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Insights on the seasonal variations of reproductive features in the Eastern Atlantic Bluefin Tuna2.83 MB
Accepted VersionCC BY-NC-ND V4.0, Open Access
Journal article
Insights on the seasonal variations of reproductive features in the Eastern Atlantic Bluefin Tuna
General and Comparative Endocrinology, Vol.282, 113216
2019
Abstract
The Atlantic Bluefin tuna (ABFT, Thunnus thynnus) is one of the most intensely exploited fisheries resources in the world. In spite of the years of studies on ABFT, basic aspects of its reproductive biology remain uncertain. To gain insight regarding the seasonal changes of the reproductive characteristics of the eastern stock of ABFT, blood and tissue samples were collected from mature specimens caught in the Mediterranean basin during the reproductive (May-June) and non-reproductive season (Oct-Nov). Histological analysis of the gonads of May-June samples indicated that there were females which were actively spawning (contained post-ovulatory follicles) and females that were not actively spawning that had previtellogenic and fully vitellogenic oocytes. In males, testis were at early or late stage of spermatogenesis during the reproductive season. In Oct-Nov, ovaries contained mostly previtellogenic oocytes as well as beta and alpha atretic follicles while the testis predominantly contained spermatogonia and few cysts with spermatocytes and spermatozoa. Gonadosomatic index (GSI) in females was highest among the actively spawning individuals while in males GSI was higher in early and late spermatogenic individuals compared to those that were spent. Plasma sex steroids levels varied with the reproductive season. In females, estradiol (E2), was higher in May-June while testosterone (T) and progesterone (P) did not vary. In males, E2 and T were higher in May-June while P levels were similar at the two sampling points. Circulating follicle stimulating hormone (FSH) was higher in Oct-Nov than in May-June both in males and females. Vitellogenin (VTG) was detected in plasma from both males and females during the reproductive season with levels in females significantly higher than in males. VTG was undetected in Oct-Nov samples. Since choriogenesis is an important event during follicle growth, the expression of three genes involved in vitelline envelope formation and hardening was measured and results showed significantly higher levels in ovaries in fish caught in May-June with respect to those sampled in Oct-Nov. In addition, a set of genes encoding for ion channels that are responsible for oocyte hydration and buoyancy, as well as sperm viability, were characterized at the two time points, and these were found to be more highly expressed in females during the reproductive season. Finally, the expression level of three mRNAs encoding for different lipid- binding proteins was analyzed with significantly higher levels detected in males, suggesting sex-specificity of their expression. Our findings provide additional information on the reproductive biology of ABFT, particularly on biomarkers for the assessment of the state of maturation of the gonad, highlighting gender-specific signals and seasonal differences.
Details
- Title
- Insights on the seasonal variations of reproductive features in the Eastern Atlantic Bluefin Tuna
- Authors
- Oliana Carnevali (Author) - Università Politecnica delle March, ItalyFrancesca Maradonna (Author) - Università Politecnica delle March, ItalyAndrea Sagrati (Author) - Università Politecnica delle March, ItalyMichela Candelma (Author) - Università Politecnica delle March, ItalyFrancesco Lombardo (Author) - Università Politecnica delle March, ItalyPaolo Pignalosa (Author) - OCEANIS Srl, ItalyErica Bonfanti (Author) - University of the Sunshine CoastJosephine N Nocillado (Author) - University of the Sunshine CoastPeter Palma (Author) - University of the Sunshine CoastGiorgia Gioacchini (Author) - Università Politecnica delle March, ItalyAbigail Elizur (Author) - University of the Sunshine Coast
- Publication details
- General and Comparative Endocrinology, Vol.282, 113216; 9
- Publisher
- Academic Press
- Date published
- 2019
- DOI
- 10.1016/j.ygcen.2019.113216
- ISSN
- 0016-6480; 0016-6480
- Copyright note
- Copyright © 2019. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/
- Organisation Unit
- School of Science and Engineering - Legacy; University of the Sunshine Coast, Queensland; GeneCology Research Centre - Legacy; School of Science, Technology and Engineering; Centre for Bioinnovation
- Language
- English
- Record Identifier
- 99451418302621
- Output Type
- Journal article
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