David B . Dusenbery

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The acute lethality of the salts of eight metals--HgCl2, BeSO4.4H2O, Al(NO3)3.9H2O, CuCl2.2H2O, ZnCl2, Pb(NO3)2, CdCl2, and Sr(NO3)2--was determined using a type of free-living nematode, Caenorhabditis elegans. The LC50 values were compared to the published mammalian oral LD50 values for salts of the same metals. Within this set of chemicals, C. elegans was(More)
This study describes a new approach for assessing behavioral changes following toxicant exposure and compares the method to other common endpoints used in environmental toxicology. The nematode Caenorhabditis elegans was exposed to a range of ethanol concentrations to determine its effect on survival, reproduction and behavior. Each endpoint was evaluated(More)
Total luminescence spectroscopy was employed to characterize and quantitate age-related changes in fluorescence in the nematode Caenorhabditis elegans, an established model for aging research. The excitation wavelength was varied between 250 and 590 nm in 10-nm increments. At each excitation wavelength, the emission wavelength was varied between 300 and 600(More)
The technique of countercurrent separation has been used to isolate 17 independent chemotaxis-defective mutants of the nematode Caenorhabditis elegans. The mutants, selected to be relatively insensitive to the normally attractive salt NaCl, show varying degrees of residual sensitivity; some are actually weakly repelled by NaCl. The mutants are due to single(More)
Formulas are derived for the effect of size on a free-swimming microbe's ability to follow chemical, light, or temperature stimuli or to disperse in random directions. The four main assumptions are as follows: (i) the organisms can be modeled as spheres, (ii) the power available to the organism for swimming is proportional to its volume, (iii) the noise in(More)
Four mutant strains of the nematodeCaenorhabditis elegans previously isolated as defective in thermotaxis (Hedgecock and Russell, 1975) were compared to the wild type in tests of their thermal range of activity and chemotaxis. The cold side of the temperature-activity curves of all four strains were different from wild type. The curves of the two cryophilic(More)
Diploptera punctata, a Pacific islands cockroach, discharges a fine aerosol ofp-benzoquinones from a pair of tracheal glands in response to disturbance or CO2 anesthesia. In addition, the glands and their contents are shed at each molt. We measured the amount ofp-benzoquinones discharged in response to pinching and anesthesia and the filling of glands after(More)
A computer tracking system was used to quantify the responses of infective second-stage juveniles of the plant-parasitic nematodeMeloidogyne incognita to carbon dioxide. A sudden increase in concentration caused an increase in the rate of locomotion and a decrease in the frequency of changes of direction. The threshold was about 0.01 % vol CO2/vol gas when(More)
Predictions of the minimal size an organism must have to swim along stimulus gradients were used to compare the relative advantages of sensory systems employing spatial (simultaneous) and temporal (sequential) gradient detection mechanisms for small free-swimming bacteria, leading to the following conclusions: 1) there are environmental conditions where(More)