Unais' web

2011-05-11T22:44:00.000+05:30

A Complex Landscape of Genetic Interactions

2011-05-09T22:12:00.000+05:30

A skyscape of white dots picks out a circle on a black background. Connecting the dots are faint wispy trails of webbing, and among the white are galactic clusters of blue, red, lime, teal, yellow, pink, and other lurid colors. But this is no night sky. The labels, colored like the galaxies they refer to, give that away: "Mitochondria," "Nuclear-cytoplasmic transport," "DNA replication & repair."

This picture—which would take considerably more than a thousand words to explore fully—is the centerpiece of the paper at #6 and shows, as the paper’s title has it, "the genetic landscape of a cell.
Charles Boone, at the Donnelly Centre for Cellular and Biomolecular Research of the University of Toronto in Canada, and a large team compiled a detailed look at the interrelationships between thousands of genes of yeast (Saccharomyces cerevisiae) into a picture of the genetic landscape. What is both astonishing and humdrum about it is that the functional clusters picked out in color were not preselected. They emerged from what the authors call a "functionally unbiased genetic interaction map."
In a sense, that is to be expected. One might assume that genes that operate in concert as part of a complex function would interact more often than genes not linked in this way. The surprise is how clearly this shows up in the landscape map.
Yeast has about 6,000 genes. Boone and his group had systematically deleted single genes, and showed that very few—about 20%--are essential. The rest the organism can manage without, although it may take a fitness hit, reproducing more slowly than a normal yeast.
The team then turned its attention to double mutants; did they grow more or less slowly than one might expect based on the combined effect of the two mutations taken singly? A difference in the double mutant would indicate that the two genes interacted in some way. A pairwise screen of 1,712 genes, chosen at random, yielded about 5.4 million comparisons, among which were 170,000 significant interactions between pairs of genes.
Most were negative, where the absence of two genes had an even greater effect than expected from the absence of either one alone. Genes that are part of the same biological process tend to share similar genetic interactions, and this was the key to building the network of the landscape.
Each node on the network is a gene, its distance from other genes based on the similarity between its pattern of interactions and the overall pattern. Genes of known function clearly clustered together. Indeed, the team used the clusters to pin functions on previously uncharacteristic genes.
Taking a broader perspective, most of the genes had very few interactions, while a small number were highly connected as network hubs. Among the hubs, there were some that were much more likely to have negative interactions than positive, and a smaller number that were more likely to be positive than negative.
The two sets were functionally distinct. Negative interactions were common among genes responsible for the cell’s normal progress through the cycle of growth and cell division. This analysis thus confirms the notion of a series of checkpoints that keep cells healthy by blocking progress if anything is going wrong. Positive interactions were found among genes responsible for DNA translation and the processing of RNA which, the team says, "may suggest that defects in the translation machinery somehow mask phenotypes that would otherwise be expressed in normal cells."
Network hubs were interesting in other ways, too. There is a clear link between the degree to which a gene is connected and its impact on fitness as a single mutant. The more severe the fitness defect, the greater the number of positive and negative interactions. Hubs also exhibited pleiotropy; that is, they were connected to a greater number of distinct functional groups.
Looking across 23 different fungi related to yeast, network hub genes were more highly conserved than other genes. Zooming in, interactions among genes sometimes revealed bridges between different processes. Genes involved in secretion and vesicle transport were among the most highly connected, emphasizing their role as channels of communication.
These are just a few of the highlights from the paper, which is as rich as the landscape it pictures. The progress from studying the effect of single-gene mutations, to two-gene interactions, to the full constellation of interactions that defines the genetic landscape has confirmed in entirely new ways that cellular processes are highly organized and well buffered against disturbance.
Further advances are promised, for example in drug discovery and a deeper understanding of the complex routes from genotype to phenotype. One can only imagine the insights that will emerge from comparing the genetic landscapes of different organisms.

The Islamic Online University (IOU)

2011-05-09T21:52:00.001+05:30

The Islamic Online University (IOU) is the brainchild of Dr. Bilal Philips. He envisioned an institution that would offer online intensive, undergraduate, and graduate courses in Islamic Studies completely tuition-free.

Dr. Bilal Philips, Founder and Dean, Islamic Online University

The IOU was launched in 2007 from Qatar with an offering of completely free diploma courses.

Alhamdulillah, although we began with 1,500 students in 2007, by the end of 2008, the number of registered students tripled, reaching 4,500. And now, as 2010 draws to a close, Allah has blessed the IOU with a student body of over 30,000 students from over 177 different countries.

In 2010 the IOU launched the world's first tuition-free, online Bachelor of Arts in Islamic Studies. This path-breaking initiative utilizes the worldwide presence of the Internet and advanced open source online learning technology to bring low-cost, university level Islamic education within reach of anyone on the planet who has access to a computer and the Internet.

Thus the IOU Now has two separate virtual campuses: the degree campus and the diploma campus. Each campus is hosted on its own dedicated server.

For more details http://www.islamiconlineuniversity.com/about-us.php

National Sceince Award

2010-10-23T00:02:00.000+05:30

Alhamdhulillah

NSF web

Click on the globe above to see the list of award winners for popularizing science among school students. Awarded by National Science Foundation.

Fwd: HEART ATTACKS & WATER

2010-10-20T19:00:00.001+05:30

Heart attack an Cold water

This is not only about the warm water after your meal, but about Heart Attacks. The Chinese and Japanese drink hot tea with their meals, not cold water, maybe it is time we adopt their drinking habit while eating.

For those who like to drink cold water, this article is applicable to you.
It is nice to have a cup of cold drink after a meal.
However, the cold water will solidify the oily stuff that you have just consumed.
It will slow down the digestion.
Once this 'sludge' reacts with the acid, it will break down and be absorbed by the intestine faster than the solid food.
It will line the intestine..
Very soon, this will turn into fats and lead to cancer & arthritis .
It is best to drink hot soup or warm water after a meal.

Common Symptoms Of Heart Attack...

A serious note about heart attacks - You should know that not every heart attack symptom is going to be the left arm hurting .

Be aware of intense pain in the jaw line .

You may never have the first chest pain during the course of a heart attack.

Nausea and intense sweating are also common symptoms.

60% of people who have a heart attack while they are asleep do not wake up.

Pain in the jaw can wake you from a sound sleep.

Let's be careful and be aware.

The more we know, the better chance we could survive.

A cardiologist says if everyone who reads this message sends it to 10 people, you can be sure that we'll save at least one life.

Ciculatory System

2010-05-20T12:30:00.000+05:30