38 research outputs found
Complex evolution of the DAL5 transporter family
No full textGenes continuously duplicate and the duplicated copies remain in the genome or get deleted. The DAL5 subfamily of transmembrane transporter genes has eight known members in S. cerevisiae. All are putative anion:cation symporters of vitamins (such as allantoate, nicotinate, panthotenate and biotin). The DAL5 subfamily is an old and important group since it is represented in both Basidiomycetes ("mushrooms") and Ascomycetes ("yeast"). We studied the complex evolution of this group in species from the kingdom of fungi particularly the Ascomycetes. © 2008 Hellborg et al; licensee BioMed Central Ltd
Dekkera/Brettanomyces yeasts for ethanol production from renewable sources under oxygen-limited and low-pH conditions
No full textIndustrial fermentation of lignocellulosic hydrolysates to ethanol requires microorganisms able to utilise a broad range of carbon sources and generate ethanol at high yield and productivity. D. bruxellensis has recently been reported to contaminate commercial ethanol processes, where it competes with Saccharomyces cerevisiae [4, 26]. In this work Brettanomyces/Dekkera yeasts were studied to explore their potential to produce ethanol from renewable sources under conditions suitable for industrial processes, such as oxygen-limited and low-pH conditions. Over 50 strains were analysed for their ability to utilise a variety of carbon sources, and some strains grew on cellobiose and pentoses. Two strains of D. bruxellensis were able to produce ethanol at high yield (0.44 g g(-1) glucose), comparable to those reported for S. cerevisiae. B. naardenensis was shown to be able to produce ethanol from xylose. To obtain ethanol from synthetic lignocellulosic hydrolysates we developed a two-step fermentation strategy: the first step under aerobic conditions for fast production of biomass from mixtures of hexoses and pentoses, followed by a second step under oxygen limitation to promote ethanol production. Under these conditions we obtained biomass and ethanol production on synthetic lignocellulosic hydrolysates, with ethanol yields ranging from 0.2 to 0.3 g g(-1) sugar. Hexoses, xylose and arabinose were consumed at the end of the process, resulting in 13 g l(-1) of ethanol, even in the presence of furfural. Our studies showed that Brettanomyces/Dekkera yeasts have clear potential for further development for industrial processes aimed at production of ethanol from renewable sources
”Då får du vara kusin som ska på semester” En studie om inkludering och exkludering mellan barn i den fria leken
No full textSyftet med vår studie är att undersöka hur barn inkluderar och exkluderar varandra i den fria leken på förskolan samt vilka strategier de använder sig av för att göra detta. Vi vill med denna studie synliggöra barns agerande i relation till varandra för att utmana pedagogernas förhållningssätt samt handlande i barns fria lek.
Frågeställningarna som kommer att besvaras är:
● Hur kommer inkludering och exkludering till uttryck mellan barn i den fria leken?
● Vilka strategier använder barn för att inkludera och exkludera andra barn?
● Vilka strategier använder barn för att bli inkluderade i en pågående lek?
För att utföra studien valdes en kvalitativ metod för att kunna gå på djupet och få svar på ovan nämnda frågeställningar. Observationerna genomfördes under sex dagar på en förskola på en avdelning för barn i åldrarna fyra till fem år. Dessa observationer transkriberades samt kategoriserades för att sedan analyseras med hjälp av Corsaros olika teoretiska begrepp.
Studiens resultat visar att det förekommer inkludering och exkludering mellan barn i den fria leken. Barn värnar om att vara en del av en kamratkultur samt skydda denna kultur genom att inkludera eller exkludera kamraterna. I resultatet synliggörs det att barn använder sig av flera olika strategier för att bjuda in samt skydda sin pågående lek. Vid inkludering används övervägande verbala strategier men även icke-verbala strategier blir synliga. De verbala strategierna är även dominerande vid exkludering. Studiens resultat påvisar också att barn strävar efter att känna gemenskap och därmed använder sig av olika strategier för att få tillträde till en pågående lek. Barn använder sig ofta av flera strategier när den första inte leder till framgång. Resultatet visar att en och samma strategi kan generera i olika framgångar samt konsekvenser. Därmed blir strategierna situationsbundna beroende på dess kontext och vilka relationer leken består av
Evolutionary Studies of the Mammalian Y Chromosome
No full textSex chromosomes are useful in elucidating the evolutionary factors affecting diversity and divergence. In particular, Y chromosome analyses may complement studies using mitochondrial DNA for inferring sex-specific population genetic processes. Y chromosome studies have been scarce due to limited access to genetic markers and the dynamic evolution of Y. Conserved Y-specific primers that could amplify a diverse set of mammalian species were developed from comparison of gametologous X and Y sequences. Y-specific sequence, generally more than one kb, was amplified for all 20 species examined. Intraspecific diversity on mammalian Y was found to be reduced even when male-biased mutation rate and effective population size were corrected for. A number of factors can cause this low variation on Y of which selection on a haploid chromosome seems most important. The field vole (Microtus agrestis), a common and well-studied small mammal in Eurasia, was examined for X and Y variability. Earlier studies on mtDNA had shown that the field vole is separated in two distinct lineages in Europe. The X and Y chromosome sequences confirmed the deep split and suggested that the two lineages of field vole should be reclassified as two separate species. Two distinct Y chromosome haplogroups were found in modern European cattle, distributed among breeds according to a north-south gradient. Ancient DNA analysis of European aurochsen showed the northern haplogroup to be the most common, possibly indicating local hybridization between domestic cows and wild aurochs bulls in Europe
Analysis of three compositions by bassist Jonas Hellborg based on South Indian musical elements
No full textEste documento tiene como propósito comprender la organización de los recursos extraídos de la música de la cultura de la India, como componentes estructurales, en composiciones que integran, también, géneros provenientes de la cultura occidental. El autor presenta un recuento acerca del desarrollo de la música desde la etapa temprana en la formación de esta cultura surasiática, e incluye un capítulo como puente cronológico que conecta los primeros contactos de la música de la India con occidente, llegando al trabajo discográfico de Jonas Hellborg. Es necesario un aprestamiento básico desde aspectos fundamentales de la música: forma, melodía y ritmo, por lo cual, gran parte de este trabajo está dedicado a entender dichos aspectos desde la perspectiva de la tradición carnática y consolidarlos en el lenguaje de la música occidental o sistema diastemático, con un importante grado de aproximación para su entendimiento dentro de la academia.The purpose of this document is to understand the organization of the resources extracted from the music of Indian culture, as structural components, in compositions that also integrate genres from Western culture. The author presents an account of the development of music from the early stage in the formation of this South Asian culture, and includes a chapter as a chronological bridge that connects the first contacts of Indian music with the West, reaching the Jonas Hellborg's record work. A basic preparation is necessary from fundamental aspects of music: form, melody and rhythm, therefore, a large part of this work is dedicated to understanding these aspects from the perspective of the carnatic tradition and consolidating them in the language of Western music or diastemmatic system, with an important degree of approximation for its understanding within the academy
Complex Nature of the Genome in a Wine-spoilage Yeast, Dekkera bruxellensis.
No full textWhen the genome organization of thirty native isolates belonging to a wine-spoilage yeast Dekkera/Brettanomyces bruxellensis, a distant relative of Saccharomyces cerevisiae, was examined, the number of chromosomes varied drastically, from 4 to at least 9. When single gene probes were used in Southern analysis, the corresponding genes usually mapped to at least two chromosomal bands, excluding a simple haploid organization of the genome. When different loci were sequenced, in most cases several different haplotypes were obtained in each single isolate, and they belonged to two sub-types. Phylogenetic reconstruction using haplotypes revealed that the sequences from different isolates, belonging to one sub-type, were more similar to each other than to the sequences belonging to the other sub-type, within the isolate. Reanalysis of the genome sequence confirmed that also the partially sequenced strain Y879 is not a simple hybrid and its genome contains of app. 1% polymorphic sites. The present situation could be explained by (i) a hybridization event where two similar but different genomes have recently fused together or, (ii) that the diploid progenitor of all analyzed strains lost a regular sexual cycle and the genome started to accumulate mutations
Parallel evolution of the make-accumulate-consume strategy in Saccharomyces and Dekkera yeasts
No full textSaccharomyces yeasts degrade sugars to two-carbon components, in particular ethanol, even in the presence of excess oxygen. This characteristic is called the Crabtree effect and is the background for the 'make-accumulate-consume' life strategy, which in natural habitats helps Saccharomyces yeasts to out-compete other microorganisms. A global promoter rewiring in the Saccharomyces cerevisiae lineage, which occurred around 100 mya, was one of the main molecular events providing the background for evolution of this strategy. Here we show that the Dekkera bruxellensis lineage, which separated from the Saccharomyces yeasts more than 200 mya, also efficiently makes, accumulates and consumes ethanol and acetic acid. Analysis of promoter sequences indicates that both lineages independently underwent a massive loss of a specific cis-regulatory element from dozens of genes associated with respiration, and we show that also in D. bruxellensis this promoter rewiring contributes to the observed Crabtree effect
A Near-extinction Event in Lynx: Do Microsatellite Data Tell the Tale?
No full textFluctuations in population size can have a profound impact on effective population size and the maintenance of genetic variation within a population. A number of tests based on microsatellite data have been developed for the detection of bottleneck events in a population's past. In this paper, we search for signs of a bottleneck in microsatellite data on the Scandinavian lynx (Lynx lynx) population. This population was hunted to the brink of extinction, with fewer than 100 animals (one estimate was as low as 30 individuals) remaining in the late 1920s. Protection allowed recovery of the population, which currently numbers about 2000 adults. Despite this pronounced demographic bottleneck (more than 95% of the population was killed), we could find no conclusive genetic evidence of a bottleneck using four of the recently developed tests for detecting such events
