Identification and Characterization of a Non-muscular Myostatin in the Nile Tilapia

Abstract

The growth and differentiation factor Myostatin (MSTN, also known as GDF8) negatively regulates skeletal muscle development and growth in vertebrates. Most fish genomes contain two or more mstn genes, which are expressed in muscle and other tissues. Yet, in the genome of Nile tilapia (Oreochromis niloticus), which is one of the world's most important aquaculture fish species, only one mstn gene has previously been identified. Here, we identify a second mstn gene in Nile tilapia. We show that it clusters phylogenetically with other piscine mstn2 genes and that it shares chromosomal synteny with the human and zebrafish orthologs. We further show that mstn2 is not expressed in red or white muscles of Nile tilapia, but rather that its main site of expression is the brain. To determine which physiological functions are correlated with mstn expression, adult Nile tilapia were exposed to various environmental conditions and their effect on mstn1 and mstn2 expression in the brain and muscles was measured using real-time PCR. We found that the centrally-and muscle-expressed mstn genes differ in their responsiveness to diverse challenges, suggesting differential gene-and tissue-specific regulation of their expression. Metabolic and stress marker analyses showed that the altered mstn expression is not regulated by classical stress response. Taken together, our findings expand the understanding of the MSTN system in Nile tilapia and provide evolutionary insight into its function.

Oxytocin Signaling Regulates the Homeostatic Response to Cold Stress in Poikilothermic Vertebrates

“…Hence, a reduction in the environmental temperature should induce a hypothalamic response that would change physiological and endocrine parameters, such as plasma levels of lactate, glucose and cortisol. To determine whether such homeostatic regulation occurs in fish hypothalamus, we dissected midbrains of Nile tilapia to include the diencephalon and optic tectum, which encompass all hypothalamic nuclei 38,39 ( Fig. 2a ).…”

“…Upregulated and downregulated genes expressed above 1 TPM in at least one condition were submitted to g:Profiler 41 for functional annotation analysis using O. niloticus as background. Real-Time PCR validation of selected genes was performed as previously described 38 . Briefly, possible genomic DNA contamination was eliminated by treatment with Invitrogen TURBO DNA-freeTM kit (Thermo Fisher Scientific, Vilnius, Lithuania) according to the manufacturer’s protocol.…”

“…Subsequently, plasma lactate, triglycerides and total protein content, as well as cortisol and growth hormone (GH) levels, were measured. Lactate, triglycerides and total protein were quantified using the Cobas c111 analyzer (Roche diagnostics GmbH, Mannheim Germany) as previously described by Segev-Hadar et al 38 . Cortisol and GH were quantified according to previously published protocols by Yeh et al 65 and Mizrahi et al 66 .…”

Genome Editing Using the CRISPR-Cas9 System to Generate a Solid-Red Germline of Nile Tilapia (Oreochromis niloticus)

“…XM_003451484) was performed using specific primer pairs (Table 1), as previously described. 31 Briefly, polymerase chain reaction (PCR) products were amplified using DreamTaq Green PCR Master Mix…”

Functional Characterization of the Almstn2 Gene and Its Association with Growth Traits in the Yellowfin Seabream Acanthopagrus latus (Hottuyn, 1782)

“…Starting with the fishery industry, inhibiting the expression of mstn is helpful for the management of muscle development in teleost fish, as well as for developing new policies to control the quality and production of meat. So far, numerous mstn genes have been identified in teleost fish, such as the gilthead seabream S. aurata [14], tilapia Oreochromis mossambicus [15], channel catfish Ictalurus furcatus [16], cyprinid loach Misgurnus anguillicaudatus [17], common carp Cyprinus carpio [18], zebrafish Danio rerio [19], rainbow trout Oncorhynchus mykiss [20], Japanese flounder Paralichthys olivaceus [21,22], yellowcheek carp Elopichthys bambusa [23], Atlantic salmon Salmo salar [24,25], mandarin fish Siniperca chuatsi [26], large yellow croaker Larimichthys crocea [27], grass carp Ctenopharyngodon idellus [28], Tibet fish Gymnocypris przewalskii [29], African lungfsh Protopterus annectens [30], pufferfish Takifugu bimaculatus [31], Nile tilapia Oreochromis niloticus [32], European sea bass Dicentrarchus labrax [33], and A. latus [34]. The functional identification of this gene lays the foundation for the genetic breeding of teleosts.…”