Germ cell proliferation and apoptosis during testicular regression in a seasonal breeding fish kept in captivity.

Cell proliferation and apoptosis regulate germ cells stock and sperm production, eliminate anomalous gametes, and are essential parameters to consider in fish farming. Herein, spermatogenic activity as well as germ cell proliferation and apoptosis were assessed in Leporinus taeniatus, a seasonal breeding species from the São Francisco River basin, Brazil. Testes of 24 adult fishes from a farming station were sampled between December and July and processed for light and transmission electron microscopy and immunohistochemistry for PCNA and TUNEL assay. The gonadosomatic index and seminiferous tubule diameters presented higher values during the breeding season (December/January and February/March), and then significantly reduced during the regression and resting stages (April/May and June/July). Phagocytosis of spermatozoa by Sertoli cells was evident during gonadal regression, but a significant number (up to 30%) remained at the tubular lumen during the resting stage. A higher PCNA/TUNEL ratio occurred in the breeding period, leading to an elevated proportion (%) of spermatogonia (GA and GB) in resting. Moreover, a higher TUNEL/PCNA ratio indicates the contribution of apoptosis to the reduction of germ cells during testicular regression. Together, these results indicate a shift in the balance between cell proliferation and apoptosis that contributes to the regulation of the spermatogenic cycle and germ cells pool of L. taeniatus kept in captivity.

Length-weight relationship and reproductive activity of the Leporinus piau Fowler, 1941 captured in a small deactivated hydropower plant / Relação peso-comprimento e atividade reprodutiva do Leporinus piau Fowler, 1941, capturados em uma pequena usina hidrelétrica desativada

Reproductive activity of 'piau gordura' Leporinus piau was studied using biometric, macroscopic and microscopic analysis. A total of 74 specimens of L. piau were collected quarterly from January to December 2005 in a small deactivated hydropower plant located at Jorge Pequeno Stream and preserved in a fixative solution until analysis. The alterations after fixation were evaluated. The stages of gonadal maturation were determined by histology and gonadosomatic index (GSI). The females and males in the spawning capable and regressing stage were registered from October to December. L. piau is total spawning and the HSI (hepatossomatic index), SRI (stomach repletion index) and CFI (coelomic fat index) of females and males did not showed a statistical difference. However they were numerically different between the stages of maturation. For both sexes, the smallest specimens captured during the reproductive activity have measured around 8.3 cm in total standard. The length-weight relationship observed for the parameter 'b' was 3.01 and the parameter 'a' was 0.02. This study demonstrates the importance of Jorge Pequeno Stream in the reproductive activity of migratory fish in the upper São Francisco river.

A atividade reprodutiva do 'piau-gordura' Leporinus piau foi estudada, utilizando análises biométricas, macroscópicas e microscópicas. Um total de 74 exemplares de L. piau foram capturados trimestralmente de janeiro a dezembro de 2005 em uma pequena usina hidrelétrica desativada localizada no Ribeirão Jorge Pequeno e fixados até as análises biométricas e histológicas. As alterações após fixação foram avaliadas. Os estádios de maturação gonadal foram determinados por histologia e índice gonadossomático (IGS). As fêmeas e os machos capazes de desovar foram registrados de outubro a dezembro. L. piau possui desova total e os índices IHS (índice hepatossomático), IRS (índice de repleção estomacal) e IGC (índice de gordura celômica) de fêmeas e machos não apresentaram diferença estatística apesar de numericamente serem diferentes entre os estádios de maturação. Os menores exemplares capturados em atividade reprodutiva mediram 8,3 cm de comprimento total para ambos os sexos. Na análise da relação peso-comprimento, o parâmetro 'b' foi 3,01 e o parâmetro 'a' foi de 0,02. Este estudo fornece importantes informações sobre L. piau e sugere o papel do Ribeirão Jorge Pequeno na atividade reprodutiva de peixes na região do alto rio São Francisco.