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Author (up) Adachi, R.; Osada, H.; Shingai, R. file  url
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  Title Phase-dependent preference of thermosensation and chemosensation during simultaneous presentation assay in Caenorhabditis elegans Type Journal Article
  Year 2008 Publication BMC Neuroscience Abbreviated Journal BMC Neurosci  
  Volume 9 Issue Pages 106  
  Keywords Animals; Caenorhabditis elegans; Chemotactic Factors; Chemotaxis--physiology; Choice Behavior; Cold Temperature; Pentanols; Psychomotor Performance--physiology; Sensation; Sensory Receptor Cells--physiology; Sodium Chloride; Thermosensing--physiology  
  Abstract BACKGROUND: Multi-sensory integration is necessary for organisms to discriminate different environmental stimuli and thus determine behavior. Caenorhabditis elegans has 12 pairs of amphid sensory neurons, which are involved in generating behaviors such as thermotaxis toward cultivation temperature, and chemotaxis toward chemical stimuli. This arrangement of known sensory neurons and measurable behavioral output makes C. elegans suitable for addressing questions of multi-sensory integration in the nervous system. Previous studies have suggested that C. elegans can process different chemoattractants simultaneously. However, little is known about how these organisms can integrate information from stimuli of different modality, such as thermal and chemical stimuli. RESULTS: We studied the behavior of a population of C. elegans during simultaneous presentation of thermal and chemical stimuli. First, we examined thermotaxis within the radial temperature gradient produced by a feedback-controlled thermoregulator. Separately, we examined chemotaxis toward sodium chloride or isoamyl alcohol. Then, assays for simultaneous presentations of 15 degrees C (colder temperature than 20 degrees C room temperature) and chemoattractant were performed with 15 degrees C-cultivated wild-type worms. Unlike the sum of behavioral indices for each separate behavior, simultaneous presentation resulted in a biased migration to cold regions in the first 10 min of the assay, and sodium chloride-regions in the last 40 min. However, when sodium chloride was replaced with isoamyl alcohol in the simultaneous presentation, the behavioral index was very similar to the sum of separate single presentation indices. We then recorded tracks of single worms and analyzed their behavior. For behavior toward sodium chloride, frequencies of forward and backward movements in simultaneous presentation were significantly different from those in single presentation. Also, migration toward 15 degrees C in simultaneous presentation was faster than that in 15 degrees C-single presentation. CONCLUSION: We conclude that worms preferred temperature to chemoattractant at first, but preferred the chemoattractant sodium chloride thereafter. This preference was not seen for isoamyl alcohol presentation. We attribute this phase-dependent preference to the result of integration of thermosensory and chemosensory signals received by distinct sensory neurons.  
  Call Number Serial 262  
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Author (up) Adachi, R.; Wakabayashi, T.; Oda, N.; Shingai, R. file  url
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  Title Modulation of Caenorhabditis elegans chemotaxis by cultivation and assay temperatures Type Journal Article
  Year 2008 Publication Neuroscience Research Abbreviated Journal Neurosci Res  
  Volume 60 Issue 3 Pages 300-306  
  Keywords Ammonium Chloride; Animals; Behavior, Animal/*physiology; Caenorhabditis elegans/*physiology; Chemoreceptor Cells/physiology; Chemotaxis/*physiology; Neurons, Afferent/*physiology; Sodium Acetate; Stimulation, Chemical; *Temperature  
  Abstract The chemotaxis behaviors of the nematode Caenorhabditis elegans cultivated at various temperatures (15 degrees C, 20 degrees C and 25 degrees C) were examined at various temperatures (10 degrees C, 15 degrees C, 20 degrees C and 25 degrees C) to determine the multi-sensory integration of physical (thermal) and chemical sensory information within its nervous system. Chemotaxis behavior toward sodium acetate and ammonium chloride were differently affected by both assay and cultivation temperatures, suggesting that the temperature effect on chemotaxis is not general, but rather distinctive for each chemosensory pathway. Since thermosensory cues are likely encountered constantly in C. elegans, we supposed that the chemotaxis behaviors of worms are achieved by the integration of chemo- and thermosensory information. To verify the possible contribution of thermosensory function in chemotaxis, we examined the chemotaxis behaviors of ttx-1(p767) mutant worms with defective AFD thermosensory neurons. The chemotaxis behaviors toward sodium acetate or ammonium chloride of mutant worms cultivated at 20 degrees C and 25 degrees C were reduced relative to those of wild-type worms. These results indicate the important role of multi-sensory integration of chemosensory and thermosensory information in chemotaxis behavior of the C. elegans.  
  Call Number Serial 1025  
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Author (up) Anderson, J.L.; Albergotti, L.; Ellebracht, B.; Huey, R.B.; Phillips, P.C. file  url
openurl 
  Title Does thermoregulatory behavior maximize reproductive fitness of natural isolates of Caenorhabditis elegans? Type Journal Article
  Year 2011 Publication BMC Evolutionary Biology Abbreviated Journal BMC Evol Biol  
  Volume 11 Issue Pages 157  
  Keywords Acclimatization; Animals; Body Temperature Regulation; Caenorhabditis elegans--genetics, physiology; Genetic Fitness; Temperature  
  Abstract BACKGROUND: A central premise of physiological ecology is that an animal's preferred body temperature should correspond closely with the temperature maximizing performance and Darwinian fitness. Testing this co-adaptational hypothesis has been problematic for several reasons. First, reproductive fitness is the appropriate measure, but is difficult to measure in most animals. Second, no single fitness measure applies to all demographic situations, complicating interpretations. Here we test the co-adaptation hypothesis by studying an organism (Caenorhabditis elegans) in which both fitness and thermal preference can be reliably measured. RESULTS: We find that natural isolates of C. elegans display a range of mean thermal preferences and also vary in their thermal sensitivities for fitness. Hot-seeking isolates CB4854 and CB4857 prefer temperatures that favor population growth rate (r), whereas the cold-seeking isolate CB4856 prefers temperatures that favor Lifetime Reproductive Success (LRS). CONCLUSIONS: Correlations between fitness and thermal preference in natural isolates of C. elegans are driven primarily by isolate-specific differences in thermal preference. If these differences are the result of natural selection, then this suggests that the appropriate measure of fitness for use in evolutionary ecology studies might differ even within species, depending on the unique ecological and evolutionary history of each population.  
  Call Number Serial 261  
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Author (up) Anderson, J.L.; Albergotti, L.; Proulx, S.; Peden, C.; Huey, R.B.; Phillips, P.C. file  url
openurl 
  Title Thermal preference of Caenorhabditis elegans: a null model and empirical tests Type Journal Article
  Year 2007 Publication The Journal of Experimental Biology Abbreviated Journal J Exp Biol  
  Volume 210 Issue Pt 17 Pages 3107-3116  
  Keywords Acclimatization; Animals; Behavior, Animal; Body Temperature Regulation; Caenorhabditis elegans--physiology; Escherichia coli--growth & development; Models, Biological; Temperature  
  Abstract The preferred body temperature of ectotherms is typically inferred from the observed distribution of body temperatures in a laboratory thermal gradient. For very small organisms, however, that observed distribution might misrepresent true thermal preferences. Tiny ectotherms have limited thermal inertia, and so their body temperature and speed of movement will vary with their position along the gradient. In order to separate the direct effects of body temperature on movement from actual preference behaviour on a thermal gradient, we generate a null model (i.e. of non-thermoregulating individuals) of the spatial distribution of ectotherms on a thermal gradient and test the model using parameter values estimated from the movement of nematodes (Caenorhabditis elegans) at fixed temperatures and on a thermal gradient. We show that the standard lab strain N2, which is widely used in thermal gradient studies, avoids high temperature but otherwise does not exhibit a clear thermal preference, whereas the Hawaiian natural isolate CB4856 shows a clear preference for cool temperatures ( approximately 17 degrees C). These differences are not influenced substantially by changes in the starting position of worms in the gradient, the natal temperature of individuals or the presence and physiological state of bacterial food. These results demonstrate the value of an explicit null model of thermal effects and highlight problems in the standard model of C. elegans thermotaxis, showing the value of using natural isolates for tests of complex natural behaviours.  
  Call Number Serial 260  
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Author (up) Ardiel, E.L.; Rankin, C.H. file  url
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  Title C. elegans: social interactions in a “nonsocial” animal Type Journal Article
  Year 2009 Publication Advances in Genetics Abbreviated Journal Adv Genet  
  Volume 68 Issue Pages 1-22  
  Keywords Animals; Behavior, Animal; Caenorhabditis elegans/genetics/*physiology; Caenorhabditis elegans Proteins/genetics; Ecosystem; Female; Genetics, Behavioral; Male; Pheromones/physiology; Social Behavior  
  Abstract As self-fertilizing nematodes, Caenorhabditis elegans do not normally come to mind when one thinks of social animals. However, their reproductive mode is optimized for rapid population growth, and although they do not form structured societies, conspecifics are an important source of sensory input. A pheromone signal underlies multiple complex behaviors, including diapause, male-mating, and aggregation. The use of C. elegans in sociogenetics research allows for the analysis of social interactions at the level of genes, circuits, and behaviors. This chapter describes natural polymorphisms in mab-23, plg-1, npr-1, and glb-5 as they relate to two C. elegans social behaviors: male-mating and aggregation.  
  Call Number Serial 1074  
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