Correlation between the gut microbiome and neurodegenerative diseases:a review of metagenomics evidence

A growing body of evidence suggests that the gut microbiota contributes to the development of neurodegenerative diseases via the microbiota-gut-brain axis.As a contributing factor,microbiota dysbiosis always occurs in pathological changes of neurodegenerative diseases,such as Alzheimer’s disease,Parkinson’s disease,and amyotrophic lateral sclerosis.High-throughput sequencing technology has helped to reveal that the bidirectional communication between the central nervous system and the enteric nervous system is facilitated by the microbiota’s diverse microorganisms,and for both neuroimmune and neuroendocrine systems.Here,we summarize the bioinformatics analysis and wet-biology validation for the gut metagenomics in neurodegenerative diseases,with an emphasis on multi-omics studies and the gut virome.The pathogen-associated signaling biomarkers for identifying brain disorders and potential therapeutic targets are also elucidated.Finally,we discuss the role of diet,prebiotics,probiotics,postbiotics and exercise interventions in remodeling the microbiome and reducing the symptoms of neurodegenerative diseases.

Driving factors and the implications of work choices of rural laborers in ecologically vulnerable areas in North China

Using rural survey data for the year 2009,we provide evidence of work choices of rural laborers in ecologically vulnerable areas in North China,and model these choices as a function of characteristics of individuals,households,and land endowments.The findings reveal large differences between males and females,and between non-farm employment and part-time farming engagement Land scarcity is still an important driving factor in non-farming participation of rural laborers in the study area;and in the current case of land productivity and the total amount of land,there are still surplus rural labor forces in the study area.Diversification of livelihood reduces the pressure on land,thus facilitating ecosystem conservation.So,the paper concludes with the argument that establishing coordination mechanisms among non-farm employment of rural laborers,agricultural production,and restoration of ecosystems are essential for mitigating the conflicts of ecological security,agricultural production,and rural development in mis area.

Agricultural land use intensity study in Taibus Banner, and its determinants： a case Inner Mongolia, China

Based on rural household survey data from Taibus Banner, in the Inner Mongolia Autonomous Region, China, this study separately categorizes agricul- tural land use intensity into labor intensity, capital intensity, the intensity of labor-saving inputs, and the intensity of yield-increasing inputs, and then analyzes their determinants at the household level. The findings reveal that within the study area： （1） labor intensity is higher and capital intensity is lower than in the major grain-producing and economically developed areas of eastern and central China; （2） the most widely planted crops are those with the lowest labor intensity （oats） and capital intensity （benne）; （3） there are marked differences in agricultural land use intensity among households; a major factor affecting land use decision-making is the reduced need for labor intensity for those households with high opportunity costs, such as those with income earned from non-farming activities which alleviates financial constraints and allows for increased capital intensity. As a result, these households invest more in labor-saving inputs; （4） households with a larger number of workers will allocate adequate time to manage their land and thus they will not necessarily invest more in labor-saving inputs. Those households with more land to manage tend to adopt an extensive cultivation strategy. Total income has a positive impact on capital intensity and a negative impact on labor intensity. House- holds that derive a higher proportion of their total income through farming are more reliant upon agriculture, which necessitates significant labor and yield-increasing inputs. Finally, the authors contend that policy makers should clearly recognize the impacts of non-farming employment on agricultural land use intensity. In order to ensure long- term food security and sustainable agricultural develop-ment in China, income streams from both farming and non- farming employment should be balanced.

山区土地流转过程中的零租金现象及其解释——基于交易费用的视角

近年来山区土地流转过程中的零租金现象较为普遍,厘清土地零租金流转的规模及其原因对于提高农村土地流转市场的运行效率具有重要价值。在理论解释的基础上,本文基于重庆市永川区、忠县和酉阳县的农户调查数据,从地块尺度测算了土地零租金流转的规模,并构建Logit模型实证检验了交易费用对土地零租金流转的影响。研究表明:案例区零租金转出地块的比例达到78.62%,其中75.47%的地块转给了亲人或熟人;实证模拟显示,事前、事中和事后3类交易费用的存在是土地零租金流转的重要原因,低成本的流转中介组织、第三方协调机构的存在以及签订规范的书面合同均能显著降低土地零租金流转的概率;规模偏小、质量等级较低、灌溉条件较差和地理位置偏远的劣质地块的零租金流转概率普遍较高。目前,山区土地边际化导致的地租下降是零租金现象的根源,而交易费用偏高则是土地零租金流转的重要原因之一。为此,今后应着重降低山区土地流转中面临的各类交易费用,建立以乡镇为网络节点的低成本流转平台,引导双方签订规范的书面合同。同时,还应关注山区耕地撂荒和农户耕地资产贬值等现象。

Geographic concentration and driving forces of agricultural land use in China

Since the 1990s, China has entered the middle phase of urbanization which leads to the existence of significant geographic concentration of agricultural land use. The average value of regional concentration degree of ten representative crops in China was 59.03%, showing a high degree of geographic concentration in farming. Some typical agriculture provinces in farming have arisen. The degree of geographic concentration in farming has been enhanced, with the average degree of regional concentra- tion often crops increasing considerably by 3.83% in 2009 compared to that in 1990 （55.20%）. The spatial growing center of farming was found to move westward and northward during 1990-2009. Meanwhile food production concentrated in the Northeast China and main producing area, and cash crops production concentrated in Northwest China. Off-farm employment of rural labor force, commercialization of agricultural product and regional comparative advantage are the main driving forces of geographic concentration of agricultural land use. Govern- mental policies with regional differences should be considered to promote further development of agriculture.