AP Biology class blog for discussing current research in Biology

Author: mytosis

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.


Inhale RNA, Exhale Your Worries

The focus of a recent study is inhalation genetic therapy to give patients with Cystic Fibrosis relief when they breathe. A defective gene in people with Cystic Fibrosis causes a mucus build-up in specific organs. The respiratory complications due to mucus build-up in the lungs are which infections, clogged airways, inflammation, and respiratory failure.

Recently, scientists developed a study that involves mice inhaling messenger RNA. The messenger ribonucleic acid is genetically manipulated so that it contains an oxidative enzyme called “luciferase”, which is known for causing bioluminescence. Scientists manipulated the mRNA by “packaging” or combining the enzyme with a polymer that would be inhaled into the lungs of the mice. The inhaled polymer would then travel through the respiratory system and be taken in by the lungs, where it would eventually be broken down by cells within the lungs. Scientists were able to distinguish if the experiment was successful as the light from the luciferase combined with the mRNA could be detected from within a lung cell.

Another experiment was conducted with similar circumstances in that it tested genetically modified mice cells that glowed red from the cell’s reception of mRNA. This offered the scientists the opportunity to test a range of mRNA-polymer dosages to quantify or count the resulting “red” mice cells.

As we continue this road down modern medicine, mRNA can be evolutionary for patients with Cystic Fibrosis because the messenger RNA can recreate functional copies of itself to produce CFTR protein (cystic fibrosis transmembrane conductance regulator protein), which is the protein that codes and determines the functionality of the CFTR gene. Could mRNA polymers possibly be a treatment for milder respiratory issues like asthma? This experiment might just be a breakthrough in the world of medicine, as strands of ribonucleic acid could be the answer to ending compromising respiratory complications.

An Exception to Microbiome Functionality

A recent study was developed to understand how HIV corresponds to the microbial communities of the female sex organ. Dr. David Fredericks- a physician and college professor that teaches “Allergy and Infectious Disease” at University of Washington, led a study on the relationship between the diversity of bacteria in the vagina and how it may lead to HIV. The research population specifically focused in on sub-Saharan African women, who make up 56% of the continent’s infected population.

HIV-infected T cell

Scientists have come to discover that the greater the diversity of a microbiome, the more equipped that region of the body is for combating infections. Although- this concept is strictly relative to the mouth, intestines, and nasal passageway because a variety of bacteria inhabiting a vaginal microbiome can be very detrimental to a woman’s health. One of the leading risks from having a diverse vaginal microbiome community is the “human immunodeficiency virus”.  This virus can be transmitted through sexual contact, childbirth, nursing, or the usage of unsanitary needles. One’s immune system is weakened after contracting HIV because CD4 cells are damaged, which makes it harder for the body to fight off illness. Dr. Fredericks has revealed that the presence of a microbe called Parvimonas Type 1 is usually not a dangerous bacteria, yet the microbe is linked to the virus when there is a higher concentration of it in the vaginal microbiome.

Dr. Fredericks accomplished making this new find by using a strategy called the “dose-dependent effect” to measure the amount of “bugs” in a microbiome community in correlation to the risk of contracting HIV. In doing so, the scientists took cultures from 87 women who were infected with HIV and 262 cultures from women who tested negative for HIV to compare the bacterias found in both microbiomes. During the second half of the study, biologists used screening through a method called “PCR“and identified 20 types of bacteria that could potentially be linked to the virus. The bacterias involved in generating the virus in the female reproductive system were narrowed down to seven specific strains of rogue bacteria. Since the discovery, the biggest question revolving around HIV is determining how to permanently reduce the concentration of these illness-inducing bacterias.

A Much-So-Symmetrical Embryo

Developmental biology has taken a step further in understanding the connection made between the placenta and fetus by testing a hypothesis that involved slowing down the growth of one limb on an animal. Scientist Alberto Roselló-Díez used laboratory raised mice to test out his hypothesis by genetically manipulating the cells of a fetus in a petri dish. He then inserted the genetically modified cells into the mouse’s back left leg. A deeper look at Díez’s work explains that he uses a “p21” suppressor which is also known as an “antiproliferative”. In doing so, Roselló-Díez is suppressing chondrocyte cells (found in cartilage) from forming, thus preventing the mouses bones from lengthening.

In response to the cellular suppression, the nature of the fetus’s growth as a whole slows down to the growth rate of the left hind leg;  putting me in the mind of the phrase- “no man left behind”. This is described to be a “compensatory mechanism”, in which the entire fetus makes up for the compromised development of the mouse to keep it’s symmetry.

You might be wondering- “how does the placenta play into this?” Apparently, the cells of the placenta systemically communicate to the tissues of the other limbs, and warn them to “SLOW DOWN!” Therefore the fetus of the mouse relies on biological signals from the mother’s placenta.

Picture by Maneesha S. Inamdar

All in all, minimizing the growth rate of limbs is intriguing because it leaves me wondering the extent of the experimental purpose. Will it be that in the future we will use the p21 suppressor on human fetuses? Will this study lead to a breakthrough for unanswered cosmetic and orthopedic phonomena? These questions are yet to be undertaken by developmental biologists and maybe even doctors.

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