Does temperature preference relate to the anaerobic capacity of Atlantic cod (Gadus morhua L.) with different haemoglobin phenotype?

The effect of Hb-I* phenotype on white muscle lactate dehydrogenease (LDH, E. C. 1.1.1.27) activity and buffering capacity was studied in Atlantic cod (Gadus morhua), acclimated and measured at temperatures near their behavioral temperature preference. It was hypothesized that these conditions would optimize biochemical processes but no difference was found in LDH activity between the Hb-I* phenotype after 56 d of acclimation to 6 and 14°C. However, LDH activity was both mass- and temperature-dependent; mean activity was 162.2±5.0 and 275.9±6.4 IU g^-1 wet mass (mean±SEM) at 6 and 14°C respectively and larger fish had the highest rate of enzyme activity. White muscle buffer capacity was unaffected by Hb-I* phenotype but higher in cod held at 14°C.     

Drivers of growth for Atlantic cod (Gadus morhua L.) in Icelandic waters – A Bayesian approach to determine spatiotemporal variation and its causes

This study assesses spatiotemporal and sex-specific growth of Atlantic cod Gadus morhua in Icelandic waters. We use a Bayesian approach which lends itself to fitting and comparing nested models such as these. We then compare fitted parameters of these models to potential explanatory variables using a redundancy analysis (RDA) to look for drivers of growth in G. morhua. Results indicate that models that incorporate differences in growth among time, space and sex are the best-fitting models according to deviance information criterion (DIC). Results from RDA indicate that capelin Mallotus villosus recruitment and biomass is highly correlated with deviations in the von Bertalannfy growth parameter k and that L_∞ is correlated with G. morhua landings in the model that uses year to account for time-varying growth and estimated G. morhua recruitment in the model that uses cohort to account for time-varying growth.     

The occurrence of some metazoan parasites of Atlantic cod, Gadus morhua L., in relation to age and sex of the host in Balsfjord (70°N), North Norway

Age and sex differences in the occurrence of some metazoan parasites were investigated in 243 cod (Gadus morhua L.) from Balsfjord, a subarctic fjord in northern Norway. Thirteen species of parasite were studied, comprising seven nematodes, three parasitic copepods, one acanthocephalan, one cestode and one digenean. The nematode Anisakis simplex showed significant increases in both prevalence and mean abundance with host age, while the digenean Hemiurus levinseni showed a significant increase in mean abundance with age. The increases probably result from a long parasite life-span for A. simplex and changes in the feeding pattern of cod with age for H. levinseni. Prevalence of the nematode Contracaecum sp. and mean abundance of the acanthocephalan Echinorhynchus gadi were significantly higher in male than in female cod, whereas mean abundance of H. levinseni was significantly higher in female cod. These results suggest that there may be differences in feeding behaviour between male and female cod in Balsfjord. Accepted: 14 November 1999     

Genetic and morphological variation in Echinorhynchus gadi Zoega in Müller, 1776 (Acanthocephala: Echinorhynchidae) from Atlantic cod Gadus morhua L

Previous studies have shown considerable variability in morphological features and the existence of genetically distinct sibling species in the acanthocephalan Echinorhynchus gadi Zoega in Müller, 1776. The aim of the present study was to follow up and extend those earlier studies by using a combination of DNA analysis and morphometrics to investigate differences between samples of E. gadi from Atlantic cod Gadus morhua L. caught at five fishing grounds in the Baltic Sea and three in different parts of the North Atlantic. Twelve morphological features were measured in 431 specimens of E. gadi, 99 individuals were studied by polymerase chain reaction-restriction fragment length polymorphosm (PCR-RFLP), and selected PCR products were sequenced. The molecular analyses showed the nucleotide sequences of E. gadi rDNA from cod caught at all the sampling sites to be identical. The comparative morphological study, in contrast, revealed significant differences between samples of E. gadi from different sampling sites and showed the separation of E. gadi into two groups corresponding approximately to the systematic classification of cod into the two subspecies, Atlantic G. morhua morhua and Baltic G. morhua callarias. The E. gadi infrapopulation size had a significant effect on some of the morphological features. The results are discussed in relation to cod population biology, the hydrography of the study area and the history of the Baltic Sea formation.     

The isolation of Atlantic cod, Gadus morhua (Gadiformes), populations in Northern Meromictic lakes—A recurrent arctic phenomenon

Although it has previously been considered to be a rare phenomenon, this paper provides evidence of eight occurrences of Atlantic cod in northern coastal saline lakes in Arctic Canada, Greenland, Norway, and Russia. Historic and current habitat features that are necessary for Atlantic cod to colonize and persist in Arctic meromictic lakes are discussed. Data analyses confirm that the persistence of Atlantic cod in Arctic lakes is a recurrent phenomenon, and these populations represent an important component of intraspecific biodiversity. Published in Russian in Voprosy Ikhtiologii, 2008, Vol. 48, No. 2, pp. 179–190. The text was submitted by the authors in English.     

1H, 13C and 15N resonance assignments and second structure information of Gad m 1: a β-parvalbumin allergen from Atlantic cod (Gadus morhua)

Gad m 1 is the major allergen from Atlantic cod. It belongs to β-parvalbumin protein family and is characterized by the presence of two calcium-binding sites so called EF-hand motifs. β-Parvalbumins such as Gad m 1 are the most important fish allergens and their high cross-reactivity is the cause of the observed polysensitization to various fish species in allergic patients. Despite extensive efforts, the complete elucidation of β-parvalbumin-IgE complexes has not been achieved yet. Allergen structural studies are essential for the development of novel immunotherapy strategies, including vaccination with hypoallergenic derivatives and chimeric molecules. Here, we report for the first time the NMR study of a β-parvalbumin: Gad m 1. This report includes: ¹H, ¹³C and ¹⁵N resonance assignments of Gad m 1 as well as the second structure information based on the ¹³C chemical shifts.     

Effects of temperature on egg and larval survival of cod (Gadus morhua) and sprat (Sprattus sprattus) in the Baltic Sea – implications for stock development

Hydrobiologia - Stock development of cod and sprat, two major fish species in the Baltic Sea, is linked by trophic interactions. Depending on recruitment success the Baltic may be pushed towards...     

Walking performance and aerobic and anaerobic metabolism of Carcinus maenas (L.) in sea water at 15°C

Walking performance of the shore crab Carcinus maenas (L.) in sea water at 15 °C was assessed. In large crabs there was an inverse relationship between fatigue time and speed; crabs ran for $\text{\$}\text{?}$10 min at 3.2 m·min^?1 and for only 2 min at 14 m·min^?1. There were linear relationships between oxygen consumption and walking speeds for small and large animals walking at up to 4 m·min^?1 Estimates of maximum oxygen consumption were proportional to W^0.13 whereas inactive consumption is proportional to W^0.44 this resulted in aerobic scope (i.e. the difference between inactive and maximal rates of oxygen consumption) remaining almost constant across a weight range of animals whereas the aerobic expansibility (maximal rates/inactive rates) declined from 7- to 4-fold with increasing size. After a 12-h period without handling (settled animals) the animals could immediately become active and reach maximal rates of oxygen consumption similar to those of animals handled 1 h before the experiment. The aerobic expansibility of these settled animals could range from 21 to 8 times their inactive rates of oxygen consumption in small and large animals respectively. After 10 min of exercise oxygen consumption and whole body lactate levels returned to pre-exercise values within 5 to 25 min. The net oxygen debts range from 16 to 64% of the net oxygen consumption increase during exercise in small and large animals respectively.Calculations of the energy gained from lactate accumulation indicated that the net aerobic energy production during walking was supplemented from 4 to 71 % by anaerobic metabolism in small and large animals respectively. With increasing animal size the decline in aerobic expansibility was offset by an increased capacity for lactate production so that the overall maximum energy production during sustained activity remained almost constant at around seven times the inactive rate. The cost of transport (the net increase in oxygen consumption per g per m) falls with increased walking speed and increased animal size.     

Assessment of the diets of cod Gadus morhua and whiting Merlangius merlangus juveniles in a frontal region close to the Norwegian Trench: co‐existence or competition?

Over 200 pelagic juvenile cod Gadus morhua and whiting Merlangius merlangus were sampled in spring 2001 at stations inside and outside a frontal region close to the Norwegian Trench, and their stomach contents analysed in the context of zooplankton samples taken at the same time and same locations. Merlangius merlangus juveniles appeared to feed on a diverse zooplankton community, whereas G. morhua juveniles appeared to preferentially select Pseudocalanus elongatus, even though these prey items were not the dominant component of the prey community. The results suggest that during the pelagic juvenile stage, M. merlangus and G. morhua are direct competitors for zooplanktonic prey. In addition, because M. merlangus are more opportunistic, they may be more tolerant to changes in the species composition of the prey community, and therefore out‐compete G. morhua juveniles at times of low preferred prey abundance or under changing environmental conditions.     

Stress-Induced Reversion to Virulence of Infectious Pancreatic Necrosis Virus in Na?ve Fry of Atlantic Salmon (Salmo salar L.)

We have studied stress-induced reversion to virulence of infectious pancreatic necrosis virus (IPNV) in persistently infected Atlantic salmon (Salmo salar L.) fry. Naïve fry were persistently infected with a virulent strain (T₂₁₇A₂₂₁ of major structural virus protein 2, VP2) or a low virulent (T₂₁₇T₂₂₁) variant of IPNV. The fry were infected prior to immunocompetence as documented by lack of recombination activating gene-1, T-cell receptor and B-cell receptor mRNA expression at time of challenge. The fish were followed over 6 months and monitored monthly for presence of virus and viral genome mutations. No mutation was identified in the TA or TT group over the 6 months period post infection. Six months post infection TA and TT infected groups were subject to daily stress for 7 days and then sampled weekly for an additional period of 28 days post stress. Stress-responses were documented by down-regulation of mRNA expression of IFN-α1 and concomitant increase of replication levels of T₂₁₇T₂₂₁ infected fish at day 1 post stress. By 28 days post stress a T221A reversion was found in 3 of 6 fish in the T₂₁₇T₂₂₁ infected group. Sequencing of reverted isolates showed single nucleotide peaks on chromatograms for residue 221 for all three isolates and no mix of TA and TT strains. Replication fitness of reverted (TA) and non-reverted (TT) variants was studied in vitro under an antiviral state induced by recombinant IFN-α1. The T₂₁₇A₂₂₁ reverted variant replicated to levels 23-fold higher than the T₂₁₇T₂₂₁ strain in IFN-α1 treated cells. Finally, reverted TA strains were virulent when tested in an in vivo trial in susceptible salmon fry. In conclusion, these results indicate that stress plays a key role in viral replication in vivo and can facilitate conditions that will allow reversion from attenuated virus variants of IPNV.     

Effects of sea lice (Lepeophtheirus salmonis Kröyer, 1837) infestation on macrophage functions in Atlantic salmon (Salmo salar L.)

Experiments were conducted to determine the effects of sea lice, Lepeophtheirus salmonis, on non-specific defence mechanisms in Atlantic salmon, Salmo salar, by experimentally infesting hatchery-reared 1 and 2 year old post-smolts, S1 and S2, with laboratory grown infective copepodids at moderate to high infection intensities ranging from 15-285 lice per fish. The effects of sea lice-induced stress were investigated by measuring the blood levels of cortisol and glucose as indicators of primary and secondary stress responses, and by changes in macrophage respiratory burst activity and phagocytosis as indicators of tertiary stress responses as well as non-specific defence mechanisms. Fish were sampled prior to sea lice infestation at day 0 and at days 3, 7, 14 and 21 post-infestation. Sea lice were at copepodid stage at day 3, at chalimus stages at days 7 and 14, and at pre-adult stage at day 21. Blood levels of cortisol and glucose were found to be significantly increased at day 21 in fish-infested with the highest levels. Macrophage respiratory burst and phagocytic activities were found to be significantly decreased only at day 21. These results indicate that sea lice do not suppress host defence mechanisms during the earlier stages of infestation. They do have effects on the development of chronic stress and on the host non-specific defence mechanisms soon after the lice reach the pre-adult stage.     

Physiological responses to cold (10° C) in men after six months' practice of yoga exercises

A study was conducted on 30 healthy soldiers (age: 40–46 years) to assess the effect of selected yogic exercises (asanas) on some physiological responses to cold exposure. They were randomly divided into two groups of 15 each. One group performed regular physical exercises of physical training (PT), while the other group practised yogic exercises. At the end of 6 months of training, both the groups were exposed together to cold stress at 10°C for 2 h, and the following parameters were periodically monitored during cold exposure: heart rate (fH), blood pressure (BP), cardiac output , oral temperature (T_or), skin temperature (T _sk), respiratory rate (fR), minute ventilation , oxygen consumption , and shivering response by integrated electromyogram (EMG). There were progressive increases inBP, fR, , , and and decreases infH,T _or andT _sk during cold exposure in both the groups. However, the decrease inT _or and the increases in and were relatively lower (P<0.01) in the yoga group as compared to the PT group. The shivering response appeared much earlier and was more intense in the PT group. These findings suggest that practice of yoga exercises may improve cold tolerance.     

Pharmacological Activity of Ruthenium Complexes trans-[RuCl2(L)4] (L = Nicotinic or i-Nicotinic acid) on Anxiety and Memory in Rats

Many biological properties have been attributed to ruthenium complex I (trans-[RuCl₂(nic)₄]) and ruthenium complex II (trans-[RuCl₂ (i-nic) ₄]) including nitric oxide synthase inhibition. In this study, we evaluated pharmacological effects of these complexes on anxiety and memory formation. Memory was evaluated with inhibitory avoidance and habituation to an open-field and anxiety was tested with elevated plus-maze. Adult male Wistar rats (250 to 350 g) received intraperitoneal injections of vehicle, ruthenium complex I (45.2, 90.4, or 180.7 μmol/kg), or ruthenium complex II (0.08, 4.5, or 13.6 μmol/kg) 30 min prior open-field training or elevated plus-maze test and 30 min or 0 h after training. No effects were observed in the anxiety parameters and habituation to an open-field. The ruthenium complexes impaired memory retention compared with vehicle group in the inhibitory avoidance, as when administrated 30 min prior as immediately after training. The memory impairment induced by ruthenium complexes may be due to their nitric oxide synthase inhibition capacity.     

Anaerobic metabolism of goldfish,Carassius auratus (L.): Ethanol and CO2 excretion rates and anoxia tolerance at 20, 10 and 5°C

• 1.1. Goldfish acclimated to 20, 10 and 5°C were exposed to anoxia. The lethal thresholds expressed as median lethal time (LT₅₀) were found to be 22, 65 and 45 hr respectively.
• 2.2. During anoxia excretion of CO₂ and ethanol was monitored. CO₂/ethanol ratios were initially far over unity, falling to lower values after longer exposures.
• 3.3. The quantitative aspects of ethanol production seem incompatible with the availability of glycogen as a carbon source. Protein is suggested as a possible substrate.

     

Influence of water temperature and waterborne cadmium toxicity on growth performance and metallothionein–cadmium distribution in different organs of Nile tilapia,Oreochromis niloticus (L.)

Cadmium (Cd) is believed to be one of the most abundant and ubiquitously distributed toxins in the aquatic system. This metal is released to the aquatic environment from both anthropogenic sources, such as industrial, agricultural and urban effluents as well as natural sources, such as rocks and soils. Otherwise, the temperature increase of water bodies, which has been observed due to global climatic changes, has been shown to increase Cd toxicity for several aquatic animal species including fish. In the present study, Nile tilapia, Oreochromis niloticus (L.), (26.0±0.38 g) were reared at 20, 24, 28, or 32 °C and exposed to 0.0 or 0.5 mg Cd/L for 8 weeks to investigate effects of water temperature, Cd toxicity and their interaction on fish performance as well as metallothionein (MT) and Cd distribution in different fish organs. It was found that fish reared in Cd-free group at 28 °C showed the optimum growth and feed intake, while Cd-exposed fish showed low growth and feed intake irrespective to water temperature. A synergetic relationship between water temperature and Cd toxicity was observed where Cd toxicity increased as water temperature increased and the worse growth was obtained in Cd-exposed fish reared at 32 °C. Additionally, the highest Cd residues in different fish organs were detected in Cd-exposed fish reared at 32 °C. Similarly, MT concentrations in different fish organs increased as water temperature increased especially in Cd-exposed fish groups. A high positive correlation between MT and Cd concentrations in fish organs was detected. The distribution of MT and Cd levels was in the order of liver>kidney>gills>muscles. The present study revealed that the optimum water temperature suitable for Nile tilapia growth is 28 °C. Additionally, Cd exposure had a deteriorate effect on the growth and health of Nile tilapia. This hazardous effect increased as water temperature increased. Further, liver and kidney were the prime sites of Cd accumulation, while Cd load in the muscles was the lowest as compared to the other investigated organs.     

Branch development in custard apple (cherimoya Annona cherimola Miller × sugar apple A. squamosa L.) in relation to tip-pruning and flowering, including effects on production

Custard apple has cryptic axillary buds, hidden from view by the base of the petiole. This has led to confusion about custard apple’s flowering habit. Flowering only occurs during early branch development, and can be forced at any time of the growing season simply by removing leaves. Here, we show that flowering is terminal, not extra-axillary, and that the apparent continuation of the main stem beyond the flower is, instead, a sympodial branch. Secondary (including sympodial) branching only occurs during early branch development. Thereafter, axillary bud release is inhibited by the subtending leaf. Here, we show that summer tip-pruning of all branches arrests canopy development until the following spring owing to this inhibition. Although summer tip-pruning prevented new vegetative growth in the canopy, fruit size decreased relative to the control trees by ca. 23%. The reason for this decrease was probably related to increased carbon limitation to growth given that dawn water soluble and total non-structural carbohydrate concentrations were lower in the tip-pruned trees. Thus, it appears that the reduced competition between fruit development and new vegetative growth in the tip-pruned trees was more than matched by lower photosynthetic capacity in the arrested canopy. Trees grown inside a shade-house were more vigorous than those grown outside. The difference in vigour had little effect on fruit size.