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Haupts U, Maiti S, Schwille P, Webb WW. Dynamics of fluorescence fluctuations in green fluorescent protein observed by fluorescence correlation spectroscopy. Proc Natl Acad Sci U S A 1998; 95:13573-8. [PMID: 9811841 PMCID: PMC24860 DOI: 10.1073/pnas.95.23.13573] [Citation(s) in RCA: 416] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We have investigated the pH dependence of the dynamics of conformational fluctuations of green fluorescent protein mutants EGFP (F64L/S65T) and GFP-S65T in small ensembles of molecules in solution by using fluorescence correlation spectroscopy (FCS). FCS utilizes time-resolved measurements of fluctuations in the molecular fluorescence emission for determination of the intrinsic dynamics and thermodynamics of all processes that affect the fluorescence. Fluorescence excitation of a bulk solution of EGFP decreases to zero at low pH (pKa = 5.8) paralleled by a decrease of the absorption at 488 nm and an increase at 400 nm. Protonation of the hydroxyl group of Tyr-66, which is part of the chromophore, induces these changes. When FCS is used the fluctuations in the protonation state of the chromophore are time resolved. The autocorrelation function of fluorescence emission shows contributions from two chemical relaxation processes as well as diffusional concentration fluctuations. The time constant of the fast, pH-dependent chemical process decreases with pH from 300 microseconds at pH 7 to 45 microseconds at pH 5, while the time-average fraction of molecules in a nonfluorescent state increases to 80% in the same range. A second, pH-independent, process with a time constant of 340 microseconds and an associated fraction of 13% nonfluorescent molecules is observed between pH 8 and 11, possibly representing an internal proton transfer process and associated conformational rearrangements. The FCS data provide direct measures of the dynamics and the equilibrium properties of the protonation processes. Thus FCS is a convenient, intrinsically calibrated method for pH measurements in subfemtoliter volumes with nanomolar concentrations of EGFP.
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Jaman AI, Maiti S, Nandi RN. Microwave Spectrum and Barrier to Internal Rotation in ortho-Tolunitrile. JOURNAL OF MOLECULAR SPECTROSCOPY 1998; 192:148-151. [PMID: 9770397 DOI: 10.1006/jmsp.1998.7676] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The microwave rotational spectra of ortho-tolunitrile (C6H4CH3CN) have been investigated in the ground torsional state in the frequency ranges of 22.0-26.0 GHz and 32.0-37.0 GHz. The true rotational constants were determined to be Ar = 2890.98 MHz, Br = 1499.75 MHz, and Cr = 993.58 MHz. A least-squares analysis of the A - E splittings of 16 transitions resulted in the values of V3 = 533.53 cal/mol and thetaa = 54.22 degrees, assuming V6 = 0 and Ialpha = 3.2 a.m.u. Å2. Copyright 1998 Academic Press.
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103
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Bag PK, Maiti S, Sharma C, Ghosh A, Basu A, Mitra R, Bhattacharya SK, Nakamura S, Yamasaki S, Takeda Y, Balakrish Nair G. Rapid spread of the new clone of Vibrio cholerae O1 biotype El Tor in cholera endemic areas in India. Epidemiol Infect 1998; 121:245-51. [PMID: 9825773 PMCID: PMC2809519 DOI: 10.1017/s0950268898001423] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Using molecular techniques, we investigated whether the clone of Vibrio cholerae O1 biotype El Tor which appeared in Calcutta, India, in 1994 has spread to other cholera endemic areas in the country. The ribotype of 31 of the 33 strains isolated from different parts of India during 1996 and 1997 was identical to the ribotype displayed by the new clone of V. cholerae O1 which emerged in Calcutta in 1994. Likewise, 12 of the 15 strains examined by pulsed-field gel electrophoresis (PFGE) showed identical profile to that exhibited by the new clone of O1. The restriction fragment length polymorphism (RFLP) of CTX genetic element of these strains also matched with the new clone of O1 which emerged after the outbreak of V. cholerae 0139 in Calcutta. However, two strains (AH042 and AH046) isolated from an outbreak in Ahmedabad (western India) showed different CTX RFLP but had the same ribotype and PFGE profile as the new clone, whereas one strain from Goa (G2) showed distinct ribotype and PFGE profile and the CTX RFLP was identical to the O1 strains which prevailed before the genesis of 0139 in Calcutta. The drug resistance pattern of most of the O1 strains examined in this study, except strain G2, was similar to that of the new clone of V. cholerae O1. None of the strains in this study carried plasmids. Molecular studies clearly show that the new expanded drug resistant clone of V. cholerae O1 has spread to all cholera endemic areas in India and also provide evidence for the evolution of new clones of the O1 serogroup.
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Sutton KA, Maiti S, Tribley WA, Lindsey JS, Meistrich ML, Bucana CD, Sanborn BM, Joseph DR, Griswold MD, Cornwall GA, Wilkinson MF. Androgen regulation of the Pem homeodomain gene in mice and rat Sertoli and epididymal cells. JOURNAL OF ANDROLOGY 1998; 19:21-30. [PMID: 9537288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Although the role of homeodomain transcription factors during embryogenesis is well known, their developmental function in postnatal animals is only beginning to be understood. We examined the regulation and expression pattern of Pem, a homeodomain protein that may regulate androgen-dependent events in the testis and epididymis. Immunohistochemical analysis showed that Pem protein is expressed selectively in the nuclei of Sertoli cells during the androgen-dependent stage of the seminiferous epithelium cycle in vivo. RNase protection analysis revealed that a proximal promoter was responsible for androgen-dependent mouse Pem expression in testis and epididymis in vivo, whereas a distal promoter was used in placenta. The mouse Pem gene was expressed at approximately 10-fold higher levels in the testis than in the epididymis; conversely, the rat Pem gene was expressed at >10-fold higher levels in the epididymis than in the testis. Because androgen-binding protein has been proposed to transport androgens from the testis to the epididymis, we tested whether the > or = 20-fold higher levels of androgen-binding protein expression in the rat, compared to that of mouse, are responsible for the differential expression of Pem in these two rodent species. Studies with androgen-binding protein transgenic mice demonstrated that the species-specific difference in androgen-binding protein expression is unlikely to be responsible for the species-specific difference in Pem expression. We found that androgen is necessary but not sufficient for Pem expression, since purified Sertoli cells rapidly down-regulated Pem transcripts in culture, regardless of the presence of testosterone. We conclude that Pem gene expression in Sertoli cells requires other cell types or cellular factors in addition to androgen.
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106
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Sharma C, Maiti S, Mukhopadhyay AK, Basu A, Basu I, Nair GB, Mukhopadhyaya R, Das B, Kar S, Ghosh RK, Ghosh A. Unique organization of the CTX genetic element in Vibrio cholerae O139 strains which reemerged in Calcutta, India, in September 1996. J Clin Microbiol 1997; 35:3348-50. [PMID: 9399556 PMCID: PMC230184 DOI: 10.1128/jcm.35.12.3348-3350.1997] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
We studied the restriction fragment length polymorphism of the rRNA gene and CTX genetic element in Vibrio cholerae O139 Bengal, which resurged in Calcutta in September 1996 after a gap of 32 months. While the strains from this resurgence were indistinguishable from the earlier strains by ribotyping, the structure of the CTX genetic element present in the current O139 strains was found to be unconventional.
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107
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Maiti S, Haupts U, Webb WW. Fluorescence correlation spectroscopy: diagnostics for sparse molecules. Proc Natl Acad Sci U S A 1997; 94:11753-7. [PMID: 9342306 PMCID: PMC33774 DOI: 10.1073/pnas.94.22.11753] [Citation(s) in RCA: 227] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The robust glow of molecular fluorescence renders even sparse molecules detectable and susceptible to analysis for concentration, mobility, chemistry, and photophysics. Correlation spectroscopy, a statistical-physics-based tool, gleans quantitative information from the spontaneously fluctuating fluorescence signals obtained from small molecular ensembles. This analytical power is available for studying molecules present at minuscule concentrations in liquid solutions (less than one nanomolar), or even on the surfaces of living cells at less than one macromolecule per square micrometer. Indeed, routines are becoming common to detect, locate, and examine individual molecules under favorable conditions.
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108
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Ghosh AK, Maiti S, Adhikari B, Ray GS, Mustafi SK. Effect of modified carbon black on the properties of natural rubber vulcanizate. J Appl Polym Sci 1997. [DOI: 10.1002/(sici)1097-4628(19971024)66:4<683::aid-app8>3.0.co;2-o] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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109
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Mazumdar UK, Gupta M, Maiti S, Mukherjee D. Antitumor activity of Hygrophila spinosa on Ehrlich ascites carcinoma and sarcoma-180 induced mice. INDIAN JOURNAL OF EXPERIMENTAL BIOLOGY 1997; 35:473-7. [PMID: 9378516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Petroleum ether extract from H. spinosa root exhibited antitumor activity in Ehrlich ascites carcinoma and Sarcoma-180 bearing mice Processed extract suppressed significantly the tumor fluid volume at the end of 3 weeks experiment. It decreased about 50% of packed cell volume and increased life span of EAC/S-180 bearing mice in a day dependent manner. Red blood cell count, hemoglobin content and white blood cell count were more or less normal after processed extract treatment of the tumor bearing mice. In tumor control animals, neutrophils increased (273.7% in EAC and 263.4% in S-180 bearing mice respectively with respect to normal mice) whereas lymphocytes decreased (60.0% in EAC and 56.5% in S-180 bearing mice respectively with respect to normal mice). It also inhibited the rapid increase of body weight of tumor bearing mice.
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110
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Maiti S, Bhattacharyya PK. Perineal breast. JOURNAL OF THE INDIAN MEDICAL ASSOCIATION 1997; 95:123. [PMID: 9357284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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111
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Maiti S, Shear JB, Williams RM, Zipfel WR, Webb WW. Measuring serotonin distribution in live cells with three-photon excitation. Science 1997; 275:530-2. [PMID: 8999797 DOI: 10.1126/science.275.5299.530] [Citation(s) in RCA: 347] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Tryptophan and serotonin were imaged with infrared illumination by three-photon excitation (3PE) of their native ultraviolet (UV) fluorescence. This technique, established by 3PE cross section measurements of tryptophan and the monoamines serotonin and dopamine, circumvents the limitations imposed by photodamage, scattering, and indiscriminate background encountered in other UV microscopies. Three-dimensionally resolved images are presented along with measurements of the serotonin concentration ( approximately 50 mM) and content (up to approximately 5 x 10(8) molecules) of individual secretory granules.
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112
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Mazumdar UK, Gupta M, Maiti S. Effect of petroleum ether extract from Hygrophila spinosa on hematological parameters and hepatorenal functions in mice. INDIAN JOURNAL OF EXPERIMENTAL BIOLOGY 1996; 34:1201-3. [PMID: 9246910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Multiple doses of H. spinosa were administered, ip once in a week for 4 weeks (20, 40 and 80 mg/kg body weight) and daily for one month (2, 4 and 8 mg/kg body weight). No alteration in biochemical parameters at low and moderate dose level of daily and low dose level of weekly treatment of petroleum ether extract was observed. However, the extract at moderate dose level in weekly treatment changed serum aminotransferase, alkaline phosphatase and plasma cholesterol significantly. High dose level of the extract changed all the above parameters of weekly treated mice including total bilirubin, nonprotein nitrogen, blood urea and plasma protein. High dose level of daily treatment and moderate and high dose level of weekly treatment of the root extract increased only the white blood cell count significantly. The results reveal that the weekly moderate and high dose (above 40 mg/kg body weight) and daily/therapeutic high dose (8 mg/kg) of the petroleum ether extract of H. spinosa affects liver and kidney functions and metabolism and hematological parameters whereas low weekly dose (20 mg/kg) and low and moderate daily/therapeutic dose (2 and 4 mg/kg) does not exhibit any appreciable toxic action.
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113
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Maiti S, Doskow J, Li S, Nhim RP, Lindsey JS, Wilkinson MF. The Pem homeobox gene. Androgen-dependent and -independent promoters and tissue-specific alternative RNA splicing. J Biol Chem 1996; 271:17536-46. [PMID: 8663309 DOI: 10.1074/jbc.271.29.17536] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The Pem gene encodes an atypical homeodomain protein, distantly related to Prd/Pax family members, that we demonstrate is regulated in a complex transcriptional and post-transcriptional manner. We show that the rat Pem genomic structure includes three 5'-untranslated (5'-UT) exons and four coding exons, three of which encode the homeodomain. Several alternatively spliced transcripts were identified, including one that skips an internal coding exon, enabling this mRNA to express a novel form of the Pem protein. Other alternatively spliced mRNAs were characterized that possess different 5'-UT regions, including a muscle-specific transcript. The different 5'-UT termini present in Pem transcripts conferred different levels of translatability in vitro. Two promoters containing multiple transcription initiation sites were identified: a distal promoter (Pd) in the first 5'-UT exon and a proximal promoter (Pp) located in the "intron" upstream of the first coding exon. The Pd was active in placenta, ovary, tumor cell lines, and to a lesser extent in skeletal muscle. In contrast, transcripts from the Pp were only detectable in testis and epididymis and were only expressed in epididymis in the presence of testosterone. To our knowledge no transcription factors have previously been identified that exhibit androgen-dependent expression in the epididymis.
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114
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Maiti S, Doskow J, Sutton K, Nhim RP, Lawlor DA, Levan K, Lindsey JS, Wilkinson MF. The Pem homeobox gene: rapid evolution of the homeodomain, X chromosomal localization, and expression in reproductive tissue. Genomics 1996; 34:304-16. [PMID: 8786129 DOI: 10.1006/geno.1996.0291] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
A hallmark of homeobox genes is their high degree of sequence conservation in distantly related species. Here, we report the chromosomal localization, sequence, and expression pattern of an orphan homeobox gene, Pem, that encodes a homeodomain (HD) that has undergone a surprisingly high rate of evolutionary change. The N-terminal portion of the Pem HD, which includes the first two alpha-helices, exhibits only 44% sequence identity between rat Pem (r.Pem) and mouse Pem (m.Pem). This N-terminal subdomain exhibited an extremely high frequency of nonsynonymous substitutions, severalfold higher than other regions of the Pem protein. In contrast, the third helix, which is known to confer most of the base-specific contacts of HDs with DNA, was almost identical in r. Pem and m.Pem. Several lines of evidence suggested that the rat and mouse genes that we identified as Pem genes are true homologues: (1) the r.Pem and m.Pem genes both reside on the X chromosome; (2) they possess identical exon/intron splice junctions; (3) they both encode a distinctive motif upstream of the HD that is unique to Pem; and (4) the only m.Pem-like gene we were able to identify in the rat genome other than r.Pem was a pseudogene, r.Pem-ps, whose sequence and chromosomal localization indicated that it was derived by reverse transcription and reinsertion into the genome. The functional r.Pem gene is selectively expressed in placenta, testis, epididymis, and ovary. This expression pattern is of interest since other genes transcribed in reproductive tissue have also been shown to undergo high rates of sequence divergence. The high rate of amino acid substitutions in the N-terminal region of the Pem HD suggests the possibility of species-specific directional selection.
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115
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Maiti S. Some new approaches for the control of a distillation column and their experimental evaluation on a pilot plant. Comput Chem Eng 1995. [DOI: 10.1016/0098-1354(95)00048-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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116
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Lalwani R, Maiti S, Mukherji S. Involvement of H1 and other chromatin proteins in the formation of DNA-protein cross-links induced by visible light in the presence of methylene blue. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 1995; 27:117-22. [PMID: 7714672 DOI: 10.1016/1011-1344(94)07065-v] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The formation of DNA-protein cross-links (DPCs), induced by irradiation with visible light, was studied in methylene blue-treated (MB-treated) chromatin and H1-depleted chromatin. The effects of the MB concentration and radiation dose were studied using sodium dodecylsulphate-chloroform-isoamyl alcohol assay and sodium dodecylsulphate-polyacrylamide gel electrophoresis. Under identical experimental conditions, DPC formation was less in H1-depleted chromatin (70%) than in chromatin (92%). The non-histone proteins and core proteins of chromatin contributed towards DPC formation. Of the core proteins, H2A was more cross-linked than H4, whereas the bands for H2B and H3 melted into one in chromatin and H1-depleted chromatin. In both cases, the gel pattern showed the appearance of two new protein bands with approximate molecular weights of 27 kDa and 29 kDa as a result of histone-histone cross-linking. Viscometric studies showed that the dissociation of the compact structure of chromatin in 2 M NaCl was more extensive in irradiated, MB-treated, H1-depleted chromatin than in irradiated, MB-treated chromatin, indicating a reduction in the amount of DPC formation in H1-depleted chromatin.
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117
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Maiti S, Walker GC, Cowen BR, Pippenger R, Moser CC, Dutton PL, Hochstrasser RM. Femtosecond coherent transient infrared spectroscopy of reaction centers from Rhodobacter sphaeroides. Proc Natl Acad Sci U S A 1994; 91:10360-4. [PMID: 7937956 PMCID: PMC45019 DOI: 10.1073/pnas.91.22.10360] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Protein and cofactor vibrational dynamics associated with photoexcitation and charge separation in the photosynthetic reaction center were investigated with femto-second (300-400 fs) time-resolved infrared (1560-1960 cm-1) spectroscopy. The experiments are in the coherent transient limit where the quantum uncertainty principle governs the evolution of the protein vibrational changes. No significant protein relaxation accompanies charge separation, although the electric field resulting from charge separation modifies the polypeptide carbonyl spectra. The potential energy surfaces of the "special pair" P and the photoexcited singlet state P* and environmental perturbations on them are similar as judged from coherence transfer measurements. The vibrational dephasing time of P* modes in this region is 600 fs. A subpicosecond transient at 1665 cm-1 was found to have the kinetics expected for a sequential electron transfer process. Kinetic signatures of all other transient intermediates, P, P*, and P+, participating in the primary steps of photosynthesis were identified in the difference infrared spectra.
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118
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Banerjee S, Palit SK, Maiti S. Phosphorus containing polymers. Part 5. Polyazoxyphosphonate. Colloid Polym Sci 1994. [DOI: 10.1007/bf00657771] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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119
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Maiti S, Cowen BR, Diller R, Iannone M, Moser CC, Dutton PL, Hochstrasser RM. Picosecond infrared studies of the dynamics of the photosynthetic reaction center. Proc Natl Acad Sci U S A 1993; 90:5247-51. [PMID: 8506373 PMCID: PMC46693 DOI: 10.1073/pnas.90.11.5247] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The changes in the vibrational transitions of the protein and redox cofactors of the photosynthetic reaction center were examined by picosecond infrared spectroscopy. The spectra in the vibrational mid-infrared region (1800-1550 cm-1) of hydrated and partially dehydrated reaction centers were investigated from 50 ps to 4 ns after photoinitiation of the electron transfer. Features in the infrared difference spectra were identified with both protein and redox cofactor vibrational modes and correlated with electron transfer events whose kinetics were measured in the infrared and visible regions. The observed protein response is confined to a few amide I transitions (1644 cm-1, 1661 cm-1, 1665 cm-1) and carboxylic residues (1727 cm-1). About 85% of the observed signal corresponded to alterations in the cofactor-associated ester and keto carbonyls. The amide I and carboxylic transitions appeared prior to 50 ps, suggesting that the primary electron transfer event is coupled with a specific piece of the protein backbone and to glutamic or aspartic residues nearby the special pair. Infrared absorption changes accompanying bacteriochlorophyll-dimer cation formation dominated the signal at all times investigated. Infrared spectral changes observed in hydrated and partially dehydrated reaction centers were distinctly different; a band at 1665 cm-1 with a spectral width of 6 cm-1 in the hydrated protein, corresponding to a protein amide I bleach, was not present in the dehydrated film. These differences are discussed in terms of the markedly different electron transfer kinetics observed in the presence of water.
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120
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Diller R, Iannone M, Cowen BR, Maiti S, Bogomolni RA, Hochstrasser RM. Picosecond dynamics of bacteriorhodopsin, probed by time-resolved infrared spectroscopy. Biochemistry 1992; 31:5567-72. [PMID: 1610802 DOI: 10.1021/bi00139a020] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The photoinduced reaction cycle of bacteriorhodopsin (BR) has been studied by means of a recently developed picosecond infrared spectroscopic method at ambient temperature. BR - K difference spectra between 1560 and 1700 cm-1 have been recorded at delay times from 100 ps to 14 ns. The spectrum remains unchanged during this period. The negative difference OD band at 1660 cm-1 indicates the peptide backbone responds within 50 ps. A survey in the region of carboxylic side chain absorption around 1740 cm-1 reveals that perturbations of those groups, present in low-temperature FTIR spectra, are not observable within 10 ns, suggesting a slow conformational change.
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121
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Lannone M, Cowen BR, Diller R, Maiti S, Hochstrasser RM. High-repetition-rate infrared-pump, infrared-probe spectrometer. APPLIED OPTICS 1991; 30:5247-5249. [PMID: 20717353 DOI: 10.1364/ao.30.005247] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
A method for generating two independently tunable 25-ps infrared pulses at 500 Hz was demonstrated. The apparatus is based on two dye lasers, a regenerative amplifier, and two lithium iodate optical-parametric amplifiers. Using the pump-probe technique, we measured the lifetime of the excited vibrational-state absorption of tungsten hexacarbonyl in solution.
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Harel J, Daigle F, Maiti S, Désautels C, Labigne A, Fairbrother JM. Occurrence of pap-, sfa-, and afa-related sequences among F165-positive Escherichia coli from diseased animals. FEMS Microbiol Lett 1991; 66:177-82. [PMID: 1682206 DOI: 10.1016/0378-1097(91)90329-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
A total of 160 Escherichia coli positive for F165 fimbrial antigen and isolated from diarrheic and septicemic animals, were examined for the presence of the pap, afa, and sfa/foc operons or related nucleotide sequences using colony hybridization. Most isolates shared DNA sequences with the pap operon sequences alone or in association with afa or sfa. Thus, our results indicate that F165-positive E. coli from diseased animals share DNA sequences with operons coding for adhesins important in human extra-intestinal disease and that multiple adhesin systems are often found in single isolates. However, 20% of the F165-positive isolates did not show any homology with the probes representing the three adhesin systems, suggesting that one of the operons responsible for F165 production could be different from the pap, sfa/foc, and afa operons.
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Rahman MS, Pal U, Choudhury AK, Maiti S. New conducting polymers, 3. Doping, stability, electrical, and optical characteristics of poly-(P-phenylphosphoethynediyl). Colloid Polym Sci 1991. [DOI: 10.1007/bf00659911] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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124
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Maiti S, Das B, Mandal NC. Isolation and preliminary characterization of Escherichia coli mutants resistant to lethal action of the bacteriophage lambda P gene. Virology 1991; 182:351-2. [PMID: 1827225 DOI: 10.1016/0042-6822(91)90679-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Both spontaneous and NTG-induced mutants of Escherichia coli 594 insensitive to the lethal action of lambda P gene were isolated and called rpl (resistant to P lethality). These mutants were of two types, showing different phenotypes. On type I rpl mutants, lambda cl- and lambda v1v3 did not plate, while lambda vir, lambda cl- c17, lambda imm434, and lambda imm21 did; plasmid pMR45 carrying the lambda P gene could not complement lambda imm21P- phage in type I mutants. On the other hand, the type II rpl mutants support the growth of all the above phages including lambda cl-. Neither type of rpl mutation affects growth of the bacteria.
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125
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Maiti S, Mukhopadhyay M, Mandal NC. Bacteriophage lambda P gene shows host killing which is not dependent on lambda DNA replication. Virology 1991; 182:324-35. [PMID: 1827224 DOI: 10.1016/0042-6822(91)90676-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Bacteriophage lambda, having a mutation replacing glycine by glutamic acid at the 48th codon of cro, kills the host under N- conditions; we call this the hk mutation. In lambda N-N-cl-hk phage-infected bacteria, the late gene R is expressed to a significant level, phage DNA synthesis occurs with better efficiency, and the Cro activity is around 20% less, all compared to those in lambda N-N-cl-hk(+)-infected bacteria. Segments of lambda DNA from the left of pR to the right of tR2, carrying cro, cII, O, P, and the genes of the nin5 region from the above hk and hk+ phages, were cloned in pBR322. Studies with these plasmids and their derivatives having one or more of the lambda genes deleted indicate that the hk mutation is lethal only when a functional P gene is also present. When expression of P from pR is elevated, due to the deletion of tR1, host killing also occurs without the hk mutation. We conclude that the higher levels of P protein, produced either (1) when cro has the hk mutation or (2) when tR1 is deleted, are lethal to the host. We also show that due to the hk mutation, the Cro protein becomes partially defective in its negative regulation at pR, resulting in the expression of P to a lethal level even in the absence of N protein-mediated antitermination. This P protein-induced host killing depends neither on lambda DNA replication nor on any other gene functions of the phage.
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Maiti S, Chatterjee G, Pal SN, Mukherjee DR. Benign cystic teratoma of the testis. JOURNAL OF THE INDIAN MEDICAL ASSOCIATION 1990; 88:287-8. [PMID: 2090686] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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127
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128
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Lalwani R, Maiti S, Mukherji S. Visible light induced DNA-protein crosslinking in DNA-histone complex and sarcoma-180 chromatin in the presence of methylene blue. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 1990; 7:57-73. [PMID: 2125075 DOI: 10.1016/1011-1344(90)85143-k] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Formation of DNA-protein cross-links by the action of visible light in the presence of methylene blue was studied in calf thymus DNA-calf thymus histone complex and sarcoma-180 chromatin. The extent of cross-link formation decreases with a decrease in the histone to DNA ratio in the DNA-histone complex. In chromatin, it is at a maximum (93%) at a dye to DNA nucleotide ratio (D/P ratio) of 0.04 and is appreciable even at a very low dye concentration (75% at a D/P ratio of 0.0033). Sepharose 4B-CL column chromatography indicates that methylene blue acts as a mediator in the cross-linking process, but not as a linker in the DNA-protein cross-link. Dodecylsulphate-polyacrylamide gel electrophoresis patterns reveal that both histone and non-histone proteins are involved in cross-linking, but to a varied extent. Competition experiments with ethidium bromide demonstrated the necessity of intercalative binding of methylene blue in the formation of DNA--protein cross-links. Viscometric studies in 2 M NaCl indicate that the compact structure of chromatin is stabilized by cross-linking.
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Maiti S, Bhattacharya KL. Further simplification of the general analysis of the intercalative drug-DNA interaction. INDIAN JOURNAL OF BIOCHEMISTRY & BIOPHYSICS 1989; 26:109-19. [PMID: 2777318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The application of McGhee and von Hippel's general equation [J. Mol. Biol., 86 (1974), 469-489, Eq. (15)] to the analysis of the interaction of intercalative drugs with DNA has been further simplified. The value of n can now be determined mathematically, using a simple function, and without any approximation. It is also established that the summation of squared deviation of (( (nu/c), nu)) points would be minimum for and only for the true set of (K,n,omega) of the interaction system. The method incorporating the simplification has been applied to determine the binding parameters of adriamycin-DNA interaction according to the above general equation.
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Wing RE, Maiti S, Doane WM. Effectiveness of Jet-Cooked Pearl Cornstarch as a Controlled Release Matrix. STARCH-STARKE 1987. [DOI: 10.1002/star.19870391205] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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131
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Maiti S, Bhattacharya KL. A simplified procedure for application of McGhee and Von Hippel's general equation: analysis of the intercalative drug-DNA interaction. INDIAN JOURNAL OF BIOCHEMISTRY & BIOPHYSICS 1986; 23:197-203. [PMID: 3570336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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132
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133
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Mandal B, Maiti S. Displacement polymerization—V. Synthesis and characterization of polyarylethers containing furoxan and furazan units. Eur Polym J 1986. [DOI: 10.1016/0014-3057(86)90005-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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134
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Khamrai A, Adhikari B, Maiti M, Maiti S. Polymerisation of dithiocarbamates by oxidative coupling using iodine as oxidant—I. Synthesis and characterisation. Eur Polym J 1986. [DOI: 10.1016/0014-3057(86)90217-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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135
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Mahato B, Shit S, Maiti S. New block copolymers—III. Synthesis, characterization and crosslinking studies of an (A-B)n type block copolymer. Eur Polym J 1985. [DOI: 10.1016/0014-3057(85)90177-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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136
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137
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Chatterjee U, Maiti S, Sengupta KK. Kinetics of Oxidation of Oxalic Acid by Hexachloroiridate (IV). Z PHYS CHEM 1980. [DOI: 10.1515/zpch-1980-01148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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138
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Maiti S, Ali KM, De D, Bera TK, Ghosh D, Paul S. A Comparative Study on Nutritional Status of Urban and Rural Early Adolescent School Girls of West Bengal, India. JOURNAL OF NEPAL PAEDIATRIC SOCIETY 1970. [DOI: 10.3126/jnps.v31i3.5352] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Objectives: Adolescents remain largely neglected and especially girl from a deprived section in our society. The present study is an attempt to evaluate the nutritional status of early adolescent school girl from rural and urban areas. The study was, therefore, carried out to determine and compare the nutritional status of adolescent girl attending urban and rural secondary schools in Paschim Medinipur district of West Bengal, India. Methods: Cross-sectional data based on anthropometric measurements (height, weight) was collected from 2545 girls aged 10 to 14 years attending Govt. approved schools in Kharagpur town and Dantan-II block. The nutritional status has been assessed with the help of some anthropometric indices. The weight and height were recorded for each girl, and converted to nutritional indices (weightfor- age, height-for-height, BMI-for-age Z-scores of the National Center for Health Statistics reference standrads). Results: The mean nutritional indices (underweight, stunting and thinness) were found to be much lower among the rural girl than urban girl. The overall prevalent rates of underweight, stunting and thinness were 27.9%, 32.5% and 20.2% respectively. In the rural area these were 35.4%, 35.7% and 26.3%, while in the urban they were 19.6%, 29.0% and 13.6% respectively. Conclusions: The present study shows that undernutrition constituted major health problems among early adolescent school girls in rural areas of India. Hence, the special emphases are needed to formulate various developmental and healthcare programmes for rural communities to prevent undernutrition. Key words: Nutritional status; Early Adolescent girls; Rural; Urban DOI: http://dx.doi.org/10.3126/jnps.v31i3.5352 J Nep Paedtr Soc 2011;31(3):169-174
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