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Genetic Linkage

Designing a Better Probiotic. CRISPR Hubris?

Every morning I pop a Pearl probiotic. I try hard not to drop it, for the tiny, slippery yellow sphere bounces, is impossible to pick up, and cats love to bat them into unreachable domains.


A probiotic is, technically speaking, a population of live microorganisms that confers health benefits on the multicellular organism that they inhabit – such as a human. Probiotics alter the bacterial, viral, and fungal milieu within and on us – our microbiomes – in ways that ease digestion, counter inflammation, strengthen the gut lining, affect brain function, and even squelch tumors.


Each Pearl – or other variation on the probiotic theme – delivers billions of Lactobacilli to the twists and turns, nooks and crannies, of the human host's intestines, maintaining the microbial community within and keeping digestion flowing along smoothly. Other commonly used probiotics are Bifidobacterium and the yeasts Saccharomyces cerevisiae and boulardii.


Borrowed from Bacteria


To continue reading, go to DNA Science, where this post first appeared.

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Transmissible Alzheimer’s Disease? Long-Ago Growth Hormone Treatment and a Legacy of Cannibalism and Mad Cows

A stylized slice through an Alzheimer's brain depicts amyloid-beta plaques in brown and tau tangles in blue.

Five people treated for pituitary dwarfism decades ago with human growth hormone (hGH) pooled from cadavers have shown cognitive decline reminiscent of early-onset Alzheimer's disease. Their dementia likely arose from transmission of the bits of amyloid-beta protein that lie behind Alzheimer's delivered along with the needed hormone, initiating a molecular chain reaction that led to brain effects decades later. Recombinant DNA technology has since provided a pure source of the hormone.


The cognition decline in these people is iatrogenic – caused by a medical procedure. The pooled hGH included infectious proteins, called prions (pronounced "pree-ons"), short for "proteinaceous infectious agent." The research appears in Nature Medicine from long-time prion researcher John Collinge, director of the University College London Institute of Prion Diseases, and colleagues.


The team followed 8 patients. Two of the five with clinical signs of Alzheimer's died during the investigation, and autopsy revealed the telltale brain changes. Two other patients had mild cognitive impairment, and the eighth had no symptoms. None had mutations that cause Alzheimer's disease, ruling out genetics as a cause.


To continue reading, go to DNA Science, where this post first appeared.




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Chewing Gum Reveals Stone Age Diet and Disease

Did Barney Rubble and Fred Flinstone chew gum?


We can learn about life, past and present, anywhere we find DNA and determine its sequence. DNA Science has described intriguing sources of environmental DNA, aka eDNA: DNA in Strange Places: Hippo Poop, Zoo Air, and Cave Dirt and A Glimpse of the Ocean's Twilight Zone Through Environmental DNA.  


Human remains also harbor bits of DNA that can reveal how people lived long ago.


A recent report in PLOS ONE analyzes DNA from an adenovirus and a herpes virus discovered in preserved feces – coprolites – from 5,500 to 7,000 years ago at an archaeological site in Japan. The findings suggest that those people might have suffered from similar infections to humans today.


A second recent report uncovers clues in preserved chewing gum, reminding me of Flintstones gummy vitamins. (See A Brief History of Flintstones Vitamins). 


About 9,700 years ago, a group of teens were hunting, gathering, and fishing along the western coast of Scandinavia, north of what is today Göteborg. They chewed a concoction of hardened birch tar, the preserved lumps bearing bitemarks that suggest the stuff was used as a chewing gum of sorts, perhaps also as an adhesive in construction. An international research team published their findings on the Mesolithic gum in Scientific Reports.


To continue reading, go to DNA Science, where this post first appeared. 

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