Viesturs Simanis

Bio: Viesturs Simanis is an academic researcher from ISREC. The author has contributed to research in topics: Schizosaccharomyces pombe & Mitosis. The author has an hindex of 40, co-authored 89 publications receiving 6039 citations. Previous affiliations of Viesturs Simanis include École Polytechnique Fédérale de Lausanne & Lincoln's Inn.

The dmf1/mid1 gene is essential for correct positioning of the division septum in fission yeast.

Abstract: Little is known about the mechanisms that establish the position of the division plane in eukaryotic cells. Wild-type fission yeast cells divide by forming a septum in the middle of the cell at the end of mitosis. Dmf1 mutants complete mitosis and initiate septum formation, but the septa that form are positioned at random locations and angles in the cell, rather than in the middle. We have cloned the dmf1 gene as a suppressor of the cdc7-24 mutant. The dmf1 mutant is allelic with mid1. The gene encodes a novel protein containing a putative nuclear localization signal, and a carboxy-terminal PH domain. In wild-type cells, Dmf1p is nuclear during interphase, and relocates to form a medial ring at the cell cortex coincident with the onset of mitosis. This relocalization occurs before formation of the actin ring and is associated with increased phosphorylation of Dmf1p. The Dmf1p ring can be formed in the absence of an actin ring, but depends on some of the genes required for actin ring formation. When the septum is completed and the cells separate, Dmf1p staining is once again nuclear. These data implicate Dmf1p as an important element in assuring correct placement of the division septum in Schizosaccharomyces pombe cells.

Noninvasive characterization of the fission yeast cell cycle by monitoring dry mass with digital holographic microscopy

Abstract: Digital holography microscopy (DHM) is an optical technique which provides phase images yielding quantitative information about cell structure and cellular dynamics. Furthermore, the quantitative phase images allow the derivation of other parameters, including dry mass production, density, and spatial distribution. We have applied DHM to study the dry mass production rate and the dry mass surface density in wild-type and mutant fission yeast cells. Our study demonstrates the applicability of DHM as a tool for label-free quantitative analysis of the cell cycle and opens the possibility for its use in high-throughput screening.

The Ubiquitin-Proteasome Proteolytic Pathway: Destruction for the Sake of Construction

Abstract: Between the 1960s and 1980s, most life scientists focused their attention on studies of nucleic acids and the translation of the coded information. Protein degradation was a neglected area, conside...

Molecular genetic analysis of fission yeast Schizosaccharomyces pombe.

Abstract: Publisher Summary This chapter describes techniques concerned with classical and molecular genetics, cell biology, and biochemistry that can be used with Schizosaccharomyces pombe . Conjugation and sporulation cannot take place in S. pombe except under conditions of nutrient starvation. ME medium is generally used for genetic crosses. To cross two strains, a loopful of h – and a loopful of h + are mixed together on a ME plate. The cross is left to dry and is then incubated below 30°, as conjugation is severely reduced above this temperature. Fully formed four-spore asci can be seen after 2–3 days of incubation. A 2 day-old cross is usually used for tetrad analysis. Using a 3-day-old cross, one can check for the presence of asci under the light microscope. Random spore analysis allows many more spores to be examined than in tetrad analysis, and in this way recombination mapping and strain construction can be carried out. Diploid cells arise spontaneously in most S. pombe strains, this characteristic can be used to isolate homozygous diploids of any strain. For mutagenesis of yeast strains, ethylmethane sulfonate (EMS) and nitrosoguanidine is used.

Universal control mechanism regulating onset of M-phase

Abstract: The onset of M-phase is regulated by a mechanism common to all eukaryotic cells. Entry into M-phase is determined by activation of the p34cdc2 protein kinase which requires p34cdc2 dephosphorylation and association with cyclin.

Mitotic kinases as regulators of cell division and its checkpoints

Abstract: Mitosis and cytokinesis are undoubtedly the most spectacular parts of the cell cycle. Errors in the choreography of these processes can lead to aneuploidy or genetic instability, fostering cell death or disease. Here, I give an overview of the many mitotic kinases that regulate cell division and the fidelity of chromosome transmission.