Fungal Diversity & Evolution and Related Topics

Vocabulary flashcards covering key concepts related to fungal diversity, evolution, and associated pathology.

Human-pathogenic traits

Traits that have arisen in multiple fungal lineages due to convergent selection for thermotolerance, adhesion, immune evasion, and nutrient acquisition.

Estimated global range of fungal species

700,000 to 5,000,000 estimated species, with approximately 140,000 named/described.

Morphological diversity of fungi

Includes different forms such as yeast, hyphae, and mushrooms, which reflect ecological adaptation.

Sclerotium

Hardened mycelial mass that endures adverse conditions and germinates when conditions are favorable.

Fungal multicellularity

Contrasts with protist freeliving forms due to hyphal networks allowing resource translocation and coordinated reproduction through fruiting bodies.

Histoplasma capsulatum

Refers to its presence in the US Midwest, southern Ontario, and specific regions of South America/Africa.

Ergosterol

A sterol that modulates membrane fluidity in fungi, distinct from mammalian cholesterol.

Melanin in fungal cell walls

Component that protects fungi against UV radiation, oxidative stress, and host defenses.

Echinocandins

A class of antifungal that inhibits β1,3-D-glucan synthase, weakening the fungal cell wall.

A disease caused by Histoplasma capsulatum, presenting clinical signs like hypotension and respiratory distress.

What is Histoplasmosis

Dectin-1

An innate receptor on macrophages and dendritic cells that recognizes fungal β-glucan.

Opportunistic fungal pathogens

Pathogens that primarily infect immunocompromised hosts, unlike primary pathogens that can infect healthy individuals.

Neutropenic patients

Patients who are at high risk for invasive aspergillosis due to the lack of neutrophils needed to clear inhaled conidia.

Biofilms in fungal infections

Structured communities of fungi that resist drug treatment and immune clearance, leading to persistent infections.

The four major antifungal classes

Azoles (ergosterol synthesis), polyenes (ergosterol binding), echinocandins (β-glucan synthase inhibition), and 5-Fluorocytosine (DNA/RNA synthesis).

Mycotoxins

Toxic compounds produced by fungi, such as amatoxins from Amanita phalloides, which cause severe gastrointestinal upset.

5-Fluorocytosine mechanism

Converted to 5-Fluorouracil (5-FU) by fungal cytosine deaminase, blocking DNA/RNA synthesis.

Candida susceptibility to fluconazole

C. albicans is usually susceptible, while C. tropicalis, C. glabrata show less susceptibility, and C. auris is mostly resistant.

Complement system

A part of the immune system that aids in fungal clearance through opsonization and membrane attack complex formation.

Histoplasmosis case study

Clinical presentation in a 79-year-old male, with laboratorial findings indicating H. capsulatum positive in BAL culture.

Ergosterol as a target

Ideal antifungal target because it is unique to fungal membranes, absent in human cells.