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When ultraviolet sunlight hits our skin, it affects each of us differently. Depending on skin color, it'll take only minutes of exposure to turn one person beetroot-pink, while another requires hours to experience the slightest change. What's to account for that difference, and how did our skin come to take on so many different hues to begin with? Angela Koine Flynn describes the science of skin color.

This directed case study examines differences between the exponential and logistic growth models in biology and how they are applied to solve real life problems. The narrative follows a student returning to the United States as he tries to assess his possible exposure to Middle East Respiratory Syndrome (MERS). To better understand his risk, James needs to get up to speed on a variety of topics including the difference between infection, transmission, virulence, etc., and how these topics can be mathematically modeled not only in relation to MERS, but also with respect to Ebola and influenza. This case was designed for use in the second semester of a biocalculus course or a course involving ordinary differential equations, which are appropriate for second year undergraduate students majoring in biology, pre-med, and bio-mathematics. These students typically have completed a semester of calculus and one year of general biology. The case provides an opportunity for students to develop their understanding of differential equations and increase their appreciation of mathematics as it applies to solving a problem of biology.

Why is the North American population of monarch butterflies declining? In 1999, a study published in the journal Nature suggested that a variety of genetically modified corn was killing these iconic butterflies. While it was later shown that the conditions in this study did not mirror those in the field, the results garnered a lot of media attention and many people today still believe that monarchs are being killed by GMOs. This case familiarizes students with the plight of the monarchs, encourages them to think about how to test the hypothesis that a toxin is responsible for their decline, and takes a critical look at several studies that investigated the role of Bt corn in the life cycle of monarchs. This interrupted case takes 60-90 min to complete, requires little to no science background, and can be used to explore the ecology and wildlife management of monarchs; risk assessment, toxicity, and exposure; experimental design, the scientific method, hypothesis, and critical thinking; or the relationship between science, the media and the public.

Pharmacogenomics can play an important role in identifying responders and non-responders to medications, avoiding adverse events, and optimizing drug dose. Drug labeling may contain information on genomic biomarkers and can describe: Drug exposure and clinical response variability Risk for adverse events Genotype-specific dosing Mechanisms of drug action Polymorphic drug target and disposition genes The table below lists FDA-approved drugs with pharmacogenomic information in their labeling. The labeling for some, but not all, of the products includes specific actions to be taken based on the biomarker information. Pharmacogenomic information can appear in different sections of the labeling depending on the actions. For more information, please refer to the appropriate labeling guidance.

Why did you get the flu this winter, but your co-workers didn't? The answer, according to a new study of twins, may have less to do with your genes and more to do with your environment-including your past exposure to pathogens and vaccines. Our immune system is incredibly complex, with diverse armies of white blood cells and signal-sending proteins coursing through our veins, ready to mount an attack on would-be invaders. Everyone's immune system is slightly different-a unique mixture of hundreds of these cells and proteins. But the main driver of this variation is unclear. Although scientists know that our immune system can adapt to our environment-that's why vaccines work, for instance-it is also built by our genes.

Gregory Lanzaro, medical entomologist and professor at University of California Davis (UC Davis) and leader of the research team behind the discovery, says they are calling the hybrid mosquito a "super" mosquito because it can survive exposure to the insecticides used to treat bed nets. He and his team report their findings in the Proceedings of the National Academy of Sciences.

HIV is a disease of the gut, a concept that's easy to lose sight of with all the attention paid to sexual transmission and blood measurements of the virus and the CD4+ T cells it infects and kills. But the bottom line is that about two thirds of all T cells reside in the lymphoid tissue of the gut, where the virus spreads after exposure, even before it shows up in blood.

In July, the AP reported that its first round of tests showed disease-causing viruses directly linked to human sewage at levels up to 1.7 million times what would be considered highly alarming in the U.S. or Europe. Experts said athletes were competing in the viral equivalent of raw sewage and exposure to dangerous health risks almost certain. The results sent shockwaves through the global athletic community, with sports officials pledging to do their own viral testing to ensure the waters were safe for competition in next year's games. Those promises took on further urgency in August, after pre-Olympic rowing and sailing events in Rio led to illnesses among athletes nearly double the acceptable limit in the U.S. for swimmers in recreational waters.

IN recent weeks, two major medical organizations have issued independent warnings about toxic chemicals in products all around us. Unregulated substances, they say, are sometimes linked to breast and prostate cancer, genital deformities, obesity, diabetes and infertility. "Widespread exposure to toxic environmental chemicals threatens healthy human reproduction," the International Federation of Gynecology and Obstetrics warned in a landmark statement last month.

This case study presents a realistic example of drinking water contamination within a fictional local community and leads students through an abbreviated human health risk assessment. Students are provided background information about the extent of the contamination and a description of the contaminated site and are then required to calculate both the cancer and non-cancer risks to the community. This exercise is appropriate for an environmental toxicology or environmental risk assessment course. It works well after a lecture on the basics of risk assessment including how to calculate exposure intakes and risk estimates.

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