Deborah L. Fisher

Learn More
We show here that the state of the p34cdc2-p56cdc13 mitotic B cyclin complex determines whether a fission yeast cell undergoes S phase or mitosis. Mutants defective for p56cdc13 reset to G1 and rereplicate their DNA, while cells completely lacking the p34cdc2-p56cdc13 complex undergo multiple rounds of S phase. In contrast, formation of the p34cdc2-p56cdc13(More)
We have investigated whether Plx1, a kinase recently shown to phosphorylate cdc25c in vitro, is required for activation of cdc25c at the G2/M-phase transition of the cell cycle in Xenopus. Using immunodepletion or the mere addition of an antibody against the C terminus of Plx1, which suppressed its activation (not its activity) at G2/M, we show that Plx1(More)
MAP kinase activation occurs during meiotic maturation of oocytes from all animals, but the requirement for MAP kinase activation in reinitiation of meiosis appears to vary between different classes. In particular, it has become accepted that MAP kinase activation is necessary for progesterone-stimulated meiotic maturation of Xenopus oocytes, while this is(More)
Down-regulation of MAP kinase (MAPK) is a universal consequence of fertilization in the animal kingdom, although its role is not known. Here we show that MAPK inactivation is essential for embryos, both vertebrate and invertebrate, to enter first mitosis. Suppressing down-regulation of MAPK at fertilization, for example by constitutively activating the(More)
A hybrid gene, IPNS p /HPT orf , was constructed by placing an 850 by sequence of Cephalosporium acremonium DNA next to the 5′ end of a bacterial open reading frame, HPT orf . The sequence was obtained as an 850 by NcoI restriction fragment from the 5′ noncoding region of the C. acremonium isopenicillin N synthetase (IPNS) gene. The HPT orf was obtained(More)
Throughout oocyte maturation, and subsequently during the first mitotic cell cycle, the MAP kinase cascade and cyclin-B-Cdc2 kinase are associated with the control of cell cycle progression. Many roles have been directly or indirectly attributed to MAP kinase and its influence on cyclin-B-Cdc2 kinase in different model systems; yet a principle theme does(More)
Five cyclin-like genes, cig1, cig2/cyc17, mcs2, puc1 and cdc13, have been discovered in S. pombe to date. It is not yet clear what their functions are or even whether they are all involved with control of the cell cycle. Conflicting data for cig1 and cig2/cyc17 have obscured analysis of their function and cig1 remains largely uncharacterized, although clues(More)
Immunoprecipitation (IP) combined with matrix-assisted laser desorption ionization (MALDI) time of flight (Tof) mass spectrometry has been used to develop quantitative assays for amyloid-beta (Abeta) peptides in cerebrospinal fluid (CSF). Inclusion of (15)N labelled standard peptides allows for absolute quantification of multiple Abeta isoforms in(More)
A hybrid cefE gene was constructed by juxtaposing promoter sequences from the Penicillium chrysogenum pcbC gene to the open reading frame of the Streptomyces clavuligerus cefE gene. In S. clavuligerus the cefE gene codes for the enzyme penicillin N expandase [also known as deacetoxycephalosporin C synthetase (DAOCS)]. To insert the hybrid cefE gene into P.(More)
During Xenopus oocyte maturation, the Mos protein kinase is synthesized and activates the MAP kinase cascade. In this report, we demonstrate that the synthesis and activation of Mos are two separable processes. We find that Hsp90 function is required for activation and phosphorylation of Mos and full activation of the MAP kinase cascade. Once Mos is(More)