Plectus acuminatus
Plectus acuminatus is widely abundant in many soils and has a parthenogenetic life cycle. After a prereproductive period of 3.5 weeks, females produce five to seven eggs per day for a period of 2 months at 20 degrees C. (ref. ID; 7023)
[ref. ID; 1276]
Test system
Acute toxicity
Strains
Samples were taken near Wageningen, The Netherlands.
Toxicants
Cadmium chloride (CdCl2), Pentachlorophenol.
Test design
LC50-tests were performed in water containing a defined mixture of minerals with concentrations resembling those found in interstitial water of sandy forest soils (K+: 0.1 mmol/L, Na+: 0.2 mmol/L, Ca2+: 0.35 mmol/L, Mg2+: 0.3 mmol/L, NH4+: 0.3 mmol/L, NO3-: 1.7 mmol/L, Cl-: 0.3 mmol/L) (Schouten and Van der Brugge 1989). pH 6.0+/-0.1.
Two replicates of the tests were carried out in multi-dishes (Greiner, 24 compartment plate, no. 662160) with lid and sealed with parafilm to minimize volatilization. Each compartment was filled with 0.9 ml of water containing toxicant. Samples of 0.1 ml of the multi-species suspension, containing 10-50 adult individuals of each species, were taken and suspended in each compartment. Temperature 20+/-0.1 degrees C in dark.
Measurements/observations
Mortality (24, 48, 72 and 96 hr).
Evaluations
LC50 according to the trimmed Spearmann-Karber method (Hamilton et al. 1977).
[ref. ID; 6936]
Test system
HSP60 as a potential biomaker of toxic stress
Strains
The strain was originally extracted from the top mineral layer of arable soil at Binnenhaven in Wageningen, The Netherlands.
Toxicants/concentrations
Heat stress (37 degrees C), Cd(Cl2) 0.007, 0.07, 0.7 mg/L and Cu(Cl2) 0.004, 0.04, and 0.4 mg/L.
Test design
Heat shock experiments were conducted in water where 110 females were kept at 20 degrees C (control, 24 hr) and 5 or 60 min at 37 degrees C. In a metal stress, 110 females were exposed for 2 hr at 20 degrees C.
Evaluations
HSP60, HSP70.
[ref. ID; 7023]
Test system
Toxicity test based on the Life-history strategy (3 weeks)
Strains
Nematodes were originally extracted from the top mineral layer of arable soil at the Binnenhaven in Wageningen, The Netherlands. Food is Acinetobacter johnsonion, a soil-inhabiting bacterium.
Toxicants/concentrations
Cadmium chloride (CdCl2 Cd2+: 0, 10, 32, 100, 320, and 1000 mg/kg dry wt.), Copper chloride (CuCl2/2H2O Cu2+: 0, 10, 32, 100, 320, and 1000 mg/kg dry wt.), Pentachlorophenol (0, 10, 18, 32, 56, and 100 mg/kg dry wt.).
Test design
Toxicity test were conducted in OECD artificial soil.
- Effect of pH: 3.5, 5.5, and 6.5. Temperature 20 degrees C, and soil moisture content 70% dry wt.
- Effect of temperature: 10, 15, and 20 degrees C +/- 0.1 degrees C. pH 5.5, and soil moisture content 70% dry wt.
- Effect of soil moisture content: 50, 60, and 70% dry wt. pH 5.5, and temperature 20 degrees C.
A suspension of A. johnsonion was added in all treatments, obtaining a final density of 2x10E9 cells/g dry wt. Artificial soil (5.0 g dry wt.) was inoculated with nematodes (50 adults females, 4 weeks old). After 3 weeks nematodes were extracted from the soil by means of a decanting method modified from Cobb. 2 replicates, in the dark.
Toxicity test: 100 nematodes were transferred to 5.0-g dry wt. artificial soil in a Petri dish (6-cm diameter). A suspension of A. johnsonion was added to all treatments to obtain a final density of 2X10E9 cells/g dry wt. 2 replicates. Experimental conditions were temperature 20 degrees C, moisture content 70% dry wt., and pH(KCl)=5.5.
Measurements/observations
Number of juveniles and adults.
Evaluations
Juveniles to adults ratio, EC50, and NOEC.
[ref. ID; 7025]
Test system
Phenotypic plasticity vs. concentration-response relationships
Strains
Toxicants
CuCl2/2H2O
Test design
The water used for culturing and experiments contained a defined mixture of minerals resembling those found in intestitial water of sandy forest soil. pH 6.0+/-0.1.
Life-cycle studies were conducted in agar in multicompartment plates (Greiner 662160). Agar droplets (70 ul, 0.5%) were applied on the inside of the lid. Acinetobacter johnsonion (2x10E8 cells/ml). Each compartment of the bottom plate contained 1 ml water, and plates were sealed with Parafilm to prevent evaporation. 0, 9.7, 17.5, 31.4, 56.6, and 101 uM copper in agar.
Eggs were individually transffered to the agar droplets. 48 replicates per each concentration.
Measurements/observations
Juvenile survival and period. Daily reproduction and reproductive period. Fitness.
Evaluations
EC20 using nonlinear regression procedures as described in Bruce and Versteeg.