On the taxonomy of trichophyton gallinae

Summary Multiseptate macroconidia with round end cells are recovered from a strain ofTrichophyton gallinae under the effect of CO₂. They possess an elongated form with thin and smooth walls. Their pediculation is not clearly manifested. They display a morphology similiar to the macroconidia ofTrichophyton quinckeanum, Trichophyton mégnini, Trichophyton rubrum, Trichophyton violaceum, Trichophyton equinum andTrichophyton verrucosum, differing from those ofCtenomyces.Dedicated to ProfessorTibor Benedek on the occasion of his 70th birthday.     

On the morphology of trichophyton quinckeanum

Summary The cultivation of four old non-sporulating strains ofTrichophyton quinckeanum on solid nutrient medium with 15% CO₂ (Sabouraud dextrose agar) gave an increased production of macroconidia. The macroconidia are multilocular with smooth walls. It is believed that the polymorphism of the macroconidia — some with pointed tip and other with round terminal cell — is characteristic of the species and has a taxonomic significance. Macroconidia with a pointed end cell are not of theMicrosporon type, since they have smooth walls and are not pointed on both ends Filiform appendages from the terminal cell occur regularly. Small and large macroconidia were seen. The microconidia are pyriform or elongated. No rounded microconidia withBotrytis type of arrangement were observed. The so-calledT. niveum is probably identical withT. quinckeannum.Together with the characteristics of the species as a parasite it is to be concluded thatT. quinckeanum is a peculiar dermatophyte species, corresponding toQuincke's -Pilz, but cannot be assimilated by the group ofT. mentagrophytes (Ctenomyces s. microides).     

Morphological and cytological observations on conidial formation of the genera Epidermophyton and Microsporon

Some morphological and cytological aspects ofEpidermophyton andMicrosporon were studied according to the classification of the Fungi Imperfecti suggested byHughes.It was found that origin of macroconidia in the genusEpidermophyton is quite different from that of the genusMicrosporon. The macroconidia of the speciesMicrosporon gypseum, M. fulvum andM. canis presented only pseudosepta; true septa were present inM. cookei, M. audouinii andM. vanbreuseghemii. On the basis of the morphological features of macroconidia a simple analytical key for the species ofMicrosporon most frequently isolated in Italy is proposed.These studies were supported by grant of the Consiglio Nazionale delle Ricerche of Italy under contract n.69.01074/115.2798.     

Morphological changes of trichophyton mentagrophytes under the influence of increased carbon dioxide tension

Summary Growth pigment production as well as macroconidia and arthrospore formation ofTrichophyton mentagrophytes are stimulated under the influence of increased carbon dioxide tension. Macroconidia with spirals and pistol forms of macroconidia are observed.The granular form ofT. mentagrophytes displays an asteroid growth (Dextrose agar of Sabouraud) with an ingrowth and elongation of the ray branches in the agar and a decrease of the air-mycelium. The culture completely resembles to those ofT. mentagrophytes varasteroides. The macroconidia appear elongated and they acquire an asteroid arrangement. The less granular strains ofT. mentagrophytes take the appearance ofT. interdigitale type.An analogy is made between these morphogenetic changes under the effect of increased CO₂ tension in vitro and the influence of the animal organism in the evolution of the growth forms of dermatophytes in vivo in the process of their parasitic adaptation.     

Microtubular remnants in macroconidia ofNeurospora crassa benomyl-induced to multipolar germination

Benomyl-treated macroconidia ofNeurospora crassa show, upon immunofluorescent probing, randomly distributed remnants of microtubules in the mother conidium multipolarly protruding germ tubes.     

T. Mentagrophytes with macroconidia and spirals in the peridium of abortive cleistothecia of the type Arthroderma in soils in Bulgaria

Summary In two soil isolates ofT. mentagrophytes we observed an ornament of macroconidia with spirals in the peridium of the cleistothecia of the typeArthroderma. These strains grow more rapidly and are less pigmented thanT. mentagrophytes isolated from pathological lesions. The problem of the phylogenetical importance of this morphogenetic changes in connection with the transition ofT. mentagrophytes from saprophytism into parasitism is discussed.     

Conidiation ofNeurospora crassa in submerged culture without mycelial phase

Summary Conidia ofNeurospora crassa shaken in liquid cultures at 46°C for 15 h and then shifted-down to 25°C germinate directly into conidiophores producing new conidia (macroconidia).     

Preformed messengers inMicrosporum canis macroconidia

Macroconidia ofMicrosporum canis, when placed in a nutrient medium produce germ tubes within 4–6 h. Precursor incorporation studies showed that protein synthesis occurred prior to RNA synthesis. Sucrose density gradient analysis of wet and dry spore extracts revealed the presence of 16 % and 11 % polysomes respectively. The polysomal content increased to about 50% within 15 min of germination. Synthesis of RNA occurred only after 2 h of germination. Pool equilibration of the radioactive precursors was not limiting to these measurements. Polyadenylated RNA was isolated from macroconidia and was found to comprise 2–2.5 % of the total RNA. The poly(A)⁺ RNAs were heterodisperse and translatable in a wheat germ cell free translating system. It was concluded that macroconidia ofMicrosporum canis contain pre-formed mRNA which is translated early in germination     

Lipids associated with microconidial differentiation in a mutant ofNeurospora crassa

Thepeach-fluffy-cot mutant ofNeurospora crassa produces neither macroconidia nor ascospores but does differentiate microconidia after a defined length of time. Changes in the composition of sterols, sterol esters, triglycerides, free fatty acids, and phospholipids were followed during vegetative growth and differentiation of microconidia. The changes in free sterols before and during microconidial differentiation indicate a change in lipid metabolism associated with differentiation. Free sterols and sterol esters accumulated in the developing microconidia, but decreased rapidly during microconidial maturation. The fatty acid components remained relatively unchanged except for a significant increase in linoleic acid. The linoleic acid change might be associated with the development of microconidia or it might simply be a reflection of the NADP-deficiency common in many morphological mutants ofN. crassa.     

Wheat-infectingFusarium species in Poland — their chemotypes and frequencies revealed by PCR assay

ThreeFusarium species:F. graminearum, F. culmorum andF. cerealis were identified in laboratory cultures and in sporodochia from spikelets of scabby wheat. SCAR (sequence characterized amplified region) primers were used to identifyFusarium species and nivalenol (NIV) and deoxynivalenol (DON) chemotypes within species in laboratory cultures and field collected heads harvested in 2006. Results from PCR analyses confirmed preliminary identifications of species on the basis of examination of macroconidia under a light microscope and identification of cultures on agar media. NIV and DON (3Ac-DON and 15Ac-DON) chemotypes were identified using PCR assay. Among samples and isolates ofF. graminearum, the 15Ac-DON chemotype dominated, and among those whereF. culmorum was identified, the 3Ac-DON chemotype prevailed. Only 5 of the 41 isolates ofF. graminearum tested, displayed the NIV chemotype. An increase in the frequency ofF. graminearum and a decrease in the frequency ofF. culmorum were found during 1998 to 2006.     

Computer-aided morphometrical analysis of macroconidia inFusarium sambucinum Fuckel sensu lato strains

Forty-one strains ofFusarium sambucinum Fuckelsensu lato were classified on the basis of morphological data of the macroconidia obtained by automated microscopic image analysis. The classification factors were determined in sixFusarium strains of the sectionDiscolor. The results show the relative homogeneity within the groups proposed by Nirenberg. A remarkable difference could be detected especially between the groupsF. sambucinum, F. torulosum andF. sambucinum sensu lato on the one hand andF. spec nov. on the other.Abbreviations PDA potato dextrose agar - SNA synthetic nutriment agar     

The surface structure of saprophytic and parasitic dermatophyte spores

The surface structure of conidia and arthrospores ofMicrosporon ²)racemosum andTrichophyton winacei is described. Apart fromMicrosporon macroconidia, the spore surfaces displayed little or no ornamentation. The arrangement of verrucae on the surface ofMicrosporon conidia appears to be variable, but may be of little taxonomic importance other than as a characteristic of the genus.

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Zusammenfassung Die Oberflächenstruktur der Konidien und Arthrosporen vonMicrosporon racemosum undTrichophyton erinacei sind beschrieben. Abgesehen von den Makrokonidien vonMicrosporon zeigten die Oberflächen der Sporen geringe oder keine Ornamentation. Die Anordnung der Warzen an der Oberfläche von Makrosporenkonidien erscheint wechselvoll und sie mag von geringer Wichtigkelt sein, außer der Charakterisierung der Gattung.

     

Fusarium crookwellense,a newly isolated fungus from wheat in Japan: Its mycotoxin production and pathogenicity to wheat and barley

Fusarium crookwellense was isolated for the first time in Japan from scabby wheat harvested in Hokkaido in 1991. Four isolates were obtained and examined for their mycological features on culture media, mycotoxin production, and pathogenicity to wheat and barley. The texture of fungal colonies and the morphology of macroconidia on a potato dextrose agar medium were similar to those ofFusarium graminearum. AllF. crookwellense isolates examined produced nivalenol, 4-acetylnivalenol, and zearalenone on rice media at levels ranging from 0.9 to 22.5 µg/g, 0.5 to 25.0 µg/g, and 1.4 to 162.5 µg/g, respectively. All were pathogenic toward the wheat and barley strains tested, and scab symptoms were found on the heads and leaves of plants. This is the first report on domestic isolates ofF. crookwellense from the crop field in Japan.     

Adhesion-reduced mutants and the wild-typeNectria haematococca: An ultrastructural comparison of the macroconidial walls

We examined the macroconidial wall layers of various strains ofNectria haematococca prior to germ tube emergence. Using freeze-substituted cells, the wall ultrastructure of an adhesion-competent wild-type strain was compared with two adhesion-reduced mutants, LE1 and LE2. At 0 h, the freshly harvested macroconidia of all strains had a similar, bilayered wall and were all nonadhesive. After 1 h, wild-type macroconidia were adhesive and their cell walls exhibited two additional layers not present at 0 h: a pellicular third layer and a thick, outermost fourth layer. Material from the fourth layer was apparently discharged into the surrounding medium. In contrast to the wild type, the mutants after 1 h were adhesion-deficient; the outermost wall layers of LE1 and LE2 differed from each other and from the wild type. There were also differences in the wall layers and extracellular matrices between the mutants and the wild type after 3- and 5-h incubations. Plasma membrane invaginations were not observed at 0 h, but were detected in both wild type and mutant macroconidia at 1, 3, and 5 h. The data demonstrate that in macroconidia ofN. haematococca (1) the wall and associated extracellular matrix undergo major morphological changes prior to germ tube emergence and (2) development of adhesiveness is correlated with the appearance of new wall layers.     

<Emphasis Type="Italic">Dwiroopa</Emphasis>, a coelomycetous genus with two species

The coelomycete Dwiroopa was determined to be the correct genus for Harknessia lythri, and a new combination is made for this species. The type species of Dwiroopa, D. ramya, is redescribed and illustrated based on the type specimen for which a lectotype is designated. A key to the two species of Dwiroopa is presented along with a discussion of their similarities and differences. The genus Dwiroopa is distinguished from Harknessia by conidial characteristics. In Dwiroopa the macroconidia have widely spaced, longitudinal slits around the conidia and lack a basal appendage, whereas in Harknessia the macroconidia are smooth or have closely spaced, longitudinal slits on only one side of the conidia and often have a true basal appendage. Both Dwiroopa and Harknessia are included in the Diaporthales.     

Isolation of aCandida utilis variant by using a nitrogen-limited continuous culture

During continuous culture ofCandida utilis the appearance of a morphologic variant yeast was detected. The new microorganism developed systematically whenever it was changed from normal to stressed propagation conditions. A simple system was used for the isolation of the yeast variant, which was defective in cellular division and showed improved kinetic parameters and oxygen uptake rate. An asynchronic nitrogen-limited continuous culture ofCandida utilis allowed us to enrich the population in the chemostat with the modified yeast and isolate it in a defined medium. Assimilation and fermentation tests indicated it to be a variant ofCandida utilis that showed stable morphologic and physiologic differences with the parental yeast.Candida utilis growing in this nitrogen-limited continuous culture also showed a high mutation rate.     

A NEW FUNGUS ON CYPERUS IRIA

Thind , K. S., and G. S. Rawla . (Panjab U., Chandigarh, India.) A new fungus on Cyperus iria. Amer. Jour. Bot. 48(10): 859–862. Illus. 1961—Duosporium cyperi gen. et sp. nov., collected on Cyperus iria Linn., is characterized by the production of 2 types of conidia, macroconidia and microconidia. The macroconidia are straight, cylindrical, triseptate, with their middle cells dark brown, long, thick-walled, and end cells much paler or subhyaline, short, thin-walled, the middle and the end cells being equally wide. The microconidia are nonseptate, spherical, dark brown, prominently verrucose, and produced apically on the conidiophores like the macroconidia; occasionally also formed as secondary conidia on germinating 3-septate macroconidia in culture. The formation of 2 distinct types of conidia in Duosporium and the features of its macroconidia characteristically differentiate it from its close relative Helminthosporium, although Duosporium. cyperi is not unique among fungi in producing 2 types of conidia.     

Life-history ofNeurospora intermedia in a sugar cane field

The life-history ofNeurospora in nature has remained largely unknown. The present study attempts to remedy this. The following conclusions are based on observation ofNeurospora on fire-scorched sugar cane in agricultural fields, and reconstruction experiments using a colour mutant to inoculate sugar cane burned in the laboratory. The fungus persists in soil as heat- resistant dormant ascospores. These are activated by a chemical(s) released into soil from the burnt substrate. The chief diffusible activator of ascospores is furfural and the germinating ascospores infect the scorched substrate. An invasive mycelium grows progressively upwards inside the juicy sugar cane and produces copious macroconidia externally through fire- induced openings formed in the plant tissue, or by the mechanical rupturing of the plant epidermal tissue by the mass of mycelium. The loose conidia are dispersed by wind and/or foraged by microfauna. It is suggested that the constant production of macroconidia, and their ready dispersal, serve a physiological role: to drain the substrate of minerals and soluble sugars, thereby creating nutritional conditions which stimulate sexual reproduction by the fungus. Sexual reproduction in the sugar- depleted cellulosic substrate occurs after macroconidiation has ceased totally and is favoured by the humid conditions prevailing during the monsoon rains. Profuse micro-conidiophores and protoperithecia are produced simultaneously in the pockets below the loosened epidermal tissue. Presumably protoperithecia are fertilized by microconidia which are possibly transmitted by nematodes active in the dead plant tissue. Mature perithecia release ascospores in situ which are passively liberated in the soil by the disintegration of the plant material and are, apparently, distributed by rain or irrigation water.     

Environmental factors and growth of Histoplasma capsulatum in soil

Summary Environmental factors influencing the growth ofHistoplasma capsulatum in soil have been studied. The role of temperature and moisture in the growth of the fungus was found to be critical. The fungus can tolerate very low temperatures, if the soil moisture content is high, but cannot withstand temperatures of 40° C or above for an extended period.Dry, sterile chicken manure and an extract of unsterile chicken manure showed an inhibitory effect on the growth of the fungus. However, the relationship between bird manure andH. capsulatum has not been satisfactorily clarified.Morphological studies ofH. capsulatum in soil showed that the fungus grows within the upper two inches of the soil and a majority of sporulation occurs within the upper one-half inch of soil. Morphological studies of the fungus, in the presence of chicken manure and chicken manure extract, showed an increased number of macroconidia and microconidia and decreased mycelial production.The growth ofH. capsulatum in soil is markedly affected by soil pH above 10 and below 5. No growth was observed on soil cultures outside these values. There was no definite pH range within these values in which the fungus grew more abundantly.     

Characteristics ofStreptomyces globisporus strain 0234A forming endospores in submerged cultures

Thermosensitive submerged endospores formed byStreptomyces globisporus 0234 and its natural variant A resembled those of thermoresistant actinomycetes not only in their morphology and ultrastructure, but also in the content of dipicolinic acid. The production of endospores containing this substance is unusual inStreptomyces while other features of the strain indicate relatedness to other streptomycetes. Chemotaxonomic analysis of variant A revealed the cell wall to be of chemotype I and fatty acid content typical ofStreptomyces. Most characteristics of surface cultures of variant A coincided with those of the original strain 0234 and its endosporeless variant B. Both the strain 0234 and its variants A and B produced identical antibiotics and pesticidal compounds.