Osmoregulatory disturbance in Neotropical fish exposed to the crude extracts of the cyanobacterium, Radiocystis fernandoi.
Aquat Toxicol
; 216: 105315, 2019 Nov.
Article
en En
| MEDLINE
| ID: mdl-31561138
Blooms of cyanobacteria, a common event in eutrophic environments, result in the release of potentially toxic substances into the water. The cyanobacterium Radiocystis fernandoi produces microcystin (MC) and other peptides that may disturb homeostasis. This study evaluated the effect of intraperitoneal injections containing the crude extract (CE) of R. fernandoi strain R28 on the gills and kidneys of neotropical fish, Piaractus mesopotamicus, 3, 6 and 24â¯h post-injection. CE contained MC-RR, MC-YR and minor other oligopeptides. Plasma ions and the activities of the enzymes PP1 and PP2A, Na+/K+-ATPase (NKA), H+-ATPase (HA) and carbonic anhydrase (CA) were determined and morphological changes in both the gills and kidneys were characterized. Compared to controls, the concentration of Na+ within the plasma of P. mesopotamicus decreased after treatment with CE 3â¯h post treatment and increased after 24â¯h; the concentration of K+ decreased after 6â¯h. The activity of the endogenous PP1 and PP2A was unchanged in the gills and was inhibited in the kidneys 6â¯h after i.p. injection. In the gills, NKA activity increased after 3â¯h and decreased 6â¯h post i.p. exposure. Further, NKA activity did not differ from the controls 24-h post injection. In the kidneys, NKA, HA and CA activities were unaffected by treatment. The mitochondria-rich cell (MRC) density in the gills decreased after 3â¯h in the filament and 3 and 6â¯h in the lamellae and was restored to the control levels 24â¯h post-exposure. Filament epithelial hyperplasia and hypertrophy, lamellar atrophy and rupture of the lamellar epithelium were the most common effects of treatment in the gills. No histopathological changes occurred in the kidneys. This study demonstrates that a single dose of toxic CE from R. fernandoi can cause a transitory ion imbalance in P. mesopotamicus which is related to the changes in MRC levels and NKA activity. Ionic balance was recovered 24â¯h post i.p. injection, however, morphological changes that occurred in the gills took a longer amount of time to return to normal. To conclude, the effects of components contained within the CE of R. fernandoi may be harmful to P. mesopotamicus. In particular, the recovery of ionic regulation depends on MRC responses and histopathological changes produced by CE may affect gas exchange and other gill functions.
Palabras clave
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Cianobacterias
/
Mezclas Complejas
/
Exposición a Riesgos Ambientales
/
Characiformes
/
Osmorregulación
Límite:
Animals
Idioma:
En
Revista:
Aquat Toxicol
Asunto de la revista:
BIOLOGIA
/
TOXICOLOGIA
Año:
2019
Tipo del documento:
Article
País de afiliación:
Brasil
Pais de publicación:
Países Bajos