Isoprenoid Content Research Articles

Non-destructive optical indices to estimate isoprenoids with nutritional value in packed rocket and spinach

The quantification of phytochemicals with nutritional benefits relies on accuracy yet time-consuming, expensive and destructive methodologies. In contrast, optical indices widely employed in disciplines such as ecology can serve as fast, low-cost, and non-destructive tools for tracking pigment changes. However, their potential application in postharvest phases and commercialization (i.e., supermarkets) remains underexplored. In this context, this work aimed to investigate the feasibility of using the normalized difference vegetation index (NDVI), the chlorophyll content index (CCI) and the photochemical reflectance index (PRI) to estimate phytochemicals of nutraceutical interest (chlorophylls, carotenoids and tocopherols). A fully factorial and randomized experimental design (combining different illumination, packaging, and collecting time) was conducted in two green leafy packaged vegetables (rocket and spinach). With this design that induced differences in physiological parameters a database with variable content of isoprenoids (carotenoids, chlorophylls, and tocopherols) based on treatments was created. By establishing correlations and models between isoprenoids and optical indices, the NDVI was revealed as a valuable tool to estimate chlorophyll content in both species, while the PRI tracked both tocopherol and carotenoid (except for β-carotene) content. Taking this approach, estimation of the sum of total carotenoids and tocopherols was achieved using the PRI. This study confirms the possibility of extending the use of the NDVI and PRI to real-time nutritional monitoring in different stages of production and commercialization. A future application envisions integrating this technology into refrigerators for enhanced consumer access to nutritional information.

Changing biosynthesis of terpenoid percursors in rice through synthetic biology.

Many highly valued chemicals in the pharmaceutical, biotechnological, cosmetic, and biomedical industries belong to the terpenoid family. Biosynthesis of these chemicals relies on polymerization of Isopentenyl di-phosphate (IPP) and/or dimethylallyl diphosphate (DMAPP) monomers, which plants synthesize using two alternative pathways: a cytosolic mevalonic acid (MVA) pathway and a plastidic methyleritritol-4-phosphate (MEP) pathway. As such, developing plants for use as a platform to use IPP/DMAPP and produce high value terpenoids is an important biotechnological goal. Still, IPP/DMAPP are the precursors to many plant developmental hormones. This creates severe challenges in redirecting IPP/DMAPP towards production of non-cognate plant metabolites. A potential solution to this problem is increasing the IPP/DMAPP production flux in planta. Here, we aimed at discovering, understanding, and predicting the effects of increasing IPP/DMAPP production in plants through modelling. We used synthetic biology to create rice lines containing an additional ectopic MVA biosynthetic pathway for producing IPP/DMAPP. The rice lines express three alternative versions of the additional MVA pathway in the plastid, in addition to the normal endogenous pathways. We collected data for changes in macroscopic and molecular phenotypes, gene expression, isoprenoid content, and hormone abundance in those lines. To integrate the molecular and macroscopic data and develop a more in depth understanding of the effects of engineering the exogenous pathway in the mutant rice lines, we developed and analyzed data-centric, line-specific, multilevel mathematical models. These models connect the effects of variations in hormones and gene expression to changes in macroscopic plant phenotype and metabolite concentrations within the MVA and MEP pathways of WT and mutant rice lines. Our models allow us to predict how an exogenous IPP/DMAPP biosynthetic pathway affects the flux of terpenoid precursors. We also quantify the long-term effect of plant hormones on the dynamic behavior of IPP/DMAPP biosynthetic pathways in seeds, and predict plant characteristics, such as plant height, leaf size, and chlorophyll content from molecular data. In addition, our models are a tool that can be used in the future to help in prioritizing re-engineering strategies for the exogenous pathway in order to achieve specific metabolic goals.

MEP pathway products allosterically promote monomerization of deoxy-D-xylulose-5-phosphate synthase to feedback-regulate their supply

Isoprenoids are a very large and diverse family of metabolites required by all living organisms. All isoprenoids derive from the double-bond isomers isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP), which are produced by the methylerythritol 4-phosphate (MEP) pathway in bacteria and plant plastids. It has been reported that IPP and DMAPP feedback-regulate the activity of deoxyxylulose 5-phosphate synthase (DXS), a dimeric enzyme that catalyzes the main flux-controlling step of the MEP pathway. Here we provide experimental insights into the underlying mechanism. Isothermal titration calorimetry and dynamic light scattering approaches showed that IPP and DMAPP can allosterically bind to DXS in vitro, causing a size shift. In silico ligand binding site analysis and docking calculations identified a potential allosteric site in the contact region between the two monomers of the active DXS dimer. Modulation of IPP and DMAPP contents in vivo followed by immunoblot analyses confirmed that high IPP/DMAPP levels resulted in monomerization and eventual aggregation of the enzyme in bacterial and plant cells. Loss of the enzymatically active dimeric conformation allows a fast and reversible reduction of DXS activity in response to a sudden increase or decrease in IPP/DMAPP supply, whereas aggregation and subsequent removal of monomers that would otherwise be available for dimerization appears to be a more drastic response in the case of persistent IPP/DMAPP overabundance (e.g., by a blockage in their conversion to downstream isoprenoids). Our results represent an important step toward understanding the regulation of the MEP pathway and rational design of biotechnological endeavors aimed at increasing isoprenoid contents in microbial and plant systems.

Anti-Hyperglycemic and Anticholinergic Effects of Natural Antioxidant Contents in Edible Flowers.

In this study, 16 selected edible flowers were evaluated for their content of bioactive compounds (polyphenols, carotenoids, triterpenoids) and for their anti-diabetic (ability to inhibit α-amylase and α-glucosidases) and anti-aging (ability to inhibit acetylcholinesterase and butyrylcholinesterase) activities. Most of the flowers analyzed in this study have not been examined in this respect until now. Contents of the analyzed bioactive compounds differed significantly among the flowers. In particular, the highest contents of carotenoids and triterpenoids were determined in marigold, arnica, lavender, and daisy; in turn, the highest contents of phenolic acids, procyanidin polymers, and total polyphenols were assayed in hawthorn, primrose, and linden blossom. There was a positive correlation between the content of isoprenoids in edible flowers and their anti-aging activity, and between the content of polymeric procyanidins and flowers’ ability to inhibit α-glucosidase. In conclusion, edible flowers may be used to produce functional foods as well as for medical purposes.

Contrasting patterns of hormonal and photoprotective isoprenoids in response to stress in Cistus albidus during a Mediterranean winter.

Seasonal accumulation of hormonal and photoprotective isoprenoids, particularly α-tocopherol, carotenoids and abscisic acid, indicate their important role in protecting Cistus albidus plants from environmental stress during a Mediterranean winter. The high diurnal amounts of α-tocopherol and xanthophylls 3h before maximum light intensity suggest a photoprotective response against the prevailing diurnal changes. The timing to modulate acclimatory/defense responses under changing environmental conditions is one of the most critical points for plant fitness and stress tolerance. Here, we report seasonal and diurnal changes in the contents of isoprenoids originated from the methylerythritol phosphate pathway, including chlorophylls, carotenoids, tocochromanols, and phytohormones (abscisic acid, cytokinins, and gibberellins) in C. albidus during a Mediterranean winter. Plants were subjected not only to typically low winter temperatures but also to drought, as shown by a mean plant water status of 54% during the experimental period. The maximum PSII efficiency, however, remained consistently high (Fv/Fm > 0.8), proving that C. albidus had efficient mechanisms to tolerate combined stress conditions during winter. While seasonal α-tocopherol contents remained high (200-300µg/g DW) during the experimental period, carotenoid contents increased during winter attaining maximum levels in February (minimum air temperature ≤ 5°C for 13days). Following the initial transient increases of bioactive trans-zeatin (about fivefold) during winter, the increased abscisic acid contents proved its important role during abiotic stress tolerance. Diurnal amounts of α-tocopherol and xanthophylls, particularly lutein, zeaxanthin and neoxanthin including the de-epoxidation state, reached maximum levels as early as 2h after dawn, when solar intensity was 68% lower than the maximum solar radiation at noon. It is concluded that (1) given their proven antioxidant properties, both α-tocopherol and carotenoids seem to play a crucial role protecting the photosynthetic apparatus under severe stress conditions; (2) high seasonal amounts of abscisic acid indicate its important role in abiotic stress tolerance within plant hormones, although under specific environmental conditions, accumulation of bioactive cytokinins appears to be involved to enhance stress tolerance; (3) the concerted diurnal adjustment of α-tocopherol and xanthophylls as early as 3h before maximum light intensity suggests that plants anticipated the predictable diurnal changes in the environment to protect the photosynthetic apparatus.

Isoprenoid biosynthesis in the diatom Haslea ostrearia.

Diatoms are eukaryotic, unicellular algae that are responsible for c. 20% of the Earth's primary production. Their dominance and success in contemporary oceans have prompted investigations on their distinctive metabolism and physiology. One metabolic pathway that remains largely unexplored in diatoms is isoprenoid biosynthesis, which is responsible for the production of numerous molecules with unique features. We selected the diatom species Haslea ostrearia because of its characteristic isoprenoid content and carried out a comprehensive transcriptomic analysis and functional characterization of the genes identified. We functionally characterized one farnesyl diphosphate synthase, two geranylgeranyl diphosphate synthases, one short-chain polyprenyl synthase, one bifunctional isopentenyl diphosphate isomerase - squalene synthase, and one phytoene synthase. We inferred the phylogenetic origin of these genes and used a combination of functional analysis and subcellular localization predictions to propose their physiological roles. Our results provide insight into isoprenoid biosynthesis in H.ostrearia and propose a model of the central steps of the pathway. This model will facilitate the study of metabolic pathways of important isoprenoids in diatoms, including carotenoids, sterols and highly branched isoprenoids.

The radiation-induced fragmentation of high-molecular-weight isoprenoid hydrocarbons present in high-boiling petroleum fractions

The radiation-induced fragmentation of squalane, phytane and high-molecular-weight isoprenoid hydrocarbons present in high-boiling petroleum fractions was investigated. The structure of the isoprenoids was determined by 13C NMR spectroscopy, and the identification and quantification of their radiolysis products was performed by gas chromatography. It was found that the vast majority of high-molecular-weight isopranes present in the samples have a regular (i.e., head-to-tail) structure and that their terminal groups have methyl branches at positions 2,6,10,…; 3,7,11,…; 4,8,12,…and 6,10,14,…The ratio of radiation-chemical yields of fragment isoprenoids to that of n-alkanes (G(isop)/G(n-alkane)) correlates well with the isoprenoid content in the sample. Based on the concentration distribution of radiolytic products, an attempt was made to reconstruct the quantitative ratio of isoprenoid end groups in the samples.

Isoprenoids composition and colour to differentiate virgin olive oils from a specific mill

The objective of this work was verify if, based on the concentration of some key isoprenoids and the colour, olive oils from a specific mill could be differentiated from those from other mills by linear discriminant analysis. The isoprenoids studied were β-carotene, lutein, α-tocopherol, β-sitosterol, pheophytin a and squalene, which are isoprenoids of interest in food science and nutrition. 88% of correct classification was obtained by linear discriminant analysis and, therefore, a good differentiation was achieved. This fact can reveal the impact of the conditions of elaboration of each particular mill on the isoprenoid content of the olive oil and therefore on its colour, which is a characteristic of foods with a high effect on consumers.

Bias in leaf dry mass estimation after oven-drying isoprenoid-storing leaves

Air-drying, cooling and freezing leaf samples rich in isoprenoid content evaporates isoprenoids and consequently causes an underestimation of the leaf dry matter content. Foliage isoprenoid content or essential oil content is a key plant characteristic important in plant science, but also for food, cosmetic and pharmaceutical industry. Commonly, the amount of foliage chemicals is normalized with respect to leaf dry mass (content per dry mass). However, the protocols for foliage drying have received little attention. In particular, volatile and semi-volatile isoprenoids and other compounds with low boiling point may partly volatilize during drying, reducing both isoprenoid and leaf dry matter contents, thereby potentially underestimating the content of volatiles and overestimating that of non-volatile constituents. Three leaf preservation (flash freezing in liquid nitrogen, freezing at −82 and at −20 °C, and cooling at 4 °C) and two leaf desiccation (freeze-drying at −54 °C and 1.2 mbar, and air-drying at 30, 40 60, 70, 80, 100, 110, 125, 150, 200, and 300 °C) procedures were applied to replicate leaves, and the leaf dry matter content as well as the leaf isoprenoid content was measured afterwards. The results of this experiment suggested that freeze-drying method (FD) performed the best leaf isoprenoid preservation followed by FF method, whilst air-drying methods performed a dramatic isoprenoid loss in the leaf samples, as well as preserving the leaves at freezing and cooling temperatures. Leaf isoprenoid content and leaf dry to fresh mass ratio were correlated and there were evidences of leaf dry matter content (LDMC) miscalculation in isoprenoid-storing species when using traditional air-drying methods and preservation of samples, possibly related to the isoprenoid loss as well as other volatile compounds. In addition, losses of high C content volatiles and respiration of sugars and carbohydrate pyrolysis with low carbon content may differently affect the bulk leaf C content.

Helper component-proteinase enhances the activity of 1-deoxy-D-xylulose-5-phosphate synthase and promotes the biosynthesis of plastidic isoprenoids in Potato virus Y-infected tobacco.

Virus-infected plants show strong morphological and physiological alterations. Many physiological processes in chloroplast are affected, including the plastidic isoprenoid biosynthetic pathway [the 2C-methyl-D-erythritol-4-phosphate (MEP) pathway]; indeed, isoprenoid contents have been demonstrated to be altered in virus-infected plants. In this study, we found that the levels of photosynthetic pigments and abscisic acid (ABA) were altered in Potato virus Y (PVY)-infected tobacco. Using yeast two-hybrid assays, we demonstrated an interaction between virus protein PVY helper component-proteinase (HC-Pro) and tobacco chloroplast protein 1-deoxy-D-xylulose-5-phosphate synthase (NtDXS). This interaction was confirmed using bimolecular fluorescence complementation (BiFC) assays and pull-down assays. The Transket_pyr domain (residues 394-561) of NtDXS was required for interaction with HC-Pro, while the N-terminal region of HC-Pro (residues 1-97) was necessary for interaction with NtDXS. Using in vitro enzyme activity assays, PVY HC-Pro was found to promote the synthase activity of NtDXS. We observed increases in photosynthetic pigment contents and ABA levels in transgenic plants with HC-Pro accumulating in the chloroplasts. During virus infection, the enhancement of plastidic isoprenoid biosynthesis was attributed to the enhancement of DXS activity by HC-Pro. Our study reveals a new role of HC-Pro in the host plant metabolic system and will contribute to the study of host-virus relationships.

Fluid circulation and formation of minerals and bitumens in the sedimentary rocks of the Outer Carpathians – Based on studies on the quartz–calcite–organic matter association

Different methods have been used to examine minerals and/or solid bitumens in three adjacent Carpathian regions of Poland, Ukraine and Slovakia. The minerals fill smaller and larger veins and cavities, where they occur either together or separately. They usually co-occur with the solid bitumens. All δ13CPDB values measured for calcite lie in a relatively wide interval between −6.25‰ and +1.54‰, while most values fall into the narrower interval from below 0 to about −3‰. The general range of calcite δ18O results for the whole studied region is between +17.13‰ and +25.23‰ VSMOW or from about −11 to −5‰ VPDB, while the majority of these values are between +20.0 and 23.5‰ VSMOW (−10.53 and −8.00‰ PDB, respectively). δ18OVSMOW results for quartz vary between +23.2 and 27.6. The carbonate percentage determined in some samples falls between from <2% CaCO3 to >90% CaCO3, while the TOC values changes from 0.09% to over 70%.The aliphatic fraction predominates in all studied samples, mainly in bitumens and oils. The composition of the aliphatic fraction is relatively homogeneous and points to a strong aliphatic, oil-like paraffin character of the bitumens. Such a composition is characteristic of the Carpathian oils and different from the rocks studied that contain the higher percentage of a polar fraction. The content of the aliphatic fraction in bitumens is only slightly higher than that in two oils used for comparison. The distribution of n-alkanes is variable in rocks, solid bitumens as well as inclusions in quartz and calcite. Two groups of bitumens may be distinguished. Those with a predominance of long-chain n-alkanes in the C25–C27 interval (in some cases from C23–C25 and without or with a very low concentration of short-chain n-alkanes in the interval of C14–C21) show also a high content of isoprenoids i.e. of pristane (Pr) and phytane (Ph). In all but one bitumen samples, Pr predominates over Ph. The second group comprises oils and rock samples with a characteristic predominance of short-chain n-alkanes in the interval from C13–C19 and a low percentage of the long-chain n-alkanes from the n-C27–n-C33 interval. Pristane and phytane exhibit a concentration comparable to that of C17 and C18n-alkanes with a Pr predominance over Ph. Due to high maturity, only small amounts of the most stable compounds from the hopane group have been observed in the samples, also oleanane in one case. Among the aromatic hydrocarbons, phenanthrene and its methyl- and dimethyl-derivatives are dominant in bitumens, source rocks and inclusions in calcite and quartz. Occurrence of cyclohexylbenzene and its alkyl-derivatives as well as cyclohexylfluorenes in solid bitumens suggest that they formed from oil accumulations under the influence of relatively high temperatures in oxidizing conditions.Homogenization temperatures for aqueous/brine inclusions in quartz within the Dukla and Silesian units (Polish and Ukrainian segments) are between 125 and 183.9 °C, while salinities are low in the interval of 0.2–5.5 wt% NaCl eq. The inclusions in calcite homogenize at higher temperatures of almost 200 °C and the brine displays higher salinity than the fluid in the quartz. Two quartz generations may be distinguished by inclusion and isotope characteristics and the macroscopic diversity. Oil inclusions homogenize at 95 °C. One phase inclusions in quartz contain methane, CO2 and nitrogen in variable proportions.

Overexpression of Brassica juncea wild‐type and mutant HMG‐CoA synthase 1 in Arabidopsis up‐regulates genes in sterol biosynthesis and enhances sterol production and stress tolerance

Brassica juncea 3-hydroxy-3-methylglutaryl-CoA synthase (HMGS) is encoded by four isogenes (BjHMGS1-BjHMGS4). In vitro enzyme assays had indicated that the recombinant BjHMGS1 H188N mutant lacked substrate inhibition by acetoacetyl-CoA (AcAc-CoA) and showed 8-fold decreased enzyme activity. The S359A mutant demonstrated 10-fold higher activity, while the H188N/S359A double mutant displayed a 10-fold increased enzyme activity and lacked inhibition by AcAc-CoA. Here, wild-type and mutant BjHMGS1 were overexpressed in Arabidopsis to examine their effects in planta. The expression of selected genes in isoprenoid biosynthesis, isoprenoid content, seed germination and stress tolerance was analysed in HMGS overexpressors (OEs). Those mRNAs encoding enzymes 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR), sterol methyltransferase 2 (SMT2), delta-24 sterol reductase (DWF1), C-22 sterol desaturase (CYP710A1) and brassinosteroid-6-oxidase 2 (BR6OX2) were up-regulated in HMGS-OEs. The total sterol content in leaves and seedlings of OE-wtBjHMGS1, OE-S359A and OE-H188N/S359A was significantly higher than OE-H188N. HMGS-OE seeds germinated earlier than wild-type and vector-transformed controls. HMGS-OEs further displayed reduced hydrogen peroxide (H(2) O(2) )-induced cell death and constitutive expression of salicylic acid (SA)-dependent pathogenesis-related genes (PR1, PR2 and PR5), resulting in an increased resistance to Botrytis cinerea, with OE-S359A showing the highest and OE-H188N the lowest tolerance. These results suggest that overexpression of HMGS up-regulates HMGR, SMT2, DWF1, CYP710A1 and BR6OX2, leading to enhanced sterol content and stress tolerance in Arabidopsis.

The influence of leaf water content and isoprenoids on flammability of some Mediterranean woody species

The impact of water content and isoprenoids on leaf flammability was studied. Field and laboratory experiments were carried out on monoterpene-emitting evergreen broad-leaved species (Quercus ilex, Quercus suber); a needle-leaved species (Pinus halepensis) that emits and stores monoterpenes; an evergreen species (Myrtus communis) that emits isoprene but stores monoterpenes; and a deciduous species (Quercus pubescens) that emits isoprene. Photosynthesis, leaf water content (LWC) and isoprenoid emission were measured. Isoprenoid content was calculated. Temperatures of visible smoke, incandescence and flame appearance were recorded. The LWC significantly correlated with both photosynthesis and isoprenoid emissions. Linear correlation and factorial analysis revealed a positive correlation between temperature of flame appearance and LWC and a negative relationship between temperature of flame appearance and isoprenoid emission. Multiple regression analysis indicated that the temperature of flame appearance was reduced in broadleaved monoterpene-emitting species. In monoterpene emitters, the temperature of flame appearance depended for ~65% on LWC, whereas monoterpene emissions explained ~35% of the dependency. P. halepensis and M. communis, storing high levels of isoprenoids, ignited at high humidity. The results may be explained if isoprenoids indeed facilitate leaf ignition but, being dissolved in water, isoprenoids are also an indicator of a high water content that decreases flammability.

Rat HMGCoA reductase activation in thioacetamide-induced liver injury is related to an increased reactive oxygen species content

In thioacetamide-induced liver injury a modification of isoprenoid content and an increase of reactive oxygen species has been described. We have examined how reactive oxygen species influence the 3-hydroxy-3-methylglutaryl coenzyme A reductase, the rate limiting enzyme of the isoprenoid biosynthetic pathway, to verify if changes of that enzyme activity are involved in the changed lipid composition of the liver. In chronic and acute thioacetamide-treated rat liver we measured the reactive oxygen species content, the activation state and K(M), the level and degradation rate of the hepatic reductase, its short term regulatory enzymes and the liver lipid profile. In thioacetamide-treated rat liver, the reactive oxygen species content is high and the reductase is fully activated with no modifications in its K(M) and its short term regulatory enzymes. The reductase level is reduced in chronic thioacetamide treated rats and its degradation rate is altered. The data show a relationship between reactive oxygen species production and altered 3-hydroxy-3-methylglutaryl coenzyme A reductase activity. It is suggested that reducing the levels of reactive oxygen species may improve the altered lipid profile found in liver injury.

Technical advance: application of high-performance liquid chromatography with photodiode array detection to the metabolic profiling of plant isoprenoids.

The application of high-performance liquid chromatography (HPLC) using a C30 reverse-phase stationary matrix has enabled the simultaneous separation of carotenes, xanthophylls, ubiquinones, tocopherols and plastoquinones in a single chromatogram. Continuous photodiode array (PDA) detection ensured identification and quantification of compounds upon elution. Applications of the method to the characterization of transgenic and mutant tomato varieties with altered isoprenoid content, biochemical screening of Arabidopsis thaliana, and elucidation of the modes of action of bleaching herbicides are described to illustrate the versatility of the procedure.

Application of high‐performance liquid chromatography with photodiode array detection to the metabolic profiling of plant isoprenoids

SummaryThe application of high‐performance liquid chromatography (HPLC) using a C30 reverse‐phase stationary matrix has enabled the simultaneous separation of carotenes, xanthophylls, ubiquinones, tocopherols and plastoquinones in a single chromatogram. Continuous photodiode array (PDA) detection ensured identification and quantification of compounds upon elution. Applications of the method to the characterization of transgenic and mutant tomato varieties with altered isoprenoid content, biochemical screening of Arabidopsis thaliana, and elucidation of the modes of action of bleaching herbicides are described to illustrate the versatility of the procedure.

Measurement of isoprenoid content in leaves of Mediterranean Quercus spp. by a novel and sensitive method and estimation of the isoprenoid partition between liquid and gas phase inside the leaves

We useda novel, simple and sensitive method to extract isoprenoids contained in the leaves and compared emission and content of isoprenoids in the leaves of three Mediterranean oak species emitting isoprene ( Quercus pubescens), monoterpenes ( Quercus ilex) or non-emitting isoprenoids ( Quercus cerris). The content is qualitatively consistent with the emission of isoprenoids by Quercus spp. However, the fraction of isoprenoids in the gas phase was estimated to be ≈0.02 and 5% of the total content for monoterpenes and isoprene, respectively. On the other hand, the content of monoterpenes in the leaf was much higher than that of isoprene and particularly rich of compounds which can hardly be detected in an emission such as linalool. It is concluded that isoprenoids are contained in temporary pools and that the different partition between gas and liquid phases plays an important role in determining the pool size in isoprene and monoterpene-emitting oaks. The pools of isoprenoid-emitting oaks sustain the emission for few minutes when isoprenoid formation is prevented, which rules out the presence of specialized organs for isoprenoid storage and are absent altogether in non-emitting species.

Application of Porphyrin and Other Biological Marker Geochemistry to Paleoenvironmental Assessment--Pennsylvanian Black Shales, Northern Denver Basin: ABSTRACT

Thin, Middle Pennsylvanian (Desmoinesian) organic-rich black shales underlie much of the northern Denver basin. During the Desmoinesian, the present-day area of the Nebraska panhandle was a shallow, at times highly saline restricted sea. In contrast, black shale deposition occurred in a marine environment with normal salinity (open marine) in northeastern Colorado. About eight individual black shale beds are present in the Desmoinesian section in both the restricted basin and open-marine settings, separated vertically by carbonate-evaporate rocks in the restricted basin and by predominantly carbonate rocks in the open-marine sequence. Preservation of high amounts of organic matter occurred in black shales deposited in both the restricted basin and open-marine settings. Chloroform-extractable organic matter (bitumen) concentrations are typically in the range of 4,000 to 8,000 ppm, and total organic carbon content (TOC) is as high as 20 wt. %. However, the composition of the bitumen contained in stratigraphically equivalent black shales is variable and is correlative to differences in paleoenvironmental conditions during sedimentation in the restricted and open-marine basins. Total porphyrin concentration (ppm relative to bitumen) is typically 10-100 times greater in the restricted basin compared to the open marine. The total porphyrin concentration (vanadyl + nickel + carboxyl) correlates with totalmore » sulfur content in the rocks (normalized to TOC) and C{sub 14}-C{sub 20} aryl isoprenoid content. The coincidence of high porphyrin and aryl isoprenoid concentration, along with high S/C ratios, is explained by differences in water column chemistry of the restricted basin and open-marine environments during sedimentation. The restricted basin was characterized by a stratified water column with euxinic conditions below the chemocline and a thin overlying oxic water column.« less

Photoautotrophic Suspension Cultures I-Obtention of Photoautotrophic Cultures from Euphorbia characias L.

Summary The aim of this study was to obtain photoautotrophic suspension cultures from Euphorbia characias L., a Mediterranean species with high isoprenoid content. Calluses were initiated in photomixotrophy on a modified Murashige and Skoog (MS) medium supplemented with NAA and BAP. Selection and subculture led to chlorophyllous and friable calluses which were used to initiate suspension cultures. Batch cultures were performed in 250 ml closed conical flasks and analysed with respect to cell density, sugar consumption and chlorophyll content. Cells in the early stationary phase exhibited good photosynthetic potency, allowing transfer into bioreactors where cells have been grown photoautotrophically since February 1984.

FOSSIL LATICIFERS FROM EOCENE BROWN COAL DEPOSITS OF THE GEISELTAL

Thick mats of cellular remains from Eocene brown coal deposits of the Geiseltal near Halle, DDR, were determined to be fossil nonarticulated laticifers. Nuclear magnetic resonance analyses of intact strands showed they consisted of eis‐1,4‐configuration rubber representing the polymerized isoprenoid contents of individual laticifers. Only remains of laticifers are present; other cells are absent as a result of biodegradation. The long laticifers, often with a surrounding cell wall, retained a tubular shape during their preservation. The isoprenoid content, which filled the entire lumen, possessed a cribriform structural character. The interstices within the rubber represent areas of former protoplasm of the cell. Various configurations in the protoplasm molded by the rubber during the initial phase of fossilization appear as negative images of former nuclei, organelles, and possibly membrane surfaces. The laticifer axes possess branches of several configurations comparable in morphology to those in branched, nonarticulated laticifers in extant plants. Acetone extracts of the rubber contents analyzed by gas‐liquid chromatography identified the presence of several hydrocarbons which form a characteristic profile for the laticifer. It is suggested that the distinctive cellular micromorphology, rubber configuration, and hydrocarbon profile of these laticifers can be employed as markers in comparative studies with extant plants to identify the generic or species origin of these laticifers.