37,063 research outputs found
Cryopreservation of Pike Perch Sperm in Hatchery Conditions
No full textExperiments were carried out on pike perch (Sander lucioperca L.) to find a method for stripping
sperm without contamination by urine, to determine sperm concentration, and to fertilize large
batches of eggs with cryopreserved sperm. Induced spawning technology for pike perch, an
important predator fish species in Hungarian and central-eastern European pond aquaculture,
has been developed only recently. Sperm cryopreservation can be an important tool for several
reasons including the simplification of hatchery work and long-term preservation of genomes of
males with high genetic value. In the present study, sperm was stripped without urine contamination,
improving sperm quality, and large amounts of eggs were fertilized using 0.25 ml sperm,
resulting in hatching percentages of 55±3% for 30-g batches of eggs and 87% for a 50-g batch
Intraspecific variation in the metabolism of juvenile Atlantic salmon salmo salar and northern pike esox lucius
No full textBasal metabolic rate (BMR), the sum of maintenance energy costs, represents a major component of the energy budgets of ectothermic vertebrates and varies between individuals within a species. Individual ectotherms are generally assumed to have a constant BMR at any given temperature. A strategy of flexibility in BMR might have evolved to cope with differing environmental conditions. Within-individual variation in BMR was examined in two fishes, juvenile Atlantic salmon Salmo salar and juvenile northern pike Esox lucius, whilst the effects of exercise and ration on BMR, maximum metabolic rate (MMR), enzyme levels and body composition were studied in detail for pike. In the first part of the study, measurements of BMR were made for first-summer Atlantic salmon parr at rest by respirometry. In 1996, initial measurements of BMR were made for 25 fish held in a stock tank. Fish were then allocated in small groups to channels to represent a change in environment and BMR re-measured after a period of several weeks. The procedure was repeated for 30 fish in the summer of 1997, when fish were given a reduced food ration. Variation in BMR in each experiment was analysed for individual fish, and for all fish using a linear mixed model. There were statistically significant differences in BMR values between the two times, the within-individual, between-time variation representing approximately ± 21% of BMR in 1996 and ± 28% of BMR in 1997. Reduced-rafion fish (1997) displayed a significant decrease in the mean elevation of the allometric scaling relationship between body mass and BMR between time periods. To further explore possible mechanisms for flexibility in BMR and relationships with MMR, juvenile pike were used. Initial measurements of BMR and MMR (following exhaustive exercise) were made and factorial metabolic scope calculated (MMR/BMR). Fish were then split into a high ration no-exercise group (n = 10), low ration no-exercise group (n = 10) and sustained exercise group (n = 13). Initial measurements were termed time 1, with subsequent measurements made after approximately 3 weeks (time 2) and 11 weeks (time 3). Exercised fish had a significantly larger MMR and scope following 3 weeks of sustained swimming. For all fish there were significant correlations between BMR and MMR at times 1 and 3 but not at time 2.After the oxygen measurements made at time 3 all fish were humanely killed. Maximal enzyme assays were performed on six tissues for each remaining fish (n = 30). Levels of each of two enzymes (citrate synthase, CS, and lactate dehydrogenase, LDH, measured in the direction of lactate oxidation) were found to be similar between treatment groups for respective tissues. Total CS activity levels and LDH levels were highest in the heart and red muscle. In general there was little difference in the relative organ masses of fish exposed to different treatments. It is concluded that in these two fish species with very different life styles, between- and within- individual variation in BMR (salmon & pike) and MMR (pike only) is apparent and that differences in ration and exercise influence individual physiology
Moore, B. G.
No full textSee entry in Pike County, volume 1, page 17: https://digital.archives.alabama.gov/digital/collection/voter1867/id/414
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Comparison of Growth in Pike-Perch (Sander lucioperca) and Hybrids of Pike-Perch (S. lucioperca) × Volga Pike-Perch (S. volgensis)
No full textGrowth of intensively cultured pike-perch Sander lucioperca (L.) and hybrids of pike-perch females × Volga pike-perch (S. volgensis Gmelin, 1789) males (1.75 g) were compared in a 35-day experiment. Fish were sorted into three groups (50 fish/aquarium): S. lucioperca grown separately (Group P), hybrids grown separately (Group H), and a mixed group of 25 S. lucioperca (Group Mp) grown together with 25 hybrids (Group Mh). The stocking density was 0.44 g/l. Final body weights were 6.83 g, 6.54 g, 5.17 g, and 4.84 g, and specific growth rates were 3.9%/day, 3.75%/day, 3.1%/day, and 2.89%/day, for groups Mp, P, Mh, and H, respectively. The weight, length, and specific growth rates of the S. lucioperca were significantly higher (p<0.05) than those of the hybrids, whether grown separately or together. The feed conversion rate of the hybrids grown separately was significantly higher (1.28 g/g) than all other groups. Further investigation is needed to study the growth performance of larger hybrids, to compare the hybrid with S. volgensis, and to investigate the possibility of cross hybridization
Techniques for Evaluating the Spatial Behaviour of River-Fish
No full textRadio-tagging is widely used for studies of movements, resource use and demography of land vertebrates, with potential to combine such data for predictive modelling of populations from individuals. Such modelling requires standard measures of individual space use, for combination with data on resources, survival, dispersal and breeding. This paper describes how protocols for efficient collection of space-use data can be developed during a pilot study, and reviews the ways in which such data can be used for space-use indices that help answer biological questions, with examples from a study of riverine pike (Esox lucius). Analyses of diurnal activity and spatio-temporal correlation were used to assess when to record locations, and analyses of home range increments were used to define the number of location records necessary to assess seasonal ranges. We stress the importance of developing protocols that use minimal numbers of locations from each individual, so that analyses can be based on samples of many individuals. The efficacy of link-distance (e.g. cluster analysis) and location density (e.g. contouring) techniques for spatial analysis for river fish were compared, and the utility of clipping off areas to river banks was assessed. In addition, a new automated analysis was used to estimate distances along river mid-lines. These techniques made it possible to quantify interactions between individuals and their habitat: including a significant increase in core range size during floods, significant preference for deep pools, and a lack of exclusive territories
545, 7 pages Comparison of Growth in Pike-Perch (Sander lucioperca) and Hybrids of Pike-Perch (S. lucioperca) × Volga Pike-Perch
No full textAbstract Growth of intensively cultured pike-perch Sander lucioperca (L.) and hybrids of pike-perch females × Volga pike-perch (S. volgensis Gmelin, 1789) males (1.75 g) were compared in a 35-day experiment. Fish were sorted into three groups (50 fish/aquarium): S. lucioperca grown separately (Group P), hybrids grown separately (Group H), and a mixed group of 25 S. lucioperca (Group Mp) grown together with 25 hybrids (Group Mh). The stocking density was 0.44 g/l. Final body weights were 6.83 g, 6.54 g, 5.17 g, and 4.84 g, and specific growth rates were 3.9%/day, 3.75%/day, 3.1%/day, and 2.89%/day, for groups Mp, P, Mh, and H, respectively. The weight, length, and specific growth rates of the S. lucioperca were significantly higher (p<0.05) than those of the hybrids, whether grown separately or together. The feed conversion rate of the hybrids grown separately was significantly higher (1.28 g/g) than all other groups. Further investigation is needed to study the growth performance of larger hybrids, to compare the hybrid with S. volgensis, and to investigate the possibility of cross hybridization
THE TRANSITION OF MOLECULAR OXYGEN
No full textAuthor Institution: Research School of Physical Sciences and Engineering, The Australian National University; Molecular Physics Laboratory, SRI InternationalThe origin of the intensity of the transition of molecular oxygen, first observed recently by Eppink et al. [J. Chem. Phys. 108, 1305 (1998).], is discussed. It is shown that the transition borrows its intensity principally from the dipole-allowed transition, through spin-orbit mixing between the and states. Estimated continuum photoabsorption cross sections and discrete oscillator strengths for the system are presented
Observations of Bºs→ψ(2S)η and Bº(s)→ψ(2S)π+π- decays
No full textFirst observations of the B0s
→ψ(2S)η, B0 →ψ(2S)π
+
π
− and B0s
→ψ(2S)π
+
π
− decays are made
using a dataset corresponding to an integrated luminosity of 1.0 fb−1 collected by the LHCb experiment in
proton–proton collisions at a centre-of-mass energy of
√
s = 7 TeV. The ratios of the branching fractions
of each of the ψ(2S) modes with respect to the corresponding J/ψ decays are
B(B0s
→ψ(2S)η)
÷
B(B0s
→J/ψη)
= 0.83± 0.14 (stat)±0.12 (syst) ±0.02 (B),
;
B(B0→ψ(2S)π
+
π
−
)
÷
B(B0→J/ψπ
+
π
−
)
= 0.56± 0.07 (stat)±0.05 (syst)± 0.01 (B),
;
B(B0s
→ψ(2S)π
+
π
−
)
÷
B(B0s
→J/ψπ
+
π
−
)
= 0.34± 0.04 (stat)±0.03 (syst)± 0.01 (B),
where the third uncertainty corresponds to the uncertainties of the dilepton branching fractions of the J/ψ
and ψ(2S) meson decays
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