AP Biology class blog for discussing current research in Biology

Author: sheasexual

Sometimes less is better. Especially in the case of germs.

Scanning electron micrograph of Escherichia coli

Photo by NIAID

Apparently we’re healthier than we thought!!

Throughout the 20th century, scientists who studied the microbiome had thought that humans contain around 9000 times more germs than human cells.  Scientists now believe, however, that that number is more like 30 percent.

Micro biologists: Ron Sender, Ron Milo, and Shai Fuchs took on the challenge to actually find out the ratio of bacteria to cells in the human body.  First, its important to know the types of cells that make up the human body.  One might think that muscle and fat cells make up the largest portion of human cells in the body but that is wildly incorrect.  In fact, despite their weight and size dominance, they make up a measly .2 percent of the body’s cells while blood cells make up 90 percent (mostly red blood cells).

The colon houses the most bacteria in the human body by a long shot.  This makes sense as it is the pathway for human feces out of the body and reaches up to 5 feet in length.  The “trio” of scientists estimate that the human body contains somewhere between 30 trillion and 50 trillion cells and that the bacterial count is around 30 to 60 percent higher than the amount of cells.

Now, despite the insightful findings of Sender, Milo, and Fuchs, the microbiome community still has a lot of research to do into the subject of germ:cell ratio in humans and scientists believe that the trio missed some important factors in their experiments and as geneticist Julie Segre points out, “Other researchers also point out that the new paper’s calculations focused on bacteria. Yet the body can host other types of microbes as well. Those include viruses, fungi and archaea (Ar-KEE-uh). Viruses tend to vastly outnumber bacteria, so they could skew the microbe-to-human cell ratio upwards.”

The most important and prevailing part of the trio’s research was that the amount of bacteria that we have in our body and attached to human cells is much less than we had previously believed.

Original Article 

Iceman had a lot of problems: Murdered and had a tummy bug

Oetzi_the_Iceman_Rekonstruktion_1 (Recreated model of Iceman)

Photo by Thilo Parg

Iceman reveals a frightening and revolutionary phenomena that suggests that previously considered ancient bacterial strains are much more recent than we had thought.  “Otzi the Iceman” is a mummy discovered in 1991 inside a glacier in the Tyrolean Alps of Italy.  Scientists have done more tests on Iceman’s body than on any known mummy in history but they have also found out a lot about him and human life during his time through stomach, bowel, tooth, skin, and just about any part of his remaining tissue.  For starters, scientific research has theorized that he was a farmer living in Europe over 5300 years ago when he was murdered and left for dead in the freezing Alps.  But Iceman never ceases to provide new scientific insight into human migration and behavior thousands of years ago as scientists have recently discovered an ancient strain of Helicobacter Pyori, a common strain of the stomach bug which is known to cause painful ulcers in the stomach, in Iceman’s gut tissue.

Hp (Helicobacter Pyori) is one of the most common bacterial genomes in existence today as it is found in different strains all over the world and “causes ulcers, cancer, and gastritis—the inflammation of the lining of the stomach—in about 10% of people,” says Ann Gibbons.  Scientists have separated the three main origins of the genome to three continents: Africa, Asia, and Europe, each with their own distinct strains of Hp.  The modern hpEurope strain is theorized to have shared “elements of DNA with types of H. pylori from both Africa and Asia” says Gibbons.  This would suggest an ancient collision of the two strains in one human being who than spread it to more and more people who then migrated to Europe.

Until recently, no one could test this theory.  Months ago, imaging conducted on Iceman’s stomach and gut suggested that his gut tissue and stomach contents were quite well preserved so scientists jumped right to testing them through multiple biopsies.  They discovered two things: he had a full stomach (before he died he stuffed down a bunch of ibex meat) and that he inhabited an strain of hp traced to India and South Asia.  This tells us that “The ancestors of early European farmers such as Ötzi must have carried H. pylori with DNA from Asian strains perhaps in the Middle East before they migrated to Europe. Then, new immigrants carrying African microbes arrived in Europe much later, after Ötzi lived. The two types of microbes mixed in these migrants,creating today’s European strain much more recently than expected” according to Gibbons.

All this data goes to show is that the formation of the “modern” form of hpEurope looks like it had been formed by a just a few unlucky individuals “who were coinfected with two strains, producing a particularly adaptive hybrid type that spread rapidly in Europe,” Gibbons indicates.  This shows scientists that bacterial genomes can adapt to human activity and migration much faster than we thought they could and thanks to the wonders of Iceman’s health problems, we can now trace more deeply the behavior of ancient vs. modern bacterial genomes.

Original Article


A Cup o’ Joe a day keeps the doctor away



Photo by Unsplash

An extensive new study on the health benefits/risks regarding the consumption of coffee over a 30-year period suggests that a few cups of coffee a day has proven to actually be good for you.  Overall, the study looked at three different groups that added up to a total of about 168,000 women and 45,000 men between the ages of about 25-75 (when the study began) who recorded how much coffee they drank and what they ate to the best of their knowledge every four years.  After the 30 years were over, Dr. Frank B. Hu found that those who drank coffee on a moderately regular basis (1-5 cups a day) were less prone to dying of chronic diseases, had a slightly reduced rate of mortality, and that its consumption (moderate) showed little to no signs that coffee causes heart disease or cancer.

Hu found that coffee contains antioxidants, vital minerals like magnesium (which plays a role in a person’s resistance to chronic pain, fatigue, and diseases related to stress and aging), and that it actually improved insulin sensitivity which refers to the body’s ability to maintain blood glucose levels.  When someone has low insulin sensitivity, they are unable to take in proper amounts of insulin and therefore their body compensates by producing more insulin which in turn leads to serious health problems like high blood pressure and heart disease.  Hu also theorized (but did not have enough evidence to claim) that coffee might also act as an antidepressant and had a small effect on suicides and neurological issues.

Overall, the study indicates that because of the health benefits of coffee- it can be incorporated into a healthy diet.  However, this does not mean that non-coffee drinkers should start consuming it as a means of prevention against illness and increasing one’s life span.  In fact, many people could have bad reactions to caffeine and it is known to stunt growth in children and adolescents as well as endanger pregnant women and their fetuses.  Also, overconsumption (over 5 cups a day) can lead to heart disease and other illnesses. All this study goes to show is that moderate consumption of coffee is not dangerous and unhealthy as the world has pegged it for many years.

Original article

A Closer Look- New Groundbreaking DNA Stain



Photo by Nephron

Have you ever imagined what a live cell looks like in person?  Well hopefully someday soon you will because of a certain scientific breakthrough whose name is currently Sir-Hoechst.  As Scientists have tried to observe and analyze cells over the past few decades, a main issue that has caused much chaos in the biology world is that the cells are not just small, they are sensitive and especially to light.

DNA stains are very commonly used in imaging live cells because of their ability to highlight specific functions of the cell.  But these stains require specific lights to activate them.  The problem with this is that the cells, as I said above, are sensitive to these lights, especially intense ones (lights farther ultraviolet end of the spectrum like blues and purples).  When exposed to this light the cells can be damaged or killed.  T add on to these problems, up until recently, DNA stains have not been easily compatible with the high resolution microscopes in which these cells are being viewed by, making the process of imaging much harder.

It seems impossible to see living cells in action, right?  Not anymore!  Scientists have found away to bypass all of these issues with a new DNA stain, SIR-Hoechst.  The new stain was formed by adding a molecule called Silicon rhodamine (SIR) to a already know DNA stain called Hoechst.  The new stain works toward the red end of the spectrum and blocks out any other intense light sources so as not to damage the cell.  SIR Hoechst is also more compatible with the high-resolution microscopes than previous stains.  This new development paves the way for momentous scientific and medical advancements, allowing scientists to watch a cell divide in front of there eyes and pick out an individual cell in muscle tissue. As Johnsson, one of the developers of SIR-Hoechst, describes it, “The introduction of SIR-Hoechst brings bioimaging closer to one of its main goals: observing the wonders of nature without disturbing them.”  My question to you is what exactly will this lead to in the world of science?  Will we be able to watch cell division in class in a few years?  Will scientists correct crucial misconceptions of how cells perform certain processes?  I guess we will just have to wait and see…

Original Article




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