Browsing by Author "Bozinovic, Francisco"

Now showing 1 - 6 of 6
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    A Multivariate Assessment of Age-Related Cognitive Impairment in Octodon degus
    (2021) Rivera, Daniela S.; Lindsay, Carolina B.; Oliva, Carolina A.; Bozinovic, Francisco; Inestrosa, Nibaldo C.
    Aging is a progressive functional decline characterized by a gradual deterioration in physiological function and behavior. The most important age-related change in cognitive function is decline in cognitive performance (i.e., the processing or transformation of information to make decisions that includes speed of processing, working memory, and learning). The purpose of this study is to outline the changes in age-related cognitive performance (i.e., short-term recognition memory and long-term learning and memory) in long-lived Octodon degus. The strong similarity between degus and humans in social, metabolic, biochemical, and cognitive aspects makes it a unique animal model for exploring the mechanisms underlying the behavioral and cognitive deficits related to natural aging. In this study, we examined young adult female degus (12- and 24-months-old) and aged female degus (38-, 56-, and 75-months-old) that were exposed to a battery of cognitive-behavioral tests. Multivariate analyses of data from the Social Interaction test or Novel Object/Local Recognition (to measure short-term recognition memory), and the Barnes maze test (to measure long-term learning and memory) revealed a consistent pattern. Young animals formed a separate group of aged degus for both short- and long-term memories. The association between the first component of the principal component analysis (PCA) from short-term memory with the first component of the PCA from long-term memory showed a significant negative correlation. This suggests age-dependent differences in both memories, with the aged degus having higher values of long-term memory ability but poor short-term recognition memory, whereas in the young degus an opposite pattern was found. Approximately 5% of the young and 80% of the aged degus showed an impaired short-term recognition memory; whereas for long-term memory about 32% of the young degus and 57% of the aged degus showed decreased performance on the Barnes maze test. Throughout this study, we outlined age-dependent cognitive performance decline during natural aging in degus. Moreover, we also demonstrated that the use of a multivariate approach let us explore and visualize complex behavioral variables, and identified specific behavioral patterns that allowed us to make powerful conclusions that will facilitate further the study on the biology of aging. In addition, this study could help predict the onset of the aging process based on behavioral performance.
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    Increasing importance of heat stress for cattle farming under future global climate scenarios
    (2021) Carvajal, Mario A.; Alaniz, Alberto J.; Gutierrez-Gomez, Constanza; Vergara, Pablo M.; Sejian, Veerasamy; Bozinovic, Francisco
    In the last decades, livestock species have been severely affected by heat stress because of increasing temperatures, which has threatened animal welfare and decreased production. Based on thermal comfort indices and ensemble climate projections, we analyzed the current and future global spatiotemporal patterns of the heat exposure of cattle in 10 agroclimatic zones. The results show that similar to 7% of the global cattle population is currently exposed to dangerous heat conditions. This percentage is projected to increase to similar to 48% before 2100 under a scenario of growing emissions. Tropical agroclimatic zones are expected to face an early increase in the exposure to intense heat before 2050. Heat exposure was negatively correlated with the socioeconomic variables, showing that poor and livestock-dependent tropical countries are the most affected. Our results demonstrate the near future consequences of heat stress on livestock, emphasizing the limited time available to implement effective abatement strategies. (C) 2021 Elsevier B.V. All rights reserved.
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    Rapid turnover of a pea aphid superclone mediated by thermal endurance in central Chile
    (2024) Martel, Sebastian I.; Zamora, Cristian A.; Ricote, Natalia; Sepulveda, Daniela A.; Maheo, Frederique; Simon, Jean-Christophe; Figueroa, Christian C.; Rezende, Enrico L.; Bozinovic, Francisco
    Global change drivers are imposing novel conditions on Earth's ecosystems at an unprecedented rate. Among them, biological invasions and climate change are of critical concern. It is generally thought that strictly asexual populations will be more susceptible to rapid environmental alterations due to their lack of genetic variability and, thus, of adaptive responses. In this study, we evaluated the persistence of a widely distributed asexual lineage of the alfalfa race of the pea aphid, Acyrthosiphon pisum, along a latitudinal transect of approximately 600 km in central Chile after facing environmental change for a decade. Based on microsatellite markers, we found an almost total replacement of the original aphid superclone by a new variant. Considering the unprecedented warming that this region has experienced in recent years, we experimentally evaluated the reproductive performance of these two A. pisum lineages at different thermal regimes. The new variant exhibits higher rates of population increase at warmer temperatures, and computer simulations employing a representative temperature dataset suggest that it might competitively displace the original superclone. These results support the idea of a superclone turnover mediated by differential reproductive performance under changing temperatures.
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    Spatial and seasonal plasticity in digestive morphology of cavies (Microcavia australis) inhabiting habitats with different plant qualities
    (2007) Sassi, Paola L.; Borghi, Carlos E.; Bozinovic, Francisco
    Ecological physiology examines how animals cope with changing environmental demands. In low-productivity desert habitats, small mammals should consume low-quality, high-fiber food as a consequence of necessity rather than by choice. Diet quality of populations can differ at both spatial and temporal scales. Nevertheless, spatial and temporal variation in the digestive system has not been extensively studied in the field. We captured individuals from 4 populations of Microcavia australis and measured their digestive morphological traits. Fieldwork was carried out in 4 localities belonging to and and semiarid regions, in dry and wet seasons. We also estimated diet quality for each population and season. We found significant effects of sex, season, and site on the size of digestive organs. The concentration of fiber and nitrogen in the plants consumed differed between populations and varied seasonally: dietary fiber was higher in the dry season and nitrogen concentration was higher in the wet season. As predicted by theory, the cecum, the organ most closely related to cellulose fermentation, was significantly larger in animals facing the lowest quality diet. The other organs also were affected by reproductive state and water requirements. Intraspecific variation in the digestive morphology of M. australis probably helps this species cope with remarkable seasonal and geographical variability.
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    Spectral sensitivities of photoreceptors and their role in colour discrimination in the green-backed firecrown hummingbird (Sephanoides sephaniodes)
    (2008) Herrera, Gonzalo; Zagal, Juan Cristobal; Diaz, Marcelo; Fernandez, Maria Jose; Vielma, Alex; Cure, Michel; Martinez, Jaime; Bozinovic, Francisco; Palacios, Adrian G.
    We studied the photopic spectral sensitivity in the green-backed firecrown, Sephanoides sephaniodes, a South American hummingbird, and its possible ecological relationship with preferred flowers and body colouration. Avian colour vision is in general tetrachromatic with at least four types of cones, which vary in sensitivity from the near ultraviolet (UV) to the red wavelength range. Hummingbirds represent an important family of birds, yet little is known about their eye sensitivity, especially about the role of photoreceptors and their oil droplet complements. The photopic electroretinogram shows a main sensitivity peak at 560 nm and a secondary peak in the UV, and may be explained by the presence of four single cones (lambda(max) at similar to 370, 440, 508 and 560 nm), and a double cone (lambda(max) at 560 nm) screened by oil droplets. The flowers preferred by the firecrown are those in which the red-green wavelength region predominates and have higher contrast than other flowers. The crown plumage of males is highly iridescent in the red wavelength range (peak at 650 nm) and UV; when plotted in a high-dimensional tetrachromatic space, it falls in a "red + UV" purple hue line, suggesting a potential significant communication signal for sexual differentiation.
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    Thermal tolerance in Drosophila : Repercussions for distribution, community coexistence and responses to climate change
    (2022) Alruiz, José M. ; Peralta‐Maraver, Ignacio ; Bozinovic, Francisco ; Santos, Mauro ; Enrico L. Rezende
    Here we combined controlled experiments and field surveys to determine if estimates of heat tolerance predict distributional ranges and phenology of different Drosophila species in southern South America. We contrasted thermal death time curves, which consider both magnitude and duration of the challenge to estimate heat tolerance, against the thermal range where populations are viable based on field surveys in an 8-year longitudinal study. We observed a strong correspondence of the physiological limits, the thermal niche for population growth, and the geographic ranges across studied species, which suggests that the thermal biology of different species provides a common currency to understand how species will respond to warming temperatures both at a local level and throughout their distribution range. Our approach represents a novel analytical toolbox to anticipate how natural communities of ectothermic organisms will respond to global warming.