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Toxicological information

Genetic toxicity: in vivo

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Administrative data

Endpoint:
in vivo mammalian germ cell study: gene mutation
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference
Reference Type:
publication
Title:
Genotoxicity Testing of Some Metals in the Drosopila Wing Somatic Mutation and Recombination Test
Author:
Yesilada E
Year:
2001
Bibliographic source:
Bull Environ Contam Toxicol, 66: 464 - 469

Materials and methods

Principles of method if other than guideline:
In this study some metals have been subjected to the genotoxicity test, using somatic mutation and recombination test (SMART) in D. melanogaster. SMART test relies on wing spots of D. melanogaster and is a rapid, inexpensive in vivo assay, which detects genotoxic agent using somatic cells of a higher eukaryote. In the test, both somatic mutation and mitotic recombination are screened.
GLP compliance:
no
Type of assay:
other: Somatic mutation and mitotic recombination test in D. melanogaster

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Ba(NO3)2
- Substance type: metal nitrate compound
- Analytical purity: reagent grade

Test animals

Species:
Drosophila melanogaster
Strain:
other: virgin females (flr3/ln(3LR)TM3, rippsep bx34es ser); males from strain multiple wing hairs (mwh)
Sex:
male/female
Details on test animals and environmental conditions:
Eggs from crosses between the two strains were collected during 8 hours and the larvae were floated off the food in 17% NaCl 72±4 hours after. Groups of 25 larvae were transferred to individual glass vials containing 2 mL of the food with 500 µL of the test solution on the surface. The larvae developed in this medium until pupation.
The adult flies eclosing from the treatment vials were collected on days 10-12 after egg laying. The number of eclosions was also counted and the survival rate was calculated. From the eclosed adult flies only trans-heterozygous (mwh +/+ flr3) were collected and stored in 70% ethanol.

All experiments were conducted at 25±1°C and 60% relative humidity on cornmeal-agar medium.

Administration / exposure

Route of administration:
other: larvae are incubated in glasvials containing 2 mL of the food with 500 µL of the test solution on the surface
Vehicle:
- Vehicle(s)/solvent(s) used: ddH2O
Details on exposure:
Groups of 25 larvae were incubated in individual glass vials containing 2 mL of the food with 500 µL of the test solution on the surface.
Duration of treatment / exposure:
The larvae developed in the medium until pupation.
Frequency of treatment:
Once
Post exposure period:
The adult flies eclosing from the treatment vials were collected on days 10-12 after egg laying. The number of eclosions was counted and the survival rate was calculated.
Doses / concentrationsopen allclose all
Dose / conc.:
1 other: mM
Remarks:
nominal conc.
Dose / conc.:
10 other: mM
Remarks:
nominal conc.
No. of animals per sex per dose:
groups of 25 larvae were transferred to individual glass vials.
Control animals:
yes, concurrent vehicle
Positive control(s):
ethylmethanesulphonate: 20 mM aqueous solution

Examinations

Tissues and cell types examined:
From the eclosed adult flies only trans-heterozygous (mwh +/+flr3) were collected and stored in 70% ethanol. Their wings were mounted in Faure's solution (gum arabic 30 g, glycerol 20 mL, chloral hydrate 50 g and water 50 mL) and inspected under 500 X magnification to determine the spot size and their types.
Details of tissue and slide preparation:
The wings of adult flies eclosed from the treatment vials were mounted in Faure's solution (gum arabic 30 g, glycerol 20 mL, chloral hydrate 50 g and water 50 mL) and inspected under 500X magnification to determine the spot size and their types.
Evaluation criteria:
The observed wing hair spots were classified as small single spots, large single spots or twin spots. One or two mwh or flr mutant cells were scored as small single spots, three or more mwh or flr mutant cells as large single spots and neigboring mwh and flr mutant cells as twin spots. These 3 types of spots were evaluated separately. For the frequencies of spots per wing, a multiple-decision procedure was used to decide whether a result is positive, weakly positive, inconclusive, or negative.
Statistics:
The wing spot data of treated and control series were compared by conditional binominal test. Each statistical test was performed at the 5% significance level. The frequency of clone formation per 1E05 cells was determined, based on the number of wings analyzed, the number of mwh clones recorded (i.e., mwh single spots and the mwh parts of twin spots), and the number of cells scored in each wing (approx. 24 400, a standard number for analyzing induced somatic spots).

Results and discussion

Test results
Sex:
male/female
Genotoxicity:
positive
Remarks:
at a concentration of 10 mM: positive results for small single spots; inconclusive at low concentrations (1mM) for all types of spots
Toxicity:
yes
Remarks:
decrease in larval survival
Vehicle controls validity:
valid
Negative controls validity:
valid
Positive controls validity:
valid

Applicant's summary and conclusion

Conclusions:
In this somatic mutation and mitotic recombination study, positive results were found when high levels (10 mM) of barium nitrate were used; the results were inconclusive at low barium nitrate levels (1 mM).