 |
|
Evolution of genomic imprinting
September 07, 2007How we come to express the genes of one parent over the other is now better understood through studying the platypus and marsupial wallaby - and it doesn't seem to have originated in association with sex chromosomes. New research published in the online open access journal, BMC Evolutionary Biology, has shed light on the evolution of genomic imprinting, in which specific genes on chromosomes that have been inherited from one parent are expressed in an organism, while the same genes on the chromosome inherited from the other parent are repressed.
Imprinting arises from some kind of 'epigenetic memory' - modifications to the DNA from one parent, such as the way the chromosomal material is packaged, that do not allow particular genes to be expressed. The reasons why imprinting evolved are not understood. It is known, however, that different patterns of imprinting occur in different classes of mammals, with some classes of mammals exhibiting the phenomenon and others not. Because the evolutionary relationship between mammals is well documented, patterns of imprinting in the different genomes can provide important clues about the evolution of imprinting.
One theory is that imprinted genes arose from sex chromosomes, which can be epigenetically 'shut down' to control the dosage of genes. Another idea is that imprinting arose from an ancestral chromosome that was itself imprinted.
A group led by father and daughter, Malcolm and Anne Ferguson-Smith, of the University of Cambridge tested these ideas by mapping known sequences of imprinted genes in two mammals, the monotreme platypus and the marsupial wallaby, which occupy distinct positions in mammalian evolution.
The results of the distribution studies suggest that imprinted genes were not located on an ancestrally imprinted chromosome, nor were they associated with sex chromosomes. Rather it appears that imprinting evolved in a stepwise, adaptive way, with each gene or cluster becoming imprinted as the need arose.
The study is also important because despite its evolutionary importance, the platypus remains cytogenetically under-characterised. By linking specific sequences to particular chromosomes, the researchers have pinpointed important markers on the platypus genome.
BioMed Central
A group led by father and daughter, Malcolm and Anne Ferguson-Smith, of the University of Cambridge tested these ideas by mapping known sequences of imprinted genes in two mammals, the monotreme platypus and the marsupial wallaby, which occupy distinct positions in mammalian evolution.
The results of the distribution studies suggest that imprinted genes were not located on an ancestrally imprinted chromosome, nor were they associated with sex chromosomes. Rather it appears that imprinting evolved in a stepwise, adaptive way, with each gene or cluster becoming imprinted as the need arose.
The study is also important because despite its evolutionary importance, the platypus remains cytogenetically under-characterised. By linking specific sequences to particular chromosomes, the researchers have pinpointed important markers on the platypus genome.
BioMed Central
Chromosomes Current Events and Chromosomes News RSSScientists at UA, collaborating institutions decode maize genome
Scientists from the University of Arizona led by Arizona Genomics Institute director Rod A. Wing and from collaborating institutions have deciphered the complete genetic code of the maize plant for the first time.
New map of variation in maize genetics holds promise for developing new varieties
A new study of maize has identified thousands of diverse genes in genetically inaccessible portions of the genome. New techniques may allow breeders and researchers to use this genetic variation to identify desirable traits and create new varieties that were not easily possible before.
New Maize Map to Aid Plant Breeding Efforts
In a massive survey of genetic diversity in maize, also known as corn, researchers across the United States, have developed a gene map that should pave the way to significant improvements in a plant that is a major source of food, fuel, animal feed and fiber around the world.
Chromosomes dance and pair up on the nuclear membrane
Meiosis - the pairing and recombination of chromosomes, followed by segregation of half to each egg or sperm cell - is a major crossroads in all organisms reproducing sexually.
Largest gene study of childhood IBD identifies 5 new genes
In the largest, most comprehensive genetic analysis of childhood-onset inflammatory bowel disease (IBD), an international research team has identified five new gene regions, including one involved in a biological pathway that helps drive the painful inflammation of the digestive tract that characterizes the disease.
NIH-funded researchers transform embryonic stem cells into human germ cells
Researchers funded in part by the National Institutes of Health have discovered how to transform human embryonic stem cells into germ cells, the embryonic cells that ultimately give rise to sperm and eggs.
A solution to Darwin's 'mystery of the mysteries' emerges from the dark matter of the genome
Biological species are often defined on the basis of reproductive isolation. Ever since Darwin pointed out his difficulty in explaining why crosses between two species often yield sterile or inviable progeny (for instance, mules emerging from a cross between a horse and a donkey), biologists have struggled with this question.
Common weed could provide clues on aging and cancer
A common weed and human cancer cells could provide some very uncommon details about DNA structure and its relationship with telomeres and how they affect cellular aging and cancer, according to a team led by scientists from Texas A&M University and the University of Cincinnati (UC).
CSHL-led team discovers rare mutation dramatically increasing schizophrenia risk
An international team of researchers led by geneticist Jonathan Sebat, Ph.D., of Cold Spring Harbor Laboratory (CSHL), has identified a mutation on human chromosome 16 that substantially increases risk for schizophrenia.
Standards for a new genomic era
A team of geneticists at Los Alamos National Laboratory, together with a consortium of international researchers, has recently proposed a set of standards designed to elucidate the quality of publicly available genetic sequencing information.
More Chromosomes Current Events and Chromosomes News Articles
 |
Chromosome 6 by Robin Cook (Author) In his most prophetic novel, Robin Cook challenges the ethics of genetic manipulation and cloning. "Shocking and thought-provoking...Cook's best to date." (ssociated Press) |
 |
The Calcutta Chromosome: A Novel of Fevers, Delirium & Discovery by Amitav Ghosh (Author) From Victorian lndia to near-future New York, The Calcutta Chromosome takes readers on a wondrous journey through time as a computer programmer trapped in a mind-numbing job hits upon a curious item that will forever change his life. When Antar discovers the battered I.D. card of a long-lost acquaintance, he is suddenly drawn into a spellbinding adventure across centuries and around the globe, into the strange life of L. Murugan, a man obsessed with the medical history of malaria, and into a magnificently complex world where conspiracy hangs in the air like mosquitoes on a summer night. |
 |
Chromosome Abnormalities and Genetic Counseling (Oxford Monographs on Medical Genetics, No. 46) by R. J. McKinlay Gardner (Author), Grant R. Sutherland (Author) Genetic Health Services Victoria and Murdoch Children's Institute, Melbourne, Australia. Discusses genetic counseling and how to help concerned parents make informed decisions. Covers the basics of genetics, parents with chromosomal abnormality, and prenatal diagnosis. Previous edition: c1996. |
 |
Neon Genesis Evangelion: Sequel to Angel Chromosome-XX Series 1: Arael-XX Figure by Yamato Neon Genesis Evangelion: Sequel to Angel Chromosome-XX Series 1: Arael-XX Figure. The Angel's may be gone, but the threat remains. In their latest diabolical plan, NERVE recklessly intends to cross human DNA with that of the Angels. The plan: Project-XX. The results: Angel Chromosome-XX. WAVE in collaboration with GAINAX and Kannon Yoshizaki continues to bring this next chapter in the Evangelion saga to figural life with A-15 Arael-XX. Joining previous experiments A-03 Sachiel-XX, A-14 Zeruel-XX, A-17 Tabris-XX, and A-02 Lilith-XX, Arael-XX measures approximately 5.15" and is depicted impaled with the Lance of Longinus which brought about her demise. |
 |
The X in Sex: How the X Chromosome Controls Our Lives by David Bainbridge (Author) "A tiny scrap of genetic information determines our sex; it also consigns many of us to a life of disease, directs or disrupts the everyday working of our bodies, and forces women to live as genetic chimeras. The culprit--so necessary and yet the source of such upheaval--is the X chromosome, and this is its story. An enlightening and entertaining tour of the cultural and natural history of this intriguing member of the genome, The X in Sex traces the journey toward our current understanding of the nature of X. From its chance discovery in the nineteenth century to the promise and implications of ongoing research, David Bainbridge shows how the X evolved and where it and its counterpart Y are going, how it helps assign developing human babies their sex--and maybe even their sexuality--and... |
 |
His & Hers Chromosome Towels - XX by T.R. Miller Co., Inc. Geeks understand the importance of towels. And sometimes two geeks get together and live in the same house. Know what that leads to? Towel fights. Not the sort where you wet one end and snap it, but fights over whose towel is whose. First, we thought we'd solve that the same way nations do. But it's impractical to stick flags in towels. They never stay upright, and then the nylon gets all wet, and it's just a bad scene all around. So we went with the monogram option. Choose your towel by the applicable set of sex chromosomes. And voila! No more towel confusion. We're afraid if you live in a single sex dorm, this isn't going to help. Unless you're the only science-y one there. And then, score! |
 |
As An Ex-Anorexic's Six Sick Ex It A Faulty Chromosome (Primary Contributor) |
 |
Chromosomes & Genes Starring: Sunburst Visual Media Directed By: Sunburst Visual Media Modern society is being bombarded with new information about genetics every day! Make sure your students understand the key concepts that will enable them to fully understand this topic. Students are intrigued that genes can influence looks and behavior! |
 |
Chromosome Gun by Ultralyd |
|
Chromosomes & Genes (Teacher's Video Company) |
| © 2009 BrightSurf.com |