Protocol for Acute and Chronic Ecotoxicity Testing of the Turquoise Killifish Nothobranchius furzeri

Summary

In this work, we describe an acute, chronic and multigenerational bioassay to study the effects of single and combined stressors on the Turquoise killifish Nothobranchius furzeri. This protocol is designed to study life-history traits (mortality, growth, fecundity, weight) and critical thermal maximum.

Abstract

The killifish Nothobranchius furzeri is an emerging model organism in the field of ecotoxicology and its applicability in acute and chronic ecotoxicity testing has been demonstrated. Overall, the sensitivity of the species to toxic compounds is in the range with, or higher than, that of other model species.

This work describes protocols for acute, chronic, and multigenerational bioassays of single and combined stressor effects on N. furzeri. Due to its short maturation time and life-cycle, this vertebrate model allows the study of endpoints such as maturation time and fecundity within four months. Transgenerational full life-cycle exposure trials can be performed in as little as 8 months. Since this species produces eggs that are drought-resistant and remain viable for years, the on-site culture of the species is not needed but individuals can be recruited when required. The protocols are designed to measure life-history traits (mortality, growth, fecundity, weight) and critical thermal maximum.

Introduction

Sensitivity profiles of an array of species to strategically selected toxicants have been described¹ for the European REACH legislation (Registration, Evaluation, Authorization, and Restriction of Chemicals). Acute or short-term toxicity tests were mostly used for this purpose as they give a quick indication of a species' sensitivity. However, in their natural environment, organisms are exposed over much longer periods and full life-cycles or even several generations could be affected². Moreover, organisms in polluted environments are typically exposed to more than one stressor at a time, which may interact with each....

Protocol

All methods described here have been approved by the Ethical committee of KULeuven.

1. Hatching and General Maintenance of N. furzeri

1. Prepare fish medium (pH 7) at a temperature of 14 °C and add purified Type II water, with added standardized salts, to a conductivity of 600 µS/cm (24 °C).
2. Select eggs from the GRZ (Gona-Rhe-Zhou) laboratory line that have been stored under standardized conditions¹³. Select eggs in the DIII stage (i.e. ready to hatch), recognizable by the presence of golden eyes⁹ and gently transfer them with a soft pair of....

Results

The results of the acute exposure of N. furzeri to different concentrations of copper, calculated as in 2.5.2, show cleardose-response relationships (Figure 1). There is an increase in mortality with increasing toxicant concentration. LC₅₀ values decrease over time, meaning that with decreasing concentrations, more time passes before 50% of the replicates die. For detailed results on the acute and chronic exposure of N. furzeri to.......

Discussion

This work describes a new bioassay using Nothobranchius furzeri, an emerging model organism, to study the individual and combined long-term effects of toxicants and other stressors. The presented protocols were successfully applied to measure the sensitivity of the species to an array of toxicants (copper, cadmium, 3,4-dichloroaniline, and chlorpyrifos). Due to its fast life-cycle, this vertebrate model allows for assessment of sublethal and transgenerational effects within four months. Another major advantage o.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
purified water Type 1 (milli Q)	Millipore
Sea Salt	Instant Ocean
2L plastic tank	SAVIC		Always separate material for control and toxicity treatments
1L plastic tank (spawning)	Avamoplast		Always separate material for control and toxicity treatments
nets	Aqua bilzen		Always separate material for control and toxicity treatments
2L glass jars	Sepac-Flacover		Always separate material for control and toxicity treatments
0,5L glass jars	Sepac-Flacover		Always separate material for control and toxicity treatments
Artemia eggs	Ocean Nutrition
chironomus	Ocean Nutrition		frozen
tricaine	Sigma aldrich
petri dishes	VWR
Parafilm	VWR
pipettes	MLS
tweezers	FST
500 µm mesh sieve	/		self-made
microcentrifuge tube (2ml)	BRAND		To store fish in freezer
glass vials	Sigma aldrich		For water analysis
weighing boat	MLS
Jiffy 7c pellets	Jiffy
water bath	Gilac		for Ctmax
liquid nitrogen	Air liquide
digital thermometer	Testo AG	testo 926
HETO therm heater	Anker Schmitt
calibrated balance	Mettler-Toledo AG
camera	/
platform for camera	/		self-made
Multiparameter kit	HACH
Freezer (-80°C)	Panasonic Ultra low temperature freezer
Name	Company	Catalog Number	Comments
Fysio
homogenisation buffer	VWR		0.1 M TRIS–HCl, pH 8.5, 15 % polyvinyl pyrrolidone, 153 µM MgSO4 and 0.2 % Triton X-100
chloroform:methanol	Sigma Aldrich
glyceryl tripalmitate	Sigma Aldrich
amyloglucosidase	Sigma Aldrich	A7420
glucose assay reagent	Sigma Aldrich	G3293
Biorad protein dye	VWR
96-well microtiter plate	Greiner Bio-one
384 microtiter plates	Greiner Bio-one
2 ml glass tubes	Fiers		For fat analysis
2,5ml eppendorf tubes	VWR
homogeniser	Ultra-turrax TP 18/10
photospectrometer	Infinite M200 TECAN
heater for glass tubes	Hach COD REACTOR
centrifuge	Eppendorf Centrifuge 5415 R
Incubator	Bumako