Increasing land-use intensity decreases floral colour diversity of plant communities in temperate grasslands

To preserve biodiversity and ecosystem functions in a globally changing world it is crucial to understand the effect of land use on ecosystem processes such as pollination. Floral colouration is known to be central in plant-pollinator interactions. To date, it is still unknown whether land use affects the colouration of flowering plant communities. To assess the effect of land use on the diversity and composition of flower colours in temperate grasslands, we collected data on the number of flowering plant species, blossom cover and flower reflectance spectra from 69 plant communities in two German regions, Schwäbische Alb (SA) and Hainich-Dün (HD). We analysed reflectance data of flower colours as they are perceived by honeybees and studied floral colour diversity based upon spectral loci of each flowering plant species in the Maxwell triangle. Before the first mowing, flower colour diversity decreased with increasing land-use intensity in SA, accompanied by a shift of mean flower colours of communities towards an increasing proportion of white blossom cover in both regions. By changing colour characteristics of grasslands, we suggest that increasing land-use intensity can affect the flower visitor fauna in terms of visitor behaviour and diversity. These changes may in turn influence plant reproduction in grassland plant communities. Our results indicate that land use is likely to affect communication processes between plants and flower visitors by altering flower colour traits.     

Determining heparan sulfate structure in the vicinity of specific sulfotransferase recognition sites by mass spectrometry

Sulfated motifs on heparan sulfate (HS) are involved in various extracellular processes from cell signaling to enzymatic regulation, but the structures of these motifs are obscure. We have developed a strategy to determine the structure of sulfotransferase recognition sites which constitute these motifs. Stable isotope is first introduced into specific sites on HS with HS sulfotransferases and the modified HS is then digested into oligosaccharides of differing sizes. The overlapping oligosaccharides containing the introduced stable isotope are identified by changes in the m/z profiles by mass spectrometry, and their relationships are elucidated. In this way, the HS structures in the vicinity of the sulfotransferase recognition site are quickly determined and groups on precursor structures of HS that direct the action of HS sulfotransferases are pinpointed.     

Humic substances and the water calcium content change the toxicity of malachite green

Laboratory experiments were conducted to test interactive effects of calcium (Ca²⁺) content and the presence of humic substance (HS) on malachite green (MAG)‐induced toxicity in fish embryos and larvae by means of a semistatic 144‐h‐embryo‐larval‐test with zebrafish (Danio rerio). Two kinds of reconstituted water samples were used to produce the test media by mixing salts into deionized water resulting in either hard water (↑Ca ? HS), or soft water (↓Ca ? HS). By adding HS two additional test media were produced (↑Ca + HS, ↓Ca + HS). MAG was tested in concentrations of 0.05, 0.10, 0.15, 0.20, 0.25 mg L^?1. The toxicity ranking of MAG (mg L^?1) to embryos based on 96‐h‐LC₅₀ in the different test water samples is: ↑Ca ? HS (0.061) > ↑Ca + HS (0.123) = ↓Ca ? HS (0.12) ≥ ↓Ca + HS (0.134) and on 144‐h‐LC₅₀ to larvae is: ↑Ca ? HS (0.038) > ↑Ca + HS (0.06) > ↓Ca ? HS (0.077) = ↓Ca + HS (0.077). Mortality of all the groups was significantly different (P < 0.05). Increased Ca²⁺ concentrations did not protect zebrafish embryos and larvae from MAG‐induced toxicity. At high Ca²⁺ conditions, the mortality of the embryos as well as of the larvae is reduced in the ↑Ca + HS group relative to the ↑Ca ? HS group. Thus, at high Ca²⁺ conditions the HS does affect the MAG‐induced mortality. The mechanism which causes the higher toxicity of MAG in the presence of higher Ca²⁺ concentrations is poorly understood. A probable explanation could be the stimulation of the calcium‐binding protein calmodulin as well as the calmodulin kinase II in cell membranes in the presence of high Ca²⁺ concentrations.     

Mesenteric lymph from rats with trauma-hemorrhagic shock causes abnormal cardiac myocyte function and induces myocardial contractile dysfunction

Myocardial contractile dysfunction develops following trauma-hemorrhagic shock (T/HS). We have previously shown that, in a rat fixed pressure model of T/HS (mean arterial pressure of 30-35 mmHg for 90 min), mesenteric lymph duct ligation before T/HS prevented T/HS-induced myocardial contractile depression. To determine whether T/HS lymph directly alters myocardial contractility, we examined the functional effects of physiologically relevant concentrations of mesenteric lymph collected from rats undergoing trauma-sham shock (T/SS) or T/HS on both isolated cardiac myocytes and Langendorff-perfused whole hearts. Acute application of T/HS lymph (0.1-2%), but not T/SS lymph, induced dual inotropic effects on myocytes with an immediate increase in the amplitude of cell shortening (1.4 ± 0.1-fold) followed by a complete block of contraction. Similarly, T/HS lymph caused dual, positive and negative effects on cellular Ca2? transients. These effects were associated with changes in the electrophysiological properties of cardiac myocytes; T/HS lymph initially prolonged the action potential duration (action potential duration at 90% repolarization, 3.3 ± 0.4-fold), and this was followed by a decrease in the plateau potential and membrane depolarization. Furthermore, intravenous infusion of T/HS lymph, but not T/SS lymph, caused myocardial contractile dysfunction at 24 h after injection, which mimicked actual T/HS-induced changes; left ventricular developed pressure (LVDP) and the maximal rate of LVDP rise and fall (±dP/dt(max)) were decreased and inotropic response to Ca2? was blunted. However, the contractile responsiveness to β-adrenergic receptor stimulation in the T/HS lymph-infused hearts remained unchanged. These results suggest that T/HS lymph directly causes negative inotropic effects on the myocardium and that T/HS lymph-induced changes in myocyte function are likely to contribute to the development of T/HS-induced myocardial dysfunction.     

Analysis of the lung microbiome in the "healthy" smoker and in COPD

Although culture-independent techniques have shown that the lungs are not sterile, little is known about the lung microbiome in chronic obstructive pulmonary disease (COPD). We used pyrosequencing of 16S amplicons to analyze the lung microbiome in two ways: first, using bronchoalveolar lavage (BAL) to sample the distal bronchi and air-spaces; and second, by examining multiple discrete tissue sites in the lungs of six subjects removed at the time of transplantation. We performed BAL on three never-smokers (NS) with normal spirometry, seven smokers with normal spirometry ("healthy smokers", HS), and four subjects with COPD (CS). Bacterial 16 s sequences were found in all subjects, without significant quantitative differences between groups. Both taxonomy-based and taxonomy-independent approaches disclosed heterogeneity in the bacterial communities between HS subjects that was similar to that seen in healthy NS and two mild COPD patients. The moderate and severe COPD patients had very limited community diversity, which was also noted in 28% of the healthy subjects. Both approaches revealed extensive membership overlap between the bacterial communities of the three study groups. No genera were common within a group but unique across groups. Our data suggests the existence of a core pulmonary bacterial microbiome that includes Pseudomonas, Streptococcus, Prevotella, Fusobacterium, Haemophilus, Veillonella, and Porphyromonas. Most strikingly, there were significant micro-anatomic differences in bacterial communities within the same lung of subjects with advanced COPD. These studies are further demonstration of the pulmonary microbiome and highlight global and micro-anatomic changes in these bacterial communities in severe COPD patients.     

In vivo manipulation of heparan sulfate structure and its effect on Drosophila development

Heparan sulfate proteoglycans (HSPGs) participate in a wide range of biological processes through interactions with a number of ligand proteins. The nature of these interactions largely depends on the heparan sulfate (HS) moiety of HSPGs, which undergoes a series of modifications by various HS-modifying enzymes (HSMEs). Although the effects of alterations in a single HSME on physiological processes have started to be studied, it remains elusive how a combination of these molecules control the structure and function of HS. Here we systematically manipulated the HS structures and analyzed their effect on morphogenesis and signaling, using the genetically tractable model organism, Drosophila. We generated transgenic fly strains overexpressing HSMEs alone or in combination. Unsaturated disaccharide analyses of HS showed that expression of various HSMEs generates distinct HS structures, and the enzymatic activities of HSMEs are influenced by coexpression of other HSMEs. Furthermore, these transgenic HSME animals showed a different extent of lethality, and a subset of HSMEs caused specific morphological defects due to defective activities of Wnt and bone morphogenetic protein signaling. There is no obvious relationship between HS unsaturated disaccharide composition and developmental defects in HSME animals, suggesting that other structural factors, such as domain organization or sulfation sequence, might regulate the function of HS.     

Variation in Species and Trophic Composition of Insect Communities in Puerto Rico1

Insects are important participants in many ecosystem processes, but the effects of anthropogenic and natural disturbances on insect communities have been poorly studied. To describe how disturbances affect insect communities, we addressed two questions: Do insect communities return to a pre‐hurricane composition? And how do insect communities change during succession? To answer these questions, we studied insect communities in a chronosequence of two abandoned pastures (5 yr and 32 yr) and a mature forest (>80 yr) that were recently disturbed by two hurricanes (Hurricane Hugo, 1989) Hurricane Georges, 1998). Although insect abundance and richness fluctuated during the study, all sites returned to pre‐hurricane (Hurricane Georges) abundance and richness in less than one year. All trophic categories present before Hurricane Georges were present after the hurricane, but richness within categories fluctuated greatly. Insect richness did not increase during succession; the 5 yr site had the highest richness, the >80 yr site had an intermediate richness, and die 32 yr site the lowest. Nevertheless, the species composition of the two forested sites was different in comparison to the 5 yr site. These results suggest that trophic structure varies little in time and space, but the species composition within each trophic category is highly variable.     

Land‐use and fire history effects on post‐fire vegetation dynamics in eastern Spain

Question: Is post‐fire, medium‐term vegetation dynamics determined by land‐use or fire history prior to fire? Location: South‐facing slope in the Gallinera valley, Alicante province, eastern Spain. Methods: After mapping the land‐use and fire history of the study site using photo‐interpretation, we sampled vegetation structure on a set of plots representing the most frequent land‐use and fire history combinations on an area burned six years before sampling. We studied the effects of land‐use history, comparing the one‐fire land‐use trajectories. We analysed the effects of fire history; comparing one‐ and two‐fire plots for both previously cropped and uncropped areas. Results: Most variables were not significantly different between the earliest abandoned plots (abandoned at least 38 years before the fire) and the uncropped plots. On the most recently abandoned plots (abandoned between one and four years before the fire), the therophyte richness and the ratio of seeder: resprouter richness were significantly greatest. Different fire recurrences did not determine different post‐fire vegetation on either the uncropped or the early abandoned plots (all dominated by fire‐recruited seeder shrubs). The most recently abandoned plots had a lower resilience to fire. Conclusions: Land‐use history and recent pre‐fire land use, in particular, determined the post‐fire vegetation in the medium term. The vegetation composition converged during secondary succession among land‐use histories. Increasing fire recurrence had a small effect on mature plant communities, due to the combination of life‐history traits determining the response to fire of the dominant species.     

Land‐use legacies and the role of persistence traits in species recovery

Modern‐day plant communities often retain imprints of intensive past land use. Do low‐intensity land‐use practices also produce legacies? In this issue, Jonason et al. (Applied Vegetation Science) demonstrate that, 80 yrs after grassland abandonment, meadow species can recover if habitat improves. I interpret these findings in the context of the spatiotemporal processes that shape regional‐scale population dynamics.     

A unique role for 6-O sulfation modification in zebrafish vascular development

Heparan sulfate proteoglycans are important modulators of growth factor signaling in a variety of patterning processes. Secreted growth factors that play critical roles in angiogenesis bind to heparan sulfate, and this association is affected by 6-O-sulfation of the heparan sulfate chains. Addition of 6-O-sulfate is catalyzed by a family of sulfotransferases (HS6STs), and genetic manipulation of their function permits an assessment of their contribution to vascular assembly. We report on the biochemical activity and expression patterns of two zebrafish HS6ST genes. In situ hybridization reveals dynamic and distinct expression patterns of these two genes during development. Structural analysis of heparan sulfate from wild-type and morpholino antisense 'knockdown' embryos suggests that HS6ST-1 and HS6ST-2 have similar biochemical activity. HS6ST-2, but not HS6ST-1, morphants exhibit abnormalities in the branching morphogenesis of the caudal vein during embryonic development of the zebrafish. Our finding that HS6ST-2 is required for the branching morphogenesis of the caudal vein is the first in vivo evidence for an essential role of a gene encoding a heparan sulfate modifying enzyme in vertebrate angiogenesis. Our analysis of two zebrafish HS6ST genes suggests that a wide range of biological processes may be regulated by an array of sulfation-modifying enzymes in the vertebrate genome.     

Soil bacterial diversity in degraded and restored lands of Northeast Brazil

Land degradation deteriorates biological productivity and affects environmental, social, and economic sustainability, particularly so in the semi-arid region of Northeast Brazil. Although some studies exist reporting gross measures of soil microbial parameters and processes, limited information is available on how land degradation and restoration strategies influence the diversity and composition of soil microbial communities. In this study we compare the structure and diversity of bacterial communities in degraded and restored lands in Northeast Brazil and determine the soil biological and chemical properties influencing bacterial communities. We found that land degradation decreased the diversity of soil bacteria as indicated by both reduced operational taxonomic unit (OTU) richness and Shannon index. Soils under native vegetation and restoration had significantly higher bacterial richness and diversity than degraded soils. Redundancy analysis revealed that low soil bacterial diversity correlated with a high respiratory quotient, indicating stressed microbial communities. By contrast, soil bacterial communities in restored land positively correlated with high soil P levels. Importantly, however, we found significant differences in the soil bacterial community composition under native vegetation and in restored land, which may indicate differences in their functioning despite equal levels of bacterial diversity.     

Estuarine fish communities respond to climate variability over both river and ocean basins

Estuaries are dynamic environments at the land–sea interface that are strongly affected by interannual climate variability. Ocean–atmosphere processes propagate into estuaries from the sea, and atmospheric processes over land propagate into estuaries from watersheds. We examined the effects of these two separate climate‐driven processes on pelagic and demersal fish community structure along the salinity gradient in the San Francisco Estuary, California, USA. A 33‐year data set (1980–2012) on pelagic and demersal fishes spanning the freshwater to marine regions of the estuary suggested the existence of five estuarine salinity fish guilds: limnetic (salinity = 0–1), oligohaline (salinity = 1–12), mesohaline (salinity = 6–19), polyhaline (salinity = 19–28), and euhaline (salinity = 29–32). Climatic effects propagating from the adjacent Pacific Ocean, indexed by the North Pacific Gyre Oscillation (NPGO), affected demersal and pelagic fish community structure in the euhaline and polyhaline guilds. Climatic effects propagating over land, indexed as freshwater outflow from the watershed (OUT), affected demersal and pelagic fish community structure in the oligohaline, mesohaline, polyhaline, and euhaline guilds. The effects of OUT propagated further down the estuary salinity gradient than the effects of NPGO that propagated up the estuary salinity gradient, exemplifying the role of variable freshwater outflow as an important driver of biotic communities in river‐dominated estuaries. These results illustrate how unique sources of climate variability interact to drive biotic communities and, therefore, that climate change is likely to be an important driver in shaping the future trajectory of biotic communities in estuaries and other transitional habitats.     

SOLUBILIZATION AND PHYSICOCHEMICAL CHARACTERIZATION OF RAT BRAIN ACETYLCHOLINESTERASE: DEVELOPMENT AND MATURATION OF ITS MOLECULAR FORMS

Abstract— We have solubilized two active molecular forms of AChE from rat brain and compared them to the molecular forms solubilized from rat muscle. One of these forms, in muscle, as well as in brain, is easy to solubilize without detergent (ES form–apparent sedimentation coefficient without detergent: 4.6s); the other is hard to solubilize and we obtained a nearly total solubilization only in the presence of detergent (HS form–apparent sedimentation coefficient in presence of detergent: 10.3s). These two molecular forms are glycoprotein in nature. They interact with detergent (Triton X-100), as demonstrated by a comparison of their hydrodynamic parameters (determined by sucrose gradient centrifugation and molecular filtration) in the presence and absence of detergent. In the absence of detergent, their molecular weights are 115,000 for the ES form and 435,000 for the HS form. We did not find the molecular form in brain which seems to be specific to the muscle endplate region. at any stage of its development (EP form–solubilized by detergent–apparent s value in presence of detergent: 16.2s).
During development or maturation of the rat brain, the relative proportion of the HS form to the ES form increases; its absolute amount also increases (by more than a factor of 7 during the first month after birth). The ES form seems to be established at its adult level at the time of birth, before the large increase in the HS form. The proportion of each form in the adult rat brain remains constant: 90% of the total activity is represented by the HS form.     

Fungal infection alters the selection,dispersal and drift processes structuring the amphibian skin microbiome

Symbiotic microbial communities are important for host health, but the processes shaping these communities are poorly understood. Understanding how community assembly processes jointly affect microbial community composition is limited because inflexible community models rely on rejecting dispersal and drift before considering selection. We developed a flexible community assembly model based on neutral theory to ask: How do dispersal, drift and selection concurrently affect the microbiome across environmental gradients? We applied this approach to examine how a fungal pathogen affected the assembly processes structuring the amphibian skin microbiome. We found that the rejection of neutrality for the amphibian microbiome across a fungal gradient was not strictly due to selection processes, but was also a result of species‐specific changes in dispersal and drift. Our modelling framework brings the qualitative recognition that niche and neutral processes jointly structure microbiomes into quantitative focus, allowing for improved predictions of microbial community turnover across environmental gradients.     

Role of peroxynitrite in the responses induced by heat stress in tobacco BY-2 cultured cells

Temperatures above the optimum are sensed as heat stress (HS) by all living organisms and represent one of the major environmental challenges for plants. Plants can cope with HS by activating specific defense mechanisms to minimize damage and ensure cellular functionality. One of the most common effects of HS is the overproduction of reactive oxygen and nitrogen species (ROS and RNS). The role of ROS and RNS in the regulation of many plant physiological processes is well established. On the contrary, in plants very little is known about the physiological role of peroxynitrite (ONOO^?), the RNS species generated by the interaction between NO and O₂^?. In this work, the role of ONOO^? on some of the stress responses induced by HS in tobacco BY-2 cultured cells has been investigated by measuring these responses both in the presence and in the absence of 2,6,8-trihydroxypurine (urate), a specific scavenger of ONOO^?. The obtained results suggest a potential role for ONOO^? in some of the responses induced by HS in tobacco cultured cells. In particular, ONOO^? seems implicated in a form of cell death showing apoptotic features and in the regulation of the levels of proteins involved in the response to stress.     

Tinkering with heparan sulfate sulfation to steer development

Heparan sulfate (HS) proteoglycans, at the cell surface and extracellular matrix, facilitate ligand-receptor interactions crucial to many physiological processes. The distinct sulfation patterns of HS sugar chains presented by their protein core are key to HS proteoglycan activity. Tight regulation of several Golgi complex enzyme families is crucial to produce complex tissue-specific HS sequences. Several in vivo models deficient in HS biosynthesis enzymes demonstrate that developmental abnormalities result from modified HS structure. This review will discuss the plasticity of sulfation requirements on HS for activating protein ligands, which might reflect a flexible HS biosynthetic mechanism. In addition, the latest discovery of HS acting enzymes, the Sulfs, responsible for extracellular tweaking of HS sulfation levels subsequent to biosynthesis will be considered.     

Changes in the roles of spatial and environmental processes in the structuring of rodent metacommunities

We studied the role of spatial (regional) and environmental (local) processes in the structuring of rodent metacommunities in three contiguous ecoregions that share the same species pool. The two northern ecoregions are mainly affected by anthropogenic processes (agriculture and urbanization) while the southern one is mainly affected by natural processes (flood and drought pulses). Local communities were described based on the analysis of 77 samples of barn owl pellets. To identify which processes (patch dynamics, species sorting, mass effect or neutral theory) structure each metacommunity we evaluated the percentage of variance explained by space (spatial arrangement of communities) and environment (topography, climate and land cover) in three Variation Partitioning Redundancy Analyses. The percentage of variance in rodent metacommunities composition explained by space and environment was between 38 and 61%, and was significant in all three analyses. The pure space fraction was significant for two of the three ecoregions, while the pure environmental fraction was significant for all three ecoregions. The processes that structure rodent metacommunities change across the region. In all three ecoregions the species sorting played a key role, while, mass effect was a structuring factor for northern metacommunities. These results can be explained by species-specific dispersal characteristics and environmental filtering.     

Response diversity,nonnative species,and disassembly rules buffer freshwater ecosystem processes from anthropogenic change

Integrating knowledge of environmental degradation, biodiversity change, and ecosystem processes across large spatial scales remains a key challenge to illuminating the resilience of earth's systems. There is now a growing realization that the manner in which communities will respond to anthropogenic impacts will ultimately control the ecosystem consequences. Here, we examine the response of freshwater fishes and their nutrient excretion – a key ecosystem process that can control aquatic productivity – to human land development across the contiguous United States. By linking a continental‐scale dataset of 533 fish species from 8100 stream locations with species functional traits, nutrient excretion, and land remote sensing, we present four key findings. First, we provide the first geographic footprint of nutrient excretion by freshwater fishes across the United States and reveal distinct local‐ and continental‐scale heterogeneity in community excretion rates. Second, fish species exhibited substantial response diversity in their sensitivity to land development; for native species, the more tolerant species were also the species contributing greater ecosystem function in terms of nutrient excretion. Third, by modeling increased land‐use change and resultant shifts in fish community composition, land development is estimated to decrease fish nutrient excretion in the majority (63%) of ecoregions. Fourth, the loss of nutrient excretion would be 28% greater if biodiversity loss was random or 84% greater if there were no nonnative species. Thus, ecosystem processes are sensitive to increased anthropogenic degradation but biotic communities provide multiple pathways for resistance and this resistance varies across space.     

Analysis of land consolidation projects and their impact on land use change,landscape structure,and agricultural land resource protection: case studies of Pilsen-South and Pilsen-North (Czech Republic)

Within the countries of the former socialist bloc, the changes in the politico-economic system at the end of the 1990s created a situation where it was (and still is) necessary to restore agricultural land resource property rights, to adjust the structure of agricultural land to current needs and to improve the current state of environmental resources. This case study covers 19 cadastral areas in the western part of the Czech Republic that were affected by the land consolidation process during 2000–2006. The main task of this study was to document how land consolidation processes could affect the change of land use and landscape structure and whether the land consolidation planners take into account the protection of natural resources. The increased acreage of grasslands was the most important change which has occurred in the land use in the 19 analysed cadastral areas, before and after land consolidations. In the studied area, the changes of land use involved 6.8 % of the total land consolidation area. This area of grassland significantly increased the protection of agricultural land from water erosion. In terms of changes in the landscape structure, the construction of new field road networks is the most important result. The results confirm the importance of land consolidation processes not only for the organization and recovery of ownership and cadastral records but also for the improvement of agricultural use of landscape and protection of natural resources such as soil, water and plant and animal communities.