Changes in the urea concentration during controlled wine aging by two “flor” veil-forming yeasts

Summary Contents of arginine, ornithine, urea and ammonia in wine were monitored during aging process by two flor veil-forming yeast strains. The patterns of yeast growth were different for the two strains studied. Urea excretion and uptake were dependent on yeast strain, so that finished wines showed different concentrations of urea. The effect of limited aeration was also investigated for Saccharomyces cerevisiae var. capensis. The results indicated that aeration promoted yeast growth in veil, thus reducing urea concentration until its exhaustion in wine.     

Casein kinase 2 inactivation by Mg2+, Mn2+ and Co2+ ions

In order to elucidate the relationship between hypertension and hypertrophy in the production of heat shock proteins, we studied the induction of the HSP72 synthesis by the heart and gracilis muscles of normo (WKY) and hypertensive (SHR) rats subjected to hyperthermia (42°C±0.5 for 15 min). Two age groups were investigated in each strain: young (2 months, with developing cardiac hypertrophy) and old (18 months, with fully developed chronic cardiac hypertrophy). The gracilis muscle never developed hypertrophy, independently of hypertension or aging. 72 kDa inducible protein was determined by Western blot analysis using a specific monoclonal antibody. We also used a commercial standard, loaded on each blot, to quantitate densitometrically the signal.The heart of young SHR responds to heat shock more than their normotensive age-matched control (298.8±24.7% vs 88.3 ±8.5%, p<0.001). This response is not maintained during aging as we did not find any significant difference between normo-and hypertensive old rats after exposure to hyperthermia (43.6±5.3% vs 65.3±10.4%).Unlike the heart, the gracilis muscle shows a basal spontaneous HSP72 synthesis in both the SHR (71.4±10.8%) and WKY (40.6±11.7%) animals. There was a significant increase in HSP72 synthesis in the gracilis muscle of young SHR with respect to their control (186.2±18.7% vs 115.8±9.9%, p<0.02) which was maintained also during aging (171.9±17.3% vs 95.2±10.5%, p<0.01).In conclusion, these data show that hypertension results in an increased synthesis of HSP72 both in cardiac and gracilis muscle in response to heat shock. This abnormal response is attenuated by aging in the heart but not in the gracilis muscle. Thus, the abnormality seems to be independent from hypertrophy and linked to genetic determination of the disease.     

Recent advances on cyclins, CDKs and CDK inhibitors

In eukaryotes, cell division is controlled by cyclin-dependent kinases (CDKs). Here we summarize a few new developments on the regulation of the cell cycle by CDK-cyclin complexes. We have focused on three aspects in which there has been recent progress: the structural analysis of these complexes, the phenotypes of mice carrying knockouts of CDK inhibitors and the role of proteolysis in the regulation of the cell cycle.     

The larval development of lateral musculature in gilthead sea bream Sparus aurata and sea bass Dicentrarchus labrax

Fibre-type differentiation of the lateral musculature has been studied in Sparus aurata (L.) and Dicentrarchus labrax (L.) during larval development. Histochemical and ultrastructural techniques show two presumptive muscle layers and two germinative zones of presumptive myoblasts. At hatching, myotomal muscle consists of a monolayer of thin undifferentiated cells near the skin (first germinative zone) overlying another mono-layer of small diameter fibres extending hypaxially and epaxially away from the transverse septum. Below this, there is a much thicker, deep layer of fibres, generally large in diameter and polygonal in shape. The presumptive myoblasts are located between these two layers of fibres in the second germinative zone. Initially, the superficial and deep muscle fibres show high and low myosin ATPase activity, respectively. Both layers grow by generating new fibres from the two mentioned germinative zones. At the end of larval life, the superficial layer changes its histochemical profile from high to low myosin ATPase activity and, at the same time, intermediate or pink muscle fibres can be observed by oxidative activity (the NADH-TR reaction). Morphometric analysis shows a significant increase in mean fibre diameter during successive ages, as shown by the Student's t-test (hypertrophic growth). Skewness and kurtosis values of fibre diameters point to the generation of a new fibre population from the germinative zones (hyperplastic growth).     

Dinucleotide repeat polymorphism at the D4S2458 locus close to the PKD2 locus on human chromosome 4q

A new polymorphic CA repeat sequence was identified within the candidate region fot the autosomal dominant polycystic kidney disease type 2 (PKD2) locus. It should be a useful marker in the localization of this gene.     

Nitrogen-fixing cyanobacteria as source of phycobiliprotein pigments. Composition and growth performance of ten filamentous heterocystous strains

Ten strains of filamentous, heterocystous nitrogen-fixing blue-green algae (cyanobacteria) were screened for growth performance and tolerance to temperature, pH, irradiance and salinity, together with their potential as producers of phycobiliprotein pigments. Phycobiliproteins typically accounted for about 50% total cell protein, the prevalent type being C-phycocyanin, followed by alloppycocyanin, with levels of 17 and 11% d.wt, respectively, in some strains of Anabaena and Nostoc. C-phycoerythrin was the major pigment in several Nostoc strains, reaching 10% d.wt. Some strains represent, therefore, excellent sources of one or more phycobiliproteins. All strains tolerated an irradiance of ca 2000 μmol photon m^-2 s^-1. Anabaena sp. ATCC 33047 and Nostoc sp. (Albufera) exhibited the widest optimum range of both temperature (30–45 and 25–40 °C) and pH (6.5–9.5 and 6.0–9.0) for growth, the former also showing significant salt tolerance. In an outdoor open system, productivity of cultures of two phycoerythrin-rich strains of Nostoc was over 20 g (d.wt) m^-2 d^-1 during summer. The growth performance of the allophycocyanin-rich Anabaena sp. ATCC 33047 in outdoor semi-continuous culture has been assessed throughout the year. Productivity values under optimized conditions ranged from 9 (winter) to 24 (summer) g (d.wt) m^-2 d^-1.     

Saturation of penicillin-binding protein 1 by β-lactam antibiotics in growing cells of Bacillus licheniformis

With the help of a new highly sensitive method allowing the quantification of free penicillin-binding proteins (PBPs) and of an integrated mathematical model, the progressive saturation of PBP1 by various β-lactam antibiotics in growing cells of Bacillus licheniformis was studied. Although the results confirmed PBP1 as a major lethal target for these compounds, they also underlined several weaknesses in our present understanding of this phenomenon. In growing cells, but not in resting cells, the penicillin target(s) appeared to be somewhat protected from the action of the inactivators. In vitro experiments indicated that amino acids, peptides and depsipeptides mimicking the peptide moiety of the nascent peptidoglycan significantly interfered with the acylation of PBP1 by the antibiotics. In addition, the level of PBP1 saturation at antibiotic concentrations corresponding to the minimum inhibitory concentrations was not constant, suggesting that additional, presently undiscovered, factors might be necessary to account for the experimental observations.     

L-Arabinose is not a gratuitous inducer of α-galactosidase from Saccharomyces carlsbergensis

L-Arabinose has been described as a gratuitous inducer of the yeast -galactosidase. This has been found to be an artefact resulting from galactose contamination of commercial samples of L-arabinose. The inactivation produced on UDP-glucose 4-epimerase by the pentose does not amplify the inducer activity of contaminating D-galactose.