Some species of sharks have evolved to literally walk along the ocean floor (no, not on land) using their fins as feet. New research Conservation International’s Mark Erdmann and colleagues determined that walking sharks only evolved their unique capability 9 million years ago, "making them the 'youngest' sharks on our planet." Of course, a distinct species usually forms when some members of a species are physically separated from others. So how did that speciation occur in the case of the walking sharks? From an interview with Erdmann at Conservation International:
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For most of the walking shark species, our findings support the idea that speciation occurred because the populations slowly expanded their range by walking or swimming, then some individuals eventually became isolated by environmental factors such as sea level rise or the formation of large river systems that broke up their habitats.
For the four walking shark species found at the Bird’s Head Seascape, we suspect that they actually hitched a ride — on a drifting island...
Q: Is there another mystery about walking sharks you hope to solve?
From a scientific perspective, there is still so much to learn from walking sharks. We know that the world’s species that exist today are basically the existing “genetic reservoir” (raw genetic material) we have to adapt to global changes. We also know that walking sharks are very resilient to warm water and that they have a tolerance for oxygen deprivation. Any time you have an animal or plant that can survive in these extreme conditions, there is typically something unique about their genes — a “special sauce”.
In Las Cruces, New Mexico, police say they collected DNA from the spot where a suspect face-planted into a door while trying to escape. Read the rest
Almost 6,000 years ago on the island of Lolland, Denmark, a young girl disposed of her chewing gum. Now, University of Copenhagen researchers have used that gum, made from birch pitch, to sequence the girl's full genome. From Science:
The child had black hair, blue eyes, and dark skin, and was more closely related to hunter-gatherers from Western Europe than to farmers who had more recently settled in the region. She left traces of her most recent meal in the gum—she had been chewing hazelnuts and duck. But her oral microbiome also revealed that life could be hard—she had the Epstein-Barr virus and probably had suffered from mononucleosis in her life.
More in the scientific paper: "A 5700 year-old human genome and oral microbiome from chewed birch pitch" (Nature Communications) Read the rest
Russian scientist Denis Rebrikov claims that he's begun a gene-editing process to eventually enable couples who both carry a specific genetic mutation that causes deafness to birth children who can hear. Rebrikov formerly announced his effort to use the CRISPR tool for gene editing to create babies resistant to HIV. From Nature:
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In his e-mail to Nature, Rebrikov makes clear that he does not plan to create (a gene-edited) baby yet — and that his previously reported plan to apply this month for permission to implant gene-edited embryos in women has been pushed back.
Instead, he says that he will soon publish the results of his egg experiments, which also involved testing CRISPR’s ability to repair the gene linked to deafness, called GJB2, in bodily cells taken from people with this mutation. People with two mutated copies of GJB2 cannot hear well without interventions, such as hearing aids or cochlear implants. Rebrikov says these results will lay the groundwork for the clinical work.
Rebrikov adds that he has permission from a local review board to do his research, but that this does not allow transfer of gene-edited eggs into the womb and subsequent pregnancy...
Some scientists and ethicists also call into question the benefits of this procedure because hearing loss is not a fatal condition. “The project is recklessly opportunistic, clearly unethical and damages the credibility of a technology that is intended to help, not harm,” says Jennifer Doudna, a pioneer of the CRISPR gene-editing tool and a biologist at the University of California, Berkeley.
The U.S. Department of Justice (DOJ) this week released new rules that limit when police can access family tree DNA databases to identify crime suspects. This new genealogy policy is the first ever at the federal level to address how online genetic databases sold as services to the public can be used in law enforcement. Read the rest
An investigation by the health ministry in Guangdong, China determined that scientist He Jiankui broke national laws when he used the CRISPR gene-editing technique to engineer human embryos with resistance to HIV and then implanted the embryos into women who then birthed the babies. Based on the probe, the Southern University of Science and Technology has fired He from his position as a researcher and teacher there. According to an article in the Chinese state media outlet Xinhua, police may also explore charges against He and his colleagues. From Nature:
The Xinhua article confirms many details of the case for the first time: starting in June 2016, it says, He put together a team that, from March 2017, recruited eight couples consisting of an HIV-positive father and an HIV-negative mother. He’s team edited the genes of embryos from at least two couples. (The Xinhua article does not specify what type of gene editing was done, although He claims that the embryos were edited to remove a gene that enables HIV to enter cells.) In addition to the woman who already gave birth, one other woman involved in the experiment is currently pregnant with a gene-edited embryo. Five other couples are not pregnant, the article reports, and one couple dropped out of the experiment.
The article says that He’s gene-editing activities were “clearly prohibited by the state”, but it doesn’t mention which specific laws or regulations the researcher broke.
Today I learned that using cannabis can lower a fella's sperm count: those looking to partake in parenthood should take note. But that's not the only thing that cannabis can do to your swimmers. According to scientists from Duke University, using marijuana can cause genetic changes to sperm cells--something that could have far-reaching consequences for any baby a dude might father.
From The Verge:
For a study published today in the journal Epigenetics, scientists at Duke University compared the sperm of two groups of rats: those who had been given tetrahydrocannabinol (THC), the psychoactive ingredient in cannabis, and those who had not. Then they compared the sperm of 24 human men who smoked marijuana weekly versus a control group who used marijuana no more than 10 times in their life and not at all in the past half-year. In both cases — rats and humans — marijuana changed how genes work in sperm cells.
In both rats and humans, the cannabis affected many different genes involved in two different pathways. (Think of pathways as another set of instructions, this time for regulating various bodily functions.) One is important for organs to reach full size, and one plays a role in cancer and suppressing tumors.
Before anyone loses their shit, this doesn't mean that any kid you conceive while THC is coursing through your body will be more likely to get cancer. A lot more research needs to be conducted before any firm conclusions can be drawn. As The Verge points out, there were no laboratory controls on how much THC was consumed by the test subjects. Read the rest
A research team from Imperial College London have published promising results of an experiment in which Anopheles gambiae mosquitoes -- responsible for the spread of malaria -- were genetically modified with a stable, gene-drive-based CRISPR modification that caused them to go extinct in the lab. Read the rest
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
This is amazing. 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.
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