Trichophyton mentagrophytes infection in a raccoon

Visible ringworm infection did not appear on a male raccoon captured in Bexar County, Texas. Shaving the abdomen of the animal caused the appearance of typical ringworm infection within a few months.Trichophyton mentagrophytes was isolated from the infected area. This is the first report on theTrichophyton infection in this animal.     

Repeated Ubiquitin Genes in Trichophyton mentagrophytes

Using Trichophyton mentagrophytes cDNA as a template, we performed PCR amplification with the UB1S and UB1R primers for isolation of a partial fragment of T. mentagrophytes ubiquitin gene. We screened the T. mentagrophytes cDNA library prepared with Uni-ZAP phage vector by hybridization with the T. mentagrophytes ubiquitin fragment, UB1S-UB1R. The nucleotide and deduced amino acid sequences of T. mentagrophytes ubiquitin gene encoded two ubiquitin repeats in 162 bp to 624 bp. The deduced amino acid sequences of ubiquitin from T. mentagrophytes shared about 98% similarity with those of Saccharomyces cerevisiae, Neurospora crassa, and Cryptococcus neoformans. Received: 28 April 1999 / Accepted: 22 June 1999     

Trichophyton mentagrophytes infection in laboratory white mice

Trichophyton mentagrophytes infection was studied in a breeding colony of 42 white mice. Symptoms were observed in only 3 out of the 12 animals shown to carry dermatophyte on their coats.Literature on Trichophyton mentagrophytes infection in mice is reviewed. The use of the technique developed by Mariat & Tapia (16) to isolate dermatophytes on cultures, specially for epidemiological surveys, is postulated.Attention is called to the importance of healthy animals, directly or indirectly, as carriers of fungi and sources of infection to other animals and human beings.

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Resumo E feita uma revisão da literatura sobre infecção, em camundongos, por T. mentagrophytes e descrita uma epizootia em camundongos do biotério da Escola Paulista de Medicina.Dos 42 animais usados para experimentação, 3 apresentavam lesões descamativas na cabeça e dorso. T. mentagrophytes foi isolado, em cultivo, de 2 dos camundongos com lesão e de 10 animais, clinicamente sadios. A tecnica desenvolvida por Mariat & Tapia para isolamento de fungos do tegumento de animais e de pacientes, com ou sem lesões visiveis, em áreas extensas do corpo, parece ser a mais indicada, pela praticabilidade e facilidade de seu uso, principalmente em amplos inquéritos epidemiológicos. Chama-se atenção para a importância dos animais sadios, como vetores de esporos de fungos e fontes de infecção, diretamente ou indirectamente, para o homem e outros animais.

     

Dermatophytosis of pigs by Trichophyton mentagrophytes

We describe the isolation of Trichophyton mentagrophytes in two family-operated farms where the animals were suffering skin ailments characterized by a swelling and a reddening of the back and flanks.This condition affected 2 and 5% respectively of the animals on the farms, the younger ones being more frequently affected.     

Arbuscular mycorrhiza colonization and development at suboptimal root zone temperature

Temperature has a strong influence on the activity of living organisms. This study, involving two indoor experiments, evaluated the effects of root zone temperature (10, 15 and 23°C) on the formation and development of arbuscular mycorrhizae (AM). In the first trial, greenhouse-grown sorghum [Sorghum bicolor (L.) Moench] was either colonized by Glomus intraradices Schenck & Smith or left non-mycorrhizal. Root length, root and shoot weight and root colonization were measured after 5, 10 and 15 weeks of plant growth. Although suboptimal root zone temperatures reduced growth in both mycorrhizal and non-mycorrhizal plants, mycorrhizal plants were larger than non-mycorrhizal plants after 15 weeks at 15 and 23°C. At suboptimal root zone temperatures, mycorrhizal inoculation sometimes slightly reduced root development. AM colonization was more affected than root growth at suboptimal root zone temperatures. Colonization was markedly reduced at 15°C compared with 23°C, and almost completely inhibited at 10°C. The second experiment was conducted in vitro using transformed carrot (Daucus carota L.) roots supporting G. intraradices. Mycelium length and spore number were measured weekly for 15 weeks. Spore metabolic activity (iodonitrotetrazolium reduction), root length and percentage root colonization were measured after 15 weeks. G. intraradices sporulation was reduced at temperatures below 23°C, while spore metabolic activity was significantly reduced only at 10°C. Root length and in particular percentage colonization were decreased at suboptimal temperatures. A negative interaction between AM hyphal growth and root growth resulting in reduced probability of contact at suboptimal root zone temperatures is proposed to explain the greater reduction observed in root colonization than in root and hyphal growth.     

Coumarin-induced disturbances of morphological development and cell wall formation in Trichophyton mentagrophytes.

When Trichophyton mentagrophytes thalli are placed on a medium containing 300 microgram/ml of coumarin, their growth rate is drastically reduced and the newly formed mycelium consists of curled and branched hyphae showing subapical bulges and swollen tips. Under the electron microscope, the most relevant abnormalities concern the cell walls which are often thickened by aberrantly shaped zones that are usually smeared unevenly over the surface of the "primary" wall instead of being deposited in discrete ridges. An ultracytochemical analysis suggests that the irregular thickenings are formed of chitin. Arguments suitable to explain the phenomena observed are discussed.     

Aberrant development of Trichophyton mentagrophytes hyphae cultured in the presence of Congo red

When Trichophyton mentagrophytes colonies were placed on a medium containing 150 micrograms/ml of Congo red, a dye which prevents chitin fibrillogenesis, their growth rate was reduced. The newly formed mycelium, examined under an ultraviolet microscope, consisted of thick, curled and branched hyphae endowed with swollen tips and subapical bulges. Short-time exposure revealed that the major sites of dye accumulation were the extension zones. Normally structured hyphae arose from aberrant mycelia when they were transferred onto a dye-free medium. The phenomena observed suggest that Congo red alters the wall properties of the extension zone, by inhibiting the gradual conversion of chitin chains, synthesized at the extreme tip, into microfibrils of increasing size and density.     

Submicroscopic morphology of trichophyton mentagrophytes grown at different temperatures

Several modifications were observed in Trichophyton mentagrophytes cultivated at 19° and 37 °C, i.e. nine degrees below and above the optimum of 28 °C. The phenomena included inhibition of the growth rate, changes in the gross aspects of the cultures as well as of the microscopic and submicroscopic morphology of the hyphal cells. At the ultrastructural level, in particular, it was shown that, at the suboptimal temperature, although the organelle structure in both young and aged hyphal cells remained nearly unchanged, unusual bodies of probable storage significance and plasmalemmasomes were formed.At the supraoptimal temperature, the youngest cells showed a normal organization but were richer in glycogen clusters and enveloped by a cell wall thicker than the ones at the optimal condition. In the cells far from the apex, the endomembrane integrity was lost and consequently an autolytic activity occurred. Degradation phenomena were detectable also at cell wall level. The cytological changes observed were tentatively correlated with a possible different sensitivity of the membrane system at the experimented temperature conditions.Investigation supported by a grant from Consiglio Nazionale delle Ricerche of Italy (Contract No. 7500536).     

Amino acid- or protein-dependent growth of Trichophyton mentagrophytes and Trichophyton rubrum

Culture conditions were examined for Trichophyton mentagrophytes and Trichophyton rubrum, which are major pathogens involved in dermatophytosis. They grew well in Sabouraud's dextrose broth or RPMI 1640. Growth in phosphate-buffered yeast nitrogen base supplemented with glucose was very slow, although growth improved significantly with the addition of amino acids or proteins to the medium. The fungi could also grow using human nail fragments as the only source of nutrition. Examination of proteases by substrate gel electrophoresis indicated that distinct sets of proteases are secreted from the dermatophytes in two different media, Sabouraud's dextrose broth and nail fragments. A protease inhibitor, phenylmethanesulfonyl fluoride, inhibited the growth of the fungi on nail fragments, but it did not inhibit their growth in Sabouraud's dextrose broth.     

Mating Genes of the Trichophyton mentagrophytes Complex

The mating type (-)-specific gene of the alpha-box and the mating type (+)-specific gene of the high-mobility group (HMG) DNA-binding domain were confirmed in zoophilic dematophytes of Arthroderma simii and A. vanbreuseghemii. The sequence of the alpha-box gene was 1,375 bp, containing 2 exons (from 172 to 463 bp and from 513 to 1,375 bp) in the A. simii (-) mating type strain and 1,380 bp, containing 2 exons (from 177 to 468 bp and from 518 to 1,380 bp) in the A. vanbreuseghemii (-) mating type strain. The sequence of the HMG gene was 1,871 bp, containing 2 exons (from 181 to 362 bp and from 426 to 1,440 bp, coding a protein of 398 amino acids) in the A. simii (+) mating type strain and 1,811 bp containing 2 exons (from 158 to 339 bp and from 403 to 1,381 bp, coding a protein of 386 amino acids) in the A. vanbreuseghemii (+) mating type strain. Of 15 animal isolates and 72 human isolates examined, the alpha-box gene was detected in five of the animal isolates and in none of the human isolates, while the HMG gene was detected in the other 10 of the animal isolates and in all of the human isolates. Phylogenetic analysis of the alpha-box and HMG genes of Trichophyton mentagrophytes complex strains and the Microsporum gypseum strain revealed that these strains were divided into 4 clusters; the first cluster consisting of A. vanbreuseghemii and the isolates from animals and humans, the second cluster consisting of A. simii, the third cluster consisting of A. benhamiae and the fourth cluster consisting of M. gypseum. These results indicate that anthropophilic T. mentagrophytes evolved from the A. vanbreuseghemii (+) mating strain.