Regulation of α-Transducin and α-Gustducin Expression by a High Protein Diet in the Pig Gastrointestinal Tract

BackgroundThe expression of taste receptors (TASRs) and their signalling molecules in the gastrointestinal (GI) epithelial cells, including enteroendocrine cells (EECs), suggests they participate in chemosensing mechanisms influencing GI physiology via the release of endocrine messengers. TASRs mediate gustatory signalling by interacting with different transducers, including α-gustducin (G_αgust) and α-transducin (G_αtran) G protein subunits. This study tested whether G_αtran and G_αgust immunoreactive (-IR) cells are affected by a short-term (3 days) and long-term (30 days) high protein (Hp) diet in the pig GI tract.ResultIn the stomach, G_αgust and G_αtran-IR cells contained serotonin (5-HT) and ghrelin (GHR), while in the small and large intestine, G_αgust and G_αtran-IR colocalized with 5-HT-, cholecystokinin (CCK)- and peptide YY (PYY)-IR. There was a significant increase in the density of G_αtran-IR cells in the pyloric mucosa in both short- and long-term Hp diet groups (Hp3 and Hp30) vs. the control group (Ctr) (P<0.05), while the increase of G_αgust-IR cells in the pyloric mucosa was significant in Hp30 group vs. Ctr and vs. Hp3 (P<0.05); these cells included G_αtran / 5HT-IR and G_αtran / GHR-IR cells (P<0.05 and P<0.001 vs. Ctr, respectively) as well as G_αgust /5-HT-IR or G_αgust / GHR-IR cells (P<0.05 and P<0.01 vs. Ctr, respectively). In the small intestine, we recorded a significant increase in G_αtran-IR cells in the duodenal crypts and a significant increase of G_αgust-IR cells in the jejunal crypts in Hp3 group compared to HP30 (P<0.05). With regard to the number of G_αtran-G_αgust IR cells colocalized with CCK or 5-HT, there was only a significant increase of G_αtran / CCK-IR cells in Hp3 group compared to Ctr (P = 0.01).ConclusionThis study showed an upregulation of selected subpopulations of G_αgust / G_αtran-IR cells in distinct regions of the pig GI tract by short- and long-term Hp diet lending support to TASR-mediated effects in metabolic homeostasis and satiety mechanisms.     

Tuber borchii fruit body: 2-dimensional profile and protein identification

The formation of the fruit body represents the final phase of the ectomycorrhizal fungus T. borchii life cycle. Very little is known concerning the molecular and biochemical processes involved in the fructification phase. 2-DE maps of unripe and ripe ascocarps revealed different protein expression levels and the comparison of the electropherograms led to the identification of specific proteins for each developmental phase. Associating micropreparative 2-DE to microchemical approaches, such as N-terminal sequencing and 2-D gel-electrophoresis mass-spectrometry, proteins playing pivotal roles in truffle physiology were identified.     

Carbohydrate and amino acid metabolism in Tuber borchii mycelium during glucose utilization: a (13)C NMR study

The metabolism of [1-13C]glucose in the vegetative mycelium of the ectomycorrhizal ascomycete Tuber borchii was studied in order to characterize the biochemical pathways for the assimilation of glucose and amino acid biosynthesis. The pathways were characterized using nuclear magnetic resonance spectroscopy in conjunction with [1-13C]glucose labeling. The enzymes of mannitol cycle and ammonium assimilation were also evaluated. The majority of the 13C label was incorporated into mannitol and this polyol was formed via a direct route from absorbed glucose. Amino acid biosynthesis was also an important sink of assimilated carbon and 13C was mainly incorporated into alanine and glutamate. From this intramolecular 13C enrichment, it is concluded that pyruvate, arising from [1-13C]glucose catabolism, was used by alanine aminotransferase, pyruvate dehydrogenase and pyruvate carboxylase before entering the Krebs cycle. The transfer of 13C-labeled mycelium on [12C]glucose showed that mannitol, alanine, and glutamate carbon were used to synthesize glutamine and arginine that likely play a storage role.     

Novel and simple high-performance liquid chromatographic method for determination of 3-hydroxy-3-methylglutaryl-coenzyme A reductase activity

We present here a high-performance liquid chromatographic method for the evaluation of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase activity. The automated method was applied to fungal and mouse liver extracts and validated by the addition of mevastatin to the reaction mixture and by several intra- and inter-day assays. This method offers important advantages over those previously reported because no radiolabeled substrates or expensive techniques such as mass spectrometry are required, and the time of analysis is relatively short. Moreover, the method can be successfully applied to different biological samples; hence, it should be very useful in evaluating potential inhibitors of the HMG-CoA enzyme and investigating cholesterol metabolism, cell growth and differentiation processes.     

Bacteria-produced ferric exopolysaccharide nanoparticles as iron delivery system for truffles (Tuber borchii)

Applied Microbiology and Biotechnology - Iron exopolysaccharide nanoparticles were biogenerated during ferric citrate fermentation by Klebsiella oxytoca DSM 29614. Before investigating their...     

Pig oocyte vitrification by cryotop method: effects on viability, spindle and chromosome configuration and in vitro fertilization

Three experiments were designed to evaluate the effects of vitrification using Cryotop method on MII porcine oocyte viability, chromosomes configuration, meiotic spindle morphology and in vitro fertilization; to do this, in vitro matured oocytes were subjected to the cryoprotectant treatment excluding the plunging into liquid nitrogen, the whole vitrification/warming/rehydration procedure or no treatment (control). In experiment 1 viable oocytes were not reduced by either cryoprotectants or vitrification when they were evaluated immediately after warming and cryoprotectant dilution. However, after a 2 h incubation, the survival rate significantly decreased (P<0.05). In experiment 2 cryoprotectant exposure significantly (P<0.05) influenced spindle morphology even if chromosome organization did not vary, while vitrification significantly (P<0.05) increased oocytes with damaged spindles and chromosomes displaced from the metaphase plate. No significant improvements in these parameters were observed after 2 h of incubation but, on the contrary, the rate of oocytes with normal chromosome configuration was reduced. In experiment 3 significant differences among the three groups in the fertilization rate but not in the percentages of monospermy fertilization were recorded; in addition, exposure to cryoprotectants and vitrification significantly (P<0.05) increased degenerated oocyte rate. Overall, these findings confirm that porcine oocytes at MII stage are very sensitive to vitrification, which reduces the rate of viable oocytes and alters microtubule organization, thus impairing fertilization; in addition, incubation of oocytes for 2 h after devitrification seems to be detrimental rather than ameliorative. Further improvements of the current protocol will be necessary in order to optimize the Cryotop method for vitrifying pig matured oocytes.