Slow heat rate increases yeast thermotolerance by maintaining plasma membrane integrity.

Thermal resistance of Saccharomyces cerevisiae was found to be drastically dependent on the kinetics of heat perturbation. Yeasts were found to be more resistant to a plateau of 1 h at 50 degrees C after a slope of temperature increase (slow and linear temperature increments) than after a shock (sudden temperature change). Thermotolerance was mainly acquired between 40-50 degrees C during a heat slope, i.e., above the maximal temperature of growth. The death of the yeasts subjected to a heat shock might be related to the loss of membrane integrity: intracellular contents extrusion, i.e., membrane permeabilization, was found to precede cell death. However, the permeabilization did not precede cell death during a heat slope and, therefore, membrane permeabilization was a consequence rather than a cause of cell death. During a slow temperature increase, yeasts which remain viable may have time to adapt their plasma membrane and thus maintain membrane integrity.     

A note on a modified membrane-Bovis agar for the enumeration of Streptococcus bovis by membrane filtration

The effect of dilution and temperature on the antibacterial properties of potassium sorbate was determined. The time taken to kill a standard inoculum of Escherichia coli was increased considerably after either dilution of the preservative or lowering of the temperature. The value for the concentration exponent, eta, was approximately 3 and that for the temperature coefficient, Q10, was 2.3.     

Salinity and germination of annual Melilotus from the Guadalquivir delta (SW Spain)

The germination response to NaCl treatments has been studied in Melilotus seed populations collected from saline and non-saline soils in the Guadalquivir delta. The rank orders for salt tolerance and seed weight were the same in the threeMelilotus species living in this area:Melilotus messanensis>M. segetalis>M. indica. Within the species, differences in germination response to salinity were found inM. indica (6 populations) andM. segetalis (8 populations). The relationship between salt tolerance during germination and salinity of maternal habitat is discussed.     

The role of carrier ATPases and neuromediators in neurological disorders

Physiological and biochemical processes which take place in the nervous system at stroke and neurotrauma are reviewed, and the experience of using low doses of steroid derivatives with piridamole in the treatment of central nervous system (CNS) disorders is summarized. ATPases (including Na,K-ATPase) are reported to play an important role in CNS functioning, the correlation between Na,K-ATPase activity and the extent of CNS injury is revealed. The use of NMR-spectroscopy method for investigation of brain and spinal cord condition in vivo is suggested.     

Tyrosine mutations within the alpha platelet-derived growth factor receptor kinase insert domain abrogate receptor-associated phosphatidylinositol-3 kinase activity without affecting mitogenic or chemotactic signal transduction.

A phosphatidylinositol-3 (PI-3) kinase activity of unknown biological function associates with tyrosine kinase-containing proteins, including a number of growth factor receptors after ligand stimulation. In the beta platelet-derived growth factor (beta PDGF) receptor, phosphorylation of a specific tyrosine residue within the kinase insert domain was required for its interaction with this enzyme. We show that substitutions of phenylalanine for tyrosine residue 731 or 742 within the kinase insert domain of the alpha PDGF receptor do not impair PDGF-induced tyrosine phosphorylation of the receptor or of an in vivo substrate, phospholipase C-gamma. Moreover, phosphatidylinositol turnover in response to ligand stimulation is unaffected. However, both lesions markedly impair receptor association with PI-3 kinase. Antiphosphotyrosine antibody-recoverable PI-3 kinase was also dramatically reduced in PDGF-stimulated cells expressing either mutant receptor. Since neither mutation abolished PDGF-induced mitogenesis or chemotaxis, we conclude that alpha PDGF receptor-associated PI-3 kinase activity is not required for either of these major PDGF signalling functions.     

Conclusive diagnosis of hepatic and pancreatic malignancies by fine needle aspiration

A study of the diagnosis of hepatic and pancreatic malignancies by fine needle aspiration (FNA) was made, based on 221 aspirates obtained from 209 patients with histologic or clinical confirmation: 159 with hepatic and 50 with pancreatic lesions. The values of sensitivity, specificity and predictivity for positive FNA results were, respectively, 0.84, 0.96 and 1.0 for the liver and 0.76, 1.0 and 1.0 for the pancreas. The composition of the case material showed an incidence of malignant tumors of the liver and pancreas of 84% and 60%, respectively (among which the primary malignancies were 39% and 48%), while nonneoplastic lesions had incidences of 14% and 40%. However, conclusive FNA diagnoses of the histologic type of the primary and the site of origin of metastatic tumors were made in 60% of the hepatic lesions but in only 9% of the pancreatic lesions. Primary hepatocellular carcinoma was diagnosed by FNA of the liver in 95% of the cases; FNA specifically diagnosed 42% of intrahepatic bile duct carcinomas and 40% of hepatic metastases. These findings correlate with the unique cytologic features of primary hepatocellular carcinoma of intrahepatic rather nonspecific morphology of carcinoma of intrahepatic and extrahepatic origin, as well as of pancreatic ductal origin.     

Enzyme-linked immunosorbent assay (ELISA) for the identification of mosquito bloodmeals

An ELISA for the identification of mosquito bloodmeals (MBM) is described. The technique makes use of commercial antisera and allows to investigate at least three different animal sources on the same MBM. The efficiency of identification is 100% for up to 20 hrs-digested MBM.