Growth and fermentation characteristics of new selected strains of Saccharomyces at high temperatures and high cell densities

Maintenance of high cell viability was the main characteristic of our new strains of thermotolerant Saccharomyces. Total sugar conversion to ethanol was observed for sugarcane juice fermentation at 38-40 degrees C in less than 10 h and without continuous aeration of the culture. Invertase activity differed among the selected strains and increased during fermentation but was not dependent on cell viability. Invertase activity of the cells and optimum temperature for growth, as well as velocity of ethanol formation, were dependent on medium composition and the type of strain used. At high sugarcane syrup concentrations, the best temperature for ethanol formation by strain 781 was 35 degrees C. Distinct differences among the velocities of ethanol production using selected strains were also observed in sugarcane syrup at 35-38 degrees C.     

Scanning electron microscopy of Setaria cervi adult male worms

Scanning electron microscopy studies of adult Setaria cervi male worms showed the presence of horn-like lateral appendages and characteristic striated bands on the ventral side of the tail. All other features were indistinguishable from other members of the genus Setaria.     

Occurrence of macro B chromosomes in Astyanax scabripinnis paranae (Pisces,Characiformes, Characidae)

B chromosomes occur in several Neotropical fish species. Cytogenetic analysis of 27 specimens (15 females and 12 males) of Astyanax scabripinnis paranae from the Araquá river (a small headwater tributary of the Tietê river) shows that this population has 2n=50 chromosomes (4M+30 SM+4ST+12A), two chromosome pairs with NORs and conspicuous C-band positive blocks in the terminal position of the long arm of four chromosome pairs. In this population, eight females presented 2n=51 chromosomes and the extra chromosome was a large metacentric similar in size and morphology to the first chromosome pair in the karotype. This accessory chromosome is entirely heterochromatic in C-banded metaphases and shows a late replication pattern evidenced by BrdU incorporation. There was no significant correlation between the presence of B chromosomes and increased NOR activity at the P>0.05 level. Some aspects related to these B chromosomes are discussed.     

Comparison of Rates of Local Cerebral Glucose Utilization Determined with Deoxy[l-14C]glucose and Deoxy[6-14C]glucose

The activity of the pentose phosphate shunt pathway in brain is thought to be linked to neurotransmitter metabolism, glutathione reduction, and synthetic pathways requiring NADPH. There is currently no method available to assess flux of glucose through the pentose phosphate pathway in localized regions of the brain of conscious animals in vivo. Because metabolites of deoxy[1-14C]glucose are lost from brain when the experimental period of the deoxy[14C]glucose method exceeds 45 min, the possibility was considered that the loss reflected activity of this shunt pathway and that this hexose might be used to assay regional pentose phosphate shunt pathway activity in brain. Decarboxylation of deoxy[1-14C]glucose by brain extracts was detected in vitro, and small quantities of 14C were recovered in the 6-phosphodeoxygluconate fraction when deoxy[14C]glucose metabolites were isolated from freeze-blown brains and separated by HPLC. Local rates of glucose utilization determined with deoxy[1-14C]glucose and deoxy[6-14C]glucose were, however, similar in 20 brain structures at 45, 60, 90, and 120 min after the pulse, indicating that the rate of loss of 14CO2 from deoxy[1-14C]glucose-6-phosphate in normal adult rat brain is too low to permit assay pentose phosphate shunt activity in vivo. Further metabolism of deoxy[1-14]glucose-6-phosphate via this pathway does not interfere during routine use of the deoxyglucose method or explain the progressive decrease in calculated metabolic rate when the experimental period exceeds 45 min.     

Vaccinia virus-specific human CD4+ cytotoxic T-lymphocyte clones.

Vaccinia virus-specific cytotoxic T-lymphocyte (CTL) clones were established from a healthy donor, who had been immunized with vaccinia virus vaccine, by stimulation of peripheral blood lymphocytes with UV-inactivated vaccinia virus antigen. The phenotype of all of the clones established was CD3+ CD4+ CD8- Leu11-. We used a panel of allogenic vaccinia virus-infected B-lymphoblastoid cell lines and demonstrated that some of the clones recognized vaccinia virus epitopes presented by human leukocyte antigen (HLA) class II molecules. Monoclonal antibodies specific for either HLA-DP or HLA-DR determinant reduced the cytotoxicity of specific clones. The HLA-restricted cytotoxicity of the clones is vaccinia virus specific, because vaccinia virus-infected but not influenza virus-infected autologous target cells were lysed. Using vaccinia virus deletion mutants, we found that some of the CTL clones recognize an epitope(s) that lies within the HindIII KF regions of the vaccinia virus genome. These results indicate that heterogeneous CD4+ CTL clones specific for vaccinia virus are induced in response to infection and may be important in recovery from and protection against poxvirus infections.     

Effect of hydrogen sulfide on growth of sulfate reducing bacteria

A culture of sulfate reducing bacteria (SRB) growing on lactate and sulfate was incubated at different pH values in the range of 5.8-7.0. The effect of pH on growth rate was determined in this pH range; the highest growth rate was observed at pH 6.7. Hydrogen sulfide produced from sulfate reduction was found to have a direct and reversible toxicity effect on the SRB. A hydrogen sulfide Concentration of 547 mg/L (16.1 mM) completely inhibited the culture growth. Comparison between acetic acid and hydrogen sulfide inhibition is presented and the concomitant inhibition kinetics are mathematically described. (c) 1992 John Wiley & Sons, Inc.     

Assessment of genetic diversity and population structure of Xanthomonas oryzae pv. oryzae with a repetitive DNA element.

A repetitive DNA element cloned from Xanthomonas oryzae pv. oryzae was used to assess the population structure and genetic diversity of 98 strains of X. oryzae pv. oryzae collected between 1972 and 1988 from the Philippine Islands. Genomic DNA from X. oryzae pv. oryzae was digested with EcoRI and analyzed for restriction fragment length polymorphisms (RFLPs) with repetitive DNA element as a probe. Twenty-seven RFLP types were identified; there was no overlap of RFLP types among the six races from the Philippines. Most variability (20 RFLP types) was found in strains of races 1, 2, and 3, which were isolated from tropical lowland areas. Four RFLP types (all race 5) were found among strains isolated from cultivars grown in the temperate highlands. The genetic diversity of the total population of X. oryzae pv. oryzae was 0.93, of which 42% was due to genetic differentiation between races. The genetic diversities of strains collected in 1972 to 1976, 1977 to 1981, and 1982 to 1986, were 0.89, 0.90, and 0.92, respectively, suggesting a consistently high level of variability in the pathogen population over the past 15 years. Cluster analysis based on RFLP banding patterns showed five groupings at 85% similarity. The majority of strains from a given race were contained within one cluster, except for race 3 strains, which were distributed in three of the five clusters.     

Immunocytochemical identification of neuroendocrine markers in human cardiac paraganglion — like structures

Summary Paraganglion-like structures (PLS) containing chromaffin-positive cells have been reported to be present in the adult human heart. The present work was initiated in order to evaluate the densitity of these structures in the interatrial septum and to study the presence of immunoreactivity of their cells to NSE and PGP 9,5 antibodies, two neuroendocrine markers. Six hundred 6-m paraffin serial sections were obtained from the upper third of the interatrial septum from six adult human hearts. From 2 to 12 paraganglia were found in each case, and their principal cells stained positively with NSE and PGP 9,5 antibodies. Depending on how these PLS related to other cardiac structures, four different types were identified: Type I — True paraganglia (located adjacent to ganglia or nerve fibers); Type II — Free paraganglia (immersed in the interatrial adipose tissue, without evident connection to other structures); Type III — Intraganglionic paraganglia (located within the nervous ganglia); Type IV — Intramyocardic paraganglia (small nests of immunoreactive cells closely related to myocardiocyte bundles). These cardiac paraganglia, which probably belong to the visceral-autonomic group, may have a role in the regulation of the cardiac function and in the adaptive mechanisms of the heart. Its is also possible that they originate functioning and non-functioning tumours.Work supported by grants from FINEP and CNPq (Brazil)     

Expression and polymorphism of a Trypanosoma cruzi gene encoding a cytoplasmic repetitive antigen.

The study of the expression of a Trypanosoma cruzi gene encoding a cytoplasmic repetitive antigen (CRA) during the metacyclogenesis process shows that this gene is not expressed in metacyclic trypomastigote forms of the parasite. However, a slight increase in CRA expression was observed following the nutritional stress of epimastigotes which precedes T. cruzi metacyclogenesis in vitro. The comparison of the expression of CRA in different T. cruzi strains shows that this gene is highly polymorphic: some strains display one and others display two polypeptides reacting with a CRA antiserum. The comparison of T. cruzi G-49 strain and Dm 28c clone shows that they display rather different Northern and Southern blot profiles when probed with a clone corresponding to the repetitive region of the CRA gene. A similar polymorphism was also observed for the gene encoding a flagellar repetitive antigen, suggesting that gene polymorphism might be a common feature of many T. cruzi genes.