AP Biology class blog for discussing current research in Biology

Author: hypotheoni

Gene Editing Used to Eliminate Invasive Rodent Species’ on Islands

Species of Invasive House Mice have been not just a nuisance, but potentially dangerous and damaging on islands for hundreds of years. These house mice can be dangerous, as they have the potential to spread diseases by getting into food stores or biting humans, to cause asthma or allergy flare ups, and to bring unwanted insects such as fleas, ticks, or  lice into a home. Scientists have been looking for a way to remove these invasive pests from homes throughout time, and to no avail. Now, they have found a new way to eliminate entire populations of these pests at a time in a mere 25 years. 

Mouse white background

With the emergence of DNA editing technology, scientists have found  a way to edit the mice’ DNA so that a certain chunk of the edited DNA is inherited way more often than the average trait. This lab-created trait is called a gene drive, which had in the past been used to successfully reduce many pesky populations of insects before, but had not been proven effective in mammals. To fix this issue, scientists decided that they most discover more about the haplotypes, which are “naturally occurring group(s) of genes that gets passed on as a unit during replication” within house mice. They discovered that the t-haplotype within house mice get passed on to offspring 95% of the time, instead of the usual percentage of 50%. The editing of this t-haplotype was found to be very favorable. This haplotype evolved naturally within these house mice, meaning that will continue to be present in the wild, and there is no projection of resistance to this haploytpe being found anytime soon. Another reason why the editing of this gene sequence is favorable is that it is only present in the invasive species of house mice, meaning that it will not effect other noninvasive species


Now the only question is, how will scientists change this haplotype? Well, as CRISPR technology is emerging and evolving, it has been found as the obvious tool to use to edit this gene. Molecular Biologists have used CRISPR to edit the mice’ DNA to add the CRISPR tool into the t-haplotype. There are two affects of this change, when male mice with a heterozygous genotype of the edited gene mate, the CRISPR genes inserted will cause any baby female mice created to be infertile. The other effect of this genetic change is that males with the homozygous genotype of the edited gene will be sterile.


Now you might be asking, “has this format gene editing to eliminate the population of the invasive house mice actually been proven effective in any way?” Well, the answer to that is complicated, as scientists have not yet properly tried it out on any island populations. They have used computer simulations to test their hypothesis, finding that in the simulation that after adding 256 mice with the altered gene into the population, the island population of this mouse would go extinct within 25 years. Scientists have still only tested the changing of the t-haplotype within these mice in labs, and have not yet tested the use of CRISPR to effectively damage genes needed for fertility in the house mice. More testing must be done to effectively ensure that this method of eliminating the species is effective, and so we might have to wait some years to begin the overall mission. Overall, scientists are hoping to find a way to eliminate populations of invasive species such as the house mouse in timelines smaller than 25 years,  and many are looking to the future of CRISPR technology as the true way to achieve this goal.

The Science of Love

The neurobiology of love is not as simple to figure out as one may think. Throughout time, researchers have studied the prairie vole when looking to discover more about what exactly is going on in our brains when we fall in love. The prairie vole is used because they form monogamous relationships, in which they show empathy for and display actions that we would describe as love. The monogamy of prairie voles was tested and proven nearly 50 years ago, and since then, we have been researching prairie voles to discover the neurobiology of their love.

Prairie vole.gif
When first looking at exactly what happens in a prairie vole’s head when they “fall in love” the hormones oxytocin and vasopressin were found to play a key role in the bonding of prairie voles. These hormones work just as any hormone we have learned about in this AP Biology class does, they are peptides that bind to receptors, resulting in the change of the shape of the receptor, resulting in a change within the cell. This signal caused by oxytocin and vasopressin has been shown have the ability to change a solitary or polygamous prairie vole, into one that forms a monogamous bond with another prairie vole. This is unique to other voles, as the receptors for these hormones in prairie voles are in a separate location to those within other types of voles. This discovery opened up a doorway into understanding how the location and abundance of hormones receptors can affect the bonding of animals or even ourselves. In order to truly understand this though, researchers had to find a way to manipulate the ways that genes encode these receptors.

Vasopressin labeled  Oxytocin

Vasopressin                                               Oxytocin

Although this phenomenon has been well studied in the past,  the invention of CRISPR technology has opened many more doors into studying the ways that these hormone receptors work. Throughout time, it has been accepted that oxytocin in the true hormone that controls the bonds of these prairie voles. But, after a research team used CRISPR to “delete the gene that encodes the oxytocin receptor in prairie vole embryos,” it was found that the genetically modified prairie voles were still able to form bonds as easily as their non-modified brethren. Scientists are now trying to really figure out what the biology of the love of these voles is, as their original hypothesis that oxytocin controls it has been found incorrect. Scientists are now looking to hormones such as vasopressin, to see if that was the missing part of the puzzle they need. This discovery that oxytocin is not the entire basis of the bonding of prairie voles does show that as usual, love is less complex than we may think, and that they must look at the neurobiology of love as having a much bigger scale than before thought of.


Currently, scientists are aiming to look at the activity of genes in the brain to further look to what causes love bonds. Recent studies like this have shown that after the voles have mated, genes important to memory and learning are turned on, and that their brain’s reward structure turns on after a stable amount of time with a bond. These studies have also proven that the voles brains become “activated,” once they have created a bond, as their neural activity “lights up” and their brains “re-wire themselves.”

“How does this relate to us humans?” you may ask. Well, the ways that prairie voles react to their bonds can show us what an evolved brain, which neurologically is wired to have a partner. The studies done on prairie voles inspired scientists to look back closer at the reward structures pf the brain looked at in studies for prairie voles, and it was found that humans had similar responses to the voles. Overall, with much more time to let research and technology develop, studies on prairie voles have definitely taken us one step closer in understanding the science of love.

New mutation of COVID-19 discovered

A new version of COVID-19 that is resistant to remdesivir was discovered in organ transplant recipients. “What is remdesivir?” you may ask. Well, remdesivir is one of the very few medications approved to treat SARS-CoV-2. This medication is extremely important for the treatment of COVID-19 within transplant patients because the other medication, Paxlovid, has been found to interfere with immunosuppressants. Remdesivir works by stopping the spreading of SARS-CoV-2 by stopping the virus from copying itself. The virus replicates itself using the enzyme polymerase, which replicates strands of DNA using 2 strands.


It was reported that two COVID-19 vaccinated liver transplant patients of NYU Langone were infected with SARS-CoV-2, and then that the remdesivir had no effect on them. To investigate, the patients were swabbed before their release from the hospital. Although they had already been vaccinated from the disease before their surgeries, the two patients began showing symptoms of SARS-CoV-2, such as lingering fatigue, cough, and fever. Both patients were readmitted to the hospital when their symptoms got worse. 

SARS-CoV-2 without background

Researchers found that the patients were both infected with the non-mutated form of SARS-CoV-2 (the one non-resistant to remdesivir), and the mutation happened sometime after the infection. It was discovered that the virus developed a different form of their polymerase, and that that form of polymerase was more resistant to the remdisivir. The researchers stated that this mutation could have been created because of “the antiviral treatment itself, combined with the patients’ weakened immune systems”. This weakened immune system could make cells such as natural killer cells have a harder time fighting off against the virus, because of the immune systems’ inability to fight off everything coming at it. 


The discovery of this mutation is important to the study of COVID-19, as we are now more aware of the fact that we have to continue to monitor the disease. This study also opens a door of investigations towards the mutations the virus might make in resistance to the vaccines. Now that we know the things that the virus can mutate against, we have a precedent to how it might mutate in the future.


Do mosquitos bug some people more than others?

Over time, many have questioned whether or not some people are more susceptible, or attractive, to mosquitoes than others. Some have thought that it was one’s blood type, some have thought it was due to smell, and some have thought that the idea is truly a myth. It was highly suggested that attraction to mosquitos was due to scent, but never confirmed if true and what scents they would be attracted to.

Aedes aegypti during blood meal

A recent study has that scent is the answer to attraction of mosquitoes, and what scents they prefer the most. In this study, participants were asked to wear stockings on their arms for 6 hours, to imbue the stocking with each person’s unique smell. The researchers then put one piece of a volunteer’s stocking next to a piece of another observer’s stocking, and monitored whether or not the mosquitoes seemed to prefer one stocking over the other. The researchers concluded the mosquitoes definitely appeared to prefer certain stockings over others, one of the stockings in particular had “an attractiveness score ‘over 100 times greater’ than that of the least attractive subjects”. 



After the study, the researchers found that mosquitoes preferred stockings with more carboxylic acids. Carboxylic acids are organic compounds, which are produced by humans on our skin, moisturizing us, protecting us, and producing a sweaty smell on our skin. From the time we are born, us humans keep a constant Carboxylic-acidlevel of carboxylic acids on our skins, meaning that for the most part, our “attractiveness” towards mosquitoes is level for our entire lives. 




You might think that this is the end, that this study has proven that there is no hope for you to lose the status of “mosquito magnet” if you already are susceptible to mosquito bites, but this is not true. This study leads the way in future projects to reduce mosquito bites in mankind, as it revealed what the true issue we had to attack was. A biologist who specializes in mosquito research, Omar Akbari, has stated he is using the research to aid him in the development of mosquito repellents that will work for long periods of time(months). Akbari has already discovered specific carboxylic acids that mosquitoes are particularly attracted to, and is working with the Department of Defense to aid them in their work in insect control. He is working alongside the US government to develop these repellents, truly proving that there is hope for those who feel they are 


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