Photoresponse in the Ciliated Protozoan Colpoda cucullus

Kawano, Noriyuki, Funadani, Ryoji, Arikawa, Mikihiko, Harada, Tetsuo, Suizu, Futoshi, Matsuoka, Kou, Matsuoka, Tatsuomi (2017): Photoresponse in the Ciliated Protozoan Colpoda cucullus. Acta Protozoologica 56 (1): 1-7, DOI: 10.4467/16890027AP.17.001.6965, URL: https://www.mendeley.com/catalogue/0cd0b706-68e1-3ba9-9e25-c545a0f41b65

Donepezil, Anti-Alzheimer's Disease Drug, Prevents Cardiac Rupture during Acute Phase of Myocardial Infarction in Mice

Background: We have previously demonstrated that the chronic intervention in the cholinergic system by donepezil, an acetylcholinesterase inhibitor, plays a beneficial role in suppressing long-term cardiac remodeling after myocardial infarction (MI). In comparison with such a chronic effect, however, the acute effect of donepezil during an acute phase of MI remains unclear. Noticing recent findings of a cholinergic mechanism for anti-inflammatory actions, we tested the hypothesis that donepezil attenuates an acute inflammatory tissue injury following MI. Methods and Results: In isolated and activated macrophages, donepezil significantly reduced intra- and extracellular matrix metalloproteinase-9 (MMP-9). In mice with MI, despite the comparable values of heart rate and blood pressure, the donepezil-treated group showed a significantly lower incidence of cardiac rupture than the untreated group during the acute phase of MI. Immunohistochemistry revealed that MMP-9 was localized at the infarct area where a large number of inflammatory cells including macrophages infiltrated, and the expression and the enzymatic activity of MMP-9 at the left ventricular infarct area was significantly reduced in the donepezil-treated group. Conclusion: The present study suggests that donepezil inhibits the MMP-9-related acute inflammatory tissue injury in the infarcted myocardium, thereby reduces the risk of left ventricular free wall rupture during the acute phase of MI

A non-neuronal cardiac cholinergic system plays a protective role in myocardium salvage during ischemic insults.

BACKGROUND: In our previous study, we established the novel concept of a non-neuronal cardiac cholinergic system--cardiomyocytes produce ACh in an autocrine and/or paracrine manner. Subsequently, we determined the biological significance of this system--it played a critical role in modulating mitochondrial oxygen consumption. However, its detailed mechanisms and clinical implications have not been fully investigated. AIM: We investigated if this non-neuronal cardiac cholinergic system was upregulated by a modality other than drugs and if the activation of the system contributes to favorable outcomes. RESULTS: Choline acetyltransferase knockout (ChAT KO) cells with the lowest cellular ACh levels consumed more oxygen and had increased MTT activity and lower cellular ATP levels compared with the control cells. Cardiac ChAT KO cells with diminished connexin 43 expression formed poor cell-cell communication, evidenced by the blunted dye transfer. Similarly, the ChAT inhibitor hemicholinium-3 decreased ATP levels and increased MTT activity in cardiomyocytes. In the presence of a hypoxia mimetic, ChAT KO viability was reduced. Norepinephrine dose-dependently caused cardiac ChAT KO cell death associated with increased ROS production. In in vivo studies, protein expression of ChAT and the choline transporter CHT1 in the hindlimb were enhanced after ischemia-reperfusion compared with the contralateral non-treated limb. This local effect also remotely influenced the heart to upregulate ChAT and CHT1 expression as well as ACh and ATP levels in the heart compared with the baseline levels, and more intact cardiomyocytes were spared by this remote effect as evidenced by reduced infarction size. In contrast, the upregulated parameters were abrogated by hemicholinium-3. CONCLUSION: The non-neuronal cholinergic system plays a protective role in both myocardial cells and the entire heart by conserving ATP levels and inhibiting oxygen consumption. Activation of this non-neuronal cardiac cholinergic system by a physiotherapeutic modality may underlie cardioprotection through the remote effect of hindlimb ischemia-reperfusion

Identification of a mastigoneme protein from Phytophthora nicotianae

Tripartite tubular hairs (mastigonemes) on the anterior flagellum of protists in the stramenopile taxon are responsible for reversing the thrust of flagellar beat and for cell motility. Immunoprecipitation experiments using antibodies directed towards mastigonemes on the flagella of zoospores of Phytophthora nicotianae have facilitated the cloning of a gene encoding a mastigoneme shaft protein in this Oomycete. Expression of the gene, designated PnMas2, is up-regulated during asexual sporulation, a period during which many zoospore components are synthesized. Analysis of the sequence of the PnMas2 protein has revealed that, like other stramenopile mastigoneme proteins, PnMas2 has an N-terminal secretion signal and contains four cysteine-rich epidermal growth factor (EGF)-like domains. Evidence from non-denaturing gels indicates that PnMas2 forms large oligomeric complexes, most likely through disulphide bridging. Bioinformatic analysis has revealed that Phytophthora species typically contain three or four putative mastigoneme proteins containing the four EGF-like domains. These proteins are similar in sequence to mastigoneme proteins in other stramenopile protists including the algae Ochromonas danica, Aureococcus anophagefferens and Scytosiphon lomentaria and the diatoms Thalassiosira pseudonana and T. weissflogii.This study was conducted with the support of the Australian Research Council

Fig. 3 in Photoresponse in the Ciliated Protozoan Colpoda cucullus

Fig. 3. Photoresponse of C. cucullus Nag-1 to an increase or decrease in white light intensity. (a) Side-view of a chamber to observe the photoresponse of the cells. The cell suspension was kept 1-mm thick. (b) The temperature of the cell suspension after stimulation light was applied (arrow). (c) Directional changes (photophobic response) of the cells to a sudden increase (c-1) or decrease (c-2) in white light intensity. Prior to "ON" and "OFF" stimulation, the cells were adapted for 1 min in the background dim-light (0.65 W·m–2) and bright light (7 W·m–2), respectively. The cells responded by turning more than 90 degrees in 2 s after light stimulation was expressed as the percentage of the total number of tested cells (100 cells). (d) Alteration in steady-state forward swimming velocity of the cells induced by continuous light stimulation (photokinetic response). Prior to "ON" and "OFF" stimulation, the cells were adapted for 1 min in dim-light (0.65 W·m–2) and bright light (7 W·m–2), respectively. (d-1) Time course of forward swimming velocity after the onset of step-up light stimulation. The shaded circles indicate the swimming velocity at 1 s before light intensity was increased. Asterisks indicate significant differences in the swimming velocity before light stimulation (shaded circle) (p <0.05, Mann-Whitney test). (d-2) Time course of forward swimming velocity after the onset of step-down light stimulation. The open circle is swimming velocity at 1 s before light intensity is decreased.Published as part of Kawano, Noriyuki, Funadani, Ryoji, Arikawa, Mikihiko, Harada, Tetsuo, Suizu, Futoshi, Matsuoka, Kou & Matsuoka, Tatsuomi, 2017, Photoresponse in the Ciliated Protozoan Colpoda cucullus, pp. 1-7 in Acta Protozoologica 56 (1) on page 5, DOI: 10.4467/16890027AP.17.001.6965, http://zenodo.org/record/835688