The meagre Argyrosomus regius (Asso, 1801) is a promising emerging aquaculture species. The use of recombinant gonadotropins to induce gametogenesis in sexually immature fish has the potential to reduce the generation time for selective breeding programmes of aquaculture species that reach first maturity at large size, such as the meagre (1-3). The aim of this work was to assess the effects that a six-week recombinant follicle stimulating hormone (rFsh) administration had on germ cell proliferation and apoptosis in sexually immature meagre. Sexually immature male meagre (18 months of age) reared in indoor tanks at the Institute of Agrifood Research and Technology (IRTA; Sant Carles de la Ràpita, Tarragona Spain) underwent weekly treatments with increasing doses of rFsh (week 0: 6 µg/kg; week 1: 9 µg/kg; week 2 to week 6: 12 µg/kg). Control fish were treated with physiological saline solution. Fish were sacrificed at week 0 (6 control fish) and week 6 (9 control and 4 rFsh-treated fish). For each fish, body mass (BM) and testis mass (TM) were measured and relative testis mass (gonadosomatic index) was calculated as GSI = 100×TM/BM. Testis samples were fixed in Bouin’s solution, dehydrated in ethanol and embedded in paraffin wax. Proliferating and apoptotic germ cells were identified on histological sections through the immunohistochemical detection of the proliferating cell nuclear antigen (PCNA) and the terminal deoxynucleotidyl transferase-mediated 2’-deoxyuridine 5’-triphosphate nick end labeling (TUNEL) method, respectively. The density of anti-PCNA–positive single spermatogonia and anti-PCNA–positive spermatocysts (i.e., spermatogenic cysts containing spermatogonia or primary spermatocytes), as well as the surface occupied by TUNEL-positive apoptotic cells, were measured on randomly selected fields of testicular sections. Statistical differences for all the analysed parameters were evaluated by a 2-tailed Student’s t test. Fish treated with rFsh displayed significantly higher GSI, significantly lower surface occupied by apoptotic cells and significantly higher density of anti-PCNA positive spermatocysts compared to both controls. The present results suggest that, in sexually immature meagre, apoptosis plays a major role in removing spermatogonia that cannot proceed towards meiosis. Treatment with rFsh supported survival and proliferation of spermatogonia as well as spermatogonial entry into meiosis. In conclusion, the administration of increasing doses of rFsh proved to be effective as a first step of a treatment protocol to induce precocious puberty in meagre. Financial grant provided by the European Union´s Programme H2020 (GA 862658, NewTechAqua).
MALE GERM CELL PROLIFERATION AND APOPTOSIS IN SEXUALLY IMMATURE MEAGRE (ARGYROSOMUS REGIUS) TREATED WITH RECOMBINANT FOLLICLE STIMULATING HORMONE
Rosa Zupa;Chrysovalentinos Pousis;Letizia Passantino;Aldo Corriero
2022-01-01
Abstract
The meagre Argyrosomus regius (Asso, 1801) is a promising emerging aquaculture species. The use of recombinant gonadotropins to induce gametogenesis in sexually immature fish has the potential to reduce the generation time for selective breeding programmes of aquaculture species that reach first maturity at large size, such as the meagre (1-3). The aim of this work was to assess the effects that a six-week recombinant follicle stimulating hormone (rFsh) administration had on germ cell proliferation and apoptosis in sexually immature meagre. Sexually immature male meagre (18 months of age) reared in indoor tanks at the Institute of Agrifood Research and Technology (IRTA; Sant Carles de la Ràpita, Tarragona Spain) underwent weekly treatments with increasing doses of rFsh (week 0: 6 µg/kg; week 1: 9 µg/kg; week 2 to week 6: 12 µg/kg). Control fish were treated with physiological saline solution. Fish were sacrificed at week 0 (6 control fish) and week 6 (9 control and 4 rFsh-treated fish). For each fish, body mass (BM) and testis mass (TM) were measured and relative testis mass (gonadosomatic index) was calculated as GSI = 100×TM/BM. Testis samples were fixed in Bouin’s solution, dehydrated in ethanol and embedded in paraffin wax. Proliferating and apoptotic germ cells were identified on histological sections through the immunohistochemical detection of the proliferating cell nuclear antigen (PCNA) and the terminal deoxynucleotidyl transferase-mediated 2’-deoxyuridine 5’-triphosphate nick end labeling (TUNEL) method, respectively. The density of anti-PCNA–positive single spermatogonia and anti-PCNA–positive spermatocysts (i.e., spermatogenic cysts containing spermatogonia or primary spermatocytes), as well as the surface occupied by TUNEL-positive apoptotic cells, were measured on randomly selected fields of testicular sections. Statistical differences for all the analysed parameters were evaluated by a 2-tailed Student’s t test. Fish treated with rFsh displayed significantly higher GSI, significantly lower surface occupied by apoptotic cells and significantly higher density of anti-PCNA positive spermatocysts compared to both controls. The present results suggest that, in sexually immature meagre, apoptosis plays a major role in removing spermatogonia that cannot proceed towards meiosis. Treatment with rFsh supported survival and proliferation of spermatogonia as well as spermatogonial entry into meiosis. In conclusion, the administration of increasing doses of rFsh proved to be effective as a first step of a treatment protocol to induce precocious puberty in meagre. Financial grant provided by the European Union´s Programme H2020 (GA 862658, NewTechAqua).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
