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  • D B Dusenbery
  • 1997
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)
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)
Computer models for following stimulus gradients in two-dimensional space were evaluated to determine the relative advantages of different strategies and to identify the issues that must be addressed in making such a comparison. The simulations were implemented with emphasis on making them as general and free of specific assumptions as possible. Performance(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)
The behavior of crabs tracking odor in turbulent chemical plumes was compared to the performance of computer simulations of search behavior operating in similar chemical signal environments. The movement of blue crabs (Callinectes sapidus) towards a source of food odor was studied in controlled flow conditions in a flume. The evolving chemical stimulus(More)
Pheromones have demonstrated importance in mate location in many insect species. Because chemoreception is the most universal sense, it has been assumed that pheromones also are important in aquatic organisms, including bacteria, but few have been found. The physical limits on effective strategies for organisms to come into contact for mating were modeled(More)
The tethered-nematode technique was adapted for use with second-stage juveniles of Meloidogyne incognita. The data demonstrate that M. incognita exhibits the same patterns of behavior as adults of the free-living nematode, Caenorhabditis elegans. The principal differences are that M. incognita is slower and less regular in its behavior than C. elegans. The(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)