| 1. |
- Concepcion Cruz-Santos, Maria, et al.
(author)
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The Role of microRNAs in Animal Cell Reprogramming
- 2016
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In: Stem Cells and Development. - : Mary Ann Liebert Inc. - 1547-3287 .- 1557-8534. ; 25:14, s. 1035-1049
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Research review (peer-reviewed)abstract
- Our concept of cell reprogramming and cell plasticity has evolved since John Gurdon transferred the nucleus of a completely differentiated cell into an enucleated Xenopus laevis egg, thereby generating embryos that developed into tadpoles. More recently, induced expression of transcription factors, oct4, sox2, klf4, and c-myc has evidenced the plasticity of the genome to change the expression program and cell phenotype by driving differentiated cells to the pluripotent state. Beyond these milestone achievements, research in artificial cell reprogramming has been focused on other molecules that are different than transcription factors. Among the candidate molecules, microRNAs (miRNAs) stand out due to their potential to control the levels of proteins that are involved in cellular processes such as self-renewal, proliferation, and differentiation. Here, we review the role of miRNAs in the maintenance and differentiation of mesenchymal stem cells, epimorphic regeneration, and somatic cell reprogramming to induced pluripotent stem cells.
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| 2. |
- Zamora, Juan Carlos, et al.
(author)
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Considerations and consequences of allowing DNA sequence data as types of fungal taxa
- 2018
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In: IMA Fungus. - : INT MYCOLOGICAL ASSOC. - 2210-6340 .- 2210-6359. ; 9:1, s. 167-185
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Journal article (peer-reviewed)abstract
- Nomenclatural type definitions are one of the most important concepts in biological nomenclature. Being physical objects that can be re-studied by other researchers, types permanently link taxonomy (an artificial agreement to classify biological diversity) with nomenclature (an artificial agreement to name biological diversity). Two proposals to amend the International Code of Nomenclature for algae, fungi, and plants (ICN), allowing DNA sequences alone (of any region and extent) to serve as types of taxon names for voucherless fungi (mainly putative taxa from environmental DNA sequences), have been submitted to be voted on at the 11th International Mycological Congress (Puerto Rico, July 2018). We consider various genetic processes affecting the distribution of alleles among taxa and find that alleles may not consistently and uniquely represent the species within which they are contained. Should the proposals be accepted, the meaning of nomenclatural types would change in a fundamental way from physical objects as sources of data to the data themselves. Such changes are conducive to irreproducible science, the potential typification on artefactual data, and massive creation of names with low information content, ultimately causing nomenclatural instability and unnecessary work for future researchers that would stall future explorations of fungal diversity. We conclude that the acceptance of DNA sequences alone as types of names of taxa, under the terms used in the current proposals, is unnecessary and would not solve the problem of naming putative taxa known only from DNA sequences in a scientifically defensible way. As an alternative, we highlight the use of formulas for naming putative taxa (candidate taxa) that do not require any modification of the ICN.
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| 3. |
- Abelev, Betty, et al.
(author)
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Long-range angular correlations on the near and away side in p-Pb collisions at root S-NN=5.02 TeV
- 2013
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In: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 719:1-3, s. 29-41
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Journal article (peer-reviewed)abstract
- Angular correlations between charged trigger and associated particles are measured by the ALICE detector in p-Pb collisions at a nucleon-nucleon centre-of-mass energy of 5.02 TeV for transverse momentum ranges within 0.5 < P-T,P-assoc < P-T,P-trig < 4 GeV/c. The correlations are measured over two units of pseudorapidity and full azimuthal angle in different intervals of event multiplicity, and expressed as associated yield per trigger particle. Two long-range ridge-like structures, one on the near side and one on the away side, are observed when the per-trigger yield obtained in low-multiplicity events is subtracted from the one in high-multiplicity events. The excess on the near-side is qualitatively similar to that recently reported by the CMS Collaboration, while the excess on the away-side is reported for the first time. The two-ridge structure projected onto azimuthal angle is quantified with the second and third Fourier coefficients as well as by near-side and away-side yields and widths. The yields on the near side and on the away side are equal within the uncertainties for all studied event multiplicity and p(T) bins, and the widths show no significant evolution with event multiplicity or p(T). These findings suggest that the near-side ridge is accompanied by an essentially identical away-side ridge. (c) 2013 CERN. Published by Elsevier B.V. All rights reserved.
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| 4. |
- Caballero-Pérez, Juan, et al.
(author)
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Transcriptional landscapes of Axolotl (Ambystoma mexicanum)
- 2018
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In: Developmental Biology. - : Elsevier. - 0012-1606 .- 1095-564X. ; 433:2, s. 227-239
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Journal article (peer-reviewed)abstract
- The axolotl (Ambystoma mexicanum) is the vertebrate model system with the highest regeneration capacity. Experimental tools established over the past 100 years have been fundamental to start unraveling the cellular and molecular basis of tissue and limb regeneration. In the absence of a reference genome for the Axolotl, transcriptomic analysis become fundamental to understand the genetic basis of regeneration.Here we present one of the most diverse transcriptomic data sets for Axolotl by profiling coding and non coding RNAs from diverse tissues. We reconstructed a population of 115,906 putative protein coding mRNAs as full ORFs (including isoforms). We also identified 352 conserved miRNAs and 297 novel putative mature miRNAs.Systematic enrichment analysis of gene expression allowed us to identify tissue-specific protein-coding transcripts. We also found putative novel and conserved microRNAs which potentially target mRNAs which are reported as important disease candidates in heart and liver.
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| 5. |
- Abelev, Betty, et al.
(author)
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Measurement of prompt J/psi and beauty hadron production cross sections at mid-rapidity in pp collisions at root s=7 TeV
- 2012
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In: Journal of High Energy Physics. - 1029-8479. ; :11
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Journal article (peer-reviewed)abstract
- The ALICE experiment at the LHC has studied J/psi production at mid-rapidity in pp collisions at root s = 7 TeV through its electron pair decay on a data sample corresponding to an integrated luminosity L-int = 5.6 nb(-1). The fraction of J/psi from the decay of long-lived beauty hadrons was determined for J/psi candidates with transverse momentum p(t) > 1,3 GeV/c and rapidity vertical bar y vertical bar < 0.9. The cross section for prompt J/psi mesons, i.e. directly produced J/psi and prompt decays of heavier charmonium states such as the psi(2S) and chi(c) resonances, is sigma(prompt J/psi) (p(t) > 1.3 GeV/c, vertical bar y vertical bar < 0.9) = 8.3 +/- 0.8(stat.) +/- 1.1 (syst.)(-1.4)(+1.5) (syst. pol.) mu b. The cross section for the production of b-hadrons decaying to J/psi with p(t) > 1.3 GeV/c and vertical bar y vertical bar < 0.9 is a sigma(J/psi <- hB) (p(t) > 1.3 GeV/c, vertical bar y vertical bar < 0.9) = 1.46 +/- 0.38 (stat.)(-0.32)(+0.26) (syst.) mu b. The results are compared to QCD model predictions. The shape of the p(t) and y distributions of b-quarks predicted by perturbative QCD model calculations are used to extrapolate the measured cross section to derive the b (b) over bar pair total cross section and d sigma/dy at mid-rapidity.
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| 6. |
- Abelev, Betty, et al.
(author)
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Underlying Event measurements in pp collisions at root s=0.9 and 7 TeV with the ALICE experiment at the LHC
- 2012
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In: Journal of High Energy Physics. - 1029-8479. ; :7
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Journal article (peer-reviewed)abstract
- We present measurements of Underlying Event observables in pp collisions at root s = 0 : 9 and 7 TeV. The analysis is performed as a function of the highest charged-particle transverse momentum p(T),L-T in the event. Different regions are defined with respect to the azimuthal direction of the leading (highest transverse momentum) track: Toward, Transverse and Away. The Toward and Away regions collect the fragmentation products of the hardest partonic interaction. The Transverse region is expected to be most sensitive to the Underlying Event activity. The study is performed with charged particles above three different p(T) thresholds: 0.15, 0.5 and 1.0 GeV/c. In the Transverse region we observe an increase in the multiplicity of a factor 2-3 between the lower and higher collision energies, depending on the track p(T) threshold considered. Data are compared to PYTHIA 6.4, PYTHIA 8.1 and PHOJET. On average, all models considered underestimate the multiplicity and summed p(T) in the Transverse region by about 10-30%.
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| 7. |
- Cruz-Ramírez, Alfredo, et al.
(author)
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A Bistable Circuit Involving SCARECROW-RETINOBLASTOMA Integrates Cues to Inform Asymmetric Stem Cell Division
- 2012
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In: Cell. - : Elsevier. - 0092-8674 .- 1097-4172. ; 150:5, s. 1002-1015
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Journal article (peer-reviewed)abstract
- In plants, where cells cannot migrate, asymmetric cell divisions (ACDs) must be confined to the appropriate spatial context. We investigate tissue-generating asymmetric divisions in a stem cell daughter within the Arabidopsis root. Spatial restriction of these divisions requires physical binding of the stem cell regulator SCARECROW (SCR) by the RETINOBLASTOM-RELATED (RBR) protein. In the stem cell niche, SCR activity is counteracted by phosphorylation of RBR through a cyclinD6;1-CDK complex. This cyclin is itself under transcriptional control of SCR and its partner SHORT ROOT (SHR), creating a robust bistable circuit with either high or low SHR-SCR complex activity. Auxin biases this circuit by promoting CYCD6;1 transcription. Mathematical modeling shows that ACDs are only switched on after integration of radial and longitudinal information, determined by SHR and auxin distribution, respectively. Coupling of cell-cycle progression to protein degradation resets the circuit, resulting in a "flip flop" that constrains asymmetric cell division to the stem cell region.
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| 8. |
- Espinal-Centeno, Annie, et al.
(author)
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Conservation analysis of core cell cycle regulators and their transcriptional behavior during limb regeneration in Ambystoma mexicanum
- 2020
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In: Mechanisms of Development. - : Elsevier. - 0925-4773 .- 1872-6356. ; 164
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Journal article (peer-reviewed)abstract
- Ambystoma mexicanum (axolotl) has been one of the major experimental models for the study of regeneration during the past 100 years. Axolotl limb regeneration takes place through a multi-stage and complex developmental process called epimorphosis that involves diverse events of cell reprogramming. Such events start with dedifferentiation of somatic cells and the proliferation of quiescent stem cells to generate a population of proliferative cells called blastema. Once the blastema reaches a mature stage, cells undergo progressive differentiation into the diverse cell lineages that will form the new limb. Such pivotal cell reprogramming phenomena depend on the fine-tuned regulation of the cell cycle in each regeneration stage, where cell populations display specific proliferative capacities and differentiation status. The axolotl genome has been fully sequenced and released recently, and diverse RNA-seq approaches have also been generated, enabling the identification and conservatory analysis of core cell cycle regulators in this species. We report here our results from such analyses and present the transcriptional behavior of key regulatory factors during axolotl limb regeneration. We also found conserved protein interactions between axolotl Cyclin Dependent Kinases 2, 4 and 6 and Cyclins type D and E. Canonical CYC-CDK interactions that play major roles in modulating cell cycle progression in eukaryotes.
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| 9. |
- Zhao, Chengsong, et al.
(author)
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XYLEM NAC DOMAIN1, an angiosperm NAC transcription factor, inhibits xylem differentiation through conserved motifs that interact with RETINOBLASTOMA-RELATED
- 2017
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In: New Phytologist. - : Wiley-Blackwell. - 0028-646X .- 1469-8137. ; 216:1, s. 76-89
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Journal article (peer-reviewed)abstract
- The Arabidopsis thaliana gene XYLEM NAC DOMAIN1 (XND1) is upregulated in xylem tracheary elements. Yet overexpression of XND1 blocks differentiation of tracheary elements. The molecular mechanism of XND1 action was investigated. Phylogenetic and motif analyses indicated that XND1 and its homologs are present only in angiosperms and possess a highly conserved C-terminal region containing linear motifs (CKII-acidic, LXCXE, E2F(TD)-like and LXCXE-mimic) predicted to interact with the cell cycle and differentiation regulator RETINOBLASTOMA-RELATED (RBR). Protein-protein interaction and functional analyses of XND1 deletion mutants were used to test the importance of RBR-interaction motifs. Deletion of either the LXCXE or the LXCXE-mimic motif reduced both the XND1-RBR interaction and XND1 efficacy as a repressor of differentiation, with loss of the LXCXE motif having the strongest negative impacts. The function of the XND1 C-terminal domain could be partially replaced by RBR fused to the N-terminal domain of XND1. XND1 also transactivated gene expression in yeast and plants. The properties of XND1, a transactivator that depends on multiple linear RBR-interaction motifs to inhibit differentiation, have not previously been described for a plant protein. XND1 harbors an apparently angiosperm-specific combination of interaction motifs potentially linking the general differentiation regulator RBR with a xylem-specific pathway for inhibition of differentiation.
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| 10. |
- Ötvös, Krisztina, et al.
(author)
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Pickle recruits retinoblastoma related 1 to control lateral root formation in arabidopsis
- 2021
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In: International Journal of Molecular Sciences. - : MDPI. - 1661-6596 .- 1422-0067. ; 22:8
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Journal article (peer-reviewed)abstract
- Lateral root (LR) formation is an example of a plant post-embryonic organogenesis event. LRs are issued from non-dividing cells entering consecutive steps of formative divisions, proliferation and elongation. The chromatin remodeling protein PICKLE (PKL) negatively regulates auxin-mediated LR formation through a mechanism that is not yet known. Here we show that PKL interacts with RETINOBLASTOMA-RELATED 1 (RBR1) to repress the LATERAL ORGAN BOUNDARIES-DOMAIN 16 (LBD16) promoter activity. Since LBD16 function is required for the formative division of LR founder cells, repression mediated by the PKL–RBR1 complex negatively regulates formative division and LR formation. Inhibition of LR formation by PKL–RBR1 is counteracted by auxin, indicating that, in addition to auxin-mediated transcriptional responses, the fine-tuned process of LR formation is also controlled at the chromatin level in an auxin-signaling dependent manner.
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