Biology subjects

Tokunaga, T.

Publications and source records attributed to Tokunaga, T..

3 recordsLinked to original sources

bioRxiv2021

Localization of planteose hydrolysis during seed germination of Orobanche minor

Root parasitic weeds of the Orobanchaceae, such as witchweeds (Striga spp.) and broomrapes (Orobanche and Phelipanche spp.), cause serious losses in agriculture worldwide. No practical method to control these parasitic weeds has been developed to date. Understanding the characteristic physiological processes in the life cycles of root parasitic weeds is particularly important to identify specific targets for growth modulators. In our previous study, planteose metabolism was revealed to be activated soon after the perception of strigolactones in germinating seeds of O. minor. Nojirimycin inhibited planteose metabolism and impeded seed germination of O. minor, indicating that planteose metabolism is a possible target for root parasitic weed control. In the present study, we investigated the distribution of planteose in dry seeds of O. minor by matrix-assisted laser desorption/ionization-mass spectrometry imaging. Planteose was detected in tissues surrounding--but not within--the embryo, supporting its suggested role as a storage carbohydrate. Biochemical assays and molecular characterization of an -galactosidase family member, OmAGAL2, indicated the enzyme is involved in planteose hydrolysis in the apoplast around the embryo after the perception of strigolactones to provide the embryo with essential hexoses for germination. These results indicated that OmAGAL2 is a potential molecular target for root parasitic weed control. HighlightPlanteose accumulated in tissues surrounding the embryo in Orobanche minor dry seeds and was indicated to be hydrolyzed in the apoplast around the embryo by -galactosidase during germination.

plant biology↗

bioRxiv2020

Angiotensin-converting enzyme 2, a SARS-CoV-2 receptor, is upregulated by interleukin-6 via STAT3 signaling in rheumatoid synovium

Detected in December 2019, the coronavirus disease 2019 (COVID-19) has since spread all over the world, resulting in a global pandemic. The disease is caused by severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), and its symptoms usually include cough, fever, and gastrointestinal problems. Although the prevalence of rheumatoid arthritis (RA) is about 1 % of the global population and RA patients naturally have a chance of acquiring COVID-19 in this pandemic, no studies have considered the expression of angiotensin-converting enzyme 2 (ACE2) (a receptor for SARS-CoV-2) in synovial tissues. Our presenting data revealed that ACE2 expression was elevated in active rheumatoid synovium, and siRNA against STAT3 was able to downregulate ACE2 expression, which was in turn induced by IL-6 signaling.

immunology↗

bioRxiv2018

Microbial communities across a hillslope-riparian transect shaped by proximity to the stream, groundwater table, and weathered bedrock

Watersheds are important suppliers of freshwater for human societies. Within mountainous watersheds, microbial communities impact water chemistry and element fluxes as water from precipitation events discharges through soils and underlying weathered rock, yet there is limited information regarding the structure and function of these communities. Within the East River, CO watershed, we conducted a depth-resolved, hillslope to riparian zone transect study to identify factors that control how microorganisms are distributed and their functions. Metagenomic and geochemical analyses indicate that distance from the East River and proximity to groundwater and underlying weathered shale strongly impact microbial community structure and metabolic potential. Riparian zone microbial communities are compositionally distinct from all hillslope communities. Bacteria from phyla lacking isolated representatives consistently increase in abundance with increasing depth, but only in the riparian zone saturated sediments did we find Candidate Phyla Radiation bacteria. Riparian zone microbial communities are functionally differentiated from hillslope communities based on their capacities for carbon and nitrogen fixation and sulfate reduction. Selenium reduction is prominent at depth in weathered shale and saturated riparian zone sediments. We anticipate that the drivers of community composition and metabolic potential identified throughout the studied transect will predict patterns across the larger watershed hillslope system.

microbiology↗