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G D Hitchens

Publications and source records attributed to G D Hitchens.

10 recordsLinked to original sources
PubMed1998

Aflatoxicosis in turkey poults is prevented by treatment of naturally contaminated corn with ozone generated by electrolysis.

Previous studies have demonstrated that a novel source of ozone gas (O3) maybe used to chemically degrade numerous mycotoxins, including aflatoxin (AF) B1. Subsequent in vitro analyses demonstrated detoxification of AFB1, suggesting a potential method of remediate AF-contaminated grain. The objective of this study was to evaluate the capability of electrochemically produced ozone to degrade AFB1 in naturally contaminated whole kernel corn and confirm detoxification in turkey poults. Corn was procured from the southern coastal areas of Texas and HPLC revealed 1,220 +/- 73.3 ppb AFB1. Control and contaminated corn were treated for 92 h with O3 at 200 mg/min in 30 kg batches; greater than 95% reduction of AFB1 in contaminated corn was achieved. One-day-old female turkey poults were fed 1) control corn, 2) control corn + O3, 3) AFB1 corn, or 4) AFB1 corn + O3 mixed in rations (46% by wt.) and consumed ad libitum for 3 wk. When compared with controls, turkeys fed AFB1 corn had reduced body weight gain and relative liver weight, whereas turkeys fed control corn + O3 or AFB1 corn + O3 did not differ from controls. Furthermore, alterations in the majority of relative organ weight, liver discoloration, serum enzyme activity, hematological parameters, and blood chemistry caused by AFB1 were eliminated (no difference from controls) by treatment with O3. These data demonstrate that treatment of contaminated corn with electrochemically produced O3 provided protection against AFB1 in young turkey poults. It is important to note that treatment of control corn with O3 did not alter the performance of the turkey poults.

Animal Feed↗
PubMed1991

A new photocatalytic material based on algal cells.

Metallic platinum was deposited at surfaces of intracellular photosynthetic membranes of whole cells of a cyanobacterium (blue-green alga). The deposited platinum particles acted as a catalyst for generation of hydrogen from photosynthetic decomposition of water in the absence of other exogenous electron transfer agents. This technique represents a means of placing metal catalysts in contact with intracellular structures of microorganisms.

Catalysis↗
PubMed1984

On the effects of thiocyanate and venturicidin on respiration-driven proton translocation in Paracoccus denitrificans.

A fast-responding O2 electrode has been used to confirm and extend observations of a significant kinetic discrepancy between O2 reduction and consequent proton translocation in 'O2-pulse' experiments in intact cells of P. denitrificans. The permeant, chaotropic SCN- ion abolishes this discrepancy, and greatly increases the observable----H+/O ratio, to a value approaching its accepted, true, limiting stoichiometry. The observable H+ decay rates are very slow, particularly in the absence of SCN-. The submaximal----H+/O ratios observed in the absence of SCN- are essentially independent of the size of the O2 pulse, in a manner not easily explained by a delocalised chemiosmotic energy-coupling scheme. Osmotically active protoplasts of P. denitrificans do not show a significant kinetic discrepancy between O2 reduction and H+ translocation, even in the the absence of SCN-. However, the submaximal----H+/O ratios observed in the absence of SCN- are again essentially independent of the size of the O2 pulse. As in intact cells, the observable H+ decay rates are very slow. The energy-transfer inhibitor venturicidin causes a significant increase in the----H+/O ratio observed in protoplasts of P. denitrificans in the absence of SCN-; the decay kinetics of the H+ translocation process are also somewhat modified. Nevertheless, the----H+/O ratio observed in the presence of venturicidin is also independent of the size of the O2 pulse. This observation militates further against arguments in which (a) a non-ohmic leak of protons from the bulk aqueous phase might alone be the cause of the low----H+/O ratios observed in the absence of SCN-, and (b) in which there might be a delta p-dependent change ('redox slip') in the actual----H+/O ratio. It is concluded that the observable protonmotive activity of the respiratory chain of P. denitrificans in the absence of SCN- is directly influenced by the state of the H+-ATP synthetase in the cytoplasmic membrane of this organism. We are unable to explain the data in terms of a model in which the putative protonmotive force may be acting to affect the----H+/O ratio. The possibility is considered that the delocalised bulk-to-bulk phase membrane potential set up in response to protonmotive activity is energetically insignificant.

Cell Membrane↗
PubMed1983

Uncouplers can shuttle between localized energy-coupling sites during photophosphorylation by chromatophores of Rhodopseudomonas capsulata N22.

Two models of the action of uncoupler molecules in inhibiting photophosphorylation in bacterial chromatophores are considered: either uncoupler molecules shuttle rapidly between energy-coupling sites, or uncoupler molecules that are bound to particular sites in the chromatophores for a time that is comparable with the turnover time of the photophosphorylation apparatus may uncouple by a co-operative "substoichiometric' mechanism. It is found that the titre of uncoupler necessary to cause complete uncoupling is lowered if the rate of photophosphorylation is initially decreased by partially restricting electron flow with an appropriate titre of antimycin A. This result indicates that uncoupler molecules shuttle rapidly between energy coupling in which the energized intermediate between electron transport and phosphorylation is delocalized over the entire chromatophore membrane and those in which it is not. If the rate of photophosphorylation is partially restricted with the covalent H+-translocating ATP synthase inhibitor dicyclohexylcarbodi-imide, the titre of uncoupler necessary to effect complete inhibition of photophosphorylation is also decreased relative to that in which the covalent H+-ATP synthase inhibitor is absent. This important result appears to be inconsistent with models of electron-transport phosphorylation in which the "energized state' of the chromatophore membrane that is set up by electron transport and utilized in photophosphorylation is delocalized over the entire chromatophore membrane.

Antimycin A↗
PubMed1982

On the extent of localization of the energized membrane state in chromatophores from Rhodopseudomonas capsulata N22.

1. The principle of the double-inhibitor titration method for assessing competing models of electron transport phosphorylation is expounded. 2. This principle is applied to photophosphorylation by chromatophores from Rhodopseudomonas capsulata N22. 3. It is found that, in contrast to the predictions of the chemiosmotic coupling model, free energy transfer is confined to individual electron transport chain and ATP synthase complexes. 4. This conclusion is not weakened by arguments concerning, the degree of uncoupling in the native chromatophore preparation or the relative number of electron transport chain and ATP synthase complexes present. 5. Photophosphorylation is completely inhibited by the uncoupler SF 6847 at a concentration corresponding to 0.31 molecules per electron transport chain. 6. The apparent paradox is solved by the proposal, consistent with the available evidence on the mode of action of uncouplers, that uncoupler binding causes a co-operative conformation transition in the chromatophore membrane, which leads to uncoupling and which is not present in the absence of uncoupler.

Antimycin A↗
PubMed1982

Localized energy coupling during photophosphorylation by chromatophores of Rhodopseudomonas capsulata N22.

The principle of the dual inhibitor titration method for testing models of electron-transport phosphorylation is outlined, and the method is applied to the study of photophosphorylation in bacterial chromatophores. It is concluded that energy coupling is strictly localized in nature in this system, in the sense that free energy released by a particular electron-transport chain may be used only by a particular H+-ATP synthase. Dual inhibitor titrations using the uncoupler SF 6847 and the H+-ATP synthase inhibitor oligomycin indicate that uncouplers act by shuttling rapidly between the localized energy-coupling sites.

ATP Synthetase Complexes↗