Grouping of Micromonospora based on their cultural-morphologic features, antibiotic-sensitivity and formation of antibiotics

500 Micromonospora cultures were subdivided into nine groups on the basis of their cultural-morphological properties, the ability to produce antibiotics of certain chemical classes, and the sensitivity to 18 different antibiotics: aurantiaca (I), cinnamomea (II), cinnamomea-vinacea (III), cinnamomea-olivacea (IV), nigra (V), nigra-violacea (VI), lilacinescens (VII), coerulea (VIII) and brunnea (IX). Cultures belonging to groups I, II, III, V and VI are moderately sensitive to most of the antibiotics and often occur in natural substrates. Black Micromonospora cultures (groups V and VI) mostly produce aminoglycoside antibiotics while brown cultures (groups II and III) form macrolide antibiotics. Cultures belonging to groups IV, VII, VIII and IX have a higher sensitivity to most of the antibiotics and are rarely isolated from natural substrates. These cultures have a weak ability to produce antibiotics.     

Free radicals in health and disease

Molecular and Cellular Biochemistry -     

Occurrence of intramitochondrial Ca2+ granules in a hypertrophied heart exposed to adriamycin

Left ventricular hypertrophy was produced in rabbits by narrowing the abdominal aorta in the subdiaphragmatic region. Six weeks after the surgery, sham control as well as hypertrophied animals were treated with adriamycin. Myocardial cell damage resulting from a total cumulative dose of 5 mg/kg of adriamycin was seen only in hypertrophied hearts. Alterations in muscle cells of these hearts included prominent "contraction bands" and perinuclear edema. Mitochondria were characterized by swelling and accumulation of electron-opaque granules. Energy-dispersive x-ray analysis of the mitochondria revealed the presence of calcium in these granules. The study confirms that the hypertrophied heart is more vulnerable to adriamycin-induced cell damage and this may be due to an increased susceptibility of these hearts to the occurrence of Ca2+ overload in the cell.     

Oxidative stress and heart failure

Various abnormalities have been implicated in the transition of hypertrophy to heart failure but the exact mechanism is still unknown. Thus heart failure subsequent to hypertrophy remains a major clinical problem. Recently, oxidative stress has been suggested to play a critical role in the pathogenesis of heart failure. Here we describe antioxidant changes as well as their significance during hypertrophy and heart failure stages. Heart hypertrophy in rats and guinea pigs, in response to pressure over-load, is associated with an increase in antioxidant reserve and a decrease in oxidative stress. Hypertrophied rat hearts show increased tolerance for different oxidative stress conditions such as those imposed by free radicals, hypoxia-reoxygenation and ischemia-reperfusion. On the other hand, heart failure under acute as well as chronic conditions is associated with reduced antioxidant reserve and increased oxidative stress. The latter may have a causal role as suggested by the protection seen with antioxidant treatment in acute as well as in chronic heart failure. It is becoming increasingly apparent that, anytime the available antioxidant reserve in the cell becomes inadequate, myocardial dysfunction is imminent.     

Recognition of different pools of phosphatidylglycerol in intact cells and isolated membranes of Acholeplasma laidlawii by phospholipase A2.

Phospholipase A2 (EC 3.1.1.4) from pig pancreas hydrolyzes phosphatidylglycerol in intact cells and isolated membranes of Acholeplasma laidlawii. Complete degradation of phosphatidylglycerol in intact cells at 37 degrees C does not result in lysis as shown by the retention of intracellular K+ ions and the cytoplasmic glucose-6-phosphatase, as well as the inability to detect activity of membrane-bound intracellular NADH-oxidase. A. laidlawii was grown on linoleic acid. Phospholipase A2 treatment of these cells at 5 degrees C, at which temperature the lipids are still in the liquid-crystalline state, results in a rapid breakdown of 50% of the phosphatidylglycerol. The residual phosphatidylglycerol can be hydrolyzed only at elevated temperatures and at much smaller rates, depending strongly on the incubation temperature. When membranes isolated from these cells are incubated at 5 degrees C, 70% of the phosphatidylglycerol is hydrolyzed immediately. The hydrolysis of the residual 30% is again strongly temperature dependent. Cells were grown on palmitate, elaidate, or oleate to investigate possible effects of the lipid phase transition on the accessibility of phosphatidylglycerol for phospholipase A2. Under conditions in which all the lipid is in the solid state, no hydrolysis occurs. When solid and liquid-crystalline lipid phases coexist, a limited hydrolysis of phosphatidylglycerol can be observed. The results demonstrate the disposition of phosphatidylglycerol in three different pools in the membrane of A. laidlawii. Phospholipase A2 has been used to discriminate between these pools and to estimate the amount of phosphatidylglycerol which is present in the liquid-crystalline phase. The present data, however, do not allow a definite localization of the phosphatidylglycerol pools.     

Rock phosphate solubilization under alkaline conditions byAspergillus japonicus andA. foetidus

Aspergillus japonicus andA. foetidus were found to solubilize, five types of Indian rock phosphates at pH 8 and 9. Solubilization was higher in the presence of pyrite than in controls lacking either pyrite or fungal, inoculum. Both the aspergilli were found to be good pyrite solubilizers and could grow over a wide pH range. Solubilization of rock phosphates was the result of organic acid release and pyrite oxidation.     

Probucol promotes endogenous antioxidant reserve and confers protection against reperfusion injury

The present study examines whether a subchronic probucol treatment of rats offers protection against ischemia-reperfusion (IR) injury in isolated perfused hearts. Sprague-Dawley rats were treated every second day per week with probucol (cumulative dose 120 mg/kg body mass, i.p.) for 4 weeks. In the probucol group, baseline myocardial antioxidant enzyme, glutathione peroxidase (GSHPx), activity was increased (p<0.05), whereas superoxide dismutase (SOD) and catalase (CAT) activities were not changed. Baseline oxidative stress, as indicated by the myocardial lipid peroxidation, was less (p<0.05) in the probucol group. Isolated hearts were subjected to 60 min global I and 20 min R. Recovery of the contractile function in globally ischemic hearts upon reperfusion was 36% in untreated group and 74% in the probucol group. After IR, GSHPx and CAT activities were significantly (p<0.05) higher in the probucol group compared with the control group, whereas SOD did not change. Lipid peroxidation owing to IR was significantly less in the probocol group. These data suggest that probucol treatment improves endogenous antioxidant reserve and protects against increased oxidative stress following IR injury.     

Mechanisms of beneficial effects of probucol in adriamycin cardiomyopathy

Probucol, a lipid-lowering drug, has been shown to offer protection against adriamycin-induced cardiomyopathy. In order to define the mechanism of this protection, we examined changes in antioxidants and lipid peroxidation in hearts as well as lipids in hearts and plasma from rats treated with either adriamycin or adriamycin and probucol with appropriate controls. Any potential free radical quenching as well as growth inhibitory effects of probucol were also examined using Chinese hamster ovary (CHO) cells in culture. In animal model, adriamycin caused a significant depression in glutathione peroxidase and increased plasma and cardiac lipids as well as lipid peroxidation. Probucol treatment modulated adriamycin-induced cardiomyopathic changes and increased glutathione peroxidase and superoxide dismutase activities. In the presence of adriamycin under hypoxic conditions, formation of adriamycin semiquinone radical was detected by ESR. The cell growth in these cultures was also inhibited by adriamycin in a dose-dependent manner. Probucol had no effect on adriamycin-induced growth inhibition as well as formation of semiquinone radicals. It is proposed that probucol protection against adriamycin cardiomyopathy is mediated by increased antioxidants and lipid-lowering without any effect on free radical production.     

Microsoft Word macro for analysis of cytosine methylation by the bisulfite deamination reaction

Cytosine methylation at CpG dinucleotides is an important control mechanism in development, differentiation, and neoplasia. Bisulfite genomic sequencing and its modifications have been developed to examine methylation at these CpG dinucleotides. To use these methods, one has to (i) manually convert the sequence to that produced by bisulfite conversion and PCR amplification, taking into account that cytosine residues at CpG dinucleotides may or may not be converted depending on their methylation status, (ii) identify relevant restriction sites that may be used for methylation analysis, and (iii) conduct similar steps with the other DNA strand since the two strands of DNA are no longer complementary after bisulfite conversion. To automate these steps, we have developed a macro that can be used with Microsoft Word. This macro (i) converts genomic sequence to modified sequence that would result after bisulfite treatment facilitating primer design for bisulfite genomic sequencing and methylation-sensitive PCR assay and (ii) identifies restriction sites that are preserved in bisulfite-converted and PCR-amplified product only if cytosine residues at relevant CpG dinucleotides are methylated (and thereby not converted to uracil) in the genomic DNA.     

Antioxidant enzyme gene expression in congestive heart failure following mycardial infarction

Increased oxidative stress and reduction in antioxidant enzymes have been suggested to be involved in the pathophysiology of congestive heart failure subsequent to myocardial infarction (MI). The objective of the present study was to characterize changes in the mRNA abundance and protein levels for the enzymatic antioxidants, superoxide dismutase (SOD), glutathione peroxidase (GSHPx) and catalase during the sequelae of congestive heart failure in rats. MI was produced by the ligation of the left coronary artery and hearts from controls and 1, 4 and 16 week PMI groups were analyzed. Losartan treatment (2 mg/ml in drinking water, daily) was started at 4 weeks and continued for 12 weeks. The mRNA levels for SOD were reduced by about 40% at 1-week PMI, were near to the control levels at 4-week PMI and at 16 weeks PMI, the levels were reduced by about 73% below the controls. GSHPx mRNA levels remained unchanged at all time points. The mRNA levels for catalase remained unchanged at 1 and 4 weeks PMI and were significantly reduced by about 44% at 16 weeks PMI as compared to the controls. The protein levels for MnSOD, CuZnSOD, GSHPx at 1 and 16 weeks remained unchanged in treated and untreated PMI groups. However, the protein levels for catalase was significantly increased in the control and PMI groups treated with Losartan. It is concluded that changes in the SOD and catalase activities during severe heart failure correlated with changes in mRNA for these enzymes. The precise mechanism/s for the improvement in antioxidant reserve and protein levels after Losartan treatment is/are unclear at this time.