Sunday, October 25, 2009

Heritability and Demographic Analyses in the Large Isolated Population of Val Borbera Suggest Advantages in Mapping Complex Traits Genes

Genetic studies performed on heterogeneous populations make identifying rare variants for complex diseases difficult because of confounding variables associated with heterogeneous populations. This study collected genetic samples and medical information for 1803 people within a relatively isolated population. The authors report that analysis of the isolated population reveals significant heritability of medically relevant traits that might not have otherwise been uncovered with a more heterogeneous cohort.

Human DNA methylomes at base resolution show widespread epigenomic differences

Human genetic variation extends beyond differences in the underlying genetic sequence. A recent study reported in Nature provides a more robust understanding of DNA cytosine methylation, an alternate source of genetic variation. While DNA methylation was primarily associated with repeat CpG (Cytosine-phosphate-Guanine) rich portions of the genome, Lister et al. report that approximately 25% of methylation in embryonic stem cells occurs in non CpG portions of the genomes. CpG regions are associated with promoter regions of genes, and methylation of these regions are thought to regulate gene expression. The report of methylation in non CpG regions raises new questions about the role of this epigenetic modification. The publication also represents one of the first papers describing a relatively complete map of the human epigenome.

Saturday, October 24, 2009

A new primate phylogeny

The authors present a new primate phylogeny inferred from a supermatrix of mitochondrial and nuclear DNA. They also present dates of divergence and diversification rates for major clades in the order.

Where's the ecology in molecular ecology?

The authors review the types of papers published in journals such as Molecular Ecology and conclude that, in general, these journals aren't living up to their titles. Most papers are evolutionary rather than ecological. They highlight major questions in molecular ecology (the field of study) that are being addressed, as well as suggest future directions for molecular ecologists. Finally, they state that all ecologists need to be molecular ecologists in some shape or form if they are to completely understand patterns and processes in ecology.

Monday, October 19, 2009

Two Main Bottleneck Events Shaped Modern Human Genetic Diversity

Humans are widely thought to have expanded out Africa starting approximately 50,000 years ago. In this process, genetic variation was reduced the further populations moved away from Africa due to successive bottleneck events. The frequency and nature of these bottleneck events have already been extensively explored in the literature. A recent study, which analyzed 783 microsatellite loci genotyped on 53 globally representative populations, concludes that two major bottleneck events occurred in human history – the first occurring as humans moved out of Africa and the second as humans moved across the Bering Strait into the New World. These events can be detected due to the genetic implications of bottleneck events. After sharp declines in population numbers, excess heterozygosity exists in the population than would be expected given the number of alleles remaining. The authors used the program ‘Bottleneck’ to detect this signature. This study reconfirms the conventional understanding of human expansion.

Sunday, October 18, 2009

Comprehensive Mapping of Long-Range Interactions Reveals Folding Principles of the Human Genome

This report describes a method called Hi-C which can be used to map the dynamic configurations of whole genomes by coupling proximity-based ligation with massively parallel sequencing.

Monday, October 5, 2009

Mutations in LOXHD1...distrupt hair cell function, cause progressive hearing loss

Mutations in LOXHD1, an evolutionarily conserved stereociliary protein, distrupt hair cell function in mice and cause progressive hearing loss in humans. Findings suggest that age-dependent hair cell failure is a common mechanism for progressive autosomal-recessive nonsyndromic hearing loss (ARNSHL).

Sunday, October 4, 2009

Aging is RSKy Business

Science Magazine is dedicated to Ardipithecus ramidus this week, but I thought this review article was worth a look too. It discusses current research into longevity and the possibility of intervening in the human aging process.

Thursday, October 1, 2009

Ardipithecus ramidus

After 15 years of excavation and analysis, the folks working in Middle Awash, Ethiopia have finally published the description and interpretation of the anatomy and functional morphology of Ardipithecus ramidus. The have a partially complete female skeleton as well as bits and pieces of other individuals. They interpret "Ardi" as a dietary generalist who walked upright (though not like we would) on the ground, moved much like Old World monkeys in the trees and was fairly sexually monomorphic.