Undergraduate Thesis Defense Slides

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Heather Jordan's undergraduate thesis defence from Lake Superior State University (spring 2001).

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Undergraduate Thesis Defense Slides

  1. 1. Density-Dependent Sexual Differentiation in Single-Nuclear Mutants of Ceratopteris richardii Heather E. Jordan Biology Department College of Health and Natural Sciences Lake Superior State University Sault Ste. Marie, MI 49783
  2. 2. 06/03/09 Introduction
  3. 3. 06/03/09 What is Ceratopteris richardii ? <ul><li>- A semi-aquatic, homosporous fern </li></ul><ul><li>- Commercially available in a variety of mutant stocks </li></ul><ul><li>- Sex ratios of the gametophytes are subject to population pressures </li></ul>
  4. 4. 06/03/09 Why study C. richardii? <ul><li>Wide variety of mutant strains </li></ul><ul><li>Large sample sizes require little space </li></ul><ul><li>Grow quickly </li></ul><ul><li>Swimming sperm makes it interesting to “anti-botanists” </li></ul>
  5. 5. 06/03/09 Notes of Interest: <ul><li>As the growth density increases, more A Ce is secreted into the surrounding medium. </li></ul><ul><li>A ce causes developing gametophytes to become male </li></ul><ul><li>Therefore,  growth density leads to  in the percentage of males in a population. </li></ul>
  6. 6. 06/03/09 Factors Influencing the Effects of the Pheromone on the Sex Ratio: <ul><li>Growth rate of gametophytes </li></ul><ul><li>Production and diffusion of the antheridiogen </li></ul><ul><li>Influence of growth promoters and inhibitors </li></ul><ul><li>Gametophytic growth density </li></ul>
  7. 7. 06/03/09 Project Objective <ul><li>Test the effects of various types of single gene nuclear mutations on density-dependent sexual differentiation in C. richardii . </li></ul>
  8. 8. 06/03/09 Hypothesis <ul><li>Populations of mutant strains not bred to exhibit an altered response to the antheridiogen A Ce will yield sex ratios similar to those found in a wild type population. </li></ul>
  9. 9. Summary of Strains Investigated GenotypeCode Generic Name RNWT 1 Wild Type abr48 Abscisic Acid Tolerant cp Polka Dot det30 Non-Etiolated fdr1 FUDR Tolerant her1 Maleless him1 Highly Male rum1 Rumpled slo1 Slo-Mo Sperm stl2 Salt Tolerant zzz1 Sleepy Sperm
  10. 10. 06/03/09 Methods & Materials
  11. 11. 06/03/09 Sowing The Spores: <ul><li>To synchronize germination, the spores were soaked in 4 mL of distilled water for a week in complete darkness. </li></ul><ul><li>Since 1 drop contains about 100 spores, different growth densities can be obtained by adjusting the number of drops used to inoculate each plate. </li></ul>
  12. 12. 06/03/09 Experimental setup of the culture dome for each genotype:
  13. 13. Temperature: 28 o C pH = 6 Photoperiod : 24 hour
  14. 14. 06/03/09 How do you know which ones are male? <ul><li>Male Cordate </li></ul>
  15. 15. 06/03/09 Counting Methods <ul><li>1. A quadrant was selected at random. </li></ul><ul><li>2. All gametophytes were counted and sexed in that quadrant. </li></ul><ul><li>3. Obtained numbers were multiplied by 4 for a final estimate. </li></ul>
  16. 16. 06/03/09 To make the counting a little easier… <ul><li>Projection onto a computer monitor using the Intel  QX3  Microscope. </li></ul>
  17. 17. 06/03/09
  18. 18. 06/03/09 Statistical Analysis <ul><li>Single Factor Model I ANOVA’s between the 11 strains were calculated for: </li></ul><ul><li>The mean number of spores germinated </li></ul><ul><li>The mean percentage of males present . </li></ul>
  19. 19. 06/03/09 Results
  20. 20. 06/03/09 Could there be a trend? 14.5 89.9 cp 17.6 135.9 zzz1 13.5 136.3 det30 98.8 140.8 him1 13.9 157.1 slo1 0.00 211.9 her1 15.4 249.3 stl2 36.5 249.3 abr48 28.9 255.2 fdr1 19.8 281. 2 rum1 34.6 360.9 RNWT1 Mean % Male Mean # of Gametophytes Strain
  21. 21. 06/03/09 F Values 22.12 26.90 4.01 RNWT1 vs. cp 13.26 15.77 4.01 RNWT1 vs. zzz1 21.10 16.66 4.01 RNWT1 vs. det30 295.66 16.38 4.01 RNWT1 vs. him1 24.69 13.54 4.01 RNWT1 vs. slo1 87.16 6.06 4.01 RNWT1 vs. her1 18.30 2.92 4.01 RNWT1 vs. stl2 0.16 3.18 4.01 RNWT1 vs. abr48 1.51 2.80 4.01 RNWT1 vs. fdr1 11.39 1.66 4.01 RNWT1 vs. rum1 Mean % Male Mean # Gametophytes Fcrit
  22. 22. 06/03/09 The percentage of males increases with a rise in the population density across each strain.
  23. 23. 06/03/09 The overall composition of each genotype sample:
  24. 24. 06/03/09 Discussion
  25. 25. 06/03/09 In Summary… <ul><li>Differences observed in the percentage of males found within each strain appears to be dependent on how well a particular strain grows under standard conditons. </li></ul><ul><li>There were no significant differences between the growth rates of chemically tolerant mutants and the wild type. </li></ul><ul><li>Significant differences in growth rates were found in mutants carrying genes for structural mutations . </li></ul><ul><li>Only 2 strains showed no significant differences in growth rate but exhibited significant differences in the percentage of males present in each sample (stl2 & rum1). </li></ul>
  26. 26. 06/03/09 Chemical Tolerance (abr48, fdr1, and stl2) <ul><li>Previous studies show significant differences in growth rates. </li></ul><ul><li>Typically, mutants grown in the absence of the chemical they were bred to resist do not grow as well as the wild type. </li></ul>
  27. 27. 06/03/09 Structural Mutations ( det30, cp, slo1, and zzz1) <ul><li>These strains had the lowest germination rate . </li></ul><ul><li>The nature of the mutation may result in functional impairments . </li></ul><ul><li>Possibly a consequence of the mutagenic process itself. </li></ul><ul><ul><li>Chemical treatment and/or radiation of plant tissues has been shown to induce chromosome stickiness ). </li></ul></ul>
  28. 28. 06/03/09 Strains with altered differentiation patterns and normal growth rates <ul><li>This experiment did not test for: </li></ul><ul><ul><li>antheridiogen production by the gametophytes </li></ul></ul><ul><ul><li>The influence of mutations on growth promoters and inhibitors in the strains studied. </li></ul></ul><ul><ul><li>Perhaps testing the stl2 and rum1 strains for these things may be helpful in finding out if these two strains possess an altered sensitivity to the antheridiogen. </li></ul></ul> Hint, hint– Junior Seminar Students!!! 

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