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Fibroblast growth factor (FGF) signaling has been implicated in the regulation of osteogenesis in both intramembranous and endochondral ossifications. In the developing palate, the anterior bony palate forms by direct differentiation of cranial neural crest (CNC)-derived mesenchymal cells, but the signals that regulate the osteogenic cell fate in the developing palate remain unclear. In the present study, we investigated the potential role of FGF signaling in osteogenic fate determination of the palatal mesenchymal cells. We showed that locally activated FGF8 signaling in the anterior palate using a Shox2 knock-in allele and an R26R allele leads to a unique palatal defect: a complete loss of the palatine process of the maxilla as well as formation of ectopic cartilaginous tissues in the anterior palate. This aberrant developmental process was accompanied by a significantly elevated level of cell proliferation, which contributes to an abnormally thickened palatal tissue, where the palatine process of the maxilla would normally form, and by a complete inhibition of Osterix expression, which accounts for the lack of bone formation. The coexpression of Runx2 initially with Sox9 and subsequently with Col II in the ectopic cartilaginous tissues indicates a conversion of osteogenic fate to a chondrogenic one. Consistent with the unique palatal phenotype, RNA-Sequencing analysis revealed that the augmented FGF8 signaling downregulated genes involved in ossification, biomineral tissue development, and bone mineralization but upregulated genes involved in cell proliferation, cartilage development, and cell fate commitment, which was further supported by quantitative real-time reverse transcription polymerase chain reaction validation of selected genes. Our results demonstrate that FGF8 signaling functions as a negative regulator of osteogenic fate and is sufficient to convert a subset of CNC cell-derived mesenchymal cells into cartilage in the anterior hard palate, which will have implications in future directed differentiation of CNC-derived precursor cells for clinical application.

Wetlands are important sources of methane emission. Methane anaerobic oxidation, aerobic oxidation and production, and dissolved methane are important process of methane metabolism. We studied methane metabolism and the soil influencing factors. Potential soil methane production, anaerobic oxidation and aerobic oxidation rates, and dissolved methane in soil porewater changed seasonally and the annual average was 21.15.1 μg g-1 d-1 , 11.03.9 μg g-1 d-1 , 20.95.8 μg g-1 d-1 , and 62.920.6 μmol l-1 , respectively. Potential soil methane production and anaerobic and aerobic oxidation were positively correlated among them and with soil pH and negatively correlated with soil redox potential (Eh). Potential soil methane production and aerobic and anaerobic oxidation rates were negatively related to pore soil methane concentration. Thus, the more water saturated the soil (the lower Eh), the higher its capacity to methane production was, but even higher was soil potential capacity to methane oxidation both in the same anaerobic circumstances and when the soil was suddenly submitted to aerobic conditions. All these results suggested a buffer effect in the methane balance in wetland areas, the environmental circumstances favoring methane production are also favorable to methane anaerobic oxidation.

With the rapidly increasing demand of rice globally, there is an urgent need to develop management strategies to improve the yields of rice crops, while at the same time minimize the possible adverse climatic impacts arising from greenhouse gas emissions from paddy fields. In this study, we investigated the influence of amendment application (steel slag and sulfate), rice cultivars (super rice cultivar, Qiuyou 6, and common rice cultivar, Hesheng 10), and cultivation methods (hand cultivation, machine cultivation, throwing cultivation) on rice yield, soil properties, as well as CH 4 and N 2 O emissions in a subtropical paddy field in southeast China. When compared to the controls, mean CH 4 emissions were significantly lower in the steel slag amendment and sulfate amendment plots by 66.1% and 23.1%, respectively, but significantly higher in the machine cultivation plots by 26.6% (P<0.05). On the other hand, we observed significantly higher mean N 2 O emissions from the super rice, machine cultivation, and throwing cultivation plots than those from the controls by 133.4%, 45.8%, and 172.2%, respectively (P<0.05). When taking into the account both CH 4 and N 2 O emissions, the total global warming potential per unit yield was significantly lower in the plots amended with steel slag and sulfate than in the controls. Moreover, we found that steel slag application, machine cultivation and throwing cultivation were able to increase crop yield significantly (P<0.05). Our findings suggest that a combination of steel slag application and modernized cultivation methods, in particular throwing cultivation, would be effective in improving crop yields and mitigating greenhouse gas emissions from the subtropical paddy fields.

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