En esta investigación se plantea y analiza un modelo matemático mediante un sistema de ecuaciones diferenciales ordinarias no lineales que representa la bioecología de los mosquitos Aedes aegypti, por cuanto involucra su ciclo de vida y sus sitios reproductivos principales. Se hallan las soluciones constantes del sistema en términos del umbral de crecimiento poblacional, haciéndose el análisis de estabilidad a cada una. Se realiza un análisis de sensibilidad local del umbral de crecimiento y del equilibrio de coexistencia en términos de los parámetros demográficos contemplados en la dinámica. Con datos calculados e hipotéticos, se presentan resultados numéricos de las soluciones del sistema, los cuales se obtienen con ayuda del software matemático Maple.
34Monodelphis domestica, also known as the laboratory opossum, is a marsupial native to South 35 America. At birth, these animals are developmentally equivalent to human embryos at 36 approximately 5 weeks of gestation which, when coupled with other characteristics including the 37 size of the animals, the development of a robust immune system during juvenile development, 38 and the relative ease of experimental manipulation, have made M. domestica a valuable model in 39 many areas of biomedical research. However, their suitability as models for infectious diseases, 40 especially diseases caused by viruses such as Zika virus (ZIKV), is currently unknown. Here, we 41 describe the replicative effects of ZIKV using a fetal intra-cerebral model of inoculation. Using 42 immunohistochemistry and in situ hybridization, we found that opossum embryos and fetuses are 43 susceptible to infection by ZIKV administered intra-cerebrally, that the infection persists long 44 term, and that the infection and viral replication consistently results in neural pathology and may 45 occasionally result in global growth restriction. These results demonstrate the utility of M. 46 domestica as a new animal model for investigating ZIKV infection in vivo. This new model will 47facilitate further inquiry into viral pathogenesis, particularly for those viruses that are 48 neurotropic, that may require a host with the ability to support sustained viral infection, and/or 49 that may require intra-cerebral inoculations of large numbers of embryos or fetuses. 50 AUTHOR SUMMARY 51Here we show that the laboratory opossum (Monodelphis domestica) is a valuable new model for 52 studying Zika virus pathogenesis. Newborns are at the developmental stage of 5-week human 53 embryos. Zika virus inoculated on a single occasion into the brains of pups at the human 54 developmental stages of 8-20 weeks post conception replicated in neuronal cells and persisted as 55 a chronic infection until the experimental endpoint at 74-days post infection. In addition, we 3 56 observed global growth restriction in one of 16 inoculated animals; global growth restriction has 57 been observed in humans and other animal models infected with Zika virus. The results illustrate 58 great potential for this new animal model for high throughput research on the neurological 59 effects of Zika virus infection of embryos and fetuses. 60 INTRODUCTION 61 Zika virus (ZIKV) is a small, enveloped positive-sense RNA virus from the family 62 Flaviviridae. Typically transmitted in a zoonotic cycle that alternates between a vertebrate host 63 and an invertebrate vector, ZIKV gained notoriety following the 2015 outbreak in Brazil, which 64 saw a dramatic increase in the number of neurological abnormalities in infants born to ZIKV-65 infected mothers [1]. Significant increases in Guillain-Barre syndrome and microcephaly during 66 this outbreak were also observed when compared to previous years [2], perhaps fulfilling the 67 theory posited by Hayes when he declared ZIKV to be neurovirulent [3...
El objetivo en esta investigación es motivar una reflexión crítica frente a la práctica de la modelación matemática en el país a partir de una experiencia pedagógica. Las personas participantes eran estudiantes y la docente en el nivel quinto de educación básica de un colegio colombiano. Para el estudio se adoptó un enfoque cualitativo y la información que se recolectó mediante entrevistas, observaciones y documentos escritos por las estudiantes, fue analizada por el practicante docente para evidenciar fortalezas y dificultades. Los resultados dan evidencia de que la modelación matemática usada integralmente, despierta en el estudiantado un mayor interés, gusto y mejor desempeño en el área de matemáticas. Se concluye que la calidad de los procesos de enseñanza y aprendizaje exige que docentes y directivos docentes promuevan espacios de investigación, análisis e indagación a través de material concreto y situaciones contextualizadas. Para ello se recomienda la aplicación de herramientas tecnológicas en el ámbito escolar utilizadas como medio facilitador de las actividades de modelación matemática, mayor capacitación, disponibilidad de recursos y apoyo institucional para la adecuada planificación del personal docente.
Living organisms have been exposed to light-dark cycles that allowed them to adapt to different ecological niches. Circadian cycles affect hormone release, metabolism, and response to xenobiotic compounds. Current studies have shown that insect susceptibility to toxic agents depends on circadian cycles, mainly because the biochemical processes involved in detoxification and responses to oxidative stress are modulated by this process. The goal of this study was to determine the effect of photoperiod on resistance to permethrin in Aedes aegypti . Collections of Ae. aegypti from 4 locations in Yucatan, southern Mexico, were subjected to 2 different photoperiod schemes: dark (0 h light:24 h dark) and natural photoperiod (12 h light:12 h dark). The comparison of both photoperiods was evaluated with respect to permethrin resistance using bottle bioassays and by monitoring the possible mechanism related such as enzymatic activity and by the frequency of 2 knockdown resistance mutations in the voltage-dependent sodium channel gene (V1016I and F1534C). The susceptible strain was used as a reference. The mosquitoes in dark photoperiod showed a reduction in resistance to the pyrethroid. The α-esterases and glutathione S-transferase enzymatic activities showed lower levels in the dark photoperiod, and the frequencies of V1016I knockdown resistance mutation showed significant difference between photoperiod schemes.
A mathematical model for dengue fever transmission is analyzed, which incorporates relevant biological and ecological factors: vertical transmission and seasonality in the interaction between the vector (Aedes aegypti females) and the host (human). The existence and uniqueness of a positive disease-free periodic solution is proved; the global stability of the disease-free solution and the effect of periodic migrations of mosquitoes carrying the virus on the transmission of dengue are analyzed utilizing the mathematical definition of the Basic Reproductive Number in periodic environments; finally, it is numerically corroborated with the help of the Basic Reproductive Number that dengue cannot invade the disease-free state if it is less than one and can invade if it is greater than one, however, in both threshold conditions when vertical transmission occurs, the number of infected people and carrier vectors rises, representing a mechanism for the persistence of dengue cases in a community throughout a natural year.
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