AP Biology class blog for discussing current research in Biology

Tag: fruit flies

Missing Ribosomal DNA in Fruit Flies

This research was conducted by Yukiko Yamashita and her team on fruit fly germline stem cells and highlights the cells’ ability to retain their ribosomal DNA and continue to reproduce endlessly, giving immortality to these cells. 

Ribosomal DNA contains genes for ribosomes, which create the cell’s protein. In this case, it has a flaw because some of these genes will form a loop and pop out of the genome during cell division. If too much rDNA is lost in each generation, it would hinder their ability to build proteins, leading to extinction. However, the research showed that this is not happening, and germline stem cells are able to maintain their rDNA.

The research team used microscopy techniques to visualize rDNA in fruit fly testes and observed that their stem cells have a built-in mechanism to retain these essential genes. This mechanism involves a skewed swap of genomic sequences between two identical chromosomes, leading to one chromosome having extra rDNA, which is then passed to daughter stem cells. Fruit Flies that lack ribosomal DNA have different appearances such as unusual abdomen patterns.

The implications of this research go beyond fruit flies. Understanding how rDNA repeats are maintained in various species, including humans, is crucial, and the process is expected to be conserved across different organisms, even if the specific molecules involved are not. This research provides valuable insights into the mechanisms of immortality in germline stem cells and has the potential to inform our understanding of similar processes in other species. 

Drosophila melanogaster Female

In AP Bio we learned about the production of proteins and their transport system. The endomembrane system consists of the nucleus, the nuclear membrane, ribosomes, the rough ER, vesicles, the Golgi body, and the cell membrane. The proteins are made by ribosomes, some of which rest on the rough ER and others that float in the cytoplasm. Then they are transported by vesicles to the Golgi body, where they are packaged with a lipid label, and transported to the cell membrane, through which they exit the cell. In the case of fruit fly testes, essential genes are preserved becasue along the protein’s formation and transportation, some of its proteins exit the genome allowing the cell to preserve them. 

I chose this topic because the endomembrane system was my favorite thing to learn about, and I find genetic mutations interesting.

Where does the lost RNA go and what are the implications of it being in the cytoplasm?


Can Fruit Flies Really Help Cancer Research?

Fruit fly (7424411436)In a study conducted at the University of California, Berkeley, researchers identified similarities between fruit flies and humans with cancer and believe this research could lead to prolonging the lives of cancer patients. Cancer, a disease where cells “grow uncontrollably and spread”, was diagnosed in 18.1 million new cases and claimed the lives of 9.5 million new patients worldwide as recently as 2018. The Berkeley researchers took a new approach to tackle cancer by “launching an attack against the destructive chemicals cancer is throwing off.” They believe this new method could increase patients’ survival rate and overall health.

David Bilder, a UC Berkeley professor, stated that the goal of the research was “to help the host deal with the effects of the tumor, rather than killing the tumor itself”; this represents a different approach to cancer treatment since most current treatments focus on killing the tumor and the unhealthy cells. Conventional treatments create serious side effects in patients as the treatments impact healthy cells too. Bilder’s research attempts to interfere with the blood-brain barrier, a feature of the central nervous system which is key in regulating microorganism entry and exit from the bloodstream and interstitial brain fluid. It is believed that inflammation caused by tumors leaves the blood-brain barrier open, but interfering with that process might slow tumor growth allowing for improved patient quality of life and life expectancy. This process could eliminate the need for toxic drugs that harm healthy cells while targeting cancer cells.

During the research a few years ago, Bilder’s team also learned some interesting new information about the impact of insulin on cancer. They concluded that tumors in fruit flies release a substance that blocks the effects of insulin. Insulin, a type of protein that coordinates organism activities while maintaining normal blood glucose levels, is a crucial component of our body system. It allows cells to absorb glucose which can serve as energy or convert to fat if necessary. Without insulin, cells are unable to use glucose as fuel and bodies would start breaking down their fat and muscle resulting in weight loss. This can pose an issue because it could lead to cachexia (an effect of cancer where patients are unable to maintain weight) which sadly kills ⅕ of cancer patients. Although more research is needed to investigate the relationship between insulin and cancer in humans, sugar may play a role in the growth of cancer.


CSIRO ScienceImage 355 Representation of Insulin Structure

Insulin Structure

I believe that this new approach to cancer treatment is a fascinating angle to effectively treat cancer patients. As someone who has experienced cancer in two close family members, I know firsthand how draining the treatments are because they target healthy cells as well as cancerous ones; this treatment simply diminishes these side effects. As Bilder states, “We think this is a real blind spot that hasn’t allowed scientists to address questions about how the tumor is actually killing outside of its local growth.” It could offer a “complementary way of thinking about therapy.” It is great to see new ways of thinking address a disease that impacts so many people.

Sleeping: Switch off the Lights, Switch on the Neurons


Photo taken by André Karwath

Photo taken by André Karwath

Scientists at Oxford University’s Centre for Neural Circuits and Behaviour “identified the switch in the brain that sends us off to sleep”  (see original article) by doing a study on fruit flies (Drosophilia).  This part of the brain had been discovered in 2011 (see this article about the discovery), but the new research identifies more specifically the molecules and sleep-causing cells involved. 

The switch (which is made of several molecules) in the fly brain is likely similar to the switch in the human brain because both species have a similar group of sleep neurons.  This switch regulates the neurons that cause organisms to sleep (the neurons that are targets of anesthetics).   The sleep neurons are active when the organism is tired and needs sleep (it is the result of these neurons being activated that causes sleep), and less active when it is well rested.  The switch or “homeostat” is one of two devices that regulate sleep (the other is the body clock that distinguishes night from day in humans). It records the hours a person is awake and then signals the neurons that cause sleep when the person needs to rest.    

In the study, flies were kept awake all night.  Regular flies slept more the next day, while the mutants could not do this.  The mutants were found to “nod off” (determined by the fact that flies stop moving when they sleep) and were found to have learning and memory issues.  In these mutants, researchers found a key molecular piece of the “sleep switch” and determined that it was broken.  This resulted in the neurons that cause sleep not being activated; this led to insomnia.

Now that the sleep switch has been “pinpointed”, what new drugs will be created to treat insomnia and other sleep disorders?  People are also wondering if this more specific discovery will help answer the larger question of why animals need sleep at all.  As someone who does not get much sleep, I find this new identification very interesting and relevant in the busy lives of people today.

Fruit Fly Fight Club

Everybody knows that males tend to be more aggressive than females.  But why is that the case?


In a recent New York Times article, a study on fly aggression by neuroscientists from the California Institute of Technology revealed that male flies, just like humans, tend to be more aggressive than female flies.  And their findings may provide an insight as to why male humans are more aggressive than female humans.

Doctor David J. Anderson set up a fight club for flies and found out that a tiny cluster of neurons only found in the brain of male fruit flies control aggression.  These neurons, active only when the males were fighting each other, released tachykinin, a neuropeptide linked to aggression                                                                                                                                                                                 .

Humans have a different kind of tachykinin, called substance P, which is associated with inflammatory processes and pain.

The few neurons that caused an increase in aggression in the flies were only found in males.  They found that the levels of aggression in flies is directly associated with the amount of tachyninin produced by the neurons.  From these studies, it appears that humans and flies have more in common than we think.  And the flies can teach us about the neurology of own aggression.




Could it be more than a Simple Physical Attraction?

Ever wonder why there are so many cougars around these days, or so many older men dating younger women?

It’s not just because of a physical attraction. In fact, attraction in humans and in fruit flies relates to pheromones, or “the chemicals of love.” In the recent Biology News article “Fruit Flies Drawn to the Sweet Smell of Youth,” I learned that cuticular hydrocarbons,which are the pheromones of fruit flies, change with age. In an experiment run by Tsung-Han Kuo, a ” a graduate student in the department of molecular and human genetics and the Huffington Center on Aging at BCM,” it was obvious that the male fruit fly was attracted much more to the young female fruit fly than the older female fruit fly. This was even true when the male fruit fly could not see the flies because the scientist had made the room dark. Interestingly enough, all it took for the male fruit fly to be confused about which woman to choose was to wipe the pheromones, or rather the cuticular hydrocarbons, off the bodies of the female fruit flies. When this occurred, the male fruit fly was rather ambivalent and flummoxed with the decision over which fly to choose to mate with. This tells us that pheromonesmake all the difference, an

most significantly to this article, they spark fly attraction. I believe that this pheromone attraction could be the true reason why  many individuals stray from their significant others to find “hotter” and “sexier” partners.


A Dead Fruit Fly.

To sum all this up, based on our experiments in class, we know that fruit flies produce massive numbers of children, and as these female fruit flies age, the male fruit flies that they have mated with in the past are vastly less interested and attracted to the aging female pheromone.

No Drinking Age for Fruit Flies!

Photo Credit: digicla

Why can’t I drink alcohol but a mere fruit fly is able to, you ask? Well unless you wish for wasps to lay their eggs inside you I suggest you drop that argument.

A new article explains what is going on. Fruit flies eat a lot of yeast (which as we know from our studies breaks down sugar and in the process produces alcohol). They do this because a certain kind of wasp actually lays its’ eggs inside of a fruit fly, so that when the eggs hatch the baby wasps can eat the living fly and eventually leave the body when they are grown. Beware because things get more disgusting than that…

To prevent such malicious murder, the flies have a trick of their own. They consume so much yeast that they are considered “drunk”. The alcohol smells so bad to the wasps that not only do they choose to not lay their eggs within that particular fly, but any eggs they do lay meet a very violent end.

Here is where things get worse. In a study done by Dr. Schlenke, wasps were allowed to lay eggs in two flies. One fly was perfectly sober, and one was fed food that had 6% alcohol in it. As I’ve said, more wasps layer their eggs in the sober fly, and less in the drunk fly. However, the eggs that did get laid in the drunk fly did not meet an honorable end. Dr. Schlenke found that 65 percent of the eggs inside of the drunk fly not only died, but died because all of their tiny inside organs had shot out through their anus. At this point I wish that I was not writing about this article, but the show must go on.

It was also discovered by Dr. Schlenke that if a fly ate the alcohol ridden yeast before being violated by the wasps, it made no difference. Such a discovery lead scientists to ponder whether the flies realized the deadly wasps inside of them and so chose to eat the yeast then, in order to kill off the parasite. Further experiments with flies showed that the flies do indeed seek out the alcohol as a self medication to kill off the wasps inside of them.

Smart flies right? Can you believe that this is what fruit flies have to put up with? Or that little tiny flies can get drunk off the alcohol produced by yeast? I, for one, will take a drinking age of 21 any day instead of having tiny wasps live inside me. But thats just me, what do you think?

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