bluuebunny/crossref_metadata_2025_split huggingface dataset:
Novelmad2Alleles Isolated in aSchizosaccharomyces pombeγ-Tubulin Mutant Are Defective in Metaphase Arrest Activity, but Remain Functional for Chromosome Stability in Unperturbed Mitosis
Authors: Tange Yoshie , Niwa Osami 
Published: February 2007

AbstractA previously isolated fission yeast γ-tubulin mutant containing apparently stabilized microtubules proliferated at an approximately identical rate as wild type, yet the mutant mitosis spindle dynamics were aberrant, particularly the kinetochore microtubule dynamics. Progression through mitosis in the mutant, however, resulted in mostly accurate chromosome segregation. In the absence of the spindle assembly checkpoint gene, mad2+, the spindle dynamics in the γ-tubulin mutant were greatly compromised, leading to a high incidence of chromosome missegregation. Unlike in wild-type cells, green fluorescent protein (GFP)-tagged Mad2 protein often accumulated near one of the poles of an elongating spindle in the γ-tubulin mutant. We isolated novel mad2 mutants that were defective in arresting mitotic progression upon gross perturbation of the spindle formation but remained functional for the viability of the γ-tubulin mutant. Further, the mad2 mutations did not appreciably destabilize minichromosomes in unperturbed mitoses. When overexpressed ectopically, these mutant Mad2 proteins sequestered wild-type Mad2, preventing its function in mitotic checkpoint arrest, but not in minichromosome stability. These results indicated that the Mad2 functions required for checkpoint arrest and chromosome stability in unperturbed mitosis are genetically discernible. Immunoprecipitation studies demonstrated that GFP-fused mutant Mad2 proteins formed a Mad1-containing complex with altered stability compared to that formed with wild-type Mad2, providing clues to the novel mad2 mutant phenotype.
Role of themod(mdg4)Common Region in Homolog Segregation in Drosophila Male Meiosis
Authors: Soltani-Bejnood Morvarid , Thomas Sharon E , Villeneuve Louisa , Schwartz Kierstyn , Hong Chia-sin , McKee Bruce D 
Published: February 2007

AbstractHomologous chromosomes must pair and establish stable connections during prophase I of meiosis to segregate reliably from each other at anaphase I. In most organisms, the stable connections, called chiasmata, arise from crossovers. In Drosophila males, homologs pair and segregate without crossing over. Chiasmata are replaced by a homolog conjunction complex that includes the Stromalin in Meiosis (SNM) and Modifier of Mdg4 in Meiosis (MNM) proteins. MNM is one of 31 alternative splice products of mod(mdg4), all of which share a common 402-amino-acid N terminus and differ at their C termini. Previous data demonstrated that an MNM-specific exon is required for homolog conjunction, but did not address whether the N-terminal common region, which includes a BTB domain that can mediate coalescence of protein-DNA complexes, is also required. Here we describe a mutation in the common region of mod(mdg4), Z3-3401, that causes qualitatively similar phenotypes as the MNM-specific alleles but disrupts X–Y segregation much more drastically than autosomal segregation. The mutant MNM protein in Z3-3401 is expressed throughout prophase I in spermatocytes but the protein is confined to the cytoplasm, suggesting that the Z3-3401 mutation disrupts a signal required for nuclear localization or retention. Z3-3401 fails to complement a large battery of lethal and semilethal alleles in the common region for meiotic nondisjunction, including an allele containing an amino acid substitution at a conserved residue in the BTB/POZ domain, consistent with a general requirement for the mod(mdg4) common region in homolog segregation.
Rampant Gene Exchange Across a Strong Reproductive Barrier Between the Annual Sunflowers,Helianthus annuusandH. petiolaris
Authors: Yatabe Yoko , Kane Nolan C , Scotti-Saintagne Caroline , Rieseberg Loren H 
Published: February 2007

AbstractPlant species may remain morphologically distinct despite gene exchange with congeners, yet little is known about the genomewide pattern of introgression among species. Here we analyze the effects of persistent gene flow on genomic differentiation between the sympatric sunflower species Helianthus annuus and H. petiolaris. While the species are strongly isolated in testcrosses, genetic distances at 108 microsatellite loci and 14 sequenced genes are highly variable and much lower (on average) than for more closely related but historically allopatric congeners. Our analyses failed to detect a positive association between levels of genetic differentiation and chromosomal rearrangements (as reported in a prior publication) or proximity to QTL for morphological differences or hybrid sterility. However, a significant increase in differentiation was observed for markers within 5 cM of chromosomal breakpoints. Together, these results suggest that islands of differentiation between these two species are small, except in areas of low recombination. Furthermore, only microsatellites associated with ESTs were identified as outlier loci in tests for selection, which might indicate that the ESTs themselves are the targets of selection rather than linked genes (or that coding regions are not randomly distributed). In general, these results indicate that even strong and genetically complex reproductive barriers cannot prevent widespread introgression.
A Balance Between Two Nuclear Localization Sequences and a Nuclear Export Sequence Governs Extradenticle Subcellular Localization
Authors: Stevens Katherine E , Mann Richard S 
Published: February 2007

Abstract
During animal development, transcription factor activities are modulated by several means, including subcellular localization. The Hox cofactor Extradenticle (Exd) has a dynamic subcellular localization, such that Exd is cytoplasmic by default, but is nuclear when complexed with another homeodomain protein, Homothorax (Hth). These observations raise the question of whether dimerization with Hth simply induces Exd's nuclear localization or, alternatively, if Hth is also necessary for Exd activity. To address this question, we analyzed the nuclear transport signals in Exd, including a divergent nuclear export signal (NES) and two nuclear localization signals (NLSs). We show that, although these signals are weak compared to canonical signals, they balance each other in Exd. We also provide evidence that Exd contains an NLS mask that contributes to its cytoplasmic localization. With these signals characterized, we generated forms of Exd that are nuclear localized in the absence of Hth. Surprisingly, although these Exd forms are functional, they do not phenocopy Hth overexpression. These findings suggest that Hth is required for Exd activity, not simply for inducing its nuclear localization.
Evolutionary Framework for Protein Sequence Evolution and Gene Pleiotropy
Authors: Gu Xun 
Published: February 2007

AbstractIn this article, we develop an evolutionary model for protein sequence evolution. Gene pleiotropy is characterized by K distinct but correlated components (molecular phenotypes) that affect the organismal fitness. These K molecular phenotypes are under stabilizing selection with microadaptation (SM) due to random optima shifts, the SM model. Random coding mutations generate a correlated distribution of K molecular phenotypes. Under this SM model, we further develop a statistical method to estimate the “effective” number of molecular phenotypes (Ke) of the gene. Therefore, for the first time we can empirically evaluate gene pleiotropy from the protein sequence analysis. Case studies of vertebrate proteins indicate that Ke is typically ∼6–9. We demonstrate that the newly developed SM model of protein evolution may provide a basis for exploring genomic evolution and correlations.
Prospects for Association Mapping in Classical Inbred Mouse Strains
Authors: Payseur Bret A , Place Michael 
Published: February 2007

AbstractThe collection of classical inbred mouse strains displays heritable variation in a large number of complex traits. Many generations of historical recombination have contributed to the panel of classical strain genomes, raising the possibility that quantitative trait loci could be located with high resolution by correlating strain genotypes and phenotypes. Although this association mapping framework has been successful in several empirical applications, its expected performance remains unclear. We used computer simulations based on a publicly available, dense single-nucleotide polymorphism (SNP) map to measure the power and false-positive rate of association mapping on a genomic scale across 30 commonly used classical inbred strains. Expected power is (i) often low for phenotypic effect sizes that are realistic for complex traits, (ii) highly variable across the genome, and (iii) correlated with linkage disequilibrium, aspects of the allele frequency distribution, and haplotype characteristics, as predicted by theory. Simulations also demonstrate clear potential for spurious associations to be generated by unequal relatedness among the strains. These findings suggest that association mapping in the classical strains is best applied in combination with other procedures, such as QTL mapping.
Diversity in Mating Behavior of Hermaphroditic and Male–Female Caenorhabditis Nematodes
Authors: Garcia L Rene , LeBoeuf Brigitte , Koo Pamela 
Published: February 2007

Abstract
In this study, we addressed why Caenorhabditis elegans males are inefficient at fertilizing their hermaphrodites. During copulation, hermaphrodites generally move away from males before they become impregnated. C. elegans hermaphrodites reproduce by internal self-fertilization, so that copulation with males is not required for species propagation. The hermaphroditic mode of reproduction could potentially relax selection for genes that optimize male mating behavior. We examined males from hermaphroditic and gonochoristic (male–female copulation) Caenorhabditis species to determine if they use different sensory and motor mechanisms to control their mating behavior. Instead, we found through laser ablation analysis and behavioral observations that hermaphroditic C. briggsae and gonochoristic C. remanei and Caenorhabditis species 4, PB2801 males produce a factor that immobilizes females during copulation. This factor also stimulates the vulval slit to widen, so that the male copulatory spicules can easily insert. C. elegans and C. briggsae hermaphrodites are not affected by this factor. We suggest that sensory and motor execution of mating behavior have not significantly changed among males of different Caenorhabditis species; however, during the evolution of internal self-fertilization, hermaphrodites have lost the ability to respond to the male soporific-inducing factor.
Simulated Effects of Recruitment Variability, Exploitation, and Reduced Habitat Area on the Muskellunge Population in Shoepack Lake, Voyageurs National Park, Minnesota
Authors: Frohnauer Nick K. , Pierce Clay L. , Kallemeyn Larry W. 
Published: February 2007

Abstract
The genetically unique population of muskellunge Esox masquinongy inhabiting Shoepack Lake in Voyageurs National Park, Minnesota, is potentially at risk for loss of genetic variability and long-term viability. Shoepack Lake has been subject to dramatic surface area changes from the construction of an outlet dam by beavers Castor canadensis and its subsequent failure. We simulated the long-term dynamics of this population in response to recruitment variation, increased exploitation, and reduced habitat area. We then estimated the effective population size of the simulated population and evaluated potential threats to long-term viability, based on which we recommend management actions to help preserve the long-term viability of the population. Simulations based on the population size and habitat area at the beginning of a companion study resulted in an effective population size that was generally above the threshold level for risk of loss of genetic variability, except when fishing mortality was increased. Simulations based on the reduced habitat area after the beaver dam failure and our assumption of a proportional reduction in population size resulted in an effective population size that was generally below the threshold level for risk of loss of genetic variability. Our results identified two potential threats to the long-term viability of the Shoepack Lake muskellunge population, reduction in habitat area and exploitation. Increased exploitation can be prevented through traditional fishery management approaches such as the adoption of no-kill, barbless hook, and limited entry regulations. Maintenance of the greatest possible habitat area and prevention of future habitat area reductions will require maintenance of the outlet dam built by beavers. Our study should enhance the long-term viability of the Shoepack Lake muskellunge population and illustrates a useful approach for other unique populations.
Gulf Sturgeon Movements in the Pearl River Drainage and the Mississippi Sound
Authors: Rogillio Howard E. , Ruth Ronald T. , Behrens Elizabeth H. , Doolittle Cedric N. , Granger Whitney J. , Kirk James P. 
Published: February 2007

Abstract
A study of the seasonal movements of Gulf sturgeon Acipenser oxyrinchus desotoi was conducted in the Pearl River system and the Mississippi Sound from 2000 through 2003. We captured or recaptured, marked, and released 503 Gulf sturgeon, 98 adults being tagged with internal or external telemetry tags. Movement chronologies were generally similar to those reported in other studies. Summer habitats were found in the Pearl and Bogue Chitto rivers (Louisiana–Mississippi), and these habitats were occupied from April through November. Adults and subadults were spatially separated, the adults being concentrated in the Bogue Chitto River and the subadults in the Pearl River. Tagged adults began to leave the summer habitat during September and to arrive at the mouth of the Pearl River and the Rigolets Pass. The last departure from this location was in late November. Wintering habitat between Cat, Ship, Horn, and Petit Bois islands in the Mississippi Sound was used between November and early March. Gulf sturgeon returned to the Rigolets Pass from March through June. Despite extensive sampling and the use of multiple collection gears, no eggs, larvae, or age-0 fish were captured and Gulf sturgeon spawning sites within this system remain unknown. The identification of summer and wintering habitats is essential for critical habitat designation for this species, which is federally listed as threatened.
Interplay of PI3K and cAMP/PKA signaling, and rapamycin-hypersensitivity in TGFβ1 enhancement of FSH-stimulated steroidogenesis in rat ovarian granulosa cells
Authors: Chen Yun-Ju , Hsiao Pei-Wen , Lee Ming-Ting , Mason J Ian , Ke Ferng-Chun , Hwang Jiuan-Jiuan 
Published: February 2007

Transforming growth factor (TGF) β1 facilitates FSH-induced differentiation of rat ovarian granulosa cells. The signaling crosstalk between follicle stimulating hormone (FSH) and TGFβ receptors remains unclear. This study was to investigate the interplay of cAMP/protein kinase A (PKA) and phosphatidylinositol-3-kinase (PI3K) signaling including mammalian target of rapamycin (mTOR)C1 dependence in FSH- and TGFβ1-stimulated steroidogenesis in rat granulosa cells. To achieve this aim, inhibitors of PKA (PKAI), PI3K (wortmannin), and mTORC1 (rapamycin) were employed. PKAI and wortmannin suppressions of the FSH-increased progesterone production were partly attributed to decreased level of 3β-HSD, and their suppression of the FSH plus TGFβ1 effect was attributed to the reduction of all the three key players, steroidogenic acute regulatory (StAR) protein, P450scc, and 3β-HSD. Further, FSH activated the PI3K pathway including increased integrin-linked kinase (ILK) activity and phosphorylation of Akt(S473), mTOR(S2481), S6K(T389), and transcription factors particularly FoxO1(S256) and FoxO3a(S253), which were reduced by wortmannin treatment but not by PKAI. Interestingly, PKAI suppression of FSH-induced phosphorylation of cAMP regulatory element-binding protein (CREB(S133)) disappeared in the presence of wortmannin, suggesting that wortmannin may affect intracellular compartmentalization of signaling molecule(s).
In addition, TGFβ1 had no effect on FSH-activated CREB and PI3K signaling mediators. We further found that rapamycin reduced the TGFβ1-enhancing effect of FSH-stimulated steroidogenesis, yet it exhibited no effect on FSH action. Surprisingly, rapamycin displayed a suppressive effect at concentrations that had no effect on mTORC1 activity. Together, this study demonstrates a delicate interplay between cAMP/PKA and PI3K signaling in FSH and TGFβ1 regulation of steroidogenesis in rat granulosa cells. Furthermore, we demonstrate for the first time that TGFβ1 acts in a rapamycin-hypersensitive and mTORC1-independent manner in augmenting FSH-stimulated steroidogenesis in rat granulosa cells.
Dynamic optimization of electric arc furnace operation
Authors: MacRosty Richard D. M. , Swartz Christopher L. E. 
Published: February 2007

AbstractThe main objective of this work is the development of a computational procedure for determining optimal operating strategies for an industrial electric arc furnace (EAF). These goals are achieved by incorporating a detailed mechanistic model into a mathematical optimization framework. The model used in this work includes mass and energy balances, and contains sufficient detail to describe the melting process, chemical changes, and material and energy flows. Mathematical optimization is used to determine the optimal input trajectories based on an economic criterion; process limitations are accounted for by including them within the optimization problem as constraints. This optimization procedure considers trade‐offs between all the process inputs and processing time, so as to maximize the profit. Several case studies illustrating the use of mathematical optimization in the enhancement of process performance are given. © 2007 American Institute of Chemical Engineers AIChE J, 2007
Predicting the phase equilibria of petroleum fluids with the SAFT‐VR approach
Authors: Sun Lixin , Zhao Honggang , McCabe Clare 
Published: February 2007

AbstractThe SAFT‐VR equation of state is combined with a semi‐continuous thermodynamic approach to model several synthetic and crude oil systems. In our approach, the oil fractions are defined by a continuous distribution that is then represented as discrete pseudo‐components using the Gaussian quadrature method. The SAFT‐VR parameters for the pseudo‐components are obtained from simple linear relationships that were defined in earlier work, which allows the approach to be easily applied to undefined oil systems. Good agreement between the theoretical predictions and experimental data is obtained for bubble point pressure calculations of several gas condensates and the solubility of gases such as methane, ethane, and carbon dioxide in several crude oils. © 2007 American Institute of Chemical Engineers AIChE J, 2007
Congenital nystagmus: Randomized, controlled, double‐masked trial of memantine/gabapentin
Authors: McLean Rebecca , Proudlock Frank , Thomas Shery , Degg Chris , Gottlob Irene 
Published: February 2007

AbstractObjectiveNystagmus consists of involuntary to and fro movements of the eyes. Although studies have shown that memantine and gabapentin can reduce acquired nystagmus, no drug treatment has been systematically investigated in congenital nystagmus.MethodsWe performed a randomized, double‐masked, placebo‐controlled study investigating the effects of memantine and gabapentin on congenital nystagmus over a period of 56 days. The primary outcome measure was logarithmic minimum angle of resolution (logMAR) visual acuity; the secondary outcome measures were nystagmus intensity and foveation, subjective questionnaires about visual function (VF‐14) and social function. Analyses were by intention to treat.ResultsForty‐eight patients were included in the study. One patient in the placebo group dropped out. Patients were randomized into either a memantine group (n = 16), gabapentin group (n = 16), or placebo group (n = 15). Mean visual acuity improvements showed a significant effect between treatment groups (F = 6.2; p = 0.004, analysis of variance) with improvement in both memantine and gabapentin groups. Participants with afferent visual defects showed poorer improvements in visual acuity to medication than those with apparently normal visual systems. However, eye movement recordings showed that both nystagmus forms improved in nystagmus intensity (F = 7.7; p = 0.001) and foveation (F = 8.7; p = 0.0007). Participants subjectively reported an improvement in vision after memantine and gabapentin treatment more often than in the placebo group (p = 0.03). However, there were no significant differences between the treatment groups with visual function (VF‐14) or social function questionnaires because all groups reported improvements.InterpretationOur findings show that pharmacological agents such as memantine and gabapentin can improve visual acuity, reduce nystagmus intensity, and improve foveation in congenital nystagmus. Ann Neurol 2007
Complex aerohydrodynamic research and the effectiveness of arresting dispersed particles for barbotage‐rotation
Authors: Panov A. K. , Usmanova R. R. , Zaikov V. G. , Zaikov G. E. 
Published: February 2007

AbstractThe design of barbotage‐rotation installation with different profiles of blades of the rotator has been created on the basis of modeling method. As a result of the complex of aerohydrodynamic research in the system “gas–liquid” carried out on the barbotage‐rotation unit, certain recommendations on the improvement of the construction and operating conditions have been developed with a view to a rise in the effectiveness of dust removal. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
The Aral Sea: Recent limnological changes and their conservation significance
Authors: Williams W. D. , Aladin N. V. 
Published: February 2007

Abstract1. Limnological changes to the Aral Sea, a large saline lake in central Asia, are considered. Important changes include the decreased water‐level (c. 15 m), the recession of the shoreline (up to 120 km in places), the exposure of large areas of lake bed, the increased salinity (from c. 10 to 30 g 1−1), and the marked alteration in the nature of the lacustrine biota involving decreases in diversity and biomass and the introduction of species.2. Fish have virtually disappeared from the lake and the diversity of associated bird and wildlife communities has decreased.3. The major cause of the limnological changes is the diversion of water, mainly for agricultural purposes, from inflowing rivers (the Amu‐ and Syr‐Darya), and, to a lesser degree, species introductions.4. Limnological changes have been accompanied by changes to regional rivers and terrestrial environments, groundwaters, climate, and to agricultural productivity.5. It is concluded that four major values of the lake (economic, cultural, scientific, and environmental) have been seriously diminished by recent changes to it. The need to continue limnological studies is stressed.