Mode of Infection of Ascochyta Blight of Chickpea Caused by Ascochyta rabiei

Process of infection and histological changes with Ascochyta blight of chickpea caused by A. rabiei (Pass.) Labr. were studied by light microscopy. Germ tubes from conidia of the fungus penetrate the stem tissue at the juncture of two epidermal cells and form subepidermal aggregates until the fourth day. On the sixth day, yellowing and necrotisation of host tissue coincides with formation of mature pycnidia. Fungus causes extensive damage to cellulosic cell walls of parenchymatous cortical and pith tissues in advance of invading hyphae indicating involvement of cell wall degrading enzymes. Lignified tissues, particularly xylem tracheary elements, remain intact.     

Biochemistry of terminal deoxynucleotidyltransferase. Identification and unity of ribo- and deoxyribonucleoside triphosphate binding site in terminal deoxynucleotidyltransferase

Terminal deoxynucleotidyltransferase is the only DNA polymerase that is strongly inhibited in the presence of ATP. We have labeled calf terminal deoxynucleotidyltransferase with [32P]ATP in order to identify its binding site in terminal deoxynucleotidyltransferase. The specificity of ATP cross-linking to terminal deoxynucleotidyltransferase is shown by the competitive inhibition of the overall cross-linking reaction by deoxynucleoside triphosphates, as well as the ATP analogs Ap4A and Ap5A. Tryptic peptide mapping of [32P]ATP-labeled enzyme revealed a peptide fraction that contained the majority of cross-linked ATP. The properties, chromatographic characteristics, amino acid composition, and sequence analysis of this peptide fraction were identical with those found associated with dTTP cross-linked terminal deoxynucleotidyl-transferase peptide (Pandey, V. N., and Modak, M. J. (1988a). J. Biol. Chem. 263, 3744-3751). The involvement of the same 2 cysteine residues in the crosslinking of both nucleotides further confirmed the unity of the ATP and dTTP binding domain that contains residues 224-237 in the primary amino acid sequence of calf terminal deoxynucleotidyltransferase.     

Determinants of breast-feeding and post-partum amenorrhoea in Orissa

A life table analysis is made of the duration of breast-feeding and post-partum amenorrhoea in Orissa, India, taking one variable at a time using data from a baseline survey of fertility and mortality (BSFM) conducted on the lines of the World Fertility Survey. Then a multivariate (proportional hazard) analysis showed that socioeconomic factors including residence, caste status and education influence the breast-feeding and post-partum amenorrhoea periods. There was no effect of maternal age on the length of breast-feeding, but mean length of post-partum amenorrhoea varied with age. The durations of breast-feeding and post-partum amenorrhoea are strongly related.     

Nuclear-magnetic-resonance investigation of the cooperative homodimeric hemoglobin from the mollusc Scapharca inaequivalvis. Molecular and electronic structure of the cyano-met derivative

The proton nuclear-magnetic-resonance spectra of the cyano-met complexes of the cooperative dimeric and tetrameric hemoglobins from the mollusk Scapharca inaequivalvis have been investigated and compared to those of other structurally characterized oxygen binding hemoproteins. For these proteins, cooperativity is displayed even in the homodimer and preliminary X-ray structural data reveal an unusual back-to-front assembly with intersubunit contacts involving the EF helices [Royer, W. E., Love, W. E. + Fenderson, F. F. (1985) Nature (Lond.) 316, 277-280]. The pattern of hyperfine shifts is very similar for the dimer and tetramer chains, but distinctly different from those of previously characterized low-spin, ferric heme proteins. Individual heme resonances are identified by reconstituting the protein with specifically deuterated hemes. While the axial interactions involving the proximal and distal histidines are very similar to that in myoglobins and other hemoglobins, both the heme contact shift pattern and the amino acid dipolar shift pattern reflect a significantly reduced asymmetry. The decreased spread of the non-cordinated amino acid signals is interpreted in terms of a rotation of the magnetic axes relative to those in myoglobin or other hemoglobins, rather than a change in the magnetic anisotropy. The decreased spread of the heme methyl contact shifts supports this conclusion and is consistent with an orientation of the proximal histidine with the imidazole ring rotated by about 30-40 degrees relative to that in other structurally characterized proteins. Although resonances associated with a complex pattern of alternate heme orientations can be detected immediately after reconstitution of the protein, the isolated protein was found to exhibit insignificant equilibrium heme rotational disorder.     

Interaction of tyrosine with dissolved oxygen in solution and spectroscopic evidence for oscillations

Electronic absorption and fluorescence spectra of tyrosine have been studied, using aqueous solutions containing normal and excess amounts of dissolved oxygen, as a function of time. The absorption and fluorescence intensities are found to oscillate with time. Interaction between tyrosine and oxygen is appreciable but it seems that either the formation of a complex between the two molecules is not favoured, or the process of complexation is very slow and the complex weak.     

Differential effects of chronic endosulfan exposure to male rats in relation to hepatic drug metabolism and androgen biotransformation

Chronic endosulfan exposure in rats led to considerable increase in the activities of drug metabolizing enzymes, whereas it had inhibitory effect on the activities of enzymes involved in the androgen biotransformation. Endosulfan also produced a dose- and duration-dependent increase in microsomal lipid peroxidation. The alterations produced after shorter duration showed much variation with respect to the dose levels and exposure period of endosulfan studied. The above biochemical changes were reversed after endosulfan withdrawal.     

The oxidation of hemins by microsomal heme oxygenase. Structural requirements for the retention of substrate activity

The substrate specificity of microsomal heme oxygenase from rat liver was studied by introducing systematic structural changes in the array of substituents of the protohemin IX rings. Replacement of the vinyls by methyl groups resulted in hemins which were excellent substrates of the heme oxygenase. Replacement of the 4-vinyl group by a propionic acid chain (harderohemin), decreased substrate activity to 40%. The replacement of the vinyls by formyl residues strongly decreased substrate activity but the hemins were still substrates of heme oxygenase. The oxidation rates of Spirographis hemin and of 2,4-diformyldeuterohemin IX showed a time lag which was absent when isoSpirographis hemin was used as a substrate. This lag could be attributed to the formation of a transient hemiacetal between the 2-formyl group and the alpha-mesohydroxy residue. The isomeric protohemins I, XI, and XIV (Fischer's notation) were examined as possible substrates of microsomal heme oxygenase. In these protohemins the array of substituents of rings A and B was the same as in protohemin IX, but the methyl and propionic acid residues of rings C and D were at different positions from those of protohemin IX. None of them had substrate activity, indicating that the presence of two vicinal propionic acid side-chains at C6 and C7 was necessary for substrate activity. A hemin with only one propionic acid residue at C5 was not a substrate of the enzyme, either. When the propionic acid residues of protohemin IX were replaced by butyric acid residues, substrate activity decreased to 50% (as compared to protohemin IX), while when they were replaced by acetic acid residues, the substrate activity was entirely suppressed. The addition of dimethyl sulfoxide (25 mM) to the incubation mixture enhanced the oxidation of hemins with non-polar substituents in rings A and B by about 35%, while it was without effect on hemins with polar substituents in the same rings.     

Steroidal saponins of Costus speciosus

The structures of the saponins B and C have been established as gracillin and dioscin respectively. This is the first report of the occurrence of these     

Observations on reproduction in Scytonematopsis ghazipurensis Pandey & Mitra

Hydrobiologia - An interesting feature in the method of reproduction in Scytonematopsis ghazipurensis Pandey & Mitra has been described. A single cell or a few terminal cells together get...     

PHD3-mediated prolyl hydroxylation of nonmuscle actin impairs polymerization and cell motility

Actin filaments play an essential role in cell movement, and many posttranslational modifications regulate actin filament assembly. Here we report that prolyl hydroxylase 3 (PHD3) interacts with nonmuscle actin in human cells and catalyzes hydroxylation of actin at proline residues 307 and 322. Blocking PHD3 expression or catalytic activity by short hairpin RNA knockdown or pharmacological inhibition, respectively, decreased actin prolyl hydroxylation. PHD3 knockdown increased filamentous F-actin assembly, which was reversed by PHD3 overexpression. PHD3 knockdown increased cell velocity and migration distance. Inhibition of PHD3 prolyl hydroxylase activity by dimethyloxalylglycine also increased actin polymerization and cell migration. These data reveal a novel role for PHD3 as a negative regulator of cell motility through posttranslational modification of nonmuscle actins.