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1.
Nat Commun ; 13(1): 4990, 2022 08 25.
Artículo en Inglés | MEDLINE | ID: mdl-36008387

RESUMEN

The ratio of predator-to-prey biomass is a key element of trophic structure that is typically investigated from a food chain perspective, ignoring channels of energy transfer (e.g. omnivory) that may govern community structure. Here, we address this shortcoming by characterising the biomass structure of 141 freshwater, marine and terrestrial food webs, spanning a broad gradient in community biomass. We test whether sub-linear scaling between predator and prey biomass (a potential signal of density-dependent processes) emerges within ecosystem types and across levels of biological organisation. We find a consistent, sub-linear scaling pattern whereby predator biomass scales with the total biomass of their prey with a near ¾-power exponent within food webs - i.e. more prey biomass supports proportionally less predator biomass. Across food webs, a similar sub-linear scaling pattern emerges between total predator biomass and the combined biomass of all prey within a food web. These general patterns in trophic structure are compatible with a systematic form of density dependence that holds among complex feeding interactions across levels of organization, irrespective of ecosystem type.


Asunto(s)
Ecosistema , Cadena Alimentaria , Animales , Biomasa , Agua Dulce , Conducta Predatoria
2.
Ecol Lett ; 25(5): 1225-1236, 2022 May.
Artículo en Inglés | MEDLINE | ID: mdl-35286010

RESUMEN

Despite intensive research on species dissimilarity patterns across communities (i.e. ß-diversity), we still know little about their implications for variation in food-web structures. Our analyses of 50 lake and 48 forest soil communities show that, while species dissimilarity depends on environmental and spatial gradients, these effects are only weakly propagated to the networks. Moreover, our results show that species and food-web dissimilarities are consistently correlated, but that much of the variation in food-web structure across spatial, environmental, and species gradients remains unexplained. Novel food-web assembly models demonstrate the importance of biotic filtering during community assembly by (1) the availability of resources and (2) limiting similarity in species' interactions to avoid strong niche overlap and thus competitive exclusion. This reveals a strong signature of biotic filtering processes during local community assembly, which constrains the variability in structural food-web patterns across local communities despite substantial turnover in species composition.


Asunto(s)
Biodiversidad , Bosques , Ecosistema , Cadena Alimentaria , Suelo
3.
Oecologia ; 196(1): 195-209, 2021 May.
Artículo en Inglés | MEDLINE | ID: mdl-33852071

RESUMEN

Forest soil and litter is inhabited by a diverse community of animals, which directly and indirectly rely on dead organic matter as habitat and food resource. However, community composition may be driven by biotic or abiotic forces, and these vary with changes in habitat structure and resource supply associated with forest land use. To evaluate these changes, we compiled comprehensive data on the species composition of soil animal communities and environmental factors in forest types varying in land-use intensity in each of three regions in Germany, i.e., coniferous, young managed, old managed, and unmanaged beech forests. Coniferous forests featured high amounts of leaf litter and low microbial biomass concentrations contrasting in particular unmanaged beech forests. However, soil animal diversity and functional community composition differed little between forest types, indicating resilience against disturbance and forest land use. Structural equation modelling suggested that despite a significant influence of forest management on resource abundance and quality, the biomass of most soil fauna functional groups was not directly affected by forest management or resource abundance/quality, potentially because microorganisms hamper the propagation of nutrients to higher trophic levels. Instead, detritivore biomass depended heavily on soil pH. Macrofauna decomposers thrived at high pH, whereas mesofauna decomposers benefitted from low soil pH, but also from low biomass of macrofauna decomposers, potentially due to habitat modification by macrofauna decomposers. The strong influence of soil pH shows that decomposer communities are structured predominantly by regional abiotic factors exceeding the role of local biotic factors such as forest type.


Asunto(s)
Cadena Alimentaria , Suelo , Animales , Biodiversidad , Bosques , Alemania , Microbiología del Suelo
4.
R Soc Open Sci ; 7(4): 200100, 2020 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-32431901

RESUMEN

Nutrition is the single most important factor for individual's growth and reproduction. Consequently, the inability to reach the nutritional optimum imposes severe consequences for animal fitness. Yet, under natural conditions, organisms may face a mixture of stressors that can modulate the effects of nutritional asymmetry. For instance, stressful environments caused by intense interaction with conspecifics. Here, we subjected the house cricket Acheta domesticus to (i) either of two types of diet that have proved to affect cricket performance and (ii) simultaneously manipulated their social environment throughout their complete life cycle. We aimed to track sex-specific consequences for multiple traits during insect development throughout all life stages. Both factors affected critical life-history traits with potential population-level consequences: diet composition induced strong effects on insect development time, lifespan and fitness, while the social environment affected the number of nymphs that completed development, food consumption and whole-body lipid content. Additionally, both factors interactively determined female body mass. Our results highlight that insects may acquire and invest resources in a different manner when subjected to an intense interaction with conspecifics or when isolated. Furthermore, while only diet composition affected individual reproductive output, the social environment would determine the number of reproductive females, thus indirectly influencing population performance.

5.
Sci Rep ; 10(1): 7300, 2020 04 29.
Artículo en Inglés | MEDLINE | ID: mdl-32350369

RESUMEN

Widespread application of synthetic pesticides and loss of plant diversity are regarded as significant drivers of current global change. The effects of such phenomena on insect performance have been extensively studied separately, yet the interactions of these two drivers have been poorly explored. Here, we subjected the polyphagous grasshopper Pseudochorthippus parallelus (Zetterstedt, 1821) to a full-lifecycle field experiment with 50 cages containing experimental plant communities differing in grass species richness (2 vs. 8 grass species), half of them treated with a phenoxy herbicide commonly employed to control broadleaf plants in grasslands. We measured plant elemental content as a proxy for plant physiology, and a wide range of insect traits in both female and male grasshoppers. In females, grass diversity increased herbivory, insect nitrogen content and egg load, while herbicide reduced herbivory but increased the number of offspring, likely mediated by altered plant community composition. In males, grass diversity also increased herbivory, had positive effects on fat body, muscle volume and lifespan, and negative effects on body mass. Herbicide negatively affected herbivory in both females and males. Overall, plant diversity and herbicides may shift resource allocation in generalist terrestrial insect herbivores, indicating complex and unexpected effects of human-induced environmental change.


Asunto(s)
Biodiversidad , Cambio Climático , Conducta Alimentaria/efectos de los fármacos , Saltamontes/fisiología , Herbicidas/farmacología , Poaceae , Animales
6.
Interact Cardiovasc Thorac Surg ; 30(5): 699-705, 2020 05 01.
Artículo en Inglés | MEDLINE | ID: mdl-32249892

RESUMEN

OBJECTIVES: Del Nido cardioplegia (DNC) has been shown to be safe in adults with normal coronary arteries who are undergoing valve surgery. This study compared the effects of DNC versus traditional blood-based cardioplegia on postoperative complications in patients who underwent coronary artery bypass grafting (CABG). METHODS: A retrospective analysis was performed on 863 patients who underwent CABG with DNC (n = 420) or control cardioplegia (CC) (n = 443) between 2014 and 2017. The full cohort of DNC and CC recipients, as well as propensity score-matched pairs, was compared regarding preoperative risk variables and outcomes. RESULTS: The DNC and CC groups showed no significant differences in mean cardiopulmonary bypass time (53.09 vs 52.10 min, P = 0.206) or aortic cross-clamp time (32.82 vs 33.28 min, P = 0.967). The groups also showed no difference in operative mortality (2.1% vs 2.5%, P = 0.734); however, DNC use resulted in lower rates of overall infections (1.7% vs 4.3%, P = 0.024), total sternal infections (0.9% vs 3.2%, P = 0.023), postoperative atrial fibrillation (23.8% vs 30.7%, P = 0.023) and postoperative ventricular tachycardia (0.5% vs 3.4%, P = 0.002). A propensity-matching analysis (n = 335 pairs) showed similar statistically significant decreases with DNC. CONCLUSIONS: In this large cohort of CABG patients, DNC was shown as a safe alternative to CC and was associated with lower postoperative dysrhythmia and infection rates. These findings show that DNC is safe and effective in patients whose operative interventions may require only single-dosing cardioplegia; its use in longer cases should be further explored given its low complication rate.


Asunto(s)
Soluciones Cardiopléjicas/farmacología , Puente de Arteria Coronaria/métodos , Enfermedad de la Arteria Coronaria/cirugía , Vasos Coronarios/cirugía , Paro Cardíaco Inducido/métodos , Puntaje de Propensión , Anciano , Estudios de Cohortes , Femenino , Humanos , Masculino , Periodo Posoperatorio , Estudios Retrospectivos
7.
Ecol Evol ; 9(12): 7307-7323, 2019 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-31380052

RESUMEN

Agricultural landscapes are globally dominated by monocultures under intensive management. This is one of the main reasons for biodiversity loss and insect population decline in many regions all over the world. Agroecosystem biodiversity in these areas can be enhanced by cropping system diversification, such as crop rotations. Yet, long-term studies on effects of crop rotations on aboveground agrobiodiversity are lacking. We set up a 10-year long-term crop rotation experiment in Central Germany and monitored the temporal dynamics of aboveground arthropods over a full cultivation period to investigate influence of current and preceding crop identity and cropping system diversification on activity density, species richness, and community structure. We found that species composition was strongly influenced by currently grown crop although effect on arthropods varied between species groups. Especially, winter oilseed rape strongly affects arthropod community structure. Interestingly, we were also able to show an influence of the preceding crops, indicating an ecological memory effect in the aboveground arthropod community. Our results show that crop identity of both currently and previously grown crops in crop rotations may lead to an increase in arthropod activity density and changes in species composition. Diversified crop rotations including appropriate crops can be an easily implemented tool to increase arthropod biodiversity and biomass at large spatial and temporal scales, particularly in areas dominated by a single crop (e.g., wheat, maize). Our results may help to design optimized crop rotations for large-scale enhancement of insect biodiversity in agroecosystems.

8.
J Virol ; 93(21)2019 11 01.
Artículo en Inglés | MEDLINE | ID: mdl-31434738

RESUMEN

Adoptive cell transfer (ACT) is a powerful experimental approach to directly study T-cell-mediated immunity in vivo In the rhesus macaque AIDS virus model, infusing simian immunodeficiency virus (SIV)-infected animals with CD8 T cells engineered to express anti-SIV T-cell receptor specificities enables direct experimentation to better understand antiviral T-cell immunity in vivo Limiting factors in ACT experiments include suboptimal trafficking to, and poor persistence in, the secondary lymphoid tissues targeted by AIDS viruses. Previously, we redirected CD8 T cells to B-cell follicles by ectopic expression of the CXCR5 homing protein. Here, we modify peripheral blood mononuclear cell (PBMC)-derived CD8 T cells to express the CCR9 chemokine receptor, which induces preferential homing of the engineered cells to the small intestine, a site of intense early AIDS virus replication and pathology in rhesus macaques. Additionally, we increase in vivo persistence and overall systemic distribution of infused CD8 T cells, especially in secondary lymphoid tissues, by minimizing ex vivo culture/manipulation, thereby avoiding the loss of CD28+/CD95+ central memory T cells by differentiation in culture. These proof-of-principle results establish the feasibility of preferentially localizing PBMC-derived CD8 T cells to the small intestine and enables the direct experimental ACT-based assessment of the potential role of the quality and timing of effective antiviral CD8 T-cell responses to inhibit viral infection and subsequent replication in small intestine CD4 T cells. More broadly, these results support the engineered expression of homing proteins to direct CD8 T cells to target tissues as a means for both experimental and potential therapeutic advances in T-cell immunotherapies, including cancer.IMPORTANCEAdoptive cell transfer (ACT) of T cells engineered with antigen-specific effector properties can deliver targeted immune responses against malignancies and infectious diseases. Current T-cell-based therapeutic ACT relies on circulatory distribution to deliver engineered T cells to their targets, an approach which has proven effective for some leukemias but provided only limited efficacy against solid tumors. Here, engineered expression of the CCR9 homing receptor redirected CD8 T cells to the small intestine in rhesus macaque ACT experiments. Targeted homing of engineered T-cell immunotherapies holds promise to increase the effectiveness of adoptively transferred cells in both experimental and clinical settings.


Asunto(s)
Linfocitos T CD8-positivos/inmunología , Quimiotaxis de Leucocito/inmunología , Intestino Delgado/inmunología , Receptores CCR/metabolismo , Traslado Adoptivo , Animales , Antígenos CD28/metabolismo , Linfocitos T CD8-positivos/metabolismo , Quimiocinas CC/metabolismo , Memoria Inmunológica , Intestino Delgado/virología , Leucocitos Mononucleares/inmunología , Ganglios Linfáticos/inmunología , Macaca mulatta , Transducción de Señal , Síndrome de Inmunodeficiencia Adquirida del Simio/inmunología , Síndrome de Inmunodeficiencia Adquirida del Simio/virología , Virus de la Inmunodeficiencia de los Simios/inmunología
9.
Virology ; 535: 272-278, 2019 09.
Artículo en Inglés | MEDLINE | ID: mdl-31357166

RESUMEN

The late (L) domain sequence used by mouse mammary tumor virus (MMTV) remains undefined. Similar to other L domain-containing proteins, MMTV p8 and p14NC proteins are monoubiquitinated, suggesting L domain function. Site-directed mutagenesis of p8, PLPPV, and p14NC, PLPPL, sequences in MMTV Gag revealed a requirement only for the PLPPV sequence in virion release in a position-dependent manner. Electron microscopy of a defective Gag mutant confirmed an L domain budding defect morphology. The equine infectious anemia virus (EIAV) YPDL core L domain sequence and PLPPV provided L domain function in reciprocal MMTV and EIAV Gag exchange mutants, respectively. Alanine scanning of the PLPPV sequence revealed a strict requirement for the valine residue but only minor requirements for any one of the other residues. Thus, PLPPV provides MMTV L domain function, representing a fourth type of retroviral L domain that enables MMTV Gag proteins to co-opt cellular budding pathways for release.


Asunto(s)
Secuencias de Aminoácidos , Productos del Gen gag/metabolismo , Virus del Tumor Mamario del Ratón/crecimiento & desarrollo , Liberación del Virus , Animales , Productos del Gen gag/química , Productos del Gen gag/genética , Células HEK293 , Humanos , Virus del Tumor Mamario del Ratón/química , Virus del Tumor Mamario del Ratón/genética , Ratones , Microscopía Electrónica
10.
Nat Ecol Evol ; 3(6): 919-927, 2019 06.
Artículo en Inglés | MEDLINE | ID: mdl-31110252

RESUMEN

Predator-prey interactions in natural ecosystems generate complex food webs that have a simple universal body-size architecture where predators are systematically larger than their prey. Food-web theory shows that the highest predator-prey body-mass ratios found in natural food webs may be especially important because they create weak interactions with slow dynamics that stabilize communities against perturbations and maintain ecosystem functioning. Identifying these vital interactions in real communities typically requires arduous identification of interactions in complex food webs. Here, we overcome this obstacle by developing predator-trait models to predict average body-mass ratios based on a database comprising 290 food webs from freshwater, marine and terrestrial ecosystems across all continents. We analysed how species traits constrain body-size architecture by changing the slope of the predator-prey body-mass scaling. Across ecosystems, we found high body-mass ratios for predator groups with specific trait combinations including (1) small vertebrates and (2) large swimming or flying predators. Including the metabolic and movement types of predators increased the accuracy of predicting which species are engaged in high body-mass ratio interactions. We demonstrate that species traits explain striking patterns in the body-size architecture of natural food webs that underpin the stability and functioning of ecosystems, paving the way for community-level management of the most complex natural ecosystems.


Asunto(s)
Ecosistema , Cadena Alimentaria , Animales , Tamaño Corporal , Conducta Predatoria , Vertebrados
11.
J Am Chem Soc ; 141(20): 8327-8338, 2019 05 22.
Artículo en Inglés | MEDLINE | ID: mdl-31042030

RESUMEN

For HIV to become infectious, any new virion produced from an infected cell must undergo a maturation process that involves the assembly of viral polyproteins Gag and Gag-Pol at the membrane surface. The self-assembly of these viral proteins drives formation of a new viral particle as well as the activation of HIV protease, which is needed to cleave the polyproteins so that the final core structure of the virus will properly form. Molecules that interfere with HIV maturation will prevent any new virions from infecting additional cells. In this manuscript, we characterize the unique mechanism by which a mercaptobenzamide thioester small molecule (SAMT-247) interferes with HIV maturation via a series of selective acetylations at highly conserved cysteine and lysine residues in Gag and Gag-Pol polyproteins. The results provide the first insights into how acetylation can be utilized to perturb the process of HIV maturation and reveal a new strategy to limit the infectivity of HIV.


Asunto(s)
Fármacos Anti-VIH/farmacología , Benzamidas/farmacología , VIH/efectos de los fármacos , Desplegamiento Proteico/efectos de los fármacos , Ensamble de Virus/efectos de los fármacos , Productos del Gen gag del Virus de la Inmunodeficiencia Humana/efectos de los fármacos , Acetilación , Secuencia de Aminoácidos , Línea Celular , Cisteína/química , Proteínas de Fusión gag-pol/química , Proteínas de Fusión gag-pol/efectos de los fármacos , Humanos , Lisina/química , Productos del Gen gag del Virus de la Inmunodeficiencia Humana/química
12.
Ecol Evol ; 8(15): 7717-7732, 2018 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-30151184

RESUMEN

Imaging techniques are a cornerstone of contemporary biology. Over the last decades, advances in microscale imaging techniques have allowed fascinating new insights into cell and tissue morphology and internal anatomy of organisms across kingdoms. However, most studies so far provided snapshots of given reference taxa, describing organs and tissues under "idealized" conditions. Surprisingly, there is an almost complete lack of studies investigating how an organism's internal morphology changes in response to environmental drivers. Consequently, ecology as a scientific discipline has so far almost neglected the possibilities arising from modern microscale imaging techniques. Here, we provide an overview of recent developments of X-ray computed tomography as an affordable, simple method of high spatial resolution, allowing insights into three-dimensional anatomy both in vivo and ex vivo. We review ecological studies using this technique to investigate the three-dimensional internal structure of organisms. In addition, we provide practical comparisons between different preparation techniques for maximum contrast and tissue differentiation. In particular, we consider the novel modality of phase contrast by self-interference of the X-ray wave behind an object (i.e., phase contrast by free space propagation). Using the cricket Acheta domesticus (L.) as model organism, we found that the combination of FAE fixative and iodine staining provided the best results across different tissues. The drying technique also affected contrast and prevented artifacts in specific cases. Overall, we found that for the interests of ecological studies, X-ray computed tomography is useful when the tissue or structure of interest has sufficient contrast that allows for an automatic or semiautomatic segmentation. In particular, we show that reconstruction schemes which exploit phase contrast can yield enhanced image quality. Combined with suitable specimen preparation and automated analysis, X-ray CT can therefore become a promising quantitative 3D imaging technique to study organisms' responses to environmental drivers, in both ecology and evolution.

13.
Cardiol Ther ; 7(1): 107-117, 2018 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-29667131

RESUMEN

Right ventricular (RV) myxomas are extremely rare, but may have dreadful clinical sequelae including pulmonary embolism (PE). We present a case of a patient who had an RV myxoma that was attached to the tricuspid valve, and therefore could not be resected completely during surgery, and remnants of the tumor were seen on transthoracic echocardiogram during post-operative follow-up. Five months after surgery, the patient had PE, which could be due to tumor emboli or thromboemboli. Since repeat surgical resection was not feasible, the patient was started on warfarin. The patient is doing well and has had no PE recurrence over the past 20 months of follow-up. We have complemented the current case report with a comprehensive literature search and review on RV myxomas associated with PE in order to shed light on this uncommon but potentially lethal disorder. We concluded that right-sided cardiac myxomas, including RV myxomas, should be considered while dealing with PE, particularly in young patients with no risk factors, and that follow-up with echocardiography after surgery is important due to the possibility of recurrence, especially if complete resection was difficult to perform. Plain language summary available for this article.

14.
PLoS One ; 13(3): e0195246, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-29590210

RESUMEN

[This corrects the article DOI: 10.1371/journal.pone.0023703.].

15.
Semin Cardiothorac Vasc Anesth ; 21(4): 364-366, 2017 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-28709382

RESUMEN

Alkaptonuric ochronosis is a rare cause of aortic valve stenosis. We report the case of a 61-year-old female patient with alkaptonuria who presented to our institute with the clinical picture of severe aortic valve stenosis, which was confirmed by transthoracic echocardiography. On aortotomy, she was noted to have an impressive black discoloration of ascending aorta and the aortic root complex involving the aortic valve leaflets. She underwent an uneventful aortic valve replacement. She was discharged home 10 days postoperatively.


Asunto(s)
Alcaptonuria/complicaciones , Estenosis de la Válvula Aórtica/etiología , Estenosis de la Válvula Aórtica/cirugía , Válvula Aórtica/cirugía , Implantación de Prótesis de Válvulas Cardíacas/métodos , Ocronosis/complicaciones , Válvula Aórtica/diagnóstico por imagen , Estenosis de la Válvula Aórtica/diagnóstico por imagen , Ecocardiografía/métodos , Femenino , Humanos , Persona de Mediana Edad
16.
Am Nat ; 190(1): 131-143, 2017 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-28617641

RESUMEN

Living organisms are constrained by both resource quantity and quality. Ecological stoichiometry offers important insights into how the elemental composition of resources affects their consumers. If resource quality decreases, consumers can respond by shifting their body stoichiometry, avoiding low-quality resources, or up-regulating feeding rates to maintain the supply of required elements while excreting excess carbon (i.e., compensatory feeding). We analyzed multitrophic consumer body stoichiometry, biomass, and feeding rates along a resource-quality gradient in the litter of tropical forest and rubber and oil-palm plantations. Specifically, we calculated macroinvertebrate feeding rates based on consumer metabolic demand and assimilation efficiency. Using linear mixed effects models, we assessed resource-quality effects on macroinvertebrate detritivore and predator communities. We did not detect shifts in consumer body stoichiometry or decreases in consumer biomass in response to declining resource quality, as indicated by increasing carbon-to-nitrogen ratios. However, across trophic levels, we found a strong indication of decreasing resource quality leading to increased consumer feeding rates through altered assimilation efficiency and community body size structure. Our study reveals the influence of resource quality on multitrophic consumer feeding rates and suggests compensatory feeding to be more common across consumer trophic levels than was formerly known.


Asunto(s)
Invertebrados , Nitrógeno , Animales , Biomasa , Carbono , Ecología , Cadena Alimentaria
17.
J Anim Ecol ; 86(5): 1114-1123, 2017 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-28504834

RESUMEN

High biodiversity and biomass of soil communities are crucial for litter decomposition in terrestrial ecosystems such as tropical forests. However, the leaf litter that these communities consume is of particularly poor quality as indicated by elemental stoichiometry. The impact of resource quantity, quality and other habitat parameters on species richness and biomass of consumer communities is often studied in isolation, although much can be learned from simultaneously studying both community characteristics. Using a dataset of 780 macro-invertebrate consumer species across 32 sites in tropical lowland rain forest and agricultural systems on Sumatra, Indonesia, we investigated the effects of basal resource stoichiometry (C:X ratios of N, P, K, Ca, Mg, Na, S in local leaf litter), litter mass (basal resource quantity and habitat space), plant species richness (surrogate for litter habitat heterogeneity), and soil pH (acidity) on consumer species richness and biomass across different consumer groups (i.e. 3 feeding guilds and 10 selected taxonomic groups). In order to distinguish the most important predictors of consumer species richness and biomass, we applied a standardised model averaging approach investigating the effects of basal resource stoichiometry, litter mass, plant species richness and soil pH on both consumer community characteristics. This standardised approach enabled us to identify differences and similarities in the magnitude and importance of such effects on consumer species richness and biomass. Across consumer groups, we found litter mass to be the most important predictor of both species richness and biomass. Resource stoichiometry had a more pronounced impact on consumer species richness than on their biomass. As expected, taxonomic groups differed in which resource and habitat parameters (basal resource stoichiometry, litter mass, plant species richness and pH) were most important for modulating their community characteristics. The importance of litter mass for both species richness and biomass indicates that these tropical consumers strongly depend on habitat space and resource availability. Our study supports previous theoretical work indicating that consumer species richness is jointly influenced by resource availability and the balanced supply of multiple chemical elements in their resources.


Asunto(s)
Biodiversidad , Invertebrados , Suelo , Animales , Biomasa , Ecosistema , Bosques
18.
PLoS Pathog ; 13(5): e1006359, 2017 May.
Artículo en Inglés | MEDLINE | ID: mdl-28472156

RESUMEN

HIV and SIV infection dynamics are commonly investigated by measuring plasma viral loads. However, this total viral load value represents the sum of many individual infection events, which are difficult to independently track using conventional sequencing approaches. To overcome this challenge, we generated a genetically tagged virus stock (SIVmac239M) with a 34-base genetic barcode inserted between the vpx and vpr accessory genes of the infectious molecular clone SIVmac239. Next-generation sequencing of the virus stock identified at least 9,336 individual barcodes, or clonotypes, with an average genetic distance of 7 bases between any two barcodes. In vitro infection of rhesus CD4+ T cells and in vivo infection of rhesus macaques revealed levels of viral replication of SIVmac239M comparable to parental SIVmac239. After intravenous inoculation of 2.2x105 infectious units of SIVmac239M, an average of 1,247 barcodes were identified during acute infection in 26 infected rhesus macaques. Of the barcodes identified in the stock, at least 85.6% actively replicated in at least one animal, and on average each barcode was found in 5 monkeys. Four infected animals were treated with combination antiretroviral therapy (cART) for 82 days starting on day 6 post-infection (study 1). Plasma viremia was reduced from >106 to <15 vRNA copies/mL by the time treatment was interrupted. Virus rapidly rebounded following treatment interruption and between 87 and 136 distinct clonotypes were detected in plasma at peak rebound viremia. This study confirmed that SIVmac239M viremia could be successfully curtailed with cART, and that upon cART discontinuation, rebounding viral variants could be identified and quantified. An additional 6 animals infected with SIVmac239M were treated with cART beginning on day 4 post-infection for 305, 374, or 482 days (study 2). Upon treatment interruption, between 4 and 8 distinct viral clonotypes were detected in each animal at peak rebound viremia. The relative proportions of the rebounding viral clonotypes, spanning a range of 5 logs, were largely preserved over time for each animal. The viral growth rate during recrudescence and the relative abundance of each rebounding clonotype were used to estimate the average frequency of reactivation per animal. Using these parameters, reactivation frequencies were calculated and ranged from 0.33-0.70 events per day, likely representing reactivation from long-lived latently infected cells. The use of SIVmac239M therefore provides a powerful tool to investigate SIV latency and the frequency of viral reactivation after treatment interruption.


Asunto(s)
Variación Genética , Genoma Viral/genética , Modelos Teóricos , Síndrome de Inmunodeficiencia Adquirida del Simio/virología , Virus de la Inmunodeficiencia de los Simios/fisiología , Replicación Viral , Animales , Antirretrovirales/uso terapéutico , Linfocitos T CD4-Positivos/virología , Marcadores Genéticos/genética , Macaca mulatta , Masculino , Análisis de Secuencia de ADN , Síndrome de Inmunodeficiencia Adquirida del Simio/tratamiento farmacológico , Virus de la Inmunodeficiencia de los Simios/efectos de los fármacos , Virus de la Inmunodeficiencia de los Simios/genética , Carga Viral , Viremia
19.
Tex Heart Inst J ; 44(1): 77-79, 2017 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-28265220

RESUMEN

Celiac artery aneurysms are rare and typically warrant surgical treatment. Atherosclerosis is their chief cause. Symptomatic patients usually present with abdominal pain. Surgical resection of celiac artery aneurysms is associated with low morbidity and mortality rates. We report the case of a patient whose 2.2-cm celiac artery aneurysm we resected, with subsequent saphenous vein bypass grafting from the celiac trunk to the splenic and common hepatic arteries. In addition, we briefly discuss other treatment options.


Asunto(s)
Aneurisma/cirugía , Arteria Celíaca/cirugía , Arteria Hepática/cirugía , Vena Safena/trasplante , Arteria Esplénica/cirugía , Injerto Vascular/métodos , Anciano , Aneurisma/diagnóstico por imagen , Arteria Celíaca/diagnóstico por imagen , Angiografía por Tomografía Computarizada , Femenino , Arteria Hepática/diagnóstico por imagen , Humanos , Arteria Esplénica/diagnóstico por imagen , Resultado del Tratamiento
20.
J Virol ; 91(11)2017 06 01.
Artículo en Inglés | MEDLINE | ID: mdl-28298605

RESUMEN

Follicular helper CD4 T cells, TFH, residing in B-cell follicles within secondary lymphoid tissues, are readily infected by AIDS viruses and are a major source of persistent virus despite relative control of viral replication. This persistence is due at least in part to a relative exclusion of effective antiviral CD8 T cells from B-cell follicles. To determine whether CD8 T cells could be engineered to enter B-cell follicles, we genetically modified unselected CD8 T cells to express CXC chemokine receptor 5 (CXCR5), the chemokine receptor implicated in cellular entry into B-cell follicles. Engineered CD8 T cells expressing human CXCR5 (CD8hCXCR5) exhibited ligand-specific signaling and chemotaxis in vitro Six infected rhesus macaques were infused with differentially fluorescent dye-labeled autologous CD8hCXCR5 and untransduced CD8 T cells and necropsied 48 h later. Flow cytometry of both spleen and lymph node samples revealed higher frequencies of CD8hCXCR5 than untransduced cells, consistent with preferential trafficking to B-cell follicle-containing tissues. Confocal fluorescence microscopy of thin-sectioned lymphoid tissues demonstrated strong preferential localization of CD8hCXCR5 T cells within B-cell follicles with only rare cells in extrafollicular locations. CD8hCXCR5 T cells were present throughout the follicles with some observed near infected TFH In contrast, untransduced CD8 T cells were found in the extrafollicular T-cell zone. Our ability to direct localization of unselected CD8 T cells into B-cell follicles using CXCR5 expression provides a strategy to place highly effective virus-specific CD8 T cells into these AIDS virus sanctuaries and potentially suppress residual viral replication.IMPORTANCE AIDS virus persistence in individuals under effective drug therapy or those who spontaneously control viremia remains an obstacle to definitive treatment. Infected follicular helper CD4 T cells, TFH, present inside B-cell follicles represent a major source of this residual virus. While effective CD8 T-cell responses can control viral replication in conjunction with drug therapy or in rare cases spontaneously, most antiviral CD8 T cells do not enter B-cell follicles, and those that do fail to robustly control viral replication in the TFH population. Thus, these sites are a sanctuary and a reservoir for replicating AIDS viruses. Here, we demonstrate that engineering unselected CD8 T cells to express CXCR5, a chemokine receptor on TFH associated with B-cell follicle localization, redirects them into B-cell follicles. These proof of principle results open a pathway for directing engineered antiviral T cells into these viral sanctuaries to help eliminate this source of persistent virus.


Asunto(s)
Linfocitos B/fisiología , Linfocitos T CD8-positivos/metabolismo , Centro Germinal/inmunología , Infecciones por VIH/inmunología , Receptores CXCR5/genética , Receptores CXCR5/metabolismo , Animales , Linfocitos B/virología , Linfocitos T CD8-positivos/virología , Ingeniería Celular , Quimiotaxis , Centro Germinal/citología , Centro Germinal/virología , VIH-1/fisiología , Humanos , Macaca mulatta , Receptores CXCR5/inmunología , Receptores Mensajeros de Linfocitos/inmunología , Linfocitos T Colaboradores-Inductores/fisiología , Viremia , Replicación Viral/inmunología
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