New Drug Can Address Amphibian Die-off Linked to Climate Change.

Contributor(s): 
February 17, 2014

Since the 1980s scientists have been alarmed about a massive global die-off of amphibians. In the intervening years chytid fungus infections, whose spread is linked to global warming, have been identified as the chief culprit.  A new study by Hoden, et al (2014) suggests that Nikkomycin Z may be useful in preventing their extinction.

Fungal infections are common among many plant and animal species, but alterations in the earth’s climate are driving changes in the distribution and virulence of fungal pathogens. , and there is ever-growing concern because of their potential to devastate natural ecosystems and influence human health. In recent years, Chytridiomycosis, a disease caused by the fungal pathogen Batrachochytrium dendrobatidis, has spread rapidly through a huge number of amphibian. Chytridiomycosis has been linked to dramatic population declines and often species extinctions of amphibian species in western North America, Central America, South America, eastern Australia, and the Dominica and Montserrat regions in the Carribean.  A recent study in PLoS One estimated that 1/3 of the world’s amphibian species are at risk, and that nationally species populations are declining at 3.7% every year. The implications for human health and the environment are a source of ever-growing concern.  

For many endangered amphibians, species survival can only be guaranteed through captive programs, with the eventual aim of reintroduction to the wild. Identifying effective antifungal treatments to cure Chytridiomycosis is not only essential for the survival of wild amphibian populations, but also for the successful reintroduction of species that only currently exist in captivity.   

Currently, the most widely accepted treatment for infected amphibian species is itraconazole, but it has toxic side effects that reduce its usefulness for many species. Safer antifungal treatments are needed for the successful control of this disease.

Holden et al., (2014) show that nikkomycin Z, a chitin synthase inhibitor, dramatically reduces the stability of B. dendrobatidis cell walls, completely inhibiting the growth and development of the fungus under laboratory conditions. In vitro, even low doses of nikkomycin Z were found to enhance the effectiveness of natural antimicrobial skin peptide. This work suggests that nikkomycin Z could serve as an effective treatment to limit the spread of B. dendrobatidis into uncolonised regions, and significantly reduce the fungal burden in frogs, salamanders and newts infected by this fungal disease.

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McCallum, M. L. (2007). “Amphibian Decline or Extinction? Current Declines Dwarf Background Extinction Rate”

Trends in Amphibian Occupancy in the United States.  http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0064347k

Nikkomycin Z is an effective inhibitor of the chytrid fungus linked to global amphibian declines. Whitney M. Holden, J. Scott Fites, Laura K. Reinert, Louise A. Rollins-Smith. Fungal Biology, Volume 118, Issue 1, January 2014, Pages 48–60