Genetic Basis for Animal Tameness Identified

Genetic Basis for Animal Tameness Identified

Caitlin Judge

A team of European scientists from Germany, Sweden and Russia have identified genomic regions in the DNA of the common brown rat (Rattus norvegicus) that are responsible for the docility of the animals’ behaviour towards humans. In a study originating decades ago, a rat population captured in the wilderness around a major Russian city was separated into groups according to their aggression towards their captors- aggressive rats behaved violently whilst “friendly” rats were passive and compliant. These groups were breed within each other to ultimately create two populations displaying highly distinct reactions to humans (a tame and an aggressive group). The groups were then interbreed over several generations and their genomes studied. Over 45 traits were examined, including anxiety-related traits and organ weights. It was discovered that two loci, for anxiety-related traits and the weight of the rat’s adrenal gland were part of an epistatic network of loci influencing the rat’s tameness.


This study has significant implications. The discovery of these rat genes provides a foundation for further study of the genetic basis of animal tameness in other species, and may aid our ability to domestic species that so far have proved resistant to taming, such as the African Buffalo. Knowledge of the genetic basis of animal docility shall aid our understanding of what determines how animals interact with humans, and potentially each other, and may lead to breeding strategies that have the ability to promote human tolerance in animal generations.

LINKS
ScienceDaily 9th June 2009 ‘Genetic Region For Tame Animals Discovered: Horse Whisperers, Lion Tamers Not Needed’ retrieved June 9, 2009, from http://www.sciencedaily.com­ /releases/2009/06/090608131152.htm
To access the study as it appears in Genetic magazine:

Albert et al. Genetic Architecture of Tameness in a Rat Model of Animal Domestication. Genetics, 2009; 182 (2): 541 DOI: 10.1534/genetics.109.102186

Impact of environmental factor to the phenotype

Identical Twins Not So Identical

Identical twins are not quite as identical as once thought, according to a new study of DNA.

Life, it seems, changes everyone in unique ways.

One twin might get cancer while the the other is not susceptible, for example. Many identical twins clearly behave differently as they grow older, and some even grow to look less alike.

Such differences have to do not with the twins' identical DNA, which is the software of life, but in how genes express themselves, the research found. The differences stem from chemical modifications in the genes over the years.

These epigenetic effects, as they are called, are the result of chemical exposure, dietary habits and other environmental factors, the scientists believe.

The study is detailed in this week's Proceedings of the National Academy of Sciences.

Further investigation into the process might shed light on how cancers develop, said Ohio State University researcher Christoph Plass, a co-author of the report.

The idea that twins grow apart is not new.

In 2001, scientists documented that identical twins with different diets had corresponding differences in blood cholesterol measures. A study in 2002 found that identical twins tend to differ greatly in their levels of emotional distress, depending on how close each was to their mother or whether they attended church, among other social factors.

Research last year at Duke University found that identical twins both develop Alzheimer's by their late 70s only about 40 percent of the time. In many cases, one does and one does not.

Other studies have shown that the brains of identical twins look different upon close inspection of the wiring.

The new research, among the first to provide a detailed look at such differences at the genetic level, was led by Manel Esteller of the Spanish National Cancer Center in Madrid. The scientists studied 40 pairs of twins in Spain, Denmark and the United Kingdom, aged three through 74. The participants were surveyed on a range of health, exercise, eating habits and other lifestyle issues. Their blood was analyzed for epigenetic differences.

The youngest set of twins had the most identical genomes. Genetically, the oldest twins were the least alike.

Gene expression and behavior is altered by a process called methylation. Scientists think a better understanding of methylation could aid cancer research.

"One would expect identical twins to develop and express genes at the same levels, but in fact this changes over time," Plass said. "We think that methylation plays a genome-wide role in these changes."

Identical Twins Not So Identical

By Robert Roy Britt,LiveScience Senior Writer

Study reveals startling new role for the plant hormone auxin

A team of scientists from the University of California, Davis discovered something new about the hormone auxin in plants. They found that auxin acts as a morphogen which directs the pattern of cell development based on concentration.
Plants reproduction system is located within its flower, where pollens produce sperm cells while egg cells are in the ovule. During the development stage, the ovule will undergoes both meiosis and mitosis several times. This resulting in a structure of embryo sac together with the production of 8 nuclei and three of them are positioned near the opening of the ovule. Figure below shows the position of 8 nuclei in the embryo sac.

Caption: A gradient (red) in the concentration of the plant hormone auxin, determines that only one of the eight undifferentiated nuclei in a plant's embryo sac will become an egg. (In this image, a large vacuole dominates the central section of the embryo sac.)
Credit: Monica Alandete-Saez/UC Davis

The studies discovered that the only nuclei that receive most hormone auxin will continue to develop into egg cell and later to be fertilized with sperm cell. Based on their observation, the hormone auxin is concentrated nearer to the opening of the embryo sac. Thus, the nucleus that is nearer to the opening of ovule will become egg cell. The researchers had carried out a trial to test this hypothesis where they purposely shifted the position of one nucleus nearer to end of embryo sac of plant Arabidopsis. And the result was; instead of one, two egg cells were produced.
Furthermore, they found out that this hormone auxin is produced within the embryo sac itself. This discovery may help in enhancing the fertility of crop plants where greater number of eggs could be developed into mature plants.

This article was published on June 4, 2009.

Article links: http://www.genengnews.com/news/bnitem.aspx?name=55667708

By Zaira Hidayah Mohd Arshad 42102119

Menopause Timing Genes Found

May 26th 2009

Scientists have found up to 20 genetic variations that bring forward the menopause for a woman, a European conference was told. The variations were found in four different places on two chromosomes, 19 and 20.
The findings came from an analysis of the genes of more than 10,000 women in Britain, the USA, the Netherlands, Iceland and Italy. Researcher Lisette Stolk, from Erasmus MC, Rotterdam, Netherlands, said: "We know that ten years before menopause women are much less fertile, and five years before many are infertile.

"In Western countries, where women tend to have children later in life and closer to menopause, age at menopause can be an important factor in whether or not a particular woman is able to become a mother." A second study published last night warns that women approaching the menopause may suffer loss of learning ability.
In the journal Neurology, researchers say the problem surfaces during the period just before the menopause begins - but it is only temporary. The researchers say the problem might be treated by using hormone supplements. Researcher Dr Gail Greendale said: "The good news is that the effect of perimenopause on learning seems to be temporary. Our study found that the amount of learning improved back to premenopausal levels during the postmenopausal stage."

by: 42101327

http://www.staffnurse.com/nursing-news-articles/menopause-timing-genes-found-3556.html

Enzyme Necessary for DNA Synthesis Can Also Erase DNA

New mechanism that causes some changes in DNA content has been found by a group of Uppsala University scientists and it is due to something has happened in bacteria that live as a parasite inside the cells of other organisms.

Change in the amount of DNA in the chromosomes of bacteria can be either by gene amplification and gene deletion by which the amount is increasing and decreasing respectively.

Currently a genetic analysis on salmonella mutant done by a PhD student, Sanna Koskiniemi has shown that in order for spontaneous deletions are to take placed in the bacteria a special type DNA-synthesizing enzyme must be present. The decreased or increased rates of deletion up to 30 times are proven by genetically inactivating or overproducing these enzymes.
Professor Dan Andersson suggests that bacteria that live either as parasites inside cells or in symbiosis with other organisms are of special interest with regard to this new mechanism. As DNA has disappeared during evolution, thus, these bacteria often have small chromosomes. With these new findings we can better understand and predict how DNA is eliminated from chromosomes.

Link to the original article:
http://www.sciencedaily.com/releases/2009/06/090608182541.htm

By: 42111577