On the electromotor neurons of both electric organs of Pollimyrus isidori (Mormyridae, Teleostei)

The electromotor neurons (EMNs) of the adult electric organ of Pollimyrus isidori and the "giant neurons" (GNs) found in the more rostral part of the spinal cord were investigated both with light and electron microscopical methods. The two kinds of neuron are more or less similar in size, about 30 microns, and are found in the more dorsal part of the spinal cord. The EMNs show somatosomatic gap junctions, as do the GNs. In addition, chemical synapses could be found between nerve fibres and both types of neurons. Histochemical investigations show that the EMNs and the GNs are both AChE positive. On the basis of the arguments presented in the discussion, we believe that the "giant neurons" are the electromotor neurons of the larval electric organ of Pollimyrus isidori.     

Production of an extracellular maltase by thermophilic Bacillus sp. KP 1035.

Production of extracellular maltase was studied with thermophilic Bacillus sp. KP 1035, which was selected as the organism producing the highest levels of maltase. The final enzyme yield was increased by maltose, peptone, and yeast extract but reduced by succinate and fumarate. Maximum enzyme production was achieved at 55 degrees C and at an initial pH of 6.2 to 7.0 on a medium containing 0.3% maltose, 1% peptone, 0.1% meat extract, 0.3% yeast extract, 0.3% KH2PO4, and 0.1% KH2PO4. Maltase was synthesized in cytoplasm and accumulated as a large pool during the logarithmic growth phase, which preceded sporulation. At the end of this phase, the enzyme appeared in the culture broth, and its accumulation increased in parallel with a rise in the extracellular protein level. Maltase was stable for 24 h at 60 degrees C over a pH range of 5.6 to 9.0 and retained 95% of the original activity after treatment for 20 min at 70 degrees C at pH 6.8.     

Fluorimetric assay of sialic acids.

A fluorimetric assay has been developed for sialic acids in which sialic acids react with pyridoxamine to give fluorescent compounds in the presence of zinc ion and pyridine. This assay method is specific for unbound sialic acids and is a simple and sensitive procedure compared with the thiobarbituric acid assay of sialic acids.     

HLA antigens in Japanese populations.

HLA antigens in 841 healthy, unrelated Japanese from nine widely separated geographic localities were studied. The five most common antigens observed in order of decreasing frequency were for the HLA-A locus: HLA-A9, A2, A10, AW32 and A11; and for the HLA-B locus: HLA-'B5' (= HLA-B5+B17), BW40, B12, B14 and B8. The allelic frequency of undetected antigens of the HLA-A locus was .14-.37, and that of the HLA-B locus, .32-.67, indicating that there were serological difficulties in typing for Japanese antigens using antisera from Caucasians. Marked gene frequency clines were observed for HLA-A9 and HLA-A2 from south (Okinawa) to north (Nagoya). Two haplotypes, HLA-A9, B5 and HLA-A10, BW40 were shown to be in linkage disequilibrium in four of the nine subpopulations.     

OCCURRENCE AND FORMATION OF γ-GLUTAMYLPUTRESCINE IN MAMMALIAN BRAIN

—An unknown radioactive compound was detected in the basic fraction of the trichloroacetic acid extract of rat brain injected with radioactive putrescine. This compound was purified from bovine brain and identified as γ-glutamylputrescine by comparison of its behaviour with that of the synthesized glutamylamides. The amide seemed to be metabolized as rapidly as putrescine in rat brain.     

l-2-Amino-4-methylpimelic acid: A new amino acid from Lactarius species

A PC survey revealed the occurrence of an unusual amino acid in fruit bodies of the mushroom Lactarius quietus Fr. and a related species. This was identified as l-2-amino-4-methylpimelic acid, which has not been previously reported as a naturally occurring compound.     

Purified tyrosine kinases, the EGF receptor kinase and the src kinase, can catalyze the phosphorylation of the band 3 protein from human erythrocytes

The band 3 glycoprotein from human erythrocytes was found to be phosphorylated on tyrosine residues by the purified EGF receptor kinase and the purified src kinase in vitro. Kinetic analysis revealed that Km of the band 3 protein phosphorylation by the EGF receptor kinase was 0.17 microM and 0.65 microM in the absence and presence of EGF (3 X 10(-7)M), respectively, and that in the case of the src kinase it was 0.4 microM. From these data the band 3 protein can be regarded as one of the best substrates common for the EGF receptor kinase and the src kinase in vitro.     

Colchicine activates cell cycle-dependent genes in growth-arrested rat 3Y1 cells

When growth-arrested 3Y1 cells (Fischer rat fibroblasts) were exposed to 3 X 10(-5) M colchicine, they entered S phase after a 12-h lag period which is the same as that in serum-stimulated cells. The expression of genes such as c-fos, c-myc, JE, KC, ornithine decarboxylase, and histone H3, analyzed by Northern blotting, increased in a cell-cycle dependent manner after colchicine treatment. The increased level of mRNAs was much smaller in colchicine-stimulated cells than in serum-stimulated cells, corresponding to the lower frequency of the former cells entering S phase. The course of the prereplicative phase seems to be similar in terms of the expression of cell cycle-dependent genes in cells stimulated with colchicine and in those stimulated with serum.     

Purification and characterization of erythroid differentiation factor (EDF) isolated from human leukemia cell line THP-1

We isolated a protein, from a cell line of human origin, which exhibits extensive differentiation inducing activity toward Friend leukemia cells. The protein, called Erythroid Differentiation Factor (EDF), was found in a 4 day culture of THP-1 cells performed in the presence of 4 beta-phorbol 12-myristate 13-acetate(PMA). EDF is a homodimer of a molecular weight of 25,000, with an NH2-terminal sequence identical to that of the beta A-chain of porcine Inhibin. It was suggested that a single protein species is responsible for the activities of both EDF and FRP, a FSH releasing protein isolated from porcine ovarian follicular fluid.