THE PHOTOMOVEMENT OF Caenorhabditis elegans, A NEMATODE WHICH LACKS OCELLI. PROOF THAT THE RESPONSE IS TO LIGHT NOT RADIANT HEATING

Burr, Aaron

doi:10.1111/j.1751-1097.1985.tb03529.x

Cited by 39 publications

(26 citation statements)

References 31 publications

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“…We chose a laser diode that emits at a wavelength close to IR light (685 Ϯ 0.5 nm). It has been reported previously that C. elegans reacts only weakly to light (23). Most notably, when exposed to monochromatic light ranging from 420 to 680 nm, wavelengths outside of 520-600 nm elicited no response (23).…”

Section: Resultsmentioning

confidence: 81%

“…It has been reported previously that C. elegans reacts only weakly to light (23). Most notably, when exposed to monochromatic light ranging from 420 to 680 nm, wavelengths outside of 520-600 nm elicited no response (23). Because our laser diode does not emit below 680 nm, we ensured that the avoidance reaction we analyzed was caused by the response to heat rather than by photons.…”

Section: Resultsmentioning

confidence: 99%

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Thermal avoidance in Caenorhabditis elegans : An approach to the study of nociception

Wittenburg

Baumeister²

1999

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

177

189

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Upon perception of a noxious stimulus, an organism executes defense mechanisms, such as escape responses. The molecular basis of these mechanisms is poorly understood. In this paper we show that upon exposure to noxious temperature, Caenorhabditis elegans reacts by a withdrawal reflex. To analyze this thermal avoidance behavior, we developed a laser-based assay to quantify the response. The escape reflex can be observed in 98% of the adult animals, but is not executed in animals in diapause. The thermal avoidance response differs significantly from the thermotaxis behavior that is based on the perception of physiological temperature. It involves different neurons and is influenced by mutations in distinct genes. As in mammals, the strength of the thermal avoidance response is increased by application of capsaicin, the pungent ingredient in chili peppers. We find that thermal avoidance is strongly reduced in mutants affecting the neural transmission modulated by glutamate and neuropeptides as well as in mutants affecting the structure and function of sensory neurons. We suggest that the study of this nociceptive behavior in C. elegans can be used to understand the genetic and molecular basis of thermal nociception.Every organism depends on a set of regulatory, protective behaviors to ensure survival. Upon exposure to a noxious mechanical, chemical, or thermal stimulus, animals execute a protective withdrawal-reflex program to prevent cellular damage. In the central nervous system, aversive and protective reactions to these stimuli include the sensation of pain. Whereas the perception of pain may be silenced during anesthesia, nociceptive reflexes by the peripheral nervous system are still executed (1).In vertebrates, the presence of tissue-damaging stimuli or the existence of tissue damage are sensed by primary afferent neurons. These, in general, respond only to high intensities of a stimulus and correspond either to a single sensory modality or are polymodal (are stimulated, for example, by mechanical or thermal stimuli). Several animal and in vitro models have been established to study the physiological and pharmacological parameters that interfere with pain perception and nociception. Recently, cell culture experiments suggested that the vanilloid receptor VR1 is activated both by capsaicin and by noxious heat (2, 3). VR1 belongs to the evolutionary conserved TRP (transient receptor potential) family of nonselective ion channels and is located in sensory nerve endings of the dorsal root ganglion. Despite this finding, little is known about the molecular mechanisms of nociception.The nematode Caenorhabditis elegans is an excellent organism in which to study the behavioral responses to noxious environmental stimuli. Its powerful genetics and the simple nervous system have greatly facilitated the identification of the neural circuits and genes involved in various avoidance reactions such as its response to noxious chemicals, high osmolarities, acidic pH (4), and noxious mechanical stimuli (5).We show her...

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Section: Resultsmentioning

confidence: 81%

Section: Resultsmentioning

confidence: 99%

Thermal avoidance in Caenorhabditis elegans : An approach to the study of nociception

Wittenburg

Baumeister²

1999

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

177

189

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“…Although C. elegans displays light sensing behaviors (Burr, 1985), it lacks morphologically defined eyes. Because a key transcription factor in the eye specification program is highly conserved among all animals -eyeless in Drosophila, Pax6 in vertebrates and vab-3 in C. elegans (Carroll et al, 2001;Davidson, 2001) -we also tested enhancers of Drosophila eyespecific genes in C. elegans.…”

Section: Resultsmentioning

confidence: 99%

Functional tests of enhancer conservation between distantly related species

Ruvinsky

Ruvkun

2003

Development

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Expression patterns of orthologous genes are often conserved, even between distantly related organisms, suggesting that once established, developmental programs can be stably maintained over long periods of evolutionary time. Because many orthologous transcription factors are also functionally conserved, one possible model to account for homologous gene expression patterns, is conservation of specific binding sites within cis-regulatory elements of orthologous genes. If this model is correct, a cis-regulatory element from one organism would be expected to function in a distantly related organism. To test this hypothesis, we fused the green fluorescent protein gene to neuronal and muscular enhancer elements from a variety of Drosophila melanogaster genes, and tested whether these would activate expression in the homologous cell types in Caenorhabditis elegans. Regulatory elements from several genes directed appropriate expression in homologous tissue types, suggesting conservation of regulatory sites. However, enhancers of most Drosophila genes tested were not properly recognized in C. elegans, implying that over this evolutionary distance enough changes occurred in cis-regulatory sequences and/or transcription factors to prevent proper recognition of heterospecific enhancers. Comparisons of enhancer elements of orthologous genes between C. elegans and C. briggsae revealed extensive conservation, as well as specific instances of functional divergence. Our results indicate that functional changes in cis-regulatory sequences accumulate on timescales much shorter than the divergence of arthropods and nematodes, and that mechanisms other than conservation of individual binding sites within enhancer elements are responsible for the conservation of expression patterns of homologous genes between distantly related species.

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“…These cells receive synaptic input from AFD sensory cells, which are thermosensitive and possibly photosensitive (Ware et al, 1975;Burr, 1985). Therefore, the AIY interneuron/AFD sensory neuron circuit in nematodes may be analogous to the bipolar interneuron/photoreceptor sensory neuron interaction in vertebrate retinae.…”

mentioning

confidence: 97%

Vsx-1 andVsx-2: Differential expression of twoPaired-like homeobox genes during zebrafish and goldfish retinogenesis

et al. 1997

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Vsx-1 and Vsx-2 are two homeobox genes that were cloned originally from an adult goldfish retinal library. They are members of the paired-like:CVC gene family, which is characterized by the presence of a paired homeodomain and an additional conserved region, termed the CVC domain. To analyze the possible roles for Vsx-1 and Vsx-2 in eye development, we used in situ hybridization to examine their expression patterns in zebrafish and goldfish embryos. Vsx-2 is initially expressed by proliferating neuroepithelial cells of the presumptive neural retina, then it is down-regulated as differentiation begins, and it is finally reexpressed at later stages of differentiation in a subset of cells, presumed to be bipolar cells, in the inner nuclear layer. In contrast, Vsx-1 is expressed only weakly in undifferentiated, presumptive neural retina and is then up-regulated selectively in presumptive bipolar cells at early stages of differentiation (when Vsx-2 is turned off), before decreasing to an intermediate level, which is maintained in the differentiated (adult) retina. The restricted expression patterns of Vsx-2 correspond to the observed phenotypes in mice with the ocular retardation mutation (orJ), further supporting the notion that Vsx-2 and Chx10 are homologues. The sequential complimentary and then corresponding expression patterns of Vsx-1 and Vsx-2 suggest that these similar transcription factors may be recruited for partially overlapping, but distinct, functions during the development of the retina.

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THE PHOTOMOVEMENT OF Caenorhabditis elegans, A NEMATODE WHICH LACKS OCELLI. PROOF THAT THE RESPONSE IS TO LIGHT NOT RADIANT HEATING

Cited by 39 publications

References 31 publications

Thermal avoidance in Caenorhabditis elegans : An approach to the study of nociception

Thermal avoidance in Caenorhabditis elegans : An approach to the study of nociception

Functional tests of enhancer conservation between distantly related species

Vsx-1 andVsx-2: Differential expression of twoPaired-like homeobox genes during zebrafish and goldfish retinogenesis

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