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Mitochondrial density as a parameter of physiological fitness in young and old Queen Scallops (Aequipecten opercularis)
Abstracts / Comparative Biochemistry and Physiology, Part A 146 (2007) S171–S188
respirometry following exposure of individuals to altered salinity at 5, 10, 15, 25 and 35‰ in both acute and 5-day trials. Presence or absence of sexual characteristics, overall length and weight were measured and analysed for any relationships with oxygen consumption. Preliminary results indicate that the average oxygen consumption rate increases more after 5 days of exposure to altered salinity than after 4 h, with the smallest individuals having the highest rates of oxygen consumption per mg wet weight, irrespective of salinity. doi:10.1016/j.cbpa.2007.01.389
A12.31 Visually guided obstacle avoidance in box jellyfish A. Garm, M. O'Connor, L. Parkefelt, D. Nilsson, (Lund University) Box jellyfish, cubomedusae, possess an impressive total of 24 eyes of four morphologically different types. Two of these eye types, called the upper and lower lens eyes, are camera type eyes with spherical fish-like lenses. Compared to other cnidarians, cubomedusae also have an elaborate behavioural repertoire, which seems to be predominantly visually guided. Still, positive phototaxis is the only described behaviour so far likely correlated with the eyes. We have explored the obstacle avoidance response of the Caribbean species Tripedalia cystophora and the Australian species, Chiropsella bronzie in a flow chamber. Our results show that obstacle avoidance is visually guided, and likely mediated by the lower lens eye. Avoidance behaviour is triggered when the obstacle takes up a certain angle in the visual field. The strength of the response is to some extent correlated with the intensity contrast between the obstacle and the surroundings (chamber walls). In the flow chamber Tripedalia cystophora displays a stronger obstacle avoidance response than Chiropsella bronzie since they have less contact with the obstacles. This correlates well with the differences in their habitats. Ablation experiments indicate that the efficiency of the response depends on a complete view of the surroundings. doi:10.1016/j.cbpa.2007.01.390
A12.32 Mitochondrial density as a parameter of physiological fitness in young and old Queen Scallops (Aequipecten opercularis) C. Gsottbauer, P. Steinbacher, W. Stoiber, A. Obermayer, J. Haslett, A. Sänger, (University of Salzburg, Austria); E. Philipp, (Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany) Queen Scallops (Aequipecten opercularis) exhibit a swimming escape response by “valve-clapping”. This is achieved by rapid
S181
contractions of the striated (fast) portion of the adductor muscle. It is known that swimming activity declines with scallop ageing. We propose that this is caused by changes of mitochondrial volume densities in the active muscle. We suggest that mitochondrial density decreases with increasing age thus reducing physiological fitness of the animal. Samples of the striated adductor muscle of two groups of Queen scallops, representing different age classes as measured by shell height (< 5.4 cm; > 6.0 cm) were dissected and prepared for electron microscopy. Quantitative analysis was performed on ultrathin sections. Based on randomised photosampling, 40 micrographs per muscle tissue sample were taken and the volume densities of mitochondria (and other cell components such as SR and myofibrils) were determined using stereological methods. Preliminary results, which form part of a larger study, indicate an age-correlated decrease in mitochondrial density of the adductor muscle. This correlation, when combined with the results of further physiological research that has demonstrated an age-dependent decrease in CS and COX activity of the adductor muscle, will provide information on changes of physiological stress response and increased predation risk with scallop age. doi:10.1016/j.cbpa.2007.01.391
A12.33 The role of cadherin2 in zebrafish cardiovascular development and cardiac regeneration B. Bagatto, E. Hissett, J. Francl, Q. Liu, (University of Akron) Cadherins are cell surface adhesion molecules that play important roles in the development and regeneration of vertebrate tissues and organs. We studied cadherin2 expression in developing zebrafish heart using in situ hybridization and immunocytochemical methods, and we found that cadherin2 was strongly expressed by the myocardium of the embryonic zebrafish. To gain insight into cadherin2 role in the formation and function of the heart, we analyzed cardiac differentiation and performance in a cadherin2 mutant, glass onion (glo). For regeneration studies, adult zebrafish were selected at random for heart resection surgery and recovered for 1- and 2-week periods in conditions of either normoxia or hypoxia. We found that the cadherin2 mutant had enlarged pericardial cavity, disorganized atrium and ventricle, and reduced expression of a ventricular specific marker vmhc. Individual myocardiocytes in the glo mutant embryos became round shaped and loosely aggregated. In vivo measurements of cardiac performance revealed that the mutant heart had significantly reduced heart rate, stroke volume and cardiac output compared to control embryos. Formation of the embryonic vascular system in the glo mutants was also affected. Cadherin2 is also upregulated following cardiac injury and continues to be upregulated during the repair process. Our results suggest that cadherin2 plays an essential role in zebrafish cardiovascular development and cardiac regeneration. Although the exact mechanisms remain unknown as to the formation of
respirometry following exposure of individuals to altered salinity at 5, 10, 15, 25 and 35‰ in both acute and 5-day trials. Presence or absence of sexual characteristics, overall length and weight were measured and analysed for any relationships with oxygen consumption. Preliminary results indicate that the average oxygen consumption rate increases more after 5 days of exposure to altered salinity than after 4 h, with the smallest individuals having the highest rates of oxygen consumption per mg wet weight, irrespective of salinity. doi:10.1016/j.cbpa.2007.01.389
A12.31 Visually guided obstacle avoidance in box jellyfish A. Garm, M. O'Connor, L. Parkefelt, D. Nilsson, (Lund University) Box jellyfish, cubomedusae, possess an impressive total of 24 eyes of four morphologically different types. Two of these eye types, called the upper and lower lens eyes, are camera type eyes with spherical fish-like lenses. Compared to other cnidarians, cubomedusae also have an elaborate behavioural repertoire, which seems to be predominantly visually guided. Still, positive phototaxis is the only described behaviour so far likely correlated with the eyes. We have explored the obstacle avoidance response of the Caribbean species Tripedalia cystophora and the Australian species, Chiropsella bronzie in a flow chamber. Our results show that obstacle avoidance is visually guided, and likely mediated by the lower lens eye. Avoidance behaviour is triggered when the obstacle takes up a certain angle in the visual field. The strength of the response is to some extent correlated with the intensity contrast between the obstacle and the surroundings (chamber walls). In the flow chamber Tripedalia cystophora displays a stronger obstacle avoidance response than Chiropsella bronzie since they have less contact with the obstacles. This correlates well with the differences in their habitats. Ablation experiments indicate that the efficiency of the response depends on a complete view of the surroundings. doi:10.1016/j.cbpa.2007.01.390
A12.32 Mitochondrial density as a parameter of physiological fitness in young and old Queen Scallops (Aequipecten opercularis) C. Gsottbauer, P. Steinbacher, W. Stoiber, A. Obermayer, J. Haslett, A. Sänger, (University of Salzburg, Austria); E. Philipp, (Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany) Queen Scallops (Aequipecten opercularis) exhibit a swimming escape response by “valve-clapping”. This is achieved by rapid
S181
contractions of the striated (fast) portion of the adductor muscle. It is known that swimming activity declines with scallop ageing. We propose that this is caused by changes of mitochondrial volume densities in the active muscle. We suggest that mitochondrial density decreases with increasing age thus reducing physiological fitness of the animal. Samples of the striated adductor muscle of two groups of Queen scallops, representing different age classes as measured by shell height (< 5.4 cm; > 6.0 cm) were dissected and prepared for electron microscopy. Quantitative analysis was performed on ultrathin sections. Based on randomised photosampling, 40 micrographs per muscle tissue sample were taken and the volume densities of mitochondria (and other cell components such as SR and myofibrils) were determined using stereological methods. Preliminary results, which form part of a larger study, indicate an age-correlated decrease in mitochondrial density of the adductor muscle. This correlation, when combined with the results of further physiological research that has demonstrated an age-dependent decrease in CS and COX activity of the adductor muscle, will provide information on changes of physiological stress response and increased predation risk with scallop age. doi:10.1016/j.cbpa.2007.01.391
A12.33 The role of cadherin2 in zebrafish cardiovascular development and cardiac regeneration B. Bagatto, E. Hissett, J. Francl, Q. Liu, (University of Akron) Cadherins are cell surface adhesion molecules that play important roles in the development and regeneration of vertebrate tissues and organs. We studied cadherin2 expression in developing zebrafish heart using in situ hybridization and immunocytochemical methods, and we found that cadherin2 was strongly expressed by the myocardium of the embryonic zebrafish. To gain insight into cadherin2 role in the formation and function of the heart, we analyzed cardiac differentiation and performance in a cadherin2 mutant, glass onion (glo). For regeneration studies, adult zebrafish were selected at random for heart resection surgery and recovered for 1- and 2-week periods in conditions of either normoxia or hypoxia. We found that the cadherin2 mutant had enlarged pericardial cavity, disorganized atrium and ventricle, and reduced expression of a ventricular specific marker vmhc. Individual myocardiocytes in the glo mutant embryos became round shaped and loosely aggregated. In vivo measurements of cardiac performance revealed that the mutant heart had significantly reduced heart rate, stroke volume and cardiac output compared to control embryos. Formation of the embryonic vascular system in the glo mutants was also affected. Cadherin2 is also upregulated following cardiac injury and continues to be upregulated during the repair process. Our results suggest that cadherin2 plays an essential role in zebrafish cardiovascular development and cardiac regeneration. Although the exact mechanisms remain unknown as to the formation of