Methods Introduction The effects of Triclosan on the metabolism of

The effects of Triclosan on the metabolism of
developing sheepshead minnow (Cyprinodon
variegatus) larvae.
Lallemand Lise1, Voisin Anne-Sophie2, Darchambeau François3, Das Krishna4, Schnitzler Joseph4
1 Master 1 Ecophysiologie/Ecotoxicologie, Université Pierre et Marie Curie, France
2 Laboratory of evolutionary and Adaptive Physiology-URBE, Université de Namur, Belgique
3 Unité d’Océanographie Chimique, Université de Liège, Belgique
4 Laboratoire d’Océanologie, Université de Liège, Belgique
Methods
Introduction
•  Study model: Cyprinodon variegatus (fig 1).
•  I n d i v i d u a l s w e re ex p o s e d t o TC S
concentrations of 20, 50 and 100μg/L.
•  Measurements were conducted on larvae
at 15 and 30 dph.
•  Measurement of O 2 consumption by
respirometry (fig. 2).
•  Assay of antioxidant enzymes (Glutathion
re d u c t a s e ( G R ) a n d G l u t a t h i o n - S transferase (GST).
The aquatic environment repesents the final sink for
many chemicals including bactericidal agents.
Among them Triclosan (TCS) has been shown to
affect the thyroid system of teleosts. Thyroid
hormones are involved in the control of metabolism,
so changes in hormone levels induced by triclosan
may affect respiratory rates and antioxidant stress in
exposed fish.
Two research questions are put forward :
-  Does TCS have an effect on respiratory rates ?
-  Is there a change in activity of enzymes involved in
the management of oxidative stress ?
Fig 2: Respiratory rates
mesure.
Fig 1: Cyprinodon variegatus.
35
30 dph
35
30
900
30
25
25
20
20
*
15
10
*
*
15
10
5
5
0
0
contro
l
GR à 30 dph
CS
TCS-20
TCS-50
TCS-100
*
800
Fig 4: Activity of GR and GST at 30
dph (mean ± SD). There is at least a
significant difference (p<0,05)
between the control and the
conditions (*).
700
600
500
400
300
200
100
0
CS
TCS-20
Fig 3: Respiration rate at 15 and 30 dph (mean ± SD). There are at least a significant difference
(p<0,05) between control and conditions (*).
à Respirometry showed that TCS decreased the metabolism at 15 dph,
whereas no differences in respiration rate could be observed between
control and exposed larvae at 30 dph (fig. 3).
à At 15 dph no difference was observed for any of the antioxidant enzymes.
à At 30dph a sharp increase in the activity of GR was observed between the
control ans TCS exposed fish. The activity of GST remained stable (fig. 4).
TCS-50
GST units/mg protein
15 dph
GR units/mg protein
Respiration in nmol/mgDW/h
Results
TCS-100
GST à 30 dph
16000
14000
12000
10000
8000
6000
4000
2000
0
CS
TCS-20
TCS-50
TCS-100
Discussion
à Thyroid hormones are major factors controlling the metabolic rate related to respiration and oxidative stress.
à TCS reduced the metabolism at 15 dph that corresponds to the moment where larvae to juvenile transition of
sheepshead minnows occur.
à Previous experiments showed that TCS induces an increase in thyroid hormone concentrations (Benichou,
2014 & Rahmouni, 2014) and that hyperthyroidism (Villanueva & al. 2013) may induces oxidative stress.
à Increase of antioxidant protection mechanisms could be a way to compensate oxidative stress.
à The changes in GR activity observed at 30 dph may also be related to the reduced metabolism at 15 dph.
INTERFACULTARY CENTER FOR MARINE RESEARCH – LIEGE UNIVERSITY