- Plant dual-specificity tyrosine phosphorylation-regulated kinase optimizes light-regulated growth and development in Arabidopsis. [Journal Article]
- PCPlant Cell Environ 2017 Apr 24
- Light controls vegetative and reproductive development of plants. For a plant, sensing the light input properly ensures coordination with the ever-changing environment. Previously, we found that LIGH...
Light controls vegetative and reproductive development of plants. For a plant, sensing the light input properly ensures coordination with the ever-changing environment. Previously, we found that LIGHT-REGULATED WD1 (LWD1) and LWD2 regulate the circadian clock and photoperiodic flowering. Here we identified Arabidopsis YET ANOTHER KINASE1 (AtYAK1), an evolutionarily conserved protein and a member of dual-specificity tyrosine phosphorylation-regulated kinases (DYRKs), as an interacting protein of LWDs. Our study revealed that AtYAK1 is an important regulator for various light responses, including the circadian clock, photomorphogenesis and reproductive development. AtYAK1 could antagonize the function of LWDs in regulating the circadian clock and photoperiodic flowering. By examining phenotypes of atyak1, we found that AtYAK1 regulated light-induced period-length shortening and photomorphogenic development. Moreover, AtYAK1 mediated plant fertility especially under inferior light conditions including low light and short-day length. This study discloses a new regulator connecting environmental light to plant growth.
- Ex vivo cultures combined with vivo-morpholino induced gene knockdown provide a system to assess the role of WT1 and GATA4 during gonad differentiation. [Journal Article]
- PlosPLoS One 2017; 12(4):e0176296
- Gonad morphogenesis relies on the correct spatiotemporal expression of a number of genes that together fulfill the differentiation of the bipotential gonad into testes or ovaries. As such, the transc...
Gonad morphogenesis relies on the correct spatiotemporal expression of a number of genes that together fulfill the differentiation of the bipotential gonad into testes or ovaries. As such, the transcription factors WT1 and GATA4 are pivotal for proper gonadal development. Here we address the contributions of GATA4 and WT1 to the sex differentiation phase in testes and ovaries. We applied an ex vivo technique for cultivating gonads in hanging droplets of media that were supplemented with vivo-morpholinos to knockdown WT1 and GATA4 either alone or in combination at the same developmental stage. We show that WT1 is equally important for both, the initial establishment and the maintenance of the sex-specific gene expression signature in testes and ovaries. We further identified Foxl2 as a novel putative downstream target gene of WT1. Moreover, knockdown of WT1 reduced mRNA levels of several molecular components of the hedgehog signaling pathway in XY gonads, whereas Gata4 vivo-morpholino treatment increased transcripts of Dhh and Ptch1 in embryonic testes. The data suggest that for its proper function, WT1 relies on the correct expression of the GATA4 protein. Furthermore, GATA4 down-regulates several ovarian promoting genes in testes, such as Ctnnb1, Fst, and Bmp2, suggesting that this repression is required for maintaining the male phenotype. In conclusion, this study provides novel insights into the role of WT1 and GATA4 during the sex differentiation phase and represents an approach that can be applied to assess other proteins with as yet unknown functions during gonadal development.
- A multiplex culture system for the long-term growth of fission yeast cells. [Journal Article]
- YYeast 2017 Apr 20
- Maintenance of long-term cultures of yeast cells is central to a broad range of investigations, from metabolic studies to laboratory evolution assays. However, repeated dilutions of batch cultures le...
Maintenance of long-term cultures of yeast cells is central to a broad range of investigations, from metabolic studies to laboratory evolution assays. However, repeated dilutions of batch cultures lead to variations in medium composition, with implications for cell physiology. In S. cerevisiae, powerful miniaturized chemostat setups, or ministat arrays, have been shown to allow for constant dilution of multiple independent cultures. Here we set out to adapt these arrays for continuous culture of a morphologically and physiologically distinct yeast, the fission yeast Schizosaccharomyces pombe, with the goal of maintaining constant population density over time. First, we demonstrated that the original ministats are incompatible with growing fission yeast for more than a few generations, prompting us to modify different aspects of the system design. Next, we identified critical parameters for sustaining unbiased vegetative growth in these conditions. This requires deletion of the gsf2 flocculin-encoding gene, along with addition of galactose to the medium and lowering of the culture temperature. Importantly, we improved the flexibility of the ministats by developing a piezo-pump module for the independent regulation of the dilution rate of each culture. This made it possible to easily grow strains that have different generation times in the same assay. Our system therefore allows for maintaining multiple fission yeast cultures in exponential growth, adapting the dilution of each culture over time to keep constant population density for hundreds of generations. These multiplex culture systems open the door to a new range of long-term experiments using this model organism.
- Photosynthetic responses to temperature across leaf-canopy-ecosystem scales: a 15-year study in a Californian oak-grass savanna. [Journal Article]
- PRPhotosynth Res 2017 Apr 19
- Ecosystem CO2 fluxes measured with eddy-covariance techniques provide a new opportunity to retest functional responses of photosynthesis to abiotic factors at the ecosystem level, but examining the e...
Ecosystem CO2 fluxes measured with eddy-covariance techniques provide a new opportunity to retest functional responses of photosynthesis to abiotic factors at the ecosystem level, but examining the effects of one factor (e.g., temperature) on photosynthesis remains a challenge as other factors may confound under circumstances of natural experiments. In this study, we developed a data mining framework to analyze a set of ecosystem CO2 fluxes measured from three eddy-covariance towers, plus a suite of abiotic variables (e.g., temperature, solar radiation, air, and soil moisture) measured simultaneously, in a Californian oak-grass savanna from 2000 to 2015. Natural covariations of temperature and other factors caused remarkable confounding effects in two particular conditions: lower light intensity at lower temperatures and drier air and soil at higher temperatures. But such confounding effects may cancel out. At the ecosystem level, photosynthetic responses to temperature did follow a quadratic function on average. The optimum value of photosynthesis occurred within a narrow temperature range (i.e., optimum temperature, T opt): 20.6 ± 0.6, 18.5 ± 0.7, 19.2 ± 0.5, and 19.0 ± 0.6 °C for the oak canopy, understory grassland, entire savanna, and open grassland, respectively. This paradigm confirms that photosynthesis response to ambient temperature changes is a functional relationship consistent across leaf-canopy-ecosystem scales. Nevertheless, T opt can shift with variations in light intensity, air dryness, or soil moisture. These findings will pave the way to a direct determination of thermal optima and limits of ecosystem photosynthesis, which can in turn provide a rich resource for baseline thresholds and dynamic response functions required for predicting global carbon balance and geographic shifts of vegetative communities in response to climate change.
- Sporulation: how to survive on planet Earth (and beyond). [Review]
- CGCurr Genet 2017 Apr 18
- Sporulation is a strategy widely utilized by a wide variety of organisms to adapt to changes in their individual environmental niches and survive in time and/or space until they encounter conditions ...
Sporulation is a strategy widely utilized by a wide variety of organisms to adapt to changes in their individual environmental niches and survive in time and/or space until they encounter conditions acceptable for vegetative growth. The spores produced by bacteria have been the subjects of extensive studies, and several systems such as Bacillus subtilis have provided ample opportunities to understand the molecular basis of spore biogenesis and germination. In contrast, the spores of other microbes, such as fungi, are relatively poorly understood. Studies of sporulation in model systems such as Saccharomyces cerevisiae and Aspergillus nidulans have established a basis for investigating eukaryotic spores, but very little is known at the molecular level about how spores function. This is especially true among the spores of human fungal pathogens such as the most common cause of fatal fungal disease, Cryptococcus neoformans. Recent proteomic studies are helping to determine the molecular mechanisms by which pathogenic fungal spores are formed, persist and germinate into actively growing agents of human disease.
- Mitochondrial and peroxisomal Lon proteases play opposing roles in reproduction and growth but co-function in the normal development, stress resistance and longevity of Thermomyces lanuginosus. [Journal Article]
- FGFungal Genet Biol 2017 Apr 12
- The ATP-dependent Lon enzyme is a highly conserved protease with multiple roles in diverse species such as fungi; however, there are few reports on Lon enzymes in filamentous fungi. Thermomyces lanug...
The ATP-dependent Lon enzyme is a highly conserved protease with multiple roles in diverse species such as fungi; however, there are few reports on Lon enzymes in filamentous fungi. Thermomyces lanuginosus, a typical thermophilic fungus, has been widely studied in physiology and cell biology; thus, studies on Thermomyces Lons are important. Two Lons were bioinformatically deduced in T. lanuginosus. Subcellular localization analysis showed that one is present in mitochondria (MLon), while the other is found in peroxisomes (PLon). Although both Lon enzymes were activated by H2O2, they were not induced by heat shock; instead, they were induced by low temperatures. Two single-deletion Lon mutants (ΔMLon and ΔPLon) were generated. Biological analysis demonstrated that ΔMLon decreased the production of conidia but increased the growth of mycelia. By contrast, ΔPLon increased the production of conidia but decreased the growth of mycelia. The lifespan was measured in time and in length of continuous growth. The wild-type strain showed continuous linear growth for 60 days, whereas growth was impeded at 30 and 50 days for ΔPLon and ΔMLon mutants, respectively, suggesting that PLon is more important for longevity than MLon. Interestingly, ΔPLon, which accumulated larger amount of H2O2 was not only more sensitive to exogenous H2O2 but also much more sensitive to other selected stressors. Taken together, our data indicate that mitochondrial and peroxisomal Lons play opposite roles in controlling growth and development, but exhibit synergistic effects on the normal states of vegetative growth, asexual development, stress resistance and longevity in T. lanuginosus.
- 1-Aminocyclopropane-1-Carboxylate Oxidase Induction in Tomato Flower Pedicel Phloem and Abscission Related Processes Are Differentially Sensitive to Ethylene. [Journal Article]
- FPFront Plant Sci 2017; 8:464
- Ethylene has impact on several physiological plant processes, including abscission, during which plants shed both their vegetative and reproductive organs. Cell separation and programmed cell death a...
Ethylene has impact on several physiological plant processes, including abscission, during which plants shed both their vegetative and reproductive organs. Cell separation and programmed cell death are involved in abscission, and these have also been correlated with ethylene action. However, the detailed spatiotemporal pattern of the molecular events during abscission remains unknown. We examined the expression of two tomato ACO genes, LeACO1, and LeACO4 that encode the last enzyme in ethylene biosynthesis, 1-aminocyclopropane-1-carboxylate oxidase (ACO), together with the expression of other abscission-associated genes involved in cell separation and programmed cell death, during a period of 0-12 h after abscission induction in the tomato flower pedicel abscission zone and nearby tissues. In addition, we determined their localization in specific cell layers of the flower pedicel abscission zone and nearby tissues obtained by laser microdissection before and 8 h after abscission induction. The expression of both ACO genes was localized to the vascular tissues in the pedicel. While LeACO4 was more uniformly expressed in all examined cell layers, the main expression site of LeACO1 was in cell layers just outside the abscission zone in its proximal and distal part. We showed that after abscission induction, ACO1 protein was synthesized in phloem companion cells, in which it was localized mainly in the cytoplasm. Samples were additionally treated with 1-methylcyclopropene (1-MCP), a competitive inhibitor of ethylene actions, and analyzed 8 h after abscission induction. Cell-layer-specific changes in gene expression were observed together with the specific localization and ethylene sensitivity of the hallmarks of cell separation and programmed cell death. While treatment with 1-MCP prevented separation of cells through inhibition of the expression of polygalacturonases, which are the key enzymes involved in degradation of the middle lamella, this had less impact on the occurrence of different kinds of membrane vesicles and abscission-related programmed cell death. In the flower pedicel abscission zone, the physical progressions of cell separation and programmed cell death are perpendicular to each other and start in the vascular tissues.
- Research funding: Do you get what you pay for? [Editorial]
- APActa Physiol (Oxf) 2017 Apr 12
- Our society is based on transactions. As customers, we expect to be treated not only politely, but obligingly, by the providers of products or services we pay for. Return policies ensure that, more o...
Our society is based on transactions. As customers, we expect to be treated not only politely, but obligingly, by the providers of products or services we pay for. Return policies ensure that, more often than not, we actually get what we pay for. Significantly more often. And then, everything is different when research is funded commercially. If, however, customers get what they pay for, this is nice material for a little scandal (1). This intro is meant to be provocative, but it may be worth attempting a look behind a field that has much more than COI declarations. This article is protected by copyright. All rights reserved.
- JMJ24 antagonizes histone H3K9 demethylase IBM1/JMJ25 function and interacts with RNAi pathways for gene silencing. [Journal Article]
- GEGene Expr Patterns 2017 Apr 08; 25-26:1-7
- Dimethylation of histone H3 lysine 9 (H3K9me2) is a heterochromatic mark linked to DNA methylation and gene repression. Removal of H3K9me2 from gene bodies by the jmjC histone demethylase IBM1/JMJ25 ...
Dimethylation of histone H3 lysine 9 (H3K9me2) is a heterochromatic mark linked to DNA methylation and gene repression. Removal of H3K9me2 from gene bodies by the jmjC histone demethylase IBM1/JMJ25 inhibits DNA methylation and derepresses gene expression. In this work, we analyzed the function of a closely related homolog of IBM1/JMJ25, namely JMJ24. We show that jmj24 mutations produced a number of subtle developmental defects, while affecting only a relatively small number of genes at the vegetative stage. Interestingly, jmj24 mutation could complement plant growth defects and expression changes caused by the ibm1 mutation. In addition, we show that JMJ24 may synergistically interact with the RNAi pathways involving siRNAs. The present data suggest that JMJ24 may have a function to counteract IBM1/JMJ25 in gene expression and may cooperate with RNAi pathways for gene silencing.
New Search Next
- The pH-dependent assembly of Chaplin E from Streptomyces coelicolor. [Journal Article]
- JSJ Struct Biol 2017 Apr 08
- Chaplin E, is one of five self-assembling peptides secreted by Streptomyces coelicolor that assist aerial growth by lowering the surface tension of water. Although the surface activity of a mixture o...
Chaplin E, is one of five self-assembling peptides secreted by Streptomyces coelicolor that assist aerial growth by lowering the surface tension of water. Although the surface activity of a mixture of chaplin peptides has observed to depend on pH, it is unclear how the solvent environment (i.e. pH) influences the structure, assembly and subsequent functionality of these individual peptides. In this study, the conformation and fibril forming propensity of the Chaplin E peptide was assessed as a function of pH using a combination of experimental measurements and molecular dynamics simulations. At an acidic pH of 3.0, Chaplin E retained a random coil structure, whereas at the isoelectric point of 6.7 or a basic pH of 10.0, Chaplin E rapidly formed amyloid fibrils rich in β-sheet structure with high efficiency (>93%). Molecular dynamics simulations indicate the persistence of greater α-helical content at the N-terminus at high pH; this is likely partly due to the lack of electrostatic repulsion between residues His6 and Lys10. Since fibril formation was observed at high but not at low pH, we propose that the presence of an N-terminal α-helix in the monomeric form of Chaplin E is required for aggregation and conversion to β-amyloid fibrils. The pH sensitivity of Chaplin E peptide structure provides a route to control peptide assembly and may be important for the physiological function of this peptide, as a surface active agent in the transition from vegetative to aerial growth and could assist Streptomyces coelicolor in response to environmental fluctuations in pH.