This study evaluated the effects of perfluorooctanesulfonic acid (PFOS), NPK mineral
fertilizer, and their combinations on survival, embryonic development, and molecular
responses in rainbow trout (Oncorhynchus mykiss). Fertilized eggs obtained from five
females were exposed to PFOS (0–2000 ng/mL), NPK (0–150 µg/mL), and their
combinations. Survival, daily mortality, development, hatching, and developmental
abnormalities were monitored. Reverse-transcription quantitative PCR (RT-qPCR) was
used to determine the relative expression of the gpx1α, gpx1β, tnf-α, and il-1β genes in
hatched larvae. NPK caused the most pronounced direct physiological stress,
particularly at 150 µg/mL, which was associated with increased egg mortality,
developmental abnormalities, and hatching failure. The physiological stress was
especially pronounced in the group exposed to 200 ng/mL PFOS and 150 µg/mL NPK.
PFOS did not cause a simple concentration-dependent decrease in survival; the
apparently higher survival observed in some groups was accompanied by developmental
delay, reduced vitality, and delayed hatching. Molecular responses were not uniform
and differed among females. In female D, increasing PFOS concentrations in the
presence of 50 µg/mL NPK reduced the expression of gpx1α and gpx1β, with a similar
pattern observed for tnf-α; no statistically significant differences were detected for il1β. Owing to the differences among females, a consistent synergistic effect of the two
stressors could not be confirmed. These results demonstrate that survival alone does not
capture all consequences of exposure and should therefore be evaluated together with
developmental, physiological, and molecular indicators.
|
