Restriction endonuclease analysis of four Borrelia burgdorferi strains

Abstract A restriction endonuclease analysis was performed on four strains of Borrelia burgdorferi : one isolated from man (SF), one from Ixodes dammini (B31) and two form I. ricinus (BITS in Italy and B45 in Germany). Digestion by Taq I and Hae III gave the best resolution of the DNA fragments. Three different restriction patterns were obtained: BITS and B45 showed only one band difference. These results correlate with the reactivity of the four strains with monoclonal antibodies.     

Restriction endonuclease analysis of four Borrelia burgdorferi strains

A restriction endonuclease analysis was performed on four strains of Borrelia burgdorferi: one isolated from man (SF), one from Ixodes dammini (B31) and two from I. ricinus (BITS in Italy and B45 in Germany). Digestion by Taq I and Hae III gave the best resolution of the DNA fragments. Three different restriction patterns were obtained: BITS and B45 showed only one band difference. These results correlate with the reactivity of the four strains with monoclonal antibodies.     

Diverse Borrelia burgdorferi strains in a bird-tick cryptic cycle

The blacklegged tick Ixodes scapularis is the primary vector of the most prevalent vector-borne zoonosis in North America, Lyme disease (LD). Enzootic maintenance of the pathogen Borrelia burgdorferi by I. scapularis and small mammals is well documented, whereas its "cryptic" maintenance by other specialist ticks and wildlife hosts remains largely unexplored because these ticks rarely bite humans. We quantified B. burgdorferi infection in a cryptic bird-rabbit-tick cycle. Furthermore, we explored the role of birds in maintaining and moving B. burgdorferi strains by comparing their genetic diversity in this cryptic cycle to that found in cycles vectored by I. scapularis. We examined birds, rabbits, and small mammals for ticks and infection over a 4-year period at a focal site in Michigan, 90 km east of a zone of I. scapularis invasion. We mist netted 19,631 birds that yielded 12,301 ticks, of which 86% were I. dentatus, a bird-rabbit specialist. No resident wildlife harbored I. scapularis, and yet 3.5% of bird-derived ticks, 3.6% of rabbit-derived ticks, and 20% of rabbit ear biopsy specimens were infected with B. burgdorferi. We identified 25 closely related B. burgdorferi strains using an rRNA gene intergenic spacer marker, the majority (68%) of which had not been reported previously. The presence of strains common to both cryptic and endemic cycles strongly implies bird-mediated dispersal. Given continued large-scale expansion of I. scapularis populations, we predict that its invasion into zones of cryptic transmission will allow for bridging of novel pathogen strains to humans and animals.     

Laboratory observations of benthic foraminiferal cysts

Long-term observations on living benthic foraminifera in the laboratory were performed to investigate their behaviour and life style. We noticed that the formation of cysts or sedimentary envelopes is a common feature within many groups of foraminifera (organic walled, agglutinated and calcareous) in the laboratory. Several kinds of cyst were observed. In most cases, the entire foraminiferal shell was canopied with detritus or particles, but some specimens covered only parts of their body, such as the aperture region or pseudopods. Cysts were found attached to the glass walls of culture vessels or free in and on the sediment. Foraminifera stayed within cysts for hours to weeks. After leaving sedimentary envelopes, some specimens immediately started to build new ones, others not. The function of cyst formation observed in the present study was not clear, except one case where reproduction took place. Some monitored structures seemed not to be sedimentary cysts but unilocular agglutinated foraminifera with probably allogromiid-like organization. The formation of sedimentary envelopes seems to be a very basic character of foraminifera, suggesting a mechanism for the evolution of shells.     

Laboratory observations on locust responses to wind-borne grass odour

Starved desert locust hoppers respond to wind-borne grass odour by turning and moving upwind toward the odour source. The conclusion from previous work, that this orientation reaction depends on unequal olfactory stimulation of the two antennae (osmotropotaxis), has been re-examined in further experiments. Agitating hoppers, by handling them singly or by tumbling a crowd of them together just before releasing them in a wind tunnel, induced rapid upwind movement by both starved and fed hoppers even in the absence of grass odour. Repeated agitation led to increasing locomotor excitability accompanied by increasing upwind bias. Bilateral antennectomy depressed activity, but agitated antennaless hoppers also moved upwind with an without grass odour, provided they were very starved. Vaselining or amputating one antenna, or fixing the two antennae in a crossed-over position, impaired but did not prevent upwind-orientated movement in response to grass odour. It is concluded that the normal upwind movement in response to grass odour is not osmotropotaxis but anemotaxis: the grass odour activates the insects and at the same time switches on their positive orientation reaction to the wind itself. A repellent odour also activates the insects and induces anemotaxis, which is now negative. Thus a variety of stimuli which excite locomotor activity simultaneously switch on anemotaxis, either positive or negative.

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Résumé A jeun les larves du criquet pélerin réagissent à l'odeur d'herbe apportée par le vent en se tournant et en se déplaçant face au vent vers le lieu d'où vient l'odeur. Cette orientation avait été attributée, à la suite de travaux antérieurs, à la stimulation olfactive inégale des deux antennes (osmotropotaxie). Ce phénomène a été réexaminé.L'agitation des larves, soit par maniement individuel, soit par secouage en masse, juste avant de les lâcher dans un tunnel aerodynamique, a eu pour effet sur les larves, qu'elles fussent à jeun ou rassasiées, de les faire se diriger face au vent même en l'absence d'odeur d'herbe. La répétition de ce traitement a accru l'excitabilité locomotrice et également la tendance à aller contre le vent. L'antennectomie bilatérale a réduit l'activité locomotrice mais ces larves sans antennes, préalablement agitées, se sont aussi dirigées contre le vent avec ou sans odeur d'herbe, à condition qu'elles aient été longtemps à jeun.En vaselinant une antenne, ou en faisant l'ablation unilatérale, ou encore en entrecroisant les deux antennes, on a atténué mais non pas supprimé le processus d'orientation face au vent en présence de l'odeur d'herbe.Il en a été conclu que le déplacement normal contre le vent en présence de l'odeur d'herbe n'est pas une osmotropotaxie mais une anémotaxie positive; en faite, l'odeur active bien les criquets et en même temps déclenche une réaction d'orientation au vent. Une odeur repoussante active aussi les criquets et déclenche l'anémotaxie, cette fois négative. Donc differents stimuli qui excitent l'activité locomotrice déclenchent en même temps une anémo taxie positive ou négative.

     

DNA homology comparison between American and European Borrelia burgdorferi strains

Seven strains of Borrelia burgdorferi isolated from ticks and from human beings in Europe and U.S.A. were analyzed for DNA restriction patterns with several enzymes and for DNA homology in Southern blot hybridizations. The restriction patterns showed a moderately high variability. In Southern blot hybridization, strain B31 (U.S.A.) DNA gave a strong signal with itself, strain Bsf (U.S.A.) and Alcaide (isolated in Italy but presumably contracted in Venezuela). Strain B45 (F.R.G.) hybridized to itself, strain BITS (Italy) and to strain D.A. (Italy). Strain Nancy (Italy) gave a signal only when hybridized to itself, although it was classified as Borrelia on the basis of the clinical manifestations, SDS-PAGE protein pattern and antigenic determinants. No hybridization differences were observed for strains isolated from different hosts in the same continental geographical area.     

Laboratory observations on the insusceptibility of raccoons to Dirofilaria immitis

Two raccoons, Procyon lotor, were exposed to Dirofilaria immitis by subcutaneous injection of infective third stage larvae obtained from experimentally-infected Aedes trivittatus. Nematodes were not recovered from either raccoon when examined at necropsy 223 and 254 days postexposure. Large numbers of adult D. immitis were found in six dogs used as controls. These data indicate that raccoons cannot support the development of D. immitis.     

Laboratory evolution of copper tolerant yeast strains

Background  

Yeast strains endowed with robustness towards copper and/or enriched in intracellular Cu might find application in biotechnology processes, among others in the production of functional foods. Moreover, they can contribute to the study of human diseases related to impairments of copper metabolism. In this study, we investigated the molecular and physiological factors that confer copper tolerance to strains of baker's yeasts.     

Biodiversity of Borrelia burgdorferi strains in tissues of Lyme disease patients

Plant and animal biodiversity are essential to ecosystem health and can provide benefits to humans ranging from aesthetics to maintaining air quality. Although the importance of biodiversity to ecology and conservation biology is obvious, such measures have not been applied to strains of an invasive bacterium found in human tissues during infection. In this study, we compared the strain biodiversity of Borrelia burgdorferi found in tick populations with that found in skin, blood, synovial fluid or cerebrospinal fluid of Lyme disease patients. The biodiversity of B. burgdorferi strains is significantly greater in tick populations than in the skin of patients with erythema migrans. In turn, strains from skin are significantly more diverse than strains at any of the disseminated sites. The cerebrospinal fluid of patients with neurologic Lyme disease harbored the least pathogen biodiversity. These results suggest that human tissues act as niches that can allow entry to or maintain only a subset of the total pathogen population. These data help to explain prior clinical observations on the natural history of B. burgdorferi infection and raise several questions that may help to direct future research to better understand the pathogenesis of this infection.     

Some observations on the biology of five strains of Eimeria necatrix

Five laboratory strains of Eimeria necatrix were characterised with regard to the size of their oocysts, pathogenicity, reproduction, cross-immunity, ability to grow in embryonated eggs, and electrophoretic variation of enzymes. Three strains were highly pathogenic whilst two caused only few deaths and milder changes to the mean body weight gains of infected chickens. Cross-immunity was incomplete judged by scores of lesions after heterologous challenge, and electrophoretic variation of the enzymes lactate dehydrogenase and isocitrate dehydrogenase from oocysts of the five strains was also found. All the strains completed their life cycle in embryonated eggs but only a few oocysts were recovered.