A mosca-da-azeitona, Bactrocera oleae (Gmelin), no Planalto Mirandês: ciclo biológico e importância económica.

Em Portugal o olival para produção de azeitona de mesa representa 4.0% da superfície olivícola. Trás-os-Montes concentra aproximadamente metade da área nacional e mais de 55% da produção. Um dos principais entraves a produção diz respeito aos prejuízos de natureza quantitativa e qualitativa. provocados peles inimigos da cultura. Entre estes inimigos assume particular relevo a mosca-da-azeitona, Bactrocera oleae (Gmelin) que constitui a praga chave da cultura no conjunto dos países da bacia do Mediterrâneo. Com 0 presente estudo pretendeu-se contribuir para o conhecimento do cicio biológico da mosca-da-azeitona, Bactrocera oleae (Gmelin), e sua importância económica em azeitona de mesa na região do Planalto Mirandês

Ciclo biológico e estragos associados a monosteira, Monosteira unicostata (Mulsant & Rey, 1852), em amendoeira, no Planalto Mirandês

A monosteira, Monostelro unicostata (Mulsant & Rey, 1852), e considerada uma praga importante da amendoeira. Contudo, em Portugal, são escassos os conhecimentos acerca da sua biologia e dos estragos que ocasiona. Neste sentido, com o presente trabalho pretendeu-se par um lado estudar o cicio biológico do insecto em amendoeira no Planalto Mirandês, e por outro lado proceder a uma avaliação dos estraagos causados pela praga. O trabalho decorreu em 2007 e 2008 num amendoal localizado em Vilarinho dos Galegos (Mogadouro) onde, com periodicidade semanal ou quinzenal, se procedeu a recolha de 20 folhas em 20 árvores para observação (i) da existência de ovos, ninfas e adultos de monosteira e (ii) do numero de folhas com estragos visíveis. Paralelamente, e com periodicidade aproximadamente quinzenal foi realizada a técnica de pancadas em 25 arvores escolhidas aleatoriamente na parcela para quantificação dos adultos da praga

Desxifrant mecanismes enzimàtics per mitjà d'eines computacionals: implicacions biotecnològiques en l'estudi de glicosidases

El creixement de la glicòmica (camp anàleg al de la genòmica o la proteòmica però centrat en glicòsids) i el desenvolupament de tests de diagnòstic, vacunes i nous fàrmacs basats en carbohidrats es veuen afectats per la falta de mètodes eficients per a la seva producció. La síntesi enzimàtica, caracteritzada per la seva gran estereo- i regioselectivitat duta a terme en condicions suaus, representa una encoratjadora solució per resoldre aquest problema. En aquest aspecte, les glicosilhidrolases (GH) amb retenció de configuració tenen un gran potencial per ser redissenyades per sintetitzar carbohidrats per transglicosidació. La conversió de glicosidases (GH) a transglicosidases (TG), és a dir, d'enzims que hidrolitzen carbohidrats a enzims que els sintetitzen, ha estat molt estudiada en els darrers anys. Tot i així, la falta d'estructures d'enzims i el desconeixement dels detalls dels mecanismes de reacció limiten el disseny racional de TG. En aquest article exposem com la química teòrica i les simulacions de dinàmica molecular de primers principis poden aportar el coneixement fonamental per a la producció d'aquestes valuoses variants enzimàtiques

Ecological characterization of wild grapevine habitats focused on arbuscular mycorrhizal symbiosis

The European wild grapevine, Vitis vinifera L. ssp. sylvestris (Gmelin) Hegi, is cited as a dioecious relative of cultivated vines, so it can play an important role as phytogenetic resource. There is a lack on the knowledge about the susceptibility of wild grapevine to arbuscular mycorrhizal (AM) association. In consequence, the aim of the present work is to confirm the presence of arbuscular mycorrhizal fungi (AM) in the wild grapevine rhizosphere spread in different kinds of soils from 18 wild populations from Spain and France. On the other hand, the accompanying flora, the edaphic characteristics and the presence of parasitic organisms on vines were also determined. The spore density of mycorrhizal fungi in the rhizosphere of the selected plants was relatively low. However, the diversity of mycorrhizal fungi was quite high. The taxonomic diversity of AM observed is 56 taxa, 15 of which were identified to species and 41 to genus. Some morphotypes do not correspond to any of the species described up to now. Results indicate the important quality and ecological value in the sites studied and, in consequence, the necessity of their preservation

A new view of k-essence

K-essence models, relying on scalar fields with non-canonical kinetic terms, have been proposed as an alternative to quintessence in explaining the observed acceleration of the Universe. We consider the use of field redefinitions to cast k-essence in a more familiar form. While k-essence models cannot in general be rewritten in the form of quintessence models, we show that in certain dynamical regimes an equivalence can be made, which in particular can shed light on the tracking behaviour of k-essence. In several cases, k-essence cannot be observationally distinguished from quintessence using the homogeneous evolution, though there may be small effects on the perturbation spectrum. We make a detailed analysis of two k-essence models from the literature and comment on the nature of the fine tuning arising in the models.Comment: 7 pages RevTeX4 file with four figures incorporate

K-essence and the coincidence problem

K-essence has been proposed as a possible means of explaining the coincidence problem of the Universe beginning to accelerate only at the present epoch. We carry out a comprehensive dynamical systems analysis of the k-essence models given so far in the literature. We numerically study the basin of attraction of the tracker solutions and we highlight the behaviour of the field close to sound speed divergences. We find that, when written in terms of parameters with a simple dynamical interpretation, the basins of attraction represent only a small region of the phase space.Comment: 5 pages RevTeX4 file with two figures incorporated. Minor changes to match PRD accepted versio

Condensation in randomly perturbed zero-range processes

The zero-range process is a stochastic interacting particle system that exhibits a condensation transition under certain conditions on the dynamics. It has recently been found that a small perturbation of a generic class of jump rates leads to a drastic change of the phase diagram and prevents condensation in an extended parameter range. We complement this study with rigorous results on a finite critical density and quenched free energy in the thermodynamic limit, as well as quantitative heuristic results for small and large noise which are supported by detailed simulation data. While our new results support the initial findings, they also shed new light on the actual (limited) relevance in large finite systems, which we discuss via fundamental diagrams obtained from exact numerics for finite systems.Comment: 18 pages, 6 figure

Selective derivatization of N-terminal cysteines using cyclopentenediones

The outcome of the Michael-type reaction between thiols and 2,2-disubstituted cyclopentenediones varies depending on the thiol. Stable compounds with two fused rings were formed upon reaction with 1,2-aminothiols (such as N-terminal cysteines in peptides). Other thiols gave reversibly Michael-type adducts that were in equilibrium with the starting materials. This differential reactivity allows differently placed cysteines to be distinguished and has been exploited to prepare bioconjugates incorporating two or three different moieties