Blogs / 80beats

The Vatican has issued new ethical guidelines in response to the biomedical advances of the last 20 years, and has come down hard on assisted reproduction technologies and genetic engineering. The document, Dignitas Personae (which translates as “human dignity”), reaffirm the church’s opposition to in vitro fertilization. It also tells Catholics that the church also doesn’t condone “adopting” leftover fertilized embryos from fertility clinics, and frowns upon the genetic testing of embryos before implantation, which could lead to the embryo being discarded. The Vatican says these techniques violate the principles that every human life — even an embryo — is sacred, and that babies should be conceived only through intercourse by a married couple [The New York Times].

These instructions stem from two fundamental theological principles: that life begins at conception and that the origin of human life is the “fruit of marriage.” … The document now makes clear that the morning-after pill, RU-486, and intrauterine devices (IUDs), which either intercept the embryo before implantation or eliminate it after implantation, “fall within the sin of abortion” [Scientific American]. The guidelines may come as a surprise to many Catholics who don’t realize that the church takes such a strict stance on medical technologies like in vitro fertilization that are often seen as routine and beneficial.

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Genetically engineered bacteria can now produce long-chain alcohols that could be used as biofuel, scientists report in the Proceedings of the National Academy of Sciences [subscription required]. Remarkably, the researchers synthetically modified the bacteria’s metabolism to churn out a type of energy-rich alcohol not normally found in nature. “Previous metabolic engineering work typically produces compounds that already exist in nature,” says coauthor James Liao… “Our work here aims to produce compounds that are not synthesized in nature” [Science News].

In addition to ordinary genetic engineering, which involves taking genes from different species (in this case, genes from yeast and a cheese-making bacteria), the new study also required a third, custom-made artificial gene. The three genes were inserted into the genome of E. coli bacteria. The researchers designed the genes to extend E. coli’s metabolic pathway so that toward the end, the precursor compounds that would normally get converted into amino acids instead turn into long-chain alcohols [Technology Review]. These long-chain alcohols string together six carbon atoms, packing in more potential energy per molecule. Ethanol has only two carbon atoms, and no other naturally-occurring alcohol contains more than five.

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The genome of the woolly mammoth is halfway sequenced and science-fiction fanatics are once again talking about resurrecting extinct species–except this time, the scientists are talking too. Researchers at Pennsylvania State University extracted DNA from the hair of two woolly mammoths found in the permafrost of Siberia; one lived about 20,000 years ago, the other about 60,000 years ago. Reporting in Nature [subscription required], the researchers say they have already sequenced more than three billion base pairs of the mammoth genome, and they say there should be no technical obstacles to sequencing the complete genome. “It’s a technical breakthrough,” says ancient-DNA expert Hendrik N. Poinar [Scientific American].

Access to clumps of preserved mammoth hair was essential to the researchers’ success. The tough keratin that makes up the hair encased the mammoth’s DNA and separated it from any alien fragments, keeping these samples more pure [New Scientist]. Horns and feathers are also made of keratin, broadening the prospects of sequencing other extinct species from museum specimens.

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The germ-fighting power of bleach lies in its ability to unravel cellular proteins, according to a new study. Researchers at the University of Michigan report that the active ingredient in bleach, hypochlorous acid, irreparably alters the three-dimensional structure of proteins in living cells—to fatal effect. They also found that some bacteria possess a special protein that can somewhat counter the ravages of hypochlorous acid. The findings clear up a hitherto murky understanding of how the common household cleaner does its job. “Everyone knew that bleached worked, and that was enough,” says [researcher Ursula Jacob]. “Few really cared how it worked” [Nature News].

In fact, Jacob’s team didn’t set out to answer that question either. They were studying a bacterial protein known as heat shock protein 33 (Hsp33) that helps other proteins maintain their proper shapes. Hsp33 is activated in times of stress, such as when the bacteria is exposed to high temperatures. “At high temperatures, proteins begin to lose their three-dimensional molecular structure and start to clump together and form large, insoluble aggregates, just like when you boil an egg,” said study lead author Jeannette Winter… Like a boiled egg, those proteins can never revert to their previous state, and the stressed cells eventually die [LiveScience.com].

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Scientists say they have bred super immune cells that are able to recognize and destroy many variants of HIV-infected cells. The news comes after a bleak year for AIDS research that saw the failure of the Merck HIV vaccine trial and the cancellation of another. “I think the field as a whole has been taking a step back and thinking we need some different ideas all together,” [New Scientist] said immunologist Philip Goulder.

The researchers’ novel idea was to create a mutant type of immune cells, called T-cells, that would target SL9, a protein that is part of HIV and also appears on the surface of HIV-infected cells. They started with particularly strong T-cells taken from a patient who had resisted HIV infection. “When we tested the T cells from this patient, it looked as if he was responding to a number of those variants that normally escape the immune system,” [The Guardian] said researcher Brent Jakobsen. Through a process of directed evolution, the researchers selected for T-cell mutants that had receptors enhanced to recognize and latch onto SL9. In Nature Medicine [subscription required], the researchers report that in lab cultures of human cells, the souped-up T-cells easily destroyed HIV-infected cells and even recognized tricky variants of the SLP9 protein.

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In a big step forward for cloning research, scientists have produced healthy clones of mice that were dead and frozen for 16 years. Researchers say the new technique could allow conservationists to freeze tissue from endangered species, which could then be used to produce clones if those species become extinct. The finding also raises hopes of one day being able to resurrect extinct animals frozen in permafrost, such as the woolly mammoth, says [lead researcher] Teruhiko Wakayama…. “It would be very difficult, but our work suggests that it is no longer science fiction,” he says [New Scientist].

Researchers have previously produced clones from frozen animal tissue, but only from specimens that were preserved with special chemicals to protect cells from damage during the deep freeze. In this study, published in the Proceedings of the National Academy of Sciences [subscription required], no such special precautions were taken when the mice were stowed in a freezer 16 years ago. Many zoos are not in a position to collect cells and freeze them in such a way as to preserve their viability, says [cloning expert] Robert Lanza … but they can put a dead animal “in a plastic bag and throw it in the freezer”, he adds. “With a kitchen freezer you could store the genetic diversity of every panda in existence” [New Scientist].

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Using a gene from a snapdragon flower, researchers have created a purple tomato rich in antioxidants, and a new study has shown that cancer-prone mice that were fed the altered tomatoes had significantly longer lifespans than those that dined on regular tomatoes. The tomatoes’ purple hue was a side effect of the type of antioxidants produced, called anthocyanins.

The tomatoes produce levels of anthocyanins about on par with blackberries, blueberries and currants, which recent research has touted as miracle fruits. But because of the high cost and infrequent availability of such berries, tomatoes might be a better source, says [lead researcher Cathie] Martin [USA Today].

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Researchers have created a “biocomputer” out of strands of RNA inside a living yeast cell, and demonstrated that it can be programmed to respond to conditions within the cell by taking specific actions. Like the most basic computers, the RNA device operates on a simple system of Boolean logic—it can be programmed to respond to the commands AND, OR, NAND and NOR.

The invention could have a wide range of applications, researchers say. Bio-computers might eventually serve as brains for producing biofuels from cells, for example, or to control “smart drugs” that medicate only under certain conditions. For example, a smart drug could sample a cellular environment and trigger a self-destruct sequence if disease is detected, [study coauthor Christina] Smolke said [National Geographic News].

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Researchers have found a way to create stem cells from adult liver cells without triggering DNA changes that have caused mutations and tumors in previous studies. Though demonstrated only in mice so far, the result marks another key achievement in the fledgling science of cellular reprogramming. The hope is to create human, embryonic-like stem cells — which can be turned into all the other tissue types of the body — without using eggs or destroying embryos. That freshly derived tissue could then be transplanted into patients to treat various diseases [The Wall Street Journal].

A method of using adult cells to create stem cells was debuted by Japanese researchers in 2006. By using viruses to insert key developmental genes, researchers coaxed human skin cells into an embryonic state, capable of growing into almost any other type of tissue…. But there was a catch: Viruses used to reset the cells tended to fuse with their DNA, leading to unpredictable mutations and cancer. The cells were promising in principle, but couldn’t be used medically [Wired News]. In the new breakthrough, researchers used a different kind of virus to introduce the genes, and found that it didn’t leave behind any damaging genetic code.

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The introduction of genetically engineered cotton plants has had an unexpectedly broad effect on Chinese agriculture, according to a new study. The so-called Bt cotton plants that produce a chemical that kills the cotton bollworm have not only reduced the incidence of the pest in cotton fields, but also in neighboring fields of corn, soybeans, and other crops. The study, published in the journal Science [subscription required], found that the altered cotton plants kill the bollworm larvae before they can mature and move on to other crops.

The cotton bollworm, Helicoverpa armigera, is one of the most serious insect pests in Asia, attacking wheat, corn, soya beans, peanuts and vegetables as well as cotton. In the early 1990s, repeated bollworm outbreaks in China were barely contained. The heavy pesticide use that controlled them killed thousands of people each year, according to [biotechnology researcher] Huang Dafang [Nature News], as many farmers didn’t wear protective gear while they drenched their crops with chemicals.

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The Food and Drug Administration proposed rules today to regulate genetically engineered animals that are raised for food or to produce medications. The agency would use its existing authority over animal drugs to regulate genetic engineering, the addition of genes to animals to improve food quality, build disease resistance or produce medicines for humans, the FDA said in a statement. Producers would have to demonstrate that altered animals, if intended for use as food, are safe to eat [Bloomberg].

The step is being viewed as yet another official vote of confidence in the safety of genetically engineered food products. Genetic engineering is already widely used in plants in the United States, where several government agencies oversee its use in agriculture. Crops like corn, cotton, and soybeans have been altered to be more resistant to pests or to endure high doses of weed-killers (like Monsanto’s blockbuster Roundup Ready crops). The FDA has previously said that cloned animals and their offspring are safe to eat and don’t require regulation, although squeamish consumers may put a damper on that market. It remains to be seen if consumers will accept genetically engineered steak and eggs.

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A new batch of genetically engineered bacteria may be able to slash the cost of producing ethanol from tough materials like wood chips and switchgrass, pushing the young ethanol industry closer to its goal of creating commercially competitive alternative fuel from the waste products of farming and forestry. Ethanol from cellulose, the kind of sugar in the likes of cornstalks and sawdust, is being promoted as an environmentally friendly alternative to fossil fuels, with the advantage that it does not use food crops such as corn as raw materials [Reuters].

Ethanol from corn and sugarcane is relatively easy to produce, because yeast convert the readily accessible sugars and starches into ethanol. Cellulose presents a stiffer challenge. Cellulose fibers contain longer polysaccharide chains than those found in starches and surround them with lignin and hemicelluose, which hold the fibers together and provide strength. This makes them tough—tough enough to hold up a tree—but it also makes the sugars within very hard to access [Ars Technica].

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Meat and milk from the offspring of cloned animals may already be part of the U.S. food supply, the Food and Drug Administration announced this week. While the cloning process is too expensive (about $20,000 per animal) to justify creating clones that will be turned into hamburgers, some ranchers have cloned animals with desirable traits, which they then breed the old-fashioned way to create offspring. Officials said it is impossible to differentiate between cloned animals, their offspring and conventionally bred animals, making it difficult to know if offspring are in the food supply [Reuters].

The use of cloned livestock–particularly cows, swine, and sheep–has been fiercely debated in the United States and Europe. In January, the FDA declared that cloned animals and their offspring were as safe to eat as conventionally bred animals; regulators still ask that food companies follow a voluntary moratorium on using cloned animals for food production, but no such moratorium exists for the clones’ natural offspring. Those offspring may have made it into the food supply, a U.S. Agriculture Department spokesman said, but “they would be a very limited number because of the very few number of clones that are out there and relatively few of those clones are at an age where they would be parenting” [Reuters].

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When a hummingbird or a hawk moth sups on the sweet nectar of a wild tobacco plant, they’re not just getting a tasty meal in exchange for their services in spreading the plant’s pollen. Instead, a new study shows that the nectar may be a complex chemical cocktail that simultaneously attracts and repels pollinators in order to optimize the amount of time they spend at each flower, and the attention they pay to flowers on different plants. “This paper shows just how sophisticated a plant can be in using chemistry to get what it wants,” [The Scientist] says lead researcher Ian Baldwin.

The researchers had already analyzed the chemical composition of tobacco plants’ nectar; they found that the compound benzyl acetone is the primary attractant, and that the plants “spike” their nectar with nicotine, presumably as a poisonous deterrent to insects. But in a clever experiment, the research team created genetically modified plants with different levels of these two chemicals. In greenhouse and field experiments, the scientists were surprised to find that not only did nicotine deter nectar robbers and plant nibblers, but the right dose prevented pollinators from lingering too long at any one flower, increasing the number of flowers visited [Science News].

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Scientists have produced the cells that make up delicate inner ear hairs in mouse embryos, a step that could point the way to reversing hearing loss and curing congenital deafness. Sensory hair cells inside the cochlea, the auditory portion of the inner ear, convert sound waves into electrical impulses that are delivered to the brain. The loss of these minute hairs, or the nerves that control them, is the most common cause of hearing impairment and so-called nerve deafness [ABC Science].

Researchers used gene therapy to create the crucial cells: They used a virus to introduce a gene into the mice embryos, which caused non-sensory cells to turn into cochlear hair cells. While this preliminary experiment was done on normal-hearing mice, the discovery that the engineered cochlear cells functioned as well as natural cells was an important step. Says lead researcher John Brigande: “One approach to restore auditory function is to replace defective cells with healthy new cells…. Our work shows that it is possible to produce functional auditory hair cells in the mammalian cochlea” [Reuters].

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