First evidence for the occurrence of cytochrome-o in a free-living nematode
1984; Elsevier BV; Volume: 78; Issue: 3 Linguagem: Inglês
10.1016/0305-0491(84)90126-3
ISSN0305-0491
Autores Tópico(s)Parasite Biology and Host Interactions
Resumo1. A reproducible method for the isolation of mitochondria of good integrity for the polarographic and spectrophotometric characterization of cytochromes from the small (< 1500 μm) free-living (model) nematode Aphelenchus avenae is described. 2. Of the substrates tested only α-Gp (RCR = 3.43 ± 0.19; ADP:O = 2.17 ± 0.07) and succinate (RCR = 2.62 ± 0.23; ADP:0 = 1.41 ± 0.06) were utilized to any significant extent. Lack of a response to exogenous NADH indicated good mitochondrial integrity. 3. The α-Gp and succinate induced state-3 respiration was little inhibited by high concentrations of antimycin A. Ascorbate/TMPD oxidase activity was only partially inhibited by 1 mM cyanide and azide. 4. Increasing concentrations of cyanide inhibited the state 3 succinate oxidation in a biphasic manner. 5. Difference spectra indicated the presence of a, b and c type cytochromes. 6. The occurrence of significantly greater b-type than c-type cytochromes was evident from the (reduced)-(oxidised) difference spectra (ratio 1.6:1.9). Of the b-types, about 80% constituted the CO-reactive b-types. 7. CO-difference spectra indicated the first evidence for the dual occurrence of cyt.o and cyt.a3 in a free-living (non-parasitic) nematode.
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