Toxins: An Unlikely Driver of Human Evolution

A recent article in the NYT by Carl Zimmer discusses the roll poisons may have played in our evolutionary history. The high arid altitudes of the Andes contain abnormally high levels of arsenic, leading some to believe that local populations would need to have some adaptive advantage to survive. The study published in the Society for Molecular Biology and Evolution looked at small human population in the Argentinian Andes and genotyped women from the population for 4,301,332 SNPs. They discovered that of specific variation in the gene AS2MT plays a role in the metabolization of Arsenic. This variation was disproportionately present in the Andes populations when compared to populations found outside of the arsenic-rich environment, providing the first demonstration of how toxins shape human evolution.

Non-Invasive Prenatal Screening - Cocktail Chatter March 30

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This article discussed a statement that had been released by two of world's largest societies of human geneticists. The statement talked about the research that had been done on non-invasive prenatal screening, both the benefits and the downsides. The article discussed and compared the present-day technology which is combined First trimester screening with the new procedure. The article then proceeded to talk about how this procedure would be implemented and how it could help the public.

         Original:

Wybo Dondorp, Guido de Wert, Yvonne Bombard, Diana W Bianchi, Carsten Bergmann, Pascal Borry, Lyn S Chitty, Florence Fellmann, Francesca Forzano, Alison Hall, Lidewij Henneman, Heidi C Howard, Anneke Lucassen, Kelly Ormond, Borut Peterlin, Dragica Radojkovic, Wolf Rogowski, Maria Soller, Aad Tibben, Lisbeth Tranebjærg, Carla G van El, Martina C Cornel. Non-invasive prenatal testing for aneuploidy and beyond: challenges of responsible innovation in prenatal screening. European Journal of Human Genetics, 2015; DOI: 10.1038/ejhg.2015.57

Online:  http://www.sciencedaily.com/releases/2015/03/150325132611.htm

Fish with the Secrets to Human Aging

In this article, the lifespan of turquoise killifish is examined as a proxy for human aging. Turquoise killifish are the shortest-lived vertebrate species studied in labs. Though greatly expedited, researchers have discovered that the mechanisms of aging in turquoise killifish are very similar to human beings.

To closely examine the mechanisms of aging in killifish, the entire genome of the killifish was sequnced, looking specifically at regions known to be associated with aging in mice and humans. Researchers then inserted new genes into the killifish genome, specifically TERT. TERT encodes for a protein that builds and protects DNA telomeres (which have been found to a play a role in aging).

In this study researchers altered the TERT gene in killifish so that it was no longer functional. This had catastrophic effects on adult killifish, leading to early infertility, gastrointestinal atrophy, blood thinning, among other defects associated with typical aging. However, despite these shortcomings, killifish with non-functional TERT did not die at ages significantly lower than that of functional TERT fish. This preliminary research suggested telomerase deficiency plays a significant role in the onset of age related pathologies.

NYTimes Article: http://www.nytimes.com/2015/03/03/science/in-short-lived-fish-secrets-to-aging.html?rref=collection%2Fcolumn%2Fmatter

Original Publication: http://www.cell.com/cell/abstract/S0092-8674(15)00116-6?cc=y

Some genes 'foreign' in origin and not from our ancestors

Evidence has been found for substantial horizontal gene transmission between microorganisms and animals. Although horizontal gene transmission is common in bacteria and has been observed previously in less complex animals such as worms, it was not previously shown that more complex animals, including humans, carried large numbers of genes acquired via horizontal gene transmission. Crisp et al at the University of Cambridge studied full genomes in 26 animal species to identify foreign genes acquired via horizontal gene transmission. Although they found only 33 foriegn genes (very few compared to rates in bacteria), this was still many more than had been previously documented, and many of them were involved in crucial processes. The 33 genes found are involved in lipid metabolism, inflammatory response, immune cell signalling, and antimicrobial responses, as well as amino-acid metabolism, protein modification and antioxidant activities. While the majority of the foreign genes came from bacteria and protists, there were also some with viral and fungal origins. The introduction of this foreign DNA in the animal lineage, believed to have been acquired sometime between the origins of Chordata and the last common ancestor of all extant primates, may have had important evolutionary ramifications in the animal lineage.

Science Daily article: http://www.sciencedaily.com/releases/2015/03/150312123319.htm

Original source: Alastair Crisp, Chiara Boschetti, Malcolm Perry, Alan Tunnacliffe, Gos Micklem. Expression of multiple horizontally acquired genes is a hallmark of both vertebrate and invertebrate genomes. Genome Biology, 2015; 16 (1). http://genomebiology.com/2015/16/1/50