bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of strain and age differences on the yields of porcine islet isolation: extremely high islet yields from SPF CMS miniature pigs
Authors: Kim Jae Hyeon , Kim Hyoung‐Il , Lee Kang‐Woo , Yu Jae Eun , Kim Sun Hee , Park Ho Sun , Park Chung‐Gyu , Ihm Sung‐Hee , Ha Jongwon , Kim Sang Joon , Lee Hong Kyu , Ahn Curie , Park Kyong Soo 
Published: January 2007

Abstract:  Background:  Porcine pancreas is a potential source of material for islet xenotransplantation. However, the difficulty in isolating islets, because of their fragility and the variability of isolation outcome in donor age and breed, represents a major obstacle to porcine islet xenotransplantation. In this study, we compared the islet isolation yield of specific pathogen‐free (SPF) Chicago Medical School (CMS) miniature pigs with that of another miniature pig breed and market pigs from a local slaughterhouse.Methods:  Nine adult CMS miniature (ACM) pigs (>12 months), six young CMS miniature (YCM) pigs (6–7 months), four adult Prestige World Genetics (PWG) miniature (APM) pigs (>12 months), and 13 adult market (AM) pigs from a local slaughterhouse were used for islet isolation.Results:  The islet yield per gram of pancreas from ACM pigs (9589 ± 2823 IEQ/g) was significantly higher than that from APM pigs (1752 ± 874 IEQ/g, P < 0.05), AM pigs (1931 ± 947 IEQ/g, P < 0.05), or YCM pigs (3460 ± 1985 IEQ/g, P < 0.05). Isolated islets from ACM pigs were significantly larger than those from AM pigs or YCM pigs. The in vitro and in vivo function of isolated islets showed no difference among experimental groups. The pancreases of ACM pigs contained higher mean islet volume density percentages and larger size of islets than those of AM or APM pigs.Conclusions:  We isolated extremely high yields of well‐functioning islets from ACM pigs bred under SPF conditions. SPF CMS miniature pigs should be one of the best porcine islet donors for clinical porcine islet xenotransplantation.
Short‐ and long‐term benefits and detriments to recombination under antagonistic coevolution
Authors: PETERS A. D. , LIVELY C. M. 
Published: January 2007

AbstractWe explored the evolution of recombination under antagonistic coevolution, concentrating on the equilibrium frequencies of modifier alleles causing recombination in initially nonrecombining populations. We found that the equilibrium level of recombination in the host depended not only on parasite virulence, but also on the strength of the modifier allele, and on whether or not the modifier was physically linked to the parasite interaction loci. Nonetheless, the maximum level of recombination for linked loci at equilibrium was about 0.3 (60% of free recombination) for interactions with highly virulent parasites; the level decreased for unlinked modifiers, and for lower levels of parasite virulence. We conclude that recombination spreads because it provides a combination of an immediate (next‐generation) fitness benefit and a delayed (two or more generations) increase in the rate of response to directional selection. The relative impact of these two mechanisms depends on the virulence of parasites early in the spread of the modifier, but a trade‐off between the two dictates the equilibrium modifier frequency for all nonzero virulences that we examined. In addition, population mean fitness was higher in populations at intermediate equilibria than populations fixed for free recombination or no recombination. The difference, however, was not enough on its own to overcome the two‐fold cost of producing males.
Cope's Rule in the Pterosauria, and differing perceptions of Cope's Rule at different taxonomic levels
Authors: HONE D. W. E. , BENTON M. J. 
Published: January 2007

AbstractThe remarkable extinct flying reptiles, the pterosaurs, show increasing body size over 100 million years of the Late Jurassic and Cretaceous, and this seems to be a rare example of a driven trend to large size (Cope's Rule). The size increases continue throughout the long time span, and small forms disappear as larger pterosaurs evolve. Mean wingspan increases through time. Examining for Cope's Rule at a variety of taxonomic levels reveals varying trends within the Pterosauria as a whole, as pterodactyloid pterosaurs increase in size at all levels of examination, but rhamphorhynchoid pterosaurs show both size increase and size decrease in different analyses. These results suggest that analyses testing for Cope's Rule at a single taxonomic level may give misleading results.
A morphospace‐based test for competitive exclusion among flying vertebrates: did birds, bats and pterosaurs get in each other's space?
Authors: MCGOWAN A. J. , DYKE G. J. 
Published: January 2007

AbstractThree vertebrate groups – birds, bats and pterosaurs – have evolved flapping flight over the past 200 million years. This innovation allowed each clade access to new ecological opportunities, but did the diversification of one of these groups inhibit the evolutionary radiation of any of the others? A related question is whether having the wing attached to the hindlimbs in bats and pterosaurs constrained their morphological diversity relative to birds. Fore‐ and hindlimb measurements from 894 specimens were used to construct a morphospace to assess morphological overlap and range, a possible indicator of competition, among the three clades. Neither birds nor bats entered pterosaur morphospace across the Cretaceous–Paleogene (Tertiary) extinction. Bats plot in a separate area from birds, and have a significantly smaller morphological range than either birds or pterosaurs. On the basis of these results, competitive exclusion among the three groups is not supported.
Sounds different: inbreeding depression in sexually selected traits in the cricket Teleogryllus commodus
Authors: DRAYTON J. M. , HUNT J. , BROOKS R. , JENNIONS M. D. 
Published: January 2007

AbstractIf male sexual signalling is honest because it captures genetic variation in condition then traits that are important mate choice cues should be disproportionately affected by inbreeding relative to other traits. To test this, we investigated the effect of brother–sister mating on advertisement calling by male field crickets Teleogryllus commodus. We quantified the effect of one generation of inbreeding on nightly calling effort and five finer‐scale aspects of call structure that have been shown to influence attractiveness. We also quantified inbreeding depression on six life history traits and one morphological trait. Inbreeding significantly reduced hatching success, nymph survival and adult lifespan but had no detectable effect on hatching rate, developmental rate or adult body mass. The effect of inbreeding on sexually selected traits was equivocal. There was no decline in calling effort (seconds of sound production/night) by inbred males, but there were highly significant changes in three of five finer‐scale call parameters. Sexually selected traits clearly vary in their susceptibility to inbreeding depression.
Geographic structure in a widespread plant–mycorrhizal interaction: pines and false truffles
Authors: HOEKSEMA J. D. , THOMPSON J. N. 
Published: January 2007

AbstractMutualistic interactions are likely to exhibit a strong geographic mosaic in their coevolutionary dynamics, but the structure of geographic variation in these interactions is much more poorly characterized than in host–parasite interactions. We used a cross‐inoculation experiment to characterize the scales and patterns at which geographic structure has evolved in an interaction between three pine species and one ectomycorrhizal fungus species along the west coast of North America. We found substantial and contrasting patterns of geographic interaction structure for the plants and fungi. The fungi exhibited a clinal pattern of local adaptation to their host plants across the geographic range of three coastal pines. In contrast, plant growth parameters were unaffected by fungal variation, but varied among plant populations and species. Both plant and fungal performance measures varied strongly with latitude. This set of results indicates that in such widespread species interactions, interacting species may evolve asymmetrically in a geographic mosaic because of differing evolutionary responses to clinally varying biotic and abiotic factors.
Morphological evidence of correlational selection and ecological segregation between dextral and sinistral forms in a polymorphic flatfish, Platichthys stellatus
Authors: BERGSTROM C. A. 
Published: January 2007

AbstractPhenotypic polymorphisms in natural systems are often maintained by ecological selection, but only if niche segregation between morphs exists. Polymorphism for eyed‐side direction is rare among the ∼700 species of flatfish (Pleuronectiformes), and the evolutionary mechanisms that maintain it are unknown. Platichthys stellatus (starry flounder) is a polymorphic pleuronectid flatfish exhibiting large, clinal variation in proportion of left‐eyed (sinistral) morphs, from 50% in California to 100% in Japan. Here I examined multiple traits related to swimming and foraging performance between sinistral and dextral morphs of P. stellatus from 12 sites to investigate if the two morphs differ in ways that may affect function and ecology. Direction of body asymmetry was correlated with several other characters: on an average, dextral morphs had longer, wider caudal peduncles, shorter snouts and fewer gill rakers than sinistral morphs. Although the differences were small in magnitude, they were consistent in direction across samples, implying that dextral and sinistral starry flounder may be targeting different prey types. Morphological differences between morphs were greatest in samples where the chances of competitive interactions between them were the greatest. These results suggest that the two morphs are not ecologically identical, may represent a rare example of divergent selection maintaining polymorphism of asymmetric forms, and that correlational selection between body asymmetry and other characters may be driven by competitive interactions between sinistral and dextral flatfish. This study is one of very few that demonstrates the ecological significance of direction in a species with polymorphic asymmetric forms.
An unexpected influence of widely used significance thresholds on the distribution of reported P‐values
Authors: RIDLEY J. , KOLM N. , FRECKELTON R. P. , GAGE M. J. G. 
Published: January 2007

AbstractWe consider the problematic relationship between publication success and statistical significance in the light of analyses in which we examine the distribution of published probability (P) values across the statistical ‘significance’ range, below the 5% probability threshold. P‐values are often judged according to whether they lie beneath traditionally accepted thresholds (< 0.05, < 0.01, < 0.001, < 0.0001); we examine how these thresholds influence the distribution of reported absolute P‐values in published scientific papers, the majority in biological sciences. We collected published P‐values from three leading journals, and summarized their distribution using the frequencies falling across and within these four threshold values between 0.05 and 0. These published frequencies were then fitted to three complementary null models which allowed us to predict the expected proportions of P‐values in the top and bottom half of each inter‐threshold interval (i.e. those lying below, as opposed to above, each P‐value threshold). Statistical comparison of these predicted proportions, against those actually observed, provides the first empirical evidence for a remarkable excess of probability values being cited on, or just below, each threshold relative to the smoothed theoretical distributions. The pattern is consistent across thresholds and journals, and for whichever theoretical approach used to generate our expected proportions. We discuss this novel finding and its implications for solving the problems of publication bias and selective reporting in evolutionary biology.
Assessing the speed and predictability of local adaptation in invasive California poppies (Eschscholzia californica)
Authors: LEGER E. A. , RICE K. J. 
Published: January 2007

AbstractInsight into the speed and predictability of local adaptation can be gained by studying organisms, such as invasive species, that have recently expanded their geographical ranges. Common garden studies were designed to address these issues with the California poppy,Eschscholzia californica, collected from a wide range of environments in both its native (California) and invasive (Chile) ranges. We found similar patterns of plant trait variation along similar abiotic gradients in plants collected from both areas. Multivariate analysis demonstrated that coastal plants from both areas tended to be shorter, smaller plants with smaller seeds and flowers that germinate and flower later than plants collected from inland locations. In addition, size and fecundity traits in both native and invasive poppies were correlated with average rainfall totals; the plants that grew the largest and were the most fecund during the first year of growth originated from the driest areas. This parallel variation suggests that these traits are adaptive and that these patterns have evolved in Chile during the 110–150 years since introduction.
Macrophyte refuges, prey behaviour and trophic interactions: consequences for lake water clarity
Authors: Genkai‐Kato Motomi 
Published: January 2007

AbstractMacrophytes may enhance grazing on phytoplankton by providing a refuge for zooplankton against fish predation. Loss of macrophytes can trigger sudden degradation of water clarity (regime shift) in lakes. However, the presence of piscivores may drive planktivorous fish to take refuge amongst littoral macrophytes. To address the possibility of regime shifts, I here constructed an empirically based model that combined population dynamics of organisms with game theory for optimal habitat selection, taking into consideration the trophic structure, lake size and eutrophication. The model showed that macrophytes generally acted as a refuge for zooplankton, rather than for fish. The model predicted that regime shifts were more likely in small, shallow lakes and that the presence of macrophytes raised the possibility of regime shifts. The present study demonstrated that the fast dynamics of animal behaviour could lead to regime shifts, in connection with slower variables such as nutrient loading.
Living in the branches: population dynamics and ecological processes in dendritic networks
Authors: Campbell Grant Evan H. , Lowe Winsor H. , Fagan William F. 
Published: January 2007

AbstractSpatial structure regulates and modifies processes at several levels of ecological organization (e.g. individual/genetic, population and community) and is thus a key component of complex systems, where knowledge at a small scale can be insufficient for understanding system behaviour at a larger scale. Recent syntheses outline potential applications of network theory to ecological systems, but do not address the implications of physical structure for network dynamics. There is a specific need to examine how dendritic habitat structure, such as that found in stream, hedgerow and cave networks, influences ecological processes. Although dendritic networks are one type of ecological network, they are distinguished by two fundamental characteristics: (1) both the branches and the nodes serve as habitat, and (2) the specific spatial arrangement and hierarchical organization of these elements interacts with a species’ movement behaviour to alter patterns of population distribution and abundance, and community interactions. Here, we summarize existing theory relating to ecological dynamics in dendritic networks, review empirical studies examining the population‐ and community‐level consequences of these networks, and suggest future research integrating spatial pattern and processes in dendritic systems.
Surfactin and fengycin lipopeptides of Bacillus subtilis as elicitors of induced systemic resistance in plants
Authors: Ongena Marc , Jourdan Emmanuel , Adam Akram , Paquot Michel , Brans Alain , Joris Bernard , Arpigny Jean‐Louis , Thonart Philippe 
Published: January 2007

SummaryMultiple strains of Bacillus spp. were demonstrated to stimulate plant defence responses. However, very little is known about the nature of molecular determinants secreted by these Gram‐positive bacteria that are responsible for the elicitation of the induced systemic resistance (ISR) phenomenon. This study shows that the lipopeptides surfactins and fengycins may be involved in this elicitation process. In bean, pure fengycins and surfactins provided a significant ISR‐mediated protective effect on bean plants, similar to the one induced by living cells of the producing strain S499. Moreover, experiments conducted on bean and tomato plants showed that overexpression of both surfactin and fengycin biosynthetic genes in the naturally poor producer Bacillus subtilis strain 168 was associated with a significant increase in the potential of the derivatives to induce resistance. In tomato cells, key enzymes of the lipoxygenase pathway appeared to be activated in resistant plants following induction by lipopeptide overproducers. To our knowledge, such lipopeptides constitute a novel class of compounds from non‐pathogenic bacteria that can be perceived by plant cells as signals to initiate defence mechanisms.
Molecular characterization of T4‐type bacteriophages in a rice field
Authors: Jia Zhongjun , Ishihara Rie , Nakajima Yasunori , Asakawa Susumu , Kimura Makoto 
Published: January 2007

SummaryBacteriophages, the viruses that infect bacteria, are the most abundant biological entities in the biosphere and play a key role in global biogeochemical cycling. All T4‐type bacteriophage isolates tested so far have a conserved genetic module that encodes the virion components including gene 23 (g23), the major capsid protein. Molecular analysis of the g23 sequence revealed a remarkable level of diversity of T4‐type bacteriophages isolated from rice straw and surface soil in a Japanese rice field. It was found that g23 sequences obtained from the rice field were quite distinctive from those obtained in marine environments. Phylogenetic analysis showed that most of these g23 sequences belonged to two novel subgroups of T4‐type bacteriophages, although some of them were related to well‐studied subgroups of T4‐type bacteriophages, such as marine cyanophage isolates of exoT‐evens.
Soil fungal communities in a Castanea sativa (chestnut) forest producing large quantities of Boletus edulis sensu lato (porcini): where is the mycelium of porcini?
Authors: Peintner Ursula , Iotti Mirco , Klotz Petra , Bonuso Enrico , Zambonelli Alessandra 
Published: January 2007

SummaryA study was conducted in a Castanea sativa forest that produces large quantities of the edible mushroom porcini (Boletus edulis sensu lato). The primary aim was to study porcini mycelia in the soil, and to determine if there were any possible ecological and functional interactions with other dominant soil fungi. Three different approaches were used: collection and morphological identification of fruiting bodies, morphological and molecular identification of ectomycorrhizae by rDNA‐ITS sequence analyses and molecular identification of the soil mycelia by ITS clone libraries. Soil samples were taken directly under basidiomes of Boletus edulis, Boletus aestivalis, Boletus aereus and Boletus pinophilus. Thirty‐nine ectomycorrhizal fungi were identified on root tips whereas 40 fungal species were found in the soil using the cloning technique. The overlap between above‐ and below‐ground fungal communities was very low. Boletus mycelia, compared with other soil fungi, were rare and with scattered distribution, whereas their fruiting bodies dominated the above‐ground fungal community. Only B. aestivalis ectomycorrhizae were relatively abundant and detected as mycelia in the soil. No specific fungus–fungus association was found. Factors triggering formation of mycorrhizae and fructification of porcini appear to be too complex to be simply explained on the basis of the amount of fungal mycelia in the soil.
Host specificity and phylogeography of the prochlorophyte Prochloron sp., an obligate symbiont in didemnid ascidians
Authors: Münchhoff Julia , Hirose Euichi , Maruyama Tadashi , Sunairi Michio , Burns Brendan P. , Neilan Brett A. 
Published: January 2007

Summary Prochloron is an oxygenic photosynthetic bacterium that lives in obligate symbiosis with didemnid ascidians, such as Diplosoma spp., Lissoclinum spp. and Trididemnum spp. This study investigated the genetic diversity of the genus Prochloron by constructing a phylogenetic tree based on the 16S rRNA gene sequences of 27 isolates from 11 species of didemnid ascidians collected from Japan, Australia and the USA. The 27 isolates formed three phylogenetic groups: 22 of the samples were identified to be closely related members of Prochloron. Two samples, isolated from Trididemnum nubilum and Trididemnum clinides, were found to belong to the species Synechocystis trididemni, the closest relative of Prochloron. Three isolates formed a separate group from both Prochloron sp. and S. trididemni, potentially indicating a new symbiotic phylotype. Genomic polymorphism analysis, employing cyanobacterium‐specific highly iterative palindrome 1 repeats, could not delineate the isolates further. For the Prochloron sp. isolates, the phylogenetic outcome was independent of host species and geographic origin of the sample indicating a low level of host specificity, low genetic variation within the taxon and possibly a lack of a host–symbiont relationship during reproductive dispersal. This study contributes significantly to the understanding of Prochloron diversity and phylogeny, and implications for the evolutionary relationship of prochlorophytes, cyanobacteria and chloroplasts are also discussed.
Accurate staging, selective preoperative therapy and optimal surgery improves outcome in rectal cancer: a review of the recent evidence
Authors: Daniels I. R. , Fisher S. E. , Heald R. J. , Moran B. J. 
Published: January 2007

AbstractObjective  The current optimal management of locally advanced rectal cancer has evolved from surgical excision followed by postoperative therapy in patients with involved margins, to an increasing use of a preoperative strategy to ‘down‐stage and/or down‐size’ the tumour. This treatment strategy is based on the relationship of the tumour to the mesorectal fascia, the optimal surgical circumferential resection margin that can be achieved by total mesorectal excision. We have reviewed the recent evidence for this strategy.Method  An electronic literature search using PubMed identified articles on the subject of rectal cancer between January 2000 and December 2005. The search was limited to English language publications with secondary references obtained from key articles. Articles published in high impact factor journals formed the basis of the review, together with articles related to national programmes on the management of rectal cancer. This does lead to a selection bias, particularly as the articles identified had a European bias.Conclusion  The UK NHS Cancer Plan has outlined the basis for the multidisciplinary team (MDT) management of rectal cancer. Advances in preoperative assessment through accurate staging and the recognition of the importance of the relationship of the tumour to the mesorectal fascia has allowed the selection of patients for a preoperative strategy to down‐size/down‐stage the tumour if this fascial layer is involved or threatened. Improvements in the quality of surgical resection through the acceptance of the principle of total mesorectal excision have ensured that optimal surgery remains the cornerstone to successful treatment. Further refinements of the MDT process strive to improve outcome. Accurate radiological staging, optimal surgery and detailed histopathological assessment together with consideration of a preoperative neoadjuvant strategy should now form the basis for current treatment and future research in rectal cancer.