Toshiaki Suzuki et al. (2003) International Worm Meeting "Analysis of Ce-PARKIN in C. elegans"

Nobutaka Hattori, Toshiaki Suzuki, Keiji Tanaka, Yoshikuni Mizuno, Shohei MItani, Noriyuki Matsuda, Hideki Yashiroda, Toshiaki Kitami, Keiko Gengyo-Ando

[International Worm Meeting, 2003]

Autosomal recessive juvenile parkinsonism (AR-JP) is one of the most common forms of familial parkinsons disease characterized by selective loss of dopaminergic neurons in substantia nigra and the locus coeruleus. parkin is the causative gene of AR-JP. The human parkin gene encodes 465 amino acids with a ubiquitin-like domain in the amino-terminus and two RING finger motifs in the carboxy terminus. So far, various deletion mutations and point mutations have been discovered in patients of AR-JP, suggesting that the loss of function of Parkin is the cause of AR-JP. Recently we and others showed that Parkin has a ubiquitin-protein ligase activity and therefore suggested that the defect of protein degradation in the neurons of AR-JP patients (Shimura H. et al. Nat. Genet. 25, 302-5, 2000). To investigate the function of Parkin in vivo, we began to analyze the Ce-PARKIN of C. elegans. Two deletion mutations in parkin genes show no defect in their viabilities. The expression of Ce-PARKIN seems to be specific to subset of neurons. Therefore, we focused on the function of Ce-PARKIN in the neurons and the analysis is underway.

Hattori, Yuya et al. (2013) International Worm Meeting "Cell-level modeling and simulation of the pharyngeal pumping in Caenorhabditis elegans."

Suzuki, Michiyo, Hattori, Yuya, Tsuji, Toshio, Kobayashi, Yasuhiko

[International Worm Meeting, 2013]

The pharyngeal pumping in Caenorhabditis elegans is generated and controlled by the pharyngeal neurons and muscular cells. In this study, we proposed a simulation-based approach to estimate the mechanisms of oscillation generation in pharynx at cell level. To conduct the simulations, we previously developed a pharyngeal muscle model including 20 muscular cell models and 9 marginal cell models (Hattori, Y., et al, Artif. Life Robotics, 17, 2012). Output in each cell model was the membrane potential based on FitzHugh-Nagumo equations. These cell models were connected by gap junctions based on the actual connection structure of pharyngeal muscle in C. elegans. The gap junctions transmitted the outputs between cell models. The electropharyngeogram (EPG), which displays the summed activity of the electrophysiological responses of pharyngeal muscle cells and neurons, was used to measure the biological signals from pharyngeal pumping in C. elegans. In our simulation, we obtained the EPG using the outputs of individual cell models.

Matsuda, S. et al. (2015) International Worm Meeting "Detection and measurement of abnormal posture under stressful conditions in age-related mutants ."

Nitta, N., Matsuda, S., Yanase, S., Sakashita, T., Tamura, M., Suzuki, M., Ishii, N.

[International Worm Meeting, 2015]

Oxidative stress threatens cellular constructs including lipids, proteins and nucleic acids, and causes or influence apoptosis, degenerative diseases and aging [1]. Recently, we found an abnormal posture in short-lived mutants such as mev-1 and daf-16, exposed to hyperoxia. In this study, we detected the hyperoxia-induced abnormal posture in mev-1 and daf-16 mutants compared with wild-type N2 and long-lived age-1 strains. 4-day-old animals placed on a NGM agar plate with a fixed bacterial lawn were exposed to hyperoxia (90% of oxygen) overnight. After the exposure, some animals were immediately recorded as digital images with up to 400-fold magnification of the microscope. The images were analyzed using image-processing software, Wriggle Tracker and Move-tr/2D (Library Co., Ltd., Tokyo), by a previously published method [2]. The body line was skeletonized and evenly divided into 12 segments. Subsequently, X- and Y-coordinates of each point on the body were acquired. To evaluate the posture of the body, we introduced a novel standard, namely the 'posture index' as the absolute average of the relative angle between adjacent dividing points. As a result of this investigation, we can not only intuitively but also quantitatively and statistically understand a tendency of the behavior in various postural responses under stressful conditions in the short-lived mutants.References 1. Yanase S. and Ishii N. (2008) Hyperoxia exposure induced hormesis decreases mitochondrial superoxide radical levels via Ins/IGF-1 signaling pathway in a long-lived age-1 mutant of Caenorhabditis elegans, J. Radiat. Res. 49: 211-218.2. Hattori Y. et al. (2012) Theoretical and evolutionary parameter tuning of neural oscillators with a double-chain structure for generating rhythmic signals, Neural Compt. 24: 635-675.

Hattori, Y. et al. (2015) International Worm Meeting "Computer simulation of neuronal signals controlling the pharyngeal pumping motion in Caenorhabditis elegans."

Hattori, Y., Kobayashi, Y., Suzuki, M., Tsuji, T.

[International Worm Meeting, 2015]

The pharyngeal pumping in Caenorhabditis elegans is generated and controlled by the pharyngeal muscular cells and neurons. In this study, we proposed a simulation-based approach to estimate the control mechanisms of the pharyngeal pumping motion. To conduct the simulations, we previously developed a pharyngeal muscle model including 20 muscular cells and 9 marginal cells [1]. Output in each cell was represented by the membrane potential based on FitzHugh-Nagumo equations. These cells were connected by gap junctions based on the real connection structure of pharyngeal muscle in C. elegans. The gap junctions transmitted the outputs among cells. The electropharyngeogram (EPG), which shows the summed activity of the electrophysiological responses of pharyngeal muscle cells and neurons, was used to measure the biological signals from pharyngeal pumping in C. elegans. The model represented the EPG using the outputs of individual cells.We virtually input various electrical signals as neuronal signals to muscular cells in the model and calculated the EPG. As a result, some signal patterns induced the EPG which was similar to that observed in wild-type C. elegans. The cycle length of the EPG was synchronized with that of neuronal signals. These results suggest that neuronal signal could control the rhythm of pumping motion. Our approach shows potential for elucidating important signal factors (e.g., amplitude and cycle length) involved in the control of the pumping motion. Through a series of simulations, we confirmed the usefulness of the simulation-based approach for examining the control mechanisms of the pharyngeal pumping motion.[1] Hattori, Y., et al., Modeling of the pharyngeal muscle in Caenorhabditis elegans based on FitzHugh-Nagumo equations, Artificial Life and Robotics, Vol. 17, No. 2, pp. 173-179, 2012.

Suzuki, Michiyo et al. (2013) International Worm Meeting "Quantitative analysis of IR-induced effects on locomotion in Caenorhabditis elegans."

Hattori, Yuya, Sakashita, Tetsuya, Tsuji, Toshio, Suzuki, Michiyo, Kobayashi, Yasuhiko

[International Worm Meeting, 2013]

Background and purpose: C. elegans is a good in vivo model system to examine radiobiological effects. We have previously examined the effects of ionizing radiation (IR) on locomotion in C. elegans using 'body bends' (the number of bends counted in the anterior body region at 20-s intervals) [1] and reported an IR-induced reduction in motility [2],[3]. However, the degree of motility in each region of the body has not been established. In the present study, we employed a video-based analysis and investigated the IR-induced effects on locomotion in more detail. Irradiation and video-based analysis: Young adult wild-type C. elegans were placed on a NGM plate with a bacterial lawn (food) and irradiated with graded single doses (0-1.5 kGy) of 60Co g-rays. Immediately after irradiation, animals were transferred to a NGM plate, either with or without food. The movements of five or more animals placed on each plate were video-recorded. The video images were analyzed off-line based on a previously published method [4]. Briefly, after binarization and denoising, the body line was skeletonized and evenly divided into 12 segments; X- and Y-coordinates of each point on the body were subsequently acquired. To evaluate the motility of each point on the body, the moving distance of each of 13 points over a 5 s period was calculated using the X- and Y-coordinates. In addition, we introduced a novel standard, namely the straight distance from head to tail, to evaluate the body form. Results: Under the -food condition, the moving distance of irradiated animals was reduced in a dose-dependent manner at each point on the body, and there was no difference between the effects on each region of the body. The dose-dependent reduction in locomotion was also observed in animals under the +food condition. Furthermore, we evaluated body form and found that IR-induced quantitative changes in body form. References: [1] Sawin, E.R., et al. (2000) Neuron 26, [2] Sakashita, T., et al. (2008) J. Radiat. Res. 49, [3] Suzuki, M., et al. (2009) J. Radiat. Res. 50, [4] Hattori, T., et al. (2012) Neural Comput. 24.