scholarly journals Population Dynamics of a Naturally Occurring Heterogeneous Mixture of Borrelia burgdorferiClones

1999 ◽  
Vol 67 (11) ◽  
pp. 5709-5716 ◽  
Author(s):  
Erik K. Hofmeister ◽  
Gregory E. Glass ◽  
James E. Childs ◽  
David H. Persing
Keyword(s):  
Ixodes Scapularis ◽  
Surface Protein ◽  
Random Fluctuation ◽  
Free Living ◽  
Electrophoretic Mobilities ◽  
Naturally Occurring ◽  
Secondary Challenge ◽  
Plasmid Analysis ◽  
C3h Mice ◽  
Sequential Infection

ABSTRACT Two unique isolates of Borrelia burgdorferi, differing in plasmid content and outer surface protein C expression, were cultured on sequential captures of a single free-livingPeromyscus leucopus mouse and were examined for differences in transmissibility. Both isolates were transmissible from inoculated C.B-17 mice to larval Ixodes scapularis ticks and, subsequently, from infected nymphal ticks to C3H/HeJ mice. Plasmid and protein analyses suggested that the original isolates were a mixed population of B. burgdorferi, and cloning by limiting dilution resulted in the identification of two clonal groups. In addition to being heterogeneous in plasmid and genomic macrorestriction analyses, the clones varied with respect to the electrophoretic mobilities and antigenicity of their OspC proteins, as shown by their reactivity to a panel of monoclonal antibodies. Plasmid analysis of sequential isolates from C3H mice experimentally infected with the primary isolate or various mixtures of its subclones showed an apparently random fluctuation in clonal dominance in the majority of mice. Surprisingly, mice infected with each subclone were permissive to superinfection with the heterologous subclone, despite the presence of anti-B. burgdorferi antibodies at the time of the secondary challenge. These results show conclusively that mice captured at Lyme disease enzootic sites may be infected by mixed populations of genetically and antigenically distinct B. burgdorfericlones and that these infections can be acquired by coinfection or by sequential infection. The lack of cross-immunization between clones existing within a naturally occurring population may play a role in the maintenance of the genetic heterogeneity of B. burgdorferiin nature.

scholarly journals Methods for Estimating Gene Frequencies and Detecting Selection in Bacterial Populations

Genetics ◽  
2000 ◽  
Vol 155 (2) ◽  
pp. 499-508 ◽  
Author(s):  
Bruce Rannala ◽  
Wei-Gang Qiu ◽  
Daniel E Dykhuizen
Keyword(s):  
Ixodes Scapularis ◽  
Balancing Selection ◽  
Surface Protein ◽  
Allele Frequencies ◽  
Gene Frequencies ◽  
Bacterial Populations ◽  
Polymerase Chain ◽  
Host Infection ◽  
Infinite Alleles Model

Abstract Recent breakthroughs in molecular technology, most significantly the polymerase chain reaction (PCR) and in situ hybridization, have allowed the detection of genetic variation in bacterial communities without prior cultivation. These methods often produce data in the form of the presence or absence of alleles or genotypes, however, rather than counts of alleles. Using relative allele frequencies from presence-absence data as estimates of population allele frequencies tends to underestimate the frequencies of common alleles and overestimate those of rare ones, potentially biasing the results of a test of neutrality in favor of balancing selection. In this study, a maximum-likelihood estimator (MLE) of bacterial allele frequencies designed for use with presence-absence data is derived using an explicit stochastic model of the host infection (or bacterial sampling) process. The performance of the MLE is evaluated using computer simulation and a method is presented for evaluating the fit of estimated allele frequencies to the neutral infinite alleles model (IAM). The methods are applied to estimate allele frequencies at two outer surface protein loci (ospA and ospC) of the Lyme disease spirochete, Borrelia burgdorferi, infecting local populations of deer ticks (Ixodes scapularis) and to test the fit to a neutral IAM.

Interactions between DNA-bound trimers of the yeast heat shock factor

1994 ◽  
Vol 14 (1) ◽  
pp. 501-508
Author(s):  
J J Bonner ◽  
C Ballou ◽  
D L Fackenthal
Keyword(s):  
Heat Shock ◽  
Protein Complexes ◽  
Consensus Sequence ◽  
The Other ◽  
Inverted Repeats ◽  
Electrophoretic Mobilities ◽  
Naturally Occurring ◽  
Initial Identification ◽  
Dyad Symmetry ◽  
Chemical Cross Linking

The heat shock transcription factor (HSF) is a trimer that binds to DNA containing inverted repeats of the sequence nGAAn. HSF can bind DNA with the sequence nGAAnnTTCn or with the sequence nTTCnnGAAn, with little preference for either sequence over the other. However, (nGAAnnTTCn)2 is considerably less active as a heat shock response element (HSE) than is (nTTCnnGAAn)2. The electrophoretic mobilities of DNA-protein complexes and chemical cross-linking between protein monomers indicate that the sequence (nGAAnnTTCn)2 is capable of binding a single HSF trimer. In contrast, the sequence with higher biological activity, (nTTCnnGAAn)2, is capable of binding two trimers. Thus, the ability of four-nGAAn-element HSEs to bind one or two trimers depends on the permutation with which the elements are presented. A survey of naturally occurring HSEs shows the sequence (nTTCnnGAAn)2 to be the more prevalent. We suggest that the greater ability of one permutation over the other to bind two HSF trimers accounts for the initial identification of the naturally occurring heat shock consensus sequence as a region of dyad symmetry.

scholarly journals Plastic, nutrition and pollution; relationships between ingested plastic and metal concentrations in the livers of two Pachyptila seabirds

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Lauren Roman ◽  
Farzana Kastury ◽  
Sophie Petit ◽  
Rina Aleman ◽  
Chris Wilcox ◽  
...  
Keyword(s):  
Health Hazard ◽  
Dietary Exposure ◽  
The Body ◽  
Free Living ◽  
Seabird Species ◽  
Significant Relationships ◽  
Naturally Occurring ◽  
Plastic Metal ◽  
Liver Concentration ◽  
New Evidence

Abstract Naturally occurring metals and metalloids [metal(loid)s] are essential for the physiological functioning of wildlife; however, environmental contamination by metal(loid) and plastic pollutants is a health hazard. Metal(loid)s may interact with plastic in the environment and there is mixed evidence about whether plastic ingested by wildlife affects metal(loid) absorption/assimilation and concentration in the body. We examined ingested plastic and liver concentration of eleven metal(loid)s in two seabird species: fairy (Pachyptila turtur) and slender-billed prions (P. belcheri). We found significant relationships between ingested plastic and the concentrations of aluminium (Al), manganese (Mn), iron (Fe), cobalt (Co), copper (Cu) and zinc (Zn) in the liver of prions. We investigated whether the pattern of significant relationships reflected plastic-metal(loid) associations predicted in the scientific literature, including by transfer of metals from ingested plastics or malnutrition due to dietary dilution by plastics in the gut. We found some support for both associations, suggesting that ingested plastic may be connected with dietary dilution / lack of essential nutrients, especially iron, and potential transfer of zinc. We did not find a relationship between plastic and non-essential metal(loid)s, including lead. The effect of plastic was minor compared to that of dietary exposure to metal(oid)s, and small plastic loads (< 3 items) had no discernible link with metal(loid)s. This new evidence shows a relationship between plastic ingestion and liver metal(loid) concentrations in free-living wildlife.

scholarly journals The human pathogenic vibrios – A public health update with environmental perspectives

1989 ◽  
Vol 103 (1) ◽  
pp. 1-34 ◽  
Author(s):  
P. A. West
Keyword(s):  
Public Health ◽  
Acute Infection ◽  
Aquatic Environments ◽  
Free Living ◽  
Liver Disorders ◽  
Naturally Occurring ◽  
Pathogenic Vibrio ◽  
Ear Infections ◽  
Pathogenic Vibrios ◽  
Living Bacteria

PathogenicVibriospecies are naturally-occurring bacteria in freshwater and saline aquatic environments. Counts of free-living bacteria in water are generally less than required to induce disease. Increases in number of organisms towards an infective dose can occur as water temperatures rise seasonally followed by growth and concentration of bacteria on higher animals, such as chitinous plankton, or accumulation by shellfish and seafood. PathogenicVibriospecies must elaborate a series of virulence factors to elicit disease in humans.Activities which predispose diarrhoeal and extraintestinal infections include ingestion of seafood and shellfish and occupational or recreational exposure to natural aquatic environments, especially those above 20 °C. Travel to areas endemic for diseases due to pathogenicVibriospecies may be associated with infections. Host risk factors strongly associated with infections are lack of gastric acid and liver disorders.Involvement of pathogenicVibriospecies in cases of diarrhoea should be suspected especially if infection is associated with ingestion of seafood or shellfish, raw or undercooked, in the previous 72 h.Vibriospecies should be suspected in any acute infection associated with wounds sustained or exposed in the marine or estuarine environment. Laboratories serving coastal areas where infection due to pathogenic Vibrio species are most likely to occur should consider routine use of TCBS agar and other detection regimens for culture ofVibriospecies from faeces, blood and samples from wound and ear infections.

scholarly journals Plasmodium falciparum Merozoite Surface Protein 6 Displays Multiple Targets for Naturally Occurring Antibodies That Mediate Monocyte-Dependent Parasite Killing

2005 ◽  
Vol 73 (2) ◽  
pp. 1235-1238 ◽  
Author(s):  
Subhash Singh ◽  
Soe Soe ◽  
Christian Roussilhon ◽  
Giampietro Corradin ◽  
Pierre Druilhe
Keyword(s):  
Plasmodium Falciparum ◽  
Surface Protein ◽  
Merozoite Surface Protein ◽  
Naturally Occurring ◽  
C Terminus ◽  
Sequence Homologies ◽  
Merozoite Surface Antigen ◽  
Falciparum Merozoite ◽  
Erythrocytic Cycle ◽  
Naturally Occurring Antibodies

ABSTRACT Plasmodium falciparum MSP6 is a merozoite surface antigen that shows organization and sequence homologies similar to those of MSP3. Within its C-terminus conserved region, it presents some epitopes that are cross-reactive with MSP3 and others that are not, both being targets of naturally occurring antibodies that block the P. falciparum erythrocytic cycle in cooperation with monocytes.

scholarly journals TrackingBorrelia afzeliifrom infectedIxodes ricinusnymphs to mice suggests a direct ‘gut-to-mouth’ route of Lyme disease transmission

2018 ◽  
Author(s):  
Tereza Pospisilova ◽  
Veronika Urbanova ◽  
Ondrej Hes ◽  
Petr Kopacek ◽  
Ondrej Hajdusek ◽  
...  
Keyword(s):  
Salivary Glands ◽  
Lyme Borreliosis ◽  
Disease Transmission ◽  
Ixodes Scapularis ◽  
Surface Protein ◽  
Gut Contents ◽  
Tick Saliva ◽  
Borrelia Afzelii ◽  
Transmission Cycle ◽  
Main Requirement

AbstractQuantitative tracking ofBorrelia afzeliihas shown that its transmission cycle differs from the salivary route ofB. burgdorferitransmission byIxodes scapularis.Borrelia afzeliiare abundant in the guts of unfedIxodes ricinusnymphs and their numbers continuously decrease during feeding. In contrast, spirochetes are not present in the salivary glands.Borrelia afzeliitransmission starts during the early stages of feeding, spirochetes could be detected in murine skin within 1 day of tick attachment. Tick saliva is not essential forB. afzeliiinfectivity, the main requirement for successful host colonization being a change in outer surface protein expression that occurs in the tick gut during feeding. Spirochetes in vertebrate mode are able to survive within the host even if the tick is not present. On the basis of our data we propose that a direct ‘gut-to-mouth’ route of infection appears to be the main route ofB. afzeliitransmission.ImportanceLyme borreliosis is the most common vector-borne disease in the USA and Europe. The disease is caused by theBorreliaspirochetes and is transmitted throughIxodesticks. A better understanding of howBorreliaspirochetes are transmitted is crucial for development of efficient vaccines for preventing Lyme borreliosis. Here we present that the transmission of EuropeanB. afzeliispirochetes byI. ricinusticks significantly differs from the model transmission cycle described for AmericanB. burgdorferi/I. scapularis. We suggest thatB. afzeliiis not transmitted via salivary glands but most likely through the ‘midgut to mouthpart’ route. We further demonstrate that tick saliva is not important forB. afzeliitransmission and infectivity. Therefore, we support early studies by Willy Burgdorfer, who proposed thatBorreliatransmission occurs by regurgitation of infected gut contents. Our findings collectively point to theBorrelia-tick midgut interface as the correct target in our endeavours to combat Lyme borreliosis.

Naturally Occurring Biofilms on Alfalfa and Other Types of Sprouts†

2000 ◽  
Vol 63 (5) ◽  
pp. 625-632 ◽  
Author(s):  
WILLIAM F. FETT
Keyword(s):  
Yeast Cells ◽  
Escherichia Coli O157 ◽  
Antimicrobial Compounds ◽  
Human Pathogens ◽  
Free Living ◽  
Plant Parts ◽  
Naturally Occurring ◽  
Retail Outlets ◽  
Alfalfa Sprouts ◽  
Bacterial Exopolysaccharides

Scanning electron microscopy was used to examine the cotyledons, hypocotyls, and roots of alfalfa, broccoli, clover, and sunflower sprouts purchased from retail outlets as well as alfalfa sprouts grown in the laboratory using a tray system equipped with automatic irrigation. Biofilms were observed on all plant parts of the four types of commercially grown sprouts. Biofilms were also commonly observed on alfalfa sprouts grown in the laboratory by 2 days of growth. Rod-shaped bacteria of various sizes were predominant on all sprouts examined both as free-living cells and as components of biofilms. Occasionally, cocci-shaped bacteria as well as yeast cells were also present in biofilms. The microbes contained in the biofilms appeared to be attached to each other and to the plant surface by a matrix, most likely composed of bacterial exopolysaccharides. Biofilms were most abundant and of the largest dimensions on cotyledons, sometimes covering close to the entire cotyledon surface (approximately 2 mm in length). Naturally occurring biofilms on sprouts may afford protected colonization sites for human pathogens such as Salmonella and Escherichia coli O157:H7, making their eradication with antimicrobial compounds difficult.

scholarly journals Attachment of Borrelia burgdorferi within Ixodes scapularis mediated by outer surface protein A

2000 ◽  
Vol 106 (4) ◽  
pp. 561-569 ◽  
Author(s):  
Utpal Pal ◽  
Aravinda M. de Silva ◽  
Ruth R. Montgomery ◽  
Durland Fish ◽  
Juan Anguita ◽  
...  
Keyword(s):  
Borrelia Burgdorferi ◽  
Outer Surface ◽  
Ixodes Scapularis ◽  
Protein A ◽  
Surface Protein ◽  
Outer Surface Protein A ◽  
Outer Surface Protein

scholarly journals Growth dynamics and antibiotic elimination of symbiotic Rickettsia buchneri in the tick Ixodes scapularis (Acari: Ixodidae)

2020 ◽  
Author(s):  
Jonathan D. Oliver ◽  
Lisa D. Price ◽  
Nicole Y. Burkhardt ◽  
Chan C. Heu ◽  
Benedict S. Khoo ◽  
...  
Keyword(s):  
Life Cycle ◽  
Ixodes Scapularis ◽  
Growth Dynamics ◽  
Symbiotic Bacterium ◽  
Ease Of Use ◽  
Life Stages ◽  
Artificial Membrane ◽  
Naturally Occurring ◽  
Membrane Feeding ◽  
And Function

Rickettsia buchneri is the principal symbiotic bacterium of the medically significant tick, Ixodes scapularis. This species has been detected primarily in the ovary of adult female ticks and is vertically transmitted, but its tissue-tropism in other life stages and function in regard to tick physiology is unknown. In order to determine the function of R. buchneri, it may be necessary to produce ticks free from this symbiont. We quantified the growth dynamics of R. buchneri naturally occurring in I. scapularis ticks throughout their life cycle and compared it with bacterial growth in ticks in which symbiont numbers were experimentally reduced or eliminated. To eliminate the bacteria, we exposed ticks to antibiotics through injection and artificial membrane feeding. Both injection and membrane feeding of the antibiotic ciprofloxacin were effective at eliminating R. buchneri from most offspring of exposed females. Because of its effectiveness and ease of use, we have determined that injection of ciprofloxacin into engorged female ticks is an efficient means of clearing R. buchneri from the majority of progeny. IMPORTANCE Describes the growth of symbiotic Rickettsia buchneri within Ixodes scapularis through the life cycle of the tick. Provides methods to eliminate R. buchneri from I. scapularis ticks.

Sign in / Sign up

Export Citation Format

Share Document