Search results for "IMM"
showing 10 items of 18201 documents
Kindness to the final host and vice versa: A trend for parasites providing easy prey?
2019
Traditionally the “extended phenotype” concept refers to parasites that manipulate host phenotype to increase parasite fitness. This includes parasites that render intermediate hosts more susceptible to predation by final hosts. We explore here the proposition that an evolutionary driver in such cases is the energetic benefit to the final host, in addition to increased parasite fitness. We will review some well-established host-manipulation models, where such a scenario seems likely. One example is provided by the protozoan Toxoplasma gondii, which conspicuously impairs predator avoidance in rodents. Pathologies in humans that acquire T. gondii are known, but infection in adult feline defin…
Arabidopsis RCD1 coordinates chloroplast and mitochondrial functions through interaction with ANAC transcription factors
2019
Reactive oxygen species (ROS)-dependent signaling pathways from chloroplasts and mitochondria merge at the nuclear protein RADICAL-INDUCED CELL DEATH1 (RCD1). RCD1 interacts in vivo and suppresses the activity of the transcription factors ANAC013 and ANAC017, which mediate a ROS-related retrograde signal originating from mitochondrial complex III. Inactivation of RCD1 leads to increased expression of mitochondrial dysfunction stimulon (MDS) genes regulated by ANAC013 and ANAC017. Accumulating MDS gene products, including alternative oxidases (AOXs), affect redox status of the chloroplasts, leading to changes in chloroplast ROS processing and increased protection of photosynthetic apparatus.…
Calcium—Nutrient and Messenger
2019
Calcium is an essential element needed for growth and development of plants under both non-stressed and stress conditions. It thereby fulfills a dual function, being not only an important factor for cell wall and membrane stability, but also serving as a second messenger in many developmental and physiological processes, including the response of plants to biotic stress. The perception of non-self hereby induces an influx of calcium ions (Ca2+) into the cytosol, which is decoded into downstream responses ultimately leading to defense. Maintaining intracellular Ca2+ homeostasis is crucial for the ability to generate this signal. This review will describe the current knowledge of the mechanis…
An ancestral allele of grapevine transcription factor MYB14 promotes plant defence
2016
Highlight The molecular mechanisms underlying the elevated inducibility of stilbene in pathogen-resistant Vitis sylvestris can be explained by the increased inducibility of the MYB14 promoter.
Erwinia carotovora subsp. odorifera subsp.nov., associated with odorous soft rot of chicory (Cichorium intybus L.)
1992
Eleven strains of Erwinia carotovora that were isolated mainly, but not exclusively, from slimy rot of witloof chicory and were previously designated “atypical” E. carotovora subsp. atroseptica strains were characterized and compared with strains of E. carotovora subsp. carotovora, E. carotovora subsp. atroseptica, and Erwinia chrysanthemi (including the type strains). The 11 atypical E. carotovora subsp. atroseptica strains produced a typical bananalike odor when they were inoculated onto witloof chicory leaves. DNA-DNA homology experiments, biochemical tests, tests to determine carbon utilization patterns, and tests to identify the volatile metabolites produced from rotting witloofs were …
Ants medicate to fight disease
2015
Parasites are ubiquitous, and the ability to defend against these is of paramount importance. One way to fight diseases is self-medication, which occurs when an organism consumes biologically active compounds to clear, inhibit, or alleviate disease symptoms. Here, we show for the first time that ants selectively consume harmful substances (reactive oxygen species, ROS) upon exposure to a fungal pathogen, yet avoid these in the absence of infection. This increased intake of ROS, while harmful to healthy ants, leads to higher survival of exposed ants. The fact that ingestion of this substance carries a fitness cost in the absence of pathogens rules out compensatory diet choice as the mechanis…
Acclimation capacity and rate change through life in the zooplankton Daphnia
2020
When a change in the environment occurs, organisms can maintain an optimal phenotypic state via plastic, reversible changes to their phenotypes. These adjustments, when occurring within a generation, are described as the process of acclimation. While acclimation has been studied for more than half a century, global environmental change has stimulated renewed interest in quantifying variation in the rate and capacity with which this process occurs, particularly among ectothermic organisms. Yet, despite the likely ecological importance of acclimation capacity and rate, how these traits change throughout life among members of the same species is largely unstudied. Here we investigate these re…
Immunological detection of tonoplast polypeptides in the plasma membrane of pea cotyledons
1996
The tonoplast is usually characterized by the presence of two electrogenic proton pumps: a vacuolartype H+-ATPase and a pyrophosphatase, as well as a putative water-channel-forming protein (γ-TIP). Using a post-embedding immunogold labelling technique, we have detected the presence of these transport-protein complexes not only in the tonoplast, but also in the plasma membrane and trans Golgi elements of maturing pea (Pisum sativum L.) cotyledons. These ultrastructural observations are supported by Western blotting with highly purified plasma-membrane fractions. In contrast to the vacuolar-type H+-ATPase, whose activity was not measurable, considerable pyrophosphatase activity was detected i…
Sex in space: population dynamic consequences
1999
Sex, so important in the reproduction of bigametic species, is nonetheless often ignored in explorations of the dynamics of populations. Using a growth model of dispersal-coupled populations we can keep track of fluctuations in numbers of females and males. The sexes may differ from each other in their ability to disperse and their sensitivity to population density. As a further complication, the breeding system is either monogamous or polygamous. We use the harmonic mean birth function to account for sex-ratio-dependent population growth in a Moran–Ricker population renewal process. Incorporating the spatial dimension stabilizes the dynamics of populations with monogamy as the breeding sys…
Measured immunocompetence relates to the proportion of dead parasites in a wild roach population
2009
Summary 1. Although various methods are used to measure immunocompetence, their relationship with the actual parasite clearance or parasite load is seldom demonstrated in natural systems. 2. We combined nine measures of immune function using principal component analysis (PCA), and examined the relationship of the collective measures with (i) the proportion of parasites killed by the host, (ii) the burden of several parasite species and (iii) a viral disease in a wild population of the roach, Rutilus rutilus. We also studied if these variables were associated with the concentration of steroids (testosterone and oestradiol). 3. Most significant correlations between the loads of ecto- and gill…