Chroomonas Salina Research Articles

Factors affecting the large-scale production of four species of commercially important marine algae

Semi-continuous cultures of four algal food species were maintained in 80 l and 200 l vessels internally illuminated by six 80 W fluorescent lamps. At standard densities Skeletonema costatum produced the greatest average yield, equivalent to 120 l d −1 for 7–8 weeks. Chaetoceros calcitrans, Isochrysis aff. galbana (clone T. Iso.) and Chroomonas salina produced 50–60 l d −1 for 2–4 weeks. Yields for each algal species were similar from 80 l and 200 l vessels and lower when four 80 W lamps were used. The harvesting regime to achieve the above yields is evaluated.

Flow cytometry: a new method for characterization of differential ingestion, digestion and egestion by suspension feeders

Flow cytometry: a new method for characterization of differential ingestion, digestion and egestion by suspension feeders

Mitosis and cytokinesis in Chroomonas africana Meyer & Pienaar (Cryptophyceae)

Mitosis and cytokinesis have been examined in a recently described species of Chroomonas , viz. Chroomonas africana Meyer & Pienaar. A comparison between this species and the three other species in which cell division has been studied ( Chroomonas salina and two Cryptomonas spp.) has revealed certain common characteristics such as an open spindle, a chromosomal plate at metaphase and similar types of spindle microtubules with indistinct kinetochores. However, the cell division process in C. africana differs from that in the above mentioned species in that (i) the spindle microtubules maintain their association with the flagellar bases throughout mitosis, (ii) the movement of the chromatin masses at anaphase is synchronous but unequal, i.e. parts of the chromatin masses move at different rates, (iii) in late anaphase and early telophase the chromatin masses arch around the flagellar bases forming cup-shaped structures and (iv) cytokinesis is accomplished by an extension of the anterior vestibular region forming a cleavage furrow which extends posteriorly. The formation of the branched vestibular region is also described.

Values of net compensation irradiation and their dependence on photosynthetic efficiency and respiration in marine unicellular algae

Daily compensation irradiation for net photosynthetic rates (ΣIcomp) of Skeletonema costatum (Greville) Cleve, Chaetoceros ceratosporum Ostenfeld, Nitzschia sp., Thalassiosira nordenskioldii Cleve, and Chroomonas salina (Wislouch) Butcher were measured during 1979 to obtain values for use in ecological models describing compensation and critical depths of marine phytoplankton. Batch cultures of these unicellular algae were exposed to temperatures and photoperiods varying from 6° to 15°C and 8.4 to 16.0 h, conditions typical of surface water in Saanich Inlet, a fjord in Vancouver Island, British Columbia, Canada. Results obtained with S. costatum and T. nordenskioldii provided estimates of ΣIcomp varying between 1.8 and 13 J cm-2 d-1, from which a mean value of 7.0 J cm-2 d-1 was calculated for use in ecological models with neritic phytoplankton. No seasonal variation in compensation irradiation was noted because photosynthetic efficiencies, which increased as division rates increased, were balanced by respiration rates, which increased as temperature increased. Results obtained with Chaetoceros ceratosporum, Nitzschia sp., and Chroomonas salina were difficult to interpret, because respiration rates were stimulated and depressed by light, respectively, for the first two species and the last one. This light effect was greatest when cells grew under conditions of low temperature and short photoperiod. Also, under winter and spring conditions, cells of Nitzschia sp. appeared to fix CO2 in the dark and with low irradiances by mechanisms other than photosynthesis.

Comparative Ultrastructure of Two members of the Cryptophyceae assigned to the Genus Chroomonas — With Comments on their Taxonomy

Summary The micromorphology of the fresh-water strain Chroomonas sp. Pringsheim (978/2 CCAP) is compared with that of the saline strain Chroomonas salina Butcher (978/20 CCAP). Their distinctive features are related to the ultrastructure of previously described members of the Cryptophyceae whereby particular attention is directed to those which show similarities in morphology and/or name. Possible taxonomic implications of these observations are discussed with reference to the currently available definition of the genus Chroomonas .

MARINE CRYPTOMONAD STARCH FROM AUTOLYSIS OF GLYCEROL‐GROWN CHROOMONAS SALINA1

ABSTRACTThe extracellular starch released by autolysis of glycerol‐grown Chroomonas salina (Wislouch) Butcher was purified and chemically characterized. It contained 99%D‐glucose, formed a blue complex (λmax at 605 nm) with iodine, and showed an optical rotation value more positive than that of potato starch. Methylation analysis established the presence of 1,4‐ and 1,4,6‐glucoside linkages in the proportion 15:1. These properties indicate the cryptomonad starch to be an iodophilic α‐(1,4)‐glucan, composed of ca. 30% amylose with amylopectin, and broadly resembling potato, Chilomonas and other unicellular algal starches.

Concentration Requirement of glycine as nitrogen source for supporting effective growth of certain marine microplanktonic algae

Eighteen species of marine phytoplankton from 9 algal classes were tested under axenic-culture conditions for their capacity to improve phototrophic-growth performance on glycine with increasing concentration of this amino-acid serving as sole nitrogen source. Whereas all these species showed poor-to-no growth on 0.5 mM glycine, 14 species manifested considerable gain in growth-rate and yield at higher concentration levels. The highest level tested (25 mM) was generally not inhibitory and produced the best yields in these cases. Some species (notably Skeletonema costatum) showed marked reduction in the adaptation-lag period with increased glycine concentration, but Chlamydomonas palla required a very long adaptation period, which was little affected by concentration. Dunaliella tertiolecta, Emiliania huxleyi and Chroomonas salina showed sharp (albeit elevated) concentration thresholds for efficient glycine utilization. Rhodomonas lens and two cyanophycean strains, Agmenellum quadruplicatum and Anacystis marina, appeared incapable of successful growth on glycine at all concentrations tested, while the rhodophyte Porphyridium marinum displayed marginal growth. The results were insufficient to draw taxonomically general conclusions on algal-class potential for glycine utilization, but they showed unequivocally that more than 83% of phytoplankton species from 9 algal classes can utilize glycine for growth if the appropriate substrate concentration is provided.

Fecundity studies on Acartia tonsa (Copepoda: Calanoida) in standardized culture

Acartia tonsa Dana longevity and egg production data were studied over a 4-year period under standardized culture conditions. Egg-laying patterns and daily rates were evaluated as bioassay tools for measuring the nutritional value of various copepod foods, as well as assessing other aspects of environmental quality. Altogether, 337 females were observed in various aspects of this work. Experiments were performed with newly matured females in loosely covered crystallizing dishes. Fresh water and a standard concentration of algae were supplied daily, and a running daily tally was kept of the eggs produced. The effects of male copepods on egg production were analyzed. Males were either removed after the first eggs were observed or they remained with the female throughout her life span. Daily egg-laying rates of this latter group of females appeared to be more stable, but abnormal embryo development occurred if the males were not removed after fertilization. Likewise, the results of females which were not mated were studied. Life spans were shorter and egg production rates were lower than those of contemporary mated females. Unmated females were subjectively observed to be less active than their mated counterparts. The effects of continuous and temporary starvation on egg-laying were also observed. Under both normal and starved conditions, males appeared to have shorter life spans than either mated or unmated females. During starvation there were no real differences between the life spans or egg productions of mated or unmated females. Non-nutritional particulate matter was evaluated as a food source. It was ingested by the females, but did nothing to prolong the egg-laying period. Finally, the three algal components of the standard ration were evaluated. Females produced equally well with a mixed diet or with Thalassiosira pseudonana (100 μm3) or Chroomonas salina (140 μm3), the two larger species of this diet, but when Isochrysis galbana (40 μm3) was fed, females reacted as if in a starved situation.

Scanning electron microscopy and comparative micromorphology of the periplast ofHemiselmis rufescens, Chroomonassp.,Chroomonas salinaand members of the genusCryptomonas(Cryptophyceae)

Scanning electron microscopy demonstrated small numbers of longitudinal offset rows of rectangular plates in Hemiselmis rufescens Parke and Chroomonas sp. Chroomonas salina Butcher and all examined strains of Cryptomonas showed numerous rows of smaller hexagonal plates. Regular arrays of peripheral trichocysts are absent in H. rufescens and account for the smooth appearance of the cell surface. In all other described members of the Cryptophyceae two trichocysts, one beneath each corner, are typically associated with the anterior facing edges of each plate. The subapical tubular gullet of the genera Chroomonas and Cryptomonas is absent in H. rufescens where the corresponding region is marked by an oval area without plates and a slightly raised posterior rim. The two anteriorly directed flagella emerge from beneath this rim or the sac-like invagination in Chroomonas and Cryptomonas. Sections of the periplast of H. rufescens and Chroomonas sp. showed the limiting plasma membrane sandwiched between an inner a...

Isolation of an unusually stable cis-isomer of alloxanthin from a bleached autolysed culture of Chroomonas salina grown photoheterotrophically on glycerol. Observations on cis-trans isomerization of alloxanthin.

SYNOPSIS. A new carotenoid, manixanthin, was isolated from a bleached, autolysed culture of the marine cryptomonad Chroomonas salina grown on glycerol in light, after the culture showed disappearance of the chlorophylls and carotenoids normally produced. Manixanthin lacked carbonyl, ester, and epoxy groups in chemical tests, whilst its spectroscopic properties indicated a conjugated nonaene chromophore. In its chromatographic mobility, manixanthin closely resembled alloxanthin, the major normal xanthophyll of the cryptomonad. The iodine‐catalysed photostereomutation of manixanthin produced the same equilibrium mixture of cis‐isomers as that given by similar treatment of alloxanthin. This mixture of isomers completely lacked the all‐trans alloxanthin and contained ∼60% manixanthin. It was concluded that manixanthin is an unusually stable cis‐isomer of alloxanthin, and is presumably produced in the culture medium by the action of light on alloxanthin released by autolysed cells of the cryptomonad. The unusual stability of manixanthin relative to alloxanthin was investigated by effecting partial stereoisomerizations under conditions using either of heat, light, or iodine, and evidence was obtained for a series of at least 10 isomers with a trend of stability increase from alloxanthin to manixanthin. It was inferred that manixanthin may be 9,9′‐dicis‐alloxanthin.

Wax Ester Production by the Marine Cryptomonad Chroomonas salina Grown Photoheterotrophically on Glycerol

SYNOPSIS. An age‐autolyzed culture of Chroomonas salina, grown under cool‐white light with glycerol, produced waxy lipid constituting about 44% of total matter harvested. This lipid was composed of 87% wax ester, 9% triglyceride, 3% polar lipid and 1% hydrocarbon. The major wax ester species were identified by total carbon number as C26(28%), C28(35%), C30(15%). The main fatty acid components of the wax esters were 12:0 (39%), 14:0 (30%), 16:0 (14%), while the main alcohols were 14:0 (53%) and 16:0 (40%). The hydrocarbon fraction showed saturated paraffins ranging from C17 to C33, with odd‐numbered chain components predominating. No polyunsaturated components were detected in the wax ester or hydrocarbon fractions. This is the first record of wax ester production by a cryptomonad or a marine phytoplankter.

Algal carotenoids and chemotaxonomy

A qualitative and quantitative examination of the carotenoids of pure cultures of four marine microalgae, including Chroomonas salina, Vaucheria sessilis and Coccolithus huxleyi is reported. The latter contained a new, major carotenoid, and not fucoxanthin.

Effects of Interactions of Irradiance, Daylength, and Temperature on Division Rates of Three Species of Marine Unicellular Algae

Rates of light-saturated division of Thalassiosira fluviatilis and Isochrysis sp., marine unicellular algae, were regulated by temperature and daylength at 25 C, and primarily by temperature at 20 C or less. The rates for Chroomonas salina appeared to be regulated by temperature and daylength at temperatures between 10 and 25 C, with maximum effects of daylength occurring at temperatures of 20 and 25 C. Physiological mechanisms through which temperature and daylength interact to regulate division rates of unicellular algae are discussed.

Mitosis in the Crypyophyvrsr.

RECENTLY a number of papers have been published describing the fine structure of nuclear division in the algae. This interest has no doubt been stimulated by the great variety of nuclear structures found and their relevance to current discussions on algal phylogeny1–3. In the past year we have had the first detailed accounts of mitosis in the Chrysophyceae4, Xanthophyceae5, Chloromonadophyceae6, Rhodophyceae7, and Phaeophyceae8. This leaves only three classes, Prasinophyceae, Eustigmatophyceae and Cryptophyceae in which details of mitosis are unrecorded. We would like to help complete the picture of algal division by making known some recent findings about mitosis in a member of the Cryptophyceae, Chroomonas salina (Wislouch) Butcher.

Ultrastructure of the Marine Cryptomonad Chroomonas salina Cultured under Conditions of Photoautotrophy and Glycerol‐Heterotrophy*

SYNOPSIS. Chroomonas salina was cultured in seawater medium enriched with nitrate, phosphate, silicate, trace‐metal ions, and vitamins, under 3 conditions: (A) light without other organic additions (photoautotrophic); (B) light and added glycerol (photoheterotrophic); (C) in darkness but with added glycerol (chemoheterotrophic). The heterotrophic cultures were initiated from a stock maintained on glycerol in continuous darkness for 41/4 years. The autotrophic culture was initiated from a corresponding stock maintained under continuous illumination without any organic growth substrate. The fine structure of organisms from simultaneously initiated cultures was compared after 1, 2, 3, and 4 weeks of growth.“Young'’cells from the autotrophic and heterotrophic cultures of comparable maturity had no recognizable ultrastructural difference. In organisms from both the photoautotrophic and photoheterotrophic cultures there was a progressive accumulation of starch and lipid with aging, but whereas in cells from the former the production of starch was arrested after early growth and lipid was concentrated thereafter, in those from the latter both metabolites continued to be produced with consequent rapid degeneration of the cytoplasm followed by autolysis. By contrast, flagellates grown in the chemoheterotrophic culture accumulated only starch, with vacuole formation replacing the lipid stores. In all cases, the lipid bodies appeared to differ from the membrane‐bound droplets normally observed, which actually diminished with aging. Starch accumulation appeared to cause more rapid cytopathologic changes and autolysis. No evidence of chloroplastic phycobilisome‐type aggregations was noted in organisms from any culture at any age.

L-Threonine deaminase in marine planktonic algae

1. The “biosynthetic” l-threonine (deaminating) dehydratase activity of 7 marine planktonic species from 5 classes of algae showed high substrate specificity toward l-threonine, with the exception of one alga. The algal extracts deaminated l-serine and l-allothreonine at rates which were 20–25 and 5–10%, respectively, of that of l-threonine, and these reaction were inhibited by l-isoleucine. d-Threonine, d-serine, l-homoserine, and l-O-methylthreonine were ineffective as substrates. 2. Extracts of the cryptophyte Chroomonas salina were exceptional in showing about twice the activity with l-serine relative to l-threonine. The reaction with l-serine was insensitive to inhibition by l-isoleucine and differed, in several respects from that with l-threonine. It was inferred that this algal extract contains a specific l-serine deaminase in addition to the regular l-threonine deaminase. 3. The rate of deamination of l-threonine by the algal extracts was not affected by the simultaneous presence of l-allothreonine but was markedly inhibited by l-serine and l-homoserine. 4. Kinetic studies of the effects of graded concentrations of the substrate analogs at a fixed (saturating) substrate level or of substrate concentration at fixed analog levels indicated that l-serine inhibited the threonine deamination by irreversible competition with the substrate, whilst l-homoserine affected this reaction by an unknown (presumably allosteric) mechanism not involving substrate competition.

L‐THREONINE DEAMINASE IN MARINE PLANKTONIC ALGAE. II. DISULFIDE AND SULFHYDRYL GROUP REQUIREMENTS OF ENZYME ACTIVITY IN TWO CRYPTOPHYTES1

SUMMARYThe “biosynthetic”l threonine (deaminating) dehydratase of 2 cryptophytes (Chroomonas salina and Hemiselmis virescens) showed sensitive inhibition from all thiols tested (dithiothreitol, cysteine, etc.) but no effect from ascorbic acid or reduced NAD. By contrast, the enzyme activities from 5 noncryptophyceaen unicellular algae (2 cyanophytes, 1 rhodophyte, 1 diatom, 1 chlorophyte) were generally not affected by any of these reagents. The thiol reagent inhibition of the cryptophyte enzymes (1) achieved saturation with 60–70% reduction in activity, (2) was considerably reduced by pretreatment of the enzymes with l‐threonine and l‐isoleucine, and (3) was partially reversed by subsequent treatment with arsenite and exposure to air. It was deduced that such inhibitions were caused by thiol‐specific reduction of enzyme‐protein disulfide groups essential for the full expression of activity and that these groups were susceptible to ready reductive cleavage and oxidative restoration. This disulfide requirement, unique to the cryptophytes, may be the first recorded case of such a property of threonine dehydratase from all forms of life hitherto studied. The additional activity requirement of the cryptophyte enzymes for sulfhydryl groups (which requirement was common to all the algal enzymes) was confirmed (1) by the study of their sensitivity to inhibition from mercurials and disulfide‐sulfhydryl exchanging reagents, and (2) by the partial reversal of these inhibitions from subsequent treatment with dithio‐threitol. Both cryptophyte enzymes were densitized to feedback inhibition from l‐isoleucine by prior exposure to subinhibitory concentrations of HgCl2 or dithiodipyridine.

Comparative characterization of l-threonine dehydratase in seven species of unicellular marine algae

Crude extracts of the following marine algae, cultured axenically under controlled conditions, were examined for l-threonine dehydratase activity: two cyanophytes ( Agmenellum quadruplicatum, Anacystis marina), one rhodophyte ( Porphyridium cruentum), two cryptophytes ( Chroomonas salina, Hemiselmis virescens), one chlorophyte ( Tetraselmis maculata), and one diatom ( Cyclotella nana). The specific activities (4–85 mμmoles/min/mg protein) showed considerable species differences as well as significant effects from the nutritional conditions of algal culture (autotrophic vs. heterotrophic). The enzymatic production of α-ketobutyrate from l-threonine was confirmed (with 2 species) by the isolation and chromatographic identification of its 2,4-dinitrophenylhydrazone. The algal enzymes showed pH optima in the range of 8·5–9·5 and 'sigmoid' or 'paraboloid' kinetic response to threonine concentration. With the exception of C. nana, all the algal enzymes were strongly inhibited by l-isoleucine; l-Valine, EDTA, AMP, ADP, and cyclic 3′,5′-AMP had no significant effect. Several carbonyl reagents (hydrazine, hydroxylamine, etc.) strongly inhibited enzyme activity and this inhibition was reversed to varying degrees by pyridoxal 5′-phosphate. Excepting iodoacetamide, all the reagents known to modify protein sulfhydryl groups inhibited the activity strongly and these inhibitions were partially reversed by dithiothreitol. The enzymes of C. salina and H. virescens were also strongly inhibited by dithiothreitol. These results characterized the algal enzymes generally as isoleucine-regulated, pyridoxal-phosphate requiring, allosteric threonine dehydratases similar to the corresponding 'biosynthetic' enzymes previously reported for bacteria, fungi, and higher plants. In addition, the algal enzymes appeared to require sulfhydryl groups for the expression of activity. The C. nana enzyme appeared to be insensitive to isoleucine regulation, and the cryptophyte enzymes appeared to require disulfide groups for activity.

Enhancement by Glycerol of Phototrophic Growth of Marine Planktonic Algae and its Significance to the Ecology of Glycerol Pollution

The effects of low (0.05 M) and high (0.5–1.0 M) concentrations of glycerol on the growth of 18 species of marine phytoplankters belonging to 7 algal classes were studied. The algae were grown in axenic culture in sea water enriched with nitrate, orthophosphate, silicate, trace-metal ions, vitamin B12, thiamine, biotin, and buffered at pH 7.6–7.8. Apart from a chrysomonad (Prymnesium parvum) and a cryptomonad (Chroomonas salina), none of the species showed any significant growth on glycerol in the absence of light. However, in the presence of light, glycerol enhanced the growth of 16 species, in particular members of the Chrysophyceae and Cryptophyceae, one diatom (Phaeodactylum tricornutum), one rhodophyte (Porphyridium cruentum), and one chlorophyte (Nannochloris oculata). A high concentration of glycerol was required for inducing or asserting growth enhancement of certain species, but was equally effective as the low concentration or was inhibitory to other species. The enhancement effect was observed in the growth rate and in the peak population density, which in many instances was several times that from nonglycerinated cultures and suggested photoheterotrophic growth. Some species showed obvious cytological and metabolic changes from growth on glycerol. The ecological implications of glycerol pollution of sea water are discussed.