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Srinivasan C, Mohamed Jasim K, Sridhar R. Measurement of D-M model on competitiveness of 3PL in Indian automobile industry through partial least square (PLS) estimation. Journal of Statistics and Management Systems 2022. [DOI: 10.1080/09720510.2022.2052447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
Affiliation(s)
- C. Srinivasan
- Department of Commerce, B. S. Abdur Rahman Crescent Institute of Science and Technology, Chennai, India
| | - K. Mohamed Jasim
- VIT Business School, Vellore Institute of Technology, Vellore, Tamil Nadu, India
| | - R. Sridhar
- KMG College of Education, Gudiyatham, Vellore dt., Tamil Nadu, India
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Rajendran T, Rajagopal S, Srinivasan C, Balakrishnan G, Sivasubramanian VK, Ganesan M. Effect of Sodium Dodecyl Sulfate on the Photoinduced Electron Transfer Reactions of Ruthenium(II)–Polypyridine Complexes with Phenolate Ions. Russ J Phys Chem 2021. [DOI: 10.1134/s0036024421100216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Abstract
A number of extensions of the class preservation results in the Esary, Marshall and Proschan shock model have been investigated by various authors in recent years, most recently by Ghosh and Ebrahimi. In this note, generalizations are obtained using different methods for the IFR and NBUE cases when the shocking process is a regular continuous-time Markov process with stationary transition probabilites.
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Srinivasan C, Kurian GP, Mariappan R. A case of bronchiectasis needing lung isolation for cerebello pontine angle tumor excision: Anesthetic challenges. Saudi J Anaesth 2016; 10:359-61. [PMID: 27375400 PMCID: PMC4916829 DOI: 10.4103/1658-354x.174923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
The main goals of neuroanesthesia are the maintenance of adequate cerebral perfusion pressure, avoidance of hypercarbia, hypoxemia, and to provide better brain relaxation. Providing anesthesia for a patient with bronchiectasis needing lung isolation for craniotomy can be challenging. A 56-year-old male patient, case of right lung bronchiectasis with a right cerebello pontine angle tumor underwent excision in the left lateral position. Since he had severe bronchiectasis of the right lung, we had isolated the right lung using right-sided double lumen tube to avoid spillage. Intraoperative split lung test was performed to assess the right lung contribution on carbon dioxide (CO2) elimination and found that there was a significant contribution from the right lung. Hence, both lungs were ventilated to control CO2. The importance of lung isolation to prevent spillage and avoidance of one lung ventilation to control the arterial CO2 are highlighted in this case report. By providing a balanced anesthetic keeping both, the neurosurgical and thoracic concerns are important for better postoperative outcome.
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Affiliation(s)
- C Srinivasan
- Department of Anesthesia, Christian Medical College, Vellore, Tamil Nadu, India
| | - G P Kurian
- Department of Anesthesia, Christian Medical College, Vellore, Tamil Nadu, India
| | - R Mariappan
- Department of Anesthesia, Christian Medical College, Vellore, Tamil Nadu, India
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Srinivasan C. Estimation in a Galton-Watson process. ADV APPL PROBAB 2016. [DOI: 10.2307/1427139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Srinivasan C, Liu Z, Scorza R. Ectopic expression of class 1 KNOX genes induce adventitious shoot regeneration and alter growth and development of tobacco (Nicotiana tabacum L) and European plum (Prunus domestica L). Plant Cell Rep 2011; 30:655-64. [PMID: 21212958 DOI: 10.1007/s00299-010-0993-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2010] [Revised: 12/20/2010] [Accepted: 12/21/2010] [Indexed: 05/07/2023]
Abstract
Transgenic plants of tobacco (Nicotiana tabacum L) and European plum (Prunus domestica L) were produced by transforming with the apple class 1 KNOX genes (MdKN1 and MdKN2) or corn KNOX1 gene. Transgenic tobacco plants were regenerated in vitro from transformed leaf discs cultured in a medium lacking cytokinin. Ectopic expression of KNOX genes retarded shoot growth by suppressing elongation of internodes in transgenic tobacco plants. Expression of each of the three KNOX1 genes induced malformation and extensive lobbing in tobacco leaves. In situ regeneration of adventitious shoots was observed from leaves and roots of transgenic tobacco plants expressing each of the three KNOX genes. In vitro culture of leaf explants and internode sections excised from in vitro grown MdKN1 expressing tobacco shoots regenerated adventitious shoots on MS (Murashige and Skoog 1962) basal medium in the absence of exogenous cytokinin. Transgenic plum plants that expressed the MdKN2 or corn KNOX1 gene grew normally but MdKN1 caused a significant reduction in plant height, leaf shape and size and produced malformed curly leaves. A high frequency of adventitious shoot regeneration (96%) was observed in cultures of leaf explants excised from corn KNOX1-expressing transgenic plum shoots. In contrast to KNOX1-expressing tobacco, leaf and internode explants of corn KNOX1-expressing plum required synthetic cytokinin (thidiazuron) in the culture medium to induce adventitious shoot regeneration. The induction of high-frequency regeneration of adventitious shoots in vitro from leaves and stem internodal sections of plum through the ectopic expression of a KNOX1 gene is the first such report for a woody perennial fruit trees.
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Affiliation(s)
- C Srinivasan
- United States Department of Agriculture, Agricultural Research Service, Appalachian Fruit Research Station, 2217 Wiltshire Road, Kearneysville, WV 25430, USA.
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Srinivasan C, Dsouza TM, Boominathan K, Reddy CA. Demonstration of Laccase in the White Rot Basidiomycete Phanerochaete chrysosporium BKM-F1767. Appl Environ Microbiol 2010; 61:4274-7. [PMID: 16535182 PMCID: PMC1388647 DOI: 10.1128/aem.61.12.4274-4277.1995] [Citation(s) in RCA: 183] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
It has been widely reported that the white rot basidiomycete Phanerochaete chrysosporium, unlike most other white rot fungi, does not produce laccase, an enzyme implicated in lignin biodegradation. Our results showed that P. chrysosporium BKM-F1767 produces extracellular laccase in a defined culture medium containing cellulose (10 g/liter) and either 2.4 or 24 mM ammonium tartrate. Laccase activity was demonstrated in the concentrated extracellular culture fluids of this organism as determined by a laccase plate assay as well as a spectrophotometric assay with ABTS [2,2(prm1)-azinobis(3-ethylbenzathiazoline-6-sulfonic acid)] as the substrate. Laccase activity was observed even after addition of excess catalase to the extracellular culture fluid to destroy the endogenously produced hydrogen peroxide, indicating that the observed activity is not due to a peroxidase. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by activity staining with ABTS revealed the presence of a laccase band with an estimated M(infr) of 46,500.
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Gaitonde R, Bhan A, Premdas E, Sukanya R, Srinivasan C, Khanna R, Sarojini NB, Sadgopal M, Gupte M. Learning from Binayak Sen: doctors as advocates of the poor and marginalized. Natl Med J India 2009; 22:218-219. [PMID: 20128105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
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Chaudhury K, Mehrotra R, Srinivasan C. Detecting 3-D motion field from range image sequences. IEEE Trans Syst Man Cybern B Cybern 2008; 29:308-14. [PMID: 18252305 DOI: 10.1109/3477.752806] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
An algorithm for computing three-dimensional (3-D) velocity field and motion parameters from a range image sequence is presented. It is based on a new integral 3-D rigid motion invariant feature-the trace of a 3x3 "feature matrix" related to the moment of inertia tensor. This trace can be computed at every point of a moving surface and provides a quantitative measure of the local shape of the surface. Based on the feature's conservation along the trajectory of every moving point, a 3-D Flow Constraint Equation is formulated and solved for the velocity field. The robustness of the feature in presence of noise and discontinuity is analyzed.
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Affiliation(s)
- K Chaudhury
- Dept. of Adv. Dev., Adobe Syst. Inc., San Jose, CA
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Srinivasan C, Katare YK, Muthukumaran T, Panda AK. Effect of additives on encapsulation efficiency, stability and bioactivity of entrapped lysozyme from biodegradable polymer particles. J Microencapsul 2005; 22:127-38. [PMID: 16019899 DOI: 10.1080/02652040400026400] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Low encapsulation efficiency, incomplete and erratic release profiles are the most common features of controlled released protein delivery systems employing biodegradable polymers. In the present study, lysozyme as a model protein was encapsulated in biodegradable microspheres using solvent evaporation method and the effect of amphiphilic stabilizer, a basic salt and a lyoprotectant on microparticle formulation was evaluated. Incorporation rat serum albumin (RSA) in the internal aqueous phase during emulsion increased the encapsulation efficiency of lysozyme and maintained the bioactivity. Use of NaHCO3 improved the encapsulation efficiency of lysozyme from 15-94%, but at the cost of reduced in vitro release characteristics. Incorporation of both RSA and NaHCO3 improved the bioactivity of lysozyme and decreased burst release of the protein from the polymer particle, but reduced the encapsulation efficiency from 90-70%. Addition of sucrose in the internal aqueous phase lowered the encapsulation efficiency which was restored by its addition in the external aqueous phase. Maintenance of internal aqueous phase pH close to the iso-electric point of the protein and osmotic balance between the internal aqueous phase and the external aqueous phase during solvent evaporation method helped in better encapsulation of the protein drug. In vitro release of the lysozyme correlated with the effect of different excipients on entrapment in polymer matrix. Entrapment efficiency as high as 76%, low burst effect and high bioactivity of the entrapped lysozyme was observed from the polymer particles. Use of RSA, sucrose and NaHCO3 helped in a co-operative way towards the formulation of particles entrapping bioactive lysozyme.
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Affiliation(s)
- C Srinivasan
- National Institute of Immunolgy, Aruna Asaf Ali Marg, New Delhi, India
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Berhane I, Srinivasan C. Stability of Neural Networks for Slightly Perturbed Training Data Sets. COMMUN STAT-THEOR M 2004. [DOI: 10.1081/sta-200026629] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Chaudhury K, Mehrotra R, Srinivasan C. Detecting 3D flow. Proceedings of the 1994 IEEE International Conference on Robotics and Automation 2002. [DOI: 10.1109/robot.1994.351216] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/19/2023]
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Abstract
The LYS7 gene in Saccharomyces cerevisiae encodes a protein (yCCS) that delivers copper to the active site of copper-zinc superoxide dismutase (CuZn-SOD, a product of the SOD1 gene). In yeast lacking Lys7 (lys7Delta), the SOD1 polypeptide is present but inactive. Mutants lacking the SOD1 polypeptide (sod1Delta) and lys7Delta yeast show very similar phenotypes, namely poor growth in air and aerobic auxotrophies for lysine and methionine. Here, we demonstrate certain phenotypic differences between these strains: 1) lys7Delta cells are slightly less sensitive to paraquat than sod1Delta cells, 2) EPR-detectable or "free" iron is dramatically elevated in sod1Delta mutants but not in lys7Delta yeast, and 3) although sod1Delta mutants show increased sensitivity to extracellular zinc, the lys7Delta strain is as resistant as wild type. To restore the SOD catalytic activity but not the zinc-binding capability of the SOD1 polypeptide, we overexpressed Mn-SOD from Bacillus stearothermophilus in the cytoplasm of sod1Delta yeast. Paraquat resistance was restored to wild-type levels, but zinc was not. Conversely, expression of a mutant CuZn-SOD that binds zinc but has no SOD activity (H46C) restored zinc resistance but not paraquat resistance. Taken together, these results strongly suggest that CuZn-SOD, in addition to its antioxidant properties, plays a role in zinc homeostasis.
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Affiliation(s)
- J P Wei
- Molecular Biology Institute, the School of Medicine, and the Department of Chemistry and Biochemistry, UCLA, Los Angeles, California 90095, USA
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Srinivasan C. Mistaken identity? Dent Update 2001; 28:475. [PMID: 11806193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/17/2023]
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Minadeo N, Layden B, Amari LV, Thomas V, Radloff K, Srinivasan C, Hamm HE, de Freitas DM. Effect of Li+ upon the Mg2+-dependent activation of recombinant Gialpha1. Arch Biochem Biophys 2001; 388:7-12. [PMID: 11361143 DOI: 10.1006/abbi.2001.2282] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Although lithium salts have been used in the treatment and prophylaxis of manic-depressive or bipolar patients for 50 years, the mechanism of the pharmacologic action of Li+ is unknown. Based on activity studies of inhibitory and stimulatory guanine-binding (G) proteins in rat cortical membranes, it was proposed that Li+ inhibition of G-proteins may account for its pharmacologic action. We used the purified alpha subunit of the recombinant inhibitory G-protein, rGialpha1, and found that Li+ at therapeutic levels significantly inhibited the formation of the GDP.AlF4-.rGialpha1 complex. Because our studies were conducted with a purified, metal-reconstituted G-protein rather than with cell membrane suspensions, our Li+ inhibition results lend additional support to the G-protein hypothesis for Li+ action.
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Affiliation(s)
- N Minadeo
- Department of Chemistry, Loyola University at Chicago, Illinois 60626, USA
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Lalitha A, Pitchumani K, Srinivasan C. Induced diastereoselectivity in photodecarboxylation of 2-phenylpropionic acid in faujasite zeolites. Tetrahedron 2001. [DOI: 10.1016/s0040-4020(01)00377-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Srinivasan C, Williams WM, Nagasawa HT, Chen TS. Effects of 2(RS)-n-propylthiazolidine-4(R)-carboxylic acid on extrahepatic sulfhydryl levels in mice treated with acetaminophen. Biochem Pharmacol 2001; 61:925-31. [PMID: 11274980 DOI: 10.1016/s0006-2952(01)00539-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The cysteine (Cys) precursor 2(RS)-n-propylthiazolidine-4(R)-carboxylic acid (PTCA) has been shown to protect against acetaminophen (APAP)-induced hepatic GSH, GSSG, and Cys depletion and hepatic necrosis. The aim of this study was to determine the effects of PTCA on the concentrations of sulfhydryl compounds in extrahepatic tissues, including renal cortex, whole blood, and brain, in C57BL/6 mice treated with hepatotoxic doses of APAP. PTCA (1-5 mmol/kg, i.p.) was administered 30 min after the administration of APAP at a dose (800 mg/kg; 5.29 mmol/kg, i.p.) that depleted hepatic GSH and Cys at 4 hr by 95 and 86%, respectively. Tissue concentrations of GSH and Cys were determined by HPLC. At 4 hr following APAP administration, renal cortical GSH and Cys concentrations were decreased to 64 and 39%, respectively, of vehicle-treated control values, and blood concentrations were decreased to 87 and 30%, respectively, of vehicle controls. Brain GSH and Cys were not depleted by APAP. PTCA at 5 mmol/kg (i) attenuated the APAP-induced depletion of GSH and Cys at 4 hr in renal cortex (78 and 65%, respectively, of vehicle controls), (ii) prevented APAP-induced Cys depletion in blood (670% of vehicle controls) with no effect on GSH concentration (94% of vehicle controls), and (iii) increased GSH and Cys concentrations in brain (119 and 411%, respectively, of vehicle controls). The results demonstrate a high degree of tissue selectivity in the APAP-induced depletion of GSH and Cys, and in the effectiveness of PTCA in maintaining and even elevating sulfhydryl levels in extrahepatic tissues of APAP-treated mice.
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Affiliation(s)
- C Srinivasan
- Department of Pharmacology and Toxicology, University of Louisville, School of Medicine, Louisville, KY 40292, USA
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Srinivasan C, Williams WM, Ray MB, Chen TS. Prevention of acetaminophen-induced liver toxicity by 2(R,S)-n-propylthiazolidine-4(R)-carboxylic acid in mice. Biochem Pharmacol 2001; 61:245-52. [PMID: 11163339 DOI: 10.1016/s0006-2952(00)00558-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The cysteine (Cys) precursor 2(R,S)-n-propylthiazolidine-4(R)-carboxylic acid (PTCA) was shown previously to maintain near normal levels of hepatic GSH and GSSG at 24 hr and to protect against hepatic necrosis and mortality at 48 hr after toxic doses of acetaminophen (APAP) in mice. Studies were performed in C57BL/6 mice to determine: (a) the time course of APAP-induced hepatic sulfhydryl depletion, and (b) the effectiveness of PTCA in preventing APAP-induced decreases in sulfhydryl concentrations at the time of maximal depletion. APAP (400-800 mg/kg in 50% propylene glycol; 2.65-5.29 mmol/kg) and PTCA (1-5 mmol/kg 30 min after APAP) were administered i.p. Hepatic GSH, GSSG, and Cys concentrations were determined by HPLC. Hepatocellular damage was assessed by elevations in serum glutamate-pyruvate transaminase (SGPT) activity and histopathologic examination. APAP and PTCA produced dose-dependent effects. At 4 hr after the highest dose of APAP, hepatic GSH and Cys concentrations were reduced to 5 and 14%, respectively, of values in vehicle-treated controls, and the GSSG concentration was below the sensitivity of the analytical method. At 24 hr, recovery of hepatic sulfhydryls was incomplete, and there was hepatic necrosis with an approximately 100-fold increase in SGPT activity. At the highest dose of PTCA, the concentrations of GSH, Cys, and GSSG at 4 hr after APAP (800 mg/kg) were 66, 116, and 111%, respectively, of vehicle controls. PTCA in doses of 1.75 to 5 mmol/kg attenuated the APAP-induced increases in SGPT activity. It was concluded that the protective effect of PTCA is most likely related to prevention of hepatic sulfhydryl depletion.
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Affiliation(s)
- C Srinivasan
- Department of Pharmacology and Toxicology, School of Medicine, University of Louisville, Louisville, KY 40292, USA
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Abstract
The copper metallochaperone Cox17 is proposed to shuttle Cu(I) ions to the mitochondrion for the assembly of cytochrome c oxidase. The Cu(I) ions are liganded by cysteinyl thiolates. Mutational analysis on the yeast Cox17 reveals three of the seven cysteinyl residues to be critical for Cox17 function, and these three residues are present in a Cys-Cys-Xaa-Cys sequence motif. Single substitution of any of these three cysteines with serines results in a nonfunctional cytochrome oxidase complex. Cells harboring such a mutation fail to grow on nonfermentable carbon sources and have no cytochrome c oxidase activity in isolated mitochondria. Wild-type Cox17 purified as untagged protein binds three Cu(I) ions/molecule. Mutant proteins lacking only one of these critical Cys residues retain the ability to bind three Cu(I) ions and are imported within the mitochondria. In contrast, Cox17 molecules with a double Cys --> Ser mutation exhibit no Cu(I) binding but are still localized to the mitochondria. Thus, mitochondrial uptake of Cox17 is not restricted to the Cu(I) conformer of Cox17. COX17 was originally cloned by virtue of complementation of a mutant containing a nonfunctional Cys --> Tyr substitution at codon 57. The mutant C57Y Cox17 fails to accumulate within the mitochondria but retains the ability to bind three Cu(I) ions. A C57S Cox17 variant is functional, and a quadruple Cox17 mutant with C16S/C36S/C47S/C57S substitutions binds three Cu(I) ions. Thus, only three cysteinyl residues are important for the ligation of three Cu(I) ions. A novel mode of Cu(I) binding is predicted.
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Affiliation(s)
- D Heaton
- University of Utah Health Sciences Center, Departments of Medicine and Biochemistry, Salt Lake City, Utah 84132, USA
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Srinivasan C, Liba A, Imlay JA, Valentine JS, Gralla EB. Yeast lacking superoxide dismutase(s) show elevated levels of "free iron" as measured by whole cell electron paramagnetic resonance. J Biol Chem 2000; 275:29187-92. [PMID: 10882731 DOI: 10.1074/jbc.m004239200] [Citation(s) in RCA: 110] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
A current hypothesis explaining the toxicity of superoxide anion in vivo is that it oxidizes exposed [4Fe-4S] clusters in certain vulnerable enzymes causing release of iron and enzyme inactivation. The resulting increased levels of "free iron" catalyze deleterious oxidative reactions in the cell. In this study, we used low temperature Fe(III) electron paramagnetic resonance (EPR) spectroscopy to monitor iron status in whole cells of the unicellular eukaryote, Saccharomyces cerevisiae. The experimental protocol involved treatment of the cells with desferrioxamine, a cell-permeant, Fe(III)-specific chelator, to promote oxidation of all of the "free iron" to the Fe(III) state wherein it is EPR-detectable. Using this method, a small amount of EPR-detectable iron was detected in the wild-type strain, whereas significantly elevated levels were found in strains lacking CuZn-superoxide dismutase (CuZn-SOD) (sod1 delta), Mn-SOD (sod2 delta), or both SODs, throughout their growth but particularly in stationary phase. The accumulation was suppressed by expression of wild-type human CuZn-SOD (in the sod1 delta mutant), by pmr1, a genetic suppressor of the sod delta mutant phenotype (in the sod1 delta sod2 delta double knockout strain), and by anaerobic growth. In wild-type cells, an increase in the EPR-detectable iron pool could be induced by treatment with paraquat, a redox-cycling drug that generates superoxide. Cells that were not pretreated with desferrioxamine had Fe(III) EPR signals that were equally as strong as those from treated cells, indicating that "free iron" accumulated in the ferric form in our strains in vivo. Our results indicate a relationship between superoxide stress and iron handling and support the above hypothesis for superoxide-related oxidative damage.
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Affiliation(s)
- C Srinivasan
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095-1569, USA
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Bird AJ, Zhao H, Luo H, Jensen LT, Srinivasan C, Evans-Galea M, Winge DR, Eide DJ. A dual role for zinc fingers in both DNA binding and zinc sensing by the Zap1 transcriptional activator. EMBO J 2000; 19:3704-13. [PMID: 10899124 PMCID: PMC313982 DOI: 10.1093/emboj/19.14.3704] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The Zap1 transcriptional activator of Saccharomyces cerevisiae controls zinc homeostasis. Zap1 induces target gene expression in zinc-limited cells and is repressed by high zinc. One such target gene is ZAP1 itself. In this report, we examine how zinc regulates Zap1 function. First, we show that transcriptional autoregulation of Zap1 is a minor component of zinc responsiveness; most regulation of Zap1 activity occurs post-translationally. Secondly, nuclear localization of Zap1 does not change in response to zinc, suggesting that zinc regulates DNA binding and/or activation domain function. To understand how Zap1 responds to zinc, we performed a functional dissection of the protein. Zap1 contains two activation domains. DNA-binding activity is conferred by five C-terminal C(2)H(2) zinc fingers and each finger is required for high-affinity DNA binding. The zinc-responsive domain of Zap1 also maps to the C-terminal zinc fingers. Furthermore, mutations that disrupt some of these fingers cause constitutive activity of a bifunctional Gal4 DNA-binding domain-Zap1 fusion protein. These results demonstrate a novel function of Zap1 zinc fingers in zinc sensing as well as DNA binding.
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Affiliation(s)
- A J Bird
- Department of Nutritional Sciences, University of Missouri-Columbia, Columbia, MO 65211, USA
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Viele K, Srinivasan C. Parsimonious estimation of multiplicative interaction in analysis of variance using Kullback–Leibler Information. J Stat Plan Inference 2000. [DOI: 10.1016/s0378-3758(99)00151-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Srinivasan C, Minadeo N, Geraldes CF, Mota de Freitas D. Competition between Li+ and Mg2+ for red blood cell membrane phospholipids: A 31P, 7Li, and 6Li nuclear magnetic resonance study. Lipids 1999; 34:1211-21. [PMID: 10606045 DOI: 10.1007/s11745-999-0474-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The mode of action of the lithium ion (Li+) in the treatment of manic depression or bipolar illness is still under investigation, although this inorganic drug has been in clinical use for 50 yr. Several research reports have provided evidence for Li+/Mg2+ competition in biomolecules. We carried out this study to characterize the interactions of Li+ and Mg2+ with red blood cell (RBC) membrane components to see whether Li+/Mg2+ competition occurs. 31P nuclear magnetic resonance chemical shift measurements of the phospholipids extracted from the RBC membranes indicated that the anionic phospholipids, phosphatidylserine and phosphatidylinositol, bind Li+ and Mg2+ most strongly. From 6Li relaxation measurements, the Li+ binding constant to the phospholipid extract was found to be 45 +/- 5 M(-1). Thus, these studies showed that the phospholipids play a major role in metal ion binding. 7Li spin-lattice relaxation measurements conducted on unsealed and cytoskeleton-depleted RBC membrane in the presence of magnesium indicated that the removal of the cytoskeleton increases lithium binding to the more exposed anionic phospholipids (357 +/- 24 M(-1)) when compared to lithium binding in the unsealed RBC membrane (221 +/- 21 M(-1)). Therefore, it can be seen that the cytoskeleton does not play a major role in Li+ binding or in Li+/Mg2+ competition.
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Affiliation(s)
- C Srinivasan
- Department of Chemistry, Loyola University Chicago, Illinois 60626, USA
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Abstract
Mac1 is a metalloregulatory protein that regulates expression of the high affinity copper transport system in the yeast Saccharomyces cerevisiae. Under conditions of high copper concentration, Mac1 represses transcription of genes coding for copper transport proteins. Mac1 binds to DNA sequences called copper response elements (CuREs), which have the consensus sequence 5'-TTTGC(T/G)C(A/G)-3'. Mac1 contains two zinc binding sites, a copper binding site, and the sequence motif RGRP, which has been found in other proteins to mediate binding to the minor groove of A/T-rich sequences in DNA. We have used hydroxyl radical footprinting, missing nucleoside, and methylation interference experiments to investigate the structure of the complex of the DNA binding domain of Mac1 (called here Mac1(t)) with the two CuRE sites found in the yeast CTR1 promoter. We conclude from these experiments that Mac1(t) binds in a modular fashion to DNA, with its RGRP AT-hook motif interacting with the TTT sequence at the 5' end of the CTR1 CuRE site, and with another DNA-binding module(s) binding in the adjacent major groove in the GCTCA sequence.
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Affiliation(s)
- C P Jamison McDaniels
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, USA
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Srinivasan C, Minadeo N, Toon J, Graham D, Mota de Freitas D, Geraldes CF. Competition between Na(+) and Li(+) for unsealed and cytoskeleton-depleted human red blood cell membrane: a (23)Na multiple quantum filtered and (7)Li NMR relaxation study. J Magn Reson 1999; 140:206-217. [PMID: 10479564 DOI: 10.1006/jmre.1999.1813] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Evidence for competition between Li(+) and Na(+) for binding sites of human unsealed and cytoskeleton-depleted human red blood cell (csdRBC) membranes was obtained from the effect of added Li(+) upon the (23)Na double quantum filtered (DQF) and triple quantum filtered (TQF) NMR signals of Na(+)-containing red blood cell (RBC) membrane suspensions. We found that, at low ionic strength, the observed quenching effect of Li(+) on the (23)Na TQF and DQF signal intensity probed Li(+)/Na(+) competition for isotropic binding sites only. Membrane cytoskeleton depletion significantly decreased the isotropic signal intensity, strongly affecting the binding of Na(+) to isotropic membrane sites, but had no effect on Li(+)/Na(+) competition for those sites. Through the observed (23)Na DQF NMR spectra, which allow probing of both isotropic and anisotropic Na(+) motion, we found anisotropic membrane binding sites for Na(+) when the total ionic strength was higher than 40 mM. This is a consequence of ionic strength effects on the conformation of the cytoskeleton, in particular on the dimer-tetramer equilibrium of spectrin. The determinant involvement of the cytoskeleton in the anisotropy of Na(+) motion at the membrane surface was demonstrated by the isotropy of the DQF spectra of csdRBC membranes even at high ionic strength. Li(+) addition initially quenched the isotropic signal the most, indicating preferential Li(+)/Na(+) competition for the isotropic membrane sites. High ionic strength also increased the intensity of the anisotropic signal, due to its effect on the restructuring of the membrane cytoskeleton. Further Li(+) addition competed with Na(+) for those sites, quenching the anisotropic signal. (7)Li T(1) relaxation data for Li(+)-containing suspensions of unsealed and csdRBC membranes, in the absence and presence of Na(+) at low ionic strength, showed that cytoskeleton depletion does not affect the affinity of Na(+) for the RBC membrane, but increases the affinity of Li(+) by 50%. This clearly indicates that cytoskeleton depletion favors Li(+) relative to Na(+) binding, and thus Li(+)/Na(+) competition for its isotropic sites. Thus, this relaxation technique proves to be very sensitive to alkali metal binding to the membrane, detecting a more pronounced steric hindrance effect of the cytoskeleton network to binding of the larger hydrated Li(+) ion to the membrane phosphate groups.
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Affiliation(s)
- C Srinivasan
- Department of Chemistry, Loyola University of Chicago, 6525 N. Sheridan Road, Chicago, Illinois 60626, USA
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Shayira Banu H, Lalitha A, Srinivasan C, Pitchumani K. Modification of photochemical reactivity of trans-2-styrylpyridine: effect of cyclodextrin complexation. Chem Commun (Camb) 1999. [DOI: 10.1039/a809372e] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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32
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Jensen LT, Posewitz MC, Srinivasan C, Winge DR. Mapping of the DNA binding domain of the copper-responsive transcription factor Mac1 from Saccharomyces cerevisiae. J Biol Chem 1998; 273:23805-11. [PMID: 9726991 DOI: 10.1074/jbc.273.37.23805] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mac1 from Saccharomyces cerevisiae activates transcription of genes, including CTR1 in copper-deficient cells. N-terminal fusions of Mac1 with the herpes simplex VP16 activation domain were used to show that residues 1-159 in Mac1 constitute the minimal DNA binding domain. Mac1-(1-159) purified from Escherichia coli contains two bound Zn(II) ions. Electrophoretic mobility shift assays showed direct and specific binding by Mac1-(1-159) to a DNA duplex containing the copper-responsive element TTTGCTCA. The DNA binding affinity of Mac1-(1-159) for a duplex containing a single promoter element or an inverted repeat was 5 nM for the 1:1 complex. The N-terminal 40-residue segment of Mac1 is homologous to the DNA binding zinc module found in the copper-activated transcription factors Ace1 and Amt1. A MAC1 mutation yielding a Cys11 --> Tyr substitution at the first candidate zinc ligand position relative to Ace1 resulted in a loss of in vivo function. Two TTTGCTCA promoter elements are necessary for efficient Mac1-mediated transcriptional activation. The elements appear to function synergistically. Increasing the number of elements yields more than additive enhancements in CTR1 expression.
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Affiliation(s)
- L T Jensen
- Departments of Medicine and Biochemistry, University of Utah Health Science Center, Salt Lake City, Utah 84132, USA
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33
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Abstract
Assembly of functional cytochrome oxidase in yeast requires Cox17, which has been postulated to deliver copper ions to the mitochondrion for insertion into the enzyme. This role for Cox17 is supported by the observation that it binds copper as a binuclear cuprous-thiolate cluster. X-ray absorption spectroscopy, together with UV-visible absorption and emission spectroscopy, indicates the presence of bound cuprous ions, trigonally coordinated by thiolate ligands. Analysis of the EXAFS shows three Cu-S bonds at 2.26 A, plus a short Cu-Cu distance of 2.7 A, indicating a binuclear cluster in Cox17. The cuprous-thiolate cluster in Cox17 is substantially more labile than structurally related clusters in metallothioneins.
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Affiliation(s)
- C Srinivasan
- University of Utah Health Sciences Center, Salt Lake City 84132, USA
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Abstract
Metal-responsive transcription factors exist in yeast to modulate expression of genes that encode proteins involved in cellular uptake of copper, iron and zinc ions. These signal transduction pathways function in the cellular regulation of the intracellular concentration of free metal ions. A second component of metal homeostasis is the regulation of metal-ion binding through protein-mediated metallation. Copper-specific chaperones exist in yeast that route copper ions to the site of biosynthesis of copper-metalloenzymes.
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Affiliation(s)
- D R Winge
- University of Utah Health Sciences Center, Salt Lake City, UT 84132, USA.
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Thanasekaran P, Rajendran T, Rajagopal S, Srinivasan C, Ramaraj R, Ramamurthy P, Venkatachalapathy B. Marcus Inverted Region in the Photoinduced Electron Transfer Reactions of Ruthenium(II)−Polypyridine Complexes with Phenolate Ions. J Phys Chem A 1997. [DOI: 10.1021/jp971746v] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- P. Thanasekaran
- School of Chemistry and Department of Materials Science, Madurai Kamaraj University, Madurai 625 021, India, and Department of Inorganic Chemistry, University of Madras, Madras 600 025, India
| | - T. Rajendran
- School of Chemistry and Department of Materials Science, Madurai Kamaraj University, Madurai 625 021, India, and Department of Inorganic Chemistry, University of Madras, Madras 600 025, India
| | - S. Rajagopal
- School of Chemistry and Department of Materials Science, Madurai Kamaraj University, Madurai 625 021, India, and Department of Inorganic Chemistry, University of Madras, Madras 600 025, India
| | - C. Srinivasan
- School of Chemistry and Department of Materials Science, Madurai Kamaraj University, Madurai 625 021, India, and Department of Inorganic Chemistry, University of Madras, Madras 600 025, India
| | - R. Ramaraj
- School of Chemistry and Department of Materials Science, Madurai Kamaraj University, Madurai 625 021, India, and Department of Inorganic Chemistry, University of Madras, Madras 600 025, India
| | - P. Ramamurthy
- School of Chemistry and Department of Materials Science, Madurai Kamaraj University, Madurai 625 021, India, and Department of Inorganic Chemistry, University of Madras, Madras 600 025, India
| | - B. Venkatachalapathy
- School of Chemistry and Department of Materials Science, Madurai Kamaraj University, Madurai 625 021, India, and Department of Inorganic Chemistry, University of Madras, Madras 600 025, India
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Kannan P, Pitchumani K, Rajagopal S, Srinivasan C. Sheet silicate catalysed demethylation and Fischer-Hepp rearrangement of N-methyl-N-nitrosoaniline. ACTA ACUST UNITED AC 1997. [DOI: 10.1016/s1381-1169(96)00401-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Kannan P, Pitchumani K, Rajagopal S, Srinivasan C. Synthesis of organic sulfides from thiols using montmorillonite-3-aminopropyltriethoxysilane as a new catalyst. Chem Commun (Camb) 1996. [DOI: 10.1039/cc9960000369] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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40
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Rajagopal S, Srinivasan C, Gnanaraj GA. Nonadiabaticity in the photoinduced electron transfer reactions of metal complexes. J CHEM SCI 1994. [DOI: 10.1007/bf02911095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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41
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Mota de Freitas D, Amari L, Srinivasan C, Rong Q, Ramasamy R, Abraha A, Geraldes CF, Boyd MK. Competition between Li+ and Mg2+ for the phosphate groups in the human erythrocyte membrane and ATP: an NMR and fluorescence study. Biochemistry 1994; 33:4101-10. [PMID: 8155627 DOI: 10.1021/bi00180a002] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
We investigated the mechanism of competition between Li+ and Mg2+ in Li(+)-loaded human red blood cells (RBCs) by making 7Li and 31P NMR and fluorescence measurements. We used 7Li NMR relaxation times to probe Li+ binding to the human RBC membrane and ATP; an increase in Mg2+ concentration caused an increase in both 7Li T1 and T2 values in packed Li(+)-loaded RBCs, in suspensions of Li(+)-loaded RBC ghosts, in suspensions of Li(+)-containing RBC membrane, and in aqueous solutions of ATP, indicating competition between Li+ and Mg2+ for binding sites in the membrane and ATP. We found that increasing concentrations of either Li+ or Mg2+ in the presence of human RBC membrane caused an increase in the 31P NMR chemical shift anisotropy parameter, which describes the observed axially symmetric powder pattern, indicating metal ion binding to the phosphate groups in the membrane. Competition between Li+ and Mg2+ for phosphate groups in ATP and in the RBC membrane was also observed by both fluorescence measurements and 31P NMR spectroscopy at low temperature. The ratio of the stoichiometric binding constants of Mg2+ to Li+ to the RBC membrane was approximately 20; the ratio of the conditional binding constants in the presence of a free intracellular ATP concentration of 0.2 mM was approximately 4, indicating that Li+ competes for approximately 20% of the Mg(2+)-binding sites in the RBC membrane. Our results indicate that, regardless of the spectroscopic method used, Li+ competes with Mg2+ for phosphate groups in both ATP and the RBC membrane; the extent of metal ion competition for the phosphate head groups of the phospholipids in the RBC membrane is enhanced by the presence of ATP. Competition between Li+ and Mg2+ for anionic phospholipids or Mg(2+)-activated proteins present in cell membranes may constitute the basis of a general molecular mechanism for Li+ action in human tissues.
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Affiliation(s)
- D Mota de Freitas
- Department of Chemistry, Loyola University of Chicago, Illinois 60626
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42
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Zhong H, Bolyard MG, Srinivasan C, Sticklen MB. Transgenic plants of turfgrass (Agrostis palustris Huds.) from microprojectile bombardment of embryogenic callus. Plant Cell Rep 1993; 13:1-6. [PMID: 24196173 DOI: 10.1007/bf00232305] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/1993] [Revised: 07/27/1993] [Indexed: 06/02/2023]
Abstract
Transgenic creeping bentgrass (Agrostis palustris Huds., cv. Pencross; Poaceae) plants have been obtained by microprojectile bombardment of and regeneration from embryogenic calli with a vector designed to deliver the β-glucuronidase (GUS) gene under the control of rice actin 1 5' regulatory sequences. Southern analysis of polymerase chain reaction (PCR)-amplified and restriction-digested genomic DNA of four transgenic plants regenerated from these cultures showed the unscrambled integration of the gus fragment. Northern blot analysis confirmed the expression of gus mRNA in one of the transgenic plants. Western blot analysis revealed a high level of accumulation of gus protein. Histochemical assays showed enzymatic activity of β-glucuronidase in all parts of the transgenic turfgrass plant. The order of gus expression level in different tissues of the transgenic plant is as follows: stem node > first young leaf > root tip > second / third / fourth young leaf > stem internode > root hair-zone.
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Affiliation(s)
- H Zhong
- Departments of Crop and Soil Sciences and of Entomology, 202 Pesticide Research Center, Michigan State University, 48824-1311, East Lansing, MI, USA
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Zhong H, Srinivasan C, Sticklen MB. In-vitro morphogenesis of corn (Zea mays L.) : I. Differentiation of multiple shoot clumps and somatic embryos from shoot tips. Planta 1992; 187:483-489. [PMID: 24178142 DOI: 10.1007/bf00199966] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/1991] [Accepted: 03/23/1992] [Indexed: 06/02/2023]
Abstract
In-vitro methods have been developed to regenerate clumps of multiple shoots and somatic embryos at high frequency from shoot tips of aseptically-grown seedlings as well as from shoot apices of precociously-germinated immature zygotic embryos of corn (Zea mays L.). About 500 shoots were produced from a shoot tip after eight weeks of culture (primary culture and one subculture of four weeks) in darkness on Murashige and Skoog basal medium (MS) supplemented with 500 mg/L casein hydrolysate (CH) and 9 μM N(6)-benzyladenine (BA). In this medium, shoots formed in shoot tips as tightly packed "multiple shoot clumps" (MSC), which were composed of some axillary shoots and many adventitious shoots. When the shoot tips were cultured on MS medium containing 500 mg/L CH, 9 μM BA and 2.25 μM 2,4-dichlorophenoxyacetic acid (2,4-D), most of the shoots in the clumps were adventitious in origin. Similar shoot tips cultured on MS medium containing 500 mg/L CH, 4.5 μM BA and 2.25 μM 2,4-D regenerated many somatic embryos within eight weeks of culture. Somatic embryos were produced either directly from the shoot apical meristems or from calli derived from the shoots apices. Both the MSC and the embryos produced normal shoots on MS medium containing 2.25 μM BA and 1.8 μM indole-3-butyric acid (IBA). These shoots were rooted on MS medium containing 3.6 μM IBA, and fertile corn plants were grown in the greenhouse. The sweet-corn genotype, Honey N Pearl, was used for the experiments described above, but shoot-tip cultures from all of 19 other corn genotypes tested also formed MSC on MS medium containing 500 mg/L CH and 9 μM BA.
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Affiliation(s)
- H Zhong
- Departments of Crop and Soil Sciences and of Entomology, 202 Pesticide Research Center, Michigan State University, 48824-1311, East Lansing, MI, USA
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Zhong H, Srinivasan C, Sticklen MB. In-vitro morphogenesis of corn (Zea mays L.) : II. Differentiation of ear and tassel clusters from cultured shoot apices and immature inflorescences. Planta 1992; 187:490-497. [PMID: 24178143 DOI: 10.1007/bf00199967] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/1992] [Accepted: 03/23/1992] [Indexed: 06/02/2023]
Abstract
The objective of this research was to study the in-vitro morphogenetic pattern of corn (Zea mays L.) shoot tips excised from aseptically-grown seedlings, and of expiants of axillary shoot buds, immature tassels and ears (staminate and pistillate inflorescences) obtained from greenhouse-grown corn plants. The seedling shoot tips and immature ears first regenerated clumps of multiple shoots within four weeks of culture on Murashige and Skoog (MS) basal medium supplemented with 500 mg/L casein hydrolysate (CH) and 9.0 μM N(6)-benzyladenine (BA). Multiple shoot clumps were also differentiated from spikelets of immature tassels cultured on MS medium containing 500 mg/L CH, 4.5 μM BA and 0.45 μM 2,4-dichlorophenoxy acetic acid (2,4-D). All these multiple shoot clumps in turn differentiated clusters of ears after further four subcultures at four-week intervals under light on MS medium supplemented with 500 mg/L CH and 2.25, 4.5, 9.0 or 18 μM BA. Axillary shoot buds readily differentiated clusters of ears within four weeks of the initial culture on these media. Secondary and tertiary ear clusters were initiated following subculture of primary ears on MS medium containing 500 mg/L CH and 4.5 or 9.0 μM BA. Most of the ear primordia developed into ears with well-developed ovaries and styles on subculture on MS medium containing 500 mg/L CH and 1.0 μM BA. Corn kernels were obtained after pollination of in-vitro-formed ears with pollens collected from greenhouse-grown corn. These kernels germinated in vitro and developed into mature corn plants in the greenhouse. Clusters of tassels were also differentiated in darkness from the multiple shoot clumps after six months successive subcultures but the spikelet primordia of tassels failed to develop fully under the in-vitro conditions tested. Somatic embryos arose directly from spikelet primordia of young tassels or ears on MS medium containing 500 mg/L CH and 4.5 μM 2,4-D, or indirectly from calli derived from spikelets of young tassels and ears on MS medium containing 500 mg/L CH and 9.0 μM 2.4-D.
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Affiliation(s)
- H Zhong
- Departments of Crop and Soil Sciences and of Entomology, 202 Pesticide Research Center, Michigan State University, 48824-1311, East Lansing, MI, USA
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Pitchumani K, Subramanian V, Jegatheesan PP, Srinivasan C. Kinetics and mechanism of oxidation of N-substituted phenothiazines by chromium(VI). J CHEM SCI 1992. [DOI: 10.1007/bf02843527] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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46
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Gnanaraj GA, Rajagopal S, Srinivasan C. Excited state electron transfer reactions of tris(2,2′-bipyridine) chromium (III) ion with organic sulphides. J CHEM SCI 1992. [DOI: 10.1007/bf02843520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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47
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Zhong H, Srinivasan C, Sticklen MB. Plant regeneration via somatic embryogenesis in creeping bentgrass (Agrostis palustris Huds.). Plant Cell Rep 1991; 10:453-456. [PMID: 24221850 DOI: 10.1007/bf00233813] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/1991] [Revised: 07/18/1991] [Indexed: 06/02/2023]
Abstract
We have established a high-frequency plant regeneration system via somatic embryogenesis from mature seeds of creeping bentgrass (Agrostis palustris Huds). The effects of 2,4-dichlorophenoxyacetic acid (2,4-D), 3.6-dichloroo-anisic acid (dicamba) and 6-benzyladenine (BA) on callus formation and embryogenesis were evaluated. Callus produced on the Murashige and Skoog (MS) (1962) medium containing 2,4-D had low embryogenic potency. In the presence of 30 μM dicamba, addition of 2.25 to 9 μM BA significantly enhanced embryogenic callus formation over dicamba alone. Optimum frequency of somatic embryogenesis was achieved on MS basal medium containing 30 μM dicamba and 2.25 μM BA. Over 80% of somatic embryos germinated and formed plantlets on half-strength MS basal medium. These plantlets grew normally in the greenhouse.
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Affiliation(s)
- H Zhong
- Departments of Crop and Soil Sciences and Entomology, 202 Pesticide Research Center, Michigan State University, 48824-1311, East Lansing, MI, USA
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Rajagopal S, Sivasubramanian G, Suthakaran R, Srinivasan C. Mechanism of permanganate ion oxidation of diaryl sulphoxides — A kinetic study. J CHEM SCI 1991. [DOI: 10.1007/bf02841065] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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49
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Pitchumani K, Durai Manickam M, Srinivasan C. Effect of cyclodextrin encapsulation on photo-fries rearrangement of benzensulphonanilide. Tetrahedron Lett 1991. [DOI: 10.1016/0040-4039(91)80666-t] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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50
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Dey DK, Ghosh M, Srinivasan C. A NEW CLASS OF IMPROVED ESTIMATORS OF A MULTINORMAL PRECISION MATRIX. Statistics & Risk Modeling 1990. [DOI: 10.1524/strm.1990.8.2.141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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