Volume 9 (2004)

QUANTITATIVE DEPENDENCES BETWEEN THE WATER ORGANIC CHARGE AND THE MINERALISATION MICROBIAL POPULATIONS

CARMEN NICOLESCU

The natural fish ponds are lake ecosystems in which there is a large amount of organic mater from the natural recycling of the organisms living here and most from the not consumed fodder. The organic dead matter is in various stages of decomposition. The source of the water resident organic matter may be autochthonous, but most of it is allochthonous from many kinds of human activity. Feeding can be considered the major input of organic matter in the fish ponds (Atlas 1997). The large amount of organic matter induces the development of the specific autochthonous microbiota. Its principal ecological function is the mineralisation of the organic biodegradable substances. The water quality of the fish ponds depends on the mineralisation activity of the autochthonous microbiota and also of the fresh water flow brought by the water alimentation (Pepper and all. 1995). The organic matter decomposition is the most important mineralisation step. It is carried out by many groups of microorganisms which follow several subsequent degradation steps up to lower and lower molecular weight compounds. After the decomposition of plant material like cellulose there can result CH4 and other gases like CO2 and H2. After the decomposition of proteins, which are the principal ingredient of the artificial fodder, there can result aminoacids, NH3, H2S. The mineralization-linked microbiota is represented by anaerobes, facultative anaerobes and aerobes. The ability to decomposition organic matter is strictly specific to heterotrophic organisms (Nicolescu 2002). The intensity of the mineralization process depends on the quantitative and qualitative autochthonous microbiota implicated in the recycling of the organic matter. Some abiotic parameters of the biotope are modeling this process (Zarnea 1994, Pepper and all. 1995). The aim of this study is to perform a quantitative and qualitative analyse of the some mineralisation microorganisms in three natural fish ponds and their quantitative and qualitative dependence on the water organic load.

BIOCHEMICAL MARKERS DYNAMICS IN FISSION YEAST SCHIZOSACCHAROMYCES POMBE

MIRELA MIHAELA CÎMPEANU, CRISTIAN SORIN CÎMPEANU

One of the very important steps in a professional characterization of mutants must be the monitoring of DNA content, which can offer valuable information on mutagenesis effects on nucleic acids level (Cîmpeanu et al., 1996). Proteins phosphorylation by kinases and phosphatase represent a very important post-transductional mechanism, in eukaryotic cells, in biological processes control (metabolic pathway, signals transmission, gene expression and cell cycle differentiation) (Yanagida et al., 1992). On S. pombe, acid phosphatase, another subject of our investigation, represents a key enzyme involved in cell surface modulation and cellular differentiation during cell cycle, especially in sexual process initiation (Schwaninger et al., 1990). Schweingruber and Schweingruber (1982) show that enzyme activity and its level is repressed on rich media (with abundant phosphate source) and derepressed on minimal media, or media used for induction of sexual cycle. It’s obvious that the investigations on acid phosphatase level may offer important information on sexual cell cycle on normal and mutant strains previously induced P1 – P12 (Pricop et al., 1996).

VARIATIONS IN SOLUBLE PROTEINS CONTENT OF TWO YEAST SPECIES, DURING THE CELL CYCLE

CRISTIAN SORIN CIMPEANU, MIRELA MIHAELA CIMPEANU

Glucose is also the main carbon source used by the cells of Sacch. cerevisiae for growing and reproduction, both in laboratory and industrial cultivation conditions. Sacch. cerevisiae could also use other monosaccharide (D-fructose, D-galactose, D-mannose, D-ribose), as well as disaccharides (saccharose, maltose and even lactose), in the same purpose (Anghel et al., 1989). The fission yeast S. pombe and the budding yeast Sacch. cerevisiae uses, as nitrogen sources (similar to other yeasts), the inorganic nitrogen combinations, or the organic nitrogen. The transport mechanisms of sugars and amino acids into S. pombe and Sacch. cerevisiae cells are now well known: these molecules could be absorbed from the culture medium even by passive diffusion or by active transport against the concentration gradient, using the specific carrier-proteins, located in plasmalema (Coen et al., 1994). Sacch. cerevisiae is able to convert sugars, in order to provide its vital energy and carbon backbones, even by fermentation (or anaerobic glycolysis, via the Embden – Meyerhof – Parnas pathway), even by aerobic cathabolisation (via the Krebs cycle and cytochromes chain) (Brul et al, 1997). Less is known about the relations between the sugars and protein metabolisation during the cell cycle of S. pombe and Sacch. cerevisiae and this is the main topic of the present paper.