Biology subjects

Higashimura, Y.

Publications and source records attributed to Higashimura, Y..

3 recordsLinked to original sources

bioRxiv2020

Red-beet betalain pigments inhibit amyloid-beta aggregation and prevent the progression of Alzheimer's disease in a Caenorhabditis elegans model

BACKGROUNDBetalain pigments are mainly produced by plants in the order Caryophyllales. Recent interest in the biological functions of betalain pigments has increased with antioxidant, anti-inflammatory, and anticancer activities reported. RESULTSWe investigated the effects of betalain pigments derived from red-beet on amyloid-{beta} (A{beta}) aggregation, a cause of Alzheimers disease. Inhibition of A{beta} aggregation against A{beta}40 and A{beta}42 by betalain pigments in vitro was demonstrated by the Thioflavin T fluorescence assay, circular dichroism spectroscopy analysis and transmission electron microscopic observations. Moreover, we examined the ability of betalain pigments to interfere with A{beta} toxicity by using the transgenic Caenorhabditis elegans strain CL2006, which expresses the human A{beta}42 protein intracellularly within the body wall muscle and responds to A{beta}-toxicity with paralysis. Treatment with 50 M betalain pigments significantly delayed the paralysis of Caenorhabditis elegans. CONCLUSIONThese results suggest that betalain pigments reduce A{beta}-induced toxicity by inhibiting A{beta} aggregation and may lead to their use as inhibitors of A{beta} aggregation.

pharmacology and toxicology↗

bioRxiv2020

Production of ORF8 protein from SARS-CoV-2 using an inducible virus-mediated expression-system in suspension-cultured tobacco BY-2 cells

COVID-19, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which spread worldwide in 2020, is an urgent problem to be overcome. The ORF8 of SARS-CoV-2 has been suggested to be associated with the symptoms of COVID-19, according to reports of clinical studies. However, little is known about the function of ORF8. As one of the ways to advance the functional analysis of ORF8, mass production of ORF8 with the correct three-dimensional structure is necessary. In this study, we attempted to produce ORF8 protein by chemically inducible protein production system using tobacco BY-2 cells. An ORF8-producing line was generated by the Agrobacterium method. As a result, the production of ORF8 of 8.8 {+/-} 1.4 mg/L of culture medium was confirmed. SDS-PAGE and nuclear magnetic resonance (NMR) analysis confirmed that the ORF8 produced by this system is a dimeric form with a single structure, unlike that produced in Escherichia coli. Furthermore, it was suggested that the ORF8 produced by this system was glycosylated. Through this study, we succeeded in producing ORF8 folded into a single structure in a chemically inducible protein production system using tobacco BY-2 cells. It is expected that the functional analysis of ORF8 will be advanced using the ORF8 produced by this system and that it will greatly contribute to the development of antibodies and therapeutic agents targeting ORF8.

plant biology↗

bioRxiv2020

A universal subcuticular bacterial symbiont of a coral predator, the crown-of-thorns starfish

BackgroundPopulation outbreaks of the crown-of-thorns starfish (Acanthaster planci sensu lato; COTS), a primary predator of reef-building corals in the Indo-Pacific Ocean, are major concerns in coral reef management. While biological and ecological knowledge of COTS has been accumulating since the 1960s, little is known about its associated bacteria. The aim of this study was to provide fundamental information on dominant COTS-associated bacteria through a multifaceted molecular approach. MethodsA total of 205 COTS individuals from 17 locations throughout the Indo-Pacific Ocean were examined for the presence of COTS-associated bacteria. We conducted 16S rRNA metabarcoding of COTS to determine the bacterial profiles of different parts of the body, and generated a full-length 16S rRNA gene sequence from a single dominant bacterium, which we designated COTS27. We performed phylogenetic analysis to determine the taxonomy, screening of COTS27 across the Indo-Pacific, FISH to visualize it within the COTS tissues, and reconstruction of the chromosome from the hologenome sequence data. ResultsWe discovered that a single bacterium exists at high densities in the subcuticular space in COTS forming a biofilm-like structure between the cuticle and the epidermis. COTS27 belongs to a clade that presumably represents a distinct order (so-called marine spirochetes) in the phylum Spirochaetes and is universally present in COTS throughout the Indo-Pacific Ocean. The reconstructed genome of COTS27 includes some genetic traits that are probably linked to adaptation to marine environments and evolution as an extracellular endosymbiont in subcuticular spaces. ConclusionsCOTS27 can be found in three allopatrically speciated COTS species, ranging from northern Red Sea to the Pacific, implying that symbiotic relationship arose before the speciation (approximately 2 million years ago). The universal association of COTS27 with COTS and nearly mono-specific association at least with the Indo-Pacific COTS potentially provides a useful model system for studying symbiont-host interactions in marine invertebrates.

microbiology↗