• Volume 7, Issue 1

      March 1985,   pages  1-73

    • Inhibition of thymidine kinase activity by hydroxyurea during highly and less proliferative regions of rat brain

      V Prabhakar Kalluri Subba Rao

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      Hydroxyurea, when injected intraperitoneally, exerted marked inhibition on the activity of thymidine kinase in 5 day old postnatal cerebellum and 15 day old embryonic cerebrum. However, it failed to show any sustained inhibition on thymidine kinase activity in 5 day old postnatal cerebrum. In this case, the marginal decrease of thymidine kinase activity noticed during early intervals reversed back to more than normal value at a later time interval. These results along with our earlier findings are taken to indicate the differential action of this drug on thymidine kinase activity in rapidly and slowly proliferating regions of rat brain

    • Binding site amino acid residues of jack fruit (artocarpus integrifolia) seed lectin: chemical modification and protein difference spectral studies

      P S Appukuttan Debkumar Basu

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      The effect of chemical modification of amino acid residues essential for sugar binding in the α-D-galactoside specific jack fruit (Artocarpus integrifolia) seed lectin and the protection of the residues by specific sugar from modification were studied. Citraconylation or maleylation of 75 % of its lysyl residues or acetylation of 70 % of the tyrosyl residues completely abolished sugar binding and agglutination without dissociation of subunits. 1-O-methyl α-D-galactoside could protect its essential lysyl and tyrosyl groups from modification. Tryptophan could not be detected in the protein. Difference absorption spectra on binding of the above sugar confirmed the role of tyrosine residues and showed an association constantK = 0.4 × 103 M−1. Data suggests that the lectin could be immobilized without any loss of sugar binding activity

    • Enumeration and structural assessment of peritoneal macrophages during progressive protein deficiency in rats

      U R Iyengar U K Vakil

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      The effects of protein malnutrition on responsiveness of macrophages to proteosepeptone stimulation and on their chemical composition were investigated. Relative number of resident macrophages in rat peritoneal cavity was reduced by about 50 % during 4 weeks on 3 % protein diet. Similarly, decreased migration capacity of the circulating macrophages to the peritoneal exudate in response to the stimulant, was observed in protein-fasted rat compared to that in the 20 % protein-fed group. Further, the chemical composition of the isolated elicited cells was determined. Total proteins, sugars, lipids and nucleic acids were significantly low in the cells isolated from protein-deficient animals, though the cell size was not affected. However, cholesterol: phospholipid molar ratios were distinctly higher than that in control and increased progressively in the 3 and 8 % protein-fed animals. The implications of these structural changes in macrophages on their functional capability are discussed

    • Interaction of non-intercalative drugs with DNA: Distamycin analogues

      Malini Rajagopalan Jayalekshmy Ayyer V Sasisekharan

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      Distamycin and netropsin are two oligopeptides which bind to DNA in a nonintercalative manner. Analogues of distamycin have been synthesized and their binding with poly d(A-T) studied using ultraviolet absorption spectroscopy. Preliminary biological activity tests on a gram positive bacteria using these analogues have also been carried out

    • Effect of cupric-isonicotinic acid hydrazide complex on normal and avian myeloblastosis virus-infected cells cultivatedin vitro

      M B Vasudevachari A Antony

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      The cupric complex of isonicotinic acid hydrazide was found to be nontoxic to normal yolk sac macrophages upto a concentration of 100 ΜM. At this concentration the complex did not significantly inhibit DNA, RNA or protein synthesis in these cells. The complex inhibited the avian myeloblastosis virus multiplication in these cells when added 0–4 h post-infection as demonstrated by the inhibition of both focus formation and expression of viral specific antigens. This inhibition was not observed when the complex was added 8 and 16 h after avian myeloblastosis virus infection. The studies carried out on avian myeloblastosis virus-transformed myeloblasts indicated that the complex had no effect on the colony (focus) formation. The results suggest that the complex inhibits the virus multiplication by interfering in an early event of viral growth cycle, possibly the process of reverse transcription

    • Isolation, characterization and mapping of temperature-sensitive mutants of mycobacteriophage I3

      Chanchal Sadhu Mohan lal Gope Krishna Sadhu K P Gopinathan

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      Eighteen temperature-sensitive mutants of mycobacteriophage I3 have been isolated and partially characterized. All the mutants were defective in vegetative replication. Based on temperature shift experiments with the temperature sensitive mutants, the thermosensitive phase of the phage development period has been characterized for each mutant. The genes have been mapped by recombination analysis. The early, continuous and middle genes seem to cluster on the genetic map

    • Complimentary DNA sequence data analysis of prokaryotic systems

      A S Kolaskar B V B Reddy

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      Complimentary DNA sequence data of Φ × 174, fd, f1, G4, Ml3, MS2, λ and T7 phages ofEscherichia coli are analysed at mono-, di-, tri- and tetranucleotide levels. Our analysis shows that, (i) mononucleotides have certain preferences to occur at specific positions X1, X2, X3 of codon, (ii) These nucleotides interact nonlinearly to form dinucleotide and this dinucleotide also interacts nonlinearely with a third nucleotide to form codon, (iii) However, nonlinear interactions are negligible at tetranucleotide level suggesting that, coding regions of complimentary DNA are Markov chains of order two. Trinucleotide potential values in three frames have suggested that, at least thirteen different trinucleotides can be used as a marker to locate coding regions in DNA of prokaryotes. (iv) Parallel paired codons are expressed in such a way that one of the codons in the pair expresses with high frequency while the other with low frequency. On the other hand the complimentary codon pairs express with small frequency difference, (v) In the synonymous codon groups, codon ending with T are found to express with more frequency

    • Nucleic acid reactive antibodies— specificities and applications

      T M Jacob C Srikumar

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      The specificities of nucleic acid reactive antibodies and their applications in cell biology and molecular biology are reviewed

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