Aged people get more cancers than young ones due to use of Non-homologous end joining instead of homologous recombination for repairing double strand breaks

Double stranded breaks are the most dangerous form of DNA damage occurring in the genome. Double strand breaks are caused by internal agents like reactive oxygen species and many external agents like radiation.  Replication errors also cause double strand breaks.   Living organisms have two methods for correcting this error: Homologous recombination(HR) found both in bacteria and eukaryotes and non-homologous end joining (NHEJ) found mostly in eukaryotes. HR is a method which corrects the double strand breaks by using the homologous chromosome as the reference (this is the reason for diploid nature of most eukaryotes). Except for gene conversion, it does not cause mutation  to the genes in which the double strand break has occurred (usually broken ends have damaged bases which are removed  and correct bases are added by HR using the homologous chromosome as the template). But NHEJ just joins the broken ends without replacing the damaged bases (as it does not have a template to refer) leading to mutation of the genes in which double strand breaks occurred.

BREAKTHROUGH DISCOVERY: Neonatal genome sequencing for mutation detection

Non-invasive prenatal diagnostics analysis is desired for detection of  inherited mutations and common polymorphisms.  But, proper methods were not available  for doing this.   A new method has been discovered  by researchers from University of Washington (USA),  University of Bari (Italy),  Fred Hutchinson Cancer Research Center (USA), University of Washington School of Medicine (USA),  University of Iowa Hospitals and Clinics (USA), Seattle Children’s Research Institute (USA) and Howard Hughes Medical Institute (USA) combines   genome sequencing of two parents, genome-wide maternal haplotyping,

Segmental genome duplication responsible for our brain power

Genome duplication is the trigger for evolution. Complex multicellular organisms have evolved from simple unicellular organisms by genome duplication and other genome rearrangements. Genome duplication can be of two types: whole genome duplication in which a diploid organism becomes a tetraploid and provide whole set of additional genes i.e for every old gene a new copy is provided. This type of change is considered to be responsible for major changes in organisms including speciation. The second type of duplication is called segmental duplication or copy number variation.  Here only a part of the genome gets duplicated and provide additional copies of only those genes in the duplicated regions. This type of  variation is considered to be responsible for differences among closely related organisms for example between monkeys and humans. Immediately after sequencing genomes of chimp and other primates Scientists were expecting to find a segmental duplication of  genomic regions possessing genes associated with  the brain i.e neural system but were not successful.

Recently  two  groups of Scientists led by Evan Eichler and Franck Polleux have found a part of the missing clue.  They identified segmental duplication that led to

DNA sequencing found to be better than flow cytometry in predicting cancer relapse

In a recent study Scientists at  University of Washington, University of New Mexico Health Sciences Center, University of Virginia,  University of California and  Fred Hutchinson Cancer Research Center have found that  high-throughput sequencing could improve the diagnosis and post-treatment monitoring of leukemia. The sequencing-based method is more sensitive than flow cytometry and cheaper  and faster than the quantitative real-time PCR. They used high throughput sequencing (HTS)  to the diagnosis of T-lineage acute lymphoblastic leukemia/lymphoma. 43 paired patient samples were used for assessing

Two Human Ancestor Species Co-Existed

A fossil discovered in Ethiopia suggests that humans' prehistoric relatives may have lived in the trees for a million years longer than was previously thought.
The find may be our first glimpse of a separate, extinct, branch of the human family, collectively called hominins. It also hints that there may have been several evolutionary paths leading to feet adapted for walking upright.
The fossil, a partial foot, was found in 3.4-million-year-old rocks at Woranso-Mille in the Afar region of Ethiopia. Bones of the hominin Australopithecus afarensis — the species to which the famous 'Lucy' skeleton belongs — have also been found in this location and from the same period.

Au. afarensis has a big toe that is more closely aligned with the other digits on the foot, an adaptation that provides support during upright walking. Au. afarensis “was fully bipedal and had already abandoned life in the trees”, says study author Yohannes Haile-Selassie of the Cleveland Museum of Natural History in Ohio, whereas the newly discovered creature had not seemingly committed to life on the ground.But unlike Au. afarensis, the latest find has an opposable big toe — rather like a thumb
 on the foot — that would have allowed the species to grasp branches while climbing. Modern apes have similar toes, but the youngest hominin previously known to have them is Ardipithecus ramidus, which lived about 4.4 million years ago. The details of the discovery are published today in Nature1.
Other features of the fossil foot show that it did not belong to an ape, but that it is truly a member of the hominins, says Haile-Selassie. The latest specimen is “very much like the Ardipithecus foot, which I believe had many hominin features, so it’s likely to be a hominin”, agrees Daniel Lieberman, an anthropologist at Harvard University in Cambridge, Massachusetts, who was not involved in the study.
Good grasp of history
The discovery shows that one hominin lineage had grasping feet for at least a million years after Ar. ramidus. The creature was probably more agile in the trees than Au. afarensis but less nimble on two feet, says William Harcourt-Smith, an anthropologist at the City University of New York’s Lehman College. “We can only get a tantalizing glimpse at this, but its bipedal gait is likely to have been very different from Lucy’s and was probably a lot less efficient,” he says.
The finding will force a rethink regarding the course of early hominin evolution, Harcourt-Smith adds. The addition of a mystery hominin species at this crucial time period suggests that the new species' lineage split from that leading to Lucy earlier in hominin history, and provides further evidence against the idea that modern humans evolved via a linear progression of species from apes. “This [finding] is fascinating, and makes the evolution of this defining behaviour not a single, linear evolutionary event, but a far more complex affair,” Harcourt-Smith says.

Link to Nature Paper  

doi:10.1038/nature.2012.10342

 

The Burtele partial foot (BRT-VP-2/73). A laboratory photo after cleaning and preparation. It is shown here in its anatomically articulated form.
© The Cleveland Museum of Natural History

Million Genomes by 2014

Without a doubt the hottest company in the genomics sector right now is gene sequencing powerhouse Complete Genomics. In just the last four years the company has come out of nowhere to dominate the market for low cost sequencing of human genomes in large quantities. Although Complete Genomics is now slated to sequence an incredible 5,000 human genomes in 2010, this is nothing compared to what the company has in store for the years ahead.  Just days ago, in a Singularity Hub exclusive interview with Complete Genomics CEO Dr. Cliff Reid, we have learned that the company is now hoping to sequence 50,000 genomes in 2011 and a whopping 1 million genomes by 2014.