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Ultrastructure Of The Coeloms Of Auricularia Larval (Holothuroidea Echinodermata): Evidence For The Presence Of An Axocoel, E. J. Balser, E. E. Ruppert, William Jaeckle

William Jaeckle

A hallmark feature of echinoderm larvae is the development of the left anterior coelom. This coelom, called the axohydrocoel, consists of the morphologically distinct, but undivided, left axocel and hydrocel. The axocoelic portion forms a duct that opens to the exterior via a pore on the dorsal surface of the animal. Holothuroid larvae are thought to lack an axocoel, but develop an anterior coelom, duct, and pore that are regarded as parts of the hydrocoel. New ultrastructural data, however, show that holothuroid auricularia larvae possess an axocel and hydrocel united together into an axohydrocoel. During development the anterior coelom consists …

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 …

The Alpha-Adrenergic Stimulation Of Atrial Natriuretic Factor Expression In Cardiac Myocytes Requires Calcium Influx, Protein Kinase C, And Calmodulin-Regulated Pathways, C A. Sei, C E. Irons, A B. Sprenkle, P M. Mcdonough, J H. Brown, C C. Glembotski

Amy Sprenkle

Action Of Heptaminol Hydrochloride On Contractile Properties In Frog Isolated Twitch Muscle Fibre, Bruno Allard, Vincent Jacquemont, Fouad Lemtiri-Chlieh, Bernard Pourrias, Oger Rougier

fouad Lemtiri-Chlieh

1 Heptaminol stopped or delayed the progressive decline in tension which characterizes the phenomenon of fatigue in frog isolated twitch muscle fibre. 2 Heptaminol had no action on the sodium, potassium and calcium voltage-dependent ionic conductances. 3 The hypothesis of an action via an internal alkalinization was tested by comparison with the action of NH4Cl. Both substances increased the tension. 4 The action of hepataminol was suppressed in sodium-free (TRIS) solution or in the presence of amiloride while the action of NH4Cl was always observed. 5 These results could be explained by a stimulation of the Na/H antiport by heptaminol.

Alternative Temporal Control Systems For Hypodermal Cell Differentiation In Caenorhabditis Elegans, Zhongchi Liu, Victor Ambros

Victor R. Ambros

Beginning of article: In certain multicellular organisms, genetic regulatory systems that specify the timing of cell division, differentiation and morpho-genesis must accommodate environmental and physiological contingencies that perturb or arrest development. For example, Caenorhabditis elegans can either develop continuously through four larval stages (L1–L4) or arrest indefinitely as a 'dauer larva' at the second larval (L2) moult, and later resume L3 and L4 development. At the larva-to-adult (L4) moult of both con-tinuous and 'post-dauer' development, hypodermal cells switch (the 'L/A switch') from a proliferating state to the terminally differentiated state. Four temporal regulators, lin-4, lin-14, lin-28 and lin-29, have been …

Patterns Of Ionic Currents Around The Developing Oocyte Of The Cockroach, Blattella Germanica., Joseph Kunkel

Joseph Kunkel

The development of patterns of current around vitellogenic oocytes of the cockroach, Blattella germanica, was examined by means of a two-dimensional vibrating probe. Previtellogenic oocytes exhibited small unstable currents. Shortly after vitellogenic uptake began (oocytes 0.6-0.8 mm anterior to posterior) currents were either all inward or all outward at the plane of measuiement. A dorsoventral pattern of currents was first observed around oocytes a little larger than 0.8 mm. Current exited dorsally (source) and entered ventrally (sink). In these oocytes source and sink were small, less than half the anterior-posterior length. As oocytes grew, relative sizes of source and sink …

Amino Acid Uptake And Metabolism By Larvae Of The Marine Worm Urechis Caupo (Echiura), A New Species In Axenic Culture, William Jaeckle, Donal T. Manahan

William Jaeckle

Axenic (bacteria-free) larval cultures of the marine echiuran worm, Urechis caupo, were reliably obtained by aseptically removing gametes directly from the gamete storage organs. Trochophore larvae only removed neutral amino acids from seawater as measured by high-performance liquid chromatography (HPLC). There was no detectable uptake, as measured by HPLC, of acidic or basic amino acids. Kinetic analysis showed that the transport system for alanine in 4-day-old larvae had a Kt of 4-6 μM and a Jmax of 9-10 pmol larva-1 h-1. Following a 50-min exposure, the majority of the radio-activity (95%) from 14C-alanine was found in the trichlo-roacetic acid-soluble fraction. …

Feeding By A “Nonfeeding” Larva: Uptake Of Dissolved Amino Acids From Seawater By Licithotrophic Larvae Of The Gastropod Haliotis Refescens, William Jaeckle

William Jaeckle

No abstract provided.

Growth And Energy Imbalance During The Development Of A Lecithotrophic Molluscan Larva (Haliotis Rufescens), William Jaeckle, Donal T. Manahan

William Jaeckle

Larvae of the gastropod Haliotis rufescens are classified as "nonfeeding" because they cannot capture particular foods. However, for only 1 out of 5 independent cultures was a net decrease observed in dry organic weight during the complete period of larval development (5 to 7 days). In fact, there were net increases in dry organic weight from the oocyte (day 0) to the newly formed veliger larvae (2-day-old). These weight increases during early development could be explained by increases in the amounts of specific biochemical components of the larvae, relative to oocytes. The metabolic rates of larvae were measured (oxygen consumption) …

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 …

Stressors In The Learned Helplessness Paradigm: Effects On Body Weight And Conditioned Taste Aversion In Rats., Clinton Chapman, Nancy Dess, John Garcia, Jeffrey Raizer

Clinton D Chapman

In Exp 1, 44 male rats drank saccharin or a control solution, followed by 100 inescapable shocks or simple restraint. Ss were weighed daily and were tested for saccharin aversion 2 days after the stress session. Shocked Ss gained less weight than restrained controls. Saccharin aversion was apparent only among Ss that had consumed saccharin before the stress session. In Exp 2, 72 Ss drank saccharin solution, followed by shock, restraint, or no treatment. Half of each group was injected with saline; the other half was injected with lithium chloride. Shock reduced body weight relative to restraint or no treatment …

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

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

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

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.