bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reproduction Diversity of Enteromorpha prolifera
Authors: Lin Apeng , Shen Songdong , Wang Jianwei , Yan Binlun 
Published: April 2008

Abstract
Enteromorpha prolifera (Muell.) J. Agardh (Chlorophyta, Ulvophyceae), which is distributed widely in the inter‐tidal zone of the ocean, is one of the most common fouling green algae. However, the present understandings of the life history of E. prolifera have been insufficient to explain their seasonal abundances. Thus it is essential to investigate how many reproductive strategies are likely to contribute to the successful colonization and flourishing of the green alga. In the present study the reproduction diversity of E. prolifera was observed and studied systematically by culturing chopped tissues. Our results showed that there are in total seven pathways of reproduction for E. prolifera including sexual, asexual and vegetative reproduction. It was indicated that the variety of the reproductive ways and the large quantity of reproductive cells produced and released during the reproductive season are the two key factors that facilitate colonization of E. prolifera. The reproduction of the alga E. prolifera mainly depends on asexual methods. The results presented here contribute to increasing our understanding about how the opportunistic macroalgae successfully maintain colonization and excessive growth.
Inhibition of Ageratina adenophora on Spore Germination and Gametophyte Development of Macrothelypteris torresiana
Authors: Zhang Kai‐Mei , Shi Lei , Jiang Chuang‐Dao , Li Zhen‐Yu 
Published: April 2008

Abstract Allelopathy of Ageratina adenophora plays an important role in its invasion. However, we have little knowledge of its allelpathic effects on ferns. In Petri dish bioassays, the inhibitory potential of aqueous leachates from roots, stems and leaves of A. adenophora was studied on the spore germination and gametophyte development of Macrothelypteris torresiana. All leachates inhibited the spore germination and growth of the first rhizoid of M. torresiana and inhibitory effects increased with increasing leachate concentrations. Root leachates proved most inhibitory. Gametophyte rhizoids of M. torresiana treated with stem and leaf leachates of A. adenophora were erect, which was similar to those of the control. However, gametophyte rhizoids of M. torresiana treated with root leachates of A. adenophora were erect, but also curving or swollen. Moreover, curving and swollen rhizoids increased with increasing concentrations. As time went by, rhizoids treated with root leachates were not so curved and the swelling almost disappeared. Possible causes are discussed in the present study. The increasing concentrations of leaf leachates also delayed the stages of gametophyte development. With the treatment of root leachates, the delay was more obvious. Thus A. adenophora inhibited the spore germination and gametophyte development of M. torresiana and the root leachates were most inhibitory.
Modeling Size‐number Distributions of Seeds for Use in Soil Bank Studies
Authors: Casco Hugo , Dias Alexandra Soveral , Dias Luís Silva 
Published: April 2008

Abstract Knowledge of soil seed banks is essential to understand the dynamics of plant populations and communities and would greatly benefit from the integration of existing knowledge on ecological correlations of seed size and shape. The present study aims to establish a feasible and meaningful method to describe size‐number distributions of seeds in multi‐species situations. For that purpose, size‐number distributions of seeds with known length, width and thickness were determined by sequential sieving. The most appropriate combination of sieves and seeds dimensions was established, and the adequacy of the power function and the Weibull model to describe size‐number distributions of spherical, non‐spherical, and all seeds was investigated. We found that the geometric mean of seed length, width and thickness was the most adequate size estimator, providing shape‐independent measures of seeds volume directly related to sieves mesh side, and that both the power function and the Weibull model provide high quality descriptions of size‐number distributions of spherical, non‐spherical, and all seeds. We also found that, in spite of its slightly lower accuracy, the power function is, at this stage, a more trustworthy model to characterize size‐number distributions of seeds in soil banks because in some Weibull equations the estimates of the scale parameter were not acceptable.
Invasion Possibility and Potential Effects of Rhus typhina on Beijing Municipality
Authors: Wang Guangmei , Jiang Gaoming , Yu Shunli , Li Yinghao , Liu Hui 
Published: April 2008

Abstract
Rhus typhina, an alien species introduced from North America, was identified as a main afforestation species in Beijing municipality. However, its invasiveness is still at odds. To clarify this problem, we applied the North American Screening System and the Australian Screening System to preliminarily predict its invasion possibility. Both screening systems gave the same recommendation to “reject”. The geographical distribution was surveyed, with the population features of R. typhina against the native plant communities being assessed. With anthropogenic assistance, R. typhina has been scattered on almost all habitats from downtown to mountains, including roadsides, farmlands and protected areas. As a clonal shrub, R. typhina possessed a high spreading rate, varying from 6.3 m/3 years at sterile habitats to 6.7 m/3 years at fertile ones. Significantly lower species richness, individual density and diversity were observed in the R. typhina community than those of the native Vitex negundo Linn.var. heterophylla (Franch.) Rehd. community at both sterile and fertile habitats. Continual wide plantation of R. typhina may further foster its population expansion, which helps the species to overcome spatial isolation. The fact that each root fragment can develop into a new individual makes R. typhina very difficult to be eradicated once established. From a biological point of view, we believe that R. typhina is a plant invader in Beijing. We therefore suggest the government should remove the name of R. typhina from the main tree species list in afforesting Beijing.
Two New Triterpenoid Saponins from Gymnema sylvestre
Authors: Zhu Xu‐Min , Xie Ping , Di Ying‐Tong , Peng Shu‐Lin , Ding Li‐Sheng , Wang Ming‐Kui 
Published: April 2008

Abstract Two new oleanane‐type triterpenoid saponins, gymnemoside‐W1 and W2, together with seven known compounds were isolated from the leaves of Gymnema sylvestre R. Br. By means of spectral and chemical analysis, the structures of the new compounds were elucidated as 16 β‐hydroxyl olean‐12‐en‐3‐O‐[β‐D‐glucopyranosyl (1→6)‐β‐D‐glucopyranosyl]‐28‐O‐β‐D‐glucopyranoside(1) and 16 β,21 β,28‐trihydroxyl‐olean‐12‐ene‐3‐O‐glucoronopyranoside (2). The EtOH/H2O extracts of this plant were shown to be able to inhibit glucose absorption in rats.
Microbial‐based motor fuels: science and technology
Authors: Wackett Lawrence P. 
Published: April 2008

SummaryThe production of biofuels via microbial biotechnology is a very active field of research. A range of fuel molecule types are currently under consideration: alcohols, ethers, esters, isoprenes, alkenes and alkanes. At the present, the major alcohol biofuel is ethanol. The ethanol fermentation is an old technology. Ongoing efforts aim to increase yield and energy efficiency of ethanol production from biomass. n‐Butanol, another microbial fermentation product, is potentially superior to ethanol as a fuel but suffers from low yield and unwanted side‐products currently. In general, biodiesel fuels consist of fatty acid methyl esters in which the carbon derives from plants, not microbes. A new biodiesel product, called microdiesel, can be generated in engineered bacterial cells that condense ethanol with fatty acids. Perhaps the best fuel type to generate from biomass would be biohydrocarbons. Microbes are known to produce hydrocarbons such as isoprenes, long‐chain alkenes and alkanes. The biochemical mechanisms of microbial hydrocarbon biosynthesis are currently under study. Hydrocarbons and minimally oxygenated molecules may also be produced by hybrid chemical and biological processes. A broad interest in novel fuel molecules is also driving the development of new bioinformatics tools to facilitate biofuels research.
T‐DNA insertion, plasmid rescue and integration analysis in the model mycorrhizal fungusLaccaria bicolor
Authors: Kemppainen Minna , Duplessis Sebastien , Martin Francis , Pardo Alejandro G. 
Published: April 2008

SummaryEctomycorrhiza is a mutualistic symbiosis formed between fine roots of trees and the mycelium of soil fungi. This symbiosis plays a key role in forest ecosystems for the mineral nutrition of trees and the biology of the fungal communities associated. The characterization of genes involved in developmental and metabolic processes is important to understand the complex interactions that control the ectomycorrhizal symbiosis.Agrobacterium‐mediated gene transfer (AMT) in fungi is currently opening a new era for fungal research. As whole genome sequences of several fungi are being released studies about T‐DNA integration patterns are needed in order to understand the integration mechanisms involved and to evaluate the AMT as an insertional mutagenesis tool for different fungal species. The first genome sequence of a mycorrhizal fungus, the basidiomyceteLaccaria bicolor, became public in July 2006. Release ofLaccariagenome sequence and the availability of AMT makes this fungus an excellent model for functional genomic studies in ectomycorrhizal research. No data on the integration pattern inLaccariagenome were available, thus we optimized a plasmid rescue approach for this fungus. To this end the transformation vector (pHg/pBSk) was constructed allowing the rescue of the T‐DNA right border (RB)–genomic DNA junctions inEscherichia coli. Fifty‐oneAgrobacterium‐transformed fungal strains, picked up at random from a larger collection of T‐DNA tagged strains (about 500), were analysed. Sixty‐nine per cent were successfully rescued for the RB of which 87% were resolved for genomic integration sequences. Our results demonstrate that the plasmid rescue approach can be used for resolving T‐DNA integration sites inLaccaria. The RB was well conserved during transformation of this fungus and the integration analysis showed no clear sequence homology between different genomic sites. Neither obvious sequence similarities were found between these sites and the T‐DNA borders indicating non‐homologous integration of the transgenes. Majority (75%) of the integrations were located in predicted genes.Agrobacterium‐mediated gene transfer is a powerful tool that can be used for functional gene studies inLaccariaand will be helpful along with plasmid rescue in searching for relevant fungal genes involved in the symbiotic process.
The Intersecting Roles of Consumer and Producer: A Critical Perspective on Co‐production, Co‐creation and Prosumption
Authors: Humphreys Ashlee , Grayson Kent 
Published: April 2008

AbstractThe terms ‘co‐creation’, ‘co‐production’, and ‘prosumption’ refer to situations in which consumers collaborate with companies or with other consumers to produce things of value. These situations sometimes appear to blur the traditional roles of ‘producer’ and ‘consumer’. Building on Marx's distinction between ‘use value’ and ‘exchange value’, we argue that, when consumers perform tasks normally handled by the company, this does not necessarily represent a fundamental change in exchange roles or economic organization. We then argue that, when individuals who are traditionally defined as ‘consumers’ produce exchange value for companies, this does represent a fundamental change.
The efficacy of ursodeoxycholic acid and bezafibrate combination therapy for primary biliary cirrhosis: A prospective, multicenter study
Authors: Iwasaki Shinji , Ohira Hiromasa , Nishiguchi Shuhei , Zeniya Mikio , Kaneko Shuichi , Onji Morikazu , Ishibashi Hiromi , Sakaida Isao , Kuriyama Shigeki , Ichida Takafumi , Onishi Saburo , Toda Gotaro ,   Study Group of Intractable Liver Diseases for Research on a Specific Disease, Health Science Research Grant, Ministry of Health, Labour and Welfare of Japan
Published: April 2008

Aim:  Treatment with ursodeoxycholic acid (UDCA) improves the survival of stage I and II primary biliary cirrhosis (PBC) patients. However, new therapeutic options are needed for patients who are refractory to UDCA and for those whose disease is at an advanced stage. Bezafibrate could be useful in PBC treatment, since it increases phospholipid output into the bile and reduces the cytotoxicity of hydrophobic bile acids, which are increased with cholestasis.Methods:  We conducted two prospective, multicenter randomized open studies in non‐cirrhotic patients with PBC to evaluate the efficacy of bezafibrate. One study compared UDCA and bezafibrate monotherapy (study 1: 45 patients [37 females], mean age 55.9 years), and the other evaluated the addition of bezafibrate to patients who were refractory to UDCA (study 2: 21 patients [18 females], mean age 54.1 years).Results:  Study 1 demonstrated that bezafibrate monotherapy was as effective as UDCA and study 2 revealed that bezafibrate combined with UDCA was effective in improving and maintaining biliary enzymes where the ineffectiveness of long‐term treatment with UDCA was confirmed.Conclusion:  This multicenter, randomized, open study revealed that combination therapy of bezafibrate and UDCA improved biliary enzymes in non‐cirrhotic Japanese patients with PBC refractory to UDCA. Further studies are needed to evaluate whether combination therapy improves histological staging and prognosis.
Flexure Pivot Tilting Pad Hybrid Gas Bearings: Operation With Worn
Clearances and Two Load-Pad Configurations
Authors: San Andrés Luis , Ryu Keun 
Published: April 2008

Abstract
Gas film bearings enable the successful deployment of high-speed microturbomachinery. Foil bearings are in use; however, cost and lack of calibrated predictive tools prevent their widespread application. Other types of bearing configurations, simpler to manufacture and fully engineered, are favored by commercial turbomachinery manufacturers. Externally pressurized tilting pad bearings offer a sound solution for stable rotor support. This paper reports measurements of the rotordynamic response of a rigid rotor, 0.825kg and 28.6mm in diameter, supported on flexure pivot tilting pad hybrid gas bearings. The tests are performed for various imbalances, increasing supply pressures, and under load-on-pad (LOP) and load-between-pad (LBP) configurations. Presently, the initial condition of the test bearings shows sustained wear and dissimilar pad clearances after extensive testing reported earlier, (Zhu, X., and San Andrés, L., 2007, “Rotordynamic Performance of Flexure Pivot Hydrostatic Gas Bearings for Oil-Free Turbomachinery,” ASME J. Eng. Gas Turbines Power, 129, pp. 1020–1027). In the current measurements, there are no noticeable differences in rotor responses for both LOP and LBP configurations due to the light-weight rotor, i.e., small static load acting on each bearing. External pressurization into the bearings increases their direct stiffnesses and reduces their damping, while raising the system critical speeds with a notable reduction in modal damping ratios. The rotor supported on the worn bearings shows an ∼10% drop in first critical speeds and roughly similar modal damping than when tested with pristine bearings. Pressurization into the bearings leads to large times for rotor deceleration, thus demonstrating the little viscous drag typical of gas bearings. Rotor deceleration tests with manually controlled supply pressures eliminate the passage through critical speeds, thus paving a path for rotordynamic performance without large amplitude motions over extended regions of shaft speed. The rotordynamic analysis shows critical speeds and peak amplitudes of motion agreeing very well with the measurements. The synchronous rotor responses for increasing imbalances demonstrate the test system linearity. Superior stability and predictable performance of pressurized flexure pivot gas bearings can further their implementation in high performance oil-free microturbomachinery. More importantly, the measurements show the reliable performance of the worn bearings even when operating with enlarged and uneven clearances.
Active Air Control System Development Using Charge Air Integrated Manifold Engine Numerical Simulation (CAIMENS)
Authors: Grauer Diana K. , Chapman Kirby S. , Keshavarz Ali 
Published: April 2008

AbstractThis paper reports on an investigation into the transient, compressible flow physics that impact the trapped equivalence ratio. A comprehensive, variable geometry, multicylinder turbocharger-reciprocating engine computer simulation (T-RECS) has been developed to illustrate the effect of airflow imbalance on an engine. A new model, the charge air integrated manifold engine numerical simulation (CAIMENS), is a manifold flow model coupled with the T-RECS engine processor that uses an integrated set of fundamental principles to determine the crank angle-resolved pressure, temperature, burned and unburned mass fractions, and gas exchange rates for the cylinder. CAIMENS has the ability to show the transient impact of one cylinder firing on each successive cylinder. The pulsation model also describes the impact of manifold pressure drop on in-cylinder peak pressure and the pressure wave introduced to the intake manifold by uncovering the intake ports. CAIMENS provides the information necessary to quantify the impact of airflow imbalance, and allows for the visualization of the engine system before and after airflow correction. The model shows that not only does the manifold pressure drop have a significant impact on the in-cylinder peak pressure but it also has an impact on the pressure wave introduced to the intake manifold as the ports are opened. Also, each cylinder has a considerable impact on the airflow into each successive cylinder.
Both Oral Metronidazole and Oral Vancomycin Promote Persistent Overgrowth of Vancomycin-Resistant Enterococci during Treatment of
Clostridium difficile
-Associated Disease
Authors: Al-Nassir Wafa N. , Sethi Ajay K. , Li Yuejin , Pultz Michael J. , Riggs Michelle M. , Donskey Curtis J. 
Published: April 2008

ABSTRACT

For treatment of mild to moderate
Clostridium difficile
-associated disease (CDAD), oral metronidazole has been recommended as the preferred agent, in part due to concern that vancomycin may be more likely to promote colonization by vancomycin-resistant enterococci (VRE). We performed a prospective observational study to examine the effects of oral metronidazole or vancomycin treatment of CDAD on acquisition and concentration of VRE stool colonization. Before, during, and after 90 courses of CDAD therapy, stool samples were cultured for VRE, and the concentrations were quantified. Eighty-seven subjects (97%) had received antibiotics within the past month. For 56 treatment courses in which preexisting VRE colonization was present, metronidazole (
n
= 37 courses) and vancomycin (
n
= 19 courses), each promoted persistent VRE overgrowth during therapy, and the concentration decreased significantly in both groups by ∼2 weeks after completion of treatment (
P
<0.049). For 34 treatment courses in which baseline cultures were negative for VRE, new detection of VRE stool colonization occurred during 3 (14%) of the 22 courses of metronidazole and 1 (8%) of the 12 courses of vancomycin (
P
= 1.0). These results demonstrate that both oral metronidazole and oral vancomycin promote the overgrowth of VRE during treatment of CDAD. New CDAD treatments are needed that are less likely to disrupt the intestinal microflora and promote overgrowth of healthcare-associated pathogens.
A Naturally Occurring Proline-to-Alanine Amino Acid Change in Fks1p in
Candida parapsilosis
,
Candida orthopsilosis
, and
Candida metapsilosis
Accounts for Reduced Echinocandin Susceptibility
Authors: Garcia-Effron Guillermo , Katiyar Santosh K. , Park Steven , Edlind Thomas D. , Perlin David S. 
Published: April 2008

ABSTRACT

Candida parapsilosis
has emerged as a common cause of invasive fungal infection, especially in Latin America and in the neonatal setting.
C. parapsilosis
is part of a closely related group of organisms that includes the species
Candida orthopsilosis
and
Candida metapsilosis
. All three species show elevated MICs for the new echinocandin class drugs caspofungin, micafungin, and anidulafungin relative to other
Candida
species. Despite potential impacts on therapy, the mechanism behind this reduced echinocandin susceptibility has not been determined. In this report, we investigated the role of a naturally occurring Pro-to-Ala substitution at amino acid position 660 (P660A), immediately distal to the highly conserved hot spot 1 region of Fks1p, in the reduced-echinocandin-susceptibility phenotype. Kinetic inhibition studies demonstrated that glucan synthase from the
C. parapsilosis
group was 1 to 2 logs less sensitive to echinocandin drugs than the reference enzyme from
C. albicans
. Furthermore, clinical isolates of
C. albicans
and
C. glabrata
which harbor mutations at this equivalent position also showed comparable 2-log decreases in target enzyme sensitivity, which correlated with increased MICs. These mutations also resulted in 2.4- to 18.8-fold-reduced
V
max
values relative to those for the wild-type enzyme, consistent with kinetic parameters obtained for
C. parapsilosis
group enzymes. Finally, the importance of the P660A substitution for intrinsic resistance was confirmed by engineering an equivalent P647A mutation into Fks1p of
Saccharomyces cerevisiae
. The mutant glucan synthase displayed characteristic 2-log decreases in sensitivity to the echinocandin drugs. Overall, these data firmly indicate that a naturally occurring P660A substitution in Fks1p from the
C. parapsilosis
group accounts for the reduced susceptibility phenotype.
Prevalence of Serotype 19A
Streptococcus pneumoniae
among Isolates from U.S. Children in 2005-2006 and Activity of Faropenem
Authors: Critchley Ian A. , Jacobs Michael R. , Brown Steven D. , Traczewski Maria M. , Tillotson Glenn S. , Janjic Nebojsa 
Published: April 2008

ABSTRACT

Of 393 isolates of
Streptococcus pneumoniae
from U.S. children collected in 2005-2006, nonvaccine serotypes accounted for 89.1%, with serotype 19A the most prevalent, representing 30.5% of all isolates. The MIC
90
of faropenem against serotype 19A isolates was 1 μg/ml, compared to ≥8 μg/ml against amoxicillin/clavulanate, cefdinir, cefuroxime axetil, and azithromycin.