AP Biology class blog for discussing current research in Biology

Author: vonstadenine

CRISPR/Cas9: A New Means to Alter Genes

Biologists can now control genetic inheritance in mammals with a CRISPR/Cas9-based approach, which allows geneticists to alter parts of the genome by removing, adding or altering sections of the DNA sequence.  Scientists have sought a way to make precise changes to the genome of living cells for a long time, and now they actually can. You may ask, what are CRISPR and CAS9? Why are they important? Simply put, “The functions of CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) and CRISPR-associated (Cas) genes are essential in adaptive immunity in select bacteria and archaea, enabling the organisms to respond to and eliminate invading genetic material.”  Thus, this recent discovery has created the groundwork for developing new ways to fight diseases. UC San Diego researchers are responsible for this breakthrough. First, they injected a mouse with an engineered active genetic “CopyCat” DNA element into a Tyroisinase gene. The Tyroisinase gene determines fur color. The CopyCat element “disrupts” both copies of the Tyroisinase gene, causing the mouse to have white fur instead of black. The CopyCat element, however, could not spread through a population by itself, unlike the CRISPR/Cas9 systems, which could. This approach, though, was effective only in female mice, not in male ones, likely because of timing differences in meiosis – “a process that normally pairs chromosomes to shuffle the genome and may assist this engineered copying event.” The findings are nonetheless a success. Scientists are optimistic they will be able to alter multiple genes and traits using the same techniques in the near future. Cooper, one of the researches, summed up their achievement nicely: “We’ve shown that we can convert one genotype from heterozygous to homozygous. Now we want to see if we can efficiently control the inheritance of three genes in an animal. If this can be implemented for multiple genes at once, it could revolutionize mouse genetics,” said Cooper. More importantly, these findings continue to speed up research into diseases like cancer and mental illness.

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CRISPR-CAS9 — “How the genome editor works”

Melting Glaciers & Rising Sea Levels

Because of ocean warming and melting of land ice, sea levels have risen all over the world. However, sea levels have not risen by the same amount everywhere. Along the coast of North Carolina, for example, the sea level has risen by about 18 inches (a foot and a half). Along Miami and New York City, the sea has risen by approximately 12 inches. And in Portland Maine, the sea has only risen by 6 inches. According to a study done by the Woods Hole Oceanographic Institution (WHOI), these variations can be attributed to a “post-glacial rebound.”

Image result for picture of the ocean“View of the ocean from Zamami Island, Okinawa, Japan. October 2015.”

In short, during the most recent Ice Age, Canada and parts of the Northeast United States were covered by colossal “sheets of ice.” The immense weight of the ice caused the land to sink. Areas on the periphery of these ice sheets, however, began to rise. Once the ice sheets began to melt approximately 26, 500 years ago, the “weighed-down” land gradually rose, whereas the peripheral lands started to sink. The ice sheets melted away about 7,000 years ago, but this “post-glacial rebound” is still taking place.

File:Icebergs.jpgIcebergs | St. Anthony, Newfoundland

The lead author of a study published in the journal Nature, Chris Piecuch, wanted to determine why sea levels rose at quicker rate in certain areas during the last century. He and his colleagues used advanced technology to take sea level measurements and combined “observational data with complex geophysical models — something that has not been done before — to give a more complete view of sea level changes since 1900.” The team ultimately determined that most of the sea level changes have been due to “post-glacial rebound,” and that “sea level trends increased steadily from Maine all the way down to Florida.” Pieuch attributes these changes to groundwater extraction, as well as to more recent melting of glaciers and ice sheets. These occurrences can cause masses of water around the Earth to move, and affect the planets crust. Although Piecuch is uncertain as to why water is redistributed to certain locations, he is pleased with his findings, stating: “Post-glacial rebound is definitely the most important process causing spatial differences in sea level rise on the U.S. East Coast over the last century. And since that process plays out over millennia, we’re confident projecting its influence centuries into the future.”


Genetic Engineering will Create Super Humans?!

“Synthetic microbiome? Genetic engineering allows different species of bacteria to communicate”

Before seeking to analyze how genetic engineering enables the alteration of the microbiome, it is essential to understand the nature of the microbiome. Humans’ microbiomes consist of “trillions of microorganisms (also called microbiota or microbes) of thousands of different species.” Initially, peoples’ microbiomes are solely determined by their DNA; however, as time goes on, a person’s microbiome can be shaped by other factors, including the environment in which they live, or their diet. The microbiome contains both helpful and deleterious microbes, but “In a healthy body, pathogenic and symbiotic microbiata coexist without problem.”

According to researchers from the Wyss Institute at Harvard University, Harvard Medical School (HMS), and Brigham and Women’s Hospital, it may now be possible to create a “synthetic microbiome.” The team did a study in which they utilized a particular type of quorum sensing known as acyl-homoserine lactone sensing. Quorum sensing allows bacteria to regulate the expression of genes and to detect the size of bacterial colonies, through signal molecules. First, the team inserted “two new genetic circuits into different colonies of a strain of E. coli bacteria.” One of the circuits acted as a “signaler” and the other acted as a “responder.”

File:E. coli Bacteria (16578744517).jpg Picture of E. Coli bacteria

In short, the team inserted a single copy of luxl, a gene activated by the molecule anhydrotetracycline (ATC), into the signaling circuit. The signaling molecule formed by this gene then binded to the receptor circuit, which activated another gene, known as cro. The cro gene creates Cro proteins, and these proteins triggered a “memory element” within the responder circuit, in which two more genes, LacZ and another cro, were produced. If the signaling molecule is received (which it was), the presence of LacZ causes the bacterium to turn blue. Most importantly, the additional cro gene essentially keeps the “memory element” on, so this cycle continues.

To make sure that this system works in living organisms, the researchers tested it in mice. Signs of signal transmission in the mouse’s gut between the signaler S. Typhimurium bacteria and E. coli responder bacteria were detected. In other words, the engineered circuits allowed the bacteria to communicate with one another.

While these findings are extremely exciting, scientists have yet to discover whether or not other genetically engineered species of bacteria will also be able to facilitate communication between molecules. A Founding Core Faculty member of the Wyss Institute said that “[They] aim to create a synthetic microbiome with completely or mostly engineered bacteria species in our gut, each of which has a specialized function.” If this is achieved, we will move one step closer to becoming super humans!

Feature Image: “Free for Commercial Use” and “No attribution required”

Don’t be Amoral… Help Rehabilitate the Coral!

The Rehabilitation of Coral Reefs with “Spiders”

Coral reefs have recently been decimated worldwide. While there have been countless efforts to rehabilitate damaged coral reefs, very few have been successful, up until now.

According to a study “led by the University of California, Davis, in partnership with Mars Symbioscience,” there is a new, relatively inexpensive technique that utilizes “spiders” – hexagonal, “three-and-a-half square ft. structures made from rust-protected reinforcing steel rods” – to facilitate the renewal of coral reefs. In order to test the effectiveness of this technique, researchers traveled to Indonesia’s Coral Triangle, a region possessing the greatest coral diversity in the world. As expansive as it is, the region is a skeleton of its former self. There, the researchers fixed 11,000 “spiders” onto 5 acres of reef, starting in 2013. The transformation of the reef was astonishing. Apparently, “Live coral cover on the structures increased from less than 10 percent to more than 60 percent.” Furthermore, while coral bleaching devastated entire reefs in various locations worldwide between 2014-2016, it had minimal effects (less than 5 percent) on the rehabilitated reefs. As Frank Mars, the vice president of Mars Sustainable Solutions, stated, healthy coral reef ecosystems are not only essential to the environment and the well-being of all people, but also provide economical opportunities, by providing a “foundation for many local fisheries, as well as jobs for tourism.”

diving underwater biology seaweed blue colorful coral coral reef invertebrate clown fish reef nemo turquoise algae creature beautiful exotic anemone meeresbewohner organism sea anemone marine biology coral reef fish marine invertebrates pomacentridae freshwater aquarium

“The image is released free of copyrights under Creative Commons CC0.”                                                       Taken by an “unknown lens”

While this news is very promising for the future, more still should be done. Human activities, such as illegal fishing and pollution, have to be better controlled, and their negative impact mitigated as much as possible. Also, more people have to be educated about the enormous adverse impact of their actions on the ocean environment. “In the meantime, the ‘spider’ technique and restoration projects offer a way to rehabilitate large swaths of coral reefs and the communities that depend on them, giving the reefs a chance to adapt or acclimate to worsening ocean conditions.”

Feature Image: Taken by Jan-Mallander


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