With the nuclear fission discovery and development of nuclear weapons in 1940s, artificial radioisotopes were introduced in the environment. This contamination is due to worldwide fallout by superficial nuclear tests realized from early 1950s to late 1970s by USA, former URSS, UK, France and China. One of theses radioisotopes that have been very studied is cesium-137. Cesium-137 has a half-life...

Compressed organic-walled microfossils attributable to five filamentous taxa, and ten coccoidal eight, (taxa originally spheroidal forms and two originally ellipsoidal, colonial forms), all having long time-ranges in the Proterozoic, have been identified in fine-grained siliciclastic sediments in cores from four bore holes cutting subsurface equivalents of the Mesoproterozoic Conselheiro Mata G...

Mating type (MAT) switching in Saccharomyces cerevisiae is initiated by a double-strand break (DSB) created at MAT by HO endonuclease. MATa cells activate the entire left arm of chromosome III; thus MATa preferentially recombines with the silent donor HML. In contrast, MAT alpha cells inactivate the left arm, including HML, and thus preferentially recombine with HMR, 100 kb to the right of MAT....

To explore the similarities and differences of regulatory circuits among budding yeasts, we characterized the role of unscheduled meiotic gene expression 6 (UME6) and a novel mating type switching pathway in Kluyveromyces lactis. We found that Ume6 was required for transcriptional silencing of the cryptic mating-type loci HML and HMRa. Ume6 acted directly at these loci by binding to the cis-re...

Cellular auto mata (CA) models have historically included only a bounded amo unt of state information. Giving cells the ab ility to send and receive a possibly unb ounded number of finite size messages creates three possible CA programming models: bounded state only, unb ounded messaging only, and both bounded state and un bound ed messaging. It is shown t hat the lat ter , alt hough computat i...

Homothallic yeasts switch cell types (mating types a and alpha) at high frequency by changing the alleles of the mating type locus, MATa and MATalpha. We have proposed in the cassette model that yeast cells contain silent MATa and MATalpha blocs ("cassettes"), copies of which can be substituted at the mating type locus for the resident information. The existence of silent cassettes was original...

There is conflicting evidence regarding the recent evolution of unemployment duration in the U.S. In this study we rely on censored quantile regression methods to analyze the changes in the US unemployment duration distribution. We employed the decomposition method proposed by Machado and Mata (2003)to disentangle the contribution of the changes generated by the covariate distribution and by th...

Seems that the news of the death of jobs for life is premature. This study uses quantile regression methods to analyze the changes in the job duration distribution in Portugal using matched employer-employee data. The paper uses a decomposition method proposed by Machado and Mata (2005) to disentangle the contribution of the compositional changes and the structural changes. Our findings indicat...

STE6 gene product is required for secretion of the lipopeptide mating pheromone a-factor by Saccharomyces cerevisiae MATa cells. Radiolabeling and immunoprecipitation, either with specific polyclonal antibodies raised against a TrpE-Ste6 fusion protein or with mAbs that recognize c-myc epitopes in fully functional epitope-tagged Ste6 derivatives, demonstrated that Ste6 is a 145-kD phosphoprotei...