bluuebunny/crossref_metadata_2025 huggingface dataset:
Escherichia coliHarboring a Natural IncF Conjugative F Plasmid Develops Complex Mature Biofilms by Stimulating Synthesis of Colanic Acid and Curli
Authors: May Thithiwat , Okabe Satoshi
Published: September 2008

It has been shown thatEscherichia coliharboring the derepressed IncFI and IncFII conjugative F plasmids form complex mature biofilms by using their F-pilus connections, whereas a plasmid-free strain forms only patchy biofilms. Therefore, in this study we investigated the contribution of a natural IncF conjugative F plasmid to the formation ofE. colibiofilms. Unlike the presence of a derepressed F plasmid, the presence of a natural IncF F plasmid promoted biofilm formation by generating the cell-to-cell mating F pili between pairs of F+cells (approximately two to four pili per cell) and by stimulating the formation of colanic acid and curli meshwork. Formation of colanic acid and curli was required after the initial deposition of F-pilus connections to generate a three-dimensional mushroom-type biofilm. In addition, we demonstrated that the conjugative factor of F plasmid, rather than a pilus synthesis function, was involved in curli production during biofilm formation, which promoted cell-surface interactions. Curli played an important role in the maturation process. Microarray experiments were performed to identify the genes involved in curli biosynthesis and regulation. The results suggested that a natural F plasmid was more likely an external activator that indirectly promoted curli production via bacterial regulatory systems (the EnvZ/OmpR two-component regulators and the RpoS and HN-S global regulators). These data provided new insights into the role of a natural F plasmid during the development ofE. colibiofilms.
Lignicolous marine fungi from southern Chile, including a review of distributions in the southern hemisphere
Authors: Hughes Gilbert C. , Chamut Patrick S.
Published: September 2008

Fifteen species of wood-inhabiting marine fungi recovered from intertidal wood collected in southern Chile (lat. 43°–55° S), eight Ascomycetes and seven Fungi Imperfecti, are new records for the cold temperate zone of the southern hemisphere. Three of the Ascomycete species were previously reported south of the equator from Australia and one of the Fungi Imperfecti is known from southern Brazil. Monodictys pelagica (Johnson) Jones was the most frequently collected species. The species composition of the Chilean collection is strikingly similar to the species composition of the intertidal lignicolous mycoflora of northern cold temperate waters. A distributional bipolarity is suggested for this group of "cold water" species. A review of lignicolous and algicolous marine fungi reported for the southern hemisphere is included.
Photosynthesis and photosynthate distribution in Douglas-fir strobili grafted to young seedlings
Authors: Rook D. A. , Sweet G. B.
Published: September 2008

In Douglas fir, scions bearing female strobilus buds were grafted to young seedlings. As the strobili developed, examination was made of the effect of their presence on photosynthesis and photosynthate distribution within the plant. At different times, the conelets constituted between 7% and 21% of the total dry weight of the plants.The presence of conelets did not significantly affect the photosynthetic rate of the leaves. It did, however, significantly alter the proportionate distribution of assimilates by restricting the amount of 14C photosynthate available for vegetative growth, particularly that of the roots and the current season's shoots.The conelets themselves had an appreciable rate of photosynthesis as shown by infrared gas analysis, 14-carbon labeling, and autoradiography. Per unit of chlorophyll, conelets were apparently some six times as efficient photosynthetically as leaves; per unit of dry weight, however, they were slightly less efficient than leaves.
Cytoplasmic connections between Dictyostelium discoideum cells
Authors: Kirk Drena , McKeen W. E. , Smith R.
Published: September 2008

Cytoplasmic connections between cells in the aggregation and migration stages of the cellular slime mold Dictyostelium discoideum Raper are shown, and some of the implications of such connections are discussed.
Illinois fungi. 1. Chaetosticta
Authors: Crane J. L.
Published: September 2008

The genus Chaetosticta Petr. & Syd. and its type species, C. perforata (Ell. & Everh.) Petr. & Syd., are redescribed and a lectotype is chosen.
Inheritance and qualitative analysis of pigments in a barley mutant
Authors: Stephansen Kari , Zalik Saul
Published: September 2008

Reciprocal crosses were performed with barley (Hordeum vulgare L. cv. ‘Gateway’) and a virescens mutant derived from it. The results from F1 and F2 generations of the crosses showed that chlorophyll deficiency was governed by a single recessive gene. Quantitative analysis of pigment concentrations in normal and mutant shoots of F1 and F2 plants of the same age provided evidence for heterosis in chlorophyll a synthesis.
Retardation of leaf senescence by benzyladenine in bean plants is not dependent on mobilization
Authors: Adedipe N. O. , Fletcher R. A.
Published: September 2008

Application of benzyladenine (BA) to portions of a bean leaf either along or across the midvein or to one of the two primary leaves, on intact plants, retarded senescence of the treated part. When 14carbon labeled CO2, IAA, leucine, or sucrose was fed to the untreated part on the same leaf, or to the untreated opposite leaf, there was less than 2% of the total radioactivity in the BA treated part after 24 h. It is concluded that retardation of leaf senescence by BA on intact bean plants is not dependent on mobilization of metabolites from other parts of the leaf.
Penetration and infection of alfalfa roots by Phytophthora megasperma and the pathological anatomy of infected roots
Authors: Marks G. C. , Mitchell J. E.
Published: September 2008

Penetration of the fine roots of Vernal alfalfa by Phytophthora megasperma was investigated in solution culture. The zoospores encysted on the root tips around the zone of cell division and cell extension and directly penetrated the host by a small infection peg. No appressoria were observed, but the flattened base of the cyst adhered to the host and appeared to serve the same function. Inside the root the hyphae were inter- and intra-cellular. In naturally infested and artificially inoculated field soils most of the fine roots were destroyed and large lesions appeared on the tap root. The latter originated from infection of the spongy-phellem cells formed around the base of the fine lateral roots. Restricted lesion development on the tap root was associated with the formation of wound periderm around the infection court. No wound periderm was formed when the vascular system was infected and only minor damage occurred when invasion was restricted to the cortex. Root damage reduced growth rates in older plants and severe infection produced yellow foliage, premature defoliation, and wilting.
Some ecological factors affecting the formation of Cenococcum mycorrhizae on basswood in southern Ontario
Authors: Park J. Y.
Published: September 2008

The effects of soil pH, ammonium nitrogen (NH4-N), nitrate nitrogen (NO3-N), and clay content on the formation of Cenococcum graniforme mycorrhizae on basswood (Tilia americana L.) were evaluated by assessing the degree of mycorrhizal infection of seedlings from natural forests in southern Ontario.Six hundred and thirty-nine basswood seedlings were collected, with adhering soil, from 22 woodlots between 43°30′ N. and 44°36′ N. The soils were mainly sandy and clay loams and the pH ranged from 6.2 to 8.4.The development of Cenococcum mycorrhiza was found to decrease as the pH, clay content, or NO3-N of the soil increased. Concentration of NH4-N was not found to be correlated with mycorrhizal infection. For a subsample of alkaline soils ranging in pH from 7.1 to 8.4, no correlation was evident between NO3-N and mycorrhizal infection.
Apical dominance in the rhizome of Agropyron repens. Some factors affecting the degree of dominance in isolated rhizomes
Authors: McIntyre Gordon I.
Published: September 2008

A study of apical dominance in isolated rhizomes of Agropyron repens L. Beauv. showed that increasing the length of the rhizome significantly reduced the degree of dominance only in rhizomes from plants grown at a high nitrogen level (210 ppm). Exposing the rhizomes to light also reduced dominance more effectively in high-nitrogen rhizomes but the response of rhizomes from low-nitrogen plants was greatly increased by supplying water through the end of the rhizome. Further experiments with low-nitrogen rhizomes showed that buds could be released from apical dominance by treatment with kinetin. When isolated from the plant the buds showed a significant increase in length after 24 h and an associated increase in moisture and insoluble nitrogen content. Soluble nitrogen and carbohydrate increased concurrently during the next 24 h. Rhizomes kept in darkness showed a small reduction of bud inhibition when water was supplied through the cut end; NH4NO3 solution had a greater effect, while solutions in which both nitrogen and carbohydrate (as sucrose) were supplied resulted in the almost complete elimination of apical dominance.The results suggest that apical dominance in isolated, low-nitrogen rhizomes was due mainly to competition between the apex and the lateral buds for water, nitrogen, and carbohydrate.
Seed water content in relation to phytochrome-mediated germination of lettuce seeds (Lactuca sativa L. var. Grand Rapids)
Authors: Hsiao A. I-Hsiung , Vidaver William
Published: September 2008

It is possible to distinguish two stages in the influence of light on the germination of Lactuca sativa var. Grand Rapids (lettuce) seeds. The first stage, which is represented by the photoactivation or transformation of phytochrome, requires only a relatively low seed water content. Slightly higher seed water content is required for maximum far-red light repression, than for red light stimulation of germination. The second stage is indicated by the well-known situation in which previous red irradiations of the seeds can enhance germination but this takes place only with relatively high seed water content. Phototransformed phytochrome appears to persist and to be susceptible to photoreversal for at least 24 h after irradiation in the seeds with relatively low water content.
Pollen germination of Tsuga heterophylla in vitro
Authors: Ho RongHui , Sziklai Oscar
Published: September 2008

The development of the male gametophyte from western hemlock (Tsuga heterophylla (Raf.) Sarg.) pollen was complete after 5 days of incubation. This normally takes at least 6 weeks in vivo. The pollen was cultured in a solution containing boron, calcium nitrate, magnesium sulfate, and potassium nitrate. In 2 days the generative cell divided into the body cell and the stalk cell and after a further 3 days the body nucleus divided into two sperm nuclei. Morphological descriptions and measurements of the germinating pollen grains were made.
Inhibition of phenylalanine ammonia lyase and enhancement of Avena coleoptile segment elongation by fluorophenylalanine
Authors: Hopkins W. G. , Orkwiszewski Joseph A. J.
Published: September 2008

Enhancement of elongation of Avena apical coleoptile segments by DL-fluorophenylalanines is specific for the para isomer. The ortho isomer is less than one-third as effective and the meta isomer has no effect. The in vitro activity of extractable phenylalanine ammonia lyase is inhibited equally well by para- and ortho-fluorophenylalanine and more strongly by the meta isomer. Inhibition was of the competitive type in all three cases. Chlorogenic acid levels were used to indicate the inhibition of phenylalanine ammonia lyase activity in vivo. Chlorogenic acid declined in controls. This decline was accelerated by the para isomer but not by the ortho isomer. The meta isomer protected against loss of chlorogenic acid. Enhancement of elongation was partially blocked by trans-cinnamic acid, ferulic acid and coumarin but not by chlorogenic, caffeic, or o-coumaric acids. It is postulated that p-fluorophenylalanine enhances elongation through depressed deamination of phenylalanine and consequent lowering of potentially inhibitory low molecular weight phenolic constituents.
The localization of nitrate-assimilating enzymes in leaves of plants with the C4-pathway of photosynthesis
Authors: Mellor Gary E. , Tregunna E. B.
Published: September 2008

The vascular bundle of leaves with the C4-pathway of photosynthesis is usually surrounded by two concentric chlorophyllous cell layers: an outer mesophyll layer and an inner bundle sheath layer. The localization of the nitrate-assimilating enzymes, nitrate reductase, nitrite reductase, and glutamate dehydrogenase in Zea mays, Gomphrena globosa, and Sorghum sudanense was studied by differential grinding. Nitrate reduction to nitrite appears to occur primarily in mesophyll cells. The nitrate content of the mesophyll cells was much higher than the nitrate content of the bundle sheath cells. The distribution of nitrite reductase seemed to be related to the presence of chloroplasts with grana. Ammonia incorporation into organic compounds by glutamate dehydrogenase was localized in the bundle sheath cells.
A study of Scirpus acutus and Scirpus validus in the Saskatchewan River delta
Authors: Dabbs Don L.
Published: September 2008

A study of Scirpus populations (section Pterolepis) in the Saskatchewan River Delta was conducted to examine morphological and ecological characters of the Scirpus acutus Muhl. and S. validus Vahl complex to determine whether or not they should be differentiated as species.Population collections from stands of Scirpus and stands of suspected clonal hybrids were taken in 1966 and 1968 from various locations within the delta of the Saskatchewan River. Environmental data such as water depths were recorded at time of collection.Two morphologically and ecologically distinct groups emerged; their hybrids were sterile or nearly so. The features of panicle ray length and floral scale length: achene length ratio were found to be diagnostic morphological criteria for separating the Scirpus examined into two sets of distinct populations. These two sets of populations differed ecologically in terms of water depth tolerances: the S. acutus type tolerates between 60 and 150 cm, whereas the S. validus type occurs only at depths less than 65 cm.It was concluded that in the geographic area in which they were studied, these two separate populations would best be regarded as separate species.
A technique to study the development in wood of soft rot fungi and its application to Ceratocystis ulmi
Authors: Casagrande F. , Ouellette G.B.
Published: September 2008

The development of fungi causing soft rots and of ensuing cavities in cell walls was studied with a new technique, consisting in inoculation of sterilized wood sections placed on agar slants. The senior author proposes a new system of classification of the soft rot fungi. Applied to investigations on Ceratocystis ulmi (Buism.) C. Moreau, this technique permits further characterization of the morphology of this fungus, including the formation of microhyphae and microspore-like particles, often less than 0.5 μ in diameter, and recognition of the various configurations brought about by its growth in wood tissues. For example, microhyphae grow in a reticulate manner in close contact with starch grains, and these seem to break down.
Daily variation of sorbitol and related carbohydrates in Malus leaves
Authors: Chong Calvin , Taper C. D.
Published: September 2008

The daily variation of sorbitol, starch, sucrose, glucose, and fructose were estimated in the leaf of the apple, Malus pumila Mill., at 2-h intervals over 24-h periods in each of the months June to October, inclusive, 1968. Marked daily fluctuation in sorbitol concentration was observed in all months, accompanied by more moderate variations in the other carbohydrates. The patterns of concentration variability in sorbitol and starch were relatively similar compared to the more irregular patterns of the three sugars, sucrose, glucose, and fructose. In conjunction with its invariably very high leaf concentration relative to the other carbohydrates, the general daily pattern of sorbitol content, namely, a marked nocturnal decrease followed by a great increase during daylight, indicated that sorbitol is the major photosynthetically derived carbohydrate and is further evidence that sorbitol is a reserve carbohydrate in apple leaves.
The use of Millipore filter discs in axenic culture of flax rust
Authors: Quick W. A. , Cross S. L. C.
Published: September 2008

The presence of Millipore filter discs on the agar medium resulted in more uniform, vigorous colonies of flax rust than were found when the colonies were grown directly on the agar surface. In addition, transferring and subculturing were greatly facilitated, and losses were greatly reduced.
Changes in carbohydrate metabolism in the wheat root tip after growth and vernalization
Authors: Ste-Marie G. , Weinberger P.
Published: September 2008

The serial section technique was used to delimit 0.5-mm regions of the root tip. Seven such sections numbered from the root tip backwards were examined to a total length of 3.5 mm.Developmental changes in the root tip cells of Marquis (spring) and Rideau (winter) wheats were closely correlated with sequential changes in the content of free sugars (sucrose, glucose, fructose, raffinose, and galactose), starch, and amylase. Specific varietal differences were observed both before and after vernalization.Spatially comparable root tip sections derived from previously vernalized grains revealed marked changes in the content of the sugars and starch. A shift in the starch–sugar equilibrium is noted with cellular development. For the most part, in Rideau wheat, the amount of these metabolites in any specific section derived from a vernalized root tip was more nearly comparable to the chronologically less mature tissue of the control roots, i.e. section 3 of the vernalized root compared more closely with section 2 of control roots.Amylase activity increased markedly after vernalization in the winter wheat but did not change in the spring wheat. Its activity could be directly correlated with changes in the amount of sucrose (not starch). Starch content increased in the more mature root tip cells of both varieties after vernalization.Sugar, amylase, and starch content were primarily a function of the developmental stage of the root tip cells, vernalization effected secondary smaller changes.
The axenic culture of Puccinia species from uredospores: experiments on nutrition and variation
Authors: Kuhl Joy L. , Maclean D. J. , Scott K. J. , Williams P. G.
Published: September 2008

Eighteen isolates of Puccinia were compared for ability to grow as saprophytes. After incubation of uredospores until growth ceased, six isolates developed an extensive mycelium, nine isolates formed a limited mycelium, and three isolates produced only scant saprophytic hyphae.The following factors were tested for their effect on the growth of P. graminis tritici race 126 Anz 6,7: inoculation from different uredosori; mode of application of the inoculum; density of the inoculum; composition of the medium. Using a dense inoculum it was found that yeast extract and peptone may be replaced by aspartic acid and a sulphur amino acid such as cysteine, and that glucose, fructose, mannose, or mannitol will substitute for sucrose as principal carbon source. However, no medium or method of inoculation was found to be completely reliable. A study of thinly seeded cultures showed that although 20–80% of sporelings could initiate saprophytic growth, only 3–6% eventually formed macroscopically visible colonies. It was found that frequencies of growth initiation and colony formation were highest on the thinnest layer of nutrient agar tested, and that sporelings mutually stimulated one another's growth. We conclude that the success of present culture techniques depends on an adequately high inoculum density, and other processes which are not understood.
Percurrent proliferations in fungi, algae, and mosses
Authors: Hughes S. J.
Published: September 2008

The production of new reproductive structures at the apex of successive percurrent proliferations is a common phenomenon in fungi. Successive sporangia and conidia in Phycomycetes, successive asci, conidia, phialides, and possibly 'gemmae' in Ascomycetes, and successive probasidia, basidia, and apparently urediniospores in Basidiomycetes, can be produced in this way. Examples of these are given from published accounts and some personal observations. Successive reproductive structures of various kinds are also formed on percurrent proliferations in 'green,' brown, and red algae. In the red algae successive antheridia can develop within empty ones by this method; it is concluded that such antheridia are not phialides. Successive gemmae in some mosses are formed terminally on percurrent proliferations.
Contribution of pentose phosphate pathway in developing castor bean endosperm
Authors: Agrawal P. K. , Canvin D. T.
Published: September 2008

Glucose-1-14C, glucose-6-14C, and glucose-U-14C were used to calculate the contribution of the PPP in developing castor bean endosperm tissues. Depending on the age of the seed 5–12% of the glucose-14C used was metabolized via the PPP and 88–95% via the EMP pathway. When lipid synthesis was rapid (20- to 28-day period) the PPP contribution was also at a maximum. During the 30- to 51-day period when lipid synthesis decreased so did the PPP contribution.With the data obtained from the PPP contribution the amount of NADPH produced during the experimental period was calculated. Also, the amount of fatty acids synthesized during that period was determined from glucose-U-14C data and thus the amount of NADPH required was calculated. Assuming that all the NADPH produced in the PPP was utilizable in fatty acid synthesis it was found that it was only sufficient to supply 50–75% of the reducing hydrogen required for fat synthesis. Therefore, the rest of the reducing hydrogen must come from some other sources, possibly NADH.
The taxonomy and heterothallism of Pythium sylvaticum
Authors: Pratt Robert G. , Green Jr. Ralph J.
Published: September 2008

Thirty-five of 83 Pythium isolates from Indiana were identified as P. sylvaticum by the production of sexual reactions and mature oospores in matings with the male and female type cultures of that species. Revised and expanded taxonomic descriptions of P. sylvaticum are presented. P. sylvaticum appears to be synonymous with P. debaryanum var. pelargonii. All P. sylvaticum isolates could be placed in heterothallic male or female groups. Many isolates were also homothallic. The mating system of P. sylvaticum does not represent sexual dimorphism because some isolates of the male group produced heterothallic sexual reactions in paired matings. Variations in sexual reactions indicate that P. sylvaticum comprises male and female isolates which differ in sexual strength.
Effect of Bipolaris sorokiniana on germination and seedling survival of varieties or lines of 14 Triticum species
Authors: Harding Howard
Published: September 2008

Seedlings of Triticum species and varieties differed markedly in reaction to inoculation with Bipolaris sorokiniana in laboratory tests. There appeared to be no consistent relationship between seedling reaction and previously established field disease ratings. The field-resistant line 680 of T. aestivum, in particular, was very susceptible in the seedling stage. There appeared to be no definite relationship between disease reaction and different genomic groups although resistance tended to increase with the ploidy level.There was some direct relationship between wheat seedling survival after inoculation and sensitivity to culture filtrates of B. sorokiniana. However, Conquest barley showed a high degree of seedling resistance to inoculation but was very sensitive to culture filtrates. Seedling survival was not related to speed of germination. Isolates of B. sorokiniana varied in degree of aggressiveness towards seedlings but this did not appear to be correlated with toxin production.
Growth response of western hemlock and Douglas-fir seedlings to temperature regimes during day and night
Authors: Brix H.
Published: September 2008

Growth of western hemlock and Douglas-fir seedlings was studied under 11 controlled day–night temperature regimes ranging from 8 to 28 °C, and with light intensities of 450 and 1000 ft-c for 100 days after seed germination. Production and distribution of dry matter, together with length and diameter of stem, were measured. Douglas fir had a broad optimum temperature for growth between 18 and 24 °C, whereas hemlock had a pronounced optimum at 18 °C, especially at high light. High temperature was more detrimental to growth of hemlock than of Douglas fir. At 28 °C, dry matter production of hemlock was 7, and of Douglas fir 40% of the maximum. Low temperature similarly affected the two plants. A constant day–night temperature regime was as good or better than alternating temperatures for both plants. Day temperature was more effective in increasing growth than night temperature. Light intensity, for most temperature regimes, had a pronounced effect on dry matter production, less on stem diameter, and little or none on stem length. Dry matter production of hemlock was considerably lower than for Douglas fir for all growing conditions.
Inorganic pyrophosphatases in leaves during plant development and senescence
Authors: Rauser W. E.
Published: September 2008

The activities of inorganic pyrophosphatases were determined in developing and senescing leaf tissues as indicators of biosynthetic activity. The level of alkaline inorganic pyrophosphatase varied with leaf age and leaf position on the plant. In younger plants alkaline inorganic pyrophosphatase increased up the plant to a maximum and then decreased with leaf proximity to the apex. In older plants the enzymatic activity decreased in the lower leaves and the maximum level occurred in leaves closer to the apex. Retardation of leaf senescence with benzyladenine maintained the high levels of enzyme activity. In cucumber plants removal of the shoot at any time before cotyledon death rejuvenated the cotyledons leading to excessive growth, regreening, and dramatic increases in alkaline inorganic pyrophosphatase. Alkaline inorganic pyrophosphatase activity correlated highly with 14C-leucine incorporation into protein of bean leaf discs, supporting the view that this enzyme is involved in making biosynthetic pathways irreversibly anabolic. Acid inorganic pyrophosphatase activity was not proportional to the alkaline activity, suggesting that two separate enzymatic proteins are being assayed. It is concluded that the level of alkaline inorganic pyrophosphatase can be used to indicate which plant parts have high biosynthetic capacity. Also, delayed senescence of leaves or cotyledons, with benzyladenine or apex excision, is associated with maintained biosynthesis.
Effect of O2 concentration and reference cell CO2 content on the calibration of infrared CO2 gas analyzers
Authors: D'Aoust A. , Bate G. C. , Canvin D. T.
Published: September 2008

When an infrared CO2 analyzer was calibrated with a gas mixture containing 21% O2 in the reference and measuring cells and then measurements performed with the same gas mixture with increased O2 content in the measuring cell, an apparent increased response was obtained to a particular CO2 concentration. This apparent increase was not due to increased sensitivity but was due to an increase in the "zero" position of the analyzer. The "zero" position of the infrared CO2 analyzer decreased as the CO2 concentration of both reference and sample cells was increased.
Induction of sexuality in heterothallic Pythium spp. by cholesterol
Authors: Child J. J. , Haskins R. H.
Published: September 2008

Cholesterol and related sterols were found to stimulate the sexual reaction between compatible strains of heterothallic Pythium species but were not essential to the mating process. The sterols induced the formation of antheridia, oogonia, and mature oospores in reportedly unisexual strains of P. catenulatum and P. sylvaticum but did not affect their corresponding compatible strains.
Disc electrophoretic comparisons of proteins and peroxidases from Phaseolus vulgaris leaves infected with Agrobacterium tumefaciens
Authors: Curtis C. R.
Published: September 2008

Soluble proteins extracted from Phaseolus vulgaris primary leaves infected with Agrobacterium tumefaciens were separated by disc electrophoresis and stained with Coomassie blue. Wounded but noninfected healthy leaves were used as a control. Gel scans revealed little difference in protein profiles between healthy and tumored leaves. Peroxidase isoenzymes were visualized on the gels with benzidine dihydrochloride – H2O2. Distinct differences were found in the number and activity of peroxidase bands between extracts. Extracts from tumored leaves contained more intensely stained peroxidase isoenzymes than healthy leaves. Leaves that were inoculated with a non-tumor-producing strain of A. tumefaciens had essentially the same protein and peroxidase profile as the healthy leaves.
Growth and respiration of psychrophilic species of the genus Typhula
Authors: Dejardin Rosamund A. , Ward E. W. B.
Published: September 2008

Growth of three snow mold fungi, Typhula idahoensis Remsb., T. incarnata Lasch ex Fr., and T. trifolii Rostr., was studied in agar and liquid culture. T. idahoensis was grown successfully in shake culture and its respiratory physiology investigated; some of the attendant problems are discussed.All three fungi were highly psychrophilic. The optimum temperatures for growth were 5–10 °C, the maximum about 20 °C and the minimum around −5 °C. Sclerotia were produced at all temperatures which permitted growth, but most abundantly at temperatures above 10 °C.Cultures grown at 10 °C ceased to grow on transfer to temperatures above 20 °C but, within limits, growth resumed on return to 10 °C after a lag period approximately proportional to the degree and duration of the temperature elevation.Oxygen uptake by T. idahoensis was optimal at 20 °C, about 15 °C higher than the optimum growth temperature.Respiratory quotients tended to be higher at 20 °C than at 5 °C and after starvation of the mycelium increased to a greater degree at 20 °C on addition of glucose or acetate. Starvation of the mycelium effectively reduced the level of endogenous reserves.The fungus was able to use, to differing degrees, a variety of hexose and pentose sugars as respiratory substrates. The percentage stimulation of the oxygen uptake by these sugars was greater at 20 °C than at 5 °C.
Growth responses of clonal lines of American sycamore grown under different intensities of nutrition
Authors: Steinbeck Klaus
Published: September 2008

Four random clones of American sycamore supplied with four concentrations of Hoagland's solution differed in their response to and interacted with treatment as far as height and diameter growth and total dry matter production in the first growing season were concerned. Varying nutrient intensity did not affect the time of the seasonal peak of height and diameter growth; better growth was maintained subsequent to the seasonal peak at the higher concentrations, however. The proportions of the trees in terms of dry-matter distribution and branching characteristics changed with nutrient concentration.
Spore surface morphology of pine stem rusts of Canada as observed under a scanning electron microscope
Authors: Hiratsuka Y.
Published: September 2008

Two types of surface markings on the aeciospores of five pine stem rusts occurring in Canada were observed under a scanning electron microscope. Spores of four species, Endocronartium harknessii (J. P. Moore) Y. Hiratsuka (= Peridermium harknessii J. P. Moore), Cronartium coleosporioides Arth. (= P. stalactiforme Arth. & Kern), C. comptoniae Arth., and C. ribicola J. C. Fisch., had annulated processes with five to seven layers and each spore had a smooth area. The smooth area was at the same level as the top layer of the processes. Each species could be distinguished by the shape and size of its processes. Spores of Cronartium comandrae Pk. had no smooth areas and had obtuse or cuspidate processes with no annulations. Different ontogenies were apparent for the two types of spore surface markings.
Response of lodgepole pine seedlings to inoculation with Europhium clavigerum, a blue stain fungus
Authors: Shrimpton D. M. , Watson J. A.
Published: September 2008

Seven days after inoculation with Europhium clavigerum (Robinson and Davidson), lodgepole pine seedlings showed an external flow of oleoresin. On the sapwood surface, a white streak extended above and below the wound. The sapwood adjacent to the inoculation was gradually impregnated with resinous compounds, and the bark adhered to the sapwood around this zone of resin-soaking. After 21 days, callus tissue had developed around the margin of the resinous area, and 1 year later, the xylem and the phloem had begun to overgrow the resinous area.The terpenes identified in 60-day-old resinous response from both seedlings and mature trees were β-phellandrene, 3-carene, α-pinene, camphene, β-pinene, myrcene, limonene, and p-cymene. The phenolic substances present in each were pinosylvin, pinosylvin monomethylether, pinobanksin, and pinocembrin.
The fine structure of the haustorium of Uromyces appendiculatus in Phaseolus vulgaris
Authors: Hardwick N. V. , Greenwood A. D. , Wood R. K. S.
Published: September 2008

Examination of the fine structure of the haustorium of Uromyces appendiculatus in Phaseolus vulgaris revealed a hitherto undescribed structure, the neckband, a short zone of darkly staining deposit in the stem of the haustorium. This occurs above that part of the wall of the stem which is associated with the sheath around the base of the haustorium and below the wall of two distinct layers belonging to the body of the haustorium.
In vitro induction of vegetative buds in tobacco callus by chelating agents
Authors: Kochhar T. S. , Bhalla P. R. , Sabharwal P. S.
Published: September 2008

Calli obtained from haploid and diploid plants of Nicotiana tabacum were inoculated on nutrient media supplemented with various concentrations of chelating agents: iron salt of ethylenediamine-di-o-hydroxyphenylacetic acid (Fe-EDDHA), 1,3-diamino-2-hydroxypropane-N,N,N′,N′-tetraacetic acid (DHPTA), 1,2-cyclohexanediaminetetraacetic acid (CYDA), citric acid, and tartaric acid. No auxin or cytokinin was added to the medium. Vegetative buds differentiated on the callus obtained from the haploid plants. However, these chelating agents proved ineffective in inducing differentiation on the callus derived from diploid plants. Morphogenetically, Fe-EDDHA and DHPTA proved more potent than CYDA, citric acid, and tartaric acid.
Nitrogen requirements of the fungal endophytes of Arundina chinensis
Authors: Stephen R. C. , Fung K. K.
Published: September 2008

The nitrogen requirements of two Rhizoctonia fungus endophytes of the orchid Arundina chinensis are reported. Both isolates were capable of using ammonium and organic nitrogen but not nitrate or atmospheric nitrogen. Glutamic acid and urea were the best of the nitrogen sources tested followed by arginine, then asparagine. Proline and methionine were not used. The addition of a mixture of vitamins to the amino acids increased growth of one of the isolates but not the other. Yeast extract supported greatest growth.
Ultrastructure of tobacco mosaic virus lesions and surrounding tissue in Phaseolus vulgaris var. Pinto
Authors: Spencer D. F. , Kimmins W. C.
Published: September 2008

Leaves of Phaseolus vulgaris var. Pinto were inoculated with the U1 strain of tobacco mosaic virus TMV (U1) and fully expanded lesions and adjacent healthy tissue were examined in the electron microscope. Emphasis was placed on the band of healthy cells (resistant zone) surrounding the lesion, with the object of detecting the first changes in ultrastructure as healthy tissue graded into the infected area. Cells in the resistant zone were characterized by the appearance of membrane-bound vesicular bodies (paramural bodies) between the plasmalemma and cell wall. Where paramural bodies accumulated, the plasmalemma was withdrawn and intercellular cytoplasmic connections through the plasmodesmata were severed. These changes were found most frequently for a distance of about three cell diameters beyond cells visibly infected at the lesion periphery. It is suggested that these changes in ultrastructure are related to the events of localization. Spread of the virus may be inhibited because of a lack of cytoplasmic connections between cells surrounding the virus-induced lesion.
Histological study on the in vitro induction of vascularization in tobacco pith parenchyma
Authors: Forest J. C. , McCully Margaret E.
Published: September 2008

The direct addition of indole-3-acetic acid and sucrose into sterile-cultured segments of tobacco pith via micropipettes has induced cell division and vascularization in a specific arrangement below the tip of the micropipette. The histology of this vascularization is described and it is shown that the orientation of the explant on the basal medium influences callus and bud formation.
Girdling: its effect on carbohydrate status and on reproductive bud and cone development of Douglas fir
Authors: Ebell L. F.
Published: September 2008

Partial girdles were applied in August, 1957, to one stem of two double-stemmed, 20-year-old Douglas fir (Pseudotsuga menziesii (Mirb.) Franco). The second stem served as control. A third double-stemmed tree was treated in May, 1958. Cone production responses were obtained on all three girdled stems, averaging 7.4 times that of control stems in 1959, and 1.6 and 2.3 times that of control stems in 1961 and 1962. Cone production responses to treatment, and cone crop variation over several years were correlated with reduced bud failure during the period of new shoot elongation. Total number of buds per shoot was initially similar for paired stems. These relationships indicated a predetermined potential for annual cone production, and that cone crop periodicity is determined by later conditions favorable or unfavorable to continued early bud development. Treatment increased both sugars and starch in shoots sampled 40 days after August girdling, but only starch remained elevated the next spring and throughout the decisive May–June period of reproductive bud development. Other factors indicated food reserves to be related only weakly to reproductive bud survival. Cone production reduced carbohydrate concentration in shoots of all ages, growth and number of new shoots, and number of developed buds per shoot. These factors explain the absence of consecutive cone crops in Douglas fir, and suggest that cone inducing treatments should not be applied in good flowering years. Cone production responses on single-stemmed trees girdled at weekly intervals showed an optimum timing coincident with the onset of flowering, a more variable response up to the time of vegetative bud break, then an adverse effect on cone production when girdled later than 1 week after vegetative bud break.
Correlation of phytochrome transformations with photocontrol of Avena coleoptile segment elongation
Authors: Hopkins W. G.
Published: September 2008

Loss of photoreversibility in phytochrome-dependent Avena apical segment elongation has been reexamined. The effect of intervening darkness between red and far-red irradiations has been corrected for elongation achieved during that period. Maximum reversibility is maintained for the first 7 h, followed by a rapid decline in reversibility from 7 to 9 h. Loss of spectrophotometrically detectable Pfr is about 90% during the first 7 h and approaches 100% by 9 h. The absence of correlation between level of reversibility by far-red light and loss of Pfr from the system is similar to observations previously reported for Phaseolus hook opening.Increase in the irreversible increment of elongation occurs at about the same rate as the increase in the ratio of Pr to total phytochrome. These results suggest that a role for Pr in controlling Avena coleoptile elongation should be considered.
The effects of salinity on germination and early growth of Puccinellia nuttalliana
Authors: Macke Allan J. , Ungar Irwin A.
Published: September 2008

Seed germination studies indicate that Puccinellia nuttalliana can germinate in media with a water potential to −16 bars, with a sharp decrease in germination at −12 bars. Recovery from −42 bars is generally equal to that of control tests, indicating high salinities do not permanently inhibit germination. Seedlings are stimulated at −4 bars, but growth shows a sharp decrease between −8 bars and −16 bars. Growth and flowering are promoted by long days. P. nuttalliana is not an obligate halophyte, but is tolerant of salinities which most nonhalophytes cannot endure.
Some Coelomycetes with appendaged conidia
Authors: Pirozynski K. A. , Shoemaker R. A.
Published: September 2008

Comatospora suttonii Pirozynski & Shoemaker, a new Coelomycete on twigs of Picea mariana (Mill.) BSP. in Canada is described and compared with Neottiospora caricina (Desm.) Höhn., Tiarosporella paludosa (Sacc. & Fiori) Höhn. var. paludosa (= T. schizochlamys (Ferd. & Winge) Höhn.), and var. graminis var. nov., Giulia tenuis (Sacc.) Tassi ex P.A. & D. Sacc, and Tiarospora perforans (Rob.) Höhn.
Scanning electron microscopic studies of wax formations on leaves of higher plants
Authors: Davis D. G.
Published: September 2008

A scanning electron microscope was used to observe variations in wax formations on leaves of cabbage (Brassica oleracea L., var. Capitata greenback), corn (Zea mays L., hybrid var. NK KE 449), cherry laurel (Prunus laurocerasus L.), and pea (Pisum sativum L., var. Little Marvel). Results obtained by this technique compare favorably to results from a carbon replica technique. The size and shape of the wax formations on adaxial and abaxial surfaces of the same leaf differed in all genera. A study was made of surface wax development on pea leaves. Wax "crystals" on the abaxial surfaces were larger than those on the adaxial surfaces. Individual wax crystals on the first-formed leaves were two to three times larger than those on the sixth-formed leaves. Results were similar for peas, whether they were grown in growth chambers or greenhouses; this indicated that subtle changes in environment do not greatly affect the appearance of wax formations. The question of cuticular pores is discussed.
The effects of prolonged darkness and light on the fine structure of Ceratodon purpureus
Authors: Valanne Niina
Published: September 2008

A description is given of the ultrastructure of moss spores incubated in darkness and posttreated with monochromatic light. Fine structural changes occur in darkness, especially in the chloroplasts, and are also noted with inorganic medium, in spite of the lack of germination. The most conspicuous is the increase of starch grains in the chloroplasts at the beginning of the dark-incubation, and their subsequent disappearance, which coincides with an increase in the number of grana lamellae. A synthesis of chlorophyll is correlated with the decrease of the starch. The incubation of sporelings in a 0.1% solution of sucrose results in the degeneration of the chloroplasts to amyloplast-like with concentrated lamellae and the accumulation of fibrillar material in the cytoplasm. When exposed to blue and red light, the chloroplasts of both inorganic and sucrose cultures develop into normal chloroplasts. A comparison of the effects of different wavelengths of light shows that the chloroplasts of sporelings exposed to blue light remain richer in starch and have a denser stroma than red-light chloroplasts. Red light allows more effective use of reserve lipids, but there are more mitochondria after blue light. No great differences in the lamellar structures of the chloroplasts can be noted between sporelings exposed to blue and red light, unless the illumination is of very long duration.
Choline contents of healthy and rust-infected primary leaves of wheat
Authors: Kim W. K.
Published: September 2008

Choline content in healthy and rust-infected primary leaves of wheat was determined by microbiological assay with Neurospora crassa. Rust infection increased the content of free choline, but not the content of lipid choline in susceptible or resistant leaves.
Dolabra nepheliae and its imperfect state associated with canker of Nephelium lappaceum and N. mutabile
Authors: Zalasky H. , Nawawi A. , Ting W. P. , Tai L. H.
Published: September 2008

Dolabra nepheliae Booth and Ting is redescribed from the type and its imperfect state is described as Rhabdospora nepheliae sp. nov. New information on host and geographic distribution is also reported.
Observations on Phaeosaccion collinsii in culture
Authors: McLachlan J. , Chen L. C.-M. , Edelstein T. , Craigie J. S.
Published: September 2008

The life history of Phaeosaccion collinsii Farlow, a species which is known from a single locality in Nova Scotia, has been completed in culture. There was no indication of a sexual phase and zoospores gave rise directly to the tubular thallus. Completion of the life history occurred at 5 °C only. At higher temperatures spores failed to germinate, or growth and differentiation were suppressed. Light intensities exceeding 100 ft-c inhibited spore germination, although growth and differentiation were not similarly affected. In nature mature plants occur sublittorally, and are present only in spring when the water temperature is around 5 °C. Zoospore flagellation is of the typical heterokont type with the flimmer bearing bilateral hairs. On this basis P. collinsii can be placed either in the Chrysophyceae or Phaeophyceae.
Stomatal opening: the role of abscisic acid
Authors: Horton Roger F.
Published: September 2008

Abscisic acid inhibits stomatal opening in isolated abaxial epidermal strips of Vicia faba. Kinetin, benzyladenine, and gibberellic acid, which can enhance stomatal apertures in intact leaves, are ineffective on isolated epidermal strips. Abscisic acid appears to act directly on the guard cells, rather than by influencing water potentials throughout the leaf.
Effect of chloramphenicol on membrane transformations in plastids
Authors: Srivastava L. M. , Vesk M. , Singh A. P.
Published: September 2008

At a concentration of 4 mg/ml chloramphenicol does not affect the formation and fine structure of prolamellar bodies. It also does not inhibit their light-induced loss and conversion into thyllakoids. It does, however, strongly affect the aggregation of thyllakoids into grana, most likely by retarding or interrupting some process(es) vital to the orderly assembly of thyllakoids. These results are discussed in light of the known effects of chloramphenicol on formation of pigments, electron-transfer and fraction I protein, and plastid membranes. It is suggested that the aggregation of thyllakoids into grana in higher plants may be regulated by some protein(s) synthesized by the plastid ribosomes, whereas the formation and maintenance of prolamellar bodies as well as the synthesis of plastid membranes may be regulated by protein(s) synthesized in the cytoplasm.
Conidium ontogeny in hyphomycetes. Development and morphology of Cladobotryum
Authors: Cole Garry T. , Kendrick Bryce
Published: September 2008

Conidium formation in Cladobotryum variospermum (Link) Hughes is analyzed by time-lapse photomicrography, and a developmental concept of the genus is proposed. We show how this concept can be reconstructed from observations of conidiogenous cells and conidia fixed at various ages. The morphology of conidiogenous cells and conidia of C. mycophilum (Oudem.) W. Gams and Hoozem., and C. dendroides (Bull. per Mérat) W. Gams and Hoozem. is interpreted in terms of development, and comparisons drawn with C. variospermum. We recommend that C. dendroides be excluded from Cladobotryum.