Search results for "Adapta"
showing 10 items of 1961 documents
Memantine does not block antiaggressive effects of morphine in mice.
2002
The action of the noncompetitive N-methyl-D-aspartate (NMDA) receptor blocker memantine (5, 10, 20 and 40 mg/kg) was evaluated during social encounters in mice. Although a dose-dependent increase in locomotion was observed, only with the highest dose did it reach statistical significance. Aggressive behavior was decreased with 20 and 40 mg/kg of memantine, social contacts being increased only with 20 mg/kg. Subsequently, the effect of these memantine doses on the antiaggressive actions of morphine (10 mg/kg) was evaluated. None of the doses affected the antiaggressive action of morphine. As memantine administration produced an antiaggressive effect only at doses that affected locomotion, it…
Bet-hedging in diapausing egg hatching of temporary rotifer populations - A review of models and new insights
2014
Habitat unpredictability is a local adaptation factor shaping life-history traits in rotifer populations. It may select for the evolution of bet-hedging through risk-spreading strategies in diapausing egg hatching. This means that a fraction of diapausing eggs in wild populations do not hatch even when the conditions are favorable for population growth. Thus, there is a remaining fraction of viable diapausing eggs standing in the sediments for longer periods. According to theory, it is expected that the incidence of bet-hedging strategies for diapausing egg hatching will be higher in more uncertain habitats. Here, we review the major predictions derived from theoretical models applied to th…
From foes to friends: Viral infections expand the limits of host phenotypic plasticity
2020
Phenotypic plasticity enables organisms to survive in the face of unpredictable environmental stress. Intimately related to the notion of phenotypic plasticity is the concept of the reaction norm that places phenotypic plasticity in the context of a genotype-specific response to environmental gradients. Whether reaction norms themselves evolve and which factors might affect their shape has been the object of intense debates among evolutionary biologists along the years. Since their discovery, viruses have been considered as pathogens. However, new viromic techniques and a shift in conceptual paradigms are showing that viruses are mostly non-pathogenic ubiquitous entities. Recent studies hav…
Do avian predators select for seasonal polyphenism in the European map butterfly Araschnia levana (Lepidoptera: Nymphalidae)?
2012
Seasonal polyphenism in animal colour patterns indicates that temporal variation in selection pressures maintains phenotypic plasticity. Spring generation of the polyphenic European map butterfly Araschnia levana has an orange–black fritillary-like pattern whilst individuals of the summer generation are black with white bands across the wings. What selects for the colour difference is unknown. Because predation is a major selection pressure for insect coloration, we first tested whether map butterfly coloration could have a warning function (i.e. whether the butterflies are unpalatable to birds). In a following field experiment with butterfly dummies we tested whether the spring form is bet…
EctoparasiticArgulus coregoni(Crustacea: Branchiura) hedge their bets - studies on egg hatching dynamics
2004
Unpredictability in the temporal availability of susceptible hosts is likely to act as a selection pressure affecting the life history strategies of parasites. In highly variable environments the future of the lineage can be secured by spreading the risk, for example, by producing descendants that differ in their timing of emergence. Counter to this, in predictable environments a single “best-adapted” phenotype is expected. We asked whether ectoparasitic Argulus coregoni egg hatching pattern can be explained as a genetically canalized individual trait; an instance of phenotypic plasticity or bet-hedging. We collected egg clutches laid by individual A. coregoni females in early and late repr…
In Vitro Analysis of the Two-Component System MtrB-MtrA from Corynebacterium glutamicum▿ †
2007
ABSTRACT The two-component system MtrBA is involved in the osmostress response of Corynebacterium glutamicum . MtrB was reconstituted in a functionally active form in liposomes and showed autophosphorylation and phosphatase activity. In proteoliposomes, MtrB activity was stimulated by monovalent cations used by many osmosensors for the detection of hypertonicity. Although MtrB was activated by monovalent cations, they lead in vitro to a general stabilization of histidine kinases and do not represent the stimulus for MtrB to sense hyperosmotic stress.
Evidences of adaptive traits to rocky substrates undermine paradigm of habitat preference of the Mediterranean seagrass Posidonia oceanica
2015
AbstractPosidonia oceanica meadows are acknowledged as one of the most valuable ecosystems of the Mediterranean Sea. P. oceanica has been historically described as a species typically growing on mobile substrates whose development requires precursor communities. Here we document for the first time the extensive presence of sticky hairs covering P. oceanica seedling roots. Adhesive root hairs allow the seedlings to firmly anchor to rocky substrates with anchorage strength values up to 5.23 N, regardless of the presence of algal cover and to colonise bare rock without the need for precursor assemblages to facilitate settlement. Adhesive root hairs are a morphological trait common on plants li…
The ⊥-Illusion Is Not a T-Illusion
2020
Variants of the capital Latin letter T were prepared with the straight strokes replaced by J-, C-, or S-curves, mimicking handwritten Ts. These were used to test the hypothesis that the overestimation of the length of the T&rsquo
Small field motion detection in goldfish is red-green color blind and mediated by the M-cone type
2007
Large field motion detection in goldfish, measured in the optomotor response, is based on the L-cone type, and is therefore color-blind (Schaerer & Neumeyer, 1996). In experiments using a two-choice training procedure, we investigated now whether the same holds for the detection of a small moving object (size: 8 mm diameter; velocity: 7 cm/s). In initial experiments, we found that goldfish did not discriminate between a moving and a stationary stimulus, obviously not taking attention to the cue “moving.” Therefore, random dot patterns were used in which the stimulus was visible only when moving. Using black and white random dot patterns with variable contrast between 0.2 and 1, we found…
Turing Patterns in Nonlinear Optics
2000
The phenomenon of pattern formation in nonlinear optical resonators is commonly related to an off-resonance excitation mechanism, where patterns occur due to mismatch between the excitation and resonance frequency. In this paper we show that the patterns in nonlinear optics can also occur due to the interplay between diffractions of coupled field components. The reported mechanism is analogous to that of local activation and lateral inhibition found in reaction-diffusion systems by Turing. We study concretely the degenerate optical parametric oscillators. A local activator-lateral inhibitor mechanism is responsible for generation of Turing patterns in form of hexagons.