山丘区土壤环境因子对钉螺(Oncomelania Snail)分布的影响

土壤是自然界钉螺孳生繁殖的重要场所,钉螺的分布与土壤环境因子密切相关。对山丘区9种不同土地利用类型土壤环境对钉螺分布影响的研究结果表明：耕地、荒草地、河滩地及灌溉沟渠存在钉螺分布,活螺框出现率的高低顺序为耕地＞河滩地＞灌溉沟渠＞荒草地,活螺密度的大小顺序为河滩地＞灌溉沟渠＞耕地＞荒草地;有螺土壤环境与无螺土壤环境的方差分析结果不显著,土壤全K含量与0.02~0.002mm的土壤颗粒含量存在显著差异;土壤环境因子对钉螺分布影响的灰色关联分析表明,0.02~0.002mm的土壤颗粒、土壤全P含量和土壤水分是影响钉螺的最重要的3个因子,且土壤环境因子对钉螺活螺框出现率及活螺密度影响的大小规律基本一致,不同之处在于土壤全K含量对活螺密度的影响更显著。研究结果可为我国山丘区改造钉螺孳生环境、控制血吸虫病流行及发展区域经济提供依据     

山丘区土壤环境因子对钉螺 (Oncomelania Snail)分布的影响

土壤是自然界钉螺孳生繁殖的重要场所,钉螺的分布与土壤环境因子密切相关。对山丘区9种不同土地利用类型土壤环境对钉螺分布影响的研究结果表明：耕地、荒草地、河滩地及灌溉沟渠存在钉螺分布,活螺框出现率的高低顺序为耕地〉河滩地〉灌溉沟渠〉荒草地,活螺密度的大小顺序为河滩地〉灌溉沟渠〉耕地〉荒草地;有螺土壤环境与无螺土壤环境的方差分析结果不显著,土壤全K含量与0.02-0.002mm的土壤颗粒含量存在显著差异;土壤环境因子对钉螺分布影响的灰色关联分析表明,0.02-0.002mm的土壤颗粒、土壤全P含量和土壤水分是影响钉螺的最重要的3个因子,且土壤环境因子对钉螺活螺框出现率及活螺密度影响的大小规律基本一致,不同之处在于土壤全K含量对活螺密度的影响更显著。研究结果可为我国山丘区改造钉螺孳生环境、控制血吸虫病流行及发展区域经济提供依据。     

钉螺分布与滩地环境因子的关系

长江中下游滩地钉螺的分布与滩地的地下水位关系显著,当地下水位为３２ｃｍ左右时,钉螺密度和有螺框出现率分别达到其最大值。活螺密度（Ｙ）与地下水位的回归方程为：Ｙ＝－１．９６８６＋０．２５１２Ｘ－０．００４０１３Ｘ＾２;有螺框出现率（Ｙ）与地下水位的关系为：Ｙ＝－５５．９７２０＋７．５６８９Ｘ＝－０．１１８０Ｘ＾２;５月份钉螺适宜在土壤含水率３０％左右的土壤表层生活。当土壤含水率为２８－３０％时,滩面     

淤沙对消灭草滩钉螺作用的观察

监利县中洲与芦苇相连的草滩,1973年水涨前调查,都有钉螺分布,活螺框和活螺密度较其它几种类型都高。通过1973年洪水期淹水130—150天以后调查,钉螺面积和密度发生了显著变化。分析其原因,发现主要是淤沙的作用。为了进一步观察淤沙对草滩钉螺的灭螺作用,于1974年水涨前,从江边直开一条大沟通实验地——大坦(内湖),在大坦边的草滩投放染色螺作实验观察。现将结果报告如下。     

湖区草洲钉螺分布类型的研究

钉螺分布规律的探索是钉螺生态学研究的一项基本课题,从而可进行较为精密的钉螺动态研究,了解环境变化对钉螺消长的影响,以及考核灭螺措施的效果等。1958年Pesigan等在菲律宾的观察认为钉螺分布是符合负二项分布的;苏德隆(1963)据我国水网地区钉螺资料分析,也得出了负二项分布的结论;郁维等(1963)对河岸钉螺分布调查结果,也认为大多数符合负二项分布。但对湖区草洲钉螺分布类型尚缺乏研究,故于江西省鄱阳湖属于星子县的六块草洲进行调查,探求其分布类型,以供研究草洲钉螺动态变化的参考。     

夹竹桃强心总甙灭螺活性与机理

血吸虫病（Schistosomiasis）是严重危害人民身体健康的疾病.钉螺是血吸虫的唯一中间寄主,是血吸虫生活周期中最脆弱环节,灭螺能有效控制血吸虫病,保护湿地和水资源.按强心总甙提取方法,用有机溶剂提取,从118.1940g（相当于100g干材料）夹竹桃新鲜叶中得到0.9815g夹竹桃强心总甙.将强心总甙按5、10、15、20、25、30mg/L配制成6个不同浓度梯度的处理溶液处理钉螺.取活钉螺100只为1组,每20个装入一个尼龙网袋中,分别将各组（5袋/组;网孔2mm）钉螺浸入盛有2000g不同浓度的夹竹桃强心总甙灭螺剂水溶液的玻璃缸中,设1mg/L氯硝柳胺水溶液和无氯清水对照.分别于处理1、2、3、4、5d后,将各处理中的钉螺随机取出1袋,用无氯水冲洗数次,再放入清水中静置1d,然后作存活检查：在解剖镜下针刺无反应的证实死亡.结果显示夹竹桃强心总甙具有很好的毒杀钉螺活性,用20mg/L的夹竹桃强心总甙的水溶液处理3～4d的效果与1mg/L氯硝柳胺溶液处理2～3d的灭螺效果相当;经统计分析：用其水溶液灭螺的.LD50和LD90浓度分别是4.0500mg/L和22.2500mg/L.用LD50浓度的夹竹桃强心总甙溶液处理50个钉螺之后,取活螺用聚丙烯酰胺凝胶电泳（PAGE）进行测试,在处理6h时,显示各处理样品的酶活高于对照组,表现为酶带颜色加深,有新的酶带出现;而在处理12h和24h后,各处理的样品酶带浅于对照组,酶带颜色逐渐变浅,直到消失.采用蒽酮显色法测定经夹竹桃强心总甙处理后钉螺软体的糖原含量糖原含量显著下降,减少幅度从9.9%到32.6%;钉螺经夹竹桃强心总甙处理后蛋白质含量的变化不明显.分析了强化感作用植物夹竹桃植物新鲜叶中强心总甙的灭螺活性,并在微观领域探究其化感作用导致钉螺的形态病理以及糖代谢、蛋白质代谢等生理变化等方面所表现出的杀伤钉螺的机理,由此获得强化感作用植物夹竹桃灭螺的化学生态学证据,为研制新的具中国特色的植物成份灭螺剂打下了基础,并为合成仿生灭螺剂以及最终构建生态工程中强化感作用植物群落灭螺提供理论依据.     

益母草不同组分的抑螺效果及对钉螺酯酶同工酶的影响

通过水浸液灭螺实验,对益母草的根、茎、叶水浸液及益母草水苏碱水溶液的杀灭钉螺作用进行了初步研究.结果表明:各处理均有较好的灭螺效果,但毒效较氯硝柳胺略慢,益母草各部分灭螺效果的顺序为叶＞茎＞根;采用同工酶电泳技术检测了益母草水浸液处理钉螺时对钉螺酯酶同工酶的影响,处理1～2 d后样品的酶活高于对照组,处理3～4 d后的酶活则大大减弱,在这一过程中,有时出现新的酶带,有时又有酶带消失,酶带的变化主要在正极区,与正常的病理反应完全一致.     

樟树水浸液对钉螺的生态毒理学效应

用樟树(Cinnamomum camphora)新鲜根皮、茎皮、叶为材料,设置1%、0.5%、0.1%、0.05%4个不同浓度梯度的水浸液处理钉螺,以清水和1 mg/L浓度的氯硝柳胺溶液为对照,统计钉螺死亡率,并分析钉螺过氧化氢酶(CAT)和过氧化物酶(POD)活性及采用透射电镜分析亚显微结构损伤情况。结果表明:(1)樟树各部分的水浸液均有很好的灭螺效果。钉螺死亡率随处理浓度的增加和时间的延长呈上升趋势,0.5%—1.0%以上的樟树根皮、茎皮、叶水浸液均可达到100%的毒杀钉螺致死效果,与1 mg/L氯硝柳胺溶液的灭螺效果相当;灭螺效果顺序依次为:根皮茎皮叶。(2)在处理初期,钉螺体内过氧化氢酶和过氧化物酶活性明显增强,但随处理时间延长,其活性急剧降低;过氧化物酶同工酶谱显示,处理24—48 h后钉螺酶活高于对照组,处理72—96 h后酶活最强,而处理120 h酶活则大大减弱。(3)钉螺肝细胞亚显微结构观察表明,随处理时间的延长,线粒体、内质网、细胞核等结构损伤越来越严重。这些结果表明樟树水浸液对钉螺肝脏造成过氧化伤害和细胞器结构损伤,具有很好的杀螺效果,可作为生态工程抑螺林树种。     

林农复合系统灭螺机制及其持续灭螺

本文利用连续数年在试验基地观测和调查资料,结合五省其它试验点的研究结果,探讨了林农复合系统灭螺机制及其持续灭螺方法．结果显示,林农复合系统的小气候特征、土壤环境以及实施的耕翻间种措施等不利于系统内钉螺的孳生,使钉螺体内糖原含量明显减少,SDH、LDH活性下降,蛋白质总量和氨基酸含量降低,影响了钉螺的生存和繁殖．林农复合系统动态生长以及汛期外系统钉螺随水而来会影响灭螺．采用间伐、邻近草滩发展水产养殖以及在更大范围建立林农复合系统可以持续灭螺．     

山区埝沟钉螺生态研究初报

为研究山区的灭螺对策,于1982年6月至1983年5月在新华公社进行了钉螺生态观察。新华公社位于邛崃山脉与二郎山交汇处,钉螺分布在海拔700至1000米之间。在该社选择海拔800米处环山灌溉埝一条,长100米,宽、高各1米,泥质,杂草每平方市尺约10棵,土表钉螺每平方市尺50只以上,作为观察现场。每月中旬定时在现场随机分设10框捕捉土表钉螺,并分层(土内一层1—3公分,二层4—6公分)土淘取钉螺和螺卵。观测记录螺旋数,死亡数,雌雄数和感染螺数,选择泥皮完整的螺卵进行孵化,计算孵出数。每月解剖土表雌、雄成螺各10只,测量卵巢、睾丸大小。结果如下:一…     

几种杀螺细菌的筛选与功效研究

湖北钉螺是日本血吸虫的唯一中间宿主,生物杀螺具有环保、成本较低以及对钉螺定向特异的优点。从鄱阳湖草洲土壤及病螺体内分离出4株对钉螺具有高毒性作用的细菌。革兰氏染色和显微镜观察表明,一株为芽孢杆菌,其余3株均为革兰氏阴性杆菌。16srDNA扩增及序列比对鉴定其种属类型,结果显示分别为Enterobactersp．、B．cereus、S．putrefaciens和Aeromonassp．。杀螺研究结果表明,4株细菌的发酵液、发酵上清液和菌体对钉螺均表现出不同程度的毒杀作用,其中S．putrefaciens和Aeromonassp．的杀螺效果最好,72h发酵液和发酵上清液对钉螺的毒杀作用分别达100％和95％以上。各细菌发酵上清SDS-PAGE结果发现了丰富蛋白带,推测这些蛋白中存在对钉螺具有毒杀功效的组分。     

Transplantation of Schistosoma japonicum daughter sporocysts in Oncomelania hupensis

Schistosoma japonicum daughter sporocysts obtained from infected Oncomelania hupensis hupensis were successfully transplanted to parasite-free O. hupensis hupensis. Survival and infection rates of recipient snails were 80% and 75% respectively. Intramolluscan development of transplanted daughter sporocysts in recipient snails appears to proceed in a similar manner as those reported for transplanted S. mansoni and S. haematobium in their respective snail intermediate hosts. Complete colonization of the digestive gland of recipient snails by sporocysts was observed 80 days after transplantation. Cercarial production during a 10-day observation from recipient snails was characterized by periods of high and low and irregular daily emissions. The average daily cercarial production was 150 per snail. Cercariae produced by recipient snails were infective to mice. Of those cercariae exposed to mice, approximately 30% developed to adult schistosomes. These results have definitive utility in the maintenance of S. japonicum in the laboratory.     

冬季水淹对洲滩钉螺生存繁殖影响的观察

在我国长江下游江边，采用现实验性水淹的方法，观察冬季水淹对钉螺生存影响及水淹后尚存活螺繁殖力变化。结果水淹３０、６０、９０、１２０天１５０天后其亡率依次为１．２５％、９．３０％、１９．２３％、３６．０５％和３６．７０％。经水淹６０－９０天，螺的产卵量减少１／２以上，所产卵的孵化率下降约１／３。观察提示，冬季持续一定时间水淹一定时间水淹对湖沼地区钉螺生存和繁殖均为不利。     

Demonstration of replication of daughter sporocysts in the natural development of Schistosoma japonicum

The participation of replicating sporocysts in the intramolluscal development of Schistosoma japonicum within its snail host Oncomelania hupensis is demonstrated by histological studies. Replicating sporocysts were observed in snails maintained under both standard and hibernation conditions. The demographic and epidemiological importance of the replication process within schistosomes is discussed comparatively.     

氚—烟酰苯胺在钉螺体内分布示踪的研究

本文应用氚－烟酰苯胺标记湖北钉螺，示踪观察不同时间烟酰苯胺进入螺体组织和脏器内的分布和进入途径。结果显示，钉螺接触药物从２２分钟开始检测出组织、脏器内氚含量，以后逐渐增高，至１４４０分钟达最高峰；合计不同时间各组织和脏器中药物含量由高至低排列次序为外套膜、胃肠、肝脏、肠内粪梗、睾丸、卵巢、鳃、神经节、心脏；转换氚含量为烟酰苯胺剂量，证实了烟酰苯胺杀螺的低用量与高效性；由单位重量组织和脏器中药物含量排位，反映出药物在螺体分布动态变化，以及药物通过消化系统、呼吸系统、外套膜表皮三条途径进入。     

江滩与兴林垦种林区钉螺氨基酸,总蛋白和糖原含量的比较

测定了兴林垦种林区钉螺和滩地钉螺的总蛋白、氨基酸和糖原含量,结果表明,林地钉螺体同总蛋白含量和１５种氨基酸含量显著下降,尤以雌体降幅较大,达３０％,长江退水２个月后,林地钉螺体内糖原含量开始下降,退水７个月后,其含量较低了３８％。     

Effect of floods on the transmission of schistosomiasis in the Yangtze River valley, People's Republic of China

The aim of the present study was to assess the effect of floods on the transmission of schistosomiasis in the Yangtze River valley, People's Republic of China. Retrospective analyses of malacologic, clinical and epidemiologic data, covering a 22-year period, were carried out to elucidate the dispersal patterns of intermediate host snails (Oncomelania hupensis), and acute and chronic infections with Schistosoma japonicum in humans in relation to floods. Potential O. hupensis habitats in years with floods were 2.6-2.7 times larger than in years when water levels were normal. Both the density and infection rate of O. hupensis dropped in the first two years after a flood, but significantly increased in the third year. The number of acute cases with schistosomiasis japonica was markedly higher in years characterized by floods; on average, 2.8 times more cases were observed when compared to years that the Yangtze River had normal water levels. In view of our findings, emergency responses are warranted as soon as possible after the occurrence of a flood in order to avoid or mitigate the reemergence and spread of human schistosomiasis in the People's Republic of China.     

Three Gorges Dam: Impact of Water Level Changes on the Density of Schistosome-Transmitting Snail Oncomelania hupensis in Dongting Lake Area,China

BackgroundSchistosomiasis remains an important public health issue in China and worldwide. Oncomelania hupensis is the unique intermediate host of schistosoma japonicum, and its change influences the distribution of S. japonica. The Three Gorges Dam (TGD) has substantially changed the ecology and environment in the Dongting Lake region. This study investigated the impact of water level and elevation on the survival and habitat of the snails.MethodsData were collected for 16 bottomlands around 4 hydrological stations, which included water, density of living snails (form the Anxiang Station for Schistosomiasis Control) and elevation (from Google Earth). Based on the elevation, sixteen bottomlands were divided into 3 groups. ARIMA models were built to predict the density of living snails in different elevation areas.ResultsBefore closure of TGD, 7 out of 9 years had a water level beyond the warning level at least once at Anxiang hydrological station, compared with only 3 out of 10 years after closure of TGD. There were two severe droughts that happened in 2006 and 2011, with much fewer number of flooding per year compared with other study years. Overall, there was a correlation between water level changing and density of living snails variation in all the elevations areas. The density of living snails in all elevations areas was decreasing after the TGD was built. The relationship between number of flooding per year and the density of living snails was more pronounced in the medium and high elevation areas; the density of living snails kept decreasing from 2003 to 2014. In low elevation area however, the density of living snails decreased after 2003 first and turned to increase after 2011. Our ARIMA prediction models indicated that the snails would not disappear in the Dongting Lake region in the next 7 years. In the low elevation area, the density of living snails would increase slightly, and then stabilize after the year 2017. In the medium elevation region, the change of the density of living snails would be more obvious and would increase till the year 2020. In the high elevation area, the density of living snails would remain stable after the year 2015.ConclusionThe TGD influenced water levels and reduced the risk of flooding and the density of living snails in the study region. Based on our prediction models, the density of living snails in all elevations tends to be stabilized. Control of S. japonica would continue to be an important task in the study area in the coming decade.     

钉螺神经系统的显微解剖

作者于1988至1990年,对采自南京的133号日本血吸虫的中间宿主钉螺的神经系统进行了显微解剖研究。其神经系统由神经中枢和外周神经组成。前者由8对和两个不成对的神经节组成,神经节之间存在着3种联合和7种连索;后者主要由47对和18条不对称的神经组成;嗅检器位于鳃的基部。