ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    The early growth of artificially reared American lobsters (1981)
    Springer
    Theoretical and applied genetics 60 (1981), S. 269-273 
    Details
    ISSN: 1432-2242
    Keywords: Genetic parameters ; Early growth ; Lobsters ; Muliple-environment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Twenty families of the lobster, Homarus americanus, were reared at 10°, 15° and 20°C with and without bilateral eye-stalk-ablation. At 20°C both eye-stalk-ablated and non-eye-stalk-ablated lobsters from each family were assigned to one of two dietary treatments: 1) frozen whole brine shrimp, or 2) a diet of cheap, local constituents. The means of growth traits improved while viability decreased with increasing temperature. The ablation technique shows promise since improved performance for growth was apparent in eye-stalk ablated lobsters, but mortality was greater. Important genetic variation of all traits was found in each of the environments tested. The genetic correlations between growth traits were reinforcing, but the correlations between growth and viability traits were mainly negative. Ease and reliability of measurement should be considered when choosing growth traits in any artifical selection program.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00263715
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    The effect of simultaneous selection on the genetic correlation (1995)
    Springer
    Theoretical and applied genetics 91 (1995), S. 776-779 
    Details
    ISSN: 1432-2242
    Keywords: Index selection ; Genetic correlation ; Simulation ; Heritability ; Economic weight
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The theoretical effect of simultaneous selection on the genetic correlations between two traits over 20 generations was examined using simulation. For each generation, a population of 50 male and 50 female diploid gen otypes with 15 loci, each with two alleles, was synthesized. None of the loci exhibited dominance. Five loci affected only trait 1, 5 loci only trait 2 and 5 were pleiotropic (affected both traits). Initial allelic frequencies were equal at each locus. Phenotypes were created by adding a random normal deviation for each trait to the genotype. The size of this deviation for each trait determined its heritability (h2). Index selection with h2 combinations of (0.15, 0.15), (0.15,0.45) and (0.45,0.45) and relative economic weights of (1, 1) and (1, 3) for each h2 combination was employed. In each generation, the highest ranking 25 genotypes of each sex were used to generate the next generation with single-pair matings, each producing two male and two female offspring. One hundred replicates were run for both negative and positive correlations. With a positive initial value, the genetic correlation tended to decline (toward zero). The rates of change were moderately affected by index weights and h2. With a negative initial value, the genetic correlation tended to decrease (towards -1). However, unequal heritabilities and unequal relative economic weights slowed the rate of change with the greatest imbalances tending to hold the correlation constant or move it toward zero. These simulations illustrate that changes in parameters over time can affect the selection practiced. Under some of the conditions simulated, the use of initial genetic parameter values without change could have potentially negative effects on overall genetic gain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00220958
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Age changes in genetic and environmental variation in laying hens (1984)
    Springer
    Theoretical and applied genetics 67 (1984), S. 391-401 
    Details
    ISSN: 1432-2242
    Keywords: Age changes ; Egg production and quality ; Genetic and environmental factors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Effects of age on the genetic and environmental variation of egg production, egg weight and egg quality were investigated in two populations of laying hens. The first part of the study was based on data from a crossbred population in Sweden that allowed the estimation of sire and residual but not of dam variance components. Sire, dam and residual components of variance were estimated in the second part of the study that used data from eight generations of two unselected control and four high egg production-selected Canadian strains of chickens. — Although the data did not allow a clear-cut separation of the various genetic and environmental variance components, the results indicated that new genetic variation appeared parallel to an increase in the environmental variation with age of the birds. This was interpreted as a suggestion that the deteriorating process of aging impaired the organism's ability to cope with environmental conditions and this resulted in the observed increase in environmental variation. The simultaneous increase of the genetic variation was caused by the turning on of new genes in order to induce reactions counteracting the effects of aging. Alternatively, reduced accuracy of DNA transcription in older birds may cause impairment of the functional efficiency of metabolic systems thus increasing environmental variation parallell to an increase of genetic “error variation”.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00263399
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    An empirical comparison of selection methods for the improvement of biomass (1977)
    Springer
    Theoretical and applied genetics 50 (1977), S. 193-198 
    Details
    ISSN: 1432-2242
    Keywords: Selection ; Pupal Weight ; Biomass ; Tribolium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A single generation of upward truncation selection on families with 20% selected was carried out in each of five replicates using Tribolium castaneum as the test organism. The experiment involved eight lines: N — selected for offspring number; W — selected for pupal weight; B — selected for biomass; Q — quadratic index selected; L21 — linear index selected with relative economic weights of 2∶1 offspring number to pupal weight; L11 — linear index selected with relative economic weights of 1∶1 offspring number to pupal weight; L12 — linear index selected with relative economic weights of 1∶2 offspring number to pupal weight; C — an unselected control. Biomass (weight of offspring per family), offspring number, and pupal weight were measured. No differences in response to selection were found among the linear index lines and the pupal weight line with regard to any trait analysed. Generally, response to selection in the linear index lines and pupal weight line was small for offspring number and high for pupal weight. Selection pressure on offspring number in these lines seemed to be dependent on the correlation between offspring number and pupal weight. As a result, response to selection for biomass was poor in the linear index and pupal weight selected lines. In the case of the linear indices, poor response to selection for biomass appeared to be due to the violation of the assumption of additivity of the traits included in the definition of aggregate genotype. The responses in the quadratic index, biomass, and offspring number selected lines were equal with respect to selection for biomass. The response of the quadratic index selected line was less than the responses of the biomass and offspring number selected lines for offspring number, but the response in the quadratic index line was as large as that of any other line included in the experiment and greater than the biomass and offspring number selected lines where pupal weight was the criterion. Highly significant amounts of variation were found for all traits indicating that more replicates are needed for precise evaluation of selection systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00277741
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    The effect of warming velocity on motility and acrosomal integrity of boar sperm as influenced by the rate of freezing and glycerol level (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 34 (1993), S. 190-195 
    Details
    ISSN: 1040-452X
    Keywords: Thawing velocity ; Freezing rate ; Glycerol concentration ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The effect of thawing velocities ranging from 10°C/min to 1.800°C/min on the motility and acrosomal integrity of boar spermatozoa frozen at 1°C/min (suboptimal), 5°C/min, and 30°C/min (optimal) rate was studied with the sperm suspended for freezing in diluent containing 2, 4, or 6% of glycerol (v/v). The influence of thawing on sperm survival depends on the rate at which the sperm had been frozen. In semen frozen at a suboptimal rate of 1°C/min, the percentage of motile sperm (FMP) initially fell to 3.5-4.0% when the thawing rose to 200°C/ min, but, with further increases in thawing rate, increased and reached peak values (10.3-11.0% FMP) after thawing at 1,800°C/min. The percentage of sperm with normal apical ridge (NAR) also increased moderately with thawing rate, but the degree of improvement decreased as the glycerol level was increased. In semen frozen at 1°C/min, acrosomal integrity (NAR) was best maintained in 2% glycerol, reaching 22.9% NAR after thawing at 1,800°C/min. In semen frozen at the optimal rate of 30°C/min, the increases in thawing rates above 200°C/min substantially improved motility. Motility was generally higher in semen protected by 4 or 6% glycerol, with the peak values of 44 or 46% FMP, respectively, after thawing at 1,200°C/min. The proportion of sperm with NAR also increased with thawing rate, but as in the case of suboptimally frozen sperm it was influenced negatively by the glycerol concentration. The peak value 53% NAR was recorded in semen protected by 2% glycerol, frozen at 30°C/min, and thawed at 1,200°C/min. In view of the inverse relationship between FMP and NAR, selection of optimal conditions from among the interacting variables, freezing rate, glycerol concentration, and thawing rate requires compromising between maximal FMP and maximal NAR. Accordingly, we have adopted as optimal a protocol with a thawing rate of 1,200°C/min, a freezing rate of 30°C/min and concentrations of 3% glycerol. © 1993 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080340211
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Combined effect of glycerol concentration and cooling velocity on motility and acrosomal integrity of boar spermatozoa frozen in 0.5 ml straws (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 25 (1990), S. 123-129 
    Details
    ISSN: 1040-452X
    Keywords: Porcine semen ; Freezing rate ; Cryoprotectant level ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The interaction of glycerol concentrations of 0-10% and cooling rates from 1 to 1,500°C/min with boar spermatozoa motility and acrosomal integrity (proportion of spermatozoa with normal apical ridge) was studied after thawing 0.5 ml straws at a constant rate. While increasing the glycerol concentration from 0 to 4% progressively improved motility, the percentage of spermatozoa with a normal apical ridge gradually decreased. The magnitudes of the respective changes depended on cooling rate. A peak value of 48.1% and rating 3.8 were obtained in semen protected with 4% glycerol, frozen at 30°C/min. Increasing the glycerol levels above 6% resulted in a gradual decrease in motility. The proportion of spermatozoa with normal apical ridge was highest in semen protected with 0-1% glycerol after cooling at 30°C/min (64.4% and 66.1%, respectively), but at these glycerol concentrations the percentage of motile spermatozoa was low. At the 30°C/min cooling rate, the decline in the proportion of cells with normal apical ridge due to increasing the glycerol levels to 3 and 4% was relatively slow (57.3% and 49.4%, respectively). Cooling at 1°C/min was detrimental to acrosomal integrity, which decreased with increasing glycerol concentration, in contrast to increasing motility, which even at its maximum, remained low. The direct plunging of straws into liquid nitrogen (1,500°C/min) resulted in damaged acrosomes in all spermatozoa with the total loss of motility. Balancing motility and acrosomal integrity, freezing boar semen protected with 3% glycerol by cooling at 30°C/min resulted in optimal survival for boar semen frozen in 0.5 ml French straws.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080250204
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...