The Russian community of geneticists, clinicians and bioethicists have reached a consensus on the use of genome-editing technologies on human embryos and germ cells for clinical purposes. They consider that such experiments are premature at this point. Their view aligns with the position of the Russian ministry of health and sets the social context for further discussion of the technology.
Russian biologist Denis Rebrikov has started gene editing in eggs donated by women who can hear to learn how to allow some deaf couples to give birth to children without the genetic mutation that impairs hearing. The news, detailed in an e-mail he sent to Nature on 17 October, is the latest in a saga that kicked off in June, when Rebrikov told Nature of his controversial intention to create gene-edited babies resistant to HIV using the popular CRISPR tool.Rebrikov’s latest e-mail follows a September report in Russian magazine N+1 that one deaf couple had started procedures to procure eggs that would be used to create a gene-edited baby — but the eggs that Rebrikov has edited are from women without the genetic mutation that can impair hearing. He says the goal of the experiments is to better understand potentially harmful ‘off-target’ mutations, which are a known challenge of using CRISR–Cas9 to edit embryos.
Authors:Bull et alAbstract:A central topic for conservation science is evaluating how human activities influence global species diversity. Humanity exacerbates extinction rates. But by what mechanisms does humanity drive the emergence of new species? We review human-mediated speciation, compare speciation and known extinctions, and discuss the challenges of using net species diversity as a conservation objective. Humans drive rapid evolution through relocation, domestication, hunting and novel ecosystem creation—and emerging technologies could eventually provide additional mechanisms. The number of species relocated, domesticated and hunted during the Holocene is of comparable magnitude to the number of observed extinctions. While instances of human-mediated speciation are known, the overall effect these mechanisms have upon speciation rates has not yet been quantified. We also explore the importance of anthropogenic influence upon divergence in microorganisms. Even if human activities resulted in no net loss of species diversity by balancing speciation and extinction rates, this would probably be deemed unacceptable. We discuss why, based upon ‘no net loss’ conservation literature—considering phylogenetic diversity and other metrics, risk aversion, taboo trade-offs and spatial heterogeneity. We conclude that evaluating speciation alongside extinction could result in more nuanced understanding of biosphere trends, clarifying what it is we actually value about biodiversity.
Three weeks ago, 130 scientists, entrepreneurs and policy leaders held an invitation-only, closed-door meeting at Harvard University to discuss an ambitious plan to create synthetic human genomes. Now, after a flurry of criticism over the secrecy of the effort, the participants have published their idea, declaring that they're launching a project to radically reduce the cost of synthesizing genomes -- a potentially revolutionary development in biotechnology that could enable technicians to grow human organs for transplantation.
Earlier this week, over a hundred scientists, lawyers, and entrepreneurs gathered to discuss the radical possibility of creating a synthetic human genome. Strangely, journalists were not invited, and attendees were told to keep a tight lip. Which, given the weighty subject matter, is obvious cause for concern.
Many safety, technical and legal barriers still stand in the way of editing DNA in human embryos. But some scientists and ethicists say that it is important to think through the implications of embryo editing now — before these practical hurdles are overcome. What sort of world would these procedures create for those currently living with disease and for future generations?
Researchers in China say that they have discovered a way to make rudimentary mouse sperm in a dish, and used them to produce offspring.
If the claim stands up to scrutiny, it could point the way to making human sperm in the lab for fertility treatments. But some scientists are not convinced by the report, which is published today inCell Stem Cell.
“The results are super-exciting and important,” says Jacob Hanna, a stem-cell scientist at the Weizmann Institute of Science in Rehovot, Israel. But Takashi Shinohara, a reproductive biologist at Kyoto University in Japan, is among researchers who have doubts about the work: he notes that scientists have struggled to replicate several previous claims that sperm can be made in a dish.
In 2011, molecular biologists led by Mitinori Saitou at Kyoto University reported that they had managed to recreate the first stages of sperm development in a dish. They coaxed mouse embryonic stem cells to become cells that resembled primordial germ cells (PGCs)—an important stage in the development of both eggs and sperm.
Saitou's team then implanted the artificial PGCs into a mouse: when implanted in testes, they grew to become sperm; in ovaries, they matured into eggs.
New geological and palaeontological age constraint for the gorilla–human lineage split
Authors:
Kotah et al
Abstract:
The palaeobiological record of 12 million to 7 million years ago (Ma) is crucial to the elucidation of African ape and human origins, but few fossil assemblages of this period have been reported from sub-Saharan Africa. Since the 1970s, the Chorora Formation, Ethiopia, has been widely considered to contain ~10.5 million year (Myr) old mammalian fossils. More recently, Chororapithecus abyssinicus, a probable primitive member of the gorilla clade, was discovered from the formation. Here we report new field observations and geochemical, magnetostratigraphic and radioisotopic results that securely place the Chorora Formation sediments to between ~9 and ~7 Ma. The C. abyssinicus fossils are ~8.0 Myr old, forming a revised age constraint of the human–gorilla split. Other Chorora fossils range in age from ~8.5 to 7 Ma and comprise the first sub-Saharan mammalian assemblage that spans this period. These fossils suggest indigenous African evolution of multiple mammalian lineages/groups between 10 and 7 Ma, including a possible ancestral-descendent relationship between the ~9.8 Myr old Nakalipithecus nakayamai and C. abyssinicus. The new chronology and fossils suggest that faunal provinciality between eastern Africa and Eurasia had intensified by ~9 Ma, with decreased faunal interchange thereafter. The Chorora evidence supports the hypothesis of in situ African evolution of the Gorilla–Pan–human clade, and is concordant with the deeper divergence estimates of humans and great apes based on lower mutation rates of ~0.5 × 10−9 per site per year.
An experimental assisted reproduction technique that could allow some families to avoid having children with certain types of heritable disease should be allowed to go forward in the United States, provided it proceeds slowly and cautiously. That is the conclusion of a report released today from a panel organized by the U.S. National Academies of Sciences, Engineering, and Medicine (NAS), which assesses the ethics questions surrounding the controversial technique called mitochondrial DNA replacement therapy.
More controversially, however, the panel recommended that only altered male embryos should be used to attempt a pregnancy, to limit the possible risks to future generations. (Males can’t pass along the mitochondrial DNA that is altered in the procedure.)
Insomniacs take heart: Humans get by on significantly less sleep than our closest animal relatives. The secret, according to a new study, is that our sleep is more efficient.
Researchers from Duke University scoured the scientific literature and compiled a database of slumber patterns across hundreds of mammals including 21 species of primates -- from baboons and lemurs to orangutans, chimpanzees and people. They then used statistical techniques to account for each species' position in the primate family tree.
They found that humans are exceptionally short sleepers -- getting by on an average of seven hours of sleep a night, whereas other primate species, such as southern pig-tailed macaques and gray mouse lemurs, need as many as 14 to 17 hours.
What's more, our sleep tends to be more efficient, meaning we spend a smaller proportion of time in light stages of sleep, and more of our sleep time in deeper stages of sleep. A dream state called rapid eye movement sleep, or REM, for example, makes up nearly 25 percent of our overall sleep. But in primates such as mouse lemurs, mongoose lemurs and African green monkeys, REM sleep barely climbs above five percent.
"Humans are unique in having shorter, higher quality sleep," said anthropologist and study co-author David Samson of Duke, who logged nearly 2,000 hours watching orangutans in REM and non-REM sleep as part of his dissertation research prior to coming to Duke.
Don't look now, but the future just pulled into town.
Hundreds of scientists, policymakers and the president's science adviser have gathered Tuesday in Washington for what will be a three-day summit on genetic engineering, with a focus on a new, relatively simple technique for manipulating genes. It's fast and flexible, and just about anybody with some lab equipment and a little know-how can potentially alter the human species. The technique is called CRISPR-Cas9, or simply CRISPR, and more generically referred to as "gene editing."
The summit kicked off early Tuesday morning at the headquarters of the National Academy of Sciences, which is one of the sponsors, along with the National Academy of Medicine, the Royal Academy (Britain), and the Chinese Academy of Sciences. The Chinese scientists have been aggressive in using CRISPR, and one team made news this year when it reported results from experiments on nonviable human embryos.
“The overriding question is when, if ever, we will want to use gene editing to change human inheritance," summit chair David Baltimore of Caltech said in his introductory remarks.
Genetic material from ancient viral infections is critical to human development, according to researchers at the Stanford University School of Medicine.
They've identified several noncoding RNA molecules of viral origins that are necessary for a fertilized human egg to acquire the ability in early development to become all the cells and tissues of the body. Blocking the production of this RNA molecule stops development in its tracks, they found.
The discovery comes on the heels of a Stanford study earlier this year showing that early human embryos are packed full of what appear to be viral particles arising from similar left-behind genetic material.
"We're starting to accumulate evidence that these viral sequences, which originally may have threatened the survival of our species, were co-opted by our genomes for their own benefit," said Vittorio Sebastiano, PhD, an assistant professor of obstetrics and gynecology. "In this manner, they may even have contributed species-specific characteristics and fundamental cell processes, even in humans."
Sebastiano is a co-lead and co-senior author of the study, which will be published online Nov. 23 in Nature Genetics. Postdoctoral scholar Jens Durruthy-Durruthy, PhD, is the other lead author. The other senior author of the paper is Renee Reijo Pera, PhD, a former professor of obstetrics and gynecology at Stanford who is now on the faculty of Montana State University.
Sebastiano and his colleagues were interested in learning how cells become pluripotent, or able to become any tissue in the body. A human egg becomes pluripotent after fertilization, for example. And scientists have learned how to induce other, fully developed human cells to become pluripotent by exposing them to proteins known to be present in the very early human embryo. But the nitty-gritty molecular details of this transformative process are not well understood in either case.
They are meeting in China; they are meeting in the United Kingdom; and they met in the United States last week. Around the world, scientists are gathering to discuss the promise and perils of editing the genome of a human embryo. Should it be allowed — and if so, under what circumstances?
The meetings have been prompted by an explosion of interest in the powerful technology known as CRISPR/Cas9, which has brought unprecedented ease and precision to genetic engineering. This tool, and others like it, could be used to manipulate the DNA of embryos in a dish to learn about the earliest stages of human development. In theory, genome editing could also be used to 'fix' the mutations responsible for heritable human diseases. If done in embryos, this could prevent such diseases from being passed on.
The prospects have prompted widespread concern and discussion among scientists, ethicists and patients. Fears loom that if genome editing becomes acceptable in the clinic to stave off disease, it will inevitably come to be used to introduce, enhance or eliminate traits for non-medical reasons. Ethicists are concerned that unequal access to such technologies could lead to genetic classism. And targeted changes to a person's genome would be passed on for generations, through the germ line (sperm and eggs), fuelling fears that embryo editing could have lasting, unintended consequences.
If you have diabetes, or cancer or even heart problems, maybe you should blame it on your dad's behaviour or environment. Or even your grandfather's. That's because, in recent years, scientists have shown that, before his offspring are even conceived, a father's life experiences involving food, drugs, exposure to toxic products and even stress can affect the development and health not only of his children, but even of his grandchildren.
But, despite a decade of work in the area, scientists haven't been able to understand much about how this transmission of environmental memories over several generations takes place. McGill researchers and their Swiss collaborators think that they have now found a key part of the molecular puzzle. They have discovered that proteins known as histones, which have attracted relatively little attention until now, may play a crucial role in the process.
They believe that this finding, which they describe in a paper just published in Science, has the potential to profoundly change our understanding of how we inherit things. That's because the researchers show that there is something apart from DNA that plays an important role in inheritance in general, and could determine whether a father's children and grandchildren will be healthy or not.
The US House of Representatives is wading into the debate over whether human embryos should be modified to introduce heritable changes. Its fiscal year 2016 spending bill for the US Food and Drug Administration (FDA) would prohibit the agency from spending money to evaluate research or clinical applications for such products.
In an unusual twist, the bill—introduced on June 17—would also direct the FDA to create a committee that includes religious experts to review a forthcoming report from the US Institute of Medicine (IOM). The IOM's analysis, which considers the ethics of creating embryos that have three genetic parents, was commissioned by the FDA.
The House legislation comes during a time of intense debate on such matters, sparked by the announcement in April that researchers in China had edited the genomes of human embryos. The US National Institutes of Health (NIH) moved quickly to remind the public that a 1996 law prevents the federal government from funding work that destroys human embryos or creates them for research purposes.
In a world first, Chinese scientists have reported editing the genomes of human embryos. The results are published in the online journal Protein & Cell and confirm widespread rumours that such experiments had been conducted—rumours that sparked a high-profile debate last month about the ethical implications of such work.
In the paper, researchers led by Junjiu Huang, a gene-function researcher at Sun Yat-sen University in Guangzhou, tried to head off such concerns by using 'non-viable' embryos, which cannot result in a live birth, that were obtained from local fertility clinics. The team attempted to modify the gene responsible for β-thalassaemia, a potentially fatal blood disorder, using a gene-editing technique known as CRISPR/Cas9. The researchers say that their results reveal serious obstacles to using the method in medical applications.
"I believe this is the first report of CRISPR/Cas9 applied to human pre-implantation embryos and as such the study is a landmark, as well as a cautionary tale," says George Daley, a stem-cell biologist at Harvard Medical School in Boston. "Their study should be a stern warning to any practitioner who thinks the technology is ready for testing to eradicate disease genes."
Researchers from Cambridge University and Israel’s Weizmann Institute of Science are claiming a stem cell research breakthrough that would allow a baby to be created from the skin cells from two adults, no matter their gender. This potentially allows for infertile couples to have their own children without resorting to sperm or egg donors, and may provide the means for same sex couples to produce their own babies.
Previously only successful in experiments on mice, the new research has been conducted on human cells for the first time. In this study, the researchers paired stem cell lines from embryos with the skin of a range of different adults, with the resultant cells compared to aborted fetuses to determine an identical match.
Techniques devised to create same-sex offspring are not new. Some experiments involve the manipulation of fibroblasts in mice resulting in offspring with the genetic traits of multiple male mice, whilst others have used bone marrow stem cells extracted from males to trigger spermatogonia.
However, in this latest research, stem cells and adult human skin have been combined for the first time to create an entire new germ-cell line (that is, cells that will become embryos). Derived from ten different donor sources, the new germ-cell lines were created from 10 different donor sources – five embryos and five adults.
Refining human palaeodietary reconstruction using amino acid δ15N values of plants, animals and humans
Authors:
Styring et al
Abstract:
An established method of estimating the trophic level of an organism is through stable isotope analysis of its tissues and those of its diet. This method has been used in archaeology to reconstruct past human diet from the stable nitrogen isotope (δ15N) values of human and herbivore bone collagen. However, this approach, using the 15N-enrichment of human bone collagen δ15N values over associated herbivore bone collagen δ15N values to predict the relative importance of animal protein, relies on the assumptions that: (i) the δ15N values of plants consumed by humans and herbivores are identical, and (ii) the 15N-enrichment between diet and consumer is consistent. Bone collagen amino acid δ15N values have the potential to tackle these uncertainties, as they constrain the factors influencing bone collagen δ15N values. In this study, the δ15N values of glutamic acid and phenylalanine in human and herbivore bone collagen isolates from Neolithic sites in Germany, Greece and Turkey were determined by gas chromatography-combustion-isotope ratio mass spectrometry. The fraction of animal protein in total dietary protein consumed by the humans was estimated by: (i) comparing bulk human and herbivore collagen δ15N values, (ii) comparing bulk human and herbivore collagen and ancient charred cereal grain δ15N values, (iii) comparing human bone collagen δ15NGlutamic acid and δ15NPhenylalanine values, and (iv) comparing δ15NGlutamic acid values of human and herbivore bone collagen and estimated δ15NGlutamic acid values of ancient charred cereal grains. Where determined cereal grain δ15N values are higher than estimated herbivore forage values, estimates of animal protein consumption are significantly lower, emphasising the importance of the plant nitrogen contribution to human bone collagen. This study also highlights the need for further investigation into: (i) the Δ15NConsumer-Diet values of glutamic acid and phenylalanine in terrestrial ecosystems, and (ii) Δ15NGlutamic acid-Phenylalanine values of common plant foods in order to improve the accuracy and more widespread applicability of amino acid-based methods for palaeodietary reconstruction.
Whole-Genome Sequencing of the World’s Oldest People
Authors:
Gierman et al
Abstract:
Supercentenarians (110 years or older) are the world’s oldest people. Seventy four are alive worldwide, with twenty two in the United States. We performed whole-genome sequencing on 17 supercentenarians to explore the genetic basis underlying extreme human longevity. We found no significant evidence of enrichment for a single rare protein-altering variant or for a gene harboring different rare protein altering variants in supercentenarian compared to control genomes. We followed up on the gene most enriched for rare protein-altering variants in our cohort of supercentenarians, TSHZ3, by sequencing it in a second cohort of 99 long-lived individuals but did not find a significant enrichment. The genome of one supercentenarian had a pathogenic mutation in DSC2, known to predispose to arrhythmogenic right ventricular cardiomyopathy, which is recommended to be reported to this individual as an incidental finding according to a recent position statement by the American College of Medical Genetics and Genomics. Even with this pathogenic mutation, the proband lived to over 110 years. The entire list of rare protein-altering variants and DNA sequence of all 17 supercentenarian genomes is available as a resource to assist the discovery of the genetic basis of extreme longevity in future studies.
