Single- and multi-species toxicity testing with nematodes.

2021 ◽  
pp. 298-322
Author(s):  
Sebastian Höss
Keyword(s):  
Caenorhabditis Elegans ◽  
Test Organism ◽  
Toxicity Testing ◽  
Single Species ◽  
Risk Assessments ◽  
Freshwater Sediments ◽  
Nematode Communities ◽  
Model Ecosystems ◽  
Test Organisms ◽  
Experimental Approaches

Abstract This chapter discusses the utility of nematodes in experimental ecotoxicology, and specifically in the study of freshwaters. Drawing on reports in which nematodes were used as test organisms in single-species tests as well as studies investigating nematode communities in model ecosystems (i.e. microcosms), the suitability of nematode-based experimental approaches in prospective and retrospective risk assessments of chemicals in freshwater sediments is examined. Several examples are presented of the use of Caenorhabditis elegans as a test organism in single-species bioassays, in order to demonstrate the versatility of this nematode for ecotoxicological investigations.

Toxicity of 39 MEIC Chemicals to Bioluminescent Photobacteria (The Biotox™ Test): Correlation with Other Test Systems

1994 ◽  
Vol 22 (3) ◽  
pp. 147-160 ◽  
Author(s):  
Anne Kahru ◽  
Barbara Borchardt
Keyword(s):  
Toxic Substance ◽  
Light Output ◽  
Test Organism ◽  
Toxicity Testing ◽  
Correlation Coefficients ◽  
Photobacterium Phosphoreum ◽  
Short Term ◽  
Freeze Dried ◽  
Light Loss ◽  
Test Correlation

Photobacterium phosphoreum are naturally luminescent marine bacteria, which emit light as a result of metabolism. Any damage to the cellular metabolism caused by a toxic substance can therefore be monitored by measuring the change in light output of the bacteria, the light loss being proportional to the degree of toxicity. The Biotox™ test, based on reconstituted freeze-dried (viable) Photobacterium phosphoreum as the test organism, was used for the short-term toxicity testing of 39 chemicals from the MEIC list. Concentration-effect curves for these 39 chemicals were measured and five-minute EC50 values (the concentration of chemical, mM, which reduces the light output of the bacteria by 50% after contact for five minutes) were calculated. The EC50 data from the Biotox test were correlated with data from the literature: octanol/water partition coefficients, EC50 data from the Microtox™ test, minimal inhibitory concentration values for Escherichia coli and Bacillus subtilis and acute toxicity data from animal and human cell lines, rodents and man. The correlation coefficients ranged between 0.63 and 0.93.

Bioaerosol Exposure Method for Package Integrity Testing†

1996 ◽  
Vol 59 (7) ◽  
pp. 768-771 ◽  
Author(s):  
SCOTT W. KELLER ◽  
JOSEPH E. MARCY ◽  
BARBARA A. BLAKISTONE ◽  
GEORGE H. LACY ◽  
CAMERON R. HACKNEY ◽  
...  
Keyword(s):  
Particle Size ◽  
Test Organism ◽  
Hole Diameter ◽  
Pseudomonas Fragi ◽  
Integrity Testing ◽  
Aerosol Exposure ◽  
Exposure Method ◽  
Test Organisms ◽  
Organism Growth ◽  
Bioaerosol Exposure

Test organism motility, concentration, aerosol exposure time, hole diameter and length were evaluated to determine their influence on microbial ingress into a flexible plastic pouch. Microtubes with 10- and 20-μm hole diameters and of 5- and 10-mm lengths were used as defects in 128 flexible pouches. A bioaerosol with a 2.68-μm mean particle size comprised of 102 or 106 CFU/ml source concentrations of motile or nonmotile Pseudomonas fragi TM 849 was introduced into a 119,911-cm3 chamber for exposures of 15 or 30 minutes. Six pouches showed test organism growth after a 72-h incubation period. Microbial ingress was significant (P < .05) for motile test organisms with source concentrations of 106 CFU/ml.

scholarly journals Evaluation of the Larvicidal Potential of the Leaf Extracts of Hyptis suaveolens Poit against Anopheles Mosquitoes

2018 ◽  
pp. 1-9
Author(s):  
Amaka, John I. ◽  
Attah, D. Daniel ◽  
Obisike, Victor U. ◽  
Benedict, Aboje G.
Keyword(s):  
Mosquito Control ◽  
Larval Instar ◽  
Test Organism ◽  
Phytochemical Screening ◽  
Leaf Extracts ◽  
Anopheles Mosquitoes ◽  
Lc50 Value ◽  
Hyptis Suaveolens ◽  
Test Organisms ◽  
Layer Chromatography

This study evaluated the larvicidal potential of the ethanolic and aqueous leaf extracts of Hyptis suaveolens Poit on the 4th larval instar of laboratory-reared Anopheles spp at varying concentrations of 0.1ml, 0.2ml, 0.3ml, 0.4ml and 0.5ml for specified periods of 24hrs, 48hrs and 72hrs. Qualitative phytochemical screening of the leaf extracts identified bioactive components like alkaloid, saponin, phenol, anthraquinone and flavonoid. The LC50 and LC90 values obtained indicate that the ethanolic leaf extracts of Hyptis suaveolens Poit had the greatest toxicity on the test organisms within 24hrs of exposure at median LC50 value of 0.485ml compared to the LC50 value of 0.625ml by its aqueous extract. The relative median potency estimates indicate that within 24 hrs, the ethanolic Hyptis suaveolens Poit was 0.161 times more potent on the test organism than aqueous Hyptis suaveolens Poit. The result of this research, therefore, underscores the efficacy of Hyptis suaveolens Poit as an eco-friendly alternative in Anopheles mosquito control. It is, therefore, recommended that quantitative phytochemical screening, application of column chromatography as well as thin layer chromatography be carried out on the extracts to isolate and purify toxic phytochemicals with larvicidal potentiality.

Hormesis - Implications for risk assessment caloric intake (body weight) as an exemplar

1998 ◽  
Vol 17 (8) ◽  
pp. 454-459 ◽  
Author(s):  
Angelo Turturro ◽  
Bruce Hass ◽  
Ronald W Hart
Keyword(s):  
Risk Assessment ◽  
Caloric Intake ◽  
Toxicity Testing ◽  
Risk Assessments ◽  
Specific Information ◽  
Response Curves ◽  
Hormetic Effect ◽  
The Impact ◽  
Hormetic Response

Hormesis can be considered as a parameter which has a non-monotonic relationship with some endpoint. Since caloric intake is such a parameter, and the impact of this parameter on risk assessment has been fairly well characterized, it can provide clues as to how to integrate the information from a hormetic parameter into risk assessments for toxicants. Based on the work with caloric intake, one could: (a) define a biomarker for hormetic effect; (b) integrate specific information on when in the animals lifespan the parameter is active to influence parameters such as survival; (c) evaluate component effects of the overall hormetic response; and (d) address the consequences of a non-monotonic relationship between the hormetic parameter and endpoints critical for risk assessment. These impacts on risk assessments have been characterized for chronic tests, but are also true for short-term tests. A priority is the characterization of the dose-response curves for hormetic parameters. This quantification will be critical in utilizing them in risk assessment. With this information, one could better quantitatively address the changes one expects to result from the hormetic parameter, and limit the uncertainty and variability which occurs in toxicity testing.

FUNGICIDAL ACTION AS AFFECTED BY INTERACTION OF NICKEL CHLORIDE, NABAM, ZINEB, AND ZINC SULPHATE

1961 ◽  
Vol 39 (3) ◽  
pp. 519-530 ◽  
Author(s):  
F. R. Forsyth ◽  
C. H. Unwin
Keyword(s):  
Zinc Sulphate ◽  
Early Blight ◽  
Fungicidal Activity ◽  
Test Organism ◽  
Brown Rot ◽  
Nickel Chloride ◽  
Fungicidal Action ◽  
Chloride Hexahydrate ◽  
Wettable Powder ◽  
Test Organisms

Protectant fungicidal action of mixtures of nabam, zineb, nickel chloride, and zinc sulphate was evaluated by means of a "microbeaker method" and the slide germination method, using as test organisms the fungi causing leaf rust of wheat, crown rust of oats, early blight of tomatoes, and brown rot of peaches. All of the fungicides tested were more effective against the two rusts than against the organisms causing early blight and brown rot. The relatively insoluble nickel ethylenebisdithiocarbamate was much less effective than the other chemicals tested. Ratios (w/w) of nickel chloride hexahydrate to zineb around unity and to nabam plus zinc sulphate from 2–10 to 1 showed an unfavorable effect on fungitoxic activity against urediospores of P. recondita. The ratio showing greatest antagonism varied, depending on the test organism used and whether or not tankmix or wettable powder zineb was used. The formation of nickel ethylenebisdithiocarbamate in the aqueous solution and its low fungicidal activity adequately explain the results obtained.

Marine Biosurfactants, III. Toxicity Testing with Marine Microorganisms and Comparison with Synthetic Surfactants

1991 ◽  
Vol 46 (3-4) ◽  
pp. 210-216 ◽  
Author(s):  
Knut Poremba ◽  
Wilfried Gunkel ◽  
Siegmund Lang ◽  
Fritz Wagner
Keyword(s):  
Marine Bacterium ◽  
Sea Water ◽  
Toxicity Testing ◽  
Test System ◽  
Marine Microorganisms ◽  
Oil Dispersants ◽  
Test Organisms ◽  
Pure Cultures ◽  
Microtox Test ◽  
Synthetic Surfactants

Eight synthetic and nine biogenetic surfactants were tested on their toxicity. Because of their possible application as oil dispersants against oil slicks on sea. the test organisms used were marine microorganisms (mixed and pure cultures of bacteria, microalgae, and protozoa). Bacterial growth was hardly effected or stimulated, whilst that of algae and flagellates was reduced. All substances tested were biodegradaded in sea water. The bioluminescence of Photobacter phosphoreum (Microtox test) was the most sensitive test system used. A ranking shows that most biogenetic surfactants were less toxic than synthetic surfactants. No toxicity could be detected with the glucose-lipid GL. produced by the marine bacterium Alcaligenes sp. MM 1.

Developing Automated Multispecies Biosensing for Contaminant Detection

1987 ◽  
Vol 19 (11) ◽  
pp. 73-84 ◽  
Author(s):  
E. L. Morgan ◽  
R. C. Young ◽  
C. N. Crane ◽  
B. J. Armigate
Keyword(s):  
Data Gathering ◽  
Toxicity Testing ◽  
Single Species ◽  
Water Quality Monitoring ◽  
Discrete Analog ◽  
Management Program ◽  
Computer Assisted ◽  
Aquatic Animal ◽  
Freshwater Species ◽  
Bioelectric Potentials

Automated biomonitoring may provide real-time functional information from cause/effect relationships between developing toxicity and a representative aquatic animal. However, since the applicability of single-species biomonitoring information may be subject to question when viewed in light of community toxicity and ecological quality control programs, we developed a computer-assisted multiple species biosensing system for water quality monitoring. In addition to fish, emphasis was placed on detecting species-specific bioelectric potentials produced by unrestrained mussels, burrowing mayfly nymph (Hexagenia spp.) and preliminary work with case building caddis fly larva. A specially designed differential amplifier was used for measuring bioelectric potentials induced from various activities of test subjects. Selected responses were detected as discrete analog signals, digitized and filed on computer disk. A management program provided various means for data gathering, filing and retrieval. Two pilot biomonitors were developed, each consisting of an instrumentation minicomputer with up to 12 biosensor input channels and various output peripherals including hardcopy and modem. These systems, combined with an IBM-XT personal computer based biomonitor interfaced to 24 multi-channel biosensor and physical parameter inputs, complete the present network. Results show that bioelectric signals generated from a variety of freshwater species may be easily monitored in a similar manner and viewed as representative measures in community toxicity testing.

Some Principles of Microbiological Turbidimetric Assays of Antibiotics

1979 ◽  
Vol 62 (4) ◽  
pp. 951-956
Author(s):  
Robert A Rippere
Keyword(s):  
Linear Response ◽  
Test Organism ◽  
Limited Range ◽  
Liquid Media ◽  
Agar Diffusion ◽  
Assay Procedure ◽  
Test Organisms ◽  
Effective Use

Abstract Turbidimetric methods for determining the potency of antibiotics are inherently more accurate and more precise than are comparable agar diffusion procedures, but assays conducted in liquid media are subject to degradation from less than ideal conditions to a much greater extent than are diffusion methods. The relationships between test organisms, antibiotics, and assay concentrations are discussed. A valid assay procedure must produce a linear response with an adequate slope (–0.4 to –1.2) by the test organism to increasing concentrations of drug; such linear response normally occurs over a limited range of concentrations. Criteria used to select photometers that offer the greatest advantages to analytical microbiologists are described, with guidelines for the most effective use of the chosen instrument.

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