Transcriptome, enzyme activity and histopathology analysis reveal the effects of high level of dietary carbohydrate on glycometabolism in juvenile golden pompano,Trachinotus ovatus

Abstract

Golden pompano (Trachinotus ovatus) is an important aquaculture species in Chinaand broadly cultivated in Asia-Pacific region. Our previous study found that T. ovatus had a better tolerance to the high level of carbohydrate in diet (360 g/kg) compared to Micropterus salmoides. Present study investigated the tolerance mechanism of T. ovatus to high level of dietary carbohydrate (PH-360 g/kg of corn starch) on transcriptome level using Illumina sequencing compared to optimum level of dietary carbohydrate (PM-240 g/kg corn starch). A total of 208,952,492 reads were obtained and assembled into 62,377 unigenes with an average length of 822 bp and a range of 200-16,206 bp. Transcriptome annotation revealed that 27,636 unigenes with a cut-off e-value of 10 −5 were functionally annotated. Specifically, 7,903 unigenes were clustered into 24 functional categories by searching against the COG database, 12,161 unigenes to 84 GO terms, 26,835 unigenes to Nr database and 23,681 unigenes to SWISS-PROT database. In addition, 13,739 unigenes were grouped into 240 KEGG pathways. There are 3,461 differentially expressed genes in PH compared to PM, in which 3,059 unigenes were significantly upregulated and 402 unigenes were significantly downregulated. Twelve key genes related to carbohydrate metabolism were further validated by quantitative real-time RT-PCR, and the results were consistent with those of transcriptome profile. Under high level of dietary carbohydrate (PH-360 g/kg), the results indicate that T. ovatus can adapt to the high level of carbohydrate in diet by enhancing glycolysis with hepatic HK enzyme activity was significantly increased (p > 0.05), reducing gluconeogenesis with the decreased trend of PEPCK enzyme activity and maintaining the homeostasis of carbohydrate metabolism-related hormones and hormone receptor gene expressions. Histopathological examination has shown that liver cavity area was significantly increased (p > 0.05), but no visible nutritional diseases are found in fish. This study provides a valuable understanding of the molecular responses of T. ovatus fed by the high level of dietary carbohydrate (PH-360 g/kg).

Dietary carbohydrate‐to‐lipid ratios modulate juvenile hybrid grouper (♀ Epinephelus fuscoguttatus × ♂ E. lanceolatus ): Effects on growth, serum biochemistry, intestinal digestion and hepatic metabolism of glucose and lipid

“…A previous study on juvenile largemouth bass (Micropterus salmoides) conducted by Zhang et al (2019) found that marine carnivorous fish have ability to utilize dietary carbohydrate by analysing transcriptome and enzyme activity. Liu et al (2019) obtained similar results in an experiment of juvenile golden pompano (Trachinotus ovatus) by feeding high dietary carbohydrate.…”

Effects of fishmeal replacement with cottonseed protein concentrate on growth, digestive proteinase, intestinal morphology and microflora in pearl gentian grouper (♀ Epinephelus fuscoguttatus × ♂ Epinephelus lanceolatu )

“…As a result, R36 had a higher dietary carbohydrate content than R24. Studies suggested that carnivorous fish had low utilization of dietary carbohydrate (Liu et al, 2019; Yang et al, 2018; Zhang et al, 2019), which may be the reason for the lower growth of the R36 group. The study by Shimeno et al (1996) found that a high level of dietary carbohydrate adversely affected fish growth, feed conversion and protein retention.…”

The Single-Molecule Long-Read Sequencing of Intestine After Soy Meal-Induced Enteritis in Juvenile Pearl Gentian Grouper, Epinephelus fuscoguttatus♀ × Epinephelus lanceolatus♂

“…In our unpublished research on the pearl gentian grouper transcriptomes of the intestine and liver tissues, the transcript annotation rates were 32.64 and 36.58%, respectively. Also, in our published articles on M. salmoides and Trachinotus ovatus, in which the transcriptomes were sequenced by the Illumina 2000 platform, the annotation rates of the transcripts were 52.98% (26,886/50,743) (Zhang et al, 2019) and 43.30% (27,366/62,377) (Liu et al, 2019), respectively. Although the raw data obtained from third-generation sequencing had relatively more error, it can be corrected through the data obtained from next-generation sequencing (Hackl et al, 2014).…”