bluuebunny/crossref_metadata_2025 huggingface dataset:
Identification of a Wzy Polymerase Required for Group IV Capsular Polysaccharide and Lipopolysaccharide Biosynthesis in
Vibrio vulnificus
Authors: Nakhamchik Alina , Wilde Caroline , Rowe-Magnus Dean A.
Published: October 2007

The estuarine bacterium
Vibrio vulnificus
is a human and animal pathogen. The expression of capsular polysaccharide (CPS) is essential for virulence. We used a new mini-Tn
10
delivery vector, pNKTXI-SceI, to generate a mutant library and identify genes essential for CPS biosynthesis. Twenty-one acapsular mutants were isolated, and the disrupted gene in one mutant, coding for a polysaccharide polymerase (
wzy
), is described here. A
wecA
gene initiating glycosyltransferase was among the genes identified in the region flanking the
wzy
gene. This, together with the known structure of the CPS, supports a group IV capsule designation for the locus; however, its overall organization mirrored that of group I capsules. This new arrangement may be linked to our finding that the CPS region appears to have been recently acquired by horizontal transfer. Alcian Blue staining and immunoblotting with antisera against the wild-type strain indicated that the
wzy
::Tn
10
mutant failed to produce CPS and was attenuated relative to the wild type in a septicemic mouse model. Interestingly, immunoblotting revealed that the mutant was also defective in lipopolysaccharide (LPS) production. However, the core-plus-one O-antigen pattern typical of
wzy
mutations was apparent. CPS production, LPS production, and virulence were restored following complementation with the wild-type
wzy
gene. Hence, Wzy participates in both CPS and LPS biosynthesis and is required for virulence in strain 27562. To our knowledge, this is the first functional demonstration of a Wzy polysaccharide polymerase in
V. vulnificus
and is the first to show a link between LPS and CPS biosynthesis.
Studies on bud development in the rhizome of Agropyron repens. II. The effect of the nitrogen supply
Authors: McIntyre Gordon I.
Published: October 2007

Bud growth on isolated rhizomes of Agropyron repens showed a basipetal gradient of decreasing activity and was strongly inhibited at the basal nodes. This evident polarity was correlated with a gradient of decreasing nitrogen content at successively older nodes and with an apparent translocation of nitrogen from the basal to the apical nodes. Isolating the buds from one another reduced growth of the apical buds and prolonged the growth of buds at the basal nodes so that the polarity of bud growth, although still apparent, was much reduced.Supplying nitrogen as NH4NO3 through the cut end of rhizomes still attached to the parent plant caused apical buds to develop as shoots instead of rhizomes. Increasing the nitrogen supply to the rooting medium extended this response to buds at older nodes, restricting rhizome production to basal buds whose growth was inhibited in low nitrogen rhizomes.Buds developing as shoots had a considerably higher total nitrogen and moisture content and a lower dry weight than buds developing as rhizomes.The results emphasized the importance of the nitrogen supply not only in determining the polarity of bud growth and the degree of correlative inhibition, but also as a morphogenetic factor controlling bud development.
Asterobolus: a new parasitic hyphomycete with a novel dispersal mechanism
Authors: Redhead Scott A. , Perrin Peter W.
Published: October 2007

The genus Asterobolus is proposed for an undescribed hyphomycete characterized by multicelled, star-shaped conidia forcibly discharged by a downfolding of the radiating appendages and rupture of the sporogenous cell. Asterobolus gaultheriae sp. nov. is the causal agent of a leaf spot of Gaultheria shallon Pursh. The fungus also infects species of Vaccinium, Pteridium, Malus, and Menziesia. Sclerotia were observed only on Gaultheria and infections of other hosts were found only near infected Gaultheria. In addition to the star-shaped conidia, a Gliocladium-like conidial stage was also observed in cultures of the fungus.
Revision of the genera Sporormia and Sporormiella
Authors: Ahmed S. Iftikhar , Cain R. F.
Published: October 2007

The genus Sporormia is restricted to the type species S. fimetaria DeNot., S. fimicola Ahmed & Asah and S. mirabilis Bret. & Faur., in which the ascospores are arranged in a truncate bundle, parallel to the ascus and surrounded by a common gelatinous sheath. The cells of the ascospores are without germ slits.In Sporormiella, which is regarded as a distinct genus, the ascospores are not arranged in a truncate bundle. Each spore has a distinct and separate gelatinous sheath and each cell of the ascospore has an elongated germ slit. The type species is S. nigropurpurea Ell. & Ev.The following 35 species of Sporormia are transferred to Sporormiella: S. affinis Sacc., S. americana Griff., S. antarctica Speg., S. australis Speg., S. bipartis Cain, S. capybarae Speg., S. chaetomioides Griff., S. commutata Niessl, S. corynespora Niessl, S. dakotensis Griff., S. heptamera Auersw., S. herculea Ell. & Ev., S. insignis Niessl, S. irregularis I. Egel., S. kansensis Griff., S. lageniformis Fuckel, S. lata Griff., S. leporina Niessl, S. longispora Cain, S. megalospora Auersw., S. minima Auersw., S. muskokensis Cain, S. ontariensis Cain, S. ovina (Desm.) Sacc., S pascua Niessl, S. pentamera Oud., S. pilosa Cain, S. pilosella Cain, S. polymera Cain, S. pulchella Hansen, S. pyriformis Speg., S. scandinavica I. Egel., S. schoterriana Bret. & Faur., S. splendens Cain, S. vexans Auersw.There are 22 new species described in the genus Sporormiella, as follows: S. alloimera, S. anisomera, S. calomera, S. cylindrospora, S. cymatomera, S. decamera, S. dodecamera, S. dubia, S. euryspora, S. isomera, S. longisporopsis, S. minimoides, S. minipascua, S. octonalis, S. platymera, S. schadospora, S, septenaria, S. systenospora, S. subtilis, S. teretispora, S. tetramera, S. trogospora.These coprophilous species are from Argentina, Canada, Mexico, and the United States.A total of 66 species are described, 61 of which are illustrated. Keys to the species of Sporormia and Sporormiella are included.
Development and morphology of a chytrid isolated from Bryopsis plumosa
Authors: Kazama Frederick
Published: October 2007

A chytrid tentatively identified as a Phlyctochytrium sp. (isolate 71-1-E) was isolated from Bryopsis plumosa collected in the York River estuary, Virginia (salinity 18–22‰). The morphology of isolate 71-1-E is highly variable and is thought to depend, at least in part, on the substrate. The nature of the rhizoidal system, sporangial size, number and position of the discharge papillae, and the relation of the thallus to substrate were found to vary. Perfusion chamber studies indicate that the germ tube enlarges and is incorporated into the developing sporangium. During discharge pore formation, a rather electrontransparent substance was deposited at the pore site. This was followed by the accumulation of electronopaque substances, rupturing and breaking down of the sporangial wall, and finally the deliquescence of the discharge plug, leading to the formation of the discharge pore.
Ultrastructural observations of soybean leaves affected by bacterial toxemia
Authors: Dueck J. , Zeyen R. J. , Kennedy B. W.
Published: October 2007

Soybean mesophyll cells from stunted and chlorotic trifoliolate leaf tissue affected by bacterial (Pseudomonas glycinea Coerper) induced toxemia, had dense cytoplasm, little vacuolation, chloroplasts with few lamellae, and little starch accumulation. Toxemia-affected cells exhibited no ultrastructural disruptions and resembled very young, healthy mesophyll cells. The main effect of the toxin appears to be a delay in mesophyll cell maturation rather than disruption at the ultrastructural level. Leaf mesophyll cells which had recovered from the bacterial toxemia appeared similar ultrastructurally to mature healthy cells, although they remained smaller.
Le concept d'intégration en écologie appliquée
Authors: Long Gilbert
Published: October 2007

The concept of integration has a wide range of meanings. The author first tries to bring out the point of view of specialists in natural resources. Two approaches are described: on the one hand that proceeding from elementary disciplines or from the nature of variables and on the other hand the ecosystematic or global, multidisciplinary approach. In the first one, integration is made a posteriori by trial and error. More important developments are devoted to the second approach; integration is said to be holistic and proceeds from a priori hypotheses (geomorphological postulate of the Australian school or phytoecological postulate of the Centre d'Etudes Phytosociologiques et Ecologiques Louis Emberger de Montpellier) and a posteriori interpretations. The phyto-ecological approach is especially well developed (vertical vs. horizontal integration). Verified integration is that which proceeds from mathematical models, from historical data, or experimentation.Total integration takes into account contributions from "naturalists" as well as from "humanists."
The relationship between moisture content and net assimilation rate of lichen thalli and its ecological significance
Authors: Kershaw K. A.
Published: October 2007

The relationship between net assimilation rates and percentage thallus saturation has been investigated in 12 widely occurring lichen species in southern Ontario. Optimum net assimilation rates occur between 35 and 70% of thallus saturation levels for different species. A close relationship has been shown to exist between their ecology and the percentage saturation at which maximum assimilation occurs. Optimum net assimilation rate values range from 0.03 mg CO2/g dry weight in Umbilicaria mammulata up to 0.11 mg CO2/g dry weight in Peltigera praetextata. Five of the species also exhibit a plastic physiology in that maximum net assimilation occurs at different levels of thallus saturation in replicates collected from different microhabitats. The implications of this variability are briefly discussed.
The Nidulariaceae or bird's nest fungi of the Hawaiian Islands
Authors: Brodie Harold J.
Published: October 2007

Eleven species of the Nidulariaceae are known to occur in the Hawaiian Islands and are described and illustrated. These are Sphaerobolus stellatus, Cyathus berkeleyanus, C. bulleri, C. poeppigii, C. limbatus, C. microsporus, C. pallidus, C. crassimurus, C. triplex, C. earlei, C. stercoreus. All are widely distributed elsewhere in the tropics except C. crassimurus, a recently described species from Hawaii.
A histochemical study of starch, lipids, and certain enzymes in senescing rose stems
Authors: Molnar J. M. , Parups E. V.
Published: October 2007

The starch, lipid, cytochrome oxidase (EC 1.9.3.1), succinic dehydrogenase (EC 1.3.99.1), peroxidase (EC 1.11.1.7), and acid phosphatase (EC 3.1.3.2) levels were determined periodically by histochemical methods in transverse sections of cut stem of the rose, Rosa hybrida L. cv. Forever Yours, kept in water or in an aqueous preservative solution containing 4% sucrose, 100 ppm sodium isoascorbate, and 100 ppm 8-hydroxyquinoline sulfate. Senescence of the cutrose stem, including leaves and flowers, was delayed by use of the sugar solution. The levels of cytochrome oxidase and succinic dehydrogenase were not significantly affected by either of the treatments. Starch, lipid, peroxidase, and acid phosphatase levels decreased in the tissues of rapidly senescing stems kept in water. In tissues where senescence was retarded by use of sugar solutions the lipid content and peroxidase were maintained at a relatively high level; starch, and acid phosphatase levels steadily increased. It is suggested that in cut rose stems, the onset or retardation of senescence is not related to the activities of acid phosphatase or peroxidase.
Nutrient cycling in a Carex lacustris wetland
Authors: Bernard John M. , Solsky Betsy A.
Published: October 2007

Seasonal changes in aboveground and belowground life history of Carex lacustris were determined and used to study primary production and nutrient cycling in the ecosystem. Seasonal aboveground production was estimated to be about 965 g/m2 per year, with a peak rate of 20.9 g/m2 per day reached in late July. Belowground production was estimated to be 208 g/m2 per year for a total production estimate of 1173 g/m2 per year.Nitrogen, phosphorus, and potassium begin the season with high percentage concentrations in green overwintering shoots but the percentages decline to only about one-third of the original at death in December. Early growth in spring is characterized by a redistribution of these nutrients in the shoots, some translocation from belowground tissues, and uptake from the soil. Calciumand magnesium do not show any important translocation patterns during the year.The yearly budget of uptake and loss of nutrients during a year is estimated to be 15.9 g/m2 nitrogen, 1.9 g/m2 phosphorus, 16.6 g/m2 potassium, 2.9 g/m2 calcium, and 1.5 g/m2 magnesium.
Zygosporogenesis in Gilbertella persicaria
Authors: O'Donnell K. L. , Ellis J. J. , Hesseltine C. W. , Hooper G. R.
Published: October 2007

Zygospore development in Gilbertella persicaria (Eddy) Hesseltine was studied by light microscopy and by transmission and scanning electron microscopy. Cell walls of apically conjugating progametangia lose their separate identities in the fusion septum. Gametangial septa are formed, asynchronously to synchronously, on either side of the fusion septum by the centripetal coalescence of vesicles. Secondary thickening of these septa is more rapid and continues longer on the side towards the zygospore. The multilayered wall of the zygosporangium ultimately consists of outer and inner primary walls, a warted layer, and a smoothing or tertiary layer. Ahyaline quaternary layer with conical projections (zygospore wall) is formed within the zygosporangium. The observations obtained are correlated with existing ultrastructural information on zygosporogenesis in the Mucorales.
Standing stock, community structure, species composition, distribution, and primary production of natural populations of phytoplankton in the southern Beaufort Sea
Authors: Hsiao Stephen I. C. , Foy Malcolm G. , Kittle Douglas W.
Published: October 2007

Standing stock and in situ primary production of the southern Beaufort Sea phytoplankton were determined during the summers of 1973, 1974, and 1975. They decreased with increasing distance from shore and the Mackenzie river mouths. The phytoplankton community was composed largely of diatoms and flagellates with diatoms dominating in the coastal waters and flagellates being more abundant in the waters farther off shore. Dinoflagellates and chrysophytes occurred in relatively low numbers except in a few cases when blooms were observed. Blue-green algae were found occasionally in very low numbers. Seventy-two species of phytoplankton were identified, most of these being diatoms.
Respiration of field-grown loblolly pine roots as influenced by temperature and root type
Authors: Barnard E. L. , Jorgensen J. R.
Published: October 2007

Respiration was determined manometrically for 136 samples of field-grown loblolly pine roots collected over a period of several months. Mean [Formula: see text] values ranged from 0.028 to 3.68, depending upon root size, type, mycorrhizal condition, and temperature. Roots with vigorous, active mycorrhizae respired more than twice as fast, on a dry weight basis, than roots with less vigorous mycorrhizae or no mycorrhizae. Unsuberized root-tip meristems respired several times faster than roots of any other type.
Doneggia complura gen. et sp. nov., a filicalean fern from the Upper Pennsylvanian of Ohio
Authors: Rothwell Gar W.
Published: October 2007

The recent discovery of numerous permineralized frond segments in Upper Pennsylvanian sediments provides an opportunity to describe a new genus of the Sermayaceae and further enhance our knowledge of Paleozoic filicaleans. Specimens of Doneggia complura gen. et sp. nov. consist of up to three orders of biseriately branched frond segments with abaxial curvature of the vascular strand in proximal pinnae and large sori of superficially borne sporangia on laminar pinnules. Sori occur on pinnule lobes below vascular bundles and consist of about 25–35 sporangia. Individual sporangia are oblong, 0.6 mm long and 0.45 mm in maximum diameter, and are attached by a short stalk. As in Sermaya, the horizontal–oblique annulus consists of two rows of interfingering cells and is interrupted at one side by a narrow band of longitudinally oriented, thin-walled cells that presumably acts as a zone of dehiscence. Also, as in Sermaya, the vascular bundles have adaxially disposed protoxylem strands and crowded bordered pits on walls of the metaxylem tracheids. Spores are radial, trilete, triangular in polar view, and measure 45–63 μm in diameter. Material of this type helps demonstrate that some taxa that are currently assigned to the Coenopteridales actually represent vegetative organs of Paleozoic filicaleans.
Habit of the Upper Triassic Pekinopteris auriculata
Authors: Delevoryas T. , Hope R.C.
Published: October 2007

Pekinopteris auriculata, from the Upper Triassic of North Carolina, has once-pinnate leaves attached in crowded fashion on a branched, apparently fleshy rhizome. Some of the leaves may have exceeded 40 cm in length and bear elongated pinnules, each with a main vein and sparse, ascending, anastomosing laterals. Portions of the rhizome bore roots, while other portions lacked them. One possible interpretation is that the proximal part of the rhizome may have been attached to some kind of substrate, with a distal portion that was partially erect or extending away from the substrate. Evidence seems to point toward an affinity of Pekinopteris with the ferns rather than with seed plants. Pekinopteris, along with many other ferns, probably contributed to the 'ground cover' of Upper Triassic landscapes.
Ontogeny of progymnosperms. II. Shoots of Upper Devonian Archaeopteridales
Authors: Scheckler Stephen E.
Published: October 2007

A consistent pattern of variation of the primary xylem has been documented for most levels of the shoot system of Archaeopteris and for smaller pieces of Callixylon (Archaeopteridales). In general, there is a decrease in diameter of primary xylem from major to minor units of branching. Variation, however, exists in each category of branching. Primary xylem of ultimate and penultimate branches of Archaeopteris is smallest in diameter and number of sympodia (or ridges of the stele) proximally and distally and is largest in midregions. Leaves have much smaller traces with the greatest diameter of their xylem at the base; the traces then contracting with each more distal forking. Thus branches show epidogenetic, menetogenetic, and apoxogenetic changes in xylem and seem to be indeterminate at first but eventually become determinate. Leaves show only apoxogenesis and are clearly both fully determinate and appendicular. Judging from the diameter of its trace, one may speculate that the type of organ a primordium would become was determined by its volume and was related to the overall size of its parental axis. On this basis, therefore, one would expect that small axes might have had apices that bore only small, bilaterally symmetrical primordia that were determinate and that grew into leaves. Apices of larger axes might have borne small, determinate primordia (to leaves) and larger, radially symmetrical, and potentially indeterminate primordia which grew into branches. The number and arrangement of branches vary as the diameter of the parental axes increases; small axes have no branches; larger axes bear two orthostichies of branches on opposite surfaces: still larger axe s bear three or more orthostichies of branches in an irregular but dorsiventral pattern. Organotaxy is most regular in small axes and becomes increasingly irregular in larger ones. Orthostichy fractions are mostly non-Fibonacci and fall into an anomolous series. Number and arrangement of sympodia usually correspond to the orthostichies of appendages except in regions of expansion or contraction of the primary xylem where the number of sympodia may temporarily be greater than the orthostichies. Analysis of the histology of the primary xylem tracts of Aneurophytales and Archaeopteridales suggests that the eustele of progymnosperms might have developed in response to a gradual reduction of auxin produced by the shoot promeristems such that the primary vasculature of an axis differentiated increasingly under the influence of auxins from appendage primordia and with greater quantities of internal xylem parenchyma. Trace-bearing sympodia would thus have been isolated into a system like that of Callixylon. The anatomical variation now documented for Archaeopteris suggests that some or all of the criteria used to maintain Svalhardia, Actinopodium, Eddya, Siderella, and Actinoxylon as genera separate from Archaeopteris are suspect.
Buried viable propagules in native prairie and adjacent agricultural sites in central Saskatchewan
Authors: Archibold O. W.
Published: October 2007

Soil cores to a depth of 10 cm taken from native prairie and three adjacent agricultural sites were tested for the presence of buried viable propagules by stimulating germination from the samples in the laboratory. A total of 739 individuals per square metre emerged from the native prairie samples with 476 individuals per square metre from the grazed pasture, 520 individuals per square metre from the wheat stubble, and 1667 individuals per square metre from the summer fallow site. In addition, vegetative regeneration, mostly for grasses and sedges, was important in the native prairie and grazed pasture sites, giving rise to 694 and 2154 individuals per square metre, respectively. Nongerminating seeds were recovered at rates, per square metre, of 19 for native prairie, 387 for grazed pasture, 685 for wheat stubble, and 1007 for summer fallow. It is concluded that various cultural and chemical practices have altered the natural buried propagule complement of the region with the populations of weed seeds building up in the soil as cultivation continues.
Effect of naphthalene and aqueous crude oil extracts on the green flagellate Chlamydomonas angulosa. IV. Decreases in cellular manganese and potassium
Authors: Hutchinson T. C. , Hellebust J. A. , Soto C.
Published: October 2007

The effect of exposure to naphthalene and to aqueous extracts of crude oil on contents of manganese and potassium in cells of Chlamydomonas angulosa has been measured simultaneously by neutron activation analysis. Decreases of both manganese and potassium from treated cells commenced within a very short time of treatment initiation, and may be due to hydrocarbon-induced membrane damage. In control experiments, manganese uptake into cells was found to be light dependent, and potassium uptake was even more so. In cells treated with a 100% saturated naphthalene solution in Bold's basal medium (BBM), little cellular manganese remained after 6 h of exposure and less than 2% was left within 24 h. Potassium loss was even more rapid and complete. Rates of loss for both elements in a 50% saturated naphthalene solution in BBM and in an aqueous crude oil extract were slower but showed a similar pattern. For potassium in both light or dark exposures, an initial increase in cellular content occurred. Sodium acetate was added to assess heterotrophic growth, and the effects of this addition on the loss of the two elements are discussed. Over a short time, it appeared to act as an alternative to light energy in restoring membrane function.
Auxin–cytokinin interaction in the inhibition, release, and morphology of gametophore buds of Plagiomnium cuspidatum from apical dominance
Authors: Nyman L. P. , Cutter E. G.
Published: October 2007

Observations were made on the effects of indoleacetic acid (IAA), kinetin (K), benzyladenine (BA), and triiodobenzoic acid (TIBA) on the lateral buds of decapitated and intact gametophores of Plagiomnium cuspidatum (Hedw.) Kop. Gametophores were cultured in both solid and liquid Parker's nutrient medium and treated with hormones either in solution or in lanolin paste. Based on numbers of activated buds counted from day 16 to 24, it appeared that IAA, K, and BA, when supplied to the decapitated stump, can to varying degrees replace the inhibitory influence of the apical bud. Closer study, however, of activated and inhibited lateral buds suggests that only IAA in the presence of a cytokinin can maintain inhibition in a morphological and anatomical state which is similar to that of intact control plants. Treatment of intact gametophores with TIBA increased bud activation below the treatment ring. Based on bud morphology and anatomical observations in conjunction with records of bud activation response, endogenous auxins and cytokinins appear to be at suboptimal concentrations for growth at inhibited bud sites.
A methodological problem in genecology. Seeds versus clones as source material for uniform gardens
Authors: Hume L. , Cavers P. B.
Published: October 2007

Plants derived from both achenes and rootstock cuttings (ramets) were used to examine genetically based differences between two populations of Rumex crispus L. from two contrasting habitats, i.e., flood plain and pasture. Offspring from both sources were grown under cultivation in a uniform garden. Fifty-eight characters were determined for each individual. Within the pasture population only, seedling offspring differed significantly from plants obtained from ramets. Characteristics of the two populations were compared using (i) seedling offspring and (ii) ramets. More significant differences were found in the former set of comparisons.In the harsh but predictable flood plain habitat, genetic heterogeneity within the population was less than that found among plants from the pasture. Reasons for this difference are discussed.
Genetics of Gracilaria tikvahiae (Rhodophyceae). VII. Further observations on mitotic recombination and the construction of polyploids
Authors: Meer John P. van der
Published: October 2007

Tetrasporophytes of the marine red alga Gracilaria tikvahiae produce spermatia as well as tetraspores. It has been demonstrated previously that these spermatia are diploid and are produced as a consequence of mitotic recombination in somatic cells of the fertile thallus. It has now been demonstrated that female tissue is also present, often adjacent to the male tissue as would be expected, but is more difficult to recognize because it rarely becomes fertile. However, it was found that female tissue could be excised from the tetrasporophyte and induced to regenerate into complete fronds. Crossing experiments indicated that this female tissue was functional and diploid like the corresponding male tissue. Diploid male and female fronds have been established in culture as free-living plants. Morphological mutants of Gracilaria were found useful in obtaining stocks of diploid gametophytes. Triploid and tetraploid sporophytes were readily synthesized by using the diploid gametophytes (or spermatia from normal diploid tetrasporophytes) in crosses to each other or to normal haploid gametophytes. In one case an apparent tetraploid was synthesized by crossing a haploid female with a triploid tetrasporophyte. In this work polyploid designations are made on the basis of the method of construction and the reproductive behaviour of the polyploids. Cytological confirmation (made for a triploid previously) is incomplete for tetraploids but supports the designations that have been made.
Studies of root function in Zea mays. II. Dimensions of the root system
Authors: Miller D. M.
Published: October 2007

Seminal roots of Zea mays were fixed, tied in a bundle with all branches parallel to the main stem, and embedded in Spurr's medium by a slow infusion method. The embedded root system was sectioned transversely at several points along its length. Two types of measurements were made on the sections. First, the number of root cross sections in each of several size classes, based upon root diameters, was determined so as to obtain the total length (per gram total weight) of root branches of a given diameter. Second, 12 root cross sections of various sizes were selected for further measurements. These included the cross sectional areas of the cortex, endodermis, stele, and xylem vessels, together with the circumferences of the cells and vessels in each region. From this information the total cell surface area, both outside and inside the Casparian strip, was calculated and used to express in absolute terms the various parameters measured previously.
Comparison of germination of Cladosporium herbarum and Botrytis cinerea conidia in vitro in relation to nutrient conditions on leaf surfaces
Authors: Wildman H. G. , Parkinson D.
Published: October 2007

Conidia of Cladosporium herbarum and Botrytis cinerea differed in their ability to germinate in water. Potassium nitrate, glucose, and carbohydrate mixtures at concentrations similar to carbon and nitrogen levels on leaf surfaces were tested for their effect on germination and subsequent germ tube growth. For both fungi, all the treatments increased the rate of germination. The treatments also stimulated the total percentage germination of C. herbarum conidia. Glucose, a glucose – potassium nitrate solution, and carbohydrate mixtures stimulated both germ tube production and total germ tube lengths of conidia of C. herbarum. Botrytis cinerea conidia produced multiple germ tubes per conidium in distilled water, potassium nitrate, and carbohydrate mixtures. Glucose and glucose – potassium nitrate solutions stimulated production of a single germ tube per conidium. All treatments stimulated germ tube growth of B. cinerea conidia.
Changes in leaves of susceptible and resistant Solanum dulcamara infested by the gall mite Eriophyes cladophthirus (Acarina, Eriophyoidea)
Authors: Westphal E. , Bronner R. , Ret M. Le
Published: October 2007

Eriophyes cladophthirus perforates the wall of epidermis cells during feeding on young susceptible leaves and provokes the formation of cone-shaped feeding punctures. Callose is detected near the puncture after 20 min and the injured cells are transformed into nutritive cells. Nutritive cells are induced near the feeding sites on susceptible plants, whereas only necrotic cells appear near feeding sites on resistant plants.Mites feeding on resistant plants rapidly initiate a hypersensitive response detectable after 10 min on injured epidermal cells which then leads to severe necrosis of surrounding tissues after 1 h. No typical feeding punctures or callose deposits appear on injured cell walls. Polyphenolic compounds are detected in the necrotic region after 4 h.
Ultrastructure of Filobasidiella arachnophila
Authors: Khan Saeed R. , Kimbrough James W. , Kwon-Chung K. J.
Published: October 2007

Filobasidiella arachnophila differs from other species of the genus in the absence of a "cryptococcoid" anamorph, in the lack of clamp connections in the hyphae, and in its inability to hydrolyze urea, oxidize phenolic compounds, and synthesize starch. Its septal ultrastructure, however, is similar to that of F. neoformans as well as species of Trichosporon, Trichosporonoides, Tremella, Tilletia, Moniliella, and Hyalodendron, all of which have a flared (dolipore) septum without the pore caps (parenthesomes) typical of most higher basidiomycetes. This type of septal pore apparatus is typical of the Filobasidiaceae and a number of yeastlike genera of uncertain affinities. The final generic position of F. arachnophia must await determination of whether the spores formed in this species are mitospores or meiospores.
The conjugation process in the jelly fungus Sirobasidium magnum
Authors: Flegel T. W.
Published: October 2007

The formation of conjugation tubes in yeast cells of the jelly fungus Sirobasidium magnum (Basidiomycotina) was shown to be mediated by diffusible pheromones which passed through dialysis membranes of 12 000 to 14 000 daltons molecular exclusion limit. The yeast cells were responsive to pheromone only in G1 of the cell division cycle. Although caffeine induced morphological abnormalities in the yeast cells and although conjugation tube formation was catabolically repressed by glucose, evidence for the involvement of cyclic nucleotides as secondary messengers in conjugation tube induction was negative. There was some evidence for the presence of a conjugation inhibitor(s).
Inheritance of photoinhibition of conidial development in Cochliobolus miyabeanus
Authors: Chang H. S.
Published: October 2007

Analysis of the photoreaction of single-ascospore isolates from the cross between isolates UK-13 and WK1C of Cochliobolus miyabeanus revealed that photoinhibition of conidial development and light dependence for conidiophore induction are each controlled by a pair of allelic genes, which may be located on different chromosomes or far apart on a single chromosome. In this preliminary survey, each ascus, which contained five to seven ascospores, gave nearly equal numbers of photoinhibited and nonphotoinhibited as well as light-dependent and light-independent single-ascospore isolates.
Microsporogenesis in Larix laricina
Authors: Hall J. Peter
Published: October 2007

Microsporogenesis was studied in Larix laricina in eastern Newfoundland at weekly intervals from October to April in four successive seasons. Male strobili were fixed in a 3:1 ethanol – propionic acid mixture, stained in alcoholic carmine, and squashed in 45% acetic acid.Pollen mother cells began development from interphase in early October and passed through leptotene, zygotene, and pachytene by mid-November. They remained in diplotene until mid-March to early April when meiosis was completed over a 2-to 4-week period. Microspores were produced by early May. The pattern of meiotic divisions, their duration, and variability within and between trees in L. laricina was similar to those reported for L. decidua, L. kaempferi, L. sibirica, and L. eurolepis.Deviation from the normal pattern occurred infrequently. In six trees the "resting diplotene" of winter was interrupted on one occasion and some male strobili had a "delayed meiosis" which occurred several days after meiosis in all other sampled strobili. Abnormal chromosome separations were observed on a few occasions; these consisted mostly of lagging chromosomes, a common abnormality in Larix meiosis. The implications for pollen development and seed yield are discussed.La microsporogénèse chez Larix laricina dans l'est de Terre-Neuve a été étudiée à intervalles hebdomadaires d'octobre à avril, pendant quatre années successives. Les strobiles mâles étaient fixés dans un mélange 3 : 1 d'éthanol – acide propionique, colorés au carmin alcoolique et écrasés dans l'acide acétique 45%.
Morphogenesis of the spikelets and inflorescence of Andropogon gerardii Vit. (Gramineae) and the relationship between form, information theory, and thermodynamics
Authors: Maze Jack , Scagel R. K.
Published: October 2007

The spikelets of Andropogon gerardii occur in pairs, one sessile and one pedicellate. The first glume of the sessile spikelet is bikeeled. The fertile lemma of the sessile spikelet is awned and the awn develops after the lemma has been initiated. The paleas of both spikelets initiate at two positions, are bikeeled, and, on occasion, are two-parted as a result of an interrupted zone of initiation. Each functional lodicule of A. gerardii is developmentally similar to one keel of the palea that has become thickened as a result of activity of an adaxial meristem. The spikelet pairs develop from one primordium. At early stages, spikelet pair primordia about each other along the inflorescence axis and the spikelets of a pair are not separated by a pedicel. The pedicel and the axis of the inflorescence develop through intercalary growth. Differences between appendages in the spikelet of A. gerardii can be viewed as the result of differing amounts of developmental activity (apical growth, marginal meristem, adaxial meristem) common to phyllomic structures. These common developmental activities are, in turn, the result of certain patterns of cell division and cell growth. The evolution of form thus results from alteration of common developmental events. When viewed in such a manner, the evolution of form is seen to be the modification of the informational entropy in an organism. With evolution, there are increases and decreases in informational entropy but, generally speaking, more complex organisms have higher entropy.
Morphologie, structure et ontogénie des nectaires floraux de l’Ailanthus glandulosa
Authors: Bory Gérard , Clair-Maczulajtys Danielle
Published: October 2007

Staminate and hermaphroditic flowers show an hypogynous disc which is composed of two separate parts, an apical and a basal part. These histologic zones should be considered as nectaries. They differ by their position, their shape, and the content and state of differentiation of their cells. Basal nectaries are not vascularized but phloem bundles reach the tip of the disc. Initiation of nectariferous tissue occurs after that of the floral parts. The basal nectaries appear first but the number of cells still increases during the formation of the apical part of the disc. Both basal and apical nectaries have a superficial origin. Numerous anomocytic stomata are present especially on the surface of the apical nectaries; they are rounded and keep their stomatal pores open. On basal nectaries, however, they occur much less frequently.
Wilts caused by Verticillium species. A cytological survey of vascular alterations in leaves
Authors: Robb Jane , Smith Alexandra , Busch Lloyd
Published: October 2007

Plants that are infected with fungi of the species Verticillium frequently develop foliar disease symptoms which may include one or more of the following: flaccidity, drying, chlorosis leading to necrosis, vascular browning, epinasty, and leaf abscission. A number of ultrastructural and chemical alterations occur in the vascular tissues of such leaves: deposition of brown pigments, coating of xylem vessel walls with abnormal material (i.e., lipid-rich coatings or fibrillar coatings), plugging of xylem vessels with gums, gels or tyloses, degeneration of parenchyma cells, and accumulation of abnormal electron dense materials in primary and secondary cell walls. Different host–parasite combinations exhibit different leaf symptoms and different cytological alterations. The purpose of the present survey was to determine whether the extent of any of the possible vascular alterations in leaves could be correlated with the wilting tendency of the host.Chrysanthemums, snapdragons, eggplants, sunflowers, potatoes, sycamore maples and hedge maples were infected with V. dahliae; alfalfa and hops were infected with V. albo-atrum. When leaf symptoms were well advanced, samples were taken from the major lateral leaf veins and were prepared for light (LM) and transmission electron microscopy (TEM) or scanning electron microscopy (SEM). The various types of alterations in the vascular tissues were identified by a correlated LM–TEM method and (or) SEM analysis and for each sample vein the proportion of vessels affected by each type of alteration was calculated. Four leaf samples, each from different plants, were analysed for each host. The visual symptoms, including vascular browning, were estimated subjectively. The degree of leaf flaccidity was correlated positively with the proportion of lipid-coated vessels and inversely with the degree of vascular browning. No other correlations were observed.
Cell-associated and extracellular cellulolytic enzyme activity in the marine fungus Dendryphiella arenaria
Authors: MacDonald Malcolm J. , Speedie Marilyn K.
Published: October 2007

Cellulolytic activity in Dendryphiella arenaria was demonstrated by its ability to release dye from dyed crystalline cellulose and to produce cell-associated and extracellular enzymes when grown on a similar substrate. Exoglucanase was found only in an insoluble form, associated with the hyphae and cellulose particles following sonic disruption of the cells. Endoglucanase was predominantly cell free but with a small amount associated with the cell fractions. High β-glucosidase activity was seen in the filtrate and cell fractions, although in the soluble intracellular fraction its activity disappeared with time. Optimal pH activities for exoglucanase and endoglucanase were demonstrated to be 7.0 and 5.8, respectively. Temperature optima of the enzyme components also differed; maximum exoglucanase activity in the cell-associated fractions and endoglucanase activity in the cell-associated and filtrate fractions occurred at 65 and 60 °C, respectively. Maximum β-glucosidase activity in the filtrate and soluble intracellular fractions occurred at 55 °C and that in the particulate fraction occurred at 60 °C.
Effects of root environment on the kinetics of 1st month growth and nodulation of alfalfa
Authors: Macdowall F. D. H.
Published: October 2007

Measurements were made of plant, root, and nodule dry matter, nodule number, acetylene reduction by nitrogenase, plant N content, and shoot height of Medicago sativa L. cv. Algonquin and expressed chiefly as rate constants of growth (k1′). The effects of the nature and quantity of solid substratum, of the form and concentration of combined N and of symbiotic and non-symbiotic growth, were compared in optimum growth room conditions. Plants grew at the same maximum k1′ in vermiculite with or without gravel and in a soil mix when supplied with 15 mM NO3− in the nutrient solution. Plant growth was retarded with decreasing pot size but maximum nodule growth k1′ occurred in 7-cm pots. Nodulation and nitrogenase activity showed maximum k1′ with least added N but moderate additions produced larger yields of roots and nodules. Plant growth in dry matter and N content, expressed as k1′, yield, or absolute rate (k1′∙yield), was under no circumstance increased by symbiosis in this phase of exponential growth. Nodulation was completely inhibited by 15 mM NO3− and higher concentrations of N were generally inhibitory. A transient, postgerminative treatment with 15 mM NO3− provided a sustained boost to growth. Combined N supplied as NO2− or NH4+ at 15 mM in the nutrient solution without NO3− suported k1′ values comparable to those obtained with less than 1.5 mM NO3−.
Tristyly in Pontederia cordata (Pontederiaceae)
Authors: Price Steven D. , Barrett Spencer C. H.
Published: October 2007

Pontederia cordata L. (Pontederiaceae) is a perennial, entomophilous, emergent aquatic and possesses a tristylous breeding system. A survey of 74 North American populations indicates that populations usually contain the three floral morphs. A strong pollen trimorphism is associated with differences in stamen and style length among the morphs. Pollen size is proportional to stamen height, while pollen production is inversely proportional. There are two size classes of anthers in P. cordata. Long-level anthers of mid- and short-styled plants and mid-level anthers of the short-styled morph are significantly larger than short-level anthers of long- and mid-styled plants and the mid-level anthers of the long-styled morph. The larger mid-level anthers of the short-styled morph produce nearly twice as many pollen grains as the equivalent level in the long-styled morph. It is suggested that this difference may be associated with varying patterns of stamen insertion and development in the floral morphs.Comparisons of various reproductive parameters among the floral morphs in natural populations suggest that there are no significant differences in flowering patterns, inflorescence and flower production, seed production, and germination levels. In addition, bumble bees show no apparent preferences among the floral morphs during foraging activity. Tristyly appears to be a relatively stable breeding system in P. cordata in comparison with tristylous species of the related Eichhornia.
Dinoflagellate cyst terminology: a discussion and proposals
Authors: Sarjeant William A. S.
Published: October 2007

This paper constitutes an attempt to stabilize and expand the descriptive terminology applied to dinoflagellate cysts. The "para" terminology of Evitt et al. (1977, Geol. Surv. Pap. Geol. Surv. Can. 76) is critically reviewed; use of the terms "paraplate," "parasuture," "paratabulation" is endorsed, but the terms "paracingulum" and "parasulcus" and their derivatives are rejected. A new terminology is proposed to characterize the fashions in which paratabulation is expressed. The terms used to define the principal cyst lineages are redefined and their interrelationships summarized. Continued use of the terms "epitract" and "hypotract," "endoblast," and "periblast" is urged.In the course of a discussion of paraplate terminology, the problem of deciding what constitutes a plate or paraplate "series" is considered and a definition attempted. New definitions are presented thereafter for "preapical," "postapical," and "preantapical" paraplates and new names are proposed for the two further additional series present on some rhaetogonyaulacoid cysts. The problems of designation presented by the last apical and first postcingular paraplates of gonyaulacoids are discussed.Revised definitions, in accord with present usage, are proposed for the cyst categories "proximate," "proximochorate," and "chorate." Revised definitions are also presented for five existing types of proximochorate and chorate cysts and three new categories are distinguished. The taxonomic problem presented by membranate cysts is discussed. The various types of cavate cyst are illustrated and nine new terms proposed to identify types not hitherto distinguished. Contraction of the terms "endoarchaeopyle" and "periarchaeopyle," respectively, to "endopyle" and "peripyle," is suggested; and simpler names are proposed for the cingulum and sulcus on endoblast and periblast.The terminology applied to the small preformed openings in cavate cysts is reviewed and arbitrary limits suggested for use in designating horn lengths. A new descriptive terminology for crests and septa is presented. The terminology applied to processes and process tips is reconsidered, additional terms being proposed.
Spore morphology in the Dicksoniaceae. II. The genus Cibotium
Authors: Gastony Gerald J.
Published: October 2007

Species of the dicksonioid genus Cibotium occur in the Hawaiian Islands, Central America – Mexico, and Southeast Asia – Western Malaysia. All investigated specimens produce 64-spored sporangia and the sodium hydroxide assay demonstrates a more or less granular perine deposition over the exine in mature or slightly immature spores. This perine form is shared with the other dicksonioid genera Thyrsopteris and Cystodium and with Metaxya and Lophosoria, two genera of problematical affinity which are palynologically more dicksonioid than cyatheoid. The spores of all Cibotium species show some degree of distal ridge development. The least pronounced ridges occur in Central American – Mexican specimens, but most spores from that region have conspicuous distal ridges whose degree of development intergrades with that of Hawaiian material, whereas the greatest degree of distal as well as equatorial ridge development occurs in the species of Southeast Asia – Western Malaysia. Margo development is variable but is also most pronounced in the species in Southeast Asia – Western Malaysia where it is comparable to that of Lophosoria. All investigated specimens show some degree of pitting of the margo, particularly near and parallel to the laesurae. The number of recognized Cibotium species varies considerably with author and the genus as a whole is in need of modern revisionary work.
Vanterpoolia, a new genus of sporodochial hyphomycetes
Authors: Funk A.
Published: October 2007

Vanterpoolia, a new genus of sporodochial hyphomycetes, is erected for a fungus occurring on necrotic, newly flushed needles of western hemlock (Tsuga heterophylla (Raf.) Sarg.) in coastal British Columbia, Canada. The genus is characterized by triradiate conidia or rodlike, appendaged conidia produced in acropetal chains from simple, septate conidiophores arising from a pseudoparenchymatous stroma. A single species, Vanterpoolia tsugae n.sp., is described.