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Articles 1 - 9 of 9
Full-Text Articles in Life Sciences
Uptake Of Dissolved Free Amino Acids By Northern Quahogs, Mercenaria Mercenaria, And Its Relative Importance To Organic Nitrogen Deposition In Narragansett Bay, Rhode Island, Michael A. Rice
Michael A Rice
Studies were undertaken to determine the relationship between size of northern quahogs Mercenaria mercenaria and the rate at which they transport aspartic acid. Quahogs ranging from 25 to 103 mm valve length were collected in Narragansett Bay and placed in seawater aquaria (27 ppt, 20 deg C) and allowed to pump actively. Uptake experiments were carried out using 1 umol/L C(14) radiolabeled aspartic acid. Aspartate transport rates in umol/h can be related to valve length by the allometric equation with a = 24.32 and b = 0.905 when valve length is in mm. In May 1990, near bottom samples of …
Food-Limited Growth And Condition Index In The Eastern Oyster, Crassostrea Virginica (Gmelin, 1791), And The Bay Scallop, Argopecten Irradians Irradians (Lamarck, 1819), Michael A. Rice, Robert B. Rheault Jr.
Food-Limited Growth And Condition Index In The Eastern Oyster, Crassostrea Virginica (Gmelin, 1791), And The Bay Scallop, Argopecten Irradians Irradians (Lamarck, 1819), Michael A. Rice, Robert B. Rheault Jr.
Michael A Rice
The growth response of the eastern oyster, Crassostrea virginica, and the bay scallop, Argopecten irradians irradians, to varying degrees of food limitation was evaluated. Under conditions of low current speed, dense assemblages of shellfish can rapidly deplete ambient food concentrations, resulting in measurable effects on growth and condition index. A flume study demonstrated significant growth and condition index responses to resource competition after reductions as small as 27% in relatively high ambient food concentrations (—4.6 u.g/1 chlorophyll). Growth rates and condition index are linearly correlated with the average chlorophyll ration consumed. A field study demonstrated similar growth responses when the …
Experimental Culture And Particle Filtration By Asian Moon Scallops, Amusium Pleuronectes, Michael A. Rice, Robert B. Rheault, Miguel S. Perez, Vicente S. Perez
Experimental Culture And Particle Filtration By Asian Moon Scallops, Amusium Pleuronectes, Michael A. Rice, Robert B. Rheault, Miguel S. Perez, Vicente S. Perez
Michael A Rice
Growth rates were determined for scallops (35-75 mm valve height) held in pocket nets and lantern nets at varying densities. The Ford-Walford linear transformation of the von Bertalanffy growth equation was used to allow quantification of food-limited stunting. Pocket nets allowed for greater growth of scallops than did the lantern nets at all stocking densities. The growth rates of scallops in pocket nets, nevertheless, were well below the growth of scallops in the wild. Clearance rates of Caribbean strains of Isochrysis galbana (C-ISO) and Chaetocerous gracilus (C-Cg) were determined for moon scallops. Amusin pleuronectes, in static chambers at 28ºC. The …
The Effects Of Copper, Cadmium And Zinc On Particle Filtration And Uptake Of Glycine In The Pacific Oyster Crassostrea Gigas, Wenyu Lin, Michael A. Rice, Paul K. Chien
The Effects Of Copper, Cadmium And Zinc On Particle Filtration And Uptake Of Glycine In The Pacific Oyster Crassostrea Gigas, Wenyu Lin, Michael A. Rice, Paul K. Chien
Michael A Rice
1. The filtration rate (volume of water completely cleared of collodial carbon per unit time) by control oysters is 36.60 ml/g hr ± 7.68 (sd).2. Filtration rates decrease with increasing concentrations of Cd2+ and Zn2+.3. In 8–16 mg/l Cu2+, filtration rates are significantly higher than the control, but in Cu2+ concentrations above 32 mg/l, filtration rates are lower than controls.4. Influx of 14C-glycine is characterized by Michaelis-Menten kinetics with Jmax and Kt values of 1.85 ± 0.097 μmol/g hr and 33.7 ± 4.6 μM respectively.5. The uptake rate of glycine from 1 μM solution is 37.79 μmol/g hr.6. In order …
Influx, Net Flux And Transepithelial Flux Of Amino Acids In The Hardshell Clam Mercenaria Mercenaria (Linne): Influence Of Salinity, Michael Rice, Grover Stephens
Influx, Net Flux And Transepithelial Flux Of Amino Acids In The Hardshell Clam Mercenaria Mercenaria (Linne): Influence Of Salinity, Michael Rice, Grover Stephens
Michael A Rice
1.1. The effects of salinity on the uptake and internal distribution of alanine and other free amino acids (FAA) in hardsell clams, Mercenaria, was studied by radiochemical and high performance liquid chromatography (HPLC) techniques.2.2. Exposure of animals to reduced salinity does not alter the rate of unidirectional alanine influx.3.3. In 34%o salinity, entry of labeled alanine reflects the net flux of the amino acid. However, in 17%o salinity, there is a net loss of alanine and other acids, mainly taurine, to the medium.4.4. Reduced salinity induces greater incorporation of radiolabeled FAA into macromolecular fractions throughout the animal.5.5. The major factors …
Influx And Transepithelial Flux Of Amino Acids In The Mussel, Mytilus Edulis., Michael A. Rice, Grover C. Stephens
Influx And Transepithelial Flux Of Amino Acids In The Mussel, Mytilus Edulis., Michael A. Rice, Grover C. Stephens
Michael A Rice
The uptake of amino acids by the non-gill epithelia of the mantle cavity of Mytilus edulis L. was studied and compared with uptake by the gills. Amino acid entry rates and the subsequent distribution of amino acids to the other tissues of the animals were studied using high-performance liquid chromatography and radiochemical techniques. Uptake via the non-gill epithelia lining the mantle cavity was separated from uptake via the gill by employing a preparation in which the gills were surgically removed. Amino acid uptake by such animals was compared with that of suitably sham-operated controls. In short-term experiments (up to 2h), …
Uptake And Internal Distribution Of Exogenously Supplied Amino Acids In The Pacific Oyster, Crassostrea Gigas (Thunberg), Michael A. Rice, Grover C. Stephens
Uptake And Internal Distribution Of Exogenously Supplied Amino Acids In The Pacific Oyster, Crassostrea Gigas (Thunberg), Michael A. Rice, Grover C. Stephens
Michael A Rice
A technique is described in which irrigation of the mantle cavity of oysters, Crassostrea gigas, induces pumping at steady rates. Simultaneous net influx of 10 amino acids (asp, glu, asn, ser, gly, tau, ala, val, phe, lys) is observed by high-performance liquid chromatography (HPLC). Individual amino acids exhibit first-order exponential depletion from an initial medium concentration of 2.0 μM. Influx of radiolabeled alanine corresponds very closely to net entry of alanine as estimated by HPLC. Therefore, net entry of alanine from dilute solution (5 μM) occurs. The entry of alanine is well described by Michaelis-Menten kinetics with a maximum influx …
Autoradiographic Localization Of Exogenously Supplied Amino Acids After Uptake By The Polychaete, Glycera Dibranchiata Ehlers, Paul Chien, Michael Rice
Autoradiographic Localization Of Exogenously Supplied Amino Acids After Uptake By The Polychaete, Glycera Dibranchiata Ehlers, Paul Chien, Michael Rice
Michael A Rice
Localization of amino acid transport sites within the integument of Glycera dibranchiata Ehlers was carried out by freeze-section and freeze-dry histological techniques. The worms were exposed for one hour to the non-metabolizable amino acid analog c(14)-cycloleucine in seawater. Freeze-sectioning and freeze drying of tissue samples allows the localization of water soluble compounds by autoradiography. Amino acid uptake is largely across the parapodial gill surfaces and the epidermis. The gills become rapidly labelled with c(14)-cycloleucine to a greater extent than the epidermal cell layers. Coelomocytes within the gills become radiolabeled in one hour. It is suggested that the rapid labelling of …
Transport Of Dissolved Amino Acids By The Mussel, Mytilus Edulis: Demonstration Of Net Uptake From Natural Seawater, Donal T. Manahan, Stephen H. Wright, Grover C. Stephens, Michael A. Rice
Transport Of Dissolved Amino Acids By The Mussel, Mytilus Edulis: Demonstration Of Net Uptake From Natural Seawater, Donal T. Manahan, Stephen H. Wright, Grover C. Stephens, Michael A. Rice
Michael A Rice
High-performance liquid chromatography provides direct evidence for substantial removal of naturally occurring specific free amino acids during a single passage of water through the mantle cavity of mussels. This occurs during the few seconds required for passage of the water across the gill, and removal proceeds unabated at ambient concentrations as low as 38 nanomoles per liter.