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Cylindrocarpon destructans (Zins.) Scholt. (C. radicicola Wr.) (Booth 1966) is known to be a common root surface inhabitant of many plants (Gerlach 1961, Matturi and Stenton 1964). This fungus has been isolated from the roots of both healthy and diseased plants. Because of its abundance on the root surface, it is considered to be a pioneer colonizer of this ecological niche (Stenton 1958, Matturi and Stenton 1964). According to Matturi and Stenton (1964) C. radicicola is not specialized in the direction of parasitism. On the other hand the pathogenicity of this fungus has been well documented by many investigators. A review of its phytopathological importance is given by Gerlach (1964) and Scholten (1964). Pathogenicity of C. radicicola for forest trees seedlings has been reported by Kluge (1966), Manka and Gierczak (1971), Kowalski (1980). According to Cartwright (cf. Evans et al. 1967) strains of this fungus can produce typical symptoms of disease, even without actively invading seedlings. This fact would suggest that they may affect the plant by their metabolites excreted into the root zone of plants. A toxic metabolite – nectrolide &nash; was detected in C. radicicola cultures by Evans et al. (1967). Analysis of nectrolide established the formula C&sub16;H&sub24;O&sub4; its physical and chemical properties were identical as the antibiotic Brefeldin "A" produced by Penicillin bn-fcldiamnn (cf. Evans et al. 1967). These authors suggest that if nectrolide is responsible for the stunting of seedlings, the compound must be produced at the surface of living roots. Many authors are of the opinion that because of the intimate contact of microorganisms with the plant cells in the root zone, microbial metabolites may directly affect development, growth and health of the plant (Hussain and Vancura 1970, Brown 1972, Barea and Brown 1974). Synthesis of plant growth regulators by microorganisms of the rhizosphere and rhizoplane of different plants has been well docum... [ABSTRACT FROM AUTHOR]

In comparative studies on potyviruses from West African yams (Dioscorea spp.) the following isolates were used: Dioscorea greenbanding mosaic virus (DGMV) and a Nigerian yam virus (YV-N), both isolated from Dioscorea rotundata, and a beet mosaic virus isolate from D. alata (BtMV-Y) formerly designated Dioscorea alata ring mottle virus. Naturally infected D. alata containing very few particles of BtMV-Y, contained primarily particles of a second potyvirus (Dioscorea alata virus, DaV) which could not be transmitted but which was included in these studies wherever possible. The normal lengths of DGMV, YV-N, DaV, and BtMV-Y were 754, 772, 805, and 812 nm, respectively. All viruses induced cytplasmic inclusions of the pinwheel type and laminated aggregates. In addition, the nucleoli of BtMV-Y infected cells contained characteristic electron dense inclusions. The buoyant density of purified DGMV and BtMV-Y in CsCl was 1.336 g/cm3 and 1.321 g/cm3, respectively. The sedimention velocities (Srei) of DGMV, YV-N, and BtMV-Y were 156, 158, and 162 S, respectively. In SDS-polyacrylamide gel electrophoresis the coat protein of purified DGMV and YV-N all migrated as a single band with an apparent molecular weight of 36 kd. Coat protein of purified DaV showed up to 5 bands with molecular weights of 36 to 32 kd. Polypeptides of purified BtMV-Y had an estimated molecular weight of 35 kd but those from infected plant extracts had a molecular weight of 36 kd. DGMV, YV-N, and BtMV-Y particles contained a single nucleic acid with an apparent molecular weight of 3.2, 3.2, and 3.1 Md, respectively. Using X-DNA digested with Hind III as a marker, the molecular weight of DGMV and BtMV-Y nucleic acid was calculated to be 3.6 Md ±10%. The nucleic acid was determined to be single-stranded RNA by enzymatic digestion and by staining with acridine orange. [ABSTRACT FROM AUTHOR]

Studies were carried out on the effect of pH, temperature, light and bacteria and actinomycetes on the pathogenieity of Cylindrocarpon destructans to pine seedlings. Two isolates, pathogenic to fir and pine were used. Depending on the cultural conditions both isolates were more or less pathogenic to pine. The isolate Dkm 229 exhibited much stronger pathogenic activity than the other one. The pathogenicity of the fungi depended upon the pH, temperature, light and accompanying microorganisms (bacteria and actinomycetes). Optimum pH for the pathogenicity of isolates Dkm 229 and Pkj 376 was 7,0 and 6,0 respectively. The aggressiveness of the strain Dkm 229 increased at lower temperature (15-18°C) and at lower light (700-800 lux). The isolate Pkj 376 exhibited a stronger pathogenicity at higher temperature (21-23°C) and higher light intensity (2100-2300 lux). Bacteria and actinomycetes introduced to the seedlings before fungal inoculation diminished the aggressiveness of the isolate Dkm 229, No such influence of both organisms on isolate Pkj 376 was noted. [ABSTRACT FROM AUTHOR]

Presents an obituary of Professor Dr. Heinz Kern, formerly director of the Institute for Special Botany at the Eidgenossische Technische Hochschule (Confederate Technical University) in Zurich. Details of his life and accomplishments.

Ablation of the cavotricuspid isthmus (CTI) to create bidirectional isthmus blockade is the most effective way to achieve rhythm control in typical atrial flutter. Compared with drug therapy, ablation reduces cardiovascular mortality, all-cause mortality, stroke risk, and the risk of cardiac decompensation. Concomitant arrhythmia of atrial flutter is atrial fibrillation (AF); therefore the duration of oral anticoagulation should be adapted according to the risk of stroke and bleeding. A combined procedure of CTI ablation and pulmonary vein isolation (PVI) in patients with typical atrial flutter but without evidence of AF should be evaluated individually especially in patients aged > 54 years depending on (cardiac) comorbidities. The comprehensive diagnostic view should keep in mind not only arrhythmias but also possibly underlying coronary artery disease., (© 2023. The Author(s), under exclusive licence to Springer Medizin Verlag GmbH, ein Teil von Springer Nature.)

The production of enzymes involved in mycoparasitism by several strains of ectomycorrhizal fungi: Amanita muscaria (16-3), Laccaria laccata (9-12), L. laccata (9-1), Suillus bovinus (15-4), S. bovinus (15-3), S. luteus (14-7) on different substrates such as colloidal chitin, mycelia of Trichoderma harzianum, T. virens and Mucor hiemalis was examined. Chitinases and beta-1,3-glucanases were assayed spectrophotometrically by measuring the amount of reducing sugars releasing from suitable substrate by means of Miller's method. Beta-glucosidases were determined by measuring the amount of p-nitrophenol released from p-nitrophenyl-beta-D-glucopyranoside. It was observed that A. muscaria (16-3) and L. laccata (9-12) biosynthesized the highest activity of enzymes in contrast to the strains of S. bovinus and S. luteus. The mycelium of T. harzianum turned out to be the best substrate for the induction of beta-1,3-glucanases and beta-glucosidases for both strains of L. laccata, although the difference in the induction of chitinases in the presence of mycelia of different species of Trichoderma was not indicated.

Studies were carried out on the utilization of different sugars (glucose, fructose, arabinose, xylose, sucrose) and organic acids (acetic, citric, fumaric, propionic, succinic) by fast and slow growing bacteria isolated from the roots of pine seedlings (P. silvestris L.) inoculated with root-free, rhizosphere and mycorrhizosphere soil from nursery and mature pine forest. Sucrose among sugars and propionic acid among organic acids were the less frequently utilized compounds. Sugars were better carbon sources than organic acids. Proportion of isolates utilizing respective sugars or organic acids was, in general, significantly higher among fast growing bacteria as compared with slow growing ones. No significant differences in number of strains assimilating the appropiate sugars depending on their original habitat or kind of soil were observed. Such differences were noted for utilization of some organic acids. 3-factor ANOVA confirmed that the growth speed of bacteria at the moment of their isolation had the strongest effect on utilization of the compounds studied.

Subsurface bacterial growth occurred in an N-free medium inoculated with interior tissues of big non-mycorrhizal roots (7 to 8 mm diameter) of 15-20 years-old Scots pine (Pinus sylvestris L.) growing on sand dunes at the Baltic Sea of Poland. The bacteria were not N2 fixers as determined by the acetylene reduction method. Light microscopic and scanning electron microscopic observations revealed massive bacterial clusters residing in the cortical cells underlying epidermis and parenchyma. The bacteria produced yellow-green pigments on King's medium, which fluoresced under ultraviolet (UV) irradiation at 366 nm wavelength, and could be a siderophore-producing Pseudomonas.

Studies were carried out on the effect of bacteria: Arthrobacter globiformis, Bacillus subtilis and Pseudomonas fluorescens on biomass production by three important ectomycorrhizal fungi: Laccaria laccata, Hebeloma crustuliniforme and Rhizopogon vinicolor in media of different composition. It was shown that bacteria stimulated, inhibited or did not affect significantly the biomass production by mycorrhizal fungi. 3-factor ANOVA have shown that although effect of bacteria was statistically significant (p < or = 0.05), composition of medium and its pH affected mycelial growth stronger than bacteria.

Gibberellin-like substances were found to be produced by fungi isolated from mycorrhizae of pine. Among the isolates studied gibberellin-like substances producers were most numerous among the Basidiomycetes forming ectotrophic mycorrhiza and among non-sporulating fungi forming no mycorrhiza. In most strains the gibberellin-like subtances were elaborated after 10--20 days of incubation. The Rf values of the gibberellin-like compounds were different in various strains, but in most of them substances showing gibberellin activity appeared on the chromatograms run with benzene, acetic acid (10:3 v/v) at Rf 0.2--0.6.

Studies on free amino acids production by five species of ectomycorrhizal fungi (Amanita muscaria, Suillus granulatus, Suillus luteus, Suillus bovinus and Rhizopogon luteolus) show that all the fungi produced mainly: glutamic acid, leucine, lysine, ornithine, arginine and an unidentified ninhydrin-positive compound X3. Both the quality and quantity of amino acids released was different in the fungal species studied. The predominant amino acids in post-culture liquids in general did not exceed 1.5 micrograms/mg dry mass.