Effect of fasting and subsequent refeeding on the transcriptional profiles of brain in juvenile Spinibarbus hollandi

Abstract

Starvation is a common stress in fish. The underlying molecular mechanisms associated with growth depression caused by feeding restriction and compensatory growth are not well understood. We investigated the effect of fasting and refeeding on the transcriptome profiles of brain in juvenile S. hollandi using RNA-seq. A total of 4.73 × 108 raw reads were obtained from nine brain samples. De novo transcriptome assembly identified 387,085 unigenes with 2.1×109 nucleotides. A total of 936 annotated unigenes showed significantly differential expression among the control, fasting, and fasting-refeeding groups. The down-regulated differentially expressed genes (DEGs) during fasting were mainly associated with cell cycle, DNA replication, and mitosis. The up-regulated DEGs were mainly related to glucose and lipid metabolism, material transportation, and transcription factors. Most decreased DEGs during fasting were restored to normal levels after refeeding. Comparing with the control group, genes associated with protein synthesis, stimulus response, and carbohydrate metabolism were significantly over-expressed and pro-opio melanocortin (POMC) was down-regulated during the refeeding period. In conclusion, fish mobilized stored energetic materials and reduced energy consumption to prolong survival during fasting. After refeeding, the down-regulation of DEGs, e.g., POMC may be associated with compensatory growth. Up-regulation of DEGs related to ribosomal protein, stimulus response, and carbohydrate metabolism may contribute to eliminate negative effect of starvation on brain. This study provided the first transcriptome data related with impact of short-time starvation and refeeding in S. hollandi brains.

Fig 1. Growth curves of Spinibarbus hollandi under continuous feeding and fasting-refeeding.

Asterisk indicated significant difference between two groups (p < 0.05); blue line represented the growth curve for the continuous feeding groups; red line indicated the growth curve for the fasting-refeeding groups.

Fig 2. Classification of down-regulated DEGs during fasting according to KEGG database.

Fig 3. Classification of up-regulated DEGs after 7-day refeeding according to KEGG database.

Fig 4. Analysis of the expression profiles of key genes using qRT-PCR.

Asterisk indicates significant difference (p < 0.05), a~f represent the expression profiles of CDC6, CDC20C, MCM2, DHCR7, FABP7, and HSP70, respectively.

Fig 5. Correlation between results of RNA-seq and qRT-PCR.

a and b represent correlations between control and fasting groups, and between control and refeeding groups, respectively. X-axis numbers represent the log₂ (fold change) values from RNA-seq results. Y-axis numbers represent the log₂ (fold change) values from qRT-PCR results.