Soil mycoflora from the Dead Sea Oases of Ein Gedi and Einot Zuqim (Israel)

Samples were taken from the top 10 cm of soils from 24 points in the Ein Gedi area. Among 329 isolates, 142 species were identified: 11 genera of ascomycetes, one genus of coelomycetes, 28 genera of hyphomycetes, 7 genera of zygomycetes and one yeast, in addition to some unidentified basidiomycetes. The hyphomycetes were represented by 17 dematiaceous, 9 mucedinaceous and two tuberculariaceous. Melanconiaceous and stilbellaceous genera were not found. Two new varieties of Microascus recently described were reisolated. No strict thermophiles or halophiles were obtained. There is apparently no very characteristic or specific fungal flora of the Dead Sea Oases although it was different from that found in the desert soil surrounding this area.     

Biodiversity of freshwater fungi

There are more than 600 species of freshwater fungi with more known from temperate, as compared to tropical regions. These includeca 340 ascomycetes, 300 deuteromycetes, and a number of lower fungi which are not discussed here.Aniptodera, Annulatascus, Massarina, Ophioceras andPseudohalonectria are common freshwater ascomycetes, which appear to be well adapted for this lifestyle either in their ascospore types or their competitive-degradative characters. The most common genera of wood-inhabiting deuteromycetes includeCancellidium, Dactylaria, Dictyosporium andHelicomyces. They are categorized into four groups depending on their form and life style: the ingoldian hyphomycetes; the aero-aquatic hyphomycetes; the terrestrial-aquatic hyphomycetes; and the submerged-aquatic hyphomycetes. The adaptations of aquatic fungi for their dispersal and subsequent attachment to new substrates are discussed.     

New sources of cytochalasins A and B from dematiaceous hyphomycetes

One hundred isolates of 27 species belonging to 13 genera of dematiaceous hyphomycetes were screened for production of cytochalasins A and B. Most of these isolates (94) were obtained from Assiut University Culture Collection, Botany Department, Faculty of Science, Assiut University, Egypt; three isolates from CBS, The Netherlands; two isolates from DSM, Germany; and one isolate from IMI, UK. The results revealed that 10 isolates of six species representing five genera of fungi produced cytochalasins A and/or B. These species are Alternaria chlamydospora, Cochliobolus spicifer, Diplococcum spicatum, Phoma herbarum, Phoma multipara and Setosphaeria rostrata. This is the first report for the production of cytochalasins A and/or B by these species of dematiaceous hyphomycetes.     

Primo contributo alla conoscenza di alcuni ifali demaziacei del Sahara algerino

Abstract

First contribution to the knowledge of some dematiaceous hyphomycetes of algerian Sahara.—Nine dematiaceous hyphomycetes, found in the algerian Sahara, near the Ouarglà Oasis, are here described. Three are reported as new species and two as new records for the desertic provenance.     

Photosynthetic Electron Transport During Senescence of the Primary Leaves of Phaseolus vulgaris L.: II. THE ACTIVITY OF PHOTOSYSTEMS ONE AND TWO, AND A NOTE ON THE SITE OF REDUCTION OF FERRICYANIDE

The activity of photosystems one and two (PS I and PS II) wasmeasured in chloroplasts isolated from the primary leaves ofPhaseolus vulgaris. During foliar senescence, the rates of electrontransport through PS I and PS II declined by approximately 25%and 33% respectively. These losses of activity could not accountfor the decrease of 80% in the rate of coupled, non-cyclic electrontransport during senescence. It is therefore suggested thatan impairment of electron flow between the photosystems limitednon-cyclic electron transport in chloroplasts from older leaves.In this study the activity of PS II was measured using oxidizedp-phenylenediamine as the electron acceptor, and trifluralinas an inhibitor of electron transport between PS II and PS I.In chloroplasts from young leaves the reduction of ferricyanidewas a measure of non-cyclic electron transport, but in preparationsfrom older leaves ferricyanide received a large proportion ofelectrons from PS II.     

Male accessory gland secretory proteins in nasuta subgroup of Drosophila: nature and SDS-PAGE patterns

Male accessory gland secretory proteins in seven members of Drosophila nasuta subgroup were analyzed by SDS-PAGE in combination with different staining techniques such as CBB-R250, Silver, PAS, PAS-silver and zinc-imidazole reverse staining. Based on coomassie blue patterns the protein fractions could be classified in to 3 major groups namely group I, group II as well as group III; with high molecular weight fractions falling into group I and low molecular weight fractions into group III. All the three groups of fractions are post-translationally modified by way of glycosylation and group III fractions are found to be highly glycosylated. Fractions of groups I and II when localized with silver stain and group III fractions when localized with PAS-silver stain appear yellow; suggesting that they are sialoglycoproteins. A 40 kD fraction of group II shows differential staining property with zinc-imidazole stain in closely related species namely D. n. nasuta and D. n. albomicans. Analysis of this protein fraction in F1 males of an interspecific cross revealed that it is synthesized by X-chromosomal gene.     

Genotypic differences in branching pattern and fruiting habit in common walnut (Juglans regia L.)

Architectural analysis of 840 Slovenian walnut (Juglans regia L.) genotypes was performed to determine the most typical and frequent morphological types and to evaluate their vegetative and generative potential. Four branching and fruiting patterns (I-IV) were detected. A 3-year-old fruiting branch, consisting of a 3-year-old shoot plus corresponding 2-year-old and 1-year-old shoots, was used as a structural unit for quantitative analysis. In the intermediate fruit-bearing types with mesotonic and acrotonic branching pattern (types II and III), the total lengths of 3-, 2- and 1-year-old shoots were 385 and 380 cm, respectively, compared with 275 and 253 cm in the terminal and lateral-fruiting types (types I and IV). In type I, 1-year-old shoots had significantly fewer nodes than in other types. In addition, they had a thinner basal diameter than types III and IV, and their angles were the most erect (39 degrees ). Only 0.4 out of 3.6 1-year-old shoots were flowering with one mixed bud with 1.9 female flowers. In type IV, 2-year-old shoots had significantly more nodes and a larger basal diameter than other types. One-year-old shoots in type IV are thicker than those in other types. Ratios between the number of flowering and the total number of 1-year-old shoots were 0.7 in type IV, 0.6 in type III, 0.5 in type II and 0.1 in type I. On 1-year-old shoots in type IV, 1.7 mixed buds with a mean of three female inflorescences per bud were counted. Consequently, the generative potential is highest in type IV and lowest in type I. In types II and III, growth and the ability to bear fruits are more balanced.     

Superoxide dismutases of chestnut leaves, Castanea sativa: Characterization and study of their involvement in natural leaf senescence

Superoxide dismutases (SOD; EC 1.15.1.1) in chestnut ( Castanea sativa Mill., cv. 431) leaves were characterized by native polyacrylamide gel electrophoresis. The three molecular forms of SOD were distinguished from each other by their different sensitivity to cyanide and H₂O₂ Three CuZn-containing SODs were detected (CuZn-SOD I, II. and III), and all the isozymes had a molecular mass of 33 kDa. CuZn-SOD III was the most abundant isozyme. whereas CuZn-SOD II was present in a minor amount. In leaves showing typical symptoms of senescence increases of 2.5-. 7- and 4-fold in the specific activities of CuZn-SODs I, II, and III. respectively, were found. In addition, the pattern of the three isozymes was modified by the age of leaves, a rise in the CuZn-SOD II and a decrease in the CuZn-SOD 1 percentages being found in senescent leaves compared to green leaves. As to other activated oxygen-related enzymes, an increase in the superoxide-generating xanthine oxidase activity and a decline in both catalase and peroxidase activities during natural senescence of chestnut leaves were observed. Results obtained suggest that in natural senescence of chestnut leaves activated oxygen species are involved, and an overproduction of hydrogen peroxide and superoxide radicals probably takes place.     

Modification of flag leaf senescence and yield characters in barley (Hordeum vulgare L.) by gibberellic acid and kinetin

Barley plants (Hordeum vulgare L.) received foliar applications of 10^?4 M gibberellic acid (GA₃) and Kinetin (KN) individually and in combination at one or more of three growth stages: flag leaf appearance (I), ear emergence (II), and the first stage of senescence initiation in the flag leaf (III). Both plant growth regulators (PGR) hastened onset of senescence when sprayed at Stage I and/or Stage II. Treatment at Stage III, either alone or in combination with treatments at the other stages, tended to postpone senescence. Yield components also showed stage-dependent response: Stage I treatment increased the formation of total and bearing tillers, and Stage III treatment improved grain number and weight. However, while GA₃ proved more effective than KN, the two together acted antagonistically.     

Leaf Abscission in Varieties of Phaseolus vulgaris (L. ) and Glycine max (L. ) Merrill/emdash a--Correlation with Propensity to Produce Adventitious Roots

In field trials of Phaseolus vulgaris large differences wereobserved between varieties in the rate at which the leaves abscised.Similar differences were found in the rate of decline of thechlorophyll content of excised leaf discs. A grafting experimentshowed that the differences in leaf abscission depended on thegenotype of the scion and on that of the rootstock. Scion andstock effects of each genotype were similar, and additive. Rootstock/scioncombinations which conferred enhanced leaf retention producedgreater yields of seed and of seed nitrogen. When shoots ofdelayed-senescence genotypes of P. vulgaris were held in waterthey produced more adventitious roots than did shoots of rapid-senescencegenotypes. This relationship between senescence pattern andadventitious rooting was also observed among varieties of Glycinemax, and between isogenic lines of G. max differing in the leafabscission alleles Ab/ab. These results are discussed in relationto current theories of leaf senescence, abscission, and theproduction of yield.     

Spectral fluorescence signatures in the characterization of phytoplankton community composition

Fluorescence spectral signatures from 28 algal cultures aredescribed.The cultures are split into four groups accordingto their accessory pigments. Phycocyanin and phycoerythrin,characteristic pigments of cyanobacteria, form groups I andII. The characteristic pigment found in group III is chlorophyllb (green and rasinophyte algae) and in group IV it is chlorophyllc (diatoms, dinophytes and some other algae).This preliminarycatalogue of spectral signatures was used to characterize fivenatural phytoplankton communities from brackish water environmentsas a comparison with phytoplankton species found in the samples.Accessory pigments such as phycocyanin and phycoerythrin, characterizinggroups I and II, can be used for identification without confusion.Distinguishing between groups III and IV is more complicated,because their accessory pigments do not have their own fluorescence.These groups can be characterized by increased fluorescenceof chlorophyll a induced by energy excited through chlorophyllb and c. The possibilities of applying the spectral fluorescencesignatures approach to the characterization of natural communitiesare discussed.     

The Effects of Corticoptropin-Releasing Factor and the Urocortins on Striatal Dopamine Release Induced by Electrical Stimulation—An in vitro Superfusion Study

The members of the CRF peptide family, corticotropin-releasing factor (CRF), urocortin I (Ucn I), urocortin II (Ucn II) and urocortin III (Ucn III) coordinate endocrine and behavioral responses to stress. CRF has also been demonstrated to stimulate dopamine (DA) synthesis.In our study, a superfusion system was used to investigate the effects of this peptide family on striatal DA release following electrical stimulation. The involvement of the CRF receptors was studied by pretreatment of rat striatal slices with selective CRF antagonists. CRF and Ucn I increased the release of [³H]DA while Ucn II and Ucn III were ineffective. The CRFR1 antagonist antalarmin inhibited the [³H]DA release induced by electrical stimulation and enhanced by CRF and Ucn I. The CRFR2 antagonist astressin-2B was ineffective.These results suggest that CRF and Ucn I mediate DA release through the activation of CRFR1. Ucn II and Ucn III are not involved in this process.Special Issue Dedicated to Miklós Palkovits.     

Production of cytochalasins C,D & E from dematiaceous hyphomycetes

One hundred isolates of 27 species belonging to 13 genera of dematiaceous hyphomycetes were screened for production of cytochalasins C, D and E. Only two isolates ofBipolaris neergaardii and one isolate ofPhoma herbarum produced cytochalasins C and D. Also, cytochalasin E was produced by two isolates ofAlternaria chlamydospora, and one isolate ofCochliobolus tuberculatus. This is the first report about the production of cytochalasins C, D and E by these species of dematiaceous hyphomycetes.     

Aquatic hyphomycetes of a sulphur spring

Aquatic hyphomycetes of a sulphur spring in the Western Ghat region of Karnataka were investigated by the following methods: leaf litter observations, water filtration, analysis of natural and induced foam. The samples were collected and studied from three sites, the spring proper (site I), the connecting region of the spring and the rivulet (site II) and the spot where the spring joins the rivulet (site III). The number of species of hyphomycetes encountered at the three sites were 1, 14 and 20, respectively. The sulphide content of the spring ranged between 0.1–3.1 mg l^–1 and the temperature between 26.5–36.5 °C. In another experiment submerged coffee leaves from a fresh water stream were collected and incubated in spring water, stream water and well water at different temperatures (16–40 °C). A maximum of 18 species of hyphomycetes sporulated at 22 °C followed by 17 species at 28 °C, irrespective of the source of water in which the leaves were incubated. Based on these studies, we conclude that the presence of only one species in the spring proper (site I) was not due to the higher sulphide content, but to the high temperature.     

Modification of flag leaf senescence and yield characters in barley (Hordeum vulgare L.) by gibberellic acid and kinetin

Barley plants (Hordeum vulgare L.) received foliar applications of 10^–4 M gibberellic acid (GA₃) and Kinetin (KN) individually and in combination at one or more of three growth stages: flag leaf appearance (I), ear emergence (II), and the first stage of senescence initiation in the flag leaf (III). Both plant growth regulators (PGR) hastened onset of senescence when sprayed at Stage I and/or Stage II. Treatment at Stage III, either alone or in combination with treatments at the other stages, tended to postpone senescence. Yield components also showed stage-dependent response: Stage I treatment increased the formation of total and bearing tillers, and Stage III treatment improved grain number and weight. However, while GA₃ proved more effective than KN, the two together acted antagonistically.     

柴达木盆地中西部土壤中暗色丝孢菌群落多样性分析

从柴达木盆地中西部采集土样59份,涵盖的生态类型有:沙漠、戈壁、湿地、小镇-绿洲等。分离获得暗色丝孢菌108株,经鉴定分属于15属。利用种群优势度、Shannon-Wiener多样性指数、物种均匀度、生态位宽度四项指数,对柴达木盆地中西部不同生境土壤中的有关暗色丝孢菌物种(属级)进行物种多样性分析。结果表明,该地区土壤中暗色丝孢菌的物种优势度存在明显差异:沙漠生境中,链格孢属Alternaria和细基格孢属Ulocladium真菌优势度较高;戈壁生境中,单格孢属Monodictys真菌的优势度最高;湿地和小镇-绿洲生境中,则分别以瓶霉属Phialophora和枝孢属Cladosporium真菌占优势。在小镇-绿洲生境中,土壤暗色丝孢菌的Shannon-Wiener多样性指数最高,均匀度较低;而在沙漠和戈壁生境中多样性指数明显较低,而物种的均匀度较高。在上述四类生境中,链格孢属Alternaria和细基格孢属Ulocladium真菌具有较宽的生态位,为广适性物种;而平脐蠕孢属Bipolaris、卷旋孢属Cirrenaria、弯孢属Curvularia、矛束霉属Doratomyces、粘束孢属Graphium、漆斑霉属Myrothecium、齿梗孢属Scolecobasidium、帚霉属Scopulariopsis、节隔孢属Scytalidium和葡萄穂霉属Stachybotrys10个属真菌的生态位较窄,为狭适性物种。     

Changes in Chlorophyll Content and Organization During Senescence of the Primary Leaves of Phaseolus vulgaris L. in Relation to Photosynthetic Electron Transport

A large decrease was observed in the chlorophyll content ofthe primary leaves of Phaseolus vulgaris during senescence.Chloroplasts isolated from mature and senescent leaves gavevery similar light saturation curves for electron transportreactions involving either PS I or PS II, indicating that theaverage number of chlorophyll molecules associated with eachreaction centre did not change during senescence. It is concludedthat the reaction centres ceased to function at the same timeas, or perhaps before, their antenna chlorophylls were lostfrom the thylakoid membrane, and that the percentage decreasein the number of functional reaction centres per leaf was atleast as great as the percentage decrease in the leaf chlorophyllcontent. The chlorophyll-protein composition of thylakoid membrane preparationswas examined by electrophoresis of samples treated with sodiumdodecyl sulphate. In older leaves a smaller proportion of thechlorophyll applied to polyacrylamide gels was associated withthe P700- chlorophyll a-protein complex. There was also a declinein emission at 734 nm in the 77 °K fluorescence spectrumof intact leaf tissue during senescence. These results indicatethat older leaves contained a smaller proportion of chlorophyllsassociated with PS I, and this is consistent with the decreaseobserved in the leaf chlorophyll a/b ratio during senescence.The effect of these changes in chlorophyll content on the capacityof the chloroplast to carry out photosynthetic electron transportis discussed.     

Screening for a “new” enzyme in nature: Haloperoxidase production by Death Valley dematiaceous hyphomycetes

Haloperoxidases are enzymes that have the ability to halogenate a broad range of substrates [10]. To find a biologically produced haloperoxidase that could function at a pH greater than 3.0 and at a temperature greater than 19°C, dematiaceous hyphomycetes were isolated from the Death Valley desert and screened for their ability to produce such an enzyme. A qualitative assay using bromophenol red was employed in situ over a 12-day fermentation period. Several dematiaceous hyphomycetes, such asDreschlera haloides andUlocladium chartarum, produced haloperoxidases that were active in broth culture at 19, 25, and 34°C at pH 7.0 and 8.0.     

Interstrain inhibition in the sweet potato pathogen Streptomyces ipomoeae: purification and characterization of a highly specific bacteriocin and cloning of its structural gene

Strains of the sweet potato soil rot pathogen Streptomyces ipomoeae had previously been divided into three groups based on their ability to inhibit one another during pairwise cocultivation. While group I strains are not antagonistic to members of the other groups, group II and group III strains produce separate substances that are inhibitory to strains outside their respective cognate groups. Here, we purified the group III inhibitory substance from the culture supernatant of a representative strain and found that it consists of a single 10-kDa cationic protein which is bacteriolytic for S. ipomoeae group I and II strains but which showed no inhibitory function against other streptomycetes or other bacterial genera tested. The structural gene for the inhibitor was cloned from a chromosomal library of the producing strain, and while the gene sequence revealed that the inhibitor is initially made in a larger precursor form, the deduced mature protein showed no significant homology to other known proteins. Our results demonstrate that S. ipomoeae group III inhibitory activity is manifested in the form of a highly specific, potentially novel bacteriocin, which we have designated ipomicin.