bluuebunny/crossref_metadata_2025 huggingface dataset:
Ultrastructure of freeze-substituted appressoria produced by aeciospore germlings of the rust fungus Arthuriomyces peckianus
Authors: Swann E. C. , Mims C. W.
Published: October 2007

Aeciospores of Arthuriomyces peckianus germinated readily on moist strips of dialysis membrane and developing appressoria were observed within 3 to 6 h after spores were deposited on membranes. A single germ tube typically emerged from each binucleate spore and grew until its tip contacted the dialysis membrane. The germ tube tip was then transformed into a swollen appressorium that adhered tightly to the membrane, apparently as a result of an extracellular material that surrounded the appressorium base. Virtually all the spore cytoplasm and both nuclei moved into the germ tube and developing appressorium. Following a synchronous mitotic division of the two nuclei, a septum formed to delimit the now tetranucleate appressorium from the germ tube. As the appressorium matured, an apparently wall-less region developed in the central portion of the appressorium appressed against the dialysis membrane. In this region the fungus plasma membrane appeared to make direct contact with the underlying dialysis membrane. A funnel-like or cone-like structure referred to as the appressorial cone then developed in the wall-less region. The appressorial cone extended up into the cytoplasm of the appressorium and was lined by the fungal plasma membrane. Numerous branched elaborations of the plasma membrane were associated with the inner portion of the cone. Key words: rust fungus, infection structures, electron microscopy.
The effects of aluminum and calcium on the growth and nutrition of selected ectomycorrhizal fungi of jack pine
Authors: Browning Mark H. R. , Hutchinson Thomas C.
Published: October 2007

The influence of Al and Ca on the growth, in axenic culture, of three ectomycorrhizal fungi associated with jack pine (Pinus banksiana Lamb.) was examined. Isolates of Hebeloma crustuliniforme (St. Amans) Quél., Rhizopogon rubescens (Tul.) Tulasne, and Suillus tomentosus (Kauff.) Singer, Snell & Dick were obtained from basidiocarps collected in jack pine stands of different ages. Basidiocarps and the soil surrounding them were analyzed for Al and Ca, as well as other elements. Each fungal species was grown for 4 weeks in nutrient solutions containing 37, 185, 370, or 740 μM Al combined in a factorial design with 25, 125, 250, or 500 μM Ca and maintained at pH 3.8. Growth of all three fungal species was reduced at 370 μM Al. Significant interaction was found between fungal species and Al treatment for all six elements measured in mycelial tissue. Stepwise increments in external Al concentration resulted in reduced mycelial concentrations of Ca, Mg, and K, and increased mycelial concentrations of Al, P, and Fe in H. crustuliniforme. High external Al levels resulted in reduced mycelial concentrations of all elements measured except Al and P in R. rubescens. In contrast, for S. tomentosus the same external Al levels increased the mycelial concentrations of all elements except Ca. The response of the three ectomycorrhizal fungi to Ca also differed. Growth of H. crustuliniforme was stimulated by stepwise increments in external Ca concentrations from 25 to 500 μM. Increments in calcium had no effect on the growth of R. rubescens. High external levels of Ca acted synergistically with high external Al concentrations to reduce growth by S. tomentosus. Unlike the other two species, the response of S. tomentosus to Al and Ca could not have been predicted from the soil and basidiocarp analyses. Alterations in Ca to Al ratios of soils may influence the succession of ectomycorrhizal fungi on conifer root systems. Key words: ectomycorrhizae, jack pine, aluminum, calcium, basidiocarps.
Statut endomycorhizien du genre Oidiodendron
Authors: Dalpé Yolande
Published: October 2007

The endomycorrhizal status of 11 species of Oidiodendron has been verified under axenic growing conditions. Characteristic hyphal coils of ericoid mycorrhiza developed inside root cortical cells of blueberry (Vaccinium angustifolium Ait.) seedlings when these were inoculated with five of the tested species. These species are, in order of their endomycorrhizal potential, O. periconioides, O. scytaloides, O. chlamydosporicum, O. citrinum, and O. flavum. The present survey increases to 10 the number of Oidiodendron species or their associated teleomorphs known to produce ericoid mycorrhiza. Key words: Oidiodendron spp., O. periconioides, O. scytaloides, Ericoid mycorrhizae.
Cluster analysis of late Holocene pollen trends in Ontario
Authors: Campbell Ian D. , McAndrews J. H.
Published: October 2007

Cluster analysis of Ontario pollen stratigraphies demonstrates similar regional successions during the past 1000 years. Seven character states qualitatively describe the behaviour of the pollen percentage trends for each taxon: 0, absent; 1, present with no visible trend but high noise; 2, rising through time; 3, falling through time; 4, rise–fall; 5, fall–rise; and 6, stable through time. The three similarity indices (S) used were of the form S equals the number of characters in agreement divided by the number of informative characters. The three clustering techniques used are single linkage, complete linkage, and unpaired weighted geometric mean analysis. Single linkage and unpaired weighted geometric mean analysis showed a north–south division with all three indices; complete linkage showed only rare local groupings with all three indices. The division between the two clusters falls just south of Lake Nipissing. All successions indicate climatic cooling; the clusters reflect southward movement of the centres of species abundances, particularly white pine. The method identifies regions of similar vegetation dynamics. Key words: cluster analysis, forest dynamics, Holocene, Little Ice Age, Ontario, palynology.
Recovery of gravitropism after basipetal centrifugation in protonemata of the moss Ceratodon purpureus
Authors: Walker Loni M. , Sack Fred D.
Published: October 2007

Apical cells of 5-day-old dark-grown protonemata of the moss Ceratodon purpureus (Hedw.) Brid. are negatively gravitropic and appear to utilize amyloplasts as statoliths. These cells exhibit a characteristic plastid zonation (five zones) with one zone (No. 3) specialized for the lateral sedimentation of amyloplasts. Basipetal centrifugation displaces all amyloplasts in the apical cell to the end wall. In basipetally centrifuged protonemata observed using infrared videomicroscopy, tip extension occurred with or without amyloplasts present in the apical dome. The initial return of upward curvature was always correlated with the return and sedimentation of amyloplasts in zone 3. Subsequent vigorous upward curvature was correlated with distinct amyloplast zonation and further sedimentation in zone 3. Initial downward (“wrong way”) curvature, which often preceded upward curvature, correlated with the presence of amyloplasts in the apical dome (zone 1). These data support the hypotheses that nonsedimenting amyloplasts in zone 1 are necessary for initial downward curvature and that amyloplast sedimentation in zone 3 is necessary for upward curvature. Key words: gravitropism, moss, protonema, amyloplast, statolith, centrifugation.
Rajeunissement chez le Sequoia sempervirens: effets du microgreffage in vitro
Authors: Tranvan H. , Bardat F. , Jacques M. , Arnaud Y.
Published: October 2007

In vitro micrografting of Sequoia sempervirens was used as a rejuvenation method: apices were collected from in vitro cultured shoots issued from a 500-year-old tree; the rootstocks originated from a 1-year-old tree. Only a few grafted apices survived. Once producing leafy shoots, they exhibited some juvenile morphological and physiological characteristics. Some scions were isolated and rooted in a new medium. Although the restoration of the orthotropy is very difficult, a few of the rooted plantlets were orthotropic and this characteristic was maintained after acclimatization in greenhouses. Therefore, the in vitro micrografting of Sequoia sempervirens can be considered as a rejuvenation method that must be improved. Key words: Sequoia sempervirens, in vitro micrografting, rejuvenation, orthotropy.
La végétation forestière du delta de Lanoraie, Québec
Authors: Lamontagne L. , Camiré C. , Ansseau C.
Published: October 2007

The vegetation and the soil characteristics of the sandy terraces of the Lanoraie Delta, Quebec, were sampled at 84 forest sites using the methods of Whittaker and Canada Soil Information System. The ordination results show that the soil moisture regime (xeric–hydric) and the pH (3.5–5.0) are the main factors responsible for the spatial distribution of the vegetation. When these results (ordination analysis) and those of the cluster analysis are superimposed, the relationship between the five vegetation groups studied and particular ecological conditions can be seen. Thus, two groups of vegetation dominated by conifers are found in the middle of the terraces. One of these is dominated by Tsuga canadensis and the other by Abies balsamea and Picea rubens. These two groups are found on podzolic, gleyed soils with a mounded microrelief, which are strongly acidic (pH < 3.5) and have a hydric–mesic moisture regime. The remaining three vegetation groups are dominated by deciduous species. Among these, two groups arise from human activities such as logging or farming. One of these is dominated by Fagus grandifolia, Acer saccharum, Acer rubrum, and Quercus rubra and is composed of mature trees. The other is dominated by Pinus strobus, Polulus grandidentata, Populus tremuloides, or Betula papyrifera and is composed of young trees. These two types occupy the edge of the terraces where the topography is flat and the soil podzolic with a moderately to slightly acidic pH (4.0–5.0) and a xeric–mesic moisture regime. Finally the third group, dominated by Acer rubrum, is found on medium acidic (pH = 4.0), gleyed soils with a hydric–mesic moisture regime. This study shows that Acer rubrum is the best suited species for sandy, acidic, and nutrient-poor sites of the Lanoraie Delta. Key words: Lanoraie Delta, multivariate analysis, vegetation classification, Acer rubrum.
Paleophycology of Long Lake, Saint John County, New Brunswick, Canada, based on diatom distribution in sediments
Authors: Rawlence David J.
Published: October 2007

The succession of postglacial diatom communities was determined in a 5.98 m core from Long Lake, New Brunswick, Canada. The base of the core was dated at 12 200 ± 150 BP. Five major communities were identified: (zone A) from the base to 520 cm, a pioneer Fragilaria/Cyclotella association; (zone B) from 520 to 380 cm, commencing ca. 10 000 BP, a Melosira ambigua/Synedra ulna/Cyclotella/Asterionella community; (zone C) from 380 to 260 cm, a Fragilaria pinnata/Cyclotella pseudostelligera/Tabellaria flocculosa community; (zone D) from 260 to 80 cm, an Asterionella formosa/Cyclotella pseudostelligera/Fragilaria pinnata/Tabellaria flocculosa v. flocculosa community; followed by (zone E) in the upper 80 cm, an Asterionella formosa/Cyclotella meneghiniana/Fragilaria pinnata/Cyclotella pseudostelligera community corresponding with the period of the modern spruce–hardwood community on land. The period of greatest change in the limnic community (zone D) appears to correspond to the period of greatest change in the terrestrial flora, and the mid Holocene Hypsithermal warm peak. The Younger Dryas climatic cooling (ca. 11 000 – 10 000 BP) is preceded by the development of a Fragilaria pinnata/Fragilaria construens/Cyclotella stelligera community, followed by an Ellerbeckia arenaria v. teres biozone, although the Younger Dryas sediments are actually devoid of diatoms. There is evidence of some climatic oscillation following the Younger Dryas period, and some evidence that the climatic cooling began prior to deposition of the mineral layer widely associated with the Younger Dryas throughout the Maritime Provinces of Canada. Key words: paleophycology, diatoms, Younger Dryas, eastern Canada.
Floral development of two species of Stylidium (Stylidiaceae) and some remarks on the systematic position of the family Stylidiaceae
Authors: Erbar Claudia
Published: October 2007

The early floral development of Stylidium adnatum and Stylidium graminifolium is characterized by an initial circular primordium whose areas in the transversal plane of the floral primordium show enhanced growth. The spiral inception of the five sepals starts before the differentiation of the initial circular primordium into two stamen primordia in transversal position (in relation to the floral diagram) and the corolla ring primordium below the stamen primordia. Then five petal primordia, which alternate with the sepals, arise on the corolla ring primordium (early sympetaly). Peculiar to the flowers of Stylidiaceae is the column that bears at its top both stigma and anthers. Probably this column should be interpreted as a receptacular tube. No distinct carpel primordia have been observed. The inferior ovary results from intercalary growth in the peripheral parts of the receptacle below the calyx, corolla, and stamen primordia. The residual floral apex gives rise to a transversal septum, by which the ovary becomes bilocular. None of the morphological, palynological, and embryological characters discussed contradicts a position of the Stylidiaceae near the Campanulales, and several of these characters support this position. Key words: Stylidiaceae, Campanulales, floral development, systematic position, floral biology.
Seed reserves and early symbiotic protocorm development of Platanthera hyperborea (Orchidaceae)
Authors: Richardson K. A. , Peterson R. L. , Currah R. S.
Published: October 2007

Seeds of the terrestrial orchid Platanthera hyperborea consist of a thin testa and a simple embryo without a cotyledon. Epidermal and parenchyma cells of the embryo contained lipid and protein as storage reserves. Many of the protein bodies had globoid crystals identified by their P, Ca2+, Mg2+, and K+ content. Germination occurred with either Rhizoctonia cerealis or Ceratorhiza goodyerae-repentis as the fungal symbiont on Warcup's medium. The fungus entered through dead suspensor cells and triggered protocorm development and concomitant utilization of lipid and protein reserves. Fungal hyphae formed pelotons with protocorm cells initially, and these went through stages of vacuolation and collapse. Some hyphae stored small numbers of polyphosphate bodies. Clumps of degenerated hyphae were usually encased within material that stained positive with aniline blue, presumably callose. Key words: Platanthera, orchid, seed, protocorm, endophytic fungus.
A major floristic boundary in Minnesota: an analysis of 280 taxa occurring in the western and southern portions of the state
Authors: Wheeler G. A. , Cushing E. J. , Gorham E. , Morley T. , Ownbey G. B.
Published: October 2007

A prominent floristic boundary is identified by combining distribution maps based on herbarium records of 280 taxa that occur in western and southern Minnesota. A set of boundary dots was plotted for each taxon with the help of a grid overlay, and the coordinates of the dots in the set were tabulated and mapped by computer. The map shows a band of concentration of species limits that runs roughly north–south in the west and bends eastward in the central and eastern parts of the state. When subsets of the 280 taxa based on habitat preference are mapped independently, the band remains distinct. Single factors of climate and landscape alone are inadequate to explain the position and strength of the floristic boundary. The next most simple hypothesis proposes that the boundary results from an abrupt change in ecosystem type, from a woodland kept open by the interaction of fire with vegetation, topography, and soils to a closed forest where fire was less frequent. The concentration of limits implies that for many species migration had reached an equilibrium with ecosystem factors under the present climate. Key words: phytogeography, flora, tension zone, Minnesota.
Chemosystematic studies in the genus Pinus. VII. The leaf oil terpene composition of ponderosa pine, Pinus ponderosa
Authors: Rudloff Ernst von , Lapp Martin S.
Published: October 2007

The leaf oil terpene composition of ponderosa pines (Pinus ponderosa Laws.) from 37 sites west of the Continental Divide north of 42°, 5 sites east of the Divide in Montana, and 1 each from the Black Hills, South Dakota, Wilkerson Pass, Colorado, and Grand Canyon, Arizona was determined. Tree-to-tree variation was quite low, as was between-population variability at all northwestern locations. Quantitative and qualitative differences in several leaf oil terpenes were found between these and the eastern populations, which lends strong support to the taxonomic separation of ponderosa pine into the typical variety ponderosa and the northeastern var. scopulorum. Intermediate leaf oil terpene compositions were found in several trees near the Continental Divide, indicating that there is a transition between these two varieties. Whereas the Black Hills and Wilkerson Pass samples had terpene compositions that were similar to those of trees from eastern Montana, those from the Grand Canyon area differed quantitatively, indicating that a bridge to the southeastern var. arizonica may be found in the leaf oil composition as well. Key words: ponderosa pine, terpenes, leaf oil, varieties, geographic distribution, chemosystematics.
Comparative seed morphology of Thuja occidentalis (eastern white cedar) from upland and lowland sites
Authors: Briand Christopher H. , Posluszny Usher , Larson Douglas W.
Published: October 2007

As part of an investigation of the extent of habitat-specific variation in Thuja occidentalis L., cones were collected from cliff (dry upland) and swamp (wet lowland) sites in southern Ontario. The number of seeds per cone, number of fully developed seeds per cone, seed fresh weight, length, and width, length and width of embryo area, and length and width of right wing were determined. Seed yield on a per cone basis did not vary between habitat types or among sites within habitats. There was, however, significant variation among trees within sites. Individual seed characters did not vary between habitat types, but significant variation existed among sites within habitats, among trees within sites, and among cones within trees. Only the width of right wing failed to show cone to cone variation within individual trees. The majority of explainable variance for all characters could be apportioned to trees within sites. This and a relatively low degree of cone to cone variation suggest that the seed morphological characters were under strong maternal control. Differences among sites are thought to be the result of local environmental variation rather than genetic differences. The lack of habitat-specific seed character variation indicates that contrasting moisture regimes have little effect on quantitative seed morphology. No evidence exists for ecotypic variation with respect to seed morphology. Key words: Thuja occidentalis, eastern white cedar, seed morphology, ecotypes, cliff, swamp.
Application of an osmium-maceration technique to observe plant–microbe interfaces of Italian ryegrass and crown rust fungi by scanning electron microscopy
Authors: Koga Hironori , Tsukiboshi Takao , Uematsu Tsutomu
Published: October 2007

The osmium-maceration technique (osmium–DMSO–osmium method) was used to observe intracellular structures of Italian ryegrass leaves infected with crown rust fungus (Puccinia coronata Corda var. coronata) by scanning electron microscopy. Prolonged maceration with dilute osmium removed the cytoplasmic matrix, and intracellular structures were disclosed in a bold relief. The three-dimensional configuration of nuclei, mitochondria, the endoplasmic reticulum, and other structures of host and parasite cells were visible. Key words: scanning electron microscopy (SEM), osmic maceration, intracellular structure, Puccinia coronata, Italian ryegrass.
Field nodules of Alnus incana ssp. rugosa and Myrica gale exhibit pronounced acetylene-induced declines in nitrogenase activity
Authors: Schwintzer Christa R. , Tjepkema John D.
Published: October 2007

The time course of acetylene reduction was examined in field nodules of speckled alder (Alnus incana ssp. rugosa (Du Roi) Claus.) and sweet gale (Myrica gale L.) with an open flow-through system. When detached speckled alder nodules were measured in the laboratory, there was an initial peak rate of nitrogenase activity between 2 and 3 min followed by pronounced declines to 50% of the peak rate (early summer) and 66% (late summer) at 9 min, after which there was little further change. Speckled alder nodules measured in the field while still attached to the plant also had a peak rate between 2 and 3 min. Most sweet gale nodules had a peak rate at 2–3 min and a sharp decline to 27% at 21 min followed by a partial recovery to 49% at 60 min. The time courses of field nodules of speckled alder and sweet gale were comparable with those of intact, growth chamber grown seedlings. The initial peak rate is the most accurate measure of nitrogenase activity and the only reliable way to measure this is with an open, flow-through system. We describe a simple, inexpensive, flow-through system for use in the field. Key words: acetylene-induced decline, Alnus incana ssp. rugosa, actinorhizal plants, Myrica gale, nitrogen fixation, nitrogenase activity.
Growth ofPseudotsuga menziesiiandTsuga heterophyllaseedlings along a light gradient: resource allocation and morphological acclimation
Authors: Mailly D. , Kimmins J. P.
Published: October 2007

Silvicultural alternatives that differ in the degree of overstory removal may create shady environments that will be problematic for the regeneration of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco). Gradients of light in the field were used to compare mortality, growth, and leaf morphological acclimation of two conifer species of contrasting shade tolerances: Douglas-fir and western hemlock (Tsuga heterophylla (Raf.) Sarg.). Results after two growing seasons indicated that Douglas-fir mortality occurred mainly at relative light intensity (RLI) below 20%, while western hemlock mortality was evenly distributed along the light gradient. Height, diameter, and biomass of the planted seedlings increased with increasing light for both species but at different rates, and maximum biomass accumulation always occurred in the open. Douglas-fir allocated more resources to stem biomass than western hemlock, which accumulated more foliage biomass. Increases in specific leaf area for Douglas-fir seedlings occurred at RLI ≤ 0.4 and red/far red (R/FR) ratio ≤ 0.6, which appear to be the minimal optimum light levels for growth. Conversely, western hemlock seedlings adjusted their leaf morphology in a more regular pattern, and changes were less pronounced at low light levels. These results, along with early mortality results for Douglas-fir, suggest that the most successful way to artificially regenerate this species may be by allowing at least 20% of RLI for ensuring survival and at least 40% RLI for optimum growth. Key words: light, light quality, leaf morphology, acclimation.
Ultrastructure of compatible and incompatible interactions of soybean roots infected with the plant pathogenic oomycete Phytophthora sojae
Authors: Enkerli K. , Mims C. W. , Hahn M. G.
Published: October 2007

Compatible and incompatible interactions of two soybean isolines containing either Rps1a or Rps1b resistance genes with races 2 and 8 of Phytophthora sojae were examined by light and electron microscopy. Phytophthora sojae race 2 is virulent on Rps1b plants and avirulent on Rps1a plants. Race 8 shows the reverse reaction; it is avirulent on Rps1b plants, but virulent on Rps1a plants. All combinations of races and cultivars were examined at times ranging from 30 min to 20 h postinoculation. Zoospore encystment, germination, and infection occurred within 30 min in all interactions. No evidence of appressorium formation was found. Wall appositions in epidermal cells adjacent to hyphae were very frequent by 30 min postinoculation. Differences between compatible and incompatible interactions became evident as early as 4 h postinoculation. The major difference appeared to relate to timing of host responses, which lead to two different types of relationships. In compatible interactions, P. sojae exhibited a short biotrophic phase with the establishment of many haustoria without triggering visible plant responses in cortical cells until approximately 10 h postinoculation. By 15 h postinoculation, almost the entire root was necrotic, wall appositions were abundant, and vascular tissue was colonized. The incompatible interaction was characterized by a nearly complete absence of haustoria, rapid host cell necrosis, and formation of many wall appositions by 4 h postinoculation. The pathogen rarely penetrated beyond the endodermis of the resistant host and colonization of vascular tissue was rare. Overall there were clear ultrastructural differences between compatible and incompatible interactions of soybean with P. sojae. These data support a strong correlation of resistance with host cell death, formation of wall appositions, and absence of root stele colonization. Key words: Phytophthora sojae, Glycine max, host–pathogen interaction, ultrastructure.
Immunogold localization of callose and other plant cell wall components in soybean roots infected with the oomycetePhytophthora sojae
Authors: Enkerli K. , Mims C. W. , Hahn M. G.
Published: October 2007

Immunolabeling and transmission electron microscopic techniques were used to investigate the chemical nature of wall appositions in roots of susceptible and resistant soybean plants inoculated with Phytophthora sojae race 2. The extrahaustorial matrix associated with the haustorium of Phytophthora sojae also was examined. Antibodies against (1 → 3)-β-glucan, a terminal α-fucosyl-containing epitope present in xyloglucan and rhamnogalacturonan I, and an arabinosylated (1 → 6)-β-galactan epitope present in arabinogalactan proteins were used. (1 → 3)-β-Glucan (callose), xyloglucan, and arabinogalactan proteins were found to be localized in all wall appositions regardless of how long after inoculation the appositions developed or whether plants were susceptible or resistant to Phytophthora sojae. (1 → 3)-β-Glucan also was found in fungal walls and at host cell plasmodesmata. None of the four antibodies labeled the extrahaustorial matrix. The antibody against arabinogalactan protein recognized the host plasma membrane, but not the invaginated host plasma membrane associated with the extrahaustorial matrix. This result indicates that the properties or the composition of the host plasma membrane may change locally once it becomes an extrahaustorial membrane. Key words: Phytophthora sojae, Glycine max, callose, immunolabeling, wall appositions, papillae.
Fungal endophytes from the roots of alpine and boreal Ericaceae
Authors: Hambleton Sarah , Currah Randolph S.
Published: October 2007

Oidiodendron mains Barron, Scytalidiutn vaccinii Dalpé, Litten, & Sigler, and a variable white taxon (VWT) were isolated consistently from the roots of ericaceous plants collected in three different habitats. Restriction fragment length polymorphism data were used to (i) clarify the identification of strains of O. maius with character states intermediate between O. maius and Oidiodendron griseum Robak, (ii) identify the VWT as distinct from S. vaccinii in spite of cultural similarities, and (iii) reveal that S. vaccinii comprises two genotypes correlated with habitat. Corn meal agar was used to induce conidiogenesis in S. vaccinii, and one strain produced apothecia consistent with the description of Hymenoscyphus ericae (Read) Korf & Kernan, confirming the anamorph–teleomorph relationship of these two taxa. Oidiodendron maius and S. vaccinii, already accepted as mycobionts of the Ericaceae, are confirmed as ubiquitous in natural habitats of Alberta and are often both isolated from the same root fragment. The isolation of Phialocephala fortinii Wang & Wilcox, a non-mycorrhizal endophyte of diverse plant families, from two of the sites but not from the acidic wetland indicates that its distribution depends on edaphic factors. Its vigorous growth on the initial isolation plates adversely affected the recovery of the other three taxa. Key words: ericoid mycorrhiza, Ericaceae, RFLP, Oidiodendron, Scytalidium, Hymenoscyphus, Phialocephala.
Les Refractohilum (Hyphomycètes, Moliniacés) à conidies pluriseptées en Europe et au Canada
Authors: Roux Claude , Bricaud Olivier , Coeur Didier Le , Etayo Javier
Published: October 2007

A comparative study of Refractohilum specimens with pluriseptate conidia from Canada and western Europe shows that they belong to three species: R. achromaticum, known until now only from Canada, Refractohilum intermedium Roux et Etayo sp.nov., known from subhumid parts of southern Europe (Mediterranean areas of France and Spain), and Refractohilum pluriseptatum Etayo et Roux sp.nov., known from western Europe and the most humid parts of southern Europe. These three species, which grow on the thallus of corticolous and often sterile crustose lichens with Trentepohlia, differ from each other by dimensions and septation of conidia and conidiophores, distribution, and ecology. Key words: lichenicolous fungi, Refractohilum, taxonomy.
DENSITY OF DARK MATTER IN THE SOLAR SYSTEM AND PERIHELION PRECESSION OF PLANETS
Authors: KHRIPLOVICH I. B.
Published: October 2007

Direct model-independent relation between the secular perihelion precession of a planet and the density of dark matter ρ dm at its orbit is indicated, and used to deduce upper limits on local values of ρ dm .
Regulation of Airway Mucin Gene Expression
Authors: Thai Philip , Loukoianov Artem , Wachi Shinichiro , Wu Reen
Published: October 2007

Mucins are important components that exert a variety of functions in cell-cell interaction, epidermal growth factor receptor signaling, and airways protection. In the conducting airways of the lungs, mucins are the major contributor to the viscoelastic property of mucous secretion, which is the major barrier to trapping inhaled microbial organism, particulates, and oxidative pollutants. The homeostasis of mucin production is an important feature in conducting airways for the maintenance of mucociliary function. Aberrant mucin secretion and accumulation in airway lumen are clinical hallmarks associated with various lung diseases, such as asthma, chronic obstructive pulmonary disease, cystic fibrosis, emphysema, and lung cancer. Among 20 known mucin genes identified, 11 of them have been verified at either the mRNA and/or protein level in airways. The regulation of mucin genes is complicated, as are the mediators and signaling pathways. This review summarizes the current view on the mediators, the signaling pathways, and the transcriptional units that are involved in the regulation of airway mucin gene expression. In addition, we also point out essential features of epigenetic mechanisms for the regulation of these genes.
Microbial manipulation of the rat dam changes bacterial colonization and alters properties of the gut in her offspring
Authors: Fåk Frida , Ahrné Siv , Molin Göran , Jeppsson Bengt , Weström Björn
Published: October 2007

The impact of an altered bacterial colonization on gut development has not been thoroughly studied, despite the increased risk of certain diseases with a disturbed microbiota after birth. This study was conducted to determine the effect of microbial manipulation, i.e., antibiotic treatment or Escherichia coli exposure, of the dam on bacterial colonization and gut development in the offspring. Pregnant rats were administered either broad-spectrum antibiotics 3 days before parturition or live nonpathogenic E. coli Culture Collection of University of Göteborg, Sweden type strain (CCUG 29300T) 1 wk before parturition and up to 14 days of lactation in the drinking water. Cecal bacterial levels, gut growth, intestinal permeability, digestive enzyme levels, and intestinal inflammation were studied in 2-wk-old rats. Pups from dams that were antibiotic-treated had higher densities of Enterobacteriaceae, which correlated with a decreased stomach growth and function, lower pancreatic protein levels, higher intestinal permeability, and increased plasma levels of the acute phase protein, haptoglobin, compared with pups from untreated mothers. Exposure of pregnant/lactating mothers to E. coli CCUG 29300T, also resulting in increased Enterobacteriaceae levels, gave in the offspring similar results on the stomach and an increased small intestinal growth compared with the control pups. Furthermore, E. coli pups showed increased mucosal disaccharidase activities, increased liver, spleen, and adrenal weights, as well as increased plasma concentrations of haptoglobin. These findings indicate that disturbing the normal bacterial colonization after birth, by increasing the densities of cecal Enterobacteriaceae, appears to have lasting effects on the postnatal microflora, which affects gut growth and function.
Altered anti-inflammatory response of mononuclear cells to neuropeptide PACAP is associated with deregulation of NF-κB in chronic pancreatitis
Authors: Michalski Christoph W. , Selvaggi Federico , Bartel Michael , Mitkus Tomas , Gorbachevski Andrej , Giese Thomas , Sebastiano Pierluigi Di , Giese Nathalia A. , Friess Helmut
Published: October 2007

Although it is recognized that neurogenic influences contribute to progression of chronic inflammatory diseases, the molecular basis of neuroimmune interactions in the pathogenesis of chronic pancreatitis (CP) is not well defined. Here we report that responsiveness of peripheral blood mononuclear cells (PBMC) to the neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP) is altered in CP. Expression of PACAP and its receptors in human CP was analyzed with quantitative RT-PCR, laser-capture microdissection, and immunohistochemistry. Regulation of PACAP expression was studied in coculture systems using macrophages and acinar cells. Responsiveness of donor and CP PBMC to PACAP was determined based on cytokine profiles and NF-κB activation of LPS- or LPS+PACAP-exposed cells. Although donor and CP PBMC responded equally to LPS, PACAP-mediated counteraction of LPS-induced cytokine response was switched from inhibiting TNF-α to decreasing IL-1β and increasing IL-10 secretion. The change of PACAP-mediated anti-inflammatory pattern was associated with altered activation of NF-κB: compared with LPS alone, a combination of LPS and PACAP had no effect on NF-κB p65 nuclear translocation in CP PBMC, whereas NF-κB was significantly decreased in donor PBMC. According to laser-capture microdissection and coculture experiments, PBMC also contributed to generation of a PACAP-rich intrapancreatic environment by upregulating PACAP expression in macrophages encountering apoptotic pancreatic acini. The nociceptive status of CP patients correlated with pancreatic PACAP levels and with IL-10 bias of PACAP-exposed CP PBMC. Thus the ability of PBMC to produce and to respond to PACAP might influence neuroimmune interactions that regulate pain and inflammation in CP.
A quantitative comparison of rates of phagocytosis and digestion of apoptotic cells by macrophages from normal (BALB/c) and diabetes-prone (NOD) mice
Authors: Marée Athanasius F. M. , Komba Mitsuhiro , Finegood Diane T. , Edelstein-Keshet Leah
Published: October 2007

Macrophages play an important role in clearing apoptotic debris from tissue. Defective or reduced clearance, seen, for instance, in non-obese diabetic (NOD) mice, has been correlated with initiation of autoimmune (Type 1) diabetes (T1D) (O'Brien BA, Huang Y, Geng X, Dutz JP, Finegood DT. Diabetes 51: 2481–2488, 2002). To validate such a link, it is essential to quantify the reduced clearance (for example, by comparison to BALB/c control mice) and to determine which elements of that clearance are impaired. Recently, we fit data for the time course of in vitro macrophage feeding experiments to basic models of macrophage clearance dynamics, thus quantifying kinetics of uptake and digestion of apoptotic cells in both mouse strains (Marée AFM, Komba M, Dyck C, Łabeçki M, Finegood DT, Edelstein-Keshet L. J Theor Biol 233: 533–551, 2005). In the cycle of modeling and experimental investigation, we identified the importance of 1) measuring short-, intermediate-, and long-time data (to increase the accuracy of parameter fits), and 2) designing experiments with distinct observable regimes, including engulfment-only and digestion-only phases. Here, we report on new results from experiments so designed. In comparing macrophages from the two strains, we find that NOD macrophage engulfment of apoptotic cells is 5.5 times slower than BALB/c controls. Significantly, our new data demonstrate that digestion is at least two times slower in NOD, in contrast with previous conclusions. Moreover, new data enable us to detect an acceleration in engulfment (after the first engulfment) in both strains, but much smaller in NOD macrophages.
Changes in macrovessel pulmonary blood flow distribution following chronic hypoxia: assessed using synchrotron radiation microangiography
Authors: Schwenke Daryl O. , Pearson James T. , Kangawa Kenji , Umetani Keiji , Shirai Mikiyasu
Published: October 2007

Structural and functional changes of the pulmonary circulation, particularly during the pathogenesis of pulmonary arterial hypertension (PAH), remain to be fully elucidated. In this study, we utilized monochromatic synchrotron radiation (SR) microangiography to assess changes in pulmonary arteriole blood flow in the intact-chest rat after 4 wk of chronic hypoxia. Sprague-Dawley rats were exposed to normoxia (N-rats) or chronic hypoxia (10% O2; CH-rats) for 28 days. Rats were anesthetized, and microangiography was performed on the left lung to assess 1) the branching distribution of pulmonary arteriole blood flow (internal diameter >80 μm) and 2) dynamic changes in vessel lumen diameter during acute hypoxic (8% O2 for 4 min) pulmonary vasoconstriction (HPV) before and after β-adrenoceptor blockade (2 mg/kg iv propranolol). Using SR angiography, we observed that the number of opaque third- and fourth-generation vessels (100–300 μm) for CH-rats was significantly fewer than the number for N-rats. The magnitude of HPV was not different between CH-rats and N-rats. β-Adrenoceptor blockade accentuated the HPV in 200- to 300-μm vessels for CH-rats, but even more so in N-rats. However, in CH-rats, β-adrenoceptor blockade also accentuated the HPV in 100- to 200-μm vessels. In summary, we utilized SR to assess gross blood flow changes and functional changes (i.e., HPV) of the pulmonary circulation in PAH. These results highlight the benefits of SR for assessing pulmonary circulatory pathology. Of particular importance, future use of SR will provide an effective method for assessing potential therapeutic treatments for PAH.
Convective oxygen transport and fatigue
Authors: Amann Markus , Calbet Jose A. L.
Published: October 2007

During exercise, fatigue is defined as a reversible reduction in force- or power-generating capacity and can be elicited by “central” and/or “peripheral” mechanisms. During skeletal muscle contractions, both aspects of fatigue may develop independent of alterations in convective O2delivery; however, reductions in O2supply exacerbate and increases attenuate the rate of accumulation. In this regard, peripheral fatigue development is mediated via the O2-dependent rate of accumulation of metabolic by-products (e.g., inorganic phosphate) and their interference with excitation-contraction coupling within the myocyte. In contrast, the development of O2-dependent central fatigue is elicited 1) by interference with the development of central command and/or 2) via inhibitory feedback on central motor drive secondary to the peripheral effects of low convective O2transport. Changes in convective O2delivery in the healthy human can result from modifications in arterial O2content, blood flow, or a combination of both, and they can be induced via heavy exercise even at sea level; these changes are exacerbated during acute and chronic exposure to altitude. This review focuses on the effects of changes in convective O2delivery on the development of central and peripheral fatigue.
Muscle K+, Na+, and Cl− disturbances and Na+-K+ pump inactivation: implications for fatigue
Authors: McKenna Michael J. , Bangsbo Jens , Renaud Jean-Marc
Published: October 2007

Membrane excitability is a critical regulatory step in skeletal muscle contraction and is modulated by local ionic concentrations, conductances, ion transporter activities, temperature, and humoral factors. Intense fatiguing contractions induce cellular K+ efflux and Na+ and Cl− influx, causing pronounced perturbations in extracellular (interstitial) and intracellular K+ and Na+ concentrations. Muscle interstitial K+ concentration may increase 1- to 2-fold to 11–13 mM and intracellular K+ concentration fall by 1.3- to 1.7-fold; interstitial Na+ concentration may decline by 10 mM and intracellular Na+ concentration rise by 1.5- to 2.0-fold. Muscle Cl− concentration changes reported with muscle contractions are less consistent, with reports of both unchanged and increased intracellular Cl− concentrations, depending on contraction type and the muscles studied. When considered together, these ionic changes depolarize sarcolemmal and t-tubular membranes to depress tetanic force and are thus likely to contribute to fatigue. Interestingly, less severe local ionic changes can also augment subtetanic force, suggesting that they may potentiate muscle contractility early in exercise. Increased Na+-K+-ATPase activity during exercise stabilizes Na+ and K+ concentration gradients and membrane excitability and thus protects against fatigue. However, during intense contraction some Na+-K+ pumps are inactivated and together with further ionic disturbances, likely precipitate muscle fatigue.
Radioiodine Labeled Anti-MIF McAb: A Potential Agent for Inflammation Imaging
Authors: Zhang Chao , Hou Gui-hua , Han Jian-kui , Song Jing , Liang Ting
Published: October 2007

Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine that may play a role in the pathogenesis of inflammation. Radiolabeled anti-MIF McAb can be used to detect in vivo inflammatory changes. The objective of this study was to investigate in vivo biology of radioiodinated anti-MIF McAb using the inflammation model mice. Anti-MIF McAb was radioiodinated with Na125I by Iodogen method. Animal models were induced in the mice by intramuscular injection ofS. aureus,E. coli, and turpentine oil. The biodistribution studies with radioiodinated anti-MIF McAb were performed on inflammation mice. The relationship between inflammatory lesions and anti-MIF McAb binding was investigated using the percent of injected dose per gram tissue (% ID/g) of tissue samples and whole-body autoradiography. The radioactivity of125I-anti-MIF McAb in the inflammatory tissue increased gradually for three inflammation models. The highest uptake was found inS. aureusgroup and the lowest was inE. coligroup. The uptake in turpentine oil group was average. Whole-body autoradiography showed that all inflammation foci could be visualized clearly from 24 hours after injection, but 48 hours images were much clearer in accordance with the high T/NT ratio. These results demonstrate the ability of radioiodinated anti-MIF McAb to measure in vivo inflammatory events represented by high expression of MIF and suggests that radiolabeled anti-MIF McAb warrants further investigation as a potential inflammation-seeking agent for imaging to detect inflammatory disorders.
Methods for Stratified Cluster Sampling with Informative Stratification
Authors: Scott Alastair , Wild Chris
Published: October 2007

We look at fitting regression models using data from stratified cluster samples when the
strata may depend in some way on the observed responses within clusters. One important
subclass of examples is that of family studies in genetic epidemiology, where the probability
of selecting a family into the study depends on the incidence of disease within the family.
We develop the survey-weighted estimating equation approach for this problem,
with particular emphasis on the estimation of superpopulation parameters. Full maximum
likelihood for this class of problems involves modelling the population distribution of the
covariates which is simply not feasible when there are a large number of potential covariates.
We discuss efficient semiparametric maximum likelihood methods in which the covariate
distribution is left completely unspecified. We further discuss the relative efficiencies of these
two approaches.
Analysis and Implementation of Gossip-Based P2P Streaming with Distributed Incentive Mechanisms for Peer Cooperation
Authors: Agarwal Sachin , Singh Jatinder Pal , Dube Shruti
Published: October 2007

Peer-to-peer (P2P) systems are becoming a popular means of streaming audio and video content but they are prone to bandwidth starvation if selfish peers do not contribute bandwidth to other peers. We prove that an incentive mechanism can be created for a live streaming P2P protocol while preserving the asymptotic properties of randomized gossip-based streaming. In order to show the utility of our result, we adapt a distributed incentive scheme from P2P file storage literature to the live streaming scenario. We provide simulation results that confirm the ability to achieve a constant download rate (in time, per peer) that is needed for streaming applications on peers. The incentive scheme fairly differentiates peers' download rates according to the amount of useful bandwidth they contribute back to the P2P system, thus creating a powerful quality-of-service incentive for peers to contribute bandwidth to other peers. We propose a functional architecture and protocol format for a gossip-based streaming system with incentive mechanisms, and present evaluation data from a real implementation of a P2P streaming application.
The Activation of Natural Killer Cell Effector Functions by Cetuximab-Coated, Epidermal Growth Factor Receptor–Positive Tumor Cells is Enhanced By Cytokines
Authors: Roda Julie M. , Joshi Trupti , Butchar Jonathan P. , McAlees Jaclyn W. , Lehman Amy , Tridandapani Susheela , Carson William E.
Published: October 2007

Purpose: Natural killer (NK) cells express an activating Fc receptor (FcγRIIIa) that mediates antibody-dependent cellular cytotoxicity (ADCC) and production of immune modulatory cytokines in response to antibody-coated targets. Cetuximab is a therapeutic monoclonal antibody directed against the HER1 antigen. We hypothesized that the NK cell response to cetuximab-coated tumor cells could be enhanced by the administration of NK cell–stimulatory cytokines.

Experimental Design: Human NK cells stimulated with cetuximab-coated tumor cells and interleukin-2 (IL-2), IL-12, or IL-21 were assessed for ADCC and secretion of IFN-γ and T cell–recruiting chemokines. IL-21 and cetuximab were given to nude mice bearing HER1-positive xenografts.

Results: Stimulation of human NK cells with cetuximab-coated tumor cells and IL-2, IL-12, or IL-21 resulted in 3-fold to 10-fold higher IFN-γ production than was observed with either agent alone. NK cell–derived IFN-γ significantly enhanced monocyte ADCC against cetuximab-coated tumor cells. Costimulated NK cells also secreted elevated levels of chemokines (IL-8, macrophage inflammatory protein-1α, and RANTES) that could direct the migration of naive and activated T cells. IL-2, IL-12, and IL-21 enhanced NK cell ADCC against tumor cells treated with cetuximab. The combination of cetuximab, trastuzumab (an anti-HER2 monoclonal antibody), and IL-21 mediated greater NK cell cytokine secretion and ADCC than any agent alone. Furthermore, administration of IL-21 enhanced the effects of cetuximab in a murine tumor model.

Conclusions: These results show that cetuximab-mediated NK cell activity can be significantly enhanced in the presence of NK cell–stimulatory cytokines. These factors, therefore, may be effective adjuvants to administer, in combination with cetuximab, to patients with HER1-positive malignancies.