Tag: dna

Thawing Diseases

In August 2016, in a remote corner of Siberian tundra called the Yamal Peninsula in the Arctic Circle, a 12-year-old boy died and at least 20 people were hospitalized after being infected by anthrax. The theory is that, over 75 years ago, a reindeer infected with anthrax died and it’s frozen carcass became trapped under a layer of frozen soil, known as permafrost. There it stayed until a heatwave in the summer of 2016, when the permafrost thawed.

Removing mutated mtDNA

The team developed a technique to remove mutated DNA from mitochondria, the small organelles that produce most of the chemical energy within a cell. There are 100s to 1000s of mitochondria per cell, each of which carries its own small circular DNA genome, called mtDNA, the products of which are required for energy production. Because mtDNA has limited repair abilities, normal and mutant versions of mtDNA are often found in the same cell, a condition known as heteroplasmy. Most people start off life with some level of heteroplasmy, and the levels of mutant mtDNA increase throughout life. When a critical threshold level of mutant mtDNA is passed, cells become nonfunctional or die.

Chromatin Loops

“It’s quite spectacular that the structure of an entire chromosome would rely on a small DNA sequence somewhere in the middle”. Scientists have long suspected that abnormal genome folding may cause diseases, and several new studies have identified links between genome architecture and biological development. A rearrangement of DNA in a noncoding region of the genome causes limb malformations during development by changing chromatin folding. Other researchers are using CRISPR to investigate whether changes to genome architecture affects the ability of parasites like Trypanosoma, the cause of African sleeping sickness, to evade the immune system. It’s becoming apparent that in the genome, “nothing makes sense except in 3D.”

The Lazarus File

In 1986, a young nurse named Sherri Rasmussen was murdered in Los Angeles. Police pinned down no suspects, and the case gradually went cold. It took 23 years—and revolutionary breakthroughs in forensic science—before LAPD detectives could finally assemble the pieces of the puzzle. When they did, they found themselves facing one of the unlikeliest murder suspects in the city’s history. When Lazarus arrived in the interrogation room, Stearns and Jaramillo abandoned the story of a suspect talking about stolen art, and explained that her name had come up in a case involving an ex-boyfriend of hers, John Ruetten. Knowing she was married to someone else, they’d selected a place where they could speak privately, away from gossiping colleagues. Stearns and Jaramillo interviewed Lazarus for more than 1 hour, coming at her in an oblique manner that left it unclear whether they were speaking with her as a possible witness or a criminal suspect. The conversation meandered, but every digression led back, inevitably, to the murder of Sherri Rasmussen. It was only after Jaramillo asked Lazarus if she’d be willing to give them a DNA swab and noted, “It’s possible we may have some DNA at the location,” that she wanted to contact a lawyer. Declaring herself “shocked,” the veteran detective stood and walked out, 68 minutes after she’d sat down. Lazarus got only as far as the jail’s hallway, where she was stopped by other RHD detectives and placed in handcuffs.

Gene drives

knowing what gene drives are is crucial to understand the most important and powerful biotechnology yet.

Gene drives work in mice:

In a paper in Nature, biologists demonstrate that gene drive technology also works — at least up to a point — in a mammal: the mouse. Their findings highlight the potential, but also the significant limitations, of putting gene drives to work in the real world. For at least some time to come, these kinds of “active genetics” technologies may be more useful as laboratory tools than as instruments for remaking nature.

Evolutionary Biochemistry

Bloom and others are part of a growing group of scientists who practice “evolutionary biochemistry.” They seek to explain life’s tremendous diversity and determine exactly how that diversity emerged. Rather than focusing on how plants or animals adapted to different environments, however, these researchers consider diversity on a much smaller scale: Their work aims to explain how the small set of proteins that powered primitive life-forms evolved into the millions of specialized proteins that drive biological processes today.

Exploiting the genetic records, Bloom can assemble virus proteins that existed in bygone times, then reconstruct how they evolved, 1 amino acid at a time. Other researchers are analyzing modern species to resurrect the ancestral forms of biological molecules that have evolved over millions of years.

Searching for Hannibal

this is insane:

they were scouting for a spot that could have been a watering hole during Hannibal’s era. they found a layer of “churned” soil they call the MAD, for “mass animal deposition”—a euphemism for dung. they discovered genetic material from several types of bacteria, including a high concentration of DNA fragments from Clostridia, which is frequently found in feces. Clostridia are pervasive in soil as well, but the team also detected fatty compounds that come from the gut. That combination is what they would expect to see in a place where a great number—100s if not 1000s—of mammals had defecated.