bluuebunny/crossref_metadata_2025 huggingface dataset:
Extracellular nucleotides affect pericyte‐mediated regulation of rat in situ vasa recta diameter
Authors: Crawford C. , Kennedy‐Lydon T. M. , Callaghan H. , Sprott C. , Simmons R. L. , Sawbridge L. , Syme H. M. , Unwin R. J. , Wildman S. S. P. , Peppiatt‐Wildman C. M.
Published: April 2011

Aim:  We hypothesized that extracellular nucleotides, established as being released from renal tubular epithelial cells, act at pericytes to regulate vasa recta capillary diameter.

Methods:  A rat live kidney slice model and video imaging techniques were used to investigate the effects of extracellular nucleotides on in situ (subsurface) vasa recta diameter at pericyte and non‐pericyte sites. In addition, RT‐qPCR was used to quantify P2 receptor mRNA expression in isolated vasa recta.

Results:  Extracellular ATP, UTP, benzylbenzyl ATP (BzATP) or 2‐methylthioATP (2meSATP) evoked a significantly greater vasoconstriction of subsurface vasa recta at pericytes than at non‐pericyte sites. The rank order of agonist potency was BzATP = 2meSATP > ATP = UTP. The vasoconstriction evoked at pericyte sites by ATP was significantly attenuated by the P2 receptor antagonists suramin, pyridoxal phosphate‐6‐azo(benzene‐2,4‐disulfonic acid) (PPADS) or Reactive Blue‐2 (RB‐2). UTP‐evoked vasoconstriction at pericytes was attenuated by suramin or RB‐2 but not PPADS. Interestingly, suramin or PPADS, when applied in the absence of a P2 receptor agonist, evoked a weak but significant vasoconstriction of vasa recta at pericyte sites, suggesting tonic vasodilation by nucleotides. Significant levels of P2X1, 3 and 7 and P2Y4 and 6 receptor mRNA were detected in vasa recta.

Conclusion:  Extracellular nucleotides act at pericytes to cause vasoconstriction of in situ vasa recta. Pharmacological characterization, supported by RT‐qPCR data, suggests that P2X1 and 7 and P2Y4 receptors mediate nucleotide‐evoked vasoconstriction of vasa recta by pericytes. We propose that nucleotides released from renal tubular epithelial cells, in close proximity to vasa recta capillaries, are key in regulating renal medullary blood flow.
Gas exchange in frogs and turtles: how ectothermic vertebrates contributed to solving the controversy of pulmonary oxygen secretion
Authors: Wang T.
Published: April 2011

The mechanisms governing pulmonary gas exchange were heavily debated at the start of the 20th century when Christian Bohr provided measurements of lung and blood gases as well as rational arguments in favour of oxygen being secreted actively from the lung gas to the blood within vertebrate lungs. The concept of active transport was studied by August Krogh in his doctoral dissertation on the partitioning of gas exchange in frogs. In later studies, where Marie and August Krogh provided conclusive evidence that pulmonary gas exchange occurs by diffusion and diffusion alone, the turtle lungs provided an important tool to investigate the role of perfusion in pulmonary gas exchange. Here, I review the early Bohr and Krogh studies on pulmonary and cutaneous gas exchange in frogs as well as the experimental studies on gas exchange and its possible autonomic regulation in turtles. The results are discussed within the context of recent studies on the cardiorespiratory physiology of frogs and turtles.
Myeloid‐Derived Suppressor Cells Limit the Inflammation by Promoting T Lymphocyte Apoptosis in the Spinal Cord of a Murine Model of Multiple Sclerosis
Authors: Moliné‐Velázquez Verónica , Cuervo Henar , Vila‐del Sol Virginia , Ortega María Cristina , Clemente Diego , de Castro Fernando
Published: April 2011

Multiple Sclerosis (MS) is a demyelinating/inflammatory disease of the central nervous system. Relapsing‐remitting MS is characterized by a relapsing phase with clinical symptoms and the production of inflammatory cell infiltrates, and a period of remission during which patients recover partially. Myeloid‐derived suppressor cells (MDSCs) are immature cells capable of suppressing the inflammatory response through Arginase‐I (Arg‐I) activity, among other mechanisms. Here, we have identified Arg‐I+‐MDSCs in the spinal cord during experimental autoimmune encephalomyelitis (EAE), cells that were largely restricted to the demyelinating plaque and that always exhibited the characteristic MDSC surface markers Arg‐I/CD11b/Gr‐1/M‐CSF1R. The presence and density of Arg‐I+‐cells, and the proportion of apoptotic but not proliferative T cells, were correlated with the EAE time course: peaked in parallel with the clinical score, decreased significantly during the remitting phase and completely disappeared during the chronic phase. Spinal cord‐isolated MDSCs of EAE animals augmented the cell death when co‐cultured with stimulated control splenic CD3 T cells. These data point to an important role for MDSCs in limiting inflammatory damage in MS, favoring the relative recovery in the remitting phase of the disease. Thus, the MDSC population should be considered as a potential therapeutic target to accelerate the recovery of MS patients.
Integrative Families and Systems Treatment: A Middle Path Toward Integrating Common and Specific Factors in Evidence‐Based Family Therapy
Authors: Fraser J. Scott , Solovey Andrew D. , Grove David , Lee Mo Yee , Greene Gilbert J.
Published: April 2011

A moderate common factors approach is proposed as a synthesis or middle path to integrate common and specific factors in evidence‐based approaches to high‐risk youth and families. The debate in family therapy between common and specific factors camps is reviewed and followed by suggestions from the literature for synthesis and creative flexibility in manual development. A preliminary integrative model termed Integrative Family and Systems Treatment is offered as one option in developing and testing a moderate common factors approach. Such a model might then be studied in eventual clinical trials with other well‐developed evidence‐based protocols to further address the common versus specific factor debate. Implications for further research and practice are offered.
The Mental Health Recovery Movement and Family Therapy, Part I: Consumer‐Led Reform of Services to Persons Diagnosed with Severe Mental Illness
Authors: Gehart Diane R.
Published: April 2011

In 2004, the U.S. Department of Health and Human Services issued a consensus statement on mental health recovery based on the New Freedom Commission’s recommendation that public mental health organizations adopt a “recovery” approach to severe and persistent mental illness, including services to those dually diagnosed with mental health and substance abuse issues. By formally adopting and promoting a recovery orientation to severe mental illness, the United States followed suit with other first‐world nations that have also adopted this approach based on two decades of research by the World Health Organization. This movement represents a significant paradigm shift in the treatment of severe mental health, a shift that is more closely aligned with the nonpathologizing and strength‐based traditions in marriage and family therapy. Furthermore, the recovery movement is the first consumer‐led movement to have a transformational effect on professional practice, thus a watershed moment for the field. Part I of this article introduces family therapists to the concept of mental health recovery, providing an overview of its history, key concepts, and practice implications. Part II of this article outlines a collaborative, appreciative approach for working in recovery‐oriented contexts.
“Seeking the Absentee”: A European Perspective on Evangelism in the Wake of a Feral God
Authors: Cruchley‐Jones Peter
Published: April 2011

Abstract
Europe's religious “demise” is well reported and often lamented in missionary circles. This article aims to offer a contrary perspective using the common approach of evangelism: “double listening”. The task is to listen to our culture and our text in conversation and to discover what the text is saying afresh to our needs and values. It is, however, largely expected that this double listening will yield itself to the means by which Christ can change and counter culture. But what if our double listening reveals the deafness of evangelism to the voice of Christ in our culture? This paper aims to explore the widespread religious experience in Europe of God's absence, and how it prompts us to re‐examine the stories of Jesus and the rhetoric we use to describe Europe's religious life. It contends that much evangelism in Europe is too inhospitable or unsophisticated to see this absence as anything other than something we should rush to fill with the latest model of our reliable 24/7 god. However, it might be leading us to acknowledge something about the life of faith that Jesus seems to offer in much of his teaching. Europe's resistance to organized religion is painful to experience, but it might be inviting us into a fresh conversion to what God is doing beyond our walls. If so, evangelism will have to learn a fresh humility as well as to provide the fresh energy to discover and partner God there.
Towards a better understanding of the legibility bias in performance assessments: The case of gender‐based inferences
Authors: Greifeneder Rainer , Zelt Sarah , Seele Tim , Bottenberg Konstantin , Alt Alexander
Published: April 2011

Background. Handwriting legibility systematically biases evaluations in that highly legible handwriting results in more positive evaluations than less legible handwriting. Because performance assessments in educational contexts are not only based on computerized or multiple choice tests but often include the evaluation of handwritten work samples, understanding the causes of this bias is critical.

Aims. This research was designed to replicate and extend the legibility bias in two tightly controlled experiments and to explore whether gender‐based inferences contribute to its occurrence.

Sample(s). A total of 132 students from a German university participated in one pre‐test and two independent experiments.

Method. Participants were asked to read and evaluate several handwritten essays varying in content quality. Each essay was presented to some participants in highly legible handwriting and to other participants in less legible handwriting. In addition, the assignment of legibility to participant group was reversed from essay to essay, resulting in a mixed‐factor design.

Results. The legibility bias was replicated in both experiments. Results suggest that gender‐based inferences do not account for its occurrence. Rather it appears that fluency from legibility exerts a biasing impact on evaluations of content and author abilities.

Conclusions. The legibility bias was shown to be genuine and strong. By refuting a series of alternative explanations, this research contributes to a better understanding of what underlies the legibility bias. The present research may inform those who grade on what to focus and thus help to better allocate cognitive resources when trying to reduce this important source of error.
The effect of guiding questions on students’ performance and attitude towards statistics
Authors: Budé Luc , van de Wiel M. W. J. , Imbos Tjaart , Berger Martijn P. F.
Published: April 2011

Background. In this study, the effect of guidance on students’ performance was investigated. This effect was hypothesized to be manifested through a reduction of cognitive load and enhancement of self‐explanations.

Aim. The goal of this study was to investigate the effect of guiding questions on students’ understanding of statistics.

Sample and Method. In an experimental setting, two randomly selected groups of students (N= 49) answered achievement and transfer questions on statistics as a measure of performance. Students in the intervention condition were given guiding questions to direct their way of reasoning before they answered the achievement questions. The students in the control condition were asked to write down their way of thinking before they answered the same achievement questions. In this way, both groups were stimulated to self‐explain, but only the reasoning processes of the students in the intervention condition were guided.

Results and Conclusion.  It was found that students in the intervention condition performed significantly better on achievement and transfer questions and that this effect of guidance was mediated by self‐explanations. Attitude towards statistics was positively related to performance.
Socially rejected while cognitively successful? The impact of minority dissent on groups’ cognitive complexity
Authors: Curşeu Petru Lucian , Schruijer Sandra G. L. , Boroş Smaranda
Published: April 2011

The impact of minority dissent on group‐level outcomes is explained in the current literature by two opposing mechanisms: first, through cognitive gains due to a profound change induced by minority members in the individual cognitions of the majority members, and second, through socio‐affective process losses due to social rejection and relationship conflict. Groups are most effective in information processing if they succeed in solving this opposition and reduce the negative impact of process losses. The present study addresses this opposition using an experimental design in which we crossed minority dissent (presence vs. absence of minority dissent) with change in membership (groups with vs. groups without change in membership) to determine which condition leads to the highest group cognitive complexity. Our results show that groups with a history of dissent and where the deviant left the group have the highest cognitive complexity, followed by groups that experienced dissent and where no change in group membership took place. The groups without a history of dissent have the lowest cognitive complexity.
The Alperin Weight Conjecture and Dade's Conjecture for the Simple Group Fi′24
Authors: An Jianbei , Cannon John J. , O'Brien E. A. , Unger W. R.
Published: April 2011

We classify the radicalp-subgroups and chains of the Fischer simple group Fi′24and then verify the Alperin weight conjecture and the Uno reductive conjecture for Fi′24.
Ranks of Elliptic Curves Over Function Fields
Authors: Lauder Alan G. B.
Published: April 2011

We present experimental evidence to support the widely held belief that one half of all elliptic curves have infinitely many rational points. The method used to gather this evidence is a refinement of an algorithm due to the author which is based upon rigid and crystalline cohomology.
Computing Minimal Polynomials of Matrices
Authors: Neunhöffer Max , Praeger Cheryl E.
Published: April 2011

We present and analyse a Monte-Carlo algorithm to compute the minimal polynomial of ann × nmatrix over a finite field that requiresO(n3) field operations andO(n) random vectors, and is well suited for successful practical implementation. The algorithm, and its complexity analysis, use standard algorithms for polynomial and matrix operations. We compare features of the algorithm with several other algorithms in the literature. In addition we present a deterministic verification procedure which is similarly efficient in most cases but has a worst-case complexity ofO(n4). Finally, we report the results of practical experiments with an implementation of our algorithms in comparison with the current algorithms in the GAP library.
Effects of an Axisymmetric Contoured Endwall on a Nozzle Guide Vane: Adiabatic Effectiveness Measurements
Authors: Thrift A. A. , Thole K. A. , Hada S.
Published: April 2011

Gas turbine designs seek improved performance by modifying the endwalls of nozzle guide vanes in the engine hot section. Within the nozzle guide vanes, these modifications can be in the form of an axisymmetric contour as the area contracts from the combustor to the turbine. This paper investigates the effect of axisymmetric endwall contouring on the cooling performance of a film cooled endwall. Adiabatic effectiveness measurements were performed in a planar passage for comparison to a contoured passage, whereby the exit Reynolds numbers were matched. For the contoured passage, measurements were performed both on the flat endwall and on the contoured endwall. Fully expanded film cooling holes were distributed on the endwall surface preceded by a two-dimensional slot normal to the inlet axis. Results indicated that the coolant coverage from the upstream leakage slot was spread over a larger area of the contoured endwall in comparison to the flat endwall of the planar passage. Film cooling effectiveness on the flat endwall of the contoured passage showed minimal differences relative to the planar passage results. The contracting endwall of the contoured passage, however, showed a significant reduction with average film cooling effectiveness levels approximately 40% lower than the planar passage at low film cooling flow rates. In the case of all endwalls, increasing leakage and film cooling mass flow rates led to an increase in cooling effectiveness and coolant coverage.
Divide and Conquer: Teasing Out the Cause of Heart Defects in Down Syndrome
Authors: Farrell Ruth M.
Published: April 2011

Individual genetic mutations may contribute to the distinct conditions that make up Down syndrome.
Breast Cancer Imaging Goes Green
Authors: Tridandapani Srini
Published: April 2011

Near-infrared imaging of the breasts after intravenous injection of indocyanine green distinguishes benign from malignant lesions.
Relative Contributions of Ebp Pili and the Collagen Adhesin Ace to Host Extracellular Matrix Protein Adherence and Experimental Urinary Tract Infection by Enterococcus faecalis OG1RF
Authors: Nallapareddy Sreedhar R. , Singh Kavindra V. , Sillanpää Jouko , Zhao Meng , Murray Barbara E.
Published: April 2011

Previous studies have demonstrated that the
ebp
operon and the
ace
gene of
Enterococcus faecalis
, encoding
e
ndocarditis- and
b
iofilm-associated
p
ili and an
a
dhesin to
c
ollagen of

E

. faecalis
, respectively, are both important in experimental urinary tract infections (UTI) and endocarditis. We have also shown that growth of
E. faecalis
in brain heart infusion (BHI) serum enhances Ebp pilus and Ace production and increases adherence to several host extracellular matrix proteins. Here, we report that deletion of
ebpABC
almost eliminated serum-elicited adherence to fibrinogen (
P
< 0.0001), resulted in moderate reduction in adherence to collagen (
P
< 0.05), and had no effect on fibronectin adherence relative to that of wild-type OG1RF. An OG1RFΔ
ace
Δ
ebpABC
double mutant showed further reduced collagen adherence versus that of the OG1RFΔ
ace
or OG1RFΔ
ebpABC
mutants (
P
< 0.001). These results were corroborated by complementation and/or studies with native pilus-enriched surface extracts and a collagen-secreting 3T6 fibroblast cell line, as well as antibody inhibition. In the UTI model, both the OG1RFΔ
ace
and OG1RFΔ
ace
Δ
ebpABC
mutants were found to be significantly attenuated compared to the wild type; however, no significant differences were observed between individual
ace
or
ebp
mutants and the OG1RFΔ
ace
Δ
ebpABC
mutant. In summary, these data implicate the Ebp pili as having some role in collagen adherence, albeit less than that of Ace, and a very major role in fibrinogen adherence, which may explain in part the importance of these pili in experimental endocarditis. The OG1RFΔ
ace
Δ
ebpABC
mutant was attenuated in the UTI model, although not significantly more so than the Δ
ace
or Δ
ebpABC
mutants, suggesting involvement of other
E. faecalis
factors in urinary tract colonization or infection.
Transcriptome of Proteus mirabilis in the Murine Urinary Tract: Virulence and Nitrogen Assimilation Gene Expression
Authors: Pearson Melanie M. , Yep Alejandra , Smith Sara N. , Mobley Harry L. T.
Published: April 2011

The enteric bacteriumProteus mirabilisis a common cause of complicated urinary tract infections. In this study, microarrays were used to analyzeP. mirabilisgene expressionin vivofrom experimentally infected mice. Urine was collected at 1, 3, and 7 days postinfection, and RNA was isolated from bacteria in the urine for transcriptional analysis. Across nine microarrays, 471 genes were upregulated and 82 were downregulatedin vivocompared toin vitrobroth culture. Genes upregulatedin vivoencoded mannose-resistantProteus-like (MR/P) fimbriae, urease, iron uptake systems, amino acid and peptide transporters, pyruvate metabolism enzymes, and a portion of the tricarboxylic acid (TCA) cycle enzymes. Flagella were downregulated. Ammonia assimilation geneglnA(glutamine synthetase) was repressedin vivo, whilegdhA(glutamate dehydrogenase) was upregulatedin vivo. Contrary to our expectations, ammonia availability due to urease activity inP. mirabilisdid not drive this gene expression. AgdhAmutant was growth deficient in minimal medium with citrate as the sole carbon source, and loss ofgdhAresulted in a significant fitness defect in the mouse model of urinary tract infection. UnlikeEscherichia coli, which repressesgdhAand upregulatesglnAin vivoand cannot utilize citrate, the data suggest thatP. mirabilisuses glutamate dehydrogenase to monitor carbon-nitrogen balance, and this ability contributes to the pathogenic potential ofP. mirabilisin the urinary tract.
Mua (HP0868) Is a Nickel-Binding Protein That Modulates Urease Activity in Helicobacter pylori
Authors: Benoit Stéphane L. , Maier Robert J.
Published: April 2011

A novel mechanism aimed at controlling urease expression in
Helicobacter pylori
in the presence of ample nickel is described. Higher urease activities were observed in an
hp0868
mutant (than in the wild type) in cells supplemented with nickel, suggesting that the HP0868 protein (herein named Mua for
m
odulator of
u
rease
a
ctivity) represses urease activity when nickel concentrations are ample. The increase in urease activity in the Δ
mua
mutant was linked to an increase in urease transcription and synthesis, as shown by quantitative real-time PCR, SDS-PAGE, and immunoblotting against UreAB. Increased urease synthesis was also detected in a Δ
mua
Δ
nikR
double mutant strain. The Δ
mua
mutant was more sensitive to nickel toxicity but more resistant to acid challenge than was the wild-type strain. Pure Mua protein binds 2 moles of Ni
2+
per mole of dimer. Electrophoretic mobility shift assays did not reveal any binding of Mua to the
ureA
promoter or other selected promoters (
nikR
,
arsRS
,
5′ ureB
-sRNAp). Previous yeast two-hybrid studies indicated that Mua and RpoD may interact; however, only a weak interaction was detected via cross-linking with pure components and this could not be verified by another approach. There was no significant difference in the intracellular nickel level between wild-type and
mua
mutant cells. Taken together, our results suggest the HP0868 gene product represses urease transcription when nickel levels are high through an as-yet-uncharacterized mechanism, thus counterbalancing the well-described NikR-mediated activation.

IMPORTANCE
Urease is a nickel-containing enzyme that buffers both the cytoplasm and the periplasm of
Helicobacter pylori
by converting urea into ammonia and carbon dioxide. The enzyme is the most abundant protein in
H. pylori
, accounting for an estimated 10% of the total protein content of the cell, and it is essential for early colonization and virulence. Numerous studies have focused on the transcription of the structural
ureAB
genes and its control by the regulatory proteins NikR and ArsR. Here we propose that urease transcription is under the control of another Ni-binding protein besides NikR, the Mua (HP0868) protein. Our results suggest that the Mua protein represses urease transcription when nickel levels are high. This mechanism would counterbalance the NikR-mediated activation of urease and ensure that, in the presence of a high nickel concentration, urease activation is limited and does not lead to massive production of detrimental ammonia.
Concussion information online: evaluation of information quality, content and readability of concussion-related websites
Authors: Ahmed Osman H , Sullivan S John , Schneiders Anthony G , McCrory Paul R
Published: April 2011

Background

The internet plays an important role in the dissemination of health information to the general public. Information on orthopaedic sports medicine websites has been shown to be of a varying standard, and to date there has been no evaluation of the overall quality of concussion-related websites.

Methods

A four-stage methodological sampling technique was used to identify concussion-related websites. Websites were assessed for the presence of a quality standard (theHONcode), their adherence to current expert concussion knowledge using a custom-developed concussion checklist ('CONcheck'), and their readability using the established Flesch Reading Ease (FRE) and Flesch–Kincaid Grade Level (FKGL).

Results

43 Websites were identified from the search strategy with the majority (70%) notHONcodecertified. A wide distribution of scores was seen for the CONcheck (0–22), FRE (16.3–77.4) and FKGL (6–17.8). Statistical analysis using independent t tests between websites with theHONcodeand websites without theHONcodeshowed no significant differences between the two groups for CONcheck (t41=0.571, p=0.571), FRE (t41=0.808, p=0.424) and FKGL(t41=−0.964, p=0.341) scores.

Conclusions

The variability in the standard of concussion-related websites highlights the need for sports medicine website providers to consider the delivery, content and readability of information to the public.
Harris, harmed states, and sexed bodies
Authors: Sparrow Robert
Published: April 2011

This paper criticises John Harris's attempts to defend an account of a ‘harmed condition’ that can stand independently of intuitions about what is ‘normal’. I argue that becauseHomo sapiensis a sexually dimorphic species, determining whether a particular individual is in a harmed condition or not will sometimes require making reference to the normal capacities of their sex. Consequently, Harris's account is unable to play the role he intends for it in debates about the ethics of human enhancement.
Middle meningeal artery arising from the basilar artery: report of a case and its probable embryological mechanism: Figure 1
Authors: Kumar Subhash , Mishra Nalin K
Published: April 2011

An extremely rare variation of the (left) middle meningeal artery (MMA) originating from the basilar artery, detected incidentally during cerebral angiography, is reported. The right MMA was normal and an accessory meningeal artery arising from the maxillary artery was present on both the sides. The foramen spinosum on the variant side was absent. This abnormal origin of the MMA can be explained by the presence of a perineural arterial network in the region of the Gasserian ganglion, formed by branches of the developing basilar and stapedial arterial systems; the middle meningeal–basilar arterial channel opening up in the absence of a normally developing MMA.
Social responsibility in tobacco production? Tobacco companies' use of green supply chains to obscure the real costs of tobacco farming
Authors: Otañez Marty , Glantz Stanton A
Published: April 2011

Background

Tobacco companies have come under increased criticism because of environmental and labour practices related to growing tobacco in developing countries.

Methods

Analysis of tobacco industry documents, industry websites and interviews with tobacco farmers in Tanzania and tobacco farm workers, farm authorities, trade unionists, government officials and corporate executives from global tobacco leaf companies in Malawi.

Results

British American Tobacco and Philip Morris created supply chains in the 1990s to improve production efficiency, control, access to markets and profits. In the 2000s, the companies used their supply chains in an attempt to legitimise their portrayals of tobacco farming as socially and environmentally friendly, rather than take meaningful steps to eliminate child labour and reduce deforestation in developing countries. The tobacco companies used nominal self-evaluation (not truly independent evaluators) and public relations to create the impression of social responsibility. The companies benefit from $1.2 billion in unpaid labour costs because of child labour and more than $64 million annually in costs that would have been made to avoid tobacco-related deforestation in the top 12 tobacco growing developing countries, far exceeding the money they spend nominally working to change these practices.

Conclusions

The tobacco industry uses green supply chains to make tobacco farming in developing countries appear sustainable while continuing to purchase leaf produced with child labour and high rates of deforestation. Strategies to counter green supply chain schemes include securing implementing protocols for the WHO Framework Convention on Tobacco Control to regulate the companies' practices at the farm level.
Differential growth ofFusarium moniliformerelative to tissues from 'Silver Queen', a sweet maize
Authors: Yates I E , Jaworski A J
Published: April 2011

Vegetative and reproductive tissues of maize, Zea mays L., were inoculated in vitro with Fusarium moniliforme J. Sheld. to determine inherent differences among plant tissue types to support mycelia proliferation. The F. moniliforme isolate used for inoculations was tagged with gusA, a reporter gene, providing evidence that developing mycelia were from the inoculum source and excluding possibilities of an external contaminant or an internal endophytic F. moniliforme. Vegetative tissues were dissected from roots, stems, and leaves; reproductive tissues were dissected from developing male and female inflorescences and fruits. In addition, mycelial development was analyzed on nonwounded and wounded mature kernels. Fusarium moniliforme mycelial accumulation was more rapid and extensive on reproductive than on vegetative plant tissue. Fusarium moniliforme conidia inoculated on immature kernels formed a dense mycelial mat, whereas F. moniliforme conidia inoculated on mature kernels developed sparse hyphae, unless the kernels had been wounded. Thus, the type, maturity, and physical condition of maize plant tissues are factors responsible for in vitro differences in mycelial proliferation.Key words: conidia, mycotoxins, plant pathogen, reproductive tissue, vegetative tissue, Zea mays.
Analysis of restriction fragment length polymorphisms in the ribosomal DNA of a selection of anaerobic chytrids
Authors: Hausner G , Inglis G D , Yanke L J , Kawchuk L M , McAllister T A
Published: April 2011

Anaerobic chytrid strains (representing four genera and seven species based on morphological characters), obtained from a variety of hosts, were analysed for variability within the 5' terminal segment of the ribosomal large subunit (LSU) gene, first internal transcribed spacer (ITS1), and the intergenic spacers (IGS) of the ribosomal repeat unit. In the analyses of the ribosomal LSU gene, strains of Neocallimastix, Orpinomyces, and Anaeromyces clustered into distinct groups, but Piromyces strains did not. Although the size of polymerase chain reaction products for the ITS1 region varied among strains, restriction fragment length polymorphism analysis was not useful in distinguishing between the strains. In the analyses of restriction fragment profiles of the IGS, strains of Orpinomyces and Anaeromyces clustered into distinct groupings that corresponded with morphological characters. In contrast, Neocallimastix strains clustered into two distinct groups. Considerable variability was observed in the IGS for strains of Piromyces. Analysis of this region split strains of Piromyces rhinzinflata obtained from a single bison into at least two distinct genetic groupings. Furthermore, the Piromyces strains obtained from bovine, wapiti, and moose clustered according to host. Overall, our molecular data suggest that morphological characters as observed under the light microscope are insufficient for the designation of phylogenetic species of Neocallimastix and Piromyces, and that integration of molecular and morphological data will be required to establish a natural classification system for the anaerobic members of the Chytridiomycota.Key words: anaerobic fungi, rumen, Chytridiomycota, ribosomal DNA, RFLP.
Effect of elevated carbon dioxide in the root atmosphere on nitrogenase activity in three actinorhizal plant species
Authors: Schwintzer Christa R , Tjepkema John D
Published: April 2011

In wet soils, nitrogen-fixing root nodules are subjected to elevated CO2. Only a few studies have examined the effect of elevated CO2 on nitrogenase activity, and the results have been mixed. We examined intact black alder (Alnus glutinosa (L.) Gaertn.) and sweet gale (Myrica gale L.) seedlings and field-collected speckled alder (Alnus incana ssp. rugosa (Du Roi) Claus.) nodules to clarify the effects of elevated CO2. Nitrogenase activity was measured via acetylene reduction in an open, flow-through system. We found that repeated measurements of the peak rate of nitrogenase activity, the only reliable measure of nitrogenase activity, could be made on the same plant via 150-s exposures to acetylene separated by 20 min without acetylene. Our results for elevated CO2 consistently showed that it had little effect on nitrogenase activity at low concentrations and increasingly inhibited nitrogenase activity as the CO2 concentration increased. In black alder, 0.5 kPa CO2 had little effect, whereas 3.0 kPa CO2 reduced nitrogenase activity 3135%. Sweet gale, was less sensitive to elevated CO2 and was unaffected by 1.5 kPa CO2. Black alder grown with the roots, but not the shoots, in 1.3 kPa CO2 showed only minimal acclimation to elevated CO2.Key words: acetylene reduction technique, actinorhizal plants, Alnus, carbon dioxide, Myrica gale, nitrogen fixation.
Clonal development of Maianthemum dilatatum in forests of differing age and structure
Authors: Lezberg Ann L , Halpern Charles B , Antos Joseph A
Published: April 2011

The development of a dense tree layer in young coniferous stands can suppress understory plants, leading to very low herb abundance and diversity. In this study, clonal development of the rhizomatous herb Maianthemum dilatatum (Wood) Nels & Macbr. was compared among four types of coniferous forest (young, closed canopy; young, silviculturally thinned; mature; and old growth) on the western Olympic Peninsula, Washington. We predicted that (i) ramet turnover would be lowest, (ii) clonal fragment size would be smallest, and (iii) allocation of resources to leaves would be greatest in young, closed-canopy forests, and that these traits would increase (or decrease for leaves) as understory conditions became more favorable with stand development or thinning. The low frequency of new ramets in young, closed-canopy stands supported the first prediction. The second prediction was also supported: lateral spread and rhizome mass were smallest in these stands. However, allocation to leaves was not higher in dense young stands, indicating that Maianthemum does not respond to stress by increased investment in leaves. Clonal fragments in thinned, mature, and old stands showed no differences in traits, suggesting that once tree canopies rise, canopy gaps form, or young stands are thinned, resource levels are favorable for clonal growth. Maianthemum appears to persist in dense, young stands by maintaining long-lived ramets that produce leaves annually, rather than by increasing rhizome spread, rhizome storage, or allocation to leaves.Key words: age structure, biomass allocation, canopy closure, forest herb, rhizome.
Gene sequence analysis of an opportunistic wheat pathogen, an isolate ofFusarium proliferatum
Authors: Kwon Sun-Il , Dohlen Carol D von , Anderson Anne J
Published: April 2011

A fungal endophyte of wheat causing seedling necrosis when plants are grown under stressed conditions was identified as a Fusarium proliferatum (Matsushima) Nirenberg isolate (NRRL 31017). The wheat isolate grew rapidly on potato dextrose agar as lanose to cottony colonies and rarely produced macroconidia under ultraviolet light. Microconidia were produced both in false heads and chains; sporodochia and chlamydospores were not found. Phylogenetic analysis of the nucleotide sequences of the genes for β-tubulin, mitochondrial small subunit ribosomal DNA, calmodulin, and elongation factor 1-α from the wheat isolate showed affinity with other F. proliferatum isolates. The closest relationship was with an isolate with ligninolytic potential obtained from forest litter in Spain (F. proliferatum MUCL 31970). Nucleotide sequences of genes encoding laccases, which are quite divergent between fungal species, showed 99% identity between the wheat and the forest litter isolates.Key words: Fusarium proliferatum, laccase, phylogeny, genetic variability.
Phylogenetic implications of meiosis in wild and cultivated interspecific hybrids in Chrysopsis (Compositae–Astereae): C. godfreyi (n = 5) × gossypina ssp. cruiseana (n = 9) and C. godfreyi (n = 5) × linearifolia (n = 5)
Authors: Semple J. C. , Chinnappa C. C.
Published: April 2011

Mitotic karyotypes and meiotic pairing were studied in wild, cultivated, and experimentally produced hybrids between Chrysopsis godfreyi (n = 5) and C. gossypina ssp. cruiseana (n = 9) and between C. godfreyi and C. linearifolia (n = 5). Hybrids were first detected on morphological grounds. During metaphase 1 in the amphidiploid 2n = 14 hybrids (godfreyi × cruiseana) the following associations were most frequent: 3III + 2II + 1I, 2III + 3II + 2I. During meiosis in the 2n = 10 hybrid (godfreyi × linearifolia) an association of 4II + 2I was most frequently observed. Meiotic and karyotype data indicate that an n = 5 taxon gave rise to an n = 4 taxon; these or their derivatives hybridized to yield ultimately a 2n = 18 allopolyploid taxon. Some changes in gene arrangement have occurred in the n = 9 taxa and in one n = 5 phylogenetic line, as indicated by chromosome and chromatid bridge formation in meiosis of the hybrids.
Electron microscopic study of oospore maturation and germination in an emasculate isolate of Saprolegnia ferax. 3. Changes in organelle status and associations
Authors: Beakes Gordon W.
Published: April 2011

Changes in the structure of the main cytoplasmic organelles (excluding wall and nuclei) during the formation, maturation, and germination of Saprolegnia ferax oospores have been followed by transmission electron microscopy and their status assessed by stereologic analysis of micrographs. During oosphere differentiation there is a steady accumulation of lipid and dense-body (lipo-phospho glucan complexes) reserves; at the same time the overall status quo of other organelles is maintained. Oospore maturation is associated with the coalescence of dense-body vesicles, partial utilization of neutral lipid reserves, and dramatic decline in most other cell organelles. This is preceded by a marked increase in lipid-associated microbodies (glyoxysomes) which appear to develop from the fragmentation of cisternae of smooth endoplasmic reticulum. At the onset of germination the inner oospore wall is rapidly digested and normal levels of cytoplasmic organelles is restored. The neutral lipid fraction progressively declines with half the reserves being utilized before germ tube emergence. The osmiophilic dense-body vesicle derived ooplast matrix disintegrates and dense-bodylike granules are released into the expanding central vacuole and peripheral cytoplasmic vesicles, which eventually become associated with cup-shaped mitochondria. Unusual reticular bodies (mitochondria), crystalline aggregates (virus particles), and multivesicular bodies are also described in the cytoplasm of germinating spores. The results are discussed in relation to the possible metabolic pathways associated with the utilization of endogenous reserves.
Effect of ammonia on photosynthetic carbon fixation in isolated spinach leaf cells
Authors: Woo K. C. , Canvin D. T.
Published: April 2011

Ammonia stimulated photosynthetic 14CO2 fixation in isolated spinach cells under conditions of saturating light intensity and adequate CO2 supply. Increasing temperature increased photosynthesis and promoted the stimulation of photosynthesis by ammonia. Ammonia increased carbon traffic into organic acids and amino acids without affecting the total, 14C incorporation in the neutral fraction, although the relative distribution of 14C incorporation in the neutral fraction as a percentage of the total soluble 14C incorporation was decreased. The increased carbon flow into the amino acid fraction led to an increase of, 14C incorporation, principally into glutamine, glutamate, and aspartate. The role of ammonia in photosynthetic carbon metabolism is discussed.
Rare scale-bearing Chrysophyceae of Otter Lake, British Columbia
Authors: Green Roderick B.
Published: April 2011

Examination of the Chrysophyceae flora in Otter Lake, British Columbia, by electron microscopy verified the occurrence of eight scale-bearing species belonging to the genera Epipyxis, Spiniferomonas, Chrysosphaerella, Mallomonas, and Mallomonopsis. Two of the species, Epipyxis kenaiensis and Mallomonopsis paxillata, are reported from Canada for the first time. This report also includes notes on the taxonomy and distribution of the eight species of Chrysophyceae and basic limnological data for Otter Lake.
Contractile proteins from the tomato
Authors: Vahey Maryanne , Scordilis Stylianos P.
Published: April 2011

Proteins exhibiting all of the basic structural and biochemical characteristics of actin and myosin have been isolated from the parenchymal cells of the fruit of the tomato, Lycopersicon esculentum. Crude cytoplasmic extracts of these cells contain filaments that can be decorated by rabbit skeletal muscle myosin subfragment-1 (S-1). Polymerized tomato actin activates the Mg2+–ATPase of both skeletal and tomato myosin at physiological ionic strength. Tomato actin comigrates with skeletal actin on sodium dodecyl sulfate polyacrylamide gels (SDS-PAGE) indicating an apparent molecular weight of 45 000. High ionic strength extracts of tomato contain a myosin whose ATPase activity in 0.5 M KCl is maximal in the presence of K+-ethylenediaminetetraacetic acid (K+-EDTA) and is inhibited by Mg2+. Tomato myosin interacts with skeletal F-actin to form an actomyosin complex that can be dissociated by ATP. At low ionic strength the Mg2+–ATPase of the myosin can be activated by actin.
Comparaison de différents milieux utilisés en culture d'anthères in vitro chez le Blé tendre
Authors: Buyser Jacques De , Henry Yves
Published: April 2011

Three culture media, including one from potato extracts, have been compared. It is shown that glutamine and the potato extract medium increase the frequency of embryos produced from anther cultures. On the other hand, the extract medium is characterized by (1) the earlier formation of embryos; (2) better embryos which most often have meristematic initials; and (3) an increase in the rate of haploids. [Journal translation]
Observations sur le développement des bourgeons des balais de sorcière du Prunier
Authors: Dreger-Jauffret Françoise
Published: April 2011

Observation of the development of the buds on plum-tree witches' brooms provoked by Taphrina insititiae (Sad.) Johans. showed that the form of the witches' broom results from a balance between a surplus of vigor and a tendency to die, two opposing characteristics that are related to the parasitism. In addition, experiments in which shoots or isolated nodes were forced showed that the inhibition of bud opening observed in healthy plum-tree buds once they have entered the resting state is only potential in diseased shoots.
Chemotaxonomic studies in the Saxifragaceae s.l. 15. The flavonoids of subsection Villosae section Heuchera in the genus Heuchera
Authors: Wells Elizabeth Fortson , Bohm Bruce A.
Published: April 2011

The flavonoid constituents of Heuchera villosa var. villosa, H. parviflora var. parviflora, and H. glabra have been studied. The predominant flavonoids present in all three species were mono-, di-, and triglycosides of kaempferol, quercetin, and myricetin. Isorhamnetin, larycitrin, syringetin, and luteolin were also seen in some species. Dihydromyricetin was isolated from H. villosa. The data were compared with results obtained earlier from H. micrantha var. diversifolia and H. cylindrica. The hypothesis that evolutionary advancement and ecological specialization in the genus are accompanied by a simplification in the glycoside pattern was proposed.
Ultrastructure of Synchytrium macrosporum zoospores
Authors: Montecillo Catalina M. , Bracker Charles E. , Powell Martha J.
Published: April 2011

The ultrastructure of the posteriorly uniflagellate zoospores of Synchytrium macrosporum Karling, an obligate plant parasitic Chytridiomycete with a wide host range, is described. The zoospore possesses characteristic and intricate internal organellar associations involving the nucleus, mitochondria, microbody, lipid globule, endoplasmic reticulum, rumposome, and Golgi apparatus. The nucleus is in the anterior portion of the cell, and the lipid globule is in the posterior region. A complex microbody is between the nucleus and the lipid globule and branches out to partly encircle the nucleus, the lipid globule, and the mitochondria. A well-developed rumposome is in the posterior half of the cell, but a nuclear cap is absent. The rumposome is continuous with the rough endoplasmic reticulum, and is associated with a single dictyosome near the kinetosome. The rumposome encapsulates most of the exposed surface of the posterior portion of the lipid globule. Vacuoles have various shapes and contents, including some with the appearance of gamma bodies seen in other chytrids. A system of branched knobbed props links the kinetosome to the plasma membrane of the zoospore. The kinetosome and the secondary centriole are transversely striated, but no terminal plate is present. This study shows that the zoospore of S. macrosporum has a distinctive cell organization as compared with Synchytrium endobioticum and other chytrid zoospores.
Relationship between levels of copper, uranium, and lead in glacial sediments and in Vaccinium uliginosum at an arctic site enriched with heavy metals
Authors: DiLabio R. N. W. , Rencz A. N.
Published: April 2011

Vaccinium uliginosum L. (bog blueberry), its mineral soil substrate, and the till on which the soil is developed were sampled at a site of uranium–copper–lead mineralization in the tundra of the central District of Keewatin. Levels of Cu and U in till result from dispersal of minerals glacially eroded from a metal-rich bedrock source. The pattern strongly expressed for Cu and U up to 1500 m from the source is not readily detectable for Pb.Concentrations of ashed Vaccinium uliginosum growing on till ranged from 0.4 to 980 ppm U, 4.5 to 3973 ppm Cu, and 0.1 to 3964 ppm Pb, values greater than previously recorded for the species. The concentrations of U and Cu were significantly correlated to metal levels in till with r = 0.98 for uranium and; r = 0.78 for copper. Data did not permit statistical analysis of soil Pb versus plant Pb.
The fine structure of zoospores of Harpochytrium hedinii
Authors: Gauriloff Larry P. , Delay Rona J. , Fuller Melvin S.
Published: April 2011

The fine structure of the Harpochytrium hedinii Wille zoospore is reexamined using serial sections. All of the major organelles are located in the posterior two-thirds of the zoospore; the anterior region contains only a few vacuoles and a network of filaments. The basal body complex is located at the center of the posterior end of the zoospore. The nucleus and "nuclear cap" are located directly anterior to the basal body complex on one side of the zoospore. All of the microbodies, lipid globules, and mitochondria are arranged into a complex associated with the rumposome along the opposite side of the zoospore. A spore-wide system of cisternae, the vesicular system, is continuous throughout the posterior region of the zoospore. The overall arrangement of organelles in the H. hedinii zoospore most closely resembles the internal morphologies of certain chytridialean zoospores. This suggests that Harpochytrium may be more closely related to the chytrids than has been previously assumed.