Utilization of phosphate diester by the marine diatom Chaetoceros ceratosporus

Utilization of phosphate diester (PDE) and phosphodiesterase(PDEase) production by five marine phytoplankton species wereexamined in the laboratory to evaluate the contribution of PDEto the growth of phytoplankton. Among the five marine phytoplanktonspecies tested, only Chaetoceros ceratosporus was able to usethe PDE compound, bis(p-nitrophenyl) phosphate (bis-NPP), effectivelyas a sole phosphorus source. In addition, C. ceratosporus simultaneouslyproduced both PDEase and alkaline phosphatase (APase) at almostequal activity levels under the phosphate-deficient condition.These results suggest that PDE compounds presumably play animportant role as a phosphorus source for PDEase-producing phytoplanktonin coastal environments.     

A newly established human acute lymphoblastic leukemia cell line with characteristics of the earliest B-cell maturation

A new human acute lymphoblastic leukemia (ALL) cell line, designated HBL-3, was established from the bone marrow of a patient with non-T-ALL. The HBL-3 cell line expressed B4 (CD 19), BA-1 (CD 24) and HLA-DR antigens, but not surface immunoglobulin (SIg) or cytoplasmic immunoglobulin (CIg). The cell line lacked the common acute lymphoblastic leukemia antigen (CALLA) and antigenic markers characteristic of T-cell and myeloid cell lineages. The HBL-3 cells had structural rearrangements of both the homologous chromosome 9s, including a translocation with chromosome 1 which has been reported in a patient with common ALL. The cell line had rearranged immunoglobulin heavy chain genes but retained germ-line κ light chain genes and germ-line T-cell receptorβ- and γ-chain genes. The HBL-3 cell line was strongly positive for terminal deoxynucleotidyl transferase (TdT). These findings indicate that the HBL-3 cell line is derived from the earliest B-cell committed to B-cell lineage.     

Sigma receptors in schizophrenic cerebral cortices

Antipsychotics represent high affinity for sigma receptors and sigma-like drugs often have the psychotomimetic properties. Besides, the receptors are unevenly distributed in human brain. These findings suggest that sigma receptors might be involved in the pathophysiology of schizophrenia. Sigma receptors in rat and human brain were measured with [³H]-1, 3, di-o-tolylguanidine (DTG) and non-specific binding of [³H]DTG was determined in the presence of 10^–5M haloperidol. Monovalent and divalent cations strongly inhibited [³H]DTG binding. Glutamate, aspartate and glycine also decreased the binding to human cerebral membranes. With post-mortem brain samples from 12 schizophrenics and 10 controls, sigma receptors were measured in 17 areas of cerebral cortex. Sigma receptors binding showed the regional differences in the cortex, but no significant differences between schizophrenics and controls were observed except the superior parietal cortex where the binding significantly increased in the schizophrenic group. These results suggest that sigma receptors in cerebral cortices might not be directly concerned with the pathophysiological role in schizophrenia.Dedicated to Dr. Morris Aprison. Received too late for publication in special issue.     

Studies on Muscarinic Binding Sites in Human Brain Identified with [3H]Pirenzepine

Pirenzepine, a potent antimuscarinic agent with apparent selectivity for a subtype (M1) of muscarinic receptors, was used in tritiated form to characterize its binding to human brain tissue. Specific [3H]pirenzepine binding showed rapid association and dissociation. From kinetic and competitive binding experiments, its KD was 5.5 nM and 9 nM, respectively. Regional distribution of [3H]pirenzepine binding determined in parallel with [3H]quinuclidinyl benzilate binding, a nonselective muscarinic antagonist, indicated a significant correlation for the maximum number of binding sites for the two radioligands in 13 brain regions, with the highest amount of binding for each in the putamen and the least in the cerebellum. Binding for [3H]pirenzepine averaged 57% of that for [3H]quinuclidinyl benzilate, with a range of 20% (cerebellum) to 77% (frontal cortex). Most antidepressants and neuroleptics tested had affinities for [3H]pirenzepine binding sites that were not significantly different from their previously reported values obtained with the use of [3H]quinuclidinyl benzilate.     

Suppressors of temperature-sensitive mutations in a ribosomal protein gene, rpsL (S12), of Escherichia coli K12

Summary Temperature-sensitive (ts) mutations were isolated within a ribosomal protein gene (rpsL) of Escherichia coli K12. Mutations were mapped by complementation using various transducing phages and plasmids carrying the rpsL gene, having either a normal or a defective promoter for the rpsL operon. One of these mutations, ts118, resulted in a mutant S12 protein which behaved differently from the wild-type S12 on CM-cellulose column chromatography. Suppressors of these ts mutations were isolated and characterized; one was found to be a mutation of a nonribosomal protein gene which was closely linked to the RNAase III gene on the E. coli chromosome. This suppressor, which was recessive to its wild-type allele, was cloned into a transducing phage and mapped finely. A series of cold-sensitive mutations, affecting the assembly of ribosomes at 20°C, was isolated within the purL to nadB region of the E. coli chromosome and one group, named rbaA, mapped at the same locus as the suppressor mutation, showing close linkage to the RNAase III gene.     

Characterization of three forms of cytochrome P-450 inducible by 3-methylcholanthrene in Golden hamster livers with special reference to aflatoxin B1 activation

Three forms of cytochrome P-450 of liver microsomes of 3-methylcholanthrene-treated Golden hamsters were purified and characterized as regards their catalytic activity toward aflatoxin B1-related hepatocarcinogenic mycotoxins. These include two major forms, designated as cytochrome P-450-AFB (P-450-I) and P-450-II, and one minor form, P-450-III. Cytochromes P-450-AFB, P-450-II, and P-450-III have their absorption maximum in the carbon monoxide-complex of the reduced form at 448.5, 447.0, and 448.0 nm, have apparent molecular weights of 56,000, 58,000, and 59,500, and are in the low spin, high spin, and low spin state, respectively. Of these, cytochrome P-450-AFB was shown to be highly active in the mutagenic activation of aflatoxin B1-related hepatocarcinogens such as sterigmatocystin and O-methylsterigmatocystin. Activation of aflatoxin B1 by hepatic microsomes of 3-methylcholanthrene-treated hamsters was inhibited almost completely by the antibody against P-450-AFB but not by the antibody against P-450-II, indicating that P-450-AFB is the major component responsible for the activation of aflatoxin B1 by hamster liver. Western blot analysis demonstrated that no protein cross-reacted with the antibody to P-450-AFB in the liver microsomes from guinea pig, rat, mouse, and house musk shrew (Suncus murinus) treated with 3-methylcholanthrene, while one or two proteins cross-reacted with the antibody to P-450-II in the liver microsomes of these animals.     

A comparison of sweating responses during exercise and recovery in terms of sweating rate and body temperature

Based on the hypothesis that the relation between sweating rate and body temperature should be different during exercise and rest after exercise, we compared the sweating response during exercise and recovery at a similar body temperature. Healthy male subjects performed submaximal exercise (Experiment 1) and maximal exercise (Experiment 2) in a room at 27° C and 35% relative humidity. During exercise and recovery of 20 min after exercise, esophageal temperature (Tes), mean skin temperature, mean body temperature ( ), chest sweating rate ( ), and the frequency of sweat expulsion (F _SW) were measured. In both experiments, andF _SW were clearly higher during exercise than recovery at a similar body temperature (Tes, ). was similar during exercise and recovery, or a little less during the former, at a similarF _SW. It is concluded that the sweating rate during exercise is greater than that during recovery at the same body temperature, due to greater central sudomotor activity during exercise. The difference between the two values is thought to be related to non-thermal factors and the rate of change in mean skin temperature.