The effect of dexamethasone treatment on the expression of the regulatory genes of ketogenesis in intestine and liver of suckling rats

The influence of the injection of dexamethasone on ketogenesis in 12 day old suckling rats was studied in intestine and liver by determining mRNA levels and enzyme activity of the two genes responsible for regulation of ketogenesis: carnitine palmitoyl transferase I (CPT 1) and mitochondrial HMG-CoA synthase. Dexamethasone produced a 2 fold increase in mRNA and activity of CPT I in intestine, but led to a decrease in mitt HMG-CoA synthase. In liver the mRNA levels and activity of both CPT I and mitt HMG-CoA synthase decreased. Comparison of these values with the ketogenic rate of both tissues following dexamethasone treatment suggests that mitt HMG-CoA synthase could be the main gene responsible for the regulation of ketogenesis in suckling rats. The changes produced in serum ketone bodies by dexamethasone, with a profile that is more similar to the ketogenic rate in the liver than that in the intestine, indicate that liver contributes more to ketone body synthesis in suckling rats. Two day treatment with dexamethasone produced no change in mRNA or activity levels for CPT I in liver or intestine. While mRNA levels for mitt HMG-CoA synthase changed little, the enzyme activity is decreased in both tissues.     

Aerobic chromate reduction by Bacillus subtilis

We have studied the reduction of hexavalent chromium (chromate) to the less toxic trivalent form by using cell suspensions and cell-free extracts from the common soil bacterium, Bacillus subtilis. B. subtilis was able to grow and reduce chromate at concentrations ranging from 0.1 to 1 mM K₂CrO₄. Chromate reduction was not affected by a 20-fold excess of nitrate-compound that serves as alternate electron acceptor and antagonizes chromate reduction by anaerobic bacteria. Metabolic poisons including sodium azide and sodium cyanide inhibited chromate reduction. Reduction was effected by a constitutive system associated with the soluble protein fraction and not with the membrane fraction. The reducing activity was heat labile and showed a K_m of 188 m CrO₄ ^2-. The reductase can mediate the transfer of electrons from NAD(P)H to chromate. The results suggest that chromate is reduced via a detoxification system rather than dissimilatory electron transport.     

Lymphocytes apoptosis: young versus aged and humans versus rats

This paper deals with a comparative study of lymphocyte apoptosis in young versus aged and humans versus rats. Apoptotic rate achieved by the use of different apoptogenic inducers, acting at different cellular levels, and cell surface modifications were analyzed. The results showed that aged human lymphocytes and freshly isolated rat lymphocytes were more prone to undergo apoptosis. Therefore, the same apoptotic signal is recognized by human and rat lymphocytes, but the extent of the answer is related to the species, to the intensity of the apoptotic stimulus and to the metabolic/developmental condition of the cells. Surface modifications (lipids and glycans), typical of apoptosis, were observed. Our data showed that cell surface changes are species and age dependent. They are early events, progressively achieved in the course of the apoptotic process involving lateral membrane movements of molecules.     

Testosterone Plus Low-Intensity Physical Training in Late Life Improves Functional Performance,Skeletal Muscle Mitochondrial Biogenesis,and Mitochondrial Quality Control in Male Mice

Testosterone supplementation increases muscle mass in older men but has not been shown to consistently improve physical function and activity. It has been hypothesized that physical exercise is required to induce the adaptations necessary for translation of testosterone-induced muscle mass gain into functional improvements. However, the effects of testosterone plus low intensity physical exercise training (T/PT) on functional performance and bioenergetics are unknown. In this pilot study, we tested the hypothesis that combined administration of T/PT would improve functional performance and bioenergetics in male mice late in life more than low-intensity physical training alone. 28-month old male mice were randomized to receive T/PT or vehicle plus physical training (V/PT) for 2 months. Compare to V/PT control, administration of T/PT was associated with improvements in muscle mass, grip strength, spontaneous physical movements, and respiratory activity. These changes were correlated with increased mitochondrial DNA copy number and expression of markers for mitochondrial biogenesis. Mice receiving T/PT also displayed increased expression of key elements for mitochondrial quality control, including markers for mitochondrial fission-and-fusion and mitophagy. Concurrently, mice receiving T/PT also displayed increased expression of markers for reduced tissue oxidative damage and improved muscle quality. Conclusion: Testosterone administered with low-intensity physical training improves grip strength, spontaneous movements, and respiratory activity. These functional improvements were associated with increased muscle mitochondrial biogenesis and improved mitochondrial quality control.     

Chromatographic behaviour of the molecular forms of guinea-pig skeletal muscle cytoplasmic malate dehydrogenase

The isolated molecular forms of guinea-pig skeletal muscle cytoplasmic malate dehydrogenase have a different chromatographic behaviour through affinity or hydrophobic interaction gels; in all cases the retention of the B form is more noticeable. Chromatography of a partly purified preparation through 5' AMP-Sepharose allows both molecular forms of malate dehydrogenase to be separated and obtained free from lactate dehydrogenase.     

Viscosity decrease of pectin and fruit juices catalyzed by pectin lyase from Penicillium italicum in batch and continuous-flow membrane reactors

Summary The extracellular pectin lyase (PNL, E.C. 4.2.2.10) from Penicillium italicum was utilized in batch and confined in a continuous-flow ultrafiltration membrane reactor. The enzyme catalyzed the decrease in viscosity of pectin solutions at pH 6.0 as well as of different fruit juices at their respective pH. PNL decreased the viscosity of pectin solutions in the membrane (60% after 30 min) more than in the batch (46% after 70 min) reactors, but similar viscosity reduction of fruit juices was achieved in both reactors. The enzyme decreased the viscosity of grape, peach and melon juices to different extents, but failed to do so with apple or pear juices. It can be concluded that the utilization of PNL in a membrane reactor appears of interest for the clarification of fruit juices.     

Behavioral reproductive isolation among sympatric strains of Brachionus plicatilis Müller 1786: insights into the status of this taxonomic species

We present results on cross-mating experiments using Brachionus plicatilis strains collected in three ponds of a coastal marsh (Torreblanca Marsh, Castellón, Spain). These strains were known to differ widely both in morphology and allozyme patterns from a previous study, where they were grouped into three genetically different clonal groups. Although some of the strains co-occurred in the same pond and sexual periods overlapped, no gene flow was found among them. Our first objective was to determine whether behavioral reproductive isolation was responsible for the absence of interbreeding. A second objective was to explore the relationship between sexual isolation and genetic divergence. We performed two experiments. In Experiment 1, we tested five strains from different clonal groups; in Experiment 2, we added a strain from a congeneric species, and strains from different ponds. We recorded male mating behavior in all possible male-female strain pairings. Our data show that males of a strain tend to mate with females of the same strain or genetically similar strains, regardless of the pond they come from. We also found a high positive correlation between isolation distance and genetic distance. These results support the view that mating behavior acts as an important isolating barrier giving cohesion to clonal groups, and structuring populations of this rotifer, and that Brachionus plicatilis is a taxon composed of more than one biological species.     

Functional studies of MP62 during male chromatin decondensation in sea urchins

In amphibians, sperm histone transition post‐fertilization during male pronucleus formation is commanded by histone chaperone Nucleoplasmin (NPM). Here, we report the first studies to analyze the participation of a Nucleoplasmin‐like protein on male chromatin remodeling in sea urchins. In this report, we present the molecular characterization of a nucleoplasmin‐like protein that is present in non fertilized eggs and early zygotes in sea urchin specie Tetrapygus niger. This protein, named MP62 can interact with sperm histones in vitro. By male chromatin decondensation assays and immunodepletion experiments in vitro, we have demonstrated that this protein is responsible for sperm nucleosome disorganization. Furthermore, as amphibian nucleoplasmin MP62 is phosphorylated in vivo immediately post‐fertilization and this phosphorylation is dependent on CDK‐cyclin activities found after fertilization. As we shown, olomoucine and roscovitine inhibits male nucleosome decondensation, sperm histone replacement in vitro and MP62 phosphorylation in vivo. This is the first report of a nucleoplasmin‐like activity in sea urchins participating during male pronucleus formation post‐fecundation. J. Cell. Biochem. 114: 1779–1788, 2013. © 2013 Wiley Periodicals, Inc.