Search results for "Hybridization"
showing 10 items of 812 documents
Treatment of a submerged anaerobic membrane bioreactor (SAnMBR) effluent by an activated sludge system: the role of sulphide and thiosulphate in the …
2014
This work studies the use of a well-known and spread activated sludge system (UCT configuration) to treat the effluent of a submerged anaerobic membrane bioreactor (SAnMBR) treating domestic waste-water. Ammonia, phosphate, dissolved methane and sulphide concentrations in the SAnMBR effluent were around 55 mg NH4-N L-1, 7 mg PO4-P L-1, 30 mg non-methane biodegradable COD L-1, and 105 mg S2- L-1 respectively. The results showed a nitrification inhibition caused by the presence of sulphur compounds at any of the solids retention time (SRT) studied (15,20 and 25 days). This inhibition could be overcome increasing the hydraulic retention time (HRT) from 13 to 26 h. Among the sulphur compounds, …
Reliable method for assessing the COD mass balance of a submerged anaerobic membrane bioreactor (SAMBR) treating sulphate-rich municipal wastewater
2012
The anaerobic treatment of sulphate-rich wastewater causes sulphate reducing bacteria (SRB) and methanogenic archaea (MA) to compete for the available substrate. The outcome is lower methane yield coefficient and, therefore, a reduction in the energy recovery potential of the anaerobic treatment. Moreover, in order to assess the overall chemical oxygen demand (COD) balance, it is necessary to determine how much dissolved CH4 is lost in the effluent. The aim of this study is to develop a detailed and reliable method for assessing the COD mass balance and, thereby, to establish a more precise methane yield coefficient for anaerobic systems treating sulphate-rich wastewaters. A submerged anaer…
Interactions between calcium precipitation and the polyphosphate-accumulating bacteria metabolism
2007
A sequencing batch reactor that is operated for biological phosphorus removal has been operated under different influent calcium concentrations to study the precipitation process and the possible effects of phosphorus precipitation in the biological phosphorus removal process. Four experiments were carried out under different influent calcium concentrations ranging from 10 to 90 g Ca m(-3). The experimental results and the equilibrium study, which are based on the saturation index calculation, confirm that the process controlling the calcium behaviour is the calcium phosphate precipitation. This precipitation takes place at two stages: initially, precipitation of the amorphous calcium phosp…
Prevalence of Angelman syndrome and Prader-Willi syndrome in Estonian children: sister syndromes not equally represented.
2006
In 2000-2004, we performed a focused search for individuals with Angelman syndrome (AS) and Prader-Willi syndrome (PWS) aiming to establish the prevalence data for the individuals born between 1984 and 2004 in Estonia. All persons with probable AS or PWS (n = 184) were studied using the DNA methylation test. Individuals with abnormal methylation were all further tested by chromosomal and FISH analysis, and if necessary for uniparental disomy and UBE3A gene mutation. Nineteen cases with abnormal methylation test result were identified. Seven of them had AS, including six (85.7%) due to 15q11-13 deletion and one paternal UPD15. Twelve subjects had PWS: 4 (33%) 15q11-13 deletions, 6 (50%) mate…
Recomendaciones para la determinación de HER2 en cáncer de mama. Consenso Nacional de la Sociedad Española de Anatomía Patológica ( SEAP ) y de la So…
2009
La identificación de los carcinomas de mama con amplificación/sobreexpresión de HER2 es crítica en la práctica clínica diaria ya que estas neoplasias requieren un tratamiento específico que incluye el uso de terapias dirigidas. Tanto las técnicas de hibridación in situ como las técnicas inmunohistoquímicas son métodos apropiados para la identificación de cánceres de mama HER2 positivos. Sin embargo, numerosos estudios, incluidos los desarrollados por la Asociación para la Garantía de Calidad en Patología de la SEAP (AGCP) y la experiencia de centros de referencia nacionales en la determinación de HER2 han puesto de manifiesto importantes problemas de reproducibilidad entre laboratorios. Por…
Genetic and Ecotypic Differentiation in a Californian Plant Polyploid Complex (Grindelia, Asteraceae)
2014
Studies of ecotypic differentiation in the California Floristic Province have contributed greatly to plant evolutionary biology since the pioneering work of Clausen, Keck, and Hiesey. The extent of gene flow and genetic differentiation across interfertile ecotypes that span major habitats in the California Floristic Province is understudied, however, and is important for understanding the prospects for local adaptation to evolve or persist in the face of potential gene flow across populations in different ecological settings. We used microsatellite data to examine local differentiation in one of these lineages, the Pacific Coast polyploid complex of the plant genus Grindelia (Asteraceae). W…
On the complexity of the Saccharomyces bayanus taxon: Hybridization and potential hybrid speciation
2014
Although the genus Saccharomyces has been thoroughly studied, some species in the genus has not yet been accurately resolved; an example is S. bayanus, a taxon that includes genetically diverse lineages of pure and hybrid strains. This diversity makes the assignation and classification of strains belonging to this species unclear and controversial. They have been subdivided by some authors into two varieties (bayanus and uvarum), which have been raised to the species level by others. In this work, we evaluate the complexity of 46 different strains included in the S. bayanus taxon by means of PCR-RFLP analysis and by sequencing of 34 gene regions and one mitochondrial gene. Using the sequenc…
Reconstruction of the evolutionary history of Saccharomyces cerevisiae x S. kudriavzevii hybrids based on multilocus sequence analysis.
2012
In recent years, interspecific hybridization and introgression are increasingly recognized as significant events in the evolution of Saccharomyces yeasts. These mechanisms have probably been involved in the origin of novel yeast genotypes and phenotypes, which in due course were to colonize and predominate in the new fermentative environments created by human manipulation. The particular conditions in which hybrids arose are still unknown, as well as the number of possible hybridization events that generated the whole set of natural hybrids described in the literature during recent years. In this study, we could infer at least six different hybridization events that originated a set of 26 S…
Use of functional genes to quantify denitrifiers in the environment.
2006
During the last decade, application of molecular methods using cultivation-independent approaches has provided new insights into the composition and structure of denitrifying communities in various environments. However, little is known about their abundance, and quantification is still performed using cultivation-based approaches, which are not only biased by the inability to cultivate of many micro-organisms but also fastidious and time-consuming. Two types of cultivation-independent approaches have recently been developed to quantify denitrifiers. The first type, which is based on the hybridization technique, comprises the use of Southern hybridization and DNA arrays. The second type, ba…
Past climate changes facilitated homoploid speciation in three mountain spiny fescues (Festuca, Poaceae)
2016
Apart from the overwhelming cases of allopolyploidization, the impact of speciation through homoploid hybridization is becoming more relevant than previously thought. Much less is known, however, about the impact of climate changes as a driven factor of speciation. To investigate these issues, we selected Festuca picoeuropeana, an hypothetical natural hybrid between the diploid species F. eskia and F. gautieri that occurs in two different mountain ranges (Cantabrian Mountains and Pyrenees) separated by more than 400 km. To unravel the outcomes of this mode of speciation and the impact of climate during speciation we used a multidisciplinary approach combining genome size and chromosome coun…