bluuebunny/crossref_metadata_2025 huggingface dataset:
Transcriptional Switch of the
dia1
and
impA
Promoter during the Growth/Differentiation Transition
Authors: Hirose Shigenori , Mayanagi Taira , Pears Catherine , Amagai Aiko , Loomis William F. , Maeda Yasuo
Published: August 2005

When growth stops due to the depletion of nutrients,
Dictyostelium
cells rapidly turn off vegetative genes and start to express developmental genes. One of the early developmental genes,
dia1
, is adjacent to a vegetative gene,
impA
, on chromosome 4. An intergenic region of 654 bp separates the coding regions of these divergently transcribed genes. Constructs carrying the intergenic region expressed a reporter gene (green fluorescent protein gene) that replaced
impA
in growing cells and a reporter gene that replaced
dia1
(DsRed) during development. Deletion of a 112-bp region proximal to the transcriptional start site of
impA
resulted in complete lack of expression of both reporter genes during growth or development. At the other end of the intergenic region there are two copies of a motif that is also found in the
carA
regulatory region. Removing one copy of this repeat reduced
impA
expression twofold. Removing the second copy had no further consequences. Removing the central portion of the intergenic region resulted in high levels of expression of
dia1
in growing cells, indicating that this region contains a sequence involved in repression during the vegetative stage. Gel shift experiments showed that a nuclear protein present in growing cells recognizes the sequence GAAGTTCTAATTGATTGAAG found in this region. This DNA binding activity is lost within the first 4 h of development. Different nuclear proteins were found to recognize the repeated sequence proximal to
dia1
. One of these became prevalent after 4 h of development. Together these regulatory components at least partially account for this aspect of the growth-to-differentiation transition.
Evaluation of the expansion attained to date by concrete affected by alkali–silica reaction. Part III: Application to existing structures
Authors: Bérubé Marc-André , Smaoui Nizar , Fournier Benoit , Bissonnette Benoit , Durand Benoit
Published: August 2005

The expansion attained by a concrete affected by alkali-silica reaction (ASR) is an important parameter in the evaluation of the corresponding structure. In part I, relationships were established in the laboratory between the ASR expansion and the stiffness damage test (SDT), the damage rating index (DRI), and the cumulated width of cracks observed at the surface of concrete specimens made with various types of reactive aggregates. In part II, these relationships were verified in the case of specimens made in laboratory but exposed outdoors. In part III, the aforementioned methods were applied to three ASR-affected structures. The measurement of crack widths at the surface of the affected members allowed a rather good estimation of the concrete expansion, provided the measurements were taken on the most severely exposed sections of these members. The DRI did not allow differentiating the most visually and mechanically affected concretes from the least affected concretes. The SDT proved to be the most interesting method to date for evaluating the expansion of ASR-affected concrete; however, it seemed to underestimate the expansion of the prestressed concrete members investigated.Key words: aggregates, alkali–silica reaction, concrete, petrography, expansion, stiffness, cracking.
Improving decision quality: a risk-based go/no-go decision for buildoperatetransfer (BOT) projects
Authors: Ock Jong H , Han Seung H , Park Hyung K , Diekmann James E
Published: August 2005

The buildoperatetransfer (BOT) mechanism is used worldwide to promote diverse infrastructure projects. Success in BOT projects mainly depends on selecting the right project to promote. The right project selection initiates from identifying a presumably viable project to pursue at the early project initiation process. When deciding on a prospective project to pursue, developers in many cases rely on their judgment, intuition, or rules of thumb rather than analytic evaluation of the complex BOT characteristics and specific project conditions. It is expected that they will improve the quality of their decisions if a methodical formalism is provided that can help systematically recognize (i) risk factors in the BOT project environment, (ii) the impact of these decisions on project feasibility, and (iii) strategic alternatives to enhance these decisions. The main objective of this research is to develop a risk-based, go/no-go decision model as the formalism, which consists of a decision process model and a decision variables relationship model. A numerical example is presented to demonstrate the computational procedures of the model. In an effort to validate the model, this research invites 60 test subjects and adopts convergent experimental studies.Key words: buildoperatetransfer, go/no-go decision, decision quality, multi-attribute decision-making, convergent validation.
Design of carbon fibre reinforced polymer post-tensioned masonry diaphragm retaining walls
Authors: Lissel S L , Shrive N G , Gilliland J
Published: August 2005

Two masonry diaphragm retaining walls were constructed on the University of Calgary campus and post-tensioned with carbon fibre reinforced polymer (CFRP) tendons. As these are the first masonry diaphragm walls post-tensioned with CFRP tendons outside of a laboratory, one objective in the design was to provide a wide margin of safety, especially concerning the effective, or sustained, prestressing force and losses. The tendons are unbonded, so guidance chairs were placed during construction to meet the requirements of the clauses expected in the next edition of the Canadian masonry design code. Research has shown that the strength of masonry to resist shear in the webs is enhanced by the normal stress induced by post-tensioning, so this was used in the design. The webs of the walls interlock with the flanges, imposing restrictions on the spacing of the webs. A centre-to-centre spacing of 500  mm was selected, with one tendon per cavity. The design of the walls and capping beams is detailed, and the construction sequence and monitoring program are described briefly. Key words: post-tensioning, masonry, retaining walls, design, FRP tendons, corrosion free
Tensile strength of bolted ring-type splices of solid round leg members of guyed communication towers
Authors: Kumalasari Cindy , Shen Lihong , Madugula Murty K.S , Ghrib Faouzi
Published: August 2005

Bolted ring-type splices are very common in guyed communication towers using solid round legs 65 mm in diameter or smaller, but there is no guidance provided in either the Canadian Institute of Steel Construction Handbook of steel construction or the American Institute of Steel Construction Manual of steel construction for the design of such splices. Eighteen ring-type splices (three groups of six specimens each) were tested and experimental failure loads were determined. Based on the test results, it is concluded that it is unsafe to ignore the eccentricity of the splice. It is suggested that the load at first yield be conservatively taken as the strength of the splice. A simplified design method is proposed that takes into account the eccentricity of the splice, and the results from the proposed method agree closely with the experimental values.Key words: eccentricity of splice, guyed towers, ring-type splice, solid round legs, tensile strength.
Methyl-CpG-binding proteins in cancer: blaming the DNA methylation messenger
Authors: Ballestar Esteban , Esteller Manel
Published: August 2005

In recent years, epigenetic alterations have come to prominence in cancer research. In particular, hypermethylation of CpG islands located in the promoter regions of tumor-suppressor genes is now firmly established as an important mechanism for gene inactivation in cancer. One of the most remarkable achievements in the field has been the identification of the methyl-CpG-binding domain family of proteins, which provide mechanistic links between specific patterns of DNA methylation and histone modifications. Although many of the current data indicate that methyl-CpG-binding proteins play a key role in maintaining a transcriptionally inactive state of methylated genes, MBD4 is also known to be involved in excision repair of T:G mismatches. The latter is a member of this family of proteins and appears to play a role in reducing mutations at 5-methylcytosine. This review examines the contribution of methyl-CpG-binding proteins in the epigenetic pathway of cancer.Key words: methyl-CpG-binding, MeCP2, DNA methylation, Rett syndrome, cancer epigenetics.
Causes and consequences of DNA hypomethylation in human cancer
Authors: Hoffmann Michèle J , Schulz Wolfgang A
Published: August 2005

While specific genes are hypermethylated in the genome of cancer cells, overall methylcytosine content is often decreased as a consequence of hypomethylation affecting many repetitive sequences. Hypomethylation is also observed at a number of single-copy genes. While global hypomethylation is highly prevalent across all cancer types, it often displays considerable specificity with regard to tumor type, tumor stage, and sequences affected. Following an overview of hypomethylation alterations in various cancers, this review focuses on 3 hypotheses. First, hypomethylation at a single-copy gene may occur as a 2-step process, in which selection for gene function follows upon random hypo methylation. In this fashion, hypomethylation facilitates the adaptation of cancer cells to the ever-changing tumor tissue microenvironment, particularly during metastasis. Second, the development of global hypomethylation is intimately linked to chromatin restructuring and nuclear disorganization in cancer cells, reflected in a large number of changes in histone-modifying enzymes and other chromatin regulators. Third, DNA hypomethylation may occur at least partly as a consequence of cell cycle deregulation disturbing the coordination between DNA replication and activity of DNA methyltransferases. Finally, because of their relation to tumor progression and metastasis, DNA hypomethylation markers may be particularly useful to classify cancer and predict their clinical course.Key words : chromatin regulator proteins, retrotransposon, metastasis, chromosomal instability, methyltransferase, ectopic expression.
Chromatin architecture and functions: the role(s) of poly(ADP-RIBOSE) polymerase and poly(ADPribosyl)ation of nuclear proteins
Authors: Faraone-Mennella Maria Rosaria
Published: August 2005

Epigenetic states that allow chromatin fidelity inheritance can be mediated by several factors. One of them, histone variants and their modifications (including acetylation, methylation, phosphorylation, poly(ADP-ribosyl)ation, and ubiquitylation) create distinct patterns of signals read by other proteins, and are strictly related to chromatin remodelling, which is necessary for the specific expression of a gene, and for DNA repair, recombination, and replication. In the framework of chromatin-controlling factors, the poly(ADP-ribosyl)ation of nuclear proteins, catalysed by poly(ADP-ribose)polymerases (PARPs), has been implicated in the regulation of both physiological and pathological events (gene expression/amplification, cellular division/differentiation, DNA replication, malignant transformation, and apoptotic cell death). The involvement of PARPs in this scenario has raised doubts about the epigenetic value of poly(ADP-ribosyl)ation, because it is generally activated after DNA damage. However, one emerging view suggests that both the product of this reaction, poly(ADP-ribose), and PARPs, particularly PARP 1, play a fundamental role in recruiting protein targets to specific sites and (or) in interacting physically with structural and regulatory factors, through highly reproducible and inheritable mechanisms, often independent of DNA breaks. The interplay of PARPs with protein factors, and the combinatorial effect of poly(ADPribosyl)ation with other post-translational modifications has shed new light on the potential and versatility of this dynamic reaction.Key words: chromatin, epigenetic, poly(ADP-ribose), PARP.
DNA break repair: refined rules of an already complicated game
Authors: Vidaković Melita , Poznanović Goran , Bode Juergen
Published: August 2005

Of the many types of DNA-damage repair, this review concentrates on the aspects of DNA single- and double-strand break repair. Originally considered to represent separate routes based on distinct enzymatic machineries, it has recently been shown that these pathways converge and are interlinked at a number of points. Poly(ADP-ribose) polymerase-1 (PARP-1) is a central player in this complicated game. We present new data and our view on the mechanisms by which PARP-1 is guided to its respective interaction partners to coordinate or participate in repair or apoptosis.Key words: DNA strand break repair (DSBR), non-homologous end joining (NHEJ), nuclear architecture, nuclear matrix, PARP-1.
MeCP2: the chromatin connection and beyond
Authors: Zlatanova Jordanka
Published: August 2005

Of the recently discovered group of proteins that interpret DNA methylation signals by preferentially associating with methylated CpG dinucleotides, the methyl-CpG-binding protein 2 (MeCP2) has attracted considerable attention in view of its ability to repress transcription. The interest in MeCP2 dramatically increased following the discovery of mutated forms of the protein in patients with Rett syndrome, a neurodevelopmental disease. A connection with carcino-genesis has also been established. This review attempts to bring together and critically discuss recently acquired information about the molecular biology of the protein and its mechanism of action. A careful overview of the literature reveals the complexity of its activity, which goes well beyond the recognized chromatin connections. Finally, the newly established facts concerning the connection of MeCP2 to human disease are presented. Key words: methyl-CpG-binding proteins, MeCP2, transcription repression, chromatin modification, Rett syndrome, cancer.
Electrochemical reactivation of granular activated carbon: pH dependence
Authors: Karimi-Jashni Ayoub , Narbaitz Roberto M
Published: August 2005

The objectives of this paper were to verify and to quantify the dependence of granular activated carbon (GAC) electrochemical reactivation efficiency on the extreme pH values that occur at the electrodes. Phenol-loaded GAC was reactivated using a bench-scale electrochemical reactor. The pH values in the cathode and anode compartments during reactivation were 12 and 2, respectively. The pH of the electrolyte controlled the reactivation efficiency, and cathodic reactivation efficiencies were about 30% higher at pH 12 than at pH 2. Cathodic reactivation was about 20% more efficient than the anodic reactivation. The cathode, the reducing electrode, generates OH– ions, which increase the local pH at the cathode. Reduced phenol adsorbability at high pH promotes desorption from previously loaded GAC, thus increasing the reactivation efficiency. Greater phenol desorption was observed at pH 12 when the GAC was subjected to a 50-mA current than in the absence of a current. Thus, electrochemical reactivation is more efficient than chemical reactivation. Key words: granular activated carbon, pH, electrochemical, regeneration, reactivation, adsorption, desorption, phenol, F-400.
Phylogenetic assessment of heterotrophic bacteria from a water distribution system using 16S rDNA sequencing
Authors: Tokajian Sima T , Hashwa Fuad A , Hancock Ian C , Zalloua Pierre A
Published: August 2005

Determination of a heterotrophic plate count (HPC) for drinking-water samples alone is not enough to assess possible health hazards associated with sudden changes in the bacterial count. Speciation is very crucial to determine whether the population includes pathogens and (or) opportunistic pathogens. Most of the isolates recovered from drinking water samples could not be allocated to a specific phylogenetic branch based on the use of conventional diagnostic methods. The present study had to use phylogenetic analysis, which was simplified by determining and using the first 500-bp sequence of the 16S rDNA, to successfully identify the type and species of bacteria found in the samples. Gram-positive bacteria α-, β-, and γ-Proteobacteria were found to be the major groups representing the heterotrophic bacteria in drinking water. The study also revealed that the presence of sphingomonads in drinking water supplies may be much more common than has been reported so far and thus further studies are merited. The intermittent mode of supply, mainly characterized by water stagnation and flow interruption associated possibly with biofilm detachment, raised the possibility that the studied bacterial populations in such systems represented organisms coming from 2 different niches, the biofilm and the water column.Key words: intermittent water supply, 16S rDNA, biofilm, water column.
Conjugation of tetanus toxoid with Salmonella typhimurium PTCC 1735 O-specific polysaccharide and its effects on production of opsonizing antibodies in a mouse model
Authors: Jazani Nima Hosseini , Worobec Elizabeth , Shahabi Shahram , Nejad Ghorban Behzadian
Published: August 2005

Serious enteric and extra-intestinal infections with Salmonella typhimurium are very common in many human populations. Phagocytosis is the main defense mechanism against this bacterium; however, the unique structure of S. typhimurium lipopolysaccharide (LPS) makes it resistant to opsonization by complement components. In the present study, the S. typhimurium LPS O-chain was purified and conjugated with tetanus toxoid and the effects of the conjugated vaccine (O-specific polysaccharide tetanus toxoid (O-SP-TT)) on induction of specific antibodies were investigated in a mouse model. In vitro assays measuring phagocytosis in the presence of opsonizing antibodies were performed. Three subcutaneous injections of the O-SP-TT conjugate conferred protection against the intraperitoneal challenge with S. typhimurium and the LD50 was greater for immunized animals than for controls. The mean number of ingested S. typhimirium / mouse peritoneal cell in the presence of sera obtained from immunized mice with purified O-chain, O-SP-TT conjugate, heat-killed bacteria, and negative control were 6.96, 14.24, 15.96, and 6.67, respectively. In summary, we developed an O-SP-TT conjugate that induced opsonizing antibodies that increased phagocytosis, as determined by in vitro assays. In addition, chemiluminescence results, an indicator of oxidative burst, indicated that peritoneal cells respond better to live S. typhimurium cells in the presence of sera obtained from O-SP-TT conjugate immunized mice.Key words: lipopolysaccharide, conjugate, S. typhimurium, vaccine.
Proteinase PI and lactococcin A genes are located on the largest plasmid inLactococcus lactissubsp.lactisbv. diacetylactis S50
Authors: Kojic Milan , Strahinic Ivana , Topisirovic Ljubisa
Published: August 2005

Lactococcus lactis subsp. lactis bv. diacetylactis S50 produces a lactococcin A-like bacteriocin named bacteriocin S50, and cell envelope-associated PI-type proteinase activity. This strain harbours 3 small size plasmids: pS6 (6.3 kb), pS7a (7.31 kb), and pS7b (7.27 kb). Plasmid curing using a combination of novobiocin treatment (10 µg·mL–1) and sublethal temperature (40 °C) resulted in a very low yield (0.17%) of Prt–, Bac–, Bacsderivatives, which retained all 3 small size resident plasmids. Pulsed-field gel electrophoresis of DNA isolated from the strain S50 and cured derivatives in combination with restriction enzyme analysis and DNA–DNA hybridization revealed that S50 contains 2 additional large plasmids: pS140 (140 kb) and pS80 (80 kb). Conjugation experiments using strain S50 as a donor and various lactococcal recipients resulted in Prt+, Bac+, Bacrtransconjugants. Analysis of these transconjugants strongly indicated that plasmid pS140 harbours the prt and bac genes encoding proteinase and bacteriocin production, and immunity to bacteriocin, since each Prt+, Bac+, Bacrtranconjugant contained pS140. Accordingly, none of the Prt–, Bac–, Bacstransconjugants contained this plasmid. pS140 was a self-transmissible conjugative plasmid regardless of the host lactococcal recipient used in the test. Frequency of conjugation of plasmid pS140 did not depend on either the donor or recipient strain.Key words: Lactococcus, plasmids, conjugation, bacteriocin, proteinase.
Comparison of 2 ultrafiltration systems for the concentration of seeded viruses from environmental waters
Authors: Olszewski John , Winona Linda , Oshima Kevin H
Published: August 2005

The use of ultrafiltration as a concentration method to recover viruses from environmental waters was investigated. Two ultrafiltration systems (hollow fiber and tangential flow) in a large- (100 L) and small-scale (2 L) configuration were able to recover greater than 50% of multiple viruses (bacteriophage PP7 and T1 and poliovirus type 2) from varying water turbidities (10157 nephelometric turbidity units (NTU)) simultaneously. Mean recoveries (n = 3) in ground and surface water by the large-scale hollow fiber ultrafiltration system (100 L) were comparable to recoveries observed in the small-scale system (2 L). Recovery of seeded viruses in highly turbid waters from small-scale tangential flow (2 L) (screen and open channel) and hollow fiber ultrafilters (2 L) (small pilot) were greater than 70%. Clogging occurred in the hollow fiber pencil module and when particulate concentrations exceeded 1.6 g/L and 5.5 g/L (dry mass) in the screen and open channel filters, respectively. The small pilot module was able to filter all concentrates without clogging. The small pilot hollow fiber ultrafilter was used to test recovery of seeded viruses from surface waters from different geographical regions in 10-L volumes. Recoveries >70% were observed from all locations.Key words: ultrafiltration, waterborne virus detection, viral concentration.
Growth rate and oxygen regulate the interactions of group BStreptococcuswith polarized respiratory epithelial cells
Authors: Johri Atul K , Patwardhan Vilas , Paoletti Lawrence C
Published: August 2005

We investigated growth conditions that regulate the ability of group B Streptococcus (GBS) to attach to, invade, and translocate through polarized human respiratory epithelial cells (RECs). GBS grown in a chemostat at a fast cell mass doubling time (td = 1.8 h), invaded RECs from both the apical and basolateral surfaces in higher numbers compared with those held at a td = 11 h. With the exception of adherence from the basolateral surface, GBS reached peak adherence to, invasion of, and translocation through RECs when held at the fast tdwith 15% dissolved oxygen compared with 0% dissolved oxygen. Growth rate and oxygen level strongly influence the interaction of GBS with polarized RECs and likely GBS pathogenicity.Key words: group B Streptococcus, oxygen, invasion, host–pathogen interactions, regulation, translocation.
Molecular analysis ofShigella boydiiO1 O-antigen gene cluster and its PCR typing
Authors: Tao Jiang , Wang Lei , Liu Dan , Li Yue , Bastin David A , Geng Yunqi , Feng Lu
Published: August 2005

Shigella is an important human pathogen and is closely related to Escherichia coli. O-antigen is the most variable part of the lipopolysaccharide on the cell surface of Gram-negative bacteria and plays an important role in pathogenicity. The O-antigen gene cluster of S. boydii O1 was sequenced. The putative genes encoding enzymes for rhamnose synthesis, transferases, O-unit flippase, and O-unit polymerase were identified on the basis of homology. The O-antigen gene clusters of S. boydii O1 and E. coli O149, which share the same O-antigen form, were found to have the same genes and organization by adjacent gene PCR assay. Two genes specific for S. boydii O1 and E. coli O149 were identified by PCR screening against E. coli- and Shigella-type strains of the 186 known O-antigen forms and 39 E. coli clinical isolates. A PCR sensitivity of 103to 104CFU/mL overnight culture of S. boydii O1 and E. coli O149 was obtained. S. boydii O1 and E. coli O149 were differentiated by PCR using lacZ- and cadA-based primers.Key words: O-antigen gene cluster, S. boydii O1, E. coli O149, molecular typing.
Real-time quantitative PCR for enteric adenovirus serotype 40 in environmental waters
Authors: Jiang Sunny , Dezfulian Hojabr , Chu Weiping
Published: August 2005

Adenoviruses 40 and 41 have been recognized as important etiological agents of gastroenteritis in children. A real-time PCR method (TaqMan® assay) was developed for rapid quantification of adenovirus 40 (Ad40) by amplifying an 88 bp sequence from the hexon gene. To establish a quantification standard curve, a 1090 bp hexon region of Ad40 was amplified and cloned into the pGEM®-T Vector. A direct correlation was observed between the fluorescence threshold cycle number (Ct) and the starting quantity of Ad40 hexon gene. The quantification was linear over 6-log units and the amplification efficiency averaged greater than 95%. Seeding studies using various environmental matrices (including sterile water, creek water, brackish estuarine water, ocean water, and secondary sewage effluent) suggest that this method is applicable to environmental samples. However, real-time PCR was sensitive to inhibitors present in the environmental samples. Lower efficiency of PCR amplification was found in secondary sewage effluent and creek waters. Application of the method to fecal contaminated waters successfully quantified the presence of Ad40. The sensitivity of the real-time PCR is comparable to the traditional nested PCR assay for environmental samples. In addition, the real-time PCR assay offers the advantage of speed and insensitivity to contamination during PCR set up. The real-time PCR assay developed in this study is suitable for quantitative determination of Ad40 in environmental samples and represents a considerable advancement in pathogen quantification in aquatic environments.Key words: adenovirus, real-time PCR, environmental waters, serotype 40.
The influence ofBacillus subtilisRB14-C on the development ofRhizoctonia solaniand indigenous microorganisms in the soil
Authors: Szczech Magdalena , Shoda Makoto
Published: August 2005

The effect of soil inoculation with an antagonistic strain Bacillus subtilis RB14-C on the development of Rhizoctonia solani and changes occurring in soil and rhizosphere microbial communities were studied. RB14-C was added to the soil as a water suspension of the cells or as a broth culture. Application of cell suspensions to non-planted soil reduced the number of culturable bacteria. The density of R. solani and the number of filamentous fungi were not significantly affected by RB14-C. A similar effect was observed in the rhizosphere of tomato plants growns in bacterized soil. Broth cultures of RB14-C suppressed R. solani 1 d after inoculation, but after 3 d there was no difference in the pathogen density between soil amended with broth culture and control soil. In microcosm studies, cell suspensions of RB14-C also did not inhibit growth of R. solani on filters buried in soil. However, an inhibitory effect was obtained when a broth culture of the bacterium was used. The effect of RB14-C on fungal biomass was also estimated by measurement of ergosterol concentration in soil. It was found that ergosterol was mostly derived from R. solani and that there were no significant differences in its content between untreated soil and soil treated with RB14-C. The results suggest that suppression of Rhizoctonia damping-off by B. subtilis RB14-C probably is not related to the reduction of the pathogen population in the soil.Key words: B. subtilis, R. solani, ergosterol, native microflora.
Effects of dopamine in isolated rat colon strips
Authors: Aguilar María J , Estañ Luis , Martínez-Mir Inocencia , Martínez-Abad Manuel , Rubio Elena , Morales-Olivas Francisco J
Published: August 2005

The aim of the present work is to investigate the effects of dopamine on isolated rat colon strips, and whether dopamine receptors are involved in these effects. Experiments on spontaneous motility and under potassium contraction were performed with dopamine and isoprenaline, both in the absence and presence of antagonists (distal colon strips, isotonic recording, Tyrode solution, 31 °C, 1 g of resting tension). At higher concentration (10–4mol/L), dopamine abolished spontaneous motility of the rat colon and this effect was not modified by antagonists. In isolated rat colon strips that were depolarized with potassium, dopamine produced concentration-dependent relaxation, without significant differences in reserpinized rats. Preincubation with sulpiride or Sch 23390, dopamine antagonists, did not modify the effects of dopamine. Propranolol shifted the concentration-response curve to the right, though in a noncompetitive manner. Prazosin and yohimbine (α-antagonists) did not modify the response to dopamine. Isoprenaline produced a concentration-dependent relaxant response to the KCl-induced contraction antagonized by propranolol, but not by prazosin, in a noncompetitive manner. In conclusion, dopamine exhibits a relaxant effect on the isolated rat colon, which is not mediated by specific dopamine receptors or α-adrenoceptors but it may be mediated by atypical β-adrenoceptors. Key words: dopamine, isolated rat colon, dopamine receptors.
Adaptation to a high protein, carbohydrate-free diet induces a marked reduction of fatty acid synthesis and lipogenic enzymes in rat adipose tissue that is rapidly reverted by a balanced diet
Authors: Brito S M.R.C , Moura M A.F , Kawashita N H , Festuccia W T.L , Garófalo M A.R , Kettelhut I C , Migliorini R H
Published: August 2005

We have previously shown that in vivo lipogenesis is markedly reduced in liver, carcass, and in 4 different depots of adipose tissue of rats adapted to a high protein, carbohydrate-free (HP) diet. In the present work, we investigate the activity of enzymes involved in lipogenesis in the epididymal adipose tissue (EPI) of rats adapted to an HP diet before and 12 h after a balanced diet was introduced. Rats fed an HP diet for 15 days showed a 60% reduction of EPI fatty acid synthesis in vivo that was accompanied by 45%–55% decreases in the activities of pyruvate dehydrogenase complex, ATP-citrate lyase, acetyl-CoA carboxylase, glucose-6-phosphate dehydrogenase, and malic enzyme. Reversion to a balanced diet for 12 h resulted in a normalization of in vivo EPI lipogenesis, and in a restoration of acetyl-CoA carboxylase activity to levels that did not differ significantly from control values. The activities of ATP-citrate lyase and pyruvate dehydrogenase complex increased to about 75%–86% of control values, but the activities of glucose-6-phosphate dehydrogenase and malic enzyme remained unchanged 12 h after diet reversion. The data indicate that in rats, the adjustment of adipose tissue lipogenic activity is an important component of the metabolic adaptation to different nutritional conditions. Key words: lipogenesis, lipogenic enzymes, high protein diet, diet reversion.
A tubule cell model for ifosfamide nephrotoxicity
Authors: Aleksa Katarina , Halachmi Naomi , Ito Shinya , Koren Gideon
Published: August 2005

Mechanisms leading to ifosfamide (IF)-induced renal damage have not been fully elucidated. Recent work suggests that localized renal tubular metabolism of IF and the production of the nephrotoxic chloroacetaldehyde may lead to nephrotoxicity. Presently no pharmacological method to reduce IF nephrotoxicity has been identified. The objectives of this study were to establish a tubule cell model for IF nephrotoxicity, to verify whether renal proximal tubular cells have the necessary cytochrome P450 (CYP) enzymes to oxidize IF, and whether they can metabolize IF to chloroacetaldehyde. CYP3A, and 2B mRNA and protein were identified in LLCPK-1 cells. The cells metabolized the R- and S-IF enantiomers to their respective 2- and 3-dechloroethylifosfamide metabolites, by-products of chloroacetal dehyde formation. Metabolite production was both time and concentration-dependent. IF did not affect cell viability. In contrast, glutathione-depleted cells showed time and dose-dependent damage. The presence of the relevant CYP enzymes in renal tubular cells along with their ability to metabolize IF to its 2- and 3-dechloroethylifosfamide metabolites suggests that nephrotoxic damage may result from the localized production of chloroacetaldehyde. Glutathione is a major defence mechanism against IF toxicity, thus pharmacological methods for replenishing intracellular glutathione may be effective in modulating IF-induced nephrotoxicity. Key words: LLCPK-1, metabolism, ifosfamide, renal, CYP3A, CYP2B.
Functional expression and cellular localization of the Na+/H+exchanger Sod2 of the fission yeastSchizosaccharomycespombe
Authors: Fliegel Larry , Wiebe Christine , Chua Gordon , Young Paul G
Published: August 2005

In the fission yeast Schizosaccharomyces pombe, the Na+/H+exchanger, Sod2, plays a major role in the removal of excess intracellular sodium, and its disruption results in a sodium-sensitive phenotype. We examined the subcellular distribution and dynamics of Sod2 expression in S. pombe using a sod2-GFP fusion protein under the control of an attenuated version of the inducible nmt promoter. Sod2 was localized throughout the plasma membrane, the nuclear envelope, and some internal membrane systems. In exponentially growing cells, in which sod2-GFP was expressed and then the promoter turned-off, previously synthesized sod2-GFP was stable for long periods and found localized to the plasma membrane in the medial regions of the cell. It was not present at the actively growing cell ends. This suggests that these regions of the cell contain old plasma membrane protein vs. newly synthesized plasma membrane without Sod2 at the growing ends. Sod2 localization was not affected by salt stress. The results suggest that Sod2 is both a plasma membrane protein and is present in intracellular membranes. It is likely tethered within discrete regions of the plasma membrane and is not free to diffuse throughout the bilayer. Key words: Na+/H+exchanger, Schizosaccharomyces pombe, cation binding, salt tolerance.
Homocysteine-dependent cardiac remodeling and endothelial-myocyte coupling in a 2 kidney, 1 clip Goldblatt hypertension mouse model
Authors: Tyagi Neetu , Moshal Karni S , Lominadze David , Ovechkin Alexander V , Tyagi Suresh C
Published: August 2005

Accumulation of interstitial collagen (fibrosis) between the endothelium and myocytes is one of the hallmarks of cardiac failure in renovascular hypertension (RVH). Renal insufficiency increases plasma homocysteine (Hcy), and levels of peroxisome proliferator-activated receptor-γ (PPAR-γ) are inversely related to plasma Hcy levels. We hypothesize that in RVH, accumulation of collagen between the endothelium and myocytes leads to endothelial-myocyte disconnection and uncoupling, in part, by hyperhomocysteinemia. Furthermore, we hypothesize that Hcy increases reactive oxygen species, generates nitrotyrosine, activates latent matrix metalloproteinase, and decreases the levels of endothelial nitric oxide in response to antagonizing PPAR-γ. To create RVH in mice, the left renal artery was clipped with 0.4-mm sliver wire for the 2 kidney, 1 clip (2K1C) method. Sham surgery was used as a control. To induce PPAR-γ, 8 µg/mL ciglitazone (CZ) was administered to drinking water 2 days before surgery and continued for 4 weeks. Mice were grouped as 2K1C, sham, 2K1C+CZ, or sham+CZ (n = 6 in each group). Plasma Hcy increased 2-fold in the 2K1C-treated group (p < 0.05) as compared with the sham, and CZ had no effect on Hcy levels as compared to the 2K1C-treated group. Hcy binding in cardiac tissue homogenates decreased in the 2K1C-treated group but was substantially higher in the CZ-treated group. Cardiac reactive oxygen species levels were increased and endothelial nitric oxide were decreased in the 2K1C-treated group. Matrix metalloproteinase-2 and -9 activities were increased in the 2K1C-treated group compared with the control. Levels of cardiac inhibitor of metallopoteinase were decreased, whereas there was no change in tissue inhibitor of metalloproteinase-1 expression in the 2K1C-treated group vs. the sham-treated group. Collagen and nitrotyrosine levels were increased in the 2K1C-treated group, but mice treated with CZ showed lower levels comparatively. Cardiac transferase deoxyuridine nick-end labeling-positive cells were increased, and muscle cells were impaired in the 2K1C-treated mice vs. the sham-control mice. This was associated with decreased acetylcholine and bradykinin responses, which suggests endothelial-myocyte uncoupling in 2K1C-treated mice. Our results suggest that fibrosis between the endothelium and myocytes leads to an endothelial-myocyte disconnection and uncoupling by Hcy accumulation secondary to increased reactive oxygen species, nitrotyrosine, matrix metalloproteinase, and decreased endothelial nitric oxide in response to antagonizing PPAR-γ. Key words: ECM, collagen, elastin, cystathione β synthase, nitric oxide, arteriosclerosis, renal mechanism.
Effect of various antagonists on theChanna striatusfillet extract antinociception in mice
Authors: Zakaria Z A , Sulaiman M R , Jais A M. Mat , Somchit M N
Published: August 2005

The effects of an aqueous supernatant of haruan (ASH) (Channa striatus) fillet extract on various antinociception receptor system activities were examined using a mouse abdominal-constriction model. Mice that were pretreated with distilled water, s.c., followed 10 min later by administration of 25%, 50%, and 100% concentration ASH, s.c., produced a significant concentration-dependent antinociceptive activity (p < 0.001). Pretreatment with naloxone (0.3, 1.0, and 3.0 mg/kg body mass), 10 min before ASH administration, failed to block the extract antinociception. Pretreatment of the 100% concentration ASH with mecamylamine (5 mg/kg), pindolol (10 mg/kg), and haloperidol (1 mg/kg) also did not cause any significant change in its antinociception. However, pretreatment with atropine (5 mg/kg), bicuculline (10 mg/kg), phenoxybenzamine (10mg/kg), and methysergide (5 mg/kg) were found to reverse ASH antinociception. Based on the above findings, the ASH is suggested to contain different types of bioactive compounds that act synergistically on muscarinic, GABAA, α-adrenergic, and serotonergic receptor systems to produce the observed antinocicep tion. Key words: Haruan (Channa striatus), antinociceptive, writhing test, receptor systems
A field assessment of the SpalingerHobbs mechanistic foraging model: free-ranging moose in winter
Authors: Nordengren C , Ball John P
Published: August 2005

The mechanistic foraging models introduced by Spalinger and Hobbs in 1992 have been very influential in studies of herbivory at a variety of scales. However, almost no field study has evaluated whether the assumption regarding invariability of parameters with time holds for large herbivores with long foraging bouts, and most studies have obtained the model parameters from very short trials. We used free-ranging moose, Alces alces (L., 1758), to test this assumption of invariability and to compare intake calculated by the SpalingerHobbs model using parameters obtained from 10-min trials with intake calculated using data obtained from entire bouts. Our results revealed that the invariance assumption was not fully met: moose increased bite and chew rates and took smaller bites the longer a bite or chew sequence lasted, which resulted in declining intake rates. As a result, the original model misestimated intake by more than double for mountain birch (Betula pubescens ssp. czerepanovii (Orlova) Hämet-Ahti) and by up to 23% for willow (Salix spp.). Compared with data from entire foraging bouts, parameters derived from only the first 10 min of a bout overestimated intake of mountain birch by 31% and underestimated intake of willow by up to 24%. Our results suggest that for herbivores with long foraging bouts, one could modify the model to allow some parameters to vary with time but, more simply, one should parameterize the model using data from entire foraging bouts.
Ammonia tolerance in the slender lungfish (Protopterus dolloi): the importance of environmental acidification
Authors: Wood Chris M , Walsh Patrick J , Chew Shit F , Ip Yuen K
Published: August 2005

Protopterus dolloi Boulenger, 1900 is an obligate air-breather and exhibits ammoniotely (88% ammonia-N excretion, 12% urea-N excretion) under normal aquatic conditions, but tolerates 7 days of exposure to 30 mmol·L1NH4Cl, a treatment fatal to most other fish. Internal N accumulation is minimal and the subsequent washout of ammonia-N and urea-N after return to control conditions is negligible, indicating that N excretion continues and (or) that N metabolism is markedly depressed. Exposure to 30 mmol·L1NH4Cl in a closed system without aeration results in depressed urea-N excretion. The lungfish greatly acidifies the external water, a volume 25-fold greater than its own volume. The extent of this acidification increases with time. After several days, the external pH falls from about 7.0 to below 5.0 over a 24-h period, thereby markedly reducing the concentration of NH3(the form that diffuses across biological membranes). CO2excretion is partially responsible for this acidification, because vigorous water aeration reduces but does not eliminate the acidification, and urea-N excretion increases moderately. However, a substantial excretion of titratable acid (non-CO2acidity) also occurs. One exceptional lungfish was able to maintain its aerated environment at a stable pH of 3.7. Environmental acidification may be a less costly strategy for avoiding toxicity than detoxifying ammonia by increasing urea production.
Breeding vocalizations of the piping plover (Charadrius melodus): structure, diversity, and repertoire organization
Authors: Sung Ha-Cheol , Miller Edward H , Flemming Stephen P
Published: August 2005

We studied breeding vocalizations and the vocal repertoire of the endangered piping plover (Charadrius melodus Ord, 1824) to describe diversity of the species' non-learned vocalizations, provide a basis for comparative studies, and enable standardization of terminology and interpretation of vocal classes for management purposes. Adults have 14 call types and newly hatched chicks have three; these are underestimates of repertoire size because they represent breeding vocalizations only and are biased toward loud, easily recorded sounds. Vocalizations are structurally diverse: duration, ~10 ms to 1.5 s; peak frequency (adults), <900 to >3000 Hz; tonal to pulsed or noisy; narrow- to broad-band; and nonharmonic to harmonic. Vocalizations are higher in frequency in females than in males. High vocal diversity results from differential combination and sequencing of fairly simple acoustic attributes such as pulsing and frequency modulation, and from quantitative variation in such attributes. Homologies with other species of Charadriidae in acoustic traits of calls, call types, and organization (syntax) within calls and across call types are suggested. Acoustic characters at different organizational levels are highly conserved evolutionarily; hence, they seem to hold promise for phylogenetic analyses within the family.
Geographic variation in prevalence and parasitemia of Haemoproteus paruli in the cerulean warbler (Dendroica cerulea)
Authors: Gibb Christine E , Jones Jason , Girvan M Kate , Barg Jennifer J , Robertson Raleigh J
Published: August 2005

Although hostparasite interactions can affect the ecology and distribution of species, virtually nothing is known about range-wide variation in haematozoan levels in North American birds. We investigated haematozoan prevalence and parasitemia in 112 adult male cerulean warblers (Dendroica cerulea (Wilson, 1810)) in six populations throughout this species' breeding range. Thirty-six birds were infected with Haemoproteus paruli at low parasitemia (mean ± 1 SE, 6.18 ± 1.27 parasites/2000 erythrocytes). Prevalence did not differ between age classes, and there was no significant relationship between parasitism and body condition. However, prevalence and parasitemia were significantly higher in southern populations and further study is required to elucidate factors underlying regional differences in cerulean warbler haematozoan levels.
Differential expression sites of TGF-β isoforms in chicken limb buds during morphogenesis
Authors: Aramaki Shinya , Sato Fuminori , Soh Tomoki , Yamauchi Nobuhiko , Hattori Masa-aki
Published: August 2005

TGF-β gene is expressed at various developmental stages and its principle role may be an involvement in organogenesis. The present study was performed to investigate the temporal expression of these TGF-β isoforms in the developing limb of White Leghorn Chicken, Gallus gallus (L., 1758). TGF-β isoforms were expressed in the developing limb as revealed by whole-mount in situ hybridization, but each showed a different pattern of expression. TGF-β2 was the dominant isoform compared with the other two isoforms. TGF-β2 first appeared along the proximodistal axis of the limb at stage 24 and condensed at the tip at stage 26. At stages 2931, expression appeared in digits and then was extended to the interdigital spaces. A weak signal for TGF-β3 was first shown in the developing limb at stage 26, but there was no interdigital expression, unlike for TGF-β2. TGF-β4 was expressed in the developing limb at stage 26 and only in the interdigital spaces at stage 29. Reverse transcription  polymerase chain reaction analysis also showed that the transcript levels of TGF-β isoforms, especially TGF-β2, drastically increased at stage 29. These results suggest that TGF-β isoforms, with their patterns of expression, are specific regulatory factors that participate in limb development and digit morphogenesis.
PRIVATE-SECTOR PARTICIPATION IN THE WATER AND SANITATION SECTOR
Authors: Davis Jennifer
Published: August 2005

▪ Abstract  This review examines experience with private-sector participation (PSP) in the water supply and sanitation (W&S) sector. Common ideological, theoretical, and practical justifications for and objections to PSP in water and sanitation are presented. Review of empirical evidence suggests that where gains in efficiency, investment, and environmental stewardship have been realized through privatization, they have often been achieved through unpopular yet predictable strategies such as retrenchment and tariff increases. Challenges persist regarding ensuring access to and affordability of services for low-income households during privatization, and evidence suggests that PSP will not benefit the majority of the 1.2 billion people who lack access to improved water supply and live in the world's poorest countries. The challenging features of W&S economics, along with mounting public opposition to privatization and globalization in the sector, will likely reduce PSP in the sector over the short term, particularly where the private sector is expected to assume commercial risk as well as responsibility for capital investment in municipal W&S networks.
Molecular Genetics of Axis Formation in Zebrafish
Authors: Schier Alexander F. , Talbot William S.
Published: August 2005

The basic vertebrate body plan of the zebrafish embryo is established in the first 10 hours of development. This period is characterized by the formation of the anterior-posterior and dorsal-ventral axes, the development of the three germ layers, the specification of organ progenitors, and the complex morphogenetic movements of cells. During the past 10 years a combination of genetic, embryological, and molecular analyses has provided detailed insights into the mechanisms underlying this process. Maternal determinants control the expression of transcription factors and the location of signaling centers that pattern the blastula and gastrula. Bmp, Nodal, FGF, canonical Wnt, and retinoic acid signals generate positional information that leads to the restricted expression of transcription factors that control cell type specification. Noncanonical Wnt signaling is required for the morphogenetic movements during gastrulation. We review how the coordinated interplay of these molecules determines the fate and movement of embryonic cells.