Biology subjects

Koga, H.

Publications and source records attributed to Koga, H..

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

The molecular framework of heterophylly in Callitriche palustris L. differs from that in other amphibious plants

Heterophylly refers to the development of different leaf forms in a single plant depending on the environmental conditions. It is often observed in amphibious aquatic plants that can grow under aerial and submerged conditions. Although heterophylly is well recognized in aquatic plants, the associated developmental mechanisms and the molecular basis remain unclear. In this study, we analyzed heterophyllous leaf formation in an aquatic plant, Callitriche palustris, to clarify the underlying developmental and molecular mechanisms. Morphological analyses revealed extensive cell elongation and the rearrangement of cortical microtubules in the elongated submerged leaves of C. palustris. Our observations also suggested that gibberellin, ethylene, and abscisic acid regulate the formation of submerged leaves. However, the perturbation of one or more of the hormones was insufficient to induce the formation of submerged leaves under aerial conditions. Finally, we analyzed gene expression changes during aerial and submerged leaf development and narrowed down the candidate genes controlling heterophylly via transcriptomic comparisons, including a comparison with a closely related terrestrial species. We revealed that the molecular mechanism regulating heterophylly in C. palustris is associated with hormonal changes and diverse transcription factor gene expression profiles, suggesting differences from the corresponding mechanisms in previously investigated amphibious plants.

plant biology↗

bioRxiv2020

Oxicam-type NSAIDs enhance Agrobacterium-mediated transformation in plants

Agrobacterium-mediated transformation represents a key innovation for plant breeding and is routinely used in research and applied biology. However, for several species, the efficacy of transformation is limited. In this study, we discovered that oxicam-type nonsteroidal anti-inflammatory drugs (NSAIDs), including tenoxicam (TNX), enhance the efficiency of Agrobacterium-mediated transient transformation in the model species Arabidopsis thaliana via leaf infiltration and can be successfully applied in analyses of the subcellular localisation of fluorescent fusion proteins. TNX acts as an inhibitor of plant immune responses and lacks similar transient transformation efficiency in a dde2/ein2/pad4/sid2 quadruple mutant background, thereby indicating that TNX increases the efficiency of Agrobacterium infection via a transient shutdown of the immune system mediated by jasmonic acid, ethylene, and salicylic acid signalling. In addition, we found that TNX enhances the efficiency of stable transformation in crops of agricultural and economic importance, such as Jatropha and maize, indicating that TNX can enhance the integration of exogenous DNA into the plant genome via an increased introduction of DNA into plant cells. Given that treatment with oxicam compounds is simple, cost effective, and has broad utility, we anticipate that this discovery will contribute to accelerating genome-editing technologies in plants.

plant biology↗