Cloning and characterisation of the Equilibrative Nucleoside Transporter family of Trypanosoma cruzi: ultra-high affinity and selectivity to survive in the intracellular niche

Background: Trypanosoma cruzi, the causative agent of Chagas' disease is unable to synthesise its own purines and relies on salvage from the host. In other protozoa, purine uptake has been shown to be mediated by Equilibrative Nucleoside Transporters (ENTs). Methods: To investigate the functionality of T. cruzi-encoded ENT transporters, its four putative ENT genes (TcrNB1, TcrNB2, TcrNT1 and TcrNT2) were cloned and expressed in genetically adapted Trypanosoma brucei procyclic cells from which the nucleobase transporter locus was deleted. Results: TcrNB1 displayed very high affinity for hypoxanthine (Km 93.8 ± 4.7 nM for) and guanine, and moderate affinity for adenine. TcrNT1 was found to be a high-affinity guanosine/inosine transporter (inosine Km is 1.0 ± 0.03 μM; guanosine Ki is 0.92 ± 0.2 μM). TcrNT2 encoded a high-affinity thymidine transporter (Km = 223.5 ± 7.1 nM) with a clear preference for 2’-deoxypyrimidines. TcrNB2, whose activity could not be determined in our system, could be a low-affinity purine nucleobase transporter, given its sequence and predicted structural similarities to Leishmania major NT4. All 4 transporter genes were highly expressed in the amastigote forms, with much lower expression in the non-dividing stages. Conclusions: The data appear to show that, surprisingly, T. cruzi has a preference for oxopurines over aminopurines and efficiently transports 2′-deoxypyrimidines. The T. cruzi ENTs display exceptionally high substrate affinity as an adaptation to their intracellular localisation. General significance: This study reports the first cloning of T. cruzi purine and pyrimidine transporters, including the first gene encoding a pyrimidine-selective protozoan transporter

Flavonóides isolados do pólen coletado pela abelha Scaptotrigona bipunctata (canudo)

Pólen de abelhas é uma mistura de pólens florais coletados pelas abelhas com ampla variação na sua composição. Investigação do pólen coletado pela abelha sem ferrão Scaptotrigona bipunctata levou a quatro agliconas de flavonóides: miricetina, dihidromiricetina, quercetina e isoramnetina. As estruturas foram estabelecidas a partir de dados espectroscópicos (NMR) das substâncias naturais

Introduction of the anti-apoptotic baculovirus p35 gene in passion fruit induces herbicide tolerance, reduced bacterial lesions, but does not inhibits passion fruit woodiness disease progress induced by cowpea aphid-borne mosaic virus (CABMV

The introduction of anti-apoptotic genes into plants leads to resistance to environmental stress and broad-spectrum disease resistance. The anti-apoptotic gene (p35) from a baculovirus was introduced into the genome of passion fruit plants by biobalistics. Eleven regenerated plants showed the presence of the p35 gene by PCR and/or dot blot hybridization. Transcriptional analysis of regenerated plants showed the presence of specific p35 transcripts in 9 of them. Regenerated plants containing the p35 gene were inoculated with the cowpea aphid-borne mosaic virus (CABMV), the bacterium Xanthomonas axonopodis pv passiflorae, and the herbicide, glufosinate, (Syngenta). None of the plants showed resistance to CABMV. Regenerated plants (p35+) showed less than half of local lesions showed by non-transgenic plants when inoculated with X. axonopodis and some p35+ plants showed increased tolerance to the glufosinate herbicide when compared to non-transgenic plant

Numerical convergence of the block-maxima approach to the Generalized Extreme Value distribution

In this paper we perform an analytical and numerical study of Extreme Value distributions in discrete dynamical systems. In this setting, recent works have shown how to get a statistics of extremes in agreement with the classical Extreme Value Theory. We pursue these investigations by giving analytical expressions of Extreme Value distribution parameters for maps that have an absolutely continuous invariant measure. We compare these analytical results with numerical experiments in which we study the convergence to limiting distributions using the so called block-maxima approach, pointing out in which cases we obtain robust estimation of parameters. In regular maps for which mixing properties do not hold, we show that the fitting procedure to the classical Extreme Value Distribution fails, as expected. However, we obtain an empirical distribution that can be explained starting from a different observable function for which Nicolis et al. [2006] have found analytical results.Comment: 34 pages, 7 figures; Journal of Statistical Physics 201

Jordan-Wigner approach to dynamic correlations in spin-ladders

We present a method for studying the excitations of low-dimensional quantum spin systems based on the Jordan-Wigner transformation. Using an extended RPA-scheme we calculate the correlation function of neighboring spin flips which well approximates the optical conductivity of ${\rm Sr_2CuO_3}$. We extend this approach to the two-leg $S=1/2$--ladder by numbering the spin operators in a meander-like sequence. We obtain good agreement with the optical conductivity of the spin ladder compound (La,Ca)$_{14}$Cu$_{24}$O$_{41}$ for polarization along the rungs. For polarization along the legs higher order correlations are important to explain the weight of high-energy continuum excitations and we estimate the contribution of 4-- and 6--fermion processes.Comment: 15 pages, 16 figure

Soil biochemistry and microbial activity in vineyards under conventional and organic management at Northeast Brazil.

The São Francisco Submedium Valley is located at the Brazilian semiarid region and is an important center for irrigated fruit growing. This region is responsible for 97% of the national exportation of table grapes, including seedless grapes. Based on the fact that orgThe São Francisco Submedium Valley is located at the Brazilian semiarid region and is an important center for irrigated fruit growing. This region is responsible for 97% of the national exportation of table grapes, including seedless grapes. Based on the fact that organic fertilization can improve soil quality, we compared the effects of conventional and organic soil management on microbial activity and mycorrhization of seedless grape crops. We measured glomerospores number, most probable number (MPN) of propagules, richness of arbuscular mycorrhizal fungi (AMF) species, AMF root colonization, EE-BRSP production, carbon microbial biomass (C-MB), microbial respiration, fluorescein diacetate hydrolytic activity (FDA) and metabolic coefficient (qCO2). The organic management led to an increase in all variables with the exception of EE-BRSP and qCO2. Mycorrhizal colonization increased from 4.7% in conventional crops to 15.9% in organic crops. Spore number ranged from 4.1 to 12.4 per 50 g-1 soil in both management systems. The most probable number of AMF propagules increased from 79 cm-3 soil in the conventional system to 110 cm-3 soil in the organic system. Microbial carbon, CO2 emission, and FDA activity were increased by 100 to 200% in the organic crop. Thirteen species of AMF were identified, the majority in the organic cultivation system. Acaulospora excavata, Entrophospora infrequens, Glomus sp.3 and Scutellospora sp. were found only in the organically managed crop. S. gregaria was found only in the conventional crop. Organically managed vineyards increased mycorrhization and general soil microbial activity

Multimessenger astronomy with the Einstein Telescope

Gravitational waves (GWs) are expected to play a crucial role in the development of multimessenger astrophysics. The combination of GW observations with other astrophysical triggers, such as from gamma-ray and X-ray satellites, optical/radio telescopes, and neutrino detectors allows us to decipher science that would otherwise be inaccessible. In this paper, we provide a broad review from the multimessenger perspective of the science reach offered by the third generation interferometric GW detectors and by the Einstein Telescope (ET) in particular. We focus on cosmic transients, and base our estimates on the results obtained by ET's predecessors GEO, LIGO, and Virgo.Comment: 26 pages. 3 figures. Special issue of GRG on the Einstein Telescope. Minor corrections include

ΑΓΕΛΑΔΙΝΟ ΠΡΩΤΟΓΑΛΑ ΒΕΛΤΙΩΝΕΙ ΤΗΝ ΟΣΤΙΚΗ ΜΙΚΡΟΔΟΜΗ ΤΩΝ ΑΡΟΥΡΑΙΩΝ ΜΕ ΩΟΘΗΚΕΚΤΟΜΗ ΚΑΙ ΟΡΧΕΚΤΟΜΗ

Το αγελαδινό πρωτόγαλα ενισχύει τον αναβολισμό των οστών, ωστόσο ο ακριβής μηχανισμός δεν είναι γνωστός. Σκοπός μελέτης: Η εκτίμηση της επίδρασης διαφορετικών δόσεων πρωτογάλακτος σε αρουραίους με ωοθηκεκτομή και ορχεκτομή και ο προσδιορισμός του μηχανισμού επίδρασής του στα οστά. Αγελαδινό πρωτόγαλα χορηγήθηκε σε θηλυκούς (n=32) και αρσενικούς (n=32) αρουραίους που τυχαιοποιήθηκαν στις α) ομάδα ελέγχου (ΟΕ), β) ομάδα 1 (Ο1) (θηλυκοί=0.5 gr/μέρα, αρσενικοί=1.0 gr/μέρα), γ) ομάδα 2 (Ο2) (θηλυκοί=1 gr/μέρα, αρσενικοί= 1.5 gr/μέρα) και δ) ομάδα 3 (Ο3) (θηλυκοί=1.5 gr/μέρα, αρσενικοί= 2.0 gr/μέρα). Η οστική μικροαρχιτεκτονική και η γονιδιακή έκφραση του παράγοντα VEGF-A, μετρήθηκαν πριν και μετά από 4μηνη χορήγηση. Στους αρσενικούς αρουραίους της Ο1, η πορώδης σύσταση του φλοιού και το μέγεθος των πόρων μειώθηκαν (41.9% και 25.7% αντίστοιχα, p<0.05) σε σχέση με την ΟΕ, ενώ παρατηρήθηκε αύξηση του φλοιώδους όγκου και πυκνότητας (89.7% και 134.9% αντίστοιχα, p<0.01) και του δοκιδωτού πάχους, όγκου και πυκνότητας (37.3%, 24.6% και 7.5% αντίστοιχα, p<0.01) μετά τη χορήγηση. Στην Ο2 παρατηρήθηκαν παρόμοια αποτελέσματα, ενώ το δοκιδωτό πορώδες μειώθηκε (8.1%, p<0.01). Στην Ο3 μειώθηκε ο δοκιδωτός διαχωρισμός (29.3%, p<0.05). Στους θηλυκούς αρουραίους της Ο1 δεν παρατηρήθηκαν αλλαγές μετά τη χορήγηση, ωστόσο στις Ο2 και Ο3 μειώθηκε η σύσταση του πορώδους φλοιού (ΟΕ= 65.75±4.22. Ο2= 25.16±8.83. Ο3=25.22±8.54%, p<0.01) και βελτιώθηκε το δοκιδωτό πάχος (ΟΕ=12.22±0.99; Ο2=21.11±3.28; Ο3=18.39±2.45 μm, p<0.01). επίσης, στην Ο3 παρουσιάστηκε αύξηση της γονιδιακής έκφρασης του VEGFA (2.37±1.83, p<0.05). Το αγελαδινό πρωτόγαλα διατηρεί την οστική μάζα των αρουραίων με ωοθηκεκτομή και ορχεκτομή, ενισχύοντας τον οστικό σχηματισμό. Ο παράγοντας VEGF-A φαίνεται να παίζει σημαντικό ρόλο στη διαδικασία