Pigments and fatty acids of marine raphidophytes: A chemotaxonomic re-evaluation

The patterns of occurrence of photosynthetic pigments and fatty acids among seven available species (11 strains) of marine raphidophytes were determined and used as chemotaxonomic markers. All currently recognized genera of marine raphidophytes were included for analysis: that is, Chattonella, Fibrocapsa, Heterosigma, Olisthodiscus and Haramonas. The characteristic pigment composition was shown to be chlorophyll a, chlorophylls c₁ and/or c₂, fucoxanthin as the major carot-enoid, β,β-carotene and any or all of zeaxanthin, violaxanthin and an auroxanthin-like pigment as the minor carotenoids. The carotenoid composition of all marine raphidophyte genera investigated was virtually the same, except in Fibrocapsa and Haramonas, which differed due to the occurrence of fucoxanthinol and 19′-butanoyloxyfucoxanthin, respectively. These fucoxanthin derivatives, in addition to fucoxanthin, have potential chemotaxonomic use for differentiating the two species. In all 11 strains, 15 fatty acids (saturated, mono-unsaturated and polyunsaturated) were determined. Significant taxonomic distinctions between genera were reflected by their fatty acid profiles. A rapid key for the differentiation of genera, in addition to morphological features, may be the absence of the 18:4 fatty acid in Olisthodiscus; presence of 18:5 in Heterosigma; the presence of fucoxanthinol in Fibrocapsa and presence of 19′-butanoyloxyfucoxanthin in Haramonas.     

COMPARATIVE EFFECTS OF LIGHT ON PIGMENTS OF TWO STRAINS OF EMILIANIA HUXLEYI (HAPTOPHYTA)1

Calcifying and a noncalcifying strains of Emiliania huxleyi were cultured in nutrient replete turbidostats under a photon flux density (PFD) gradient from 50 to 600 μmol E·m^?2·s^?1. For both strains, growth was PFD‐saturated at 300 μmol E·m^?2·s^?1. The strains, although with clearly different physiological properties due to the presence or absence of calcification, showed the same trends and magnitude of change in their pigment compliment as a function of PFD. Light‐controlled pigment composition and the trends of change in pigment composition were identical in both strains. Fucoxanthin (Fuco) was the major carotenoid in the calcifying strain, while in the noncalcifying strain this role was assumed by 19′ hexanoyloxyfucoxanthin (19 Hex). The photoprotective pigments and 19 Hex, normalized to chl a, increased with increasing light, while chl a content per cell and chl c's and Fuco, normalized to chl a, decreased with increasing PFD. The sum of all carotenoids normalized to chl a was remarkably similar in all PFDs used. Collectively, our results suggest that 19 Hex was synthesized from Fuco with light as a modulating factor and that the total amount of carotenoids is strain‐specific and synthesized/catabolized in tandem with chl a to a genetically predefined level independent of PFD.     

IMPROVED DETECTION AND CHARACTERIZATION OF FUCOXANTHIN‐TYPE CAROTENOIDS: NOVEL PIGMENTS IN EMILIANIA HUXLEYI (PRYMNESIOPHYCEAE)1

A new atmospheric pressure chemical ionization mass spectrometry (APCI‐LC/MS) method improved detection and aided characterization of fucoxanthin related carotenoids, revealing the coccolithophorid Emiliania huxleyi (Lohm.) Hay et Mohler (strain MBA 92, Plymouth) to contain a wider range of acyloxyfucoxanthins than reported previously. The diversity is confirmed as arising from differences in the length of the alkanoic acid substituent esterified at position C‐19′. Acyloxyfucoxanthins with substituents of between four and eight carbons at the C‐19′ position have been detected in a culture of Emiliania huxleyi, where previously only 19′‐butanoyloxyfucoxanthin and 19′‐hexanoyloxyfucoxanthin have been reported in the literature. Novel fucoxanthinol derivatives were also found. The detection of these novel carotenoids in Emiliania huxleyi permits detailed studies of the impact of environmental factors on individual components of the complex pool of fucoxanthin‐type carotenoids in this organism.     

PHOTOSYNTHETIC PIGMENT AND GENETIC DIFFERENCES BETWEEN TWO SOUTHERN OCEAN MORPHOTYPES OF EMILIANIA HUXLEYI (HAPTOPHYTA)1

The widespread coccolithophorid Emiliania huxleyi (Lohmann) W. W. Hay et H. Mohler plays a pivotal role in the carbon pump and is known to exhibit significant morphological, genetic, and physiological diversity. In this study, we compared photosynthetic pigments and morphology of triplicate strains of Southern Ocean types A and B/C. The two morphotypes differed in width of coccolith distal shield elements (0.11–0.24 μm, type A; 0.06–0.12 μm, type B/C) and morphology of distal shield central area (grill of curved rods in type A; thin plain plate in type B/C) and showed differences in carotenoid composition. The mean 19′‐hexanoyloxyfucoxanthin (Hex):chl a ratio in type B/C was >1, whereas the type A ratio was <1. The Hex:fucoxanthin (fuc) ratio for type B/C was 11 times greater than that for type A, and the proportion of fuc in type A was 6 times higher than that in type B/C. The fuc derivative 4‐keto‐19′‐hexanoyloxyfucoxanthin (4‐keto‐hex) was present in type A but undetected in B/C. DNA sequencing of tufA distinguished morphotypes A, B/C (indistinguishable from B), and R, while little variation was observed within morphotypes. Thirty single nucleotide polymorphisms were identified in the 710 bp tufA sequence, of which 10 alleles were unique to B/C and B morphotypes, seven alleles were unique to type A, and six alleles were unique to type R. We propose that the morphologically, physiologically, and genetically distinct Southern Ocean type B/C sensu Young et al. (2003) be classified as E. huxleyi var. aurorae var. nov. S. S. Cook et Hallegr.     

PIGMENT COMPOSITION AND rbcL SEQUENCE DATA FROM THE SILICOFLAGELLATE DICTYOCHA SPECULUM: A HETEROKONT ALGA WITH PIGMENTS SIMILAR TO SOME HAPTOPH Y TES

Monophyly of plastids in the morphologically diverse heterokont algae has rarely been questioned. However, HPLC analysis revealed that the pigment composition of the silicoflagellate Dictyocha speculum Ehrenberg is similar to that observed in a group of haptophytes (“type 4”sensu Jeffrey and Wright 1994 . Dictyocha speculum and type 4 haptophytes possess acylfucoxanthins (19′-butanoyloxy- and 19′-hexanoyloxyfucoxanthin) in addition to fuco-, diadino-, and diatoxanthin and chl a, c, and c₃. The pigment composition of two pedinellids (Apedinella radians[Lohmann] Campbell and Mesopedinella arctica Daugbjerg), a sister group to D. speculum, deviates from D. speculum by lack of chl c ₃ and acylfucoxanthins. The distinct pigment composition suggested that plastid evolution in D. speculum differs from that of other heterokont algae. This prompted determination of the plastid-encoded rbcL gene from D. speculum to gain further insight into the evolutionary history of plastids in heterokont algae and haptophytes. A phylogenetic inference based on parsimony, maximum likelihood, and LogDet transformation methods included 35 heterokonts, 19 haptophytes, 8 red algae, and 1 cryptomonad. Three proteobacteria possessing type I RUBISCO were used to root the tree. In phylogenetic analyses, D. speculum was closely related to Rhizochromulina sp. and pedinellids, despite the latter possessing a different pigment composition. Surprisingly, the Dictyochophyceae clustered outside the lineage of heterokont algae but not within the haptophytes. Hence, analyses deduced from rbcL sequences indicated that the plastids in heterokont algae might have a more complex evolutionary history and that the shared pigment composition in D. speculum and type 4 haptophytes could be explained by convergent evolution or gene transfer. The pigment composition in D. speculum may have implications for pigment-based characterization of phytoplankton community structure in natural samples.     

The pigment composition of Phaeocystis antarctica (Haptophyceae) under various conditions of light,temperature, salinity,and iron

The pigment composition of Phaeocystis antarctica was monitored under various conditions of light, temperature, salinity, and iron. 19′‐Hexanoyloxyfucoxanthin (Hex‐fuco) always constituted the major light‐harvesting pigment, with remarkably stable ratios of Hex‐fuco‐to‐chl a under the various environmental conditions. Increased pigment‐to‐chl a ratios at low irradiance confirmed the light‐harvesting function of Fucoxanthin (Fuco), 19′‐Hexanoyloxy‐4‐ketofucoxanthin (Hex‐kfuco), 19′‐butanoyloxyfucoxanthin (But‐fuco), and chl c2 and c3. Increased pigment‐to‐chl a ratios at high irradiance, low iron concentrations, and to a lesser extent at high salinity confirmed the photoprotective function of diadinoxanthin, diatoxanthin, and ß,ß‐carotene. Pigment ratios were not always according to expectations. The consistent increase in But‐fuco/chl at high temperature, high salinity, and low iron suggests a role in photoprotection rather than in light harvesting. Low Hex‐kfuco/chl ratios at high salinity were consistent with a role as light harvester, but the high ratios at high temperature were not, leaving the function of Hex‐kfuco enigmatic. Dedicated experiments were performed to test whether or not the light‐harvesting pigment Fuco could be converted into its structural relative Hex‐fuco, and vice versa, in response to exposure to light shifts. Rapid conversions could not be confirmed, but long‐term conversions cannot be excluded. New pigment ratios are proposed for chemotaxonomic applications. The ratios will improve pigment‐based diagnosis of algal species in waters dominated by P. antarctica.     

Multinuclear magnetic resonance studies of monomers and dimers containing 2'-fluoro-2'-deoxyadenosine

A series of 2′-fluorinated adenosine compounds, dAfl, dAflp, pdAfl, dAfl-A, A-dAfl, and dAfl-dAfl, have been investigated by nmr spectroscopies. The ¹H-, ¹⁹F-, and ³¹P-nmr data provide structural information from different parts of these moleucles. The pK_a of the phosphate group of these two 2′-fluoro-2′-deoxyadenosine monophosphates was found to be the same as that of hte parent adenosine monophosphate. As for the pentose conformation, the ³E population is greatly increased as a result of the fluorine substitution at the C_2′ position. However, the populations of conformers of gg (C_4′-C_5′) and g′g′ (C_5′-O_5′) and the average angle ?′(C_3′-O_3′) of the 2′-fluoro compounds remain unchanged as compared to the natural riboadenosine monomer and dimer (A-A). Thefefore, the backbone conformation of the 2′-fluoro-2′-deoxy-adenosine, its monophosphates and dimers, resembles that of RNA. The extent of base-base overlapping in these 2′-fluoro-2′-deoxy-adenosine-containing dimers is also found to be similar to or even greater than A-A. Thus, the conformations of these compounds can be considered as those in the RNA family. These fluorocompounds also serve as models for a careful study on the ¹⁹F-nmr in nucleic acid. The ¹⁹F chemical-shift values are sensitive to the environment of the fluorine atom such as ionic structure of the neighboring group(s) (phosphate of base), solvation, and ring-ruccent anisotropic effect from the base(s). Qualitatively, the change of the ¹⁹F chemical-shift values (up to 2 ppm) is much larger than that of ¹H-nmr (up to 0.5 ppm) in the dimers. Using dAfl·poly(U), poly(dAfl)·poly(dAfl), and poly(dAfl)·poly(U) helix–coil transition as model systems, the linewidth of ¹⁹F in dAfl- residues reflects effectively the mobility of the unit in the nucleic acid complex as calibrated by uv data and by ¹H-nmr. Therefore, application of ¹⁹F-nmr spectroscopy on fluorine-substituted nucleic acid can also be used to detect nucleic acid-nucleic acid interaction in complicated systems.     

Sioxanthin,a novel glycosylated carotenoid,reveals an unusual subclustered biosynthetic pathway

Members of the marine actinomycete genus Salinispora constitutively produce a characteristic orange pigment during vegetative growth. Contrary to the understanding of widespread carotenoid biosynthesis pathways in bacteria, Salinispora carotenoid biosynthesis genes are not confined to a single cluster. Instead, bioinformatic and genetic investigations confirm that four regions of the Salinispora tropica CNB‐440 genome, consisting of two gene clusters and two independent genes, contribute to the in vivo production of a single carotenoid. This compound, namely (2′S)‐1′‐(β‐D‐glucopyranosyloxy)‐3′,4′‐didehydro‐1′,2′‐dihydro‐φ,ψ‐caroten‐2′‐ol, is novel and has been given the trivial name ‘sioxanthin’. Sioxanthin is a C₄₀‐carotenoid, glycosylated on one end of the molecule and containing an aryl moiety on the opposite end. Glycosylation is unusual among actinomycete carotenoids, and sioxanthin joins a rare group of carotenoids with polar and non‐polar head groups. Gene sequence homology predicts that the sioxanthin biosynthetic pathway is present in all of the Salinispora as well as other members of the family Micromonosporaceae. Additionally, this study's investigations of clustering of carotenoid biosynthetic genes in heterotrophic bacteria show that a non‐clustered genome arrangement is more common than previously suggested, with nearly half of the investigated genomes showing a non‐clustered architecture.     

Origin of the plastid in the anomalously pigmented dinoflagellate Gymnodinium mikimotoi (Gymnodiniales, Dinophyta) as inferred from phylogenetic analysis based on the gene encoding the large subunit of form I-type RuBisCO

The dinoflagellate Gymnodinium mikimotoi Miyake et Kominami ex Oda possesses an anomalously pigmented plastid which contains 19′‐hexanoyloxyfucoxanthin, 19′‐butanoyloxyfucoxanthin and fucoxanthin instead of peridinin as the major carotenoids. Previously, we have shown that the plastid of G. mikimotoi belongs to the rhodoplast lineage as inferred from phylogenetic analyses based on the amino acid sequences deduced from psbA and psaA and the nucleotide sequence of the plastid small subunit ribosomal RNA. Furthermore, in the present study, we cloned and sequenced an additional representative plastid gene, rbcL, encoding the large subunit of ribulose 1–5 bisphosphate carboxylase/oxygenase (RuBisCO LSU) from G. mikimotoi. The amino acid sequence deduced from the rbcL gene of G. mikimotoi apparently revealed the conventional form I RuBisCO LSU, which is present in most photosynthetic organisms, and not the divergent form II existing in typically pigmented dinofl age Nates with plastids containing peridinin as the main carotenoid. This finding supports the hypothesis that the origins of the plastids in G. mikimotoi and peridinin‐type dinoflagellates are not related to each other. Molecular phylogenetic analysis based on the amino acid sequence deduced from the rbcL gene further showed that the plastid of G. mikimotoi belongs to the rhodoplast lineage. In particular, G. mikimotoi clustered with haptophytes in the phylogenetic tree. From this result, two hypotheses with respect to the origin of the plastid in G. mikimotoi can be proposed: G. mikimotoi may have engulfed a haptophyte‐like cell (tertiary symbiosis) or englulfed a rhodophyte‐like cell that was closely related to the origin of the plastid in the haptophyte (secondary symbiosis).     

Chloroperoxidase production by Caldariomyces fumago biofilms

Chloroperoxidase (CPO) is a versatile enzyme, which is secreted by the marine fungus Caldariomyces fumago (Leptoxyphium fumago). However, the application of the enzyme is hampered by its high price, which is due to the costly, labor‐intensive purification process. One challenge of the downstream process is the removal of a coproduced black pigment that forms a complex with the active enzyme. While strain development can be considered as an option to reduce the synthesis of the interfering pigment, the metabolism of the microorganism can be altered alternatively by using the biofilm growth mode of the fungus. The aim of this study was to reduce pigment formation during CPO synthesis. We investigated for the first time CPO production during C. fumago biofilm growth initiated through the presence of different microstructured stainless steel surfaces (material number: 1.4571; AISI 316Ti). CPO production by C. fumago was similar when grown as a biofilm or in suspension, whereas pigment formation was drastically reduced by cells grown on moderately structured surfaces (R_a = 0.13 ± 0.02 μm). The possibilities of biofilm growth for changing cell properties and for continuous fermentation are discussed.     

Synthesis of Novel 3′-Hydroxymethyl 5′-Deoxythreosyl Phosphonic Acid Nucleoside Analogues as Potent Antiviral Agents

A very efficient synthetic route to novel 3′-hydroxymethyl 5′-deoxythreosyl phosphonic acid nucleosides was described. The discovery of threosyl phosphonate nucleoside (PMDTA, EC₅₀ = 2.53 μM) as a potent antihuman immunodeficiency virus (anti-HIV) agent has led to the synthesis and biological evaluation of 3′-modified 5′-deoxy versions of the threosyl phosphonate nucleosides. 3′-Hydroxymethyl 5 ′-deoxythreosyl phosphonic acid nucleoside analogues 15, 19, 24, and 28 were synthesized from 1,3-dihydroxyacetone and tested for anti-HIV activity as well as cytotoxicity. The adenine analogue 19 exhibits moderate in vitro anti-HIV-1 activity (EC₅₀ = 10.2 μM).     

MORPHOLOGY,PLOIDY, PIGMENT COMPOSITION,AND GENOME SIZE OF CULTURED STRAINS OF PHAEOCYSTIS (PRYMNESIOPHYCEAE)1

We examined cell morphology, ploidy level, cell size, pigment composition, and genome size in 16 cultured strains of Phaeocystis Lagerheim. Two strains originated from the Antarctic, 3 from the tropical Western Atlantic, and 11 from temperate regions (Eastern Atlantic, English Channel, North Sea, and Mediterranean Sea). Thirteen strains made colonies morphologically similar to P. glo-bosa Scherffel, whereas three never formed colonies under any circumstances. Five-rayed star-like structures with filaments were observed in 11 strains. In several strains, two ploidy levels were observed, one (haploid) linked to flagellates and one (diploid) linked to colonies. Cell size did not appear to be a very good criterion for distinguishing strains since size distributions overlapped. Pigment analysis by reversed-phase-high-performance liquid chroma-tography allowed the strains to be grouped into three clusters that differed from each other mainly by the relative proportions of three carotenoids: fucoxanthin, 19′-hex-anoyloxyfucoxanthin, and diadinoxanthin. All strains contained low levels of 19′-butanoyloxyfucoxanthin. Differences in genome size measured by flow cytometry delimited at least five groups. On the basis of both pigment composition and genome size, six clusters were defined, one corresponding to an Antarctic species (possibly P. antarc-tica), one to P. globosa, and the rest probably to several yet-undescribed species or subspecies. Two main conclusions emerge from this study. First, the taxonomy of the genus Phaeocystis needs to be clarified through a combination of morphological, biochemical, and molecular studies. Second, sexuality is a prevalent phenomenon in Phaeocystis, but controls of the sexual cycle are most likely strain-dependent.     

Genetic effects of PRNP gene insertion/deletion (indel) on phenotypic traits in sheep

Prion protein (PRNP) gene is well known for affecting mammal transmissible spongiform encephalopathies (TSE), and is also reported to regulate phenotypic traits (e.g. growth traits) in healthy ruminants. To identify the insertion/deletion (indel) variations of the PRNP gene and evaluate their effects on growth traits, 768 healthy individuals from five sheep breeds located in China and Mongolia were identified and analyzed. Herein, four novel indel polymorphisms, namely, Intron-1-insertion-7bp (I1-7bp), Intron-2-insertion-15bp (I2-15bp), Intron-2-insertion-19bp (I2-19bp), and 3′ UTR-insertion-7bp (3′ UTR-7bp), were found in the sheep PRNP gene. In five analyzed breeds, the minor allelic frequencies (MAF) of the above indels were in the range of 0.008 to 0.986 (I1-7bp), 0.113 to 0.336 (I2-15bp), 0.281 to 0.510 (I2-19bp), and 0.040 to 0.238 (3′ UTR-7bp). Additionally, there were 15 haplotypes and the haplotype ‘I_I2-15bp-D_3’UTR-7bp-D_I2-19bp-D_I1-7bp’ had the highest frequency, which varied from 0.464 to 0.629 in five breeds. Moreover, association analysis revealed that all novel indel polymorphisms were significantly associated with 13 different growth traits (P < 0.05). Particularly, the influences of I2-15bp on chest width (P = 0.001) in Small Tail Han sheep (ewe), 3′ UTR-7bp on chest circumference (P = 0.003) in Hu sheep, and I2-19bp on tail length (P = 0.001) in Tong sheep, were highly significant (P < 0.01). These findings may be a further step toward the detection of indel-based typing within and across sheep breeds, and of promising target loci for accelerating the progress of marker-assisted selection in sheep breeding.     

SEPARATION OF CHLOROPHYLLS c1c2, AND c3 OF MARINE PHYTOPLANKTON BY REVERSED-PHASE-C18-HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY1

We separated chlorophylls c₁ c₂, and c₃ of marine phytoplankton together with other pigments by a modification of the commonly applied reversed-phase-C18-high-performance liquid chromatography (RP-C18-HPLC) method. However, the chlorophyll c-like pigment 2,4, Mg-divinylpheoporphyrin as monomethyl ester, co-eluted with chlorophyll c₁. The method involves optimization of the mobile phase by using a very high ion strength solvent in combination with a high carbon loaded RP-C18 column. Fingerprints of the various taxonomic groups of algae can thus be developed in a single run, including separation of the carotenoids lutein and zeaxanthin.     

Red Pigment Formation by the Reaction of Oxidized Ascorbic Acid and Protein in a Food Model System of Low Moisture Content

Ascorbic acid-protein mixtures of low moisture content stored for 2~3 days in aerobic conditions at 60°C produced a red coloration, which was shown to have resulted from an amino-carbonyl reaction of oxidized ascorbic acid (dehydroascorbic acid, DHA) by the facts that DHA-casein or ovalbumin systems yielded a rapid red coloration in low moisture conditions as well as in an ethanol suspension. Zein showed only a weak red coloration with DHA. An apparent decrease in the free amino group, as determined by the TNBS method, was observed to be associated in parallel with the red pigment formation. The electrophoretic pattern of ovalbumin changed significantly upon incubation with DHA, together with the formation of the red pigment. The red pigment extracted from a DHA-casein system showed an absorption spectrum, TLC Rf value, and hydrolyzed products (DHA and scorbamic acid) identical to those of 2,2′-nitrilo di-2(2)-deoxy-l-ascorbic acid mono ammonium salt, produced from DHA and amino acid. Formation of the red pigment was also observed in the reaction of DHA with N_α-acetyl lysine. These results indicate that the ε-amino group of lysine in protein can be attributed to the formation of a red pigment identical with NDA.     

Effects of iron concentration on pigment composition in Phaeocystis antarctica grown at low irradiance

Interpretation of photosynthetic pigment data using iterative programs such as CHEMTAX are widely used to examine algal community structure in the surface ocean. The accuracy of such programs relies on understanding the effects of environmental parameters on the pigment composition of taxonomically diverse algal groups. Phaeocystis antarctica is an important contributor to total autotrophic production and the biogeochemical cycling of carbon and sulfur in the Southern Ocean. Here we report the results of a laboratory culture experiment in which we examined the effects of ambient dissolved iron concentration on the pigment composition of colonial P. antarctica, using a new P. antarctica strain isolated from the southern Ross Sea in December 2003. Low-iron (<0.2 nM dissolved Fe) filtered Ross Sea seawater was used to prepare the growth media, thus allowing sub-nanomolar iron additions without the use of EDTA to control dissolved iron concentrations. The experiment was conducted at relatively low irradiance (∼20 μE m⁻² s⁻¹), with P. antarctica primarily present in the colonial form—conditions that are typical of the southern Ross Sea during austral spring. Relative to the iron-limited control treatments (0.22 nM dissolved Fe), iron addition mediated a decrease in the ratio of 19′-hexanoyloxyfucoxanthin to chlorophyll a, and an increase in the ratio of fucoxanthin to chlorophyll a. Our results also suggest that the ratio of 19′-hexanoyloxyfucoxanthin to chlorophyll c₃ (Hex:Chl c₃ ratio) may be a characteristic physiological indicator for the iron-nutritional status of colonial P. antarctica, with higher Hex:Chl c₃ ratios (>3) indicative of Fe stress. We also observed that the ratio of fucoxanthin to 19′-hexanoyloxyfucoxanthin (Fuco:Hex ratio) was highly correlated (r ² = 0.82) with initial dissolved Fe concentration, with Fuco:Hex ratios <0.05 measured under iron-limited conditions (dissolved Fe <0.45 nM). Our results corroborate and extend the results of previous experimental studies, and, combined with pigment measurements from the southern Ross Sea, are consistent with the hypothesis that the interconversion of fucoxanthin and 19′-hexanoyloxyfucoxanthin by colonial P. antarctica is used as a photo-protective or light-harvesting mechanism, according to the availability of dissolved iron.     

The response of carotenoids and chlorophylls during virus infection of Emiliania huxleyi (Prymnesiophyceae)

We report the response of carotenoids and chlorophylls during 120 h time series virus infection experiments of the marine coccolithophorid Emiliania huxleyi (Lohm.) Hay et Mohler culture. The response of individual carotenoids to infection varied: Diatoxanthin (Dtx) increased rapidly relative to chlorophyll-a, whereas diadinoxanthin (Ddx) and β-carotene showed a rapid decrease and fucoxanthin and 19′hexanoyloxyfucoxanthin a slight increase. The response of the individual carotenoids reflects their role in epoxy/de-epoxidation cycling, antioxidant protection, biosynthetic conversion and vulnerability to photooxidative destruction. We observed for the first time the operation of the diadinoxanthin cycle occurring in response to viral infection in E. huxleyi with the de-epoxidation ratio (Dtx / (Dtx + Ddx)) increasing exponentially with time (R² = 0.92) and decreasing exponentially with F_V / F_M (R² = 0.97). Our findings contribute to our understanding of the conversion and fate of key biochemical cell constituents in algae and are important in understanding the physiological stress response to virus infection.     

Insights into marine otter (Lontra felina) distribution along the Peru coastline

The marine otter (Lontra felina) has a patchy distribution associated with rocky coastlines along the Pacific coast of South America. In Peru marine otters are found from La Libertad (8°04′S) to Tacna (18°09′S), however, few studies have assessed its population and conservation status. To assess marine otters' current distribution along the Peru coastline, we conducted visual surveys and collected environmental characteristics such as human presence and habitat type. We surveyed 20 locations from five regions where otter presence was based on signs of detection (spraints, food leftovers, tracks, or direct observations). In addition, data on human presence, habitat type, and geographic location were also collected. Across the 20 locations, 268 sections were scanned, and marine otters were detected in 90% (n = 18) of locations and in 19% (n = 52) of sections. Spraints were the most frequent sign detected while direct observations occurred only in seven locations. Our analysis indicates habitat features play an important role in marine otter presence, with habitats with large rocks providing preferred conditions. Our study provides information on marine otter distribution along the Peru coastline that can assist in the identification of locations for focused conservation initiatives and strategies, which should be coordinated among regions to strengthen their design and implementation.     

COCCOID EUKARYOTIC MARINE ULTRAPLANKTERS WITH FOUR DIFFERENT HPLC PIGMENT SIGNATURES1

Pigment compositions of 16 coccoid eukaryotic ultraplanktonic clones isolated from coastal and oceanic waters were investigated by high-performance liquid chromatography (HPLC). Four distinct pigment signatures were observed, and clones were classified into subgroups based on the presence or absence and relative abundances of selected chlorphylls and carotenoids. The first subgroup (5 clones) was pigmented like chlorophyll b-containing higher plants and resembled true chlorophycean algae. The second subgroup (3 clones) contained chlorophyll b and relatively high levels of prasinoxanthin, a carotenoid characteristic of certain members of the Prasinophyceae (sometimes grouped as the Micromonadophyceae). The third subgroup (5 clones) was pigmented in a similar fashion but had a twofold lower prasinoxanthin-to-chlorophyll a ratio and an unidentified carotenoid. The fourth subgroup (3 clones) lacked chlorophyll b and was pigmented like certain members of the Chrysophyceae (e. g. 19′-butanoyloxyfucoxanthin-containing Pelagococcus subviridis Norris) Online diode array spectral analysis of selected clonal extracts revealed the presence of Mg 2,4-divinylphaeoporphyrin a₅ monomethyl ester-like and chlorophyll c-like pigments in representatives of the prasinophyte-like and chrysophyte like clones, respectively. These findings plus the occurrence of chlorophyll b, prasinoxanthin and 19′-butanoyloxyfucoxanthin in the North Atlantic Ocean suggest that chrysophyte- and prasinophyte-like organisms can be important biomass components of marine phytoplankton.