A Yeast under Cover: the Capsule of<i>Cryptococcus neoformans</i>

Bose, Indrani; Reese, Amy J.; Ory, Jeramia; Janbon, Guilhem; Doering, Tamara L.

doi:10.1128/ec.2.4.655-663.2003

Cited by 217 publications

(204 citation statements)

References 115 publications

(66 reference statements)

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“…Esse padrão morfológico das leveduras de Cryptococcus spp. tem sido descrito como característico por diversos autores (Bose et al 2003, McFadden et al 2006, Okagaki et al 2010, Guarner & Brandt 2011, Kronstad et al 2011). Fig.1.…”

Section: Discussionunclassified

Características histomorfológicas e histoquímicas determinantes no diagnóstico da criptococose em animais de companhia

et al. 2014

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Pesq. Vet. Bras. 34(3):261-269, março 2014 261 RESUMO.-Sete casos de criptococose (seis gatos e um cão) foram estudados para estabelecer as características histomorfológicas e histoquímicas determinantes no diagnóstico histopatológico dessa condição. Os dados complementares relacionados à epidemiologia, aos aspectos clínicos, à localização das lesões e às alterações macroscópicas foram obtidos dos protocolos de necropsias e biópsias. Na histologia, as leveduras foram observadas no interior de macrófagos ou livres no parênquima, associadas à reação inflamatória linfo-histioplasmocítica que variou de escassa a acentuada. Pela técnica de hematoxilina-eosina (HE) as leveduras eram arredondadas, com célula central contendo um núcleo, circundada por um halo claro (cápsula geralmente não corada). As técnicas histoquímicas do ácido periódico de Schiff (PAS), Grocott e Fontana-Masson (FM) foram utilizadas e evidenciaram a parede das células das leveduras. Pelo FM observou-se a melanina presente nessas células. As téc- Seven cases of cryptococosis (six cats and one dog) were studied to establish the determining histomorphological and histochemical characteristics in the histopathological diagnosis of this condition. Additional data related to the epidemiology, clinical aspects, sites of the lesions, and gross findings were obtained from the necropsy and biopsy protocols. Histologically, yeasts were observed inside macrophages or free in the parenchyma, associated with scarse to severe lymphohistioplasmacytic inflammatory reaction. In the hematoxylin-eosin (HE) sections, the yeasts were round, with a central cell containing a nucleus, surrounded by a clear halo (usually non-stained capsule). The techniques of periodic Schiff acid (PAS), Groccot (GMS), and Fontana-Masson (FM) were utilized and demonstrated the wall of the yeast cells. The FM stain showed the melanin present in these cells. The Alcian blue and Mayer's mucicarmin stains showed mainly the yeast polysaccharide capsule. The diameter of the cells ranged from 1.67 to 10.00µm and the full diameter of the encapsulated yeasts varied between 4.17 e 34.16µm. Yeast buddings were better observed through the PAS stain and were narrow based, simple or multiple, mainly in the opposite poles of the cells or forming chains. The definitive diagnosis of cryptococosis was established through the histopathological exam, based on the specific morphology of the agent (encapsulated yeast) and on histochemical proprieties, mostly in the cases without fungal culture.

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Section: Discussionunclassified

Características histomorfológicas e histoquímicas determinantes no diagnóstico da criptococose em animais de companhia

et al. 2014

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“…In addition, the capsule prevents efficient phagocytosis by macrophages and thus leads to persistence of the pathogen in the host. Neurospora possesses proteins (Table 58) similar to those encoded by three genes (CAP10, CAP59, and CAP60) that are implicated in capsule formation in C. neoformans and are absent from S. cerevisiae (98). The finding that Neurospora lacks a fourth cap gene (CAP64), a glycosyltransferase required for O acetylation (CAS1) of the main capsule polysaccharide, and a UDP-glucuronate decarboxylase (CAS2), may explain the absence of this structure in Neurospora and also suggests noncapsule functions for CAP10/CAP59/CAP60 in filamentous fungi.…”

Section: Relationship To Animal and Plant Pathogensmentioning

confidence: 99%

Lessons from the Genome Sequence ofNeurospora crassa: Tracing the Path from Genomic Blueprint to Multicellular Organism

Borkovich

Alex

Yarden

et al. 2004

Microbiol Mol Biol Rev

597

618

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We present an analysis of over 1,100 of the ∼10,000 predicted proteins encoded by the genome sequence of the filamentous fungus Neurospora crassa. Seven major areas of Neurospora genomics and biology are covered. First, the basic features of the genome, including the automated assembly, gene calls, and global gene analyses are summarized. The second section covers components of the centromere and kinetochore complexes, chromatin assembly and modification, and transcription and translation initiation factors. The third area discusses genome defense mechanisms, including repeat induced point mutation, quelling and meiotic silencing, and DNA repair and recombination. In the fourth section, topics relevant to metabolism and transport include extracellular digestion; membrane transporters; aspects of carbon, sulfur, nitrogen, and lipid metabolism; the mitochondrion and energy metabolism; the proteasome; and protein glycosylation, secretion, and endocytosis. Environmental sensing is the focus of the fifth section with a treatment of two-component systems; GTP-binding proteins; mitogen-activated protein, p21-activated, and germinal center kinases; calcium signaling; protein phosphatases; photobiology; circadian rhythms; and heat shock and stress responses. The sixth area of analysis is growth and development; it encompasses cell wall synthesis, proteins important for hyphal polarity, cytoskeletal components, the cyclin/cyclin-dependent kinase machinery, macroconidiation, meiosis, and the sexual cycle. The seventh section covers topics relevant to animal and plant pathogenesis and human disease. The results demonstrate that a large proportion of Neurospora genes do not have homologues in the yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe. The group of unshared genes includes potential new targets for antifungals as well as loci implicated in human and plant physiology and disease

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“…7 Stimulated by several factors such as serum, iron limitation, and physiological CO 2 levels, 8,9 the capsule is composed of approximately 88% glucuronoxylomannan and 10% galactoxylomannan, and interferes with macrophage phagocytosis or confers direct immunosuppressive activity. 10,11 Melanin, which is a brown pigment made of polyphenol complexes, protects cells from environmental UV radiation and oxidative stress in the form of scavenging reactive oxygen species generated by the host defense system during infection. Melanin also enables Cryptococcus to escape from the lung to the central nervous system.…”

Section: Introductionmentioning

confidence: 99%