Further characterization of phosphoinositol kinase isolated from germinating mung bean seeds

Phosphoinositol kinase isolated and purified from germinating mung bean seeds has been further characterized. The rate of phosphorylation varies with different inositol phosphates and this is consistent with the K_m and V_max for each of the substrates. The phosphate transfer from ATP has been found to be mediated by a phosphoprotein intermediate. In a particular step of the reaction the immediate product of the reaction has been found to be most inhibitory, other products being less or non-inhibitory. The inhibition has been found to be competitive in nature. The K_is have been found to range between 0.6 and 1 × 10^?4 M. ADP also inhibited non-competitively with respect to IP₅. K_i for this has been found to be 2.3 × 10^?4 M. The purified enzyme migrated as a single protein band on polyacrylamide gel electrophoresis. In the presence of sodium dodecyl sulphate it is dissociated into 3 subunits in the ratio 1 : 1 : 1. The MW of the three subunits are approx. 86 000, 56 000 and 35 000. The MW of the enzyme has been found to be approx. 177 000.     

Differential effects of oligomycin on carotid chemoreceptor responses to O2 and CO2 in the cat

Effects of oligomycin on carotid chemoreceptor responses to O2 and CO2 were investigated using an in situ perfusion technique. Cats were anesthetized, paralyzed, and artificially ventilated. To avoid a possible reaction between an oligomycin-ethanol mixture and blood, we administered oligomycin to the carotid body via cell- and protein-free perfusate. Except for the perfusion periods, the carotid body received its own natural blood supply. Responses to O2, CO2, sodium cyanide, and nicotine of the same carotid chemoreceptor afferents were studied before and after each perfusion. An appropriate low dose of oligomycin completely blocked carotid chemoreceptor response to O2 while preserving the CO2 response. At the same time cyanide response was attenuated leaving nicotine response intact. Additional doses of oligomycin attenuated carotid chemoreceptor response to CO2 as well. Perfusion with a blank solution containing ethanol did not change the carotid body chemoreceptor responses. These effects of oligomycin on carotid chemoreceptor responses to O2 and CO2 were reversible, and restoration of the response to CO2 preceded that to O2. In addition, oligomycin administered into the blood with close intra-arterial injection produced similar differential blockade of O2 and CO2 chemoreception, preserving the nicotine and dopamine effects. This study confirmed the previous findings and provided new evidence showing that 1) the responses of carotid chemoreceptor to O2 and CO2 were separable by oligomycin due to the inhibition of oxidative phosphorylation and 2) the responses to nicotine and dopamine were intact even after blockade of O2 response.     

A profile of the members of FASEB societies: NIH awards, degrees, and institutional affiliations, 1999.

Data from the FASEB Directory of Members and NIH were used to develop a statistical profile of the members of FASEB Societies. For the U.S.-based scientists (exclusive of retired and student members), the most frequently reported degree was a research doctorate (69. 6%). A substantial fraction, however, reported medical degrees (19. 2%) or both research and medical degrees (8.0%). The majority of members of FASEB Societies listed academic affiliations in the directory. Industrial affiliations were reported, however, in 9.7% of the entries with smaller fractions listing associations with hospitals, independent research institutes, and government agencies. Just over one-fourth of the members of FASEB Societies were principal investigators on NIH research grants. These investigators received one-half of all NIH grants and nearly 60% of the RO1 grants.     

Root associated iron oxidizing bacteria increase phosphate nutrition and influence root to shoot partitioning of iron in tolerant plant Typha angustifolia

Aims

Typha angustifolia is a heavy metal tolerant plant that grows in a uranium mine tailings highly contaminated with iron. In this study three iron oxidizing microbes (FeOBs) isolated from Typha rhizoplane were investigated for their role in plant growth promotion (PGP). Their effect on iron nutrition in Typha under iron replete and excess condition was also evaluated.

Methods

The PGP activities of the FeOBs were studied by measuring their influence on plant growth. To investigate the mechanism of growth promotion their ability to solubilize phosphate, and to produce Indole acetic acid and siderophores were studied. The influence of the FeOBs on root to shoot partitioning of iron was tested by measuring total iron content in roots and shoots treated with microbes.

Results

The FeOBs were named as Paenibacillus cookii JGR8, (MTCC12002), Pseudomonas jaduguda JGR2 (LMG25820) and Bacillus megaterium JGR9 (MTCC12001). The siderophore producers, influenced iron accumulation in the plant root. Additionally P. pseudoalcaligenes JGR2 increased shoot iron content overcoming the root- shoot barrier that allows Typha to exclude metals from its shoot. Among the PGP mechanisms tested, ability to solubilize phosphate appeared to be most significant for increasing the plant biomass.

Conclusion

FeOBs that produce siderophore increased iron content in plant and therefore can be of immense biotechnological importance. However Biomass increase was directly correlated with increased phosphate acquisition and not with enhanced iron accumulation in Typha.