BioQuakes

AP Biology class blog for discussing current research in Biology

Author: zerillium

How CRISPR/Cas9 could one day prevent AIDS

CRISPR/Cas9 is a new gene editing tool that can target and modify DNA with great accuracy.  This new tool has many scientific uses, including treatment of many diseases.  Recently, several breakthroughs have been made in treating HIV with CRISPR Cas9.  However, a number of issues with the tool have come up at the same time.

To understand how CRISPR eliminates HIV, one must know how HIV replicates. HIV replicates by taking over a host cell and injecting its RNA into the cell.  This RNA becomes DNA and joins together with parts of the host cell’s DNA.  After entering the cells, the virus can lay dormant for several years, but will eventually start replicating and taking over other cells.  The standard form of treatment for HIV is an antiretroviral.  While antiretrovirals can be very effective at limiting the spread of the disease, it cannot fully remove it or stop it forever.

HIV virus

image source: http://bit.ly/1S4bcWY

The CRISPR Cas9 could potentially be used to inhibit the spread of HIV by editing the virus out of a cell’s DNA.  Researchers at The University of Massachusetts Medical School have been developing a technology to perform this impressive task.  While there have been several successful trials in preventing HIV from spreading, several trials have lead to increased resistance for the HIV.

“When we sequence the viral RNA of escaped HIV, the surprise is that the majority of the mutations that the virus has are nicely aligned at the site where Cas9 cleaves the DNA, which immediately indicates that these mutations, instead of resulting from the errors of viral reverse transcriptase, are rather introduced by the cellular non-homologous end joining machinery when repairing the broken DNA,” says Chen Liang, a senior investigator at the Lady Davis Institute at the Jewish General Hospital and the Associate Professor of Medicine at the McGill University AIDS Centre.

These mutations alter the strand of DNA, preventing the CRISPR Cas9 from recognizing it.  If the CRISPR Cas9 cannot recognize the virus, it cant remove the viral DNA, allowing the virus to create more copies of itself.  Despite these limitations, researchers like Liang are confident that they can succeed.

article: http://esciencenews.com/articles/2016/04/08/hiv.can.develop.resistance.crisprcas9

New Research Uncovers Bat Super Immunity

Recent research has discovered a unique ability in bats to carry diseases but remain symptom free.  This ‘super immunity’, as it has been called by researchers, is currently a mystery to scientists but could one day provide methods for achieving super immunity in humans.

Bats are know to carry many diseases that are deadly to humans like the Ebola virus, Hendra virus, and MERS (Middle Eastern Respiratory Syndrome).  For some reason, their immune system allows them to not get sick or show any signs of the disease.  Research published in the journal Proceedings of the National Academy of Sciences might allow us to better understand why this strange phenomenon occurs in bats.  These researchers looked deep into the immune system of bats, especially into the interferons.  An interferon is defined as “a protein released by animal cells, usually in response to the entry of a virus, that has the property of inhibiting virus replication.”  According to the research, bats only have three interferons, which is less than a quarter of the number of interferons possessed by humans.  “This is surprising given bats have this unique ability to control viral infections that are lethal in people and yet they can do this with a lower number of interferons” says Dr. Michelle Baker, an immunologist at CSIRO’s Australian Animal Health Laboratory. Researchers also found another notable difference in how bat immune systems work as a whole.  While most mammals only activate their immune systems when they are infected by something, bats seem to always have active immune systems. Having the immune system active at all times can be dangerous in most animals because it can be toxic to cells, but bats seem to be perfectly fine.

Myotis yumanensis (Yuma myotis)

Image Source: http://bit.ly/1T4Qn0r

While information on bat super immunity may be limited at the moment, future research could prevent outbreaks like the Ebola virus in West Africa.  Dr. Baker describes the potential of this research well by saying, “If we can redirect other species’ immune responses to behave in a similar manner to that of bats, then the high death rate associated with diseases, such as Ebola, could be a thing of the past.”

Article Source: http://www.biologynews.net/archives/2016/02/22/bat_super_immunity_could_help_protect_people.html

Further reading: http://mashable.com/2016/02/24/bat-super-immunity/#_6DA21uIkiqU

 

New Discoveries Link Stomach Bacteria with Autism

Autism rates are on the rise in the US, and the cause of this condition is still unknown.  Autism is mental condition, present from early childhood, characterized by difficulty in communicating and forming relationships with other people and in using language and abstract concepts.  According to the CDC, 1 in 68 children will be born with autism.  This is a huge increase from the 1 in 150 children in 2000.  It is unknown how autism starts, but something causes a change in brain structure or function that leads to the condition.  New research shows that it could possibly be related to the human gut microbiome.

Mycobacterium tuberculosis Bacteria, the Cause of TB

Image Source

Since the 1990’s, the gut microbiome has been the topic of copious amounts of research.  Scientific developments since then have uncovered the influence that the gut microbiome has on human health.  Disorders in the microbiome have been linked to conditions like asthma, rheumatoid arthritis and even some cancers.  New research claims that over representation of Clostridium or Desulfovibrio bacteria in the microbiome could possibly cause the autism spectrum disorders.  According to the report, “Studies of fecal DNA extracts have found Clostridium or Desulfovibrio clusters over-represented in children with gastrointestinal complaints and ASD(autism spectrum disorders) as compared to children with similar GI complaints but typical neuro-behavioral development”.  A another possible link between the microbiome and autism was found when clinical improvement was reported in children with autism who developed fever, received antibiotics, or ingested probiotics— treatments that likely altered gut bacteria, thus limiting the effects of the bacteria. 

While the connections may be weak right now, discovering potential connections between autism and the gut microbiome allows for more research and a potential cure one day.  One researcher plans on conducting a clinical study using fecal transplants from healthy donors. The goal of this study is to see if the treatment “would reduce autism symptoms by normalizing an individual’s community of gut bacteria.”

Original Article

Further Reading:

https://www.autismspeaks.org/science/science-news/autism-study-more-evidence-linking-altered-gut-bacteria-asd

 

New Research Sheds New Light on Cancer Preventing Proteins

Cells in the human body are constantly dividing. Whenever cells divide into two, the DNA within them must be copied as well. Most of the time this process works as planned, but some times the DNA can be copied incorrectly. Other factors such as UV rays and radiation can damage DNA and lead to problems like cancer. While these errors in DNA copying can cause significant mutations, they are usually corrected by certain proteins within the cell. New research at the University of Michigan is allowing scientists to get a better idea of how these proteins go about finding the damaged sites and repairing them.

Mutación ADN

Image Source

In this study, researchers at UM examined the MutS protein in bacteria. According to Lyle Simmons, associate professor of molecular, cellular, and developmental biology at UM, it has been known for a long time that the MutS protein could find and repair errors in DNA. “MutS is the first protein involved in DNA mismatch repair and is responsible for detecting rare errors that can predispose people to certain types of cancer, a hereditary condition called Lynch syndrome or cancer family syndrome. If a person’s mismatch repair system is hindered, the mutation rate increases 100-to-1,000 fold” says Simmons.  Despite knowing what these proteins do, it remained unclear as to how they perform these tasks.

To see how the protein works, researchers “fused the MutS protein to a fluorescent tag and activated fluorescence with a laser.” They then studied the protein’s actions inside of a bacterial cell. Tagging the proteins with fluorescence allowed researchers to track its movement through the cell. Scientists observed that MutS moved quickly through the nucleoid but slowed down at DNA replication sites. This indicates that the proteins look for sites of replication rather than individual mismatches. The protein then searched the new DNA being created for errors. Mismatches occur when the wrong nitrogenous bases are paired with each other. “The mismatched pair kinks the DNA at the replication fork where DNA is made. MutS positions itself at that fork so it’s ready to catch any mistakes. As an added bonus, this positioning likely tells MutS which side is correct and which side is the new, altered DNA.” says Julie Biteen, assistant professor of chemistry.

Despite the study being performed on bacteria, it is very likely that the same process occurs in human cells.  This discovery is very important because it provides information that will be essential to learning more about how the body responds to mutations.  Further advances in this area of study could possibly help researchers understand cancer better.

Original Article

How Intestinal Microbiota Could Prevent Asthma

There are trillions of microbiota living in the average human intestine.  These microorganisms have formed a mutualistic relationship with humans and take on a number of functions including digestion, vitamin production, and the prevention of harmful bacteria growth.  In addition to these essential roles, new research shows that four types of these organisms may prevent asthma

Bacteria

 

The four types of bacteria are Faecalibacterium, Lachnospira, Veillonella, and Rothia.  Currently, some scientists think that these bacteria, FLVR for short, help prevent asthma by creating chemical byproducts.  These byproducts are thought to help train the immune system to attack harmful germs and to prevent inflamation.  Having these microorganisms is essential for the development of children. It is possible that the absence of the bacteria can lead to many health problems for people, including asthma.  Stuart Turvey, a pediatric immunologist at the University of British Columbia and a co-author of the study, thinks that being exposed to the FLVR microorganisms at very young ages is essential for preventing asthma and has said “Having the right bacteria in place at the right time is really important, especially in those early months of life.”  Despite their research, scientists do not know much about why the immune system possibly malfunctions when it is not exposed to the bacteria.  However they do know that the immune system becomes “confused” and creates inflammation in the lungs.

These new findings on asthma could possibly explain why asthma’s prevalence has tripled to quadrupled in first world countries in the past 30 years.  The advanced medical knowledge and technology in these countries could possibly be creating an over sterilized world.  Due to more and more doctors treating common sicknesses with antibiotics, human intestines are starting to become too clean and they lack the essential microorganisms including FLVR.  The absence of of these FLVR bacteria is likely to put more people at risk of developing asthma.  One study showed that many Canadian school children had very low levels of FLVR bacteria, putting them at high risk of developing asthma. Another study performed on mice strengthens the viewpoint that these bacteria prevent asthma.  The study examined new born mice by exposing some to FLVR and leaving the rest without the bacteria.  The results showed that the mice exposed to the FLVR at very young ages had much lower rates of inflammation in the airways.

Original Article

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