Journalof Medicaland VeterinaryMycology(1992), 30, Supplement 1, 29-39
Advances in dermatophytes and dermatophytosis
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S. T A N A K A 1, R. C. SUMMERBELL 2, R. TSUBOI 3, T. K A A M A N 4, P. G. SOHNLE 5, T. MATSUMOTO 6 AND T. L. R A Y 7
XDepartment of Dermatology, Shiga University of Medical Science, Seta, Tsukinowacho, Otsu, Japan; 2Mycology Lab, Ontario Ministry of Health, Box 9000, Terminal A, Toronto, Ontario, Canada; 3Department of Dermatology, Juntendo University School of Medicine, 2-1-1 Hongo, Tokyo, Japan; 4Department of Dermatology, Karolinska Institutet, SOdersjukhuset, Stockholm, Sweden; 5Research Services~151, Veterans Administration Medical Center, Milwaukee, Wisconsin, USA; 6Department of Dermatology, Toshiba General Hospital, 6-3-22 Higashi-oi, Shinagawa-ku, Tokyo 140, Japan; and 7Department of Dermatology, University of Iowa College of Medicine, Iowa City, Iowa, USA During the last 40 years, studies of mycotic infections in humans and animals have increased significantly. Nearly every medical specialty now includes mycotic diseases in its scientific progam and publications, but 3 decades ago only dermatologists and mycologists shared an interest in mycotic diseases. Therefore, we dare say that medical mycology grew with its friend, dermatology. Superficial cutaneous mycotic infections primarily involve the keratinized tissues of the epidermis, pilosebaceous follicles and nails. Since their aetiological agents have a predilection for the skin and its appendages, hairs and skin scrapings are readily obtained for direct microscopic examination and culture studies. Dermatophytosis has been known for a long time and the dermatophytes were among the first pathogenic micro-organisms to be recognized and named [8]. 'Dermatophyte' literally means 'skin plant'. We do not know when or by whom the term was coined. However, in 'A Supplement to the Oxford English Dictionary', the earliest documented uses go back to 1882 and 1885. In his 1977 historical review of dermatophytes, Ajello [1] marked 11 milestones that contributed major scientific developments and breakthroughs in this field. He stated that development of our knowledge of the dermatophytes parallels that of medical mycology in general. His statement is still accurate and well justified in 1991 because recent advances in dermatophytes and dermatophytosis have been achieved principally by modern scientific techniques. The following information will provide interested scientists an opportunity to keep abreast of the current concepts pertaining to the dermatophytes and dermatophytosis.
Ultrastructural study of dermatophytes and their teleomorphs Ascosporogenesis in Arthroderma vanbreuseghemii, a teleomorph of Trichophyton mentagrophytes has been investigated ultrastructurally. Electron microscopy of the Correspondence address: Thomas L. Ray, Dept. of Dermatology, University of Iowa College of Medicine, Iowa City, Iowa 52242, USA. 29
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30
TANAKA ET AL .
FIG. 1. (a) Mature ascospore observed by freeze substitution. The nucleus (N) is marked, x36 000. (b) Mature ascospore observed by post-embedding wheat germ agglutinin-colloidal gold complex staining. Gold deposits are present in the inner layer of the ascospore cell wall. The nucleus (N) is marked, x30 000. (c) Young ascus observed by freeze substitution, with Golgi apparatus (G) at the periphery and glycogen granules (g) marked. Arrowhead indicates tubular membranous structure, x 63 000. (d) Young ascus observed by freeze substitution, showing tubular membranous structure (arrowhead) in direct contact with spore delimiting membrane (SDM). Glycogen granules (g) are marked, x63 000.
ascus revealed that post-meiotic nuclei were delimited by progressive invagination of the spore delimiting membrane (SDM) [16]. Ascospore maturation began with separation of the SDM, followed by deposition of cell wall material between the two envelopes of the SDM. The inner track developed into an ascospore plasma membrane and an inner leaf of the outer track developed into an ascospore investing membrane. At maturity, the epiplasma of the ascus underwent lysis to release the ascospores [15]. With minor differences, these processes are similar in all ascomycetous fungi (Fig. 1) [2]. A detailed cytokinesis study was performed using freeze substitution techniques and post-embedding carbohydrate cytochemistry with a wheat germ agglutinin-colloidal gold complex [17]
Ascospore cell wall formation. Ascospore development in ascomycetous fungi is a model for cell wall formation. Cell wall formation is divided into two phases. In primary wall formation, undifferentiated cell wall material is laid down between the SDM of the initial ascospore. All subsequent deposition is secondary wall formation and varies considerably in structure between species. Therefore, the mode of secondary wall development is a useful characteristic for determining fungal taxonomy [2]. In A. vanbreuseghemii, the mature ascospore cell wall consists of an inner electron-
Med Mycol Downloaded from informahealthcare.com by Chulalongkorn University on 01/04/15 For personal use only.
ADVANCES IN DERMATOPHYTES AND DERMATOPHYTOSIS
Advances in dermatophytes and dermatophytosis
Med Mycol Downloaded from informahealthcare.com by Chulalongkorn University on 01/04/15 For personal use only.
S. T A N A K A 1, R. C. SUMMERBELL 2, R. TSUBOI 3, T. K A A M A N 4, P. G. SOHNLE 5, T. MATSUMOTO 6 AND T. L. R A Y 7
XDepartment of Dermatology, Shiga University of Medical Science, Seta, Tsukinowacho, Otsu, Japan; 2Mycology Lab, Ontario Ministry of Health, Box 9000, Terminal A, Toronto, Ontario, Canada; 3Department of Dermatology, Juntendo University School of Medicine, 2-1-1 Hongo, Tokyo, Japan; 4Department of Dermatology, Karolinska Institutet, SOdersjukhuset, Stockholm, Sweden; 5Research Services~151, Veterans Administration Medical Center, Milwaukee, Wisconsin, USA; 6Department of Dermatology, Toshiba General Hospital, 6-3-22 Higashi-oi, Shinagawa-ku, Tokyo 140, Japan; and 7Department of Dermatology, University of Iowa College of Medicine, Iowa City, Iowa, USA During the last 40 years, studies of mycotic infections in humans and animals have increased significantly. Nearly every medical specialty now includes mycotic diseases in its scientific progam and publications, but 3 decades ago only dermatologists and mycologists shared an interest in mycotic diseases. Therefore, we dare say that medical mycology grew with its friend, dermatology. Superficial cutaneous mycotic infections primarily involve the keratinized tissues of the epidermis, pilosebaceous follicles and nails. Since their aetiological agents have a predilection for the skin and its appendages, hairs and skin scrapings are readily obtained for direct microscopic examination and culture studies. Dermatophytosis has been known for a long time and the dermatophytes were among the first pathogenic micro-organisms to be recognized and named [8]. 'Dermatophyte' literally means 'skin plant'. We do not know when or by whom the term was coined. However, in 'A Supplement to the Oxford English Dictionary', the earliest documented uses go back to 1882 and 1885. In his 1977 historical review of dermatophytes, Ajello [1] marked 11 milestones that contributed major scientific developments and breakthroughs in this field. He stated that development of our knowledge of the dermatophytes parallels that of medical mycology in general. His statement is still accurate and well justified in 1991 because recent advances in dermatophytes and dermatophytosis have been achieved principally by modern scientific techniques. The following information will provide interested scientists an opportunity to keep abreast of the current concepts pertaining to the dermatophytes and dermatophytosis.
Ultrastructural study of dermatophytes and their teleomorphs Ascosporogenesis in Arthroderma vanbreuseghemii, a teleomorph of Trichophyton mentagrophytes has been investigated ultrastructurally. Electron microscopy of the Correspondence address: Thomas L. Ray, Dept. of Dermatology, University of Iowa College of Medicine, Iowa City, Iowa 52242, USA. 29
Med Mycol Downloaded from informahealthcare.com by Chulalongkorn University on 01/04/15 For personal use only.
30
TANAKA ET AL .
FIG. 1. (a) Mature ascospore observed by freeze substitution. The nucleus (N) is marked, x36 000. (b) Mature ascospore observed by post-embedding wheat germ agglutinin-colloidal gold complex staining. Gold deposits are present in the inner layer of the ascospore cell wall. The nucleus (N) is marked, x30 000. (c) Young ascus observed by freeze substitution, with Golgi apparatus (G) at the periphery and glycogen granules (g) marked. Arrowhead indicates tubular membranous structure, x 63 000. (d) Young ascus observed by freeze substitution, showing tubular membranous structure (arrowhead) in direct contact with spore delimiting membrane (SDM). Glycogen granules (g) are marked, x63 000.
ascus revealed that post-meiotic nuclei were delimited by progressive invagination of the spore delimiting membrane (SDM) [16]. Ascospore maturation began with separation of the SDM, followed by deposition of cell wall material between the two envelopes of the SDM. The inner track developed into an ascospore plasma membrane and an inner leaf of the outer track developed into an ascospore investing membrane. At maturity, the epiplasma of the ascus underwent lysis to release the ascospores [15]. With minor differences, these processes are similar in all ascomycetous fungi (Fig. 1) [2]. A detailed cytokinesis study was performed using freeze substitution techniques and post-embedding carbohydrate cytochemistry with a wheat germ agglutinin-colloidal gold complex [17]
Ascospore cell wall formation. Ascospore development in ascomycetous fungi is a model for cell wall formation. Cell wall formation is divided into two phases. In primary wall formation, undifferentiated cell wall material is laid down between the SDM of the initial ascospore. All subsequent deposition is secondary wall formation and varies considerably in structure between species. Therefore, the mode of secondary wall development is a useful characteristic for determining fungal taxonomy [2]. In A. vanbreuseghemii, the mature ascospore cell wall consists of an inner electron-
Med Mycol Downloaded from informahealthcare.com by Chulalongkorn University on 01/04/15 For personal use only.
ADVANCES IN DERMATOPHYTES AND DERMATOPHYTOSIS
