Potent marine neurotoxins known as brevetoxins are produced by the 'red tide' dinoflagellate Karenia brevis. They kill large numbers of fish and cause illness in humans who ingest toxic filter-feeding shellfish or inhale toxic aerosols 1 . The toxins are also suspected of having been involved in events in which many manatees and dolphins died, but this has usually not been verified owing to limited confirmation of toxin exposure, unexplained intoxication mechanisms and complicating pathologies 2-4 . Here we show that fish and seagrass can accumulate high concentrations of brevetoxins and that these have acted as toxin vectors during recent deaths of dolphins and manatees, respectively. Our results challenge claims that the deleterious effects of a brevetoxin on fish (ichthyotoxicity) preclude its accumulation in live fish, and they reveal a new vector mechanism for brevetoxin spread through food webs that poses a threat to upper trophic levels.In the spring of 2002, 34 endangered Florida manatees (Trichechus manatus latirostris) died in southwest Florida, and 107 bottlenose dolphins (Tursiops truncatus) died in waters off the Florida panhandle in the spring of 2004. In both of these unusual mortality events, extensive water surveys revealed that only low concentrations of K. brevis were present.We tested for the presence of brevetoxin in the fluids and tissues of 63 of these animals (27 manatees, 36 dolphins) and found very high concentrations in the tissues of all of them (see Supplementary information accompanies this communication on Nature's website.
A series of small literature activities were designed and implemented in a General Chemistry Lab course in an attempt not only to improve students' ability to navigate and utilize the scientific literature but also to affect their self-perceptions of their identification with the scientific discourse community. Selfperceptions were assessed using a pre-and postactivity survey. 67 students participated in the activities which involved a weekly article related to that week's lab topic. Students completed short worksheets with questions that guided them to key ideas and concepts in the articles. In addition to information retrieval, a particular emphasis was placed on identifying the authors and considering the contexts in which the research was carried out. The results indicate that students' self-perceptions regarding their (1) identification with the scientific discourse community and ability to (2) identify the community to which the authors belong, (3) retrieve information, (4) identify the research's purpose, and (5) distinguish data from authors' interpretations all significantly improved.
Isotopic labeling has been and continues to be important in metabolic studies. In this experiment, a heavy isotope of carbon, 13 C, is used to label the product of the well-known RuBisCO enzymatic reaction. This is a key reaction in photosynthesis that converts inorganic carbon to organic carbon; a process called carbon fixation. The biochemicals and 13 C-labeled bicarbonate are readily available. The use of 13 C-label avoids the safety and disposal problems of using radioactive labels. Also, the major instrument required, gas chromatograph-mass spectrometer (GC-MS), is commonly available to undergraduates. So, even though this is a sophisticated laboratory experience for advanced students, it is very feasible in the undergraduate laboratory.This laboratory project exposes students to a number of important concepts and techniques. In addition to learning about isotopic labeling, students are exposed to solid-phase extraction, silylation, gas chromatography, mass spectrometry, and the interpretation of mass spectra. We typically allow two laboratory periods for this experiment and students work in pairs.
America's growing elderly population has led to an increase in research on the aging process, including the relationship of muscle retention to health. Monitoring muscle development at the molecular level is an excellent complement to traditional whole‐muscle assessment methods. 3‐Methylhistidine (3‐MH) is an amino acid derivative and breakdown product of muscle protein. Urinary 3‐MH levels vary with diet and exercise, meriting its use as a molecular marker of muscle turnover. A method to perform rapid quantitation of 3‐MH in urine was developed using single‐ion monitoring (SIM) LC‐MS. After being spiked with an added internal standard and desalted by solid‐phase extraction, samples were analyzed by SIM LC‐MS, quantified versus the added internal standard and normalized versus a ubiquitous internal standard, creatinine. The use of LC‐MS eliminates the need for derivatization as required in established HPLC fluorescence and GC‐MS techniques. Constructed calibration curves plotting the ratio of 3‐MH to internal standard show a strong linear relationship with 3‐MH concentrations, with R‐squared values as high as 0.9983. The method presented is not only effective for monitoring 3‐MH, but holds potential for simultaneous monitoring of additional urine metabolites with run times of approximately 13 minutes.
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