Water and lactate movement in the swimbladder of the eel, Anguilla anguilla.

Hemoglobin (Hb) and lactate (La) concentrations were measured in small (150 microliters) blood samples collected with micropipettes from the inflow and outflow vessels of the rete mirabile of the eel swimbladder. Hemoglobin was used as a marker of the intravascular space. 1. Hemoglobin concentrations suggest that there was no significant water movement between the arterial and venous capillaries in the rete, but a significant 6% water efflux from the vascular space into the swimbladder epithelium. No significant differences in osmolality were observed between the sites of measurement. 2. Of the lactate present in the blood entering the venous capillaries of the rete, 30% derived from release by the swimbladder epithelium; 38% of the lactate entering the venous capillaries diffused back in the rete tissue into its arterial capillaries. 3. Theoretical models suggest that any water movement in the swimbladder, leading to blood flow mismatch in the rete counter-current system, reduces its efficiency to concentrate inert gases, whereas lactate back-diffusion enhances this efficiency.

Sources of carbon dioxide in penguin air sacs.

CO2 tensions in the caudal air sacs of birds cannot be quantitatively predicted by current models of avian respiration, mainly because the contribution of neopulmonic parabronchial gas exchange has not been determined. To overcome this problem we studied penguins that have purely paleopulmonic lungs. Three penguins were anesthetized, intubated, and ventilated at a constant respiratory rate and different tidal volumes (VT). PO2 and PCO2 were measured in arterial blood and end-expired, mixed-expired, interclavicular air sac, and caudal thoracic air sac gas. Interclavicular air sac and end-expired gas had similar compositions. Caudal thoracic air sac gas was intermediate in composition to end-expired and inspired gas, and its PCO2 was 1.5-3.5 times greater than the value predicted from reinhaled dead space. This difference between measured and predicted caudal thoracic air sac PCO2 increased with VT but showed no relationship to changes in dead space-to-VT ratio. The difference is not explained by stratification or diffusive gas exchange across air sac walls. The results can be explained by postulating that inspired gas passes over exchange surfaces on its path to caudal air sacs. This is unexpected in the purely paleopulmonic lungs of penguins and suggests that airflow may not be caudocranial in all paleopulmonic parabronchi.

Collagen hydrolysis by a new Streptomyces species.

A soil streptomycete hydrolysed collagen extracted from bovine Achilles tendon, calf skin, carp swim bladder and rat tail tendon. Enzyme activity was highest with rat tail tendon collagen as substrate. The taxonomy of the streptomycete was studied according to internationally approved methods. Comparative studies revealed that it resembled Streptomyces humidus , S. rochei and S. distatochromogenes in some respects, but differed in many cultural and physiological characteristics. Based on these differences the organism was given a new identity as Streptomyces species A.

Swimbladder membrane protein of an abyssal fish, Coryphaenoides acrolepis.

Protein components of the membranous foamy tissue collected from the swimbladder of Coryphaenoides acrolepis, a continental slope/deep sea grenadier fish, were partially fractionated and characterized by procedures used successfully for erythrocyte membrane proteins. Methods involving pH and ionic strength adjustment in the presence of EDTA and beta-mercaptoethanol resulted in some protein fractionation but no distinct separation or isolation of membrane proteins. Gel filtration by Sephadex G-100 and Sepharose 2B in the presence of dodecyl sulfate partially fractionated protein species between 18,000 and 150,000 molecular weight (as confirmed by dodecyl sulfate polyacrylamide gel electrophoresis). Low molecular weight proteins were resolvable into a few diffuse and streaky bands by dodecyl sulfate and chloral hydrate polyacrylamide gel electrophoresis, the former giving superior reso-ution. A major fraction of large molecular weight protein (greater than or equal to 40 X 10(6)) was not resolved by any method. A possible explanation for these unusual findings is that decompression due to rapid ascent of the fish from deep ocean caused irreversible alteration of swimbladder membrane proteins.

Gas content of swim bladder of Wallago attu and oxygen consumption in Isoparorchis hypselobagri (Trematoda).

The swim bladder gas of Wallago attu contains O2 (22-58 mm Hg) and the presence or absence of Isoparorchis hypselobagri does not influence the O2 content of the swim bladder. Glucose increases the O2 consumption of I. hypselobagri by 50%. With the passage of in vitro culture time, the rate of O2 consumption gradually decreases to the extent of 64% on the 40th day. The optimal temperature for O2 consumption is 30 degrees C beyond which the rise in temperature is detrimental to the fish trematode as manifested by the decrease in their O2 consumption.

Composition of lipid foams from swim bladders of two deep ocean fish species.

Lipid-containing deposits within the swim bladders of Coryphaenoides acrolepis and Antimora rostrata were investigated. Lipid analysis of this material, which was quite uniform from the two species, yielded the following data: neutral lipids, 36.0-41.7%; phospholipids, 53.6-56.7%; and glycolipids, 4.3-8.9%. Cholesterol (mainly in the free form) constituted 60.4%-77.8% of the neutral lipids. Sphingomyelin and phosphatidylcholine were the principal phospholipids, with sphingomyelin highest in the material from C. acrolepis and phosphatidylcholine predominant in that from A. rostrata. The overall pattern of lipids shows a resemblance to that of plasma membrane, particularly in the relatively high levels of free cholesterol, sphingomyelin, and phosphatidylserine. The lipid-to-protein ratio of the material is approximately 1.5-2 to 1. The lipids of the fine inner lining (tunica interna) of the swim bladder from a shallow water fish, the kelp bass (Paralabrax clathratus), had essentially the same composition as the much more abundant swim bladder material from the deep ocean fishes.