The fine structure of the basidiospores of Pluteus cervinus and Agrocybe acericola is described using TEM, SEM, and light microscopy.The basidiospore wall of Pluteus cervinus is bipartite. No surface ornamentation or germ pore is present. The protoplasm is surrounded by a typical membrane which lacks distinct invaginations. Spores contain much stored lipid, which is centrally located. Spores are uninucleated with the nucleus closely appressed to the cell membrane, located at the base of the spore near the hilar appendage. Mitochondria with few, well-delineated plate-like cristae are present. Endoplasmic reticulum (ER) is scant. Ribosomes occur regularly attached to the ER and outer mitochondrial membrane, as well as being densely packed throughout the cytoplasm. Various sized vacuoles containing an electron dense material are present. Microbody-like organelles are observed, which are probably glyoxysomes, since assays of malate synthase, a maker enzyme of the glyoxylate cycle, are positive.The basidiospore wall of Agrocybe acericola is composed of two distinct layers, both layers are continuous around the spores, at the germ pore the outer wall is very thin and the inner wall becomes thicker. The plasma membrane is appressed to inner wall and lacks invaginations. The protoplasm is densely packed with small granules, probably ribosomes and/or glycogen. Spores contain very little lipid with bipolar distribution. Mitochondria are well-defined and distributed in cytoplasm. Spores are binucleate with the two nuclei lying on a line nearly perpendicular to the long axis of the cell. Various size single membrane-bound vacuoles are widely distributed in the cytoplasm. These vacuoles were shown to contain acid phosphatase indicating lysosomal activity. Microbodies, probably glyoxysomes, are observed. Malate synthase assays are positive indicating the occurrence of the glyoxylate cycle. / Department of Biology

Typescript. / Thesis (Ph. D.)--University of Hawaii at Manoa, 1984. / Bibliography: leaves [82]-88. / Photocopy. / Microfilm. / viii, 88 leaves, bound ill. 29 cm

The phototactic zoospores of Nowakowskiella elegans (Nowak.) Schroeter and Cladochytrium replicatum Karling are similar in their ultrastructure and typical of the revised Chytridiales (Barr, 1980, Can. J. Bot. 58: 2380-2394). For a carbon source both species utilize cellulose, D-cellobiose, D-glucose, D-xylose, and D-mannose. Several sources of organic nitrogen, and inorganic nitrate, and ammonium are utilized. Both species are deficient for thiamine. Germination of the zoospore cyst in both cases is exogenous, and daughter nuclei migrate and divide independently in the developing rhizomycelium. Mitosis is intranuclear. Zoospore discharge in N. elegans is operculate and vesicular, and in C. replicatum inoperculate and vesicular. Resting spores are formed asexually in C. replicatum and sexually in N. elegans. Meiosis in N. elegans is described. Nowakowskiella and Cladochytrium are retained in the family Cladochytriaceae.

No description available.

Thesis (MSc)--University of Stellenbosch, 2006. / ENGLISH ABSTRACT: It is known that many hyphomycetous fungi are dispersed by wind, water and insects. However, very little is known about how these fungi may differ from each other regarding their ability to be disseminated by different environmental vectors. Consequently, to obtain an indication of the primary means of spore dispersal employed by representatives of the genera Acremonium, Aspergillus and Penicillium, isolated from soil and indoor environments, we monitored spore liberation of cultures representing these genera in an airflow cell. The experimental data obtained, of plate counts conducted of the air at the outlet of the airflow cell, were subjected to an appropriate analysis of variance (ANOVA), using SAS statistical software. Intraspecific differences occurred regarding aerial spore release. Under humid conditions, however, Penicillium species were more successful in releasing their spores than Aspergillus and the Acremonium strain. Under desiccated conditions the Aspergillus took longer to release their spores than representatives of Acremonium and Penicillium. The taxa that were investigated did not differ from each other regarding the release of spores in physiological salt solution (PSS). Although not proven, indications are that water may act as an important dispersion agent for these fungi, because washing of cultures with PSS resulted in all cases in an immediate massive release of colony forming units. Subsequently, using standard plate count techniques, conidial adhesion of the fungi mentioned above to synthetic membranes, leaf cuttings and insect exoskeletons differing in hydrophobicity and electrostatic charge were investigated. We found that the different genera showed different adhesion profiles for the series of test surfaces, indicating differences in physico-chemical characteristics of the fungal spore surfaces. In general, the Penicillium strains showed a greater ability to adhere to the test surfaces, than the aspergilli, while the representative of Acremonium showed the least adherence. No significant difference in the percentage spore adhesion was found between hydrophobic and hydrophilic materials. Furthermore, evidence was uncovered supporting the contention that, under dry conditions, electrostatic surface charges play a role in the adherence of fungal spores to surfaces, because adherence was positively correlated (Correlation coefficient = 0.70898, p = 0.001) to positive electrostatic charges on the lamellar surfaces. In the next part of the study, standard plate count methods were used to determine the relative adhesion of the above mentioned hyphomycetous fungi, as well as a polyphyletic group of yeasts, to the test surfaces submerged in 10 mM sodium phosphate buffer (pH 7.0). As was found with the experiments with the dry surfaces, both intraspecific and intergenus differences were uncovered. Overall, the fungi adhered better to hydrophilic surfaces than to hydrophobic surfaces. This indicated that the fungal surfaces were covered with relatively hydrophilic compounds such as carbohydrates. Subsequently, it was demonstrated that all the fungi adhered to plasma membrane glycoprotein coated polystyrene and the presence of fungal carbohydrates on the surfaces of the fungal propagules was confirmed using epi-fluorescence microscopy. Differences in the strategy of the fungal genera to release their airborne spores, as well as differences in their adhesion profiles for the series of test materials, may be indicative of a unique environmental niche for each genus. In future, this phenomenon should be investigated further. / AFRIKAANSE OPSOMMING: Hifomisete fungi is daarvoor bekend om te versprei deur middel van wind, water, en insek vektore. Maar nietemin, daar is bykans geen kennis m.b.t. hoe hierdie fungi van mekaar verskil t.o.v. hul vermoë om versprei te word deur omgewings vektore nie. Gevolglik was spoorvrystelling van kulture, verteenwoordigend van die genera Acremonium, Aspergillus en Penicillium gemoniteer om ‘n aanduiding te kry van primêre wyse van spoorverspreiding waardeur verteenwoordigers van die onderskeie genera ingespan word. Eksperimentele data ingewin, vanaf plaat tellings wat uitgevoer was op lug afkomstig vanuit die uitlaat-klep van die lugvloei kapsule, was onderwerp aan ‘n toepaslike analise van afwyking (ANOVA), deur gebruik te maak van ‘n SAS statistiese pakket. Intraspesie verskille is waargeneem t.o.v. lug spoorvrystelling. Desnieteenstaande was Penicillium meer suksesvol onder vogtige kondisies t.o.v. spoorvrystelling in vergelyking met Aspergillus en die Acremonium stam. Onder droë kondisies het verteenwoordigers van Aspergillus langer geneem om hul spore vry te stel as verteenwoordigers van onderskeidelik, Penicillium en Acremonium. Geen verskille was waargeneem m.b.t. spoorvrystelling in fisiologiese soutoplossing (FSO) tussen die verskillende filogenetiese stamme nie. Alhoewel dit nie bewys is nie, wil dit voorkom asof water as belangrike verspreidingsagent van die betrokke fungi dien, aangesien die spoel van kulture met FSO tot ‘n oombliklike enorme vrystelling van kolonie-vormende eenhede gelei het. Gevolglik, deur gebruik te maak van standaard plaattellings tegnieke, was spoor aanhegting van bogenoemde fungi aan sintetiese membrane, blaar snitte en insek eksoskelette wat verskil in terme van hidrofobisiteit en elektriese lading, ondersoek. Daar was gevind dat die aanhegtingsprofiele m.b.t. hierdie reeks toetsoppervlaktes van die verskillende genera verskil, wat op sigself ‘n aanduiding was van verskille in fisieschemiese eienskappe van die swamspoor oppervlaktes. Penicillium stamme het ‘n hoër aanhegtings vermoë aan die toetsoppervlaktes getoon as die aspergilli, terwyl die verteenwoordiger van Acremonium die laagste aanhegting getoon het. Geen betekenisvolle verskille i.t.v. persentasie spoor aanhegting was gevind tussen hidrofobiese en hidrofiliese oppervlakte nie. Daarbenewens was die argument dat spoorvrystelling onder droë kondisies beïnvloed word deur elektrostatiese oppervlak ladings, bevestig deur ons bevindinge, want aanhegting het positief gekoreleer (Korrelasie koëffisient = 0.70898, p = 0.001) met positiewe ladings op die oppervlaktes. ‘n Standaard plaattellingstegniek was aangewend in die volgende fasset van die studie om die relatiewe aanhegting van bogenoemde hifomisete fungi, sowel as ‘n polifilitiese groep giste aan die toetsoppervlaktes, gedompel in 10 mM natrium fosfaat buffer (pH 7.0) vas te stel. Intraspesie en intragenus verskille was weereens waargeneem, net soos in die geval van die eksperimente met die droë oppervlakte. In die algemeen het die swamme baie beter geheg aan hidrofiliese oppervlaktes in vergelyking met hidrofobiese oppervlakte. Dit was ‘n aanduiding dat die swamspoor oppervlaktes bedek was met relatiewe hidrofiliese verbindings bv. koolhidrate. Verder was daar bewys dat alle swamme ingesluit in hierdie studie die vermoë het om plasmamembraan glikoproteïn bedekte polistireen te bind, en gevolglik was die teenwoordigheid van van koolhidrate op die swamspore bevestig m.b.v epi-fluoresensie mikroskopie. Verskille in die strategie van swamme om spore in die lug vry te stel, sowel as verskille in die aanhegtingsprofiele vir ‘n reeks toetsmateriale, mag net ‘n aanduiding wees van ‘n unieke omgewings nis vir elke genus wat in hierdie studie ondersoek is. Hierdie verskynsel moet dus in die nabye toekoms nagevors word.

No description available.

An algorithmic method for the recognition of fungal spore cells in microscopic images, as well as its development and its origin, are described and demonstrated. The process is designed for a machine vision project which automatically identifies fungal spores within field samples for epidemiological simulation models. The method consists of a three-pass system that successfully recognizes spores in any position and which is tolerant of occlusion. / The algorithm, as implemented, demonstrated an accuracy of $ pm$5.3% on low quality images which is less than the assumed error of humans performing the same task. The processing speed also compared favorably with the performance of humans. / The method developed presents a framework of description that, through the first two passes, highlights certain distinctive aspects within an image. Those highlighted aspects are then recognized by the third pass. The system is loosely based on biological vision, is extremely versatile and could be adapted for the recognition of virtually any object in a digitized image.

No description available.

Morphologically and anatomically the Russulales (Basidiomycetes) are a homogeneous group of higher fungi, which contains both ballistosporic and statismosporic, agaricoid and gasteroid taxa. Spore symmetry and ability to forcibly discharge spores are therefore fundamental systematic characteristics in the Russulales. Ballistosporic and statismosporic basidiosporogenesis however, has not been critically compared. Early and late basidiosporogenesis, spore-wall tegumentation, and differentiation of the hilar appendix were ultrastructurally characterized in species selected from eight genera of agaricoid and gasteroid Russulales including: Russula, Lactarius, Macowanites, Arcangeliella, Elasmomyces, Gymnomyces, Martellia, and Zelleromyces. Six spore-wall layers are present in developing spores in all genera. Two wall layers are associated with an evanescent pellicle and four wall layers are derived from the sterigma and young spore. The amyloid portion of the spore wall in the Russulales is an electron-translucent wall layer covered by an electron-dense surface layer. Ontogeny of spore-wall ornamentation is similar in all genera, however diversity in the degree of ornamentation and amyloidity results from differentiation and intermixing of the two outermost enduring wall layers. Establishment of early spore asymmetry in both ballistosporic- and statismosporic-heterotropic basidiospores is highly correlated with the presence of a hilar appendix body. Observation of a demarcated cytoplasmic region, reminiscent of the hilar appendix body, in asymmetric sterigmata of orthotropic Russulales suggests that basidiospore morphology and symmetry are variable features in the Russulales. Late spore development subsequent to nuclear migration is similar in orthotropic and heterotropic Russulales. Orthotropic basidiospores appear to be released from sterigmata upon breakdown of the sterigmata. Heterotropic basidiospores are released while sterigmata are intact. Plugging layers develop in both the sterigma and in the hilar appendix. The hilar appendix plugging material appears to be produced by a plug-forming body which originates in the spore, and possibly controls liquid droplet formation during ballistosporic discharge. Ballistosporic discharge appears to be a conservative phenomenon in most Basidiomycetes resulting from a prescribed sequence of biochemical and developmental processes. The use of ballistospory and statismospory in distinguishing families and genera must be re-evaluated in the Russulales. Recognition of the Lactariaceae and Russulaceae is discussed. / Ph. D.