bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of enamel preparation method on in vitro marginal microleakage of a flowable composite used as pit and fissure sealant
Authors: YOUSSEF M. N. , YOUSSEF F. A. , SOUZA‐ZARONI W. C. , TURBINO M. L. , VIEIRA M. M. F. 
Published: June 2006

Summary.  Objectives.  The aim of this in vitro study was to evaluate the microleakage in occlusal surfaces, after preparation with Er:YAG laser and compared to the diamond‐bur conventional technique.Methods.  Thirty premolars were divided into three groups: I – high‐speed handpiece + 37% phosphoric acid; II – Er:YAG laser (350 mJ, 4 Hz and 112 J/cm2) + 37% phosphoric acid; and III – Er:YAG laser (350 mJ, 4 Hz and 112 J/cm2) + Er:YAG laser (80 mJ, 4 Hz, and 25 mJ/cm2). All cavities received the same adhesive system and were restored with flowable composite according to manufacturer's instructions. Teeth were submitted to thermal cycling and immersed in 50% silver nitrate solutions for 8 h in total darkness. Specimens were sectioned longitudinally in the bucco‐lingual direction, in slices of 1 mm thick. Each slice was immersed into photo developing solution and was photographed, and microleakage was scored from 0 to 7, by three calibrated examiners.Results.  A statistically significant difference (P < 0·0001) was observed between Er:YAG laser prepared and etched specimens and those in the other groups.Conclusions.  It can be concluded that no significant difference was noted between the two types of enamel preparation when etching was performed. Preparing and treating the enamel surface exclusively by Er:YAG laser resulted in the highest degree of leakage.
Asymmetric coexistence: bidirectional abiotic and biotic effects between goose barnacles and mussels
Authors: KAWAI TAKASHI , TOKESHI MUTSUNORI 
Published: June 2006

SummarySpecies coexistence depends on the net effect of interacting species, representing the sum of multiple interaction components that may act simultaneously and vary independently depending on ambient environmental conditions. Consequently, for a comprehensive understanding of the compound nature of species interactions and coexistence, a mechanistic approach that allows a separate evaluation of each interaction component is required.Two sessile filter‐feeders, the goose barnacleCapitulum mitellaand the musselSeptifer virgatus, coexist on moderately wave‐exposed rocky shores in south‐western Japan. In the upper intertidal,Capitulumpositively influencedSeptifersurvivorship and growth through amelioration of thermal stress and of physical disturbance. On the other hand, these species are potential competitors as they have similar body sizes and modes of resource utilization. These opposite processes, facilitation and competition, are based on abiotic characteristics and biotic functions of the two species, respectively.In order to quantify the bidirectional abiotic, biotic and net effects, a series of experimental manipulations was conducted involving the use of living neighbours with both abiotic and biotic effects, and artificial mimics to simulate abiotic effects without biotic effects.Capitulumhad strong positive abiotic effects on the mussel survivorship in most experimental periods, while the biotic effect was negligible or weakly negative, suggesting that the net effect ofCapitulumon mussel survival was largely attributable to the abiotic effect. In contrast, a significantly negative biotic effect on the mussel growth rate was always present, though this was cancelled out by the larger, positive abiotic effect. In the case ofSeptifer, its abiotic and biotic effects on the survivorship of goose barnacles were negligible, while those on the growth rate showed temporal variation.With respect to the relationship between species interaction and environmental conditions, the strength of abiotic facilitative effect ofCapitulumon mussel survival increased with increasing abiotic stress, while the strength of biotic effect was negligible or weakly negative. As regards the effects of mussels on goose barnacles, our study indicated no obvious relationship. These results point to the importance of decomposing interaction for an accurate, mechanistic understanding of species relations and coexistence.
Climate change and the origin of migratory pathways in the Swainson's thrush,Catharus ustulatus
Authors: Ruegg Kristen C. , Hijmans Robert J. , Moritz Craig 
Published: June 2006

AbstractAim To provide a spatially explicit model of how geographic distributions at the last glacial maximum (LGM) and post‐glacial colonization routes shaped current migratory pathways in the Swainson's thrush,Catharus ustulatus, a long‐distance migratory bird.Location The Swainson's thrush breeds in boreal forest regions of the United States and Canada as well as in riparian woodlands along the Pacific coast of North America.Methods Palaeodistribution modelling is combined with mtDNA phylogeography to predict the breeding range of the Swainson's thrush at the LGM. Quantitative environmental analysis and bioclimatic modelling are used to reconstruct the most likely post‐glacial colonization pathways. A maximum likelihood method for estimating growth rates is used to approximate the relative change in population size since the LGM.Main conclusions The palaeodistribution models are concordant with the Swainson's thrush mtDNA phylogeography, suggesting that the inland and coastal groups were geographically isolated in eastern (inland) and western (coastal) regions at the LGM. Estimates of change in population size based on genetic data are remarkably consistent with estimates of change in range size, suggesting that the coastal group has undergone a 2‐ to 3‐fold demographic and range expansion, while the inland group has undergone a 6‐ to 12‐fold demographic and range expansion since the LGM. Bioclimatic analyses strongly support the hypothesis that populations expanding out of the east into previously glaciated areas in the west were undergoing a natural extension of their range by tracking the changes in climatic conditions. The combination of bioclimatic and molecular analyses is consistent with the idea that coastal and inland groups expanded from separate eastern and western regions after the LGM and that the current migratory pathway of the inland group retraces its post‐glacial colonization route.
The recent history and population structure of fiveMandarinasnail species from subtropical Ogasawara (Bonin Islands, Japan)
Authors: DAVISON ANGUS , CHIBA SATOSHI 
Published: June 2006

AbstractThe effect of Pleistocene climate change on the organisms of tropical and subtropical regions is rather poorly understood. We therefore studied the land snail genusMandarina(Bradybaenidae) of oceanic Ogasawara (Bonin Islands, Japan), with the aim of using population genetic data to understand their recent history. Our analysis of a mitochondrial 16S ribosomal RNA region from more than 600 snails in five ground‐living species suggests that populations on the small islands of Mukoujima, Anejima, Imotojima and Meijima, as well as on the low‐lying southern and central parts of Hahajima, have probably undergone recent bottlenecks followed by subsequent expansions. Except between the main island of Hahajima and Mukouijima, there is almost no evidence for gene flow among islands even though the islands were connected repeatedly by land bridges through the Pleistocene. Within islands the population structure is severe, suggestive of a long‐term, low level of gene flow (FSTis frequently greater than 0.5 among geographically close populations). Finally, there is a marked genetic patchiness, meaning that genetically close populations are sometimes separated by genetically distant populations. These patterns could be a consequence of expansion from bottlenecks, low active dispersal and founder effects caused by rare long‐distance migrants. Unfortunately, the exact nature of the refugia and bottlenecks remains unknown because the palaeoclimate of this region is poorly understood. Dating the population size changes is also challenging because the molecular clock is uncertain. We suggest, however, that arid conditions or deforestation induced by decreased atmospheric CO2may have been the main factor in determining population size.
The Aspergillus nidulans F‐box protein GrrA links SCF activity to meiosis
Authors: Krappmann Sven , Jung Nadja , Medic Branka , Busch Silke , Prade Rolf A. , Braus Gerhard H. 
Published: June 2006

SummaryCellular differentiation relies on precise and controlled means of gene expression that act on several levels to ensure a flexible and defined spatio‐temporal expression of a given gene product. In our aim to identify transcripts enriched during fruiting body formation of the homothallic ascomycete Aspergillus (Emericella) nidulans, the grrA gene could be identified in a negative subtraction hybridization screening procedure. It encodes a protein similar to fungal F‐box proteins, which function as substrate receptors for ubiquitin ligases, and that is highly related to the Saccharomyces cerevisiae regulatory protein Grr1p. Expression studies confirmed induction of grrA transcription and expression of its gene product during cleistothecial development of A. nidulans. Functional complementation of a yeast grr1Δ mutant was achieved by overexpression of the grrA coding sequence. A grrAΔ deletion mutant resembles the wild‐type in hyphal growth, asexual sporulation, Hülle cell formation or development of asci‐containing cleistothecia, but is unable to produce mature ascospores due to a block in meiosis as demonstrated by cytological staining of cleistothecial contents. Our results specify a particular involvement of the E3 ubiquitin ligase SCFGrrA in meiosis and sexual spore formation of an ascomyceteous fungus and shed light on the diverse functions of ubiquitin‐proteasome‐mediated protein degradation in eukaryotic development.
Identification of novel genomic islands coding for antigenic pilus‐like structures in Streptococcus agalactiae
Authors: Rosini Roberto , Rinaudo Cira Daniela , Soriani Marco , Lauer Peter , Mora Marirosa , Maione Domenico , Taddei Annarita , Santi Isabella , Ghezzo Claudia , Brettoni Cecilia , Buccato Scilla , Margarit Immaculada , Grandi Guido , Telford John L. 
Published: June 2006

SummaryWe have recently reported the presence of covalently linked pilus‐like structures in the human pathogen, Group B Streptococcus (GBS). The pilus operon codes for three proteins which contain the conserved amino acid motif, LPXTG, associated with cell wall‐anchored proteins together with two genes coding for sortase enzymes. Analysis of the eight sequenced genomes of GBS has led to the identification of a second, related genomic island of which there are two variants, each containing genes coding for proteins with LPXTG motifs and sortases. Here we show that both variant islands also code for pilus‐like structures. Furthermore, we provide a thorough description and characterization of the genomic organization of the islands and the role of each protein in the assembly of the pili. For each pilus, polymerization of one of the three component proteins is essential for incorporation of the other two proteins into the pilus structure. In addition, two sortases are required for complete pilus assembly, each with specificity for one of the pilus components. A component protein of one of the newly identified pili is also a previously identified protective antigen and a second component of this pilus is shown to confer protection against GBS challenge. We propose that pilus‐like structures are important virulence factors and potential vaccine candidates.
Origin inactivation in bacterial DNA replication control
Authors: Paulsson Johan , Chattoraj Dhruba K. 
Published: June 2006

SummaryInitiation of DNA replication is a highly regulated process in all organisms. Proteins that are required to recruit DNA polymerase – initiator proteins – are often used to regulate the timing or frequency of initiation in the cell cycle by limiting either their own synthesis or availability. Studies of the Escherichia coli chromosome and of bacterial plasmids with iterated initiator binding sites (iterons) have revealed that, in addition to initiator limitation, replication origin inactivation is used to prevent replication that is untimely or excessive. Our recent studies of plasmid P1 revealed that this additional mode of control becomes a requirement when initiator availability is limited only by autoregulation. Thus, although initiator limitation appears to be a well‐conserved and central mode of replication control, optimal replication might require additional control mechanisms. This review gives examples of how the multiple mechanisms can act synergistically, antagonistically or be partially redundant to guarantee low frequency events. The lessons learned are likely to help understand many other regulatory systems in the bacterial cell.
Light activates the degradation of PIL5 protein to promote seed germination through gibberellin in Arabidopsis
Authors: Oh Eunkyoo , Yamaguchi Shinjiro , Kamiya Yuji , Bae Gabyong , Chung Won‐Il , Choi Giltsu 
Published: June 2006

SummaryAngiosperm seeds integrate various environmental signals, such as water availability and light conditions, to make a proper decision to germinate. Once the optimal conditions are sensed, gibberellin (GA) is synthesized, triggering germination. Among environmental signals, light conditions are perceived by phytochromes. However, it is not well understood how phytochromes regulate GA biosynthesis. Here we investigated whether phytochromes regulate GA biosynthesis through PIL5, a phytochrome‐interacting bHLH protein, in Arabidopsis. We found that pil5 seed germination was inhibited by paclobutrazol, the ga1 mutation was epistatic to the pil5 mutation, and the inhibitory effect of PIL5 overexpression on seed germination could be rescued by exogenous GA, collectively indicating that PIL5 regulates seed germination negatively through GA. Expression analysis revealed that PIL5 repressed the expression of GA biosynthetic genes (GA3ox1 and GA3ox2), and activated the expression of a GA catabolic gene (GA2ox) in both PHYA‐ and PHYB‐dependent germination assays. Consistent with these gene‐expression patterns, the amount of bioactive GA was higher in the pil5 mutant and lower in the PIL5 overexpression line. Lastly, we showed that red and far‐red light signals trigger PIL5 protein degradation through the 26S proteasome, thus releasing the inhibition of bioactive GA biosynthesis by PIL5. Taken together, our data indicate that phytochromes promote seed germination by degrading PIL5, which leads to increased GA biosynthesis and decreased GA degradation.
Functionally redundant SHI family genes regulate Arabidopsis gynoecium development in a dose‐dependent manner
Authors: Kuusk Sandra , Sohlberg Joel J. , Magnus Eklund D. , Sundberg Eva 
Published: June 2006

SummaryGene duplication events, and the subsequent functional divergence of duplicates, are believed to be important evolutionary agents, driving morphological diversification. We have studied the structural and functional diversification of members of a plant‐specific gene family in Arabidopsis thaliana by analysing mutant phenotypes, expression patterns and phylogeny. The SHI gene family comprises ten members that encode proteins with a RING finger‐like zinc finger motif. We show that, despite being highly divergent in sequence, except in two conserved regions, many of the SHI‐related genes are partially redundant in function and synergistically promote gynoecium, stamen and leaf development in Arabidopsis. Gynoecia of the loss‐of‐function sty1‐1 mutant display subtle morphological defects, and, although mutations in the related STY2, SHI, SRS3, SRS4, SRS5, SRS7 and LRP1 genes have no apparent effect on gynoecium development, the sty1‐1 mutant phenotype is gradually enhanced in double, triple, quadruple and quintuple mutant combinations, suggesting a remarkably extensive functional conservation within the family, which appears to be based on dosage dependency and protection against dominant negative mutations. In multiple mutant lines, all marginal tissues in the apical part of the gynoecium are dramatically reduced or missing, and our data indicate that SHI family members may promote formation of these tissues downstream of the transcriptional co‐repressor LEUNIG (LUG).
Comparison of two methods for exhaled breath condensate collection
Authors: Soyer O. U. , Dizdar E. A. , Keskin O. , Lilly C. , Kalayci O. 
Published: June 2006

Background:  Exhaled breath condensate (EBC) is a noninvasive method to obtain samples from fluids lining the respiratory surfaces. Even though various methods and devices are now available, the relative efficiency of these methods for recovering airway mediators and characterizing EBC has not been established.Aim:  To compare the volume, pH, lipid mediator, and protein concentrations in EBCs collected by two commonly used commercially available devices, RTubeTM and ECoScreen.Methods:  Exhaled breath condensates were obtained consecutively using the RTubeTM and ECoScreen methods from 30 healthy, nonallergic adults. Samples were immediately placed on dry ice after collection. pH was measured after argon deaeration. Cysteinyl leukotrienes (cys‐LTs) were measured as a representative lipid mediator and eotaxin as the protein mediator by using enzyme‐linked immunosorbent assay.Results:  The mean volume of samples obtained with ECoScreen (1880 ± 116 μl) was significantly higher than that obtained with RTubeTM (1405 ± 82 μl) (P < 0.001). Concentrations of both cys‐LTs [205.4 pg/ml (65.5–472.3) with ECoScreen vs 21.6 (11.87–152.2) with RTubeTM, P < 0.001] and eotaxin [17.0 pg/ml (11.4–22.4) with ECoScreen vs 11.7 (10.5–13.5) with RTubeTM, P = 0.01] were significantly higher in samples collected with ECoScreen than with RTubeTM. There was no significant difference between the pH measurements.Conclusion:  Compared with RTubeTM, collection of exhaled breath by ECoScreen allows larger volumes to be collected and detects protein and lipid mediators with greater sensitivity. These differences in mediator recovery may be due to the differences in the collection temperature.
Meal Size Effects on Antipredator Behavior of Hatchling Trinket Snakes, Elaphe helena
Authors: Mehta Rita S. 
Published: June 2006

AbstractCurrent foraging models limit the decision‐making process of animals to the food searching and consuming phase. The post‐consummatory phase of feeding may influence optimal meal size for some species as a morphologic change often results from feeding. In snakes, a single prey item can lead to abrupt increases in body mass, thus influencing locomotor performance. Identifying factors affecting locomotor performance can help predict behaviors that should maximize an animal's chance of evading predators. Although many snakes ingest large percentages of their body mass, not much work has examined the post‐consummatory effects of ingesting bulky prey differing in relative mass. I examined the locomotor performance and antipredator tactics of hatchling trinket snakes (Elaphe helena) after subjecting snakes to mice prey varying by relative mass differences of 20–35%, 50–59% or 70–79% of an individual hatchling's body mass. Snakes in treatment groups were compared with snakes in a control group (0%). Meal size‐affected locomotor parameters such as burst speed, endurance, and endurance times for hatchlings that ingested 50–59% and 70–79% of their body mass (p < 0.001). Recent feeding also affected the types of antipredator modes employed. Hatchlings in the 0% and 20–35% treatments exhibited behaviors that were categorized as active and threatening, while hatchlings in the 50–59% and 70–79% treatments exhibited stationary, neutral, and cryptic behaviors. Although snakes may become more reclusive following a meal, this study demonstrates that relative prey mass affects the ability of hatchling trinket snakes to flee from a predator. In turn, these results suggest that the post‐consummatory effects of foraging should be considered in optimal foraging models for organisms that consume a substantial portion of their body mass during a single feeding.
RESEARCH AND DEVELOPMENT IN SMALL AND MEDIUM‐SIZED ENTERPRISES: THE ROLE OF FINANCIAL CONSTRAINTS AND PUBLIC FUNDING
Authors: Czarnitzki Dirk 
Published: June 2006

ABSTRACTThis paper presents microeconometric evidence on financing constraints for research and development activities in German small‐ and medium‐sized firms (SME). Special attention is paid to the role of public research and development (R&D) subsidies. For this purpose SMEs in West and East Germany are compared because these regions are very different in their supply of public R&D funding. The empirical evidence suggests that West German SMEs are financially constrained in their R&D activities by both internal and external resources. In East Germany, firms are not sensitive to external constraints, possibly due to high public R&D subsidies. The results show that R&D in East Germany is to a large extent driven by public subsidies and that the usual financial market mechanisms are dysfunctional with respect to R&D in this region.
ARTHUR SELDON: GREAT EDITOR, THINKER AND RADICAL ECONOMIST
Authors: Harris Ralph , Waterhouse Stuart , Anderson Martin , Howe Geoffrey 
Published: June 2006

Editor's note Arthur Seldon, the founder editor of Economic Affairs and first Editorial Director of the IEA, died in October 2005, a few weeks before the 25th anniversary issue went to press. Many tributes have been paid to Arthur Seldon in obituaries in The Economist and the major national newspapers. In this special section of Economic Affairs we reproduce four of the speeches given at his memorial service on 15 January 2006. Respectively, they illustrate the fond affection for Arthur Seldon felt by Ralph Harris, the founder General Director of the IEA; Stuart Waterhouse, a fellow LSE student; Martin Anderson, who worked with Arthur Seldon editing Economic Affairs; and Geoffrey Howe, former Chancellor of the Exchequer. Three members of Arthur Seldon's family also spoke at the memorial service. Their talks concentrated on Arthur Seldon's family life, but the following more general thoughts particularly resonated with all present. His adopted son, Michael Perrott, commented that he was ‘a lion amongst thinkers, timeless and uncompromising’. Peter Seldon spoke of his father as ‘a visionary’ and ‘a genius’; he concluded, ‘we are all unique but the word could have been invented for Arthur’. Peter's brother Anthony Seldon commented that ‘he [Arthur] lives on in all of us’. – Philip Booth
Mechanical disruption of seagrass in the digestive tract of the dugong
Authors: Lanyon J. M. , Sanson G. D. 
Published: June 2006

AbstractThe cheek teeth in dugongs are considered to be largely non‐functional whereas the oral horny pads are important both in mechanical disruption of the diet and in conveying seagrass through the mouth. Particle size distributions of digesta from 41 dead stranded dugongs were examined to investigate the relationship between degree of food breakdown, gut region and functional surface area of the mouthparts. The in vitro ease of fracture of major dietary seagrass species were compared. The rate of food breakdown through the gut appears to be more closely linked to fibre level of the diet than to size or age of the dugong and its mouthparts. Low fibre seagrass, for example Halophila ovalis, breaks down at a faster rate than high fibre seagrass, for example Zostera capricorni both in dugong guts and in vitro. Several structural characteristics of seagrass, including level and arrangement of fibre, and water content, make it particularly amenable to mechanical breakdown. The soft mouthparts of the dugong are highly modified so that the entire oral cavity functions to crush low fibre seagrasses. Thus, the dugong has developed an efficient method of food ingestion and mastication that is suited to processing large quantities of soft seagrass during short dive times. The potential cost to the dugong in having lost its hard dental surfaces is that it has become restricted to a low fibre diet.