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PubMed2005

Bromophenols, both present in marine organisms and in industrial flame retardants, disturb cellular Ca2+ signaling in neuroendocrine cells (PC12).

Bromophenols are present in polychaetes as well as in algae in marine environments including the North Sea. They are thought to cause the typical sea-like taste and flavour. The ecological function of brominated phenols is not clear yet, but they may play a role in chemical defence and deterrence [Kicklighter, C.E., Kubaneck, J., Hay, M.E., 2004. Do brominated natural products defend marine worms from consumers? Some do, most don't. Limnol. Oceanogr. 49, 430-441]. Some brominated phenols are commercially used as industrial flame retardants as, e.g., 2,4,6-tribromophenol and are suspected to disrupt the humoral system by showing thyroid hormone-like activity [Legler, I., Brouwer, A., 2003. Are brominated flame retardants endocrine disruptors? Environ. Int. 29, 879-885]. In this study 2-bromophenol (2-BP), 4-bromophenol (4-BP), 2,4-dibromophenol (2,4-DBP), 2,6-dibromophenol (2,6-DBP) and 2,4,6-tribromophenol (2,4,6-TBP), all of which are present in marine organisms, were tested. Especially 2,4-DBP and 2,4,6-TBP showed a significant effect on the Ca2+ homeostasis in endocrine cells (PC 12). The reduction of depolarization induced Ca2+ elevations by 2,4-DBP and 2,4,6-TBP and the increase of intracellular Ca2+ by both substances, partly released from intracellular stores, may suggest a link to the disrupting effect of endocrine systems by brominated phenols. 2,4-DBP was the most potent substance we tested in respect to inhibition of voltage dependent Ca2+ currents as revealed in whole cell patch clamp experiments. Brominated phenols disturb cellular Ca2+ signaling with differential efficacy, depending on the number and position of bromine.

Animals↗
PubMed2005

Dependency of copper toxicity to polychaete larvae on algal concentration.

Algae are often used as food in aquatic metal toxicity tests to maintain the well-being of test animals. Such food addition may change metal bioavailability because of the reduction of aqueous metal concentration and the increase in particle-bound metal concentration. While the importance of aqueous exposure pathway is widely recognized, few studies have determined the contribution of the dietary pathway to the overall metal toxicity to aquatic invertebrates. In this study, we determined the toxicity of both algal-bound copper alone and copper solution containing algae to the larvae of marine polychaete Hydroides elegans. Algae that had been pre-exposed to copper at up to 1024 microg l(-1), when fed to the larvae, did not cause significant abnormal larval development. However, when larvae were exposed to algal-copper mixture, percentage of normal larvae could be modeled as a logistic function of aqueous copper concentration, with a 48-h EC(50) (mean +/- S.E.) of 64.9 +/- 4.8 microg Cul(-1). When the toxicity was expressed using total copper concentration, the EC(50) ranged from 58.4 +/- 4.5 microg l(-1) in the control to 121.9 +/- 9.9 microg l(-1) in the 10(6) cells ml(-1) algal treatment. This study highlights the dependency of copper toxicity on the aqueous exposure pathway in this polychaete and the importance of considering algal binding of the metal in larval toxicological tests.

Adsorption↗
PubMed2006

Influence of biotransformation on trophic transfer of the PAH, fluoranthene.

The persistence of polycyclic aromatic hydrocarbons (PAHs) in marine sediments may be influenced by benthic invertebrate bioturbation. Through processes such as deposit-feeding and enhancement of microbial metabolic activity PAHs may be remobilized from the sediment compartment, and either transferred to organisms at higher trophic levels or to the overlying water column, both processes inevitably changing the bioavailability of the PAH. Accumulation of contaminants from one level in the food chain to the next depends on feeding rate and assimilation efficiency, two factors that basically vary with food quality and contaminant type. Though it is generally believed that pre-consumptive biotransformation will reduce bioavailability due to the more polar nature of the metabolites compared to the unchanged parent compound, theoretically the decrease in lipophilicity will increase the sediment/food desorption rate in the intestine, and some metabolites will still be lipophilic enough to be absorbed by passive diffusion. We examined the trophic transfer of the PAH, fluoranthene from two closely related polychaete species (i.e., Capitella sp. I and Capitella sp. S), differing in their biotransformation ability, to the predatory polychaete, Nereis virens. We found that N. virens fed the biotransforming species, Capitella sp. I, accumulated significantly more Flu equivalents compared to worms fed Capitella sp. S, which have a very limited biotransformation ability. The dose-specific increase in N. virens intestinal Flu concentration was approximately twice as high in worms fed Capitella sp. I (equation: gut content=7.3 x dose-3.9) compared to worms fed Capitella sp. S (equation: gut content=3.2 x dose+0.6). In addition, we measured DNA damage, using the comet assay, in N. virens intestinal cells after feeding with the two prey species. We did not detect DNA damage above 'background' levels for worms fed either of the two Capitella species, possibly due to relatively low intestinal Flu concentrations in N. virens. Our results indicate that accumulation of PAHs by infaunal organisms may play an important role in the transfer of this type of contaminant to higher trophic levels. Moreover, we observed differences in transfer potential between parent compounds and their respective metabolites, which may influence the fate of these compounds in marine ecosystems. However, from the present study it cannot be concluded whether differences in biotransformation ability among prey species can lead to different effects in their predators.

Animal Feed↗
PubMed2005

The splicing factor U2AF65 is functionally conserved in the thermotolerant deep-sea worm Alvinella pompejana.

Due to their inherent stability, thermophilic bacteria and archaea serve as important resources for biochemical and biophysical analyses of many biological processes. Unfortunately, scientists characterizing eukaryote-specific processes, such as nuclear pre-mRNA splicing, are unable to take advantage of these sources of thermostable proteins. To identify and provide a source of thermostable eukaryotic proteins, we are characterizing splicing factors in the thermotolerant deep-sea vent polychaete, Alvinella pompejana. This worm, also known as the Pompeii worm, is found in the extreme environment of deep-sea hydrothermal vents, and is one of the most thermotolerant eukaryotic organisms known. We report on detailed analyses of U2AF65, the large subunit of the U2 small nuclear ribonucleoprotein auxiliary factor, an essential splicing factor important for intron definition and alternative splicing. The cloning and characterization of Pompeii U2AF65 show it is highly similar to human U2AF65 in sequence and function and is more thermostable than the human protein when bound to RNA in vitro. Notably, Pompeii U2AF65 can restore splicing in a human extract depleted of human U2AF. We also determine that the general splicing mechanisms and signal sequences are conserved in the Pompeii worm, an annelid which has previously been uncharacterized in terms of splicing factors and signals.

Amino Acid Sequence↗
PubMed2005

Over-expression, purification and characterization of the oligomerization dynamics of an invertebrate mitochondrial creatine kinase.

Mitochondrial creatine kinase (MtCK) plays a central role in energy homeostasis within cells that display high and variable rates of ATP turnover. Vertebrate MtCKs exist primarily as octamers but readily dissociate into constituent dimers under a variety of circumstances. MtCK is an ancient protein that is also found in invertebrates including sponges, the most primitive of all multi-cellular animals. We have cloned, expressed, and purified one of these invertebrate MtCKs from a marine polychaete worm, Chaetopterus variopedatus (CVMtCK). Size exclusion chromatography and dynamic light scattering (DLS) were used to characterize oligomeric state in comparison with that of octameric chicken sarcomeric isoform (SarMtCK). At protein concentrations >1 mg/ml, CVMtCK was predominantly octameric (>90%). When diluted to 0.1 mg/ml, CVMtCK dissociated into dimers much more rapidly than SarMtCK when observed under identical conditions. The rate of dissociation for both MtCKs increased as temperature rose from 2 to 28 degrees C, and in CVMtCK, fell at higher incubation temperatures. The fraction of octameric CVMtCK at equilibrium increased with temperature and then fell. Temperature transition studies showed that octamers and dimers were rapidly interconvertible on a similar time scale. Importantly, when CVMtCK was converted to the transition state analog complex (TSAC), both size exclusion chromatography and DLS showed that there was minimal dissociation of octamers into dimers while SarMtCK octamers were highly unstable as the TSAC. These results clearly show distinct differences in octamer stability between CVMtCK and SarMtCK, which could impact function under physiological circumstances. Furthermore, the large yield of recombinant protein and high stability of CVMtCK in the TSAC suggest that this protein might be a good target for crystallization efforts.

Adenosine Diphosphate↗
PubMed2006

The role of an absolutely conserved tryptophan residue in octamer formation and stability in mitochondrial creatine kinases.

In most organisms, mitochondrial creatine kinase (MtCK) is present as dimers and octamers with the latter predominating under physiological conditions. An absolutely conserved tryptophan residue (Trp-264 in chicken sarcomeric MtCK) appears to play a key role in octamer stability. Recently, it has been shown that the sponge Tethya aurantia, a member of the most ancient group of living multi-cellular animals, expresses an obligate, dimeric MtCK that lacks this absolutely conserved tryptophan residue, instead possessing a tyrosine in this position. In the present study we confirm that the absolutely conserved tryptophan residue is lacking in other sponge MtCKs where it is instead substituted by histidine or asparagine. Site directed mutations of the Trp-264 in expression constructs of chicken sarcomeric MtCK and the octameric MtCK from the marine worm Chaetopterus destabilized the octameric quaternary structure producing only dimers. A Tyr-->Trp mutation in an expression construct of the Tethya MtCK construct failed to produce octamerization; Tyr-->His and Tyr-->Asn mutations also yielded dimers. These results, in conjunction with analysis of homology models of Chaetopterus and Tethya MtCKs, strongly support the view that while the absolutely conserved tryptophan residue is important in octamer stability, octamer formation involves a complex suite of interactions between a variety of residues.

Amino Acid Sequence↗
PubMed2006

The pH dependence of the activity of dehaloperoxidase from Amphitrite ornata.

Dehaloperoxidase (DHP) from the terebellid polychaete, Amphitrite ornata, is the first hemoglobin that has peroxidase activity as part of its native function. The substrate 2,4,6-tribromophenol (TBP) is oxidatively debrominated by DHP to form 2,6-dibromoquinone (DBQ) in a two-electron process. There is a well-defined internal binding site for TBP above the heme, a feature not observed in other hemoglobins or peroxidases. A study of the pH dependence of the activity of DHP reveals a substantial difference in mechanism. From direct observation of the Soret band of the heme it is shown that the pKa for heme activation in protein DHP is 6.5. Below this pH the heme absorbance decreases in the presence of H2O2 with or without addition of substrate. The low pH data are consistent with significant heme degradation. Above pH 6.5 addition of H2O2 causes the heme to shift rapidly to a compound II spectrum and then slowly to an unidentified intermediate with an absorbance of 410 nm. However, the pKa of the substrate TBP is 6.8 and the greatest enzyme activity is observed above the pKa of TBP under conditions where the substrate is a phenolate anion (TPBO-). Although the mechanisms may differ, the data show that both neutral TBP and anionic TPBO- are converted to the quinone product. The mechanistic implications of the pH dependence are discussed by comparison other known peroxidases, which oxidize substrates at the heme edge.

Animals↗
PubMed2004

Cloning and expression of mitochondrial and protoflagellar creatine kinases from a marine sponge: implications for the origin of intracellular energy transport systems.

Creatine kinase (CK) plays a central role in energy transactions in cells displaying high and variable rates of ATP turnover. Cytoplasmic and mitochondrial CK genes code for isoforms which are targeted to distinct intracellular compartments often in close physical proximity to sites of ATP hydrolysis or synthesis. In certain lower groups a third CK gene is present which codes for a flagellar CK isoform consisting of three complete, fused CK domains. Recent work has shown that cytoplasmic, mitochondrial, and flagellar CKs are present in protochordates and in deuterostome and protostome invertebrates. We report here that the marine sponge Tethya aurantia, a representative of the oldest of all multi-cellular animal groups, expresses three unique CK transcripts. One of these CK transcripts codes for protein that has a mitochondrial targeting sequence and in a phylogenetic analysis is positioned at the base of the cluster containing mitochondrial CK sequences from invertebrates, protochordates, and vertebrates; it is clearly a mitochondrial CK. When expressed in Escherichia coli the mitochondrial form from T. aurantia was found to be dimeric unlike all other mitochondrial CKs which are typically octameric. The other two T. aurantia transcripts code for proteins that appear to be more closely related to flagellar CKs. These protoflagellar CKs were found to be dimers when expressed in Escherichia coli. Sponges last shared a common ancestor with higher animals as long as one billion years ago. The antiquity of intracellular localization, as evidenced by the presence of a true mitochondrial CK and protoflagellar CKs in the sponge T. aurantia, indicates that physical constraints on cellular energy transport were key, early driving forces in the evolution of this key enzyme system.

Amino Acid Sequence↗
PubMed2004

Amphitrite ornata dehaloperoxidase: enhanced activity for the catalytically active globin using MCPBA.

Dehaloperoxidase (DHP) from Amphitrite ornata is the only heme-containing, hydrogen peroxide-dependent globin capable of oxidatively dehalogenating halophenols to yield the corresponding quinones. To ascertain that this enzymatic activity is intrinsic to DHP, we have cloned and expressed the enzyme in Escherichia coli. We also find that an alternate oxygen atom donor, meta-chloroperbenzoic acid, gives appreciably higher activity than hydrogen peroxide. Under optimal turnover conditions (large peroxide/peracid excess), after an initial burst of activity, DHP appears to become trapped in a non-catalytic state (possibly Compound II) and is unable to fully convert all halophenol to product. However, full substrate conversion can be achieved under more physiological conditions involving a much smaller excess of oxygen atom donor. Parallel studies have been carried out using horseradish peroxidase and myoglobin to calibrate the activity of DHP versus typical peroxidase and globin proteins, respectively.

Animals↗
PubMed2004

Identification and expression of two novel cytochrome P450 genes, belonging to CYP4 and a new CYP331 family, in the polychaete Capitella capitata sp.I.

The polychaete Capitella capitata sp.I has a high capacity to metabolize polycyclic aromatic hydrocarbons (PAHs) which are among the most hazardous environmental pollutants with significant biological effects. In the present study, two novel cytochrome P450 (CYP) genes were identified in this species. One was named CYP331A1, the first member of a new family of CYP331, and the other CYP4AT1 is the first member of a new subfamily CYP4AT. Both of these genes are constitutively expressed in the worms and detectable by RT-PCR. The expression of CYP331A1 mRNA was observed to be more sensitive to PAH exposure than CYP4AT1, which indicated that CYP331A1 should play a more important role than CYP4AT1 in PAH metabolism in this species. Considering the importance of C. capitata sp.I in taking up PAH and other organic pollutants from contaminated marine sediments with the potential for subsequent food-chain transfer, our results are important for understanding the molecular basis of biotransformation and detoxification in this invertebrate, and also have evolutionary significance for understanding the diversity and history of the CYP superfamily.

Amino Acid Sequence↗
PubMed2005

Characterisation of two novel CYP4 genes from the marine polychaete Nereis virens and their involvement in pyrene hydroxylase activity.

Cytochrome P450 enzymes (CYP enzymes) catalyse the initial step in biotransformation of xenobiotics like polycyclic aromatic hydrocarbons (PAHs). The marine polychaete Nereis virens has a high capacity for biotransformation of PAHs. In the present study, the complete cDNA sequences of two novel CYP genes isolated from N. virens gut tissue are reported. One named CYP342A1, the first member of a new family and the other named CYP4BB1, the first member of a new subfamily. This is the first investigation of specific CYP enzymes from marine polychaetes in which catalytic activity has been determined. Both CYP enzymes had monooxygenase activity and catalysed hydroxylation of pyrene to 1-hydroxypyrene. Based on the present results it is likely that both CYP4BB1 and CYP342A1 are involved in xenobiotic biotransformation. Furthermore, site-directed mutagenesis of the conserved cysteine residue of the heme binding domain resulted in complete loss of monooxygenase activity of both CYP enzymes, indicating that this cysteine residue is indispensable for monooxygenase activity of invertebrate CYP enzymes, as has been well documented in vertebrates. Considering the important role of CYP enzymes in biotransformation of xenobiotics and the presence of N. virens in estuarine environments that accumulates organic xenobiotics, our results are important in understanding the molecular mechanism of biotransformation in marine polychaetes.

Amino Acid Sequence↗
PubMed2006

A novel fibrinolytic serine protease from the polychaete Nereis (Neanthes) virens (Sars): purification and characterization.

A novel fibrinolytic serine protease has been identified and purified to homogeneity from the coelomic fluid of polychaete Nereis (Neanthes) virens (Sars), and named N-V protease. N-V protease is a 29kDa single chain protein with an isoelectric point of pH 4.5. It hydrolyzes Aalpha-chain of fibrinogen with a high efficiency, and the Bbeta- and gamma-chains (Aalpha>Bbeta>gamma) with a lower efficiency. The proteolytic activity peaks at pH 7.8 is 45 degrees C. The activity is completely inhibited by serine protease inhibitors DFP (I(50)=5.8 x 10(-4)M) and PMSF (I(50)=5.5 x 10(-2)M), and almost completely by TLCK (I(50)=7.7 x 10(-1) M). But aprotinin, elastinal, SBTI, benzamidine, PCMB, EDTA, EGTA, iodoacetate, E64, and beta-mercaptoethanol have no effect on the protease activity. Therefore, N-V protease is identified as a serine protease. The primary amino acid sequence of N-V protease was determined by mass spectrometry (N-V protease, No. P83433). According to the MALDI-TOF MS analysis, there is no existing protein in the NCBI Non-redundant Protein Sequence Database that matches the N-V protease sequence. Therefore, N-V protease is a novel and special protein in N. virens. Furthermore, we have successfully established an expression cDNA library from the whole body of N. virens (data not shown).

Amino Acid Sequence↗
PubMed2005

A discoidal lipoprotein from the coelomic fluid of the polychaete Nereis virens.

A discoidal lipoprotein was isolated from the coelomic fluid of the polychaete, Nereis virens, by density gradient centrifugation. The lipoprotein was present in both sexes and moved as a uniform band in an agarose gel. The average diameter of the lipoprotein particles determined by electron microscopy was 42 nm with a thickness of 10 nm. SDS electrophoresis showed two apoprotein subunits with molecular masses of 247 and 85 kDa, respectively. In lectin blots, both apoproteins were reactive with Concanavalin A indicating the presence of N-glycans. The small subunit was also reactive with peanut lectin, indicating additional O-glycosylation. The total lipid content was 48% and consisted mainly of phospholipids and some diglycerides as judged by thin layer chromatography. The estimated native molecular mass of N. virens lipoprotein ( approximately 675 kDa) lies in the range of vertebrate high-density lipoprotein and insect lipophorins. The size of the apoproteins is similar to those found in insects, while the composition of the lipid fraction is more similar to that of crustacean lipoproteins.

Animals↗
PubMed2006

The multigenic family of the extracellular hemoglobin from the annelid polychaete Arenicola marina.

The extracellular hemoglobin of the lugworm Arenicola marina which inhabits on the intertidal area, a sulfide-rich environment, comprises eight globin chains previously determined by mass spectrometry. We have cloned and sequenced five of the globin components. The deduced amino-acid sequences exhibit an extracellular signal peptide and two cysteine residues involved in an internal disulfide bond. The molecular weights calculated from the globin primary structures obtained from complete cDNA sequences are in good agreement with the mass spectrometry values obtained with the native hemoglobin. Phylogenetic analysis has allowed assigning the five A. marina sequences to the different globin sub-families. Two of the globins were found to be A2 globin chains lacking the cysteine residues proposed to be involved in the binding of hydrogen sulfide by such hemoglobin. We discuss the unusual absence of these cysteines in the light of their invariant occurrence in the A2 subfamily of hemoglobins from annelids inhabiting sulfide-rich environments.

Amino Acid Sequence↗
PubMed2005

Isolation, characterization, and cDNA-derived amino acid sequence of glycocyamine kinase from the tropical marine worm Namalycastis sp.

We isolated cytoplasmic glycocyamine kinase (GK) and creatine kinase (CK) from the tropical marine worm Namalycastis sp. by ammonium sulfate fractionation, gel filtration on Sephacryl S-200, and DEAE-5PW chromatography. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) showed that the isolated GK is highly purified and appears to be a heterodimer of two distinct subunits, alpha and beta, with molecular masses of approximately 40 kDa. The complete nucleotide sequences of the cDNAs for Namalycastis GKalpha and GKbeta were 1527 (encoding 374 amino acids) and 1579 bp (encoding 390 amino acids), respectively. The predicted amino acid sequences differ only in the N-terminal 50 residues. This is consistent with the characteristics of Neanthes GKalpha and GKbeta chains, which we have previously shown to be generated by alternative splicing. The recombinant enzymes GKalpha, GKbeta, and CK from Namalycastis were successfully expressed in Escherichia coli as maltose-binding protein fusion proteins. In contrast to the stable GKbeta enzyme, GKalpha was quite unstable, and its activity decreased remarkably with time. Thus, the N-terminal 50 residues appear to play a key role in enzyme stability. The kinetic parameters for the native GK heterodimer were similar to GKbeta, suggesting that GKalpha would have an activity similar to GKbeta if part of a heterodimer. This is the first report of precise kinetic parameters for GK. Finally, based on our results, we present a model for pluriphosphagen function in Namalycastis wherein cytoplasmic GK and CK and mitochondrial CK function together with phosphocreatine and phosphoglycocyamine to enable cells to respond quickly to a sudden large energy requirement.

Amino Acid Sequence↗
PubMed2005

Characterization of lipovitellin in eggs of the polychaete Neanthes arenaceodentata.

The ooplasm of mature oocytes of the polychaete Neanthes arenaceodentata is characteristically filled with yolk platelets. A major component of these structures is lipovitellin, which provides energy and materials required by newly hatched larvae. The lipovitellin isolated and purified from the fertilized eggs of this polychaete was a high-density lipoprotein composed of protein (57%), lipid (42%) and carbohydrate (1%). The lipid component included phospholipids (92% of lipid), triacylglycerol (3% of lipid) and cholesterol (3% of lipid), while sodium dodecyl sulfate-gel electrophoresis showed the major protein component was a 120-kDa peptide. Microscopically, mature oocytes were present in the coelom along with phagocytic eleocytes. The presence of muscle fragments and oil droplets in eleocytes suggests that eleocytes play an important role in providing the protein and lipid needed for the assembly of lipovitellin in the oocytes.

Animals↗
PubMed2005

The amino acid sequence of tauropine dehydrogenase from the polychaete Arabella iricolor.

The amino acid sequence of tauropine dehydrogenase (EC 1.5.1.23) from the polychaete Arabella iricolor was determined by automated sequencing of fragments obtained by cleavage with lysyl endopeptidase, endoproteinase Glu-C, and cyanogen bromide. The purified enzyme contained two isoforms that differ only in the 41st amino acid residue (Thr or Ile). Although the sequence contained eight Cys residues, intrachain disulfide bonds were not found. Two possible N-linked glycosylation sites occur in the sequences, but the enzyme does not appear to contain bound carbohydrates. Based on these data, the two isoforms of Arabella tauropine dehydrogenase are simple proteins consisted of 396 amino acid residues with calculated molecular masses of 43,085.7 Da (Thr41 isoform) and 43,097.8 Da (Ile41 isoform).

Amino Acid Oxidoreductases↗
PubMed2005

Lipid composition of deep-sea hydrothermal vent tubeworm Riftia pachyptila, crabs Munidopsis subsquamosa and Bythograea thermydron, mussels Bathymodiolus sp. and limpets Lepetodrilus spp.

Lipid composition was determined for hydrothermal vent species collected by the Deep Submergence Vehicle ALVIN from chimneys at 2,500 m depth on the East Pacific Rise. These are the first lipid biomarker studies for most of these species. Lipid content was low and dominated by polar lipid in the vestimentiferan tubeworm Riftia pachyptila, mussels Bathymodiolus sp. and limpets Lepetodrilus spp. The galatheid (Munidopsis subsquamosa) and most brachyuran adult (Bythograea thermydron) crabs were characterized by higher storage lipid (triacylglycerol). Total polyunsaturated fatty acids were similar in R. pachyptila plume and body, but higher in the posterior part of the soft body, which had more docosahexaenoic acid (2-5% of total FA) compared to the anterior and plume (< or =0.3%). Two sulphur-oxidizing bacterial markers, 16:1(n-7)c and 18:1(n-7)c, were high in R. pachyptila and mussel (up to 23%), but lower in both crab species (4-17%). R. pachyptila had greater nonmethylene interrupted diunsaturated fatty acids (8-13%) than all other species (2-8%). R. pachyptila may desaturate and elongate 18:1(n-7)c to obtain essential polyunsaturated fatty acids 20:5(n-3) and 20:4(n-6). The sterol composition of R. pachyptila included similar amounts of cholesterol and desmosterol, whereas the other species had a more diverse sterol composition. These differences in lipids, fatty acids and sterols reflect diverse nutritional strategies and possibly temperature regimes in these species.

Adaptation, Physiological↗