Nicolás Gálvez

Relationship between fragmentation, degradation and native and exotic species richness in an Andean temperate forest of Chile

Impactos humanos tales como la fragmentacion y degradacion de bosques pueden tener fuertes efectos en las comunidades de especies vegetales nativas y exoticas. Ademas, perturbaciones antropicas ocurren principalmente en menores altitudes produciendo mayores grados de fragmentacion y degradacion que en mayores altitudes. La invasion de plantas exoticas deberia ser mayor en bosques mas fragmentados o degradados y, por lo tanto, en menores altitudes dentro de un tipo de bosque o piso altitudinal. En cambio, la riqueza de especies nativas deberia ser negativamente afectada por la fragmentacion y degradacion, encontrandose mayor riqueza en mayores altitudes dentro de un tipo de bosque determinado. En este trabajo evaluamos estas hipotesis en un bosque templado andino de la Region de la Araucania, Chile. Registramos la composicion de plantas vasculares en doce fragmentos de diferente tamano, razon perimetro/area, altitud y degradacion antropica (cortas, incendios, fecas de ganado). En base a estas variables construimos un indice de fragmentacion y uno de degradacion para estos fragmentos. Se analizaron las relaciones entre estas variables a traves de correlaciones de Pearson. Nuestros resultados sugieren que la fragmentacion y degradacion estan positivamente relacionadas y que ambos tipos de perturbacion ocurren en altitudes mas bajas del tipo de bosque estudiado. Ademas, la fragmentacion y degradacion estan afectando en diferente forma a la riqueza de especies nativas y exoticas. La invasion se incremento como consecuencia tanto de fragmentacion como de degradacion, y como consecuencia del patron de distribucion altitudinal de estas perturbaciones, la invasion aparentemente ocurre principalmente en zonas bajas. En cambio, la riqueza de especies nativas fue negativamente afectada solo por la fragmentacion, y no se relaciono con la degradacion interna de los bosques ni con la altitud.

Rufous-legged Owl (Strix rufipes) and Austral Pygmy Owl (Glaucidium nanum) stand use in a gradient of disrupted and old growth Andean temperate forests, Chile

We studied how human induced structural changes in forests affect stand use of the Rufous-legged Owl (forest-specialist) and the Austral Pygmy Owl (forest-facultative), in a gradient from lowland disrupted forests to protected Andean forests in Chile. We also tested if the calls of one species influenced the calling behaviour of the other. We detected a total of 34 Rufous-legged Owls and 21 Austral Pygmy Owls during the four seasons. Rufous-legged Owls were found principally in old growth Araucaria-Nothofagus stands (32.4%), and Pygmy Owls in old growth evergreen stands (52.4%). For both species there was a seasonal effect on call response, with a drop in responses in autumn and winter. Our models suggested that Rufous-legged Owls inhabit a more specific range of habitat characteristics than Pygmy Owls. The former selected stands with tall trees, relatively low tree density, and high bamboo density. Pygmy Owls selected stands with tall trees and relatively high tree density. There was no evidence that either species influenced the calling behaviour of the other, suggesting no negative association between use of a territory by the two species. Our results emphasize the importance of structural components of old growth forests for both species, but also the relevance of stands surrounding protected areas. Estudiamos cómo los cambios estructurales en el bosque, inducidos por el ser humano, afectan el uso de hábitat del concón (especialista de bosque) y del chuncho (facultativo de bosque), en un gradiente desde bosques perturbados en zonas bajas hasta bosques andinos protegidos de Chile. También evaluamos si los llamados de una especie influencian el comportamiento de vocalización de la otra. Detectamos un total de 34 concones y 21 chunchos para las cuatro estaciones del año. Los concones fueron registrados principalmente en bosques antiguos de Araucaria-Nothofagus (32.4%), y los chunchos en bosques antiguos siempre-verdes (52.4%). Para ambas especies hubo una disminución de la actividad en otoño e invierno. Nuestros modelos sugirieron que el concón tiene requerimientos de hábitat más específicos que el chuncho. El concón seleccionó bosques con árboles altos y en baja densidad relativa, y una alta densidad de quila. Por su parte, el chuncho seleccionó bosques con árboles altos y en alta densidad relativa. No hubo evidencia de que los llamados de una especie afectaran las respuestas de la otra, sugiriendo que no existe una asociación negativa en el uso de un mismo territorio por ellas. Los resultados enfatizan la importancia de los elementos estructurales de los bosques antiguos para ambas especies pero, a su vez, la relevancia de los bosques periféricos a áreas protegidas.

New insights on the viral and host factors contributing to the airway pathogenesis caused by the respiratory syncytial virus

Abstract The respiratory syncytial virus (RSV) is the most prevalent etiological agent of lower respiratory tract infections and the first cause of hospitalization in infants due to respiratory disease worldwide. However, efforts to develop safe and effective vaccines and antivirals have been challenged by an incomplete understanding of the RSV pathogenesis and the host immune response to RSV infection in the airways. Here, we discuss recent advances in understanding the interaction between RSV and the epithelium to induce pathogenesis in the airways, such as the role of the RSV NS2 protein in the airway epithelium, as well as the events involved in the RSV entry process. In addition, we summarize the cellular factors produced by airway epithelial cells (AECs) in response to RSV infection that lead to the activation of innate and adaptive immune responses, inducing lung inflammation and disease. Further, we discuss the possible contribution of a recently identified cytokine, thymic stromal lymphopoitein (TSLP), in the lung immunopathology caused by RSV.

A safe and efficient BCG vectored vaccine to prevent the disease caused by the human Respiratory Syncytial Virus

Abstract The human Respiratory Syncytial Virus (hRSV) causes lower respiratory tract infections including pneumonia and bronchiolitis. Such infections also cause a large number of hospitalizations and affects mainly newborns, young children and the elderly worldwide. Symptoms associated with hRSV infection are due to an exacerbated immune response characterized by low levels of IFN-γ, recruitment of neutrophils and eosinophils to the site of infection and lung damage. Although hRSV is a major health problem, no vaccines are currently available. Different immunization approaches have been developed to achieve a vaccine that activates the immune system, without triggering an unbalanced inflammation. These approaches include live attenuated vaccine, DNA or proteins technologies, and the use of vectors to express proteins of the virus. In this review, we discuss the host immune response to hRSV and the immunological mechanisms underlying an effective and safe BCG vectored vaccine against hRSV.

Activity patterns by two colour morphs of the vulnerable guiña, Leopardus guigna (Molina 1782), in temperate forests of southern Chile

Entregamos el primer analisis de patrones de actividad exhibidos por morfos moteados y melanicos de la vulnerable guina Leopardus guigna, en un paisaje de bosque del sur de Chile. Camaras trampas mostraron que las guinas estuvieron mayoritariamente activas en la noche (64% de fotos). Las guinas melanicas fueron mas nocturnas (82% de fotos) que las moteadas mas comunes (57%). Las guinas moteadas estuvieron mas activas en noches nubosas y oscuras. Nuestro estudio provee nuevos resultados sobre la plasticidad conductual de la guina en diferentes condiciones ambientales, y la ventaja relativa de cada morfo para persistir en un paisaje cada vez mas dominado por el ser humano.

Human Metapneumovirus: Mechanisms and Molecular Targets Used by the Virus to Avoid the Immune System

Human metapneumovirus (hMPV) is a respiratory virus, first reported the year 2001. Since then, it has been described as one of the main etiological agents that causes acute lower respiratory tract infections (ALRTIs), which is characterized by symptoms such as bronchiolitis, wheezing and coughing. Susceptible population to hMPV-infection includes newborn, children, elderly and immunocompromised individuals. This viral agent is a negative-sense, single-stranded RNA enveloped virus, that belongs to the Pneumoviridae family and Metapneumovirus genus. Early reports—previous to 2001—state several cases of respiratory illness without clear identification of the responsible pathogen, which could be related to hMPV. Despite the similarities of hMPV with several other viruses, such as the human respiratory syncytial virus or influenza virus, mechanisms used by hMPV to avoid the host immune system are still unclear. In fact, evidence indicates that hMPV induces a poor innate immune response, thereby affecting the adaptive immunity. Among these mechanisms, is the promotion of an anergic state in T cells, instead of an effective polarization or activation, which could be induced by low levels of cytokine secretion. Further, the evidences support the notion that hMPV interferes with several pattern recognition receptors (PRRs) and cell signaling pathways triggered by interferon-associated genes. However, these mechanisms reported in hMPV are not like the ones reported for hRSV, as the latter has two non-structural proteins that are able to inhibit these pathways. Several reports suggest that viral glycoproteins, such as G and SH, could play immune-modulator roles during infection. In this work, we discuss the state of the art regarding the mechanisms that underlie the poor immunity elicited by hMPV. Importantly, these mechanisms will be compared with those elicited by other common respiratory viruses.

Neurologic Alterations Due to Respiratory Virus Infections

Central Nervous System (CNS) infections are one of the most critical problems in public health, as frequently patients exhibit neurologic sequelae. Usually, CNS pathologies are caused by known neurotropic viruses such as measles virus (MV), herpes virus and human immunodeficiency virus (HIV), among others. However, nowadays respiratory viruses have placed themselves as relevant agents responsible for CNS pathologies. Among these neuropathological viruses are the human respiratory syncytial virus (hRSV), the influenza virus (IV), the coronavirus (CoV) and the human metapneumovirus (hMPV). These viral agents are leading causes of acute respiratory infections every year affecting mainly children under 5 years old and also the elderly. Up to date, several reports have described the association between respiratory viral infections with neurological symptoms. The most frequent clinical manifestations described in these patients are febrile or afebrile seizures, status epilepticus, encephalopathies and encephalitis. All these viruses have been found in cerebrospinal fluid (CSF), which suggests that all these pathogens, once in the lungs, can spread throughout the body and eventually reach the CNS. The current knowledge about the mechanisms and routes used by these neuro-invasive viruses remains scarce. In this review article, we describe the most recent findings associated to neurologic complications, along with data about the possible invasion routes of these viruses in humans and their various effects on the CNS, as studied in animal models.

New Insights Contributing to the Development of Effective Vaccines and Therapies to Reduce the Pathology Caused by hRSV

Human Respiratory Syncytial Virus (hRSV) is one of the major causes of acute lower respiratory tract infections (ALRTI) worldwide, leading to significant levels of immunocompromisation as well as morbidity and mortality in infants. Its main target of infection is the ciliated epithelium of the lungs and the host immune responses elicited is ineffective at achieving viral clearance. It is thought that the lack of effective immunity against hRSV is due in part to the activity of several viral proteins that modulate the host immune response, enhancing a Th2-like pro-inflammatory state, with the secretion of cytokines that promote the infiltration of immune cells to the lungs, with consequent damage. Furthermore, the adaptive immunity triggered by hRSV infection is characterized by weak cytotoxic T cell responses and secretion of low affinity antibodies by B cells. These features of hRSV infection have meant that, to date, no effective and safe vaccines have been licensed. In this article, we will review in detail the information regarding hRSV characteristics, pathology, and host immune response, along with several prophylactic treatments and vaccine prototypes. We will also expose significant data regarding the newly developed BCG-based vaccine that promotes protective cellular and humoral response against hRSV infection, which is currently undergoing clinical evaluation.

Seasonal dynamics of avian guilds inside and outside core protected areas in an Andean Biosphere Reserve of southern Chile

ABSTRACT Capsule: Many protected forests at high elevations show higher endemic biodiversity than unprotected habitats at low elevations. In seasonal ecosystems, however, harsh environmental conditions during winter may force individuals to move from protected forests to unprotected degraded forests in lowlands. Aims: To examine how forest types and seasons affect avian diversity and habitat-use guilds in protected and unprotected forests. Methods: Habitat and seasonal avian surveys were conducted to test forest type and seasonal differences on avian species richness, relative abundances and relative abundance of habitat-use guilds. Results: Twenty-three avian species (∼40% endemics) were recorded. Highland old growth forests showed the highest richness (4.1–4.9 species/point count). The lowest richness was recorded in mid-elevation secondary forests (3.1 species/point count). The highest relative abundances for habitat-specialist understorey users and large tree users were recorded in highland old growth forests. However, the abundance of large tree users was higher in secondary forests at low elevations during colder seasons. Conclusions: Some species and guilds may move to lower elevations outside protected areas during winter. Increasing degradation of unprotected areas will likely affect the suitability of ‘winter habitat’ for specialist guilds, and thus the ecological processes and source/sink dynamics occurring across boundaries of protected and unprotected areas.