神澤 信行

Protein adsorption is essential for determining material biocompatibility and promoting adherent cell growth. In this study, we focused on the a-plane structure of hydroxyapatite (HAp). This a-plane structure closely resembles the crystal plane where apatite is exposed in long bones. We conducted protein adsorption experiments using HAp ceramics with a preferred orientation to a-planes (aHAp), employing bovine serum albumin (BSA), lysozyme, and fetal bovine serum (FBS) as protein models to mimic the in vivo environment. Higher zeta potential and contact angle values were found in aHAp than in HAp ceramics fabricated from commercial HAp powder (iHAp). Bradford-quantified protein adsorption revealed BSA adsorption of 212 ng·mm−2 in aHAp and 28.4 ng mm−2 in iHAp. Furthermore, the Bradford-quantified protein adsorption values for FBS were 2.07 μg mm−2 in aHAp and 1.28 µg mm−2 in iHAp. Two-dimensional electrophoresis (2D-PAGE) showed a higher number of protein-derived major spots in aHAp (37 spots) than in iHAp (12 spots). Mass spectrometry analysis of the resulting 2D-PAGE gels revealed proteins adsorbed on aHAp, including secreted frizzled-related protein 3 and vitamin K epoxide reductase complex 1, which are involved in cellular bone differentiation. Overall, these proteins are expected to promote bone differentiation, representing a characteristic property of aHAp.

Flowering locus T (FT) is known to promote flowering in response to photoperiodic conditions and has recently been shown to contribute to other phenomenon, such as diurnal stomatal movement. In legumes, FTs are classified into three subtypes, though the role of each subtype is not well defined. It has been reported that when FT of Lotus japonicus (LjFT) is heterologously expressed in Arabidopsis, LjFT functions as a mobile florigen to promote flowering, similar to Arabidopsis FT (AtFT). In this study, we expressed AtFT in L. japonicus using the SUC2 promoter and showed that heterologous expression of AtFT was able to promote flowering in the plant. We also showed that AtFT expression does not affect stomatal closing nor nyctinastic leaf movement. These findings contribute to our understanding of flower development and have potential application to breeding or plant biotechnology.