bluuebunny/crossref_metadata_2025_split huggingface dataset:
Connexin26 is responsible for anionic molecule permeability in the cochlea for intercellular signalling and metabolic communications
Authors: Zhao Hong‐Bo 
Published: May 2005

AbstractA gap junction is composed of two hemichannels and possesses a relatively large pore size (∼ 10–15 Å), allowing passage of ions and molecules up to 1 kDa. Here, we report that connexin hemichannels and gap junctions in the guinea pig cochlea had significant charge selectivity among permeating molecules. In coincubation with anionic and cationic fluorescent dyes, hemichannel permeability in isolated cochlear supporting cells showed significant charge selectivity; 31% of cells had only cationic dye influx and 6% of cells had only anionic dye influx. Charge‐selective influx contrary to dye size was also found, indicating charge as a dominant determinant in permeability. The cell–cell gap junctional permeability was consistent with hemichannel permeability and also showed strong charge selectivity; the permeation of anionic dyes was slower than that of cationic probes in the cochlear sensory epithelium. With a combination of immunofluorescent staining for connexin26 (Cx26) and Cx30, which are the predominant connexin isoforms in the cochlea, Cx26 was demonstrated to correlate with anionic permeability. The data indicated that cochlear gap junctions have strong charge selectivity in molecular permeability and metabolic communication. Cx26 mutation may induce specific, irreparable impairment in intercellular signalling and energy and nutrient supplies in the cochlea, causing cell degeneration and hearing loss, given that many important cell‐signalling and nutrient and energy molecules (e.g. IP3, ATP, cAMP and cGMP) are anions.
New understanding on phloem physiology and possible consequences for modelling long‐distance carbon transport
Authors: Minchin P. E. H. , Lacointe A. 
Published: May 2005

SummaryMost current models of assimilate carbohydrate partitioning are based on growth patterns observed under a range of experimental conditions, from which a set of empirical rules are derived to simulate partitioning. As a result, they are not good at extrapolating to other conditions; this requires a mechanistic approach, which only transport‐resistance (TR) models currently provide. We examine an approach to incorporating recent progress in phloem physiology into the TR approach, which leads to a ‘minimalist’ Münch model of a branched system with competing sinks. In vivo whole‐plant measurements have demonstrated that C‐flow rates are dependent not only on the properties of the sink, but also on the properties of the whole transport system, and the detailed dynamics of this behaviour is mimicked by the proposed model. This model provides a sound theoretical framework for an unambiguous definition of sink and source strengths, with sink priority being an emergent property of the model. Further developments are proposed, some of which have already had limited application, to cope with the complexity of plants; the emphasis is on a modular approach, together with the importance of choosing the appropriate scale level for both structure and function. Whole‐plant experiments with in vivo measurement of the phloem dynamics will be needed to help with this choice.
Forest fragmentation effects on patch occupancy and population viability of herbaceous plant species
Authors: Honnay Olivier , Jacquemyn Hans , Bossuyt Beatrijs , Hermy Martin 
Published: May 2005

SummaryHabitat fragmentation is one of the major threats to species diversity. In this review, we discuss how the genetic and demographic structure of fragmented populations of herbaceous forest plant species is affected by increased genetic drift and inbreeding, reduced mate availability, altered interactions with pollinators, and changed environmental conditions through edge effects. Reported changes in population genetic and demographic structure of fragmented plant populations have, however, not resulted in large‐scale extinction of forest plants. The main reason for this is very likely the long‐term persistence of small and isolated forest plant populations due to prolonged clonal growth and long generation times. Consequently, the persistence of small forest plant populations in a changing landscape may have resulted in an extinction debt, that is, in a distribution of forest plant species reflecting the historical landscape configuration rather than the present one. In some cases, fragmentation appears to affect ecosystem integrity rather than short‐term population viability due to the opposition of different fragmentation‐induced ecological effects. We finally discuss extinction and colonization dynamics of forest plant species at the regional scale and suggest that the use of the metapopulation concept, both because of its heuristic power and conservation applications, may be fruitful.ContentsSummary723IIntroduction724IIForest plant diversity in a historical perspective724IIIAn ecological profile of forest plant species725IVHabitat fragmentation and population viability726VEvidence of community composition changes due to habitat fragmentation?730VIAdding a regional dimension: forest plant species and metapopulation dynamics731VIIConclusions732Acknowledgements733References734
Impacts of parasitic plants on natural communities
Authors: Press Malcolm C. , Phoenix Gareth K. 
Published: May 2005

SummaryParasitic plants have profound effects on the ecosystems in which they occur. They are represented by some 4000 species and can be found in most major biomes. They acquire some or all of their water, carbon and nutrients via the vascular tissue of the host's roots or shoots. Parasitism has major impacts on host growth, allometry and reproduction, which lead to changes in competitive balances between host and nonhost species and therefore affect community structure, vegetation zonation and population dynamics. Impacts on hosts may further affect herbivores, pollinators and seed vectors, and the behaviour and diversity of these is often closely linked to the presence and abundance of parasitic plants. Parasitic plants can therefore be considered as keystone species. Community impacts are mediated by the host range of the parasite (the diversity of species that can potentially act as hosts) and by their preference and selection of particular host species. Parasitic plants can also alter the physical environment around them – including soil water and nutrients, atmospheric CO2and temperature – and so may also be considered as ecosystem engineers. Such impacts can have further consequences in altering the resource supply to and behaviour of other organisms within parasitic plant communities.ContentsSummary737I.Introduction738II.Parasitism: direct consequences738III.Dynamics of parasite–host interactions: host range, preference and selection738IV.Impacts of parasitic plants on the plant community739V.Impacts of the plant community on parasite populations741VI.Impacts of the parasite on other trophic levels742VII.Impacts of the parasite on the abiotic environment747VIII.Concluding remarks748References748
Do Bank Relationships Affect the Firm's Underwriter Choice in the Corporate‐Bond Underwriting Market?
Authors: YASUDA AYAKO 
Published: May 2005

ABSTRACTThis paper studies the effect of bank relationships on underwriter choice in the U.S. corporate‐bond underwriting market following the 1989 commercial‐bank entry. I find that bank relationships have positive and significant effects on a firm's underwriter choice,over and abovetheir effects on fees. This result is sharply stronger for junk‐bond issuers and first‐time issuers. I also find that there is a significant fee discount when there are relationships between firms and commercial banks. Finally, I find that serving as arranger of past loan transactions has the strongest effect on underwriter choice, whereas serving merely as participant has no effect.
Currency Returns, Intrinsic Value, and Institutional‐Investor Flows
Authors: FROOT KENNETH A. , RAMADORAI TARUN 
Published: May 2005

ABSTRACTWe decompose currency returns into (permanent) intrinsic‐value shocks and (transitory) expected‐return shocks. We explore interactions between these shocks, currency returns, and institutional‐investor currency flows. Intrinsic‐value shocks are: dwarfed by expected‐return shocks (yet currency returns overreact to them); unrelated to flows (although expected‐return shocks correlate with flows); and related positively to forecasted cumulated‐interest differentials. These results suggest flows are related to short‐term currency returns, while fundamentals better explain long‐term returns and values. They also rationalize the long‐observed poor performance of exchange‐rate models: by ignoring the distinction between permanent and transitory exchange‐rate changes, prior tests obscure the connection between currencies and fundamentals.
What Determines the Domestic Bias and Foreign Bias? Evidence from Mutual Fund Equity Allocations Worldwide
Authors: CHAN KALOK , COVRIG VICENTIU , NG LILIAN 
Published: May 2005

ABSTRACTWe examine how mutual funds from 26 developed and developing countries allocate their investment between domestic and foreign equity markets and what factors determine their asset allocations worldwide. We find robust evidence that these funds, in aggregate, allocate a disproportionately larger fraction of investment to domestic stocks. Results indicate that the stock market development and familiarity variables have significant, but asymmetric, effects on the domestic bias (domestic investors overweighting the local markets) and foreign bias (foreign investors under or overweighting the overseas markets), and that economic development, capital controls, and withholding tax variables have significant effects only on the foreign bias.
Predictive Value of Early Atrial Tachyarrhythmias Recurrence After Circumferential Anatomical Pulmonary Vein Ablation
Authors: BERTAGLIA EMANUELE , STABILE GIUSEPPE , SENATORE GAETANO , ZOPPO FRANCO , TURCO PIETRO , AMELLONE CLAUDIA , DE SIMONE ANTONIO , FAZZARI MASSIMO , PASCOTTO PIETRO 
Published: May 2005

Objective: Radiofrequency (RF) ablation at the ostia of the pulmonary veins (PVs) to cure atrial fibrillation (AF) is often followed by early AF recurrence. The aims of this study were to determine the rate of early atrial tachyarrhythmia as recurrence after circumferential anatomical PV ablation; to evaluate whether the early recurrence of atrial tachyarrhythmias correlates with the long‐term outcome of ablation; and to identify the predictors of early atrial tachyarrhythmias relapse.
Methods: We studied 143 consecutive patients who underwent circumferential anatomical PV ablation. We defined early atrial tachyarrhythmias relapse as the recurrence of atrial tachyarrhythmias during the first 3 months after RF ablation.
Results: After a mean follow‐up of 18.7 ± 7.2 months, 102/143 patients (71%) were deemed responders to ablation. Atrial tachyarrhythmias relapsed during the first 3 months of follow‐up in 65/143 (46%) patients. Patients without early atrial tachyarrhythmias relapse had a higher probability of long‐term clinical success than patients with early atrial tachyarrhythmias relapse (95% vs 43%, P < 0.0001). However, patients who relapsed within the first month had 45.5% probability of long‐term clinical success. On multivariate analysis, the presence of structural heart disease and the lack of a successful anatomical ablation of all targeted PV were significantly and independently correlated with early atrial tachyarrhythmias relapse.
Conclusion: A delayed cure may be expected in almost 50% of patients in whom atrial tachyarrhythmias relapses within the first month after circumferential anatomical PV ablation. The presence of structural heart disease and the lack of a successful anatomical ablation of all targeted PV predict early atrial tachyarrhythmias recurrence.
Feasibility of Using an Implantable System to Measure Thoracic Congestion in an Ambulatory Chronic Heart Failure Canine Model
Authors: WANG LI , LAHTINEN STUART , LENTZ LINNEA , RAKOW NANCY , KASZAS CAMERON , RUETZ LINDA , STYLOS LEE , OLSON WALTER H. 
Published: May 2005

Background: Noninvasive measures of impedance reflect alterations in thoracic fluid and pulmonary edema in acute animal and human studies.
Materials and Methods: We evaluated the feasibility of using an implantable impedance measuring device and cardiac lead system to monitor intrathoracic congestion in a pacing‐induced heart failure canine model. Three devices were implanted in each of five dogs: a modified pacemaker to measure impedance from a defibrillation lead implanted in the right ventricle; an implantable hemodynamic monitoring device to measure left ventricular end diastolic pressure (LVEDP) and a second pacemaker to deliver rapid (240 pulses per minute) ventricular pacing to induce heart failure.
Results: All five dogs developed severe heart failure after 3–4 weeks of rapid pacing and recovered following pacing termination. The LVEDP increased and impedance decreased during pacing‐induced heart failure and recovered after pacing cessation. At the end of pacing, there was a mean impedance reduction of 10.6 ± 8.3% and a mean LVEDP increase of 18.1 ± 4.5 mmHg compared to baseline. The impedance and LVEDP were inversely correlated (r =−0.41 to −0.85, all P < 0.05).
Conclusions: In the canine model, measurement of chronic intrathoracic impedance with an implantable system effectively revealed changes in thoracic congestion due to heart failure reflected by LVEDP. These data suggest that implantable device‐based impedance measurement merits further investigation as a tool to monitor the fluid status of heart failure patients.
Relationship between pH and Medium Dissolved Solids in Terms of Growth and Metabolism of Lactobacilli andSaccharomyces cerevisiaeduring Ethanol Production
Authors: Narendranath Neelakantam V. , Power Ronan 
Published: May 2005

ABSTRACTThe specific growth rates of four species of lactobacilli decreased linearly with increases in the concentration of dissolved solids (sugars) in liquid growth medium. This was most likely due to the osmotic stress exerted by the sugars on the bacteria. The reduction in growth rates corresponded to decreased lactic acid production. Medium pH was another factor studied. As the medium pH decreased from 5.5 to 4.0, there was a reduction in the specific growth rate of lactobacilli and a corresponding decrease in the lactic acid produced. In contrast, medium pH did not have any significant effect on the specific growth rate of yeast at any particular concentration of dissolved solids in the medium. However, medium pH had a significant (P< 0.001) effect on ethanol production. A medium pH of 5.5 resulted in maximal ethanol production in all media with different concentrations of dissolved solids. When the data were analyzed as a 4 (pH levels) by 4 (concentrations of dissolved solids) factorial experiment, there was no synergistic effect (P> 0.2923) observed between pH of the medium and concentration of dissolved solids of the medium in reducing bacterial growth and metabolism. The data suggest that reduction of initial medium pH to 4.0 for the control of lactobacilli during ethanol production is not a good practice as there is a reduction (P< 0.001) in the ethanol produced by the yeast at pH 4.0. Setting the mash (medium) with ≥30% (wt/vol) dissolved solids at a pH of 5.0 to 5.5 will minimize the effects of bacterial contamination and maximize ethanol production by yeast.
Quantification of Enterococci and Human Adenoviruses in Environmental Samples by Real-Time PCR
Authors: He Jian-Wen , Jiang Sunny 
Published: May 2005

ABSTRACT

Pathogenic bacteria and enteric viruses can be introduced into the environment via human waste discharge. Methods for rapid detection and quantification of human viruses and fecal indicator bacteria in water are urgently needed to prevent human exposure to pathogens through drinking and recreational waters. Here we describe the development of two real-time PCR methods to detect and quantify human adenoviruses and enterococci in environmental waters. For real-time quantification of enterococci, a set of primers and a probe targeting the 23S rRNA gene were used. The standard curve generated using
Enterococcus faecalis
genomic DNA was linear over a 7-log-dilution series. Serial dilutions of
E. faecalis
suspensions resulted in a lower limit of detection (LLD) of 5 CFU/reaction. To develop real-time PCR for adenoviruses, degenerate primers and a Taqman probe targeting a 163-bp region of the adenovirus hexon gene were designed to specifically amplify 14 different serotypes of human adenoviruses, including enteric adenovirus serotype 40 and 41. The standard curve generated was linear over a 5-log-dilution series, and the LLD was 100 PFU/reaction using serial dilutions of purified adenoviral particles of serotype 40. Both methods were optimized to be applicable to environmental samples. The real-time PCR methods showed a greater sensitivity in detection of adenoviruses in sewage samples than the viral plaque assay and in detection of enterococci in coastal waters than the bacterial culture method. However, enterococcus real-time PCR overestimated the number of bacteria in chlorinated sewage in comparison with the bacterial culture method. Overall, the ability via real-time PCR to detect enterococci and adenoviruses rapidly and quantitatively in the various environmental samples represents a considerable advancement and a great potential for environmental applications.
Deuterium-Resistant Algal Cell Line for D Labeling of Heterotrophs Expresses Enhanced Level of Hsp60 in D2O Medium
Authors: Unno Keiko , Hagima Naoko , Kishido Takahiro , Okada Shoji , Oku Naoto 
Published: May 2005

ABSTRACTFully deuterated components from autotrophic cell lysate are useful materials for labeling of heterotrophs with deuterium. To facilitate the faster production of deuterated algal lysate, we selected a mutantChlorellastrain that grows faster in heavy water than the wild type. The mutant DR-17 was found to have a higher level of Hsp60 and an elevated level of protein synthesis. We previously isolated a deuterium-resistant yeast cell line that was also found to express elevated level of Hsp70 (K. Unno, T. Kishido, M. Morioka, S. Okada, and N. Oku, Biol. Pharm. Bull.26:799-802, 2003). This suggests that the overexpression of heat shock proteins is required to compensate for the deuterium isotope effect.
Seasonal Response of Stream Biofilm Communities to Dissolved Organic Matter and Nutrient Enrichments
Authors: Olapade Ola A. , Leff Laura G. 
Published: May 2005

ABSTRACT

Dissolved organic matter (DOM) and inorganic nutrients may affect microbial communities in streams, but little is known about the impact of these factors on specific taxa within bacterial assemblages in biofilms. In this study, nutrient diffusing artificial substrates were used to examine bacterial responses to DOM (i.e., glucose, leaf leachate, and algal exudates) and inorganic nutrients (nitrate and phosphate singly and in combination). Artificial substrates were deployed for five seasons, from summer 2002 to summer 2003, in a northeastern Ohio stream. Differences were observed in the responses of bacterial taxa examined to various DOM and inorganic nutrient treatments, and the response patterns varied seasonally, indicating that resources that limit the bacterial communities change over time. Overall, the greatest responses were to labile, low-molecular-weight DOM (i.e., glucose) at times when chlorophyll
a
concentrations were low due to scouring during significant storm events. Different types of DOM and inorganic nutrients induced various responses among bacterial taxa in the biofilms examined, and these responses would not have been apparent if they were examined at the community level or if seasonal changes were not taken into account.
Production of Rhamnolipids by
Pseudomonas chlororaphis
, a Nonpathogenic Bacterium
Authors: Gunther Nereus W. , Nuñez Alberto , Fett William , Solaiman Daniel K. Y. 
Published: May 2005

ABSTRACT

Rhamnolipids, naturally occurring biosurfactants constructed of rhamnose sugar molecules and β-hydroxyalkanoic acids, have a wide range of potential commercial applications. In the course of a survey of 33 different bacterial isolates, we have identified, using a phenotypic assay for rhamnolipid production, a strain of the nonpathogenic bacterial species
Pseudomonas chlororaphis
that is capable of producing rhamnolipids. Rhamnolipid production by
P. chlororaphis
was achieved by growth at room temperature in static cultures of a mineral salts medium containing 2% glucose. We obtained yields of roughly 1 g/liter of rhamnolipids, an amount comparable to the production levels reported in
Pseudomonas aeruginosa
grown with glucose as the carbon source. The rhamnolipids produced by
P. chlororaphis
appear to be exclusively the mono-rhamnolipid form. The most prevalent molecular species had one monounsaturated hydroxy fatty acid of 12 carbons and one saturated hydroxy fatty acid of 10 carbons.
P. chlororaphis
, a nonpathogenic saprophyte of the soil, is currently employed as a biocontrol agent against certain types of plant fungal diseases. The pathogenic nature of all bacteria previously known to produce rhamnolipids has been a major obstacle to commercial production of rhamnolipids. The use of
P. chlororaphis
therefore greatly simplifies this matter by removing the need for containment systems and stringent separation processes in the production of rhamnolipids.
Nested PCR-Denaturing Gradient Gel Electrophoresis Approach To Determine the Diversity of Sulfate-Reducing Bacteria in Complex Microbial Communities
Authors: Dar Shabir A. , Kuenen J. Gijs , Muyzer Gerard 
Published: May 2005

ABSTRACT

Here, we describe a three-step nested-PCR-denaturing gradient gel electrophoresis (DGGE) strategy to detect sulfate-reducing bacteria (SRB) in complex microbial communities from industrial bioreactors. In the first step, the nearly complete 16S rRNA gene was amplified using bacterial primers. Subsequently, this product was used as a template in a second PCR with group-specific SRB primers. A third round of amplification was conducted to obtain fragments suitable for DGGE. The largest number of bands was observed in DGGE patterns of products obtained with primers specific for the
Desulfovibrio-Desulfomicrobium
group, indicating a large diversity of these SRBs. In addition, members of other phylogenetic SRB groups, i.e.,
Desulfotomaculum
,
Desulfobulbus
, and
Desulfococcus-Desulfonema-Desulfosarcina
, were detected. Bands corresponding to
Desulfobacterium
and
Desulfobacter
were not detected in the bioreactor samples. Comparative sequence analysis of excised DGGE bands revealed the identity of the community members. The developed three-step PCR-DGGE strategy is a welcome tool for studying the diversity of sulfate-reducing bacteria.