# Multi-Organ Transcriptomic Analysis of Greater Amberjack (Seriola dumerili) with Different Growth Rates

## TL;DR

This study explores how genes and biological pathways in the greater amberjack's organs relate to differences in growth rates, offering insights for breeding programs.

## Contribution

The study identifies specific genes and pathways in three organs linked to growth, metabolism, and immunity in fast- and slow-growing greater amberjack.

## Key findings

- Fast-growing amberjack showed up-regulated genes related to growth and lipid metabolism.
- Slow-growing amberjack exhibited up-regulated genes involved in glycolysis and immune responses.
- Differential gene expression suggests distinct energy allocation strategies between growth groups.

## Abstract

The greater amberjack (Seriola dumerili) is a highly valued fish known for its tasty meat, nutritional richness, and rapid growth rate. However, the molecular mechanisms underlying its growth traits remain poorly understood. In this study, transcriptome sequencing was performed on the hypothalamus, pituitary, and liver tissues of 12-month-old greater amberjack with different growth rates. A number of genes and biological pathways that related to growth, cell proliferation, lipid and glucose metabolism, and immune responses were screened. These findings contributes to a deeper understanding of the growth control mechanism in greater amberjack and offers a scientific basis for efficient breeding and species improvement.

In order to explore the main regulatory genes and related pathways of growth traits, transcriptome sequencing was performed on the hypothalamus, pituitary, and liver tissues of 12-month-old greater amberjack (Seriola dumerili) with different growth rates. In total, 504 (118 up- and 386 down-regulated), 556 (283 up- and 273 down-regulated), and 699 (224 up- and 475 down-regulated) differentially expressed genes (DEGs) were identified in the hypothalamus, pituitary, and liver tissues, respectively. GO and KEGG pathway analyses revealed significant differences in the expression of several genes involved in growth, metabolism, and immune-related pathways. The mRNA expression levels of genes related to growth (ghrh, ghra, igf1), cell proliferation (fgf19, fgfr4, mapk8b, map2k4b, and map4k3), and lipid metabolism (acsl5, dgat2, lipeb, cyp7a1, and fabp10a) were up-regulated in the fast-growing (FG) group, while the cartl and sst1.1 were down-regulated. Conversely, genes associated with glycolysis (fbp1a, pklr, pgm2), citrate cycle (aclya, idh1), and immune-related pathways (irf1b, cxcl10, tnfb, lysg, ifi44, mapk11, and mapk12b) were up-regulated in the slow-growing (SG) group. These findings indicate that the FG exhibited greater lipid metabolism capacity and cell proliferation ability, while the SG expended additional energy to cope with environmental stress, with hindered growth during immune response. This study enhances our understanding of the genetic mechanisms underlying differences in growth rates and provides essential gene resources for future growth-related molecular breeding programs in greater amberjack.