Sucesión fúngica en la hojarasca de Nothofagus dombeyi

The experiment was performed in two sites of Nahuel Huapi National Park: nearby Lake Gutiérrez and Quetrihué Peninsula. The method used was direct observation on sterilized leaves previously incubated in between leaf-litter on special traps. Leaves were observed in the laboratory monthly during two years, determining tbe presence and relative frequence of fungi sporulating in both urfaces. Data obtained from both sites were used for preparing double entrance tables with taxa grouped according to Mueller-Dombois and Ellenberg (1974) method. As a result six groups of species were disitnguished; GROUP 1 represent the pioneers in the succession on fallen leaves, with Zoellneria eucalypti as dominant. GROUP II is formecl by an enclophytic fungi, Coleophoma cylindrospora and clandosporium. cladosporioides, both considered here primary saprophytes. GROUP III does not show a successional pattern and is composecl by species of diseontinuous appearence originatedin soil: we call these fungí invaders of the leaf-litter. There are Paecilomyces sp. and Acremonium sp. GROUP IV is dominatecl by Trichocladium opacum, which is an aggressive and competitive primarry saprophyte due its complex enzimatic activity. GROUP V is represented mainly by Ascomycetes, accompanied in some cases by a few aeroaquatic fungi. The fonner colonizes the leaves for a long period and can be considered secondary sapro¡phytes. GROUP VI is formed by soil and predator fungí as Monacrosporium gephyropagum and Mucor circinelloides. After 4 years and 10 month apparently the succession did not reach the "climax" state, because only about 70 % of the species found in natural leaf-litter have been detected. There is a certain coherence between SUCCESSIONAL GROUPS and SEASONAL GROUPS, th latter was reported in a previous paper.Se estudia la suces.on ue hongos sobre la hojarasca de Nothofagus dombeyi en dos sitios del Parque Nacional Nahuel Huapí: Lago Gutiérrez y Península Quetrihué (Argentina). El método seguido es el de la observación directa de las hojas esterilizadas incubadas en "trampas" especialmente ubil.:adas entre la hojarasca, las que mensualmente se analizaron en el laboratorio, determinando la presencia y frecuenda relativa (f) de los hongos aparecidos en ambas superficies fo1iares, en cada hoja. Con estos datos se confeccionaron tablas sociológicas de doble entrada, volcándose los relevamientos de taxones en cada sitio y agrupándose según la técnica de Mueller-Dombois y EJlenberg (1974). Como resultado se proponen seis GRUPOS SUCESIONALES. El GRUPO I representa las especies pioneras de la sucesión sobre las hojas caídas en el piso del bosque y su principal componente es Zoell,¡eria. etlcalypti. El GRUPO II está conformado por un hongo endofítico: Coleophoma cylindrospora y por CUIdosporill1n cladoslJOrioides, ambos salJTófitos primarios. El GRUPO III no muestra una neta distribución estacional por su aparición discontinua: está compuesto por hongos del suelo invasores de la hojarasca, como Paecilomyces sp. y Aeremonilllll Sp' El GRUPO IV, cuyo dominante es l'ric1wci(Jclium opaculll ('S un saprófito primario agresivo y competitivo por su variada actividad enzimáliea. El GRUPO V, fomlado básicamente por aswmicetes, col niza la hojarasea por un período largo, a veces están acompañados por hongos aeroacuáticos y pueden considerarse saprófitos secundarios. El GRUPO VI está conformado por hongos de suelo y depredadores, como Monacrosporium. gephyropagum y Mucor circinelloides. Al cabo de 4. años y 8 meses se percibe que la sucesión no ha llegado a su estado "clímax", ya que solamente han apareddo aproximadamente un 70 % de los taxones detectados en la hojarasca natural, empleando el muestreo mensua

Variación estacional de la micoflora en la hojarasca de Nothofagus DombeyI

Los organismos degradadores, hongos y bacterias, cumplen una función vital en los ecosistemas de bosque, manteniendo el reciclado de la materia. Aquellos actúan sobre los detritos vegetales y animales alimentando un proceso que conduce a la formación de humus y otras sustancias orgánicas y a la liberación de nutrientes que de tal manera quedan disponibles para su utilización por los productores primarios. Como este abastecimiento de nutrientes es un factor limitante, los degradadores controlan indirectamente la productividad del bosque. Además los microorganismos tienden a hacer más perfectos e intrabióticos los ciclos de los nutrientes en los ecosistemas, contribuyendo a evitar la pérdida de sustancias minerales mediante relaciones simbióticas con las raíces de las Cormofitas (micorrizas) y con la retención temporaria de nutrientes en sus talos. Por todo esto, su acción se considera de suma importancia para los sistemas ecológicos a nivel delsuelo, donde la descomposición es el proceso más activo

Clinical pharmacogenomic testing of KRAS, BRAF and EGFR mutations by high resolution melting analysis and ultra-deep pyrosequencing

BACKGROUND: Epidermal growth factor receptor (EGFR) and its downstream factors KRAS and BRAF are mutated in several types of cancer, affecting the clinical response to EGFR inhibitors. Mutations in the EGFR kinase domain predict sensitivity to the tyrosine kinase inhibitors gefitinib and erlotinib in lung adenocarcinoma, while activating point mutations in KRAS and BRAF confer resistance to the anti-EGFR monoclonal antibody cetuximab in colorectal cancer. The development of new generation methods for systematic mutation screening of these genes will allow more appropriate therapeutic choices. METHODS: We describe a high resolution melting (HRM) assay for mutation detection in EGFR exons 19-21, KRAS codon 12/13 and BRAF V600 using formalin-fixed paraffin-embedded samples. Somatic variation of KRAS exon 2 was also analysed by massively parallel pyrosequencing of amplicons with the GS Junior 454 platform. RESULTS: We tested 120 routine diagnostic specimens from patients with colorectal or lung cancer. Mutations in KRAS, BRAF and EGFR were observed in 41.9%, 13.0% and 11.1% of the overall samples, respectively, being mutually exclusive. For KRAS, six types of substitutions were detected (17 G12D, 9 G13D, 7 G12C, 2 G12A, 2 G12V, 2 G12S), while V600E accounted for all the BRAF activating mutations. Regarding EGFR, two cases showed exon 19 deletions (delE746-A750 and delE746-T751insA) and another two substitutions in exon 21 (one showed L858R with the resistance mutation T590M in exon 20, and the other had P848L mutation). Consistent with earlier reports, our results show that KRAS and BRAF mutation frequencies in colorectal cancer were 44.3% and 13.0%, respectively, while EGFR mutations were detected in 11.1% of the lung cancer specimens. Ultra-deep amplicon pyrosequencing successfully validated the HRM results and allowed detection and quantitation of KRAS somatic mutations. CONCLUSIONS: HRM is a rapid and sensitive method for moderate-throughput cost-effective screening of oncogene mutations in clinical samples. Rather than Sanger sequence validation, next-generation sequencing technology results in more accurate quantitative results in somatic variation and can be achieved at a higher throughput scale.This work was supported by grants from Spanish Health Ministry (FIS) network RIRAAF (RD 07/0064).Ye

X chromosome inactivation does not necessarily determine the severity of the phenotype in Rett syndrome patients

Rett syndrome (RTT) is a severe neurological disorder usually caused by mutations in the MECP2 gene. Since the MECP2 gene is located on the X chromosome, X chromosome inactivation (XCI) could play a role in the wide range of phenotypic variation of RTT patients; however, classical methylation-based protocols to evaluate XCI could not determine whether the preferentially inactivated X chromosome carried the mutant or the wild-type allele. Therefore, we developed an allele-specific methylation-based assay to evaluate methylation at the loci of several recurrent MECP2 mutations. We analyzed the XCI patterns in the blood of 174 RTT patients, but we did not find a clear correlation between XCI and the clinical presentation. We also compared XCI in blood and brain cortex samples of two patients and found differences between XCI patterns in these tissues. However, RTT mainly being a neurological disease complicates the establishment of a correlation between the XCI in blood and the clinical presentation of the patients. Furthermore, we analyzed MECP2 transcript levels and found differences from the expected levels according to XCI. Many factors other than XCI could affect the RTT phenotype, which in combination could influence the clinical presentation of RTT patients to a greater extent than slight variations in the XCI pattern

Genetic landscape of 6089 inherited retinal dystrophies affected cases in Spain and their therapeutic and extended epidemiological implications

Inherited retinal diseases (IRDs), defined by dysfunction or progressive loss of photoreceptors, are disorders characterized by elevated heterogeneity, both at the clinical and genetic levels. Our main goal was to address the genetic landscape of IRD in the largest cohort of Spanish patients reported to date. A retrospective hospital-based cross-sectional study was carried out on 6089 IRD affected individuals (from 4403 unrelated families), referred for genetic testing from all the Spanish autonomous communities. Clinical, demographic and familiar data were collected from each patient, including family pedigree, age of appearance of visual symptoms, presence of any systemic findings and geographical origin. Genetic studies were performed to the 3951 families with available DNA using different molecular techniques. Overall, 53.2% (2100/3951) of the studied families were genetically characterized, and 1549 different likely causative variants in 142 genes were identified. The most common phenotype encountered is retinitis pigmentosa (RP) (55.6% of families, 2447/4403). The most recurrently mutated genes were PRPH2, ABCA4 and RS1 in autosomal dominant (AD), autosomal recessive (AR) and X-linked (XL) NON-RP cases, respectively; RHO, USH2A and RPGR in AD, AR and XL for non-syndromic RP; and USH2A and MYO7A in syndromic IRD. Pathogenic variants c.3386G > T (p.Arg1129Leu) in ABCA4 and c.2276G > T (p.Cys759Phe) in USH2A were the most frequent variants identified. Our study provides the general landscape for IRD in Spain, reporting the largest cohort ever presented. Our results have important implications for genetic diagnosis, counselling and new therapeutic strategies to both the Spanish population and other related populations.This work was supported by the Instituto de Salud Carlos III (ISCIII) of the Spanish Ministry of Health (FIS; PI16/00425 and PI19/00321), Centro de Investigación Biomédica en Red Enfermedades Raras (CIBERER, 06/07/0036), IIS-FJD BioBank (PT13/0010/0012), Comunidad de Madrid (CAM, RAREGenomics Project, B2017/BMD-3721), European Regional Development Fund (FEDER), the Organización Nacional de Ciegos Españoles (ONCE), Fundación Ramón Areces, Fundación Conchita Rábago and the University Chair UAM-IIS-FJD of Genomic Medicine. Irene Perea-Romero is supported by a PhD fellowship from the predoctoral Program from ISCIII (FI17/00192). Ionut F. Iancu is supported by a grant from the Comunidad de Madrid (CAM, PEJ-2017-AI/BMD7256). Marta del Pozo-Valero is supported by a PhD grant from the Fundación Conchita Rábago. Berta Almoguera is supported by a Juan Rodes program from ISCIII (JR17/00020). Pablo Minguez is supported by a Miguel Servet program from ISCIII (CP16/00116). Marta Corton is supported by a Miguel Servet program from ISCIII (CPII17/00006). The funders played no role in study design, data collection, data analysis, manuscript preparation and/or publication decisions

Colecistectomía por minilaparotomía

[spa] La primera colecistectomía con éxito fue realizada por Carl Langenbusch de Berlín, a través de una incisión en forma de T, en 1882. Desde entonces se han descrito varios tipos de incisiones para acceder a la vesícula y realizar la colecistectomía. Las que gozan de más adeptos son la laparotomía transrectal derecha y la incisión subcostal de Kocher. Esta última es para muchos cirujanos la preferida al presentar una menor incidencia de complicaciones pulmonares y abdominales. Por término medio su longitud varía entre 15 y 30 centímetros, dependiendo de la dificultad técnica y del volumen del paciente. Durante el período de febrero a diciembre de 1991 hemos intentado desarrollar una técnica, que ya ha sido publicada con anterioridad por otros autores, que consiste en la realización de una incisión abdominal mínima para hacer patente la viabilidad de la extirpación de la vesícula por este método en nuestro medio