PRESS-NEWS.org - Press Release Distribution
PRESS RELEASES DISTRIBUTION

Gut microbes browse along a gene buffet

Collaboration between the host and microbes of the gut is finely tuned

2014-08-07
(Press-News.org) DURHAM, N.C. -- In the moist, dark microbial rainforest of the intestine, hundreds of species of microorganisms interact with each other and with the cells of the host animal to get the resources they need to survive and thrive.

Though there's a lot of competition in this vibrant ecosystem, collaboration is valued too. A new study on the crosstalk between microbes and cells lining the gut of mice shows just how cooperative this environment can be.

One of the main ways that hosts manage their interactions with microbes is by carefully controlling the genes that their cells use. Duke University researchers, with colleagues from UNC-Chapel Hill and Stanford, found that the host genes in the intestine are poised to respond to microbes, and the microbes signal to the host to determine which genes respond. The study appears August 7 in the journal Genome Research.

"The intestine has a tough assignment – it has to allow for digestion and absorption of dietary nutrients while also carefully harboring and managing the teeming microbial community within," said John Rawls, an associate professor of molecular genetics and microbiology in the Duke School of Medicine.

"These physiologic responsibilities and microbial interactions vary at different places along the gut." Molecules produced on demand by the host's genes have lots of different jobs that might help or hurt the bugs: immune responses, digestive enzymes, physiological "climate control" and metabolism, among others. In some cases, the microbes might even be calling in immune system attacks on their competitors, Rawls said. "Good fences make good neighbors."

Scientists have known for some time that different genes of the host are active (or expressed) at different stretches along the length of the gut, which is about 25 feet in humans. But how those genes interact with the microbial community hasn't been clear.

Every cell contains the complete set of DNA in the human genome, but most of it is tightly spooled away in storage and unavailable for expression. Depending on the tissue type and what jobs that tissue is doing, distinct portions of DNA are unspooled to become available for activity through a structure called open chromatin, said Gregory Crawford, an associate professor of pediatrics and expert on gene expression. These open chromatin regions are known to be key locations in the genome that control which genes are expressed and which aren't.

The researchers went into this study expecting to find that the microbes signaled the host to open up areas of chromatin to activate gene expression in the gut. But what they found is that the host chooses which chromatin regions are opened to make genes available for use in each region of the intestine.

Three different mouse populations were used for the study: mice that were raised germ-free, mice that started germ-free for 8-10 weeks but then got an intensive two-week colonization with microbes, and conventionally-raised mice exposed to whatever microbes were available in their environment.

Rather than finding three different patterns of open chromatin however, the experiments found that all three were pretty much the same. Their microbial exposures varied and gene expression patterns varied, but the parts of the genome that were open at each location in the gut remained consistent, Crawford said.

"In other words, access to the genes is determined by the host, but usage of particular genes is regulated by the microbes," Crawford said.

The current study just looked at cells of the epithelium, the layer of cells lining the gut, but there would be other cells responding to these microbial signals as well. "It's likely that these microbial signals reach other cells throughout the body, which in turn mount their own specific responses," Rawls said.

Rawls said many genes that are activated by microbes in the mouse gut are similarly responsive in the fish gut. "These are presumably very ancient modes of communication between the microbes and their animal hosts," Rawls said. "Microbes shape our health profoundly, but we're only starting to understand how they do it."

Having established some understanding of the open chromatin landscape in healthy mice, the researchers now hope to figure out how these relationships change with disease states.

INFORMATION: This research was supported by the National Institutes of Health (P30-DK034987, P40-OD010995, R01-DK081426, R01-HD059862, P01-DK094779), the National Science Foundation (DGE-1147470), the PhRMA Foundation and the Pew Scholars in the Biomedical Sciences Program.

CITATION: "Microbiota modulate transcription in the intestinal epithelium without remodeling the accessible chromatin landscape," J. Gray Camp, Christopher Frank, Colin Lickwar, Harendra Guturu, Tomas Rube, Aaron Wenger, Jenny Chen, Gill Bejerano, Gregory Crawford, John Rawls. Genome Research, Sept. 2014. DOI: 10.1101/gr.165845.113


ELSE PRESS RELEASES FROM THIS DATE:

NASA sees Hurricane Julio organize and emit a gamma-ray flash

NASA sees Hurricane Julio organize and emit a gamma-ray flash
2014-08-07
NASA's Fermi and Aqua satellites captured two different views of bursts of strength show by Hurricane Julio as it intensified. NASA's Fermi satellite saw a gamma-ray flash from Julio, while NASA's Aqua satellite saw Julio become more structurally organized as a hurricane. This type of outburst is known as a terrestrial gamma-ray flash (TGF). Produced by the powerful electric fields in thunderstorms, TGFs last only a few thousandths of a second but emit gamma rays that make up the highest-energy naturally-occurring light on Earth. Scientists estimate that, on average, ...

Wild sheep show benefits of putting up with parasites

Wild sheep show benefits of putting up with parasites
2014-08-07
In the first evidence that natural selection favors an individual's infection tolerance, researchers from Princeton University and the University of Edinburgh have found that an animal's ability to endure an internal parasite strongly influences its reproductive success. Reported in the journal PLoS Biology, the finding could provide the groundwork for boosting the resilience of humans and livestock to infection. The researchers used 25 years of data on a population of wild sheep living on an island in northwest Scotland to assess the evolutionary importance of infection ...

NASA sees Genevieve cross international date line as a Super-Typhoon

NASA sees Genevieve cross international date line as a Super-Typhoon
2014-08-07
Tropical Storm Genevieve had ups and downs in the Eastern Pacific and Central Pacific over the last week but once the storm crossed the International Dateline in the Pacific, it rapidly intensified into a Super Typhoon. NASA-NOAA's Suomi NPP satellite captured of the storm. When Suomi NPP flew over Genevieve on August 7 at 01:48 UTC the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument aboard captured an infrared image of the storm. VIIRS collects visible and infrared imagery and global observations of land, atmosphere, cryosphere and oceans. VIIRS flies aboard ...

Dramatic growth of grafted stem cells in rat spinal cord injuries

Dramatic growth of grafted stem cells in rat spinal cord injuries
2014-08-07
Building upon previous research, scientists at the University of California, San Diego School of Medicine and Veteran's Affairs San Diego Healthcare System report that neurons derived from human induced pluripotent stem cells (iPSC) and grafted into rats after a spinal cord injury produced cells with tens of thousands of axons extending virtually the entire length of the animals' central nervous system. Writing in the August 7 early online edition of Neuron, lead scientist Paul Lu, PhD, of the UC San Diego Department of Neurosciences and colleagues said the human iPSC-derived ...

Human skin cells reprogrammed as neurons regrow in rats with spinal cord injuries

2014-08-07
While neurons normally fail to regenerate after spinal cord injuries, neurons formed from human induced pluripotent stem cells (iPSCs) that were grafted into rats with such injuries displayed remarkable growth throughout the length of the animals' central nervous system. What's more, the iPSCs were derived from skin cells taken from an 86-year-old man. The results, described in the Cell Press journal Neuron, could open up new possibilities in stimulating neuron growth in humans with spinal cord injuries "These findings indicate that intrinsic neuronal mechanisms readily ...

Cancer study reveals powerful new system for classifying tumors

2014-08-07
Cancers are classified primarily on the basis of where in the body the disease originates, as in lung cancer or breast cancer. According to a new study, however, one in ten cancer patients would be classified differently using a new classification system based on molecular subtypes instead of the current tissue-of-origin system. This reclassification could lead to different therapeutic options for those patients, scientists reported in a paper published August 7 in Cell. "It's only ten percent that were classified differently, but it matters a lot if you're one of those ...

Largest cancer genomic study proposes 'disruptive' new system to reclassify tumors

2014-08-07
Novato, California: Researchers with The Cancer Genome Atlas (TCGA) have analyzed more than 3500 tumors on multiple genomic technology platforms, revealing a new approach to classifying cancers. This largest-of-its-kind study, published online August 7th in Cell featured major contributions by Buck faculty Christopher Benz, MD and Senior Staff Scientist Christina Yau, PhD. TCGA scientists analyzed the DNA, RNA and protein from 12 different tumor types using six different TCGA "platform technologies" to see how the different tumor types compare to each other. The study ...

University of Minnesota research finds key piece to cancer cell survival puzzle

2014-08-07
An international team led by Eric A. Hendrickson of the University of Minnesota and Duncan Baird of Cardiff University has solved a key mystery in cancer research: What allows some malignant cells to circumvent the normal process of cell death that occurs when chromosomes get too old to maintain themselves properly? Researchers have long known that chromosomal defects that occur as cells repeatedly divide over time are linked to the onset of cancer. Now, Hendrickson, Baird and colleagues have identified a specific gene that human cells require in order to survive these ...

Notch developmental pathway regulates fear memory formation

2014-08-07
Nature is thrifty. The same signals that embryonic cells use to decide whether to become nerves, skin or bone come into play again when adult animals are learning whether to become afraid. Researchers at Yerkes National Primate Research Center, Emory University, have learned that the molecule Notch, critical in many processes during embryonic development, is also involved in fear memory formation. Understanding fear memory formation is critical to developing more effective treatments and preventions for anxiety disorders such as post-traumatic stress disorder (PTSD). The ...

Scientists uncover stem cell behavior of human bowel for the first time

2014-08-07
For the first time, scientists have uncovered new information on how stem cells in the human bowel behave, revealing vital clues about the earliest stages in bowel cancer development and how we may begin to prevent it. The study, led by Queen May University of London (QMUL) and published today in the journal Cell Reports, discovered how many stem cells exist within the human bowel and how they behave and evolve over time. It was revealed that within a healthy bowel, stem cells are in constant competition with each other for survival and only a certain number of stem ...

LAST 30 PRESS RELEASES:

Pink skies

Monkeys are world’s best yodellers - new research

Key differences between visual- and memory-led Alzheimer’s discovered

% weight loss targets in obesity management – is this the wrong objective?

An app can change how you see yourself at work

NYC speed cameras take six months to change driver behavior, effects vary by neighborhood, new study reveals

New research shows that propaganda is on the rise in China

Even the richest Americans face shorter lifespans than their European counterparts, study finds

Novel genes linked to rare childhood diarrhea

New computer model reveals how Bronze Age Scandinavians could have crossed the sea

Novel point-of-care technology delivers accurate HIV results in minutes

Researchers reveal key brain differences to explain why Ritalin helps improve focus in some more than others

Study finds nearly five-fold increase in hospitalizations for common cause of stroke

Study reveals how alcohol abuse damages cognition

Medicinal cannabis is linked to long-term benefits in health-related quality of life

Microplastics detected in cat placentas and fetuses during early pregnancy

Ancient amphibians as big as alligators died in mass mortality event in Triassic Wyoming

Scientists uncover the first clear evidence of air sacs in the fossilized bones of alvarezsaurian dinosaurs: the "hollow bones" which help modern day birds to fly

Alcohol makes male flies sexy

TB patients globally often incur "catastrophic costs" of up to $11,329 USD, despite many countries offering free treatment, with predominant drivers of cost being hospitalization and loss of income

Study links teen girls’ screen time to sleep disruptions and depression

Scientists unveil starfish-inspired wearable tech for heart monitoring

Footprints reveal prehistoric Scottish lagoons were stomping grounds for giant Jurassic dinosaurs

AI effectively predicts dementia risk in American Indian/Alaska Native elders

First guideline on newborn screening for cystic fibrosis calls for changes in practice to improve outcomes

Existing international law can help secure peace and security in outer space, study shows

Pinning down the process of West Nile virus transmission

UTA-backed research tackles health challenges across ages

In pancreatic cancer, a race against time

Targeting FGFR2 may prevent or delay some KRAS-mutated pancreatic cancers

[Press-News.org] Gut microbes browse along a gene buffet
Collaboration between the host and microbes of the gut is finely tuned