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1.
Oecologia ; 204(2): 257-277, 2024 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-38326516

RESUMEN

We compared three sets of highly resolved food webs with and without parasites for a subarctic lake system corresponding to its pelagic and benthic compartments and the whole-lake food web. Key topological food-web metrics were calculated for each set of compartments to explore the role parasites play in food-web topology in these highly contrasting webs. After controlling for effects from differences in web size, we observed similar responses to the addition of parasites in both the pelagic and benthic compartments demonstrated by increases in trophic levels, linkage density, connectance, generality, and vulnerability despite the contrasting composition of free-living and parasitic species between the two compartments. Similar effects on food-web topology can be expected with the inclusion of parasites, regardless of the physical characteristics and taxonomic community compositions of contrasting environments. Additionally, similar increases in key topological metrics were found in the whole-lake food web that combines the pelagic and benthic webs, effects that are comparable to parasite food-web analyses from other systems. These changes in topological metrics are a result of the unique properties of parasites as infectious agents and the links they participate in. Trematodes were key contributors to these results, as these parasites have distinct characteristics in aquatic systems that introduce new link types and increase the food web's generality and vulnerability disproportionate to other parasites. Our analysis highlights the importance of incorporating parasites, especially trophically transmitted parasites, into food webs as they significantly alter key topological metrics and are thus essential for understanding an ecosystem's structure and functioning.


Asunto(s)
Ecosistema , Parásitos , Animales , Cadena Alimentaria , Lagos , Alimentos
2.
Exp Cell Res ; 430(1): 113701, 2023 09 01.
Artículo en Inglés | MEDLINE | ID: mdl-37393982

RESUMEN

Exposure of eukaryotic cells to ionizing radiation or clastogenic chemicals leads to formation of DNA double-strand breaks (DSBs). These lesions are also generated internally by chemicals and enzymes, in the absence of exogenous agents, though the sources and consequences of such endogenously generated DSBs remain poorly understood. In the current study, we have investigated the impact of reduced recombinational repair of endogenous DSBs on stress responses, cell morphology and other physical properties of S. cerevisiae (budding yeast) cells. Use of phase contrast and DAPI-based fluorescence microscopy combined with FACS analysis confirmed that recombination-deficient rad52 cell cultures exhibit chronically high levels of G2 phase cells. Cell cycle phase transit times during G1, S and M were similar in WT and rad52 cells, but the length of G2 phase was increased by three-fold in the mutants. rad52 cells were larger than WT in all phases of the cycle and displayed other quantifiable changes in physical characteristics. The high G2 cell phenotype was abolished when DNA damage checkpoint genes, but not spindle assembly checkpoint genes, were co-inactivated with RAD52. Several other RAD52 group mutants (rad51, rad54, rad55, rad57 and rad59) also exhibited the high G2 cell phenotype. The results indicate that recombination deficiency leads to accumulation of unrepaired DSBs during normal mitotic growth that activate a major stress response and produce distinct changes in cellular physiology and morphology.


Asunto(s)
Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Proteínas de Unión al ADN/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Recombinasa Rad51/genética , Recombinasa Rad51/metabolismo , Reparación del ADN , Ciclo Celular/genética , Recombinación Homóloga/genética
3.
Proc Biol Sci ; 290(2000): 20230877, 2023 06 14.
Artículo en Inglés | MEDLINE | ID: mdl-37312554

RESUMEN

Habitat isolation and disturbance are important regulators of biodiversity, yet it remains unclear how these environmental features drive differences in parasite diversity between ecosystems. We test whether the biological communities in an isolated, frequently disturbed marine ecosystem (deep-sea hydrothermal vents) have reduced parasite richness and relatively fewer parasite species with indirect life cycles (ILCs) compared to ecosystems that are less isolated and less disturbed. We surveyed the parasite fauna of the biological community at the 9°50'N hydrothermal vent field on the East Pacific Rise and compared it to similar datasets from a well-connected and moderately disturbed ecosystem (kelp forest) and an isolated and undisturbed ecosystem (atoll sandflat). Parasite richness within host species did not differ significantly between ecosystems, yet total parasite richness in the vent community was much lower due to the low number of predatory fish species. Contrary to expectation, the proportion of ILC parasite species was not lower at vents due to a high richness of trematodes, while other ILC parasite taxa were scarce (nematodes) or absent (cestodes). These results demonstrate the success of diverse parasite taxa in an extreme environment and reinforce the importance of host diversity and food web complexity in governing parasite diversity.


Asunto(s)
Respiraderos Hidrotermales , Parásitos , Animales , Ecosistema , Biodiversidad , Bosques
4.
Diabetes Obes Metab ; 25(5): 1280-1291, 2023 05.
Artículo en Inglés | MEDLINE | ID: mdl-36655410

RESUMEN

AIM: To investigate the effects of pyridoxamine (PM), a B6 vitamer and dicarbonyl scavenger, on glycation and a large panel of metabolic and vascular measurements in a randomized double-blind placebo-controlled trial in abdominally obese individuals. MATERIALS AND METHODS: Individuals (54% female; mean age 50 years; mean body mass index 32 kg/m2 ) were randomized to an 8-week intervention with either placebo (n = 36), 25 mg PM (n = 36) or 200 mg PM (n = 36). We assessed insulin sensitivity, ß-cell function, insulin-mediated microvascular recruitment, skin microvascular function, flow-mediated dilation, and plasma inflammation and endothelial function markers. PM metabolites, dicarbonyls and advanced glycation endproducts (AGEs) were measured using ultra-performance liquid chromatography tandem mass spectrometry. Treatment effects were evaluated by one-way ANCOVA. RESULTS: In the high PM dose group, we found a reduction of plasma methylglyoxal (MGO) and protein-bound Nδ-(5-hydro-5-methyl-4-imidazolon-2-yl)-ornithine (MG-H1), as compared to placebo. We found a reduction of the endothelial dysfunction marker soluble vascular cell adhesion molecule-1 (sVCAM-1) in the low and high PM dose group and of soluble intercellular adhesion molecule-1 (sICAM-1) in the high PM dose, as compared to placebo. We found no treatment effects on insulin sensitivity, vascular function or other functional outcome measurements. CONCLUSIONS: This study shows that PM is metabolically active and reduces MGO, AGEs, sVCAM-1 and sICAM-1, but does not affect insulin sensitivity and vascular function in abdominally obese individuals. The reduction in adhesion markers is promising because these are important in the pathogenesis of endothelial damage and atherosclerosis.


Asunto(s)
Resistencia a la Insulina , Humanos , Femenino , Persona de Mediana Edad , Masculino , Piruvaldehído , Reacción de Maillard , Piridoxamina/farmacología , Piridoxamina/uso terapéutico , Productos Finales de Glicación Avanzada/metabolismo , Óxido de Magnesio , Obesidad
5.
J Eur Acad Dermatol Venereol ; 36(8): 1359-1366, 2022 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-35412677

RESUMEN

BACKGROUND: Cutaneous neurofibromas (cNF), present in 95% of individuals with neurofibromatosis 1 (NF1), are considered as one of the greatest medical burden because of physical disfigurement. No specific score evaluates their impact on quality of life (QoL). OBJECTIVE: To develop a specific score assessing cNF-related QoL. METHODS: Through a multidisciplinary workshop including 10 patients, 3 expert-in-NF1 physicians, 3 health care workers (nurses and psychologist) and 1 methodologist, the French version of the Skindex-16 was modified by adding 3 items. The new cNF-Skindex was validated among patients with NF1 recruited in the ComPaRe online cohort, in France (N = 284). Construct validity was assessed by comparing it with the EQ-5D-5L, its visual analogue scale and the MYMOP2 and by assessing its association with patients' characteristics. Reliability was assessed by a test-retest. An English version of the tool was developed using a back-forward translation. RESULTS: A total of 228 individuals with NF1, with cNF answered the 19-item questionnaire. These items fitted into 3 domains: emotions, symptoms, functioning. One was dropped during analysis because >90% responders were not concerned. The cNF-Skindex significantly correlated with the EQ-5D-5L (N = 193) and MYMOP2 (N = 210) indicating good external validity: rs 0.38 (P < 0.001), and 0.58 (P < 0.001), respectively. Having >50 cNF was the only independent variable associated with the total score cNF-Skindex (ß = 15.88, 95%CI 6.96-24.81, P = 0.001), and with the 3 sub-scores: 'functioning' (ß = 2.65, 95%CI 0.71-4.59, P = 0.008), 'emotions' (ß = 17.03, 95%CI 4.11-29.96, P = 0.010) and 'symptoms' (ß = 3.90, 95%CI 1.95-5.85, P < 0.001). Test-retest reliability (N = 133) found an ICC at 0.96 demonstrating good reproducibility. CONCLUSION: The cNF-Skindex demonstrated excellent psychometric properties. The global and sub-scores were increased with higher number of cNF arguing for its use in further trials aiming to reduce their number or prevent their development. Cross-cultural validation and evaluation of its responsiveness are the next steps.


Asunto(s)
Neurofibroma , Neurofibromatosis 1 , Neoplasias Cutáneas , Adulto , Humanos , Neurofibromatosis 1/psicología , Psicometría , Calidad de Vida/psicología , Reproducibilidad de los Resultados , Encuestas y Cuestionarios , Traducciones
6.
Proc Natl Acad Sci U S A ; 116(46): 23182-23191, 2019 11 12.
Artículo en Inglés | MEDLINE | ID: mdl-31659025

RESUMEN

Recently, the World Health Organization recognized that efforts to interrupt schistosomiasis transmission through mass drug administration have been ineffective in some regions; one of their new recommended strategies for global schistosomiasis control emphasizes targeting the freshwater snails that transmit schistosome parasites. We sought to identify robust indicators that would enable precision targeting of these snails. At the site of the world's largest recorded schistosomiasis epidemic-the Lower Senegal River Basin in Senegal-intensive sampling revealed positive relationships between intermediate host snails (abundance, density, and prevalence) and human urogenital schistosomiasis reinfection (prevalence and intensity in schoolchildren after drug administration). However, we also found that snail distributions were so patchy in space and time that obtaining useful data required effort that exceeds what is feasible in standard monitoring and control campaigns. Instead, we identified several environmental proxies that were more effective than snail variables for predicting human infection: the area covered by suitable snail habitat (i.e., floating, nonemergent vegetation), the percent cover by suitable snail habitat, and size of the water contact area. Unlike snail surveys, which require hundreds of person-hours per site to conduct, habitat coverage and site area can be quickly estimated with drone or satellite imagery. This, in turn, makes possible large-scale, high-resolution estimation of human urogenital schistosomiasis risk to support targeting of both mass drug administration and snail control efforts.


Asunto(s)
Bulinus , Vectores de Enfermedades , Ecosistema , Esquistosomiasis/transmisión , Animales , Humanos , Densidad de Población , Imágenes Satelitales , Esquistosomiasis/epidemiología , Senegal/epidemiología , Análisis Espacial
7.
Int J Mol Sci ; 23(10)2022 May 10.
Artículo en Inglés | MEDLINE | ID: mdl-35628138

RESUMEN

Dietary advanced glycation endproducts (AGEs), abundantly present in Westernized diets, are linked to negative health outcomes, but their impact on the gut microbiota has not yet been well investigated in humans. We investigated the effects of a 4-week isocaloric and macronutrient-matched diet low or high in AGEs on the gut microbial composition of 70 abdominally obese individuals in a double-blind parallel-design randomized controlled trial (NCT03866343). Additionally, we investigated the cross-sectional associations between the habitual intake of dietary dicarbonyls, reactive precursors to AGEs, and the gut microbial composition, as assessed by 16S rRNA amplicon-based sequencing. Despite a marked percentage difference in AGE intake, we observed no differences in microbial richness and the general community structure. Only the Anaerostipes spp. had a relative abundance >0.5% and showed differential abundance (0.5 versus 1.11%; p = 0.028, after low- or high-AGE diet, respectively). While the habitual intake of dicarbonyls was not associated with microbial richness or a general community structure, the intake of 3-deoxyglucosone was especially associated with an abundance of several genera. Thus, a 4-week diet low or high in AGEs has a limited impact on the gut microbial composition of abdominally obese humans, paralleling its previously observed limited biological consequences. The effects of dietary dicarbonyls on the gut microbiota composition deserve further investigation.


Asunto(s)
Microbioma Gastrointestinal , Productos Finales de Glicación Avanzada , Obesidad , Estudios Transversales , Dieta , Método Doble Ciego , Productos Finales de Glicación Avanzada/administración & dosificación , Humanos , Obesidad/dietoterapia , Obesidad/microbiología , ARN Ribosómico 16S/genética
8.
Proc Biol Sci ; 288(1945): 20203036, 2021 02 24.
Artículo en Inglés | MEDLINE | ID: mdl-33622132

RESUMEN

The abundances of free-living species have changed dramatically in recent decades, but little is known about change in the abundance of parasitic species. We investigated whether populations of several parasites have shifted over time in two shore crab hosts, Hemigrapsus oregonensis and Hemigrapsus nudus, by comparing the prevalence and abundance of three parasite taxa in a historical dataset (1969-1970) to contemporary parasite abundance (2018-2020) for hosts collected from 11 intertidal sites located from Oregon, USA, to British Columbia, Canada. Our data suggest that the abundance of the parasitic isopod Portunion conformis has varied around a stable mean for the past 50 years. No change over time was observed for larval acanthocephalans. However, larval microphallid trematodes increased in prevalence over time among H. oregonensis hosts, from a mean of 8.4-61.8% between the historical and contemporary time points. The substantial increase in the prevalence of larval microphallid trematodes could be owing to increased abundances of their bird final hosts, increased production of parasite infective stages by snail intermediate hosts or both. Our study highlights the variability among parasite species in their temporal trajectories of change.


Asunto(s)
Braquiuros , Parásitos , Trematodos , Animales , Colombia Británica/epidemiología , Interacciones Huésped-Parásitos , América del Norte , Oregon
9.
Conserv Biol ; 34(3): 721-732, 2020 06.
Artículo en Inglés | MEDLINE | ID: mdl-31702070

RESUMEN

Conservation biology was founded on the idea that efforts to save nature depend on a scientific understanding of how it works. It sought to apply ecological principles to conservation problems. We investigated whether the relationship between these fields has changed over time through machine reading the full texts of 32,000 research articles published in 16 ecology and conservation biology journals. We examined changes in research topics in both fields and how the fields have evolved from 2000 to 2014. As conservation biology matured, its focus shifted from ecology to social and political aspects of conservation. The 2 fields diverged and now occupy distinct niches in modern science. We hypothesize this pattern resulted from increasing recognition that social, economic, and political factors are critical for successful conservation and possibly from rising skepticism about the relevance of contemporary ecological theory to practical conservation.


Relaciones entre la Biología de la Conservación y la Ecología Mostradas a través de la Lectura Mediante Máquina de 32,000 Artículos Resumen La biología de la conservación se fundó a partir de la idea de que los esfuerzos para salvar a la naturaleza dependen del entendimiento científico de cómo funciona. La biología de la conservación buscaba aplicar los principios ecológicos a los problemas de conservación. En este trabajo investigamos si la relación entre estos ámbitos ha cambiado con el tiempo al realizar una lectura mediante máquina de 32,000 textos completos de artículos de investigación publicados en 16 revistas sobre ecología y biología de la conservación. También examinamos los cambios en los temas de investigación en ambos ámbitos y cómo éstos han evolucionado desde el año 2000 hasta el 2014. Conforme ha madurado la biología de la conservación, su enfoque se ha movido de los aspectos ecológicos de la conservación a los aspectos políticos y sociales. La ecología y la biología de la conservación se han separado y ahora ocupan nichos distintos dentro de la ciencia moderna. Nuestra hipótesis considera que este patrón resultó de incrementar el reconocimiento de que los factores sociales, económicos y políticos son muy importantes para una conservación exitosa. Posiblemente el patrón también proviene del creciente escepticismo acerca de la relevancia que la teoría ecológica contemporánea tiene para la conservación en práctica.


Asunto(s)
Conservación de los Recursos Naturales , Ecología
10.
Parasitology ; 146(3): 407-412, 2019 03.
Artículo en Inglés | MEDLINE | ID: mdl-30301482

RESUMEN

The rocky intertidal zone has a long history of ecological study with barnacles frequently serving as a model system to explore foundational theories. Parasites are often ignored in community ecology studies, and this particularly holds for true for the rocky intertidal zone. We explore the role of the isopod parasite, Hemioniscus balani, on its host, the acorn barnacle, Chthamalus fissus. We use the currencies of biomass and reproduction measured at the individual level, then applied to the population level, to evaluate the importance of this parasite to barnacle populations. We found H. balani can comprise substantial biomass in 'apparent' barnacle populations, sometimes even equaling barnacle biomass. Additionally, parasite reproduction sometimes matched barnacle reproduction. Thus, parasites divert substantial energy flow from the barnacle population and to near-shore communities in the form of parasite larvae. Parasites appeared to decrease barnacle reproduction per area. Potentially, this parasite may control barnacle populations, depending on the extent to which heavily infected barnacle populations contribute to barnacle populations at larger scales. These findings regarding the importance of a particular parasite for host population dynamics in this well studied ecosystem call for the integration of disease dynamics into community ecological studies of the rocky intertidal zone.


Asunto(s)
Biomasa , Interacciones Huésped-Parásitos , Isópodos/fisiología , Thoracica/fisiología , Animales , California , Ecosistema , Dinámica Poblacional , Reproducción , Thoracica/parasitología , Olas de Marea
11.
Ann Oncol ; 29(1): 92-100, 2018 01 01.
Artículo en Inglés | MEDLINE | ID: mdl-29045541

RESUMEN

In addition to liver disorders, hepatitis C virus (HCV) is also associated with extrahepatic immune manifestations and B-cell non-Hodgkin lymphoma (NHL), especially marginal zone lymphoma, de novo or transformed diffuse large B-cell lymphoma and to a lesser extent, follicular lymphoma. Epidemiological data and clinical observations argue for an association between HCV and lymphoproliferative disorders. The causative role of HCV in NHL has been further supported by the response to antiviral therapy. Pathophysiological processes at stake leading from HCV infection to overt lymphoma still need to be further elucidated. Based on reported biological studies, several mechanisms of transformation seem however to emerge. A strong body of evidence supports the hypothesis of an indirect transformation mechanism by which sustained antigenic stimulation leads from oligoclonal to monoclonal expansion and sometimes to frank lymphoma, mostly of marginal zone subtype. By infecting lymphocytes, HCV could play a direct role in cellular transformation, particularly in de novo large B-cell lymphoma. Finally, HCV is associated with follicular lymphoma in a subset of patients. In this setting, it may be hypothesized that inflammatory cytokines stimulate proliferation and transformation of IgH-BCL2 clones that are increased during chronic HCV infection. Unraveling the pathogenesis of HCV-related B-cell lymphoproliferation is of prime importance to optimize therapeutic strategies, especially with the recent development of new direct-acting antiviral drugs.


Asunto(s)
Hepatitis C Crónica/epidemiología , Hepatitis C Crónica/patología , Linfoma de Células B/epidemiología , Linfoma de Células B/virología , Animales , Antivirales/uso terapéutico , Transformación Celular Neoplásica , Hepacivirus/aislamiento & purificación , Hepatitis C Crónica/tratamiento farmacológico , Humanos , Linfoma de Células B/tratamiento farmacológico , Linfoma de Células B/patología
12.
Proc Natl Acad Sci U S A ; 112(31): 9650-5, 2015 Aug 04.
Artículo en Inglés | MEDLINE | ID: mdl-26195752

RESUMEN

Eliminating human parasitic disease often requires interrupting complex transmission pathways. Even when drugs to treat people are available, disease control can be difficult if the parasite can persist in nonhuman hosts. Here, we show that restoration of a natural predator of a parasite's intermediate hosts may enhance drug-based schistosomiasis control. Our study site was the Senegal River Basin, where villagers suffered a massive outbreak and persistent epidemic after the 1986 completion of the Diama Dam. The dam blocked the annual migration of native river prawns (Macrobrachium vollenhoveni) that are voracious predators of the snail intermediate hosts for schistosomiasis. We tested schistosomiasis control by reintroduced river prawns in a before-after-control-impact field experiment that tracked parasitism in snails and people at two matched villages after prawns were stocked at one village's river access point. The abundance of infected snails was 80% lower at that village, presumably because prawn predation reduced the abundance and average life span of latently infected snails. As expected from a reduction in infected snails, human schistosomiasis prevalence was 18 ± 5% lower and egg burden was 50 ± 8% lower at the prawn-stocking village compared with the control village. In a mathematical model of the system, stocking prawns, coupled with infrequent mass drug treatment, eliminates schistosomiasis from high-transmission sites. We conclude that restoring river prawns could be a novel contribution to controlling, or eliminating, schistosomiasis.


Asunto(s)
Biomphalaria/parasitología , Palaemonidae/fisiología , Ríos , Esquistosomiasis/parasitología , Esquistosomiasis/transmisión , Adolescente , Adulto , Animales , Niño , Preescolar , Femenino , Interacciones Huésped-Parásitos , Humanos , Masculino , Persona de Mediana Edad , Modelos Biológicos , Conducta Predatoria , Prevalencia , Schistosoma/fisiología , Esquistosomiasis/epidemiología , Adulto Joven
13.
Emerg Infect Dis ; 23(8): 1397-1399, 2017 08.
Artículo en Inglés | MEDLINE | ID: mdl-28726612

RESUMEN

Baylisascaris procyonis (raccoon roundworm) infection is common in raccoons and can cause devastating pathology in other animals, including humans. Limited information is available on the frequency of asymptomatic human infection. We tested 150 adults from California, USA, for B. procyonis antibodies; 11 were seropositive, suggesting that subclinical infection does occur.


Asunto(s)
Infecciones por Ascaridida/epidemiología , Ascarídidos/inmunología , Animales , Infecciones por Ascaridida/historia , Infecciones por Ascaridida/inmunología , California/epidemiología , Heces/parasitología , Femenino , Historia del Siglo XXI , Humanos , Masculino , Prevalencia , Mapaches , Estudios Seroepidemiológicos , Zoonosis
14.
Eur J Clin Invest ; 47(2): 137-148, 2017 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-28036114

RESUMEN

BACKGROUND: In end-stage renal disease (ESRD), coronary artery calcification (CAC) and inflammation contribute to cardiovascular disease (CVD). Statins do not improve survival in patients with ESRD, and their effect on vascular calcification is unclear. We explored associations between CAC, inflammatory biomarkers, statins and mortality in ESRD. MATERIALS AND METHODS: In 240 patients with ESRD (63% males; median age 56 years) from cohorts including 86 recipients of living donor kidney transplant (LD-Rtx), 96 incident dialysis patients and 58 prevalent peritoneal dialysis patients, associations of CAC score (Agatston Units, AUs), interleukin-6 (IL-6) with high-sensitivity C-reactive protein (hsCRP), tumour necrosis factor (TNF), use of statins and all-cause mortality were analysed. Cardiac CT was repeated in 35 patients after 1·5 years of renal replacement therapy. In vitro, human vascular smooth muscle cells (hVSMCs) were used to measure vitamin K metabolism. RESULTS: Among 240 patients, 129 (53%) had a CAC score > 100 AUs. Multivariate analysis revealed that independent predictors of 1-SD higher CAC score were age, male gender, diabetes and use of statins. The association between CAC score and mortality remained significant after adjustment for age, gender, diabetes, CVD, use of statins, protein-energy wasting and inflammation. Repeated CAC imaging in 35 patients showed that statin therapy was associated with greater progression of CAC. In vitro synthesis of menaquinone-4 by hVSMCs was significantly impaired by statins. CONCLUSION: Elevated CAC score is a mortality risk factor in ESRD independent of inflammation. Future studies should resolve if statins promote vascular calcification and inhibition of vitamin K synthesis in the uremic milieu.


Asunto(s)
Enfermedad de la Arteria Coronaria/inducido químicamente , Inhibidores de Hidroximetilglutaril-CoA Reductasas/efectos adversos , Fallo Renal Crónico/complicaciones , Calcificación Vascular/inducido químicamente , Adulto , Anciano , Biomarcadores/metabolismo , Enfermedad de la Arteria Coronaria/mortalidad , Femenino , Humanos , Estimación de Kaplan-Meier , Fallo Renal Crónico/mortalidad , Masculino , Persona de Mediana Edad , Músculo Liso Vascular/metabolismo , Calcificación Vascular/mortalidad , Vitamina K/metabolismo
15.
Parasitology ; 144(7): 917-922, 2017 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-28270243

RESUMEN

While parasites serve as prey, it is unclear how the spatial distribution of parasite predators provides transmission control and influences patterns of parasitism. Because many of its organisms are sessile, the rocky intertidal zone is a valuable but little used system to understand spatial patterns of parasitism and elucidate the underlying mechanisms driving these patterns. Sea anemones and barnacles are important space competitors in the rocky intertidal zone along the Pacific coast of North America. Anemones are voracious, indiscriminate predators; thus, they may intercept infectious stages of parasites before they reach a host. We investigate whether a sea anemone protects an associated barnacle from parasitism by Hemioniscus balani, an isopod parasitic castrator. At Coal Oil Point, Santa Barbara, California USA, 29% of barnacles were within 1 cm from an anemone at the surveyed tidal height. Barnacles associated with anemones had reduced parasite prevalence and higher reproductive productivity than those remote from sea anemones. In the laboratory, anemones readily consumed the transmission stage of the parasite. Hence, anemone consumption of parasite transmission stages may provide a mechanism by which community context regulates parasite prevalence at a local scale. Our results suggest predation may be an important process providing parasite transmission control.


Asunto(s)
Interacciones Huésped-Parásitos , Isópodos/fisiología , Conducta Predatoria , Anémonas de Mar/parasitología , Thoracica/parasitología , Animales , California , Reproducción
16.
Parasitology ; 144(5): 662-668, 2017 04.
Artículo en Inglés | MEDLINE | ID: mdl-27928977

RESUMEN

The 'crowding effect' is a result of competition by parasites within a host for finite resources. Typically, the severity of this effect increases with increasing numbers of parasites within a host and manifests in reduced body size and thus fitness. Evidence for the crowding effect is mixed - while some have found negative effects, others have found a positive effect of increased parasite load on parasite fitness. Parasites are consumers with diverse trophic strategies reflected in their life history traits. These distinctions are useful to predict the effects of crowding. We studied a parasitic castrator, a parasite that usurps host reproductive energy and renders the host sterile. Parasitic castrators typically occur as single infections within hosts. With multiple parasitic castrators, we expect strong competition and evidence of crowding. We directly assess the effect of crowding on reproductive success in a barnacle population infected by a unique parasitic castrator, Hemioniscus balani, an isopod parasite that infects and blocks reproduction of barnacles. We find (1) strong evidence of crowding in double infections, (2) increased frequency of double infections in larger barnacle hosts with more resources and (3) perfect compensation in egg production, supporting strong space limitation. Our results document that the effects of crowding are particularly severe for this parasitic castrator, and may be applicable to other castrators that are also resource or space limited.


Asunto(s)
Interacciones Huésped-Parásitos , Isópodos/fisiología , Thoracica/parasitología , Animales , Tamaño Corporal , Ecología , Femenino , Masculino , Óvulo , Reproducción , Thoracica/crecimiento & desarrollo , Thoracica/fisiología
17.
PLoS Biol ; 11(6): e1001579, 2013.
Artículo en Inglés | MEDLINE | ID: mdl-23776404

RESUMEN

Comparative research on food web structure has revealed generalities in trophic organization, produced simple models, and allowed assessment of robustness to species loss. These studies have mostly focused on free-living species. Recent research has suggested that inclusion of parasites alters structure. We assess whether such changes in network structure result from unique roles and traits of parasites or from changes to diversity and complexity. We analyzed seven highly resolved food webs that include metazoan parasite data. Our analyses show that adding parasites usually increases link density and connectance (simple measures of complexity), particularly when including concomitant links (links from predators to parasites of their prey). However, we clarify prior claims that parasites "dominate" food web links. Although parasites can be involved in a majority of links, in most cases classic predation links outnumber classic parasitism links. Regarding network structure, observed changes in degree distributions, 14 commonly studied metrics, and link probabilities are consistent with scale-dependent changes in structure associated with changes in diversity and complexity. Parasite and free-living species thus have similar effects on these aspects of structure. However, two changes point to unique roles of parasites. First, adding parasites and concomitant links strongly alters the frequency of most motifs of interactions among three taxa, reflecting parasites' roles as resources for predators of their hosts, driven by trophic intimacy with their hosts. Second, compared to free-living consumers, many parasites' feeding niches appear broader and less contiguous, which may reflect complex life cycles and small body sizes. This study provides new insights about generic versus unique impacts of parasites on food web structure, extends the generality of food web theory, gives a more rigorous framework for assessing the impact of any species on trophic organization, identifies limitations of current food web models, and provides direction for future structural and dynamical models.


Asunto(s)
Biodiversidad , Cadena Alimentaria , Parásitos/fisiología , Animales , Modelos Lineales , Modelos Biológicos , Probabilidad , Especificidad de la Especie
18.
Biol Lett ; 12(7)2016 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-27436119

RESUMEN

Nearly half of all animals may have a parasitic lifestyle, yet the number of transitions to parasitism and their potential for species diversification remain unresolved. Based on a comprehensive survey of the animal kingdom, we find that parasitism has independently evolved at least 223 times in just 15 phyla, with the majority of identified independent parasitic groups occurring in the Arthropoda, at or below the level of Family. Metazoan parasitology is dominated by the study of helminthes; however, only 20% of independently derived parasite taxa belong to those groups, with numerous transitions also seen in Mollusca, Rotifera, Annelida and Cnidaria. Parasitism is almost entirely absent from deuterostomes, and although worm-like morphology and host associations are widespread across Animalia, the dual symbiotic and trophic interactions required for parasitism may constrain its evolution from antecedent consumer strategies such as generalist predators and filter feeders. In general, parasitic groups do not differ from their free-living relatives in their potential for speciation. However, the 10 largest parasitic clades contain 90% of described parasitic species, or perhaps 40% of all animal species. Hence, a substantial fraction of animal diversity on the Earth arose following these few transitions to a parasitic trophic strategy.


Asunto(s)
Evolución Biológica , Parásitos/clasificación , Animales , Filogenia , Simbiosis
19.
Nano Lett ; 15(4): 2671-8, 2015 Apr 08.
Artículo en Inglés | MEDLINE | ID: mdl-25714564

RESUMEN

Novel lithium metal polymer solid state batteries with nano C-LiFePO4 and nano Li1.2V3O8 counter-electrodes (average particle size 200 nm) were studied for the first time by in situ SEM and impedance during cycling. The kinetics of Li-motion during cycling is analyzed self-consistently together with the electrochemical properties. We show that the cycling life of the nano Li1.2V3O8 is limited by the dissolution of the vanadium in the electrolyte, which explains the choice of nano C-LiFePO4 (1300 cycles at 100% DOD): with this olivine, no dissolution is observed. In combination with lithium metal, at high loading and with a stable SEI an ultrahigh energy density battery was thus newly developed in our laboratory.

20.
J Proteome Res ; 14(11): 4603-9, 2015 Nov 06.
Artículo en Inglés | MEDLINE | ID: mdl-26381038

RESUMEN

Many mutations and allelic variants are known that influence the rate at which animals age, but when in life do such variants diverge from normal patterns of aging? Is this divergence visible in their physiologies? To investigate these questions, we have used (1)H NMR spectroscopy to study how the metabolome of the nematode Caenorhabditis elegans changes as it grows older. We identify a series of metabolic changes that, collectively, predict the age of wild-type worms. We then show that long-lived mutant daf-2(m41) worms are metabolically youthful compared to wild-type worms, but that this relative youth only appears in middle age. Finally, we show that metabolic age predicts the timing and magnitude of differences in age-specific mortality between these strains. Thus, the future mortality of these two genotypes can be predicted long before most of the worms die.


Asunto(s)
Envejecimiento/metabolismo , Aminoácidos/metabolismo , Proteínas de Caenorhabditis elegans/metabolismo , Caenorhabditis elegans/metabolismo , Metaboloma , Receptor de Insulina/metabolismo , Trehalosa/metabolismo , Envejecimiento/genética , Aminoácidos/farmacología , Animales , Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/genética , Regulación de la Expresión Génica , Genotipo , Modelos Lineales , Longevidad/genética , Espectroscopía de Resonancia Magnética , Mutación , Receptor de Insulina/genética , Trehalosa/farmacología
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