Jorge Calvo - Academia.edu (original) (raw)

Papers by Jorge Calvo

Research paper thumbnail of Fish muscle: the exceptional case of notothenioids

Fish Physiology and Biochemistry, 2008

Fish skeletal muscle is an excellent model for studying muscle structure and function, since it h... more Fish skeletal muscle is an excellent model for studying muscle structure and function, since it has a very well-structured arrangement with different fiber types segregated in the axial and pectoral fin muscles. The morphological and physiological characteristics of the different muscle fiber types have been studied in several teleost species. In fish muscle, fiber number and size varies with the species considered, limiting fish maximum final length due to constraints in metabolites and oxygen diffusion. In this work, we analyze some special characteristics of the skeletal muscle of the suborder Notothenioidei. They experienced an impressive radiation inside Antarctic waters, a stable and cold environment that could account for some of their special characteristics. The number of muscle fibers is very low, 12,700-164,000, in comparison to 550,000-1,200,000 in Salmo salar of similar sizes. The size of the fibers is very large, reaching 600 lm in diameter, while for example Salmo salar of similar sizes have fibers of 220 lm maximum diameter. Evolutionary adjustment in cell cycle length for working at low temperature has been shown in Harpagifer antarcticus (111 h at 0°C), when compared to the closely related sub-Antarctic species Harpagifer bispinis (150 h at 5°C). Maximum muscle fiber number decreases towards the more derived notothenioids, a trend that is more related to phylogeny than to geographical distribution (and hence water temperature), with values as low as 3,600 in Harpagifer bispinis. Mitochondria volume density in slow muscles of notothenioids is very high (reaching 0.56) and since maximal rates of substrate oxidation by mitochondria is not enhanced, at least in demersal notothenioids, volume density is the only means of overcoming thermal constraints on oxidative capacity. In brief, some characteristics of the muscles of notothenioids have an apparent phylogenetic component while others seem to be adaptations to low temperature.

Research paper thumbnail of Escape performance in the sub-Antarctic notothenioid fish Eleginops maclovinus

Polar Biology, 2002

Fast-start performance associated with escape behaviour was investigated in the sub-Antarctic not... more Fast-start performance associated with escape behaviour was investigated in the sub-Antarctic notothenioid Eleginops maclovinus from the Beagle Channel, Tierra del Fuego, Argentina (mean winter water temperature 4°C, mean summer water temperature 10°C). Fish acclimated to 8.5°C for 2 months were filmed at 2, 4, 6, 8 and 10°C. Escape responses were temperature dependent over the range of temperatures tested. Maximum lengthspecific velocity ðV V max Þ, maximum length-specific acceleration (Aˆm ax) and inertial power output (P iner) increased significantly with temperature. Q 10 values forV V max , Aˆm ax and P iner were 1.90, 3.27 and 8.90, respectively. Nondimensional curvature of the spine ðĉ cÞ also varied significantly with temperature, but was higher at low temperatures. The values ofĉ c were threefold lower than previously reported for Antarctic notothenioids and similar to the values for temperate species. The results indicate that the high values ofĉ c observed during escape behaviour in Antarctic notothenioids are not a universal feature of the suborder. A greater flexion of the body during fast starts is therefore a promising candidate for a specialised feature of behaviour linked to low-temperature performance.

Research paper thumbnail of Myogenic cell cycle duration in Harpagifer species with sub-Antarctic and Antarctic distributions: evidence for cold compensation

Journal of Experimental Biology, 2003

SUMMARY In teleosts, the proliferation of myogenic progenitor cells is required for muscle growth... more SUMMARY In teleosts, the proliferation of myogenic progenitor cells is required for muscle growth and nuclear turnover. We measured the cell cycle and S-phase duration of myogenic cells in the fast myotomal muscle of two closely related Harpagifer species by cumulative S-phase labelling with 5-bromo-2′-deoxyuridine (BrdU). Harpagifer antarcticus is a stenothermal species from the Antarctic peninsula (experiencing temperatures of -2°C to +1°C) and Harpagifer bispinis is a eurythermal species from the Beagle Channel, Tierra del Fuego (living at +4°C in winter and up to 11°C in summer). Specific growth rates in the adult stages studied were not significantly different from zero. Myogenic progenitor cells were identified using an antibody against c-met. Seventy-five percent of the c-met+ve cells were in a proliferative state in both species. Cell cycle time was 150 h at 5°C and 81.3 h at 10°C in H. bispinis (Q10=3.4). Cell cycle duration was 35% shorter in H. antarcticus at 0°C (111 h) ...

Research paper thumbnail of Influence of temperature, habitat and body mass on routine metabolic rates of Subantarctic teleosts

Scientia Marina, 2005

Subantarctic notothenioids are exposed to wider variations in temperature than those encountered ... more Subantarctic notothenioids are exposed to wider variations in temperature than those encountered in the Antarctic Ocean, the ancestral environment of the group. In this study the influence of temperature on the routine metabolic rate of Subantarctic teleosts was described and the results were compared with routine metabolic rates of species with different geographical distributions, exploring the concept of Metabolic Cold Adaptation (MCA). Oxygen consumption (VO 2R) was determined as an estimate of the routine metabolic rate for the following Subantarctic notothenioids: Paranotothenia magellanica, Patagonotothen sima, Eleginops maclovinus, Harpagifer bispinis and the eelpout Austrolycus depressiceps. In all studied species and tested temperatures, body mass and VO 2R showed a positive correlation. A drop in the temperature from 10 to 2ºC produced a significant reduction of VO 2R values with a Q 10 (10-2) varying between 4.69 and 9.54. VO 2R values were related to species habitat: pelagic species reached the highest values of VO 2R , while sluggish species had the lowest ones. We can conclude that the metabolic rates of these species of Subantarctic fish do not show MCA at the investigated temperatures.

Research paper thumbnail of Oxidative stress in gills of limpets from the Beagle Channel: comparison with limpets from the Antarctic

Scientia Marina, 2005

The aim of this work was to study the oxidative profile of gills of two limpet species (Nacella (... more The aim of this work was to study the oxidative profile of gills of two limpet species (Nacella (Patinigera) magellanica and Nacella (Patinigera) deaurata) (Gmelin, 1971) exposed to different environmental conditions. Due to the tidal characteristics of the Beagle Channel, N. magellanica are exposed to air twice daily for 3 to 5 hours each time, whereas N. deaurata are exposed to air for 3 hours only during spring tides. The different regime of exposure includes extreme temperatures under 0ºC during winter and more than 20°C in summer for N. magellanica, whereas N. deaurata are usually covered by more than 0.3 m of water at 4°C in winter and 11°C in summer. No significant differences were found between the two molluscs regarding the oxygen uptake, the content of α-tocopherol and β-carotene and the activities of the antioxidant enzymes catalase and superoxide dismutase. Lipid peroxidation in gills was estimated as the content of lipid radicals, assessed by electron paramagnetic resonance (EPR). Lipid radical content and total iron content were respectively 80.6 and 62% lower in N. magellanica than in N. deaurata. A typical EPR spectrum of ascorbyl radical in gills from both limpets was observed. Both the ascorbyl radical content and the ascorbyl radical content/ascorbate content ratio were significantly lower in N. magellanica than in N. deaurata. In the Antarctic Nacella concinna inhabits all levels of the littoral zone. Limpets at the highest level in the intertidal showed significantly increased activities of both catalase and superoxide dismutase as compared to their intertidal and subtidal relatives. Thus, it seems that Antarctic high intertidal conditions, involving regular exposure to air and presumably also thermal stress on sunny days during the Antarctic summer, cause a necessity for N. concinna to ward off higher oxygen radical species production by increasing its antioxidant defence. Taken as a whole, the data presented here indicate that coping with environmentally demanding conditions requires a complex adjustment of the physiological metabolic pathways to ensure survival by minimising intracellular damage.

Research paper thumbnail of Energy density of sub-Antarctic fishes from the Beagle Channel

Fish Physiology and Biochemistry, 2008

The energy density (ED) of nine species of sub-Antarctic fishes was estimated by calorimetry. The... more The energy density (ED) of nine species of sub-Antarctic fishes was estimated by calorimetry. The fish, seven notothenioids, one atherinopsid and one galaxiid, represents some of the more abundant species in the ichthyofauna of the Beagle Channel. Principalcomponents analysis (PCA) of the ED of the different organs/tissues indicated that PC 1 and PC 2 accounted for 87% of the variability. Separation along PC 1 corresponded to differences in muscle and liver energy densities whereas separation along PC 2 corresponded to differences in the ED of the gonads. Differences between species were significant except for P. sima. Inclusion of the gonadosomatic index (GSI) as an explanatory variable enabled us to establish the existence of energy transfer from muscle and liver to the gonads in ripe P. tessellata females. Total ED values varied between 4.21 and 6.26 kJ g-1 , the pelagic Odontesthes sp. being the species with the highest ED. A significant relationship between ED and muscle dry weight (DW M) was found for all the species except P. tessellata. These data are the first direct estimates of ED of fishes from the Beagle Channel.

Research paper thumbnail of The effect of seasonality on oxidative metabolism in Nacella (Patinigera) magellanica

Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2007

We studied the seasonal variation on aerobic metabolism and the response of oxidative stress para... more We studied the seasonal variation on aerobic metabolism and the response of oxidative stress parameters in the digestive glands of the subpolar limpet Nacella (P.) magellanica. Sampling was carried out from July (winter) 2002 to July 2003 in Beagle Channel, Tierra del Fuego, Argentina. Whole animal respiration rates increased in early spring as the animals spawned and remained elevated throughout summer and fall (winter: 0.09 ± 0.02 μmol O 2 h − 1 g − 1 ; summer: 0.31 ± 0.06 μmol O 2 h − 1 g − 1). Oxidative stress was assessed at the hydrophilic level as the ascorbyl radical content / ascorbate content ratio (A U / AH −). The A U / AH − ratio showed minimum values in winter (3.7 ± 0.2 10 − 5 AU) and increased in summer (18 ± 5 10 − 5 AU). A similar pattern was observed for lipid radical content (122 ± 29 pmol mg − 1 fresh mass [FW] in winter and 314 ± 45 pmol mg − 1 FW in summer), iron content (0.99 ± 0.07 and 2.7 ± 0.6 nmol mg − 1 FW in winter and summer, respectively) and catalase activity (2.9 ± 0.2 and 7 ± 1 U mg − 1 FW in winter and summer, respectively). Since nitrogen derived radicals are thought to be critically involved in oxidative metabolism in cells, nitric oxide content was measured and a significant difference in the content of the Fe-MGD-NO adduct in digestive glands from winter and summer animals was observed. Together, the data indicate that both oxygen and nitrogen radical generation rates in N. (P.) magellanica are strongly dependent on season.

Research paper thumbnail of Individual age and connective tissue lipofuscin in the hard clam Eurhomalea exalbida

Journal of Experimental Marine Biology and Ecology, 2002

In the hard clam Eurhomalea exalbida, autofluorescent granules were detected in high concentratio... more In the hard clam Eurhomalea exalbida, autofluorescent granules were detected in high concentrations in the connective tissue around the intestine and in other tissues. Autofluorescence combined with Sudan black B and PAS positive reactions suggested that these granules were lipofuscin-like. The concentration of this material in the connective tissue (CT) around the intestine was quantified by image analysis and expressed as total area fraction occupied by lipofuscin granules. Lipofuscin concentration was distinctly better related with individual age as determined from stable isotope-validated shell growth bands than with any morphometric parameter. This relationship was described best by a Gompertz model: Lipofuscin t = 24.79e À e À 0.029(Age t À 58.578) (N = 38; r nl 2 = 0.882). Age was predicted from lipofuscin CT concentration by a von Bertalanffy model: Age t = 68.00 (1 À e À 0.146(Lipofuscin t + 0.028)) 0.664 (N = 38; r nl 2 = 0.933). Our findings suggest that lipofuscin CT concentration in E. exalbida is a function of individual age. If this holds true for bivalves in general, lipofuscin may be a suitable proxy for age in species with less clear shell growth band patterns.

Research paper thumbnail of Somatic energy content and histological analysis of the gonads in Antarctic fish from the Scotia Arc

Research paper thumbnail of Spawning aggregations of Merluccius hubbsi, in Patagonian waters: evidence for a single stock?

Fisheries Research, 1993

From 1971, a small scale bottom trawl fishery has developed in the San Matías Gulf (41°–42° S; 64... more From 1971, a small scale bottom trawl fishery has developed in the San Matías Gulf (41°–42° S; 64°–65°W) of the Argentinean Sea, targeting the hake (Merluccius hubbsi Marini). The dynamics of a spawning aggregation of hake in the gulf were analyzed based on changes in sex ...

Research paper thumbnail of Specific testicular morphology in the atherinomorph Odontesthes nigricans (Richardson, 1848): a comparison with the sympatric species Odontesthes smitti (Lahille, 1929)

Journal of Applied Ichthyology, 2009

Research paper thumbnail of Reproductive cycle and energy content of Tawera gayi (Hupé 1854)(Bivalvia: Veneridae) at the southernmost limit of their distribution range

Journal of Shellfish Research, 2007

Research paper thumbnail of Seasonal changes in energy allocation to somatic and reproductive body components of the common cold temperature sea urchin Loxechinus albus in a Sub- …

Polar Biology, 2008

... Loxechinus albus in a Sub-Antarctic environment Analía F. Pérez · Elba Morriconi · Claudia Bo... more ... Loxechinus albus in a Sub-Antarctic environment Analía F. Pérez · Elba Morriconi · Claudia Boy · Jorge Calvo Received: 31 May 2007 / Revised: 15 September 2007 / Accepted: 18 September 2007 / Published online: 9 October 2007 © Springer-Verlag 2007 ...

Research paper thumbnail of Growth and productivity of the venerid bivalve Tawera gayi (Hupé, 1854) in the Bahía Ushuaia, Beagle Channel

Research paper thumbnail of Muscle growth in Polar fish: a study of <i>Harpagifer</i> species with sub-Antarctic and Antarctic distributions

Research paper thumbnail of An alternative method to freeze and transport biological tissue blocks for microscopy

Interciencia, Mar 1, 2008

Research paper thumbnail of Caracterizaci�n de los m�sculos de la nataci�n de dos notot�nidos subant�rticos

Research paper thumbnail of In vitro cardiac performance in the sub-antarctic notothenioids Eleginops maclovinus (subfamily eleginopinae), Paranotothenia magellanica, and Patagonotothen tessellata (subfamily nototheniinae)

Comparative Biochemistry and Physiology Part A: Physiology, 1997

Research paper thumbnail of Latitudinal variation in the abundance and oxidative capacities of muscle mitochondria in perciform fishes

The Journal of experimental biology, 1998

The abundance, distribution and oxidative capacities of mitochondria have been investigated in th... more The abundance, distribution and oxidative capacities of mitochondria have been investigated in the red pectoral fin adductor muscles of fish (Order Perciformes) that use a predominantly labriform style of swimming. Mediterranean Sea species from the families Labridae, Serranidae, Sparidae and Antarctic Nototheniidae and non-Antarctic Nototheniidae and Channichthyidae were studied. Sub-Antarctic species from the Beagle Channel, Tierra del Fuego, included the pelagic haemoglobin-less icefish (Champsocephalus esox) and the robalo (Eleginops maclovinus), which occurs as far north as 35 degrees S. In Champsocephalus esox, the mitochondrial volume density of red muscle was 0.51 and mitochondrial cristae surface density (43. 9 microm2 microm-3) was higher than reported for Antarctic icefishes. In the red-blooded, active pelagic or semi-pelagic species, mitochondrial volume density was within the range 0.27-0.33 regardless of habitat temperature. Amongst less active demersal species, mitoch...

Research paper thumbnail of Proliferation of myogenic progenitor cells following feeding in the sub-antarctic notothenioid fish Harpagifer bispinis

The Journal of experimental biology, 2003

Feeding metabolism and the activation of myogenic progenitor cells were investigated in the fast ... more Feeding metabolism and the activation of myogenic progenitor cells were investigated in the fast myotomal muscle of the sub-Antarctic fish Hapagifer bispinis acclimatized to either simulated summer (10 degrees C; 18 h:6 h light:dark) or simulated winter (5 degrees C; 6 h:18 h light:dark) conditions. Ingestion of a single meal equivalent to 10% and 15% of body mass in simulated winter and summer groups, respectively, resulted in an average 2.6-fold and 3.6-fold increase in oxygen consumption, declining to 75% of peak values after 63 h and 46 h. In fasted individuals, the number of myogenic progenitor cells, identified by the expression of c-met, was not significantly different between simulated summer and winter fish, representing 6.6% and 5.8% of total myonuclei, respectively. However, the number of cells expressing myogenin was higher whereas the expression of MyoD was lower in winter than in summer groups. The ingestion of a single meal under winter and summer treatment regimes re...

Research paper thumbnail of Fish muscle: the exceptional case of notothenioids

Fish Physiology and Biochemistry, 2008

Fish skeletal muscle is an excellent model for studying muscle structure and function, since it h... more Fish skeletal muscle is an excellent model for studying muscle structure and function, since it has a very well-structured arrangement with different fiber types segregated in the axial and pectoral fin muscles. The morphological and physiological characteristics of the different muscle fiber types have been studied in several teleost species. In fish muscle, fiber number and size varies with the species considered, limiting fish maximum final length due to constraints in metabolites and oxygen diffusion. In this work, we analyze some special characteristics of the skeletal muscle of the suborder Notothenioidei. They experienced an impressive radiation inside Antarctic waters, a stable and cold environment that could account for some of their special characteristics. The number of muscle fibers is very low, 12,700-164,000, in comparison to 550,000-1,200,000 in Salmo salar of similar sizes. The size of the fibers is very large, reaching 600 lm in diameter, while for example Salmo salar of similar sizes have fibers of 220 lm maximum diameter. Evolutionary adjustment in cell cycle length for working at low temperature has been shown in Harpagifer antarcticus (111 h at 0°C), when compared to the closely related sub-Antarctic species Harpagifer bispinis (150 h at 5°C). Maximum muscle fiber number decreases towards the more derived notothenioids, a trend that is more related to phylogeny than to geographical distribution (and hence water temperature), with values as low as 3,600 in Harpagifer bispinis. Mitochondria volume density in slow muscles of notothenioids is very high (reaching 0.56) and since maximal rates of substrate oxidation by mitochondria is not enhanced, at least in demersal notothenioids, volume density is the only means of overcoming thermal constraints on oxidative capacity. In brief, some characteristics of the muscles of notothenioids have an apparent phylogenetic component while others seem to be adaptations to low temperature.

Research paper thumbnail of Escape performance in the sub-Antarctic notothenioid fish Eleginops maclovinus

Polar Biology, 2002

Fast-start performance associated with escape behaviour was investigated in the sub-Antarctic not... more Fast-start performance associated with escape behaviour was investigated in the sub-Antarctic notothenioid Eleginops maclovinus from the Beagle Channel, Tierra del Fuego, Argentina (mean winter water temperature 4°C, mean summer water temperature 10°C). Fish acclimated to 8.5°C for 2 months were filmed at 2, 4, 6, 8 and 10°C. Escape responses were temperature dependent over the range of temperatures tested. Maximum lengthspecific velocity ðV V max Þ, maximum length-specific acceleration (Aˆm ax) and inertial power output (P iner) increased significantly with temperature. Q 10 values forV V max , Aˆm ax and P iner were 1.90, 3.27 and 8.90, respectively. Nondimensional curvature of the spine ðĉ cÞ also varied significantly with temperature, but was higher at low temperatures. The values ofĉ c were threefold lower than previously reported for Antarctic notothenioids and similar to the values for temperate species. The results indicate that the high values ofĉ c observed during escape behaviour in Antarctic notothenioids are not a universal feature of the suborder. A greater flexion of the body during fast starts is therefore a promising candidate for a specialised feature of behaviour linked to low-temperature performance.

Research paper thumbnail of Myogenic cell cycle duration in Harpagifer species with sub-Antarctic and Antarctic distributions: evidence for cold compensation

Journal of Experimental Biology, 2003

SUMMARY In teleosts, the proliferation of myogenic progenitor cells is required for muscle growth... more SUMMARY In teleosts, the proliferation of myogenic progenitor cells is required for muscle growth and nuclear turnover. We measured the cell cycle and S-phase duration of myogenic cells in the fast myotomal muscle of two closely related Harpagifer species by cumulative S-phase labelling with 5-bromo-2′-deoxyuridine (BrdU). Harpagifer antarcticus is a stenothermal species from the Antarctic peninsula (experiencing temperatures of -2°C to +1°C) and Harpagifer bispinis is a eurythermal species from the Beagle Channel, Tierra del Fuego (living at +4°C in winter and up to 11°C in summer). Specific growth rates in the adult stages studied were not significantly different from zero. Myogenic progenitor cells were identified using an antibody against c-met. Seventy-five percent of the c-met+ve cells were in a proliferative state in both species. Cell cycle time was 150 h at 5°C and 81.3 h at 10°C in H. bispinis (Q10=3.4). Cell cycle duration was 35% shorter in H. antarcticus at 0°C (111 h) ...

Research paper thumbnail of Influence of temperature, habitat and body mass on routine metabolic rates of Subantarctic teleosts

Scientia Marina, 2005

Subantarctic notothenioids are exposed to wider variations in temperature than those encountered ... more Subantarctic notothenioids are exposed to wider variations in temperature than those encountered in the Antarctic Ocean, the ancestral environment of the group. In this study the influence of temperature on the routine metabolic rate of Subantarctic teleosts was described and the results were compared with routine metabolic rates of species with different geographical distributions, exploring the concept of Metabolic Cold Adaptation (MCA). Oxygen consumption (VO 2R) was determined as an estimate of the routine metabolic rate for the following Subantarctic notothenioids: Paranotothenia magellanica, Patagonotothen sima, Eleginops maclovinus, Harpagifer bispinis and the eelpout Austrolycus depressiceps. In all studied species and tested temperatures, body mass and VO 2R showed a positive correlation. A drop in the temperature from 10 to 2ºC produced a significant reduction of VO 2R values with a Q 10 (10-2) varying between 4.69 and 9.54. VO 2R values were related to species habitat: pelagic species reached the highest values of VO 2R , while sluggish species had the lowest ones. We can conclude that the metabolic rates of these species of Subantarctic fish do not show MCA at the investigated temperatures.

Research paper thumbnail of Oxidative stress in gills of limpets from the Beagle Channel: comparison with limpets from the Antarctic

Scientia Marina, 2005

The aim of this work was to study the oxidative profile of gills of two limpet species (Nacella (... more The aim of this work was to study the oxidative profile of gills of two limpet species (Nacella (Patinigera) magellanica and Nacella (Patinigera) deaurata) (Gmelin, 1971) exposed to different environmental conditions. Due to the tidal characteristics of the Beagle Channel, N. magellanica are exposed to air twice daily for 3 to 5 hours each time, whereas N. deaurata are exposed to air for 3 hours only during spring tides. The different regime of exposure includes extreme temperatures under 0ºC during winter and more than 20°C in summer for N. magellanica, whereas N. deaurata are usually covered by more than 0.3 m of water at 4°C in winter and 11°C in summer. No significant differences were found between the two molluscs regarding the oxygen uptake, the content of α-tocopherol and β-carotene and the activities of the antioxidant enzymes catalase and superoxide dismutase. Lipid peroxidation in gills was estimated as the content of lipid radicals, assessed by electron paramagnetic resonance (EPR). Lipid radical content and total iron content were respectively 80.6 and 62% lower in N. magellanica than in N. deaurata. A typical EPR spectrum of ascorbyl radical in gills from both limpets was observed. Both the ascorbyl radical content and the ascorbyl radical content/ascorbate content ratio were significantly lower in N. magellanica than in N. deaurata. In the Antarctic Nacella concinna inhabits all levels of the littoral zone. Limpets at the highest level in the intertidal showed significantly increased activities of both catalase and superoxide dismutase as compared to their intertidal and subtidal relatives. Thus, it seems that Antarctic high intertidal conditions, involving regular exposure to air and presumably also thermal stress on sunny days during the Antarctic summer, cause a necessity for N. concinna to ward off higher oxygen radical species production by increasing its antioxidant defence. Taken as a whole, the data presented here indicate that coping with environmentally demanding conditions requires a complex adjustment of the physiological metabolic pathways to ensure survival by minimising intracellular damage.

Research paper thumbnail of Energy density of sub-Antarctic fishes from the Beagle Channel

Fish Physiology and Biochemistry, 2008

The energy density (ED) of nine species of sub-Antarctic fishes was estimated by calorimetry. The... more The energy density (ED) of nine species of sub-Antarctic fishes was estimated by calorimetry. The fish, seven notothenioids, one atherinopsid and one galaxiid, represents some of the more abundant species in the ichthyofauna of the Beagle Channel. Principalcomponents analysis (PCA) of the ED of the different organs/tissues indicated that PC 1 and PC 2 accounted for 87% of the variability. Separation along PC 1 corresponded to differences in muscle and liver energy densities whereas separation along PC 2 corresponded to differences in the ED of the gonads. Differences between species were significant except for P. sima. Inclusion of the gonadosomatic index (GSI) as an explanatory variable enabled us to establish the existence of energy transfer from muscle and liver to the gonads in ripe P. tessellata females. Total ED values varied between 4.21 and 6.26 kJ g-1 , the pelagic Odontesthes sp. being the species with the highest ED. A significant relationship between ED and muscle dry weight (DW M) was found for all the species except P. tessellata. These data are the first direct estimates of ED of fishes from the Beagle Channel.

Research paper thumbnail of The effect of seasonality on oxidative metabolism in Nacella (Patinigera) magellanica

Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2007

We studied the seasonal variation on aerobic metabolism and the response of oxidative stress para... more We studied the seasonal variation on aerobic metabolism and the response of oxidative stress parameters in the digestive glands of the subpolar limpet Nacella (P.) magellanica. Sampling was carried out from July (winter) 2002 to July 2003 in Beagle Channel, Tierra del Fuego, Argentina. Whole animal respiration rates increased in early spring as the animals spawned and remained elevated throughout summer and fall (winter: 0.09 ± 0.02 μmol O 2 h − 1 g − 1 ; summer: 0.31 ± 0.06 μmol O 2 h − 1 g − 1). Oxidative stress was assessed at the hydrophilic level as the ascorbyl radical content / ascorbate content ratio (A U / AH −). The A U / AH − ratio showed minimum values in winter (3.7 ± 0.2 10 − 5 AU) and increased in summer (18 ± 5 10 − 5 AU). A similar pattern was observed for lipid radical content (122 ± 29 pmol mg − 1 fresh mass [FW] in winter and 314 ± 45 pmol mg − 1 FW in summer), iron content (0.99 ± 0.07 and 2.7 ± 0.6 nmol mg − 1 FW in winter and summer, respectively) and catalase activity (2.9 ± 0.2 and 7 ± 1 U mg − 1 FW in winter and summer, respectively). Since nitrogen derived radicals are thought to be critically involved in oxidative metabolism in cells, nitric oxide content was measured and a significant difference in the content of the Fe-MGD-NO adduct in digestive glands from winter and summer animals was observed. Together, the data indicate that both oxygen and nitrogen radical generation rates in N. (P.) magellanica are strongly dependent on season.

Research paper thumbnail of Individual age and connective tissue lipofuscin in the hard clam Eurhomalea exalbida

Journal of Experimental Marine Biology and Ecology, 2002

In the hard clam Eurhomalea exalbida, autofluorescent granules were detected in high concentratio... more In the hard clam Eurhomalea exalbida, autofluorescent granules were detected in high concentrations in the connective tissue around the intestine and in other tissues. Autofluorescence combined with Sudan black B and PAS positive reactions suggested that these granules were lipofuscin-like. The concentration of this material in the connective tissue (CT) around the intestine was quantified by image analysis and expressed as total area fraction occupied by lipofuscin granules. Lipofuscin concentration was distinctly better related with individual age as determined from stable isotope-validated shell growth bands than with any morphometric parameter. This relationship was described best by a Gompertz model: Lipofuscin t = 24.79e À e À 0.029(Age t À 58.578) (N = 38; r nl 2 = 0.882). Age was predicted from lipofuscin CT concentration by a von Bertalanffy model: Age t = 68.00 (1 À e À 0.146(Lipofuscin t + 0.028)) 0.664 (N = 38; r nl 2 = 0.933). Our findings suggest that lipofuscin CT concentration in E. exalbida is a function of individual age. If this holds true for bivalves in general, lipofuscin may be a suitable proxy for age in species with less clear shell growth band patterns.

Research paper thumbnail of Somatic energy content and histological analysis of the gonads in Antarctic fish from the Scotia Arc

Research paper thumbnail of Spawning aggregations of Merluccius hubbsi, in Patagonian waters: evidence for a single stock?

Fisheries Research, 1993

From 1971, a small scale bottom trawl fishery has developed in the San Matías Gulf (41°–42° S; 64... more From 1971, a small scale bottom trawl fishery has developed in the San Matías Gulf (41°–42° S; 64°–65°W) of the Argentinean Sea, targeting the hake (Merluccius hubbsi Marini). The dynamics of a spawning aggregation of hake in the gulf were analyzed based on changes in sex ...

Research paper thumbnail of Specific testicular morphology in the atherinomorph Odontesthes nigricans (Richardson, 1848): a comparison with the sympatric species Odontesthes smitti (Lahille, 1929)

Journal of Applied Ichthyology, 2009

Research paper thumbnail of Reproductive cycle and energy content of Tawera gayi (Hupé 1854)(Bivalvia: Veneridae) at the southernmost limit of their distribution range

Journal of Shellfish Research, 2007

Research paper thumbnail of Seasonal changes in energy allocation to somatic and reproductive body components of the common cold temperature sea urchin Loxechinus albus in a Sub- …

Polar Biology, 2008

... Loxechinus albus in a Sub-Antarctic environment Analía F. Pérez · Elba Morriconi · Claudia Bo... more ... Loxechinus albus in a Sub-Antarctic environment Analía F. Pérez · Elba Morriconi · Claudia Boy · Jorge Calvo Received: 31 May 2007 / Revised: 15 September 2007 / Accepted: 18 September 2007 / Published online: 9 October 2007 © Springer-Verlag 2007 ...

Research paper thumbnail of Growth and productivity of the venerid bivalve Tawera gayi (Hupé, 1854) in the Bahía Ushuaia, Beagle Channel

Research paper thumbnail of Muscle growth in Polar fish: a study of <i>Harpagifer</i> species with sub-Antarctic and Antarctic distributions

Research paper thumbnail of An alternative method to freeze and transport biological tissue blocks for microscopy

Interciencia, Mar 1, 2008

Research paper thumbnail of Caracterizaci�n de los m�sculos de la nataci�n de dos notot�nidos subant�rticos

Research paper thumbnail of In vitro cardiac performance in the sub-antarctic notothenioids Eleginops maclovinus (subfamily eleginopinae), Paranotothenia magellanica, and Patagonotothen tessellata (subfamily nototheniinae)

Comparative Biochemistry and Physiology Part A: Physiology, 1997

Research paper thumbnail of Latitudinal variation in the abundance and oxidative capacities of muscle mitochondria in perciform fishes

The Journal of experimental biology, 1998

The abundance, distribution and oxidative capacities of mitochondria have been investigated in th... more The abundance, distribution and oxidative capacities of mitochondria have been investigated in the red pectoral fin adductor muscles of fish (Order Perciformes) that use a predominantly labriform style of swimming. Mediterranean Sea species from the families Labridae, Serranidae, Sparidae and Antarctic Nototheniidae and non-Antarctic Nototheniidae and Channichthyidae were studied. Sub-Antarctic species from the Beagle Channel, Tierra del Fuego, included the pelagic haemoglobin-less icefish (Champsocephalus esox) and the robalo (Eleginops maclovinus), which occurs as far north as 35 degrees S. In Champsocephalus esox, the mitochondrial volume density of red muscle was 0.51 and mitochondrial cristae surface density (43. 9 microm2 microm-3) was higher than reported for Antarctic icefishes. In the red-blooded, active pelagic or semi-pelagic species, mitochondrial volume density was within the range 0.27-0.33 regardless of habitat temperature. Amongst less active demersal species, mitoch...

Research paper thumbnail of Proliferation of myogenic progenitor cells following feeding in the sub-antarctic notothenioid fish Harpagifer bispinis

The Journal of experimental biology, 2003

Feeding metabolism and the activation of myogenic progenitor cells were investigated in the fast ... more Feeding metabolism and the activation of myogenic progenitor cells were investigated in the fast myotomal muscle of the sub-Antarctic fish Hapagifer bispinis acclimatized to either simulated summer (10 degrees C; 18 h:6 h light:dark) or simulated winter (5 degrees C; 6 h:18 h light:dark) conditions. Ingestion of a single meal equivalent to 10% and 15% of body mass in simulated winter and summer groups, respectively, resulted in an average 2.6-fold and 3.6-fold increase in oxygen consumption, declining to 75% of peak values after 63 h and 46 h. In fasted individuals, the number of myogenic progenitor cells, identified by the expression of c-met, was not significantly different between simulated summer and winter fish, representing 6.6% and 5.8% of total myonuclei, respectively. However, the number of cells expressing myogenin was higher whereas the expression of MyoD was lower in winter than in summer groups. The ingestion of a single meal under winter and summer treatment regimes re...