User:Libby O'Brien/Blastoconidium
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[edit]Description
[edit]A blastoconidium (plural blastoconidia) is an asexual holoblastic conidia formed through the blowing out or budding process, which is a type of asexual reproduction that results in a bud arising from a parent cell.[1][2] The production of a blastoconidium can occur along a true hyphae, pseudohyphae, or a singular yeast cell.[3]The word conidia comes from the Greek word konis and eidos. Konis meaning dust and eidos meaning like.[4] The term bud comes from the Greek word blastos which means bud.[4] Yeasts such as Candida albicans, and Cryptococcus neoformans produce these budded cells known as blastoconidia.[5] [6]
Formation of a Blastoconidium
[edit]The mitotic budding process through which blastoconidia are formed consists on three step. The first step is bud emergence, and this is where the outer cell wall of the parental yeast thins. At the same time, there is growth of new cell wall and plasma membrane components. The next step is bud growth, and this process is regulated by the synthesis new cellular components and turgor pressure created by the parental yeast cell. While this bud is growing, mitosis of the parental nucleus is taking place. Once there are two identical nuclei, one will migrate to the forming blastoconidium. The last step is conidium separation, where a ring of chitin forms between the blastoconidium and the parental yeast cell, and this ring of chitin will eventually form the septum. Now that these two cells are separated, there will be a bud scar on the parental yeast cell. You can detect these bud scars due to the presence of more chitin in these areas, and this is also a way to detect how many times a yeast cell has undergone the budding process. Sometimes, the process of forming a blastoconidium does not end in the complete separation from the parental yeast cell. When this occurs, pseudohypha is formed, a filamentous chain of connected blastoconidia.[7]
Blastoconidium Virulence
[edit]
Fungal species that form blastoconidia are ubiquitous and commensal in nature, but can become opportunistic pathogens when the blastoconidia convert into the hyphal form through morphogenesis. The blastoconidia form is a part of the normal flora, while the hyphal form can be considered pathogenic and cause infection. [8]
For example, Candida albicans exist in different forms depending on certain environmental conditions, and the polymorphic nature of Candida albicans is a major virulence factor. The conditions at which this organism exists as a yeast (commensal) is when the temperature is less than 30° C, pH is less than 7, serum is absent, and nitrogen is abundant. The conditions at which this organism occurs as hyphae (pathogenic) is when the temperature is 37°C, pH is greater than 7, serum is present, and nitrogen is limiting. The blastoconidia form is less virulent to humans because the conditions required for grow at do not occur in humans, but the hyphal form is virulent because it thrives in the environment a human provides as a host. So, when Candida albicans converts to the hyphal form is when it will cause most infections.[8][9]
The blastoconidia form is also less virulent than the hyphal form based on the immune response they dictate in a host. Through a study conducted on Candida albicans, it was concluded that the blastoconidia form produced a different cytokine profile that resulted in more of a host immune response. The immune response that was activated will eliminate the blastoconidia form more efficiently, and proved that humans have more of a protective effect against an infection caused by Candida albican blastoconidia.[8] [10]
Unfortunately, the blastoconidia form of Candida albicans enhances attachment to a host which increases the virulence of the blastoconidia form. This is because blastoconidia produce adhesin proteins that facilitate and enable the yeast to attach to host cells. [10]
References
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- ^ "Glossary of Mycological Terms". Mycology | University of Adelaide. Retrieved 2021-11-11.
- ^ "blastoconidium", The Free Dictionary, retrieved 2021-11-18
- ^ Fenn, Joanne (March 2007). "Update of Medically Important Yeasts and a Practical Approach to Their Identification" (PDF). Lab Medicine. 38.
- ^ a b Davies, R.R. (1987–2001). "Blastospores". Medical Mycology. 25 (3): 187–190. doi:10.1080/02681218780000251. ISSN 1369-3786.
{{cite journal}}: CS1 maint: date format (link) - ^ Zaragoza, Oscar (2011). "Multiple Disguises for the Same Party: The Concepts of Morphogenesis and Phenotypic Variations in Cryptococcus neoformans†". Frontiers in Microbiology. 2: 181. doi:10.3389/fmicb.2011.00181. ISSN 1664-302X.
{{cite journal}}: CS1 maint: unflagged free DOI (link) - ^ Bottone, E. J.; Horga, M.; Abrams, J. (1999–2005). ""Giant" blastoconidia of Candida albicans: morphologic presentation and concepts regarding their production". Diagnostic Microbiology and Infectious Disease. 34 (1): 27–32. doi:10.1016/s0732-8893(99)00013-9. ISSN 0732-8893. PMID 10342104.
{{cite journal}}: CS1 maint: date format (link) - ^ Aggarwal, Anjali (2010-01-01). Medical Microbiology. Mittal Publications. ISBN 978-81-8293-034-6.
- ^ a b c Alburquenque, Claudio; Amaro, José; Fuentes, Marisol; Falconer, Mary A.; Moreno, Claudia; Covarrubias, Cristian; Pinto, Cristian; Rodas, Paula I.; Bucarey, Sergio A.; Hermosilla, Germán; Magne, Fabien (2019-06-01). "Protective effect of inactivated blastoconidia in keratinocytes and human reconstituted epithelium against C. albicans infection". Medical Mycology. 57 (4): 457–467. doi:10.1093/mmy/myy068. ISSN 1460-2709. PMID 30169683.
- ^ Reiss, Errol; Shadomy, H. Jean; Lyon, G. Marshall (2011-10-07). Fundamental Medical Mycology. Wiley. ISBN 978-0-470-17791-4.
- ^ a b Ciurea, Cristina Nicoleta; Kosovski, Irina-Bianca; Mare, Anca Delia; Toma, Felicia; Pintea-Simon, Ionela Anca; Man, Adrian (2020-06-06). "Candida and Candidiasis—Opportunism Versus Pathogenicity: A Review of the Virulence Traits". Microorganisms. 8 (6): 857. doi:10.3390/microorganisms8060857. ISSN 2076-2607. PMC 7355540. PMID 32517179.
{{cite journal}}: CS1 maint: PMC format (link) CS1 maint: unflagged free DOI (link)