bluuebunny/crossref_metadata_2025 huggingface dataset:
A Maternal Screen for Genes Regulating Drosophila Oocyte Polarity Uncovers New Steps in Meiotic Progression
Authors: Barbosa Vitor , Kimm Naomi , Lehmann Ruth
Published: May 2007

Meiotic checkpoints monitor chromosome status to ensure correct homologous recombination, genomic integrity, and chromosome segregation. In Drosophila, the persistent presence of double-strand DNA breaks (DSB) activates the ATR/Mei-41 checkpoint, delays progression through meiosis, and causes defects in DNA condensation of the oocyte nucleus, the karyosome. Checkpoint activation has also been linked to decreased levels of the TGFα-like molecule Gurken, which controls normal eggshell patterning. We used this easy-to-score eggshell phenotype in a germ-line mosaic screen in Drosophila to identify new genes affecting meiotic progression, DNA condensation, and Gurken signaling. One hundred eighteen new ventralizing mutants on the second chromosome fell into 17 complementation groups. Here we describe the analysis of 8 complementation groups, including Kinesin heavy chain, the SR protein kinase cuaba, the cohesin-related gene dPds5/cohiba, and the Tudor-domain gene montecristo. Our findings challenge the hypothesis that checkpoint activation upon persistent DSBs is exclusively mediated by ATR/Mei-41 kinase and instead reveal a more complex network of interactions that link DSB formation, checkpoint activation, meiotic delay, DNA condensation, and Gurken protein synthesis.
Multiple Functions of Drosophila BLM Helicase in Maintenance of Genome Stability
Authors: McVey Mitch , Andersen Sabrina L , Broze Yuri , Sekelsky Jeff
Published: May 2007

Bloom Syndrome, a rare human disorder characterized by genomic instability and predisposition to cancer, is caused by mutation of BLM, which encodes a RecQ-family DNA helicase. The Drosophila melanogaster ortholog of BLM, DmBlm, is encoded by mus309. Mutations in mus309 cause hypersensitivity to DNA-damaging agents, female sterility, and defects in repairing double-strand breaks (DSBs). To better understand these phenotypes, we isolated novel mus309 alleles. Mutations that delete the N terminus of DmBlm, but not the helicase domain, have DSB repair defects as severe as those caused by null mutations. We found that female sterility is due to a requirement for DmBlm in early embryonic cell cycles; embryos lacking maternally derived DmBlm have anaphase bridges and other mitotic defects. These defects were less severe for the N-terminal deletion alleles, so we used one of these mutations to assay meiotic recombination. Crossovers were decreased to about half the normal rate, and the remaining crossovers were evenly distributed along the chromosome. We also found that spontaneous mitotic crossovers are increased by several orders of magnitude in mus309 mutants. These results demonstrate that DmBlm functions in multiple cellular contexts to promote genome stability.
Contrasting Effects of in Vitro Fertilization and Nuclear Transfer on the Expression of mtDNA Replication Factors
Authors: Bowles Emma J , Lee Joon-Hee , Alberio Ramiro , Lloyd Rhiannon E I , Stekel Dov , Campbell Keith H S , St. John Justin C
Published: May 2007

Mitochondrial DNA (mtDNA) is normally only inherited through the oocyte. However, nuclear transfer (NT), the fusion of a donor cell with an enucleated oocyte, can transmit both donor cell and recipient oocyte mtDNA. mtDNA replication is under the control of nuclear-encoded replication factors, such as polymerase gamma (POLG) and mitochondrial transcription factor A (TFAM). These are first expressed during late preimplantation embryo development. To account for the persistence of donor cell mtDNA, even when introduced at residual levels (mtDNAR), we hypothesized that POLG and TFAM would be upregulated in intra- and interspecific (ovine–ovine) and intergeneric (caprine–ovine) NT embryos when compared to in vitro fertilized (IVF) embryos. For the intra- and interspecific crosses, PolGA (catalytic subunit), PolGB (accessory subunit), and TFAM mRNA were expressed at the 2-cell stage in both nondepleted (mtDNA+) and mtDNAR embryos with protein being expressed up to the 16-cell stage for POLGA and TFAM. However, at the 16-cell stage, there was significantly more PolGA expression in the mtDNAR embryos compared to their mtDNA+ counterparts. Expression for all three genes first matched IVF embryos at the blastocyst stage. In the intergeneric model, POLG was upregulated during preimplantation development. Although these embryos did not persist further than the 16+-cell stage, significantly more mtDNAR embryos reached this stage. However, the vast majority of these embryos were homoplasmic for recipient oocyte mtDNA. The upreglation in mtDNA replication factors was most likely due to the donor cells still expressing these factors prior to NT.
The Genomic Landscape of Short Insertion and Deletion Polymorphisms in the Chicken (Gallus gallus) Genome: A High Frequency of Deletions in Tandem Duplicates
Authors: Brandström Mikael , Ellegren Hans
Published: May 2007

It is increasingly recognized that insertions and deletions (indels) are an important source of genetic as well as phenotypic divergence and diversity. We analyzed length polymorphisms identified through partial (0.25×) shotgun sequencing of three breeds of domestic chicken made by the International Chicken Polymorphism Map Consortium. A data set of 140,484 short indel polymorphisms in unique DNA was identified after filtering for microsatellite structures. There was a significant excess of tandem duplicates at indel sites, with deletions of a duplicate motif outnumbering the generation of duplicates through insertion. Indel density was lower in microchromosomes than in macrochromosomes, in the Z chromosome than in autosomes, and in 100 bp of upstream sequence, 5′-UTR, and first introns than in intergenic DNA and in other introns. Indel density was highly correlated with single nucleotide polymorphism (SNP) density. The mean density of indels in pairwise sequence comparisons was 1.9 × 10−4 indel events/bp, ∼5% the density of SNPs segregating in the chicken genome. The great majority of indels involved a limited number of nucleotides (median 1 bp), with A-rich motifs being overrepresented at indel sites. The overrepresentation of deletions at tandem duplicates indicates that replication slippage in duplicate sequences is a common mechanism behind indel mutation. The correlation between indel and SNP density indicates common effects of mutation and/or selection on the occurrence of indels and point mutations.
Bayesian Mapping of Genomewide Interacting Quantitative Trait Loci for Ordinal Traits
Authors: Yi Nengjun , Banerjee Samprit , Pomp Daniel , Yandell Brian S
Published: May 2007

Development of statistical methods and software for mapping interacting QTL has been the focus of much recent research. We previously developed a Bayesian model selection framework, based on the composite model space approach, for mapping multiple epistatic QTL affecting continuous traits. In this study we extend the composite model space approach to complex ordinal traits in experimental crosses. We jointly model main and epistatic effects of QTL and environmental factors on the basis of the ordinal probit model (also called threshold model) that assumes a latent continuous trait underlies the generation of the ordinal phenotypes through a set of unknown thresholds. A data augmentation approach is developed to jointly generate the latent data and the thresholds. The proposed ordinal probit model, combined with the composite model space framework for continuous traits, offers a convenient way for genomewide interacting QTL analysis of ordinal traits. We illustrate the proposed method by detecting new QTL and epistatic effects for an ordinal trait, dead fetuses, in a F2 intercross of mice. Utility and flexibility of the method are also demonstrated using a simulated data set. Our method has been implemented in the freely available package R/qtlbim, which greatly facilitates the general usage of the Bayesian methodology for genomewide interacting QTL analysis for continuous, binary, and ordinal traits in experimental crosses.
Patterns of Molecular Variation and Evolution in Drosophila americana and Its Relatives
Authors: Maside Xulio , Charlesworth Brian
Published: May 2007

We present the results of a survey of DNA sequence variability at X-linked and autosomal loci in Drosophila americana and of patterns of DNA sequence evolution among D. americana and four other related species in the virilis group of Drosophila. D. americana shows a typical level of silent polymorphism for a Drosophila species, but has an unusually low ratio of nonsynonymous to silent variation. Both D. virilis and D. americana also show a low ratio of nonsynonymous to synonymous substitutions along their respective lineages since the split from their common ancestor. The proportion of amino acid substitutions between D. americana and its relatives that are caused by positive selection, as estimated by extensions of the McDonald–Kreitman test, appears to be unusually high. We cannot, however, exclude the possibility that this reflects a recent increase in the intensity of selection on nonsynonymous mutations in D. americana and D. virilis. We also find that base composition at neutral sites appears to be in overall equilibrium among these species, but there is evidence for departure from equilibrium for codon usage in some lineages.
The Formation of the Polyploid Hybrids From Different Subfamily Fish Crossings and Its Evolutionary Significance
Authors: Liu Shaojun , Qin Qinbo , Xiao Jun , Lu Wenting , Shen Jiamin , Li Wei , Liu Jifang , Duan Wei , Zhang Chun , Tao Min , Zhao Rurong , Yan Jinpeng , Liu Yun
Published: May 2007

This study provides genetic evidences at the chromosome, DNA content, DNA fragment and sequence, and morphological levels to support the successful establishment of the polyploid hybrids of red crucian carp × blunt snout bream, which belonged to a different subfamily of fish (Cyprininae subfamily and Cultrinae subfamily) in the catalog. We successfully obtained the sterile triploid hybrids and bisexual fertile tetraploid hybrids of red crucian carp (RCC) (♀) × blunt snout bream (BSB) (♂) as well as their pentaploid hybrids. The triploid hybrids possessed 124 chromosomes with two sets from RCC and one set from BSB; the tetraploid hybrids had 148 chromosomes with two sets from RCC and two sets from BSB. The females of tetraploid hybrids produced unreduced tetraploid eggs that were fertilized with the haploid sperm of BSB to generate pentaploid hybrids with 172 chromosomes with three sets from BSB and two sets from RCC. The ploidy levels of triploid, tetraploid, and pentaploid hybrids were confirmed by counting chromosomal number, forming chromosomal karyotype, and measuring DNA content and erythrocyte nuclear volume. The similar and different DNA fragments were PCR amplified and sequenced in triploid, tetraploid hybrids, and their parents, indicating their molecular genetic relationship and genetic markers. In addition, this study also presents results about the phenotypes and feeding habits of polyploid hybrids and discusses the formation mechanism of the polyploid hybrids. It is the first report on the formation of the triploid, tetraploid, and pentaploid hybrids by crossing parents with a different chromosome number in vertebrates. The formation of the polyploid hybrids is potentially interesting in both evolution and fish genetic breeding.
A Rho-Binding Protein Kinase C-Like Activity Is Required for the Function of Protein Kinase N in Drosophila Development
Authors: Betson Martha , Settleman Jeffrey
Published: May 2007

The Rho GTPases interact with multiple downstream effectors to exert their biological functions, which include important roles in tissue morphogenesis during the development of multicellular organisms. Among the Rho effectors are the protein kinase N (PKN) proteins, which are protein kinase C (PKC)-like kinases that bind activated Rho GTPases. The PKN proteins are well conserved evolutionarily, but their biological role in any organism is poorly understood. We previously determined that the single Drosophila ortholog of mammalian PKN proteins, Pkn, is a Rho/Rac-binding kinase essential for Drosophila development. By performing “rescue” studies with various Pkn mutant constructs, we have defined the domains of Pkn required for its role during Drosophila development. These studies suggested that Rho, but not Rac binding is important for Pkn function in development. In addition, we determined that the kinase domain of PKC53E, a PKC family kinase, can functionally substitute for the kinase domain of Pkn during development, thereby exemplifying the evolutionary strategy of “combining” functional domains to produce proteins with distinct biological activities. Interestingly, we also identified a requirement for Pkn in wing morphogenesis, thereby revealing the first postembryonic function for Pkn.
Ure2p Function Is Enhanced by Its Prion Domain in Saccharomyces cerevisiae
Authors: Shewmaker Frank , Mull Lori , Nakayashiki Toru , Masison Daniel C , Wickner Reed B
Published: May 2007

The Ure2 protein of Saccharomyces cerevisiae can become a prion (infectious protein). At very low frequencies Ure2p forms an insoluble, infectious amyloid known as [URE3], which is efficiently transmitted to progeny cells or mating partners that consequently lose the normal Ure2p nitrogen regulatory function. The [URE3] prion causes yeast cells to grow slowly, has never been identified in the wild, and confers no obvious phenotypic advantage. An N-terminal asparagine-rich domain determines Ure2p prion-forming ability. Since ure2Δ strains are complemented by plasmids that overexpress truncated forms of Ure2p lacking the prion domain, the existence of the [URE3] prion and the evolutionary conservation of an N-terminal extension have remained mysteries. We find that Ure2p function is actually compromised in vivo by truncation of the prion domain. Moreover, Ure2p stability is diminished without the full-length prion domain. Mca1p, like Ure2p, has an N-terminal Q/N-rich domain whose deletion reduces its steady-state levels. Finally, we demonstrate that the prion domain may affect the interaction of Ure2p with other components of the nitrogen regulation system, specifically the negative regulator of nitrogen catabolic genes, Gzf3p.
The in Silico Map-Based Cloning of Pi36, a Rice Coiled-Coil–Nucleotide-Binding Site–Leucine-Rich Repeat Gene That Confers Race-Specific Resistance to the Blast Fungus
Authors: Liu Xinqiong , Lin Fei , Wang Ling , Pan Qinghua
Published: May 2007

The indica rice variety Kasalath carries Pi36, a gene that determines resistance to Chinese isolates of rice blast and that has been located to a 17-kb interval on chromosome 8. The genomic sequence of the reference japonica variety Nipponbare was used for an in silico prediction of the resistance (R) gene content of the interval and hence for the identification of candidate gene(s) for Pi36. Three such sequences, which all had both a nucleotide-binding site and a leucine-rich repeat motif, were present. The three candidate genes were amplified from the genomic DNA of a number of varieties by long-range PCR, and the resulting amplicons were inserted into pCAMBIA1300 and/or pYLTAC27 vectors to determine sequence polymorphisms correlated to the resistance phenotype and to perform transgenic complementation tests. Constructs containing each candidate gene were transformed into the blast-susceptible variety Q1063, which allowed the identification of Pi36-3 as the functional gene, with the other two candidates being probable pseudogenes. The Pi36-encoded protein is composed of 1056 amino acids, with a single substitution event (Asp to Ser) at residue 590 associated with the resistant phenotype. Pi36 is a single-copy gene in rice and is more closely related to the barley powdery mildew resistance genes Mla1 and Mla6 than to the rice blast R genes Pita, Pib, Pi9, and Piz-t. An RT–PCR analysis showed that Pi36 is constitutively expressed in Kasalath.
Littoral Fish Community Response to Smallmouth Bass Removal from an Adirondack Lake
Authors: Weidel Brian C. , Josephson Daniel C. , Kraft Clifford E.
Published: May 2007

Large‐scale observational studies in eastern Canada and the northeastern USA have concluded that introduced littoral predators are responsible for reductions in native fish diversity and abundance. To determine whether nonnative predator removal could increase native littoral fish abundance, we removed 47,682 smallmouth bass Micropterus dolomieu from a 271‐ha Adirondack lake during a 6‐year period. Two years after removal began, habitat‐stratified snorkel surveys indicated a greater than 90% reduction in smallmouth bass abundance. The relative abundances of six native littoral species increased (4‐90 times preremoval abundances) within 2 years of smallmouth bass removal. Decreased relative predation risk during the experiment reflected the reduction in littoral predators and identified seasonal differences in nearshore predation risk. The smallmouth bass population was resilient to removal, producing strong year‐classes throughout the experiment. Mechanical removal was successful at decreasing smallmouth bass abundance and increasing native fish abundance, but removal must be conducted on a yearly basis to maintain low smallmouth bass population abundance. Our results provide experimental evidence regarding the need to prevent littoral predator introductions in Adirondack waters and offer support for nonnative control wherever native fish species conservation is a management priority.
Mesenchymal Stem Cells Inhibit the Differentiation of Dendritic Cells Through an Interleukin-6-Dependent Mechanism
Authors: Djouad Farida , Charbonnier Louis-Marie , Bouffi Carine , Louis-Plence Pascale , Bony Claire , Apparailly Florence , Cantos Céline , Jorgensen Christian , Noël Danièle
Published: May 2007

Mesenchymal stem cells (MSC) are of particular interest for their potential clinical use in tissue engineering as well as for their capacity to reduce the incidence and severity of graft-versus-host disease in allogeneic transplantation. We have previously shown that MSC-mediated immune suppression acts via the secretion of soluble factor(s) induced upon stimulation. The aim of this study was to identify the molecule(s) involved and the underlying mechanism(s). We show that murine MSC secrete high levels of interleukin (IL)-6 and vascular endothelial growth factor, which are directly correlated to the inhibition of T-cell proliferation. The T-cell activation is partially restored upon addition of a neutralizing anti-IL-6 antibody or the prostaglandin E2 inhibitor indomethacin. Interestingly, no indoleamine 2,3-dioxygenase activity was detected in our conditions. Instead, we show that MSC reduce the expression of major histocompatibility complex class II, CD40, and CD86 costimulatory molecules on mature dendritic cells (DC), which was responsible for a decrease in T-cell proliferation. Moreover, we show that the differentiation of bone marrow progenitors into DC cultured with conditioned supernatants from MSC was partly inhibited through the secretion of IL-6. Altogether, these data suggest that IL-6 is involved in the immunoregulatory mechanism mediated by MSC through a partial inhibition of DC differentiation but is probably not the main mechanism.

Disclosure of potential conflicts of interest is found at the end of this article.
Concise Review: Telomere Biology in Normal and Leukemic Hematopoietic Stem Cells
Authors: Drummond Mark W. , Balabanov Stefan , Holyoake Tessa L. , Brummendorf Tim H.
Published: May 2007

The measurement of telomere length can give an insight into the replicative history of the cells in question. Much of the observed telomere loss occurs at the stem and progenitor cell level, even though these populations express the enzyme telomerase. Telomerase-transfected hematopoietic stem cells (HSC), although able to maintain telomere length, are still limited in terms of ability to undergo sequential transplantation, and other factors require to be addressed to achieve optimal levels of stem cell expansion. Unchecked telomere loss by HSC, meanwhile, would appear to play a significant role in the pathogenesis of bone marrow failure, as observed in the condition dyskeratosis congenita. This heterogeneous inherited condition appears to exhibit telomerase dysfunction as a common final pathogenic mechanism. Although less well-established for acquired marrow failure syndromes, mutations in key telomerase components have been described. The identification of the leukemic stem cell (LSC), along with the desire to target this population with anti-leukemia therapy, demands that telomerase biology be fully understood in this cell compartment. Future studies using primary selected LSC-rich samples are required. A better understanding of telomerase regulation in this population may allow effective targeting of the telomerase enzyme complex using small molecule inhibitors or additional novel approaches.

Disclosure of potential conflicts of interest is found at the end of this article.
Briefing: The ‘Sustainability Shaper’ in south west England
Authors: Goldring L.
Published: May 2007

This briefing article reviews the recently relaunched regional sustainable development framework (RSDF) for the south west of England. In 1999 all UK regions were asked by the government to develop RSDFs to inform policy and delivery. The south west has redeveloped its framework as an online tool called the ‘Sustainability Shaper’. Here the Shaper's coordinators, Sustainability South West (SSW), introduce this new awareness-raising and decision-making tool and outline priorities for its future development and influence.
Energy generation from a Severn Barrage prior to full commissioning
Authors: Watson M. J. , Shaw T. L.
Published: May 2007

The Severn Estuary provides the UK with a unique opportunity to harness a large amount of renewable energy from the tides. A barrage 10 miles (16 km) long has been proposed as a means of harnessing this energy. The scheme would be similar, but on a larger scale, to that in the Rance Estuary, northern France, which has consistently and predictably produced electricity over the last 40 years. The studies presented here illustrate the output patterns of the Severn Barrage once the barrage is closed but before project completion, taking into consideration important factors such as: National Grid integration; environmental sensitivities and turbine and pumping characteristics. Assuming the main determine and of operating procedure is production of maximum energy, total barrage output could be 33 TWh by project completion. This is equivalent to almost two years of output from the completed scheme. Furthermore, if barrage closure were to occur earlier than previously envisaged, significantly more electricity would be produced during the construction phase, thus further enhancing the projects economic prospects.
Interdisciplinary perspectives on environmental appraisal and valuation techniques
Authors: Hammond G. P. , Winnett A. B.
Published: May 2007

Techniques of environmental appraisal and valuation play an important role in the context of sustainability assessment. They are at the heart of methods for quantifying economic and social costs and benefits, as well as the direct ecological impacts that are an inevitable side-effect of material ‘progress’. Concepts such as the physical life cycle of products and processes, and the need for clearly defined system boundaries, are key elements in environmental problem-solving. However, some economists would claim that, as a ‘normative’ discipline, their methods can be extended to incorporate all of society's environmental concerns. In contrast, engineers and environmental professionals have at times argued that economic techniques (such as cost–benefit analyses) may well obscure the impacts of different courses of action, and that decision makers consequently become less well informed rather than the reverse. Aggregate decision criteria, for example, often conceal the weighing of various impacts. By contrast, the sort of ‘prescriptive’ analytical tools emanating from engineering and the physical sciences can provide alternative insights that complement those that spring from economics. These include thermodynamic (energy and exergy) analysis and environmental life-cycle assessment. A range of interrelated environmental project appraisal techniques is therefore examined in order to determine their relative merits. Practical examples involving resource (energy and hydraulic oil) use, pollutant emissions, and waste disposal and recycling (of hydraulic oils) indicate that many of these methods can play an important evaluative role as part of an interdisciplinary toolkit within a general systems framework. Nevertheless, caution needs to be used when adopting economic and engineering analysis techniques so as to ensure that they are fit for their sustainability purpose.
Influence of solid solutions on chloride leaching fromwasteforms
Authors: Dyer T. D. , Halliday J. E. , Dhir R. K.
Published: May 2007

The hydration product Friedel's salt (Ca4Al2O6Cl2.10H2O) is frequently encountered in wasteforms solidified and stabilised using Portland cement. The ability of Friedel's salt to form solid solutions plays a role in chloride binding in such matrices. This paper addresses one practical example of this influence by examining the immobilisation of chloride ions from municipal solid waste incinerator fly ash in cementitious matrices also comprising Portland cement and fly ash from coal-fired power generation. Measurements of quantities and structural parameters of Friedel's salt in pastes containing incinerator fly ashes show that chloride ion release is lowest when large quantities of chloride-deficient Friedel's salt is generated. However, chloride is more tightly bound elsewhere in the material, probably in calcium silicate hydrate (CSH) gel. The dissolution of Friedel's salt is modelled using a geochemical modelling program capable of dealing with solid solutions. These observations reinforce the need to incorporate variable phase composition in models for predicting leaching from cementitious matrices containing waste materials.
Spatial and Temporal Variability in Colloid Dispersion as a Function of Groundwater Injection Rate within Atlantic Coastal Plain Sediments
Authors: Seaman J. C. , Bertsch P. M. , Kaplan D. I.
Published: May 2007

A subsurface injection experiment was conducted on the USDOE's Savannah River Site (SRS) to determine the influence of pump‐and‐treat remediation activities on the generation and transport of groundwater colloids. The impact of colloid generation on formation permeability at injection rates ranging from 19 to 132 L min−1 was monitored using a set of six sampling wells radially spaced at approximate distances of 2.0, 3.0, and 4.5 m from a central injection well. Each sampling well was further divided into three discrete sampling depths that were pumped continuously at a rate of ∼0.1 L min−1 throughout the course of the injection experiment. Discrete samples were collected for turbidity and chemical analysis. Turbidity varied greatly between sampling wells and zones within a given well, ranging from <1 to 740 NTU. The two sampling wells closest to the injection well displayed the greatest response in terms of turbidity to increases in injection rate. Transient spikes in turbidity generally corresponded to incremental increases in the injection rate that were followed by a decrease in turbidity to a stable injection rate–dependent level. Mineralogical analysis of the resulting suspensions confirmed the presence of kaolinite, goethite, and to a much lesser degree, quartz and illite, with many of the particles too large (>1 μm) to be readily mobile within the formation. Turbidity measurements taken during this study indicate that colloid mobilization induced by water injection was both spatially and temporally heterogeneous. Furthermore, colloid release did not follow simple predictions based on shear force, presumably due to the complexities encountered in real heterogeneous systems. These findings have important implications to our understanding of how colloids and the co‐contaminants are mobilized in the subsurface environment, as well as for the development of monitoring practices that minimize the creation of colloidal artifacts. Technical and logistical obstacles encountered in conducting such an extensive field experiment are also discussed.
Artificial Neural Network Estimation of Saturated Hydraulic Conductivity
Authors: Agyare W. A. , Park S. J. , Vlek P. L. G.
Published: May 2007

Soil data serve as an important initialization parameter for hydro‐ecological and climatological modeling of water and chemical movement, heat transfer, or land‐use change. Most soil hydraulic properties are difficult to measure and therefore have to be estimated in most cases. Efficient methods for estimating soil hydraulic properties are lacking for tropical soils. This study examines and uses easy‐to‐measure soil properties together with terrain attributes in artificial neural networks (ANNs) to estimate saturated hydraulic conductivity (Ks), one of the key soil hydraulic properties for two pilot sites in the Volta basin of Ghana. It was observed that good data distribution, range, and amounts are prerequisites for good ANN estimation and, therefore, data preprocessing is important for ANN. With adequate and sensitive data, ANN can be used to estimate Ks, using soil properties such as sand, silt, and clay content, bulk density, and organic carbon. Although the inclusion of terrain parameters can improve the estimation of Ks using ANN, they cannot be relied on as the sole input parameters as they yield poor results for the scale considered in this study. The source of training data was found to significantly influence the topsoil Ks, but the subsoil was not sensitive to training data source.
Research in Support of Remediation Activities at the Savannah River Site
Authors: Seaman J. C. , Looney B. B. , Harris M. K.
Published: May 2007

The USDOE Savannah River Site (SRS), an 803‐km2 (310‐mile2) facility located south of Aiken, SC on the upper Atlantic Coastal Plain and bounded to the west by the Savannah River, was established in the 1950s for the production and refinement of nuclear materials. To fulfill this mission during the past 50 years SRS has operated five nuclear reactors, two large chemical separation areas, waste disposal facilities (landfills, waste ponds, waste tanks, and waste stabilization), and a large number of research and logistics support facilities. Contaminants of concern (COC) resulting from site operations include chlorinated solvents, radionuclides, metals, and metalloids, often found as complex mixtures that greatly complicate remediation efforts when compared with civilian industries. The objective of this article is to provide a description of the lithology and hydrostatigraphy of the SRS, as well as a brief history of site operations and research activities as a preface to the current special section of Vadose Zone Journal (VZJ) dedicated to SRS, focusing mainly on issues that are unique to the USDOE complex. Contributions to the special section reflect a diverse range of topics, from hydrologic tracer experiments conducted both within the vadose and saturated zones to studies specifically aimed at identifying geochemical processes controlling the migration and partitioning of specific contaminants (e.g., TCE, 137Cs, U, and Pu) in SRS subsurface environments. Addressing the diverse environmental challenges of the SRS provides a unique opportunity to conduct both fundamental and applied research across a range of experimental scales. Hence, the SRS has been a pioneering force in several areas of environmental research and remediation, often through active interdisciplinary collaboration with researchers from other USDOE facilities, academic and federal institutions, and commercial entities.
Preparation of Macromolecular Heavy Metal Coagulant and Treatment of Wastewater Containing Copper
Authors: Qing Chang , Yu An
Published: May 2007

Many treatment technologies for wastewater containing heavy metals have been developed in recent years, but these technologies have some disadvantages, such as poor removing efficiency and complex operation. For this reason, a macromolecular heavy metal coagulant polyethyleneimine‐sodium xanthogenate (PEX) was prepared by grafting a xanthogenate group to polyethyleneimine. It was determined that PEX has the function of removing both turbidity and copper ions. It was also determined that copper ions and turbidity have a cooperative removal effect with each other in the process of treating wastewater containing both turbidity and copper ions by PEX.    The investigation showed that PEX is an amphoteric polyelectrolyte. At lower pH values, the amino groups of the macromolecule are electrically positive; therefore, turbidity is removed because of electroneutralization coagulation; at higher pH values, both amino groups and xanthogenic radical groups contribute to the removal of heavy metals, as a result of chelation.    Compared with traditional chemical precipitation by calcium oxide and coagulation by an ordinary inorganic coagulant, PEX showed obvious advantages, for example, removing both turbidity and copper ions, higher removal efficiency, lower suitable pH value, and higher floc settlement velocity.
Pilot‐Scale Constructed Wetlands for Petroleum‐Contaminated Groundwater
Authors: Bedessem Marjorie E. , Ferro Ari M. , Hiegel Trevor
Published: May 2007

A pilot study was conducted to determine the feasibility of using constructed treatment wetlands to remediate recovered groundwater from the subsurface of a former refinery site. The pilot system consisted of four subsurface flow treatment cells operated in an upward vertical flow mode and equipped with subsurface aeration lines. The treatment system showed minimal capability for methyl‐tert‐butyl ether removal, but did effectively remove total petroleum hydrocarbons‐deisel range organics and total benzene, toluene, ethylbenzene, and o‐, m‐, and p‐xylenes (total BTEX). Effluent benzene concentrations were less than 0.05 mg/L in 70% of the samples from a treatment cell using subsurface aeration and a wetland sod amendment. Based on 1 year of operating data, cumulative mass removal approached 80% for benzene and 88% for total BTEX.
Use of Oxygen Consumption and Ammonium Excretion to Evaluate the Sublethal Toxicity of Cadmium and Zinc on Litopenaeus schmitti (Burkenroad, 1936, Crustacea)
Authors: Barbieri Edison
Published: May 2007

Penaeid shrimps are important resources for worldwide fisheries and aquaculture. In Brazil, Litopenaeus schmitti (L. schmitti) is a important commercially exploited species and is an ideal animal for studying the impairment caused by the effects of heavy metals that are often detected in coastal areas. The main purpose of the present study was to detect the acute toxicity of cadmium and zinc to L. schmitti and investigate their effects on oxygen consumption and ammonium excretion, investigations that have not been carried out in this species before. First, the acute toxicity of cadmium and zinc to L. schmitti 24, 48, 72, and 96‐hour medium lethal concentration was examined, which resulted in the following values: 0.98, 0.54, 0.32, and 0.18 mg/L for cadmium and 1.64, 1.22, 0.86, and 0.31 mg/L for zinc. Furthermore, we also found that exposure of shrimp to cadmium and zinc caused an inhibition in oxygen consumption of 55.92 and 44.09%, respectively, relative to the control. However, after separate exposure to cadmium and zinc, elevations in ammonium excretion were obtained, which were 174.28 and 162.5% higher than the control, respectively.
Über das Drehspulengalvanometer
Authors: Jaeger W.
Published: May 2007

Einleitung. Empfindlichkeit des Nadelgalvanometers. Drehspulengalvanometer: a) Bewegung eines schwingenden Systems im aperiodischen Grenzfall; b) Bedingungen für die Empfindlichkeit des Drehspulengalvanometers; c) Einfluß der Dämpfung im offenen Stromkreis und des Klemmenwiderstandes auf die Empfindlichkeit; Formeln zur Berechnung der Galvanometerkonstanten; e) Anwendung der Drehspulengalvanometer; f) Ballistische Galvanometer; g) Vergleichung der Empfindlichkeiten des Nadel‐ und Drehspulengalvanometers. Zusammenstellung.
Über die Lichtemission der Kanalstrahlen in Wasserstoff
Authors: Stark J.
Published: May 2007

Teil Träger der Linienspektra. ‐ § 1. Einleitung. § 2. Methoden der Untersuchung. § 3. Aussehen des Doppler‐Effektes. § 4. Konstanz des Doppler‐Effektes innerhalb einer Serie. § 5. Elektrische Ladung des Trägers der Wasserstoffserie. § 6. Elektrische Ladung der Träger von Duplet‐ und Tripletserien, Komplexität des Linienspektrums eines Elementes. § 7. Folgerungen über die Ionisierung und die Lichtemission der chemischen Elemente. § 8. Verbreiterung der Spektrallinien durch Erhöhung der Dichte. § 9. Reflexion und Zerstreuung der Kanalstrahlen. § 10. Die Linie 4688 und das Bandenspektrum in den Kanalstrahlen.

Teil. Translationsgeschwindigkeit und Strahlungsintensität. ‐ § 11. Ionisierung hinter der Kathode, Ursprung der Intensität des Bandenspektrums und der ruhenden Intensität des Linienspektrums. § 12. Parallelismus zwischen Translationsgeschwindigkeit und Temperatur, Vergleich der ruhenden und der bewegten Intensität. § 13. Internsitätsverteilung im Doppler‐Effekt. § 14. Das Intensitätsminimum im Doppler‐Effekt, Forderung für das Auftreten des effektes. § 15. Intensitätsverteilung in einem Serienglied. § 16. Intensitätsverteilung in einer Serie. § 17. Verbreiterung in einer Linienserie durch den Doppler‐Effekt.

Teil. Translationsgeschwindigkeit und Wellenlänge. ‐ § 18. Einleitung, Fehlerquellen. § 19. Verbreiterung der Linien bei normaler Stellung der Beobachtungs‐ und der Translationsrichtung. § 20. Verschiebung der Linienmitte nach Rot. § 21. Verschiebung von Serienlinien durch Erhöhung der Temperatur.
Weitere Mitteilungen über das Saitengalvanometer. Analyse der saitengalvanometrischen Kurven. Masse und Spannung des Quarzfadens und Widerstand gegen die Fadenbewegung
Authors: Einthoven W.
Published: May 2007

1. Einleitung. ‐ 2. Die Grundsätze der befolgten Methode. ‐ 3. die masse der Saite. ‐ 4. Der Widerstand gegen die Saitenbewegung. ‐ 5. Die Beschleunigung.
Oszillatorische Entladung polarisierter Zellen
Authors: Krüger F.
Published: May 2007

I. Einleitung. ‐ II. Theorie. A. Diffusionskapazität. B. Doppelschichten‐ oder Oberflächendichtigkeitskapazität. C. Gleichzeitiges Vorhandensein von Diffusions‐ und Doppelschichtenkapazität. D. Kapazität der Ionenreaktionsgeschwindigkeit. E. Abhängigkeit von der Stromintensität. ‐ III. Versuchsanordnung. ‐ IV. Versuchsergebnisse. A. Quecksilberelektroden. B. Platinelektroden. C. Palladiumelektroden. ‐ V. Schluß. ‐ IV. Zusammenfassung.
Die Präzisionsmessung starker magnetischer Felder; Étalons der magnetischen Feldstärke
Authors: Gans R. , Gmelin P.
Published: May 2007

§ 1. Einleitung. Skizzierung der Methoden. – § 2. Das magnetische Grundétalon. a) Die Inhomogenität des Étalonfeldes. b) Der Proportionalitätsbereich des Grundétalons. – § 3. Die erste Meßmethode. a) Die Eichung der Paschenschen Normalspulen mit der Tangentenbussole. b) Die Inhomogenität des Feldes in den Normalspulen. c) Die absolute Messung der Feldstärke des Grundétalons. – § 4. Die zweite Meßmethode. a) Das wechselseitige Induktionsnormal des Tübinger physikalischen Instituts. b) Die ballistische Induktionsspule. c) Die absolute Messung der Feldstärke des Grundétalons. – § 5. Die Eichung eines Étalons der magnetischen Feldstärke. – Anhang. § 6. Das Normal der Selbstinduktion des Tübinger physikalischen Instituts. – § 7. Die Vergleichung von Siemens & Halskeschen Normalien der wechselseitigen Induktion mit dem Tübinger Normal.
Spektralanalytische Beobachtungen an Kanalstrahlen mit Hilfe großer Dispersion
Authors: Stark J. , Steubing W.
Published: May 2007

§ 1. Methoden. § 2. Fehlerquellen. § 3. Der erste Schwellenwert der Geschwindigkeit für das Auftreten bewegter Intensität. § 4. Die Verteilung der bewegten Intensität im Geschwindigkeitsspektrum der Kanalstrahlen. § 5. Bemerkungen zu Angaben anderer Autoren. § 6. Der zweite Schwellenwert der Geschwindigkeit in der Verteilungskurve der bewegten Intensität. § 7. Relation zwischen der maximalen kinetischen Energie von Kanalstrahlen und der maximalen sie erzeugenden elektrischen Arbeit. § 8. Messungen an dem Doppler‐Effekt reflektierter Kanalstrahlen.
Die Theorie des starren Elektrons in der Kinematik des Relativitätsprinzips
Authors: Born Max
Published: May 2007

Einleitung p. 1. ‐ Erstes Kapitel. Die Kinematik des starren Körpers. § 1. Der starre Körper der alten Mechanik p. 6. § 2. Die Differentialbedingungen der Starrheit p. 11. § 3. Die Kontinuitätsgleichung und die inkompressible Strömung p. 16. § 4. Die geradlinige Translation des starren Körpers p. 19. § 5. Die Hyperbelbewegung p. 25. ‐ Zweites Kapitel. Das Feld des starren Elektrons bei der Hyperbelbewegung. § 6. Retardierte Potentiale und Feldstärken p. 27. § 7. Vergleich der Ausdrücke für die retardierten Potentiale p. 29. § 8. Berechnung der Potentiale bei der Hyperbelbewegung p. 34. § 9. Die Feldstärken bei der Hyperbelbewegung p. 37. § 10. Transformation der Wellengleichung, der Potentiale und Feldstärrken auf ein mitbewegtes Koordinatensystem p. 39. ‐ Drittes Kapitel. Die Dynamik des starren Elektrons bei der Hyperbelbewegung. § 11. Die resultierenden Kräfte und die Bewegungsgleichungen p. 45. § 12. Die resultierenden inneren Kräfte bei der Hyperbelbewegung p. 49. § 13. Die elektrodynamische Ruhmasse p. 54.
Experimentelle und theoretische Grundlagen des elastischen und mechanischen Stoßes
Authors: Ramsauer Carl
Published: May 2007

Einleitung. Entwickelung der beiden Stoßtheorien und bisherige Versuche p. 417. ‐ I. Teil. Der elastische Stoß p. 420. 1. Kap. Theorie des elastischen Stoßes p. 420. § 1. Zylinder von gleichem Material und gleichem Querschnitt p. 420. § 2. Zylinder von beliebigem Material und Querschnitt p. 425. 2. Kap. Versuchsanordnung und Methoden p. 429. § 1. Material der Zylinder p. 429. § 2. Anordnungen zur Hervorbringung eines einwandfreien Longitudinalstoßes p. 431. § 3. Die Spiegelmethode zur Untersuchung des Stoßvorganges im einzelnen p. 434. § 4. Die Schattenmethode zur Messung der Geschwindigkeiten nach dem Stoß p. 443. § 5. Die elektrische Methode zur Messung der Stoßzeiten p. 445. 3. Kap. Versuchsergebnisse p. 446. § 1. Versuche zur Prüfung der Spiegelmethode p. 446. § 2. Versuche an Stahlspiralen p. 451. § 3. Versuche an Kautschukzylindern von gleichem Querschnitt p. 459. § 4. Versuche an Kautschukzylindern von ungleichem Querschnitt p. 470. § 5. Versuche an Zylindern von ungleichem Material p. 473. Zusammenfassung des ersten Teiles p. 477. ‐ II. Teil. Der mechanische Stoß p. 478. 1. Kap. Untersuchung des Idealfalles p. 478. 2. Kap. Die elastischen Vorgänge beim Stoß „starrer”︁ Körper p. 482. 3. Kap. Der Stoß zwischen Kautschukzylindern mit halbkugelförmigem Kopf p. 487. Zusammenfassung des zweiten Teiles p. 493.
Zur Theorie der Röntgenreflexion
Authors: Waller Ivar
Published: May 2007

Der Übergang von dem bei einem kleinen Kristallstück gültigen Gesetz für die reflektierte Intensität zum entsprechenden Gesetz bei einem großen, ideal regelmäßigen Kristall wird untersucht. Im Anschluß daran werden für verschiedene Fälle Reflexionsformeln eines idealen Kristalls aufgestellt.
Zeemaneffekt am Bogen‐ und Funkenspektrum von Molybdän
Authors: Wilhelmy E.
Published: May 2007

In der zweiten Ordnung eines großen Rowlandgitters wurden von 2500‐6000 I.‐Å. bei einer Feldstärke von 34000 Gauss Zeemanaufnahmen des Molybdän‐Bogen‐ und Funkenspektrums gemacht. Im Bogenspektrum wurden die von Catalán gefundenen Multipletts, soweit sie beobachtet werden konnten, sämtlich bestätigt, zwei Gruppen, die Kiess angibt, berichtigt. Im Funkenspektrum wurden neue Terme aufgefunden, die sich in Übereinstimmung befinden mit den Vorstellungen über die Beziehungen zwischen dem Spektrum des neutralen und des einfach ionisierten Atoms.
Density measurement of polymer/CO2 single‐phase solution at high temperature and pressure using a gravimetric method
Authors: Funami Eita , Taki Kentaro , Ohshima Masahiro
Published: May 2007

The densities of two polymer/CO2 single‐phase solutions, poly(ethylene glycol) (PEG)/CO2 and polyethylene (PE)/CO2, were measured at temperatures higher than melting temperature of the polymer under CO2 pressures in the range 0–15 MPa using a newly‐proposed gravimetric method. A magnetic suspension balance (MSB) was used for the density measurement under the high pressure CO2: A thin disc‐shaped platinum plate was submerged in the considered polymer/CO2 single‐phase solution in the MSB high‐pressure cell. The weight of the plate was measured while keeping CO2 pressure and temperature in the sorption cell at a specified level. Since the buoyancy force exerted on the plate by the polymer/CO2 solution reduced the apparent weight of the plate, the density of the polymer/CO2 solution could be calculated by subtracting the true weight of the plate from its measured weight. Experimental results showed that the density of PE/CO2 solution increased with the increase of CO2 pressure and the density of PEG/CO2 solution decreased with the increase of CO2 pressure. To differentiate the effect of CO2 dissolution in polymer from that of mechanical pressure, the density of polymer/CO2 solution was compared with the density of neat polymer under the given mechanical pressure, which was calculated using the Sanchez–Lacombe equation of state and Pressure–Volume–Temperature data of the polymer. The comparison could elucidate that the dissolution of CO2 in polymer reduced density of both PEG/CO2 and PE/CO2 systems but the degree of CO2 induced‐density reduction was different between two polymer/CO2 systems. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007
Plasma membrane‐microfilament interaction in animal cells
Authors: Carraway Kermit L. , Carraway Coralie A. Carothers
Published: May 2007

Microfilament interactions with the plasma membranes of animal cells appear to vary with cell type and localization. In the erythrocyte, actin oligomers are associated with the membrane via spectrin and ankyrin. The ends of stress fibers in cultured cells, such as fibroblasts, are attached to the plasma membrane at focal adhesion sites and may involve the protein vinculin as a linking protein. In intestinal brush border microvilli a 110,000 dalton protein links the microfilament bundles to sites on the microvillus. A transmembrane complex containing actin stably associated with a cell surface glycoprotein can be isolated from ascites tumor cell microvilli and can be obtained still associated with microfilaments by gentle extraction and gradient centrifugation of the microvilli. These varied interaction mechanisms are believed to be needed to satisfy the different structural and dynamic requirements of the particular systems.
What the papers say: A molecular theme for homoeotic genes
Authors: Akam Michael
Published: May 2007

Homoeotic mutations alter the pattern of development by causing one body part to develop as some other. Among the genes identified by homoeotic mutations in Drosophila are some whose products appear to control development. A number of these have now been shown to share a common protein coding domain, which carries a sequence motif characteristic of DNA binding proteins. This protein coding domain is highly conserved in a wide range of animal taxa, including vertebrates.
The Ras pathway and spindle assembly collide?
Authors: Segal Marisa , Clarke Duncan J.
Published: May 2007

Although alterations in Ras signalling are found in about 30% of human cancers, the transforming activity of oncogenic Ras is not fully understood. In a recent paper, a putative Ras1 effector in S. pombe, named Scd1, was reported to localize to mitotic apindies. Scd1 physically associates with Moe1, a factor that may contribute to the inherent inatability of microtubules (MTs) and appears to be needed for proper apindle function. Altered MT dynamics within the spindle are likely to affect spindle assembly and chromosome capture, processes that need to be delicately controlled if cells are to guard against genome instability adn transformation. BloEssays 23: 307‐310,2001.©2001 John Willey & Sons, Inc.