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Survival of a Choanoflagellate Following Acute Exposure to Abiotic Stressors
Author(s) -
Rodriguez Sara Scarlet,
Julian David
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.23.1_supplement.778.3
Subject(s) - salinity , abiotic component , abiotic stress , biology , ecology , botany , chemistry , biochemistry , gene
Choanoflagellates are the unicellular antecedents of animals. Among them, the Acanthoecidae are a diverse group found in aquatic habitats that can contain steep clines of temperature, salinity, oxygen, and hydrogen sulfide (H 2 S). It is unclear whether acanthoecids in general are tolerant of many stressors, or if they exhibit endemism, with individual species being adapted to some stressors.We tested stress tolerance of the acanthoecid Diaphoneca grandis after acute 24h changes in temperature, pH, salinity, O 2 , and H 2 S under normoxia and anoxia. Survival was assessed using morphology, propidium iodide labeling to indicate loss of plasma membrane integrity, and phosphatidylserine (PS) externalization. Compared to control conditions (0 H 2 S, 10 °C, 33 ppt salinity, pH 8.0, 21% O 2 ), viability was significantly decreased at 0.11‐3.3 mM H 2 S, =20 °C, =20 or =50 ppt salinity, pH =7.7 or =8.3 and 0.21‐2.1% O 2 but not anoxia. When H 2 S exposure was coupled with anoxia, cell viability was higher than under normoxia. PS externalization was significantly increased following exposure to high temperature, hypersalinity, alkaline pH, and H 2 S, which may indicate multiple cell death pathways. The tolerance range of D. grandis to each abiotic stressor was substantially less than that predicted by the maximum ranges of acanthoecids as a group, suggesting that the high stress tolerance of acanthoecids results from endemism.