Biology subjects

Kurokawa, S.

Publications and source records attributed to Kurokawa, S..

3 recordsLinked to original sources

bioRxiv2026

Genomic and ecological characterization of unclassified tetraploid Echinochloa plants distributed in northern Japan

Understanding the evolutionary origins of globally noxious weeds provides insights into the genetic background of weediness. Among species of Echinochloa, the hexaploid E. crus-galli was previously thought to have arisen through hybridization and allopolyploidization between tetraploid E. oryzicola and an undiscovered diploid species, although they exhibit marked differences in both ecological and morphological characteristics. Recently, in Japan, unknown tetraploid Echinochloa plants were discovered that exhibit distinct ecological and morphological characteristics from those of E. oryzicola, with some traits showing greater similarity to those of E. crus-galli. In this study, we investigated the relationships between well-known Echinochloa species and these unknown tetraploid plants, hereafter referred to as ''ninja''. Subgenome-based read mapping analysis and phylogenetic analysis revealed that ninja possesses a distinct genomic composition, while showing close relationships to E. oryzicola in both its chloroplast and nuclear genomes. Furthermore, the identification of a very small number of ninja x E. oryzicola hybrids among field-collected individuals suggests that these two species rarely hybridize in the wild. Although ninja and E. oryzicola showed similar genomic compositions, ninja has a broader habitat range, partially overlapping with that of E. oryzicola and extending into areas occupied by E. crus-galli. Our findings indicate the possibility that hexaploid E. crus-galli may have originated from a tetraploid Echinochloa species other than E. oryzicola.

plant biology↗

bioRxiv2023

Evolution of spite versus evolution of altruism through a disbandment mechanism

Altruism and spite are costly to the actor; therefore, from the perspective of natural selection, the existence of them is a mysterious phenomenon and require explanation. If altruistic individuals are more likely to be recipients for altruism than non-altruistic individuals, then altruism can be favored by natural selection. Similarly, if spiteful individuals are less likely to be recipients for spite than non-spiteful individuals, then spite can be favored by natural selection. Spite is altruisms evil twin or ugly sister of altruism. In some mechanisms (e.g. repeated interaction), if altruism is favored by natural selection, then spite is also favored by natural selection. In contrast, there is a situation which facilitates the evolution of altruism but is unlikely to facilitate the evolution of spite. Population structure is one typical example. Here we focus on the mechanism in which individuals choose to keep the interaction or stop the interaction according to the opponents behavior. We, by using evolutionary game theory, investigate the evolution of altruism and the evolution of spite under this mechanism. Our model shows that the evolution of spite is less likely than the evolution of altruism. This main result provides a nice intuition for why altruism is more abundant than spite in general in the real world.

evolutionary biology↗

bioRxiv2020

In vivo recellularization of xenogeneic vascular grafts decellularized with high hydrostatic pressure method in a porcine carotid arterial interpose model

Autologous vascular grafts are widely used in revascularization surgeries for small caliber targets. However, the availability of autologous conduits might be limited due to prior surgeries or the quality of vessels. Xenogeneic decellularized vascular grafts from animals potentially substitute for autologous vascular grafts. Decellularization with high hydrostatic pressure (HHP) is reported to highly preserve extracellular matrix (ECM) which would be feasible for recellularization and vascular remodeling after implantation. In the present study, we conducted xenogeneic implantation of HHP-decellularized bovine vascular grafts from dorsalis pedis arteries to porcine carotid arteries then evaluated graft patency, ECM preservation and recellularization. Surgical procedure not to damage luminal surface of the grafts from drying significantly increased the graft patency at 4 weeks after implantation (P = 0.0079). After the technical improvement, all grafts (N = 5) were patent with mild stenosis due to intimal hyperplasia at 4 weeks after implantation. Neither aneurysmal change nor massive thrombosis was observed even without administration of anticoagulants nor anti-platelet agents. Elastica van Gieson and Sirius-red stainings revealed fair preservation of ECM proteins including elastin and collagen after implantation. Luminal surface of grafts was thoroughly covered with von Willebrand factor-positive endothelium. Scanning electron microscopy on luminal surface of implanted grafts exhibited cobblestone-like endothelial cell layer which is similar to native vascular endothelium. Recellularization of tunica media with alpha-smooth muscle actin-positive smooth muscle cells was partly observed. Thus, we confirmed that HHP-decellularized grafts are feasible for xenogeneic implantation accompanied by recellularization by recipient cells.

bioengineering↗