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Abstract: Pulsed field gradient spin echo NMR spectroscopy was used to measure diffusion coefficients of the α-helical type I antifreeze protein from the winter flounder, two synthetic derivatives in which the four Thr residues were replaced with Val and Ala, respectively, and the low molecular weight fraction antifreeze glycoprotein. Under the conditions studied, the natural type I antifreeze protein and low molecular weight glycoprotein gave diffusion values that were consistent with the presence of monomeric protein in solution. While significant aggregation of the Ala analogue was observed (2–10mM), there was no evidence for aggregation in the Val analogue (1–3mM). These results are compared with previously reported solubility and thermal hysteresis data and the implications for the design of synthetic antifreeze proteins are discussed. [Copyright &y& Elsevier]

Abstract: We made a single intraperitoneal (IP) injection of morphine sulfate (40mg/kg) into winter flounder and seawater acclimated rainbow trout at 10°C and then followed its disposition by measuring the change in plasma morphine concentration for 100h using a morphine specific ELISA. Disposition also was followed for 6h after a single IV injection of 7.5mg morphine sulfate in winter flounder. Plasma morphine reached a maximum within an hour post-injection IP and then decreased in a bi-exponential fashion with a rapid distribution phase followed by a slower elimination phase. The disposition was slower in flounder than in trout even though the fish were held at the same temperature. For example, plasma clearance was 76mL h− 1 kg− 1 in the flounder but was almost twice as much in the trout (153mL h− 1 kg− 1) and mean residence time was 27.9h in the flounder but was 7.0h in the trout. The present study is the first comprehensive pharmacokinetic analysis for any analgesic in an ectotherm, and our results show that: 1) significant intra-specific variation exists between fishes: and 2) the disposition of morphine in fish is approximately one order of magnitude slower than it is in mammals. These differences may be due in part to mass specific differences in cardiac output. [Copyright &y& Elsevier]

This study assessed the effects of discharges from a sulphite-bleaching paper mill on winter flounder ( Pleuronectes americanus) sampled each spring over a 5-year period in St. George’s Bay, Newfoundland, prior to foraging activity. The fish were captured by SCUBA divers near the mill and at a reference site 10 km up current. Several bioindicators were used to assess fish health. Larger and older flounder exhibiting gross and microscopic tissue lesions, lower condition factor, and elevated hepatosomatic index but lower gonadosomatic index that was associated with delayed development, were observed in samples caught near the mill compared to those at the reference site. Additionally, fish examined near the mill were infested with an ectoparasite, Cryptocotyle lingua, that causes black spot disease but harbored fewer numbers of a digene, Steringophorus furciger, in the digestive tract than samples taken at the reference site. These results suggest that abnormal size distribution, interruption of growth, high prevalence of lesions, lower condition factor, enlarged liver, delayed gonadal development, and differences in parasitic levels were indicative of stress in winter flounder caused by discharges from the mill compared to samples from a reference site. There was no evidence of a population decline in the inlet because of annual recruitment possibly from St. George’s Bay into which it opens. [ABSTRACT FROM AUTHOR]

Abstract: Species selectivity of two types of low height experimental gillnets, 8mesh deep (MD) and 12MD, was compared with that of the standard cod gillnet (25MD) and the tie-down flounder gillnet in inshore waters of the western Gulf of Maine. The experiment was designed to investigate whether using the lower nets could reduce the catch of the Atlantic cod (Gadus morhua) while maintaining comparable catch of flounders. The results indicate that the 8MD experimental net caught significantly less cod than the standard cod net (t-test, P <0.001), the tie-down flounder net (t-test, P <0.05), and the 12MD experimental net (P <0.001). The size of cod caught by the tie-down nets was significantly smaller than those by the 8MD or 12MD nets (P <0.05). The 8MD net caught marginally more flounders (combined number of yellowtail flounders, Limanda ferruginea, American plaice, Hippoglossoides platessoides, witch flounder, Glyptocephalus cynoglossus, and winter flounder, Pleuronectes americanus) than the standard cod net (P =0.05), but significantly less than the tie-down net (P <0.001). There are no significant differences in flounder catch rates between the 8MD net and the 12MD net (P >0.05). In addition, the tie-down net caught twice as much monkfish, Lophius americanus, sea raven, Hemitripterus americanus, and rock crab, Cancer irroratus, three times more American lobsters, Homarus americanus, and four to eight times more thorny skates, Amblyraja radiata, than the other three types of nets. On the other hand, the standard cod net caught significantly more spiny dogfish, Squalus acanthias, and white hake, Urophycis tenuis, than the other three nets (P <0.001). While further experiments are still needed in different fishing areas and seasons, the 8MD low profile nets have great potential to substitute the standard cod net to maintain flounder catch rates while reducing the catch of cod. [Copyright &y& Elsevier]

Provides information on a study which examined the effects of transport density on cortisol levels in juvenile winter flounder, or Pseudopleuronectes americanus. Details of cortisol extraction and radioimmunoassay; Occurrence and consequent physiological responses of juvenile flounders to stress; Recommendation to ensure the successful transport of the species from the hatchery to the wild.

Abstract: The winter flounder (Pseudopleuronectes americanus) antimicrobial peptide pleurocidin was produced in Escherichia coli using a synthetic gene constructed by PCR. The gene expresses pleurocidin from pET21a fused to the C-terminus of an insoluble carrier peptide. Once expressed, the fusion peptide formed inclusion bodies in the cytoplasm that were collected, solubilized in guanidine–HCl, and chemically cleaved using hydroxylamine at a unique asparaginyl-glycyl dipeptide. This released recombinant pleurocidin (r-pleurocidin), which was purified using ultrafiltration followed by reverse phase chromatography. The r-pleurocidin peptide resolved as a single band (2.7kDa) when analyzed by Tris–Tricine buffered SDS–PAGE, and its amino acid sequence was confirmed using tandem mass spectrometry. Extending the pleurocidin sequence with a C-terminal glycine (r-pleurocidin-G) suppressed production of the fusion peptide 15-fold. When pleurocidin was extended further to include aspartate (r-pleurocidin-GD), the same effect was observed, and when pleurocidin was extended with aspartate alone, no effect was observed. Expression of fusion peptide containing either r-pleurocidin-G or r-pleurocidin-GD with low concentrations of inductant caused E. coli to enter stationary phase prematurely, but did not affect overall growth rates. A partial production recovery of r-pleurocidin-G was achieved by inducing expression in stationary phase cells. We observed r-pleurocidin-G to have enhanced antimicrobial activity compared with r-pleurocidin, and we propose that this activity interferes with E. coli metabolism during expression. This antimicrobial effect is probably facilitated by residual solubility of the fusion peptide and by a C-terminal cap structure, which stabilizes the r-pleurocidin-G α-helix that is thought to be important for activity. [Copyright &y& Elsevier]

Metamorphosis is a critical developmental stage in marine fish species, but mortalities are also elevated at the settling phase. Our objective was to evaluate the effects of different rearing systems and larval diets on survival, general condition and pigmentation of newly settled winter flounder ( Pseudopleuronectes americanus) juveniles. At settlement, winter flounder juveniles were reared in two different types of tanks (plankton kreisel and rectangular raceway). The early juveniles were followed for 1 month and their condition was evaluated using biochemical indices. Juveniles did not show signs of fin rot and pigmentation was well developed, but they had different RNA/DNA ratios. This study highlights the fact that rearing conditions at the onset of the juvenile stage may be critical for successful juvenile production. [ABSTRACT FROM AUTHOR]

Abstract: Wild stocks of winter flounder (Pseudopleuronectes americanus) in the Northwestern Atlantic have been depleted to an extent that has warranted increasingly stronger fishing regulations in the last decade. As a means to strengthen the wild populations of winter flounder and to avoid further fishing restrictions, the rearing of juvenile fish in hatcheries for release in coastal waters has been viewed as a possibility. Many fishery biologists have concern that hatchery-reared fish are not behaviorally and/or physiologically equipped to survive in the wild due to a lack of predator interaction and conditioning. This study aimed to determine whether hatchery-reared juvenile winter flounder exhibited a stress response, as evidenced by an increase in whole-body cortisol concentrations, to cohabitation with potential predators. The green crab (Carcinus maenas) and sand shrimp (Crangon septemspinosa) have been implicated as sources of juvenile flounder mortality in laboratory and field studies and therefore were chosen as invertebrate predators. In addition, the summer flounder (Paralichthys dentatus) was selected as a predator because of its co-existence with young winter flounder in estuaries during early summer. Juvenile fish (n =12) were exposed to predators for 24 h in an arena. Results from radioimmunoassay indicate that juvenile winter flounder initiate a cortisol response to sand shrimp and summer flounder cohabitation, whereas the presence of a green crab does not elicit such a response. The ability of a fish to detect and react to a predator is vital for survival to a reproductive size. This study demonstrates that a hatchery-reared juvenile winter flounder can mount a stress response in the presence of predators. [Copyright &y& Elsevier]

Abstract: Predation on flatfish during the early juvenile stage is an important factor regulating year-class strength and recruitment. In this study, immunological dietary analysis was performed on green crabs (Carcinus maenas) collected from the Niantic River, Connecticut, in an effort to evaluate the predatory impact of this species on post-settlement winter flounder (Pseudopleuronectes americanus). Through the use of species-specific antiserum, winter flounder proteins were identified in 4.8% of the green crab stomachs analyzed (n =313, size range=14–74 mm carapace width, CW), revealing that crabs ≥29 mm CW are predators of post-settlement winter flounder in natural populations. The most significant factor underlying the predator–prey interaction was the relative size relationship between species, such that the incidence of winter flounder remains in the stomach contents of green crabs was positively correlated with predator-to-prey size ratio. Results from dietary analysis were incorporated into a deterministic model to estimate the average daily instantaneous mortality and cumulative mortality of winter flounder owing to green crab predation. Accordingly, green crabs may account for 0.4% to 7.7% (mean=2.2%) of the daily mortality of winter flounder and consume 1.1% to 32.3% (mean=10.2%) of the flounder year-class. Model simulations further indicate that variations in green crab abundance and size-structure account for the greatest variability in winter flounder mortality. Relative to other macro-crustacean predators, however, predation by green crabs has a minimal effect on winter flounder survival, due in large part to the low densities of these crabs in temperate estuaries. [Copyright &y& Elsevier]

One of the main elements in developing an optimal release strategy for an enhancement effort is to evaluate and select release sites that will support growth and survival of newly released, cultured fish. Three potential release sites (New Castle (NC), Broad Cove (BC) and Oyster River (OR)) in the Great Bay Estuary, NH, USA were evaluated for pilot-scale releases of winter flounder ( Pseudopleuronectes americanus Walbaum). Cultured juvenile flounder were placed in cages at each of the three sites. Sites were evaluated based on growth and survival of the fish in relation to water temperature, prey availability and sediment composition. Fish grew faster in the two upper estuarine sites BC (0.54 mm day−1) and OR (0.56 mm day−1) than at the site at the mouth of the estuary (NC=0.37 mm day−1). Fish survival (44–53%) and water temperature (17.8–19.7°C) did not vary between sites. Benthic samples showed that prey was available to, and eaten by, the flounder. Sediment composition was the main difference between the three sites, with one site (NC) characterized by gravel whereas the other two sites were sandy. These results corroborate other studies showing the importance of sediment quality for the distribution of flatfish populations. From these results, we can confidently eliminate NC as a potential release area and recommend that sandy sites are better for stocking cultured juvenile winter flounder than gravely sites. [ABSTRACT FROM AUTHOR]

Abstract: Pseudopleuronectes americanus is a Northern teleost species that produces antifreeze proteins (AFPs) to protect them from freezing during the winter. These AFPs bind to ice crystals to inhibit their growth, and they also protect cell membranes at low temperatures. In this study, vitrification trials were done with fish embryos at three different developmental stages, using two different protocols for incorporating the vitrifying solutions. Toxicity of the cryoprotectants and permeability to dimethyl sulfoxide were analyzed. Embryos were vitrified in 0.5ml straws by direct immersion in liquid nitrogen, and their morphology and development analyzed following thaw. The embryos responded well to vitrification as evidenced by the high percentage that exhibited good morphology following thaw. Although none of the embryos hatched, a small percentage (0.92%) of them showed active movements within the chorion and continued to develop for a number of days following thaw. This is the first record of post-thaw development of vitrified fish embryos. [Copyright &y& Elsevier]

We evaluated the influence of environmental factors on recruits per spawner (RS) anomalies of 12 New England groundfish stocks. Nonparametric methods were used to analyse time-series of RS anomalies derived from stock-recruitment data in recent assessments. The 12 stocks occur in three geographic regions: the Gulf of Maine (cod Gadus morhua, redfish Sebastes fasciatus, winter flounder Pseudopleuronectes americanus, American plaice Hippoglossoides platessoides, witch flounder Glyptocephalus cynoglossus, and yellowtail flounder Limanda ferruginea), Georges Bank (cod, haddock Melanogrammus aeglefinus, and yellowtail flounder), and Southern New England (summer flounder Paralichthys dentatus, yellowtail flounder, and winter flounder). Randomization tests were applied to detect years when RS anomalies were unusually high or low for comparison with oceanographic conditions such as the 1998 intrusion of Labrador Subarctic Slope water into the Gulf of Maine region. Randomization methods were also used to evaluate the central tendency and dispersion of all RS anomalies across stocks. Average RS anomalies were significantly positive in 1987 across stocks and regions, indicating that environmental forcing was coherent and exceptional in that year. Responses of RS values of individual stocks to lagged and contemporaneous environmental variables such as the North Atlantic Oscillation (NAO) index, water temperature, windstress, and shelf water volume anomalies were evaluated using generalized additive models. Overall, the NAO forward-lagged by 2 years had the largest impact on RS anomalies. This apparent effect is notable because it could provide a leading indicator of RS anomalies for some commercially exploited stocks. In particular, the three primary groundfish stocks on Georges Bank (cod, haddock, and yellowtail flounder) all exhibited positive RS anomalies when the NAO2 variable was positive. [Copyright &y& Elsevier]

The recent discovery of a large hyperactive antifreeze protein in the blood plasma of winter flounder has helped explain why this fish does not freeze in icy seawater. The previously known, smaller and much less active type I antifreeze proteins cannot by themselves protect the flounder down to the freezing point of seawater. The relationship between the large and small antifreezes has yet to be established, but they do share alanine-richness (> 60%) and extensive α-helicity. Here we have examined two other righteye flounder species for the presence of the hyperactive antifreeze, which may have escaped prior detection because of its lability. Such a protein is indeed present in the yellowtail flounder judging by its size, amino acid composition and N-terminal sequence, along with the previously characterized type I antifreeze proteins. An ortholog is also present in American plaice based on the above criteria and its high specific antifreeze activity. This protein was purified and shown to be almost fully α-helical, highly asymmetrical, and susceptible to denaturation at room temperature. It is the only detectable antifreeze protein in the blood plasma of the American plaice. Because this species appears to lack the smaller type I antifreeze proteins, the latter may have evolved by descent from the larger antifreeze. [ABSTRACT FROM AUTHOR]

This study estimated rates of sand shrimp (Crangon septemspinosa) predation on winter flounder (Pseudopleuronectes americanus) eggs and examined the effect of temperature on density-dependent mortality of early-stage flounder. In laboratory experiments, shrimp feeding rates on flounder eggs were positively correlated with temperature and shrimp size. Immunological assays of shrimp stomach contents indicated that 7.2% of shrimp collected from the Niantic River (Connecticut) had flounder eggs in their stomachs. Incidence of egg predation was highest in February (20%) and decreased continuously into early April (1.2%). In a deterministic model simulating predator-induced mortality of flounder eggs during a spawning season, shrimp consumed 0.4%–49.7% of the total flounder spawn. Variations in shrimp population abundance and size structure accounted for the greatest variability in egg mortality. Water temperature during the spawning season presumably alters the population dynamics of early-stage flounder. In a long-term survey, the number of yolk-sac flounder larvae in warm years (≥4.3 °C) was depressed at high egg densities, indicating strong compensatory processes that increased egg mortality and limited the abundance of larvae. Failure of flounder to produce strong year-classes of larvae during warm years, possibly resulting from altered trophic dynamics, may explain the inability of stocks to recover from previous overexploitation. ..LAN-FR Nous estimons dans notre étude les taux de prédation de la crevette des sables (Crangon septemspinosa) sur les oeufs de la plie rouge (Pseudopleuronectes americanus) et évaluons les effets de la température sur la mortalité dépendante de la densité chez les premiers stades de la plie. Dans des expériences de laboratoire, il y a une corrélation positive entre les taux d'alimentation des crevettes sur les oeufs de plie, d'une part, et la température et la taille des crevettes, d'autre part. Des tests immunologiques sur les estomacs des crevettes récoltées dans la Niantic (Connecticut) révèlent que 7,2 % des estomacs contiennent des oeufs de plie. La fréquence de la prédation des oeufs est maximale en février (20 %) et décroît graduellement jusqu'au début d'avril (1,2 %). Un modèle déterministe qui simule la mortalité des oeufs de plie due aux prédateurs durant la saison de reproduction indique que les crevettes consomment 0,4–49,7 % de l'ensemble de la ponte des plies. Les variations d'abondance et la structure de taille de la population de crevettes expliquent la plus grande partie de la variabilité de la mortalité des oeufs. La température de l'eau durant la saison de reproduction modifie sans doute la dynamique de population des plies de premiers stades. Dans une étude à long terme, le nombre de larves vésiculées de plies, les années d'eau plus chaude (≥4,3 °C), est réduit aux fortes densités d'oeufs, ce qui indique qu'il y existe d'importants processus compensatoires qui augmentent la mortalité des oeufs et limitent l'abondance des larves. L'incapacité des plies à produire des classes d'âge plus importantes les années chaudes, qui résulte peut-être d'un changement trophodynamique, peut expliquer pourquoi les stocks ne réussissent pas à se remettre de la surexploitation du passé.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

Pleurocidin is an antimicrobial peptide that was isolated from the mucus membranes of winter flounder (Pseudopleuronectes americanus) and contributes to the initial stages of defense against bacterial infection. From NMR structural studies with the uniformly 15N-labeled peptide, a structure of pleurocidin was determined to be in a random coil conformation in aqueous solution whereas it assumes an α-helical structure in TFE and in dodecylphosphocholine (DPC) micelles. From 15N relaxation studies, the helix is a rigid structure in the membrane-mimicking environment. Strong NOESY cross-peaks from the pleurocidin to the aliphatic chain on DPC confirm that pleurocidin is contained within the DPC micelle and not associated with the surface of the micelle. From diffusion studies it was determined that each micelle contains at least two pleurocidin molecules. [ABSTRACT FROM AUTHOR]

The winter flounder (Pseudopleuronectes americanus) produces short, monomeric α-helical antifreeze proteins (type I AFP), which adsorb to and inhibit the growth of ice crystals. These proteins alone are not sufficiently active to protect this fish against freezing at -1.9 °C, the freezing point of seawater. We have recently isolated a hyperactive antifreeze protein from the plasma of the flounder with activity 10-100-fold higher than type I AFP. It is comparable in activity to the AFPs produced by insects, and is capable of conferring freeze resistance to the flounder. This novel AFP has a molecular mass of 16,683 Da and a remarkable amino acid composition that is >60% alanine. CD spectra indicate that the protein is almost entirely α-helical at 4 °C but partially denatures at 20 °C, resulting in a species with a moderately reduced helix content that is stable at up to 50 °C. This transformation correlates with irreversible loss of activity. Analytical ultracentrifugation (sedimentation velocity and equilibrium) indicates that the predominant species in solution is dimeric (molecular weight, 32,275). Size-exclusion chromatography reveals a 2-fold higher apparent molecular weight suggesting that this molecule has an unusually large Stokes radius. The axial ratio of the dimer calculated from the sedimentation velocity data is 18:1, confirming that this protein has an extraordinarily long, rod-like structure, consistent with a novel dimeric α-helical arrangement. The structural model that best fits these data is one in which the ∼195 amino acids of each monomer form one ∼290-Å, long α-helix and associate via a unique dimerization motif that is distinct from that of the leucine zipper and any other coiled-coil. [ABSTRACT FROM AUTHOR]

Discriminant function analyses of infection parameters of parasitic helminths revealed that abundances of seven helminth species contributed significantly to the delineation of four host populations of winter flounderPleuronectes americanusfrom the central and south-west Scotian Shelf and the north-east Gulf of Maine(NAFO subdivision 4WX-5Z). These were adult digeneans,Derogenes varicus,Genolinea laticauda,Steganoderma formosumandSteringophorus furciger, metacercariae of the digenean,Stephanostomum baccatum, and larval nematodes,Anisakis simplexandHysterothylacium aduncum. The correct classification rate was 84% overall, with Georges Bank(5Z) and Sable Island Bank(4W) winter flounder being the most accurately classified samples at 98 and 88%, respectively. Winter flounder from south-west Nova Scotia(4X), an inshore sample from St Marys Bay and offshore fish from Browns Bank, had the lowest rates of correct classification(76 and 71%, respectively) due, primarily, to cross-misclassification between the two samples. Winter pairwise comparisons of four microsatellite markers identified significant genetic differences between all populations sampled with the Georges Bank population being the most genetically distinct overall, and St Marys Bay and Browns Bank fish being the least dissimilar. [ABSTRACT FROM AUTHOR]

The article focuses on letters that were written by the eminent biologist George C. Williams to the author. During the 1960s and 1970s, George conducted research on sand land and tautog and cunner eggs, the bathymetric distribution of fish eggs, the natural mortality rates of cunner eggs, and the embryogenesis of winter flounder eggs. The laboratory rearing experiments were two-factor, factorial designs covering the range of those variables measured in the field. In his last letter to George, the reported good news about the field sampling and his laboratory experiments on the development rates of menhaden eggs. George's August 16, 1973 letter provides a documented example of how George's ideas influenced the author's research.

Abstract: Effluent upgrades for metropolitan Boston have included toxicant reduction, primary and secondary treatment and outfall extension. Between 1992 and 2003 winter flounder at five stations were surveyed annually for liver and muscle burden and chronic hepatic sub-lethal impacts of polynuclear and halogenated aromatic hydrocarbons, and metals. Trends in flounder availability and fin condition were also examined. In 1988 12% of the adult winter flounder in Boston Harbor exhibited hepatic neoplasms and up to 80% had hepatic hydropic vacuolation (HV). Tumor prevalence fell to 0–2% and HV to &#60;50% by 1996. Since then tumors have been absent, while a steady prevalence of HV has persisted, consistent with lower hydrocarbon loading and tissue levels. Contaminants and HV also fell with distance from the Boston outfall. After the outfall extension was activated in 2000, there has been no significant change in flounder liver health at the new outfall site. [Copyright &y& Elsevier]

Indices of energy reserves may represent interesting parameters that can be used as bioindicators in environmental studies. The goal of this study was to identify a water-energy model that could predict energy reserves in winter flounder Pseudopleuronectes americanus. Winter flounder kept in captivity and fed different food types (either capelin Mallotus villosus or Atlantic herring Clupea harengus, amphipods Anonyx sarsi, and wet pellets) for 2, 5, and 14 months and wild fish captured in May, July, and October were used to show a large range in energy content. High levels of correlation were observed between water and energy contents in fish carcasses (r² = 0.82) and muscle (r² = 0.75). However, the biochemical composition of the liver remained relatively constant, despite changes in the hepatosomatic index. The condition factor (somatic weight/length³) was associated with energy reserves (i.e., water contents), but the coefficients of determination were smaller (0.18 < r² < 0.34). We found that muscle water content, which can easily be determined, is an efficient way to accurately predict energy reserves in winter flounder. [ABSTRACT FROM AUTHOR]

Abstract: 4-Nonylphenol (4-NP), a major by-product of alkylphenol ethoxylates, is used in several industries and as a consequence is quite common in rivers, estuaries and other aquatic environments that receive sewage discharges or are near offshore oil platforms. 4-NP is an environmental estrogen that also binds human and rodent Pregnane X-receptor (PXR), the orphan nuclear receptor that controls the expression of several detoxication genes in mammals, including several CYP3A and CYP2B family members. These P450s preferentially hydroxylate testosterone in the 6β- and 16β-positions, respectively. In this study, the effects of 4-NP on testosterone metabolism and hepatic CYP3A induction were compared to the effects of St. John''s Wort (SJW), a well established mammalian PXR agonist, in winter flounder. Male winter flounder (Pleuronectes americanus) were injected with 100 mg/kg/day 4-NP or 500 mg/kg/day SJW or both (S and N) every 24 h. Forty-eight hours after the initial injections, flounder were euthanized. Western blots and testosterone 6β-hydroxylation indicated that CYP3A was increased 50% by 4-NP, but was not affected by SJW. Testosterone 16β-hydroxylase activity was also significantly increased in flounder treated with 4-NP (2.8×), but not with SJW. This is not consistent with our hypothesis that both SJW and 4-NP would induce CYP3A. Subtractive hybridization was performed between control and 4-NP treated hepatic mRNA samples to isolate differentially expressed genes. Subtractive hybridization indicated that several acute phase proteins were altered by 4-NP. Quantitative real-time PCR (Q-PCR) confirmed 4-NP altered the expression of complement components C8b, cathepsin L, C-type lectin domain, FK506 binding protein 2 precursor (FKBP2) and an EST (expressed sequence tag). SJW and 4-NP treated flounder demonstrated similar induction profiles for the EST, cathepsin L and FKBP2, suggesting that SJW was at a sufficient dose to alter gene expression but not induce P450s. In conclusion, testosterone hydroxylase activity and Western blots indicate that SJW did not activate detoxication pathways in a similar manner to 4-NP. [Copyright &y& Elsevier]

In vitroexperiments were performed on melanophores on scales carrying small slips of skin(scale slips) sampled from the white spot, dark band and general background components of patterning in winter flounderPseudopleuronectes americanus.In vitro, forskolin(10−4 to 10−7 M) was employed to increase melanophore intracellular cytosolic adenosine-3′-5′-monophosphate(cAMP) levels by stimulating adenylate cyclase. Such increase shifted noradrenaline concentration-response curves to the right, general background melanophores being least sensitive to the forskolin, indicating a relatively higher proportion ofα2-adrenoceptors, and those from white spots the most sensitive. Melanosome dispersion, in balanced salt solution, was also enhanced by such raised levels of cAMP. Without forskolin, melanophores from white spots displayed the shortest pigment dispersion time in balanced salt solution, the slower melanophores from the other pattern components being those most affected by the addition of forskolin. The results demonstrate that differences in melanophore physiological responsiveness associated with flatfish patterns involve differential intracellular levels of cAMP, as well as differences in melanophore size and rates of melanosome movement. [ABSTRACT FROM AUTHOR]

Laboratory experiments were performed with cultured and wild juvenile winter flounderPseudopleuronectes americanusto evaluate differences in behaviour and adaptation affecting post-release vulnerability to predation. Studies revealed that the cryptic abilities of cultured winter flounder increased over time. Sediment-naïve, cultured fish required a minimum of 2 days to improve their burying skills and at least 90 days for colour adaptation to match the sediment. Cultured winter flounder selected sediments consisting of small grains and colours matching their own pigment. Cultured winter flounder, regardless of their colour, were significantly more vulnerable to predation by birds. Additionally, cultured fish reacted differently than wild winter flounder when exposed to cues from a potential predator. [ABSTRACT FROM AUTHOR]

Synthetic-based oil drilling fluids are currently used by drilling rigs offshore to reduce risks in removing petroleum from depths beneath the ocean floor. There is a generally accepted view that drilling fluids that contain aliphatic hydrocarbons possess considerably less toxicity than polycyclic hydrocarbons which are known to produce adverse affects (Neff and Anderson 1981). However, some drilling fluids and mud tend to be toxic to benthic communities whereas others produce only subtle effects (GESAMP 1993; Breuer et al. 2004 and references therein). The latter reports and others have revealed that major effects were apparent only within 250-500 m of the rigs but subtle effects were observed up to 5000 m from development sites in the North Sea (Olsgard and Gray 1995). A synthetic based drilling fluid (IA-35) is currently used in the Newfoundland offshore. Toxicity studies conducted on scallops (Placopecten megallanicus), plankton, fish larvae and winter flounder (Pleuronectes americanus) suggested a low potential for acute toxicity (Cranford et al. 2000: Armsworthy et al. 2001, Payne et al. 2001a). Additional studies on Microtox and amphipod bioassays suggested that the synthetic fluid cuttings also exhibited a low acute potential (Payne et al. 2001b). The Hibernia drilling platform off coastal Newfoundland is located in an area of the continental shelf where at least two commercial, sediment-inhabiting flatfish species, viz., American plaice (Hippoglossoides platessoides) and yellowtail flounder (Limandaferruginea) are abundant and where there is a potential for release of both oil well drill-cuttings and polycyclic aromatic hydrocarbons (PAHs). The winter flounder has been used previously as a bioindicator species because of its tendency to remain buried in sediment, where hydrocarbons tend to accumulate, when not foraging for food (see Hellou et al. 1994; Payne et al. 1995). During similar studies, we compared the effect of oil well drill-cuttings and crude oil on parasitism in flounder. The rationale of using parasites is based on previous observations that some parasites respond positively or negatively following chronic exposure to toxicants depending on their concentration and, consequently, are useful as biomarkers of environmental contamination (Khan and Thulin 1991; MacKenzie 1999). Three parasites, two external and one internal, were selected because of their widespread occurrence in winter flounder inhabiting inshore localities in Newfoundland (Khan 2003). [ABSTRACT FROM AUTHOR]

Variability at six microsatellite loci was examined among 536 winter flounder Pseudopleuronectes americanus larvae collected from three locations in eastern Long Island Sound shown to be nursery areas for the species. Substantial genetic differences were seen among the putative source populations and thus appeared to be geographically based. These differences were used to characterize the most likely sources of winter flounder larvae entrained at the Millstone Power Station as well as recruitment to juvenile winter flounder collected in the Niantic River. Samples were classified to the most likely geographical source population both by a conditional maximum likelihood method and by a multi-layer feed-forward neural net trained on the differences in microsatellite allele frequencies. The classification of samples by both methods is compared and discussed in the context of winter flounder management. [ABSTRACT FROM AUTHOR]

Suppression subtractive hybridization complementary DNA libraries identified differentially ex- pressed genes in liver tissue of winter flounder collected from the highly impacted Raritan-Hudson estuary versus those from less industrialized estuaries farther south in New Jersey. Distinct transcript profiles emerged in the fish from these different habitats. A total of 251 clones from the forward (upregulated with anthropogenic impact) and reverse (downregulated with anthropogenic impact) subtracted libraries were sequenced. In the upregulated library immune response transcripts, including complement C-3, C-7, factor H, factor Bf/ C2, differentially regulated trout protein 1, and the antimicrobial hepcidin, indicated the pollution-impacted fish were under a high viral or bacterial load. Transcripts for cytochrome P450 1A, P450 3A, and glutathione S-transferase, important components of phase I and II metabolism of xenobiotics, were found in the upregulated-with-pollution library. Vitellogenins I and II and egg envelope protein (zp) appeared to be downregulated. A homologue of the tumor suppressor p33ING1 (down) and hepatocyte growth factor-like protein (up) may indicate liver damage or hepatocellular carcinoma or hepatoma. These expression patterns, confirmed by quantitative polymerase chain reaction, indicate that transcript analysis is a useful method for assessing the health of local habitats and the organisms therein. [ABSTRACT FROM AUTHOR]

Histological, biochemical and molecular techniques were used to describe the functional development of the pancreas in winter flounder (Pleuronectes americanus) with specific reference to the expression of three trypsinogen genes. The pancreas was identified shortly following hatch, appearing as a compact structure situated dorsal and slightly posterior to the liver. As the larval fish approached metamorphosis, the pancreas became diffuse, spreading throughout the mesentery surrounding the stomach, the upper intestine and the pyloric caecae. Trypsin 2 expression was detected from 5 days post-hatch (dph). Two other related trypsinogen genes isolated from the pyloric caecae (Trypsin 1) and the intestine (Trypsin 3) showed contrasting results. Trypsin 1 showed very low levels of expression and only in late larval stages and metamorphosis. Trypsin 3 showed expression only after 20 dph. In order to determine tissue-specific expression of the three trypsinogen genes, the RNA from seven gastrointestinal-associated tissues was examined. Trypsin 1 and Trypsin 2 expression was most notably associated with the pyloric caecae, cardiac stomach, pyloric stomach and the rectum, although some variation in expression level between tissues was observed. Trypsin 3 expression had a narrower tissue distribution and was only associated with the pyloric caecae and the rectum. The tissue expression patterns observed here are likely due in part to the diffuse nature of the pancreas. Trypsin-like activity was evident from hatch and continued at significant levels through to at least 25 dph. [Copyright &y& Elsevier]

Predation on the early life history of fish is an important factor regulating year-class strength. Verifying predation events, however, is difficult when analyses rely on visually identifying the remnants of partially digested fish in the stomachs of suspected predators. The objective of this study was to assess the utility of using immunological assays to detect the presence of winter flounder eggs and juveniles (Pseudopleuronectes americanus) in the gut contents of sand shrimp (Crangon septemspinosa) and green crab (Carcinus maenas). After defining assay capabilities, the stomach contents of field-collected shrimp and crabs were examined to determine if these predator–prey relationships occur under natural conditions. Winter flounder-specific antisera developed and used in this study successfully identified homologous antigens (egg or juvenile flounder extracts) without appreciably cross-reacting with antigenic material from predators or nontarget prey. Moreover, antisera detected flounder eggs 10.8–16.4 h after initial feeding by various sized shrimp, and identified juvenile flounder 9.4 and 7.8 h after initial ingestion by shrimp and crabs, respectively. Immuonological dietary analysis of decapod crustaceans collected from Niantic River, Connecticut, revealed that C. septemspinosa and C. maenas are potentially important predators on the early life stages of winter flounder. The temporal trends and magnitude of flounder predator-induced mortality was affected primarily by the spatial and temporal overlap between predator and prey (egg mortality), and the size-dependent relationships underlying crustacean and flatfish predator–prey interactions (juvenile mortality). [Copyright &y& Elsevier]

Determines the effects, geographical distribution and prevalence of the microsporan parasite Glugea stephani in winter flounder Pleuronectes americanus in Newfoundland. Influence of water temperature in parasite transmission; Size of lesions in the digestive tract; Xemonas in the submucosa; Effect of parasite on growth and mortality of the fish; Seasonal variation of infection.

The sodium dicarboxylate cotransporter located at the basolateral side supplies renal proximal tubule cells with Krebs cycle intermediates and maintains the driving force for the exchange of organic anions like PAH against α-ketoglutarate through the organic anion transporter-1. Recently, we cloned sodium dicarboxylate cotransporter-3 from winter flounder kidney (fNaDC-3). To understand the regulation of fNaDC-3, we preincubated fNaDC-3-expressing oocytes with PMA, a PKC activator. PMA dose and time dependently inhibited fNaDC-3-mediated succinate uptake. Simultaneous preincubation of fNaDC-3-expressing oocytes with 50 nM PMA and either staurosporine or RO 31-8220 for 30 min attenuated PKC-mediated inhibition of succinate uptake. Site-directed mutagenesis of the five putative PKC sites (S7, T167, S174, T188, and S396) resulted in no change in PKC-mediated inhibition of the transporter. In electrophysiological studies performed at -60 mV, the K[sub 0.5] for succinate was not significantly affected (56 ± 13 vs. 42 ± 19 µM), but Δ/[sub max] was reduced from -139 ± 49 to -20 ± 8 nA by PMA (50 nM, 30 min). Immunofluorescence analysis of fNaDC-3-expressing oocytes revealed that PMA leads to an endocytosis of fNaDC-3 protein. In conclusion, fNaDC-3 expressed in oocytes is downregulated by PMA through endocytosis. PKC consensus sites appear not to be important for this process. [ABSTRACT FROM AUTHOR]

Active transepithelial sulfate secretion rate by winter flounder renal proximal tubule epithelium in primary culture (fPTC) is dependent on intracellular carbonic anhydrase (CA) and enhanced by cortisol. To further evaluate this relationship, a partial cDNA clone (327 bp) of carbonic anhydrase II (CAII) with high sequence similarity to CAII from numerous species including fish, chicken, and human was obtained from fPTCs. The majority of CA activity and CAII protein was present in the cytosol of fPTCs; however, significant amounts of both (in addition to SDS-resistant CA activity, i.e., CAIV-like isoform) were present in concentrated plasma membranes. CAII from concentrated membranes migrated differently than purified CAII on nondenaturing PAGE gels, suggesting that CAII associates with another membrane component. Treatment of fPTCs with the cell-soluble CA inhibitor methazolamide (100 µM) caused a 58% reduction in active transepithelial SO[sup 2-, sub 4] secretion, fPTCs that were previously cultured under high-cortisol concentrations, when subjected to 5 days of low physiological levels of cortisol, had decreased CA activity (28%), CAII protein abundance (65%), and net active SO[sup 2-, sub 4] secretion (28%), with no effect on epithelial differentiation. Methazolamide and low-cortisol treatment in combination inhibited net active SO[sup 2-, sub 4] secretion 56%, which was not different than the effect of methazolamide treatment alone. These data indicate that cortisol directly increases renal CA activity, CAII protein abundance, and CA-dependent SO[sup 2-, sub 4] secretion in the marine teleost renal proximal tubule. [ABSTRACT FROM AUTHOR]

Antimicrobial peptides form one of the first lines of defense against invading pathogens by killing the microorganisms and/or mobilizing the host innate immune system. Although over 800 antimicrobial peptides have been isolated from many different species, especially insects, few have been reported from marine fish. Sequence analysis of two genomic clones (15.6 and 12.5 kb) from the winter flounder, Pseudopleuronectes americanus (Walbaum) resulted in the identification of multiple clustered genes for novel pleurocidin-like antimicrobial peptides. Four genes and three pseudogenes (Ψ) are encoded in these clusters, all of which have similar intron/exon boundaries but specify putative antimicrobial peptides differing in sequence. Pseudogenes are easily detectable but have incorrect initiator codons (ACG) and often contain a frameshift(s). Potential promoters and binding sites for transcription factors implicated in regulation of expression of immune-related genes have been identified in upstream regions by comparative genomics. Using reverse transcription-PCR assays, we have shown for the first time that each gene is expressed in a tissue-specific and developmental stage-specific manner. In addition, synthetic peptides based on the sequences of both genes and pseudogenes have been produced and tested for antimicrobial activity. These data can be used as a basis for prediction of antimicrobial peptide candidates for both human and nonhuman therapeutants from genomic sequences and will aid in understanding the evolution and transcriptional regulation of expression of these peptides. [ABSTRACT FROM AUTHOR]

Abstract Chronic stress is responsible for many problems occurring in fish holding facilities, such as increased susceptibility to disease, reduced growth rate and suppression of the immune response. The goal of this study was to verify if wild winter flounder (Pseudopleuronectes americanus Walbaum) suffer from chronic stress when kept several months in captivity. We hypothesized that winter flounder not subjected to chronic stress in captivity would have similar or higher condition indices and similar stress response compared to fish from the wild. Our results showed that the condition index of winter flounder kept in captivity was higher (1.50) than those from the wild (1.33) even after one year of captivity. The intensity of the acute stress response following short-term exposure to air was similar between wild and captive fish (no significant interaction between the factors ‘stress’ and ‘origin of the fish’). Body water content (an indicator of energy reserves) was lower (76.1%) compared to wild fish (79.8%) after one year of captivity, suggesting that the winter fast had been less energetically demanding in captive fish. These results indicate that no chronic stress was present in captive fish. On the other hand, the mortality during captivity was around 30%, which is high for the aquaculture industry. Further work to address this problem is required. [ABSTRACT FROM AUTHOR]

Abstract Three cryoprotectants (dimethyl sulphoxide, propylene glycol and glycerol) and two diluents (sucrose based and saline based) were mixed (9 parts diluent–1 part cryoprotectant) factorially to produce six extenders that were tested to develop an effective sperm cryopreservation protocol for winter flounder Pseudopleuronectes americanus (Walbaum). Sperm were diluted 1:3 with each extender and frozen by flotation on liquid nitrogen before being submerged and stored for 30 days. Sperm left unfrozen in each extender for 20 min showed no toxic effects on motility. Extenders containing propylene glycol (PG) as cryoprotectant yielded higher post-thaw sperm motilities than those containing dimethyl sulphoxide (DMSO) or glycerol. The sucrose-based diluent performed better than the saline-based diluent when DMSO was used as cryoprotectant, but there were no differences in post-thaw motility between diluents for the other cryoprotectants. Activating sperm with ovarian fluid and sea water instead of sea water alone had no effect on post-thaw motility. In fertilization trials, no differences were observed between any of the extenders and fresh milt when milt, eggs and sea water were left in contact for 1 h. When sperm were forced to compete for eggs by reducing contact time to 20 s, fertilization results followed those of sperm motility rates. Percentage hatch and morphology of larvae at hatching did not differ for eggs fertilized by cryopreserved and fresh sperm. This study represents the first reported successful attempt at cryopreserving winter flounder sperm and should improve gamete and broodstock management protocols for this species. [ABSTRACT FROM AUTHOR]

Antimicrobial peptides play a crucial role as the first line of defense against invading pathogens. Several types of antimicrobial peptides have been isolated from fish, mostly of the cationic α-helical variety. Here, we present the cDNA sequences of five highly disulphide-bonded hepcidin-like peptides from winter flounder, Pseudopleuronectes americanus (Walbaum) and two from Atlantic salmon, Salmo salar (L.). These hepcidin-like molecules consist of a 24 amino acid signal peptide and an acidic propiece of 38–40 amino acids in addition to the mature processed peptide of 19–27 amino acids. Exhaustive data mining of GenBank with these sequences revealed that similar peptides are encoded in the genomes of Japanese flounder, rainbow trout, hybrid striped bass and medaka, indicating that they are widespread among fish. Southern hybridization analysis suggests that closely related hepcidin-like genes are present in other flatfish species, and that they exist as a multigene family clustered on the winter flounder genome. Hepcidin variants are differentially expressed during bacterial challenge, during larval development of P. americanus and in different tissues of adult fish. [Copyright &y& Elsevier]

Abstract Like most small marine fish larvae, the stomachs of winter flounder Pseudopleuronectes americanus are undeveloped at first feeding and have relatively reduced digestive capacity. This work was undertaken to test whether larvae at the onset of stomach differentiation (larval size about 5.5 mm) could be early weaned onto a commercial microencapsulated diet. We assessed the effect of early weaning by first comparing growth performance (standard length, total protein content and age at metamorphosis) of larvae fed enriched live prey from first feeding to a size of 5.5 mm and then reared on three different feeding regimes until metamorphosis: (1) live prey (LP) as a control group; (2) mixed feeding of live prey and microencapsulated diet (LP-ME); (3) exclusively microencapsulated diet (ME) after fast weaning over 4 days (to a larval size of 6.2 mm). No differences were observed between larval development in the two first groups, which began metamorphosis at 40 days old. The larvae of the third group showed significantly slower growth that resulted in a delay of 4 days in the onset of metamorphosis. Differences in live prey availability between the treatments and the short transition period to allow the larvae to adapt to the new diet were identified as possible contributing factors to the slower growth and to the delay in metamorphosis of early weaned larvae. In a second experiment, the transitional weaning period was increased until the larvae were 6.6 mm in length. Weaning at that size resulted in no slowing of growth or delay in metamorphosis, suggesting that the feeding schedule was adequate. [ABSTRACT FROM AUTHOR]

Winter flounder show good potential for culture in Atlantic Canada. Information about their nutritional requirements is necessary in order to be able to formulate cost-effective feeds that produce acceptable growth rates. Fish meal, the principal protein source in most fish feeds, is one of the more expensive ingredients. Reduction of the amount of protein in diets would reduce the cost of feed. Therefore, a 10-week feeding trial was conducted with juvenile winter flounder (initial weight 0.8 g) in order to determine the effect of reducing digestible protein-to-energy levels in diets on specific growth rates (SGR), feed efficiency (FE) and respiration rates. Experimental diets were formulated to contain dietary protein-to-lipid levels of 50:10%, 45:15% and 40:20%. There were significant differences in final weights and percent weight gain among all three dietary treatments. Winter flounder fed the 50:10 diet (26.6 mg kJ−1 digestible protein to energy) had the highest specific growth rate (2.1±0.2% weight day−1), which was significantly greater (P<0.05) than those receiving the 40:20 diet, 20.9 mg kJ−1 (1.1±0.3% day−1), but not significantly different from those that fed the 45:15, 23.5 mg kJ−1 diet (1.7%). The 50:10 diet-fed fish had a feed efficiency ratio (0.7±0.1) which was significantly better than the 40:20 group (0.2±0.1, P<0.05), but not significantly different from the 45:15 diet-fed fish (0.5±0.1). While not significantly different (P=0.06), the protein efficiency of the 50:10 diet-fed fish tended to be higher than the other two groups. [Copyright &y& Elsevier]

Pleurocidin is an antimicrobial peptide isolated from winter flounder and has been previously localized to mucous cells of the skin epidermis and the intestine. The present study was designed to determine the cell type involved in pleurocidin gene expression and protein synthesis in gills from the same species. Whole-mount in situ hybridization with a pleurocidin-specific RNA probe and whole-mount immunohistochemistry with an anti-pleurocidin antibody localized the expression of this gene and the synthesis of its corresponding protein in a population of cells primarily isolated to the non-lamellar portion of the gill filament. Histological techniques allowed the presumptive identification of these cells as eosinophilic granular cells. These observations suggest that pleurocidin is expressed in not one but two distinct populations of cells within the winter flounder, one being an important group of inflammatory cells, the eosinophilic granular cells. [ABSTRACT FROM AUTHOR]

Abstract Viable interspecific hybrids between yellowtail flounder (Pleuronectes ferrugineus , Storer) and winter flounder (Pleuronectes americanus , Walbaum) were produced by artificial insemination of yellowtail flounder eggs with winter flounder sperm. However, mean fertilization rate, hatching success and early survival up to 3 weeks post hatch were significantly lower than those of parental pure cross controls (P < 0.01). Overall, cytogenetic traits (karyological analysis and estimation of cellular DNA contents using flow cytometry) of hybrid flounder were intermediate between the two parental species. Microsatellite assay was used to distinguish the parental genomes in the hybrids; in most cases, one allele was specific to each of the parents. Morphometrics assessed by body proportions indicated that hybrids generally displayed a morphology intermediate between the maternal and paternal species. Interspecific hybrids exhibited abnormal and retarded gonad development in both sexes based on histological analysis of gonads from adult fish. The sterility of the hybrids presents a significant advantage for their use in aquaculture, as potential escapees would not be capable of reproducing in the wild and contaminating natural stocks. [ABSTRACT FROM AUTHOR]

The partial sequencing of two lipases from winter flounder Pseudopleuronectes americanus , one most closely related to gastric, lingual and lysosomal acid lipase from other vertebrates and one most closely related to bile salt-activated lipase, is reported. Biochemical analyses of enzymatic activity demonstrated the greater contribution made by bile salt-activated lipase relative to neutral bile salt-independent lipase. Using molecular techniques, the tissue-specific expression of bile salt-activated lipase in pancreatic tissue and acid triacylglycerol lipase in a wide variety of organs was demonstrated. Furthermore, the developmental expression of these types of lipase in larval fish was established. [ABSTRACT FROM AUTHOR]

Examines the contributions of the N- and C-terminal sequences to the antifreeze activity of liver- and skin-type antifreeze proteins (AFTs). Synthesis of polypeptides where the N- and C-terminal sequences of two representative AFPs, wflAFP-6 and wfsAFP; Systematic exchange and assaying for antifreeze activity and α-helical content; Antifreeze proteins from winter flounder.

SO[sup 2-, sub 4] transport by winter flounder intestine in Ussing chambers was characterized. With 50 mM SO[sup 2-, sub 4] (physiological level) bathing the lumen, net absorption (lumen to blood) dominated. Under shortcircuited conditions, 1 mM SO[sup 2-, sub 4] on both sides, net active SO[sup 2-, sub 4] secretion occurred (8.55 ± 0.96 nmol·cm[sup -2]·h[sup -1]). NaCN (10 nM), ouabain (10[sup -4] M), and luminal DIDS (0.2 mM) inhibited net secretion. Removal of luminal Cl[sup -] and HCO[sup -, sub 3] together (Cl[sup -]-HCO[sup -, sub 3]) or Cl[sup -] alone blocked net secretion, whereas removal of luminal HCO[sup -, sub 3] alone increased net secretion. SO[sup 2-, sub 4] uptake into foregut brush-border membrane vesicles was stimulated by a trans-Cl[sup -] gradient (in > out) and unaffected by a trans-HCO[sup -, sub 3] gradient (in > out). Shortcircuiting with K[sup +] (in = out) and valinomycin had no effect on Cl[sup -]-stimulated SO[sup 2-, sub 4] uptake, suggesting electroneutral exchange. Satiety (i.e., full stomach) stimulated the unidirectional absorptive flux, eliminating net secretion. It was concluded that the intestine is a site of S0[sup 2-, sub 4] absorption in marine teleosts and that active S0[sup 2-, sub 4] secretion is in exchange for luminal Cl[sub -]. [ABSTRACT FROM AUTHOR]

Swimming behaviour of winter flounder (Pleuronectes americanus) was recorded near baited hooks on natural fishing grounds using an underwater video camera. Winter flounder were observed to stay on or very close to the seabed, never rising to more than 0.6 m off bottom during 1 month of observation. Winter flounder were recorded to take bait actively at temperatures as low as −1.2 °C. Movement of winter flounder was characterised by a period of swimming off seabed followed by a period of resting on the seabed. The proportion of time swimming off seabed as opposed to resting on the seabed was positively related to water temperature. Flounder spent an average of 32% of time in swimming when at −1.2 °C compared with 67% when at 4.4 °C. Voluntary swimming speed of the flounder during the period of swimming was lower at lower temperatures. An average swimming speed of 0.52 body lengths per second (L s−1) at −1.2 °C was recorded compared with 0.95 L s−1 at 4.4 °C. Overall rate of movement was reduced by three-fold when water temperature fell from 4.4 to −1.2 °C. The reduced rate of movement at lower temperatures is discussed in relation to potential fishing area of fixed fishing gears such as gillnets. [Copyright &y& Elsevier]

The article cites a study conducted to ascertain the effect of the effluent on a number of biological variables including gonadal development in male winter flounder in the latter part of summer when induction occurs. It compared variables between samples collected near two mills and five reference sites. Significant differences in selected biological variables were observed in male winter flounder sampled near the two pulp and paper mills when compared to the reference sites. Macroscopic observations revealed that the percentage of skin lesions, consisting of fin necrosis and/or epidermal ulcers, metacercariae of Cryptocotyle lingua encapsulated in the epidermis and discoloration in the liver were significantly greater in fish sampled near the two mills at Birchy PulpCove and Port Harmon than at the reference locations.

In order to establish effective procedures for chromosome manipulations in the winter flounder Pseudopleuronectes americanus, temperature-dependent measures of mitotic intervals (τ0) were determined. Mitotic intervals (τ0) were determined by averaging the duration of the first and third embryonic divisions over a range of temperatures from 0 to 20 °C. At higher temperatures, eggs developed faster and underwent more identical development. Mitotic intervals for winter flounder were 98.5±1.3 min at 0 °C, 79.5±1.7 min at 5 °C, 59.5±1.7 min at 10 °C, 38.7±1.8 min at 15 °C and 23.9±2.2 min at 20 °C. There were strong, negative correlations between mitotic interval and water temperature for all five temperatures application (Y=−19.00X+117.40, R2=0.9969, where Y is mitotic interval and X is temperature). [Copyright &y& Elsevier]

Reports changes in estuarine ecosystems as of May 1, 2002. Effect of climate warming on the distribution of winter flounder in Narragansett Bay; Global spread of microorganisms by ship; Striped bass predation on Chesapeake Bay crabs; Adaptive rehabilitation of estuarine ecosystems.