A comparative developmental pattern of enzymes of carbon metabolism and pentose phosphate pathway in mungbean and lentil nodules

The activities of enzymes of pentose phosphate pathway (PPP) viz. glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase and carbon metabolism viz. phosphoenol pyruvate carboxylase, NADP- isocitrate dehydrogenase and NADP-malic enzyme were measured in the plant and bacteroid fractions of mungbean (ureide exporter) and lentil (amide exporter) nodules along with the developing roots for comparison. The enzymes of pentose phosphate pathway in legume cytosol had higher activities at a stage of maximum nitrogenase activity and higher sucrose metabolism. However, bacteroids had only limited capacity for this pathway. The specific activities of these enzymes were greater in ureide than in amide exporter. CO₂ fixation via higher activity of phosphoenolpyruvate carboxylase in the plant part of the nodules in lentil might have been due to the greater synthesis of four carbon amino acids for amide export. The peak of NADP-isocitrate dehydrogenase in both legumes coincided with the pentose phosphate pathway enzymes at the time of high rates of sucrose metabolism and nitrogen fixation. Higher activities of NADP-malic enzyme were obtained in mungbean than in the lentil nodules. These findings are consistent with the role of these enzymes in providing reductant (NADPH) and substrates for energy yielding metabolism of bacteroids and carbon skeletons for ammonia assimilation.     

Tetracycline resistance determinants from groups A to D vary in their ability to confer decreased accumulation of tetracycline derivatives by Escherichia coli

The ability of four genetically distinct plasmid-located tetracycline resistance determinants (TetA, B, C and D) to confer decreased accumulation of tetracycline and some of its analogues by Escherichia coli K12 was examined. Accumulation of oxytetracycline, tetracycline, demethylchlorotetracycline, 6-demethyl-6-deoxy-5-hydroxy-6-methylene-tetracycline, chlorotetracycline, doxycycline and 6-demethyl-6-deoxytetracycline was examined by fluorescence spectroscopy. The determinants varied in their ability to promote decreased accumulation of tetracyclines, defined as an R+/R- fluorescence ratio of less than 0.85. Plasmid pIP7 (TetA) caused reduced accumulation of only oxytetracycline, tetracycline and chlorotetracycline, but plasmid pDU301 (TetB) promoted reduced accumulation of all the compounds tested except 6-demethyl-6-deoxytetracycline. The TetC determinant of pBR322 caused decreased uptake of five derivatives, but not doxycycline or 6-demethyl-6-deoxytetracycline. Plasmid RA1 (TetD) encoded reduced accumulation of oxytetracycline, tetracycline, 6-demethyl-6-deoxy-5-hydroxy-6-methylenetetracycline and chlorotetracycline. In general, the resistance determinants were more efficient in promoting decreased accumulation of hydrophilic tetracyclines. These accumulation studies provide a satisfactory method for the phenotypic identification of Tet resistance determinants.     

Force Generation via β-Cardiac Myosin,Titin, and α-Actinin Drives Cardiac Sarcomere Assembly from Cell-Matrix Adhesions

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Arabidopsis HIPP27 is a host susceptibility gene for the beet cyst nematode Heterodera schachtii

Sedentary plant‐parasitic cyst nematodes are obligate biotrophs that infect the roots of their host plant. Their parasitism is based on the modification of root cells to form a hypermetabolic syncytium from which the nematodes draw their nutrients. The aim of this study was to identify nematode susceptibility genes in Arabidopsis thaliana and to characterize their roles in supporting the parasitism of Heterodera schachtii. By selecting genes that were most strongly upregulated in response to cyst nematode infection, we identified HIPP27 (HEAVY METAL‐ASSOCIATED ISOPRENYLATED PLANT PROTEIN 27) as a host susceptibility factor required for beet cyst nematode infection and development. Detailed expression analysis revealed that HIPP27 is a cytoplasmic protein and that HIPP27 is strongly expressed in leaves, young roots and nematode‐induced syncytia. Loss‐of‐function Arabidopsis hipp27 mutants exhibited severely reduced susceptibility to H. schachtii and abnormal starch accumulation in syncytial and peridermal plastids. Our results suggest that HIPP27 is a susceptibility gene in Arabidopsis whose loss of function reduces plant susceptibility to cyst nematode infection without increasing the susceptibility to other pathogens or negatively affecting the plant phenotype.     

Molecular modeling studies and anti-TB activity of trisubstituted indolizine analogues; molecular docking and dynamic inputs

A series of trisubstituted indolizine analogues has been designed as a result of a fragment-based approach to target the inhibition of mycobacterial enoyl-acyl carrier protein reductase. Anti-tuberculosis (TB) screening of the characterized compounds by a resazurin microplate assay method revealed that ethyl group at second position of indolizine nucleus exhibited activity against susceptible and multidrug-resistant strains of Mycobacterium tuberculosis at concentration of 5.5 and 11.3 μg/mL, respectively. A molecular docking study was also conducted to evaluate the stability of the active compounds, and compound with ethyl substitution at second position of indolizine nucleus showed the highest free binding energy of ΔG ?24.11 (kcal/mol), a low clash score of 3.04, and high lipo score of ?13.33. Indolizine analog with ethyl substitution at second position demonstrated Molecular Mechanics/Generalized Born Surface Area (?23.85 kcal/mol). Two molecular dynamics studies were computed (100 ps and 50 ns) to calculate the relationship between the potential and kinetic energies of the active anti-TB compound with time and temperature. The discovery of this lead may have a positive impact on anti-TB drug discovery.