SURVEY FOR KARLOTOXIN PRODUCTION IN 15 SPECIES OF GYMNODINIOID DINOFLAGELLATES (KARENIACEAE, DINOPHYTA)¹

Abstract

Toxin analysis of 15 species of Kareniaceae revealed the presence of karlotoxin, KmTx 2, in only a single species (Karlodinium veneficum) but with variable activity in strains from the Swan (KmSwanTx 2‐1, 2.1 pg · cell−1; and KmSwanTx 2‐2, 0.53 pg · cell−1), Huon (KmHuonTx 2, 0.86 pg · cell−1), and Derwent rivers (<0.001 pg · cell−1) in Australia. A newly isolated Southern Ocean species, Karlodinium conicum, contained a novel poorly hemolytic karlotoxin analogue (KmconicumTx, 2.8 pg · cell−1). The hemolytic potency (HD50%) of the Australian karlotoxins were as follows: KmSwanTx 2‐1 (65.9 ± 4.8 ng) and KmSwanTx 2‐2 (63.4 ± 3.7 ng), KmHuonTx 2 (343 ± 4.9 ng), and KmconicumTx (>4,000 ng). Species from the closely related genera Takayama (T. helix, T. tasmanica, T. tuberculata), Karenia (K. asterichroma, K. brevis, K. mikimotoi, K. papilionacea, K. umbella), and Karlodinium (Ka. australe, Ka. antarcticum, Ka. ballantinum, Ka. corrugatum, Ka. decipiens) were all consistently negative for karlotoxin production. Brevetoxin (PbTx) was only detected in K. brevis, and hemolytic activity was only observed in Ka. veneficum strains.

Marine microalgae attack and feed on metazoans

“…Thus, K. armiger seems to use toxins to stun and feed on prey in a similar manner to K. veneficum preying on cryptophytes (Sheng et al, 2009), but that the range of prey types extends to diverse metazoan organisms. This difference in prey specificity may indicate that the activity of the toxins produced by K. armiger differ from the well-known Karlotoxins produced by K. veneficum (Deeds et al, 2002;Mooney et al, 2009;Sheng et al, 2009). Karlotoxin specificity has been shown to be related to the sterol composition of cell membranes (Deeds et al, 2002).…”

“…Karlotoxins also have anti-grazing properties towards important microzooplankton and copepod grazers (Adolf et al, 2007;Waggett et al, 2008). Evidence suggests that fish kills because of K. veneficum, are caused indirectly by cell-rupture and toxin release upon contact with the gills Mooney et al, 2009), as opposed to the non-toxic heterotrophic dinoflagellate Pseudopfiesteria shumwaye that may kill fish larvae by active tube-feeding (Vogelbein et al, 2002).…”

“…The widespread species K. veneficum represents one of the most problematic and well-studied toxic bloom-forming microalgae known (Garcés et al, 2006;Place et al, 2008;Mooney et al, 2009;Calbet et al, 2011) and has been recognised for its ichtyotoxicity (toxic to fish) since the 1950s (Braarud, 1957). Several aspects of its biology (Adolf et al, 2008), toxins (Deeds et al, 2002;Van Wagoner et al, 2010) and harmful effects on fish (Nielsen, 1993) have been described in detail and were recently reviewed (Place et al, 2011).…”

Marked deleterious changes in the condition, growth and maturity schedules of Acanthopagrus butcheri (Sparidae) in an estuary reflect environmental degradation

“…This problem has become exacerbated over the last three decades by a decline in freshwater discharge (Western Australian Department of Water, 2014), resulting from reduced rainfall (Australian Bureau of Meteorology, 2014), and a greater penetration of the salt wedge upstream. This has led to elevated nutrient concentrations (Robson et al, 2008) and a greater prevalence of prolific algal blooms (Twomey and John, 2001), some of which are toxic (Orr et al, 2004;Mooney et al 2009) and have resulted in an increased prevalence of 'kills' of fish species such as the black bream Acanthopagrus butcheri (Smith, 2006;Kristiana et al, 2012).…”

Ichthyotoxicity of gymnodinioid dinoflagellates: PUFA and superoxide effects in sheepshead minnow larvae and rainbow trout gill cells

“…A full understanding of the fishkilling mechanism has been elusive however. In the absence of a specific toxin, such as brevetoxin in Karenia brevis and karlotoxin in Karlodinium veneficum (Mooney et al 2009), research to find a toxic mechanism in other dinoflagellates such as Karenia mikimotoi has focused on lipids such as polyunsaturated fatty acids (PUFAs) (Arzul et al 1998, Fossat et al 1999, Gentien et al 2007). Cold-adapted algae often have elevated levels of PUFAs to maintain cellular function, as these molecules remain fluid at lower temperatures (Valentine & Valentine 2004).…”