Blacklegged Tick (\u3cem\u3eIxodes scapularis\u3c/em\u3e) Distribution in Maine, USA, as Related to Climate Change, White-tailed Deer, and the Landscape

Lyme disease is caused by the bacterial spirochete Borrelia burgdorferi, which is transmitted through the bite of an infected blacklegged (deer) tick (Ixodes scapularis). Geographic invasion of I. scapularis in North America has been attributed to causes including 20th century reforestation and suburbanization, burgeoning populations of the white-tailed deer (Odocoileus virginianus) which is the primary reproductive host of I. scapularis, tick-associated non-native plant invasions, and climate change. Maine, USA, is a high Lyme disease incidence state, with a history of increasing I. scapularis abundance and northward range expansion. This thesis addresses the question: “To what extent has the range expansion of blacklegged ticks in Maine been associated with climate change, deer, and other factors?” using a long-term, passive surveillance dataset (1990-2013) of I. scapularis in Maine. Chapter 1 characterized temporal trends in I. scapularis submissions rate (an index of abundance) and phenology, in Maine’s northern (7 counties) versus southern (9 counties) tier. In the northern tier the I. scapularis submission rate and season duration increased throughout the duration of the time series, indicating I. scapularis was emergent but not established. By contrast, in the southern tier, submissions rate and season duration increased initially but after about 13 years leveled off, indicating I. scapularis was established by the mid-2000s. Winter and fall average minimum temperatures increased in the northern tier and summer relative humidity in both tiers increased. I. scapularis submission rates and phenological changes were correlated with relative humidity statewide. Generally, I. scapularis submission rates and phenological changes were correlated with winter warming, but predominantly in the northern tier and only the early half of the time series for the southern tier. Though northern tier climate appears to have become more permissive over time, current ecological suitability for I. scapularis in the northern tier may be limited due to low deer densities, which averaged ~5/mi2. In the southern tier, deer densities were higher and correlated with I. scapularis submissions rate. However, a number of other, unknown population-limiting mechanisms could have been operating to keep I. scapularis in the southern tier at a dynamic equilibrium since the mid-2000s. Also observed was a correlation between Lyme incidence and I. scapularis in the northern but not southern tier. This may represent decoupling of reported disease incidence and entomological risk as measured simply by tick abundance and Borrelial infection prevalence. This discrepancy suggested that disease discovery had increased through greater clinician and patient awareness and testing effort, and/or that acarological risk may be a more nuanced function of diverse, variously virulent strain types in multiple pathogens borne by I. scapularis. Chapter 2 used a generalized additive mixed model (GAMM) to model linear and nonlinear relationships between nymphal I. scapularis abundance and predictors, while allowing for spatiotemporal dependencies within and among wildlife management districts. I. scapularis nymphs increased with increasing deer densities up to ~13 deer/mi2, but beyond this threshold tick abundance did not vary with deer density. This result corroborated the idea of a saturating relationship between I. scapularis and deer density. It was also consistent with empirical studies suggesting deer density must be lowered below ~8-13/mi2 to lower I. scapularis abundance enough to lower Lyme disease. The model also indicated that more ticks were associated with higher relative humidity, warmer minimum winter temperatures and more degree-day accumulation, and that without deer \u3e4/mi2 warmer winters would not increase nymphal abundance. The Maine Department of Inland Fisheries and Wildlife northern tier goals range from 10-15/mi2 and southern tier goals from 15-20/mi2 for 2030 (MEIFW 2017). We recommended deer densities be kept to ≤10/mi2 in all of Maine’s northern tier to mitigate likely increases in ticks due to future warming. Suburbanization and presence of tick-associated non-native plants did not enter the model because they co-occurred with deer. Chapter 3 ascertained that Lyme incidences on the off-shore, unbridged islands of Maine have been above the statewide average and at least on par with those seen on other offshore islands in Massachusetts and Rhode Island. Increasing I. scapularis abundance and Lyme incidence have been attributed to high deer densities by some residents of these island communities. Burgeoning deer densities on some of these islands have led to various deer management histories along with a good deal of conflict on how to manage deer populations. We summarized the burden of Lyme disease, entomological risk, and deer management histories on these islands. We also polled island residents in 2016 to quantify the level of concern about the Lyme disease problem and assess the level of support for deer herd reduction on their islands. A 2016 survey of island residents indicated that other deer-related problems, namely vehicle collisions and garden and forest damage, motivated support for deer reduction as much as Lyme disease. We recommended efforts to keep deer density ≤15/mi2 and to remove invasive plant species--particular Japanese barberry—from the landscape. The benefits of these measures will extend beyond vector tick control to improved deer and forest health

Increasing Actual and Perceived Burden of Tick-Borne Disease in Maine

Introduction: The burden of tick-borne disease (TBD) in Maine has steadily increased since the first case of Lyme disease was reported in the late 1980s. The emergence of five different agents of TBD in Maine has been challenging and confusing for clinicians and the public. Methods: We reviewed the ecology of emerging of tick -borne disease, then reviewed risk factors for tick bites and tick-borne disease in Maine. We then compared the burden of TBD versus community-acquired comparison infections in terms of hospitalizations, deaths, and media attention. Results and Discussion: In Maine, risk of exposure to bites from the vector blacklegged or “deer tick”, Ixodes scapularis, is a reality in most of the state. In New England, resurgence of white-tailed deer attending reforestation and suburbanization of the landscape and climate change have contributed to geographic expansion of the deer tick from relict populations in southern New England. TBDs have emerged as a significant health burden in Maine, but compared with other infections of public health importance, receive disproportionately high media attention. Measures of tick-borne disease severity provide a necessary context for individual and public health decision making. Mass media reports and social networking inform much public debate regarding TBDs, but in many instances, do not accurately reflect their actual prevalence or expected outcome. Conclusion: Reducing actual and perceived risks associated with TBD will require well-supported information paired with an appreciation for how interpersonal communication and social media drive community perceptions and responses to the emergence of TBDs

History of Deer Herd Reduction for Tick Control on Maine’s Offshore Islands

The incidence of Lyme disease in Maine is associated with high abundance of blacklegged (deer) ticks, which in turn has been partly attributed to local overabundance of white-tailed deer. With evidence from Monhegan Island that the complete removal of deer reduced ticks and risk of contracting Lyme disease, nine other offshore communities initiated efforts to cull deer. We reviewed and summarized available histories of deer management on Maine’s offshore islands. Concern about Lyme disease provided the overarching impetus for deer culls. Culls mostly occurred on islands that have no regular firearms hunting season, island communities have been challenged to control deer numbers, and social acceptance of deer culls varied. Integrated tick management (ITM) is the key to controlling ticks, but statewide ITM policy is lacking. Formation of vector control districts with statewide ITM policy would support all communities in Maine

Mobile methane measurements: effects of instrument specifications on data interpretation, reproducibility, and isotopic precision

Recent research has used mobile methane (CH4) measurements to identify and quantify emissions, but the effect of instrument response time on concentration measurements is rarely considered. Furthermore, stable isotope ratios are increasingly used in mobile measurements to attribute sources, but the precision of mobile isotopic measurements depend on a combination of instrument and measurement conditions. Here we tested the effect of instrument speed on concentration measurements by outfitting a vehicle with isotopic and concentration-only gas analysers with different response times and conducting multiple mobile surveys. Additionally, we performed a sensitivity analysis for the isotopic precision achievable under different conditions by programming a physical model, validated with empirical data from our mobile surveys. We found that slower response time led to a greater underestimation of measured CH4 concentration, during both driving and stationary measurements, while the area under peaks in concentration is consistent and provides a robust means of comparing data between instruments. We also explore the use of an algorithm to improve instrument response. Our sensitivity analysis showed that the precision of isotopic measurements increases with the concentration range and the duration of the measurement following a power law. Our findings have important implications for the reporting and comparability of results between surveys with different instrumental setups and provide a framework for optimising sampling strategies under given objectives, conditions, and instrument capabilities

Follicular CD4 T Helper Cells As a Major HIV Reservoir Compartment: A Molecular Perspective

Effective antiretroviral therapy (ART) has prevented the progression to AIDS and reduced HIV-related morbidities and mortality for the majority of infected individuals. However, a lifelong administration of ART is necessary, placing an inordinate burden on individuals and public health systems. Therefore, discovering therapeutic regimens able to eradicate or functionally cure HIV infection is of great importance. ART interruption leads to viral rebound highlighting the establishment and maintenance of a latent viral reservoir compartment even under long-term treatment. Follicular helper CD4 T cells (TFH) have been reported as a major cell compartment contributing to viral persistence, consequent to their susceptibility to infection and ability to release replication-competent new virions. Here, we discuss the molecular profiles and potential mechanisms that support the role of TFH cells as one of the major HIV reservoirs

Characterization of subsurface media from locations up- and down-gradient of a uranium-contaminated aquifer.

The processing of sediment to accurately characterize the spatially-resolved depth profiles of geophysical and geochemical properties along with signatures of microbial density and activity remains a challenge especially in complex contaminated areas. This study processed cores from two sediment boreholes from background and contaminated core sediments and surrounding groundwater. Fresh core sediments were compared by depth to capture the changes in sediment structure, sediment minerals, biomass, and pore water geochemistry in terms of major and trace elements including pollutants, cations, anions, and organic acids. Soil porewater samples were matched to groundwater level, flow rate, and preferential flows and compared to homogenized groundwater-only samples from neighboring monitoring wells. Groundwater analysis of nearby wells only revealed high sulfate and nitrate concentrations while the same analysis using sediment pore water samples with depth was able to suggest areas high in sulfate- and nitrate-reducing bacteria based on their decreased concentration and production of reduced by-products that could not be seen in the groundwater samples. Positive correlations among porewater content, total organic carbon, trace metals and clay minerals revealed a more complicated relationship among contaminant, sediment texture, groundwater table, and biomass. The fluctuating capillary interface had high concentrations of Fe and Mn-oxides combined with trace elements including U, Th, Sr, Ba, Cu, and Co. This suggests the mobility of potentially hazardous elements, sediment structure, and biogeochemical factors are all linked together to impact microbial communities, emphasizing that solid interfaces play an important role in determining the abundance of bacteria in the sediments

The Rewiring of Ubiquitination Targets in a Pathogenic Yeast Promotes Metabolic Flexibility, Host Colonization and Virulence

Funding: This work was funded by the European Research Council [http://erc.europa.eu/], AJPB (STRIFE Advanced Grant; C-2009-AdG-249793). The work was also supported by: the Wellcome Trust [www.wellcome.ac.uk], AJPB (080088, 097377); the UK Biotechnology and Biological Research Council [www.bbsrc.ac.uk], AJPB (BB/F00513X/1, BB/K017365/1); the CNPq-Brazil [http://cnpq.br], GMA (Science without Borders fellowship 202976/2014-9); and the National Centre for the Replacement, Refinement and Reduction of Animals in Research [www.nc3rs.org.uk], DMM (NC/K000306/1). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Acknowledgments We thank Dr. Elizabeth Johnson (Mycology Reference Laboratory, Bristol) for providing strains, and the Aberdeen Proteomics facility for the biotyping of S. cerevisiae clinical isolates, and to Euroscarf for providing S. cerevisiae strains and plasmids. We are grateful to our Microscopy Facility in the Institute of Medical Sciences for their expert help with the electron microscopy, and to our friends in the Aberdeen Fungal Group for insightful discussions.Peer reviewedPublisher PD

Microbial Community Dynamics of Lactate Enriched Hanford Groundwaters

The Department of Energy site at Hanford, WA, has been historically impacted by U and Cr from the nuclear weapons industry. In an attempt to stimulate microbial remediation of these metals, in-situ lactate enrichment experiments are ongoing. In order to bridge the gap from the laboratory to the field, we inoculated triplicate anaerobic, continuous-flow glass reactors with groundwater collected from well Hanford 100-H in order to obtain a stable, enriched community while selecting for metal-reducing bacteria. Each reactor was fed from a single carboy containing defined media with 30 mM lactate at a rate of 0.223 ml/min under continuous nitrogen flow at 9 ml/min. Cell counts, organic acids, gDNA (for qPCR and pyrosequencing) and gases were sampled during the experiment. Cell counts remained low (less than 1x107 cells/ml) during the first two weeks of the experiment, but by day 20, had reached a density greater than 1x108 cells/ml. Metabolite analysis showed a decrease in the lactate concentrations over time. Pyruvate concentrations ranged from 20-40 uM the first week of the experiment then was undetectable after day 10. Likewise, formate appeared in the reactors during the first week with concentrations of 1.48-1.65 mM at day 7 then the concentrations decreased to 0.69-0.95 on day 10 and were undetectable on day 15. Acetate was present in low amounts on day 3 (0.15-0.33 mM) and steadily increased to 3.35-5.22 mM over time. Similarly, carbon dioxide was present in low concentrations early on and increased to 0.28-0.35 mM as the experiment progressed. We also were able to detect low amounts of methane (10-20 uM) during the first week of the experiment, but by day 10 the methane was undetectable. From these results and pyrosequencing analysis, we conclude that a shift in the microbial community dynamics occurred over time to eventually form a stable and enriched microbial community. Comprehensive investigations such as these allow for the examination of not only which nutrient source will accelerate site remediation, but also provide insight to evaluate remediation strategies through which enriched community members are important for bioremediation

Selenoprotein gene nomenclature

The human genome contains 25 genes coding for selenocysteine-containing proteins (selenoproteins). These proteins are involved in a variety of functions, most notably redox homeostasis. Selenoprotein enzymes with known functions are designated according to these functions: TXNRD1, TXNRD2, and TXNRD3 (thioredoxin reductases), GPX1, GPX2, GPX3, GPX4 and GPX6 (glutathione peroxidases), DIO1, DIO2, and DIO3 (iodothyronine deiodinases), MSRB1 (methionine-R-sulfoxide reductase 1) and SEPHS2 (selenophosphate synthetase 2). Selenoproteins without known functions have traditionally been denoted by SEL or SEP symbols. However, these symbols are sometimes ambiguous and conflict with the approved nomenclature for several other genes. Therefore, there is a need to implement a rational and coherent nomenclature system for selenoprotein-encoding genes. Our solution is to use the root symbol SELENO followed by a letter. This nomenclature applies to SELENOF (selenoprotein F, the 15 kDa selenoprotein, SEP15), SELENOH (selenoprotein H, SELH, C11orf31), SELENOI (selenoprotein I, SELI, EPT1), SELENOK (selenoprotein K, SELK), SELENOM (selenoprotein M, SELM), SELENON (selenoprotein N, SEPN1, SELN), SELENOO (selenoprotein O, SELO), SELENOP (selenoprotein P, SeP, SEPP1, SELP), SELENOS (selenoprotein S, SELS, SEPS1, VIMP), SELENOT (selenoprotein T, SELT), SELENOV (selenoprotein V, SELV) and SELENOW (selenoprotein W, SELW, SEPW1). This system, approved by the HUGO Gene Nomenclature Committee, also resolves conflicting, missing and ambiguous designations for selenoprotein genes and is applicable to selenoproteins across vertebrates