Acrogenospora terricola sp. nov., a fungal species associated with seeds of pioneer trees in the soil seed bank of a lowland forest in Panama.

As currently circumscribed, Acrogenospora (Acrogenosporaceae, Minutisphaerales, Dothideomycetes) is a genus of saprobic hyphomycetes with distinctive conidia. Although considered common and cosmopolitan, the genus is poorly represented by sequence data, and no neotropical representatives are present in public sequence databases. Consequently, Acrogenospora has been largely invisible to ecological studies that rely on sequence-based identification. As part of an effort to identify fungi collected during ecological studies, we identified strains of Acrogenospora isolated in culture from seeds in the soil seed bank of a lowland tropical forest in Panama. Here we describe Acrogenospora terricola sp. nov. based on morphological and phylogenetic analyses. We confirm that the genus has a pantropical distribution. The observation of Acrogenospora infecting seeds in a terrestrial environment contrasts with previously described species in the genus, most of which occur on decaying wood in freshwater environments. This work highlights the often hidden taxonomic value of collections derived from ecological studies of fungal communities and the ways in which rich sequence databases can shed light on the identity, distributions and diversity of cryptic microfungi.

Clinical outcomes of the biologically oriented preparation technique (BOPT) in fixed dental prostheses: A systematic review.

STATEMENT OF PROBLEM: The biologically oriented preparation technique is a concept with a vertical tooth preparation, gingitage, an immediate interim restoration preserving the clot, and a specific laboratory technique aiming to adapt the marginal periodontal tissue to a remodeled emergence profile of the crown. However, the published scientific evidence on this subject is limited. PURPOSE: The purpose of this systematic review was to analyze whether using the biologically oriented preparation technique leads to improved clinical outcomes in terms of probing depth, gingival inflammation index, gingival marginal stability, and fewer mechanical and biological complications. MATERIAL AND METHODS: Recommendations from the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines were used in this systematic review. An electronic search of the MEDLINE/PubMed, EMBASE, Science Direct, Wiley Online Library, Cochrane, and ProQuest databases was made for articles published between March 2010 and July 2021 using keywords. Three reviewers selected and analyzed all articles that mentioned the biologically oriented preparation technique and met the inclusion criteria. RESULTS: A total of 6 articles met the inclusion criteria: 1 prospective randomized clinical study, 1 randomized clinical study, 1 prospective clinical study, and 3 case series. According to these studies, of all the teeth treated with the biologically oriented preparation technique, probing depth (greater than 3 mm) increased in only 2.3%, gingival inflammation was present in 22.8%, gingival recession occurred in 1.7% (decreased gingival stability), and mechanical and biological failures occurred in 4.4% of the teeth. CONCLUSIONS: Fixed dental prosthesis treatments performed following the concept of the biologically oriented preparation technique did not increase probing depth and showed a moderate rate of gingival inflammation, lower recession rates, and lower mechanical and biological failures at the 5-year follow-up. The biologically oriented preparation technique appears to be a viable alternative technique for obtaining satisfactory and stable clinical results up to 5 years. Long-term randomized clinical trials are recommended to reach more conclusions about this protocol.

Defend, disrupt, and build: Guerrilla urbanist interventions and fighting gentrification in the barrio.

This study proposes guerrilla urbanist interventions (GUIs) as a domain to analyze some seemingly more conflictual and confrontational anti-gentrification efforts in the barrio. The historic and theoretical foundation of guerrillas informs the spatial and political conceptualization of these more confrontational urban interventions. The research examines anti-gentrification efforts in Boyle Heights and Santa Ana, California through this guerrilla urbanist intervention framework and analyses data collected through interviews and participant observation, and archival data comprised of public videos, writings, and manifestos. The analysis surfaces themes of "Defense," "Disruption," and "Building" to explain GUI's mode of establishing a new sociopolitical terrain in the neighborhood. GUIs use disruptions to delegitimize processes of community engagement in planning and development and create political spaces to voice complaints against displacement through criminalization, deportation, and gentrification. GUIs also ignite their own public process to try and remove certain actors from the neighborhood. Although GUIs are small and temporary, they help surface the complex political and economic structures that gentrification easily masks through art, culture, and community-based organizations. Political and economic interests become visible enough for individuals to at least reevaluate longstanding alliances and call to question the specific interests of certain actors and processes.

Dormancy-defense syndromes and tradeoffs between physical and chemical defenses in seeds of pioneer species.

Seeds of tropical pioneer trees have chemical and physical characteristics that determine their capacity to persist in the soil seed bank. These traits allow seeds to survive in the soil despite diverse predators and pathogens, and to germinate and recruit even decades after dispersal. Defenses in seedlings and adult plants often are described in terms of tradeoffs between chemical and physical defense, but the interplay of defensive strategies has been evaluated only rarely for seeds. Here we evaluated whether classes of seed defenses were negatively correlated across species (consistent with tradeoffs in defense strategies), or whether groups of traits formed associations across species (consistent with seed defense syndromes). Using 16 of the most common pioneer tree species in a neotropical lowland forest in Panama we investigated relationships among four physical traits (seed fracture resistance, seed coat thickness, seed permeability, and seed mass) and two chemical traits (number of phenolic compounds and phenolic peak area), and their association with seed persistence. In addition, seed toxicity was assessed with bioassays in which we evaluated the activity of seed extracts against representative fungal pathogens and a model invertebrate. We did not find univariate tradeoffs between chemical and physical defenses. Instead, we found that seed permeability - a trait that distinguishes physical dormancy from other dormancy types - was positively associated with chemical defense traits and negatively associated with physical defense traits. Using a linear discriminant analysis and a hierarchical cluster analysis we found evidence to distinguish three distinct seed defense syndromes that correspond directly with seed dormancy classes (i.e., quiescent, physical, and physiological). Our data suggest that short and long-term persistence of seeds can be achieved via two strategies: having permeable seeds that are well defended chemically, corresponding to the physiologically dormant defense syndrome; or having impermeable seeds that are well defended physically, corresponding to the physically dormant defense syndrome. In turn, transient seeds appear to have a lower degree of chemical and physical defenses, corresponding to the quiescent defense syndrome. Overall, we find that seed defense and seed dormancy are linked, suggesting that environmental pressures on seed persistence and for delayed germination can select for trait combinations defining distinct dormancy-defense syndromes.

Soilborne fungi have host affinity and host-specific effects on seed germination and survival in a lowland tropical forest.

The Janzen-Connell (JC) hypothesis provides a conceptual framework for explaining the maintenance of tree diversity in tropical forests. Its central tenet-that recruits experience high mortality near conspecifics and at high densities-assumes a degree of host specialization in interactions between plants and natural enemies. Studies confirming JC effects have focused primarily on spatial distributions of seedlings and saplings, leaving major knowledge gaps regarding the fate of seeds in soil and the specificity of the soilborne fungi that are their most important antagonists. Here we use a common garden experiment in a lowland tropical forest in Panama to show that communities of seed-infecting fungi are structured predominantly by plant species, with only minor influences of factors such as local soil type, forest characteristics, or time in soil (1-12 months). Inoculation experiments confirmed that fungi affected seed viability and germination in a host-specific manner and that effects on seed viability preceded seedling emergence. Seeds are critical components of reproduction for tropical trees, and the factors influencing their persistence, survival, and germination shape the populations of seedlings and saplings on which current perspectives regarding forest dynamics are based. Together these findings bring seed dynamics to light in the context of the JC hypothesis, implicating them directly in the processes that have emerged as critical for diversity maintenance in species-rich tropical forests.

Seedling growth responses to phosphorus reflect adult distribution patterns of tropical trees.

Soils influence tropical forest composition at regional scales. In Panama, data on tree communities and underlying soils indicate that species frequently show distributional associations to soil phosphorus. To understand how these associations arise, we combined a pot experiment to measure seedling responses of 15 pioneer species to phosphorus addition with an analysis of the phylogenetic structure of phosphorus associations of the entire tree community. Growth responses of pioneers to phosphorus addition revealed a clear tradeoff: species from high-phosphorus sites grew fastest in the phosphorus-addition treatment, while species from low-phosphorus sites grew fastest in the low-phosphorus treatment. Traits associated with growth performance remain unclear: biomass allocation, phosphatase activity and phosphorus-use efficiency did not correlate with phosphorus associations; however, phosphatase activity was most strongly down-regulated in response to phosphorus addition in species from high-phosphorus sites. Phylogenetic analysis indicated that pioneers occur more frequently in clades where phosphorus associations are overdispersed as compared with the overall tree community, suggesting that selection on phosphorus acquisition and use may be strongest for pioneer species with high phosphorus demand. Our results show that phosphorus-dependent growth rates provide an additional explanation for the regional distribution of tree species in Panama, and possibly elsewhere.

Do soil microbes and abrasion by soil particles influence persistence and loss of physical dormancy in seeds of tropical pioneers?

Germination from the soil seed bank (SSB) is an important determinant of species composition in tropical forest gaps, with seed persistence in the SSB allowing trees to recruit even decades after dispersal. The capacity to form a persistent SSB is often associated with physical dormancy, where seed coats are impermeable at the time of dispersal. Germination literature often speculates, without empirical evidence, that dormancy-break in physically dormant seeds is the result of microbial action and/or abrasion by soil particles. We tested the microbial/soil abrasion hypothesis in four widely distributed neotropical pioneer tree species (Apeiba membranacea, Luehea seemannii, Ochroma pyramidale, and Cochlospermum vitifolium). Seeds were buried in five common gardens in a lowland tropical forest in Panama, and recovered at 1, 3, 6, and 12 months after burial. Seed permeability, microbial infection, seed coat thickness, and germination were measured. Parallel experiments compared the germination fraction of fresh and aged seeds without soil contact, and in seeds as a function of seed permeability. Contrary to the microbial/soil abrasion hypothesis the proportion of permeable seeds, and of seeds infected by cultivable microbes, decreased as a function of burial duration. Furthermore, seeds stored in dark and dry conditions for 2 years showed a higher proportion of seed germination than fresh seeds in identical germination conditions. We determined that permeable seeds of A. membranacea and O. pyramidale had cracks in the chalazal area or lacked the chalazal plug, whereas all surfaces of impermeable seeds were intact. Our results are inconsistent with the microbial/soil abrasion hypothesis of dormancy loss and instead suggest the existence of multiple dormancy phenotypes, where a fraction of each seed cohort is dispersed in a permeable state and germinates immediately, while the impermeable seed fraction accounts for the persistent SSB. Thus, we conclude that fluctuations in the soil temperature in the absence of soil abrasion and microbial infection are sufficient to break physical dormancy on seeds of tropical pioneer trees.

Modelos explicativos de la dependencia y consumo de tabaco en estudiantes de preparatoria / An Explanatory Model of Tobacco Consumption among High School Students

El propósito principal del estudio fue explicar la dependencia tabáquica y el consumo de cigarros desde una perspectiva motivacional en una muestra de estudiantes de preparatoria de sexo indistinto. Se emplearon cuatro escalas del Inventario de Wisconsin de Motivos de Dependencia del Tabaco, una escala de normas paternas y una de amigos fumadores; así como dos medidas internacionales de consumo de cigarrillos y un cuestionario de dependencia tabáquica. El análisis de regresión múltiple de dependencia tabáquica mostró que exposición a claves, normas paternas y reforzamiento positivo explicaron el 54.30% de la varianza. Se elaboró un modelo estructural de la dependencia al tabaco que incluyó los motivos mencionados y el número de días de consumo, el cual se ajustó bien a los datos. Todos los efectos directos sobre las medidas de dependencia fueron significativos, así como las covarianzas entre los motivos. De acuerdo al estadístico Wald que se obtuvo en el análisis de clases latentes, hubo diferencias significativas entre los tres grupos en los cuatro indicadores: dependencia, exposición a claves, amigos fumadores y número de días de consumo.

The main purpose of the study was to explain tobacco dependence and consumption of cigarettes from a motivational perspective on a sample of high school students of both sexes. We used four scales of the Wisconsin Inventory of Smoking Dependence Motives, a scale of parental rules and a scale of smoking friends; as well as two international measures for cigarette consumption and a tobacco dependence questionnaire. The multiple regression analysis of tobacco dependence showed that the key exposure, parental rules and positive reinforcement, accounted for 54.30% of the variance. In this study, was developed a structural model of the tobacco dependence that included the four motives and the number of days of consumption, which fits well with the data; all direct effects on measures of dependency were significant, as the covariance among the motives. According to the Wald statistic obtained in the latent class analysis, there were significant differences among the three groups in the four indicators: dependency, exposure to key, smoking friends and number of days of consumption.

Surviving chytridiomycosis: differential anti-Batrachochytrium dendrobatidis activity in bacterial isolates from three lowland species of Atelopus.

In the Neotropics, almost every species of the stream-dwelling harlequin toads (genus Atelopus) have experienced catastrophic declines. The persistence of lowland species of Atelopus could be explained by the lower growth rate of Batrachochytrium dendrobatidis (Bd) at temperatures above 25 °C. We tested the complementary hypothesis that the toads' skin bacterial microbiota acts as a protective barrier against the pathogen, perhaps delaying or impeding the symptomatic phase of chytridiomycosis. We isolated 148 cultivable bacterial strains from three lowland Atelopus species and quantified the anti-Bd activity through antagonism assays. Twenty-six percent (38 strains representing 12 species) of the bacteria inhibited Bd growth and just two of them were shared among the toad species sampled in different localities. Interestingly, the strongest anti-Bd activity was measured in bacteria isolated from A. elegans, the only species that tested positive for the pathogen. The cutaneous bacterial microbiota is thus likely a fitness-enhancing trait that may (adaptation) or not (exaptation) have appeared because of natural selection mediated by chytridiomycosis. Our findings reveal bacterial strains for development of local probiotic treatments against chytridiomycosis and also shed light on the mechanisms behind the frog-bacteria-pathogen interaction.

The genus Cecropia: a biological clock to estimate the age of recently disturbed areas in the Neotropics.

Forest successional processes following disturbance take decades to play out, even in tropical forests. Nonetheless, records of vegetation change in this ecosystem are scarce, increasing the importance of the chronosequence approach to study forest recovery. However, this approach requires accurate dating of secondary forests, which until now was a difficult and/or expensive task. Cecropia is a widespread and abundant pioneer tree genus of the Neotropics. Here we propose and validate a rapid and straightforward method to estimate the age of secondary forest patches based on morphological observations of Cecropia trees. We found that Cecropia-inferred ages were highly correlated with known ages of the forest. We also demonstrate that Cecropia can be used to accurately date disturbances and propose twenty-one species distributed all over the geographical range of the genus as potential secondary forest chronometer species. Our method is limited in applicability by the maximal longevity of Cecropia individuals. Although the oldest chronosequence used in this study was 20 years old, we argue that at least for the first four decades after disturbance, the method described in this study provides very accurate estimations of secondary forest ages. The age of pioneer trees provides not only information needed to calculate the recovery of carbon stocks that would help to improve forest management, but also provides information needed to characterize the initial floristic composition and the rates of species remigration into secondary forest. Our contribution shows how successional studies can be reliably and inexpensively extended without the need to obtain forest ages based on expensive or potentially inaccurate data across the Neotropics.

Bd on the beach: high prevalence of Batrachochytrium dendrobatidis in the lowland forests of Gorgona Island (Colombia, South America).

The amphibian chytrid fungus, Batrachochytrium dendrobatidis, Bd, has been implicated in the decimation and extinction of many amphibian populations worldwide, especially at mid and high elevations. Recent studies have demonstrated the presence of the pathogen in the lowlands from Australia and Central America. We extend here its elevational range by demonstrating its presence at the sea level, in the lowland forests of Gorgona Island, off the Pacific coast of Colombia. We conducted two field surveys, separated by four years, and diagnosed Bd by performing polymerase chain reactions on swab samples from the skin of five amphibian species. All species, including the Critically Endangered Atelopus elegans, tested positive for the pathogen, with prevalences between 3.9 % in A. elegans (in 2010) and 52 % in Pristimantis achatinus. Clinical signs of chytridiomycosis were not detected in any species. To our knowledge, this is the first report of B. dendrobatidis in tropical lowlands at sea level, where temperatures may exceed optimal growth temperatures of this pathogen. This finding highlights the need to understand the mechanisms allowing the interaction between frogs and pathogen in lowland ecosystems.

Three new genera representing novel lineages of Sordariomycetidae (Sordariomycetes, Ascomycota) from tropical freshwater habitats in Costa Rica.

Three new genera are established in the Sordariomycetidae based on morphological and molecular data (SSU and LSU nrDNA) to accommodate five ascomycete species collected from submerged woody debris in freshwater habitats from Costa Rica. The genus Bullimyces contains three new species, B. communis, B. costaricensis and B. aurisporus. Bullimyces is characterized by globose to subglobose, membranous, black, ostiolate ascomata; deliquescent, hyaline, globose cells that fill the center of the centrum; unitunicate asci that deliquesce early in some species; and septate, thick-walled ascospores with or without gelatinous sheaths or appendages. Bullimyces species form a well supported clade with 100% bootstrap support, but the position of the genus in the Sordariomycetidae remains unclear. The second genus, Riomyces, is represented by a single species, R. rotundus. Riomyces is characterized by globose to subglobose, membranous, black, ostiolate ascomata, unitunicate, cylindrical asci, hyaline, globose cells that fill the hamathecium and septate, thick-walled ascospores with a gelatinous sheath. Although Riomyces is morphologically similar to Bullimyces, the two genera did not group together with support in any analysis. The third genus, Hydromelitis, is represented by a single species, H. pulchella. Hydromelitis is characterized by pyriform, membranous, black, ostiolate ascomata, unitunicate asci lacking an apical structure, simple, thin-walled, septate paraphyses and hyaline to golden yellow, multiseptate, thick-walled ascospores with a gelatinous sheath. Bullimyces, Riomyces and Hydromelitis were nested within an unsupported clade consisting of members of the Ophiostomatales, Magnaporthales and freshwater Annulatacaceae sensu lato and sensu stricto.

Within-individual variation of trunk and branch xylem density in tropical trees.

PREMISE OF THE STUDY: Wood density correlates with mechanical and physiological strategies of trees and is important for estimating global carbon stocks. Nonetheless, the relationship between branch and trunk xylem density has been poorly explored in neotropical trees. Here, we examine this relationship in trees from French Guiana and its variation among different families and sites, to improve the understanding of wood density in neotropical forests. METHODS: Trunk and branch xylem densities were measured for 1909 trees in seven sites across French Guiana. A major-axis fit was performed to explore their general allometric relationship and its variation among different families and sites. KEY RESULTS: Trunk xylem and branch xylem densities were significantly positively correlated, and their relationship explained 47% of the total variance. Trunk xylem was on average 9% denser than branch xylem. Family-level differences and interactions between family and site accounted for more than 40% of the total variance, whereas differences among sites explained little variation. CONCLUSIONS: Variation in xylem density within individual trees can be substantial, and the relationship between branch xylem and trunk xylem densities varies considerably among families and sites. As such, whole-tree biomass estimates based on nondestructive branch sampling should correct for both taxonomic and environmental factors. Furthermore, detailed estimates of the vertical distribution of wood density within individual trees are needed to determine the extent to which relying solely upon measures of trunk wood density may cause carbon stocks in tropical forests to be overestimated.

Continental-scale patterns of Cecropia reproductive phenology: evidence from herbarium specimens.

Plant phenology is concerned with the timing of recurring biological events. Though phenology has traditionally been studied using intensive surveys of a local flora, results from such surveys are difficult to generalize to broader spatial scales. In this study, contrastingly, we assembled a continental-scale dataset of herbarium specimens for the emblematic genus of Neotropical pioneer trees, Cecropia, and applied Fourier spectral and cospectral analyses to investigate the reproductive phenology of 35 species. We detected significant annual, sub-annual and continuous patterns, and discuss the variation in patterns within and among climatic regions. Although previous studies have suggested that pioneer species generally produce flowers continually throughout the year, we found that at least one third of Cecropia species are characterized by clear annual flowering behaviour. We further investigated the relationships between phenology and climate seasonality, showing strong associations between phenology and seasonal variations in precipitation and temperature. We also verified our results against field survey data gathered from the literature. Our findings indicate that herbarium material is a reliable resource for use in the investigation of large-scale patterns in plant phenology, offering a promising complement to local intensive field studies.

Autoria en cirugía de pancreatitis aguda necrohemorragica en altura (1987 a 1998) / Authorship in surgery of pancreatitis, acute necrotizing in altitude

La pancreatitis aguda es una entidad clínica en la que existe una inflamación de la glándula con la participación enzimática, liberación intersticial y digestión de la misma. La activación de la tripsina en el páncreas puede ser desastrosa; una vez que se ha iniciado la inflamación se liberan mediadores pro inflamatorios incluyendo IL1, 2, 6, 8, TNF-alfa y PAF. La progresión del edema a la necrosis pancreática puede deberse en parte a los modelos de TNF-alfa. Se asocia a causas identificables (cálculos y alcoholismo), aun cuando existe predisposición genética. La pancreatitis severa implica un riesgo de muerte, requiere un tratamiento agresivo desde el Servicio de Emergencia, Centro Quirúrgico y Cuidados Intensivos. Existen varios criterios para el pronóstico que incluyen a la edad, constantes sanguíneas, bioquímicas y de gases (criterios de Ranson y de Glasgow). La presente investigación en el Hospital Nacional del Sur Este - Essalud del Cusco, evalúa los casos de pancreatitis aguda necrohemorrágica en altura (3340 m.s.n.m.), con diagnóstico y tratamiento quirúrgico, en los últimos doce años. Se analizaron 34 historias, de un total de 75 pacientes tratados quirúrgicamente por la patología en estudio. Los resultados se analizaron con el paquete estadístico Epinfo, Microsoft Excel. La edad promedio de los pacientes fue de 49 años en un rango de 28 a 75 años. Se encontró una relación significativa entre el sexo del paciente y el alcoholismo crónico, siendo ésta mayor en varones que en mujeres. Los pacientes presentaron una media de 2 días de tiempo de enfermedad, siendo el promedio de estancia hospitalaria de 8 días. El diagnóstico pre operatorio fue de abdomen agudo quirúrgico, colecistitis aguda, pancreatitis, peritonitis. Los procedimientos quirúrgicos fueron laparatomía exploradora, colecistectomía, coledocotomía y drenaje de la vía biliar, drenaje del lecho pancreático, irrigación peritoneal contínua. La litiasis vesicular estuvo presente en el 70 por ciento de casos. Los resultados de los análisis de laboratorio dentro de las primeras 24 horas fueron los siguientes: Leucocitos 1500 mm3; Glucosa sérica 7.3 mmol/L; Urea sérica 16 mml/L; Calcio sérico 2 mmol/L; DHL sérico 350 U/L; TGO sérico 40 U/L; Amilasa sérica 433 U/L. dentro de las 48 horas de ingreso hematocrito disminuido en 7.46 por ciento; HCO3 18.18 mmol/L; PCO2 27.75 mmHg; PO2 64.8 mmHg; pH 7.42; Sat O2 91.58 por ciento; Sodio 144 mEq/L; Potasio 2.97 MeQ/L; Cloro 102.7 Meq/L...