By Oyang Teng, Biological Sciences ’14 Microbes are the planetary engineers of the biogeochemical cycles that sustain all life on earth. At the molecular scale, the biological turnover of such key elements as hydrogen, carbon, oxygen, nitrogen, iron and sulfur depends on the enzymatic transfer of electrons from reduced (electron-donating) to oxidized (electron-accepting) forms of these elements. On the global scale and over geological time, reduced substrates and oxidized products map to a vast, often circuitous flux between the interior depths of the mantle and the oceans, land, and atmosphere.
By Mubasher Ahmed, Genetics ‘15 Viral evolution is an emerging field in biology that has great implications for human health. T7 is a phage virus, meaning it infects bacteria, and is a powerful model system in evolutionary virology. In a recent experiment, a team of biologists sought to understand the degree to which genetic elements engineered into the T7 phage genome affected the phage’s rate of propagation. In this context, the genetic elements are sequences of DNA that are inserted between genes that allow for researchers to manipulate gene regulatory networks. This allows biologists to probe how phenotypes change when gene-gene interactions are perturbed. Previous studies had shown that such genomic elements led to decreased fitness for the virus, but these investigators hoped to better understand how exactly such a system would evolve in laboratory conditions. To address their questions, the scientists grew both T7 viruses with and without design […]
By Marisa Sanchez, Molecular and Cellular Biology ‘15 The genomes of male and female mammals differ by one chromosome. The Y chromosome is only present in males, and is responsible for initiating the physiological and morphological differences between the sexes. This has not always been the case though; at one point, the X and Y were identical, and over time the Y chromosome began to differentiate from the X chromosome and shrink in size. The Y chromosome today only has 20 genes, whereas the X chromosome has over 1,000 genes.