Winter Flounder Research Articles

Linear antimicrobial peptides with activity against herpes simplex virus 1 and Aichi virus.

Viruses are the major cause of disease and mortality worldwide. Nowadays there are treatments based on antivirals or prophylaxis with vaccines. However, the rising number of reports of viral resistance to current antivirals and the emergence of new types of virus has concerned the scientific community. In this scenario, the search for alternative treatments has led scientists to the discovery of antimicrobial peptides (AMPs) derived from many different sources. Since some of them have shown antiviral activities, here we challenged 10 synthetic peptides from different animal and plant sources against, herpes simplex virus 1 (HSV-1), and Aichi virus. Among them, the highlight was Pa-MAP from the polar fish Pleuronectes americanus, which caused around 90% of inhibition of the HSV with a selectivity index of 5 and a virucidal mechanism of action. Moreover, LL-37 from human neutrophils showed 96% of inhibition against the Aichi virus, showing a selectivity index of 3.4. The other evaluated peptides did not show significant antiviral activity. In conclusion, the present study demonstrated that Pa-MAP seems to be a reliable candidate for a possible alternative drug to treat HSV-1 infections. © 2016 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 108: 1-6, 2017.

Trends in nitrogen isotope ratios of juvenile winter flounder reflect changing nitrogen inputs to Rhode Island, USA estuarine systems

Nitrogen isotope ratios (δ15N) in juvenile winter flounder, Pseudopleuronectes americanus, were used to examine changes in nitrogen inputs to several Rhode Island, USA estuarine systems. Fish were collected over two three-year periods with a ten-year interval between sampling periods (2002–2004 and 2012–2014). During that interval numerous changes to nutrient management practices were initiated in the watersheds of these estuarine systems including the upgrade of several major wastewater treatment facilities that discharge to Narragansett Bay, which significantly reduced nitrogen inputs. Following these reductions, the δ15N values of flounder in several of the systems decreased as expected; however, isotope ratios in fish from upper Narragansett Bay significantly increased. We believe that low δ15N values measured in 2002–2004 were related to concentration-dependent fractionation at this location. Increased δ15N values measured between 2012 and 2014 may indicate reduced fractionation or that changes in wastewater treatment processes altered the nitrogen isotopic ratios of the effluents.

Feeding habits and dietary overlap of age-0 winter flounder (Pseudopleuronectes americanus) and summer flounder (Paralichthys dentatus) in southern New England tidal rivers

Feeding habits and dietary overlap of age-0 winter flounder (Pseudopleuronectes americanus) and summer flounder (Paralichthys dentatus) in southern New England tidal rivers

Antifreeze Mechanism Study of Ice Growth Inhibition by Spin Labeled Ice Binding Proteins

Ice binding proteins (IBPs) were found to play critical role for various organisms to survive in extreme cold climates. We carried out the study on spin labeled type 1 IBPs whose sequence is from that of the Pseudopleuronectes americanus (winter flounder). The spin labeled sites involved in our study have undergone a manipulation on different directions along the α-helical structure. Site directed spin labeling technique was used to make the spin labeled peptides. Combination of the EPR spectra at low temperatures and observation of their inhibition to the growth of ice crystals gives us insight into their antifreeze mechanism on both molecular scale and microscopic scale. This poster will focus on presenting the experimental result of ice crystal inhibition, while another poster of my fellow student researchers will focus on the EPR result. Osmometer-microscopy technique was used to observe the ice crystals. The changes in antifreeze activities, kinetics of ice crystals’ growths and shapes of the ice crystals by these spin labeled IBPs compared with the wild type IBP were observed and will be discussed in this poster. Results include observations of IBP binding on both sides of the basal plane and prism faces of ice seed crystals. Significant differences between thermal hysteresis and crystal structured due to the binding of the Spin labeled IBPs were observed which is correlated to the EPR spectra at molecular level. Single cystal growth on the horizontal axis is observed within the hysteresis gap of the spin labeled IBPs while the wild type IBP showed no crystal growth during the hysteresis gap. There were various differences between thermal hysteresis values between the different spin labeled IBPs.

Indications of Offshore Spawning by Southern Gulf of Maine Winter Flounder

AbstractThis is the first study to document quantitatively that Gulf of Maine (GOM) Winter Flounder Pseudopleuronectes americanus spawn offshore. Three sites (southern Jeffreys Ledge, Bigear [an area southwest of Tillies Bank], and a portion of Stellwagen Bank National Marine Sanctuary) were sampled during spring 2016 to determine whether Winter Flounder are spawning in non‐coastal, deep waters in the southern GOM. In total, 1,384 Winter Flounder were caught by trawl, measured, sexed, and assessed for reproductive stage during the peak spawning season (March–May). These fish showed clear signs that spawning was occurring either at or very near to all three sites surveyed. In all sites, a shift from prespawn to postspawn females occurred. Running ripe females were caught at both Jeffreys Ledge and Stellwagen Bank on multiple occasions, and ripe and recently spawned females were caught at Bigear. Given that these sites are over 15 km from the coast, it is not energetically likely that fish in such advanced reproductive condition are migrating to shore to spawn. Essential fish habitat (EFH) for GOM Winter Flounder is categorized as waters with depths of 5 m or less. The present study clearly shows that this depth range is incomplete and thus inaccurate for southern GOM Winter Flounder. Although it is irrefutable that GOM estuaries and shallow bays are important as nursery grounds for juvenile Winter Flounder and as postspawn feeding grounds for adults, the current GOM EFH designation warrants reclassification.

Modeling of paired zero-inflated continuous data without breaking down paired designs

ABSTRACTPaired data have been widely collected in the efficiency studies of a new method against an established method in environmental, ecological and medical studies. For example, in comparative fishing studies, ability of catching target species (fish catch) or reducing the catch of non-target species (fish bycatch) is usually investigated through a paired design. These paired fish catches by weight are generally skewed and continuous, but with a significant portion of exact zeros (no catch). Such zero-inflated continuous data are traditionally handled by two-part models where the zero and positive components are handled separately; however, this separation generally destroys paired structure, and thus may result in substantial difficulty in characterizing the relative efficiency between two methods. To overcome this problem, we consider compound Poisson mixed model for paired data with which the zero and non-zero components are characterized in an integral way. In our approach, the clustering effects by pair are captured by incorporating relevant random effects. Our model is estimated using orthodox best linear unbiased predictor approach. Unlike two-part models, our approach unifies inferences of zero and positive components. Our method is illustrated with analyses of winter flounder bycatch data and ultrasound safety data.

Habitat Use in a Depleted Population of Winter Flounder: Insights into Impediments to Population Recovery

AbstractThe distribution and demographics of a population of Winter Flounder Pseudopleuronectes americanus were examined for changes related to habitat quality over a fishery‐independent survey period of 29 years, encompassing an 82% decline in abundance. We tested for spatial and temporal variation in indicators of fitness to determine whether they revealed likely processes that resulted in the observed patterns of habitat use. We also assessed temporal changes in fitness and inferred changes in habitat quality associated with population decline. We focused on the condition of postspawn (resting) mature and immature fish of both sexes during a critical period of spring feeding prior to summer migration. Analysis of variance of individual condition indices (log10[length]–log10[weight] regression residuals) by sex/maturity group and time period identified consistent and significant differences among six survey strata. Highest condition indices were observed for fish that were captured in shallow (<18‐m) mud, sand, and transitional bottom sediment and deep (>18‐m) mud areas, collectively classified as high‐quality habitat. The proportion of the population that occupied high‐quality habitat remained unchanged at approximately 60% over the time series. As abundance decreased, condition decreased in mature females, increased in immature fish of both sexes, and was mixed in mature males. Additionally, the proportion mature at length shifted significantly upward for both sexes, the back‐calculated lengths at ages 2 and 3 increased for mature individuals, and the estimated winter growth declined for age‐3 mature and immature females. The results suggested increased competition for prey among mature fish and increased predation pressure on smaller fish. This Winter Flounder population may be responding to an increase in the abundance of competing mid‐Atlantic species, which was brought about by increasing water temperature. These second‐order effects may have chronically hindered Winter Flounder reproduction and therefore stock rebuilding, especially in areas of low‐quality habitat.Received September 23, 2015; accepted July 18, 2016 Published online September 30, 2016

Effects of preheating on ice growth in antifreeze polypeptides solutions in a narrow space

We conducted measurements on the unidirectional freezing of aqueous solutions of polypeptide or of winter flounder antifreeze protein. The polypeptide was based on a part of the antifreeze protein. We measured temperatures in the solutions and ice with a small thermocouple, and defined the interface temperature as the temperature at the tip of the serrated or pectinate interface. It was found that the interface temperature of these solutions was lower than that of pure water. To vary the activity of these solutes, we preheated the solutions and cooled them before conducting the measurements. We found that preheating for several hours caused further decreases in the interface temperature and a decrease in the interface velocity. In addition, the inclined interfaces became wider as a result of the preheating. Thus, the supercooled states in the solutions were enhanced by the preheating. To investigate the reasons for these changes, we measured the aggregates of the solutes in the solutions. These aggregates became larger as a result of preheating. It can therefore be concluded that these large aggregates attenuated the ice growth by their interaction with the ice surfaces.

Effects of climate change on four New England groundfish species

Multiple groundfish stocks in New England remain depleted despite management measures that have been effective elsewhere. A growing body of research suggests that environmental change driven by increasing concentrations of carbon dioxide in the atmosphere and ocean is unfolding more rapidly in New England than elsewhere, and is an important factor in the failure of these stocks to respond to management. We reviewed research on effects of changes in temperature, salinity, dissolved oxygen, pH, and ocean currents on pelagic life stages, post-settlement life stages, and reproduction of four species in the New England groundfish fishery: Atlantic cod (Gadus morhua), haddock (Melanogrammus aeglefinus), winter flounder (Pseudopleuronectes americanus), and yellowtail flounder (Limanda ferruginea). The volume of research on cod was nearly equal to that on the other three species combined. Similarly, many more studies examined effects of temperature than other factors. The majority of studies suggest adverse outcomes, with less evidence for mixed or positive effects. However, for all of the factors other than temperature, there are more knowledge gaps than known effects. Importantly, most work to date examines impacts in isolation, but effects might combine in nonlinear ways and cause stronger reductions in stock productivity than expected. Management strategies will need to account for known effects, nonlinear interactions, and uncertainties if fisheries in New England are to adapt to environmental change.

Ice Growth Inhibition in Antifreeze Polypeptide Solution by Short-Time Solution Preheating.

The objective of this study is to enhance the inhibition of ice growth in the aqueous solution of a polypeptide, which is inspired by winter flounder antifreeze protein. We carried out measurements on unidirectional freezing of the polypeptide solution. The thickness of the solution was 0.02 mm, and the concentration of polypeptide was varied from 0 to 2 mg/mL. We captured successive microscopic images of ice/solution interfaces, and measured the interface velocity from the locations of tips of the pectinate interface in the images. We also simultaneously measured the temperature by using a small thermocouple. The ice/solution interface temperature was defined by the temperature at the tips. It was found that the interface temperature was decreased with an increasing concentration of polypeptide. To try varying the activity of the polypeptide, we preheated the polypeptide solution and cooled it before carrying out the measurements. Preheating for 1–5 hours was found to cause a further decrease in the interface temperature. Furthermore, wider regions of solution and ice with inclined interfaces in the pectinate interface structure were observed, compared with the case where the solution was not preheated. Thus, the ice growth inhibition was enhanced by this preheating. To investigate the reason for this enhancement, we measured the conformation and aggregates of polypeptide in the solution. We also measured the local concentration of polypeptide. It was found that the polypeptide aggregates became larger as a result of preheating, although the polypeptide conformation was unchanged. These large aggregates caused both adsorption to the interface and the wide regions of supercooled solution in the pectinate interface structure.

Juvenile winter flounder (Pseudopleuronectes americanus) and summer flounder (Paralichthys dentatus) utilization of Southern New England nurseries: Comparisons among estuarine, tidal river, and coastal lagoon shallow-water habitats.

This study evaluated the relative importance of the N arragansett Bay estuary (RI and MA, USA), and associated tidal rivers and coastal lagoons, as nurseries for juvenile winter flounder, Pseudopleuronectes americanus, and summer flounder, Paralichthys dentatus. Winter flounder (WF) and summer flounder (SF) abundance and growth were measured from May to October (2009-2013) and served as indicators for the use and quality of shallow-water habitats (water depth < 1.5-3.0 m). These bioindicators were then analyzed with respect to physiochemical conditions to determine the mechanisms underlying intra-specific habitat selection. WF and SF abundances were greatest in late May and June (maximum monthly mean = 4.9 and 0.55 flounder/m2 for WF and SF, respectively), and were significantly higher in the tidal rivers relative to the bay and lagoons. Habitat-related patterns in WF and SF abundance were primarily governed by their preferences for oligohaline (0.1-5 ppt) and mesohaline (6-18 ppt) waters, but also their respective avoidance of hypoxic conditions (< 4 mg DO/L) and warm water temperatures (> 25 °C). Flounder habitat usage was also positively related to sediment organic content, which may be due to these substrates having sufficiently high prey densities. WF growth rates (mean = 0.25 ± 0.14 mm/d) were negatively correlated with the abundance of conspecifics, whereas SF growth (mean = 1.39 ± 0.46 mm/d) was positively related to temperature and salinity. Also, contrary to expectations, flounder occupied habitats that offered no ostensible advantage in intra-specific growth rates. WF and SF exposed to low salinities in certain rivers likely experienced increased osmoregulatory costs, thereby reducing energy for somatic growth. Low-salinity habitats, however, may benefit flounder by providing refugia from predation or reduced competition with other estuarine fishes and macro-invertebrates. Examining WF and SF abundance and growth across each species' broader geographic distribution revealed that southern New England habitats may constitute functionally significant nurseries. These results also indicated that juvenile SF have a geographic range extending further north than previously recognized.

First Observation of YOYParalichthys dentatus(Summer Flounder) in a Southern Maine Estuary

Abstract Herein we present evidence of the first observation of YOY Paralichthys dentatus (Summer Flounder) in the Saco River estuary, ME, in June of 2012. A possible explanation for the occurrence of YOY summer flounder in this region could be range expansion, which may have destructive effects on southern Maine estuary systems. As active predators, Summer Flounder have the potential to exploit locally abundant fishes, including Pseudopleuronectes americanus (Winter Flounder) and Ammodytes americanus (American Sand Lance).

A polyalanine peptide derived from polar fish with anti-infectious activities.

Due to the growing concern about antibiotic-resistant microbial infections, increasing support has been given to new drug discovery programs. A promising alternative to counter bacterial infections includes the antimicrobial peptides (AMPs), which have emerged as model molecules for rational design strategies. Here we focused on the study of Pa-MAP 1.9, a rationally designed AMP derived from the polar fish Pleuronectes americanus. Pa-MAP 1.9 was active against Gram-negative planktonic bacteria and biofilms, without being cytotoxic to mammalian cells. By using AFM, leakage assays, CD spectroscopy and in silico tools, we found that Pa-MAP 1.9 may be acting both on intracellular targets and on the bacterial surface, also being more efficient at interacting with anionic LUVs mimicking Gram-negative bacterial surface, where this peptide adopts α-helical conformations, than cholesterol-enriched LUVs mimicking mammalian cells. Thus, as bacteria present varied physiological features that favor antibiotic-resistance, Pa-MAP 1.9 could be a promising candidate in the development of tools against infections caused by pathogenic bacteria.

Structure and Dynamics of Antifreeze Protein–Model Membrane Interactions: A Combined Spectroscopic and Molecular Dynamics Study

Antifreeze proteins (AFPs) are the key biomolecules that enable species to survive under subzero temperature conditions. The physiologically relevant activities of AFPs are based on the adsorption to ice crystals, followed by the inhibition of subsequent crystal layer growth of ice, routed with depression in freezing point in a noncolligative manner. The functional attributes governing the mechanism by which AFPs inhibit freezing of body fluids in bacteria, fungi, plants, and fishes are mainly attributed to their adsorption onto the surface of ice within the physiological system. Importantly, AFPs are also known for their application in cryopreservation of biological samples that might be related to membrane interaction. To date, there is a paucity of information detailing the interaction of AFPs with membrane structures. Here, we focus on elucidating the biophysical properties of the interactions between AFPs and micelle models that mimic the membrane system. Micelle model systems of zwitterionic DPC and negatively charged SDS were utilized in this study, against which a significant interaction is experienced by two AFP molecules, namely, Peptide 1m and wfAFP (the popular AFP sourced from winter flounder). Using low- and high-resolution biophysical characterization techniques, such as circular dichroism (CD) and NMR spectroscopy, a strong evidence for the interactions of these AFPs with the membrane models is revealed in detail and is corroborated by in-depth residue-specific information derived from molecular dynamics simulation. Altogether, these results not only strengthen the fact that AFPs interact actively with membrane systems, but also demonstrate that membrane-associated AFPs are dynamic and capable of adopting a number of conformations rendering fluidity to the system.

Pa-MAP 1.5 and 1.9: Mechanisms of Action of two Antimicrobial Peptides

Increased resistance to conventional antibiotics has become a major problem worldwide. Existing antibiotics are increasingly ineffective, as a result of resistance, becoming imperative to find new antibacterial strategies. One of the most promising possibilities is the use of antimicrobial peptides (AMPs), which play an important role in the innate immune response of different organisms. Some of these peptides can also act against cancer cells (anticancer peptides, ACPs). AMPs are small cationic amphipathic molecules. Their mechanisms of action are not fully understood, but their physicochemical properties are determinant, namely their amphipathic conformation upon interaction with biomembranes and their positive net charge, which allows them to interact preferentially with negatively charged biomembranes, like those of Gram-negative bacteria. Until now, AMPs demonstrate a low propensity for drug resistance development.Two different AMPs (Pa-MAP 1.5 and 1.9) were synthetically created based on an antifreezing peptide from the Antarctic fish Pleuronectes americanus. Both peptides showed promising therapeutic results against bacteria and cancer cells. Membrane leakage tests using lipid vesicles to mimic bacteria and cancer cells have shown that these two AMPs efficiently induce membrane disruption. Dynamic light scattering, surface plasmon resonance and zeta-potential studies confirmed the interaction of the peptides with the membranes. Studies using fluorescent probes that report different aspects of peptide-membrane interaction (DPH, TMA-DPH, di-8-ANEPPS and Laurdan) were also conducted, either using model vesicles or with Escherichia coli. Atomic force microscopy imaging of the AMPs effects on live cells and flow cytometry measurements confirmed the results obtained with lipid vesicles. The results obtained show that, although these two AMPs have several similarities, they act through different mechanisms of action.

M1008 冬ガレイ由来不凍タンパク質の一部を基にしたポリペプチドの氷成長抑制に関する分子動力学解析(GS6 熱工学(2),修士研究発表セッション)

M1008 冬ガレイ由来不凍タンパク質の一部を基にしたポリペプチドの氷成長抑制に関する分子動力学解析(GS6 熱工学(2),修士研究発表セッション)

分子動力学解析を用いた冬ガレイ由来不凍タンパク質とイオンが有する水分子の運動抑制効果の調査

We have carried out molecular dynamics analysis for water with an ice wall, winter flounder antifreeze protein and ions to understand mechanism of a ‘synergistic effect’. This effect shows the freezing point of mixed solution is lower than the sum of the freezing point of antifreeze protein solution and the freezing point of salt solution. It is found that movement of water molecules is more inhibited by the interaction of antifreeze protein and ions than the movement of water moleculars in each single-solute solution. This may be due to the fact that the antifreeze protein strengthens hydration shell around sodium ions.

二種類のポリペプチド水溶液の氷表面温度と円偏光二色性の計測

We conducted measurements on unidirectional freezing and circular dichroism for preheated solution and unheated solution of a polypeptide based on winter flounder antifreeze protein. The interface temperature were measured with a thermocouple. The secondary structure of this polypeptide was measured with circular dichroism spectrophotometer. It was found from the circular dichroism spectra that the polypeptide had a β-sheet structure. Although the interface temperature for the unheated solution of the polypeptide did not drop, the interface temperature for the preheated solution showed significant dropped.

Carbon and nitrogen isotope ratios of juvenile winter flounder as indicators of inputs to estuarine systems

Stable carbon and nitrogen isotope ratios were measured in young-of-the-year (YOY) winter flounder, Pseudopleuronectes americanus, collected from several Rhode Island, USA estuarine systems. These included three coastal lagoons, an estuarine river and Narragansett Bay. The δ13C trends observed along transects in several systems showed isotopically depleted terrestrial signals in the upper reaches of the estuaries. Significant differences (P<0.05) in δ15N were observed among all estuarine systems and these differences correlated (P<0.01) with human population densities in the watersheds. Although Narragansett Bay has a strong north–south gradient in nutrient concentrations this trend was not reflected in flounder δ15N. The northernmost station with the highest nutrient concentrations unexpectedly had significantly lower δ15N values. Depleted δ15N values at this nutrient-rich station may indicate that concentration-dependent fractionation needs to be considered when using nitrogen isotope ratios in biota to monitor anthropogenic nitrogen inputs in systems with high nitrogen loadings.

Life on the bottom: the chemical and morphological asymmetry of winter flounder (Pseudopleuronectes americanus) sagittae

We observed that paired winter flounder (Pseudopleuronectes americanus) sagittae are not morphologically or chemically identical. Statistically significant (p < 0.05) chemical asymmetry was detected between the sagittae in five of eight elements (with three other elements, Sr, I, and Sn not statistically different). The blind-side otolith exhibited higher mean concentrations of Ba, Mn, Mg, Cu, and Zn trace elements than the eyed-side otolith. These asymmetries may be due to blind-side otoliths absorbing higher concentrations of transitional elements, partly as a result of environmental heterogeneity caused by redox reactions emanating from the sediments. Metamorphic transformation and the subsequent shift to the benthos by fully formed fish may also account for element concentration levels that were significantly different between juveniles and both sub-adults and adults. Our results also suggest that chemical uptake in a pair of winter flounder sagittae is an asynchronous event, and that each otolith potentially records the chemical history of its environment independent of the other. The physiological pathway for entry into winter flounder otoliths is uncertain and warrants further testing. Overall, our results have implications for other flatfish genera as well, and demonstrate the need for standardization of methodology when conducting otolith chemistry on flatfishes.