Regulation of circulating levels of the crustacean hyperglycemic hormone: evidence for a dual feedback control system

The effects of glutamate, aspartate, glycine, proline, alanine, taurine, glycerol, glucose and lactate injections on the haemolymph levels of the crustancean hyperglycemic hormone and/or glucose and lactate in the shore crab, Carcinus maenas, were investigated. Only glucose and lactate caused significant changes of hyperglycaemic hormone levels. Glucose injections resulted in a drop of both hormone and lactate, while lactate had an opposite effect, i.e. it raised both crustacean hormone and glucose levels. The results suggest that during increases in glycolytic flux, lactate may cause a release of hormone by a positive feedback mechanism. The hormone would then stimulate glycogenolysis, thus increasing glucose availability. If more glucose is released than is metabolized, excess glucose may leak from the cells and suppress crustancean hyperglycemic hormone release from the X-organ/sinus gland complex by negative feedback.Abbreviations ABTS 2,2-azino-bis (3-ethylbenzthiazoline sulphonic acid) - ANOVA one-way analysis of variance - BSA bovine serum albumin - BW body weight - CHH crustacean hyperglycemic hormone - ELISA cnzyme-liked immunosorbent assay - GIH gonadinhibiting hormone - IgG immunoglobin G - MIH moult-inhibiting hormone - MTGXO medulla terminalis X-organ - PB sodium phosphate buffer - PBS phosphate buffered saline - Pi inorganic phosphate - XO-SG X-organ-sinus gland complex     

Evaluation of Probiotic Properties of Novel Brazilian Lactiplantibacillus plantarum Strains

Probiotics and Antimicrobial Proteins - Beneficial effects of Lactiplantibacillus plantarum strains have been widely reported. Knowing that the effects of probiotic bacteria are strain-dependent,...     

Carbon-13 nuclear magnetic resonance analysis of [1-13C]glucose metabolism in Crithidia fasciculata. Evidence of CO2 fixation by phosphoenolpyruvate carboxykinase

The non-invasive technique of 13C nuclear magnetic resonance was applied to study glucose metabolism in vivo in the insect parasite Crithidia fasciculata. It was found that under anaerobic conditions [1-13C]glucose underwent a glycolytic pathway whose main metabolic products were identified as [2-13C]ethanol, [2-13C]succinate and [1,3-13C2]glycerol. These metabolites were excreted by C. fasciculata into the incubation medium, while in the cells [3-13C]phosphoenolpyruvate was also detected in addition to the aforementioned compounds. The C3 acid is apparently the acceptor of the primary CO2 fixation reaction, which leads in Trypanosomatids to the synthesis of succinate. By addition of sodium bicarbonate to the incubation mixture L-[3-13C]malate was detected among the excretion products, while the ethanol:succinate ratio of 2.0 in the absence of bicarbonate changed to a ratio of 0.6 in the presence of the latter. This was due to a shift of the balance between carboxylation of phosphoenolpyruvate, leading to succinate, and pyruvate decarboxylation leading to ethanol. The addition of 25% 2H2O to the incubation mixture led to the formation of [2-13C, 2-2H]ethanol derived from the prior incorporation of 2H+ into pyruvate in the reactions mediated by either pyruvate kinase or malic enzyme. However, no 2H+ incorporation into L-malate was detected, excluding the possibility that the latter was formed by carboxylation of pyruvate, and lending support to the idea that L-malate results from the carboxylation of phosphoenolpyruvate to oxaloacetate by phosphoenolpyruvate carboxykinase. The formation of [2-13C, 2-2H]-succinate under the same conditions reflected the uptake of 2H+ during the reduction of fumarate. When the incubations were carried out in the presence of 100% 2H2O, several [1-13C, 1-2H]ethanol species were detected, as well as [2-13C, 2-2H]malate and [1,3-13C2, 1,3-2H2]glycerol. The former deuterated compounds reflect the existence of NAD2H species when the incubations were carried out in 100% 2H2O, while the incorporation of 2H+ into [1,3-13C2]glycerol must be attributed to the phosphoglucose-isomerase-mediated reaction during glycolysis.     

Inhibition of the polymerase chain reaction by sputum samples from tuberculosis patients after processing using a silica-guanidiniumthiocyanate DNA isolation procedure.

With the objective to evaluate PCR-mediated detection of Mycobacterium tuberculosis DNA as a diagnostic procedure for diagnosis of tuberculosis in individuals attending ambulatory services in Primary Health Units of the City Tuberculosis Program in Rio de Janeiro, Brazil, their sputum samples were collected and treated with a DNA extraction procedure using silica-guanidiniumthiocyanate. This procedure has been described to be highly efficient for extraction of different kind of nucleic acids from bacteria and clinical samples. Upon comparing PCR results with the number of acid-fast bacilli, no direct relation was observed between the number of bacilli present in the sample and PCR positivity. Part of the processed samples was therefore spiked with pure DNA of M. tuberculosis and inhibition of the PCR reaction was verified in 22 out of 36 (61%) of the samples, demonstrating that the extraction procedure as originally described should not be used for PCR analysis of sputum samples.