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Bayli Russ ALVEOLATES April 9, 2015

WHAT IS IT?

¡ Alveolates- Major superphylum of protists ¡ Group of single-celled eukaryotes that get their nutrition by predation, photoautotrophy, and intracellular parasitism ¡ Spherical basophilic organisms (6-9 µm diameter) ¡ Most notable shared characteristic is presence of cortical alveoli, flattened vesicles packed into linear layer supporting the membrane, typically forming a flexible pellicle

(Leander, 2008)

WHAT IS IT?

¡ 3 main subgroups: § Ciliatesà predators that inhabit intestinal tracts and flesh § Dinoflagellatesà mostly free living predators or photoautotrophs, release toxins § Apicomplexansà obligate parasite; invade host cells ¡ Several other lineages such as: § Colpodella § Chromera § Colponema § Ellobiopsids § Oxyrrhis § Rastrimonas § Parvilucifera § Perkinsus

(Leander, 2008)

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HOW DOES IT KILL AMPHIBIANS?

¡ Cause infection and disease in amphibian populations § Infection = parasite occurs in host; occupying intestinal lumen § Disease = advanced infection; presence of spores in tissues; occupying intestinal mucosa, liver, skin, rectum, mesentery, adipose tissue, pancreas, spleen, kidney, and somatic musculature ¡ Effects on organs § Filters into host’s internal organs in mass amounts § Causes organ enlargement and severe tissue alteration § Obliterates kidney and liver structure § System shut-down = DEATH ¡ How its introduced to environment § Birds § Insects ¡ How it spreads/transmission: § Ingestion of spores § Feces of infected individuals § Tissues from dead/dying infected tadpoles § Free-floating spores

(Cook, 2008)

HOW DOES IT KILL AMPHIBIANS?

¡ Environmental influence § pH of water (5.5-7.5 = mass zoospore hatching) § Salt = mass zoospore hatching § Zoospores = disease condition = DEATH ¡ Variety of host species ¡ Age of amphibian § Kills off tadpoles § Sometimes persists through metamorphosis § Infection in adults ¡ Very high rates of mortality

(Cook, 2008)

EVIDENCE OF DIE-OFFS OR DECLINES?

¡ (Green, 2002): § Severe infection to be the cause of 2 mortality events and contributor to 2 other mortality events occurring only in Ranid tadpoles in MN, MI, NC, and NH § Occurred in no onset pattern & each of the 4 events occurred in 4 separate months § Observations suggesting that infection causes >95% mortality rate in this population of tadpoles § Parasite said to be undetermined, but resembles Dermocystidium ¡ (Jones et al. 2012): § Analysis of rRNA sequence reveal that the organism from Green’s experiment is actually most closely related to type of alveolate protozoa

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EVIDENCE OF DIE-OFFS OR DECLINES?

¡ (Landsberg et al., 2013): § Multispecies amphibian larval mortality event § American bullfrogs (L. catesbeianus) § Southern leopard frogs (L. sphenocephalus) § Gopher frogs (L. capito) § Occurred in Florida § Only major events due to alveolate parasite § Die-off in pond § Infection increased since survey § No older bullfrogs 2 months later

EVIDENCE OF DIE-OFFS OR DECLINES?

¡ (Davis et al., 2007): § Mortality event of southern leopard frog (R. sphenocephala) § Northeast Georgia § Surveyed 5 ponds § 25% of 87 specimens were infected § Complete, rapid die-off of R. Sphenocephala tadpoles in one pond while surveys were still going on § All organs infected § Mainly liver and kidneys § Swelling of organs

EVIDENCE OF DIE-OFFS OR DECLINES?

¡ (Cook, 2008): § Mass mortality of gopher frog (R. sevosa) tadpoles § Infection by Dermomycoides sp. § Primary breeding pond in Mississippi § Zoospore penetration § Death within weeks post-embryo § Lab infections § Infected species of Rana, Acris, Hyla, Pseudacris, and Gastrophryne § Disease condition in Hyla gratiosa, R. capito, R. catesbeiana, R. clamitans, R. sevosa, and R. sphenocephala § Documented places of infection and disease: § Florida, Georgia, Mississippi, Maine, New Hampshire, Virginia, North Carolina and Minnesota § Documented species infected and deceased from infection: § R. servosa, R. sylvatica, R. sphenocephala, R. septrionalis, R. clamitans, R. catesbeiana and P. crucifer

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WHY IS IT THE MOST IMPORTANT?

¡ New and emerging parasite ¡ All species are potential hosts, not just specific species as seen in Ranavirus ¡ No limit on occurrence to a certain time period or place § Reported in variety of geological areas & in different seasons § No pattern of environmental requirements ¡ Overwhelms populations with little to no recovery after infection occurs § No way to combat it ¡ Completely destroys the organs causing failure ¡ Alveolate infections are moving/spreading geographically § First reported event in New Hampshire and now has reached Alaska, Georgia, Florida, Maine, Mississippi, Minnesota, North Carolina, and Virginia ¡ Large realm of unknown § Halts prevention

REFERENCES

¡ Cook JO (2008) Transmission and occurrence of Dermomy- coides sp. in Rana sevosa and other ranids in the North Central Gulf of Mexico States. MS thesis, University of Southern Mississippi, Hattiesburg, MS. ¡ Davis, Andrew K. et al. (2007) Discovery of a Novel Alveolate Pathogen Affecting Southern Leopard Frogs in Georgia: Description of the Disease and Host Effects. EcoHealth, 4: 310-317. ¡ Green DE, Converse KA, Schrader AK (2002) Epizootiology of sixty-four amphibian mortality events in the USA, 1996−2001. Ann NY Acad Sci 969:323−339. ¡ Jones, E.B. et al. (2012) Granulomatous myositis associated with a novel alveolate pathogen in an adult southern leopard frog (Lithobates sphenocephalus). Dis Aquat Org, 102: 163-167. ¡ Landsberg, J.H. et al. (2013) Co-infection by alveolate parasites and frog virus 3-like ranavirus during an amphibian larval mortality event in Florida, USA. Dis Aquat Org, 4: 88-99. ¡ Leander, Brian S. 2008. Alveolates. Alveolata. Version 16 September 2008 (under construction). http://tolweb.org/Alveolates/ 2379/2008.09.16 in The Tree of Life Web Project, http://tolweb.org/

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