Three motAB stator gene products in Bdellovibrio bacteriovorus contribute to motility of a single flagellum during predatory and prey-independent growth

The predatory bacterium Bdellovibrio bacteriovorus uses flagellar motility to locate regions rich in Gram-negative prey bacteria, colliding and attaching to prey and then ceasing flagellar motility. Prey are then invaded to form a "bdelloplast" in a type IV pilus-dependent process, and prey contents are digested, allowing Bdellovibrio growth and septation. After septation, Bdellovibrio flagellar motility resumes inside the prey bdelloplast prior to its lysis and escape of Bdellovibrio progeny. Bdellovibrio can also grow slowly outside prey as long flagellate host-independent (HI) cells, cultured on peptone-rich media. The B. bacteriovorus HD100 genome encodes three pairs of MotAB flagellar motor proteins, each of which could potentially form an inner membrane ion channel, interact with the FliG flagellar rotor ring, and produce flagellar rotation. In 2004, Flannagan and coworkers (R. S. Flannagan, M. A. Valvano, and S. F. Koval, Microbiology 150:649-656, 2004) used antisense RNA and green fluorescent protein (GFP) expression to downregulate a single Bdellovibrio motA gene and reported slowed release from the bdelloplast and altered motility of the progeny. Here we inactivated each pair of motAB genes and found that each pair contributes to motility, both predatorily, inside the bdelloplast and during HI growth; however, each pair was dispensable, and deletion of no pair abolished motility totally. Driving-ion studies with phenamil, carbonyl cyanide m-chlorophenylhydrazone (CCCP), and different pH and sodium conditions indicated that all Mot pairs are proton driven, although the sequence similarities of each Mot pair suggests that some may originate from halophilic species. Thus, Bdellovibrio is a "dedicated motorist," retaining and expressing three pairs of mot genes.

A predatory patchwork:membrane and surface structures of Bdellovibrio bacteriovorus

Predatory Bdellovibrio bacteriovorus bacteria are remarkable in that they attach to, penetrate and digest other Gram-negative bacteria, living and replicating within them until all resources are exhausted, when they escape the prey ghost to invade fresh prey. Remarkable remodeling of both predator and prey cell occurs during this process to allow the Bdellovibrio to exploit the intracellular niche they have worked so hard to enter, keeping the prey "bdelloplast" intact until the end of predatory growth. If one views motile non-predatory bacteria in a light microscope, one is immediately struck by how rare it is for bacteria to collide. This highlights how the cell surface of Bdellovibrio must be specialized and adapted to allow productive collisions and further to allow entry into the prey periplasm and subsequent secretion of hydrolytic enzymes to digest it. Bdellovibrio can, however, also be made to grow artificially without prey; thus, they have a large genome containing both predatory genes and genes for saprophytic heterotrophic growth. Thus, the membrane and outer surface layers are a patchwork of proteins encompassing not only those that have a sole purpose in heterotrophic growth but also many more that are specialized or employed to attach to, enter, remodel, kill and ultimately digest prey cells. There is much that is as yet not understood, but molecular genetic and post-genomic approaches to microbial physiology have enhanced the pioneering biochemical work of four decades ago in characterizing some of the key events and surface protein requirements for prey attack.

A spatio-temporal contrast of the predatory impact of an invasive freshwater crustacean

Aim: Impacts of invasive species may vary across invasion gradients, owing to trait-based sorting of individuals through dispersal: those aggregating at invasion fronts may be more aggressive and voracious. We examine, in the field and laboratory, variation in the predatory impacts of an invasive Ponto-Caspian crustacean Hemimysis anomala G.O. Sars, 1907 at two sites along a spatio-temporal gradient of invasion.

Location: Republic of Ireland.

Methods: We used reciprocal transplant field-deployed mesocosms to compare predation rates of invasion front and well-established H. anomala on natural zooplankton assemblages. In the laboratory, we measured the functional response (relationship between predation rate and prey supply) of H. anomala from both sites, for a per capita mechanistic comparison of predation efficiency. We also assessed prey selectivity of H. anomala in the mesocosm experiments to further compare feeding behaviour. Finally, we used a correlative approach to assess the community impact of H. anomala across sites, including a nearby uninvaded site, by comparing zooplankton diversities and densities.

Results: Invasion front H. anomala had higher predation rates than well-established H. anomala at high in situ zooplankton densities. Invasion front H. anomala also had higher functional responses - in particular showing higher 'attack rates' - indicating a heightened ability to locate and capture prey. Prey selectivity was consistent across the spatio-temporal contrast, with positive selection for cladocerans. Zooplankton diversity and density declined with time since H. anomala invasion, both being maximal at the uninvaded site.

Main conclusions: Our study, for the first time, (1) reveals differences in predatory per capita effects and associated behavioural traits between two sites along a spatio-temporal invasion gradient and (2) shows a negative community-level impact of the invasive H. anomala in natural water bodies. Further spatio-temporal comparisons of predatory per capita effects of invaders are needed to assess the generality of these results.

Influence of environmental variables on the predatory sucess of the iberian wolf in the north of Portugal

Tese de mestrado em Biologia da Conservação, apresentada à Universidade de Lisboa, através da Faculdade de Ciências, 2016

Trophic ecology of jumbo squid and predatory fishes in the Northern Humboldt Current System

This work provides a contribution to a better understanding of the trophic ecology of important predators in the Northern Humboldt Current System, the jack mackerel (Trachurus murphyi), the chub mackerel (Scomber japonicus) and the jumbo squid (Dosidicus gigas) by the characterization of the highly variable feeding patterns of these species at different spatiotemporal scales. We provided new knowledge on the comparative trophic behaviour of these species, defined as opportunistic in previous investigations. For that purpose we applied a variety of statistical methods to an extensive dataset of 27,188 non-empty stomachs. We defined the spatial organization of the forage fauna of these predators and documented changes in prey composition according to predators’ size and spatiotemporal features of environment. Our results highligh the key role played by the dissolved oxygen. We also deciphered an important paradox on the jumbo squid diet: why do they hardly forage on the huge anchovy (Engraulis ringens) biomass distributed of coastal Peru? We showed that the shallow oxygen minimum zone present off coastal Peru could hamper the co-occurrence of jumbo squids and anchovies. In addition, we proposed a conceptual model on jumbo squid trophic ecology including the ontogenetic cycle, oxygen and prey availability. Moreover we showed that the trophic behaviour of jack mackerel and chub mackerel is adapted to forage on more accessible species such as for example the squat lobster Pleurocondes monodon and Zoea larvae. Besides, both predators present a trophic overlap. But jack mackerel was not as oracious as chub mackerel, contradictorily to what was observed by others authors. Fish diet presented a high spatiotemporal variability, and the shelf break appeared as a strong biogeographical frontier. Diet composition of our fish predators was not necessarily a consistent indicator of changes in prey biomass. El Niño events had a weak effect on the stomach fullness and diet composition of chub mackerel and jack mackerel. Moreover, decadal changes in diet diversity challenged the classic paradigm of positive correlation between species richness and temperature. Finally, the global patterns that we described in this work, illustrated the opportunistic foraging behaviour, life strategies and the high degree of plasticity of these species. Such behaviour allows adaptation to changes in the environment.

Protect yourself from Predatory Publishers: Tips for staying safe in Scholarly Publishing

Presented at Brock Library Spring Symposium 2015: What's really going on?

Las voces del silencio : una comunicaci??n sin l??mites

El libro incorpora la sistematicidad de un manual te??rico-pr??ctico sobre Comunicaci??n Aumentativa/ Alternativa y la sinceridad de un testimonio apoyado en la dilatada y comprometida experiencia profesional de la autora. En la primera parte del libro se puede encontrar una aproximaci??n te??rica al tema de la Comunicaci??n Aumentativa/ Alternativa junto a la experiencia llevada a cabo con usuarios de diferentes sistemas de Comunicaci??n A/A. En la segunda parte del libro se exponen una serie de casos pr??cticos apoyados en informes de alumnos usuarios de Bliss y SPC, Bimodal, Lenguaje de Signos, Schaeffer y la posibilidad de simultanear varios de estos sistemas en el caso de alumnos gravemente afectados. En la tercera parte la autora se dedica a reflexionar sobre su propia experiencia.

Passejada per les llegendes de Palma : itineraris pels mites, les llegendes, les curiositats, les anècdotes i els detalls de la Ciutat de Mallorca. 'Paseo por las leyendas de Palma : itinerarios por los mitos, las leyendas, las curiosidades, las anécdotas y los detalles de la Ciudad de Mallorca'.

Resumen tomado de la publicación

Mites socials en superdotació. 'Mitos sociales en superdotación'.

Resumen de la revista en catalán

Mites i diversitat lingüística i cultural. 'Mitos y diversidad lingüística y cultural'.

Resumen tomado de la publicación en catalán. Este artículo forma parte del monográfico 'Aprendre llengua en una societat multilingüe'

Educació : mites, dualitats i confusions. 'Educación : mitos, dualidades y confusiones'.

Reflexiona sobre cuestiones que expresan actitudes, orientación de la práctica y de la relación educativa. Se defiende que hay que cambiar de cultura educativa, hacia una que integre y comprometa a todo el mundo en esta tarea social, ya que todo el mundo es responsable de la educación de los niños y los jóvenes, y hacia una educación que dé prioridad a la formación de la persona, que eduque las emociones.

La nova agenda educativa global : l??mits i oportunitats. 'La nueva agenda educativa global : l??mites y oportunidades'

Resumen basado en el de la autora

Mites i realitats de la prevenció de les drogodependències (o de com avançar en l'eficàcia de la prevenció). 'Mitos y realidades de la prevención de las drogodependencias (o de como avanzar en la eficacia de la prevención)'.

En este artículo se plantea una reflexión sobre la problemática de la prevención de las drogodependencias, sobre los mitos de la misma, pero, también y sobre todo, sobre su realidad. Se realiza un breve análisis sobre la realidad de la prevención de las drogas en España. Finalmente, se dan una serie de orientaciones metodológicas para diseñar programas de prevención desde la dimensión de su eficacia.

Coeducació i docència en femení : estereotips, mites i valors. 'Coeducación y docencia en femenino : estereotipos, mitos y valores'.

Resumen basado en el de la publicación. Monográfico con el título: 'Dones i educació'