bluuebunny/crossref_metadata_2025 huggingface dataset:
Acquisition of a Transposon Encoding Extended-Spectrum β-Lactamase SHV-12 by
Pseudomonas aeruginosa
Isolates during the Clinical Course of a Burn Patient
Authors: Uemura Shuji , Yokota Shin-ichi , Mizuno Hirotoshi , Sakawaki Eiji , Sawamoto Keigo , Maekawa Kunihiko , Tanno Katsutoshi , Mori Kazuhisa , Asai Yasufumi , Fujii Nobuhiro
Published: June 2010

Three of seven clonally related
Pseudomonas aeruginosa
strains isolated from a burn patient produced the extended-spectrum β-lactamase (ESBL) SHV-12. Its gene was flanked by two IS
26
elements with a large transposon (>24 kb). The transposon also contained at least five IS
26
elements and a gene encoding the amikacin resistance determinant aminoglycoside 6′-
N
-acetyltransferase type Ib [
aac
(
6′
)
-Ib
]. It was inserted into the gene PA5317 in the
P. aeruginosa
chromosome.
Chromosomally Encoded
bla
CMY-2
Located on a Novel SXT/R391-Related Integrating Conjugative Element in a
Proteus mirabilis
Clinical Isolate
Authors: Harada Sohei , Ishii Yoshikazu , Saga Tomoo , Tateda Kazuhiro , Yamaguchi Keizo
Published: June 2010

Integrating conjugative elements (ICEs) are mobile genetic elements that can transfer from the chromosome of a host to the chromosome of a new host through the process of excision, conjugation, and integration. Although SXT/R391-related ICEs, originally demonstrated in
Vibrio cholerae
O139 isolates, have become prevalent among
V. cholerae
isolates in Asia, the prevalence of the ICEs among Gram-negative bacteria other than
Vibrio
spp. remains unknown. In addition, SXT/R391-related ICEs carrying genes conferring resistance to extended-spectrum cephalosporins have never been described. Here we carried out a genetic analysis of a cefoxitin-resistant
Proteus mirabilis
clinical isolate, TUM4660, which revealed the presence of a novel SXT/R391-related ICE, ICE
Pmi
Jpn1. ICE
Pmi
Jpn1 had a core genetic structure showing high similarity to that of R391 and carried
xis
and
int
genes completely identical to those of R391, while an IS
10
-mediated composite transposon carrying
bla
CMY-2
was integrated into the ICE. A nucleotide sequence identical to the 3′ part of IS
Ecp1
was located upstream of the
bla
CMY-2
gene, and other genes observed around
bla
CMY-2
in earlier studies were also present. Furthermore, the nucleotide sequences of hot spot 2 and hot spot 4 in ICE
Pmi
Jpn1 showed high similarity to that of hot spot 2 in SXT
MO10
and with a part of the nucleotide sequence found in
P. mirabilis
ATCC 29906, respectively. ICE
Pmi
Jpn1 was successfully transferred to
Escherichia coli
,
Klebsiella pneumoniae
,
Salmonella enterica
serovar Typhimurium, and
Citrobacter koseri
in conjugation experiments. These observations suggest that ICEs may contribute to the dissemination of antimicrobial resistance genes among clinically relevant
Enterobacteriaceae
, which warrants careful observation of the prevalence of ICEs, including SXT/R391-related ICEs.
Investigations into the Role of the
Plasmodium falciparum
SERCA (PfATP6) L263E Mutation in Artemisinin Action and Resistance
Authors: Valderramos Stephanie Gaw , Scanfeld Daniel , Uhlemann Anne-Catrin , Fidock David A. , Krishna Sanjeev
Published: June 2010

Artemisinin-based combination therapies (ACTs) are highly effective for the treatment of
Plasmodium falciparum
malaria, yet their sustained efficacy is threatened by the potential spread of parasite resistance. Recent studies have provided evidence that artemisinins can inhibit the function of PfATP6, the
P. falciparum
ortholog of the ER calcium pump SERCA, when expressed in
Xenopus laevis
oocytes. Inhibition was significantly reduced in an L263E variant, which introduced the mammalian residue into a putative drug-binding pocket. To test the hypothesis that this single mutation could decrease
P. falciparum
susceptibility to artemisinins, we implemented an allelic-exchange strategy to replace the wild-type
pfatp6
allele by a variant allele encoding L263E. Transfected
P. falciparum
clones were screened by PCR analysis for disruption of the endogenous locus and introduction of the mutant L263E allele under the transcriptional control of a
calmodulin
promoter. Expression of the mutant allele was demonstrated by reverse transcriptase (RT) PCR and verified by sequence analysis. Parasite clones expressing wild-type or L263E variant PfATP6 showed no significant difference in 50% inhibitory concentrations (IC
50
s) for artemisinin or its derivatives dihydroartemisinin and artesunate. Nonetheless, hierarchical clustering analysis revealed a trend toward reduced susceptibility that neared significance (artemisinin,
P
≈ 0.1; dihydroartemisinin,
P
= 0.053 and
P
= 0.085; and artesunate,
P
= 0.082 and
P
= 0.162 for the D10 and 7G8 lines, respectively). Notable differences in the distribution of normalized IC
50
s provided evidence of decreased responsiveness to artemisinin and dihydroartemisinin (
P
= 0.02 for the D10 and 7G8 lines), but not to artesunate in parasites expressing mutant PfATP6.
In
Vitro
Synergism of Ciprofloxacin and Cefotaxime against Nalidixic Acid-Resistant
Salmonella enterica
Serotypes Paratyphi A and Paratyphi B
Authors: Neupane Ganesh Prasad , Kim Dong-Min , Kim Sung Hun , Lee Bok Kwon
Published: June 2010

Paratyphoid fever is considered an emerging systemic intracellular infection caused by
Salmonella enterica
serotypes Paratyphi A, B, and C. We performed
in vitro
time-kill studies on three clinical isolates of nalidixic acid-resistant
Salmonella
serotype Paratyphi (NARSP) with different concentrations of ciprofloxacin and cefotaxime to identify combinations of antibiotics with synergistic activity against paratyphoid fever. Furthermore, we identify the frequency of mutations to ciprofloxacin, cefotaxime, and rifampin resistance and also sequenced the
gyrA
,
gyrB
,
parC
, and
parE
genes to identify the cause of resistance in NARSP. When the activity of ciprofloxacin at 0.75× MIC (0.012 to 0.38 μg/ml) with cefotaxime at the MIC (0.125 to 0.25 μg/ml) against all three NARSP isolates was investigated, synergy was observed at 24 h, and the bacterial counts were reduced by >3 log
10
CFU/ml. This synergy was elongated for up to 72 h in two out of three isolates. When ciprofloxacin at 0.75× MIC (0.012 to 0.38 μg/ml) was combined with cefotaxime at 2× MIC (0.25 to 0.50 μg/ml), synergy was prolonged for up to 72 h in all three isolates. Both
Salmonella
serotype Paratyphi A isolates carried single mutations in codon 83 of the
gyrA
gene and codon 84 of the
par
C gene that were responsible for their reduced susceptibility to ciprofloxacin, while no mutations were found in the
gyrB
or
parE
gene. The ciprofloxacin-plus-cefotaxime regimen was very effective in reducing the bacterial counts at 24 h for all three isolates, and this combination therapy may be helpful in reducing the chance of the emergence of fluoroquinolone-resistant mutants in patients with severe paratyphoid fever.
Fusidic Acid Resistance Rates and Prevalence of Resistance Mechanisms among
Staphylococcus
spp. Isolated in North America and Australia, 2007-2008
Authors: Castanheira Mariana , Watters Amy A. , Bell Jan M. , Turnidge John D. , Jones Ronald N.
Published: June 2010

Among 4,167
Staphylococcus aureus
and 790 coagulase-negative
Staphylococcus
(CoNS; not
S. saprophyticus
) isolates collected consecutively from North American and Australian hospitals, only 87 (1.7% overall) isolates displayed a fusidic acid (FA; also known as CEM-102) MIC of ≥2 μg/ml (FA resistance). These strains were further evaluated with a multiplex PCR to amplify the acquired resistance genes
fusB
,
fusC
, and
fusD.
Mutations in
fusA
and
fusE
were evaluated in all isolates showing an absence of acquired resistance genes and/or showing FA MIC values of ≥64 μg/ml.
S. aureus
resistance rates were very low in the United States (0.3%) and were higher in Canada and Australia (7.0% for both countries). Among CoNS isolates, FA resistance rates were significantly more elevated than that for
S. aureus
(7.2 to 20.0%; the highest rates were in Canada). All 52 (41 CoNS) FA-resistant isolates from the United States showed FA MIC results of ≤64 μg/ml, and 7 of 11
S. aureus
isolates carried
fusC
. CoNS strains from the United States carried
fusB
or
fusC
. In Canada,
fusB
and
fusC
occurrences were similar among
S. aureus
and CoNS isolates, and modestly elevated FA MIC values were observed (all MIC results were ≤32 μg/ml). Isolates from Australia showed MIC values ranging from 2 to 32 μg/ml, and
S. aureus
isolates were predominantly
fusC
positive.
fusA
mutations were detected in only three
S. aureus
isolates, conferring FA MIC values of 2 to 8 μg/ml. Target mutations have been considered the primary FA resistance mechanism among
Staphylococcus
spp.; however, acquired resistance genes appear to have a dominant role in resistance against this older antimicrobial agent. In summary, this study shows that acquired genes are highly prevalent among FA-resistant strains (>90%) in three nations with distinct or absence (United States) of fusidic acid clinical use.
Leishmania donovaniAmastigotes Impair Gamma Interferon-Induced STAT1α Nuclear Translocation by Blocking the Interaction between STAT1α and Importin-α5
Authors: Matte Christine , Descoteaux Albert
Published: June 2010

The protozoan parasiteLeishmania donovani, the etiological agent of visceral leishmaniasis, is renowned for its capacity to sabotage macrophage functions and signaling pathways stimulated by activators such as gamma interferon (IFN-γ). Our knowledge of the strategies utilized byL. donovanito impair macrophage responsiveness to IFN-γ remains fragmentary. In the present study, we investigated the impact of an infection by the amastigote stage ofL. donovanion IFN-γ responses and signaling via the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway in mouse bone marrow-derived macrophages. The levels of IFN-γ-induced expression of major histocompatibility complex class II and inducible nitric oxide synthase (iNOS) were strongly reduced inL. donovaniamastigote-infected macrophages. As the expression of those genes is mediated by the transcription factors STAT1α and IFN regulatory factor 1 (IRF-1), we investigated their activation in amastigote-infected macrophages treated with IFN-γ. We found that whereas STAT1α protein levels and the levels of phosphorylation on Tyr701 and Ser727 were normal, IRF-1 expression was inhibited in infected macrophages. This inhibition of IRF-1 expression correlated with a defective nuclear translocation of STAT1α, and further analyses revealed that the IFN-γ-induced STAT1α association with the nuclear transport adaptor importin-α5 was compromised inL. donovaniamastigote-infected macrophages. Taken together, our results provide evidence for a novel mechanism used byL. donovaniamastigotes to interfere with IFN-γ-activated macrophage functions and provide a better understanding of the strategies deployed by this parasite to ensure its intracellular survival.
Global Gene Expression Profiling ofYersinia pestisReplicating inside Macrophages Reveals the Roles of a Putative Stress-Induced Operon in Regulating Type III Secretion and Intracellular Cell Division
Authors: Fukuto Hana S. , Svetlanov Anton , Palmer Lance E. , Karzai A. Wali , Bliska James B.
Published: June 2010

Yersinia pestis, the causative agent of plague, is a facultative intracellular pathogen. Previous studies have indicated that the ability ofY. pestisto survive inside macrophages may be critical during the early stages of plague pathogenesis. To gain insights into the biology of intracellularY. pestisand its environment following phagocytosis, we determined the genome-wide transcriptional profile ofY. pestisKIM5 replicating inside J774.1 macrophage-like cells using DNA microarrays. At 1.5, 4, and 8 h postinfection, a total of 801, 464, and 416Y. pestisgenes were differentially regulated, respectively, compared to the level of gene expression of control bacteria grown in tissue culture medium. A number of stress-response genes, including those involved in detoxification of reactive oxygen species, as well as several metabolic genes involved in macromolecule synthesis, were significantly induced in intracellularY. pestis, consistent with the presence of oxidative stress and nutrient starvation insideYersinia-containing vacuoles. A putative stress-induced operon consisting of y2313, y2315, and y2316 (y2313-y2316), and a previously unidentified open reading frame,orfX, was studied further on the basis of its high level of intracellular expression. Mutant strains harboring either deletion, Δy2313-y2316 or ΔorfX, exhibited diverse phenotypes, including reduced effector secretion by the type III secretion system, increased intracellular replication, and filamentous morphology of the bacteria growing inside macrophages. The results suggest a possible role for these genes in regulating cell envelope characteristics in the intracellular environment.
Developing injury indicators for Canadian children and youth: a modified-Delphi approach
Authors: Pike Ian , Piedt Shannon , Warda Lynne , Yanchar Natalie , Macarthur Colin , Babul Shelina , Macpherson Alison K
Published: June 2010

Objective

To develop a set of national injury indicators for Canadian children and youth which will eventually be used to reflect and monitor identified prevention priorities.

Methods

The Canadian Injury Indicators Development Team brought together injury researchers, policy makers, and practitioners to develop injury indicators in the following areas: overall health services implications; motor vehicle occupant; sports, recreation, and leisure; violence; and trauma care, quality, and outcomes. A modified-Delphi process was used to establish a set of indicators that met evidence-based criteria, were useful, and that would prompt action. Each indicator was rated by 132 respondent injury experts and stakeholders on itsusefulnessand ability toprompt actionto reduce injury among Canadian children and youth.

Results

From an initial list of 51 indicators, a refined set of 34 indicators was established. Indicators were grouped into three categories related to: policies; risk and protective factors; and outcomes. Indicators related to motor vehicle injury were rated as mostusefuland most able toprompt action. Injury mortality rate and injury hospitalisation rate were also rated highly for bothusefulnessand ability toprompt action. Policy, violence, sport and recreation, and trauma indicators were all rated higher forusefulness, but somewhat lower for ability toprompt action.

Conclusion

Results suggest that a broad-based modified-Delphi process is an important first step in developing useful and relevant indicators for injury prevention activity focused on Canadian children and youth.
Use of monoclonal antibodies to detect a phytotoxic glycopeptide produced by Ophiostoma ulmi, the Dutch elm disease pathogen
Authors: Benhamou Nicole , Ouellette G. B. , Lafontaine J. G. , Joly J. R.
Published: June 2010

Two hybridomas that secrete antibodies specific for a phytotoxic glycopeptide from Ophiostoma ulmi (Buism.) Nannf. were produced by fusing spleen cells of mice immunized with the purified toxin and the Sp2-0/Ag14 mouse myeloma cell line. Specificity of these antibodies was first demonstrated by an enzyme-linked immunosorbent assay (ELISA), then by immunoblotting on nitrocellulose membrane after sodium dodecyl sulfate – polyacrylamide gel electrophoresis of the glycopeptide. Both clones produced antibodies of IgM class as determined by immunodiffusion. These monoclonal antibodies were utilized to detect and localize the toxic glycopeptide in pathogen cells and infected host tissues by immunohistochemical and immunocytochemical techniques.
Endomycorrhizal colonization of glasshouse-grown wheat as influenced by fertilizer salts when banded or soil-mixed
Authors: Davis E. Anne , Young J. L.
Published: June 2010

Seven different species from three genera of common vesicular–arbuscular mycorrhizal (VAM) fungi differed in the extent of their root colonization and in their effect on growth of winter wheat when applied in combination with different forms of nitrogen ([Formula: see text] vs. [Formula: see text]) and fertilizer anions (Cl−, [Formula: see text], [Formula: see text]), treatments that influence other soil fungi such as the take-all disease organism, Gaeumannomyces graminis tritici. Banded fertilizer salts, singly and in combinations, were more inhibitory to root colonization by most VAM species than were incorporated salts. [Formula: see text] salts were more inhibitory to both wheat growth and VAM development than were [Formula: see text] salts. Two Glomus species, G. clarum and G. fasciculatum, appeared to be salt tolerant, developing abundant vesicles, hyphae, and colonizations to near 50% in the presence of incorporated (NH4)2SO4 or NH4Cl. However, colonizations often were not indicative of growth responses; e.g., colonizations of 10% by Gigaspora gilmorei or 20 to 40% by Glomus species often depressed growth, whereas 5 to 10% colonization by Acaulospora spinosa in the presence of NH4Cl + KCl stimulated growth significantly. The effect of Cl− (with [Formula: see text]) in suppressing the pathogenic take-all fungus did not occur with symbiotic VAM fungi. The results indicate the relative effectiveness of certain species in tolerating liberal fertilization as well as their potential for stimulating or depressing plant growth.
Five Paraphysomonas species (Chrysophyceae) new to North America, with notes on three other rarely reported species
Authors: Nicholls K. H.
Published: June 2010

Five species of Paraphysomonas (P. diademifera (Takahashi) Preisig & Hibberd, P. poteriophora Moestrup & Kristiansen, P. stelligera Preisig & Hibberd, P. subquadrangularis Preisig & Hibberd, and P. subrotacea Thomsen) have been found in Ontario, Canada; they have not been reported previously from North America. The taxonomic status off P. elegantissima Kling & Kristiansen is not clearly defined and scale morphology of this species could possibly be included within the range of form now known for P. takahashii Cronberg & Kristiansen; nevertheless it is proposed to recognize the two separate taxa at least until more specimens from other localities, including those possessing unperforated plate scales, have been examined.
The distribution of Xyris difformis along a gradient of exposure to waves: an experimental study
Authors: Wilson Scott D. , Keddy Paul A. , Randall Deborah L.
Published: June 2010

The distribution of a shoreline macrophyte, Xyris difformis, was measured along a gradient of exposure to wave action in several central Ontario lakes. Its abundance changed significantly along the exposure gradient (p < 0.001). Xyris difformis occurred most frequently on shores of intermediate exposure. This distribution pattern could result from (i) maximum growth rates on intermediate-exposed shores or (ii) competitive displacement from less exposed, sheltered shores that have little disturbance, high nutrient concentrations, and dense vegetation. We attempted to distinguish between these two mechanisms by growing ramets of X. difformis in the absence of neighbours (potential competitors) along the exposure gradient on a lakeshore and measuring the accumulated biomass after one growing season. Biomass varied with position on the exposure gradient (p < 0.01). Maximum biomass was accumulated on shores of intermediate and high exposure. In another experiment, seeds of X. difformis germinated on substrates from both ends of the exposure gradient at several water depths. The proportion of seeds germinating below the waterline on substrates from sheltered shores was significantly lower than the proportion germinating on substrates from exposed shores, suggesting that seeds of X. difformis may have low germination ability on sheltered shores. The shoreline distribution of X. difformis along the exposure gradient is consistent with its physiological response curve along the gradient.
Electrophoretic and allometric variation in burdock (Arctium spp.): hybridization and its ecological implications
Authors: Rollo C. David , MacFarlane J. D. , Smith B. S.
Published: June 2010

Allometric variation and insect seed predation among Arctium minus, A. lappa, and two possible hybrids were quantified. All four biotypes were also examined using isoelectric focusing, and differences among their proteins were found for alkaline phosphatases, leucine amino peptidases, esterases, and peroxidases. The allometric and electrophoretic results indicated that hybridization between A. minus and A. lappa is very common. The implications for the population dynamics of Arctium are discussed. The parental species are probably maintained by the combined effects of differential insect predation on the seeds, differential dispersal of seeds, and reduced seed viability in hybrids.
Variation and climatic adaptation in northern populations of Datura stramonium
Authors: Weaver Susan E. , Dirks Victor A. , Warwick Suzanne I.
Published: June 2010

Between- and within-population variation for 21 quantitative characters was estimated for five populations of Datura stramonium originating along a climatic gradient ranging from southern Ohio, U.S.A., to Elgin County, Ont., Canada. Datura stramonium is a predominantly inbreeding, annual species with a distribution which is expanding northward in Ontario. Plants were grown from seed to maturity in the greenhouse under uniform conditions. The five populations differed significantly in the mean values of all measured characters. Canonical variates analyses were used to distinguish the populations on the basis of combined groups of characters. Canonical means of the five populations differed significantly for both seedling and mature plant characters, but the relative distance between populations varied for the two character sets. Levels of between- and within-family variation differed significantly among populations and from one character to another. Percent germination, seedling dry weight, and leaf area were strongly correlated with initial seed weight. Seed weight and cotyledon length increased and days to anthesis decreased with a decreasing length of the growing season.
Studies in Crataegus. XII. Cytological evidence for sexuality in some diploid and tetraploid species of North American hawthorns
Authors: Muniyamma M. , Phipps J. B.
Published: June 2010

Sexual development of the embryo sac has been demonstrated for five common (C. monogyna Jacq., C. punctata Jacq., C. mollis (T. & G.) Scheele, C. macrosperma Ashe, and C. calpodendron (Ehrh.) Medic.) and one rare (C. suborbiculata Sarg.) species of Crataegus (Rosaceae). These represent 6 of the 20 or so different Crataegus series in North America. All except C. suborbiculata (tetraploid) and C. macrosperma (tetraploid) are from diploid (2n = 34) accessions. Evidence from variation patterns known for the species discussed suggests that C. monogyna and C. punctata will be wholly or largely sexual outbreeders in North America; C. calpodendron will be mainly sexual; C. macrosperma will be a mix of agamospermic and sexual forms; and C. suborbiculata will be mainly apomictic. The bearing of this on North American Crataegus taxonomy is discussed.
An extended range for oak wilt and Ceratocystis fagacearum compatibility types in the United States
Authors: Appel D. N. , Drees C. Frost , Johnson J.
Published: June 2010

Oak wilt, caused by Ceratocystis fagacearum (Bretz) Hunt, has been found in 31 Texas counties, significantly extending the southern range of the disease in the United States. The 101 isolates obtained from 76 diseased oaks in 22 of those counties were assayed for sexual compatibility using a paired plug or spermatizing technique. There were 51 type A isolates and 44 type B isolates; 6 of the isolates could not be typed. A majority of multiple-tree infection centers contained only one compatibility type and only one diseased tree yielded both compatibility types. The distribution of compatibility types and behavior of C. fagacearum in Texas are consistent with those observed in other states.
Étude de la réactivation cambiale chez un arbre ayant un bois à zones poreuses (Castanea sativa) et deux autres au bois à pores diffus (Betula verrucosa, Acer campestre)
Authors: Boutin Bertille
Published: June 2010

Cambial reactivation and xylogenesis have been studied in diffuse porous (Betula verrucosa Ehr., Acer campestre L.) and ring porous (Castanea sativa Mill.) trees more than 25 years old. Our results show that the basipetal and overall cambial reactivations coexist in the two groups of trees, in contrast to what is generally admitted. The basipetal cambial reactivation occurs in the terminal parts of the branches and is controlled by the buds. The overall cambial reactivation affects the trunk and the older parts of the branches; it shows a certain autonomy from the phenomena occurring within the upper part of the tree.
A new tetraploid species of Avena discovered in Morocco
Authors: Baum Bernard R. , Fedak George
Published: June 2010

A newly discovered tetraploid oat species from Morocco is described morphologically and karyotypically. Some important morphological and karyotypical features are stressed and documented. Its main features are summarized with those of its allied species, Avena canariensis and Avena atlantica. Its habitat and distribution are also described.
The development, structure, and histochemistry of sclerotia of ectomycorrhizal fungi. I. Pisolithus tinctorius
Authors: Grenville D. J. , Peterson R. L. , Piché Y.
Published: June 2010

Sclerotia were produced by growing Pisolithus tinctorius (Pers.) Coker and Couch in association with Pinus strobus L. and Pinus resinosa Ait. in plastic growth pouches. Developing and mature sclerotia were collected, fixed, and embedded for light microscopy and scanning and transmission electron microscopy. They were found to consist of an outer pigmented rind, an inner and outer cortex, and a large central medulla. Cortical and medullary areas were comprised of pseudoparenchyma which contained large deposits of glycogen, as well as protein and lipids. The structure of these sclerotia indicates that they are persistent propagules. Sclerotia may be important in nature for the recolonization of root tips after environmental stresses. They may also be useful for storing valuable strains of P. tinctorius and as a source of inoculum for experimental studies.
Anatomie florale de Monstera deliciosa (Araceae)
Authors: Barabé Denis , Chrétien Louise
Published: June 2010

The flower of Monstera deliciosa has a two-carpellate, two-locular gynoecium. Placentation is axile. At the basis of the gynoecium, six to eight carpellary bundles are distinguishable. These bundles split once or several times before reaching the ovarian wall, so that midway up the ovary, about 30 bundles arranged in two circles are found. In the center of the septum, a placentary column rises up to the level of attachment of the four anatropous ovules located in the lower part of the ovary. In the upper portion of the ovary, trichosclereids are found. The vasculature of the flower of Monstera has much in common with that of Rhaphidophora.
Standing crop of Sagittaria in the Upper Mississippi River
Authors: Clark William R. , Clay Robert T.
Published: June 2010

Aboveground and belowground standing crops of Sagittaria latifolia and Sagittaria rigida were related to water depths and substrate particle-size distribution, in differing parts of Pool 9 of the Upper Mississippi River. Average water depth during the growing season was greater in stands in open-water areas (30.1 ± 2.1 cm) than in backwaters (16.5 ± 1.5 cm). The average water depth of 35.1 in S. rigida stands was deeper than the average of 26.4 cm in S. latifolia beds. Sediments in backwaters had significantly greater proportions of clay- and silt-sized particles than sediments in open waters. Density of S. latifolia in open water was 31.0 ± 1.3 compared with 22.7 ± 1.6/m2 in backwaters. Peak aboveground standing crop of S. latifolia in open water (683.4 ± 41.4 g/m2) was greater than in backwaters (430.9 ± 25.7 g/m2) and varied directly with differences in water depths in stands among years. Belowground standing crop of S. latifolia in open water (58.6 ± 4.3 g/0.25 m2) was also greater than in backwaters (40.9 ± 6.6 g/0.25 m2). During the growing season, approximately 46% of the belowground standing crop of this species was composed of tubers. Peak aboveground standing crop of S. rigida in open water (498.2 ± 35.5 g/m2) was greater than in backwaters (422.1 ± 26.3 g/m2), but a correlation with water depth was not found. Belowground standing crop of S. rigida in open water (39.3 ± 4.0 g/0.25 m2) was greater than in backwaters (25.6 ± 3.3 g/0.25 m2). Tubers constituted 61% of belowground standing crop of S. rigida, which was greater than the proportion for S. latifolia. Shallower water depth and finer particle size caused by siltation in backwater Sagittaria beds result in stands which are less productive.
Entomophthora erupta and Entomophthora helvetica sp. nov. (Zygomycetes: Entomophthorales), two pathogens of Miridae (Heteroptera) distinguished by pathobiological and nuclear features
Authors: Ben-Ze'ev I. S. , Keller S. , Ewen A. B.
Published: June 2010

An emended description of Entomophthora erupta and a description of Entomophthora helvetica sp. nov., fungi pathogenic to insects of the family Miridae, are given. Entomophthora erupta usually had 2–5 nuclei per conidium (mean diameter of 3.8 μm), colonized predominantly the abdomen of the host, and sporulated on the dorsal surface of the abdomen of the adult host, usually before death; E. helvetica usually had 8–13 nuclei per conidium (mean diameter of 1.6 μm), colonized the whole interior of the host, killed it in the nymphal stage before sporulation started, and sporulated on all parts of the cadaver. We advocate these features, including the pathobiological manifestations, as important taxonomic criteria at the infrageneric level of the genus Entomophthora sensu stricto.
Foliar nutrient dynamics, growth, and nutrient use efficiency of Hamamelis virginiana in three forest microsites
Authors: Boerner Ralph E. J.
Published: June 2010

To determine the relative importance of soil moisture and soil nutrient availability in determining levels of nutrient use efficiency, seasonal nutrient dynamics and growth rates were determined for individuals of Hamamelis virginiana L., an understory tree, in three forest microsites. The mixed oak site had the lowest levels of soil nutrients and moisture, the mixed mesophytic site the highest nutrient availability, and the valley bottom the highest moisture levels. Foliar nitrogen and phosphorus levels declined over the season in all trees, while calcium levels increased with time. Relative growth rates did not differ significantly among sites, though growth varied inversely with tree mass. Proportional nitrogen resorption was highest in trees at the fertile mesophytic site. Phosphorus and calcium use efficiency were higher at the infertile mixed oak site than the others, and phosphorus resorption was highest in trees from the mixed oak site. Projected nitrogen uptake needs for the next growing season were least at the mixed mesophytic site, while projected phosphorus uptake needs were least at the mixed oak site. Within the ranges of moisture and soil pH – nutrient availability present, growth and nitrogen dynamics seemed most closely correlated to soil moisture, and phosphorus dynamics to phosphorus availability. This differential dependence among elements on moisture levels is suggested to be the underlying reason for differences in the form of the relationship between proportional resorption and soil availability of N and P for a variety of woody species.
Relationship between seedling emergence and species frequency on a gradient of ground cover density in an abandoned pasture
Authors: Reader R. J.
Published: June 2010

Seedling emergence may be suppressed by dense ground cover causing species frequency to vary where ground cover ranges from moderate to dense. An experiment was conducted to determine how many community members showed matching patterns of variation in seedling emergence and frequency on a gradient of ground cover density in an abandoned pasture. Seedling emergence and species frequency were recorded on ridges, where ground cover was moderately dense, and in hollows, where ground cover was much denser. Eight of the 10 species examined showed ridge-hollow variation in seedling emergence and seven of the eight species showed a matching pattern of ridge-hollow variation in their frequency. When ground cover was removed experimentally, seedling emergence increased more in hollows than on ridges for all but one of the eight species. This suggests that ridge-hollow variation in seedling emergence resulted from greater suppression of seedling emergence by ground cover in hollows than on ridges. The close relationship between ridge-hollow variation in seedling emergence and species frequency in the community studied here indicates that models of spatial variation in community structure need to include spatial variation in seedling emergence as well as plant survival. Key words: ground cover, old field, seedling emergence.
Spatial pattern analysis of vegetative compatibility groups in the chestnut blight fungus, Cryphonectria parasitica
Authors: Milgroom Michael G. , MacDonald William L. , Double Mark L.
Published: June 2010

Vegetative compatibility groups were determined for 914 isolates of the chestnut blight fungus, Cryphonectria (Endothia) parasitica, collected over a 5-year period from American chestnut trees in eight regenerating clear-cut plots. We tested the hypothesis that the average distance between individuals in the same vegetative compatibility group is not different from the average distance between individuals with vegetative compatibility assigned at random. Nonrandom patterns were detected in all plots at least once during the study, indicating that vegetative compatibility groups were often aggregated. However, when multiple occurrences of vegetative compatibility groups on the same tree were eliminated from the analysis, there was only one test (out of 98 in total) in which the null hypothesis was rejected. We conclude that nonrandom patterns of vegetative compatibility groups are due primarily to multiple occurrences of vegetative compatibility groups on the same trees. Nearly half of all new cankers detected once the epidemic got started were in the same vegetative compatibility groups as cankers previously resident on the same tree. These data are consistent with the hypothesis that populations of C. parasitica are partly clonal in structure. Key words: Endothia parasitica, hypovirulence, Mantel test, matrix comparison, spatial autocorrelation.
Effects of prolonged light on germination of six lines of wild oat (Avena fatua)
Authors: Hou J. Q. , Simpson G. M.
Published: June 2010

Effects of prolonged light irradiation on seed germination of wild oat (Avena fatua L.) were studied in three nondormant and three dormant genetic lines. Light responses were observed in each of the lines tested. The expression of the light reaction is related to the genetic variability and dormancy states of the seeds. The light reaction can be observed in the dormant lines by removing the dormancy blocks in the seeds either through afterripening or by treatment with gibberellic acid or azide. Prolonged far-red, blue, and white light are inhibitory to germination. Prolonged red light had neutral, or inhibitory, effects compared with the corresponding dark germination. Germination responses to light depend on both the condition of phyto-chrome established by the light environment and the state of dormancy in wild oat seeds. Key words: phytochrome, dormancy, afterripening, genotype, gibberellin, azide.
Mechanisms producing plant zonation along a water depth gradient: a comparison with the exposure gradient
Authors: Shipley B. , Keddy P. A. , Lefkovitch L. P.
Published: June 2010

A 15-month field experiment was performed in the emergent zone of a freshwater riverine marsh along the Ottawa River, Canada, to determine whether the mechanisms producing plant zonation along the exposure gradient of freshwater shorelines also accounted for the zonal pattern along the water depth gradient. Three species (Carex crinita, Acorus calamus, and Typha angustifolia) were chosen, having contiguous distributions along a gradient of water depth. Ramets of each were planted within and beyond the field distributions of each, both in the presence and in the absence of the natural vegetation of each site. Although there was strong evidence of growth depression due to the presence of neighbouring plants (interference), there was no evidence of a differential response between species, between sites on the water depth gradient, or a combination of the two. As well, thee was no evidence that the water depth gradient represents a general gradient of decreasing productivity; rather, there was a qualitative change below the low-water level. These results are contrary to previously published results obtained along the exposure gradient of freshwater shorelines, where the effects of plant interference do vary both along the exposure gradient and among species. Key words: plant zonation, interference, water depth, exposure gradient.
Effects of partial removal of seed reserves on some aspects of seedling ecology of seven dune species
Authors: Zhang Jianhua , Maun M. A.
Published: June 2010

Greenhouse studies were conducted to determine the effects of partial removal of endosperm or cotyledons from seeds of seven dune species on seed germination, seedling emergence, seedling size, and dry matter allocation. Different proportions (0, 30, and 60%) were surgically removed from seeds of Agropyron psammophilum, Calamovilfa longifolia, Elymus canadensis, Leymus arenarius, Panicum virgatum, Lupinus perennis, and Strophostyles helvola. Partial removal of seed reserves caused a significant reduction in seedling variables 1 or 2 weeks after planting in sand. For example, seedling height, leaf area, dry weight of leaves, stem, and roots were significantly lower than control. The data suggest that the principal determinant of seedling size at an early stage was the amount of energy reserves in the endosperm or cotyledons of seeds. In addition to reduction in food reserves, partial removal of seed reserves caused some physiological damage to seedlings. In grass species, seedlings from surgically treated seeds devoted more dry matter to the roots and less to the leaves and stem than control seedlings. In dicot species, however, plants from treated seeds devoted more dry matter to the leaves and less to the roots. Key words: seed injury, seed germination, seedling size, energy allocation, dune plants.
Variability in temperature-dependent germination in eastern black nightshade (Solanum ptycanthum)
Authors: Hermanutz L. A. , Weaver S. E.
Published: June 2010

The colonization potential of the northwardly migrating weed Solanum ptycanthum was evaluated by comparing germination profiles of southern agrestal populations with northern marginal populations sampled from both ruderal and agrestal habitats. Under laboratory conditions, the seed from five maternal families from each population was subjected to six light:dark temperature regimes from 18:8 to 40:30 °C and germination rate (time to 50% germination) and final percent germination were monitored. The base temperature and thermal time (degree-days) required for 50% germination were calculated. Seeds from southern agrestal populations germinated over a broader temperature range than northern agrestal populations but had similar rates of germination, base temperatures, and thermal times. At the northern range limit, ruderal populations germinated faster and had smaller thermal times than agrestal populations but had similar base temperatures. Delayed emergence in agrestal habitats may be a response to cultural practices. Seeds from northern populations were heavier than southern populations. Plasticity of germination response to temperature did not differ between populations. The observed levels of genetic variability in all germination parameters suggest that future range expansion would be possible. Key words: temperature-dependent germination, agrestal, ruderal, marginal populations, genetic variability, plasticity.
Microfungi from Carpinus caroliniana
Authors: Bills Gerald F. , Polishook Jon D.
Published: June 2010

The microfungal flora and community structure of the bark of Carpinus caroliniana is described as perceived by a direct isolation method. Twenty-four bark discs were removed from 10 trees at five different sites in New Jersey and West Virginia and applied to three different isolation media. From 1200 bark discs from 50 trees, 155 species of fungi were isolated. The overall recovery rate was 11.5 species/tree. A medium with cycloheximide gave the highest species recovery rates and isolated the highest percentage of all the species recovered. A medium of malt–yeast extract gave the most isolates but lowest species recovery rate. Eleven of the 12 dominant species were preferentially isolated on one of the three isolation media. The community structure of the fungi recovered from Carpinus bark exhibited the typical dominance–diversity curve that has been reported for other saprobic fungal communities. Generally, the floristic composition was similar to the bark of other tree species previously studied in temperate deciduous forests. The total number of isolates was dominated by a few species of ubiquitous epiphytic taxa, but a large percentage of the species recovered appeared either at a single site or on a single tree. Sterile isolates accounted for 39% of the species and Coelomycetes for 13% of the species. The sites from West Virginia had a significantly higher recovery rate of species per tree than the New Jersey sites. In a search for fungi for potential biotechnological applications, bark is an easily utilized and rich resource. Simple isolation methods yield several ecological groups of fungi, including terrestrial epiphytes, soil decomposers, endophytes, entomopathogenic fungi, Ingoldian Hyphomycetes, and decomposer Basidomycetes. Key words: bark, ironwood, isolation methods, microbial diversity.
Accumulation of copper and nickel in plant tissues and an insect gall of lowbush blueberry, Vaccinium angustifolium, near an ore smelter at Sudbury, Ontario, Canada
Authors: Bagatto G. , Shorthouse J. D.
Published: June 2010

The accumulation of copper and nickel in plant tissues and galls of Hemadas nubilipennis on lowbush blueberry near an ore smelter at Sudbury, Ontario, was investigated. Concentrations of these metals in the root, stem, and leaf tissue decline logarithmically with increasing distance from the Sudbury smelter. The pattern of accumulation for copper and nickel in the various tissues was root > stem > leaf > berry; however, metal differences in these tissues were not as great in plants farther from the smelter. The root tissue is the primary site of accumulation of these metals when environmental levels of copper and nickel are high. The highest concentrations of copper and nickel were found in the galls, indicating that gall tissues act as a strong physiological sink for micronutrients and redirect nutrients from the host plant. Key words: Vaccinium angustifolium, copper, nickel, gall, Sudbury.
Phenotypic variation in Yukon populations of subalpine fir
Authors: Palmer C. Lynn , Parker William H.
Published: June 2010

To clarify the taxonomy of subalpine fir (Abies lasiocarpa (Hook.) Nutt.) and its relationship to balsam fir (Abies balsamea (L.) Mill.), populations from Washington to Yukon Territory and east to northern Ontario were compared on the basis of cone and needle morphology. Variation at the northern extreme of subalpine fir's range was expressed primarily within populations and appears to have arisen from selection owing to local environmental pressures. Multivariate analyses indicated geographic differentiation of coastal and interior subalpine fir populations and an affinity between northern and interior subalpine fir populations. Palynological data as well as similarities between northern and southern interior populations suggest a common Rocky Mountain refugium for the northern and interior populations. These results, together with earlier studies, justify varietal status for subalpine fir populations occurring east of the Coast and Cascade mountains of Washington and British Columbia and extending eastward to the Rocky Mountain crest. The new name for this interior variety is Abies lasiocarpa (Hook.) Nutt. var bifolia (Murray) Palmer & Parker. Balsam fir populations were indistinguishable from interior subalpine fir populations on the basis of needle morphology but well differentiated from these and coastal populations in cone morphology, supporting continued recognition of these firs as separate species. Key words: Abies balsamea, Abies lasiocarpa, Abies lasiocarpa var. bifolia, balsam fir, phenotypic variation, subalpine fir, taxonomy.
Formation and structure of root nodules induced on Macroptilium atropurpureum inoculated with various species of Rhizobium
Authors: Trinick Michael J. , Miller Celia , Hadobas Paul A.
Published: June 2010

Fifteen strains of Rhizobium leguminosarum biovar trifolii formed ineffective nodules and (or) nodule-like structures (rhizobia were re-isolated from both structures) on Macroptilium atropurpureum grown in enclosed glass tubes. Bacteria were observed among the parenchyma cells surrounding the nodule-like structures. One variant of R. leguminosarum biovar trifolii (NGR66/ST) isolated from M. atropurpureum formed nodules on this host that exhibited abnormal intercellular and intracellular infection. The bacteria (NGR66/ST) were contained within threadlike structures, surrounded by matrix material. The identities of the Rhizobium strains were confirmed serologically after reisolation and in sections of nodule tissue using immunogold labelling. Rhizobium leguminosarum biovar phaseoli strain NGR76 isolated from Phaseolus vulgaris formed nodules on M. atropurpureum resembling those formed by effective Bradyrhizobium strains. The association was partially effective in nitrogen fixation, and this was reflected in the nodule structure. The percentage of cells infected was lower than that in fully effective nodules. There was a high frequency of infected cells showing degeneration; these were located throughout the nodule tissue and were often adjacent to healthy infected cells. The rhizobia appeared to infect new nodule cells via infection threads, which were abundant both intercellularly and intracellularly in young, mature, and degenerating host nodule cells. Strains of R. leguminosarum biovar viceae and Rhizobium meliloti were unable to induce nodule-like structures on M. atropurpureum. Key words: Macroptilium, Bradyrhizobium, Rhizobium, microscopy, nodule, structure.
A preliminary micromorphological analysis of Eleocharis (Cyperaceae) achenes for systematic potential
Authors: Menapace Francis J.
Published: June 2010

Eleocharis R. Br. achenes were examined employing scanning electron microscopy to ascertain the systematic potential of the achene wall. It was found that the epidermis has useful microscopic characters to assist in the systematic assessment of Eleocharis. Acid-treated achenes, with their cuticle and outer periclinal cell walls removed, revealed micromorphological differences in epidermal features among the 26 taxa studied. Characters of taxonomic interest include the configuration of the anticlinal cell walls, the contour of the cell lumens, in addition to the presence or absence of lumen pits, lumen depressions, and silica bodies. Such characters may be of value in assessing the infrageneric ranks of Svenson. Preliminary results support the Aciculares, Chaetarieae, Leiocarpeae, Multicaules, Ovatae, Palustres, Sulcatae, and Truncatae as natural taxa. In contrast, current data suggest that the Pauciflorae, Ocreatae, Rigidae, and Tenuissimae are unnatural entities. Key words: Cyperaceae, Eleocharis, SEM, achene, micromorphology.