Germline PTEN genotype-dependent phenotypic divergence during the early neural developmental process of forebrain organoids.

PTEN germline mutations account for ~0.2-1% of all autism spectrum disorder (ASD) cases, as well as ~17% of ASD patients with macrocephaly, making it one of the top ASD-associated risk genes. Individuals with germline PTEN mutations receive the molecular diagnosis of PTEN Hamartoma Tumor Syndrome (PHTS), an inherited cancer predisposition syndrome, about 20-23% of whom are diagnosed with ASD. We generated forebrain organoid cultures from gene-edited isogenic human induced pluripotent stem cells (hiPSCs) harboring a PTENG132D (ASD) or PTENM134R (cancer) mutant allele to model how these mutations interrupt neurodevelopmental processes. Here, we show that the PTENG132D allele disrupts early neuroectoderm formation during the first several days of organoid generation, and results in deficient electrophysiology. While organoids generated from PTENM134R hiPSCs remained morphologically similar to wild-type organoids during this early stage in development, we observed disrupted neuronal differentiation, radial glia positioning, and cortical layering in both PTEN-mutant organoids at the later stage of 72+ days of development. Perifosine, an AKT inhibitor, reduced over-activated AKT and partially corrected the abnormalities in cellular organization observed in PTENG132D organoids. Single cell RNAseq analyses on early-stage organoids revealed that genes related to neural cell fate were decreased in PTENG132D mutant organoids, and AKT inhibition was capable of upregulating gene signatures related to neuronal cell fate and CNS maturation pathways. These findings demonstrate that different PTEN missense mutations can have a profound impact on neurodevelopment at diverse stages which in turn may predispose PHTS individuals to ASD. Further study will shed light on ways to mitigate pathological impact of PTEN mutants on neurodevelopment by stage-specific manipulation of downstream PTEN signaling components.

[Cardiovascular complications in COVID-19 patients admitted to intensive care units in Chilean hospitals]. / Complicaciones cardiovasculares en pacientes COVID-19 hospitalizados en Unidades de Pacientes Críticos en Chile. Registro COVICAR.

BACKGROUND: Patients with a cardiovascular (CV) history may be at greater risk of becoming ill and die due to SARS-CoV-2. AIM: To assess the incidence of CV complications in COVID-19 patients, the type of complication, and their association with CV history. MATERIAL AND METHODS: The clinical course of 1,314 patients with COVID-19 admitted consecutively to critical care units of 10 Chilean hospitals was registered between April and August of 2020. RESULTS: The median age of patients was 59 years and 66% were men. One hundred-four (8%) had a CV history, namely heart failure (HF) in 53 (4.1%), coronary heart disease in 50 (3.8 %), and atrial fibrillation in 36 (2.7 %). There were CV complications in 359 patients (27.3%). The most common were venous thrombosis in 10.7% and arrhythmias in 10.5%, HF in 7.2%, type 2 acute myocardial infarction in 4.2%, arterial thrombosis in 2.0% and acute coronary syndrome (ACS) in 1.6%. When adjusted by age, sex and risk factors, only HF (Odds ratio (OR) = 7.16; 95% confidence intervals (CI), 3.96-12.92) and ACS (OR = 5.44; 95% CI, 1.50-19.82) were significantly associated with CV history. There was no association with arrhythmias, type 2 acute myocardial infarction, arterial or venous thrombosis. CONCLUSIONS: Patients with a history of CV disease are at greater risk of suffering HF and ACS when hospitalized due to COVID-19. Arrhythmias, type 2 AMI, and arterial or venous thrombosis occur with the same frequency in patients with or without CV history, suggesting that these complications depend on inflammatory phenomena related to the infection.

Aerobic Oxidations of Light Alkanes over Solid Metal Oxide Catalysts.

Heterogeneous metal oxide catalysts are widely studied for the aerobic oxidations of C1-C4 alkanes to form olefins and oxygenates. In this review, we outline the properties of supported metal oxides, mixed-metal oxides, and zeolites and detail their most common applications as catalysts for partial oxidations of light alkanes. By doing this we establish similarities between different classes of metal oxides and identify common themes in reaction mechanisms and research strategies for catalyst improvement. For example, almost all partial alkane oxidations, regardless of the metal oxide, follow Mars-van Krevelen reaction kinetics, which utilize lattice oxygen atoms to reoxidize the reduced metal centers while the gaseous O2 reactant replenishes these lattice oxygen vacancies. Many of the most-promising metal oxide catalysts include V5+ surface species as a necessary constituent to convert the alkane. Transformations involving sequential oxidation steps (i.e., propane to acrylic acid) require specific reaction sites for each oxidation step and benefit from site isolation provided by spectator species. These themes, and others, are discussed in the text.

Why Boron Nitride is such a Selective Catalyst for the Oxidative Dehydrogenation of Propane.

Boron-containing materials, and in particular boron nitride, have recently been identified as highly selective catalysts for the oxidative dehydrogenation of alkanes such as propane. To date, no mechanism exists that can explain both the unprecedented selectivity, the observed surface oxyfunctionalization, and the peculiar kinetic features of this reaction. We combine catalytic activity measurements with quantum chemical calculations to put forward a bold new hypothesis. We argue that the remarkable product distribution can be rationalized by a combination of surface-mediated formation of radicals over metastable sites, and their sequential propagation in the gas phase. Based on known radical propagation steps, we quantitatively describe the oxygen pressure-dependent relative formation of the main product propylene and by-product ethylene. Free radical intermediates most likely differentiate this catalytic system from less selective vanadium-based catalysts.

Probing the Transformation of Boron Nitride Catalysts under Oxidative Dehydrogenation Conditions.

Hexagonal boron nitride (h-BN) and boron nitride nanotubes (BNNT) were recently reported as highly selective catalysts for the oxidative dehydrogenation (ODH) of alkanes to olefins in the gas phase. Previous studies revealed a substantial increase in surface oxygen content after exposure to ODH conditions (heating to ca. 500 °C under a flow of alkane and oxygen); however, the complexity of these materials has thus far precluded an in-depth understanding of the oxygenated surface species. In this contribution, we combine advanced NMR spectroscopy experiments with scanning electron microscopy and soft X-ray absorption spectroscopy to characterize the molecular structure of the oxygen functionalized phase that arises on h-BN and BNNT following catalytic testing for ODH of propane. The pristine BN materials are readily oxidized and hydrolyzed under ODH reaction conditions to yield a phase consisting of three-coordinate boron sites with variable numbers of hydroxyl and bridging oxide groups which is denoted B(OH) xO3- x (where x = 0-3). Evidence for this robust oxide phase revises previous literature hypotheses of hydroxylated BN edges as the active component on h-BN.

Serendipity in Catalysis Research: Boron-Based Materials for Alkane Oxidative Dehydrogenation.

Light olefins such as ethylene and propylene form the foundation of the modern chemical industry, with yearly production volumes well into the hundreds of millions of metric tons. Currently, these light olefins are mainly produced via energy-intensive steam cracking. Alternatively, oxidative dehydrogenation (ODH) of light alkanes to produce olefins allows for lower operation temperatures and extended catalyst lifetimes, potentially leading to valuable process efficiencies. The potential benefits of this route have led to significant research interest due to the wide availability of natural gas from shale deposits. Advances in this area have still not yielded catalysts that are sufficiently selective to olefins for industrial implementation, and ODH still remains a holy grail of selective alkane oxidation research. The main challenge in selective oxidation lies in preventing the overoxidation of the desired product, such as propylene during propane oxidation, to CO and CO2. Research into selective heterogeneous catalysts for the oxidative dehydrogenation of propane has led to the extensive use of vanadium oxide-based catalysts, and studies on the surface mechanism involved have been used to improve the catalytic activity of the material. Despite decades of research, however, selectivity toward propylene has not proven satisfactory at industrially relevant conversions. It is imperative for new catalytic systems that minimize product overoxidation to be developed for future applications of oxidative dehydrogenation processes. While rational catalyst design has been successful in developing homogeneous catalyst systems, its practical use in heterogeneous catalyst development remains modest. The complexity of surfaces with a variety of terminations and bulk structures, let alone their modification by the chemical potential of a reaction mixture, makes heterogeneous catalyst discovery serendipitous in many cases. The catalyst family presented in this Account is no exception. The importance of catalysis research lies in exploring the science behind serendipity. In this Account, we will first present our initial discovery of boron nitride (BN) as an unexpected catalyst for the oxidative dehydrogenation of light alkanes. Beyond its surprising activity, BN also drew interest due to its low selectivity to carbon oxides. This observation made BN distinct from previously studied metal oxide catalysts for selective alkane oxidation. We narrowed down its unique reactivity to the oxygen functionalization of the catalyst surface, particularly the formation of B-O species as probed by various spectroscopic techniques. In investigating the critical role of each of the structural elements during ODH, we discovered that not only BN but an entire class of boron-containing compounds are active and selective for the formation of propylene from propane. All these materials form a complex oxidized surface with a distribution of BO x surface sites. This discovery opens the doors to a new field of boron-based oxidation chemistry that currently has more questions than answers. We aim to make this Account a starting point for the research community to explore these new materials to understand their surface mechanisms and the surface species that offer a unique selectivity toward olefinic products. Effective use of these materials may lead to novel processes for efficient use of abundant light alkane resources by oxidation chemistry.

A PCR-RFLP assay for discrimination of Echinococcus granulosus sensu stricto and Taenia spp. in dogs stool.

In order to develop a method of identification and discrimination of Echinococcus granulosus sensu stricto from faecal samples of dogs infected with taeniid eggs (Echinococcus spp., Taenia spp.), a combined strategy of Polymerase Chain Reaction (PCR) and Restriction Fragments of Lenght Polymorphisms (RFLP) was proposed. Initially, a pair of primers was designed to amplify a fragment of the 12 Subunit of ribosomal RNA gene (12SrRNA) from mitochondrial DNA. The amplified product was digested by SspI restriction enzyme, which in E. granulosus kept the intact fragment of 160 basis pairs (bp), while in Taenia spp. produced two fragments (62 bp and another of 98 bp). The method was tested using positive controls of DNA, in faecal samples experimentally contaminated with eggs of E. granulosus and Taenia spp. and in dogs naturally infected. In all of them, reproducible results were obtained and the primers were specific to amplify only Taeniidae DNA. The sensitivity of the technique was tested, achieving amplification of DNA extractions with a single egg. In conclusion, the technique developed was optimal and easy to identify patent infections by E. granulosus s.s., constituting a possible alternative for epidemiological studies in dogs, especially in endemic areas where this infection occurs.

Molecular Characterization of the cry Gene profile of Bacillus thuringiensis Isolated from a Caribbean Region of Colombia.

In order to characterize native strains of Bacillus thuringiensis of the Colombian Caribbean with toxic effect against insect vectors, 28 samples of bacteria identified as B. thuringiensis were isolated from different soils and muds around the city of Valledupar. Using a biological test, five isolates of B. thuringiensis showed toxic effect against larvae of Aedes aegypti. PCR methods were used to detect cry1, cry2, cry4B, cry10 and cyt1 genes. Cry1 and cry2 genes were detected in 35.7% and 32.1% of the 28 isolates analyzed, respectively. Surprisingly, reduced lengths of cry4B gene segments were detected in 28.6% of B. thuringiensis samples. The presence of cry10 or cyt1 was not detected in any of the 28 samples of B. thuringiensis, despite the high sensitivity of the assays used. The results show that B. thuringiensis samples from the Colombian Caribbean have atypical characteristics compared to those of Latin America and elsewhere in the world, which is consistent with the idea that the geographic origin of B. thuringiensis samples is associated with their biological and genetic characteristics.

Expression, purification, and biochemical characterization of recombinant DNA polymerase beta of the Trypanosoma cruzi TcI lineage: requirement of additional factors and detection of phosphorylation of the native form.

Chagas disease, caused by the protozoan Trypanosoma cruzi, is a major parasitic disease that affects millions of people in America. However, despite the high impact of this disease on human health, no effective and safe treatment has been found that eliminates the infecting parasite from human patients. Among the possible chemotherapeutic targets that could be considered for study in T. cruzi are the DNA polymerases, in particular DNA polymerase beta (polß), which previous studies have shown to be involved in kinetoplast DNA replication and repair. In this paper, we describe the expression, purification, and biochemical characterization of the Miranda clone polß, corresponding to lineage T. cruzi I (TcI). The recombinant enzyme purified to homogeneity displayed specific activity in the range described for a highly purified mammalian polß. However, the trypanosome enzyme exhibited important differences in biochemical properties compared to the mammalian enzymes, specifically an almost absolute dependency on KCl, high sensitivity to N-ethylmaleimide (NEM), and low sensitivity to ddTTP. Immuno-affinity purification of T. cruzi polymerase beta (Tcpolß) from epimastigote extracts showed that the native enzyme was phosphorylated. In addition, it was demonstrated that Tcpolß interacts with some proteins in a group of about 15 proteins which are required to repair 1-6 bases of gaps of a double strand damaged DNA. It is possible that these proteins form part of a DNA repair complex, analogous to that described in mammals and some trypanosomatids.

Detection of the G3 genotype of Echinococcus granulosus from hydatid cysts of Chilean cattle using COX1 and ND1 mitochondrial markers.

For a deeper understanding of the phylogenetic relationships of Echinococcus genotypes and species in different intermediate hosts, we analyzed samples from human and bovine hydatid cysts. For this, segments of the cytochrome oxidase (COX1) and NADH dehydrogenase (ND1) mitochondrial genes were used. To obtain sufficient amounts of the ND1 marker to be sequenced properly, a new variant of the PCR assay was implemented. Phylogenetic analysis with both markers showed that most of the analyzed samples correspond to genotype G1. However, a sample from cysts of a bovine lung (Q21), with the COX1 marker, was grouped in a node together with a sample belonging to genotype G3. In the phylogenetic tree obtained with the ND1 marker, this sample was grouped with sequences of genotypes G3, G2, and G4. Analyzing the single nucleotide polymorphic (SNP) sites of both markers, it was observed that the Q21 sequence is almost identical to the G3 sequence and differ in only one SNP from the G2 sequence, and is completely different from G4. These results are noteworthy, since neither G2 nor G3 genotypes have been described previously in Chile, raising the possibility that the G3 genotype is present in these latitudes. This information is highly relevant; it can be employed to uncover additional unknown details of transmission cycles of this important parasite.

[Estimation of costs caused by cystic echinococcosis]. / Estimación del impacto económico de la equinococosis quística en Chile y análisis de las posibles causas que han dificultado su erradicación.

BACKGROUND: Hydatid disease or cystic echinococcosis, caused by the parasite Echinococcus granulosus, has a worldwide distribution, affecting people of working age and can cause high levels of morbidity and even death. AIM: To estimate the economic impact at the human and animal level caused by the disease in Chile. MATERIAL AND METHODS: We analyzed information about the disease obtained from reports and publications emanated from the Chilean Ministry of Health, United Nations Food and Agriculture Organization, the U.S. National Institute of Statistics and the National Agricultural Service. Animal derived costs were estimated evaluating the expenses for pharmacological treatment of infected dogs and animal production losses derived from confiscations and reductions in meat production. RESULTS: The total number of patients who underwent surgery to remove a hydatid cyst in Chile during 2012, was estimated as 767 individuals. The annual costs derived only from surgical treatment, were estimated in USD 2.46 million. Summing the costs of sick leaves and loss of productivity, the costs at the human level ascended to USD 3.13 million. Considering human and animal costs, the annual economic burden of the disease was estimated in USD 14.35 million. CONCLUSIONS: The Analysis of the regional distribution of human and animal hydatidosis, suggests a significant environmental contamination with parasite eggs in high incidence regions such as Aysén, Araucanía, BioBío and Coquimbo. The efficiency of control programs for the disease would be greatly improved if the causes for these regional contaminations are elucidated.

[Transcatheter aortic valve implantation: experience in 17 patients]. / Implante valvular aórtico transarterial: experiencia en Chile.

BACKGROUND: Transcatheter aortic valve implantation (TAVI) is taking a leading role in the management of patients with severe aortic stenosis. Valve replacement surgery prolongs survival and is the technique of choice considering its historical background and long experience worldwide. Recently however, TAVI has positioned itself as the only standard therapy for symptomatic patients who are not candidates for surgery. AIM: To report the experience with this new technique comparing our results with those reported in the literature. MATERIAL AND METHODS: Between May 2010 and December 2011,17 patients aged 81 ± 7.3 years (58.8% men with an Euro SCORE 29 ± 22.4%) underwent a TAVI. RESULTS: The median transvalvular gradient was 54 ± 15.7 mmHg. All patients received a CoreValve™. Technical success was 100%, with a post implant gradient of 6.29 ± 3.3 mmHg. Residual aortic regurgitation was observed in 94%, none greater than grade II. There were no complications at the vascular access site. One patient developed cardiac tamponade during the procedure. Permanent pacemaker implantation was required in 35.2%. Hospital mortality rate was 5.8%, a figure that remained unchanged at 30 days of follow-up. CONCLUSIONS: In high-risk patients with aortic stenosis, TAVI has a high success rate and a low rate of complications. Besides an appropriate patient selection, a trained multidisciplinary team and technical conditions to solve possible complications of the procedure are required.

Differential cell cycle checkpoint evasion by PTEN germline mutations associated with dichotomous phenotypes of cancer versus autism spectrum disorder.

Individuals with a PTEN germline mutation receive the molecular diagnosis of PTEN hamartoma tumor syndrome (PHTS). PHTS displays a complex spectrum of clinical phenotypes including harmartomas, predisposition to cancers, and autism spectrum disorder (ASD). Clear-cut genotype-phenotype correlations are yet to be established due to insufficient information on the PTEN function being impacted by mutations. To fill this knowledge gap, we compared functional impacts of two selected missense PTEN mutant alleles, G132D and M134R, each respectively being associated with distinct clinical phenotype, ASD or thyroid cancer without ASD using gene-edited human induced pluripotent stem cells (hiPSCs). In homozygous hiPSCs, PTEN expression was severely reduced by M134R mutation due to shortened protein half-life. G132D suppressed PTEN expression to a lesser extent than Μ134R mutation without altering protein half-life. When challenged with γ-irradiation, G132D heterozygous cells exited radiation-induced G2 arrest earlier than wildtype and M134R heterozygous hiPSCs despite the similar DNA damage levels as the latter two. Immunoblotting analyses suggested that γ-irradiation induced apoptosis in G132D heterozygous cells to lesser degrees than in the hiPSCs of other genotypes. These data suggest that ASD-associated G132D allele promotes genome instability by premature cell cycle reentry with incomplete DNA repair.

Basal Forebrain Modulation of Olfactory Coding In Vivo.

Sensory perception is one of the most fundamental brain functions, allowing individuals to properly interact and adapt to a constantly changing environment. This process requires the integration of bottom-up and topdown neuronal activity, which is centrally mediated by the basal forebrain, a brain region that has been linked to a series of cognitive processes such as attention and alertness. Here, we review the latest research using optogenetic approaches in rodents and in vivo electrophysiological recordings that are shedding light on the role of this region, in regulating olfactory processing and decisionmaking. Moreover, we summarize evidence highlighting the anatomical and physiological differences in the basal forebrain of individuals with autism spectrum disorder, which could underpin the sensory perception abnormalities they exhibit, and propose this research line as a potential opportunity to understand the neurobiological basis of this disorder.

La percepción sensorial es una de las funciones cerebrales más fundamentales, permitiendo a los individuos interactuar de manera apropiada con el entorno y adaptarse a un ambiente en constante cambio. Este proceso requiere la integración de la actividad neuronal ascendente y descendente, que es mediada por el cerebro basal (BF), una región cerebral que ha sido asociada a una serie de procesos cognitivos, como estados de atención y alerta.En este trabajo revisamos las últimas investigaciones que han utilizado optogenética y registros electrofisiológicos in vivo que han iluminado el rol del BF en el procesamiento olfatorio y la toma de decisiones. Además, resumimos la literatura que destaca las alteraciones fisiológicas y anatómicas del BF de individuos con trastornos del espectro autista, que podrían subyacer las anormalidades en la percepción que presentan, y proponemos esta línea de investigación como una posible oportunidad para entender las bases neurobiológicas de este trastorno.

Isolation, molecular characterization and pathogenicity of native Bacillus thuringiensis, from Ethiopia, against the tomato leafminer, Tuta absoluta: Detection of a new high lethal phylogenetic group.

Tuta absoluta (tomato leafminer) is one of the devastating agricultural pest that attack mainly tomatoes. The continuous use of chemical pesticides is not affordable and poses a collateral damage to human and environmental health. This requires integrated pest management to reduce chemical pesticides. B. thuringiensis is a cosmopolitan, antagonistic soil bacterium used to control agricultural pests. In this study, effective Bt strains were screened from different sample sources based on their lepidopteran specific cry genes and larvicidal efficacy against tomato leafminer, T. absoluta under laboratory conditions. Of the 182 bacterial isolates, 55 (30 %) of isolates harbored parasporal protein crystals. Out of these, 34 (62 %) isolates possess one or more lepidopteran specific cry genes: 20 % of isolates positive for cry2, 18.2 % for cry9, 3.6 % for cry1, 16.4 % for cry2 + cry9, 1.8 % for cry1 + cry9, and 1.8 % for cry1 + cry2 + cry9. However, 21 (38.2 %) isolates did not show any lepidopteran specific cry genes. Isolates positive for cry genes showed 36.7-75 % and 46.7-98.3 % mortality against second and third instar larvae of the T. absoluta at the concentration of 108 colony forming units (CFUs) ml-1. Cry1 and cry1 plus other cry gene positive isolates were relatively more pathogenic against T. absoluta. However, third instar larvae of the T. absoluta was more susceptible than second instar larvae. Two of the isolates, AAUF6 and AAUMF9 were effective and scored LT50 values of 2.3 and 2.7 days and LC50 values of 3.4 × 103 and 4.15 × 103 CFUs ml-1 against the third instar larvae, respectively. The phylogenetic studies showed some congruence of groups with cry gene profiles and lethality level of isolates and very interestingly, we have detected a putative new phylogenetic group of Bt from Ethiopia.

Molecular phylogeny and pathogenicity of indigenous Beauveria bassiana against the tomato leafminer, Tuta absoluta Meyrick 1917 (Lepidoptera: Gelechiidae), in Ethiopia.

BACKGROUND: Tuta absoluta Meyrick 1917 (Lepidoptera: Gelechiidae) is an invasive, pesticide resistant, and a major treat of tomato production in the world. It needs effective management options that naturally infect the insect without causing any identified side effects. Entomopathogenic fungi (EPF) are the most important options. However, geographic origin and climatic condition apparently creates genetic variation among EPF strains that influence on their pathogenicity. Thus, screening of effective EPF strains from the local source is vital to develop environmental friendly pest control tactic for T. absoluta. RESULTS: In this study, 27 indigenous Beauveria were isolated from the various types of soil and 12 of the isolates were screened based on their biological efficiency index (BEI). These isolates scored 65.7-95.7% and 68.3-95% of mortality against second and third instar larvae of T. absoluta at concentration of 1 × 107spores·ml-1 in 7 days post inoculation, respectively. Out of these, five (18.5%) isolates scored above 90% mortality on both instar larvae with LT50 value of 3.33 to 5.33 days at the lowest (104 spores·ml-1) and 1.93 to 3.17 days at highest (108 spores·ml-1) spore concentrations and has LC50 value of 1.5 × 103 to 1.1× 105 spores·ml-1. Moreover, isolates exhibited the promising mortality better (1.5 × 106 to 3.5 × 107 spores·ml-1), sporulated over the larval cadavers, well grown at optimal temperature, and produced chitinolytic enzymes. Molecular analysis showed that isolates have nearly monophyletic characters and grouped under species of Beauveria bassiana. CONCLUSION: Different types of soil in Ethiopia are an important source of B. bassiana, and these isolates showed promising pathogenicity against T. absoluta, which is crucial for ecofriendly biopesticide development. Although isolates were nearly monophyletic in phylogenetic study, five of them were highly effective in the laboratory bioassays against T. absoluta; however, further field evaluation is required for mass production.

A new Colombian species of Liodessus diving beetles from the Páramo de Sumapaz (Coleoptera, Dytiscidae, Bidessini).

Liodessuspicinus sp. nov. is described from the Páramo de Sumapaz near Bogota D.C. at 3,500 m above sea level. The species can be distinguished from the other Colombian Liodessus species by its dark coloration, discontinuous habitus, shiny surface of the pronotum and elytron, presence of a distinct occipital line, distinct basal pronotal striae, short or even faint basal elytral striae, as well as by its distinct geographic distribution and cox1 signature.

Microsatellite marker analysis shows differentiation among Trypanosoma cruzi populations of peripheral blood and dejections of Triatoma infestans fed on the same chronic chagasic patients : microsatellite marker analysis and T. cruzi.

To investigate whether Trypanosoma cruzi populations found in chagasic cardiopathic and non-cardiopathic patients are genetically differentiated, three molecular microsatellite markers were analysed. This analysis was also applied to compare T. cruzi samples from peripheral blood or dejections of Triatoma infestans fed on the blood of the same patients. In order to obtain the first objective, analyses of predominant T. cruzi genotypes were conducted using three approaches: a locus-by-locus analysis; a Fisher method across three loci; and analysis of molecular variance by Genepop and Arlequin programs. Only with one locus and on the blood samples was a significant differentiation detected among non-cardiopathic and cardiopathic groups, which was not confirmed by the other two methods. On the contrary, with the three approaches, it was found that T. cruzi clones present in the blood of patients are genetically differentiated from those detected in dejections of T. infestans fed on the same patients. Our results showed that the most frequent lineage both in blood as well as in triatomine dejection samples was TcI. No significant difference in T. cruzi lineage distribution was observed among chagasic cardiopathic and non-cardiopathic patients. The majority of the samples (50-60%) had only one T. cruzi clone (uniclonal) either in blood or dejection samples.

Selective Oxidative Cracking of n-Butane to Light Olefins over Hexagonal Boron Nitride with Limited Formation of COx.

In recent years, hexagonal boron nitride (hBN) has emerged as an unexpected catalyst for the oxidative dehydrogenation of alkanes. Here, the versatility of hBN was extended to alkane oxidative cracking chemistry by investigating the production of ethylene and propylene from n-butane. Cracking selectivity was primarily controlled by the ratio of n-butane to O2 within the reactant feed. Under O2 -lean conditions, increasing temperature led to increased selectivity to ethylene and propylene and decreased selectivity to COx . In addition to surface-mediated chemistry, homogeneous gas-phase reactions likely contributed to the observed product distribution, and a reaction mechanism was proposed based on these observations. The catalyst showed good stability under oxidative cracking conditions for 100 h time-on-stream while maintaining high selectivity to ethylene and propylene.

Phylogenetic analysis of microsatellite markers further supports the two hybridization events hypothesis as the origin of the Trypanosoma cruzi lineages.

To better understand the evolution of the etiologic agent of Chagas disease, we cloned and sequenced 25 alleles from five Tripanosoma cruzi microsatellite markers. The study of the sequences showed highly conserved alleles present in T. cruzi clones belonging to TCI, TCIIc, and TCIIe. This result was also confirmed by the phylogenetic analysis of MCLE01 allele sequences. The examination by capillary electrophoresis of six microsatellite markers from 19 T. cruzi clones showed a high proportion of the alleles found both in the TCI and TCII sublineages. The phylogenetic reconstruction of these 19 clones produced a tree with two major clusters with bootstrap support of 100% and 95%. The first cluster includes T. cruzi clones belonging to the TCI and TCIIa lineages. The second cluster is composed of TCI, TCIIc, TCIId, and TCIIe T. cruzi clones. The analysis of five microsatellite markers in the CLBrener genome showed that almost all the microsatellite markers are synteny; non-Esmeraldo and Esmeraldo haplotypes probably come from the TCIIc and TCIIb lineages. Taken together, our results are in agreement with the two hybridization events hypothesis as the origin of current T. cruzi lineages.