Zebrafish Per3 gene circadian oscillation reflects tissue dependent temperature compensation

HERNANDEZ DE BORSETTI, N; KANEKO, M; CAHILL G.M.

Cordoba, Los Cocos

Simposio; 8th Latin-American Symposium of Chronobiology; 2005

Zebrafish Per3 gene circadian oscillation reflects tissue dependent temperature compensation     Hernandez de Borsetti, N.; kaneko, M.; and Cahill G.M.   Dept. of Biology and Biochemistry, University of Houston, Houston, Tx 77204     Temperature compensation is one of the common of circadian systems. By definition, the free-running circadian period lengths in an organism are very similar when measured at different ambient temperatures.  A transgenic Zebrafish was created in our laboratory which expresses the firefly luciferase gene under the control of the promoter of the zebrafish circadian gene period3 (per3). Here we report temperature compensation for zPer3 rhythms in different organs of Zebrafish. Tissues and organs from this transgenic fish were dissected and cultured in 67% Leibovitz¡¯s L-15 medium (L-15; Invitrogen) while monitoring for bioluminescence rhythms at 24¨¬C and 32¨¬C. Results: These rhythms varied in the temperature compensation depending on which tissues were studied. The bioluminescence rhythms in the retina, pineal gland, gill, heart and gall bladder showed slight but significant overcompensation with Q10 values ranging from 0.89 in the retina to 0.96 in the gill. These Q10 values are within the range of circadian rhythms in various organisms. The two-way analysis of variance (ANOVA), performed on these five tissues and temperature as variables, showed significant effects of tissue, temperature, and tissue x temperature interaction on period lengths (p<0.0001, p<0.0001, p<0.0001, and p=0.003, respectively; ¥á=0.007). In contrast, the spleen showed perfect temperature compensation with insignificant period differences between the two temperatures (p=0.07, t-test). Conclusion: This is the first evidence of tissue-dependent differences of Q10 values for circadian rhythms within species.