title: Systematics and species-specific response to pH of Oxytricha acidotolerans sp. nov. and Urosomoida sp. (Ciliophora, Hypotricha) from acid mining lakes.
abstract: We investigated the morphology, phylogeny of the 18S rDNA, and pH response of Oxytricha acidotolerans sp. nov. and Urosomoida sp. (Ciliophora, Hypotricha) isolated from two chemically similar acid mining lakes (pH~2.6) located at Langau, Austria, and in Lusatia, Germany. Oxytricha acidotolerans sp. nov. from Langau has 18 frontal-ventral-transverse cirri but a very indistinct kinety 3 fragmentation so that the assignment to Oxytricha is uncertain. The somewhat smaller species from Lusatia has a highly variable cirral pattern and the dorsal kineties arranged in the Urosomoida pattern and is, therefore, preliminary designated as Urosomoida sp. The pH response was measured as ciliate growth rates in laboratory experiments at pH ranging from 2.5 to 7.0. Our hypothesis was that the shape of the pH reaction norm would not differ between these closely related (3% difference in their SSU rDNA) species. Results revealed a broad pH niche for O. acidotolerans, with growth rates peaking at moderately acidic conditions (pH 5.2). Cyst formation was positively and linearly related to pH. Urosomoida sp. was more sensitive to pH and did not survive at circumneutral pH. Accordingly, we reject our hypothesis that similar habitats would harbour ciliate species with virtually identical pH reaction norm.
authors.affiliation: Institute for Limnology of the Austrian Academy of Sciences, 5310 Mondsee, Austria. thomas.weisse@uibk.ac.at
authors.forename: Thomas
authors.initials: T
authors.lastname: Weisse
authors.forename: Michael
authors.initials: M
authors.lastname: Moser
authors.forename: Ulrike
authors.initials: U
authors.lastname: Scheffel
authors.forename: Peter
authors.initials: P
authors.lastname: Stadler
authors.forename: Thomas
authors.initials: T
authors.lastname: Berendonk
authors.forename: Guntram
authors.initials: G
authors.lastname: Weithoff
authors.forename: Helmut
authors.initials: H
authors.lastname: Berger
mesh_terms: D000143:Acids / Q000378:metabolism*; D001317:Austria; D016000:Cluster Analysis; D016054:DNA, Protozoan / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D004783:Environmental Microbiology; D020459:Genes, rRNA; D005858:Germany; D006863:Hydrogen-Ion Concentration; D008853:Microscopy; D008906:Mining; D008969:Molecular Sequence Data; D015388:Organelles / Q000648:ultrastructure; D016813:Oxytricha / Q000145:classification* / Q000166:cytology / Q000187:drug effects* / Q000302:isolation & purification; D010802:Phylogeny; D016053:RNA, Protozoan / Q000235:genetics; D012335:RNA, Ribosomal / Q000235:genetics; D017422:Sequence Analysis, DNA; D013312:Stress, Physiological
chemical_list: D000143:Acids; D016054:DNA, Protozoan; D004275:DNA, Ribosomal; D016053:RNA, Protozoan; D012335:RNA, Ribosomal; C065096:RNA, ribosomal, 26S