Quantifying the driving force is significant to understand the impact of climate variation and human activities on grassland degradation. In this study, we selected net primary productivity (NPP) as ...an indicator to quantitatively assess the relative roles of climate variation and human activities in China, Mongolia, Pakistan and Uzbekistan from 2000 to 2013. The results showed that 1.9% of grassland areas experienced degradation in Uzbekistan. By contrast, 29.6%, 16%, and 32.5% of grassland areas underwent restoration in China, Mongolia and Pakistan, respectively. Furthermore, 83.9%, 85.1%, 6.7% of restored grassland areas were influenced by climate variation and 65%, 79.1%, 11.6% of degraded areas were affected by human activities in Mongolia, Pakistan and Uzbekistan, respectively. The NPP variation also could be calculated to evaluate the impacts of these factors and results were consistent with the findings based on area. Therefore, climate variation dominated grassland restoration, human activities dominated degradation in Mongolia and Pakistan, and Uzbekistan was just the opposite. In China, 38.5% of the grassland restoration areas was caused by climate variations compared with 38% induced by human activities. On the contrary, 37.4% of grassland degradation was caused by climate variation and 30% resulted from human activities. In addition, the results based on NPP variation revealed that 39.2% of restored grassland areas were influenced by human activities and 38.2% of degraded areas were affected by climate variation. Therefore, climate variation dominated grassland degradation and the driving force of restoration was determined by the effectiveness of environmental protection programs.
•NPP was used to assess the relative role of driving factor in grassland degradation.•Climate variation benefits the restoration, human activities promote degradation.•Contributions of the two factors varied greatly in these four countries.•Environmental protect programs are beneficial to the grassland restoration.
The ecological conditions of urban areas have been deteriorating in some aspects due to population growth and increasing expansion, with significant effects on human health. Impervious surface areas ...are an important indicator of urban ecological environmental change, therefore quickly and accurately estimating impervious surface areas is essential to monitoring the urban dynamics of change and human activities and their effects on urban environmental quality. Currently, few methods that are applied in estimating urban impervious surfaces are capable of providing results quickly and accurately. Accordingly, this study proposes a new index, named the normalized difference impervious index (NDII), based on Landsat TM images, which uses the visible (red, green, and blue) and thermal bands. The index was used to extract the impervious surface areas of Nanjing city, Jiangsu Province, China, and we assume that the average value of five times strict supervised classification is the true value of impervious surfaces. A combination of red and thermal bands extracted the impervious surfaces with a producer's accuracy of 86.9%, a user's accuracy of 84.6%, an overall accuracy of 91.4%, and a kappa coefficient of 0.8. The accuracy is 87.7% validated by high-resolution images. This method can rapidly extract urban impervious surface areas with promising accuracy.
Grassland degradation in the Qinghai–Tibet Plateau (QTP), has attracted considerable concern because of its negative influence on the development of the local economy and the ecological security of ...China. Climate and human activities are considered as the main driving forces of grassland degradation. However, distinguishing their respective contributions to grassland degradation is a challenge. This study used the Carnegie–Ames–Stanford Approach model, which coupling remote sensing (e.g. NDVI, LAI, near and mid-infrared bands) and meteorological data (precipitation, temperature and radiation), was adopted to simulate the actual and potential NPP in the QTP from 2001 to 2013. The difference between potential NPP and actual NPP was used to represent the influence of human activities. Results showed that nearly 38.8% of the total grassland area underwent degradation, whereas 61.2% experienced restoration. Furthermore, 56.7% of the degraded grassland areas were influenced by climate, and 19.9% were affected by human activities. The restored areas induced by human activities, climate variation, and the combination of the two factors accounted for 28.6%, 12.8% and 19.9% with an increases in NPP of 5923.4, 3188.1 and 5959.2GgC, respectively. Therefore, climate was the principal driving force of grassland degradation, whereas human activities were the dominant factor in grassland restoration. Climate and human activities, as the potential driving force in grassland NPP variations, should be fully understood by a long term monitoring and the main causes exploring in its dynamics. In addition, the uncertainty of the driving forces should be clarifying immediately in the future, and provide scientific basis for policies and plans making in grassland management.
•We established eight scenarios to analyzed grassland degradation.•We evaluate the respective contributions of climate change and human activities to grassland dynamics.•We identified where, what driving force and how much grassland was degraded in Qinghai-Tibet Plateau.•Climate variation is the principal driving force of grassland degradation, whereas human activities are the dominant factor in grassland restoration.•Temperature is the dominate factor in climate induced grassland restoration while radiation is more related with the climate induced grassland degradation.
The carbon use efficiency (CUE) of grassland, a ratio of net primary production (NPP) to gross primary productivity (GPP), is an important index representing the capacity of plants to transfer carbon ...from the atmosphere to terrestrial biomass. In this study, we used the Moderate Resolution Imaging Spectroradiometer (MODIS) data to calculate the global grassland CUE, and explore the spatiotemporal dynamic of global grassland CUE from 2000 to 2013 to discuss the response to climate variations. The results showed that the average annual CUE of different grassland types follows an order of: open shrublands > non-woody grasslands > closed shrublands > woody savannas > savannas. The higher grassland CUE mainly occurred in the regions with cold and dry climate. By contrast, the regions with the lower grassland CUE were mostly in warm and wet environments. Moreover, the CUE exhibited a globally positive correlation with precipitation and a negative correlation with temperature. Therefore, the grassland CUE has considerable spatial variation associated with grassland type, geographical location and climate change.
•CUE was used to measure how efficiently a grassland sequesters atmospheric carbon.•The global grassland CUE exhibited a slightly increasing trend from 2000 to 2013.•The highest and lowest average annual CUE was in the open shrublands and savannas.•Increased temperature lowered the grassland CUE, increased precipitation raised CUE.
Grassland degradation in the QinghaiâTibet Plateau (QTP), has attracted considerable concern because of its negative influence on the development of the local economy and the ecological security of ...China. Climate and human activities are considered as the main driving forces of grassland degradation. However, distinguishing their respective contributions to grassland degradation is a challenge. This study used the CarnegieâAmesâStanford Approach model, which coupling remote sensing (e.g. NDVI, LAI, near and mid-infrared bands) and meteorological data (precipitation, temperature and radiation), was adopted to simulate the actual and potential NPP in the QTP from 2001 to 2013. The difference between potential NPP and actual NPP was used to represent the influence of human activities. Results showed that nearly 38.8% of the total grassland area underwent degradation, whereas 61.2% experienced restoration. Furthermore, 56.7% of the degraded grassland areas were influenced by climate, and 19.9% were affected by human activities. The restored areas induced by human activities, climate variation, and the combination of the two factors accounted for 28.6%, 12.8% and 19.9% with an increases in NPP of 5923.4, 3188.1 and 5959.2GgC, respectively. Therefore, climate was the principal driving force of grassland degradation, whereas human activities were the dominant factor in grassland restoration. Climate and human activities, as the potential driving force in grassland NPP variations, should be fully understood by a long term monitoring and the main causes exploring in its dynamics. In addition, the uncertainty of the driving forces should be clarifying immediately in the future, and provide scientific basis for policies and plans making in grassland management.
Abstract
The corpus cavernosum is the most important structure for penile erection, and its dysfunction causes many physiological and psychological problems. However, its cellular heterogeneity and ...signalling networks at the molecular level are poorly understood because of limited access to samples. Here, we profile 64,993 human cavernosal single-cell transcriptomes from three males with normal erection and five organic erectile dysfunction patients. Cell communication analysis reveals that cavernosal fibroblasts are central to the paracrine signalling network and regulate microenvironmental homeostasis. Combining with immunohistochemical staining, we reveal the cellular heterogeneity and describe a detailed spatial distribution map for each fibroblast, smooth muscle and endothelial subcluster in the corpus cavernosum. Furthermore, comparative analysis and related functional experiments identify candidate regulatory signalling pathways in the pathological process. Our study provides an insight into the human corpus cavernosum microenvironment and a reference for potential erectile dysfunction therapies.
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•Composites with excellent photocatalytic performance were synthesized.•Synthesis process sequence has an effect on material morphology and properties.•Sludge-based biochar has ...multiple roles in the complex system.•Application to degrade humic acid provides new ideas for sludge disposal.
CeO2/sludge-based biochar composites were prepared by a combination of carbonization and oxidation and applied to photocatalytic degradation of humic acid reactions. The effects of the preparation process sequence on the products were investigated from the perspectives of microscopic morphology and phase composition. The results showed that when the carbonization temperature was selected as 700 °C and the oxidation temperature was selected as 650 °C, accompanied by a certain holding time, structurally stable composites were obtained. In the composites, the biochar increased the adsorption property of the system, as well as facilitated the improvement of CeO2 photocatalytic activity. The adsorption degradation rates of SICO and SCIO on humic acid after 3 h of illumination were 57.92% and 82.88%, respectively, which were much better than those of pristine CeO2 and pure sludge-based biochar. This study provided new path for the practical application of municipal sludge disposal products.
Genetic causation for the majority of non‐obstructive azoospermia (NOA) remains unclear. Mutations in synaptonemal complex (SC)‐associated genes could cause meiotic arrest and NOA. Previous studies ...showed that heterozygous truncating variants in SYCP2 encoding a protein essential for SC formation, are associated with non‐obstructive azoospermia and severe oligozoospermia. Herein, we showed a homozygous loss‐of‐function variant in SYCP2 (c.2689_2690insT) in an NOA‐affected patient. And this variant was inherited from heterozygous parental carriers by natural reproduction. HE, IF, and meiotic chromosomal spread analyses demonstrated that spermatogenesis was arrested at the zygotene stage in the proband with NOA. Thus, this study revealed that SYCP2 associated with NOA segregates in an autosomal recessive inheritance pattern, rather than an autosomal dominant pattern. Furthermore, our study expanded the knowledge of variants in SYCP2 and provided new insight into understanding the genetic etiology of NOA.
A homozygous frameshift variant in SYCP2 was identified in a Chinese NOA‐affected patient. HE, IF, and meiotic chromosomal spread analyses demonstrated that spermatogenesis was arrested at the zygotene stage in the proband. This study revealed that SYCP2 associated with NOA segregates in an autosomal recessive inheritance pattern.
Primate-specific genes (PSGs) tend to be expressed in the brain and testis. This phenomenon is consistent with brain evolution in primates but is seemingly contradictory to the similarity of ...spermatogenesis among mammals. Here, using whole-exome sequencing, we identified deleterious variants of X-linked SSX1 in six unrelated men with asthenoteratozoospermia. SSX1 is a PSG expressed predominantly in the testis, and the SSX family evolutionarily expanded independently in rodents and primates. As the mouse model could not be used for studying SSX1, we used a non-human primate model and tree shrews, which are phylogenetically similar to primates, to knock down (KD) Ssx1 expression in the testes. Consistent with the phenotype observed in humans, both Ssx1-KD models exhibited a reduced sperm motility and abnormal sperm morphology. Further, RNA sequencing indicated that Ssx1 deficiency influenced multiple biological processes during spermatogenesis. Collectively, our experimental observations in humans and cynomolgus monkey and tree shrew models highlight the crucial role of SSX1 in spermatogenesis. Notably, three of the five couples who underwent intra-cytoplasmic sperm injection treatment achieved a successful pregnancy. This study provides important guidance for genetic counseling and clinical diagnosis and, significantly, describes the approaches for elucidating the functions of testis-enriched PSGs in spermatogenesis.
The importance of primate-specific genes (PSGs) in spermatogenesis is largely unknown. This study identified variants in an X-linked PSG, SSX1, associated with male infertility. By using cynomolgus monkey and tree shrew models, this study provides a powerful experimental system for elucidating the functions of testis-enriched PSGs in spermatogenesis.
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