Xylan containing only xylose residues has been prepared from esparto grass, the combined glucose and arabinose extracted with xylan was removed by fractional precipitation. The sugar obtained on hydrolysis was estimated by several methods - particularly by the standardised filter paper chromatography, and the polysaccharide was found to be 98-99% pure. It was completely methylated with caustic soda and dimethyl sulphate without any degradation, and the components of the hydrolysate of the methylated xylan was effectively separated in a cellulose column with petrol-n-butanol (7:3) mixture. The end group was characterised as 2:3:4 trimethyl D-xylopyranose and amounted to one mol. in every 35 + 3 residues. No arabofuranose derivative could be detected. 2-Methyl xylose was also obtained in almost the same proportion. The different methylated sugars obtained on hydrolysis were also estimated by paper partition chromatography by stoichiometric oxidation of the extracted sugars in an improved alkaline-phosphate buffer instead of carbonate-bicarbonate buffer, and was found to be of the same order. Viscosity measurements of the acetylated and the methylated xylan , and the osmotic pressure measurement of the latter showed a degree of polymerisation of 70-80. The same number of residues in the molecule was also indicated by periodate oxidation of the xylan and the estimation of the reducing group by colorimetric determination reduction of 3:5 dinitrosalicylic acid. On the basis of these results it is suggested that an esparto xyla molecule contains about 75 + 5 xylopyranose units joined by 1:4 B-linkages with a single branching point formed by a 1:3 union at Some point in the chain. A similar examination of xylan from pear cell-wall material was found to be structurally different from that of esparto grass. The amount of end group separated in the column on hydrolysis of the methylated polysaccharide corresponded to one non-reducing end 60 residues, and it was also identified as 2:3:4 trimethyl D-xylopyranose. The cellulose column was so efficient as to quantitatively separate a mixture of 2:3:4 trimethyl xylose and 2:3 dimethyl xylose on a semi-micro scale. The estimation of the end group by paper chromatography and the determination of the chain length by periodate oxidation showed a similar degree of polymerisation, but the molecular weight calculated from the specific viscosity of methylate xylan showed value of about half that obtained for the corresponding derivative of xylan from esparto grass. These result are in favour of a straight chain formulation of 55-60 residues as the interpretation of viscosity measurement is open to doubt; however, a branched chain formulation cannot be entirely dismissed without an accurate determination of the molecular weight by osmotic pressure measurements.

No description available.

No description available.

El refuerzo es un proceso psicológico complejo mediante el cual los animales modifican su comportamiento frente situaciones que les resultan ventajosas. Durante años se ha postulado que la dopamina (DA) liberada en el núcleo accumbens por neuronas tegmentales era el agente causal del refuerzo. Sin embargo, esta hipótesis es cada día más cuestionada y el refuerzo se subdivide en diversos procesos, sólo algunos de los cuales están relacionados con la DA. Utilizando el ratón como especie experimental, nos planteamos como objetivo comparar el papel de la DA en el refuerzo inducido por dos estímulos naturales diferentes. Utilizamos un reforzante ampliamente descrito, la sacarosa, frente un estímulo natural escasamente utilizado en neurobiología del comportamiento, las feromonas sexuales masculinas, que en la hembras de ratón induce una atracción innata reflejando sus propiedades reforzantes. Primero, y dado que el ratón es una especie relativamente poco estudiada desde el punto de vista anatómico, necesitamos un conocimiento detallado de la organización de las vías dopaminérgicas tegmento-telencefálicas y de sus conexiones aferentes. Por ello, los dos primeros capítulos de esta tesis constituyen estudios anatómicos detallados de los sistemas DAérgicos del ratón. En el Capítulo I realizamos una descripción de la distribución de las células y fibras dopaminérgicas en el encéfalo del ratón marcadas mediante la detección inumnohistoquimica de dos enzimas asociados a la dopamina, la hidroxilasa de tirosina y el transportador de dopamina. En el Capítulo II estudiamos las conexiones de el área ventral tegmental (VTA) mediante inyecciones de trazadores neuroanatómicos en el tegmento y en algunos de sus núcleos aferentes y eferentes. Estos capítulos nos han permitido identificar y caracterizar en el ratón la espiral tegmento-estriado-tegmental que describieron por primera vez en monos Haber et al. (2000), y postular hipótesis acerca del papel de los distintos componentes de la misma en el refuerzo. Los siguientes capítulos estudian el efecto de lesiones específicas DAérgicas de la vía tegmento-estriatal sobre comportamientos apetitivos relacionados con la obtención de una solución azucarada y de feromonas sexuales. En el Capítulo III analizamos el efecto de lesiones subtotales de las neuronas DAérgicas de la VTA sobre el consumo preferente de sacarosa (frente a agua) a largo plazo y sobre la exploración preferente de viruta ensuciada por macho en tests en que se enfrenta este estímulo con viruta limpia. Los resultados indican que estas lesiones disminuyen significativamente la ingesta preferente de sacarosa frente a agua durante 48 horas, mientras que no tienen efecto sobre la investigación preferente de viruta ensuciada por machos. Por último, en el Capítulo IV estudiamos el efecto de la denervación DAérgica de un centro clave de la espiral tegmento-estriado-tegmental, el cortex medial del núcleo accumbens, en la dinámica de la adquisición de los dos estímulos reforzantes, durante los primeros minutos en animales sin ninguna experiencia previa con los mismos. Los resultados de estos experimentos nos permiten entender mejor los importantes fenómenos de aprendizaje que ocurren en esta primera experiencia y su modulación por la dopamina. Mientras que las no tienen efectos apreciables en la dinámica lineal de exploración de feromonas frente a viruta limpia), provocan un retraso significativo en las respuestas de neofobia e ingesta preferente de una solución azucarada frente a agua. Nuestros resultados sugieren que los distintos estímulos reforzantes poseen sustratos anatómicos y neuroquímicos en los que la dopamina juega un papel claramente diferente. En cualquier caso, nuestros resultados apoyan los datos acumulados en los últimos años que la activación de la vía DAérgica tegmento-estriatal no es el fenómeno causal de la hedonia de los estímulos reforzantes, sea cual sea su naturaleza y el sistema sensorial que los detecte. / Reward is a complex psychological process that allows animals to modify their behaviour against profitable situations. Dopamine (DA) released in the nucleus accumbens by tegmental neurons was postulated as the cause of reward. But this hypothesis has been questioned and nowadays reward is parsed in several subprocesses. Using mice, our objectives were to compare the role of DA in reward induced by two different natural stimuli. A well-known reward, sucrose, against a sparsely-used, male-sexual pheromones. Those in female mice induce an innate attraction reflecting their rewarding properties. First, due to mice is anatomically a relatively not-studied species, we needed a detailed-knowledge of the organization of the dopaminergic tegmentum-telencephalic pathway and afferent connections. So, in the Chapter I we realized a description of the distribution of the dopaminergic cells and fibres in the mouse encephalon. In the Chapter II we studied the connections of the ventral tegmental area (VTA) with injections of tracers in the tegmentum and in some target nuclei. These chapters have identified and characterized in mice the tegmentum-striatum-tegmentum spiral described in monkeys by Haber et al. (2000), and postulate about a role of the different components of the spiral. In the Chapter III we analyzed the effect of lesions of the VTA-dopaminergic neurons in the preferent intake of sucrose against water during 48-h and the preferent exploration of male-used bedding against clean bedding. These lesions impair significatively the preferent intake of sucrose meanwhile they have no effect in the preferent exploration of male-used bedding. In the Chapter IV we study the effect of the DAergic denervation in the medial shell of the nucleus accumbens, in the dynamics of acquisition of both stimuli during the first experience. These lesions have no effect in the lineal dynamics of exploration of pheromones, but they delay neophobia and preferent intake of sucrose. That allows us to understand better the learning and DA-modulation that happens in this first experience Our results suggest that different rewarding stimuli have different anatomic and neurochemical substrates. Our results reinforce hypothesis that the activation of the DAergic tegmentum-striatum pathway is not the cause of hedony of rewarding stimuli.

Leptinotarsa decemlineata (escarabajo de la patata) es el insecto defoliador de patata de mayor importancia económica a nivel mundial, que también puede atacar otras plantas de interés económico como berenjena y tomate, y que ha desarrollado resistencia frente a un gran número de los insecticidas químicos utilizados para combatirlo. Las toxinas Cry de Bacillus thuringiensis, las cuales son altamente específicas para sus dianas e inocuas para los vertebrados, la gran mayoría de los invertebrados y las plantas, constituyen una herramienta de gran valor para el control de esta plaga, sin provocar efectos perjudiciales sobre el medio ambiente. En el presente trabajo hemos profundizado en el estudio del modo de acción de la toxina Cry3Aa de B. thuringiensis en L. decemlineata, centrándonos en los eventos que tienen lugar como consecuencia de su interacción con la membrana del epitelio intestinal. Hemos encontrado que la toxina Cry3Aa interactúa con proteínas localizadas tanto en los lipid rafts como fuera de estos microdominios de membrana, entre las que hemos identificado, por homología de secuencia, las proteínas prohibitina-1 y -2, RACK1, anexina, actina, y V-ATPasa, proteínas cuya interacción con Cry3Aa no había sido descrita, ni se habían previamente identificado en L. decemlineata. Como resultado de su interacción con la membrana del epitelio intestinal, la toxina Cry3Aa se proteoliza por proteasas asociadas a dicha membrana. La proteólisis tiene lugar por regiones expuestas del dominio III de Cry3Aa y es catalizada por cisteín proteasas de la familia de las intestaínas y por metaloproteasas probablemente de la familia de las ADAM. El reconocimiento de la toxina Cry3Aa por las metaloproteasas ADAM debe producirse a través de una secuencia localizada en el lazo 1 del dominio II. Mediante el análisis de la influencia de moduladores de la actividad proteolítica de metaloproteasas ADAM en la proteólisis de la toxina Cry3Aa, catalizada por vesículas de la membrana del borde en cepillo del epitelio intestinal, comprobamos que el compuesto extractor de colesterol MCD disminuye la proteólisis de la toxina y el inhibidor de calmodulina TFP produce su incremento. La unión de la proteína calmodulina a Cry3Aa impide la proteólisis de la toxina catalizada por las metaloproteasas ADAM asociadas a la membrana. Desde el punto de vista funcional, el procesado proteolítico de la toxina Cry3Aa catalizado por las metaloproteasas de tipo ADAM es necesario para su toxicidad en células disociadas del epitelio intestinal y en larvas de L. decemlineata. / The Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say) is an exceptionally destructive insect pest for potato, tomato, eggplant and other solanaceous crops, responsible of important economic losses in agriculture, which to date has developed resistance to a wide variety of synthetic chemical insecticides. Bacillus thuringiensis (Bt) Cry3Aa toxin based bioinsecticides, which are highly specific, safe for users and the environment, represent a viable alternative for the biological control of this important agricultural pest. In the present work we have deepened in the study of Bt Cry3Aa toxin mode of action in CPB, focusing in the analysis of Cry3Aa toxin interaction with CPB midgut epithelium membrane. We have found that Cry3Aa toxin binds to both lipid rafts and non-rafts membrane associated proteins, among them, we have identified by sequence homology the proteins prohibitins-1 and -2, RACK1, annexin, actin and V-ATPase, which interaction with Cry3Aa toxin or identification in CPB, have not been previously reported. As a result of Cry3Aa interaction with CPB midgut epithelium, the toxin is proteolyzed by membrane associated proteases. Cry3Aa toxin proteolysis takes place in domain III exposed regions and it is catalyzed by digestive cysteine proteases intestains and metalloproteases probably belonging to the ADAM family. CPB ADAM like metalloproteases must recognize Cry3Aa toxin by a region located in loop I of domain II. The analysis of the influence of modulators of ADAM metalloprotease activity in Cry3Aa proteolysis, catalyzed by midgut brush border membrane vesicles, shows that the cholesterol extracting compound MCD decreases Cry3Aa proteolysis and the calmodulin inhibitor TFP enhances proteolysis. Cry3Aa binding to calmodulin prevents toxin proteolysis catalyzed by CPB ADAM like metalloproteases. From a functional standpoint, Cry3Aa toxin proteolysis catalyzed by CPB ADAM like metalloproteases is a key event in Cry3Aa toxicity against CPB larvae and dissociated midgut epithelium cells.

Beta defensins (DEFB) at the 8p23.1 genomic location are multifunctional secreted short peptides that have antibacterial and antiviral action in many species and possess immune cell signal activity, constituting a link between innate and adaptive immunity. In humans, the β-defensin region is known to be copy number variable (CNV) and contains seven genes repeated as a block, with a diploid copy number between 1 and 12. This thesis shall explore the structural variability of the β-defensin CNV region; compare and contrast the different methods used for calling DEFB CNVs and investigate the role of CNVs of DEFB in various diseases. One of its aims is to also develop a model system to investigate if DEFB expression levels differ with CN in response to treatment with Pneumolysin by using Normal Human Bronchial Epithelial (NHBE) cells. Results from this thesis confirm that the DEFB CNV region is 322kb in length, with a polymorphic inversion that occurs at a prevalence of 30% at the 8p23.1 genomic location that is independent of the DEFB CN. Paralogue Ratio Test (PRT) proved to be the best method of genotyping DEFB CNV especially in larger cohorts. In addition, work from this thesis also founded the basis of developing an in vitro model system to investigate whether DEFB expression levels differ with CN in response to treatment with pneumolysin by using Normal Human Bronchial Epithelial (NHBE) cells. As far as case/control and cohort studies are concerned, results from this thesis show that DEFB CN is not associated with lung function in the general population and has no effect on patients with COPD and Asthma, nor does it support previous results that present an association between HIV viral load and DEFB CN. DEFB CN was also found not to be associated with recurrent UTIs in VUR patients, nor with hypertension. Data suggested that DEFB CN might be associated with BMI but this has not been reproduced in a smaller cohort.

Theoretical anthropology tries to develop models of human biology and culture. In this thesis, we investigate how different computational models from theoretical biology can be applied to evolutionary anthropology. We study two different types of models, applying them to two different sub-fields of evolutionary anthropology, and highlighting alternative choices in their construction. On the one hand, we observe that the evolutionary simulations are composed of three main components: an updating rule, a game and a population structure. We find that the updating rule can alter the qualitative and quantitative evolutionary outcome of a model. A dominant language is more resilient to learning errors and more frequent when selection primarily weeds out maladapted individuals, instead of promoting well-adapted ones. We study the evolution of cooperation and institutional punishment. Group selection can support cooperation, even when implemented through the selection of individual agents migrating between communities at different rates. Institutional punishment on the other hand is highly complex and cannot arise from simpler strategies in either wellmixed or community-structured populations. On the other hand, Bayesian inference models used for linguistic phylogenies can incorporate highly correlated typological information, without a priori knowledge about the underlying linguistic universals. While close in subject, models in theoretical biology and profound anthropological expertise express all but disjoint theories in terms of scope and complexity. This thesis acknowledges this challenge and contributes to bridging the gap.

In most fields of technology and science, the exponential increase of available data is an apparent trend. In genetics, the main contributor to this trend is the improving efficiency of sequencing technologies. While the Human Genome project focused on assembling a single reference sequence not long ago, now there are aims to sequence million genomes in upcoming projects. The consequent computational challenge is being able to utilise this wealth of data, which requires the development of sufficiently powerful methods for analysis. However, the speed of transistor-based computing processors has recently hit a power ceiling and developers can no longer rely on hardware improvements automatically providing performance improvements in software directly. The result is that analysis methods are failing to keep up with the speed of data generation, and at this age of exponential data explosion it is becoming critical to find any solution for improving the performance of statistical methods. One traditional approach is to apply approximations - often trading the quality of results for response time. Another approach is to achieve algorithmic optimisations for existing methods without sacrificing results. Unfortunately, the possibilities for purely algorithmic optimisations often tend to be limited. A third approach is to attempt to harness the computational power of the presently re-emerging field of parallel computing. While the theoretical performance of parallel platforms roughly follows Moore's law, exploiting the power of parallelisms requires significant effort during development and may not even be possible in certain applications. This work attempts to explore avenues for achieving high performance for Hidden Markov Models (HMMs) and HMM applications in population genetics. The second chapter of this thesis introduces a single-locus variant of the IMPUTE2 method for calling and phasing genotype variants based on genotype likelihood data. This method uses both approximations and algorithmic optimisations and achieves performance improvements without a considerable drop in accuracy. It is also aimed to be highly parallelisable. The third chapter presents GPGPU-focused parallelisation methods over the statespace for HMM algorithms specifically under the Li and Stephens model, which is a widely and successfully used approximation of the coalescent. Practical experiments show ×200-×6000 times acceleration with a CUDA implementation of the popular Chromopainter method, which is based on the Li and Stephens model. The last chapter explores the theoretical possibility of parallelising HMM algorithms across blocks of observations (inspired by but not limited to methods used in genetics). A novel view and derivation is presented for block parallelism, along with accompanying analyses of applicability and relevance. Performance analysis results indicate that the application of block-parallelism is expected to be highly relevant for most large-scale HMM applications on present-day computing platforms, while block-parallelism may become a necessity for utilising the improving power of parallel hardware in the close future.

In the Caribbean region, Varronia rupicola (Boraginaceae) is a medium to large, woody shrub endemic to the Puerto Rican Bank where it is threatened with extinction due to its limited area of occupancy, small populations and on-going threats. The greatest of these is currently loss of suitable habitat through development and degradation. These are caused by human activities that are expected to continue and possibly worsen. The species is also threatened by sea level rise and drought as well as natural disasters, particularly hurricanes and tsunamis. Combined, the effects of anthropogenic and climate change induced threats could push the species to extinction over the coming century. Through interrogation of the findings of cyto-, phylo- and population genetic as well as biogeographical research, it is clear that V. rupicola is a distinct species that is endemic to the islands of Puerto Rico, Vieques and Anegada where five populations were detected. The species has lost genetic diversity in the wild through a reduction in population size with allelic diversity proportional to the size of the population. The five populations were found to have lower than expected levels of heterozygosity as well as significant genetic differentiation and inbreeding. Varronia rupicola plants were found in an extremely limited area of intact habitat (<90 km2) overlying substrates that cover <200 km2 across the three islands. Protected areas contain less than a third (<30 km2) of the remaining intact habitat that supports the species and established ex-situ collections capture less than half of the private alleles found in the wild. An integrated approach to the species conservation is needed to maximise genetic diversity and potentiality allow adaptation of V. rupicola to environmental change and new threats.

No description available.