bluuebunny/crossref_metadata_2025 huggingface dataset:
Fluctuations in bovine ovarian follicular fluid composition throughout the oestrous cycle
Authors: Orsi Nicolas M , Gopichandran Nadia , Leese Henry J , Picton Helen M , Harris Sarah E
Published: February 2005

Bovine oocyte maturation in vitro frequently results in abnormal cytoplasmic maturation and failure to acquire developmental competence. This is, in part, likely to be due to the non-physiological nutritional milieu to which oocytes are exposed. Improvements in oocyte developmental potential may be achieved by modelling nutrient profiles on those of preovulatory follicular fluid (FF). However, little is known about fluctuations in FF nutrient levels according to follicle dominance and oestrous cyclicity. This study therefore characterised the carbohydrate and amino acid profile of FF according to these parameters, and compared preovulatory FF composition with that of maturation medium. Carbohydrate concentrations (n = 121) were determined enzymatically whilst amino acid profiles (n = 40) were determined by reverse-phase HPLC. Pyruvate and glucose concentrations were unaffected by follicle dominance, whereas Stage III–IV lactate profiles were higher in non-dominant FF (P < 0.01). While most dominant FF amino acid concentrations were affected by oestrous stage, only glutamate, alanine, leucine and lysine levels fluctuated in non-dominant FF. Glucose and lactate concentrations were significantly negatively correlated, whereas most amino acids were significantly positively correlated with each other. Maturation medium had higher pyruvate and lower lactate concentrations than preovulatory FF (P < 0.001), whereas glucose level was similar. All amino acid levels (except histidine, taurine, alanine and tryptophan) differed significantly between maturation medium and preovulatory FF. These data indicated that FF composition varies throughout the oestrous cycle. Preovulatory FF nutrient profile differed from that of maturation medium, perhaps accounting for the poor developmental competence of in vitro matured oocytes. These data may contribute to the formulation of a nutritionally more physiological maturation medium.
Developmental Roles of the Mi-2/NURD-Associated Protein p66 in Drosophila
Authors: Kon Charlene , Cadigan Kenneth M , da Silva Sofia Lopes , Nusse Roel
Published: February 2005

The NURD and Sin3 histone deacetylase complexes are involved in transcriptional repression through global deacetylation of chromatin. Both complexes contain many different components that may control how histone deacetylase complexes are regulated and interact with other transcription factors. In a genetic screen for modifiers of wingless signaling in the Drosophila eye, we isolated mutations in the Drosophila homolog of p66, a protein previously purified as part of the Xenopus NURD/Mi-2 complex. p66 encodes a highly conserved nuclear zinc-finger protein that is required for development and we propose that the p66 protein acts as a regulatory component of the NURD complex. Animals homozygous mutant for p66 display defects during metamorphosis possibly caused by misregulation of ecdysone-regulated expression. Although heterozygosity for p66 enhances a wingless phenotype in the eye, loss-of-function clones in the wing and the eye discs do not have any detectable phenotype, possibly due to redundancy with the Sin3 complex. Overexpression of p66, on the other hand, can repress wingless-dependent phenotypes. Furthermore, p66 expression can repress multiple reporters in a cell culture assay, including a Wnt-responsive TCF reporter construct, implicating the NURD complex in repression of Wnt target genes. By co-immunoprecipitation, p66 associates with dMi-2, a known NURD complex member.
Transient Receptor Potential-Like Channels Are Essential for Calcium Signaling and Fluid Transport in a Drosophila Epithelium
Authors: MacPherson Matthew R , Pollock Valerie P , Kean Laura , Southall Tony D , Giannakou Maria E , Broderick Kate E , Dow Julian A T , Hardie Roger C , Davies Shireen A
Published: February 2005

Calcium signaling is an important mediator of neuropeptide-stimulated fluid transport by Drosophila Malpighian (renal) tubules. We demonstrate the first epithelial role, in vivo, for members of the TRP family of calcium channels. RT-PCR revealed expression of trp, trpl, and trpγ in tubules. Use of antipeptide polyclonal antibodies for TRP, TRPL, and TRPγ showed expression of all three channels in type 1 (principal) cells in the tubule main segment. Neuropeptide (CAP2b)-stimulated fluid transport rates were significantly reduced in tubules from the trpl302 mutant and the trpl;trp double mutant, trpl302;trp343. However, a trp null, trp343, had no impact on stimulated fluid transport. Measurement of cytosolic calcium concentrations ([Ca2+]i) in tubule principal cells using an aequorin transgene in trp and trpl mutants showed a reduction in calcium responses in trpl302. Western blotting of tubule preparations from trp and trpl mutants revealed a correlation between TRPL levels and CAP2b-stimulated fluid transport and calcium signaling. Rescue of trpl302 with a trpl transgene under heat-shock control resulted in a stimulated fluid transport phenotype that was indistinguishable from wild-type tubules. Furthermore, restoration of normal stimulated rates of fluid transport by rescue of trpl302 was not compromised by introduction of the trp null, trp343. Thus, in an epithelial context, TRPL is sufficient for wild-type responses. Finally, a scaffolding component of the TRPL/TRP-signaling complex, INAD, is not expressed in tubules, suggesting that inaD is not essential for TRPL/TRP function in Drosophila tubules.
Gal80 Dimerization and the Yeast GAL Gene Switch
Authors: Pilauri Vepkhia , Bewley Maria , Diep Cuong , Hopper James
Published: February 2005

The Saccharomyces cerevisiae Gal80 protein has two binding partners: Gal4 and Gal3. In the absence of galactose, Gal80 binds to and inhibits the transcriptional activation domain (AD) of the GAL gene activator, Gal4, preventing GAL gene expression. Galactose triggers an association between Gal3 and Gal80, relieving Gal80 inhibition of Gal4. We selected for GAL80 mutants with impaired capacity of Gal80 to bind to Gal3 or Gal4AD. Most Gal80 variants selected for impaired binding to Gal4AD retained their capacity to bind to Gal3 and to self-associate, whereas most of those selected for impaired binding to Gal3 lost their ability to bind to Gal4AD and self-associate. Thus, some Gal80 amino acids are determinants for both the Gal80-Gal3 association and the Gal80 self-association, and Gal80 self-association may be required for binding to Gal4AD. We propose that the binding of Gal3 to the Gal80 monomer competes with Gal80 self-association, reducing the amount of the Gal80 dimer available for inhibition of Gal4.
Mitochondrial Translation
Authors: Chiron Stéphane , Suleau Audrey , Bonnefoy Nathalie
Published: February 2005

The translation elongation factor EF-Tu is a GTPase that delivers amino-acylated tRNAs to the ribosome during the elongation step of translation. EF-Tu/GDP is recycled by the guanine nucleotide exchange factor EF-Ts. Whereas EF-Ts is lacking in S. cerevisiae, both translation factors are found in S. pombe and H. sapiens mitochondria, consistent with the known similarity between fission yeast and human cell mitochondrial physiology. We constructed yeast mutants lacking these elongation factors. We show that mitochondrial translation is vital for S. pombe, as it is for human cells. In a genetic background allowing the loss of mitochondrial functions, a block in mitochondrial translation in S. pombe leads to a major depletion of mtDNA. The relationships between EF-Ts and EF-Tu from both yeasts and humans were investigated through functional complementation and coexpression experiments and by a search for suppressors of the absence of the S. pombe EF-Ts. We find that S. cerevisiae EF-Tu is functionally equivalent to the S. pombe EF-Tu/EF-Ts couple. Point mutations in the S. pombe EF-Tu can render it independent of its exchange factor, thereby mimicking the situation in S. cerevisiae.
Processivity Clamp gp45 and ssDNA-Binding-Protein gp32 Modulate the Fidelity of Bacteriophage RB69 DNA Polymerase in a Sequence-Specific Manner, Sometimes Enhancing and Sometimes Compromising Accuracy
Authors: Bebenek Anna , Carver Geraldine T , Kadyrov Farid A , Kissling Grace E , Drake John W
Published: February 2005

Numerous studies of the impact of accessory proteins upon the fidelity of DNA synthesis have provided a complex and sometimes discordant picture. We previously described such an analysis conducted in vitro using various bacteriophage RB69 gp43 mutator DNA polymerases with or without the accessory proteins gp32 (which binds single-stranded DNA) plus gp45/44/62 (processivity clamp and its loaders). Mutations were scored at many sites in the lacZα mutation reporter sequence. Unexpectedly, the accessory proteins sometimes decreased and sometimes increased fidelity at a handful of specific sites. Here, we enlarge our analysis with one particular mutator polymerase compromised in both insertion accuracy and proofreading and also extend the analysis to reactions supplemented only with gp32 or only with gp45/44/62. An overall 1.56-fold increase in mutation frequencies was produced by adding single or multiple accessory proteins and was driven mainly by increased Ttemplate•Gprimer mispairs. Evidence was found for many additional sites where the accessory proteins influence fidelity, indicating the generality of the effect. Thus, accessory proteins contribute to the site-specific variability in mutation rates characteristically seen in mutational spectra.
A Systematic High-Throughput Screen of a Yeast Deletion Collection for Mutants Defective in PHO5 Regulation
Authors: Huang Sidong , O'Shea Erin K
Published: February 2005

In response to phosphate limitation, Saccharomyces cerevisiae induces transcription of a set of genes important for survival. One of these genes is PHO5, which encodes a secreted acid phosphatase. A phosphate-responsive signal transduction pathway (the PHO pathway) mediates this response through three central components: a cyclin-dependent kinase (CDK), Pho85; a cyclin, Pho80; and a CDK inhibitor (CKI), Pho81. While signaling downstream of the Pho81/Pho80/Pho85 complex to PHO5 expression has been well characterized, little is known about factors acting upstream of these components. To identify missing factors involved in the PHO pathway, we carried out a high-throughput, quantitative enzymatic screen of a yeast deletion collection, searching for novel mutants defective in expression of PHO5. As a result of this study, we have identified at least nine genes that were previously not known to regulate PHO5 expression. The functional diversity of these genes suggests that the PHO pathway is networked with other important cellular signaling pathways. Among these genes, ADK1 and ADO1, encoding an adenylate kinase and an adenosine kinase, respectively, negatively regulate PHO5 expression and appear to function upstream of PHO81.
RacGap50C Negatively Regulates Wingless Pathway Activity During Drosophila Embryonic Development
Authors: Jones Whitney M , Bejsovec Amy
Published: February 2005

The Wingless (Wg)/Wnt signal transduction pathway directs a variety of cell fate decisions in developing animal embryos. Despite the identification of many Wg pathway components to date, it is still not clear how these elements work together to generate cellular identities. In the ventral epidermis of Drosophila embryos, Wg specifies cells to secrete a characteristic pattern of denticles and naked cuticle that decorate the larval cuticle at the end of embryonic development. We have used the Drosophila ventral epidermis as our assay system in a series of genetic screens to identify new components involved in Wg signaling. Two mutant lines that modify wg-mediated epidermal patterning represent the first loss-of-function mutations in the RacGap50C gene. These mutations on their own cause increased stabilization of Armadillo and cuticle pattern disruptions that include replacement of ventral denticles with naked cuticle, which suggests that the mutant embryos suffer from ectopic Wg pathway activation. In addition, RacGap50C mutations interact genetically with naked cuticle and Axin, known negative regulators of the Wg pathway. These phenotypes suggest that the RacGap50C gene product participates in the negative regulation of Wg pathway activity.
Single molecule raman spectroscopy and local work function fluctuations
Authors: Haran Gilad
Published: February 2005

Single molecule Raman spectroscopy provides information on individual molecules with vibrational‐level resolution. The unique mechanisms leading to the huge Raman cross‐section enhancement necessary for single molecule sensitivity are under intense investigation in several laboratories. We recently published an analysis of large spectral fluctuations in single molecule spectra of Rhodamine 6G on silver surfaces. The appearance of the fluctuations in two particular vibrational bands, and their dependence on several parameters, suggested that they originate in a charge transfer interaction of an adsorbed molecule with the surface. We argued that the fluctuations are due to variations of the local work function at the position of the molecule. In the current paper the fluctuations are further analyzed in terms of the intensity ratio between a fluctuating and a quiescent band, and it is found that the distribution of this ratio is independent of laser power, unlike the correlation time of the fluctuations. We show that a simple model, based on the energetics of charge transfer, can be used to extract the local work function distribution from the intensity ratio distribution. In a second experiment, single molecule spectra are collected from colloids immersed in water and in glycerol and a threefold decrease in fluctuation rate is found in the more viscous fluid. This indicates that surface dynamics are indeed responsible for the fluctuations, involving the motion of the adsorbed molecule and possibly also that of surface silver atoms around it.
Fluctuations and single molecules
Authors: Plakhotnik Taras
Published: February 2005

The fluorescence of single molecules coupled to a thermal bath is studied both experimentally and theoretically. The effect of different fluctuations on the coherence properties of resonance fluorescence is considered first. Coherence is measured in an interference experiment where a single molecule is used as a light source. A standard approach based on the optical Bloch equations apparently provides quite an accurate description of the interference experiment. Systems with long correlation times (where spectra are time dependent on any timescale) are considered next. It is shown that intensity—time—frequency correlation spectroscopy, which provides both high signal‐to‐noise ratio and high time resolution, is very suitable for such a case. The Bloch equations are further tested in an experiment where the shape of an excitation spectral line of a single molecule is accurately measured over six orders of magnitude of the exciting laser power. Significant deviations from the predictions of the Bloch equations are found. The role of critical parameters—the correlation time of the bath, the Rabi oscillation period, and the coupling constant between the bath and the molecule—is discussed. The paper also includes a short general introduction to the methodology of single‐molecule studies.
1/f Spin noise and a single spin detection with STM
Authors: Manassen Yishay , Balatsky Alexander V.
Published: February 2005

We propose a novel mechanism for single spin detection based on the 1/f spin current noise. We postulate that the 1/f spin noise for the tunneling current is similar to the ubiquitous 1/f noise in magnetic systems. Magnetic coupling between tunneling electrons and localized spin S then leads to the peak at Larmor frequency in the power spectrum of the electric current fluctuations I2ω. The elevated noise in the current spectrum will be spatially localized near the magnetic site. The difference in the power spectra taken at the Larmor frequency and elsewhere would reveal the peak in the spectrum. We argue that the signal‐to‐noise ratio for this mechanism is on the order of one. In addition, we discuss the asymmetric line shapes observed regularly with this measurement. We show that such line shapes are in accordance with the random sampling done with the tunneling electrons. Yet this predicts a line width at least one order of magnitude larger than observed experimentally, which is likely to be due to electrostatic repulsion between the tunneling electrons and temporal correlations in the tunneling process.
Electronic Level Structure and Single Electron Tunneling Effects in CdSe Quantum Rods
Authors: Rothenberg Eli , Mokari Taleb , Kazes Miri , Banin Uri , Katz David , Steiner Dov , Millo Oded
Published: February 2005

Optical spectroscopy and scanning tunneling microscopy are used to study the size and shape dependence of the electronic states in CdSe quantum rods. Samples having average rod dimensions ranging from 10 to 60 nm in length and 3.5 to 7 nm in diameter, with aspect ratios varying between 3 to 12, were investigated. Both size‐selective optical spectroscopy and tunneling spectra on single rods show that the level structure depends primarily on the rod diameter and not on length. With increasing diameter, the band gap and the excited state level spacings shift to the red. The level structure is assigned using a multi‐band effective‐mass model. We shall also discuss the effect of single electron charging on the tunneling spectra, possibly reflecting the quantum rod level degeneracy, and its dependence on the tunneling junction parameters.
Following Single Molecules by Force Spectroscopy
Authors: Dudko Olga K. , Filippov Alexander E. , Klafter Joseph , Urbakh Michael
Published: February 2005

Dynamic force spectroscopy of single molecules, in which an adhesion bond is driven away from equilibrium by a spring pulled with velocity V, is described by a model that predicts the distribution of rupture forces (mean and variance), all amenable to experimental tests. The distribution has a pronounced asymmetry, which has recently been observed experimentally. The mean rupture force follows a (lnV)2/3 dependence on the pulling velocity and differs from earlier predictions. Interestingly, at low pulling velocities a rebinding process is observed whose signature is an intermittent behavior of the spring force that delays the rupture. Based on the rupture mechanism, we propose a new “pick‐up‐and‐put‐down” method to manipulate individual molecules with scanning probes. We demonstrate that the number of molecules picked up by the tip and deposited at a different location can be controlled by adjusting the pulling velocity of the tip and the distance of closest approach of the tip to the surface.
Photoinduced Processes in Silicon Nanoparticles
Authors: Martin JÖRg , Cichos Frank , Chan Iu Y. , Huisken Friedrich , Borczyskowski Christian Von
Published: February 2005

Silicon nanocrystals have been prepared from gas‐phase pyrolysis and electrochemical etching of silicon. Confocal and wide‐field optical microscopy have been performed on size‐selected ensembles and single silicon nanocrystals. Single particles exhibit photoluminescence blinking effects that are interrelated with photo‐induced (reversible) bleaching effects of the ensemble. The blinking dynamics follow a power law statistic of on‐ and off‐times, revealing that even single nanoparticles are subject to strong disorder effects. This is supported by optically detected magnetic resonance (ODMR) experiments on silicon nanoparticles achieved for the first time via microscopic techniques.
Carotenoids of Different Types and Concentrations in Commercial Formulated Fish Diets Affect Color and Its Development in the Skin of the Red Oranda Variety of Goldfish
Authors: Wallat Geoffrey K , Lazur Andrew M , Chapman Frank A
Published: February 2005

The skin color of an orange–red hue in the Red Oranda variety of goldfish Carassius auratus is identified as a desirable and essential sales factor by hobbyists and commercial producers. This study used six different commercial diets (Arkat, BioKyowa, Silver Cup, Southern States, VibraGro, and Zeigler Tropical) to demonstrate the highly variable effect commercial diets could have on the skin coloration, survival, and growth of juvenile Red Oranda goldfish. Diets were selected based on their popular use in the tropical fish industry, the manufacturers' guaranteed nutritional analysis, and advertised color-enhancing ability. Goldfish were raised for 20 weeks in well water or pond water. Goldfish exhibited the best orange–red skin coloration when fed the VibraGro, Silver Cup, and Zeigler Tropical diets. BioKyowa feed imparted greenish-yellow skin coloration, and fish exhibited significantly (P < 0.05) faster growth. The Arkat and Southern States feeds produced light olive to greenish-yellow skin coloration, and fish exhibited poor survival and growth. Skin color acquisition was faster in pond-water-reared fish than those reared in well water. The carotenoid content in the commercial diets was determined by spectrophotometry and high-performance liquid chromatography. Although the carotenoid types in the different diets were similar, their concentration levels varied widely.
Mortality of Fish Larvae Exposed to Varying Concentrations of Cyclopoid Copepods
Authors: Frimpong Emmanuel A , Lochmann Steve E
Published: February 2005

Cyclopoid copepods can prey on freshwater fish larvae. The magnitude of predation is related to the size and concentrations of the cyclopoid copepods and the size of the fish larva; it is also likely to be specific to certain species. We studied 5-d-old larvae of sunshine bass (female white bass Morone chrysops × male striped bass M. saxatilis), golden shiner Notemigonus crysoleucas, fathead minnow Pimephales promelas, and goldfish Carassius auratus in four separate experiments. Larvae were stocked at 20/L into 2 L of water containing various concentrations of the cyclopoid copepods Cyclops vernalis and Mesocyclops vericans to ascertain the effect of predation on mortality. We also compared predation rates observed in this study with rates predicted by an empirical model of crustacean predation on fish larvae from the literature. Sunshine bass alone were susceptible to predation mortality at the cyclopoid copepod concentrations used in this study. Mortality at 400 cyclopoids/L was significantly higher than mortality at 0–100 cyclopoids/ L. Mortality at 500 cyclopoids/L was significantly greater than mortality at any other treatment concentration. The observed predation rates were much lower than the predation rates predicted by the model. Stocking sunshine bass larvae at 4.11 mm total length or larger into ponds with fewer than 300 cyclopoids/L probably represents a low risk of predation. Golden shiners, fathead minnow, and goldfish larger than 5 mm total length that are stocked in ponds with fewer than 500 cyclopoids/L would also probably experience little cyclopoid copepod predation.
Growth of Postlarval Macrobrachium rosenbergii at Two Temperatures
Authors: Arana-Magallón F C , Ortega-Salas A A
Published: February 2005

Postlarvae of the giant Malaysian prawn Macrobrachium rosenbergii were reared for a 120-d period under laboratory conditions at 20°C and 33°C. We stocked 480 50-d-old postlarvae in eight 70-L aquaria. A balanced commercial feed containing 40% protein was supplied daily at 20% to 9% of body weight during the first 2 months and at 5% to 3% of body weight during the final 2 months. Live brine shrimp Artemia franciscana were also provided as a supplemental food. The growth of the giant Malaysian prawn was significantly greater at 33°C than at 20°C. Basic knowledge of giant Malaysian prawn rearing requirements under artificial conditions is important for the production of juveniles as stocks for large-scale prawn culture.
Preliminary Observations of Topical Gill Application of Reproductive Hormones for Induced Spawning of a Tropical Ornamental Fish
Authors: Hill Jeffrey E , Baldwin John D , Graves Jeffrey S , Leonard Robert , Powell James F F , Watson Craig A
Published: February 2005

Hormone injection is a common spawning induction technique in aquaculture but is of limited use in small species with low fecundity. An alternative to injection for such species is topical gill application. We conducted an experiment with female rainbow sharks Epalzeorhynchos erythrurus (Cyprinidae) in one control group and three treatment groups: (1) topical gill application of dimethyl sulfoxide (DMSO), (2) topical gill application of DMSO and Ovaprim, and (3) an Ovaprim intramuscular (IM) injection. Ovaprim contains a salmonid gonadotropin-releasing hormone analog and a dopamine antagonist. Fish were anesthetized, treated, and placed into recovery tanks. Fish were manually checked for ovulation by exerting abdominal pressure at 8, 10, and 11 h posttreatment and were observed for mortality during a 24-h period. Ovulation varied significantly: we found no ovulation of females in the control or DMSO groups, 78% ovulation in the DMSO plus Ovaprim group, and 100% ovulation in the Ovaprim IM injection group. Only two mortalities occurred in 24 h, both in the injected group. Use of DMSO as a solvent for topical gill application of hormones shows some promise as a spawning induction technique for tropical ornamental fishes.
Routine Measures of Stress Are Reduced in Mature Channel Catfish during and after AQUI-S Anesthesia and Recovery
Authors: Small Brian C , Chatakondi Nagaraj
Published: February 2005

Mature channel catfish Ictalurus punctatus were exposed to water containing three different concentrations (20, 40, and 60 mg/L) of AQUI-S (50% isoeugenol) during routine handling procedures at a commercial catfish facility. Anesthetic efficacy, recovery time, and the effects of AQUI-S on routine measures of stress were compared with similar measures in a group of fish sampled prior to anesthesia (preanesthesia [PA] group) and a group anesthetized with 100 mg tricaine methanesulfonate (TMS)/L. On average, all the fish lost equilibrium at 8.0, 3.9, and 3.7 min when anesthetized in 20, 40, and 60 mg AQUI-S/L, respectively. Fish anesthetized with TMS lost equilibrium at 4.5 min. Recovery time in freshwater was 2.1, 2.8, and 5.3 min for fish anesthetized in 20, 40, and 60 mg/L AQUI-S, respectively. Recovery time after TMS anesthesia was 1.7 min. Short-term (24-h) survival was 100% for all treatments, and long-term (21-d) survival ranged from 87.5% for TMS-anesthetized fish to 98.8% for fish anesthetized in 40 mg/L AQUI-S. All anesthetic treatments significantly reduced (P < 0.05) plasma cortisol levels relative to PA fish, and circulating cortisol was lower (P < 0.05) in all AQUI-S−anesthetized fish than in TMS-anesthetized fish. Plasma glucose concentrations were significantly lower (P < 0.05) in fish anesthetized with 40 mg/L AQUI-S than in PA and TMS-treated fish after both anesthetization and recovery. Plasma lactate and chloride concentrations were not reduced (P > 0.05) in any treatment compared with the levels in PA fish. Fish anesthetized with 40 mg/L AQUI-S had lower (P < 0.05) plasma lactate levels after recovery than TMS-anesthetized fish, and plasma chloride levels were significantly lower (P < 0.05) immediately following AQUI-S anesthesia at all concentrations than in fish anesthetized with TMS. Anesthesia did not affect (P > 0.05) postrecovery plasma chloride concentrations. Overall, AQUI-S exhibited efficacy as an anesthetic for mature channel catfish and demonstrated stress-reducing properties during handling procedures.
Pattern of Discharge and Mass Loading during Drainage of Excavated Ponds Used for Food Fish Production of Channel Catfish
Authors: Hargreaves John A , Tucker Craig S , Kingsbury Susan K
Published: February 2005

We evaluated the temporal pattern of solids, organic matter, and nutrient concentrations in the discharge effluent of three commercial-size excavated ponds with two types of drainage structures used in catfish production in Mississippi. Measurements of effluent water quality and pond stage elevation were used to calculate solids, organic matter, and nutrient mass loading when ponds were drained. Solids, organic matter, and nutrient concentrations in effluent from ponds with fixed internal drains were very high during the first 10– 30 min of pond draining. Thereafter, effluent solids and nutrient concentrations were similar to those of the bulk pond water. The initial flush of effluent contained solids that settle easily. Mass discharge was directly proportional to volume discharged in two ponds. In the third pond, mass discharge increased as a function of pond volume because poorly consolidated pond sediment exposed during draining was eroded by rainfall and wind-generated waves. Average mass discharge (kg/ha) from draining the three ponds was as follows: total suspended solids = 976, 5-d biochemical oxygen demand = 84, total nitrogen = 46, and total phosphorus = 3.5. These mass loading values can be annualized by dividing by the interval between pond drainings. Total annual mass loading can be calculated by adding annualized mass discharge from pond draining to mass discharge from pond overflow.
Oxygen transport and cell viability in an annular flow bioreactor: Comparison of laminar Couette and Taylor‐vortex flow regimes
Authors: Curran Stephen J. , Black Richard A.
Published: February 2005

Rotating wall vessel bioreactors have been proposed as a means of controlling the fluid dynamic environment during long‐term culture of mammalian cells and engineered tissues. In this study, we show how the delivery of oxygen to cells in an annular flow bioreactor is enhanced by the forced convective transport afforded by Taylor vortex flows. A fiberoptic oxygen probe with negligible lag time was used to measure the dissolved oxygen concentration in real time and under carefully controlled aeration conditions. From these data, the overall mass transfer coefficients were calculated and mass transport correlations determined under laminar Couette flow conditions and discrete Taylor vortex flow regimes, including laminar, wavy, and turbulent flows. While oxygen transport in Taylor vortex flows was significantly greater, and the available oxygen exceeded that consumed by murine fibroblasts in free suspension, the proportion of cells that remained viable decreased with increasing Reynolds number (101.8 < Rei < 1018), which we attribute to the action of fluid shear stresses on the cells as opposed to any limitation in mass transport. Nevertheless, the results of this study suggest that laminar Taylor‐vortex flow regimes provide an effective means of maintaining the levels of oxygen transport required for long‐term cell culture. ©2005 Wiley Periodicals, Inc.
Host limits to accurate human growth hormone production in multiple plant systems
Authors: Russell Douglas A. , Spatola Lori A. , Dian Titik , Paradkar Vikram M. , Dufield Dawn R. , Carroll James A. , Schlittler Michael R.
Published: February 2005

Human growth hormone (hGH) is not only a valuable recombinant therapeutic protein for hormone deficiency indications, but is also an extensively characterized molecule both from recombinant bacterial systems and as circulating in humans. We describe the characterization of hGH produced in three different plant systems: tobacco cell culture, soy seed, and maize seed. The data indicate highest production in the maize seed system, with continued productivity over multiple generations, and when bred to a new host genotype for improved productivity. Purification indicated significant material of the correct structure from both plant cell culture and maize seed, with maize seed also showing correct activity relative to that produced by Escherichia coli. However, all systems showed some proteolyzed hGH, with data from gel electrophoresis, mass spectrometry, and peptide mapping localizing to a region of the protein also prone to cleavage in some other systems. Together, the data indicate the dependence of recombinant protein accumulation on posttranslational processes in different host systems. ©2005 Wiley Periodicals, Inc.
Magnetic resonance microscopy analysis of advective transport in a biofilm reactor
Authors: Gjersing Erica L. , Codd Sarah L. , Seymour Joseph D. , Stewart Philip S.
Published: February 2005

In this article we present magnetic resonance microscopy (MRM) characterization of the advective transport in a biofilm capillary reactor. The biofilm generates non‐axial flows that are up to 20% of the maximum axial velocity. The presence of secondary velocities of this magnitude alters the mass transport in the bioreactor relative to non‐biofilm fouled reactors and questions the applicability of empirical mass transfer coefficient approaches. The data are discussed in the context of simulations and models of biofilm transport and conceptual aspects of transport modeling in complex flows are also discussed. The variation in the residence time distribution due to biofilm growth is calculated from the measured propagator of the motion. Dynamical systems methods applied to model fluid mixing in complex flows are indicated as a template for extending mass transport theory to quantitatively incorporate microscale data on the advection field into macroscale mass transfer models.© 2005 Wiley Periodicals, Inc.
How to deal with difficult microsurgical end‐to‐side anastomoses
Authors: Verhelle Nicolas Aubrey Charles , Heymans Olivier
Published: February 2005

Although unexplained thrombotic failures still exist, the majority of free‐flap failures are due to identifiable technical failures, indicating that an excellent operative technique remains the key point. However, some clinical circumstances, such as damaged or deeply located vessels, are related to a higher thrombotic risks, demanding refinements of the microsurgical procedure to avoid higher failure rates. We reviewed 195 free flaps in the lower leg in order to quantify these situations and how we dealt with them. In total, six flaps were performed with a T‐interposition to cope with difficult end‐to‐side anastomoses on damaged vessels. In two cases, the use of a funnel‐shaped vein graft facilitated difficult end‐to‐side anastomoses in the popliteal area. The authors believe that these refinements of microsurgery should not be first‐choice procedures, but they have proven to be a useful tool for certain microsurgical reconstructions. © 2005 Wiley‐Liss, Inc. Microsurgery 25:1–6, 2005.
Morphological and functional evaluation of leg‐muscle reinnervation after coupler coaptation of the divided rat sciatic nerve
Authors: Lutz Barbara S. , Lidman Disa
Published: February 2005

Mechanical couplers are successfully used for microvascular venous anastomoses. The advantages include a simple and fast technique and a high patency rate. Couplers offer a secluded coaptation site, and might also be of use in peripheral nerve repair. The present study was designed to investigate coupler coaptation of the rat sciatic nerve, evaluating the number and locations of motor and sensory neurons projecting to the selected muscles as well as stimulation‐induced muscle contraction force. Adult rats underwent either suture or coupler repair after left sciatic nerve transection. In all rats, the experimental side was compared to the healthy right side. Evaluation after 20 weeks included retrograde labeling of motoneurons and dorsal root ganglion neurons projecting to the tibial anterior muscle and to the tibial posterior muscle, histology, muscle contraction force (tibial anterior muscle and gastrocnemius muscle), and a pinch reflex test. The results show that the suture and the coupler groups did not differ significantly regarding the examined parameters, except for discrete signs of nerve compression at the coaptation site after coupler repair due to fibrous tissue ingrowth. However, this did not impair axonal regeneration. Importantly, axonal outgrowth from the repair site to the surrounding tissue was not observed after coupler coaptation, but it was observed after suture repair. These results suggest that couplers may be of value for repair of nerves in adjacency to avoid axonal crisscrossing between nerves during regeneration. © 2005 Wiley‐Liss, Inc. Microsurgery 25:1–6, 2005.
Drugs from emasculated hormones: The principle of syntopic antagonism
Authors: Black James
Published: February 2005

This lecture outlines the early stages in the discovery of adrenaline β-receptor antagonists and of the histamine H2-receptor antagonists. It ends with a brief personal view about future research.
Collagen binding proteins derived from the embryonic fibroblast cell surface recognize arginine-glycine-aspartic acid
Authors: Ogle Roy C. , Little Charles D.
Published: February 2005

Several cell surface proteins (Mr=120,000, 90,000, 63,000 and 47,000) apparently integral to embryonic fibroblast plasma membranes were extracted with detergent and isolated by collagen affinity chromatography. Certain of these proteins (Mr=120,000, 90,000 and 47,000) were specifically eluted from collagen affinity columns by synthetic peptides containing the amino acid sequence arginyl-glycyl-aspartic acid (RGD). These data show that a number of collagen binding proteins exist on the embryonic fibroblast cell surface. Some of the proteins may be collagen receptors binding to RGD sequences in the collagen molecule while at least one of the proteins (Mr=63,000) recognizes features other than RGD.
Interaction between diazepam and oral antidiabetic agents on serum glucose, insulin and chromium levels in rats
Authors: Al-Ahmed F. A. A. , El-Denshary E. S. M. , Zaki M. , El-Sawaf H. A. , Abu-Jayyab A. R.
Published: February 2005

This study was undertaken to investigate the effect of diazepam in the presence and absence of glibenclamide, metformin or their combination on serum levels of glucose, insulin and chromium in rats. Results indicated that diazepam (10 mg/kg i.p.) induced marked hyperglycaemic effects in hyperglycaemic rats. This effect was associated with significant reductions in serum chromium levels and insignificant reduction in serum insulin levels. Diazepam-induced hyperglycaemia was counter-acted by concurrent administration of glibenclamide (5 mg/kg orally), metformin (500 mg/kg orally) or their combination. The effect of diazepam on serum chromium level was counteracted partially by administration of glibenclamide and augmented in the presence of metformin or its combination with glibenclamide. It is concluded that the diazepam-induced hyperglycaemia, as well as the hypoglycaemic effect of glibenclamide, might be related to changes in serum chromium levels.
Erythrocyte membrane (Ca2++Mg2+)-ATPase in human protein-energy malnutrition
Authors: Olorunsogo Olufunso O.
Published: February 2005

Calmodulin-free ghost membranes were prepared from erythrocytes of kwashiorkor children and from healthy children in the same age bracket. In the absence of calmodulin, the specific activity of Mg2+-dependent Ca2+-pumping ATPase (Ca2++Mg2+-ATPase) of kwashiorkor membranes was more than 40 percent lower than the specific activity of the normal enzymes, whose maximum velocity was increased by at least four-fold by the modulator protein. In constrast, the maximum velocity of the enzymes of kwashiorkor membranes was enhanced by calmodulin by about 11/2 times the basal activity of the normal enzymes and by 2 times the basal activity of the kwashiorkor enzymes. The affinity of the pump for ATP was lower in the membranes of kwashiorkor children (Km for ATP=30.6±2.8 μM ATP) in comparison to normal membranes (Km for ATP=21.7±2.0 μM ATP). Similarly, calmodulin-affinity of the enzymes, was lower in kwashiorkor membranes than in the normal membranes irrespective of source of calmodulin. Calmodulin from haemolysates of kwashiorkor red cells activated the enzymes of normal and kwashiorkor membranes to the same degree as calmodulin partially purified from the haemolysate of healthy children. A determination of the dependence of the activity of the pump on calcium in the absence and presence of calmodulin reveals that the affinity of the kwashiorkor enzymes for Ca2+ is at least 70 percent lower than that of enzymes of normal membranes. Altogether, these findings suggest that the Ca2+-pumping ATPase of kwashiorkor membranes is less functional than the enzymes of healthy erythrocytes.
Peptide histidine valine-42 stimulates gastric acid secretion in man
Authors: Nikou G. C. , Yiangou Y. , Chrysanthou B. J. , Domin J. , Bloom S. R.
Published: February 2005

The effect of peptide histidine valine-42 (PHV-42) on gastric acid secretion was studied in man. PHV-42 was infused into 5 healthy volunteers at a dose of 10 pmol/kg/min. This dose caused a significant stimulation of basal gastric acid and potassium output. there were no significant changes in circulating gastrin throughout the infusion. In 2 subjects with a background of submaximal pentagastrin stimulation, PHV-42 infusion at the same dose did not alter acid secretion in either subject. The previous observation that PHV-42 is found particularly in the stomach and the new finding that it stimulates basal gastric secretion suggest the possibility that PHV-42 could have a role in local control of acid secretion.
Yeasts in molecular biology. Spheroplast preparation with Canadida utilis, Schizosaccharomyces pombe and Saccharomyces cerevisiae
Authors: Mann William , Jeffery Jonathan
Published: February 2005

Efficient preparation of spheroplasts from Candida utilis, Saccharomyces cerevisiae, and Schizosaccharomyces pombe, using a purified mixture of enzymes from Trichoderma harzianum, is described. Limitations of other methods, and differences between yeasts are demonstrated.
Monoclonal antibodies to rabbit liver cathepsin B
Authors: Wardale R. John , Maciewicz Rose A. , Etherington David J.
Published: February 2005

Three stable hybridoma cell lines (AF8, BC11, CE2) have been produced that secrete antibodies specific for cathepsin B. These have been characterized by ELISA, SDS-PAGE immunostaining, immunoprecipitation and immunofluorescent staining. CE2 immunoprecipitated native cathepsin B with retention of enzymic activity, but failed to cross-react with the alkali-denatured enzyme. BC11 bound only to the denatured form of cathepsin B and AF8 cross-reacted with both native and denatured cathepsin B. However, unlike CE2-immunoprecipitated enzyme, activity could be detected only after dissociation of the antigen-AF8 antibody complex. No cross reaction was found with any lysosomal protein includihg the cysteine proteinases, catbepsins H and L.
Muscle pain after exercise is linked with an inorganic phosphate increase as shown by31P NMR
Authors: Aldridge R. , Cady E. B. , Jones D. A. , Obletter G.
Published: February 2005

31P nuclear magnetic resonance (NMR) spectra were obtained from the forearm muscles of 5 subjects before and after performing a muscle stretching (eccentric) exercise routine. Spectra collected before and immediately after exercise showed normal resting phosphorylated metabolite levels and unchanged intracellular pH (pHi). Measurements made on the day following exercise, when muscular pain was apparent, revealed an elevated inorganic phosphate level. No significant changes in other metabolites or pHi were detected. This study gives the first indication of biochemical change following a form of exercise that is associated with considerable muscle pain and damage. The findings may help in understanding pathological processes resulting in pain and damage in muscle.
Effectivity of dolichyl phosphates with different chain lengths as acceptors of nucleotide activated sugars
Authors: Löw P. , Peterson E. , Mizuno M. , Takigawa T. , Chojnacki T. , Dallner G.
Published: February 2005

Chemical synthesis of different S-forms of dolichyl-P was performed in order to investigate the use of these polyprenes in mannosyl, glucosyl and glucosaminyl transferase reactions. Determination of the Vmax values for a series of dolichyl-P demonstrated that the velocities of transferase reactions with all those dolichyl-P derivatives present in animal tissues are largely the same. The apparent Km values for the various dolichyl-P in the transferase system studied differed, but this property does not appear to have physiological importance.
Isoelectric focusing of the human TSH receptor A subunit
Authors: Hashim F. A. , Jones E. Davies , Howells R. D. , Rees Smith B.
Published: February 2005

The water soluble A subunit of the human TSH receptor has been shown to have an isoelectric point of 5. As both TSH and TSH receptor antibodies have isoelectric points in the region of 8–10, charge-charge interactions must be of major importance in the binding of hormone or antibody to the TSH receptor A subunit.
Current concepts of basement-membrane structure and function
Authors: Grant Michael E. , Heathcote J. Godfrey , Orkin Roslyn W.
Published: February 2005

Conclusion

In this brief review we have attempted to describe the known components of basement membranes in relation to the morphology and function of these matrices. Further details of the molecular structures and biosynthesis of these components may be found in original papers and in various reviews (Kefalides, 1973; Spiro, 1976; Kefalides et al., 1979; Heathcote & Grant, 1981).

Although basement membranes appear to contain essentially similar protein and carbohydrate moieties, the proportions and organization of these may differ and, in the opinion of the authors, the key to an understanding of basement membranes lies in the recognition of this heterogeneity. At present, structural models of basement membrane are far from satisfactory and should be regarded with reservation.
Effects of cyclic AMP on DNA replication and protein biosynthesis in fetal rat islets of Langerhans maintained in tissue culture
Authors: Swenne I.
Published: February 2005

The regulatory role of cyclic AMP (cAMP) in the growth and insulin production of the islet organ in vitro has been investigated. The effects of dibutyryl cyclic AMP (dbcAMP), theophylline, and 3-isobutyl-1-methylxanthine (IBMX) on DNA replication and on the biosynthesis of RNA and insulin in fetal rat islets of Langerhans maintained in tissue culture have been studied. Raising the glucose concentration from 2.7 mM to 16.7 mM caused a two-fold increase in DNA replication. Both dbcAMP and theophylline markedly inhibited the DNA replication at all glucose Concentrations studied. Low concentrations of IBMX stimulated DNA synthesis. However, at higher concentrations of this drug, known to considerably increase the islet cAMP levels, a marked inhibition of islet DNA replication was observed. Both (pro)insulin and total protein biosynthesis were stimulated by glucose, whereas dbcAMP stimulated only the (pro)insulin biosynthesis. Since glucose is known to raise islet intracellular levels of cAMP, which is known to be an inhibitor of cellular proliferation, the observed glucose stimulation of both islet-cell DNA replication and insulin production appeared conflicting. It is suggested that this dual effect of glucose may depend on a stimulation of proliferation in a limited pool of islet cells which may not exhibit an increase in cAMP.