Effects of food deprivation on the respiratory metabolism of Oxyrrhismarina

E ec s o ood dep i a ion on he espi a o y me abolism o Oxy his ma ina N. Osmaa,*, T. Packa da, M. Gómeza aBiological Oceanog aphy Labo a o y, Facul ad de Ciencias del Ma , Uni e sidad de las Palmas de G an Cana ia, Campus Uni e si a io de Ta i a. 35017. Las Palmas de G an Cana ia. Cana y Islands, Spain. * E–mail: nosma@beca ios.ulpgc.es INTRODUCTION The mic ohe e o oph Oxy his ma ina has been used ex ensi ely as a model o ganism o examine he esponses o he e o ophic lagella es o a a ie y o ac o s. He e, we ocused in he espi a o y me abolism. Respi a ion is he oxygen consump ion (RO2) ca alyzed by he enzymes o he espi a o y elec on ans e sys em (ETS). The ETS ans e s he elec ons om he educing equi alen s ha a e p oduced du ing he oxida ion o o ganic molecules o oxygen (Fig 1). Thus, he RO2 a e o an o ganism is ela ed o he ood a ailabili y. We ed O. ma ina wi h he c yp ophy a Rhodomonas salina and we elucida ed he a ia ion o he espi a ion a es in s a a ion. METHODS & RESULTS CONCLUSIONS I) Respi a ion dec eases du ing ood dep i a ion in O. ma ina. II) ETS ac i i y is cons an du ing ood dep i a ion in O. ma ina. III) Cell sizes inc eases du ing ood dep i a ion in O. ma ina (cannibalism?). IV) The R/ETS a io dec eases bo h du ing ood dep i a ion and wi h inc easing cell size in O. ma ina. Aknowledgemen s This esea ch, is unded by he Fo ma ion and Pe ec ion o he Resea che Pe sonal P og am o he Basque Coun y Go e nmen and by he EXZOME p ojec (CTM 2008 –01616/MAR) om he Spanish Science and Educa ion Minis y. Re e ences: Low y, O. H., N. J. Roseb ough, e al. (1951). "P o ein measu emen wi h he olin phenol eagen ." Jou nal o Biological Chemis y 193: 265 - 275. Packa d, T. T., E. Be dale , e al. (1996). "Oxygen consump ion in he ma ine bac e ium Pseudomonas nau ica p edic ed om ETS ac i i y and bisubs a e enzyme kine ics." Jou nal o Plank on Resea ch 18(10): 1819 –1835. Figu e 1. S uc u e o he Elec on T ans e Sys em (ETS) coupled wi h ene gy (ATP) o ma ion. START SAMPLING!! END SAMPLING!! 0 20 40 60 80 100 120 140 1 2 3 4 RHODOMONAS (Cell numbe x106/l) 0 5 10 15 20 25 30 35 0 20 40 60 80 100 120 140 1 3 5 7 9 11 13 15 17 PROTEIN (mgl-1) o CELL NUMBER (x106/l) RO2o ETS (nmol O2min-1l-1) I II III IV 1 3 5 7 9 11 13 15 17 TIME(days) PROTEIN ETS CELL NUMBER RESPIRATION Figu e 2. (A) Cell numbe decline o Rhodomonas salina in he cul u e due o he eeding by O. ma ina. The expe imen began when he algae concen a ion in he cul u e was negligible. (B) Time p o iles o he measu emen s aken e e y 2 days o p o ein, ETS, espi a ion and cell numbe o O. ma ina.The p o ein con en and he ETS ac i i y s ayed s able du ing he en i e expe imen while he espi a ion and he cell numbe dec eased mo e han 50 %in he i s nine days. Each measu emen ep esen s he mean o iplica e analyses (n =27). AB FEEDING!! Figu e 3. Time p o iles o : (A) speci ic espi a ion; (B) ETS ac i i y; and (C) p o ein con en pe cell o O. ma ina. The consump ion o O2pe cell dec eased du ing he expe imen while he ETS ac i i y and p o ein con en inc eased. Each measu emen ep esen s he mean o iplica e analyses (n=27). y = -0,0121x + 0,257 R² = 0,7623 0,0 0,1 0,2 0,3 0,4 0246810 12 14 16 18 RO2 (pmol O2h-1cell-1) TIME (days) y = 0,0407x + 0,102 R² = 0,7863 0,0 0,2 0,4 0,6 0,8 1,0 0 2 4 6 8 10 12 14 16 18 ETS (pmol O2h-1cell-1) TIME (days) y = 0,2105x + 1,2298 R² = 0,8857 0 1 2 3 4 5 6 7 8 0 2 4 6 8 10 12 14 16 18 P o ein (ng cell-1) TIME (days) y = -0,589ln(x) + 1,7285 R² = 0,9214 0 0,5 1 1,5 2 0246810 12 14 16 18 R/ETS TIME (Days) y = -1,194ln(x) + 1,8581 R² = 0,8795 0 0,5 1 1,5 2 1 2 3 4 5 R/ETS P o ein/cell (ng/cell) Figu e 4. (A) Time cou se o he espi a ion / ETS ac i i y a io du ing he expe imen . (B) Va ia ion o he R/ETS a io wi h cell speci ic p o ein (cell size). The R/ETS a io declined exponen ially as long as O. ma ina was s a ed (le ). The same beha iou in he a io occu ed as he cell size inc eased ( igh ). The da a show a Pea son co ela ion coe icien o -0,902 (n=9, p<0,01). BA ACB Oxy his ma ina. Rhodomonas salina. ALGAL CULTURING T iplica e cul u es o O. ma ina,a 22.5ºC and low i adiance. Fil e ed Samples ETS ac i i y Packa d e al (1996) *adding succina e P o ein Low y e al. (1951) In i o Samples Cell numbe Lugol (4%), Coun ing chambe Respi a ion Oxygen elec odes. ANALYTICAL METHODS MITOCHONDRIA