Effect of huitlacoche (Ustilago maydis DC Corda) paste addition on functional, chemical and textural properties of tortilla chips

AbstractThis study analyzed the addition of huitlacoche paste (HP) in baked tortilla chips (TC), evaluating its effects on functional, physicochemical and structural changes during processing. Two blue corn grains were nixtamalized, stone milled, air dried and milled to obtain flour; commercial blue corn flour (TM1) and commercial TC (TM2) were used as controls. Additions of 0, 3, 6 and 9% of HP were formulated; masas were prepared at 55% moisture content (MC), precooked and baked in an industrial machine. TC crispiness was influenced by grain characteristics and percentage of HP. Huitlacoche paste addition caused an increase in total dietary fiber (from 5.27 to 14.54%), total soluble phenolics content (from 17.52 to 37.60 mg GAE/100 g) and antioxidant capacity (from 6.74 to 7.98 μmol TE/g) in TC. Results suggest that tortilla chips added with huitlacoche can be an alternative to prepare this traditional edible fungus and produce healthier snacks, not fried and enriched with bioactive compounds.

Análisis de expresión del gen homologo GPI1 de saccharomyces cerevisiae en ustilago maydis.

Tesis (Maestro en Ciencias con acentuación en Microbiología) UANL, 2014.

Caracterización de la expresión génica en respuesta a estrés alcalino en U. maydis mediada por el factor de transcripción Rim101

Tesis (Doctor en Ciencias con especialidad en Microbiología) UANL, 2014.

Diallel analysis of maize resistance to Phaeosphaeria maydis

Em programas de melhoramento visando resistência genética a doenças, a estimativa de parâmetros genéticos que governam a resistência permite direcionar a introdução de resistência em germoplasmas. O objetivo deste trabalho foi estimar os efeitos heteróticos, a capacidade geral (CGC) e específica (CEC) de combinação, utilizando-se de dois métodos de avaliação da resistência, à Phaeosphaeria maydis através da análise dialélica de 36 híbridos F1 e de suas nove linhagens genitoras, em experimentos conduzidos em três ambientes. Foi utilizado um delineamento experimental em blocos casualizados com três repetições e a parcela experimental foi representada por uma fileira de 5 m. As diferenças entre as estimativas da capacidade de combinação, em diferentes ambientes e para os dois métodos de avaliação, apresentaram efeitos significativos (P < 0.01) para ambientes (E), CGC e CGC x E. O efeito de CEC e a interação CEC x E não foi significativa para os dois métodos de avaliação. Os efeitos de CGC foram mais importantes que CEC nesse conjunto de linhagens, sugerindo que efeitos genéticos aditivos são mais importantes como fonte de variação para resistência a esta doença. Efeitos heteróticos para resistência foram estimados, sendo possível identificar combinações híbridas específicas entre linhagens com alto potencial para o controle genético deste patógeno. Resultados para os dois métodos de avaliação foram praticamente idênticos, embora o método PI seja de maior praticidade de uso.

Sensibilidade de stenocarpella macrospora a fungicidas

The application of fungicides in the aerial organs is control strategy to macrospora spot caused by fungus Stenocarpella macrospora. The objective of this study was to determine the sensitivity of S. macrospora to fungicides by inhibition of mycelial growth (MG) and conidial germination (CG). It was eval uated 12 fungicides belonging to the chemical groups of the benzimidazoles, triazoles and strobilurins, six concentrations and two isolates of the fungus (SC and MT). The fungicides were diluted in sterile distilled water and added to the culture medium of potato dextrose agar (mycelium) and water-agar (spore) after sterilization. The percentage of inhibition of MC and CG was calculed in comparison with control, estimating of 50% inhibitory concentration (IC50). The fungicides tested were effective in inhibiting the MC. The IC50 was less than 1 ppm for all fungicides. There was no difference between isolates. The inhibition of CG had higher fungitoxicity strobilurins, and the IC50 was between 0.0035 and 0.03 ppm, and the isolated SC showed the higher sensitivity to the fungicides. The IC50 values obtained for fungicides and specific S. macrospora will be useful in monitoring the sensitivity of the fungus, especially in regions with intense demand for fungicides in corn.

Aspectos biológicos y poblacionales de Sipha Maydis (Passerini) y Schizaphis Graminum (Rondani) en cebada

El objetivo del presente estudio fue obtener los parámetros bioetológicos de Sipha maydis (Passerini) y Schizaphis graminum (Rondani) sobre cebada, Hordeum vulgare L. cv. Pampa. Los pulgones se criaron en condiciones de laboratorio a 20±1 °C, 14:10 horas de fotofase y una humedad relativa del 50-70 %. Se obtuvieron cohortes a partir de poblaciones de estos áfidos, sobre las que se realizó el registro diario de los cambios de estado, número de individuos muertos y los nacimientos una vez alcanzado el estado adulto. Se analizaron las curvas de supervivencia por edades (lx) y fecundidad (mx) y los siguientes estadísticos vitales: tasa reproductiva neta (Ro); tasa intrínseca de crecimiento natural (rm); tiempo generacional medio (T) y tiempo de duplicación (D). Para la comparación de las rm se obtuvieron las rm estimadas junto con su error standard mediante el procedimiento <jackknife». Si bien el pulgón verde de los cereales S. graminum posee mayor eficiencia reproductiva, S. maydis presenta valores de supervivencia y fecundidad de importancia, que indicaría que este áfido podría constituirse en una plaga potencial de gramíneas cultivadas.

Isolation of human and mouse genes based on homology to REC2, a recombinational repair gene from the fungus Ustilago maydis

A human and a mouse gene have been isolated based on homology to a recombinational repair gene from the corn smut Ustilago maydis. The new human (h) gene, termed hREC2, bears striking resemblance to several others, including hRAD51 and hLIM15. hREC2 is located on human chromosome 14 at q23–24. The overall amino acid sequence reveals characteristic elements of a RECA-like gene yet harbors an src-like phosphorylation site curiously absent from hRAD51 and hLIM15. Unlike these two relatives, hREC2 is expressed in a wide range of tissues including lung, liver, placenta, pancreas, leukocytes, colon, small intestine, brain, and heart, as well as thymus, prostate, spleen, and uterus. Of greatest interest is that hREC2 is undetectable by reverse transcription-coupled PCR in tissue culture unless the cells are treated by ionizing radiation.

Recombinational repair of gaps in DNA is asymmetric in Ustilago maydis and can be explained by a migrating D-loop model.

Recombinational repair of double-stranded DNA gaps was investigated in Ustilago maydis. The experimental system was designed for analysis of repair of an autonomously replicating plasmid containing a cloned gene disabled by an internal deletion. It was discovered that crossing over rarely accompanied gap repair. The strong bias against crossing over was observed in three different genes regardless of gap size. These results indicate that gap repair in U. maydis is unlikely to proceed by the mechanism envisioned in the double-stranded break repair model of recombination, which was developed to account for recombination in Saccharomyces cerevisiae. Experiments aimed at exploring processing of DNA ends were performed to gain understanding of the mechanism responsible for the observed bias. A heterologous insert placed within a gap in the coding sequence of two different marker genes strongly inhibited repair if the DNA was cleaved at the promoter-proximal junction joining the insert and coding sequence but had little effect on repair if the DNA was cleaved at the promoter-distal junction. Gene conversion of plasmid restriction fragment length polymorphism markers engineered in sequences flanking both sides of a gap accompanied repair but was directionally biased. These results are interpreted to mean that the DNA ends flanking a gap are subject to different types of processing. A model featuring a single migrating D-loop is proposed to explain the bias in gap repair outcome based on the observed asymmetry in processing the DNA ends.

Respuesta a estrés iónico/Ph alcalino en ustilago maydis (Stevenson and Johnson, 1944) (ustilaginales, ustilaginaceae)

Todo organismo se enfrenta a condiciones desafiantes durante su desarrollo; variaciones de temperatura, humedad, presión osmótica y de pH, esta última condición se ve implicada en el grado de disponibilidad de nutrientes, entre ellos los metales, cuya solubilidad depende del pH del medio, por lo que la homeostasis de las concentraciones intracelulares de iones es fundamental para la fisiología de todo organismo vivo. El zinc forma parte estructural y es cofactor catalítico de numerosas enzimas y factores de transcripción, es por ello, que el transporte del metal está altamente regulado. Se han descrito transportadores de zinc y/o hierro pertenecientes a la familia ZIP, donde los principales representantes son Zrt1p y Zrt2p de alta y baja afinidad a zinc respectivamente, expresados ante condiciones limitantes de zinc en la levadura Saccharomyces cerevisiae. En el presente estudio fueron caracterizados 2 genes que codifican para transportadores de zinc en el hongo basidiomiceto Ustilago maydis; el gen codificado en el marco de lectura abierto um00096 corresponde a un transportador de alta afinidad a zinc, siendo ortólogo a ZRT1 de S. cerevisiae, mientras que el gen codificado en el marco um03110 presentó menor afinidad por el metal, nuestros resultados indican que pudiese ser transportador de otro metal. Mediante transcripción reversa y reacción en cadena de polimerasa punto final (RTPCR), se identificó que el factor de transcripción Rim101p participa en la regulación del gen ZRT2 de U. maydis, actuando como represor, en ambientes ácidos y limitantes de zinc, y como activador en pH neutro y bajas concentraciones de zinc.

Identification of a putative gene responsive to the fungus bipolaris maydis in guinea grass

2015

Incidência de Helmintosporiose (Bipolaris maydis) em capim Piatã cultivado em um sistema silvipastoril com eucalipto.

2016

Environmental stresses inhibit splicing in the aquatic fungus Blastocladiella emersonii

Background: Exposure of cells to environmental stress conditions can lead to the interruption of several intracellular processes, in particular those performed by macromolecular complexes such as the spliceosome. Results: During nucleotide sequencing of cDNA libraries constructed using RNA isolated from B. emersonii cells submitted to heat shock and cadmium stress, a large number of ESTs with retained introns was observed. Among the 6,350 ESTs obtained through sequencing of stress cDNA libraries, 181 ESTs presented putative introns (2.9%), while sequencing of cDNA libraries from unstressed B. emersonii cells revealed only 0.2% of ESTs containing introns. These data indicate an enrichment of ESTs with introns in B. emersonii stress cDNA libraries. Among the 85 genes corresponding to the ESTs that retained introns, 19 showed more than one intron and three showed three introns, with intron length ranging from 55 to 333 nucleotides. Canonical splicing junctions were observed in most of these introns, junction sequences being very similar to those found in introns from genes previously characterized in B. emersonii, suggesting that inhibition of splicing during stress is apparently a random process. Confirming our observations, analyses of gpx3 and hsp70 mRNAs by Northern blot and S1 protection assays revealed a strong inhibition of intron splicing in cells submitted to cadmium stress. Conclusion: In conclusion, data indicate that environmental stresses, particularly cadmium treatment, inhibit intron processing in B. emersonii, revealing a new adaptive response to cellular exposure to this heavy metal.

Searching for Moniliophthora perniciosa pathogenicity genes

The basidiomycete Moniliophthora perniciosa is the causal agent of witches` broom disease of Theobroma cacao (cacao). Pathogenesis mechanisms of this hemibiotrophic fungus are largely unknown. An approach to identify putative pathogenicity genes is searching for sequences induced in mycelia grown under in vitro conditions. Using this approach, genes from M. perniciosa induced under limiting nitrogen and light were identified from a cDNA library enriched by suppression subtractive hybridization as potential putative pathogenicity genes. From the 159 identified unique sequences, 59 were annotated and classified by gene ontology. Two sequences were categorized as ""Defence genes, Virulence, and Cell response"" presumably coding for allergenic proteins, whose homologues from other fungi are inducers of animal or plant defences. Differential gene expression was evaluated by quantitative amplification of reversed transcripts (RT-qPCR) of the putative identified genes coding for the two allergenic proteins (Aspf13 and 88KD), and for the enzymes Arylsulfatase (AS); Aryl-Alcohol Oxidase; Aldo-Keto Reductase (AK); Cytochrome P450 (P450); Phenylalanine Ammonia-Lyase; and Peroxidase from mycelia grown under contrasting N concentrations. All genes were validated for differential expression, except for the putative Peroxidase. The same eight genes were analysed for expression in susceptible plants inoculated with M. perniciosa, and six were induced during the early asymptomatic stage of the disease. In infected host tissues, transcripts of 88KD and AS were found more abundant at the biotrophic phase, while those from Aspf13, AK, PAL, and P450 accumulated at the necrotrophic phase, enabling to suggest that mycelia transition from biotrophic to necrotrophic might occur earlier than currently considered. These sequences appeared to be virulence life-style genes, which encode factors or enzymes that enable invasion, colonization or intracellular survival, or manipulate host factors to benefit the pathogen`s own survival in the hostile environment. (C) 2010 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.

Progeny evaluation for resistance to Phaeosphaeria leaf spot in tropical maize

Maize breeding programmes in Brazil and elsewhere seek reliable methods to identify genotypes resistant to Phaeosphaeria leaf spot. The area under the disease progress curve (AUDPC) is an accurate method to evaluate the severity of foliar diseases. However, at least three data points are required to calculate the AUDPC, which is unfeasible when there are thousands of genotypes to be assessed. The aim of this work was to estimate the heritability of disease resistance, evaluate disease severity at different times using a nine-point scale in comparison to the AUDPC, and establish the most suitable phenological period for disease assessment. A repeated experiment was conducted in a 11 x 11 lattice experimental design with three replications. Disease assessments were carried out at flowering, 15 and 30 days post-anthesis for the parental lines DS95, DAS21, the F1 generation and 118 F2:3 progenies. Then, the AUDPC was obtained and results compared with the single-point evaluations used to calculate it. Individual and joint analyses of variance were conducted to obtain heritabiliy estimates. The assessments performed after the flowering stage gave higher estimates of heritability and correlation with AUDPC. We concluded that one assessment between the 15th and 30th day after flowering could provide enough information to distinguish maize genotypes for their resistance to Phaeosphaeria leaf spot under tropical conditions.