Effects of uvb radiation on the skin lipids of garter snakes
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Effects of UVB radiation on the skin lipids of garter snakes. Anna Vigeland Dr. M. Rockwell Parker Dr. Robert T. Mason. Study Species. Red-sided Garter Snake ( Thamnophis sirtalis parietalis ) Model organism Hibernate 8 months in large hibernacula Emerge by the thousands in late spring

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Effects of uvb radiation on the skin lipids of garter snakes l.jpg

Effects of UVB radiation on the skin lipids of garter snakes

Anna Vigeland

Dr. M. Rockwell Parker

Dr. Robert T. Mason


Study species l.jpg
Study Species

Red-sided Garter Snake (Thamnophis sirtalis parietalis)

  • Model organism

  • Hibernate 8 months in large hibernacula

  • Emerge by the thousands in late spring

  • Breeding follows for a few weeks

  • Courtship behavior mediated by pheromones produced in the skin


Garter snake environment l.jpg
Garter Snake Environment

  • Most northerly living reptile

  • Study snakes caught at dens in Manitoba

  • Northern regions strongly subject to

    environmental changes

  • UVB radiation


Skin lipid profile l.jpg
Skin Lipid Profile

  • 18 long-chain saturated and monounsaturated methyl ketones in pheromone

  • High ratios of unsaturated and high molecular weight methyl ketones are associated with large, healthy females

  • Males differentiated in part by the presence of squalene

more attractive

less attractive


Skin lipid profile5 l.jpg
Skin Lipid Profile

Gas chromatograph of a typical female pheromone sample

504

Saturated

Unsaturated

478

532

450

518

476

506

490

448

422

464

492

436

394

420

462

408

434


Objective l.jpg
Objective

Methyl ketone ratios change during the summer

in the field but not in the lab

Why?


Hypothesis l.jpg
Hypothesis

Ultraviolet radiation causes qualitative changes in the skin lipid profiles of red-sided garter snakes


Question 1 l.jpg
Question 1

Does ultraviolet-B radiation have an effect on the female sexual attractiveness pheromone?



Uvb radiation on female pheromone samples l.jpg
UVB radiation on female pheromone samples

Full-spectrum light only

Full-spectrum and UVB light


Slide11 l.jpg

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Question 2 l.jpg
Question 2

Does ultraviolet-B radiation have the same effect on the female sexual attractiveness pheromone when in mixture with other skin lipids?



Pheromone irradiated within neat solution l.jpg
Pheromone irradiated within neat solution

Full spectrum light only

Full spectrum and UVB light



Live animal exposure overview l.jpg
Live-animal exposure: overview

  • Two groups of snakes exposed to either full spectrum or full spectrum +UVB light

  • Behavioral and physical changes examined after prolonged UV exposure

  • Skin lipid analysis after exposure period


Question 3 l.jpg
Question 3

Does exposure to ultraviolet-B radiation have an effect on the behavior of red-sided garter snakes?


Methods20 l.jpg
Methods

Short-term: detection and/or avoidance of UVB light

  • Cardboard tube test: % snakes seeking refuge in tubes

  • Mylar filter test: % snakes situated under Mylar vs. acetate

    Long-term: snake activity levels

  • Observation and categorization of behaviors:

    % snakes active, alert, or resting


Uvb radiation does not affect snake behavior l.jpg
UVB radiation does not affect snake behavior

  • No significant differences in number of snakes seeking refuge in cardboard tubes

  • Equal numbers of snakes situated under Mylar filters as under acetate filters

  • No significant differences in the activity levels between treatment groups or after the 15-day exposure period


Question 4 l.jpg
Question 4

What effects does daily exposure to ultraviolet-B radiation have on the neutral skin lipids of red-sided garter snakes?


Methods23 l.jpg
Methods

  • Skin lipid extraction by soaking in hexane

  • Purification of female attractiveness pheromone and squalene by alumina column chromatography

  • Analysis of pheromone concentrations by gas chromatography



Environmental implications l.jpg
Environmental Implications

  • UVB radiation has an effect on the female attractiveness pheromone and its US:S ratio

  • UVB radiation has been increasing, especially in polar latitudes, due to ozone depletion

  • Increases in UVB could affect red-sided garter snake reproductive behavior


Further research l.jpg
Further Research

  • Gas chromatography analysis of squalene concentrations

  • Thin layer chromatography to test for major differences in other neutral skin lipids


Acknowledgements l.jpg
Acknowledgements

Funding provided by:

  • Howard Hughes Medical Institute

    Special thanks to:

  • Dr. Robert T. Mason

  • Dr. M. Rockwell Parker

  • Mason Lab: Emily Uhrig, Mattie Squire, Chris Friesen, Ben Burke

  • The Blaustein Lab



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