Antarctic amoebae adventures

• Published in: The Journal of Eukaryotic Microbiology
• Main Authors: MORAN, DAWN M., ANDERSON, O. R., DENNETT, MARK R., CARON, DAVID A., GAST, REBECCA J.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2005
• Subjects: Antarctic; Ross Sea; The Antarctic; Antarc*; Antarctica
• Online Access: http://dx.doi.org/10.1111/j.1550-7408.2005.05202003_1_62.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1550-7408.2005.05202003_1_62.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1550-7408.2005.05202003_1_62.x

Ice, slush, sediment and water samples were collected from the Ross Sea, Antarctica and enriched with a variety of inorganic and organic nutrients. All cultures were maintained at an ambient temperature of 1°C, and amoebae were observed to occur in the slush, sediment and water enrichments. Amoebae were isolated into clonal or monocultures, and their characterization was accomplished using a combination of molecular and morphological methods. Full‐length 18S ribosomal DNA sequence data indicated that seven of the isolates represented four different amoebae of the Vexilliferidae and Vannellidae families. Acquisition of 18S ribosomal sequences from the parasomes of two amoebae further confirmed their identification as Neoparamoeba species. Light microscopy, fluorescence microscopy and TEM observations were accomplished and further support the molecular data. To determine whether these amoebae represented psychrophilic strains, their temperature tolerances were tested. Cultures were inoculated at 1°C and the temperature was raised 1°C/day (to a total of 5°), and then held at that temperature for 6 days. This pattern was repeated in 5°‐increments, up to 20°C. The cultures were observed frequently for death and possible cyst formation. Three (2 types of Vannellids) out of seven amoeba cultures survived up to 20°C. Whereas, the two different Vexilliferids died at a range of temperatures between 10°C and 20°C. These data indicate that amoebae found in the Antarctic are varied in their physiological adaptation for growth at cold temperatures.