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Karst landforms are mainly special landscapes formed by carbonate dissolution. They are characterized by calcium abundance, lack of soil resources, and insufficient water resources. The growth and development of vegetation in the karst area is restricted by the bedrock. It is very important to understand the synergistic interaction between vegetation metabolism and geochemistry of carbonate rocks in karst areas to maintain the stability of structure and function of the karst ecosystem. The mechanism and law of interaction between vegetation and rock geochemical background in karst areas from two aspects is expounded in this paper: vegetation community promotes weathering of carbonate rocks and geochemical background restricts vegetation. Through summarizing: ( 1 ) Plants promote the weathering and dissolution of carbonate rocks through physicochemical and biological actions, such as secreting carbonic anhydrase organic matter, improving the water retention performance of rock surface through boring by organisms and accelerating the disintegration of broken rocks through root splitting, thus forming a unique karst geochemical background of drought, high calcium, shallow soil layer and lack of nutrients in the soil layer. (2) With the long-term interaction between plants and the karst environment, plants adapt to environmental stress by adjusting their own structures and physiological functions, and even their unique plant succession rules. The plants that survived eventually evolved into unique karst plants that were drought-resistant, adaptable to high-calcium environments, and able to cope with nutrient deficiencies. Due to the solubility of carbonate rocks, the hydrologic system forms a two-layer spatial structure of surface and underground, which makes it difficult to utilize groundwater resources. As a result, the available water resources of local plants are limited, and are prone to drought stress. The drought resistance of plants adapts to the drought or water shortage environment mainly through physiological and biochemical processes, morphological structure and water use. In the morphological structure of the plant, through the stomatal regulation and the xeric structural characteristics of the leaves, the transpiration water loss of the plant is minimized. Some karst plants can cope with drought stress through physiological and biochemical processes, which can reduce the damage caused by drought stress by increasing the activities of antioxidant enzymes and accumulating osmoregulatory substances through phytochemicals. Karst plants improve water use efficiency and reduce transpiration through different water use methods in the dry season. For example, some plants absorb deep soil, deep bedrock water or groundwater water through developed deep roots, and some plants even use fog water. The adaptability of plants to high calcium is realized through physiological structure and process. In a high calcium environment, karst plants can limit the excess calcium transfer upward by forming calcified roots and keeping the calcium content in plants in a relatively stable state through the regulation of calcium oxalate crystal cells and leaves. Plants can also control the intracellular calcium ion concentration by regulating the calcium pool in vivo and controlling the absorption and transport of calcium. Organic acids and mycorrhiza secreted by roots can help vegetation obtain nutrients in the soil to cope with nutrient deficiency in the soil. The organic acid content secreted by the roots of karst plants is usually higher than that of non - karst plants, and the increase of organic acid content can help plants to absorb trace elements. Arbuscular mycorrhizal fungi (AM) and ectomycorrhizal fungi (ECM) help plants adapt to nutrient deficiency by absorbing mineral nutrients from the soil. (3) The vegetation succession in the karst area is similar to the general stage of vegetation succession in normal landforms, but the vegetation succession in the karst area has the particularity of self - generation. The vegetation succession from the middle to the top of the mountain takes a longer time. Vegetation succession changed physical and chemical properties and soil quality. In the process of succession, soil bulk density gradually decreases, and porosity gradually increases over time. At the same time, soil nutrients accumulate with the positive succession of vegetation. During the positive succession process of karst vegetation, the soil water and fertilizer retention capacity is enhanced, the stability is increased, and the survival probability of species and the species diversity are also increased. The special rock geochemical background in the karst area leads to the obvious changes in the spatial distribution of soil resources. High soil heterogeneity promotes the formation of plant community species diversity. For example, the tropical karst area in Xishuangbanna, Yunnan Province covers an area of 3600km 2, accounting for 19% of the land area. The forest survey results in the karst area show that there are 153 families, 640 genera and 1394 species of vascular plants, accounting for 77. 7% of the total floristic families, 56. 1% of the genera and 37. 9% of the species, respectively. The karst plant community is the result of the long interaction between the plant and the environment, the continuous adaptation to the environment and the growth and reproduction. The karstification of plants, the adaptation mechanism of plants under the typical karst soil environment such as drought, high calcium stress and lack of nutrient elements, as well as the succession characteristics of karst vegetation shown in the adaptation process and the biodiversity of vegetation are a whole interaction. The site growth of vegetation promotes the weathering of carbonate rocks and the formation of soil, creating conditions for their own growth. Meanwhile, soil area and soil thickness are positively correlated with plant diversity. The succession of vegetation changes the physical and chemical properties of soil and improves the quality of soil, and the karstification of carbonate rocks promotes the growth of vegetation. The adaptive mechanism of vegetation affects the distribution and growth of plants and promotes the succession process of plant communities and the formation of plant diversity. Due to the spatial heterogeneity of the karst environment and the diversity of plant habitats, plant diversity in karst areas is manifested as few genera, few species and endemic species. However, the internal relationship between plant diversity and the stability of the community ecosystem, as well as the comparative characteristics with non-karst areas still need to be further studied and explored. [ABSTRACT FROM AUTHOR]

Ecological restoration is an effective measure to mitigate rocky desertification, control water loss, protect the existing forests and increase vegetation coverage. The long-term ecological restoration project is the key to the sustainable development of regional economy and ecology. Chinese governments have implemented a series of the Karst Rocky Desertification Comprehensive Control and Restoration Project in the karst regions of Southwest China since the late 1990s. In order to reveal the effectiveness of the Karst Rocky Desertification Comprehensive Control and Restoration Project implemented in the typical rocky desertification zone in Luxi County of Yunnan Province, we analyzed the spatiotemporal variation of vegetation coverage on the basis of Mann-Kendall mutation test, Theil-Sei trend analysis, and the relationships between remotely sensed vegetation indices named normalized difference vegetation index (NDVI) and climate changes, human activities using multiple regression analysis and residual analysis. For the analysis, the Moderate Resolution Imaging Landsat TM data at a spatial resolution of 30 meters over the period 1986-2016 are considered. The results are as follows: 1) In the past 30 years, the vegetation coverage of Luxi County showed a significantly increasing trend, with a growth rate of 0.43%/10a (P<0.01), a sudden change-point of time appeared in 2001, and the growth rate increased from 0.35%/10a (P>0.1) to 0.63%/10a (P<0.1); 2) The areas with high vegetation coverage primarily distributed in the eastern and western mountain areas of Luxi County, while the low vegetation coverage distributed at the junction of towns in the central and northern areas; 3) In terms of trends, the areas of vegetation coverage showing increasing and decreasing accounted for 85.2% and 14.79% over the period 1986-2016, respectively. Between 1986 and 2000, the areas of vegetation coverage with extremely significantly increase only accounted for 7.71%, scattered in the northern. But the areas of vegetation coverage with extremely significantly increase rose to 21.62% between 2001 and 2016, which was primarily distributed in eastern mountainous areas where the priority was given to implement the Karst Rocky Desertification Comprehensive Control and Restoration Project; 4) Increase in temperature and precipitation had a positive effect on vegetation coverage, and the contribution of temperature (r = 0.45, P<0.05) on vegetation coverage was significantly higher than precipitation (r =0.372, P<0.05). Between 2001 and 2016, human activities played an important role in the improvement of vegetation coverage. The areas that human activities played a positive role in vegetation coverage accounted for 79.6%, and the areas that human activities played a negative role in vegetation coverage only accounted for 20.4%, almost located in the towns. The impact of climate change on vegetation coverage accounted for 39.1%, the impact of human activities accounted for 60.9%; 5) The ecological restoration project farther from the town showed more important role in the improvement of vegetation coverage. The role of human activities in vegetation improvement is significantly stronger than climate changes. Our study suggested that the Karst Rocky Desertification Comprehensive Control and Restoration Project contributed on the improvement of vegetation coverage and was deemed as one of the important driving forces for vegetation increasing between 2001 and 2016. [ABSTRACT FROM AUTHOR]

The contents of Cu and Ni in the topsoil, and the distribution characteristics of Cu and Ni under different parent materials and land use types were analyzed in the karst area in northern Mashan, Guangxi. The background values of Cu and Ni in the topsoil of the study area were 36. 59, 38. 82 mg / kg respectively and there were 48. 17% and 35. 96% of the samples exceeding the background values of Cu and Ni in Mashan. The relationship of Cu content in the soil was grassland>shrubland>dry farm>woodland>paddy field>orchard, and Ni was shrubland>grassland>dry farm>orchard>paddy field>woodland in different land use types. The soil-forming parent material had a significant impact on the content of soil Cu and Ni. The contents of Cu and Ni in the soil developed by carbonate rocks were significantly higher than that of clastic rocks and alluvial deposits. There were local high value regions of Cu and Ni in the area. The high value regions of Cu were mainly located in the west where human activities are single and in the east and northwest where human activities are intensive and diverse, and the distribution was relatively dispersed. The Ni high value regions were mainly located in the west and east, and the distribution was relatively concentrated. The spatial heterogeneity of Cu content is determined by both geological factors and human factors, while the spatial heterogeneity of Ni is basically derived from geological factors. The results show that the Cu and Ni contents of some samples in the study area are high, and geological factors are the main reasons for this phenomenon. The influence of soil parent material and land use on the accumulation of heavy metal elements should be fully considered when the government makes industrial and agricultural guidance planning in the research area. [ABSTRACT FROM AUTHOR]

Objective: To investigate the role and mechanism of miR-96-5p in cerebral ischemia reperfusion injury (CIRI). Methods: Serum mRNA level of miR-96-5p was detected in 36 patients diagnosed with ischemic stroke (IS group) and 30 healthy subjects (Health group) by qRT-PCR. PC12 cells were divided into 5 groups: Control group, NC-ag group, miR-96-5p-ag group, NC-an group, miR-96-5p-an group. PC12 cells were transfected with Lipofectamine 2000. The transfection efficiency was verified by qRT-PCR. PC12 cells were divided into the following 6 groups: Control group, OGD/R group, OGD/R+NC-agomir group, OGD/R+miR-96-5pagomir group, OGD/R+NC-antagomir group, OGD/R+miR-96-5p-antagomir group. PC12 cells were treated with OGD/R and transfected according to the group scheme. PC12 cell viability was detected by MTT and apoptosis was detected by TUNEL. The modified Longa method was used to establish the CIRI model of rats, and the rats were divided into Sham group, CIRI group, CIRI+NC-an group and CIRI+miR-an group. Rats in Sham group and CIRI group were injected normal saline through tail vein. CIRI+NC-an group and CIRI+miR-an group were injected NC-antagomir and miR-96-5p-antagomir, respectively. Then the neurological function score, cerebral infarct volume and apoptosis of brain tissue of rats in each group were detected. The contents of malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in PC12 cells and rat brain were determined according to the kit instructions. levels of miR-96-5p and Forkhead box O1 (FOXO1) mRNA in PC12 cells and rat brain tissues were detected by qRT-PCR, and protein expression levels of FOXO1, Ac-FOXO1, Bax and Bcl-2 were detected by Western blot. Results: Compared with the Health group, the serum miR-96-5p mRNA level in the IS group was significantly increased (P<0.001). Compared with Control group and NC-ag group, the miR-96-5p level in miR-96-5p-ag group was increased, the mRNA and protein expression levels of FOXO1 were decreased, and the acetylation level of FOXO1 was increased (P<0.05). Compared with Control group and NC-an group, the miR-96-5p level in miR-96-5p-an group was decreased, the mRNA and protein expression levels of FOXO1 were increased, and the acetylation level of FOXO1 was decreased (P<0.05). Compared with OGD/R group and OGD/R+NC-an group, the relative cell activity of OGD/R+miR-an group was increased, the positive rate of TUNEL was decreased, the relative expression level of Bax protein was decreased, the relative expression level of Bcl -2 protein was increased, the level of MDA was decreased. SOD and GSH-Px levels were increased, miR-96-5p levels were decreased, FOXO1 mRNA and protein expression levels were increased, and FOXO1 acetylation level was decreased (P<0. 05). Compared with CIRI group and CIRI+NC-an group, the m nerve function score and cerebral infarction volume of CIRI+miR-an group were decreased, the positive rate of TUNEL was decreased, the relative expression level of Bax protein was decreased, the relative expression level of Bcl -2 protein was increased, the level of MDA was decreased. SOD and GSH-Px levels were increased, miR-96-5p levels were decreased, FOXO1 mRNA and protein expression levels were increased, and FOXO1 acetylation level was decreased (P<0. 05). Conclusion: miR-96-5p is up-regulated in the process of CIRI occurrence, and down-regulation of miR-96-5p may alleviate CIRI through negative regulation of FOXO1. [ABSTRACT FROM AUTHOR]

Objective: To explore the mechanism of aspirin inhibiting intracranial aneurysm formation in rats by regulating Hippo pathway. Methods: Forty healthy SD rats were selected and divided into control group (without any treatment), sham operation group (exposing the posterior branches of bilateral renal arteries and left common carotid artery, but without ligation), aneurysm group (perfusing normal saline after ligating the posterior branches of bilateral renal arteries and left common carotid artery) and aspirin group (perfusing aspirin after artery ligation), with 10 rats in each group. Detection of serum inflammatory factors [tumor necrosis factor-α (TNF-α), monocyte chemoattractant protein-1 (MCP-1), interleukin-6 (IL-6), IL-10)] and vascular endothelial injury markers [nitric oxide (NO), endothelin-1 (ET-1), vascular endothelial growth factor (VEGF)] 12 weeks after intragastric administration. After the rats were killed, the aneurysm size, wall thickness ratio, lumen area and thinning length of the middle membrane were detected. The expression of Yes-associated protein (YAP) was detected. Results: 1) There were obvious bulges on the Willis ring in the aneurysm group and aspirin group, and the bulges in the aspirin group were smaller than those in the aneurysm group. The aneurysm size, lumen area and thinning length of middle membrane in aspirin group were smaller than those in aneurysm group, and the wall thickness ratio was greater than that in aneurysm group (P<0.05). (2) The serum levels of TNF-α, MCP-1 and IL-6 of rats in aneurysm group and aspirin group were higher than those in the control group and sham operation group, while the levels of IL-10 were lower than those in the control group and sham operation group (P<0.05); The serum levels of TNF-α, MCP-1 and IL-6 of rats in aspirin group were lower than those in aneurysm group, while the levels of IL-10 were higher than those in aneurysm group (P<0.05). (3) The levels of serum NO, ET-1 and VEGF in aneurysm group and aspirin group were lower than those in control group and sham operation group (P<0.05); The level of serum NO in aspirin group was higher than that in aneurysm group, and the levels of ET-1 and VEGF were higher than that in aneurysm group (P<0.05). (4) The relative absorbance value of YAP protein expression in aneurysm group and aspirin group was significantly higher than that in control group and sham operation group (P<0.05). The relative light absorption value of YAP protein expression in aspirin group was lower than that in aneurysm group (P<0.05). Conclusion: Aspirin can significantly reduce the inflammatory reaction of rats with intracranial aneurysms, improve vascular endothelial function, and inhibit the formation of intracranial aneurysms, which may be related to the regulation of Hippo signal pathway by inhibiting YAP. [ABSTRACT FROM AUTHOR]

[Objective]The magnitude of monthly NDVI and its change over time am important indicators of the contribution of vegetation activity in different months to total annual plant growth. [Method] In the present paper, the international variations of normalized difference vegetation index(NDVI) and their relationships with temperature and precipitation from 7 meteorological stations in Hainan island during 2001 -2014 using time series normalized difference vegetation index(NDVI) imagery composited in M0D1S product MOD13Q1 were analyzed. [Result] (i) Monthly NDVI increased significantly over the period. The mean monthly NDVI reached the maximum value in August, and the mean monthly NDVI value was 0.785. Monthly temperature decreased significantly, while monthly precipitation gradually increased except for August, (ii) Seasonal NDVI values were increased and there was significant in temperature for four seasons; Precipitation had an increasing trend in spring, summer and autumn but slightly decreased in winter with a trend of 0.31mm yr~1. (iii) A positive correlation between NDVI and precipitation was observed for most of months, nevertheless the negative correlation between NDVI and temperature was observed for most of months. (iv) The response of NDVI to variation of temperature was greater than that of precipitation. NDVI response to the variation of precipitation with a lag of 48 days and to the variation of temperature with a significance. The response of temperature and precipitation peaked in autumn, and the lag time was shorter in autumn and winter, while the lag time was longer in summer. (v)There was more response of vegetation NDVI to the variation of temperature in the northern and southern parts of Hainan island, while less in the central part. Hie response of vegetation NDVI to the variation of precipitation gradually increased from the western to the eastern. [ABSTRACT FROM AUTHOR]

Because the karst critical zone is an important part of the Earth Critical Zone system, the vegetation in karst area is an important carbon sink of terrestrial ecosystem, and the aboveground part of the vegetation in the karst area sequestrates carbon through plant growth, the carbon storage in the underground part is also very considerable, the growth of underground biomass and decomposition of litter also increase soil organic carbon and inorganic carbon content. Therefore, vegetation carbon cycle in karst area is one of the hotspots of karst carbon sink research. Based on the reviewing of research literature on carbon sequestration of karst vegetation in the past 40 years, this paper expounds the unique physiological characteristics of karst vegetation in Southwest China, and focuses on the following four aspects; (1) Evaluation of vegetation biomass, productivity and carbon storage in karst area of Southwest China; (2) Temporal and spatial variation patterns of vegetation and carbon source and sink effect in karst area of Southwest China; (3) Special mechanism of vegetation carbon utilization in karst area; (4) Prediction of vegetation carbon cycle model and carbon sink potential in karst area. The problems existing in the current research am put forward, and the future research direction is prospected. It is proposed that the future research should be carried out in the aspects of systematic determination of relevant parameters and mechanism process of vegetation carbon cycle in karst area, fine identification of vegetation landscape types in southwest karst area, quantification of carbon sequestration process, and correction and modification of karst vegetation carbon cycle model. This paper provides a reference for in-depth understanding the temporal and spatial evolution of carbon cycle in karst region and for exploring regional carbon cycle mechanism. [ABSTRACT FROM AUTHOR]

BACKGROUND : It is generally accepted that recalcitrant dissolved organic carbon ( RDOC) concentrations in the ocean are in the region of 42 p,mol/L. However, the concentrations of RDOC in the karst river systems remain unidentified and there is little evidence about these compounds unavailable to microbial degradation. OBJECTIVES: To reveal the existence of RDOC and its concentrations in the karst river systems, by collecting water samples at different depths (0 m, 5 m and 10 m) from three typical sites (city-river section, reservoir area and outflow area) in the dammed Liu River in 2006. METHODS: Water samples (3 L) were pre-filtered in-situ using 3 pan filter membranes, and then filtered through 0. 22 pan pore-size filter membranes. The 0. 22 filters were used for DNA extraction following the manufacturer’s instructions of the Power Water DNA Isolation Kit ( Mobio laboratories, Inc. , Carlsbad, CA, USA). The real-time PCR assay of the 16S rRNA gene, as a marker of phytoplankton - bacteria, was carried out in a volume of 25 μL. The assay mixture contained 12.5 μL Green - 2 - Go qPCR Mastermix (Sangon Biotech Co. , Ltd, China) , 1 μL of primer (10 μmol/μL) , 9. 5 μL of distilled water, and 1 μL of template DNA (at 5 ng/ μL). Thermal cycling conditions for 16S rRNA gene were as follows; an initial cycle of 95Ti for 3 min, 39 cycles of 95 T for 60 s. 56Ti for 60 s. 72CC for 60 s, and 72T for 5 min. The primers for 16S rRNA gene were designed as 338f ( 5' - CCTACGGGAGGCAGCAG - 3') and 518r ( 5' - ATTACCGCGGCTGCTGG - 3'). Thermal cycling, fluorescent data collection, and data analysis were carried out with CFX96 Touch11" Real-time PCR Detection System ( Bio-Rad, USA) according to instruction manual. The filtrates after through 3 p.m filter membranes were transferred to sterile glass bottles. The bottles were incubated in the dark room at 30Ti for 180 days. Dissolved organic carbon ( DOC) concentrations of all water samples were determined at 30 days interval on a total organic carbon analyzer ( Multi N/C 3100) at the Institute of Karst Geology, CAGS. The obtained data were performed for correlation analyses using the Pearson correlation method (one-tailed t test) with significance defined as P <0.05 by using SPSS 13.0 software for Windows XP (IBM. Armonk, NY. USA). RESULTS: The relationship between Ct and log starting concentration is linear (R2 >0.99). The amplification efficiencies are 90% - 105%. 24.63 μmol/L RDOC is stored in the dammed Liu River systems, supporting the hypothesis that they are resistant to microbial degradation and the dilution limits dissolved organic carbon utilization. CONCLUSIONS: These findings demonstrate the mechanism for the long-term storage of RDOC in karst hydrosphere, which has hitherto been largely ignored. The advanced techniques ( Fourier-transform ion cyclotron resonance mass spectrometry) provide new evidence to test the initial hypotheses for existence of RDOC in the deep karst reservoir waters. [ABSTRACT FROM AUTHOR]