RESUMO
Transcriptomic studies have revealed that fungal pathogens of plants activate the expression of numerous biosynthetic gene clusters (BGC) exclusively when in presence of a living host plant. The identification and structural elucidation of the corresponding secondary metabolites remain challenging. The aim was to develop a polycistronic system for heterologous expression of fungal BGCs in Saccharomyces cerevisiae. Here we adapted a polycistronic vector for efficient, seamless and cost-effective cloning of biosynthetic genes using in vivo assembly (also called transformation-assisted recombination) directly in Escherichia coli followed by heterologous expression in S. cerevisiae. Two vectors were generated with different auto-inducible yeast promoters and selection markers. The effectiveness of these vectors was validated with fluorescent proteins. As a proof-of-principle, we applied our approach to the Colletochlorin family of molecules. These polyketide secondary metabolites were known from the phytopathogenic fungus Colletotrichum higginsianum but had never been linked to their biosynthetic genes. Considering the requirement for a halogenase, and by applying comparative genomics, we identified a BGC putatively involved in the biosynthesis of Colletochlorins in C. higginsianum. Following the expression of those genes in S. cerevisiae, we could identify the presence of the precursor Orsellinic acid, Colletochlorins and their non-chlorinated counterparts, the Colletorins. In conclusion, the polycistronic vectors described herein were adapted for the host S. cerevisiae and allowed to link the Colletochlorin compound family to their corresponding biosynthetic genes. This system will now enable the production and purification of infection-specific secondary metabolites of fungal phytopathogens. More widely, this system could be applied to any fungal BGC of interest.
Assuntos
Família Multigênica , Saccharomyces cerevisiae , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Regiões Promotoras Genéticas , Família Multigênica/genéticaRESUMO
Reelin, a large secreted glycoprotein, plays an important role in neuronal migration during brain development. The C-terminal region (CTR) of Reelin is involved in the efficient activation of downstream signaling and its loss leads to abnormal hippocampal layer formation. However, the molecular mechanism by which Reelin CTR regulates hippocampal development remains unknown. Here, we showed that the migration of late-born, but not early-born, neurons is impaired in the knock-in mice in which Reelin CTR is deleted (ΔC-KI mice). The phosphorylation of cofilin, an actin-depolymerizing protein, was remarkably decreased in the hippocampus of the ΔC-KI mice. Exogenous expression of pseudo-phosphorylated cofilin rescued the ectopic positioning of neurons in the hippocampus of ΔC-KI mice. These results suggest that Reelin CTR is required for the migration of late-born neurons in the hippocampus and that this event involves appropriate phosphorylation of cofilin.
Assuntos
Fatores de Despolimerização de Actina , Proteínas da Matriz Extracelular , Proteína Reelina , Animais , Camundongos , Fatores de Despolimerização de Actina/metabolismo , Moléculas de Adesão Celular Neuronais/genética , Moléculas de Adesão Celular Neuronais/metabolismo , Proteínas da Matriz Extracelular/genética , Proteínas da Matriz Extracelular/metabolismo , Hipocampo/metabolismo , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismo , Neurônios/metabolismo , Fosforilação , Serina Endopeptidases/genética , Serina Endopeptidases/metabolismo , Proteína Reelina/metabolismoRESUMO
Septoria tritici blotch (STB), caused by the fungus Zymoseptoria tritici, is among the most threatening wheat diseases in Europe. Genetic resistance remains one of the main environmentally sustainable strategies to efficiently control STB. However, the molecular and physiological mechanisms underlying resistance are still unknown, limiting the implementation of knowledge-driven management strategies. Among the 22 known major resistance genes (Stb), the recently cloned Stb16q gene encodes a cysteine-rich receptor-like kinase conferring a full broad-spectrum resistance against Z. tritici. Here, we showed that an avirulent Z. tritici inoculated on Stb16q quasi near isogenic lines (NILs) either by infiltration into leaf tissues or by brush inoculation of wounded tissues partially bypasses Stb16q-mediated resistance. To understand this bypass, we monitored the infection of GFP-labeled avirulent and virulent isolates on Stb16q NILs, from germination to pycnidia formation. This quantitative cytological analysis revealed that 95% of the penetration attempts were unsuccessful in the Stb16q incompatible interaction, while almost all succeeded in compatible interactions. Infectious hyphae resulting from the few successful penetration events in the Stb16q incompatible interaction were arrested in the sub-stomatal cavity of the primary-infected stomata. These results indicate that Stb16q-mediated resistance mainly blocks the avirulent isolate during its stomatal penetration into wheat tissue. Analyses of stomatal aperture of the Stb16q NILs during infection revealed that Stb16q triggers a temporary stomatal closure in response to an avirulent isolate. Finally, we showed that infiltrating avirulent isolates into leaves of the Stb6 and Stb9 NILs also partially bypasses resistances, suggesting that arrest during stomatal penetration might be a common major mechanism for Stb-mediated resistances.
RESUMO
BACKGROUND: The vascular system of plants consists of two main tissue types, xylem and phloem. These tissues are organized into vascular bundles that are arranged into a complex network running through the plant that is essential for the viability of land plants. Despite their obvious importance, the genes involved in the organization of vascular tissues remain poorly understood in grasses. RESULTS: We studied in detail the vascular network in stems from the model grass Brachypodium distachyon (Brachypodium) and identified a large set of genes differentially expressed in vascular bundles versus parenchyma tissues. To decipher the underlying molecular mechanisms of vascularization in grasses, we conducted a forward genetic screen for abnormal vasculature. We identified a mutation that severely affected the organization of vascular tissues. This mutant displayed defects in anastomosis of the vascular network and uncommon amphivasal vascular bundles. The causal mutation is a premature stop codon in ERECTA, a LRR receptor-like serine/threonine-protein kinase. Mutations in this gene are pleiotropic indicating that it serves multiple roles during plant development. This mutant also displayed changes in cell wall composition, gene expression and hormone homeostasis. CONCLUSION: In summary, ERECTA has a pleiotropic role in Brachypodium. We propose a major role of ERECTA in vasculature anastomosis and vascular tissue organization in Brachypodium.
Assuntos
Brachypodium/genética , Floema/crescimento & desenvolvimento , Proteínas de Plantas/genética , Proteínas Serina-Treonina Quinases/genética , Receptores de Superfície Celular/genética , Xilema/crescimento & desenvolvimento , Brachypodium/crescimento & desenvolvimento , Brachypodium/metabolismo , Floema/genética , Proteínas de Plantas/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Receptores de Superfície Celular/metabolismo , Xilema/genéticaRESUMO
The spatial organization in the cell nucleus is tightly linked to genome functions such as gene regulation. Similarly, specific spatial arrangements of biological components such as macromolecular complexes, organelles and cells are involved in many biological functions. Spatial interactions among elementary components of biological systems define their relative positioning and are key determinants of spatial patterns. However, biological variability and the lack of appropriate spatial statistical methods and models limit our current ability to analyze these interactions. Here, we developed a framework to dissect spatial interactions and organization principles by combining unbiased statistical tests, multiple spatial descriptors and new spatial models. We used plant constitutive heterochromatin as a model system to demonstrate the potential of our framework. Our results challenge the common view of a peripheral organization of chromocenters, showing that chromocenters are arranged along both radial and lateral directions in the nuclear space and obey a multiscale organization with scale-dependent antagonistic effects. The proposed generic framework will be useful to identify determinants of spatial organizations and to question their interplay with biological functions.
Assuntos
Arabidopsis/metabolismo , Heterocromatina/metabolismo , Modelos Biológicos , Arabidopsis/genética , Heterocromatina/genéticaRESUMO
Pointed gourd (Trichosanthes dioica Roxb.) (2n = 2x = 22) is a dioecious cucurbit vegetable and green fruit that is edible after cooking. Consumers prefer to consume seedless or less-seeded fruit because seeds are unpalatable due to their hard coats. Therefore, the cross compatibility between the diploid and induced tetraploid will be helpful for seedless or less-seeded fruit production. Thus, the present study was conducted using mature seeds that were immersed in 0.05%, 0.1%, and 0.5% colchicine for 24, 48, and 72 h to induce tetraploids. These tetraploids were used as parents (male or female) in the inter-ploidy and intra-ploidy crosses. A flow cytometric analysis confirmed the induction of three tetraploids at 0.5% colchicine for 48 and 72 h soaking periods. Among these, two (2) females and one (1) male were differentiated after flower initiation. Crossing between the tetraploid's maternal and diploid paternal parent (4x × 2x), which were revealed to be compatible, resulted in a similar fruit set rate and shape as those of the diploid. In addition, a seed number of 4x × 2x produced fruits that were drastically reduced to 1.8 seeds per fruit, whereas the natural diploid fruits had 26.4 seeds per fruit. These findings suggest that colchicine-induced tetraploid females are important genetic resources for less-seeded fruit production. The genetic stability of tetraploid clones can easily and effectively be maintained by vine cutting for advanced uses.
RESUMO
We investigated effects of isoflurane and sevoflurane on sparfloxacin-induced QT-interval prolongation in guinea pigs under the monitoring of electrocardiogram and monophasic action potential (MAP), which was compared with those of halothane or non-inhaled anesthetics ketamine/xylazine. Intravenous administration of sparfloxacin at 3 and 10 mg/kg prolonged the QT interval and MAP duration together with bradycardic action under 4 different anesthetic conditions. The order of extent of prolongation of corrected QT interval after the administration of sparfloxacin was isoflurane ≈ sevoflurane ≈ halothane >> ketamine/xylazine, whereas that of the MAP90 at a pacing cycle length of 300 ms was halothane ≥ isoflurane ≈ sevoflurane >> ketamine/xylazine. These results suggest that isoflurane and sevoflurane as well as halothane could sensitize the heart to sparfloxacin-induced QT interval prolongation in guinea pigs.
Assuntos
Anestésicos Inalatórios/efeitos adversos , Isoflurano/efeitos adversos , Síndrome do QT Longo/induzido quimicamente , Sevoflurano/efeitos adversos , Potenciais de Ação/efeitos dos fármacos , Animais , Eletrocardiografia/efeitos dos fármacos , Fluoroquinolonas/administração & dosagem , Fluoroquinolonas/efeitos adversos , Cobaias , Halotano/efeitos adversos , Síndrome do QT Longo/fisiopatologia , MasculinoRESUMO
BACKGROUND: Plant protoplasts are basic plant cells units in which the pecto-cellulosic cell wall has been removed, but the plasma membrane is intact. One of the main features of plant cells is their strong plasticity, and their propensity to regenerate an organism from a single cell. Methods and differentiation protocols used in plant physiology and biology usually involve macroscopic vessels and containers that make difficult, for example, to follow the fate of the same protoplast all along its full development cycle, but also to perform continuous studies of the influence of various gradients in this context. These limits have hampered the precise study of regeneration processes. RESULTS: Herein, we present the design of a comprehensive, physiologically relevant, easy-to-use and low-cost microfluidic and microscopic setup for the monitoring of Physcomitrella patens (P. patens) growth and development on a long-term basis. The experimental solution we developed is made of two parts (i) a microfluidic chip composed of a single layer of about a hundred flow-through microfluidic traps for the immobilization of protoplasts, and (ii) a low-cost, light-controlled, custom-made microscope allowing the continuous recording of the moss development in physiological conditions. We validated the experimental setup with three proofs of concepts: (i) the kinetic monitoring of first division steps and cell wall regeneration, (ii) the influence of the photoperiod on growth of the protonemata, and (iii) finally the induction of leafy buds using a phytohormone, cytokinin. CONCLUSIONS: We developed the design of a comprehensive, physiologically relevant, easy-to-use and low-cost experimental setup for the study of P. patens development in a microfluidic environment. This setup allows imaging of P. patens development at high resolution and over long time periods.
RESUMO
Alcanivorax borkumensis is a ubiquitous marine bacterium that utilizes alkanes as a sole carbon source. We observed two phenotypes in the A. borkumensis SK2 type strain: rough (R) and smooth (S) types. The S type exhibited lower motility and higher polysaccharide production than the R type. Full genome sequencing revealed a mutation in the S type involved in cyclic-di-GMP production. The present results suggest that higher c-di-GMP levels in the S type control the biofilm forming behavior of this bacterium in a manner commensurate with other Gram-negative bacteria.
Assuntos
Alcanivoraceae/fisiologia , Proteínas de Bactérias/genética , Biofilmes/crescimento & desenvolvimento , GMP Cíclico/análogos & derivados , Alcanivoraceae/genética , Alcanivoraceae/metabolismo , Alcanos/metabolismo , Proteínas de Bactérias/metabolismo , GMP Cíclico/metabolismo , Regulação Bacteriana da Expressão Gênica , Genoma Bacteriano/genética , Fenótipo , Mutação Puntual , Polissacarídeos Bacterianos/biossínteseRESUMO
BACKGROUND: Genome-wide characterization of tissue- or cell-specific gene expression is a recurrent bottleneck in biology. We have developed a sensitive approach based on ultra-low RNA sequencing coupled to laser assisted microdissection for analyzing different tissues of the small Arabidopsis embryo. METHODS AND RESULTS: We first characterized the number of genes detected according to the quantity of tissue yield and total RNA extracted. Our results revealed that as low as 0.02 mm2 of tissue and 50 pg of total RNA can be used without compromising the number of genes detected. The optimised protocol was used to compare the epidermal versus mesophyll cell transcriptomes of cotyledons at the torpedo-shaped stage of embryo development. The approach was validated by the recovery of well-known epidermal genes such AtML1 or AtPDF2 and genes involved in flavonoid and cuticular waxes pathways. Moreover, the interest and sensitivity of this approach were highlighted by the characterization of several transcription factors preferentially expressed in epidermal cells. CONCLUSION: This technical advance unlocks some current limitations of transcriptomic analyses and allows to investigate further and efficiently new biological questions for which only a very small amounts of cells need to be isolated. For instance, it paves the way to increasing the spatial accuracy of regulatory networks in developing small embryo of Arabidopsis or other plant tissues.
RESUMO
In the plant cell wall, boron links two pectic domain rhamnogalacturonan II (RG-II) chains together to form a dimer and thus contributes to the reinforcement of cell adhesion. We studied the mur1-1 mutant of Arabidopsis thaliana which has lost the ability to form GDP-fucose in the shoots and show that the extent of RG-II cross-linking is reduced in the lignified stem of this mutant. Surprisingly, MUR1 mutation induced an enrichment of resistant interunit bonds in lignin and triggered the overexpression of many genes involved in lignified tissue formation and in jasmonic acid signaling. The defect in GDP-fucose synthesis induced a loss of cell adhesion at the interface between stele and cortex, as well as between interfascicular fibers. This led to the formation of regenerative xylem, where tissue detachment occurred, and underlined a loss of resistance to mechanical forces. Similar observations were also made on bor1-3 mutant stems which are altered in boron xylem loading, leading us to suggest that diminished RG-II dimerization is responsible for regenerative xylem formation.
Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/metabolismo , Guanosina Difosfato Fucose/metabolismo , Lignina/metabolismo , Mutação , Pectinas/metabolismo , Arabidopsis/genética , Pectinas/químicaRESUMO
In the normal cerebellum, Purkinje cells (PCs) are generated in a zone along the ventricular surface, migrate radially, and align to form a single-cell layer. However, in mice lacking the secreted protein Reelin or its downstream adaptor protein Dab1, the majority of PCs are located ectopically in the deep cerebellar mass. Nonetheless, how Reelin regulates migration and alignment of PCs remains incompletely understood. Reelin has a highly-conserved C-terminal region (CTR), which is required for its full activity. Here, we report an abnormality of the cerebellum in Reelin CTR-lacking knock-in (ΔC-KI) mice. In the ΔC-KI mice, cerebellar formation was largely normal, but some PCs in selected regions were found to be located ectopically and to frequently form clusters. Ectopic PCs contained a higher amount of Dab1 protein and functional Reelin receptors, including mainly very low-density lipoprotein receptor than correctly-aligned PCs. Decreasing Dab1 gene dosage exacerbated mislocalization of PCs and the cerebellar structure in Reelin ΔC-KI mice. These results indicate that ectopic PCs in ΔC-KI mice failed to receive sufficient Reelin signaling en route to their final destinations. Further, we also found that Reelin protein with intact CTR binds preferentially to PCs. Thus, it was suggested that the extent or quality of Reelin/Dab1 signaling that PCs require for correct positioning vary and that Reelin with intact CTR is required for that of a certain subset of PCs.
Assuntos
Moléculas de Adesão Celular Neuronais/metabolismo , Cerebelo/metabolismo , Proteínas da Matriz Extracelular/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Células de Purkinje/citologia , Receptores de Superfície Celular/metabolismo , Serina Endopeptidases/metabolismo , Animais , Cerebelo/crescimento & desenvolvimento , Camundongos Transgênicos , Fosforilação , Receptores de LDL/metabolismo , Proteína ReelinaRESUMO
The secreted glycoprotein Reelin is believed to play critical roles in the pathogenesis of several neuropsychiatric disorders. The highly basic C-terminal region (CTR) of Reelin is necessary for efficient activation of its downstream signaling, and the brain structure of knock-in mice that lack the CTR (ΔC-KI mice) is impaired. Here, we performed a comprehensive behavioral test battery on ΔC-KI mice, in order to evaluate the effects of partial loss-of-function of Reelin on brain functions. The ΔC-KI mice were hyperactive and exhibited reduced anxiety-like and social behaviors. The working memory in ΔC-KI mice was impaired in a T-maze test. There was little difference in spatial reference memory, depression-like behavior, prepulse inhibition, or fear memory between ΔC-KI and wild-type mice. These results suggest that CTR-dependent Reelin functions are required for some specific normal brain functions and that ΔC-KI mice recapitulate some aspects of neuropsychiatric disorders, such as schizophrenia, bipolar disorder, and autism spectrum disorder.
Assuntos
Comportamento Animal , Encéfalo , Moléculas de Adesão Celular Neuronais , Proteínas da Matriz Extracelular , Transtornos Mentais , Proteínas do Tecido Nervoso , Serina Endopeptidases , Comportamento Social , Animais , Encéfalo/metabolismo , Encéfalo/patologia , Encéfalo/fisiopatologia , Moléculas de Adesão Celular Neuronais/genética , Moléculas de Adesão Celular Neuronais/metabolismo , Proteínas da Matriz Extracelular/genética , Proteínas da Matriz Extracelular/metabolismo , Transtornos Mentais/genética , Transtornos Mentais/metabolismo , Transtornos Mentais/fisiopatologia , Camundongos , Camundongos Mutantes , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismo , Domínios Proteicos , Proteína Reelina , Serina Endopeptidases/genética , Serina Endopeptidases/metabolismoRESUMO
The interphase cell nucleus is extraordinarily complex, ordered, and dynamic. In the last decade, remarkable progress has been made in deciphering the functional organisation of the cell nucleus, and intricate relationships between genome functions (transcription, DNA repair, or replication) and various nuclear compartments have been revealed. In this review, we describe the architecture of the Arabidopsis thaliana interphase cell nucleus and discuss the dynamic nature of its organisation. We underline the need for further developments in quantitative and modelling approaches to nuclear organization.
Assuntos
Arabidopsis/genética , Núcleo Celular/genética , Cromatina/genética , Cromossomos de Plantas/genética , Interfase/genética , Animais , HumanosAssuntos
Sistema Enzimático do Citocromo P-450/metabolismo , Queratinas/metabolismo , Pele/metabolismo , Cálcio/metabolismo , Células Cultivadas , Sistema Enzimático do Citocromo P-450/genética , Regulação da Expressão Gênica no Desenvolvimento , Idade Gestacional , Humanos , Lipoxigenase/metabolismo , RNA Mensageiro/metabolismo , Receptores de Superfície Celular/metabolismo , Pele/embriologiaAssuntos
Transportadores de Cassetes de Ligação de ATP/genética , Apoptose/fisiologia , Ictiose Lamelar , Queratinócitos/fisiologia , Proteínas Proto-Oncogênicas c-akt/fisiologia , Animais , Células Cultivadas , Humanos , Ictiose Lamelar/genética , Ictiose Lamelar/patologia , Ictiose Lamelar/fisiopatologia , Queratinócitos/patologia , Camundongos , Camundongos MutantesAssuntos
Hiperceratose Epidermolítica/genética , Ceratodermia Palmar e Plantar/genética , Motivos de Aminoácidos/genética , Contratura/genética , Humanos , Hiperceratose Epidermolítica/complicações , Queratina-1/genética , Ceratodermia Palmar e Plantar/complicações , Masculino , Pessoa de Meia-Idade , Mutação de Sentido IncorretoRESUMO
Sjögren-Larsson syndrome is an autosomal-recessive hereditary disorder characterized by congenital ichthyosis, mental retardation and spastic diplegia or tetraplegia. It is known that mutations in the fatty aldehyde dehydrogenase (FALDH) gene (ALDH3A2) underlie SLS. We report two Indian sisters showing typical clinical features of SLS. Direct sequencing of the entire coding region of ALDH3A2 revealed a novel homozygous mutation, c.142G>T (p.Asp48Tyr) in exon 1, in both patients. Their parents harbored the mutation heterozygously. Mutant-allele-specific amplification analysis using PCR products as a template verified the mutation in the patients. The aspartic acid residue at the mutation site is located in the C-terminal portion of the second a-helix strand, a2, of N-terminal four helices of FALDH and the FALDH amino-acid sequence alignment shows that this aspartic acid residue is conserved among several diverse species. Until now, a number of mutations in ALDH3A2 have been shown to be responsible for SLS in Europe, the Middle East, Africa, and North and South America. However, in Asian populations, ALDH3A2 mutations have been identified only in Japanese SLS patients. Here we report an ALDH3A2 mutation for the first time in SLS patients in the Asian country other than Japan. The present results suggest that ALDH3A2 is a gene responsible for SLS in Asian populations. We hope ALDH3A2 mutation search will be globally available including many Asian countries in the future.
Assuntos
Aldeído Oxirredutases/genética , Mutação de Sentido Incorreto , Síndrome de Sjogren-Larsson/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Bovinos , Pré-Escolar , Éxons , Feminino , Humanos , Lactente , Camundongos , Dados de Sequência Molecular , Ratos , Alinhamento de Sequência , Síndrome de Sjogren-Larsson/diagnósticoRESUMO
Harlequin ichthyosis (HI) is caused by loss-of-function mutations in the keratinocyte lipid transporter ABCA12. The patients often die in the first 1 or 2 weeks of life, although HI survivors' phenotypes improve within several weeks after birth. In order to clarify the mechanisms of phenotypic recovery, we studied grafted skin and keratinocytes from Abca12-disrupted (Abca12(-/-)) mice showing abnormal lipid transport. Abca12(-/-) neonatal epidermis showed significantly reduced total ceramide amounts and aberrant ceramide composition. Immunofluorescence and immunoblotting of Abca12(-/-) neonatal epidermis revealed defective profilaggrin/filaggrin conversion and reduced protein expression of the differentiation-specific molecules, loricrin, kallikrein 5, and transglutaminase 1, although their mRNA expression was up-regulated. In contrast, Abca12(-/-) skin grafts kept in a dry environment exhibited dramatic improvements in all these abnormalities. Increased transepidermal water loss, a parameter representing barrier defect, was remarkably decreased in grafted Abca12(-/-) skin. Ten-passage sub-cultured Abca12(-/-) keratinocytes showed restoration of intact ceramide distribution, differentiation-specific protein expression and profilaggrin/filaggrin conversion, which were defective in primary-cultures. Using cDNA microarray analysis, lipid transporters including four ATP-binding cassette transporters were up-regulated after sub-culture of Abca12(-/-) keratinocytes compared with primary-culture. These results indicate that disrupted keratinocyte differentiation during the fetal development is involved in the pathomechanism of HI and, during maturation, Abca12(-/-) epidermal keratinocytes regain normal differentiation processes. This restoration may account for the skin phenotype improvement observed in HI survivors.