Metschnikowia bicuspidata

This student page has not been curated.

Introduction

Metschnikowia is a genus in the Kingdom Fungi (Naumov, 2011). Metschnikowia species are single-celled (i.e., yeast) parasites of the freshwater zooplankton genus Daphnia (ibid.).

Description and Significance

The organism exists as single-celled needle-shaped spores (Naumov, 2011). Metschnikowia lives in freshwater lakes ___where? It survives by ___ M. bicuspidata is a pathogen of Daphnia. If infection is successful, a M. bicuspidata spore uses the host's body to produce tens of thousands of identical spores. These increase in number until the Daphnia is killed and its carapace ruptures, introducing thousands of new spores into the water column.

Classification

Eukaryota, Fungi, Dikarya, Ascomycota, Saccharomycotina, Saccharomycetes, Saccharomycetales, Metschnikowiaceae, Metschnikowia (European Nucleotide Archive, accessed 21 April 2015)

Species

There are three varieties in the species: M. bicuspidata var. bicuspidata, var. californica, and var. chathamia (Naumov, 2011).

Genome Structure

Describe the size and content of the genome. How many chromosomes? Circular or linear? Other interesting features? What is known about its sequence?

Cell Structure, Metabolism and Life Cycle

Interesting features of cell structure; how it gains energy; what important molecules it produces.

M. bicuspidata gains energy by parasitising the freshwater zooplankton Daphnia. Daphnia encounter spores during feeding; the spores enter the Daphnia mouth along with algae and other small particles. Infection of Daphnia is successful if a spore can puncture the gut wall and begin reproducing, enclosed in the Daphnia body. Within the Daphnia body, M. bicuspidata uses energetic resources in the Daphnia body to reproduce (Hall et al., 2009). Susceptibility to infection varies across host genotypes ( ). Upon death due to infection, Daphnia may yield 10,000 to 70,000 spores per individual (Penczykowski et al., 2014).

Ecology and Pathogenesis

From left, an infected Daphnia, an uninfected Daphnia, and an infected Daphnia. On right, an electron microscopy image showing spores as they appear under the ruptured carapace of a Daphnia. (Hall et al.)

Habitat; symbiosis; biogeochemical significance; contributions to environment.
If relevant, how does this organism cause disease? Human, animal, plant hosts? Virulence factors, as well as patient symptoms.

M. bicuspidata kills the host D. magna in 7-25 days; a healthy D. magna typically lives 40-80 days (Ebert et al., 2000). Transmission is horizontal, meaning infection occurs within a host generation and is not transmitted from parent to offspring (Ebert et al., 2000). A single Daphnia carcass can dispense up to 70,000 spores into the water column (Penczykowski et al., 2014).

habitat symbionts biogeochemical significance contributions to environment how cause disease?

References

http://www.ebi.ac.uk/ena/data/view/Taxon:Metschnikowia%20bicuspidata%20var.%20bicuspidata%20NRRL%20YB-4993 European Nucleotide Archive. Metschnikowia bicuspidata var. bicuspidata NRRL YB-4993. accessed 21 April 2015.

Ebert, D., Lipsitch, M., Mangin, K. L. "The Effect of Parasites on Host Population Density and Extinction: Experimental Epidemiology with Daphnia and Six Microparasites." The American Naturalist. 2000. Volume 156(5). pp. 459-477.

Hall, S. R., Simonis, J. L., Nisbet, R. M., Tessier, A. J., Cáceres, C. E. "Resource Ecology of Virulence in a Planktonic Host‐Parasite System: An Explanation Using Dynamic Energy Budgets." The American Naturalist. 2009. Volume 174(2). pp. 149-162.

Naumov, G. I. "Molecular and genetic differentiation of small-spored species of the yeast genus Metschnikowia Kamienski." Microbiology. 2011. Volume 80(2). pp. 135-142.

Penczykowski, R. M., Lemanski, B. C. P., Sieg, R. D., Hall, S. R., Ochs, J. H., Kubanek, J., Duffy, M. A. "Poor resource quality lowers transmission potential by changing foraging behavior." Functional Ecology. 2014. Volume 28. pp. 1245-1255.

Author

Page authored by Katie Griebel and Jacob Gelarden, students of Prof. Jay Lennon at Indiana University.