bluuebunny/crossref_metadata_2025 huggingface dataset:
Simulation and Characterization of Microreactors for Aerosol Generation
Authors: Kockmann Norbert , Dreher Simon , Engler Michael , Woias Peter
Published: September 2008

This paper shows the application of T-shaped micromixers for the generation of nanoscale aerosols by the mixing of a hot gas-vapor-mixture with a cold gas. The fast mixing within a T-shaped micromixer leads to a quasi-instantaneous and high saturation of the vapor and therefore to homogeneous nucleation. After nucleation, the particles grow to their final size until the vapor is saturated. Different mixer geometries, mixing ratios, and gas temperatures have been investigated by numerical simulation to yield optimum mixing results over a wide range of operational parameters. The main selection parameters are the mixing time, the mixing quality, and the flow regimes in the mixer. Six different microreactor geometries were designed and fabricated in silicon and covered with a Pyrex glass lid for optical observation. Special attention was paid to thermal insulation and particle deposition at the channel walls. This concerns not only the entire mixing chip, but also the design of the fluidic mount with only few bends and corners. First experimental results for particle deposition (prefabricated NaCl nanoparticles in a nitrogen carrier stream,) and aerosol generation (Vitamin E droplets in nitrogen) are presented. High temperature gradients up to 1 Mio. K/s lead to a rapid condensation and forming of nanosized particles with a mean diameter of 20 to 50 nm and a narrow size distribution.
Measurement of Local Liquid Temperature Using Micro-Thermocouple in Subcooled Boiling Flow
Authors: Kim Seong-Jin , Park Goon-Cherl
Published: September 2008

In this paper, the developed algorithm was described, which can discriminate the local phase temperature in the two-phase flow measured by a self-manufactured micro-thermocouple. The algorithm used to calculate the temperature of each phase was based on the response time of the micro-thermocouple and the exponential regression method. This algorithm was verified by conducting experiments with an optical chopper and a laser. This algorithm was also applied to the measurement of the liquid temperature in subcooled boiling flow. The liquid temperature was measured by means of a micro-thermocouple which was made of alumel-chromel wire (K-type) with an outer diameter of 12.7 μm had a response time of several milliseconds. Finally, the liquid temperatures estimated by the developed algorithm in the case of subcooled boiling were used to assess the capability of the CFX-4.2 code.
Analysis of a model race car
Authors: Coletta Vincent P. , Evans Jonathan
Published: September 2008

We analyze the motion of a gravity powered model race car on a downhill track of variable slope. Using a simple algebraic function to approximate the height of the track as a function of the distance along the track, and taking account of the rotational energy of the wheels, rolling friction, and air resistance, we obtain analytic expressions for the velocity and time of the car as functions of the distance traveled along the track. Photogates are used to measure the time at selected points along the track, and the measured values are in excellent agreement with the values predicted from theory. The design and analysis of model race cars provides a good application of principles of mechanics and suggests interesting projects for classes in introductory and intermediate mechanics.
Pyrosequencing To Detect Mutations in
FKS1
That Confer Reduced Echinocandin Susceptibility in
Candida albicans
Authors: Wiederhold Nathan P. , Grabinski Jodi L. , Garcia-Effron Guillermo , Perlin David S. , Lee Samuel A.
Published: September 2008

Pyrosequencing was compared to Sanger dideoxy sequencing to detect mutations in
FKS1
responsible for reduced echinocandin susceptibility in
Candida albicans
. These methods were in complete agreement for 10 of 12 clinical isolates with elevated echinocandin MICs, supporting the potential feasibility of pyrosequencing to detect mutations within diploid fungi.
Enhanced Susceptibility to Antifungal Oligopeptides in Yeast Strains Overexpressing ABC Multidrug Efflux Pumps
Authors: Wakieć Roland , Gabriel Iwona , Prasad Rajendra , Becker Jeffrey M. , Payne John W. , Milewski Sławomir
Published: September 2008

The susceptibility to several oligopeptide and amino acid antifungals of a
Saccharomyces cerevisiae
strain carrying multiple deletions in yeast multidrug resistance genes was compared to transformants containing the
CDR1
,
CDR2
, or
MDR1
genes that encode the major
Candida albicans
drug efflux pumps. Recombinant yeast strains overexpressing Cdr1p and Cdr2p showed enhanced susceptibilities to all tested oligopeptide antifungals. The enhanced susceptibilities of multidrug-resistant yeast strains to oligopeptide antifungals corresponded to higher rates of oligopeptide uptake. Yeast cells overexpressing Cdr1p or Cdr2p effluxed protons at higher rates than the reference cells lacking these ABC transporters. An increased plasma membrane electrochemical gradient caused by the functional overexpression of Cdr1p or Cdr2p appeared to increase cellular susceptibility to oligopeptide antifungals by stimulating their uptake via oligopeptide permeases.
Mutation of Two
Mycoplasma arthritidis
Surface Lipoproteins with Divergent Functions in Cytadherence
Authors: Bird Daniel W. , Graber Kelly , Knutson Allison , Washburn Leigh R.
Published: September 2008

Mycoplasma arthritidis
is a natural pathogen of rats, causing an acute polyarthritis. Previous studies identified two membrane-bound lipoproteins, Maa1 and Maa2, thought to be associated with cytadherence of
M. arthritidis
strain 158p10p9. We have since confirmed that Maa1 is a major adhesin, although the role of Maa2 has proven more elusive. Both proteins were capable of eliciting protective immunity in rats against challenge with the virulent strain 158p10p9, suggesting that they may be important in pathogenesis. The purpose of this study was to better understand the roles of Maa1 and Maa2 in cytadherence in vitro. Insertion mutants were created for both genes by transposon mutagenesis. In vitro adherence of the Maa1 mutant KOMaa1 to rat L2 lung cells was reduced to the level previously reported for a spontaneous low-adherence mutant of 158p10p9 in which Maa1 is truncated and nonfunctional. Surprisingly, adherence of the Maa2 mutant KOMaa2 was approximately fivefold greater than that of the wild type. Complementation of KOMaa1 and KOMaa2 with wild-type alleles of
maa1
and
maa2
, respectively, returned adherence to wild-type levels. This work confirms our earlier observation that Maa1 is a major adhesin for
M. arthritidis
strain 158p10p9. Maa2, on the other hand, may play a suppressive or modulatory role, possibly serving to release organisms from microcolonies at certain stages of infection.
Meningococcal Outer Membrane Protein NhhA Is Essential for Colonization and Disease by Preventing Phagocytosis and Complement Attack
Authors: Sjölinder Hong , Eriksson Jens , Maudsdotter Lisa , Aro Helena , Jonsson Ann-Beth
Published: September 2008

Neisseria meningitidis
is a leading cause of meningitis and septicemia worldwide, with a rapid onset of disease and a high morbidity and mortality. NhhA is a meningococcal outer membrane protein included in the family of trimeric autotransporter adhesins. The protein binds to the extracellular matrix proteins heparan sulfate and laminin and facilitates attachment to host epithelial cells. In this study, we show that NhhA is essential for bacterial colonization of the nasopharyngeal mucosa in a murine model of meningococcal disease. Successful colonization depends on bacterial attachment but also to the capacity to overcome innate host immune responses. We found that NhhA protected bacteria from phagocytosis, which is important for the mucosal survival of bacteria. In addition, NhhA mediated extensive serum resistance that increased bacterial survival in blood and promoted lethal sepsis. The presence of NhhA protected bacteria from complement-mediated killing by preventing the deposition of the membrane attack complex. Taken together, the results of this work reveal that NhhA inhibits phagocytosis and protects bacteria against complement-mediated killing, which enhances both nasal colonization and the development of sepsis in vivo.
Important Role for Toll-Like Receptor 9 in Host Defense against Meningococcal Sepsis
Authors: Sjölinder Hong , Mogensen Trine H. , Kilian Mogens , Jonsson Ann-Beth , Paludan Søren R.
Published: September 2008

Neisseria meningitidis
is a leading cause of meningitis and sepsis. The pathogenesis of meningococcal disease is determined by both bacterial virulence factors and the host inflammatory response. Toll-like receptors (TLRs) are prominent activators of the inflammatory response, and TLR2, -4, and -9 have been reported to be involved in the host response to
N. meningitidis
. While TLR4 has been suggested to play an important role in early containment of infection, the roles of TLR2 and TLR9 in meningococcal disease are not well described. Using a model for meningococcal sepsis, we report that TLR9
−/−
mice displayed reduced survival and elevated levels of bacteremia compared to wild-type mice. In contrast, TLR2
−/−
mice controlled the infection in a manner comparable to that of wild-type mice. TLR9 deficiency was also associated with reduced bactericidal activity in vitro, which was accompanied by reduced production of nitric oxide by TLR9-deficient macrophages. Interestingly, TLR9
−/−
mice recruited more macrophages to the bloodstream than wild-type mice and produced elevated levels of cytokines at late time points during infection. At the cellular level, activation of signal transduction and induction of cytokine gene expression were independent of TLR2 or TLR9 in macrophages and conventional dendritic cells. In contrast, plasmacytoid dendritic cells relied entirely on TLR9 to induce these activities. Thus, our data demonstrate an important role for TLR9 in host defense against
N. meningitidis
.
Recombination-Based In Vivo Expression Technology IdentifiesHelicobacter pyloriGenes Important for Host Colonization
Authors: Castillo Andrea R. , Woodruff Andrew J. , Connolly Lynn E. , Sause William E. , Ottemann Karen M.
Published: September 2008

Here we undertook to identify colonization and gastric disease-promoting factors of the human gastric pathogenHelicobacter pylorias genes that were induced in response to the stomach environment. Using recombination-based in vivo expression technology (RIVET), we identified six promoters induced in the host compared to laboratory conditions. Three of these promoters, designated Pivi10, Pivi66, and Pivi77, regulate genes thatH. pylorimay use to interact with other microbes or the host. Pivi10likely regulates themobA,mobB, andmobDgenes, which have potential roles in horizontal gene transfer through plasmid mobilization. Pivi66occurs in the cytotoxin-associated gene pathogenicity island, a genomic region known to be associated with more severe disease outcomes, and likely regulatescagZ,virB11, andvirD4. Pivi77likely regulates HP0289, an uncharacterized paralogue of thevacAcytotoxin gene. We assessed the roles of a subset of these genes in colonization by creating deletion mutants and analyzing them in single-strain and coinfection experiments. We found that amobABDmutant was defective for murine host colonization and that acagZmutant outcompeted the wild-type strain in a coinfection analysis. Our work supports the conclusion that RIVET is a valuable tool for identifyingH. pylorifactors with roles in host colonization.
CadA Negatively Regulates
Escherichia coli
O157:H7 Adherence and Intestinal Colonization
Authors: Vazquez-Juarez Roberto C. , Kuriakose Jeeba A. , Rasko David A. , Ritchie Jennifer M. , Kendall Melissa M. , Slater Terry M. , Sinha Mala , Luxon Bruce A. , Popov Vsevolod L. , Waldor Matthew K. , Sperandio Vanessa , Torres Alfredo G.
Published: September 2008

Adherence of pathogenic
Escherichia coli
strains to intestinal epithelia is essential for infection. For enterohemorrhagic
E. coli
(EHEC) serotype O157:H7, we have previously demonstrated that multiple factors govern this pathogen's adherence to HeLa cells (A. G. Torres and J. B. Kaper, Infect. Immun. 71:4985-4995, 2003). One of these factors is CadA, a lysine decarboxylase, and this protein has been proposed to negatively regulate virulence in several enteric pathogens. In the case of EHEC strains, CadA modulates expression of the intimin, an outer membrane adhesin involved in pathogenesis. Here, we inactivated
cadA
in O157:H7 strain 86-24 to investigate the role of this gene in EHEC adhesion to tissue-cultured monolayers, global gene expression patterns, and colonization of the infant rabbit intestine. The
cadA
mutant did not possess lysine decarboxylation activity and was hyperadherent to tissue-cultured cells. Adherence of the
cadA
mutant was nearly twofold greater than that of the wild type, and the adherence phenotype was independent of pH, lysine, or cadaverine in the media. Additionally, complementation of the
cadA
defect reduced adherence back to wild-type levels, and it was found that the mutation affected the expression of the intimin protein. Disruption of the
eae
gene (intimin-encoding gene) in the
cadA
mutant significantly reduced its adherence to tissue-cultured cells. However, adherence of the
cadA eae
double mutant was greater than that of an 86-24
eae
mutant, suggesting that the enhanced adherence of the
cadA
mutant is not entirely attributable to enhanced expression of intimin in this background. Gene array analysis revealed that the
cadA
mutation significantly altered EHEC gene expression patterns; expression of 1,332 genes was downregulated and that of 132 genes was upregulated in the mutant compared to the wild-type strain. Interestingly, the gene expression variation shows an EHEC-biased gene alteration including intergenic regions. Two putative adhesins, flagella and F9 fimbria, were upregulated in the
cadA
mutant, suggestive of their association with adherence in the absence of the Cad regulatory mechanism. In the infant rabbit model, the
cadA
mutant outcompeted the wild-type strain in the ileum but not in the cecum or mid-colon, raising the possibility that CadA negatively regulates EHEC pathogenicity in a tissue-specific fashion.
Immunization with Recombinant V10 Protects Cynomolgus Macaques from Lethal Pneumonic Plague
Authors: Cornelius Claire A. , Quenee Lauriane E. , Overheim Katie A. , Koster Frederick , Brasel Trevor L. , Elli Derek , Ciletti Nancy A. , Schneewind Olaf
Published: September 2008

Vaccine and therapeutic strategies that prevent infections withYersinia pestishave been sought for over a century. Immunization with live attenuated (nonpigmented) strains and immunization with subunit vaccines containing recombinant low-calcium-response V antigen (rLcrV) and recombinant F1 (rF1) antigens are considered effective in animal models. Current antiplague subunit vaccines in development for utilization in humans contain both antigens, either as equal concentrations of the two components (rF1 plus rLcrV) or as a fusion protein (rF1-rLcrV). Here, we show that immunization with either purified rLcrV (a protein at the tip of type III needles) or a variant of this protein, recombinant V10 (rV10) (lacking amino acid residues 271 to 300), alone or in combination with rF1, prevented pneumonic lesions and disease pathogenesis. In addition, passive immunization studies showed that specific antibodies of macaques immunized with rLcrV, rV10, or rF1, either alone or in combination, conferred protection against bubonic plague challenge in mice. Finally, we found that when we compared the reactivities of anti-rLcrV and anti-rV10 immune sera from cynomolgus macaques, BALB/c mice, and brown Norway rats with LcrV-derived peptides, rV10, but not rLcrV immune sera, lacked antibodies recognizing linear LcrV oligopeptides.
In-transit lymph node metastases in breast cancer: a possible source of local recurrence after Sentinel Node procedure
Authors: van Deurzen C H M , Borgstein P J , van Diest P J
Published: September 2008

Aims:

In-transit lymph node metastases are a common phenomenon in melanoma patients and have been increasingly recognised since the introduction of the Sentinel Node (SN) procedure. To which extent this also occurs in patients with breast cancer has not been studied yet. The aim of this study was therefore to explore the occurrence of in-transit lymph node metastases in patients with breast cancer.

Methods:

Afferent lymph vessels to the SN identified by blue dye were removed from 17 patients with breast cancer during a regular SN procedure.

Results:

Three out of 17 patients showed a lymph node associated with the afferent lymph vessel. One of these lymph nodes showed a breast cancer macrometastasis, to be regarded as an in-transit metastasis. This metastasis would normally have been left in situ.

Conclusions:

In-transit lymph nodes associated with the afferent SN lymph vessels seem to occur in a significant proportion of patients with breast cancer. These lymph nodes may contain metastases, which are a potential source of local recurrence when left in situ. This finding generates the hypothesis that there may be an indication to remove these lymph vessels during the SN procedure.
Diagnosis and management of Whipple’s disease of the brain
Authors: Panegyres P K
Published: September 2008

Whipple’s disease of the brain is one of the most challenging neurological diagnoses. “Is it Whipple’s disease?” is a frequent question, but rarely is the answer yes. The neurological manifestations do not help to distinguish primary from secondary Whipple’s disease of the brain, and although MR brain scanning with gadolinium is mandatory, it can be normal and any abnormalities are non-specific. There must be a comprehensive search for multisystem involvement such as raised inflammatory markers, lymphadenopathy or malabsorption; biopsy of lymph node or duodenum may be necessary. PCR and DNA sequencing forTropheryma whippleion lymphocytes from blood and cerebrospinal fluid is essential. Treatment is as difficult as the diagnosis—there are no randomised controlled trials.
Dark induction of sporulation in Bremia lactucae
Authors: Raffray J. B. , Sequeira Luis
Published: September 2008

Light exerted an inhibitory effect on sporulation of Bremia lactucae Regel on infected lettuce seedlings. Maximum sporulation was obtained in a dew chamber on seedlings exposed to a minimum of 6 h of darkness 7 days after inoculation. Continuous light applied at this time (2000 ft-c) prevented sporulation completely. If no dark period was allowed immediately after inoculation, there was an apparent inhibition of penetration and establishment of the parasite.
An addition to the genus Leptomelanconium Petrak
Authors: Morgan-Jones G.
Published: September 2008

Gloeocoryneum cinereum (Dearn.) Weindlmayr, monotype species of Gloeocoryneum, is transferred into Leptomelanconium as L. cinereum (Dearn.) comb. nov.
Fossil mosses, Beaufort Formation (Tertiary), Northwestern Banks Island, Western Canada Arctic
Authors: Kuc M. , Hills L. V.
Published: September 2008

Thirteen fossil mosses belonging to eight genera were extracted from a woody sapropel found in the upper Beaufort Formation, northwestern Banks Island, Western Canadian Arctic. All belong to extant species.On the basis of the enclosing strata, moss fossils, and associated organic remains it is concluded that the sediments were deposited in a small, shallow body of water, in which lake sedimentation was both preceded and terminated by alluvial sedimentation.
Ultrastructural observations on the mesophyll cells of pine leaves
Authors: Harris William M.
Published: September 2008

The ultrastructure of mesophyll cells of Pinus strobus has been investigated in the spring and winter months. Wall invaginations begin in the early spring and eventually give the cells a lobed appearance. The chloroplasts are of the normal stroma lamella – grana type and completely ring the cells by winter. Lipid globules and electron-dense phenol deposits increase in the winter months.
The influence of tolerant tomato hosts on the pathogenic characteristics of tobacco mosaic virus
Authors: MacNeill B. H. , Fletcher J. T.
Published: September 2008

The susceptible tomato cultivar Craigella and three TMV-tolerant cultivars heterozygous for the genes Tm-1, Tm-2, and Tm-22 respectively, were united by grafting into a bundle of four plants such that the Craigella was in contact with the Tm-1 component, Tm-1 with Tm-2, and Tm-2 with Tm-22. The susceptible component of the graft combination was then inoculated with either strain 0 or strain 1 of tobacco mosaic virus. Subsequently, the effect of host passage was determined by assaying leaf samples from all four components of the graft and then identifying the virus as to pathogenic strain by inoculation to differential hosts. Graft combinations which had received strain 0 inoculum yielded variants which were either strain 1 or 2 or 1.2; grafts originally infected with strain 1 yielded variants which were strain 2 or 1.2. Since no new strains were detected in the susceptible Craigella component it is concluded that the changes in pathogenicity of TMV were mediated by graft passage into tolerant hosts.
Structural and enzymatic characterization of plant zymogen bodies
Authors: Cohen Esther , Shain Y. , Ben-Shaul Y. , Mayer A. M.
Published: September 2008

The zymogen body fraction of pea seeds was further investigated as to the content and localization of additional enzymes. This fraction was previously shown to contain an inactive form of amylopectin-1,6-glucosidase. An acid phosphatase was found with an optimum pH of 5.4. ATP or GTP were the preferred natural substrates, although there was no effect of Mg2+, K+, or Na+ ions on this acid nucleotide phosphatase activity. Cytochemical methods show that the ATPase is membrane-bound and that these bodies have only a single limiting membrane. No RNAse activity could be found; however, there was considerable β-galactosidase activity. It is concluded that these zymogen bodies are a distinct class of subcellular organelles in plants.
Effects of soil water suction, soil temperature, carbon and nitrogen amendments, and host rootlets on survival in soil of zoospores of Phytophthora cactorum
Authors: McIntosh D. L.
Published: September 2008

Zoospores of P. cactorum were added to air-dry soil and recovered periodically on soil-dilution plates. Such inoculum survived longer in relatively dry soil than in wet soil. Temperature at which soil was stored after infestation had little effect on persistence but survival tended to be longer at 10 °C than at 26.7 °C. Adding dextrose or sucrose, and ammonium sulfate, alone or together, had no appreciable effect on fungus survival. Addition of urea, 500 ppm N w/w air-dry soil, shortened considerably the period through which cysts were recovered on dilution plates. This effect was not obtained with urea 250 ppm N. Other common nitrogen fertilizers had no consistent effect on fungus survival. When sprouted apple seeds were planted in soil infested with zoospores, the number of propagules increased substantially and the fungus was recovered for several weeks longer from planted than from non-planted soil. Soil may be infested with P. cactorum more readily by using zoospores than by using other propagules.
A monograph of the genus Drummondia
Authors: Vitt Dale H.
Published: September 2008

Six species and one variety are recognized in a worldwide study of the genus Drummondia. The genus is placed in its own subfamily, the Drummondoideae Vitt, most closely related to the Macromitrioideae. The new combination Drummondia sinensis var. ussuriensis (Broth.) Vitt is made and recorded from eastern U.S.S.R. The Japanese material of Drummondia is considered within the concept of D. sinensis and is shown, by use of a scatter diagram, to be different from the eastern North American D. prorepens. A key to the taxa is given and a complete taxonomic diagnosis is presented for each taxon with comments about its distribution and critical features. The geographical distributions of the taxa indicate that the genus was a part of a circumpolar Arcto-Tertiary flora.
Understory biomass in five forest types in southwestern Nova Scotia
Authors: Telfer E. S.
Published: September 2008

A reconnaissance survey of aboveground biomass of the understory was made in stands of five forest types in southwestern Nova Scotia. In most types, seedlings of arboreal species, mostly conifers, constituted about half the biomass. Mosses contributed the greatest share of the biomass of non-woody plants. Ferns were the most important herbaceous group. Total understory biomass was above the average of other reported studies, possibly as a result of less overstory biomass.
Natural interspecific hybridization between sexual and apogamous species of the beech fern genus Phegopteris Fée
Authors: Mulligan Gerald A. , Cinq-Mars Lionel , Cody William J.
Published: September 2008

A clone of beech fern found growing on a mountain near Rougemont in Rouville County of Quebec is shown to be a natural hybrid between two species of Phegopteris that grow together at that location, the circumboreal species P. polypodioides Fée and a species endemic to eastern North America, P. hexagonoptera (Michx.) Fée. Phegopteris polypodioides is shown to be an apogamous triploid (2n = 90), P. hexagonoptera a sexual diploid (2n = 60), and the interspecific hybrid between these two species an apogamous tetraploid (2n = 120). It was concluded that the natural hybrid was produced by the union of a motile gamete, containing 90 chromosomes, from an antheridium on a prothallus of apogamous P. polypodioides with a female gamete, containing 30 chromosomes, on a prothallus of sexual P. hexagonoptera. This is the second report of interspecific hybridization between sexual and apogamous species of ferns. The morphology of both parents and the hybrid supports the conclusion that the apogamous species contributed more genetic material to the hybrid than did the sexual species. It is suggested that this hybrid probably occurs at other locations where the ranges of P. polypodioides and P. hexagonoptera overlap.
Organ culture with black cottonwood: morphogenetic response of female catkin primordia
Authors: Bawa K. S. , Stettler R. F.
Published: September 2008

Female catkin primordia of black cottonwood (Populus trichocarpa T. & G. ex Hook.) were cultured for 70 days on a modified Murashige and Skoog's (1962) medium in vitro. Explants 2–3 mm long, and with bud scales removed, gave the best results, many of them developing floral structures characteristic of the female sex. There was a general tendency to callus formation with increasing age of the culture, occasionally followed by a reversal to vegetative growth. Catkin primordia raised on Wolter's medium without auxin or kinetin, but with 6-benzylaminopurine, and at 250 ft-c for a 16-h photoperiod, proliferated axillary shoots in loco of pistils.
Growth kinetics of Marquis wheat. III. Nitrogen dependence
Authors: Macdowall F. D. H.
Published: September 2008

The growth coefficients, k′1, of whole plants and their parts were obtained by kinetic analysis of primary data on growth in nutrient solutions that differed only in the concentration 1.7, 8.4, 42, 210, or 1050 ppm nitrogen (N), each at about five different light intensities (I) from 300 to 3600 ft-c. Maximal values kmL and kmN were computed for nonlimiting levels; and, efficiencies (1/K)L and (1/K)N were computed for vanishingly low levels of light and nitrogen. The growth coefficients of the leaves or other organs were not preferentially affected by the N supply, but “stem” growth still dominated at saturating levels of N and I. The influence of N on growth was greatest at high I and vice-versa, by hyperbolic dependencies. Computations of maxima, as kmL.N, from these saturation curves yielded a value of 0.36 per day for whole plants, and this may be close to the genetically determined absolute maximum value. Plant growth in 1.7 and 8.4 ppm N was nearly saturated by 3600 ft-c I, but the growth of plants in nonlimiting N supply was only 70% saturated by that light intensity. Nitrogen at 1050 ppm saturated plant growth at all I including 3600 ft-c, when k′1 = kmn, and also at saturating I, when kmL = kmL.N. At and below 2200 ft-c I plant growth was saturated by only 42 ppm N, and growth at 300 ft-c I was virtually independent of N from the nutrient solutions. At nonlimiting I plant growth was halved by only about 12 ppm N; and this, as 50% nitrogen stress “NS50,” is proposed as a useful criterion. Light and nitrate N were most efficiently used for growth at the sites of their absorption. Roots were 41% less efficient than laminae in the use of photosynthate at nonlimiting I, and laminae used N 50% less efficiently than roots at nonlimiting N. These priorities might be considered as primary morphogenic effects of these environmental factors, effects whose identification is difficult with growth coefficients and impossible by secondary "growth analysis." At 1.7 ppm nutrient N, chlorophyll was subject to net photobleaching after 3 weeks growth. The perturbing effect of the removal of half-used endosperm was reflected in halved plant size but the growth coefficient was not decreased, an observation of consequence to literature on growth effects.
A new diploid species of Lotus (Leguminosae) in Pakistan
Authors: Sz.-Borsos Olga , Somaroo B. H. , Grant William F.
Published: September 2008

Seed was received as Lotus corniculatus L. var. minor Bak. from Dr. B. L. Burtt of the Royal Botanic Garden, Edinburgh, who collected them from plants growing in Peshawar, Pakistan. Plants grown from this Peshawar seed all have a somatic chromosome number of 12. Measurement made on 15 phenotypic characters have been compared with six other diploid species of Lotus. From these analyses and a survey of the literature, it has been determined that these plants do not match any known diploid species, or variety, and are probably of the same taxon that Baker described as L. corniculatus L. var. minor. It is considered that this diploid taxon was incorrectly associated with the tetraploid species L. corniculatus L. s. str. (2n = 24). From a study of its nomenclature and the fact that the varietal description by Baker is too poor for the characterization of a species, the plants grown from the Peshawar seed have been described as a new species and named Lotus burttii Sz.-Borsos after Dr. B. L. Burtt, who collected this material. While its occurrence is so far not known outside of Pakistan, its complete area of distribution remains to be investigated.
An ecological study of grasslands in Banff, Jasper, and Waterton Lakes National Parks
Authors: Stringer P. W.
Published: September 2008

Seventy-one stands were sampled as representative of the grasslands at low elevations in Banff, Jasper, and Waterton Lakes National Parks. Quantitative methods were used to describe the floristic composition and vegetation structure of these grasslands and some of the physical and biotic environmental factors operating on them.Three-dimensional ordination based on vegetative similarity detected correlations between the grassland composition and structure and the measured environmental factors; indicated a discontinuity between the Waterton and Banff–Jasper stands; and suggested several grassland types.Cluster analysis verified this discontinuity and clarified the classification of the 71 stands.The two most extensive grassland types were mesophytic Festuca – Danthonia Prairie in Waterton Park, characterized by a high species diversity and by the dominance of Danthonia parryi, Festuca idahoensis, F. scabrella, Galium boreale, and Lupinus sericeus; xerophytic Koeleria – Calamagrostis montanensis Grassland, most prominent in the Athabasca River valley in Jasper, and characterized by low species diversity, by the dominance of Calamagrostis montanensis, Koeleria cristata, Antennaria nitida/rosea, Artemisia frigida, and Astragalus striatus and by heavy grazing by elk. Less distinct types were low-lying grass and sedge meadows in Waterton, Poa – Hordeum jabatum Grasslands, Koeleria – Geum triflorum Grasslands, Stipa richardsonii Shrub Savanna, and Elymus innovatus Shrub Savanna.
Fatty acid composition of lipids in various plant cell cultures
Authors: Tattrie N. H. , Veliky I. A.
Published: September 2008

The total fatty acids of cultured cells from 11 cell lines (nine species of plants) were determined. Linoleic acid was the most abundant fatty acid in most of the cultures (16.3%–60.9%, average = 39.4%). Palmitic acid varied from 19.1% to 54.8%, average = 28.4%. Stearic and oleic acids were usually less than 10%, with averages of 7.4% and 4.7% respectively. Linolenic acid varied from 3.5% to 19.8% in nine of the cell lines but morning glory (Ipomoea sp.) and soybean (Glycine max) contained 35.7% and 51.2% respectively. Arachidic acid was either absent or present in amounts of less than 5%.The total fatty acid patterns of various parts of Ipomoea sp. and Glycine max plants were compared with those of the cultured plant cells. The fatty acid composition of the leaves and of the cultured cells were quite similar in both plants. The lipids found in tissue culture cells are not necessarily comparable to those of the part of the intact plant from which the cell culture was established.
Morphology of bacilliform particles associated with raspberry vein chlorosis virus
Authors: Stace-Smith Richard , Lo Esther
Published: September 2008

Bacilliform particles were found in thin sections of leaves from raspberry (Rubus idaeus L.) infected with raspberry vein chlorosis virus. Similar particles were not found in leaf tissue from a healthy raspberry plant or from a plant infected with raspberry mosaic virus. The bacilliform particles were detected in parenchyma cells within the vascular bundle or mesophyll cells near the vascular bundle. The particles were restricted to the cytoplasm and occurred singly or in bundles of from 2 to 14 parallel particles enclosed within a vesicle. particles were rounded at both ends. the mean dimensions of 42 particles were 506 × 83 nm (ranges: 442 to 560 nm and 73 to 91 nm). in cross section, the particles had three concentric layers, with average diameters of 83 nm, 53 nm, and 23 nm. the wall of each layer was about 70 Å thick and the middle layer showed regular surface striations with a periodicity of 50–55 Å.
Diversity, richness, and evenness during a primary sand dune succession at Grand Bend, Ontario
Authors: Morrison R. G. , Yarranton G. A.
Published: September 2008

Asymptotic increases in diversity, richness, and evenness are reported from a primary sand dune succession. Rapid increases in diversity and evenness were observed in the first 1000 years of the 4800 sampled; richness appears to increase little after 2000 years of succession.
Chemotaxonomic studies on Dryopteris from Quebec and eastern North America
Authors: Britton Donald M. , Widén Carl-Johan
Published: September 2008

Chromatographic analyses of the phloroglucinol derivatives in 213 collections of Dryopteris from eastern North America and particularly Quebec were made. The taxa studied were two diploid species, D. assimilis S. Walker and D. intermedia (Muhl.) A. Gray; two tetraploids, D. spinulosa Watt and D. campyloptera Clarkson; the triploid hybrid, D. × triploidea Wherry; all in the D. spinulosa complex. Also studied were the tetraploid species D. cristata (L.) Gray, the triploid hybrid, D. × boollii (Tuckerm.) Underwood, the tetraploid species, D. filix-mas (L.) Schott, and the diploid D. marginalis (L.) A. Gray. Both glandular and glabrous specimens of D. assimilis and D. campyloptera were studied, but it was found that these characteristics were not necessarily correlated with the presence or absence of phloroglucinols. Dryopteris campyloptera consists of plants which may be "phloroglucinol rich" or "phloroglucinol poor," while D. assimilis and D. spinulosa are both low in phloroglucinol content as compared to European plants. The geographical ranges of the species is briefly considered and the chemical uniformity of some taxa and the variability of others is discussed.
Antialgal activity of chloroplatinic acid on Chlamydomonas eugametos
Authors: Nakamura K. , Hepler W. L. , Shaskin E. J. , Brooks D. W.
Published: September 2008

The effect of chloroplatinic acid on the growth of the unicellular green alga Chlamydomonas eugametos has been studied. This platinum compound reduces the rate of cell division and induces palmelloid formation by preventing the liberation of dividing cells. Recovery from the chloroplatinic-acid effect occurs after removal of the compound from the medium.
Germination and survival in a population of the winter annual Alyssum alyssoides
Authors: Baskin Jerry M. , Baskin Carol C.
Published: September 2008

Alyssum alyssoides L. is an Eurasian winter annual that has become naturalized in the United States, where it grows in bare, disturbed habitats. In north-central Kentucky seeds germinate during summer and early autumn, and plants overwinter as semirosettes. Flowering and seed production occur in spring, and mature seeds are dispersed in late spring and early summer. At maturity seeds are conditionally dormant, but by early summer to midsummer they are capable of rapid germination in light and darkness at temperatures that occur in the habitat. Unlike other species of winter annuals from the same geographic area, seeds of A. alyssoides can germinate rapidly and to high percentages at field temperatures in July and August when the soil is sufficiently moist for a few days. However, plants from summer-germinating seeds are killed by droughts during July and August, and all plants that survive to maturity are from autumn-germinating seeds. On the basis of its germination characteristics and drought intolerance, A. alyssoides is not well adapted to a warm, temperate climate with summer rainfall interspersed with periods of drought such as occurs throughout much of the southeastern United States. This may help to explain why the species has not been reported from states south of Kentucky in the eastern United States.
Carpelloids on tobacco stamen primordia in vitro
Authors: Hicks Gary S.
Published: September 2008

Premeiotic stamen primordia of tobacco were cultured for 6 weeks on liquid media supplemented with sucrose and kinetin. On 1.0 ppm kinetin, organoids and carpelloid outgrowths arose on the anthers, but not at [Formula: see text] this level of kinetin. The frequency of carpelloids is also governed by sugar concentration in the medium.
Acrylamide gel electrophoresis of proteins from intact and cultured plant tissues
Authors: Ibrahim R. K. , Cavia Emil
Published: September 2008

An improved method is described for the extraction of soluble proteins from intact and in-vitro-cultured plant tissues. Its main characteristics are the elimination of contaminants, concentration and stability of extracts, and suitability for acrylamide gel electrophoresis. The usefulness of the method was demonstrated by depicting the differences in protein complements of intact cotyledons, callus tissue, and cell suspension cultures of flax.
A generic revision of Portulacaceae tribe Montieae using techniques of numerical taxonomy
Authors: McNeill J.
Published: September 2008

Using a variety of clustering and ordination techniques on data from 37 species or species complexes recognized within the Portulacaceae tribe Montieae, a classification is proposed in which two genera, Claytonia and Montia, are recognized. Claytonia is distinguished from Montia by the possession of a basal leaf rosette, a scape-like stem with a pair of opposite leaves, and tricolpate pollen; this circumscription agrees with that originally proposed by Greene in 1891 and endorsed by Swanson (1966) in his review of relationships in the group; it differs, however, from that adopted in most recent Floras in that it includes the annual Limnia group in Claytonia. Within Claytonia, four sections are recognized, while nine are distinguished within the more variable Montia; the latter correspond to the segregate genera recently adopted by Nilsson and Yurtsev. A taxonomic synopsis is given of the genera, sections, and species, with keys to the genera and sections recognized. Three new combinations at sectional level (Montia sections Mona, Claytoniella, and Maxia), one at species level (Montia vassilievii), and two new varietal names are proposed.
Distribution of label from 3H-glucose and 3H-leucine in lettuce cotyledons during the early stages of infection with Bremia lactucae
Authors: Andrews John H.
Published: September 2008

Light and electron microscope autoradiography were used to study the distribution of label from 3H-glucose and 3H-leucine in lettuce cotyledons that had been supplied either labelled compound through their petioles before inoculation with Bremia lactucae Regel. The distribution and intensity of label in the fungus and host have been analyzed statistically. The pathogen accumulated label from 3H-glucose before penetration and thereafter. During the early stages of infection there was virtually no label from 3H-leucine in fungal structures. However, at 14 and 16 h after inoculation, intercellular hyphae and haustoria were heavily labelled. More glucose than leucine was exuded onto epidermal surfaces and inoculum droplets on cotyledons supplied with 3H-glucose were about 10-fold more radioactive than those on cotyledons supplied with 3H-leucine. When either labelled compound was added in the inoculum drop to non-radioactive cotyledons, the fungus but not the host accumulated tritium. Both labelled substances were metabolized by the spores when germinated in isolation.
Nature of the guard cell wall in leaf stomata of three Ophioglossum species
Authors: Peterson R. L. , Firminger M. S. , Dobrindt L. A.
Published: September 2008

A β-1,3-glucan which has characteristics of callose was identified as a component of the cell wall in stomatal guard cells in three species of the fern, Ophioglossum. This identification was made by the fluorochrome properties of callose when stained with aqueous solutions of aniline blue. Controls involved both the effect of solutions of different pH on autofluorescence of guard cell walls and the extraction of leaf tissues with β-1,3-glucanases before staining with aniline blue. An electron-translucent region between the plasmalemma and the cell wall proper was observed with the electron microscope and corresponded in position with the areas that fluoresced after aniline blue staining.Other components of the guard cell wall identified included cellulose, which was identified by staining techniques, polarization microscopy, and electron microscopy; and a phenolic substance identified by a number of staining reactions. The cell wall failed to stain with a number of reagents for the identification of lignin.
Systematics of Conidiobolus (Entomophthorales) using numerical taxonomy. I. Biology and cluster analysis
Authors: King Douglas S.
Published: September 2008

The morphology and taxonomic history of the genus is reviewed. In field studies, substrates yielding isolates of Conidiobolus were varied, and success in obtaining isolates appeared to be correlated with high moisture. Conidiobolus coronatus was very abundant. Isolates of this fungus varied greatly in abundance of villose resting spores and 14 did not produce microconidia. Ranges in diameters of microconidia and primary conidia were greater than previously described. Thick walls developed in conidia from the field isolates projected onto Petri-dish lids. This phenomenon could be a means for surviving unfavorable conditions. Morphological examinations were performed on 17 type specimens of Conidiobolus species, and on cultures representing 36 of the named taxa after obtaining single-spore isolates. The ability to produce various spore types was readily lost in culture. The primary conidia of all type cultures were determined to be multinucleate. Optical density at 725 nm and dry weight of known packed cell concentrations were measured and found to have a linear relationship. Utilization of five nitrogen sources and four carbon sources was determined for the type cultures by using optical density. Cluster analysis of the named taxa was done using NTSYS, based on morphological and nutritional characters.
Changes in the amount and composition of fractions from extracellular polysaccharide during the culture cycle of cotyledon cell suspension culture of bush bean (Phaseolus vulgaris cv. Contender)
Authors: Mante S. , Boll W. G.
Published: September 2008

Three different polysaccharides (cold-water-soluble pectin, EDTA-soluble pectin, and neutral polysaccharides) were separated from extracellular polysaccharide produced by bush-bean cotyledon suspension cultures. The different polysaccharides were associated with different phases of the culture cycle. The neutral sugars present in the pectin fractions showed considerable fluctuation during the culture cycle as compared with the rather small changes in the levels of the sugars present in the neutral polysaccharides.
The relationship of tissue chlorogenic acid concentrations and leaching of phenolics from sunflowers grown under varying phosphate nutrient conditions
Authors: Koeppe D. E. , Southwick L. M. , Bittell J. E.
Published: September 2008

A large increase in the concentration of the isomers of chlorogenic acid was observed in extracts of sunflowers grown under phosphate-deficient conditions when compared with phosphate-sufficient plants. More phenolic compounds were leached from living intact roots, dried roots, and tops of phosphate-deficient plants than from phosphate-sufficient ones. These leachates did not contain any of the isomers of chlorogenic acid or caffeic acid but did contain scopolin. The influence of phosphate deficiency on polyphenol concentrations in plants and their possible role in allelopathic interactions between plants are discussed.
Ultrastructural changes in the cell surface of Coelomomyces punctatus infecting mosquito larvae
Authors: Powell Martha J.
Published: September 2008

As the fungus Coelomomyces punctatus develops in the coelomic cavity of the mosquito Anopheles quadrimaculatus, the conformation of the plasma membrane and extracellular coat of the fungus changes markedly. The vegetative stage was surrounded by a granular and fibrillar extracellular coat which reacted positively in the silver methenamine procedure for the localization of polysaccharides. Numerous simple, branched or contorted cytoplasmic protuberances covered the irregularly shaped hyphal bodies. The surface of the hyphal body adjacent to the fat body of the mosquito had occasional involutions of the plasma membrane sheathed by cisternae of endoplasmic reticulum. In contrast with these hyphal bodies, cytoplasmic protuberances were spaced at wide intervals along filamentous hyphae. Aborting thalli were contorted and deeply lobed. The plasma membrane was smooth, and cytoplasmic protuberances were absent on other hyphae and hyphal bodies, particularly at advanced stages of infection. Instead unattached vesicles, morphologically similar to the protuberances found on some thalli, were embedded in granular material clustered around the smooth plasma membrane of these thalli. Mosquito hemocytes appeared to engulf these vesicles and granular material. As the vegetative stage was transformed into the reproductive stage, a newly formed, compact extracellular layer surrounded the sporangial initial. Later, a darkly staining wall appeared around the resting sporangium. Cisternae of endoplasmic reticulum consistently subtended thin areas in this pitted wall.