181 Multi-tissue transcriptomic analysis of the effects of supplementation of L- or D-methionine in acute heat stress-exposed broiler chickens.

摘要

The objective of this study was to compare the effects of two isoforms of methionine (Met) supplementation, L-Met or D-Met, on transcriptome expression in broiler chickens under acute heat stress. A total of 240 one-day-old chicks were randomly assigned to one of four treatments in a 2 × 2 factorial arrangement: thermo-neutral vs. acute heat-stress and L-Met vs. D-Met supplementation. On day 14, the heat-stressed group was exposed to 32°C for 6 h, while the others remained at 25ºC. Six chicks per treatment were randomly selected and harvested to isolate total RNA from the blood, ileum, and liver tissues. Two RNA samples from each tissue of the same treatment group were randomly selected and pooled with equal amount. A total of 1.87 billion of raw reads were obtained from 36 samples (four treatments × three tissues × three composited replicates) using the Illumina HiSeq 4000 platform. The reads, mapped to the reference genome build (Gallus_gallus-5.0), were used to identify differentially expressed genes (DEG, false-discovery rate < 0.05) using DESeq2. Functional enrichment of DEG was tested using DAVID. A total of 38, 71, and 16 genes were differentially expressed in response to the interaction between heat stress and Met isoforms in the blood, ileum, and liver, respectively. These DEGs were functionally enriched for regulation of cholesterol homeostasis, gluconeogenesis, and bile acid synthesis. Unlike the L-Met group, , , and , related to immune response, neuroprotection, cell proliferation, and dedifferentiation, were all increased by heat stress in the D-Met group. The expression of , , , related to abnormally increased blood glucose by heat stress, were also changed in the D-Met. Compared to D-Met, L-Met supplementation appeared to reduce abnormal cellular and physiological responses by heat stress in broilers.