bluuebunny/crossref_metadata_2025_split huggingface dataset:
Natural Genetic Variation ofArabidopsis thalianaIs Geographically Structured in the Iberian Peninsula
Authors: Picó F Xavier , Méndez-Vigo Belén , Martínez-Zapater José M , Alonso-Blanco Carlos 
Published: August 2008

AbstractTo understand the demographic history of Arabidopsis thaliana within its native geographical range, we have studied its genetic structure in the Iberian Peninsula region. We have analyzed the amount and spatial distribution of A. thaliana genetic variation by genotyping 268 individuals sampled in 100 natural populations from the Iberian Peninsula. Analyses of 175 individuals from 7 of these populations, with 20 chloroplast and nuclear microsatellite loci and 109 common single nucleotide polymorphisms, show significant population differentiation and isolation by distance. In addition, analyses of one genotype from 100 populations detected significant isolation by distance over the entire Iberian Peninsula, as well as among six Iberian subregions. Analyses of these 100 genotypes with different model-based clustering algorithms inferred four genetic clusters, which show a clear-cut geographical differentiation pattern. On the other hand, clustering analysis of a worldwide sample showed a west–east Eurasian longitudinal spatial gradient of the commonest Iberian genetic cluster. These results indicate that A. thaliana genetic variation displays significant regional structure and consistently support the hypothesis that Iberia has been a glacial refugium for A. thaliana. Furthermore, the Iberian geographical structure indicates a complex regional population dynamics, suggesting that this region contained multiple Pleistocene refugia with a different contribution to the postglacial colonization of Europe.
Intraspecific Phylogeographic Genomics From Multiple Complete mtDNA Genomes in Atlantic Cod (Gadus morhua): Origins of the “Codmother,” Transatlantic Vicariance and Midglacial Population Expansion
Authors: Carr Steven M , Marshall H Dawn 
Published: August 2008

Abstract
On the basis of multiple complete mitochondrial DNA genome sequences, we describe the temporal phylogeography of Atlantic cod (Gadus morhua), a lineage that has undergone a complex pattern of vicariant evolution, postglacial demographic shifts, and historic sharp population declines due to fishing and/or environmental shifts. Each of 32 fish from four spawning aggregations from the northwest Atlantic and Norway has a unique mtDNA sequence, which differs by 6–60 substitutions. Phylogenetic analysis identifies six major haplogroups that range in age from 37 to 75 KYA. The widespread haplotype identified by previous single-locus analyses at the center of a “star phylogeny” is shown to be a paraphyletic assemblage of genome lineages. The coalescent that includes all cod occurs 162 KYA. The most basal clade comprises two fish from the western Atlantic. The most recent superclade that includes all fish examined from Norway, and which includes 84% of all fish examined, dates to 128 KYA at the Sangamon/Würm interglacial, when ocean depths on continental shelves would have favored transcontinental movement. The pairwise mismatch distribution dates population expansion of this superclade to the middle of the Wisconsinan/Weichsel glaciation 59 KYA, rather than to a postglacial emergence from a marine refugium 12 KYA, or to more recent historic events. We discuss alternative scenarios for the expansion and distribution of the descendants of the “codmother” in the North Atlantic. Mitochondrial phylogenomic analyses generate highly resolved trees that enable fine-scale tests of temporal hypotheses with an accuracy not possible with single-locus methods.
Thelytokous Parthenogenesis in Unmated Queen Honeybees (Apis mellifera capensis): Central Fusion and High Recombination Rates
Authors: Oldroyd Benjamin P , Allsopp Michael H , Gloag Rosalyn S , Lim Julianne , Jordan Lyndon A , Beekman Madeleine 
Published: August 2008

Abstract
The subspecies of honeybee indigenous to the Cape region of South Africa, Apis mellifera capensis, is unique because a high proportion of unmated workers can lay eggs that develop into females via thelytokous parthenogenesis involving central fusion of meiotic products. This ability allows pseudoclonal lineages of workers to establish, which are presently widespread as reproductive parasites within the honeybee populations of South Africa. Successful long-term propagation of a parthenogen requires the maintenance of heterozygosity at the sex locus, which in honeybees must be heterozygous for the expression of female traits. Thus, in successful lineages of parasitic workers, recombination events are reduced by an order of magnitude relative to meiosis in queens of other honeybee subspecies. Here we show that in unmated A. m. capensis queens treated to induce oviposition, no such reduction in recombination occurs, indicating that thelytoky and reduced recombination are not controlled by the same gene. Our virgin queens were able to lay both arrhenotokous male-producing haploid eggs and thelytokous female-producing diploid eggs at the same time, with evidence that they have some voluntary control over which kind of egg was laid. If so, they are able to influence the kind of second-division meiosis that occurs in their eggs post partum.
Multilocus Patterns of Nucleotide Polymorphism and the Demographic History of Populus tremula
Authors: Ingvarsson Pär K 
Published: August 2008

Abstract
I have studied nucleotide polymorphism and linkage disequilibrium using multilocus data from 77 fragments, with an average length of fragments of 550 bp, in the deciduous tree Populus tremula (Salicaceae). The frequency spectrum across loci showed a modest excess of mutations segregating at low frequency and a marked excess of high-frequency derived mutations at silent sites, relative to neutral expectations. These excesses were also seen at replacement sites, but were not so pronounced for high-frequency derived mutations. There was a marked excess of low-frequency mutations at replacement sites, likely indicating deleterious amino acid-changing mutations that segregate at low frequencies in P. tremula. I used approximate Bayesian computation (ABC) to evaluate a number of different demographic scenarios and to estimate parameters for the best-fitting model. The data were found to be consistent with a historical reduction in the effective population size of P. tremula through a bottleneck. The timing inferred for this bottleneck is largely consistent with geological data and with data from several other long-lived plant species. The results show that P. tremula harbors substantial levels of nucleotide polymorphism with the posterior mode of the scaled mutation rate, θ = 0.0177 across loci. The ABC analyses also provided an estimate of the scaled recombination rate that indicates that recombination rates in P. tremula are likely to be 2–10 times higher than the mutation rate. This study reinforces the notion that linkage disequilibrium is low and decays to negligible levels within a few hundred base pairs in P. tremula.
Investigation ofMcp1as a Quantitative Trait Gene for Prion Disease Incubation Time in Mouse
Authors: O'Shea Marie , Maytham Emma G , Linehan Jackie M , Brandner Sebastian , Collinge John , Lloyd Sarah E 
Published: August 2008

AbstractThe genetic basis of prion disease incubation time is principally determined by polymorphisms in the prion protein gene, Prnp. However, it is now known that other genetic factors are important. Several quantitative trait loci (QTL) have been identified across the genome including a broad region of linkage on Mmu11. Monocyte chemoattractant protein 1 (MCP-1) maps to this region and has been associated with microglial activation and reduced survival in the ME7 mouse scrapie model of prion disease. We have identified 10 polymorphisms, 3 of which are nonsynonomous, in Mcp1 between “long” (CAST) and “short” (SJL or NZW) incubation-time mouse strains. Crosses between these strains and Mcp1−/− mice inoculated with the Chandler/RML mouse scrapie prion strain formed the basis of a quantitative complementation test. In these models loss of Mcp1 did not show an increase in incubation time suggesting that the effects of Mcp1 may be specific to the ME7 prion strain and that Mcp1 does not contribute to the QTL described on Mmu11.
The Ku Complex in Silencing the Cryptic Mating-Type Loci ofSaccharomyces cerevisiae
Authors: Patterson Erin E , Fox Catherine A 
Published: August 2008

AbstractSir1 establishes transcriptional silencing at the cryptic mating-type loci HMR and HML (HM loci) by recruiting the three other Sir proteins, Sir2, -3, and -4, that function directly in silenced chromatin. However, SIR1-independent mechanisms also contribute to recruiting the Sir2–4 proteins to the HM loci. A screen to elucidate SIR1-independent mechanisms that establish HMR silencing identified a mutation in YKU80. The role for Ku in silencing both HMR and HML was masked by SIR1. Ku's role in silencing the HM loci was distinct from its shared role with the nuclear architecture protein Esc1 in tethering the HM loci and telomeres to the nuclear periphery. The ability of high-copy SIR4 to rescue HMR silencing defects in sir1Δ cells required Ku, and chromatin immunoprecipitation (ChIP) experiments provided evidence that Ku contributed to Sir4's physical association with the HM loci in vivo. Additional ChIP experiments provided evidence that Ku functioned directly at the HM loci. Thus Ku and Sir1 had overlapping roles in silencing the HM loci.
Modulation of Inflammatory Responses After Global Ischemia by Transplanted Umbilical Cord Matrix Stem Cells
Authors: Hirko Aaron C. , Dallasen Renee , Jomura Sachiko , Xu Yan 
Published: August 2008

Abstract
Rat umbilical cord matrix (RUCM) cells are stem-cell-like cells and have been shown to reduce neuronal loss in the selectively vulnerable brain regions after cardiac arrest (CA). Here, we investigate whether this protection is mediated by the RUCM cells' modulation of the postischemia inflammation responses, which have long been implicated as a secondary mechanism of injury following ischemia. Brain sections were examined immunohistochemically for glial fibrillary acidic protein (GFAP), vimentin, and nestin as markers for astroglia and reactive astrogliosis, Ricinus Communis Agglutinin-1 (RCA-1) as a marker for microglia, and Ki67 as a marker for cell proliferation. Rats were randomly assigned to six experimental groups: (1) 8-minute CA without treatment, (2) 8-minute CA pre-treated with culture medium injection, (3) 8-minute CA pre-treated with RUCM cells, (4) sham-operated CA, (5) medium injection without CA, and (6) RUCM cell transplantation without CA. Groups 1–3 have significantly higher Ki67+ cell counts and higher GFAP+ immunoreactivity in the hippocampal Cornu Ammonis layer 1 (CA1) region compared to groups 4–6, irrespective of treatment. Groups 1 and 2 have highly elevated GFAP+, vimentin+, and nestin+ immunoreactivity, indicating reactive astrogliosis. Strikingly, RUCM cell treatment nearly completely inhibited the appearance of vimentin+ and greatly reduced nestin+ reactive astrocytes. RUCM cell treatment also greatly reduced RCA-1 staining, which is found to strongly correlate with the neuronal loss in the CA1 region. Our study indicates that treatment with stem-cell-like RUCM cells modulates the inflammatory response to global ischemia and renders neuronal protection by preventing permanent damage to the selectively vulnerable astrocytes in the CA1 region.
Disclosure of potential conflicts of interest is found at the end of this article.
Enrichment and Differentiation of Human Germ-Like Cells Mediated by Feeder Cells and Basic Fibroblast Growth Factor Signaling
Authors: West Franklin D. , Machacek Dave W. , Boyd Nolan L. , Pandiyan Kurinji , Robbins Kelly R. , Stice Steven L. 
Published: August 2008

Abstract
Human embryonic stem cells (hESCs) have recently demonstrated the potential for differentiation into germ-like cells in vitro. This provides a novel model for understanding human germ cell development and human infertility. Mouse embryonic fibroblast (MEF) feeders and basic fibroblast growth factor (bFGF) are two sources of signaling that are essential for primary culture of germ cells, yet their role has not been examined in the derivation of germ-like cells from hESCs. Here protein and gene expression demonstrated that both MEF feeders and bFGF can significantly enrich germ cell differentiation from hESCs. Under enriched differentiation conditions, flow cytometry analysis proved 69% of cells to be positive for DDX4 and POU5F1 protein expression, consistent with the germ cell lineage. Importantly, removal of bFGF from feeder-free cultures resulted in a 50% decrease in POU5F1- and DDX4-positive cells. Quantitative reverse transcription-polymerase chain reaction analysis established that bFGF signaling resulted in an upregulation of genes involved in germ cell differentiation with or without feeders; however, feeder conditions caused significant upregulation of premigratory/migratory (Ifitm3, DAZL, NANOG, and POU5F1) and postmigratory (PIWIL2, PUM2) genes, along with the meiotic markers SYCP3 and MLH1. After further differentiation, &gt;90% of cells expressed the meiotic proteins SYCP3 and MLH1. This is the first demonstration that signaling from MEF feeders and bFGF can induce a highly enriched population of germ-like cells derived from hESCs, thus providing a critically needed model for further investigation of human germ cell development and signaling.
Disclosure of potential conflicts of interest is found at the end of this article.
In Vitro Optimization of Dexamethasone Phosphate Delivery by Iontophoresis
Authors: Sylvestre Jean-Philippe , Guy Richard H , Delgado-Charro M Begoña 
Published: August 2008

Background and Purpose
This study was designed to evaluate the effects of competing ions and electroosmosis on the transdermal iontophoresis of dexamethasone phosphate (Dex-Phos) and to identify the optimal conditions for its delivery.

Methods
The experiments were performed using pig skin, in side-by-side diffusion cells (0.78 cm2), passing a constant current of 0.3 mA via Ag-AgCl electrodes. Dex-Phos transport was quantified for donor solutions (anodal and cathodal) containing different drug concentrations, with and without background electrolyte. Electrotransport of co-ion, citrate, and counterions Na+ and K+ also was quantified. The contribution of electroosmosis was evaluated by measuring the transport of the neutral marker (mannitol).

Results
Electromigration was the dominant mechanism of drug iontophoresis, and reduction in electroosmotic flow directed against the cathodic delivery of Dex-Phos did not improve drug delivery. The Dex-Phos flux from the cathode was found to be optimal (transport number of ∼0.012) when background electrolyte was excluded from the formulation. In this case, transport of the drug is limited principally by the competition with counterions (mainly Na+ with a transport number of ∼0.8) and the mobility of the drug in the membrane.

Discussion and Conclusion
Dex-Phos must be delivered from the cathode and formulated rationally, excluding mobile co-anions, to achieve optimal iontophoretic delivery.
The Cooperative University of Iowa / Iowa State University MPH Program
Authors: Bickett-Weddle Danelle A. , Aquilino Mary L. , Roth James A. 
Published: August 2008

Public health is an important component of veterinary medicine. In the last 10 years, there has been growing recognition of the need to increase the number of veterinarians trained in public health. The Center for Food Security and Public Health (CFSPH) at Iowa State University (ISU), College of Veterinary Medicine, received a grant from the Centers for Disease Control and Prevention (CDC) to support veterinarians working at CFSPH while pursuing the Master of Public Health degree. CFSPH and ISU administrators worked with the University of Iowa (UI) College of Public Health to establish three cooperative programs for veterinarians to earn the MPH degree. This article describes how these programs were developed and how they operate. (1) Between 2002 and 2005, CFSPH used funds provided by the CDC to support 15 veterinarians as they worked for CFSPH and toward the MPH degree. As the program grew, distance-education methods such as the Internet, Polycom videoconferencing, and the Iowa Communications Network (ICN) were incorporated. (2) A concurrent DVM/MPH degree is now offered; students can complete both degrees in four years. As of January 2008, three students have received their DVM and MPH degrees and 16 students are enrolled in the program. (3) In June 2007, the UI and ISU launched a distance MPH program for veterinarians working in private practice, industry, and government. Eight veterinarians are participating in the program, which includes two two-week, in-person summer sessions, with the remainder of the coursework taken at a distance via the Internet.
Enhancing Food-Safety Education through Shared Teaching Resources
Authors: McDonald Jeannette 
Published: August 2008

The American public is concerned about food safety, and there is a growing realization that we are ill equipped to handle major food-borne illness outbreaks and bioterrorism. Since veterinary medicine plays an important role in assuring the safety of our nation's food supply, we would like to present to veterinary and public health educators a newly emerging resource for food-safety educational materials. This article describes an integrative collaborative approach for the creation and dissemination of engaging food-safety teaching resources for veterinary faculty. This USDA-funded project, Design to Dissemination: Developing Materials and Repository for Integrative Veterinary Food Safety Education, involves expert teachers in diverse fields and from many veterinary schools. The purpose of the project is to create materials that teach students food safety from farm to fork, and it offers teachers clinically relevant teaching resources that are difficult to create or locate. The educational materials are being created as smaller “building blocks” of content, commonly referred to as “learning objects” (LOs), focused on individual learning objectives. These learning objects are placed in the Veterinary Food Safety Education Learning Object Repository, where they are catalogued, stored, and kept accessible and where faculty can search, evaluate, and download teaching materials to use in their courses. In this way the learning objects can be more easily shared and reused or repurposed for other courses and applications. With this article we hope to excite faculty in veterinary schools and public-health programs and encourage them to use the repository and participate in piloting the educational materials.
Development and Evaluation of an Online Computer-Aided Learning (CAL) Package to Promote Small-Animal Welfare
Authors: Denwood Matthew , Dale Vicki H.M. , Yam Philippa 
Published: August 2008

Rationale for the study – The aims of the study, conducted as a student research project in the 2004–5 session, were to develop an interactive, online computer-aided learning (CAL) package on the topic of small-animal husbandry; to validate the resource as a suitable lecture replacement for first-year veterinary students; and to raise awareness of current guidelines and legislation relating to small-animal housing among local catteries and kennels and in the wider community. Methodology – Quantitative feedback was collected from student and teaching staff using paper-based questionnaires. Qualitative feedback was gathered from open questionnaire responses and through focus-group discussions with students. Student examination marks were compared for 2004 and 2005, allowing a comparison of student performance before and after the replacement of the traditional lecture with the CAL package. Ethical approval for the study was granted by the faculty's Ethics Committee. Results and conclusions – The CAL package on small-animal housing was well received by teaching staff and students; student performance in examinations improved after the introduction of the CAL program, suggesting that it provides a suitable alternative to didactic teaching. The creation and distribution of the CAL package on CD-ROM and its availability via the Internet are intended to contribute to small-animal welfare education in local catteries and kennels and further afield. The package sets a precedent for the development of more Internet-based, student-authored CAL packages in the future, providing additional resources for independent learning.
Yield, creep, and wear properties of ultra high molecular weight polyethylene processed by high velocity compaction
Authors: Jauffrès D. , Lame O. , Vigier G. , Doré F. , Fridrici V. 
Published: August 2008

AbstractA new processing method, high velocity compaction (HVC), is particularly adapted to process ultra high molecular weight polyethylene (UHMWPE). In a previous study, it has been shown that UHMWPE processed by HVC exhibits superior Young's modulus and significant ductility, owing to the preservation of nascent high crystallinity and high‐quality sintering (Jauffrès et al., Polymer 2007, 48, 6374). In this article, a comparative study of yield, creep, and wear properties of HVC–UHMWPE and compression‐molded UHMWPE is reported. HVC–UHMWPE has an enhanced resistance to plastic deformation, likely due to its particular microstructure that improves its wear resistance. Concerning creep resistance, HVC–UHMWPE also exhibits enhanced performances thanks to its higher crystallinity. Consequently, HVC could be a new mean to improve UHMWPE performance for a wide range of applications, requiring high wear resistance, both in industrial and biomedical fields. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
New lower matrix bounds for the solution of the continuous algebraic lyapunov equation
Authors: Davies Richard , Shi Peng , Wiltshire Ron 
Published: August 2008

AbstractNew lower matrix bounds are derived for the solution of the continuous algebraic Lyapunov equation (CALE). Following each bound derivation, an iterative algorithm is proposed to derive tighter matrix bounds. In comparison to existing results, the presented results are more concise and are always valid when the CALE has a non‐negative definite solution. We finally give numerical examples to show the effectiveness of the derived bounds and make comparisons with existing results. Copyright © 2008 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society
“Kontakte” – Reflexionen naturwissenschaftlich‐technischer Innovationsprozesse in der frühen Elektronischen Musik Karlheinz Stockhausens (1952–1960)
Authors: Böhlandt Marco 
Published: August 2008

Abstract“Kontakte” – Reflections of Innovative Processes in Science and Technology in Karlheinz Stockhausen's Early Electronic Music (1952–1960). The following article will give an overview of the interdependence of aesthetic and scientific/technical developments in German composer Karlheinz Stockhausen's early works of electronic music. It is an outline of the major steps in his artistic evolution between the works “Etude (Musique concrète)” and “Kontakte”, their relation to innovations in psychoacoustic and sound‐studio technology as well as the impact, that the works from that period had on the fundamental changes in musical aesthetics during the course of the 20th century.