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  • Springer  (254)
  • MDPI Publishing
  • Mineralogical Society of Great Britain and Ireland
  • 1
    Electronic Resource
    Electronic Resource
    Relative absorption of the two enantiomers of terbutaline after duodenal administration (1990)
    Springer
    European journal of clinical pharmacology 38 (1990), S. 621-623 
    Details
    ISSN: 1432-1041
    Keywords: terbutaline ; absorption ; enantiomers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The absorption of the two enantiomers of terbutaline, (+)-terbutaline and (-)-terbutaline, and of the racemate, (±)-terbutaline, has been studied in six healthy volunteers using a newly developed intestinal perfusion technique. The area under the plasma concentration curve for the (-)-enantiomer was more than twice that for the (+)-enantiomer. The data demonstrate a clear difference in absorption efficiency between (-)- and (+)-terbutaline, but further studies are required to establish whether (-)-terbutaline influences the absorption of (+)-terbutaline.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00278593
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  • 2
    Electronic Resource
    Electronic Resource
    Desoxypatulinic acid from a patulin-producing strain ofPenicillium patulum (1972)
    Springer
    Cellular and molecular life sciences 28 (1972), S. 1252-1252 
    Details
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Zusammenfassung Aus Kulturlösungen vonPenicillium patulum Bainier wurde neben Patulin die Desoxypatulinsäure isoliert und identifiziert.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01946206
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  • 3
    Electronic Resource
    Electronic Resource
    The ultrastructure of the spiral notosetae ofNicomache maculata Arwidsson (Polychaeta, Maldanidae) (1978)
    Springer
    Cellular and molecular life sciences 34 (1978), S. 460-462 
    Details
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Scanning- and transmission electron microscopy show that the long, thin notosetae ofNicomache maculata are helical over much of their length, and that their finely feathered appearance is produced by a series of minutely spiny scales. The internal structure varies considerably from one end of the seta to the other. While a helical shape could result from a rotating or asymmetrical secretion-rate gradient across the chaetoblast, we raise the possibility that the spiral represents a warp in the seta following deposition of the setal material.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01935926
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  • 4
    Electronic Resource
    Electronic Resource
    The use of the relationship matrix to account for genetic drift variance in the analysis of genetic experiments (1983)
    Springer
    Theoretical and applied genetics 66 (1983), S. 217-220 
    Details
    ISSN: 1432-2242
    Keywords: Response to selection ; Genetic drift ; Relationship matrix
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Selection experiments can provide information on genetic parameters such as realized heritability and response to selection. Often, due to lack of adequate replication, empirical sampling variances of estimated response cannot be computed and therefore use must be made of theoretical formulae. Most of the variance between a conceptually large number of selected lines drawn from the same base population is contributed by genetic drift, which depends on the population structure and can therefore be predicted before the experiment is carried out. The theory of variation of response to selection has been developed mainly by Hill, who produced formulae to adjust the variance of estimators to take account of genetic drift. In this paper, we draw attention to properties of the additive genetic relationship matrix that lead to well established results in population genetics theory. We show how inclusion of the additive genetic relationship matrix among the observations leads to sampling variances of estimators of genetic means that account for the variance due to genetic drift.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00251147
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  • 5
    Electronic Resource
    Electronic Resource
    Index versus tandem selection after repeated generations of selection (1993)
    Springer
    Theoretical and applied genetics 85 (1993), S. 706-712 
    Details
    ISSN: 1432-2242
    Keywords: Selection index ; Tandem selection ; Multiple selection ; Linkage disequilibrium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A theoretical comparison between two multiple-trait selection methods, index and tandem selection, after several generations of selection was carried out. An infinite number of loci determining the traits, directional and truncation selection, discrete generations and infinite population size were assumed. Under these assumptions, changes in genetic parameters over generations are due to linkage disequilibrium generated by selection. Changes continue for several generations until equilibrium is approached. Algebraic expressions for asymptotic responses from index selection can be derived if index weights are maintained constant across generations. Expressions at equilibrium for genetic parameters and responses are given for the index and its component traits. The loss in response by using initial index weights throughout all generations, instead of updating them to account for changes in genetic parameters, was analyzed. The benefit of using optimum weights was very small ranging from 0% to about 1.5% for all cases studied. Recurrence formulae to predict genetic parameters and responses at each generation of selection are given for both index and tandem selection. A comparison between expected response in the aggregate genotype at equilibrium from index and tandem selection is made considering two traits of economic importance. The results indicate that although index selection is more efficient for improving the aggregate breeding value, its relative efficiency with respect to tandem selection decreases after repeated cycles of selection. The reduction in relative efficiency is highest with the highest selection intensity and heritabilities and with negative correlations between the two traits. The advantage of index over tandem selection might be further reduced if changes in genetic parameters due to gene frequency changes produced by selection, random fluctuations due to the finite size of the population, and errors in estimation of parameters, were also considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00225009
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  • 6
    Electronic Resource
    Electronic Resource
    Potential bias in inbreeding depression estimates when using pedigree relationships to assess the degree of homozygosity for loci under selection (1995)
    Springer
    Theoretical and applied genetics 91 (1995), S. 665-671 
    Details
    ISSN: 1432-2242
    Keywords: Inbreeding ; Finite-locus model ; Selection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A potential bias in estimation of inbreeding depression when using pedigree relationships to assess the degree of homozygosity for loci under selection is indicated. A comparison of inbreeding coefficients based on either pedigree or genotypic frequencies indicated that, as a result of selection, the inbreeding coefficient based on pedigree might not correspond with the random drift of allelic frequencies. Apparent differences in average levels of both inbreeding coefficients were obtained depending on the genetic model (additive versus dominance, initial allelic frequencies, heritability) and the selection system assumed (no versus mass selection). In the absence of selection, allelic frequencies within a small population change over generations due to random drift, and the pedigree-based inbreeding coefficient gives a proper assessment of the accompanying probability of increased homozygosity within a ‘replicate’ by indicating the variance of allelic frequencies over replicates. With selection, in addition to random drift, directional change in allelic frequencies is not accounted for by the pedigree-based inbreeding coefficient. This result implies that estimation of inbreeding depression for traits under either direct or indirect selection, estimated by a regression of performance on pedigree-based coefficients, should be carefully interpreted.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00223295
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  • 7
    Electronic Resource
    Electronic Resource
    The effect of positive assortative mating on genetic parameters in a simulated beef cattle population (1986)
    Springer
    Theoretical and applied genetics 72 (1986), S. 76-79 
    Details
    ISSN: 1432-2242
    Keywords: Simulation ; Positive assortative mating ; Beef cattle population
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Two simulated data sets, representing random mating and positive assortative mating in a beef cattle population over 10 rounds of mating, were each composed of 100 replicates. Three correlated traits were considered; calving ease (CE), 200 day weight (WW) and postweaning gain (PG). All selection practiced in the simulation was random. Positive assortative mating, which was based on parental WW phenotypic records, increased the progeny additive genetic variance of WW. The absolute values of genetic covariances and correlations between WW with CE and PG were also increased by positive assortative mating. Variances or covariances did not reach their expected equilibrium values due to overlapping generations, low replacement rates and only 10 rounds of mating.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00261458
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  • 8
    Electronic Resource
    Electronic Resource
    Efficiency of indirect selection at selection equilibrium (1991)
    Springer
    Theoretical and applied genetics 81 (1991), S. 166-172 
    Details
    ISSN: 1432-2242
    Keywords: Indirect selection ; Correlated response ; Linkage disequilibrium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Efficiency of indirect selection compared with that of direct selection to increase the mean value of some trait has been usually studied by considering a single generation of indirect and direct responses to selection only. However, under continued selection, genetic variances and covariances, and therefore expected genetic responses, change each generation due to linkage disequilibrium. With directional and truncation selection, genetic parameters asymptote to limiting values after several generations. The efficiency of indirect selection is examined in this limiting situation. The ratio of correlated response to direct response for the trait to improve in the limit is compared with the ratio after the first generation of selection. For all initial parameter values for which indirect selection is more efficient than direct selection, relative efficiency of indirect selection is smaller in the limit than in the first generation. For some parameter values, indirect selection is more efficient than direct selection in the first generation, but less efficient in the limit. Expressions for minimum values of the initial genetic correlation and heritability of the alternative trait required for indirect selection to be preferred in the limit are derived. These values are higher when limiting responses are used instead of single generation responses. The loss in relative efficiency of indirect selection from changes in genetic parameters due to selection should be taken into account when applications of indirect selection are considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00215719
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  • 9
    Electronic Resource
    Electronic Resource
    The use of constrained selection indexes in breeding for economic merit (1990)
    Springer
    Theoretical and applied genetics 80 (1990), S. 801-805 
    Details
    ISSN: 1432-2242
    Keywords: Economic weights ; Restricted indexes ; Desired gains
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Various methods exist for the derivation of restricted and/or desired gains selection indexes, and their use in applied breeding has been advocated. It is shown that there exists a set of implied linear economic weights for all constrained indexes and their derivation is given. Where economic weights are linear and known, a standard selection index is, by definition, optimal and thus a constrained index will usually be suboptimal. It is argued that economic weights can always be estimated and that the effects of uncertain weights can be examined by sensitivity analysis. If economic weights are nonlinear, use of the first order (linear) economic weights or a derived linear index, using previously described methods, will give very close to optimum economic selection responses. Examples from the literature indicate that severe losses of potential economic gain can possibly occur through use of a constrained index. It is concluded that constrained indexes should be avoided for economic genetic selection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00224195
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  • 10
    Electronic Resource
    Electronic Resource
    Method to estimate genotype probabilities at individual loci in farm livestock (1989)
    Springer
    Theoretical and applied genetics 78 (1989), S. 735-740 
    Details
    ISSN: 1432-2242
    Keywords: Individual loci ; Estimation ; Genetic counseling ; Genotype probabilities ; Accuracy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A Bayesian method to estimate genotype probabilities at a single locus using information on the individual and all its relatives and their mates has been developed. The method uses data over several generations, can deal with large numbers of individuals in large livestock families and allows for missing information. It can be extended to multiple alleles and can be used for autosomal or sex-linked loci. The allele frequencies and the form of expression (dominance, penetrance) must be specified. An algorithm using the method and involving an iterative procedure has been developed to calculate the genotype probabilities for practical use in livestock breeding. The method and algorithm were used to determine the accuracy of estimating genotype probabilities of sires for a female sex-limited trait, such as genetic variants of milk proteins. Data were similated and genotype probabilities estimated for 100 sires (20 replicates) with 3, 6 and 12 female offspring per sire, for different population frequencies, for additive and dominance gene action and for variable genotypic expression. Such simulation is useful in the design of testing systems for the use of information on specific genetic loci in selection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00262571
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