title: Characterization of the annual regulation of reproductive and immune parameters on the testis of European sea bass.
abstract: The European sea bass, Dicentrarchus labrax L., is a seasonal gonochoristic species, the males of which are generally mature during their second year of life. It has been demonstrated that cytokines and immune cells play a key role in the testicular development. This reproductive-immune interaction might be very important in the sea bass since several pathogens are able to colonise the gonad and persist in this tissue, altering further reproductive functions and spreading disease. This study aims to investigate the reproductive cycle of 1-year European sea bass males by analysing cell proliferation and apoptosis and the expression profile of some reproductive and immune-related genes in the testis, as well as the serum sex steroid levels. Our data demonstrate that, in 1-year-old European sea bass males, the testis undergoes the spermatogenesis process and that the reproductive and immune parameters analysed varied during the reproductive cycle. In the testis, the highest proliferative rates were recorded at the spermatogenesis stage, while the highest apoptotic rates were recorded at the spawning stage. We have also analysed, for the first time in European sea bass males, the serum levels of 17β-estradiol (E2) and dihydrotestosterone and the gene expression profile of the enzymes implied in their production, determining that at least E2 might be involved in the regulation of the reproductive cycle. Some immune relevant genes, including cytokines, lymphocyte receptors, and anti-viral and anti-bacterial molecules were detected in the testis of naïve European sea bass specimens, and their expression profile was related to the stages of the reproductive cycle, suggesting an important role for the defence of the reproductive tissues.
authors.affiliation: Centro Oceanográfico de Murcia, Instituto Español de Oceanografía (IEO), Carretera de la Azohía s/n., Puerto de Mazarrón, 30860, Murcia, Spain.
authors.forename: Yulema
authors.initials: Y
authors.lastname: Valero
authors.affiliation: Centro Oceanográfico de Murcia, Instituto Español de Oceanografía (IEO), Carretera de la Azohía s/n., Puerto de Mazarrón, 30860, Murcia, Spain.
authors.forename: Miriam
authors.initials: M
authors.lastname: Sánchez-Hernández
authors.affiliation: Centro Oceanográfico de Murcia, Instituto Español de Oceanografía (IEO), Carretera de la Azohía s/n., Puerto de Mazarrón, 30860, Murcia, Spain.
authors.forename: Alicia
authors.initials: A
authors.lastname: García-Alcázar
authors.affiliation: Department of Cell Biology and Histology, Faculty of Biology, Regional Campus of International Excellence "Campus Mare Nostrum", University of Murcia, 30100, Murcia, Spain.
authors.forename: Alfonsa
authors.initials: A
authors.lastname: García-Ayala
authors.affiliation: Department of Cell Biology and Histology, Faculty of Biology, Regional Campus of International Excellence "Campus Mare Nostrum", University of Murcia, 30100, Murcia, Spain.
authors.forename: Alberto
authors.initials: A
authors.lastname: Cuesta
authors.affiliation: Centro Oceanográfico de Murcia, Instituto Español de Oceanografía (IEO), Carretera de la Azohía s/n., Puerto de Mazarrón, 30860, Murcia, Spain. elena.chaves@mu.ieo.es.
authors.forename: Elena
authors.initials: E
authors.lastname: Chaves-Pozo
mesh_terms: D000818:Animals; D001492:Bass / Q000033:anatomy & histology*; D005399:Fishes / Q000033:anatomy & histology*; D006066:Gonads; D008297:Male; D012098:Reproduction / Q000502:physiology*; D013091:Spermatogenesis / Q000502:physiology; D013737:Testis / Q000502:physiology*
keywords: Cell renewal; European sea bass; Hormone levels; Immune factors; Testis