bluuebunny/crossref_metadata_2025 huggingface dataset:
EFFECT OF RUST INFECTION ON HEXOKINASE ACTIVITY AND CARBOHYDRATE DISSIMILATION IN PRIMARY LEAVES OF WHEAT
Authors: Lunderstädt Jörg
Published: August 2008

The increase in activity of hexokinase occurring in leaves of wheat (Triticum sativum L., variety Little Club) after infection with stem rust (Puccinia graminis (Pers.) f. sp. tritici Erikss. and Henn.) cannot be attributed to activation, or relief of inhibition, by compounds of low molecular weight in the host–parasite complex. The light regime to which plants were subjected after inoculation was found to modify the activity of this enzyme in crude extracts, presumably by affecting the concentration of inhibitory substances. Fractionation of proteinaceous material by gel filtration produced evidence that infection results in qualitative differences of the hexokinase protein: the enzyme preparation obtained from infected leaves differs in its behavior on Sephadex G-100 columns from hexokinase preparations isolated from healthy leaves, approximating the gel filtration properties of rust spore hexokinase. The activity in vitro of invertase, glucohexokinase, and fructohexokinase was found to be correlated with the concentration of their respective substrates in the host–parasite complex: after infection, a small increase of endogenous substrate concentration was accompanied by a small increase of the enzyme activity in vitro; and vice versa. Measurements of invertase activity in vitro indicated, and feeding of sucrose-U-14C to detached leaves confirmed, that sucrose dissimilation is increased after infection with rust. As measured in crude enzyme preparations, the postinfectional increase of invertase activity was always larger than that of either glucohexokinase or fructohexokinase. These results support the view that the increase in invertase activity is an important postinfectional lesion in the carbohydrate dissimilation. Metabolic products of sucrose-U-14C in the host–parasite complex included mannitol and trehalose. The biosynthesis of these products is discussed in regard to the overall changes in carbohydrate metabolism of the leaf after infection with rust.
APICAL GROWTH OF POPULUS SPP.: II. RELATIVE GROWTH POTENTIAL OF APICAL AND LATERAL BUDS
Authors: Maini J. S.
Published: August 2008

Populus tremuloides Michx. (trembling aspen) commonly regenerates by formation of suckers (adventitious shoots arising from roots). After decapitation, height increment of aspen suckers dependson the growth potential of the remaining axillary buds that form dominant shoots. The growth potential of lateral buds on the stem of aspen suckers is related to the length of the buds and some lateral buds have a growth potential greater than that of the apical. Decapitation of suckers was not detrimental to their subsequent height increment and in some cases height increment of the decapitated suckers was even greater than that of intact suckers. Decapitation also extended the growth period of suckers.
GENETICS OF PHYTOPATHOGENIC FUNGI: PECTOLYTIC ENZYMES OF VIRULENT AND AVIRULENT STRAINS OF THREE PHYTOPATHOGENIC PENICILLIA
Authors: Garber E. D. , Beraha L.
Published: August 2008

Culture filtrates from a virulent and an avirulent strain of each of three phytopathogenic species of Penicillium grown in a defined medium to which were added different sources of organic carbon had endopolygalacturonase (endoPG) and exopolygalacturonase (exoPG), but neither detectable pectin methylesterase nor pectin lyase activity. Extracts from diseased tissue of oranges inoculated with P. italicum or P. digitatum and from diseased tissue of apples inoculated with P. expansum, but not from healthy fruits, had endoPG and exoPG activity. Culture filtrates and extracts of diseased tissue were subjected to vertical starch-gel zone electrophoresis. The number, location (anodic, cathodic), electrophoretic mobility, and relative activity of sites of endoPG or exoPG activity were determined by the species, virulence or avirulence of the strain, source of organic carbon, and gel pH.
CYATHUS SETOSUS, A NEW MEMBER OF THE NIDULARIACEAE FROM JAMAICA
Authors: Brodie Harold J.
Published: August 2008

A new species of Cyathus, C. setosus, of the Nidulariaceae, is described from Jamaica. The large brown-black cups are beset with long, durable setae. The fruit bodies are unusually thin-walled and very broadly conical. The nearest related species appear to be Lloyd's C. triples and C. nigro-albus, from each of which C. setosus is clearly separable.
LICHEN SUBSTANCES II: BIOSYNTHESIS OF CALYCIN AND PULVINIC DILACTONE BY THE LICHEN, PSEUDOCYPHELLARIA CROCATA
Authors: Maass W. S. G. , Neish A. C.
Published: August 2008

Tracer experiments with 14C-labeled compounds showed that phenylalanine, phenyllactic acid, and polyporic acid were readily incorporated into both pulvinic dilactone and calycin. Pulse-labeling experiments with phenylalanine and polyporic acid showed pulvinic dilactone was labeled more quickly than calycin, although eventually calycin may become more heavily labeled. These results can be explained by postulating the following sequence of reactions: phenylalanine → phenylpyruvic acid → polyporic acid → pulvinic acid → pulvinic dilactone → calycin.
ROLE OF TRACE ELEMENTS IN THE GROWTH AND MORPHOLOGY OF FIVE ASCOSPORIC ASPERGILLUS SPECIES
Authors: Agnihotri Virendra P.
Published: August 2008

The effect of copper, iron, molybdenum, boron, manganese, and zinc on the growth, morphology, and fruiting of five species of Aspergillus nidulans group was examined under controlled conditions. The fungi were A. nidulans (Eidam) Wint., A. rugulosus Thom and Raper, A. violaceus Fennell and Raper, A. varie-color (Berk. & Br.) Thom and Raper, and A. quadrilineatus Thom and Raper. Significantly less growth was noticed in all the fungi when all six trace elements were omitted from the culture medium. Also, marked morphological changes occurred in the mycelia and conidiophores of these fungi. The essentiality of manganese, iron, and zinc for growth and fruiting was established for all five fungi. In manganese-deficient cultures the mats were heavily wrinkled and several interesting changes and abnormalities were observed in the conidiophores. The reduction in growth in cultures deficient in copper, boron, and molybdenum varied with the species and their deficiency did not seem to reduce sporulation of these molds. Copper deficiency affected the pigmentation of these aspergilli.
HISTOLOGICAL STUDIES OF SYMPTOMS IN SEMIMATURE-TISSUE NEEDLE BLIGHT OF EASTERN WHITE PINE
Authors: Linzon S. N.
Published: August 2008

The incipient symptoms of needle blight of eastern white pine (Pinus strobus L.) appear only in semimature tissues of current year needles, and the orange-red lesions then spread acropetally throughout adjacent, more mature, tissues. Semimature tissue of white pine needles is characterized by the start of the suberization of the radial and transverse walls of the endodermal cells. The first cells to break down in blighted semimature tissue occur in the mesophyll region of one of the ventral faces of the needle. Mesophyll necrosis spreads laterally to the other ventral face and finally to the dorsal face of the needle, before proceeding distally through mature tissue. Anatomical differences exist between needles collected from susceptible and non-susceptible white pines.
MICROBIOLOGICAL AND BIOCHEMICAL ASPECTS OF HEARTWOOD STAIN IN BETULA PAPYRIFERA MARSH.
Authors: Siegle H.
Published: August 2008

Discoloration tests with wood meal and wood extracts showed that red heart of white birch (Betula papyrifera Marsh.) is the result of an enzymatic oxidation. Pyrocatechol, coniferyl alcohol, pyrogallol, and catechin, compounds found to be substrates for the staining process, were identified by thin-layer chromatography and ultraviolet spectrophotometry. Evidence was obtained that pyrocatechol, coniferyl alcohol, and pyrogallol are present in the heartwood as glycosides, whereas catechin occurs as a free compound. The reddish-brown stain of the wood is due to the oxidation products of the phenols involved.Fungi associated with red heart are the main producers of phenol oxidases which catalyze the discoloration process. The ability of Trichocladium canadense Hughes (=Torula ligniperda (Willk.) Sacc.) to cause red heart in white birch is questioned.
IDENTIFICATION AND DISTRIBUTION OF CIBORINIA WHETZELII (SEAVER) SEAVER IN WESTERN CANADA
Authors: Baranyay J. A. , Hiratsuka Y.
Published: August 2008

not available
CHYTRIDS AND ALGAE: I. HOST–SUBSTRATE RANGE, AND MORPHOLOGICAL VARIATION OF SPECIES OF RHIZOPHYDIUM
Authors: Barr D. J. S. , Hickman C. J.
Published: August 2008

Studies of pathogenicity and of morphological variation were made with pure cultures of Rhizophydium sphaerocarpum isolated from Spirogyra and of R. karlingii isolated from Ulothrix. R. sphaerocarpum was parasitic, virtually confined to species of Spirogyra amongst which there was a wide range of susceptibility. R. karlingii grew only on non-living algae and on pine pollen. The rhizoidal system of R. sphaerocarpum was quite variable in the extent of its branching. Variations in sporangium size and of the forms of the endobiotic portion of the thallus in R. karlingii grown on different substrates were observed. Such variations have been used in the past as the basis for creation of new taxa. Pathogenicity tests with Paterson's strain of R. sphaerocarpum confirmed that it is saprophytic on many algae and on pine pollen in contrast with the strain isolated from Spirogyra.
HOST REACTIONS TO THREE STRAINS OF ASTER YELLOWS VIRUS FROM MANITOBA
Authors: Richardson H. P.
Published: August 2008

One non-celery-infecting strain of aster yellows virus (NAYV) and two celery-infecting strains (CAYV-Z and CAYV) were isolated in Manitoba. Percentage transmission of the three strains of AYV to 13 plant species by single, infective male or female six-spotted leafhoppers (Macrosteles fascifrons (Stål)) given a 2-day inoculation feed varied with the host and virus strain. Head lettuce (Lactuca sativa var. capitata L.), and stinkweed (Thlaspi arvense L.) were superior to China aster (Callistephus chinensis Nees) as indicators of the proportion of infective leafhoppers. Acquisition of virus by vectors fed on the 13 plant species, as indicated by transmission to aster, differed according to strain and host. The differences between hosts in the percentages of plants infected with AYV was attributed to plant host – virus rather than the vector–virus relationships.There was no correlation between the susceptibility of a host and its value as a virus source. Head lettuce was the only one of the 13 plant species tested that was highly susceptible and from which all three strains of AYV could be readily acquired.
THE NITROGEN METABOLISM OF PICEA GLAUCA (MOENCH) VOSS AND PINUS BANKSIANA LAMB. AS INFLUENCED BY MINERAL NUTRITION
Authors: Durzan D. J. , Steward F. C.
Published: August 2008

White spruce (Picea glauca (Moench) Voss) and jack pine (Pinus banksiana Lamb.) seedlings were grown in sand cultures by Swan (who reported on their growth in 1960) and they were irrigated with full nutrient solution high in sodium, or solutions deficient in each of several nutrients. Responses characteristic of the following six treatments were studied: full nutrient but with low sodium; nitrate or ammonium as the sole source of nitrogen; low nitrogen; low phosphorus; and low potassium. When shoot elongation had ceased, extracts of seedling parts (leaves, stems with buds, and roots) were examined by paper-chromatographic methods for free nitrogenous compounds.In leaves, the relative proportions of nitrogenous compounds in spruce and pine differed from those in the stems and roots. Nutrient deficiency and the form of nitrogen available affected both the total amount and relative composition of the soluble nitrogen. Under better mineral nutrient conditions, arginine accumulated while amide (glutamine) remained low. The accumulation of a number of compounds resulting from nutritional deficiency, for example glutamine, with low potassium, indicated that blocks occurred in metabolic pathways. Ammonium nitrogen was shown to foster arginine and amides (especially in spruce) and to lead to a large increase of free guanidino compounds which hitherto have passed unnoticed. By contrast, in leaves nourished by nitrate as the sole source of nitrogen, guanidino compounds were less prominent. Under the conditions of reduced growth and protein synthesis brought about by specified nutrient deficiencies, many unidentified compounds, which were not known intermediates of the ornithine or urea cycle, appeared.The present study dealt with observations made at one season of the year (late summer) and does not preclude the occurrence of somewhat different responses which might have been observed at other times of the year.
TAXONOMY AND DISTRIBUTION OF THE MELOBESIOID ALGAE ON RONGELAP ATOLL, MARSHALL ISLANDS
Authors: Lee Robert K. S.
Published: August 2008

Seven growth forms of the species Neogoniolithon frutescens (Foslie) Setchell and Mason, Porolithon onkodes (Heydrich) Foslie, P. craspedium (Foslie) Foslie, and P. gardineri (Foslie) Foslie found on Rongelap Atoll are described in detail. Two of the growth forms are new combinations: N. frutescens f. flabelliformis (Foslie) Lee and P. gardineri f. abbreviata (Foslie) Lee. Porolithon craspedium and P. gardineri seem to be especially adapted to the atoll environment. The largest individuals and greatest density of organisms were produced by P. craspedium f. craspedium at the leeward reef margin and P. gardineri f. subhemisphaerica at the windward reef margin. With the exception of P. onkodes, a somewhat ubiquitous species, the distributional pattern displayed by the different species on the reef flat at Rongelap indicates that each has a narrow tolerance range for local variations in the environment.
HYBRIDIZATION OF FESTUCA SPECIES
Authors: Malik C. P.
Published: August 2008

Within the genus Festuca successful crosses have been made between five species belonging to the sections Ovinae, Bovinae, and Scariosae. These hybrids revealed close affinity among some of the species and in many cases the success of a cross depended upon a compatible genotype. Genetic evidence is presented to account for the morphological variability among some of the species. The role of introgression in the evolution of F. elatior Lin. complex is discussed.
INHIBITION OF RESPIRATION DURING PHOTOSYNTHESIS BY SOME ALGAE
Authors: Brown D. L. , Tregunna E. B.
Published: August 2008

An infrared CO2 analyzer was used to measure production and assimilation of CO2 by 11 marine or freshwater algae in acidic media. Considerable differences among the algae were found in the concentration of CO2 required to saturate photosynthesis and in the compensation concentration of CO2. High compensation values were always lowered by lowering the O2 concentration, even to concentrations which did not reduce respiration in the dark. It was concluded that respiration was inhibited during photosynthesis. In four of the algae, respiration was replaced by a different process of CO2 production during photosynthesis.
THE IDENTITY OF A SEED-BORNE MOSAIC VIRUS OF CHENOPODIUM AMARANTICOLOR AND C. QUINOA
Authors: Dias Humberto F. , Waterworth Howard E.
Published: August 2008

Seedlings of Chenopodium amaranticolor and C. quinoa were found to contain a highly infectious, seed-borne virus that may remain latent. Under certain environmental conditions and following abrasion of the leaves with carborundum and water, infected, symptomless young plants develop visible systemic symptoms. The presence and erratic behavior of the virus in these species can lead to erroneous identification of the causal agent of diseases of other crops. The virus is restricted to the Chenopodiaceae and is similar to Chenopodium mosaic virus (= sowbane mosaic virus) in morphology and in physico-chemical properties. It is serologically related to Chenopodium star mottle virus, to a latent virus isolated from apple in the USA and, by inference, to Chenopodium mosaic virus.
SEQUENTIAL CHANGES IN RATE OF ANTICLINAL DIVISION, CAMBIAL CELL LENGTH, AND RING WIDTH IN THE GROWTH OF CONIFEROUS TREES
Authors: Bannan M. W.
Published: August 2008

The early growth of a tree is marked by a widening of the annual increments, a deceleration in rate of multiplicative (anticlinal) division of fusiform cambial cells, and an increase in cell length. Distance outward from the pith at which maximation in cell size occurs, and subsequent trends in cell dimensions, are apparently modified by rate of growth. Continuation of a uniform ring width through the middle to late years favors comparative constancy in rate of anticlinal division and cell size during that stage of tree development. Reduction in amount of annual increment in the late growth to the width optimal for cell extension, about 1 mm, induces a delayed and probably heightened maximation in cell length. Continued lessening in radial growth to an annual accretion of 0.5 mm or less, with the onset of senility, results in acceleration in rate of multiplicative division and reduction in cell length.
ON THE OCCURRENCE OF PERIDERM IN THE LEAVES OF WELWITSCHIA MIRABILIS
Authors: Salema R.
Published: August 2008

The study of leaves of different ages from 20 specimens of Welwitschia mirabilis from the desert of Moçamedes, Angola, has shown that periderm develops at the edge of the leaves a few centimeters from the base. This periderm was produced by cambial activity of mesophyll cells. Similar activity in periderm formation was also noted in other areas, notably between the vein and the lower epidermis, and later also in the region above the vein. Apparently the initiation of cambial activity was dependent upon the presence of a vascular bundle. The longitudinal splitting of the leaf occurs where there are areas of mesophyll cell breakdown and periderm formation crossing the leaf from one surface to the other.
THE DIAPORTHACEAE: I. DITOPELLOPSIS GEN. NOV., DITOPELLINA GEN. NOV., PHRAGMOPORTHE AND DITOPELLA
Authors: Reid James , Booth Colin
Published: August 2008

Ditopellopsis n. gen. (type, Ditopellopsis clethrae n. sp.) and Ditopellina n. gen. (type, Ditopellina saccardiana (Trav. & Spessa) n. comb.) are described as members of the family Diaporthaceae, order Sphaeriales and contrasted with Phragmoporthe Petrak and Ditopella DeNot.
THE ERYSIPHE CICHORACEARUM CONIDIUM
Authors: McKeen W. E. , Mitchell N. , Smith R.
Published: August 2008

The wall of the conidium of Erysiphe cichoracearum was composed of two layers. The inner layer was probably chitinous and possessed a few spines, whereas the outer layer was three or four times thicker and gelatinous. The end wall of the spore often was incompletely covered with this gelatinous layer. The cytoplasm of the dormant conidium had electron-dark and electron-light areas. It contained mainly spherical or elliptical mitochondria, spherical lipid bodies, which were usually next to the conidial wall, a limited amount of endoplasmic reticulum, and occasionally storage bodies, perhaps glycogen. The chondriosomes appeared to reproduce by division. A large proportion of the volume of conidia was occupied either by a few large vacuoles or several small ones. The vacuoles occupied the central region of the conidium and contained varying amounts of heterogeneous material which could be storage and (or) waste substances and probably most of the water in the spore. Although neutral red did not stain the vacuole, the tonoplast appeared typical in electron micrographs. The nucleus was about equidistant from the ends of the mature conidium and contained a lateral granule which was frequently opposite to a prominent large nucleolus. Crystal violet, sudan black B, Giemsa, and Feulgen stains revealed that two or three unknown bodies were present in the nucleolus. An unidentified body was found also in the nucleoplasm. The Feulgen reaction was positive after fixation with glutaraldehyde but not after the fixatives of Helly and Farmer. When the last two fixatives were used, the nucleoplasm and chromatin were withdrawn a considerable distance from the nuclear membrane. Thus the fixative not only changed the morphology of the nucleus but also its chemical structure.
SEASONAL GROWTH CHARACTERISTICS OF LONG AND SHORT SHOOTS OF TAMARACK
Authors: Clausen J. Johanna , Kozlowski T. T.
Published: August 2008

Tamarack (Larix laricina (DuRoi) K. Koch) produces long shoots which bear two kinds of needles. Early needles are present in the bud and elongate rapidly after budbreak. Late needles, few of which are present in the bud, elongate later than early needles. Short shoots bear early needles only, and stem length seldom exceeds 1 mm. Seasonal changes in length and weight of needles and stems of both shoot types were measured. In long shoots, 75% of stem elongation, more than 70% of stem weight increment, and 65–70% of late needle elongation occurred after early needles were full-sized. Stem and late needle elongation ceased simultaneously, after which time needle weight decreased and stem weight increased. Early needles probably drew on food reserves while developing, and then themselves contributed to stem and late needle elongation. Final stem weight increase probably used photosynthate from both late and early needles of the current year.Shading of current and last year's needles showed that shoots in which photosynthesis was interrupted in this way produced shorter, lighter-weight stems than did control shoots.
THE STABILITY OF WHEAT EMBRYO GLUTAMATE DECARBOXYLASE UNDER CONDITIONS OF WATER STRESS
Authors: Nations Claude
Published: August 2008

The effect of various treatments on the stability of glutamate decarboxylase in wheat seedlings and wheat embryos was investigated in an effort to obtain information suggesting a molecular basis for desiccation resistance in plants. The decarboxylase activities of germinating wheat grains before and after desiccation were measured. Attempts were made to relate activity of the enzyme to a soluble or particulate cell fraction by differential centrifugation. The responses to desiccation by active protein preparations following defatting treatments with n-butanol were measured. The decarboxylase activity of germinating wheat increased for 54 h and the stability of the enzyme decreased during this time. Particulate cell fractions were devoid of activity. The responses of the extracted enzyme to desiccation suggest that its stability may reside in a capacity for dissociation into smaller protein components, under conditions of water stress, and that this capacity may depend upon the presence of lipids.
GROWTH AND DEVELOPMENT OF POTATO CALLUS IN SUSPENSION CULTURES
Authors: Bajaj Y. P. S. , Dionne L. A.
Published: August 2008

Potato callus raised from placental tissue was continuously grown in agitated liquid cultures. Best growth of the callus and its dissociation into single cells and clumps of cells was obtained in a medium containing Murashige and Skoog's minerals +2,4-dichlorophenoxyacetic acid (0.2 p.p.m.) +α-naphthaleneacetic acid (0.2 p.p.m.) + yeast extract (1000 p.p.m.). When a suspension of cells from this medium was transferred to fresh medium of the same composition, the clumps of cells proliferated further to form masses of callus. Occasionally, differentiation of roots from the callus was also observed. In media containing kinetin (0.2 p.p.m.) or 6(γ,γ-dimethylallylamino)-purine, large numbers of shiny, rounded pearl-like callus masses were obtained. The development of these callus bodies and their subsequent growth proved better when the kinin used in the medium was 6(γ,γ-dimethylallylamino)-purine.
INTERACTION OF NEAR-ULTRAVIOLET LIGHT AND TEMPERATURE ON SPORULATION OF THE FUNGI ALTERNARIA, CERCOSPORELLA, FUSARIUM, HELMINTHOSPORIUM, AND STEMPHYLIUM
Authors: Leach Charles M.
Published: August 2008

Alternaria dauci, A. tomato, Cercosporella herpotrichoides, Fusarium nivale, Helminthosporium catenarium, and Stemphylium botryosum, all Fungi Imperfecti, were grown on temperature gradient plates (5–40 °C) under different regimes of near-ultraviolet radiation (320–420 nm) and darkness. None of the fungi normally sporulated in darkness on the media used. The effects of interaction of temperature and near-ultraviolet radiation (NUV) on sporulation were significant for all six fungi. The fungi were grouped into two categories, "Diurnal Sporulators" (A. dauci, A. tomato, and S. botryosum) and "Constant Temperature Sporulators" (F. nivale, H. catenarium, and C. herpotrichoides). The "Diurnal Sporulators" have two distinct phases of photosporogenesis, an "inductive phase" leading to the formation of conidiophores, and a "terminal phase" resulting in the formation of conidia. The "inductive phase" is stimulated by NUV and operative at relatively high temperatures, while the "terminal phase" is strongly inhibited by NUV and blue light, and is operative at lower temperatures. In S. botryosum the "terminal phase" was completely inhibited by light at high temperatures but only partially inhibited at low temperatures.The "Constant Temperature Sporulators" in contrast, have a lower optimum temperature range for sporulation and show no clear separation of photosporogenesis into two distinct phases. Sporulation in this group is abundant under continuous exposure to NUV though it is even more abundant when exposure is followed by darkness.A new phenomenon, that of "high temperature induction" of sporulation, was observed in colonies of A. tomato and A. dauci. Relatively high temperatures caused these fungi to produce conidiophores in darkness, though only when the temperature was lowered did conidia form on the conidiophores. The amount of sporulation caused by "high temperature induction" was less than that caused by exposure to NUV.
GENETIC STUDY OF THE RESISTANCE OF COFFEA SPP. TO LEAF RUST: I. IDENTIFICATION AND BEHAVIOR OF FOUR FACTORS CONDITIONING DISEASE REACTION IN COFFEA ARABICA TO TWELVE PHYSIOLOGIC RACES OF HEMILEIA VASTATRIX
Authors: Noronha-Wagner M. , Bettencourt A. J.
Published: August 2008

The identification of four different and dominant genes conditioning the resistance reaction of Coffea arabica to Hemileia vastatrix has enabled us, following Person's method of analysis, to apply Flor's theory to this host–parasite system as well as to infer the genotypes of each of the twelve physiologic races used in this work, and predict the likely occurrence of four rust races which are not yet known.These data, together with the knowledge of the geographical distribution of the rust races, provide the basis of a coffee breeding program which is designed to improve resistance to H. vastatrix.
STUDIES ON SNOW ALGAE AND FUNGI FROM THE FRONT RANGE OF COLORADO
Authors: Stein Janet R. , Amundsen Clifford C.
Published: August 2008

The algae and fungi occurring in snowbanks in the Front Range of the Colorado Rocky Mountains are described and discussed. Whenever possible, details of the life cycle are given and correlated with reports in the literature. The effect of light on presence of carotenoid pigments is discussed for several species. The following organisms are reported: Carteria nivale; Chlamydomonas nivalis, Chlamydomonas spp.; Chodatella brevispina, Chodatella granulosa; Scotiella cryophila, S. nivalis, S. polyptera; Koliella nivalis; Rhizophydium sp.; Chionaster nivalis.
CIRCADIAN RHYTHMIC FLOWERING RESPONSES IN CHENOPODIUM RUBRUM: EFFECTS OF GLUCOSE AND SUCROSE
Authors: Cumming Bruce G.
Published: August 2008

An endogenous circadian rhythm of flower induction in Chenopodium rubrum that depends on the length of darkness interrupting continuous light has a smaller amplitude and damps out earlier when the light preceding and (or) following darkness is limited in intensity. Glucose or sucrose, fed to plants throughout darkness, can enhance and sustain the rhythm over a considerably longer period. Some degree of specificity of glucose in the rhythmic process was indicated because, when this energy source was applied during a skotophile phase of darkness (particularly the first 9 h) there were inhibitory effects on the rhythmic flowering response, but the same concentration of glucose was stimulatory when applied during the photophile phase(s) of darkness. No similar time dependence resulted from sucrose treatments. To account for the effects of glucose in particular, it is postulated that endogenous sugar formation in the light period is involved in providing substrate for phytochrome-Pfr action or mediation during darkness. Damping out of the oscillation in extended dark periods is a consequence of depletion of sugar reserves during darkness. These and other results support the concept that Pfr acts as a pacemaker or valve and exerts some control over sugar availability and utilization. Comparisons involving the application of glucose to different ecotypes suggest that, for optimal induction, some definite balance is required between the endogenous availability of glucose, or some other sugar derivative(s), and the level of phytochrome Pfr; this balance apparently differs according to genotype.Differences between ecotypes in their rhythmic flowering responses suggest that the endogenous free-running clock is an integral part of the time-measuring system in daily photoperiodic cycles and that it does have a role in measuring time under natural conditions.
DIATOM ASSEMBLAGES FROM PLEISTOCENE INTERGLACIAL BEDS AT TORONTO, ONTARIO
Authors: Duthie H. C. , Rani R. G. Mannada
Published: August 2008

Interglacial beds from the Don Valley brickyard at Toronto were sampled systematically for diatoms. In 34 samples, 11 contained diatoms, and a total of about 200 species and varieties were identified. The dominant species are Tabellaria fenestrata (Lyng.) Kütz, Opephora martyi Héribaud, Cocconeis disculus var. diminuta (Pant.) A. Cl., Amphora proteus Greg., and Achnanthes clevei Grun. The overall assemblage suggests deposition in a freshwater estuary in alkaline, mesotrophic, or eutrophic water. The variation in ecologic composition of the samples indicated shifting of the river channel or repeated shallowing and deepening of the estuary. With some exceptions, the diatom flora is typical of temperate North America today, but the lack of knowledge of the extant diatom flora precludes a closer comparison.
Transmission and biology of sunflower downy mildew
Authors: Goossen P. G. , Sackston W. E.
Published: August 2008

Sunflower seedlings grown in soil naturally infested with Plasmopara halstedii may not show symptoms of downy mildew, although the pathogen can be demonstrated in the tissues. Sporulation can be induced by placing infected seedlings in a saturated atmosphere for 12 hours. Inoculating seeds with a suspension of zoosporangia gave high percentage infection in about 14 days. Damping-off induced by P. halstedii, not previously attributed to this pathogen, occurred on sunflower seedlings in some inoculation experiments. Spore concentration was not critical for infection in the ranges tested, from 150 000 to 100 zoosporangia per milliliter. Zoosporangia stored on infected leaves at −20 °C germinated about 75% after 3 weeks, and about 10% after 14 weeks; none germinated after 24 weeks storage. Zoosporangia added to untreated soil remained infective for only 7 days; some remained infective in pasteurized and sterilized soils for 14 days. Zoosporangia did not germinate in distilled or tap water; germination occurred in 0.5% sucrose solution, but was better in 1 or 2% sucrose.
Effect of girdling on cambial activity in white pine
Authors: Wilson Brayton F.
Published: August 2008

There are no changes in cell dimensions more than 10 cm above a girdle in white pine (Pinus strobus L.), but up to 10 cm above, cell radial diameters are less, and at 2 cm cell walls may be thicker. There is an increase in number of cells produced from 2 to 310 cm above girdles, apparently because of a higher mitotic index and longer season for mitotic activity. The radial number of cells in the cambial zone does not change. From 2 to 310 cm below girdles mitotic activity and radial enlargement soon stop, cell wall thickening continues slowly, and there is no change in radial cell number in the cambial zone. These effects above and below girdles appear to be independent of time of girdling. They may be explained by the effect of girdling in blocking both the polarized auxin transport system and the non-polarized phloem transport system.
Nutritional control of the correlative inhibition between lateral shoots in the flax seedling (Linum usitatissimum)
Authors: McIntyre G. I.
Published: August 2008

When the epicotyl of the flax seedling is decapitated one of the two shoots produced at the cotyledonary node tends to inhibit and may completely suppress the growth of the other. By growing the seedlings in sand culture with a controlled mineral nutrient supply it was shown that (a) the inhibiting influence of the dominant shoot was inversely related to the nitrogen level; (b) the inhibited shoot could be released from inhibition by increasing the nitrogen supply; (c) the removal of the dominant shoot was followed within 12 h by an increase in the total nitrogen content of the inhibited shoot; (d) a similar control of inhibition could be obtained by varying the phosphorus supply. These results are consistent with the hypothesis that this form of correlative inhibition is due primarily to competition between the shoots for a limited mineral nutrient supply.When one of the cotyledons was either covered or removed its axillary bud was inhibited by the shoot in the axil of the untreated cotyledon. The degree of inhibition was inversely related to the nitrogen supply. It is suggested as a working hypothesis that the cotyledons provide a factor(s) which promotes the growth of their axillary buds and thus determines their ability to compete for mineral nutrients.
In vitro culture of a dwarf mistletoe, Arceuthobium pusillum
Authors: Bonga J. M. , Chakraborty C.
Published: August 2008

Embryos, small seedlings, and seeds of Arceuthobium pusillum Peck were cultured on White's medium supplemented with coconut milk and casein hydrolysate. The embryos increased in size up to five times their original length and often produced a holdfast at the tip of the radicle. Holdfasts with haustorial wedges were produced in cultures of small seedlings. In some of the seed cultures the radicles produced branches which showed many of the anatomical characteristics typical of young branches of the natural endophytic system inside the host bark. Occasionally a callus mass was formed at the base of the radicle and on the seed.
The respiration and flower development of evergreen azaleas as influenced by gibberellin, scale removal, and 2, 4-dinitrophenol
Authors: Ballantyne D. J.
Published: August 2008

Scale removal had little effect on time of flowering of Erich Schaame azalea flowers whether or not the azalea plants had been sprayed with gibberellic acid (GA3). Apparently the scales acted as a barrier to oxygen diffusion. GA3 treatments induced earlier flowering and an increase in oxygen uptake of the flowers. 2, 4-Dinitrophenol was more effective in stimulating the oxygen uptake of check flowers than in stimulating the oxygen uptake of GA3-treated flowers. DNP retarded the rate of flower development of GA3-treated flowers, but not of check flowers.
The ultrastructure of phycobiont and mycobiont in two species of Usnea
Authors: Chervin Ruth E. , Baker Gladys E. , Hohl Hans R.
Published: August 2008

The ultrastructure of two closely related species of lichens, Usnea rockii Zahlbr. and U. pruinosa Mot., was examined to determine the morphology of the phycobionts, the mycobionts, and their interrelation. The ultrastructure of the two species is essentially the same. A comparison of lichenized fungi and algal cells at the ultrastructure level was made with the ultrastructure of fungal and algal cells as known from the literature. The ultrastructure of the phycobionts is similar to that of free-living algae. The mycobionts displayed structural differences in their walls which apparently are unrecorded for fungus hyphae, resulting in a striking polymorphism of the hyphae. Close contact between mycobiont and phycobiont was seen, and intramembranous haustorial penetration of the algal wall was demonstrated in Usnea rockii.
Effect of pretreatment of pine seeds with herbicides on seed germination and growth of young seedlings
Authors: Sasaki S. , Kozlowski T. T. , Torrie J. H.
Published: August 2008

The effect of 24-hour pretreatment of Pinus resinosa Ait. seeds with herbicides, before the seeds are planted in soil, was studied on seed germination and seedling development over a 34-day period. Atrazine, simazine, or propazine at 200, 500, or 1000 p.p.m. did not affect seed germination significantly. At 500 and 1000 p.p.m. CDEC and EPTC had little or no effect on seed germination whereas CDAA and 2,4-D markedly inhibited both early and final germination. Atrazine and simazine were very toxic to young pine seedlings, with toxicity proportional to herbicide dosage. In contrast to atrazine and simazine, propazine did not kill seedlings during the 34 days of the experiment. At 500 p.p.m. CDEC and EPTC began to kill young seedlings at 24 days; 2,4-D at 27 days. CDAA, which had suppressed seed germination greatly, did not kill young seedlings. Marked morphogenic changes in seedlings were caused by pretreatment of the seed with EPTC, CDEC, or 2,4-D. CDEC and EPTC caused fused cotyledons; 2,4-D caused swollen stems and shrivelled cotyledons. At about 20 days after planting, the primary leaves of plants whose seeds had been treated with EPTC or CDEC (500 p.p.m.) emerged through a split at the base of the fused cotyledons. Higher dosages of these herbicides suppressed emergence of primary needles.
Influence of apical dominance on the nuclear proteins in cells of the lateral bud meristem in Tradescantia paludosa
Authors: Dwivedi R. S. , Naylor J. M.
Published: August 2008

In inhibited axillary buds of Tradescantia paludosa deoxyribonucleic acid, (DNA) synthesis is blocked at the 2C (GI) level in a group of cells which constitute a "zone of inhibition" in the bud apex. The apparent DNA/histone ratio of chromatin in these interphase cells is substantially higher than the "standard" value found in nuclei of the active terminal bud. The DNA/histone ratio of chromatin in the apex of the axillary bud declines to the standard level when the cells undergo changes leading to mitosis, after the release of inhibition. In contrast to the histone level, the total protein content of chromatin in the zone of inhibition is not influenced by the change in physiological state of the bud. The significance of this shift in the histone content of chromatin is discussed.
Effects of nitrogenous materials on translocation and stump exudation in root systems of tomato
Authors: Minshall Wm. Harold
Published: August 2008

An application of urea or of potassium nitrate to potted tomato plants in the 11- to 18-leaf stage of growth increased markedly the quantity of solutes in the stump exudate for the next 48 to 72 hours. This increase of solutes was most pronounced during the maximum part of the diurnal rhythmic cycle. A large proportion of the increased quantity of solutes was composed of asparagine, glutamine, aspartic acid, glutamic acid, nitrate, ammonium, etc. and thus directly related to the metabolism of the applied nitrogen. In addition, however, increased quantities of phosphorus and, at certain times, of potassium were noted.In detopped tomato plants the increased transfer of solutes from the treatment with nitrogenous materials increased the maximum rate of stump exudation from 2 ml/(plant × hour) for water control plants to 8 ml/(plant × hour). Single plants produced 80 ml of stump exudate in 24 hours. The time course effect on rate of exudation by the two forms of nitrogen differed in that potassium nitrate produced its maximum effect in from 6 to 8 hours following an addition at 0830 hours but urea produced its maximum effect in from 28 to 30 hours. By the fourth day the rate of exudation from nitrogen-treated plants was approximately the same as from water control plants.The Q10 for the rate of exudation of plants treated with nitrogenous compounds varied from 1.6 to 5.2 with an average value of 3.0. As the soil temperature was decreased from 18° to 8 °C the osmotic pressure of the stump exudate increased and the difference was statistically significant at the 1% level. Between soil temperatures of 18° and 28 °C, however, the difference in osmotic pressure of the exudates were not statistically significant. A reduced transport of water by physical means is suggested as the cause of the increase in osmotic pressure of the stump exudate at 8 °C.When plants treated with nitrogenous materials were compared to water control plants no support was found for the theory that active mechanisms participated in the transport of the water. In fact the marked increase in the osmotic pressure of the augmented exudates indicated that a lag existed in the movement of the water.It was concluded that the addition of nitrogenous materials to the soil increased by active processes the movement of solutes into the xylem sap of the plants. By osmosis the increased quantity of solutes then increased the quantity of water transported through the roots and collected as stump exudate.
Ecology of Phragmites communis. I. Photosynthesis of a single shoot in situ
Authors: Walker Jennifer M. , Waygood E. R.
Published: August 2008

Photosynthesis of a single shoot of Phragmites communis Trin. var. berlandieri (Fourn.) Fern., growing isolated from a stand, was measured in situ by enclosing it in a plastic bag of volume 107 liters and administering 1 mcurie of 14CO2 (specific activity, 5 mcurie per mmole) for 1 hour under a cloudless sky (light intensity > 100 000 lux; photoperiod, 16.5 h). The plant was 164 cm in height with 15 internodes, 11 expanded leaves, and a terminal unrolled leaf. The leaves, leaf sheaths, and internodes were removed, frozen between blocks of solid CO2, and subsequently extracted by the method of Bieleski and Turner (Anal. Biochem. 17, 278–293 (1966)). 14CO2 incorporation was determined in extracts of the plant parts by a scintillation analyzer.Photosynthetic rates were calculated per leaf, per square decimeter of leaf, per gram wet weight, and per μmole of leaf chlorophyll. Greatest incorporation of 14CO2 was found in the centrally inserted leaves. Leaf sheaths and internodes fixed only 8% of the total. Leaf area was the only useful index of photosynthesis averaging 6.1 (S.D. ± 0.62) mg CO2/dm2 per hour. On a gram wet weight basis the rate of photosynthesis increased in a hyperbolic relationship from the lowest to the uppermost leaves. Chlorophyll was determined on leaves from an adjacent plant of similar size and structure. On this basis the centrally inserted leaves were the least and the upper leaves were the most efficient, the uppermost expanded leaf having a rate of 163 µmoles CO2 per µmole chlorophyll per hour (assimilation time = 22 seconds). Productivity, in terms of carbon fixed, was 3.5 g/m2 per day based on a mean density of 12.75 plants per 0.25 m2 and a 10-hour day.
Investigations of the marine algae of Nova Scotia. V. Additional species new or rare to Nova Scotia
Authors: Edelstein T. , McLachlan J.
Published: August 2008

Forty-three species of marine algae new or rare to Nova Scotia are reported. Thirteen species of these are Rhodophyceae, 21 species Phaeophyceae, and 9 species Chlorophyceae. Two species, Halosacciocolax kjellmanii Lund and Acrochaete parasitica Oltmanns have been recorded before only from Greenland.
Polarity in the survival and elongation of fusiform initials in conifer cambium
Authors: Bannan M. W.
Published: August 2008

In conifer cambium both the continuation of the initial function after multiplicative division and subsequent cell elongation are under polar influence. In some cambial sectors the upper of the two sister-cell series produced by pseudotransverse division is more apt to persist than the lower sister series, and in these areas cell elongation is predominantly acropetal. In other sectors the reverse situation may hold. Although much variation occurs within the tree, general specific differences obtain with respect to the prevailing condition.
A natural first-generation hybrid between Rorippa barbareaefolia and R. islandica
Authors: Mulligan Gerald A. , Porsild A. E.
Published: August 2008

All the seeds taken from a fruiting specimen of Rorippa barbareaefolia (2n = 16) growing in the Yukon Territory produced plants with 24 somatic chromosomes. These plants were first-generation hybrids between R. barbareaefolia (2n = 16) and R. islandica (2n = 23). The female parent, R. barbareaefolia, was male sterile. Pairing configurations in pollen mother cells of these first generation hybrids suggested that the male parent, R. islandica, was autotetraploid.
Crystals in the wood of the genus Abies indigenous to Canada and the United States
Authors: Kennedy R. W. , Sastry C. B. R. , Barton G. M. , Ellis E. L.
Published: August 2008

The scanty and conflicting literature on distribution and nature of crystals in the ray parenchyma of Abies is reviewed before results are presented from this study of 318 trees. Crystals of rhomboidal and elongated forms were regularly present, in descending order of frequency, in A. concolor, A. grandis, A. magnifica, A. bracteata, and A. procera. Crystals were deposited predominantly in marginal ray parenchyma cells which died prematurely within a critical zone of sapwood. Both forms of crystals were regularly lacking in A. amabilis, A. balsamea, A. fraseri, and A. lasiocarpa, although fairly frequently elongated types were found in certain samples of the latter species. A pattern of very infrequent crystal distribution was found in association with juvenile wood in a single mature A. grandis, and in seedlings or saplings of several species.A quantitative scale of crystal frequency was developed and its application to wood species identification demonstrated. The lack of crystals in A. amabilis is offered along with other evidence to suggest a relationship between this species and those of the series Lasiocarpae Franco.Chemical characterization by thin-layer chromatography, atomic absorption, and histochemical procedures confirmed the older supposition that both forms of ray parenchyma crystals were calcium oxalate.
Periodicity and ecology of the phytoplankton in an oligotrophic and eutrophic lake
Authors: Bozniak Eugene G. , Kennedy Lorene L.
Published: August 2008

An oligotrophic and a eutrophic lake in Alberta were comparatively investigated for 14 months to elucidate relationships between the physicochemical environment and the species composition, seasonal succession, vertical distribution, and seasonal cycles of their phytoplankton. One hundred and seven algal species were found in Muir Lake and 63 species in Hastings Lake. Increases in the numbers of Anabaena flos-aquae accompanied decreases in the numbers of several green algae, viz Pediastrum and Scenedesmus spp., suggesting antagonistic effects. Three groups of vertical distribution patterns of phytoplankton occurred in both lakes: buoyant and some motile forms accumulated at or near the surface, a second group was more or less uniformly dispersed throughout the water column, and a third group occurred only in bottom waters. Intermittent species were classed as either stenochronic or eurychronic, depending on the length of their pulses. In Muir Lake, Asterionella formosa was inversely correlated with silica concentrations. Dinobryon increases were associated with increases in phosphates and bicarbonates. Up to 5 times more orthophosphate occurred in the ice than in the water beneath. Ice may be of heretofore unrealized ecological significance as a phosphate reservoir for the spring aquatic community.
Two new species of Ascocalyx
Authors: Groves J. Walton
Published: August 2008

Ascocalyx tenuisporus n. sp. occurring on Abies lasiocarpa (Hooker) Nutt. in the Yukon Territory and British Columbia, and Ascocalyx asiaticus n.sp. occurring on Abies pindrow Royle in Pakistan are described. They can be distinguished from each other and from Ascocalyx abietis Naumov by the size of the ascospores. Both species have conidial states belonging in the genus Bothrodiscus Shear. A new combination, Bothrodiscus berenice (Berk. & Curt, in Berk.) comb. nov., is provided for the conidial state of A. abietis.