indispensable to understand the lipid metabolism and lipid metabolic diseases. Over the last decade, the nematode Caenorhabditis elegans has become a popular animal model for exploring the regulation of lipid metabolism, obesity, and obese-related diseases. However, the genomic and functional conservation of lipid metabolism from C. elegans to humans remains unknown. In the present study, we systematically analyzed genes involved in lipid metabolism in the C. elegans genome using comparative genomics. Results We built a database containing 471 lipid genes from the C. elegans genome, and then assigned most of lipid genes into 16 different lipid metabolic pathways that were integrated into a network. Over 70% of C. elegans lipid genes have human orthologs, with 237 of 471 C. elegans lipid genes being conserved in humans, mice, rats, and Drosophila, of which 71 genes are specifically related to human metabolic diseases. Moreover, RNA-mediated interference (RNAi) was used to disrupt the expression of 356 of 471 lipid genes with available RNAi clones. We found that 21 genes strongly affect fat storage, development, reproduction, and other visible phenotypes, 6 of which have not previously been implicated in the regulation of fat metabolism and other phenotypes. Conclusions This study provides the first systematic genomic insight into lipid metabolism in C. elegans, supporting the use of C. elegans as an increasingly prominent model in the study of metabolic diseases.

2013-01-01

369

Insight into the Family of Na+/Ca2+ Exchangers of Caenorhabditis elegans.  

PubMed

Here we provide the first genome-wide in vivo analysis of the Na(+)/Ca(2+) exchanger family in the model system Caenorhabditis elegans. We source all members of this family within the Caenorhabditis genus and reconstruct their phylogeny across humans and Drosophila melanogaster. Next, we provide a description of the expression pattern for each exchanger gene in C. elegans, revealing a wide expression in a number of tissues and cell types including sensory neurons, interneurons, motor neurons, muscle cells, and intestinal tissue. Finally, we conduct a series of behavioral and functional analyses through mutant characterization in C. elegans. From these data we demonstrate that, similar to mammalian systems, the expression of Na(+)/Ca(2+) exchangers in C. elegans is skewed toward excitable cells, and we propose that C. elegans may be an ideal model system for the study of Na(+)/Ca(2+) exchangers. PMID:23893482

Sharma, Vishal; He, Chao; Sacca-Schaeffer, Julian; Brzozowski, Eric; Martin-Herranz, Daniel E; Mendelowitz, Zelda; Fitzpatrick, David A; O'Halloran, Damien M

2013-07-26

370

Role of phosphatidylinositol-4-phosphate 5? kinase (ppk-1) in ovulation of Caenorhabditis elegans  

PubMed Central

During C. elegans ovulation, the somatic gonad integrates signals from germ cells and propels a mature oocyte into the spermatheca for fertilization. Previous work suggests that phosphoinositide signaling plays important roles in C. elegans fertility. To fully understand inositol-1,4,5-trisphosphate (IP3) signaling in ovulation, we have examined the function of phosphatidylinositol-4-phosphate 5? kinase (PIP5K) in C. elegans. Our results show that the C. elegans PIP5K homolog, ppk-1, is essential for ovulation in C. elegans; ppk-1 is mainly expressed in somatic gonad, and depletion of ppk-1 expression causes defective ovulation, reduced gonad sheath contractility, and sterility. Increased IP3 signaling compensates for ppk-1 (RNAi)-induced sterility, suggesting that ppk-1 is linked to IP3 signaling. These results demonstrate that ppk-1 plays an essential role in IP3 signaling and cytoskeleton organization in somatic gonad.

Xu, Xiaojian; Guo, Haisu; Wycuff, Diane L.; Lee, Myeongwoo

2007-01-01

371

E(var)3-9 of Drosophila melanogaster Encodes a Zinc Finger Protein  

PubMed Central

The importance of a gene's natural chromatin environment for its normal expression is poignantly illustrated when a change in chromosome position results in variable gene repression, such as is observed in position effect variegation (PEV) when the Drosophila melanogaster white (w) gene is juxtaposed with heterochromatin. The Enhancer of variegation 3-9 [E(var)3-9] gene was one of over a hundred loci identified in screens for mutations that dominantly modify PEV. Haploinsufficiency for E(var)3-9 enhances wm4 variegation, as would be expected from increased heterochromatin formation. To clarify the role of E(var)3-9 in chromosome structure, the gene has been cloned and its mutant alleles characterized. The involvement of E(var)3-9 in structure determination was supported by its reciprocal effects on euchromatic and heterochromatic PEV; E(var)3-9 mutations increased expression of a variegating heterochromatic gene in two tissue types. E(var)3-9 mutations also had a recessive phenotype, maternal effect lethality, which implicated E(var)3-9 function in an essential process during embryogenesis. Both phenotypes of E(var)3-9 mutations were consistent with its proposed function in promoting normal chromosome structure. The cloning of E(var)3-9 by classical genetic methods revealed that it encodes a protein with multiple zinc fingers, but otherwise novel sequence.

Weiler, Karen S.

2007-01-01

372

A microfluidic device for the continuous culture and analysis of Caenorhabditis elegans in a toxic aqueous environment  

NASA Astrophysics Data System (ADS)

The nematode Caenorhabditis elegans (C. elegans) receives attention as a bioindicator, and the C. elegans condition has been recently analyzed using microfluidic devices equipped with an imaging system. To establish a method without an imaging system, we have proposed a novel microfluidic device with which to analyze the condition of C. elegans from the capacitance change using a pair of micro-electrodes. The device was designed to culture C. elegans, to expose C. elegans to an external stimulus, such as a chemical or toxicant, and to measure the capacitance change which indicates the condition of C. elegans. In this study, to demonstrate the capability of our device in a toxic aqueous environment, the device was applied to examine the effect of cadmium on C. elegans. Thirty L4 larval stage C. elegans were divided into three groups. One group was a control group and the other groups were exposed to cadmium solutions with concentrations of 5% and 10% LC50 for 24 h. The capacitance change and the body volume of C. elegans as a reference were measured four times and we confirmed the correlation between them. It shows that our device can analyze the condition of C. elegans without an imaging system.

Jung, Jaehoon; Nakajima, Masahiro; Tajima, Hirotaka; Huang, Qiang; Fukuda, Toshio

2013-08-01

373

Norcucurbitane triterpenoids from the fruits of Momordica charantia var. abbreviata.  

PubMed

Two new 27-norcucurbitane triterpenoids, 27-nor-3beta-hydroxy-7beta-methoxycucurbita-5,23(E)-dien-25-one (1) and 27-nor-3beta-hydroxy-5beta,19-epoxycucurbita-6,23(E)-dien-25-one (2), together with two known cucurbitane triterpenes, 23(E)-7beta-methoxycucurbita-5,23,25-trien-3beta-ol (3) and 5beta,19-epoxy-25-methoxycucurbita-6,23(E)-dien-3beta-ol (4), were isolated from the fruits of Momordica charantia var. abbreviata. Their structures were determined by analysis of spectroscopic data and comparison with the data of known analogues. PMID:23472465

Liao, Yun-Wen; Chen, Chiy-Rong; Hsu, Jue-Liang; Lin, Yun-Sheng; Cheng, Hsueh-Ling; Shih, Wen-Ling; Kuo, Yueh-Hsiung; Chang, Chi-I

2013-01-01

374

Volt/Var Control algorithm for modern distribution management system  

SciTech Connect

In this paper, a centralized Volt/Var Control (VVC) algorithm for Distribution Management System is presented. The algorithm is based on the oriented discrete coordinate descent method and takes into account all the optimization objectives of interest to distribution system analysis: minimum power loss, power demand or the number of control steps to keep the system within constraints. Although the optimization method used belongs to the traditional class of combinatorial integer programming, the algorithm provides good speed for real-time application. Numerical examples illustrate how well the VVC algorithm works for the different types of objective functions and it`s advantages in comparison with other possible optimization strategies.

Roytelman, I.; Wee, B.K.; Lugtu, R.L. [Siemens Energy and Automation, Inc., Plymouth, MN (United States). Empros Power Systems Control

1995-08-01

375

Constituents of the root wood of Austroplenckia populnea var. ovata.  

PubMed

The root wood of Austroplenckia populnea var. ovata was extracted successively with chloroform and methanol. Lapachol and dehydro-beta-lapachone were isolated from the chloroform extract, and euonine, alatusinine, wilfordine, 2-O-deacetyleuonine (1), 7-O-deacetyleuonine (2), and austronine (3) from the methanol extract. The structures of the new compounds 1-3 were elucidated by spectroscopic data interpretation. Lapachol, dehydro-beta-lapachone, euonine, alatusinine, and wilfordine are known compounds that are newly identified from root wood of Austroplenckia populnea. PMID:16933883

de Sousa, José R; Silva, Grácia D F; Miyakoshi, Tetsuo; Chen, Chen-Loung

2006-08-01

376

[Study on chemical constituents of Drosera peltata var. multisepala].  

PubMed

Chemical investigatation of Drosera peltata var. multisepala led to the isolation of eleven compounds using various chromatographic techniques. The structures of these compounds were elucidated as isoshinanolone-4-O-beta-D-glucoside (1), isoshinanolone (2), epi-isoshinanolone (3), plumbagin (4), droserone (5), droserone-5-O-glucoside (6), quercetin (7), kaempferol (8) , gossypetin-8-O-glucoside (9), 3,3'-dimethoxy ellagic acid (10), and ellagic acid (11) by their physicochemical properties and spectral data analysis. Compound 1 was a new compound. Compounds 3, 8, 10, and 11 were isolated from this plant for the first time. PMID:22737855

Li, Lin; Huang, Jin; Xu, Xianghua; Zhang, Yao; Cheng, Kejun; Yu, Peizhong

2012-01-01

377

Antitubercular triterpenes and phytosterols from Pandanus tectorius Soland. var. laevis.  

PubMed

Bioassay-guided chromatographic purification of the antitubercular chloroform extract of Pandanus tectorius Soland. var. laevis leaves afforded a new tirucallane-type triterpene, 24,24-dimethyl-5 beta-tirucall-9(11),25-dien-3-one (1), squalene and a mixture of the phytosterols stigmasterol and beta-sitosterol. Microplate Alamar Blue Assay (MABA) showed that 1 inhibited the growth of Mycobacterium tuberculosis H(37)Rv with a MIC of 64 microg/mL, while squalene and the sterol mixture have MICs of 100 and 128 microg/mL, respectively. PMID:18404330

Tan, Mario A; Takayama, Hiromitsu; Aimi, Norio; Kitajima, Mariko; Franzblau, Scott G; Nonato, Maribel G

2007-12-14

378

Production of a New Polysaccharide with Cryptoccus laurentii var. flavescens  

PubMed Central

Conditions were investigated for the production of a new gum by the yeast Cryptococcus laurentii var. flavescens NRRL Y-1401 in shaken flasks and 20-liter fermentors. The most suitable medium contained 6% commercial glucose, 0.25% autolyzed brewer's yeast, and 0.001% MnSO4 and had an initial pH of 6.5. Polysaccharide yields, as measured by the dry weight of the alcohol precipitates, were in the range of 30 to 35% based on initial glucose.

Cadmus, Martin C.; Lagoda, Adolph A.; Anderson, Ralph F.

1962-01-01

379

Caenorhabditis elegans: a model to monitor bacterial air quality  

PubMed Central

Background Low environmental air quality is a significant cause of mortality and morbidity and this question is now emerging as a main concern of governmental authorities. Airborne pollution results from the combination of chemicals, fine particles, and micro-organisms quantitatively or qualitatively dangerous for health or for the environment. Increasing regulations and limitations for outdoor air quality have been decreed in regards to chemicals and particles contrary to micro-organisms. Indeed, pertinent and reliable tests to evaluate this biohazard are scarce. In this work, our purpose was to evaluate the Caenorhaditis elegans killing test, a model considered as an equivalent to the mouse acute toxicity test in pharmaceutical industry, in order to monitor air bacterial quality. Findings The present study investigates the bacterial population in dust clouds generated during crop ship loading in harbor installations (Rouen harbor, Normandy, France). With a biocollector, airborne bacteria were impacted onto the surface of agar medium. After incubation, a replicate of the colonies on a fresh agar medium was done using a velvet. All the replicated colonies were pooled creating the "Total Air Sample". Meanwhile, all the colonies on the original plate were isolated. Among which, five representative bacterial strains were chosen. The virulence of these representatives was compared to that of the "Total Air Sample" using the Caenorhaditis elegans killing test. The survival kinetic of nematodes fed with the "Total Air Sample" is consistent with the kinetics obtained using the five different representatives strains. Conclusions Bacterial air quality can now be monitored in a one shot test using the Caenorhaditis elegans killing test.

2011-01-01

380

Characterizing temporal patterns in the swimming activity of Caenorhabditis elegans  

NASA Astrophysics Data System (ADS)

The locomotion behavior of Caenorhabditis elegans has been studied extensively to understand the respective roles of neural control and biomechanics as well as the interaction between them. In the present study, we suggest a new approach to characterize the temporal patterns in the swimming behavior of the organism. The approach is based on the branching length similarity (BLS) entropy defined on a simple branching network consisting of a single node and branches. The organism's swimming activity is recorded using a charge-coupled device (CCD) camera for 3 h at a rate of 4 frames per second. In each frame, we place 13 points as nodes, those points being distributed at equal intervals along the organism's length. Thus, the organism is represented by 13 nodes and 12 edges between nodes. By using the nodes and edges, we construct two simple networks. One is formed by connecting the center point to all other points, and the other is generated from the angles between edges. The BLS entropy values are calculated as S L for the former network and S ? for the latter. We investigate the distributions of the S L and the S ? values in the phase space of S L — S ? and compare those with the values obtained from a simulated C. elegans generated by using randomly-moving chained particles along a certain angle. The comparison revealed distinctive features of the movement patterns of C. elegans during swimming activity. In addition, we briefly discuss the application of our method to bio-monitoring systems to capture behavioral changes of test organisms before and after chemical treatment at low concentrations.

Choi, Yeontaek; Jeon, Wonju; Kang, Seung-Ho; Lee, Sang-Hee; Chon, Tae-Soo

2012-06-01

381

Proteome changes of Caenorhabditis elegans upon a Staphylococcus aureus infection  

PubMed Central

Background The success of invertebrates throughout evolution is an excellent illustration of the efficiency of their defence strategies. Caenorhabditis elegans has proven to be an appropriate model for transcriptome studies of host-pathogen interactions. The aim of this paper is to complement this knowledge by investigating the worm's response to a Staphylococcus aureus infection through a 2-dimensional differential proteomics approach. Results Different types of growth media in combination with either E. coli OP50 or Staphylococcus aureus were tested for an effect on the worm's lifespan. LB agar was chosen and C. elegans samples were collected 1 h, 4 h, 8 h and 24 h post S. aureus infection or E. coli incubation. Proteomics analyses resulted in the identification of 130 spots corresponding to a total of 108 differentially expressed proteins. Conclusions Exploring four time-points discloses a dynamic insight of the reaction against a gram-positive infection at the level of the whole organism. The remarkable upregulation after 8 h and 24 h of many enzymes involved in the citric acid cycle might illustrate the cost of fighting off an infection. Intriguing is the downregulation of chaperone molecules, which are presumed to serve a protective role. A comparison with a similar experiment in which C. elegans was infected with the gram-negative Aeromonas hydrophila reveals that merely 9% of the identified spots, some of which even exhibiting an opposite regulation, are present in both studies. Hence, our findings emphasise the complexity and pathogen-specificity of the worm's immune response and form a firm basis for future functional research. Reviewers This article was reviewed by Itai Yanai, Dieter Wolf and Torben Luebke (nominated by Walter Lutz).

2010-01-01

382

A novel non-coding DNA family in Caenorhabditis elegans.  

PubMed

Many repetitive elements, for example, SINEs, LINEs, LTR-retrotransposons and other SSRs are dispersed throughout eukaryotic genomes. To understand the biological function of these repetitive elements is of great current research interest. In this study, we report on the identification of a novel non-coding DNA family, designated CE1 family, in the nematode C. elegans genome. Some CE1 elements constituted a large palindrome sequence. The CE1 elements were interspersed at 95 sites in the C. elegans genome. Most of the CE1 elements were associated with, or were within, protein-coding genes. The sequence of the CE1 elements indicated that some could form a hairpin structure. One of the CE1 family, CE1(bs258), is located in the first intron of a novel gene, C46H11.6 which encodes a PDZ/DHR/GLGF domain protein. In gfp and lacZ reporter gene assays the CE1(bs258) element appeared to behave as an enhancer element for the expression of C46H11.6 but no effect on the expression of the opposite direction gene, pat-10 which encodes the body-wall muscle troponin C. The CE1(bs258) RNA transcript was detected by RT-PCR even when CE1(bs258) was located in an intron. We conclude that CE1 elements are involved in the expression of adjacent genes and are therefore selectively retained in the C. elegans genome. We discussed a biological function of the CE1(bs258) having many transcription factor-binding sites. PMID:17134856

Takashima, Yasuo; Bando, Tetsuya; Kagawa, Hiroaki

2006-10-14

383

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.

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

2013-01-01

384

Soft X-ray contact microscopy of nematode Caenorhabditis elegans  

NASA Astrophysics Data System (ADS)

Soft X-ray Contact Microscopy (SXCM) of Caenorhabditis elegans nematodes with typical length ~800 ? m and diameter ~30 ? m has been performed using the PALS laser source of wavelength ? = 1.314~? m and pulse duration ? (FWHM) = 400 ps. Pulsed soft X-rays were generated using molybdenum and gold targets with laser intensities I ? 1014 W/cm2. Images have been recorded on PMMA photo resists and analyzed using an atomic force microscope operating in contact mode. Cuticle features and several internal organs have been identified in the SXCM images including lateral field, cuticle annuli, pharynx, and hypodermal and neuronal cell nuclei.

Poletti, G.; Orsini, F.; Batani, D.; Bernardinello, A.; Desai, T.; Ullschmied, J.; Skala, J.; Kralikova, B.; Krousky, E.; Juha, L.; Pfeifer, M.; Kadlec, Ch.; Mocek, T.; Präg, A.; Renner, O.; Cotelli, F.; Lora Lamia, C.; Zullini, A.

2004-08-01

385

Molecular analysis of X chromosome dosage compensation in Caenorhabditis elegans.  

PubMed Central

We used a convenient quantitative dot blot assay to measure transcript levels for two X chromosome-linked genes, myo-2 and act-4, in the nematode Caenorhabditis elegans. We show that there is dosage compensation of transcript levels for these two genes between XX hermaphrodites and X0 males and that a mutation in the dpy-21 gene, postulated from genetic analysis to be involved in control of X chromosome expression, can affect these transcript levels in the manner predicted. However, we observe the dpy-21 effects only at some stages of the life cycle and not at others. These results are generally consistent with earlier genetic and molecular evidence. Images

Donahue, L M; Quarantillo, B A; Wood, W B

1987-01-01

386

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

387

Severe osteomyelitis due to the zygomycete Apophysomyces elegans.  

PubMed

We describe a previously healthy 69-year-old man presenting with osteomyelitis of the humerus due to the zygomycete Apophysomyces elegans. The infection was acquired in Aruba, The Netherlands Antilles. The skin provided the most likely portal of entry, although there was no history of a traumatic inoculation. The patient had no history of diabetes, and no underlying immune defects were found. Despite treatment with 7.9 g of amphotericin B, an interthoracoscapular amputation proved necessary to curtail the rapid spread of the fungus in this immunocompetent host. PMID:7883908

Meis, J F; Kullberg, B J; Pruszczynski, M; Veth, R P

1994-12-01

388

A diacetyl-induced quiescence in young Caenorhabditis elegans.  

PubMed

Many organisms enter quiescence in response to adverse environmental factors. Here, we show that L1 stage C. elegans entered a quiescent state after 3hours exposure to diacetyl in which movement and growth stopped for hours to days after odorant removal. Entry into quiescence was dependent on neurons affected by the osm-3 mutation, and by AWA neurons. Conversely, AWB/AWC neurons, the guanylyl cyclase ODR-1, and the TRPV-channel subunit OCR-2 inhibited entry into L1 arrest. This quiescent behavior represents an alternative use of olfactory signaling pathways besides approach or avoidance, and is a novel model in which to characterize genes implicated in quiescence. PMID:20493908

Hoffmann, Maria Christina; Sellings, Laurie H L; van der Kooy, Derek

2010-05-21

389

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

390

Posttranslational modifications of the basic peroxidase isoenzyme from Zinnia elegans  

Microsoft Academic Search

The major basic peroxidase (ZePrx) from Zinnia elegans suspension cell cultures was purified and cloned. The purification resolved ZePrxs in two isoforms (ZePrx33.44 and ZePrx34.70),\\u000a whose co-translational and post-translational modifications are characterized. Based on the N-terminal sequence obtained by\\u000a Edman degradation of mature ZePxs, it may be expected that the immature polypeptides of ZePrxs contain a signal peptide (N-terminal\\u000a pro-peptide)

Carlos Gabaldón; Laura V. Gómez-Ros; María J. López Núñez-Flores; Alberto Esteban-Carrasco; Alfonso Ros Barceló

2007-01-01

391

STDP-driven networks and the C. elegans neuronal network  

NASA Astrophysics Data System (ADS)

We study the dynamics of the structure of a formal neural network wherein the strengths of the synapses are governed by spike-timing-dependent plasticity (STDP). For properly chosen input signals, there exists a steady state with a residual network. We compare the motif profile of such a network with that of a real neural network of C. elegans and identify robust qualitative similarities. In particular, our extensive numerical simulations show that this STDP-driven resulting network is robust under variations of the model parameters.

Ren, Quansheng; Kolwankar, Kiran M.; Samal, Areejit; Jost, Jürgen

2010-09-01

392

Escherichia coli noncoding RNAs can affect gene expression and physiology of Caenorhabditis elegans  

PubMed Central

Food and other environmental factors affect gene expression and behaviour of animals. Differences in bacterial food affect the behaviour and longevity of Caenorhabditis elegans. However, no research has been carried out to investigate whether bacteria could utilize endogenous RNAs to affect C. elegans physiology. Here we show that two Escherichia coli endogenous noncoding RNAs, OxyS and DsrA, impact on the physiology of C. elegans. OxyS downregulates che-2, leading to impairment in C. elegans chemosensory behaviour and DsrA suppresses diacylglycerol lipase gene F42G9.6, leading to a decrease in longevity. We also examine some genes in the C. elegans RNA interference pathway for their possible involvement in the effects of OxyS and DsrA. Other bacteria, such as Bacillus mycoides, may also utilize its noncoding RNAs to interfere with gene expression in C. elegans. Our results demonstrate that E. coli noncoding RNAs can regulate gene expression and physiological conditions of C. elegans and indicate that noncoding RNAs might have interspecies ecological roles.

Liu, Huijie; Wang, Xueren; Wang, Horng-Dar; Wu, JinJing; Ren, Jing; Meng, Lingfeng; Wu, Qingfa; Dong, Hansheng; Wu, Jing; Kao, Tzu-Yu; Ge, Qian; Wu, Zheng-xing; Yuh, Chiou-Hwa; Shan, Ge

2012-01-01

393

Longevity and resistance to stress correlate with DNA repair capacity in Caenorhabditis elegans  

PubMed Central

DNA repair is an important mechanism by which cells maintain genomic integrity. Decline in DNA repair capacity or defects in repair factors are thought to contribute to premature aging in mammals. The nematode Caenorhabditis elegans is a good model for studying longevity and DNA repair because of key advances in understanding the genetics of aging in this organism. Long-lived C. elegans mutants have been identified and shown to be resistant to oxidizing agents and UV irradiation, suggesting a genetically determined correlation between DNA repair capacity and life span. In this report, gene-specific DNA repair is compared in wild-type C. elegans and stress-resistant C. elegans mutants for the first time. DNA repair capacity is higher in long-lived C. elegans mutants than in wild-type animals. In addition, RNAi knockdown of the nucleotide excision repair gene xpa-1 increased sensitivity to UV and reduced the life span of long-lived C. elegans mutants. These findings support that DNA repair capacity correlates with longevity in C. elegans.

Hyun, Moonjung; Lee, Jihyun; Lee, Kyungjin; May, Alfred; Bohr, Vilhelm A.; Ahn, Byungchan

2008-01-01

394

Interest Rate Risk of Banking Accounts: Measurement Using the VaR Framework  

Microsoft Academic Search

In order to measure the interest rate risk of banking accounts such as deposits and loans, this paper extends the value at risk (hereafter, VaR) analysis framework, which is useful for the risk evaluation of trading accounts. In order to apply the VaR concept derived from trading accounts to banking accounts, we should take into account the following issues: (1)

Tsukasa Yamashita; Toshinao Yoshiba; Toshihiro Yoshida

1998-01-01

395

Chemical constituents of the essential oil and anti- bacterial activity of Zingiber wrayi var. halabala  

Microsoft Academic Search

Chairgulprasert, V., Prasertsongskun, S. and Wichaporn, W. Chemical constituents of the essential oil and antibacterial activity of Zingiber wrayi var. halabala Songklanakarin J. Sci. Technol., 2005, 27(4) : 813-818 Zingiber wrayi var. halabala, a local herb from the Bala Forest in Narathiwat, was investigated for its chemical constituents and antibacterial activity. The essential oil was obtained by steam distillation of

Vanida Chairgulprasert; Somporn Prasertsongskun

396

Plant regeneration from in vitro cultured leaves of Lanzhou lily ( Lilium davidii var. unicolor)  

Microsoft Academic Search

Lanzhou lily (Lilium davidii var. unicolor) is one of the best lilies which are edible in China but the efficient shoot regeneration system has not been developed. The purpose of the present study is to establish an efficient and reproducible protocol for induction of shoots in vitro from L. davidii var. unicolor leaves. Shoot regeneration from in vitro cultured leaves

Xu LingFei; Ma FengWang; Liang Dong

2009-01-01

397

Investigation in central Italy of the possible association between Cryptococcus neoformans var. Gattii and Eucalyptus camaldulensis  

Microsoft Academic Search

The authors present a worldwide review of isolations of Cryptococcus neoformans, var. neoformans and C. neoformans var. gattii from animals and vegetation, referring in particular to the already well-known association of the former variety with Eucalyptus camaldulensis. They then review the Italian situation relative to this association and their studies carried out in Central Italy: in Latina (Lazio), Pisa, Viareggio

E. Campisi; F. Mancianti; G. Pini; E. Faggi; G. Gargani

2003-01-01

398

Molecular typing of wine yeast strains Saccharomyces bayanus var. uvarum using microsatellite markers  

Microsoft Academic Search

The Saccharomyces bayanus var. uvarum yeasts are associated with spontaneous fermentation of must. Some strains were shown to be enological yeasts of interest in different winemaking processes. The molecular typing of S. bayanus var. uvarum at the strain level has become significant for wine microbiologists. Four microsatellite loci were defined from the exploration of genomic DNA sequence of S. bayanus

I. Masneuf-Pomarède; C. Le Jeune; P. Durrens; M. Lollier; M. Aigle; D. Dubourdieu

2007-01-01

399

What do the VARs mean? Measuring the output effects of monetary policy  

Microsoft Academic Search

VARs describe the history of output and other variables following monetary shocks. To measure the effects of monetary shocks, one must add economic identifying assumptions. I specify the relative effects of anticipated and unanticipated money, and I calculate how VAR-based measures of the effect of money on output change as one varies this assumption. The anticipated\\/unanticipated assumption influences measured output

John H. Cochrane

1998-01-01

400

Biological activity of l-2-azetidinecarboxylic acid, isolated from Polygonatum odoratum var. pluriflorum, against several algae  

Microsoft Academic Search

The biological activities of an aqueous fraction extracted from Polygonatum odoratum var. pluriflorum Owhi and of l-2-azetidinecarboxylic acid (AZC), purified from the extract, on the growth of several types of algae were tested. The aqueous fraction was prepared by methanol extraction of P. odoratum var. pluriflorum rhizomes followed by reverse partitioning with butanol. The aqueous extraction inhibited growth of the

Jin-Seog Kim; Jin-Cheol Kim; Sunog Lee; Byung-Hoi Lee; Kwang Yun Cho

2006-01-01

401

Surirella sparsipunctata Hustedt and S. sparsipunctata var. laevis Hustedt (Bacillariophyceae), a light and electron microscopical study  

Microsoft Academic Search

Three populations of S. sparsipunctata from the eastern coast of Lake Tanganyika were studied by light and electron microscopy. We found no distinct differences between the type variety and var. laevis; therefore we propose to include the var. laevis with the typical variety. An amended description of S. sparsipunctata based on LM and SEM observations is given.

Christine Cocquyt; Wim Vyverman

1993-01-01

402

Saccharomyces bayanus var. uvarum in Tokaj wine-making of Slovakia and Hungary  

Microsoft Academic Search

Using genetic hybridisation analysis and molecular karyotyping we revealed an association of Saccharomyces bayanus var. uvarum species with Tokaj wine-making. Along with identification of Saccharomyces strains isolated by E. Minárik in Slovakia, the composition of Tokaj populations in Hungary was studied. Twenty-eight Hungarian Saccharomyces strains were analysed in terms of karyotype. The majority of strains belong to S. bayanus var.

G. I. Naumov; E. S. Naumova; Z. Antunovics; M. Sipiczki

2002-01-01

403

Essential oil constituents of different organs of fennel (Foeniculum vulgare var. vulgare)  

Microsoft Academic Search

Essential oil constituents of different organs of fennel (Foeniculum vulgare var. vulgare). The fennel (Foeniculum vulgare Mill.var. vulgare) is an annual herbaceous plant, whose seeds are very used in the homemade medicine and pharmaceutical industry. The fennel seeds produce yellow-clear aromatic essential oil, used in the production of several licorous drinks and of perfumery, with action carminative and stimulant. Therefore,

R. Facanali; S. P. Brazil

404

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.

2012-01-01

405

Effects of abiotic and biotic elicitors on growth and isoflavonoid accumulation in Pueraria candollei var. candollei and P. candollei var. mirifica cell suspension cultures  

Microsoft Academic Search

This study demonstrates the effects of various concentrations of abiotic and biotic elicitors on the cell growth and isoflavonoid\\u000a accumulation of P. candollei var. mirifica (PM) and P. candollei var. candollei (PC) cell suspension cultures. The two plant varieties exhibited different growth responses and varied isoflavonoid accumulation\\u000a after the addition of elicitors. Copper sulfate, methyl jasmonate (MeJA), and yeast extract

Sirintra Korsangruang; Noppamas Soonthornchareonnon; Yupyn Chintapakorn; Promchit Saralamp; Sompop Prathanturarug

2010-01-01

406

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

407

Coordinated static VAr compensators and power system stabilizers for damping power system oscillations  

SciTech Connect

Technical advantages of coordinating static VAr compensators and power system stabilizers for damping inertial and torsional modes of steam turbine generators are demonstrated. A new control concept for Static VAr Compensators based on using modal speeds as feedback signals, is presented. The concept enables a static VAr compensator to damp all the oscillatory modes as well as controlling the system voltage. A comparison is made made between the cases where either modal speeds or generator speed deviations are used as the stabilizing signals of static VAr compensators. The present study shows that coordination of static compensators and power system stabilizers can significantly increase power system dampings as compared with cases where either static VAr compensators or power system stabilizers are used to damp system oscillations. This study is performed on System-1 of the second IEEE benchmark for SSR studies, using an eigenvalue method. The analytical results are verified by detailed digital computer simulation studies, using the BPA's Electromagnetic Transients Program (EMTP).

Hamouda, R.M.; Iravani, M.R.; Hackam, R.

1987-11-01

408

A Two-Gene Balance Regulates Salmonella Typhimurium Tolerance in the Nematode Caenorhabditis elegans  

PubMed Central

Lysozymes are antimicrobial enzymes that perform a critical role in resisting infection in a wide-range of eukaryotes. However, using the nematode Caenorhabditis elegans as a model host we now demonstrate that deletion of the protist type lysozyme LYS-7 renders animals susceptible to killing by the fatal fungal human pathogen Cryptococcus neoformans, but, remarkably, enhances tolerance to the enteric bacteria Salmonella Typhimurium. This trade-off in immunological susceptibility in C. elegans is further mediated by the reciprocal activity of lys-7 and the tyrosine kinase abl-1. Together this implies a greater complexity in C. elegans innate immune function than previously thought.

Marsh, Elizabeth K.; van den Berg, Maaike C. W.; May, Robin C.

2011-01-01

409

Evolution of host innate defence: insights from C. elegans and primitive invertebrates  

PubMed Central

Preface The genetically tractable model organism Caenorhabditis elegans was first used to model bacterial virulence in vivo a decade ago. Since then, great strides have been made in the identification of host response pathways that are involved in the defence against infection. Strikingly, C. elegans seems to detect and respond to infection without the involvement of its Toll-like receptor homologue, in contrast to the well-established role for these proteins in innate immunity in mammals. What, therefore, do we know about host defence mechanisms in C. elegans, and what can they tell us about innate immunity in higher organisms?

Irazoqui, Javier E.; Urbach, Jonathan M.; Ausubel, Frederick M.

2010-01-01

410

Catabolic pathways of glucose in Bacillus circulans var. alkalophilus.  

PubMed

Enzymes and the metabolic pathways of glucose catabolism of Bacillus circulans var. alkalophilus were studied. The metabolism of the microbe was mixed acid fermentative yielding mainly acetic and formic acids as end products from glucose. It was estimated that B. circulans var. alkalophilus partitions 90%-93% of the carbon from glucose into the Embden-Meyerhof-Parnas (EMP) pathway and 7%-10% into the hexose monophosphate (HMP) and Entner-Doudoroff (ED) pathways. Rather low activities of glucose dehydrogenase and gluconokinase appeared in the early logarithmic and late stationary phases, whereas NADH oxidase was markedly high. This result can be explained by a demand to reduce NADH to NAD+ for the EMP pathway; when acetic and formic acids are produced, no NADH is regenerated to NAD+, which is required in the early steps of EMP and HMP pathways. A small percentage (1.6%-2.4%) of the total CO2 was formed from (6-C) of glucose, which means that the tricarboxylic acid cycle was functional but its contribution was insignificant. Large differences do not seem to exist between alkaliphilic and neutrophilic bacilli in the use of glucose pathways. PMID:10591018

Paavilainen, S; Oinonen, S; Korpela, T

1999-11-01

411

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

412

Our evolving view of Wnt signaling in C. elegans  

PubMed Central

In this commentary, we discuss how our recent paper by Yang et al. contributes a new wrinkle to the already somewhat curious Wnt signaling pathway in C. elegans. We begin with a historical perspective on the Wnt pathway in the worm, followed by a summary of the key salient point from Yang et al., 2011, namely demonstration of mutually inhibitory binding of a ?-catenin SYS-1 to the N-terminus and another ?-catenin WRM-1 to the C-terminus of the TCF protein POP-1, and a plausible structural explanation for these differential binding specificities. The mutually inhibitory binding creates one population of POP-1 that is bound by WRM-1, phosphorylated by the NLK kinase and exported from the nucleus, and another bound by coactivator SYS-1 that remains in the nucleus. We speculate on the evolutionary history of the four ?-catenins in C. elegans and suggest a possible link between multiple ?-catenin gene duplications and the requirement to reduce nuclear POP-1 levels to activate Wnt target genes.

Robertson, Scott M.; Lin, Rueyling

2012-01-01

413

3-D worm tracker for freely moving C. elegans.  

PubMed

The manner in which the nervous system regulates animal behaviors in natural environments is a fundamental issue in biology. To address this question, C. elegans has been widely used as a model animal for the analysis of various animal behaviors. Previous behavioral assays have been limited to two-dimensional (2-D) environments, confining the worm motion to a planar substrate that does not reflect three-dimensional (3-D) natural environments such as rotting fruits or soil. Here, we develop a 3-D worm tracker (3DWT) for freely moving C. elegans in 3-D environments, based on a stereoscopic configuration. The 3DWT provides us with a quantitative trajectory, including the position and movement direction of the worm in 3-D. The 3DWT is also capable of recording and visualizing postures of the moving worm in 3-D, which are more complex than those in 2-D. Our 3DWT affords new opportunities for understanding the nervous system function that regulates animal behaviors in natural 3-D environments. PMID:23437394

Kwon, Namseop; Pyo, Jaeyeon; Lee, Seung-Jae; Je, Jung Ho

2013-02-21

414

Characterization of seven genes affecting Caenorhabditis elegans hindgut development.  

PubMed Central

We have identified and characterized 12 mutations in seven genes that affect the development of the Caenorhabditis elegans hindgut. We find that the mutations can disrupt the postembryonic development of the male-specific blast cells within the hindgut, the hindgut morphology in both males and hermaphrodites, and in some cases, the expression of a hindgut marker in hermaphrodite animals. Mutations in several of the genes also affect viability. On the basis of their mutant phenotypes, we propose that the genes fall into four distinct classes: (1) egl-5 is required for regional identity of the tail; (2) sem-4 is required for a variety of ectodermal and mesodermal cell types, including cells in the hindgut; (3) two genes, lin-49 and lin-59, affect development of many cells, including hindgut; and (4) three genes, mab-9, egl-38, and lin-48, are required for patterning fates within the hindgut, making certain hindgut cells different from others. We also describe a new allele of the Pax gene egl-38 that is temperature sensitive and affects the conserved beta-hairpin of the EGL-38 paired domain. Our results suggest that a combination of different factors contribute to normal C. elegans hindgut development.

Chamberlin, H M; Brown, K B; Sternberg, P W; Thomas, J H

1999-01-01

415

Metabolism and aging in the nematode Caenorhabditis elegans.  

PubMed

Research into the causes of aging has greatly increased in recent years. Much of this interest is due to the discovery of genes in a variety of model organisms that appear to modulate aging. Studies of long-lived mutants can potentially provide valuable insights into the fundamental mechanisms of aging. While there are many advantages to the use of model organisms to study aging it is also important to consider the limitations of these systems, particularly because ectothermic (poikilothermic) organisms can survive a far greater metabolic depression than humans. As such, the consideration of only chronological longevity when assaying for long-lived mutants provides a limited perspective on the mechanisms by which longevity is increased. Additional physiological processes, such as metabolic rate, must also be assayed to provide true insight into the aging process. This is especially true in the nematode Caenorhabditis elegans, which has the natural ability to enter into a metabolically reduced state in which it can survive many times longer than its normal lifetime. The extended longevity of at least some long-lived C. elegans mutants may be due to a reduction in metabolic rate, rather than an alteration of a metabolically independent genetic mechanism specific for aging. PMID:12208344

Van Voorhies, Wayne A

2002-09-01

416

Structural analysis of N-linked glycans in Caenorhabditis elegans.  

PubMed

Caenorhabditis elegans is an excellent model for morphogenetic research. However, little information is available on the structure of cell-surface glycans in C. elegans, although several lines of evidence have suggested a role for these glycans in cell-cell interactions during development. In this study, we analyzed N-glycan structures. Oligosaccharides liberated by hydrazinolysis from a total membrane fraction were labeled by pyridylamination, and around 90% of the N-glycans were detected as neutral oligosaccharides. The most dominant structure was Man(alpha)1-6(Man(alpha)1-3)Man(beta)1-4GlcNAc(beta)1-4GlcNAc, which is commonly found in insects. Branching structures of major oligomannose-type glycans were the same as those found in mammals. Structures that had a core fucose or non-reducing end N-acetylglucosamine were also identified, but ordinary complex-type glycans with N-acetyllactosamine were not detected as major components. PMID:12038976

Natsuka, Shunji; Adachi, Jiro; Kawaguchi, Masahumi; Nakakita, Shin-ichi; Hase, Sumihiro; Ichikawa, Akira; Ikura, Koji

2002-06-01

417

The Genetics of Levamisole Resistance in the Nematode CAENORHABDITIS ELEGANS  

PubMed Central

We have characterized a small group of genes (13 loci) in the nematode Caenorhabditis elegans that, when mutated, confer resistance to the potent anthelmintic levamisole. Mutants at the 7 loci conferring the most extreme resistance generally possess almost identical visible and pharmacological phenotypes: uncoordinated motor behavior, most severe in early larval life, extreme resistance to cholinergic agonists and sensitivity to hypo-osmotic shock. Mutants with exceptional phenotypes suggest possible functions for several of the resistance loci. The most extreme mutants can readily be selected by their drug resistance (211 mutants, as many as 74 alleles of one gene). The more common resistance loci are likely to be unessential genes, while loci identified by only a few alleles may be essential genes or genes conferring resistance only when mutated in a special way. We propose that these mutants represent a favorable system for understanding how a small group of related genes function in a simple animal. The extreme drug resistance of these mutants makes them useful tools for the genetic manipulation of C. elegans. And, as the most resistant class of mutants might lack pharmacologically functional acetylcholine receptors (Lewis et al. 1980), these mutants may also be of some neurobiological significance.

Lewis, James A.; Wu, C.-H.; Berg, Howard; Levine, Joseph H.

1980-01-01

418

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

419

3-D Worm Tracker for Freely Moving C. elegans  

PubMed Central

The manner in which the nervous system regulates animal behaviors in natural environments is a fundamental issue in biology. To address this question, C. elegans has been widely used as a model animal for the analysis of various animal behaviors. Previous behavioral assays have been limited to two-dimensional (2-D) environments, confining the worm motion to a planar substrate that does not reflect three-dimensional (3-D) natural environments such as rotting fruits or soil. Here, we develop a 3-D worm tracker (3DWT) for freely moving C. elegans in 3-D environments, based on a stereoscopic configuration. The 3DWT provides us with a quantitative trajectory, including the position and movement direction of the worm in 3-D. The 3DWT is also capable of recording and visualizing postures of the moving worm in 3-D, which are more complex than those in 2-D. Our 3DWT affords new opportunities for understanding the nervous system function that regulates animal behaviors in natural 3-D environments.

Kwon, Namseop; Pyo, Jaeyeon; Lee, Seung-Jae; Je, Jung Ho

2013-01-01

420

Microbeam irradiation of C. elegans nematode in microfluidic channels.  

PubMed

To perform high-throughput studies on the biological effects of ionizing radiation in vivo, we have implemented a microfluidic tool for microbeam irradiation of Caenorhabditis elegans. The device allows the immobilization of worms with minimal stress for a rapid and controlled microbeam irradiation of multiple samples in parallel. Adapted from an established design, our microfluidic clamp consists of 16 tapered channels with 10-?m-thin bottoms to ensure charged particle traversal. Worms are introduced into the microfluidic device through liquid flow between an inlet and an outlet, and the size of each microchannel guarantees that young adult worms are immobilized within minutes without the use of anesthesia. After site-specific irradiation with the microbeam, the worms can be released by reversing the flow direction in the clamp and collected for analysis of biological endpoints such as repair of radiation-induced DNA damage. For such studies, minimal sample manipulation and reduced use of drugs such as anesthetics that might interfere with normal physiological processes are preferable. By using our microfluidic device that allows simultaneous immobilization and imaging for irradiation of several whole living samples on a single clamp, here we show that 4.5-MeV proton microbeam irradiation induced DNA damage in wild-type C. elegans, as assessed by the formation of Rad51 foci that are essential for homologous repair of radiation-induced DNA damage. PMID:23942865

Buonanno, M; Garty, G; Grad, M; Gendrel, M; Hobert, O; Brenner, D J

2013-08-13

421

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

422

Selenium induces cholinergic motor neuron degeneration in Caenorhabditis elegans  

PubMed Central

Selenium is an essential micronutrient required for cellular antioxidant systems, yet at higher doses it induces oxidative stress. Additionally, in vertebrates environmental exposures to toxic levels of selenium can cause paralysis and death. Here we show that selenium-induced oxidative stress leads to decreased cholinergic signaling and degeneration of cholinergic neurons required for movement and egg-laying in Caenorhabditis elegans. Exposure to high levels of selenium leads to proteolysis of a soluble muscle protein through mechanisms suppressible by two pharmacological agents, levamisole and aldicarb which enhance cholinergic signaling in muscle. In addition, animals with reduction-of-function mutations in genes encoding post-synaptic levamisole-sensitive acetylcholine receptor subunits or the vesicular acetylcholine transporter developed impaired forward movement faster during selenium-exposure than normal animals, again confirming that selenium reduces cholinergic signaling. Finally, the antioxidant reduced glutathione, inhibits selenium-induced reductions in egg-laying through a cellular protective mechanism dependent on the C. elegans glutaredoxin, GLRX-21. These studies provide evidence that the environmental toxicant selenium induces neurodegeneration of cholinergic neurons through depletion of glutathione, a mechanism linked to the neuropathology of Alzheimer’s disease, amyotrophic lateral sclerosis, and Parkinson’s disease.

Estevez, Annette O.; Mueller, Catherine L.; Morgan, Kathleen L.; Szewczyk, Nathaniel J.; Teece, Luke; Miranda-Vizuete, Antonio; Estevez, Miguel

2012-01-01

423

From Modes to Movement in the Behavior of Caenorhabditis elegans  

PubMed Central

Organisms move through the world by changing their shape, and here we explore the mapping from shape space to movements in the nematode Caenorhabditis elegans as it crawls on an agar plate. We characterize the statistics of the trajectories through the correlation functions of the orientation angular velocity, orientation angle and the mean-squared displacement, and we find that the loss of orientational memory has significant contributions from both abrupt, large amplitude turning events and the continuous dynamics between these events. Further, we discover long-time persistence of orientational memory in the intervals between abrupt turns. Building on recent work demonstrating that C. elegans movements are restricted to a low-dimensional shape space, we construct a map from the dynamics in this shape space to the trajectory of the worm along the agar. We use this connection to illustrate that changes in the continuous dynamics reveal subtle differences in movement strategy that occur among mutants defective in two classes of dopamine receptors.

Stephens, Greg J.; Johnson-Kerner, Bethany; Bialek, William; Ryu, William S.

2010-01-01

424

PTL-1 regulates neuronal integrity and lifespan in C. elegans.  

PubMed

Protein with tau-like repeats (PTL-1) is the sole Caenorhabditis elegans homolog of tau and MAP2, which are members of the mammalian family of microtubule-associated proteins (MAPs). In mammalian neurons, tau and MAP2 are segregated, with tau being mainly localised to the axon and MAP2 mainly to the dendrite. In particular, tau plays a crucial role in pathology, as elevated levels lead to the formation of tau aggregates in many neurodegenerative conditions including Alzheimer's disease. We used PTL-1 in C. elegans to model the biological functions of a tau-like protein without the complication of functional redundancy that is observed among the mammalian MAPs. Our findings indicate that PTL-1 is important for the maintenance of neuronal health as animals age, as well as in the regulation of whole organism lifespan. In addition, gene dosage of PTL-1 is crucial because variations from wild-type levels are detrimental. We also observed that human tau is unable to robustly compensate for loss of PTL-1, although phenotypes observed in tau transgenic worms are dependent on the presence of endogenous PTL-1. Our data suggest that some of the effects of tau pathology result from the loss of physiological tau function and not solely from a toxic gain-of-function due to accumulation of tau. PMID:23525010

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

2013-03-22

425

Transformation of 1- and 2-methylnaphthalene by Cunninghamella elegans  

SciTech Connect

Cunninghamella elegans metabolized 1- and 2-methylnaphthalene primarily at the methyl group to form 1- and 2-hydroxymethylnaphthalene, respectively. Other compounds isolated and identified were 1- and 2-naphthoic acids, 5-hydroxy-1-naphthoic acid, 5-hydroxy-2-naphthoic acid, 6-hydroxy-2-naphthoic acid, and phenolic derivatives of 1- and 2-methylnaphthalene. The metabolites were isolated by thin-layer and reverse-phase high-presure liquid chromatography and characterized by the application of UV-visible absorption, /sup 1/H nuclear magnetic resonance, and mass spectral techniques. Experiments with (8-/sup 14/C)2-methylnaphthalene indicated that over a 72-h period, 9.8% of 2-methylnaphthalene was oxidized to metabolic products. The ratio of organic-soluble to water-soluble metabolites at 2 h was 92:8, and at 72 h it was 41:59. Enzymatic treatment of the 48-h aqueous phase with either ..beta..-glucuronidase or arylsufatase released 60% of the metabolites of 2-methylnaphthalene that were extractable with ethyl acetate. In both cases, the major conjugates released were 5-hydroxy-2-naphthoic acid and 6-hydroxy-2-naphthoic acid. The ratio of the water-soluble glucuronide conjugates to sulfate conjugates was 1:1. Incubation of C. elegans with 2-methylnaphthalene under an /sup 18/O/sub 2/ atmosphere and subsequent mass spectral analysis of 2-hydroxymethylnaphthalene indicated that hydroxylation of the methyl group is catalyzed by a monooxygenase. 23 references.

Cerniglia, C.E.; Lambert, K.J.; Miller, D.W.; Freeman, J.P.

1984-01-01

426

[Physiological and molecular control of lipid accumulation in Caenorhabditis elegans].  

PubMed

Fat storage is a complex physiological process, and model organism of Caenorhabditis elegans has already been explored as an important model to study lipid accumulation. The lipid particles or fatty acid can be stained or labeled with Sudan Black B or Neil Red. The metabolism pathways for fatty acid synthesis and breakdown in nematodes are almost identical to those in other organisms, and functions of many genes encoding the key regulation enzymes have been identified. At least four central regulation pathways are involved in the fat storage control in nematodes: insulin and TGF-beta signaling pathway, sbp-1/mdt-15 mediated pathway, nhr-49 mediated pathway, and TOR and hexosamine pathway. Moreover, neurotransmitters 5-HT, dopamine, and glutamate were found to participate in the control of lipid accumulation. In addition, involvement of tub-1 and bbs-1 in neuronal control of fat storage suggest the possibly important roles of amphid structure and sensory neurons in regulating lipid accumulation. The data obtained in C. elegans on fat storage control will contribute largely to the study on metabolism related diseases, such as obesity, in human beings. PMID:19558141

Xu, Xue-Mei; Wang, Da-Yong

2009-04-01

427

Anabolic function of phenylalanine hydroxylase in Caenorhabditis elegans.  

PubMed

In humans, liver phenylalanine hydroxylase (PAH) has an established catabolic function, and mutations in PAH cause phenylketonuria, a genetic disease characterized by neurological damage, if not treated. To obtain novel evolutionary insights and information on molecular mechanisms operating in phenylketonuria, we investigated PAH in the nematode Caenorhabditis elegans (cePAH), where the enzyme is coded by the pah-1 gene, expressed in the hypodermis. CePAH presents similar molecular and kinetic properties to human PAH [S(0.5)(L-Phe) approximately 150 microM; K(m) for tetrahydrobiopterin (BH(4)) approximately 35 microM and comparable V(max)], but cePAH is devoid of positive cooperativity for L-Phe, an important regulatory mechanism of mammalian PAH that protects the nervous system from excess L-Phe. Pah-1 knockout worms show no obvious neurological defects, but in combination with a second cuticle synthesis mutation, they display serious cuticle abnormalities. We found that pah-1 knockouts lack a yellow-orange pigment in the cuticle, identified as melanin by spectroscopic techniques, and which is detected in C. elegans for the first time. Pah-1 mutants show stimulation of superoxide dismutase activity, suggesting that cuticle melanin functions as oxygen radical scavenger. Our results uncover both an important anabolic function of PAH and the change in regulation of the enzyme along evolution. PMID:18460651

Calvo, Ana C; Pey, Angel L; Ying, Ming; Loer, Curtis M; Martinez, Aurora

2008-05-06

428

High-throughput expression of C. elegans proteins.  

PubMed

Proteome-scale studies of protein three-dimensional structures should provide valuable information for both investigating basic biology and developing therapeutics. Critical for these endeavors is the expression of recombinant proteins. We selected Caenorhabditis elegans as our model organism in a structural proteomics initiative because of the high quality of its genome sequence and the availability of its ORFeome, protein-encoding open reading frames (ORFs), in a flexible recombinational cloning format. We developed a robotic pipeline for recombinant protein expression, applying the Gateway cloning/expression technology and utilizing a stepwise automation strategy on an integrated robotic platform. Using the pipeline, we have carried out heterologous protein expression experiments on 10,167 ORFs of C. elegans. With one expression vector and one Escherichia coli strain, protein expression was observed for 4854 ORFs, and 1536 were soluble. Bioinformatics analysis of the data indicates that protein hydrophobicity is a key determining factor for an ORF to yield a soluble expression product. This protein expression effort has investigated the largest number of genes in any organism to date. The pipeline described here is applicable to high-throughput expression of recombinant proteins for other species, both prokaryotic and eukaryotic, provided that ORFeome resources become available. PMID:15489332

Luan, Chi-Hao; Qiu, Shihong; Finley, James B; Carson, Mike; Gray, Rita J; Huang, Wenying; Johnson, David; Tsao, Jun; Reboul, Jérôme; Vaglio, Philippe; Hill, David E; Vidal, Marc; Delucas, Lawrence J; Luo, Ming

2004-10-01

429

Function, targets, and evolution of Caenorhabditis elegans piRNAs.  

PubMed

Piwi-interacting RNAs (piRNAs) are small RNAs required to maintain germline integrity and fertility, but their mechanism of action is poorly understood. Here we demonstrate that Caenorhabditis elegans piRNAs silence transcripts in trans through imperfectly complementary sites. Target silencing is independent of Piwi endonuclease activity or "slicing." Instead, piRNAs initiate a localized secondary endogenous small interfering RNA (endo-siRNA) response. Endogenous protein-coding gene and transposon transcripts exhibit Piwi-dependent endo-siRNAs at sites complementary to piRNAs and are derepressed in Piwi mutants. Genomic loci of piRNA biogenesis are depleted of protein-coding genes and tend to overlap the start and end of transposons in sense and antisense, respectively. Our data suggest that nematode piRNA clusters are evolving to generate piRNAs against active mobile elements. Thus, piRNAs provide heritable, sequence-specific triggers for RNA interference in C. elegans. PMID:22700655

Bagijn, Marloes P; Goldstein, Leonard D; Sapetschnig, Alexandra; Weick, Eva-Maria; Bouasker, Samir; Lehrbach, Nicolas J; Simard, Martin J; Miska, Eric A

2012-06-14

430

Distribution and movement of Caenorhabditis elegans on a thermal gradient.  

PubMed

To analyze thermal responses of Caenorhabditis elegans in detail, distribution of a worm population and movement of individual worms were examined on a linear, reproducible and broad temperature gradient. Assay methods were improved compared with those reported previously to ensure good motility and dispersion of worms. Well-fed, wild-type worms distributed over a wide temperature range of up to 10 degrees C, and, within this range, worms migrated in both directions of the gradient at similar frequencies without any specific response to the growth temperature in most cases. By contrast, worms migrated down the gradient if put in a region warmer than the warm boundary of distribution. The distribution range changed depending on the growth temperature and starvation, but active avoidance of a starvation temperature was not detected. These findings contradict previous hypotheses of taxis or migration to the growth temperature in association with food and instead indicate avoidance of a warm temperature. Our results favor a model for thermal response of C. elegans that postulates a single drive based on warm sensation rather than downward and upward drives in the physiological temperature range. Mutants in ttx-3, tax-2, tax-4 or egl-4 genes showed abnormal thermal responses, suggesting that these genes are involved in warm avoidance. Laser ablation and gene expression studies suggest that AFD neurons are not important, and tax-4 expression in neurons other than AFD is required, for warm avoidance. PMID:12819265

Yamada, Yohko; Ohshima, Yasumi

2003-08-01

431

Functional analysis of a C. elegans trans-splice acceptor.  

PubMed Central

The rol-6 gene is trans-spliced to the 22 nt leader, SL1, 173 nt downstream of the transcription start. We have analyzed splicing in transformants carrying extrachromosomal arrays of rol-6 with mutations in the trans-splice acceptor site. This site is a close match to the consensus, UUUCAG, that is highly conserved in both trans-splice and intron acceptor sites in C. elegans. When the trans-splice site was inactivated by mutating the perfectly-conserved AG, trans-splicing still occurred, but at a cryptic site 20 nt upstream. We tested the frequency with which splicing switched from the normal site to the cryptic site when the pyrimidines at this site were changed to A's. Since most C. elegans 3' splice sites lack an obvious polypyrimidine tract, we hypothesized that these four pyrimidines might play this role, and indeed mutation of these bases caused splicing to switch to the cryptic site. We also demonstrated that a major reason the downstream site is normally favored is because it occurs at a boundary between A+U rich and non-A+U rich RNA. When the RNA between the two splice sites was made less A+U rich, splicing occurred preferentially at the upstream site. Images

Conrad, R; Liou, R F; Blumenthal, T

1993-01-01

432

Comparative Developmental Expression Profiling of Two C. elegans Isolates  

PubMed Central

Gene expression is known to change during development and to vary among genetically diverse strains. Previous studies of temporal patterns of gene expression during C. elegans development were incomplete, and little is known about how these patterns change as a function of genetic background. We used microarrays that comprehensively cover known and predicted worm genes to compare the landscape of genetic variation over developmental time between two isolates of C. elegans. We show that most genes vary in expression during development from egg to young adult, many genes vary in expression between the two isolates, and a subset of these genes exhibit isolate-specific changes during some developmental stages. This subset is strongly enriched for genes with roles in innate immunity. We identify several novel motifs that appear to play a role in regulating gene expression during development, and we propose functional annotations for many previously unannotated genes. These results improve our understanding of gene expression and function during worm development and lay the foundation for linkage studies of the genetic basis of developmental variation in gene expression in this important model organism.

Capra, Emily J.; Skrovanek, Sonja M.; Kruglyak, Leonid

2008-01-01

433

Isolation, Culture, and Fermentation Characteristics of Selenomonas ruminantium var. bryanti var. n. from the Rumen of Sheep  

PubMed Central

Large forms of Selenomonas sp. were isolated from the sheep rumen on a rumen fluid-glucose-agar medium by using a differential centrifugation technique to purify the inoculum. The cells from the six isolated strains were curved, gram-negative, strictly anaerobic crescents, and rapidly motile by flagella attached to the concave side of the cell. One or more of the volatile fatty acids were essential for growth. None of the strains produced indole or reduced nitrate. All strains grew on fructose, glucose, mannose, cellobiose, maltose, sucrose, and salicin. Fermentation end products from glucose were mainly lactate, acetate, propionate, and formate. Small amounts of succinate were formed. The final pH in a glucose medium ranged between 4.3 and 4.5. On the basis of the sugar fermentation characteristics and the capacity to form hydrogen sulfide from cysteine, it is suggested that one of the strains is a large form of Selenomonas ruminantium. The other five strains are designated S. ruminantium var. bryanti, var. n. Images

Prins, R. A.

1971-01-01

434

Genetic diversity of expressed Plasmodium falciparum var genes from Tanzanian children with severe malaria  

PubMed Central

Background Severe malaria has been attributed to the expression of a restricted subset of the var multi-gene family, which encodes for Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1). PfEMP1 mediates cytoadherence and sequestration of infected erythrocytes into the post-capillary venules of vital organs such as the brain, lung or placenta. var genes are highly diverse and can be classified in three major groups (ups A, B and C) and two intermediate groups (B/A and B/C) based on the genomic location, gene orientation and upstream sequences. The genetic diversity of expressed var genes in relation to severity of disease in Tanzanian children was analysed. Methods Children with defined severe (SM) and asymptomatic malaria (AM) were recruited. Full-length var mRNA was isolated and reversed transcribed into var cDNA. Subsequently, the DBL and N-terminal domains, and up-stream sequences were PCR amplified, cloned and sequenced. Sequences derived from SM and AM isolates were compared and analysed. Results The analysis confirmed that the var family is highly diverse in natural Plasmodium falciparum populations. Sequence diversity of amplified var DBL-1? and upstream regions showed minimal overlap among isolates, implying that the var gene repertoire is vast and most probably indefinite in endemic areas. var DBL-1? sequences from AM isolates were more diverse with more singletons found (p<0.05) than those from SM infections. Furthermore, few var DBL-1? sequences from SM patients were rare and restricted suggesting that certain PfEMP1 variants might induce severe disease. Conclusions The genetic sequence diversity of var genes of P. falciparum isolates from Tanzanian children is large and its relationship to disease severity has been studied. Observed differences suggest that different var genes might have fundamentally different roles in the host-parasite interaction. Further research is required to examine clear disease-associations of var gene subsets in different geographical settings. The importance of very strict clinical definitions and appropriate large control groups needs to be emphasized for future studies on disease associations of PfEMP1.

2012-01-01

435

Identification of Novel Candidate Tumor Suppressor Genes Using C. elegans as a Model.  

National Technical Information Service (NTIS)

Molecular genetic analysis of the model organism Caenorhabditis elegans was used to identify and study mechanisms of action of negative regulators of tyrosine kinase/RAS mediated signal transduction that are candidate tumor suppressors. A homolog of the p...

P. W. Sternberg

1999-01-01

436

Widespread Protein Aggregation as an Inherent Part of Aging in C. elegans  

Microsoft Academic Search

Several hundred proteins become insoluble and aggregation-prone as a consequence of aging in Caenorhabditis elegans. The data indicate that these proteins influence disease-related protein aggregation and toxicity.

Della C. David; Noah Ollikainen; Jonathan C. Trinidad; Michael P. Cary; Alma L. Burlingame; Cynthia Kenyon

2010-01-01

437

Novel functions of lipid-binding protein 5 in Caenorhabditis elegans fat metabolism.  

PubMed

The lipid-binding protein (LBP) family is conserved from Caenorhabditis elegans to mammals and essential for fatty acid homeostasis. RNAi-mediated knockdown of nine C. elegans lbp family members revealed that lbp-5 regulates fat accumulation. C. elegans LBP-5 bound directly to various fatty acids with varying affinities. lbp-5 expression in nhr-49(nr2041) worms was much lower than in N2 worms. Nhr-49 transcriptional activity also decreased with lbp-5 deletion, suggesting that they may work together as functional partners in fat metabolism. In support of this notion, LBP-5 translocated into nuclei, where it appeared to influence C. elegans NHR-49 target genes involved in energy metabolism. Interestingly, LBP-5 is required for stearic acid-induced transcription of NHR-49 target genes. Thus, this knowledge could help identify therapeutic targets to treat obesity and diseases associated with nematode-host interactions. PMID:21697096

Xu, Mo; Joo, Hyoe-Jin; Paik, Young-Ki

2011-06-22

438

Something worth dyeing for: molecular tools for the dissection of lipid metabolism in Caenorhabditis elegans.  

PubMed

The nematode Caenorhabditis elegans (C. elegans) has during the last decade emerged as an invaluable eukaryotic model organism to understand the metabolic and neuro-endocrine regulation of lipid accumulation. The fundamental pathways of food intake, digestion, metabolism, and signalling are evolutionary conserved between mammals and worms making C. elegans a genetically and metabolically extremely tractable model to decipher new regulatory mechanisms of lipid storage and to understand how nutritional and genetic perturbations can lead to obesity and other metabolic diseases. Besides providing an overview of the most important regulatory mechanisms of lipid accumulation in C. elegans, we also critically assess the current methodologies to monitor lipid storage and content as various methods differ in their applicability, consistency, and simplicity. PMID:20371247

Elle, Ida Coordt; Olsen, Louise Cathrine Braun; Pultz, Dennis; Rødkaer, Steven Vestergaard; Faergeman, Nils Joakim

2010-04-03

439

Monitoring the clearance of apoptotic and necrotic cells in the nematode Caenorhabditis elegans.  

PubMed

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

2013-01-01

440

piRNAs and siRNAs collaborate in Caenorhabditis elegans genome defense.  

PubMed

ABSTRACT: Caenorhabditis elegans piRNAs promote genome surveillance by triggering siRNA-mediated silencing of nonself DNA in competition with licensing programs that support endogenous gene expression. PMID:22818087

Billi, Allison C; Freeberg, Mallory A; Kim, John K

2012-07-20

441

Toxic effects of acetochlor on mortality, reproduction and growth of Caenorhabditis elegans and Pristionchus pacificus.  

PubMed

The effects of acetochlor on the mortality, growth and reproduction of two nematode species were assessed. The LC50 values for Caenorhabditis elegans and Pristionchus pacificus were 1,296 and 210.7 mg/L at 24 h, and 540.0 and 126.4 mg/L at 48 h exposure, respectively. In three succession generations, reproductive capacity was more sensitive in P. pacificus than in C. elegans. Moreover, the sublethal test endpoint of final length was more sensitive with P. pacificus. This study suggested that acetochlor had no long-term effects on C. elegans at lower concentrations. The higher concentrations of acetochlor (from 40 to 160 mg/L) revealed sublethal toxicity to the two tested species, with P. pacificus being more sensitive than C. elegans. PMID:23212891

Zhang, Jingnan; Liang, Wenju; Wu, Xia; Jiang, Siwei; Li, Qi

2012-12-05

442

Roles of MicroRNAs in the Caenorhabditis elegans Nervous System.  

PubMed

The first microRNA was discovered in Caenorhabditis elegans in 1993, and since then, thousands of microRNAs have been identified from almost all eukaryotic organisms examined. MicroRNAs function in many biological events such as cell fate determination, metabolism, apoptosis, and carcinogenesis. So far, more than 250 microRNAs have been identified in C. elegans; however, functions for most of these microRNAs are still unknown. A small number of C. elegans microRNAs are associated with known physiological roles such as developmental timing, cell differentiation, stress response, and longevity. In this review, we summarize known roles of microRNAs in neuronal differentiation and function of C. elegans, and discuss interesting perspectives for future studies. PMID:24053946

Meng, Lingfeng; Chen, Liang; Li, Zhaoyong; Wu, Zheng-Xing; Shan, Ge

2013-08-07

443

RNA editing by ADARs is important for normal behavior in Caenorhabditis elegans  

PubMed Central

Here we take advantage of the well-characterized and simple nervous system of Caenorhabditis elegans to further our understanding of the functions of RNA editing. We describe the two C.elegans ADAR genes, adr-1 and adr-2, and characterize strains containing homozygous deletions in each, or both, of these genes. We find that adr-1 is expressed in most, if not all, cells of the C.elegans nervous system and also in the developing vulva. Using chemotaxis assays, we show that both ADARs are important for normal behavior. Biochemical, molecular and phenotypic analyses indicate that ADR-1 and ADR-2 have distinct roles in C.elegans, but sometimes act together.

Tonkin, Leath A.; Saccomanno, Lisa; Morse, Daniel P.; Brodigan, Thomas; Krause, Michael; Bass, Brenda L.

2002-01-01

444

Invasive cutaneous infection caused by Apophysomyces elegans associated with a spider bite.  

PubMed

Cutaneous infections by Zygomycetes may have underestimated clinical consequences. Apophysomyces elegans is a Zygomycete that rarely causes disease in humans. However, it has been reported with increasing frequency in warm climate zones as a result of infection in healthy patients after injury to the cutaneous barrier. The following case report describes a 30-year-old woman with deep tissue involvement of A. elegans associated with a spider bite and a fatal outcome. PMID:19389070

Saravia-Flores, Marcos; Guaran, Dennya M; Argueta, Victor

2009-03-07

445

The regulation of feeding and metabolism in response to food deprivation in Caenorhabditis elegans  

Microsoft Academic Search

This review considers the factors involved in the regulation of feeding and metabolism in response to food deprivation using\\u000a Caenorhabditis elegans as a model organism. Some of the sensory neurons and interneurons involved in food intake are described, together with an\\u000a overview of pharyngeal pumping. A number of chemical transmitters control feeding in C. elegans including 5-hydroxytryptamine (5-HT, serotonin), acetylcholine,

Sarah Luedtke; Vincent O’Connor; Lindy Holden-Dye; Robert J. Walker

2010-01-01

446

Identification of ciliary and ciliopathy genes in Caenorhabditis elegans through comparative genomics  

Microsoft Academic Search

Background  The recent availability of genome sequences of multiple related Caenorhabditis species has made it possible to identify, using comparative genomics, similarly transcribed genes in Caenorhabditis elegans and its sister species. Taking this approach, we have identified numerous novel ciliary genes in C. elegans, some of which may be orthologs of unidentified human ciliopathy genes.\\u000a \\u000a \\u000a \\u000a \\u000a Results  By screening for genes possessing canonical

Nansheng Chen; Allan Mah; Oliver E Blacque; Jeffrey Chu; Kiran Phgora; Mathieu W Bakhoum; C Rebecca Hunt Newbury; Jaswinder Khattra; Susanna Chan; Anne Go; Evgeni Efimenko; Robert Johnsen; Prasad Phirke; Peter Swoboda; Marco Marra; Donald G Moerman; Michel R Leroux; David L Baillie; Lincoln D Stein

2007-01-01

447

Dietary manipulation implicates lipid signaling in the regulation of germ cell maintenance in C. elegans  

Microsoft Academic Search

Reproduction in C. elegans relies on continuously proliferating germ cells which, during germline development, exit mitosis, undergo meiosis and differentiate into gametes. Supplementing the diet of C. elegans with dihommogamma-linolenic acid (20:3n-6, DGLA), a long chain omega-6 polyunsaturated fatty acid, results in sterile worms that lack germ cells. The effect is remarkably specific for DGLA, as eicosapentaenoic acid (20:5n-3, EPA)

Jennifer L. Watts; John Browse

2006-01-01

448

Salmonella typhimurium proliferates and establishes a persistent infection in the intestine of Caenorhabditis elegans.  

PubMed

Genetic analysis of host-pathogen interactions has been hampered by the lack of genetically tractable models of such interactions. We showed previously that the human opportunistic pathogen Pseudomonas aeruginosa kills Caenorhabditis elegans, that P. aeruginosa and C. elegans genes can be identified that affect this killing, and that most of these P. aeruginosa genes are also important for mammalian pathogenesis. Here, we show that Salmonella typhimurium as well as other Salmonella enterica serovars including S. enteritidis and S. dublin can also kill C. elegans. When C. elegans is placed on a lawn of S. typhimurium, the bacteria accumulate in the lumen of the worm intestine and the nematodes die over the course of several days. This killing requires contact with live bacterial cells. The worms die with similar kinetics when placed on a lawn of S. typhimurium for a relatively short time (3-5 hours) before transfer to a lawn of E. coli. After the transfer to E. coli, a high titer of S. typhimurium persists in the C. elegans intestinal lumen for the rest of the worms' life. Furthermore, feeding for 5 hours on a 1:1000 mixture of S. typhimurium and E. coli followed by transfer to 100% E. coli, also led to death after several days. This killing correlated with an increase in the titer of S. typhimurium in the C. elegans lumen, which reached 10,000 bacteria per worm. These data indicate that, in contrast to P. aeruginosa, a small inoculum of S. typhimurium can proliferate in the C. elegans intestine and establish a persistent infection. S. typhimurium mutated in the PhoP/PhoQ signal transduction system caused significantly less killing of C. elegans. PMID:11114525

Aballay, A; Yorgey, P; Ausubel, F M

2000-11-30

449

Ethanol sensitizes the nervous system of Caenorhabditis elegans nematode to heat stress.  

PubMed

Ethanol sensitizes the nervous system of C. elegans to heat stress, which manifested in exacerbation of locomotion disturbances induced by exposure to constant temperature 36°C. Adaptation of C. elegans to high temperature by heat shock (1 h at 32°C and 1 h at 18°C) or two-hour exposure at 30°C resulted considerably reduced sensitivity of the nervous system to the negative effects of ethanol under conditions of heat stress. PMID:21161051

Gainutdinov, M Kh; Timoshenko, A Kh; Petrov, A M; Gainutdinov, T M; Kalinnikova, T B

2010-12-01

450

KSAYMRFamide (PF3\\/AF8) Is Present in the Free-Living Nematode, Caenorhabditis elegans  

Microsoft Academic Search

To date, seven FMRFamide-related peptides (FaRPs) have been structurally characterized fromC. elegans,of which one is structurally identical to the parasitic nematode peptide AF2 (KHEYLRFamide). The other six FaRPs have so far been identified in free-living forms only. In the present study an additional FaRP was isolated and structurally characterized from an ethanolic extract ofC. elegans.The extract was screened using a

N. J. Marks; A. G. Maule; T. G. Geary; D. P. Thompson; C. Li; D. W. Halton; C. Shaw

1998-01-01

451

Using C. elegans to screen for targets of ethanol and behavior-altering drugs  

Microsoft Academic Search

Caenorhabditis elegans is an attractive model system for determining the targets of neuroactive compounds. Genetic screens in C. elegans provide a relatively unbiased approach to the identification of genes that are essential for behavioral effects of drugs\\u000a and neuroactive compounds such as alcohol. Much work in vertebrate systems has identified multiple potential targets of ethanol\\u000a but which, if any, of

Andrew G. Davies; Steven L. McIntire

2004-01-01

452

Ethanol Sensitizes the Nervous System of Caenorhabditis elegans Nematode to Heat Stress  

Microsoft Academic Search

Ethanol sensitizes the nervous system of C. elegans to heat stress, which manifested in exacerbation of locomotion disturbances induced by exposure to constant temperature 36°C.\\u000a Adaptation of C. elegans to high temperature by heat shock (1 h at 32oC and 1 h at 18°C) or two-hour exposure at 30°C resulted considerably reduced\\u000a sensitivity of the nervous system to the negative

M. Kh. Gainutdinov; A. Kh. Timoshenko; A. M. Petrov; T. M. Gainutdinov; T. B. Kalinnikova

2010-01-01

453

Caenorhabditis elegans as a model system to study aging of learning and memory  

Microsoft Academic Search

The nematode Caenorhabditis elegans is an excellent model organism to study biological processes relevant to a wide variety of human and rodent disease systems.\\u000a Previous studies have suggested that mutants of the insulin\\/insulin-like growth factor-1 pathway show life extension and increased\\u000a stress resistance in various species, including C. elegans, the fruit fly, and the mouse. It has recently been shown

Shin Murakami

2007-01-01

454

Effects of resveratrol on lifespan in Drosophila melanogaster and Caenorhabditis elegans  

Microsoft Academic Search

It was recently reported that the plant polyphenol resveratrol, found, e.g., in grape berry skins, extended lifespan in the fruit fly Drosophila melanogaster and the nematode worm Caenorhabditis elegans. This lifespan extension was dependent on an NAD+-dependent histone deacetylase, Sir2 in Drosophila and SIR-2.1 in C. elegans. The extension of lifespan appeared to occur through a mechanism related to dietary

Timothy M. Bass; David Weinkove; Koen Houthoofd; David Gems; Linda Partridge

2007-01-01

455

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

456

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

457

Caenorhabditis elegans as a model to study renal development and disease: sexy cilia.  

PubMed

The nematode Caenorhabditis elegans has no kidney per se, yet "the worm" has proved to be an excellent model to study renal-related issues, including tubulogenesis of the excretory canal, membrane transport and ion channel function, and human genetic diseases including autosomal dominant polycystic kidney disease (ADPKD). The goal of this review is to explain how C. elegans has provided insight into cilia development, cilia function, and human cystic kidney diseases. PMID:15647338

Barr, Maureen M

2005-01-12

458

Characterization of taurine as anti-obesity agent in C. elegans  

Microsoft Academic Search

BACKGROUND: Taurine plays an important role in reducing physiological stress. Recent studies indicated that taurine may serve as an anti-obesity agent at the cellular level. This study characterizes taurine’s potential anti-obesity function in C. elegans, which have become a popular in vivo model for understanding the regulatory basis of lipid biosynthesis and deposition. METHODS: Two strains of C. elegans were

Hye Min Kim; Chang-Hee Do; Dong Hee Lee

2010-01-01

459

Daf-2 Signaling Modifies Mutant SOD1 Toxicity in C. elegans  

Microsoft Academic Search

The DAF-2 Insulin\\/IGF-1 signaling (IIS) pathway is a strong modifier of Caenorhabditis elegans longevity and healthspan. As aging is the greatest risk factor for developing neurodegenerative diseases such as Amyotrophic Lateral Sclerosis (ALS), we were interested in determining if DAF-2 signaling modifies disease pathology in mutant superoxide dismutase 1 (SOD1) expressing C. elegans. Worms with pan-neuronal G85R SOD1 expression demonstrate

Marco Boccitto; Todd Lamitina; Robert G. Kalb

2012-01-01

460

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

461

Transgenic C. elegans Dauer Larvae Expressing Hookworm Phospho Null DAF-16\\/FoxO Exit Dauer  

Microsoft Academic Search

Parasitic hookworms and the free-living model nematode Caenorhabtidis elegans share a developmental arrested stage, called the dauer stage in C. elegans and the infective third-stage larva (L3) in hookworms. One of the key transcription factors that regulate entrance to and exit from developmental arrest is the forkhead transcription factor DAF-16\\/FoxO. During the dauer stage, DAF-16 is activated and localized in

Verena Gelmedin; Thomas Brodigan; Xin Gao; Michael Krause; Zhu Wang; John M. Hawdon; Vincent Laudet

2011-01-01

462

Multi-environment model estimation for motility analysis of Caenorhabditis Elegans  

Microsoft Academic Search

The nematode Caenorhabditis elegans is a well-known model organism used to\\u000ainvestigate fundamental questions in biology. Motility assays of this small\\u000aroundworm are designed to study the relationships between genes and behavior.\\u000aCommonly, motility analysis is used to classify nematode movements and\\u000acharacterize them quantitatively. Over the past years, C. elegans' motility has\\u000abeen studied across a wide range of

Raphael Sznitman; Manaswi Gupta; Gregory D. Hager; Paulo E. Arratia; Josué Sznitman; Vladimir Brezina

2010-01-01

463

A new transmembrane 4 superfamily molecule in the nematode, Caenorhabditis elegans  

Microsoft Academic Search

Transmembrane 4 superfamily (TM4SF) molecules are predominantly mammalian cell surface glycoproteins that are thought to transduce\\u000a signals mediating cell development, activation, and motility. Analysis of the Genpept sequence database reveals YKK8, a novel\\u000a member of the TM4SF in the nematode,Caenorhabditis elegans. YKK8 is a putative 27.4-kDa protein encoded by a gene on chromosome III of theC. elegans genome (Wilson et

Michael G. Tomlinson; Mark D. Wright

1996-01-01

464

Caenorhabditis elegans N-glycan Core ?-galactoside Confers Sensitivity towards Nematotoxic Fungal Galectin CGL2  

Microsoft Academic Search

The physiological role of fungal galectins has remained elusive. Here, we show that feeding of a mushroom galectin, Coprinopsis cinerea CGL2, to Caenorhabditis elegans inhibited development and reproduction and ultimately resulted in killing of this nematode. The lack of toxicity of a carbohydrate-binding defective CGL2 variant and the resistance of a C. elegans mutant defective in GDP-fucose biosynthesis suggested that

Alex Butschi; Alexander Titz; Martin A. Wälti; Vincent Olieric; Katharina Paschinger; Katharina Nöbauer; Xiaoqiang Guo; Peter H. Seeberger; Iain B. H. Wilson; Markus Aebi; Michael O. Hengartner; Markus Künzler

2010-01-01

465

Hydrogen Peroxide-Mediated Killing of Caenorhabditis elegans by Streptococcus pyogenes  

Microsoft Academic Search

Caenorhabditis elegans is currently introduced as a new, facile, and cheap model organism to study the pathogenesis of gram-negative bacteria such as Pseudomonas aeruginosa and Salmonella enterica serovar Ty- phimurium. The mechanisms of killing involve either diffusible exotoxins or infection-like processes. Recently, it was shown that also some gram-positive bacteria kill C. elegans, although the precise mechanisms of killing remained

W. T. M. Jansen; M. Bolm; R. Balling; G. S. Chhatwal; R. Schnabel

2002-01-01

466

A Rapid Respiratory Toxicity Test Using Caenorhabditis elegans with an Oxygen Electrode System  

Microsoft Academic Search

We describe a novel approach to evaluating the respiratory toxicity of chemicals in the free-living nematode Caenorhabditis elegans. Using DOX-96KT, a general purpose, multi-channel dissolved oxygen (DO) measuring system, we measured the DO concen- tration in culture media containing C. elegans exposed to chemicals to assay for respiratory toxicity. The cur- rent value, which is an index of the dissolved

Shinya Kohra; Nobuaki Tominaga; Yuji Takao; Masaki Nagae; Yasuhiro Ishibashi; Kazuo Ueda; Koji Arizonod

2002-01-01

467

Development and application of bioluminescent Caenorhabditis elegans as multicellular eukaryotic biosensors  

Microsoft Academic Search

We describe a novel approach to assess toxicity to the free-living nematode Caenorhabditis elegans that relies on the ability of firefly luciferase to report on endogenous ATP levels. We have constructed bioluminescent C. elegans with the luc gene under control of a constitutive promoter. Light reduction was observed in response to increasing temperature, concentrations of copper, lead and 3,5-dichlorophenol. This

C. Lagido; J. Pettitt; A. J. R. Porter; G. I. Paton; L. A. Glover

2001-01-01

468

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

469

Homologous and unique G protein alpha subunits in the nematode Caenorhabditis elegans.  

PubMed Central

A cDNA corresponding to a known G protein alpha subunit, the alpha subunit of Go (Go alpha), was isolated and sequenced. The predicted amino acid sequence of C. elegans Go alpha is 80-87% identical to other Go alpha sequences. An mRNA that hybridizes to the C. elegans Go alpha cDNA can be detected on Northern blots. A C. elegans protein that crossreacts with antibovine Go alpha antibody can be detected on immunoblots. A cosmid clone containing the C. elegans Go alpha gene (goa-1) was isolated and mapped to chromosome I. The genomic fragments of three other C. elegans G protein alpha subunit genes (gpa-1, gpa-2, and gpa-3) have been isolated using the polymerase chain reaction. The corresponding cosmid clones were isolated and mapped to disperse locations on chromosome V. The sequences of two of the genes, gpa-1 and gpa-3, were determined. The predicted amino acid sequences of gpa-1 and gpa-3 are only 48% identical to each other. Therefore, they are likely to have distinct functions. In addition they are not homologous enough to G protein alpha subunits in other organisms to be classified. Thus C. elegans has G proteins that are identifiable homologues of mammalian G proteins as well as G proteins that appear to be unique to C. elegans. Study of identifiable G proteins in C. elegans may result in a further understanding of their function in other organisms, whereas study of the novel G proteins may provide an understanding of unique aspects of nematode physiology. Images

Lochrie, M A; Mendel, J E; Sternberg, P W; Simon, M I

1991-01-01

470

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

471

Killing of Caenorhabditis elegans by Pseudomonas aeruginosa Used to Model Mammalian Bacterial Pathogenesis  

Microsoft Academic Search

We show that a single clinical isolate of the human opportunistic pathogen Pseudomonas aeruginosa (strain PA14), which previously was shown to be pathogenic in mice and plants, also kills Caenorhabditis elegans. The rate of PA14-mediated killing of C. elegans depends on the composition of the agar medium on which PA14 is grown. When PA14 is grown on minimal medium, killing

Man-Wah Tan; Shalina Mahajan-Miklos; Frederick M. Ausubel

1999-01-01

472

Impact of Cigarette Smoke Exposure on Innate Immunity: A Caenorhabditis elegans Model  

Microsoft Academic Search

BackgroundCigarette smoking is the major cause of chronic obstructive pulmonary disease (COPD) and lung cancer. Respiratory bacterial infections have been shown to be involved in the development of COPD along with impaired airway innate immunity.Methodology\\/Principal FindingsTo address the in vivo impact of cigarette smoke (CS) exclusively on host innate defense mechanisms, we took advantage of Caenorhabditis elegans (C. elegans), which

Rebecca M. Green; Fabienne Gally; Jonathon G. Keeney; Scott Alper; Bifeng Gao; Min Han; Richard J. Martin; Andrew R. Weinberger; Stephanie R. Case; Maisha N. Minor; Hong Wei Chu; Carol Feghali-Bostwick

2009-01-01

473

Caenorhabditis elegans Protein Arginine Methyltransferase PRMT-5 Negatively Regulates DNA Damage-Induced Apoptosis  

Microsoft Academic Search

Arginine methylation of histone and non-histone proteins is involved in transcription regulation and many other cellular processes. Nevertheless, whether such protein modification plays a regulatory role during apoptosis remains largely unknown. Here we report that the Caenorhabditis elegans homolog of mammalian type II arginine methyltransferase PRMT5 negatively regulates DNA damage-induced apoptosis. We show that inactivation of C. elegans prmt-5 leads

Mei Yang; Jianwei Sun; Xiaojuan Sun; Qinfang Shen; Zhiyang Gao; Chonglin Yang

2009-01-01

474

Candida albicans hyphal formation and virulence assessed using a Caenorhabditis elegans infection model.  

PubMed

Candida albicans colonizes the human gastrointestinal tract and can cause life-threatening systemic infection in susceptible hosts. We study here C. albicans virulence determinants using the nematode Caenorhabditis elegans in a pathogenesis system that models candidiasis. The yeast form of C. albicans is ingested into the C. elegans digestive tract. In liquid media, the yeast cells then undergo morphological change to form hyphae, which results in aggressive tissue destruction and death of the nematode. Several lines of evidence demonstrate that hyphal formation is critical for C. albicans pathogenesis in C. elegans. First, two yeast species unable to form hyphae (Debaryomyces hansenii and Candida lusitaniae) were less virulent than C. albicans in the C. elegans assay. Second, three C. albicans mutant strains compromised in their ability to form hyphae (efg1Delta/efg1Delta, flo8Delta/flo8Delta, and cph1Delta/cph1Delta efg1Delta/efg1Delta) were dramatically attenuated for virulence. Third, the conditional tet-NRG1 strain, which enables the external manipulation of morphogenesis in vivo, was more virulent toward C. elegans when the assay was conducted under conditions that permit hyphal growth. Finally, we demonstrate the utility of the C. elegans assay in a screen for C. albicans virulence determinants, which identified several genes important for both hyphal formation in vivo and the killing of C. elegans, including the recently described CAS5 and ADA2 genes. These studies in a C. elegans-C. albicans infection model provide insights into the virulence mechanisms of an important human pathogen. PMID:19666778

Pukkila-Worley, Read; Peleg, Anton Y; Tampakakis, Emmanouil; Mylonakis, Eleftherios

2009-08-07

475

Multiple sensory G proteins in the olfactory, gustatory and nociceptive neurons modulate longevity in Caenorhabditis elegans  

Microsoft Academic Search

The life span of the nematode Caenorhabditis elegans is under control of sensory signals detected by the amphid neurons. In these neurons, C. elegans expresses at least 13 G? subunits and a G? subunit, which are involved in the transduction and modulation of sensory signals. Here, we show that loss-of-function mutations in the G? subunits odr-3, gpa-1 and gpa-9, in the

Hannes Lans; Gert Jansen

2007-01-01