China
Africa
Explore chapters and articles related to this topic
Inter- and Intracellular Signaling in Plant Cells with Participation of Neurotransmitters (Biomediators)
Published in Akula Ramakrishna, Victoria V. Roshchina, Neurotransmitters in Plants, 2018
Cholinesterase activity of organelles may be a marker of the presence of acetylcholine and its participation in the information transfer and regulation the reactions occur within the cellular compartments. The cholinesterase activity is located within the cell too—as has been shown first in root cell cytoplasm and plasmalemma of Phaseolus aureus (Fluck and Jaffe 1974c, 1976), nucleus of P. sativum (Maheshwary et al. 1982), and chloroplasts (Roshchina and Mukhin 1984, 1986, 1987; Gorska-Brylass et al. 1990; Gorska-Brylass and Smolinski 1992). Perhaps, the contacts between organelles include the enzyme. When the hydrolysis of acetylcholine by the chloroplasts of pea P. sativum and common nettle U. dioica was analyzed (Roshchina and Mukhin 1984, 1987a), it has been shown that the highest hydrolyzing activity is concentrated in chloroplasts and is inhibited by specific inhibitors of animal cholinesterases neostigmine and physostigmine. The cholinesterase activity has been found in fractions of outer membranes and thylakoids (Roshchina 1989). Moreover, the activity of the enzyme in thylakoids was approximately seven-fold higher than in chloroplast envelope. The concentration curves of the rate of hydrolysis of cholinic esters in a dependence on substrate show that the chloroplast cholinesterase hydrolyzes acetylcholine with a higher rate than butyrylcholine, and the excess of substrate to depress the cholinesterase activity (Roshchina and Mukhin 1984).
Isolation of Chloroplasts for the Study of Oxygen Radical Reactions
Published in Robert A. Greenwald, CRC Handbook of Methods for Oxygen Radical Research, 2018
In the green leaves of higher plants, the process of photosynthesis occurs within chloroplasts. Under the electron microscope, these organelles have an outer envelope consisting of two membranes. The envelope encloses the stroma of the chloroplast, in which floats a complex internal membrane structure with distinct features: regions of closely-stacked membranes (grana) interconnected by a three-dimensional network of membranes (the stroma thylakoids). The grana were, until recently, regarded as being made up of piles of essentially separate discs (thylakoids) interconnected by stroma thylakoids, but in fact, the network of interconnections is so extensive that the internal spaces of both granal and stromal thylakoids are all effectively in contact with each other.
Carotenoids
Published in Ruth G. Alscher, John L. Hess, Antioxidants in Higher Plants, 2017
Kenneth E. Pallett, Andrew J. Young
The bulk of the chloroplast carotenoids are associated with the light-harvesting complexes in the thylakoid membrane. The carotenoids present in these antenna complexes, the bulk of which are mainly xanthophylls, have the ability to absorb light in the wavelength range of 400 to 500 nm. Energy is transferred from the carotenoid-excited singlet state (1Car*) to S0 chlorophyll (1Chi) by singlet-singlet energy transfer (Reactions 1 to 3). This energy-transfer process is generally recognized to proceed with very high efficiency, itself suggesting a close proximity of carotenoid and chlorophyll molecules. In vitro studies using synthetic caroteno-porphyrin molecules have shown that high efficiencies can be achieved provided that a precise structural arrangement is maintained between the carotenoid and chlorophyll molecules.37 The possible role of carotenoid radical species in electron transfer processes in light harvesting has been discussed for a number of years, although there is still a lack of clear evidence for their involvement in anything but artificial systems.33
Algal extracellular polymeric substances (algal-EPS) for mitigating the combined toxic effects of polystyrene nanoplastics and nano-TiO2 in Chlorella sp.
Published in Nanotoxicology, 2023
Lokeshwari Natarajan, M. Annie Jenifer, Willie J. G. M. Peijnenburg, Amitava Mukherjee
The results of the photosynthetic efficiency tests demonstrate that mixtures of NMs have an adverse effect on PS II light energy transfer. The increase in ROS concentrations upon NM treatment may disrupt the integrity of thylakoids and impede photosynthesis. Since microalgal EPS can help in scavenging free radicals, it is reasonable to hypothesize that the presence of algal EPS contributed to a general mitigation of oxidative stress, eventually decreasing adverse effects on photosynthetic parameters in the algae. In general, these results demonstrated two processes: the adsorption of biomolecules leading to EPS-NMs complexes, and the formation of NM aggregates induced by the chemistry of the medium. The aggregation-related reduced bioavailability and the free radical scavenging effect together has helped to reduce the toxicity of EPS-NMs. The outcome of these processes depends on the [EPS]:[NMs] ratio in the suspension (Surette and Nason 2019).
Use of an immobilised thermostable α-CA (SspCA) for enhancing the metabolic efficiency of the freshwater green microalga Chlorella sorokiniana
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2020
Giovanna Salbitani, Sonia Del Prete, Francesco Bolinesi, Olga Mangoni, Viviana De Luca, Vincenzo Carginale, William A. Donald, Claudiu T. Supuran, Simona Carfagna, Clemente Capasso
The analysis of the genome belonging to different microalgal species evidences a very variegated pattern of CA classes. It is possible to identify seven of the eight CA-classes discovered up to now in these organisms. The different classes can coexist or have different localizations inside the cells, such as the cell wall, plasma membrane, cytosol, mitochondria, chloroplast stroma, and chloroplast thylakoid lumen73–75. Besides, for each enzyme class, many isoforms were reported to exist74. In the present manuscript, the interest was focussed on the freshwater green microalga Chlorella sorokiniana as it can be useful in many fields, such as photosynthesis research, pharmaceuticals for humans, aquaculture foods, and wastewater treatment. In 1998, a soluble form of CA belonging to the α-class76 was purified and characterised from C. sorokiniana. Other CA-classes appear to be encoded by this green microalga genome although they have not yet been characterised76.
Mechanism of long-term toxicity of CuO NPs to microalgae
Published in Nanotoxicology, 2018
Xingkai Che, Ruirui Ding, Yuting Li, Zishan Zhang, Huiyuan Gao, Wei Wang
The PsbO protein is the core protein of OEC and was detected with thylakoid membranes of the treated algae by Western blot. For thylakoid membranes preparation, 50mL algae medium was centrifugated (8000rpm, 5min) and then the supernatants were removed. The remaining algal pellet was homogenized in an ice-cold isolation buffer (100mM sucrose, 50mM HEPES, pH 7.8, 20mM NaCl, 2mM EDTA, and 2mM MgCl2) and filtered through three layers of pledget. The filtrate was centrifuged at 3000g for 10min. The sediments were washed with isolation buffer, re-centrifuged, and finally suspended in an isolation buffer. The thylakoid membrane proteins were then denatured and separated using 12% polyacrylamide gradient gel. The denatured protein complexes in the gel were then electro-blotted to PVDF membranes, probed with PsbO antibody, and visualized by the enhanced chemi-luminescence method.