FY2015 Annual Report

Principal Investigator: Ichiro Maruyama
Research Theme: Information Processing by Life

Abstract

In order to survive, animals must closely monitor environmental changes, and must keep the memory as experiences to adjust their behavior to the environment. We are interested in understanding how neuronal networks process environmental information to regulate animal behaviors, including decision-making, learning and memory. In previous years, we developed protocols to study associative learning and memory in the nematode Caenorhabditis elegans as a model organism. C. elegans is innately attracted to propanol, a short-chain alcohol, and avoids acid such as pH 4. After repeated conditioning C. elegans with propanol and acid, it associates the two stimuli and avoid propanol. C. elegans retains the memory up to 24 hours as long-term associative memory. In the present fiscal year, we have been trying to identify neuronal circuits responsible for the memory trace in the C. elegans nervous system by using multiple techniques including genetic rescue experiments and Ca2+ imaging analysis of neuronal activity. Optogenetics is also used to induce memories by expressing an artificial ion channel such as channelrhodopsin in specific neurons. Towards an understanding of adult onset neurodegenerative diseases, we have tried to isolate C. elegans mutants using forward genetics. Electrophysiology has been used to understand how electrical signals are transmitted along neurites of major gustatory sensory neurons. To understand decision-making in C. elegans, we also started analysis of its behavior on salt gradients.

We are also interested in understanding how neurons/cells detect extracellular information and transmit it into inside the cell. For the last three decades, ligand-induced dimerization has been widely thought to be a common property of transmembrane signaling by receptors for all known growth factor and cytokines, among others. In previous years, however, we found that receptors for epidermal growth factor (EGF), nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) have a preformed, yet inactive, dimeric structure prior to ligand binding. Based on the results, we proposed an alternative ‘rotation model’, in which ligand binding to the extracellular domains induces a rotation of the transmembrane domains parallel to the plane of the membrane. This activates the intracellular domains, which often encode or physically interact with a kinase, by rearranging their dimeric structures. To examine the model, we are currently trying to determine three dimensional structures of the receptor dimers. We are also analyzing co-operative interaction between EGF and its receptor EGFR, which is observed only in dimers.

These results provide insights into the molecular mechanism underlying information transfer from the outside of neurons/cells to the inside, as well as an understanding of neuronal networks responsible for associative learning and memory. These findings may also be invaluable in developing pharmaceuticals for human diseases such as cancers and mental diseases.

1. Staff

  • Rehab Abdelhamid, Staff Scientist (until October 31, 2015)
  • Andrew Mugo, Postdoctoral Scholar
  • Takashi Murayama, Staff Scientist
  • Hitomi Ohtaki, Research Unit Administrator
  • Endang Rinawati Purba, Postdoctoral Scholar
  • Eiichiro Saita, Technical Staff
  • Vimbai Samukange, Postdoctoral Scholar (from August 1, 2015)

2. Graduate and other students

  • Mohamed Abdelhack, M. Sc. Student (until September 30, 2015)
  • Tosif Ahamed, PhD Student
  • Kazuto Kawamura, PhD Student
  • Viktoras Lisicovas, PhD Student
  • Benjamin Singer, Research Intern (July 2 -August 30, 2015)

3. Collaborations

3.1 Functional analyses of small G protein and their downstream proteins

  • Type of collaboration: Joint research
  • Researchers:
    • Ken-ichi Kariya, University of the Ryukyus
    • Tsuyoshi Asato, University of the Ryukyus
    • Kimiko Nonaka, University of the Ryukyus

3.2 Study of signal transduction pathways that regulate cellular functions

  • Type of collaboration: Joint research
  • Researchers:
    • Ken-ichi Kariya, University of the Ryukyus
    • Tsuyoshi Asato, University of the Ryukyus
    • Kimiko Nonaka, University of the Ryukyus

3.3 Social interaction and anxiety of genetically modified mice

  • Type of collaboration: Joint research
  • Researchers:
    • Ken-ichi Kariya, University of the Ryukyus
    • Tsuyoshi Asato, University of the Ryukyus
    • Kimiko Nonaka, University of the Ryukyus

3.4 Analysis of Rap2 function in skin wound healing

  • Type of collaboration: Joint research
  • Researchers:
    • Ken-ichi Kariya, University of the Ryukyus
    • Tsuyoshi Asato, University of the Ryukyus
    • Kimiko Nonaka, University of the Ryukyus

4. Activities and Findings

4.1 Project Aims

All forms of life are separated from their environments by cell membranes, and all neurons/cells have cell-surface receptor proteins that span the membrane in order to transmit external information, such as environmental changes and cell-cell communications, into inside the cell. Such information flow is fundamental for all forms of life, from bacteria to humans. Dysregulation of cell surface receptor molecules causes a variety of impairments, including mental and developmental diseases and cancer in humans. (1) We wish to understand the information processing through cellular networks. Specifically, we want to know how the external information is sensed and transmitted through sensory neurons, how it is processed by the nervous system, and how it controls animal behaviors, including decision-making, learning and memory. (2) We wish also to understand at the molecular level how the external information is sensed and transmitted into the inside of neurons/cells by cell-surface receptors. We also seek to know how the information is processed, how it is transferred to other parts of the cells, and how it regulates other cellular activities.

4.2 Progress Report

4.2.1. Information processing by the nervous system

4.2.1.1. Aversive olfactory learning and memory in C. elegans.

Background

C. elegans is a model organism suited for the study of learning and memory. The hermaphrodite nervous system consists of only 302 neurons, and neural circuits, chemical synapses, and electrical gap junctions of these invariant neurons have completely been reconstructed from serial thin sections of electron micrographs. The worm body is transparent throughout its life so that neural activities can directly be observed using Ca2+-sensitive or voltage-sensitive fluorescent proteins in living animals.

Associative learning in C. elegans was first suggested from the finding that worms return to their temperature of cultivation if they had food at that temperature. Most of learning paradigms in C. elegans are based on pairing chemical cues with food or starvation. Rather than pairing chemical cues with food or starvation, however, it would be preferable for subsequent analysis of neural circuits responsible for associative learning and memory to use two defined chemical cues for conditioning of animals in associative learning paradigms.

Progress

In previous years, we also developed protocols for classical conditioning of C. elegans with 1-propanol, as a CS and hydrochloride (HCl), pH 4.0, as a US. Before conditioning, animals were innately attracted to 1-propanol, and avoided HCl in chemotaxis assays. However, after spaced or massed training, animals were either not attracted at all or were repelled by propanol on the assay plate. The memory after the spaced training was retained for 24 hours, while the memory after the massed training did not even persist for 3 hours. Animals pretreated with transcription and translation inhibitors failed to form the memory by spaced training, whereas the memory after massed training was not significantly affected by inhibitors and was sensitive to cold-shock anesthesia. Furthermore, memory after spaced training was reasonably disrupted by extinction learning, in which the worm is repeatedly exposed to the CS in the absence of US. Therefore, memories after spaced and massed training can be classified as LTM and STM, respectively. Consistently, like other organisms including Aplysia, Drosophila, and mice, C. elegans mutants defective in nmr-1, encoding an NMDA receptor subunit, failed to form both LTM and STM, while mutations in crh-1 encoding the CREB transcription factor affected only LTM (Amano & Maruyama, 2011). The NMR-1 protein is only expressed in six pairs of interneurons. Therefore, we hypothesize that neurons responsible for the associative memory trace can be identified by rescuing nmr-1 mutants by making transgenic animals. In the present fiscal year, we have made transgenic animals that are expressing NMR-1 in a neuron-specific manner. We are currently examining whether the transgenic animals can form the associative memory or not.

4.2.1.2. Associative learning and memory induced by optogenetics

Optogenetics enables manipulation of neuronal activity with high temporal and spatial precisions, and has been used for aversive and appetitive conditionings in Drosophila and for fear conditioning in rats. As described above, C. elegans can also form long-term associative memory between attractive 1-propanol as a CS and acid as a US. We have previously shown that light stimulation of ASH nociceptive neurons that express channelrhodopsin-2 (ChR2) can substitute acid in this paradigm, using a setup (Figure 1A) capable of simultaneous optogenetic and odor stimulation of C. elegans. The setup also allows us to monitor behaviors of a group of animals. In this fiscal year, we have established semi-optogenetic conditioning paradigm using diacetyl as a CS and blue light as a US (Figure 1B).

Figure 1. Optogenetic approach to induced associative memory. (A) Animals on an agar plate used for conditioning. (B) Associative learning between an olfactory chemical, diacetyl, and light; or between 1-propanol and light.

4.2.1.3. Adult-onset neuromuscular dysfunction.

Background

Every disease has a typical clinical time-course; some diseases begin to show symptoms during childhood while other diseases seemingly begin in late adulthood. In inherited cases of adult-onset diseases, the causative mutation is present from birth, but major symptoms occur in late life. How can a mutation start to cause symptoms only after a long time has passed? If we can better understand this process, we may be able to find better ways to treat adult-onset diseases.

        C. elegans is a model organism that has been used to identify key genes involved in complex biological processes. For example, a C. elegans forward genetic screen led to the identification of a mutation in the age-1 gene that causes a 40% extension of mean lifespan (Friedman and Johnson, Genetics 1988). The identification of a single mutation that had a large effect on aging was surprising because the interaction of many genes was expected to affect aging. Friedman and Johnson’s screen demonstrated that a genetic screen of C. elegans mutants is advantageous for identifying key regulators of complex biological processes. We focused on adult-onset neuromuscular dysfunction, and screened for worms that lost their locomotor ability after reaching adulthood. We hope to identify new genes involved in adult-onset neuromuscular dysfunction during disease and normal aging.

Progress

From our previous work, we isolated 22 adult-onset motor deficit mutants following ethyl methanesulfonate (EMS) mutagenesis. We chose the A20-1 mutant line as the first mutant to study because it showed no obvious morphological abnormalities and it demonstrated a relatively strong adult-onset motor deficit phenotype. The adult-onset motor deficit phenotype was maintained even after four backcrosses. We aimed to identify the causative mutation by the EMS variant density mapping approach. Due to a lower frequency of homologous recombinations between physically close genomic regions, a higher density of EMS mutations should remain near the causative mutation site(s) after backcrossing. We conducted whole-genome sequencing on the unbackcrossed A20-1 mutant line and the backcrossed A20-1 mutant line (Figure 2). In the backcrossed A20-1 mutant line, one region on Chromosome 1 and one region on Chromosome 4 retained high densities of EMS-induced mutations sites (Figure 2B). We predict the causative mutation site(s) to be located in one or both of these regions.

Figure 2. Comparison of mutation frequencies in A20-1 line before and after backcrossing. (A) Number and position of EMS-induced mutations in the unbackcrossed A20-1 mutant line. (B) Number and position of EMS-induced mutations in the 4x backcrossed A20-1 mutant line.

4.2.1.4. Electrophysiology of major gustatory sensory neurons.

A lack of Na+ channels required for the generation of action potentials in C. elegans neurons has previously believed passive propagation of electrical signals along neurites. Recently, however, a Ca2+-dependent action potential or plateau potential has been reported in RMD neurons of C. elegans. A channel responsible for the active propagation of membrane potentials has not been identified. The C. elegans genome encodes genes for L-type, P/Q-type and T-type voltage-gated calcium channels (VGCCs). egl-19 and unc-2 genes encode an L-type VGCC and a P/Q-type VGCC, respectively. To investigate their roles in chemo-sensation, Ca2+ transients in a pair of ASE chemosensory neurons, ASEL and ASER, of wild-type and mutants defective in egl-19 and unc-2 were analyzed upon environmental changes of NaCl concentrations. In wild type and unc-2 animals, ASEL soma and ASER soma were strongly activated by an increase and decrease of NaCl concentrations, respectively (Figures 3a, 3d). In egl-19 animals, Ca2+ transient in ASEL soma was markedly reduced, whereas ASER soma showed equivalent Ca2+ transients to that of wild type (Figures 3e, 3f). However, we could observe Ca2+ transients in the egl-19 ASEL cilium (Figures 3g, 3h), suggesting that Ca2+ influx into the ASEL cilia occurs normally. These results indicate that the EGL-19 L-type VGCC is essential for electrical signal propagation along the ASEL dendrite.

Figure 3. Ca2+ transients in ASE neurons expressing GCaMP3 in response to an increase or decrease of NaCl concentrations. Mean values of DF/F0 in wild-type ASEL, n = 11 (a), wild-type ASER, n = 16 (b), unc-2 ASEL, n = 13 (c), unc-2 ASER, n = 20 (d), egl-19 ASEL, n = 14 (e), egl-19 ASER, n = 14 (f), and in the sensory cilium of egl-19 ASEL, n = 12 (g) and egl-19 ASER, n = 18 (h). Gray areas indicate s.e.m.

4.2.1.5. Biogenic monoamines in C. elegans decision making.

Goal-directed behaviors, such as chemotaxis and thermotaxis, are one of the simplest forms of decision-making behaviors present in a wide variety of animals. Chemotaxis has been well studied in C. elegans. Monoamines are known to be involved in behavioral plasticity. Chemotaxis of C. elegans begins with an approach phase in which the animal rapidly ascends to the peak of chemical gradients such as nutrients. C. elegans then accumulates on the top of the gradient for some time and finally leaves the gradient. The accumulation and the subsequent escape from the gradient can be considered a decision-making behavior as it can change depending on the context. When the animal is pre-exposed to the attractant together with an aversive stimulus, then the accumulation period is significantly shorter than normal. When a mild attractant is pre-exposed in combination with an appetitive stimulus, conversely, the accumulation period is longer. If monoamines are involved in this decision-making, monoamine mutants should have defects in this behavior. To test this hypothesis, the chemotaxis behavior of cat-2 mutants defective in the synthesis of dopamine was assayed. Figure 4A shows an agar plate with 12 spots of NaCl separated by 2 cm from each other on a 9.5-cm Petri dish. Figure 4B shows a trajectory of a wild-type animal, of which pirouettes and runs are colored in pink and black, respectively. From each track, the amount of time spent on the attractant spot and the pirouette probability as a function of the rate of concertation changes, dc/dt, were measured. On average, cat-2 mutants spend less time on the concentration peak of a NaCl gradient, compared to wild-type animals. Similar accumulation times are also observed when wild-type animals pretreated with Raclopride (a D2 dopamine receptor antagonist) are tested. Dopamine-pretreated cat-2 mutants spend a significantly longer time on the highest peak of the NaCl gradient. The cat-2 animals made significantly fewer numbers of pirouettes, compared to wild-type animals. This defect was partially rescued by pretreatment of the mutants with dopamine.

        

Figure 4. (A) An agar plate with 12 NaCl spots, which was used for chemotaxis assay. NaCl gradients were generated by spotting an hour before the assay. (B) A typical trajectory of wild-type animals, of which pirouettes and runs are colored in pink and black, respectively.

 

4.2.2. Information processing by neurons/cells

4.2.2.1. Background.

The bacterial cell-surface receptor, Tar, recognizes aspartate molecules in the environment, and directs bacterial cells toward higher concentrations of the attractant as a nutrient, or toward lower concentration of repellents, such as nickel and cobalt ions. This transmembrane signaling is mediated by Tar in its homodimeric form on the cell surface. We have previously shown that Tar activity is regulated by its ligands, which bind to the extracellular domain of the receptor and lock/freeze the rotational movement of the receptor’s transmembrane domains parallel to the plane of the membrane (Maruyama et al., 1995). This locking/freezing of the rotation at one position by the attractant is likely to inhibit the associated histidine kinase CheA, while the locking/freezing at another position by the repellent seems to activate the kinase activity (the rotation model).

We also analyzed the molecular mechanism underlying activation of the human epidermal growth factor receptor (EGFR) family of cell-surface receptor tyrosine kinases, also known as ErbB or HER (Moriki et al., 2001). EGF/ErbB receptors play a pivotal role in the development of organisms, and are frequently implicated in human cancers. Furthermore, these receptors also regulate neural activities, and mutations of these receptor genes are frequently associated with mental diseases. The receptor family consists of four members, EGFR/ErbB1, ErbB2/Neu/HER2, ErbB3/HER3 and ErbB4/HER4, and has a large (~620 amino acid) extracellular ligand-binding region, a single, transmembrane alpha-helix, and an intracellular region containing the tyrosine kinase and its regulatory domain. They form a network of homo- and heterodimers. ErbB2 can only be regulated indirectly, and is thought to be the preferred heterodimerization partner for other ErbB receptors. ErbB3, on the other hand, must associate with an ErbB family member that has an active tyrosine kinase in order to respond to its own ligand, neuregulin (NRG).

Ligand-induced dimerization has widely been thought to be a property common to the transmembrane signaling by all known growth factor receptors including the EGF/ErbB receptors (Ligand-induced Dimerization Model). According to the model, receptor dimerization is responsible for autophosphorylation of the intrinsic kinase activity, which is mediated by an intermolecular process. The model holds that ligand binds to the monomeric form of the receptor, inducing its dimerization and resulting activation. However, it remains controversial whether the receptor actually has a monomeric or dimeric structure prior to ligand binding

Using chemical cross-linking and sucrose density-gradient centrifugation, we recently discovered that in the absence of bound ligand, EGFR has the ability to form a dimer and that the majority (>80%) of receptors exist as preformed dimers on the cell surface. We also analyzed receptor dimerization by inserting cysteine residues at strategic positions along the longitudinal axis of the alpha-helical extracellular juxtamembrane region. Mutant receptors spontaneously formed disulfide bridges and transformed NIH3T3 cells in the absence of ligand, depending upon the positions of the cysteine residues inserted. Kinetic analysis of disulfide bonding indicates that ligand binding induces flexible rotation or twist of the juxtamembrane region of the receptor in a plane parallel with the lipid bilayer. The binding of an ATP competitor to the intracellular kinase domain also induced similar flexible rotation/twist of the juxtamembrane region. All disulfide-bonded dimers had flexible ligand-binding domains with the same biphasic affinities for ligand as the wild type. Based on these results, we have proposed an alternative ‘rotation/twist’ model (Fig. 3) for the molecular mechanism of EGF receptor activation, in which ligand binding to the flexible extracellular domains of the receptor dimer induces rotation/twist of the juxtamembrane regions, hence the transmembrane domains, rearrange the kinase domains for the receptor activation. Indeed, this rotation/twist model (Moriki et al., 2001; Tao and Maruyama, 2008) is consistent with recent results by others in which the receptor kinase, transmembrane and unactivated extracellular domains are shown to have homodimeric structures.

              

Figure 5. “Rotation model” for molecular mechanism underlying activation of transmembrane cell-surface receptors including EGFR (Maruyama, 2015).

To support the ‘rotation’ model, we have recently determined preformed, homo- and heterodimeric structures of EGFR and ErbB2 at physiological expression levels (~104 molecules per cell), using fluorescence microscopy, fluorescence resonance energy transfer (FRET) and fluorescence cross-correlation spectroscopy (FCCS) (Liu et al., 2007). When fluorescent protein (FP)-fused EGFR and ErbB2 were expressed on the cell surface of Chinese hamster ovary cells at physiological expression levels, FRET was detected between the donor and acceptor FPs in the absence of ligand. Furthermore, cross-correlation between FPs separately fused to EGFR or ErbB2 was also observed by FCCS, indicating that EGFR and ErbB2 molecules diffuse together as homo- or heterodimers in the cell membrane. These results demonstrate that prior to ligand binding, the cell-surface receptors can spontaneously form homo- and heterodimers, irrespective of their expression levels ranging from ~2 x 104 to ~5 x 106 molecules per cell.

Furthermore, we have been analyzing preformed homo- and heterodimeric structures between all the members, EGFR, ErbB2, ErbB3, and ErbB4, of the receptor family by employing bimolecular fluorescence complementation (BiFC) assay. We have found that all members display preformed, yet inactive, homo- and heterodimeric structures in the absence of bound ligand (Tao & Maruyama, 2008). Ligand-independent dimerization of EGF/ErbB receptors occurs in the endoplasmic reticulum (ER) before newly synthesized receptor molecules reach the cell surface. Furthermore, we have also found that ErbB3 was localized in the nucleus when expressed alone or together with ErbB4. When coexpressed with EGFR or ErbB2, however, ErbB3 was located in the plasma membrane. These results indicate that all the EGF/ErbB receptors exist as homo- and heterodimers before ligand binding, consistent with the ‘rotation/twist’ model. ErbB receptors exist as dimers on the cell surface, mainly through interaction between their transmembrane domains, intracellular kinase domains and C-terminal tails. Receptor dimers have flexible extracellular domains, and perhaps can take two major conformations, closed (tethered) and open (untethered) states. Ligand binding to the open form of the receptor dimer stabilizes the extracellular domains, resulting in approximately 140° rotation or twist of the transmembrane domains about its helix axis parallel to the plane of the cell membrane, dissociate the symmetric back-to-back kinase domains, and then rearrange the kinase domains to take head-to-tail asymmetric configuration for the receptor activation.

As described above, different cell-surface receptors, bacterial Tar and human EGF/ErbB receptors, seem to be similarly regulated by their ligands in order to transmit the extracellular information to the inside of the cell. Ligand binding regulates the rotation of the receptor’s transmembrane domain parallel to the plane of the plasma membrane. Therefore, we have been continuing to test “the rotation model” for the molecular activation mechanism of other cell-surface receptors, including Tar, EGF/ErbB receptors and neurotrophin receptors. Indeed, we have recently elucidated that the neurotrophin receptor TrkA is present as a preformed, yet inactive, dimer in living cells (Shen & Maruyama, 2011). We have also previously found that the intracellular domain of the EGF/ErbB receptors plays a crucial role in the spontaneous formation of receptor dimers (Tao & Maruyama, 2008). Thus, an increasing number of studies demonstrate that many transmembrane receptors, which include receptors previously thought to be activated by ligand-induced receptor dimerization, exist as preformed, yet inactive, homo- and heterodimers in living cells. These receptors include the aspartate receptor Tar, EGF/ErbB receptor family members, erythropoietin receptor (EpoR), growth hormone receptor (GHR), Toll-like receptor-9 (TLR9), natriuretic peptide receptor A (NPRA), nerve growth factor (NGF) receptor TrkA, and brain-derived neurotrophic factor (BDNF) receptor TrkB. In the cases of Tar, EGFR, GHR, and NPRA, it has been proposed that ligand binding induces or stabilizes the rotation of transmembrane domains of preformed receptor dimers for the rearrangement of intracellular domains necessary for activation (Figure 5; Maruyama, 2015).

4.2.2.2. Structural analysis of EGFR.

Toward determination of three-dimensional structures of EGFR, we have been trying to purify full-length EGFR. A plasmid encoding full-length EGFR has successfully been transfected to HEK293 culture cells. The expression level of EGFR was high when transfected by using PEI and DNA in ratio 1:3. EGFR has successfully been purified from 1.0-gram cells, and the yield was 0.5 mg/ml with purity 83%. The activity of EGFR protein was confirmed by phosphorylation assay in the presence of EGF ligand and ATP. 

 

4.2.2.3. Structures of the bacterial aspartate receptor.

Three-dimensional (3D) structures of the extracellular ligand-binding domain of the bacterial aspartate receptor Tar, with and without bound aspartate, were determined 20 years ago. It has been reported that the transmembrane domain of Tar shifts vertically 1-2 Å upon binding of aspartate, an attractant for the bacteria. Based on this result, “The piston model” has been proposed as a molecular mechanism underlying activation of Tar by aspartate binding. An alternative “rotation model” has been proposed, in which repellent binding induces the rotation of the transmembrane parallel to the plane of the membrane (Maruyama et al., 1995). According to “the rotation model”, Tar with and without bound aspartate take the similar structure to each other, the most stable structure among rotationally flexible structures. As descried above, this is consistent with the 3D structures of the extracellular domain of Tar with and without bound aspartate. To test “the rotation model”, crystallization of the Tar extracellular domain with a bound repellent, antagonist and agonist have been tried this fiscal year. Sixteen crystals soaked with either of the ligand have been analyzed but the electron density map of the ligand could not be found yet. 

5. Publications

5.1 Journals

  1. Maruyama, I. N. Activation of transmembrane cell-surface receptors via a common mechanism? The "rotation model". Bioessays (2015) 37: 959-967.
  2. Murayama, T. and Maruyama, I.N. Alkaline pH sensor molecules. J Neurosci Res (2015) 93: 1623-1630.

5.2 Oral and Poster Presentations

  1. Ito, S. Long-term associative memory in Caenorhabditis elegans. C. elegans 2015 20th International Meeting. UCLA, CA, USA (June 24-28, 2015)
  2. Kawamura, K., et al. A forward genetic screen for adult-onset motor deficits in C. elegans. C. elegans 2015 20th International Meeting. UCLA, CA, USA (June 24-28, 2015)
  3. Lisicovas, V. and Maruyama, I.N. Long-term olfactory associative memory induction by optogenetic stimulation of ASH neuron. C. elegans 2015 20th International Meeting. UCLA, CA, USA (June 24-28, 2015)
  4. Shindou, T., et al. Electrophysiological properties of ASE neurons. C. elegans 2015 20th International Meeting. UCLA, CA, USA (June 24-28, 2015)
  5. Ito, S. and Maruyama I.N. Long-term associative memory in Caenorhabditis elegans. The 38th Annual Meeting of the Japan Neuroscience Society. Kobe, Japan (July 28-31, 2015)
  6. Ito, S. Short- and long-term associative olfactory memory in Caenorhabditis elegans. BMB (Biochemistry and Molecular Biology) 2015. Kobe, Japan (December 1-4, 2015)
  7. Ito, S. and Maruyama, I.N. Long-term associative memory in Caenorhabditis elegans. Neurscience 2015. Chicago, USA (October 17-21, 2015)
  8. Murayama, T. and Maruyama, I.N. Analysis of neural functions for chemotaxis to alkaline pH in C. elegans. BMB (Biochemistry and Molecular Biology) 2015. Kobe, Japan  (December 1-4, 2015)

6. Meetings and Events

6.1 Seminar

Title: Biochemical Analysis on the Interaction of Human Matrix Metalloproteinase 7 and Thermolysin with 8-Anilinonaphthalene 1-Sulfonate, Heparin, and Cholesterol Sulfate
  • Speaker: Vimbai Samukange
  • Date: May 18, 2015
  • Venue: OIST Lab1 C015
Title: Long-term associative memory in Caenorhabditis elegans
  • Speaker: Satomi Ito
  • Date: August 7, 2015
  • Venue: OIST Center Building C210
Title: MChemosensory function of desert toads
  • Speaker: Takatoshi Nagai
  • Date: November 12, 2015
  • Venue: OIST Lab1 C016