Metabolic adaptation of renal carbohydrate metabolism. V.In vivo response of rat renal-tubule gluconeogenesis to different diuretics

We have studied the effects of the diuretics mersalyl, furosemide and ethacrynic acid on renal gluconeogenesis in isolated rat-kidney tubules and on the activities of the most important gluconeogenic and glycolytic enzymes in both fed and fasted rats. Mersalyl (15 mg.kg^–1 animal weight) significantly decreased the rate of gluconeogenesis in well-fed rats (68%) as well as in 24 and 48-h fasted ones (33 and 37% respectively). This inhibition occurred when lactate, pyruvate, glycerol or fructose were used as substrates. Ethacrynic acid at a dose of 50 mg.kg^–1 animal weight provoked a transient inhibition of renal glucose production by almost 20% but only in fed rats with lactate as substrate, whereas the same dose of furosemide did not affect this metabolic pathway.Parallel to these changes, mersalyl caused a significant inhibition in the maximum activity of the most important gluconeogenic enzymes, phosphoenolpyruvate carboxykinase, fructose 1,6-bisphosphatase and glucose 6-phosphatase, in both fed and fasted rats. Neither ethacrynic acid nor furosemide produced any variations in the activities of these enzymes. The activity of the glycolytic enzymes phosphofructokinase and pyruvate kinase was not modified by these diuretics. Nevertheless, the activity of the thiol-enzyme glyceraldehyde 3-phosphate dehydrogenase was severely inhibited by mersalyl and to a lesser extent by the other diuretics. This inhibition was higher in fasted than fed rats. Hence, we conclude that the inhibitory effect of mersalyl on renal gluconeogenesis is due, at least partly, to a decrease in the flux through the gluconeogenic enzymes. Blood glucose was not modified after diuretic treatment in fed animals whereas mersalyl decreased the levels of blood glucose in 24-h fasted rats. Thein vivo effects of diuretics on gluconeogenesis correlate well with the previously observedin vitro effects, although ethacrynic acid was less potent as an inhibitorin vivo, probably because of its rapid clearance.Abbreviations EDTA ethylenediaminetetraacetic acid - EGTA ethyleneglycolbis (-aminoethylether) N,N,N,N-tetraacetic acid - DTT dithiothreitol - HEPES N-2-hydroxyethylpiperazine-N-2-ethanesulfonic acid - TRIS 2-amino-2-hydroxymethyl-1,3-propanediol Publication No. 166 from Drogas, Tóxicos Ambientales y Metabolismo Celular Research Group, Department of Biochemistry and Molecular Biology, University of Granada, Granada, Spain     

Immunocytochemical identification of photoreceptor proteins in hypothalamic cerebrospinal fluid-contacting neurons of the larval lamprey (Petromyzon marinus)

Antibodies directed against different visual pigment opsins, and an antibody raised against the C terminal of the -subunit of retinal G protein (transducin) labelled cerebrospinal fluid-contacting cells located within the hypothalamus (postoptic commissural nucleus and ventral hypothalamic nucleus) of ammocoete lampreys (Petromyzon marinus). These antibodies also labelled photoreceptor cells within the retina and the pineal and parapineal organs, but no other areas of the brain. Despite considerable behavioural and physiological evidence for the existence of deep brain photoreceptors, numerous studies have failed to identify photoreceptor proteins within the basal brain. The results presented in this paper support our recent results in the lizard Anolis carolinensis, suggesting that a group of cerebrospinal fluid-contacting neurons within the vertebrate brain have a photosensory capacity. We speculate that these cells mediate extraocular and extrapineal photoreception in nonmammalian vertebrates.     

Ontogeny of some endocrine cells of the digestive tract in sea bass (Dicentrarchus labrax): An immunocytochemical study

Serotonin- and ten peptide-immunoreactive (IR) cell types were identified in the digestive tract of sea bass (Dicentrarchus labrax L.) larvae of four morphofunctional phases ranging in age from hatching to 61 days. The sequence of appearance and location of endocrine cells during ontogenetic development of the larvae was determined. The differentiation of endocrine cells followed a distal-proximal gradient in the gut which paralleled the morphofunctional differentiation. Serotonin-IR cells were identified in the last portion of the digestive tract from phase I onwards and in the gastric region from phase III, before these regions were morphofunctionally differentiated; met-enkephalin-IR cells were identified from phase II onwards in both the differentiated rectum and the undifferentiated intestine; cholecystokinin (CCK)- and synthetic human gastrin-34-IR cells were located only in the intestine and first found in the undifferentiated intestine of phase II; human gastrin-17-, peptide YY (PYY)- and neuropeptide Y (NPY)-IR cells appeared in the intestine from phase II and in stomach in phase IV, when it showed gastric glands; pancreatic polypeptide (PP)- and glucagon-IR cells were observed in both intestine and stomach, but insulin- and somatostatin-IR cells only in stomach, from phase III, during which the intestine but not the stomach was differentiated. PP- and PYY-, PP- and glucagon-, and PYY- and glucagon-like immunoreactivities coexisted from their first appearance in some cells of the gut.     

Purification of amoebolytic substances from Bacillus licheniformis M-4

Three antibiotic peptides with amoebolytic activity have been purified from culture supernatants of Bacillus licheniformis M-4 (amoebicins m4-A, m4-B, and m4-C). They were hydrophilic peptides consisting of six different amino acids (Asp, Glu, Ser, Thr, Pro, Tyr). Their molecular weights ranged from 3,000 to 3,200. Purified amoebicins were active against human pathogenic and non-pathogenic strains of Naegleria. They also showed a broad antifungal spectrum, but a narrow antibacterial activity.Abbreviations (TFA) Trifluoroacetic acid     

Effect of the new fluorescent brightener Rylux BSU on morphology and biosynthesis of cell walls in Saccharomyces cerevisiae

Rylux BSU, a new fluorescent brightener from the family of 4,4-diaminostilbene-2,2disulfonic acid derivatives, inhibited growth and cytokinesis of the yeast Saccharomyces cerevisiae. In the presence of 0.1–1 mg/ml Rylux BSU the cells grew in clumps, had irregular shape and were larger than controls. They formed apparently normal primary septa but their secondary septa and lateral cell walls, especially those in older cells, were abnormally thick with large deposits of amorphous wall material in the periplasmic spaces all over the cell surface. Chitin content in the cell walls of cells grown in the presence of Rylux BSU was increased 2 to 5 times in comparison to that of the controls and glucan content was reduced by up to 30%. In the in vitro assays with particulate membrane fractions, Rylux BSU acted as a non-competitive inhibitor of -1,3-glucan synthase with inhibitory constant K _i=1.75 mg/ml whereas the chitin synthase was inhibited to a much lesser extent. From the difference of the effects of Rylux BSU on the synthesis of chitin in vivo and in vitro it is concluded that the brightener interacts with chitin synthase only indirectly, possibly by influencing the properties of integral plasma membrane.Abbreviations RBSU Rylux BSU, 1,4-benzenedisulfonic acid-2,2-[ethyleneidy]bis[(3-sulpho-4,1-phenylene)imino[6-bis(2-hydroxyethyl)amino]-1,3,5-triazine-4,2-diylamino]]bis-, hexasodium salt - FB fluorescent brightener     

Dendritic arbor alterations in the medial superior olivary neurons of neonatally underfed rats

Golgi-Cox-stained bipolar cells of the medial superior olive (MSO) were analyzed in control and undernourished Wistar strain rats at 12, 20, 30 and 40 days of age. Undernutrition significantly reduced the number of dendrites and the extension of ipsilateral dendritic prolongations, with no effects upon the cross-sectional somal area and minimal alterations in the corresponding contralateral dendritic branches. The data suggest that in underfed rate, afferents from the receptors projecting to the MSO via the anteroventral cochlear nuclei may cause an imblance in the binaural interactions which occur between the axon terminals and the ipsilateral contralateral dendritic arbors of MSO neurons.     

Thermodynamic study of motor behaviour optimization

Our work is aimed at studying the optimization of a complex motor behaviour from a global perspective. First, free climbing as a sport will be briefly introduced while emphasizing in particular its psychomotor aspect called route finding. The basic question raised here is how does the optimization of a sensorimotoricity-environment system take place. The material under study is the free climber's trajectory, viewed as the signature of climbing behaviour (i.e., the spatial dimension). The concepts of learning, optimization, constraint, and degrees of freedom of a system will be discussed using the synergistic approach to the study of movement (Bernstein, 1967; Kelso, 1977). Measures of a trajectory's length and convex hull can be used to define an index whose equation resembles that of an entropy. This index is a measure of the trajectory's overall complexity. Some important concepts related to the thermodynamics of curves will also be discussed. The optimization process will be studied by examining the changes in entropy over time for a set of trajectories generated during the learning of a route (ten successive repetitions of the same climb). It will be shown that the entropy of the trajectories decreases as learning progresses, that each level of expertise has its own characteristic entropy curve, and that for the subjects tested, the mean entropy of skilled climbers is lower than that of average climbers. Basing our analysis on the concepts of degrees of freedom and constraint equations, an attempt is made to relate trajectory entropy to system entropy. Based on the postulate that trajectory entropy is equal to the difference in entropy between the unconstrained and constrained system, a model of motor optimization is proposed. This model is illustrated by an entropy graph reflecting a dynamic release process. In the light of our results, two opposing views will be examined: movement construction vs. movement emergence.     

Genetics and gibberellin production inGibberella fujikuroi

Gibberella fujikuroi (Fusarium moniliforme) is a complex group of plant pathogens. Some strains produce gibberellic acid and other gibberellins that promote growth and regulate various stages in plant development.The paper describes the research effort directed to development of genetic tools for this species. Furthermore the main features of the gibberellin biosynthetic pathway as established in Gibberella are described.Abbreviations AMO 1618 2-isopropyl-4-(trimethylammonium chloride)-5-methylphenylpiperidine-1-carboxylate - hydroxykaurenoic acid ent-kaur-16-en-7-ol-19-oic acid - kaurenal ent-kaur-16-en-19-al - kaurene ent-kaur-16-ene - kaurenoic acid ent-kaur-16-en-19-oic acid - kaurenol ent-kaur-16-en-19-ol - paclobutrazol 1-(4-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-lyl)pentan-3-ol - pefurazoate pent-4-enyl-N-furfuryl-N-imidazol-1-ylcarbonyl-DL-homoa laninate - tetcyclacis 5-(4-chlorophenyl)-3,4,5,9,10-pentaazatetracyclo-5,4,10^2.6,O^8.11-dodeca-3,9-diene - triarimol -(2,4-dichlorophenyl)--phenyl-5-pyrimidine methyl alcohol     

The influence of pH on growth kinetics of yeasts in the presence of benzoate as a sole carbon source

The inhibitory effect and substrate properties of benzoic acid were estimated for 25 yeast strains belonging to generaCondida, Hansenula, Hypopichia, Rhodosporidium, Rhodotorula, Saitoella andTrichosporon. Benzoic acid can serve as a sole carbon source for growth of yeasts belong to generaRhodotorula, Rhodosporidium andSaitoella in synthetic mineral media. Specific growth rate is strongly dependent both on the concentration of benzoate and the pH value of the cultivation media. Maximum specific growth rate on benzoate is observed in alkaline cultivation media at pH 7.0–7.5 whereas those for growth on glucose in mildly acidic media at pH 5.0. Some of the strains showed weak growth on benzoate even at pH 8.5. Some carotenoid-containing yeasts of the generaRhodotorula andRhodosporidium lost their ability to synthesize carotenoid pigments during growth in alkaline benzoate media.