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Examples Of Symbiosis

Examples Of Symbiosis

Microbes Can Alter Behavior

Toxoplasma is a parasitic protist that can infect a range of animals, including mice, rats, and people. But to reproduce sexually, it must infect a cat. In an amazing and complex relationship, the parasite enters the brain of infected rodents, where it changes the host's behavior, making it more likely to be caught and eaten by a cat!

Mice infected with toxoplasma lose their fear of cats. They are more active, and more likely to spend time exploring open spaces. In one study, male rats were actually attracted to the smell of cat urine.

Once inside the cat, the protist enters cells in the intestinal wall, reproduces sexually, and releases cysts that are carried out with the cat's feces. From there, the cysts are picked up and eaten by the next host.

Infected people behave differently too. Toxoplasma infection is correlated with mental conditions including schizophrenia, obsessive-compulsive disorder, and autism. The link between toxoplasma infection and schizophrenia is stronger than for any single gene identified to date.


Microbes May Help Drive Evolution

Different types of wolbachia bacteria infect a range of animals that include insects and roundworms. In some species, the bacteria cause sexual incompatibility. Infected parents can reproduce with each other, and so can uninfected parents. But an infected parent and uninfected parent can't reproduce together. Wolbachia infection may create the "reproductive isolation" necessary for one species to diverge into two.


Microbes Are Important For Human Health

Human breast milk contains oligosaccharides, short chains of sugar molecules that provide absolutely no nutritional benefit to babies. Why do mothers spend energy making these molecules? It's to feed microbes that are important for the baby's developing immune system.

Formula-fed babies—who presumably have fewer of these beneficial, oligosaccharide-eating, immune-boosting microbes—are more likely than breast-fed babies to suffer from allergies. Early studies suggest that when babies drink formula that is supplemented with oligosaccharides similar to those found in breast milk, they become less likely to suffer from skin allergies and eczema during the first two years of life.

To learn more about how microbes keep us healthy, visit Your Microbial Friends.

References

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Brucker, R.M. & Bordenstein, S.R. (2012). Speciation by symbiosis. Trends in Ecology & Evolution, 27(8), 443-451.

Currie, C.R., Scott, J.A., Summerbell, R.C. & Malloch, D. (1999). Fungus-growing ants use antibiotic-producing bacteria to control garden parasites. Nature, 398, 701-704. doi: 10.1038/19519

Gatkowska, J., Wieczorek, M., Dziadek, B., Dzitko, K. & Dlugonska, H. (2013). Sex-dependent neurotransmitter level changes in brains of Toxoplasma gondii infected mice. Experimental Parasitology, 133(1), 1-7. doi: 10.1016/j.exppara.2012.10.005

Kaushik, M., Lamberton, P.H.L. & Webster, J.P. (2012). The role of parasites and pathogens in influencing generalised anxiety and predation-related fear in the mammalian central nervous system. Hormones and Behavior, 62(3), 191-201. doi: 10.1016/j.yhbeh.2012.04.002

Kroiss, J., Kaltenpoth, M., Schneider, B., Schwinger, M.-G., Hertweck, C.,Maddula, R.K., Strohm, E. & Svatos, A. (2010). Symbiotic streptomycetes provide antibiotic combination prophylaxis for wasp offspring. Nature Chemical Biology, 6, 261-263. doi: 10.1038/nchembio.331

Land, D. (2012). Microbes for health and survival. Quarterly: For alumni, friends, faculty and students of the University of Wisconsin School of Medicine and Public health, 14(3), 10-13.

Markmann, K., Giczey, G., Parniske, M. (2008). Functional adaptation of a plant receptor-kinase paved the way for the evolution of intracellular root symbioses with bacteria. PLoS Biology 6(3), e68. doi:10.1371/journal.pbio.0060068

Maraquez, L.M., Redman, R.S., Rodriguez, R.J. & Roossinck, M.J. (2007). A virus in a fungus in a plant: Three-way symbiosis required for thermal tolerance. Science, 315(5811), 513-515. doi: 10.1126/science.1136237

Nyholm, S.V., Song, P., Dang, J., Bunce, C. & Giurguis, P. R. (2012). Expression and putative function of innate immunity genes under in situ conditions in the symbiotic hydrothermal vent tubeworm Ridgeia piscesae. PLoS ONE, 7(6), e38267. doi: 10.1371/journal.pone.0038267

Paracer, S. & Ahmadjian, V. (2000). Symbiosis: An introduction to biological associations (2nd ed.). New York, NY: Oxford University Press.

Rigaud, T. & Moreau, J. (2004). A cost of Wolbachia-induced sex reversal and female-biased sex ratios: decrease in female fertility after sperm depletion in a terrestrial isopod. Proceedings of the Royal Society B, 271, 1941-1946.

Seipke, R.F., Barke, J., Brearley, C., Hill, L., Yu, D.W., Gross, R.J.M., Hutchings, M.I. (2011). A single Streptomyces symbiont makes multiple antifungals to support the fungus farming ant Acromyrmex octospinosus. PLoS ONE, 6(8), e22028. doi: 10.1371/journal.pone.0022028

Wimpee, C.F., O'Grady, E.A. & Olson, E.L. (2009). Overview of defensive mutualism in the marine environment. In White, J.F., Jr., Torres, M.S., (Eds.), Defensive Mutualism in Microbial Symbiosis (pp. 21-34). Boca Raton, FL: CRC Press.

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APA format:
Genetic Science Learning Center (2014, June 22) Examples Of Symbiosis. Learn.Genetics. Retrieved August 30, 2014, from http://learn.genetics.utah.edu/content/microbiome/symbiosis/
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