Biology subjects

Hamamoto, S.

Publications and source records attributed to Hamamoto, S..

3 recordsLinked to original sources

bioRxiv2026

Polygenic evolution towards a morning chronotype in modern humans

Chronotype is a behavioural phenotype, and its phenotypic trend is considered to change at higher latitudes. In the current study, we performed a polygenic assessment of chronotype trend using associated single nucleotide polymorphisms identified by a genome wide-association study. We found that the phenotypic trend towards morningness increased drastically during the migration of anatomically modern humans above 20 degrees north. Furthermore, two types of latitudinal selection of morningness alleles contributed to establishing the trend towards the morning chronotype at higher latitudes. We propose that the trend towards morningness is stronger in present-day modern humans living above 20 degrees north than in Neanderthals.

evolutionary biology↗

bioRxiv2022

Quantitative analysis of calcium oxalate monohydrate and dihydrate for elucidating the formation mechanism of calcium oxalate kidney stones

We aimed to identify and quantitatively analyze calcium oxalate (CaOx) kidney stones on the order of micrometers, with a focus on the quantitative identification of calcium oxalate monohydrate (COM) and dihydrate (COD). Fourier Transform Infrared (FTIR) spectroscopy, powder X-ray diffraction (PXRD), and microfocus X-ray CT measurements (micro-CT) were performed, and the results were compared. The extended analysis method of the FTIR spectrum, focusing on the 780 cm-1 peak, made it possible to achieve a reliable analysis of the COM/COD ratio. We succeeded in the quantitative analysis of COM/COD in the region of 50 x 50 m by microscopic FTIR for thin sections of kidney stones, and by the micro-CT for bulk samples. The extended analysis method of the FTIR spectrum focusing on the 780 cm-1 peak was introduced to analyze the COM/COD ratio. The analysis results based on PXRD measurement with micro sampling, microscopic FTIR analysis of a thin section, and micro-CT observation of a bulk sample of a kidney stone showed roughly consistent results, indicating that all methods can be used complementarily. This quantitative analysis method evaluates the detailed CaOx composition on the preserved stone surface and provides information on the stone formation processes and interactions with organic molecules.

biophysics↗

bioRxiv2019

Properties of rhizosphere soil associated with herbaceous plant roots analyzed using small-scale protocols

The rhizosphere, which is the region of soil adjacent to plant roots, is affected by the activities of both plant roots and associated microorganisms which cause changes in soil properties including nutrient mineral composition. Accordingly, the actual availability of plant nutrients may not be the same as that estimated on the basis of bulk soil analysis. However, the extent and manner in which the availability of plant nutrients in bulk and rhizosphere soils differ remain unclear. Therefore, the present study defined the rhizosphere as the soil adhered to plant roots, established a set of small-scale protocols for analyzing the nutrient minerals of small soil samples, and then characterized the rhizosphere soil of sorghum, Sorghum bicolor (L.) Moench. The mineral contents of the bulk and rhizosphere soil differed significantly, with nutrient contents generally greater in the rhizosphere, and particularly remarkable accumulation was observed in regards to ammonium ion and exchangeable potassium concentrations. Such accumulation might be due, in part, to the greater per weight surface areas of rhizosphere soil particles, but other mechanisms, including the accumulation of organic matter, could also be involved.

plant biology↗