Cdc2 activation in fission yeast depends on Mcs6 and Csk1, two partially redundant Cdk-activating kinases (CAKs).

Cyclin-dependent kinases (Cdks) are fully active only when phosphorylated by a Cdk-activating kinase (CAK) [1]. Metazoan CAK is itself a Cdk, Cdk7, whereas the CAK of Saccharomyces cerevisiae is a distinct enzyme unrelated to Cdks [1]. The Mcs6-Mcs2 complex of Schizosaccharomyces pombe is a putative CAK related to the metazoan enzyme [2] [3]. Although the loss of Mcs6 is lethal, it results in a phenotype that is inconsistent with a failure to activate Cdc2, the major Cdk in S. pombe [3]. We therefore tested the ability of Csk1, a putative regulator of Mcs6 [4], to activate Cdk-cyclin complexes in vitro. Csk1 activated both the monomeric and the Mcs2-bound forms of Mcs6. Surprisingly, Csk1 also activated Cdc2 in complexes with either Cdc13 or Cig2 cyclins. When a double mutant carrying a csk1 deletion and a temperature-sensitive mcs6 allele was incubated at the restrictive temperature, Cdc2 was not activated and the cells underwent a cell division arrest prior to mitosis. Cdc2-cyclin complexes isolated from the arrested cells could be activated in vitro by recombinant CAK, whereas complexes from wild-type cells or either of the single mutants were refractory to activation. Thus, fission yeast contains two partially redundant CAKs: the Mcs6-Mcs2 complex and Csk1. Inactivation of both CAKs is necessary and sufficient to prevent Cdc2 activation and cause a cell-cycle arrest. Mcs6, which is essential, may therefore have required functions other than Cdk activation.

Disruption of six unknown open reading frames from Saccharomyces cerevisiae reveals two genes involved in vacuolar morphogenesis and one gene required for sporulation.

In this report we describe the construction and basic phenotypic analysis of deletion mutants in six open reading frames (ORFs) of unknown function from the yeast Saccharomyces cerevisiae. Using the dominant kanMX marker and polymerase chain reaction (PCR) methods, deletion cassettes were constructed for five ORFs (YNL099c, YNL100w, YNL101w, YNL106c and YNL242w) located on chromosome XIV and one ORF (YOR109w) located on chromosome XV. The recovery of viable haploid deletant strains among the meiotic products of heterozygous deletants for each ORF demonstrated that none of the analysed ORFs was essential. With the exception of YNL242w, no alterations in growth characteristics or mating and sporulation efficiencies associated with deletion of the ORFs were observed. Homozygous diploid ynl242w delta cells obtained in three different genetic backgrounds were unable to sporulate, indicating that the product of this ORF is required for sporulation. Complementation of the sporulation defect by the cognate gene clone confirmed this observation. YNL106c and YOR109w are very similar and show strong sequence homology with a mammalian phosphatidylinositol-phosphate 5-phosphatase, synaptojanin, known to be involved in synaptic vesicle cycling. Strains bearing single and double deletions of YNL106c and YOR109w were seen to display abnormal vacuolar morphologies of varying degrees. Complementation tests indicated that YNL106c and YOR109w are redundant genes.

Melanoma primario de esófago / Malignant melanoma of the esophagus: MRI findings

Se presenta el caso de un melanoma melanótico primario de esófago confirmado histológicamente, con metástasis ganglionares y pulmonar, cuyos hallazgos mediante imágenes de resonancia magnética (RM), muestran la señal de intensidad típica en T1 de esta patología

Melanoma primario de esófago / Malignant melanoma of the esophagus: MRI findings

Se presenta el caso de un melanoma melanótico primario de esófago confirmado histológicamente, con metástasis ganglionares y pulmonar, cuyos hallazgos mediante imágenes de resonancia magnética (RM), muestran la señal de intensidad típica en T1 de esta patología (AU)

The sequence of a 20.3 kb DNA fragment from the left arm of Saccharomyces cerevisiae chromosome IV contains the KIN28, MSS2, PHO2, POL3 and DUN1 genes, and six new open reading frames.

We report the sequence of a 20 300 bp DNA fragment from the left arm of Saccharomyces cerevisiae chromosome IV. This segment contains 13 complete open reading frames (ORFs) and part of another ORF, altogether covering 84.2% of the entire sequence, five of which correspond to the previously characterized KIN28, MSS2, PHO2, POL3/CDC2 and DUN1 genes. One putative protein, D2358p, shares considerable homology with an O-sialoglycoprotein endopeptidase from Pasteurella haemolytica serotype A1. The putative product of D2325 contains the characteristic consensus motif of triacylglycerol lipases. D2320p and D2352p have a putative 'leucine-zipper' structure and a RNA-binding region Rnp-1 signature, respectively.

The sequence of a 17,933 bp segment of Saccharomyces cerevisiae chromosome XIV contains the RHO2, TOP2, MKT1 and END3 genes and five new open reading frames.

We report the DNA sequence of a 17,933 bp fragment from the left arm of chromosome XIV of Saccharomyces cerevisiae. Analysis of the sequence reveals the presence of ten open reading frames (ORFs) larger than 100 codons. Four of these were previously identified as genes RHO2, TOP2, MKT1 and END3. Additionally, the NH2 end coding region of PMS1 is found in the 3' end of the sequence. No significant homology to any known protein has been found for the other five ORFs.

The sequence of a 21.3 kb DNA fragment from the left arm of yeast chromosome XIV reveals LEU4, MET4, POL1, RAS2, and six new open reading frames.

The nucleotide sequence of a fragment of 21 308 bp from the left arm of Saccharomyces cerevisiae chromosome XIV has been determined. Analysis of the sequence revealed 13 open reading frames (ORFs) longer than 300 bp, four of which correspond to the previously identified genes LEU4, MET4, POL1 and RAS2. One putative protein, N2160, shares considerable homology (32% identity) with a hypothetical protein encoded by a gene located on chromosome XV as well as with human OCRL protein (36% identity), involved in Lowe's syndrome. N2185 contains ten predicted transmembrane segments and is similar to another putative protein (YKL146) from yeast.

Neoplasias gástricas malignas: análisis radiológico retrospectivo con confirmación histológica / Malignant gastric neoplasms: retrospective radiological analysis with histological confirmation

Se realiza un análisis retrospectivo de los hallazgos radiológicos de los pacientes con diagnóstico de neoplasia gástrica maligna, operados entre enero de 1981 y diciembre de 1990, para determinar la eficacia del estudio radiológico seriado esófago gastroduodenal

Fibrohistiocitoma maligno tipo inflamatorio: patrón tomográfico atípico / Retroperitoneal malignant fibrous histiocytoma

Presentamos un caso de fibrohistiocitoma maligno tipo inflamatorio con un patrón tomográfico no descripto, mostrando valores densitométricos negativos

Neoplasias gástricas malignas: análisis radiológico retrospectivo con confirmación histológica / Malignant gastric neoplasms: retrospective radiological analysis with histological confirmation

Se realiza un análisis retrospectivo de los hallazgos radiológicos de los pacientes con diagnóstico de neoplasia gástrica maligna, operados entre enero de 1981 y diciembre de 1990, para determinar la eficacia del estudio radiológico seriado esófago gastroduodenal (AU)

Fibrohistiocitoma maligno tipo inflamatorio: patrón tomográfico atípico / Retroperitoneal malignant fibrous histiocytoma

Presentamos un caso de fibrohistiocitoma maligno tipo inflamatorio con un patrón tomográfico no descripto, mostrando valores densitométricos negativos (AU)