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1.
Arch Sex Behav ; 53(6): 2091-2109, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38478164

RESUMEN

The mating effort questionnaire (MEQ) is a multi-dimensional self-report instrument that captures factors reflecting individual effort in upgrading from a current partner, investment in a current partner, and mate seeking when not romantically paired. In the current studies, we sought to revise the MEQ so that it distinguishes among two facets of mate seeking-mate locating and mate attracting-to enable a more nuanced measurement and understanding of individual mating effort. Moreover, we developed additional items to better measure partner investment. In total, the number of items was increased from 12 to 26. In Study 1, exploratory factor analysis revealed that a four-factor solution, reflecting partner upgrading, mate locating, mate attracting, and partner investment, yielded the best fit. In Study 2, this structure was replicated using confirmatory factor analysis in an independent sample. Based on extant studies documenting the relationships between psychopathy, short-term mating effort, and sexual risk taking, a structural equation model (SEM) indicated that trait psychopathy positively predicted mate locating, mate attracting, and partner upgrading and negatively predicted partner investment. A separate SEM showed that partner upgrading positively predicted risky sexual behaviors, while partner upgrading and mate locating positively predicted acceptance of cosmetic surgery.


Asunto(s)
Conducta Sexual , Parejas Sexuales , Humanos , Masculino , Encuestas y Cuestionarios , Parejas Sexuales/psicología , Conducta Sexual/psicología , Femenino , Adulto , Adulto Joven , Adolescente , Análisis Factorial , Reproducibilidad de los Resultados
2.
Community Ment Health J ; 59(8): 1479-1489, 2023 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-37162662

RESUMEN

Young adults with first episode psychosis use cannabis at high rates. In light of progressively tolerant attitudes toward cannabis, decreased perceptions of risk, and limited implementation of substance use modules within coordinated specialty care (CSC) programs, this study sought to describe factors contributing to CSC providers' intentions to implement motivational enhancement therapy (MET) for cannabis reduction. Two focus groups were conducted with CSC providers (n = 14), with questions guided by theory of planned behavior. Content and thematic analyses were conducted to identify salient themes associated with the theory. Participants generally indicated intentions to implement MET; limiting factors included concerns about clients' willingness to discuss cannabis use, perception of support for abstinence-only goals, and concerns about intervention mechanics such as computerized assessments. To reduce barriers limiting provider intention to implement MET, authors recommend training on assessment protocols, the merits of harm-reduction, and strategies for lower-risk cannabis use.Please confirm if the author names are presented accurately and in the correct sequence. Author 1 Given name: [Ryan] Last name [Petros]. Author 2 Given name: [Denise D.] Last name [Walker]. Author 3 Given name: [Adam] Last name [Davis]. Author 4 Given name: [Maria] Last name [Monroe-DeVita]. Also, kindly confirm the details in the metadata are correct.Confirmed!

3.
Int J Syst Evol Microbiol ; 72(10)2022 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-36314898

RESUMEN

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.


Asunto(s)
Ascomicetos , Banco de Semillas , Técnicas de Tipificación Bacteriana , Composición de Base , ADN Bacteriano/genética , Ácidos Grasos/química , Bosques , Filogenia , ARN Ribosómico 16S/genética , Semillas/microbiología , Análisis de Secuencia de ADN , Suelo , Clima Tropical , Panamá
4.
Arch Sex Behav ; 51(1): 3-37, 2022 01.
Artículo en Inglés | MEDLINE | ID: mdl-33025291

RESUMEN

Researchers have highlighted numerous sociocultural factors that have been shown to underpin human appearance enhancement practices, including the influence of peers, family, the media, and sexual objectification. Fewer scholars have approached appearance enhancement from an evolutionary perspective or considered how sociocultural factors interact with evolved psychology to produce appearance enhancement behavior. Following others, we argue that evidence from the field of evolutionary psychology can complement existing sociocultural models by yielding unique insight into the historical and cross-cultural ubiquity of competition over aspects of physical appearance to embody what is desired by potential mates. An evolutionary lens can help to make sense of reliable sex and individual differences that impact appearance enhancement, as well as the context-dependent nature of putative adaptations that function to increase physical attractiveness. In the current review, appearance enhancement is described as a self-promotion strategy used to enhance reproductive success by rendering oneself more attractive than rivals to mates, thereby increasing one's mate value. The varied ways in which humans enhance their appearance are described, as well as the divergent tactics used by women and men to augment their appearance, which correspond to the preferences of opposite-sex mates in a heterosexual context. Evolutionarily relevant individual differences and contextual factors that vary predictably with appearance enhancement behavior are also discussed. The complementarity of sociocultural and evolutionary perspectives is emphasized and recommended avenues for future interdisciplinary research are provided for scholars interested in studying appearance enhancement behavior.


Asunto(s)
Evolución Biológica , Apariencia Física , Femenino , Heterosexualidad/psicología , Humanos , Masculino , Conducta Sexual/psicología , Parejas Sexuales/psicología
5.
Plant Cell Physiol ; 62(11): 1770-1785, 2021 Dec 10.
Artículo en Inglés | MEDLINE | ID: mdl-34453831

RESUMEN

Herbicide resistance in weeds can be conferred by target-site and/or non-target-site mechanisms, such as rapid metabolic detoxification. Resistance to the very-long-chain fatty acid-inhibiting herbicide, S-metolachlor, in multiple herbicide-resistant populations (CHR and SIR) of waterhemp (Amaranthus tuberculatus) is conferred by rapid metabolism compared with sensitive populations. However, enzymatic pathways for S-metolachlor metabolism in waterhemp are unknown. Enzyme assays using S-metolachlor were developed to determine the specific activities of glutathione S-transferases (GSTs) and cytochrome P450 monooxygenases (P450s) from CHR and SIR seedlings to compare with tolerant corn and sensitive waterhemp (WUS). GST activities were greater (∼2-fold) in CHR and SIR compared to WUS but much less than corn. In contrast, P450s in microsomal extracts from CHR and SIR formed O-demethylated S-metolachlor, and their NADPH-dependent specific activities were greater (>20-fold) than corn or WUS. Metabolite profiles of S-metolachlor generated via untargeted and targeted liquid chromatography-mass spectrometry from CHR and SIR differed from WUS, with greater relative abundances of O-demethylated S-metolachlor and O-demethylated S-metolachlor-glutathione conjugates formed by CHR and SIR. In summary, our results demonstrate that S-metolachlor metabolism in resistant waterhemp involves Phase I and Phase II metabolic activities acting in concert, but the initial O-demethylation reaction confers resistance.


Asunto(s)
Acetamidas/farmacología , Amaranthus/metabolismo , Resistencia a los Herbicidas , Herbicidas/farmacología , Zea mays/metabolismo , Amaranthus/efectos de los fármacos , Redes y Vías Metabólicas , Malezas/efectos de los fármacos , Malezas/metabolismo , Zea mays/efectos de los fármacos
6.
Mod Pathol ; 34(5): 904-921, 2021 05.
Artículo en Inglés | MEDLINE | ID: mdl-33311649

RESUMEN

Massively parallel sequencing (MPS) has become a viable diagnostic tool to interrogate genetic profiles of numerous tumors but has yet to be routinely adopted in the setting of lymphoma. Here, we report the empirical application of a targeted 40-gene panel developed for use in mature lymphoid neoplasms (MLNs) and report our experience on over 500 cases submitted for MPS during the first year of its clinical use. MPS was applied to both fresh and fixed specimens. The most frequent diagnoses were diffuse large B-cell lymphoma (116), chronic lymphocytic leukemia/small lymphocytic lymphoma (60), marginal zone lymphoma (52), and follicular lymphoma (43), followed by a spectrum of mature T-cell neoplasms (40). Of 534 cases submitted, 471 generated reportable results in MLNs, with disease-associated variants (DAVs) detected in 241 cases (51.2%). The most frequent DAVs affected TP53 (30%), CREBBP (14%), MYD88 (14%), TNFRSF14 (10%), TNFAIP3 (10%), B2M (7%), and NOTCH2 (7%). The bulk of our findings confirm what is reported in the scientific literature. While a substantial majority of mutations did not directly impact diagnosis, MPS results were utilized to either change, refine, or facilitate the final diagnosis in ~10.8% of cases with DAVs and 5.5% of cases overall. In addition, we identified preanalytic variables that significantly affect assay performance highlighting items for specimen triage. We demonstrate the technical viability and utility of the judicious use of a targeted MPS panel that may help to establish general guidelines for specimen selection and diagnostic application in MLNs in routine clinical practice.


Asunto(s)
Biomarcadores de Tumor/genética , Leucemia Linfocítica Crónica de Células B/diagnóstico , Linfoma de Células B de la Zona Marginal/diagnóstico , Linfoma Folicular/diagnóstico , Linfoma de Células B Grandes Difuso/diagnóstico , Perfilación de la Expresión Génica , Secuenciación de Nucleótidos de Alto Rendimiento , Humanos , Leucemia Linfocítica Crónica de Células B/genética , Linfoma de Células B de la Zona Marginal/genética , Linfoma Folicular/genética , Linfoma de Células B Grandes Difuso/genética
7.
Development ; 144(8): 1477-1483, 2017 04 15.
Artículo en Inglés | MEDLINE | ID: mdl-28242610

RESUMEN

Left-right (LR) asymmetry is a fundamental feature of internal anatomy, yet the emergence of morphological asymmetry remains one of the least understood phases of organogenesis. Asymmetric rotation of the intestine is directed by forces outside the gut, but the morphogenetic events that generate anatomical asymmetry in other regions of the digestive tract remain unknown. Here, we show in mouse and Xenopus that the mechanisms that drive the curvature of the stomach are intrinsic to the gut tube itself. The left wall of the primitive stomach expands more than the right wall, as the left epithelium becomes more polarized and undergoes radial rearrangement. These asymmetries exist across several species, and are dependent on LR patterning genes, including Foxj1, Nodal and Pitx2 Our findings have implications for how LR patterning manifests distinct types of morphological asymmetries in different contexts.


Asunto(s)
Tipificación del Cuerpo , Estómago/anatomía & histología , Estómago/embriología , Animales , Endodermo/embriología , Endodermo/metabolismo , Epitelio/embriología , Epitelio/metabolismo , Proteínas de Homeodominio/metabolismo , Ratones , Rotación , Transducción de Señal , Factores de Transcripción/metabolismo , Xenopus/embriología , Proteína del Homeodomínio PITX2
9.
Am J Hematol ; 95(7): 799-808, 2020 07.
Artículo en Inglés | MEDLINE | ID: mdl-32249963

RESUMEN

This multi-institutional study retrospectively evaluated clinicopathologic and genetic characteristics in 351 patients with core-binding-factor acute myeloid leukemia (CBF-AML), comprising 69 therapy-related (t-CBF-AML) and 282 de novo cases. The T-CBF-AML patients were older, had lower WBC counts, and slightly higher hemoglobin than patients with de novo disease. Secondary cytogenetic abnormalities were more frequent in patients with de novo disease than t-CBF-AML (57.1% vs 41.1%, P = .026). Patients with secondary cytogenetic abnormalities had longer overall survival (OS) than those without abnormalities (median 190 vs 87 months, P = .021); trisomy 8, trisomy 22, and loss of the X or Y chromosome were associated with longer OS. In the 165 cases performed of targeted gene sequencing, pathogenic mutations were detected in 75.7% of cases, and were more frequent in de novo than in therapy-related disease (P = .013). Mutations were found in N/KRAS (37.0%), FLT3 (27.8%), KIT (17.2%), TET2 (4.9%), and ASXL1 (3.9%). The TET2 mutations were associated with shorter OS (P = .012) while N/KRAS mutation was associated with longer OS in t(8;21) AML patients (P = .001). The KIT mutation did not show prognostic significance in this cohort. Although they received similar therapy, t-CBF-AML patients had shorter OS than de novo patients (median 69 vs 190 months, P = .038). In multivariate analysis of all patients, older age and absence of any secondary cytogenetic abnormalities were significant predictors of shorter OS. Among the t-CBF-AML subset, age and hemoglobin were significant on multivariate analysis. This study demonstrated that although de novo and t-CBF-AML patients share many features, t-CBF-AML patients have worse clinical outcome than de novo patients.


Asunto(s)
Aberraciones Cromosómicas , Factores de Unión al Sitio Principal , Leucemia Mieloide Aguda , Proteínas de Neoplasias , Adulto , Factores de Unión al Sitio Principal/genética , Factores de Unión al Sitio Principal/metabolismo , Supervivencia sin Enfermedad , Femenino , Humanos , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/metabolismo , Leucemia Mieloide Aguda/mortalidad , Leucemia Mieloide Aguda/terapia , Masculino , Persona de Mediana Edad , Proteínas de Neoplasias/genética , Proteínas de Neoplasias/metabolismo , Estudios Retrospectivos , Tasa de Supervivencia
10.
Proc Natl Acad Sci U S A ; 114(43): 11458-11463, 2017 10 24.
Artículo en Inglés | MEDLINE | ID: mdl-28973927

RESUMEN

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.


Asunto(s)
Bosques , Hongos/aislamiento & purificación , Germinación/fisiología , Semillas/microbiología , Semillas/fisiología , Clima Tropical , Especificidad del Huésped , Plantas/clasificación , Plantas/microbiología , Microbiología del Suelo
11.
J Allergy Clin Immunol ; 144(3): 839-845.e10, 2019 09.
Artículo en Inglés | MEDLINE | ID: mdl-31247265

RESUMEN

BACKGROUND: Telomere length (TL) can serve as a potential biomarker for conditions associated with chronic oxidative stress and inflammation, such as asthma. Air pollution can induce oxidative stress. Understanding the relationship between TL, asthma, and air pollution is important for identifying risk factors contributing to unhealthy aging in children. OBJECTIVES: We sought to investigate associations between exposures to ambient air pollutants and TL in African American children and adolescents and to examine whether African ancestry, asthma status, and steroid medication use alter the association. METHODS: Linear regression was used to examine associations between absolute telomere length (aTL) and estimated annual average residential ozone (O3) and fine particulate matter with a diameter of 2.5 µm or less (PM2.5) exposures in a cross-sectional analysis of 1072 children in an existing asthma case-control study. African ancestry, asthma status, and use of steroid medications were examined as effect modifiers. RESULTS: Participants' aTLs were measured by using quantitative PCR. A 1-ppb and 1 µg/m3 increase in annual average exposure to O3 and PM2.5 were associated with a decrease in aTL of 37.1 kilo-base pair (kb; 95% CI, -66.7 to -7.4 kb) and 57.1 kb (95% CI, -118.1 to 3.9 kb), respectively. African ancestry and asthma were not effect modifiers; however, exposure to steroid medications modified the relationships between TL and pollutants. Past-year exposure to O3 and PM2.5 was associated with shorter TLs in patients without steroid use. CONCLUSION: Exposure to air pollution was associated with shorter TLs in nonasthmatic children and adolescents. This was not the case for asthmatic children as a group, but those receiving steroid medication had less shortening than those not using steroids. Reduced exposure to air pollution in childhood might help to preserve TL.


Asunto(s)
Contaminación del Aire , Asma/tratamiento farmacológico , Negro o Afroamericano , Exposición a Riesgos Ambientales , Esteroides/uso terapéutico , Telómero , Adolescente , Adulto , Contaminantes Atmosféricos , Asma/etnología , Niño , Humanos , Ozono , Material Particulado , Adulto Joven
12.
Pharmacogenomics J ; 19(3): 249-259, 2019 06.
Artículo en Inglés | MEDLINE | ID: mdl-30206298

RESUMEN

Short-acting ß2-adrenergic receptor agonists (SABAs) are the most commonly prescribed asthma medications worldwide. Response to SABAs is measured as bronchodilator drug response (BDR), which varies among racial/ethnic groups in the United States. However, the genetic variation that contributes to BDR is largely undefined in African Americans with asthma. To identify genetic variants that may contribute to differences in BDR in African Americans with asthma, we performed a genome-wide association study (GWAS) of BDR in 949 African-American children with asthma, genotyped with the Axiom World Array 4 (Affymetrix, Santa Clara, CA) followed by imputation using 1000 Genomes phase III genotypes. We used linear regression models adjusting for age, sex, body mass index (BMI) and genetic ancestry to test for an association between BDR and genotype at single-nucleotide polymorphisms (SNPs). To increase power and distinguish between shared vs. population-specific associations with BDR in children with asthma, we performed a meta-analysis across 949 African Americans and 1830 Latinos (total = 2779). Finally, we performed genome-wide admixture mapping to identify regions whereby local African or European ancestry is associated with BDR in African Americans. We identified a population-specific association with an intergenic SNP on chromosome 9q21 that was significantly associated with BDR (rs73650726, p = 7.69 × 10-9). A trans-ethnic meta-analysis across African Americans and Latinos identified three additional SNPs within the intron of PRKG1 that were significantly associated with BDR (rs7903366, rs7070958 and rs7081864, p ≤ 5 × 10-8). Our results failed to replicate in three additional populations of 416 Latinos and 1615 African Americans. Our findings indicate that both population-specific and shared genetic variation contributes to differences in BDR in minority children with asthma, and that the genetic underpinnings of BDR may differ between racial/ethnic groups.

13.
Radiographics ; 39(4): 1098-1107, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31125293

RESUMEN

Facial transplant (FT) is a viable option for patients with severe craniomaxillofacial deformities. Transplant imaging requires coordination between radiologists and surgeons and an understanding of the merits and limitations of imaging modalities. Digital subtraction angiography and CT angiography are critical to mapping vascular anatomy, while volume-rendered CT allows evaluation of osseous defects and landmarks used for surgical cutting guides. This article highlights the components of successful FT imaging at two institutions and in two index cases. A deliberate stepwise approach to performance and interpretation of preoperative FT imaging, which consists of the modalities and protocols described here, is essential to seamless integration of the multidisciplinary FT team. ©RSNA, 2019 See discussion on this article by Lincoln .


Asunto(s)
Angiografía de Substracción Digital/métodos , Angiografía por Tomografía Computarizada/métodos , Cara/diagnóstico por imagen , Trasplante Facial , Cuidados Preoperatorios/métodos , Adulto , Quemaduras/diagnóstico por imagen , Quemaduras/cirugía , Anomalías Craneofaciales/diagnóstico por imagen , Anomalías Craneofaciales/cirugía , Huesos Faciales/diagnóstico por imagen , Traumatismos Faciales/diagnóstico por imagen , Traumatismos Faciales/cirugía , Humanos , Imagenología Tridimensional , Masculino , Selección de Paciente , Flebografía/métodos , Adulto Joven
14.
Prehosp Emerg Care ; 23(3): 319-326, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-30257596

RESUMEN

OBJECTIVE: Ambulance patient offload time (APOT) also known colloquially as "Wall time" has been described in various jurisdictions but seems to be highly variable. Any attempt to improve APOT requires the use of common definitions and standard methodology to measure the extent of the problem. METHODS: An Ambulance Offload Delay Task Force in California developed a set of standard definitions and methodology to measure APOT for transported 9-1-1 patients. It is defined as the time "interval between the arrival of an ambulance at an emergency department and the time that the patient is transferred to an ED gurney, bed, chair or other acceptable location and the ED assumes responsibility for care of the patient." Local EMS agencies voluntarily reported data according to the standard methodology to the California EMS Authority (State agency). RESULTS: Data were reported for 9-1-1 transports during 2017 from 9 of 33 local EMS Agencies in California that comprise 37 percent of the state population. These represent 830,637 ambulance transports to 126 hospitals. APOT shows significant variation by EMS agency with half of the agencies demonstrating significant delays. Offload times vary markedly by hospital as well as by region. Three-fourths of hospitals detained EMS crews more than one hour, 40% more than two hours, and one-third delayed EMS return to service by more than three hours. CONCLUSION: This first step to address offload delays in California consists of standardized definitions for data collection to address the significant variability inherent in obtaining data from 33 local agencies, hundreds of EMS provider agencies, and 320 acute care hospital Emergency Departments that receive 9-1-1 ambulance transports. The first year of standardized data collection of ambulance patient offload times revealed significant ambulance patient offload time delays that are not distributed uniformly, resulting in a substantial financial burden for some EMS providers in California.


Asunto(s)
Ambulancias , Benchmarking , Eficiencia Organizacional , Servicios Médicos de Urgencia , Hospitalización , Transporte de Pacientes/normas , Ambulancias/estadística & datos numéricos , California , Servicios Médicos de Urgencia/estadística & datos numéricos , Servicio de Urgencia en Hospital/estadística & datos numéricos , Humanos , Factores de Tiempo
15.
Thorax ; 73(11): 1041-1048, 2018 11.
Artículo en Inglés | MEDLINE | ID: mdl-29899038

RESUMEN

BACKGROUND: Secondhand smoke (SHS) exposures have been linked to asthma-related outcomes but quantitative dose-responses using biomarkers of exposure have not been widely reported. OBJECTIVES: Assess dose-response relationships between plasma cotinine-determined SHS exposure and asthma outcomes in minority children, a vulnerable population exposed to higher levels of SHS and under-represented in the literature. METHODS: We performed analyses in 1172 Latino and African-American children with asthma from the mainland USA and Puerto Rico. We used logistic regression to assess relationships of cotinine levels ≥0.05 ng/mL with asthma exacerbations (defined as asthma-related hospitalisations, emergency room visits or oral steroid prescription) in the previous year and asthma control. The shape of dose-response relationships was assessed using a continuous exposure variable in generalised additive logistic models with penalised splines. RESULTS: The OR for experiencing asthma exacerbations in the previous year for cotinine levels ≥0.05 ng/mL, compared with <0.05 ng/mL, was 1.40 (95% CI 1.03 to 1.89), while the OR for poor asthma control was 1.53 (95% CI 1.12 to 2.13). Analyses for dose-response relationships indicated increasing odds of asthma outcomes related with increasing exposure, even at cotinine levels associated with light SHS exposures. CONCLUSIONS: Exposure to SHS was associated with higher odds of asthma exacerbations and having poorly controlled asthma with an increasing dose-response even at low levels of exposure. Our results support the conclusion that there are no safe levels of SHS exposures.


Asunto(s)
Asma/etnología , Negro o Afroamericano , Hispánicos o Latinos , Medición de Riesgo/métodos , Contaminación por Humo de Tabaco/efectos adversos , Adolescente , Asma/etiología , Niño , Femenino , Humanos , Incidencia , Masculino , Factores de Riesgo , Estados Unidos/epidemiología , Adulto Joven
16.
Ecology ; 99(9): 1988-1998, 2018 09.
Artículo en Inglés | MEDLINE | ID: mdl-30074614

RESUMEN

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.


Asunto(s)
Latencia en las Plantas , Semillas , Germinación , Humanos , Panamá , Suelo , Síndrome
17.
J Environ Qual ; 47(1): 62-69, 2018 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-29415105

RESUMEN

Soil functional zone management strategies including ridge tillage have been shown to increase in-row (IR) compared with between-row (BR) soil nitrogen (N) availability due to the development of contrasting soil properties and carbon (C) and N cycling processes. However, potential N losses may also increase for IR positions, representing an environmental tradeoff. Although biochar has putative contributions to tightening N cycles, its effect within spatially distinct management zones has not been quantified. This study evaluated the potential for biochar to reduce soil nitrous oxide (NO) emissions and leachate nitrate (NO) concentrations as influenced by changes in soil properties after 5 yr of ridge tillage in a silty clay loam soil. Soil columns for IR and BR positions were treated with and without biochar at 10 Mg ha in a 100-d laboratory incubation ( = 4 replications). Results indicate that biochar increased average daily NO emissions in IR by 30% but decreased them by 39% in BR. In both positions, biochar decreased NO concentrations in soil solution and leachate by 11 to 20% and 10 to 15%, respectively. Our findings suggest that long-term changes in soil C and N cycling processes may increase the potential for NO emissions in IR compared with BR positions. Although most biochar studies have not accounted for within-field soil variability, our results indicate that biochar may differentially affect soil NO emissions depending on spatially distinct soil management history. Findings from this laboratory study stress the need for field research evaluating spatial differences in biochar NO mitigation potential.


Asunto(s)
Carbón Orgánico/química , Nitrógeno/química , Fertilizantes , Suelo/química
18.
Field Crops Res ; 228: 93-101, 2018 Nov 01.
Artículo en Inglés | MEDLINE | ID: mdl-30739981

RESUMEN

Nepal is at a crossroads of diminishing farm-labor and inadequate investment into farming operations that, among other factors, have stagnated domestic wheat yield. Cultural and economic constraints have hindered the widespread adoption of more expensive precision agriculture technologies like zero-till that have the capacity to improve labor and farm input efficiencies. To capture the benefits from added precision of application but with the ability to fit within the current semi-mechanized seed bed preparation and tillage system, we introduced a low-cost, chest mounted seed and fertilizer. We found that simple mechanization caused yield efficiencies to be positive and significant for nitrogen and phosphate. Seed rates using this method were positively associated with seedling density. This led to both yield and profit being more predictable for farmers. Conversely, hand-applied inputs caused a disassociation between inputs and end of season yield and therefore added a large measure of risk to their farming operations.

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