ABSTRACT
The dinoflagellate Alexandrium catenella is a well-known paralytic shellfish toxin producer that forms harmful algal blooms, repeatedly causing damage to Chilean coastal waters. The causes and behavior of algal blooms are complex and vary across different regions. As bacterial interactions with algal species are increasingly recognized as a key factor driving algal blooms, the present study identifies several bacterial candidates potentially associated with Chilean Alexandrium catenella. This research narrowed down the selection of bacteria from the Chilean A. catenella culture using antibiotic treatment and 16S rRNA metabarcoding analysis. Subsequently, seawater from two Chilean coastal stations, Isla Julia and Isla San Pedro, was monitored for two years to detect Alexandrium species and the selected bacteria, utilizing 16S and 18S rRNA gene metabarcoding analyses. The results suggested a potential association between Alexandrium species and Spongiibacteraceae at both stations. The proposed candidate bacteria within the Spongiibacteraceae family, potentially engaging in mutualistic relationships with Alexandrium species, included the genus of BD1-7 clade, Spongiibbacter, and Zhongshania.
Subject(s)
Dinoflagellida , RNA, Ribosomal, 16S , Symbiosis , Dinoflagellida/genetics , Dinoflagellida/physiology , Chile , RNA, Ribosomal, 16S/genetics , Bacteria/genetics , Bacteria/classification , Harmful Algal Bloom , Seawater/microbiology , Phylogeny , RNA, Ribosomal, 18S/geneticsABSTRACT
The Reloncaví estuary in southern Chile is famous for its aquaculture. However, recurring harmful algal blooms have adversely affected mussel production. Therefore, regular monitoring of algal toxins is urgently needed to better understand the contamination status of the estuary. In this study, we quantified 15 types of lipophilic shellfish toxins in Metri Bay in the Reloncaví estuary on a biweekly basis for 4 years. We identified algal species using microscopy and metabarcoding analysis. We also measured water temperature, salinity, chlorophyll-a, and dissolved oxygen to determine the potential relationships of these parameters with algal toxin production. Our results revealed the presence of a trace amount of pectenotoxin and the causal phytoplankton Dinophysis, as well as yessotoxin and the causal phytoplankton Protoceratium. Statistical analysis indicated that fluctuations in water temperature affected the detection of these toxins. Additionally, metabarcoding analysis detected the highly toxic phytoplankton Alexandrium spp. in some samples. Although our results suggest that the level of lipophilic shellfish toxins in Metri Bay during the study period was insignificantly low using our current LC-MS method, the confirmed presence of highly toxic algae in Metri Bay raises concerns, given that favorable environmental conditions could cause blooms.
Subject(s)
Environmental Monitoring , Estuaries , Harmful Algal Bloom , Marine Toxins , Phytoplankton , Chile , Marine Toxins/analysis , Animals , DinoflagellidaABSTRACT
Odorant receptors (ORs) are key specialized units for mate and host finding in moths of the Ditrysia clade, to which 98% of the lepidopteran species belong. Moth ORs have evolved to respond to long unsaturated acetates, alcohols, or aldehydes (Type I sex pheromones), falling into conserved clades of pheromone receptors (PRs). These PRs might have evolved from old lineages of non-Ditrysian moths that use plant volatile-like pheromones. However, a Ditrysian moth called the greater wax moth, Galleria mellonella (a worldwide-distributed pest of beehives), uses C9-C11 saturated aldehydes as the main sex pheromone components (i.e., nonanal and undecanal). Thus, these aldehydes represent unusual components compared with the majority of moth species that use, for instance, Type I sex pheromones. Current evidence shows a lack of consensus in the amount of ORs for G. mellonella, although consistent in that the moth does not have conserved PRs. Using genomic data, 62 OR candidates were identified, 16 being new genes. Phylogeny showed no presence of ORs in conserved PR clades. However, an OR with the highest transcript abundance, GmelOR4, appeared in a conserved plant volatile-detecting clade. Functional findings from the HEK system showed the OR as sensitive to nonanal and 2-phenylacetaldehyde, but not to undecanal. It is believed that to date GmelOR4 represents the first, but likely not unique, OR with a stable function in detecting aldehydes that help maintain the life cycle of G. mellonella around honey bee colonies.
Subject(s)
Moths , Receptors, Odorant , Sex Attractants , Animals , Bees/genetics , Moths/genetics , Sex Attractants/genetics , Aldehydes , Receptors, Pheromone/genetics , Receptors, Odorant/geneticsABSTRACT
In order to improve the water solubility and, therefore, bioavailability and therapeutic activity of anticancer hydrophobic drug α-tocopherol succinate (α-TOS), in this work, copolymers were synthesized via free radicals from QMES (1-[4,7-dichloroquinolin-2-ylmethyl]-4-methacryloyloxyethyl succinate) and VP (N-vinyl-2-pirrolidone) using different molar ratios, and were used to nanoencapsulate and deliver α-TOS into cancer cells MCF-7. QMES monomer was chosen because the QMES pendant group in the polymer tends to hydrolyze to form free 4,7-dichloro-2-quinolinemethanol (QOH), which also, like α-TOS, exhibit anti-proliferative effects on cancerous cells. From the QMES-VP 30:70 (QMES-30) and 40:60 (QMES-40) copolymers obtained, it was possible to prepare aqueous suspensions of empty nanoparticles (NPs) loaded with α-TOS by nanoprecipitation. The diameter and encapsulation efficiency (%EE) of the QMES-30 NPs loaded with α-TOS were 128.6 nm and 52%; while for the QMES-40 NPs loaded with α-TOS, they were 148.8 nm and 65%. The results of the AlamarBlue assay at 72 h of treatment show that empty QMES-30 NPs (without α-TOS) produced a marked cytotoxic effect on MCF-7 breast cancer cells, corresponding to an IC50 value of 0.043 mg mL-1, and importantly, they did not exhibit cytotoxicity against healthy HUVEC cells. Furthermore, NP-QMES-40 loaded with α-TOS were cytotoxic with an IC50 value of 0.076 mg mL-1, demonstrating a progressive release of α-TOS; however, the latter nanoparticles were also cytotoxic to healthy cells in the range of the assayed concentrations. These results contribute to the search for a new polymeric nanocarrier of QOH, α-TOS or other hydrophobic drugs for the treatment of cancer or others diseases treatable with these drugs.
ABSTRACT
Surface-modified PAMAM dendrimers have important applications in drug delivery, yet a gap remains about the role that surface functionalization plays on their cell internalization capacity. We examined the cell internalization kinetics of PAMAM dendrimers that were surface-modified with acetyl, folate and poly(ethylene glycol), as model functional groups differing in size, charge, and chemical functionality. Dendrimers with 25% functionalization were internalized by HEK cells, but with slower rates and lower maximum uptakes than the native dendrimer between 1-6 h of incubation. Dendrimers with 50% functionalization exhibited negligible internalization capacities at all incubation times. Molecular dynamics simulations revealed that the solvent accessibility of the cationic surface charges is a key factor affecting cell internalization, unlike the total charge, functionality or size of surface-modified PAMAM dendrimers. These findings provide valuable insights to assist the design of PAMAM-based systems for drug delivery applications.
Subject(s)
Dendrimers , Dendrimers/chemistry , Drug Delivery Systems , Polyethylene Glycols/chemistry , SolventsABSTRACT
Harmful Algal Blooms (HABs) have caused damage to the marine environment in Isla San Pedro in the Gulf of Corcovado, Chile. While rising water temperature and artificial eutrophication are the most discussed topics as a cause, marine bacteria is a recent attractive parameter as an algal bloom driver. This study monitored algal and bacterial compositions in the water of Isla San Pedro for one year using microscopy and 16S rRNA metabarcoding analysis, along with physicochemical parameters. The collected data were analyzed with various statistical tools to understand how the particle-associated bacteria (PA) and the free-living (FL) bacteria were possibly involved in algal blooms. Both FL and PA fractions maintained a stable bacterial composition: the FL fraction was dominated by Proteobacteria (α-Proteobacteria and γ-Proteobacteria), and Cyanobacteria dominated the PA fraction. The two fractions contained equivalent bacterial taxonomic richness (c.a. 8,000 Operational Taxonomic Units) and shared more than 50% of OTU; however, roughly 20% was exclusive to each fraction. The four most abundant algal genera in the Isla San Pedro water were Thalassiosira, Skeletonema, Chaetoceros, and Pseudo-nitzchia. Statistical analysis identified that the bacterial species Polycyclovorans algicola was correlated with Pseudo-nitzschia spp., and our monitoring data recorded a sudden increase of particle-associated Polycyclovorans algicola shortly after the increase of Pseudo-nitzschia, suggesting that P. algicola may have regression effect on Pseudo-nitzschia spp. The study also investigated the physicochemical parameter effect on algal-bacterial interactions. Oxygen concentration and chlorophyll-a showed a strong correlation with both FL and PA bacteria despite their assemblage differences, suggesting that the two groups had different mechanisms for interacting with algal species.
ABSTRACT
Harmful algal blooms, in particular recurrent blooms of the dinoflagellate Alexandrium catenella, associated with paralytic shellfish poisoning (PSP), frequently limit commercial shellfish harvests, resulting in serious socio-economic consequences. Although the PSP-inducing species that threaten the most vulnerable commercial species of shellfish are very patchy and spatially heterogeneous in their distribution, the spatial and temporal scales of their effects have largely been ignored in monitoring programs and by researchers. In this study, we examined the spatial and temporal dynamics of PSP toxicity in the clam (Ameghinomya antiqua) in two fishing grounds in southern Chile (Ovalada Island and Low Bay). During the summer of 2009, both were affected by an intense toxic bloom of A. catenella (up to 1.1 × 106 cells L-1). Generalized linear models were used to assess the potential influence of different environmental variables on the field detoxification rates of PSP toxins over a period of 12 months. This was achieved using a four parameter exponential decay model to fit and compare field detoxification rates per sampling site. The results show differences in the spatial variability and temporal dynamics of PSP toxicity, given that greater toxicities (+10-fold) and faster detoxification (20% faster) are observed at the Ovalada Island site, the less oceanic zone, and where higher amounts of clam are annually produced. Our observations support the relevance of considering different spatial and temporal scales to obtain more accurate assessments of PSP accumulation and detoxification dynamics and to improve the efficacy of fisheries management after toxic events.
Subject(s)
Dinoflagellida , Shellfish Poisoning , Toxins, Biological , Humans , Shellfish , Harmful Algal BloomABSTRACT
Introducción: la hipoacusia neonatal (HN) constituye un problema de salud relevante por su alta frecuencia de presentación y los efectos que esta puede tener en el desarrollo mental y psicológico del paciente. El tamizaje auditivo neonatal (TAN) es fundamental para la identificación de pacientes en riesgo de HN. Objetivo: caracterización de los pacientes con resultados anormales en las pruebas de TAN en el Hospital Universitario Clínica San Rafael. Diseño: estudio observacional descriptivo de corte transversal. Materiales y métodos: se identificaron características biológicas y clínicas en pacientes con emisiones otoacústicas o potenciales evocados auditivos anormales realizados entre 2018 y 2020. Los pacientes incluidos se dividieron en 2 grupos, según la presencia de los factores de riesgo para HN. Resultados: 9027 pacientes se tamizaron, 223 (24,7 %) tuvieron resultados anormales y 19 pacientes se excluyeron. En total, 204 pacientes se incluyeron, de los cuales 46 (22,5 %) fueron de alto riesgo (AR) y 158 (77,5 %) de bajo riesgo (BR). El TAN en pacientes BR se realizó antes del primer mes de vida en 78,5 % de los casos y en 21,4 % de los AR. Las características más frecuentes fueron la ventilación mecánica (45,6 %), la hospitalización en cuidados intensivos (43,5 %), la anormalidad craneofacial (15,2 %) y la hiperbilirrubinemia mayor de 20 mg/dL (10,8 %). Conclusiones: se deben optimizar los esfuerzos y recursos para realizar las pruebas de tamizaje auditivo antes del primer mes de vida al 100% de pacientes. Se deben realizar estudios complementarios para identificar los diagnósticos auditivos finales de los pacientes con resultados anormales, así como el tipo de tratamiento y la rehabilitación auditiva recibida.
Introduction: Neonatal hearing loss (NHL) is a relevant health problem due to its high incidence and the effects it may have both on the mental and psychological development of the patient. Neonatal hearing screening (NHS) is essential for the identification of patients at risk of NHL. Objective: To identify the characteristics of patients with abnormal NHS test results at the Hospital Universitario Clínica San Rafael. Design: Cross-sectional descriptive observational study. Materials and methods: Biological and clinical characteristics were identified in patients with abnormal otoacoustic emissions and/or auditory evoked potentials (AEP) performed between 2018 and 2020. Patients involved were divided into 2 groups according to the presence of risk factors for NHL. Results: 9027 patients were screened, 223 (24.7%) had abnormal results, but 19 patients were excluded. 204 patients were included in total, 46 (22.5%) of which were high risk (HR) and 158 (77.5%) were low risk (LR). NHS in LR patients was performed before the first month of life on 78.5% of cases and 21.4% of HR patients. The most frequent characteristics were mechanical ventilation (45.6%), intensive care unit admission (43.5%), craniofacial abnormality (15.2%) and hyperbilirubinemia greater than 20 mg/dL (10.8%). Conclusion: Efforts and resources should be optimized as means to perform hearing screening tests before the first month of life on 100% of patients. Complementary studies should be performed with the aim to identify the final auditory diagnoses of patients with abnormal results, as well as the type of treatment and auditory rehabilitation offered.
Subject(s)
Humans , Hearing Loss , Neonatal Screening , Evoked Potentials, AuditoryABSTRACT
Harmful algae blooms (HABs) monitoring has been implemented worldwide, and Chile, a country famous for its fisheries and aquaculture, has intensively used microscopic and toxin analyses for decades for this purpose. Molecular biological methods, such as high-throughput DNA sequencing and bacterial assemblage-based approaches, are just beginning to be introduced in Chilean HAB monitoring, and the procedures have not yet been standardized. Here, 16S rRNA and 18S rRNA metabarcoding analyses for monitoring Chilean HABs are introduced stepwise. According to a recent hypothesis, algal-bacterial mutualistic association plays a critical synergetic or antagonistic relationship accounting for bloom initiation, maintenance, and regression. Thus, monitoring HAB from algal-bacterial perspectives may provide a broader understanding of HAB mechanisms and the basis for early warning. Metabarcoding analysis is one of the best suited molecular-based tools for this purpose because it can detect massive algal-bacterial taxonomic information in a sample. The visual procedures of sampling to metabarcoding analysis herein provide specific instructions, aiming to reduce errors and collection of reliable data.
Subject(s)
Aquaculture , Harmful Algal Bloom , Chile , RNA, Ribosomal, 16S/geneticsABSTRACT
In Chile, the toxic dinoflagellate A. catenella shows an apparent oceanic range expansion from south to the north since its first detection in 1972 in the Magallanes Region (56° S). Until 2017, A. catenella detections were restricted to a geographic area between Magallanes to Los Rios Regions (40° S). The establishment of a monitoring program in the offshore Pacific coast allowed the detection of A. catenella between 2018 and 2019 in northern areas off the Bío-Bío Region (36°S). Monoclonal cultures established from the Bío-Bío coast were genetically identified, and PSTs screened. Phylogenetic analyses determined that the Bío-Bío isolates aggregated in Group I ribotype (previously A. tamarense or A. fundyense) and the presence of PSTs analogs were confirmed. It is the northernmost detection of the toxic dinoflagellate A. catenella in the Pacific coast of Chile. These results have important implications for species monitoring and governmental management in the Bío-Bío Region.
Subject(s)
Dinoflagellida , Shellfish Poisoning , Chile , Humans , Oceans and Seas , PhylogenyABSTRACT
Phytoplankton blooms, including harmful algal blooms (HABs), have serious impacts on ecosystems, public health, and productivity activities. Rapid detection and monitoring of marine microalgae are important in predicting and managing HABs. We developed a toolkit, the Suitcase Lab, to detect harmful algae species in the field. We demonstrated the Suitcase Lab's capabilities for sampling, filtration, DNA extraction, and loop-mediated isothermal amplification (LAMP) detection in cultured Alexandrium catenella cells as well as Chilean coastal waters from four sites: Repollal, Isla García, Puerto Montt, and Metri. A LAMP assay using the Suitcase Lab in the field confirmed microscopic observations of A. catenella in samples from Repollal and Isla García. The Suitcase Lab allowed the rapid detection of A. catenella, within 2 h from the time of sampling, even at a single cell per milliliter concentrations, demonstrating its usefulness for quick and qualitative on-site diagnosis of target toxic algae species. This method is applicable not only to detecting harmful algae but also to other field studies that seek a rapid molecular diagnostic test.
Subject(s)
Dinoflagellida , Ecosystem , Chile , Dinoflagellida/genetics , Harmful Algal Bloom , Molecular Diagnostic Techniques , Nucleic Acid Amplification TechniquesABSTRACT
Blocking the interaction between the Gßγ protein and the glycine receptor (GlyR) has emerged as a promising pharmacological strategy to treat acute alcohol intoxication by inhibiting ethanol potentiation on GlyR. M554 is a recently discovered small molecule capable of binding to Gßγ with potent in vitro and in vivo inhibitory activity. This compound has been tested as a mixture of diastereomers, and no information is available concerning the stereospecific activity of each species, which is critical to pursue efforts on lead optimization and drug development. In this work, we explored the differential activity of four M554 stereoisomers by in silico molecular dynamics simulations and electrophysiological experiments. Our results revealed that the (R,R)-M554 stereoisomer is a promising lead compound that inhibits ethanol potentiation of GlyR.
Subject(s)
Ethanol , Receptors, Glycine , StereoisomerismABSTRACT
Karenia selliformis is a bloom-forming toxic dinoflagellate known for production of gymnodimines (GYMs) and causing mass mortalities of marine fauna. Blooms have been reported from coastal waters of New Zealand, Mexico, Tunisia, Kuwait, Iran, China and Chile. Based on molecular phylogeny, morphology, toxin production, pigment composition and cell growth of Chilean K. selliformis isolated in 2018 (CREAN_KS01 and CREAN_KS02), this study revealed a more complex diversity within this species than previously thought. A phylogenetic reconstruction based on the large sub-unit ribosomal nucleotide (LSU rDNA) and Internal Transcriber Spacer (ITS) sequences of 12 worldwide isolates showed that within the K. selliformis clade there are at least two different phylotypes with clear phenotypic differences. Morphological differences related to the dorsal-ventral compression, shape of the hyposome and the presence of pores on the left lobe of the hyposome. A comparison of pigment signatures among worldwide isolates revealed the existence of both acyl-oxyfucoxanthin and fucoxanthin-rich strains within the phylotypes. A LC-MS/MS screening on both Chilean 2018 K. selliformis strains showed for first time no GYMs production among cultured clones of this species. However, both CREAN_KS01 and CREAN_KS02 contained two compounds with the same mass transition as brevenal, a brevetoxin related compound. A fish gill cell-based assay showed that the CREAN_KS02 strain was highly cytotoxic but pure GYM standard did not exhibit loss of cell viability, even at cell concentrations equivalent or exceeding those reported in nature. The fatty acid profile of CREAN_KS02 included high levels of saturated (14:0; 16:0) and polyunsaturated (18:3ω6+18:5ω3; 22:6ω3) fatty acids but superoxide production in this strain was low (0.86±0.53 pmol O2- cell-1 h-1). A factorial T-S growth experiment using the CREAN_KS02 strain showed a µmax of 0.41±0.03 d-1 at high salinity and temperature, which points to its optimal environmental niche in offshore waters during the summer season. In conclusion, the present study provides evidence for significant genetic and phenotypic variability among worldwide isolates, which points to the existence of a K. selliformis "species complex". The massive fauna mortality during K. selliformis bloom events in the Chilean coast cannot be explained by GYMs nor brevetoxins, but can to a large extent be accounted for by the high production of long-chain PUFAs and/or still uncharacterized highly toxic compounds.
Subject(s)
Dinoflagellida , Tandem Mass Spectrometry , Animals , Chile , China , Chromatography, Liquid , Dinoflagellida/genetics , New Zealand , Phylogeny , TunisiaABSTRACT
Harmful algae blooms (HABs) cause acute effects on marine ecosystems due to their production of endogenous toxins or their enormous biomass, leading to significant impacts on local economies and public health. Although HAB monitoring has been intensively performed at spatiotemporal scales in coastal areas of the world over the last decades, procedures have not yet been standardized. HAB monitoring procedures are complicated and consist of many methodologies, including physical, chemical, and biological water sample measurements. Each monitoring program currently uses different combinations of methodologies depending on site specific purposes, and many prior programs refer to the procedures in quotations. HAB monitoring programs in Chile have adopted the traditional microscopic and toxin analyses but not molecular biology and bacterial assemblage approaches. Here we select and optimize the HAB monitoring methodologies suitable for Chilean geography, emphasizing on metabarcoding analyses accompanied by the classical tools with considerations including cost, materials and instrument availability, and easiness and efficiency of performance. We present results from a pilot study using the standardized stepwise protocols, demonstrating feasibility and plausibility for sampling and analysis for the HAB monitoring. Such specific instructions in the standardized protocol are critical obtaining quality data under various research environments involving multiple stations, different analysts, various time-points, and long HAB monitoring duration.
Subject(s)
Aquaculture , Ecosystem , Fisheries , Harmful Algal Bloom , Chile , Pilot ProjectsABSTRACT
Colchicine is a plant alkaloid that is widely used as a therapeutic agent. It is widely accepted that colchicine reduces the production of inflammatory mediators mainly by altering cytoskeleton dynamics due to its microtubule polymerization inhibitory activity. However, other lines of evidence have shown that colchicine exerts direct actions on the function of ion channels, which are independent of cytoskeleton alterations. Colchicine is able to modify the function of several pentameric ligand-gated ion channels, including glycine receptors (GlyRs). Previous electrophysiological studies have shown that colchicine act as an antagonist of GlyRs composed by the α 1 subunit. In addition, it was recently demonstrated that colchicine directly bind to the α 3 subunit of GlyRs. Interestingly, other studies have shown a main role of α 3GlyRs on chronic inflammatory pain. Nevertheless, the functional effects of colchicine on the α 3GlyR function are still unknown. Here, by using electrophysiological techniques and bioinformatics, we show that colchicine inhibited the function of the α 3GlyRs. Colchicine elicited concentration-dependent inhibitory effects on α 3GlyRs at micromolar range and decreased the apparent affinity for glycine. Single-channel recordings show that the colchicine inhibition is associated with a decrease in the open probability of the ion channel. Molecular docking assays suggest that colchicine preferentially bind to the orthosteric site in the closed state of the ion channel. Altogether, our results suggest that colchicine is a competitive antagonist of the α 3GlyRs.
ABSTRACT
The neurulation process is regulated by a large amount of genetic and environmental factors that determine the establishment, folding, and fusion of the neural plate to form the neural tube, which develops into the main structure of the central nervous system. A recently described factor involved in this process is glutamate. Through NMDA ionotropic receptor, glutamate modifies intracellular Ca2+ dynamics allowing the oriented cell migration and proliferation, essentials processes in neurulation. Glutamate synthesis depends on the mitochondrial enzyme known as glutaminase 1 (GLS1) that is widely expressed in brain and kidney. The participation of GLS 1 in prenatal neurogenic processes and in the adult brain has been experimentally established, however, its participation in early stages of embryonic development has not been described. The present investigation describes for the first time the presence and functionality of GLS1 in Xenopus laevis embryos during neurulation. Although protein expression levels remains constant, the catalytic activity of GLS1 increases significantly (~66%) between early (stage 12) and middle to late (stages 14-19) neurulation process. Additionally, the use of 6-diazo-5-oxo-L-norleucine (L-DON, competitive inhibitor of glutamine-depend enzymes), reduced significantly the GLS1 specific activity during neurulation (~36%) and induce the occurrence of neural tube defects involving its possible participation in the neural tube closure in Xenopus laevis embryos.
ABSTRACT
Alzheimer's disease (AD) is a neurodegenerative disorder characterized by cognitive impairment that increasingly afflicts the elderly population. Soluble oligomers (AßOs) has been implicated in AD pathogenesis: however, the molecular events underlying a role for Aß are not well understood. We studied the effects of AßOs on mitochondrial function and on key proteins that regulate mitochondrial dynamics and biogenesis in hippocampal neurons and PC-12 cells. We find that AßOs treatment caused a reduction in total Mfn1 after a 2 h exposure (42 ± 11%); while DRP1 increased at 1 and 2 h (205 ± 22% and 198 ± 27%, respectively), correlating to changes in mitochondrial morphology. We also observed that SIRT1 levels were reduced after acute and chronic AßOs treatment (68 ± 7% and 77 ± 6%, respectively); while PGC-1α levels were reduced with the same time treatments (68 ± 8% and 67 ± 7%, respectively). Interestingly, we found that chronic treatment with AßOs increased the levels of pSIRT1 (24 h: 157 ± 18%), and we observed changes in the PGC-1α and p-SIRT1 nucleus/cytosol ratio and SIRT1-PGC-1α interaction pattern after chronic exposure to AßOs. Our data suggest that AßOs induce important changes in the level and localization of mitochondrial proteins related with the loss of mitochondrial function that are mediated by a fast and sustained SIRT1/PGC-1α complex disruption promoting a "non-return point" to an irreversible synaptic failure and neuronal network disconnection.
ABSTRACT
OBJECTIVE: To compare the duration (hours until HCO3- ≥ 15 mmol/L) of diabetic ketoacidosis (DKA) episodes that are the first manifestation of new type 1 diabetes (NT1D) and those that are a complication in patients with previously diagnosed type 1 diabetes (PT1D). METHODS: A multicenter retrospective cohort study was designed. The duration of DKA was measured from the start of the treatment. The primary outcome was the comparison of the time needed in each group to reach HCO3- ≥ 15 mmol/L. The secondary outcomes were the comparison of the time to reach pH ≥ 7.3 and length of hospital stay in each group. Data were analyzed with a bivariate analysis of the variables vs primary outcome. Then, a regression model was analyzed. Results There were 305 episodes included (NT1D: 115, PT1D: 190). DKA in the NT1D group lasted longer (NT1D 20 (16-19) vs PT1D 12 (8-16), hours, P < .01) with a significant difference in each level of DKA severity. This group also took longer to reach pH ≥ 7.3 (NT1D 16 (12-22) vs PT1D 9 (6-12), hours, P < .01) and had a longer hospital stay (NT1D 9 (6-12) vs PT1D 7 (4-10), hours, P < .01). CONCLUSION: The duration of DKA is longer in patients with NT1D regardless of characteristics like DKA severity, duration of symptoms, and type of treatments received.
Subject(s)
Diabetes Mellitus, Type 1 , Diabetic Ketoacidosis/epidemiology , Diabetic Ketoacidosis/pathology , Age of Onset , Child , Cohort Studies , Colombia/epidemiology , Diabetes Mellitus, Type 1/complications , Diabetes Mellitus, Type 1/epidemiology , Diabetes Mellitus, Type 1/therapy , Diabetic Ketoacidosis/therapy , Disease Progression , Female , Humans , Length of Stay/statistics & numerical data , Male , Retrospective Studies , Severity of Illness Index , Time FactorsABSTRACT
Glycine receptors (GlyRs) are anion-permeable pentameric ligand-gated ion channels (pLGICs). The GlyR activation is critical for the control of key neurophysiological functions, such as motor coordination, respiratory control, muscle tone and pain processing. The relevance of the GlyR function is further highlighted by the presence of abnormal glycinergic inhibition in many pathophysiological states, such as hyperekplexia, epilepsy, autism and chronic pain. In this context, previous studies have shown that the functional inhibition of GlyRs containing the α3 subunit is a pivotal mechanism of pain hypersensitivity. This pathway involves the activation of EP2 receptors and the subsequent PKA-dependent phosphorylation of α3GlyRs within the intracellular domain (ICD), which decrease the GlyR-associated currents and enhance neuronal excitability. Despite the importance of this mechanism of glycinergic dis-inhibition associated with dysfunctional α3GlyRs, our current understanding of the molecular events involved is limited. Here, we report that the activation of PKA signaling pathway decreases the unitary conductance of α3GlyRs. We show in addition that the substitution of the PKA-targeted serine with a negatively charged residue within the ICD of α3GlyRs and of chimeric receptors combining bacterial GLIC and α3GlyR was sufficient to generate receptors with reduced conductance. Thus, our findings reveal a potential biophysical mechanism of glycinergic dis-inhibition and suggest that post-translational modifications of the ICD, such as phosphorylation, may shape the conductance of other pLGICs.
Subject(s)
Excitatory Postsynaptic Potentials , Receptors, Glycine/metabolism , Receptors, Glycine/physiology , Amino Acid Substitution , Cyclic AMP-Dependent Protein Kinases/metabolism , Humans , Intracellular Space/metabolism , Phosphorylation , Protein Domains , Protein Processing, Post-Translational , Receptors, Glycine/chemistry , Receptors, Prostaglandin E, EP2 Subtype , Signal TransductionABSTRACT
Neuroligin-1 (NL1) is a postsynaptic cell adhesion protein that plays a crucial role in synapsis and signaling between neurons. Due to its clustered distribution in synaptic clefts, NL1 appears as a novel potential site for synaptic targeting purposes. In this work, in silico protein topography analysis was employed to identify two prospective binding sites on the NL1 dimer surface in the 2:2 synaptic adhesion complex with ß-neurexin (PDB code 3B3Q ). Receptor-based rational design, cell-penetrating capability prediction, molecular docking, molecular dynamics simulations, and binding free energy calculations were used to identify five heptapeptides candidates with favorable predicted profiles as non cell-penetrating NL1-binding agents. Preliminary in vitro colocalization assays with NL1-transfected HEK 293 cells confirmed that peptides remain in the extracellular space without inducing detectable changes in cell morphology. The highest NL1-colocatization capability was attained by the peptide ADEAIVA, which appears as a promising candidate for the future development of specific NL1-targeting systems as part of synapse-directed therapies against central nervous system diseases.