Knowledge Bank

The developing avian embryo is reliant on external sources of heat. Incubation temperatures above or below optimal alter development and metabolic function, and may compromise emergence and post-hatch adaptation. Studies in chick embryos indicate that high incubation temperature increases glycolysis and reduces hepatic glycogen needed during hatching. As a key glycolytic enzyme, phosphofructokinase-1 (PFK-1) is a likely target for the temperature-induced effects on pathways of glucose metabolism. However, there is limited data characterizing PFK-1 in avians exposed to high incubation temperatures. This study used real time PCR to compare PFK-1 mRNA transcript amounts within the breast muscle and liver tissue of the precocial japanese quail (Coturnix japonica) and the semi-altricial domestic pigeon (Columbia livia). Tissue samples were collected previously from birds exposed to increased incubation temperatures (40.8˚ for 3 hours during embryonic d 10 and 11 for quail, and d 13 and 14 for pigeon, equivalent to Hamburg and Hamilton stages 39 and 40) or a control temperature (37.6˚ C throughout incubation). Total RNA was isolated, reverse transcribed, and cDNA was pooled by species and heat treatment for analysis. High incubation temperatures resulted in a down regulation in PFK-1 transcript amounts in both liver and breast muscle in pigeons. Transcript amounts were 50 and 2.78 fold greater for liver and breast muscle, respectively, for birds incubated under control temperatures compared to high heat. Similarly, PFK-1 transcript amounts in quail liver of birds exposed to high incubation temperatures was 80% the value of the control, but breast muscle PFK-1 transcript amounts increased to 165%. Findings suggest unique effects of incubation temperature for precocial compared to altricial species.