Staphylococcus aureus skin colonization is mediated by SasG lectin variation

Staphylococcus aureus causes the majority of skin and soft tissue infections, but this pathogen only transiently colonizes healthy skin. However, this transient skin exposure enables S. aureus to transition to infection. The initial adhesion of S. aureus to skin corneocytes is mediated by surface protein G (SasG). Here, phylogenetic analyses reveal the presence of two major divergent SasG alleles in S. aureus: SasG-I and SasG-II. Structural analyses of SasG-II identify a nonaromatic arginine in the binding pocket of the lectin subdomain that mediates adhesion to corneocytes. Atomic force microscopy and corneocyte adhesion assays indicate that SasG-II can bind to a broader variety of ligands than SasG-I. Glycosidase treatment results in different binding profiles between SasG-I and SasG-II on skin cells. In addition, SasG-mediated adhesion is recapitulated using differentiated N/TERT keratinocytes. Our findings indicate that SasG-II has evolved to adhere to multiple ligands, conferring a distinct advantage to S. aureus during skin colonization.

Trait variation in patchy landscapes: Morphology of spotted salamanders (Ambystoma maculatum) varies more within ponds than between ponds

The influence of intraspecific trait variation on species interactions makes trait-based approaches critical to understanding eco-evolutionary processes. Because species occupy habitats that are patchily distributed in space, species interactions are influenced not just by the degree of intraspecific trait variation but also the relative proportion of trait variation that occurs within- versus between-patches. Advancement in trait-based ecology hinges on understanding how trait variation is distributed within and between habitat patches across the landscape. We sampled larval spotted salamanders (Ambystoma maculatum) across six spatially discrete ponds to quantify within- and between-pond variation in mass, length, and various metrics associated with their relationship (scaling, body condition, shape). Across all traits, within-pond variation contributed more to total observed morphological variation than between-pond variation. Between-pond variation was not negligible, however, and explained 20-41% of total observed variation in measured traits. Between-pond variation was more pronounced in salamander tail morphology compared to head or body morphology, suggesting that pond-level factors more strongly influence tails than other body parts. We also observed differences in mass-length relationships across ponds, both in terms of scaling slopes and intercepts, though differences in the intercepts were much stronger. Preliminary evidence hinted that newly constructed ponds were a driver of the observed differences in mass-length relationships and morphometrics. General pond-level difference in salamander trait covariation suggest that allometric scaling of morphological traits is context dependent in patchy landscapes. Effects of pond age offer the hypothesis that habitat restoration through pond construction is a driver of variation in trait scaling, which managers may leverage to bolster trait diversity.

Staphylococcus aureus skin colonization is mediated by SasG lectin variation

Staphylococcus aureus causes the majority of skin and soft tissue infections, but this pathogen only transiently colonizes healthy skin. However, this transient skin exposure enables S. aureus to transition to infection. Initial adhesion of S. aureus to skin corneocytes is mediated by surface protein G (SasG). Here, phylogenetic analyses reveal the presence of two major divergent SasG alleles in S. aureus, SasG-I and SasG-II. Structural analyses of SasG-II identified a unique non-aromatic arginine in the binding pocket of the lectin subdomain that mediates adhesion to corneocytes. Atomic force microscopy and corneocyte adhesion assays indicated SasG-II can bind to a broader variety of ligands than SasG-I. Glycosidase treatment resulted in different binding profiles between SasG-I and SasG-II on skin cells. Additionally, SasG-mediated adhesion was recapitulated using differentiated N/TERT keratinocytes. Our findings indicate that SasG-II has evolved to adhere to multiple ligands, conferring a distinct advantage to S. aureus during skin colonization.

Repeated Emergence of Variant TetR Family Regulator, FarR, and Increased Resistance to Antimicrobial Unsaturated Fatty Acid among Clonal Complex 5 Methicillin-Resistant Staphylococcus aureus

Resistance-nodulation-division (RND) superfamily efflux pumps promote antibiotic resistance in Gram-negative pathogens, but their role in Gram-positive pathogens, including methicillin-resistant Staphylococcus aureus (MRSA) is undocumented. However, recent in vitro selections for resistance of S. aureus to an antimicrobial fatty acid, linoleic acid, and an antibiotic, rhodomyrtone, identified H121Y and C116R substitution variants, respectively, in a TetR family regulator, FarR, promoting increased expression of the RND pump FarE. Hypothesizing that in vivo selection pressures have also promoted the emergence of FarR variants, we searched available genome data and found that strains with FarR^H121Y from human and bovine hosts have emerged sporadically in clonal complexes (CCs) CC1, CC30, CC8, CC22, and CC97, whereas multiple FarR variants have occurred within CC5 hospital-associated (HA)-MRSA. Of these, FarR^E160G and FarR^E93EE were exclusive to CC5, while FarR^C116Y, FarR^P165L, and FarR^G166D also occurred in nonrelated CCs, primarily from bovine hosts. Within CC5, FarR^C116Y and FarR^G166D strains were polyphyletic, each exhibiting two emergence events. FarR^C116Y and FarR^E160G were individually sufficient to confer increased expression of FarE and enhanced resistance to linoleic acid (LA). Isolates with FarR^E93EE were most closely related to S. aureus N315 MRSA and exhibited increased resistance independently of FarR^E93EE. Accumulation of pseudogenes and additional polymorphisms in FarR^E93EE strains contributed to a multiresistance phenotype which included fosfomycin and fusidic acid resistance in addition to increased linoleic acid resistance. These findings underscore the remarkable adaptive capacity of CC5 MRSA, which includes the polyphyletic USA100 lineage of HA-MRSA that is endemic in the Western hemisphere and known for the acquisition of multiple resistance phenotypes.

Adaptation to chronic drought modifies soil microbial community responses to phytohormones

Drought imposes stress on plants and associated soil microbes, inducing coordinated adaptive responses, which can involve plant-soil signalling via phytohormones. However, we know little about how microbial communities respond to phytohormones, or how these responses are shaped by chronic (long-term) drought. Here, we added three phytohormones (abscisic acid, 1-aminocyclopropane-1-carboxylic acid, and jasmonic acid) to soils from long-term (25-year), field-based climate treatments to test the hypothesis that chronic drought alters soil microbial community responses to plant stress signalling. Phytohormone addition increased soil respiration, but this effect was stronger in irrigated than in droughted soils and increased soil respiration at low phytohormone concentrations could not be explained by their use as substrate. Thus, we show that drought adaptation within soil microbial communities modifies their responses to phytohormone inputs. Furthermore, distinct phytohormone-induced shifts in microbial functional groups in droughted vs. irrigated soils might suggest that drought-adapted soil microorganisms perceive phytohormones as stress-signals, allowing them to anticipate impending drought.

Abundance of montane salamanders over an elevational gradient

Climate change is expected to systematically alter the distribution and population dynamics of species around the world. The effects are expected to be particularly strong at high latitudes and elevations, and for ectothermic species with small ranges and limited movement potential, such as salamanders in the southern Appalachian Mountains. In this study, we sought to establish baseline abundance estimates for plethodontid salamanders (family: Plethodontidae) over an elevational gradient in Great Smoky Mountains National Park. In addition to generating these baseline data for multiple species, we describe methods for surveying salamanders that allow for meaningful comparisons over time by separating observation and ecological processes generating the data. We found that Plethodon jordani had a mid-elevation peak (1,500 m) in abundance and Desmognathus wrighti increased in abundance with elevation up to the highest areas of the park (2025 m), whereas Eurycea wilderae increased in abundance up to 1,600 m and then plateaued with increasing uncertainty. Litter depth, herbaceous ground cover, and proximity to stream were also important predictors of abundance (dependent upon species), whereas daily temperature, precipitation, ground cover, and humidity influenced detection rates. Our data provide some of the first minimally biased information for future studies to assess changes in the abundance and distribution of salamanders in this region. Understanding abundance patterns along with detailed baseline distributions will be critical for comparisons with future surveys to understand the population and community-level effects of climate change on montane salamanders.

Predicted alteration of surface activity as a consequence of climate change

Wildlife are faced with numerous threats to survival, none more pressing than that of climate change. Understanding how species will respond behaviorally, physiologically, and demographically to a changing climate is a cornerstone of many contemporary ecological studies, especially for organisms, such as amphibians, whose persistence is closely tied to abiotic conditions. Activity is a useful parameter for understanding the effects of climate change because activity is directly linked to fitness as it dictates foraging times, energy budgets, and mating opportunities. However, activity can be challenging to measure directly, especially for secretive organisms like plethodontid salamanders, which only become surface active when conditions are cool and moist because of their anatomical and physiological restrictions. We estimated abiotic predictors of surface activity for the seven species of the Plethodon jordani complex. Five independent data sets collected from 2004 to 2017 were used to determine the parameters driving salamander surface activity in the present day, which were then used to predict potential activity changes over the next 80 yrs. Average active seasonal temperature and vapor pressure deficit were the strongest predictors of salamander surface activity and, without physiological or behavioral modifications, salamanders were predicted to exhibit a higher probability of surface activity during peak active season under future climate conditions. Temperatures during the active season likely do not exceed salamander thermal maxima to cause activity suppression and, until physiological limits are reached, future conditions may continue to increase activity. Our model is the first comprehensive field-based study to assess current and future surface activity probability. Our study provides insights into how a key behavior driving fitness may be affected by climate change.

Author Correction: Tropical forest soil carbon stocks do not increase despite 15 years of doubled litter inputs

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Tropical forest soil carbon stocks do not increase despite 15 years of doubled litter inputs

Soil organic carbon (SOC) dynamics represent a persisting uncertainty in our understanding of the global carbon cycle. SOC storage is strongly linked to plant inputs via the formation of soil organic matter, but soil geochemistry also plays a critical role. In tropical soils with rapid SOC turnover, the association of organic matter with soil minerals is particularly important for stabilising SOC but projected increases in tropical forest productivity could trigger feedbacks that stimulate the release of stored SOC. Here, we demonstrate limited additional SOC storage after 13-15 years of experimentally doubled aboveground litter inputs in a lowland tropical forest. We combined biological, physical, and chemical methods to characterise SOC along a gradient of bioavailability. After 13 years of monthly litter addition treatments, most of the additional SOC was readily bioavailable and we observed no increase in mineral-associated SOC. Importantly, SOC with weak association to soil minerals declined in response to long-term litter addition, suggesting that increased plant inputs could modify the formation of organo-mineral complexes in tropical soils. Hence, we demonstrate the limited capacity of tropical soils to sequester additional C inputs and provide insights into potential underlying mechanisms.

Detritus Quality and Locality Determines Survival and Mass, but Not Export, of Wood Frogs at Metamorphosis

Single-site experiments have demonstrated detritus quality in wetlands can have strongly negative, neutral, and even positive influences on wildlife. However, an examination of the influence of detritus quality across several regions is lacking and can provide information on whether impacts from variation in detritus quality are consistent across species with wide ranges. To address this gap in regional studies we examined effects of emergent and allochthonous detritus of different nutrient qualities on amphibians and assessed a mechanism that may contribute to potential impacts. We used aquatic mesocosms to raise wood frogs (Rana sylvatica) from two regions of the United States with whole plants from purple loosestrife (Lythrum salicaria), leaf litter from native hardwood trees, and a mixture of both. We examined several metrics of amphibian fitness and life history, including survival, number of days to metamorphosis, and size at metamorphosis. Further, we quantified whether the effects of detritus type could translate to variation in anuran biomass or standing stock of nitrogen or phosphorus export. Our results show detritus with high nutrient quality (purple loosestrife) negatively influenced survival of wood frogs, but increased size of metamorphic individuals in two different regions of the United States. Despite the decrease in survival, the increase in size of post-metamorphic anurans raised with high quality detritus resulted in anuran biomass and standing stock of N and P export being similar across treatments at both locations. These results further demonstrate the role of plant quality in shaping wetland ecosystem dynamics, and represent the first demonstration that effects are consistent within species across ecoregional boundaries.

Climate change and shrinking salamanders: alternative mechanisms for changes in plethodontid salamander body size

An increasing number of studies have demonstrated relationships between climate trends and body size change of organisms. In many cases, climate might be expected to influence body size by altering thermoregulation, energetics or food availability. However, observed body size change can result from a variety of ecological processes (e.g. growth, selection, population dynamics) or imperfect observation of biological systems. We used two extensive datasets to evaluate alternative mechanisms for recently reported changes in the observed body size of plethodontid salamanders. We found that mean adult body size of salamanders can be highly sensitive to survey conditions, particularly rainfall. This systematic bias in the detection of larger or smaller individuals could result in a signature of body size change in relation to reported climate trends when it is simply observation error. We also identify considerable variability in body size distributions among years and find that individual growth rates can be strongly influenced by weather. Finally, our study demonstrates that measures of mean adult body size can be highly variable among surveys and that large sample sizes may be required to make reliable inferences. Identifying the effects of climate change is a critical area of research in ecology and conservation. Researchers should be aware that observed changes in certain organisms can result from multiple ecological processes or systematic bias due to nonrandom sampling of populations.

Environmental relative moldiness index and associations with home characteristics and infant wheeze

Possible relationships between mold contamination, as described by the Environmental Relative Moldiness Index (ERMI), home characteristics, and the development of wheeze in the first year of life were evaluated among a cohort of urban infants (n = 103) in Syracuse, New York. Pregnant women with a history of asthma were recruited in 2001-2002 for the "Assessment of Urban Dwellings for Indoor Toxics" (AUDIT) study. When the infants were approximately 3 months of age, a home inspection was carried out and indoor environmental samples collected, including vacuumed house dust. ERMI levels in the Syracuse cohort homes were higher than the U.S. average, with an overall mean of 11.4. ERMI levels were significantly higher in homes with visible water problems (p = 0.023) and visible mold (p = 0.023). ERMI levels in apartments were significantly lower than the values measured in houses (p = 0.0003). While infants experiencing wheeze (38%) tended to live in homes with higher ERMI values than those without wheeze (ERMI values of 12.3 and 10.9, respectively), the differences did not reach statistical significance. A subset analysis limited to infants with living room samples who remained in the same home during the study (n = 25) was suggestive of an association between higher ERMI values and wheeze (p = 0.10). In summary, the ERMI is a standardized metric which allows for comparison of moldiness levels in homes across studies and regions in the United States. ERMI levels in Syracuse homes were skewed to the high end of the national scale. Higher ERMI levels were indicators of water problems, mold, and type of housing.

Abstract P3-15-08: A multicenter observational study to investigate the relationship between physician-assessed febrile neutropenia (FN) risk and prediction model FN or SN (severe neutropenia) risk in patients with breast cancer

Background: A prediction model was previously developed to estimate the risk of SN or FN during the first cycle of chemotherapy, taking into account both the myelotoxicity of the chemotherapy regimen and the interplay of specific tumor and patient characteristics (Lyman, 2011). This model may potentially be useful for predicting which patients are at greatest risk for developing neutropenic complications, particularly among those patients receiving intermediate FN risk chemotherapy regimens, where the influence of patient characteristics becomes a critical consideration. To assess the clinical utility of this model, physicians assessed FN risk in patients with non-myeloid malignancies, and then physician-assessed FN risk was compared to prediction model risk.

Methods: This was a prospective, multicenter, observational study (124 community-based oncologists, 944 patients). Analysis of a breast cancer subgroup (93 oncologists, 364 patients) is reported here. Patients were eligible if they were: ≥18 years old, newly diagnosed, and candidates for initiating a new course of chemotherapy using an NCCN intermediate (10-20%) FN risk chemotherapy regimen. Oncologists entered clinical data about the patient into the model; they also made a clinical prediction of FN risk. Oncologists were blinded to both the data elements collected by the model and the risk predicted by the model. Data were only collected until the chemotherapy order was written; no outcome data were collected. The primary objective was to investigate the relationship between physician-assessed FN risk and prediction model SN or FN risk. As an exploratory endpoint, physicians were asked to estimate FN risk on the same set of four hypothetical case studies with varying FN risk factors. The correlation between risk probability scores was estimated as well as a 95% confidence interval accounting for intra-physician correlation. A smooth spline curve was fit to show the average relationship between physician-assessed and prediction model risk probability scores.

Results: Most patients were planning to receive TC (54%) and most had stage I-II disease (71%). Median (min, max) age was 58 years (23, 83). Physician-assessed FN risk correlated weakly with prediction model FN or SN risk: correlation 0.166 (95% CI: 0.027, 0.298). There was wide variability among all 124 physicians in their assessment of FN risk for the four case studies (Q1, Q3 case study 1: 20%, 40%; case study 2: 10%, 18%; case study 3: 20%, 40%; case study 4: 25%, 60%).

Conclusions: This study suggests that community oncologists would benefit from the use of an automated system for assessing FN risk among those receiving intermediate risk chemotherapy regimens. Such a system would help oncologists identify the patients who would benefit most from clinical intervention and help improve practice efficiency and quality of care.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P3-15-08.

Levels of household particulate matter and environmental tobacco smoke exposure in the first year of life for a cohort at risk for asthma in urban Syracuse, NY

The Syracuse, NY, AUDIT (Assessment of Urban Dwellings for Indoor Toxics) study was designed to quantify asthma agent levels in the inner-city homes of a birth cohort whose mothers had a diagnosis of asthma. Risk of exposure to particulate matter (PM), particle number and tobacco smoke was assessed in 103 infants' homes. Repeat measurements were made in 44% of the homes. Infants also were examined on a quarterly basis during the first year of life to monitor their respiratory health and urine cotinine levels. Overall geometric mean (GM) values for PM(2.5) of 21.2 μg/m(3) and for PM(10) of 31.8 μg/m(3) were recorded in homes at visit 1. GM values for PM(2.5) and PM(10) in smoking homes were higher at 26.3 and 37.7 μg/m(3), while values in non-smoking homes were 12.7 and 21.2 μg/m(3) respectively. Fifty-four percent of mothers (55/103) smoked at some point in pregnancy (39% smoked throughout pregnancy). Environmental tobacco smoke (ETS) exposure occurred in 68% of homes during the infants' first year. Significant to this study was the size- and time-resolved monitoring of PM at 140 home visits and the classification of PM count data. PM number counts ranged from continuously low levels (little indoor activity) to continuously high counts (constant indoor activity), and recorded apparent instances of prolonged repeated cigarette smoking. Wheezing in the first year of life was recorded for 38% of the infants (39/103). Adjusted logistic regression modeling demonstrated that elevated levels of indoor PM(2.5) (≥ 15 μg/m(3)) were a significant risk factor for infant wheezing after controlling for infant gender, mothers' age and education level, season of home visit and presence of carpeting (OR 4.21; 95% CI 1.36-13.03; p=0.013). An elevated level of the nicotine metabolite cotinine in infant urine also was associated with infant wheezing after adjusting for infant gender, mothers' age and education level (OR 5.10; 95% CI 0.96-27.24; p=0.057). ETS exposure was pervasive in the AUDIT cohort and a risk for developing infants in this urban population.

Estimation of core terrestrial habitat for stream-breeding salamanders and delineation of riparian buffers for protection of biodiversity

Many species of wildlife depend on riparian habitats for various life-history functions (e.g., breeding, foraging, overwintering). Although this unique habitat is critical for many species, delineations of riparian zones and buffers for various taxa are lacking. Typically when buffer zones are determined to mitigate edge effects, they are based on criteria that protect aquatic resources alone and do not consider impacts to wildlife and other terrestrial resources. Using two different survey methods (area-constrained daytime searches and nighttime visual encounter searches), we estimated core terrestrial habitat and buffer widths for stream-breeding salamanders in southern Appalachian streams from May to August 2004. A core terrestrial habitat of 27.0 m encompassed 95% of the salamander assemblage (four species of stream plethodontids), and an additional 50 m (to buffer edge effects) yielded a total buffer of 77.0 m. When each species of the assemblage was analyzed separately, the maximum core terrestrial habitat needed for the Blue Ridge two-lined salamander (Eurycea wilderae), a dominant member and the farthest-ranging species from the stream, was 42.6 m. Thus, we recommend an overall buffer width of 92.6 m in southern Appalachian streams. To protect stream amphibians and other wildlife dependent on riparian areas, land managers and policy makers must consider conserving more than aquatic resources alone. Developing core terrestrial habitat estimates and buffer zone widths for wildlife populations is a critical first step in the conservation of many semiaquatic organisms and protecting biodiversity.

NORMAL HEMATOLOGIC AND BIOCHEMICAL VALUES FOR PRELAYING GREATER SAGE GROUSE (CENTROCERCUS UROPHASIANUS) AND THEIR INFLUENCE ON CHICK SURVIVAL

Declines in greater sage grouse (Centrocercus urophasianus) productivity and population numbers throughout their range demand a better understanding of how nutrition influences sage grouse populations. During March and April 1999-2001, blood samples were collected from 158 female (73 adult, 85 yearling), free-ranging, prelaying, greater sage grouse from an area in northwestern Nevada, USA, and southeastern Oregon, USA. These blood samples were evaluated to establish normal blood values for sage grouse and ascertain if certain blood parameters, as indices of nutrition, are useful for predicting if sage grouse hens would raise at least one chick to 1 August. Results of logistic regression indicated that three of six blood parameters analyzed--glucose, total plasma protein, and calcium: phosphorus ratio-affected the probability of a female sage grouse raising at least one chick to late summer. Ranking of the standardized estimates revealed that glucose and total plasma protein had the greatest impact on the likelihood of a female successfully raising chicks. Odds ratios indicated that a 1-unit increase in glucose (1 mg/dl) and plasma protein (0.1 g/dl) would result in a 4% and 113% positive increase, respectively, in the predicted odds of at least one chick surviving until 1 August. Odds ratios for calcium : phosphorus ratio revealed a 70% decline in the predicted odds of at least one chick surviving until 1 August if the level of this parameter increased one unit (e.g., 3:1 to 4:1). Based on these analyses, values of some blood parameters used as indices of nutrition, especially glucose, total plasma protein, and calcium : phosphorus ratio, can be successfully used to predict reproductive success of sage grouse. These parameters are not only indicative of the nutritional status of prelaying hens but may be associated with nutritional quality of the habitat and therefore have important management significance.

Second-generation recombination-based in vivo expression technology for large-scale screening for Vibrio cholerae genes induced during infection of the mouse small intestine

We have constructed an improved recombination-based in vivo expression technology (RIVET) and used it as a screening method to identify Vibrio cholerae genes that are transcriptionally induced during infection of infant mice. The improvements include the introduction of modified substrate cassettes for resolvase that can be positively and negatively selected for, allowing selection of resolved strains from intestinal homogenates, and three different tnpR alleles that cover a range of translation initiation efficiencies, allowing identification of infection-induced genes that have low-to-moderate basal levels of transcription during growth in vitro. A transcriptional fusion library of 8,734 isolates of a V. cholerae El Tor strain that remain unresolved when the vibrios are grown in vitro was passed through infant mice, and 40 infection-induced genes were identified. Nine of these genes were inactivated by in-frame deletions, and their roles in growth in vitro and fitness during infection were measured by competition assays. Four mutant strains were attenuated >10-fold in vivo compared with the parental strain, demonstrating that infection-induced genes are enriched in genes essential for virulence.

An activator of glutamate decarboxylase genes regulates the expression of enteropathogenic Escherichia coli virulence genes through control of the plasmid-encoded regulator, Per

Enteropathogenic Escherichia coli (EPEC) is a major cause of infantile diarrhoea in a number of developing countries and is the prototype of pathogenic bacteria that cause attaching and effacing (A/E) intestinal lesions. A chromosomal pathogenicity island, termed the locus of enterocyte effacement (LEE), contains all the genes necessary for the A/E phenotype as well as genes for a type III secretion system and intimate adhesion. Genes in the LEE and genes involved in the synthesis of bundle-forming pili (BFP) are positively regulated by the plasmid-encoded regulator (Per) and comprise the per regulon. In order to identify factors that control the per regulon, we screened an EPEC genomic library for clones that modulate the expression of per. A plasmid clone that decreased the expression of per was isolated using a lacZ reporter gene fused to the per promoter. Subcloning revealed that YhiX, a putative AraC/XylR family transcriptional regulator, was the effector of per repression. Through downregulation of per, a plasmid overproducing YhiX reduced the synthesis of intimin, BfpA, Tir, and CesT, factors important for EPEC virulence. yhiX is located downstream of gadA, which encodes glutamate decarboxylase, an enzyme involved in acid resistance of E. coli. YhiX was found to be an activator of gadA, and the cloned yhiX gene increased production of glutamate decarboxylases (GAD) and activated the transcription of the gadA and gadB promoters. Therefore, yhiX was renamed gadX. Analysis of a gadX mutant grown in the different culture media with acidic and alkaline pH showed that regulation of perA, gadA and gadB by GadX was altered by the external pH and the culture media condition. Under conditions in which EPEC infects cultured epithelial cells, GadX negatively regulated perA expression, and the derepression in the gadX mutant increased translocation of Tir into epithelial cells relative to wild-type EPEC. DNA mobility shift experiments showed that purified GadX protein bound to the perA, gadA and gadB promoter regions in vitro, indicating that GadX is a transcriptional regulator of these genes. On the basis of these results, we propose that GadX may be involved in the appropriate expression of genes required for acid resistance and virulence of EPEC. Our data are consistent with a model in which environmental changes resulting from passage from the stomach to the proximal small intestine induce the functional effect of GadX on per and GAD expression in order to prevent inappropriate expression of the products of these two systems.

Activation of enteropathogenic Escherichia coli (EPEC) LEE2 and LEE3 operons by Ler

Enteropathogenic Escherichia coli (EPEC) produces attaching and effacing lesions (AE) on epithelial cells. The genes involved in the formation of the AE lesions are contained within a pathogenicity island named the locus of enterocyte effacement (LEE). The LEE comprises 41 open reading frames organized in five major operons: LEE1, LEE2, LEE3, LEE4 and tir. The first gene of the LEE1 operon encodes a transcription activator of the other LEE operons that is called the LEE-encoded regulator (Ler). The LEE2 and LEE3 operons are divergently transcribed with overlapping -10 promoter regions, and gene fusion studies have shown that they are both activated by Ler. Deletion analysis, using lacZ reporter fusions, of the LEE2 and LEE3 promoters demonstrated that deletions extending closer to the LEE2 transcription start site than -247 bp lead to loss of activation by Ler, whereas only 70 bp upstream of the LEE3 transcription start site is required for Ler-mediated activation. We have purified Ler as a His-tagged protein and used it to perform DNA-binding assays with LEE2 and LEE3. We observed that Ler bound to a DNA fragment containing the -300 to +1 region of LEE2; however, it failed to bind to a DNA fragment containing the -300 to +1 region of LEE3, suggesting that Ler activates both operons by only binding to the regulatory region upstream of LEE2. The Ler-activatable LEE3:lacZ fusions extended to what would be -246 bp of the LEE2 operon. A lacZ fusion from the -300 to +1 region of LEE3 failed to be activated by Ler, consistent with our hypothesis that Ler activates the expression of LEE2 and LEE3 by binding to a region located downstream of the LEE3 transcription start site. DNase I footprinting revealed that Ler protected a region of 121 bp upstream of LEE2. Purified Ler mutated in the coiled-coil domain was unable to activate transcription and to bind to the LEE2 regulatory region. These data indicate that Ler may bind as a multimer to LEE2 and activate both divergent operons by a novel mechanism potentially involving changes in the DNA structure.

Men's perspectives on individual and family coping with their wives' breast cancer and chemotherapy

Little research has examined the impact of cancer and chemotherapy treatment for breast cancer from men's perspectives as partners, fathers, and caregivers. This research, part of a larger study describing women's, partners', and children's perspectives, aims to describe men's perspectives on their experiences and how their wives' breast cancer and chemotherapy impacted them and their families, to describe what facilitated and hindered their coping, and to suggest interventions to assist men and their families to manage the experience with less stress. This participatory action study used qualitative naturalistic inquiry methods. Semistructured interviews were conducted with 11 male partners. Two major themes were identified: focusing on a wife's illness and care, and focusing on the family to keep life going. Nine sub-themes cut across the major themes: being there, relying on health care professionals, being informed and contributing to decision making, trying to keep patterns normal and family life going, helping out and relying on others, being positive, putting self on hold, adapting work life, and managing finances.

Virulence gene regulation inside and outside

Much knowledge about microbial gene regulation and virulence is derived from genetic and biochemical studies done outside of hosts. The aim of this review is to correlate observations made in vitro and in vivo with two different bacterial pathogens in which the nature of regulated gene expression leading to virulence is quite different. The first is Vibrio cholerae, in which the concerted action of a complicated regulatory cascade involving several transcription activators leads ultimately to expression of cholera toxin and the toxin-coregulated pilus. The regulatory cascade is active in vivo and is also required for maintenance of V. cholerae in the intestinal tract during experimental infection. Nevertheless, specific signals predicted to be generated in vivo, such as bile and a temperature of 37 degrees C, have a severe down-modulating effect on activation of toxin and pilus expression. Another unusual aspect of gene regulation in this system is the role played by inner membrane proteins that activate transcription. Although the topology of these proteins suggests an appealing model for signal transduction leading to virulence gene expression, experimental evidence suggests that such a model may be simplistic. In Streptococcus pyogenes, capsule production is critical for virulence in an animal model of necrotizing skin infection. Yet capsule is apparently produced to high levels only from mutation in a two-component regulatory system, CsrR and CsrS. Thus it seems that in V. cholerae a complex regulatory pathway has evolved to control virulence by induction of gene expression in vivo, whereas in S. pyogenes at least one mode of pathogenicity is potentiated by the absence of regulation.

Molecular cloning and transcriptional regulation of ompT, a ToxR-repressed gene in Vibrio cholerae

In pathogenic Vibrio cholerae, at least 17 genes are co-ordinately regulated by ToxR. Most of these genes, including those that encode cholera toxin (CT), toxin co-regulated pilus (TCP), accessory colonization factor (ACF) and OmpU, are positively regulated. OmpT is the only identified protein under negative regulation of ToxR. To understand the molecular mechanism by which ToxR represses OmpT expression, we cloned ompT and characterized the ompT promoter and its interaction with ToxR. Sequence analysis revealed that ompT encodes a predicted 35.8 kDa outer membrane porin of V. cholerae. Primer extension analysis identified a transcriptional start site 104 bp upstream of the translational start codon. Both primer extension analysis and promoter fusion studies showed that ToxR represses OmpT expression at the transcriptional level. Promoter fusion studies also suggest that cyclic AMP receptor protein (CRP) is involved in ompT activation. Gel mobility shift assays combined with DNase I footprinting analysis demonstrated that ToxR mediates repression of ompT transcription by directly binding to an A/T-rich region between -95 and -30 of the ompT promoter. To further understand how the interaction of ToxR with different promoters results in its function as an activator or repressor, we have also mapped the regions on the ctxAB and toxT promoters to which ToxR binds. The regions protected by ToxR on each of these promoters are all A/T rich and large in size, although they are positioned differently relative to each transcriptional start site.

Analysis of ToxR-dependent transcription activation of ompU, the gene encoding a major envelope protein in Vibrio cholerae

The membrane proteins ToxR and ToxS regulate a variety of genes associated with the virulence of Vibrio cholerae, the agent of human cholera. One of the ToxRS-regulated genes is the ompU gene, which encodes a porin that may also act as an adhesin. To begin to understand the mechanism of ompU transcription activation by ToxRS, we performed genetic and biochemical studies on the ompU promoter. Deletions with a 5' end-point at or downstream of -128, relative to the start site for transcription, did not direct expression of a lacZ reporter gene in wild-type V. cholerae, although the -128 promoter fragment did direct ToxRS-dependent reporter gene activity under conditions of ToxR overexpression in E. coli. Consistent with the activation data is that membranes containing ToxR and ToxS caused a gel electrophoretic mobility shift when mixed at low concentrations with deletion fragments whose end-point is at -211, but not with -128 or -68 fragments. ToxRS membranes did shift the -128 fragment when added at higher concentrations. DNase I footprinting analysis of ompU promoter DNA complexed with ToxRS membranes demonstrated protection of three sites: an upstream site ranging from -238 to -139, and two downstream sites ranging from -116 to -58 and -53 to -24. Within the DNA protected from DNase I digestion by ToxRS membranes, there are no elements bearing similarity to those identified previously within the promoters of two other ToxR-dependent genes, ctxA and toxT. We suggest a model for transcription activation that involves sequential ToxR-binding events to distinct regions in the ompU promoter.

Neural expression of a novel alternatively spliced and polyadenylated Gs alpha transcript

We have isolated an alternative transcript of the rat Gs alpha signal transduction protein gene, referred to as Gs alpha N1. Gs alpha N1 was isolated by differential hybridization screening of genes induced upon dexamethasone treatment of the neuronal-like CA77 rat thyroid C-cell line. The 1-kilobase Gs alpha N1 transcript is generated by alternative splicing and polyadenylation of a novel terminal exon. This exon lies 800 base pairs downstream of exon 3 in the Gs alpha gene. Dexamethasone differentially induced Gs alpha N1 severalfold relative to Gs alpha mRNA in the CA77 cells, similar to the bias seen with alternative processing of the calcitonin/calcitonin gene-related peptide transcript. In addition to the differential regulation by dexamethasone, the expression pattern of Gs alpha N1 in rat tissues differed markedly from Gs alpha. Gs alpha N1 mRNA was much more abundant in the brain, with intermediate levels in skeletal muscle and very low levels in other tissues. This was in contrast to the more ubiquitously expressed Gs alpha mRNA. Within the brain, Gs alpha N1 was particularly abundant in discrete regions of the brainstem and hypothalamus that modulate autonomic functions. Examination of rat embryos demonstrated that Gs alpha is expressed in both brain and nonneural tissue at least 1 day before Gs alpha N1 mRNA could be detected in the embryonic brain. Based on the regulated expression of the Gs alpha N1 transcript and previous studies on G alpha proteins, the predicted Gs alpha N1 protein may potentially modulate several heterotrimeric G protein functions in the nervous system.

Cognitive effects of childhood leukemia therapy: a case for four specific deficits

Prophylactic treatment of the central nervous system (CNS) with cranial irradiation and antineoplastic drugs has made childhood acute lymphoblastic leukemia (ALL) a survivable disease, but at the same time there have been many reports of iatrogenic effects, including deficits in cognitive functioning. Previous research suggests a particular effect on the Freedom from Distractibility factor of the WISC-R, memory, and attention. These particular abilities are tested in a group of 43 ALL survivors, with comparisons against solid tumor as well as sibling controls. The results indicate that four cognitive processes are affected by CNS prophylaxis for ALL: short-term memory, speed of processing, visuomotor coordination, and sequencing ability. Younger children have a more severe speed of processing deficit and children treated with a less rigorous protocol appear to be slightly less affected generally. The specific cognitive deficits found are related to neurological evidence on both theoretical and empirical grounds. Results suggest that children who have received CNS prophylaxis are able to learn, but may be slower to acquire new material and may benefit from bimodal presentation.

Helminths of California quail (Callipepla californica) and mountain quail (Oreortyx pictus) in western Oregon

Eighty California quail (Callipepla californica), collected from the E. E. Wilson Wildlife Area near Monmouth, Oregon (USA) during a 22 mo period, were examined for gastrointestinal helminths. Eight birds were infected with three species of nematodes, Heterakis isolonche, Dispharynx nasuta, and Capillaria sp., and two species of cestodes, Rhabdometra odiosa and Davainea sp. Except for D. nasuta, prevalence did not exceed 5% despite mesic conditions in the collection area. Two mountain quail (Oreortyx pictus) were collected from Lane County, Oregon (USA), near Blue River Reservoir; both were infected with the nematode Trichostrongylus tenuis.

Prevalence of poxvirus in a population of California quail from Oregon, 1975-1987

Prevalences of poxvirus in a population of California quail (Callipepla californica) at the E. E. Wilson Wildlife Area, Oregon, were determined from 1982 through 1987 and compared with previously published results on prevalences in this population from 1975 to 1979. Poxvirus was present in 19 of 89 quail collected. Prevalences ranged from 6% for immature females to 41% for immature males. Prevalences were lowest during summer and fall and highest in winter and spring. Differences in the seasonal prevalences may be related to the seasonal dispersion pattern of quail.

Poxvirus in scaled quail and prevalences of poxvirus-like lesions in northern bobwhites and scaled quail from Texas

Prevalences of poxvirus-like lesions were determined for 177 northern bobwhites (Colinus virginianus) and 24 scaled quail (Callipepla squamata) trapped in southern Texas from 1976 to 1979 and for 190 northern bobwhites and 105 scaled quail shot at five locations in southern Texas from 1980 to 1981. None of the northern bobwhites trapped in 1976-1977 was infected, but 54% of the trapped scaled quail were infected; 17% of the northern bobwhites and 34% of the scaled quail shot in 1980-1981 had pox lesions, primarily on the wings. Prevalence was unrelated to sex or age of birds. For both species, prevalence was greatest during late spring and early summer. Histologic and electron microscopic examination confirmed poxvirus in two scaled quail, which constituted the first report of poxvirus in this species.