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Detection and characterisation of NAD(P)H-diaphorase activity in Dictyostelium discoideum cells (Protozoa)
1Department of Earth Sciences, Environment and Life, University of Genova, Italy. amaroli@dipteris.unige.it
Abstract:
In Dictyostelium discoideum (D. discoideum), compounds generating nitric oxide (NO) inhibit its aggregation and differentiation without altering cyclic guanosine monophosphate (cGMP) production. They do it by preventing initiation of cyclic adenosine monophosphate (cAMP) pulses. Furthermore, these compounds stimulate adenosine diphosphate (ADP)-ribosylation of a 41 kDa cytosolic protein and regulate the glyceraldehyde-3-phospate dehydrogenase activity. Yet, although D. discoideum cells produce NO at a relatively constant rate at the onset of their developmental cycle, there is still no evidence of the presence of nitric oxide synthase (NOS) enzymes. In this work, we detect the nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) activity in D. discoideum and we characterise it by specific inhibitors and physical-chemical conditions that allegedly distinguish between NOS-related and -unrelated NADPH-d activity.
Insights
Nitric oxide (NO) inhibits Dictyostelium discoideum development by blocking cyclic adenosine monophosphate (cAMP) pulses. This study identifies nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) activity, potentially linked to nitric oxide synthase (NOS).
Area of Science:
- Cellular biology
- Developmental biology
- Biochemistry
Background:
- Nitric oxide (NO) inhibits Dictyostelium discoideum aggregation and differentiation by preventing cyclic adenosine monophosphate (cAMP) pulse initiation.
- NO-generating compounds also affect cyclic guanosine monophosphate (cGMP) production, adenosine diphosphate (ADP)-ribosylation, and glyceraldehyde-3-phosphate dehydrogenase activity.
- Despite endogenous NO production during development, the presence of nitric oxide synthase (NOS) enzymes in D. discoideum remains unconfirmed.
Purpose of the Study:
- To detect and characterize nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) activity in D. discoideum.
- To investigate whether the detected NADPH-d activity is related to NOS.
Main Methods:
- Detection of NADPH-d activity in D. discoideum.
- Characterization of NADPH-d activity using specific inhibitors.
- Analysis of NADPH-d activity under various physical-chemical conditions.
Main Results:
- NADPH-d activity was detected in D. discoideum.
- The activity was characterized using specific inhibitors and conditions to differentiate NOS-related from NOS-unrelated NADPH-d activity.
Conclusions:
- This study provides evidence for NADPH-d activity in D. discoideum.
- Further characterization is needed to determine if this activity is NOS-related and to elucidate the precise mechanisms of NO's role in D. discoideum development.
