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).

<Emphasis Type="Italic">Scenedesmus</Emphasis> sp. cultivation using commercial-grade ammonium sources

The use of commercial-grade nutrients such as agricultural fertilizers is important for commercial microalgae cultivation, and this is particularly the case for biofuel production which is associated with low added value. Nitrogen is a very important macronutrient in microalgae cultivation, and ammonium sources are cheaper than nitrate sources. However, the growth response and cellular composition can be altered by the different nutrient sources. In the study reported here, we investigated the effects of different ammonium doses and commercial-grade macronutrients from agricultural fertilizers on the growth of Scenedesmus sp. BR003, a promising genus for biofuel production. Five growth media were developed using fertilizers and evaluated during Scenedesmus sp. cultivation under autotrophic conditions. The growth media differed in terms of their composition and concentration of macronutrients. We found that all commercial-grade media supported equal or higher cell concentrations, dry weight, water-soluble proteins, neutral carbohydrates, and total lipid production compared to the conventional BG11 medium. However, the commercial-grade growth medium with the highest ammonium content affected the coenobium pattern of Scenedesmus sp. BR003. Commercial-grade nutrient sources were a low-cost alternative to improve the growth of Scenedesmus sp. BR003. The different fertilizers also allowed for manipulation of microalgae chemical composition and phenotypic plasticity to target traits of commercial interest. Our results demonstrate the potential of using ammonium from agricultural fertilizers as a nitrogen source in combination with other commercial-grade macronutrients sources. In addition, this work demonstrates the ability of a robust Scenedesmus strain to grow in media of different compositions, even when a high dosage of ammonium was used.     

Low concentrations of glyphosate‐based herbicide cause complete loss of sperm motility of yellowtail tetra fish Astyanax lacustris

Environmental relevant concentrations of glyphosate‐based herbicide as 50 µg l^?1, 300 µg l^?1 and 1800 µg l^?1 can affect sperm quality of yellowtail tetra fish Astyanax lacustris . Viability of sperm cells was impaired at 300 µg l^?1, a concentration that is within legal limits in U.S.A. waterbodies, while motility was impaired at 50 µg l^?1, which is the more stringent limit set in Brazilian law. Therefore, environment protection agencies must review regulations of glyphosate‐based herbicides on water bodies.     

Characterization of <Emphasis Type="Italic">Capsicum annuum</Emphasis> L. leaf and root antimicrobial peptides: antimicrobial activity against phytopathogenic microorganisms

This study aimed to detect and characterize antimicrobial proteins, especially antimicrobial peptides (AMPs) from leaves and roots of Capsicum annuum and to evaluate their inhibitory activities against different phytopathogenic fungi and the bacterium Xanthomonas euvesicatoria. Two methodologies were used for the extraction of peptides from leaves and roots of C. annuum: acid and ethanolic extraction. Extracts were subjected to reversed-phase chromatography on HPLC. The extraction and purification procedures were analysed by uni- and bi-dimensional electrophoresis in tricine gels. Our results show that alcoholic and acid extracts from both tissues can inhibit the growth of the phytopathogenics fungi C. lindemuthianum and C. gloeosporioides. The acid extracts from both tissues are active against X. euvesicatoria and only leaf extracts displayed specific inhibitory activity towards trypsin and α-amylase activity. The data compiled here aim to contribute to establish the multiplicity of potential uses of plant AMPs for the control of pests and pathogens of agricultural relevance.     

Four years host–parasitoid food web: testing sampling effort on trophic levels

Incomplete sampling is a major problem affecting data quality with respect to food webs. We described a host–parasitoid food web based on data from four years of sampling, evaluated the dataset robustness of the food web, and tested the hypothesis that different trophic levels require different sampling efforts. We sampled Senegalia tenuifolia fruits at eight sampling sites in three areas, during four years (2011–2014) in the Brazilian cerrado (savanna). We recorded 26 insect species in three trophic levels associated with S. tenuifolia. For species accumulation curves, all insect trophic levels, areas and years reached the asymptote, except for one area. The cumulative species richness in each trophic level suggested that the third level (primary parasitoid) should be sampled for a longer time than the second and fourth levels, supporting our hypothesis. In conclusion, the sampling effort employed was sufficient to assess most of the insect species richness, and provided a high-quality and well-represented host-parasitoid food web, even though trophic levels require different efforts.     

A seven-coordinate Fe compound: [Fe{O(CH2CO2)2}(H2O)2(NO3)]. Preparation, structure and magnetic properties

A seven-coordinate Fe^III complex, [Fe(oda)(H₂O)₂(NO₃)], was obtained after dissolving Fe(NO₃)₃ · 9H₂O in an aqueous solution of oxydiacetic acid (H₂oda) at room temperature. In the solid state, the Fe^III center adopts a pentagonal bipyramid geometry with an {FeO₇} core formed by a tridentate oda²⁻ and a bidentate in the equatorial plane, and two axial water molecules. Magnetic measurements and EPR spectra revealed the presence of S = 5/2 Fe^III centers with rhombic zero field splitting parameters (D = 0.81 cm⁻¹, E/D = 0.33 ). Weak antiferromagnetic interactions with J ≈ −0.06 cm⁻¹ operating between neighboring Fe ions connected through Fe-O-C-O?H-O-Fe paths are estimated using the molecular field approximation.     

Binding studies of alpha-GalNAc-specific lectins to the alpha-GalNAc (Tn-antigen) form of porcine submaxillary mucin and its smaller fragments

Isothermal titration microcalorimetry (ITC) and hemagglutination inhibition measurements demonstrate that a chemically and enzymatically prepared form of porcine submaxillary mucin that possesses a molecular mass of approximately 10(6) daltons and approximately 2300 alpha-GalNAc residues (Tn-PSM) binds to the soybean agglutinin (SBA) with a K(d) of 0.2 nm, which is approximately 10(6)-fold enhanced affinity relative to GalNAcalpha1-O-Ser (Tn), the pancarcinoma carbohydrate antigen. The enzymatically derived 81 amino acid tandem repeat domain of Tn-PSM containing approximately 23 alpha-GalNAc residues binds with approximately 10(3)-fold enhanced affinity, while the enzymatically derived 38/40 amino acid cleavage product(s) of Tn-PSM containing approximately 11-12 alpha-GalNAc residues shows approximately 10(2)-fold enhanced affinity. A natural carbohydrate decorated form of PSM (Fd-PSM) containing 40% of the core 1 blood group type A tetrasaccharide, and 58% peptide-linked GalNAcalpha1-O-Ser/Thr residues, with 45% of the peptide-linked alpha-GalNAc residues linked alpha-(2,6) to N-glycolylneuraminic acid, shows approximately 10(4) enhanced affinity for SBA. Vatairea macrocarpa lectin (VML), which is also a GalNAc binding lectin, displays a similar pattern of binding to the four forms of PSM, although there are quantitative differences in its affinities as compared with SBA. The higher affinities of SBA and VML for Tn-PSM relative to Fd-PSM indicate the importance of carbohydrate composition and epitope density of mucins on their affinities for lectins. The higher affinities of SBA and VML for Tn-PSM relative to its two shorter chain analogs demonstrate that the length of a mucin polypeptide and hence total carbohydrate valence determines the affinities of the three Tn-PSM analogs. The results suggest a binding model in which lectin molecules "bind and jump" from alpha-GalNAc residue to alpha-GalNAc residue along the polypeptide chain of Tn-PSM before dissociating. The complete thermodynamic binding parameters for these mucins including their binding stoichiometries are presented. The results have important implications for the biological activities of mucins including those expressing the Tn cancer antigen.     

Floral visitors of Chamaecrista debilis (Vogel) Irwin & Barneby (Fabaceae - Caesalpinioideae) at cerrado of Estação Ecológica de Jataí, São Paulo State, Brazil

Although Chamaecrista Moench genus is a very important source of pollen to bees in the Cerrado, this relationship is almost unknown. Within flower visitors of Ch. debilis, we found hymenopterans (Apidae) as the most abundants, but Coleoptera (Buprestidae) and Lepidoptera (Noctuidae) were also collected. Bees of great size are pointed out as effective pollinators of Cassiinae. Only five out of seventeen species of floral visitors of Ch. debilis sampled in cerrado, are indicated as possible pollinators, from which four species were not previously indicated in other papers.