Rankin CH (1999) Worm Breeder's Gazette "Humidity affects the behavior of worms"

Rankin CH

[Worm Breeder's Gazette, 1999]

The take-home message from these observations is that the behavior of worms can be influenced by environmental variables not previously considered important. Consistency of conditions and controls for environmental effects are necessary in all behavioral studies. We routinely keep detailed records of time of day, temperature, and humidity for each worm that we test. Despite having a new environmental control system in the lab we now always pair an experimental and control worm and run them at as close to the same time and in same conditions as possible. The response that we study is backward movement in response to a mechanical tap to the NGM agar filled dish on which the worm sits. It is important to note that we do our testing with the lids off of the plates, so ambient environment can influence behavior. The temperature in my lab is relatively constant (range 19 to 21.5 degrees C) but prior to purchasing a new environmental control system the relative humidity ranged from ~35% to 75%. We found no consistent effect of time of day or of temperature on the magnitude of the reversal response, however we did find a significant effect of humidity. Higher humidity produced larger responses- especially when humidity exceeded 50%. For example, when humidity was 44% the mean response magnitude was 142.9 +/- SEM 22.16 pixels (on the monitor) - when the humidity was 56% the mean response magnitude was significantly larger at 199.5 +/- SEM 18.4 (t(15)= 1.84, p=.04). In another experiment a shift from 40% to 50% relative humidity led to a doubling of response magnitude. We hypothesize that changes in humidity affect the properties of the agar such that humidity above 50% makes worm movement easier, thus responses to tap are larger. Humidity also affects another aspect of worm behavior. We have been working for several years to show context conditioning with habituation (paper now submitted). This is associative learning in which worms learn the pairing of a chemical cue (NaCH3COO) with habituation training to tap - in later tests worms remember more of the training in the presence of the chemical cue than when there is no cue. This has been replicated 6 times (each with groups of at least 40 worms) when the relative humidity is below 50%, but has not, thus far been replicated when the humidity is over 50% (~4 tries). It may be that some aspect of either chemoreception or associative larning is also affected by changes in humidity.

Rankin CH et al. (2015) Elife "Finding a worm's internal compass."

Lin CH, Rankin CH

[Elife, 2015]

A pair of neurons is required for nematodes to be able to navigate using the Earth's magnetic field.

Rankin CH (2006) Curr Biol "Nematode behavior: the taste of success, the smell of danger!"

Rankin CH

[Curr Biol, 2006]

Through experience, the nematode worm Caenorhabditis elegans learns to distinguish high quality bacteria--food--from low quality or toxic bacteria. Increased release of the neurotransmitter serotonin onto identified interneurons determines whether C. elegans chooses to feed or leave.

Rankin CH (2000) Behav Neurosci "Context conditioning in habituation in the nematode Caenorhabditis elegans."

Rankin CH

[Behav Neurosci, 2000]

Habituation has traditionally been considered a nonassociative form of learning. However, recent research suggests that retention of this nonassociative form of learning may be aided by associations formed during training. An example of this is context conditioning, in which animals that are trained and tested in the presence of a contextual cue show greater retention than animals trained and tested in different environments. This article reports context conditioning in habituation in the nematode Caenorhabditis elegans. The results showed that retention of habituation to tap at both 10- and 60-s interstimulus intervals was significantly greater if training and testing occurred in the presence of the same chemosensory cue (NaCH3COO). This context conditioning showed both extinction and latent inhibition, demonstrating that these simple worms with only 302 neurons are capable of associative context conditioning.

Rankin CH (2005) Curr Biol "Nematode memory: now, where was I?"

Rankin CH

[Curr Biol, 2005]

The nematode Caenorhabditis elegans is able to use tastes, smells and temperature to locate food. New data show that worms can also detect the level of oxygen in the environment and migrate towards an oxygen level associated with food.

Rankin CH (2004) Curr Biol "Invertebrate learning: what can't a worm learn?"

Rankin CH

[Curr Biol, 2004]

The nematode worm Caenorhabditis elegans can learn and remember the stimuli it encounters, the environment it is in, and its own physiological state. Analyses of mutations in C. elegans that affect different aspects of experience are beginning to address the nature of learning.

Rankin CH et al. (1995) International C. elegans Meeting "BEHAVIORAL AND CELLULAR ANALYSES OF HABITUATION"

Rankin CH, Wicks SR

[International C. elegans Meeting, 1995]

Our previous circuit analyses have made it possible to investigate the roles of identified neurons in the mediation of behavioral plasticity. We have tested the roles of more than 35 different identified neurons and combinations of neurons (in more than 900 worms) in response to a mechanical tap to the dish and have shown that the tap withdrawal circuit consists of 3 head-touch cells (ALML, ALMR, and AVM), 2 tail-touch cells (PLML and PLMR), and 4 pairs interneurons (AVAs, AVBs, AVDs, PVCs), a single midline interneuron (DVA) and a pair of putative stretch receptors (PVDs). These neurons make up two competing circuits that are activated when a tap is delivered: the head touch circuit that produces reversals (swimming backwards), and the tail touch circuit that produces accelerations (swimming forwards). Each of the two circuits has an input to the final observed behaviour, and plays a role in the plasticity observed in habituation. Studies of each circuit independently (by ablating the opposing sensory cells) have shown that the head touch circuit habituates more quickly than the tail touch circuit, and the competition between the two circuits produces more rapid habituation than we would see with either circuit alone. No single neuron plays a major role in habituation, rather it appears that the decrements take place at varying rates over a number of synapses in the circuits.

Rankin BR et al. (2011) Biophys J "Nanoscopy in a living multicellular organism expressing GFP."

Schwarzer D, Nelson JC, Walter A, Hell SW, Schroeder J, Moneron G, Wurm CA, Colon-Ramos DA, Rankin BR

[Biophys J, 2011]

We report superresolution fluorescence microscopy in an intact living organism, namely Caenorhabditis elegans nematodes expressing green fluorescent protein (GFP)-fusion proteins. We also superresolve, by stimulated emission depletion (STED) microscopy, living cultured cells, demonstrating that STED microscopy with GFP can be widely applied. STED with GFP can be performed with both pulsed and continuous-wave lasers spanning a wide wavelength range from at least 556-592nm. Acquiring subdiffraction resolution images within seconds enables the recording of movies revealing structural dynamics. These results demonstrate that numerous microscopy studies of live samples employing GFP as the marker can be performed at subdiffraction resolution.

Rankin CH (1994) Seminars in The Neurosciences "Mechanistic questions raised by a behavioral analysis of habituation in Caenorhabditis elegans."

Rankin CH

[Seminars in The Neurosciences, 1994]

In the rush to discover molecular mechanisms of learning we sometimes lose sight of the behavior that we are trying to explain. Habituation is an example: although a 'simple' form of learning, surprisingly little is known about its underlying mechanisms. Although research on Aplysia has identified several possible mechanisms of habituation, there are still unanswered questions. Research on habituation in Caenorhabditis elegans demonstrates how a thorough understanding of the behavior can guide studies of mechanism. In particular, interstimulus interval (ISI) is a key component in determining the dynamics of habituation; no mechanistic explanation is complete without accounting for the effects of different ISIs.

Catharine Rankin et al. (2003) International Worm Meeting "The effects of avr-14 on short- and long-term memory."

Nicholas Dube, Stephan Steidl, Catharine Rankin

[International Worm Meeting, 2003]

avr-14 encodes an -type subunit of a glutamate-gated chloride channel (GluCls) in Caenorhabditis elegans. avr-14 is expressed on the glutamatergic mechanosensory neurons of the tap-withdrawal response that synapse onto the command interneurons of the circuit. Because avr-14 is expressed on the touch cells it was hypothesized that it might play a role in experience-dependant plasticity in the response to tap. Worms with a mutation in avr-14 were tested for short-term and long-term habituation of the tap response. The mutation selectively affects short-term habituation for shorter interstimulus intervals (ISIs; 10s and 30s) while not affecting habituation for long ISIs (45s and 60s). These results provide support for the hypothesis that in C. elegans there are multiple ISI-dependant short-term memory systems. avr-14 worms show long-term memory for habituation training comparable to wild-type controls when given distributed training and testing with a 60s ISI. avr-14 worms, unlike wild-type controls, also show long-term memory when trained and tested with a 10s ISI. Furthermore, long-term memory for this training protocol is protein synthesis dependant, as administering heat shock in between blocks of training blocks the formation of long-term memory. This suggests that in wild-type worms the presence of avr-14 blocks the conversion from short-term to long-term memory following training with short ISIs.Thanks to Joe Dent for avr-14.