Category Archives: Life Science

Waste from Gut Bacteria Helps Host Control Weight

A single molecule in the intestinal wall, activated by the waste products from gut bacteria, plays a large role in controlling whether the host animals are lean or fatty, a research team, including scientists from UT Southwestern Medical Center, has found in a mouse study.

When activated, the molecule slows the movement of food through the intestine, allowing the animal to absorb more nutrients and thus gain weight. Without this signal, the animals weigh less.

The study shows that the host can use bacterial byproducts not only as a source of nutrients, but also as chemical signals to regulate body functions. It also points the way to a potential method of controlling weight, the researchers said.

“It’s quite possible that blocking this receptor molecule in the intestine might fight a certain kind of obesity by blocking absorption of energy from the gut,” said Dr. Masashi Yanagisawa, professor of molecular genetics at UT Southwestern and a senior co-author of the study, Proceedings of the National Academy of Sciences, open access: Effects of the gut microbiota on host adiposity are modulated by the short-chain fatty-acid binding G protein-coupled receptor, Gpr41.

Humans, like other animals, have a large and varied population of beneficial bacteria that live in the intestines. The bacteria break up large molecules that the host cannot digest. The host in turn absorbs many of the resulting small molecules for energy and nutrients.

In the Big Fat Lie I mentioned some related ideas:

It also makes perfect sense that our bodies evolved to store energy for worse times (and some of us have bodies better at doing that). Now we are in a new environment where (at least for many people alive today) finding enough calories is not going to be a problem so it would be nice if we could tell our bodies to get less efficient at storing fat

This research seems to be looking for a similar way to attack the obesity epidemic: reduce the efficiency of our bodies converting potential energy in the food we eat to energy we use or store. If we can make that part of the solution that will be nice. So far the reduction in our activity and increase in food intake have not been getting good results. And efforts to increase (from our current low levels) activity and reduce food intake have not been very effective.
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Plants can Signal Microbial Friends for Help

When under attack, plants can signal microbial friends for help

Researchers at the University of Delaware have discovered that when the leaf of a plant is under attack by a pathogen, it can send out an S.O.S. to the roots for help, and the roots will respond by secreting an acid that brings beneficial bacteria to the rescue.
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In a series of laboratory experiments, the scientists infected the leaves of the small flowering plant Arabidopsis thaliana with a pathogenic bacterium, Pseudomonas syringae. Within a few days, the leaves of the infected plants began yellowing and showing other symptoms of disease.

However, the infected plants whose roots had been inoculated with the beneficial microbe Bacillus subtilis were perfectly healthy. Farmers often add B. subtilis to the soil to boost plant immunity. It forms a protective biofilm around plant roots and also has antimicrobial properties, according to Bais.

Using molecular biological tools, the scientists detected the transmission of a long-distance signal, a “call for help,” from the leaves to the roots in the plants that had Bacillus in the soil. The roots responded by secreting a carbon-rich chemical–malic acid.

All plants biosynthesize malic acid, Bais explains, but only under specific conditions and for a specific purpose–in this case, the chemical was actively secreted to attract Bacillus. Magnified images of the roots and leaves showed the ratcheted-up defense response provided by the beneficial microorganisms.
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“Plants can’t move from where they are, so the only way they can accrue good neighbors is through chemistry,” Bais notes.

Virgin Birth for Another Shark Species

Virgin shark birth in Virginia

The first time it happened, scientists thought it might be a fluke. A female hammerhead shark residing at a zoo in Omaha, Neb., had not been in contact with male sharks for at least three years and yet experienced a “virgin birth.” She delivered a single pup.

But it has happened again, according to today’s issue of the Journal of Fish Biology. This time, a blacktip shark… had spent nearly her entire eight years at either the Virginia Aquarium without any male companionship from her kind.

Keeping Invassive Plants Out of Your Garden

Tending the Garden, Sparing the Ecosystem

The plants and animals that naturally exist in a place evolved together, adapted together and coexist for mutual benefit. Birds, insects and other animals help pollinate plants and distribute seeds. Plants provide food and shelter for the animals.

When you start adding exotic or nonnative species, or subtracting native species, you disrupt the balance. Native creatures may not be able to get nourishment from nonnative plants, and indigenous plants may not be able to compete with invasive alien plants.
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The native plant society strongly recommends physical methods for getting rid of plants, as opposed to using herbicides. But where plant stands are large or hard to control by clipping or pulling, chemicals may well be the last resort.

The Nobel Prize in Chemistry 2008

The Nobel Prize in Chemistry 2008 is evenly shared by Osamu Shimomura, Boston University Medical School, USA; Martin Chalfie, Columbia University, New York, USA and Roger Y. Tsien, University of California, San Diego, USA for discovery and work with glowing green fluorescent protein.

The remarkable brightly glowing green fluorescent protein, GFP, was first observed in the beautiful jellyfish, Aequorea victoria in 1962. Since then, this protein has become one of the most important tools used in contemporary bioscience. With the aid of GFP, researchers have developed ways to watch processes that were previously invisible, such as the development of nerve cells in the brain or how cancer cells spread.

Tens of thousands of different proteins reside in a living organism, controlling important chemical processes in minute detail. If this protein machinery malfunctions, illness and disease often follow. That is why it has been imperative for bioscience to map the role of different proteins in the body.

This year’s Nobel Prize in Chemistry rewards the initial discovery of GFP and a series of important developments which have led to its use as a tagging tool in bioscience. By using DNA technology, researchers can now connect GFP to other interesting, but otherwise invisible, proteins. This glowing marker allows them to watch the movements, positions and interactions of the tagged proteins.

Researchers can also follow the fate of various cells with the help of GFP: nerve cell damage during Alzheimer’s disease or how insulin-producing beta cells are created in the pancreas of a growing embryo. In one spectacular experiment, researchers succeeded in tagging different nerve cells in the brain of a mouse with a kaleidoscope of colors.

Osamu Shimomura, a Japanese citizen, was born 1928 in Kyoto, Japan. He received his Ph.D. in organic chemistry 1960 from Nagoya University, Japan. first isolated GFP from the jellyfish Aequorea victoria, which drifts with the currents off the west coast of North America. He discovered that this protein glowed bright green under ultraviolet light.

Martin Chalfie demonstrated the value of GFP as a luminous genetic tag for various biological phenomena. In one of his first experiments, he coloured six individual cells in the transparent roundworm Caenorhabditis elegans with the aid of GFP.

Roger Y. Tsien contributed to our general understanding of how GFP fluoresces. He also extended the colour palette beyond green allowing researchers to give various proteins and cells different colours. This enables scientists to follow several different biological processes at the same time.

Stanford Gets $75 Million for Stem Cell Center

Stanford gets $75 million for stem cell center

With today’s announcement, Lokey more than doubles his commitment. School officials say he is the lead contributor for a $200 million stem cell research building that will break ground Oct. 27 and be finished in the summer of 2010. In a statement released by the medical school, Lokey said stem cells would be “as significant as the silicon chip that created Silicon Valley,” producing treatments for disease and saving lives.

He said he was driven to fund research after President Bush, in August 2001, forbid the use of federal funds for stem cell research that involved the destruction of human embryos. “It’s very narrow-minded,” Lokey said of the position. “This is about lives being saved.”
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Some 350 scientists will work in the 200,000-square-foot Lorry I. Lokey Stem Cell Research Building, the school said. The center is also getting a $43.6 million grant from the California Institute for Regenerative Medicine. The institute, the state’s $3 billion stem cell funding unit, was created by a 2004 state initiative from research advocates opposed to Bush’s restrictions.

Nobel Prize in Physiology or Medicine 2008

photos of Harald zur Hausen, FranÃ§oise BarrÃ©-Sinoussi and Luc Montagnier

The Nobel Prize in Physiology or Medicine for 2008 with one half to Harald zur Hausen for his discovery of “human papilloma viruses causing cervical cancer” and the other half jointly to FranÃ§oise BarrÃ©-Sinoussi and Luc Montagnier for their discovery of “human immunodeficiency virus.”

Harald zur Hausen went against current dogma and postulated that oncogenic human papilloma virus (HPV) caused cervical cancer, the second most common cancer among women. He realized that HPV-DNA could exist in a non-productive state in the tumours, and should be detectable by specific searches for viral DNA. He found HPV to be a heterogeneous family of viruses. Only some HPV types cause cancer. His discovery has led to characterization of the natural history of HPV infection, an understanding of mechanisms of HPV-induced carcinogenesis and the development of prophylactic vaccines against HPV acquisition.

FranÃ§oise BarrÃ©-Sinoussi and Luc Montagnier discovered human immunodeficiency virus (HIV). Virus production was identified in lymphocytes from patients with enlarged lymph nodes in early stages of acquired immunodeficiency, and in blood from patients with late stage disease. They characterized this retrovirus as the first known human lentivirus based on its morphological, biochemical and immunological properties. HIV impaired the immune system because of massive virus replication and cell damage to lymphocytes. The discovery was one prerequisite for the current understanding of the biology of the disease and its antiretroviral treatment.

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MicroRNAs Emerged Early in Evolution

New Research Shows MicroRNAs Emerged Early in Evolution

“MicroRNAs have been available to regulate and shape gene expression as far back as we can go in animal evolution—they might even predate animals,” says Bartel, a leader in the discovery and functional study of microRNAs. “They might have helped to usher in the era of multi-cellular animal life.”

First discovered in 1993, microRNAs are strands of RNA that are 21-24 nucleotides in length. They dampen gene expression by intercepting messenger RNA before it can turn the cellular crank that translates a gene into a protein. Earlier, Bartel’s research team showed that each microRNA can regulate the expression of hundreds of genes.

The ability of microRNAs to silence gene expression likely evolved from a more ancient defense against viruses, bacteria, and other mobile genetic elements that can mutate host DNA.
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The scientists determined that the starlet sea anemone has both microRNAs and piRNAs. In addition, the anemone makes proteins resembling those that interact with these small RNAs in humans. Both types of small RNA were also found in the sponge. The third target of their search, Trichoplax, did not contain any microRNAs, though Bartel suspects they may have existed in ancestral forms and later disappeared.

$400 Million More for Harvard and MIT

$400 million endowment for the Broad Institute of Harvard and MIT

“Today the Broad Institute is the world’s leading genomics and biomedical institute, and we’re now making a $600 million bet that the Broad will be the place where the greatest scientific discoveries take place,” Eli Broad said at today’s ceremony.
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In its short history, the Broad Institute’s accomplishments include cataloging and identifying genetic risk factors for diseases such as type 2 diabetes and autism; discovering new therapeutic targets for cancer, malaria, and other diseases; and applying genomic tools to better understand and treat human pathogens like tuberculosis.
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The Broads’ gift is the largest to support biomedical research at a university anywhere in the world. The Broads initially invested $100 million in 2003 as a way to test the institute’s new approach to biomedical research. By 2005, the Broad Institute had already made significant accomplishments and progress, and the Broads invested a second $100 million. Their endowment of $400 million today will allow the Broad Institute to transition to a permanent, non-profit 501(c)(3) organization with both Harvard and MIT still at the heart of it, continuing to help govern the institute.

Many countries would love to create a world class center of biomedical research. And several are trying. Boston sure seems to be staking a claim that it will be one of those centers of excellence. The economic benefits of that to Boston will be huge.

Foreign Cells Outnumber Human Cells in Our Bodies

This is one of those area I find very interesting: People Have More Bacterial Cells than Human Cells. Colin Nickerson has written an interesting article on the topic: Of microbes and men

Scientists estimate that 90 percent of the cells contained in the human body belong to nonhuman organisms – mostly bacteria, but also a smattering of fungi and other eensy entities. Some 100 trillion microbes nestle in niches from our teeth to our toes.

But what’s setting science on its heels these days is not the boggling numbers of bugs so much as the budding recognition that they are much more than casual hitchhikers capable of causing disease. They may be so essential to well-being that humans couldn’t live without them.

In this emerging view, humans and their microbes – or, as some biologists playfully put it, microbes and their attached humans – have evolved together to form an extraordinarily complex ecosystem.

The understanding of the complex interaction is something I came to through reading on the overuse of antibiotics. And the more I read the more interesting it gets.

“We can’t take nutrition properly without bacteria. We can’t fight bad germs without good germs,” he said. “It may turn out that secretions from bacteria affect not only long-term health, but hour-by-hour moods – could a person’s happiness depend on his or her bugs? It’s possible. Our existences are so incredibly intertwined.”

However, in the opinion of some researchers, this strange union may be headed for trouble because of profligate use of antibiotics and antiseptic lifestyles that deter the transfer of vital strains of bacteria that have swarmed in our systems at least since early humans ventured out of Africa.