Please Note:

The Library Open Repository will be moving to a new authentication system on the 1st of November.

From this date onwards, account holders will be required to login using their University of Tasmania credentials.
If your current repository username differs from your University username, please email E.Prints@utas.edu.au so we can update these details on your behalf.

Due to the change, there will be a short outage of the repository from 9am on the morning of the 1st of November

Library Open Repository

Mechanisms of ichthyotoxicity by gymnodinioid dinoflagellates (Kareniaceae, Dinophyta) : the role of lipids, toxins and reactive oxygen species

Downloads

Downloads per month over past year

Mooney, B (2009) Mechanisms of ichthyotoxicity by gymnodinioid dinoflagellates (Kareniaceae, Dinophyta) : the role of lipids, toxins and reactive oxygen species. PhD thesis, University of Tasmania.

[img] PDF (Whole thesis)
whole_MooneyBen...pdf | Request a copy
Full text restricted
Available under University of Tasmania Standard License.

[img] PDF (Whole thesis (published material removed))
whole_Mooney200...pdf | Request a copy
Full text restricted
Available under University of Tasmania Standard License.

Abstract

Fragile, athecate, gymnodinioid dinoflagellates from the family Kareniaceae have long
been associated with mortalities of finfish, with the principal site of damage
consistently observed at the gills. The agents i~vestigated as potentially responsible
for ichthyotoxicity included lipids, particularly the polyunsaturated fatty acid (PUF A)
octadecapentaenoic acid (OP A), the recently characterized polyketide phycotoxin
karlotoxin (KmTx), and reactive oxygen species (ROS), measured as superoxide (0£).
Lipid composition of 8 species (Karenia brevis, K m(kimotoi, K papilionacea, K
umbella; Karlodinium decipiens, Ka. veneficum; Takayama helix, T. tasmanica)
revealed fatty acids dominated by the putative lipid phycotoxin OPA and
docosahexaenoic acid (DHA). Sterol composition consisted mainly of novel 4-methyl
Ii 8<14
) sterols, brevesterol and gymnodinosterol, in all species except Karenia
papilionacea, which contained 4-des~ethyl Ii 8<14
) sterols.
Survey of 15 species revealed only 2 closely related species, Karlodinium veneficum
and Karlodinium conicum, produce karlotoxin, but with variable hemolytic activity in
different strains. The hemolytic potency (HD50%) ofkarlotoxins was: KmswanTx 2-1
(65.9 ± 4.8 ng) and KmSwanTx 2-2 (63.4 ± 3.7 ng); KmHuonTx 2 (343.± 4.9 ng) and
Klllcomcum Tx (>4000ng). Karlotoxin was shown to be algicidal towards Karenia ,
papilionacea, reinforcing that 4-desmethyl sterol containing cells, such as cholesterol
in fish gill membranes, are vulnerable.
Larval finfish bioassays confirmed karlotoxin was cell bound as ichthyotoxicity
increased upon cell lysis. Lysed low density Karlodinium veneficum cultures grown
under phosphorus limited conditions cause,cl quicker fish mortality than those cultured
in replete nutrient conditions. Pure karlotoxins were toxic to sheepshead minnow
larvae, the lethal dose (LDso) was: KmHuonTx 2 508.2 ng/mL; KmswanTx 2-1 563.2
ng/mL, and Klllcomcum Tx 762.4 ng/mL.
Purified monogalactosyl diglyceride (MGDG) lipids containing OPA exclusively, or
an octatetraenoic (OT A) and docosahexaenoic (DHA) acid mixture, caused no larval
finfish mortality at 120 mg/L. Superoxide production from 15 species ofKareniaceae
was 10 times less than those produced by the well-known ichthyotoxic raphidophyte
Chattonella marina. The singular or synergistic application of lipids, superoxide and
sub-lethal karlotoxin revealed no ichthyotoxicity with any paired combination, except
when lipids were combined with karlotoxin.
Except for the demonstrated role of karlotoxin in Karlodinium veneficum and Ka.
conicum and brevetoxin in Karenia brevis, the fish-killing mechanism by other
gymnodinioid dinoflagellates remains largely unresolved. The purported toxin in
Karenia mikimotoi, gymnocin, was not detected. Reactive oxygen species in
Kareniaceae were quantitatively less important than in fish-killing raphidophytes and
bioassays using naturally occurring forms of OPA and OTA indicated that PUFA were
non-toxic to sheepshead minnow larvae.

Item Type: Thesis (PhD)
Copyright Holders: The Author
Copyright Information:

Copyright 2009 the Author - The University is continuing to endeavour to trace the copyright owner(s) and in the meantime this item has been reproduced here in good faith. We would be pleased to hear from the copyright owner(s).

Additional Information:

Chapter two appears to be the equivalent of the peer reviewed version of the following article: Mooney, B. D., Nichols, P. D., de Salas, M. F. and Hallegraeff, G. M. (2007), Lipid, fatty acid and sterol composition of eight species of Kareniaceae (Dinophyta): chemotaxonomy and putative lipid phycotoxins, J. Phycol. 43: 101-111, which has been published in final form at 10.1111/j.1529-8817.2006.00312.x. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.

Chapter three appears to be the equivalent of the peer reviewed version of the following article: Mooney, B. D., De Salas, M. F., Hallegraeff, G. M. and Place, A. R. (2009), Survey for karlotoxin production in 15 species of gymnodinioid dinoflagellates (Kareniaceae, Dinophyta), J. Phycol. 45: 164-175, which has been published in final form at 10.1111/j.1529-8817.2008.00630.x. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.

Chapter five appears to be the equivalent of a post-print article finally published as: Mooney, B. D., Hallegraeff, G. M. and Place, A. R. 2010, lchthyotoxicity of four species of gymnodinioid dinoflagellates (Kareniaceae, Dinophyta) and related karlotoxins, Harmful algae, 9(6), 557-562.

Chapter six may be the equivalent of a pre-print article finally published as: Mooney, B. D.; Dorantes-Aranda, J.J.; Place, A.R.; Hallegraeff, G.M.; 2011, Ichthyotoxicity of gymnodinioid dinoflagellates: PUFA and superoxide effects in sheepshead minnow larvae and rainbow trout gill cells, Mar Ecol Prog Ser 426: 213–224. doi: 10.3354/meps09036

Date Deposited: 03 Feb 2015 03:04
Last Modified: 11 Mar 2016 05:53
Related URLs:
Item Statistics: View statistics for this item

Actions (login required)

Item Control Page Item Control Page
TOP