Yeast has brought a lot of joy into the world, but its evolutionary origins were unclear until scientists did a worldwide genomic survey of the humble organism. Based on the genetic diversity of strains found in China, they concluded that its origin is almost certainly in that part of the world. Read the rest
George Church's Harvard lab is one of the most celebrated fonts of innovation in the world of life sciences. George's earliest work on the Human Genome Project arguably pre-dated the actual start of that project. Subsequently, he's been involved in the creation of almost a hundred companies - 22 of which he co-founded.
Much of George's most recent and celebrated work has been with a transformationally powerful gene-editing technique called CRISPR, which he co-invented. George and I discuss CRISPR and its jarring ramifications throughout this week's edition of the After on Podcast. You can listen to our interview by searching "After On" in your favorite podcast app, or by clicking right here:
Our conversation begins with a higher-level survey of the field -- one which cleanly and clearly defines CRISPR by placing it into a broader, and also a quite fascinating framework. We cover four topics, which I'll now define up-front for you, so as to make the interview more accessible.
We begin by discussing genetic sequencing. "Sequencing" is a fancy (and rather cool way) of saying, "reading." Your genome is about three billion characters long. It's written in a limited alphabet, of just four letters: A, G, C, and T. And if someone sequences your genome, it simply means they've read it. They haven't modified it in any way. They haven't have cloned you. They've just gotten a readout (kind of like determining your blood type -- only a few billions times more complicated).
George and I next discuss gene editing. Read the rest
This is Ata, a bizarre, tiny mummified skeleton found in a deserted mining town in Chile's Atacama Desert in 2003.
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Scientists analyzed almost a quarter million DNA samples in the UK Biobank and found 538 new genes that appear to have a role in intellectual capabilities. Read the rest
A Scottish team of animal biotechnologists announced this week they successfully introduced human stem cells into sheep embryos. Perhaps one day we will all have our very own baaing organ donors.
The team are currently allowed to let the chimeric embryos develop for 28 days, 21 of which are in the sheep. While that might be sufficient to see the development of the missing organ when human cells are eventually combined with the genetically modified embryo, Dr Hiro Nakauchi of Stanford University, who is part of the team, said a longer experiment, perhaps up to 70 days, would be more convincing, although that would require additional permission from institutional review boards.
But, Ross said, for the approach to work it is thought that about 1% of the embryo’s cells would have to be human, meaning further work is needed to increase the proportion of human cells in the chimera.
Nakauchi also played down concerns: “The contribution of human cells so far is very small. It’s nothing like a pig with a human face or human brain,” he said
Who .... who said anything about... pigs with human faces and brains? Read the rest
Imagine that a folded note before you reveals -- definitively -- whether an excruciating, protracted neurological death lies a decade into your future. Should you look?
Do so, and you could be rid of the grim uncertainty. Or, you could be fated to live and die with an awful truth. One which will haunt you, but also let you shape your remaining years with a foreknowledge most of us lack.
This is a terrible quandary no one should face. But one person in 10,000 carries a genetic vulnerability to a gruesome affliction called Huntington’s Disease. You almost certainly do not. But for those with a family history of Huntington’s, the odds can be as high as 50/50. And in certain genetic configurations, the disease has 100% “penetrance” - meaning that all who carry the mutation are doomed. This makes the results of a Huntington’s test as close to an iron-clad prediction as genetics ever gets.
Before the test was created, a remarkably high percentage of people with family histories said they’d take it if given the chance. But once the test was available, roughly 90% of those people changed their minds. This makes it nigh impossible to know what we ourselves would do if faced with that choice.
But all of us will face a version of that choice very soon - albeit a far less stark, and radically more ambiguous version. And roughly 0.000% of us are in a position to make that choice in an adequately-informed and emotionally-prepared manner. Read the rest
Matthew Combs, a Fordham University Louis Calder Center Biological Field Station grad student worked with colleagues from Fordham and the Providence College Department of Biology to sequence the genomes of brown rats in Manhattan, and made a surprising discovery: the geography of rats has a genetic correlation, so a geneticist can tell where a rat was born and raised by analyzing its DNA.
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National Geographic interviewed geneticist Adam Rutherford, author of A Brief History of Everyone Who Ever Lived: The Stories in Our Genes. "In many ways, genetics makes a mockery of race," he notes. Read the rest
The field of epigenetics continues to make interesting discoveries about environmental effects on genetic material. A team led by Thomas McDade found that children's experiences affected their DNA, which in turn affected suscepitability to certain diseases. Via Smithsonian:
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Their investigation followed more than 500 children in the Philippines and found that certain childhood situations can create modifications in genes associated with inflammation, which affects how prone we are to suffer from certain illnesses. Specifically, these factors included socioeconomic status, the prolonged absence of a parent, the duration of breastfeeding, birth during the dry season, and exposure to microbes in infancy.
This cohort comprised over 3,000 pregnant women recruited in the Philippines in 1983. These women came from all different walks of life: They differed in access to clean water or a roof over their heads, whether they lived in an urban or a rural area, and whether they came into frequent contact with animals. From the data, they looked at over 500 of those women in order to figure out if their child’s environment growing up led to epigenetic modifications to their DNA—and later to a change in inflammatory proteins in their blood in adulthood.
Once their children were born, the investigators kept track of them and of the environments they were exposed to throughout their lives. Once they turned 21, the investigators took a blood sample that they used to measure the DNA methylation throughout their genome, as well as inflammation-related proteins that have been previously associated with cardiovascular diseases and other aging-related diseases.
The psilocybin in magic mushrooms is a potent psychedelic for animals. But what good is the psilocybin for the shrooms? New genetic research from Ohio State University suggests that the psilocybin might act as an insect repellant, protecting the mushrooms. From New Scientist:
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The gene cluster (linked to psilocybin production) is found in several distantly related groups, suggesting that the fungi swapped genes in a process called horizontal gene transfer. This is uncommon in mushrooms: it is the first time genes for a compound that is not necessary for the fungi’s survival – called a secondary metabolite – have been found moving between mushroom lineages.
Since these genes have survived in multiple species, Slot thinks psilocybin must be useful to the fungi. “Strong selection could be the reason this gene cluster was able to overcome the barriers to horizontal gene transfer,” (researcher Jason Slot) says.
Hallucinogenic mushrooms often inhabit areas rich in fungi-eating insects, so Slot suggests psilocybin might protect the fungi, or repel insects from a shared food source, by somehow influencing their behaviour.
British geneticist Adam Rutherford is one of the country's great science communicators, an alumnus of Nature
whose work we've celebrated here
for many years
; with his second book, A Brief History of Everyone Who Ever Lived
, Rutherford reveals how the century's astounding advances in genetic science reveal just how little we understand about our genes -- and how our ideas about race and heredity are antiquated superstitions that reflect our biases more than our DNA. (See the bottom of this post for an important update about the upcoming US edition!
One of the most hotly-contested fields of genetics revolves around the genetic lineage of ancient Egyptians. A new study of 90 Pre-Ptolemaic, Ptolemaic, and Roman mummies raises as many questions as it answers. Read the rest
If you're among the one in four people who sneeze when you move from a dark place into the sunlight, this nifty little explainer from a fellow traveler gives a great overview of causation theories over the millennia. Turns out it is just one transposed letter in the second chromosome that causes the effect. Read the rest
Meet Lucky, a two-faced calf who lives in Campbellsville, Kentucky. Lucky is just over a month old but may be the oldest animal of its kind to survive with the genetic abnormality, called diprosopus. From National Geographic:
The calf was named Lucky by the McCubbins' five-year-old daughter, Henley, after her parents told her the rare animal was lucky to be alive. Most such genetic or developmental defects are aborted in the womb, although a few make it to birth. Most of those die within a few days.
For a two-faced or two-headed animal to make it to adulthood is extremely rare. It's considered ultrarare in the wild, although two-faced cat "Frank and Louie" lived to at least 12 years old, thanks to the care of its owners.
So far, Lucky has been doing well, the McCubbins said, although the middle two of her eyes don't work. She can only walk in circles and falls down a lot.
Lucky needs some help eating, and both mouths move at the same time.
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Eliza writes, "A researcher from Lehigh University has invented a light-based pacemaker for fruit flies, and says a human version is 'not impossible.' The pacemaker relies on the new technique of 'optogenetics,' in which light-sensitive proteins are inserted into certain cells, allowing those cells to be activated by pulses of light. Here, the proteins were inserted into cardiac cells so the researchers could trigger the contractions that produce heartbeats." Read the rest
I've heard -- and repeated -- the theory that addiction rates among indigenous people in the Americas was caused by genetics -- specifically, that "new world" populations hadn't gone through the European plague years' genetic bottleneck that killed everyone who couldn't survive on alcoholic beverages (these having been boiled during their production and thus less likely to carry infectious diseases). Read the rest