Carotenoids and carotenoid metabolism in Carcinus maenas (Crustacea: Decapoda)

The carotenoid pigments of the hepatopancreas, ovaries and epidermis of Carcinus maenas were investigated. The following pigments were identified: β-carotene, δ-carotene, echinenone, isocryptoxanthin, canthaxanthin, lutein, zeaxanthin, flavoxanthin and astacene.
The relative abundance of these pigments in the three tissues and the presence of possible hydroxy and keto intermediates suggest the metabolism of astaxanthin from β-carotene. The metabolic pathway in Carcinus is discussed in relation to recent studies on other invertebrates.     

Nature and Distribution of Carotenoid Pigments in Astasia ocellata

SYNOPSIS. The pigments synthesized by Astasia ocellata include α- and ε-carotene, 4-keto-β-carotene (echinenone), and 4,4'-diketo-β-carotene (canthaxanthin); 4-keto-α-carotene, accounting for about half the pigment in the cells, was tentatively identified; a strongly adsorbed keto-carotenoid, accounting for 25% of the pigments and bearing some similarities to astacin, polytomaxanthin and phoenicoxanthin, was also found.     

Irradiance levels affect growth parameters and carotenoid pigments in kale and spinach grown in a controlled environment

Carotenoids play critical roles in both light harvesting and energy dissipation for the protection of photosynthetic structures. However, limited research is available on the impact of irradiance on the production of secondary plant compounds, such as carotenoid pigments. Kale ( Brassica oleracea L.) and spinach ( Spinacia oleracea L.) are two leafy vegetables high in lutein and β-carotene carotenoids. The objectives of this study were to determine the effects of different irradiance levels on tissue biomass, elemental nutrient concentrations, and lutein β-carotene and chlorophyll (chl) pigment accumulation in the leaves of kale and spinach. 'Winterbor' kale and 'Melody' spinach were grown in nutrient solution culture in growth chambers at average irradiance levels of 125, 200, 335, 460, and 620 μmol m⁻² s⁻¹. Highest tissue lutein β-carotene and chls occurred at 335 μmol m⁻² s⁻¹ for kale, and 200 μmol m⁻² s⁻¹ for spinach. The accumulations of lutein and β-carotene were significantly different among irradiance levels for kale, but were not significantly different for spinach. However, lutein and β-carotene accumulation was significant for spinach when computed on a dry mass basis. Identifying effects of irradiance on carotenoid accumulation in kale and spinach is important information for growers producing these crops for dry capsule supplements and fresh markets.     

Response of senescing cotyledons of clusterbean to water stress in moderate and low light: Possible photoprotective role of beta-carotene

Senescence of clusterbean ( Cyamopsis tetragonoloba L.) cotyledons in moderate light (12 W m⁻²) brings about a loss in the pigments, enhanced lipid peroxidation and a decline in PS II photochemical activity without any loss either in Dl protein or in the level of β -carotene. The senescence syndrome is aggravated in the cotyledons of water-stressed seedlings with an increase in thylakoid lipid peroxidation, a decline in the level of β -carotene and a quantitative loss in the Dl protein. Loss of the protein, however, is arrested in the seedlings experiencing water stress at low light (3 W m⁻²) intensity that correlates with the stability in the level of β - carotene and a slow rate of lipid peroxidation. Loss of the protein in moderate light is attributed to water-stress sensitized photoinhibitory damage. The data on changes in the components of xanthophyll cycle suggest the low activity of the cycle both during senescence and water stress. It is, therefore, concluded that β -carotene may contribute to the assembly and stability of the Dl protein during senescence and water stress in clusterbean cotyledons.     

Leaf senescence in a non-yellowing mutant of Festuca pratensis: Degradation of carotenoids

The loss of pigments was assessed in detached leaves of Festuca pratensis Huds. kept in permanent darkness. Two genotypes, a normal yellowing cultivar Rossa and a non-yellowing mutant Bf 993 were compared with each other. Analysis of individual pigments, chlorophylls. β-carotene, lutein, violaxanthin and neoxanthin was performed using HPLC. In the non-yellowing genotype the high retention of chlorophylls was associated with an equally high retention of total carotenoids. Although the two genotypes differ markedly with regard to the rate of pigment loss, the ratios of yellow to green pigments did not change significantly during dark-induced senescence. At the end of the senescence period β-carotene was retained to a higher degree than the xanthophylls, particularly in the yellowing genotype. In the mutant leaves the ratio of chlorophyll a to b remained nearly constant, whereas in leaves of the normal genotype a preferential retention of chlorophyll b was observed towards the end of the senescence period. It is concluded that the thylakoids of the non-yellowing genotype retain all the principal components of protein-pigment complexes, i.e. chlorophylls, carotenoids and apoproteins. Possible explanations for the stability of these complexes in the mutant are discussed.     

Molecular evolution of carotenoid biosynthesis from bacteria to plants

β-Carotene and derivatives are important pigments in plant photosynthesis. They are found not only in green plants but also accumulate in archea, prokaryotes and fungi. For β -carotene biosynthesis, enzymes are necessary to catalyse the formation of phytoene, several desaturation steps and cyclization reactions. This review is focused on the molecular phylogeny of the enzymes, the genes involved and their diversity. It outlines how genes and enzymes from prokaryotes and archea were modified to give rise to the corresponding plant constituents. In the cases of phytoene synthase, a direct line of evolution can be drawn. For other carotenogenic enzymes, new genes and enzymes have been acquired at certain stages of evolution. In addition, phytoene desaturases and lycopene cyclases are examples of convergent evolution of different types of enzymes, which are structurally completely unrelated but functionally identical. Finally, several gene duplications led to homologous enzymes with different catalytic functions including those involved in the synthesis of α -carotene.     

Algal and bacterial pigments in non-laminated lacustrine sediment: Studies of their sedimentation, degradation and stratigraphy

Abstract Natural phyto- and bacterioplankton populations of Lake Vechten (the Netherlands) were subjected to darkness under oxic and anoxic conditions at in situ temperatures in order to test the stability in time of their photosynthetic pigments. Furthermore, sedimentary fluxes and concentrations of pigments were estimated in (respectively) sediment trap catches and at the sediment-water interphase in order to measure the pigment breakdown upon burial into the sediment. The chlorophylls and most of the xanthophylls showed substantial losses of 20% to 60% in the incubation experiments as well as in the surficial sediment. β-Carotene, okenone and echinenone were most stable (2–10% losses); fucoxanthin and peridinin were degraded extensively; alloxanthin and zeaxanthin held an intermediate position as did the bacteriochlorophylls. Trends in sediment profiles of pigments were compared with limnological data obtained during the enhanced eutrophication of the lake. Evidence was provided that the β-carotene profile closely followed the increase of phytoplankton biomass. Although susceptible to substantial degradation, several profiles of pigments and of pigment ratios could be related in a qualitative way to biomass and to shifts in species composition which occurred as a result of the changing ecological conditions in the lake.     

LOW-TEMPERATURE-INDUCED SYNTHESIS OF α-CAROTENE IN THE MICROALGA DUNALIELLA SALINA (CHLOROPHYTA)

The microalga Dunaliella salina (Teo.) is well known as an accumulator of β-carotene (β,β-carotene) when subjected to growth-limiting conditions (e.g. exposure to high irradiances). In addition, the carotenoid α-carotene (β,ε-carotene) may also be synthesized and subsequently accumulated by this alga under specific growth conditions. The main factor in stimulating the synthesis of this carotene was determined to be exposure to lower than optimum temperatures for algal growth. A 7.5-fold increase in the levels of α-carotene was observed when the temperature was decreased from 34 to 17° C, whilst levels of β-carotene were unaltered. The accumulation of α-carotene was unaffected by irradiance, although its isomeric composition was greatly altered by light levels. The proportion of 9- cis α-carotene increased from 15% to 45% of total α-carotene when the irradiance was decreased from 260 to 50 μmol·m⁻²·s⁻¹. Exposure to higher irradiances had little influence on the isomeric composition of this carotenoid. A reduction in growth temperature did not influence the isomeric composition of α-carotene. Nutrient status (nitrogen and phosphate) had no effect on either the content or isomeric composition of α-carotene accumulated by D. salina.     

Lipid peroxidation in and photo-damage to a light-sensitive chlorescence pea mutant

Leaves of 10- to 12-day-old chlorescence lethal Pisum sativum L. mutant are similar to control plants with respect to the content of chlorophylls, carotenoids, fatty acids and α-tocopherol. Subsequent development of the mutant under high irradiation resulted in th destruction of the photosynthetic pigments, polyunsaturated fatty acids, α-tocopherol, and also in the accumulation of liposoluble fluorescent products. No increase in the level of malondialdehyde was observed. In chloroplasts isolated from mutant plants the contents of chlorophyll a and β-carotene were decreased to a greater extent than the more oxidized pigments (xanthophylls and chlorophyll b ). The data obtained are discussed with special reference to the role of lipid peroxidation in the injury of plant cells under the action of visible light and to the antioxidative mechanisms stabilizing photosynthetic membranes.     

Carotenoids in some ultraviolet mutants of Epicoccum nigrum link

Summary Mutants were produced by ultraviolet irradiation of the mould Epicoccum nigrum Link. The qualitative and quantitative formation of carotenoid pigments was studied. In addition to the four carotenoids present in the wild-type strain 5-I-3 several other carotenoids were isolated and identified.The presence of these pigments is discussed. The results support the proposed pathway for the biosynthesis of rhodoxanthin, 3,3-diketo-retro--carotene, from -carotene.     

Simultaneous accumulation of astaxanthin and β-carotene in Chlamydomonas reinhardtii by the introduction of foreign β-carotene hydroxylase gene in response to high light stress

Biotechnology Letters - Carotenoids are important photosynthetic pigments with many physiological functions, nutritional properties and high commercial value. β-carotene hydroxylase is one of...     

Tissue-specific accumulation of carotenoids in carrot roots

Raman spectroscopy can be used for sensitive detection of carotenoids in living tissue and Raman mapping provides further information about their spatial distribution in the measured plant sample. In this work, the relative content and distribution of the main carrot (Daucus carota L.) root carotenoids, α-, β-carotene, lutein and lycopene were assessed using near-infrared Fourier transform Raman spectroscopy. The pigments were measured simultaneously in situ in root sections without any preliminary sample preparation. The Raman spectra obtained from carrots of different origin and root colour had intensive bands of carotenoids that could be assigned to β-carotene (1,520 cm⁻¹), lycopene (1,510 cm⁻¹) and α-carotene/lutein (1,527 cm⁻¹). The Raman mapping technique revealed detailed information regarding the relative content and distribution of these carotenoids. The level of β-carotene was heterogeneous across root sections of orange, yellow, red and purple roots, and in the secondary phloem increased gradually from periderm towards the core, but declined fast in cells close to the vascular cambium. α-carotene/lutein were deposited in younger cells with a higher rate than β-carotene while lycopene in red carrots accumulated throughout the whole secondary phloem at the same level. The results indicate developmental regulation of carotenoid genes in carrot root and that Raman spectroscopy can supply essential information on carotenogenesis useful for molecular investigations on gene expression and regulation.     

Expression in Escherichia coli and properties of the carotene ketolase from Haematococcus pluvialis

Abstract High level expression of the functional β-carotene ketolase gene bkt from Haematococcus pluvialis occurred in Escherichia coli transformants producing β-carotene or zeaxanthin as a result of the presence of additional carotenoid genes from Erwinia uredovora . Requirement of molecular oxygen for the insertion of the keto group was demonstrated. The final product of this two-step ketolase reaction from β-carotene is canthaxanthin (4,4'-diketo-β-carotene) with the 4-monoketo derivative echinenone as an intermediate. A reaction sequence for the formation of astaxanthin from β-carotene was established based on kinetic data on astaxanthin formation in E. coli transformants carrying the hydroxylase gene crtZ from Erwinia along with bkt . We conclude that the carotenoids zeaxanthin and adonixanthin which accumulate in addition to astaxanthin in this transformant are products of side reactions rather than direct precursors of astaxanthin. The possible mechanisms for the formation of the keto derivatives are discussed.     

Low growth temperature-induced changes to pigment composition and photosynthesis in Zea mays genotypes differing in chilling sensitivity

The effects on pigment composition and photosynthesis of low temperature during growth were examined in the third leaf of three chilling-tolerant and three chilling-sensitive genotypes of Zea mays L. The plants were grown under a controlled environment at 24 or 14 °C at a photon flux density (PFD) of 200 or 600 μ mol m^–2 s^–1. At 24 °C, the two classes of genotypes showed little differences in their photosynthetic activity and their composition of pigments. At 14 °C, photosynthetic activity was considerably reduced but the chilling-tolerant genotypes displayed higher photosynthetic rates than the chilling-sensitive ones. Plants grown at 14 °C showed a reduced chlorophyll (Chl) a + b content and a reduced Chl a / b ratio but an increased ratio of total carotenoids to Chl a + b . These changes in pigment composition in plants grown at low temperature were generally more pronounced in the chilling-sensitive genotypes than in the tolerant ones, particularly at high PFD. Furthermore, at 14 °C, all the genotypes showed increased ratios of lutein, neoxanthin and xanthophyll-cycle carotenoids to Chl a + b but a reduced ratio of β -carotene to Chl a + b , especially at high PFD. At 14 °C, the chilling-tolerant genotypes, when compared with the sensitive ones, were characterized by higher contents of β -carotene and neoxanthin, a lower content of xanthophyll-cycle carotenoids, a lower ratio of xanthophylls to β -carotene, and less of their xanthophyll-cycle carotenoid pool in the form of zeaxanthin. These differences between the two classes of genotypes were more pronounced at high PFD than at low PFD. The results are discussed in terms of the relationship that may exist in maize between pigment composition and the capacity to form an efficient photosynthetic apparatus at low growth temperature.     

Note: Antioxidant properties of lipid fractions from Deinococcus radiophilus strain UWO1055

Lipids of the radio-resistant bacterium Deinococcus radiophilus were tested for their antioxidant properties. The crude lipid extract showed a significant antioxidant effect in linoleic acid emulsion. The crude extract was separated to polar and non-polar lipid fractions. The non-polar fraction showed an antioxidant effect in both suspensions and emulsions of linoleic acid, and inhibition of oxidation in a β-carotene emulsion. Lipids of the non-polar fraction were separated and their antioxidant activity was determined in a β-carotene emulsion; the lipid that was marked NP9 showed the highest antioxidant effect. Lipid NP9 inhibited oxidation in a β-carotene emulsion in the concentration range of 5–51 ppm. It is suggested that the antioxidant activity of lipids of D. radiophilus contribute to its radio-resistance.     

Frost hardiness development in Pinus silvestris seedlings in response to fertilization

The effects of different levels of nitrogen on freezing survival, the amounts of chlorophylls and β-carotene, the ratios Chl a/Chl b, and (Chl a + Chl b)/β-carotene in hardened and unhardened seedlings of Scots Pine (Pinus silvestris L.) have been investigated. There was. no correlation between frost hardiness and nitrogen content in the unhardened seedlings. However, the hardy seedlings with the highest nitrogen content, showed a decrease in frost hardiness of 3°C. The amounts of chlorophylls and β-carotene increased for all the treatments during hardening, except for the seedlings that had the highest nitrogen content; so that the effect of fertilizer was more evident in non-hardened than in hardened plants. The ratios Chl a/Chl b decreased during hardening in all the treatments. This was an effect of a larger increase of Chl b than Chl a. The ratios of Chl a + Chl b/β-carotene also decreased during hardening except for the plants that were fertilized with the second lowest amount of nitrogen. Since the amounts of Chl a and Chl b increase during hardening the amount of β-carotene increases even more.
The growth rates of the seedlings were closely related to the nitrogen content for the different treatments. All plants were infected with ectotrophic mycorrhizae, which resulted in an enhancement of ion transportation from the soil to the plants. This is important when the supply of ions is low.     

Changes in carotenoids but not in D1 protein in response to nitrogen depletion and recovery in a cyanobacterium

Abstract In Synechococcus PCC 6301 ( Anacystis nidulans ) the imposition of nitrogen stress resulted in substantial losses of phycobiliproteins, lesser changes in chlorophyll-proteins and a dramatic change in carotenoid composition. In nitrogen-depleted cultures carotenoids continued to be synthesised, with the increase being accounted for by zeaxanthin with β-carotene content declining slightly. In these cultures zeaxanthin accounted for 75% of the carotenoid present compared to 43% in nitrogen-replete cells. Amounts of D1, a protein associated with the Photosystem II reaction centre, were similar in nitrogen-replete and nitrogen-starved cells; this retention was in accord with those of β-carotene and chlorophyll. On nitrate replenishment, zeaxanthin was not produced for 36 h, by which time β-carotene level had increased to restore the carotenoid composition characteristic of an exponential culture, and normal phycocyanin and chlorophyll levels had also been recovered. Throughout, the ratio of β-carotene to chlorophyll remained more-or-less constant.     

Functional analysis of multiple carotenogenic genes from <Emphasis Type="Italic">Lycium barbarum</Emphasis> and <Emphasis Type="Italic">Gentiana lutea</Emphasis> L. for their effects on β-carotene production in transgenic tobacco

Carotenoids are red, yellow and orange pigments, which are widely distributed in nature and are especially abundant in yellow-orange fruits and vegetables and dark green leafy vegetables. Carotenoids are essential for photosynthesis and photoprotection in plant life and also have different beneficial effects in humans and animals (van den Berg et al. 2000). For example, β-carotene plays an essential role as the main dietary source of vitamin A. To obtain further insight into β-carotene biosynthesis in two important economic plant species, Lycium barbarum and Gentiana lutea L., and to investigate and prioritize potential genetic engineering targets in the pathway, the effects of five carotenogenic genes from these two species, encoding proteins including geranylgeranyl diphosphate synthase, phytoene synthase and δ-carotene desaturase gene, lycopene β-cyclase, lycopene ε-cyclase were functionally analyzed in transgenic tobacco (Nicotiana tabacum) plants. All transgenic tobacco plants constitutively expressing these genes showed enhanced β-carotene contents in their leaves and flowers to different extents. The addictive effects of co-ordinate expression of double transgenes have also been investigated.     

Qualitative and quantitative composition of pigments in Phaeodactylum tricornutum (Bacillariophyceae) stressed by iron

The effect of Fe(III) deficiency on qualitative and quantitative changes in pigment composition in Phaeodactylum tricornutum Bohlin was demonstrated by HPLC and AAS. Maximum content of pigments showed the diatom cells incubated at the optimum iron concentration, i.e., 10 M. The contents of chlorophyll a, chlorophyll c ₁+c ₂, fucoxanthin, diadinoxanthin and ,-carotene were 109.99, 20.16, 40.39, 1.29 and 1.48 fg per cell, respectively. The results obtained showed that Fe(III) affected qualitative and quantitative pigment composition in P. tricornutum. The content of individual pigments, proportions between accompanying pigments and their ratios to chlorophyll a were important indicators of phytoplankton response to iron stress. The strong reduction in ,-carotene content, several times (2–5) increase in diadinoxanthin level as compared to ,-carotene, and high amount of diadinoxanthin in relation to chlorophyll a were observed in algae growing at very low Fe(III) concentrations, 0.001 and 0.01 M. The data suggested that phytoplankton pigments could be a potential physiological marker.     

The effect of veratrole on carotenoid biosynthesis by Phycomyces blakesleeanus

A number of chemical compounds are known to affect the biosynthetic pathways of β-carotene. Both site-specific inhibitors as well as general stimulators of carotenogenesis have been described. It has been reported that veratrole enhances β-carotene synthesis when applied to agar cultures of Phycomyces blakesleeanus but we found no significant stimulation of β-carotene production in submerged culture. Moreover, veratrole in high concentrations (> 0.1% w/v), unlike diphenylamine, inhibits the formation of phytoene, resulting in an almost total block of carotenoid biosynthesis.