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result(s) for
"Zuniga, Claudio"
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Does Nocturnality Drive Binocular Vision? Octodontine Rodents as a Case Study
by
Palacios, Adrián G.
,
Karten, Harvey J.
,
Medina, Felipe S.
in
Adaptation, Biological - physiology
,
Animal behavior
,
Animals
2013
Binocular vision is a visual property that allows fine discrimination of in-depth distance (stereopsis), as well as enhanced light and contrast sensitivity. In mammals enhanced binocular vision is structurally associated with a large degree of frontal binocular overlap, the presence of a corresponding retinal specialization containing a fovea or an area centralis, and well-developed ipsilateral retinal projections to the lateral thalamus (GLd). We compared these visual traits in two visually active species of the genus Octodon that exhibit contrasting visual habits: the diurnal Octodon degus, and the nocturnal Octodon lunatus. The O. lunatus visual field has a prominent 100° frontal binocular overlap, much larger than the 50° of overlap found in O. degus. Cells in the retinal ganglion cell layer were 40% fewer in O. lunatus (180,000) than in O. degus (300,000). O. lunatus has a poorly developed visual streak, but a well developed area centralis, located centrally near the optic disk (peak density of 4,352 cells/mm(2)). O. degus has a highly developed visual streak, and an area centralis located more temporally (peak density of 6,384 cells/mm(2)). The volumes of the contralateral GLd and superior colliculus (SC) are 15% larger in O. degus compared to O. lunatus. However, the ipsilateral projections to GLd and SC are 500% larger in O. lunatus than in O. degus. Other retinorecipient structures related to ocular movements and circadian activity showed no statistical differences between species. Our findings strongly suggest that nocturnal visual behavior leads to an enhancement of the structures associated with binocular vision, at least in the case of these rodents. Expansion of the binocular visual field in nocturnal species may have a beneficial effect in light and contrast sensitivity, but not necessarily in stereopsis. We discuss whether these conclusions can be extended to other mammalian and non-mammalian amniotes.
Journal Article
The Cuff Plus Anchoring Funnel Technique for Endovascular Aortic Repair (CAF-EVAR) for Large Infrarenal Necks
by
Andrés Reyes Valdivia
,
Zúñiga, Claudio Gandarias
,
Africa Duque Santos
in
Aneurysms
,
Aorta
,
Cardiovascular system
2018
PurposeTo present a case of a patient with possible short (2 years approximately) life expectancy and a 68-mm abdominal aortic aneurysm with a large infrarenal neck and large suprarenal aorta that precluded chimney endovascular aortic repair (Ch-EVAR) treatment.Materials and MethodsThe technical aspects of a modification of the funnel technique (thoracic endograft as a proximal extension of a main infrarenal device in wide necks) are described. We advocated a migrated bifurcated 36-mm endograft in a 34-mm native aorta, ten mm below the lowest renal artery and added endoanchor (four) fixation to this “intentionally migrated main endograft.” Afterward, we extended proximally a large aortic 38-mm-wide/50-mm-long cuff using the remaining 10-mm neck for cuff sealing. This aortic cuff achieved 8.5% oversizing in this 10-mm neck length. We again added additional endoanchoring (four) on this cuff.Results and ConclusionsInsights into technical issues for this bailout technique are described. No proximal endoleak or sac enlargement or migration is founded on 6-month follow up.
Journal Article
Bioeconomic effect from the size selection in red abalone intensive culture Haliotis rufescens as a production strategy
by
Pérez, Eduardo P.
,
Araneda, Marcelo
,
Araya, Andrea
in
bioeconomic models
,
Biomedical and Life Sciences
,
breeding
2012
The variability in growth is a common characteristic in mollusks breeding. Effects rising from the variability in the individual growth rate and the consequent dispersion of sizes in cultivation are important in financial terms. To manage this heterogeneity many firms use size selection, which can happen in two stages: toward the end of the stage of growing, or in the phase of growing of seeds. A bioeconomic model simulating the operation of a firm producing red abalone was implemented in spreadsheets. The firm produces 70 tons yearly. The model was structured in three sub-models. A biological sub-model detailed a batch’s dynamics, in terms of survival and growth, considering individual variation of size around a central value for each age. A technological sub-model described raw materials, the quantity of food and the energy required. Finally, the simulation model is completed with an economic integrated sub-model, where net present value is calculated considering income and costs over the time. Results of the alternative production strategies (with or without selection) are assessed according to: quantity of larvae and necessary spawners to reach the desired level of production; net present value (NPV) and necessary time to recover the investment. The number of larvae was approximately 17 millions larger for the case of the strategy of production with sizes selection and 73% more of available spawners is required for this larger amount of larvae. In the short term, the size-selection strategy increases the production costs at the initial time, compared with the strategy without selection. However, in the long term, this strategy generates greater NPV. The span for investment recovery was shorter for the case of the strategy with size selection and living product (nearly 2,140 days) than frozen (nearly 2,232 days); while without sizes selection a 15-year simulation showed the investment is not recovered. Finally, could be verified that size selection can be an interesting strategy to explore, since it improves the financial result, the same way other more expensive technological changes would.
Journal Article
Association between insulin resistance and the development of cardiovascular disease
2018
For many years, cardiovascular disease (CVD) has been the leading cause of death around the world. Often associated with CVD are comorbidities such as obesity, abnormal lipid profiles and insulin resistance. Insulin is a key hormone that functions as a regulator of cellular metabolism in many tissues in the human body. Insulin resistance is defined as a decrease in tissue response to insulin stimulation thus insulin resistance is characterized by defects in uptake and oxidation of glucose, a decrease in glycogen synthesis, and, to a lesser extent, the ability to suppress lipid oxidation. Literature widely suggests that free fatty acids are the predominant substrate used in the adult myocardium for ATP production, however, the cardiac metabolic network is highly flexible and can use other substrates, such as glucose, lactate or amino acids. During insulin resistance, several metabolic alterations induce the development of cardiovascular disease. For instance, insulin resistance can induce an imbalance in glucose metabolism that generates chronic hyperglycemia, which in turn triggers oxidative stress and causes an inflammatory response that leads to cell damage. Insulin resistance can also alter systemic lipid metabolism which then leads to the development of dyslipidemia and the well-known lipid triad: (1) high levels of plasma triglycerides, (2) low levels of high-density lipoprotein, and (3) the appearance of small dense low-density lipoproteins. This triad, along with endothelial dysfunction, which can also be induced by aberrant insulin signaling, contribute to atherosclerotic plaque formation. Regarding the systemic consequences associated with insulin resistance and the metabolic cardiac alterations, it can be concluded that insulin resistance in the myocardium generates damage by at least three different mechanisms: (1) signal transduction alteration, (2) impaired regulation of substrate metabolism, and (3) altered delivery of substrates to the myocardium. The aim of this review is to discuss the mechanisms associated with insulin resistance and the development of CVD. New therapies focused on decreasing insulin resistance may contribute to a decrease in both CVD and atherosclerotic plaque generation.
Journal Article
Characterization of physiological and antioxidant responses in Run1Ren1 Vitis vinifera plants during Erysiphe necator attack
by
INOSTROZA BLANCHETEAU, CLAUDIO ANDRES
,
Martinez Barradas, Vera
,
Arce Johnson, Patricio
in
Agricultural production
,
Airborne microorganisms
,
Antioxidants
2022
Grapevine is a fruit crop of major significance worldwide. Fungal attacks are one of the most relevant factors affecting grapevine yield and fruit quality, and powdery mildew caused by Erysiphe necator is one of the most harmful fungal diseases for this fruit-bearing species. Incorporating resistance genes such as Run1 and Ren1 in new vine selections offers a sustainable alternative to control the disease. These combined loci produce an immune response that prevents the development of the disease. However, to date studies are lacking concerning whether this response generates alterations in the physiological and antioxidant parameters of resistant plants in the presence of the fungus or if it has an associated energy cost. Therefore, the main goal of our research was to determine if Run1Ren1 plants present alterations in their physiological and biochemical parameters in the presence of the fungus. To achieve this target, a previously characterized resistant Run1Ren1 genotype and the susceptible Carmenere cultivar were analyzed. We evaluated photochemical parameters (Fv'/Fm', phi PSII and ETR), net photosynthesis (Pn), photosynthetic pigments, transpiration (E), stomatal conductance (g(s)), oxidative stress parameters (MDA), antioxidant activity, and phenols. Our results show that the physiological parameters of Run1Ren1 plants were not negatively affected by the fungus at 10 days post-inoculation, contrasting with alterations observed in the susceptible plants. Therefore, we propose that the resistance response triggered by Run1Ren1 is physiologically and biochemically advantageous to grapevines by preventing the development of powdery mildew infection.
Journal Article
Minicells as an Escherichia coli mechanism for the accumulation and disposal of fluorescent cadmium sulphide nanoparticles
by
Pérez-Donoso, José M.
,
Valenzuela-Ibaceta, Felipe
,
Ramos-Zúñiga, Javiera
in
Accumulation
,
Atomic absorption spectroscopy
,
Bacteria
2024
Background
Bacterial biosynthesis of fluorescent nanoparticles or quantum dots (QDs) has emerged as a unique mechanism for heavy metal tolerance. However, the physiological pathways governing the removal of QDs from bacterial cells remains elusive. This study investigates the role of minicells, previously identified as a means of eliminating damaged proteins and enhancing bacterial resistance to stress. Building on our prior work, which unveiled the formation of minicells during cadmium QDs biosynthesis in
Escherichia coli
, we hypothesize that minicells serve as a mechanism for the accumulation and detoxification of QDs in bacterial cells.
Results
Intracellular biosynthesis of CdS QDs was performed in
E. coli
mutants Δ
minC
and Δ
minCDE
, known for their minicell-producing capabilities. Fluorescence microscopy analysis demonstrated that the generated minicells exhibited fluorescence emission, indicative of QD loading. Transmission electron microscopy (TEM) confirmed the presence of nanoparticles in minicells, while energy dispersive spectroscopy (EDS) revealed the coexistence of cadmium and sulfur. Cadmium quantification through flame atomic absorption spectrometry (FAAS) demonstrated that minicells accumulated a higher cadmium content compared to rod cells. Moreover, fluorescence intensity analysis suggested that minicells accumulated a greater quantity of fluorescent nanoparticles, underscoring their efficacy in QD removal. Biosynthesis dynamics in minicell-producing strains indicated that biosynthesized QDs maintained high fluorescence intensity even during prolonged biosynthesis times, suggesting continuous QD clearance in minicells.
Conclusions
These findings support a model wherein
E. coli
utilizes minicells for the accumulation and removal of nanoparticles, highlighting their physiological role in eliminating harmful elements and maintaining cellular fitness. Additionally, this biosynthesis system presents an opportunity for generating minicell-coated nanoparticles with enhanced biocompatibility for diverse applications.
Graphical Abstract
Journal Article
TASK-3 Downregulation Triggers Cellular Senescence and Growth Inhibition in Breast Cancer Cell Lines
2018
TASK-3 potassium channels are believed to promote proliferation and survival of cancer cells, in part, by augmenting their resistance to both hypoxia and serum deprivation. While overexpression of TASK-3 is frequently observed in cancers, the understanding of its role and regulation during tumorigenesis remains incomplete. Here, we evaluated the effect of reducing the expression of TASK-3 in MDA-MB-231 and MCF-10F human mammary epithelial cell lines through small hairpin RNA (shRNA)-mediated knockdown. Our results show that knocking down TASK-3 in fully transformed MDA-MB-231 cells reduces proliferation, which was accompanied by an induction of cellular senescence and cell cycle arrest, with an upregulation of cyclin-dependent kinase (CDK) inhibitors p21 and p27. In non-tumorigenic MCF-10F cells, however, TASK-3 downregulation did not lead to senescence induction, although cell proliferation was impaired and an upregulation of CDK inhibitors was also evident. Our observations implicate TASK-3 as a critical factor in cell cycle progression and corroborate its potential as a therapeutic target in breast cancer treatment.
Journal Article
Copper-induced concomitant increases in photosynthesis, respiration, and C, N and S assimilation revealed by transcriptomic analyses in Ulva compressa (Chlorophyta)
by
Sáez, Claudio A.
,
Moenne, Alejandra
,
Laporte, Daniel
in
Agriculture
,
Algae
,
Algal Proteins - analysis
2020
Background
The marine alga
Ulva compressa
is the dominant species in copper-polluted coastal areas in northern Chile. It has been shown that the alga tolerates micromolar concentrations of copper and accumulates copper at the intracellular level. Transcriptomic analyses were performed using total RNA of the alga cultivated with 10 μ M copper for 0, 1, 3 and 5 days using RNA-seq in order to identify processes involved in copper tolerance.
Results
The levels of transcripts encoding proteins belonging to Light Harvesting Complex II (LHCII), photosystem II (PSII), cytochrome b6f, PSI, LHCI, ATP synthase and proteins involved in repair of PSII and protection of PSI were increased in the alga cultivated with copper. In addition, the level of transcripts encoding proteins of mitochondrial electron transport chain, ATP synthase, and enzymes involved in C, N and S assimilation were also enhanced. The higher percentages of increase in the level of transcripts were mainly observed at days 3 and 5. In contrast, transcripts involved protein synthesis and degradation, signal transduction, and replication and DNA repair, were decreased. In addition, net photosynthesis and respiration increased in the alga cultivated with copper, mainly at days 1 to 3. Furthermore, the activities of enzymes involved in C, N and S assimilation, rubisco, glutamine synthase and cysteine synthase, respectively, were also increased, mainly at days 1 and 3.
Conclusions
The marine alga
U. compressa
tolerates copper excess through a concomitant increase in expression of proteins involved in photosynthesis, respiration, and C, N and S assimilation, which represents an exceptional mechanism of copper tolerance.
Journal Article
Copper stress induces antioxidant responses and accumulation of sugars and phytochelatins in Antarctic Colobanthus quitensis (Kunth) Bartl
by
Zúñiga, Gustavo E.
,
Sáez, Claudio A.
,
Contreras, Rodrigo A.
in
Abiotic stress
,
Amino acids
,
Antarctica
2018
Background
In field,
C. quitensis
is subjected to many abiotic extreme environmental conditions, such as low temperatures, high UV-B, salinity and reduced water potentials, but not metal or metalloid high concentrations in soil, however, other members of Caryophyllaceae family have tolerance to high concentrations of metals, this is the case of
Silene
genre. In this work, we hypothesize that
C. quitensis
have the same mechanisms of
Silene
to tolerate metals, involving accumulation and induction of antioxidant systems, sugar accumulation and the induction of thiols such as phytochelatins to tolerate.
Results
The results showing an effective antioxidant defensive machinery involving non-enzymatic antioxidants such as phenolics, GSH and ascorbic acid, in another hand, GSH-related oligomers (phytochelatins) and sugars was induced as a defensive mechanism.
Conclusions
Colobanthus quitensis
exhibits certain mechanisms to tolerate copper in vitro demonstrating its plasticity to tolerate several abiotic stress conditions.
Journal Article