The early effects of valproic acid in low doses in liver metabolism

The effect of low doses of valproic acid (VPA), 0.6 mM in arterial blood, in liver metabolism was studied. Twenty four hour fasted rats were infused into the jugular vein with VPA at a dose of 4 mg/kg/min during 50 min. The right carotid artery was also catheterized in order to draw arterial blood samples for determining VPA concentrations and acid-base parameters. After VPA infusion, a tissue sample of liver was obtained and freeze-clamped. VPA did not change the arterial blood acid-base parameters. The liver tissue concentration of pyruvate and alanine increased in VPA group while lactate concentrations did not change. Concentration of glutamine, glutamate, malate, citrate and aspartate in the liver fell significantly. These results suggest that VPA in low doses may modify the hepatic metabolism of the rat in vivo.     

Proteolytic activities in yeast after UV irradiation

Summary Specific proteolytic activities are known to be induced in Escherichia coli following irradiation. Consequently it seemed of interest to investigate whether variations in proteinase activities occur in yeast.Among the five most well known proteinases of Saccharomyces cerevisiae, we have found that proteinase B activity increases up to three times in wild-type RAD ⁺ yeast cells after a dose of 50 Jm^-2 of 254 nm ultraviolet light (40% survival). Carboxypeptidase Y and aminopeptidase I (leucin aminopeptidase) activities were only moderately increased. Proteinase A activity was only slightly enhanced, while aminopeptidase II (lysin aminopeptidase) was unaffected in both RAD ⁺ strains studied.The observed post UV-increase in proteinase B activity was inhibited by cycloheximide and was dose dependent. Increases in proteinase B levels were independent of the activation method used to destroy the proteinase B-inhibitor complex present in the crude yeast extracts.A standard method for comparison of the postirradiation levels among different proteinases, strains and methods of activation is presented.Abbreviations UV Ultraviolet - BRIJ-35 Polyoxyethylene-23-lauryl ether - EDTA Ethylene diamine tetraacetic acid - EGTA Ethylene glycol bis (-aminoethyl ether) tetraacetic acid - MOPS 3-[N-morpholine]propansulfonic acid - HEPES N-2-Hydroxyethylpiperazine-N-2-ethansulfonic acid - Tris Tris(hydroxy methyl)amino methane - BTPNA N-benzoyl-L-tyrosine-p-nitroanilide - CP.Y Carboxypeptidase Y - Leu.AP Leucin amino peptidase - Lys.AP Lysin amino peptidase - DMFA Dimethyl formamide - CHX Cycloheximide - PMSF Phenylmethyl sulfonyl fluoride - TCA Trichloroacetic acid Code Number of Enzymes EC. 3.4.23.8 Proteinase A - EC. 3.4.22.9 Proteinase B - EC. 3.4.12.8 Carboxypeptidase Y - EC. 3.4.24.4 Thermolysin - EC. 3.4.23.1 Pepsin A     

Preference for medium dense grass tussocks byHippodamia convergens [Col.: Coccinellidae]

The preference in the choice of hibernacula of the convergent lady beetle,Hippodamia convergens Guérin-Meneville, was investigated with regard to morphological aspects of 2 introduced range grasses,Panicum coloratum (L.), andEragrostis curvula (Schrad.) Beetles strongly preferred tussocks with a ratio in the range of 1.0–3.0 stems per cm² for lovegrass. Preference for klein grass tussocks ranging from 110–130 stems/clump was found. No preference was shown for a particular tussock circumference. It was demonstrated that tussocks could successfully be designated as suitable for beetle aggregation.     

Are salinas a suitable alternative breeding habitat for Little Terns Sterna albifrons?

This paper describes the breeding population, breeding habitats and reproductive variables of Little Terns Sterna albifrons in natural (sandy beaches) and alternative (salinas) habitats. Studies of nesting success conducted between 1998 and 2002 in these two types of habitat were combined with a literature review of census work from the past 30 years in order to assess whether salinas are suitable alternative breeding habitat for Little Terns. Most of the Portuguese Little Tern population now breeds in salinas. Census data from the last 30 years show that this is a recent breeding behaviour, because until the 1990s most colonies were located on sandy beaches. Destruction and disturbance of the natural habitat has caused this habitat shift. Despite this shift, the Portuguese Little Tern breeding population did not decline during this period and no significant differences were found in nesting success between natural and alternative habitats. This might indicate that salinas are a suitable alternative breeding habitat for Little Terns, but differences in laying period, clutch size and egg size were recorded between birds nesting on sandy beaches and in salinas in the same area. Birds nested earlier on sandy beaches and laid larger clutches and eggs than in salinas. These data suggest that, when both habitats are available, older and/or higher quality birds prefer sandy beaches for breeding, presumably trying to re-nest in salinas when first breeding attempts failed. We discuss conservation priorities and management actions for both habitats.     

Spatial and Temporal Variation of Macroinvertebrate Drift in Two Neotropical Streams1

The detection of spatial variation in macroinvertebrate drift depends on the spatial scale of investigation in streams of the La Selva Biological Station, Costa Rica. Drift samples were taken in a spatially nested design, with two streams, two reaches per stream, two riffles per reach, and four replicate samples per riffle. Drift showed little variation among streams, but varied significantly at the scales of reach and riffle, with variation among samples also high. In addition, sampling took place at two temporal scales: diel and at two different periods that differed in rainfall conditions. Drift diel periodicity was a clear pattern, while only density of individuals varied among sampling periods. This is the first study of macroinvertebrate drift at multiple spatial scales, despite the recognition that multi‐scale studies are essential for a more complete understanding of community patterns and processes.     

Non-polluting wood and pulp delignification: Biomimetic ligninase system

Summary We report the delignification ofPinus radiata D Don,Eucalyptus globulus andEucalyptus grandis woods (formic acid treated and untreated) by 2 h treatment with a hemin/hydrogen peroxide system. The untreated chips and sawdust ofE. globulus were 30% and 50% delignified respectively. No significant effects were found forP. radiata sawdust;P. radiata treated chips (organosolv pulp) did not show any further delignification upon hemin/peroxide action, 25% delignification was achieved in untreated chips. In the case ofE. grandis untreated wood the delignification was better in sawdust than in chips, but in smaller percentage than in the otherEucalyptus species. This relation is maintained in substrates, treated with formic acid or untreated. The delignification of chips in both species ofEucalyptus was improved when they were pre-treated with formic acid. The loss of lignin in theE. grandis andE. globulus sawdust (pre-treated with formic acid) was 79% and 75% respectively.     

Time course and subcellular distribution of the radioactivity in a synaptic terminal after supplying the perikaryon with labelled glutamic acid

Summary The cell bodies of the preganglionic neurons of the chick ciliary ganglion were supplied with ³H-glutamic acid by intracerebral injection. The ciliary ganglia were studied with light and E.M. radioautography at 3, 18, 24 hours, 2, 6 and 16 days after injection. The reaction in the ganglion was intense over the preganglionic structures but very weak over the ganglionic cell bodies. The reaction increased in intensity from the myelinated region toward the ending; within the axon, the radioactivity was rather peripheral during early stages and more evenly distributed from the second day onward. The ending showed two peaks of radioactivity, at 18 hours and at 6 days; these peaks are interpreted as the accumulation of material which arrived in two phases; the first with an average velocity greater than 80 mm/ day and the second with a velocity of 2–5 mm/day. Within the nerve ending, the material transported in the fast phase was associated preferentially with the axoplasm rich in synaptic vesicles, close to the synaptic region, whereas the material transported in the slow phase was associated rather with mitochondria and the axoplasm devoid of synaptic vesicles that lies away from the synaptic surface. In contrast to what is observed with lysine, the density of the reaction on the preterminal axons was much lower than that on the endings. It is suggested that a protein rich in glutamyl residues with a rather long mean-life is transported to the ending in the fast phase.On leave from the Catholic University, Santiago, Chile.Supported by Institut National de la Santé et de la Recherche Médicale, France and IBRO. Acknowledgement. I express my sincere thanks to Dr. B. Droz for his hospitality and for helpful discussions throughout the work.     

Assembly of microspheres from acidic proteinoids and histones or histone-like proteinoids

Basic polyamino acids, whether organismic or synthetic in origin, alter the morphology of proteinoid microspheres in which they are included. The particles obtained with histone are essentially indistirguishable under the light microscope from those obtained with proteinoids of histone-like composition (histonoids). In each instance, structures of morphological complexity similar to those of some microfossils are obtained.     

Brote epidemico de tinea corporis por Microsporum gypseum

Summary A small epidemic of tinea corporis due to M. gypseum is reported. There were 13 children affected, ages 1–15 years. These children belonged to 6 neighbouring families and all used a common playground, an empty lot located nearby. Cultures were positive for M. gypseum in the 13 children and the agent was also isolated from 2 soils collected in the playing-ground. Soil isolates were classified as N. gypsea. Clinically, the lesions were circinated and had active borders, they were preferentially located in the trunk. Most children (8/13) had multiple lesions. These and other pertinent aspects are discussed in the text.     

Susceptibility to mercurials of clinical Pseudomonas aeruginosa isolated in México

Susceptibility to inorganic mercuric ions and to organomercurials of 237 Pseudomonas aeruginosa clinical strains isolated in Mexico was determined by agar dilution tests. Resistant strains fell into two classes: i) narrow-spectrum resistant strains (27% of total isolates) resistant only to mercuric ions and to merbromin, and most grouped in pyocin type 1; and ii) broad-spectrum resistant strains (5%) with additional resistances to thimerosal, phenylmercury, methylmercury and p-hydroxymercuribenzoate, that belonged mostly to pyocin type 10. Mercurial resistant isolates showed a higher proportion of resistance to antibiotics and metals than did mercurial sensitive isolates, and broad-spectrum resistant strains had the highest frequency of resistance to antibiotics and to tellurite and arsenate.