Treatment with thiamine hydrochloride and astaxanthine for the prevention of yolk-sac mortality in Baltic salmon fry (M74 syndrome).

Two practical methods are reported for treating feral Baltic salmon with thiamine hydrochloride against M74 syndrome (abnormally high yolk-sac fry mortality of the Baltic salmon). Both bathing of the yolk-sac fry in thiamine hydrochloride (1000 mg l-1, 1 h) and a single intraperitoneal injection given to the female brood fish (100 mg kg-1 fish) during the summer 3 mo before stripping were shown to elevate the whole body total thiamine concentration in the fry. Both treatments were also shown to be effective in preventing mortality due to M74 syndrome. The effect of bathing the yolk-sac fry was shown to be dose-dependent. The results support the view that there is a causal relationship between the thiamine status of the yolk-sac fry and M74 mortality. An intraperitoneal injection of astaxanthine suspension administered to the female brood fish (11 mg kg-1 fish) in the summer 3 mo before stripping elevated the astaxanthine concentration in the eggs but did not affect mortality due to M74 syndrome. An interaction between astaxanthine and thiamine may occur in the developing embryo or yolk-sac fry, however. No association could be demonstrated between the various thiamine hydrochloride treatment practices and hepatic cytochrome P450 dependent 7-ethoxyresorufin-O-deethylase (EROD) activity in the yolk-sac fry. An injection of thiamine hydrochloride into the peritoneal cavity of wild Baltic salmon females could be used to raise thiamine concentrations in their offspring in the rivers. The effect on smolt production in Finnish Baltic salmon rivers needs to be investigated further, however.

Seasonal changes in certain metabolic and haematologic responses of Salmo gairdneri acutely exposed to dehydroabietic acid (DHAA).

Physiological effects of a high sublethal DHAA exposure on respiration, ammonia excretion and haematology of rainbow trout were studied in July at 15 degrees C and in December at 10 degrees C. In the control fish plasma glucose concentration was higher (P less than 0.001) in December than in July, but plasma protein (P less than 0.02) and Na+ (P less than 0.001) concentrations were lower. Due to DHAA exposure the oxygen consumption (P less than 0.01) and ammonia excretion rates (P less than 0.001) increased significantly in July but not in December. In December a significant decrease in plasma Cl- and increase in plasma protein concentration occurred with a slight haemoconcentration. Microscopic examination of the gills, performed on the trout in December only, revealed a 25% hypertrophy of secondary lamellar structures due to the exposure.

Blood oxygen transport of hypoxic Salmo gairdneri.

The in vivo blood oxygen binding properties of rainbow trout were studied in normoxia and hypoxia (PO2 55-60 mmHg). Owing to hypoxia the in vivo oxygen dissociation curve of blood was shifted to the left; the P50 value decreased from 37 mmHg in normoxia to 27 mmHg in hypoxia. Hypoxia also caused an increase in the erythrocytic volume, a decrease in the concentrations of ATP and hemoglobin inside the cell, and an increase in the intraerythrocytic pH. All these responses are interrelated. The swelling of the erythrocytes decreased the concentrations of ATP and Hb in the cell. This decrease changed the Donnan distribution of protons across the red cell membrane, thus increasing the intraerythrocytic pH. The increase in the intraerythrocytic pH was the main cause of the increase in the blood oxygen affinity. Owing to the increased blood oxygen affinity the oxygen transport from gills to tissues in hypoxia was only slightly decreased from that in normoxia. However, as the venous oxygen tension decreased in hypoxia, the diffusion of oxygen from tissue capillaries to the cells was probably slowed down in hypoxia when compared to normoxia.

Oxygen transfer, gill resistance and structural changes in rainbow trout (Salmo gairdneri, Richardson) gills perfused with vasoactive agents.

1. Gill resistance (Rg) and oxygen transfer (To2) were measured in perfused rainbow trout gills. After perfusion the gills were analysed morphometrically. 2. Rg increased with 40% and To2 decreased with 91% during 60 min perfusion without vasoactive substances in the perfusion Ringer. 3. In presence of 10 micro M adrenaline both Rg and To2 remained stable at their starting levels throughout the experimental period (60 min). 4. With 0.2 micro M acetylcholine and 10 micro M adrenaline in Ringer Rg increased nearby to the same extent as in perfusions without vasoactive agents, while To2 was not significantly affected. 1 micro M acetylcholine increased Rg with 76% and decreased To2 with 51%. 5. The changes in Rg and To2 could be explained by structural changes in the secondary lamellae.

Comparison of induced and spontaneous arousals in hibernating hedgehogs.

Respiratory and circulatory differences between periodic spontaneous arousals and induced arousals in hibernating hedgehogs were studied in a constant ambient temperature of + 4.2 +/- 0.5 oC. The increase in O2 consumption, blood pressure and heart rate was faster during induced arousals than during periodic spontaneous arousals. Based on our present studies we suggest that even the smallest stimulus able to induce the awakening is sufficient to modify the process so that it differs markedly from a spontaneous arousal.

The distribution of the hedgehog (Erinaceus europaeus L.) in Finland in 1975.

The distribution of the hedgehog (Erinaceus europaeus L.) in Finland was surveyed in the light of an inquiry. The range presented is based on more than one thousand answers to a questionnaire. The extension further northward of this species during the past ten years was confirmed. The distributional areas of the hedgehog in Finland in 1952, 1965 and 1975 are presented in a cartogram. In southern Finland the number of the hedgehog has clearly decreased during the past ten years (1965-1975). Some possible reasons for the decline are discussed.

On the [4-14C]progesterone metabolism of keloid and hypertrophic scar. A preliminary report.

Tissue specimens from keloids (K) and hypertrophic scars (H), as well as from the healthy skin in their vicinity (KS resp. HS) were incubated in a medium containing [4-14C]progesterone. The metabolites were isolated and verified with thin layer chromatography. All investigated tissue types produced as metabolites of progesterone 5 alpha-pregnane-3,20-dione, 5 alpha-pregnane-3 alpha, 20 alpha-diol, as well as probably 3 alpha/beta-hydroxy-5-pregnan-20 one. The diffusion of progesterone from the medium into the tissue was most effective in K, in sharp contrast to H. The ability of the tissue to take up progesterone from the medium was nearly double in HS as compared with KS. HS seems to metabolize progesterone nearly with the same effectivity as K, and those both twice as much as KS. There were also marked differences in the division of metabolites between the tissue and the medium.

A technique for repeated sampling of the blood of individual resting fish.

A dorsal cannulation technique is described. It has been employed for repeated blood sampling in unanaesthetized rainbow trout (Salmo gairdneri) kept singly in special receptacles described in the paper. The level of the studied haematological parameters (Haematocrit, Hb, glucose, lactate, K+, Na+, Ca2+) differed between fish kept in receptacles for 1 week and free-swimming fish, most probably owing to differences in the motility of the fish. The receptacle seems to minimize visual and handling disturbances, and permits both the standardization of experimental conditions and quick and easy sampling via the dorsal aorta cannula. The general variation in the blood parameter values was very small compared with the previously reported variation in such values for rainbow trout.