Browsing by Author "Bozinovic, Francisco"

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    Andrographolide Reduces Neuroinflammation and Oxidative Stress in Aged Octodon degus
    (SPRINGER, 2020) Lindsay, Carolina B.; Zolezzi, Juan M.; Rivera, Daniela S.; Cisternas, Pedro; Bozinovic, Francisco; Inestrosa, Nibaldo C.
    Alzheimer's disease (AD) is a devastating neurodegenerative disorder in which superior brain functions, such as memory and cognition, are impaired. Currently, no effective treatment is available for AD. Although andrographolide (ANDRO), a compound extracted from the herb Andrographis paniculata, has shown interesting effects in models of several diseases, including AD, its effects on other molecular changes observed in AD, such as neuroinflammation and oxidative stress, have not yet been studied. To evaluate the impact of ANDRO-based intervention on the levels of amyloid-beta (A beta) and neuroinflammatory and oxidative stress markers in the brains of aged Octodon degus, a Chilean rodent, fifty-six-month-old O. degus were treated intraperitoneally with 2 or 4 mg/kg ANDRO. Vehicle-injected and 12-month-old O. degus were used as positive controls. Then, the protein levels of selected markers were assessed via immunohistochemistry and immunoblotting. ANDRO significantly reduced the total A beta burden as well as astrogliosis and interleukin-6 levels. Moreover, ANDRO significantly reduced the levels of 4-hydroxynonenal and N-tyrosine adducts, suggesting a relevant reduction in oxidative stress within aged O. degus brain. Considering that O. degus has been proposed as a potential "natural" model for sporadic AD due to the development of neuropathological markers that resemble this pathology, our results suggest that ANDRO should be further studied to establish its potential as a therapeutic drug for AD.
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    Flight initiation distance is differentially sensitive to the costs of staying and leaving food patches in a small-mammal prey
    (CANADIAN SCIENCE PUBLISHING, 2009) Lagos, Patricio A.; Meier, Andrea; Ortiz Tolhuysen, Liliana; Castro, Rodrigo A.; Bozinovic, Francisco; Ebensperger, Luis A.
    Escape theory predicts that a prey should flee from an approaching predator at a point in which the cost of staying equals the cost of escape. We manipulated the cost of fleeing upon approaching human predators by providing the small mammal Octodon degus (Molina, 1782) with varying amounts of supplementary food likely to disappear while the animals are not in the food patch (e.g., hidden in their burrows). Simultaneously, we manipulated the risk of remaining in the patch by providing supplementary food at varying distances from the nearest burrow. Degus fled at a shorter distance to approaching predators when foraging in patches closer to the nearest burrow and supplied with relatively high abundance of food, but only when these rodents were foraging socially. Also, degus fled at a greater distance to approaching predators when foraging in patches far from the nearest burrow. Thus, functions linked to the loss of feeding opportunities and the risk of predation interact to influence flight initiation distance after a simulated attack. This study represented one of the few demonstrations of an interactive effect between cost and risks on antipredator behavior in a small, social prey mammal.
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    Phenotypic variability in byssus thread production of intertidal mussels induced by predators with different feeding strategies
    (INTER-RESEARCH, 2008) Caro, Andres U.; Escobar, Joan; Bozinovic, Francisco; Navarrete, Sergio A.; Castilla, Juan Carlos
    Predator-induced defenses have a significant influence on the expression of morphological and behavioral traits of marine species. In mussels, common responses to predators include thickening of the shell, enlargement of the adductor muscle and increases in byssus production. We hypothesize that predators with different feeding strategies have different effects on byssus production of the common intertidal mussels Perumytilus purpuratus and Semimytilus algosus in central Chile, Predators that dislodge prey mussels before killing them, such as crabs and seastars, should elicit increased byssus production in their prey compared to other predators such as whelks, which use different feeding mechanisms. Laboratory experiments with the seastar Heliaster helianthus, the crab Acanthocylus gayi, and the muricid gastropods Concholepas concholepas and Acanthina monodon showed that: only A. gayi induced significant increases in byssus production, causing remarkably similar responses in both mussel species. Further experiments in which individual mussels with different: attachment strengths were offered to A. gayi showed that the crabs first tried different mussels and then selected those with the weakest attachment, leading to consumption rates of weakly attached mussels that were 5 to 6 times higher than those of mussels with strong attachment to the substratum. Measurements of mussel attachment: strengths in the field showed that, where A. gayi is abundant, both mussel species are more strongly attached than in habitats where this predator is scarce. While responses of mussels to crabs seem to be adaptive, the lack of a response to H. helianthus is intriguing, because it is one of the most important. mussel predators in the system which can dislodge entire Clumps Of Mussels at a time. It is possible that increased byssus production is ineffective in reducing predation by this large predator; however, this adaptive explanation requires further studies. These results highlight the predator-specific nature of many prey phenotypic responses and the importance of considering the multiplicity of predators typically present in most habitats.
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    Phylogeography of the subterranean rodent Spalacopus cyanus (Caviomorpha, Octodontidae)
    (ALLIANCE COMMUNICATIONS GROUP DIVISION ALLEN PRESS, 2008) Opazo, Juan C.; Bugueno, Manuel P.; Carter, Mauricio J.; Palma, R. Eduardo; Bozinovic, Francisco
    Spalacopus cyanus is a subterranean rodent inhabiting coastal and mountain habitats. Individuals from mountain populations are larger than individuals from the coast, and mountain populations have a more limited geographic range. To investigate the genetic structure and biogeography of this species, we analyzed mitochondrial DNA control region sequences. We found low levels of nucleotide diversity in comparison with other subterranean rodents. Coastal populations had higher nucleotide diversity and effective population size than mountain populations. Phylogenetic analysis using maximum parsimony and a haplotype network generated using statistical parsimony recognized 3 groups of haplotypes: northern coastal and mountain populations, central coastal populations, and southern coastal population. Consistent with the presence of unshared haplotypes, migration rates were practically 0, except from Valparaiso to Ventanas and from La Parva to Huentelauquen. We observed asymmetric migration rates from mountain to coastal populations, suggesting that this species originated in the Andean mountains. A likelihood ration test could not reject the null hypothesis of a stable population when all sequences were grouped into a single population and when coastal populations were analyzed separately. However, a negative exponential growth parameter was estimated for mountain populations,suggesting that these populations have undergone recent demographic changes.
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    The effect of diet quality on physiological and life-history traits in the harvestman Pachylus paesslerik
    (PERGAMON-ELSEVIER SCIENCE LTD, 2007) Naya, Daniel E.; Lardies, Marco A.; Bozinovic, Francisco
    The balance between energy acquisition and expenditure is critical to the survival and reproductive success of animals. Here we investigate the long-term effects of diet quality on physiological and life-history flexibility in the harvestman, Pachylus paessleri. We used cow meal as a protein-rich diet and potatoes as a carbohydrate-rich diet in order to reproduce two extreme conditions regarding food quality in harvestmen natural habitat. As proxy variables of the energy expenditure process, we quantified standard metabolic rate (maintenance), changes in body mass (somatic condition), and fecundity (reproduction). We found that animals consuming the protein-rich diet were able to increase both their body condition and fecundity. However, the increment in these two life-history traits was correlated with higher maintenance costs. In contrast, the carbohydrate-rich diet did not provide enough specific nutrients for reproductive events, although it may have allowed animals to survive for a long time. Thus, according to the quality of the diet available in the environment, harvestman females can adopt different life-history strategies correlated with phenotypic adjustments at anatomical and physiological levels. In the Mediterranean region, spatial and temporal changes in food quality are typical, so greater phenotypic flexibility is expected to cope with this kind of environmental variation. (c) 2006 Elsevier Ltd. All rights reserved.
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    The Mean and Variance of Environmental Temperature Interact to Determine Physiological Tolerance and Fitness
    (UNIV CHICAGO PRESS, 2011) Bozinovic, Francisco; Bastias, Daniel A.; Boher, Francisca; Clavijo Baquet, Sabrina; Estay, Sergio A.; Angilletta, Michael J., Jr.
    Global climate change poses one of the greatest threats to biodiversity. Most analyses of the potential biological impacts have focused on changes in mean temperature, but changes in thermal variance will also impact organisms and populations. We assessed the combined effects of the mean and variance of temperature on thermal tolerances, organismal survival, and population growth in Drosophila melanogaster. Because the performance of ectotherms relates nonlinearly to temperature, we predicted that responses to thermal variation (+/-0 degrees or +/-5 degrees C) would depend on the mean temperature (17 degrees or 24 degrees C). Consistent with our prediction, thermal variation enhanced the rate of population growth (r(max)) at a low mean temperature but depressed this rate at a high mean temperature. The interactive effect on fitness occurred despite the fact that flies improved their heat and cold tolerances through acclimation to thermal conditions. Flies exposed to a high mean and a high variance of temperature recovered from heat coma faster and survived heat exposure better than did flies that developed at other conditions. Relatively high survival following heat exposure was associated with low survival following cold exposure. Recovery from chill coma was affected primarily by the mean temperature; flies acclimated to a low mean temperature recovered much faster than did flies acclimated to a high mean temperature. To develop more realistic predictions about the biological impacts of climate change, one must consider the interactions between the mean environmental temperature and the variance of environmental temperature.