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Assaf Sukenik - One of the best experts on this subject based on the ideXlab platform.
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CHARACTERIZATION OF A GENE ENCODING THE LIGHT-HARVESTING VIOLAXANTHIN-CHLOROPHYLL PROTEIN OF NANNOCHLOROPSIS SP. (EUSTIGMATOPHYCEAE)
Journal of phycology, 2000Co-Authors: Assaf Sukenik, Alexander Livne, Kirk E. Apt, Arthur R. GrossmanAbstract:In contrast to vascular plants, green algae, and diatoms, the major light-harvesting complex of the marine Eustigmatophyte genus Nannochloropsis is a violaxanthin-chlorophyll a protein complex that lacks chlorophylls b and c. The isolation of a single polypeptide from the light-harvesting complex of Nannochloropsis sp. (IOLR strain) was previously reported (Sukenik et al. 1992). The NH2 -terminal amino acid sequence of this polypeptide was significantly similar to NH2 -terminal sequences of the light-harvesting fucoxanthin, chlorophyll a/c polypeptides from the diatom Phaeodactylum tricornutum Bohlin. Using polyclonal antibodies raised to the Nannochloropsis light-harvesting polypeptide, a gene encoding this polypeptide was isolated from a cDNA expression library. The deduced amino acid sequence of the Nannochloropsis violaxanthin-chlorophyll a polypeptide reveals a 36 amino acid presequence followed by 173 amino acids that constitute the mature polypeptide. The mature polypeptide has 30%-40% sequence identity to the diatom fucoxanthin-chlorophyll a/c polypeptides and less then 27% identity to the green algal and vascular plant light-harvesting chlorophyll polypeptides that bind both chlorophylls a and b. Its molecular mass, as deduced from the gene sequence, is 18.4 kDa with three putative transmembrane helices and several residues that may be involved in chlorophyll binding. The cDNA encoding the violaxanthin-chlorophyll a polypeptide was used to isolate and characterize a 10 kb genomic fragment containing the entire gene. The open reading frame was interrupted by five introns ranging in size from 123 to 449 bp. The intron borders have typical eukaryotic GT … AG sequences.
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uptake efflux and photosynthetic utilization of inorganic carbon by the marine Eustigmatophyte nannochloropsis sp 1
Journal of Phycology, 1997Co-Authors: Assaf Sukenik, Dan Tchernov, Aaron Kaplan, Emma Huertas, Luis M Lubian, Alexander LivneAbstract:Uptake, efflux and utilization of inorganic carbon were investigated in the marine Eustigmatophyte Nannochloropsis sp. grown under an air level of CO2. Maximal photosynthetic rate was hardly affected by raising the pH porn 5.0 to 9.0. The apparent photosynthetic affinity for dissolved inorganic carbon (DIC) was 35 μM DIC between pH 6.5 to 9.0, but increased approximately threefold at pH 5.0 suggesting that HCO3- was the main DIC species used from the medium. No external carbonic anhydrase (CA) activity could be detected by the pH drift method. However, application of ethoxyzolamide (an inhibitor of CA) resulted an a significant inhibition of photosynthetic O2 evolution and carbon utilization, suggesting involvement of internal CA or CA-like activity in DIC utilization. Under high light conditions, the rate of HCO3− uptake and its internal conversion to CO2 apparently exceeded the rate of carbon fixation, resulting in a large leak of CO2 from the cells to the external medium. When the cells were exposed to low DIC concentrations, the ratio of internal to external DIC concentration was about eight. On the other hand, in the presence of 2 mM DIC, conditions prevailing in the marine environment, the internal concentration of DIC was only 50% higher than the external one.
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potential advantages of frozen algae nannochloropsis sp for rotifer brachionus plicatilis culture
Aquaculture, 1995Co-Authors: Esther Lubzens, Odi Zmora, O Gibson, Assaf SukenikAbstract:Abstract The Eustigmatophyte Nannochloropsis is widely used in many aquaculture hatcheries to establish the initial step of an artificial food chain. The advantage of Nannochloropsis over other unicellular algae is primarily its unique fatty acid composition. Rotifers which consume the algae carry these fatty acids to the fish larvae. Cultivation of large quantities of algal biomass to support this food chain is a heavy burden in many hatcheries, and in many other locations it cannot be carried out all year round. In this study we examined the possibility of substituting frozen biomass for fresh Nannochloropsis as a sole food source for rotifer cultures or as an enrichment treatment prior to feeding the rotifers to the larvae. Relatively high reproductive rates were found in rotifers of three strains which were fed frozen Nannochloropsis biomass. Total fatty acid content of these rotifers and fatty acid distribution were related to the chemical composition of the algae. Although seasonal variations in biochemical composition and fatty acid distribution were found in the algal biomass, the quality of the long-term frozen algae was adequate to provide the rotifers with the essential fatty acids almost all year round. No differences were found in the fatty acid composition of rotifers fed with algae stored at − 20 °C or − 70 °C. The thawed algal biomass could be kept at 4 °C for 7 days and be used for rotifer feeding without a significant adverse effect on the fatty acid content and composition in the rotifers. The results of this study suggest that application of frozen Nannochloropsis biomass may promote easier management in biomass production of lipid-enriched rotifers. This provides the artificial food chain with essential fatty acids, which are crucial for the development and cultivation of fish larvae, with a relatively limited effort for algae production on the hatchery site.
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biochemical quality of marine unicellular algae with special emphasis on lipid composition ii nannochloropsis sp
Aquaculture, 1993Co-Authors: Assaf Sukenik, Odi Zmora, Yael CarmeliAbstract:Abstract The Eustigmatophyte, Nannochloropsis sp., contains relatively large amounts of valuable lipids and is commonly grown as food source for commercial application in aquaculture. In this study we evaluated the effect of environmental conditions such as light intensity, nitrogen availability and temperature on cellular chemical composition with special emphasis on fatty acid distribution in cultures of Nannochloropsis sp. continuously grown under laboratory-controlled conditions. Seasonal variations in cellular chemistry were further assessed using large-scale outdoor shallow ponds, aimed at mass production of Nannochloropsis for application in an aquaculture hatchery. The percentage of the polyunsaturated long-chain fatty acid, eicosapentaenoic acid, in the algal biomass varied between 1.6 and 3.8% (w/w). In spite of significant variations in cellular protein content, the amino acid composition of Nannochloropsis biomass remained fairly constant during the different production seasons. Variations in the fatty acid composition of the algal biomass are attributed to differences in seasonal climatic conditions and diurnal cycles in light intensity and temperature. This study demonstrates the feasibility of culturing algal biomass of a high chemical quality for various applications in aquaculture hatcheries.
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alterations in lipid molecular species of the marine Eustigmatophyte nannochloropsis sp
Journal of Phycology, 1993Co-Authors: Assaf Sukenik, Yuji Yamaguchi, Alexander LivneAbstract:The molecular species of triacylglycerol and monogalactosyl diacylglycerol from the marine Eustigmatophyte Nannochloropsis were analyzed by high-performance liquid chromatography with a flame ionization detector. Four major molecular species of triacylglycerol composed of C 14:0, C 16:0, and C 16:1 fatty acids at different combinations were identified. Six molecular species of monogalactosyl diacylglycerol were detected. Three of them contained C 20:5 fatty acid in the sn-1 position, and one component accommodated C 20:5 fatty acid in both the sn-1 and sn-2 positions. Variations in the relative distribution of the molecular species were further monitored in Nannochloropsis cultures grown under different irradiance levels and temperatures. The relative distribution of 16: 0/16:1/16:0 triacylglycerol increased in cells grown in high light and in high temperature. Variations in cellular fatty acid composition in Nannochloropsis grown under different environmental conditions of irradiance level and temperature were attributed to alterations in relative cellular content of lipid classes as well as in the relative composition of lipid class molecular species.
Alexander Livne - One of the best experts on this subject based on the ideXlab platform.
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CHARACTERIZATION OF A GENE ENCODING THE LIGHT-HARVESTING VIOLAXANTHIN-CHLOROPHYLL PROTEIN OF NANNOCHLOROPSIS SP. (EUSTIGMATOPHYCEAE)
Journal of phycology, 2000Co-Authors: Assaf Sukenik, Alexander Livne, Kirk E. Apt, Arthur R. GrossmanAbstract:In contrast to vascular plants, green algae, and diatoms, the major light-harvesting complex of the marine Eustigmatophyte genus Nannochloropsis is a violaxanthin-chlorophyll a protein complex that lacks chlorophylls b and c. The isolation of a single polypeptide from the light-harvesting complex of Nannochloropsis sp. (IOLR strain) was previously reported (Sukenik et al. 1992). The NH2 -terminal amino acid sequence of this polypeptide was significantly similar to NH2 -terminal sequences of the light-harvesting fucoxanthin, chlorophyll a/c polypeptides from the diatom Phaeodactylum tricornutum Bohlin. Using polyclonal antibodies raised to the Nannochloropsis light-harvesting polypeptide, a gene encoding this polypeptide was isolated from a cDNA expression library. The deduced amino acid sequence of the Nannochloropsis violaxanthin-chlorophyll a polypeptide reveals a 36 amino acid presequence followed by 173 amino acids that constitute the mature polypeptide. The mature polypeptide has 30%-40% sequence identity to the diatom fucoxanthin-chlorophyll a/c polypeptides and less then 27% identity to the green algal and vascular plant light-harvesting chlorophyll polypeptides that bind both chlorophylls a and b. Its molecular mass, as deduced from the gene sequence, is 18.4 kDa with three putative transmembrane helices and several residues that may be involved in chlorophyll binding. The cDNA encoding the violaxanthin-chlorophyll a polypeptide was used to isolate and characterize a 10 kb genomic fragment containing the entire gene. The open reading frame was interrupted by five introns ranging in size from 123 to 449 bp. The intron borders have typical eukaryotic GT … AG sequences.
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uptake efflux and photosynthetic utilization of inorganic carbon by the marine Eustigmatophyte nannochloropsis sp 1
Journal of Phycology, 1997Co-Authors: Assaf Sukenik, Dan Tchernov, Aaron Kaplan, Emma Huertas, Luis M Lubian, Alexander LivneAbstract:Uptake, efflux and utilization of inorganic carbon were investigated in the marine Eustigmatophyte Nannochloropsis sp. grown under an air level of CO2. Maximal photosynthetic rate was hardly affected by raising the pH porn 5.0 to 9.0. The apparent photosynthetic affinity for dissolved inorganic carbon (DIC) was 35 μM DIC between pH 6.5 to 9.0, but increased approximately threefold at pH 5.0 suggesting that HCO3- was the main DIC species used from the medium. No external carbonic anhydrase (CA) activity could be detected by the pH drift method. However, application of ethoxyzolamide (an inhibitor of CA) resulted an a significant inhibition of photosynthetic O2 evolution and carbon utilization, suggesting involvement of internal CA or CA-like activity in DIC utilization. Under high light conditions, the rate of HCO3− uptake and its internal conversion to CO2 apparently exceeded the rate of carbon fixation, resulting in a large leak of CO2 from the cells to the external medium. When the cells were exposed to low DIC concentrations, the ratio of internal to external DIC concentration was about eight. On the other hand, in the presence of 2 mM DIC, conditions prevailing in the marine environment, the internal concentration of DIC was only 50% higher than the external one.
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alterations in lipid molecular species of the marine Eustigmatophyte nannochloropsis sp
Journal of Phycology, 1993Co-Authors: Assaf Sukenik, Yuji Yamaguchi, Alexander LivneAbstract:The molecular species of triacylglycerol and monogalactosyl diacylglycerol from the marine Eustigmatophyte Nannochloropsis were analyzed by high-performance liquid chromatography with a flame ionization detector. Four major molecular species of triacylglycerol composed of C 14:0, C 16:0, and C 16:1 fatty acids at different combinations were identified. Six molecular species of monogalactosyl diacylglycerol were detected. Three of them contained C 20:5 fatty acid in the sn-1 position, and one component accommodated C 20:5 fatty acid in both the sn-1 and sn-2 positions. Variations in the relative distribution of the molecular species were further monitored in Nannochloropsis cultures grown under different irradiance levels and temperatures. The relative distribution of 16: 0/16:1/16:0 triacylglycerol increased in cells grown in high light and in high temperature. Variations in cellular fatty acid composition in Nannochloropsis grown under different environmental conditions of irradiance level and temperature were attributed to alterations in relative cellular content of lipid classes as well as in the relative composition of lipid class molecular species.
John K Volkman - One of the best experts on this subject based on the ideXlab platform.
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algaenan structure in the microalga nannochloropsis oculata characterized from stepwise pyrolysis
Organic Geochemistry, 2017Co-Authors: Zhirong Zhang, John K VolkmanAbstract:Abstract Dried biomass of the Eustigmatophyte Nannochloropsis oculata was subjected to stepwise pyrolysis at 50 °C intervals from 310 to 610 °C to test the potential of the technique for investigating the algaenan structure of N. oculata and for determining a broad suite of biochemical constituents. Pyrolysis at 310 °C yielded mainly free lipids such as phytol, cholesterol, C 32 alkyl diols, hexadecanamide and large amounts of phytol-derived alkenes from thermal desorption. Indole generated from protein degradation first appeared at 360 °C, indicating the onset of biopolymer breakdown. The pyrolyzate of 410 °C showed a simpler composition, dominated by 2-methyl-1H-indole and indole, and accompanied by low amounts of phenol and hexadecanamide. At 460 °C, algaenan breakdown was evident from the detection of C 15 –C 19 n -alkan-2-ones with a strong predominance of C 17 , and of C 29 –C 33 mid-chain ketones composed of a remarkable predominance of the symmetrical ketone C 31 n -alkan-16-one. Small amounts of the mono-unsaturated C 31:1 mid-chain ketone and n -alkene/ n -alkane doublets were also present. The chromatograms suggest that the algaenan structure of N. oculata is composed of repeating, interlinked C 32 n -alkan-1,17-diols, whereas the free plus bound lipids were dominated by the C 32 n -alkan-1,15-diol. The pyrolyzate at 510 °C was dominated by a bimodal distribution of C 8 –C 32 n -alkene/ n -alkane doublets showing a maximum at n -C 14:1 and n -C 26 , with lesser amounts of ketones. Such a wide chain length distribution implies that other aliphatic lipids, perhaps derived from the long chain n -alkenols, might also be involved in the algaenan structure. Major constituents of the 560 °C pyrolyzate were aromatic compounds, including toluene, phenol and indole, but absolute abundances were low. It is notable that high molecular weight compounds such as the n -alkene/ n -alkane doublets were no longer detected at 560 °C. The results show that stepwise pyrolysis provides simpler chromatograms than a single pyrolysis of a whole sample at 610 °C and so can be a useful tool for identifying algaenan structures and/or related compounds in ancient sediments and modern microalgae.
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Eustigmatophyte microalgae are potential sources of c29 sterols c22 c28 n alcohols and c28 c32 n alkyl diols in freshwater environments
Organic Geochemistry, 1999Co-Authors: John K Volkman, Stephanie M Barrett, Susan I BlackburnAbstract:The neutral lipids of three freshwater microalgae from the class Eustigmatophyceae were examined to investigate possible algal sources of lipids in lacustrine sediments. The major neutral lipids in Eustigmatos vischeri (Hulbert) Taylor, Vischeria helvetica (Vischer et Pascher) Taylor and Vischeria punctata Vischer were sterols, long-chain alcohols and alkyl diols. The distributions of long-chain n-alkanols and n-alkenols were very similar in each species, but there were small interspecies differences in the proportions of alkyl diols. Saturated alcohols ranged from 14:0 to 28:0 (both present in trace amounts), with 22:0 as the major alkanol. The latter has previously been reported to be the major n-alcohol in some lacustrine sediments. C16–C30 monounsaturated alcohols were more abundant: 26:1 and 28:1 were the major constituents. The sterol distributions consisted predominantly of 24-ethylcholesterol with small amounts of cholesterol, 24-methylcholesterol, 24-ethylcholesta-5,22E-dien-3β-ol and isofucosterol. These results add to the growing list of microalgae that contain a high proportion of 24-ethylcholesterol, which is more typically associated with higher plants. The long-chain alkyl diols ranged from C28 to C32: the major constituents were the C28 1,13-diol and C30 and C32 1,15 diols which occurred together with smaller amounts of other positional isomers. C30 and C32 alkyl diols have been found in marine Eustigmatophytes of the genus Nannochloropsis, and these new results confirm that the same class of compounds occurs in freshwater Eustigmatophytes.
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nutritional properties of microalgae for mariculture
Aquaculture, 1997Co-Authors: Malcolm R Brown, John K Volkman, S W Jeffrey, Graeme A DunstanAbstract:Microalgae are used in mariculture as live feeds for all growth stages of molluscs, for the larval stages of crustaceans and some fish species, and for zooplankton used in mariculture food chains. In order to be nutritionally sufficient, microalgae must supply a balanced mixture of nutrients. We have studied the biochemical composition of about 40 species of microalgae from seven algal classes to define those that may be best adapted to the Australian conditions. Microalgae varied in their proportions of protein (6652%), carbohydrate (5523%) and lipid (7-23%). All species had similar amino acid composition, and were rich in the essential amino acids. Microalgal polysaccharides were variable in sugar composition, but most had high proportions of glucose (21~87%). Diatoms, prymnesiophytes, cryptomonads and Eustigmatophytes were rich in one or both of the 20:5( n - 3) and 22:6( n - 3) polyunsaturated fatty acids important for marine fish larvae (5-35% total fatty acids), prasinophytes had low to moderate levels of one of the acids (4-10%) whereas chlorophytes were deficient in both acids (O-3%). All species had relatively high concentrations of ascorbic acid (l-16 mg g- ’ dry weight) and riboflavin (20-40 kg g-l). The likely nutritional values of the microalgae, based on their biochemical composition, are discussed. 0 1997 Elsevier Science B.V.
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c30c32 alkyl diols and unsaturated alcohols in microalgae of the class eustigmatophyceae
Organic Geochemistry, 1992Co-Authors: John K Volkman, Graeme A Dunstan, Stephanie M Barrett, S W JeffreyAbstract:A study of the neutral lipids of the marine microalgae Nannochloropsis oculata Droop (2 strains), Nannochloropsis salina Hibberd and an unnamed species, all from the little-studied yellow-green algal class Eustigmatophyceae (Chromophyta), has shown that these microalgae contain unusual C30C32 1,15-alkyl diols and a monounsaturated C32 1,15-diol. Alkane diols are abundant in many marine sediments, but this is the first report of their occurrence in cultured microalgae. This results argues against the suggestion, based on the identification of the same diols in a natural bloom of the cyanobacterium Aphanizomenon flos-aquae from the Baltic Sea, that these compounds are specific cyanobacterial markers. C32 homologues were more abundant than C30 homologues in the Eustigmatophytes, as in the field sample of A. flos-aquae, whereas in most sediments the reverse is found. This suggests that the biological origin for these compounds in sedements may well be microalgae other than those studied here. The diols do not occur as free lipids in the Eustigmatophytes, at least under the culture conditions used, but they could be liberated from more polar lipids by acid hydrolysis. In contrast, the major form of the alkyl diols in sediments appears to be as free lipids and not esters. Acid hydrolysis also liberated C30C32 mono and diunsaturated straight-chain alcohols. The carbon number distributions of the alcohols and diols are identical, and the relative proportions of homologues are similar, suggesting that both compound classes are formed by the same biosynthetic pathway. The sterol compositions are also unusual with cholesterol comprising about 75% of the total sterols. C28 sterols were not detected, but small amounts of the C29 sterols 24-ethylcholesta-5,24 (28)E-dien-3β-ol and 24-ethylcholesta-5,24(28)Z-dien-3β-ol were found in all algae. N. salina also contained 24-ethylcholesterol.
Sandhya Mishra - One of the best experts on this subject based on the ideXlab platform.
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a comparative analysis of different extraction solvent systems on the extractability of eicosapentaenoic acid from the marine Eustigmatophyte nannochloropsis oceanica
Algal Research-Biomass Biofuels and Bioproducts, 2019Co-Authors: Madhusree Mitra, Sandhya MishraAbstract:Abstract Omega-3 fatty acid rich microalgal oil is currently gaining attention as a sustainable and promising alternative to other sources. This work aims to evaluate the recovery of eicosapentaenoic acid (EPA, C20:5n3) from Nannochloropsis oceanica by means of six different solvent systems including a classic system such as chloroform:methanol along with four other non-toxic mixes. The total lipids and lipid classes are also assessed along with the fatty acid profiles. Despite the high lipid content in chloroform:methanol (1:2); hexane:methanol (3:2) and dichloromethane:methanol (2:1), solvent systems result in higher amounts of EPA recovery, thus making them a suitable choice for extracting EPA compared to toxic solvents such as chloroform. However, an extensive comparative analysis was needed to validate the extraction efficacy of these solvent systems for scaling-up the process. Furthermore, the pigment profile of N. oceanica extracted using different extracts is also evaluated in this study.
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effect of glucose on growth and fatty acid composition of an euryhaline Eustigmatophyte nannochloropsis oceanica under mixotrophic culture condition
Bioresource Technology Reports, 2018Co-Authors: Madhusree Mitra, Sandhya MishraAbstract:Abstract We aspire to evaluate the effect of glucose as a carbon source on growth, total lipid yield, polyunsaturated fatty acid and (mainly eicosapentaenoic acid) accumulation of N. oceanica. Microalgal cells were cultured in medium supplemented with different concentrations of glucose (0–40 g L−1), and its effect on growth, cellular components including fatty acid compositions was analyzed. We found that even though, N. oceanica displayed a lower growth trend under stress conditions than that of control howbeit showed a marked increase in the cellular lipid contents. The protein and carbohydrate content also get influenced by the glucose stress and because of carbon partitioning. These results could be used to tailor the culture conditions to ameliorate the content of the product of interest. Maximum lipid and eicosapentaenoic acid content were observed at 25 g L−1, while 30 and 40 g L−1 seems to be ideal for attaining higher carbohydrate and protein.
Malcolm R Walter - One of the best experts on this subject based on the ideXlab platform.
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combined micro fourier transform infrared ftir spectroscopy and micro raman spectroscopy of proterozoic acritarchs a new approach to palaeobiology
Precambrian Research, 2005Co-Authors: Craig P Marshall, Emmanuelle Javaux, Andrew H Knoll, Malcolm R WalterAbstract:Abstract Micro-scale analytical techniques permit correlation of chemistry with morphology of individual Proterozoic acritarchs (organic-walled microfossils), and thus provide new approaches for elucidating their biological affinities. A combination of micro-Fourier transform infrared (FTIR) spectroscopy and laser micro-Raman spectroscopy was used to investigate the organic structure and composition of individual acritarchs. Well preserved Neoproterozoic acritarchs from the Tanana Formation, Australia (ca. 590–565 Ma), and Mesoproterozoic acritarchs from the Roper Group (1.5–1.4 Ga), Australia, and Ruyang Group, China (1.4–1.3 Ga, age poorly resolved but certainly >1000 Ma and H stretching bands in the 2900 cm−1 region relative to the C C aromatic ring stretching band at 1600 cm−1. This FTIR spectrum is consistent with the FTIR spectra obtained from algaenans isolated from extant chlorophyte and Eustigmatophyte microalgae. FTIR spectra of Leiosphaeridia sp. from the Tanana Formation contain a less intense aliphatic C H stretching band relative to the C C aromatic ring stretching band. By comparison, the spectra acquired from the Mesoproterozoic acritarchs were dominated by C C aromatic ring stretching bands at 1600 cm−1 relative to moderate-weak CH3 terminal groups (1345 cm−1), C H aliphatic stretching (3000–2700 cm−1), and C O (1710 cm−1), although some differences in biopolymer composition occurred between species. Curve-fitting of the aliphatic C Hx stretching region provides greater insight into the aliphatic structures of the acritarchs. The CH2/CH3 intensity ratio can be used to assess the relative chain length and degree of branching. Organic material in the Tanarium conoideum consists of straight long chain hydrocarbons, while the other acritarchs contain hydrocarbons consisting of short chains that are highly branched. In this study it was found that Raman spectroscopy does not provide additional information about biopolymer composition of Proterozoic acritarchs, but rather offers complementary data regarding the aromaticity and degree of saturation of the macromolecular structure of acritarch cysts.
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Combined micro-Fourier transform infrared (FTIR) spectroscopy and micro-Raman spectroscopy of Proterozoic acritarchs: A new approach to Paleobiology
2005Co-Authors: Craig P Marshall, Emmanuelle Javaux, Andrew H Knoll, Malcolm R WalterAbstract:Abstract Micro-scale analytical techniques permit correlation of chemistry with morphology of individual Proterozoic acritarchs (organic-walled microfossils), and thus provide new approaches for elucidating their biological affinities. A combination of micro-Fourier transform infrared (FTIR) spectroscopy and laser micro-Raman spectroscopy was used to investigate the organic structure and composition of individual acritarchs. Well preserved Neoproterozoic acritarchs from the Tanana Formation, Australia (ca. 590-565 Ma), and Mesoproterozoic acritarchs from the Roper Group (1.5-1.4 Ga), Australia, and Ruyang Group, China (1.4-1.3 Ga, age poorly resolved but certainly >1000 Ma and <1625 Ma) have thermal maturities that range from immature to oil window. FTIR spectra of Tanarium conoideum from the Tanana Formation contain intense aliphatic C H stretching bands in the 2900 cm −1 region relative to the C C aromatic ring stretching band at 1600 cm −1 . This FTIR spectrum is consistent with the FTIR spectra obtained from algaenans isolated from extant chlorophyte and Eustigmatophyte microalgae. FTIR spectra of Leiosphaeridia sp. from the Tanana Formation contain a less intense aliphatic C H stretching band relative to the C C aromatic ring stretching band. By comparison, the spectra acquired from the Mesoproterozoic acritarchs were dominated by C C aromatic ring stretching bands at 1600 cm −1 relative to moderate-weak CH 3 terminal groups (1345 cm −1 ), C H aliphatic stretching (3000-2700 cm −1 ), and C O (1710 cm −1 ), although some differences in biopolymer composition occurred between species. Curve-fitting of the aliphatic C H x stretching region provides greater insight into the aliphatic structures of the acritarchs. The CH 2 /CH 3 intensity ratio can be used to assess the relative chain length and degree of branching. Organic material in the Tanarium conoideum consists of straight long chain hydrocarbons, while the other acritarchs contain hydrocarbons consisting of short chains that are highly branched. In this study it was found that Raman spectroscopy does not provide additional information about biopolymer composition of Proterozoic acritarchs, but rather offers complementary data regarding the aromaticity and degree of saturation of the macromolecular structure of acritarch cysts
