Koga M et al. (1994) Worm Breeder's Gazette "Drosophila MAP kinase kinase (MAPKK) Suppressed let-23 Vulvaless Phenotype and Induced a Normal Vulva"

Koga M, Ohshima YM

[Worm Breeder's Gazette, 1994]

Drosophila MAP kinase kinase (MAPKK) suppressed let-23 vulvaless phenotype and induced a normal vulva. Makoto Koga and Yasumi Ohshima Department of Biology, Faculty of Science, Kyushu University, Hakozaki, Fukuoka 812, Japan

Fujii, Satoko et al. (2017) International Worm Meeting "Neuronal circuit underlying cultivation temperature-dependent cold acclimation."

Kuhara, Atsushi, Ioroi, Makoto, Ohta, Akane, Fujii, Satoko

[International Worm Meeting, 2017]

Temperature acclimation is important for survival and proliferation of animals. The nematode C. elegans can survive at 2 deg C after cultivation at 15 deg C, however, the animals cultivated at 25 deg C cannot survive at 2 deg C. Interestingly, 25 deg C-cultivated animals are then exposed to 15 deg C for 3 hours and it comes to survive at 2 deg C. Thus, the tolerance against 2 deg C can be plastically changed depending on cultivation temperature. We defined this phenomenon as cold acclimation. Our previous genetical and physiological analysis using calcium imaging showed that temperature is received by ASJ sensoryneuron, which controls cold acclimation. Here we found that ASJ itself without synaptic input alters temperature response depending on cultivation temperature. In mammals, cAMP responsible element binding protein (CREB), a transcription factor, is involved in learning and memory. In C. elegans, crh-1 mutant lacking CREB showed abnormal temperature response of ASJ sensoryneuron, which was rescued by the expression of crh-1 cDNA in ASJ. crh-1 mutant also showed abnormal delayed-phenotype in cold acclimation. To identify the specific cells required for CREB-dependent cold acclimation, we expressed crh-1cDNA in various sets of neurons in crh-1 mutant. We found that delayed-cold acclimation of crh-1 mutant was rescued by the simultaneous expression of crh-1cDNA in ASJ and RMG neurons. However, there is no direct physical connection between these two neurons such as GAP junctions and synaptic connections. We are exploring the neuronal circuits from ASJ to RMG in cold acclimation. We analyzed cold acclimation of the mutants defective in neuropeptide and serotonin signaling, because RMG expresses NPR-1, a neuropeptide receptor, and HSN neuron upstream of RMG is a serotonergic neuron. We analyzed cold acclimation speed of the mutants defective in npr-1, tph-1 or mod-1. TPH-1 is serotonin synthase expressed in HSN, and MOD-1 is serotonin receptor in RMG. npr-1, tph-1 and mod-1 mutants however showed normal cold acclimation, suggesting that serotonin and NPR-1 are not involved in neural signaling from ASJ to RMG in cold acclimation. We are going on the analysis whether other neurotransmitter receptors in RMG, such as glutamate receptor, are required for cold acclimation.

Ohta, Akane et al. (2015) International Worm Meeting "CREB facilitates a replacement of temperature experience-linked cold tolerance."

Ohta, Akane, Kuhara, Atsushi, Ioroi, Makoto, Takagaki, Natsune

[International Worm Meeting, 2015]

Environmental situation can be changed continuously, therefore animals adapt to environment such as high or cold temperature, humidity and smell. One of environment adaptabilities is cold tolerance. C. elegans stores temperature experiences and can induce temperature memory-linked cold tolerance, which is a phenomenon that 15degC -cultivated animals can survive at 2iotadegC, however, 20degC- or 25degC-cultivated animals can not survive after cold shock. We have recently reported that one pair of sensory neuron ASJ, which is known as a pheromone and light-sensing neuron, causes cold tolerance by sensing temperature (1). Temperature signals from ASJ are transmitted to downstream neurons of ASJ and intestine through insulin (1).We show here that cAMP response element binding protein (CREB) is required for building a new memory of the cold tolerance. Almost wild-type animals lost cold tolerance within three hours after temperature shift from 15 to 25 degree. However, a half of crh-1/CREB mutants kept cold tolerant even three hours after temperature shift from 15degC to 25degC. This abnormality of crh-1 mutant was rescued by the expression of CREB in neurons. We are going to determine a set of neurons, in which CREB contributes to make memory for cold tolerance.Our recent Ca2+-imaging analysis for monitoring ASJ activities revealed that Ca2+ concentrations of ASJ were changed at around cultivated temperature when wild-type animals were cultivated 20 or 25 degree. Similar phenomenon was found in snb-1 mutant, that is a mutant defective in synaptic connection between neurons. In addition, the ratio changes of Ca2+ concentrations of ASJ in crh-1/CREB mutant cultivated at 20degC were smaller than wild-type animals. This abnormality of crh-1 mutant was rescued by the expression of crh-1 cDNA in ASJ specifically, suggesting that ASJ sensory neuron can memorize cultivated-temperature cell-autonomously that could be modified by CRH-1/CREB.In order to identify the downstream molecules of CREB, we performed DNA microarray analysis comparing between before and after temperature shift in wild-type animals. The expression levels of 112 genes were changed thee hours after temperature shift from 15 to 25 degree. The mutants of 19 genes were existed in stock center. Some mutants of the genes such as MAP kinase activated kinase, transmembrane glycoprotein, hypersensitive to pore forming toxin protein, and sphingomyelin synthetase showed abnormal phenotypes in speed of cold tolerance. We are analyzing whether these molecules are controlled by CREB in modulating the pathways on forming cold tolerance memory. (1) Ohta, Ujisawa et al., Nature commun., 2014.

Motomura, Haruka et al. (2021) International Worm Meeting "Whole-body neural circuit influences experience-dependent temperature acclimation"

Ohta, Akane, Motomura, Haruka, Ioroi, Makoto, Kuhara, Atsushi, Fujii, Satoko

[International Worm Meeting, 2021]

C. elegans stores temperature experiences and can induce temperature acclimation linked with cold tolerance (Ohta et al., Nature commun, 2014; Okahata et al., Science Advances, 2019). Here we found that a neural circuit containing ASJ sensoryneuron, PVQ and RMG interneurons, a head-to-tail neural circuit, is a central circuit in temperature acclimation. CREB/CRH-1 functions to regulate temperature acclimation in the ASJ thermosensory neuron and RMG head interneuron. Presynaptic signal enhancement by PKCgf revealed PVQ tail interneuron function as a bridge between the ASJ and RMG via glutamatergic signaling. Ca2+ imaging demonstrated that activities in ASJ, PVQ and RMG fluctuated with temperature changes, suggesting that these neurons are involved in temperature signaling. To identify the upstream sensoryneuron activating PVQ, we monitored PVQ neural activity of mutants defective in thermo-sensitivity of ASJ, ADL and ASG thermosensory neurons. We found that the Ca2+ levels of PVQ in tax-4(CNG channel) mutant defect in thermo-sensation of ASJ were higher than those in wild-type. Conversely, changes in Ca2+ levels of PVQ were decreased in deg-1 mutant impairing DEG/ENaC thermoreceptor of ASG thermosensory neuron. These results suggest that PVQ interneuron integrates temperature signaling from two upstream sensory neurons, ASG and ASJ. We hypothesized that ASG positively regulates the PVQ via the ASK sensory neuron, because this is the shortest pathway from ASG to PVQ. To examine whether ASK bridges between ASG and PVQ, we used reconstituted-caspase that can occur selective ablation of targeted cells. We found that the Ca2+ levels of PVQ in both ASG-ablated animals and ASK-ablated animals were decreased, suggesting that ASK bridges neural signaling between ASG and PVQ. Altogether, the ASJ and ASG which transmits an opposite temperature signaling to the tail interneuron PVQ. PVQ in turn releases glutamate to the RMG interneuron located in the head. We propose this body-wide circuit as the modulatory mechanism of temperature acclimation.

Okahata, M et al. (2015) International Worm Meeting "Genetic analysis of natural variations for cold habituation in C. elegans."

Okahata, M, Toyoda, A, Kuhara, A, Ohta, A, Minakuchi, Y

[International Worm Meeting, 2015]

Temperature is one of the essential environmental stimuli for living and proliferation of organisms on the earth. We are studying about natural variation of genes involved in temperature response by utilizing cultivation temperature shift assay in cold habituation (Ujisawa et al., Protocol Exchange, 2014). Most of 25 degree-grown wild-type N2 animals isolated from Bristol can not survive at 2 degree, whereas 15 degree-grown N2 animals can survive at 2 degree. We previously reported that only three hours after cultivation temperature shift from 25 to 15 degC, the cold habituation was newly established (Ohta, Ujisawa et al., Nature commun, 2014). This phenomenon is regulated by CREB in nervous system (Ohta, Ioroi et al., this meeting). We found that various wild-type strains isolated from various areas exhibited different cold habituation phenotype. Natural variations, CB4856 isolated from Hawaii and CB4853 isolated from California, slowly habituated to new temperature. By contrast, AB1 isolated from Australia rapidly habituated to new temperature. To identify the responsible gene polymorphisms for these variations, we used next generation DNA sequencer (NGS) and SNP analysis. We are mapping these polymorphisms by analyzing the recombinants between AB1 and CB4853, or between AB1 and CB4856. So far, one of the responsible polymorphisms was mapped onto chromosome I.We also found that natural variation strain CB4854 can not survive at 2 degree after cultivation at 17 degree, while N2 can survive at 2 degree after cultivation at 17 degree. Responsible gene polymorphism have been mapped onto -1.603~1.73cM region on chromosome X, by the next generation DNA sequencer and SNP analysis.