Cells constantly adapt to changes in their environment. In the majority of cases, the environment shifts between conditions that were previously encountered during the course of evolution, thus enabling evolutionary-programmed responses. In rare cases, however, cells may encounter a new environment to which a novel response is required. To characterize the first steps in adaptation to a novel condition, we studied budding yeast growth on xylulose, a sugar that is very rarely found in the wild. We previously reported that growth on xylulose induces the expression of amino-acid biosynthesis genes, in multiple natural yeast isolates. This induction occurs despite the presence of amino acids in the growth medium and is a unique response to xylulose, not triggered by any of the naturally available carbon sources tested. Propagating these strains for ~300 generations on xylulose significantly improved their growth rate. Notably, the most significant change in gene expression was the loss of amino acid biosynthesis gene induction. Furthermore, the reduction in amino-acid biosynthesis gene expression on xylulose was strongly correlated with the improvement in growth rate, suggesting that internal depletion of amino-acids presented the major bottleneck limiting growth in xylulose. We discuss the possible implications of our results for explaining how cells maintain the balance between supply and demand of amino acids during growth in evolutionary 'familiar' vs. 'novel' conditions. Overall design: mRNA profiles of 12 wt S. cerevisiae strains grown on either YPD or YP-xylulose, before and after 300 generations evolution on YP-xylulose
Rapid evolutionary adaptation to growth on an 'unfamiliar' carbon source.
Cell line, Subject
View SamplesFor each strain two time courses for mRNA abundance: Oxidative and MMS and two time courses for decay: reference decay and following oxidative stress
Transcriptome kinetics is governed by a genome-wide coupling of mRNA production and degradation: a role for RNA Pol II.
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View SamplesWe created a comprehensive tRNA deletion library in yeast and characterized the phenotypic and further characterized the molecular changes in a subset of deletion strains
A comprehensive tRNA deletion library unravels the genetic architecture of the tRNA pool.
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View SamplesRNA localization is a regulatory mechanism that is conserved from bacteria to mammals. Yet, little is known about the mechanism and the logic that govern the distribution of RNA transcripts within the cell. Here we present a novel organ culture system, which enables the isolation of RNA specifically from NGF dependent re-growing peripheral axons of mouse embryo sensory neurons. In combination with massive parallel sequencing technology, we determine the sub-cellular localization of most transcripts in the transcriptome. We found that the axon is enriched in mRNAs that encode secreted proteins, transcription factors and the translation machinery. In contrast, the axon was largely depleted from mRNAs encoding transmembrane proteins, a particularly interesting finding, since many of these gene products are specifically expressed in the tip of the axon at the protein level. Comparison of the mitochondrial mRNAs encoded in the nucleus with those encoded in the mitochondria, uncovered completely different localization pattern, with the latter much enriched in the axon fraction. This discovery is intriguing since the protein products encoded by the nuclear and mitochondrial genome form large co-complexes. Finally, focusing on alternative splice variants that are specific to axonal fractions, we find short sequence motifs that are enriched in the axonal transcriptome. Together our findings shed light on the extensive role of RNA localization and its characteristics. Overall design: For each RNA sample, Spinal Cords\ DRGs were dissected from 40 E13.5 embryos and cultured for 48H. Total RNA was extracted from whole DRG and Peripheral axons. Poly-A enriched. In duplicates, using GAIIx. Read length - 80nt.
Subcellular transcriptomics-dissection of the mRNA composition in the axonal compartment of sensory neurons.
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View SamplesWe subjected yeast to two stresses, oxidative stress, which under current settings induces a fast and transient response in mRNA abundance, and DNA damage, which triggers a slow enduring response. Using microarrays, we performed a transcriptional arrest experiment to measure genome-wide mRNA decay profiles under each condition. Genome-wide decay kinetics in each condition were compared to decay experiments that were performed in a reference condition (only transcription inhibition without an additional stress) to quantify changes in mRNA stability in each condition. We found condition-specific changes in mRNA decay rates and coordination between mRNA production and degradation. In the transient response, most induced genes were surprisingly destabilized, while repressed genes were somewhat stabilized, exhibiting counteraction between production and degradation. This strategy can reconcile high steady-state level with short response time among induced genes. In contrast, the stress that induces the slow response displays the more expected behavior, whereby most induced genes are stabilized, and repressed genes destabilized. Our results show genome-wide interplay between mRNA production and degradation, and that alternative modes of such interplay determine the kinetics of the transcriptome in response to stress.
Transient transcriptional responses to stress are generated by opposing effects of mRNA production and degradation.
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View SamplesWe conducted a set of lab-evolution experiments in yeast and followed the long-term dynamics of aneuploidy under diverse conditions including heat shock and high PH.
Chromosomal duplication is a transient evolutionary solution to stress.
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View SamplesRetrograde signaling from axon to soma activates intrinsic regeneration mechanisms in lesioned peripheral sensory neurons; however, the links between axonal injury signaling and the cell body response are not well understood. Here, we used phosphoproteomics and microarrays to implicate ~900 phosphoproteins in retrograde injury signaling in rat sciatic nerve axons in vivo and ~4500 transcripts in the in vivo response to injury in the dorsal root ganglia. Computational analyses of these data sets identified ~400 redundant axonal signaling networks connected to 39 transcription factors implicated in the sensory neuron response to axonal injury. Experimental perturbation of individual overrepresented signaling hub proteins, including Abl, AKT, p38, and protein kinase C, affected neurite outgrowth in sensory neurons. Paradoxically, however, combined perturbation of Abl together with other hub proteins had a reduced effect relative to perturbation of individual proteins. Our data indicate that nerve injury responses are controlled by multiple regulatory components, and suggest that network redundancies provide robustness to the injury response
Signaling to transcription networks in the neuronal retrograde injury response.
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View SamplesA fundamental issue in cell biology is how migratory cell behaviors are controlled by dynamically regulated cell adhesion.
Ovo1 links Wnt signaling with N-cadherin localization during neural crest migration.
Age, Specimen part
View SamplesWe initiated a study to investigate the transcriptional profiles associated with cell states of the stomatal lineage. A stem-cell like precursor of stomata, a meristemoid. reiterates asymmetric divisions and renews itself before differentiating into guard cells. The transient and asynchronous nature of the meristemoid has made it difficult to study its molecular characteristics. Through combinatorial use of genetic resources that either arrest or constitutively drive stomatal cell-state progressions due to loss- or gain-of-function mutations in the key transcription factor genes, SPEECHLESS, MUTE, and SCRM, we obtained seedlings highly enriched in pavement cells, meristemoids, or stomata. Here we present transcriptome and genome-wide trends in gene regulation associated with each cell state and identify molecular signatures associated with meristemoids.
Molecular profiling of stomatal meristemoids reveals new component of asymmetric cell division and commonalities among stem cell populations in Arabidopsis.
Age, Specimen part
View SamplesSIN3 is a master transcriptional scaffold protein. SIN3 interacts with RPD3 and other accessory proteins to form a histone modifying complex. A single Sin3A gene encodes multiple isoforms of SIN3, of which SIN3 187 and SIN3 220 are the predominant isoforms. Previous studies demonstrated that SIN3 isoforms play non-redundant roles during fly development. In the current study, we sought to investigate the genes regulated by SIN3 187. Overall design: S2 cells and cells carrying a stable transgene of SIN3 187HA (SIN3 187HA cells) were treated with 0.07 µM CuSO4. CuSO4 treatment led to ectopic expression of SIN3 187HA. S2 cells were used as a control. Following induction, total mRNA was extracted. mRNA profiling of these samples were performed by deep sequencing using Illumina Hiseq2500. Three biological replicates were performed.
Genome-wide studies reveal novel and distinct biological pathways regulated by SIN3 isoforms.
Cell line, Subject
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