Host Genotype Links to Salivary and Gut Microbiota by Periodontal Status.

Limited evidence describing how host genetic variants affect the composition of the microbiota is currently available. The aim of this study was to assess the associations between a set of candidate host genetic variants and microbial composition in both saliva and gut in the TwinsUK registry. A total of 1,746 participants were included in this study and provided stool samples. A subset of 1,018 participants also provided self-reported periodontal data, and 396 of those participants provided a saliva sample. Host DNA was extracted from whole-blood samples and processed for Infinium Global screening array, focusing on 37 selected single-nucleotide polymorphisms (SNPs) previously associated with periodontitis. The gut and salivary microbiota of participants were profiled using 16S ribosomal RNA amplicon sequencing. Associations between genotype on the selected SNPs and microbial outcomes, including α diversity, ß diversity, and amplicon sequence variants (ASVs), were investigated in a multivariate mixed model. Self-reported periodontal status was also compared with microbial outcomes. Downstream analyses in gut microbiota and salivary microbiota were carried out separately. IL10 rs6667202 and VDR 2228570 SNPs were associated with salivary α diversity, and SNPs in IL10, HSA21, UHRF2, and Fc-γR genes were associated with dissimilarity matrix generated from salivary ß diversity. The SNP that was associated with the greatest number of salivary ASVs was VDR 2228570 followed by IL10 rs6667202, and that of gut ASVs was NPY rs2521364. There were 77 salivary ASVs and 39 gut ASVs differentially abundant in self-reported periodontal disease versus periodontal health. The dissimilarity between saliva and gut microbiota within individuals appeared significantly greater in self-reported periodontal cases compared to periodontal health. IL10 and VDR gene variants may affect salivary microbiota composition. Periodontal status may drive variations in the salivary microbiota and possibly, to a lesser extent, in the gut microbiota.

Diet and irritable bowel syndrome: an update from a UK consensus meeting.

There has been a renewed interest in the role of dietary therapies to manage irritable bowel syndrome (IBS), with diet high on the agenda for patients. Currently, interest has focussed on the use of traditional dietary advice (TDA), a gluten-free diet (GFD) and the low FODMAP diet (LFD). A consensus meeting was held to assess the role of these dietary therapies in IBS, in Sheffield, United Kingdom.Evidence for TDA is from case control studies and clinical experience. Randomised controlled trials (RCT) have demonstrated the benefit of soluble fibre in IBS. No studies have assessed TDA in comparison to a habitual or sham diet. There have been a number of RCTs demonstrating the efficacy of a GFD at short-term follow-up, with a lack of long-term outcomes. Whilst gluten may lead to symptom generation in IBS, other components of wheat may also play an important role, with recent interest in the role of fructans, wheat germ agglutinins, as well as alpha amylase trypsin inhibitors. There is good evidence for the use of a LFD at short-term follow-up, with emerging evidence demonstrating its efficacy at long-term follow-up. There is overlap between the LFD and GFD with IBS patients self-initiating gluten or wheat reduction as part of their LFD. Currently, there is a lack of evidence to suggest superiority of one diet over another, although TDA is more acceptable to patients.In view of this evidence, our consensus group recommends that dietary therapies for IBS should be offered by dietitians who first assess dietary triggers and then tailor the intervention according to patient choice. Given the lack of dietetic services, novel approaches such as employing group clinics and online webinars may maximise capacity and accessibility for patients. Further research is also required to assess the comparative efficacy of dietary therapies to other management strategies available to manage IBS.

Can one-step nucleic acid amplification assay predict four or more positive axillary lymph node involvement in breast cancer patients: a single-centre retrospective study.

BACKGROUND: One-step nucleic acid amplification (OSNA) assay is a proven, accurate, intraoperative method for the detection of lymph node (LN) metastases. The aim of this study was to assess if the total tumour load (TTL) as calculated by OSNA could be used to predict N2 stage disease, ie ≥4 LN containing metastases, in invasive breast cancer patients. METHODS: Between 2011 and 2019 at St Richard's Hospital, Chichester, all macro-metastasis-positive OSNA cases for invasive breast cancer were retrospectively reviewed. The association between clinicopathological variables and ≥4 LNs containing metastases was analysed using regression analysis. RESULTS: In total, 134 patients with positive sentinel lymph node (SLN) on OSNA undergoing axillary node clearance were analysed, 53% of whom had no further positive LN, 25% had ≥4 lymph nodes positive. TTL was calculated as the aggregate of cytokeratin-19 mRNA copy count of all SLN tissue analysed via OSNA. TTL ≥1.1×105copies/µl and lymphovascular invasion (LVI) were both significant predictors of N2 stage disease on both univariate (TTL p=0.04, LVI p=0.005) and multivariate (TTL p=0.008, LVI p=0.039) regression analysis. CONCLUSION: Our findings show that SLN TTL via intraoperative OSNA assay can predict four or more positive axillary LN involvement in invasive breast cancer. This is important in that it may be used intraoperatively by surgeons to decide on whether to proceed with a full axillary node clearance in order to stage the axilla. Further research is required to shape future guidance.

Diagnostic value of cutaneous manifestation of SARS-CoV-2 infection.

BACKGROUND: One of the challenging aspects of SARS-CoV-2 infection is its diverse multisystemic disease presentation. OBJECTIVES: To evaluate the diagnostic value of cutaneous manifestations of SARS-CoV-2 infection and investigate their duration and timing in relation to other COVID-19 symptoms. METHODS: We used data from 336 847 UK users of the COVID Symptom Study app to assess the diagnostic value of body rash or an acral rash in SARS-CoV-2 infection, and data from an independent online survey of 11 544 respondents to investigate skin-specific symptoms and collect their photographs. RESULTS: Using data from the app, we show significant association between skin rashes and a positive swab test result (odds ratio 1·67, 95% confidence interval 1·42-1·97). Strikingly, among the respondents of the independent online survey, we found that 17% of SARS-CoV-2-positive cases reported skin rashes as the first presentation, and 21% as the only clinical sign of COVID-19. Together with the British Association of Dermatologists, we have compiled a catalogue of images of the most common skin manifestations of COVID-19 from 400 individuals (https://covidskinsigns.com), which we have made publicly available to assist clinicians in recognition of this early clinical feature of COVID-19. CONCLUSIONS: Skin rashes cluster with other COVID-19 symptoms, are predictive of a positive swab test, and occur in a significant number of cases, either alone or before other classical symptoms. Recognizing rashes is important in identifying new and earlier cases of COVID-19.

The Urinary Tract Microbiome in Older Women Exhibits Host Genetic and Environmental Influences.

The urinary microbiome is a relatively unexplored niche that varies with gender. Urinary microbes, especially in aging populations, are associated with morbidity. We present a large-scale study exploring factors defining urinary microbiome composition in community-dwelling older adult women without clinically active infection. Using 1,600 twins, we estimate the contribution of genetic and environmental factors to microbiome variation. The urinary microbiome is distinct from nearby sites and unrelated to stool microbiome with more Actinobacteria, Fusobacteria and Proteobacteria, but fewer Bacteroidetes, Firmicutes and Verrumicrobia. A quarter of variants had heritability estimates greater than 10% with most heritable microbes having potential clinical relevance, including Escherichia-Shigella linked to urinary tract infections. Age, menopausal status, prior UTI, and host genetics were top factors defining the urobiome with increased microbial diversity tending to associate with older age. These findings highlight the distinct composition of the urinary microbiome and significant contributions of host genetics.

Evolution of ungulate mating systems: Integrating social and environmental factors.

Ungulates exhibit diverse mating systems that range from monogamous pair territories to highly polygynous leks. We review mating systems and behaviors across ungulates and offer a new approach synthesizing how interacting factors may shape those mating systems. Variability exists in mating systems among and within species of ungulates and likely is affected by predation risk, availability of resources (food and mates), habitat structure, and sociality. Ungulate mating systems may be labile as a consequence of the varying strength of those interacting factors. In addition, degree of polygyny and sexual dimorphism in size are associated with the evolution of mating systems. Neither male-male combat nor paternal care, however, can completely explain differences in sexual size dimorphism for ungulates, a necessary component in understanding the development of some mating systems. Whatever the evolutionary pathway, sexual segregation limits paternal care allowing more intense male-male competition. Selection of habitat structure, because it modifies risk of predation, is a major determinant of sociality for ungulates. Likewise, ruggedness and steepness of terrain limit the types of mating systems that can occur because of limitations in group size and cohesiveness, as well as the ability of males to herd even small groups of females effectively. The quality and defensibility of resources affect mating systems, as does the defensibility of females. Population density of females also may be a critical determinant of the types of mating systems that develop. Size of groups likewise constrains the types of mating tactics that males can employ. Our aim was to use those relationships to create a broad conceptual model that predicts how various environmental and social factors interact to structure mating systems in ungulates. This model provides a useful framework for future tests of the roles of both ecological and social conditions in influencing the social systems of ungulates.

rKIN: Kernel-based method for estimating isotopic niche size and overlap.

The isotopic niche of consumers represents biologically relevant information on resource and habitat use. Several tools have been developed to quantify niche size and overlap. Nonetheless, methods adapted by spatial ecologists to quantify animal home ranges can be modified for use in stable isotope ecology when data are not normally distributed in bivariate space. We offer a tool that draws on existing spatial metrics, such as minimum convex polygon (MCP) and standard ellipse area (SEA), and add novel metrics using kernel utilization density (KUD) estimators to measure isotopic niche size and overlap. We present examples using empirical and simulated data to demonstrate the performance of the package kernel isotopic niches in r (rKIN) under various scenarios. Results of niche size from MCP, SEA and KUD were highly correlated but divergent among datasets. Overall, the KUD method produced the largest niche sizes and was more sensitive to the distribution of the isotopic data. Pairwise estimates of overlap were highly variable, likely because MCP and SEA inherently include or exclude unused areas in the resulting niche estimate. Four bandwidth methods (reference, normal scale, plug-in and biased cross-validation) produced comparable estimates of niche size and overlap at various sample sizes (10-40). Niche size and overlap were consistent across sample sizes >15. Use of rKIN will allow isotope ecologists to quantify niche shifts, expansions or contractions, as well as assess the performance of several estimation methods. The package also can be applied to other data types (e.g. principal component analysis, multi-dimensional scaling) so long as axes and measurement units are identical and can be converted to Cartesian coordinates.

Habitat use and social mixing between groups of resident and augmented bighorn sheep.

Monitoring dispersal, habitat use, and social mixing of released ungulates is crucial for successful translocation and species conservation. We monitored 127 female bighorn sheep (Ovis canadensis) released in three populations from 2000 to 2009 to investigate if augmented bighorns expanded and shifted seasonal ranges, used different habitat compared with resident females, and if animals mixed socially. Augmented bighorns in all populations expanded range use compared with residents by shifting utilization distributions. Size of utilization distributions, however, were smaller for augmented females compared with residents in all areas except one. Overlap of seasonal utilization distributions between augmented and resident bighorns and use of slope and elevation differed across populations. In two populations, differences in size and overlap of seasonal utilization distributions and use of slope and elevation supported the hypothesis that habitat use of bighorns in their source area influenced their habitat use after release. Mixing between resident and augmented adult females occurred on average during only 21% of sightings and was similar across populations. Our results clarify how augmented bighorns mix with resident animals and how habitat use is modified following augmentations. Such information is needed to improve bighorn sheep augmentations and can be applied to augmentations of other ungulates.

Hunting and mountain sheep: Do current harvest practices affect horn growth?

The influence of human harvest on evolution of secondary sexual characteristics has implications for sustainable management of wildlife populations. The phenotypic consequences of selectively removing males with large horns or antlers from ungulate populations have been a topic of heightened concern in recent years. Harvest can affect size of horn-like structures in two ways: (a) shifting age structure toward younger age classes, which can reduce the mean size of horn-like structures, or (b) selecting against genes that produce large, fast-growing males. We evaluated effects of age, climatic and forage conditions, and metrics of harvest on horn size and growth of mountain sheep (Ovis canadensis ssp.) in 72 hunt areas across North America from 1981 to 2016. In 50% of hunt areas, changes in mean horn size during the study period were related to changes in age structure of harvested sheep. Environmental conditions explained directional changes in horn growth in 28% of hunt areas, 7% of which did not exhibit change before accounting for effects of the environment. After accounting for age and environment, horn size of mountain sheep was stable or increasing in the majority (~78%) of hunt areas. Age-specific horn size declined in 44% of hunt areas where harvest was regulated solely by morphological criteria, which supports the notion that harvest practices that are simultaneously selective and intensive might lead to changes in horn growth. Nevertheless, phenotypic consequences are not a foregone conclusion in the face of selective harvest; over half of the hunt areas with highly selective and intensive harvest did not exhibit age-specific declines in horn size. Our results demonstrate that while harvest regimes are an important consideration, horn growth of harvested male mountain sheep has remained largely stable, indicating that changes in horn growth patterns are an unlikely consequence of harvest across most of North America.

British Dietetic Association systematic review and evidence-based practice guidelines for the dietary management of irritable bowel syndrome in adults (2016 update).

BACKGROUND: The first British Dietetic Association (BDA) guidelines for the dietary management of irritable bowel syndrome (IBS) in adults were published in 2012. Subsequently, there has been a wealth of new research. The aim of this work was to systematically review the evidence for the role of diet in the management of IBS and to update the guidelines. METHODS: Twelve questions relating to diet and IBS were defined based on review of the previous guideline questions, current evidence and clinical practice. Chosen topics were on healthy eating and lifestyle (alcohol, caffeine, spicy food, elimination diets, fat and fluid intakes and dietary habits), milk and dairy, dietary fibre, fermentable carbohydrates, gluten, probiotics and elimination diets/food hypersensitivity. Data sources were CINAHL, Cochrane Register of Controlled Trials, Embase, Medline, Scopus and Web of Science up to October 2015. Studies were assessed independently in duplicate using risk of bias tools specific to each included study based on inclusion and exclusion criteria for each question. National Health and Medical Research Council grading evidence levels were used to develop evidence statements and recommendations, in accordance with Practice-based Evidence in Nutrition Global protocol used by the BDA. RESULTS: Eighty-six studies were critically appraised to generate 46 evidence statements, 15 clinical recommendations and four research recommendations. The IBS dietary algorithm was simplified to first-line (healthy eating, provided by any healthcare professional) and second-line [low FODMAP (fermentable oligosaccharides, disaccharides, monosaccharides and polyols) to be provided by dietitian] dietary advice. CONCLUSIONS: These guidelines provide updated comprehensive evidence-based details to achieve the successful dietary management of IBS in adults.

Linking habitat selection to fitness-related traits in herbivores: the role of the energy landscape.

Animals may partially overcome environmental constraints on fitness by behaviorally adjusting their exposure to costs and supplies of energy. Few studies, however, have linked spatiotemporal variation in the energy landscape to behaviorally mediated measures of performance that ostensibly influence individual fitness. We hypothesized that strength of selection by North American elk (Cervus elaphus) for areas that reduced costs of thermoregulation and activity, and increased access to high-quality forage, would influence four energetically mediated traits related to fitness: birth mass of young, nutritional condition of adult females at the onset of winter, change in nutritional condition of females between spring and winter, and neonatal survival. We used a biophysical model to map spatiotemporally explicit costs of thermoregulation and activity experienced by elk in a heterogeneous landscape. We then combined model predictions with data on forage characteristics, animal locations, nutritional condition, and mass and survival of young to evaluate behaviorally mediated effects of the energy landscape on fitness-related traits. During spring, when high-quality forage was abundant, female elk that consistently selected low-cost areas before parturition gave birth to larger young than less-selective individuals, and birth mass had a strong, positive influence on probability of survival. As forage quality declined during autumn, however, lactating females that consistently selected the highest quality forage available accrued more fat and entered winter in better condition than less-selective individuals. Results of our study highlight the importance of understanding the dynamic nature of energy landscapes experienced by free-ranging animals.

Sexual segregation in North American elk: the role of density dependence.

We investigated how density-dependent processes and subsequent variation in nutritional condition of individuals influenced both timing and duration of sexual segregation and selection of resources. During 1999-2001, we experimentally created two population densities of North American elk (Cervus elaphus), a high-density population at 20 elk/km(2), and a low-density population at 4 elk/km(2) to test hypotheses relative to timing and duration of sexual segregation and variation in selection of resources. We used multi-response permutation procedures to investigate patterns of sexual segregation, and resource selection functions to document differences in selection of resources by individuals in high- and low-density populations during sexual segregation and aggregation. The duration of sexual segregation was 2 months longer in the high-density population and likely was influenced by individuals in poorer nutritional condition, which corresponded with later conception and parturition, than at low density. Males and females in the high-density population overlapped in selection of resources to a greater extent than in the low-density population, probably resulting from density-dependent effects of increased intraspecific competition and lower availability of resources.

Migrating mule deer: effects of anthropogenically altered landscapes.

BACKGROUND: Migration is an adaptive strategy that enables animals to enhance resource availability and reduce risk of predation at a broad geographic scale. Ungulate migrations generally occur along traditional routes, many of which have been disrupted by anthropogenic disturbances. Spring migration in ungulates is of particular importance for conservation planning, because it is closely coupled with timing of parturition. The degree to which oil and gas development affects migratory patterns, and whether ungulate migration is sufficiently plastic to compensate for such changes, warrants additional study to better understand this critical conservation issue. METHODOLOGY/PRINCIPAL FINDINGS: We studied timing and synchrony of departure from winter range and arrival to summer range of female mule deer (Odocoileus hemionus) in northwestern Colorado, USA, which has one of the largest natural-gas reserves currently under development in North America. We hypothesized that in addition to local weather, plant phenology, and individual life-history characteristics, patterns of spring migration would be modified by disturbances associated with natural-gas extraction. We captured 205 adult female mule deer, equipped them with GPS collars, and observed patterns of spring migration during 2008-2010. CONCLUSIONS/SIGNIFICANCE: Timing of spring migration was related to winter weather (particularly snow depth) and access to emerging vegetation, which varied among years, but was highly synchronous across study areas within years. Additionally, timing of migration was influenced by the collective effects of anthropogenic disturbance, rate of travel, distance traveled, and body condition of adult females. Rates of travel were more rapid over shorter migration distances in areas of high natural-gas development resulting in the delayed departure, but early arrival for females migrating in areas with high development compared with less-developed areas. Such shifts in behavior could have consequences for timing of arrival on birthing areas, especially where mule deer migrate over longer distances or for greater durations.

Risk-sensitive allocation in seasonal dynamics of fat and protein reserves in a long-lived mammal.

Body reserves of numerous taxa follow seasonal rhythms that are a function of temporal patterns in food availability and life-history events; however, tests of the theory underlying the allocation of somatic reserves for long-lived organisms are rare, especially for free-ranging mammals. We evaluated the hypothesis that allocation of somatic reserves to survival (i.e., metabolic processes) and reproduction should be sensitive to current nutritional state relative to seasonal thresholds in those reserves. Our goal was to reveal the linkages between nutrition and life-history traits to understand how long-lived, iteroparous organisms balance the allocation of somatic reserves to reproduction, while retaining reserves as insurance for survival in unpredictable environments. Our evaluation was based on seasonal dynamics in fat (measured as ingesta-free body fat; IFBFat) and protein reserves (measured as ingesta-free, fat-free body mass; IFFFBMass) of 136 female mule deer (Odocoileus hemionus) over 8 years. Although mean changes in fat and protein reserves were positive over summer and negative over winter, accretion and catabolism of those reserves was not consistent among individuals. Over winter, both lipid and protein stores available in autumn were catabolized in proportion to their availability above a post-winter threshold (5·8% IFBFat, 33 kg IFFFBMass); however, lean body tissue was spared at the expense of lipid reserves. Female deer mostly synthesized lean body tissue over summer and committed post-winter fat reserves to reproduction relative to their availability above an autumn threshold (>8·6% IFBFat), which was lowered by 2·8 percentage points (pp) for each additional young recruited. Mothers reduced their autumn fat threshold to secure current reproductive investment and, thereby, endured a cost of reproduction at the expense of fat accumulation. Allocation of somatic reserves occurred in a risk-sensitive framework; females allocated reserves relative to their availability above seasonal thresholds. In contrast to current notions of summer accretion and winter catabolism of body reserves, some individuals deposited reserves over winter and catabolized reserves over summer, mainly because regulation of individual condition was state-dependent. Consequently, behaviour and life-history strategies may be as much a function of nutritional contributions of the previous season as of the current one.

Population density of North American elk: effects on plant diversity.

Large, herbivorous mammals have profound effects on ecosystem structure and function and often act as keystone species in ecosystems they inhabit. Density-dependent processes associated with population structure of large mammals may interact with ecosystem functioning to increase or decrease biodiversity, depending on the relationship of herbivore populations relative to the carrying capacity (K) of the ecosystem. We tested for indirect effects of population density of large herbivores on plant species richness and diversity in a montane ecosystem, where increased net aboveground primary productivity (NAPP) in response to low levels of herbivory has been reported. We documented a positive, linear relationship between plant-species diversity and richness with NAPP. Structural equation modeling revealed significant indirect relationships between population density of herbivores, NAPP, and species diversity. We observed an indirect effect of density-dependent processes in large, herbivorous mammals and species diversity of plants through changes in NAPP in this montane ecosystem. Changes in species diversity of plants in response to herbivory may be more indirect in ecosystems with long histories of herbivory. Those subtle or indirect effects of herbivory may have strong effects on ecosystem functioning, but may be overlooked in plant communities that are relatively resilient to herbivory.

Population structure and genetic diversity of moose in Alaska.

Moose (Alces alces) are highly mobile mammals that occur across arboreal regions of North America, Europe, and Asia. Alaskan moose (Alces alces gigas) range across much of Alaska and are primary herbivore consumers, exerting a prominent influence on ecosystem structure and functioning. Increased knowledge gained from population genetics provides insights into their population dynamics, history, and dispersal of these unique large herbivores and can aid in conservation efforts. We examined the genetic diversity and population structure of moose (n = 141) with 8 polymorphic microsatellites from 6 regions spanning much of Alaska. Expected heterozygosity was moderate (H(E) = 0.483-0.612), and private alleles ranged from 0 to 6. Both F(ST) and R(ST) indicated significant population structure (P < 0.001) with F(ST) < 0.109 and R(ST) < 0.125. Results of analyses from STRUCTURE indicated 2 prominent population groups, a mix of moose from the Yakutat and Tetlin regions versus all other moose, with slight substructure observed among the second population. Estimates of dispersal differed between analytical approaches, indicating a high level of historical or current gene flow. Mantel tests indicated that isolation-by-distance partially explained observed structure among moose populations (R(2) = 0.45, P < 0.01). Finally, there was no evidence of bottlenecks either at the population level or overall. We conclude that weak population structure occurs among moose in Alaska with population expansion from interior Alaska westward toward the coast.

Density-dependent effects on physical condition and reproduction in North American elk: an experimental test.

Density dependence plays a key role in life-history characteristics and population ecology of large, herbivorous mammals. We designed a manipulative experiment to test hypotheses relating effects of density-dependent mechanisms on physical condition and fecundity of North American elk (Cervus elaphus) by creating populations at low and high density. We hypothesized that if density-dependent effects were manifested principally through intraspecific competition, body condition and fecundity of females would be lower in an area of high population density than in a low-density area. Thus, we collected data on physical condition and rates of pregnancy in each experimental population. Our manipulative experiment indicated that density-dependent feedbacks affected physical condition and reproduction of adult female elk. Age-specific pregnancy rates were lower in the high-density area, although there were no differences in pregnancy of yearlings or in age at peak reproduction between areas. Age-specific rates of pregnancy began to diverge at 2 years of age between the two populations and peaked at 6 years old. Pregnancy rates were most affected by body condition and mass, although successful reproduction the previous year also reduced pregnancy rates during the current year. Our results indicated that while holding effects of winter constant, density-dependent mechanisms had a much greater effect on physical condition and fecundity than density-independent factors (e.g., precipitation and temperature). Moreover, our results demonstrated effects of differing nutrition resulting from population density during summer on body condition and reproduction. Thus, summer is a critical period for accumulation of body stores to buffer animals against winter; more emphasis should be placed on the role of spring and summer nutrition on population regulation in large, northern herbivores.

Nutritional development of feeding strategies in arctic ruminants: digestive morphometry of reindeer, Rangifer tarandus, and muskoxen, Ovibos moschatus.

Reindeer have been classified as intermediate feeders and muskoxen as grazers based on differences in digestive morphology and consumption of fibrous plants. We hypothesized that the digestive morphology of young (< 2 months) reindeer and muskoxen anticipates transitions in diet and determines the feeding strategy of each species at adulthood. We compared structural morphology and rates of cell division in the rumen, abomasum, duodenum and liver of reindeer and muskoxen as neonates (1 day old), during the transition from milk to forage (30-60 days old) and in adults (> 7 yr). Development in utero provided the neonate with a functioning mucosa of the gastric abomasum and duodenal mucosa with high surface enlargement for digestion and absorption of concentrated milks. Transition to forage was preceded by changes in ruminal papillae structure that increased surface area and likely contributed to active fermentation by 60 days of age. The abomasum also increased in acid-secreting parietal cells during the transition to forage, which may enhance digestion of plant and microbial proteins. Rates of cell division also indicated a sustained differentiation of tissue structure during the transitional period. Young arctic ruminants expressed digestive structures that preceded full function, which indicated the ultimate feeding strategy of each species. For example, the rumen of young muskoxen had thick cornified epithelia and muscle layers that would provide ruminal mucosa with better protection from fibrous abrasion and enhance motility of bulky diets. Conversely, young reindeer had more complex papillary shapes in the rumen and more foliate villi in the duodenum, indicating a greater absorptive capacity of these structures than in muskoxen. Ontogenetic programs, therefore, play the primary role for digestive development of reindeer and muskoxen and determine the nutritional strategies of adults.

Failure of detection of pneumothorax on initial chest radiograph.

Failure to detect a pneumothorax may have serious complications. A case of a pneumothorax, which may have been overlooked if thoracic computed tomography had not been performed, is discussed.

Mitochondrial phylogeography of moose (Alces alces): late pleistocene divergence and population expansion.

We examined phylogeographic relationships of moose (Alces alces) worldwide to test the proposed existence of two geographic races and to infer the timing and extent of demographic processes underpinning the expansion of this species across the Northern Hemisphere in the late Pleistocene. Sequence variation within the left hypervariable domain of the control region occurred at low or moderate levels worldwide and was structured geographically. Partitioning of genetic variance among regions indicated that isolation by distance was the primary agent for differentiation of moose populations but does not support the existence of distinct eastern and western races. Levels of genetic variation and structure of phylogenetic trees identify Asia as the origin of all extant mitochondrial lineages. A recent coalescence is indicated, with the most recent common ancestor dating to the last ice age. Moose have undergone two episodes of population expansion, likely corresponding to the final interstade of the most recent ice age and the onset of the current interglacial. Timing of expansion for the population in the Yakutia--Manchuria region of eastern Asia indicates that it is one of the oldest populations of moose and may represent the source of founders of extant populations in North America, which were colonized within the last 15,000 years. Our data suggest an extended period of low population size or a severe bottleneck prior to the divergence and expansion of extant lineages and a recent, less-severe bottleneck among European lineages. Climate change during the last ice age, acting through contraction and expansion of moose habitat and the flooding of the Bering land bridge, undoubtedly was a key factor influencing the divergence and expansion of moose populations.