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Researchers Develop "Species from Feces" DNA Tool to Identify Bats

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Animal poop is an underappreciated resource for studying shy animals, a new study argues. Published today, September 21, in PLOS One, the research by bat ecologists and geneticists at Northern Arizona University finds that guano can be used to identify different species when the bats themselves aren’t present.

“Bat guano is a relatively untapped reservoir of information,” they write. To mine it, the researchers developed the memorably named Species From Feces, a DNA mini-barcoding tool that can confirm the species of bats present in different environments or confirm the species of captured bats that are hard to identify by eye. It analyzes a certain mitochondrial gene present in bats all over the world, but not in their prey. That makes it ideal to target in a feces test, where there might be remnants of the bat’s dinner as well as its own genetic material.

This study validated the test by using it to correctly identify 54 different bat species from eight families. It was correct 92 percent of the time when identifying species from a larger research database containing the genetic information of about a third of the world’s known bats (1338 species).

The test works with both fresh guano or older pellets, and can identify both those bats that eat insects and those that feed on nectar, individually and in larger communities. The project has a searchable database where other researchers can confirm that the test works for the species they’re looking to study. Need your bat guano tested? See the lab's brochure of services [PDF].

This feces-based technique could be useful in studying bat diseases like the deadly White Nose Syndrome, a fungal disease that has killed millions of North American bats.

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Why DNA Is So Hard to Visualize
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Picture a strand of DNA and the image you see will likely be similar to the artist’s rendering above. The iconic twisted ladder, or double-helix structure, was first revealed in a photo captured by Rosalind Franklin in the 1950s, but this popular visualization only tells part of the story of DNA. In the video below, It’s Okay to Be Smart explains a more accurate way to imagine the blueprints of life.

Even with sophisticated lab equipment, DNA isn’t easy to study. That’s because a strand of the stuff is just 2 nanometers wide, which is smaller than a wavelength of light. Researchers can use electron microscopes to observe the genetic material or x-rays like Rosalind Franklin did, but even these tools paint a flawed picture. The best method scientists have come up with to visualize DNA as it exists inside our cells is computer modeling.

By rendering a 3D image of a genome on a computer, we can see that DNA isn’t just a bunch of free-floating squiggles. Most of the time the strands sit tightly wound in a well-organized web inside the nucleus. These balls of genes are efficient, packing 2 meters of DNA into a space just 10 millionths of a meter across. So if you ever see a giant sculpture inspired by an elegant double-helix structure, imagine it folded into a space smaller than a shoe box to get closer to the truth.

[h/t It’s Okay to Be Smart]

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Scientists Remove Disease-Causing Mutations from Human Embryos
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Researchers have successfully edited the genes of viable human embryos to repair mutations that cause a dangerous heart condition. The team published their controversial research in the journal Nature.

The versatile gene-editing technique known as CRISPR-Cas9 is no stranger to headlines. Scientists have already used it to breed tiny pigs, detect disease, and even embed GIFs in bacteria. As our understanding of the process grows more advanced and sophisticated, many researchers have wondered how it could be applied to human beings.

For the new study, an international team of researchers fertilized healthy human eggs with sperm from men with a disease called hypertrophic cardiomyopathy, a condition that can lead to sudden death in young people. The mutation responsible for the disease affects a gene called MYBPC3. It’s a dominant mutation, which means that an embryo only needs one bad copy of the gene to develop the disease.

Or, considered another way, this means that scientists could theoretically remove the disease by fixing that one bad copy.

Eighteen hours after fertilizing the eggs, the researchers went back in and used CRISPR-Cas9 to snip out mutated MYBPC3 genes in some of the embryos and replace them with healthy copies. Three days later, they checked back in to see how their subjects—which were, at this point, still microscopic balls of cells—had fared.

The treatment seemed successful. Compared to subjects in the control group, a significant number of edited embryos appeared mutation- and disease-free. The researchers also found no evidence that their intervention had led to any unwanted new mutations, although it is possible that the mutations were there and overlooked.

Our ability to edit human genes is improving by the day. But, many ethicists argue, just because we can do it doesn’t mean that we should. The United States currently prohibits germline editing of human embryos by government-funded researchers. But there’s no law against such experimentation in privately funded projects like this one.

The same day the new study was published, an international committee of genetics experts issued a consensus statement advising against editing any embryo intended for implantation (pregnancy and birth).

"While germline genome editing could theoretically be used to prevent a child being born with a genetic disease, its potential use also raises a multitude of scientific, ethical, and policy questions,” Derek T. Scholes of the American Society of Human Genetics said in a statement. “These questions cannot all be answered by scientists alone, but also need to be debated by society."

Ethicists and sociologists are concerned by the slippery slope of trying to build a better human. Many people with chronic illness and disability live happy, complete lives and report that they’re limited more by discrimination than by any medical issues.

Disability studies expert Lennard Davis of the University of Illinois says we can’t separate scientific decisions from our society’s history of violence against, and oppression of, disabled and sick people.

“A lot of this terrific science and technology has to take into account that the assumption of what life is like for people who are different is based on prejudice against disability,” he told Nature in 2016.

Rosemary Garland-Thomson is co-director of the Disability Studies Initiative at Emory University. Speaking to Nature, she said we are at a cultural and ethical precipice: “At our peril, we are right now trying to decide what ways of being in the world ought to be eliminated.”

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