RNA-Seq of Chicken Embryo Liver Reveals Transcriptional Pathways Influenced by Egg Formaldehyde Treatment.

BACKGROUND/OBJECTIVES: Hatchery fumigation is recognized as a crucial step to control microbial bloom in the environment, and formaldehyde is one of the most widely used disinfectants to ensure successful hatchability and healthy production. While many of the benefits are thought to be derived from disinfectant properties, it is possible that additional host gene and genetic pathway modulation could contribute to these outcomes. The current study aimed to capture the in ovo transcriptional response of liver tissue to formaldehyde treatment.

METHODS

Chick embryos were subjected to formaldehyde fumigation treatment for 25 min at 24-25 °C and 75% relative humidity, keeping a control group as untreated. On the 18th day of incubation at 37.8 °C and 58-63% humidity, eggs were broken, and liver tissue was obtained for RNA isolation, cDNA library preparation, and RNA sequencing.

RESULTS

Bioinformatics analysis revealed 908 significant differentially expressed genes (DEGs), among which 814 were known genes and 94 were novel genes. A total of 672 DEGs were upregulated, whereas 236 genes were downregulated in response to FA treatment. Of the 94 novel genes, 80 were upregulated. Key DEGs, associated QTLs, and transcription factors were involved in immuno-inflammatory responses, oxidative stress, epigenetic modification, and cellular adaptation-related activities. Further research should focus on biological validation of key DEGs to clarify their roles, pathways, and relationships to FA treatment.

CONCLUSIONS

Overall, these findings (1) provide critical molecular detail as a first step towards genetic selection to improve formaldehyde treatment response and effectiveness, and (2) provide DEG signatures for FA treatment as a reference against which to compare other interventions to achieve hatchability and production benefits.