It was not a story typically seen on television. It was not the story of the three musketeers told in the salamander persona. It was a story of an isolated population, when they were ready to leave home, and the decision of choosing a mate. On March 9, 2017, Dr. Derek Girman, from the Department of Biology at Sonoma State University presented his research on these amphibians at the Piner High STEM cafe.
The first case discussed how populations become individual species which for these animals that do not travel big distances- seems to rely on local geological events. He discussed how allotropic isolation which is caused by land barriers was responsible for creating two distinct populations of the California Giant Salamander. About two million years ago the California Giant Salamander broke in two separate populations as the Sacramento river drained to the ocean and create the San Francisco Bay. The root of Dr. Girman’s research was to determine if the two populations had a healthy genetic diversity. It was fascinating to learn about electroshocking ponds to make it easier to catch the salamanders and how he would analyze their DNA extracted from their mitochondria. What was concluded were that there were actually three distinct populations. How this was able to occur was due to prezygotic isolation, the Wilson Grove formation in Mt. Tamailpais and Sonoma County, and the Petaluma Gap (a phenomenon where there is a constant movement of air between regions). In all of the locations sampled there was a healthy genetic diversity except those in Sierra Azul. Here the salamanders looked dry and unhealthy. The cause of this is unknown, but it should be a concern. Was it due to the close mercury mine? Who knows, but further research should be conducted to figure out how we as people from California can protect our indigenous species.
The next scenario was about the California Tiger Salamander and what influences them to leave their birthplace. The eggs of the California Tiger Salamander are found in vernal pools (wetland depressions that fill in rainy season). After the larvae complete their underwater development then they must undergo metamorphosis in order to leave the pools and spend their adult life on land. Once on land, they take residence in squirrel burrows. When they detect a change in air moisture level the salamanders know that it is time for rain and; thus, must lay their eggs. Because seasons are vital to the life span of vernal pools the change of rainy seasons to a dry season was an evolutionary factor that allowed the salamanders to change and adapt from water to land. The change in their shape is a factor that determines survival in their environment and, thus, the question that spurred this research was: what affects the timing of metamorphosis? There are several various factors that make contributions, but the best way to find an answer was to estimate the events of metamorphosis. Dr. German and his research team measured the largest larvae in each pool each week. If there was a decrease in growth size, then the largest larvae have either stopped growing or have already left making the largest larvae in the water slightly smaller. In conclusion to the experiment, Dr. Girman and his team determined that prey density, predator density, and population numbers are not factors to metamorphosis. Evidence suggested that metamorphosis is related to the drop of pool depth. When the depth decreases metamorphosis increases due to the beginning of the dry season. If the depth increases then the pressure to change is less urgent. This demonstrates phenotypic plasticity or an organism's ability to adjust to the environmental conditions.
The third case of salamander biology involved newts. They are a different species from the salamanders, but they do have similar reproductive cycles. The main reproductive difference is that they undergo amplexus where the male grabs the female for reproduction, then he would drop a sperm packet and if she is interested the female will bury her eggs in it. The question that drove the research was: how do newts find their mates? The study revolved around the California Newt, the Rough-Skinned Newt, and the Red-Bellied Newt that all reside in Sonoma county. Due to reproductive isolation these three species do not hybridize with each other. These mechanisms that prevent reproduction are temporal and habitat isolation. Prior research indicated that newts do not use visual stimuli in choosing mates, but do they use chemical signals? The research was done in the Galbreath Wildland Preserve where all three species overlap. Based on what was known, Dr. Girman and his team hypothesized whether smell was a possibility. The experiment was done by leaving individuals to decide who their mates are in a controlled environment. After many trials using Y mazes with different scents applied to each branch, the data indicated that Rough- Skinned females did not have a preference for males of their own species but had a definite aversion to males from other species. When given the option between their own males or water they choose water 50% of the time. In contrast, males would choose any scent that was female regardless of species. Because of this they drive the mating process. Females are, thus, given the responsibility of installing a reproductive barrier between species to prevent hybridization.
If newts choose a mate based on smell, do humans do the same? In the after cafe there was an activity where 12 individuals were given cologne samples and based on their smelling abilities were given the task to find their partner with the same scent. After a few minutes of sniffing each other's card, they all failed to find their correct partner. This showed us that despite what we were supposed to do we tended to choose the smell that appealed to us the most.
Dr. Girman taught the Piner community that protecting these unique animals is important. Many of them are endangered due to the destruction of vernal pools. It is our duty to protect their habitat and rebuild the homes we have destroyed to ensure the future of our diverse, independent, and picky salamanders and newts.
By: Lindsey Tah- STEAM Club President
The classic board game of Monopoly was the focus that Dr. Martha Shott, ( SSU Professor in Mathematics & Statistics) selected to take her audiences through complicated calculations of probabilities. She introduced the concept of Markov chains that take simple statistics such as the roll of a dice to predict where you might end up on the board - no surprise that combinations of 7 were most popular. Then it got complicated as she explained it’s just as important to consider the options one has of landing on the 40 or so spaces on a monopoly board. This required a new statistical tool, called a Stochastic Matrix that had 42 rows and 42 columns. Just taking a look at the diagram was mind blowing but it did prove that we spend most of our time in JAIL ( 6.5%) ! Really not that surprising once you start to analyze the plethora of ways that you can end up in jail - doubles 3x, community chest etc. As the analysis progressed we learned that the orange and red properties get the most landings per game with Illinois being one of the most profitable and those seductive blue deeds such as Boardwalk and Park Place are not a good investment at all. ( see powerpoint for more results)
In our after cafe we did our best to apply these probabilities to our own game boards that had 15 squares. We would place our point values at the most likely places to land on and pitted our board arrangement against our table mates to see who would acquire 50 points first.
Everyone had a good time while we munched on decorated dice cupcakes from the Piner Culinary team ! Not only can we appreciate how mathematical models can manipulate incredible sets of data we all felt better equipped to obtain millionaire status the next time we play Monopoly !
The answer is YES! Humans and yeasts have a compatibility of 30%. As Dr. Chong He presented in the last Stem Cafe, The Fountain of Youth is a Myth- or is it?, having a slightly similar genome can lead to scientific discoveries that might prolong life.
Dr. Chong He studied in China, obtaining a Bachelor's degree in both biology and chemistry. She later went on to complete her Phd in drug design, with the goal of reducing the risks of inflammatory drugs. Dr. Chong He has been working for the Buck Institute of Age Research for a total of 4 years and has made some incredible conclusions based on her research with yeast.
Yeast among many other animals are used as models in research. Why yeast? Well, yeast are unicellular eukaryotic organisms that live for about 25-26 cell divisions, each 1-1 ½ hours long. Yeast is also selected due to its small genome. Lastly as stated in Dr, Chong He’s article, “ a large portion of genes in yeast have been shown to have similar genes in higher eukaryotes that have been implicated in aging related diseases, such as Alzheimer’s disease, Parkinson's disease, Huntington’s disease and cancer.” This similarity led to the scientists collaborating on this research project to as the question, if any drugs could be found that would change the cell cycle properties of yeast to make them have live longer.
The research began by selecting 14 FDA approved drugs that included ibuprofen. The research that began in 2013 finally gave them results. The yeast was injected with the same concentration of ibuprofen as humans, 200mg. “Ibuprofen extends replicative lifespan by about 17% in yeast.” The yeast cells that had been treated with ibuprofen divided a bit over 30 times compared to their normal lifespan of 25-26 divisions. The result of having a longer lifespan was also seen in the worms and the fruit flies.
How does ibuprofen extend lifespan? Ibuprofen extends longevity of yeast by preventing the amino acid tryptophan from entering the cell’s plasma membrane. Ibuprofen also makes cells divide slower, therefore postponing death. This led more research projects that included the drug Rapamycin, found in Chile and used to suppress the immune system. This drug was tested in mice and was found to extend lifespans as well. This drug was also tested on dogs, which resulted in an improved heart rate and function. Along with this the project Antagonistic Pleiotropy proposed a thought that perhaps a gene or hormone was necessary when developing but the case of age once a person reached an older age. Dr. Cynthia Kenyon of UCSF experimented with worms and discovered that worms that didn’t have a growth hormone present has a longer life. Her results brought the idea that maybe the growth hormones are unnecessary once a person reaches their senior years.
The key to a longer and healthier lifespan has been and will continue to be a nutritious diet and exercise. Although conclusions have been drawn that ibuprofen extends lifespans, in yeast, there is still a large amount of research necessary to prove this in humans. The next step would be testing on HeLa cells, a topic being studied by the majority of sophomores at Piner, to conclude that ibuprofen is indeed an anti-aging mechanism.
By: Maria Guzman