Identification of two glutaminases inRhizobium etli

We present evidence thatRhizobium etli has two glutaminases differentiated by their thermostability and electrophoretic mobility. The thermostable glutaminase (B) is constitutive, in contrast with the thermolabile glutaminase (A), which is positively regulated by glutamine and negatively regulated by ammonium and by the carbon source. In distinction to glutaminase A, glutaminase B plays a minor role in the utilization of glutamine as a carbon source, but it may play a role in maintaining the balance of glutamine and glutamate. By complementation of theRhizobium etli LM16 mutant that lacks glutaminase A, we have cloned the gene that codes for this enzyme.     

Isolation of Propionibacterium acnes from central nervous system infections

Propionibacterium acnes is a common skin colonizer and its involvement in central nervous system (CNS) infections may be related with previous neurosurgical procedures. P. acnes was isolated in pure or mixed cultures from ten patients with CNS infections during a 5-year period. The clinical presentation, treatment and outcome were retrospectively reviewed. Nine out of 11 patients had CNS infections after a neurosurgical procedure. The clinical presentation was: brain abscess (five patients), subdural or epidural empyema (four patients) and shunt meningitis (one patient). Three patients had also secondary meningitis. All patients received antibiotic therapy and all abscesses and empyemas were drained. The patient with shunt meningitis cured without catheter removal. Only one patient with a brain abscess by P. acnes died, but several months thereafter and as a consequence of a Gram-negative superinfection. P. acnes is a pathogen for the CNS and infections must be surgically managed under adequate antibiotic treatment.     

Use of F1 progeny of HolsteinxZebu cross cattle as oocyte donors for in vitro embryo production and gene microinjection

This study was designed to determine the possibility of using F1 crossbreed cattle (Holstein x Zebu) as donors of oocytes for in vitro fertilization (IVF) and for pronuclear gene microinjection into in vitro-produced embryos. In the first part of the experiment oocytes from Bos taurus (Holstein), Bos indicus (Zebu) and F1 crossbred Bos taurus x Bos indicus (Holstein x Zebu) genotypes were inseminated with Bos taurus (Holstein) semen and were allocated for in vitro embryo production using conventional IVF procedures. No differences were observed on the in vitro maturation (IVM) rates between breeds (Holstein x Holstein:85%, Zebu x Holstein:84% and Zebu x Holstein x Holstein:88%). Holstein cows yielded the highest number of cumulus oocyte complexes (6.8 per ovary) for in vitro maturation, differing (P<0.05) from Zebu x Holstein and Zebu x Holstein x Holstein F1 by 5.1 and 5.8, respectively. However, the Holstein breed also yielded the lowest percentage of cleavage (45.1 vs 71.9% for Zebu x Holstein and 65.1% for Zebu x Holstein x Holstein). Of the 3 genotypes, the hybrid F1 breed was the most efficient source of oocytes for the production of embryos capable of reaching morulae and blastocyst stages (76 250 ; P< 0.001). In the second part of the study, 599 oocytes from the F1 breed were fertilized in vitro, 1 group of 150 oocytes was used for the determination of the optimal pronuclear visualization period. The highest number of oocytes with 2 pronuclei was observed between 24 to 28 h after IVF (27 to 42%). The remaining 399 oocytes were microinjected with a gene construct bearing the bacterial lacZ gene as the reporter for gene expression. Survival of embryos to microinjection was 73.8%, and 45.5% of them (50 110 ) cleaved in culture. Of the microinjected embryos, 1 out of 50 showed beta-galactosidase activity. These findings indicate that a tropical crossbreed of cattle (Zebu x Holstein x Holstein) can be used as a source of oocytes for IVF programs and gene microinjection studies.     

Phytochrome-mediated effects on extracellular peroxidase activity, lignin content and bending resistance in etiolated Vicia faba epicotyls

Etiolated Vicia faba seedlings were exposed to continuous red light to investigate whether changes in extracellular peroxidase activity were correlated in time and localization with changes in extension growth and/or lignin content in the subapical region of the epicotyl. Continuous red light: (a) increased extracellular peroxidase activity after a lag of ca 0.5 h, followed by a maximum peak after 2.5 h due to slightly acidic isoforms (pI = 6–6.5, according to isoelectrofocusing gels), a minimum after 4 h and a second maximum after 8 h due to acidic isoforms (pI=4–5), (b) increased lignin content and epicotyl resistance to bending after a lag of ca 4 h, i.e. simultaneously with changes in acidic extracellular peroxidase activity, and (c) reduced extension growth to a stable rate after a lag of ca 1 h, not coinciding with the kinetics of any of the extracellular peroxidase isoforms. These effects of continuous red light were at least partially mediated by phytochrome. Tissue printing and anatomical studies revealed red light effects on extracellular peroxidase activity and lignin content mainly in the outer cortical parenchyma. The results are consistent with the involvement of phyto-chrome-mediated effects on extracellular peroxidases (acidic isoforms) in the transduction chain leading to lignin responses to red light.     

Trinucleotide (CAG) repeat expansion in chromosomes of Spanish patients with Huntington's disease

Huntington's disease (HD) is a neurodegenerative and hereditary disease characterized by progressive movement disorders and mental and behavioral abnormalities. The HD gene is an expanding and unstable trinucleotide repeat (CAG repeat sequences). We studied 77 individuals from 38 families with HD in an attempt to obtain information for genetic counselling and differential diagnosis. Our results indicate that individuals with more than 40 repeats will be affected by the disease, whereas those with fewer than 30 will be healthy. There can be some overlap between 30 and 40 repeats, and one should be careful when interpreting these results.     

Prevalence of Colonization Factor Antigens (CFAs) and Adherence to HeLa Cells in Enterotoxigenic Escherichia coli Isolated from Feces of Children in São Paulo

Fifty-eight enterotoxigenic Escherichia coli (ETEC) strains, isolated from children with and without diarrhea in Sao Paulo, were examined for the presence of colonization factor antigens (CFAs) and their ability to adhere to HeLa cells. Antisera to CFA/I, the coli surface (CS) antigens CS1CS3, CS2CS3, and CS2 of CFA/II, CFA/III, and CS5CS6 and CS6 of CFA/IV were used. CFAs were identified in 43% of the ETEC strains: 40% of the strains with CFAs harbored CFA/I, 24% carried CFA/II (CS1CS3), 24% carried CFA/IV (CS6), and 12% carried CFA/IV (CS5CS6). CFAs occurred mainly among ETEC strains producing only heat-stable (ST-I) enterotoxin and in strains also producing heat-labile toxin (LT-I). No ETEC strains tested expressed CFA/III. A marked change in serotypes of ST-I-producing strains was found in Sao Paulo between 1979 and 1990. Adherence to HeLa cells was detected in 14% of the ETEC strains. All of them had a diffuse adherence pattern and produced only ST-I, and 88% carried CS6 antigen.