Storage deterioration of maize having pre-harvest infection with Aspergillus flavus

Deteriorative changes during storage of two different lots of field-contaminated (by Aspergillus flavus ), equally matured and freshly harvested (from two different fields) maize grains of the same cultivar (Ganga) and genotype, and stored under the same natural atmospheric conditions prevailing in the store-house, were studied and compared. It was found that the rate and extent or grain deterioration were much less in lot-2 than in lot-1 which had relatively high pre-harvest internal fungal ( A. flavus ) load. However, the deteriorative changes of both the lots could be reduced when the initial A. flavus infection was completely eliminated. Furthermore, of these already contaminated lots, the kernels selected as free of such infection at harvest also suffered less deterioration during storage.     

Clinical and experimental mycotic keratitis caused by Aspergillus terreus and the effect of subconjunctival oxiconazole treatment in the animal model

Aspergillus terreus was isolated from a case of Keratomycosis. The patient, a 50 year old, female presented with a large corneal ulcer with hypopyon. The direct microscopic examination of the scrapings revealed hyaline, thin, septate and branched hyphae. In vitro some antimycotics (amphotericin B,5-fluorocytosine, oxiconazole, amorolfine and ketoconazole) were tested against A. terreus by agar dilution method. Ketoconazole with MIC of 3 gmg/ml after 7 days of incubation was most effective followed by oxiconazole (10g/ml). Experimental corneal ulcer was produced by injecting intralamellary 0.1 ml of the spore suspension containing 10×10₆ cfu/ml into the eyes of previously immunocompressed albino rabbits. Histopathologic examination showed infiltration and large destruction of the corneal stroma. Subconjunctival oxiconazole therapy exhibited complete cure. Based on our findings, a clinical evaluation of oxiconazole in human keratomycosis seems to be justified.     

DNA-binding properties of an adenovirus 289R E1A protein.

An adenovirus 2 289 amino acid (289R) E1A protein purified from Escherichia coli has been shown to interact with DNA by two independent methods. UV-crosslinking of complexes containing unmodified, uniformly 32P-labelled DNA and purified E1A protein induced efficient labelling of the protein with covalently attached oligonucleotides, indicating that the E1A protein itself contacts DNA. Discrete nucleoprotein species were also observed when E1A protein--DNA complexes were analysed by gel electrophoresis. Although the 289R E1A protein exhibited no significant binding to single-stranded DNA or to RNA, no evidence for its sequence-specific binding to double-stranded DNA was obtained with either assay. Identification of the sites of covalent attachment of 32P-labelled oligonucleotides by partial proteolysis of the crosslinked E1A protein indicated that the interaction of this protein with DNA is mediated via domain(s) in the C-terminal half of the protein. Such previously unrecognized DNA-binding activity is likely to contribute to the regulatory activities of this important adenoviral protein.     

β-Amylolytic activities ofEmericella nidulans (eidam) vuill

Summary Screening of fungal isolates led to selection of a strain ofEmericella nidulans 45 producing exocellular -amylase in a starch medium. Studies of dialysed enzyme and the formulation of the medium for the enzyme production are presented.     

A comparison of aberration distribution and cell-cycle progression in cells treated with bleomycin with those exposed to X-rays

The extent of cell-cycle delay and the frequency of aberrant metaphases induced by bleomycin (BLM) and X-rays have been compared at doses which produce similar frequencies of chromosome aberrations by the 2 clastogenic agents (BLM, 40 micrograms/ml and X-rays, 2 Gy) in muntjac lymphocytes. The frequency of aberrant metaphases was low in BLM-treated cells; however, the number of aberrations per metaphase was higher than in cells exposed to X-rays. Thus in contrast to their uniform sensitivity to X-rays, the lymphocytes showed differential sensitivity to BLM. This might be due to differences among the cells in their uptake of BLM and/or its action on the nuclear membrane-DNA complex. In spite of the total number of chromosome aberrations being similar to that induced by X-rays, BLM did not induce a significant delay in cell-cycle progression as observed in the case of X-rays. A possible explanation could be that the DNA damages being limited to fewer cells than in the case of X-irradiation, the BLM-treated cultures had more normal cells allowing faster progression and/or unlike X-rays BLM may not be causing other cellular damages in addition to DNA breaks.     

Mechanism of autoxidation of oxyhaemoglobin

Oxyhaemoglobins from erythrocytes of different animals including fish, amphibians, reptiles, birds, mammals and human beings have been isolated by ion-exchange chromatography over phosphocellulose and the comparative rates of autoxidation of oxyhaemoglobin studied. The mechanism of autoxidationin vitro has been elucidated using toad as well as human oxyhaemoglobin. Autoxidation is markedly inhibited by carbon monoxide as well as by anion ligands, namely, potassium cyanide, sodium azide and potassium thiocyanate. The inhibition by anions is in the same order as their strength as nucleophiles, indicating that it is the oxyhaemoglobin and not the ligand-bound deoxy species which undergoes autoxidation. The structure of oxyhaemoglobin is considered to be mainly and determination of the rate of autoxidation with or without using superoxide dismutase and catalase indicates that the initial process of autoxidation takes place by dissociation of to methaemoglobin and superoxide to the extent of 24%. The superoxide thus produced reattacks oxyhaemoglobin to produce further methaemoglobin and hydrogen peroxide. H₂O₂ is a major oxidant of oxyhaemoglobin producing methaemoglobin to the extent of 53%. A tentative mechanism of autoxidation showing the sequence of reactions involving superoxide, H₂O₂ and OH has been presented.     

Comparison of grip strength and isomeric endurance between the right and left hands of men and their relationship with age and other physical parameters.

Maximum handgrip strength and endurance of fatiguing isometric handgrip muscle contraction at 40% of maximum voluntary contraction of the dominant hand were assessed separately for both right and left hands of 99 right-handed men aged 7-73 years. Subjects below 10 years (n = 6) could not follow up the endurance test methods and were excluded. The relationship of handgrip strength and endurance with age and other physical parameters was also assessed. Maximum grip strength and endurance of fatiguing submaximal contraction of the right hand were significantly greater than that of the left hand for most age groups. Grip strength was positively correlated with age from 7-19 years (r = 0.94 for right and r = 0.89 for left) and was negatively correlated with age from 20-73 years (r = -0.74 right and r = -0.69 left). Grip strength was positively correlated with the weight (r = 0.86 right and r = 0.87 left), height (r = 0.88 right and r = 0.87 left) and body surface area (r = 0.9 for both) of the subjects. Endurance of contraction of both hands did not show any relationship with age, different physical parameters or grip strength of the subjects.     

Cell cycle dependent variation of calmodulin in Tetrahymena

The level of calmodulin (CaM), a ubiquitous calcium-binding protein of eukaryotic cells was determined at different phases of the cell cycle in a synchronized Tetrahymena population. It was found that the concentration of CaM at G1 was approximately half of the concentration of S and this 2 x G1 level of CaM was maintained through the G2 and M stages of the cell cycle. To ascertain the role of CaM in the initiation of DNA synthesis, the cells were treated with trifluoperazine (TFP), a CaM antagonist, and EGTA (Ca2+-chelator) at the G1/S boundary. It was found that DNA synthesis was inhibited in these drug-treated cells. The uptake of the nucleotide precursor was not affected in TFP and EGTA treated cells, thus excluding the possibility of alteration in the membrane transport properties. Treatment with TFP failed to inhibit the synchronous mitotic division in Tetrahymena. The existence of a variable content of CaM through the cell cycle of Tetrahymena was demonstrated, suggesting the possible involvement of this Ca2+-binding protein in the nuclear DNA replication process.     

Further novel amido sugars within the glycopeptidolipid antigens of Mycobacterium avium

The individual serovars of the Mycobacterium avium complex, a source of serious and persistent infections in individuals with underlying immune deficiencies, also present an extraordinary set of novel sugar epitopes as part of their type-specific glycopeptidolipid surface antigens. Californium desorption-mass spectrometry has been successfully applied to the holistic glycopeptidolipid antigen of M. avium serovar 12 and its per-O-acetyl derivative, to arrive at the following structure, of molecular mass 1876: (Sequence: see text). The pentasaccharide hapten, released as the tetraglycosyl alditol, was subjected to methylation analysis, absolute configurational analysis, 1H NMR and fast atom bombardment-mass spectrometry to arrive at the structure: 4-(2'-Hydroxy) propionamido-4,6-dideoxy-3-O-Me-Glcp (beta 1----3)-4-O-Me-L-Rhap (alpha 1----3)-L-Rhap (alpha 1----3)-L-Rhap (alpha 1----2)-6-deoxytalitol. Two-dimensional proton correlation spectroscopy was also applied to determine the configuration of the unique distal segment of the oligosaccharide unit. The significance of this structure in the context of the fully elucidated structures of the antigens from 12 of the 31-member M. avium complex is discussed.     

Molybdenum nutrition of isolates of four Aspergillus species

The molybdenum requirement for growth and conidial formation by Aspergillus flavus, A. terreus, and A. sulphureus was found to be 0.2 ppb, which was one-fifth that of an A. niger isolate. Molybdenum deficiency depressed growth, conidial formation, dry weight, soluble protein, and the specific activities of nitrate reductase, succinic dehydrogenase, and aconitase in all the isolates of Aspergillus studied, but the specific activities of catalase and peroxidase were depressed only in isolates of A. niger, A. terreus, and A. flavus. Also, molybdenum deficiency stimulated the specific activities of acid phosphatase and ribonuclease in the A. flavus isolate, although the specific activities of these enzymes decreased in other isolates. Eighteen hours after the addition of molybdenum (5 ppb) to molybdenum-deficient (0.02 ppb) cultures of A. niger, the specific activities of catalase, peroxidase and succinic dehydrogenase were restored in the absence of cycloheximide, while the specific activity of nitrate reductase was recovered even in the presence of the inhibitor. There was no effect on the specific activities of aconitase and acid phosphatase following the addition of molybdenum to molybdenum-deficient cultures of A. niger.