Seed germination and seedling allogamy in Rosmarinus officinalis: the costs of inbreeding.

Self-pollination by geitonogamy is likely in self-compatible plants that simultaneously expose a large number of flowers to pollinators. However, progeny of these plants is often highly allogamous. Although mechanisms to increase cross-pollination have been identified and studied, their relative importance has rarely been addressed simultaneously in plant populations. We used Rosmarinus officinalis to explore factors that influence the probability of self-fertilisation due to geitonogamy or that purge its consequences, focusing on their effects on seed germination and allogamy rate. We experimentally tested the effect of geitonogamy on the proportion of filled seeds and how it influences germination rate. During two field seasons, we studied how life history and flowering traits of individuals influence seed germination and allogamy rates of their progeny in wild populations at the extremes of the altitudinal range. The traits considered were plant size, population density, duration of the flowering season, number of open flowers, flowering synchrony among individuals within populations and proportion of male-sterile flowers. We found that most seeds obtained experimentally from self-pollination were apparently healthy but empty, and that the proportion of filled seeds drove the differences in germination rate between self- and cross-pollination experiments. Plants from wild populations consistently had low germination rate and high rate of allogamy, as determined with microsatellites. Germination rate related positively to the length of the flowering season, flowering synchrony and the ratio of male-sterile flowers, whereas the rate of allogamous seedlings was positively related only to the ratio of male-sterile flowers. Rosemary plants purge most of the inbreeding caused by its pollination system by aborting the seeds. This study showed that the rates of seed germination and allogamy of the seedlings depend on a complex combination of factors that vary in space and time. Male sterility of flowers, length of the flowering season and flowering synchrony of individuals within populations all favour high rates of cross-pollination, therefore increasing germination and allogamy rates. Flowering traits appear to be highly plastic and respond to local and seasonal conditions.

[Does Omega-3 supplementation after the age of 65 influence cognitive function? Results of a systematic review]. / ¿La ingesta o suplementación con ácidos grasos omega-3 a partir de los 65 años influye en la función cognitiva? Resultados de una revisión sistemática.

BACKGROUND: The percentage of the older population is progressively increasing as are diseases associated with aging such as cognitive decline (CD) and dementia. Observational epidemiological studies suggest that diets rich in omega 3 polyunsaturated fatty acids (w3-PUFA) might reduce the risk of CD and dementia. The main objective was to assess whether there is sufficient scientific evidence about the relationship between w3-PUFA supplementation in patients aged 65 or older and cognitive performance. METHODS: We used the Pubmed data base to search for articles related to w3-PUFA and CD or dementia. Initially we identified 582 articles, after applying the eligibility criterion we included six studies in this systematic review. RESULTS: The studies included were heterogeneous regarding population, measurement of exposure and outcome. Therefore, it was not possible to conduct a quantitative analysis. Two studies found that w3-PUFA supplementation decreased the risk of Alzheimer and improved cognitive performance. Two studies found an improvement in only one of the domains of cognitive performance (visual analogical classification and verbal fluency) and another two did not find any evidence of protection. CONCLUSIONS: We found few studies to support or refute the evidence that w3-PUFA supplementation in patients aged 65 or older improves cognitive performance or prevents dementia.

Fires can benefit plants by disrupting antagonistic interactions.

Fire has a key role in the ecology and evolution of many ecosystems, yet its effects on plant-insect interactions are poorly understood. Because interacting species are likely to respond to fire differently, disruptions of the interactions are expected. We hypothesized that plants that regenerate after fire can benefit through the disruption of their antagonistic interactions. We expected stronger effects on interactions with specialist predators than with generalists. We studied two interactions between two Mediterranean plants (Ulex parviflorus, Asphodelus ramosus) and their specialist seed predators after large wildfires. In A. ramosus we also studied the generalist herbivores. We sampled the interactions in burned and adjacent unburned areas during 2 years by estimating seed predation, number of herbivores and fruit set. To assess the effect of the distance to unburned vegetation we sampled plots at two distance classes from the fire perimeter. Even 3 years after the fires, Ulex plants experienced lower seed damage by specialists in burned sites. The presence of herbivores on Asphodelus decreased in burned locations, and the variability in their presence was significantly related to fruit set. Generalist herbivores were unaffected. We show that plants can benefit from fire through the disruption of their antagonistic interactions with specialist seed predators for at least a few years. In environments with a long fire history, this effect might be one additional mechanism underlying the success of fire-adapted plants.

Field heritability of a plant adaptation to fire in heterogeneous landscapes.

The strong association observed between fire regimes and variation in plant adaptations to fire suggests a rapid response to fire as an agent of selection. It also suggests that fire-related traits are heritable, a precondition for evolutionary change. One example is serotiny, the accumulation of seeds in unopened fruits or cones until the next fire, an important strategy for plant population persistence in fire-prone ecosystems. Here, we evaluate the potential of this trait to respond to natural selection in its natural setting. For this, we use a SNP marker approach to estimate genetic variance and heritability of serotiny directly in the field for two Mediterranean pine species. Study populations were large and heterogeneous in climatic conditions and fire regime. We first estimated the realized relatedness among trees from genotypes, and then partitioned the phenotypic variance in serotiny using Bayesian animal models that incorporated environmental predictors. As expected, field heritability was smaller (around 0.10 for both species) than previous estimates under common garden conditions (0.20). An estimate on a subset of stands with more homogeneous environmental conditions was not different from that in the complete set of stands, suggesting that our models correctly captured the environmental variation at the spatial scale of the study. Our results highlight the importance of measuring quantitative genetic parameters in natural populations, where environmental heterogeneity is a critical aspect. The heritability of serotiny, although not high, combined with high phenotypic variance within populations, confirms the potential of this fire-related trait for evolutionary change in the wild.

Unconscious context-specific proportion congruency effect in a stroop-like task.

Cognitive control is a central topic of interest in psychology and cognitive neuroscience and has traditionally been associated with consciousness. However, recent research suggests that cognitive control may be unconscious in character. The main purpose of our study was to further explore this area of research focusing on the possibly unconscious nature of the conflict adaptation effect, specifically the context-specific proportion congruency effect (CSPCE), by using a masked Stroop-like task where the proportion of congruency was associated to various masks. We used electrophysiological measures to analyze the neural correlates of the CSPCE. Results showed evidence of an unconscious CSPCE in reaction times (RTs) and the N2 and P3 components. In addition, the P2 component evoked by both target and masks indicated that the proportion of congruency was processed earlier than the congruency between the color word and the ink color of the target. Taken together, our results provided evidence pointing to an unconscious CSPCE.

Development of neural mechanisms of conflict and error processing during childhood: implications for self-regulation.

Regulation of thoughts and behavior requires attention, particularly when there is conflict between alternative responses or when errors are to be prevented or corrected. Conflict monitoring and error processing are functions of the executive attention network, a neurocognitive system that greatly matures during childhood. In this study, we examined the development of brain mechanisms underlying conflict and error processing with event-related potentials (ERPs), and explored the relationship between brain function and individual differences in the ability to self-regulate behavior. Three groups of children aged 4-6, 7-9, and 10-13 years, and a group of adults performed a child-friendly version of the flanker task while ERPs were registered. Marked developmental changes were observed in both conflict processing and brain reactions to errors. After controlling by age, higher self-regulation skills are associated with smaller amplitude of the conflict effect but greater amplitude of the error-related negativity. Additionally, we found that electrophysiological measures of conflict and error monitoring predict individual differences in impulsivity and the capacity to delay gratification. These findings inform of brain mechanisms underlying the development of cognitive control and self-regulation.

Genetic component of flammability variation in a Mediterranean shrub.

Recurrent fires impose a strong selection pressure in many ecosystems worldwide. In such ecosystems, plant flammability is of paramount importance because it enhances population persistence, particularly in non-resprouting species. Indeed, there is evidence of phenotypic divergence of flammability under different fire regimes. Our general hypothesis is that flammability-enhancing traits are adaptive; here, we test whether they have a genetic component. To test this hypothesis, we used the postfire obligate seeder Ulex parviflorus from sites historically exposed to different fire recurrence. We associated molecular variation in potentially adaptive loci detected with a genomic scan (using AFLP markers) with individual phenotypic variability in flammability across fire regimes. We found that at least 42% of the phenotypic variation in flammability was explained by the genetic divergence in a subset of AFLP loci. In spite of generalized gene flow, the genetic variability was structured by differences in fire recurrence. Our results provide the first field evidence supporting that traits enhancing plant flammability have a genetic component and thus can be responding to natural selection driven by fire. These results highlight the importance of flammability as an adaptive trait in fire-prone ecosystems.

'Anti-bee' and 'pro-bird' changes during the evolution of hummingbird pollination in Penstemon flowers.

Floral phenotypes may be as much the result of selection for avoidance of some animal visitors as selection for improving the interaction with better pollinators. When specializing on hummingbird-pollination, Penstemon flowers may have evolved to improve the morphological fit between bird and flower, or to exclude less-efficient bees, or both. We hypothesized how such selection might work on four floral characters that affect the mechanics of pollen transfer: anther/stigma exsertion, presence of a lower corolla lip, width of the corolla tube, and angle of flower inclination. We surgically modified bee-pollinated P. strictus flowers changing one trait at a time to make them resemble hummingbird-pollinated P. barbatus flowers, and measured pollen transfer by bumblebees and hummingbirds. Results suggest that, apart from 'pro-bird' adaptations, specific 'anti-bee' adaptations have been important in shaping hummingbird-flowers. Moreover, some trait changes may have been selected for only if changing in concert with other traits.

Feeding rates and daily path range of the Colombian woolly monkeys as evidence for between- and within-group competition.

Data on fruit feeding rates and daily path length were compared for four groups of woolly monkeys in Tinigua National Park, Colombia. Indirect evidence was found for feeding competition both within and between groups. Feeding rates were similar across groups of different sizes, but daily path lengths were longer in small and large groups when compared to medium-sized groups. The results suggest that the optimal group size in this study site is close to 20 individuals. Although the sample size was small and it was difficult to assess the influence of home range quality in some of the comparisons, this is one of the few studies providing empirical evidence supporting the importance of intergroup competition affecting group size in primates.

Expression of the leukocyte early activation antigen CD69 is regulated by the transcription factor AP-1.

The leukocyte Ag CD69, one of the earliest cell surface activation Ags, is up-regulated at the transcriptional level by proinflammatory stimuli involving the NF-kappaB/Rel family of transcription factors. However, promoter fragments lacking a critical kappaB motif respond to other stimuli such as phorbol esters and triggering Abs against TCR/CD3. Since the 5' promoter flanking region of the CD69 gene contains several putative binding sequences for transcription factor activating protein-1 (AP-1), we explored its role in the inducible expression of CD69. Stimuli that induce AP-1, but not NF-kappaB, such as pyrrolidine dithiocarbamate, augmented the cell surface expression of CD69 as well as its mRNA levels, and the promoter activity of the CD69 gene. This up-regulation is accompanied by an increased binding of jun and fos family members to a consensus AP-1 binding site of the proximal (-16) CD69 promoter region, which seems to be functionally responsive to different activation signals and is trans activated by c-jun expression vectors. Furthermore, cotransfection of a dominant negative version of c-jun, but not IkappaB, abolished the inducible transcriptional activity of the CD69 promoter. In conclusion, the inducible expression of the CD69 gene by mitogenic signals is regulated by the transcription factor AP-1.

Pyrrolidine dithiocarbamate inhibits the production of interleukin-6, interleukin-8, and granulocyte-macrophage colony-stimulating factor by human endothelial cells in response to inflammatory mediators: modulation of NF-kappa B and AP-1 transcription factors activity.

Endothelial cells (EC) play a key role in the inflammatory response, both by the production of proinflammatory cytokines and by their interaction with leukocytes. Molecular genetic analysis has demonstrated that functional NF-kappa B sites are involved in the transcription of interleukin-6 (IL-6), IL-8, and granulocyte-macrophage colony-stimulating factor (GM-CSF) genes in response to inflammatory mediators. Thus, we have explored the effect of two inhibitors of the NF-kappa B activation, pyrrolidine dithiocarbamate (PDTC) and N-acetylcysteine (NAC), on the production of these cytokines by EC. Both PDTC and NAC inhibited, in a dose-dependent manner, the synthesis of IL-6, IL-8, and GM-CSF induced by tumor necrosis factor (TNF)-alpha or bacterial lipopolysaccharides (LPS) in human umbilical vein endothelial cells (HUVEC). PDTC appeared to prevent IL-6, IL-8, and GM-CSF gene transcription, as it blocked the induction of specific mRNA by TNF-alpha or LPS. The TNF-alpha mediated transcriptional activation of a chloramphenicol acetyltransferase (CAT) plasmid containing three copies of the -72 kappa B binding site from the IL-6 promoter was abrogated by PDTC. According to transfection experiments, electrophoretic mobility shift assays (EMSA) demonstrated that the antioxidant prevented the induction of NF-kappa B DNA-binding activity by TNF-alpha. Under the same conditions, PDTC by itself or in combination with TNF-alpha, enhanced the DNA-binding activity of AP-1, as well as c-fos and c-jun mRNA levels. Altogether, these results indicate that the antioxidant PDTC specifically inhibits the transcription of IL-6, IL-8, and GM-CSF genes through the inhibition of the NF-kappa B activation, while increasing the expression of AP-1. Our data make evident the antiinflammatory and immunoregulatory potential of the pharmacological inhibition of the NF-kappa B activation. In addition, PDTC and related molecules may be a useful tool to explore the expression of genes involved in the inflammatory response.

Transcriptional up-regulation of intracellular adhesion molecule-1 in human endothelial cells by the antioxidant pyrrolidine dithiocarbamate involves the activation of activating protein-1.

The redox status of the cell plays an essential role in regulating signal transduction, transcription factor activity, and expression of cell surface molecules. In this study, we show that pyrrolidine dithiocarbamate (PDTC), a potent antioxidant agent, upregulated the cell surface expression of intercellular adhesion molecule-1 (ICAM-1) in human endothelial cells (EC). Further analysis of PDTC-mediated ICAM-1 up-regulation revealed that PDTC increased ICAM-1 mRNA levels and augmented its gene promoter activity. Transfection experiments in EC with reporter constructs harboring nested deletion fragments of the ICAM-1 promoter indicated the presence of a functional PDTC-responsive region located between positions -136 to -353 of the promoter. Gel retardation assays together with supershift analysis revealed that PDTC induced the binding of c-fos and c-jun to a consensus activating protein-1 (AP-1) binding site located at position -284. PDTC alone or in combination with TNF-alpha enhanced AP-1-dependent transactivation in HUVEC, as determined by DNA binding assays. The functional implication of AP-1 in the transcription of the ICAM-1 gene was further demonstrated by cotransfection experiments in which a c-jun expression vector induced the promoter activity of the PDTC-responsive element of the ICAM-1 promoter. Taken together, these results indicate that the antioxidant PDTC induces transcriptional activation of ICAM-1 and that this induction is mediated at least in part by the transcription factor AP-1. This mechanism might be operative in pathologic conditions in which a redox imbalance plays a key role, such as ischemia/reperfusion injury or arteriosclerosis.

Molecular and functional characterization of a mutant allele of the mitogen-activated protein-kinase gene SLT2(MPK1) rescued from yeast autolytic mutants.

We have further characterized the functionality of the Saccharomyces cerevisiae gene SLT2(MPK1), coding for a MAP-kinase homolog essential for cell integrity, which is involved in the Pkc1p signalling pathway. This gene was isolated on the basis of its capacity to complement the thermosensitive-autolytic, osmotic-remediable phenotype of lyt2 mutants. Both slt2delta and lyt2 mutants displayed a caffeine-sensitive phenotype consisting of cell lysis that was not dependent on temperature. Caffeine concentrations affecting the growth of these mutant strains were dependent on the genetic background, the SSD1 allele being very significant in this regard. The SLT2 allele of several lyt2 strains was both rescued and amplified by PCR. The recovered allele was shown to be non-functional as it could not complement the lytic phenotype of both deletion (slt2delta) and lyt2 strains. After nucleotide sequencing of the recovered allele, we found that the defect of lyt2 mutants consists in a substitution of an aspartic acid for a glycine at position 35 of the amino-acid sequence of Slt2p. Gly35 is the third glycine of a glycine cluster (Gly-X-Gly-X-X-Gly), a conserved region in protein kinases and other nucleotide-binding proteins. Keywords Yeast middle dot SLT2 middle dot MAP-kinase middle dot Caffeine