Single-channel activity in sea urchin sperm revealed by the patch-clamp technique

Ionic fluxes are deeply involved in the response of spermatozoa to the egg. Using the patch-clamp technique, we show for the first time single ion channel activity in sea urchin spermatozoa and spermatozoa heads. Due to their small size gigaseals were obtained in suspended cells by applying suction through the pipette. The rate of gigaseal formation was very low and improved to 6% (n = 1145) when flagella were detached from sperm. Current-voltage curves created from single-channel events showed conductances of approx. 65 and 170 pS, suggesting the presence of two types of channels. At least one appears to be a K⁺ channel.     

Peroxidase activity in human red cell: a biological model for excited state molecules generation.

The presence of enzymically generated triplet acetone in red cells and energy transfer to eosin, rose bengal and 9,10-dibromoanthracene-2-sulfonate was indicate by: (1) product distribution; (2) K_ET τ_o, similar to the 2-methylpropanal/peroxidase/O₂ system; (3) correlation between hemolysis, oxygen uptake and photon emission; (4) membrane protection by energy acceptors, and (5) by comparison of the 2-methylpropanal/peroxidase/O₂ system with 2-methylpropanal/red cells/membranes/O₂ and 2-methylpropanal/acid extractable protein from red cells membrane/O₂ systems, which have a high peroxidase activity.This is the first report of a biological system producing a photohemolysis effect in the dark.     

Independent genes coding for three acidic proteins of the large ribosomal subunit from Saccharomyces cerevisiae

The yeast ribosome contains three acidic proteins, L44, L44', and L45, closely related from a structural point of view, that seem to play a functional role similar to that of proteins L7 and L12 in the bacterial ribosome. By screening a cDNA bank in lambda gt11 with specific polyclonal and monoclonal antibodies, recombinant phages expressing each one of the acidic proteins have been cloned. A unique copy of each gene is detected using the phage cDNA inserts as probes in nitrocellulose blots of yeast DNA digested with different restriction enzymes. The inserts were subcloned in the plasmid pUC19, and their physical maps and nucleotide sequences were determined. By using the cDNA inserts as probes in genomic DNA banks, DNA fragments carrying the acidic protein genes have been cloned, characterized, and sequenced. The results conclusively show that the three yeast acidic proteins are coded by independent genes and are not the result of a post-translational modification of the product of a unique gene, as in bacteria. Like most ribosomal protein genes, the gene for protein L44' has an intron and two upstream stimulatory boxes (UASrpg) fitting closely to the consensus sequence. The genes coding for proteins L44 and L45 lack introns and seem also exceptional in other characteristics of their sequences. Proteins L44 and L45 have amino acid sequences with about 80% similarity. Protein L44' is only 63% similar to the other two polypeptides. The three proteins have highly conserved carboxyl termini comprising the last 30 amino acids, and the first 10 amino acids of L44 and L45 are identical. The results cast doubts about the possibility of a similar role for the different acidic ribosomal proteins.     

Long-term effects of postovulatory aging of mouse oocytes on offspring: a two-generational study.

Aims of this study were to analyze the long-term effects of postovulatory aging of mouse oocytes on 1) reproductive traits of parental (F(0)) and first (F(1))-generation females (pregnancy rate, gestation length, litter size, perinatal death, and sex ratio of offspring) and 2) developmental and behavioral variables of F(1) and second-generation (F(2)) offspring (birth weight and weight gain during preweaning development, postnatal day of attainment of immediate righting, spontaneous motor activity, and passive and active conditioned learning ability). Hybrid (C57BL/6JIco x CBA/JIco) females were artificially inseminated at 13 h (control group) or 22 h (oocyte-aged group) after GnRH injection. Experimental (oocyte-aged group) F(0) females exhibited lower pregnancy rate, shortened gestation length, decreased litter size, higher perinatal death of their pups, and increased percentage of male offspring compared to control F(0) females. Postovulatory aging of oocytes was also associated with increased number of growth-retarded pups, delayed development of the righting reflex, and higher spontaneous motor activity and emotionality of F(1) offspring. Postovulatory aging of F(0) oocytes did not affect birth weight, weight gain during preweaning development, passive and active conditioned learning ability of F(1) offspring, or reproductive traits of F(1) females or developmental and behavior variables of F(2) offspring.     

Growth ofEscherichia coli B in a continuous culture under limitation by inorganic phosphate

During batch cultivation ofEscherichia coli in a medium deficient in inorganic phosphate, the growth curve after exhaustion of phosphate is linear. Results obtained in batch cultivation were used for deriving expressions for bacterial growth at a constant rate in a single-and multi-stage continuous system. It was found experimentally that the theoretical relations derived are satisfactory.     

T-cell dysfunction and hyperimmunoglobulinemia E in paracoccidioidomycosis

Various aspects of T and B cell mediated immunity were investigated in 20 well documented cases of active (10) or inactive (10) paracoccidioidomycosis (Pcm), as well as in 8 healthy individuals living in the endemic area of the disease. The results confirm previous reports that active Pcm produces diverse grades of depression of T cell mediated immunity. Such T cell dysfunction is not associated with a reduction in the number of peripheral E rosette-forming cells, and the immunodepression is reversed by chemotherapy. Sera from Pcm (active or inactive) patients have significantly increased levels of total IgE, but the actual proportion of IgE antibodies against P. brasiliensis was very low (0.4–0.6%). The highest levels of total IgE were found in active patients with disease-related immune depression, suggesting that T cell dysfunction might contribute to the excessive IgE production.