Direct micro-sequence analysis of peptides from Escherichia coli ribosomal proteins S11, L9 and L29 after separation by reversed phase chromatography

Tryptic peptides of the ribosomal proteins S11, L9 and L29 were separated by reversed phase chromatography under conditions which enabled direct micro-sequencing with the 4-(dimethylamino)azobenzene-4'-isothiocyanate/phenylisothiocyanate double coupling method [Chang, Brauer, Wittmann-Liebold (1978) FEBS Lett. 93, 205-214]. The peptides were separated on a RP-18 column employing volatile buffers at pH 2.0, 4.1 and 7.8. Depending on the different chromatographic behaviour of the peptide mixture, the elution gradient was optimised for each hydrolysate using 20 micrograms of the hydrolysed protein. Preparative separations were made with 150-250 micrograms. At least 80% of the peptides could be isolated by these techniques and used for direct micro-sequencing without further purification or desalting. The results show that the high-performance liquid chromatographic method employed allows easy isolation and sequencing with minute amounts of peptides.     

Surface-active properties of antibiotics

The critical concentrations of the mycella formation of novobiocin, mithramycin, variamycin, erythromycin, oleandomycin and lincomycin were determined with two methods by changes in the isotherms of the surface tension and in the maximum absorption of rodamine due to the antibiotic concentrations. The results obtained with the two methods were comparable.     

Cloned nodulation genes of Rhizobium leguminosarum determine host-range specificity

Summary Three nodulation-deficient (nod) mutants of Rhizobium leguminosarum were isolated following insertion of the transposon Tn5 into pRL1JI, the R. leguminosarum plasmid known to carry the nodulation genes. DNA adjacent to the nod: Tn5 alleles was subcloned and used to probe a cosmid clone bank containing DNA from a Rhizobium strain carrying pRL1JI. Two cosmid clones which showed homology with the probe contained about 10 kb of DNA in common. The R. leguminosarum host-range determinants were found to be present within this 10 kb common region since either of the cosmid clones could enable a cured R. phaseoli strain to nodulate peas instead of Phaseolus beans, its normal host. Electron microscopy of nodules induced by Rhizobium strains cured of their normal symbiotic plasmid but containing either of the two cosmid clones showed bacteroid-forms surrounded by a peri-bacteroid membrane, indicating that normal infection had occurred. Thus it is clear that this 10 kb region of nodDNA carries the genes that determine host range and that relatively few bacterial genes may be involved in nodule and bacteroid development.     

Conversion of sterigmatocystin to aflatoxin B 1 by Aspergillus parasiticus

¹⁴C-Sterigmatocystin isolated from cultures of $\text{Aspergillus}$$\text{versicolor}$ supplemented with (1-¹⁴C)acetate was shown to be efficiently converted to aflatoxin B₁ by the resting mycelium of $\text{A. parasiticus}$. The experimental results may indicate a biosynthetic pathway leading from 5-hydroxysterigmatocystin to sterigmatocystin and then to aflatoxin B₁.     

α1-Adrenergic Receptor Mediates Arachidonic Acid Release in Spinal Cord Neurons Independent of Inositol Phospholipid Turnover

The alpha 1-adrenergic receptor has been shown to mediate the release of arachidonic acid in FRTL5 thyroid cells and MDCK kidney cells. In primary cultures of spinal cord cells, norepinephrine stimulated release of arachidonic acid (from neurons only) and turnover of inositol phospholipids (from neurons and glia) via alpha 1-adrenergic receptors. These two responses were dissociated by treatment with phorbol ester and pertussis toxin, which inhibited production of inositol phosphates with no appreciable effect on release of arachidonic acid. Extracellular calcium was required for release of arachidonic acid, but not for production of inositol phosphates. The calcium channel blockers nifedipine and verapamil inhibited release of arachidonic acid only. However, 8-(N,N-diethylamino)octyl-3,4,5-trimethoxybenzoate (TMB-8), a compound that blocks intracellular calcium release, diminished production of inositol phosphates, but had little effect on release of arachidonic acid. These results suggest that alpha 1-adrenergic receptors couple to release of arachidonic acid in primary cultures of spinal cord cells by a mechanism independent of activation of phospholipase C, possibly via the activation of phospholipase A2.     

Three separate mitochondrial DNA sequences are contiguous in human genomic DNA

We isolated from a HeLa genomic library 38 plaques that hybridized to total mitochondrial (mt) DNA isolated from human placenta. One clone (HLmt-17.8) hybridized to a 740 base-pair (12 S ribosomal RNA gene and displacement loop) mtDNA probe and was characterized in more detail. Within its 17.8 x 10(3) base-pair insert a 1.6 x 10(3) base-pair mtDNA fragment was similar to three non-sequential coding genes of human mtDNA, including a part of the 12 S ribosomal RNA (684-971), the cytochrome oxidase I (6553-7302), and two NADH dehydrogenase [ND4L/ND4] (10,606-11,159). The similarity to human mtDNA sequences was 92.0%, 92.3% and 92.4%, respectively, the highest degree of similarity to human mtDNA so far reported. This is also the first report of several adjacent mtDNA-like sequences in cellular chromosomes. The mtDNA-like sequences in HLmt-17.8 was found in the DNAs of human placenta, freshly isolated human leukocytes, foreskin and several human cell lines; but it was not present in other primates or lower organisms. The HLmt-17.8 mtDNA-like region appears to be a pseudogene that transferred into the nucleus in humans more recently than nine million years ago.     

Modeling the acquisition of counting with an associative network

In the acquision of counting by children, there are three interesting phenomena (Fuson et al. 1982): (1) the number word sequence produced by children can be divided into three distinct portions, called the conventional, stable nonconventional, and unstable portions; (2) irregular number words such as fifteen are omitted more often than regular ones such as fourteen, sixteen, and seventeen; and (3) initially the number word sequence is in a recitation form, rather than in the form of an associative chain of separable serial elements. Our paper at first analyzes these phenomena from the viewpoint of associative memory by assuming the number word sequences are made up of many associative relationships between the number words. This assumption is not contradictory to the third phenomenon described above, because the associative relationships are not confined only to those between the serial number words. On the basis of these anaylses, an associative network model, HAPS proposed by one of the authors (Hirai 1983), is extended so that it can mimic some aspects of the learning of sequence which involves the above three phenomena. The learning and production of sequence by the network are simulated on a digital computer, and the results show that the three phenomena can be observed in the performance of the network.     

Effect of interferon on the course of experimental E coli-induced pyelonephritis

The effect of the type I interferon on the development and process of experimental pyelonephritis caused by E. coli was studied on mice weighing 12 to 14 g. Interferon was administered intraperitoneally in a dose of 1000 units on days 3 and 7 of the disease. It was shown that the administration of the type I interferon to the mice with experimental pyelonephritis promoted rapid elimination of bacteria from the kidneys, prevented their penetration to the contralateral (intact) kidney, prevented marked macro- and microscopic damages in the kidneys, lowered the intensity of the inflammatory reaction, and increased the phagocytic activity of neutrophils and the number of the E-rosette-forming lymphocytes in the thymus. The data provided experimental grounding for clinical trials of interferon preparations in treatment of bacterial pyelonephritis.