Trypanosoma cruzi nucleoside diphosphate kinase 1 ( TcNDPK1) has a broad nuclease activity

Here, we present the characterization of a trypanosomatid nucleoside diphosphate kinase (TcNDPK1) exhibiting nuclease activity. This is the first identification of a NDPK with this property in trypanosomatid organisms. The recombinant TcNDPK1 protein cleaves not only linear DNA, but also supercoiled plasmid DNA. Additionally, TcNDPK1 is capable of degrading Trypanosoma cruzi genomic DNA. ATP or ADP did not affect the nuclease activity, while the absence of Mg2+ completely inhibits this activity. NDPK and nuclease activities were inhibited at the same temperature, suggesting the presence of related catalytic sites. Furthermore, phenogram analysis showed that TcNDPK1 is close to Drosophila melanogaster and human NDPKs. The unspecific nuclease activity could suggest a participation in cellular processes such as programmed cell death.     

Analyzing Beach Recreationists’ Preferences for the Reduction of Jellyfish Blooms: Economic Results from a Stated-Choice Experiment in Catalonia,Spain

Jellyfish outbreaks and their consequences appear to be on the increase around the world, and are becoming particularly relevant in the Mediterranean. No previous studies have quantified tourism losses caused by jellyfish outbreaks. We used a stated-choice questionnaire and a Random Utility Model to estimate the amount of time respondents would be willing to add to their journey, in terms of reported extra travel time, in order to reduce the risk of encountering jellyfish blooms in the Catalan coast. The estimation results indicated that the respondents were willing to spend on average an additional 23.8% of their travel time to enjoy beach recreation in areas with a lower risk of jellyfish blooms. Using as a reference the opportunity cost of time, we found that the subsample of individuals who made a trade-off between the disutility generated by travelling longer in order to lower the risk of jellyfish blooms, and the utility gained from reducing this risk, are willing to pay on average €3.20 per beach visit. This estimate, combined with the respondents’ mean income, yielded annual economic gains associated with reduction of jellyfish blooms on the Catalan coast around €422.57 million, or about 11.95% of the tourism expenditures in 2012. From a policy-making perspective, this study confirms the importance of the economic impacts of jellyfish blooms and the need for mitigation strategies. In particular, providing daily information using social media applications or other technical devices may reduce these social costs. The current lack of knowledge about jellyfish suggests that providing this information to beach recreationists may be a substantially effective policy instrument for minimising the impact of jellyfish blooms.     

A case of ataxia telangiectasia with unbalanced glucose 6-phosphate dehydrogenase mosaicism in the granulocytic/monocytic lineages.

Ataxia telangiectasia is a genetically determined disease with multi-system abnormalities and a high incidence of neoplasia. In order to define the nature of the association between ataxia telangiectasia and malignancy, we investigated a patient with the disease and heterozygote for the Mediterranean variant of the X-linked marker glucose 6-phosphate dehydrogenase. Enzymatic mosaicism in hemopoietic and nonhemopoietic cells was evaluated with the 2-deoxy glucose 6-phosphate technique. While erythrocytes, platelets, and lymphocytes expressed the same double-enzyme phenotype as tissues of nonhemopoietic origin, granulocytes and monocytes expressed almost exclusively the Mediterranean-type enzyme. We suggest that, as the result of genetic instability at the hemopoietic stem-cell level, the granulocytic/monocytic progeny enjoyed a proliferative advantage and became the predominant clone.     

Content of dolichol and retinol in isolated rat non-parenchymal liver cells

The liver sinusoids, that are considered as a functional unit, harbour four types of sinusoidal cells (Ito, Kupffer, endothelial and pit cells). Dolichol content has been determined in many tissues and subcellular compartments, alteration has been reported in many types of liver injury, but until now no data are available on its content in every type of sinusoidal non-parenchymal liver cells. Dolichol and retinol metabolism might intersect in their traffic in biological membranes. Intercellular as well as intracellular exchange of retinoids is an essential element of important processes occurring in liver cells. It has been suggested that the role of dolichol, besides being a carrier of oligosaccharides in the biosynthesis of N-linked glycoproteins, may be to modify membrane fluidity and permeability, and facilitate fusion of membranes. Dolichol in the membrane is intercalated between the two halves of the phospholipid bilayer, but its exact disposition is not known and the movement and distribution of retinoid in membranes may vary with the geometry of the membranes. Therefore the aim of this study is to obtain a global understanding of the sinusoidal system regarding dolichol and retinol content in each type of isolated rat liver sinusoidal cell, in normal conditions and after vitamin A administration. The information that can be drawn from the present results is that with normal vitamin A status of the animal, the dolichol content is almost uniform in all liver cells. After vitamin A supplementation, a great increase of dolichol, together with the known increase of retinol, can be measured only in a subpopulation of the Ito cells, the Ito-1 subfraction. Therefore in the cells that are present in the hepatic sinusoid, different pools of dolichol may have separate functions. Because retinol traffic among cells, membranes and plasma still remains to be fully understood, roles of dolichol in the exchange of vitamin A among sinusoidal liver cells are discussed. © 1998 John Wiley & Sons, Ltd.     

Phytomonas: transport of amino acids, hexoses and polyamines

Phytomonas cells (Phytomonas Jma) isolated from the latex of Jatropha macrantha were assayed for amino acid, hexose and polyamine transport. Results showed high transport rates for glucose and fructose (193 and 128 pmol min(-1) 10(-7) cells, respectively) and lower, but significant rates, for proline, arginine, cysteine and glutamate (between 1.7 and 5.8 pmol min(-1) 10(-7) cells). Minor transport activities were observed for serine, glycine and aspartate (<1 pmol min(-1) 10(-7) cells). Amino acid transport processes do not seem to be regulated by starvation or during the growth phases. Polyamine transport was also evaluated showing a clear preference for spermidine over putrescine (3.4 and 0.4 pmol min(-1) 10(-7) cells, respectively). This work represents the first report on metabolite transport in phytomonads.     

Lysine transporters in human trypanosomatid pathogens

In previous studies we characterized arginine transporter genes from Trypanosoma cruzi and Leishmania donovani, the etiological agents of chagas disease and kala azar, respectively, both fatal diseases in humans. Unlike arginine transporters in higher eukaryotes that transport also lysine, these parasite transporters translocate only arginine. This phenomenon prompted us to identify and characterize parasite lysine transporters. Here we demonstrate that LdAAP7 and TcAAP7 encode lysine-specific permeases in L. donovani and T. cruzi, respectively. These two lysine permeases are both members of the large amino acid/auxin permease family and share certain biochemical properties, such as specificity and Km. However, we evidence that LdAAP7 and TcAAP7 differ in their regulation and localization, such differences are likely a reflection of the dissimilar L. donovani and T. cruzi life cycles. Failed attempts to delete both alleles of LdAAP7 support the premise that this is an essential gene that encodes the only lysine permeases expressed in L. donovani promastigotes and T. cruzi epimastigotes, respectively.     

Molecular and functional characterization of a spermidine transporter (TcPAT12) from Trypanosoma cruzi

Trypanosoma cruzi, the etiological agent of Chagas' disease, is the only eukaryotic cell which lacks the ability to synthesize polyamines de novo. In this work, we describe for the first time the molecular and biochemical properties of a high-affinity spermidine transporter from T. cruzi. The transporter gene TcPAT12 was functionally expressed in Xenopus laevis oocytes, showing high levels of spermidine uptake. Similar apparent affinity constants for spermidine uptake were obtained when comparing T. cruzi epimastigotes and heterologous expressed TcPAT12 in X. laevis. In addition, TcPAT12 also transports putrescine and the amino acid l-arginine at lower rates than spermidine.     

Site I on human albumin: differences in the binding of (R)- and (S)-warfarin.

The binding of drugs known to interact with area I on human serum albumin (HSA) was investigated using a chiral stationary phase obtained by anchoring HSA to a silica matrix. In particular, this high-pressure affinity chromatography selector was employed to study the binding properties of the individual enantiomers of warfarin. The pH and composition of the mobile phase modulate the enantioselective binding of warfarin. Displacement chromatography experiments evidenced significant differences in the binding of the warfarin enantiomers to site I. The (S)-enantiomer was shown to be a direct competitor for (R)-warfarin, while (R)-warfarin was an indirect competitor for the (S)-enantiomer. Salicylate directly competed with (R)-warfarin and indirectly with (S)-warfarin. This behavior was confirmed by difference CD experiments, carried out with the same [HSA]/[drug] system in solution.     

Doxorubicin Impairs the Insulin-Like Growth Factor-1 System and Causes Insulin-Like Growth Factor-1 Resistance in Cardiomyocytes

BackgroundInsulin-like growth factor-1 (IGF-1) promotes the survival of cardiomyocytes by activating type 1 IGF receptor (IGF-1R). Within the myocardium, IGF-1 action is modulated by IGF binding protein-3 (IGFBP-3), which sequesters IGF-1 away from IGF-1R. Since cardiomyocyte apoptosis is implicated in anthracycline cardiotoxicity, we investigated the effects of the anthracycline, doxorubicin, on the IGF-1 system in H9c2 cardiomyocytes.ConclusionsDoxorubicin down-regulates IGF-1R and up-regulates IGFBP-3 via p53 and oxidative stress in H9c2 cells. This leads to resistance to IGF-1 that may contribute to doxorubicin-initiated apoptosis. Further studies are needed to confirm these findings in human cardiomyocytes and explore the possibility of manipulating the IGF-1 axis to protect against anthracycline cardiotoxicity.     

An expanded adenylate kinase gene family in the protozoan parasite Trypanosoma cruzi

Adenylate kinases supply energy routes in cellular energetic homeostasis. In this work, we identified and characterized the adenylate kinase activity in extracts from the flagellated parasite Trypanosoma cruzi, the causative agent of Chagas' disease. Adenylate kinase activity was detected in different subcellular fractions and the cytosolic isoform was biochemically characterized. Cytosolic adenylate kinase specific activity increases continuously during the epimastigote growth and is down-regulated when other soluble phosphotransferase, arginine kinase, is overexpressed. Six different genes of adenylate kinase isoforms were identified and the mRNA expression was confirmed by RT-PCR and Northern Blot. Three open reading frames coding for different enzyme isoforms named TzADK1, TzADK2 and TzADK5 were cloned and functionally expressed in E. coli. This work reports an unusually large number of genes of adenylate kinases and suggests a coordinated regulation of phosphotransferase-mediated ATP regenerating pathways in the unicellular parasite Trypanosoma cruzi.