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Elp3 and Dph3 of Schizosaccharomyces pombe mediate cellular stress responses through tRNALys UUU modifications
Efficient protein synthesis in eukaryotes requires diphthamide modification of translation elongation factor eEF2 and wobble uridine modifications of tRNAs. In higher eukaryotes, these processes are important for preventing neurological and developmental defects and cancer. In this study, we used Schizosaccharomyces pombe as a model to analyse mutants defective in eEF2 modification (dph1Î), in tRNA modifications (elp3Î), or both (dph3Î) for sensitivity to cytotoxic agents and thermal stress. The dph3Î and elp3Î mutants were sensitive to a range of drugs and had growth defects at low temperature. dph3Î was epistatic with dph1Î for sensitivity to hydroxyurea and methyl methanesulfonate, and with elp3Î for methyl methanesulfonate and growth at 16 °C. The dph1Î and dph3Î deletions rescued growth defects of elp3Î in response to thiabendazole and at 37 °C. Elevated tRNALys UUU levels suppressed the elp3Î phenotypes and some of the dph3Î phenotypes, indicating that lack of tRNALys UUU modifications were responsible. Furthermore, we found positive genetic interactions of elp3Î and dph3Î with sty1Î and atf1Î, indicating that Elp3/Dph3-dependent tRNA modifications are important for efficient biosynthesis of key factors required for accurate responses to cytotoxic stress conditions
Genetic and cytological characterization of the RecA-homologous proteins Rad51 and Dmc1 of Schizosaccharomyces pombe
The Schizosaccharomyces pombe rad51 + and dmc1 + genes code for homologues of the Escherichia coli recombination protein RecA. Deletion of rad51 + causes slow growth, retardation of cell division and a decrease in viability. rad51Î cells have a defect in mating-type switching. The DNA modification at the mating-type locus required for mating-type switching contributes to slow growth in the rad51 mutant. Cell mating is reduced in crosses homozygous for rad51Î. Ectopic expression of the dmc1 + gene allowed us to demonstrate that the reduction in meiotic recombination in dmc1 mutants is not caused by a disturbance of rad24 expression from the dmc1-rad24 bicistronic RNA. We describe the functional defects of terminally epitope-tagged Dmc1 and Rad51 and discuss it in terms of protein interaction. Presumptive Rad51 and Dmc1 foci were detected on spreads of meiotic chromati
Netzwerk Ăkologische PflanzenzĂŒchtung: Möglichkeiten und Methoden, Grenzen zwischen klassischen und âgentechnischenâ ZĂŒchtungsmethoden, partizipative PflanzenzĂŒchtung
Das Netzwerk Ăkologische PflanzenzĂŒchtung hatte zum Ziel, die verschiedenen Akteure aus dem Sektor der ökologischen PflanzenzĂŒchtung besser zu vernetzen und zu koordinieren sowie den Austausch von Ideen und Informationen zu ermöglichen. Das Projekt wurde vor dem Hintergrund der starken AbhĂ€ngigkeit des ökologischen Anbaus von konventionell gezĂŒchteten Sorten sowie dem stetig zunehmenden Einsatz molekularbiologischer Techniken in der Pflanzenzucht konzipiert. Auf Grund dieser Entwicklungen bestand ein groĂer Bedarf sowohl an Informationen ĂŒber ZĂŒchtungstechniken und gemeinsamem Austausch hierzu als auch konkret an besser auf die Bedingungen des Ăkolandbaus abgestimmtem Vermehrungsmaterial.
In den ĂŒber das Netzwerk ausgerichteten Workshops traten ZĂŒchter, Anbauer, Berater, Vertreter der verschiedenen AnbauverbĂ€nde und Wissenschaftler in einen gemeinsamen Dialog. Durch die Einbeziehung aller Akteure konnte das Projekt in vielen Bereichen einen Anschub oder Beitrag zur Weiterentwicklung der ökologischen PflanzenzĂŒchtung leisten. In der Projektlaufzeit erfolgte unter anderem eine deutlichere Positionierung der AnbauverbĂ€nde hinsichtlich bestimmter ZĂŒchtungstechniken sowie eine diesbezĂŒgliche Sensibilisierung. Daneben wurden Diskussionen und Entwicklungen zur besseren BĂŒndelung und Finanzierung ökologischer ZĂŒchtungsaktivitĂ€ten sowie die GrĂŒndung neuer ökologischer ZĂŒchtungsinitiativen und verbandsinterner ZĂŒchtungsforen angeregt.
Das Projekt verstand sich in erster Linie als Networking Projekt, um in den Bereichen Austausch von Ideen und Informationen sowie Bereitstellung von geeignetem Vermehrungsmaterial Fortschritte zu erzielen. Neben den Workshops wurde es durch Praxisversuche flankiert um Sorten aus den Bereichen Ackerkulturen, GemĂŒsekulturen, Obstkulturen und Reben unter den Bedingungen des ökologischen Landbaus zu prĂŒfen und fĂŒr die Praxis bei Feldtagen zu demonstrieren. Die Versuche und Demonstrationen konnten unter anderem dazu beitragen, dass Praktiker zum Wintererbsenanbau animiert wurden, eine ökologisch gezĂŒchtete Speisegerstensorte sowie zwei Wintererbsensorten zur Anmeldung gebracht wurden. Durch den Versuchsbau konnten auĂerdem mehrere GemĂŒsesorten angemeldet, eine schorfresistente Apfelsorte etabliert und die Bekanntheit und AnbauflĂ€che von pilzwiderstandsfĂ€higen Rebsorten (Piwi) gesteigert werden. SchlieĂlich wurden Fragestellungen in weitere Forschungsprojekte eingespeist und wichtige Impulse fĂŒr die ökologisch-partizipative PflanzenzĂŒchtung in Deutschland gesetzt
Deoxynucleoside salvage in fission yeast allows rescue of ribonucleotide reductase deficiency but not Spd1-Mediated inhibition of replication
In fission yeast, the small, intrinsically disordered protein S-phase delaying protein 1 (Spd1) blocks DNA replication and causes checkpoint activation at least in part, by inhibiting the enzyme ribonucleotide reductase, which is responsible for the synthesis of DNA building blocks. The CRL4Cdt2 E3 ubiquitin ligase mediates degradation of Spd1 and the related protein Spd2 at S phase of the cell cycle. We have generated a conditional allele of CRL4Cdt2, by expressing the highly unstable substrate-recruiting protein Cdt2 from a repressible promoter. Unlike Spd1, Spd2 does not regulate deoxynucleotide triphosphate (dNTP) pools; yet we find that Spd1 and Spd2 together inhibit DNA replication upon Cdt2 depletion. To directly test whether this block of replication was solely due to insufficient dNTP levels, we established a deoxy-nucleotide salvage pathway in fission yeast by expressing the human equilibrative nucleoside transporter 1 (hENT1) and the Drosophila deoxynucleoside kinase. We present evidence that this salvage pathway is functional, as 2 ”M of deoxynucleosides in the culture medium is able to rescue the growth of two different temperature-sensitive alleles controlling ribonucleotide reductase. However, salvage completely failed to rescue S phase delay, checkpoint activation, and damage sensitivity, which was caused by CRL4Cdt2 inactivation, suggesting that Spd1âin addition to repressing dNTP synthesisâtogether with Spd2, can inhibit other replication functions. We propose that this inhibition works at the point of the replication clamp proliferating cell nuclear antigen, a co-factor for DNA replication
Investigation of Salt Tolerance Mechanisms across a Root Developmental Gradient in Almond Rootstocks
The intensive use of groundwater in agriculture under the current climate conditions leads to acceleration of soil salinization. Given that almond is a salt-sensitive crop, selection of salt-tolerant rootstocks can help maintain productivity under salinity stress. Selection for tolerant rootstocks at an early growth stage can reduce the investment of time and resources. However, salinity-sensitive markers and salinity tolerance mechanisms of almond species to assist this selection process are largely unknown. We established a microscopy-based approach to investigate mechanisms of stress tolerance in and identified cellular, root anatomical, and molecular traits associated with rootstocks exhibiting salt tolerance. We characterized three almond rootstocks: Empyrean-1 (E1), Controller-5 (C5), and Krymsk-86 (K86). Based on cellular and molecular evidence, our results show that E1 has a higher capacity for salt exclusion by a combination of upregulating ion transporter expression and enhanced deposition of suberin and lignin in the root apoplastic barriers, exodermis, and endodermis, in response to salt stress. Expression analyses revealed differential regulation of cation transporters, stress signaling, and biopolymer synthesis genes in the different rootstocks. This foundational study reveals the mechanisms of salinity tolerance in almond rootstocks from cellular and structural perspectives across a root developmental gradient and provides insights for future screens targeting stress response
Regulation of ribonucleotide reductase by Spd1 involves multiple mechanisms
The correct levels of deoxyribonucleotide triphosphates and their relative abundance are important to maintain genomic integrity. Ribonucleotide reductase (RNR) regulation is complex and multifaceted. RNR is regulated allosterically by two nucleotide-binding sites, by transcriptional control, and by small inhibitory proteins that associate with the R1 catalytic subunit. In addition, the subcellular localization of the R2 subunit is regulated through the cell cycle and in response to DNA damage. We show that the fission yeast small RNR inhibitor Spd1 is intrinsically disordered and regulates R2 nuclear import, as predicted by its relationship to Saccharomyces cerevisiae Dif1. We demonstrate that Spd1 can interact with both R1 and R2, and show that the major restraint of RNR in vivo by Spd1 is unrelated to R2 subcellular localization. Finally, we identify a new behavior for RNR complexes that potentially provides yet another mechanism to regulate dNTP synthesis via modulation of RNR complex architecture
Vegard Relation and Raman Band Reference Data Generated from Bulk Crystals of Kesterite-Phase Composition Series Cu2ZnSnS4xSe4â4x (CZTSSe, 0 †x †1)
Solid solutions in the series Cu2ZnSnS4xSe4â4x (CZTSSe) are of interest for PV applications. The purpose of this work was to grow bulk crystalline samples over the entire composition range to allow the Vegard relation (lattice parameter variation with composition) and the systematic behavior of Raman bands to be defined to generate reference data. Samples with 0 †x †1 were synthesized from the elements and grown into crystalline form from solution in either KCl/NaCl eutectic or elemental Sn. Details of the crystal growth outcomes, including the use of a quartz seed plate to make thick film samples, are described. Ordered kesterite-type material was formed upon crystallization, and X-ray diffraction demonstrated linear Vegard relationships, with the lattice parameters varying with composition as a (Ă
) = â0.268(3)x + 5.6949(17) and c (Ă
) = â0.516(6)x + 11.345(3). Raman spectroscopy yielded two dominant peaks, these being kesterite A modes associated with the Se and S modes in CZTSe and CZTS. These varied in wavenumber linearly as ÏCZTSe (cmâ1) = (44.6 ± 1.6)x + (194.6 ± 0.8) and ÏCZTS (cmâ1) = (7.1 ± 1.3)x + (329.0 ± 0.8). Crystallization was also shown to promote ordering. The variation of lattice parameters with composition exhibited significant differences from those observed in previous studies. Also, while the Raman S mode behavior differed from previous reports, the Se modes were similar. These differences are discussed
Wbp2 is required for normal glutamatergic synapses in the cochlea and is crucial for hearing
WBP2 encodes the WW domain-binding protein 2 that acts as a
transcriptional coactivator for estrogen receptor a (ESR1) and
progesterone receptor (PGR). We reported that the loss of Wbp2
expression leads to progressive high-frequency hearing loss in
mouse, as well as in two deaf children, each carrying two different
variants in the WBP2 gene. The earliest abnormality we detect in
Wbp2-deficient mice is a primary defect at inner hair cell afferent
synapses. This study defines a new gene involved in the molecular
pathway linking hearing impairment to hormonal signalling and
provides new therapeutic targets
Dimethylarginine metabolism during acute and chronic rejection of rat renal allografts
Background. Dimethylarginines are inhibitors of NO synthesis and are involved in the pathogenesis of vascular diseases. In this study, we ask the question if asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA) levels change during fatal and reversible acute rejection, and contribute to the pathogenesis of chronic vasculopathy
A Time Projection Chamber with GEM-Based Readout
For the International Large Detector concept at the planned International
Linear Collider, the use of time projection chambers (TPC) with micro-pattern
gas detector readout as the main tracking detector is investigated. In this
paper, results from a prototype TPC, placed in a 1 T solenoidal field and read
out with three independent GEM-based readout modules, are reported. The TPC was
exposed to a 6 GeV electron beam at the DESY II synchrotron. The efficiency for
reconstructing hits, the measurement of the drift velocity, the space point
resolution and the control of field inhomogeneities are presented.Comment: 22 pages, 19 figure
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