Peroxynitrite reactivity with amino acids and proteins

Summary. Peroxynitrite, the product of the fast reaction between nitric oxide (NO) and superoxide O₂ ^– radicals, is an oxidizing and nitrating agent which is able to traverse biological membranes. The reaction of peroxynitrite with proteins occurs through three possible pathways. First, peroxynitrite reacts directly with cysteine, methionine and tryptophan residues. Second, peroxynitrite reacts fast with transition metal centers and selenium-containing amino acids. Third, secondary free radicals arising from peroxynitrite homolysis such as hydroxyl and nitrogen dioxide, and the carbonate radical formed in the presence of carbon dioxide, react with protein moieties too. Nitration of tyrosine residues is being recognized as a marker of the contribution of nitric oxide to oxidative damage. Peroxynitrite-dependent tyrosine nitration is likely to occur through the initial reaction of peroxynitrite with carbon dioxide or metal centers leading to secondary nitrating species. The preferential protein targets of peroxynitrite and the role of proteins in peroxynitrite detoxifying pathways are discussed.     

Histidine and lysine as targets of oxidative modification

Summary. Histidine and lysine are two representative targets of oxidative modifications. Histidine is extremely sensitive to a metal-catalyzed oxidation, generating 2-oxo-histidine and its ring-ruptured products, whereas the oxidation of lysine generates carbonyl products, such as aminoadipic semialdehyde. On the other hand, both histidine and lysine are nucleophilic amino acids and therefore vulnerable to modification by lipid peroxidation-derived electrophiles, such as 2-alkenals, 4-hydroxy-2-alkenals, and ketoaldehydes, derived from lipid peroxidation. Histidine shows specific reactivity toward 2-alkenals and 4-hydroxy-2-alkenals, whereas lysine is a ubiquitous target of aldehydes, generating various types of adducts. Covalent binding of reactive aldehydes to histidine and lysine is associated with the appearance of carbonyl reactivity and antigenecity of proteins.     

Comparison of post-translational modifications of alpha A-crystallin from normal and hereditary cataract rats

Summary. In order to investigate the relationship between lens opacities and the various modifications of lens proteins, we analyzed and compared the properties of lens proteins of 85-day old normal Wistar rats and the hereditary cataract model, ICR/f rats. The present study identified many differences between normal and mutant lens proteins. In the ICR/f mutant rats, the relative amounts of gamma-crystallin decreased and high molecular weight (HMW) protein increased. Racemization and isomerization of Asp-151 of alpha A-crystallin was observed in the mutant ICR/f rats, and Met-1 of alpha A-crystallin was oxidized to methionine sulfoxide. These modifications were not found in the age-matched normal rats. These tendencies are consistent with aged and cataractous human lenses.     

Structure and distribution of floral trichomes in Lycaste and Sudamerlycaste (Orchidaceae: Maxillariinae s.l.)

Phylogenetic analysis indicates that Lycastinae should be incorporated into a more broadly defined Maxillariinae. This is supported by several anatomical features, including the presence of sunken, glandular trichomes in both Lycastinae and Maxillariinae s.s. Until recently, these were known only from vegetative organs, but have since been reported from flowers of Maxillaria dichroma. One character currently used to distinguish between Lycaste and Sudamerlycaste is the distribution of floral trichomes. In this article, we test the reliability of this character, describe the floral micromorphology of Lycaste and Sudamerlycaste and investigate whether their flowers bear sunken hairs. Their floral micromorphology is compared with that of other genera currently assigned to Maxillariinae s.l. Flowers of Lycaste and Sudamerlycaste bear conical or obpyriform papillae and unbranched and unequally branched multicellular trichomes. Contrary to previous reports that trichomes are confined to the column in Sudamerlycaste, they also occur in the tepal axils. Labellar trichomes, although often present in Lycaste, are lacking in Sudamerlycaste. In Lycaste sections Lycaste and Aromaticae, floral trichomes tend to be unbranched, whereas section Intermediae has both unbranched and branched hairs. Branched hairs are more common in Sudamerlycaste. Some hairs are tracheoidal, pitted and lignified. These mainly occur in section Lycaste and, to a degree, in section Intermediae, but are absent from section Aromaticae and most species of Sudamerlycaste. Branched column hairs, present in Sudamerlycaste, are absent from all sections of Lycaste, and tracheoidal column hairs occur only in Sudamerlycaste. Sunken floral hairs are absent from both genera. Trichome structure and distribution may prove useful in distinguishing between these taxa and in elucidating the intergeneric relationships of Maxillariinae s.l.© 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 164 , 409–421.     

Protein tyrosine nitration in hydrophilic and hydrophobic environments

Summary. In this review we address current concepts on the biological occurrence, levels and consequences of protein tyrosine nitration in biological systems. We focused on mechanistic aspects, emphasizing on the free radical mechanisms of protein 3-nitrotyrosine formation and critically analyzed the restrictions for obtaining large tyrosine nitration yields in vivo, mainly due to the presence of strong reducing systems (e.g. glutathione) that can potently inhibit at different levels the nitration process. Evidence is provided to show that the existence of metal-catalyzed processes, the assistance of nitric oxide-dependent nitration steps and the facilitation by hydrophobic environments, provide individually and/or in combination, feasible scenarios for nitration in complex biological milieux. Recent studies using hydrophobic tyrosine analogs and tyrosine-containing peptides have revealed that factors controlling nitration in hydrophobic environments such as biomembranes and lipoproteins can differ to those in aqueous compartments. In particular, exclusion of key soluble reductants from the lipid phase will more easily allow nitration and lipid-derived radicals are suggested as important mediators of the one-electron oxidation of tyrosine to tyrosyl radical in proteins associated to hydrophobic environments. Development and testing of hydrophilic and hydrophobic probes that can compete with endogenous constituents for the nitrating intermediates provide tools to unravel nitration mechanisms in vitro and in vivo; additionally, they could also serve to play cellular and tissue protective functions against the toxic effects of protein tyrosine nitration.     

Taurine restores ethanol-induced depletion of antioxidants and attenuates oxidative stress in rat tissues

Summary. Ethanol by its property of generating free radicals during the course of its metabolism causes damage to cell structure and function. The study investigates the protective effects of the antioxidant aminoacid taurine on ethanol-induced lipid peroxidation and antioxidant status. Male Wistar rats of body weight 170–190g were divided into 4 groups and maintained for 28 days as follows: a control group and taurine-supplemented control group, taurine supplemented and unsupplemented ethanol-fed group. Ethanol was administered to rats at a dosage of 3g/kg body weight twice daily and taurine was provided in the diet (10g/kg diet). Lipid peroxidation products and antioxidant potential were quantitated in plasma and in following tissues liver, brain, kidney and heart.Increased levels of thiobarbituric acid substances (TBARS) and lipid hydroperoxides (LHP) in plasma and tissues, decreased activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) were observed in hemolysate and tissues of ethanol-fed rats. The contents of reduced glutathione (GSH), -tocopherol and ascorbic acid in plasma and tissues were significantly reduced in these animals as compared to control animals. Simultaneous administration of taurine along with ethanol attenuated the lipid peroxidation process and restored the levels of enzymatic and non-enzymatic antioxidants. We propose that taurine may have a bioprotective effect on ethanol-induced oxidative stress.     

Optimal and effective oral dose of taurine to prolong exercise performance in rat

Summary. The aim of this study was to determine the effective and optimum dose of taurine for exercise performance and to maintain tissue taurine concentration. Rats received a respective daily dose of 0, 20, 100, and 500mg/kg body weight of taurine (EC and ET-1, -2, -3 groups, respectively) for two weeks, and then, were subjected to treadmill until exhaustion. The running time to exhaustion was significantly prolonged by 25% and 50% in the ET-2 and -3 groups, respectively, compared to that in the EC group accompanied with maintenance of taurine tissue concentrations. Furthermore, the oxidative glutathione per total glutathione ratio in tissues was inhibited in the ET-2 and -3 groups whereas it was higher in the EC group than in both the no exercise and taurine-administered groups. Therefore the effective and optimal doses of oral taurine administration for two weeks on a transient exercise performance were between 100 and 500mg/kg/day.     

Protein levels of genes encoded on chromosome 21 in fetal Down Syndrome brain (Part V): Overexpression of phosphatidyl-inositol-glycan class P protein (DSCR5)

Summary. Down Syndrome (DS, trisomy 21) is the most common genetic cause of mental retardation. The completed sequencing of genes encoded on chromosome 21 provides excellent basic information, however the molecular mechanisms leading to the phenotype of DS remain to be elucidated. Although overexpression of chromosome 21 encoded genes has been documented information at the protein expression level is mandatory as it is the proteins that carry out function. We therefore decided to evaluated expression level of seven proteins whose genes are encoded on chromosome 21: DSCR4, DSCR5, DSCR6; KIR4.2, GIRK2, KCNE1 and KCNE2 in fetal cortex brain of DS and controls at the early second trimester of pregnancy by Western blotting. -actin and neuron specific enolase (NSE) were used to normalise cell loss and neuronal loss. DSCR5 (PIG-P), a component of glycosylphosphatidylinositol-N-acetylglucosaminyltransferase (GPI-GnT), was overexpressed about twofold, even when levels were normalised with NSE. DSCR6 was overexpressed in addition but when normalised versus NSE, levels were comparable to controls. DSCR4 was not detectable in fetal brain. Potassium channels KIR4.2 and GIRK2 were comparable between DS and controls, whereas KCNE1 and KCNE2 were not detectable. Quantification of these proteins encoded on chromosome 21 revealed that not all gene products of the DS critical region are overexpressed in DS brain early in life, indicating that the DS phenotype cannot be simply explained by the gene dosage effect hypothesis. Overexpression of PIG-P (DSCR5) may lead to or represent impaired glycosylphosphatidylinositol-N-acetylglucosaminyltransferase mediated posttranslational modifications and subsequent anchoring of proteins to the plasma membrane.     

Conjugation of glutathione to oxidized tyrosine residues in peptides and proteins

Tyrosine residues are sensitive to oxidation and can be converted to hydroperoxides either by superoxide reacting with the Tyr radical or by singlet oxygen. These hydroperoxides rearrange to bicyclic derivatives that are readily reduced to more stable hydroxides. The aromatic character of tyrosine is lost, but the product contains an α-β unsaturated carbonyl group and is, therefore, an electrophile. We have generated hydroxide derivatives of several Tyr-containing peptides and shown using liquid chromatography/mass spectrometry that they undergo Michael addition with GSH. For Tyr-Gly, rate constants of 9.2 and 11.8 m(-1)min(-1) were measured for the two chromatographically distinct isomers. Unusual for GSH addition to an electrophile, the reaction is reversible, with a half-life of many hours for the reverse reaction. These kinetics indicate that with a typical cellular concentration of 5 mm GSH, >95% Tyr-Gly hydroxide would become conjugated with a half-life of ～15 min. Sperm whale myoglobin forms a hydroperoxide on Tyr-151 in a hydrogen peroxide/superoxide-dependent reaction. We show that its hydroxide derivative reacts with GSH to form a conjugate. Detection of the conjugate required stabilization by reduction; otherwise, the reverse reaction occurred during tryptic digestion and analysis. Our findings represent a novel mechanism for peptide or protein glutathionylation involving a carbon-sulfur cross-link between oxidized Tyr and Cys. As with other electrophiles, the oxidized Tyr should undergo a similar reaction with Cys residues in proteins to give intramolecular or intermolecular protein cross-links. This mechanism could give rise to protein cross-linking in conditions of oxidative stress.     

Hypochlorite-induced oxidation of amino acids, peptides and proteins

Summary. Activated phagocytes generate the potent oxidant hypochlorite (HOCl) via the release of the enzyme myeloperoxidase and hydrogen peroxide. HOCl is known to react with a number of biological targets including proteins, DNA, lipids and cholesterol. Proteins are likely to be major targets for reaction with HOCl within a cell due to their abundance and high reactivity with HOCl. This review summarizes information on the rate of reaction of HOCl with proteins, the nature of the intermediates formed, the mechanisms involved in protein oxidation and the products of these reactions. The predicted targets for reaction with HOCl from kinetic modeling studies and the consequences of HOCl-induced protein oxidation are also discussed.     

Redox regulation of heat shock protein expression in aging and neurodegenerative disorders associated with oxidative stress: A nutritional approach

Summary. Oxidative stress has been implicated in mechanisms leading to neuronal cell injury in various pathological states of the brain. Alzheimers disease (AD) is a progressive disorder with cognitive and memory decline, speech loss, personality changes and synapse loss. Many approaches have been undertaken to understand AD, but the heterogeneity of the etiologic factors makes it difficult to define the clinically most important factor determining the onset and progression of the disease. However, increasing evidence indicates that factors such as oxidative stress and disturbed protein metabolism and their interaction in a vicious cycle are central to AD pathogenesis.Brains of AD patients undergo many changes, such as disruption of protein synthesis and degradation, classically associated with the heat shock response, which is one form of stress response. Heat shock proteins are proteins serving as molecular chaperones involved in the protection of cells from various forms of stress.Recently, the involvement of the heme oxygenase (HO) pathway in anti-degenerative mechanisms operating in AD has received considerable attention, as it has been demonstrated that the expression of HO is closely related to that of amyloid precursor protein (APP). HO induction occurs together with the induction of other HSPs during various physiopathological conditions. The vasoactive molecule carbon monoxide and the potent antioxidant bilirubin, products of HO-catalyzed reaction, represent a protective system potentially active against brain oxidative injury. Given the broad cytoprotective properties of the heat shock response there is now strong interest in discovering and developing pharmacological agents capable of inducing the heat shock response.Increasing interest has been focused on identifying dietary compounds that can inhibit, retard or reverse the multi-stage pathophysiological events underlying AD pathology. Alzheimers disease, in fact, involves a chronic inflammatory response associated with both brain injury and -amyloid associated pathology. All of the above evidence suggests that stimulation of various repair pathways by mild stress has significant effects on delaying the onset of various age-associated alterations in cells, tissues and organisms. Spice and herbs contain phenolic substances with potent antioxidative and chemopreventive properties, and it is generally assumed that the phenol moiety is responsible for the antioxidant activity. In particular, curcumin, a powerful antioxidant derived from the curry spice turmeric, has emerged as a strong inducer of the heat shock response. In light of this finding, curcumin supplementation has been recently considered as an alternative, nutritional approach to reduce oxidative damage and amyloid pathology associated with AD. Here we review the importance of the heme oxygenase pathway in brain stress tolerance and its significance as an antidegenerative mechanism potentially important in AD pathogenesis. These findings have offered new perspectives in medicine and pharmacology, as molecules inducing this defense mechanism appear to be possible candidates for novel cytoprotective strategies. In particular, manipulation of endogenous cellular defense mechanisms such as the heat shock response, through nutritional antioxidants or pharmacological compounds, represents an innovative approach to therapeutic intervention in diseases causing tissue damage, such as neurodegeneration. Consistent with this notion, maintenance or recovery of the activity of vitagenes, such as the HO gene, conceivably may delay the aging process and decrease the occurrence of age-related neurodegenerative diseases.     

Nitric oxide and cell signaling; modulation of redox tone and protein modification

Summary. Reactive oxygen species (ROS) and reactive nitrogen species (RNS) have an impact on many cellular processes, often serving as signal transducers in both physiological and pathological situations. These small molecules can act as ligands for receptors as is the case for nitric oxide and guanylate cyclase. However, they can also modify proteins, changing their function and establishing a baseline for other signals in a process that we have termed redox tone. In this review, we discuss the different mechanisms of redox cell signaling, and give specific examples of RNS participation in cell signaling via classical and redox tone pathways.     

Analysis of 6-hydroxy-2-aminocaproic acid (HACA) as a specific marker of protein oxidation: The use of <Emphasis Type="Italic">N(O,S)</Emphasis>-ethoxycarbonyl trifluoroethyl ester derivatives and gas chromatography/mass spectrometry

Summary. An alteration of low density lipoprotein (LDL) apolipoprotein (apo) B-100 structure by direct oxidative modification is an important mechanism involved in atherogenesis. There is difficulty in quantifying this type of modification because a lack of specific assays. The use of N(O,S)-ethoxycarbonyl trifluoroethyl amino acid esters for a rapid and sensitive determination of 6-hydroxy-2-aminocaproic acid (HACA), a highly specific marker of metal catalyzed protein oxidation, by using standard gas chromatography/electron impact mass spectrometry, is discussed. The derivatives are formed by the unlabored reaction of amino acids with ethylchloroformate plus trifluoroethanol plus pyridine. Femtomole levels of HACA can be reproducible measured in different LDL preparations subjected to oxidative damage in the presence of iron or copper. HACA determination compares well with the measurement of carbonyl groups that are generally accepted as a nonspecific index of protein oxidation. Thus, the method could prove to be a sensitive assay for studying specific apoB-100 modification.     

Revision of the Euthalia phemius complex (Lepidoptera: Nymphalidae) based on morphology and molecular analyses

Adults of the Euthalia phemius complex, which is composed of three South‐East Asian nymphalid species, Euthalia phemius, Euthalia ipona, and Euthalia euphemia, were genetically analysed by examining mitochondrial and nuclear genes. The E. phemius complex was also examined morphologically, with particular emphasis on wing markings and male genitalia. No significant differences amongst the three species in the complex were detected with respect to either genetic distance or genital morphology. We therefore conclude that the three currently recognized Euthalia species belong to a single species. Accordingly, E. ipona is synonymized with E. phemius. Euthalia euphemia is treated as a subspecies of E. phemius. Type specimens of all taxa and a synonymic list for the E. phemius complex are also given. In addition, we briefly discuss the evolution and biogeography of the species complex. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 164 , 304–327.     

The influence of conserved tyrosine 30 and tissue-dependent differences in sequence on ferritin function: use of blue and purple Fe(III) species as reporters of ferroxidation

Ferritins uniquely direct the vectorial transfer of hydrated Fe(II)/Fe(III) ions to a condensed ferric phase in the central cavity of the soluble protein. Secondary, tertiary and quaternary structure are conserved in ferritin, but only five amino acid residues are conserved among all known ferritins. The sensitivity of ferroxidation rates to small differences in primary sequence between ferritin subunits that are cell-specifically expressed or to the conservative replacement of the conserved tyrosine 30 residue was demonstrated by examining recombinant (frog) H-type (red blood cell predominant) and M-type subunit (liver predominant) proteins which are both fast ferritins; the proteins form two differently colored Fe(III)-protein complexes absorbing at 550?nm or 650?nm, respectively. The complexes are convenient reporters of Fe(III)-protein interaction because they are transient in contrast to the Fe(III)-oxy complexes measured in the past at 310–420?nm, which are stable because of contributions from the mineral itself. The A650-nm species formed 18-fold faster in the M-subunit protein than did the 550-nm species in H-subunit ferritin, even though all the ferroxidase residues are the same; the Vmax was fivefold faster but the Hill coefficents were identical (1.6), suggesting similar mechanisms. In H-subunit ferritin, substitution of phenylalanine for conserved tyrosine 30 (located in the core of the subunit four-helix bundle) slowed ferroxidation tenfold, whereas changing surface tyrosine 25 or tyrosine 28 had no effect. The Fe(III)-tyrosinate was fortunately not changed by the mutation, based on the resonance Raman spectrum, and remained a suitable reporter for Fe(III)-protein interactions. Thus, the A550/650?nm can also report on post-oxidation events such as transport through the protein. The impact of Y30F on rates of formation of Fe(III)-protein complexes in ferritin, combined with Mössbauer spectroscopic studies that showed the parallel formation of multiple Fe(III) postoxidation species (three dinuclear oxy and one trinuclear oxy species) (A. S. Periera et al., Biochemistry 36?:?7917–7927, 1997) and the loss of several of the multimeric Fe(III) post-oxidation species in a Y30F alteration of human recombinant H-ferritin (E. R. Bauminger et al., Biochem J. 296?:?709–719, 1993), indicate that at least one of the pathways for Fe oxidation/transfer in ferritin is through the center of the four-helix bundle and is influenced by structural features dependent on tyrosine 30.     

Modularity in attachment organs of African Cichlidogyrus (Platyhelminthes: Monogenea: Ancyrocephalidae) reflects phylogeny rather than host specificity or geographic distribution

Cichlidogyrus spp. (Monogenea, Ancyrocephalidae) are common parasites of cichlid fishes from Africa and the Levant. They display important morphological variation in their attachment apparatus and infect a broad host spectrum throughout a wide geographic range. Thus, they offer an interesting model to investigate to what extent the phenotypic variability of the attachment organ among congeners is related to host specificity, geographic/environmental components, or phylogeny. A geometric morphometric approach was carried out to analyse the shape variation of sclerotized structures of the attachment organ within 66 African species of the genus Cichlidogyrus. The interspecific shape comparison supports the presence of three main morphological configurations, each consisting of a given combination of particular sclerite shapes. Moreover, data emphasize strong coordination and integration (shape co‐variation) among the different sclerites jointly forming the attachment organ. Although attachment apparatuses are usually considered to be the result of adaptive processes and must be adapted to the hosts and local environmental conditions, we found no relationship between these clusters and host specificity or geographical distribution. Nevertheless, groups are partially congruent with those obtained with the molecular phylogeny of a subset of species, suggesting a phylogenetic constraint rather than an adaptation to either hosts or environment. Because of the necessity to form a functional entity, modularity within attachment organ imposes important evolutionary constraint. This provides new insights into the evolvability of attachment organs, as well as into the morphological basis of host specificity and host–parasite co‐evolutionary interaction in helminth parasites. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 694–706.     

Gender-related differences in carnosine,anserine and lysine content of murine skeletal muscle

Summary. The aminoacyl-imidazole dipeptides carnosine (-alanyl-L-histidine) and anserine (-alanyl-1-methyl-histidine) are present in relatively high concentrations in excitable tissues, such as muscle and nervous tissue. In the present study we describe the existence of a marked sexual dimorphism of carnosine and anserine in skeletal muscles of CD1 mice. In adult animals the concentrations of anserine were higher than those of carnosine in all skeletal muscles studied, and the content of aminoacyl-imidazole dipeptides was remarkably higher in males than in females. Postnatal ontogenic studies and hormonal manipulations indicated that carnosine synthesis was up-regulated by testosterone whereas anserine synthesis increased with age. Regional variations in the concentrations of the dipeptides were observed in both sexes, skeletal muscles from hind legs having higher amounts of carnosine and anserine than those present in fore legs or in the pectoral region. The concentration of L-lysine in skeletal muscles also showed regional variations and a sexual dimorphic pattern with females having higher levels than males in all muscles studied. The results suggest that these differences may be related with the anabolic action of androgens on skeletal muscle.     

Phylogenetics and biogeography of the Balkan ‘sand gobies’ (Teleostei: Gobiidae): vulnerable species in need of taxonomic revision

Within the Atlantic–Mediterranean region, the ‘sand gobies’ are abundant and widespread, and play an important role in marine, brackish, and freshwater ecosystems. They include the smallest European freshwater fish, Economidichthys trichonis, which is threatened by habitat loss and pollution, as are several other sand gobies. Key to good conservation management is an accurate account of the number of evolutionary significant units. Nevertheless, many taxonomic and evolutionary questions remain unresolved within the clade, and molecular studies are lacking, especially in the Balkans. Using partial 12S and 16S mitochondrial ribosomal DNA sequences of 96 specimens of at least eight nominal species (both freshwater and marine populations), we assess species relationships and compare molecular and morphological data. The results obtained do not support the monophyly of Economidichthys, suggesting the perianal organ to be a shared adaptation to hole‐brooding rather than a synapomorphy, and urge for a taxonomic revision of Knipowitschia. The recently described Knipowitschia montenegrina seems to belong to a separate South‐East Adriatic lineage. Knipowitschia milleri, an alleged endemic of the Acheron River, and Knipowitschia cf. panizzae, are shown to be very closely related to other western Greek Knipowitschia populations, and appear conspecific. A distinct Macedonian–Thessalian lineage is formed by Knipowitschia thessala, whereas Knipowitschia caucasica appears as an eastern lineage, with populations in Thrace and the Aegean. The present study combines the phylogeny of a goby radiation with insights on the historical biogeography of the eastern Mediterranean, and identifies evolutionary units meriting conservation attention. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105 , 73–91.     

Modulation of ventral pallidal dopamine and glutamate release by the intravenous anesthetic propofol studied by in vivo microdialysis

Summary. The intravenous anesthetic propofol is reported to have various psychological side effects as hallucinations, sexual disinhibition, or euphoria. Hedonic and rewarding states like these are modulated by the dopaminergic system in the nucleus accumbens, prefrontal cortex and also in the ventral pallidum and by the glutamatergic system in the neocortex and limbic system. In the present study, propofol was administered either alone or in combination with the GABAA receptor antagonist bicuculline via reverse microdialysis into the ventral pallidum of freely moving rats. Dialysis fractions were taken every 20min and analyzed for dopamine and glutamate using high performance liquid chromatography. Application of propofol decreased dopamine levels in the ventral pallidum. This effect seems to be mainly mediated through GABAA receptors, since it was compensated by the GABAA receptor antagonist bicuculline. Propofol and propofol plus bicuculline exerted no effect on glutamate release in this brain region. The reduced dopamine release in ventral pallidum was most probably mediated through a GABAergic feedback loop from the ventral pallidum via the nucleus accumbens to the dopaminergic neurons of the ventral tegmental area or by long loop feedback. As an increase but not a decrease of dopamine release in the ventral pallidum is involved in hedonic and rewarding properties, similar symptoms induced by propofol seem to be unrelated to an action of propofol in the ventral pallidum.     

Patterns of diversification in two species of short‐tailed bats (Carollia Gray, 1838): the effects of historical fragmentation of Brazilian rainforests

The small‐sized frugivorous bat Carollia perspicillata is an understory specialist and occurs in a wide range of lowland habitats, tending to be more common in tropical dry or moist forests of South and Central America. Its sister species, Carollia brevicauda, occurs almost exclusively in the Amazon rainforest. A recent phylogeographic study proposed a hypothesis of origin and subsequent diversification for C. perspicillata along the Atlantic coastal forest of Brazil. Additionally, it also found two allopatric clades for C. brevicauda separated by the Amazon Basin. We used cytochrome b gene sequences and a more extensive sampling to test hypotheses related to the origin and diversification of C. perspicillata plus C. brevicauda clade in South America. The results obtained indicate that there are two sympatric evolutionary lineages within each species. In C. perspicillata, one lineage is limited to the Southern Atlantic Forest, whereas the other is widely distributed. Coalescent analysis points to a simultaneous origin for C. perspicillata and C. brevicauda, although no place for the diversification of each species can be firmly suggested. The phylogeographic pattern shown by C. perspicillata is also congruent with the Pleistocene refugia hypothesis as a likely vicariant phenomenon shaping the present distribution of its intraspecific lineages. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 527–539.