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Somerton, United Kingdom

Brickley M.R.,Harper Adams University College | Brickley M.R.,Oxford Brookes University | Brickley M.R.,Algal Cell Biology Research Group | Lawrie E.,Algal Cell Biology Research Group | And 3 more authors.
Pest Management Science | Year: 2012

Background: The aims of the present study were to validate a vital mitochondrial potentiometric staining method in Chlamydomonas reinhardtii and to utilise this method to examine the effect of the herbicide bromoxynil octanoate on mitochondrial potential in this species. A range of stains was investigated, including Rhodamine 123, DASPMI, Mitotracker Green, Mitotracker Orange and JC-1. Results: Rhodamine 123 (R123) had the highest utility of several candidate stains. Incubation with both 5 and 10 μM carbonyl cyanide 3-chlorophenylhydrazone caused significant fluorescence collapse [Dunn's post test (40.00, P < 0.01) and (45.49, P < 0.01) respectively], demonstrating that the R123 fluorescence reported mitochondrial potential. The effect of the herbicide bromoxynil octanoate was examined. Exposure to 0.1 mM of bromoxynil resulted in a significant increased mitochondrial fluorescence compared with the baseline (Mann-Whitney U = 222, P < 0.002), while concentrations of 1 mM and greater resulted in significant, almost complete loss of mitochondrial potential [mean fluorescence ratio = 1.193-1.289 (where a ratio of 1 represents total potential loss), Mann-Whitney U = 0.0, P < 0.001 (1 mM), 0.0, P < 0.0001 (2 mM), 0.0, P < 0.0001 (5 mM)]. EC 50 of the collapse in mitochondrial potential owing to bromoxynil incubation occurred at 0.72 mM, and the mean t 50 of bromoxynil octanoate action was 93 s. Conclusions: R123 is a sensitive potentiometric dye in C. reinhardtii that may find further use in investigations of both mitochondrial bioenergetics in plants and environmental toxicology. © 2011 Society of Chemical Industry.

Brickley M.R.,Harper Adams University College | Brickley M.R.,Oxford Brookes University | Brickley M.R.,Algal Cell Biology Research Group | Weise V.,Algal Cell Biology Research Group | And 2 more authors.
European Journal of Phycology | Year: 2010

Mougeotia sp. are widely distributed freshwater algae that have a characteristic chloroplast rotation response to incident light. he mechanics of the response have been elucidated, but no work regarding the bioenergetics of this process has been eported. The current study examined the morphology and movement dynamics of mitochondria in this alga. A novel method, tilizing DASPMI (dimethylaminostyrylmethylpyridiniumiodine) fluorescent dye, was developed to allow vital mitochondrial taining while avoiding sequestration of the dye by numerous cytoplasmic vesicles and then used to study mitochondrial ynamics. Mitochondria were elongated tubular structures that were significantly asymmetrically located in the perinuclear nd chloroplast edge regions. The mitochondria displayed small amplitude undirected movements with occasional highvelocity ursts of directional movement which were of greater magnitude. These latter movements were inhibited by a 30-min ncubation with latrunculin (50 μM), but were unaffected by incubation with colchicine (10 μM), indicating that the actin, but ot the microtubule cytoskeleton, is involved. The method used and the findings reported will allow research to be undertaken n the contribution of the chondriome to the chloroplast rotation response and other aspects of the bioenergetics of this organism. © 2010 British Phycological Society.

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