bluuebunny/crossref_metadata_2025 huggingface dataset:
A resistance-like gene identified by EST mapping and its association with a QTL controllingFusariumhead blight infection on wheat chromosome 3BS
Authors: Shen Xiaorong , Francki Michael G , Ohm Herbert W
Published: August 2006

Fusarium head blight (FHB) is a major disease in the wheat growing regions of the world. A quantitative trait locus (QTL) on the short arm of chromosome 3B controls much of the variation for resistance. The cloning of candidate disease-resistance genes for FHB QTLs on chromosome 3B can provide further elucidation of the mechanisms that control resistance. However, rearrangements and divergence during plant genome evolution often hampers the identification of sequences with similarity to known disease-resistance genes. This study focuses on the use of wheat expressed sequence tags (ESTs) that map to the region on chromosome 3B containing the QTL for FHB resistance and low-stringency BLAST searching to identify sequences with similarity to known disease-resistance genes. One EST rich with leucine repeats and low similarity to a protein kinase domain of the barley Rpg1 gene was identified. Genetic mapping using a Ning894037 × Alondra recombinant inbred (RI) population showed that this EST mapped to the QTL on the short arm of chromosome 3B and may represent a portion of a newly diverged gene contributing to FHB resistance. The EST is a new marker suitable for marker-assisted selection and provides a starting point to begin map-based cloning for chromosome walking and investigate new diverged genes at this locus.Key words: Fusarium head blight resistance, expressed sequence tags, quantitative trait loci, Rpg1, wheat.
Origin and evolution of Andigena potatoes revealed by chloroplast and nuclear DNA markers
Authors: Sukhotu Thitaporn , Hosaka Kazuyoshi
Published: August 2006

Andigena potatoes (Solanum tuberosum L. subsp. andigena Hawkes) (2n = 4x = 48) are important, native-farmer-selected cultivars in the Andes, which form a primary gene pool for improving a worldwide grown potato (S. tuberosum subsp. tuberosum). To elucidate the origin of Andigena, 196 Andigena accessions were compared with 301 accessions of 33 closely related cultivated and wild species using several types of chloroplast DNA (ctDNA) markers and nuclear DNA (nDNA) restriction fragment length polymorphism (RFLP) markers. Fourteen ctDNA types (haplotypes) and 115 RFLP bands were detected in Andigena, of which the main haplotypes and frequent RFLP bands were mostly shared with a cultivated diploid species, S. stenotomum Juz. et Buk. Principal component analysis of nDNA polymorphisms revealed a progressive and continuous variation from Peruvian wild species with C-type ctDNA to a group of wild species having S-type ctDNA in its variation range (S. bukasovii, S. canasense, S. candolleanum, and S. multidissectum), to cultivated diploid potatoes (S. phureja and S. stenotomum), and to cultivated tetraploid potatoes (Andigena and Chilean S. tuberosum subsp. tuberosum). These results suggest that the initial Andigena population arose with multiple origins exclusively from S. stenotomum. The overall evolutionary process toward the present-day Andigena was discussed.Key words: Andigena, chloroplast DNA, nuclear DNA RFLPs, origin, sexual tetraploidization.
Genetic diversity of Crotalaria germplasm assessed through phylogenetic analysis of EST-SSR markers
Authors: Wang M L , Mosjidis J A , Morris J B , Dean R E , Jenkins T M , Pederson G A
Published: August 2006

The genetic diversity of the genus Crotalaria is unknown even though many species in this genus are economically valuable. We report the first study in which polymorphic expressed sequence tag-simple sequence repeat (EST-SSR) markers derived from Medicago and soybean were used to assess the genetic diversity of the Crotalaria germplasm collection. This collection consisted of 26 accessions representing 4 morphologically characterized species. Phylogenetic analysis partitioned accessions into 4 main groups generally along species lines and revealed that 2 accessions were incorrectly identified as Crotalaria juncea and Crotalaria spectabilis instead of Crotalaria retusa. Morphological re-examination confirmed that these 2 accessions were misclassified during curation or conservation and were indeed C. retusa. Some amplicons from Crotalaria were sequenced and their sequences showed a high similarity (89% sequence identity) to Medicago truncatula from which the EST-SSR primers were designed; however, the SSRs were completely deleted in Crotalaria. Highly distinguishing markers or more sequences are required to further classify accessions within C. juncea.Key words: Crotalaria germplasm, EST-SSR, genetic diversity, phylogeny.
Dynamic analysis of rectangular liquid containers in three-dimensional space
Authors: Kianoush M R , Mirzabozorg H , Ghaemian M
Published: August 2006

A new method for seismic analysis of containers in three-dimensional space is introduced in which the effects of both impulsive and convective components and their corresponding damping are accounted for in time domain. A case study is performed to investigate the behaviour of a concrete rectangular container under the effects of horizontal and vertical ground motions using the scaled earthquake components of the 1940 El-Centro earthquake record. Two-dimensional behaviour of the tank is assumed. The results of the study are compared with those obtained using the current practice and those determined from finite element (FE) analysis based on a lumped mass model. The results of the FE analysis with the equivalent added masses and rigid walls are in good agreement with those from the current practice. Compared with the proposed method, however, the current practice overestimates the response of the container. Also, the vertical excitation leads to a significant response in the container, but combining the effects of horizontal and vertical excitations reduces the response of the structure in the considered system.Key words: liquid, rectangular container, sloshing, staggered method, three-dimensional space, vertical excitation.
Oral administration of lactoferrin increases hemoglobin and total serum iron in pregnant womenThis paper is one of a selection of papers published in this Special Issue, entitled 7th International Conference on Lactoferrin: Structure, Function, and Applications, and has undergone the Journal's usual peer review process.
Authors: Paesano Rosalba , Torcia Francesco , Berlutti Francesca , Pacifici Enrica , Ebano Valeria , Moscarini Massimo , Valenti Piera
Published: August 2006

Iron deficiency anemia (IDA) during pregnancy continues to be of world-wide concern. IDA is a risk factor for preterm delivery and subsequent low birth weight, and possibly for poor neonatal health. Iron supplementation in pregnancy is a widely recommended practice, yet intervention programs have met with many controversies. In our study, 300 women at different trimesters of pregnancy were enrolled in a trial of oral administration of ferrous sulfate (520 mg once a day) or 30% iron-saturated bovine lactoferrin (bLf) (100 mg twice a day). Pregnant women refusing treatment represented the control group. In this group hemoglobin and total serum iron values measured after 30 d without treatment decreased significantly, especially in women at 18–31 weeks of pregnancy. In contrast, after 30 d of oral administration of bLf, hemoglobin and total serum iron values increased and to a greater extent than those observed in women treated orally for 30 d with ferrous sulfate, independently of the trimester of pregnancy. Unlike ferrous sulfate, bLf did not result in any side effects. These findings lead us to hypothesize that lactoferrin could influence iron homeostasis directly or through other proteins involved in iron transport out of the intestinal cells into the blood.
Human lactoferrin controls the level of retinoblastoma protein and its activityThis paper is one of a selection of papers published in this Special Issue, entitled 7th International Conference on Lactoferrin: Structure, Function, and Applications, and has undergone the Journal's usual peer review process.
Authors: Son Hee-Joung , Lee Shin-Hee , Choi Sang-Yun
Published: August 2006

Lactoferrin (Lf) has been implicated in the regulation of cell growth. However, the molecular mechanism underlying this effect remains to be elucidated. In this study, we show that Lf is involved in the cell cycle control system in a variety of cell lines, through retinoblastoma protein (Rb) - mediated growth arrest. We observed that Lf induces the expression of Rb, a signal mediator of cell cycle control, and that a majority of this Lf-induced Rb persists in a hypophosphorylated form. In addition, we determined that Lf specifically augments the level of a cyclin-dependent kinase inhibitor, p21, but not p27. Upon treatment with Lf, H1299 cells expressing defective p53 effected an augmentation of endogenous p21 levels, which may contribute to the accumulation of hypophosphorylated Rb. A substantial quantity of active Rb binds more efficiently to E2F1 in cells that express Lf and consequently blocks the expression of an E2F1-responsive gene, thereby suggesting that Lf plays a crucial role in the inhibition of tumor cell growth. Therefore, we conclude that the antiproliferative effects of Lf can likely be attributed to the elevated levels of hypophosphorylated Rb.
Transformation of Metarhizium anisopliae mediated by Agrobacterium tumefaciens
Authors: Fang Weiguo , Pei Yan , Bidochka Michael J
Published: August 2006

A simple, highly efficient, and reliable Agrobacterium tumefaciens-mediated transformation method was developed for the insect pathogenic fungus Metarhizium anisopliae. Expression of the green fluorescent protein gene, egfp, and the benomyl resistance gene, benA3, were used as markers in transformed M. anisopliae. Transformation efficiencies were dependent on the strain of A. tumefaciens used. With strain AGL-1, 17.0 ± 1.4 transformants per plate could be obtained using conidial concentrations of 106 conidia/mL and a 2 day co-cultivation in the presence of 200 µmol/L acetosyringone. On the other hand, transformations using strain LBA4404 were unsuccessful. Ten transformants were tested by Southern analysis and found to contain a single copy T-DNA. Twenty transformants were subcultured for five generations on nonselective media, and 95% of the transformants were mitotically stable. Agrobacterium tumefaciens-mediated transformation of M. anisopliae can serve as a useful tool to investigate genes involved in insect pathogenicity.Key words: entomopathogenic fungi, Metarhizium anisopliae, Agrobacterium tumefaciens, genetic transformation.
Seasonal influences on fungal community structure in unimproved and improved upland grassland soils
Authors: Kennedy Nabla , Brodie Eoin , Connolly John , Clipson Nicholas
Published: August 2006

Seasonal and management influences on the fungal community structure of two upland grassland soils were investigated. An upland site containing both unimproved floristically diverse (U4a) and improved mesotrophic (MG7b) grassland types was selected. Samples from both grassland types were taken at five times in one year. Soil fungal community structure was assessed using fungal automated ribosomal intergenic spacer analysis (ARISA), a DNA-profiling approach. A grassland management regime was found to strongly affect fungal community structure, with fungal ARISA profiles from unimproved and improved grassland soils differing significantly. The number of fungal ribotypes found was higher in unimproved than improved grassland soils, providing evidence that improvement may reduce the suitability of upland soil as a habitat for specific groups of fungi. Seasonal influences on fungal community structure were also noted, with samples taken in autumn (October) more correlated with change in ribotype profiles than samples from other seasons. However, seasonal variation did not obscure the measurement of differences in the fungal community structure that were due to agricultural improvement, with canonical correspondence analysis indicating grassland type had a stronger influence on fungal profiles than did season.Key words: upland grasslands, fungal automated ribosomal intergenic spacer analysis, seasonality, improvement, canonical correspondence analysis.
Vacuolar localization of phosphorus in hyphae ofPhialocephala fortinii, a dark septate fungal root endophyte
Authors: Saito Katsuharu , Kuga-Uetake Yukari , Saito Masanori , Peterson R. Larry
Published: August 2006

Phialocephala fortinii is a dark septate fungal endophyte that colonizes roots of many host species. Its effect on plant growth varies from being pathogenic to beneficial. The basic biology of this species has received little research, and thus the main objectives of this study were to determine cytological features of hyphae, including the nature of the vacuolar system, and whether polyphosphate was present in vacuoles. Both living hyphae and hyphae that had been rapidly frozen and freeze substituted before embedding were studied. A complex system of vacuoles, including a motile tubular vacuolar system, elongated vacuoles, and spherical vacuoles, was demonstrated in living hyphae by the fluorescent probe Oregon Green 488 carboxylic acid diacetate, using laser scanning confocal microscopy. The motile tubular vacuolar system was more prevalent at the hyphal tip than in more distal regions, whereas elongated vacuoles and spherical vacuoles were more abundant distal to the tip. All vacuoles contained polyphosphate as shown by labelling embedded samples with recombinant polyphosphate binding domain of Escherichia coli exopolyphosphatase, containing Xpress tag at the N-terminal end, followed by anti-Xpress antibody and a secondary antibody conjugated either to a fluorescent probe for laser scanning confocal microscopy or colloidal gold for transmission electron microscopy. The polyphosphate was dispersed in vacuoles. This was confirmed by staining embedded samples with 4′,6-diamidino-2-phenylindole and viewing with UV light using epifluorescence microscopy. These cytological methods showed that the tubular vacuolar system had lower concentrations of polyphosphate than the spherical vacuoles. Lipid bodies were present around vacuoles.Key words: Phialocephala, motile tubular vacuoles, vacuoles, polyphosphate, lipid.
Role of phyllosphere fungi of forest trees in the development of decomposer fungal communities and decomposition processes of leaf litter
Authors: Osono T
Published: August 2006

The ecology of endophytic and epiphytic phyllosphere fungi of forest trees is reviewed with special emphasis on the development of decomposer fungal communities and decomposition processes of leaf litter. A total of 41 genera of phyllosphere fungi have been reported to occur on leaf litter of tree species in 19 genera. The relative proportion of phyllosphere fungi in decomposer fungal communities ranges from 2% to 100%. Phyllosphere fungi generally disappear in the early stages of decomposition, although a few species persist until the late stages. Phyllosphere fungi have the ability to utilize various organic compounds as carbon sources, and the marked decomposing ability is associated with ligninolytic activity. The role of phyllosphere fungi in the decomposition of soluble components during the early stages is relatively small in spite of their frequent occurrence. Recently, the roles of phyllosphere fungi in the decomposition of structural components have been documented with reference to lignin and cellulose decomposition, nutrient dynamics, and accumulation and decomposition of soil organic matter. It is clear from this review that several of the common phyllosphere fungi of forest trees are primarily saprobic, being specifically adapted to colonize and utilize dead host tissue, and that some phyllosphere fungi with marked abilities to decompose litter components play important roles in decomposition of structural components, nutrient dynamics, and soil organic matter accumulation.Key words: carbon cycle, community, endophyte, epiphyte, succession.
myo-Inositol phosphate isomers generated by the action of a phytate-degrading enzyme from Klebsiella terrigena on phytate
Authors: Greiner Ralf , Carlsson Nils-Gunnar
Published: August 2006

For the first time a dual pathway for dephosphorylation of myo-inositol hexakisphosphate by a histidine acid phytase was established. The phytate-degrading enzyme of Klebsiella terrigena degrades myo-inositol hexakisphosphate by stepwise dephosphorylation, preferably via D-Ins(1,2,4,5,6)P5, D-Ins(1,2,5,6)P4, D-Ins(1,2,6)P3, D-Ins(1,2)P2 and alternatively via D-Ins(1,2,4,5,6)P5, Ins(2,4,5,6)P4, D-Ins(2,4,5)P3, D-Ins(2,4)P2 to finally Ins(2)P. It was estimated that more than 98% of phytate hydrolysis occurs via D-Ins(1,2,4,5,6)P5. Therefore, the phytate-degrading enzyme from K. terrigena has to be considered a 3-phytase (EC 3.1.3.8). A second dual pathway of minor importance could be proposed that is in accordance with the results obtained by analysis of the dephosphorylation products formed by the action of the phytate-degrading enzyme of K. terrigena on myo-inositol hexakisphosphate. It proceeds preferably via D-Ins(1,2,3,5,6)P5, D-Ins(1,2,3,6)P4, Ins(1,2,3)P3, D-Ins(2,3)P2 and alternatively via D-Ins(1,2,3,5,6)P5, D-Ins(2,3,5,6)P4, D-Ins(2,3,5)P3, D-Ins(2,3)P2 to finally Ins(2)P. D-Ins(2,3,5,6)P4, D-Ins(2,3,5)P3, and D-Ins(2,4)P2 were reported for the first time as intermediates of enzymatic phytate dephosphorylation. A role of the phytate-degrading enzyme from K. terrigena in phytate breakdown could not be ruled out. Because of its cytoplasmatic localization and the suggestions for substrate recognition, D-Ins(1,3,4,5,6)P5 might be the natural substrate of this enzyme and, therefore, may play a role in microbial pathogenesis or cellular myo-inositol phosphate metabolism.Key words: myo-inositol phosphate isomers, phytate-degrading enzyme, phytate, phytase, Klebsiella terrigena.
Characterization and genetic variability ofFusarium verticillioidesstrains isolated from corn and sorghum in Brazil based on fumonisins production, microsatellites, mating type locus, and mating crosses
Authors: da Silva Valéria Nascimento , Fernandes Flora Maria Campos , Cortez Adriana , Ribeiro Deise Helena Baggio , de Almeida Adriana Palma , Hassegawa Regina Hiroko , Corrêa Benedito
Published: August 2006

Fusarium verticillioides (Gibberella fujikuroi mating population A) is a producer of fumonisins and one of the main contaminants of corn grains. In Brazil, some studies analyzing strains isolated from corn have demonstrated high levels of fumonisins, whereas the levels for strains isolated from sorghum have been found to be low. In the present study, we investigated the genetic diversity of 22 F. verticillioides strains isolated from corn and 21 strains isolated from sorghum cultivated in the State of São Paulo, Brazil. Differences in the genetic profile were observed between the strains isolated from the two substrates using single primer amplification reaction by polymerase chain reaction (SPAR-PCR). Fumonisins levels were higher in strains isolated from corn than in those isolated from sorghum. The MAT-1 and MAT-2 alleles were identified by PCR, and the isolates were subsequently crossed with Fusarium thapsinum (G. fujikuroi mating population F) reference strains because this species is morphologically similar to F. verticillioides and produces low levels of fumonisins. The SPAR haplotypes of some strains isolated from sorghum were similar to the F. thapsinum reference strain haplotypes, but there was no fertile mating between the strains isolated from the two substrates and the F. thapsinum references strains. The MAT-1:MAT-2 proportion was 5:17 and 14:7 for isolates from corn and sorghum, respectively.Key words: Fusarium verticillioides, fumonisins, single primer amplification reaction, mating types.
Fluorescence spectroscopy: a rapid tool for assessing tetracycline resistance in Bifidobacterium longum
Authors: Ammor Mohammed Salim , Flórez Ana Belén , Margolles Abelardo , Mayo Baltasar
Published: August 2006

The tetracycline uptake kinetics of 35 Bifidobacterium longum strains isolated from the human gastrointestinal tract were examined by fluorescence spectroscopy, and the suitability of the technique as a screening tool of tetracycline resistance or susceptibility was determined. The strains were first grouped into three classes based on their corresponding minimum inhibitory concentrations (MICs) of tetracycline, as established by the microdilution method: susceptible (MICs ≤1 µg mL–1), semi-resistant (MICs between 1 and ≤32 µg mL–1), and resistant strains (MICs ≥32 µg mL–1). The kinetics of tetracycline uptake for the strains in each resistance group were then analyzed over a 20 min period by fluorescence spectroscopy (absorbance wavelength 524 nm, excitation wavelength 400 nm) in a buffer system containing 100 µg mL–1 tetracycline. Principal component analysis and factorial discriminant analysis of the results showed excellent distinction among susceptible, semi-resistant, and resistant strains. The proposed method provides a powerful and convenient means of rapidly screening tetracycline resistance in B. longum.Key words: fluorescence spectroscopy, Bifidobacterium longum, antibiotic resistance, tetracycline uptake, multidimensional data analysis.
Organic acids production by white rot Basidiomycetes in the presence of metallic oxides
Authors: Jarosz-Wilkołazka Anna , Grąz Marcin
Published: August 2006

The purpose of the present work was to determine if selected fungal strains belonging to wood-rotting Basidiomycetes are able to grow on and to solubilize different insoluble oxides in solid media. Twenty-eight strains of white rot fungi were checked for their growth on oxide-amended media (ZnO, CaO, Cu2O). All strains displayed growth on Zn-amended plates but to a different extent, and Cu2O-amended plates turned out to be the most toxic oxide. Most of the tested strains solubilized oxalates and produced noticeable clear zones under the mycelium. These clear zones were tested for the presence of organic acids, the level of which was clearly elevated upon exposure of fungal strains to insoluble oxides. We determined the presence of oxalic, malic, and formic acids, with oxalic acid the predominant one.Key words: metal oxalates, oxalic acid, insoluble oxides, wood-rotting fungi.
Environmental stochasticity: empirical estimates of prairie vole survival with implications for demographic models
Authors: Reed Aaron W. , Slade Norman A.
Published: August 2006

A rich theory exists regarding the potential impact of correlations among vital rates on population projections derived from demographic models. However, relatively little is known about the magnitude of correlations among vital rates in natural populations, particularly in mammals. We used 30 years of mark–recapture data from a population of prairie voles ( Microtus ochrogaster (Wagner, 1842)) to test for differences in survival among mass classes and sexes, in correlations among vital rates, in correlations between vital rates and environmental factors, and in autocorrelation in vital rates. Estimated monthly survival rates did not differ significantly among mass classes and there were no significant cross-correlations among mass classes. Survival of large prairie voles increased in mild winters (i.e., warm temperatures and low snowfall). Survival rates of medium and large voles were negatively autocorrelated at time lags of 9–12 months, and survivals of large voles were positively autocorrelated for time lags of <3 months. These autocorrelations were not explained by patterns of temperature or precipitation. The observed degree of autocorrelation in vital rates is sufficient to affect projections from demographic models, particularly in short-lived taxa that require seasonal or monthly estimation of vital rates.
Oviposition-site selection by the toad Melanophryniscus rubriventris in an unpredictable environment in Argentina
Authors: Goldberg F.J. , Quinzio S. , Vaira M.
Published: August 2006

Oviposition-site selection plays an important role in the reproductive success of amphibians. In unpredictable environments where resources vary within a season, amphibians should select oviposition sites using parameters that can be easily evaluated, or spawn in several ponds to increase offspring survival. Melanophryniscus rubriventris (Vellard, 1947) uses shallow ephemeral ponds in an unpredictable montane-forest environment. During 40 consecutive days, we surveyed potential spawning sites and measured several biotic and abiotic factors to determine if any of these factors influenced breeding-site selection. We also described the spawning behavior of this species. Water temperature and pond level (flooded or not) were significant predictors of whether a pond was used or not. Warmer ponds would permit accelerated development of larvae in habitats where ponds are ephemeral and their presence unpredictable. Because of the short and unpredictable hydroperiods, it will be better to select a pond full of water instead of evaluating other pond characteristics that can be very variable. Mating pairs spread several egg masses to different sites but in the same pond. This behavior is likely a consequence of pairs avoiding interactions with intruding males and not as a strategy to enhance offspring survival.
Winter huddling groups in the striped mouse
Authors: Schradin C. , Schubert M. , Pillay N.
Published: August 2006

Huddling is a strategy to avoid heat loss and thus save energy and is often observed in birds and rodents, which, because of their small body size, are prone to relatively high heat loss. Huddling might thus explain group-living in some cases, such as the winter huddling groups described for several northern hemisphere rodents. Here we describe winter huddling groups in an African rodent, the striped mouse ( Rhabdomys pumilio (Sparrman, 1784)), from the Succulent Karoo of South Africa. Striped mice were radio-tracked and observed directly in the field. The importance of huddling in this species was demonstrated by comparing data collected over 2 years. The 2003 winter was characterized by a severe drought and 99% mortality. As a result, close kin were mainly unavailable and striped mice slept in non-kin huddling groups. In 2004, normal winter rainfall occurred, mortality was only 50%, and striped mice formed family groups that shared a nest at night. While family groups were stable in 2004, non-kin huddling groups in 2003 were highly flexible and often changed from night to night. Huddling groups are important for striped mice to save energy, and the instability of non-kin sleeping groups indicates that the potential for conflict is higher between non-kin than between kin and that there is a trade-off between thermoregulatory requirements and kin selection.
Correlated cycles of snowshoe hares and Dall’s sheep lambs
Authors: Wilmshurst J.F. , Greer R. , Henry J.D.
Published: August 2006

We tested the hypothesis that the number of surviving lambs counted in mid-summer from a Dall’s sheep ( Ovis dalli Nelson, 1884) population on Sheep Mountain, Yukon, Canada, is correlated to the density of snowshoe hares ( Lepus americanus Erxleben, 1777) in the surrounding boreal forest. We examined correlations between the number of lambs and the number of snowshoe hares at different phases in the 10-year snowshoe hare cycle. There were significant cross-correlations between the ratio of lambs to nursery sheep and hare densities with 1- and 2-year time lags. Lamb numbers also showed clockwise rotation with respect to hare densities when points were joined chronologically. Simple population models suggest several relationships: when hare densities are high, lamb population growth rates are inversely related to hare densities; during the low phase of the hare population cycle, lamb population growth rates show density-independent fluctuations. In the absence of compelling evidence for direct interactions between Dall’s sheep and hares, we hypothesize that the inverse relationship between lamb population growth and hare density is mediated indirectly by shared predators.
A comparison of parasite loads on asexual and sexual Phoxinus (Pisces: Cyprinidae)
Authors: Mee J.A. , Rowe L.
Published: August 2006

In light of the inherent disadvantages of sexual reproduction, the existence of sex is often seen as a paradox. There are a variety of hypothetical benefits of sexual reproduction that may balance its disadvantages. The Red Queen hypothesis proposes that sexually reproducing species are better able to evolve resistance to parasites than asexually reproducing species. A prediction of the Red Queen hypothesis is that a parasite should evolve to preferentially exploit an asexual species over a sexual species. To test this central prediction of the Red Queen hypothesis, intensity of infection by the parasite Gyrodactylus eos Mayes, 1977 (Monogenea) was compared between sympatric asexual and sexual fish species in the genus Phoxinus Rafinesque, 1820. In each lake where these species coexist, the asexual fish should suffer higher intensities of infection than the sexual fish. In the majority of lakes sampled, there were more parasites on asexual than sexual fish.
Sexual dimorphism in pelvic fin length of Atlantic cod
Authors: Skjæraasen Jon Egil , Rowe Sherrylynn , Hutchings Jeffrey A.
Published: August 2006

Behavioural differences between females and males may result in sexual dimorphism among morphological traits associated with these behaviours. In the broadcast-spawning Atlantic cod ( Gadus morhua L., 1758), release of gametes occurs during a “ventral mount” in which the male positions himself directly beneath the female while grasping her with his pelvic fins. Males also display the pelvic fins during agonistic encounters with other males. Based on data obtained from four Atlantic cod populations off Canada and Norway, we find clear evidence of sexual dimorphism in pelvic fin size, the fins being significantly larger in males than in females. Pelvic fin size was, however, not more variable than other morphological traits and was not correlated with body condition or drumming muscles mass (hypothesized to be a secondary sexual characteristic in this species). To our knowledge, this is the first study to demonstrate sexual dimorphism in any external morphological trait in a gadoid fish. Although the observed differences in pelvic fin size may be a product of sexual selection, we identify future work to test this hypothesis and to explore more fully the causes and fitness consequences of this sexual bias in Atlantic cod.
THREE-DIMENSIONAL APOLLONIAN NETWORKS
Authors: SOARES DANYEL J. B. , ANDRADE JOSÉ S. , HERRMANN HANS J. , da SILVA LUCIANO R.
Published: August 2006

We discuss the three-dimensional Apollonian network introduced by Andrade et al.1 for the two-dimensional case. These networks are simultaneously scale-free, small world, Euclidean, space-filling and matching graphs and have a wide range of applications going from the description of force chains in polydisperse granular packings to the geometry of fully fragmented porous media. Some of the properties of these networks, namely, the connectivity exponent, the clustering coefficient, the shortest path, and vertex betweenness are calculated and found to be particularly rich.
PERCOLATION ON GROWING LATTICES
Authors: TIGGEMANN DANIEL
Published: August 2006

In order to investigate the dependence on lattice size of several observables in percolation, the Hoshen–Kopelman algorithm was modified so that growing lattices could be simulated. By this way, when simulating a lattice of size L, lattices of smaller sizes can be simulated in the same run for free, saving computing time.

Here, site percolation in three dimensions was studied. Lattices of up to L = 5000, with many L-steps in between, have been simulated, for occupation probabilities of p = 0.25, p = 0.3, p = pc = 0.311608, and p = 0.35.
THERMAL LATTICE BOLTZMANN MODEL WITH VISCOUS HEAT DISSIPATION IN THE INCOMPRESSIBLE LIMIT
Authors: TIAN ZHI-WEI , ZOU CHUN , LIU H. J. , LIU Z. H. , GUO Z. L. , ZHENG C. G.
Published: August 2006

A novel thermal lattice Boltzmann (LB) model is proposed to obtain the viscous heat term expediently. Unlike the existing thermal LB models, this model is entirely based on the framework of the LB method and directly derived from the macro temperature equation. Moreover, the computation cost decreases because the computation of complicated material derivative term has been avoided successfully. To testify the simulation capability of this model, the thermal Couette flow is simulated and the results indicate agreement with the analytical solutions.
NUMERICAL EFFECTS IN A FINITE DIFFERENCE LATTICE BOLTZMANN MODEL FOR LIQUID-VAPOUR SYSTEMS
Authors: CRISTEA ARTUR
Published: August 2006

A two-dimensional finite difference Lattice Boltzmann model for liquid-vapour systems is introduced. Phase separation is achieved using the dimensionless van der Waals equation of state. A force term is added to account for the surface tension. Flux limiters and TVD schemes are used to improve the accuracy of this model.
IDENTIFYING AND DATING THE EPISODES OF SPECULATIVE PRESSURES AGAINST THE SINGAPORE DOLLAR
Authors: PONTINES VICTOR , SIREGAR REZA
Published: August 2006

The key objective of this study is to bring into light several shortcomings of early literatures in identifying episodes of currency crises. A careful examination of the basic statistical distribution of exchange market pressure index, based on a weighting scheme proposed by Eichengreen–Rose–Wyplosz (1995, 1996), reveals that the conventional method of defining currency crisis is statistically flawed. This study applies an alternative statistical method known as Extreme Value Analysis (EVA), originally developed by Hill (1975), and, more recently, extended by Huisman et al. (2001) to the case of Singapore from 1985 to 2003.
ATOMIC DIPOLE SQUEEZING IN THE DEGENERATE Λ QUANTUM BEAT THREE-LEVEL SYSTEM
Authors: ZHOU QING-CHUN , ZHU SHI NING
Published: August 2006

By using the full quantum theory, we investigate the time evolution of the atomic dipole squeezing parameters of a Λ-type three-level atom interacting with a single-mode coherent optical field, and study the influence of the initial coherent-field intensity, the initial atomic coherence, the initial populations and energy splitting of the two lower atomic levels on the atomic dipole squeezing. The influence of a classical external driving field coupling to the atom on the atomic dipole squeezing is also explored at the end of the paper.
DECOHERENCE IN COMPOSITE QUANTUM OPEN SYSTEMS: THE EFFECTIVENESS OF UNSTABLE DEGREES OF FREEDOM
Authors: LOMBARDO FERNANDO C. , VILLAR PAULA I.
Published: August 2006

The effect induced by an environment on a composite quantum system is studied. The model considers the composite system as comprised by a subsystem A coupled to a subsystem B which is also coupled to an external environment. We studied all possible four combinations of subsystems A and B made up with a harmonic oscillator and an upside down oscillator. We analyzed the decoherence suffered by subsystem A due to an effective environment composed by subsystem B and the external reservoir. In all the cases we found that subsystem A decoheres even though it interacts with the environment only through its sole coupling to B. However, the effectiveness of the diffusion depends on the unstable nature of subsystem A and B. Therefore, the role of this degree of freedom in the effective environment is analyzed in detail.
Widespread arc-related melting in the mantle section of the northern Oman ophiolite as inferred from detrital chromian spinels
Authors: Arai S. , Kadoshima K. , Morishita T.
Published: August 2006

We examined detrital chromian spinels, in recent river beds, derived from the mantle section to deterrmine whether the mantle peridotite of the northern Oman ophiolite is of oceanic or arc origin. The Cr-number (= Cr/(Cr + Al) atomic ratio) of the detrital chromian spinels mostly ranges from 0.4 to 0.8, and more than 60% of them have Cr-numbers higher than 0.6. This indicates a significant extent of island-arc nature because chromian spinels seldom have Cr-numbers higher than 0.6 in ocean-floor rocks. The high-Cr-number (>0.6) spinels, which are also low in TiO
2
(<0.3 wt%), are probably derived from an arc setting. Lherzolite with spinel Cr-numbers <0.2 is absent except near the base of the section. The high-Cr-number detrital chromian spinels are more abundant from the mantle section with more frequent discordant dunite pods. Post-deformational discordant dunite and adjacent harzburgite include the high-Cr-number spinels in outcrops. The upper mantle of the northern Oman ophiolite was formed at a fast-spreading ridge and was later modified by island-arc magmatism in a subduction-zone environment. This switch of tectonic setting from a mid-oceanic ridge to an island arc is essential in the explanation of obduction of a slice of oceanic lithosphere onto a continental margin as an ophiolite.
U–Pb age constraints on Variscan magmatism and Ni–Cu–PGE metallogeny in the Ossa–Morena Zone (SW Iberia)
Authors: Romeo I. , Lunar R. , Capote R. , Quesada C. , Dunning G.R. , Piña R. , Ortega L.
Published: August 2006

New U–Pb zircon ages from the Santa Olalla Igneous Complex have been obtained, which improve the knowledge of the precise timing of Variscan magmatism in the Ossa–Morena Zone, SW Iberia. This complex has a special relevance as it hosts the most important Ni–Cu–platinum group element (PGE) mineralization in Europe: the Aguablanca deposit. U–Pb zircon ages have been obtained for seven samples belonging to the Santa Olalla Igneous Complex and spatially related granites. With the exception of the Cala granite (352 ± 4 Ma), which represents an older intrusion, the bulk of samples yield ages that cluster around 340 ± 3 Ma: the Santa Olalla tonalite (341.5 ± 3 Ma), the Sultana hornblende tonalite (341 ± 3 Ma), a mingling area at the contact between the Aguablanca and Santa Olalla stocks (341 ± 1.5 Ma), the Garrote granite (339 ± 3 Ma), the Teuler granite (338 ± 2 Ma), and dioritic dykes from the Aguablanca stock (338.6 ± 0.8 Ma). The Bodonal–Cala porphyry, which has also been dated (530 ± 3 Ma), comprises a group of sub-volcanic rhyolitic intrusions belonging to the Bodonal–Cala volcano-sedimentary complex, which hosts the igneous rocks. The knowledge that emplacement of the Aguablanca deposit was related to episodic transtensional tectonic stages during the Variscan orogeny will be fundamental in future mineral exploration in the Ossa–Morena Zone.
Was Baltica right-way-up or upside-down in the Neoproterozoic?
Authors: Cawood Peter A. , Pisarevsky Sergei A.
Published: August 2006

Baltica is a progeny of Rodinia, born from the breakup of the supercontinent in the Neoproterozoic. Within Rodinia, Baltica is generally placed adjacent to NE Laurentia but in a variety of configurations, which vary by up to 3000 km along the strike of the Laurentian margin and include both right-way-up and upside-down orientations (current coordinates). Geological and palaeomagnetic data show that the only viable reconstruction juxtaposes the western Scandinavian margin of Baltica, in its right-way-up orientation, against the Rockall–Scotland–SE Greenland segment of Laurentia.
Middle Pleistocene glacier behaviour in the Mediterranean: sedimentological evidence from the Pindus Mountains, Greece
Authors: Hughes P.D. , Gibbard P.L. , Woodward J.C.
Published: August 2006

Detailed sedimentological analyses of diamicton sequences in two areas of the Pindus Mountains, Greece, indicate multiple episodes of glacier advance and retreat during cold stages of the Middle-Pleistocene. These glacial sequences represent some of the most southerly in Europe and are important archives of regional and global climate change. The Pindus glaciers were relatively small by world standards and would have been highly responsive to changes in air temperature and precipitation. On Mount Tymphi, at least three phases of glacier advance are recorded within deposits assigned to the Skamnellian Stage (MIS 12). Further north on Mount Smolikas, a thick multiple diamicton sequence records evidence for multiple glacier advances during both the Skamnellian Stage and the Vlasian Stage (MIS 6). These records highlight the dynamic nature of glacier behaviour in the Mediterranean mountains during the Middle Pleistocene and provide new evidence for unstable cold stage climates.
Zircon thermometry and U–Pb ion-microprobe dating of the gabbros and associated migmatites of the Variscan Toledo Anatectic Complex, Central Iberia
Authors: Bea F. , Montero P.G. , Gonzalez-Lodeiro F. , Talavera C. , Molina J.F. , Scarrow J.H. , Whitehouse M.J. , Zinger T.
Published: August 2006

In the Central Iberian Zone there are several large thermal domes in which small bodies of ultramafic, mafic and intermediate rocks appear intimately associated with crustal granites and migmatites. The closest spatial association between the ultramafic, mafic and intermediate rocks and migmatites is in the Toledo Anatectic Complex, where field relationships suggest that these rocks are coeval and have an age close to 340 Ma. This, and the recent discovery in the neighbouring Ossa Morena Zone of a large mid-crustal seismic reflector interpreted as a 335–350 Ma mafic sill, reinforce the hypothesis that heat for crustal melting was supplied from early Variscan mantle magmas emplaced in the middle crust. However, precise ion-microprobe U–Pb zircon dating and Ti-in-zircon thermometry in Toledo do not support this idea. Whereas the mean age of four mafic bodies is 307 ± 2 Ma, the migmatites are
c
. 25 Ma older. The migmatites hosting ultramafic, mafic and intermediate bodies have the same age and Ti-in-zircon temperatures as migmatites far from any mafic intrusion. These data reveal that ultramafic, mafic and intermediate magmas are late Variscan; they were emplaced in already cooling anatectic zones once the extensional collapse was initiated, and their thermal impact on the mid-crustal Variscan anatexis of Central Iberia was negligible.
Shale smear along large faults: continuity of smear and the fault seal capacity
Authors: Færseth Roald B.
Published: August 2006

Data from faults with core recovery offshore Norway and from outcrops in study areas onshore demonstrate the development and continuity of smear along large (seismic-scale) faults. Smear along these faults is typically associated with thick (tens of metres) shale source layers and fault segments that are slightly offset, where the overlap between the segments creates an extensional dip relay. It is demonstrated that rock types other than shale, such as coal, siltstones and carbonates, may smear and thereby contribute to the low- permeable fault gouge. A critical threshold for the shale smear factor (SSF), given by the fault throw divided by the thickness of the shale source layer, is established to separate continuous and discontinuous smears. An SSF ≤4 is likely to correspond to a continuous smear along large faults and thereby to a sealing membrane on the fault surface. For small (subseismic) faults, a continuous smear can be maintained for both shale and coal source layers for much higher smear factors compared with large faults. The continuity of smear associated with small faults also displays a greater variation (SSF in the range of 1–50), to become less predictable than smear along large faults.
Endocrine Functions of Adipose Tissue
Authors: Waki Hironori , Tontonoz Peter
Published: August 2006

Obesity is a risk factor for type 2 diabetes, dyslipidemia, and cardiovascular disease. Dissection of the molecular mechanisms underlying obesity and its relationship to insulin resistance and the metabolic syndrome are essential for developing new strategies for prevention and treatment of these disorders. Both excess adipose tissue and lack of adipose tissue cause insulin resistance and dyslipidemia, suggesting that normal fat is required for the maintenance of systemic glucose and lipid homeostasis. Recent advances in obesity research have led to the recognition that adipose tissue is an active endocrine organ that secretes multiple bioactive factors termed adipokines. Secretion of adipokines provides a link between adipose tissue lipid accumulation and the metabolic function of other tissues such as liver and muscle. Dysregulation of adipokines is emerging as an important mechanism by which adipose tissue contributes to systemic insulin resistance and metabolic disease.
Stem cell-derived Sca-1+ progenitors differentiate into smooth muscle cells, which is mediated by collagen IV-integrin α1/β1/αv and PDGF receptor pathways
Authors: Xiao Qingzhong , Zeng Lingfang , Zhang Zhongyi , Hu Yanhua , Xu Qingbo
Published: August 2006

Embryonic stem (ES) cells can differentiate into smooth muscle cells (SMCs) that can be used for tissue engineering and repair of damaged organs. However, little is known about the molecular mechanisms of differentiation in these cells. In the present study, we found collagen IV can promote ES cells to differentiate into stem cell antigen-1-positive (Sca-1+) progenitor cells and SMCs. Pretreatment of ES cells with antibodies against collagen IV significantly inhibited SMC marker expression. To further elucidate the effect of collagen IV on the induction and maintenance of SMC differentiation, Sca-1+ progenitor cells were isolated with magnetic beads, placed in collagen-IV-coated flasks, and cultured in differentiation medium with or without platelet-derived growth factor (PDGF)-BB for 6–90 days. Both immunostaining and fluorescence-activated cell sorter analyses revealed that the majority of these cells were positive for SMC-specific markers. Pretreatment of Sca-1+ progenitors with antibodies against integrin α1, αv, and β1, but not β3, inhibited focal adhesion kinase (FAK) and paxillin phosphorylation and resulted in a marked inhibition of SMC differentiation. Various tyrosine kinase inhibitors, and specific siRNA for phosphatidylinositol 3-kinase (PI 3-kinase) and PDGF receptor-β significantly inhibited SMC marker expression. Taken together, we demonstrate for the first time that collagen IV plays a crucial role in the early stage of SMC differentiation and that integrin (α1, β1, and αv)-FAK-PI 3-kinase-mitogen-activated protein kinase and PDGF receptor-β signaling pathways are involved in SMC differentiation.
Low shear stress preferentially enhances IKK activity through selective sources of ROS for persistent activation of NF-κB in endothelial cells
Authors: Mohan Sumathy , Koyoma Koichi , Thangasamy Amalraj , Nakano Hiroyasu , Glickman Randolph D. , Mohan Natarajan
Published: August 2006

NF-κB signaling pathway has been known to play a major role in the pathological process of atherogenesis. Unlike high shear stress, in which the NF-κB activity is transient, our earlier studies have demonstrated a persistent activation of NF-κB in response to low shear stress in human aortic endothelial cells. These findings partially explained why low shear regions that exist at bifurcations of arteries are prone to atherosclerosis, unlike the relatively atheroprotective high shear regions. In the present study, we further investigated 1) the role of NF-κB signaling kinases (IKKα and β) that may be responsible for the sustained activation of NF-κB in low shear stress and 2) the regulation of these kinases by reactive oxygen species (ROS). Our results demonstrate that not only is a significant proportion of low shear-induced-kinase activity is contributed by IKKβ, but it is also persistently induced for a prolonged time frame. The IKK activity (both α and β) is blocked by apocynin (400 μM), a specific NADPH oxidase inhibitor, and diphenyleneiodonium chloride (DPI; 10 μM), an inhibitor of flavin-containing oxidases like NADPH oxidases. Determination of ROS also demonstrated an increased generation in low shear stress that could be blocked by DPI. These results suggest that the source of ROS generation in endothelial cells in response to low shear stress is NADPH oxidase. The DPI-inhibitable component of ROS is the primary regulator of specific upstream kinases that determine the persistent NF-κB activation selectively in low shear-induced endothelial cells.