Dr. Kevin Foster, from the University of Oxford, visited the Center for Evolution and Medicine at Arizona State University last week to talk about competition and sociability among a variety of bacteria, some of which call our guts home. Using humorous descriptions of psychedelic broccoli, tiger and lion fights, and breathing on hornet’s nests, he walked us through the complexity of sociality found in microbes, which ranges from competition among specific bacterial cells to between-species cooperation. Foster used to study social insects, but now he applies his expertise of social behavior (and kin selection) to microbes. While kin selection provides an evolutionary explanation for many complex social behaviors in eukaryotic organisms, it may also be a good model to use in understanding the behavior of genetically similar microbes and how such behavior may affect human health.
There is a mature literature on evolution and aging intended to explain how, despite selection for the morphological, metabolic, physiological, and behavioral prerequisites for survival and procreation, with the passage of time bodies deteriorate ultimately resulting in death. The focus of such explanations is typically on concepts such as age-related variation in the potency of selection and the related notion of antagonistic pleiotropy (Fabian and Flatt, 2011), by which suggests that genes able to promote survival and reproductive success in youth may increase loss of function with age. These concepts address selection on intact organisms. In contrast, a recent article in Science (Goodell and Rando, 2015) contains an article addressing the role of selection directly on somatic cells and in particular tissue-specific stem cells. (more…)
Towards Xenografts in Clinical Transplantation: Multiplexed Negative Selection of Porcine Endogenous Retroviruses with CRISPR-Cas9
Clinical organ transplantation is now a large medical enterprise, with more than 29,000 organ transplants performed in 2014 in the United States alone (https://www.unos.org/data/transplant-trends/#transplants_by_organ_type+year+2014). Nevertheless, the number of organ donors is insufficient to meet the demand for new organs. For example, in the U.S. during 2014, there were 17,104 kidney transplants but 101,035 individuals on the waiting list for such transplants. Therefore, a recent study in Science (Yang et al., 2015) offers an important proof of principle for a necessary but not necessarily sufficient step on the path to safely using pig organs to substitute for failing human organs. (more…)
After posting my last commentary on the ongoing Ebola outbreak in West Africa, I listened to the netcast, This Week in Virology (www.twiv.tv), for September 14, 2014. TWiV sessions, hosted by Vincent Racaniello, a well-known virologist at Columbia University, are generally highly informative, typically offering thoughtful discussions about recently published studies pertaining to viruses or addressing broad areas of virus-related research. (more…)
A prion is a protein that can adopt a conformation other than the ‘standard’ functional conformation and this alternative conformation favors self-association. The aggregation-associated conformation can then be imposed on additional copies of the protein in the original conformation. This self-templating mechanism for propagation is known primarily for causing neurodegenerative conditions in humans and in animals, such as kuru or Creutzfeldt-Jakob disease in humans or bovine spongiform encephalopathy (i.e., mad cow disease) in cattle. Since this process of converting protein conformations can be transmitted from one animal to another or one person to another by some routes, such as cannibalism in the case of kuru, the name prion was created to indicate an infectious protein particle. This concept of an infectious agent that involved no nucleic acid was the basis for the Nobel Prize in Physiology or Medicine awarded to Stanley Prusiner in 1997 (http://www.nobelprize.org/nobel_prizes/medicine/laureates/1997/press.html). (more…)