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Caenorhabditis elegans

…a species of free-living nematode worm that boasts a cosmopolitan distribution. C.elegans are mostly found in rotting fruit and moist soil and adults will feed on a variety of bacteria. C.elegans eggs are laid by a hermaphroditic adult after hatching they will go four stages (L1-L4) where they will develop. It takes about 14 hours to complete these stages and sperm/oocytes are produced in the L4 stage. If the nematode is crowded or in the absence of feed it will enter a dauer stage, in the dauer stage the larvae will become stress-resistant and will not age.

C.elegans is a common sight in laboratories as it is used as a model organism for animal development. C.elegans was even the first multicellular organism to have its genome sequenced.

Phylogeny

Animalia-Nematoda-Chormadorea-Rhabditida-Rhabditidae-Caenorhabditis-C.elegans

Image(s) Bob Goldstein

The worm that feels at home in space

Caenorhabditis elegans is a transparent nematode worm about 1 mm in length. It lives in temperate soil but research shows that it adapts very well to space conditions.

Astronauts return to Earth weakened and unsteady after weightlessness and radiation in space take their toll on the human body. New research now shows that the humble nematode worm adapts much better to spaceflight.

When ESA astronaut André Kuipers first went to space in 2004 to the International Space Station he took with him some microscopic Caenorhabditis elegans worms.

An international team of scientists from the US, Japan, France and Canada were interested in seeing how C. elegans reacts to living in space.

This species was chosen because it was the first multicellular life form to have its full genetic structure mapped.

Afterwards, researchers found the astronaut worms showed less toxic proteins in their muscles than if they had stayed on Earth, according to results published in the journal Nature Scientific Reportsrecently.

Credits: ESA

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Tardigrades (Water Bears/Moss Piglets): 

These ambling, eight-legged microscopic “bears of the moss” are cute, ubiquitous, all but indestructible and a model organism for education

by William R. Miller

The young woman in my office doorway is inquiring about the summer internship I am offering. What’s a tardigrade? she asks…

Tardigrades, I reply, are microscopic, aquatic animals found just about everywhere on Earth. Terrestrial species live in the interior dampness of moss, lichen, leaf litter and soil; other species are found in fresh or salt water.

They are commonly known as water bears, a name derived from their resemblance to eight-legged pandas. Some call them moss piglets and they have also been compared to pygmy rhinoceroses and armadillos. On seeing them, most people say tardigrades are the cutest invertebrate.

At one time water bears were candidates to be the main model organism for studies of development. That role is now held most prominently by the roundworm Caenorhabditis elegans, the object of study for the many distinguished researchers following in the trail opened by Nobel Prize laureate Sydney Brenner, who began working on C. elegans in 1974. Water bears offer the same virtues that have made C. elegans so valuable for developmental studies: physiological simplicity, a fast breeding cycle and a precise, highly patterned development plan…

(read more: American Scientist)

images: Eye of Science/Photo Researchers and Dr. David J. Patterson/Photo Researchers. Illustration at bottom by Tom Dunne, adapted from a figure by the author.

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DUELING NEMATODES

Dramatic scenes are played out under evolutionary biologist Ralf Sommer’s microscope: his research object, the roundworm Pristionchus pacificus, bites another worm, tears open a hole in its side and devours the oozing contents.

Pristionchus pacificus was developed as a model organism by biologists at the Max Planck Institute for Developmental Biology in Tübingen.  Read about P. pacificus  at WormBook [an online review of nematode biology].

The squirming victim does not stand a chance in this duel: Caenorhabditis elegans may be a close relative of Pristionchus; unfortunately, however, it does not have the same strong “teeth”.

Gilberto Bento and Akira Ogawa from Sommer’s team have discovered the control mechanism that lies behind the development of the organism’s mouth:

  • if the worm grows up with an abundant supply of bacteria as its source of nutrition, it only develops very small teeth and a narrow oral cavity.
  • If it experiences a lack of food or a high population density at the larval stage, it develops a wide mouth equipped with strong teeth-like denticles.

______________________________________________

Pristionchus’ mouth dimorphism demonstrates two fascinating evolutionary principles simultaneously,” says Ralf Sommer:

  1. First, it shows how frugally evolution works: signalling pathways that have already been established are re-used in a new context – biologists refer to this process as co-option. In order to assign a new significance to a signalling chain, all that needs to be done is to activate it at a different time or with a different concentration of the signalling molecule that triggers its activation, as occurs in this case.
  2. Moreover, the existence of alternative body structures is viewed as paving the way for evolution: “In order to change the mouth structure permanently, the genetic control would only have to be decoupled from the environmental dependency,” explains Ralf Sommer. 

(Based on the Max Planck Institute’s A worm bites off enough to chew, by Susanne Diederich.)

Using precisely-targeted lasers, researchers manipulate neurons in worms’ brains and take control of their behavior

In the quest to understand how the brain turns sensory input into behavior, Harvard scientists have crossed a major threshold. Using precisely-targeted lasers, researchers have been able to take over an animal’s brain, instruct it to turn in any direction they choose, and even to implant false sensory information, fooling the animal into thinking food was nearby.

As described in a September 23 paper published in Nature, a team made up of Sharad Ramanathan, an Assistant Professor of Molecular and Cellular Biology, and of Applied Physics, Askin Kocabas, a Post-Doctoral Fellow in Molecular and Cellular Biology, Ching-Han Shen, a Research Assistant in Molecular and Cellular Biology, and Zengcai V. Guo, from the Howard Hughes Medical Institute were able to take control of Caenorhabditis elegans – tiny, transparent worms – by manipulating neurons in the worms’ “brain.”

(Image credit: Ian D. Chin-Sang)

Como no solo con bacterias vie el biólogo, hoy tenemos a un ilustre invitado de la mas alta alcúrnia Caenorhabditis elegans, un nemátodo de lo mas elegante, siempre viste de Microbio y luccino, hace su aparición en la microtira, pocas veces tenemos alguien de la clase alta, ¡Disfrutadlo!

Agradecimientos: A Javi por la idea, aunque no sepas que es hacer el canario, te queremos igual

How Worms, Flies and Humans are Related

Gendron Recheche, #Cancer

The genetic machinery of humans, fruit flies and roundworms is similar in many surprising ways, biologists have said. This is a discovery that could help basic research into disease. A consortium of more than 200 scientists compared the genome of modern man with that of two creatures widely studied in the lab — the fruitfly (Drosophila melanogaster) and a tiny creature called roundworm (Caenorhabditis elegans). Even though the three species are obviously …

http://dlvr.it/6lJKTD
Comparative analysis of metazoan chromatin organization

Genome function is dynamically regulated in part by chromatin which consists of the histones nonhistone proteins and #RNA molecules that package DNA. Studies in Caenorhabditis elegans and Drosophila melanogaster have contributed substantially to our underst… http://bit.ly/1tZ9U2p #bioportfolio

Worms, flies and humans: how we are related

Biologists on Wednesday said the genetic machinery of humans, fruit flies and roundworms was similar in many surprising ways, a discovery that could help basic research into disease. A consortium of more than 200 scientists compared the genome of modern man with that of two creatures widely studied in the lab — the fruitfly (Drosophila melanogaster) and a tiny creature called roundworm (Caenorhabditis elegans). “When we look at flies or worms, it is difficult to believe that humans have anything in common with them,” said Mark Gerstein, a professor of biomedical informatics at Yale University. http://q.gs/7ZoPi
OrthoClust: an orthology-based network framework for clustering data across multiple species

Increasingly, high-dimensional genomics data are becoming available for many organisms.Here, we develop OrthoClust for simultaneously clustering data across multiple species. OrthoClust is a computational framework that integrates the co-association networks of individual species by utilizing the orthology relationships of genes between species. It outputs optimized modules that are fundamentally cross-species, which can either be conserved or species-specific. We demonstrate the application of OrthoClust using the #RNA-Seq expression profiles of Caenorhabditis elegans and Drosophila melanogaster from the modENCODE consortium. A potential application of cross-species modules is to infer putative analogous functions of uncharacterized elements like non-coding #RNAs based on guilt-by-association. http://bit.ly/1pKEZYg #BMC

Comparative analysis of metazoan chromatin organization

Genome function is dynamically regulated in part by chromatin, which consists of the histones, non-histone proteins and #RNA molecules that package DNA. Studies in Caenorhabditis elegans and Drosophila melanogaster have contributed substantially to our understanding of molecular mechanisms of genome function in humans, and have revealed conservation of chromatin components and mechanisms. Nevertheless, the three organisms have markedly different genome sizes, chromosome architecture and gene organization. On human and fly chromosomes, for example, pericentric heterochromatin flanks single centromeres, whereas worm chromosomes have dispersed heterochromatin-like regions enriched in the distal chromosomal ‘arms’, and centromeres distributed along their lengths. To systematically investigate chromatin organization and associated gene regulation across species, we generated and analysed a large collection of genome-wide chromatin data sets from cell lines and developmental stages in worm, fly and human. Here we present over 800 new data sets from our ENCODE and modENCODE consortia, bringing the total to over 1,400. Comparison of combinatorial patterns of histone modifications, nuclear lamina-associated domains, organization of large-scale topological domains, chromatin environment at promoters and enhancers, nucleosome positioning, and DNA replication patterns reveals many conserved features of chromatin organization among the three organisms. We also find notable differences in the composition and locations of repressive chromatin. These data sets and analyses provide a rich resource for comparative and species-specific investigations of chromatin composition, organization and function. http://bit.ly/1tVSmnQ #nature #npg

Crystal structure of a nematode-infecting virus [Biophysics and Computational Biology]

Orsay, the first virus discovered to naturally infect Caenorhabditis elegans or any nematode, has a bipartite, positive-sense #RNA genome. Sequence analyses show that Orsay is related to nodaviruses, but molecular characterizations of Orsay reveal several unique features, such as the expression of a capsid–δ fusion protein and the use of…

http://bit.ly/1p7i4Gn #PNAS
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