Anguilla Rostrata Le Sueur Research Articles

Anoxic performance of the American eel (Anguilla rostrata L.) heart requires extracellular glucose

The importance of extracellular glucose in the maintenance of performance of the heart of the American eel (Anguilla rostrata Le Sueur (L.) Under anoxia was assessed under a variety of experimental conditions. Ventricular strips, electrically paced at 36 bpm, in N(2)-gassed medium maintained the imposed pace rate and generated approximately 25% of the initial twitch force of contraction for at least 60 min when glucose was present in the medium. But ventricular strips challenged without glucose in the medium failed to maintain the pacing rate within 5-10 min. Isolated and intact, perfused hearts maintained pressure and followed an imposed pace rate of 24 bpm for at least 2 hr, under anoxic conditions, if glucose was present in the medium. But without glucose in the medium isolated hearts failed within 30 min. Endogenous glycogen stores were utilized in hearts perfused with medium containing NaCN to impair oxidative phosphorylation. The presence of glucose in the medium did not protect against glycogen mobilization. The data indicate that exogenous glucose is necessary to maintain performance under anoxia at high workloads and physiological Ca(2+) levels. Finally, ventricular strips treated with NaCN and forced to contract at 24 bpm lost 70% of initial twitch force. Increasing extracellular Ca(2+) concentration stepwise from 1.5 to 9.5 mM restored twitch force to approximately 50% of the initial level and this response was not dependent on exogenous glucose. However, glucose was required to maintain resting tension even under normoxic conditions in the face of a Ca(2+) challenge.

Characterization of gluconeogenesis in hepatocytes isolated from the American eel,Anguilla rostrata LeSueur,

Isolated hepatocyte preparations from fed immature American eels,Anguilla rostrata Le Sueur, were used to study gluconeogenic, lipogenic, glycogenic and oxidative rates of radioactively labelled lactate, glycerol, alanine and aspartate. Eel hepatocytes maintain membrane integrity and energy charge during a 2 h incubation period and are considered a viable preparation for studying fish liver metabolism.

Regulatory properties of pyruvate kinases isolated from tissues of the American eel, Anguilla rostrata le sueur

1. 1. American eel muscle (red and white) pyruvate kinases (PK) are sensitive to FDP ‡, ATP, l-ala and H +-ions. White muscle (WM)-PK is more sensitive to these effectors at both K m (PEP) and V max , but FDP overrides the inhibitory effects of both ATP and l-ala, and to a great extent eliminates any pH effect. This regulatory pattern is associated with the necessity for a high degree of metabolic integration in a tissue with a low resting metabolic demand, but a high active metabolic demand as previously suggested. 2. 2. Red muscle (RM)-PK is insensitive to H +-ions and is not as sensitive to FDP as the WM-enzyme. FDP does not override ATP or l-ala inhibition at V max , but it does set the K m(PEP) independent of inhibitors and pH. These characteristics provide integration between glycolysis and fatty acid oxidation. 3. 3. Eel liver (Lv)-PK is non-regulatory and this feature is discussed.

The induction of maturation of female American eels through hormone injections

1. Female American eels (Anguilla rostrata Le Sueur) were induced to mature by injecting silver migratory forms with powdered carp pituitaries. 2. The eggs of mature American eels resemble closely those of the European and Japanese eels, i. e. they are small (1 mm), almost spherical and have oil droplets within; thus, they appear to be pelagic. 3. The number of eggs of one mature specimen was in the range 1.3 to 1.5 × 106. 4. Purified ovine LH was not an efficacious gonadal stimulant in female American eels. 5. A unique and pungent odor detectable from the skin and mucus of matured and partially matured eels is described for the first time.

Genetic variation in the eel. III. Comparisons of Rhode Island and Icelandic populations. Implications for the Atlantic eel problem

The frequencies of certain electrophoretic fractions of esterases, transferrins and haemoglobins in an American sample of eels (Anguilla rostrataLe Sueur) are compared to those in a sample from Iceland [A. anguilla (L.)]. A number of quantitative differences were established as well as 6 contrasts of a qualitative all-or-none type. The bearing of these differences and contrasts on theories concerning a separate or a single gene pool for Atlantic eels is discussed.