Micro Eclectics

One Shake Shack French fry may lead you to eat a whole batch, and don't even get started on the power of Doritos. According to a new study using rats, that high-fat indulgence literally changes the populations of bacteria residing inside the gut and also alters the signaling to the brain. The result? The brain no longer senses signals for fullness, which can cause overeating--a leading cause of obesity.  The findings presented this week at the Annual Meeting of the Society for the Study of Ingestive Behavior liken a high fat diet to how a sudden significant shift in temperature might impact the people who live in the affected area: Some people will be fine. Others will become ill. "When we switch the rats to a high fat diet, it reorganizes brain circuits," explained Krzysztof Czaja, DVM, PhD, a principal investigator on the study who is an associate professor of neuroanatomy at the University of Georgia College of Veterinary Medicine. "The brain is changed by e...

Television commercials assure us that probiotic products are good for our health, with claims ranging from improved digestion to managing allergies and colds, If so, why wouldn't plants also benefit from certain microbes? In plants, beneficial bacteria and fungi are endophytes. Scientists have known for decades that plants like legumes (peas, beans, and lentils) have beneficial bacteria in nodules attached to their roots. These bacteria "fix" vital nitrogen, turning it into a form the plant can easily use. However, researchers have recently found some nitrogen-fixing bacteria actually live inside plant tissue--in the leaves, stems, and roots--with impressive results. Sharon Doty, an associate professor at the University of Washington, was one of the first to discover these bacteria, and their successful transfer between plants. A comparison of rice plants grown without the endophyte (E-) and with the endophyte (E+). Photo by Hyungmin Doty and her team isolated e...

Given a critical change in the environment, how exactly do species adapt?  To find the answer you need controlled experiments and a variable. A team recently did just that to to get at the heart of this evolutionary question, by measuring the growth rates and DNA mutations of 8 different species of Pseudomona s bacteria.  They controlled a single but vital variable during growth, the dose of the antibacterial drug rifampicin, and challenged 480 populations from 8 different strains of Pseudomonas (3840 total) with adapting to the minimal concentration of rifampicin that is needed to completely inhibit the growth of the ancestral strain of each species. They carried out the experiment over 30 generations of bacteria.  Next, the researchers selected 75 randomly chosen rifampicin-resistant mutants from 8 different clonal bacterial strains and sequenced the rpoB gene in all 600 mutants, identifying 47 different mutations. They measured both the growth...

It's hard to have our steak and eat it too. Red meat was once implicated in a wave of studies and linked to heart disease and other maladies, before being absolved. But the microbiome and the surge in advertising for probiotics to promote 'healthy' gut bacteria has implicated red meat again - this time by correlating a nutrient that the authors say is changed by gut bacteria into an atherosclerosis-causing metabolite, which means hardening of the arteries. Writing in Cell Metabolism , Dr. Stanley Hazen, of the Cleveland Clinic and colleagues implicated a bacteria in the gut that converts L-carnitine, a nutrient abundant in red meat, into a compound called trimethylamine, which in turn changes to a metabolite named trimethylamine-N-oxide (TMAO), which promotes atherosclerosis. Now they believe another metabolite, called gamma-butyrobetaine, is generated to an even greater extent by gut bact...

The adult human body is made up of about 37 trillion cells. Microbes, mainly bacteria, outnumber body cells by 10 to 1. This huge community of microbes, called the microbiome, affects the health, development and evolution of all multicellular organisms, including humans, according to the latest craze in health supplement marketing and plenty of science papers latching onto the fad. Symbiotic microbes can help prevent infection by disease-causing pathogens but sometimes the interaction goes the other way, with a pathogen or disease disrupting the normal community of symbiotic bacteria. In a new paper in the Proceedings of the National Academy of Sciences , a team of scientists from UC Santa Barbara say that a fungal pathogen of amphibians does just that. Experiments with model organisms such as mice have shown that infectious pathogens can disrupt the "normal" microbiome, but the extent to which this p...

Archaea are a family of single-celled organisms that can thrive in environments like boiling hydrothermal pools and smoking deep sea vents deep underground, which are too extreme for most other species to survive. Until the late 1970s, biologists thought that Archaea were just weird bacteria, but then a landmark analysis of their DNA showed that they represent an independent branch on the tree of life that stretches back more than three billion years.  Now they may be a new source of antibacterial drugs.  Researchers have discovered a functional antibacterial gene in Archaea  The realization that Archaea could be a source of novel pharmaceuticals emerges from a study of widespread horizontal gene transfer between different species conducted by a team of scientists from Vanderbilt University and Portland State University in Oregon. The researchers were investigating a gene that produces a type of enzyme found in tears, saliva, milk and mucu...

Yeast cells can sometimes reverse the protein misfolding and clumping associated with diseases such as Alzheimer's, according to new research which contradicts the idea that once prion proteins have changed into the shape that aggregates, the change is irreversible. Prions are proteins that change into a shape that triggers their neighbors to change, also. In that new form, the proteins cluster. The aggregates, called amyloids, are associated with diseases including Alzheimer's, Huntington's and Parkinson's. For yeast, having clumps of amyloid is not fatal. In a new study, researchers exposed amyloid-containing cells of baker's yeast to 104 F (40 C), a temperature that would be a high fever in a human.  When exposed to that environment, the cells activated a stress response that changed the clumping proteins back to the no-clumping shape. The finding suggests artificially inducing stress responses may one day help develop treatments for diseas...