共查询到20条相似文献，搜索用时 46 毫秒
1.
对宿主来源的寄生原虫直接克隆,为调查自然界寄生原虫克隆的流行病学、生态学、遗传学及其宿主的关系等研究提供更准确的实验材料。为此我们对来源于宿主肠道的熊蜂短膜虫(Crithidiabombi)进行了直接克隆的实验。结果报道如下。 相似文献
2.
【目的】近年来,熊蜂作为温室作物的理想授粉者在国外已被广泛利用,并且获得很好的经济效益和生态效益,所以国外熊蜂经常被进口用于设施农业。熊蜂短膜虫Crithidia bombi是熊蜂的一种重要寄生虫病,一旦随进口熊蜂传入,将给国内熊蜂蜂群带来严重危害,因此迫切需要建立一种熊蜂短膜虫检测方法。【方法】基于熊蜂短膜虫基因内转录间隔区(internal transcribed space,ITS)基因序列设计了一对引物(Cri-F/R),建立了熊蜂短膜虫的PCR检测方法,并对退火温度、引物浓度和循环个数等反应条件进行了优化,同时验证了该PCR方法的灵敏性、特异性和稳定性。【结果】以熊蜂短膜虫ITS基因保守区设计特异性引物建立的熊蜂短膜虫PCR检测方法是可行的。优化的PCR反应条件为:退火温度59℃,引物浓度0.5μmol/L,扩增循环数35次。对感染熊蜂短膜虫的熊蜂总DNA的灵敏度达到13.24×10-5ng/μL,并具有良好的特异性和稳定性。将该方法应用于熊蜂短膜虫的检测,整个检测过程不超过4 h,具有良好的适用性。【结论】研究建立了熊蜂短膜虫检测方法,能用于疫情监测和进境熊蜂的检验检疫。 相似文献
3.
以过冷却点和冰点为评价指标,对短舌熊蜂Bombus terrestris的幼虫,蛹,成年工蜂,成年雄蜂,处女蜂王,越冬后的蜂王及红光熊蜂Bombus ignitus的成年工蜂,成年雄蜂,处女蜂王的耐寒力进行检测。结果显示,短舌熊蜂幼虫期耐寒力最低,其次是蛹,工蜂和雄蜂,处女王较高。耐寒力最高的是越冬后的蜂王,其含水量也最低。将短舌熊蜂与红光熊蜂的成年工蜂,成年雄蜂和处女蜂王三型蜂分别进行对比,结果显示,红光熊蜂成年雄蜂与处女蜂王的耐寒力要比短舌熊蜂高。样本的湿重和含水量与过冷却点和冰点无显著相关性。 相似文献
4.
本文详细描述了广东肝血簇虫(Hepatozoon guangdongensis)在实验宿主、中国水蛇肺部裂体生殖整个发育过程各期虫体的超微结构。成熟裂殖体内的裂殖子与肺部毛细血管内皮细胞内的裂殖子的超微结构是相似的。裂殖子(3.4×1.3μm)外被由外膜和内膜构成的表膜,它与球虫一样具有包括类锥体在内的完全顶复结构。内皮细胞内的裂殖子和滋养体都没有围虫泡和围虫泡膜包绕。具有内膜的长形滋养体变圆,并外被由宿主细胞产生的围虫泡和围虫泡膜包绕,转变成为圆形的幼期裂殖体,然后发育成为成熟的裂殖体。成熟裂殖体(23×10μm)内含30—50个裂殖子。裂殖体内没有观察到残余体存在。 相似文献
5.
【背景】近年来,由于栖息地减少、农药的大量使用及病原菌侵染等综合因素,导致全世界的熊蜂种类与数量逐年减少,病原菌的侵染可通过微生物在自身生长过程中会产生的抑菌物质进行有效抑制或杀灭。【目的】短头熊蜂(Bombus breviceps)长期生存在野外环境中,其肠道内存在着大量微生物资源。从短头熊蜂肠道内筛选拮抗菌株,并对其抑菌特性进行研究。【方法】采用牛津杯双层法筛选拮抗菌株,测定抑菌活性最佳菌株发酵液的抑菌物质稳定性与抑菌广谱性等抑菌特性,并借助细胞膜通透性、流式细胞仪检测等试验探究其抑菌机制。【结果】得到了5株具有明显抑菌作用的拮抗菌株,其中果杆菌(Fructobacillus tropaeoli)CZ01对金黄色葡萄球菌(Staphylococcus aureus)、沙门氏菌(Salmonella choleraesuis)、大肠杆菌(Escherichia coli)、福氏志贺氏菌(Shigella flexneri)和无乳链球菌(Streptococcus agalactiae)这5种病原指示菌都具有高度抑菌效果。菌株CZ01对金黄色葡萄球菌的抑菌效果最佳,抑菌圈直径可达到(21.21±0.25) mm,在121 ℃处理后仍具有67.36%以上的抑菌活性,调整pH值为10.0时仍具有78.16%的抑菌活性。【结论】短头熊蜂肠道微生物资源较丰富,尤其是果杆菌(F.tropaeoli)CZ01具有抑菌活性高、稳定性好、抑菌谱广等特性,对金黄色葡萄球菌具有良好的杀灭效果,显示出良好的应用潜能。 相似文献
6.
陈围;杨承忠;赵元莙 《四川动物》2016,35(2):183-189
: 以18S rDNA为分子标记,对碘泡虫属Myxobolus粘孢子虫的分子进化规律进行了系统研究。结果显示:碘泡虫属各物种18S rDNA的AT含量(53.2%)高于GC含量(46.8%),表现出一定的AT组成偏向性;各物种18S rDNA遗传距离在0.00~0.35;脑碘泡虫M. cerebralis保守区序列变异介于淡水物种和广盐性物种之间;碘泡虫属18S rDNA分子系统发育树呈现生境相同先聚枝,形态相似后聚枝的规律,并表现出一定的宿主特异性和组织向性。此外,以线粒体COⅠ基因为分子标记,对碘泡虫属相应宿主进行了系统进化分析,结果表明:淡水物种与广盐性物种分别聚在不同的分类枝系中,与寄生于宿主体内的碘泡虫所呈现的支序树有相同的进化趋势,并表现出一定的协同进化关系;海水起源的虹鳟Oncorhynchus mykiss在适应淡水过程中被脑碘泡虫寄生,两者经过长期的演化,最终适应淡水环境。 相似文献
7.
隐新棘虫Pallisentis celatus(Van Cleave,1928),隶于四环科(Quadrigyridae)棘衣属Pallisentis。成虫寄生于鳝鱼、鲶鱼、鳗鱼肠内,亦有报道可寄生于泥鳅(Misgurnus anguillicaudatus)、虎蚊蛙等。1986—1989年逐月从市场购买泥鳅进行解剖,均未发现成虫寄生。所获标本均系寄生于泥鳅体腔内的童虫纤维性包囊(图2)。共解剖泥鳅1225条,感染率33.55%,其中以大(体长13厘米以上)、中(体长10—12厘米)型泥鳅为高。感染月份以每年2—3月、7—10月达高峰,为40—51.8%。刺破包囊或用人工消化液消化获得童虫。经观察童虫吻、吻钩数目,形态,大小,体棘… 相似文献
8.
9.
为弄清倒刺鲃两极虫(Myxidium spinibarba)的宿主多样性和胭脂鱼(Myxocyprinus asiaticus)寄生黏孢子虫的种类组成,研究基于形态和分子数据,比较分析了寄生于不同宿主的倒刺鲃两极虫的形态学和形态计量学特征及分子系统发育关系。结果显示:寄生于胭脂鱼和中华倒刺鲃的倒刺鲃两极虫株系在形态学和形态计量学上未出现显著性差异, 18S rDNA序列相似度为99.9%—100.0%,遗传距离为0.000—0.001,符合种内变异;寄生于不同宿主倒刺鲃两极虫的株系在系统发育树中嵌合聚支,且寄生于胭脂鱼的倒刺鲃两极虫株系先分化。以上结果表明:研究中两株系与倒刺鲃两极虫为同一物种,但在分子水平已经出现分化;这是首次在胭脂鱼中检获到黏孢子虫,胭脂鱼是倒刺鲃两极虫的新宿主。 相似文献
10.
【目的】研究不同工业酿酒酵母宿主背景对重组酵母木糖利用效率的影响。【方法】将木糖利用途径的木糖还原酶(XR)、木糖醇脱氢酶(XDH)和木酮糖激酶(XK)编码基因串联后分别转入3株不同的工业酿酒酵母中,得到重组酵母ZQ1、ZQ5和ZQ7。分别对3个木糖途径代谢基因的表达水平、酶活和重组菌株的木糖发酵效率进行比较。【结果】重组菌株在木糖代谢基因转录、酶活性和木糖利用性能方面有很大差异,其中ZQ5木糖代谢能力最强,ZQ7其次,ZQ1木糖利用能力最弱。ZQ7在初始木糖浓度为20 g/L时木糖利用速率快于ZQ5,表明木糖浓度对重组菌发酵性能评价具有影响。【结论】不同菌株的遗传背景和木糖浓度对重组菌木糖利用的影响很大,评价重组酵母的木糖利用需考虑宿主的遗传背景和底物浓度的影响。 相似文献
11.
SANDRA GILLESPIE 《Ecological Entomology》2010,35(6):737-747
1. Bumblebees are important pollinators in North America and are attacked by a range of parasites that impact their fitness; however, few studies have investigated the extent or causes of parasitism in North America. 2. This study used a 2‐year multi‐site survey of bumblebee parasitism to ask: (i) how common are parasitoid conopid flies and the internal parasites Crithidia bombi and Nosema bombi in Massachusetts; and (ii) what factors are correlated with parasitism? 3. Infection rates by all three parasites were higher in this study than previously documented in North America. Overall, conopids infected 0–73% of bees in each sample, C. bombi infected 0–82% of bees, and N. bombi infected 0–32%. 4. Conopid flies infected female bees more than males and intermediate‐sized bees more than large or small bees. Crithidia bombi infection rates were higher in certain bee species and sites, and exhibited a unimodal pattern of prevalence over time. Nosema bombi parasitism was higher in male than female bees. 5. Infection by N. bombi in two rare bumblebee species was higher than expected based on parasitism rates of common bee species but C. bombi infection was lower. If high prevalence of N. bombi in these bumblebee species is common, parasitism may be a potential cause of their decline. 6. Given the documented effects of these parasites, the high levels of infection may affect bee populations in Massachusetts and threaten the stability of their valuable ecosystem services. 相似文献
12.
1. Increasing urbanisation is often cited as a cause of declining biodiversity, but for bumblebees there is evidence that urban populations of some species such as Bombus terrestris L. may be more dense than those found in agricultural landscapes, perhaps because gardens provide plentiful floral resources and nesting opportunities. 2. Here we examine the influence of urbanisation on the prevalence of the main protozoan parasites of bumblebees in west central Scotland. We would expect transmission rates and prevalence of parasites to be higher in high density host populations, all else being equal. 3. Workers of two bee species, B. terrestris and B. pascuorum, were sampled over a 45‐day period in mid to late summer, and parasites were detected in faeces and via dissection. A comparison of the two methods suggests that faecal sampling is considerably less sensitive than dissection, failing to detect infection in 27.8%, 55.1%, and 80% of cases of infection with the parasites Crithidia bombi, Nosema bombi, and Apicystis bombi, respectively. 4. For all three parasites, broad patterns of prevalence were similar, with prevalence tending to increase with urbanisation in B. terrestris but not in B. pascuorum. The different patterns of seasonal prevalence in the two bee species suggest that intraspecific transmission is more important that interspecific transmission. 5. Our observation of greater parasite prevalence among B. terrestris in urban compared with rural areas suggests that urban habitats may present greater opportunities for parasite transmission. Greater bee densities in urban areas may be the driving factor; however, further study is still needed. For example, differences in disease prevalence between habitats could be driven by differences in the types and abundance of flowers that are available, or in exposure to environmental stressors. 相似文献
13.
Most studies of the consequences of parasitism on fitness have examined single host–parasite systems. However, parasitological studies show that most hosts are constantly challenged by a complex parasite community. Thus, neither the response of hosts to individual parasite species nor the individual impact of these parasite species is likely to be as unconstrained as studies of single host–parasite systems might suggest. In this study, the parasite community structure in spring queens of the common European bumble bee, Bombus pratorum, was assessed. By capturing queens and allowing them to rear colonies in the laboratory, the relative impact of different parasite species on fitness across the annual host life-cycle could be examined. Of 160 queens, 67% were parasitised by one or more members of a five-species parasite community. The impact of parasites varied from being highly virulent to undetectable under benign laboratory conditions. The majority of multi-parasite infections involved a high impact parasite, which resulted in the removal of associated parasites from the host population. This study shows that, whilst multiple infections occur within individual hosts, most parasites act individually on their hosts. However, multiple parasite species in the host population may constrain the host population’s ability to adapt to single parasite species. 相似文献
14.
15.
Mallon EB Loosli R Schmid-Hempel P 《Evolution; international journal of organic evolution》2003,57(6):1444-1447
Abstract.— Hosts vary in both their strength of response to a general immunological insult and in their specific susceptibility to different parasite species or different strains of the same parasite. The variation in the general immune response is considered a result of the costs imposed by selection on defended individuals. The variation in the specific response may originate from variation in host and parasite genotypes and is a requirement for frequency-dependent selection. The relationship between these two fundamental aspects of defense has only rarely been studied. Using the bumblebee Bombus terrestris and its gut trypanosomal parasite Crithidia bombi we found that the host's specific response profile toward different strains correlates negatively with its level of response to a general insult. This is the opposite result one would expect if the level of general response were simply a measure of immunological quality (immunocompetence). Rather, it suggests that there is some form of a trade-off between these two fundamental aspects of the immune system. These results, therefore, shed an important light on the possible constraints that affect the evolution of the immune system and particularly the trade-off between different arms of the immune system. 相似文献
16.
17.
Mario X. Ruiz‐González John Bryden Yannick Moret Christine Reber‐Funk Paul Schmid‐Hempel Mark J. F. Brown 《Evolution; international journal of organic evolution》2012,66(10):3053-3066
The evolutionary ecology of multihost parasites is predicted to depend upon patterns of host quality and the dynamics of transmission networks. Depending upon the differences in host quality and transmission asymmetries, as well as the balance between intra‐ and interspecific transmission, the evolution of specialist or generalist strategies is predicted. Using a trypanosome parasite of bumblebees, we ask how host quality and transmission networks relate to parasite population structure across host species, and thus the potential for the evolution of specialist strains adapted to different host species. Host species differed in quality, with parasite growth varying across host species. Highly asymmetric transmission networks, together with differences in host quality, likely explain local population structure of the parasite across host species. However, parasite population structure across years was highly dynamic, with parasite populations varying significantly from one year to the next within individual species at a given site. This suggests that, while host quality and transmission may provide the opportunity for short‐term host specialization by the parasite, repeated bottlenecking of the parasite, in combination with its own reproductive biology, overrides these smaller scale effects, resulting in the evolution of a generalist parasite. 相似文献
18.
Abstract 1. Experimental studies of multihost parasite dynamics are scarce. Understanding the transmission dynamics of parasites in these systems is a key task in developing better models of parasite evolution and to make more accurate predictions of disease dynamics. 2. Bumblebee species (Bombus spp.) host the trypanosomatid parasite, Crithidia bombi. Its transmission in the field occurs through the shared use of flowers. Flowers are a perfect scenario for inter‐taxa transmission of diseases because they are used by a wide range of animals. 3. Honey bees host a poorly studied trypanosomatid, Crithidia mellificae. In this study, five questions have been experimentally addressed: (a) Can C. bombi infect honey bees? (b) Can C. mellificae infect bumblebees? (c) Can the honey bee act as a vector for C. bombi? (d) Are C. bombi cells present in honey‐bee faeces? (e) Does C. bombi have an effect on the mortality of honey bees after ingestion? 4. While both parasites were found to be specific to their hosts at the genus level, results suggest that honey bees may play a role in the epidemiology of C. bombi transmission. 相似文献
19.
Paul Schmid-Hempel Katina Puhr Nadja Krüger Christine Reber Regula Schmid-Hempel 《Evolution; international journal of organic evolution》1999,53(2):426-434
Transmission to a new host is a critical step in the life cycle of a parasite. Variation in the characteristics of the transmission process, for example, due to host demography, is assumed to select for different variants of the parasite. We have experimentally tested how variation in the time to transmission (early or late after infection) and exposure to adverse conditions outside the host (immediate or delayed contact with new host) interact to determine the success of the infection in the next host, using the trypanosome Crithidia bombi infecting its bumblebee host, Bombus terrestris. These two experimentally manageable steps mimic the processes of within- and among-host selection for the parasite. We found that early transmission led to higher infection success in the next host as did immediate contact with the new host. However, there was no interaction between the two parameters as would be expected if early-transmitted variants, resulting from rapid multiplication within the host, would be less adapted to the conditions encountered during the between-host transfer or infection of the next host. Furthermore, typing the genetic variability of the parasites with microsatellites showed that the four different transmission routes of our experiment selected for different degrees of allelic diversity of the infecting parasite populations. The results support the idea that variation in the transmission process selects for different genotypic variants of the parasite. At the same time, the relationship of allelic diversity with infection intensity suggested that the coinfection model of May and Nowak (1995) may be appropriate, where each parasite is able to infect and multiply independent of others within the same host. 相似文献
20.
George M. LoCascio River Pasquale Eugene Amponsah Rebecca E. Irwin Lynn S. Adler 《Ecological Entomology》2019,44(5):702-710
1. Several bee species are declining due to multiple factors, including pathogens. Ingestion of sunflower (Helianthus annuus) pollen can dramatically reduce the bumble bee gut pathogen Crithidia bombi, but little is known about how timing and exposure to sunflower pollen consumption affects pathogen load. 2. Two experiments were carried out to investigate how exposure to sunflower pollen relative to pathogen exposure affects Crithidia bombi in Bombus impatiens. Foraging trials with pollen‐producing and male‐sterile (pollen absent) sunflower lines were performed to investigate whether sunflower pollen affected pathogen transmission in a single foraging bout, and 7‐day laboratory trials were done to investigate whether timing and duration of exposure to sunflower pollen after infection affected C. bombi. 3. In foraging trials, pollen presence on inflorescences inoculated with C. bombi did not affect transmission (pathogen cell counts of foraging workers) 1 week later, suggesting that a brief experience with sunflower pollen concurrent with pathogen exposure is insufficient to reduce infection. In laboratory trials, consuming sunflower pollen for the first 3.5 days or all 7 days after infection reduced cell counts compared with a negative control pollen, but consuming sunflower pollen starting 3.5 days after infection did not. Consuming sunflower pollen for 7 days was significantly and substantially more effective than any other treatment. Thus, both duration and timing of exposure to sunflower pollen may affect pathogen load. 4. These results are important for understanding ecological disease dynamics in natural settings with free‐flying bumble bees, and may inform decisions about using medicinal diets to manage bumble bee health commercially. 相似文献