Stimulation of Balanus balanoides and Fundulus heteroclitus by Dicarboxylic Acids

1937 ◽  
Vol 10 (3) ◽  
pp. 327-341
Author(s):  
Irwin W. Sizer
Keyword(s):  
Fundulus Heteroclitus ◽  
Dicarboxylic Acids ◽  
Balanus Balanoides ◽  
Stimulation Of

Toxicity and environmental requirements of a strain of Aphanizomenon flos-aquae (L.) Ralfs

1969 ◽  
Vol 15 (2) ◽  
pp. 165-173 ◽  
Author(s):  
John H. Gentile ◽  
Thomas E. Maloney
Keyword(s):  
Fundulus Heteroclitus ◽  
Maximum Growth ◽  
Defined Medium ◽  
Culture Temperature ◽  
Ph Optimum ◽  
Naturally Occurring ◽  
Environmental Requirements ◽  
Daphnia Catawba ◽  
Phosphorus Levels ◽  
Stimulation Of

A toxic strain of Aphanizomenon flos-aquae was isolated and cultured in a defined medium (ASM-1). This strain fixes nitrogen, has a pH optimum of 7.5, and has maximum growth rates at 5000 lux and 26 °C. Phosphorus levels of 1.0 μM readily supported populations of 1 × 105 cells/ml with stimulation of growth evident at a concentration of 0.1 μM P. Tris is inhibitory to growth of this alga at concentrations above 2.5 mM.Toxin production is related to age of culture, temperature, and light intensity but not nitrogen source.Intraperitoneal injection of toxic extracts into Fundulus heteroclitus, Cyprinodon variegatus, and white mice gave a LD100 of 0.5 mg/kg, 0.5 mg/kg, and 8 mg/kg, respectively. Assays with Notemigonus crysoleucas and Bosmina longirostris indicate that the toxin from naturally occurring bloom populations (1 × 106 cells/ml), if released all at once, would be capable of killing certain species of fish and microcrustaceans. Daphnia catawba, however, was much more resistant to toxin (LD100 = 1.0 mg/ml) while cyclopoid copepods, ostracods, and chydorid cladocerans were completely unaffected by toxin concentrations of 2.0 mg/ml. The possible ecological significance of this toxic alga in relation to fish kills is also discussed.

scholarly journals The Control of Photo-Pigmentary Responses in Eyeless Catfish

1938 ◽  
Vol 15 (3) ◽  
pp. 363-370
Author(s):  
URSULA WYKES
Keyword(s):  
Fundulus Heteroclitus ◽  
Posterior Part ◽  
Bright Light ◽  
The Body ◽  
Nervous Control ◽  
Low Frequencies ◽  
Spinal Nerves ◽  
The Brain ◽  
Photic Response ◽  
Stimulation Of

1. In common with certain other teleosts and lacertilians, eyeless Amiurus nebulosus and Fundulus heteroclitus show a pigmentary response to changes in intensity of illumination. The melanophores contract in the darkness and expand in bright light. The control of this photic response was investigated in Amiurus. 2. The contraction in darkness was not obtained in areas denervated by section of spinal nerves nor in the posterior part of the body after section of the cord. The response is therefore under the control of nervous reflexes passing through the brain. A similar melanophore contraction can be obtained by electrical stimulation of the cord at extremely low frequencies. 3. The response remained in pinealectomized animals. Photoreceptors may possibly be located in the skin or the wall of the diencephalon may be sensitive to light. 4. After hypophysectomy the response continues but the degree of melanophore expansion in bright light is diminished. The expanding hormone of the pituitary is therefore important in that it augments a melanophore response which is under nervous control.

scholarly journals Pardaxin Produces Sodium Influx in the Teleost Gill-like Opercular Epithelia

1983 ◽  
Vol 105 (1) ◽  
pp. 83-94
Author(s):  
NAFTALI PRIMOR
Keyword(s):  
Active Transport ◽  
Red Sea ◽  
Fundulus Heteroclitus ◽  
Serosal Side ◽  
Na Current ◽  
Sodium Influx ◽  
Active Transport Of Ions ◽  
Transport Of Ions ◽  
Mucosal Side ◽  
Stimulation Of

1. Transport by the gill-like opercular epithelium of the teleost, Fundulus heteroclitus, was affected by pardaxin, a protein that is toxic to fish, isolated from the Red Sea flatfish Pardachirus marmoratus. 2. Administration of pardaxin to the mucosal (seawater) side of the isolated short-circuited opercular epithelium, caused a transient stimulation of the active transport of ions (Isc), followed by an inhibition. The Isc stimulation was abolished by ouabain or/and in Na+-free Ringer but not in Cl−-or HCO3−-Ringer. When applied to the serosal (blood) side, pardaxin did not affect the Isc. 3. Pardaxin produced a net transient Na+ current from the mucosal side to the serosal side of 2.2 μequiv cm−2h−1. It is concluded that this Na+influx caused the Isc stimulation. The influx is suggested to be the mechanism of pardaxin's toxicity in fish.

Effect of atriopeptin II on isolated opercular epithelium of Fundulus heteroclitus

1988 ◽  
Vol 254 (1) ◽  
pp. R27-R32 ◽  
Author(s):  
J. I. Scheide ◽  
J. A. Zadunaisky
Keyword(s):  
Fundulus Heteroclitus ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Chloride Secretion ◽  
Chloride Cells ◽  
Induced Response ◽  
Ion Regulation ◽  
Cyclic Monophosphate ◽  
Stimulation Of

The effect of atriopeptin II (ANF) on the in vitro opercular epithelium was investigated by use of short-circuit current techniques. Serosal addition of ANF stimulates chloride secretion (short-circuit current) 19% above control values with a 7% increase in tissue conductance. Mucosal addition of ANF to the opercular epithelium was without effect. The ANF stimulation of the current was dose dependent with a maximum at 10(-7) M. The addition of ANF had no effect on the current or the conductance of opercular epithelia bathed in Cl--free Ringer. The opercular current could be stimulated above the ANF response by isoproterenol (10(-6) M). Pretreatment of the opercular epithelium with propranolol (10(-5) M) did not inhibit the stimulation of the short-circuit current by ANF but did inhibit the isoproterenol response indicating that the ANF stimulatory activity was independent of the beta-adrenergic receptors. The ANF-stimulated short-circuit current was found in operculi pretreated with tetrodotoxin (10(-6) or 10(-5) M) or diltiazem (10(-4) M) indicating the ANF response was not due to nerve stimulation. Pretreatment of opercular tissue with dibutyryl adenosine 3',5'-cyclic monophosphate, 8-bromoadenosine 3',5'-cyclic monophosphate, or 8-bromoguanosine 3',5'-cyclic monophosphate (10(-4) M) had no effect on the ANF stimulatory response. Opercular epithelia from short-term freshwater-adapted killifish also showed the ANF-induced response. The stimulation of chloride secretion in Fundulus heteroclitus chloride cells by ANF may have a role in teleost ion regulation.

Effects of 5-5'-Diphenyl-2-thiohydantoin (DPTH) and Thyroxine on the Ultrastructure and Chemical Composition of Rat Liver

1971 ◽  
Vol 29 ◽  
pp. 570-571
Author(s):  
E. A. Elfont ◽  
R. B. Tobin ◽  
D. G. Colton ◽  
M. A. Mehlman
Keyword(s):  
Chemical Composition ◽  
Rat Liver ◽  
Future Study ◽  
Mode Of Action ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Effective Inhibitor ◽  
Biochemical Effects ◽  
Glycerophosphate Dehydrogenase ◽  
Stimulation Of

Summary5,-5'-diphenyl-2-thiohydantoin (DPTH) is an effective inhibitor of thyroxine (T4) stimulation of α-glycerophosphate dehydrogenase in rat liver mitochondria. Because this finding indicated a possible tool for future study of the mode of action of thyroxine, the ultrastructural and biochemical effects of DPTH and/or thyroxine on rat liver mere investigated.Rats were fed either standard or DPTH (0.06%) diet for 30 days before T4 (250 ug/kg/day) was injected. Injection of T4 occurred daily for 10 days prior to sacrifice. After removal of the liver and kidneys, part of the tissue was frozen at -50°C for later biocheailcal analyses, while the rest was prefixed in buffered 3.5X glutaraldehyde (390 mOs) and post-fixed in buffered 1Z OsO4 (376 mOs). Tissues were embedded in Araldlte 502 and the sections examined in a Zeiss EM 9S.Hepatocytes from hyperthyroid rats (Fig. 2) demonstrated enlarged and more numerous mitochondria than those of controls (Fig. 1). Glycogen was almost totally absent from the cytoplasm of the T4-treated rats.

Gap junctions in the prothoracic glands of the tobacco hornworm, Manduca sexta

1992 ◽  
Vol 50 (1) ◽  
pp. 706-707
Author(s):  
Ji-da Dai ◽  
M. Joseph Costello ◽  
Lawrence I. Gilbert
Keyword(s):  
Gap Junctions ◽  
Small Molecules ◽  
Manduca Sexta ◽  
Freeze Fracture ◽  
Cell Communication ◽  
Cellular Level ◽  
Thin Sections ◽  
Prothoracic Glands ◽  
Polyhydroxylated Steroids ◽  
Stimulation Of

Insect molting and metamorphosis are elicited by a class of polyhydroxylated steroids, ecdysteroids, that originate in the prothoracic glands (PGs). Prothoracicotropic hormone stimulation of steroidogenesis by the PGs at the cellular level involves both calcium and cAMP. Cell-to-cell communication mediated by gap junctions may play a key role in regulating signal transduction by controlling the transmission of small molecules and ions between adjacent cells. This is the first report of gap junctions in the PGs, the evidence obtained by means of SEM, thin sections and freeze-fracture replicas.

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