9. Enviro Sex Determ 2010

9. Enviro Sex Determ 2010 - Environmental Sex Determination...

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Unformatted text preview: Environmental Sex Determination Temperature Sex Determination • Common in many vertebrate species – Some fish – Some anurans and salamanders – Many turtles • cool females/warm males • generally cool males/warm females • Exception snapping turtle • female warm and cool/ male at moderate temperature • cool males/ warm females TSD 2 • Some lizards • All crocodilians – cool females/warm males – cool female/warm male – Also • Some birds? Not observed to date • Not observed in mammals • cool and hot females • males at moderate temperatures TSD Reptiles % Male Mechanisms • Hypothesis – Temperature alters estrogen production by the gonad, which influences differentiation – Temperature-dependent aromatase actvity in European Pond turtle (Emys obicularis) • Effect only on embryo early in differentiation Sex Differentiation in Fish XX / XY / Temperature (WY,WX, XX) / (YY, XY) Social cues Sex Differentiation in Frogs Sex Differentiation in Alligators TSD and Genes • Alligators have no SRY gene • Gonadal differentiation – – – – – – – – – DAX-1 SF-1 WT-1 SOX9 AMH DMRT-1 P450arom ERα β Heat Shock Female Gonads (♀) Dax1 WT1 SF1 Western & Sinclair JEZ 290 (2001) Male Gonads (♂) WT1 Sox9 AMH Western & Sinclair JEZ 290 (2001) American Alligator Embryos @ 33°C Western & Sinclair JEZ 290 (2001) Testosterone P450aromatase Estradiol-17β Quantitative Gene Expression in GAMs P450aromatase Male Gonads (♂) Female Gonads (♀) Katsu et al., unpubl. data Sex Reversal - % Sex Reversal - % Female Sex 100 100 80 80 60 60 40 40 20 20 0 0 t-Nona t-Nona 100ppt 100ppt 1ppb 1ppb 100ppb 100ppb 10ppm 10ppm 32.5°C :: Stage 19 :: N = 7-10 eggs32.5°C :: Stage 19 :: N = 7-10 egg // treatment 32.5°C Stage 19 N = 7-10 eggs32.5°C Stage 19 N = 7-10 eg treatment 100 100 1ppt 1ppt 80 80 60 60 40 40 20 20 Control Control uillette et al., unpubl. data uillette et al., unpubl. data 0 0 DDD DDD+tN Dicofolt-Nona DDD DDD+tN Dicof Estradiol DDD DDD+tN Dicofolt-Nona DDD DDD+tN Dico Estradiol Guillette et al., unpubl. data Guillette et al., unpubl. data Gene Expression in Neonatal Gonads Incubated at Male or Female Temperatures, or at Male Temperature Exposed to Estrogen ERα 1.4 1.2 1 0.8 0.6 0.4 0.2 0 SF1 500 450 400 350 300 250 200 150 100 50 0 Aromatase M male M-E2 male E2 female F M M-E2 DMRT1 F M male M-E2 male E2 female F AMH 1.4 1.2 1 0.8 0.6 0.4 0.2 0 SOX9 M M-E2 F M M-E2 F M male M-E2 male E2 female F Katsu et al. unpubl. data ...
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This note was uploaded on 05/19/2011 for the course ZOO 4926 taught by Professor Staff during the Summer '08 term at University of Florida.

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