Evaluación de la cariogenicidad de Actinomyces naeslundii, Streptococcus gordonii y Streptococcus mutans en un modelo de biofilm multiespecies

58 p.Objetivo: La formación de biopelículas y cariogenicidad difieren mucho entre las distintas especies que pueblan el biofilm oral. Estas bacterias también pueden competir para prevalecer durante el desarrollo del biofilm. La mayoría de los estudios sobre el metabolismo de los hidratos de carbono por las bacterias cariogénicas se han llevado a cabo usando biofilm monoespecies o duales. El modelo de biofilms con más de dos especies es escasamente reportado y sólo unos pocos informes han abordado esta cuestión. Por lo tanto, el propósito de este estudio fue determinar la cariogenicidad sobre el esmalte de A. naeslundii, S. gordonii, y S. mutans después que ellos formaron parte de un modelo de biopelícula multiespecies. Materiales y Métodos: Biofilms de A. naeslundii ATCC12104, S. gordonii ATCC35105 y S. mutans UA159 y las tres especies juntas fueron cultivados, sobre bloques de esmalte bovino y crecidos en caldo de cultivo triptona-extracto de levadura ultrapurificado (UYTEB) con glucosa al 1% a 37ºC y 10% CO2, durante 4 días. Ocho veces al día los biofilms fueron expuestos a 10% de sacarosa. El pH de los medios de cultivo se determinó 2 veces por día. En el día 5 los biofilms fueron colectados para la evaluación de: a) biomasa de biofilms (viabilidad bacteriana, peso húmedo), b) concentración extracelular de polisacáridos solubles e insolubles, c) concentración de polisacáridos intracelulares, d) observación de las biopelículas mediante microscopía electrónica de barrido y microscopía confocal. La desmineralización de los bloques dentarios fue estimada por el porcentaje de pérdida de microdureza superficial (%PDS). Los resultados se compararon entre biofilms monospecies y multiespecies a un nivel de significación del 95%. Resultados: S. mutans solo fue más acidogénica (pH a 82 h: 4,41 ± 0,10, n= 6), mostrando una mayor concentración de polisacáridos extracelulares insolubles (15,8 ± 6,1, n=6) e induciendo más %PDS en el esmalte (45,3 ± 4,8, n= 6) que las otras especies que crecen en biofilms monoespecies, pero también del multiespecies. Conclusiones: Los datos sugieren que cariogenicidad de S. mutans se ve obstaculizada cuando crece junto con S. gordonii y A. naeslundii en una biopelícula multiespecífica. Palabras clave: Biofilm multiespecies, A. naeslundii, S. gordonii, S. mutans, cariogenicidad, sacarosa./ABSTRACT: Assessment of the cariogenicity of Actinomyces naeslundii, Streptococcus gordonii and Streptococcus mutans on a multispecies biofilm model. Objective: Biofilm formation and cariogenicity greatly differ among the various species populating the oral biofilm. These bacteria can also compete to prevail during the development of the biofilm. Studies dealing with the metabolism of carbohydrates by cariogenic bacteria have mostly carried out using mono or dual-species biofilms. Modeling using more than two species is scarce and only few reports have addresses this issue. Therefore, the purpose of this study was to determine cariogenicity on enamel of A. naeslundii, S. gordonii, and S. mutans after when they are forming part of a multispecies biofilm model. Materials and Methods: Biofilms of A. naeslundii ATCC12104, S. gordonii ATCC35105 and S. mutans UA159 by separate and together were grown on bovine enamel slabs into tryptone-yeast extract ultrapurified (UYTEB) growth medium, supplemented with 1% glucose at 37°C and 10% CO2 for 4 days. Eight times a day biofilms were exposed to 10% sucrose. The pH of the culture media was determined twice per day. On day 5, biofilms were collected for assessment of: a) biofilms biomass (bacterial viability, wet weight), b) extracellular concentration of soluble and insoluble polysaccharides, c) concentration of intracellular polysaccharides and d) observation of the biofilms by SEM and confocal microscopy. Demineralization of the slabs was estimated by the percentage of surface microhardness loss (%SHL). Results were compared between monospecies and multispecies biofilms at a level of 95% of significance. Results: S. mutans alone was more acidogenic (pH at 82 h: 4.41±0.10, n=6), showing higher concentration of insoluble extracellular polysaccharides (15.8±6.1, n=6) and inducing more %SHL in enamel (45.3±4.8, n=6) than the other species growing in monoespecies, but also than the multispecies. Conclusions: Data suggest that cariogenicity of S. mutans is hampered when it grows along with S. gordonii and A. naeslundii in a multispecies biofilm. Keywords: Multispecies biofilm, S. gordonii, S. mutans, A. naeslundii, carcinogenicity, sucrose

Academics' Experiences in Veterinary Educational Research : Results of an International Survey

Research conducted by the veterinary education community is critical to continual improvement of educational outcomes. Additionally, research productivity is one metric in promotion and tenure decisions. We sought to identify challenges encountered or anticipated when undertaking or planning veterinary educational research (VER), to learn how these challenges might be overcome, and to synthesize tips for success from those who have performed VER. A branching survey was developed and deployed along the authors' worldwide veterinary education contacts in a cascading manner. The survey collected quantitative and qualitative information from participants who had performed VER and those who planned to perform VER in the future. The 258 participants represented 41 countries. Of the participants, 204 had performed VER (79%) and 54 planned to in the future (21%). The median time spent teaching was 14 years, and median time performing VER was 5 years. The most commonly reported challenges in performing VER were lack of funding, lack of time, and difficulties encountered when undertaking a study, including data collection, analysis, and publishing. When asked about overcoming the challenges, a major theme emerged around people, who provided expertise and mentoring. The most commonly reported tip for success was collaboration; 73% of experienced researchers reported people as most helpful upon beginning VER. Collaborators provided diverse help with ideas, study design, statistics, and other aspects. These results suggest that institutions can offer support to academics in the form of small grants, protected research time, writing workshops, and mentorship to assist with the production of meaningful VER.Peer reviewe

Effect of ionic strength on the formal potential of the glass electrode in various saline media

We examined the variation with ionic strength (I, adjusted with KCl, KNO3, KBr, NaCl or NaClO4) of the formal potential (Econst) for glass electrodes exhibiting a Nernstian response (i.e. Ecell=Econst−s log [H+]). For this purpose, we investigated the different factors included in the formal potential, so we obtained reported values for the liquid junction potential as a function of ionic strength and determined the logarithm of the activity coefficient for the proton in various saline media, using Pitzer equations

Pyronaridine exerts potent cytotoxicity on human breast and hematological cancer cells through induction of apoptosis

The potent antimalarial drug pyronaridine (PND) was tested for its potential as an anticancer drug. After exposing cancerous (17) and non-cancerous (2) cells to PND for 72 hr, PND was found to exhibit consistent and potent cytotoxic activity at low micromolar (μM) concentrations that ranged from 1.6 μM to 9.4 μM. Moreover, PND exerted a significant selective cytotoxicity index (SCI) on five out of seven breast cancer cell lines tested, with favorable values of 2.5 to 4.4, as compared with the non-cancerous breast MCF-10A cell line. By using the same comparison, PND exhibited a significant SCI on three out of four leukemia/lymphoma cell lines with promising values of 3.3 to 3.5. One breast cancer and one leukemia cell line were tested further in order to determine the likely mode of action of PND. PND was found to consistently elicit phosphatidylserine externalization, mitochondrial depolarization, and DNA fragmentation, in both the triple negative MDA-MB-231 breast cancer and HL-60 leukemia cell lines. In addition, PND treatment altered cell cycle progression in both cancer cells. Subsequent DNA mobility-shift assays, UV-Visible spectroscopic titrations, and circular dichroism (CD) experiments revealed that PND intercalates with DNA. The findings presented in this study indicates that PND induces apoptosis and interfered with cell cycle progression of cancer cell lines and these results indicate that this drug has the potential as a repurposed drug for cancer therapy

New phylogenetic insights into Saprolegniales (Oomycota, Straminipila) based upon studies of specimens isolated from Brazil and Argentina

Saprolegniales is a complex and monophyletic order of oomycetes. Their members inhabit terrestrial, freshwater, and marine ecosystems and have a worldwide distribution. In these ecosystems, they are found as saprobes, parasites, or even pathogens of animals and plants of economic importance. In this study, a concatenate phylogeny of the partial LSU and complete ITS rDNA regions is presented, including isolates from Brazil and Argentina, which were sequenced after a detailed morphological analysis. Among the sequenced species, Achlya orion, Leptolegnia eccentrica, Phragmosporangium uniseriatum, and Pythiopsis irregularis are included for the first time in a phylogeny. Our results are in agreement with the recent informal proposals outlined in taxonomic overviews of the Oomycota of G.W. Beakes and collaborators, who placed the family Verrucalvaceae into the Saprolegniales and introduced the family Achlyaceae to group Achlya s.s., Brevilegnia, Dictyuchus, and Thraustotheca. These results also support the transference of Achlya androgyna to Newbya. Leptolegnia appears as paraphyletic, with the separation of L. eccentrica from the other species of this genus. In addition, Phragmosporangium, which is herein sequenced for the first time, clustered as sister to some species of Aphanomyces, including the type species, A. stellatus.Fil: Rocha, Sarah C. O.. Instituto de Botânica. Núcleo de Pesquisa em Micologia; BrasilFil: Lopez Lastra, Claudia Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; ArgentinaFil: Marano, Agostina Virginia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Instituto de Botânica. Núcleo de Pesquisa em Micologia; BrasilFil: de Souza, José Ivanildo. Instituto de Botânica. Núcleo de Pesquisa em Micologia; BrasilFil: Rueda Páramo, Manuel Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; ArgentinaFil: Pires Zottarelli, Carmen L. A.. Instituto de Botânica. Núcleo de Pesquisa em Micologia; Brasi

Assumption-Free Estimation of Heritability from Genome-Wide Identity-by-Descent Sharing between Full Siblings

The study of continuously varying, quantitative traits is important in evolutionary biology, agriculture, and medicine. Variation in such traits is attributable to many, possibly interacting, genes whose expression may be sensitive to the environment, which makes their dissection into underlying causative factors difficult. An important population parameter for quantitative traits is heritability, the proportion of total variance that is due to genetic factors. Response to artificial and natural selection and the degree of resemblance between relatives are all a function of this parameter. Following the classic paper by R. A. Fisher in 1918, the estimation of additive and dominance genetic variance and heritability in populations is based upon the expected proportion of genes shared between different types of relatives, and explicit, often controversial and untestable models of genetic and non-genetic causes of family resemblance. With genome-wide coverage of genetic markers it is now possible to estimate such parameters solely within families using the actual degree of identity-by-descent sharing between relatives. Using genome scans on 4,401 quasi-independent sib pairs of which 3,375 pairs had phenotypes, we estimated the heritability of height from empirical genome-wide identity-by-descent sharing, which varied from 0.374 to 0.617 (mean 0.498, standard deviation 0.036). The variance in identity-by-descent sharing per chromosome and per genome was consistent with theory. The maximum likelihood estimate of the heritability for height was 0.80 with no evidence for non-genetic causes of sib resemblance, consistent with results from independent twin and family studies but using an entirely separate source of information. Our application shows that it is feasible to estimate genetic variance solely from within-family segregation and provides an independent validation of previously untestable assumptions. Given sufficient data, our new paradigm will allow the estimation of genetic variation for disease susceptibility and quantitative traits that is free from confounding with non-genetic factors and will allow partitioning of genetic variation into additive and non-additive components

Revised fission yeast gene and allele nomenclature guidelines for machine readability

Standardized nomenclature for genes, gene products, and isoforms is crucial to prevent ambiguity and enable clear communication of scientific data, facilitating efficient biocuration and data sharing. Standardized genotype nomenclature, which describes alleles present in a specific strain that differ from those in the wild-type reference strain, is equally essential to maximize research impact and ensure that results linking genotypes to phenotypes are Findable, Accessible, Interoperable, and Reusable (FAIR). In this publication, we extend the fission yeast clade gene nomenclature guidelines to support the curation efforts at PomBase (www.pombase.org), the Schizosaccharomyces pombe Model Organism Database. This update introduces nomenclature guidelines for noncoding RNA genes, following those set forth by the Human Genome Organisation Gene Nomenclature Committee. Additionally, we provide a significant update to the allele and genotype nomenclature guidelines originally published in 1987, to standardize the diverse range of genetic modifications enabled by the fission yeast genetic toolbox. These updated guidelines reflect a community consensus between numerous fission yeast researchers. Adoption of these rules will improve consistency in gene and genotype nomenclature, and facilitate machine-readability and automated entity recognition of fission yeast genes and alleles in publications or datasets. In conclusion, our updated guidelines provide a valuable resource for the fission yeast research community, promoting consistency, clarity, and FAIRness in genetic data sharing and interpretation

Seagrasses in the Age of Sea Turtle Conservation and Shark Overfishing

Efforts to conserve globally declining herbivorous green sea turtles have resulted in promising growth of some populations. These trends could significantly impact critical ecosystem services provided by seagrass meadows on which turtles feed. Expanding turtle populations could improve seagrass ecosystem health by removing seagrass biomass and preventing of the formation of sediment anoxia. However, overfishing of large sharks, the primary green turtle predators, could facilitate turtle populations growing beyond historical sizes and trigger detrimental ecosystem impacts mirroring those on land when top predators were extirpated. Experimental data from multiple ocean basins suggest that increasing turtle populations can negatively impact seagrasses, including triggering virtual ecosystem collapse. Impacts of large turtle populations on seagrasses are reduced in the presence of intact shark populations. Healthy populations of sharks and turtles, therefore, are likely vital to restoring or maintaining seagrass ecosystem structure, function, and their value in supporting fisheries and as a carbon sink