Behavior of Free-Living and Plant-Parasitic Nematodes in a Thermal Gradient

Hitcho, Paul J.; Thorson, Ralph E.

doi:10.2307/3278213

Cited by 5 publications

(4 citation statements)

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“…Second, when starved, C. elegans disperses'from the'growth temperature rather than accumulates. In a previous study, C. elegans and several other nematodes were reported to migrate to lethal high temperatures in a liquid suspension thermotaxis assay (11,17). We have not seen this behavior in C. elegans, nor in' four other soil species we examined.…”

Section: Thermotaxis Of Normal Caenorhabditis Elegansmentioning

confidence: 99%

Normal and mutant thermotaxis in the nematode Caenorhabditis elegans.

Hedgecock¹,

Russell²

1975

Proc. Natl. Acad. Sci. U.S.A.

518

529

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When grown at a temperature from 16°to 250 and placed on a thermal gradient, the nematode Caenorhabditis elegans migrates to its growth temperature and then moves isothermally. Behavioral adaptation to a new temperature takes several hours. Starved animals, in contrast, disperse from the growth temperature. Several mutants selected for chemotaxis defects have thermotaxis defects as well; these behaviors depend on some common gene products. New mutants selected directly for thermotaxis defects have unusual phenotypes which suggest mechanisms for thermotaxis.Mutants with specific behavioral defects are useful in understanding the mechanisms by which genes direct the formation of a nervous system (1-4). Such mutants have been isolated in the small soil nematode Caenorhabditis elegans and, because the nervous system is simple (<300 cells), the mutant defects may be identified by serial section electron microscopy (1, 5-8). Mutants can also be analyzed by formal genetic techniques, such as dominance testing, complementation, and epistatic ordering, to gain insight into the structure of behavioral pathways and their development.Mutants of C. elegans with general behavioral defects (1, 9) and specific chemotaxis defects (5) have been described. This paper describes some mutants with specific defects in thermotaxis. These mutants are particularly interesting because thermotaxis can be modified by experience.MATERIALS AND METHODS Nematodes. Caenorhabditis elegans [var. Bristol (strain N2)] was used for behavioral studies and mutant selection. Worms were grown monoxenically in petri plates containing nematode growth minimal medium (NGMM) agar (5) preseeded with Escherichia coli strain OP50 (1).Temperature Gradients. A stable and reproducible linear temperature gradient was established by connecting two thermostatically regulated water baths, 50 and 350, by a 61 X 10 X 1.3 cm aluminum slab tightly bolted at each end to a 10-cm aluminum cube immersed in a bath. The temperatures of the baths were stable to 0.10. The room temperature varied from 19.50 to 20.50. Plastic petri plates (9-cm) confaining 35 ml of agar culture medium (NGMM) were placed on the aluminum gradient slab at regular intervals and the agar temperature was monitored with a glass probe thermistor. The agar surface established a uniform gradient of 0.5°/cm with an equilibration half-time of 5 min. The gradient was undistorted by edge-effects to within 1 cm of the petri plate wall. For graphical analysis, each plate was scored for three classes of nematodes: those migrating to the warmer half of the plate (H), those migrating to the colder half (C), and those never fully leaving the point of application (usually less than 10%). The results can be expressed by the percentage going to the warmer half 100 X H/(H + C) or by a "thermal preference" scale defined as 100 X (H -C)/(H + C) (Fig. 3). The second scale has the advantage that 0 indicates no preference, while positive and negative values indicate preferences for higher and lower temperatures, respect...

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Section: Thermotaxis Of Normal Caenorhabditis Elegansmentioning

confidence: 99%

Normal and mutant thermotaxis in the nematode Caenorhabditis elegans.

Hedgecock¹,

Russell²

1975

Proc. Natl. Acad. Sci. U.S.A.

518

529

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“…We did not assay thermotaxis with a time series or test thermotaxis at the extreme low end of the comfortable temperature range for this species [near 14°C for fecundity (Prasad et al, 2011)]. Similarly ectothermic, but parasitic, worms have been shown to navigate up thermal gradients to the point of death (McCue and Thorson, 1964;Hitcho and Thorson, 1972), and yet it seems similarly maladaptive for these C. briggsae strains to do the opposite and navigate down a gradient to the point at which they can no longer move. One possibility is that high temperatures impose a strong selective force in nature that has resulted in the evolution of a robust antithermophilic response.…”

Section: Tendency Toward Cryophilic Behaviourmentioning

confidence: 99%

Temperature-dependent behaviours are genetically variable in the nematode Caenorhabditis briggsae

Stegeman

Mesquita

Ryu

et al. 2012

Journal of Experimental Biology

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SUMMARY Temperature-dependent behaviours inCaenorhabditis elegans, such as thermotaxis and isothermal tracking, are complex behavioural responses that integrate sensation, foraging and learning, and have driven investigations to discover many essential genetic and neural pathways. The ease of manipulation of the Caenorhabditis model system also has encouraged its application to comparative analyses of phenotypic evolution, particularly contrasts of the classic model C. elegans with C. briggsae. And yet few studies have investigated natural genetic variation in behaviour in any nematode. Here we measure thermotaxis and isothermal tracking behaviour in genetically distinct strains of C. briggsae, further motivated by the latitudinal differentiation in C. briggsae that is associated with temperature-dependent fitness differences in this species. We demonstrate that C. briggsae performs thermotaxis and isothermal tracking largely similar to that of C. elegans, with a tendency to prefer its rearing temperature. Comparisons of these behaviours among strains reveal substantial heritable natural variation within each species that corresponds to three general patterns of behavioural response. However, intraspecific genetic differences in thermal behaviour often exceed interspecific differences. These patterns of temperature-dependent behaviour motivate further development of C. briggsae as a model system for dissecting the genetic underpinnings of complex behavioural traits. Supplementary material available online at

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“…This observation is consistent with all previous thermotaxis assays (1964). In the thermal gradients used in our study, L3 and L4 died at temperatures above 49-4°C, approximately 3°C higher than the detrimental temperatures found for the free-living nematodes Caenorhabditis elegans, Panagrellus redivivus, and plant-parasitic nematodes Aphelenchus avenae, Pratyienchus penetrans, Tylenchorhynchus claytoni (see HITCHO & THORSON, 1972). Migration into harmful temperatures may be a consequence of a deficiency in, or a complete lack of, a protective inhibitory response (CROLL, 1970).…”

Section: Discussionmentioning

confidence: 71%

“…Thermotaxis has been a widely documented behavioural response in nematodes, including animal-parasitic nematodes (KHALIL, 1922;RONALD, 1960;PARKER & HALEY, 1960;GUPTA, 1963;MCCUE & THORSON, 1964), plant-parasitic nematodes (CLAPHAM, 1931;WALLACE, 1961;EL-SHERIFF & MAI, 1969;HITCHO & THORSON, 1972) and free-living nematodes (HITCHO & THORSON, 1972;HEDGECOCK & RUSSELL, 1975). Previous literature on animal-parasitic nematodes reports positive thermotaxic responses but no negative thermotaxis, with the exception of Terranova decipiens, which exhibited both (RONALD, 1960).…”

Section: Introductionmentioning

confidence: 99%