Stimulation of group I mGlu receptors in the ventrotegmental area enhances extracellular dopamine in the rat medial prefrontal cortex

Group I mGlu receptors have been implicated in the control of brain dopamine release. However, the receptor subtype involved and the precise site of action have not been determined. In this study we show that (R,S)3,5-dihydroxyphenylglycine (DHPG; 6 and 60 nmol ICV), a selective group I mGlu receptor agonist, raised extracellular dopamine respectively by 176% and 243% of basal values in the medial prefrontal cortex as assessed by in vivo microdialysis in conscious rats. (R,S)2-chloro-5-hydroxyphenylglycine (60 nmol ICV), a selective mGlu5 receptor agonist, raised extracellular dopamine by 396% of basal values. Intra-VTA DHPG (0.6–6 nmol) mimicked ICV injection whereas intracortical infusion (1–1000 µmol/L) had no effect. DHPG-induced rise of extracellular dopamine was reversed by tetrodotoxin and by the selective mGlu1 and mGlu5 receptor antagonists 7(hydroxyimino)cyclopropa[b]chromen-1a-carboxylate (CPCCOEt) and 2-methyl-6-(phenylethynyl)pyridine (MPEP) either ICV or into the ventrotegmental area (VTA), suggesting that neuronal release and both mGlu1 and mGlu5 receptors were involved. These results support the existence of functional mGlu1 and mGlu5 receptors in the VTA regulating the release of dopamine in the medial prefrontal cortex.     

Fluoxetine Increases Extracellular Dopamine in the Prefrontal Cortex by a Mechanism Not Dependent on Serotonin

Fluoxetine at 10 and 25 mg/kg increased (167 and 205%, respectively) the extracellular dopamine concentration in the prefrontal cortex, whereas 25 (but not 10) mg/kg citalopram raised (216%) dialysate dopamine. No compound modified dialysate dopamine in the nucleus accumbens. The effect of 25 mg/kg of both compounds on cortical extracellular dopamine was not significantly affected by 300 mg/kg p-chlorophenylalanine (PCPA) (fluoxetine, saline, 235%; PCPA, 230%; citalopram, saline, 179%; PCPA, 181%). PCPA depleted tissue and dialysate serotonin by approximately 90 and 50%, respectively, and prevented the effect of fluoxetine and citalopram on dialysate serotonin (fluoxetine, saline, 246%; PCPA, 110%; citalopram, saline, 155%; PCPA, 96%). Citalopram significantly raised extracellular serotonin from 0.1 to 100 microM (251-520%), whereas only 10 and 100 microM increased dialysate dopamine (143-231%). Fluoxetine similarly increased extracellular serotonin (98-336%) and dopamine (117-318%). PCPA significantly reduced basal serotonin and the effects of 100 microM fluoxetine (saline, 272%; PCPA, 203%) and citalopram (saline, 345%; PCPA, 258%) on dialysate serotonin but did not modify their effect on dopamine (fluoxetine, saline, 220%; PCPA, 202%; citalopram, saline, 191%; PCPA, 211%). The results clearly show that the effects of fluoxetine and of high concentrations of citalopram on extracellular dopamine do not depend on their effects on serotonin.     

Intracolonial genetic variability in honeybee larval resistance to the chalkbrood and American foulbrood parasites

The origin of multiple mating of queens in social Hymenoptera is a widely debated topic in evolutionary biology. One of the hypotheses is that genetic variability would benefit the colony by increasing its resistance to parasites through various mechanisms. One among the predictions of this hypothesis is that the resistance of different patrilines within a colony to parasites of different species should be independent, as a result of independent gene-for-gene interactions with each parasite. To test this aspect of the hypothesis, two honeybee colonies (Apis mellifera) were infected with the fungus Ascosphaera apis and two colonies with both A. apis and the American foulbrood bacterium Paenibacillus larvae. Patrilines were found to vary in resistance of larvae to A. apis in all four colonies, but similar variation in resistance was not found to P. larvae. Common resistance to both pathogens was not detected. This study supports the hypothesis that polyandry in social insects could have originated as an adaptation to decrease the impact of diseases.     

Rampant horizontal transfer and duplication of rubisco genes in eubacteria and plastids

Previous work has shown that molecular phylogenies of plastids, cyanobacteria, and proteobacteria based on the rubisco (ribulose-1,5- bisphosphate carboxylase/oxygenase) genes rbcL and rbcS are incongruent with molecular phylogenies based on other genes and are also incompatible with structural and biochemical information. Although it has been much speculated that this is the consequence of a single horizontal gene transfer (of a proteobacterial or mitochondrial rubisco operon into plastids of rhodophytic and chromophytic algae), neither this hypothesis nor the alternative hypothesis of ancient gene duplication have been examined in detail. We have conducted phylogenetic analyses of all available bacterial rbcL sequences, and representative plastid sequences, in order to explore these alternative hypothesis and fully examine the complexity of rubisco gene evolution. The rbcL phylogeny reveals a surprising number of gene relationships that are fundamentally incongruent with organismal relationships as inferred from multiple lines of other molecular evidence. On the order of six horizontal gene transfers are implied by the form I (L8S8) rbcL phylogeny, two between cyanobacteria and proteobacteria, one between proteobacteria and plastids, and three within proteobacteria. Alternatively, a single ancient duplication of the form I rubisco operon, followed by repeated and pervasive differential loss of one operon or the other, would account for much of this incongruity. In all probability, the rubisco operon has undergone multiple events of both horizontal gene transfer and gene duplication in different lineages.      

Development and application of the active surveillance of pathogens microarray to monitor bacterial gene flux

Background  

Human and animal health is constantly under threat by emerging pathogens that have recently acquired genetic determinants that enhance their survival, transmissibility and virulence. We describe the construction and development of an Active Surveillance of Pathogens (ASP) oligonucleotide microarray, designed to 'actively survey' the genome of a given bacterial pathogen for virulence-associated genes.     

Effects of protected fish oil in the diet of periparturient dairy goats on phenotypic variation in blood and milk leukocytes

The goal of this study was to evaluate the effects of dietary protected fish oil (FO) on phenotypic variation in blood, milk leukocytes, and some productive and metabolic parameters in periparturient dairy goats. About 12 Alpine goats, selected from a larger group of second-parity animals, were fed from 15 days before kidding until the 15th day of lactation with the same basal diet that had been supplemented with either 47 g/head per day of FO or 47 g/head per day hydrogenated palm oil (PO). Dry matter intake, live body weight (LBW), body condition score (BCS), and productive performance were evaluated in 2 weeks after kidding. On days 15, 7, and 2 before kidding and days 2, 7, and 15 after kidding, plasma samples were collected for evaluation of alanine aminotransferase, aspartate aminotransferase, non-esterified fatty acids, glucose, beta-hydroxybutyrate, cholesterol, and urea levels. White blood cell and blood leukocyte subsets were counted in whole blood samples on the kidding day, as well as at 1, 4, and 15 days after kidding. In addition, milk somatic cell count, intramammary infection (IMI), and milk leukocyte subsets were evaluated on days 4 and 15 after kidding. No differences were observed in dry matter intake and BCS, while LBW was higher in FO-fed animals. Milk production and composition, plasma metabolites, and liver enzymes were similar in both experimental groups. Blood CD4 positive cells increased constantly (P = 0.05) in FO-fed group, while CD8 and CD14 cell counts significantly increased 4 days after kidding (P < 0.01). Milk leukocyte subsets showed a significant (P < 0.01) decrease in PO-fed group and a non-significant increase (P = 0.34) in FO-fed group, despite the presence of coagulase negative staphylococci IMI. The results of the productive performance evaluation agreed with those of many other studies, which did not find any significant differences between dairy goats fed diets enriched with FO or PO supplements. The administration of FO to dairy goats in transition appeared to affect the variation in blood leukocytes with a constant increase in CD4- and CD8-positive cells in comparison with a PO fat-supplemented diet.     

Thermal plasticity in Drosophila melanogaster : A comparison of geographic populations

Background  

Populations of Drosophila melanogaster show differences in many morphometrical traits according to their geographic origin. Despite the widespread occurrence of these differences in more than one Drosophila species, the actual selective mechanisms controlling the genetic basis of such variation are not fully understood. Thermal selection is considered to be the most likely cause explaining these differences.     

Exome Sequence Reveals Mutations in CoA Synthase as a Cause of Neurodegeneration with Brain Iron Accumulation

Neurodegeneration with brain iron accumulation (NBIA) comprises a clinically and genetically heterogeneous group of disorders with progressive extrapyramidal signs and neurological deterioration, characterized by iron accumulation in the basal ganglia. Exome sequencing revealed the presence of recessive missense mutations in COASY, encoding coenzyme A (CoA) synthase in one NBIA-affected subject. A second unrelated individual carrying mutations in COASY was identified by Sanger sequence analysis. CoA synthase is a bifunctional enzyme catalyzing the final steps of CoA biosynthesis by coupling phosphopantetheine with ATP to form dephospho-CoA and its subsequent phosphorylation to generate CoA. We demonstrate alterations in RNA and protein expression levels of CoA synthase, as well as CoA amount, in fibroblasts derived from the two clinical cases and in yeast. This is the second inborn error of coenzyme A biosynthesis to be implicated in NBIA.