Scientific inquiry

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Scientific inquiry

  1. 1. Putting Biologyinto some context
  2. 2. ScientificInquiry
  3. 3. 1.5 - 1.8,0.3 - 0.4
  4. 4. ScientificInquiry
  5. 5. Comparingthoughtswith reality
  6. 6. 1, 1, 2, 3, 5, 8, •••
  7. 7. InductiveReasoning
  8. 8. Specific to General
  9. 9. 1, 2, 4, 8, 16, •••
  10. 10. 1, 1, 2, 3, 5, 8, •••
  11. 11. DeductiveReasoning
  12. 12. General to Specific
  13. 13. Forensics
  14. 14. TheScientificProcess
  15. 15. A templatefor learning aboutthe physical world
  16. 16. Observation
  17. 17. LookListenSmellTouch(Taste)
  18. 18. Hypothesis
  19. 19. Hypothesesmust befalsifiable
  20. 20. Absence of evidenceisn’tevidence of absence.
  21. 21. The Black Swan
  22. 22. Scientific findings should beindependently verifiable
  23. 23. Water boils at100C at 1atmfor everyone
  24. 24. Atrazine
  25. 25. HerbicideWidely usedInexpensiveIncreases yields 1-6%
  26. 26. Tyrone Hayeshttp://www.nationalgeographic.com/field/explorers/tyrone-hayes.html
  27. 27. How would you figure outif Atrazine has any effect on frogs?
  28. 28. Make Observations Form HypothesesPerform Experiments Analyze Data ???
  29. 29. Dissemination ofScientific Findings
  30. 30. Kinds ofSources
  31. 31. Primary Sourcespublish original researchScholarly journal articles, dissertations
  32. 32. Secondary Sourcesrefer to, review, comment on or critiqueprimary sourcesPopular press articles, textbooks,encyclopedias, science books
  33. 33. ScientificJournals
  34. 34. Articles in scientific journals are...submitted by researchers,considered by editors andpeer-reviewed.
  35. 35. Hermaphroditic, demasculinized frogs after exposureto the herbicide atrazine at low ecologicallyrelevant dosesTyrone B. Hayes*, Atif Collins, Melissa Lee, Magdelena Mendoza, Nigel Noriega, A. Ali Stuart, and Aaron VonkLaboratory for Integrative Studies in Amphibian Biology, Group in Endocrinology, Museum of Vertebrate Zoology, Department of Integrative Biology,University of California, Berkeley, CA 94720-3140Communicated by David B. Wake, University of California, Berkeley, CA, March 1, 2002 (received for review December 20, 2001)Atrazine is the most commonly used herbicide in the U.S. and human choriogonadotropin (1,000 international units) 6 h beforeprobably the world. It can be present at several parts per million in harvesting gametes. Eggs were manually stripped from theagricultural runoff and can reach 40 parts per billion (ppb) in female and fertilized in vitro in 0.3 modified mammalianprecipitation. We examined the effects of atrazine on sexual Ringer’s solution by using the sperm obtained from the dissecteddevelopment in African clawed frogs (Xenopus laevis). Larvae were testes of the three males. The embryos were allowed to hatch.exposed to atrazine (0.01–200 ppb) by immersion throughout After 4 days, the larvae were all mixed and netted into tanks 5larval development, and we examined gonadal histology and at a time repeatedly, until all tanks contained 30 larvae. Larvaelaryngeal size at metamorphosis. Atrazine (>0.1 ppb) induced were reared in 4 liters of aerated 10% Holtfreter’s solution (15)hermaphroditism and demasculinized the larynges of exposed and fed a solution of ground Purina rabbit chow daily. Foodmales (>1.0 ppb). In addition, we examined plasma testosterone levels were adjusted as the animals grew to maximize growth.levels in sexually mature males. Male X. laevis suffered a 10-folddecrease in testosterone levels when exposed to 25 ppb atrazine. Dosing. In Exp. 1, we exposed larvae to atrazine at nominalWe hypothesize that atrazine induces aromatase and promotes the concentrations of 0.01, 0.1, 1.0, 10.0, and 25 parts per billionconversion of testosterone to estrogen. This disruption in steroi- (ppb), whereas the second experiment used 0.1, 0.4, 0.8, 1.0, 25,dogenesis likely explains the demasculinization of the male larynx and 200 ppb atrazine. Concentrations were confirmed by twoand the production of hermaphrodites. The effective levels re- independent laboratories (PTRL West, Richmond, CA, and theported in the current study are realistic exposures that suggest that Iowa Hygienic Laboratory, Univ. of Iowa, Iowa City, IO). Allother amphibian species exposed to atrazine in the wild could be stock solutions were made in ethanol (10 ml), mixed in 15-gallonat risk of impaired sexual development. This widespread com- containers, and dispensed into treatment tanks. Controls werepound and other environmental endocrine disruptors may be a treated with ethanol such that all tanks contained 0.004%factor in global amphibian declines. ethanol. Water was changed and treatments were renewed once every 72 h. Each treatment was replicated 3 times with 30I n the last 10 years, a great deal of attention has focused on the global presence of endocrine-disrupting contaminants in theenvironment (1, 2). Similarly, a great deal of attention has animals per replicate (total of 90 animals per treatment) in both experiments. All treatments were systematically rotated around the shelf every 3 days to ensure that no one treatment or no onefocused on global amphibian declines (3, 4). In the case of tank experienced position effects. Experiments were carried outamphibian declines, efforts focus on identifying causes (5), at 22°C with animals under a 12-h 12-h light dark cycle (lights
  36. 36. Popular presscan be misleading
  37. 37. ARTICLEAudible Television and Decreased Adult Words,Infant Vocalizations, and Conversational TurnsA Population-Based StudyDimitri A. Christakis, MD, MPH; Jill Gilkerson, PhD; Jeffrey A. Richards, MA; Frederick J. Zimmerman, PhD;Michelle M. Garrison, PhD; Dongxin Xu, PhD; Sharmistha Gray, PhD; Umit Yapanel, PhDObjective: To test the hypothesis that audible televi- Outcome Measures: Adult word counts, child vocal-sion is associated with decreased parent and child izations, and child conversational turns.interactions. Results: Each hour of audible television was associatedDesign: Prospective, population-based observational with significant reductions in age-adjusted z scores for childstudy. vocalizations (linear regression coefficient, −0.26; 95% con- fidence interval [CI], −0.29 to −0.22), vocalization dura-Setting: Community. tion (linear regression coefficient, −0.24; 95% CI, −0.27 to −0.20), and conversational turns (linear regression co-Participants: Three hundred twenty-nine 2- to 48- efficient, −0.22; 95% CI, −0.25 to −0.19). There were alsomonth-old children. significant reductions in adult female (linear regression coefficient, −636; 95% CI, −812 to −460) and adult maleMain Exposures: Audible television. Children wore (linear regression coefficient, −134; 95% CI, −263 to −5) word count.a digital recorder on random days for up to 24months. A software program incorporating automatic Conclusions: Audible television is associated with de-speech-identification technology processed the creased exposure to discernible human adult speech andrecorded file to analyze the sounds the children were decreased child vocalizations. These results may ex-exposed to and the sounds they made. Conditional lin- plain the association between infant television exposure
  38. 38. FindingPrimary-SourceInformation
  39. 39. TitleAbstractIntroductionMethodsResultsDiscussionConclusion
  40. 40. TitleAbstractIntroductionMethodsResultsDiscussionConclusion
  41. 41. Laboratory for Integrative Studies in Amphibian Biology, Group in Endocrinology, Museum of Vertebrate ZooloUniversity of California, Berkeley, CA 94720-3140Communicated by David B. Wake, University of California, Berkeley, CA, March 1, 2002 (received for review DeceAtrazine is the most commonly used herbicide in the U.S. and human choriogonadotropinprobably the world. It can be present at several parts per million in harvesting gametes. Eggsagricultural runoff and can reach 40 parts per billion (ppb) in female and fertilized inprecipitation. We examined the effects of atrazine on sexual Ringer’s solution by using tdevelopment in African clawed frogs (Xenopus laevis). Larvae were testes of the three males.exposed to atrazine (0.01–200 ppb) by immersion throughout After 4 days, the larvae wlarval development, and we examined gonadal histology and at a time repeatedly, untillaryngeal size at metamorphosis. Atrazine (>0.1 ppb) induced were reared in 4 liters of ahermaphroditism and demasculinized the larynges of exposed and fed a solution of gromales (>1.0 ppb). In addition, we examined plasma testosterone levels were adjusted as thelevels in sexually mature males. Male X. laevis suffered a 10-folddecrease in testosterone levels when exposed to 25 ppb atrazine. Dosing. In Exp. 1, we expWe hypothesize that atrazine induces aromatase and promotes the concentrations of 0.01, 0.conversion of testosterone to estrogen. This disruption in steroi- (ppb), whereas the seconddogenesis likely explains the demasculinization of the male larynx and 200 ppb atrazine. Coand the production of hermaphrodites. The effective levels re- independent laboratories (ported in the current study are realistic exposures that suggest that Iowa Hygienic Laboratoryother amphibian species exposed to atrazine in the wild could be stock solutions were madeat risk of impaired sexual development. This widespread com- containers, and dispensedpound and other environmental endocrine disruptors may be a treated with ethanol sucfactor in global amphibian declines. ethanol. Water was change every 72 h. Each treatmI n the last 10 years, a great deal of attention has focused on the global presence of endocrine-disrupting contaminants in the animals per replicate (tota experiments. All treatmen
  42. 42. Find a scientific articleand read the abstract.
  43. 43. Scientific findings should beindependently verifiable
  44. 44. Scientific findings should beindependently reproducible
  45. 45. AtrazineLovers.comAtrazine.com
  46. 46. Theory
  47. 47. “...a unifyingexplanationfor a broad rangeof phenomena.’’
  48. 48. “A collection ofrelated hypothesesthat have beentested many timesand not rejected...’’
  49. 49. “There is no absolutetruth in science, however,only varying degreesof uncertainty.’’
  50. 50. TheScienceof Life
  51. 51. 1.1 - 1.4, 1.9

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