Determination of trace levels of fatty acid metal salts by high-performance liquid chromatography with fluorescence prelabeling

A simple method is described for picomole determinations of fatty acid metal salts. Fatty acid salts are directly labeled with 4-bromomethyl-7-methoxycoumarin in the presence of excess ethylenediaminetetraacetic acid tripotassium salt without any solvent extractions. The fluorescence derivatives of fatty acids are separated by reverse-phase high-performance liquid chromatography followed by fluorometric detection. The response of each fatty acid (C8-C18) calcium salt is linear from 1 to 50 micrograms/ml of samples. The detection limit is about 7 pmol. Good recoveries are obtained for the calcium salts of myrystic acid and soap (C8-C18, C18:1,2). The new method is successfully applied to the study on biodegradation of fatty acids in river water.     

Tactical Voting in Plurality Elections

How often will elections end in landslides? What is the probability for a head-to-head race? Analyzing ballot results from several large countries rather anomalous and yet unexplained distributions have been observed. We identify tactical voting as the driving ingredient for the anomalies and introduce a model to study its effect on plurality elections, characterized by the relative strength of the feedback from polls and the pairwise interaction between individuals in the society. With this model it becomes possible to explain the polarization of votes between two candidates, understand the small margin of victories frequently observed for different elections, and analyze the polls'' impact in American, Canadian, and Brazilian ballots. Moreover, the model reproduces, quantitatively, the distribution of votes obtained in the Brazilian mayor elections with two, three, and four candidates.     

Effect of adrenergic agonists and antagonists on alanine amino transferase,fructose-1:6-bisphosphatase and glucose production in hepatocytes

Using rat hepatocytes we confirmed our previous results that glucagon and -adrenergic agonists increased the enzyme activity of alanine aminotransferase (AAT) and propranolol abolished their effects. Only the enzyme activity was measured and other parameters like quantity of the enzyme or activation due to modification were not looked for. As in perfusion experiment phenylephrine and phenoxybenzamine (-agonist and -antagonist respectively) also increased the AAT activity in isolated rat hepatocytes and propranolol reversed these effects. The additive effect of glucagon and phenoxybenzamine on AAT was also persistant in hepatocyte system.Fructose- 1:6-bisphosphatase (Fru-P₂ase), another key enzyme in gluconeogenic pathway, was elevated by glucagon and other -adrenergic agonists both in liver perfusion and isolated hepatocyte experiments and was brought back to the normal level by propranolol. In this case also only the enzyme activity was measured and no other parameters were looked for. Unlike AAT this enzyme was not stimulated by phenylephrine or phenoxybenzamine. But AAT and Fru-P₂-ase activities were increased significantly by adenylate cyclase activators like fluoride or forskolin. Thus, it appears that the regulation of fru-P₂-ase by glucagon is purely a -receptor mediated process whereas AAT activation shows a mixed type of regulation where some well known -agonist and antagonists are behaving as -agonists.Results further indicate the presence of phosphodiesterase in hepatocyte membrane which was stimulated by glucagon and brought back to the normal level by propranolol.The different adrenergic compounds stated above, not only modified the activity of the above two enzymes but also stimulated glucose production by hepatocytes from alanine which was in turn abolished by propranolol as well as amino oxyacetate (AOA), a highly specified inhibitor of AAT. This confirm the participation of AAT in gluconeogenesis from alanine in liver. Forskolin and fluoride also increased the glucose production from alanine and showed additive effects with glucagon, phenylephrine and phenoxybenzamine.     

Effect of glucagon and some other alpha and beta adrenergic agonists and antagonists on alanine amino transferase of perfused rat liver

Summary Glucagon increased alanine amino transferase (AAT) activity in perfused rat liver by about 90% over control. Propranolol, the beta receptor antagonist, abolished the effect of glucagon on this enzyme. Well known beta receptor agonists like isoproterenol, norepinephrine and epinephrine also increased the enzyme activity under identical condition and the enhancement was similarly abolished by propranolol. These experiments suggest that the effect of glucagon on AAT was mediated through beta adrenergic receptor. However, the interesting observation was that phenylephrine, alpha receptor agonist and phenoxybenzamine and tolazoline, two alpha receptor antagonists, increased the AAT activity like glucagon in perfusion experiments and the effects of all these three agents were also abolished by propranolol. Glucagon, when perfused with phenoxybenzamine showed some additive effect. From all these results we are proposing that in our system phenoxybenzamine is acting as beta agonist although it is known to be an alpha antagonist.     

Untargeted mutagenesis induced by UV in the lacI gene of Escherichia coli

Summary Using a nonselective method, we have estimated the proportion of untargeted mutations in the lacI gene of E. coli by transferring either irradiated or unirradiated F pro lac plasmids from an excision deficient donor to an excision deficient pro lac deleted recipient that had been irradiated and allowed to induce recA dependent functions for 30 min. We find that about 10 percent of the mutations induced by either 3.5 Jm^-2 or 7 Jm^-2 UV are untargeted.     

New mutations affecting induced mutagenesis in yeast

Previously isolated mutations in baker's yeast, Saccharomyces cerevisiae, that impair induced mutagenesis were all identified with the aid of tests that either exclusively or predominantly detect base-pair substitutions. To avoid this bias, we have screened 11 366 potentially mutant clones for UV-induced reversion of the frameshift allele, his4–38, and have identified 10 mutants that give much reduced yields of revertants. Complementation and recombination tests show that 6 of these carry mutations at the previously known REV1, REV1 and REV3 loci, while the remaining 4 define 3 new genes, REV4 (2 mutations), REV5 and REV6. The rev4 mutations are readily suppressed in many genetic backgrounds and, like the rev5 mutation, impart only a limited deficiency for induced mutagenesis: it is likely, therefore that the REV4⁺ and REV5⁺ gene functions are only remotely concerned with this process. The rev6 mutants have a more general deficiency, however, as well as marked sensitivity to UV and an increased spontaneous mutation rate, properties that suggest the REV6 gene is directly involved in mutation induction. The REV5 gene is located about 1 cM proximal to CYC1 on chromosome X.     

The finding of Enterobius vermicularis eggs in pre-Columbian human coprolites

Enterobius vermicularis eggs were found in human coprolites collected in the archaeological site of Caserones, Tarapaca Valley, Chile, dating from 400 BC to 800 AD. The human pinworm had already been found in other pre-historic archaeological sites in America, and its introduction in this continent is discussed.     

Fine Structure Mapping in Yeast with Sunlamp Radiation

The X-ray mapping procedure of Manney and Mortimer (1964) is the most widely applicable and convenient method for fine structure analysis in yeast, but suffers the disadvantage that suitable X-ray machines or gamma ray sources are very expensive. Although many other recombinogens are known, none gives a linear dose-response like X-rays and few are as convenient or give as reproducible results. Experiments with Saccharomyces cerevisiae reported in this paper show, however, that the near-ultraviolet radiation emitted by fluorescent sunlamps gives linear dose-response relations, as reproducible results as ionizing radiations, and map distances which correlate highly with those obtained by using (60)Co gamma rays. It is suggested that this convenient recombinogen may be a suitable low-cost substitute for ionizing radiations in fine structure mapping.     

Genetic structure of natural populations ofDryas iulia (Lepidoptera: Nymphalidae) revealed by enzyme polymorphism and mitochondrial DNA (mtDNA) restriction fragment length polymorphism (RFLP)

Dryas iulia appears to have undergone a mode of evolution different from that of other members of its subfamily (Heliconiinae). While other species constitute highly subdivided and inbred populations, those ofD. iulia are thought to be large and uniform. Analyzing six samples from Southern Brazil (state of Rio Grande do Sul) in relation to three enzyme systems (EST, LAP, and PGM) and their mtDNA RFLP patterns, we found that they are very similar at the molecular level. TheF statistics for enzyme polymorphism data revealed that inbreeding makes a great contribution to the population homozygosity, sinceF _IS equals 0.1322 andF _ST equals 0.0023. Since the chi-square test showed thatF _ST is not significant, we conclude that all localities belong to the same population. The mtDNA differentiation was about 12 times greater than for nuclear genes;F _ST was equivalent to 0.0265. We suggest that this difference is due to a higher dispersal of males, in relation to females.