Shinya Matsumoto et al. (2003) International Worm Meeting "Effect of endocrine disrupters on reproduction of C. elegans."

Yasuki Matsumura, Tohomiko Mori, Shinya Matsumoto

[International Worm Meeting, 2003]

Certain chemical compounds in the environments are reported to mimic the functions of endocrine hormones of many organisms and because of their potential function to disrupt the hormone balance in organisms, they are often termed endocrine disrupters. Some phthalates used as plastic softeners (such as butylbenzylphthalate and dibutylphthalate), alkylphenols used in polymers (such as nonylphenol, p-octylphenol, Bisphenol A), synthetic sex hormones (such as diethylstilbestrol(DES) and ethynylestradiol) and heavy metal-containing compounds (such as tributyltin) are among those suspected to be endocrine disrupters. Among those which are reported to be the effect of endocrine disrupters, its influence on sperm formation and/or production in mammals has been attracting the attention. While the production of oocytes in C.elegans hermaphrodite continues throughout its adulthood, that of sperm takes place only during the L4 stage and the number of produced sperm is fairly constant (about 300 sperms), which means the number of the progeny of a self-mating hermaphrodite is limited by the number of the sperms produced. Therefore, the potential effect of endocrine disrupters on the sperm formation could be assessed by counting the number of progeny of a hermaphrodite. We investigated the effect of these compounds on the reproduction properties of C.elegans using this methods. Two mixture was prepared; DES, Bisphenol A, nonylphenol, octylphenol, dibutyl phthalate, butylbenzyl phthalate and styrene monomer as A group and B group for the mixture of heavy metals containing Cu, Ni, Co, Mn, Zn, Pb and Sn. These mixture were added separately or together at various concentration to NGM plate and the number of progeny from a hermaphrodite raised on it was counted. When worms were raised on the plate containing A group or B group or A+B group, significant decrease in the number of progeny was not observed at any concentration. On the other hand, when they are raised on a plate containing both group at very low concentration (1-10 ppt), the number of progeny appeared to decrease to 60-70 % of that of control. We are seeking which of the components in the mixture is responsible for the effect together.

Schwarz EM et al. (1996) East Coast Worm Meeting "Cellular and molecular analysis of thermosensation"

Chalfie M, Schwarz EM

[East Coast Worm Meeting, 1996]

While senses like sight, hearing, and mechanosensation are becoming well understood, thermosensation remains obscure. Work by Hedgecock (1) and Mori (2) has shown that C. elegans is a promising model system for metazoan thermosensation, but neither the cells nor the genes required for thermosensation in C. elegans are fully known. Previous work in this laboratory (3) has shown that at least three new deg mutations cause cells in the head to degenerate while partially crippling thermosensation; none of these are allelic to previously described ttx mutations . We have therefore begun to determine which cells are defective in these deg mutations. We have also begun genetic mapping experiments aimed at positional cloning of the wild-type deg loci. References: 1. Hedgecock, E.M. and Russell, R.L. (1975). Proc. Natl. Acad. Sci. U.S.A. 72, 4061-4065. 2. Mori, I. and Ohshima, Y. (1995). Nature 376, 344-348. 3. Treinin, M. and Chalfie, M. (1993). International C. elegans meeting abstracts, p. 446.

Ikeda, Shingo et al. (2011) International Worm Meeting "Integration of temperature signals in interneurons of C. elegans."

Kimata, Tsubasa, Ikeda, Shingo, Mori, Ikue

[International Worm Meeting, 2011]

Animals show complex behaviors as a consequence of integrating environmental information through neural circuits. In order to reveal the mechanism of integration, we are focusing on a neuronal circuit of C. elegans, composed of three interneurons, AIY, AIZ and RIA, which play an important role in thermotaxis behavior. The RIA neuron receives two upstream signals, one from AIY for thermophilic movement and the other from AIZ for cryophilic movement, and is supposed to integrate them to transmit to downstream motorneurons SMD and RMD, which connect with neck muscles directly (Mori and Ohshima, Nature, 1995; White et al., Phil. Trans. R. Soc. London, 1986). To understand how RIA integrates two opposite signals from AIY and AIZ, thus reflecting in the behavior, we tried to monitor the activity of AIY, AIZ and RIA with Ca2+ imaging using calcium sensor, GCaMP3 (Tian et al., Nat Methods, 2009). We so far observed significant responses of AIY and RIA to thermal stimuli, some of which were temperature-independent. The previous study using Cameleon showed that AIY responded significantly to thermal stimuli, while the response of RIA to thermal stimuli was minimal (Kuhara and Mori, J. Neurosci.,2006). Further, temperature-independent responses of AIY and RIA have not been reported, suggesting that GCaMP3 can detect different concentration range of intracellular Ca2+ compared to Cameleon YC2.12 or YC3.60. To further analyze how the circuit functions in integrating neural signals, we are currently trying to image the activity of AIZ and will perform simultaneous imaging of AIY, AIZ and RIA.

Paola Jurado et al. (2009) European Worm Neurobiology Meeting "Insights into the molecular mechanisms of Caenorhabditis elegans memory"

Paola Jurado, Ikue Mori

[European Worm Neurobiology Meeting, 2009]

Caenorhabditis elegans responds to a variety of environmental signals (volatile and water soluble chemicals, temperature, etc). The animals memorize these cues and are able to associate them with other existent conditions. Thermotaxis is a well characterized behavior in which C. elegans associates its cultivation temperature with food (Escherichia coli). This association drives the worms to seek their memorized temperature even in the absence of bacteria (1,2). This presents an ideal situation to investigate the molecular and cellular bases of sensory integration leading to complex processes such as memory and learning. We are trying to thoroughly investigate how the assimilation of thermo-sensory cues leads to memory, and how this thermal memory is modified over time. We have performed a screen to look for mutants with an abnormal memory or an altered decission making balance over thermal conditioning. We searched for animals conditioned to find E. coli at a certain temperature that take longer to leave it, in the absence of food, than wild type animals. These animals display a longer lasting memory or a slower decission making when thermal memory is confronted with hunger or the absence of food. One of the mutants isolated from this screening has been mapped to chromosome I and is currently under characterization. 1. I. Mori and Y. Ohshima (1995). "Neural regulation of thermotaxis in C. elegans." Nature 376(6538): 344-8. 2. I. Mori, H. Sasakura and A. Kuhara (2008). "Worm thermotaxis: a model system for analyzing thermosensation and neural plasticity." Curr Opin Neubiol. 2007 Dec 17(6):712-9.

Jurado, Paola et al. (2009) International Worm Meeting "Insights into the molecular mechanisms of Caenorhabditis elegans memory."

Jurado, Paola, Goto, Fuyuki, Mori, Ikue

[International Worm Meeting, 2009]

Caenorhabditis elegans responds to a variety of environmental signals (volatile and water soluble chemicals, temperature, etc). The animals memorize these cues and are able to associate them with other existent conditions. Thermotaxis is a well characterized behavior in which C. elegans associates its cultivation temperature with food (Escherichia coli). This association drives the worms to seek their memorized temperature even in the absence of bacteria (1,2). This presents an ideal situation to investigate the molecular and cellular bases of sensory integration leading to complex processes such as memory and learning. We are investigating how the assimilation of thermo-sensory cues leads to memory, and how this thermal memory is modified over time. We have performed two different screens to look for mutants with an abnormal memory or an altered decission making balance over thermal conditioning. On the first screen we searched for animals conditioned to find E. coli at a certain temperature that take longer to leave it, in the absence of food, than wild type animals. These animals display a longer lasting memory or a slower decission making when thermal memory is confronted with hunger or the absence of food. On the second screen we isolated several animals with a shorter memory or a faster decission making by selecting those that leave their memorized temperaure faster than the wild type animals. All these putative mutants are currently under characterization. 1. I. Mori and Y. Ohshima (1995). "Neural regulation of thermotaxis in C. elegans." Nature 376(6538): 344-8. 2. I. Mori, H. Sasakura and A. Kuhara (2008). "Worm thermotaxis: a model system for analyzing thermosensation and neural plasticity." Curr Opin Neubiol. 2007 Dec 17(6):712-9.

Paola Jurado et al. (2010) East Asia Worm Meeting "Insights into the molecular mechanisms of Caenorhabditis elegans memory"

Paola Jurado, Ikue Mori

[East Asia Worm Meeting, 2010]

Caenorhabditis elegans responds to a variety of environmental signals (volatile and water soluble chemicals, temperature, etc). The animals memorize these cues and are able to associate them with other existent conditions. Thermotaxis is a well characterized behavior in which C. elegans associates its cultivation temperature with food (Escherichia coli). This association drives the worms to seek their memorized temperature even in the absence of bacteria (1,2). This provides an ideal system to investigate the molecular and cellular bases of sensory integration, leading to complex processes such as memory and learning. We are investigating how the assimilation of thermo-sensory cues leads to the establishment of memory, and how this memory is affected by other cues and modified over time.We screened for mutants with an abnormal memory or an altered decision making balance over thermal conditioning. We found several putative mutants, in which once conditioned to find E. coli at a certain temperature, they take longer time to leave the temperature, in the absence of food, than wild type animals. Thus, these mutants display a longer lasting memory or a slower decision making phenotype when thermal memory is confronted with hunger or the absence of food. One of the mutants has been mapped to tag-210 that encodes a universally conserved GTPase in the OBG superfamily. The function of this protein in C. elegans is yet unknown although it is likely related to the regulation of translation.1. I. Mori and Y. Ohshima (1995). ""Neural regulation of thermotaxis in C. elegans."" Nature 376(6538): 344-8. 2. I. Mori, H. Sasakura and A. Kuhara (2008). ""Worm thermotaxis: a model system for analyzing thermosensation and neural plasticity."" Curr Opin Neubiol. 2007 Dec 17(6):712-9.

Lasse, S. et al. (2013) International Worm Meeting "Thermoreceptor neurons regulate the temperature-dependence of motor programs."

Wang, V. Y., Lasse, S., Goodman, M. B.

[International Worm Meeting, 2013]

In small ectotherms like C. elegans, temperature can influence behavioral performance directly or indirectly through signaling from specialized thermoreceptor neurons. Such temperature-dependence is also found in endotherms like mammals and birds. For instance, cooling decreases rhythmic movements associated with essential tremor and can also reduce pain and itch in humans. Essentially nothing is known in either ectotherms or endotherms about the potential role for thermoreceptor neurons in regulating the temperature-dependence of behavioral performance. We are working to fill this gap in understanding, focusing on two simple C. elegans behaviors: egg laying and locomotion. In wild-type N2 worms both behaviors display a similar dependence on temperature: rates increase with temperature and reach a maximum at 22-25 deg C then sharply decline above 26 deg C (egg laying) or 30 deg C (locomotion). If thermoreceptor neurons contribute to the temperature dependence of behavioral performance, then the rate-temperature (R-T) relationship should differ between wild-type worms and mutants with defects in thermosensation. Consistent with this idea, tax-4 mutants which lack the ability to respond to thermal gradients (Mori and Ohshima 1995) laid fewer eggs and crawled more slowly at 25-30 deg C. However, R-T curves had similar shapes in wild type and tax-4 worms. This suggests that egg laying and locomotion motor programs are intrinsically dependent on temperature, but input from the thermoreceptor neurons is required for wild type performance. This relationship may represent an evolutionary optimization of behavioral performance over a physiological range of temperatures. The neural circuits that regulate egg laying and locomotion do not overlap, indicating this as a general strategy that worms use to modulate behavioral performance. Mori I, Ohshima Y (1995) Neural regulation of thermotaxis in Caenorhabditis elegans. Nature 376:344 -348.

Atsushi Kuhara et al. (2004) East Asia Worm Meeting "TAX-6 calcineurin is required in RIA and AIZ interneurons for associative learning between temperature and starvation"

Atsushi Kuhara, Ikue Mori

[East Asia Worm Meeting, 2004]

Learning and memory are highly complex processes whose mechanisms are extremely intricate. In mammalian nervous system, the amount of information that is constantly received by the sensory neurons is processed and stored in complicated downstream neural circuits. We show here the simplest neural circuit regulating associative learning in C. elegans , where calcineurin, the Ca 2+ activated protein phosphatase, plays a critical role as a modulator of learning and memory. The calcineurin encoded by tax-6 gene is expressed in nearly all neurons including interneurons (Kuhara et. al., 2002), in which the learning and memory processes should occur. In order to investigate the function of TAX-6 calcineurin in the aspect of learning and memory, we made use of the interneuronal TAX-6 deficient transgenic mutants, tax-6;Ex[sensory+, inter-] , in which TAX-6 is expressed only in sensory neurons of tax-6 null mutants. We found that tax-6;Ex[sensory+, inter-] mutant animals showed defects in associative learning in two paradigms, (1) associative learning between temperature and starvation (Mohri et. al., 2003) and (2) associative learning between NaCl and starvation (Saeki et. al., 2001), although their capability of sensation and integration of two sensory inputs were normal. Defective associative learning between temperature and starvation of tax-6;Ex[sensory+, inter-] mutants were rescued by the expression of tax-6 cDNA in two pairs of interneurons, AIZ and RIA. We also found that in these neurons, TAX-6 calcineurin cell autonomously functions and its phosphatase activity is essential for associative learning. The AIZ-RIA mediated neural pathway is a critical wiring of thermotaxis neural circuit (Mori and Ohshima, 1995), suggesting that associative learning is regulated at neural circuit level. Thus, our results allow us to demonstrate the essential neural circuit regulating calcineurin-mediated associative learning in vivo. Kuhara et. al., 2002, Neuron 33, 751. Mohri et. al., 2003, IWM abstract. Saeki et. al., 2001, The Journal of Experimental Biology 204, 1757. Mori and Ohshima, 1995, Nature 376, 344.

Paola Jurado et al. (2008) European Worm Meeting "Insights into the molecular mechanisms of Caenorhabditis elegans memory"

Ikue Mori, Paola Jurado

[European Worm Meeting, 2008]

Caenorhabditis elegans responds to a variety of environmental signals. (volatile and water soluble chemicals, temperature, etc) being able to. memorize these cues and associate them with other existent conditions.. Thermotaxis is a well characterized behavior in which C. elegans associates. its cultivation temperature with food (Escherichia coli). This association. drives the worms to seek their memorized temperature even in the absence of. bacteria (1). The circuits underlying thermotaxis and several genes. implicated on its molecular mechanism have been identified (2,3). This. presents an ideal situation to investigate the molecular and cellular bases. of sensory integration leading to complex thoughts such as memory or. learning. We are interested in how the assimilation of thermo-sensory cues. leads to memory, and how this memory can be modified by the emergence of a. novel input which might cause a new behavioral pattern to arise.. We are examining the motor output towards several forms of memory/stimulus. choice paradigms that imply the juxtaposition of thermal memory versus a. new sensory cue such as hunger or a volatile odorant. We have performed a. screen looking for mutants with an unbalanced decision making over these. paradigms. We searched for animals that once have been conditioned to find. E. coli at a certain temperature, are unable to leave it even after an. unsuccessful search for food ignoring the hunger stimulus that should be. present.. We isolated several known and putative novel mutants that present the. desired altered behavior. These mutants are currently under. characterization.. 1. I. Mori and Y. Ohshima (1995). "Neural regulation of thermotaxis in C.. elegans." Nature 376(6538): 344-8. 2. I. Mori, H. Sasakura and A. Kuhara. (2008). "Worm thermotaxis: a model system for analyzing thermosensation and. neural plasticity." Curr Opin Neubiol (Epub ahead of press). 3. M. de Bono,. A. V. Maricq (2005). "Neuronal substrates of complex behaviors in C.. elegans." Annu Rev Neurosci 28(451):451-501.

Sylvia E J Fischer et al. (2002) European Worm Meeting "Characterization and identification of genes involved in transposon silencing."

Pawel Pasierbek, Nadine L Vastenhouw, Ronald H A Plasterk, Sylvia E J Fischer

[European Worm Meeting, 2002]

The transposon Tc1 is active in somatic cells of all C. elegans isolates. However, Tc1 activity in the germ line is restricted to certain strains: Tc1 is active in the germ line of Bergerac BO, but silenced in Bristol N2. Mori et al. showed that multiple genetic loci are involved in regulation of germ-line transposition (Mori et al., 1988). In an EMS screen for activation of Tc1 in the germ line of Bristol N2, 43 mutants were isolated that fall into two classes: mutants that are resistant to pos-1 RNAi, such as mut-7(pk204)(Ketting et al. 1999) and mut-14(pk738)(Tijsterman et al. 2002), and mutants that are wild type for pos-1 RNAi. The latter class consists of 20 mutants. These mutants are sensitive to RNAi directed against germline-expressed genes (pos-1, rba-2), as well as somatically-expressed genes (unc- 22). Furthermore, one of the mutants, mut-11 (pk724), was tested for gld-1 cosuppression, and found to be sensitive. Similarly, two previously isolated Tc1 mutators, mut-4(st700) and mut- 6(st702) are completely sensitive to both RNAi (Tabara et al., 1999; our data) and cosuppression (Ketting and Plasterk, 2000). RNAi-sensitive mutators do share some additional phenotypes with mut-7(pk204). Both RNAi- resistant and RNAi-sensitive mutators are thermo-sensitive sterile. DAPI-staining of the gonads several mutants shows a reduction of gonad size and the presence of univalents in diakinesis. Like mut-7, most RNAi-sensitive mutators show a high incidence of males. Classical genetic mapping of the Tc1-excision phenotype has placed the mut-13(pk766) mutation in the center of chromosome I. As an alternative approach to rapidly identify genes involved in transposon silencing in C. elegans, we are performing genome-wide screens using the RNAi feeding library to inactivate each C. elegans gene (in collaboration with Julie Ahringer, Cambridge, UK). We identified three putative mutator genes on chromosome I by scoring for Tc1 excision after feeding of unc- 22::Tc1 worms.