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ABSTRACT The growth plate is the primary site of longitudinal bone growth with chondrocytes playing a pivotal role in endochondral bone development. Chondrocytes undergo a series of differentiation steps, resulting in the formation of a unique hierarchical columnar structure comprising round, proliferating, pre‐hypertrophic, and hypertrophic chondrocytes. Pre‐hypertrophic chondrocytes, which exist in the transitional stage between proliferating and hypertrophic stages, are a critical cell population in the growth plate. However, the molecular basis of pre‐hypertrophic chondrocytes remains largely undefined. Here, we employed scRNA‐seq analysis on fluorescently labeled growth plate chondrocytes for their molecular characterization. Serine incorporator 5 (Serinc5) was identified as a marker gene for pre‐hypertrophic chondrocytes. Histological analysis revealed that Serinc5 is specifically expressed in pre‐hypertrophic chondrocytes, overlapping with Indian hedgehog (Ihh). Serinc5 represses cell proliferation and Col2a1 and Acan expression by inhibiting the transcriptional activity of Sox9 in primary chondrocytes. Chromatin profiling using ChIP‐seq and ATAC‐seq revealed an active enhancer of Serinc5 located in intron 1, with its chromatin status progressively activated during chondrocyte differentiation. Collectively, our findings suggest that Serinc5 regulates sequential chondrocyte differentiation from proliferation to hypertrophy by inhibiting Sox9 function in pre‐hypertrophic chondrocytes, providing novel insights into the mechanisms underlying chondrocyte differentiation in growth plates. [ABSTRACT FROM AUTHOR]

Oceanic islands are a major tourist destination, and the invasion of exotic plants on oceanic islands is a serious problem. To discuss how exotic herbaceous plant invasion is driven by human disturbance on an oceanic island, we assessed the distribution patterns of exotic herbaceous species along a metropolitan road, including parking lots, on the island of Chichijima in the Ogasawara Islands of Japan in the North Pacific Ocean. We observed 16 exotic herbaceous species representing seven families, and all the species have also been recorded in surveys 25 years ago. Species richness (number of species per plot) ranged from 0 to 9 with an average of 2.49. Distance from a parking lot was significantly negatively related to the distribution patterns of seven species and positively related to three species, pointing to parking lots being critical nodes along the dispersal pathways of exotic herbaceous species in Chichijima. Although roads are well known to play an important role as corridors for the invasion and seed dispersal of exotic plants, our results suggest that it would also be important to consider the location of parking lots to understand the distribution of exotic herbaceous species in road networks. We suggest that intensive weed management near parking lots and car wash protocols on Chichijima may be effective in halting exotic species spread. [ABSTRACT FROM AUTHOR]

The affinity between carbon nanotubes (CNTs) and organic compounds is of substantial importance since it strongly relates to the dispersibility of CNTs in those compounds. Several affinity evaluation methods have been developed so far, and the concept of the Hansen solubility parameter is a representative method widely used in the field of nanocarbon materials. Here, we demonstrate that CNT-loaded silica columns can effectively assess the affinity of organic compounds for CNT surface by exploiting the chromatographic retention time as a criterion. Obtained trends of the affinity of organic compounds for CNT were compared to those based on Hansen solubility parameter distance values. Most organic compounds showed similar trends, but one exceptional compound was observed. Simple CNT dispersion tests were conducted with these organic compounds to demonstrate the advantage of the chromatographic assessment. Further, we conducted comparison experiments using a pyrene-functionalized column and other CNT-loaded columns to elucidate the characteristics of each CNT column. The chromatographic approaches using CNT columns would be beneficial for realizing CNT suspensions with improved CNT dispersibility. [ABSTRACT FROM AUTHOR]

Following the control of an invasive tree species, native forest ecosystem restoration can be prevented by a secondary invasion by another invasive species that inhibits the reestablishment of native trees. In this study, we evaluated the effects of the invasive shrub Leucaena leucocephala on the initial growth of planted seedlings of four native tree species (Pandanus boninensis, Rhaphiolepis indica, Schima mertensiana, and Terminalia catappa) after eradication of the invasive tree Casuarina equisetifolia in the Ogasawara Islands in the northwestern Pacific Ocean. In a 24‐month field experiment, we compared the sizes of planted seedlings (diameter at ground level, height, and leaf number) among four treatments in a 2 × 2 design of initial seedling size (large vs. small) × L. leucocephala invasion (sowing L. leucocephala seeds vs. control). More than 75% of the seedlings (excluding S. mertensiana) survived regardless of the treatments. For all four species, initially large seedlings tended to become larger plants at the end of the experiment than initially small seedlings. We detected significant effects of L. leucocephala invasion on one or more plant size parameters in all four species. Seedlings grown in L. leucocephala invasion quadrats were smaller than those in control quadrats at the end of the experiment. We detected significant interactions between initial seedling sizes and L. leucocephala invasion for three species. Together, these results indicate that secondary invasion by L. leucocephala after controlling C. equisetifolia inhibits the initial growth of native tree seedlings, depending on their size at the time of invasion. [ABSTRACT FROM AUTHOR]