F. J. R. Taylor

Effects of nutrient limitation on toxin production and composition in the marine dinoflagellate Protogonyaulax tamarensis

Toxin production was measured by high pressure liquid chromatography (HPLC) when the marine dinoflagellate Protogonyaulax tamarensis (NEPCC 255) was grown under nitrogen or phosphorus limitation. The major toxins found in P. tamarensis (255) consisted of (N21-SO3-)STX (11%), (N21-SO3-)NeoSTX (44%), and [(N21-SO3-)GTX2 plus (N21-SO3-)GTX3] (20%). Total toxin content on a per cell basis was high for cultures in log phase (30 to 40 fmol cell-1) and then decreased to ca 20 fmol cell-1 as the cultures entered stationary phase. There was a gradual decrease in the toxin content per cell during nitrogen-limited stationary phase to ca 3 fmol cell-1 or less. Phosphorus-limited cultures showed a markedly different response than nitrogen-limited cultures. Toxin content in P-limited cells dramatically increased at the start of stationary phase, reaching levels 3 to 4 times that observed in control and nitrogen-limited cultures. These results cannot be explained by changes in the average cell volume. Eventhough dramatic effects on the total toxin concentration were observed in response to nutrient limitation (N or P), the toxin composition (on a percent basis) remained constant. This suggests that the individual toxin composition of a given isolate is a fixed genetic trait and not a transient response to changing environmental factors.

Variation in paralytic shellfish toxin composition within the Protogonyaulax tamaronsis/catenella species complex; red tide dinoflagellates

Abstract Unialgal isolates of the Protogonyaulax (—Gonyaulax) tamarensis/catenella species complex, a group of dinoflagellates which causes paralytic shellfish poisoning (PSP), were subjected to toxin analysis by HPLC. Protogonyaulax isolates from widely separated geographical locations were compared, including the northeastern Pacific (British Columbia and Washington State), eastern Canada, Portugal, the United Kingdom and New Zealand. Two distantly related gonyaulacoid species were also analyzed, but the presence of PSP toxins was not detected. Although Protogonyaulax isolates varied markedly in total toxin concentration and toxicity, even through the culture cycle, the toxin ratios of individual isolates were distinctive and relatively constant. No toxins were detected in the Plymouth (U.K.) isolate of P. tamarensis, from the species type locality. Two isolates from Vancouver Island (British Columbia), which were previously considered to be non-toxic according to the mouse bioassay, revealed weak toxin spectra by HPLC. Within populations from English Bay (British Columbia) the toxin profiles of tamarensoid isolates tended to be conservative. However, this was not the case for the catenelloid forms from Washington State, which displayed a greater degree of toxin heterogeneity. Significantly, there was no identifiable relationship between toxicity or toxin profiles and the morphological characteristics conventionally used to separate the two dominant morphotypes into species within this species complex.

Spring phytoplankton in the Subarctic North Pacific Ocean

The report includes quantitative and qualitative data on the phytoplankton from the First Canadian Transpacific Oceanographic Cruise from March to May 1969. Nanoplanktonic species (<20 μm) were numerically dominant and, together with nertic diatoms, made up the larger portion of the biomass at all stations outside the Western Subarctic and Alaskan Gyres, where Denticulopsis seminae predominated. The nanoplankton consisted mainly of haptophycean, dinophycean and cryptophycean flagellates. Tropical oceanic dinoflagellates and diatoms were abundant in the net samples from Station 17 in the warm Kuroshio current but absent from Stations 24–27 in the Western Subarctic Gyre, Stations 2, 37–39 in the Alaskan Gyre, in which cold water oceanic species predominated, and Stations 31 and 33, south of the Aleutians. Subsurface maxima were common on the outward bound (westerly) leg in March.

Use of high-performance liquid chromatography to investigate the production of paralytic shellfish toxins by Protogonyaulax spp. in culture

Procedures have been developed for the extraction and high-performance liquid chromatography (HPLC) analysis of paralytic shellfish poisoning (PSP) toxins from Protogonyaulax spp. grown in batch culture. Using these procedures, the toxin content of two isolates of P. tamarensis (NEPCC 183 and 255) and one isolate of P. catenella (NEPCC 355) were examined. Total toxin and individual toxin concentrations were measured for each isolate during the exponential and stationary phases of growth in batch culture. The total toxicity of each isolate as measured by HPLC analysis was found to agree with toxicity as determined by the standard mouse bioassay. Two of the isolates (255 and 355) were found to be toxic and the third (183) was non-toxic. The toxic isolates (255 and 355) both showed higher average total PSP toxin content during the exponential phase (35 and 23 fmol toxin cell-1, respectively) than during the stationary phase (21 and 8 fmol toxin cell-1, respectively). These cultures differed dramatically in their toxin composition. P. tamarensis (255) contained a large proportion of the N(21) sulfo toxins (B1, B2, C1, C2) while P. catenella (355) contained primarily Gonyautoxins 1 through 4. The percent composition of individual toxins was found to be constant throughout the growth cycle for both toxic isolates, even though the total toxin concentration varied. Our results suggest that PSP toxin profiles might be useful as chemotaxonomic indicators.

Electrophoretic variability within the Protogonyaulax tamarensis/catenella species complex: Pyridine linked dehydrogenases

Abstract Extracts from 20 isolates of the Protogonyaulax (= Gonyaulax) tamarensis/catenella species complex from diverse geographical locations, including ten contemporaneous isolates from the same geographical population, were subjected to enzyme electrophoresis. Analysis of isozyme banding patterns produced by eight pyridine-linked dehydrogenases revealed a high degree of genetic polymorphism within and between morphotypes and geographical populations. Since there was little apparent correlation between electromorphs and variants assigned provisionally to the catenelloid or tamarensoid morphotype, and because morphological intermediates exist, the presently used morphological characters used to discriminate unequivocally between P. catenella and P. tamarensis appear to be inadequate. Nevertheless, within a given morphotype, isolates from the same location were more similar than to those from elsewhere. Isozyme electrophoresis offers a means of biochemically discriminating between isolates of this species complex, for which the plate patterns are substantially the same.

The determination of total phosphorus in seawater by nitrate oxidation of the organic component

Abstract A method is presented for the determination of total phosphorus dissolved in seawater by magnesium nitrate oxidation of the organic component concomitant with depolymerization of polyphosphate residues, followed by the standard molybdate colorimetric determination of the liberated orthophosphate. This method gave 93–100% recovery of phosphorus from inorganic metaphosphate and polyphosphate, phosphate esters and anhydrides, nucleotide-P, phospholipid and phosphonates. It is shown to be superior to the perchlorate-oxidation or high-intensity u.v.-irradiation methods for quantitative P recovery from phosphonates and polyphosphates, while proving equal in P recovery to the autoclave-requiring persulfate-oxidation method.