Shopping on line can be easy, simple and save you lots of money. It can also take a lot of your time, frustrate you, and result in unwanted purchases. Now the same can be said for regular high street shopping, but with the vast opportunity presented by the Internet it will pay you to spend a few minutes reading this and understanding how to better optimize your Caenorhabditis Elegans shopping experience:

1. Compare - without doubt the biggest advantage that the Caenorhabditis Elegans offers shoppers today is the ability to compare thousands of Caenorhabditis Elegans at a time. This is a great thing, but not necessarily all the time! Too much can be daunting at times so take advantage of the great comparison sites and where possible let them do the hard work for you.

2. Research - if it has been said it will be on the internet. Ignorance is no longer a justifiable reason for buying the wrong thing. Take the time to research in detail everything that you could possible want to know about

3. Testimonials - don't know anybody that has bought a Caenorhabditis Elegans? Wrong! If the Caenorhabditis Elegans is good the internet will let you know. Use the Internet as a friend and get testimonials before you buy.

4. Questions - Got a question about Caenorhabditis Elegans then search the Forums, FAQ's, Blogs etc. Don't be afraid to ask .....

5. Reputation - Never heard of the company selling Caenorhabditis Elegans? Don't worry, no reason why you should know every company in the world, but you know someone that does! Use the internet to find out what people are saying about Caenorhabditis Elegans and build up a picture of their reputation for sales, returns, customer service, delivery etc.

6. Returns - still worried that even after all of the above your Caenorhabditis Elegans wont be what you want? Check out the returns policy. There is so much competition now that someone, somewhere is bound to offer the terms that you are comfortable with.

7. Feedback - happy with your Caenorhabditis Elegans then let people know, after all you are depending on others people input in your buying decision, so why not give a little back.

8. Security - check for the yellow padlock on the Caenorhabditis Elegans site before you buy, and the s after http:/ /i.e. https:// = a secure site

9. Contact - got a question about Caenorhabditis Elegans, or want to leave a comment then check out the sites contact page. Reputable companies have them and respond.

10. Payment - ready to pay for your Caenorhabditis Elegans, then use your credit card or PayPal! Be aware of companies that don't accept them, there may be genuine reasons but given the huge amount of choice you have when buying online there is no reason at all not to buy via credit card or PayPal.

{{Taxobox| color = pink| name = Caenorhabditis elegans| image = Adult Caenorhabditis elegans.jpg| image_width = 300px| image_caption = An adult hermaphrodite C. elegans worm| regnum = Animalia]| classis = Secernentea| familia = [Rhabditidae| species = elegans| binomial = Caenorhabditis elegans| binomial_authority = [Émile Maupas, 1900-->

Caenorhabditis elegans (International Phonetic Alphabet: ) is a free-living nematode (roundworm), about 1 Millimetre in length, which lives in temperate soil environments. Research into the molecular biology and developmental biology of C. elegans was begun in 1974 by Sydney Brenner  and it has since been used extensively as a model organism.

Biology C. elegans is unsegmented, vermiform, symmetry (biology)#Bilateral symmetry, with a cuticle integument, four main epidermal cords and a fluid-filled pseudocoelomate cavity. Members of the species have many of the same organ systems as other animals. In the wild, they feed on bacteria that develop on decaying vegetable matter. C. elegans has both a hermaphrodite sex, and a very rare male population, which makes up 0.05% of the total C. elegans on average. The basic anatomy of C. elegans includes a mouth, pharynx, intestine, gonad, and collagenous cuticle. Males have a single-lobed gonad, vas deferens, and a tail specialized for mating. Hermaphrodites have two ovaries, oviducts, spermatheca, and a single uterus.

C. elegans eggs are laid by the hermaphrodite. After hatching, they pass through four larval stages (L1-L4). When crowded or in the absence of food, C. elegans can enter an alternative third larval stage called the dauer larva state. Dauer larvae are stress-resistant and do not age. Hermaphrodites produce all their sperm in the L4 stage (150 sperm per gonadal arm) and then switch over to producing oocytes. The sperm are stored in the same area of the gonad as the oocytes until the first oocyte pushes the sperm into the spermatheca (a kind of chamber where the oocytes become fertilized by the sperm).  . The male can inseminate the hermaphrodite, which will use male sperm preferentially (both types of sperm are stored in the spermatheca). When self-inseminated the wild-type worm will lay approximately 300 eggs. When inseminated by a male, the number of progeny can exceed 1,000. At 20Celsius, the laboratory strain of C. elegans has an average life span of approximately 2–3 weeks and a generation time of approximately 4 days. Hermaphrodites can mate with males or self-fertilize.

C. elegans has five pairs of autosomes and one pair of sex chromosomes. Sex in C. elegans is based on an X0 sex-determination system. Hermaphrodite C. elegans have a matched pair of sex chromosomes (XX); the rare males have only one sex chromosome (X0).

Laboratory uses C. elegans is studied as a model organism for a variety of reasons. Strain (biology) are cheap to breed and can be frozen. When subsequently thawed they remain viable, allowing long-term storage. Because the complete cell lineage of the species has been determined, C. elegans has proven especially useful for studying cellular differentiation.

From a research perspective, C. elegans has the advantage of being a multicellular Eukaryote organism which is simple enough to be studied in great detail. The developmental fate of every single somatic cell (959 in the adult hermaphrodite; 1031 in the adult male) has been mapped out. These patterns of cell lineage are largely invariant between individuals, in contrast to mammals where cell development from the embryo is more largely dependent on cellular cues. In both sexes, a large number of additional cells (131 in the hermaphrodite, most of which would otherwise become neurons), are eliminated by programmed cell death (apoptosis).



In addition, C. elegans is one of the simplest organisms with a nervous system. In the hermaphrodite, this comprises 302 neurons whose pattern of connectivity has been completely mapped out, and shown to be a small-world network . Research has explored the neural mechanisms responsible for several of the more interesting behaviors shown by C. elegans, including chemotaxis, thermotaxis, mechanotransduction, and male mating behavior. Interestingly, the neurons fire no action potentials.

A useful feature of C. elegans is that it is relatively straightforward to disrupt the function of specific genes by RNA interference (RNAi). Gene silencing the function a gene in this way can sometimes allow a researcher to infer what the function of that gene may be. The nematode can either be soaked in (or injected with) a solution of double stranded RNA, the sequence of which is complentary to the sequence of the gene that the researcher wishes to disable. Alternatively, worms can be fed on genetically transformed bacteria which gene expression the double stranded RNA of interest.

C. elegans has also been useful in the study of meiosis. As sperm and egg nuclei move down the length of the gonad, they undergo a temporal progression through meiotic events. This progression means that every nuclei at a given position in the gonad will be at roughly the same step in meiosis, eliminating the difficulties of heterogeneous populations of cells.

The organism has also been identified as a model for nicotine dependence as it has been found to experience the same symptoms humans experience when they Smoking cessation. 

As for most model organisms, there is a dedicated online database for the species that is actively curated by scientists working in this field. The Wormbase database attempts to collate all published information on C. elegans and other related nematodes. A reward of $5000 has been advertised on their website, for the finder of a new species of closely related nematode.{{cite web|title=Caenorhabditis isolation guide|url=http://wormbase.org/external/2007/nematode_isolation_guide/nematode_isolation_guide.html|publisher=WormBase|accessdate=2007-08-30--> Such a discovery would broaden research opportunities with the worm.

The genome C. elegans was the first multicellular organism to have its genome completely sequencing. The finished genome sequence was published in 1998, although a number of small gaps were present (the last gap was finished by October 2002). The C. elegans genome sequence is approximately 100 million base pairs long and contains approximately 20,000 genes. The vast majority of these genes encode for proteins but there are likely to be as many as 1,000 RNA genes. Scientific curators continue to appraise the set of known genes, such that new gene predictions continue to be added and incorrect ones modified or removed.

In 2003, the genome sequence of the related nematode Caenorhabditis briggsae was also determined, allowing researchers to study the comparative genomics of these two organisms . Work is now ongoing to determine the genome sequences of more nematodes from the same genus such as C. remanei , C. japonica and C. brenneri . These newer genome sequences are being determined by using the whole genome shotgun technique which means that the resulting genome sequences are likely to not be as complete or accurate as C. elegans (which was sequenced using the 'hierarchical' or clone (genetics)-by-clone appoach).

The official version of the C. elegans genome sequence continues to change as and when new evidence reveals errors in the original sequencing (DNA sequencing is not an error free process). Most changes are usually minor, adding or removing only a few base pairs (bp) of DNA.E.g. the WS169 release of WormBase (December 2006) lists a net gain of 6 bp to the genome sequence . Occasionally more extensive changes are made, e.g. the WS159 release of May 2006 added over 300 bp to the sequence .

Nematode evolution It has been shown that a small number of conserved protein sequences from sea sponge are more similar to humans than to C. elegans . This suggests that there has been an accelerated rate of evolution in the ''C. elegans'' [Lineage (evolution). The same study found that several [phylogenetically ancient genes are not present in ''C. elegans''.

C. elegans scientists In 2002, the Nobel Prize in Physiology or Medicine was awarded to Sydney Brenner, H. Robert Horvitz and John Sulston for their work on the genetics of organ development and apoptosis (PCD) in C. elegans. The 2006 Nobel Prize in Physiology or Medicine was awarded to Andrew Fire and Craig C. Mello, for their discovery of RNA interference in C. elegans.A. Fire, S.Q. Xu, M.K. Montgomery, S.A. Kostas, S. E. Driver, C.C. Mello: Potent and specific genetic interference by double-stranded RNA in Caenorhabditis elegans. In: Nature. 391/1998, S. 806-811,

Because all research into C. elegans essentially started with Sydney Brenner in the 1970's, many scientists working in this field share a close connection to Brenner (they either worked as a post-doctoral or post-graduate researcher in Brenner's lab or in the lab of someone who previously worked with Brenner). Because most people who worked in his lab went on to establish their own worm research labs, there is now a fairly well documented 'lineage' of C. elegans scientists. This lineage was recorded in some detail at the 2003 International Worm Meeting and the results were stored in the Wormbase database.

C. elegans in the media C. elegans made news when it was discovered that specimens had survived the Space Shuttle Columbia disaster in February 2003.

See also

References

Relevant publications







Online resources

Nobel lectures

External links

{{Taxobox| color = pink| name = Caenorhabditis elegans| image = Adult Caenorhabditis elegans.jpg| image_width = 300px| image_caption = An adult hermaphrodite C. elegans worm| regnum = Animalia]| classis = Secernentea| familia = [Rhabditidae| species = elegans| binomial = Caenorhabditis elegans| binomial_authority = [Émile Maupas, 1900-->

Caenorhabditis elegans (International Phonetic Alphabet: ) is a free-living nematode (roundworm), about 1 Millimetre in length, which lives in temperate soil environments. Research into the molecular biology and developmental biology of C. elegans was begun in 1974 by Sydney Brenner  and it has since been used extensively as a model organism.

Biology C. elegans is unsegmented, vermiform, symmetry (biology)#Bilateral symmetry, with a cuticle integument, four main epidermal cords and a fluid-filled pseudocoelomate cavity. Members of the species have many of the same organ systems as other animals. In the wild, they feed on bacteria that develop on decaying vegetable matter. C. elegans has both a hermaphrodite sex, and a very rare male population, which makes up 0.05% of the total C. elegans on average. The basic anatomy of C. elegans includes a mouth, pharynx, intestine, gonad, and collagenous cuticle. Males have a single-lobed gonad, vas deferens, and a tail specialized for mating. Hermaphrodites have two ovaries, oviducts, spermatheca, and a single uterus.

C. elegans eggs are laid by the hermaphrodite. After hatching, they pass through four larval stages (L1-L4). When crowded or in the absence of food, C. elegans can enter an alternative third larval stage called the dauer larva state. Dauer larvae are stress-resistant and do not age. Hermaphrodites produce all their sperm in the L4 stage (150 sperm per gonadal arm) and then switch over to producing oocytes. The sperm are stored in the same area of the gonad as the oocytes until the first oocyte pushes the sperm into the spermatheca (a kind of chamber where the oocytes become fertilized by the sperm).  . The male can inseminate the hermaphrodite, which will use male sperm preferentially (both types of sperm are stored in the spermatheca). When self-inseminated the wild-type worm will lay approximately 300 eggs. When inseminated by a male, the number of progeny can exceed 1,000. At 20Celsius, the laboratory strain of C. elegans has an average life span of approximately 2–3 weeks and a generation time of approximately 4 days. Hermaphrodites can mate with males or self-fertilize.

C. elegans has five pairs of autosomes and one pair of sex chromosomes. Sex in C. elegans is based on an X0 sex-determination system. Hermaphrodite C. elegans have a matched pair of sex chromosomes (XX); the rare males have only one sex chromosome (X0).

Laboratory uses C. elegans is studied as a model organism for a variety of reasons. Strain (biology) are cheap to breed and can be frozen. When subsequently thawed they remain viable, allowing long-term storage. Because the complete cell lineage of the species has been determined, C. elegans has proven especially useful for studying cellular differentiation.

From a research perspective, C. elegans has the advantage of being a multicellular Eukaryote organism which is simple enough to be studied in great detail. The developmental fate of every single somatic cell (959 in the adult hermaphrodite; 1031 in the adult male) has been mapped out. These patterns of cell lineage are largely invariant between individuals, in contrast to mammals where cell development from the embryo is more largely dependent on cellular cues. In both sexes, a large number of additional cells (131 in the hermaphrodite, most of which would otherwise become neurons), are eliminated by programmed cell death (apoptosis).



In addition, C. elegans is one of the simplest organisms with a nervous system. In the hermaphrodite, this comprises 302 neurons whose pattern of connectivity has been completely mapped out, and shown to be a small-world network . Research has explored the neural mechanisms responsible for several of the more interesting behaviors shown by C. elegans, including chemotaxis, thermotaxis, mechanotransduction, and male mating behavior. Interestingly, the neurons fire no action potentials.

A useful feature of C. elegans is that it is relatively straightforward to disrupt the function of specific genes by RNA interference (RNAi). Gene silencing the function a gene in this way can sometimes allow a researcher to infer what the function of that gene may be. The nematode can either be soaked in (or injected with) a solution of double stranded RNA, the sequence of which is complentary to the sequence of the gene that the researcher wishes to disable. Alternatively, worms can be fed on genetically transformed bacteria which gene expression the double stranded RNA of interest.

C. elegans has also been useful in the study of meiosis. As sperm and egg nuclei move down the length of the gonad, they undergo a temporal progression through meiotic events. This progression means that every nuclei at a given position in the gonad will be at roughly the same step in meiosis, eliminating the difficulties of heterogeneous populations of cells.

The organism has also been identified as a model for nicotine dependence as it has been found to experience the same symptoms humans experience when they Smoking cessation. 

As for most model organisms, there is a dedicated online database for the species that is actively curated by scientists working in this field. The Wormbase database attempts to collate all published information on C. elegans and other related nematodes. A reward of $5000 has been advertised on their website, for the finder of a new species of closely related nematode.{{cite web|title=Caenorhabditis isolation guide|url=http://wormbase.org/external/2007/nematode_isolation_guide/nematode_isolation_guide.html|publisher=WormBase|accessdate=2007-08-30--> Such a discovery would broaden research opportunities with the worm.

The genome C. elegans was the first multicellular organism to have its genome completely sequencing. The finished genome sequence was published in 1998, although a number of small gaps were present (the last gap was finished by October 2002). The C. elegans genome sequence is approximately 100 million base pairs long and contains approximately 20,000 genes. The vast majority of these genes encode for proteins but there are likely to be as many as 1,000 RNA genes. Scientific curators continue to appraise the set of known genes, such that new gene predictions continue to be added and incorrect ones modified or removed.

In 2003, the genome sequence of the related nematode Caenorhabditis briggsae was also determined, allowing researchers to study the comparative genomics of these two organisms . Work is now ongoing to determine the genome sequences of more nematodes from the same genus such as C. remanei , C. japonica and C. brenneri . These newer genome sequences are being determined by using the whole genome shotgun technique which means that the resulting genome sequences are likely to not be as complete or accurate as C. elegans (which was sequenced using the 'hierarchical' or clone (genetics)-by-clone appoach).

The official version of the C. elegans genome sequence continues to change as and when new evidence reveals errors in the original sequencing (DNA sequencing is not an error free process). Most changes are usually minor, adding or removing only a few base pairs (bp) of DNA.E.g. the WS169 release of WormBase (December 2006) lists a net gain of 6 bp to the genome sequence . Occasionally more extensive changes are made, e.g. the WS159 release of May 2006 added over 300 bp to the sequence .

Nematode evolution It has been shown that a small number of conserved protein sequences from sea sponge are more similar to humans than to C. elegans . This suggests that there has been an accelerated rate of evolution in the ''C. elegans'' [Lineage (evolution). The same study found that several [phylogenetically ancient genes are not present in ''C. elegans''.

C. elegans scientists In 2002, the Nobel Prize in Physiology or Medicine was awarded to Sydney Brenner, H. Robert Horvitz and John Sulston for their work on the genetics of organ development and apoptosis (PCD) in C. elegans. The 2006 Nobel Prize in Physiology or Medicine was awarded to Andrew Fire and Craig C. Mello, for their discovery of RNA interference in C. elegans.A. Fire, S.Q. Xu, M.K. Montgomery, S.A. Kostas, S. E. Driver, C.C. Mello: Potent and specific genetic interference by double-stranded RNA in Caenorhabditis elegans. In: Nature. 391/1998, S. 806-811,

Because all research into C. elegans essentially started with Sydney Brenner in the 1970's, many scientists working in this field share a close connection to Brenner (they either worked as a post-doctoral or post-graduate researcher in Brenner's lab or in the lab of someone who previously worked with Brenner). Because most people who worked in his lab went on to establish their own worm research labs, there is now a fairly well documented 'lineage' of C. elegans scientists. This lineage was recorded in some detail at the 2003 International Worm Meeting and the results were stored in the Wormbase database.

C. elegans in the media C. elegans made news when it was discovered that specimens had survived the Space Shuttle Columbia disaster in February 2003.

See also

References

Relevant publications







Online resources

Nobel lectures

External links



Caenorhabditis elegans - Wikipedia, the free encyclopedia
Caenorhabditis elegans (pronounced /ˌsiːnoʊræbˈdaɪt ɪ s ˈɛl ɪ gænz/) is a free-living nematode (roundworm), about 1  mm in length, which lives in temperate soil ...

Caenorhabditis elegans WWW Server
Offers genome data, features an introduction to the field, a list of worm labs, literature, meeting announcements and software.

Caenorhabditis elegans Genetics and Genomics
Leon Avery (leon@eatworms.swmed.edu) Last modified: Thu Dec 2 11:32:58 2004

Welcome to PIR [Protein Information Resource]
Produces a non-redundant annotated protein sequence database. PIR features integrated annotation search to support functional/structural genomics and proteomic research.

C. elegans Project
The C. elegans sequencing project is a collaboration between the Sanger Institute, Hinxton Hall, Cambridge and the Genome Sequencing Center at the Washington University School of ...

Caenorhabditis elegans: Introduction
a C. elegans adult hermaphrodite . An introduction to the nematode Caenorhabditis elegans. Mark Blaxter, Institute of Evolutionary Biology, University of Edinburgh, UK

Caenorhabditis elegans in Edinburgh
Caenorhabditis elegans. Caenorhabditis elegans is a small, freeliving nematode that is the subject of an extensive integrated analysis of the genetics of development.

Parasitology: proteome maps
d: Caenorhabditis elegans run on a 4-7 pH IPG gradient. The full image is 13K. d: Fasciola hepatica (whole) run on a 3-10 pH IPG gradient.

Caenorhabditis elegans - Wikispecies
This page was last modified on 17 February 2007, at 02:18. Content is available under GNU Free Documentation License. Privacy policy; About Wikispecies; Disclaimers

Caenorhabditis elegans WWW Server
Caenorhabditis elegans is a small (about 1 mm long) soil nematode found in temperate regions. In the 1960's Sydney Brenner began using it to study the genetics of development and ...

 

Caenorhabditis Elegans



 
Copyright © 2008 Hintcenter.com - All rights reserved.
Home | Terms of Use | Privacy Policy
All Trademarks belong to their repective owners. Many aspects of this page are used under
commercial commons license from Yahoo!