Locomotor Behavior and Memory Dysfunction Induced by 3-Nitropropionic Acid in Adult Zebrafish: Modulation of Dopaminergic Signaling

Huntington's disease (HD) is a progressive neurodegenerative disease characterized by neuropsychiatric disturbance, cognitive impairment, and locomotor dysfunction. In the early stage (chorea) of HD, expression of dopamine D2 receptors (D2R) is reduced, whereas dopamine (DA) levels are increased. Contrary, in the late stage (bradykinesia), DA levels and the expression of D2R and dopamine D1 receptors (D1R) are reduced. 3-Nitropropionic acid (3-NPA) is a toxin that may replicate HD behavioral phenotypes and biochemical aspects. This study assessed the neurotransmitter levels, dopamine receptor gene expression, and the effect of acute exposure to quinpirole (D2R agonist) and eticlopride (D2R antagonist) in an HD model induced by 3-NPA in adult zebrafish. Quinpirole and eticlopride were acutely applied by i.p. injection in adult zebrafish after chronic treatment of 3-NPA (60 mg/kg). 3-NPA treatment caused a reduction in DA, glutamate, and serotonin levels. Quinpirole reversed the bradykinesia and memory loss induced by 3-NPA. Together, these data showed that 3-NPA acts on the dopaminergic system and causes biochemical alterations similar to late-stage HD. These data reinforce the hypothesis that DA levels are linked with locomotor and memory deficits. Thus, these findings may suggest that the use of DA agonists could be a pharmacological strategy to improve the bradykinesia and memory deficits in the late-stage HD.

Micro- and nanoplastic toxicity: A review on size, type, source, and test-organism implications

Polymeric wastes are among the current major environmental problems due to potential pollution and contamination. Within the spectrum of polymeric waste, microplastics (MPs) and nanoplastics (NPs) have gained ground in recent research since these particles can affect the local biota, inducing toxic effects on several organisms. Different outcomes have been reported depending on particle sizes, shape, types, and exposed organisms and conditions, among other variables. This review aimed to compile and discuss the current knowledge and possible literature gaps regarding the MPs and NPs generation and their toxicological effects as stressors, considering polymer type (as polyethylene, polypropylene, polyethylene terephthalate, polystyrene, polyvinyl chloride, or others), size (micro- or nano-scale), source (commercial, lab-synthesized, or environmental) and test organism group. In that sense, 615 publications were analyzed, among which 72 % discussed micro-sized plastics, while <28 % assayed the toxicity of NPs (<1 μm). For most polymers, MPs and NPs were commercially purchased and used without additional size reduction processes; except for polyethylene terephthalate studies that mostly used grinding and cutting methods to obtain MPs. Polystyrene (PS) was the main polymer studied, as both MPs and NPs. PS accounts for >90 % of NPs reports evaluated, reflecting a major literature gap if compared to its 35.3 % share on MPs studies. Among the main organisms, arthropods and fish combined accounted for nearly 40 % of toxicity testing. Overall, the different types of plastics showed a tendency to report toxic effects, except for the 'Survival/lethality' category, which might indicate that polymeric particles induce mostly sublethal toxic effects. Furthermore, despite differences in publication numbers, we observed greater toxicity reported for NPs than MPs with oxidative stress among the majorly investigated endpoints. This study allowed a hazard profile overview of micro/nanoplastics (MNPs) and the visualization of literature gaps, under a broad diversity of toxicological evidence.

Modulation of adenosine signaling reverses 3-nitropropionic acid-induced bradykinesia and memory impairment in adult zebrafish

Huntington's disease (HD) is a neurodegenerative disorder, characterized by motor dysfunction, psychiatric disturbance, and cognitive decline. In the early stage of HD, occurs a decrease in dopamine D₂ receptors and adenosine A_2A receptors (A_2AR), while in the late stage also occurs a decrease in dopamine D₁ receptors and adenosine A₁ receptors (A₁R). Adenosine exhibits neuromodulatory and neuroprotective effects in the brain and is involved in motor control and memory function. 3-Nitropropionic acid (3-NPA), a toxin derived from plants and fungi, may reproduce HD behavioral phenotypes and biochemical characteristics. This study investigated the effects of acute exposure to CPA (A₁R agonist), CGS 21680 (A_2AR agonist), caffeine (non-selective of A₁R and A_2AR antagonist), ZM 241385 (A_2AR antagonist), DPCPX (A₁R antagonist), dipyridamole (inhibitor of nucleoside transporters) and EHNA (inhibitor of adenosine deaminase) in an HD pharmacological model induced by 3-NPA in adult zebrafish. CPA, CGS 21680, caffeine, ZM 241385, DPCPX, dipyridamole, and EHNA were acutely administered via i.p. in zebrafish after 3-NPA (at dose 60 mg/kg) chronic treatment. Caffeine and ZM 241385 reversed the bradykinesia induced by 3-NPA, while CGS 21680 potentiated the bradykinesia caused by 3-NPA. Moreover, CPA, caffeine, ZM 241385, DPCPX, dipyridamole, and EHNA reversed the 3-NPA-induced memory impairment. Together, these data support the hypothesis that A_2AR antagonists have an essential role in modulating locomotor function, whereas the activation of A₁R and blockade of A_2AR and A₁R and modulation of adenosine levels may reduce the memory impairment, which could be a potential pharmacological strategy against late-stage symptoms HD.

Pyriproxyfen Exposure Impairs Cognitive Parameters and Alters Cortisol Levels in Zebrafish

Pyriproxyfen is one of the most used larvicides and insecticides; it acts as an analog of juvenile insect hormone (a growth regulator). It is highly toxic during all stages of mosquito development, suppresses metamorphosis, and interferes in insect reproduction and proliferation. Pyriproxyfen and its main metabolite have been shown to affect brain development in rodents. This compound is employed mainly to eliminate outbreaks of the genus Aedes, even in potable water. Despite the increasing number of toxicological studies about larvicides and insecticides-with an indication of continuous use-there have been few studies about the effects of pyriproxyfen in non-target species such as fish. This study evaluated the effects of pyriproxyfen on behavioral, cognitive, and endocrine parameters in zebrafish. We exposed adult zebrafish to different pyriproxyfen (Pestanal®) concentrations (0.125, 0.675, and 1.75 mg/l) for 96 h. We analyzed behavioral parameters, memory, cortisol levels, and gene expression of glucocorticoid receptor (gr) and corticotrophin-releasing factor (crf) after pyriproxyfen exposure. This exposure did not alter locomotion (distance or mean speed), anxiety-like behavior (latency to enter to the top zone of the tank or time in the top zone of the tank), and social or aggressive behavior. However, there was impaired inhibitory avoidance memory at all tested pyriproxyfen concentrations. Cortisol levels were reduced in exposed groups when compared to control or vehicle. However, gr and crf gene expression in pyriproxyfen-treated animals were unaltered when compared to control or vehicle groups. Taken together, these findings indicate that pyriproxyfen may induce cognitive impairment and altered cortisol levels in zebrafish, a non-target species.

P2X7R and PANX-1 channel relevance in a zebrafish larvae copper-induced inflammation model

Copper is a metal that participates in several essential reactions in living organisms, and it has been used as an inflammatory inducing agent in zebrafish larvae. In this study, we evaluated the effect P2X7 receptor and/or pannexin channel 1 (PANX-1) blockage in this inflammation model. To perform the experiments, 7 dpf larvae were exposed to 10 μM of copper and treated with 100 μM probenecid, PANX-1 inhibitor, and/or 300 nM A740003, a P2X7R selective antagonist. Larvae survival was assessed up to 24 h after treatments. The evaluation of larvae behavior was evaluated after acute (4 h) and chronic (24 h) exposure. The parameters of locomotor activity measured were: mobile time, average speed, distance and turn angle. We analyzed the gene expression of the P2X7 receptor, PANX1a and PANX1b channels and interleukins IL-10 and IL-1b after 24 h of treatment. Treatments did not decrease larval survival in the time interval studied. Changes in larvae locomotion were observed after the longest time of exposure to copper and the treatment with probenecid was able to reverse part of the effects caused by copper. No significant difference was observed in the oxidative stress assays and probenecid and copper treatment decrease partially PANX1a gene expression groups. The data presented herein shows the relevance of the blockage of P2X7-PANX-1 in copper-induced inflammation.

Co-exposure to nTiO2 impairs arsenic metabolism and affects antioxidant capacity in the marine shrimp Litopenaeus vannamei

Aquatic animals are vulnerable to arsenic (As) toxicity. However, rarely does a contaminant occur alone in the aquatic environment. For this reason, this study was conducted to evaluate whether titanium dioxide nanoparticles (nTiO₂) can interfere with the effects induced by As in Litopenaeus vannamei. Arsenic accumulation and metabolic capacity; expression and enzymatic activity of GSTΩ (glutathione-S-transferase omega isoform); antioxidant responses such as GSH, GR, and GST (reduced glutathione levels, glutathione reductase, and glutathione-S-transferase activity, respectively); and lipid peroxidation in the gills and hepatopancreas of shrimp were evaluated. The results are summarized as follows: (1) higher accumulation of As occurred in both tissues after exposure to As alone; (2) co-exposure to nTiO₂ affected the capacity to metabolize As; (3) GSTΩ gene expression was not modified, but its activity was decreased by co-exposure to both contaminants; (4) As alone increased the GSH levels in the hepatopancreas, and co-exposure to nTiO₂ reduced these levels in both tissues; (5) a decrease in the GST activity in the gills occurred with all treatments; (6) in the gills, GR activity was increased by As, and nTiO₂ reversed this increase, whereas in the hepatopancreas co-exposure inhibited enzyme activity; (7) only in the hepatopancreas lipid damage was observed when animals were exposed to As or nTiO₂ but not in co-exposure. The results showed that the As induces toxic effects in both tissues of shrimp and that co-exposure to nTiO₂ can potentiate these effects and decrease the capacity to metabolize As, favoring the accumulation of more toxic compounds.

Neurotoxicity in zebrafish exposed to carbon nanotubes: Effects on neurotransmitters levels and antioxidant system

Given the increasing use of carbon nanotubes (CNT) in several industries and technological applications, it is essential to perform in vivo toxicological studies with these nanomaterials to evaluate their potential ecotoxicity. Dopamine (DA) and serotonin (5HT) are key neurotransmitters for brain functions and behavioral responses. Determination of DA and 5HT were performed in brain samples from zebrafish Danio rerio exposed i.p. to single-walled CNT (SWCNT), besides analyzing acetylcholinesterase (AChE) and ectonucleotidases activity, lipid peroxidation and total antioxidant capacity. Results showed that treatment with SWCNT increased between 3 and 6-fold the concentration of DA and 5HT (p < 0.05). Similarly, a significant reduction (p < 0.05) in AChE activity was observed in the brains of SWCNT exposed zebrafish when compared to the control groups. Cholinergic, serotonergic, and dopaminergic systems, through AChE activity and serotonin and dopamine levels, respectively were affected by SWCNT in the zebrafish brain. Alterations in these neurotransmitters can potentially affect several physiological and behavioral that they control.

Iron chelator deferiprone rescues memory deficits, hippocampal BDNF levels and antioxidant defenses in an experimental model of memory impairment

Brain-derived neurotrophic factor (BDNF) plays a key role in neural development and physiology, as well as in pathological states. Post-mortem studies demonstrate that BDNF is reduced in the brains of patients affected by neurodegenerative diseases. Iron accumulation has also been associated to the pathogenesis of neurodegenerative diseases. In rats, iron overload induces persistent memory deficits, increases oxidative stress and apoptotic markers, and decreases the expression of the synaptic marker, synaptophysin. Deferiprone (DFP) is an oral iron chelator used for the treatment of systemic iron overload disorders, and has recently been tested for Parkinson's disease. Here, we investigated the effects of iron overload on BDNF levels and on mRNA expression of genes encoding TrkB, p75^NTR, catalase (CAT) and NQO1. We also aimed at investigating the effects of DFP on iron-induced impairments. Rats received iron or vehicle at postnatal days 12-14 and when adults, received chronic DFP or water (vehicle). Recognition memory was tested 19 days after the beginning of chelation therapy. BDNF measurements and expression analyses in the hippocampus were performed 24 h after the last day of DFP treatment. DFP restored memory and increased hippocampal BDNF levels, ameliorating iron-induced effects. Iron overload in the neonatal period reduced, while treatment with DFP was able to rescue, the expression of antioxidant enzymes CAT and NQO1.

Brain bioenergetics in rats with acute hyperphenylalaninemia

Phenylketonuria (PKU) is a disorder of phenylalanine (Phe) metabolism caused by deficient phenylalanine hydroxylase (PAH) activity. The deficiency results in increased levels of Phe and its metabolites in fluids and tissues of patients. PKU patients present neurological signs and symptoms including hypomyelination and intellectual deficit. This study assessed brain bioenergetics at 1 h after acute Phe administration to induce hyperphenylalaninemia (HPA) in rats. Wistar rats were randomized in two groups: HPA animals received a single subcutaneous administration of Phe (5.2 μmol/g) plus p-Cl-Phe (PAH inhibitor) (0.9 μmol/g); control animals received a single injection of 0.9% NaCl. In cerebral cortex, HPA group showed lower mitochondrial mass, lower glycogen levels, as well as lower activities of complexes I-III and IV, ATP synthase and citrate synthase. Higher levels of free Pi and phospho-AMPK, and higher activities of LDH, α-ketoglutarate dehydrogenase and isocitrate dehydrogenase were also reported in cerebral cortex of HPA animals. In striatum, HPA animals had higher LDH (pyruvate to lactate) and isocitrate dehydrogenase activities, and lower activities of α-ketoglutarate dehydrogenase and complex IV, as well as lower phospho-AMPK immunocontent. In hippocampus, HPA rats had higher mRNA expression for MFN1 and higher activities of α-ketoglutarate dehydrogenase and isocitrate dehydrogenase, but decreased activities of pyruvate dehydrogenase and complexes I and IV. In conclusion, our data demonstrated impaired bioenergetics in cerebral cortex, striatum and hippocampus of HPA rats.

Investigation into effects of antipsychotics on ectonucleotidase and adenosine deaminase in zebrafish brain

Antipsychotic agents are used for the treatment of psychotic symptoms in patients with several brain disorders, such as schizophrenia. Atypical and typical antipsychotics differ regarding their clinical and side-effects profile. Haloperidol is a representative typical antipsychotic drug and has potent dopamine receptor antagonistic functions; however, atypical antipsychotics have been developed and characterized an important advance in the treatment of schizophrenia and other psychotic disorders. Purine nucleotides and nucleosides, such as ATP and adenosine, constitute a ubiquitous class of extracellular signaling molecules crucial for normal functioning of the nervous system. Indirect findings suggest that changes in the purinergic system, more specifically in adenosinergic activity, could be involved in the pathophysiology of schizophrenia. We investigated the effects of typical and atypical antipsychotics on ectonucleotidase and adenosine deaminase (ADA) activities, followed by an analysis of gene expression patterns in zebrafish brain. Haloperidol treatment (9 µM) was able to decrease ATP hydrolysis (35%), whereas there were no changes in hydrolysis of ADP and AMP in brain membranes after antipsychotic exposure. Adenosine deamination in membrane fractions was inhibited (38%) after haloperidol treatment when compared to the control; however, no changes were observed in ADA soluble fractions after haloperidol exposure. Sulpiride (250 µM) and olanzapine (100 µM) did not alter ectonucleotidase and ADA activities. Haloperidol also led to a decrease in entpd2_mq, entpd3 and adal mRNA transcripts. These findings demonstrate that haloperidol is an inhibitor of NTPDase and ADA activities in zebrafish brain, suggesting that purinergic signaling may also be a target of pharmacological effects promoted by this drug.

Benzodiazepines alter nucleotide and nucleoside hydrolysis in zebrafish (Danio rerio) brain

Anxiety is characterized by unpleasant bodily sensations, such as pounding heart and intense fear. The therapy involves the administration of benzodiazepine drugs. Purinergic signaling participates in the induction of several behavioral patterns and their actions are inactivated by ectonucleotidases and adenosine deaminase (ADA). Since there is evidence about the involvement of purinergic system in the actions mediated by benzodiazepines, we evaluated the effects in vitro and in vivo of administration of diazepam and midazolam on nucleoside triphosphate diphosphohydrolases, ecto-5'-nucleotidase, and ADA activities in zebrafish brain, followed by the analysis of gene expression pattern of these enzymes and adenosine receptors (A1, A2a1, A2a2, A2b). The in vitro studies demonstrated that diazepam decreased ATP (66 % for 500 µM) and ADP hydrolysis (40-54 % for 10-500 µM, respectively). Midazolam decreased ATP (16-71 % for 10-500 µM, respectively) and ADP (48-73.5 % for 250-500 µM, respectively) hydrolysis as well as the ecto-ADA activity (26-27.5 % for 10-500 µM, respectively). AMP hydrolysis was decreased in animals treated with of 0.5 and 1 mg/L midazolam (32 and 36 %, respectively). Diazepam and midazolam decreased the ecto-ADA activity at 1.25 mg/L and 1 mg/L (31 and 33 %, respectively), but only 0.1 mg/L midazolam induced an increase (40 %) in cytosolic ADA. The gene expression analysis demonstrated changes on ecto-5'-nucleotidase, A1, A2a1, A2a2, and A2b mRNA transcript levels after acute treatment with benzodiazepines. These findings demonstrated that benzodiazepine exposure induces a modulation of extracellular nucleotide and nucleoside metabolism, suggesting the purinergic signaling may be, at least in part, related to benzodiazepine effects.

Spinal blockage of P/Q- or N-type voltage-gated calcium channels modulates functional and symptomatic changes related to haemorrhagic cystitis in mice

BACKGROUND AND PURPOSE

Spinal voltage-gated calcium channels (VGCCs) are pivotal regulators of painful and inflammatory alterations, representing attractive therapeutic targets. We examined the effects of epidural administration of the P/Q- and N-type VGCC blockers Tx3-3 and Phα1β, respectively, isolated from the spider Phoneutria nigriventer, on symptomatic, inflammatory and functional changes allied to mouse cyclophosphamide (CPA)-induced haemorrhagic cystitis (HC). The effects of P. nigriventer-derived toxins were compared with those displayed by MVIIC and MVIIA, extracted from the cone snail Conus magus.

EXPERIMENTAL APPROACH

HC was induced by a single i.p. injection of CPA (300 mg·kg(-1) ). Dose- and time-related effects of spinally administered P/Q and N-type VGCC blockers were assessed on nociceptive behaviour and macroscopic inflammation elicited by CPA. The effects of toxins were also evaluated on cell migration, cytokine production, oxidative stress, functional cystometry alterations and TRPV1, TRPA1 and NK1 receptor mRNA expression.

KEY RESULTS

The spinal blockage of P/Q-type VGCC by Tx3-3 and MVIIC or N-type VGCC by Phα1β attenuated nociceptive and inflammatory events associated with HC, including bladder oxidative stress and cytokine production. CPA produced a slight increase in bladder TRPV1 and TRPA1 mRNA expression, which was reversed by all the toxins tested. Noteworthy, Phα1β strongly prevented bladder neutrophil migration, besides HC-related functional alterations, and its effects were potentiated by co-injecting the selective NK1 receptor antagonist CP-96345.

CONCLUSIONS AND IMPLICATIONS

Our results shed new light on the role of spinal P/Q and N-type VGCC in bladder dysfunctions, pointing out Phα1β as a promising alternative for treating complications associated with CPA-induced HC.

Association between endothelial nitric oxide synthase gene polymorphism (-786T>C) and interleukin-6 in acute coronary syndrome

Atherosclerosis is morphologically an inflammatory disease, where endothelial dysfunction plays a key role in all the stages. The nitric oxide (NO) synthase 3 (NOS3) gene is responsible for the synthesis of endothelial NO synthase (eNOS) in humans and some genetic polymorphisms are considered "polymorphisms associated with risk" for the development of coronary artery diseases, such as acute coronary syndrome. Thus, the present study aimed to evaluate the influence of the -786T>C polymorphism of the eNOS gene on inflammatory and oxidative process. A prospective cohort study of 125 consecutive patients with clinical diagnosis of non-ST-elevation acute coronary syndromes was conducted. Patients were assessed using a standardized questionnaire. Blood samples were drawn to measure serum levels of high-sensitivity C-reactive protein, soluble CD40 ligand, interleukin-6 (IL-6), N-terminal prohormone of brain natriuretic peptide, immunoglobulin G antibodies against oxidized low-density lipoprotein. The genotypes for the -786T>C polymorphism in the 5'-flanking region of eNOS gene were determined. The -786C allele was found in 92 of 250 alleles (38.8%). No statistical association was observed between demographic and clinical characteristics and distribution of eNOS-786T>C polymorphism. We found that -786CC was associated with lower levels of IL-6. No significant differences were observed between the distribution of -786T>C polymorphism and other investigated markers.

Proline-induced changes in acetylcholinesterase activity and gene expression in zebrafish brain: reversal by antipsychotic drugs

Hyperprolinemia is an inherited disorder of proline metabolism and hyperprolinemic patients can present neurological manifestations, such as seizures, cognitive dysfunctions, and schizoaffective disorders. However, the mechanisms related to these symptoms are still unclear. In the present study, we evaluated the in vivo and in vitro effects of proline on acetylcholinesterase (AChE) activity and gene expression in the zebrafish brain. For the in vivo studies, animals were exposed at two proline concentrations (1.5 and 3.0mM) during 1h or 7 days (short- or long-term treatments, respectively). For the in vitro assays, different proline concentrations (ranging from 3.0 to 1000 μM) were tested. Long-term proline exposures significantly increased AChE activity for both treated groups when compared to the control (34% and 39%). Moreover, the proline-induced increase on AChE activity was completely reverted by acute administration of antipsychotic drugs (haloperidol and sulpiride), as well as the changes induced in ache expression. When assessed in vitro, proline did not promote significant changes in AChE activity. Altogether, these data indicate that the enzyme responsible for the control of acetylcholine levels might be altered after proline exposure in the adult zebrafish. These findings contribute for better understanding of the pathophysiology of hyperprolinemia and might reinforce the use of the zebrafish as a complementary vertebrate model for studying inborn errors of amino acid metabolism.

Gene expression and biochemical responses in brain of zebrafish Danio rerio exposed to organic nanomaterials: carbon nanotubes (SWCNT) and fullerenol (C60(OH)18-22(OK4))

Nanomaterials (NM) industry had grown in the last decade, although there are few studies concerning its potential toxicity effects on aquatic organisms. In this study the freshwater zebrafish (Danio rerio) was exposed to two kinds of carbon NM, single-wall carbon nanotubes (SWCNT) and fullerenol [C60(OH)18-22(OK4)] to analyze oxidative stress responses on fish brain. Adult zebrafish (mean mass: 0.52±0.01g) were submitted to intraperitoneal injections of SWCNT suspension and fullerenol solution (30mg/kg of fish), receiving one or two doses with a time interval of 24h. Results showed that total antioxidant capacity was lowered in brains of fish exposed 24h to fullerenol when compared to those from SWCNT treatment (p<0.05). After 48h, fullerenol induced higher expression of both catalytic and regulatory subunits of enzyme glutamate cysteine ligase when compared to control group (p<0.05), indicating an antioxidant behavior. In vitro assays showed a dual effect of SWCNT, since a pro-oxidant behavior was observed at low concentrations (0.1 and 1.0mg/L) and an antioxidant one at the highest concentration (10.0mg/L). Few biological responses were altered by this NM: decrease in total antioxidant capacity and induction of the expression of the transcription factor Nrf2 when compared to control group.

Functional and molecular characterization of kinin B1 and B 2 receptors in human bladder cancer: implication of the PI3Kγ pathway

Kinins and their receptors have been recently implicated in cancer. Using functional and molecular approaches, we investigated the relevance of kinin B1 and B2 receptors in bladder cancer. Functional studies were conducted using bladder cancer cell lines, and human biopsies were employed for molecular studies. Both B1 des-Arg(9)-BK and B2 BK receptor agonists stimulated the proliferation of grade 3-derived T24 bladder cancer cells. Furthermore, treatment with B1 and B2 receptor antagonists (SSR240612 and HOE140) markedly inhibited the proliferation of T24 cells. Only higher concentrations of BK increased the proliferation of the grade 1 bladder cancer cell line RT4, while des-Arg(9)-BK completely failed to induce its proliferation. Real-time PCR revealed that the mRNA expression of kinin receptors, particularly B1 receptors, was increased in T24 cells relative to RT4 cells. Data from bladder cancer human biopsies revealed that B1 receptor expression was increased in all tumor samples and under conditions of chronic inflammation. We also show novel evidence demonstrating that the pharmacological inhibition of PI3Kγ (phosphatidylinositol 3-kinase) with AS252424, concentration-dependently reduced T24 cell proliferation induced by BK or des-Arg(9)-BK. Finally, the incubation of T24 cells with kinin agonists led to a marked activation of the PI3K/AKT and ERK 1/2 signaling pathways, whereas p38 MAP kinase remained unaffected. Kinin receptors, especially B1 receptors, appear to be implicated in bladder cancer progression. It is tempting to suggest that selective kinin antagonists might represent potential alternative therapies for bladder cancer.

Ethylmalonic acid modulates Na+, K(+)-ATPase activity and mRNA levels in rat cerebral cortex

Ethylmalonic acid (EMA) accumulates in tissues of patients affected by short-chain acyl-CoA dehydrogenase deficiency and ethylmalonic encephalopathy, illnesses characterized by variable neurological symptoms. In this work, we investigated the in vitro and in vivo EMA effects on Na(+), K(+)-ATPase (NAK) activity and mRNA levels in cerebral cortex from 30-day-old rats. For in vitro studies, cerebral cortex homogenates were incubated in the presence of EMA at 0.5, 1, or 2.5 mM concentrations for 1 h. For in vivo experiments, animals received three subcutaneous EMA injections (6 μmol g(-1); 90-min interval) and were killed 60 min after the last injection. After that, NAK activity and its mRNA expression were measured. We observed that EMA did not affect this enzyme activity in vitro. In contrast, EMA administration significantly increased NAK activity and decreased mRNA NAK expression as assessed by semiquantitative reverse transcriptase polymerase chain reaction when compared with control group. Considering the high score of residues prone to phosphorylation on NAK, this profile can be associated with a possible regulation by specific phosphorylation sites of the enzyme. Altogether, the present results suggest that NAK alterations may be involved in the pathophysiology of brain damage found in patients in which EMA accumulates.

A ketogenic diet did not prevent effects on the ectonucleotidases pathway promoted by lithium-pilocarpine-induced status epilepticus in rat hippocampus

A Ketogenic Diet (KD) mimics the anticonvulsant effects of fasting, which are known to suppress seizures. The purinergic system has been investigated in the matter of epilepsy development, especially the nucleoside adenosine, which has been considered a natural brain anticonvulsant. During epileptic seizures, extracellular adenosine concentration rises rapidly to micromolar levels. Adenosine can exert its anticonvulsant functions, after its release by nucleoside bidirectional transport, or by production through the sequential catabolism of ATP by ectonucleotidases, such as E-NTPDases (ectonucleoside triphosphate diphosphohydrolases) and ecto-5'-nucleotidase. Here, we have investigated the effect of a ketogenic diet on the nucleotide hydrolysis and NTPDases expression in the lithium-pilocarpine (Li-Pilo) model of epilepsy. For the induction of Status Epileticus (SE), 21-day-old female Wistar rats received an i.p. injection of lithium chloride (127 mg/kg) and 18-19 h later an i.p. injection of pilocarpine hydrochloride (60 mg/kg). The control groups received an injection of saline. After induction of SE, the control and Li-Pilo groups received standard or ketogenic diets for 6 weeks. The lithium-pilocarpine exposure affected the ATP (a decrease of between 8 % and 16 %) and ADP (an increase of between 18 % and 22 %) hydrolysis in both groups whereas the diet did not impact the nucleotide hydrolysis. NTPDase2 and 3 mRNA expressions decreased in the Li-Pilo group (41 % and 42 %). This data highlights the participation of the purinergic system in the pathophysiology of this model of epilepsy, since nucleotide hydrolysis and NTPDase expressions were altered by Li-Pilo exposure, with no significant effects of the ketogenic diet. However, the interaction between purinergic signaling and a ketogenic diet on epilepsy still needs to be better elucidated.

Mild hyperhomocysteinemia alters extracellular adenine metabolism in rat brain

Since homocysteine (Hcy) is considered a risk factor to cerebral diseases and adenine nucleotides are important molecules to brain normal function, in the present study we investigated the effect of chronic mild hyperhomocysteinemia on ectonucleotidase activities and expression in rat cerebral cortex. The levels of ATP, ADP, AMP and adenosine (Ado) in cerebrospinal fluid (CSF) of adult rats also were evaluated by high-performance liquid chromatography. For the chronic chemically induced mild hyperhomocysteinemia, Hcy (0.03 μmol/g of body weight) was administered subcutaneously from the 30th to the 60th day of life. Control rats received saline solution in the same volumes. Results showed that Hcy significantly decreased nucleotide hydrolysis in the synaptosomal fraction and increased E-NTPDase1 and ecto-5'-nucleotidase transcripts in rat cerebral cortex. ATP levels were significantly increased, while Ado decreased in CSF of Hcy-treated rats. These findings suggest that the unbalance in ATP and Ado levels may be, at last in part, involved in the cerebral toxicity of mild hyperhomocysteinemia.

Arsenic alters behavioral parameters and brain ectonucleotidases activities in zebrafish (Danio rerio)

Arsenic (As) exposure has been associated with serious chronic health risk to humans including cancer and neurological disturbances. However, there are limited studies about the mechanisms behind its toxicity. In this study, adult zebrafish were exposed to several concentrations of As (0.05, 5, and 15 mg As/L; Na(2)HAsO(4) as As(V)) during 96 h to evaluate the zebrafish locomotor activity, anxiety, and brain extracellular nucleotide hydrolysis. We showed that 5 mg/L As is able to promote significant decrease in the locomotor activity as evaluated by the number of line crossings. In addition, animals treated with 5mg/L As presented an increase in time spent in the lower zone of the tank test, suggesting an anxiogenic effect. Considering that behavioral parameters, such as anxiety and locomotion, might be modulated by the purinergic system, we also evaluated the ectonucleotidase activities in zebrafish brain after a 96-h As exposure. A significant decrease in ATP, ADP, and AMP hydrolysis was observed at 0.05, 5, and 15 mg/L when compared to control group. These findings demonstrated that As might affect behavioral parameters and the ectonucleotidase activities in zebrafish, suggesting this enzyme pathway is a target for neurotoxic effects induced by As.

Iron exposure modifies acetylcholinesterase activity in zebrafish (Danio rerio) tissues: distinct susceptibility of tissues to iron overload

Iron is one the most abundant metals on the earth being essential for living organisms even though its free form can be toxic. The overload of this metal may be related with some disorders, like Alzheimer and Parkinson diseases, and hemochromatosis in the liver. The aim of the present study was to evaluate the effects of iron on acetylcholinesterase (AChE) activity in brain and liver of zebrafish and to investigate the possible correlation with the iron content in these tissues. Different corresponding concentrations of iron were tested using in vitro (0.018, 0.268, and 2.6 mM) and in vivo (1, 15, and 150 mg/l) assays. The in vitro studies showed that iron promoted a significant increase in AChE activity in brain (52%) and liver (53%) at the higher concentration (2.6 mM). In the in vivo assays, a significant increase in this enzyme activity was observed in the presence of 15 mg/l in both, brain (62%) and liver tissue (70%). Semiquantitative RT-PCR did not reveal significant changes in acetylthiocholinesterase mRNA levels. Moreover, we observed that iron content was significantly increased in liver tissue when exposed to 15 (226%) and 150 mg/l (200%). These results indicate that iron can promote significant alterations in AChE activity which probably is not directly related to the iron content in zebrafish tissues.

Biologic responses of bacteria communities living at the mucus secretion of common carp (Cyprinus carpio) after exposure to the carbon nanomaterial fullerene (C60)

Bacteria communities living in mucus secretions of common carp Cyprinus carpio (Cyprinidae) were exposed to the organic nanomaterial fullerene (C(60)) to evaluate its potential bactericidal effects. End points analyzed were viability, growth, reactive oxygen species (ROS) concentration, and total antioxidant competence against peroxyl radicals. Viability was not affected (p > 0.05), whereas growth was arrested (p < 0.05) after 3 hours of exposure to the three concentration of C(60) assayed (0.1, 1, and 10 mg/L). Levels of RO measured at different C(60) concentration showed that some colonies were reactive (significant dose-response relation, p < 0.05) to C(60), whereas others were not. The nonreactive colonies to C(60) presented higher antioxidant competence to peroxyl radicals compared with the reactive colonies (p < 0.05). The strains isolated and identified by polymerase chain reaction (PCR) products of 16S rRNA showed a predominance of Aeromonas genus between all the isolated Gram-negative bacteria. Thus, the present results indicate that C(60) affects bacterial communities that live in mucus secretions of common carp.

Inhibitory effect of lithium on nucleotide hydrolysis and acetylcholinesterase activity in zebrafish (Danio rerio) brain

Lithium has been used as an effective antimanic drug in humans and it is well known for its effects on neuropsychiatric disorders and neuronal communication. ATP and adenosine are important signaling molecules, and most nerves release ATP as a fast co-transmitter together with classical neurotransmitters such as acetylcholine. In this study, we evaluated the in vitro and in vivo effects of lithium on acetylcholinesterase and ectonucleotidase activities in zebrafish brain. There was a significant inhibition of ADP hydrolysis after in vivo exposure to lithium at 5 and 10 mg/l (27.6% and 29% inhibition, respectively), whereas an inhibitory effect was observed for AMP hydrolysis only at 10 mg/l (30%). Lithium treatment in vivo also significantly decreased the acetylcholinesterase activity at 10 mg/l (21.9%). The mRNA transcript levels of the genes encoding for these enzymes were unchanged after exposure to 5 and 10 mg/l lithium chloride. In order to directly evaluate the action of lithium on enzyme activities, we tested the in vitro effect of lithium at concentrations ranging from 1 to 1000 μM. There were no significant changes in zebrafish brain ectonucleotidase and acetylcholinesterase activities at all concentrations tested in vitro. Our findings show that lithium treatment can alter ectonucleotidase and acetylcholinesterase activities, which may regulate extracellular nucleotide, nucleoside, and acetylcholine levels. These data suggest that cholinergic and purinergic signaling may be targets of the pharmacological effects induced by this compound.

Nucleoside triphosphate diphosphohydrolases role in the pathophysiology of cognitive impairment induced by seizure in early age

Studies have shown that seizures in young animals lead to later cognitive deficits. There is evidence that long-term potentiation (LTP) and long-term depression (LTD) might contribute to the neural basis for learning and memory mechanism and might be modulated by ATP and/or its dephosphorylated product adenosine produced by a cascade of cell-surface transmembrane enzymes, such as E-NTPDases (ecto-nucleoside triphosphate diphosphohydrolases) and ecto-5'-nucleotidase. Thus, we have investigated if hippocampal ecto-nucleotidase activities are altered at different time periods after one episode of seizure induced by kainic acid (KA) in 7 days old rats. We also have evaluated if 90 day-old rats previously submitted to seizure induced by KA at 7 days of age presented cognitive impairment in Y-maze behavior task. Our results have shown memory impairment of adult rats (Postnatal day 90) previously submitted to one single seizure episode in neonatal period (Postnatal day 7), which is accompanied by an increased ATP hydrolysis in hippocampal synaptosomes. The metabolism of ATP evaluated by HPLC confirmed that ATP hydrolysis was faster in adult rats treated with KA in neonatal period than in controls. Surprisingly, the mRNA and protein levels as seen by PCR and Western blot, respectively, were not altered by the KA administration in early age. Since we have found an augmented hydrolysis of ATP and this nucleotide seems to be important to LTP induction, we could assume that impairment of memory and learning observed in adult rats which have experienced a convulsive episode in postnatal period may be a consequence of the increased ATP hydrolysis. These findings correlate the purinergic signaling to the cognitive deficits induced by neonatal seizures and contribute to a better understanding about the mechanisms of seizure-induced memory dysfunction.

Aluminum exposure alters behavioral parameters and increases acetylcholinesterase activity in zebrafish (Danio rerio) brain

Aluminum is a metal that is known to impact fish species. The zebrafish has been used as an attractive model for toxicology and behavioral studies, being considered a model to study environmental exposures and human pathologies. In the present study, we have investigated the effect of aluminum exposure on brain acetylcholinesterase activity and behavioral parameters in zebrafish. In vivo exposure of zebrafish to 50 μg/L AlCl(3) for 96 h at pH 5.8 significantly increased (36%) acetylthiocholine hydrolysis in zebrafish brain. There were no changes in acetylcholinesterase (AChE) activity when fish were exposed to the same concentration of AlCl(3) at pH 6.8. In vitro concentrations of AlCl(3) varying from 50 to 250 μM increased AChE activity (28% to 33%, respectively). Moreover, we observed that animals exposed to AlCl(3) at pH 5.8 presented a significant decrease in locomotor activity, as evaluated by the number of line crossings (25%), distance traveled (14.1%), and maximum speed (24%) besides an increase in the absolute turn angle (12.7%). These results indicate that sublethal levels of aluminum might modify behavioral parameters and acetylcholinesterase activity in zebrafish brain.

Candimine-induced cell death of the amitochondriate parasite Trichomonas vaginalis

Candimine (1), an alkaloid from the bulbs of Hippeastrum morelianum, was found to be cytotoxic for the amitochondriate parasite Trichomonas vaginalis. Candimine (1) induced cell death with an unprecedented group of effects that failed to fulfill the criteria for apoptosis and apoptosis-like death already reported in trichomonads. Arrest of the parasite cell cycle, and morphologic and ultrastructural alterations, including marked cytoplasmic vacuolization, were induced by 1. The present findings suggest some similarities to paraptotic cell death, described for multicellular organisms. This study contributes to both a better understanding of the biological effects of 1 and T. vaginalis cell biology.

Taurine prevents enhancement of acetylcholinesterase activity induced by acute ethanol exposure and decreases the level of markers of oxidative stress in zebrafish brain

Ethanol (EtOH) is a drug widely consumed throughout the world that promotes several neurochemical disorders. Its deleterious effects are generally associated with modifications in oxidative stress parameters, signaling transduction pathways, and neurotransmitter systems, leading to distinct behavioral changes. Taurine (2-aminoethanesulfonic acid) is a β-amino acid not incorporated into proteins found in mM range in the central nervous system (CNS). The actions of taurine as an inhibitory neurotransmitter, neuromodulator, and antioxidant make it attractive for studying a potential protective role against EtOH-mediated neurotoxicity. In this study, we investigated whether acute taurine cotreatment or pretreatment (1 h) prevent EtOH-induced changes in acetylcholinesterase (AChE) activity and in oxidative stress parameters in zebrafish brain. The results showed that EtOH exposure (1% in volume) during 1 h increased AChE activity, whereas the cotreatment with 400 mg·L(-1) taurine prevented this enhancement. A similar protective effect of 150 and 400 mg·L(-1) taurine was also observed when the animals were pretreated with this amino acid. Taurine treatments also prevented the alterations promoted in superoxide dismutase and catalase activities by EtOH, suggesting a modulatory role in enzymatic antioxidant defenses. The pretreatment with 150 and 400 mg·L(-1) taurine significantly increased the sulfydryl levels as compared to control and EtOH groups. Moreover, 150 and 400 mg·L(-1) taurine significantly decreased thiobarbituric acid reactive species (TBARS) levels, but the cotreatment with EtOH plus 400 mg·L(-1) taurine did not prevent the EtOH-induced lipoperoxidation. In contrast, the pretreatment with 150 and 400 mg·L(-1) taurine prevented the TBARS increase besides decreased the basal levels of lipid peroxides. Altogether, our data showed for the first time that EtOH induced oxidative stress in adult zebrafish brain and reinforce the idea that this vertebrate is an attractive alternative model to evaluate the beneficial effect of taurine against acute EtOH exposure.

In vitro effects of antiepileptic drugs on acetylcholinesterase and ectonucleotidase activities in zebrafish (Danio rerio) brain

Carbamazepine (CBZ), phenytoin (PHT), and gabapentine (GBP) are classical antiepileptic drugs (AEDs) that act through a variety of mechanisms. We have tested the in vitro effects of CBZ, PHT, and GBP at different concentrations on ectonucleotidase and acetylcholinesterase activities in zebrafish brain. CBZ inhibited ATP hydrolysis at 1000 microM (32%) whereas acetylcholine hydrolysis decreased at 500 microM (25.2%) and 1000 microM (38.7%). PHT increased AMP hydrolysis both at 500 microM (65%) and 1000 microM (64.8%). GBP did not promote any significant changes on ectonucleotidase and acetylcholinesterase activities. These results have shown that CBZ can reduce NTPDase (nucleoside triphosphate diphosphohydrolase) and PHT enhance ecto 5'-nucleotidase activities. Therefore, it is possible to suggest that the AEDs induced-effects on ectonucleotidases are related to enzyme anchorage form. Our findings have also shown that high CBZ concentrations inhibit acetylcholinesterase activity, which can induce an increase of acetylcholine levels. Taken together, these results showed a complex interaction among AEDs, purinergic, and cholinergic systems, providing a better understanding of the AEDs pharmacodynamics.

Trichomonas vaginalis nucleoside triphosphate diphosphohydrolase and ecto-5'-nucleotidase activities are inhibited by lycorine and candimine

Drug discovery from plants plays an important role in the pharmaceutical therapy field and the alkaloids lycorine and candimine are candidates for this purpose. Trichomonas vaginalis is a parasite that infects the human urogenital tract and causes trichomonosis, the most prevalent non-viral sexually transmitted disease. Ecto-nucleotidases including nucleoside triphosphate diphosphohydrolase (NTPDase) members, which hydrolyses extracellular ATP (adenosine triphosphate) and ADP (adenosine diphosphate), and ecto-5'-nucleotidase, which hydrolyses AMP (adenosine monophosphate), have been characterized in T. vaginalis. Because purine nucleotides are released from cells under physiological and stress conditions, the goal of this study was to evaluate the effect of lycorine and candimine on T. vaginalis NTPDase and ecto-5'-nculeotidase activities. The alkaloids (50 to 250microM) were tested against both long-term-grown and clinical isolates. Specific enzymatic activities were expressed as nmolPi released/min/mg protein. The effect of both alkaloids at NTPDase A and B expression levels was investigated. When the alkaloids were added directly to the reaction mixture, no effect on ATP, ADP or AMP hydrolysis was observed. NTPDase and ecto-5'-nucleotidase activities were strongly inhibited by candimine and lycorine on 24h-treated parasites. This effect was abolished when 24-treated parasites were innoculated in a culture medium without alkaloid. Transcript levels of NTPDase A or B were not altered by the alkaloids. Considering the cytotoxic and proinflammatory roles of ATP besides the anti-inflammatory effects of adenosine, the regulation of extracellular nucleotide levels could be relevant in increasing susceptibility of T. vaginalis to host immune response in the presence of lycorine and candimine.

Association between 894G>T endothelial nitric oxide synthase gene polymorphisms and metabolic syndrome

Metabolic syndrome (MS) is a cluster of cardiovascular risk factors such as hypertension, dyslipidemia, obesity and type II diabetes. Here, we performed a case-control study analyzing the association between 894G>T endothelial nitric oxide synthase gene polymorphism (NOS3) and MS in 616 subjects. Genotype frequencies were TT= 9.3%, GG= 37.2 and TG= 53.6% and the allelic frequencies were T=0.36 and G= 0.64. We observed a higher TT genotype frequency in the male MS group than control subjects (p=0.02), independent of other variables. We found an association between hypertension and TT genotype in females. Our data suggests that 894G>T plays a significant role in the mechanistic interaction between metabolic risk such as hypertension and MS, although sex-related differences may exist.

Typical and atypical antipsychotics alter acetylcholinesterase activity and ACHE expression in zebrafish (Danio rerio) brain

Antipsychotic agents are widely used for the treatment of psychotic symptoms in patients with several brain disorders. Antipsychotic drugs principally affect dopamine systems with the newer ones also affecting serotonin, norepinephrine, and histamine systems. Other transmitter systems can be involved with selected antipsychotic drugs but effects on cholinergic system are less known. Considerable evidence has shown that complex interactions between dopaminergic and cholinergic systems are critical for the proper regulation of motor control and memory. These neurotransmitter systems have been studied in zebrafish, which has recently become a focus of neurobehavioral studies. Therefore, we have evaluated the in vitro and in vivo effects of sulpiride, olanzapine, and haloperidol on acetylcholinesterase activity and ache expression pattern in zebrafish brain. For in vitro studies, all drugs were able to promote a decrease on acetylcholinesterase activity. For in vivo studies, olanzapine and sulpiride exposure did not change acetylcholinesterase activity. In contrast, this enzyme activity was significantly increased at 5 and 9 microM haloperidol (29.9% and 20.4%, respectively). Haloperidol exposure was able to increase acetylcholinesterase mRNA transcripts. These findings have suggested that the alterations in zebrafish acetylcholinesterase could reveal molecular mechanisms related to cholinergic signaling induced by antipsychotic treatment.

Ethanol alters acetylcholinesterase activity and gene expression in zebrafish brain

Alcohol abuse is a health problem throughout the world and alcohol consumption is linked to the occurrence of several pathological conditions. Acute ethanol administration exerts a variety of actions on the central nervous system (CNS). Zebrafish has been used as an attractive model system to investigate behavioral and neurochemical changes promoted by alcohol intoxication. Here we investigated the in vitro and in vivo effects promoted by ethanol and its metabolites on zebrafish brain acetylcholinesterase (AChE). There was a significant increase of AChE (33%) activity after acute 1% ethanol exposure. However, ethanol in vitro did not alter AChE activity. Acetaldehyde, the first metabolite of alcohol metabolism, promoted a dose-dependent decrease (15%, 27.5% and 46.5%) at 0.25%, 0.5% and 1%, respectively. Acetate, a product of acetaldehyde degradation, did not change AChE activity. Furthermore, the acute ethanol exposure was able to inhibit AChE transcripts at 0.5% and 1%. These findings suggest that the alterations on zebrafish AChE could reveal molecular mechanisms related to cholinergic signaling in alcoholism.

An efficient gene transfer system for hematopoietic cell line using transient and stable vectors

The hematopoietic system represents an interesting model for gene transfer protocols. Here, we have evaluated the efficiency of a gene transfer system using the polycationic compound SuperFect (Qiagen) and the K562 hematopoietic cell line. Transient and stable vectors carrying the enhanced green fluorescent protein (EGFP) reporter gene were employed. The stable vector was constructed based on Epstein-Barr virus sequences such as EBV oriP (origin of replication) and EBNA (EBV nuclear antigen)-1, both for DNA replication. The transfection efficiency of the viable cells was estimated by flow cytometry at approximately 98% for transient and stable vectors. Transiently transfected cells presented optimal EGFP expression until day 2 when fluorescence started to decrease. In contrast, stable transfectants continuously expressed the marker gene product for 10 weeks in the presence of G418. Our results represent an efficient gene transfer method for K562 hematopoietic cells and may be used as an alternative approach for further gene transfer studies involving hematopoietic cells.

Characterisation of an ATP diphosphohydrolase (Apyrase, EC 3.6.1.5) activity in Trichomonas vaginalis

In the present report the enzymatic properties of an ATP diphosphohydrolase (apyrase, EC 3.6.1.5) in Trichomonas vaginalis were determined. The enzyme hydrolyses purine and pyrimidine nucleoside 5'-di- and 5'-triphosphates in an optimum pH range of 6.0--8.0. It is Ca(2+)-dependent and is insensitive to classical ATPase inhibitors, such as ouabain (1 mM), N-ethylmaleimide (0.1 mM), orthovanadate (0.1 mM) and sodium azide (5 mM). A significant inhibition of ADP hydrolysis (37%) was observed in the presence of 20 mM sodium azide, an inhibitor of ATP diphosphohydrolase. Levamisole, a specific inhibitor of alkaline phosphatase, and P(1), P(5)-di (adenosine 5'-) pentaphosphate, a specific inhibitor of adenylate kinase, did not inhibit the enzyme activity. The enzyme has apparent K(m) (Michaelis Constant) values of 49.2+/-2.8 and 49.9+/-10.4 microM and V(max) (maximum velocity) values of 49.4+/-7.1 and 48.3+/-6.9 nmol of inorganic phosphate x min(-1) x mg of protein(-1) for ATP and ADP, respectively. The parallel behaviour of ATPase and ADPase activities and the competition plot suggest that ATP and ADP hydrolysis occur at the same active site. The presence of an ATP diphosphohydrolase activity in T. vaginalis may be important for the modulation of nucleotide concentration in the extracellular space, protecting the parasite from the cytolytic effects of the nucleotides, mainly ATP.

A chitinase encoding gene (chit1 gene) from the entomopathogen Metarhizium anisopliae: isolation and characterization of genomic and full-length cDNA

There are no reports to date of entire gene sequences coding for chitinolytic enzymes from entomopathogenic fungi, even though these enzymes act synergistically with proteolytic enzymes to solubilize insect cuticle during the key step of host penetration, having considerable importance in the biological control of some insect pests. This paper reports the complete nucleotide sequence and analysis of the chromosomal and full-length cDNA copies of the regulated gene (chit1) coding one of the chitinases produced by the biocontrol agent Metarhizium anisopliae. Degenerated primers, encompassing conserved regions of other fungal chitinases, were used to amplify a 650-bp DNA fragment, which was used to isolate genomic and cDNA clones from M. anisopliae. Albeit at least two different chitinases are characterized in this fungus, only one chit gene was isolated. The chit1 gene is interrupted by three short typical fungal introns and has a 1,521-bp ORF, which encodes a protein of 423 amino acids with a stretch of 35 amino acid residues displaying characteristics of signal peptide. The deduced sequence of the mature protein predicts a 42-kDa protein with pI of 5.8. Southern analysis of genomic DNA indicates a single copy of chit1 in the M. anisopliae genome.

High frequency gene conversion among benomyl resistant transformants in the entomopathogenic fungus Metarhizium anisopliae

Three different methods, (i) PEG, (ii) electroporation and (iii) biolistic, were employed to transform Metarhizium anisopliae using benomyl resistance as a selectable marker. Transformation frequencies and mitotic stability varied for each method, from 0.8 to 6.9 transformants micrograms-1 of DNA and 46%, respectively, by the PEG method; 1.3 to 1.8 transformants micrograms-1 of DNA and 67% by electroporation; and 32 to 201 transformants micrograms-1 of DNA and 90% by biolistic. We demonstrate by PCR that 60% of the transformants were generated by gene conversion.