The N-terminal TOG domain of Arabidopsis MOR1 modulates affinity for microtubule polymers

Microtubule-associated proteins of the highly conserved XMAP215/Dis1 family promote both microtubule growth and shrinkage, and move with the dynamic microtubule ends. The plant homologue, MOR1, is predicted to form a long linear molecule with five N-terminal TOG domains. Within the first (TOG1) domain, the mor1-1 leucine to phenylalanine (L174F) substitution causes temperature-dependent disorganization of microtubule arrays and reduces microtubule growth and shrinkage rates. By expressing the two N-terminal TOG domains (TOG12) of MOR1, both in planta for analysis in living cells and in bacteria for in vitro microtubule-binding and polymerization assays, we determined that the N-terminal domain of MOR1 is crucial for microtubule polymer binding. Tagging TOG12 at the N-terminus interfered with its ability to bind microtubules when stably expressed in Arabidopsis or when transiently overexpressed in leek epidermal cells, and impeded polymerase activity in vitro. In contrast, TOG12 tagged at the C-terminus interacted with microtubules in vivo, rescued the temperature-sensitive mor1-1 phenotype, and promoted microtubule polymerization in vitro. TOG12 constructs containing the L174F mor1-1 point mutation caused microtubule disruption when transiently overexpressed in leek epidermis and increased the affinity of TOG12 for microtubules in vitro. This suggests that the mor1-1 mutant protein makes microtubules less dynamic by binding the microtubule lattice too strongly to support rapid plus-end tracking. We conclude from our results that a balanced microtubule affinity in the N-terminal TOG domain is crucial for the polymerase activity of MOR1

「看護の将来を考える会」の活動報告

紀要委員会企画Special Articles　看護をとりまく環境の激的な変化に関する情報を得て、看護学部教員の有志が領域を超えて看護の将来について自由に語り合う場として、2017 年12 月から「看護の将来を考える会」の活動を開始した。毎月開催し、2018 年12 月で第11 回を数え、延べ115 人が参加した。活動実績と成果について「看護の将来考える会」の世話人として報告する

特定行為研修における３年間の取り組み

紀要委員会企画Special Articles　2018 年に本学は看護師特定行為研修指定研修機関に指定され、2019 年から研修を開始した。３年間の研修で 14 名の研修生が、総合病院や訪問看護事業所等において適切な医療を提供するために、特定行為を実施する看護師を目指し、指定の講義・演習・実習を履修した。　本報告では、特定行為実施が望まれる社会的背景、医療現場で求められる特定行為、看護師が行う特定行為の意味、そして特定行為研修の今後の発展等について述べる

Safety and Quality in the Agricultural Product Chain in Brazil

An agriculture-intensive country should be aware of natural toxins, including both mycotoxins and cyanotoxins, which are closely associated with the quality of raw materials, for food safety and industry. The major production chains – corn, wheat, beef, and broiler chicken – are the top components of agribusiness, and they should be tracked by reliable and practical tools. The corn chain is of particular concern in food production; intensive controls, multi-year mycotoxin monitoring, and improved harmless/sustainable management methods for uninterrupted farming in the tropic-subtropics are needed to achieve a long-lasting trend. The rapid control of natural toxins (mycotoxin and cyanotoxin) has focused on immunochemical methods developed with highly specific monoclonal antibodies (mAb) matched with chromatographic methods. In parallel, the promising widespread application of non-destructive analytical methods based on NIR (Near Infrared Reflectance) spectroscopy, computer vision and hyperspectral imaging coupled with multivariate analyses have been introduced as an alternative for the prediction of quality and compositional parameters. Rapid quality control and product traceability are discussed, as well as accurate monitoring, which is essential for potentially launching an innovative system for food production in Brazil

Mechanisms of microtubule dynamics regulation by the MICROTUBULE ORGANIZATION 1 protein

The Arabidopsis thaliana MOR1 (MICROTUBULE ORGANIZATION1) protein belongs to the MAP215/Dis1 family of microtubule-associated proteins. The temperature-sensitive mor1 mutants have N-terminal amino acid substitutions, which lead to cortical microtubule disorganization (Whittington et al., 2001). Here I demonstrate by use of live cell imaging and immunolabelling that MOR1 is important for function and organization of all microtubule arrays during cell division and keeps microtubules highly dynamic. Although disruption of mitotic and cytokinetic microtubule arrays is not detected in all dividing mor1-1 cells, quantitative analysis identified distinct defects in preprophase bands, spindles and phragmoplasts. In nearly half of dividing mor1-1 cells, preprophase bands are not detected, and those that do form are often disrupted. mor1-1 spindles and phragmoplasts are short and abnormally organized and persist for longer times than in wild-type, leading to aberrant chromosome arrangements, misaligned cell plates and multinucleate cells. Immunofluorescence indicates that the mutant mor1-1[sup L174F] protein remains associated along the full length of all microtubule arrays, in spite of their disorganization. This suggests the N-terminal region altered by the mor1-1 mutation does not regulate the binding of MOR1 to microtubules, but that it instead plays a role in microtubule dynamics. Microtubule dynamics were therefore measured in living leaf cells expressing three microtubule reporter proteins, GFP-TUA, CMV35S ::GFP-EB1 and Pro [sub EB1] ::EB1-GFP. Dynamics analysis indicates that MOR1 promotes constant and rapid growth and shrinkage and prevents pausing of microtubules. Integrating this new information with previous observations showing that MOR1 and its tobacco homologue MAP200 can bind tubulin oligomers (Twell et al., 2002; Hamada et al., 2004), and that XMAP215 speeds up microtubule growth and shrinkage in 40-60nm increments (Kerssemakers et al., 2006), I postulate that MOR1 might promote microtubule growth and shrinkage by adding and removing tubulin oligomers. Consistent with this idea, the N-terminal region of MOR1 consists of 5 TOG domains, which each span the approximate length of one tubulin dimer within a protofilament chain. I define experiments and present preliminary data to test the hypothesis that each MOR1 protein can add or remove up to 5 tubulin dimers at a time.Science, Faculty ofBotany, Department ofGraduat