Zigzag graphene nanoribbon edge reconstruction with stone-wales defects

In this paper, we study zigzag graphene nanoribbons with edges reconstructed with Stone-Wales defects, by means of an empirical (first-neighbor) tight-binding method, with parameters determined by ab initio calculations of very narrow ribbons. We explore the characteristics of the electronic band structure with a focus on the nature of edge states. Edge reconstruction allows the appearance of a new type of edge states. They are dispersive, with nonzero amplitudes in both sublattices; furthermore, the amplitudes have two components that decrease with different decay lengths with the distance from the edge; at the Dirac points one of these lengths diverges, whereas the other remains finite, of the order of the lattice parameter. We trace this curious effect to the doubling of the unit cell along the edge, brought about by the edge reconstruction. In the presence of a magnetic field, the zero-energy Landau level is no longer degenerate with edge states as in the case of the pristine zigzag ribbon.Fundacao para a Ciência e a Tecnologia (FCT) SFRH/BD/44456/2008.FEDER - Programa Operacional Factores de Competitividade - COMPET

Molecular development of oxfendazole resistance starting with a susceptible Haemonchus contortus isolate.

Abstract: Haemonchus contortus is one of the main small ruminant parasites in tropical areas and its control is traditionally done through the utilization of synthetic anthelmintics such as benzimidazoles (BZ). BZ resistance is associated to single nucleotide polymorphisms (SNP) located in the Beta-tubulin isotype 1 gene: F200Y, F167Y and E198A. Here we describe the rise of resistant mutations within a completely susceptible isolate (Inbred-susceptible-Edinburgh - ISE) in an experimental infection model in 3 sheep treated with increasing oxfendazole doses. After initial infection and rise in fecal egg counts, the drug regimen started with subdoses as low as 30% of the recommended dosage and were gradually increased to 100% over the course of a year. Experimental animals were infected every 1.5 months with 5,000 L3 larvae cultured from feces collected one week after each treatment. After an initial period when resistance was only detected in the F200Y locus, both resistant polymorphisms (F200Y and F167Y) were detected in increasing frequencies after each treatment. Eventually resistance at F200Y stationed at frequencies around 70% and decreased while resistance frequencies at F167Y kept rising and finally stationed at around 75%. Resistance at E198A was never detected in the studied period. Our study provide insights into the speed as to which each polymorphism may rise as BZ dosage increases converting a susceptible parasite population into a highly resistant one within a short time period.In conjunction with 53rd MSPTM Annual Conference

Molecular diagnostic for levamisol resistance in Haemonchus contortus.

Abstract: In tropical areas, Haemonchus contortus is the leading cause of production losses in small ruminant herds and its control is traditionally done through the utilization of synthetic anthelmintics. Levamisole, an imidazothiazole derivative, is widely used in Brazil and the occurrence of resistance is not uncommon. The genetic base for levamisole resistance in H. contortus is still under investigation, but it has been recently associated with a 63 bp deletion in the Hco-acr-8 gene, which codes for one of the subunits of a levamisole-sensistive acetylcholine receptor. Here we describe a real time PCR test for the detection and quantification of the presence and absence of this deletion. Reactions contained 12.5ul 2 × Fast Start Universal SYBR Green Master Mix (Roche, West Sussex, UK), 0.3 pmol/ul of each primer (forward and reverse), 50 ng of DNA and water for a total volume of 25?l. Amplification conditions for were: 95 oC for 10 min and 35 cycles at 95 oC for 15 s and at 56 ºC for 30 s. We tested the assay in two known H. contortus isolates, one resistant (Kokstad isolate - KOK) and another susceptible (Inbred-susceptible-Edinburgh - ISE). We also used the test to characterize a local H. contortus population previously exposed to levamisole. Preliminay results are in agreement with previously reported data as only the resistant allele was detected in the KOK isolate and both alleles were detected in the ISE isolate suggesting that this test may be useful in the fast detection of levamisole resistance in H. contortus.In conjunction with 53rd MSPTM Annual Conference

Anthelmintic activity of nanoencapsulated carvacryl acetate against gastrointestinal nematodes of sheep and its toxicity in rodents.

Abstract: The objective of this study was to evaluate the efficacy of carvacryl acetate (CVA) and nanoencapsulated CVA (nCVA) on gastrointestinal nematodes of sheep. The CVA was nanoencapsulated with chitosan/gum arabic and the efficacy of nanoencapsulation (EE), yield, zeta potential, nanoparticle morphology and release kinetics at pH 3 and 8 were analyzed. Acute and subchronic toxicity were evaluated in rodents and reduction of egg counts in the faeces (FECRT) of sheep. The sheep were divided into four groups (n = 10): G1, 250 mg/kg CVA; G2, 250 mg/kg nCVA; G3, polymer matrix and G4: 2.5 mg/kg monepantel. EE and nCVA yield were 65% and 57%, respectively. The morphology of the nanoparticles was spherical, size (810.6±286.7 nm), zeta potential in pH 3.2 (+18.3 mV) and the 50% release of CVA at pHs 3 and 8 occurred at 200 and 10 h, respectively. nCVA showed LD50 of 2,609 mg/kg. CVA, nCVA and monepantel reduced the number of eggs per gram of faeces (epg) by 57.7%, 51.1% and 97.7%, respectively. The epg of sheep treated with CVA and nCVA did not differ from the negative control (P>0.05). Nanoencapsulation reduced the toxicity of CVA; however, nCVA and CVA presented similar results in the FECRT. [Atividade anti-helmíntica do acetato de carvacrila nanoencapsulado sobre nematoides gastrintestinais de ovinos e toxicidade em roedores]. Resumo: O objetivo deste trabalho foi avaliar a eficácia do acetato de carvacrila (ACV) e do ACV nanoencapsulado (nACV) sobre nematóides gastrintestinais de ovinos. O ACV foi nanoencapsulado com quitosana/goma arábica e foi analisada a eficácia de nanoencapsulamento (EE), o rendimento, potencial zeta, morfologia das nanopartículas e cinética de liberação em pH 3 e 8. Foram avaliadas as toxicidades aguda e subcrônica em roedores e a redução da contagem de ovos nas fezes (RCOF) de ovinos. Os ovinos foram divididos em quatro grupos (n = 10): G1, 250 mg/kg ACV; G2, 250 mg/kg de nACV; G3, matriz polimérica e G4: 2,5 mg/kg de monepantel. A EE e o rendimento de nACV foram de 65% e 57%, respectivamente. A morfologia das nanopartículas foi esférica, tamanho (810,6±286,7 nm), potencial zeta no pH 3,2 (+18,3 mV) e a liberação de 50% de CVA nos pHs 3 e 8 ocorreu às 200 e 10 h, respectivamente. nACV apresentou DL50 de 2.609 mg/kg. ACV, nACV e o monepantel reduziram a contagem de ovos por grama de fezes (opg) em 57,7%, 51,1% e 97,7%, respectivamente. A contagem de opg de ovelhas tratadas com ACV e nCVA não diferiu do controle negativo (P>0,05). O nanoencapsulamento reduziu a toxicidade do AVC; no entanto, nACV e ACV apresentaram resultados semelhantes na RCOF

High-resolution genetic map and QTL analysis of growth-related traits of Hevea brasiliensis cultivated under suboptimal temperature and humidity conditions

Rubber tree (Hevea brasiliensis) cultivation is the main source of natural rubber worldwide and has been extended to areas with suboptimal climates and lengthy drought periods; this transition affects growth and latex production. High-density genetic maps with reliable markers support precise mapping of quantitative trait loci (QTL), which can help reveal the complex genome of the species, provide tools to enhance molecular breeding, and shorten the breeding cycle. In this study, QTL mapping of the stem diameter, tree height, and number of whorls was performed for a full-sibling population derived from a GT1 and RRIM701 cross. A total of 225 simple sequence repeats (SSRs) and 186 single-nucleotide polymorphism (SNP) markers were used to construct a base map with 18 linkage groups and to anchor 671 SNPs from genotyping by sequencing (GBS) to produce a very dense linkage map with small intervals between loci. The final map was composed of 1,079 markers, spanned 3,779.7 cM with an average marker density of 3.5 cM, and showed collinearity between markers from previous studies. Significant variation in phenotypic characteristics was found over a 59-month evaluation period with a total of 38 QTLs being identified through a composite interval mapping method. Linkage group 4 showed the greatest number of QTLs (7), with phenotypic explained values varying from 7.67 to 14.07%. Additionally, we estimated segregation patterns, dominance, and additive effects for each QTL. A total of 53 significant effects for stem diameter were observed, and these effects were mostly related to additivity in the GT1 clone. Associating accurate genome assemblies and genetic maps represents a promising strategy for identifying the genetic basis of phenotypic traits in rubber trees. Then, further research can benefit from the QTLs identified herein, providing a better understanding of the key determinant genes associated with growth of Hevea brasiliensis under limiting water conditions

Ultra-Deep Sequencing Reveals the microRNA Expression Pattern of the Human Stomach

Background: While microRNAs (miRNAs) play important roles in tissue differentiation and in maintaining basal physiology, little is known about the miRNA expression levels in stomach tissue. Alterations in the miRNA profile can lead to cell deregulation, which can induce neoplasia. Methodology/Principal Findings: A small RNA library of stomach tissue was sequenced using high-throughput SOLiD sequencing technology. We obtained 261,274 quality reads with perfect matches to the human miRnome, and 42% of known miRNAs were identified. Digital Gene Expression profiling (DGE) was performed based on read abundance and showed that fifteen miRNAs were highly expressed in gastric tissue. Subsequently, the expression of these miRNAs was validated in 10 healthy individuals by RT-PCR showed a significant correlation of 83.97% (P<0.05). Six miRNAs showed a low variable pattern of expression (miR-29b, miR-29c, miR-19b, miR-31, miR-148a, miR-451) and could be considered part of the expression pattern of the healthy gastric tissue. Conclusions/Significance: This study aimed to validate normal miRNA profiles of human gastric tissue to establish a reference profile for healthy individuals. Determining the regulatory processes acting in the stomach will be important in the fight against gastric cancer, which is the second-leading cause of cancer mortality worldwide.Governo do Para/SEDECT/FAPESPAPROPESP/UFPAFADESPCAPES (Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior