Phosphatidylcholine-deficient suppressor mutant of Sinorhizobium meliloti, altered in fatty acid synthesis, partially recovers nodulation ability in symbiosis with alfalfa (Medicago sativa).

Rhizobial phosphatidylcholine (PC) is thought to be a critical phospholipid for the symbiotic relationship between rhizobia and legume host plants. A PC-deficient mutant of Sinorhizobium meliloti overproduces succinoglycan, is unable to swim, and lacks the ability to form nodules on alfalfa (Medicago sativa) host roots. Suppressor mutants had been obtained which did not overproduce succinoglycan and regained the ability to swim. Previously, we showed that point mutations leading to altered ExoS proteins can reverse the succinoglycan and swimming phenotypes of a PC-deficient mutant. Here, we report that other point mutations leading to altered ExoS, ChvI, FabA, or RpoH1 proteins also revert the succinoglycan and swimming phenotypes of PC-deficient mutants. Notably, the suppressor mutants also restore the ability to form nodule organs on alfalfa roots. However, nodules generated by these suppressor mutants express only low levels of an early nodulin, do not induce leghemoglobin transcript accumulation, thus remain white, and are unable to fix nitrogen. Among these suppressor mutants, we detected a reduced function mutant of the 3-hydoxydecanoyl-acyl carrier protein dehydratase FabA that produces reduced amounts of unsaturated and increased amounts of shorter chain fatty acids. This alteration of fatty acid composition probably affects lipid packing thereby partially compensating for the previous loss of PC and contributing to the restoration of membrane homeostasis.

Brain injury drives optic glioma formation through neuron-glia signaling.

Tissue injury and tumorigenesis share many cellular and molecular features, including immune cell (T cells, monocytes) infiltration and inflammatory factor (cytokines, chemokines) elaboration. Their common pathobiology raises the intriguing possibility that brain injury could create a tissue microenvironment permissive for tumor formation. Leveraging several murine models of the Neurofibromatosis type 1 (NF1) cancer predisposition syndrome and two experimental methods of brain injury, we demonstrate that both optic nerve crush and diffuse traumatic brain injury induce optic glioma (OPG) formation in mice harboring Nf1-deficient preneoplastic progenitors. We further elucidate the underlying molecular and cellular mechanisms, whereby glutamate released from damaged neurons stimulates IL-1ß release by oligodendrocytes to induce microglia expression of Ccl5, a growth factor critical for Nf1-OPG formation. Interruption of this cellular circuit using glutamate receptor, IL-1ß or Ccl5 inhibitors abrogates injury-induced glioma progression, thus establishing a causative relationship between injury and tumorigenesis.

Membrane lipid composition defines membrane protein spectrum.

In addition to glycerophospholipids, bacterial membranes often include amino acid-containing acyloxyacyl lipids. The functional implications of these aminolipids are largely unknown. However, a recent study by Stirrup et al. expands our understanding and shows that they are major determinants for membrane properties and the relative abundance of distinct membrane proteins in bacterial membranes.

TFIIIC as a Potential Epigenetic Modulator of Histone Acetylation in Human Stem Cells.

Regulation of histone acetylation dictates patterns of gene expression and hence cell identity. Due to their clinical relevance in cancer biology, understanding how human embryonic stem cells (hESCs) regulate their genomic patterns of histone acetylation is critical, but it remains largely to be investigated. Here, we provide evidence that acetylation of histone H3 lysine-18 (H3K18ac) and lysine-27 (H3K27ac) is only partially established by p300 in stem cells, while it represents the main histone acetyltransferase (HAT) for these marks in somatic cells. Our analysis reveals that whereas p300 marginally associated with H3K18ac and H3K27ac in hESCs, it largely overlapped with these histone marks upon differentiation. Interestingly, we show that H3K18ac is found at "stemness" genes enriched in RNA polymerase III transcription factor C (TFIIIC) in hESCs, whilst lacking p300. Moreover, TFIIIC was also found in the vicinity of genes involved in neuronal biology, although devoid of H3K18ac. Our data suggest a more complex pattern of HATs responsible for histone acetylations in hESCs than previously considered, suggesting a putative role for H3K18ac and TFIIIC in regulating "stemness" genes as well as genes associated with neuronal differentiation of hESCs. The results break ground for possible new paradigms for genome acetylation in hESCs that could lead to new avenues for therapeutic intervention in cancer and developmental diseases.

O ensino da matemática para estudantes com paralisia cerebral: ações que contribuem para a inclusão de todos / Teaching mathematics to students with cerebral palsy: actions that contribute to the inclusion of all

RESUMO A origem deste artigo é uma tese que propôs categorizar ações para possibilitar um ensino da Matemática mais eficaz para estudantes com paralisia cerebral (PC). O objetivo deste texto é apresentar a categorização de ações que contribuam com uma proposta de ensino voltada a todos. As ações fundamentam-se em atitudes acolhedoras por parte de professores e estudantes, adaptação de materiais ou uso de recursos que prezem pela inclusão de pessoas com PC. Os participantes da pesquisa foram 13 professores de Matemática e 11 estudantes com PC, distribuídos em cinco escolas de Educação Básica. Suas falas, transcritas após a realização de uma entrevista semiestruturada, foram analisadas por meio da Análise Textual Discursiva, cujos excertos são articulados com um referencial teórico baseado nas Neurociências, na Educação Matemática e na Educação Inclusiva. Na conclusão, é exposta a necessidade de a escola oferecer um ambiente adequado para a aprendizagem, estruturado por meio do estímulo e da acolhida às diferenças. Para isso, utiliza-se da linguagem corporal e gestual como estratégia de comunicação, bem como da aplicação, em sala de aula ou em sala especializada, de materiais manipulativos ou provenientes de tecnologia informatizada que supram as barreiras impostas pela deficiência.

ABSTRACT The origin of this article is a thesis that proposed to categorize actions to enable a more effective teaching of Mathematics for students with cerebral palsy (CP). The purpose of this text is to present the categorization of actions that contribute to a teaching proposal aimed at all. The actions are based on welcoming attitudes on the part of teachers and students, adaptation of materials or the use of resources that value the inclusion of people with PC. The research participants were 13 Mathematics teachers and 11 students with PC, distributed in five Basic Education schools. Their speeches, transcribed after conducting a semi-structured interview, were analyzed using the Discursive Textual Analysis, whose excerpts are articulated with a theoretical framework based on Neurosciences, Mathematics Education and Inclusive Education. In conclusion, the need for the school to offer an adequate environment for learning is exposed, structured through stimulation and the welcoming of differences. For this, body language and gestures are used as a communication strategy, as well as the application, in the classroom or specialized room, of manipulative materials or those from computerized technology that overcome the barriers imposed by the disability.

Specialized acyl carrier protein used by serine palmitoyltransferase to synthesize sphingolipids in Rhodobacteria.

Serine palmitoyltransferase (SPT) catalyzes the first and committed step in sphingolipid biosynthesis condensating L-serine and acyl-CoA to form 3-oxo-sphinganine. Whenever the structural gene for SPT is present in genomes of Rhodobacteria (α-, ß-, and γ-Proteobacteria), it co-occurs with genes coding for a putative acyl carrier protein (ACP) and a putative acyl-CoA synthetase (ACS). In the α-proteobacterium Caulobacter crescentus, CC_1162 encodes an SPT, whereas CC_1163 and CC_1165 encode the putative ACP and ACS, respectively, and all three genes are known to be required for the formation of the sphingolipid intermediate 3-oxo-sphinganine. Here we show that the putative ACP possesses a 4'-phosphopantetheine prosthetic group, is selectively acylated by the putative ACS and therefore is a specialized ACP (AcpR) required for sphingolipid biosynthesis in Rhodobacteria. The putative ACS is unable to acylate coenzyme A or housekeeping ACPs, but acylates specifically AcpR. Therefore, it is a specialized acyl-ACP synthetase (AasR). SPTs from C. crescentus, Escherichia coli B, or Sphingomonas wittichii use preferentially acyl-AcpR as thioester substrate for 3-oxo-sphinganine synthesis. Whereas acyl-AcpR from C. crescentus is a good substrate for SPTs from distinct Rhodobacteria, acylation of a specific AcpR is achieved by the cognate AasR from the same bacterium. Rhodobacteria might use this more complex way of 3-oxo-sphinganine formation in order to direct free fatty acids toward sphingolipid biosynthesis.

A set of accessible enhancers enables the initial response of breast cancer cells to physiological progestin concentrations.

Here, we report that in T47D breast cancer cells 50 pM progestin is sufficient to activate cell cycle entry and the progesterone gene expression program. At this concentration, equivalent to the progesterone blood levels found around the menopause, progesterone receptor (PR) binds only to 2800 genomic sites, which are accessible to ATAC cleavage prior to hormone exposure. These highly accessible sites (HAs) are surrounded by well-organized nucleosomes and exhibit breast enhancer features, including estrogen receptor alpha (ERα), higher FOXA1 and BRD4 (bromodomain containing 4) occupancy. Although HAs are enriched in RAD21 and CTCF, PR binding is the driving force for the most robust interactions with hormone-regulated genes. HAs show higher frequency of 3D contacts among themselves than with other PR binding sites, indicating colocalization in similar compartments. Gene regulation via HAs is independent of classical coregulators and ATP-activated remodelers, relying mainly on MAP kinase activation that enables PR nuclear engagement. HAs are also preferentially occupied by PR and ERα in breast cancer xenografts derived from MCF-7 cells as well as from patients, indicating their potential usefulness as targets for therapeutic intervention.

ExoS/ChvI Two-Component Signal-Transduction System Activated in the Absence of Bacterial Phosphatidylcholine.

Sinorhizobium meliloti contains the negatively charged phosphatidylglycerol and cardiolipin as well as the zwitterionic phosphatidylethanolamine (PE) and phosphatidylcholine (PC) as major membrane phospholipids. In previous studies we had isolated S. meliloti mutants that lack PE or PC. Although mutants deficient in PE are able to form nitrogen-fixing nodules on alfalfa host plants, mutants lacking PC cannot sustain development of any nodules on host roots. Transcript profiles of mutants unable to form PE or PC are distinct; they differ from each other and they are different from the wild type profile. For example, a PC-deficient mutant of S. meliloti shows an increase of transcripts that encode enzymes required for succinoglycan biosynthesis and a decrease of transcripts required for flagellum formation. Indeed, a PC-deficient mutant is unable to swim and overproduces succinoglycan. Some suppressor mutants, that regain swimming and form normal levels of succinoglycan, are altered in the ExoS sensor. Our findings suggest that the lack of PC in the sinorhizobial membrane activates the ExoS/ChvI two-component regulatory system. ExoS/ChvI constitute a molecular switch in S. meliloti for changing from a free-living to a symbiotic life style. The periplasmic repressor protein ExoR controls ExoS/ChvI function and it is thought that proteolytic ExoR degradation would relieve repression of ExoS/ChvI thereby switching on this system. However, as ExoR levels are similar in wild type, PC-deficient mutant and suppressor mutants, we propose that lack of PC in the bacterial membrane provokes directly a conformational change of the ExoS sensor and thereby activation of the ExoS/ChvI two-component system.

Rhizobial Volatiles: Potential New Players in the Complex Interkingdom Signaling With Legumes.

Bacteria release a wide range of volatile compounds that play important roles in intermicrobial and interkingdom communication. Volatile metabolites emitted by rhizobacteria can promote plant growth and increase plant resistance to both biotic and abiotic stresses. Rhizobia establish beneficial nitrogen-fixing symbiosis with legume plants in a process starting with a chemical dialog in the rhizosphere involving various diffusible compounds. Despite being one of the most studied plant-interacting microorganisms, very little is known about volatile compounds produced by rhizobia and their biological/ecological role. Evidence indicates that plants can perceive and respond to volatiles emitted by rhizobia. In this perspective, we present recent data that open the possibility that rhizobial volatile compounds have a role in symbiotic interactions with legumes and discuss future directions that could shed light onto this area of investigation.

Five structural genes required for ceramide synthesis in Caulobacter and for bacterial survival.

Sphingolipids are essential and common membrane components in eukaryotic organisms, participating in many important cellular functions. Only a few bacteria are thought to harbour sphingolipids in their membranes, among them the well-studied α-proteobacterium Caulobacter crescentus, a model organism for asymmetric cell division and cellular differentiation. Here, we report that C. crescentus wild type produces several molecular species of dihydroceramides, which are not produced in a mutant lacking the structural gene for serine palmitoyltransferase (spt). Whereas growth of a spt-deficient mutant and wild type are indistinguishable during the exponential phase of growth, survival of the spt-deficient mutant is much reduced, in comparison with wild type, during stationary phase of growth, especially at elevated temperatures. The structural gene for spt is located within a genomic cluster, comprising another 16 genes and which, like spt, are important for fitness of C. crescentus. Mutants deficient in genes linked to spt by high cofitness were unable to produce dihydroceramide or to survive in stationary phase of growth at elevated temperatures. At least five structural genes are required for dihydroceramide biosynthesis in C. crescentus and sphingolipid biosynthesis is needed for survival of this bacterium and the integrity of its outer membrane.

Ripening-related cell wall modifications in olive (Olea europaea L.) fruit: A survey of nine genotypes.

The production of olive (Olea europaea L.) is very important economically in many areas of the world, and particularly in countries around the Mediterranean basin. Ripening-associated modifications in cell wall composition and structure of fruits play an important role in attributes like firmness or susceptibility to infestations, rots and mechanical damage, but limited information on these aspects is currently available for olive. In this work, cell wall metabolism was studied in fruits from nine olive cultivars ('Arbequina', 'Argudell', 'Empeltre', 'Farga', 'Manzanilla', 'Marfil', 'Morrut', 'Picual' and 'Sevillenca') picked at three maturity stages (green, turning and ripe). Yields of alcohol-insoluble residue (AIR) recovered from fruits, as well as calcium content in fruit pericarp, decreased along ripening. Cultivar-specific diversity was observed in time-course change patterns of enzyme activity, particularly for those acting on arabinosyl- and galactosyl-rich pectin side chains. Even so, fruit firmness levels were associated to higher pectin methylesterase (PME) activity and calcium contents. In turn, fruit firmness correlated inversely with ascorbate content and with α-l-arabinofuranosidase (AFase) and ß-galactosidase (ß-Gal) activities, resulting in preferential loss of neutral sugars from cell wall polymers.

Compositional, structural and functional cuticle analysis of Prunus laurocerasus L. sheds light on cuticular barrier plasticity.

Barrier properties of the hydrophobic plant cuticle depend on its physicochemical composition. The cuticular compounds vary considerably among plant species but also among organs and tissues of the same plant and throughout developmental stages. As yet, these intraspecific modifications at the cuticular wax and cutin level are only rarely examined. Attempting to further elucidate cuticle profiles, we analysed the adaxial and abaxial surfaces of the sclerophyllous leaf and three developmental stages of the drupe fruit of Prunus laurocerasus, an evergreen model plant native to temperate regions. According to gas chromatographic analyses, the cuticular waxes contained primarily pentacyclic triterpenoids dominated by ursolic acid, whereas the cutin biopolyester mainly consisted of 9/10,ω-dihydroxy hexadecanoic acid. Distinct organ- and side-specific patterns were found for cuticular lipid loads, compositions and carbon chain length distributions. Compositional variations led to different structural and functional barrier properties of the plant cuticle, which were investigated further microscopically, infrared spectroscopically and gravimetrically. The minimum water conductance was highlighted at 1 × 10-5 m s-1 for the perennial, hypostomatous P. laurocerasus leaf and at 8 × 10-5 m s-1 for the few-month-living, stomatous fruit suggesting organ-specific cuticular barrier demands.

Paraburkholderia lycopersici sp. nov., a nitrogen-fixing species isolated from rhizoplane of Lycopersicon esculentum Mill. var. Saladette in Mexico.

A survey of our in-house bacterial collection identified a group of six strains isolated from the tomato rhizoplane that possessed 16S rRNA gene sequences with 98.2% sequence similarity to Paraburkholderia pallida, suggesting that these strains represented a novel species. Multilocus sequence analysis using gltB, lepA and recA gene sequences showed the clustering of the strains and the BOX-PCR patterns were similar among these strains. The average nucleotide identity and the DNA-DNA virtual hybridization of strain TNe-862T was <89% and <34%, respectively, to the genomes of any sequenced Paraburkholderia species. The genome of strain TNe-862T possessed all the genes necessary for nitrogen fixation and biosynthesis of indoleacetic acid and antimicrobials terpenes, phosphonates and bacteriocins. It also contained genes for metal resistance, xenobiotic degradation, and hydrolytic enzymes such as a putative chitinase and isoamylase. Even though the strain contained potential genes for degradation of cellulose and starch, the bacterium was unable to utilize these substrates in culture medium. The genome encoded flagella and pili as well as multiple chemotaxis systems. In addition, genes encoding for the type I, II, IV, V and VI secretion systems were also present. The strains grow up to 42°C and 5% NaCl. The optimum growth pH was 8. The major cellular fatty acids were C16:0 and C18:1 ω7c. Based on this polyphasic analysis, these strains represent a novel species in the genus Paraburkholderia, for which the name Paraburkholderia lycopersici sp. nov. is proposed. The type strain is TNe-862T (=LMG 26415T=CIP 110323T).

Accuracy of ADC ratio in discriminating true and false positives in multiparametric prostatic MRI.

PURPOSE: Our goal was to evaluate the usefulness of apparent diffusion coefficient (ADC) ratios in discriminating true from false positives in multiparametric (mp) prostate MRI in clinical practice. METHODS: We retrospectively evaluated 98 prostate lesions in a series of 73 patients who had undergone prostate mpMRI and standard 12-core prostatic biopsy in our institution from 2016 to 2018. Two experienced radiologists performed double blind ADC value quantifications of both MRI-identified lesions and apparently benign contralateral prostatic parenchyma in a circular region of interest (ROI) of ∼10 mm2. The ratios between the mean values of both measurements (i.e., ADC ratio mean) and between the minimum value of the lesion and the maximum value of the benign parenchyma (i.e., ADC ratio min-max) were automatically calculated. The malignancy of all lesions was determined through biopsy according to Gleason score (GS ≥ 6) and localization. RESULTS: For Reader 1, the area under the ROC curve (AUC) of ADC ratio mean and ADC ratio min-max were 0.72 and 0.67, respectively, whereas for Reader 2 these values were 0.74 and 0.71, respectively. The best cut-off values for ADC ratio means were ≥ 0.5 (Reader 1) and ≥ 0.6 (Reader 2), with a sensitivity of 76.3 % and 84.2 % and a specificity of 51.7 % and 50 %, respectively. Moreover, based on a threshold of 0.6, no clinically significant prostate cancer (csPCa) was missed by Reader 1, while only one went unnoticed by Reader 2. CONCLUSION: The ADC ratio is a useful and moderately accurate complementary tool to diagnose prostate cancer in the mp-MRI.

Role of Sinorhizobium meliloti and Escherichia coli Long-Chain Acyl-CoA Synthetase FadD in Long-Term Survival.

FadD is an acyl-coenzyme A (CoA) synthetase specific for long-chain fatty acids (LCFA). Strains mutated in fadD cannot produce acyl-CoA and thus cannot grow on exogenous LCFA as the sole carbon source. Mutants in the fadD (smc02162) of Sinorhizobium meliloti are unable to grow on oleate as the sole carbon source and present an increased surface motility and accumulation of free fatty acids at the entry of the stationary phase of growth. In this study, we found that constitutive expression of the closest FadD homologues of S. meliloti, encoded by sma0150 and smb20650, could not revert any of the mutant phenotypes. In contrast, the expression of Escherichia coli fadD could restore the same functions as S. meliloti fadD. Previously, we demonstrated that FadD is required for the degradation of endogenous fatty acids released from membrane lipids. Here, we show that absence of a functional fadD provokes a significant loss of viability in cultures of E. coli and of S. meliloti in the stationary phase, demonstrating a crucial role of fatty acid degradation in survival capacity.