Characteristics of the saprophytic reference strain FA ofClaviceps paspali

Growth properties and morphological features of the saprophytic collection cultureClaviceps paspali strain FA were investigated. The strain was characterized by a range of utilization of 13 carbon sources in a basic synthetic and a peptone medium. A temperature of 23 °C was more favourable for growth than 28 °C. Stages of changes of the culture cultivated for a long time on Sabouraud’s medium were detected by electron microscopy. The white culture was characterized by true septated mycelium with different types of terminal parts of hyphae. Arthrospores occurred after a 14-d cultivation, small spherical conidia released individually from hyphae were quite rare. As compared with other strains of the same species, strain FA did not form spherical clusters of conidia. On the other hand, a spontaneous rupture of the surface cell wall in different parts of hyphae and release of the cytoplasm were observed. In corn-steep containing media the formation of individual, pair and chain-like forms of arthritic conidia was stimulated. Destructive autolytic changes of hyphae were detected in the medium with potato extract.     

Saprophytic production of Clavine alkaloids and activity of Hydroxymethylglutaryl-CoA reductase

In submerged Claviceps cultures the activity of hydroxymethylglutaryl-CoA reductase preceded the increase of alkaloid production and of sterol content. During the first alkaloid phase, cell mevalonate was involved in the biosynthesis of both alkaloids and steroids. In the second production phase, it was predominantly used for alkaloid synthesis. Hydroxymethylglutaryl-CoA reductase appears to be a suitable target for physiological manipulation to increase clavine alkaloid yields.     

Glutamicin CBII,a bacteriocin-like substance produced by

Corynebacterium glutamicum CBII, in the stationary phase of growth, was found to produce spontaneously a substance resembling bacteriocins by its bactericidal properties. This substance designated glutamicin CBII was observed to exhibit bactericidal activity against coryneform bacteria (12 species tested) but not against unrelated gram-positive (3) and gram-negative (3) bacteria, while its action on bacteria with no quite known relatedness to the coryneform group (14) was found to be variable. Glutamicin CBII was partially purified by precipitation with ammonium sulphate (70% saturation), selective heat precipitation and gel chromatography on Sepadex G-50. The antibacterial substance diffused through cellophane membrane with an approximate cut-off of 10000 dalton and its sedimentation coefficient was determined to be 1.1. S by ultracentrifugation. Heating at 100°C for 30 min had no effect on its activity. Glutamicin CBII was proved to be resistant to chloroform, trypsin, chymotrypsin, pronase, and subtilisin. According to its staining behaviour and ¹H NMR spectra it probably represents a glycoprotein containing only a minor protein component.

---

     

Localization of aluminium in the leaves of some aluminium-accumulating species

Summary Transverse sections of leaves of some aluminium-accumulating and nonaccumulating species of the cerrado vegetation of central Brazil were coloured using aluminon to identify the tissues where aluminium occurs or is deposited. None of the tissues of the nonaccumulating species showed evidence of high concentrations of Al. All of the aluminium accumulating species showed high concentrations of Al in all of the elements of the phloem of the midrib and the secondary veins and total absence of it in the vessel members, xylem fibres and the palisade parenchyma. Walls and contents of the collenchyma of the midrib, epidermal cells, guard cells of the stomata and spongy parenchyma showed evidence of high concentrations of Al in the accumulating species.     

Seasonal changes in the photosynthetic response ofMercurialis perennis plants from different light regime conditions

Curves relating net photosynthetic rate to irradiance [P(I) curve relation] were estimated and analysed inMercurialis perennis L. plants stemming from three forest (spruce, beech and ash) stands with different tree leaf canopy development and different light regime. The saturating irradiance (I_s) reached the highest values in plants of all three stands in spring (spruce forest: 438 W m⁻², beech forest: 440 W m⁻² and ash forest: 367 W m⁻²), it declined sharply in the middle of the growing season (283, 285 and 297 W m^-2, respectively) and this I_s level persisted until autumn. A pronounced dynamics in plants from spruce and beech forests made itself manifest also in the adaptation (I_a) and compensating (I_c) irradiances, respectively. After a sudden decline in summer, values in autumn were close to those of the vernal season. The most pronounced parameter, which optimally expressed the adaptation ofMercurialis perennis to various light conditions, was the photosynthetic efficiency (α) calculated as the slope of the linear part of the curve relating net photosynthetic rate to irradiance. At the time of the highest P_{N sat.} value in course of the growing season (August) (spruce forest: 100, beech forest: 98.7 and ash forest: 85.8 μg CO₂ m⁻² s⁻¹), R_D was in its minimum; in autumn P_{N sat.} reached the lowest values which corresponded to the most intensive R_D. It was found thatMercurialis perennis plants stemming from forest stands with different light conditions did not make use equally of the altering light conditions in the course of the growing season. By the underlying analysis of P(I) curves this rhizomatous perennial herb (geophyte) may be characterized as a shade tolerant species.     

Radiation chemistry of a multicomponent aqueous system relevant to chemistry of cometary nuclei

Summary We have examined a water-dominated multicomponent system after irradiation in the multimegarad dose range with gamma rays from a⁶⁰Co source at both 77 and 310 K. The constituents were simple organic compounds in the proportions in which they appear in a dense interstellar cloud: HCN/CH₃OH/CH₃CN/C₂H₅CN/HCOOH=10.60.20.10.05. The total amounts were adjusted to correspond to a carbon to nitrogen ratio of 1.8 and a water content of about 50% in a cometary nucleus where the dust to volatiles ratio is 1; the total amount of CN-bearing compounds was taken to correspond to 0.4% of the cometary mass. In experiments at 310 K about 40 radiolytic products are identified, among them aldehydes and amino and carboxylic acids. Abundant polymeric material (M_w up to 80,000 daltons) is formed. The basic aspects of radiolysis of the liquid system are present also at 77 K, although at radiation-chemical yields that are lower by one to two orders of magnitude. We have considered the relevance of the present findings to the chemistry of a liquid-water core and the icy layers of a cometary nucleus.     

Radiation chemistry of an aqueous solution of glycine: compounds of interest to chemical evolution studies

Summary We have examined the radiolysis of an O₂-free aqueous solution of glycine at absorbed doses of⁶⁰Co gamma-radiation of up to 20 Mrad. At least 20 compounds are formed during radiolysis, among them several amino acids, an oligoamine, and the nitrogen-free polymers (M_w28,000 daltons). When dicyandiamide is present in the solution of glycine, various nitrogen-containing products, including some polymers (M_w12,000 daltons), are synthesized along with radiolytic products of glycine; polyglycines are not formed. We have determined the radiation-chemical yields of radiolytic-product formation and of decomposition of glycine, and have considered possible free-radical reactions leading to the radiation-induced changes observed.     

Sex differences in the response of rats to drugs affecting GABAergic transmission

The administration of diazepam 1.0 mg/kg decreased the level of plasma corticosterone in female but not in male Wistar rats. Picrotoxin, another drug affecting GABAergic transmission, also brought about an increase of plasma corticosterone in both sexes. However, in order to achieve a plasma corticosterone increase of similar magnitude (more than 500%) a threefold higher dose of picrotoxin had to be given to males. When the convulsive properties of picrotoxin were tested, it became evident that the dose of picrotoxin (2.5 mg/kg) which was subconvulsive in male was almost 100% convulsive in female rats. The existing sex differences in the response of rats to drugs affecting GABAergic transmission might have possible implications in the treatment of GABA system dysfunction.     

Canopy transpiration and water fluxes in the xylem of the trunk of Larix and Picea trees — a comparison of xylem flow,porometer and cuvette measurements

Summary Leaf gas exchange, transpiration, water potential and xylem water flow measurements were used in order to investigate the daily water balance of intact, naturally growing, adult Larix and Picea trees without major injury. The total daily water use of the tree was very similar when measured as xylem water flow at breast height or at the trunk top below the shade branches, or as canopy transpiration by a porometer or gas exchange chamber at different crown positions. The average canopy transpiration is about 12% lower than the transpiration of a single twig in the sun crown of Larix and Picea. Despite the similarity in daily total water flows there are larger differences in the actual daily course. Transpiration started 2 to 3 h earlier than the xylem water flow and decreased at noon before the maximum xylem water flow was reached, and stopped in the evening 2 to 3 h earlier than the water flow though the stem. The daily course of the xylem water flow was very similar at the trunk base and top below the lowest branches with shade needles. The difference in water efflux from the crown via transpiration and the water influx from the trunk is caused by the use of stored water. The specific capacitance of the crown wood was estimated to be 4.7 x 10^-8 and 6.3 x 10^-8 kg kg^-1 Pa^-1 and the total amount of available water storage was 17.8 and 8.7 kg, which is 24% and 14% of the total daily transpiration in Larix and Picea respectively. Very little water was used from the main tree trunk. With increasing transpiration and use of stored water from wood in the crown, the water potential in the foliage decreases. Plant water status recovers with the decrease of transpiration and the refilling of the water storage sites. The liquid flow conductance in the trunk was 0.45 x 10^-9 and 0.36 x 10^-9 mol m^-2s^-1 Pa^-1 in Larix and Picea respectively. The role of stomata and their control by environmental and internal plant factors is discussed.