AP Biology class blog for discussing current research in Biology

Author: nekurita

Ethical and Scientific Limitations of CRISPR Gene Editing

The Third International Summit on Human Genome Editing issued a closing statement a few weeks ago calling for a pause on human genome editing – not permanently as some activists had hoped on ethical grounds, but instead for the near future because the technology is not currently sufficiently advanced as to ensure success. Gene editing involves editing embryos outside the womb and then implanting them to establish pregnancy. In addition to the numerous ethical concerns, such as a pathway to eugenics that the technology might lead to, the summit decided that the risks are simply too great at the present time.

CAS 4qyzThis is because the edits made can result in unintended – and sometimes dangerous – consequences for the embryo that traditional DNA screenings may not pick up on. Gene editing works by unraveling the double helix with helicase (just like in DNA replication), cutting the DNA strand with an enzyme, and then having the cell’s own mechanisms, such as primase and DNA polymerase, combined with the new “blueprint” for DNA,  tell the cell the order the nucleotides are placed in and complete the double helix again to form a complete, but modified, DNA strand. However, sections of DNA can be permanently lost or mistranscribed in the process, resulting in genetic disorders or cell malfunction, including cancers. These are similar to the risks that occur during DNA replication and the general life of the cell, but are significantly more likely to occur. Furthermore, mosaicism, often seen on small levels like calico cats (where different cells receive different activated genes than others), can occur on a massive scale, where some cells receive edits and others don’t, leading to health problems down the road for the embryo, if it survives at all.

As a result, the summit, composed of the world’s leading experts in CRISPR technology and research, decided to enact a pause on human genome editing for now. As the technology advances and is made safer, however, they claim that they will reconsider it. Until then, the use of CRISPR is limited to other organisms, such as plants and lab animals.

How “Last-Resort” Antibiotics Kill Bacteria

Polymyxin antibiotics are considered to be “last-resort” antibiotics due to their incredible efficacy, even against otherwise antibiotic-resistant bacteria. However, little was known about exactly how they work – until now. Doxycycline 100mg capsulesResearchers at the University of Basel, Switzerland, have discovered that these antibiotics crystallize the plasma membranes of bacteria.

This crystallization causes the fatty part of a lipopolysaccharide to form a hexagonal structure, which decreases the thickness of the plasma membrane, weakens it, and eventually makes it burst, causing the death of the cell. The lipopolysaccharide normally contributes to the structure and stability of the plasma membrane; if a bacteria is coded without these genes, it will die quickly due to the plasma membrane bursting due to lack of stability. Similarly, the membrane loses much of its structural integrity and collapses when the antibiotic crystallizes it.

This breakthrough is important due to the growing problem of antibiotic resistance: antibiotics are simply less effective than they used to be, as bacteria evolve so that antibiotics no longer kill them. As a result, new antibiotics must be found to maintain efficacy. Now that we know more about why polymyxin antibiotics work, new derivatives can be found to improve public health.

Threat of “Tripledemic” This Year

For the past three years, COVID-19 has been on everyone’s minds. Between the mask-wearing, quarantining, and social distancing performed over this time frame, it is understandable that the spread of other viruses was also curtailed by these measures. However, people are increasingly returning to pre-pandemic activities, and often unmasked – the potential for other viruses to spread rapidly and easily is back.

San Francisco COVID social distancing poster

This winter, influenza is a threat as always – the Centers For Disease Control and Prevention estimate that 2,100-6,200 Americans have already died this year – and fewer Americans have received flu shots this year compared to past pre-pandemic years. but the Respiratory Syncytial Virus (RSV) has the potential to be incredibly deadly this year too.

RSV primarily threatens children and infants, who lack protection with their weaker immune systems. Furthermore, there is currently no vaccine available for RSV. Experts suggest this season to be particularly dangerous because a generation of children have not had frequent exposure to various infections in their lifetime due to the social distancing required by the pandemic, combined with the gradual return of normal activity. When infected, the body’s innate immunity responds. If it fails to stop the virus from spreading, the adaptive immune response begins. Once the infection, in this case RSV, COVID-19, or Influenza are successfully fought off, T-memory cells and B-memory cells continue circulating to prevent serious reinfection. If reinfected, the secondary immune response that occurs will provide better long-term protection.

Children are typically exposed to RSV at least once before the age of two; that number has dropped drastically since the COVID-19 pandemic (not to say that these precautions were not vital and instrumental in controlling the spread of COVID-19). Therefore, they lack this immunity. Unfortunately, there is not much for medical professionals to currently do about this without a vaccine – simply wait for exposure to the virus to rise again. However, the effective vaccines developed for both COVID-19 and Influenza are capable of slowing the spread of both of these viruses – and have been doing so. Through consistent vaccination, we may be able to escape the “tripledemic” experts have been warning of this year.

Is a Vaccine for Cancer Getting Closer?

Vaccines for cancer have long been seen as a possible, but incredibly far-fetched idea. However, the possibility of being vaccinated for cancer, like a polio or flu shot, is getting closer. Scientists and medical doctors are becoming increasingly optimistic about the possibility for a successful vaccine to certain forms of cancer.

Testing vaccine in laboratory. Holding syringe with protective medical gloves closeup. (51714051263)

One type of these vaccines is a dsRNA vaccine, which is designed to replicate the protein that is able to take over a cell by tricking the receptor proteins on the plasma membrane into accepting it. The immune system then learns how to respond to this event and can do so in the future with actual malignant proteins. This works similarly to the COVID-19 mRNA vaccine.

Pancreatic cancer is a promising target – for those in remission, the chance of fatal recurrence is 70-80%, yet relatively easy to detect early with careful testing. The safety study, conducted by the Johns Hopkins Hospital Cancer Center, had no recurrence out of 12 patients. Although very early in the trial process, these are promising initial results that bode well for the future of the trial.

Although not every study is quite as promising. In a more comprehensive, though also not peer-reviewed, study of vaccination against colon cancer, there was no significant difference between the cancer rates of the control group and the experimental group. However, there is promise in the concept, and the field must be explored further before judgment can be cast. At the same time as these other therapies are being developed, inoculation such as the HPV vaccine is preventing cancer by protecting against cancer-causing illnesses. Cancer prevention is a recent, but flourishing field, and one that must be developed further.

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