Single-step,rapid separation of acidic and basic isoenzymes from commercial horseradish peroxidase

A simple and sensitive high-performance liquid chromatography method with electrochemical detector is described for the determination of free 3-methoxy-4-hydroxyphenylacetic acid (HVA) in human plasma. The method does not involve any extraction, is specific and reproducible, and has the potential to measure serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) simultaneously. The plasma concentration of free HVA in eight normal, healthy adult volunteers was 10.9 ± 4.6 (mean ± SD). In a preliminary study, in one schizophrenic patient the plasma HVA increased twofold after neuroleptic treatment.     

Dormancy in peach (Prunus persica L.) flower buds

Morphological studies were carried out with peach flower buds collected monthly in 1989 and 1990, from two months before leaf fall (7 March) until two to three weeks before bloom (7/8 August). Chilled (2–4°C for 30 days) and unchilled buds were exposed to 20 to 25°C, 100% RH and continuous light. Gibberellin A₃ (3 ng or 30 ng) was applied to some of the non-chilled cuttings at three days intervals. Then, 12, 19, and 26 days after they were planted, the buds were sampled and processed for histological studies. Cultured flower buds (chilled or unchilled) had accelerated anther and gynoecium morphogenesis after 12 days under controlled conditions, compared to buds processed immediately after collection from the field. Chilling treatment augmented the bud culture effect, while Gibberellin A₃ applications to the excised buds retarded bud morphogenesis to a stage comparable to that of buds collected directly from the field. This, suggests that the comparatively high levels of Gibberellin A_1/3 we previously found in mid winter [15, 18] could be at least one of the factors that controls floral bud dormancy by retarding anther and gynoecium development.     

Membrane protein synthesis in Micrococcus lysodeikticus and selective effect of chloramphenicol.

Micrococcus lysodeikticus cytoplasmic membranes labeled with ]-14C]arginine plus [-14C]-threonine were prepared and subjected to mild washing treatments to fractionate membrane proteins. Polyacrylamide gel electrophoresis of total membranes, in the presence of sodium dodecyl sulfate, results in the separation of 28-30 bands of labeled protein. Three peaks of protein show higher specific radioactivity than the others. Chloramphenicol at 100 mug/ml inhibits the incorporation of labeled precursors into membrane proteins by 45-70 percent, some of them being more affected by the antibiotic. From all available results, we suggest that the partial inhibitory effect shown by this antibiotic could be due to the existence of specific biosynthetic sites for some membrane proteins, which are differently affected by chloramphenicol.     

Post-thawing survival of motile ram sperm after isolation by layering on protein columns

Post-thawing survival of ram sperm was examined after semen which had been layered on top of isolation columns containing solutions of bovine serum albumin (BSA) in Tris diluent was processed for freezing by the pellet method. Sperm isolated from the bottom of the BSA column had better post-thawing survival than sperm from the top of the column. The efficiency of sperm isolation was affected by the concentration of BSA in the column, the holding time of semen on the column and the concentration of sperm in the layered semen. The best post-thawing survival of sperm occurred when semen diluted to a concentration of 200 x 10(6) sperm/ml was layered on a column of 6% BSA in Tris diluent and the bottom layer of the column was isolated for freezing after two hours' holding time.     

Effect of monensin on osmotic water flow across the toad bladder and its stimulation by vasopressin and cyclic AMP

Summary The effects of the sodium ionophore monensin on osmotic water flow across the urinary bladder of the toadBufo marinus were studied. Monensin alone did not alter osmotic water flow; however, the ionophore inhibited the hydrosmotic response to vasopressin and cyclic AMP in a dose-dependent manner. The inhibitory effects of monensin were apparent when the ionophore was added to the serosal bathing solution but not when it was added to the mucosal bathing solution. The inhibitory effect of serosal monensin required the presence of sodium in the serosal bathing solution but not the presence of calcium in the bathing solutions. Thus, it appears that intracellular sodium concentration is a regulator of the magnitude of the hydrosmotic response to vasopressin and cyclic AMP.     

Effect of ACE inhibition on the fetal kidney: decreased renal blood flow.

The kidneys of nine fetuses whose mothers were chronically hypertensive were examined microscopically. Three of these mothers used antihypertensive agents throughout pregnancy including one who used an angiotensin-converting enzyme (ACE) inhibitor. The tubular defects found in these kidneys were compared to the kidneys of 20 normal controls, 13 fetuses with various multiple malformation syndromes and six cases of the twin to twin transfusion syndrome. Evidence from these cases as well as the literature suggest that the primary mechanism by which ACE inhibitors affect development of the fetal kidney is through decreased renal blood flow.     

Role of the bacterial and phage recombination systems and of DNA replication in genetic recombination of UV-irradiated phage lambda

Summary In this paper are studied in E. coli K12 the influence of the bacterial Rec and phage Red recombination systems on the rescue of the O ⁺ gene from the prophage by a superinfecting O ^- phage, UV irradiated or not. In the absence of UV irradiation the Red system produces more recombinants that does the Rec system, and its action requires DNA replication. The presence of UV lesions in the DNA facilitates the action of the Rec system, which is more efficient in this instance than the Red system and can act in the absence of DNA replication. In all cases, there is a cooperation between the two generalized recombination systems.