AP Biology class blog for discussing current research in Biology

Author: baracatalyst

CRISPR/Cas9, Omnipotent Cure or New Toy for the Rich and Famous?

Editing the human genome has been a highly controversial subject matter in the field of bioethics as advancements with techniques like CRISP/Cas9 allow for precise DNA cutting and sequence addition.  As of February 14th, a panel for the National Academies of Sciences and Medicine concluded that altering DNA in gametic cells is ethical as long as it is only utilized to cure genetic diseases that could be passed down to offspring and not to simply enhance health or certain characteristics.  This is novel as former recommendations given by organizers of a global summit on human gene editing proposed that gene manipulation via molecular scissors should not be used in the production of babies.  However, it is important to note that while the Nation Academies reports often impact policy formation in the United States and around the world, they hold no actually legislative weight and authority rests in hands of Congress, regulatory agencies like the FDA, and both state and local governmental bodies.

Depiction of CRISPR/Cas9 protein complex by Thomas Splettstoesser, source

Some scientists like panel cochair Alta Charo of the University of Wisconsin-Madison Law School are still highly skeptical of heritable gene editing and have not yet pinpointed times when it is just to perform.  “We are not trying to greenlight heritable germline editing,” says Charo, “We’re trying to find that limited set of circumstances where its use is justified by a compelling need and its application is limited to that compelling need.  We’re giving it a yellow light.”  Others hold the notion that any manipulation of the germline will inevitably culminate in the creation of “designer babies”.  In their minds, this could stigmatize disabled people, heighten inequality between the rich and those who can’t afford the treatment, and possibly start a new wave of eugenics like seen in the sci-fi film Gattaca (1997). Marcy Darnovsky, executive director of the Center for Genetics and Society in Berkeley, California, comments, “Once you approve any form of human germline modification you really open the door to all forms.”

On the other end of the spectrum, many are thrilled with the decision and see a bright future for the human race.  Sean Tipton, a spokesman for the American Society for Reproductive Medicine in Washington, D.C., states, “It looks like the possibility of eliminating some genetic diseases is now more than a theoretical option.  That’s what this sets up.” Indeed, debilitating diseases caused by mutations in single genes like cystic fibrosis and Huntington’s could become a thing of the past in the near future.  Unfortunately, genome editing to cure more complex diseases and disorders associated with mutations in multiple genes (autism, schizophrenia, etc.) is still very far in the future.

In reality, there is little to worry about in the area of germline editing for now as panelist Jeffrey Kahn of Johns Hopkins University ensures that the beginning of heritable gene alteration is closed off until requirements can be met at the legislative level.  Additionally, the panel presented numerous obstacles that must be cleared before germline manipulation can become a reality.  Nita Farahany, a bioethicist at Duke Law School claims, “Some people could read into the stringency of the requirements to think that the benefits could never outweigh the risks.”  Also, the requirement to follow up with multiple generations of genetically modified children to study what consequences the therapy holds for future offspring is an invasion of privacy.  Farahany adds that, “You can’t bind your children and grandchildren to agree to be tracked by such studies.”  On top of all this, it is extremely difficult to draw distinctions between therapies and enhancements. George Church, a Harvard University geneticist, remarks that nearly all medical advancements could be considered life-enhancing.  “Vaccines are advancements over our ancestors. If you could tell our ancestors they could walk into a smallpox ward and not even worry about it, that would be a superpower.”

So, where will germline editing take the species Homo sapiens?  Is the cure for cancer on the horizon?  Would the pursuit of creating perfect humans be beneficial or harmful for society?

Guppy Social Circles: The Evolutionary Benefit of Tight-Knit Groups

It is often said that humans are social creatures.  But why is this?  How do other species help substantiate the need for social interaction and friendship among humans?  What direct benefits result from strong ties between individuals?  To grapple with these questions, Rob Heathcote, an animal behavior researcher at the University of Exeter, conducted the following experiment.

Guppies swimming in a group of three by Per Harald Olsen, source

Heathcote and his team traveled to Trinidad, an island in the Caribbean that is home to the small freshwater Trinidadian guppy.  But why this place and this species you might be asking.  In response, Heathcote states that, “These guppies live in environments that have tons of predators around, so basically it really sucks to be a guppy. In some places they live, you’ll be watching these shoals of guppies and a predator is attacking them every twenty or thirty seconds or so.”  With the hypothesis that animals form social groups in order to reduce the risk of being preyed upon, the Trinidadian guppy was the perfect specimen.  However, Heathcote sought to investigate whether the benefits of communal living derived from individual relationships (as in humans) or simply safety in numbers.

The team divided 240 female Trinidadian guppies into smaller groups of fifteen, with each group having its own pool isolated from the rest.  Some fish were left alone while others were spooked with a doll version of a predator known as the pike cichlid.  It was recorded that the groups formed by the guppies exposed to the faux predator were smaller on average when compared to the groups that the unprovoked fish formed.  Therefore, one can conclude that the startled guppies fearing for their lives were more likely to establish stronger social connections between one another.  In other words “Fear of predation drives stable and differentiated social relationships in guppies” (Heathcote et al. in Scientific Reports).

So, guppies can congregate in massive groups to blend and reduce their chances of becoming dinner.  However, congregation itself attracts more and more predators.  Alternatively, as seen in the experimentation, they can hide in smaller social circles of three to four individuals, a sort of family where each guppy has each other’s best interest in mind and where the guppies can effectively communicate.  When drawing parallels between the Trinidadian guppy and humans, it is clear that both species form exclusive clans to ameliorate their lives.  In the words of Jason G. Goldman, “Spending time with a few close friends could outweigh the benefits of blending in with the crowd, particularly in dangerous situations.”

The research results in many follow up questions.  Why do some humans choose to isolate themselves from social interaction altogether?  How can this study relate to international relations?  What really makes humans different from more primitive species?

No More Lactase Pills?!

Love milk, yogurt, pizza, and other irresistible dairy products?  Hate having to take lactase pills or face suffering in the bathroom every time after you eat or drink them?  You’re not alone. In fact, it is estimated that around 75% of the entire human population has difficulty absorbing lactose, or the sugar found in milk and dairy products. However, a recent revelation has suggested a way to manipulate the human gut microbiome and circumvent this issue.

Bifidobacteria in human gut microbiome

In a study conducted by Dr. Andrea Azcarate-Peril, an Assistant Professor of Medicine in the School of Medicine at UNC Chapel Hill, it was shown that highly purified (>95%) galactooligosaccharides could indeed improve or often eliminate the indigestion (nausea, cramps, bloating, etc.) felt by lactose-intolerant subjects. To investigate this finding, Azcarate-Peril and her team conducted the following experimentation.

Human subjects were administered the high-purity short-chain GOS, designated as “RP-G28”, and stool samples were collected at three separate times: pretreatment (day 0), post-treatment (day 36), and after the GOS feeding was halted and the subject was encouraged to consume dairy products (day 66).  To analyze changes within the fecal microbiome, scientists used 16s rRNA amplicon pyrosequencing and high-throughput quantitative PCR.  Samples from day 36 saw an increase in bifidobacterial populations in 27 out of the 30 subjects (90%).  This confirmed that GOS resulted in a bifidogenic response in vivo.  Additionally,  GOS induced a significant increase in the relative amount of lactose-fermenting Facecalibacterium and Lactobacillus.  Then, when dairy was introduced into the subjects’ diets (day 36 to day 66), lactose-fermenting Roseburia species presence increased.  In conclusion, the results of Azcarate-Peril’s work indicate that a GOS diet can cause a definitive change in the fecal microbiome of a lactose-intolerant individual, increasing concentrations of a lactose-metabolizing bacteria.  The change discovered has been correlated with improved lactose tolerance in patients at the clinical level.

We might be on the verge of helping millions upon millions of people who are lactose malabsorbers!  As an individual who struggles with lactose intolerance, this is fantastic news and I cannot wait for more research to be conducted in this domain.  What other gastrointestinal issues could we solve by affecting the human gut microbiome?  Are we on the road to curing inflammatory bowl disease (primarily ulcerative colitis and Crohn’s disease)?


Mirror Mirror On The Wall, Can Animals Recognize Themselves At All?

Eat. Drink. Excrete. Sleep. Repeat.

We humans often reduce the lives of animals to these common processes. However, scientists in recent decades have broadened the horizons for animals by looking into their ability to self-recognize.

Developed in 1970 by psychologist Gordon Gallup Jr., the mirror self-recognition (MSR) test has been the most common method of testing animals’ awareness of themselves.  The test entails the placement of a red spot on a sedated animal in a location which the animal cannot see without a mirror.  The spot must be smooth and odorless as to not excite any olfactory or tactile cues. Once the sedation wares off, the animal is presented with a mirror.  If the animal makes a movement towards the red spot, the test makes the assumption that the animal recognizes itself.  Most species tested have failed the MSR exam with only great apes, an individual Asiatic elephant, orcas, dolphins, and Eurasian magpies passing as of 2016.

The mirror test - a Baboon looking at at his own reflection

Baboon observing itself during MSR test by Moshe Blank, source

However, the “red spot” test has come under scrutiny with many scientists claiming that it is not a true indicator of self-recognition.  For the exam to be applicable, one must make the assumption that animals know the reflective properties of a mirror, an object which they may have never seen before. Additionally, many animals (especially wild one’s) do not have a clue as to what they look like as an individual. Rather than visuals, they can often recognize certain smells and sounds. Marc Bekoff, professor emeritus of ecology and evolutionary biology at the University of Colorado Boulder, conducted “yellow snow” experiments in which he deducted that his dog Jhetro could recognize its own urine and would respond differently when presented with the urine of other dogs.  “Animals such as Jethro may fail the red dot test but still possess some sense of self or ownership over their body and smells.”

Strengthening the case against the MSR test, naturalist legend Charles Darwin claimed in his theory on evolutionary continuity that the differences among species come in degree, not kind.  This means that if humans are self-aware creatures, other animals are most likely self-aware as well but to a different extent.

Although animals may not have the same reaction when looking into a mirror as humans do, most creatures understand that they possess their own body which does not belong to another.  For example, animals must know the placement of their bodies in space to effectively navigate as a pack or flock. Lastly, one can look to his/her four-legged friend on the floor to see how animals display ownership over food, territory, family, and body parts with which they associate.

So, can animals really recognize themselves?  Yes, they can.  Just not always in the same ways humans do.

This area of research opens up the gates to even more complicated questions about animals.  How do different species think and feel? How do they grapple with emotion?

Dolly’s Legacy and the Healthy State of Sheep Clones

Over the past two decades, there has been much discussion around Dolly in the scientific community.  No, not Dolly Parton (although her name served as an inspiration), but Dolly the cloned sheep.  In 1996, researchers at the Roslin Institute, an animal sciences research center at the University of Edinburgh, made history by cloning the first mammal from an adult somatic cell via nuclear transfer.  The cell utilized for the cloning was from a mammary gland, and Dolly’s successful birth and 6 year longevity signified that cells other than gametes and germ cells could recreate an organism.  However, scientists and laymen alike have expressed concern regarding Dolly’s short lifespan in respective to the overage sheep’s of 10-12 years.  Does this mean clones are unhealthier versions of their “natural” predecessors?

dolly_face_closeupPhoto of Dolly’s taxidermied remains by Toni Barros, source

According to research conducted by Kevin Sinclair of the University of Nottingham, the answer is no.  Monitoring four sheep derived from the same mammary gland cells as Dolly in addition to nine cloned sheep of other breeds, Sinclair has dug up no evidence to suggest that the clones are less healthy than sheep born of natural processes.  In fact, all 13 of the sheep are now older than nine (equivalent to 70 or 80 years in the lifespan of a human) and are as healthy as their non-cloned counterparts according to tests scanning their bones, blood glucose levels, and blood pressure.

And so the question is posed, why did Dolly die young?  Scientists who interacted with Dolly claim that her life was taken by a contagious illness that ravaged the flock- not some defect as a result of her being a clone.  To address Dolly’s severe amounts of arthritis at the time of her death, geneticist Helen Sang from the Roslin Institute points to her indoor captivity and the excessive amounts of treats she was given.

While cloning might not be as efficient as traditional modes of breeding, this study exhibits that cloned animals which survive gestation and are relatively healthy during their infancy have the same chances of thriving and living to expected longevity as any other animal of the breed.  Additionally, cloning allows scientists to generate embryonic stem cells for further scientific research and to produce “high-value livestock”.  These advantages begin to show the importance of clowning and how beneficial it can become if it is accepted as an integral part of scientific studies. What animals are next to be cloned?  What impacts would cloning humans have on our society?

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