Purpose: Evidence has shown that hypoxic heart have greater heart mass fetal mass ratio. But it is still unclear if it is hyperplasia or cardiac hypertrophy that is happening. Furthermore the genes that might be involved in the process have not yet been identified. In the present study, the cardiac transcriptome was analyzed to identify differentially expressed genes related to hypoxia.

Methods: Eggs were incubated for 15 and 19 days in two different environments, normoxic and hypoxic. Normalized microarray results were analyzed to isolate differentially expressed probes using the affymetrix chip. Total RNA was also isolated from another set of fetuses incubated in the same conditions and used to perform a qPCR in order to confirm the microarray results.

Results: In the four groups (15N, 15 H, 19N, 19H), some probes were differentially expressed. From the eggs incubated up to 15 days, the microarray revealed 5 probes that were differentially expressed according to the criteria (p>0.01 and absolute fold change FC>2) in the two programs (PLIER & RMA) used to normalise to data. From the eggs incubated up to 19 days, 8 probes were differentially expressed in both programs. No further tests were performed on the 19 days fetuses since there was no statistical significance in that group after incubation. apo-A1, p22, similar to ENS-1 and b2 adrenergic receptor were further tested in qPCR. There were not confirmed. 

Discussion: Chicken hypoxic hearts have increased heart mass/fetal mass ratio. Some of the identified genes are linked to cell division and others have no known function. They all merit further study for potential involvement in cardiac remodelling.