Effects of Bisphenol A on redox balance in red blood and sperm cells and spermatic quality in zebrafish Danio rerio

Bisphenol-A (BPA) is a potential endocrine disruptor besides being associated with oxidative damage in several vertebrate classes. In the present study we investigated oxidative effects in erythrocytes and sperm cells as well as spermatic quality in Danio rerio exposed to 14 days at BPA concentrations of 2, 10 and 100 μg/L. Organelles structure, reactive species of oxygen (ROS) and lipoperoxidation (LPO) on erythrocytes and sperm cells were measured by flow cytometry and spermatic parameters were analyzed by the computer-assisted sperm analysis (CASA) system. For both cell types, when compared with control BPA treatment induced a significant increase in ROS and LPO production causing the membrane fluidity disorder, loss of membrane integrity and mitochondrial functionality. Furthermore, it was found a significant increase in DNA fragmentation in erythrocytes of zebrafish BPA exposed. Regarding the spermatic quality, results showed lower sperm motility in animals exposed to BPA, and alterations on velocity parameters of spermatozoa. Thus, the present study concludes that BPA affects the oxidative balance of both cell types, and that can directly affects the reproductive success of the adult Danio rerio. The sensitivity of erythrocytes to oxidative damage induced by BPA was similar to sperm cells, indicating a potential use of blood cells as indicators of oxidative damage present in fish sperm.

Immune adaptive response induced by Bicotylophora trachinoti (Monogenea: Diclidophoridae) infestation in pompano Trachinotus marginatus (Perciformes: Carangidae)

Fish have developed protective strategies against monogeneans through immunological responses. In this study, immune adaptive response to parasites was analysed in the pompano Trachinotus marginatus infested by Bicotylophora trachinoti. Hosts were pre-treated with formalin and after 10 days assigned to one of the following experimental treatments: (1) fish infested with remaining eggs of B. trachinoti; (2) fish infested with remaining eggs of B. trachinoti and experimentally re-infested by exposure to T. marginatus heavily infested with B. trachinoti. Samples were collected at 0, 15, and 30 days. Gills were dissected to check the presence of B. trachinoti. Blood was collected for haematological and biochemical assays. Spleen and head-kidney were dissected for phagocytosis assay. The spleen-somatic index was also calculated. Re-infested fish showed a faster and higher parasite infestation than infested ones. The parasite mean abundance at 15 days was 24.86+/-13.32 and 11.67+/-8.57 for re-infested and infested fish, respectively. In both groups, hosts showed an immune adaptive response to parasite infestation that was marked by an increased number of leukocytes. Also, phagocytosis (%) in spleen and head-kidney cells was stimulated after parasite infestation (92.50+/-3.73 and 66.00+/-9.54, respectively), becoming later depressed (77.39+/-6.69 and 53.23+/-9.14, respectively). These results support the hypothesis that monogenean infestation induces a biphasic response of the non-specific defence mechanisms in the pompano T. marginatus. This response is marked by an initial stimulation followed by a later depression of the non-specific defence mechanisms.