bluuebunny/crossref_metadata_2025 huggingface dataset:
Load Redistribution on Lead Screw Threads Wearing Under Varying Operating Conditions
Authors: Murphy David J. , Blanchet Thierry A.
Published: August 2008

The load applied to a lead screw assembly is distributed amongst the engaged threads of its wearing nut in a manner that can range from highly nonuniform to nearly uniform. Nonuniform load distributions can arise when new or unworn threads are initially placed into service or, alternatively, in worn threads whereupon the operating conditions are changed from pre-existing conditions at steady-state wear. In threads wearing under constant conditions, nonuniform load distributions evolve to uniform load distributions with sufficient continued sliding as the most heavily loaded threads wear most rapidly, causing their loads to be redistributed to those threads less heavily loaded. Using a newly implemented discrete-thread numerical approach, an example lead screw with rigid nut and elastic screw body having flexible meshed thread pairs is modeled here to demonstrate the broad distribution of thread loads on a new lead screw assembly that gradually evolves toward uniformity as the coupled consideration of thread loading and wear depth approaches a steady-state of equal rates of thread wear. Thread load redistributions brought about by linear ramp changes in applied load, or temperature in the case of a nut/screw pair of dissimilar materials, are predicted at various rates of ramp between prior and future steady operating conditions. While showing the expected maintenance of uniform thread loading under slowly ramped conditions, this numerical approach was verified in cases of rapid ramps approaching step changes, for which existing closed-form analytical models provide agreement. At intermediate rates, this numerical model is complemented by newly expanded closed-form analytical models of both discrete- and continuous-thread types that describe asymptotic behavior during extended ramps.
Contact Pressure of Indented Wide Elliptical Contacts: Dry and Lubricated Cases
Authors: Biboulet N. , Lubrecht A. A. , Houpert L.
Published: August 2008

Indents perturb the pressure and stress distribution and increase the failure risk of rolling element bearings. A numerical study of the pressure perturbation is proposed. An existing dry contact model is extended to account for the indent shoulder influence and the pressure collapse in deeper indents. Moreover, results for pure rolling lubricated contacts are presented. Finally, the ellipticity influence is studied for both dry and lubricated contacts.
Air Bearing Interface Characteristics of Opposed Asymmetric Recording Head Sliders Flying on a 1 in. Titanium Foil Disk
Authors: White James
Published: August 2008

The current effort was motivated by the increasing appearance of data storage devices in small portable and mobile product formats and the need for these devices to deliver high storage capacity, low power requirements, and increased ruggedness. In order to address these requirements, this work considered the storage device to utilize a 1 in. titanium foil disk and a pair of opposed femtosized zero-load recording head sliders with asymmetrically configured air bearing surfaces. A titanium foil disk, due to its reduced thickness and relatively low mass density, requires less operational energy than a hard disk while providing storage densities and data transfer rates typical of a hard disk. The zero-load sliders were chosen in order to make negligible the air bearing interface normal force acting on the disk surface that can lead to high speed disk instability. The asymmetry of the slider air bearing surfaces, together with the disk dynamic flexibility, greatly improves the ability of the slider-disk interface to absorb substantial mechanical shock and other dynamic effects without the associated contact and impact typically observed with a hard disk. The current project evaluated the characteristics of this slider-disk air bearing interface for both static and unsteady operating conditions. Time dependent studies included a numerical simulation of the dynamic load process and the response to mechanical shock. A comparison with the performance of a hard disk interface was also included.
Carbon-Fiber Reinforced Paper-Based Friction Material: Study on Friction Stability as a Function of Operating Variables
Authors: Fei Jie , Li He-Jun , Qi Le-Hua , Fu Ye-Wei , Li Xin-Tao
Published: August 2008

Carbon-fiber-reinforced paper-based friction material (CFRPF), as a new type of wet friction material for automatic transmission, was prepared by a paper-making process. The frictional response of CFRPF is highly complex under a set of dynamically variable operating conditions. To better understand the effect of operating factors (braking pressure, rotating speed, oil temperature, and oil flow rate) on friction stability of the material, tests were carried out using a single ingredient experiment and the Taguchi method. Experimental results show that the braking stability and the dynamic friction coefficient (μd) decrease as braking pressure, rotating speed, oil temperature, and oil flow rate increase. The influence of braking pressure on μd is largest among the four operating factors. μd declines gradually during the first 3000 repeated braking cycles and changes very little subsequently due to the surface topography change in friction material.
ISOLATION FROM WHEY OF INHIBITORS OF THE BARLEY STRIPE MOSAIC VIRUS
Authors: Hagborg W. A. F. , Chopra N. M. , Chelack W. S.
Published: August 2008

Attempts were made to isolate the substance or substances in whey responsible for the inhibition of infection with the barley stripe mosaic virus (BSMV). The fractions isolated were bioassayed to determine their potency. The bioassay method is described. Paper electrophoresis was used to indicate the composition of the fractions.Potent proteinaceous substances were obtained by dialysis, selective denaturation with ethanol, and fractional precipitation with ammonium sulphate. A progressive increase in potency was associated with an increase in the proportion of material that moved towards the cathode in electrophoresis at pH 8.6.Elutions from the electrophoretic bands gave evidence of very high potency in the two substances that moved towards the cathode but there was also evidence of degradation during elution. Quantitative bioassays of eluted materials were uncertain because of indications that the eluant had dissolved something from the paper.Development of electropherograms with Solway purple had no derogatory effect on the inhibitory material but ninhydrin destroyed all activity.
DEVELOPMENT OF THE EMBRYO OF MEDICAGO SATIVA L. AFTER NORMAL FERTILIZATION AND AFTER POLLINATION BY OTHER SPECIES OF MEDICAGO
Authors: Fridriksson Sturla , Bolton J. L.
Published: August 2008

The embryonic development of diploid and tetraploid Medicago sativa from the formation of the zygote to mature seed is described and illustrated. The embryo reaches the global stage at 7 to 8 days; the heart stage at 11 to 13 days; and the torpedo stage at 14 to 16 days after pollination. Full size is attained at about 25 days but food reserves apparently continue to be stored and maturity may not be reached until about the 35th day.Pollination of M. sativa stigmas with pollen from highly incompatible species failed to produce mature embryos. Crosses involving M. lupulina produced no sign of embryo development. However, when M. arborea, M. blancheana, M. marina, M. platycarpos, M. rigidula, M. ruthenica, or M. scutellata was used as a pollen parent the early stages of embryonic growth were initiated.
GLYCOLIC ACID OXIDASE AND FUSARIOSE WILT OF TOMATOES
Authors: Sanwal B. D. , Waygood E. R.
Published: August 2008

When roots of tomato plants are infected with Fusarium, systemic changes are induced in the activities of glycolic acid oxidase and glyoxylic reductase of the leaves. A marked decrease in glycolic acid oxidase activity is apparent 8–16 days after inoculation when the leaves show chlorotic symptoms. The depressed activity of this enzyme is due to a general decrease in the concentration of its flavin coenzyme, FMN. Both FMN and FAD begin to decrease after 8 days. On the other hand glyoxylic acid reductase shows an increased activity 20 days after infection. These alterations in enzymic activity result in a twofold accumulation of glycolic acid 20 days after infection even though the fungus is never present in the leaves.
ROOT PRODUCTION AND THE ESTIMATION OF NET PRODUCTIVITY
Authors: Bray J. R.
Published: August 2008

Data on the net production of oven-dry organic matter from 28 temperate angiosperm herbaceous species and 4 temperate arboreal species were analyzed to determine the relationship between below-ground and above-ground yearly increment. Mean yearly net herbaceous production (t/ha) was 3.9 for below-ground parts, 5.9 for above-ground parts, and 9.8 total. Mean yearly net arboreal production (t/ha) was 1.9 for below-ground parts, 8.9 for above-ground parts, and 10.8 total.The mean below-ground/above-ground ratio and mean below-ground production was significantly higher for herbaceous species. Mean above-ground production was significantly higher for arboreal species. There was no significant difference between total herbaceous and total arboreal production. Productivity comparisons based only upon above-ground parts are likely to be biased in favor of arboreal species.In herbaceous species, root production decreased with age and increased from fruit crops to root and tuber crops and the below-ground/above-ground ratio increased from moist to mesic to xeric species. Arboreal species were uniform in below-ground/above-ground ratios.
CYTOTAXONOMY OF CIRSIUM MUTICUM, CIRSIUM DISCOLOR, AND CIRSIUM ALTISSIMUM
Authors: Frankton C. , Moore R. J.
Published: August 2008

Morphological descriptions, chromosome numbers, and Canadian distribution of Cirsium muticum and C. discolor are given. The related species C. altissimum of the United States is similarly considered. The chromosome numbers of the species are: C. muticum, 2n = 20; C. discolor, 2n = 20; C. altissimum, 2n = 18. Extra chromosomes, possibly to be considered as accessories, were found in C. muticum and C. discolor. A Florida collection of C. muticum had the apparently triploid number 2n = 30. The morphological and cytological evolution of the group is discussed.
FORMATION AND FUNCTION OF SOLUBLE PROTEINS IN GHLOROPLASTS
Authors: Smillie Robert M.
Published: August 2008

not available
PHOTOSYNTHESIS AND METABOLISM OF MARINE ALGAE: V. RESPIRATION AND METABOLISM OF C14-LABELLED GLUCOSE AND ORGANIC ACIDS SUPPLIED TO FUCUS VESICULOSUS
Authors: Bldwell R. G. S. , Ghosh N. R.
Published: August 2008

Fronds of F. vesiculosus were supplied with glucose-UL-C14, pyruvate-2-C14, acetate-1-C14, acetate-2-C14, or formate-C14, the acids being presented as the sodium salts. The radioactivity of various fractions of the fronds as well as respired CO2was determined after various times, and the distribution of radioactivity among the compounds present in the alcohol extract was determined. The contribution of glucose to respired CO2was much less than that of the organic acids. However, although its uptake and metabolism were less, a large proportion of the glucose that was metabolized was converted to CO2. Glucose contributed somewhat to polysaccharides, but the organic acids were much better precursors of alginic acid. The pattern of labelling among soluble compounds, of which glycerol was especially prominent, indicated that several pathways of metabolism operated, involving both carboxylation and decarboxylation reactions.
EVIDENCE FOR INDOLE-3-ACETIC ACID IN BALSAM FIR, ABIES BALSAMEA (L.) MILL.
Authors: Clark J. , Bonga J. M.
Published: August 2008

An ether-extractable auxin was discovered in the inner bark of balsam fir. Characterization of the auxin by paper chromatography, Avena bioassay, and chromogenic tests indicates that it is indole-3-acetic acid. A strong growth inhibitor was extracted together with the auxin.
ON THE HAIRS AND CUTICLE OF LABRADOR TEA LEAVES. A DEVELOPMENTAL STUDY
Authors: Sifton H. B.
Published: August 2008

Developing buds of Ledum groenlandicum Oeder. are studied. By the latter part of May, those that will produce next year's leaves are well advanced, and a month later beginnings of epidermal hairs are present on the leaves. The morphological development of the hairs is traced. Elongate hairs, both multicellular and unicellular, have long, cylindrical, or semicylindrical, vacuolate cells. The elongating cells have a transverse orientation of the cellulose microfibrils in their primary walls as demonstrated by the polarizing microscope. The vacuolate cells of capitate hairs do not become cylindrical, and they lack the regular orientation of the cellulose in their walls. The pectic material does not become calcified, and the hardening of this part of the wall is thus eliminated as a factor in shape control. The abscission of hairs from the upper leaf surface is brought about by a softening of the middle lamella, apparently through a change from pectic acid to soluble pectin rather than by depolymerization. The hairs on the lower surface remain attached, but the walls of their basal cells become cutinized and the hairs are thus isolated from the leaf tissues. An incipient cuticle covers the young leaves in buds collected in November. At this time the linking together of molecules to form cutin has begun, as indicated by the insolubility of the layer in fat solvents, but the bonds must be few, the layer being easily broken down by a solution of sodium hydroxide. The gradually increasing difficulty in bringing about this reaction indicates that, except during the cold of winter, there is a gradual increase in the bonding until late May or early June, when the cuticle is fully formed. Additional evidence was found for the hypothesis that the developing cuticle exerts a deciding influence on the shape of epidermal cells.
ON CHLOROPHYLL TURNOVER IN MONOCOTYLEDONS AND DICOTYLEDONS
Authors: Perkins Harold J. , Roberts D. W. A.
Published: August 2008

Sodium acetate-1-C14 or (in one case) succinic-2,3-C14 acid was fed to both immature and mature leaves of four monocotyledons (lily, oats, philodendron, and tradescantia), three dicotyledons (red clover, petunia, geranium), a gymnosperm (spruce), and a pteridophyte (Boston fern). These experiments have indicated that chlorophyll synthesis and thus chlorophyll turnover in the mature leaves of the monocotyledons is very slow or non-existent. On the other hand, considerable amounts of C14 were incorporated into the dihydroporphyrins isolated from the mature leaves of the dicotyledons, the gymnosperm, and the pteridophyte.
A NEW SPECIES OF MARSSONINA ON STRAWBERRY
Authors: Bolton A. T.
Published: August 2008

A fungus isolated from lesions on leaves of Fragaria virginiana collected near Hudson Hope, B.C., was identified as Marssonina sp. The symptoms of the disease were somewhat different from those produced by the Marssonina stage of the strawberry leaf scorch fungus, Diplocarpon earliana (Ell. & Ev.) Wolf. Differences were also observed in temperature requirements for growth and conidia production, pathogenicity, and size and shape of conidia. It is proposed to give this fungus specific rank and name it Marssonina canadensis.
MODERN POLLEN RAIN STUDIES IN EASTERN ONTARIO
Authors: King James E. , Kapp Ronald O.
Published: August 2008

Moss polsters were collected at 15 sites between Toronto and Lake Timagami, Ontario, and at 4 localities in the Lake Timagami area for the purpose of determining the regional pollen rain and its local variations. Pollen percentages of Acer, Quercus, Ambrosia, Chenopodiaceae, Compositae, and Gramineae decrease northward and Picea, Pinus, and Betula increase at the more northerly sites. From the three most northern sites a regional pollen rain was calculated by averaging the percentages from nine pollen spectra. In this area the regional pollen rain is dominated by Picea (15%), Pinus (38%), and Betula (22%). At one site a grain of Ephedra was recovered, apparently carried in by long range drift. The nearest place that it grows naturally is in the southwestern United States. Various pollen trap types were investigated and it was found that all types of moss polsters and some types of decaying stumps (depending on their moisture-holding capacity) were effective in preserving the modern pollen rain.
THE DEVELOPMENTAL MORPHOLOGY OF TWO SPECIES OF MICROASCUS
Authors: Corlett Michael
Published: August 2008

The ontogeny of the perfect stage in Microascus longirostris and M. irigonosporus has been investigated. Sexuality has also been examined in M. longirostris, M. trigonosporus, M. cinereus, and M. doguetii.Results show that all these species are homothallic, and that perithecial formation in M. longirostris and M. trigonosporus follows the general pattern outlined by previous workers. The author has been able to clarify at least three important developmental phases which had either been ignored or insufficiently described by earlier investigators. These are the formation of the perithecial primordium; the development of the sterile hyphae of the centrum; and the structure and nuclear condition of the ascogenous system.
EMBRYOLOGICAL STUDIES IN CANADIAN REPRESENTATIVES OF THE TRIBE RHINANTHEAE, SCROPHULARIACEAE
Authors: Arekal Govindappa D.
Published: August 2008

Descriptions are given of the ovary and ovules, megasporogenesis, embryo sac, endosperm, embryo, and seed coat structure of Euphrasia arctica Lange, Orthocarpus luteus Nutt., and Melampyrum lineare Desr. Although the ovary is usually bicarpellary, syncarpous, and bilocular with axile placentation in the tribe, a tendency toward unilocularity and parietal placentation occurs in Orthocarpus luteus. The number of ovules is reduced to four in Melampyrum lineare. Development of the embryo sac is of the monosporic eight-nucleate type in Euphrasia arctica and Orthocarpus luteus, but is tetrasporic and seven-nucleate in Melampyrum lineare. No fusion of polar nuclei occurs in the latter. The endosperm is ab initio cellular. Nuclear division in the primary micropylar chamber is followed by a vertical wall which remains incomplete. Aggressive haustoria develop at opposite ends of the endosperm. The chalazal haustorium is unicellular and binucleate. The micropylar haustorium is incompletely bicelled, with four nuclei in E. arctica and M. lineare and two nuclei in O. luteus. In M. lineare six to eight tube-like processes develop from the micropylar haustorium of which one usually enlarges and enters the funicle. The endosperm proper is generally uniform in E. arctica and O. luteus, but in M. lineare it becomes differentiated into three regions, the massive micropylar part consisting of cells with thickened, prominently pitted walls and the chalazal part of thin-walled cells with large intercellular spaces. Embryo development in E. arctica and O. luteus resembles that of Capsella bursa-pastoris, while development in M. lineare follows that of Polygonum persicaria. Embryologically Melampyrum lineare differs markedly from other members of the tribe.
DARK FIXATION OF C14-BICARBONATE BY MARINE ALGAE
Authors: Craigie J. S.
Published: August 2008

The ability of several multicellular marine algae to remove NaHC14O3 from seawater in darkness has been compared. Members of the Phaeophyta removed approximately four to eight times more isotope than did members of the Rhodophyta and Chlorophyta examined. After 2 minutes of dark fixation, aspartic and glutamic acids were the main compounds identified in both Fucus vesiculosus and Polysiphonia lanosa. Radioactivity appeared largely in citric plus isocitric acids in Fucus, whereas radioactive organic acids were not detected in Polysiphonia even after 30 minutes. Fractionation of F. vesiculosus after 2 hours of dark fixation showed that 95% of the total radioactivity recovered occurred in the fraction soluble in 70% acetone.Twenty-four hours of darkness immediately prior to a 2-hour dark fixation period reduced the total radioactivity incorporated to almost one-half of the control values. Either artificial seawater (one-fifth natural salinity) or a medium in which NaCl was substituted by KCl had little effect on the total radioactivity fixed during darkness. The distribution of isotope, however, showed some alterations.
TRIPTEROSPORA TETRASPORA SPEC. NOV., A NEW CLEISTOTHECIAL ASCOMYCETE
Authors: Rai J. N. , Mukerji K. G. , Tewari J. P.
Published: August 2008

Tripterospora tetraspora Rai, Mukerji and Tewari spec, nov., a new member of the rare family Tripterosporaceae, has been described from Indian soils (pH 5.7–10.5). This species is characterized by the presence of four-spored asci.
A NEW ACREMONIELLA FROM INDIAN SOILS
Authors: Rai J. N. , Tewari J. P.
Published: August 2008

A new species of Acremoniella Saccardo, isolated from soil (pH 6.8) collected from Pallia, District Kheri, India, is named as A. serpentina Rai and Tewari spec. nov. because of the occurrence of strongly serpentine conidiophores.
SOME EFFECTS OF SMELTER POLLUTION UPON AQUATIC VEGETATION NEAR SUDBURY, ONTARIO
Authors: Gorham Eville , Gordon Alan G.
Published: August 2008

The numbers of submerged and floating macrophyte species present in 29 ponds and lakes are inversely related to dissolved sulphates, concentrations of which rise sharply within about 4 to 5 miles of the smelters. Although pollution often leads to strong acidification, numbers of species are low even where sulphuric acid is almost wholly neutralized, and waters are above pH 6. Because sulphate ions are unlikely to be toxic at the levels encountered, and since pollution also increases the concentration of heavy metals in the waters, it is suggested that these may reach toxic levels near the smelters.Leptodictyum riparium and Eleocharis acicularis v. submersa seem to be most tolerant of smelter pollution, while Utricularia vulgaris and Potamogeton epihydrus v. nuttallii appear rather sensitive to it.
THE PHYTOSOCIOLOGY OF THE DECIDUOUS FORESTS OF EXTREME SOUTHERN ONTARIO
Authors: Maycock Paul F.
Published: August 2008

A phytosociological analysis of the deciduous forest region of extreme southern Ontario is presented. One hundred and thirty-one stands were sampled quantitatively to determine the composition of the tree and sapling strata. A series of environmental characteristics were also measured or were carefully observed where measurement was impractical. The composition of the tree layer was expressed in terms of a series of importance values determined from measures of frequency, density, and dominance or basal area, on a relative basis, with the importance values for all trees in a stand summing to 300. An analysis of the relationship of the quantitative characteristics between all stands indicated the futility of the distinct association or distinct community approach to an understanding of forest ecological relationships in the region. An ordination of stands in relation to site moisture characteristics gave expression to the ecological tolerance of individual tree species and emphasized the continuous characteristics of forest patterns in the vegetational complex of the area.The forests of southern Ontario were related quantitatively to those of southern Wisconsin utilizing an index of regional influence based on overall importance for all tree species, in an attempt to interpret regional patterns within the Deciduous Forest Formation of North America.
CONJUGATION IN TREMELLA MESENTERICA
Authors: Bandoni Robert J.
Published: August 2008

Compatibility tests with 26 single-spore isolates of Tremella mesenterica Fr. suggest that heterothallism in this species is of a modified tetrapolar type. Formation of conjugation tubes apparently requires heterozygosity for a single pair of alleles, A and a, but production of a typical dikaryon is controlled by a series of "B factors". The results indicate that the latter are either multiple alleles or multiple factors. Conjugation appeared to occur between isolates with like B's, but the resultant mycelium was abnormal in form. No conjugation tubes formed when isolates with like A's were paired.
COCHLIOBOLUS SATIVUS: VII. NUTRITIONAL CONTROL OF THE PATHOGENICITY OF SOME AUXOTROPHS TO WHEAT SEEDLINGS
Authors: Tinline R. D.
Published: August 2008

The pathogenicity of some strains of Cochliobolus sativus to wheat seedlings was determined. The strains comprised prototrophic and auxotrophic mutants from a common parent, heterokaryons synthesized from auxotrophs, diploids obtained from heterokaryons, and recombinants selected from a diploid.Prototrophic mutants and auxotrophs requiring thiamine, arginine, and pyridoxine were as pathogenic as the parent. Methionineless and lysineless mutants were non-pathogenic. Evidence that the nutritional requirements of the latter mutants directly controlled their pathogenicity was: (1) two methionineless and two lysineless auxotrophs were uniformly non-pathogenic; (2) heterokaryons synthesized from methionineless and lysineless strains and from two methionineless strains were pathogenic; (3) diploids heterozygous for the requirements were pathogenic; (4) prototrophic recombinants from a diploid were pathogenic but auxotrophic ones were non-pathogenic; (5) a prototrophic mutant of a lysineless auxotroph was pathogenic; and (6) the pathogenicity of the auxotrophs was temporarily restored when the appropriate growth requirements were provided as external supplements to the host. The results are discussed.
THE INCREASE IN CONCENTRATION OF TWO STRAINS OF POTATO VIRUS X IN FLOATING LEAF DISCS
Authors: Willis C. B. , Larson R. H. , Fulton R. W.
Published: August 2008

Increases in concentration of two antigenically similar strains (ringspot and yellow) of potato virus X (PVX) in Nicotiana tabacum L. vars. Samsun and Havana 38 and in Nicotiana rustica L. were determined serologically and by local lesion assay. In discs of inoculated leaf tissue floating on Hoagland's solution the rate of increase was greatest at 16° and 20 °C. In Samsun the optimum temperature for the increase in virus concentration was lower for the yellow strain than the ringspot strain. A close correlation between the assay procedures indicated that, as the temperature increased above the optimum for virus increase, either virus synthesis was being inhibited or virus was being denatured. No differences were found where 8- and 16-hour photoperiods were compared to determine their effect on virus increase at 20 °C. Virus concentrations in Samsun and Havana 38 were similar when determined under similar conditions. Concentrations in N. rustica were appreciably higher. In both Nicotiana species the concentration of the yellow strain at any time after inoculation was lower than that of the ringspot strain.
QUELQUES SOCIÉTÉS OU UNIONS D'ÉPIPHYTES DU SUD DU QUÉBEC
Authors: LeBlanc S. C. Fabius
Published: August 2008

The author has studied the ecology and phytosociology of cryptogamic epiphytes in southern Quebec. A great number of microquadrats were made on roadside trees and in various forest associations. Many trees were studied from the base to the upper part of the trunk. Thirty-one epiphytic societies or unions of bryophytes and lichens are described. The horizontal and vertical distribution of the unions on sample trees are illustrated.
PIGMENTS AND OTHER EXTRACTIVES FROM CARPOPHORES OF AMANITA MUSCARIA
Authors: Talbot Guy , Vining L. C.
Published: August 2008

Carpophores of Amanita muscaria (Fr.) S. F. Gray collected near Saskatoon, Saskatchewan, contained a mixture of orange-red, water-soluble pigments, none of which was identical with muscarufin, the red pigment reported in mushrooms of this species found in Europe. The main substances accompanying the pigments in the aqueous ethanolic extract were identified and the amounts of each estimated. Of these, fumaric and malic acids, glucose, trehalose, and mannitol have been reported in European specimens of the fungus. Gluconic and citric acids have not previously been described from this species. The composition of the lipid and free amino acid reserves was also determined.
GENETIC MARKERS AND LINKAGE RELATIONSHIPS FROM TETRAD DATA IN HYPOMYCES SOLANI f. CUCURBITAE
Authors: Georgopoulos S. G.
Published: August 2008

Ten loci were included in linkage studies with Hypomyces solani f. cucurbitae and the following linkage relationships were recognized: (1) compatibility locus (A/a) to a locus for tolerance to the chlorinated nitrobenzenes (cnb-2); (2) locus for femaleness (c) to the locus for maleness (m); and (3) locus for perithecial color (w) to a locus modifying femaleness (stp-4:). Usually parental ditype and tetratype asci were obtained from the cross ♂ × ♀ but the non-parental ditype ascus was found once. The two loci for sex appear to be separated by the centromere to which they both show close linkage. Centromere linkages have also been detected for the compatibility locus and the locus controlling perithecial color.
THE LIFE CYCLE OF PRASIOLA MERIDIONALIS SETCHELL AND GARDNER
Authors: Cole Kathleen , Akintobi Samuel
Published: August 2008

The life cycle of Prasiola meridionalis is diplohaplontic, consisting of an alternation between morphologically dissimilar sporophytic and gametophytic generations. Mature diploid cells at the apex of the thallus divide meiotically, each producing four haploid cells. Eight pairs of chromosomes were counted at first meiotic prophase. The haploid cells divide mitotically, forming polystromatic, gametophytic tissue which becomes a continuation of the monostromatic, sporophytic, or somatic tissue within the same thallus. Patches of dark green cells, containing potential macrogametes, alternate with patches of very light green color which produce microgametes, forming a mosaic pattern in the gametophytic tissue at the apex of the thallus. Oogamy exists in this species, the spherical macrogamete possessing no flagella. Two or more smaller biflagellate microgametes may approach one macrogamete, but only one unites with it to form the zygote. P. meridionalis reproduces asexually by aplanospores which are formed within the diploid somatic tissue. The new thalli resulting from the germination of aplanospores are morphologically similar to those produced from the zygotes.Cultures of P. meridionalis thalli grow well in modified Provasoli's medium, when maintained at temperatures of 5–8 °C and provided with alternate light and dark periods. Gametes are liberated only when fruiting thalli are first illuminated for 2 hours with fluorescent tubes and then kept in the dark for several hours at temperatures of 3–5 °C.
NEW EVIDENCE FOR THE PRESENCE OF INDOLEACETIC ACID IN TOBACCO
Authors: Sirois J. C.
Published: August 2008

An acidic growth-promoting substance, active in the Avena coleoptile elongation test, was extracted from Resistant Havana 211 cultivar of Nicotiana tabacum L. This substance cochromatographed with indoleacetic acid (IAA) in three different solvent systems used singly, or in combination in two-direction chromatography. Its concentration–activity curve was also identical with that of IAA.Refinements in the purification procedure and the use of N,N-dimethylaminocinnamaldehyde as a spray reagent for the tobacco leaf extracts have made it possible to obtain a typical IAA color reaction at the Rf value of the tobacco growth-promoting substance. These results led to the conclusion that the auxin extracted from the tobacco tissues was IAA.
ELECTRO-OSMOSIS IN NITELLA
Authors: Fensom D. S. , Dainty J.
Published: August 2008

Simultaneous measurements of minute electrical current and water flow through single living cells of Nitella translucens have shown that there is an electro-osmotic transport of the order of 100 moles of water per Faraday in the direction of the positive ion flow. This implies the existence of water-filled charged pores through the plasmalemma and tonoplast of the Nitella cell. The pores available for ion movement are far too few to account for the high water permeability of the cell membranes, and the possible extra turgor pressures which might be produced by an electro-osmotic flow through these pores could not be more than 10−4 atmosphere.
CYTOGEOGRAPHY AND EVOLUTION OF THE DESGHAMPSIA CAESPITOSA COMPLEX
Authors: Kawano Shoichi
Published: August 2008

The chromosome number, karyotype, and morphological variation of plants of the Deschampsia caespitosa complex are reported in this paper. It is shown that the chromosome number of 2n = 26 is most common in typical D. caespitosa (L.) Beauv. But, remembering the basic chromosome number in the Agrostideae, the original basic number of the genus Deschampsia is considered to be x = 7. Thus, a reduction of the chromosome number from 28 to 26 is speculated in this particular group of Deschampsia. The plant from Mt. Albert, Canada, referable to D. caespitosa ssp. littoralis (Reut.) Rchb., has a high chromosome number of 2n = 49. Considering the morphological affinity between D. caespitosa ssp. littoralis and D. alpina Roem. & Schult., as well as their geographical distribution, parallel development of the plants with such high irregular chromosome number is assumed.The karyotype of D. caespitosa s. str. was also investigated. This species has a highly specialized asymmetrical karyotype, viz., K(2n) = 26 = 4 V + 10 J + 12 I.On the basis of cytology, morphology, ecology, and geographical distribution, the phylogenetic relationships within this complex were considered. The littoralis type, having well-developed panicles, large spikelets, three (rarely four) florets, and a preference for wet terrestrial sites, is speculated to be the most basic form in the D. caespitosa complex, even though the type with smaller spikelets, i.e., caespitosa s. str. is at the present time much more abundant. Various other population groups such as D. caespitosa v. parviflora (Thuill.) Coss. & Germ., D. brevifolia R. Br., D. alpina Roem. & Schult., and the species of the bottnica group (including D. beringensis Hultén, D. bottnica (Wahlenb.) Trin., D. congestiformis Booth, D. holciformis F. & C. Presl, D. mackenzieana Raup, D. macrothyrsa Tatewaki et Ohwi, D. obensis Roshev., and D. wibeliana Schur.) are presumed to be more specialized.
SOURCES OF CARBON FOR THE SYNTHESIS OF PROTEIN AMINO ACIDS IN ATTACHED PHOTOSYNTHESIZING WHEAT LEAVES
Authors: Hellebust J. A. , Bidwell R. G. S.
Published: August 2008

Attached, rapidly growing wheat leaves were allowed to photoassimilate C14O2 and C12O2 alternately. Samples of leaves were collected after each period of photosynthesis and were analyzed for amounts and total activities of soluble sugars and amino acids, and protein amino acids. The leaves were also analyzed for protein nitrogen and amounts and total activities of respired carbon. Samples of roots were also collected and the amounts, total activities, and specific activities of their soluble compounds were determined. It was possible to calculate from these data the proportions of carbon entering some protein amino acids which came either from soluble amino acid pools or by a direct route from photosynthate, bypassing the soluble pools. More than half of the carbon entering protein-bound serine and glycine was derived from newly assimilated CO2, while protein glutamic acid, aspartic acid, and alanine derived more of their carbon from the soluble amino acid pools. Analysis of the data from roots indicated that a considerable portion of the carbon translocated from the leaves was derived from newly assimilated CO2. There was some indication that protein turnover took place, but it was concluded that proteins could not have contributed significantly as substrates for respiration in these leaves.
EVIDENCE FOR A POLYMERIC INTERMEDIATE IN CELLULOSE BIOSYNTHESIS
Authors: Mortimer D. C.
Published: August 2008

Most of the radioactive glucose incorporated into the α-cellulose of sugar beet and barley leaves during short-term photosynthesis in C14O2can be removed in a small proportion of weight by digesting the cellulose in hot, dilute trichloroacetic acid solution. This acid-soluble component contains little or no free labelled glucose. The radioactivity resides in a glucosan of sufficiently high degree of polymerization that it readily and irreversibly precipitates from solution. The radioactive glucosan is resistant to acid hydrolysis but is readily hydrolyzed by cellulase.While the total radioactivity in the α-cellulose fraction does not increase significantly after 10 minutes following cessation of C14O2administration, a slow transfer of radioactivity from the acid-soluble component to the acid-insoluble residual cellulose can be measured over a period of several hours. The transfer is hastened by holding the leaves in darkness. Both the initial incorporation and the subsequent transfer are blocked by physical alteration of the leaf structure through grinding or freezing and thawing. These results are interpreted as evidence for the participation of a polymeric glucosan as an intermediate in the biosynthesis of leaf cellulose.
BIOSYNTHESIS OF MANNITOL-C14 FROM C14O2 BY DETACHED LEAVES OF WHITE ASH AND LILAC
Authors: Trip P. , Krotkov G. , Nelson C. D.
Published: August 2008

To find a higher plant suitable for the biosynthesis of mannitol-C14, detached leaves of 20 species were illuminated in the presence of C14O2 and subsequent distribution of C14 among their sugars was determined. Mannitol-C14 was found in 4 species, verbascose-C14 in 3, stachyose-C14 in 9, raffinose-C14 in 16, mellibiose-C14in 2, maltose-C14 in 15, sucrose-C14 in 20, galactose-C14 in 8, glucose-C14 in 17, and fructose-C14 in 12. Syringa vulgaris L. and Fraxinus americana L. were found to be the most suitable plants for the preparation of radioactive mannitol of high specific activity. The yield was 19.6% in Syringa, with specific activity = 38.4 μc/mg, and 8.4% in Fraxinus, with specific activity = 68.5 μc/mg.
PLASTID STRUCTURE, CHLOROPHYLL CONCENTRATION, AND FREE AMINO ACID COMPOSITION OF A CHLOROPHYLL MUTANT OF BARLEY
Authors: Maclachlan Sally , Zalik Saul
Published: August 2008

Biochemical properties and chloroplast fine-structure of a viridis mutant of Gateway barley are described. The mutant was deficient in chlorophyll and carotenoids when young but developed nearly normal levels of pigment with age (a virescens type). Etiolated mutant seedlings were low in protochlorophyll. In the young mutant, chloroplasts were small and irregular in shape and they contained large vesicles but no normal lamellae or grana. The level of free amino acids, particularly of serine, was extremely high. These disturbances were overcome with age. It is suggested that the mutation alters the lipoprotein of lamellar structures in the plastid, and that other effects are consequential.
ECOLOGICAL ASPECTS OF AIR POLLUTION FROM AN IRON-SINTERING PLANT AT WAWA, ONTARIO
Authors: Gordon Alan G. , Gorham Eville
Published: August 2008

At Wawa, in northern Ontario, vegetation has been damaged severely by sulphur dioxide pollution from an iron-sintering plant. Damage is mainly restricted to a narrow strip northeast from the sinter plant, since southwest winds are strongly predominant. It is traceable from the air for at least 20 miles in this direction and is estimated as severe within 11 miles and very severe within 5 miles. Within about 10 miles NE. from the sinter plant ground flora variety declines markedly, from about 20–40 species per 40 square meter quadrat beyond this distance to 0–1 species within 2 miles of the pollution source. At the same time sulphate in lake and pond waters increases greatly, from normal levels of about 0.2–0.3 milliequivalents per liter to more than 0.5 meq/l. within 11 miles NE. and up to 2 meq/l. within 2 miles NE. from the sinter plant. Waters within about 5 miles NE. are strongly acid (pH 3.2–3.8), but are not low in calcium. Soluble sulphate in the surface soil rises sharply within about 4 miles NE. from the pollution source, where, also, soil erosion is very pronounced, though traceable farther out.The phanerogams most tolerant of air pollution are Polygonum cilinode and Sambucus pubens, which are infrequent in the normal forest vegetation. In quadrat studies along a northeast transect, seedlings of pinus strobus were not observed within 30 miles from the sinter plant, while those of Picea glauca, P. mariana, and Populus tremuloides were not recorded within 15 miles.
A CHEMICAL STUDY OF THE CELL WALLS OF JERUSALEM ARTICHOKE TUBER TISSUE UNDER DIFFERENT GROWTH CONDITIONS
Authors: King N. J. , Bayley S. T.
Published: August 2008

Slices of tissue from Jerusalem artichoke tubers were maintained under different growth conditions for periods of between 40 and 60 hours, when they were harvested and the walls isolated. The wall preparations were fractionated into the main polysaccharide components and the contents of uronic acid and sugar residues estimated in these components and in the whole wall preparations. Concentrations of plant hormones, optimal for cell enlargement, caused an increase in the water solubility of the pectic fractions of the walls compared to the situation in the water controls where enlargement was negligible. No differences could be detected in wall composition between ray, pith, and cortex tissue in the tuber. In the presence of plant hormones, tissue enlargement was inhibited by calcium ions for about 30 hours, after which it proceeded at a reduced rate. Such calcium treatment appeared to cause no change in wall deposition or composition. The results are discussed in relation to current ideas concerning the plasticity of primary cell walls.
MORPHOLOGICAL CHANGES INDUCED IN HIRSUTELLA GIGANTEA PETCH BY ETHYLENEDIAMINETETRAACETATE
Authors: Loughheed T. C.
Published: August 2008

The addition of ethylenediaminetetraacetic acid (EDTA) at a level of 6 × 10−5 M to a glucose – yeast extract agar medium inhibits the growth of Hirsutella gigantea. At a concentration of 3 × 10−3 M, the mycelium undergoes a morphological change and yeast-like, single cells are formed. These effects may be attributed to the chelating properties of EDTA since they can be reversed by the addition of the metal ions Mn++, Fe++, or Ca++.
VECTOR AND HOST RELATIONS OF NORTH AMERICAN WHEAT STRIATE MOSAIC VIRUS
Authors: Slykhuis J. T.
Published: August 2008

Wheat striate mosaic virus from wheat in southeastern Saskatchewan was acquired and transmitted by both nymphs and adults of the leafhopper Endria inimica (Say) collected in Ontario. The preinfective period of leafhoppers varied from 4–6 to 22–24 days after they first fed on diseased plants. Records of serial transmission by individual insects varied greatly. Some insects infected most test plants on which they were given 2-day feeds during 20 to 30 days after the preinfective period, but subsequently they transmitted irregularly. Some transmitted virus for only a few days. Others transmitted intermittently for several weeks. None of the insects infected any plants on which they fed later than 72 days after feeding on diseased plants even though some lived another 10 to 20 days. Two of 25 insects became infective after feeds as short as 30 seconds on diseased plants, but the percentages of infective insects increased to more than 90% as acquisition access times were increased to 2 or more days. All insects from some inbred lines became infective after 3 days on diseased plants, but 45% of the descendants of one non-transmitting female failed to become infective. The inoculation threshold period on Ramsey wheat test plants was 15 minutes, but the percentage of test plants infected increased from 15% to 88.8% as the test access times were increased to 4 days. The incubation period of the virus in Ramsey wheat seedlings varied from 6 to more than 28 days.In tests of host reactions, all durum wheat varieties were highly susceptible to the virus. Several of the hard red spring and winter wheat varieties were highly susceptible and a few others were highly resistant or immune, but most were mildly to moderately susceptible. Most varieties of oats and barley and 10 species of wild annual grasses were moderately susceptible. Mild to moderate symptoms also developed on some of the plants in one or more varieties of Zea mays L., Lolium multiflorum Lam., L. perenne L., and Bromus inermis Leyss. Four varieties of rye tested did not develop symptoms, nor did any plants in 13 species of perennial grasses, including Chloris gayana Kunth, which is susceptible to the Australian wheat striate mosaic virus. E. inimica multiplied on wheat and 14 other annual and 21 perennial grass species, many of which are common on the prairies. There was considerable variation in the reactions to the virus of different plants in the variety Ramsey, but there were no inherent variations detected between the virus isolates used for the experiments. The wheat varieties Cappelle-Desprez and Rescue which are highly susceptible to the European type of wheat striate mosaic virus did not become infected with the Canadian isolates tested.Attempts to transmit the European type of wheat striate mosaic virus with E. inimica failed.
TRACHEID SIZE AND RATE OF ANTICLINAL DIVISION IN THE CAMBIUM OF CUPRESSUS
Authors: Bannan M. W.
Published: August 2008

Differences of considerable magnitude occur in the tracheid dimensions of North American species of Cupressus. In general the species in arid regions (C. arizonica, C. glabra, C. forbesii, and C. macnabiana) have smaller cells than the species in more humid localities (C. macrocarpa and C. pygmaea). Minor, in some cases questionably significant, differences in cell size are found at different sites for the same species. Noteworthy interspecific differences exist in the frequency of anticlinal (pseudotransverse) divisions involved in cambial cell multiplication. On the whole, these divisions take place at a faster rate in the species with small cells (C. arizonica, C. macnabiana) than in species with large cells (C. pygmaea). Some general relationships between rate of growth, frequency of pseudotransverse divisions, and cell length are also evident. In the stems of mature trees, maximum cell length is apparently associated with a ring width of approximately 1–1.5 mm. Reduction in ring width is accompanied by a rise in frequency of pseudotransverse division and a slight recession in cell length. Widening of the rings produces no change in the rate of anticlinal division, in relation to linear radial accretion, but cell length declines. The orientation of the partition in pseudotransverse division is usually unidirectional in neighboring cells, but reversals in tilt occur after varied intervals. Duration of the interval between reversals shows an inverse relationship with the frequency of pseudotransverse division.