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Microalgal Pigments as Natural Color
Published in Hafiz Ansar Rasul Suleria, Megh R. Goyal, Masood Sadiq Butt, Phytochemicals from Medicinal Plants, 2019
K. G. Sreekala, Malairaj Sathuvan, Javee Anand, Karuppan Ramamoorthy, Vengatesh Babu, S. Nagaraj
Recently, there has been growing demand for fucoxanthin obtained from brown algae and diatoms. Reports indicate its potential to prevent cell growth and initiate apoptosis in human tumor cells, and antioxidant, anti-inflammatory, antidiabetic, and anti-obesity properties.2Chaetoceros calcitrans, a representative marine species from the class Bacillariophyceae, accounts for the base of marine food chain. The major light harvesting complexes in this diatom is fucoxanthin, which makes up to the major part of the total production of carotenoids in nature. Previous studies revealed fucoxanthin to be an effective free radical scavenger that enhances the expression of HO-1 and NQO-1 in the cells.15
Vitamin, Mineral, Antioxidant, and Herbal Supplements: Facts and Fictions
Published in José León-Carrión, Margaret J. Giannini, Behavioral Neurology in the Elderly, 2001
The carotenoids protective against macular degeneration appear to be lutein and its isomer, both normally present in high concentrations in the macula. It was recently discovered2 that proteins associated with 3-carotenoids are light-harvesting complexes (LHCs), which capture light for photosynthesis in higher plants. One wonders if there is a similar carotenoid-dependent LHC in the human retina, which needs lycopene and zeaxanthin.
General and Practical Aspects of Membrane Protein Crystallization
Published in Hartmut Michel, Crystallization of Membrane Proteins, 1991
With most other membrane protein crystals the situation is different. In the case of bacteriorhodopsin, the reaction center from Rb. sphaeroides, several light-harvesting complexes from photosynthetic bacteria, and porin from E. coli with the same precipitating agent and under the same conditions of ionic strength, pH, and temperature, the same crystal form is obtained when a slightly different detergent is used. These observations probably indicate that protein-protein interactions are the dominant driving forces for the crystallization of these proteins.
Detrimental effect of UV-B radiation on growth, photosynthetic pigments, metabolites and ultrastructure of some cyanobacteria and freshwater chlorophyta
Published in International Journal of Radiation Biology, 2021
Mostafa M. El-Sheekh, Eman A. Alwaleed, Aml Ibrahim, Hani Saber
The detrimental impact of UV-B on photosynthetic pigments could be attributed to bleaching by influence of UV-B or by way of active oxygen mediated peroxidation (Tyagi et al. 1992; El-Sheekh et al. 2010). In our previous work regarding the effect of UV-B on lipid peroxidation level measured as malondialdehyde contents and antioxidant enzymes in the freshwater microalgae, P. cryptovaginata, N. carneum, S. acutus, M. aeruginosa and marine Microcystis we reported that the higher exposure periods of UV-B exerted inhibitory effect on the biosynthesis of MDA contents. Similar effect was reported in the antioxidant enzymes activity of some investigated microalgae based on exposure period and algal species (Saber et al. 2020). Reduction in chlorophyll contents under UV-B stress recorded in this study could be caused by the damage of photosystem II (PS II), and their influence on structure and composition of light-harvesting complex result in disruption of chloroplast structure (El-Shintinawy 2000; Vani et al. 2001; El-Sheekh et al. 2010). Also, the reduction in pigment content by UV radiation may be due to decreased production of the main chlorophyll pigmet complexes encoded by cap gene family (Jordan et al. 1991, 1994). UV radiation can destroy phycobiliproteins pigments in cyanobacteria, which harvesting the photosynthetically active light (Sinha et al. 1995; Pandey et al. 1997). In addition, reduction in photosynthetic activity by UV radiation may be caused by degradation of main components like D1 protein of PSII (Vass 1997) or Rubisco enzyme (Bischof et al. 2000), damage the photosynthetic apparatus (Bischof et al. 2000; Lütz et al. 2005), or a result of decreased genes expression participated in photosynthesis (Mackerness et al. 1999). Döhler and Lohmann (1995) reported that the destruction of the pigments depends on UV wavebands and exposure time.
Separating toxicity and shading in algal growth inhibition tests of nanomaterials and colored substances
Published in Nanotoxicology, 2022
Lars Michael Skjolding, Sara Nørgaard Sørensen, Karen Scharling Dyhr, Rune Hjorth, Louise Schlüter, Camilla Hedberg, Nanna B. Hartmann, Philipp Mayer, Anders Baun
The freshwater green alga Raphidocelis subcapitata belongs to the class Chlorophyceae, which has pigments similar to those found in higher plants, including chlorophylls, α- and β-carotene, lutein, neoxanthin, violaxanthin, antheraxanthin and zeaxanthin (Young 1993). Changes in the cellular composition of the pigments as a function of light intensity were clearly demonstrated in experiments using neutral-density filters (Figure 2(A)). Decreasing light intensity resulted in a decrease in photo-protective pigments such as astaxanthin, antheraxanthin, and zeaxanthin. The decrease in cellular content of astaxanthin, antheraxanthin and zeaxanthin with decreasing light intensity corresponds with their photo-protective function, as described in literature (Dubinsky and Stambler 2009; Niyogi et al. 1997) (Figure 2(A)). Oppositely, the content of the light harvesting pigments chlorophyll a and b, lutein, neoxanthin, and α- and β-carotene generally increased with decreasing light intensity, although for some of these pigments the content level off at the highest shading level, implying a physical limit for the up-regulation mechanism (Figure 2(A)). It should be noted that pigments such as zeaxanthin, violaxanthin and antheraxanthin are structural components of both light harvesting complexes and photo-protective complexes (units for absorption of excess light energy). Thus, direct interpretation of increases or decreases as function of light availability should be done in connection with the regulation of other pigments to avoid misinterpretation. Similar trends of increasing light harvesting pigments as a function of decreasing light has also been found in other species of chlorophytes e.g. Chlorella sp. and Brachiomonas submarina (Schlüter et al. 2000) as well as Sphaerocystis schroeteri, Stichococcus sp., Mougeotia sp. and Botryococcus braunii (Lauridsen et al. 2011).
Cellular biogenesis of metal nanoparticles by water velvet (Azolla pinnata): different fates of the uptake Fe3+ and Ni2+ to transform into nanoparticles
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2021
Ratima Janthima, Sineenat Siri
The responses of A. pinnata to the metal treatments could be determined by the changed profiles of functional groups of the plant biomolecules as determined by ATR-FTIR analysis. Figure 4 shows the ATR-FTIR spectra of the roots of A. pinnata exposed to Fe(NO3)3 and Ni(NO3)2. In Fe(NO3)3 and Ni(NO3)2 treated plants, FTIR spectra revealed the changes in peak intensity and new emergent peak as compared with the control plants. Six spectral peaks were modulated in response to these metal treatments, which were in the ranges of 3342−3329, 1632−1616, 1556−1539, 1384−1373, 1057−1053, and 672 cm−1. These spectral peaks corresponded to O–H stretching vibration of alcohol [30], N–H bending vibration of primary amine [30], N–H bending vibration of secondary amide [31], symmetric COO– stretching of carbonyl group [30], C–O stretching vibration of primary alcohol [32], and M–O bond vibration [33], respectively. In the treated plants, two reduction peaks at 3342−3329 and 1057−1053 cm−1 (O–H and C–O of primary alcohol) suggested the possible reduction of some carbohydrates in response to Fe and Ni treatments. The reduction of starch synthesis was reported as one of the metal stress effects in plants. In metal-treated plants, a lower photosynthesis was detected, resulting from metal-induced disruption of light harvesting complex II, the basic pigment-protein complex in photosystem II, and reduction of chlorophyll contents [34]. In contrast, the increased peak intensity at 1384−1373 cm−1 (COO– stretching of carbonyl group) suggested a possible induction of some carbohydrates under a metal stress condition. The inductions of pectin and antioxidant sugars were reported in metal-stress plants. Pectin production was induced to capture and prevent metal translocation into the cells [35]. Increased levels of antioxidant sugars were significant in plants to cope with metal toxicity effects by scavenging reactive oxygen species (ROS) [36]. In addition to carbohydrates, there was a possible reduction of some proteins in metal-treated plants as indicated by the reduced peak intensity at 1632−1616 cm−1 (N–H of primary amine). There was a report of metal stress effects on a protein folding process, resulting in misfolded and non-functioned proteins. These proteins were subsequently degraded through a ubiquitin-proteasome process or autophagy, resulting in reducing levels of some proteins in metal-stress plants [37]. In contrast, there were also possibly newly synthesized proteins in response to metal stress, suggesting new emergent peak at 1556−1539 cm−1 (N–H of secondary amide). The newly synthesized proteins might be related to the metal detoxification processes, such as phytochelatins, metallothionines, and antioxidant enzymes [38]. Another emergent peak was detected at 672 cm−1 (M–O bonding), indicating the formation of metal-oxygen bonding occurring in the metal-treated plants.