Publications (20)67.67 Total impact
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Article: The influence of depth, site exposure and season on the intensity of iceberg scouring in nearshore Antarctic waters
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ABSTRACT: Ice scour disturbance has a significant effect on the physical and biological characteristics of polar benthos. A series of grids, each consisting of 25 markers, were deployed along depth transects and replicated at two contrasting study sites at Adelaide Island, West Antarctic Peninsula. Markers were surveyed and replaced every 3months for 2years in order to assess the frequency and intensity of iceberg impacts. Depth, site, season and year were all highly significant factors influencing ice scouring frequency. We observed a high variation in the duration of winter fast ice between sites and years, which had a marked effect on ice scouring frequency. The ecological effects of the disturbance regime are likely to include depth zonation of benthic assemblages, patchiness of communities at varying stages of recovery and the near denudation of sessile fauna in the shallow subtidal.Polar Biology 04/2012; 30(6):769-779. · 1.66 Impact Factor -
Article: The HSP70 heat shock response in the Antarctic fish Harpagifer antarcticus
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ABSTRACT: Members of the HSP70 gene family comprising the constitutive (HSC70) and inducible (HSP70) genes, plus GRP78 (Glucose-regulated protein 78kDa) were surveyed for expression levels via Q-PCR after both an acute 2-h heat shock experiment and a time course assay in the Antarctic plunderfish Harpagifer antarcticus. In general, down regulation of all genes was observed during the course of the heat shock experiments. This thermally induced down regulation was particularly acute for the GRP78 gene, which at one time point was more than 100-fold down regulated. These results demonstrate the loss of the heat shock response in H. antarcticus, a basal member of the Notothenioidei. This finding is discussed with reference to the survival of Notothenioids during observed ocean warming and also the reorganisation of cellular protein mechanisms of species living in extreme environments.Polar Biology 04/2012; 31(2):171-180. · 1.66 Impact Factor -
Article: Lack of an HSP70 heat shock response in two Antarctic marine invertebrates
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ABSTRACT: Members of the HSP70 gene family comprising the inducible (HSP70) genes and GRP78 (glucose-regulated protein 78kDa) were identified in an Antarctic sea star (Odontaster validus) and an Antarctic gammarid (Paraceradocus gibber). These genes were surveyed for expression levels via Q-PCR after an acute 2-hour heat shock experiment in both animals and a time course assay in O. validus. No significant up-regulation was detected for any of the genes in either of the animals during the acute heat shock. The time course experiment in O. validus produced slightly different results with an initial down regulation in these genes at 2°C, but no significant up-regulation of the genes either at 2 or 6°C. Therefore, the classical heat shock response is absent in both species. The data is discussed in the context of the organisms’ thermal tolerance and the applicability of HSP70 to monitor thermal stress in Antarctic marine organisms.Polar Biology 07/2008; 31(9):1059-1065. · 1.66 Impact Factor -
Article: Ice scour disturbance in Antarctic waters.
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ABSTRACT: The West Antarctic Peninsula is one of the fastest warming regions on Earth, and, as a consequence, most maritime glaciers and ice shelves in the region have significantly retreated over the past few decades. We collected a multiyear data set on ice scouring frequency from Antarctica by using unique experimental markers and scuba diving surveys. We show that the annual intensity of ice scouring is negatively correlated with the duration of the winter fast ice season. Because fast ice extent and duration is currently in decline in the region after recent rapid warming, it is likely that marine benthic communities are set for even more scouring in the near future.Science 07/2008; 321(5887):371. · 31.20 Impact Factor -
Article: Hibernation in an antarctic fish: on ice for winter.
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ABSTRACT: Active metabolic suppression in anticipation of winter conditions has been demonstrated in species of mammals, birds, reptiles and amphibians, but not fish. This is because the reduction in metabolic rate in fish is directly proportional to the decrease in water temperature and they appear to be incapable of further suppressing their metabolic rate independently of temperature. However, the Antarctic fish (Notothenia coriiceps) is unusual because it undergoes winter metabolic suppression irrespective of water temperature. We assessed the seasonal ecological strategy by monitoring swimming activity, growth, feeding and heart rate (f(H)) in N. coriiceps as they free-ranged within sub-zero waters. The metabolic rate of wild fish was extrapolated from f(H )recordings, from oxygen consumption calibrations established in the laboratory prior to fish release. Throughout the summer months N. coriiceps spent a considerable proportion of its time foraging, resulting in a growth rate (G(w)) of 0.18 +/- 0.2% day(-1). In contrast, during winter much of the time was spent sedentary within a refuge and fish showed a net loss in G(w) (-0.05 +/- 0.05% day(-1)). Whilst inactive during winter, N. coriiceps displayed a very low f(H), reduced sensory and motor capabilities, and standard metabolic rate was one third lower than in summer. In a similar manner to other hibernating species, dormancy was interrupted with periodic arousals. These arousals, which lasted a few hours, occurred every 4-12 days. During arousal activity, f(H) and metabolism increased to summer levels. This endogenous suppression and activation of metabolic processes, independent of body temperature, demonstrates that N. coriiceps were effectively 'putting themselves on ice' during winter months until food resources improved. This study demonstrates that at least some fish species can enter a dormant state similar to hibernation that is not temperature driven and presumably provides seasonal energetic benefits.PLoS ONE 02/2008; 3(3):e1743. · 4.09 Impact Factor -
Article: Antarctic marine molluscs do have an HSP70 heat shock response.
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ABSTRACT: The success of any organism depends not only on niche adaptation but also the ability to survive environmental perturbation from homeostasis, a situation generically described as stress. Although species-specific mechanisms to combat "stress" have been described, the production of heat shock proteins (HSPs), such as HSP70, is universally described across all taxa. Members of the HSP70 gene family comprising the constitutive (HSC70) and inducible (HSP70) members, plus GRP78 (glucose-regulated protein, 78 kDa), a related HSP70 family member, were cloned using degenerate polymerase chain reaction (PCR) from two evolutionary divergent Antarctic marine molluscs (Laternula elliptica and Nacella concinna), a bivalve and a gastropod, respectively. The expression of the HSP70 family members was surveyed via quantitative PCR after an acute 2-h heat shock experiment. Both species demonstrated significant up-regulation of HSP70 gene expression in response to increased temperatures. However, the temperature level at which these responses were induced varied with the species (+6-8 degrees C for L. elliptica and +8-10 degrees C for N. concinna) compared to their natural environmental temperature). L. elliptica also showed tissue-specific expression of the genes under study. Previous work on Antarctic fish has shown that they lack the classical heat shock response, with the inducible form of HSP70 being permanently expressed with an expression not further induced under higher temperature regimes. This study shows that this is not the case for other Antarctic animals, with the two molluscs showing an inducible heat shock response, at a level probably set during their temperate evolutionary past.Cell Stress and Chaperones 02/2008; 13(1):39-49. · 3.01 Impact Factor -
Article: Low heat-shock thresholds in wild Antarctic inter-tidal limpets (Nacella concinna).
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ABSTRACT: Heat shock proteins (HSPs) are a family of genes classically used to measure levels of organism stress. We have previously identified two HSP70 genes (HSP70A and HSP70B) in sub-tidal populations of the Antarctic limpet (Nacella concinna). These genes are up-regulated in response to increased seawater temperatures of 15 degrees C or more during acute heat shock experiments, temperatures that have very little basis when considering the current Antarctic ecology of these animals. Therefore, the question was posed as to whether these animals could express HSP70 genes when subjected to more complex environmental conditions, such as those that occur in the inter-tidal. Inter-tidal limpets were collected on three occasions in different weather conditions at South Cove, Rothera Point, over a complete tidal cycle, and the expression levels of the HSP70 genes were measured. Both genes showed relative up-regulation of gene expression over the period of the tidal cycle. The average foot temperature of these animals was 3.3 degrees C, far below that of the acute heat shock experiments. These experiments demonstrate that the temperature and expression levels of HSP production in wild animals cannot be accurately extrapolated from experimentally induced treatments, especially when considering the complexity of stressors in the natural environment. However, experimental manipulation can provide molecular markers for identifying stress in Antarctic molluscs, provided it is accompanied by environmental validation, as demonstrated here.Cell Stress and Chaperones 02/2008; 13(1):51-8. · 3.01 Impact Factor -
Article: The influence of ice scour on benthic communities at three contrasting sites at Adelaide Island, Antarctica
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ABSTRACT: Abstract Ice scouring is a key structuring force acting on high latitude shallow benthic communities. Despite its importance, detailed studies of scoured communities are still rare. Here we report the ecological effects of 12 iceberg impacts, across three contrasting study sites, at Adelaide Island, West Antarctic Peninsula. Grounded icebergs were marked with GPS and the newly formed scours (at 10–17 m depth) were sampled within 20 days of formation. Comparisons between scoured and adjacent unscoured assemblages were made using measures of abundance, biomass, taxon richness and the relative abundance of secondary consumers. Ice scouring was catastrophic at all sites, despite differences in substratum type, exposure and background community. Compared with undisturbed areas, scour assemblages were 95% lower in mean macrofaunal abundance and 75.9% lower in species richness. There was no general trend across all sites of ice scouring selecting for secondary consumers. The echinoid Sterechinus neumayeri and bivalve mollusc Mysella charcoti were highly abundant in undisturbed areas and were the biggest contributors to the observed differences between scours and undisturbed areas.Austral Ecology 11/2007; 32(8):878 - 888. · 1.82 Impact Factor -
Article: Growth in the slow lane: protein metabolism in the Antarctic limpet Nacella concinna (Strebel 1908).
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ABSTRACT: Growth rates in Antarctic ectotherms are generally considered to be low in comparison to temperate and tropical species. Food consumption plays a major role in determining animal growth rates, but once food is ingested soft tissue growth rates are largely determined by the protein synthesis retention efficiency (PSRE), a measure of the efficiency with which proteins are synthesised and retained as protein growth. The effect of water temperatures on the PSRE of polar organisms has not previously been investigated, and it is possible that reduced PSRE at polar water temperatures may at least partially explain low growth rates in Antarctic organisms. We also currently lack any information on the potential effects of predicted increases in seawater temperatures on protein metabolism in Antarctic ectotherms. We have measured seasonal protein synthesis, degradation and growth rates in free-ranging Antarctic limpets (Nacella concinna), together with protein synthesis rates at temperatures ranging between -1.5 degrees C and 6.0 degrees C. PSRE were not significantly different in summer (15.69+/-4.41%) or winter (20.59+/-4.45%), but values were considerably lower than those previously reported in temperate and tropical species. A meta-analysis of published ectotherm PSRE suggested there was a positive relationship with temperature (y=449.9-114.9x, r(2)=28.8%, P<0.05). In turn, this suggests that temperature may be an important factor in determining ectotherm growth efficiency via an influence on PSRE. Maximal fractional and absolute protein synthesis rates occurred at approximately 1 degrees C in N. concinna, the approximate summer water temperature at the study site, and protein synthesis rates decreased above this temperature. In the absence of adaptation, predicted increases in Antarctic water temperatures would result in reduced, rather than increased, rates of protein synthesis and, in turn, possibly growth.Journal of Experimental Biology 09/2007; 210(Pt 15):2691-9. · 3.00 Impact Factor -
Article: Energetic cost of synthesizing proteins in Antarctic limpet, Nacella concinna (Strebel, 1908), is not temperature dependent.
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ABSTRACT: The energetic cost of protein synthesis is thought to account for a significant proportion of total metabolism. However, attempts to estimate the energetic cost of synthesizing proteins have resulted in surprisingly variable results, particularly for the small number of polar organisms studied, where cost estimates vary by two orders of magnitude. Much of this variability is probably the result of differing methodologies and experimental designs. Here we have used two different, carefully validated methods to measure the costs of protein synthesis in Antarctic limpets. One method, which utilized a specific protein synthesis inhibitor, was used to measure the cost of protein synthesis at two temperatures to test the hypothesis that the cost of protein synthesis varies with temperature. The cost of protein synthesis measured using the inhibitor cycloheximide was 13.95 +/- 0.77 micromol O2/mg protein, while correlation of absolute protein synthesis with oxygen consumption suggested the cost of protein synthesis was 19.58 micromol O2/mg protein. Water temperature did not alter the cost of protein synthesis in Nacella concinna (Student's t-test, P = 0.849, t = 0.19, df = 12). In a meta-analysis of literature values for the cost of protein synthesis there was no significant effect of temperature, but there was a significant relationship between the concentration of cycloheximide used to inhibit protein synthesis and the measured cost.AJP Regulatory Integrative and Comparative Physiology 07/2007; 292(6):R2266-74. · 3.34 Impact Factor -
Article: Protein metabolism in marine animals: the underlying mechanism of growth.
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ABSTRACT: Growth is a fundamental process within all marine organisms. In soft tissues, growth is primarily achieved by the synthesis and retention of proteins as protein growth. The protein pool (all the protein within the organism) is highly dynamic, with proteins constantly entering the pool via protein synthesis or being removed from the pool via protein degradation. Any net change in the size of the protein pool, positive or negative, is termed protein growth. The three inter-related processes of protein synthesis, degradation and growth are together termed protein metabolism. Measurement of protein metabolism is vital in helping us understand how biotic and abiotic factors affect growth and growth efficiency in marine animals. Recently, the developing fields of transcriptomics and proteomics have started to offer us a means of greatly increasing our knowledge of the underlying molecular control of protein metabolism. Transcriptomics may also allow us to detect subtle changes in gene expression associated with protein synthesis and degradation, which cannot be detected using classical methods. A large literature exists on protein metabolism in animals; however, this chapter concentrates on what we know of marine ectotherms; data from non-marine ectotherms and endotherms are only discussed when the data are of particular relevance. We first consider the techniques available to measure protein metabolism, their problems and what validation is required. Protein metabolism in marine organisms is highly sensitive to a wide variety of factors, including temperature, pollution, seasonality, nutrition, developmental stage, genetics, sexual maturation and moulting. We examine how these abiotic and biotic factors affect protein metabolism at the level of whole-animal (adult and larval), tissue and cellular protein metabolism. Available gene expression data, which help us understand the underlying control of protein metabolism, are also discussed. As protein metabolism appears to comprise a significant proportion of overall metabolic costs in marine organisms, accurate estimates of the energetic cost per unit of synthesised protein are important. Measured costs of protein metabolism are reviewed, and the very high variability in reported costs highlighted. Two major determinants of protein synthesis rates are the tissue concentration of RNA, often expressed as the RNA to protein ratio, and the RNA activity (k(RNA)). The effects of temperature, nutrition and developmental stage on RNA concentration and activity are considered. This chapter highlights our complete lack of knowledge of protein metabolism in many groups of marine organisms, and the fact we currently have only limited data for animals held under a narrow range of experimental conditions. The potential assistance that genomic methods may provide in increasing our understanding of protein metabolism is described.Advances in Marine Biology 02/2007; 52:267-362. · 2.04 Impact Factor -
Article: Antarctic Genomics
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ABSTRACT: With the development of genomic science and its battery of technologies, polar biology stands on the threshold of a revolution, one that will enable the investigation of important questions of unprecedented scope and with extraordinary depth and precision. The exotic organisms of polar ecosystems are ideal candidates for genomic analysis. Through such analyses, it will be possible to learn not only the novel features that enable polar organisms to survive, and indeed thrive, in their extreme environments, but also fundamental biological principles that are common to most, if not all, organisms. This article aims to review recent developments in Antarctic genomics and to demonstrate the global context of such studies.Comparative and Functional Genomics 01/2006; · 1.28 Impact Factor -
Article: Links between the structure of an Antarctic shallow-water community and ice-scour frequency.
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ABSTRACT: Ice is a major structuring force in marine and freshwater environments at high latitudes. Although recovery from scouring has been quantified in time, the frequency of scouring in the Antarctic has not. We placed grids of markers at 9-17 m depth at two sites, to study ice-scouring over 2 years at Adelaide island (Antarctic Peninsula). We quantified the time scale of scour frequencies, and linked this to community mortality, age and diversity. Markers were hit from zero to at least three times in 2 years. At the least disturbed site (South Cove) 24% of markers were destroyed per year, whereas in North Cove 60% of markers were destroyed. There were significant differences in scouring frequency between our two sites: a given area in North Cove was on average hit twice as often as one in South Cove. Compared with near shore environments elsewhere, faunas of both sites were characteristic of high disturbance regimes, exhibiting low percent cover, diversity, ages and a high proportion of pioneers. Aspects of the encrusting communities studied reflected the differences between site disturbance regimes. North Cove was scoured twice as often, and bryozoan communities there had half the number of species, two-thirds the space occupation and twice the mortality level of those in South Cove. Maximum age in North Cove bryozoans was also half that in South Cove. Although there are natural disturbance events that rival ice-scouring in either frequency or catastrophic power at lower latitudes, none do both nor across such a wide depth range. We suggest that ice scour effects on polar benthos are even more significant than the same magnitude of disturbance at lower latitudes as recovery rates of high latitude communities are very slow. Climate warming seems likely to increase iceloading of near shore polar waters, so that some of the world's most intensely disturbed faunas may soon suffer even more disturbance.Oecologia 10/2004; 141(1):121-9. · 3.41 Impact Factor -
Article: Antarctic genomics.
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ABSTRACT: With the development of genomic science and its battery of technologies, polar biology stands on the threshold of a revolution, one that will enable the investigation of important questions of unprecedented scope and with extraordinary depth and precision. The exotic organisms of polar ecosystems are ideal candidates for genomic analysis. Through such analyses, it will be possible to learn not only the novel features that enable polar organisms to survive, and indeed thrive, in their extreme environments, but also fundamental biological principles that are common to most, if not all, organisms. This article aims to review recent developments in Antarctic genomics and to demonstrate the global context of such studies.Comparative and Functional Genomics 01/2004; 5(3):230-8. · 1.28 Impact Factor -
Article: Low-temperature protein metabolism: seasonal changes in protein synthesis and RNA dynamics in the Antarctic limpet Nacella concinna Strebel 1908.
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ABSTRACT: Protein synthesis is a fundamental and energetically expensive physiological process in all living organisms. Very few studies have examined the specific challenges of manufacturing proteins at low ambient temperatures. At high southern latitudes, water temperatures are continually below or near freezing and are highly stable, while food availability is very seasonal. To examine the effects of low temperature and a highly seasonal food supply on protein metabolism, we have measured wholebody protein synthesis, RNA concentrations, RNA:protein ratios and RNA translational efficiencies in the Antarctic limpet Nacella concinna at four times of the year. From summer to winter, protein synthesis rates decreased by 52%, RNA concentrations decreased by 55% and RNA:protein ratios decreased by 68%, while RNA translational efficiencies were low and very variable. Protein synthesis rates in N. concinna approached those measured in temperate mussels, while RNA:protein ratios were considerably higher than in temperate species. Interspecific comparisons show that species living at low temperatures have elevated RNA:protein ratios, which are probably needed to counteract a thermally induced reduction in RNA translational efficiency. Calculations using theoretical energetic costs of protein synthesis suggest that Antarctic species may allocate a larger proportion of their metabolic budget to protein synthesis than do temperate or tropical species.Journal of Experimental Biology 11/2002; 205(Pt 19):3077-86. · 3.00 Impact Factor -
Article: Protein synthesis, RNA concentrations, nitrogen excretion, and metabolism vary seasonally in the Antarctic holothurian Heterocucumis steineni (Ludwig 1898).
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ABSTRACT: Seasonal changes in protein and nitrogen metabolism have not previously been reported in any Antarctic suspension-feeding species that ceases feeding for extended periods in winter. To provide comparison with data reported on Nacella concinna, a species that continues to feed in winter, we have measured feeding activity; oxygen consumption; ammonia, urea, and fluorescamine-positive substance (FPS) excretion; O : N ratios; body wall protein synthesis; RNA to protein ratios; and RNA activity at three times during the year in an Antarctic suspension-feeding holothurian. Feeding activity ceased for 4 mo during winter, and oxygen consumption rates decreased from 8.79+/-0.43 micro mol h(-1) to 4.48+/-0.34 micro mol h(-1). Ammonia excretion also decreased during winter from 2,600+/-177 nmol N h(-1) to 974+/-70 nmol N h(-1), but urea excretion rates increased from 178+/-36 nmol N h(-1) to 281+/-110 nmol N h(-1), while FPS excretion rates remained unchanged throughout the year with a seasonal mean of 88+/-13 nmol N h(-1). Oxygen to nitrogen ratios ranged between 6 and 10, suggesting that proteins were used as the primary metabolic substrate. Body wall protein synthesis rates decreased from 0.35%+/-0.03% d(-1) in summer to 0.23% d(-1) in winter, while RNA to protein ratios decreased from 33.10+/-1.0 microg RNA mg(-1) protein in summer to 27.88+/-1.3 microg RNA mg(-1) protein in winter, and RNA activity was very low, ranging between 0.11+/-0.01 mg protein mg(-1) RNA d(-1) in summer and 0.06+/-0.01 mg protein mg(-1) RNA d(-1) in winter. Heterocucumis steineni shows a larger seasonal decrease in oxygen consumption and ammonia excretion between February (summer) and July (winter) than N. concinna, while the proportional decrease in protein synthesis rates is similar in both species.Physiological and Biochemical Zoology 77(4):556-69. · 2.20 Impact Factor -
Article: Scavenging in Antarctica: Intense variation between sites and seasons in shallow benthic necrophagy
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ABSTRACT: The response of scavengers to a feeding cue at Adelaide Island, West Antarctic Peninsula was investigated using a baited video camera system. Fourteen experimental deployments, each lasting 72 h were conducted at two contrasting sites during the winter and summer of 2005. The rate of bait consumption varied between sites but not between seasons, and was low in comparison with studies at lower latitudes and greater depths. At the Hangar Cove site, the nemertean Parborlasia corrugatus was out-competed at the bait and displaced by the lysianassid amphipod Cheirmedon femoratus during winter. However, C. femoratus did not feed on the bait during summer, allowing P. corrugatus to monopolise the feeding opportunity. At the South Cove site the asteroid Odontaster validus dominated the bait in both seasons but sporadic feeding by the nototheniid fish Notothenia coriiceps considerably affected consumption rates during two of the six deployments. Scavengers were attracted to the bait in very high numbers and opportunistic necrophagy seems to be a successful strategy in an environment that is intensely disturbed by ice.Journal of Experimental Marine Biology and Ecology. -
Article: Life in the fast lane: The free-ranging activity, heart rate and metabolism of an Antarctic fish tracked in temperate waters
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ABSTRACT: The fish species Notothenia angustata inhabits temperate waters (10 °C), yet retains physiological traits that show it once existed at sub-zero temperatures. We determined the free-ranging activity, heart rate and metabolism of N. angustata and compared it with Notothenia coriiceps, an ecologically and morphologically congeneric cousin that still inhabits sub-zero waters. Firstly, the association between heart rate (fH) and oxygen consumption (MO2) was first determined in the laboratory. The fish were then released into their respective environments and fH recorded by a miniature archival electronic tag, from which the metabolic rate of the free-ranging fish was extrapolated. Free-ranging activity of wild fish was monitored throughout the study using implanted acoustic tags and a static hydrophone array. Results showed that the difference in standard metabolic rate (SMR) between N. angustata and N. coriiceps fitted the Arrhenius model for inter-species thermal sensitivity in fish (Q10 = 1.76). However, the inter-species disparity in total metabolic rate (TMR) was far greater. This was attributable to N. angustata swimming at higher speeds and covering a 5-fold greater area over 24 h compared with N. coriiceps. As a result, activity (and associated feeding) comprised a far larger portion of TMR in N. angustata (27.9%) than for N. coriiceps (5.7%). We conclude that the increased time spent swimming by N. angustata was presumably to forage for food to acquire sufficient energy to fuel its elevated SMR. This resulted in a much greater inter-species difference in TMR than may be predicted by the disparity in environmental temperature.Journal of Experimental Marine Biology and Ecology. -
Article: Genomics: applications to Antarctic ecosystems
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ABSTRACT: Biological research in Antarctica has made considerable progress in science over recent decades. As little as 50 years ago, there was scant knowledge even of the species inhabiting the region. Since then, understanding has developed rapidly, across diverse disciplines including physiology, biochemistry, ecology and biogeography. Some dramatic global-scale discoveries and advances have been made, including the characterisation of antifreeze proteins from notothenioid fish and the finding that some fish lack a heat shock response, the identification of microbial communities living within the surface layers of rocks and description of the simplest faunal communities known, the identification that possibly the fastest environmental and ecological change on earth is occurring in Antarctic lakes, and that the biodiversity of the Southern Ocean is much greater than previously thought. Findings such as these have made biology in cold extreme environments one of the most stimulating areas for research in recent decades. Now, the advent and widespread applicability of the novel genomic technologies promise to move us into a period of equally, or possibly even more, rapid advance. At present, genomic information on Antarctic species is limited mainly to a number of fish species and microbes. However, an increasing number of Antarctic genomics projects are being funded and will significantly increase the amount of molecular information available on a much wider range of species in the near future. Hence it is timely to review progress so far in the use of genomic methods in Antarctic research and identify exciting prospects for dramatic future advances. -
Article: Protein Metabolism in Marine Animals: The Underlying Mechanism of Growth
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ABSTRACT: Growth is a fundamental process within all marine organisms. In soft tissues, growth is primarily achieved by the synthesis and retention of proteins as protein growth. The protein pool (all the protein within the organism) is highly dynamic, with proteins constantly entering the pool via protein synthesis or being removed from the pool via protein degradation. Any net change in the size of the protein pool, positive or negative, is termed protein growth. The three inter‐related processes of protein synthesis, degradation and growth are together termed protein metabolism. Measurement of protein metabolism is vital in helping us understand how biotic and abiotic factors affect growth and growth efficiency in marine animals. Recently, the developing fields of transcriptomics and proteomics have started to offer us a means of greatly increasing our knowledge of the underlying molecular control of protein metabolism. Transcriptomics may also allow us to detect subtle changes in gene expression associated with protein synthesis and degradation, which cannot be detected using classical methods. A large literature exists on protein metabolism in animals; however, this chapter concentrates on what we know of marine ectotherms; data from non‐marine ectotherms and endotherms are only discussed when the data are of particular relevance. We first consider the techniques available to measure protein metabolism, their problems and what validation is required. Protein metabolism in marine organisms is highly sensitive to a wide variety of factors, including temperature, pollution, seasonality, nutrition, developmental stage, genetics, sexual maturation and moulting. We examine how these abiotic and biotic factors affect protein metabolism at the level of whole‐animal (adult and larval), tissue and cellular protein metabolism. Available gene expression data, which help us understand the underlying control of protein metabolism, are also discussed. As protein metabolism appears to comprise a significant proportion of overall metabolic costs in marine organisms, accurate estimates of the energetic cost per unit of synthesised protein are important. Measured costs of protein metabolism are reviewed, and the very high variability in reported costs highlighted. Two major determinants of protein synthesis rates are the tissue concentration of RNA, often expressed as the RNA to protein ratio, and the RNA activity (kRNA). The effects of temperature, nutrition and developmental stage on RNA concentration and activity are considered. This chapter highlights our complete lack of knowledge of protein metabolism in many groups of marine organisms, and the fact we currently have only limited data for animals held under a narrow range of experimental conditions. The potential assistance that genomic methods may provide in increasing our understanding of protein metabolism is described.Advances in Marine Biology.
Top co-authors
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Institutions
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2004–2008
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British Antarctic Survey
Cambridge, ENG, United Kingdom
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2007
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British Antarctic Survey
Cambridge, ENG, United Kingdom
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