Ensayo de PCR multiplex para la detección en leche del género Salmonella, la subespecie I y el serotipo Typhimurium

Gastrointestinal disea ses  caused  by  foodstuffs  contaminated with  Salmonella entérica implicate  important  social  and economic  issues,  making  it  necessary  to  have  fast,  sensitive,  and  specific  systems  for  opportune  detection  of  the pathogen.  An  endpoint  PCR  protocol  for  identification  of  S.  entérica in  milk  is  presented  using  primer  pairs previously  validated  as  specific  to  the  genus  Salmonella (STM3098-f2/STM3098-r2),  subspecies  entérica (subspecies  I)  (STM4057-f/STM4057-r),  and  serotype  Typhimurium  (STM4497-f/  STM4497-r).  This  protocol allowed  for  detection  of  1  CFU/25  mL  of  spiked  milk  after  a  12  h  pre-enrichment  period  by  means  of  simple  and multiplex  PCR  assay  with  the  three  used  primer  pairs.  The  designed  protocol  can  be  applied  in  sanita ry  survey programs  for  detection  of  S.  entérica in  milk.Debido a la importancia social y económica de las enfermedades gastrointestinales causadas por alimentos contaminados con Salmonella enterica, es necesario contar con sistemas de detección rápidos, sensibles y específicos para la detección oportuna de dicho patógeno. En este trabajo se presenta un protocolo de PCR de punto final para la identificación de S. enterica en leche, que utiliza los pares de iniciadores STM3098-f2/STM3098-r2, STM4057-f/STM4057-r y STM4497-f/STM4497-r previamente validados como específicos del género Salmonella, de la subespecie I y del serotipo Typhimurium, respectivamente. El protocolo presentado permite la detección de 1 UFC/25 ml de leche contaminada artificialmente, con un periodo de pre-enriquecimiento de 12 h, en ensayos de PCR simple y multiplex con los tres pares de iniciadores. El protocolo diseñado puede ser aplicado en sistemas de vigilancia sanitaria para la detección de S. enterica en leche

Ascomicetos hipogeos de la región occidental del Sistema Volcánico Transversal, México

Background and Aims: In Mexico, 42 species of ascomycetes have been reported with hypogeous habit, which are few considering the knowledge of other groups of fungi. The purpose of this paper is to increase the knowledge about the diversion and distribution of hypogeous fungi species for Mexico.Methods: Specimens were collected from different types of vegetation in the western portion of the transverse volcanic system, located in the state of Michoacán. The specimens collected were pictured and described following the protocols for the group.Key results: We present the description and discussion of six species of ascomycetes with hypogeous habit, Elaphomyces appalachiensis, Genea mexicana, Genabea cerebriformis, Hydnobolites cerebriformis, Tuber pseudoseparans and T. tequilanum.Conclusions: The records of these species represent new collection sites for Mexico and first records for the mycobiota of the state of Michoacán. It increases the distribution of Elaphomyces appalachiensis, Genabea cerebriformis and Hydnobolites cerebriformis, known from the United States of America and northern Mexico, to the Transversal Volcanic System, while Genea mexicana, Tuber pseudoseparans and T. tequilanum only are known in this mountainous system.Antecedentes y Objetivos: En México se han reportado 42 especies de ascomicetos con hábito hipogeo; son pocas considerando el conocimiento de otros grupos de hongos. El objetivo de este trabajo fue incrementar el conocimiento sobre la diversidad y distribución de especies de hongos hipogeos para México.Métodos: Se realizaron recolectas en diversos tipos de vegetación del Sistema Volcánico Transversal en la porción occidental perteneciente al estado de Michoacán. El material se fotografió y describió siguiendo los protocolos para el grupo.Resultados clave: Se presentan la descripción y discusión de seis especies de ascomicetos con hábito hipogeo, Elaphomyces appalachiensis, Genea mexicana, Genabea cerebriformis, Hydnobolites cerebriformis, Tuber pseudoseparans y T. tequilanum.Conclusiones: Los registros representan nuevas localidades para el país y primeras citas para la micobiota del estado de Michoacán. Se incrementa la distribución de Elaphomyces appalachiensis, Genabea cerebriformis e Hydnobolites cerebriformis, conocidos de los Estados Unidos de América y el Norte de México, hasta el Sistema Volcánico Transversal, mientras que Genea mexicana, Tuber pseudoseparans y T. tequilanum solo se conocen en este sistema montañoso

MicroRNAs Associated with Secondary Metabolites Production

MicroRNAs (miRNAs) are noncoding RNAs that play an important role in the regulation of the genetic expression in animals and plants by targeting mRNAs for cleavage or translational repression. Several miRNAs regulate the plant development, the metabolism, and the responses to biotic and abiotic stresses. Characterization of an miRNA has helped to show its role in fine tuning the mechanisms of posttranscriptional gene regulation. Although there is a lot of information related to miRNA regulation of some processes, the role of miRNA involved in the regulation of biosynthesis of secondary plant product is still poorly understood. In this chapter, we summarize the identification and characterization of miRNAs that participate in the regulation of the biosynthesis of secondary metabolites in plants and their use in the strategies to manipulate a controlled manipulation

Detecting patterns of fertilization and frequency of multiple paternity in Chelonia mydas of Colola (Michoacán, Mexico)

We present a microsatellite analysis that allows an indirect determination of the process of fertilization in the genital tract of Chelonia mydas. The strategy was based in that the order of oviposition is related to fertilization order. Once the genotype of the offspring was obtained through microsatellite analyses, it was possible to determine the frequency of multiple paternity and to infer the presence of anatomical structures or physiological mechanisms that allow females to undergo cryptic choice processes, which allowed us to hypothesize the existence of post-copula factors that determine reproductive success in a polyandrous system. This paper does not show the presence of physiological mechanisms that allow control of fertilization order in polyandrous females of Chelonia mydas

Structural and phylogenetic analysis of laccases from Trichoderma: a bioinformatic approach.

The genus Trichoderma includes species of great biotechnological value, both for their mycoparasitic activities and for their ability to produce extracellular hydrolytic enzymes. Although activity of extracellular laccase has previously been reported in Trichoderma spp., the possible number of isoenzymes is still unknown, as are the structural and functional characteristics of both the genes and the putative proteins. In this study, the system of laccases sensu stricto in the Trichoderma species, the genomes of which are publicly available, were analyzed using bioinformatic tools. The intron/exon structure of the genes and the identification of specific motifs in the sequence of amino acids of the proteins generated in silico allow for clear differentiation between extracellular and intracellular enzymes. Phylogenetic analysis suggests that the common ancestor of the genus possessed a functional gene for each one of these enzymes, which is a characteristic preserved in T. atroviride and T. virens. This analysis also reveals that T. harzianum and T. reesei only retained the intracellular activity, whereas T. asperellum added an extracellular isoenzyme acquired through horizontal gene transfer during the mycoparasitic process. The evolutionary analysis shows that in general, extracellular laccases are subjected to purifying selection, and intracellular laccases show neutral evolution. The data provided by the present study will enable the generation of experimental approximations to better understand the physiological role of laccases in the genus Trichoderma and to increase their biotechnological potential

Synonymous and non-synonymous substitution rates (%) between lacccase genes of <i>Trichoderma</i> spp.

<p>Genes designed as in the JGI GeneBank. ^aps, percentage of synonymous substitutions; pn, percentage of non-synonymous substitutions; pn/ps, ratio of synonymous, non synonymous substitutions.</p

Comparative Genomic Analysis Discloses Differential Distribution of Antibiotic Resistance Determinants between Worldwide Strains of the Emergent ST213 Genotype of Salmonella Typhimurium

Salmonella enterica constitutes a global public health concern as one of the main etiological agents of human gastroenteritis. The Typhimurium serotype is frequently isolated from human, animal, food, and environmental samples, with its sequence type 19 (ST19) being the most widely distributed around the world as well as the founder genotype. The replacement of the ST19 genotype with the ST213 genotype that has multiple antibiotic resistance (MAR) in human and food samples was first observed in Mexico. The number of available genomes of ST213 strains in public databases indicates its fast worldwide dispersion, but its public health relevance is unknown. A comparative genomic analysis conducted as part of this research identified the presence of 44 genes, 34 plasmids, and five point mutations associated with antibiotic resistance, distributed across 220 genomes of ST213 strains, indicating the MAR phenotype. In general, the grouping pattern in correspondence to the presence/absence of genes/plasmids that confer antibiotic resistance cluster the genomes according to the geographical origin where the strain was isolated. Genetic determinants of antibiotic resistance group the genomes of North America (Canada, Mexico, USA) strains, and suggest a dispersion route to reach the United Kingdom and, from there, the rest of Europe, then Asia and Oceania. The results obtained here highlight the worldwide public health relevance of the ST213 genotype, which contains a great diversity of genetic elements associated with MAR