14.00 Nessim Kleiche (60 hec) An Ecotoxicological Study of Perfluoroctanoic Acid (PFOA) on a Teleost Fish: Oncorhynchus mykiss
Supervisor: Bethanie Carney Almroth (BioEnv, UGot)
Examiner: Ingela Dahllöf (BioEnv, UGot)
15.00 Maria Korzeniewska (45 hec) The use of non-invasive assays to evaluate the impacts of estradiol and the emerging environmental toxicant fluoxetine on fish scales
Supervisors: Joachim Sturve (BioEnv, UGot) and Patricia I Pinto (University of Algarve, Portugal)
Examiner: Ingela Dahllöf
Nessim Kleiche - An Ecotoxicological Study of Perfluoroctanoic Acid (PFOA) on a Teleost Fish: Oncorhynchus mykiss
PFOA, a chemical surfactant used in the plastic industry, has been known to be an endocrine disruptor in humans, but also recently discovered to disturb various biochemical and physiological parameters in aquatic species. This study aimed at finding out if current relevant level of FOA (relatively low compared to previous studies) in water poses a problem for the rainbow trout (Oncorhynchus mykiss). This was investigated with three fundamental analyses, first the evaluation of morphology and behavioral impairment with an open field activity, second the examination of blood indices and plasma Glucose and cortisol as stress markers and third the liver’s level of toxicity via enzymatic activity of GST (glutathione) and CAT (catalase). In order to do so, juvenile rainbow trout were fed PFOA spiked-feed through their daily diet within two distinct short- and long-term exposures. Hematological indices revealed unstressed fish in both exposures, and morphological confirmed a good welfare of rainbow trout within all treatments. The open field activity (only done on the chronic exposure), however, revealed a decreasing trend in all three measurements (Distance, velocity and acceleration) from a pre-post exposure-based analysis. Although, results were non-significant, decreasing trend were much more noticeable in the two treatments (50ng/g; 100ng/g), from before and after the 36 days exposure. Additionally, the activity of both enzymes (GST and CAT), showed no trend in both exposure in the different groups, although these results are to be taken with cautious considering methodology constraints in the liver samples. The PFOA range of 50 ng/g to 100 ng/g , even with long exposure, doesn’t accumulate enough to generate reactive oxygen species and thus antioxidant enzymes remain at baseline level; additionally, the detoxification process is not energy demanding enough to potentially impair behavior.. Overall, it seems that fish could possibly cope with current level of PFOA, however nothing can be said on the level of the harm done in the tissues, organs or blood.
Keywords: PFOA; fish; dietary; behavior; morphological; stress
Maria Korzeniewska - The use of non-invasive assays to evaluate the impacts of estradiol and the emerging environmental toxicant fluoxetine on fish scales
In recent years, in vitro approaches are gaining their momentum and this progress was mainly caused by the introduction of the new chemical regulations such as REACH in Europe. With REACH, there was an increased need for testing which implicated a boost in the use of testing animals that lead to questioning already existing concerns regarding in vivo tests and created the need for non-animal testing methodologies. The aim of this thesis was to investigate the impacts of estradiol and fluoxetine on fish scales using in vitro assays, using as endpoints of disruption 1) the scales activities of tartrate-resistant acid phosphate (TRAP) and alkaline phosphatase (ALP); 2) the quantification of several minerals in the scales and 3) selected transcript expression. Results showed that estradiol and fluoxetine cause change in enzymatic activities of TRAP and ALP and slightly elevated concentrations of minerals when compared to control groups. TRAP activity is considered to be an important marker for osteoclasts hence the extent of bone resorption while ALP activity is an enzyme marker for osteoblasts, linked to bone formation similarly to mammalian bone. Fish scales are mineralized structures whole mineral balance is met by the activity of both osteoblasts and osteoclasts, being TRAP and ALP also used as markers for their activity. However, in this study TRAP/ALP quantification was characterized by low sensitivity of the method which suggest a need for a new method to be developed or other endpoints tested.
Keywords: in vitro assays, fish scales, Tartrate-resistant acid phosphatase, Alkaline phosphatase, Estradiol, Fluoxetine