scholarly journals Competition between strains of Borrelia afzelii in the host tissues and consequences for transmission to ticks

2021 ◽  
Author(s):  
Dolores Genné ◽  
Marika Rossel ◽  
Anouk Sarr ◽  
Florian Battilotti ◽  
Olivier Rais ◽  
...  
Keyword(s):  
Bacterial Abundance ◽  
Infection Prevalence ◽  
Mixed Infections ◽  
Strongly Correlated ◽  
Borrelia Afzelii ◽  
Tick Vector ◽  
Transmission Success ◽  
The Relationship ◽  
Host Tissues ◽  
Pathogen Strains

AbstractPathogen species often consist of genetically distinct strains, which can establish mixed infections or coinfections in the host. In coinfections, interactions between pathogen strains can have important consequences for their transmission success. We used the tick-borne bacterium Borrelia afzelii, which is the most common cause of Lyme disease in Europe, as a model multi-strain pathogen to investigate the relationship between coinfection, competition between strains, and strain-specific transmission success. Mus musculus mice were infected with one or two strains of B. afzelii, strain transmission success was measured by feeding ticks on mice, and the distribution of each strain in six different mouse organs and the ticks was measured using qPCR. Coinfection and competition reduced the tissue infection prevalence of both strains and changed their bacterial abundance in some tissues. Coinfection and competition also reduced the transmission success of the B. afzelii strains from the infected hosts to feeding ticks. The ability of the B. afzelii strains to establish infection in the host tissues was strongly correlated with their transmission success to the tick vector. Our study demonstrates that coinfection and competition between pathogen strains inside the host tissues can have major consequences for their transmission success.

scholarly journals Inter-stain interactions of a vector-borne parasite over its life cycle, "Borrelia afzelii", "Mus musculus", "Ixodes ricinus" model

2021 ◽  
Author(s):  
◽  
Dolores Genné Vizcardo
Keyword(s):  
Life Cycle ◽  
Mixed Infections ◽  
Arthropod Vector ◽  
Transmission Success ◽  
Tick Transmission ◽  
Vector Borne ◽  
Host Tissues ◽  
Pathogen Strains ◽  
Swiss Strain

Many pathogens consist of genetically distinct strains. When hosts are simultaneously infected with multiple strains the phenomenon is known as a mixed infection or a co-infection. In mixed infections, strains can interact with each other and these interactions between strains can have important consequences for their transmission and frequency in the pathogen population. Vector-borne pathogens have a complex life cycle that includes both a vertebrate host and an arthropod vector. As a result of this complexity, interactions between strains can occur in both the host and the vector. Interactions between strains in the vertebrate host are expected to influence transmission from the co-infected host to uninfected vectors. Conversely, interactions between strains in the arthropod vector are expected to influence transmission from the co-infected vector to the uninfected host. This thesis used the tick-borne bacterium, Borrelia afzelii, as a model system to investigate how co-infection and interactions between strains influence their transmission and lifetime fitness over the course of the tick-borne life cycle. B. afzelii is a common cause of Lyme disease in Europe, it is transmitted by the castor bean tick (Ixodes ricinus) and it uses small mammals (e.g. rodents) as a reservoir host. An experimental approach with two genetically distinct strains of B. afzelii (one Swiss stain, one Finnish strain) was used to investigate the effects of co-infection in both the host and the vector. In Chapter 1, lab mice were experimentally infected via tick bite with either 1 or 2 strains of B. afzelii. The infected mice were then fed upon by I. ricinus ticks from a laboratory colony to quantify host-to-tick transmission. qPCR was used to determine the presence and abundance of each strain in the ticks. Chapter 1 found that co-infection in the mice reduced the host-to-tick transmission success of the strains. This chapter also found that co-infection reduced the abundance of each strain in the tick. This is one of the first studies to show that co-infection is important for determining the abundance of the pathogen strains in the vector. In the lifecycle of B. afzelii, the bacterium is acquired by larval ticks that blood feed on an infected host. These larvae subsequently moult into nymphs that are responsible for transmitting the bacterium to the next generation of hosts. The bacterium has to persist inside the midgut of the nymph for a long time (8 – 12 months). Chapter 2 investigated whether nymphal ageing (1-month-old vs 4-month-old nymphs) under different environmental conditions (summer vs winter) influenced the interactions between strains in co-infected ticks. The spirochete abundance inside the nymph decreased with nymphal age, but there was no effect of the environmental conditions investigated. In Chapter 3, the presence and abundance of the two strains of B. afzelii were quantified in the tissues of 6 different organs (bladder, left ear, right ear, heart, ankle joint, and dorsal skin) that were harvested from the co-infected and singly infected mice. This study showed that co-infection in the mouse host reduced the prevalence of the Finnish strain in the host tissues (but the Swiss strain was not affected by co-infection). Chapter 3 found a positive relationship between the prevalence (or abundance) of each strain in the mouse tissues and the host-to-tick transmission of each strain. External tissues (e.g. ears) were more important for host-to-tick transmission than internal organs (e.g. bladder). Chapter 3 enhances our understanding of the biology of mixed infections by showing the causal links between co-infection in the host, the distribution and abundance of the strains in host tissues and the subsequent host-to-tick transmission success of the strains. Chapter 4 investigated how co-infection in the arthropod vector influences vector-to-host transmission success. A second infection experiment was performed, where naïve mice were exposed to nymphs that were either co-infected or infected with one of the two strains (i.e., using the nymphs generated in Chapters 1 and 2). The infection status of the mice was then tested using the same qPCR-based methods. Importantly, Chapter 4 confirmed that the negative effect of co-infection in the mouse on host-to-tick transmission (observed in Chapters 1, 2, and 3) had real fitness consequences for subsequent tick-to-host transmission. Ticks that had fed on co-infected mice were much less likely to transmit their strains to the host because these strains were less common inside these co-infected ticks. Chapter 4 did not find evidence that co-infection in the nymph influenced the nymph-to-host transmission success of each strain. This Chapter did find that there was a two-fold difference in nymph-to-host transmission success between the two strains. This work provides evidence for the idea that vector-borne pathogen strains can exhibit trade-offs across the different steps of their complex life cycles. In the co-infected mice, the Swiss strain had higher host-to-tick transmission success than the Finnish strain. Conversely, the Finnish strains had higher spirochete loads in the tick vector and had tick-to-host transmission success. Thus, the Swiss and Finnish strains are specialized on the host versus the vector, respectively.

scholarly journals Competition between strains of Borrelia afzelii inside the rodent host and the tick vector

2018 ◽  
Vol 285 (1890) ◽  
pp. 20181804 ◽  
Author(s):  
Dolores Genné ◽  
Anouk Sarr ◽  
Andrea Gomez-Chamorro ◽  
Jonas Durand ◽  
Claire Cayol ◽  
...  
Keyword(s):  
Competitive Ability ◽  
Vertebrate Host ◽  
Mixed Infections ◽  
Rodent Host ◽  
Borrelia Afzelii ◽  
Arthropod Vector ◽  
Tick Vector ◽  
Trade Offs ◽  
Tick Transmission ◽  
Vector Borne

Multiple-strain pathogens often establish mixed infections inside the host that result in competition between strains. In vector-borne pathogens, the competitive ability of strains must be measured in both the vertebrate host and the arthropod vector to understand the outcome of competition. Such studies could reveal the existence of trade-offs in competitive ability between different host types. We used the tick-borne bacterium Borrelia afzelii to test for competition between strains in the rodent host and the tick vector, and to test for a trade-off in competitive ability between these two host types. Mice were infected via tick bite with either one or two strains, and these mice were subsequently used to create ticks with single or mixed infections. Competition in the rodent host reduced strain-specific host-to-tick transmission and competition in the tick vector reduced the abundance of both strains. The strain that was competitively superior in host-to-tick transmission was competitively inferior with respect to bacterial abundance in the tick. This study suggests that in multiple-strain vector-borne pathogens there are trade-offs in competitive ability between the vertebrate host and the arthropod vector. Such trade-offs could play an important role in the coexistence of pathogen strains.

scholarly journals Denitrifying bacterial communities in surface-flow constructed wetlands during different seasons: characteristics and relationships with environment factors

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jia-ming Wei ◽  
Li-juan Cui ◽  
Wei Li ◽  
Yun-mei Ping ◽  
Wan Li
Keyword(s):  
Environmental Factors ◽  
High Throughput Sequencing ◽  
Bacterial Abundance ◽  
Flow Direction ◽  
Denitrifying Bacteria ◽  
Surface Flow ◽  
Strongly Correlated ◽  
Community Structures ◽  
Oxidation Reduction ◽  
Different Seasons

AbstractDenitrification is an important part of the nitrogen cycle and the key step to removal of nitrogen in surface-flow wetlands. In this study, we explored space–time analysis with high-throughput sequencing to elucidate the relationships between denitrifying bacteria community structures and environmental factors during different seasons. Our results showed that along the flow direction of different processing units, there were dynamic changes in physical and chemical indicators. The bacterial abundance indexes (ACEs) in May, August, and October were 686.8, 686.8, and 996.2, respectively, whereas the Shannon-Weiner indexes were 3.718, 4.303, and 4.432, respectively. Along the flow direction, the denitrifying bacterial abundance initially increased and then decreased subsequently during the same months, although diversity tended to increase. The abundance showed similar changes during the different months. Surface flow wetlands mainly contained the following denitrifying bacteria genus: unclassified Bacteria (37.12%), unclassified Proteobacteria (18.16%), Dechloromonas (16.21%), unranked environmental samples (12.51%), unclassified Betaproteobacteria (9.73%), unclassified Rhodocyclaceae (2.14%), and Rhodanobacter (1.51%). During different seasons, the same unit showed alternating changes, and during the same season, bacterial community structures were influenced by the second genus proportion in different processing units. ACEs were strongly correlated with temperature, dissolved oxygen, and pH. Bacterial diversity was strongly correlated with temperature, electrical conductivity, pH, and oxidation reduction potential. Denitrifying bacteria are greatly affected by environmental factors such as temperature and pH.

scholarly journals An analysis of Italian university students’ performance through segmented regression models: gender differences in STEM courses

Genus ◽  
2021 ◽  
Vol 77 (1) ◽  
Author(s):  
Andrea Priulla ◽  
Nicoletta D’Angelo ◽  
Massimo Attanasio
Keyword(s):  
Gender Differences ◽  
Regression Models ◽  
First Year ◽  
Strongly Correlated ◽  
Segmented Regression ◽  
Freshmen Students ◽  
Female Performance ◽  
And Mathematics ◽  
The Relationship ◽  
Better Than

AbstractThis paper investigates gender differences in university performances in Science, Technology, Engineering and Mathematics (STEM) courses in Italy, proposing a novel application through the segmented regression models. The analysis concerns freshmen students enrolled at a 3-year STEM degree in Italian universities in the last decade, with a focus on the relationship between the number of university credits earned during the first year (a good predictor of the regularity of the career) and the probability of getting the bachelor degree within 4 years. Data is provided by the Italian Ministry of University and Research (MIUR). Our analysis confirms that first-year performance is strongly correlated to obtaining a degree within 4 years. Furthermore, our findings show that gender differences vary among STEM courses, in accordance with the care-oriented and technical-oriented dichotomy. Males outperform females in mathematics, physics, chemistry and computer science, while females are slightly better than males in biology. In engineering, female performance seems to follow the male stream. Finally, accounting for other important covariates regarding students, we point out the importance of high school background and students’ demographic characteristics.

How biases in sperm storage relate to sperm use during oviposition in female yellow dung flies

2021 ◽  
Author(s):  
Marco Demont ◽  
Paul I Ward ◽  
Wolf U Blanckenhorn ◽  
Stefan Lüpold ◽  
Oliver Y Martin ◽  
...  
Keyword(s):  
Sperm Competition ◽  
Sperm Storage ◽  
Adaptive Plasticity ◽  
Strongly Correlated ◽  
Scathophaga Stercoraria ◽  
General Importance ◽  
Copula Duration ◽  
Mixed Paternity ◽  
Paternity Success ◽  
The Relationship

Abstract Precise mechanisms underlying sperm storage and utilization are largely unknown, and data directly linking stored sperm to paternity remain scarce. We used competitive microsatellite PCR to study the effects of female morphology, copula duration and oviposition on the proportion of stored sperm provided by the second of two copulating males (S2) in Scathophaga stercoraria (Diptera: Scathophagidae), the classic model for sperm competition studies. We genotyped all offspring from potentially mixed-paternity clutches to establish the relationship between a second male’s stored sperm (S2) and paternity success (P2). We found consistent skew in sperm storage across the three female spermathecae, with relatively more second-male sperm stored in the singlet spermatheca than in the doublet spermathecae. S2 generally decreased with increasing spermathecal size, consistent with either heightened first-male storage in larger spermathecae, or less efficient sperm displacement in them. Additionally, copula duration and several two-way interactions influenced S2, highlighting the complexity of postcopulatory processes and sperm storage. Importantly, S2 and P2 were strongly correlated. Manipulation of the timing of oviposition strongly influenced observed sperm-storage patterns, with higher S2 when females laid no eggs before being sacrificed than when they oviposited between copulations, an observation consistent with adaptive plasticity in insemination. Our results identified multiple factors influencing sperm storage, nevertheless suggesting that the proportion of stored sperm is strongly linked to paternity (i.e., a fair raffle). Even more detailed data in this vein are needed to evaluate the general importance of sperm competition relative to cryptic female choice in postcopulatory sexual selection.

Random serum free cortisol and total cortisol measurements in pediatric septic shock

2018 ◽  
Vol 31 (7) ◽  
pp. 757-762
Author(s):  
Kusum Menon ◽  
Dayre McNally ◽  
Anand Acharya ◽  
Katharine O’Hearn ◽  
Karen Choong ◽  
...  
Keyword(s):  
Septic Shock ◽  
Controlled Trial ◽  
Illness Severity ◽  
Strongly Correlated ◽  
Eligibility Criteria ◽  
Prism Score ◽  
Total Cortisol ◽  
Free Cortisol ◽  
The Relationship ◽  
Strong Agreement

Abstract Background The aim of the study was to examine the relationship between serum total cortisol (TC) and free cortisol (FC) levels in children with septic shock and the relationship of these levels with baseline illness severity. Methods A sub-study of a randomized controlled trial (RCT) of hydrocortisone vs. placebo in pediatric septic shock conducted in seven academic pediatric intensive care units (PICUs) in Canada on children aged newborn to 17 years. Thirty children with septic shock had serum sent for TC and FC measurement within 6 h of meeting the study eligibility criteria. Results Baseline FC and TC levels were strongly correlated with baseline Pediatric Risk of Mortality (PRISM) score (R2=0.759, p<0.001; R2=0.717, p<0.001) and moderately correlated with admission Vasotropic Inotropic Score (VIS) (R2=0.489, p<0.001; R2=0.316, p<0.001). Serum TC levels were highly correlated with FC levels (R2=0.92, p<0.001) and showed strong agreement (R2=0.98, p<0.001 on a Bland-Altman plot). The ratio of FC to TC moderately correlated with TC levels (R2=0.46, p<0.001) but did not correlate with baseline albumin levels (R2=0.19, p=0.13). Conclusions Random TC and FC levels are strongly correlated, show strong agreement and are reflective of illness severity in children with septic shock. As such, isolated FC measurement does not appear to provide added information relative to TC in acutely ill children with septic shock.

Meat qualities in the sheep with special reference to Scottish breeds and crosses. I

1939 ◽  
Vol 29 (4) ◽  
pp. 544-626 ◽  
Author(s):  
H. Pálsson
Keyword(s):  
Scientific Basis ◽  
Accurate Estimate ◽  
Quantitative Composition ◽  
Carcass Quality ◽  
Strongly Correlated ◽  
Precise Measure ◽  
Total Fat ◽  
Highly Correlated ◽  
High Degree ◽  
The Relationship

1. By establishing the relationship between linear carcass measurements and the quantitative composition of the carcass in terms of bone, muscle and fat, we have provided a scientific basis for the use of many measurements hitherto only presumed to provide an index to carcass quality.2. External carcass measurements are correlated with weight of the skeleton. The most useful for this purpose are length of tibia + tarsus and length of the fore-cannon.3. As indices of muscle, external measures are only of indirect value. Thus, both F – T and G/F × 100 are strongly correlated with weight of muscle as a percentage of skeletal weight.4. Similarly, F provides an index of fat, being negatively correlated with fat as a percentage of bone.5. For muscle and fat internal measures permit a more precise estimate to be made. A + B is the best index of the former while C + J + Y provide the most accurate estimate of the weight of fat.6. Still better indices for muscle and fat are provided by suitable combinations of external and internal measurements. Thus L/10 + A + B is very highly correlated with the weight of muscle, and L/10 × (C + J + Y) is the best index of fat in the hoggets. For bone, a most efficient single index is shown to be the weight of the fore-cannon bone.7. The weight of the skeleton can be estimated with a high degree of accuracy from the weight of the bones in either one leg or loin. Both these joints combined, however, provide a still better estimate.8. The muscle in one leg or loin + leg provides an excellent index of the weight of muscle in the whole carcass.9. The fat in one leg, loin, or both these joints combined provides a good index of the weight of the total fat in the carcass. Both joints combined give the most precise measure.10. The value of certain measurements which are not necessarily associated with the quantity of the major tissues of the carcass, but which nevertheless have important qualitative significance, is emphasized.

scholarly journals Socioeconomic development and agricultural intensification in Mato Grosso

2013 ◽  
Vol 368 (1619) ◽  
pp. 20120168 ◽  
Author(s):  
Leah K. VanWey ◽  
Stephanie Spera ◽  
Rebecca de Sa ◽  
Dan Mahr ◽  
John F. Mustard
Keyword(s):  
Agricultural Production ◽  
Agricultural Intensification ◽  
Socioeconomic Development ◽  
Commodity Markets ◽  
Strongly Correlated ◽  
Mato Grosso ◽  
Multiple Indicators ◽  
Double Cropping ◽  
The Relationship ◽  
Investments In Education

The Brazilian agro-industrial frontier in Mato Grosso rapidly expanded in total area of mechanized production and in total value of production in the last decade. This article shows the spatial pattern of that expansion from 2000 to 2010, based on novel analyses of satellite imagery. It then explores quantitatively and qualitatively the antecedents and correlates of intensification, the expansion of the area under two crops per year. Double cropping is most likely in areas with access to transportation networks, previous profitable agricultural production, and strong existing ties to national and international commodity markets. The article concludes with an exploration of the relationship between double cropping and socioeconomic development, showing that double cropping is strongly correlated with incomes of all residents of a community and with investments in education. We conclude that double cropping in Mato Grosso is very closely tied to multiple indicators of socioeconomic development.

scholarly journals The Relationship Between Vertical Loadrates and Tibial Acceleration Across Footstrike Patterns

2018 ◽  
Vol 3 (3) ◽  
pp. 2473011418S0020 ◽  
Author(s):  
Irene Davis ◽  
Todd Hayano ◽  
Adam Tenforde
Keyword(s):  
Impact Loading ◽  
Ground Reaction Force ◽  
Reaction Force ◽  
Force Plate ◽  
Correlation Coefficients ◽  
Strongly Correlated ◽  
Vertical Ground Reaction Force ◽  
Vertical Ground ◽  
Tibial Acceleration ◽  
The Relationship

Category: Other Introduction/Purpose: While the etiology of injuries is multifactorial, impact loading, as measured by the loadrate of the vertical ground reaction force has been implicated. These loadrates are typically measured with a force plate. However, this limits the measure of impacts to laboratory environments. Tibial acceleration, another measure of running impacts, is considered a surrogate for loadrate. It can be measured using new wearable technology that can be used in a runner’s natural environment. However, the correlation between tibial acceleration measured from mobile devices and vertical ground reaction force loadrates, measured from forceplates, is unknown. The purpose of this study was to determine the correlation between vertical and resultant loadrates to vertical and resultant tibial acceleration across different footstrike patterns (FSP) in runners. Methods: The study involved a sample of convenience made up of 169 runners (74 F, 95 M; age: 38.66±13.08 yrs) presenting at a running injury clinic. This included 25 habitual forefoot strike (FFS), 17 midfoot strike (MFS) and 127 rearfoot strike (RFS) runners. Participants ran on an instrumented treadmill (average speed 2.52±0.25 m/s), with a tri-axial accelerometer attached at the left distal medial tibia. Only subjects running with pain <3/10 on a VAS scale during the treadmill run were included to reduce the confounding effect of pain. Vertical average, vertical instantaneous and resultant instantaneous loadrates (VALR, VILR and RILR) and peak vertical and resultant tibial accelerations (VTA, RTA) were averaged for 8 consecutive left steps. Correlation coefficients (r) were calculated between tibial accelerations and loadrates. Results: All tibial accelerations were significantly correlated across all loadrates, with the exception of RTA with VILR for FFS (Table 1) which was nearly significant (p=0.068). Correlations ranged from 0.37-0.82. VTA was strongly correlated with all loadrates (r = 0.66). RTA was also strongly correlated with both loadrates for RFS and MFS, but only moderately correlated with loadrates for FFS (r = 0.47). Correlations were similar across the different loadrates (VALR, VILR, RILR). Conclusion: The stronger correlation between vertical tibial acceleration and all loadrates (VALR, VILR, RILR) suggests that it may be the best surrogate for loadrates when studying impact loading in runners.

scholarly journals General Psychopathology, Cognition, and the Cerebral Cortex in 10-Year-Old Children: Insights From the Adolescent Brain Cognitive Development Study

2022 ◽  
Vol 15 ◽  
Author(s):  
Yash Patel ◽  
Nadine Parker ◽  
Giovanni A. Salum ◽  
Zdenka Pausova ◽  
Tomáš Paus
Keyword(s):  
Cerebral Cortex ◽  
Cognitive Development ◽  
Surface Area ◽  
Cortical Surface ◽  
Strongly Correlated ◽  
General Psychopathology ◽  
Cortical Surface Area ◽  
Neurite Density ◽  
The Relationship ◽  
Strength Of Association

General psychopathology and cognition are likely to have a bidirectional influence on each other. Yet, the relationship between brain structure, psychopathology, and cognition remains unclear. This brief report investigates the association between structural properties of the cerebral cortex [surface area, cortical thickness, intracortical myelination indexed by the T1w/T2w ratio, and neurite density assessed by restriction spectrum imaging (RSI)] with general psychopathology and cognition in a sample of children from the Adolescent Brain Cognitive Development (ABCD) study. Higher levels of psychopathology and lower levels of cognitive ability were associated with a smaller cortical surface area. Inter-regionally—across the cerebral cortex—the strength of association between an area and psychopathology is strongly correlated with the strength of association between an area and cognition. Taken together, structural deviations particularly observed in the cortical surface area influence both psychopathology and cognition.

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