Artificial hybrid breeding can optimize parental traits to cultivate excellent hybrids with enhanced economic value. In this study, we investigated the growth performance and transcriptomes of Gymnocypris przewalskii (♀) and Gymnocypris eckloni (♂) and their F1 hybrid fishes. Hatched individuals of G. przewalskii (GP) and G. eckloni (GE) of the same size and their F1 hybrids (GH) were separately cultured for eight months in three cement tanks (n = 3). The growth indexes were measured, which showed that the growth rate of the groups was GE > GH > GP, while the survival rate was GH > GE > GP. The RNA-Seq data analysis of the muscles from the three Gymnocypris fish strains revealed that gene transcription has a significant impact on F1 hybrid fish and its parents. The differentially expressed genes (DEGs) in GH show less differences with GP, but more with GE. qRT-PCR was used to confirm the expression profiles of the chosen DEGs, and the results showed positive correlations with the RNA-seq data. KEGG enrichment results indicated that the DEGs were related to a variety of molecular functions, such as glycolysis/gluconeogenesis, arachidonic acid formation, citrate cycle, and the MAPK, PI3K-Akt, or mTOR signal pathways. Subsequent analysis indicated that there may be a significant correlation between the differential expression of IGF2 and a difference in the growth of GE and GP.

A 19-day experiment was conducted to investigate the optimal light intensity and photoperiod combination for larval swimming crabs Portunus trituberculatus in terms of survival, development, and apoptosis-related gene expression. Two photoperiods, i.e., 12 and 18 h photophases, and three light intensities, i.e., 126.08, 173.17, and 191.53 μmol m⁻² s⁻¹, were used in the study. The results showed that the cumulative survival rate (CSR) of larvae decreased with the increasing light intensity, and the adverse effect of high light intensity was only observed in long photophase groups. On the contrary, a long photophase and low light intensity elevated the CSR from zoea III to juvenile crabs. A long photophase also accelerated the development of zoea III larvae and upregulated the molting-related (ecr and rxr) and apoptosis-related (jnk, p53, and bcl-2) gene expressions. Taken together, the present study suggested that the light intensity and the photoperiod had a combined effect on P. trituberculatus larvae. The optimal light intensity and photoperiod for P. trituberculatus larvae were 126.08 μmol m⁻² s⁻¹ and an 18 h photophase, respectively.

Genetic composition plays a crucial role in the growth rate of species, and transcriptomics provides a potent tool for studying genetic aspects of growth. We explored the growth rates and transcriptomes of the Cyprinids G. przewalskii (GP) and G. eckloni (GE). A total of 500 individuals of G. przewalskii and G. eckloni, matched in size, were separately cultured for 9 months in six cement tanks (each group with three replicates). Growth indices were measured, revealing that the growth rate of GE was greater than that of GP (p < 0.05), while there was no significant difference in survival rates (p > 0.05). Simultaneously, we conducted RNA-Seq on the muscles of both GP and GE. The results indicated a significant difference of gene expression between GP and GE, identifying 5574 differentially expressed genes (DEGs). Quantitative real-time reverse transcription–polymerase chain reaction of 10 DEGs demonstrated consistency in expression profiles with the results from the RNA-Seq analysis. The DEGs were significantly enriched in glycolysis/gluconeogenesis (ko00010), arachidonic acid formation (ko00061), arginine biosynthesis (ko00220), and the MAPK (ko04013), PI3K-Akt (ko04151), mTOR (ko04150), and TGF-β (ko04350) signal pathways, as revealed by Gene Ontology (GO) enrichment and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. This study also identified some growth-related DEGs, such as IGF2, Noggin, Decorin and others. Notably, the low expression of IGF2 may be a factor contributing to the slower growth of GP than GE.

Hybrid breeding is an effective approach to generate better varieties and prevent variety degradation. The present study investigated the metabolic changes underlying growth superiority in the novel Gymnocypris hybrid (GH), Gymnocypris przewalskii ♀ (GP) × G. eckloni ♂ (GE). The ranking of survival rate was GH > GE > GP, whereas the ranking of growth rate was GE > GH > GP. A proteomic analysis of G. hybrid and its parents was conducted to elucidate the metabolic changes underlying growth superiority. Identified pathways were primarily associated with amino acid, carbohydrate, energy, lipid, and nucleotide metabolism. These metabolic pathways, which are closely associated with growth, are controlled through regulation of the expression of numerous proteins, including adenosylhomocysteinase, hydroxypyruvate reductase, glutamate-cysteine ligase, L-lactate dehydrogenase, creatine kinase, GDP-L-fucose synthase, pyruvate kinase, fructose-bisphosphate aldolase, carbonic anhydrase, phosphopyruvate hydratase, phosphoglycerate kinase, S-(hydroxymethyl) glutathione dehydrogenase, and AMP deaminase. Real-time PCR assays showed that the level of mRNA expression of differentially expressed genes was positively correlated with growth. Proteins that were differentially expressed in GH exhibited fewer differences from GP and more differences from GE. These data are the first to reveal the molecular mechanism whereby growth is regulated in G. hybrid and its parents at the protein level. The study thus provides important information for genetic breeding and improvement of G. hybrid for aquaculture production.