Omicron Variant Defies the Process of Natural Selection

     An article written by Carl Zimmer for the New York Times explores the extreme evolutionary change in the Omicron variant. Variants of the original virus have been surfacing for quite some time, but the Omicron variant is in a league of its own. Zimmer writes, "...earlier variants had differed from the original Wuhan version of the coronavirus by a dozen or two mutations, Omicron had 53." A good number of these mutations were expected to be harmful to the virus, as they were not found in other coronaviruses. In fact, 30 new mutations were discovered in Omicron's spike protein, 13 of which were mutations rarely, or never, found in other versions of the virus. 

    Natural selection selects for traits that increase an organisms fitness in their given environment. If a mutation is beneficial to the virus, it would be rational to believe it would be observed among other variations, such as the Delta variant. Scientists have sequenced millions of coronavirus genomes over the course of the pandemic, but the Omicron variant has mutated in ways to be unlike any of the others. These mutations in its spike protein change the way the virus infects other cells entirely. Instead of the typical way by merging with another cells membrane, the Omicron variants unique spike protein allows the cell to completely engulf it. It then breaks open, infecting the host cell from within. One explanation for the success of the Omicron variant is epistasis. On their own these 13 mutations may have been harmful to the virus, but all the mutations combined just happened to be beneficial. 

    Opinion: How successful these mutations make the Omicron variant is still unclear, but the rate at which the virus is developing these mutations as a whole is mind boggling. 

                                                                                                               - Written by Rachel Roman

Resurrecting Lost Genetics: Cloning Historic Horses to Increase Genetic Diversity in the Przewalski's Horse Population

     

    The Przewalski's horse, also known as Equus przwalskii, has been struggling with extinction for many years. At one point the Przewalski's was believed to be completely extinct in the wild, but conservation efforts have succeeded in reintroducing Przewalski's horses into protected areas in their natural habitat. More information about Przewalski's horses can be found here

    With a population of about 2,000 individuals in captive breeding programs and in protected areas, the Przewalski's horse has been classified as an endangered species, but the Przewalski's horse is beginning to face a different challenge. The Revive & Restore conservation organization, who has been involved in the conservation efforts of Przewalski's horses, explains that the Przewalski's horse population is now suffering from genetic bottlenecking. Genetic bottlenecking commonly occurs when population numbers are low, and it causes a decrease in genetic diversity in the population because of inbreeding. This lack of genetic diversity causes species to be extremely venerable to sudden environmental changes or diseases because they do not have the genetic variation that helps them to adapt to change. 

    The most common solution to this problem is brining unrelated individuals into the population to broaden the gene pool, but for the Przewalski's horse there are not unrelated individuals because all living Przewalski's horses are decedents of 12 individuals that remained when the recovery efforts began. Thanks to modern science, these unrelated individuals do not necessarily need to be living to be introduced into the population. Conservationist had saved living cells from more than a dozen Przewalski's horses and had them cryopreserved, and these cells contain genetics that are no longer found in the current Przewalski's horse population. Scientists are reintroducing these lost genetics by cloning the historic Przewalski's horses using the frozen cells. In 2020 they successfully cloned a past stallion who they have names Kurt, and once Kurt reaches sexual maturity he will be used in breeding and will help to bring more genetic diversity into the population.

    This is not only an amazing feat in science, but it also such an amazing thing to whiteness. I think the cloning of past Przewalski's horses in order to reintroduce lost genetics is spectacular. As someone in the horse community, I have heard both the advantages and disadvantages of equine cloning and the debate over cloning horses, so it brings me great joy to see this scientific advancement be used to assist the Przewalski's horses on their road of population recovery.

Link to the press release from the San Diego Zoo Global (now known as the San Diego Zoo Wildlife Alliance)

Przewalski's Horse Press Release Revive & Restore.pdf - Google Drive

Genetic Differences In Dinoflagellates Could Help Coral-Symbiont Pairs Become More Resilient Against Climate Change

        As climate change increases stress on coral and their symbionts, extinction is on the horizon. Reefs are given shorter and shorter intervals to recover naturally which can be seen most easily as the effect of coral bleaching. The coral bleaching effect is a result of symbiotic dinoflagellate expulsion from the main coral body. The dinoflagellates provide essential nutrient processing to coral bodies, such as photosynthesis, so their expulsion causes the coral to die.
        An article about how Symbiodiniaceae, a genus of dinoflagellate, meets the challenges of life during coral bleaching explains the specific impacts climate change has on the Symbiodinium genome. Symbiodiniaceae first alters at transcriptomic levels potentially mediated by second messenger systems, followed by proteomics and metabolic reprogramming. By pinpointing specific changes and differences among the 7 Symbiodinium clades, identification of stress-specific or stress-independent genes could be utilized for trait improvement using genetic engineering.
        Hope is found in research that is being conducted on the implementation of Type I RuBisCO as opposed to the Type II RuBisCO currently found in Symbiodiniaceae. The Type I RuBisCO found in cyanobacterium provides a more heat-resistant form which will help maintain the rate of the Calvin-Benson Cycle during photosynthesis. Increasing heat resistance will help maintain the integrity of the symbiotic relationship.
        Although genetic engineering is frightening in the sense that it can induce a monoculture, at the rate the planet is heating up, coral reefs are already vulnerable. It is paramount for each variety of genetically engineered coral to maintain a level of genetic diversity to lower its vulnerability to environmental factors not mitigated by targeted genetic alterations. I do not believe that any one genetically modified coral-symbiont combination should be the stopping point. It is only a good first step in preserving biodiversity, so one of the most genetically diverse ecosystems does not cease to exist in the coming years.


What to read next: Thermal tolerance of the hermatypic coral Acropora tenuis elucidated by RGB analysis and expression of heat shock proteins in coral and symbiotic dinoflagellates