Inefficient Complement System Clearance of Trypanosoma cruzi Metacyclic Trypomastigotes Enables Resistant Strains to Invade Eukaryotic Cells

The complement system is the main arm of the vertebrate innate immune system against pathogen infection. For the protozoan Trypanosoma cruzi, the causative agent of Chagas disease, subverting the complement system and invading the host cells is crucial to succeed in infection. However, little attention has focused on whether the complement system can effectively control T. cruzi infection. To address this question, we decided to analyse: 1) which complement pathways are activated by T. cruzi using strains isolated from different hosts, 2) the capacity of these strains to resist the complement-mediated killing at nearly physiological conditions, and 3) whether the complement system could limit or control T. cruzi invasion of eukaryotic cells. The complement activating molecules C1q, C3, mannan-binding lectin and ficolins bound to all strains analysed; however, C3b and C4b deposition assays revealed that T. cruzi activates mainly the lectin and alternative complement pathways in non-immune human serum. Strikingly, we detected that metacyclic trypomastigotes of some T. cruzi strains were highly susceptible to complement-mediated killing in non-immune serum, while other strains were resistant. Furthermore, the rate of parasite invasion in eukaryotic cells was decreased by non-immune serum. Altogether, these results establish that the complement system recognizes T. cruzi metacyclic trypomastigotes, resulting in killing of susceptible strains. The complement system, therefore, acts as a physiological barrier which resistant strains have to evade for successful host infection

Complement C2 Receptor Inhibitor Trispanning Confers an Increased Ability to Resist Complement-Mediated Lysis in Trypanosoma cruzi

The ability to resist complement differs between theYand Colombiana Trypanosoma cruzi strains.Wefound that the Y strain of T. cruzi was more able to resist the classical and lectin pathways of complement activation than the Colombiana strain. The complement C2 receptor inhibitor trispanning gene (CRIT) is highly conserved in both strains. At the protein level, CRIT is expressed only in stationary-phase epimastigotes of the Y but not the Colombiana strain and is expressed in infectious metacyclic trypomastigotes of both strains. Y strain epimastigotes with an overexpressed CRIT gene (pTEX-CRIT) had higher survival in normalhumanserum (NHS). Overexpression of the Y strain CRIT gene in Colombiana epimastigote forms increased the parasite's resistance to lysis mediated by the classical and lectin pathways but not to lysis mediated by alternative pathways. CRIT involvement on the parasite surface was confirmed by showing that the lytic activity ofNHSagainst epimastigotes could be restored by adding excess C

Hematologic and hepatic responses of the freshwater fish Hoplias malabaricus after saxitoxin exposure.

The bioaccumulation of saxitoxins (STX) in the trophic chain, mainly in freshwater, are not completely known. This work aimed to elucidate the effects of STX on Hoplias malabaricus through trophic bioassay. The fish were fed once every five days with Astyanax sp. before being subjected to an intraperitoneal inoculation with the lysate of Cylindrospermopsis raciborskii culture containing 97% STX and 3% by neosaxitoxin and gonyautoxin during 20 days. The animal?s liver was assessed using biomarkers as activities of superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), and glutathione peroxidase (GPx), and concentrations of reduced glutathione (GSH) and lipoperoxidation (LPO) and protein carbonylation (PCO). In the blood was analyzed the genotoxic and hematological parameters. The hepatosomatic index and the relative condition factor did not show a significant difference between the exposed and control groups. The values of mean corpuscular hemoglobin concentration and mean corpuscular hemoglobin increased in the STX group. The hepatic tissue from both groups exhibited a typical pattern that have been already described for most teleost fish. The results suggested the generation of reactive oxygen species, with increased activity of GPx and concentrations of LPO and GSH; whereas the specific activity of SOD decreased. However, no changes were observed in the CAT, PCO, and DNA damage. Although the STX effects are known as neurotoxic, this cyanotoxin caused liver biochemical alterations that can be considered ecologically relevant

The Dependency of Nematic and Twist-bend Mesophase Formation on Bend Angle

We have prepared and studied a family of cyanobiphenyl dimers with varying linking groups with a view to exploring how molecular structure dictates the stability of the nematic and twist-bend nematic mesophases. Using molecular modelling and 1D (1)H NOESY NMR spectroscopy, we determine the angle between the two aromatic core units for each dimer and find a strong dependency of the stability of both the nematic and twist-bend mesophases upon this angle, thereby satisfying earlier theoretical models

Conformational landscapes of bimesogenic compounds and their implications for the formation of modulated nematic phases

The twist-bend phase (NTB) is most commonly observed in materials with a gross-bent shape: dimers; bent-cores; bent-oligomers. We had suggested previously that the bend-angle of such systems effectively dictates the relative thermal stability of the NTB phase. However, our earlier paper relied on the use of a single energy-minimum conformer and so failed to capture any information about flexibility and conformational distribution. In the present work, we revisit our hypothesis and examine a second set of dimers with varying linking groups and spacer composition. We have improved on our earlier work by studying the conformational landscape of each material, allowing average bend-angles to be determined as well as the conformer distribution. We observe that the stability of the NTB phase exhibits a strong dependence not only on the Boltzmann-weighted average bend-angle (rather than just a static conformer), but also on the distribution of conformers. To a lesser extent, the flexibility of the spacer appears important. Ultimately, this work satisfies both theoretical treatments and our initial experimental study and demonstrates the importance of molecular bend to the NTB phase

Genome of the Avirulent Human-Infective Trypanosome—Trypanosoma rangeli

Background: Trypanosoma rangeli is a hemoflagellate protozoan parasite infecting humans and other wild and domestic mammals across Central and South America. It does not cause human disease, but it can be mistaken for the etiologic agent of Chagas disease, Trypanosoma cruzi. We have sequenced the T. rangeli genome to provide new tools for elucidating the distinct and intriguing biology of this species and the key pathways related to interaction with its arthropod and mammalian hosts.  Methodology/Principal Findings: The T. rangeli haploid genome is ,24 Mb in length, and is the smallest and least repetitive trypanosomatid genome sequenced thus far. This parasite genome has shorter subtelomeric sequences compared to those of T. cruzi and T. brucei; displays intraspecific karyotype variability and lacks minichromosomes. Of the predicted 7,613 protein coding sequences, functional annotations could be determined for 2,415, while 5,043 are hypothetical proteins, some with evidence of protein expression. 7,101 genes (93%) are shared with other trypanosomatids that infect humans. An ortholog of the dcl2 gene involved in the T. brucei RNAi pathway was found in T. rangeli, but the RNAi machinery is non-functional since the other genes in this pathway are pseudogenized. T. rangeli is highly susceptible to oxidative stress, a phenotype that may be explained by a smaller number of anti-oxidant defense enzymes and heatshock proteins.  Conclusions/Significance: Phylogenetic comparison of nuclear and mitochondrial genes indicates that T. rangeli and T. cruzi are equidistant from T. brucei. In addition to revealing new aspects of trypanosome co-evolution within the vertebrate and invertebrate hosts, comparative genomic analysis with pathogenic trypanosomatids provides valuable new information that can be further explored with the aim of developing better diagnostic tools and/or therapeutic targets

LIMPRINT in specialist lymphedema services in United Kingdom, France, Italy and Turkey

Background: There is no standardized international model for specialist lymphoedema services, which covers the types of lymphoedema treated and the treatments provided. The aim of this study was to provide a profile of patients attending specialist lymphoedema services in different countries to explore similarities and differences. Methods and Results: The LIMPRINT core tool was used in specialist lymphoedema services in the UK, France, Italy and Turkey. Services in Turkey saw a slightly younger age group with a higher proportion of female patients reflecting a particular focus on breast cancer-related lymphoedema. There were higher levels of obesity and restricted mobility in patients in the UK compared with other countries. Italy and France saw the highest percentage of patients with primary lymphoedema. Diabetes was a common comorbidity in the UK and Turkey. The UK saw the largest number of patients with lower limb lymphoedema. Conclusions: The results show a wide range of complexity of patients treated in specialist lymphoedema services. Some of the differences between countries may reflect different stages in the evolution of specialist lymphoedema services, rather than a true difference in prevalence, with those with 'younger' services treating a high proportion of patients with cancer and those with more established services treating a wider range of different types of lymphoedema including more elderly people with multiple comorbidities

Combined Microscopy, Calorimetry and X-ray Scattering Study of Fluorinated Dimesogens

The material FDO11DFCB3 (compound 2 in this work) remains the only example of a liquid-crystalline material to exhibit a phase transition from the heliconical twist-bend phase into a lamellar smectic A mesophase, additionally this material exhibits a previously unidentified mesophase. We have prepared and characterised several homologues of this compound, with each material subjected to an in-depth analysis by optical microscopy, calorimetry and small angle X-ray scattering studies. Despite FDO11DFCB3 being similar in chemical structure to the novel materials presented herein its liquid-crystalline behaviour is rather different, indicating an unexpected sensitivity of the twist-bend phase to molecular structure