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At least 140 alternative RNA nucleotide forms exist. On mRNA, the most common is the methylation of adenosine on the N6 position (m6A).

Quintana-Murci and his colleagues also took advantage of a previously published map of areas of the human genome where Neanderthal genes are present, showing that innate immune genes are generally more likely to have been borrowed from Neanderthals than genes coding other types of proteins. Specifically, they noted that 126 innate immune genes in present-day Europeans, Asians, or both groups were among the top 5 percent of genes in the genome of each population most likely to have originated in Neanderthals. The cluster of toll-like receptor genes, encoding TLR 1, TLR 6, and TLR 10, both showed signs of having been borrowed from Neanderthals and having picked up adaptive mutations at various points in history. Meanwhile, a group led by Janet Kelso of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, used both the same previously published Neanderthal introgression map that Quintana-Murci used and a second introgression map. The researchers searched for borrowed regions of the genome that were especially long and common in present-day humans, eventually zeroing in TLR6, TLR10, and TLR1. These receptors, which detect conserved microbial proteins such as flagellin, are all encoded along the same segment of DNA on chromosome four.

In the 1950s, Idaho sheep ranchers had a problem. About a quarter of their lambs were being born dead or deformed-sometimes with a single eye centered in the middle of their forehead, like the Cyclops of Greek legend, or missing their upper jaw. There were times when the pregnant ewes couldn't give birth at all, carrying the mutated fetuses until they were surgically delivered or the ewes themselves died. Unbeknownst to the farmers, the cause was a poisonous plant, western false hellebore (Veratrum californicum). Eventually, the plant would inspire a successful cancer therapy-but at the time, the sheep were what mattered.

When it's completely unraveled, DNA is known to extend approximately six feet in length, yet is somehow able to cram itself into a cell's nucleus. In a study published today (July 27) in Science, researchers created a novel visualization method that revealed a 3-D glimpse of chromatin as it sits jam-packed within the nuclei of human cells. The researchers found that, contrary to how it's depicted in most textbooks, chromatin does not fold in on itself in an organized manner to create distinct structures. Instead, it forms a pliable, inconsistent chain characterized by a wide variety of folding patterns. 

Like humans, some golden retrievers develop Duchenne muscular dystrophy (DMD), a hereditary muscle wasting condition that begins early in life. Using gene therapy, scientists were able to restore muscle function in dogs with the disease, according to a study published today (July 25) in Nature Communications.

Following on the achievements of Chinese researchers, scientists in the United States have used CRISPR to manipulate the genomes of viable human embryos, MIT Technology Review reported yesterday (July 26). The work, not yet published, reportedly corrected defective genes from sperm donors in dozens of embryos, which were allowed to grow for several days.

In the study, published Monday (May 1) in Nature Biotechnology,  Luo and colleagues set their sights on two fusions genes they had previously found to be associated with prostate cancer and various forms of rapid and invasive cancer, including liver tumors. Using a modified CRISPR-Cas9 tool that creates a single- rather than double-stranded break in DNA, they targeted the chromosomal breakpoints that form these fusion genes and replaced fusion DNA with a gene encoding the enzyme HSV1-tk. This enzyme effectively kills tumor cells by converting the drug ganciclovir into its active form, which then blocks DNA synthesis and leads to cell death. (Ganciclovir is used to treat cytomegalovirus in humans.)

Over the past few decades, genetic research has revealed two deep truths about people. The first is that all humans are closely related-more closely related than all chimps, even though there are many more humans around today. Everyone has the same collection of genes, but with the exception of identical twins, everyone has slightly different versions of some of them. Studies of this genetic diversity have allowed scientists to reconstruct a kind of family tree of human populations. That has revealed the second deep truth: In a very real sense, all people alive today are Africans.