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Lakartidningen,
2002]
Recently the complete genomic sequences for three very different multicellular organisms have been published, from one nematode (Caenorhabditis elegans), one fly (Drosophila melanogaster) and human (Homo sapiens). Of course, this means a breakthrough in many ways for biological research. Summarised in this article are the findings made using these genomic sequences regarding the protein family of nuclear receptors. This is a group of transcription factors involved in many important biological processes, i.e. regulation of cholesterol homeostasis and fertility; classical members of this protein family are, amongst others, the receptors for estradiol and progesterone.
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Trends Pharmacol Sci,
2001]
Complete nucleotide sequences are now available for different species of the animal kingdom: Caenorhabditis elegans - a nematode, Drosophila - an insect, and humans - a mammal. Such information makes it possible to compare the set of nuclear receptors found in these organisms, and to discuss the possible reasons for the differences observed. The human genome sequencing identified few new receptors, which implies that most nuclear receptors have now been found. However, information about polymorphisms and regulating sequences, obtained through genomic sequencing, will be important for understanding receptor function and disease mechanisms. The surprisingly large number of nuclear receptors in C. elegans might have implications for the development of pharmaceuticals and the understanding of the function of these animals. By contrast, Drosophila has few nuclear receptors; however, examination of the unique nuclear receptors provides information about the function of these receptors.
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Trends Pharmacol Sci,
2000]
Nuclear receptors represent a large class of ligand-activated transcriptional regulators; about 70 members of this protein family have been cloned from mammalian or insect species. Thus, it came as a great surprise when the recent completion of the Caenorhabditis elegans genome revealed at least 228 genes for nuclear receptors. Clearly, some of these receptors are homologues of known receptors, but most lack homologues in other species. Whether these receptors possess homologues in mammalian species is of great interest; if these do exist, the size of the nuclear receptor superfamily could also expand dramatically in humans.
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Ageing Res Rev,
2013]
We have conducted a comprehensive literature review regarding the effect of vitamin E on lifespan in model organisms including single-cell organisms, rotifers, Caenorhabditis elegans, Drosophila melanogaster and laboratory rodents. We searched Pubmed and ISI Web of knowledge for studies up to 2011 using the terms "tocopherols", "tocotrienols", "lifespan" and "longevity" in the above mentioned model organisms. Twenty-four studies were included in the final analysis. While some studies suggest an increase in lifespan due to vitamin E, other studies did not observe any vitamin E-mediated changes in lifespan in model organisms. Furthermore there are several studies reporting a decrease in lifespan in response to vitamin E supplementation. Different outcomes between studies may be partly related to species-specific differences, differences in vitamin E concentrations and the vitamin E congeners administered. The findings of our literature review suggest that there is no consistent beneficial effect of vitamin E on lifespan in model organisms which is consistent with reports in human intervention studies.
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Hermann, Editeurs des Sciences et des Arts. Paris, France.,
2002]
L'espce Caenorhabditis elegans fut dcrite en 1900 Alger par E. Maupas, qui s'intressait son mode de reproduction hermaphrodite. Plus tard, vers le milieu du vingtime sicle, V. Nigon et ses collaboratuers Lyon tudirent les reorganizations cellulaires accompagnant la fecundation et les premiers clivages. J. Brun isola les preiers mutants morpholgiques.
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Parasite,
1994]
Two genes coding for cuticlin components of Coenorhabditis elegans have been cloned and their structure is described. Recombinant proteins have been produced in E. coli and antibodies raised against them. Nucleic acid and specific antibodies are being used to isolate the homologues from the parasitic species Ascaris lumbricoides and Brugia pahangi.
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Seminars in Developmental Biology,
1994]
Gastrulation in Caenorhabditis elegans has been described by following the movements of individual nuclei in living embryos by Nomarski microscopy. Gastrulation starts in the 26-cell stage when the two gut precursors, Ea and Ep, move into the blastocoele. The migration of Ea and Ep does not depend on interactions with specific neighboring cells and appears to rely on the earlier fate specification of the E lineage. In particular, the long cell cycle length of Ea and Ep appears important for gastrulation. Later in embryogenesis, the precursors to the germline, muscle and pharynx join the E descendants in the interior. As in other organisms, the movement of gastrulation permit novel cell contacts that are important for the specification of certain cell fates.
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Wiley Interdiscip Rev Dev Biol,
2013]
The transcriptional regulatory hierarchy that controls development of the Caenorhabditis elegans endoderm begins with the maternally provided SKN-1 transcription factor, which determines the fate of the EMS blastomere of the four-cell embryo. EMS divides to produce the posterior E blastomere (the clonal progenitor of the intestine) and the anterior MS blastomere, a major contributor to mesoderm. This segregation of lineage fates is controlled by an intercellular signal from the neighboring P2 blastomere and centers on the HMG protein POP-1. POP-1 would normally repress the endoderm program in both E and MS but two consequences of the P2-to-EMS signal are that POP-1 is exported from the E-cell nucleus and the remaining POP-1 is converted to an endoderm activator by complexing with SYS-1, a highly diverged -catenin. In the single E cell, a pair of genes encoding small redundant GATA-type transcription factors, END-1 and END-3, are transcribed under the combined control of SKN-1, the POP-1/SYS-1 complex, as well as the redundant pair of MED-1/2 GATA factors, themselves direct zygotic targets of SKN-1 in the EMS cell. With the expression of END-1/END-3, the endoderm is specified. END-1 and END-3 then activate transcription of a further set of GATA-type transcription factors that drive intestine differentiation and function. One of these factors, ELT-2, appears predominant; a second factor, ELT-7, is partially redundant with ELT-2. The mature intestine expresses several thousand genes, apparently all controlled, at least in part, by cis-acting GATA-type motifs.
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Curr Opin Chem Biol,
2014]
The site specific, co-translational introduction of unnatural amino acids into proteins produced in cells has been facilitated by the development of the pyrrolysyl-tRNA synthetase/tRNACUA pair. This pair can now be used to direct the site-specific incorporation of designer amino acids in E. coli, yeast, mammalian cells, and animals (the worm, C. elegans and the fly, D. melanogaster). Developments in encoding components of rapid bioorthogonal reactions are providing new opportunities for labelling and visualising proteins. A new method called stochastic orthogonal recoding of translation with chemoselective modification (SORT-M) leverages advances in genetic code expansion and bioorthogonal chemistry to label proteomes with diverse chemistry at diverse codons in E. coli, mammalian cells, and in spatially and temporally defined sets of cells in the fly. Proteomes in targeted sets of cells have been visualised by SORT-M and proteins in targeted cells have been identified by SORT-M.
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Mol Reprod Dev,
2015]
Developmental robustness is the ability of an embryo to develop normally despite many sources of variation, from differences in the environment to stochastic cell-to-cell differences in gene expression. The nematode Caenorhabditis elegans exhibits an additional level of robustness: Unlike most other animals, the embryonic pattern of cell divisions is nearly identical from animal to animal. The endoderm (gut) lineage is an ideal model for studying such robustness as the juvenile gut has a simple anatomy, consisting of 20 cells that are derived from a single cell, E, and the gene regulatory network that controls E specification shares features with developmental regulatory networks in many other systems, including genetic redundancy, parallel pathways, and feed-forward loops. Early studies were initially concerned with identifying the genes in the network, whereas recent work has focused on understanding how the endoderm produces a robust developmental output in the face of many sources of variation. Genetic control exists at three levels of endoderm development: Progenitor specification, cell divisions within the developing gut, and maintenance of gut differentiation. Recent findings show that specification genes regulate all three of these aspects of gut development, and that mutant embryos can experience a "partial" specification state in which some, but not all, E descendants adopt a gut fate. Ongoing studies using newer quantitative and genome-wide methods promise further insights into how developmental gene-regulatory networks buffer variation. Mol. Reprod. Dev. 2015. 2015 Wiley Periodicals, Inc.