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Biomedical subjects

G Alexandru

Publications and source records attributed to G Alexandru.

9 recordsLinked to original sources
PubMed2001

Phosphorylation of the cohesin subunit Scc1 by Polo/Cdc5 kinase regulates sister chromatid separation in yeast.

At the onset of anaphase, a caspase-related protease (separase) destroys the link between sister chromatids by cleaving the cohesin subunit Scc1. During most of the cell cycle, separase is kept inactive by binding to an inhibitory protein called securin. Separase activation requires proteolysis of securin, which is mediated by an ubiquitin protein ligase called the anaphase-promoting complex. Cells regulate anaphase entry by delaying securin ubiquitination until all chromosomes have attached to the mitotic spindle. Though no longer regulated by this mitotic surveillance mechanism, sister separation remains tightly cell cycle regulated in yeast mutants lacking securin. We show here that the Polo/Cdc5 kinase phosphorylates serine residues adjacent to Scc1 cleavage sites and strongly enhances their cleavage. Phosphorylation of separase recognition sites may be highly conserved and regulates sister chromatid separation independently of securin.

Amino Acid Sequence↗
PubMed1999

Sister chromatid separation and chromosome re-duplication are regulated by different mechanisms in response to spindle damage.

In yeast, anaphase entry depends on Pds1 proteolysis, while chromosome re-duplication in the subsequent S-phase involves degradation of mitotic cyclins such as Clb2. Sequential proteolysis of Pds1 and mitotic cyclins is mediated by the anaphase-promoting complex (APC). Lagging chromosomes or spindle damage are detected by surveillance mechanisms (checkpoints) which block anaphase onset, cytokinesis and DNA re-replication. Until now, the MAD and BUB genes implicated in this regulation were thought to function in a single pathway that blocks APC activity. We show that spindle damage blocks sister chromatid separation solely by inhibiting APCCdc20-dependent Pds1 proteolysis and that this process requires Mad2. Blocking APCCdh1-mediated Clb2 proteolysis and chromosome re-duplication does not require Mad2 but a different protein, Bub2. Our data imply that Mad1, Mad2, Mad3 and Bub1 regulate APCCdc20, whereas Bub2 regulates APCCdh1.

Anaphase↗
PubMedDate not supplied

Mathematical model for energy and protein balance simulation in broilers.

The authors used the empirical equations of mathematical modelling for the energy and protein balance simulation, with the view of calculating the body weight gain in broilers fed various diets. The results found by using the model were compared with the experimental data obtained by several authors. A standard deviation of +/- 1.20% and a mean error of +/- 0.28% and a mean error of +/- 0.28% which proved that the model average was a sufficient estimate of the experimental average were found. Furthermore, using the regression method, a significant correlation of variables was evidentiated.

Animal Feed↗
PubMedDate not supplied

[Circulating Salmonella serotypes isolated in the territory served by the Sanitary-antiepidemic Center of Covasna County].

During the 1967-1973 period, the authors followed up the circulation of various Salmonella serotypes and found new serotypes linked to the particular epidemiologic aspects recorded within a small district, without highly populated centers. The results showed a steady increase in the strains isolated during the last 3--4 years. Among the total 2103 strains isolated, S. panama, S. typhimurium and S. bredeney were predominant. The number of serotypes isolated varied between 10 (1968--1969) and 16 (1972). Salmonella strains were incriminated in the etiology of a fairly high proportion of the acute digestive disorders.

Gastroenteritis↗
PubMedDate not supplied

Biochemical and cytogenetical study of the mycoplasmal antigen and of the cyclophosphamide action in mammalians, in vivo. The action of some immunomodulatory antioxidants.

It was proved spectrophotometrically that Mycoplasma agalactiae antigen inoculated in vivo in sheep modifies the corresponding erythrocyte lysates reactivity toward methylene blue and neutral red and induces several types of chromosomal rearrangements. The treatment in vivo of sheep with an original preparation obtained from the Phaseolus vulgaris pods restores the erythrocyte lysates reactivity toward the two redox dyes and reduces the chromosomal abnormalities frequency induced by the mycoplasmal antigen. It was also demonstrated by optical and electronical microscopy that the Smise line mouse meiocytes exhibit chromosomal abnormalities induced by the cyclophosphamide treatment in vivo. In the case of concomitant treatment with the cyclophosphamide and C vitamin the same frequency of abnormalities was recorded as in the simple treatment with the drug.

Adjuvants, Immunologic↗