ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1995.tb06018.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

An infra‐red video recording system was used to observe and compare the feeding activity of juvenile sole and plaice. Experiments in light or dark and chemical ablation of the neuromasts with streptomycin sulphate allowed all or a limited set of senses to be used by the fishes. Both species were able to feed on dead prey when only chemical stimuli were available. Plaice showed a greater dependence on vision for feeding but sole relied principally on chemoreception and mechanoreception. When any one sense was removed plaice became less active whereas sole became more activ

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1995.tb06019.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Concentrations of calcium, strontium, sodium, and potassium were measured along chronological transects of sectioned sagittae from adult red drum (Sciaenops ocellatus), using a wavelength‐dispersive electron microprobe. Coarse sampling involved triplicate measurements at the centre of each opaque (winter) and translucent (summer) zone. Fine sampling was performed in duplicate at equidistant points (15 μm apart) spanning four opaque zones (3 years of life). Concentrations of strontium generally increased with distance from the core (age). Other elements showed no consistent long‐term trends. Sodium and potassium showed consistent differences between winter and summer otolith zones for ages 6 to 15, but calcium and strontium did not show this seasonal difference. Sampling through these zones on a finer spatial scale confirmed the winter/summer differences as cyclic trends. There was general concordance between annual variation in sodium and potassium concentrations in otoliths and concurrent trends in sea temperature, but significant departures in agreement suggested that temperature was not the immediate determinant of sodium and potassium incorporation. It is suggested that the roughly seasonal patterns of variation in otolith sodium and potassium concentrations may be a result of reproductive acti

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1995.tb06020.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Relationships among the less derived genera in the subfamily Salmoninae were investigated by phylogenetic analysis of data from restriction maps of the ribosomal DNA usingOsmerus mordax(rainbow smelt),Coregonus hoyi(bloater), andThymattus arcticus(Arctic grayling) as outgroups. Analysis of the results suggests thatHucho h. taimenis more closely related toBrachymystax lenok(lenok) than toHucho perryi(Sakhalin taimen) and thatB. lenokandHucho h. taimen(Eurasian taimen) form the most ancestral clade of the Salmoninae.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1995.tb06021.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

East coast geelbek exist as a single stock comprising three distinct age/size structured subpopulations. The subadults (1‐4 years) occur in the SW Cape, South Africa. They feed principally on anchovyEngraulis capensis, which they follow inshore in summer and offshore in winter. The adults (5‐9+ years) undergo a seasonal inshore and longshore migration to Natal where they spawn offshore in spring. During this migration they feed mainly on the pilchardSardinops sagax, which also move north‐eastwards during this time, facilitated by regional oceanographic conditions. ‘Adolescent’ fish (4/5 years) appear to undergo limited gonadal growth and partially accompany the spawning stock on their migration. It is suggested that the eggs, larvae and early juveniles are transported southwards by the peripheral inshore waters of the Agulhas Current. Juveniles (<2 years) use the SE Cape region as a nursery area for about 1 year, initially feeding on mysids and then switching to anchovy, before moving south‐westwards to join the Subadults in the SW

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1995.tb06022.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Computer‐assisted semen analysis (CASA) technology was applied to the measurement of sperm motility parameters in the common carpCyprinus carpio.Activated sperm were videotaped at 200 frames s−1and analysed with the CellTrak/S CASA research system. The percentage of motile cells and both sperm head curvilinear velocity and straight‐line velocity were measured following exposure of carp sperm to three predilution conditions and activation in media of differing ionic strengths and osmotic pressures. The highest percentage of motile sperm was obtained following predilution of sperm in seminal plasma and activation in Na‐HEPES buffer pH 8.0. This level of motility was equalled after predilution in 200 mmKCl for 2 h. Straight‐line velocities and curvilinear velocities of 130 μm s−1and 210 μm s−1, respectively, were observed. Duration of motility was higher under seminal plasma predilution conditions (over 50% motile sperm at 55 s post‐activation). The application provides a sound basis for the assessment of Sperm Charac

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1995.tb06023.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Adult golden perchMacquaria ambiguawere fed to satiety, starved for up to 210 days, or starved for 150 days then fed to satiety for 60 days to investigate the utilization of energy stores in response to food deprivation and re‐feeding. Golden perch sequentially mobilize energy from hepatic tissue, extra‐hepatic lipid, and finally muscle components in response to food deprivation. The relative size of the liver was significantly reduced by 30 days after the onset of food deprivation due to the simultaneous mobilization of lipid, protein and glycogen reserves. These stores were renewed rapidly within 30 days by satiety feeding. Mobilization of lipid stores in perivisceral fat bodies occurred between 30 and 60 days of food deprivation. These deposits were also renewed upon re‐feeding, although not as rapidly as liver reserves. The glycogen content of the epaxial muscle was reduced by the 60th day of food deprivation but subsequently increased indicating the mobilization of other energy reserves. The concentration of muscle lipid decreased after 90 days of food deprivation. The only significant response in body composition observed in the fish fed to satiety throughout the study was an increase in the relative size of the perivisceral fat bodies. The results of this study suggest that golden perch are well adapted to cope with extended periods of food deprivation, storing energy as perivisceral fat when food is readily available and having a clearly sequential process for mobilizing energy when food is scarce which largely protects the integrity of the muscul

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1995.tb06024.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Channel catfish leucocytes cryopreserved with glycerol or dimethyl sulphoxide (DMSO) had significantly higher (P<0.05) viability and recovery rates than did cells cryopreserved with methanol. After 7 days of frozen storage, a 24 to 27% reduction of viability was observed for cells cryopreserved with glycerol; a 25 to 43% reduction for cells frozen with DMSO, and a 67 to 100% reduction for cells frozen with methanol. The concentration of cryoprotectants affected the viability of cryopreserved cells significantly (p<0.05). The viability reduction was 36% for cells frozen with 5% of cryoprotectants, 30% for cells frozen with 10% of cryoprotectants, and 49% for cells frozen with 15% of cryoprotectants. The viability of cells frozen at the slower rate (‐2.7°C min−1) was significantly higher (p<0.05) than that of cells frozen at the faster rate (‐45°C min−1). Best results were obtained for cells cryopreserved with 10% of glycerol or DMSO and frozen at the slower rate. The chromosomes prepared from cells cryopreserved using this procedure were identical to those prepared from fresh cells, and to those reported in the literature for channe

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1995.tb06025.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

The distribution and ultrastructure of myotomal muscle fibres was studied in larvae and early juveniles of the curimatã‐pacúProchilodus marggravii, a tropical freshwater fish endemic to the São Francisco River system, Brazil. At 26°C, larvae hatched 15 h post‐fertilization at a relatively early stage of development with the head still curved around the yolk‐sac (head‐trunk angle greater than 45°), and prior to pigmentation of the eyes and formation of the jaws, gut and pectoral fins. Although motile the swimming muscles of newly‐hatched larvae were largely undifferentiated. The myotomes were made up of a single layer of superficial muscle fibres containing six to eight myofibrils and abundant mitochondria, surrounding an inner core of myoblasts, myotubes and immature muscle fibres. The volume densities of mitochondria and myofibrils in the immature inner muscle fibres of 1‐day‐old lavae were 14.5 and 6.4% respectively. The body axis straightened within 24 h of hatching and the yolk sac was completely absorbed by 72 h. Larval development was rapid with gill filaments, a muscular stomach, liver and swimbladder present after 7 days. The inner muscle fibres were well differentiated in 7‐day‐old larvae; the volume density of myofibrils had increased to 63.1% whereas the volume density of mitochondria had decreased to 3.5%. In 14‐day‐old juveniles the superficial muscle had thickened to a layer two to three fibres thick in the region of the lateral line nerve and capillaries were present in the inner muscle. Muscle growth until 14 days was largely due to the hypertrophy of the

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1995.tb06026.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Three sympatric morphs of Arctic charrSalvelinus alpinusoccur in Loch Rannoch, Scotland, and are identified by their differing head morphology and diet. These are small‐headed benthic, large‐headed benthic and pelagic morphs. Six species of endoparasitic helminth were found in the fish, but the morphs had different patterns of infection. Overall infections in pelagic charr were heavier than in large‐headed benthics, which were in turn heavier than in small‐headed benthics, even though benthic charr live longer than pelagics. Pelagic fish had high prevalences and intensities of pseudophyllidean tapeworms, the intermediate hosts of which are copepods. The prevalence and intensity of metacercariae ofDiplostomumsp. (the intermediate hosts of which are snails) were high in the benthic morphs. The results are discussed in terms of the effects of ecological factors on transmission of helminth parasites to their hosts and the evolution of host‐parasite ass

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1995.tb06027.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY