BioQuakes

AP Biology class blog for discussing current research in Biology

Author: rivisome

Embryo Gene Editing can Ensure Offspring Do Not Inherit a Deafness Gene!

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On January 23, 2020

In Student Post

Denis Rebrikov, A scientist in Russia has done research regarding ways in which he can edit the genome sequence of an embryo in order to prevent the fetus from developing certain gene mutations, specifically in this case a hearing problem or possible complete deafness. His plans are very controversial to some, who believe the possible risks of very harmful mutations to DNA that would be passed onto direct and future offspring, outweigh the possible benefits. However, some people find this scientific possibility to be worth the risk, if it means not passing a potentially very harmful gene down to offspring. If these methods are done correctly, it should alter the genome sequence in the embryo so that future offspring off that embryo will not inherit the negative mutation.

One couple shared their story in detail, in which both parties have a hearing deficiency, the man with partial deafness, and the woman completely deaf. Their biggest hope is to have children who will not inherit hearing issues, because of the apparent challenges they have had to face themselves because of them. They would be the first couple to perform this gene editing on an IVF embryo, so they obviously have some reservations. One of those being publicity, but more importantly the potential risks of using the CRISPR genome editor. They already have a daughter with hearing loss, but they never chose to test her genes for mutations, nor did they get her a cochlear implant to aid her hearing, because of the potential risks of that. When they finally tested her genes, they learned that she had the same common hearing loss mutation called 35delG in both her copies of a gene called GJB2. The parents then tested themselves, realizing they were both 35delG homozygous, meaning their daughter’s mutations were not unique to her, they had been inherited.

If either the mother or father had a normal copy of the GJB2 gene, a fertility clinic could have more easily created embryos by IVF and tested a few cells in each one to select a heterozygote–with normal hearing–to implant. At this stage, Denis Rebrikov informed them that CRISPR genome editing would be their only option. However, the process presents possibly deal breaking risks, such as mosaicism, in which a gene edit might fail to fix the deafness mutation, which could create other possible dangerous mutations like genetic disorders or cancer. The couple has not decided to go through with the editing just yet, but it is something they are open to in the future as more possible new research or test subjects become available.

Explaining the CRISPR Method: “The CRISPR-Cas9 system works similarly in the lab. Researchers create a small piece of RNA with a short “guide” sequence that attaches (binds) to a specific target sequence of DNA in a genome. The RNA also binds to the Cas9 enzyme. The modified RNA is used to recognize the DNA sequence, and the Cas9 enzyme cuts the DNA at the targeted location… Once the DNA is cut, researchers use the cell’s own DNA repair machinery to add or delete pieces of genetic material, or to make changes to the DNA by replacing an existing segment with a customized DNA sequence.” -US National Library of Medicine Genetics Home Reference

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Woman with a hearing aid 

If you had the opportunity to alter something in the gene’s of your baby’s embryo, would you? Under what circumstances would you consider this, and what risks might stop you from deciding to do it? Comment down below.

 

 

Your Gut Microbiota Could be Influencing Mental Health Disorders: Could Psychiatric Medications Change This?

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On November 17, 2019

In Student Post

Mental Health and Gut Bacteria 

Newly published research in rodents and continuing research in humans explores the effects of psychiatric drugs, including antidepressants, on the composition of gut bacteria. They have examined how the effects on gut microbiota, typically caused by naturally occurring metabolic changes in the gut, may influence connection with the nervous system rendering some negative effects on mental health. The most common mental health conditions connected to changing composition of the gut microbiome are anxiety and depression. 

This comes from a recent study that Medical News Today has released, reporting on different bacteria that play a part in synthesizing neuroactive compounds in the gut. These neuroactive substances interact with the nervous system, influencing the likelihood of developing depression or anxiety. This research has been proved more extensively and directly in rodents, but the research in humans provides similar conclusions, allowing scientists to partially conclude the effects in humans–research on this topic in humans is likely to expand greatly in the near future. 

How can gut microbiota be affected by different psychotropics? 

The Study and Results:  

Provided this link between changing gut bacteria and mental health, researchers from University College Cork, in Ireland, set out to investigate this in rodents. First, the team “investigated the antimicrobial activity of psychotropics against two bacterial strain residents in the human gut, Lactobacillus rhamnosus and Escherichia coli.“The psychotropics that the researchers conducted this study with included fluoxetine, escitalopram, venlafaxine, lithium, valproate, and aripiprazole.

Then, the scientists studied “the impact of chronic treatment with these drugs” on the rats’ microbiota. The scientists gave the rodents psychiatric drugs for a period of 4 weeks, ending the study by inspecting the effects of the drugs on the rodents gut bacteria. They found that lithium and valproate, mood stabilizers that can treat conditions including bipolar disorder, raised the numbers of certain types of bacteria. These included Clostridium, Peptoclostridium. On the other hand, selective serotonin reuptake inhibitors (SSRIs), fluoxetine and escitalopram (both antidepressants), ceased the growth of bacterial strains such as Escherichia coli.

“We found that certain drugs, including the mood stabilizer lithium and the antidepressant fluoxetine, influenced the composition and richness of the gut microbiota,” says head researcher Sofia Cussotto. 

Conclusions from the Study, and what the Future Holds 

Dr. Serguei Fetissov, a professor of physiology at Rouen University, in France commented on the study, saying: “At the moment, it would be premature to ascribe a direct role of gut bacteria in the action of antidepressant drugs until this work can be reproduced in humans, which is what the authors now hope to do.”

However, the implications and further goals and hopes of this research is to directly prove that “psychotropic drugs might work on intestinal microbes as part of their mechanisms of action,” says Cussotto

Do you think it is too early to assume a direct connection between gut bacteria and mental health in humans? Comment about this below.

Further Research

https://www.medicalnewstoday.com/articles/amp/326299 

https://www.medicalnewstoday.com/articles/319117.php#1 

 

 

 

A Gene Mutation that Keeps You Awake and Functioning for Longer

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On October 27, 2019

In Student Post

INTRODUCTION:

Could a gene mutation really allow someone to finish college in two and a half years? The answer is yes! We all wish we could get by a function perfectly, or even better than normal, on less sleep. This is a reality for some, specifically people with a rare gene mutation. I saw an article titled, “Why Do Some People Need Less Sleep? It’s in their DNA,” and I thought this was a rather interesting topic, because I have never heard of less sleep ever being a positive thing. I am interested to see more research on this, and the possibility of it being an added benefit for others. It prompted me to think about whether or not this is something I would want, considering some of the implications. 

People with this gene mutation can get significantly less sleep than recommended for function, as little as three to four hours—without suffering any health consequences and while actually performing on memory tests as well as, or better than, most people. There is now a new study correlating to a new genetic mutation found with these “powers,” after previous studies revealed other types of mutations that may impact sleep.

 

HOW DID IT START?: 

To understand this rare ability when presented to them, scientist Ying-Hui Fu and her team, at the University of California, San Francisco, in 2009, began this study on some individuals, but also on mice, to simulate a similar sleep equilibrium to humans. After a woman came in claiming she was functioning at a high level on very short sleep time, scientists needed to understand, as lack sleep is typically correlates with health issues such as risk of heart attack, cancer, or even Alzheimer’s. They initially found a small mutation in the DEC2 gene, a transcriptional repressor (hDEC2-P385R) that is associated with a human short sleep phenotype. According to UCSF, DEC2 helps regulate “circadian rhythms, the natural biological clock that dictates when hormones are released and influences behaviors such as eating and sleeping. This gene oscillates this particular c schedule: rising during the day, but falling at night.” The newer study reveals that the DEC2 gene lowers your level of alertness in the evening by binding to and blocking MyoD1, a gene that turns on orexin production, a hormone involved in maintaining wakefulness. Fu says the mutation seen in human short sleepers weakens DEC2’s ability to put the breaks on MyoD1, leading to more orexin production and causing the short sleepers to stay awake longer.

THE NEW GENE MUTATION: 

In a new study, released on October 16, 2019, by Science Translational Medicine brought on by a mother and daughter duo, mice were studied again to mimic the human sleep pattern. The mice again required less sleep, and were able to remember better. In the study, researchers identified a point mutation in the neuropeptide S receptor 1 (NPSR1) gene responsible for the short sleep phenotype. The mutation increased receptor sensitivity to the exterior ligand, and mice with the mutation displayed increased mobility time and reduced sleep duration. Even more interestingly, the animals were resistant to cognitive impairment induced by sleep deprivation. The results and findings in the study point to NPSR1 playing a major role in sleep-related memory consolidation. NSPR1 is a gene that codes for a brain receptor that controls functions in sleep behaviour and awakeness. In the new study, when mice were given this gene mutation, there were no obvious health, wellness, or memory issues over time. Although the family members did not appear to experience any of the negative effects of sleep deprivation, the researchers make sure to emphasize that longer term studies would be needed to confirm these findings.

WHAT DOES THE FUTURE HOLD?: 

In the future, a possible drug could be produced to synthesize a change in one of these genes, as a possible treatment for insomnia or other sleep disorders. We would need a lot more research about their functions, though, because of possible negative neurological side effects. 

If a medication with these powers were to exist, do you think it would cause social issues regarding some  possibly forcing certain individuals to take it to work longer hours/get more done? Do you think that it should be available to everyone, or only people with certain conditions? Comment about this below. 

 

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