Quantitative PCR reveals the frequency and distribution of 3 indigenous yeast species across a range of specialty cheeses

Indigenous microorganisms are important components of the complex ecosystem of many dairy foods including cheeses, and they are potential contributors to the development of a specific cheese's sensory properties. Among these indigenous microorganisms are the yeasts Cyberlindnera jadinii, Pichia kudriavzevii, and Kazachstania servazzii, which were previously detected using traditional microbiological methods in both raw milk and some artisanal specialty cheeses produced in the province of Québec, Canada. However, their levels across different cheese varieties are unknown. A highly specific and sensitive real-time quantitative PCR assay was developed to quantitate these yeast species in a variety of specialty cheeses (bloomy-rind, washed-rind, and natural-rind cheeses from raw, thermized, and pasteurized milks). The specificity of the quantitative PCR assay was validated, and it showed no cross-amplification with 11 other fungal microorganisms usually found in bloomy-rind and washed-rind cheeses. Cyberlindnera jadinii and P. kudriavzevii were found in the majority of the cheeses analyzed (25 of 29 and 24 of 29 cheeses, respectively) in concentrations up to 104 to 108 gene copies/g in the cheese cores, which are considered oxygen-poor environments, and 101 to 104 gene copies/cm2 in the rind. However, their high abundance was not observed in the same samples. Whereas C. jadinii was present and dominant in all core and rind samples, P. kudriavzevii was mostly present in cheese cores. In contrast, K. servazzii was present in the rinds of only 2 cheeses, in concentrations ranging from 101 to 103 gene copies/cm2, and in 1 cheese core at 105 gene copies/g. Thus, in the ecosystems of specialty cheeses, indigenous yeasts are highly frequent but variable, with certain species selectively present in specific varieties. These results shed light on some indigenous yeasts that establish during the ripening of specialty cheeses

O PAPEL DA EXPERIÊNCIA NA APRENDIZAGEM NA PROFISSÃO DOCENTE: UMA REVISÃO DA LITERATURA

This article questions the role of experience in a pre-service teacher education practicum context. Although studied for several decades, experiential learning still has several gray areas. In order to shed light on the phenomenon, a literature review was conducted on scientific writings produced in the educational domain between 2000 and 2021. Three thematic categories emerged from a meta-analysis on experiential learning (framework, foundations and organizers, and knowledge), allowing a global understanding of its role and its limits, of its foundations, organizers and the training devices that frame it, and finally, of the nature of its product which is experiential knowledge.Este artículo cuestiona el rol de la experiencia en contexto de la formación práctica de la profesión docente. Aunque se ha estudiado durante varias décadas, el aprendizaje experiencial todavía tiene varias áreas grises. Para arrojar luz en este tema, se realizó una revisión de los escritos científicos producidos en educación entre 2000 y 2021. De un meta-análisis surgieron tres categorías temáticas del aprendizaje experiencial (marcos, fundamentos y organizadores y saberes emanados) que permiten una comprensión global de su rol y sus límites, de sus fundamentos, organizadores y dispositivos de formación que lo fomentan y, finalmente, de los saberes que emanan del conjunto de los procesos.Este artigo questiona o papel da aprendizagem experimental no contexto da formação prática de professores. Embora estudada durante várias décadas, a aprendizagem experimental ainda tem várias áreas de indefinição. Para esclarecer esta questão, foi realizada uma revisão dos escritos científicos produzidos na educação entre 2000 e 2021. Uma meta-análise revelou três categorias temáticas de aprendizagem experimental (quadros, fundações e organizadores, e conhecimentos emanados) que permitem uma compreensão global do seu papel e dos seus limites, das suas fundações, organizadores e dispositivos de formação que a promovem, e finalmente, do conhecimento que emana dos processos como um todo

Limitations in a frataxin knockdown cell model for Friedreich ataxia in a high-throughput drug screen

<p>Abstract</p> <p>Background</p> <p>Pharmacological high-throughput screening (HTS) represents a powerful strategy for drug discovery in genetic diseases, particularly when the full spectrum of pathological dysfunctions remains unclear, such as in Friedreich ataxia (FRDA). FRDA, the most common recessive ataxia, results from a generalized deficiency of mitochondrial and cytosolic iron-sulfur cluster (ISC) proteins activity, due to a partial loss of frataxin function, a mitochondrial protein proposed to function as an iron-chaperone for ISC biosynthesis. In the absence of measurable catalytic function for frataxin, a cell-based assay is required for HTS assay.</p> <p>Methods</p> <p>Using a targeted ribozyme strategy in murine fibroblasts, we have developed a cellular model with strongly reduced levels of frataxin. We have used this model to screen the Prestwick Chemical Library, a collection of one thousand off-patent drugs, for potential molecules for FRDA.</p> <p>Results</p> <p>The frataxin deficient cell lines exhibit a proliferation defect, associated with an ISC enzyme deficit. Using the growth defect as end-point criteria, we screened the Prestwick Chemical Library. However no molecule presented a significant and reproducible effect on the proliferation rate of frataxin deficient cells. Moreover over numerous passages, the antisense ribozyme fibroblast cell lines revealed an increase in frataxin residual level associated with the normalization of ISC enzyme activities. However, the ribozyme cell lines and FRDA patient cells presented an increase in Mthfd2 transcript, a mitochondrial enzyme that was previously shown to be upregulated at very early stages of the pathogenesis in the cardiac mouse model.</p> <p>Conclusion</p> <p>Although no active hit has been identified, the present study demonstrates the feasibility of using a cell-based approach to HTS for FRDA. Furthermore, it highlights the difficulty in the development of a stable frataxin-deficient cell model, an essential condition for productive HTS in the future.</p

The Master-Pieces : A Walk through the Flowers

This visitor's guide highlights the motif of the flower in certain works from the museum's permanent collection, selected among paintings, photographs and decorative objets from the 17th century to the present

Vers l’identification d’assemblages phytoplanctoniques depuis l’espace à travers le couplage innovant d’analyses des luminances et de données in-situ, perspectives pour l’étude des habitats et des réponses des assemblages

pdf non compressé disponible sur [email protected] the past years, a large number of new approaches in the domain of ocean color have been developedto study phytoplankton ocean processes based on phytoplankton size classes and functionaltypes. One of these methods, named PHYSAT, currently allows for the qualitative identificationof five main phytoplankton groups from remote sensing measurements (Alvain et al., 2008). Thismethod established empirical relationships between in-situ dominant phytoplankton groups andspecific ocean color radiance anomalies in open ocean waters. These radiance anomalies are definedby specific shape and amplitude according to the dominant phytoplancton group in waters. Thetheoretical explanation of PHYSAT (Alvain et al., 2012) showed that radiance anomalies are inducedby a combination of inherent optical properties (absorption and backscattering coefficients,absorption of colored dissolved organic matters). This study suggested that the empiric identificationof dominant cases represents an under-exploitation of the radiance anomalies. The workpresented here adresses the potential development of the PHYSAT method toward the empiricidentification of phytoplankton assemblages. A global ocean (based on biomarker pigments data)and a regional sea’s (North Sea, based on CPR abundance data) applications are presented. Ourresults show, for the first time, the ability of PHYSAT to identify phytoplankton assemblages usingempirical relationships with radiance anomalies, beyond the identification of dominance cases only.This work was facilitated by the use of previous mathematical classification of radiance anomaliesin terms of shape and amplitude (using a self-organizing map, Ben Mustapha et al. (2014), coupledwith a new classification that take into account the phenology of radiance anomalies types.This work emphasizes the potential of PHYSAT’s radiance anomalies when using new classificationtools, and detailed in-situ databases. Future directions are listed to understand the empiricalrelationships observed in this work beyond the current theoretical knowledge.L’identification des groupes phytoplanctoniques depuis l’espace présente un fort intérêt pour denombreux domaines de recherche en lien avec l’étude des océans. Afin de fournir des observationsattendues par la communauté scientifique, différentes approches ont été développées, et permettentd’obtenir des informations en lien avec la taille ou des groupes fonctionnels de phytoplancton depuisles mesures effectuées par des radiomètres à bord de satellites. Cette thèse a eu pour cadre le développementd’une méthode initiée en 2005, nommée PHYSAT. Cette dernière est initialement baséesur la mise en évidence de relations empiriques entre des anomalies de luminance et la présence d’ungroupe phytoplanctonique dominant. Alvain et al. (2008) ont ainsi permis l’identification de cinqgroupes phytoplanctoniques lorsqu’ils sont dominants, via la détermination empirique d’anomaliesde luminance dont les amplitudes et formes spectrales, aux longueurs d’ondes visibles des capteursde couleur de l’océan, sont spécifiques à la présence de ces groupes. Une étude théorique (Alvainet al., 2012) a, par ailleurs, permis d’apporter une première explication théorique à la présencede ces anomalies de luminance, en tenant compte des propriétés optiques inhérentes (coefficientd’absorption, de rétrodiffusion et absorption des matières dissoutes colorées). Ces résultats théoriquesformulaient l’hypothèse que l’identification des cas de dominance uniquement représentaitune sous-utilisation du potentiel d’informations porté par les anomalies de luminance. Dans cettethèse, nous avons donc évalué le potentiel de développement de la méthode PHYSAT au-delà de ladominance, vers l’identification empirique d’assemblages phytoplanctoniques. Cela a nécessité, enpremier lieu, une adaptation de la chaîne de traitement de la méthode. En effet, les anomalies deluminance étaient classées jusqu’à la dernière version (Ben Mustapha et al., 2014) uniquement àl’aide d’une carte auto-organisatrice des caractéristiques spectrales (classification mathématique).Cette approche ne prenait pas pleinement en compte les caractéristiques spatio-temporelles des anomalies.Il a donc été proposé une nouvelle approche, plus adaptée, basée sur les outils issus de laphénologie, associés à une approche innovante concernant l’analyse des données in-situ elle-même.Ensuite, le potentiel de développement de PHYSAT vers l’identification empirique des assemblagesa été évalué dans une étude globale à partir de données de pigments biomarqueurs, ainsi que dansune étude régionale en Mer du Nord, à partir des données CPR. Nos résultats montrent, pour la premièrefois, la possibilité de détecter empiriquement des cas phytoplanctoniques mixtes, au-delà dela dominance. Enfin, des pistes de recherche pour poursuivre la compréhension et le développementde PHYSAT sont proposées