bluuebunny/crossref_metadata_2025 huggingface dataset:
Designing of railway wheels. Part 1: Finite element method
Authors: Sitarz M , Sladkowski A , Bizoń K , Chruzik K
Published: July 2005

Current design processes can be simplified and accelerated if computer simulation based on finite element method (FEM) is used. FEM numerical calculations of different wheels of railway wheelsets are investigated in the Department of Railway Engineering. The justification for undertaking this issue is that there is no methodology in the design of railway wheelsets both in Poland and abroad; there is no possibility of optimizing wheelsets' construction characteristics depending on manufacturing process and service parameters. The analysis of this problem has made possible:

(a) comparison of software used so far in strain calculation of railway wheelsets;

(b) elaboration of design methodology for railway wheelsets;

(c) increase in durability of railway wheelsets;

(d) increase in the safety of rail transport;

(e) decrease in manufacturing and service costs of railway wheelsets.
Mid-frequency sensorineural hearing loss: aetiology and prognosis
Authors: Shah R K , Blevins N H , Karmody C S
Published: July 2005

Objectives: An audiometric finding of mid-frequency sensorineural hearing loss (MFSNHL), or a U-shaped pattern, is uncommon. The objective of this study is to investigate the aetiology and prognostic significance of MFSNHL.

Design: Tertiary academic referral centre-based retrospective case review and review of audiograms to determine the prevalence of this audiometric finding.

Methods: Patients with a pure tone threshold average at 1, 2, and 4 kHz at least 10 dB greater than the average at 0.5 and 8 kHz were included in this study; 35 patients met these criteria. The mean age of the patients was 34.6 years old (range 4–71 years). Twelve patients (33 per cent) were under 18 years of age. Serial audiograms were obtained for 14 patients. The notes were reviewed for any pertinent otologic history, subsequent diagnoses, management and disease course.

Results: The prevalence of MFSNHL in this practice setting is less than 1 per cent. The average hearing threshold in the mid-frequencies was 44 dB, which was 17 dB and 20 dB lower than at 0.5 Hz and 8 kHz, respectively. The pure tone average (0.5, 1, 2 kHz) was 40 dB. Sixteen patients (44 per cent) required amplification. Of all patients, 22 had hereditary hearing loss, eight had idiopathic hearing loss, and five adults had vestibular schwannomas.

Conclusions: MFSNHL is an infrequent audiometric finding. The great majority of these cases are of presumed hereditary or idiopathic aetiology, although 22 per cent of adults had vestibular schwannomas. This series presents the causes and prognosis of this audiometric pattern.
Efalizumab for the Treatment of Moderate to Severe Plaque Psoriasis
Authors: Jordan Joseph K
Published: July 2005

OBJECTIVE:

To review the pharmacology, efficacy, and safety of efalizumab for the treatment of moderate to severe plaque psoriasis.

DATA SOURCES:

A MEDLINE search (1966–May 2005%) using the key words hu1124, anti-CD11a, efalizumab, Raptiva, Xanelim, and psoriasis was conducted. References of identified articles were reviewed for additional citations.

STUDY SELECTION AND DATA EXTRACTION:

Clinical trials evaluating the pharmacology, efficacy, and safety of efalizumab for treatment of moderate to severe plaque psoriasis in adults were included in our review.

DATA SYNTHESIS:

Efalizumab's ability to inhibit the binding of CD11a, a subunit of leukocyte function–associated antigen type 1, to intracellular adhesion molecule 1 results in decreased T-cell activation and migration, 2 key steps in the immunopathogenesis of psoriasis. Results of clinical trials have demonstrated that efalizumab administered subcutaneously is a safe and effective treatment for moderate to severe plaque psoriasis. Efalizumab was well tolerated in trials, with the majority of adverse events arising with the first dose and decreasing with subsequent doses. The high cost of this agent and lack of head-to-head trials with other drugs will likely restrict its use to patients who have failed prior systemic therapy or phototherapy.

CONCLUSIONS:

Efalizumab is a safe and effective therapy for treatment of moderate to severe plaque psoriasis in patients who have failed prior systemic therapy or phototherapy.
The Agony and the Ecstasy: Charlton Heston and the Screen Actors Guild
Authors: Raymond Emilie
Published: July 2005

Charlton Heston, one of Hollywood's most prominent political activists, devoted much of his time to the Screen Actors Guild. Throughout the course of Heston's long acting career, the guild shifted its policy emphasis on several occasions. During the 1960s, when Heston served on the executive board, the guild adhered to its traditional strategy of focusing on wages, benefits, and working conditions. At that point, Heston took a moderate approach toward guild business, often showing his willingness to compromise. In the 1970s, the guild leadership was captured by more “liberal” actors who wished to expand the union's activities into social and political channels not directly related to the job of acting. In the 1980s, the guild's leadership became even more militantly liberal. The resulting policy shifts provoked a reaction from Heston and a number of other conservative actors. It quickly became evident that Heston was no longer willing to compromise; he began to take an ideological, hard-line approach to guild matters. He not only led the conservatives in a successful campaign to return the guild to its original policy focus, but he also shaped federal labor policy with his efforts. Convinced that safety mechanisms were needed to protect guild members from a politically active board in the future, Heston advocated federal policies that would allow union members to withhold part of their dues if they disagreed with the political activities undertaken by union leadership.
The Electric Lighthouse in the Nineteenth Century: Aid to Navigation and Political Technology
Authors: Schiffer Michael B
Published: July 2005

Beginning in 1859, the lighthouse was the site of the first commercial application of generator-powered electric-arc lighting. At the end of the century, however, only about thirty had been installed among thousands of lighthouses worldwide. In seeking to explain the differential adoption of the technology, this paper compares the performance characteristics of electric lights and its competitor, oil lamps. Although the electric arc was at a disadvantage in utilitarian performance characteristics, such as costs of installation and maintenance, it was an adequate light under most conditions and excelled in haze and light fog; it could also uniquely symbolize a nation's command of cutting-edge electrical science and technology. Most nations, favoring utilitarian performance characteristics in their decisions, adopted no electric lights. In adopting nations, especially France and England, symbolic performance was heavily weighted, for the electric light was both an aid to navigation and a political technology.
Synapse-Specific Regulation of AMPA Receptor Subunit Composition by Activity
Authors: Harms Kimberly J. , Tovar Kenneth R. , Craig Ann Marie
Published: July 2005

We examined the changes that arise when neurotransmitter release is inhibited in a subpopulation of hippocampal neurons in coculture with normally active neighbors. Subsets of neurons were presynaptically silenced by chronic expression of tetanus toxin light chain tagged with cyan fluorescent protein (TNTCFP). Surprisingly, silenced neurons formed as many presynaptic terminals as their active neighbors when grown together on glial microislands. However, silenced neurons could not recruit the AMPA-type glutamate receptor subunit GluR1 as efficiently when competing with active neighbors. The immunofluorescence intensity ratio of GluR1 at synaptic puncta versus shaft was reduced by 22% opposite TNTCFP-expressing terminals compared with active neighbors. In contrast, this effect is abolished when vesicular release is blocked in all neurons. Local presynaptic inhibition by TNTCFP did not change the synaptic level of the AMPA receptor subunits GluR2 or GluR2/3 or of the PSD95 (postsynaptic density 95) family scaffolding proteins. Thus, neurotransmitter release selectively regulates the AMPA receptor population on a synapse-by-synapse basis but is not essential for an axon to efficiently compete for synaptic territory in a simple model system. These results demonstrate precise input specificity of postsynaptic receptor composition via differential activity among neighbor synapses.
Dual Presynaptic Control by ATP of Glutamate Release via Facilitatory P2X1, P2X2/3, and P2X3and Inhibitory P2Y1, P2Y2, and/or P2Y4Receptors in the Rat Hippocampus
Authors: Rodrigues Ricardo J. , Almeida Teresa , Richardson Peter J. , Oliveira Catarina R. , Cunha Rodrigo A.
Published: July 2005

ATP is released in a vesicular manner from nerve terminals mainly at higher stimulation frequencies. There is a robust expression of ATP (P2) receptors in the brain, but their role is primarily unknown. We report that ATP analogs biphasically modulate the evoked release of glutamate from purified nerve terminals of the rat hippocampus, the facilitation being mediated by P2X1, P2X2/3, and P2X3[antagonized by 8-(benzamido)naphthalene-1,3,5-trisulfonate and 2′,3′-O-(2,4,6-trinitrophenyl)-ATP] and the inhibition by P2Y1,P2Y2, and/or P2Y4[antagonized by reactive blue 2 and 2′deoxy-N6-methyladenosine-3′,5′-bisphosphate and mimicked by P1-(urinine 5′-),P4-(inosine 5′-) tetraphosphate and 2-methylthio-ADP] receptors. The combination of single-cell PCR analysis of rat hippocampal pyramidal neurons, Western blot analysis of purified presynaptic active zone fraction, and immunocytochemical analysis of hippocampal glutamatergic terminals revealed that the P2 receptors expressed in glutamatergic neurons, located in the active zone and in glutamatergic terminals, were precisely P2X1,P2X2, and P2X3subunits and P2Y1,P2Y2, and P2Y4receptors. This provides coincident functional and molecular evidence that P2 receptors are present and act presynaptically as a modulatory system controlling hippocampal glutamate release.
Intracortical Origins of Interocular Suppression in the Visual Cortex
Authors: Sengpiel Frank , Vorobyov Vasily
Published: July 2005

The response of neurons in the primary visual cortex to an optimally oriented grating is usually suppressed quite dramatically when a second grating of, for example, orthogonal orientation is superimposed. Such “cross-orientation suppression” has been implicated in the generation of cortical orientation selectivity and local response normalization. Until recently, little experimental evidence was available concerning the neurophysiological substrate of this phenomenon, although an involvement of intracortical inhibition was commonly assumed. However, Freeman et al. (2002) proposed that cortical cross-orientation suppression is caused by suppression in the thalamus and depression at geniculocortical synapses. Here, we examine a dichoptic form of cross-orientation suppression, termed interocular suppression and thought to be involved in binocular rivalry (Sengpiel et al., 1995a). We show that its dependency on the drift rate of the suppressing stimulus is consistent with a cortical origin; unlike monocular cross-orientation suppression, it cannot be evoked by very fast-moving stimuli. Moreover, we find that previous adaptation to the orthogonal stimulus essentially eliminates interocular suppression. Because adaptation is a cortical phenomenon, this result also argues in favor of a cortical locus of suppression, again unlike monocular cross-orientation suppression, which is not affected by adaptation to the suppressor (Freeman et al., 2002). Finally, interocular suppression is greatly reduced in the presence of the GABA antagonist bicuculline. Together, our study demonstrates that interocular suppression is substantially different from monocular cross-orientation suppression and is mediated by inhibitory circuitry within the visual cortex.
Cystine/Glutamate Exchange Regulates Metabotropic Glutamate Receptor Presynaptic Inhibition of Excitatory Transmission and Vulnerability to Cocaine Seeking
Authors: Moran Megan M. , McFarland Krista , Melendez Roberto I. , Kalivas Peter W. , Seamans Jeremy K.
Published: July 2005

Withdrawal from chronic cocaine reduces extracellular glutamate levels in the nucleus accumbens by decreasing cystine/glutamate exchange (xc-). Activating xc- withN-acetylcysteine restores extracellular glutamate and prevents cocaine-induced drug seeking. It was hypothesized that the activation of xc- prevents drug seeking by increasing glutamatergic tone on presynaptic group II metabotropic glutamate receptors (mGluR2/3) and thereby inhibiting excitatory transmission. In the first experiment, the capacity of glutamate derived from xc- to regulate excitatory transmission via mGluR2/3 was determined. Physiological levels of cystine (100-300 nm) were restored to acute tissue slices from the nucleus accumbens or prefrontal cortex. Cystine increased glutamate efflux and decreased miniature EPSC (mEPSC) and spontaneous EPSC (sEPSC) frequency as well as evoked EPSC amplitude. These effects of cystine were presynaptic, because there was no change in mEPSC or sEPSC amplitude, and an increase in the evoked EPSC paired-pulse facilitation ratio. The cystine-induced reduction in EPSCs was reversed by blocking either xc- or mGluR2/3. In the second experiment, blocking mGluR2/3 prevented the ability ofN-acetylcystine to inhibit the reinstatement of drug seeking in rats trained to self-administer cocaine. These data demonstrate that nonsynaptic glutamate derived from xc- modulates synaptic glutamate release and thereby regulates cocaine-induced drug seeking.
Reducing Cerebral Microvascular Amyloid-β Protein Deposition Diminishes Regional Neuroinflammation in Vasculotropic Mutant Amyloid Precursor Protein Transgenic Mice
Authors: Miao Jianting , Vitek Michael P. , Xu Feng , Previti Mary Lou , Davis Judianne , Van Nostrand William E.
Published: July 2005

Cerebral microvascular amyloid-β (Aβ) protein deposition is emerging as an important contributory factor to neuroinflammation and dementia in Alzheimer's disease and related familial cerebral amyloid angiopathy disorders. In particular, cerebral microvascular amyloid deposition, but not parenchymal amyloid, is more often correlated with dementia. Recently, we generated transgenic mice (Tg-SwDI) expressing the vasculotropic Dutch (E693Q)/Iowa (D694N) mutant human Aβ precursor protein in brain that accumulate abundant cerebral microvascular fibrillar amyloid deposits. In the present study, our aim was to assess how the presence or absence of fibrillar Aβ deposition in the cerebral microvasculature affects neuroinflammation inTg-SwDImice. UsingTg-SwDImice bred onto an apolipoprotein E gene knock-out background, we found a strong reduction of fibrillar cerebral microvascular Aβ deposition, which was accompanied by a sharp decrease in microvascular-associated neuroinflammatory cells and interleukin-1β levels. Quantitative immunochemical measurements showed that this reduction of the neuroinflammation occurred in the absence of lowering the levels of total Aβ40/Aβ42 or soluble Aβ oligomers in brain. These findings suggest that specifically reducing cerebral microvascular fibrillar Aβ deposition, in the absence of lowering either the total amount of Aβ or soluble Aβ oligomers in brain, may be sufficient to ameliorate microvascular amyloid-associated neuroinflammation.
Cooperative Activation of D1and D2Dopamine Receptors Enhances a Hyperpolarization-Activated Inward Current in Layer I Interneurons
Authors: Wu JianPing , Hablitz John J.
Published: July 2005

Layer I of the neocortex comprises axonal processes from widespread regions of the brain and a unique population of GABAergic interneurons. Dopamine is known to directly depolarize layer I interneurons, but the underlying mechanism is unclear. Using whole-cell recording techniques in neocortical brain slices, we have examined how dopamine increases excitability of layer I interneurons in postnatal day 7-11 rats. Dopamine (30 μm) caused a 10 mV depolarization of layer I neurons. Paradoxically, neither the D1-like receptor agonist 6-chloro-2,3,4,5-tetrahydro-1-phenyl-1H-3-benzazepine hydrobromide (SKF81297) (1-10 μm) nor the D2-like agonist quinpirole (10 μm) produced a significant depolarization. Depolarization was observed whenSKF81297and quinpirole were coapplied. When G-protein βγ subunits were included in the recording pipette, D1but not D2agonists depolarized layer I neurons. Bath application of 4-ethylphenylamino-1,2-dimethyl-6-methylaminopyrimidinium chloride, a specific blocker of inwardly rectifying hyperpolarization-activated current (Ih) channels, hyperpolarized the neurons and occluded the action of dopamine. Voltage-clamp analysis demonstrated that dopamine increased the amplitude and shifted the voltage dependence of activation ofIh. These results indicate thatIhcontributes to the resting potential of layer I interneurons and is subject to modulation by dopamine.
Gap-Junctional Coupling between Neurogliaform Cells and Various Interneuron Types in the Neocortex
Authors: Simon Anna , Oláh Szabolcs , Molnár Gábor , Szabadics János , Tamás Gábor
Published: July 2005

Electrical synapses contribute to the generation of synchronous activity in neuronal networks. Several types of cortical GABAergic neurons acting via postsynaptic GABAAreceptors also form electrical synapses with interneurons of the same class, suggesting that synchronization through gap junctions could be limited to homogenous interneuron populations. Neurogliaform cells elicit combined GABAAand GABABreceptor-mediated postsynaptic responses in cortical pyramidal cells, but it is not clear whether neurogliaform cells are involved in networks linked by electrical coupling.

We recorded from pairs, triplets, and quadruplets of cortical neurons in layers 2 and 3 of rat somatosensory cortex (postnatal day 20-35). Neurogliaform cells eliciting slow IPSPs on pyramidal cells also triggered divergent electrical coupling potentials on interneurons. Neurogliaform cells were electrically coupled to other neurogliaform cells, basket cells, regular-spiking nonpyramidal cells, to an axoaxonic cell, and to various unclassified interneurons showing diverse firing patterns and morphology. Electrical interactions were mediated by one or two electron microscopically verified gap junctions linking the somatodendritic domain of the coupled cells.

Our results suggest that neurogliaform cells have a unique position in the cortical circuit. Apart from eliciting combined GABAAand GABABreceptor-mediated inhibition on pyramidal cells, neurogliaform cells establish electrical synapses and link multiple networks formed by gap junctions restricted to a particular class of interneuron. Widespread electrical connections might enable neurogliaform cells to monitor the activity of different interneurons acting on GABAAreceptors at various regions of target cells.
Off-Line Learning and the Primary Motor Cortex
Authors: Robertson Edwin M. , Press Daniel Z. , Pascual-Leone Alvaro
Published: July 2005

We are all familiar with acquiring skills during practice, but skill can also continue to develop between practice sessions. These “off-line” improvements are frequently supported by sleep, but they can be time dependent when a skill is acquired unintentionally. The magnitude of these over-day and overnight improvements is similar, suggesting that a similar mechanism may support both types of off-line improvements. However, here we show that disruption of the primary motor cortex with repetitive transcranial magnetic stimulation blocks off-line improvements over the day but not overnight. This suggests that a memory may be rescued overnight and subsequently enhanced or that different aspects of a skill, with differential dependencies on the primary motor cortex, are enhanced over day and overnight. Off-line improvements of similar magnitude are not supported by similar mechanisms; instead, the mechanisms engaged may depend on brain state.
Central and Sensory Contributions to the Activation and Organization of Muscle Synergies during Natural Motor Behaviors
Authors: Cheung Vincent C. K. , d'Avella Andrea , Tresch Matthew C. , Bizzi Emilio
Published: July 2005

Previous studies have suggested that the motor system may simplify control by combining a small number of muscle synergies represented as activation profiles across a set of muscles. The role of sensory feedback in the activation and organization of synergies has remained an open question. Here, we assess to what extent the motor system relies on centrally organized synergies activated by spinal and/or supraspinal commands to generate motor outputs by analyzing electromyographic (EMG) signals collected from 13 hindlimb muscles of the bullfrog during swimming and jumping, before and after deafferentation. We first established that, for both behaviors, the intact and deafferented data sets possess low and similar dimensionalities. Subsequently, we used a novel reformulation of the non-negative matrix factorization algorithm to simultaneously search for synergies shared by, and synergies specific to, the intact and deafferented data sets. Most muscle synergies were identified as shared synergies, suggesting that EMGs of locomotor behaviors are generated primarily by centrally organized synergies. Both the amplitude and temporal patterns of the activation coefficients of most shared synergies, however, were altered by deafferentation, suggesting that sensory inflow modulates activation of those centrally organized synergies. For most synergies, effects of deafferentation on the activation coefficients were not consistent across frogs, indicating substantial interanimal variability of feedback actions. We speculate that sensory feedback might adapt recruitment of muscle synergies to behavioral constraints, and the few synergies specific to the intact or deafferented states might represent afferent-specific modules or feedback reorganization of spinal neuronal networks.
A Variant C178T in the Regulatory Region of the Serotonin Receptor GeneHTR3AModulates Neural Activation in the Human Amygdala
Authors: Iidaka Tetsuya , Ozaki Norio , Matsumoto Atsushi , Nogawa Junpei , Kinoshita Yoko , Suzuki Tatsuyo , Iwata Nakao , Yamamoto Yukiko , Okada Tomohisa , Sadato Norihiro
Published: July 2005

Converging evidence in neurophysiological and neuroimaging studies has suggested that the limbic and prefrontal systems play important roles in emotion and cognition. These structures are activated when we see a human face, assuming that we automatically evaluate the biological significance of the stimuli. The serotonin (5-HT) system within the brain has been tied to various behaviors such as mood and anxiety and to the biology of neuropsychiatric disorders. To investigate the link between the 5-HT system and limbic/prefrontal activity, normal subjects (n= 26) who underwent functional magnetic resonance imaging and faced recognition tasks were genotyped for the single nucleotide polymorphism C178T in the regulatory region of the serotonin receptor type 3 gene (HTR3A). We found that the subjects with C/C alleles had greater activity in the amygdala and dorsal and medial prefrontal cortices than those with C/T alleles. The C/C group also showed a faster reaction time during the task than the C/T group. The temperamental predisposition of the subjects had a significant correlation with brain activity in the C/C group. The genotype effect in the right amygdala and prefrontal cortex was largest during the first run of the experiment. These results indicate that the C178T variation in theHTR3Ahas a critical influence on the amygdaloid activity and on human face processing, probably through regulation of the receptor expression. The present study may contribute to elucidating a possible link among genes, the brain, and behavior in normal populations and may help reveal the biological basis of neuropsychiatric disorders.
Two Hybridization Events Define the Population Structure of Trypanosoma cruzi
Authors: Westenberger Scott J , Barnabé Christian , Campbell David A , Sturm Nancy R
Published: July 2005

Genetic variation in Trypanosoma cruzi is likely a key determinant in transmission and pathogenesis of Chagas disease. We have examined nine loci as markers for the extant T. cruzi strains. Four distinct alleles were found for each locus, corresponding to the sequence classes present in the homozygous discrete typing units (DTUs) I, IIa, IIb, and IIc. The alleles in DTUs IIa and IIc showed a spectrum of polymorphism ranging from DTU I-like to DTU IIb-like, in addition to DTU-specific sequence variation. DTUs IId and IIe were indistinguishable, showing DTU homozygosity at one locus and heterozygosity with DTU IIb and IIc allelic sequences at eight loci. Recombination between the DTU IIb and IIc alleles is evidenced from mosaic polymorphisms. These data imply that two discrete hybridization events resulted in the formation of the current DTUs. We propose a model in which a fusion between ancestral DTU I and IIb strains gave rise to a heterozygous hybrid that homogenized its genome to become the homozygous progenitor of DTUs IIa and IIc. The second hybridization between DTU IIb and IIc strains that generated DTUs IId and IIe resulted in extensive heterozygosity with subsequent recombination of parental genotypes.
Evolutionary Conservation of Ceratitis capitata transformer Gene Function
Authors: Pane Attilio , De Simone Annamaria , Saccone Giuseppe , Polito Catello
Published: July 2005

Transformer functions as a binary switch gene in the sex determination and sexual differentiation of Drosophila melanogaster and Ceratitis capitata, two insect species that separated nearly 100 million years ago. The TRA protein is required for female differentiation of XX individuals, while XY individuals express smaller, presumably nonfunctional TRA peptides and consequently develop into adult males. In both species, tra confers female sexual identity through a well-conserved double-sex gene. However, unlike Drosophila tra, which is regulated by the upstream Sex-lethal gene, Ceratitis tra itself is likely to control a feedback loop that ensures the maintenance of the female sexual state. The putative CcTRA protein shares a very low degree of sequence identity with the TRA proteins from Drosophila species. However, in this study we show that a female-specific Ceratitis Cctra cDNA encoding the putative full-length CcTRA protein is able to support the female somatic and germline sexual differentiation of D. melanogaster XX; tra mutant adults. Although highly divergent, CcTRA can functionally substitute for DmTRA and induce the female-specific expression of both Dmdsx and Dmfru genes. These data demonstrate the unusual plasticity of the TRA protein that retains a conserved function despite the high evolutionary rate. We suggest that transformer plays an important role in providing a molecular basis for the variety of sex-determining systems seen among insects.
Gene Expression During Drosophila Wing Morphogenesis and Differentiation
Authors: Ren Nan , Zhu Chunming , Lee Haeryun , Adler Paul N
Published: July 2005

The simple cellular composition and array of distally pointing hairs has made the Drosophila wing a favored system for studying planar polarity and the coordination of cellular and tissue level morphogenesis. We carried out a gene expression screen to identify candidate genes that functioned in wing and wing hair morphogenesis. Pupal wing RNA was isolated from tissue prior to, during, and after hair growth and used to probe Affymetrix Drosophila gene chips. We identified 435 genes whose expression changed at least fivefold during this period and 1335 whose expression changed at least twofold. As a functional validation we chose 10 genes where genetic reagents existed but where there was little or no evidence for a wing phenotype. New phenotypes were found for 9 of these genes, providing functional validation for the collection of identified genes. Among the phenotypes seen were a delay in hair initiation, defects in hair maturation, defects in cuticle formation and pigmentation, and abnormal wing hair polarity. The collection of identified genes should be a valuable data set for future studies on hair and bristle morphogenesis, cuticle synthesis, and planar polarity.
A Genetic Screen for Dominant Modifiers of a Small-Wing Phenotype in Drosophila melanogaster Identifies Proteins Involved in Splicing and Translation
Authors: Coelho Carmen M A , Kolevski Benjamin , Walker Cherryl D , Lavagi Irene , Shaw Thomas , Ebert Anselm , Leevers Sally J , Marygold Steven J
Published: July 2005

Studies in the fly, Drosophila melanogaster, have revealed that several signaling pathways are important for the regulation of growth. Among these, the insulin receptor/phosphoinositide 3-kinase (PI3K) pathway is remarkable in that it affects growth and final size without disturbing pattern formation. We have used a small-wing phenotype, generated by misexpression of kinase-dead PI3K, to screen for novel mutations that specifically disrupt organ growth in vivo. We identified several complementation groups that dominantly enhance this small-wing phenotype. Meiotic recombination in conjunction with visible markers and single-nucleotide polymorphisms (SNPs) was used to map five enhancers to single genes. Two of these, nucampholin and prp8, encode pre-mRNA splicing factors. The three other enhancers encode factors required for mRNA translation: pixie encodes the Drosophila ortholog of yeast RLI1, and RpL5 and RpL38 encode proteins of the large ribosomal subunit. Interestingly, mutations in several other ribosomal protein-encoding genes also enhance the small-wing phenotype used in the original screen. Our work has therefore identified mutations in five previously uncharacterized Drosophila genes and provides in vivo evidence that normal organ growth requires optimal regulation of both pre-mRNA splicing and mRNA translation.
Cost of Interacting With Sexual Partners in a Facultative Sexual Microbe
Authors: Xu Jianping
Published: July 2005

The widespread occurrence of sexual organisms despite the high costs of sex has long intrigued biologists. The best-known costs are the twofold cost of producing males and the cost associated with producing traits to attract mates and to interact with mating partners, such as exaggerated sexual behaviors and morphological modifications. These costs have been inferred from studies of plants and animals but are thought to be absent in facultative sexual microbes. Here, using the facultative sexual fungus Cryptococcus neoformans, I provide experimental evidence showing that: (i) interactions with active sexual partners can be costly for vegetative fitness in a facultative sexual microbe; (ii) this cost is positively correlated to mating ability; (iii) this cost is composed of at least two distinct components, the cost of producing mating signals that exert effects on mating partners and that associated with responding to active mating partners; and (iv) extended asexual reproduction can reduce both components of the cost. This cost must have been compensated for by the production of zygotes and sexual spores to allow the initial evolution and spread of sexual reproduction in eukaryotes.
Transcriptional Compensation for Gene Loss Plays a Minor Role in Maintaining Genetic Robustness in Saccharomyces cerevisiae
Authors: Wong Sharyl L , Roth Frederick P
Published: July 2005

If a gene is mutated and its function lost, are compensatory genes upregulated? We investigated whether genes are transcriptionally upregulated when their synthetic sick or lethal (SSL) partners are lost. We identified several new examples; however, remarkably few SSL pairs exhibited this phenomenon, suggesting that transcriptional compensation by SSL partners is a rare mechanism for maintaining genetic robustness.
Exploitation of Nile Tilapia in a Closed-System Public Fishing Reservoir in Northern Arkansas
Authors: Henry Sam D. , Barkley Sam W. , Johnson Ronald L.
Published: July 2005

Nile tilapia Oreochromis niloticus have been stocked as a forage species annually since 2001 in Lake Hogue, a 101-ha, closed-system public fishing reservoir in northeastern Arkansas. A mail-in reward tag study was implemented in 2003 to determine total estimated harvest, contribution of Nile tilapia to the lake's fishery, and impact of angler harvest on Nile tilapia reproduction. Estimates of harvest were corrected for tag loss (1.1%), tag-induced mortality (1.0%), and nonreporting of tags by anglers (53% reporting rate). Angler-hours were compared between anglers targeting Nile tilapia and those targeting other species. Anglers harvested an estimated 83% of the stocked Nile tilapia (56% of stocked fish were captured by traditional panfishing techniques; 27% were captured by use of dip nets during the winter die-off in late November). Anglers targeting primarily Nile tilapia fished significantly longer (5.7 h/angler) than individuals who incidentally caught Nile tilapia while fishing for other species (4.5 h/angler). Analysis of the economic impact of stocking Nile tilapia demonstrated a benefit-cost ratio of 0.38. Harvest of Nile tilapia did not apparently interfere with the management goal of using the fish as a forage species for game fishes. Tag return data strongly suggested that at midday during the hot summer months, when fishing pressure had traditionally been low, anglers targeted Nile tilapia in favor of the traditional target species (e.g., bluegill Lepomis macrochirus and redear sunfish L. microlophus).
Establishing a Linkage between Phosphorus Forms in Dairy Diets, Feces, and Manures
Authors: Toor Gurpal S. , Cade‐Menun Barbara J. , Sims J. Thomas
Published: July 2005

Effective manure management to efficiently utilize organic wastes without causing environmental degradation requires a clear understanding of the transformation of P forms from diet to manure. Thus, the objective of this study was to establish quantitative relationships between P forms in diets, feces, and manures collected from U.S. Northeastern and Mid‐Atlantic commercial dairy farms. Total P in diets ranged from 3.6 to 5.3 g kg−1 dry matter, while the feces had higher P than diets (5.7–9.5 g kg−1) and manures had lower P (2.5–8.9 g kg−1) than feces. The farms with total dietary P of 4.8 to 5.3 g P kg−1 had twofold higher concentrations of phytic acid (1647–2300 mg P kg−1) than farms with 3.6 to 4.0 g dietary P kg−1 (844–1100 mg P kg−1). Much of the phytic acid in diets was converted to inorganic orthophosphate in the rumen as indicated by a reduction in phytic acid percentage from diets (32%) to feces (18%). The proportion of orthophosphate diesters (phospholipids, deoxyribonucleic acid [DNA]) was twice as high in feces (6.2–10%) as diets (2.4–5.3%) suggesting the excretion of microbial residues in feces. Phosphonates (aminoethyl phosphonates and phosphonolipids) were not seen in diets but were detected in feces and persisted in manures, which suggests a microbial origin. These organic compounds (phytic acid, phospholipids, DNA) were decomposed on storage of feces in slurry pits, increasing orthophosphate in manures by 9 to 12% of total P. These results suggest that reducing dietary P and typically storing feces in dairy farms will result in manure with similar chemical forms (primarily orthophosphate: 63–77%) that will be land applied. Thus, both the reduction of dietary P and storage of manure on farm are important for controlling solubility and bioavailability of P forms in soils and waters.
Bioluminescent Bacteria as Indicators of Chemical Contamination of Coastal Waters
Authors: Frischer M. E. , Danforth J. M. , Foy T. F. , Juraske R.
Published: July 2005

The ratio of bioluminescent to total bacteria (bioluminescent ratio, BLR) as an indicator of a variety of types of anthropogenic contamination of estuarine ecosystems was evaluated through a series of laboratory and field studies. Laboratory studies indicated that the BLR of natural bacterioplankton communities was proportionally reduced in the presence of a number of contaminants including diesel fuel and saltmarsh sediments co‐contaminated with mercury and polychlorinated biphenyls (PCBs). Bioluminescent ratio inhibition was observed after short‐term exposure to a contaminant suggesting a physiological rather than a population response of native microbial communities. Simulated eutrophication did not suppress the BLR. Field observations of the BLR were conducted weekly for a 2‐yr period in the Skidaway River estuary, Georgia, USA. These observations revealed considerable seasonal variability associated with the BLR. Bioluminescent ratios were highest during the summer (25 ± 15%), lower in the fall (6 ± 5%) and spring (3 ± 2%), and near zero during the winter. Although the BLR was not significantly correlated to salinity at a single site (Skidaway River estuary), the BLR was significantly correlated with salinity when sites within the same estuary system were compared (r2 = 0.93). Variation in BLR was not correlated to standard bacteriological indicators of water quality including total and fecal coliform bacteria. Comparison of the BLR from impacted and pristine estuarine sites during the fall suggested that anthropogenically impacted sites exhibited lower BLR than predicted from salinity versus BLR relationships developed in pristine systems. These observations suggest that the BLR could be used as a simple and reliable initial indicator of chemical contamination of estuarine systems resulting from human activity.
Reductive Dechlorination of Tetrachloroethene in a Sand Reactor Using a Potentiostat
Authors: Shimomura Tatsuo , Sanford Robert A.
Published: July 2005

In this study, an electrochemical system was investigated to enhance abiotic dechlorination of chlorinated solvents in contaminated soil in situ. A potentiostatic electrolysis sand reactor was developed and tested to evaluate tetrachloroethene (PCE) dechlorination in saturated sand. When operated with recirculating nutrient‐supplemented water the reactor sustained a low oxidation reduction potential (ORP) at the cathode (<−400 mV standard hydrogen electrode [SHE]), a pH less than 9.4, and electric current >5 mA at room temperature with the cathodic potential controlled at −950 mV SHE. Tetrachloroethene in the electrolysis reactor had a half‐life of 6.8 d compared with the control bioreactor without electrolysis, which had a PCE half‐life of 16.4 d. Ethane and ethene were the main dechlorination products in the test reactor, while trichloroethene (TCE) accumulated in the nutrient‐amended control reactor without electrolysis. An electrolysis reactor operated with water not amended with nutrients showed a PCE half‐life of 7.6 d, suggesting that most of dechlorination activity in the reactor was abiotic. Since complete dechlorination can be achieved under moderate pH and temperature, this type of electrolysis technology is attractive as a remedial method for subsurface chloroethene contamination.
Sorption, Mobility, and Transformation of Estrogenic Hormones in Natural Soil
Authors: Casey Francis X. M. , Šimůnek Jiří , Lee Jaehoon , Larsen Gerald L. , Hakk Heldur
Published: July 2005

Potent estrogenic hormones are consistently detected in the environment at low concentration, yet these chemicals are strongly sorbed to soil and are labile. The objective of this research was to improve the understanding of the processes of sorption, mobility, and transformation for estrogens in natural soils, and their interaction. Equilibrium and kinetic batch sorption experiments, and a long‐term column study were used to study the fate and transport of 17β‐estradiol and its primary metabolite, estrone, in natural soil. Kinetic and equilibrium batch experiments were done using radiolabeled 17β‐estradiol and estrone. At the concentrations used, it appeared that equilibrium sorption for both estrogens was achieved between 5 and 24 h, and that the equilibrium sorption isotherms were linear. The logKocvalues for 17β‐estradiol (2.94) and estrone (2.99) were consistent with previously reported values. Additionally, it was found that there was rate‐limited sorption for both 17β‐estradiol (0.178 h−1) and estrone (0.210 h−1). An approximately 42 h long, steady‐flow, saturated column experiment was used to study the transport of radiolabeled 17β‐estradiol, which was applied in a 5.00 mg L−1solution pulse for 44 pore volumes. 17β‐estradiol and estrone were the predominant compounds detected in the effluent. The effluent breakthrough curves were asymmetric and the transport modeling indicated that sorption was rate‐limited. Sorption rates and distributions of the estrogens were in agreement between column and batch experiments. This research can provide a better link between the laboratory results and observations in the natural environment.
Accelerated Weathering of Biosolid‐Amended Copper Mine Tailings
Authors: Pond Andrew P. , White Scott A. , Milczarek Michael , Thompson Thomas L.
Published: July 2005

Application of municipal biosolids to mine tailings can enhance revegetation success, but may cause adverse environmental impacts, such as increased leaching of NO−3and metals to ground water. Kinetic weathering cells were used to simulate geochemical weathering to determine the effects of biosolid amendment on (i) pH of leachate and tailings, (ii) leaching of NO−3and SO42−, (iii) leaching and bioavailability (DTPA‐extractable) of selected metals, and (iv) changes in tailing mineralogy. Four Cu mine tailings from southern Arizona differing in initial pH (3.3–7.3) and degree of weathering were packed into triplicate weathering cells and were unamended and amended with two rates (equivalent to 134 and 200 Mg dry matter ha−1) of biosolids. Biosolid application to acid (pH 3.3) tailings resulted in pH values as high as 6.3 and leachate pH as high as 5.7, and biosolids applied to circumneutral tailings resulted in no change in tailing or leachate pH. Concentrations of NO−3–N of up to 23 mg L−1occurred in leachates from circumneutral tailings. The low pH of the acidic tailing apparently inhibited nitrification, resulting in leachate NO−3–N of <5 mg L−1Less SO42−–S was leached in biosolid‐amended versus unamended acid tailings (final rate of 0.04 compared with 0.11 g SO42−–S wk−1). Copper concentrations in leachates from acidic tailings were reduced from 53 to 27 mg L−1with biosolid amendment. Copper and As concentrations increased slightly in leachates from biosolid‐amended circumneutral tailings. Small increases in DTPA‐extractable Cu, Ni, and Zn occurred in all tailings with increased biosolid rate. Overall, there was little evidence of potential for adverse environmental impacts resulting from biosolid application to these Cu mine tailings.
Nitrate Reduction in the Presence of Wüstite
Authors: Rakshit Sudipta , Matocha Christopher J. , Haszler Gerald R.
Published: July 2005

Recent strategies to reduce elevated nitrate NO3− concentrations employ metallic Fe0 as a reductant. Secondary products of Fe0 corrosion include magnetite (Fe3O4), green rust [Fe6(OH)12SO4], and wüstite [FeO(s)]. To our knowledge, no studies have been reported on the reactivity of NO3− with FeO(s). This project was initiated to evaluate the reactivity of FeO(s) with NO3− under abiotic conditions. Stirred batch reactions were performed in an anaerobic chamber over a range of pH values (5.45, 6.45, and 7.45), initial FeO(s) concentrations (1, 5, and 10 g L−1), initial NO3− concentrations (1, 10, and 15 mM), and temperatures (3, 21, 31, and 41°C) for kinetic and thermodynamic determinations. Suspensions were periodically removed and filtered to measure dissolved nitrogen and iron species. Solid phases were characterized using X‐ray diffraction (XRD) and scanning electron microscopy (SEM). Nitrate reduction by FeO was rapid and characterized by nearly stoichiometric conversion of NO3− to NH4+ Transient NO2− formation also occurred. The XRD and SEM results indicated the formation of Fe3O4 as a reaction product of the heterogeneous redox reaction. Kinetics of NO3− reduction suggested a rate equation of the type: where k = 3.46 × 10−3 ± 0.38 × 10−3 M−1 s−1, at 25°C. Arrhenius and Eyring plots indicate that the reaction is surface chemical–controlled and proceeds by an associative mechanism involving a step where both NO3− and FeO(s) bind together in an intermediate complex.
Impact of Soil Amendments on Reducing Phosphorus Losses from Runoff in Sod
Authors: Torbert H. A. , King K. W. , Harmel R. D.
Published: July 2005

Research was initiated to study the interaction between soil amendments (lime, gypsum, and ferrous sulfate) and dissolved molybdate reactive phosphorus [RP(<0.45)] losses from manure applications from concentrated runoff flow through a sod surface. Four run‐over boxes (2.2‐m2 surface area) were prepared for each treatment with a bermudagrass [Cynodon dactylon (L.) Pers.] sod surface (using sod blocks) and composted dairy manure was surface‐applied at rates of 0, 4.5, 9, or 13.5 Mg ha−1 The three soil amendments were then applied to the boxes. Two 30‐min runoff events were conducted and runoff water was collected at 10‐min intervals and analyzed for RP(<0.45) Results indicated that the addition of ferrous sulfate was very effective at reducing the level of RP(<0.45) in runoff water, reducing RP(<0.45) from 1.3 mg L−1 for the highest compost rate with no amendment to 0.2 mg L−1 for the ferrous sulfate in the first 10 min of runoff. Lime and gypsum showed a small impact on reducing RP(<0.45), with a reduction in the first 10 min to 0.9 and 0.8 mg L−1, respectively. The ferrous sulfate reduced the RP(<0.45) in the tank at the end of the first runoff event by 66.3% compared with no amendment. In the second runoff event, the ferrous sulfate was very effective at reducing RP(<0.45) in runoff, with no significant differences in RP(<0.45) with application of 13.5 Mg ha−1 compost compared with no manure application. The results indicate that the addition of ferrous sulfate may greatly reduce RP(<0.45) losses in runoff and has considerable potential to be used on pasture, turfgrass, and filter strips to reduce the initial RP(<0.45) losses from manure application to the environment.
White Spruce Response to Co‐Composted Hydrocarbon‐Contaminated Drilling Waste
Authors: Choi Woo‐Jung , Chang Scott X. , Hao Xiying
Published: July 2005

There are growing interests to use co‐composted drilling wastes contaminated with hydrocarbons as growth media for planting in land reclamation. However, such use of the compost may have potential problems such as inherent toxicity of residual hydrocarbon and microbial N immobilization due to high compost C to N ratios. We investigated the growth, biomass production, N uptake, and foliar δ13C of white spruce (Picea glauca[Moench] Voss) seedlings in a pot experiment using 1‐, 2‐, 3‐, and 4‐yr‐old composts (with different hydrocarbon concentrations and C to N ratios) and a local noncontaminated soil with (200 kg N ha−1) or without N fertilization. Growth and N content of seedlings (particularly N content in roots) were lower when grown in the compost media as compared with those grown in the soil. Within the compost treatments seedling growth was affected by compost age, but the magnitude of growth reduction was not linearly proportional to hydrocarbon concentrations. Plant N uptake increased with compost age, which corresponds with an increase in indigenous mineral N concentration. Effects of N fertilization on N uptake were curtailed by the presence of indigenous mineral N (e.g., in the 4‐yr‐old compost) and by fertilization‐induced stimulation of microbial activities (e.g., in the 1‐yr‐old compost). The differences in foliar δ13C values between seedlings grown in compost and soil (P< 0.05) suggest that limitations on water uptake caused by the residual hydrocarbon might have been the predominant factor limiting seedling growth in the compost media. This study suggests that water stress caused by residual hydrocarbons may be a critical factor for the successful use of co‐composted drilling wastes as a growth medium.