bluuebunny/crossref_metadata_2025 huggingface dataset:
Zygotic embryo development in Daucus carota
Authors: Lackie Sharon , Yeung Edward C.
Published: April 2008

After fertilization, the zygote divided unequally, giving rise to a larger basal cell and a smaller terminal cell. Derivatives from the basal cell gave rise to the suspensor and the terminal cell gave rise to the embryo proper. The suspensor usually consisted of a uniseriate file of 10–12 cells. However, additional anticlinal and oblique divisions resulted in some suspensors having more than one cell file. Cuticular substance was not present in the suspensor cell wall. The embryo proper was derived from the terminal four cells of the eight-celled embryo. The protoderm differentiated first, and subsequent to its formation cuticular substance could be detected in the outer tangential walls using the Nile red stain. This staining pattern intensified as the embryo matured. A defined cell lineage was not associated with tissue and meristem differentiation. Meristems began to form at the heart stage and became clearly defined at the late heart – early cotyledon stage. Keywords: cuticular material, Daucus carota, fluorescence, suspensor, zygotic embryogenesis.
Stomate and pollen content of lake surface sediments from across the tree line on the Taimyr Peninsula, Siberia
Authors: Clayden S. L. , Cwynar L. C. , MacDonald G. M.
Published: April 2008

Surface-sediment samples from 23 lakes on the Taimyr Peninsula were collected along a transect from tundra to forest and analyzed for their pollen and coniferous stomate content. Larix sibirica, the dominant tree in forest–tundra and forest vegetation zones, is poorly represented in the pollen spectra, never exceeding 8%. To examine the correspondence between the modern pollen rain and the vegetation zones of tundra, forest–tundra, and forest, a principal components analysis was applied to the pollen percentages. Betula and Alnus account for the greatest variance in the data set, and the set of tundra sites farthest north is distinct from the forest sites farthest south. Stomates of L. sibirica are present in all samples from sites where Larix trees are present, and some samples contained higher concentrations of stomates than pollen of Larix. Picea obovata stomates are found less consistently and less abundantly than Larix stomates.
A comparative study of the effects of the root endophytes Leptodontidium orchidicola and Phialocephala fortinii (Fungi Imperfecti) on the growth of some subalpine plants in culture
Authors: Fernando Analie A. , Currah Randolph S.
Published: April 2008

Resynthesis studies were done to determine the ecological role of Leptodontidium orchidicola, a dematiaceous hyphomycete commonly associated with roots of plants growing in cool and humus-rich soils. Results were compared with those of Phialocephala fortinii, another common root endophyte with similar cultural and vegetative characteristics. In axenic culture with Salix glauca seedlings, L. orchidicola caused a marked increase in host root length but also invaded the stele, causing extensive cellular lysis. Phialocephala fortinii formed a Hartig net and a thin, patchy mantle. In pot monocultures with Potentilla fruticosa, Dryas octopetala, S. glauca, and Picea glauca seedlings, the effects of four L. orchidicola strains on host dry weight were strain- and host-specific; the effects of Phialocephala fortinii were also host-specific. Leptodontidium orchidicola formed a range of symbiotic associations that could be considered mycorrhizal to parasitic, whereas the effects of Phialocephala fortinii suggest amensal, parasitic, or neutral association. In pot combination cultures, the Phialocephala fortinii – Potentilla fruticosa symbiosis resulted in a significant increase in shoot weight in contrast with the results of the same symbiosis in monoculture resynthesis. The resynthesis experiments demonstrated that the effects of both L. orchidicola and Phialocephala fortinii also vary according to cultural conditions. Keywords: Leptodontidium orchidicola, Phialocephala fortinii, Mycelium radicis atrovirens, fungus–plant symbiosis, subalpine plants.
Vesicular–arbuscular mycorrhizal associations of American ginseng (Panax quinquefolius) in commercial production
Authors: Whitbread Fraser , Peterson R. Larry , McGonigle Terry P.
Published: April 2008

Panax quinquefolius L. (American ginseng) roots collected from 1st year seedlings and 3-year-old plants on three commercial farms were colonized by vesicular–arbuscular mycorrhizal (VAM) fungi. Roots collected from ginseng plants in a managed maple–beech woodlot were also colonized by VAM fungi. Fungal hyphae entered roots either directly through root hairs or by forming appressoria on the surface of epidermal cells from which penetration hyphae formed. Hyphae colonized roots by passing intracellularly through cortical cells. Hyphal coils, from which arbuscular branches formed, were typical of the Paris-type of VAM association. The extent of colonization by hyphal coils and by arbuscules varied between 1-year-old and 3-year-old plants and among farms. The seasonal maxima for colonization differed among combinations of farms and plant age-classes in such a way as to suggest that a significant degree of the variability was due to characteristics of the individual seed beds. Over the season, we saw earlier development of hyphal coils that was only later exceeded by production of arbuscules; this pattern is consistent with the Paris-type morphology observed, in that arbuscule branches develop from hyphal coils. However, the speed at which arbuscules developed at some points in the season was so great that at those times the transition from newly formed hyphal coils to arbuscules must be extremely fast. Vesicles were rarely found in any root samples examined. Keywords: ginseng, Panax quinquefolius, vesicular–arbuscular mycorrhiza, commercial farms.
Effects of pollen competition on the reproductive performance in cucurbit hybrids (Cucurbitaceae): F1 and backcross generations
Authors: Quesada Mauricio , Stephenson Andrew G. , Winsor James A.
Published: April 2008

We examined the effect of pollen competition on the reproductive performance of Cucurbita F1 and backcross progeny while attempting to control for nongenetic maternal effects and nonrandom seed abortion as possible explanations for the data. We compared the vigor of F1 and backcross progeny produced from large and small pollen loads under field conditions. The results from both field studies indicated that the progeny produced from large pollen loads outperformed the progeny produced from small pollen loads for several measures of vigor. The F1 progeny produced from large pollen loads germinated faster, and produced 12% more staminate flowers and 9% more pistillate flowers than the progeny from the small pollen loads. Similarly, the backcross progeny produced from large pollen loads germinated faster, and produced 8% more pistillate flowers and 20% more fruits than the progeny from the small pollen loads. This study demonstrates a positive correlation between the size of the pollen load and the vigor of the resulting progeny under field conditions. Keywords: pollen competition, pollen performance, nonrandom fertilization, plant fitness, reproductive output.
Lichens and lichenicolous fungi of the Queen Charlotte Islands, British Columbia, Canada. 2. The Cladoniaceae
Authors: Brodo Irwin M. , Ahti Teuvo
Published: April 2008

The Queen Charlotte Islands, off the west coast of British Columbia and with a hypermoist, oceanic climate, has 44 taxa in the Cladoniaceae: 5 species and 1 forma of Cladina, and 34 species with 3 additional subspecies and 1 variety of Cladonia. Two species and one subspecies are described as new to science: Cladonia albonigra Brodo & Ahti, Cladonia schofieldii Ahti & Brodo, and Cladonia ecmocyna Leight. ssp. occidentalis Ahti. In addition, one new combination is made: Cladonia novochlorophaea (Sipman) Brodo & Ahti. Cladonia homosekekaica Nuno, although not part of the Queen Charlotte flora, is also described and discussed. Chemical variation in the Cladoniaceae is examined critically, and many taxa formerly recognized at the species or infraspecific levels are reduced to unnamed chemotypes. The following synonymies were made or confirmed: Cladina aberrans (Abbayes) Hale & W.L. Culb. =Cladina stellaris (Opiz) Brodo; Cladonia squamosa var. subsquamosa (Nyl. ex Leight.) Vain. =Cladonia squamosa Hoffm.; Cladonia pseudostellata Asahina =Cladonia uncialis (L.) F.H. Wigg.; Cladonia japonica Vain. =Cladonia crispata (Ach.) Flot.; Cladonia pseudorangiformis Asahina =Cladonia wainioi Saviez. A thamnolic acid chemotype of Cladonia bellidiflora (Ach.) Schaer. and a thamnolic and usnic acid containing chemotype of Cladonia umbricola Tønsberg & Ahti are common on the Charlottes. Cladonia singularis S. Hammer is reported as new to Canada based on a specimen from Vancouver Island. Cladonia macroptera Räsänen, Cladonia polydactyla (Flörke) Spreng., Cladonia pseudomacilenta Asahina, and Cladonia subsubulata Nyl. are excluded from the North American flora. Cladonia kanewskii Oksner is reported as new to Norway and Europe. Keywords: Cladina, Cladonia, Cladoniaceae, British Columbia.
Population size and genome size in fishes: a closer look
Authors: Gregory T. Ryan , Witt Jonathan D.S.
Published: April 2008

The several thousand-fold range in genome size among animals has remained a subject of active research and debate for more than half a century, but no satisfactory explanation has yet been provided. Many one-dimensional models have been postulated, but so far none has been successful in accounting for observed patterns in genome size diversity. The recent model based on differences in effective population size appeared to gain empirical support with a study of genome size and inferred effective population size in fishes, but there were several questionable aspects of the analysis. First, it was based on an assumption that microsatellite heterozygosity indicates long-term effective population size, whereas in actuality these markers evolve quickly and are sensitive to demographic events. Second, it included both ancient polyploids and non-polyploids, the former of which did not gain their current genome sizes through the accumulation of slightly deleterious mutations as required in the model. Third, the analysis neglected the tremendous influence that Pleistocene glaciation bottlenecks had on heterozygosities in freshwater (and far less so, marine) fishes. In sum, it is apparent that genomes reached their current sizes in most fishes long before contemporary microsatellite heterozygosities were shaped, and that ancient polyploidy rather than the accumulation of mildly deleterious transposon insertions in small populations is the dominant factor that has influenced the large end of the range of genome sizes among fishes.
Phenotypic characterization, genetic analysis, and molecular mapping of a new mutant gene for male sterility in rice
Authors: Zuo Ling , Li Shuangcheng , Chu Mingguang , Wang Shiquan , Deng Qiming , Ding Lei , Zhang Jing , Wen Yong , Zheng Aiping , Li Ping
Published: April 2008

xs1 is a male-sterile rice mutant derived from a spontaneous mutation. The floret of the mutant, consisting of 6 stamens and 1 pistil, looks the same as that of the wild type except that the filaments are long and thin and the anthers are withered in white transparence. It is confirmed that xs1 is a no-pollen type of male-sterile mutant, for no pollen grains can be stained with I2–KI solution and the anther locules are always hollow. Anther transverse sections indicate that the mutant microspores are abnormally condensed and agglomerated to form a deeply stained cluster at the late microspore stage, which results in cessation of the vacuolation process of microspores, and, therefore, the mutant forms no functional pollens for reproduction. Genetic analysis of 4 F2 populations and 3 BC1F1 populations revealed that the mutation is controlled by a single recessive gene, termed VR1 (Vacuolation retardation 1). Screening of 432 F2 mutant individuals derived from the cross of xs1 × G603 with simple sequence repeat markers revealed that VR1 is located between the molecular markers RM17411 and RM5030, at distances of 0.7 and 1.5 cM, respectively, on chromosome 4. VR1 is a new male fertility controlling gene located on chromosome 4 in rice.
Coagulation assisted membrane filtration to treat high strength wastewater from municipal solid waste anaerobic digesters
Authors: Xie Xin , Zhou Hongde , Chong Calvin , Holbein Bruce
Published: April 2008

Effluents from the anaerobic digestion of municipal solid wastes contain a variety of organic and inorganic components with a high concentration of nitrogen and phosphorous. The feasibility to treat these effluents prior to discharge or reuse was evaluated experimentally using membrane filtration coupled with coagulation pretreatment. Standard jar tests were conducted by varying alum doses and pH values. Both raw and coagulated wastewaters were then filtered using a submerged ultrafiltration apparatus at different sparging aeration rates and permeate fluxes. It was shown that coagulation reduced the membrane fouling rates due to the increase in particle sizes. Furthermore, the flocs formed from sweep coagulation had a better filterability than those from charge neutralization. However, coagulation pretreatment only moderately increased the removal efficiencies of organic matter from subsequent ultrafiltration because only a portion of oganic matter could be adsorbed and (or) co-precipitated on coagulated flocs.
GIS-based locational analysis of collection bins in municipal solid waste management systems
Authors: Vijay Ritesh , Gautam Ajay , Kalamdhad Ajay , Gupta Apurba , Devotta Sukumar
Published: April 2008

Solid waste management systems currently receive wide attention, from both economic and environmental planners, because of their complexity during coordination of various management strategies. The efficiency and cost effectiveness of route optimization and disposal site selection depend largely upon the appropriate placement of storage bins and their corresponding command area for waste contribution. The present paper illustrates a geographic information system (GIS) based algorithm for optimal location and number of storage bins, considering p-median constrained model, based on Indian guidelines for Municipal Solid Waste Rules. The algorithm also computes the contributing command area of solid waste to a particular bin, based on the shortest distance, with descending slope for ease in solid waste collection.
Characterization of anionic surfactant-induced toxicity in a primary effluent
Authors: Bradley C. , Bérubé P.R.
Published: April 2008

A simple and rapid analytical approach was developed that can be used to investigate the anionic surfactant-induced toxicity associated with the primary effluent from the Lions Gate wastewater treatment plant (North Vancouver, BC). Using this approach, the effluent was characterized on two occasions in terms of anionic surfactant concentration and anionic surfactant-induced toxicity. The results suggest that the concentration of anionic surfactants, measured as methylene blue active substances (MBAS), in the primary effluent increased throughout each day and was highest at night (11:30 p.m.). The toxicity, measured using Vibrio fischeri bioassays (i.e., MicroTox™), also increased throughout each day and was the highest at night. The high molecular weight fraction of anionic surfactants was identified as the most toxic fraction although it was present at the lowest concentration. The results of the present study suggest that the concentration of the high molecular weight fraction of anionic surfactants could be used as a good surrogate to easily and rapidly quanitfy the anionic surfactant-induced toxicity of the primary effluent.
In-well air sparging efficiency in remediating the aquifer of a petroleum refinery site
Authors: Aivalioti Maria V. , Gidarakos Evangelos L.
Published: April 2008

Air sparging represents an innovative groundwater remediation technology, which has been proved to be capable of restoring aquifers that have been polluted by volatile and (or) biodegradable contaminants, such as petroleum hydrocarbons. This paper presents the design, the installation, and the pulsed operation of an in-well air sparging system at the site of a Greek petroleum refinery. The geographical position, the hydrologeoly, and the contamination features of the chosen study area develop special conditions that, along with the fact that the existing refinery is still active, greatly determine the applicability and the effectiveness of the specific technology. The area that was used for the application of the technology covered almost 600 m2 and included five air injection wells and four additional monitoring wells. The pulsed operation of the installed system lasted about 5 months and the results of frequent groundwater sampling and analysis indicate an important decline in total petroleum hydrocarbons (TPH) and benzene–toluene–ethylbenzene–xylene (BTEX) concentrations (up to 99%). However, prior to any attempt to expand the application of air sparging within the facilities of the refinery, special attention should be given to the eccentricities of the site and the ability of the technology to confront more persistent contaminants, such as methyl tertiary-butyl ether (MTBE).
Effect of phase separation on anaerobic digestion of kitchen waste
Authors: Mohan S. , Bindhu B.K.
Published: April 2008

The anaerobic digestion of kitchen waste was studied in both batch and continuous modes. The effect of increasing loading rates on pollutant removal and biogas production was investigated for single-phase digestion and two-phase digestion systems. The anaerobic biodegradability of the kitchen waste obtained from the batch study was 83.5%. Single-stage digestion of kitchen waste was subjected to varying organic loading rates (OLR) ranging from 1.5 kg volatile solids (VS) m–3 d–1 to 5.5 kg VS m–3d–1, with a common hydraulic retention time (HRT) of 15 d. The optimum performance of the system was observed at an OLR of 4.5 kg VS m–3 d–1 in terms of pollutant removal efficiency and biogas production. The removal rates for chemical oxygen demand (COD) and VS at this optimal OLR were 81% and 79%, respectively. Maximum production of the methane was 0.288 m3/kg of VS added. Beyond the optimal OLR, the volatile fatty acids concentration increased and reached its maximum value (9.2 g/L) at the higher loading rate tested (5.5 kg VS m–3 d–1). Anaerobic digestion of the kitchen waste was carried out in a two-stage reactor with different loading rates of 4, 6, and 8 kg VS m–3 d–1. The retention time given to both hydrolysis and methanogenesis phases was 5 d, for a total HRT of 10 d. Best performances were observed in the third run with the OLR of 8 kg VS m–3 d–1. High removal efficiencies for COD and VS were found as 92% and 94%, respectively. A total of 0.22 m3 of methane was produced by 1 kg of VS added. Responses to the fluctuations in the loading rates were sudden and many times unfavourable in the single-stage system, while the fluctuations were suppressed or overcome at a faster rate in the two-stage reactor, without creating too many problems. Comparison of the overall performance showed that phase-separated digesters or the two-stage digesters may offer the best choice for high efficiency, concerning pollutant removal.
Inactivation of Bacillus subtilis on gypsum board using aerosolized chemical agents
Authors: Wagner Andrew , Green Christopher F. , Pedregon Veronica , Barth Edwin , Gibbs Shawn G. , Scarpino Pasquale V.
Published: April 2008

The ability of aerosolized disinfectant agents to reach exterior and interior spaces of walls and other difficult to access areas has potential as a remediation technique for contained biological contamination. Bacillus subtilis were evaluated against aerosolized solutions of distilled water (dH2O, control), 0.05% chlorine dioxide (ClO2), and 0.6% sodium hypochlorite (NaOCl). Bacillus subtilis endospores were inoculated onto commercially available gypsum board with paper facing. Aerosols generated from a collison nebulizer were directed into a sterile contact chamber housing the inoculated gypsum board for 4, 8, and 12 hour periods. Independent evaluations were conducted of the gypsum board where the organism B. subtilis were exposed to the aerosolized disinfectant. Treatment effects were evaluated through the collection of surface samples before and after exposures. The aerosolized 0.6% sodium hypochlorite solution was the only treatment successful in reducing the total concentration of B. subtilis. Treatment with sodium hypochlorite solution reduced B. subtilis organisms by 1.55-log after 4 h, 1.92-log after 8 h, and 2.50-log after 12 h of exposure, though the difference in log-reduction between exposure periods were not statistically significant.
Large chromosomal inversion correlated with spectinomycin resistance inLactococcus lactissubsp.lactisbv. diacetylactis S50
Authors: Kojic Milan , Jovcic Branko , Begovic Jelena , Fira Djordje , Topisirovic Ljubisa
Published: April 2008

A large chromosomal inversion that confers resistance to high concentrations of the antibiotic spectinomycin in Lactococcus lactis subsp. lactis bv. diacetylactis S50 was identified by pulsed field gel electrophoresis. The same type of inversion was identified in 4 independent experiments and in 4 different derivatives of strain S50, indicating the same position and the same mechanism of recombination as a response to antibiotic selective pressure in all derivatives. An analysis of ribosomal operons in strain S50 and mutants revealed that ribosomal operons are not endpoints of the recombination. Spectinomycin-resistant mutants appeared in a population of S50 derivatives at a high frequency of 2 × 10−7. These spectinomycin-resistant mutants were not able to compete successfully with the wild-type strain during 25 generations (48 h) of co-culture in vitro, indicating that inversion had a significant fitness cost. Results demonstrate that as a mechanism of genome plasticity, inversion can be directly involved in one-step development of the adaptation to a high concentration of spectinomycin.
Transcriptional regulation of ACC deaminase gene expression inPseudomonas putidaUW4
Authors: Cheng Zhenyu , Duncker Bernard P. , McConkey Brendan J. , Glick Bernard R.
Published: April 2008

One of the major mechanisms that plant growth-promoting bacteria use to facilitate plant growth is through the lowering of plant ethylene levels by the bacterial enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase. Many of the bacterial ACC deaminase genes (acdS) that have been examined to date are under the transcriptional control of a leucine-responsive regulatory protein, Lrp, encoded by acdR and referred to here as AcdR. The work presented here is focused on how AcdR and the newly discovered AcdB protein from Pseudomonas putida UW4 are involved in the regulation of acdS expression. First, the results of gel retardation experiments showed that AcdR binds to the acdS regulatory region, and this binding activity in vitro is not affected by the addition of 2 mmol·L–1ACC but can be eliminated by addition of 20 μg·mL–1leucine. Second, a potential regulatory protein, AcdB, involved in the regulation of acdS expression, was identified through both yeast 2-hybrid screen and coimmunoprecipitation based on its ability to bind to AcdR; subsequently, its binding to the acdS regulatory region in the presence of ACC was shown by gel retardation experiments. The data are interpreted in terms of a model in which AcdR and AcdB co-regulate the expression of the acdS gene.
Hydroxamate siderophores produced by Streptomyces acidiscabies E13 bind nickel and promote growth in cowpea (Vigna unguiculata L.) under nickel stress
Authors: Dimkpa Christian , Svatoš Aleš , Merten Dirk , Büchel Georg , Kothe Erika
Published: April 2008

The siderophore-producing ability of nickel-resistant Streptomyces acidiscabies E13 and the role of the elicited siderophores in promoting plant growth under iron and nickel stress are described. Siderophore assays indicated that S. acidiscabies E13 can produce siderophores. Electrospray ionization mass spectrometry (ESI-MS) revealed that the bacterium simultaneously produces 3 different hydroxamate siderophores. ESI-MS showed that in addition to iron, all 3 siderophores can bind nickel. In vitro plant growth tests were conducted with cowpea ( Vigna unguiculata ) in the presence and absence of the elicited siderophores. Culture filtrates containing hydroxamate siderophores significantly increased cowpea height and biomass, irrespective of the iron status of the plants, under nickel stress. The presence of reduced iron was found to be high in siderophore-containing treatments in the presence of nickel. Measurements of iron and nickel contents of cowpea roots and shoots indicated that the siderophore-mediated plant growth promotion reported here involves the simultaneous inhibition of nickel uptake and solubilization and supply of iron to plants. We conclude that hydroxamate siderophores contained in culture filtrates of S. acidiscabies E13 promoted cowpea growth under nickel contamination by binding iron and nickel, thus playing a dual role of sourcing iron for plant use and protecting against nickel toxicity.
Diversity of predominant endophytic bacteria in European deciduous and coniferous trees
Authors: Izumi Hironari , Anderson Ian C. , Killham Ken , Moore Edward R.B.
Published: April 2008

The diversity of endophytic bacteria residing in root, stem, and leaf tissues was examined in coniferous and deciduous tree species, Scots pine ( Pinus sylvestris L.), silver birch ( Betula pendula Roth), and rowan ( Sorbus aucuparia L.). Using cultivation-dependent and -independent analyses, the bacterial communities were observed to be significantly different in the belowground (roots and rhizosphere) and aboveground (leaves and stems) samples of the respective host trees. No significant differences, with respect to the different tree species, were observed in the associated communities. Predominant cultivable endophytes isolated included bacteria closely related to Bacillus subtilis , Bacillus licheniformis , Paenibacillus spp., and Acinetobacter calcoaceticus . Comparisons of the most abundant cultivable bacteria in the rhizosphere and root samples suggested that root endophytic bacteria may be in residence through processes of selection or active colonization rather than by passive diffusion from the rhizosphere.
Diversity and dynamics of lactobacilli populations during ripening of RDO Camembert cheese
Authors: Henri-Dubernet Ségolène , Desmasures Nathalie , Guéguen Micheline
Published: April 2008

The diversity and dynamics of Lactobacillus populations in traditional raw milk Camembert cheese were monitored throughout the manufacturing process in 3 dairies. Culture-dependent analysis was carried out on isolates grown on acidified de Man – Rogosa – Sharpe agar and Lactobacillus anaerobic de Man Rogosa Sharpe agar supplemented with vancomycin and bromocresol green media. The isolates were identified by polymerase chain reaction – temperature gradient gel electrophoresis (PCR–TGGE) and (or) species-specific PCR and (or) sequencing, and Lactobacillus paracasei and Lactobacillus plantarum isolates were characterized by pulsed field gel electrophoresis (PFGE). Milk and cheese were subjected to culture-independent analysis by PCR–TGGE. Presumed lactobacilli were detected by plate counts throughout the ripening process. However, molecular analysis of total DNA and DNA of isolates failed to detect Lactobacillus spp. in certain cases. The dominant species in the 3 dairies was L. paracasei. PFGE analysis revealed 21 different profiles among 39 L. paracasei isolates. Lactobacillus plantarum was the second most isolated species, but it occurred nearly exclusively in one dairy. The other species isolated were Lactobacillus parabuchneri , Lactobacillus fermentum , Lactobacillus acidophilus , Lactobacillus helveticus , a Lactobacillus psittaci/delbrueckii subsp. bulgaricus/gallinarum/crispatus group, Lactobacillus rhamnosus , Lactobacillus delbrueckii subsp. bulgaricus, L. delbrueckii subsp. lactis, Lactobacillus brevis , Lactobacillus kefiri , and Lactobacillus perolens. Lactobacilli diversity at the strain level was high. Dynamics varied among dairies, and each cheese exhibited a specific picture of species and strains.
HEMODYNAMIC INFORMATION AND ANALYSIS OF CARDIAC PUMPING
Authors: HUNG T. K. , BALASUBRAMANIAN S. R. , SIMON M. A. , SUFFOLETTO M. S. , BOROVETZ H. S. , GORCSAN J.
Published: April 2008

This study extracted hemodynamic information from echocardiogram to complement the left ventricle ejection fraction and the stroke volume for cardiac evaluation and diagnosis. The dynamic characteristics of irregular wall motions can be analyzed by kinetic energy fluxes transferred from the left ventricle to the blood flow. A set of cardiac indices is developed for quantification and classification of echocardiogram for clinical application. The pumping characteristics can be further quantified through the work done by pressure and viscous stresses of the ventricle.
SPACE-TIME DEFORMATIONS AS EXTENDED CONFORMAL TRANSFORMATIONS
Authors: CAPOZZIELLO S. , STORNAIOLO C.
Published: April 2008

A definition of space-time metric deformations on an n-dimensional manifold is given. We show that such deformations can be regarded as extended conformal transformations. In particular, their features can be related to the perturbation theory giving a natural picture by which gravitational waves are described by small deformations of the metric. As further result, deformations can be related to approximate Killing vectors (approximate symmetries) by which it is possible to parameterize the deformed region of a given manifold. The perspectives and some possible physical applications of such an approach are discussed.
QUANTUM MECHANICS AS A SPONTANEOUSLY BROKEN GAUGE THEORY ON A U(1) GERBE
Authors: ISIDRO JOSÉ M.
Published: April 2008

Any quantum-mechanical system possesses a U(1) gerbe naturally defined on configuration space. Acting on Feynman's kernel exp(iS/ħ), this U(1) symmetry allows one to arbitrarily pick the origin for the classical action S, on a point-by-point basis on configuration space. This is equivalent to the statement that quantum mechanics is a U(1) gauge theory. Unlike Yang–Mills theories, however, the geometry of this gauge symmetry is not given by a fibre bundle, but rather by a gerbe. Since this gauge symmetry is spontaneously broken, an analogue of the Higgs mechanism must be present. We prove that a Heisenberg-like noncommutativity for the space coordinates is responsible for the breaking. This allows to interpret the noncommutativity of space coordinates as a Higgs mechanism on the quantum-mechanical U(1) gerbe.
GENDER-ROLE ORIENTATION AS A DETERMINANT OF ENTREPRENEURIAL SELF-EFFICACY
Authors: MUELLER STEPHEN L. , DATO-ON MARY CONWAY
Published: April 2008

Entrepreneurial self-efficacy (ESE) is often included in entrepreneurial intentions models to explain why some individuals are more likely than others to become entrepreneurs. An unsettled question among researchers is whether ESE differs between men and women. While early studies seem to suggest that men have higher ESE than women, more recent studies are inconclusive. Lacking empirical support for gender differences in ESE compels researchers to look for other factors to explain variation in entrepreneurial self-efficacy.

The present study confirms two recent studies by finding no significant difference in ESE between men and women in a representative sample of MBA students. This finding leads to an investigation of gender-role orientation as a possible determinant of differences in entrepreneurial self-efficacy. Results indicate that the relationship between gender-role orientation and entrepreneurial self-efficacy is complex and multifaceted. Early in the venture creation process, the searching and planning tasks demand creativity and innovation where a strong mix of masculine and feminine traits (androgyny) improves performance. Later in the venture creation process, an individual (male or female) with a strong masculine orientation seems better suited for undertaking entrepreneurial tasks associated with persuading and leading others.
OPPORTUNITY RECOGNITION DIFFERENCES BETWEEN BLACK AND WHITE NASCENT ENTREPRENEURS: A TEST OF BHAVE'S MODEL
Authors: SINGH ROBERT P. , KNOX EDWIN L. , CRUMP MICAH E. S.
Published: April 2008

Examining the opportunity recognition processes of black and white entrepreneurs may help improve the lagging rate of black entrepreneurship. Based on the framework provided by Bhave's (1994) model of new venture creation, and using data collected through the Panel Study of Entrepreneurial Dynamics, we found significant differences between the percentage of black and white nascent entrepreneurs who recognized externally-stimulated versus internally-stimulated opportunities and their projected firm revenues. As predicted, black nascent entrepreneurs were more likely to pursue externally-stimulated opportunities with significantly lower expected revenues than their white counterparts. Academic and practical implications are discussed and future research directions are offered.
THE EFFECT OF STRATEGIC ORIENTATION AND GENDER ON SURVIVAL: A STUDY OF POTENTIAL MASS MERCHANDISING SUPPLIERS
Authors: KNOTTS TAMI L. , JONES STEPHEN C. , BROWN KAREN L.
Published: April 2008

While a market orientation is associated with superior performance (Narver and Slater, 1990; Kara et al., 2005), it may not be the only approach for small manufacturers (Noble et al., 2002). Our study examines whether two other orientations — production and marketing — influence the survival rate for small manufacturers wanting to supply the mass merchandising marketplace. We also investigate the impact of gender-related preferences on the continued existence of these firms.

The sample for this study consisted of 1,690 small, independently-owned manufacturers who participated in an evaluation program in order to become a supplier for a major mass merchandiser. Results showed that surviving firm owners placed more emphasis on production than marketing activities, while non-surviving firm owners did the opposite. When gender was considered, male-owners showed similar preferences as the general sample, but the reverse was true for female entrepreneurs. We conclude that an exclusive focus on a market orientation may be counterproductive to a firm's long-term success. For small manufacturers in the mass merchandising industry, both a production and marketing orientation are needed to survive.
Citizenship and Immigration: Multiculturalism, Assimilation, and Challenges to the Nation-State
Authors: Bloemraad Irene , Korteweg Anna , Yurdakul Gökçe
Published: April 2008

Citizenship encompasses legal status, rights, participation, and belonging. Traditionally anchored in a particular geographic and political community, citizenship evokes notions of national identity, sovereignty, and state control, but these relationships are challenged by the scope and diversity of international migration. This review considers normative and empirical debates over citizenship and bridges an informal divide between European and North American literatures. We focus on citizenship within nation-states by discussing ethnic versus civic citizenship, multiculturalism, and assimilation. Going beyond nation-state boundaries, we also look at transnational, postnational, and dual citizenships. Throughout, we identify methodological and theoretical challenges in this field, noting the need for a more dynamic and comprehensive understanding of the inter-relationships between the dimensions of citizenship and immigration.
Depletion of β-COP reveals a role for COP-I in compartmentalization of secretory compartments and in biosynthetic transport of caveolin-1
Authors: Styers Melanie L. , O'Connor Amber K. , Grabski Robert , Cormet-Boyaka Estelle , Sztul Elizabeth
Published: April 2008

We have utilized small interfering RNA (siRNA)-mediated depletion of the β-COP subunit of COP-I to explore COP-I function in organellar compartmentalization and protein traffic. Reduction in β-COP levels causes the colocalization of markers for the endoplasmic reticulum (ER)-Golgi intermediate compartment (ERGIC), Golgi, trans-Golgi network (TGN), and recycling endosomes in large, globular compartments. The lack of spatial differentiation of these compartments is not due to a general collapse of all cellular organelles since markers for the early endosomes and lysosomes do not redistribute to the common structures. Anterograde trafficking of the transmembrane cargo vesicular stomatitis virus membrane glycoprotein and of a subset of soluble cargoes is arrested within the common globular compartments. Similarly, recycling traffic of transferrin through the common compartment is perturbed. Furthermore, the trafficking of caveolin-1 (Cav1), a structural protein of caveolae, is arrested within the globular structures. Importantly, Cav1 coprecipitates with the γ-subunit of COP-I, suggesting that Cav1 is a COP-I cargo. Our findings suggest that COP-I is required for the compartmentalization of the ERGIC, Golgi, TGN, and recycling endosomes and that COP-I plays a novel role in the biosynthetic transport of Cav1.
Distinct pathways of ERK activation by the muscarinic agonists pilocarpine and carbachol in a human salivary cell line
Authors: Lin Alan L. , Zhu Bing , Zhang WanKe , Dang Howard , Zhang Bin-Xian , Katz Michael S. , Yeh Chih-Ko
Published: April 2008

Cholinergic-muscarinic receptor agonists are used to alleviate mouth dryness, although the cellular signals mediating the actions of these agents on salivary glands have not been identified. We examined the activation of ERK1/2 by two muscarinic agonists, pilocarpine and carbachol, in a human salivary cell line (HSY). Immunoblot analysis revealed that both agonists induced transient activation of ERK1/2. Whereas pilocarpine induced phosphorylation of the epidermal growth factor (EGF) receptor, carbachol did not. Moreover, ERK activation by pilocarpine, but not carbachol, was abolished by the EGF receptor inhibitor AG-1478. Downregulation of PKC by prolonged treatment of cells with the phorbol ester PMA diminished carbachol-induced ERK phosphorylation but had no effect on pilocarpine responsiveness. Depletion of intracellular Ca2+ ([Ca2+]i) by EGTA did not affect ERK activation by either agent. In contrast to carbachol, pilocarpine did not elicit [Ca2+]i mobilization in HSY cells. Treatment of cells with the muscarinic receptor subtype 3 (M3) antagonist N-(3-chloropropyl)-4-piperidnyl diphenylacetate decreased ERK responsiveness to both agents, whereas the subtype 1 (M1) antagonist pirenzepine reduced only the carbachol response. Stimulation of ERKs by pilocarpine was also decreased by M3, but not M1, receptor small interfering RNA. The Src inhibitor PP2 blocked pilocarpine-induced ERK activation and EGF receptor phosphorylation, without affecting ERK activation by carbachol. Our results demonstrate that the actions of pilocarpine and carbachol in salivary cells are mediated through two distinct signaling mechanisms—pilocarpine acting via M3 receptors and Src-dependent transactivation of EGF receptors, and carbachol via M1/M3 receptors and PKC—converging on the ERK pathway.
NO-induced regulation of human trabecular meshwork cell volume and aqueous humor outflow facility involve the BKCa ion channel
Authors: Dismuke William M. , Mbadugha Chigozirim C. , Ellis Dorette Z.
Published: April 2008

Nitric oxide (NO) donors decrease intraocular pressure (IOP) by increasing aqueous outflow facility in the trabecular meshwork (TM) and/or Schlemm's canal. However, the cellular mechanisms are unknown. Cellular mechanisms known to regulate outflow facility include changes in cell volume and cellular contractility. In this study, we investigated the effects of NO donors on outflow facility and NO-induced effects on TM cell volume. We tested the involvement of soluble guanylate cyclase (sGC), cGMP, PKG, and the large-conductance Ca2+-activated K+ (BKCa) channel using inhibitors and activators. Cell volume was measured using calcein AM fluorescent dye, detected by confocal microscopy, and quantified using NIH ImageJ software. An anterior segment organ perfusion system measured outflow facility. NO increased outflow facility in porcine eye anterior segments (0.4884–1.3956 μl·min−1·mmHg−1) over baseline (0.2373–0.5220 μl·min−1·mmHg−1) within 10 min of drug application. These NO-induced increases in outflow facility were inhibited by the the BKCa channel inhibitor IBTX. Exposure of TM cells to NO resulted in a 10% decrease in cell volume, and these decreases were abolished by the sGC inhibitor 1 H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one and IBTX, suggesting the involvement of sGC and K+ eflux, respectively. NO-induced decreases in cell volume were mimicked by 8-Br-cGMP and abolished by the PKG inhibitor (RP)-8-Br-PET-cGMP-S, suggesting the involvement cGMP and PKG. Additionally, the time course for NO-induced decreases in TM cell volume correlated with NO-induced increases in outflow facility, suggesting that the NO-induced alterations in cell volume may influence outflow facility.
A Kv channel with an altered activation gate sequence displays both “fast” and “slow” activation kinetics
Authors: Labro Alain J. , Grottesi Alessandro , Sansom Mark S. P. , Raes Adam L. , Snyders Dirk J.
Published: April 2008

The Kv1–4 families of K+ channels contain a tandem proline motif (P XP) in the S6 helix that is crucial for channel gating. In human Kv1.5, replacing the first proline by an alanine resulted in a nonfunctional channel. This mutant was rescued by introducing another proline at a nearby position, changing the sequence into AVPP. This resulted in a channel that activated quickly (ms range) upon the first depolarization. However, thereafter, the channel became trapped in another gating mode that was characterized by slow activation kinetics (s range) with a shallow voltage dependence. The switch in gating mode was observed even with very short depolarization steps, but recovery to the initial “fast” mode was extremely slow. Computational modeling suggested that switching occurred during channel deactivation. To test the effect of the altered P XP sequence on the mobility of the S6 helix, we used molecular dynamics simulations of the isolated S6 domain of wild type (WT) and mutants starting from either a closed or open conformation. The WT S6 helix displayed movements around the P XP region with simulations starting from either state. However, the S6 with a AVPP sequence displayed flexibility only when started from the closed conformation and was rigid when started from the open state. These results indicate that the region around the P XP motif may serve as a “hinge” and that changing the sequence to AVPP results in channels that deactivate to a state with an alternate configuration that renders them “reluctant” to open subsequently.
CaM kinase IIδ2-dependent regulation of vascular smooth muscle cell polarization and migration
Authors: Mercure Melissa Z. , Ginnan Roman , Singer Harold A.
Published: April 2008

Previous studies indicate involvement of the multifunctional Ca2+/calmodulin-dependent protein kinase II (CaMKII) in vascular smooth muscle (VSM) cell migration. In the present study, molecular loss-of-function studies were used specifically to assess the role of the predominant CaMKIIδ2 isoform on VSM cell migration using a scratch wound healing assay. Targeted CaMKIIδ2 knockdown using siRNA or inhibition of activity by overexpressing a kinase-negative mutant resulted in attenuation of VSM cell migration. Temporal and spatial assessments of kinase autophosphorylation indicated rapid and transient activation in response to wounding, in addition to a sustained activation in the leading edge of migrating and spreading cells. Furthermore, siRNA-mediated suppression of CaMKIIδ2 resulted in the inhibition of wound-induced Rac activation and Golgi reorganization, and disruption of leading edge morphology, indicating an important function for CaMKIIδ2 in regulating VSM cell polarization. Numerous previous reports link activation of CaMKII to ERK1/2 signaling in VSM. Wound-induced ERK1/2 activation was also found to be dependent on CaMKII; however, ERK activity did not account for effects of CaMKII in regulating Golgi polarization, indicating alternative mechanisms by which CaMKII affects the complex events involved in cell migration. Wounding a VSM cell monolayer results in CaMKIIδ2 activation, which positively regulates VSM cell polarization and downstream signaling, including Rac and ERK1/2 activation, leading to cell migration.
PI3K/Akt activation is critical for early hepatic regeneration after partial hepatectomy
Authors: Jackson Lindsey N. , Larson Shawn D. , Silva Scott R. , Rychahou Piotr G. , Chen L. Andy , Qiu Suimin , Rajaraman Srinivasan , Evers B. Mark
Published: April 2008

Hepatic resection is associated with rapid proliferation and regeneration of the remnant liver. Phosphatidylinositol 3-kinase (PI3K), composed of a p85α regulatory and a p110α catalytic subunit, participates in multiple cellular processes, including cell growth and survival; however, the role of PI3K in liver regeneration has not been clearly delineated. In this study, we used the potent PI3K inhibitor wortmannin and small interfering RNA (siRNA) targeting the p85α and p110α subunits to determine whether total or selective PI3K inhibition would abrogate the proliferative response of the liver after partial hepatectomy in mice. Hepatic resection is associated with an induction in PI3K activity; total PI3K blockade with wortmannin and selective inhibition of p85α or p110α with siRNA resulted in a significant decrease in hepatocyte proliferation, especially at the earliest time points. Fewer macrophages and Kupffer cells were present in the regenerating liver of mice treated with wortmannin or siRNA to p85α or p110α, as reflected by a paucity of F4/80-positive cells. Additionally, PI3K inhibition led to an aberrant architecture in the regenerating hepatocytes characterized by vacuolization, lipid deposition, and glycogen accumulation; these changes were not noted in the sham livers. Our data demonstrate that PI3K/Akt pathway activation plays a critical role in the early regenerative response of the liver after resection; inhibition of this pathway markedly abrogates the normal hepatic regenerative response, most likely by inhibiting macrophage infiltration and cytokine elaboration and thus hepatocyte priming for replication.