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Z Szilagyi

Publications and source records attributed to Z Szilagyi.

7 recordsLinked to original sources
PubMed2005

Characterisation of two novel fork-head gene homologues of Schizosaccharomyces pombe: their involvement in cell cycle and sexual differentiation.

The fork-head type transcription factors are a class of regulators that function in a broad spectrum of cellular and developmental processes in many species ranging from yeasts to human. Previous data on yeast fork-head genes suggested roles for these regulators in the control of cell division, sexual differentiation and development. The genome of Schizosaccharomyces pombe has four genes that code for proteins containing fork-head domains (FKH), two of which have been characterised. Here we describe the remaining two genes, fhl1 and fkh2, that code for proteins containing fork-head-associated domains (FHA) besides their FKHs. Neither of them is essential for viability, although the deletion of either fhl1 (putative homologue of Saccharomyces cerevisiae FHL1) or fkh2 (similar to FKH1 and FKH2 of S. cerevisiae) reduced the growth rate and caused an extension of cell length due to delayed G2-to-M transition. Occasionally, multiseptate cells were also produced, indicating the involvement of fhl1 and fkh2 in efficient septum cleavage. The fkh2Delta cells were slightly more sensitive than the wild-type cells to certain environmental stresses, showed reduced fertility and occasional deficiencies in meiosis II, indicating that fkh2 might also act in stress response and sexual differentiation.

Amino Acid Sequence↗
PubMed2003

Towards sub-0.5 A electron beams.

In the 4 years since the previous meeting in the SALSA series, aberration correction has progressed from a promising concept to a powerful research tool. We summarize the factors that have enabled 100-120kV scanning transmission electron microscopes to achieve sub-A resolution, and to increase the current available in an atom-sized probe by a factor of 10 and more. Once C(s) is corrected, fifth-order spherical aberration (C(5)) and chromatic aberration (C(c)) pose new limits on resolution. We describe a quadrupole/octupole corrector of a new design, which will correct all fifth-order aberrations while introducing less than 0.2mm of additional C(c). Coupled to an optimized STEM column, the new corrector promises to lead to routine sub-A electron probes at 100kV, and to sub-0.5A probes at higher operating voltages.

Journal Article↗
PubMed2002

The Schizosaccharomyces pombe genes sep10 and sep11 encode putative general transcriptional regulators involved in multiple cellular processes.

We have previously described the genetic analysis of eleven complementation groups ( sep6- sep16) defined by Schizosaccharomyces pombe mutants that are defective in cell separation and sexual differentiation. Here we report on the cloning and characterisation of two members of this set, sep10 and sep11. Sequencing of the full-length sep10 revealed a continuous ORF that encodes a conserved protein with possible functions in general transcriptional regulation. The coding region of sep11 is interrupted by introns and the putative s ep11 protein shows no sequence similarity with known proteins of other species. Disruption of each gene causes temperature sensitivity. Simultaneous disruption of both genes is lethal, demonstrating that sep10 and sep11 perform related, overlapping functions. Overexpression of aff1/ste11, a pivotal regulator of sexual development, suppresses the sterility of sep10 (-) cells, which suggests that sep10 is needed for the activity of aff1/ste11.

Amino Acid Sequence↗
PubMed2002

Marker construction and cloning of a cut1-like sequence with ARS activity in the fission yeast Schizosaccharomyces japonicus.

The dimorphic fission yeast Schizosaccharomyces japonicus has proved to be an excellent experimental model for the investigation of the eukaryotic cell. Here we show that it has a haplontic life cycle, in which the diploid phase is confined to the zygote. To make it amenable to genetic and molecular analysis, we generated genetic markers and cloned a genomic sequence which acts as ars when integrated into a plasmid. Diploids suitable for testing complementation and recombination between markers can be formed by protoplast fusion. The complementation tests and the recombination frequencies determined in octads of spores identified 28 non-allelic groups (genes) of mutations of the auxotrophic and mycelium-negative mutants. Two groups of linked markers were also identified. The cloned fragment, which expresses ars activity, encodes a putative amino acid sequence highly similar to a conserved domain of proteins Cut1 (Schizosaccharomyces pombe), BimB (Aspergillus nidulans) and Esp1 (Saccharomyces cerevisiae).

Amino Acid Sequence↗
PubMed1999

Eleven novel sep genes of Schizosaccharomyces pombe required for efficient cell separation and sexual differentiation.

Genetic analysis of 20 sterile mutants prone to form hyphae revealed 11 novel ste genes (sep6 to sep16) of Schizosaccharomyces pombe. None of the mutants was completely mycelial. Most mutants formed branching hyphae and showed normal septation. Aberrant septal structures and actin distribution were seen only at 36 degrees C. sep9-307, sep14-576 and sep15-598 showed genetic interactions with sep1-1, a mutation in a forkhead transcription factor homologue. Additional genetic interactions were detected between sep6-194, sep15-598 and cdc16-116, a mutant allele of an anaphase modulator of p34cdc2. sep9-307 and sep15-598 caused dikaryosis in wee1- background. In mating and sporulation tests, sep6-, sep7-, sep9-, sep10-, sep11- and sep15- proved to be defective in conjugation only, whereas sep8-, sep13- and sep16- were also defective in meiosis-sporulation. sep12- and sep14- were only partially sterile. All mutants could produce M-factor but sep8-, sep11-, sep15- and sep16- were defective in P-factor production. The mutations in sep8, sep11 and sep16 suppressed the pat1-114-driven meiosis. All mutants were sensitive to the presence of higher concentrations of chloride in the medium and to short heat shocks. The diversity of the mutant phenotypes and the pleiotropic effects of the mutations suggest that these sep genes might act in, or interact with, a multiple overlapping network of regulatory modules.

Actins↗
PubMed1993

The role of reactive oxygen intermediates in the pathogenesis of chronic apical periodontitis.

The level of malondialdehyde, a stable end product of lipid peroxidation induced by reactive oxygen intermediates and the activity of two potent antioxidant enzymes, superoxide dismutase and glutathione peroxidase, was investigated in tissue homogenates of 22 surgical periapical granuloma specimens. Malondialdehyde levels were significantly higher and glutathione peroxidase activity was significantly lower in periapical granuloma samples than in healthy gingival tissue homogenates, which were used as controls. The activity of superoxide dismutase was similar in periapical granuloma and in control samples. Our results indicate an altered balance between the production and the elimination of toxic oxygen metabolites in chronic apical periodontitis. We hypothesize that reactive oxygen intermediates, which are being produced by activated phagocytic cells abundantly present in periapical granulomas, can contribute to periapical tissue injury and bone loss in this disease.

Adult↗