It's a microbial world

Biologists found a staggering 167,000 kinds of microbes living in the park’s soil – the vast majority of them never before documented.

And that’s just in the top two inches.

In a paper published on Wednesday, the researchers called Central Park’s dirt “a terra incognita in one of the most frequently visited urban parks in the world.”

DNA sequencing isolated the 167,000 different phylotypes (roughly equivalent to species) contained in the samples.

Climate change is prompting great migrations north for species big and small.

From a recent New York Times article, “As the planet warms, scientists say, the range of many plants and animals will change, shifting to cooler climes closer to the poles or at higher elevations. Such changes have already been documented for hundreds of species, including American goldfinches, brown argus butterflies and red oaks.”

An Arizona State microbiologist, Farran Garcia-Pichel, has located new evidence of microorganisms moving too. “This type of climate change impact may occur even among the smallest organisms. Photosynthesizing microbes that colonize arid soils will shift across the Southwest, with more heat-tolerant species moving northward and upward as temperatures increase.”

Molecular Origins Of Eating Disorders Found In Gut Microbe

The incidence of eating disorders (EDs) such as bulimia and anorexia nervosa somewhere between 5 to 10% of the population but there is very little understanding of the biological mechanism that is the source of the disease.  Given that mood disorders such as depression and schizophrenia have roots in biochemical imbalances, there is speculation that eating disorders can be traced to a similar cause. 

Now researchers at the French Institute of Health and Medical Research and the University of Rouen in France have found strong evidence that a protein made by intestinal bacteria are a causative agent for the disorders.  Specifically, antibodies made by the host against this protein cross-react with a mammalian satiety hormone.  The severity of symptoms in ED patients was also found to correlate with levels of the neutralizing antibodies.  The researchers believe that this understanding will ultimately lead to a chemical therapeutic strategies to correct eating disorders. 

The scientists focused on a known mammalian modulator of feeding behavior, the protein α-MSH, known variously as alpha-Melanocyte-stimulating hormone and alpha-melanotropin among other names.  α-MSH has been implicated in EDs.  Using a molecular “fishing” tool, they pulled from the common mammalian gut microbiome inhabitant E. coli K12 a “mimetic”, a protein that is very similar to human α-MSH, called ClpB.

Next, the researchers checked how a host responds to dosages of ClpB.  Mice which were dosed with ClpB indeed lost weight briefly but a month later increased their weight by 5%.  These mice remarkably also became immune to α-MSH, which usually induces anorexic-like effects.  In summary, these results show that ClpB provokes a feeding or energy usage reaction in the host that at early times looks like weight loss but at later times weight gain.

To understand the link between bacterial ClpB and host α-MSH, the researchers verified that administering ClpB in the mice provoked an immune reaction not only to ClpB itself, but to the similar protein α-MSH.  This means that host produces antibodies to the bacteria that inadvertently hit its own α-MSH, a regulator of feeding, energy regulation and anxiety.

Finally, the researchers decided to challenge the mice directly with E. coli, rather than with the purified ClpB protein.  They split the mice into three groups.  The first group received a dose of regular strain E. coli K12, the second a mutant strain missing only the ClpB protein, and a third that received no bacteria.  As before, in the short term (first few days) the mice which received E. coli K12 showed weight loss but then recovery later.  Mice that received mutant E. coli K12 that was missing ClpB did not show any of these responses, much like the control mice.

“We are presently working to develop a blood test based on detection of the bacterial protein ClpB. If we are successful in this, we will be able to establish specific and individualised treatments for eating disorders,” said Professor Fetissov, the senior author.

Dr. Naouel Tennoune was the primary author.  The title of the publication is “Bacterial ClpB heat-shock protein, an antigen-mimetic of the anorexigenic peptide α-MSH, at the origin of eating disorders.”

How Will You Die?

So let’s cut to the chase. Depending on where you live on Earth, cooking dinner, having sex and going to the bathroom are either three of life’s many pleasures, or they’re the riskiest things you can do.

Why?

When you dig into global statistics, two interesting facts pop out. The first is that, from a scientific perspective, we all pretty much die the same way: lack of blood to the brain. But how we get to that last stage varies quite a bit. And in a global sense, it varies depending on where you live and how much money you make.

The World Bank says there are 213 countries (but the specific number depends on how you count). It divides them into three groups based on average income per person: high-, middle- and low-income countries.

Continue reading.

Which Contagious Diseases Are The Deadliest?

No one knows what the death toll in the Ebola epidemic will be. As of Tuesday, nearly 2,500 people have died and nearly 5,000 have caught the virus, the World Health Organization says.

So how does this epidemic compare with the toll taken by other contagious diseases?

Comparing fatality rates could help put the current Ebola outbreak in perspective. Trouble is, getting an accurate value for many diseases can be hard, especially in places where the health care infrastructure is weak.

Take the situation in West Africa right now. “We can only count those who come to the doctor, not those who stayed home and got well, or those who stayed home and died,” says Carol Sulis, an epidemiologist at Boston University School of Medicine and the Boston Medical Center.

Another issue is that “deadliest” can mean two things. It can refer to the fatality rate — the number of deaths per number of cases — or it can mean the number of deaths in total caused by a disease.

What’s more, diseases can take a different toll in different parts of the world. In low- and middle-income countries, only limited medical care may be available, if that. This will raise the fatality rate for many infectious diseases, such as tuberculosis, malaria and infectious diarrhea.

"Similar to Ebola, people’s chances of survival increase for most of these [contagious] diseases, some dramatically, if people receive medical treatment," says epidemiologist Derek Cummings, at the Johns Hopkins Bloomberg School of Public Health.

Even if lists have their limitations, they can shed light. We spoke to Cummings and Sulis and consulted data from the World Health Organization and the U.S. Centers for Disease Control and Prevention to come up with two lists: the deadliest contagious diseases by death toll and by death rate if untreated.

See the lists here.