Acronimo: MUGILSEX

Titolo: Mugil Cephalus (Linneus, 1758): the flathead grey mullet as a model for sex determination in fish with implications for aquaculture

Bando: PRIN

Durata: 31 mesi

Coordinatore: PROF. TOMASO PATARNELLO

Budget BCA: € 139.910,00

Responsabile scientifico: prof. Tomaso Patarnello

Research Team: Patarnello Tomaso

Abstract: "The overall objective of MUGILSEX is to unravel the mechanisms underpinning sex determination (SD) in the flathead grey mullet Mugil cephalus. There is an important gap in our knowledge of such mechanisms in fish, especially when genetic and environmental factors are both at play. M. cephalus, is a gonochoristic fish with genetic determination of sex, however, several cytogenetic studies showed that there is no evidence for heterochromatic sex chromosomes. Recently, our group (Ferraresso et al. 2021) reported for this species two missense SNPs at the follicle-stimulating hormone receptor (fshr) gene that are significantly associated with phenotypic sex and relevant for female development. We also showed in this specie incomplete penetrance of the effects of fshr mutations among geographic populations suggesting that different genomic backgrounds and/or different environmental conditions may play an important role in SD modulating the actions of the fshr locus. For these reasons the grey mullet is an interesting model to investigate the interplay between genetic and environmental factors - particularly temperature - in SD. Understanding the role of temperature is particularly relevant in a scenario of global warming. Noteworthy, mature female gonads are used to produce egg roe (“bottarga”), highly priced traditional food delicacy. The ability to control sex (e.g. obtaining an unbalanced sex ration toward females) and/or the development of non-lethal tools to sex individuals early on, might greatly benefit grey mullet farming. Moreover, M. cephalus is a species promising to increase sustainability of aquaculture as it is a low trophic, highly robust species, farmed/fished in artisanal fishery. There is also a specific knowledge gap in the husbandry of grey mullet particularly at the hatchery stage. Feeding strategy optimization related to environmental conditions is necessary to pursue more efficient aquaculture production. Among abiotic factors, temperature is the key environmental factor, playing a crucial role on metabolism, nutrient utilization, welfare and gut health.
The goals of this project are to:
a) assess the role of fshr locus and additional genetic loci in the grey mullet SD;
b) explore the role of temperature in the grey mullet SD;
c) generate female monosex (or female-bias) grey mullet farmed population;
d) pave the way for the development of applied tools for improving grey mullet farming.
To achieve these goals, we plan to:
1) re-sequence the genome of male and female M. cephalus samples (already available) searching for other loci relevant for SD in addition to fshr;
2) set up genetic-assisted breeding aimed at obtaining female monosex (or female-bias) F1;
3) set-up larval rearing experiments at different temperature to define the role of temperature in SD during larval development;
4) optimize grey mullet husbandry by estimating different protein/energy requirement under different water temperatures."