Batrachochytrium dendrobatidis Amphibian Chytrid Fungus Daniel Gillespie Bio 594: Mycology Fall 2013

Overview B. dendrobatidis (Bd) Chytridiomycosis Going Forward Classification Physiology Origin & Global Dissemination Chytridiomycosis Effect Notable Amphibians Population Declines Going Forward

Phylum: Chytridiomycota Classification Phylum: Chytridiomycota Class: Chytridiomycetes Order: Rhizophydiales Family: Incertae sedis

Naming 1999, Longcore et al., Mycologia Name derived from blue poison dart frog, Dendrobates azureus Infected specimens from National Zoo in D.C.

Description Bd infects the skin of amphibians It grows into a monocentric or colonial thallus Immature sporangia develop in the deeper layers Bd growth in skin of blue poison dart frog

Description Sporangia push outward to eject zoospores into the environment Discharge tubes develop Zoospores spherical with flagellum In lab only swam about 2 cm before encysting Bd zoospore on agar surface

Description Growth in wide range of conditions Optimal growth 17 – 25 ºC Above 25º growth slows Sexual reproduction has not been successful in labs May result in thick-walled, resistant sporangia

Origin Weldon et al. 2004 , Emerging Infectious Diseases Studied museum specimens from around the world First positive: 1938, South Africa First positive outside Africa: 1961, Quebec Primary host: Xenopus laevis Xenopus laevis

Dissemination X. laevis spread began in 1930s worldwide Pregnancy assay Pet trade Since, other vectors have been suggested

Chytridiomycosis Infects skin of frogs 2 hypotheses on death of frogs: Outer layers – stratum corneum and stratum granulosum 2 hypotheses on death of frogs: Inhibition of skin function Excretion of proteolytic enzymes Growth results in hyperkeratosis Lesions often form in area of infection

Notable Amphibians Several species do not show clinical signs of infection X. laevis produces antimicrobial peptides in skin Peptides act as barrier Frogs also showed immune system responses fighting Bd growth

Frog Declines Since 1980 Many areas experiencing wavelike declines 435 frog species declining 233 attributed to habitat loss and exploitation Many areas experiencing wavelike declines Areas of significant impact include Australia and So. America

Map of Spread

Going Forward Why Care? Biodiversity Importance as Indicator Species Approximately 7,000 species New species discovered constantly Importance as Indicator Species Sensitive to environment Abundant in wetland habitats Oreophryne gagneorum, discovered in September 2013 in Papa New Guinea

Going Forward What can we do? Research Bd genome recently sequenced Frogs are hard to find Current research is limited Bd genome recently sequenced Focus on population effects and possible cure needed

References Berger, L., Hyatt, A. D., Speare, R., & Longcore, J. E. (2005). Life cycle stages of the amphibian chytrid Batrachochytrium dendrobatidis. Diseases of aquatic organisms, 68, 51-63. Berger, L., Speare, R., Hines, H. B., Marantelli, G., Hyatt, A. D., McDonald, K. R., ... & Tyler, M. J. (2004). Effect of season and temperature on mortality in amphibians due to chytridiomycosis. Australian Veterinary Journal, 82(7), 434-439. Berger L, Speare R, Hyatt A (1999) Chytrid fungi and amphibian declines: overview, implications and future directions. In: Campbell A (ed) Declines and disappearances of Australian frogs. Environment Australia, Canberra, p 23–33 Johnson, M. L., & Speare, R. (2005). Possible modes of dissemination of the amphibian chytrid Batrachochytrium dendrobatidis in the environment. Diseases of aquatic organisms, 65, 181-186. Kilpatrick, A. M., Briggs, C. J., & Daszak, P. (2010). The ecology and impact of chytridiomycosis: an emerging disease of amphibians. Trends in Ecology & Evolution, 25(2), 109-118. Kriger, K. M., & Hero, J. M. (2007). The chytrid fungus Batrachochytrium dendrobatidis is non‐randomly distributed across amphibian breeding habitats.Diversity and Distributions, 13(6), 781-788. Longcore, J. E., Pessier, A. P., & Nichols, D. K. (1999). Batrachochytrium dendrobatidis gen. et sp. nov., a chytrid pathogenic to amphibians. Mycologia, 219-227. Morgan, J. A., Vredenburg, V. T., Rachowicz, L. J., Knapp, R. A., Stice, M. J., Tunstall, T., ... & Taylor, J. W. (2007). Population genetics of the frog-killing fungus Batrachochytrium dendrobatidis. Proceedings of the National Academy of Sciences, 104(34), 13845-13850. Orchard, S. A. (1999). The Gordian knots of the international declining amphibian populations task force (DAPTF). In: Campbell A (ed) Declines and disappearances of Australian frogs. Environment Australia, Canberra, p 9-13 Piotrowski, J. S., Annis, S. L., & Longcore, J. E. (2004). Physiology of Batrachochytrium dendrobatidis, a chytrid pathogen of amphibians. Mycologia,96(1), 9-15. Ramsey, J. P., Reinert, L. K., Harper, L. K., Woodhams, D. C., & Rollins-Smith, L. A. (2010). Immune defenses against Batrachochytrium dendrobatidis, a fungus linked to global amphibian declines, in the South African clawed frog, Xenopus laevis. Infection and immunity, 78(9), 3981-3992. Rosenblum, E. B., James, T. Y., Zamudio, K. R., Poorten, T. J., Ilut, D., Rodriguez, D., ... & Stajich, J. E. (2013). Complex history of the amphibian-killing chytrid fungus revealed with genome resequencing data. Proceedings of the National Academy of Sciences, 110(23), 9385-9390. Skerratt, L. F., Berger, L., Speare, R., Cashins, S., McDonald, K. R., Phillott, A. D., ... & Kenyon, N. (2007). Spread of chytridiomycosis has caused the rapid global decline and extinction of frogs. EcoHealth, 4(2), 125-134. Stuart, S. N., Chanson, J. S., Cox, N. A., Young, B. E., Rodrigues, A. S., Fischman, D. L., & Waller, R. W. (2004). Status and trends of amphibian declines and extinctions worldwide. Science, 306(5702), 1783-1786. Weldon, C., du Preez, L. H., Hyatt, A. D., Muller, R., & Speare, R. (2004). Origin of the amphibian chytrid fungus. Emerging infectious diseases, 10(12), 2100. Welsh Jr, H. H., & Ollivier, L. M. (1998). Stream amphibians as indicators of ecosystem stress: a case study from California's redwoods. Ecological Applications, 8(4), 1118-1132.

Links to Photos http://www.amphibianark.org/the-crisis/chytrid-fungus/ http://www.arkive.org/dyeing-poison-frog/dendrobates-tinctorius/image-G15404.html http://www.arkive.org/dyeing-poison-frog/dendrobates-tinctorius/image-G104487.html Longcore, J. E., Pessier, A. P., & Nichols, D. K. (1999). Batrachochytrium dendrobatidis gen. et sp. nov., a chytrid pathogenic to amphibians. Mycologia, 219-227 http://upload.wikimedia.org/wikipedia/commons/b/b4/Xenopus_laevis_02.jpg http://www.fcps.edu/islandcreekes/ecology/Amphibians/Bullfrog/bull2.jpg http://www.xenopus.com/box_of_frogs.jpg http://mongabay-images.s3.amazonaws.com/13/0918fungus1.jpg http://www.earthfiles.com/Images/news/A/AmphibianAfricanClawedFrogLo.jpg http://cdn4.sci-news.com/images/2013/09/image_1400_3-Oreophryne.jpg