Promitosis and Rod Occurrence in the Limax Ameba Vahlkampfia lobospinosa*

Abstract

Nuclear division and trophozoite structure and function were investigated in Vahlkampfia lobospinosa. During karyokinesis the nucleolus remained present and divided to form polar masses. Chromatids separated and were directed to the polar masses by spindle fibers within an intact nuclear membrane. No interzonal body was formed. Trophozoites consistently contained and extruded a rod-like structure 10-15 X 1-2 micron. Although it was found in other areas of the cell within the cytoplasm, this rod most frequently protruded from the uroid.

Tetramitus thermacidophilus n. sp., an Amoeboflagellate from Acidic Hot Springs

“…Flagellates of T. thermacidophilus are more similar to those of T. thorntoni although those are described to be oval rather than spindle shaped (Singh 1952). The closest relatives of T. thermacidophilus based on SSU rRNA sequences, T. lobospinosus , and T. horticolus , have no known flagellate stage (Fitzer and Wilhelm 1978; Sawyer, Nerad, and Munson 1992). Like T. thermacidophilus , both species move in the typical limax form of vahlkampfiids but eventually change to a more irregular multi‐lobed form (Fitzer and Wilhelm 1978; Sawyer, Nerad, and Munson 1992).…”

“…The closest relatives of T. thermacidophilus based on SSU rRNA sequences, T. lobospinosus , and T. horticolus , have no known flagellate stage (Fitzer and Wilhelm 1978; Sawyer, Nerad, and Munson 1992). Like T. thermacidophilus , both species move in the typical limax form of vahlkampfiids but eventually change to a more irregular multi‐lobed form (Fitzer and Wilhelm 1978; Sawyer, Nerad, and Munson 1992). The cysts of both species differ remarkably from the putative cysts of T. thermacidophilus : those of T. lobospinosus have two distinct layers one being the “thick and scalloped” ectocyst (Page 1988) while T. horticolus produces cysts with an unusual “hood‐like structure” that distinguishes the genus Singhamoeba from other vahlkampfiid amoebae and justified the erection of the genus (Sawyer et al 1992).…”

“…However, as for Learamoeba , the genus defining character for Singhamoeba is not reflected in phylogenetic distance (De Jonckheere and Brown 2005). Tetramitus horticolus and T. lobospinosus are at least slightly thermotolerant but are not reported from acidic environments (Fitzer and Wilhelm 1978; Sawyer et al 1992). Although probably pre‐adapted to thermal environments, the strict acidophilic life style was adopted more recently from a common ancestor of T. thermacidophilus and the related amoebae represented by environmental clones.…”

“…As an exception, T. vestfoldii was derived from a saline antarctic lake and grown at 5 °C (Murtagh et al 2002). Species like T. lobospinosus, T. entericus , and Tetramitus waccamawensis were isolated from feces or fecally contaminated soil and thrive at 37 °C (Fitzer and Wilhelm 1978; Page 1988; Sawyer et al 1998; Wilhelm and Anderson 1971).…”