Thermosensory Behaviour in Paramecium tetraurelia: a Quantitative Assay and Some Factors that Influence Thermal Avoidance

Hennessey, Todd M.; Nelson, David Lee

doi:10.1099/00221287-112-2-337

Cited by 32 publications

(14 citation statements)

References 34 publications

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“…Ciliated protozoa alter their membrane lipid compositions, depending on the growth temperature (Kasai et al, 1976;Hennessey & Nelson, 1979). It is likely that this change is adaptive and affects the electric properties of the membrane.…”

Section: Discussionmentioning

confidence: 99%

“…Wild-type paramecia grown at room temperature avoid a zone of higher temperature (e.g., 35 ~ teaB can pass through this zone efficiently (T. Hennessey, personal communication) and so can wild type previously grown at 35 ~ (Hennessey & Nelson, 1979). Because the wild type grown at the elevated temperatures phenocopies of the teaB mutant thermotactically, it should be of interest to examine the various bioelectric properties of the membrane of such a wild type to see whether they are similar to those of teaB grown at room temperature.…”

Section: The Effects Of Growth Temperaturesmentioning

confidence: 99%

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Possible reduction of surface charge by a mutation inParamecium tetraurelia

Satow

Kung

1981

J. Membrain Biol.

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Under voltage clamp, a mutant of Paramecium tetraurelia (teaB) shows a shift in the positive direction of the voltage sensitivity of the Ca conductance and the depolarization inactivation curve by 10 mV with no change in the total conductance. This effect can be mimicked in the wild type by the addition of external CA2+ or Mg2+. The mutation also shifts the resting potential and the voltage sensitivities of the delayed rectification (depolarization-sensitive) K conductance and the anomalous rectification (hyperpolarization-sensitive) K conductance in the positive direction to a similar extent. This systematic shift of channel voltage sensitivities is best explained by the reduction of the surface negative charges of the membrane due to the mutation.

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Section: Discussionmentioning

confidence: 99%

Section: The Effects Of Growth Temperaturesmentioning

confidence: 99%

Possible reduction of surface charge by a mutation inParamecium tetraurelia

Satow

Kung

1981

J. Membrain Biol.

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“…In models 1 and 2, it is probable that growth temperature affects warm avoidance through neuronal plasticity. However, it could be possible that some metabolic or physiological state, such as fatty acid composition (Tanaka et al, 1996), depending on the culture temperature is the 'memory' of the temperature instead of neural memory since similar thermal avoidance is also observed in organisms that do not have a nervous system (Hennessey and Nelson, 1979;Whitaker and Poff, 1980). In model 1, a single neuronal pathway for thermosensation is required, whereas two pathways are postulated in models 2 and 3.…”

Section: Models For Thermal Responsesmentioning

confidence: 99%

Distribution and movement ofCaenorhabditis eleganson a thermal gradient

Yamada

Ohshima

2003

Journal of Experimental Biology

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Behavior of Caenorhabditis elegans on a thermal gradient has been studied as one of several plastic responses of the organism to environmental signals. C. elegans is suitable for studying neuronal mechanisms underlying behavioral control, since it has a compact nervous system whose connectivity has been mapped almost completely (White et al., 1986) and it moves in a relatively simple way of forward and backward movements with spontaneous turns (Croll, 1975).It was previously reported that C. elegans migrates towards a feeding temperature and stays there by moving isothermally (Hedgecock and Russell, 1975). Balancing of opposing neural pathways that drive worms up or down the temperature gradient was proposed to regulate such movement (Hedgecock and Russell, 1975;Mori and Ohshima, 1995), and genes or neurons involved in the pathways have been studied (for reviews, see Bargmann and Mori, 1997;Mori and Ohshima, 1997). When starved, worms are said to disperse from that temperature (Hedgecock and Russell, 1975). These results led to an intriguing hypothesis that worms memorize a culture temperature in association with food condition and regulate their behavior in reference to the memorized temperature. However, as described below, such understanding of C. elegans behavior is not always based on very reliable results, and therefore the basic concept of so-called 'thermotaxis' and the resulting neural model are disputable.Previous studies on the thermal behavior (or thermotaxis) of C. elegans were mainly performed either by observing tracks of one or a few worms on a 9·cm agar plate carrying a radial temperature gradient or by measuring the distribution of a worm population on a linear temperature gradient (Hedgecock and Russell, 1975;Mori and Ohshima, 1995;Komatsu et al., 1996;Hobert et al., 1997;Cassata et al., 2000a). We noticed several problems in both types of assay. First, 'isothermal movement' of a worm indicated by a circular track on a radial gradient occurs, on average, only in a small fraction of an assay period, although good examples have been provided. Worms more often migrate in other temperature regions, but such behavior has not been analysed thoroughly and understanding of the whole behavior is lacking. Second, the radial temperature gradient changes over time, even during a 1·h assay period, and is quite sensitive to room temperature. Therefore, even with a good thermal sensor, precise estimation of the actual temperature of an isothermal track at the time it is drawn is difficult. This means that although an isothermal track was assumed to provide good evidence for memory of the growth temperature, the relationship between the actual temperature at which it is drawn and growth To analyze thermal responses of Caenorhabditis elegans in detail, distribution of a worm population and movement of individual worms were examined on a linear, reproducible and broad temperature gradient. Assay methods were improved compared with those reported previously to ensure good motility and dispersion of worms. Well-f...

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“…In unicellular organisms, it is known that the ciliated protozoa, Paramecium, has both warm and cold receptors (2,5,9). Intracellular recordings from Parameciumhave shownthat either warmor cold stimuli induce membrane depolarization (3,13).…”

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Cold-sensitive responses in the Paramecium membrane.

Inoue

Nakaoka

1990

Cell Struct. Funct.

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ABSTRACT. A transient depolarization was recorded in response to the cooling of a deciliated Paramecium. The amplitude of the depolarization was almost proportional to the cooling rate. Therefore, the cells are sensitive to the rate of temperature change. The input resistance of the membrane transiently increased during the cooling. Whenconstant current was applied to shift the resting membranepotential to a negative or positive level, the initial depolarization in response to cooling decreased, and the following hyperpolarization during cooling reversed to a gradual depolarization during a positive shift. The potential at which the reversal occurred was independent of K+ concentration and was slightly dependent on Ca2+ concentration (10 mV/log[Ca2+]o). The amplitude of the initial depolarization decreased with the increase in K+ and was not affected by Ca2+. These results are discussed in terms of changes in membraneconductances in response to cooling.In multicellular organisms, there are specialized thermosensory receptors (4), which are further specified as warm-and cold-receptors. In unicellular organisms, it is known that the ciliated protozoa, Paramecium, has both warm and cold receptors (2, 5, 9). Intracellular recordings from Parameciumhave shownthat either warmor cold stimuli induce membrane depolarization (3,13). The study of cell fragments revealed that the cold receptors are localized at the anterior of the cell, while warm receptors are distributed throughout the rest of the cell (8). The depolarization in response to warmingis induced by an increase in membraneconductance for Ca2+ and the depolarization in response to cooling is induced by a decrease in the conductance for K+ (8).Somebasic properties of the cell during depolarization prompted by thermal stimuli are uncertain, e.g. whether the cells detect thermal stimuli as a successive change of temperature or as a rate of temperature change, and whether the membrane resistance of the whole cell transiently decreases or increases during the depolarization. In order to investigate these properties, we used a deciliated cell to take measurements in the absence of an action potential (1, ll) and recorded the potential response upon cooling. MATERIALS AND METHODS Cells. Paramecium multimicronucleatum was cultured inTo whomcorrespondence should be sent.a hay infusion inoculated with Klebsiella pneumoniae. The culture temperature was kept constant at 25°C by incubation in a water bath. Parameciumcells at the stationary phase were collected by low-speed centrifugation and suspended in a solution containing 0.25 mMCaCl2, 0.5 mMMgCl2, 2 mMKC1 and 2mMTris-HCl (pH7.2). This solution was used as a standard solution in all experiments. For experiments investigating ionic dependence, the potassium or calcium concentrations of the standard solution were varied. Deciliation. The cells were deciliated by incubation in a standard solution containing 5% ethanol for about 2 min and then returned to the standard solution whosetemperature was kept at 25°C (10).Intracel...

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Thermosensory Behaviour in Paramecium tetraurelia: a Quantitative Assay and Some Factors that Influence Thermal Avoidance

Cited by 32 publications

References 34 publications

Possible reduction of surface charge by a mutation inParamecium tetraurelia

Possible reduction of surface charge by a mutation inParamecium tetraurelia

Distribution and movement ofCaenorhabditis eleganson a thermal gradient

Cold-sensitive responses in the Paramecium membrane.

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