MRI-based microthrombi detection in stroke with polydopamine iron oxide.

In acute ischemic stroke, even when successful recanalization is obtained, downstream microcirculation may still be obstructed by microvascular thrombosis, which is associated with compromised brain reperfusion and cognitive decline. Identifying these microthrombi through non-invasive methods remains challenging. We developed the PHySIOMIC (Polydopamine Hybridized Self-assembled Iron Oxide Mussel Inspired Clusters), a MRI-based contrast agent that unmasks these microthrombi. In a mouse model of thromboembolic ischemic stroke, our findings demonstrate that the PHySIOMIC generate a distinct hypointense signal on T2*-weighted MRI in the presence of microthrombi, that correlates with the lesion areas observed 24 hours post-stroke. Our microfluidic studies reveal the role of fibrinogen in the protein corona for the thrombosis targeting properties. Finally, we observe the biodegradation and biocompatibility of these particles. This work demonstrates that the PHySIOMIC particles offer an innovative and valuable tool for non-invasive in vivo diagnosis and monitoring of microthrombi, using MRI during ischemic stroke.

Generation and characterization of two new monoclonal antibodies produced by immunizing mice with plant fructans: New tools for immunolocalization of ß-(2 → 1) and ß-(2 → 6) fructans.

Fructans are water-soluble polymers of fructose in which fructose units are linked by ß-(2 â†’ 1) and/or ß-(2 â†’ 6) linkages. In plants, they are synthesized in the vacuole but have also been reported in the apoplastic sap under abiotic stress suggesting that they are involved in plasmalemma protection and in plant-microbial interactions. However, the lack of fructan-specific antibodies currently prevents further study of their role and the associated mechanisms of action, which could be elucidated thanks to their immunolocalization. We report the production of two monoclonal antibodies (named BTM9H2 and BTM15A6) using mice immunization with antigenic compounds prepared from a mixture of plant inulins and levans conjugated to serum albumin. Their specificity towards fructans with ß-(2 â†’ 1) and/or ß-(2 â†’ 6) linkage has been demonstrated by immuno-dot blot tests on a wide range of carbohydrates. The two mAbs were used for immunocytolocalization of fructans by epifluorescence microscopy in various plant species. Fructan epitopes were specifically detected in fructan-accumulating plants, inside cells as well as on the surface of root tips, confirming both extracellular and intracellular localizations. The two mAbs provide new tools to identify the mechanism of extracellular fructan secretion and explore the roles of fructans in stress resistance and plant-microorganism interactions.

Comparative analysis of response to treatments and molecular features of tumor-derived organoids versus cell lines and PDX derived from the same ovarian clear cell carcinoma.

BACKGROUND: In the era of personalized medicine, the establishment of preclinical models of cancer that faithfully recapitulate original tumors is essential to potentially guide clinical decisions. METHODS: We established 7 models [4 cell lines, 2 Patient-Derived Tumor Organoids (PDTO) and 1 Patient-Derived Xenograft (PDX)], all derived from the same Ovarian Clear Cell Carcinoma (OCCC). To determine the relevance of each of these models, comprehensive characterization was performed based on morphological, histological, and transcriptomic analyses as well as on the evaluation of their response to the treatments received by the patient. These results were compared to the clinical data. RESULTS: Only the PDX and PDTO models derived from the patient tumor were able to recapitulate the patient tumor heterogeneity. The patient was refractory to carboplatin, doxorubicin and gemcitabine, while tumor cell lines were sensitive to these treatments. In contrast, PDX and PDTO models displayed resistance to the 3 drugs. The transcriptomic analysis was consistent with these results since the models recapitulating faithfully the clinical response grouped together away from the other classical 2D cell culture models. We next investigated the potential of drugs that have not been used in the patient clinical management and we identified the HDAC inhibitor belinostat as a potential effective treatment based on PDTO response. CONCLUSIONS: PDX and PDTO appear to be the most relevant models, but only PDTO seem to present all the necessary prerequisites for predictive purposes and could constitute relevant tools for therapeutic decision support in the context of these particularly aggressive cancers refractory to conventional treatments.

Influence of nutrient enrichment on colonisation and photosynthetic parameters of hard substrate marine microphytobenthos.

This study aimed to assess the influence of nutrient enrichment on the development of microalgal biofilm on concrete and PVC cubes. Three mesocosms were utilized to create a nutrient gradient over a period of 28 days. Various parameters including biomass, photosynthetic activity, microtopography, and extracellular polymeric substances (EPS) were measured. Imaging PAM techniques were employed to obtain surface-wide data. Results revealed that nutrient availability had no significant impact on Chl a biomass and the maximum quantum efficiency of PSII (Fv/Fm). The photosynthetic capacity and efficiency were minimally affected by nutrient availability. Interestingly, the relationship between microphytobenthic (MPB) biomass and photosynthesis and surface rugosity exhibited distinct patterns. Negative reliefs showed a strong correlation with Fv/Fm, while no clear pattern emerged for biomass on rough concrete structures. Overall, our findings demonstrate that under conditions of heightened eutrophication, biofilm photosynthesis thrives in the fissures and crevasses of colonized structures regardless of nutrient levels. This investigation provides valuable insights into the interplay between nutrient availability and surface rugosity.

First isolation of Francisella halioticida strains from blue mussel (Mytilus edulis) in Normandy, France.

Mass mortality events affecting the blue mussels Mytilus edulis have been observed in France since 2014. The DNA of the bacterium Francisella halioticida, reported as pathogen of giant abalone (Haliotis gigantea) and Yesso scallop (Mizuhopecten yessoensis) has been detected recently in mussels from areas suffering mortalities. Isolation of this bacterium was attempted from individuals collected during mortality events. Identification was performed by 16S rRNA gene sequencing, real-time specific PCR and MALDI-ToF using spectra produced from the strain 8472-13A isolated from diseased Yesso scallop in Canada. Five isolates were identified as F. halioticida by real-time specific PCR and 16S rRNA sequencing. MALDI-ToF allowed the direct identification of four isolates (FR22a,b,c,d) which had 100% identity on the 16S rRNA gene with the known strains. On the other hand, one isolate (FR21) was not recognized by MALDI-ToF and had 99.9% identity on the 16S rRNA gene. The FR22 isolates showed difficult growth and required media optimization, which was not the case with the FR21 isolate. For these reasons, it was hypothesized that two type strains are present on French coasts, named FR21 and FR22. The FR21 isolate was selected for phenotypic analysis (growth curve, biochemical characteristics, electron microscopy), phylogenetic analysis and an experimental challenge. This isolate showed distinct differences compared to published F. halioticida strains, both at phenotypic and genotypic levels. Experimental infections of adult mussels led to 36% mortalities in 23 days following intramuscular injection with 3 × 107 CFU while a lower dose (3 × 103 CFU) did not lead to significant mortalities. In the context of this study, the strain FR21 was not virulent towards adult mussels.

Aluminium-based galvanic anode impacts the photosynthesis of microphytobenthos and supports the bioaccumulation of metals released.

Very few studies have looked at the potential biological effects of degradation products of galvanic anodes particularly on primary producers which are central to food webs in marine ecosystems. The galvanic anode cathodic protection system (GACP) is widely used to protect submerged metallic structures from corrosion. Aluminium (Al) and zinc (Zn) are the main constituents of galvanic anodes and are therefore released in the marine environment by oxidation process to form ions or oxy-hydroxides. The main objective of our study was to evaluate the effects of the metals released from an aluminium-based galvanic anode on microphytobenthos performance in term of biofilm growing through the analysis of photosynthetic parameters, the determination of chlorophyll and extracellular polymeric substances (EPS). The bioaccumulation of Al and Zn were measured in the microphytobenthic compartment collected at the surface of polyvinyl chloride (PVC) plates exposed during 13 days to seawaters enriched in different concentrations of metals released from dissolution of one anode. Determination of bioconcentration factors confirmed that the microphytobenthos has incorporated Al. A significative effect was observed on the Chl a concentration for the higher tested concentration ([Al] = 210.1 ± 60.2 µg L - 1; [Zn] = 20.2 ± 1.4 µg L - 1). The seawater exposed to the anode affected the MPB productivity (ETRIImax) with consequences on acclimatation light (Ek), absorption cross section of PSII (σPII), Fv/Fm and NPQ. Regarding the EPS production, the anode degradation presented an impact on high and low molecular weight of both carbohydrates and protein fractions of microphytobenthos suggesting that EPS play an essential role in sequestering metal contaminants to maintain the integrity of the biological membranes and the functionality of the cellular organelles. The accumulation of Al released by GACP in microphytobenthos cells could lead to physiologic problems in photosynthetic organisms.

Molecular approaches to uncover phage-lactic acid bacteria interactions in a model community simulating fermented beverages.

Food microbial diversity and fluxes during the fermentation processes are well studied whereas phages-bacteria interactions are still poorly described in the literature. This is especially true in fermented beverages, and especially in cider, which is an alcoholic fermented apple beverage. The transcriptomic and proteomic responses of the lactic acid bacterium (LAB) Liquorilactobacillus mali UCMA 16447 to a lytic infection by phage UCMA 21115, both isolated from cider, were investigated, in order to get a better understanding of phages-bacteria interactions in such fermented beverage. During phage infection, 122 and 215 genes were differentially expressed in L. mali UCMA 16447 strain at T15 and T60 respectively, when compared to the uninfected condition. The same trends were confirmed by the proteomic study, with a total of 28 differentially expressed proteins found at T60. Overall, genes encoding cellular functions, such as carbohydrate metabolism, translation, and signal transduction, were downregulated, while genes involved in nucleotide metabolism and in the control of DNA integrity were upregulated in response to phage infection. This work also highlighted that phage infection repressed many genes involved in bacterial cell motility, and affected glycolysis.

Internalization study of nanosized zeolite crystals in human glioblastoma cells.

While the use of nanozeolites for cancer treatment holds a great promise, it also requires a better understanding of the interaction between the zeolite nanoparticles and cancer cells and notably their internalization and biodistribution. It is particularly important in situation of hypoxia, a very common situations in aggressive cancers, which may change the energetic processes required for cellular uptake. Herein, we studied, in vitro, the kinetics of the internalization process and the intracellular localization of nanosized zeolite X (FAU-X) into glioblastoma cells. In normoxic conditions, scanning electron microscopy (SEM) showed a rapid cell membrane adhesion of zeolite nanoparticles (< 5 min following application in the cell medium), occurring before an energy-dependent uptake which appeared between 1 h and 4 h. Additionally, transmission electron microscopy (TEM) and flow cytometry analyzes, confirmed that the zeolite nanoparticles accumulate over time into the cytoplasm and were mostly located into vesicles visible at least up to 6 days. Interestingly, the uptake of zeolite nanoparticles was found to be dependent on oxygen concentration, i.e. an increase in internalization in severe hypoxia (0.2 % of O2) was observed. No toxicity of zeolite FAU-X nanoparticles was detected after 24 h and 72 h. The results clearly showed that the nanosized zeolites crystals were rapidly internalized via energy-requiring mechanism by cancer cells and even more in the hypoxic conditions. Once the zeolite nanoparticles were internalized into cells, they appeared to be safe and stable and therefore, they are envisioned to be used as carrier of various compounds to target cancer cells.

Tracking the immune response by MRI using biodegradable and ultrasensitive microprobes.

Molecular magnetic resonance imaging (MRI) holds great promise for diagnosis and therapeutic monitoring in a wide range of diseases. However, the low intrinsic sensitivity of MRI to detect exogenous contrast agents and the lack of biodegradable microprobes have prevented its clinical development. Here, we synthetized a contrast agent for molecular MRI based on a previously unknown mechanism of self-assembly of catechol-coated magnetite nanocrystals into microsized matrix-based particles. The resulting biodegradable microprobes (M3P for microsized matrix-based magnetic particles) carry up to 40,000 times higher amounts of superparamagnetic material than classically used nanoparticles while preserving favorable biocompatibility and excellent water dispersibility. After conjugation to monoclonal antibodies, targeted M3P display high sensitivity and specificity to detect inflammation in vivo in the brain, kidneys, and intestinal mucosa. The high payload of superparamagnetic material, excellent toxicity profile, short circulation half-life, and widespread reactivity of the M3P particles provides a promising platform for clinical translation of immuno-MRI.

Influence of infrastructure material composition and microtopography on marine biofilm growth and photobiology.

The impact of concrete composition and roughness on the formation of microalgal biofilms and their photobiology were studied on marine infrastructures presenting four different compositions combined with two degrees of roughness (rough and smooth). The structures were first inoculated with a natural microphytobenthic biofilm and immersed in sterilised seawater with a controlled photoperiod for six days. Photosynthetic activity was assessed with an imaging PAM-(Pulse Amplitude Modulated) fluorometer and microtopography was monitored in parallel with a 3-D camera. The results indicated that roughness had an impact on the biofilm biomass, its physiological status and its photosynthetic efficiency and capacity. The assessment of surface roughness indicated that negative reliefs were preferably colonised by MPB (microphytobenthic) cells with better photosynthetic performances. Moreover, MPB biofilms showed better photoacclimation in these microhabitats than on the positive and smooth reliefs. This study confirms the importance of microhabitat for biofilm formation and their photobiology.

Pseudomonas crudilactis sp. nov., isolated from raw milk in France.

Strains belonging to the Pseudomonas genus have been isolated worldwide from various biotic (humans, animals and plant tissues) and abiotic (food, soil, water and air) environments. Raw milk provides a favorable environment for the growth of a broad spectrum of microorganisms, including Pseudomonas. Here we present the description of Pseudomonas sp. UCMA 17988 isolated from raw milk, which was previously reported to produce new antimicrobial lipopeptides. MultiLocus Sequence Analysis of four housekeeping genes (16S rRNA, gyrB, rpoD and rpoB), whole genome sequence comparison (orthoANI value, original ANI value and dDDH value), microscopy, FAME analysis, and biochemical tests were performed. Digital DNA-DNA hybridization and average nucleotide identity values between strain UCMA 17988 and its closest relatives, P. helmanticensis CECT 8548T (46.9%, 92.07%) and P. baetica CECT 7720T (26.8%, 88.50%), rate well below the designed threshold for assigning prokaryotic strains to the same species. In conclusion, strain UCMA 17988 belongs to a novel species, for which the name Pseudomonas crudilactis sp. nov (type strain UCMA 17988T = DSM 109949T = LMG 31804T) is proposed.

Design of Non-Haemolytic Nanoemulsions for Intravenous Administration of Hydrophobic APIs.

Among advanced formulation strategies, nanoemulsions are considered useful drug-delivery systems allowing to improve the solubility and the bioavailability of lipophilic drugs. To select safe excipients for nanoemulsion formulation and to discard any haemolytic potential, an in vitro miniaturized test was performed on human whole blood. From haemolysis results obtained on eighteen of the most commonly used excipients, a medium chain triglyceride, a surfactant, and a solubilizer were selected for formulation assays. Based on a design of experiments and a ternary diagram, the feasibility of nanoemulsions was determined. The composition was defined to produce monodisperse nanodroplets with a diameter of either 50 or 120 nm, and their physicochemical properties were optimized to be suitable for intravenous administration. These nanoemulsions, stable over 21 days in storage conditions, were shown to be able to encapsulate with high encapsulation efficiency and high drug loading, up to 16% (w/w), two water practically insoluble drug models: ibuprofen and fenofibrate. Both drugs may be released according to a modulable profile in sink conditions. Such nanoemulsions appear as a very promising and attractive strategy for the efficient early preclinical development of hydrophobic drugs.

Phenotypic and proteomic approaches of the response to iron-limited condition in Staphylococcus lugdunensis.

BACKGROUND: Staphylococcus lugdunensis is a coagulase-negative Staphylococcus part of the commensal skin flora but emerge as an important opportunistic pathogen. Because iron limitation is a crucial stress during infectious process, we performed phenotypic study and compared proteomic profiles of this species incubated in absence and in presence of the iron chelator 2,2'-dipyridyl (DIP). RESULTS: No modification of cell morphology nor cell wall thickness were observed in presence of DIP. However iron-limitation condition promoted biofilm formation and reduced the ability to cope with oxidative stress (1 mM H2O2). In addition, S. lugdunensis N920143 cultured with DIP was significantly less virulent in the larvae of Galleria mellonella model of infection than that grown under standard conditions. We verified that these phenotypes were due to an iron limitation by complementation experiments with FeSO4. By mass spectrometry after trypsin digestion, we characterized the first iron-limitation stress proteome in S. lugdunensis. Among 1426 proteins identified, 349 polypeptides were differentially expressed. 222 were more and 127 less abundant in S. lugdunensis incubated in iron-limitation condition, and by RT-qPCR, some of the corresponding genes have been shown to be transcriptionally regulated. Our data revealed that proteins involved in iron metabolism and carriers were over-expressed, as well as several ABC transporters and polypeptides linked to cell wall metabolism. Conversely, enzymes playing a role in the oxidative stress response (especially catalase) were repressed. CONCLUSIONS: This phenotypic and global proteomic study allowed characterization of the response of S. lugdunensis to iron-limitation. We showed that iron-limitation promoted biofilm formation, but decrease the oxidative stress resistance that may, at least in part, explained the reduced virulence of S. lugdunensis observed under low iron condition.

Unexpected Cell Wall Alteration-Mediated Bactericidal Activity of the Antifungal Caspofungin against Vancomycin-Resistant Enterococcus faecium.

Enterococcus faecium has become a major opportunistic pathogen with the emergence of vancomycin-resistant enterococci (VRE). As part of the gut microbiota, they have to cope with numerous stresses, including effects of antibiotics and other xenobiotics, especially in patients hospitalized in intensive care units (ICUs) who receive many medications. The aim of this study was to investigate the impact of the most frequently prescribed xenobiotics for ICU patients on fitness, pathogenicity, and antimicrobial resistance of the vanB-positive E. faecium Aus0004 reference strain. Several phenotypic analyses were carried out, and we observed that caspofungin, an antifungal agent belonging to the family of echinocandins, had an important effect on E. faecium growth in vitro We confirmed this effect by electron microscopy and peptidoglycan analysis and showed that, even at a subinhibitory concentration (1/4× MIC, 8 mg/liter), caspofungin had an impact on cell wall organization, especially with respect to the abundance of some muropeptide precursors. By transcriptome sequencing (RNA-seq), it was also shown that around 20% of the transcriptome was altered in the presence of caspofungin, with 321 and 259 significantly upregulated and downregulated genes, respectively. Since the fungal target of caspofungin (i.e., ß-1,3-glucan synthase) was absent in bacteria, the mechanistic pathway of caspofungin activity was investigated. The repression of genes involved in the metabolism of pyruvate seemed to have a drastic impact on bacterial cell viability, while a decrease of glycerol metabolism could explain the conformational modifications of peptidoglycan. This is the first report of caspofungin antibacterial activity against E. faecium, highlighting the potential impact of nonantibiotic xenobiotics against bacterial pathogens.

Investigating Tunneling Nanotubes in Cancer Cells: Guidelines for Structural and Functional Studies through Cell Imaging.

By allowing insured communication between cancer cells themselves and with the neighboring stromal cells, tunneling nanotubes (TNTs) are involved in the multistep process of cancer development from tumorigenesis to the treatment resistance. However, despite their critical role in the biology of cancer, the study of the TNTs has been announced challenging due to not only the absence of a specific biomarker but also the fragile and transitory nature of their structure and the fact that they are hovering freely above the substratum. Here, we proposed to review guidelines to follow for studying the structure and functionality of TNTs in tumoral neuroendocrine cells (PC12) and nontumorigenic human bronchial epithelial cells (HBEC-3, H28). In particular, we reported how crucial is it (i) to consider the culture conditions (culture surface, cell density), (ii) to visualize the formation of TNTs in living cells (mechanisms of formation, 3D representation), and (iii) to identify the cytoskeleton components and the associated elements (categories, origin, tip, and formation/transport) in the TNTs. We also focused on the input of high-resolution cell imaging approaches including Stimulated Emission Depletion (STED) nanoscopy, Transmitted and Scanning Electron Microscopies (TEM and SEM). In addition, we underlined the important role of the organelles in the mechanisms of TNT formation and transfer between the cancer cells. Finally, new biological models for the identification of the TNTs between cancer cells and stromal cells (liquid air interface, ex vivo, in vivo) and the clinical considerations will also be discussed.

New landmarks in endonasal surgery: from nasal bone to anterior cribriform plate including branches of anterior ethmoidal artery and nerve and terminal nerve.

BACKGROUND: Despite the development of anterior skull base surgery, the anatomy of the nasal bone and anterior cribriform plate remains unclear. A recent study confirmed 2 distinct foramina in the anterior part of cribriform plate: the ethmoidal slit (ES) and the cribroethmoidal foramen (CF). The aim of this study was to specify their content, their anatomic relationship to the frontal sinus and skull base, and their potential value in skull base surgery. METHODS: Dissections were performed on 36 cadaver heads. Macro- and microscopic examinations were carried out. Microcomputed tomography scans contrasted with osmium were performed to identify vessels and nerves. Histology with neural, meningeal, or luteinizing hormone-releasing hormone immunomarkers was performed on the content of the foramina. Finally, endonasal surgical dissections were carried out. RESULTS: The ES and the CF were observed in all cases. They measured a mean of 4.2 and 1.6 mm, respectively. The ES contained dura mater, arachnoid tissues, lymphatics, and the terminal nerve. The CF contained the anterior ethmoidal nerve and artery. This foramen continued forward with the cribroethmoidal groove, which measured a mean of 2.5 mm. This groove was under the frontal sinus and in front of the skull base. We also described a "cribroethmoidal canal" and a "nasal bone foramen." CONCLUSION: The clinical applications of this new anatomic description concern both cribriform plate and frontal sinus surgeries. Identifying the terminal nerve passing through the ES is a step forward in understanding pheromone recognition in humans.

Histone Methylation Participates in Gene Expression Control during the Early Development of the Pacific Oyster Crassostrea gigas.

Histone methylation patterns are important epigenetic regulators of mammalian development, notably through stem cell identity maintenance by chromatin remodeling and transcriptional control of pluripotency genes. But, the implications of histone marks are poorly understood in distant groups outside vertebrates and ecdysozoan models. However, the development of the Pacific oyster Crassostrea gigas is under the strong epigenetic influence of DNA methylation, and Jumonji histone-demethylase orthologues are highly expressed during C. gigas early life. This suggests a physiological relevance of histone methylation regulation in oyster development, raising the question of functional conservation of this epigenetic pathway in lophotrochozoan. Quantification of histone methylation using fluorescent ELISAs during oyster early life indicated significant variations in monomethyl histone H3 lysine 4 (H3K4me), an overall decrease in H3K9 mono- and tri-methylations, and in H3K36 methylations, respectively, whereas no significant modification could be detected in H3K27 methylation. Early in vivo treatment with the JmjC-specific inhibitor Methylstat induced hypermethylation of all the examined histone H3 lysines and developmental alterations as revealed by scanning electronic microscopy. Using microarrays, we identified 376 genes that were differentially expressed under methylstat treatment, which expression patterns could discriminate between samples as indicated by principal component analysis. Furthermore, Gene Ontology revealed that these genes were related to processes potentially important for embryonic stages such as binding, cell differentiation and development. These results suggest an important physiological significance of histone methylation in the oyster embryonic and larval life, providing, to our knowledge, the first insights into epigenetic regulation by histone methylation in lophotrochozoan development.

Unusual extracellular appendages deployed by the model strain Pseudomonas fluorescens C7R12.

Pseudomonas fluorescens is considered to be a typical plant-associated saprophytic bacterium with no pathogenic potential. Indeed, some P. fluorescens strains are well-known rhizobacteria that promote plant growth by direct stimulation, by preventing the deleterious effects of pathogens, or both. Pseudomonas fluorescens C7R12 is a rhizosphere-competent strain that is effective as a biocontrol agent and promotes plant growth and arbuscular mycorrhization. This strain has been studied in detail, but no visual evidence has ever been obtained for extracellular structures potentially involved in its remarkable fitness and biocontrol performances. On transmission electron microscopy of negatively stained C7R12 cells, we observed the following appendages: multiple polar flagella, an inducible putative type three secretion system typical of phytopathogenic Pseudomonas syringae strains and densely bundled fimbria-like appendages forming a broad fractal-like dendritic network around single cells and microcolonies. The deployment of one or other of these elements on the bacterial surface depends on the composition and affinity for the water of the microenvironment. The existence, within this single strain, of machineries known to be involved in motility, chemotaxis, hypersensitive response, cellular adhesion and biofilm formation, may partly explain the strong interactions of strain C7R12 with plants and associated microflora in addition to the type three secretion system previously shown to be implied in mycorrhizae promotion.

Identification of a novel splice site mutation in the SERAC1 gene responsible for the MEGDHEL syndrome.

BACKGROUND: MEGDHEL is an autosomal recessive syndrome defined as 3-MEthylGlutaconic aciduria (3-MGA) with Deafness, Hepatopathy, Encephalopathy, and Leigh-like syndrome on magnetic resonance imaging, due to mutations in the SERAC1 (Serine Active Site Containing 1) gene, which plays a role in the mitochondrial cardiolipin metabolism. METHODS: We report the case of a young patient who presented with a convulsive encephalopathy, 3-methylglutaconic aciduria, deafness, and bilateral T2 hypersignals of the putamen and the thalami, who passed away at 8 years of age. RESULTS: Analysis of nuclear genes using an ampliSeq™ targeted custom panel disclosed two compound heterozygous variants in the SERAC1 gene: a nonsense substitution in exon 4, c.202C>T, resulting in a premature stop codon (p.Arg68*), and a novel variant at a canonical splicing site upstream exon 4 (c.129-1G>C). mRNAs sequencing from the fibroblasts of the patient showed that the splice site variant resulted in exon 3 skipping without frameshift while Western blot experiments showed the absence of SERAC1 expression compared to controls and abnormal filipin staining. CONCLUSION: We showed that the loss of the putative transmembrane domain of SERAC1, due to a novel splice site variant, impairs the protein expression and is responsible for the MEGDHEL syndrome.

Oenococcus sicerae sp. nov., isolated from French cider.

Two Gram-stain-positive, small ellipsoidal cocci, non-motile, oxidase- and catalase-negative, and facultative anaerobic strains (UCMA15228T and UCMA17102) were isolated in France, from fermented apple juices (ciders). The 16S rRNA gene sequence was identical between the two isolates and showed 97 % similarity with respect to the closest related species Oenococcus oeni and O. kitaharae. Therefore, the two isolates were classified within the genus Oenococcus. The phylogeny based on the pheS gene sequences also confirmed the position of the new taxon. DNA-DNA hybridizations based on in silico genome-to-genome comparisons (GGDC) and Average Nucleotide Identity (ANI) values, as well as species-specific PCR, validated the novelty of the taxon. Various phenotypic characteristics such as the optimum temperature and pH for growth, the ability to metabolise sugars, the aptitude to perform the malolactic fermentation, and the resistance to ethanol and NaCl, revealed that the two strains are distinguishable from the other members of the Oenococcus genus. The combined genotypic and phenotypic data support the classification of strains UCMA15228T and UCMA17102 into a novel species of Oenococcus, for which the name O. sicerae sp. nov. is proposed. The type strain is UCMA15228T (=DSM107163T=CIRM-BIA2288T).