Fluid dynamics alters liquid-liquid phase separation in confined aqueous two-phase systems.

Liquid-liquid phase separation is key to understanding aqueous two-phase systems (ATPS) arising throughout cell biology, medical science, and the pharmaceutical industry. Controlling the detailed morphology of phase-separating compound droplets leads to new technologies for efficient single-cell analysis, targeted drug delivery, and effective cell scaffolds for wound healing. We present a computational model of liquid-liquid phase separation relevant to recent laboratory experiments with gelatin-polyethylene glycol mixtures. We include buoyancy and surface-tension-driven finite viscosity fluid dynamics with thermally induced phase separation. We show that the fluid dynamics greatly alters the evolution and equilibria of the phase separation problem. Notably, buoyancy plays a critical role in driving the ATPS to energy-minimizing crescent-shaped morphologies, and shear flows can generate a tenfold speedup in particle formation. Neglecting fluid dynamics produces incorrect minimum-energy droplet shapes. The model allows for optimization of current manufacturing procedures for structured microparticles and improves understanding of ATPS evolution in confined and flowing settings important in biology and biotechnology.

Discovery of a functional, contracted heme-binding motif within a multiheme cytochrome.

Anaerobic ammonium-oxidizing (anammox) bacteria convert nitrite and ammonium via nitric oxide (NO) and hydrazine into dinitrogen gas by using a diverse array of proteins, including numerous c-type cytochromes. Many new catalytic and spectroscopic properties of c-type cytochromes have been unraveled by studies on the biochemical pathways underlying the anammox process. The unique anammox intermediate hydrazine is produced by a multiheme cytochrome c protein, hydrazine synthase, through the comproportionation of ammonium and NO and the input of three electrons. It is unclear how these electrons are delivered to hydrazine synthase. Here, we report the discovery of a functional tetraheme c-type cytochrome from the anammox bacterium Kuenenia stuttgartiensis with a naturally-occurring contracted Cys-Lys-Cys-His (CKCH) heme-binding motif, which is encoded in the hydrazine synthase gene cluster. The purified tetraheme protein (named KsTH) exchanged electrons with hydrazine synthase. Complementary spectroscopic techniques revealed that this protein harbors four low-spin hexa-coordinated hemes with His/Lys (heme 1), His/Cys (heme 2), and two His/His ligations (hemes 3 and 4). A genomic database search revealed that c-type cytochromes with a contracted CXCH heme-binding motif are present throughout the bacterial and archaeal domains in the tree of life, suggesting that this heme recognition site may be employed by many different groups of microorganisms.

The Water Hyacinth Microbiome: Link Between Carbon Turnover and Nutrient Cycling.

Water hyacinth (WH), a large floating plant, plays an important role in the biogeochemistry and ecology of many freshwaters globally. Its biogeochemical impact on wetland functioning is strongly mediated by the microbiome associated with its roots. However, little is known about the structure and function of this WH rhizobiome and its relation to wetland ecosystem functioning. Here, we unveil the core and transient rhizobiomes of WH and their key biogeochemical functions in two of the world's largest wetlands: the Amazon and the Pantanal. WH hosts a highly diverse microbial community shaped by spatiotemporal changes. Proteobacteria lineages were most common, followed by Actinobacteria and Planctomycetes. Deltaproteobacteria and Sphingobacteriia predominated in the core microbiome, potentially associated with polysaccharide degradation and fermentation of plant-derived carbon. Conversely, a plethora of lineages were transient, including highly abundant Acinetobacter, Acidobacteria subgroup 6, and methanotrophs, thus assuring diverse taxonomic signatures in the two different wetlands. Our findings point out that methanogenesis is a key driver of, and proxy for, community structure, especially during seasonal plant decline. We provide ecologically relevant insights into the WH microbiome, which is a key element linking plant-associated carbon turnover with other biogeochemical fluxes in tropical wetlands.

Effect of water management on microbial diversity and composition in an Italian rice field system.

Traditional rice cultivation consumes up to 2500 L of water per kg yield and new strategies such as the 'Alternate Wetting and Drying' (AWD) might be promising water-saving alternatives. However, they might have large impacts on the soil microbiology. In this study, we compared the bacterial and archaeal communities in experimental field plots, cultivated under continuously flooding (CF) and AWD management, by high-throughput sequencing of the 16S rRNA gene. We analysed alpha and beta diversity in bulk soil and on plant roots, in plots cultivated with two different rice cultivars. The strongest difference was found between soil and root communities. Beside others, the anaerobic methanotroph Methanoperedens was abundant in soil, however, we detected a considerable number of ANME-2a-2b on plant roots. Furthermore, root communities were significantly affected by the water management: Differential abundance analysis revealed the enrichment of aerobic and potentially plant-growth-promoting bacteria under AWD treatment, such as Sphingomonadaceae and Rhizobiaceae (both Alphaproteobacteria), and Bacteroidetes families. Microorganisms with an overall anaerobic lifestyle, such as various Delta- and Epsilonproteobacteria, and Firmicutes were depleted. Our study indicates that the bulk soil communities seem overall well adapted and more resistant to changes in the water treatment, whereas the root microbiota seems more vulnerable.

Improved phase-field models of melting and dissolution in multi-component flows.

We develop and analyse the first second-order phase-field model to combine melting and dissolution in multi-component flows. This provides a simple and accurate way to simulate challenging phase-change problems in existing codes. Phase-field models simplify computation by describing separate regions using a smoothed phase field. The phase field eliminates the need for complicated discretizations that track the moving phase boundary. However, standard phase-field models are only first-order accurate. They often incur an error proportional to the thickness of the diffuse interface. We eliminate this dominant error by developing a general framework for asymptotic analysis of diffuse-interface methods in arbitrary geometries. With this framework, we can consistently unify previous second-order phase-field models of melting and dissolution and the volume-penalty method for fluid-solid interaction. We finally validate second-order convergence of our model in two comprehensive benchmark problems using the open-source spectral code Dedalus.

Metabolic Overlap in Environmentally Diverse Microbial Communities.

The majority of microbial communities consist of hundreds to thousands of species, creating a massive network of organisms competing for available resources within an ecosystem. In natural microbial communities, it appears that many microbial species have highly redundant metabolisms and seemingly are capable of utilizing the same substrates. This is paradoxical, as theory indicates that species requiring a common resource should outcompete one another. To better understand why microbial species can coexist, we developed metabolic overlap (MO) as a new metric to survey the functional redundancy of microbial communities at the genome scale across a wide variety of ecosystems. Using metagenome-assembled genomes, we surveyed nearly 1,000 studies across nine ecosystem types. We found the highest MO in extreme (i.e., low pH/high temperature) and aquatic environments, while the lowest MO was observed in communities associated with animal hosts, the built/engineered environment, and soil. In addition, different metabolism subcategories were explored for their degree of MO. For instance, overlap in nitrogen metabolism was among the lowest in animal and engineered ecosystems, while species from the built environment had the highest overlap. Together, we present a metric that utilizes whole genome information to explore overlapping niches of microbes. This provides a detailed picture of potential metabolic competition and cooperation between species present in an ecosystem, indicates the main substrate types sustaining the community, and serves as a valuable tool to generate hypotheses for future research.

Orf-induced immunobullous disease: A distinct autoimmune blistering disorder.

BACKGROUND: Many complications have been reported after orf infection, including lymphadenopathy, secondary bacterial infection, and erythema multiforme. Rare associations with papulovesicular eruptions, including a bullous pemphigoid-like eruption, have also been described. OBJECTIVES: Our purpose was to clinically, histologically, and immunologically characterize two cases of orf-induced blistering disease, and to determine whether this condition represented a novel disease entity distinct from known immunobullous diseases. METHODS: Two patients were clinically described and skin biopsy specimens were collected for routine histology, direct immunofluorescence studies, and polymerase chain reaction analysis to detect orf viral DNA. Patients' sera were assessed for autoantibodies by indirect immunofluorescence studies using normal-appearing human salt-split skin, by Western blot analysis using keratinocyte extracts, dermal extracts, and recombinant type VII collagen, and immunoprecipitation studies of extracts from biosynthetically radiolabeled human keratinocytes. RESULTS: Two distinctive cases of severe, diffuse blistering eruptions after orf infection are described. In one patient, orf virus DNA was detected in the inciting orf lesion, but not in blistered skin, ruling out disseminated orf infection as a cause of the blisters. In both cases, histology revealed subepidermal blisters with mixed inflammatory cell infiltrates containing neutrophils and eosinophils, direct immunofluorescence microscopy studies demonstrated IgG and C3 deposited at the dermoepidermal junctions of perilesional skin, and indirect immunofluorescence studies demonstrated circulating antibasement membrane IgG that bound the dermal side of salt-split skin. Extensive immunoblot and immunoprecipitation studies failed to reveal a consistent, identifiable autoantigen. LIMITATIONS: We describe only two cases. The autoantigen recognized by circulating autoantibodies was not identified. CONCLUSIONS: Orf-induced immunobullous disease is a unique disease entity that is clinically and immunologically distinct from bullous pemphigoid, epidermolysis bullosa acquisita, and other known immunobullous conditions.

Linking Nitrogen Load to the Structure and Function of Wetland Soil and Rhizosphere Microbial Communities.

Wetland ecosystems are important reservoirs of biodiversity and significantly contribute to emissions of the greenhouse gases CO2, N2O, and CH4. High anthropogenic nitrogen (N) inputs from agriculture and fossil fuel combustion have been recognized as a severe threat to biodiversity and ecosystem functioning, such as control of greenhouse gas emissions. Therefore, it is important to understand how increased N input into pristine wetlands affects the composition and activity of microorganisms, especially in interaction with dominant wetland plants. In a series of incubations analyzed over 90 days, we disentangled the effects of N fertilization on the microbial community in bulk soil and the rhizosphere of Juncus acutiflorus, a common and abundant graminoid wetland plant. We observed an increase in greenhouse gas emissions when N is increased in incubations with J. acutiflorus, changing the system from a greenhouse gas sink to a source. Using 16S rRNA gene amplicon sequencing, we determined that the bacterial orders Opitutales, subgroup 6 Acidobacteria, and Sphingobacteriales significantly responded to high N availability. Based on metagenomic data, we hypothesize that these groups are contributing to the increased greenhouse gas emissions. These results indicated that increased N input leads to shifts in microbial activity within the rhizosphere, altering N cycling dynamics. Our study provides a framework for connecting environmental conditions of wetland bulk and rhizosphere soil to the structure and metabolic output of microbial communities. IMPORTANCE Microorganisms living within the rhizospheres of wetland plants significantly contribute to greenhouse gas emissions. Understanding how microbes produce these gases under conditions that have been imposed by human activities (i.e., nitrogen pollution) is important to the development of future management strategies. Our results illustrate that within the rhizosphere of the wetland plant Juncus acutiflorus, physiological differences associated with nitrogen availability can influence microbial activity linked to greenhouse gas production. By pairing taxonomic information and environmental conditions like nitrogen availability with functional outputs of a system such as greenhouse gas fluxes, we present a framework to link certain taxa to both nitrogen load and greenhouse gas production. We view this type of combined information as essential in moving forward in our understanding of complex systems such as rhizosphere microbial communities.

What dermatologists do not know about smallpox vaccination: results from a worldwide electronic survey.

The risk of a bioterrorist attack with smallpox has increased owing to breakthroughs in the de novo synthesis of long-chain DNA molecules. Although the leading roles of dermatologists in diagnosing recent outbreaks of cutaneous anthrax and monkeypox demonstrate the importance of dermatologist preparedness for bioterrorism, dermatologist knowledge regarding smallpox vaccination has not been extensively examined. We conducted a cross-sectional worldwide electronic survey of all members of the American Academy of Dermatology with available e-mail addresses. The response rate was 23% (1,303/5,723): 34% of respondents were women, 52% were age 50 or older, 85% practiced in the US, and 90% reported English as their primary language. Less than 37% indicated the Centers for Disease Control and Prevention estimated rate of death owing to smallpox vaccination (1 in 1,000,000), and many failed to identify vaccination contraindications: previous myocardial infarction (83%), angina (83%), congestive heart failure (78%), steroid eye drop use (65%), and the non-emergency vaccination of those younger than age 18 (95%). Widespread dermatologist smallpox vaccination knowledge deficits pinpoint opportunities for educational efforts.

Indoor tanning attitudes and practices of US dermatologists compared with other medical specialists.

OBJECTIVE: To compare the indoor tanning attitudes and practices of dermatologists with physicians in other medical specialties (internal medicine, pediatrics, and family medicine) commonly providing sun safety counseling to patients. DESIGN: Cross-sectional study. SETTING: Questionnaire mailed to randomly selected US dermatologists, internists, family practitioners, and pediatricians. RESULTS: The overall response rate was 38% (364/949): 71% indicated that patients had asked their opinions about indoor UV tanning, 80% believed that UV tanning was unsafe, and 90% agreed they would counsel patients against nonmedical indoor UV tanning. Many supported increased UV tanning legislation, including minimum age restrictions (91%) and parental consent requirements (90%). Dermatologists were significantly more likely than other physicians to respond to the survey (52% vs 31%, P<.001), speak with patients about indoor UV tanning (odds ratio [OR], 26.5; 95% confidence interval [CI], 9.5-74.1]), believe that indoor UV tanning is unsafe (OR, 14.0; 95% CI, 5.0-39.4), and support increased regulation (OR, 11.7; 95% CI, 1.5-88.5). Women discouraged indoor UV tanning more than men (OR, 5.2; 95% CI, 1.8-15.2). Physicians who had used indoor UV tanning (19%) more often agreed that non-UV tanning lotion (OR, 2.0; 95% CI, 1.1-3.8) and airbrush tanning (OR, 1.9; 95% CI, 1.1-3.4) were safe but did not differ in attitudes regarding UV tanning safety. Physicians practicing in the Northeast and Midwest were more likely to support UV tanning to improve mood (OR, 2.0; 95% CI, 1.1-3.5) and more commonly believed that UV tanning could help treat depression (OR, 2.6; 95% CI, 1.5-4.6) or prevent vitamin D deficiency (OR, 1.7; 95% CI, 1.0-2.8). CONCLUSIONS: Physicians, especially dermatologists, are frequently asked about and generally discourage indoor UV tanning. Dermatologists regard indoor UV tanning more negatively compared with other physicians. Physician sex and geographic location were associated with specific indoor UV tanning attitudes.

Dermatology Internet Yellow Page advertising.

BACKGROUND: Patients may use Internet Yellow Pages to help select a physician. OBJECTIVE: We sought to describe dermatology Internet Yellow Page advertising. METHODS: Dermatology advertisements in Colorado, California, New York, and Texas at 3 Yellow Page World Wide Web sites were systematically examined. RESULTS: Most advertisements (76%; 223/292) listed only one provider, 56 listed more than one provider, and 13 listed no practitioner names. Five advertisements listed provider names without any credentialing letters, 265 listed at least one doctor of medicine or osteopathy, and 9 listed only providers with other credentials (6 doctors of podiatric medicine and 3 registered nurses). Most advertisements (61%; 179/292) listed a doctor of medicine or osteopathy claiming board certification, 78% (139/179) in dermatology and 22% (40/179) in other medical specialties. Four (1%; 4/292) claims of board certification could not be verified (one each in dermatology, family practice, dermatologic/cosmetologic surgery, and laser surgery). Board certification could be verified for most doctors of medicine and osteopathy not advertising claims of board certification (68%; 41/60; 32 dermatology, 9 other specialties). A total of 50 advertisements (17%) contained unverifiable or no board certification information, and 47 (16%) listed a physician with verifiable board certification in a field other than dermatology. LIMITATIONS: All Internet Yellow Page World Wide Web sites and all US states were not examined. CONCLUSION: Nonphysicians, physicians board certified in medical specialties other than dermatology, and individuals without verifiable board certification in any medical specialty are advertising in dermatology Internet Yellow Pages. Many board-certified dermatologists are not advertising this certification.

Stable and sporadic symbiotic communities of coral and algal holobionts.

Coral and algal holobionts are assemblages of macroorganisms and microorganisms, including viruses, Bacteria, Archaea, protists and fungi. Despite a decade of research, it remains unclear whether these associations are spatial-temporally stable or species-specific. We hypothesized that conflicting interpretations of the data arise from high noise associated with sporadic microbial symbionts overwhelming signatures of stable holobiont members. To test this hypothesis, the bacterial communities associated with three coral species (Acropora rosaria, Acropora hyacinthus and Porites lutea) and two algal guilds (crustose coralline algae and turf algae) from 131 samples were analyzed using a novel statistical approach termed the Abundance-Ubiquity (AU) test. The AU test determines whether a given bacterial species would be present given additional sampling effort (that is, stable) versus those species that are sporadically associated with a sample. Using the AU test, we show that coral and algal holobionts have a high-diversity group of stable symbionts. Stable symbionts are not exclusive to one species of coral or algae. No single bacterial species was ubiquitously associated with one host, showing that there is not strict heredity of the microbiome. In addition to the stable symbionts, there was a low-diversity community of sporadic symbionts whose abundance varied widely across individual holobionts of the same species. Identification of these two symbiont communities supports the holobiont model and calls into question the hologenome theory of evolution.

Compliance with youth access regulations for indoor UV tanning.

OBJECTIVES: To describe youth access to indoor UV tanning and youth discount pricing incentives in 4 states with different age restrictions: Colorado (no age restrictions), Texas (age 13 years), Illinois (age 14 years), and Wisconsin (age 16 years). DESIGN: Cross-sectional telephone survey conducted in October 2003 using a standardized script to assess the practices of randomly selected UV tanning operators. PARTICIPANTS: Randomly selected licensed indoor UV tanning facility operators in Colorado, Texas, Illinois, and Wisconsin. MAIN OUTCOME MEASURES: Number of facilities (1) complying with indoor UV tanning minimum age regulations for a 12-year-old potential patron and a 15-year-old potential patron and (2) offering youth discounts. RESULTS: For a 12-year-old potential patron, 62% of facilities in states with minimum age restrictions prohibiting 12-year-olds had an operator report that they would not permit indoor tanning (Texas, 23%; Illinois, 74%; and Wisconsin, 89%) compared with 18% in Colorado, a state without youth access regulations. For a 15-year-old patron, most facilities in Wisconsin, the only state with a minimum age restriction for 15-year-olds, prohibited access (77%). Overall, 15% of operators offered youth discounts: Texas, 23%; Illinois, 14%; Wisconsin, 11%; and Colorado, 11%. CONCLUSIONS: Tanning facilities in 4 states offered price incentives directed at youths. State youth access regulations were associated with decreased youth access to indoor tanning. High compliance levels in states with long-standing youth access regulations (Illinois and Wisconsin) demonstrate the potential for successful tanning industry youth access regulation.

Metagenomic and satellite analyses of red snow in the Russian Arctic.

Cryophilic algae thrive in liquid water within snow and ice in alpine and polar regions worldwide. Blooms of these algae lower albedo (reflection of sunlight), thereby altering melting patterns (Kohshima, Seko & Yoshimura, 1993; Lutz et al., 2014; Thomas & Duval, 1995). Here metagenomic DNA analysis and satellite imaging were used to investigate red snow in Franz Josef Land in the Russian Arctic. Franz Josef Land red snow metagenomes confirmed that the communities are composed of the autotroph Chlamydomonas nivalis that is supporting a complex viral and heterotrophic bacterial community. Comparisons with white snow communities from other sites suggest that white snow and ice are initially colonized by fungal-dominated communities and then succeeded by the more complex C. nivalis-heterotroph red snow. Satellite image analysis showed that red snow covers up to 80% of the surface of snow and ice fields in Franz Josef Land and globally. Together these results show that C. nivalis supports a local food web that is on the rise as temperatures warm, with potential widespread impacts on alpine and polar environments worldwide.

Assessing evidence-based dermatology and evidence-based internal medicine curricula in US residency training programs: a national survey.

OBJECTIVES: To examine attitudes toward evidence-based medicine and evidence-based dermatology and to assess evidence-based training in US internal medicine and dermatology residency programs. METHODS: A 1-page self-administered questionnaire was mailed to residency training directors and chief residents at 104 dermatology and 103 internal medicine residency programs from the same or affiliated medical centers. RESULTS: Questionnaires were returned by respondents from 70 (68%) of 103 internal medicine programs and 86 (83%) of 104 dermatology programs. Most respondents (91% internal medicine and 70% dermatology) strongly agreed or agreed that evidence-based internal medicine/dermatology is valuable and should be included in residency training (93% internal medicine and 70% dermatology). Respondents from internal medicine programs agreed more strongly with both statements than respondents from dermatology programs (P =.001). Dedicated evidence-based curricula were in place at significantly more internal medicine programs (50 [71%] of 70) than dermatology programs (20 [23%] of 86) (P<.001). Curricula at internal medicine programs offered significantly more evidence-based medicine training sessions (24 vs 6; P<.001) and biostatistics sessions (10 vs 2.3; P =.03), and internal medicine programs more frequently evaluated the curricula using clinical question applications (56% vs 30%; P =.04). CONCLUSION: Despite favorable attitudes toward evidence-based dermatology, compared with internal medicine programs, dedicated evidence-based training is underdeveloped in dermatology programs.

Is high mole count a marker of more than melanoma risk? Eczema diagnosis is associated with melanocytic nevi in children.

BACKGROUND: The number of melanocytic nevi is the best single marker of increased melanoma risk. In a previous study, adults with severe eczema were reported to have significantly fewer nevi than adults without eczema. OBSERVATIONS: In a nested case-control design within a randomized, controlled interventional trial of additional sun protection vs standard care in 269 children, a history of eczema was reported by the parents of 44 (16%) of the children. More nevi were found in children with a parental report of previous eczema diagnosis than in children without reported eczema (median, 7.5 nevi vs 5.0 nevi; P =.01). Eczema diagnosis was most significantly associated with more melanocytic nevi in children with lightly pigmented skin (8.5 nevi vs 6.0 nevi; P <.001). In multivariate logistical regression analysis, including assessment of hair color, sun protection practices, and study assignment (intervention vs standard care), eczema status remained significantly predictive of nevi number in children (P <.001). CONCLUSIONS: In contrast to a previous study that associated severe eczema with fewer nevi in adults, in the present study children with a reported history of eczema had more nevi than children without a reported history of eczema.

Youth access laws: in the dark at the tanning parlor?

OBJECTIVE: To compare laws governing youth access to UV irradiation at indoor tanning facilities with laws governing youth access to tobacco. DESIGN: Tobacco and UV irradiation youth access laws were assessed via correspondence with public health offices and computerized legal searches of 6 industrialized nations with widely differing skin cancer incidence rates. SETTING: National, provincial, and state legal systems in Australia, Canada, France, New Zealand, the United Kingdom, and the United States. PARTICIPANTS: Public health, legal, information science, and medical professionals and government and tanning industry representatives. MAIN OUTCOME MEASURES: Statutes specifying age restrictions for the purchase of indoor tanning services or tobacco products. RESULTS: The 5 English-speaking countries with common law-based legal systems unilaterally prohibit youth access to tobacco but rarely limit youth access to UV irradiation from tanning salons. Only very limited regions in the United States and Canada prohibit youth access to indoor tanning facilities: Texas, Illinois, Wisconsin, and New Brunswick prohibit tanning salon use by minors younger than 13, 14, 16, and 18 years, respectively. In contrast, French law allows minors to purchase tobacco but prohibits those younger than 18 years from patronizing tanning salons. CONCLUSIONS: Youth access laws governing indoor tanning display remarkable variety. Uniform indoor tanning youth access laws modeled on the example of tobacco youth access laws merit consideration.

Indoor UV tanning operator opinion regarding youth access: an electronic survey.

BACKGROUND: Adolescents frequently use indoor tanning facilities, but little is known about tanning facility operator opinions regarding this use. Objective To assess indoor tanning operator attitudes and stated practices regarding youth access. METHODS: We electronically surveyed 89 indoor tanning facilities and 130 spas with active e-mail addresses. RESULTS: The survey response rate was 21% for both indoor tanning facilities (19/89) and spas (27/130). Most tanning operators (92%) felt that a client can be too young to receive indoor tanning, and most felt that written parental permission should be required (80%). Most facilities required adult accompaniment (92%), and most operators had discouraged a customer from receiving indoor tanning based on age (77%). The reported age of the youngest patron receiving indoor tanning ranged from 5 to 21 years. CONCLUSION: Our sample of indoor tanning facility operators believed that minimum age and parental consent regulations for indoor tanning should be required.