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Natural selection is an important driver of genetic and phenotypic differentiation between species. For species in which potential gene flow is high but realized gene flow is low, adaptation via natural selection may be a particularly important force maintaining species. For a recent radiation of New World desert shrubs (Encelia: Asteraceae), we use fine-scale geographic sampling and population genomics to determine patterns of gene flow across two hybrid zones formed between two independent pairs of species with parapatric distributions. After finding evidence for extremely strong selection at both hybrid zones, we use a combination of field experiments, high-resolution imaging, and physiological measurements to determine the ecological basis for selection at one of the hybrid zones. Our results identify multiple ecological mechanisms of selection (drought, salinity, herbivory, and burial) that together are sufficient to maintain species boundaries despite high rates of hybridization. Given that multiple pairs of Encelia species hybridize at ecologically divergent parapatric boundaries, such mechanisms may maintain species boundaries throughout Encelia.
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Asteraceae/genética , Clima Desértico , Hibridación Genética , Selección Genética , Ecosistema , Flujo Génico , Aptitud Genética , Herbivoria , México , Salinidad , Agua , VientoRESUMEN
Neuron-microglia communication through the Cx3cr1-Cx3cl1 axis is essential for the development and refinement of neural circuits, which determine their function into adulthood. In the present work we set out to extend the behavioral characterization of Cx3cr1-/- mice evaluating innate behaviors and spatial navigation, both dependent on hippocampal function. Our results show that Cx3cr1-deficient mice, which show some changes in microglial and synaptic terminals morphology and density, exhibit alterations in activities of daily living and in the rapid encoding of novel spatial information that, nonetheless, improves with training. A neural substrate for these cognitive deficiencies was found in the form of synaptic dysfunction in the CA3 region of the hippocampus, with a marked impact on the mossy fiber (MF) pathway. A network analysis of the CA3 microcircuit reveals the effect of these synaptic alterations on the functional connectivity among CA3 neurons with diminished strength and topological reorganization in Cx3cr1-deficient mice. Neonatal population activity of the CA3 region in Cx3cr1-deficient mice shows a marked reorganization around the giant depolarizing potentials, the first form of network-driven activity of the hippocampus, suggesting that alterations found in adult subjects arise early on in postnatal development, a critical period of microglia-dependent neural circuit refinement. Our results show that interruption of the Cx3cr1-Cx3cl1/neuron-microglia axis leads to changes in CA3 configuration that affect innate and learned behaviors.
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Conducta Animal , Receptor 1 de Quimiocinas CX3C , Comunicación Celular , Quimiocina CX3CL1 , Microglía , Neuronas , Actividades Cotidianas , Animales , Conducta Animal/fisiología , Receptor 1 de Quimiocinas CX3C/genética , Receptor 1 de Quimiocinas CX3C/metabolismo , Comunicación Celular/genética , Comunicación Celular/fisiología , Quimiocina CX3CL1/genética , Quimiocina CX3CL1/metabolismo , Modelos Animales de Enfermedad , Hipocampo/metabolismo , Humanos , Ratones , Ratones Noqueados , Microglía/metabolismo , Neuronas/metabolismoRESUMEN
The Amazon basin holds the world's largest freshwater fish diversity. Information on the intensity and timing of reproductive ecology of Amazonian fish is scant. We use a metabarcoding method by capture using a single probe to quantify species-level ichthyoplankton dynamics. We sampled the Marañón and the Ucayali rivers in Peru monthly for 2 years. We identified 97 species that spawned mainly during the flood start, the flood end or the receding periods, although some species had spawning activity in more than one period. This information was new for 40 of the species in the Amazon basin and 80 species in Peru. Most species ceased spawning for a month during a strong hydrological anomaly in January 2016, demonstrating the rapidity with which they react to environmental modifications during the breeding season. We also document another unreported event in the Amazon basin, the inverse phenology of species belonging to one genus (Triportheus). Overall larval flow in the Marañón was more than twice that of the Ucayali, including for most commercial species (between two and 20 times higher), whereas the Ucayali accounts for ~80% of the fisheries landings in the region. Our results are discussed in the light of the main anthropogenic threats to fishes, hydropower dam construction and the Hidrovía Amazónica, and should serve as a pre-impact baseline.
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Peces , Ríos , Animales , Explotaciones Pesqueras , Larva , Estaciones del AñoRESUMEN
In pathogen recognition, the nucleotide-binding domain (NBD) and leucine rich repeat receptors (NLRs) have noteworthy functions in the activation of the innate immune response. These receptors respond to several viral infections, among them NOD2, a very dynamic NLR, whose role in dengue virus (DENV) infection remains unclear. This research aimed to determine the role of human NOD2 in THP-1 macrophage-like cells during DENV-2 infection. NOD2 levels in DENV-2 infected THP-1 macrophage-like cells was evaluated by RT-PCR and Western blot, and an increase was observed at both mRNA and protein levels. We observed using confocal microscopy and co-immunoprecipitation assays that NOD2 interacts with the effector protein MAVS (mitochondrial antiviral signaling protein), an adaptor protein promoting antiviral activity, this occurring mainly at 12 h into the infection. After silencing NOD2, we detected increased viral loads of DENV-2 and lower levels of IFN-α in supernatants from THP-1 macrophage-like cells with NOD2 knock-down and further infected with DENV-2, compared with mock-control or cells transfected with Scramble-siRNA. Thus, NOD2 is activated in response to DENV-2 in THP-1 macrophage-like cells and participates in IFN-α production, in addition to limiting virus replication at the examined time points.
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Prefrontal cortex (PFC)-related functions, such as working memory (WM) and cognitive flexibility (CF), are among the first to be altered at early stages of Alzheimer's disease (AD). Likewise, transgenic AD models carrying different AD-related mutations, mostly linked to the overproduction of amyloid beta (Aß) and other peptides, show premature behavioral and functional symptoms associated with PFC alterations. However, little is known about the effects of intracerebral or intra-PFC Aß infusion on WM and CF, as well as on pyramidal cell excitability and plasticity. Thus, here we evaluated the effects of a single Aß injection, directly into the PFC, or its intracerebroventricular (icv) application, on PFC-dependent behaviors and on the intrinsic and synaptic properties of layer V pyramidal neurons in PFC slices. We found that a single icv Aß infusion reduced learning and performance of a delayed non-matching-to-sample WM task and prevented reversal learning in a matching-to-sample version of the task, several weeks after its infusion. The inhibition of WM performance was reproduced more potently by a single PFC Aß infusion and was associated with Aß accumulation. This behavioral disruption was related to increased layer V pyramidal cell firing, larger sag membrane potential, increased fast after-hyperpolarization and a failure to sustain synaptic long-term potentiation, even leading to long-term depression, at both the hippocampal-PFC pathway and intracortical synapses. These findings show that Aß can affect PFC excitability and synaptic plasticity balance, damaging PFC-dependent functions, which could constitute the foundations of the early alterations in executive functions in AD patients.
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Enfermedad de Alzheimer , Péptidos beta-Amiloides , Animales , Potenciación a Largo Plazo , Masculino , Plasticidad Neuronal , Células Piramidales , Ratas , SinapsisRESUMEN
The landfall of Hurricane Harvey in August 2017 provided the opportunity to study the impact of extreme freshwater discharge on chromophoric dissolved organic matter (CDOM) properties in a subtropical estuary (Galveston Bay, Texas). Both fluorescence spectroscopy (excitation-emission matrices) and a three-component parallel factor analysis (PARAFAC) model identified changes in CDOM properties. Comparing to Coble's peaks, component 1 was similar to peak C, component 2 to peak M, and component 3 to peak B. Results clearly show three periods with distinct CDOM properties: a dry season, a wet season, and Hurricane Harvey. The dry season was characterized by higher values of the spectral slope and fluorescence and biological indices. The wet season was characterized by high values of PARAFAC components 1 and 2 (humic-like) and the absorption coefficient at 350 nm. Some CDOM components were highly correlated with salinity, indicating conservative mixing. Component 3 (protein-like) had a low correlation to salinity, suggesting degradation or production processes in the bay. Silicates and NO3- + NO2- had negative relationships with salinity and a positive one with PARAFAC components 1 and 2. PARAFAC component 3 was correlated with dissolved oxygen and chlorophyll a, suggesting a relationship between CDOM fluorescent components and phytoplankton activity. High values of the humification index were observed immediately after Hurricane Harvey, indicating increased input of terrestrial organic matter into the bay. Hurricane Harvey increased CDOM levels and humification, and the variability and changes seem to be mostly due to freshwater discharge from the San Jacinto River and not the Trinity River. The influx of freshwater was sufficient to eliminate the salinity gradient in Galveston Bay and significantly change CDOM properties. Galveston Bay recovered quickly from the hurricane and associated flux of freshwater, returning to pre-hurricane CDOM characteristics in less than 2 months.
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Tormentas Ciclónicas , Estuarios , Bahías , China , Clorofila A , Ríos , Espectrometría de FluorescenciaRESUMEN
Toluene is an organic solvent commonly misused by inhalation among adolescents to experience psychoactive effects. Repeated toluene exposure produces several cognitive deficits, including working memory impairment in which the medial prefrontal cortex (mPFC) plays a central role. Among other effects, toluene antagonizes NMDA receptors, enhance GABAA receptor-mediated responses and increases dopamine release. We have recently reported that animals repeatedly exposed to toluene show increased mPFC excitability; however, alterations in synaptic transmission, including long-term synaptic plasticity of glutamatergic responses have not been studied thus far. Here we used extracellular recordings to determine the effects of repeated toluene exposure (8000â¯ppm for 30â¯min, twice a day, for ten days) on the synaptic transmission converging on prelimbic layer 5 pyramidal neurons of the mPFC in adolescent male Wistar rats. Repeated toluene exposure increased mPFC's synaptic strength and reduced the inhibitory transmission assessed by input-output curves and paired-pulse inhibition protocols, respectively. Both toluene and a selective D1 receptor antagonist blocked the ability of exogenous dopamine to induce synaptic potentiation. Repeated toluene exposure also altered the ability of NMDA to induce synaptic depression of excitatory transmission. Taken together, the changes in synaptic strength and impairment of the NMDA-mediated plasticity of the mPFC demonstrate a series of synaptic modifications of the glutamatergic transmission that may underlie the cognitive impairment resulting from repeated toluene exposure.
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Corteza Prefrontal/efectos de los fármacos , Transmisión Sináptica/efectos de los fármacos , Tolueno/toxicidad , Animales , Dopamina/metabolismo , Ácido Glutámico/metabolismo , Ácido Quinurénico/farmacología , Masculino , N-Metilaspartato/metabolismo , Plasticidad Neuronal/efectos de los fármacos , Picrotoxina/farmacología , Racloprida/farmacología , Ratas , Ratas WistarRESUMEN
INTRODUCTION AND OBJECTIVE: There is not enough information about carbonated beverages (CB) consumption in Mexican women and its association with bone mineral density (BMD). The objective was to identify the association of CB consumption with BMD in two groups of Mexican women. METHODS: Transversal study with 328 women in reproductive age (WRA) and not reproductive (WNRA) with diet and anthropometric evaluation and BMD. RESULTS: Mean age of 18.7 years in WRA and 47 in WNRA. Energy adequacy percentage was lower in WNRA (98 ± 28% vs 144 ± 55) (p = 0.001), calcium intake was < 700 mg/day in women with osteopenia of both groups and median consumption of CB was higher in WRA, with 200 mL/day (0-462) vs 0 (0-250) in WNRA (p = 0.001), WRA with osteopenia drank 500 mL/day (253-750) of CB vs 100 (0-200) in who had not (p = 0.001). Anthropometric parameters were higher in WNRA (p =?0.002) and femoral neck BMD was lower (1.031 ± 0.14 vs 1.107 ± 0.10) (p = 0.001) and higher in L2-L4 (1.114 ± 0.13 vs 1.003 ± 0.09) (p = 0.001) in WRA. Variables associated with risk of osteopenia: drink CB (OR 11.186, p = 0.001), consuming < 700 mg of calcium (OR 5.774, p = 0.001) and dinner no milk (OR 1.942, p = 0.042). CONCLUSIONS: To drink CB increases risk of osteopenia in both groups, WRA drink more CB than WNRA and they will have high probability of fractures younger.
Introducción y objetivo: No hay información suficiente sobre el consumo de bebidas carbonatadas (BC) y su asociación con la densidad mineral ósea (DMO) en mexicanas. El objetivo fue identificar la asociación del consumo de BC con la DMO en dos grupos de mujeres mexicanas. Métodos: Estudio transversal con 328 mujeres en edad reproductiva (MER) y no reproductiva (MENR), con evaluación dietética, antropométrica y DMO. Resultados: Edad promedio de 18,7 años en MER y 47 años en MENR. El porcentaje de adecuación del consumo de energía fue inferior en MENR (98 ± 28% vs 144 ± 55) (p = 0,001), el consumo de calcio fue < 700 mg/día en mujeres con osteopenia de ambos grupos y la mediana del consumo de BC fue mayor en MER, con 200 mL/día (0- 462) vs 0 (0-250) en MENR (p = 0,001), las MER con osteo penia bebían 500 mL/día (253-750 mL/día) de BC/día vs 100 (0-200 mL/día) en las que no la presentaron (p = 0,001). Los parámetros antropométricos fueron superiores en MENR (p =?0.002) y la DMO en cuello de fémur fue inferior 1,031 ± 0,14 vs 1,107 ± 0,10 (p = 0,001), en MER fue mayor en L2-L4: 1,114 ± 0,13 vs 1,003 ± 0,09 (p = 0,001). Variables asociadas al riesgo de osteopenia: beber BC (OR 11,186; p = 0,001), consumir < 700 mg de calcio (OR 5,774; p = 0,001) y no cenar leche (OR 1,942; p = 0,042). Conclusiones: Beber BC aumenta el riesgo de osteopenia en ambos grupos, las MER consumen más BC que las MENR y tienen aún más probabilidad de fracturas a edades más tempranas.
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Densidad Ósea , Bebidas Gaseosas/estadística & datos numéricos , Adolescente , Adulto , Estudios Transversales , Descalcificación Patológica , Femenino , Humanos , México , Adulto JovenRESUMEN
Kainic acid induces seizures and neurotoxicity in rats, produces changes in brain serotonin (5-HT), dopamine and noradrenaline metabolites among other changes in neurotransmitters. In this work, we investigated the changes in 5-HT turnover in brain regions from 84 rats intraperitoneally injected with kainic acid and a specific behavioural change, the body and head shakes, exerted by this neurotoxin in the presence of 5-HT receptor antagonists. Kainic acid produced an increase in 5-hydroxyindoleacetic acid levels in frontal cortex (212%; 180%), striatum (177%; 116%), amygdala (202%; 337%) and hippocampus (43%; 70 %) at 2 and 24 hr as compared with controls, respectively. Serotonin turnover was increased in amygdala (157%) and frontal cortex (169%) at 2 hr; whereas 24 hr after kainic acid administration, increases were observed in amygdala (207%), and frontal cortex (178%). Kainic acid also produced an increase in the frequency of head and body shakes when administered alone or together with pargyline, a monoamine oxidase inhibitor; whereas the administration of 5-HT receptor antagonists such as ketanserin and methiothepin, decreased this behaviour 54% and 50% as compared with kainic acid alone, respectively. These results suggest an active participation of 5-HT neurotransmission on the excitotoxic action of kainic acid in the brain.
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Conducta Animal/efectos de los fármacos , Encéfalo/efectos de los fármacos , Agonistas de Aminoácidos Excitadores/toxicidad , Ácido Kaínico/toxicidad , Serotonina/metabolismo , Amígdala del Cerebelo/efectos de los fármacos , Amígdala del Cerebelo/metabolismo , Animales , Encéfalo/metabolismo , Corteza Cerebral/efectos de los fármacos , Corteza Cerebral/metabolismo , Cuerpo Estriado/efectos de los fármacos , Cuerpo Estriado/metabolismo , Agonistas de Aminoácidos Excitadores/metabolismo , Hipocampo/efectos de los fármacos , Hipocampo/metabolismo , Inyecciones Intraperitoneales , Ácido Kaínico/metabolismo , Ketanserina/farmacología , Masculino , Metiotepina/farmacología , Ratas , Ratas Wistar , Convulsiones/inducido químicamente , Convulsiones/metabolismo , Antagonistas de la Serotonina/farmacologíaRESUMEN
The susceptibility to penicillin of 111 Neisseria meningitidis strains was assessed by the agar-dilution procedure and serosubtypes were determined by a whole-cell enzyme-linked immunoassay using monoclonal antibodies reagents. Thirty-five isolates showed reduced sensitivity to penicillin (MIC > or = 0.1 mg/l and <= 1 mg/l) and no resistant strains were detected. The most common phenotype was B:4:P1.15 (77.5 percent) and a rising trend of non-typeable and non-subtypeable strains was detected. The increase in levels of minimal inhibitory concentrations of meningococci to penicillin gives cause for concern and the increase in non-typeable and non-subtypeable isolation demand the use of molecular biology techniques for their typing