Pollen grain development is compromised in Arabidopsis agp6 agp11 null mutants

Arabinogalactan proteins (AGPs) are structurally complex plasma membrane and cell wall proteoglycans that are implicated in diverse developmental processes, including plant sexual reproduction. Male gametogenesis (pollen grain development) is fundamental to plant sexual reproduction. The role of two abundant, pollen-specific AGPs, AGP6, and AGP11, have been investigated here. The pollen specificity of these proteoglycans suggested that they are integral to pollen biogenesis and their strong sequence homology indicated a potential for overlapping function. Indeed, single gene transposon insertion knockouts for both AGPs showed no discernible phenotype. However, in plants homozygous for one of the insertions and heterozygous for the other, in homozygous double mutants, and in RNAi and amiRNA transgenic plants that were down-regulated for both genes, many pollen grains failed to develop normally, leading to their collapse. The microscopic observations of these aborted pollen grains showed a condensed cytoplasm, membrane blebbing and the presence of small lytic vacuoles. Later in development, the generative cells that arise from mitotic divisions were not seen to go into the second mitosis. Anther wall development, the establishment of the endothecium thickenings, the opening of the stomium, and the deposition of the pollen coat were all normal in the knockout and knockdown lines. Our data provide strong evidence that these two proteoglycans have overlapping and important functions in gametophytic pollen grain development

Caveolin-1 protects B6129 mice against Helicobacter pylori gastritis.

Caveolin-1 (Cav1) is a scaffold protein and pathogen receptor in the mucosa of the gastrointestinal tract. Chronic infection of gastric epithelial cells by Helicobacter pylori (H. pylori) is a major risk factor for human gastric cancer (GC) where Cav1 is frequently down-regulated. However, the function of Cav1 in H. pylori infection and pathogenesis of GC remained unknown. We show here that Cav1-deficient mice, infected for 11 months with the CagA-delivery deficient H. pylori strain SS1, developed more severe gastritis and tissue damage, including loss of parietal cells and foveolar hyperplasia, and displayed lower colonisation of the gastric mucosa than wild-type B6129 littermates. Cav1-null mice showed enhanced infiltration of macrophages and B-cells and secretion of chemokines (RANTES) but had reduced levels of CD25+ regulatory T-cells. Cav1-deficient human GC cells (AGS), infected with the CagA-delivery proficient H. pylori strain G27, were more sensitive to CagA-related cytoskeletal stress morphologies ("humming bird") compared to AGS cells stably transfected with Cav1 (AGS/Cav1). Infection of AGS/Cav1 cells triggered the recruitment of p120 RhoGTPase-activating protein/deleted in liver cancer-1 (p120RhoGAP/DLC1) to Cav1 and counteracted CagA-induced cytoskeletal rearrangements. In human GC cell lines (MKN45, N87) and mouse stomach tissue, H. pylori down-regulated endogenous expression of Cav1 independently of CagA. Mechanistically, H. pylori activated sterol-responsive element-binding protein-1 (SREBP1) to repress transcription of the human Cav1 gene from sterol-responsive elements (SREs) in the proximal Cav1 promoter. These data suggested a protective role of Cav1 against H. pylori-induced inflammation and tissue damage. We propose that H. pylori exploits down-regulation of Cav1 to subvert the host's immune response and to promote signalling of its virulence factors in host cells

Semi-analytic modeling of the EBL and consequences for extragalactic gamma-ray spectra

Attenuation of high-energy gamma rays by pair-production with UV, optical and IR extragalactic background light (EBL) photons provides a link between the history of galaxy formation and high-energy astrophysics. We present results from our latest semi-analytic models (SAMs), which employ the main ingredients thought to be important to galaxy formation and evolution, as well as an improved model for reprocessing of starlight by dust to mid- and far-IR wavelengths. These SAMs are based upon a Lambda-CDM hierarchical structural formation scenario, and are successful in reproducing a large variety of observational constraints such as number counts, luminosity and mass functions, and color bimodality. Our fiducial model is based upon a WMAP5 cosmology, and treats dust emission using empirical templates. This model predicts a background flux considerably lower than optical and near-IR measurements that rely on subtraction of zodiacal and galactic foregrounds, and near the lower bounds set by number counts of resolvable sources at a large number of wavelengths. We also show the results of varying cosmological parameters and dust attenuation model used in our SAM. For each EBL prediction, we show how the optical depth due to electron-positron pair-production is affected by redshift and gamma-ray energy, and the effect of gamma-ray absorption on the spectra of a variety of extragalactic sources. We conclude with a discussion of the implications of our work, comparisons to other models and key measurements of the EBL and a discussion of how the burgeoning science of gamma-ray astronomy will continue to help constrain cosmology. The low EBL flux predicted by our fiducial model suggests an optimistic future for further studies of distant gamma-ray sources.Comment: 23 pages, 11 figures, 3 tables, accepted by MNRAS; this preprint matches accepted versio

Differential Patterns of Food Appreciation during Consumption of a Simple Food in Congenitally Anosmic Individuals: An Explorative Study

Food is evaluated for various attributes. One of the key food evaluation domains is hedonicity. As food is consumed, its hedonic valence decreases (due to prolonged sensory stimulation) and hedonic habituation results. The aim of the present study was to investigate changes in food pleasantness ratings during consumption of a simple food by individuals without olfactory experience with food as compared to normosmics. 15 congenital anosmics and 15 normosmic controls were each presented with ten 10 g banana slices. Each was visually inspected, then smelled and chewed for ten seconds and subsequently rated for hedonicity on a 21-point scale. There was a significant difference in pleasantness ratings between congenital anosmics and controls (F(1, 26) = 6.71, p = .02) with the anosmics exhibiting higher ratings than the controls, a significant main repeated-measures effect on the ratings (F(1.85, 48) = 12.15, p<.001), which showed a decreasing trend over the course of consumption, as well as a significant portion*group interaction (F(1.85, 48) = 3.54, p = .04), with the anosmic participants experiencing a less pronounced decline. The results of the present explorative study suggest that over the course of consumption of a simple food, congenitally anosmic individuals experience differential patterns of appreciation of food as compared to normosmics. In this particular case, the decrease of hedonic valence was less pronounced in congenital anosmics

Detection of Extended Red Emisson in the Diffuse Interstellar Medium

Extended Red Emission (ERE) has been detected in many dusty astrophysical objects and this raises the question: Is ERE present only in discrete objects or is it an observational feature of all dust, i.e. present in the diffuse interstellar medium? In order to answer this question, we determined the blue and red intensities of the radiation from the diffuse interstellar medium (ISM) and examined the red intensity for the presence of an excess above that expected for scattered light. The diffuse ISM blue and red intensities were obtained by subtracting the integrated star and galaxy intensities from the blue and red measurements made by the Imaging Photopolarimeter (IPP) aboard the Pioneer 10 and 11 spacecraft. The color of the diffuse ISM was found to be redder than the Pioneer intensities, contrary to that expected for scattered light (Diffuse Galactic Light [DGL]). The red DGL was calculated using the blue diffuse ISM intensities and the approximately invariant color of the DGL calculated with the DGL model. Subtracting the calculated red DGL from the red diffuse ISM intensities resulted in the detection of an excess red intensity. This represents the likely detection of ERE in the diffuse ISM since H-alpha emission cannot account for the strength of this excess and the only other known emission process applicable to the diffuse ISM is ERE. Thus, ERE appears to be a general characteristic of dust. From the correlation between N_HI and ERE intensity the ERE photon conversion efficiency was estimated at 10 +/- 3%.Comment: 44 pages (41 figures included), to be published in the ApJ, new version corrected for small error in fig. 2

An atmospheric radiation model for Cerro Paranal. I. The optical spectral range

The Earth's atmosphere affects ground-based astronomical observations. Scattering, absorption, and radiation processes deteriorate the signal-to-noise ratio of the data received. For scheduling astronomical observations it is, therefore, important to accurately estimate the wavelength-dependent effect of the Earth's atmosphere on the observed flux. In order to increase the accuracy of the exposure time calculator of the European Southern Observatory's (ESO) Very Large Telescope (VLT) at Cerro Paranal, an atmospheric model was developed as part of the Austrian ESO In-Kind contribution. It includes all relevant components, such as scattered moonlight, scattered starlight, zodiacal light, atmospheric thermal radiation and absorption, and non-thermal airglow emission. This paper focuses on atmospheric scattering processes that mostly affect the blue (< 0.55 mum) wavelength regime, and airglow emission lines and continuum that dominate the red (> 0.55 mum) wavelength regime. While the former is mainly investigated by means of radiative transfer models, the intensity and variability of the latter is studied with a sample of 1186 VLT FORS1 spectra. For a set of parameters such as the object altitude angle, Moon-object angular distance, ecliptic latitude, bimonthly period, and solar radio flux, our model predicts atmospheric radiation and transmission at a requested resolution. A comparison of our model with the FORS1 spectra and photometric data for the night-sky brightness from the literature, suggest a model accuracy of about 20%. This is a significant improvement with respect to existing predictive atmospheric models for astronomical exposure time calculators.Comment: 23 pages, 21 figures, accepted for publication in A&

Subliminally Perceived Odours Modulate Female Intrasexual Competition: An Eye Movement Study

Background: Evidence suggests that subliminal odorants influence human perception and behavior. It has been hypothesized that the human sex-steroid derived compound 4,16-androstadien-3-one (androstadienone) functions as a human chemosignal. The most intensively studied steroid compound, androstadienone is known to be biologically relevant since it seems to convey information about male mate quality to women. It is unclear if the effects of androstadienone are menstrual cycle related. Methodology/Principal Findings: In the first experiment, heterosexual women were exposed to androstadienone or a control compound and asked to view stimuli such as female faces, male faces and familiar objects while their eye movements were recorded. In the second experiment the same women were asked to rate the level of stimuli attractiveness following exposure to the study or control compound. The results indicated that women at high conception risk spent more time viewing the female than the male faces regardless of the compound administered. Women at a low conception risk exhibited a preference for female faces only following exposure to androstadienone. Conclusions/Significance: We contend that a woman’s level of fertility influences her evaluation of potential competitors (e.g., faces of other women) during times critical for reproduction. Subliminally perceived odorants, such as androstadienone, might similarly enhance intrasexual competition strategies in women during fertility phases not critica

The Roles and Interactions of Symbiont, Host and Environment in Defining Coral Fitness

Background: Reef-building corals live in symbiosis with a diverse range of dinoflagellate algae (genus Symbiodinium) that differentially influence the fitness of the coral holobiont. The comparative role of symbiont type in holobiont fitness in relation to host genotype or the environment, however, is largely unknown. We addressed this knowledge gap by manipulating host-symbiont combinations and comparing growth, survival and thermal tolerance among the resultant holobionts in different environments.\ud Methodology/Principal Findings: Offspring of the coral, Acropora millepora, from two thermally contrasting locations, were experimentally infected with one of six Symbiodinium types, which spanned three phylogenetic clades (A, C and D), and then outplanted to the two parental field locations (central and southern inshore Great Barrier Reef, Australia). Growth and survival of juvenile corals were monitored for 31–35 weeks, after which their thermo-tolerance was experimentally assessed. Our results showed that: (1) Symbiodinium type was the most important predictor of holobiont fitness, as measured by growth, survival, and thermo-tolerance; (2) growth and survival, but not heat-tolerance, were also affected by local environmental conditions; and (3) host population had little to no effect on holobiont fitness. Furthermore, coral-algal associations were established with symbiont types belonging to clades A, C and D, but three out of four symbiont types belonging to clade C failed to establish a symbiosis. Associations with clade A had the lowest fitness and were unstable in the field. Lastly, Symbiodinium types C1 and D were found to be relatively thermo-tolerant, with type D conferring the highest tolerance in A. millepora.\ud Conclusions/Significance: These results highlight the complex interactions that occur between the coral host, the algal symbiont, and the environment to shape the fitness of the coral holobiont. An improved understanding of the factors affecting coral holobiont fitness will assist in predicting the responses of corals to global climate change

Variation in Symbiodinium ITS2 Sequence Assemblages among Coral Colonies

Endosymbiotic dinoflagellates in the genus Symbiodinium are fundamentally important to the biology of scleractinian corals, as well as to a variety of other marine organisms. The genus Symbiodinium is genetically and functionally diverse and the taxonomic nature of the union between Symbiodinium and corals is implicated as a key trait determining the environmental tolerance of the symbiosis. Surprisingly, the question of how Symbiodinium diversity partitions within a species across spatial scales of meters to kilometers has received little attention, but is important to understanding the intrinsic biological scope of a given coral population and adaptations to the local environment. Here we address this gap by describing the Symbiodinium ITS2 sequence assemblages recovered from colonies of the reef building coral Montipora capitata sampled across Kāne'ohe Bay, Hawai'i. A total of 52 corals were sampled in a nested design of Coral Colony(Site(Region)) reflecting spatial scales of meters to kilometers. A diversity of Symbiodinium ITS2 sequences was recovered with the majority of variance partitioning at the level of the Coral Colony. To confirm this result, the Symbiodinium ITS2 sequence diversity in six M. capitata colonies were analyzed in much greater depth with 35 to 55 clones per colony. The ITS2 sequences and quantitative composition recovered from these colonies varied significantly, indicating that each coral hosted a different assemblage of Symbiodinium. The diversity of Symbiodinium ITS2 sequence assemblages retrieved from individual colonies of M. capitata here highlights the problems inherent in interpreting multi-copy and intra-genomically variable molecular markers, and serves as a context for discussing the utility and biological relevance of assigning species names based on Symbiodinium ITS2 genotyping

Marine Biodiversity in the Caribbean: Regional Estimates and Distribution Patterns

This paper provides an analysis of the distribution patterns of marine biodiversity and summarizes the major activities of the Census of Marine Life program in the Caribbean region. The coastal Caribbean region is a large marine ecosystem (LME) characterized by coral reefs, mangroves, and seagrasses, but including other environments, such as sandy beaches and rocky shores. These tropical ecosystems incorporate a high diversity of associated flora and fauna, and the nations that border the Caribbean collectively encompass a major global marine biodiversity hot spot. We analyze the state of knowledge of marine biodiversity based on the geographic distribution of georeferenced species records and regional taxonomic lists. A total of 12,046 marine species are reported in this paper for the Caribbean region. These include representatives from 31 animal phyla, two plant phyla, one group of Chromista, and three groups of Protoctista. Sampling effort has been greatest in shallow, nearshore waters, where there is relatively good coverage of species records; offshore and deep environments have been less studied. Additionally, we found that the currently accepted classification of marine ecoregions of the Caribbean did not apply for the benthic distributions of five relatively well known taxonomic groups. Coastal species richness tends to concentrate along the Antillean arc (Cuba to the southernmost Antilles) and the northern coast of South America (Venezuela – Colombia), while no pattern can be observed in the deep sea with the available data. Several factors make it impossible to determine the extent to which these distribution patterns accurately reflect the true situation for marine biodiversity in general: (1) highly localized concentrations of collecting effort and a lack of collecting in many areas and ecosystems, (2) high variability among collecting methods, (3) limited taxonomic expertise for many groups, and (4) differing levels of activity in the study of different taxa