bluuebunny/crossref_metadata_2025 huggingface dataset:
Regulated Interaction of Tegument Proteins UL16 and UL11 from Herpes Simplex Virus
Authors: Chadha Pooja , Han Jun , Starkey Jason L. , Wills John W.
Published: August 2012

It is well known that proteins in the tegument (located between the viral capsid and envelope proteins) play critical roles in the assembly and budding of herpesviruses. Tegument proteins UL16 and UL11 of herpes simplex virus (HSV) are conserved among all the
Herpesviridae
. Although these proteins directly interact
in vitro
, UL16 was found to colocalize poorly with UL11 in cotransfected cells. To explain this discrepancy, we hypothesized that UL16 is initially made in an inactive form and is artificially transformed to the binding-competent state when cells are disrupted. Consistent with a regulated interaction, UL16 was able to fully colocalize with UL11 when a large C-terminal segment of UL16 was removed, creating mutant UL16(1-155). Moreover, membrane flotation assays revealed a massive movement of this mutant to the top of sucrose gradients in the presence of UL11, whereas both the full-length UL16 and the C-terminal fragment (residues 156 to 373) remained at the bottom. Further evidence for the presence of a C-terminal regulatory domain was provided by single-amino-acid substitutions at conserved cysteines (C269S, C271S, and C357S), which enabled the efficient interaction of full-length UL16 with UL11. Lastly, the binding site for UL11 was further mapped to residues 81 to 155, and to our surprise, the 5 Cys residues within UL16(1-155) are not required, even though the modification of free cysteines in UL16 with
N
-ethylmaleimide does in fact prevent binding. Collectively, these results reveal a regulatory function within the C-terminal region of UL16 that controls an N-terminal UL11-binding activity.
In Vivo
-Validated Essential Genes Identified in Acinetobacter baumannii by Using Human Ascites Overlap Poorly with Essential Genes Detected on Laboratory Media
Authors: Umland Timothy C. , Schultz L. Wayne , MacDonald Ulrike , Beanan Janet M. , Olson Ruth , Russo Thomas A.
Published: August 2012

A critical feature of a potential antimicrobial target is the characteristic of being essential for growth and survival during host infection. For bacteria, genome-wide essentiality screens are usually performed on rich laboratory media. This study addressed whether genes detected in that manner were optimal for the identification of antimicrobial targets since the
in vivo
milieu is fundamentally different. Mutant derivatives of a clinical isolate of
Acinetobacter baumannii
were screened for growth on human ascites, an
ex vivo
medium that reflects the infection environment. A subset of 34 mutants with unique gene disruptions that demonstrated little to no growth on ascites underwent evaluation in a rat subcutaneous abscess model, establishing 18 (53%) of these genes as
in vivo
essential. The putative gene products all had annotated biological functions, represented unrecognized or underexploited antimicrobial targets, and could be grouped into five functional categories: metabolic, two-component signaling systems, DNA/RNA synthesis and regulation, protein transport, and structural. These
A. baumannii in vivo
essential genes overlapped poorly with the sets of essential genes from other Gram-negative bacteria catalogued in the Database of Essential Genes (DEG), including those of
Acinetobacter baylyi
, a closely related species. However, this finding was not due to the absence of orthologs. None of the 18
in vivo
essential genes identified in this study, or their putative gene products, were targets of FDA-approved drugs or drugs in the developmental pipeline, indicating that a significant portion of the available target space within pathogenic Gram-negative bacteria is currently neglected.

IMPORTANCE
The human pathogen
Acinetobacter baumannii
is of increasing clinical importance, and a growing proportion of isolates are multiantimicrobial-resistant, pan-antimicrobial-resistant, or extremely resistant strains. This scenario is reflective of the general problem of a critical lack of antimicrobials effective against antimicrobial-resistant Gram-negative bacteria, such as
Pseudomonas aeruginosa
,
Klebsiella pneumoniae
,
Enterobacter
sp., and
Escherichia coli
. This study identified a set of
A. baumannii
genes that are essential for growth and survival during infection and demonstrated the importance of using clinically relevant media and
in vivo
validation while screening for essential genes for the purpose of developing new antimicrobials. Furthermore, it established that if a gene is absent from the Database of Essential Genes, it should not be excluded as a potential antimicrobial target. Lastly, a new set of high-value potential antimicrobial targets for pathogenic Gram-negative bacteria has been identified.
Evidence for Cascades of Perturbation and Adaptation in the Metabolic Genes of Higher Termite Gut Symbionts
Authors: Zhang Xinning , Leadbetter Jared R.
Published: August 2012

Termites and their gut microbes engage in fascinating dietary mutualisms. Less is known about how these complex symbioses have evolved after first emerging in an insect ancestor over 120 million years ago. Here we examined a bacterial gene, formate dehydrogenase (fdhF), that is key to the mutualism in 8 species of “higher” termite (members of theTermitidae, the youngest and most biomass-abundant and species-rich termite family). Patterns offdhFdiversity in the gut communities of higher termites contrasted strongly with patterns in less-derived (more-primitive) insect relatives (wood-feeding “lower” termites and roaches). We observed phylogenetic evidence for (i) the sweeping loss of several clades offdhFthat may reflect extinctions of symbiotic protozoa and, importantly, bacteria dependent on them in the last common ancestor of all higher termites and (ii) a radiation of genes from the (possibly) single allele that survived. Sweeping gene loss also resulted in (iii) the elimination of an entire clade of genes encoding selenium (Se)-independent enzymes from higher termite gut communities, perhaps reflecting behavioral or morphological innovations in higher termites that relaxed preexisting environmental limitations of Se, a dietary trace element. Curiously, several higher termite gut communities may have subsequently reencountered Se limitation, reinventing genes for Se-independent proteins via convergent evolution. Lastly, the presence of a novelfdhFlineage within litter-feeding and subterranean higher (but not other) termites may indicate recent gene “invasion” events. These results imply that cascades of perturbation and adaptation by distinct evolutionary mechanisms have impacted the evolution of complex microbial communities in a highly successful lineage of insects.

IMPORTANCESince patterns of relatedness between termite hosts are broadly mirrored by the relatedness of their symbiotic gut microbiota, coevolution between hosts and gut symbionts is rightly considered an important force that has shaped dietary mutualism since its inception over 120 million years ago. Apart from that concerning lateral gene or symbiont transfer between termite gut communities (for which no evidence yet exists), there has been little discussion of alternative mechanisms impacting the evolution of mutualism. Here we provide strong gene-based evidence for past environmental perturbations creating significant upheavals that continue to reverberate throughout the gut communities of species comprising a single termite lineage. We suggest that symbiont extinction events, sweeping gene losses, evolutionary radiations, relaxation and reemergence of key nutritional pressures, convergent evolution of similar traits, and recent gene invasions have all shaped gene composition in the symbiotic gut microbial communities of higher termites, currently the most dominant and successful termite family on Earth.
New alternate hosts for the rustsCronartium ribicolaandCronartium flaccidumin Finland
Authors: Kaitera Juha , Hiltunen Ritva
Published: August 2012

We explored the potential of the North European flora and some garden plants growing naturally outside Europe to support a reservoir of pine stem rusts. Live plants and detached leaves of 35 species in 16 families (Solanaceae, Verbenaceae, Grossulariaceae, Paeoniaceae, Balsaminaceae, Gentianaceae, Scrophulariaceae, Loasaceae, Tropaeolaceae, Acanthaceae, Myricaceae, Phrymaceae, Plantaginaceae, Orobanchaceae, Apocynaceae, and Fagaceae) were inoculated in the greenhouse and (or) laboratory with aeciospores of Cronartium ribicola J.C. Fisch. and Cronartium flaccidum (Alb. & Schwein) G. Winter in 2010. Cronartium flaccidum produced uredinia and (or) telia in 14 species in nine families, 11 of which represent new alternate hosts in Finland and nine also elsewhere (excluding Nemesia versicolor and Tropaeolum majus L.): Euphrasia stricta D. Wof. ex J.F. Lehm., N. versicolor E. Mey. ex Benth., Nemesia strumosa Benth., Verbena × hybrida Voss., Verbena officinalis L., Veronica longifolia L., Impatiens glandulifera Royle, T. majus, Loasa triphylla Juss., Asclepias incarnata L., and Bartsia alpina L. Cronartium ribicola formed fruitbodies in nine species and cultivars in five families, five of which are new alternate hosts for this species in Finland and also elsewhere: Mentzelia lindleyi Torr. & A. Gray, A. incarnata, B. alpina, L. triphylla, and T. majus. Both species of Cronartium infected four alternate hosts, each in its own family. The alternate host range of each Cronartium was wider than expected and wider than that previously described. In local natural forests, Euphrasia , Veronica , and Bartsia (in northern Finland) are potential hosts that are common and may be able to spread these rusts. The recently established ornamental I. glandulifera could provide the means to spread C. flaccidum to Scots pine ( Pinus sylvestris L.) in southern Finland, and species of Mentzelia may be important for the spread of C. ribicola.
MAIDENiso: a multiproxy biophysical model of tree-ring width and oxygen and carbon isotopes
Authors: Danis P.-A. , Hatté C. , Misson L. , Guiot J.
Published: August 2012

MAIDENiso is a new version of the process-based biogeochemical model MAIDEN of tree growth. Isotopic modules have been implemented to simulate stable oxygen and carbon isotopes in tree-ring cellulose (TRC). In addition to annual increment biomass, this new model version estimates δ18O and δ13C associated with the daily amount of carbon allocated to the stem. MAIDENiso only requires daily input data: minimal and maximal air temperatures, amount of precipitation, CO2 atmospheric concentration, and δ13C in CO2. MAIDENiso simulates tree-ring width, δ18O in precipitation (δ18OP), δ18O in soil water (δ18OSW), δ18O in xylem water (δ18OXW), δ18O in cellulose (δ18OTRC), and δ13C in cellulose (δ13CTRC). The model has been calibrated and validated with tree-ring series sampled in the Fontainebleau Forest (France) from 1953 to 2000. We first calibrated several parameters for the 1977–2000 period and then validated it for the independent 1953–1976 period. Over the complete interval (1953–2000), we obtained correlations between observations and simulations above 0.5 for both isotopic series and above 0.65 for tree growth series. An important feature of the model is its ability to simulate not only extreme values of tree growth, such as the effect of 1976 drought, but also its persistence over several years.
Long-term trends in tree mortality rates in the Alberta foothills are driven by stand development
Authors: Thorpe H.C. , Daniels L.D.
Published: August 2012

Tree mortality is a critical driver of stand dynamics, influencing forest structure, composition, and capacity for ecosystem service provision. In recent years, tree mortality has been gaining attention as dramatic occurrences of forest die-off have been linked to climate change. Using permanent sample plot data, we examined tree mortality rates in mature forests in west-central Alberta from 1956 to 2007. We quantified mortality risk at an individual-tree level as a function of size, local competition, and calendar year, a proxy for increasing temperature, and used maximum likelihood methods to estimate species-specific model parameters. Tree size and local competition were both important predictors of mortality risk. However, once these factors were included in our model, no additional variation could be attributed to calendar year, indicating that the trend of increasing tree mortality over time found in our raw data is primarily a result of stand development processes. This finding is supported by the changes in forest structure and composition that we documented over the study period. Stands generally increased in basal area and stem density, and lodgepole pine ( Pinus contorta var. latifolia Engelm. ex S. Watson) declined in abundance relative to the more shade-tolerant black spruce ( Picea mariana (Mill.) B.S.P.) and white spruce ( Picea glauca (Moench) Voss). Our results indicate that warming-related changes did not affect background tree mortality rates in mature forests in the Alberta foothills over the study period. These results also provide critical information for future studies of forest dynamics in the region.
Differences in crown characteristics between black (Picea mariana) and white spruce (Picea glauca)
Authors: Power Hugues , LeMay Valerie , Berninger Frank , Sattler Derek , Kneeshaw Daniel
Published: August 2012

Black spruce ( Picea mariana (Mill.) Britton, Sterns & Poggenb.) and white spruce ( Picea glauca (Moench) Voss) are phylogenetically proximal species that differ in productivity. Crown characteristics of these two species have not been extensively studied, in spite of the importance of these two species to the Canadian boreal forest and the importance of tree crowns for understanding and modelling tree growth. In this paper, we characterize and compare the crown lengths, crown profiles (i.e., radii), shapes, and surface areas of these two species using 65 white spruce and 57 black spruce trees destructively sampled in the provinces of Alberta, Ontario, and Quebec, Canada. Crown length was measured on every sample tree, while crown profile was obtained by reconstructing crowns from branch measurements. Our results showed that crown lengths did not differ between these two species given the same tree size and growth conditions. However, these two species establish under different growth conditions resulting in crown length differences. Further, differences in crown radii and profiles were found even under the same growth conditions. White spruce trees had wider crown radii and profiles changed from a parabola to a cone shape under increased density. As a result, differences in crown surface areas were found.
Long-term effects of thinning on growth and yield of an upland black spruce stand
Authors: Soucy Michel , Lussier Jean-Martin , Lavoie Luc
Published: August 2012

Knowledge of the long-term effects of silviculture treatments is crucial to forest management. The long-term effects of thinning, a common and widely used silviculture treatment, is little documented for upland black spruce ( Picea mariana (Mill.) Britton, Sterns & Poggenb.) stands. We revisited a partial cutting experiment installed in 1961 in a 65-year-old unmanaged upland black spruce stand. The aim was to document the long-term effects of thinning on tree and stand growth and to complete previously published results of the first 15 years of response to thinning by determining its influence in terms of merchantable volume. Free thinning was applied following three intensities: 0%, 25%, and 50% of total basal area removal. The retrospective analysis of growth rings showed that the response over the first 15 years was less significant when determined in net merchantable volume instead of net total volume. Heavily thinned plots, nonetheless, showed a net stand merchantable volume increment 33% greater than that of the unthinned plots. In the longer term, a spruce budworm ( Choristoneura fumiferana Clemens) outbreak affected the site; nevertheless, the heavily thinned plots maintained a superior tree growth rate and did not show senescence mortality like the other plots, allowing stand volume to catch up to that of the unthinned plots after 33 years. Results suggested that thinning upland black spruce stands may be useful in mitigating reductions in volume production associated with growing stands to longer rotations as called for by certain ecosystem-based management approaches.
Estimating consumption and remaining carbon in burned slash piles
Authors: Finkral Alex J. , Evans Alexander M. , Sorensen Christopher D. , Affleck David L.R.
Published: August 2012

Fuel reduction treatments to reduce fire risk have become commonplace in the fire adapted forests of western North America. These treatments generate significant woody debris, or slash, and burning this material in piles is a common and inexpensive approach to reducing fuel loads. Although slash pile burning is a common practice, there is little information on consumption or even a common methodology for estimating consumption. As considerations of carbon storage and emissions from forests increase, better means of quantifying burn piles are necessary. This study uses two methods, sector sampling and a form of line intersect sampling, for estimating both the percent consumption and conversion to charcoal in slash piles of ponderosa pine ( Pinus ponderosa Douglas ex P. Lawson & C. Lawson) in northern Arizona, USA. On average, burning released between 92% and 94% of the carbon in each slash pile to the atmosphere and converted between 0.05 and 0.34 Mg C·ha–1 to charcoal across the treatment area. These results demonstrate that burning slash piles converts significant quantities of carbon stored in wood to atmospheric carbon and charcoal, both of which should be considered as forest carbon accounting is further refined. Sector sampling and line intersect strategies produced similar estimates of consumption; however, the line intersect protocol was more easily and rapidly implemented.
Plantation forest leases: experiences of New Zealand Māori
Authors: Rotarangi Stephanie
Published: August 2012

Numerous scholars agree that to integrate stakeholder demands into forest management is the central challenge facing forestry science. A necessary step is to translate public views and expectations into forest management techniques. This study uses document analysis and in-depth interviews to understand the values and expectations of New Zealand’s indigenous people (Māori) who have exotic species forests planted on their ancestral land. The two case studies involve long-term forest lease arrangements where Māori families are the collective owners of the land but the forest is managed by third parties. The results suggest that the landowners’ overall view of forestry is more critically influenced by political frameworks than by forest management techniques. The structures of governance and tenure and the legislation affecting the land are viewed as complicated and constraining. However, after decades of experience, Māori have successfully incorporated plantation forests into their sense of people and place. Despite difficulties and disappointments, the land use of forestry and forest regimes are, overall, viewed favourably by the landowners, consistent with environmental considerations and their culture and values.
Application of shadow fraction models for estimating attributes of northern boreal forests
Authors: Luther Joan E. , Fournier Richard A. , Houle Mélanie , Leboeuf Antoine , Piercey Douglas E.
Published: August 2012

A shadow fraction method was developed previously for mapping forest attributes of northern black spruce ( Picea mariana (Mill.) Britton, Sterns & Poggenb.) forests. This paper evaluates application of the method for (i) balsam fir stands ( Abies balsamea (L.) Mill.), (ii) stands with higher volume and biomass than those of previous studies, and (iii) stands with a higher composition of deciduous trees and steeper slopes. Models developed for new test sites in (i) central Labrador and (ii) western Newfoundland were not statistically different from previous models for biomass, volume, and basal area. Relative root mean square errors (RMSEr) for central Labrador were slightly lower than those found in other test sites (RMSEr: 24%–29%) but higher for western Newfoundland (RMSEr = 37%–43%), attributed to the higher upper limit of measured attributes and increased presence of deciduous trees. Results suggest that reasonable estimates can be generated for conifer forests of northeastern Canada; however, an alternative solution is needed where mixed and deciduous stands are prevalent. Measurement of ground plots over a wider range of species composition and forest structure is recommended for broader application to northern boreal forests and to further assess the potential role of the shadow fraction method in national-scale inventory programs.
Reconstructing the competitive dynamics of mixed-oak neighborhoods
Authors: Zenner Eric K. , Heggenstaller Daniel J. , Brose Patrick H. , Peck JeriLynn E. , Steiner Kim C.
Published: August 2012

The disparity between the potential for latent oak dominance within a stand and their region-wide decline in importance value raises questions about the competitiveness of oaks in early stand dynamics. We reconstructed tree height growth dynamics in mixed-species neighborhoods to determine if currently dominant oaks were ever shorter than their competitors and at what age currently subordinate oaks fell behind. In 23–36 year old mixed-oak stands in two physiographic provinces of Pennsylvania, we identified dominant and subordinate northern red oaks ( Quercus rubra L.) and chestnut oaks ( Quercus prinus L.) competing with adjacent non-oaks (red maple ( Acer rubrum L.), sweet birch ( Betula lenta L.), and black cherry ( Prunus serotina Ehrh.)) of equal crown class. In each stand, we randomly selected 20 tree neighborhoods and collected stem cross sections every metre from the base to the tip of each tree. In the Allegheny Plateau province, dominant northern red oaks never averaged more than 2 m shorter than their competitors, while by age 20, subordinate oaks were commonly more than 2 m behind. Dominant chestnut oaks in the Ridge and Valley province were never more than 1 m shorter than their competitors; subordinate oaks, however, were generally always at least a metre behind. In both regions, growth dynamics of currently subordinate trees were indistinguishable from those of currently dominant trees during their first decade. Because oaks that were considerably behind at age 15 were likely to be subordinate by age 30, the window of opportunity for release to prevent oaks from becoming permanently overtopped and unable to recover may thus be relatively early (age 10–20).
MULTIMODAL COMPUTER-ASSISTED TRANSCRIPTION OF TEXT IMAGES AT CHARACTER-LEVEL INTERACTION
Authors: MARTÍN-ALBO DANIEL , ROMERO VERÓNICA , TOSELLI ALEJANDRO H. , VIDAL ENRIQUE
Published: August 2012

Currently, automatic handwriting recognition systems are ineffectual in unconstrained handwriting documents. Therefore, to obtain perfect transcriptions, heavy human intervention is required to validate and correct the results of such systems. Given that this post-editing process is inefficient and uncomfortable, a multimodal interactive approach has been proposed in previous works, which aims at obtaining correct transcriptions with the minimum human effort. In this approach, the user interacts with the system by means of an e-pen and/or more traditional methods such as keyboard or mouse. This user's feedback allows to improve system accuracy and multimodality increases system ergonomics and user acceptability. Until now, multimodal interaction has been considered only at whole-word level. In this work, multimodal interaction at character-level is studied, that may lead to more effective interactivity, since it is faster and easier to write only one character rather than a whole word. Here we study this kind of fine-grained multimodal interaction and present developments that allow taking advantage of interaction-derived context to significantly improve feedback decoding accuracy. Empirical tests on three cursive handwritten tasks suggest that, despite losing the deterministic accuracy of traditional peripherals, this approach can save significant amounts of user effort with respect to fully manual transcription as well as to noninteractive post-editing correction.
ON SUMMABLE, POSITIVE POISSON–MEHLER KERNELS BUILT OF AL-SALAM–CHIHARA AND RELATED POLYNOMIALS
Authors: SZABŁOWSKI PAWEŁ J.
Published: August 2012

Using special technique of expanding ratio of densities in an infinite series of polynomials orthogonal with respect to one of the densities, we obtain simple, closed forms of certain kernels built of the so-called Al-Salam–Chihara (ASC) polynomials. We consider also kernels built of some other families of polynomials such as the so-called big continuous q-Hermite polynomials that are related to the ASC polynomials. The constructed kernels are symmetric and asymmetric. Being the ratios of the densities they are automatically positive. We expand also reciprocals of some of the kernels, getting nice identities built of the ASC polynomials involving six variables like e.g., formula (3.6). These expansions lead to asymmetric, positive and summable kernels. The particular cases (referring to q = 1 and q = 0) lead to the kernels build of certain linear combinations of the ordinary Hermite and Chebyshev polynomials.
DILATION OF ARBITRARY SYMMETRIC QUANTUM DYNAMICAL SEMIGROUPS ON $B({\mathcal H})$
Authors: DAS BISWARUP
Published: August 2012

We prove the existence of Hudson–Parthasarathy dilation of a quantum dynamical semigroup on [Formula: see text], which is symmetric with respect to the canonical normal trace on it.
WICK CALCULUS FOR THE SQUARE OF A GAUSSIAN RANDOM VARIABLE WITH APPLICATION TO YOUNG AND HYPERCONTRACTIVE INEQUALITIES
Authors: LANCONELLI ALBERTO , SPORTELLI LUIGI
Published: August 2012

We investigate a probabilistic interpretation of the Wick product associated to the chi-square distribution in the spirit of the results obtained in Ref. 7 for the Gaussian measure. Our main theorem points out a profound difference from the previously studied Gaussian7 and Poissonian12 cases. As an application, we obtain a Young-type inequality for the Wick product associated to the chi-square distribution which contains as a particular case a known Nelson-type hypercontractivity theorem.
DERIVATIVE FORMULA AND APPLICATIONS FOR HYPERDISSIPATIVE STOCHASTIC NAVIER–STOKES/BURGERS EQUATIONS
Authors: WANG FENG-YU , XU LIHU
Published: August 2012

By using coupling method, a Bismut type derivative formula is established for the Markov semigroup associated to a class of hyperdissipative stochastic Navier–Stokes/Burgers equations. As applications, gradient estimates, dimension-free Harnack inequality, strong Feller property, heat kernel estimates and some properties of the invariant probability measure are derived.
TWISTED TOPOLOGICAL STRUCTURES RELATED TO M-BRANES II: TWISTED Wu ANDWucSTRUCTURES
Authors: SATI HISHAM
Published: August 2012

Studying the topological aspects of M-branes in M-theory leads to various structures related to Wu classes. First we interpret Wu classes themselves as twisted classes and then define twisted notions of Wu structures. These generalize many known structures, including Pin-structures, twisted Spin structures in the sense of Distler–Freed–Moore, Wu-twisted differential cocycles appearing in the work of Belov–Moore, as well as ones introduced by the author, such as twisted Membrane and twisted Stringcstructures. In addition, we introduce Wucstructures, which generalize Pincstructures, as well as their twisted versions. We show how these structures generalize and encode the usual structures defined via Stiefel–Whitney classes.
INSTITUTIONAL ENVIRONMENT FOR ENTREPRENEURSHIP: EVIDENCE FROM THE DEVELOPMENTAL STATES OF SOUTH KOREA AND UNITED ARAB EMIRATES
Authors: GUPTA VISHAL K. , YAYLA ALI ALPER , SIKDAR ARIJIT , CHA MIN-SEOK
Published: August 2012

The purpose of this research is to examine country institutional profile for encouraging entrepreneurial activity in two developmental states: South Korea and United Arab Emirates. Data was collected from business students in the two countries to examine the favorability of their institutional environment for entrepreneurship. Confirmatory factor analysis indicated high reliability, construct validity and internal consistency for the Korean and Arabic language versions of the questionnaire instrument in the respective countries. Results revealed important cross-national differences between the two countries in the regulatory, cognitive and normative dimensions of the institutional environment. Implications, limitations and future research directions are discussed.
PERFORMANCE OF NEWLY-FORMED MICRO FIRMS: THE ROLE OF CAPITAL FINANCING IN MINORITY-OWNED ENTERPRISES
Authors: ORTIZ-WALTERS ROWENA , GIUS MARK
Published: August 2012

We sought to ascertain whether newly-formed micro firms owned by minority entrepreneurs would be as likely to be profitable or not when compared to non-minority business owners. Additionally, we placed special emphasis on the impact of equity and debt to determine if capital financing influences firm profitability the same or differently for minority as compared to non-minority owned micro firms. Using longitudinal data from the Kauffman Firm Survey, micro firms owned by Hispanic and Black entrepreneurs were less likely to be profitable than non-minority owned micro firms, whereas profitability differences were not found between the latter and Asian-owned micro firms. Moreover, Hispanic and Black-owned micro firms that made use of personal debt were more likely to be profitable than those using only equity to finance operations. Asian-owned micro firms that utilized business debt were more likely to earn a profit than those solely using equity. Alternatively, non-minority owners benefited in terms of profitability from the use of both personal and business debt. Implications of these findings for minority entrepreneurship are discussed.
INDIGENOUS ENTREPRENEURSHIP IN NORTHERN NSW, AUSTRALIA
Authors: SHOEBRIDGE AMANDA , BUULTJENS JEREMY , PETERSON LILA SINGH
Published: August 2012

A number of solutions have been suggested for overcoming the considerable and entrenched economic and social disadvantage indigenous Australians face, including the encouragement to gain employment in the mainstream economy and to become entrepreneurs. Governments of all persuasions have implemented policies to encourage indigenous entrepreneurship; however, most appear to have had little success. To support and promote indigenous entrepreneurship effectively, it is important to identify the factors that either promote or hinder entrepreneurial endeavors. This paper reports on a study that used a qualitative research approach guided by a social constructivist paradigm to examine the experiences of Indigenous entrepreneurs in Northern New South Wales, Australia. The study results indicated that participants were found to possess characteristics of confidence, strong self-determination and ambition, and a desire to achieve. The role and influence of spouses, extended family and other role models were important determinants of entrepreneurial success, as were access to financial capital and established business networks. Above average education levels, prior industry experience and the assistance of mentors were also found to positively influence success. Lacking access to financial capital was a major hindrance. Participants also found government assistance programs confusing, unwieldy and difficult to access. Other hindrances included the presence of racism and discrimination; and difficulties reconciling business needs with the requests and needs of family, culture and community.
BEYOND THE COMMERCIAL VERSUS SOCIAL ENTREPRENEURSHIP DICHOTOMY: A CASE STUDY OF INFORMAL ENTREPRENEURS
Authors: WILLIAMS COLIN C. , NADIN SARA
Published: August 2012

Despite a widespread recognition in the mainstream entrepreneurship literature that many legitimate entrepreneurs do not pursue purely profit-driven commercial goals, the small but burgeoning literature on entrepreneurship in the informal economy has assumed entrepreneurs operating wholly or partially on an off-the-books basis are commercial rather than social entrepreneurs. To evaluate critically this assumption, evidence is reported from a survey involving face-to-face interviews with 70 informal entrepreneurs located in deprived and affluent urban and rural English localities. The finding is that informal entrepreneurs range from those pursuing purely commercial ends through to purely social entrepreneurs pursuing solely social logics, with the majority situated somewhere in-between combining both commercial and social objectives. The outcome is a call to recognize that not all informal entrepreneurs are purely commercial entrepreneurs and that the commercial versus social entrepreneurship dichotomy will need to be transcended if the multifarious goals underpinning informal entrepreneurship are to be better understood.
ELECTRICALLY CONDUCTIVE NANOCOMPOSITES OF EPOXY/POLYANILINE NANOWIRES DOPED WITH FORMIC ACID: EFFECT OF LOADING ON THE CONDUCTION AND MECHANICAL PROPERTIES
Authors: ABD RAZAK SAIFUL IZWAN , RAHMAN WAN AIZAN WAN ABDUL , YAHYA MOHD YAZID
Published: August 2012

This paper reports the preparation and characterization of nanocomposites consisting of epoxy resin (EP) and conducting polyaniline nanowires doped with formic acid (PANI-FA). The percolation threshold of this nanocomposites was obtained at 8 wt.% of PANI-FA loading. On the other hand, 8 wt.% of PANI-FA resulted in reduction of tensile and flexural modulus up to 30% and 16%, respectively. The fracture morphological analysis revealed a distinct PANI-FA domain on the EP matrix after the percolation threshold has been reached. Using the scaling law of the percolation theory, it was found that the conductivity of the nanocomposites exhibited an exponential factor, (t) of 0.417.
HLA class I-mediated stress fiber formation requires ERK1/2 activation in the absence of an increase in intracellular Ca2+ in human aortic endothelial cells
Authors: Ziegler Mary E. , Jin Yi-Ping , Young Steven H. , Rozengurt Enrique , Reed Elaine F.
Published: August 2012

Following transplantation, HLA class I antibodies targeting donor endothelium stimulate cell proliferation and migration, which contribute to the development of transplant vasculopathy and chronic allograft rejection. Dynamic remodeling of the actin cytoskeleton regulates cell proliferation and migration in endothelial cells (ECs), but the mechanism(s) involved remain incompletely understood. We explored anti-HLA class I antibody-mediated alterations of the cytoskeleton in human aortic ECs (HAECs) and contrasted these findings to thrombin-induced cytoskeleton remodeling. Our results identify two different signaling pathways leading to myosin light chain (MLC) phosphorylation in HAECs. Stimulation of HAECs with thrombin at 1 U/ml induced a robust elevation of intracellular Ca2+ concentration, increased MLC phosphorylation, and promoted stress fiber formation via MLC kinase (MLCK) and Rho kinase (ROK) in an ERK-independent manner. In contrast, HAECs stimulated with HLA class I antibodies did not promote any detectable change in intracellular Ca2+ concentration but instead induced MLC phosphorylation and stress fiber assembly via MLCK and ROK in an ERK1/2-dependent manner. Stimulation of HAECs with low-dose thrombin (1 mU/ml) induced signaling cascades that were similar to stimulation with HLA class I antibodies. HLA class I antibodies also stimulated the translocation of mammalian target of rapamycin complex 2 (mTORC2) and ERK1/2 from the cytoplasm to the plasma membrane independently of stress fiber assembly. These findings identify novel roles for HLA class I signaling in ECs and provide new insights into the role of ERK1/2 and mTORC2 in cytoskeleton regulation, which may be important in promoting transplant vasculopathy, tumor angiogenesis, and atherosclerosis.
Trafficking of an endogenous potassium channel in adult ventricular myocytes
Authors: Wang Tiantian , Cheng Yvonne , Dou Ying , Goonesekara Charitha , David Jens-Peter , Steele David F. , Huang Chen , Fedida David
Published: August 2012

The roles of several small GTPases in the expression of an endogenous potassium current, Ito,f, in adult rat ventricular myocytes have been investigated. The results indicate that forward trafficking of newly synthesized Kv4.2, which underlies Ito,f in these cells, requires both Rab1 and Sar1 function. Expression of a Rab1 dominant negative (DN) reduced Ito,f current density by roughly one-half relative to control, mCherry-transfected myocytes. Similarly, expression of a Sar1DN nearly halved Ito,f current density. Rab11 is not essential to trafficking of Kv4.2, as expression of a Rab11DN had no effect on Ito,f over the time frames investigated here. In a process dependent on intact endoplasmic reticulum (ER)-to-Golgi transport, however, overexpression of wild-type Rab11 resulted in a doubling of Ito,f density; block of ER-to-Golgi traffic by Brefeldin A completely abrogated the effect. Also implicated in the trafficking of Kv4.2 are Rab5 and Rab4. Rab5DN expression increased endogenous Ito,f by two- to threefold, nonadditively with inhibition of dynamin-dependent endocytosis. And, in a phenomenon similar to that previously reported for myoblast-expressed Kv1.5, Rab4DN expression roughly doubled endogenous peak transient currents. Colocalization experiments confirmed the involvement of Rab4 in postinternalization trafficking of Kv4.2. There was little role evident for the lysosome in the degradation of internalized Kv4.2, as overexpression of neither wild-type nor DN isoforms of Rab7 had any effect on Ito,f. Instead, degradation may depend largely on the proteasome; the proteasome inhibitor MG132 significantly increased Ito,f density.
Coupling of epithelial Na+ and Cl− channels by direct and indirect activation by serine proteases
Authors: Gondzik Veronika , Weber Wolf Michael , Awayda Mouhamed S.
Published: August 2012

The mammalian collecting duct (CD) is continuously exposed to urinary proteases. The CD expresses an epithelial Na+ channel (ENaC) that is activated after cleavage by serine proteases. ENaC also exists at the plasma membrane in the uncleaved form, rendering activation by extracellular proteases an important mechanism for regulating Na+ transport. Many exogenous and a small number of endogenous extracellular serine proteases have been shown to activate the channel. Recently, kallikrein 1 (KLK1) was shown to increase γENaC cleavage in the native CD indicating a possible direct role of this endogenous protease in Na+ homeostasis. To explore this process, we examined the coordinated effect of this protease on Na+ and Cl− transport in a polarized renal epithelial cell line (Madin-Darby canine kidney). We also examined the role of native urinary proteases in this process. Short-circuit current ( Isc) was used to measure transport of these ions. The Isc exhibited an ENaC-dependent Na+ component that was amiloride blockable and a cystic fibrosis transmembrane conductance regulator (CFTR)-dependent Cl− component that was blocked by inhibitor 172. Apical application of trypsin, an exogenous S1 serine protease, activated IENaC but was without effects on ICFTR. Subtilisin an exogenous S8 protease that mimics endogenous furin-type proteases activated both currents. A similar activation was also observed with KLK1 and native rat urinary proteases. Activation with urinary proteases occurred within minutes and at protease concentrations similar to those in the CD indicating physiological significance of this process. ENaC activation was irreversible and mediated by enhanced cleavage of γENaC. The activation of CFTR was indirect and likely dependent on activation of an endogenous apical membrane protease receptor. Collectively, these data demonstrate coordinated stimulation of separate Na+ and Cl− transport pathways in renal epithelia by extracellular luminal proteases. They also indicate that baseline urinary proteolytic activity is sufficient to modify Na+ and Cl− transport in these epithelia.
Matrix metalloproteinase-2 stimulates collagen-I expression through phosphorylation of focal adhesion kinase in rat cardiac fibroblasts
Authors: Hori Yasutomo , Kashimoto Takashige , Yonezawa Tomohiro , Sano Naoya , Saitoh Ryuta , Igarashi Shinya , Chikazawa Seishiro , Kanai Kazutaka , Hoshi Fumio , Itoh Naoyuki , Higuchi Sei-Ichi
Published: August 2012

Collagen-I is thought to be the main component of the extracellular matrix in cardiac fibrosis, the accumulation of which occurs with excessive activation of matrix metalloproteinase-2 (MMP-2). MMP-2 degrades the extracellular matrix; however, the relative importance of MMP-2 to collagen-I synthesis in cardiac fibroblasts remains unclear. We investigated whether extracellular activation of MMP-2 regulates collagen-I synthesis and phosphorylation of focal adhesion kinase (FAK) in rat cardiac fibroblasts. Primary cultures of rat cardiac fibroblasts were incubated with purified active MMP-2 to determine whether extracellular MMP-2 affects collagen-I synthesis and FAK phosphorylation in cardiac fibroblasts. Exogenous MMP-2 significantly stimulated FAK (Tyr397) phosphorylation and induced collagen-I expression in a time-dependent manner. Simultaneous treatment with the FAK inhibitor PF573228 abolished exogenous MMP-2-enhanced FAK (Tyr397) phosphorylation and collagen-I expression. Cells were then stimulated with norepinephrine (NE) to investigate whether endogenous MMP-2 could also induce collagen-I expression through FAK (Tyr397) phosphorylation. NE-stimulated endogenous MMP-2 activation in conditioned medium was significantly attenuated by simultaneous treatment with the MMP inhibitor PD166793. Similarly, NE-induced FAK (Tyr397) phosphorylation and collagen-I expression were significantly inhibited by simultaneous treatment with PD166793 or PF573228. Furthermore, MMP-2 knockdown induced by small interfering RNA (siRNA) significantly abolished endogenous MMP-2 expression and activation. MMP-2 siRNA significantly abolished NE-induced FAK (Tyr397) phosphorylation and collagen-I expression. These findings suggest that the extracellular activation of MMP-2 accelerated collagen-I synthesis in rat cardiac fibroblasts and that FAK phosphorylation (Tyr397) plays a pivotal role in MMP-2-stimulated collagen-I synthesis.
Insulin reduces excitation in gastric-related neurons of the dorsal motor nucleus of the vagus
Authors: Blake Camille B. , Smith Bret N.
Published: August 2012

The dorsal motor nucleus of the vagus (DMV) in the caudal brain stem is composed mainly of preganglionic parasympathetic neurons that control the subdiaphragmatic viscera and thus participates in energy homeostasis regulation. Metabolic pathologies, including diabetes, can disrupt vagal circuitry and lead to gastric dysfunction. Insulin receptors (IRs) are expressed in the DMV, and insulin crosses the blood-brain barrier and is transported into the brain stem. Despite growing evidence that insulin action in the brain is critical for energy homeostasis, little is known about insulin's action in the DMV. We used whole cell patch-clamp recordings in brain stem slices to identify effects of insulin on membrane and synaptic input properties of DMV neurons, including a subset of gastric-related cells identified subsequent to injection of a retrograde label into the gastric wall. Insulin application significantly reduced the frequency of spontaneous and miniature excitatory, but not inhibitory postsynaptic currents, with no change in amplitude ( P < 0.05). Insulin also directly hyperpolarized the membrane potential (−4.2 ± 1.3 mV; P < 0.05) and reduced action potential firing ( P < 0.05). Insulin effects were eliminated in the presence of a ATP-dependent K+ (KATP) channel antagonist tolbutamide (200 μM), or the phosphatidylinositol 3-kinase (PI3K) inhibitor wortmannin (100 nM), suggesting that insulin inhibition of excitatory input to gastric-related DMV neurons was mediated by KATP channels and depended on PI3K activity. Insulin regulation of synaptic input in the DMV may influence autonomic visceral regulation and thus systemic glucose metabolism.
Noninvasive estimation of microvascular O2 provision during exercise on-transients in healthy young males
Authors: Murias Juan M. , Spencer Matthew D. , Pogliaghi Silvia , Paterson Donald H.
Published: August 2012

Two methods for estimating changes in microvascular O2 delivery during the on-transient of exercise were evaluated. They were tested to assess the role of the adjustment of the estimated microvascular O2 delivery in the speeding of V̇o2 kinetics during a Mod1-Hvy-Mod2 protocol (Mod, moderate-intensity exercise; Hvy, heavy-intensity “priming” exercise), in which Mod2 is preceded by a bout of Hvy. Mod pulmonary V̇o2 (V̇o2p) and deoxy-hemoglobin [HHb] data were collected in 12 males (23 ± 3 yr); response profiles were fit with a monoexponential. Signals were also 1) scaled to a relative % of the response (0–100%) to calculate the [HHb]/V̇o2 ratio for each individual and 2) rearranged in the Fick equation for estimation of capillary blood flow (Qcap). A transient [HHb]/V̇o2 “overshoot” observed in Mod1 (1.06 ± 0.05; P < 0.05) was absent during Mod2 (1.01 ± 0.06; P > 0.05); reductions in the [HHb]/V̇o2 ratio (Mod1 − Mod2) were related to reductions in phase II τV̇o2p ( r = 0.82; P < 0.05). For Qcap, a near-exponential response was observed in 8/12 subjects in Mod1 and only in 4/12 subjects in Mod2. The Qcap profile was shown to be highly dependent on the [HHb] baseline-to-amplitude ratio. Thus, accurate and physiologically consistent estimations of Qcap were not possible in most cases. This study confirmed that priming exercise results in an improved O2 delivery as shown by the decreased [HHb]/V̇o2 ratio that was related to the smaller τV̇o2 in Mod2. Additionally, this study suggested that Qcap analysis may not be valid and should be interpreted with caution when assessing microvascular delivery of O2.
Neural encoding of sound source location in the presence of a concurrent, spatially separated source
Authors: Day Mitchell L. , Koka Kanthaiah , Delgutte Bertrand
Published: August 2012

In the presence of multiple, spatially separated sound sources, the binaural cues used for sound localization in the horizontal plane become distorted from the cues from each sound in isolation, yet localization in everyday multisource acoustic environments remains robust. We examined changes in the azimuth tuning functions of inferior colliculus (IC) neurons in unanesthetized rabbits to a target broadband noise when a concurrent broadband noise interferer was presented at different locations in virtual acoustic space. The presence of an interferer generally degraded sensitivity to target azimuth and distorted the shape of the tuning function, yet most neurons remained significantly sensitive to target azimuth and maintained tuning function shapes somewhat similar to those for the target alone. Using binaural cue manipulations in virtual acoustic space, we found that single-source tuning functions of neurons with high best frequencies (BFs) were primarily determined by interaural level differences (ILDs) or monaural level, with a small influence of interaural time differences (ITDs) in some neurons. However, with a centrally located interferer, the tuning functions of most high-BF neurons were strongly influenced by ITDs as well as ILDs. Model-based analysis showed that the shapes of these tuning functions were in part produced by decorrelation of the left and right cochlea-induced envelopes that occurs with source separation. The strong influence of ITD on the tuning functions of high-BF neurons poses a challenge to the “duplex theory” of sound localization and suggests that ITD may be important for localizing high-frequency sounds in multisource environments.