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Vegetation is a key component of terrestrial ecosystems, and its changes are very sensitive to climate change (CC) and human activities (HA), especially in ecologically fragile areas (EFA). However, the mechanism of relative contribution to vegetation degradation and restoration in EFA under the influence of CC and HA is still unclear. Based on the Carnegie-Ames-Stanford Approach (CASA) model and the Miami model, we estimated three key parameters of vegetation in China’s EFA: actual net primary productivity (ANPP), potential net primary productivity (PNPP), and human activity net primary productivity (HNPP). Using these variables, we quantitatively analyzed the relative contribution of CC and HA to vegetation restoration and degradation from 1982 to 2018 by the residual trend method. The results showed that the area ratio of vegetation restoration in China’s EFA was close to 71.6%, and the total ANPP increased by 174 Tg C, mainly concentrated in the Southwest Karst area and the Loess Plateau, but the Qinghai-Tibet Plateau showing a trend of degradation during 1982 to 2018. The climate background of each region was a key factor that can never be ignored to determine the positive or negative impact of regional CC and HA on vegetation activities. The CC and HA played a positive role in vegetation restoration areas, with a relative contribution of 59.1% and 16.4%, regional warming and humidification caused by the increase of temperature and precipitation was the main factor driving vegetation restoration. In vegetation degradation areas, The HA was the main driving force, especially the relative contribution of the Qinghai-Tibet Plateau, the arid and semi-arid areas and the Loess Plateau, which were as high as 96.8%, 83.3% and 80.2%, respectively. Finally, the annual average temperature (TEMP) and the annual solar radiation (SRAD) were relatively important and sensitive for the CASA model in the input environmental variables. This study provided a way to quantitatively understand the mechanism of climate change and human activities on the dynamic evolution of vegetation in EFA. In the future, the implementation of ecological protection and restoration projects need to fully consider the differences in climate background and strengthen the monitoring of the ecological environment.

Introduction: Olfactory ensheathing cell is a unique kind of glia cells, which can promote axon growth. Little is known about the differences between olfactory mucosa olfactory ensheathing cells and olfactory bulb olfactory ensheathing cells in the capability to promote nerve regeneration. Objective: To study the recovery of the rat facial nerve after olfactory ensheathing cells transplantation, and to compare the differences between the facial nerve regeneration of olfactory mucosa-olfactory ensheathing cells and olfactory bulb olfactory bulb olfactory ensheathing cells transplantation. Methods: Institutional ethical guideline was followed (201510129A). Olfactory mucosa-olfactory ensheathing cells and olfactory bulb olfactory ensheathing cells were cultured and harvested after 7 days in vitro. 36 Sprague Dawley male rats were randomly divided into three different groups depending on the transplanting cells: Group A: olfactory mucosa-olfactory ensheathing cells; Group B: olfactory bulb olfactory ensheathing cells; Group C: DF-12 medium/fetal bovine serum. The main trunk of the facial nerve was transected and both stumps were inserted into a polylactic acid/chitosan conduit, then the transplanted cells were injected into the collagen in the conduits. After 4 and 8 weeks after the transplant, the rats of the three groups were scarified and the facial function score, facial nerve evoked potentials, histology analysis, and fluorescent retrograde tracing were tested and recorded, respectively, to evaluate the facial nerve regeneration and to analysis the differences among the three groups. Results: Olfactory ensheathing cells can promote the facial nerve regeneration. Compared with olfactory bulb olfactory ensheathing cells, olfactory mucosa olfactory ensheathing cells were more effective in promoting facial nerve regeneration, and this difference was more significant 8 weeks after the transplantation than 4 weeks. Conclusion: We discovered that olfactory ensheathing cells with nerve conduit could improve the facial nerve recovery, and the olfactory mucosa olfactory ensheathing cells are more effective for facial nerve regeneration compared with olfactory bulb olfactory ensheathing cells 8 weeks after the transplantation. These results could cast new light in the therapy of facial nerve defect, and furnish the foundation of auto-transplantation of olfactory mucosa olfactory ensheathing cells in periphery nerve injury. Resumo: Introdução: A célula embainhante olfatória é um tipo especial de célula glial que pode promover o crescimento do axônio. Pouco se sabe sobre as diferenças entre as células embainhantes olfatórias da mucosa olfatória e as células embainhantes olfatórias do bulbo olfatório em relação à sua capacidade de promover a regeneração nervosa. Objetivo: Estudar a regeneração do nervo facial de ratos após o transplante de células embainhantes olfatórias e comparar as diferenças entre a regeneração do nervo facial com o transplante de células embainhantes olfatórias da mucosa olfatória e de células embainhantes olfatórias do bulbo olfatório. Método: As recomendações éticas da instituição (201510129A) foram seguidas. Células embainhantes olfatórias da mucosa olfatória e células embainhantes olfatórias do bulbo olfatório foram cultivadas in vitro e coletadas após sete dias. Trinta e seis ratos Sprague Dawley machos foram divididos aleatoriamente em três grupos, dependeu das células transplantadas: Grupo A, células embainhantes olfatórias da mucosa olfatória; Grupo B, células embainhantes olfatórias do bulbo olfatório; Grupo C, meio de DF-12/soro fetal bovino. O tronco principal do nervo facial foi seccionado e ambos os cotos foram inseridos em um conduto de ácido polilático/quitosana; em seguida, as células transplantadas foram injetadas em colágeno nos condutos. Após quatro e oito semanas do transplante, os ratos dos três grupos foram agitados para a obtenção do escore da função facial, potenciais evocados do nervo facial, análise histológica e marcador fluorescente retrógrado, que foram testados e registrados, respectivamente, para avaliar a regeneração do nervo facial e analisar as diferenças entre os três grupos. Resultados: Células embainhantes olfatórias podem promover a regeneração do nervo facial. Em comparação com as células embainhantes olfatórias do bulbo olfatório, as células embainhantes olfatórias da mucosa olfatória foram mais eficazes na promoção da regeneração do nervo facial, e essa diferença foi mais significativa oito semanas após o transplante em comparação com quatro semanas. Conclusão: Verificamos que células embainhantes olfatórias com conduto nervoso podem melhorar a recuperação do nervo facial e as células embainhantes olfatórias da mucosa olfatória são mais eficazes para a regeneração do nervo facial em comparação com as células embainhantes olfatórias do bulbo olfatório oito semanas após o transplante. Esses resultados podem lançar uma nova luz no tratamento de defeitos do nervo facial e fornecer a base do autotransplante de células embainhantes olfatórias da mucosa olfatória em lesões do nervo periférico.