长期培养和宏组学分析揭示了烃污染环境中的甲基营养型产甲烷途径

针对石油烃污染的厌氧环境,利用微生物的代谢作用将石油烃转化为甲烷是一种潜在的生物修复策略。然而,目前对于微生物厌氧烃降解产甲烷的机制尚不清楚。经过十年的持续富集和转接培养,我们获得了一种能够降解正构烷烃(C_(15)~C_(20))并且产甲烷富集培养体系,并且经过转接培养该培养物在甲烷生产的动力学特性方面得到了持续的提高。综合宏基因组和宏转录组的分析结果,发现正构烷烃主要通过Desulfosarcinaceae、Firmicutes和Synergistetes菌通过富马酸加成的方式进行起始活化,然后在Tepidiphilus菌的协同作用下进一步降解。同时,体系中含量较多的Anaerolineaceae菌主要负责死细胞生物质的回收。根据宏转录组学分析结果,甲烷主要通过H2依赖型的甲基营养甲烷途径产生,主要由候选门Verstraetearchaeta内的Methanomethyliaceae通过利用死细胞生物质回收代谢过程中产生的三甲胺来产生甲烷。这些发现表明,依赖H2的甲基营养产甲烷菌以及甲基营养产甲烷菌可能在含石油烃的地下生态系统的碳循环过程中发挥着重要的作用。

Surveillance-based evidence:elimination of schistosomiasis as a public health problem in the Peoples’Republic of China

Background:A steady progress on schistosomiasis control in the Peoples’Republic of China(P.R.China)was achieved and broadened into the twelve-year medium and long term national plan(MLNP)which marled the implementation of an integrated control strategy across all endemic areas in P.R.China in 2004.To understand the endemic trends of schistosomiasis to assess the effectiveness of an integrated strategy,we conducted an analysis of schistosomiasis surveillance data spanned from 2005 to 2015.Methods:The schistosomiasis sentinel surveillance data from sentinel sites were collected and analyzed from 2005 to 2015.In these sentinel sites,residents aged 6 years or above were screened annually by indirect hemagglutination assay(IHA),while only antibody positives were followed by stool examination either Kato-katz method(KK)and/or hatching technique(HT).Domestic animals raised in sentinel sites were examined by HT for confirming the infection of schistosomes.Snail investigation was conducted each year through systematic sampling method combined with environmental sampling method.The snails collected from field were tested by microscopic dissection method.The infection rates of schistosomes in residents,domestic animals and snails,as well as the indicators reflecting the snails’distribution were calculated and analyzed.ANOVA analysis was used to examine the changes of the number of eggs per gram feces in population and Chi-square test was used to examine any change in proportions among groups.Results:A total of 148902 residents from sentinel sites attended this study and 631676 blood samples were examined by IHA test during the 11 covered years.The annual average antibody positive rates presented a significant decrease trends,from 17.48%(95%CI:17.20–17.75%)in 2005 to 5.93%(95%CI:5.71–6.15%)(χ2=8890.47,P<0.001)in 2015.During 2005–2015,the average infection rate of schistosomes in residents declined from 2.07%(95%CI:1.96–2.17%)to 0.13%(95%CI:0.09–0.16%),accompanied by significant decrease of infection intensity in population.In 2015,the stool positives were only found in farmers,fishermen and boatmen with infection rate of 0.16%(95%CI:0.11–0.20%),0.17%(95%CI:0–0.50%)respectively.The infection rate of schistosomes in domestic animals dropped from 9.42%(538/5711,95%CI:8.66–10.18%)to 0.08%(2/2360,95%CI:0–0.20%)from 2005 to 2015.Infections were found in eight species of domestic animals at the beginning of surveillance while only two cattle were infected in 2015.Totally 98 ha of new snail habitats were found,while 94.90%(93/98)distributed in lake and marshland regions.The percentage of frames with snails decreased from 16.96%(56884/335391,95%CI:16.83–17.09%)in 2005 to 4.28%(18121/423755,95%CI:4.22–4.34%)in 2014,with a slightly increase in 2015.Meanwhile,the infection rate of schistosomes in snails was decreased from 0.26%(663/256531,95%CI:0.24–0.28%)to zero during 2005–2015.Conclusions:The infection rate of schistosomes declined significantly,providing evidence that the goal of the MLNP was achieved.Elimination of schistosomiasis as a public health problem defined as WHO was also reached in P.R.China nationwide.Surveillance-response system should be improved and strengthened to realize the final goal of schistosomiasis elimination.

Distribution pattern of the snail intermediate host of schistosomiasis japonica in the Poyang Lake region of China

Background:With the closure of the Three Gorges Dam in 2003 the hydrology of Poyang Lake was altered dramatically leading to significant changes in the environment.In order to assess the impact on schistosomiasis this study assessed the spatial and temporal patterns of the snail intermediate host,Oncomelania hupensis in the Poyang Lake tributaries.The results of the study have important implications for future snail control strategies leading to disease elimination.Methods:The marshland area surrounding Poyang Lake was divided randomly into 200×200 m vector grids using ArcGIS software,and the surveyed grids were randomly selected by the software.The snail survey was conducted in each selected grid using a survey frame of 50×50 m with one sideline of each grid serving as the starting line.No less than ten frames were used in each surveyed grid with Global Positioning System(GPS)recordings for each.All snails in each frame were collected to determine infection status by microscopy.Altitude data for all frames were extracted from a lake bottom topographic map in order to analyze the average altitude.All snail survey data were collected and statistically analyzed with SPSS 20.0 software in order to determine the difference of the percentage of frames with living snails and mean density of living snails in different regions of Poyang Lake.The altitude of the snail-infested marshlands and snail dens were subsequently identified.Results:A total of 1159 potential snail sampling grids were surveyed,of which 15231 frames(0.1 m2/frame)were investigated.1241 frames had live Oncomelania snails corresponding to 8.15%of the total number of frames.The mean density of living snails was 0.463/0.1 m2 with a maximum of 57 snails per frame.The percent of frames with snails in the southern sector(8.13%)of Poyang Lake did not differ statistically from the north(8.21%).However,the mean density of live snails in the northern sector(0.164/0.1 m2)of the lake was statistically higher(F=6.727;P=0.010)than the south(0.141/0.1 m2).In the south of the lake,the elevation of snail-inhabited marshland ranged between 11-16 m,and could be further subdivided into two snail-concentrated belts at 12-13 m of elevation and 15-16 m of elevation respectively.In the north of the lake,the elevation of snail-inhabited marshland ranged between 9-16 m with the elevation of 12-14 m being the snail-concentrated zone.Conclusions:The elevation of snail-infested marshlands in the Poyang Lake region ranged from 9 to 16 m.The snail distribution and habitat has moved north of the lake and to a lower altitude due to changes in the water level post dam closure.Based on the current geological features of the snail habitant focused mollusciciding should occur in snail dense northern regions with frequent bovine and human traffic.Targeting these identified'hotspots'of transmission will assist in elimination efforts.

Impact of continuous low water stage on the breeding environment of Oncomelania hupensis: a case study of Poyang Lake area in China

Background Oncomelania hupensis is the only intermediate host of Schistosoma japonicum and plays a decisive role in its transmission.The variation of water level greatly affects the reproduction and growth of snails.Therefore,in this paper,we analyze the variations of water level in the Poyang Lake region from 1993 to 2016 combined with satellite imagery to elucidate the evolution of the snail breeding environment.Methods By employing remote sensing data from 1993 to 2016(April–June and September–November),the vegetation area of Poyang Lake and the vegetation area at different elevations were extracted and calculated.Moreover,the average daily water level data from the four hydrological stations(Hukou station,Xingzi station,Tangyin station and Kangshan station)which represent the typical state of Poyang Lake were collected from 1993 to 2016.The variance of the monthly mean water level,inundation time and the average area were analyzed by variance to find a significance level ofα=0.05.Results According to hydrological data before and after 2003,the average water level after 2003 is significantly lower than that before 2003 in Poyang Lake.After 2003,the time of inundateing the snail breeding period was later in April to June than that before 2003,while the time of wate-falling stage in September to November moved forward after 2003 than before 2003.Of them,the lowest water level affecting the breeding and growing period of O.hupensis in the northern part of Poyang Lake decreased from 11 m to 9 m.After 2003,the expansion of meadow area in the north part of Poyang Lake was mainly concentrated in the elevation of 9–11 m,and the newly increased infested-meadow in the lake area was mainly concentrated in the north part of Poyang Lake.Conclusions By comparing the change of water level characteristics in different parts of the Poyang Lake area as well as changes in meadow area before and after 2003,it is found that the water level changes mainly affect the snail breeding area in the northern part of Poyang Lake.The results are helpful for improving scientific measures for snail control in Jiangxi Province.This approach could also be applicible to Dongting Lake area and other lake areas affected by water level changes and can bring significant guidance for snail control in lake areas.