Genetic Analysis of opaque 2 Modifier Loci in Quality Protein Maize
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ABSTRACT:
ORGANISM(S): Zea mays
PROVIDER: GSE10449 | GEO | 2008/02/08
SECONDARY ACCESSION(S): PRJNA108001
REPOSITORIES: GEO
Similar Datasets
Project description:Quality Protein Maize (QPM) was created by selecting for genetic modifiers that convert the starchy endosperm of an opaque2 (o2) mutant to a hard, vitreous phenotype. Genetic analysis has shown there are multiple, unlinked o2 modifiers (Opm), but their identity and mode of action are unknown. A microarray hybridization performed with RNA obtained from true breeding o2 progeny with vitreous and opaque kernel phenotypes identified a small group of differentially expressed genes, some of which map at or near the Opm QTLs. Compared 18 days after pollination endosperm transcript profiles in true breeding modified (vitreous; V) and non-modified (opaque; O) opaque 2 kernels. Used four vitreous biological reps (V1-V4) and four opaque biological reps (O1-O4). Each biological rep is a pool of 25 kernels representing 5 kernels form each of 5 uniform phenotype ears (vitreous or opaque). Four arrays used: Array 1= V1 vs O1, Array 2 = V2 vs O2, Array 3 = V3 vs O3, Array 4 = V4 vs O4
2010-05-26 | E-GEOD-10449 | biostudies-arrayexpress
Project description:Reduced prolamin (zein) accumulation and defective ER-body formation occurs in maize opaque endosperm mutants opaque2 (o2), floury2 (fl2), defective endosperm*B30 (DeB30), and mucronate (Mc) whereas other opaque mutants such as opaque1 (o1) and floury1 (fl1) are normal in these regards. This suggests that other factors contribute to kernel texture. We used a LC-MS/MS proteomics approach to compare non-zein proteins of nearly isogenic opaque mutants. In total, 2762 proteins were identified that were enriched for biological processes such as protein transport and folding, amino acid biosynthesis, and proteolysis. Amino acid analysis of top proteins revealed qualitative changes in lysine abundance contributing to the overall lysine increase. Principal component analysis and pathway enrichment suggested that the mutants partition into three groups: Mc, DeB30, fl2 and o2; o1; and fl1. Indicator species analysis revealed mutant-specific proteins, and highlighted ER secretory pathway components that are enriched in selected groups of mutants, albeit with no common proteins across all mutants. Most significantly changed proteins were related to stress or defense and zein partitioning into the soluble fraction for Mc, DeB30, o1 and fl1 specifically. We suggest that ER stress is a universal trigger of opacity regardless of qualitative or quantitative changes in zein accumulation.
2016-01-05 | PXD002379 | Pride
Project description:Development of the cereal endosperm involves cell differentiation processes that enable nutrient uptake from the maternal plant, accumulation of storage products and their utilization during germination. However, little is known about the regulatory mechanisms that link cell differentiation processes with those controlling storage product synthesis and deposition, including the activation of zein genes by the maize (Zea mays) bZIP transcription factor Opaque-2 (O2). In this study, we mapped in vivo binding sites of O2 in B73 endosperm, and compared the results with genes differentially expressed in B73 and B73o2. We identified 186 putative direct O2 targets and 1,677 indirect targets, encoding a broad set of gene functionalities. Examination of the temporal expression patterns of O2 targets using real-time RT-PCR experiments revealed at least two distinct modes of O2-mediated gene activation. We also showed that two O2-activated genes, bZIP17 and NAKED ENDOSPERM2 (NKD2) encoded transcription factors, which can in turn co-activate other O2-network genes with O2. NKD2 (with its paralog NKD1) was previously shown to be involved in regulation of aleurone development. Collectively, our results provide novel insights into the complexity of the O2-regulated network and its role in regulation of endosperm cell differentiation and function.
2018-09-14 | GSE114343 | GEO
Project description:The human pathogen Candida albicans can assume either of two distinct cell types, designated ‘‘white’’ and ‘‘opaque.’’ Each cell type is maintained for many generations; switching between them is rare and stochastic, and occurs without any known changes in the nucleotide sequence of the genome. The two cell types differ dramatically in cell shape, colony appearance, mating competence, and virulence properties. In this work, we investigate the transcriptional circuitry that specifies the two cell types and controls the switching between them. First, we identify two new transcriptional regulators of white-opaque switching, Czf1 and white-opaque regulator 2 (Wor2). Analysis of a large set of double mutants and ectopic expression strains revealed genetic relationships between CZF1, WOR2, and two previously identified regulators of white-opaque switching, WOR1 and EFG1. Using chromatin immunoprecipitation, we show that Wor1 binds the intergenic regions upstream of the genes encoding three additional transcriptional regulators of white-opaque switching (CZF1, EFG1, and WOR2), and also occupies the promoters of numerous white- and opaque-enriched genes. Based on these interactions, we have placed these four genes in a circuit controlling white-opaque switching whose topology is a network of positive feedback loops, with the master regulator gene WOR1 occupying a central position. Our observations indicate that a key role of the interlocking feedback loop network is to stably maintain each epigenetic state through many cell divisions. Keywords: ChIP-chip
2007-10-01 | GSE8709 | GEO
Project description:Transcriptional profiling of C. tropicalis a cells (CAY1503) in opaque state and overexpressing Wor1 in biofilms hybridized against a universal mixed reference sample of a cells in white and opaque states grown in Spider liquid.
2013-05-01 | GSE43267 | GEO
Project description:In Candida albicans, the a1-alpha2 complex represses white-opaque switching as well as mating. A ChIP-chip strategy was, therefore, used to screen for genes with a1-alpha2 binding sites and expression patterns consistent with a master switch gene (MSG). Of 51 genes identified with an a1-alpha2 binding site, one gene, TOS9, also referred to as EAP2, exhibited an expression pattern consistent with a MSG. TOS9 is expressed in opaque, not white a/a and alpha/alpha cells and Tos9p localizes to the opaque cell nucleus. Deletion of TOS9 blocks cells in the white phase, and misexpression in the white phase of the parent tos9+/tos9+ strain results in mass conversion to opaque. Expression of TOS9 under control of a MET promoter rescues the TOS9 null mutant tos9-/tos9- phenotype. Temperature-induced mass conversion of opaque to white in the parent strain results in the immediate cessation of TOS9 transcription, and loss of Tos9p prior to the point of commitment to white (the switch event), which occurs at the time of the second cell doubling. Misexpression of TOS9, as well as inhibition of the second round of DNA replication inhibits the temperature-induced switch from opaque to white. Based on these observations, a model is developed for the regulation and role of TOS9 in switching. Keywords: ChIP chip
2006-09-19 | GSE5493 | GEO
Project description:The human fungal pathogen Candida albicans can switch between two cell types, “white” and “opaque,” each of which is heritable through many cell divisions. Switching between these two cell types is regulated by six transcriptional regulators which form a highly interconnected circuit with multiple feedback loops. Here, we identify a seventh regulator of white-opaque switching, which we have named Wor4. We show that ectopic expression of Wor4 is sufficient to drive switching from the white to the opaque cell type and that deletion of Wor4 blocks switching from the white to the opaque cell type. A combination of ectopic expression and deletion experiments indicates that Wor4 is positioned upstream of Wor1 and that it is formally an activator of the opaque cell type. The combination of ectopic expression and deletion phenotypes for Wor4 is unique; none of the other six white-opaque regulators show this pattern. We determined the pattern of Wor4 binding across the genome by ChIP-seq and found it is highly correlated with that of Wor1 and Wor2, indicating that Wor4 is tightly integrated into the existing white-opaque regulatory circuit. We previously proposed that white-to-opaque switching relies on the activation of a complex circuit of feedback loops that remains excited through many cell divisions. The identification of a new, central regulator of white-opaque switching supports this idea by indicating that the white-opaque switching mechanism is considerably more complex than those controlling conventional, non-heritable patterns of gene expression.
2016-01-11 | GSE75124 | GEO
Project description:Transcriptional profiling of C. tropicalis a cells (CAY1503) in opaque state and overexpressing Wor1 in biofilms hybridized against a universal mixed reference sample of a cells in white and opaque states grown in Spider liquid. 2 condition experiment: opaque, tdh3-wor1; 2 biological replicates of each
2013-05-01 | E-GEOD-43267 | biostudies-arrayexpress
Project description:As a successful commensal and pathogen of humans, Candida albicans encounters a wide range of environmental changes. Among them, ambient pH is an important factor, which changes frequently and affects many biological processes in this species. The ability to adapt to pH changes is tightly linked with pathogenesis and morphogenesis. In this study, we report that pH has a profound effect on white-opaque switching and sexual mating in C. albicans. Acidic pHs promote white-to-opaque switching but repress sexual mating of opaque cells. The cAMP signaling and Rim101-mediated pH sensing pathways are involved in the regulation of pH-regulated white-opaque switching. Interestingly, white and opaque cells of the cyr1/cyr1 mutant, which is defective in producing cAMP, show distinct growth defects under acidic and alkaline conditions. Phr2 could play a major role in acidic pHs-induced opaque cell formation. We further discover that acidic pH conditions repress sexual mating due to the failure of activation of the Ste2-mediated a-pheromone response pathway. The effects of pH changes on phenotypic switching and sexual mating could be a balance behavior between host adaptation and sexual reproduction.
2015-12-30 | GSE67101 | GEO
Project description:Modes of sexual reproduction in eukaryotic organisms are highly diversified. The human fungal pathogen Candida albicans undergoes a phenotypic switch from the white to the opaque phase in order to become mating-competent. In this study, we report that functionally and morphologically differentiated white and opaque cells show a coordinating behavior in the process of mating. Although white cells are mating-incompetent, they are induced to produce sexual pheromones when treated with opposite pheromones or interacted with opaque cells of an opposite mating type. In a co-culture system, pheromones released by white cells induce opaque cells to form mating projections and thus facilitate both opposite- and same-sex mating of opaque cells. Deletion of genes encoding the pheromone precursor proteins and inactivation of the pheromone response signaling pathway (Ste2-MAPK-Cph1) impair the promoting role of white cells (MTLa) in sexual mating of opaque cells. White and opaque cells communicate via a paracrine pheromone signaling and thus create an environment conducive to sexual mating. This coordination behavior of the two different cell types may be a trade-off strategy between sexual and asexual lifestyles in C. albicans.
2014-10-23 | GSE56039 | GEO