Low activity and seasonal change in population size structure of grenadiers in the oligotrophic abyssal central North Pacific Ocean

Analysis of video recordings of swimming in abyssal grenadiers Coryphaenoides spp. revealed site differences in tail-beat frequencies. At the highly oligotrophic deep central North Pacific (CNP; 5800 m depth) station fishes had significantly lower tail-beat frequencies (0·73 ± 0·02 Hz, mean ±  s . e .) than fishes of similar size at the shallower 'Station F' (Sta. F; 4400 m depth) beneath the more productive waters of the California Current Upwelling (1·06 ± 0·04 Hz). These behavioural differences may be evidence for the proposed physiological adaptations of Coryphaenoides armatus and Coryphaenoides yaquinae , to different depths and food supply levels. At CNP, smaller fishes (38·9 cm mean L _T) were present in autumn than in summer (59·4 cm L _T) suggesting large-scale migrations across the abyssal ocean floor despite the observed slow swimming speeds.     

Abundance of Petrolisthes armatus (Crustacea: Porcellanidae) on a tropical estuarine intertidal rocky beach, Gulf of Nicoya estuary, Costa Rica

Population of the porcellanid crab Petrolisthes armatus was studied on a rocky intertidal beach located at the Punta Morales peninsula in the mid upper Gulf of Nicoya estuary, Pacific coast of Costa Rica, from December 1997 to November 1998 (14 dates). Horizontal plankton tows (280 micron mesh net) were also made to verify the presence of P. armatus larvae. Crabs were collected every 3 m along three 18 m long transects, at two sites on the beach, by placing a bottomless bucket fringed with canvas to prevent the organisms from escaping under the rim. A total of 15,382 P. armatus were collected. Only 146 (0.95%) crabs had a carapace length longer than 10 mm, and 8995 (58.5%) were in the size range of 2 to 4.5 mm. The remaining crabs 6241 (40.5%) were in the size range of 4.6 to 10 mm. Male and female P. armatus were represented by 2777 and 3518 individuals respectively, with a sex ratio of 1:1.26. Ovigerous females were found at all dates and included 2937 individuals (83% of females). Plankton tows yielded only 73 larvae of P. armatus (Zoea 1), with a density of 1.2 larvae/m3. No statistically significant seasonal trends in the population of this species were detected. P. armatus appears to reproduce continuously the year around in Punta Morales, and some peaks of abundance were present during the dry and rainy seasons. These trends are similar to trends reported for other crustacean species in the Gulf of Nicoya.     

Influence of life history and seasonal hydrology on lipid storage in three neotropical fish species

The seasonal dynamics of energy (lipid) storage in three neotropical fish species with differing life histories were evaluated. Lipid content was substantially greater in the liver than in dorsal musculature of all three species. Two piscivores ( Cichla temensis and Serrasalmus manueli ) showed large, statistically significant seasonal fluctuations in liver lipid content. Liver lipid content increased during high water, through the falling water, and into the early dry season for both piscivores. Seasonal variation in dorsal muscle lipid content was large and statistically significant for C. temensis , but was small and non‐significant for S. manueli . Cichla temensis appeared to 'finance' costs associated with reproduction by accumulating lipids during the falling‐water period when migratory prey allowed the species to subsidize their energetic dynamics. Semaprochilodus kneri , a migratory algivore and detritivore, showed no significant seasonal variation in dorsal muscle lipid content and minimally significant seasonal variation in liver lipid content. Statistically significant effects of lipid content on δ¹³C was observed when tissue lipid content varied by >12%, while biological interpretation of food web statistics based on δ¹³C values appears robust to minor variations in lipid content. Nonetheless, when lipid content varied by larger amounts ( e.g . >35% for C. temensis and S. manueli liver tissue) lipids appeared to have a large potential effect on δ¹³C and food web statistics calculated from such measurements may have been biased. Surprisingly, even large variation in tissue lipid content did not affect δ¹⁵N.     

The effects of hydrostatic pressure on pertussis toxin-catalyzed ribosylation of G proteins from deep-living macrourid fishes

To test the effects of hydrostatic pressure on the coupling of receptors to guanyl nucleotide binding reglatory proteins (G proteins) in transmembrane signaling, pertussis toxin (PTX)-catalyzed [32P]ADP-ribosylation was used to probe the guanyl nucleotide-binding proteins Gi and G(o) in brain membranes from four marine teleosts. These macrourids, Coryphaenoides pectoralis, Coryphaenoides cinereus, Coryphaenoides filifer and Coryphaenoides armatus, span depths from 200 to 5400 m. Pertussis toxin specifically labelled proteins of 39-41 kDa. The PTX-catalyzed [32P]ADP-ribosylation reaction was linear for 7 h. Added guanyl nucleotides (guanosine 5'-diphosphate (GDP) and guanosine 5'-O-(3-thiotriphosphate)(GTP[S])) at concentrations up to 1000 microM did not affect ribosylation at atmospheric pressure. Under basal conditions the Gi/G(o) protein population appears to be uncoupled from receptors and bound with GDP. Pressures up to 476 atm were tested in the absence and presence of added guanyl nucleotides, 100 microM GDP and 100 microM GTP[S]. [32P]ADP-ribosylation in brain membranes from the deeper-occurring C. cinereus, C. filifer and C. armatus was not inhibited by increased pressure in the presence of 100 microM GDP. Increasing pressure decreased ribosylation in brain membranes of C. pectoralis. In the presence of 100 microM GTP[S], increased pressure inhibited ribosylation in all species. Pressure appears to enhance the efficacy of GTP[S] in dissociating the heterotrimeric holoprotein.     

Structure-based analysis of high pressure adaptation of alpha-actin

Deep-sea fishes occur to depths of several thousand meters, and at these abyssal depths encounter pressures that shallower living fishes cannot tolerate. Tolerance of abyssal pressures by deep-sea fish is likely to depend in part on adaptive modifications of proteins. However, the types of structural modifications to proteins that allow function at high pressure have not been discovered. To elucidate the mechanisms of protein adaptation to high pressure, we cloned the alpha-skeletal actin cDNAs from two abyssal Coryphaenoides species, C. armatus and C. yaquinae, and identified three amino acid substitutions, V54A or L67P, Q137K, and A155S, that distinguish these abyssal actins from orthologs of alpha-actin from non-abyssal Coryphaenoides. These substitutions, Q137K and A155S, prevent the dissociation reactions of ATP and Ca2+ from being influenced by high pressure. In particular, the lysine residue at position 137 results in a much smaller apparent volume change in the Ca2+ dissociation reaction. The V54A or L67P substitution reduces the volume change associated with actin polymerization and has a role in maintaining the DNase I activity of actin at high pressure. Together, these results indicate that a few amino acid substitutions in key functional positions can adaptively alter the pressure sensitivity of a protein.     

Sequential changes in cell morphology of an obligately barophilic deep-sea bacterium during its growth at high pressures

Abstract An obligately barophilic bacterium isolated from intestinal content of a deep-sea fish ( Coryphaenoides yaquinae ), which was retrieved from a depth of 6100 m in the Northwest Pacific Ocean, swelled in the early-exponential phase, elongated in the midexponential phase, thinned in the late-exponential phase, and shortened in the stationary phase when incubated both at 82.7 MPa and at 41.4 MPa around the optimum growth pressure. The same changes were observed at any pressures where the strain could grow. We propose to call such morphological changes the SETS (swell-elongate-thin-shorten) phenomenon. These results suggest the possibility that the SETS phenomenon might occur in the growth of the strain at high-pressure deep-sea environments.     

Behaviour of the abyssal grenadier, Coryphaenoides yaquinae, monitored using ingestible acoustic transmitters in the Pacific Ocean

Scavenging grenadier fishes, Coryphaenoides yaquinae , were tracked with ingestible acoustic tags at 5800 m depth in the central North Pacific. A free-fall vehicle comprising a video camera and recording system together with a hydrophone, ultrasonic acoustic receiver and recorder was deployed on the sea bed. Special acoustic transmitters (75 kHz) were wrapped in bait and attached below and in view of the camera. Grenadiers were observed to ingest the baited transmitters and move away to ranges of over 100 m within 5h, some returning several times to within range of the receiving system. Voluntary ingestion of transmitters by this grenadier demonstrates that an inacessible population can be studied and provides a basis for development of automated tracking systems for long-term monitoring of individual deep-sea fish.     

The Lepocreadiidae (Digenea) of fishes from the north-east Atlantic: a review of the genusLepidapedon Stafford, 1904

The genusLepidapedon is subdivided into several species groups and subgroups of species based on the vitelline distribution and the length of the excretory vesicle. The species in each of the subgroups are listed and keys to the species in most subgroups are given. The following north-eastern Atlantic species are described or redescribed:Lepidapedon rachion fromMelanogrammus aeglefinus, Gadus morhua, Aspitrigla cuculus, Merlangius merlangus andPollachius pollachius; L. cambrensis fromEnchelyopus cimbrius; L. sommervillae n. sp. fromTrachyrincus scabrus, T. murrayi andCoryphaenoides guentheri; L. elongatum fromGadus morhua; L. gaevskayae fromCoryphaenoides (Nematonurus) armatus; L. discoveryi n. sp. fromCoryphaenoides (Nematonurus) armatus; L. arlenae n. sp. fromTrachyrincus scabrus andT. murrayi; L. mariannae n. sp. fromGaidropsarus argentatus; Lepidapedon spp. innom (Elongatum-group) fromCoryphaenoides guentheri andCoryphaenoides (Chalinura) leptolepis; L. desclersae n. sp. fromLepidion eques; L. beveridgei fromCoryphaenoides (Nematonurus) armatus andC. (Chalinura) mediterraneus; andL. zubchenkoi fromCoryphaenoides (Chalinura) leptolepis andC. (C.) profundicolus. The phylogeny, host-specificity and zoogeography of the genus are briefly discussed.     

Correlation of trimethylamine oxide and habitat depth within and among species of teleost fish: an analysis of causation

Most shallow-water teleosts have moderate levels of trimethylamine N-oxide (TMAO; approximately 50 mmol/kg wet mass), a common osmolyte in many other marine animals. Recently, muscle TMAO contents were found to increase linearly with depth in six families. In one hypothesis, this may be an adaptation to counteract the deleterious effects of pressure on protein function, which TMAO does in vitro. In another hypothesis, TMAO may be accumulated as a by-product of acylglycerol (AG) production, increasing with depth because of elevated lipid metabolisms known to occur in some deep-sea animals. Here we analyze muscle TMAO contents and total body AG (mainly triacyglycerol [TAG]) levels in 15 species of teleosts from a greater variety of depths than sampled previously, including eight individual species caught at two or more depths. Including data of previous studies (total of 17 species, nine families), there is an apparent sigmoidal increase in TMAO contents between 0- and 1.4-km depths, from about 40 to 150 mmol/kg. From 1.4 to 4.8 km, the increase appears to be linear (r2=0.91), rising to 261 mmol/kg at 4.8 km. The trend also occurred within species: in most cases in which a species was caught at two or more depths, TMAO was higher in the deeper-caught specimens (e.g., for Coryphaenoides armatus, TMAO was 173, 229, and 261 mmol/kg at 1.8, 4.1, and 4.8 km, respectively). TMAO contents not only were consistent within species at a given depth but also did not vary with season or over a wide range of body masses or TAG contents. Thus, no clear link between TMAO and lipid was found. However, TMAO contents might correlate with the rate (rather than content) of TAG production, which could not be quantified. Overall, the data strongly support the hypothesis that TMAO is adaptively regulated with depth in deep-sea teleosts. Whether lipid metabolism is the source of that TMAO is a question that remains to be tested fully.     

Estimation of abundance of abyssal demersal fishes; a comparison of data from trawls and baited cameras

The abundance of the macrourid Coryphaenoides (Nematonurus) armatus was investigated using a single warp trawl and baited camera at soundings from 2500 to 5000 m in the north-east Atlantic Ocean. There was no significant relationship between abundance ( n km⁻²) as determined from swept area of the trawl and numbers of fish photographed at standard baits. However, timing of the first arrival ( t _arr s) of the first fish at bait correlated well with the trawl data through the relationship: It is concluded that by measurement of arrival times, the baited camera provides a cost-effective complement to trawl sampling for estimating abundance of deep-water fish including Synaphobranchus kaupi, Anlimora rostratu and C. (N). armatus. However, some abundant species such as the roundnose grenadier Coryphaenoides rupestris were not attracted to baited long-lines or baited cameras and therefore could be sampled only by trawl.     

Myxozoa of deep-sea fishes in the northwestern Atlantic

The gall bladder of 5 species of deep-water fishes (Coryphaenoides armatus, Coryphaenoides rupestris, Macrourus berglax, Antimora rostrata, and Synaphobranchus kaupi) from the New York Bight and Carson Canyon areas in the northwest Atlantic were examined for myxozoan parasites. Myxidium coryphaenoidium was found in 4 fish species, whereas Auerbachia pulchra and Ceratomyxa sp. were each observed in 1 fish species. Prevalence of myxozoan infections was greater in fishes taken off the New York Bight than from the Carson Canyon.     

Pressure effects on actin self-assembly: interspecific differences in the equilibrium and kinetics of the G to F transformation

Purified skeletal muscle actins from species whose ambient pressures range from 1 to greater than 500 atm were examined for the sensitivity to hydrostatic pressure of the globular (G) to filamentous (F) self-assembly reaction. Both the equilibrium position and the kinetics of self-assembly were affected by pressure. Increased pressure shifted the self-assembly equilibrium toward the monomer (G) state and reduced the rate of F-actin assembly. For most of the actins studied, the perturbation by pressure of F-actin formation decreased with increasing measurement of pressure, indicating that F-actin has a higher compressibility than G-actin. The increase in system volume and compressibility concomitant with the assembly of F-actin can be interpreted as reflections of the major role played by hydrophobic effects in stabilizing F-actin and of the existence of "hard" binding sites, in the terminology of Torgerson et al. [Torgerson, P. M., Drickamer, H. G., & Weber, G. (1979) Biochemistry 18, 3079-3083], in the actin subunits. For actin from the deepest occurring species studied, the teleost fish Coryphaenoides armatus, which occurs to depths of approximately 5000 m (equivalent to 501 atm of pressure), there was no difference in compressibility between G-actin and F-actin; that is, the effect of increasing pressure on self-assembly was linear over the entire pressure range examined, 600 atm. The self-assembly reaction of the actin from C. armatus also differed from that of the other actins examined in that the G to F equilibrium was relatively insensitive to increased pressure; i.e., the volume change (delta V) of assembly was small.(ABSTRACT TRUNCATED AT 250 WORDS)     

Composition of lipid foams from swim bladders of two deep ocean fish species

Lipid-containing deposits within the swim bladders of Coryphaenoides acrolepis and Antimora rostrata were investigated. Lipid analysis of this material, which was quite uniform from the two species, yielded the following data: neutral lipids, 36.0-41.7%; phospholipids, 53.6-56.7%; and glycolipids, 4.3-8.9%. Cholesterol (mainly in the free form) constituted 60.4%-77.8% of the neutral lipids. Sphingomyelin and phosphatidylcholine were the principal phospholipids, with sphingomyelin highest in the material from C. acrolepis and phosphatidylcholine predominant in that from A. rostrata. The overall pattern of lipids shows a resemblance to that of plasma membrane, particularly in the relatively high levels of free cholesterol, sphingomyelin, and phosphatidylserine. The lipid-to-protein ratio of the material is approximately 1.5-2 to 1. The lipids of the fine inner lining (tunica interna) of the swim bladder from a shallow water fish, the kelp bass (Paralabrax clathratus), had essentially the same composition as the much more abundant swim bladder material from the deep ocean fishes.     

Diurnal and Infradian Rhythms in Lipid Parameters of Indian Catfish,Heteropneustes fossilis

Twentyfour-hour variation in (14 C) acetate incorporation in the liver lipid, and lipid concentrations in the liver and muscle tissues were studied during different phases of the annual reproductive cycle in the female freshwater catfish, H. fossilis. A 24-h rhythm in hepatic lipogenic activity was validated. Lipid concentration in liver and muscle also varied in a rhythmic fashion (t = 24 h). The mesor and amplitude of these rhythms appeared to be modulated by the phase of the annual gonadal cycle of H. fossilis. All three lipid parameters, in addition, exhibited low frequency rhythms with a t = 6 months or 3 months. The results indicate that the time of the day and month of the year for sampling in any experiment involving examination of lipid metabolism are of critical importance.     

Trimethylamine oxide, betaine and other osmolytes in deep-sea animals: depth trends and effects on enzymes under hydrostatic pressure.

Most shallow teleosts have low organic osmolyte contents, e.g. 70 mmol/kg or less of trimethylamine oxide (TMAO). Our previous work showed that TMAO contents increase with depth in muscles of several Pacific families of teleost fishes, to about 180 mmol/kg wet wt at 2.9 km depth in grenadiers. We now report that abyssal grenadiers (Coryphaenoides armatus, Macrouridae) from the Atlantic at 4.8 km depth contain 261 mmol/kg wet wt in muscle tissue. This precisely fits a linear trend extrapolated from the earlier data. We also found that anemones show a trend of increasing contents of methylamines (TMAO, betaine) and scyllo-inositol with increasing depth. Previously we found that TMAO counteracts the inhibitory effects of hydrostatic pressure on a variety of proteins. We now report that TMAO and, to a lesser extent, betaine, are generally better stabilizers than other common osmolytes (myo-inositol, taurine and glycine), in terms of counteracting the effects of pressure on NADH Km of grenadier lactate dehydrogenase and ADP Km of anemone and rabbit pyruvate kinase.     

Seasonal variations of lipid fatty acids of boreal freshwater fish species

1. The fatty acid levels of muscle and liver lipids of perch, vendace and rainbow trout (Salmo gairdneri) cultivated in the same area (for comparison) were monitored. 2. The total lipid content in the muscle of perch (Perca fluviatilis) and vendace (Coregonus albula) was less than 50% of that in rainbow trout and a seasonal variation was clear only in vendace. 3. The relative amounts of polyunsaturated fatty acids as well as omega-3 acids were higher in vendace and perch than in cultivated rainbow trouts. Arachidonic acid content was much higher in vendace and perch than in rainbow trout. The content of monoenes was considerably higher in rainbow trout than in free freshwater fish. 4. The seasonal variations in the degree of unsaturation were small in fish muscle. 5. In the muscle of rainbow trout the relative amount of polyunsaturated fatty acids diminished with the increase of total lipids.     

Function of the liver and hepatic lipids of the lesser sand shark, Rhinobatos annulatus (Müller & Henle)

Seasonal variation recorded in the hepatosomatic index for sand sharks, Rhinobatos annulatus, was primarily due to accumulation of hepatic lipids. The contribution of liver lipids to the formation of egg yolk was estimated and found to be secondary to lipid reserves for metabolic functions. Maximum liver lipid content in mature sand sharks coincided with peak breeding activities. Hepatic lipids and their derivatives are an important fuel for muscle and thus needed for migration which occurred soon after parturition and mating. Liver colour was in synchrony with the variation in the total liver lipid content in both sexes of sand sharks.     

Infusion of a Lipid Emulsion Modulates AMPK and Related Proteins in Rat Liver,Muscle, and Adipose Tissues

The primary objective of this study was to investigate the impact of lipid oversupply on the AMPK pathway in skeletal muscle, liver, and adipose tissue. Male Wistar rats were infused with lipid emulsion (LE) or phosphate‐buffered saline for 5 h/day for 6 days. Muscles exposed to LE for 6 days exhibited increased AMPK and acetyl‐CoA carboxylase (ACC) phosphorylation, along with a greater association between AMPK and Ca²⁺/calmodulin‐dependent protein kinase kinase (CaMKK). No differences in muscle protein phosphatase 2C (PP2C) activity, LKB1 phosphorylation or AMPK and LKB1 association were observed. Muscle ACCβ, and adiponectin receptor 1 (AdipoR1) mRNA levels and PPARγ‐co‐activator 1α (PGC1α) protein levels were also increased in LE‐treated rats. In contrast, AMPK and ACC phosphorylation decreased and PP2C activity increased in rat livers exposed to LE. Hepatic mRNA levels of ACCα, PPARα, AdipoR1, AdipoR2, and sterol regulatory element–binding protein‐1c (SREBP1c) were also reduced after LE infusion. In adipose tissue, there was no significant alteration in AMPK or ACC phosphorylation. These results demonstrate that following lipid oversupply the AMPK pathway was enhanced in rat skeletal muscle while diminished in the liver and was unchanged in adipose tissue. CaMKK in skeletal muscle and PP2C in the liver, at least in part, appear to mediate these alterations. Alterations in AMPK pathway in the liver induced metabolic defects associated with lipid oversupply.     

Effects of bovine growth hormone on plasma FFA concentrations and liver, muscle and carcass lipid content in rainbow trout, Salmo gairdneri Richardson

Bovine growth hormone (GH) given daily to rainbow trout, Sulmo gairdneri for 4 or 7 days at either 10.00 or 14.00 hours, significantly increased plasma free fatty acid (FFA) levels but had not effect on plasma cholesterol levels. Liver lipid content of the GH-injected trout after seven injections was significantly lower than comparable controls in groups injected at both 10.00 and 14.00 hours. There were no apparent effects of GH on carcass or muscle lipid content although in fish injected and sampled at 14.00 hours there was a significant correlation between the number of injections and carcass lipid content.
Changes in hepatosomatic index (HSI), liver, muscle and carcass lipid content, plasma FFA and cholesterol concentrations and somatotrop activity during food-deprivation for up to 60 days are described. Despite significant decreases in liver and muscle lipid content and increases in plasma FFA levels in food-deprived fish, there was no concomitant change in apparent somatotrop activity.
The data are interpreted to indicate that although exogenous GH, in the doses used here, appears to stimulate mobilization of lipid reserves, particularly from the liver, there is no evidence that enforced changes in lipid reserves elicits a response of the endogenous somatotrop cells.     

Seasonal variations in the intermediate metabolism of Parastacus varicosus (Crustacea, Decapoda, Parastacidae)

The aim of this study was to analyze the seasonal variations in the metabolism of Parastacus varicosus and examine the possible relationships to its reproduction. Animals were sampled (9 h to 10 h) in each month in the Gravataí River, RS, Brazil. Haemolymph samples were collected from each crayfish in the field for determination of glucose, total proteins, total lipids, and total cholesterol. Hepatopancreas, abdominal muscle, and gonads were removed for determination of glycogen, total proteins, total lipids, and total cholesterol. ANOVA revealed significant seasonal differences in the biochemical composition of all tissues studied; when the sexes were compared these parameters did not show any significant difference in the hepatopancreas and muscle. However, in haemolymph we observed significant variation only in cholesterol and lipid levels. The results suggest that the metabolic variability is related to the stage of maturation of the gonads, in females, where the hepatopancreas and other tissue studies can store and transfer reserves to support maturation to complement the food intake. Variations in the gonadosomatic and hepatosomatic indices suggest that reproduction occurs principally in summer. As in other decapods, abiotic factors such as water temperature, oxygen content, etc. influence the intermediate metabolism.