bluuebunny/crossref_metadata_2025 huggingface dataset:
Extensive Genetic Diversity in the
Plasmodium falciparum
Na
+
/H
+
Exchanger 1 Transporter Protein Implicated in Quinine Resistance
Authors: Vinayak Sumiti , Alam Mohammad Tauqeer , Upadhyay Mala , Das Manoj K. , Dev Vas , Singh Neeru , Dash Aditya P. , Sharma Yagya D.
Published: October 2007

The
Plasmodium falciparum
Na
+
/H
+
exchanger (
Pfnhe
-
1
) locus at chromosome 13 and another locus at chromosome 9 have recently been proposed to influence quinine resistance. Here, we sequenced the ms4760 locus of the
Pfnhe
-
1
gene from 244
P. falciparum
isolates collected from five different regions of India. A total of 16 different ms4760 alleles (with one to five DNNND repeats) were observed among these isolates. Interestingly, areas with a high prevalence of chloroquine and sulfadoxine-pyrimethamine resistance showed more
Pfnhe
-
1
DNNND repeats compared to low drug resistance areas. The extent of genetic diversity at the ms4760 locus also varied from one region to another, with expected heterozygosity values ranging from 0.47 to 0.88.
Antimicrobial Susceptibilities and Clinical Sources ofDialisterSpecies
Authors: Morio F. , Jean-Pierre H. , Dubreuil L. , Jumas-Bilak E. , Calvet L. , Mercier G. , Devine R. , Marchandin H.
Published: October 2007

Seventy-four strains representing the four species of the genusDialisterwere isolated from various clinical samples.Dialister pneumosintesandDialister micraerophiluswere the two mainly encountered species. Fifty-five isolates were tested against 14 antimicrobial agents. Decreased susceptibilities to piperacillin, metronidazole, macrolides, fluoroquinolones, and rifampin were demonstrated. The clinical impact of these decreased susceptibilities remains to be investigated but should prompt microbiologists to perform antimicrobial susceptibility testing for clinically importantDialisterspp.
Antimicrobial Action of Carbon Monoxide-Releasing Compounds
Authors: Nobre Lígia S. , Seixas João D. , Romão Carlos C. , Saraiva Lígia M.
Published: October 2007

Carbon monoxide (CO) is endogenously produced in the human body, mainly from the oxidation of heme catalyzed by heme oxygenase (HO) enzymes. The induction of HO and the consequent increase in CO production play important physiological roles in vasorelaxation and neurotransmission and in the immune system. The exogenous administration of CO gas and CO-releasing molecules (CO-RMs) has been shown to induce vascular effects and to alleviate hypoxia-reoxygenation injury of mammalian cells. In particular, due to its anti-inflammatory, antiapoptotic, and antiproliferative properties, CO inhibits ischemic-reperfusion injury and provides potent cytoprotective effects during organ and cell transplantation. In spite of these findings regarding the physiology and biology of mammals, nothing is known about the action of CO on bacteria. In the present work, we examined the effect of CO on bacterial cell proliferation. Cell growth experiments showed that CO caused the rapid death of the two pathogenic bacteria tested,
Escherichia coli
and
Staphylococcus aureus
, particularly when delivered through organometallic CO-RMs. Of importance is the observation that the effectiveness of the CO-RMs was greater in near-anaerobic environments, as many pathogens are anaerobic organisms and pathogen colonization occurs in environments with low oxygen concentrations. Our results constitute the first evidence that CO can be utilized as an antimicrobial agent. We anticipate our results to be the starting point for the development of novel types of therapeutic drugs designed to combat antibiotic-resistant pathogens, which are widespread and presently a major public health concern.
Characterization of the Antibody Response against
Plasmodium falciparum
Erythrocyte Membrane Protein 1 in Human Volunteers
Authors: Krause Darren R. , Gatton Michelle L. , Frankland Sarah , Eisen Damon P. , Good Michael F. , Tilley Leann , Cheng Qin
Published: October 2007

The immune response against the
Plasmodium falciparum
variant surface antigen
P. falciparum
erythrocyte membrane protein 1 (PfEMP1) is a key component of clinical immunity against falciparum malaria. In this study, we used sera from human volunteers who had been infected with the
P. falciparum
3D7 strain to investigate the development, specificity, and dynamics of anti-PfEMP1 antibodies measured against six different strain 3D7 Duffy binding-like domain 1α (DBL1α) fusion proteins. We observed that a parasitemia of 20 to 200 infected erythrocytes per μl was required to trigger an antibody response to DBL1α and that antibodies against one DBL1α variant cross-react with other DBL1α variants. Both serum and purified immunoglobulin Gs (IgGs) were able to agglutinate infected erythrocytes, and purified anti-DBL1α IgGs bound to the live infected red blood cell surface in a punctate surface pattern, confirming that the IgGs recognize native PfEMP1. Analysis of sera from tourists naturally infected with
P. falciparum
suggests that the anti-PfEMP1 antibodies often persisted for more than 100 days after a single infection. These results help to further our understanding of the development of acquired immunity to
P. falciparum
infections.
High-Affinity Zn2+Uptake System ZnuABC Is Required for Bacterial Zinc Homeostasis in Intracellular Environments and Contributes to the Virulence ofSalmonella enterica
Authors: Ammendola Serena , Pasquali Paolo , Pistoia Claudia , Petrucci Paola , Petrarca Patrizia , Rotilio Giuseppe , Battistoni Andrea
Published: October 2007

To investigate the relevance of zinc in host-pathogen interactions, we have constructedSalmonella entericamutant strains in which theznuAgene, which encodes the periplasmic component of the ZnuABC high-affinity Zn2+transporter, was deleted. This mutation does not alter the ability ofSalmonellato grow in rich media but drastically reduces its ability to multiply in media deprived of zinc. In agreement with this phenotype, ZnuA accumulates only in bacteria cultivated in environments poor in zinc. In spite of the nearly millimolar intracellular concentration of zinc, we have found thatznuAis highly expressed in intracellular salmonellae recovered either from cultivated cells or from the spleens of infected mice. We have also observed thatznuAmutants are impaired in their ability to grow in Caco-2 epithelial cells and that bacteria starved for zinc display decreased ability to multiply in phagocytes. A dramatic reduction in the pathogenicity of theznuAmutants was observed inSalmonella-susceptible (BALB/c) orSalmonella-resistant (DBA-2) mice infected intraperitoneally or orally. This study shows that the amount of free metals available for bacterial growth within the infected animal is limited, despite the apparent elevated concentration of free metals within cells and in plasma and suggests thatSalmonellaexploits the ZnuABC zinc transporter to maximize zinc availability in such conditions. These results shed new light on the complex functions of zinc in vertebrate and bacterial physiology and pave the way for a better comprehension of pathogenic mechanisms inSalmonellainfections.
Individual Matrix Metalloproteinases Control Distinct Transcriptional Responses in Airway Epithelial Cells Infected with
Pseudomonas aeruginosa
Authors: Kassim Sean Y. , Gharib Sina A. , Mecham Brigham H. , Birkland Timothy P. , Parks William C. , McGuire John K.
Published: October 2007

Airway epithelium is the initial point of host-pathogen interaction in
Pseudomonas aeruginosa
infection, an important pathogen in cystic fibrosis and nosocomial pneumonia. We used global gene expression analysis to determine airway epithelial transcriptional responses dependent on matrilysin (matrix metalloproteinase 7 [MMP-7]) and stromelysin-2 (MMP-10), two MMPs induced by acute
P. aeruginosa
pulmonary infection. Extraction of differential gene expression (EDGE) analysis of gene expression changes in
P. aeruginosa
-infected organotypic tracheal epithelial cell cultures from wild-type,
Mmp7
−/−
, and
Mmp10
−/−
mice identified 2,091 matrilysin-dependent and 1,628 stromelysin-2-dependent genes that were differentially expressed. Key node network analysis showed that these MMPs controlled distinct gene expression programs involved in proliferation, cell death, immune responses, and signal transduction, among other host defense processes. Our results demonstrate discrete roles for these MMPs in regulating epithelial responses to
Pseudomonas
infection and show that a global genomics strategy can be used to assess MMP function.
Fusion Proteins Containing Family 1 and Family 2 PspA Fragments Elicit Protection against
Streptococcus pneumoniae
That Correlates with Antibody-Mediated Enhancement of Complement Deposition
Authors: Darrieux M. , Miyaji E. N. , Ferreira D. M. , Lopes L. M. , Lopes A. P. Y. , Ren B. , Briles D. E. , Hollingshead S. K. , Leite L. C. C.
Published: October 2007

PspA is an important pneumococcal vaccine candidate that is capable of inducing protection in different animal models. Because of its structural diversity, a PspA-based vaccine should contain at least one fragment from each of the two major families (1 and 2) in order to elicit broader protection. In the present work, we have tested the potential of PspA hybrids containing fused portions of family 1 and 2 (PspA1ABC-4B and PspA1ABC-3AB) PspA fragments to induce protection against pneumococci bearing distinct PspA fragments. Sera from mice immunized with these hybrid PspA fragments were able to increase C3 deposition on pneumococci bearing PspA fragments from both families, in contrast with sera made against the PspA family 1 (PspA1ABC) and PspA family 2 (PspA3ABC) fragments, which were effective only within the same family. Although PspA hybrids were able to extend protection against pneumococcal infection with strains bearing diverse PspA fragments, the immunity elicited by family 2 was clade dependent, suggesting that PspA fragments from family 2 clades 3 and 4 should both be included in a comprehensive PspA vaccine. These results indicate that PspA fusion proteins constitute an efficient immunization strategy for future PspA-based antipneumococcal vaccines since they are able to extend protection provided by a protein derived from a single transcript.
Treponema denticola
Activates Mitogen-Activated Protein Kinase Signal Pathways through Toll-Like Receptor 2
Authors: Ruby John , Rehani Kunal , Martin Michael
Published: October 2007

Treponema denticola
, a spirochete indigenous to the oral cavity, is associated with host inflammatory responses to anaerobic polymicrobial infections of the root canal, periodontium, and alveolar bone. However, the cellular mechanisms responsible for the recognition of
T. denticola
by the innate immune system and the underlying cell signaling pathways that regulate the inflammatory response to
T. denticola
are currently unresolved. In this study, we demonstrate that
T. denticola
induces innate immune responses via the utilization of Toll-like receptor 2 (TLR2) but not TLR4. Assessment of TLR2/1 and TLR2/6 heterodimers revealed that
T. denticola
predominantly utilizes TLR2/6 for the induction of cellular responses. Analysis of the mitogen-activated protein kinase (MAPK) signaling pathway in
T. denticola
-stimulated monocytes identified a prolonged up-regulation of the MAPK extracellular signal-related kinase 1/2 (ERK1/2) and p38, while no discernible increase in phospho-c-Jun N-terminal kinase 1/2 (JNK1/2) levels was observed. With the aid of pharmacological inhibitors selectively targeting ERK1/2 via the mitogen-activated protein kinase/extracellular signal-related kinase 1/2 kinase and p38, we further demonstrate that ERK1/2 and p38 play a major role in
T. denticola
-mediated pro- and anti-inflammatory cytokine production.
Studies of the rooting of cuttings of Hydrangea macrophylla: DNA and protein changes
Authors: Molnar J. M. , LaCroix L. J.
Published: October 2007

The anatomy of root initiation of Hydrangea macrophylla and associated changes in protein and DNA synthesis during adventitious root formation are described. Observations showed that adventitious roots originated from preformed root initials in the phloem ray parenchyma cells. The roots appeared 10 to 12 days after the cuttings were made.The total protein content of the root initials increased over 100% in the first 4 days, while there was no rapid increase in DNA content of the cells until the sixth day. The estimated mean content of total protein per cell stabilized on or before the sixth day from the time the cuttings were made, and thenceforth appeared to come into equilibrium with the rate of cell division.
A theory of translocation in phloem of Heracleum by contractile protein microfibrillar material
Authors: Fensom D. S.
Published: October 2007

Recent findings based on light microscopy, electron microscopy, electrical gradients, microinjection, and tracer feeding, all on isolated but living phloem strands of Heracleum are here summarized and collated. A new theory of translocation is presented in which sucrose transport occurs in two chief modes. The first is based on microperistaltic movement of contractile lipoprotein which is thought to extend axially through the sieve tube. The second is a mass flow of solution around the contractile microfibrillar material, but chiefly activated by it. The microfibrillar material transports sucrose in pulses at about 400 cm h−1 and this mode of translocation is stopped by cold blocks and desiccation, but not by callose. The mass flow mode is slower and is stopped by callose formation and also by the cessation of activity of the microfibrillar or pulsing mode. A third small surface-layer component of translocation is also indicated, operating at speeds above 1000 cm h−1.
A continuous flow system for inducing and observing asexual spore formation in Aphanomyces euteiches
Authors: Hoch H. C. , Mitchell J. E.
Published: October 2007

A technique is described that permits light microscopic observation of living hyphae in a liquid medium for an extended period of time. The procedure described was used to study cytological changes in hyphae of Aphanomyces euteiches during the transition from the vegetative state through the delineation of asexual spores and their extrusion from the sporangium apex.
Growth kinetics of Marquis wheat. VII. Dependence on photoperiod and light compensation point in vegetative phase
Authors: Macdowall F. D. H.
Published: October 2007

The maximum rate coefficients for the vegetative phase of growth in dry weight of shoots and roots were independent of the photoperiod in plants grown at six different light intensities of 12- or24-h duration at 20 °C. The strict dependence of plant growth on only the total daily incident radiant energy was proved by the superposition of hyperbolic plots of growth coefficients obtained for five different photoperiods and for the different light intensities. Root growth was very sensitive to photoperiod at moderate light intensity. Growth kinetics changed from first to zero order in plant dry weight at a 12-h photoperiod with a light intensity of 150 ft-c (3750 ergs cm−2 s−1) depending on pretreatment. The light compensation point of plant growth occurred at16 × 107 ergs cm−2 day−1; that for shoots was lower, and that for roots was higher.
The fine structure of conidiogenesis in Alysidium resinae (=Torula ramosa)
Authors: Ellis D. H. , Griffiths D. A.
Published: October 2007

Conidia of Alysidium resinae (Fr.) M. B. Ellis (=Torula ramosa Peck) arise enteroblastically from polyblastic, ampulliform conidiogenous cells after mechanical rupture of the conidiogenous cell wall and are produced in either branched or unbranched acropetalous chains, successively younger conidia being produced enteroblastically from the immediately older conidia. There is no indication that conidial evagination occurs via enzymatically produced channels in the parent wall, protrusion being exclusively mechanical. Attention is drawn to the controversy surrounding the enteroblastic tretic mode of conidiogenesis.
Systematics of Conidiobolus (Entomophthorales) using numerical taxonomy. III. Descriptions of recognized species
Authors: King Douglas S.
Published: October 2007

The descriptions of 26 of the 27 recognized species are emended in accordance with previously reported morphological, nutritional, and numerical taxonomic work.
An unusual osmundaceous specimen from Antarctica
Authors: Schopf James M.
Published: October 2007

An Antarctic specimen chiefily consisting of the osmundine root mat and including branched stems of a fern, assignable to a new species Osmundacaulis beardmorensis, is described and illustrated. Delicate tissues are generally not preserved and no separate petioles can be recognized. Nevertheless, the Early Triassic age of this specimen is well established and the features that can be described seem to fit generally into an intermediate position between Osmundacaulis herstii of the Argentine Late Triassic and Palaeosmunda of the Late Permian from Australia. Secretory islands in petiolar areas seem to be distinctive. The species further illustrates the long established cosmopolitan distribution of members of the Osmundaceae.
Sirococcus blight: a seed-borne disease of container-grown spruce seedlings in Coastal British Columbia forest nurseries
Authors: Sutherland Jack R. , Lock W. , Farris S. H.
Published: October 2007

Sirococcus blight, caused by Sirococcus strobilinus Preuss, was shown to be a seed-borne disease of container-grown Picea sitchensis (Bong.) Carr., P. glauca (Moench) Voss, P. engelmannii Parry, and P. glauca × P. engelmannii spruces. The fungus was best detected by germinating seeds from seedlots with consistent disease histories, in autoclaved soil mix in pots (kept at 16 to 20 °C, and at light intensities of 900 to 1800 lx), and isolating the pathogen from diseased seedlings. Seed-borne isolates of S. strobilinus were pathogenic to P. sitchensis seedlings. The pathogen was present on 0.3 to 3.1% of the seeds of infested seedlots. Seeds with shrunken contents yielded the pathogen seven to nine times more often than seeds with normal-appearing contents. Disease incidence was unrelated to seedcoat damage or prevalence of empty seeds. Histological examinations revealed presence of the pathogen throughout the endosperm and embryo tissues of diseased seeds. The results are discussed in relation to incidence of Sirococcus blight in Coastal, container nurseries.
Réactivation du bourgeon cotylédonnaire du Pois en réponse à la kinétine
Authors: Nougarède Arlette , Rembur Jacques , Rondet Pierre
Published: October 2007

For three components (apical meristem, subapical internodes, and foliar apparatus) of Pisum sativum (cv. nain hâtif d'Annonay) cotyledonary buds, DNA microdensitometry, mitotic indices, and release of growth have been used to detect changes produced by kinetin applications (50 μg/mL). One kinetin treatment is sufficient to release the cell cycle, but continuous kinetin supply is necessary to maintain bud elongation. At the apical, subapical, and foliar levels, inhibited cotyledonary buds contain a majority of nuclei with 2C DNA content, in the G1 phase of the cell cycle. Following hormonal treatment, the prereplicative phase of the noncycling cells is at least 6 h in the whole bud. The lag period for the release of bud growth is between 15 and 23 h in subapical regions (first and second internodes) and between 23 and 38 h at the foliar level. At subapical and foliar levels, a few mitoses precede and then follow the elongation process. The first mitoses are from G2 nuclei of the inhibited bud. The following ones, more numerous, are from noncycling cells of inhibited buds, which have entered the S phase in response to kinetin application. The degree of inhibition of an axillary bud, estimated by the distribution of the DNA content in its three components, conditions the events induced by hormonal treatment or decapitation. The discussion shows how the knowledge of the original nuclear states of inhibited buds is necessary to understand axillary bud reactivation.
Histochemical characteristics of Glomus etunicatus infection of Citrus limon fibrous roots
Authors: Nemec S.
Published: October 2007

Lipid in vesicles and hyphae reacted positively to a variety of reagents that have an affinity for neutral lipids. In contrast, arbuscules did not appear to contain neutral lipid, but did react positively to phosphoglyceride tests and glycolipid. Walls of vesicles and hyphae contained chitin, but arbuscule walls appeared to contain mainly glycolipid. Young arbuscules, hyphae, and immature vesicles were rich in basic protein. Phenolics were detected in vesicle walls and hyphal attachments, but none accumulated around infected areas even though laccase activity was present in cortical regions occupied by young arbuscules. Dehydrogenases were present in young arbuscules, hyphae, and in immature vesicles still containing noticeable amounts of cytoplasm. Peroxidase and catalase activity in senescing arbuscules were probably associated with fatty acid oxidation in the fungus.
Sporulation in Alternaria cichorii is controlled by a blue and near ultraviolet reversible photoreaction
Authors: Vakalounakis Demetrios J. , Christias Christos
Published: October 2007

Sporulation in Alternaria cichorii Nattrass was induced by near ultraviolet irradiation (< 340 nm) and inhibited by blue light. The inhibitory action of blue light could be reversed by near ultraviolet irradiation. Induction by near ultraviolet could be annulled by subsequent exposure to blue light. Sporulation during a sequential exposure to blue–near ultraviolet light was always determined by the quality of the last irradiation applied. A series of alternating doses of blue–near ultraviolet light ending in near ultraviolet promoted sporulation whereas a series ending in blue light inhibited sporulation. This is considered strong evidence for the existence of an interconvertible pigment system absorbing at the blue and near ultraviolet regions of the spectrum which controls sporulation in A. cichorii.
The stipules of Comptonia peregrina
Authors: Macdonald Alastair D.
Published: October 2007

This report examines the serial changes in stipule expression in Comptonia peregrina (L.) Coult. for the various categories of appendages on a branch, namely, prophylls, remaining bud scales, foliage leaves, and the distal cluster of scalelike leaves. Stipules are not associated with the two prophylls and they are not evident on the remaining two bud scales at maturity. Stipules are intiated on the leaf base of these two bud scales and are raised up on the free leaf base, which constitutes the protective scale. Approximately 18 stipulate foliage leaves form. Their stipules arise on the leaf base and assume a cauline position at maturity. The foliage leaf has no free leaf base. Numerous lanceolate leaves with basally connate, lanceolate stipules, scale leaves with stipule lobes, and scale leaves without stipule lobes form sequentially on the distal portion of the branch which eventually aborts and abscises. Most of the scale leaf is free leaf base. Correlations may be drawn between distal scale leaf and bud scale development, i.e., proportion of free leaf base to upper leaf zone, lack of intemode expansion, and small dimensions of the shoot apex at the time of inception of these structures. Prophylls are considered to be unique structures because of their position, precocious inception, leaf base – stem relationship, lack of stipules, and single vascular bundles. The phytogeny of stipules is unknown but in view of the proposed origin of the megaphyllous leaf the question is asked whether stipules may be considered homologous to prophylls.
Inhibition of photosynthesis by low oxygen concentrations
Authors: McVetty P. B. E. , Canvin D. T.
Published: October 2007

The effect of changing the oxygen concentration from 21 to 2% on photosynthesis of wheat, sunflower, and soybean was investigated. At low CO2 concentrations and low light intensities, a stimulation of photosynthesis was observed in 2% oxygen compared with the rate in 21% O2. At high CO2 concentrations and high light intensities, a temporary inhibition of photosynthesis was observed when the oxygen concentration was changed from 21 to 2%. In wheat and sunflower, this inhibition was observed at progressively lower CO2 concentrations as temperatures were decreased. In soybean only, a slight inhibition of photosynthesis was observed at higher temperatures. In some cases, especially in plants grown under a low light intensity, a long-lasting (> 45 min) inhibition of photosynthesis was observed. In most cases, however, the inhibition lasted only for several minutes and final rates of photosynthesis in 2% O2 were equal to or greater than the rate of photosynthesis in 21% O2. The stimulatory effect of oxygen on photosynthesis at high CO2 concentrations and high light intensities could possibly be due to a regulation of the oxidation–reduction state of the electron transport chain and the maintenance of phosphorylation.
Vascularisation de la fleur pistillée de Begonia handelii
Authors: Barabé Denis
Published: October 2007

The pistillate flower of Begonia handelii Irmscher has a tetramerous gynoecium. The analysis of serial sections shows that the anatomical pattern observed by Gauthier (1950) on trimerous gynoecia also occurs in tetramerous gynoecia. For each carpel there are theoretically seven vascular bundles which leave the stele. The vascular pattern of the pistillate flower of B. handelii leads us to adopt the appendicular theory of the inferior ovary. The position of vascular bundles, the presence of gaps, and the absence of recurrent bundles show that the ovary is formed by the union of appendicular organs. In this case, the inferior ovary results from the close union of carpels and perianth parts. In the pistillate flower of B. handelii, the perianth parts are disposed on two dimerous whorls: the first corresponds to a whorl of sepals, and the second to a whorl of petals.
Variation in isoabienol content in Pinus sylvestris needles
Authors: Gref Rolf
Published: October 2007

The diterpene alcohol isoabienol occurs in some individual pine (Pinus sylvestris L.) trees, in which it constitutes 0.6–1.0% of the needle dry weight, and is totally lacking in others. Isoabienol can be found only in the needles, mainly in fully outgrown needles, not in shoot axis tissue, wood, or cortex oleoresin. If sampling is limited to mature needles, within-tree, within-clone, and seasonal variations are insignificant, making isoabienol a suitable marker substance for studies of chemotaxonomy and population genetics. Isoabienol occurs more frequently in northerly provenances than in southerly. No correlation could be shown between isoabienol occurrence and the monoterpene or resin acid composition of the needles. There was no family-level correlation between isoabienol occurrence and resistance towards the pathogenic fungus Gremmeniella abietina.
Vegetation and nutrient status of northern Michigan bogs and conifer swamps with a comparison to fens
Authors: Schwintzer Christa R.
Published: October 2007

The vegetation and shallow groundwater were sampled at six bog and four conifer swamp sites in northern Lower Michigan in the same manner as at five previously described fen sites.The bogs were characterized by well-developed field (low shrub, herb, and fern), and bryophyte layers and strongly acid waters (pH 3.8–4.3). The most prevalent field-layer plants were Chamaedaphne calyculata and Carex oligosperma while Sphagnum spp. dominated the bryophyte layer. The number of vascular plant species in the field layer was 14 ± 4 (mean ± SD). The conifer swamps were characterized by well-developed tree and field layers and circumneutral waters (pH 7.0–7.4). Thuja occidentalis strongly dominated the tree layer and Mitella nuda, Abies balsamea, and Maianthemum canadense were the most prevalent field layer plants. The number of vascular plant species in the field layer was 57 ± 7 (mean ± SD).The bogs, conifer swamps, and fens are related developmentally (successionally) but differ strongly in floristics, species density, proportion of evergreen species, role of symbiotic nitrogen fixing species, role of Sphagnum spp., and water chemistry. Although these wetland types are often grouped together under the term "bog" or are considered successional stages of "bog," they differ markedly in vegetation and water chemistry, and are best considered as separate but related wetland types.
Seasonal changes in water-soluble carbohydrates of Populus tremuloides leaves
Authors: Wildman H. G. , Parkinson D.
Published: October 2007

Leaf leaching was simulated by washing leaves in distilled water. A variation in the quality and quantity of aspen poplar leaf leachate carbohydrates with respect to season and height in the tree canopy was observed. Some carbohydrates were subject to less variation than others. Fructose was the major component of the leachate carbohydrate at all sampling times. Other carbohydrates occurring in the leachate included glucose, galactose, inositol, sucrose, maltose, raffinose, an unknown 12-C, and an unknown 18-C carbohydrate. The possibility that restricted availability of total and (or) particular carbohydrates may play a role in controlling microbial development on leaf surfaces is discussed.
Growth and morphology of submersed freshwater macrophytes in relation to light and temperature
Authors: Barko J. W. , Hardin D. G. , Matthews M. S.
Published: October 2007

Variations in the growth and morphology of three North American freshwater macrophyte species, Elodea canadensis Michx., Potamogeton nodosus Poiret (P. americanus), and Vallisneria americana Michx., were investigated in large white fiberglass tanks over broad experimental ranges of greenhouse light (ca. 100–1500 μE∙m2∙s−1 as midday maximum photosynthetically active radiation (PAR)) and temperature (12–32 °C). Response variables considered in the study included biomass production, shoot density, shoot length, and various characteristics of leaf form.Total biomass production in all species generally increased with both increasing light and increasing temperature (to at least 28 °C). However, variations in biomass and other parameters as well were highly influenced by the interactive relationship between light and temperature. Shoot density correlated directly with biomass production in these species under all experimental conditions. In contrast, light and temperature elicited opposing responses in shoot length, which decreased with increasing light but increased with increasing temperature. The extent of variations in leaf morphology differed among species, apparently reflecting intrinsic differences in heterophyllous capabilities.Light and temperature appear to interact in influencing lower limits of macrophyte depth distribution and related variations in the duration of seasonal growth. Temperature is likely to assert a strong influence on the latitudinal distribution of submersed freshwater macrophytes, dependent upon species-specific differences in response to temperature and basic differences in macrophyte life cycle.
Diesel oil spill in a subalpine meadow: 9 years of recovery
Authors: Belsky Joy
Published: October 2007

Two subalpine meadow communities near Mt. Baker, Washington, were inundated by a spill of 26 000 L of diesel oil in 1972. Studies were made of the initial impact of the oil on the vegetation and of community recovery over 9 years. Within two growing seasons following the spill, plant cover had decreased from a prespill cover of nearly 100% to 1% and all species except Phyllodoce empetriformis, Carex lenticularis, and Rhacomitrium sudeticum had died. Seedlings of Carex nigricans began to appear on bare soil after 1 year, followed by seedlings of other common subalpine species 2 to 4 years later. Nine years after the perturbation 5 to 20% of the ground was covered with vegetation and the original disturbance could no longer be discerned by a casual observer.
Studies on Indian polypores. V. Morphological and cultural characters of Trametes cubensis
Authors: Roy Anjali
Published: October 2007

Morphological and cultural characters of Trametes cubensis (Mont.) Sacc. have been studied and in the light of these findings the taxonomy of the fungus is discussed. The new combination Daedalea cubensis (Mont.) Roy is proposed.
In situ H2 production and utilization by natural populations of N2-fixing blue-green algae
Authors: Paerl Hans W.
Published: October 2007

Contemporaneous in situ acetylene-reduction, 15N2-fixation, and 3H2-exchange assays reveal parallel patterns of N2 fixation and H2 utilization in natural populations of the blue-green algae Anabaena and Aphanizomenon. As spring and summer blooms progress, increasing ratios of acetylene reduction versus 15N2 fixation closely follow elevated rates of cellular H2 utilization. Both acetylene-reduction and H2-utilization rates were largely attributable to blue-green algae as opposed to associated bacteria and other phytoplankton. It is concluded that elevated H2 utilization reflects increased H2 production via nitrogenase. This can be substantiated by monitoring rising acetylene-reduction versus 15N2-fixation ratios during bloom development. Simultaneous deployment of the above techniques provides evidence for (a) in situ H2 production and (b) seasonal trends in rates of H2 production among natural blue-green algal populations.
Genetics of Gracilaria tikvahiae (Rhodophyceae). VIII. Phenotypic and genetic characterization of some selected morphological mutants
Authors: Patwary Mohsin U. , Meer John P. van der
Published: October 2007

Morphological mutants of the marine red alga Gracilaria tikvahiae have been isolated in an initial attempt to develop improved strains for mariculture by selection of plants with altered growth habits. Both spontaneous and ethylmethanesulphonate-induced mutants were collected for this study. The phenotypes of the mutants range from plants with extremely fine, highly branched fronds to plants with thick puffy fronds. Among 10 mutants selected for more detailed study, 9 have distinctly different phenotypes. Genetic results identify nine mutant cistrons corresponding to the nine phenotypes. All the phenotypes are transmitted as single, mostly recessive, Mendelian mutations, with possible linkage appearing in two combinations of mutants. Growth trials in culture indicate that at least some of the mutants grow better than a genetically related wild type. In general, plants with increased branching showed the greatest promise.
Adaptation in widespread populations of Rumex crispus as determined using composite diagrams
Authors: Hume L. , Cavers P. B.
Published: October 2007

Eleven genetically different populations of Rumex crispus L., 10 from eastern North America and 1 from Bangor, Wales, were sampled. Offspring from these populations were grown under cultivation in a uniform garden at London, Ontario. Determinations of 47 morphological characters were made. Twenty-two environmental variables relating to temperature, daylight, moisture, soil nutrients, particle size, and pH were obtained or determined. A new technique, the use of composite drawings of R. crispus plants, utilized results from regression analyses performed between plant and environmental characters. Plants from cold climates tended to be short and compact with large numbers of stomata per unit area, an adaptation likely to reduce heat loss and optimize CO2 exchange. Plants originating on coarse-textured soil were small and spreading relative to those from soil with larger amounts of silt and clay. Highly overlapping, appressed branches and relatively small stomata were characteristic of plants from dry localities. The importance of examining large numbers of characters in studies of geographic variation is demonstrated and discussed. Composite drawings are shown to be useful in summarizing such large volumes of data.
Rôle des différents territoires foliaires dans le phénomène de la tubérisation chez la patate douce
Authors: Sihachakr Darasinh , Rossignol Line , Rossignol Martial , Nozeran René
Published: October 2007

Sweet potato (Ipomoea batatas (L.) Lam., Convolvulaceae) leaf cuttings initiate several kinds of roots, some of which develop tubers. The influence of different parts of the lamina on the root tuberization rate was tested by means of excision and incision of lamina pieces. Following the ablation, it has been shown that: (i) retention of half of the whole symmetrical structure of the lamina is necessary for optimal root tuberization, equivalent to that of the intact leaf; (ii) below this limit, root tuberization rate depends on the size of the assimilating surface of the leaf; (iii) when the median veins are affected there is a significant decrease of tuberization rate compared with an equivalent lamina excision which does not affect these veins. We conclude therefore that these median veins may have a particular role in the metabolite translocation which controls, to a large extent, the root tuberization process.
Growth and reproduction of American ginseng (Panax quinquefolius) in Wisconsin, U.S.A.
Authors: Carpenter Susan G. , Cottam Grant
Published: October 2007

The phenology and development of southern Wisconsin populations of wild ginseng (Panax quinquefolius L.) are described. In natural forests, ginseng plants grow slowly, and most plants do not reach reproductive maturity until they are at least 8 years old. Ginseng flowers are perfect, but maturity of male and female reproductive parts is separated temporally in each flower. Ginseng individuals are not obligate outcrossers, and the flowers are visited by generalist pollinators. Exclusion of pollinators did not reduce fruit or seed set. Aging techniques usually underestimate age. Number of leaves (plant stage) is a more appropriate indicator of development than is the number of "annual" stem scars on the rhizome. The number of seeds produced by a plant may be predicted from the number of leaves and the leaf area of the largest leaflet. Accurate estimates of the number of ginseng plants in an area can be made by sampling early in the summer. However, projections of survival and reproductive success in a ginseng population must account for mortality and for plants that senesce early in the summer months before producing seeds. We recommend that ginseng harvesting in Wisconsin be allowed only after September 1 to insure that fruits on mature plants are ripe.
Light-induced alteration of leaf sterol content and late blight disease development in tomato
Authors: Bradford B. , Moore L. D. , Orcutt D. M.
Published: October 2007

‘Nova’ and 'Beefsteak,' cultivars of tomato (Lycopersicon esculentum Mill.), were grown in chambers under light intensities of 240 or 120 μE∙m−2∙s−1. Thirty-five days after seeding, half of the tomato plants were harvested for sterol analysis and the others were inoculated with a tomato race O isolate of Phytophthora infestons (Mont.) de By. Late blight symptoms were assessed 10 days after inoculation from the number of leaves showing disease (disease incidence) and the amount of blighted area of each leaf (percent colonization). Disease incidence and percent colonization were not influenced by light intensity with 'Nova' plants, but 'Beefsteak' plants grown under low light were significantly [Formula: see text] more diseased than those exposed to the higher light intensity. Changes in free sterol, steryl ester, and total sterol concentrations between plants grown under different light intensities were similar for both cultivars. A significant decrease in the steryl glycoside concentration of low light grown 'Beefsteak' plants correlated with increased disease incidence. The possible role of steryl glycosides and their derivatives in late blight disease development is discussed.
Surface structural analysis of cultured cotyledons of Douglas-fir
Authors: Kirby Edward G. , Schalk Margaretha E.
Published: October 2007

Cotyledons of Douglas-fir are triangular in cross section and possess two epistomatic surfaces with centrally located stomatal rows (commonly seven). After 1 week in culture on a medium inducing adventitious shoot formation (5 μM N6-benzylaminopurine and 5 μM α-naphthalene acetic acid (NAA)) or callus proliferation (5 μM NAA) cells of the hypodermal region immediately below the epidermis begin to elongate and divide rupturing the epidermis. Apical domes of adventitiously produced bud primordia emerge from the ruptured epidermis after 14–21 days in culture on shoot induction medium. Emergence of buds takes place preferentially on epistomatic cotyledonary surfaces. The large number of hypodermal cells that respond to shoot induction medium by forming adventitious shoots suggests further investigation of fundamental events associated with morphogenesis in cotyledon cultures of Douglas-fir.
Studies of vegetative compatibility–incompatibility in higher plants. V. A morphometric analysis of the development of a compatible and an incompatible graft
Authors: Moore Randy
Published: October 2007

A morphometric analysis of graft development in (i) the compatible autograft in Sedum telephoides, and (ii) the incompatible heterograft between Sedum telephoides and Solanum pennellii was performed to characterize ultrastructural responses of grafting cells in compatible and incompatible unions. In the compatible autograft, relative volume of hyaloplasm (in the protoplasm) increases 750% by 3 days after grafting. This increase in hyaloplasmic volume is accompanied by a 61% decrease in relative volume of the vacuome during the same period. Relative volume of dictyosomes (in the protoplasm) increases fourfold during the first 8 h after grafting. Relative volumes of mitochondria, endoplasmic reticulum, nuclei, and nucleoli increase less dramatically during early stages of graft development. The time required to reestablish control (i.e., 0 h) volumes for these organelles is quite variable, ranging from 7 days for dictyosomes to 28 days for the vacuole and hyaloplasm. These results indicate that the intensity and duration of the responses of cellular components to the wound recovery associated with a compatible graft union are organelle specific. In the incompatible heterograft, the responses of all cellular organelles (except nuclei and components of the endomembrane system) are similar to that of the compatible autograft through the first 24 h after grafting. By 3 days after grafting, however, nuclei and components of the endomembrane system exhibit significantly lower relative volumes in the incompatible heterograft than in the compatible autograft. Therefore, nuclei and components of the endomembrane system are the first cellular components to exhibit signs of cellular incompatibility during graft formation in the incompatible heterograft between Sedum and Solanum.
The anatomy of the leaf of red pine, Pinus resinosa. II. Vascular tissues
Authors: Gambles R. L. , Dengler R. E.
Published: October 2007

The anatomy and ultrastructure of the endodermis and enclosed vascular tissues of the midregion of the mature secondary needle-leaf of Pinus resinosa are described. Within the uniseriate endodermis are two vascular traces surrounded by transfusion tissue. The endodermal cells have differentially thickened walls which lack Casparian strips but are lignified. Plasmodesmata traversing pit regions form a symplastic interconnection between mesophyll, endodermal, and transfusion parenchyma cells. In the lateral bundle region plasmodesmata extend this symplastic pathway across the cell walls of subjacent transfusion parenchyma and richly protoplasmic albuminous cells to the metaphloem. Four distinct types of transfusion tracheids have been defined on the basis of cell shape and location. Transfusion tracheids in the lateral bundle regions form direct radial connections between metaxylem and endodermis.
Sea ice diatoms from Manitounuk Sound, southeastern Hudson Bay (Quebec, Canada). : II. Naviculaceae, genus Navicula
Authors: Poulin Michel , Cardinal André
Published: October 2007

The genus Navicula is the major constituent of the sea ice diatom community of Manitounuk Sound, Hudson Bay. Taxonomical information is given for 43 taxa of the genus Navicula by means of complete illustrated descriptions. One new species and six varieties are described and a new combination is proposed.
Modification du pH vacuolaire des cellules épidermiques foliaires de Solanum dulcamara soumises à l'action d'un acarien cécidogène
Authors: Westphal Evelyne
Published: October 2007

Leaf epidermis cells of Solanum dulcamara cultured for several hours show, after cell wall perforation by Eriophyes cladophthirus, an increase of the vacuolar pH (≥8) both in susceptible and resistant plants. This reaction is more rapid on susceptible plants and the injured cell remains alive. In contrast, on resistant plants, the reaction starts later and the injured cell collapses and dies.
Fire and fungus in a mountain hemlock forest
Authors: Dickman Alan , Cook Stanton
Published: October 2007

Two mortality factors create large-scale pattern in forests of Tsuga mertensiana in subalpine central Oregon Cascade Mountains. Half of an 18 000 - ha study area has experienced stand-destroying fire during the last 500 years. These fires varied in size from 1 to 3200 ha. Individual Phellinus weirii infestations are smaller than most fires and collectively cover less total area, but they are more numerous and fine-grained in their dispersion. Postfire stands are colonized by Pinus contorta, which persists for 2 centuries before being replaced by mountain hemlock. In stands older than 200 years, Phellinus weirii becomes apparent as it spreads from centers and forms patches where it infects trees and alters the plant community. Fungal isolates were collected from 61 infestations; these were subjected to clonal analyses. Spatial dispersion of ramets and genets supports the inference that many infestations are sibling ramets of genets that have survived stand-destroying fire. The age distribution of genets yields the inference that infestations have been initiated or modified by basidiospore infection during the past 1300 years. Several genets are older than 1000 years. Fire has reduced the visible area of infestation of the fungus. It probably has done so by favoring less susceptible host species and by reducing the modal size of dead roots and logs. While repeated fire could reduce the level of fungal infestation, infestations may enhance the probability of stand-destroying fires.
Effects of heavy-metal and SO2 pollution on the concentrations of carbohydrates and nitrogen in tree leaves
Authors: Balsberg-Påhlsson Anna-Maj
Published: October 2007

The concentrations of carbohydrates and nitrogen in leaves or needles of Betula pubescens Ehrh., Betula pendula Roth, Picea abies (L.) Karst., and Pinus sylvestris L. were studied in two industrial areas in Sweden. One of the sites, the Gusum brass foundry in SE Sweden, is polluted by Cu and Zn, the other site, the Rönnskär smelter in NE Sweden, by SO2 in addition to several heavy metal elements. Leaves and needles were sampled during the main growing season at different distances from the sources and analysed for starch, sugars, total nitrogen, and heavy metals. In most leaf or needle samples nearest to the sources, the concentrations of starch and total sugars were significantly higher than in the controls. Of the sugars, sucrose concentration was usually elevated, while glucose and fructose were lower than in the controls. The effects observed were already evident at the beginning of the season, but were usually more pronounced later on. Of the tree species sampled, conifers appeared to be more affected than deciduous trees, and pine more than spruce. The mechanisms of the disturbances are probably complex, but heavy metals and SO2 may inhibit several processes such as hydrolysis of starch and sucrose as well as the transport of sucrose. Increased carbohydrate concentrations may also be secondary effects of a disturbed nitrogen metabolism, as nitrogen concentrations were lower in polluted tree leaves or needles than in controls, and severe inhibition of the soil nitrogen mineralization rate has been recorded in other studies. Key words: starch, sucrose, glucose, fructose, nitrogen, birch, pine, spruce, Cd, Cu, Pb, Zn, SO2.