RNA Sequencing Analysis of the Circadian Rhythm Gene Expression in the Pineal Gland of Chickens
The expression characteristics and biological significance of White Leghorn chicken's pineal gland genes in the regulation of circadian rhythms were studied.Samples were collected on the 10th day every 4 hours during a 24-hour dark period to obtain time-series data of pineal gland gene expression in White Leghorn chickens raised under a 12-hour light/12-hour dark cycle.The periodically-expressed genes were identified with R language,and the gene clusters with similar expression patterns were identified with weighted gene co-expression network analysis(WGCNA).Subsequent trait association and functional enrichment analyses were performed,and the key hub genes related to circadian rhythm were screened with Cytoscape.Results showed that rain algorithm identified periodically-expressed genes,and WGCNA revealed distinct expression patterns of several circadian genes(AANAT,PER2,ROR1,ARNTL,CLOCK,PER3,CRY2,CRY1)in pineal cells that clustered into modules of different colors with significant different expression patterns.Association heat maps and enrichment analyses indicated that different biological processes were sequentially activated at various times of the day,highlighting their roles in circadian rhythm regulation.The hub genes identified with CytoHubba plugin in Cytoscape further supported these findings.The results show that pineal cells are highly complicated and dynamic in responding to and regulating circadian rhythm.