bluuebunny/crossref_metadata_2025_split huggingface dataset:
Assessing the response of area burned to changing climate in western boreal North America using a Multivariate Adaptive Regression Splines (MARS) approach
Authors: BALSHI MICHAEL S. , McGUIRE A. DAVID , DUFFY PAUL , FLANNIGAN MIKE , WALSH JOHN , MELILLO JERRY 
Published: July 2008

AbstractFire is a common disturbance in the North American boreal forest that influences ecosystem structure and function. The temporal and spatial dynamics of fire are likely to be altered as climate continues to change. In this study, we ask the question: how will area burned in boreal North America by wildfire respond to future changes in climate? To evaluate this question, we developed temporally and spatially explicit relationships between air temperature and fuel moisture codes derived from the Canadian Fire Weather Index System to estimate annual area burned at 2.5° (latitude × longitude) resolution using a Multivariate Adaptive Regression Spline (MARS) approach across Alaska and Canada. Burned area was substantially more predictable in the western portion of boreal North America than in eastern Canada. Burned area was also not very predictable in areas of substantial topographic relief and in areas along the transition between boreal forest and tundra. At the scale of Alaska and western Canada, the empirical fire models explain on the order of 82% of the variation in annual area burned for the period 1960–2002. July temperature was the most frequently occurring predictor across all models, but the fuel moisture codes for the months June through August (as a group) entered the models as the most important predictors of annual area burned. To predict changes in the temporal and spatial dynamics of fire under future climate, the empirical fire models used output from the Canadian Climate Center CGCM2 global climate model to predict annual area burned through the year 2100 across Alaska and western Canada. Relative to 1991–2000, the results suggest that average area burned per decade will double by 2041–2050 and will increase on the order of 3.5–5.5 times by the last decade of the 21st century. To improve the ability to better predict wildfire across Alaska and Canada, future research should focus on incorporating additional effects of long‐term and successional vegetation changes on area burned to account more fully for interactions among fire, climate, and vegetation dynamics.
Reappraisal of drying and wetting effects on C and N mineralization and fluxes in soils
Authors: BORKEN WERNER , MATZNER EGBERT 
Published: July 2008

AbstractIn the next decades, many soils will be subjected to increased drying/wetting cycles or modified water availability considering predicted global changes in precipitation and evapotranspiration. These changes may affect the turnover of C and N in soils, but the direction of changes is still unclear. The aim of the review is the evaluation of involved mechanisms, the intensity, duration and frequency of drying and wetting for the mineralization and fluxes of C and N in terrestrial soils. Controversial study results require a reappraisal of the present understanding that wetting of dry soils induces significant losses of soil C and N. The generally observed pulse in net C and N mineralization following wetting of dry soil (hereafter wetting pulse) is short‐lived and often exceeds the mineralization rate of a respective moist control. Accumulated microbial and plant necromass, lysis of live microbial cells, release of compatible solutes and exposure of previously protected organic matter may explain the additional mineralization during wetting of soils. Frequent drying and wetting diminishes the wetting pulse due to limitation of the accessible organic matter pool. Despite wetting pulses, cumulative C and N mineralization (defined here as total net mineralization during drying and wetting) are mostly smaller compared with soil with optimum moisture, indicating that wetting pulses cannot compensate for small mineralization rates during drought periods. Cumulative mineralization is linked to the intensity and duration of drying, the amount and distribution of precipitation, temperature, hydrophobicity and the accessible pool of organic substrates. Wetting pulses may have a significant impact on C and N mineralization or flux rates in arid and semiarid regions but have less impact in humid and subhumid regions on annual time scales. Organic matter stocks are progressively preserved with increasing duration and intensity of drought periods; however, fires enhance the risk of organic matter losses under dry conditions. Hydrophobicity of organic surfaces is an important mechanism that reduces C and N mineralization in topsoils after precipitation. Hence, mineralization in forest soils with hydrophobic organic horizons is presumably stronger limited than in grassland or farmland soils. Even in humid regions, suboptimal water potentials often restrict microbial activity in topsoils during growing seasons. Increasing summer droughts will likely reduce the mineralization and fluxes of C and N whereas increasing summer precipitation could enhance the losses of C and N from soils.
Neuroendocrine ductal carcinoma in situ (NE‐DCIS) of the breast – comparative clinicopathological study of 20 NE‐DCIS cases and 274 non‐NE‐DCIS cases
Authors: Kawasaki T , Nakamura S , Sakamoto G , Murata S , Tsunoda‐shimizu H , Suzuki K , Takahashi O , Nakazawa T , Kondo T , Katoh R 
Published: July 2008

Aims:  To clarify the clinicopathological significance of breast neuroendocrine ductal carcinoma in situ (NE‐DCIS), i.e. DCIS in which >50% of cells immunohistochemically express NE markers (chromogranin A and/or synaptophysin), 20 NE‐DCIS were studied and the findings compared with those of 274 non‐NE‐DCIS.Methods and results:  NE‐DCIS accounted for 6.8% of all DCIS. Mean patient age was 50.4 years for NE‐DCIS and 49.6 years for non‐NE‐DCIS (P = 0.66). The main clinical presentation of NE‐DCIS was a bloody nipple discharge, seen in 72%, significantly different from the 5% in non‐NE‐DCIS cases (P < 0.01). Carcinoma was preoperatively diagnosed in 67% of NE‐DCIS and 95% of non‐NE‐DCIS cases (P < 0.01). NE‐DCIS was histologically characterized by a predominantly solid growth of cancer cells with fine‐granular cytoplasm and ovoid, or occasionally spindle‐shaped nuclei. A well‐developed vascular network was also common. Nuclear grades and Van Nuys classification were significantly lower for NE‐DCIS than for non‐NE‐DCIS (P < 0.01). The mean MIB‐1 labelling index was 4.3% in NE‐DCIS and 8.1% in non‐NE‐DCIS (P < 0.01). Furthermore, NE‐DCIS cases had significantly higher oestrogen and progesterone receptor and lower HER2 scores than non‐NE‐DCIS cases (P < 0.01).Conclusions:  NE‐DCIS has characteristic clinicopathological features and can, therefore, be regarded as a distinct variant of DCIS.
AR CAG repeat length is not associated with serum gonadal steroids and lipid levels in healthy men
Authors: Goutou Maria , Sakka Christina , Stakias Nikos , Stefanidis Ioannis , Koukoulis Georgios N. 
Published: July 2008

SummaryCardiovascular risk factors seem to be affected by androgens, which exert their action through the androgen receptor (AR). Androgenic action correlates inversely with a polymorphic CAG repeat region in the AR gene encoding for glutamine residues the length of which appears to influence high density lipoprotein (HDL) cholesterol levels. The aim of the study was to investigate the possible association between AR gene polymorphism and serum sex steroids and lipids. 170 healthy males, aged 22–59 years (mean 42 years), were included in the study. Anthropometrical as well as sociometrical parameters were recorded. Body fat content (BFC) (% fat mass) was measured by bioelectrical impedance. Serum lipids and total and free testosterone (T) and estradiol (E2) levels were measured in each subject. AR gene CAG repeats length was determined. No significant correlation was found between the length of AR gene polyglutamine tract and the levels of gonadal steroids (total and free T, total and free E2) or to the lipid levels (Triglycerides, total, HDL and LDL cholesterol). In addition, serum lipid levels were not significantly different in the lower compared to higher half of CAG repeats length distribution. On multiple regression analysis BFC was found to predict HDL‐cholesterol and triglycerides were found to show, respectively, significant negative and positive correlation with body fat content. In conclusion, AR gene polymorphism may not predict sex steroid levels in healthy males. Possible impact of CAG repeats length on lipids profile has not been established.
Linking seasonal distribution patterns with prey availability in a central‐place forager, the Steller sea lion
Authors: Womble Jamie N. , Sigler Michael F. , Willson Mary F. 
Published: July 2008

AbstractAim We used a novel approach to infer foraging areas of a central‐place forager, the Steller sea lion (Eumetopias jubatus), by assessing changes in the temporal and spatial distribution patterns of sea lions at terrestrial sites. Specifically, our objectives were (1) to classify seasonal distribution patterns of Steller sea lions and (2) to determine to what extent the seasonal distribution of Steller sea lions is explained by seasonal concentrations of prey.Location Southeast Alaska, USA.Methods Steller sea lions of all age classes were counted monthly (2001–04) by aerial surveys at 28 terrestrial sites. Hierarchical cluster analysis and principal components analysis were used to classify seasonal distribution patterns of Steller sea lions at these terrestrial sites. We estimated the proportion of sea lions in the study area that were associated with each seasonal distribution pattern.Results Multivariate ordination techniques revealed four distinct seasonal distributional patterns. During December, 55% of the sea lions in the study area were found at Type 1 sites, located near over‐wintering herring aggregations. During May, 56% of sea lions were found at Type 2 sites, near aggregations of spring‐spawning forage fish. In July, 78% of sea lions were found at Type 3 sites, near summer migratory corridors of salmon. During September, 44% of sea lions were found at Type 4 sites, near autumn migratory corridors of salmon.Main conclusions Seasonal attendance patterns of sea lions were commonly associated with the seasonal availability of prey species near terrestrial sites and reflected seasonal foraging patterns of Steller sea lions in Southeast Alaska. A reasonable annual foraging strategy for Steller sea lions is to forage on herring (Clupea pallasii) aggregations in winter, spawning aggregations of forage fish in spring, salmon (Oncorhynchusspp.) in summer and autumn, and pollock (Theragra chalcogramma) and Pacific hake (Merluccius productus) throughout the year. The seasonal use of haulouts by sea lions and ultimately haulout‐specific foraging patterns of Steller sea lions depend in part upon seasonally available prey species in each region.
Surviving out in the cold: Antarctic endemic invertebrates and their refugia
Authors: Pugh P. J. A. , Convey P. 
Published: July 2008

AbstractAim  To identify Antarctic palaeoendemic taxa and their probable glacial refugia from regional groups of endemic species records.Location  Antarctica.Methods  We compiled a list of Antarctic non‐marine invertebrates from published literature, and then deleted all records relating to non‐endemic, zoochoric (phoretic and parasitic), marine and partially identified species to leave only the elements endemic to Antarctica. We then used cluster analysis and principal components analysis to identify regional groupings within this endemic fauna.Results  Some 170+ of the reported 520+ Antarctic invertebrates are free‐living and endemic, but only nine of these are pan‐Antarctic, with the majority having either ‘continental’/eastern or ‘maritime’/western distributions.Main conclusions  All invertebrates endemic to continental Antarctica are confined to, or found adjacent to, ice‐free palaeorefugial mountains, nunataks and coastal exposures. By contrast, only one maritime Antarctic palaeorefugium has been identified, and most endemic taxa are currently associated with coastal lowland neorefugia. We suggest which regions of Antarctica (1) are likely to be refugial, and (2) simply require more data in order that the nature and origin of their fauna can be elucidated.
Population genomics: a new generation of genome scans to bridge the gap with functional genomics
Authors: BONIN AURÉLIE 
Published: July 2008

AbstractPopulation genomics is an increasingly popular approach to investigate the genetic basis of adaptation and speciation at the genome scale. However, it has so far largely failed to go beyond the mere identification of anonymous markers displaying selection signatures. Will population genomics ever be up to our expectations and able to really pinpoint genes underlying adaptation and speciation processes? In this issue of Molecular Ecology, Namroud et al. use population genomics to investigate local adaptation in natural populations of a conifer tree, the white spruce (Picea glauca). They show how population and functional genomics can finally converge with the deployment of the next generation of genome scans, which target gene‐rich regions rather than the whole genome.
Silencing jasmonate signalling and jasmonate‐mediated defences reveals different survival strategies between two Nicotiana attenuata accessions
Authors: STEPPUHN ANKE , SCHUMAN MEREDITH C. , BALDWIN IAN T. 
Published: July 2008

AbstractTo determine the impact of genotypic variation in secondary metabolite production on antiherbivore resistance and plant fitness, we genetically silenced biosynthetic genes for nicotine, trypsin proteinase inhibitors (TPI), and jasmonate (JA) production in two accessions of Nicotiana attenuata: one from Utah (UT) which responds to herbivory with JA‐induced nicotine and TPI production, and one from Arizona (AZ) which is TPI‐deficient but also produces JA‐induced nicotine. Transient silencing of JA biosynthesis increased Manduca sexta larval growth on wild type (WT) plants of both accessions, but not on TPI‐deficient UT or nicotine‐deficient AZ lines, demonstrating that JA‐mediated resistance to M. sexta requires TPIs in the UT and nicotine in the naturally TPI‐deficient AZ accession. When transplanted into a native UT population, AZ and UT plants, rendered equally able or unable to produce nicotine and TPIs by stable transformation, received significantly different levels of herbivory. Both accessions differed in their resistance depending on the type of herbivores: resistance to rare, voracious herbivores (Saltatoria and Mammalia) was greater in AZ than UT lines, and dependent on nicotine production, while resistance to small, abundant herbivores (Coleoptera and Thysanoptera) was greater in UT lines, and dependent on TPI production. AZ lines produced more flowers and seed capsules than UT lines independently of TPI production costs. This fitness advantage was lost when accessions did not produce nicotine. We conclude that these two accessions have developed different survival strategies and thus differ in the cost‐benefit functions of their JA‐mediated defences.
Endoparasitism in cereal aphids: molecular analysis of a whole parasitoid community
Authors: TRAUGOTT M. , BELL J. R. , BROAD G. R. , POWELL W. , VAN VEEN F. J. F. , VOLLHARDT I. M. G. , SYMONDSON W. O. C. 
Published: July 2008

AbstractInsect parasitoids play a major role in terrestrial food webs as they are highly diverse, exploit a wide range of niches and are capable of affecting host population dynamics. Formidable difficulties are encountered when attempting to quantify host–parasitoid and parasitoid–parasitoid trophic links in diverse parasitoid communities. Here we present a DNA‐based approach to effectively track trophic interactions within an aphid–parasitoid food web, targeting, for the first time, the whole community of parasitoids and hyperparasitods associated with a single host. Using highly specific and sensitive multiplex and singleplex polymerase chain reaction, endoparasitism in the grain aphid Sitobion avenae (F) by 11 parasitoid species was quantified. Out of 1061 aphids collected during 12 weeks in a wheat field, 18.9% were found to be parasitized. Parasitoids responded to the supply of aphids, with the proportion of aphids parasitized increasing monotonically with date, until the aphid population crashed. In addition to eight species of primary parasitoids, DNA from two hyperparasitoid species was detected within 4.1% of the screened aphids, with significant hyperparasitoid pressure on some parasitoid species. In 68.2% of the hyperparasitized aphids, identification of the primary parasitoid host was also possible, allowing us to track species‐specific parasitoid‐hyperparasitoid links. Nine combinations of primary parasitoids within a single host were found, but only 1.6% of all screened aphids were multiparasitized. The potential of this approach to parasitoid food web research is discussed.
Genetics of sprouting: effects of long‐term persistence in fire‐prone ecosystems
Authors: PREMOLI ANDREA C. , STEINKE LINA 
Published: July 2008

AbstractFire functional traits (postfire resprouting and seeding) are considered to be adaptations for persisting in fire‐prone environments. Although ecological and evolutionary consequences of sprouting have been extensively discussed, within‐species genetic variability and structure are unknown. Here we report levels and distribution patterns of genetic polymorphisms in postfire stands of the predominant sprouter Nothofagus antarctica. Fresh foliage of 50 individuals was collected following a spatially explicit sampling design for isozyme analysis from two replicates of each of four habitat types inhabited by the species in northwestern Patagonia, Argentina: matorral, high elevation, forest, and temporally flooded basins. Average polymorphism per population ranged from 44% to 78% and mean gene diversity per site HS varied from 0.187 to 0.274. These results show that sprouter populations hold considerable genetic variation. Significant genetic structure over short distances (< 50 m) was found at all locations. Ancient fine‐scale genetic structure is preserved by occasional seedling establishment that results in high co‐ancestry coefficients. Sprouter populations growing in suboptimal habitats such as matorral, high elevation or basins consist of pairs of heterozygous genets that occur at larger spatial scales as a result of micro‐environmental heterogeneity and/or local competition between near neighbour genotypes. In contrast, homozygous pairs of individuals for distinct isozyme loci occurred at larger spatial scales in forest stands. This indicates that biparental inbreeding due to local propagule establishment may take place to some extent in sprouters growing under favourable conditions. Our results show that sprouters follow a long‐lasting genet persistence strategy which most probably is selected under unpredictable disturbance regimes, such as fire.
tRNA and protein methylase complexes mediate zymocin toxicity in yeast
Authors: Studte Patrick , Zink Sabrina , Jablonowski Daniel , Bär Christian , Von Der Haar Tobias , Tuite Mick F. , Schaffrath Raffael 
Published: July 2008

SummaryModification of Saccharomyces cerevisiae tRNA anticodons at the wobble uridine (U34) position is required for tRNA cleavage by the zymocin tRNase killer toxin from Kluyveromyces lactis. Hence, U34 modification defects including lack of the U34 tRNA methyltransferase Trm9 protect against tRNA cleavage and zymocin. Using zymocin as a tool, we have identified toxin‐resistant mutations in TRM9 that are likely to affect the U34 methylation reaction. Most strikingly, C‐terminal truncations in Trm9 abolish interaction with Trm112, a protein shown to individually purify with Lys9 and two more methylases, Trm11 and Mtq2. Downregulation of a GAL1‐TRM112 allele protects against zymocin whereas LYS9, TRM11 and MTQ2 are dosage suppressors of zymocin. Based on immune precipitation studies, the latter scenario correlates with competition for Trm112 and in excess, some of these Trm112 partners interfere with formation of the toxin‐relevant Trm9·Trm112 complex. In contrast to trm11Δ or lys9Δ cells, trm112Δ and mtq2Δ null mutants are zymocin resistant. In line with the identified role that methylation of Sup45 by Mtq2 has for translation termination by the release factor dimer Sup45·Sup35, we observe that SUP45 overexpression and sup45 mutants suppress zymocin. Intriguingly, this suppression correlates with upregulated levels of tRNA species targeted by zymocin's tRNase activity.
NAC transcription factors NST1 and NST3 regulate pod shattering in a partially redundant manner by promoting secondary wall formation after the establishment of tissue identity
Authors: Mitsuda Nobutaka , Ohme‐Takagi Masaru 
Published: July 2008

SummaryThree distinct pattern elements of the silique are thought to contribute to its dehiscence: a separation layer, cells with a secondary wall adjacent to the separation layer, and a valve endocarp layer with secondary wall. However, the role of the secondary wall has not been proven, and the factors that regulate its formation in siliques remain to be characterized. We show here that secondary wall formation in siliques is necessary for dehiscence, and that two plant‐specific transcription factors, NAC SECONDARY WALL THICKENING PROMOTING FACTOR 1 and 3 (NST1 and NST3), regulate its formation in siliques of Arabidopsis. The promoters of the NST1 and NST3 genes were active in the valve endocarp layer and in cells surrounding vascular vessels in the replum, and NST1 promoter activity only was faintly detectable at valve margins. In nst1 mutants, specific loss of secondary walls was evident at valve margins, while nst1 nst3 double mutants lacked secondary walls in all parts of the siliques, with the exception of vascular vessels. These siliques were similarly indehiscent. The promoters of two tissue‐identity genes, INDEHISCENT (IND) and SHATTERPROOF2 (SHP2), were as active in the nst1 nst3 mutant as in the wild‐type. Moreover, the ectopic secondary wall formation that occurs in the fruitfull (ful) mutant was absent in the ful nst1 double mutant. We propose that secondary walls in valve margins are required for dehiscence, and that NST1 and NST3 regulate their formation in siliques in a partially redundant manner after the establishment of tissue identity.
CLB19, a pentatricopeptide repeat protein required for editing of rpoA and clpP chloroplast transcripts
Authors: Chateigner‐Boutin Anne‐Laure , Ramos‐Vega Maricela , Guevara‐García Arturo , Andrés Charles , De La Luz Gutiérrez‐Nava María , Cantero Araceli , Delannoy Etienne , Jiménez Luis Felipe , Lurin Claire , Small Ian , León Patricia 
Published: July 2008

SummaryRNA editing changes the sequence of many transcripts in plant organelles, but little is known about the molecular mechanisms determining the specificity of the process. In this study, we have characterized CLB19 (also known as PDE247), a gene that is required for editing of two distinct chloroplast transcripts, rpoA and clpP. Loss‐of‐function clb19 mutants present a yellow phenotype with impaired chloroplast development and early seedling lethality under greenhouse conditions. Transcript patterns are profoundly affected in the mutant plants, with a pattern entirely consistent with a defect in activity of the plastid‐encoded RNA polymerase. CLB19 encodes a pentatricopeptide repeat protein similar to the editing specificity factors CRR4 and CRR21, but, unlike them, is implicated in editing of two target sites.