Significant Variation In Abundance Research Articles

Landscape patterns influence communities of medium- to large-bodied vertebrates in undisturbed terra firme forests of French Guiana

Abstract:Whereas broad-scale Amazonian forest types have been shown to influence the structure of the communities of medium- to large-bodied vertebrates, their natural heterogeneity at smaller scale or within the terra firme forests remains poorly described and understood. Diversity indices of such communities and the relative abundance of the 21 most commonly observed species were compared from standardized line-transect data across 25 study sites distributed in undisturbed forests in French Guiana. We first assessed the relevance of a forest typology based on geomorphological landscapes to explain the observed heterogeneity. As previously found for tree beta-diversity patterns, this new typology proved to be a non-negligible factor underlying the beta diversity of the communities of medium- to large bodied vertebrates in French Guianan terra firme forests. Although the species studied are almost ubiquitous across the region, they exhibited habitat preferences through significant variation in abundance and in their association index with the different landscape types. As terra firme forests represent more than 90% of the Amazon basin, characterizing their heterogeneity – including faunal communities – is a major challenge in neotropical forest ecology.

Comparison of Rock Varnish Bacterial Communities with Surrounding Non-Varnished Rock Surfaces: Taxon-Specific Analysis and Morphological Description.

Rock varnish is a thin layer of Fe and Mn oxyhydroxides with embedded clay minerals that contain an increased Mn/Fe ratio compared to that of the Earth's crust. Even if the study of rock varnish has important implications in several fields, the composition of epilithic bacterial communities and the distribution of taxa on varnish surfaces are still not wholly described. The aim of this study was (i) to identify the bacterial taxa which show the greatest variation between varnish and non-varnish environments, collected from the same rock, and (ii) to describe the morphology of epilithic communities through scanning electron microscopy (SEM). Triplicate samples of rock surfaces with varnish and triplicate samples without varnish were collected from five sites in Matsch Valley (South Tyrol, Italy). The V4 region of 16S rRNA gene was analyzed by Illumina sequencing. Fifty-five ubiquitous taxa have been examined to assess variation between varnish and non-varnish. Cyanobacteria, Chloroflexi, Proteobacteria along with minor taxa such as Solirubrobacterales, Conexibaxter, and Rhodopila showed significant variations of abundance, diversity, or both responding to the ecology (presence/absence of varnish). Other taxa, such as the genus Edaphobacter, showed a more marked spatial variation responding to the sampling site. SEM images showed a multitude of bacterial morphologies and structures involved in the process of attachment and creation of a suitable environment for growth. The features emerging from this analysis suggest that the highly oxidative Fe and Mn-rich varnish environment favors anoxigenic autotrophy and establishment of highly specialized bacteria.

Proteome changes during yeast-like and pseudohyphal growth in the biofilm-forming yeast Pichia fermentans.

The Pichia fermentans strain DISAABA 726 is a biofilm-forming yeast that has been proposed as biocontrol agent to control brown rot on apple. How ever, when inoculated on peach, strain 726 shows yeast-like to pseudohyphal transition coupled to a pathogenic behaviour. To identify the proteins potentially involved in such transition process, a comparative proteome analysis of P. fermentans 726 developed on peach (filamentous growth) vs apple (yeast-like growth) was carried out using two-dimensional gel electrophoresis coupled with mass spectrometry analysis. The proteome comparison was also performed between the two different cell morphologies induced in a liquid medium amended with urea (yeast-like cells) or methionine (filamentous cells) to exclude fruit tissue impact on the transition. Seventy-three protein spots showed significant variations in abundance (±twofold, p < 0.01, confidence intervals 99 %) between pseudohyphal vs yeast-like morphology produced on fruits. Among them, 30 proteins changed their levels when the two morphologies were developed in liquid medium. The identified proteins belong to several pathways and functions, such as glycolysis, amino acid synthesis, chaperones, and signalling transduction. The possible role of a group of proteins belonging to the carbohydrate pathway in the metabolic re-organisation during P. fermentans dimorphic transition is discussed.

Pit B or not Pit B? The pitfall array is the question

Pitfall trapping is a long established method for trapping terrestrial vertebrates globally. Many variations in bucket and drift fence arrays are used. Recent survey guidelines have been published for Queensland and the Northern Territory. In Queensland a “T” pattern is recommended, and we used data collected over five years to assess whether the use of this array, with the addition of a central bucket (Pit B), results in more captures, particularly in the central bucket. A total of 263 sites representing 1052 bucket samples were examined and the differences in capture abundance in bucket location was tested using analysis of variance. Pitfall bucket location significantly affected the captures of Dasyuridae, Muridae, Agamidae, Pygopodidae, Scincidae (P<0.1), and mean abundance was highest in the central Pit B except for Agamidae. There was also significant variation in abundance across habitat type for these families, excluding Dasyuridae, but including Gekkonidae. We conclude that having a central bucket where drift fences join can increase trap success, and this is a function of effective trapping area (i.e. catchment of animal activity and length of drift fence per bucket). Increased captures may have some relationship to habitat type (i.e. small mammals more abundant in grassland habitat). Though this particular array has some benefits in increasing trap success, the use of multiple survey techniques is recommended for any thorough fauna inventory.

Effect of Salinity and Calcium on Tomato Fruit Proteome

Salinity is a major abiotic stress that adversely affects plant growth and productivity. The physiology of the tomato in salty and nonsalty conditions has been extensively studied, providing an invaluable base to understand the responses of the plants to cultural practices. However few data are yet available at the proteomic level looking for the physiological basis of fruit development, under salt stress. Here, we report the effects of salinity and calcium on fruit proteome variations of two tomato genotypes (Cervil and Levovil). Tomato plants were irrigated with a control solution (3 dSm(-1)) or with saline solutions (Na or Ca+Na at 7.6 dSm(-1)). Tomato fruits were harvested at two ripening stages: green (14 days post-anthesis) and red ripe. Total proteins were extracted from pericarp tissue and separated by two-dimensional gel electrophoresis. Among the 600 protein spots reproducibly detected, 53 spots exhibited significant abundance variations between samples and were submitted to mass spectrometry for identification. Most of the identified proteins were involved in carbon and energy metabolism, salt stress, oxidative stress, and proteins associated with ripening process. Overall, there was a large variation on proteins abundance between the two genotypes that can be correlated to salt treatment or/and fruit ripening stage. The results showed a protective effect of calcium that limited the impact of salinization on metabolism, ripening process, and induced plant salt tolerance. Collectively, this work has improved our knowledge about salt and calcium effect on tomato fruit proteome.

Impoundment effects in the population of &lt;i&gt;Auchenipterus osteomystax&lt;/i&gt; (Siluriformes: Auchenipteridae): a Neotropical reservoir case

New impoundments provide opportunities to check whether species that present enough feeding flexibility in natural conditions may take advantage of this situation and, without reproductive restriction, can occupy the most conspicuous habitat in a large reservoir (open areas) and present higher success in the colonization of the new environment. We examined variations in the abundance and feeding of A. osteomystax in two environments, one natural (Sinhá Mariana floodplain lake) and one dammed (Manso Reservoir), during two periods: the first year after the filling phase and three years later. Our goal was to evaluate the occupation of the new habitat (Manso Reservoir), by this species, as well as to test the hypothesis that in the reservoir, unlike the natural environment, there are remarkable changes in diet between the periods. Fish were sampled monthly in the floodplain lake and in the reservoir during two annual periods using gillnets. To evaluate the differences in abundance of A. osteomystax we employed the Kruskal -Wallis test, and the diet analysis was carried out using frequency of occurrence and volumetric methods. Temporal differences in the diet were tested by Kruskal-Wallis test using the scores from a detrended correspondence analysis. A. osteomystax was significantly more abundant in the floodplain lake, where the captures were higher than in the reservoir in almost all months analyzed, and significant variations in abundance between the two periods were not recorded in either the reservoir or the floodplain lake. The diet variation between the two periods, which had a time lag of three years between them, was much less pronounced in the natural environment, where the resource availability is essentially regulated by seasonality. Thus, our hypothesis was accepted; that is, the interannual variations in the diet ofA. osteomystax are more relevant in an artificial environment than in a natural one.

Yale Lyme Disease Risk Maps Are Not Accurate for the South in 2012

Dear Sir: The paper, “Human Risk of Infection with Borrelia burgdorferi, the Lyme Disease Agent, in Eastern United States”1 designates most of Virginia and the entire south below and west of Virginia as a low risk area for Lyme disease. The authors state, “The absence of infected host-seeking nymphs in most southern states suggests reported cases may be mostly misdiagnosis or travel.” Because their 6- to 8-year-old data are in contrast to recent data from Virginia, West Virginia, North Carolina, and Florida,2–5 I am concerned that harm to southern patients and public health efforts could occur if medical professionals used this work to aid in diagnosis and consideration of risk as the authors suggest they do. Although bites from Ixodes scapularis ticks and Lyme disease are not as common as in the northeast, they do occur. North Carolina declared a central county (Wake) endemic for Lyme disease in 20106 and a growing number of other counties have had one local case meeting state and Centers for Disease Control and Prevention (CDC) standards. As of 2011, Virginia had declared about two-thirds of their counties endemic for Lyme disease including at least seven in the far west and five along the Virginia-North Carolina border.2 By the authors' own description their methods for collecting I. scapularis ticks including seasonality and drags were not suitable for the south, although acknowledging that these ticks are widespread in the region. Thus, following their sampling criteria based on northern methods, they collected only 1 tick each in Alabama and Georgia (in 2004), five in North Carolina (in 2005 and 2006), and 2 in South Carolina (2004 and 2005). Other states in the deep south were not sampled for this paper (see supplemental materials online)1,7,8; these few numbers cannot be expected to produce reliable results for the density of infected ticks. The sparse number of ticks collected was attributed to different host-seeking behavior from northern climes. These different behaviors are used to explain the lower likelihood of humans being bitten in the south. Although there is some merit to this argument, such assumptions may need further exploration now that there is evidence of emerging disease in the south and widespread I. scapularis tick populations.9 Tick populations are dynamic. Studies have found significant variation in abundance and activity patterns among years and habitats.10,11 Generalizing from short-term or spatially limited studies, as this study1 did for southern regions, is not recommended. As stated by Schulze and others, “Failure to recognize the biases in … sampling techniques can potentially lead to incorrect conclusions that can have significant public health consequences.”12 For example, in contrast to the Yale data, a 2006 study conducted by Smith and others in Chatham County, North Carolina collected 3,446 ticks of which 15 were nymphal I. scapularis. Forty percent of these were positive for B. burgdorferi sensu lato.3 The authors state their maps (which show zero risk of infected ticks and low risk for Lyme disease for all of the south below Virginia except an emerging coastal area in North Carolina) may be used to make personal protection decisions, to plan efficient allocation of public health resources, and to assist the medical community in considering diagnosis and treatment decisions. Global models and out-of-date data for Lyme disease demand cautious interpretation when it comes to public health recommendations and individual diagnosis and treatment decisions. Evidence-based medicine's need for up-to-date local data supersedes the use of the Yale Lyme disease risk maps.

Effect of small-scale woodland clearing and thinning on vertebrate fauna in a largely intact tropical savanna mosaic

Context Habitat degradation and fragmentation of vegetation can transform and deplete local wildlife populations, and is a key threatening process globally. In northern Australian tropical savannas, clearing is relatively rare across the biome, although it is slowly intensifying as a result of increasing agricultural development. However, the terrestrial vertebrates in these largely intact landscapes are undergoing current population declines because of a variety of land-management changes, one of which is increasing land clearing; therefore, there is a need to understand the relative effect of small-scale land clearing the fauna. Aims The present study examined the variation in abundance of birds, mammals and reptiles in intact, thinned and cleared Eucalyptus woodlands in a tropical savanna bioregion. Methods The vertebrate fauna were sampled in 88 sites over two general geographic locations within the Desert Uplands in 2005 and 2006. Standardised 1-ha surveys were employed in a single vegetation type and across three treatments. As two discrete locations were examined, linear mixed models were used in the analysis. Key results The fauna composition varied significantly across the intact, thinned and cleared sites. Bird species richness reduced from intact to thinned and cleared sites, and reptile richness and abundance declined in cleared sites, but was largely unaffected by thinning. Seventeen bird species recorded significant variation in abundance across the three vegetation structural types, with 12 most abundant in the intact sites. Mammals on the whole were recorded in very low abundances and in few sites. For reptiles, two were most abundant in thinned sites and three in intact sites. Conclusions In the present study, we have demonstrated that small-scale clearing and vegetation manipulation via thinning, even within largely intact tropical savanna woodland, can cause localised depletion of some species, although most notably where the vegetation disruption was most severe (i.e. clearing). Birds are most affected, and many species that declined in abundance are the same as those that suffered severe population reductions as a result of broad-scale clearing in south-eastern Australia. Implications The proposed increase in the intensity of agricultural land use in northern Australia will result in incremental landscape change as a result of clearing. Understanding how the gradual reduction of vegetation cover and habitat will change the faun assemblage is important for pre-emptive conservation planning. This is vital to avoid the mistakes of extensive landscape change in southern Australia that has left a legacy of a permanently depleted fauna.

Hurricane effects on subtropical pine rocklands of the Florida Keys

We investigate the effects of Hurricane Wilma’s storm surge (23–24 October 2005) on the dominant tree Pinus elliottii var densa (South Florida slash pine) and rare plant species in subtropical pine rocklands of the Lower Florida Keys. We examine the role of elevation on species abundance in 1995 (Hurricane Betsy in 1965), 2005 (Hurricane Georges in 1998), and 2008 (Hurricane Wilma in 2005) to investigate if hurricanes influence abundance by eliminating plants at lower elevation on Big Pine Key, the largest island in the Lower Florida Keys. We compare densities before and after Hurricane Wilma over the 2005–2008 sampling period and examine the role of elevation on changes in pine and rare species densities three years after Hurricane Wilma. We use elevation to assess the impact of hurricanes because elevation determined whether a location was influenced by storm surge (maximum surge of 2 m) in the Lower Florida Keys, where pine rocklands occur at a maximum elevation of 3 m. In 1995 (30 years after a major storm), elevation did not explain the abundance of South Florida slash pine or Chamaecrista lineata, but explained significant variation in abundance of Chamaesyce deltoidea. The latter two species are rare herbaceous plants restricted to pine rocklands. In 2008, 3 years after Hurricane Wilma, the positive relationship between elevation and abundance was strongest for South Florida slash pine, C. deltoidea, and C. lineata. Effects of Hurricane Wilma were not significant for rare species with wider distribution, occurring in plant communities adjacent to pine rocklands and in disturbed rocklands. Our results suggest that hurricanes drive population dynamics of South Florida slash pine and rare species that occur exclusively in pine rocklands at higher elevations. Rare species restricted to pine rocklands showed dramatic declines after Hurricane Wilma and were eliminated at elevations <0.5 m. Widely distributed rare species did not show significant changes in density after Hurricane Wilma. Abundance increased with elevation for South Florida slash pine and C. lineata after the hurricane. In an environment influenced by sea level rise, concrete plans to conserve pine ecosystems are warranted. Results from this study will help define conservation strategies by strengthening predictive understanding of plant responses to disturbance in the backdrop of sea level rise.

A quantitative comparison of frugivorous tephritids (Diptera: Tephritidae) in tropical forests and rural areas of the Democratic Republic of Congo

Most of the current knowledge about African tephritids originates from studies performed in agricultural areas, while information about their distribution in pristine or moderately disturbed environments is extremely scarce. This study aims at (i) describing levels of spatial variability of frugivorous tephritids in tropical forests and small rural villages of the Congo River basin and (ii) verifying if human-mediated activities, such as small-scale agriculture and trade, can affect their distribution patterns. Four locations were sampled along a 250 km stretch of the Congo River. At each location, pristine and disturbed habitats (i.e. tropical forests and small rural villages, respectively) were sampled, with three replicate sites in each combination of habitat and location. Sampling with modified McPhail traps baited with four different attractants yielded 819 tephritid specimens of 29 species from seven genera (Bactrocera, Carpophthoromyia, Ceratitis, Dacus, Celidodacus, Perilampsis, Trirhithrum). The three most abundant species sampled (Dacus bivittatus, D. punctatifrons, Bactrocera invadens) showed significant variations in abundance across locations and sites and accounted for 98.29% of the overall dissimilarity between habitats. Assemblages differed among locations and sites while they showed significant differences between pristine and disturbed habitats in two out of the four locations. This study shows that frugivorous tephritids in central Congo have remarkably patchy distributions with differences among locations and sites representing the main source of variability. Our data show that, in rural villages of central Democratic Republic of Congo, human activities, such as small-scale agriculture and local commerce, are not always sufficient to promote differences between the tephritid assemblages of villages and those of the surrounding tropical forests.

Salt and genotype impact on plant physiology and root proteome variations in tomato

To evaluate the genotypic variation of salt stress response in tomato, physiological analyses and a proteomic approach have been conducted in parallel on four contrasting tomato genotypes. After a 14 d period of salt stress in hydroponic conditions, the genotypes exhibited different responses in terms of plant growth, particularly root growth, foliar accumulation of Na(+), and foliar K/Na ratio. As a whole, Levovil appeared to be the most tolerant genotype while Cervil was the most sensitive one. Roma and Supermarmande exhibited intermediary behaviours. Among the 1300 protein spots reproducibly detected by two-dimensional electrophoresis, 90 exhibited significant abundance variations between samples and were submitted to mass spectrometry for identification. A common set of proteins (nine spots), up- or down-regulated by salt-stress whatever the genotype, was detected. But the impact of the tomato genotype on the proteome variations was much higher than the salt effect: 33 spots that were not variable with salt stress varied with the genotype. The remaining number of variable spots (48) exhibited combined effects of the genotype and the salt factors, putatively linked to the degrees of genotype tolerance. The carbon metabolism and energy-related proteins were mainly up-regulated by salt stress and exhibited most-tolerant versus most-sensitive abundance variations. Unexpectedly, some antioxidant and defence proteins were also down-regulated, while some proteins putatively involved in osmoprotectant synthesis and cell wall reinforcement were up-regulated by salt stress mainly in tolerant genotypes. The results showed the effect of 14 d stress on the tomato root proteome and underlined significant genotype differences, suggesting the importance of making use of genetic variability.

Quantitative Proteome and Acidic Subproteome Profiling of Candida albicans Yeast-to-Hypha Transition

Candida albicans yeast-to-hypha morphological transition is involved in the virulence strategy of this opportunistic fungal pathogen. Changes in relative abundance of the Candida proteome related to this process were analyzed using different two-dimensional differential in-gel electrophoresis (2D-DIGE)-based approaches. First, a comparative analysis of yeast and hyphal cytoplasmic proteins allowed the detection of 106 protein spots with significant variation in abundance. Sixty-one of them, corresponding to 46 proteins, were identified. As most of the differentially abundant proteins had an acidic isoelectric point, a large-scale prefractionation approach to analyze the acidic C. albicans subproteome was carried out. Ninety acidic C. albicans proteins were identified by either gel-based or nongel-based approaches. Additionally, different workflows combining preparative isoelectric focusing, Cy labeling, and narrow pH gradient 2-DE gels were tested to analyze the differences in relative protein abundance between yeast and hyphal acidic subproteomes. It was possible to identify 21 differentially abundant acidic proteins; 10 of them were not identified in the previous 2D-DIGE gels. Functional and network interaction analyses of the 56 differentially abundant proteins identified by both approaches rendered an integrated view of metabolic and cellular process reorganization during the yeast-to-hypha transition. With these results, we propose a model of metabolic reorganization.

Proteomic analysis of muscle tissue from gilthead sea bream ( Sparus aurata, L.) farmed in offshore floating cages

Characterization of the muscle tissue proteome is key to many aspects of fish aquaculture, encompassing physiology, growth, food safety, seafood authentication and quality, traceability and shelf-life. In this study, a 2D-PAGE-MS study was performed on gilthead sea bream ( Sparus aurata, L.) muscle tissue along the production cycle in four offshore floating cage plants and two repopulation lagoons located in different areas of Sardinia, Italy. The aim of this study was to accomplish systematic characterization of the gilthead sea bream muscle proteome, and to gather data about its variability in physiological conditions occurring in both farmed and wild fish. In general, a relatively stable protein expression pattern was observed in farmed sea bream muscle compared to other more dynamic tissue proteomes, such as liver. However, several statistically significant variations in abundance of some proteins and their isoforms were detected, related to growth and environmental factors. Among these, parvalbumins, troponins, and Wap65 showed variations according to fish length and water temperature. Interestingly, the ratio of structural proteins versus glycolytic enzymes was also observed to change during the production cycle, showing an increase with fish length. In order to assess whether the farming conditions were able to induce alterations in the muscle proteome, farmed and wild fish were subjected to a differential proteomics analysis. The data gathered in this study indicate that the protein expression profile of muscle tissue is comparable in wild and maricultured gilthead sea breams of commercial size, supporting the view that farming in offshore floating cages might favor proper muscle tissue development, and therefore enable the production of higher quality fish. In conclusion, this work describes the detailed characterization of the sea bream muscle proteome, and provides a number of insights on its size and environment-related variability.

Structure of benthic macroinvertebrates and dynamics in the northern lagoon of Tunis

Sampling data on abiotic parameters and benthic communities in the northern lagoon of Tunis were obtained seasonally from November 1999 to November 2000. Abiotic parameters studied revealed evident improvement of water quality compared with previous. Indeed, management has re-established a tidal marine influence (Gulf of Tunis), induced a remarkable change in physico-chemical parameters and as a consequence, a regulation of the lagoon environmental quality. A total of 90 species of benthic macroinvertebrates, belonging to seven different taxa were collected in the northern lagoon of Tunis. A comparison of ecological indices indicate significant variations in the spatial and seasonal distribution and structure of the benthic community and reflect changes that might be related to open marine water and climatic influences as well as effects of discharge of the neighbouring city. Generally, the lagoon macrobenthic community appeared to be better structured, richer and more diverse than the one described before sanitation works began. However, significant disturbance of the benthic communities is detected in the south-eastern lagoon zone (C) and is dominated by disturbance indicator species. In contrast, the Station A2 which is sufficiently influenced by marine currents, is dominated by species of marine affinity and indicates an undisturbed zone. Multivariate analysis indicates heterogeneity in the benthic community structure between stations and suggests that the most significant variations of abundance occur in the groups: Anthozoa, Placophora, Cephalopoda, Ascidia and Echinodermata. The results of correspondence analysis also testify to a gradational distribution of benthic species in relation to hydrological and edaphic (organic matter) factors.

Simplification of a coffee foliage-dwelling beetle community under low-shade management

Abstract Coffee agroforests may be structurally and floristically complex and may contain a significant fraction of species from biodiverse and threatened tropical montane forest biotas; hence, understanding the dynamics of tropical forest biodiversity in coffee agroecosystems has emerged as a centrally important area of tropical conservation biology research. We conducted a morphospecies analysis on foliage-dwelling beetles collected from coffee plants on four coffee farms in southern Chiapas, Mexico, to characterize variation in the abundance, species richness, and species composition of this mega-diverse taxon in relation to coffee cultivation system, spatio-temporal variation, and predator removal. We constructed thirty-two cages to exclude birds and bats on four farms, each enclosing 7–10 coffee plants and paired with an adjacent uncaged control plot, and then collected beetles from coffee foliage with D-Vac aspirators in each plot once every 3 months for one year. We classified the 2662 beetles collected into 293 morphospecies, representing 42 families of beetles. Extrapolation and interpolation analyses revealed a very high level of species richness, with no plateau and only a slight leveling trend observed in our species accumulation curves. We found that low-shade systems contain equal or higher beetle abundance, lower species richness, more highly homogenized species composition, and higher abundance of coffee berry borer pests on coffee foliage than do high-shade systems. We observed no effect of flying vertebrate exclusion on the coffee foliage beetle assemblage, but did find significant variation in abundance, species richness, and species composition of coffee foliage beetles across seasons and study sites. The increased beetle biodiversity of high-shade coffee cultivation systems has important implications both for the preservation of native biodiversity in coffee growing regions and for the control of agricultural pests such as the coffee berry borer.

Plasticity in the diet of two echinoderm species across an ecotone: microbial recycling of forest litter and bottom-up forcing of population structure

Many coastal marine populations persist across gradients in benthic productivity. In the New Zealand fjords there is a sharp gradient in available biomass between the wave-washed outer coasts, dominated by kelps, and the quiescent inner fjords, where estuarine seaweeds and terrestrial inputs predominate. In Doubtful Sound we found significant variation in abundance of macroalgal groups, the grazing sea urchin Evechinus chloroticus and the detritivorous sea cucumber Stichopus mollis, and in δ 15 N and δ 13 C of the macroalgae and consumers among 5 study sites across this gradient. Analysis of δ 15 N and δ 13 C from tissue of the 2 consumers relative to the primary carbon source pools with a mass balance model indicated that diet was primarily influenced by composition and quality of macroalgal food, except at the innermost sites, where there was evidence for terrestrial inputs. These results demonstrate that it is important to resolve relative abundance of food sources and specific iso- topic variation to resolve spatial patterns in diet from stable isotope analysis across environmental gra- dients. Isotopic analysis of E. chloroticus stomach contents from the innermost sites provided strong evidence that terrestrial detritus was being assimilated via microbial recycling (δ 15 N, -5‰ and δ 13 C, -37 ‰). Differences in δ 13 C of stomach contents versus those of tissues provided a basis to measure as- similation. There was a strong correlation between this proxy for assimilation with growth parameters among study sites across the ecotone. This analysis indicates a strong bottom-up influence on vital rates of E. chloroticus within the fjord, with links to the source-sink structure of the population.

A preliminary assessment of the invasiveness of the Indo-Pacific sponge Chalinula nematifera on coral communities from the tropical Eastern Pacific

This is the first report of a sponge that overgrows live corals in the tropical Eastern Pacific ocean. Chalinula nematifera, native from the Indo-Pacific region, is an invasive sponge recorded for the first time in 2003 on coral communities from the Isla Isabel National Park (Mexican Pacific Ocean). Later, in 2006, it was found also on coral reefs from the Cabo Pulmo National Park; 217 nautical miles far away. It has been suggested that C. nematifera was introduced as fouling on ship hulls that have arrived at Isla Isabel from the Indo-Pacific. In this paper we examined the habitat specificity and the distribution and abundance through time of C. nematifera. While there were no significant variations in abundance through time, this species showed a very high specificity for living on live corals of the genus Pocillopora (94% vs. 6% on rocks). One of the environmental parameters that may explain this specificity for ramified corals is the low light intensity inside the coral colony, which was 96% lower than outside it. Coral reefs are currently struggling with a multitude of impacts that have weakened their resilience and pushed them away from equilibrium. As a result, more attention on ecology of corals is necessary. Although the abundance of C. nematifera seems to be stable, long-term monitoring programs (including studies of growth rates and recruitment) are needed to determine if this species could represent a threat to the Mexican coral ecosystem in the future.

Upregulation of Pentraxin-3 in Human Endothelial Cells After Lysophosphatidic Acid Exposure

The earliest event in atherogenesis appears to be endothelium dysfunction. Lysophosphatidic acid (LPA), one of the major bioactive lipid components of oxidized low-density lipoproteins (oxLDL), can cause the activation of endothelial cells (ECs), which start to secrete multiple proinflammatory polypeptides/proteins. The purpose of this study was to better document the proatherogenic properties of LPA using a subproteomic approach focused on the secretome of LPA-treated ECs. The secretome of LPA-treated ECs was analyzed using the 2D-DIGE approach. Among the 20 spots displaying significant variations of abundance compared with the control cells, we identified pentraxin-3 by mass spectrometry. Pentraxin-3 upregulation was confirmed at the mRNA and protein level, both on immortalized and primary ECs. LPA- but also oxLDL-induced pentraxin-3 upregulation was reduced in the presence of an antagonist of the LPA-receptors and largely dependent on NFkappaB activation. Finally, we demonstrated, for the first time, the chemotactic activity of pentraxin-3 on human THP-1 monocytes by using a chemotaxis assay. Our findings favor the proatherogenic role of LPA, a bioactive lipid produced by activated platelets and present in oxLDL, because it enhances pentraxin-3 secretion that could contribute to the accumulation of monocytes in the atherosclerotic lesion.

Semiempirical Models of the Solar Atmosphere. II. The Quiet‐Sun Low Chromosphere at Moderate Resolution

We present a new, one-dimensional model of the solar atmosphere (called SRPM 305) at moderate angular resolution (~1''-2''). Key characteristics of the SRPM 305 model include (1) a minimum temperature of ~3800 K at a gas pressure of ~80 dyne cm-2 and (2) a rapid temperature rise above the temperature-minimum layer that results in substantial overionization of most elements when compared with LTE calculations. The model calculations reproduce the ~4300 K minimum brightness temperature of the UV continuum (between 1400-1500 Å) observed by SUMER and the ~4400 K observed minimum radio-continuum brightness temperature (between wavelengths 0.01 and 100 mm). Neither the UV nor the radio continuum bear on the low-temperature minimum value because their broad intensity contribution functions cause the higher temperatures of the upper chromospheric layers to effectively hide the low minimum temperature region. The SRPM 305 model reproduces the observed intensities of CO lines at 4.466 μm, at both the disk center and near the limb, by using C and O abundances consistent with recent literature low values. The model also reproduces observed intensities of C I spectral lines at 5381 and 8337 Å, CH lines at about 4306 Å, the CN band head at 3883 Å, and the O I lines at 7772, 7774, and 7776 Å, respectively. Using the SRPM 305 model, we find no significant abundance variations between the photosphere and the low chromosphere. Consequently, the single-component model presented here matches several apparently contradictory observations and thereby resolves the controversy about the temperature minimum value.

Stream channel geomorphology influences mussel abundance in southern Appalachian streams, U.S.A.

Summary1. Studies of North American streams have shown that hydraulic parameters and stream geomorphology can explain unionid mussel abundance at both the reach and catchment scale. However, few studies have examined applicability of hydrogeomorphic variables across broader spatial scales, such as across whole catchments, or have elucidated conditions under which spates can affect mussel populations in streams.2. We quantified freshwater mussel abundance and species richness and their physical habitat at 24 sites in eight streams in southern Appalachian catchments in 2000 and 2001. In addition, we modelled site‐specific hydraulic parameters during summer baseflow and bankfull stages to estimate high‐ and low‐discharge conditions, respectively.3. Mussel abundance was related to stream geomorphology, whereas richness was related to stream size. Baseflow habitat parameters explained only minor variation in abundance or richness, and both measures were highly correlated with mean current velocity or stream size. Bankfull shear stress composed a relatively low proportion of overall mussel habitat variability, but it accounted for significant variation in abundance and richness.4. Mussel abundance was highly variable at sites subject to low‐shear stress during spates, whereas abundance always was low at sites subject to high‐shear stress. These data suggest that habitat conditions during floods, rather than those at summer baseflow, limit the abundance of mussels in Appalachian streams. These data also suggest that mussel abundance and assemblage structure may be sensitive to any changes in channel geomorphology and hydraulic conditions that might result from land use in the catchment.