AP Biology class blog for discussing current research in Biology

Tag: red blood cells

Editing Sickle Cell Disease…

CRISPR gene-editing has recently been involved in the studies of sickle-cell anemia, a gene mutation that causes a decline in children’s health. Sickle cell anemia makes it difficult for oxygen to transport sufficiently throughout the body due to unhealthy blood cells. Some symptoms of the condition are shortness of breath, pale skin, colder body temperatures, headaches, etc…

Photo by SciTechTrend

Looking at sickle-cell anemia from a molecular standpoint, the mutation alters the red-blood cell by producing the wrong form of molecule which is referred to as a subunit. Out of the four subunits in hemoglobin, an “adult-expressed” subunit also known as beta” is produced. In contrast, fetal subunits create “gamma” subunits which are the appropriate molecules in red blood cell development for children. The unfortunate results of a mutated gene are crescent-like and inflexible red blood cells, which can form blockages against the flow of blood and oxygen through blood vessels.

In the past, scientists have been able to increase the gamma production in hemoglobins by “reversing” beta subunits to gamma subunits through a form of therapy, yet in a recent study scientist dove deeper to prevent the mutation as a whole. With gene editing technology, CRISPR has been reported to be useful in putting an end to the hereditary mutation. In that, scientists can identify the mutation and cut the DNA target out by using CRISPR. A specific piece of the DNA, also known as the “control section”, is introduced to gamma subunits during a  process of molecular conversion therapy and the ends of the control section are placed together after the mutated code for the gene is removed. Ultimately, this is said to reduce the adult-expressed subunits and stimulate higher levels of gamma subunits in fetal hemoglobins so that young children affected by sickle cell can avoid invasive treatments in their future.


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 

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