bluuebunny/crossref_metadata_2025_split huggingface dataset:
Linking forest fires to lake metabolism and carbon dioxide emissions in the boreal region of Northern Québec
Authors: MARCHAND DELPHINE , PRAIRIE YVES T. , Del GIORGIO PAUL A. 
Published: May 2009

AbstractNatural fires annually decimate up to 1% of the forested area in the boreal region of Québec, and represent a major structuring force in the region, creating a mosaic of watersheds characterized by large variations in vegetation structure and composition. Here, we investigate the possible connections between this fire‐induced watershed heterogeneity and lake metabolism and CO2 dynamics. Plankton respiration, and water–air CO2 fluxes were measured in the epilimnia of 50 lakes, selected to lie within distinct watershed types in terms of postfire terrestrial succession in the boreal region of Northern Québec. Plankton respiration varied widely among lakes (from 21 to 211 μg C L−1 day−1), was negatively related to lake area, and positively related to dissolved organic carbon (DOC). All lakes were supersaturated in CO2 and the resulting carbon (C) flux to the atmosphere (150 to over 3000 mg C m2 day−1) was negatively related to lake area and positively to DOC concentration. CO2 fluxes were positively related to integrated water column respiration, suggesting a biological component in this flux. Both respiration and CO2 fluxes were strongly negatively related to years after the last fire in the basin, such that lakes in recently burnt basins had significantly higher C emissions, even after the influence of lake size was removed. No significant differences were found in nutrients, chlorophyll, and DOC between lakes in different basin types, suggesting that the fire‐induced watershed features influence other, more subtle aspects, such as the quality of the organic C reaching lakes. The fire‐induced enhancement of lake organic C mineralization and C emissions represents a long‐term impact that increases the overall C loss from the landscape as the result of fire, but which has never been included in current regional C budgets and future projections. The need to account for this additional fire‐induced C loss becomes critical in the face of predictions of increasing incidence of fire in the circumboreal landscape.
Local adaptation to higher temperatures reduces immigration success of genotypes from a warmer region in the water flea Daphnia
Authors: VAN DOORSLAER WENDY , VANOVERBEKE JOOST , DUVIVIER CATHY , ROUSSEAUX SARAH , JANSEN MIEKE , JANSEN BASTIAAN , FEUCHTMAYR HEIDRUN , ATKINSON DAVID , MOSS BRIAN , STOKS ROBBY , DE MEESTER LUC 
Published: May 2009

AbstractThere is growing awareness that microevolutionary dynamics may alter ecological processes. Rising temperatures under global change are expected to open windows for establishment of species and genotypes from warmer regions. Yet, microevolutionary tracking of temperature change by local populations may reduce establishment success of these immigrants. We exposed a UK population of the water flea, Daphnia magna, to two temperature regimes during a 1.5‐year experimental evolution trial, and subsequently compared competitive strength of non‐warm‐adapted and warm‐adapted D. magna in competition with French genotypes. Our results indicate that local microevolutionary responses to global warming may reduce establishment success of immigrant genotypes that are preadapted to warmer climate. Simulation modeling shows that microevolution results in a reduced likelihood and speed of displacement of local populations by immigrant genotypes under realistic immigrant/resident ratios. We conclude that local evolutionary dynamics may shift the relative impact of local and regional processes in response to global change.
Changes in species richness and composition in European acidic grasslands over the past 70 years: the contribution of cumulative atmospheric nitrogen deposition
Authors: DUPRÈ CECILIA , STEVENS CARLY J. , RANKE TRAUTE , BLEEKER ALBERT , PEPPLER‐LISBACH CORD , GOWING DAVID J. G. , DISE NANCY B. , DORLAND EDU , BOBBINK ROLAND , DIEKMANN MARTIN 
Published: May 2009

AbstractOur study investigates the negative impact of nitrogen (N) deposition on species richness in acidic grasslands, based on a temporal comparison of vegetation data spanning a period of almost 70 years. We compiled a large data base of plots assigned to the Violion caninae grassland type, composed of managed, but unfertilized semi‐natural grasslands on nutrient‐poor, acidic soils. In total 1114 plots, mainly from Great Britain, the Netherlands and Germany, were compiled, dating back to 1939. Environmental site information included geographical and soil (mean Ellenberg values) variables as well as estimates of cumulative N and sulphur (S) deposition since 1939. Statistical analyses were carried out separately for the data subsets from the three regions. In all regions, the vegetation differentiation was mainly related to soil acidity and nutrient availability, as well as to the year of sampling and the cumulative amounts of N and S deposition. Plot‐species richness of vascular plants and bryophytes (analysed for Great Britain only) decreased with time and analyses suggest these are affected by various factors, notably soil pH, but also latitude and cumulative N deposition. The latter explained more of the variation in species number than the year of sampling and cumulative S deposition, which supports the interpretation that the decline in species richness is mainly caused by increasing N availability and less by altered management and soil acidification. For Great Britain and Germany, cumulative N deposition showed a strong negative relationship with several biodiversity measures, especially the proportion of dicots, whereas it was positively related to the proportion of grass species. In general, our results give temporal evidence for the negative effect of N deposition on species richness in semi‐natural vegetation.
Invasive insects impact forest carbon dynamics
Authors: CLARK KENNETH L. , SKOWRONSKI NICHOLAS , HOM JOHN 
Published: May 2009

AbstractInvasive insects can impact ecosystem functioning by altering carbon, nutrient, and hydrologic cycles. In this study, we used eddy covariance to measure net CO2exchange with the atmosphere (NEE), and biometric measurements to characterize net ecosystem productivity (NEP) in oak‐ and pine‐dominated forests that were defoliated by Gypsy moth (Lymantria disparL.) in the New Jersey Pine Barrens. Three years of data were used to compare C dynamics; 2005 with minimal defoliation, 2006 with partial defoliation of the canopy and understory in a mixed stand, and 2007 with complete defoliation of an oak‐dominated stand, and partial defoliation of the mixed and pine‐dominated stands. Previous to defoliation in 2005, annual net CO2exchange (NEEyr) was estimated at −187, −137 and −204 g C m−2 yr−1at the oak‐, mixed‐, and pine‐dominated stands, respectively. Annual NEP estimated from biometric measurements was 108%, 100%, and 98% of NEEyrin 2005 for the oak‐, mixed‐, and pine‐dominated stands, respectively. Gypsy moth defoliation strongly reduced fluxes in 2006 and 2007 compared with 2005; NEEyrwas −122, +103, and −161 g C m−2 yr−1in 2006, and +293, +129, and −17 g C m−2 yr−1in 2007 at the oak‐, mixed‐, and pine‐dominated stands, respectively. At the landscape scale, Gypsy moths defoliated 20.2% of upland forests in 2007. We calculated that defoliation in these upland forests reduced NEEyrby 41%, with a 55% reduction in the heavily impacted oak‐dominated stands. ‘Transient’ disturbances such as insect defoliation, nonstand replacing wildfires, and prescribed burns are major factors controlling NEE across this landscape, and when integrated over time, may explain much of the patterning of aboveground biomass and forest floor mass in these upland forests.
Carbon sequestration in tropical forests and water: a critical look at the basis for commonly used generalizations
Authors: MALMER ANDERS , MURDIYARSO DANIEL , (SAMPURNO) BRUIJNZEEL L. A. , ILSTEDT ULRIK 
Published: May 2009

AbstractTree planting in the tropics is conducted for a number of reasons including carbon sequestration, but often competes with increasingly scarce water resources. The basics of forest and water relations are frequently said to be well understood but there is a pressing need to better understand and predict the hydrological effects of land‐use and climate change in the complex and dynamic landscapes of the tropics. This will remain elusive without the empirical data required to feed hydrological process models. It is argued that the current state of knowledge is confused by too broad a use of the terms ‘forest’ and ‘(af)forestation’, as well as by a bias towards using data generated mostly outside the tropics and for nondegraded soil conditions. Definitions of forest, afforestation and reforestation as used in the climate change community and their application by land and water managers need to be reconciled.
El Niño and dry season rainfall influence hostplant phenology and an annual butterfly migration from Neotropical wet to dry forests
Authors: SRYGLEY ROBERT B. , DUDLEY ROBERT , OLIVEIRA EVANDRO G. , AIZPRÚA RAFAEL , PELAEZ NICOLE Z. , RIVEROS ANDRE J. 
Published: May 2009

AbstractWe censused butterflies flying across the Panama Canal at Barro Colorado Island (BCI) for 16 years and butterfly hostplants for 8 years to address the question: What environmental factors influence the timing and magnitude of migrating Aphrissa statira butterflies? The peak migration date was earlier when the wet season began earlier and when soil moisture content in the dry season preceding the migration was higher. The peak migration date was also positively associated with peak leaf flushing of one hostplant (Callichlamys latifolia) but not another (Xylophragma seemannianum). The quantity of migrants was correlated with the El Niño Southern Oscillation, which influenced April soil moisture on BCI and total rainfall in the dry season. Both hostplant species responded to El Niño with greater leaf flushing, and the number of adults deriving from or laying eggs on those new leaves was greatest during El Niño years. The year 1993 was exceptional in that the number of butterflies migrating was lower than predicted by the El Niño event, yet the dry season was unusually wet for an El Niño year as well. Thus, dry season rainfall appears to be a primary driver of larval food production and population outbreaks for A. statira. Understanding how global climate cycles and local weather influence tropical insect migrations improves the predictability of ecological effects of climate change.
Reduced early growing season freezing resistance in alpine treeline plants under elevated atmospheric CO2
Authors: MARTIN MELISSA , GAVAZOV KONSTANTIN , KÖRNER CHRISTIAN , HÄTTENSCHWILER STEPHAN , RIXEN CHRISTIAN 
Published: May 2009

AbstractThe frequency of freezing events during the early growing season and the vulnerability to freezing of plants in European high‐altitude environments could increase under future atmospheric and climate change. We tested early growing season freezing sensitivity in 10 species, from four plant functional types (PFTs) spanning three plant growth forms (PGFs), from a long‐term in situ CO2 enrichment (566 vs. 370 ppm) and 2‐year soil warming (+4 K) experiment at treeline in the Swiss Alps (Stillberg, Davos). By additionally tracking plant phenology, we distinguished indirect phenology‐driven CO2 and warming effects from direct physiology‐related effects on freezing sensitivity. The freezing damage threshold (lethal temperature 50) under ambient conditions of the 10 treeline species spanned from −6.7±0.3 °C (Larix decidua) to −9.9±0.6 °C (Vaccinium gaultherioides). PFT, but not PGF, explained a significant amount of this interspecific variation. Long‐term exposure to elevated CO2 led to greater freezing sensitivity in multiple species but did not influence phenology, implying that physiological changes caused by CO2 enrichment were responsible for the effect. The elevated CO2 effect on freezing resistance was significant in leaves of Larix, Vaccinium myrtillus, and Gentiana punctata and marginally significant in leaves of Homogyne alpina and Avenella flexuosa. No significant CO2 effect was found in new shoots of Empetrum hermaphroditum or in leaves of Pinus uncinata, Leontodon helveticus, Melampyrum pratense, and V. gaultherioides. Soil warming led to advanced leaf expansion and reduced freezing resistance in V. myrtillus only, whereas Avenella showed greater freezing resistance when exposed to warming. No effect of soil warming was found in any of the other species. Effects of elevated CO2 and soil warming on freezing sensitivity were not consistent within PFTs or PGFs, suggesting that any future shifts in plant community composition due to increased damage from freezing events will likely occur at the individual species level.
Ecological feedbacks and the evolution of resistance
Authors: Duffy Meghan A. , Forde Samantha E. 
Published: May 2009

Summary
1.
The idea that parasites can affect host diversity is pervasive, and the possibility that parasites can increase host diversity is of particular interest. In this review, we focus on diversity in the resistance of hosts to their parasites, and on the different ways in which parasites can increase or decrease this resistance diversity.
2.
Theoretically, parasites can exert many different types of selection on host populations, which each have consequences for host diversity. Specifically, theory predicts that parasites can exert negative frequency‐dependent selection (NFDS) and disruptive selection on resistance, both of which increase host diversity, as well as directional selection and stabilizing selection on resistance, both of which decrease host diversity.
3.
Despite these theoretical predictions, most biologists think of only NFDS or directional selection for increased resistance in response to parasitism. Here, we present empirical support for all of these types of selection occurring in natural populations. Interestingly, several recent studies demonstrate that there is spatiotemporal variation in the type of selection that occurs (and, therefore, in the effects of parasitism on host diversity).
4.
A key question that remains, then, is: What determines the type of parasite‐mediated selection that occurs? Theory demonstrates that the answer to this question lies, at least in part, with trade‐offs associated with resistance. Specifically, the type of evolution that occurs depends critically on the strength and shape of these trade‐offs. This, combined with empirical evidence for a strong effect of environment on the shape and strength of trade‐offs, may explain the observed spatiotemporal variation in parasite‐mediated selection.
5.
We conclude that spatiotemporal variation in parasite‐driven evolution is likely to be common, and that this variation may be driven by ecological factors. We suggest that the feedback between ecological and evolutionary dynamics in host–parasite interactions is likely to be a productive area of research. In particular, studies addressing the role of ecological factors (e.g. productivity and predation regimes) in driving the outcome of parasite‐mediated selection on host populations are warranted. Such studies are necessary if we are to understand the mechanisms underlying the observed variation in the effects of parasites on host diversity.
Expression and characterization of the periplasmic cobalamin‐binding protein of Photobacterium damselae subsp. piscicida
Authors: Boiani R , Andreoni F , Serafini G , Bianconi I , Pierleoni R , Dominici S , Gorini F , Magnani M 
Published: May 2009

AbstractCobalamin (vitamin B12) is an essential cofactor in a variety of enzymatic reactions and most prokaryotes contain transport systems to import vitamin B12. A gene coding for a periplasmic cobalamin‐binding protein of Photobacterium damselae subsp. piscicida was identified by in silico analysis of sequences from a genomic library. The open reading frame was composed of 834 bp encoding a protein of 277 amino acids. The protein showed 61% identity with the vitamin B12‐binding protein precursor of P. profundum, 53% identity with the corresponding protein of Vibrio parahaemolyticus and 43% identity with the periplasmic binding protein BtuF of Escherichia coli. The expression of the native protein was investigated in P. damselae subsp. piscicida, but BtuF was weakly expressed under normal conditions. To characterize the BtuF of P. damselae subsp. piscicida, the recombinant protein was expressed with a C‐terminal His6‐tag and purified; the molecular weight was estimated to be approximately 30 kDa. The protein does not contain any free thiol group, consistent with the view that the two cysteine residues are involved in a disulphide bond. The purified BtuF binds cyanocobalamin with an affinity constant of 6 ± 2 μm.
Neutralizing antibody levels for protection against betanodavirus infection in sevenband grouper, Epinephelus septemfasciatus (Thunberg), immunized with an inactivated virus vaccine
Authors: Yamashita H , Mori K , Kuroda A , Nakai T 
Published: May 2009

AbstractAn inactivated betanodavirus, red‐spotted grouper nervous necrosis virus (RGNNV), is a vaccine candidate for viral nervous necrosis (VNN). The present study was conducted to examine inoculation doses of the vaccine and neutralizing antibody titre levels to protect fish against VNN. Young sevenband grouper, Epinephelus septemfasciatus, averaging 25.4 g, were immunized at 25 °C water temperature by a single intraperitoneal injection of formalin‐inactivated RGNNV. Fish immunized at vaccine doses of 108.5, 108.0, 107.5, 107.0 and 106.5 TCID50 per fish produced antibodies at mean titres of 1:907, 1:511, 1:259, 1:197 and 1:96, respectively, at 20 days post‐immunization (p.i.). Neutralizing antibodies were not detected in any control fish (titre <1:80). When fish were challenged with RGNNV (105.0 and 104.0 TCID50/fish) at 20 days p.i., cumulative mortalities of the fish groups immunized with 108.5, 108.0, 107.5 and 107.0 TCID50 per fish were significantly lower than those of the control group, and the relative percent survival values were higher than 60% in fish groups immunized with 107.5 TCID50 per fish or higher doses. However, no significant differences were found in mortality between the group immunized with 106.5 TCID50 per fish and the control group. From these results, it was deduced that the minimum effective inoculation dose of the vaccine is 107.0 TCID50 per fish and the minimum mean neutralizing antibody titre giving significant protection is approximately 1:200. This antibody titre level is a possible measure of vaccine efficacy against VNN in sevenband grouper, instead of a virus challenge test.
Molecular detection of three shrimp viruses and genetic variation of white spot syndrome virus in Hainan Province, China, in 2007
Authors: Tan Y , Xing Y , Zhang H , Feng Y , Zhou Y , Shi Z‐L 
Published: May 2009

AbstractWhite spot syndrome virus (WSSV), Taura syndrome virus (TSV) and infectious hypodermal and haematopoietic necrosis virus (IHHNV) have been responsible for major pandemics affecting the shrimp farming industry. Shrimp samples were collected from eight farms in Hainan Province, China, during 2007 and analysed by polymerase chain reaction (PCR) or reverse transcriptase PCR methods to determine the prevalence of these viruses. From the eight sampling locations, only samples from one farm did not show any indication of infection with WSSV, TSV or IHHNV, while samples from one additional farm exhibited evidence of infection with TSV only. Surprisingly, evidence of co‐infection with TSV and IHHNV was found among samples at two farms while evidence of co‐infection with all three viruses (WSSV, TSV and IHHNV) was detected among shrimp samples at four farms. To further elucidate the molecular characteristics of WSSV in China, we further analysed genomic features of WSSV isolates based on the ORF23/24 variable region. From these data, we identified two novel WSSV strains which contain nucleotide deletions of 5657 and 11093 bp, respectively, when compared with the largest WSSV‐TW isolate.
Elongator mediates ABA responses, oxidative stress resistance and anthocyanin biosynthesis in Arabidopsis
Authors: Zhou Xiaofeng , Hua Deping , Chen Zhizhong , Zhou Zhengjun , Gong Zhizhong 
Published: May 2009

SummaryElongator is a histone acetyl‐transferase complex consisting of six subunits, and is highly conserved in eukaryotic organisms. Here, we isolated two novel mutants, elp2 and elp6, during a genetic screening for ABA‐hypersensitive Arabidopsis mutants. Map‐based cloning identified ELP2 and ELP6, which encode the orthologs of the yeast Elongator subunits, ELP2 and ELP6, respectively. Another Elongator subunit mutant, elp4/elo1, was obtained from the SALK T‐DNA collection. The elp1/abo1/elo2 mutant was isolated in a previous study. All four of the Elongator mutants had narrow leaves, reduced root growth, ABA hypersensitivity and an increased accumulation of anthocyanins. Mutations in the core subcomplex subunits ELP1/ABO1 and ELP2, but not in the accessory subcomplex subunits ELP4/ELO1 and ELP6, caused stomatal closing to be supersensitive to ABA. In addition, the four mutants were all more resistant than the wild type to oxidative stress produced by methyl viologen, and to CsCl. Gene expression analysis indicated that the four mutants had increased transcript levels of CAT3 under normal conditions, increased transcript levels of ZAT10 when treated with ABA and reduced transcript levels of MYBL2, which encodes a single‐repeat MYB protein, acting as a negative regulator of anthocyanin biosynthesis. Our results suggest that Elongator plays crucial roles in regulating plant responses to ABA, oxidative stress resistance and anthocyanin biosynthesis in Arabidopsis.
Functional characterization of a novel benzylisoquinoline O‐methyltransferase suggests its involvement in papaverine biosynthesis in opium poppy (Papaver somniferum L)
Authors: Pienkny Silke , Brandt Wolfgang , Schmidt Jürgen , Kramell Robert , Ziegler Jörg 
Published: May 2009

SummaryThe benzylisoquinoline alkaloids are a highly diverse group of about 2500 compounds which accumulate in a species‐specific manner. Despite the numerous compounds which could be identified, the biosynthetic pathways and the participating enzymes or cDNAs could be characterized only for a few selected members, whereas the biosynthesis of the majority of the compounds is still largely unknown. In an attempt to characterize additional biosynthetic steps at the molecular level, integration of alkaloid and transcript profiling across Papaver species was performed. This analysis showed high expression of an expressed sequence tag (EST) of unknown function only in Papaver somniferum varieties. After full‐length cloning of the open reading frame and sequence analysis, this EST could be classified as a member of the class II type O‐methyltransferase protein family. It was related to O‐methyltransferases from benzylisoquinoline biosynthesis, and the amino acid sequence showed 68% identical residues to norcoclaurine 6‐O‐methyltransferase. However, rather than methylating norcoclaurine, the recombinant protein methylated norreticuline at position seven with a Km of 44 μm using S‐adenosyl‐l‐methionine as a cofactor. Of all substrates tested, only norreticuline was converted. Even minor changes in the benzylisoquinoline backbone were not tolerated by the enzyme. Accordingly, the enzyme was named norreticuline 7–O‐methyltransferase (N7OMT). This enzyme represents a novel O‐methyltransferase in benzylisoquinoline metabolism. Expression analysis showed slightly increased expression of N7OMT in P. somniferum varieties containing papaverine, suggesting its involvement in the partially unknown biosynthesis of this pharmaceutically important compound.