The Experts below are selected from a list of 306 Experts worldwide ranked by ideXlab platform
Pooja Singh - One of the best experts on this subject based on the ideXlab platform.
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relative phytotoxicity of hydroquinone on rice oryza sativa l and associated aquatic weed green musk Chara Chara zeylanica willd
Pesticide Biochemistry and Physiology, 2005Co-Authors: D.k. Pandey, Neeraj Mishra, Pooja SinghAbstract:Abstract Relative toxicity of hydroquinone on rice (Oryza sativa L. var. Kranti) and associated submerged aquatic weed green musk Chara (Chara zeylanica Willd.) was investigated for exploring possible use of the phytotoxin as herbicide in management of the weed. The hydroquinone was lethal to rice at and above 5 mM. It was phytotoxic to green musk Chara at as low as 0.01 mM and lethal at 0.075–0.10 mM. The toxicity symptoms on the weed were dull green appearance followed by loss of biomass, and bleaching and fragmentation of the plant resulting in death in 3–12 days. The treated plants showed an excessive leakage of cellular constituents reflecting loss of cellular membrane integrity. There was a loss of metabolites like starch, sugars, amino acids, phenolics, protein, phosphorus, potassium, and chlorophyll a, chlorophyll b, total chlorophyll, and carotenoid pigments with the advancement of the treatment and concomitant accumulation of oxidative stress as reflected by initial spurt of activity of some of the enzymes of the oxidative stress. Relatively higher toxicity of hydroquinone, a phytotoxin, to green musk Chara than to rice appeared to be due to capability of the latter to withstand excessive accumulation of the chemical in the roots and inability of the chemical to reach the shoots. The phytotoxin appears to have killed the weed by causing massive damage to cellular membrane integrity, loss of metabolic activities and macromolecules, accompanied by associated starvation and accumulation of oxidative stress. Such a differential toxicity of a phytotoxin, which is short lived in the environment, to a crop and associated weed may have potential of weed management under certain circumstances.
D.k. Pandey - One of the best experts on this subject based on the ideXlab platform.
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relative phytotoxicity of hydroquinone on rice oryza sativa l and associated aquatic weed green musk Chara Chara zeylanica willd
Pesticide Biochemistry and Physiology, 2005Co-Authors: D.k. Pandey, Neeraj Mishra, Pooja SinghAbstract:Abstract Relative toxicity of hydroquinone on rice (Oryza sativa L. var. Kranti) and associated submerged aquatic weed green musk Chara (Chara zeylanica Willd.) was investigated for exploring possible use of the phytotoxin as herbicide in management of the weed. The hydroquinone was lethal to rice at and above 5 mM. It was phytotoxic to green musk Chara at as low as 0.01 mM and lethal at 0.075–0.10 mM. The toxicity symptoms on the weed were dull green appearance followed by loss of biomass, and bleaching and fragmentation of the plant resulting in death in 3–12 days. The treated plants showed an excessive leakage of cellular constituents reflecting loss of cellular membrane integrity. There was a loss of metabolites like starch, sugars, amino acids, phenolics, protein, phosphorus, potassium, and chlorophyll a, chlorophyll b, total chlorophyll, and carotenoid pigments with the advancement of the treatment and concomitant accumulation of oxidative stress as reflected by initial spurt of activity of some of the enzymes of the oxidative stress. Relatively higher toxicity of hydroquinone, a phytotoxin, to green musk Chara than to rice appeared to be due to capability of the latter to withstand excessive accumulation of the chemical in the roots and inability of the chemical to reach the shoots. The phytotoxin appears to have killed the weed by causing massive damage to cellular membrane integrity, loss of metabolic activities and macromolecules, accompanied by associated starvation and accumulation of oxidative stress. Such a differential toxicity of a phytotoxin, which is short lived in the environment, to a crop and associated weed may have potential of weed management under certain circumstances.
P. Perumal - One of the best experts on this subject based on the ideXlab platform.
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Anatomical Studies on the sperm storage organ of Pati and Chara-Chemballi Ducks
Indian Journal of Animal Research, 2017Co-Authors: A. Deka, K. Sarma, S. Sarma, J. Goswami, J. D. Mahanta, M. Talukdar, J. Rajkhowa, P. PerumalAbstract:The present investigation was conducted on the comparative anatomical study of vagina (sperm storage organ) of Pati and Chara-Chemballi ducks during laying periods. The vagina was collected immediately after death and anatomical studies were made on it. The vagina was a narrow muscular tube, sharply curved and was tightly bound by ligament. The length, width thickness and weight of vagina of Chara-Chemballi ducks were significantly (p>0.01) higher than Pati duck. The lining epithelium consisted of pseudostratified columnar epithelial cells with few goblet cells. The mean height of lamina epithelialis mucosae of vagina of the present study was significantly (p>0.01) higher in Chara-Chemballi duck (26.508±0.298 µm) than Pati duck (23.058±0.330 µm). A weak PAS positive reaction was noticed in the lining epithelium of vagina of Pati and Chara-Chembali ducks.
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Anatomical Studies on the sperm storage organ of Pati and Chara-Chemballi Ducks
Indian Journal of Animal Research, 2017Co-Authors: A. Deka, S. Sarma, J. Goswami, J. D. Mahanta, M. Talukdar, J. Rajkhowa, Kushal Konwar Sarma, P. PerumalAbstract:The present investigation was conducted on the comparative anatomical study of vagina (sperm storage organ) of Pati and Chara-Chemballi ducks during laying periods. The vagina was collected immediately after death and anatomical studies were made on it. The vagina was a narrow muscular tube, sharply curved and was tightly bound by ligament. The length, width thickness and weight of vagina of Chara-Chemballi ducks were significantly (p
Keiichi Yamamoto - One of the best experts on this subject based on the ideXlab platform.
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unique charge distribution in surface loops confers high velocity on the fast motor protein Chara myosin
Proceedings of the National Academy of Sciences of the United States of America, 2009Co-Authors: Kohji Ito, Yukie Yamaguchi, Kenji Yanase, Yousuke Ichikawa, Keiichi YamamotoAbstract:Most myosins have a positively charged loop 2 with a cluster of lysine residues that bind to the negatively charged N-terminal segment of actin. However, the net charge of loop 2 of very fast Chara myosin is zero and there is no lysine cluster in it. In contrast, Chara myosin has a highly positively charged loop 3. To elucidate the role of these unique surface loops of Chara myosin in its high velocity and high actin-activated ATPase activity, we have undertaken mutational analysis using recombinant Chara myosin motor domain. It was found that net positive charge in loop 3 affected V(max) and K(app) of actin activated ATPase activity, while it affected the velocity only slightly. The net positive charge in loop 2 affected K(app) and the velocity, although it did not affect V(max). Our results suggested that Chara myosin has evolved to have highly positively charged loop 3 for its high ATPase activity and have less positively charged loop 2 for its high velocity. Since high positive charge in loop 3 and low positive charge in loop 2 seem to be one of the reasons for Chara myosin's high velocity, we manipulated charge contents in loops 2 and 3 of Dictyostelium myosin (class II). Removing positive charge from loop 2 and adding positive charge to loop 3 of Dictyostelium myosin made its velocity higher than that of the wild type, suggesting that the charge strategy in loops 2 and 3 is widely applicable.
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Binding of Chara Myosin globular tail domain to phospholipid vesicles.
Plant & cell physiology, 2007Co-Authors: Shun-ya Nunokawa, Taku Kashiyama, You Hachikubo, Kohji Ito, Kiyo Shimada, Hiromi Anan, Keiichi YamamotoAbstract:Binding of Chara myosin globular tail domain to phospholipid vesicles was investigated quantitatively. It was found that the globular tail domain binds to vesicles made from acidic phospholipids but not to those made from neutral phospholipids. This binding was weakened at high KCl concentration, suggesting that the binding is electrostatic by nature. The dissociation constant for the binding of the globular tail domain to 20% phosphatidylserine vesicles (similar to endoplasmic reticulum in acidic phospholipid contents) at 150 mM KCl was 273 nM. The free energy change due to this binding calculated from the dissociation constant was -37.3 kJ mol(-1). Thus the bond between the globular tail domain and membrane phospholipids would not be broken when the motor domain of Chara myosin moves along the actin filament using the energy of ATP hydrolysis (DeltaG degrees ' = -30.5 kJ mol(-1)). Our results suggested that direct binding of Chara myosin to the endoplasmic reticulum membrane through the globular tail domain could work satisfactorily in Chara cytoplasmic streaming. We also suggest a possible regulatory mechanism of cytoplasmic streaming including phosphorylation-dependent dissociation of the globular tail domain from the endoplasmic reticulum membrane.
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kinetic mechanism of the fastest motor protein Chara myosin
Journal of Biological Chemistry, 2007Co-Authors: Kohji Ito, Taku Kashiyama, Mitsuo Ikebe, Toshifumi Mogami, Takahide Kon, Keiichi YamamotoAbstract:Chara corallina class XI myosin is by far the fastest molecular motor. To investigate the molecular mechanism of this fast movement, we performed a kinetic analysis of a recombinant motor domain of Chara myosin. We estimated the time spent in the strongly bound state with actin by measuring rate constants of ADP dissociation from actin.motor domain complex and ATP-induced dissociation of the motor domain from actin. The rate constant of ADP dissociation from acto-motor domain was >2800 s(-1), and the rate constant of ATP-induced dissociation of the motor domain from actin at physiological ATP concentration was 2200 s(-1). From these data, the time spent in the strongly bound state with actin was estimated to be <0.82 ms. This value is the shortest among known values for various myosins and yields the duty ratio of <0.3 with a V(max) value of the actin-activated ATPase activity of 390 s(-1). The addition of the long neck domain of myosin Va to the Chara motor domain largely increased the velocity of the motility without increasing the ATP hydrolysis cycle rate, consistent with the swinging lever model. In addition, this study reveals some striking kinetic features of Chara myosin that are suited for the fast movement: a dramatic acceleration of ADP release by actin (1000-fold) and extremely fast ATP binding rate.
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Chara Myosin and the Energy of Cytoplasmic Streaming
Plant & cell physiology, 2006Co-Authors: Keiichi Yamamoto, Kiyo Shimada, Khoji Ito, Saeko Hamada, Akio Ishijima, Takayoshi Tsuchiya, Masashi TazawaAbstract:Recently, it was found that myosin generating very fast cytoplasmic streaming in Chara corallina has very high ATPase activity. To estimate the energy consumed by this myosin, its concentration in the internodal cells of C. corallina was determined by quantitative immunoblot. It was found that the concentration of Chara myosin was considerably high (200 nM) and the amount of ATP consumed by this myosin would exceed that supplied by dark respiration if all myosin molecules were fully activated by the interaction with actin. These results and model calculations suggested that the energy required to generate cytoplasmic streaming is very small and only one-hundredth of the existing myosin is enough to maintain the force for the streaming in the Chara cell.
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Importance of the converter region for the motility of myosin as revealed by the studies on chimeric Chara myosins.
Journal of molecular biology, 2004Co-Authors: Masaya Seki, Taku Kashiyama, You Hachikubo, Kohji Ito, Keiichi YamamotoAbstract:A long alpha-helix in myosin head constitutes a lever arm together with light chains. It is known from X-ray crystallographic studies that the first three turns of this lever arm alpha-helix are inserted into the converter region of myosin. We previously showed that chimeric Chara myosin in which the motor domain of Chara myosin was connected to the lever arm alpha-helix of Dictyostelium myosin had motility far less than that expected for the motor domain of Chara myosin. Here, we replaced the inserted three turns of alpha-helix of Dictyostelium myosin with that of the Chara myosin and found that the replacement enhanced the motility 2.6-fold without changing the ATPase activity so much. The result clearly showed the importance of interaction between the converter region and the lever arm alpha-helix for the efficient motility of myosin.
Marcela Bianchessida Cunha-santino - One of the best experts on this subject based on the ideXlab platform.
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Surfactant and temperature as forcing functions on the growth of Egeria densa and Chara sp.: a modeling approach
Environmental Science and Pollution Research, 2021Co-Authors: Emmanuelle Leite Wanderley, Irineu Bianchini, Marcela Bianchessida Cunha-santinoAbstract:The wide use of detergents combined with rising water temperature is currently issuing of environmental concern. To evaluate the effect of sodium dodecyl sulfate (SDS) and temperature on macrophyte and talophyte growth, bioassays were conducted with distinct SDS concentrations (0.5 and 8.0 mg L^−1) and temperatures (25 and 27 °C). The length of the Egeria densa and Chara sp. and the number and lengths of shoots were measured. Kinetic models were used to verify the temperature and SDS concentrations, as driving factors in the growth. The 2 °C increase in thermal condition interfered positively in both elongation and shoot development in the E. densa growth. For Chara sp., this tendency was not observed for the relative contribution of the shoots, but the number was higher at 25 °C. The higher concentrations of SDS (8.0 mg L^−1) reduced the shoots’ number and the relative contribution for Chara sp. and E. densa ; meanwhile, the decrease in the growth coefficient was observed only for E. densa at 25 °C. In the Chara sp. development, the SDS addition interfered negatively in the growth coefficient. The predicted response of growth models will bring comprehensive knowledge of macrophytes and talophyte metabolism, and the interaction between plant species and forcing functions in modeling approaches will assist in finding the key processes driving plant growth under specific stressors.