Polyamine levels during the onset of "CAM" inOpuntia F. indica (Miller).

Polyamines have been related to the "Crassulacean Acid Metabolism" (CAM) in higher plants. Such relationship was however observed in plants where CAM activity is inducible by external factors. Results presented here indicate that, inOpuntia F. indica, cladodes where onset of CAM is dependent on internal conditions, i.e. leaf age, the concentration of putrescine increases in parallel to the acidity of the cytoplasm. The parallel increase of putrescine concentration and acidity (malic acid concentration) can be best evaluated during the onset of CAM (young cladodes), while such correlation is not observed in mature cladodes where CAM is already in it's full function. Spermidine and spermine show no correlation with CAM activity neither during the onset of CAM nor during it's full function. However, spermidine levels correlate negatively to CAM activity when cladodes attain > 30 days of age. The results suggest that putrescine in free form could possibly counteract the increase of cellular acidity during onset of CAM inOpuntia F. indica; the possible roles of spermidine are discussed.

Synthesis of substituted DL-3(5-benzazolyl)alanines as dopa and alpha-methyldopa analogs and their effects on dopamine beta-hydroxylase, tyrosinase and diphenoloxidase.

The influence of bioisosteric replacement of catechol moiety of L-Dopa and alpha-Methyldopa with benzimidazole and benzotriazole ring has been examined on dopamine beta-hydroxylase and tyrosinase, in order to evidentiate an inhibitory activity on the synthesis of catecholamines and a possible antihypertensive action. The preliminary results obtained so far showed that inhibition of dopamine hydroxylase occurs at 5 x 10(-4) M concentration for the most active compounds bearing a trifluoromethyl group in the azole ring (2a,c). An analogous result was observed in the case of tyrosinase inhibition with compound 2c, while other compounds (2a,e) were equiactive (92% inhibition) at higher concentration (1 x 10(-3) M). Compound 2c was also the most active in inhibition of diphenoloxidase (83% at 6 x 10(-5) M concentration).

Leucine-enkephalin increases the level of inositol (1,4,5) triphosphate and releases calcium from an intracellular pool in rat ventricular cardiac myocytes.

In rat ventricular cardiomyocytes loaded with the fluorescent Ca2+ indicator Indo-1/AM, the delta opioid receptor agonist Leu-Enk caused Cai oscillations and abolished the caffeine-induced Cai transient. During superfusion of cardiomyocytes with the specific opioid antagonist naloxone, Cai is not affected by Leu-Enk and the caffeine-triggered Cai transient is preserved. In parallel experiments with cardiac myocytes, the delta opioid agonist increased the intracellular level of Ins (1,4,5) P3 by about 4 times above the control value. Such an effect was completely antagonized by naloxone. Thus, Leu-Enk induces depletion of Ca2+ from the SR by a receptor-mediated mechanism which appears to involve an increase in the intracellular level of Ins (1,4,5) P3.

[Peptidase activity and toxicity of strains of Pseudomonas aeruginosa]. / Attività peptidasiche e tossicità in ceppi di Pseudomonas aeruginosa.

Pseudomonas aeruginosa is a microorganism of the terrestrial and aquatic environment which may cause pulmonary, urinary and corneal infections. The pathogenesis of Pseudomonas-induced diseases seems to be linked to the production of extracellular substances such as exotoxins, hemolysins, leukocidins and hydrolytic enzymes, including various peptidases. Anyway there is not a clear view on the role other proteases have in the mechanism of pathogenesis, and even if their activity may always be associated to the toxicity of the microorganism. We have therefore determined the activity of a number of eso- and endopeptidases in 17 strains of P. aeruginosa isolated from patients with urinary pathologies. Four of these peptidase activities, namely elastase, neutral protease, aminopeptidase I and leucine aminopeptidase show a positive correlation with three parameters selected as indices of toxicity, i.e. the mucoid appearance, the gentamicin resistance and the adhesivity of colonies.

[Metabolism of ornithine in human gingival tissue]. / Metabolismo dell'ornitina in tessuto gengivale umano.

The behavior of two enzymes of the ornithine pathway, leading to the formation of proline and, eventually, of collagen, arginase and ornithine oxo-acid aminotransferase has been investigated in normal and inflamed gingival tissue. Both enzymatic activities show a statistically significant decrease in pathological samples as compared to normal ones. The data on arginase activity may be in agreement with the already documented low level of urea in pathological gingival fluid, while a decrease of the ornithine aminotransferase activity could be linked to the phenomenon of gingival retraction, i.e. the lack of complete regeneration of gingival tissue usually observed in chronically inflamed subjects, that would be reasonably parallel to a decreased proline/collagen synthesis.

[Genetic improvement in Vicia faba and favism. I. Distribution and levels of presumably hemolytic metabolites]. / Miglioramento genetico in Vicia faba e favismo - I. Distribuzione e livelli di metaboliti presumibilimente emolitici.

Covicine + vicine, L-DOPA-glucoside + L-DOPA and ascorbic acid were determined in different lines of Vicia faba beans throughout the biological cycle of the plant. As the seed matures the levels of convicine + vicine as well as of ascorbic acid decrease with seed maturation in all the lines examined. L-DOPA, which is lacking in cotyledons but present in the tegument, also decrease and is nearly undectable in some lines with white flowers.

[Genetic improvement in Vicia and favism. II. Glycosidase activity]. / Migliogramento genetico Vicia faba e favismo - II. Attività gliccosidasiche.

Glycosidase activities with starch and PNP-glycosides as substrates can be detected in the cotyledons, leaves, pods and teguments of Vicia faba beans. The mainly hydrolize alpha- and beta-glucosides, alpha- and beta-galactosides as well as starch. The amylase activity arises at very early stages of seed maturation and then rapidly decreases, whereas glycosidases increase up to the 30% of the beans dry weight before decreasing. The beta-glucosidase might play a role in regulating the metabolism of possibly haemolitic glycosides (i.e. vicine, convicine and L-DOPA glucoside) thus explaining the presence of this enzyme.

[Arginase characteristics in an ammoniotele]. / Caratteristiche dell'arginasi di un organismo ammoniotelico.

Arginase (EC 3.5.3.1.) is active in the hepatopancreas, gills and pincer muscle of the ammoniotele Carcinus maenas. Its activity in the hepatopancreas is mainly localized in mitochondria. The enzyme becomes inactive at 37 degrees C if the assay is carried out without previous incubation with Mn2+; the optimum temperature for the fully activated enzyme is 47 degrees C. Two fractions showing arginase activity can be separated on DEAE-cellulose at pH 8.3, the most active being eluted by a linear gradient of KCl at a concentration of 0.3 divided by 0.4M, the other with a buffer front. Since ornithine transaminase (EC 2.6.1.13.) activity has been detected in the hepatopancreas, arginase activity in this organ is possibly related to ornithine catabolism leading to proline and glutamate.

Urea cycle enzymes in the liver of a dolphin Platanista indi.

Urea cycle enzymes are all shown to be active in dolphin liver. Acetylglutamate-independent cytoplasmic carbamylphosphate synthase is also present. Arginase is a basic protein, although less markedly basic than the dog enzyme. It is 118 per cent activated by heating at 50 degrees. Optimum pH is 10.5. Co++ and Ni++ inhibit the enzyme. AMP deaminase, glutamicoxaloacetic transaminase, glutamate dehydrogenase and ornithine transaminase are also active in dolphin liver.