Haematology of juvenile Acipenser oxyrinchus and Acipenser brevirostrum at rest and following forced activity

In vivo experiments were conducted to examine the haematology of juveniles from two relic bony fishes, Atlantic sturgeon Acipenser oxyrhinchus and shortnose sturgeon Acipenser brevirostrum . Oxygen transport characteristics (haematocrit, haemoglobin and mean erythrocytic haemoglobin concentration), ionic composition (Na⁺, Cl⁻, K⁺ and osmolality), metabolite concentration (lactate, cortisol and glucose) and protein content in blood were measured or calculated at rest and during recovery from forced activity. Under resting conditions, plasma osmolality and concentrations of Na⁺, Cl⁻, lactate, cortisol and total protein were significantly different between Atlantic and shortnose sturgeon. All other resting variables were not different between species. Following forced activity, plasma lactate levels were significantly higher in both species than at rest. Plasma cortisol levels in both species were only significantly higher 1 h following forced activity compared to resting values. Plasma lactate levels were significantly higher in Atlantic sturgeon than in shortnose sturgeon, but these levels returned to resting levels by 1 h in both species. Cortisol increases were greater in shortnose sturgeon than in Atlantic sturgeon. In general, oxygen transport characteristics, blood glucose, plasma protein and plasma osmolality were not altered by forced activity in either sturgeon species. Overall, both species had reduced responses ( i.e . the magnitude of changes in measured variables) to forced activity compared with teleosts.     

Oxygen consumption of East Siberian cod: no support for the metabolic cold adaptation theory

Standard metabolic rate ( R _s) at 2°C of eight East Siberian cod Arctogadus borisovi , caught in West Greenland, body mass of 601.5 ± 147.6 g (mean ± s.D.), was 40.9 ± 5.9 mg O₂ kg^-1 h^-1 and 59.0 ± 6.6mg O₂ kg^-1 h^-1 when extrapolated to a standardized 100 g fish. R _s was compared with three other Gadidae, to test the theory of metabolic cold adaptation (MCA). There was no evidence of MCA in the family.     

Effect of excess vitamin D3 on calcium metabolism in rainbow trout Salmo gairdneri Richardson

The effect of excess vitamin D₃ on calcium metabolism in rainbow trout was investigated. Trout were reared for 24 weeks on diets containing 4000, 104 000 or 1 004 000 iu of supplemental vitamin D₃ kg^-1 dry diet. No effect of excess vitamin D₃ was detected in the weight gain, feed efficiency or total mortalities of trout in the different groups. None of the fish showed any signs of hypercalcaemia and no significant difference was detected in the calcium, magnesium, phosphorus and sodium content of the trout vertebrae or total carcass. However, there was a significant increase in the calcium, magnesium and phosphorus content of the skin in trout reared on the highest supplemental level of vitamin D₃ (1 004 000 iu kg^-1 diet). No overt signs of renal calcinosis were detected in any of the trout. This study indicates that trout are resistant to excess vitamin D₃, and that excess vitamin D₃ does not appear to be related to the increased incidence of renal calcinosis in rainbow trout.     

The induced spawning of roach, Rutilus rutilus (L.), with the antioestrogens clomiphene and tamoxifen

The induced spawning of gravid roach was investigated using the antioestrogens clomiphene and tamoxifen. Three dose levels ofeach were used: 0·1, l or 10 mgkg^-1, given twice with a 4-day interval to groups of eight fish with saline controls. Running males were randomly distributed. Tamoxifen, when injected at a rate of l mg kg^-1 was found to be most successful. This treatment induced ovulation in five of the six females, and profuse spawning on 3 consecutive days, 4 days after the first injection. Clomiphene induced ovulation and spawning in one of six females at 2 × 10 mg kg^-1, and two of eight females at 2 × l mg kg^-1, respectively 6 and 7 days after the first injection. The eggs produced showed normal devel-opment. No control fish ovulated or spawned. Both drugs probably act by indirect mechanisms, blocking sex steroid feedback inhibition of gonadotropin (GtH) secretion at the pituitary, thereby inducing a plasma GtH surge. The results of this experiment suggest that tamoxifen may be an effective substitute for pituitary preparations in the induced spawning of fish.     

Seasonal patterns in water, sodium and energy turnover in free-living echidnas, Tachyglossus aculeatus (Mammalia: Monotremata)

The energetics of an egg-laying mammal, the echidna ( Tachyglossus aculeatus ), were studied in the wild by means of isotope turnover techniques. Water and sodium influx rates were highest in summer (47.7±15.3 ml kg^-1 day^-1 and 1.20±0.52 mmol kg^-1 day^-1, respectively) and associated with high metabolic rates (0.509±0.048 ml CO₂ g^-1 h^-1). Water and sodium influxes and metabolic rates were lowest in May and June (7.8±6.4 ml H₂O kg^-1 day^-1, 0.21±0.12 mmol Na kg^-1 day^-1 and 0.205±0.129 ml CO₂ g^-1 h^-1, respectively). These low rates in late autumn/early winter are associated with reduced activity, the animals spending substantial periods of time in torpor. The comparatively low isotope turnover rates of echidnas are a consequence of their diet; ants and termites which have low mass-specific energy contents.     

Dietary vitamin E and the response of rainbow trout, Oncorhynchus mykiss (Walbaum), to infection with Yersinia ruckeri

Rainbow trout fed diets containing 7, 86 or 806 mg vitamin E kg⁻¹ for 22 weeks were exposed to virulent Yersinia ruckeri by bath or injection. Mortalities were always least among those fed the highest concentration of vitamin E but serum antibody production was not affected by vitamin E levels.     

Behaviour and performance of juvenile shortnose sturgeon Acipenser brevirostrum at different water velocities

Critical swimming speeds (mean ± s . e .) for juvenile shortnose sturgeon Acipenser brevirostrum were 34·4 cm s⁻¹± 1·7 (2·18 ± 0·09 body lengths, BL s⁻¹). Swimming challenges at 10, 20 and 30 cm s⁻¹ revealed that juvenile A. brevirostrum are relatively poor swimmers, and that the fish did not significantly modify their swimming behaviour, although they spent more time substratum skimming ( i.e. contact with flume floor) at 30 cm s⁻¹ relative to 10 cm s⁻¹. When present, these behavioural responses are probably related to morphological features, such as flattened rostrum, large pectoral fins, flattened body shape and heterocercal tail, and may be important to reduce the costs of swimming.     

Motility and fertilizing capacity of fresh and frozen-thawed spermatozoa in sturgeons Acipenser Baeri and A. ruthenus

The Siberian sturgeon ( Acipenser baeri ) and the sterlet ( A. ruthenus ) were injected with dried sturgeon pituitary (2 mg kg⁻¹), yielding 24 h later respectively 1.71 ± 0.5 and 1.65 ± 0.5 10¹¹ spermatozoa kg⁻¹ body weight. Spermatozoa were best activated with a solution of Tris HC1 50 mM, pH 8.0. The percentage of activated cells was 88 ± 4.4 in A. baeri (n = 5) and 68 ± 19 in A. ruthenus. (n = 5). In A. baeri , immediately after activation, the beat frequency of the flagellum and the mean velocity were in the range of 48–52 Hz and 100–300 μm⁻¹s, respectively. The beat frequency declined to 15 Hz at 30–40 and velocity to 100 μm s⁻¹ at 60 s post-activation. Only a small percentage of the spermatozoa remained motile after 3–4 min. In all cases spermatozoa showed mostly quasi-linear trajectories. Sperm was frozen in liquid nitrogen vapor immediately after dilution 1 v: 1 v in a cryopreservation medium (23.4 mM saccharose, 118 mM Tris-HCl pH 8.0, 20% egg yolk to which 15% DMSO were added). After fast-thawing procedure (25 s at 40°C), the percentage of motile spermatozoa (once activated in 118 mM Tris-HCl, pH 8.0) decreased to 23 ± 8.8 in A. baeri and to 15 ± 11 in A. ruthenus. The fertilizing capacity also decreased: 53 ± 8.3% vs. 89 ± 7.6% in control (P < 0.05) in A. baeri and 23 ± 11% vs 53 ± 8.3% in control (P < 0.05) in A. ruthenus. The motility pattern of the surviving frozen/thawed spermatozoa was the same as in fresh spermatozoa.     

Osmotic and structural changes during early development of eggs and larvae of the cod, Gadus morhua L.

Newly extruded cod eggs have a similar osmoconcentration ( c. 400 mosmol kg^-1) to maternal blood, maternal ovarian fluid and paternal semen. After extrusion, average egg osmolarities rise rapidly to about 520 mosmol kg^-1 but this is entirely due to the cortical reaction resulting in the formation of a perivitelline space filled with fluid isosmotic with the external medium. The ovoplasm remains at around 400 mosmol throughout development; free swimming cod larvae also possess body fluids of this concentration. Over the salinity range 10.2-37.4%₀, salinity had no effect on egg dimensions and average egg osmolarities were consistent with a model assuming changes in perivitellic fluid concentration only.     

Endothelin-1 Increases Arachidonic Acid Release in C6 Glioma Cells Through a Potassium-Modulated Influx of Calcium

Abstract: Endothelin-1 (Et-1) but not a range of other receptor agonists stimulated the release of arachidonic acid (AA) in C6 glioma. Et-1 activation was concentration dependent and was inhibited by chelation of extracellular calcium. The calcium ionophores A23187 and ionomycin could also stimulate release of AA. Et-1 caused an early increase in intracellular Ca²⁺ concentration ([Ca²⁺]_i) followed by a sustained but lower plateau level. The sensitivity of the response to quinacrine, its dependence on Ca²⁺, and the demonstration of an increase in phospholipase A₂ (PLA₂) activity that was insensitive to dithiothreitol suggested that the release of AA was due to activation of cytosolic PLA₂ in the cells. Staurosporine, a protein kinase C (PKC) inhibitor, had no effect on Et-1-induced AA release but abolished that by phorbol 12-myristate 13-acetate, demonstrating that the Et-1 response was PKC independent. Raised levels of extracellular KCI inhibited both AA release and the increase in [Ca²⁺]_i triggered by Et-1, whereas valinomycin, which causes K⁺ efflux, not only caused a rapid rise in [Ca²⁺]_i but also caused AA mobilisation. The results therefore suggest that Et-1 activation of PLA₂ in this cell type requires calcium influx dependent on K⁺ efflux.     

The arrangement of the heart chambers and associated blood vessels in the Devonian osteostracan Norselaspis glacialis. A reinterpretation based on recent studies of the circulatory system in lampreys

Food intake and digestion were investigated at four stages in the first 218 days of lactation in tammar wallabies ( Macropus eugenii ) carrying litters of one, and in non-lactating females as a control. This period of lactation in tammars, which includes the phase of exponential growth of the young, is comparable to gestation plus early lactation in ruminant placentals. Food and energy intakes by mothers remained at the non-lactating level while rate of growth of young was slow (up to Day 105 of lactation) but then rose as the growth rate of young increased, keeping pace with the predicted requirements for milk synthesis and export. There was no indication of the energy deficit seen in late gestation and early lactation in many herbivorous placental mammals. The gross efficiency of utilization of ME for growth of offspring was estimated as 13–15%, which is at least as high as values for placentals during gestation. The mean intake of metabolizable energy (ME) at 218 days was 603 kJ.kg^-0.75.d^-1, which represented 136% of ME intake by nonlactating females, or an increment of 159 kJ.kg^-0.75.d^-1. It was estimated that ME intake may rise to 773 kJ.kg^-0.75.d^-1 at peak lactation, which would be 174% of the non-lactating level or an increment of 329 kJ.kg^-0.75. d^-1. This allometrically-scaled increment is similar to values for some ruminants that use body reserves extensively to offset peak lactational food requirements. These and previously-reported trends suggest that ecologically comparable herbivorous marsupials and placentals utilize different physiological strategies to minimize demands on food resources during reproduction, but that both daily and overall demands can be similar.     

The effects of the platinum anti-tumour agents on renal cell kinetics and the response to a second cytotoxic agent

Abstract. Following 15 mg kg^-1 cisplatin to mice, the labelling index (LI) in the kidney decreased from 0–4% to & lt;0–01% at 1–3 d, increased to 1–9% at day 16 and returned to control levels by day 30. Cytotoxicity was assessed by counts of viable tubule cross-sections and recovery was incomplete up to 14 months after treatment.
Cisplatin treatment impaired the regeneration response to a dose of 16 mg kg^-1 uranyl nitrate (UN) given 14 d after cisplatin when assessed by an increase in LI and sub-capsular tubule count. However, there was recovery with greater time intervals. At nine months after cisplatin there was no difference in response to UN of controls and mice previously treated by cisplatin.
Prior treatment with paraplatin or iproplatin at LD₅₀ doses produced not only no histopathological changes but also no impairment of the subsequent responses to UN.     

Effect of food attractants on appetite and growth rate of gilthead bream, Sparus aurata L.

Appetite and growth rate were measured in Sparus aurata fed ad-libitum a basal diet supplemented with either a synthetic mixture of chemicals based upon the analysis of Mylilus edulis , muscle extract, or newly hatched Artemia saline nauplii. These components were tested for their feeding attraction potency, and were added to the basal diet at three concentrations each; 5, 10 and 20 g kg^-1 dry diet.
Appetite, which was defined as ad-libitum food intake, was significantly affected by the type and concentration of attractant. When the basal diet was supplemented with 10 or 20 g kg^-1 of the synthetic Mytilus edulis muscle extract, it was associated with significantly higher appetite than the basal diet only or the basal diet supplemented with any level of newly hatched Artemia salina nauplii. On the other hand, relative growth rate under the same conditions did not completely conform to the results with appetite. The difference between appetite and growth rate as criteria for the evaluation of food attractants is discussed.     

Viability of Cryptosporidium parvum during ensilage of perennial ryegrass

The survival of Cryptosporidium parvum during ensilage of perennial ryegrass was examined in laboratory silos with herbage prepared in one of three different ways; either untreated, inoculated with a strain of Lactobacillus plantarum or by direct acidification with formic acid. The pH values of all silages initially fell below 4.5, but only formic acid-treated silage remained stable at less than pH 4 after 106 d, with the pH of the untreated and inoculant-treated silages rising to above 6. The formic acid-treated silage had a high lactic acid concentration (109 g kg^-1 dry matter (DM)) and low concentrations of propionic and butyric acids after 106 d. However, the untreated and inoculant-treated silages showed an inverse relationship, with low lactic acid concentrations and high concentrations of acetic, propionic and butyric acids. These silages also contained ammonia-N concentrations in excess of 9 g kg^-1 DM. In terms of the viability of Cryptosporidium parvum oocysts very few differences were seen after 14 d of ensilage with ca 50% remaining viable, irrespective of treatment and total numbers had declined from the initial level of 5.9 × 10⁴ to 1 x 10⁴ g^-1 fresh matter. Total oocyst numbers remained approximately the same until the end of the ensiling period, with the percentage of viable oocysts declining to 46, 41 and 32% respectively for formic acid, inoculant and untreated silages. The results are discussed in terms of changes occurring during the silage fermentation, in particular the products which may influence the survival of Cryptosporidium and implications for agricultural practice and the health of silage fed livestock.     

Resting and arecoline-stimulated brain metabolism and signaling involving arachidonic acid are altered in the cyclooxygenase-2 knockout mouse

Studies were performed to determine if cyclooxygenase (COX)-2 regulates muscarinic receptor-initiated signaling involving brain phospholipase A₂ (PLA₂) activation and arachidonic acid (AA; 20 : 4n-6) release. AA incorporation coefficients, k* (brain [1–¹⁴C]AA radioactivity/integrated plasma radioactivity), representing this signaling, were measured following the intravenous injection of [1–¹⁴C]AA using quantitative autoradiography, in each of 81 brain regions in unanesthetized COX-2 knockout (COX-2^–/–) and wild-type (COX-2^+/+) mice. Mice were administered arecoline (30 mg/kg i.p.), a non-specific muscarinic receptor agonist, or saline i.p. (baseline control). At baseline, COX-2^–/– compared with COX-2^+/+ mice had widespread and significant elevations of k*. Arecoline increased k* significantly in COX-2^+/+ mice compared with saline controls in 72 of 81 brain regions, but had no significant effect on k* in any region in COX-2^–/– mice. These findings, when related to net incorporation rates of AA from brain into plasma, demonstrate enhanced baseline brain metabolic loss of AA in COX-2^–/– compared with COX-2^+/+ mice, and an absence of a normal k* response to muscarinic receptor activation. This response likely reflects selective COX-2-mediated conversion of PLA₂-released AA to prostanoids.     

Motility and fertilizing capability of cryopreserved Acipenser ruthenus L. sperm

Motility before and after cryopreservation of Acipenser ruthenus sperm was determined by computer-assisted sperm motion analysis (CASA). In addition, fertility of fresh and frozen/ thawed sperm was tested by in vitro fertilization. Sperm of A. ruthenus was successfully cryopreserved by 1/1 (v/v) dilution with ethylene glycol in final concentrations from 12.5% to 20%. Stepwise cooling using a programmable freezer and fast thawing in a water bath (40°C) for 3 s and 5 s, respectively, resulted in motility rates of 10% to 28% and fry yields of 44% to 94% compared to controls (fresh sperm). With fresh material, different sperm to egg ratios varying from 10³: 1 to 10⁶: 1 gave similar fertilization rates of more than 90%. Using this cryopreservation method the establishment of sperm banks for endangered sturgeon species and the development of a fertility test for seasonally independent testing seem to be possible.     

Growth and physiological changes during metamorphosis of Senegal sole reared in the laboratory

The metamorphosis of Solea senegalensis was studied in larvae reared at 20° C and fed four different feeding regimes. A, Artemia (4 nauplii ml⁻¹); B, Artemia (2 nauplii ml⁻¹); C, mixed diet (2 nauplii ml⁻¹ and 3 mg ml⁻¹ microencapsulated diet); and D, microencapsulated diet (3·7 mg ml⁻¹). Rotifers were also supplied in all cases during the first days of feeding. These feeding regimes supported different growth rates during the pre-metamorphosis period (regime A, G=0·376 day⁻¹; regime B, G=0·253 day⁻¹; regime C, G=0·254 day⁻¹; regime D, G=0·162 day⁻¹). Larvae started metamorphosis 9 days after hatching (DAH) when fed the regime A, 13 DAH with regime B, 11 DAH with regime C and 15 DAH with regime D. A minimum 5·6–5·9 mm L_T was required under all feeding regimes to initiate the metamorphosis. Eye translocation was completed when the larvae reached 8·6–8·7 mm L_T (regimes A, B and C), but only 7·3 mm L_T with regime D. 4·4–6·2 days were required to complete eye migration under the regimes A, B and C, and 18·3 days under the regime D. This transformation is concomitant with changes in body reserves, and with the pattern of some digestive enzymes.     

Ascorbic acid and α-tocopherol levels in larvae of Atlantic halibut before and after exogenous feeding

Ascorbic acid (AA) and α-tocopherol (α-TOH) levels in whole Atlantic halibut larvae were constant during the yolk sac stage at 170 and 131 ng individual⁻¹, respectively. At hatching c . 80% of the AA and 97% of the α-TOH were contained within the yolk-sac compartment. With development, AA and α-TOH levels in the yolk decreased, at different rates. At first feeding (at 200 day degrees post hatch, D°PH)>95% of AA but <30% of α-TOH in the yolk at hatching had been transferred to the larval body. Transfer of α-TOH was completed at 360 D°PH, when the yolk was completely absorbed. The plankton offered to the larvae at first feeding (chiefly Temora longicornis ) contained 756 μg g⁻¹ AA and 120 μg g⁻¹α-TOH (dry weight). The AA content increased to 472 ng individual⁻¹ within one week after first feeding, while it declined slightly in unfed larvae. In fed larvae the AA content reached c . 3500 ng individual⁻¹ at 580 D)PH. The α-TOH content increased only slightly in the first week of feeding (206 to 431 D°PH), but then increased to > 800 ng individual⁻¹ at 483 D°PH.     

A note on the failure of vitamin A to influence the epidermis of the brown trout, Salmo trutta L.

Three groups of hatchery–reared brown trout were fed for 32 weeks with synthetic diets containing 0, 18 and 100 i.u. vitamin A palmitate g⁻¹. Vitamin A levels in the liver of the fish at the end of the experiment were 3,50 and 300 i.u. g⁻¹ respectively. The growth rate was not significantly different between any of the three groups of fish. At all times during the investigation epidermal thickness andgoblet cell concentration were similar in the three groups but there were significant changes in goblet cell concentration within each group during the experimental period. Sexually mature males in all three groups offish contained significantly fewer epidermal goblet cells than immature fish of either sex.     

Oxygen requirements of larvae of the smallmouth bass, Micropterus dolomieui Lacépède

Smallmouth bass larvae became highly sensitive to oxygen deficiency on the second day after hatching and continued so to the 10th day. During this period they could not survive exposure to 1 mg O₂ l^–1 for 3 h at 20° C, and many were killed within 1 h. At 2 mg O₂ l^–1 half the larvae survived 3 h at 20° C; at 2.5 mg l^–1 most survived, and at 3.5 mg l^–1 all survived. Resistance to oxygen deficiency was regained by the 11th day, the majority of the larvae withstanding a 3-h exposure at 1 mg O₂ l^–1. At 25° C the effects of low oxygen concentration were intensified. At 3 and 4 mg O₂ l^–1 and 20° C the normally quiescent larvae became very active, even swimming to the surface 5 or 6 cm above the substrate. Increasing the temperature increased this response. Smallmouth larvae were more sensitive than large-mouth bass larvae to oxygen deficiency.