scholarly journals Optimum selection strategies: studies with Drosophila melanogaster

1985 ◽  
Vol 46 (1) ◽  
pp. 101-105
Author(s):  
Aurora García-Dorado ◽  
Carlos López-Fanjul
Keyword(s):  
Drosophila Melanogaster ◽  
Theoretical Treatment ◽  
Good Qualitative Agreement ◽  
Selected Lines ◽  
Selection Strategies ◽  
Bristle Number ◽  
Optimum Selection ◽  
Different Types ◽  
Males And Females ◽  
Number Of Individuals

SUMMARYAn experimental evaluation of Jódar & López-Fanjul's (1977) theoretical treatment of the optimum proportions to select when the numbers of males and females scored are unequal has been carried out for sternopleural bristle number in Drosophila melanogaster. Three different values of the sex-ratio (c) were considered (c = 1, 4 and 10) for the same total number of individuals scored per generation. For each c value two types of line were selected with proportions theoretically maximizing the response to be attained after 10 or 20 generations, respectively. Thus, there were six types of lines and each type was replicated sixfold. A good qualitative agreement was found between the observed and the expected rankings of the different types of selected lines at the designated generations.

scholarly journals Selection for and against a canalized phenotype in Drosophila melanogaster

1967 ◽  
Vol 10 (1) ◽  
pp. 21-33 ◽  
Author(s):  
S. S. Y. Young
Keyword(s):  
Drosophila Melanogaster ◽  
Lower Proportion ◽  
Modifier Genes ◽  
Wild Type ◽  
Appreciable Change ◽  
Bristle Number ◽  
Alternative Hypotheses ◽  
Males And Females ◽  
Selection For ◽  
Relative Change

Selection for and against the canalized phenotype in scutellar bristles was attempted in two selection lines and a randomly selected line was used as control. The selection lines were the Decanalization line (D) and the Canalization line (N). The D line was maintained by matings of scute males (scwbl) with three scutellars with wild-type females (scwbl/yw) with five bristles, in the N line scute males with four bristles were mated with wild-type females also with four bristles, while in the C line males and females of the above genotypes were selected at random. The lines were established from a sample of flies taken from a line selected for high scutellar numbers.After eighteen generations of selection the C line was characterized by a regression of mean bristle number without appreciable change in variance. Relative to the N line, the D population showed a lower proportion of flies having four scutellars, a higher variance in bristle numbers, and a higher proportion of four-bristle scute flies having abnormal patterns.Two alternative hypotheses were advanced to account for the results of this experiment. The first postulated a relative change in the widths of the four-bristle canalization zones in the selection lines, while the second suggested a relative change in frequencies of specific modifier genes for scutellars in scute and in wild-type genotypes of the lines. The evidence favours the latter hypothesis.

scholarly journals Genetic differences between populations of Drosophila melanogaster for a quantitative trait: I. Laboratory populations

1973 ◽  
Vol 22 (1) ◽  
pp. 51-68 ◽  
Author(s):  
C. López-Fanjul ◽  
W. G. Hill
Keyword(s):  
Drosophila Melanogaster ◽  
Gene Frequency ◽  
Total Response ◽  
Selected Lines ◽  
Synthetic Populations ◽  
Bristle Number ◽  
Laboratory Populations ◽  
Selection For ◽  
Different Origins ◽  
Two Populations

SUMMARYAn experiment was carried out to test whether two laboratory cage populations of Drosophila melanogaster from different origins (Kaduna and Pacific) differed in the genes for sternopleural bristle number. The means, variances and heritabilities of the two populations and the synthetic formed from crosses between them were very similar.Selection for low bristle number was practised in small replicate lines, six of each pure population and nine of the synthetic. On average, Pacific responded to selection rather more rapidly than either Kaduna or the synthetic, but there was little difference in the limit achieved.Crosses between replicates within populations were made and selection continued, and these lines subsequently crossed between populations and reselected. Additional response was obtained by this procedure but the crosses between the replicates of the pure and synthetic populations attained similar selection limits.An analysis of effects of individual chromosomes from the selected lines on bristle number indicated that the contribution of each chromosome to total response was about the same in Pacific, Kaduna and the synthetic.It is concluded that differences in gene frequency, rather than the presence or absence of particular alleles, are mainly responsible for the differences observed between the populations.

SPERM PREFERENCE IN DROSOPHILA MELANOGASTER  †

Genetics ◽  
1972 ◽  
Vol 71 (3) ◽  
pp. 417-427
Author(s):  
D Childress ◽  
D L Hartl
Keyword(s):  
Drosophila Melanogaster ◽  
Reproductive Tract ◽  
Meiotic Drive ◽  
Prior Exposure ◽  
Different Types

Abstract A mating is described in which the females appear actively to discriminate against one of the genotypes of sperm. The males in the mating carry T(1;4)B  S  , and the sperm type selected against is the B  S+4-bearing segregant. Prior exposure of the reproductive tract of the females to B  S+4-bearing sperm seems to enhance the ability of the females to subsequently discriminate against B  S+4-bearing sperm. Thus it appears that at least some females of Drosophila melanogaster do possess a mechanism whereby different types of sperm can be distinguished—the sperm preference observed in this system appears to be independent of the meiotic drive in the T(1;4)B  S males.

scholarly journals Hybrid dysgenesis-induced quantitative variation on the X chromosome of Drosophila melanogaster.

Genetics ◽  
1990 ◽  
Vol 124 (3) ◽  
pp. 627-636
Author(s):  
C Q Lai ◽  
T F Mackay
Keyword(s):  
Drosophila Melanogaster ◽  
X Chromosome ◽  
Quantitative Traits ◽  
Natural Populations ◽  
Quantitative Variation ◽  
Hybrid Dysgenesis ◽  
X Chromosomes ◽  
Bristle Number ◽  
Seven Generations ◽  
Polygenic Variation

Abstract To determine the ability of the P-M hybrid dysgenesis system of Drosophila melanogaster to generate mutations affecting quantitative traits, X chromosome lines were constructed in which replicates of isogenic M and P strain X chromosomes were exposed to a dysgenic cross, a nondysgenic cross, or a control cross, and recovered in common autosomal backgrounds. Mutational heritabilities of abdominal and sternopleural bristle score were in general exceptionally high-of the same magnitude as heritabilities of these traits in natural populations. P strain chromosomes were eight times more mutable than M strain chromosomes, and dysgenic crosses three times more effective than nondysgenic crosses in inducing polygenic variation. However, mutational heritabilities of the bristle traits were appreciable for P strain chromosomes passed through one nondysgenic cross, and for M strain chromosomes backcrossed for seven generations to inbred P strain females, a result consistent with previous observations on mutations affecting quantitative traits arising from nondysgenic crosses. The new variation resulting from one generation of mutagenesis was caused by a few lines with large effects on bristle score, and all mutations reduced bristle number.

scholarly journals Theoretical treatment of tight-binding inhibition of an enzyme. Ribonuclease inhibitor as special case

1988 ◽  
Vol 253 (2) ◽  
pp. 517-522 ◽  
Author(s):  
J M Fominaya ◽  
J M García-Segura ◽  
M Ferreras ◽  
J G Gavilanes
Keyword(s):  
Tight Binding ◽  
Theoretical Treatment ◽  
Inhibitor Protein ◽  
Ribonuclease Inhibitor ◽  
Rat Testis ◽  
Binding Inhibition ◽  
Different Types ◽  
Functional Consequences ◽  
Inhibitor System ◽  
Special Case

A general treatment of very tight-binding inhibition is described. It was applied to purified endogenous RNAase inhibitor from rat testis. This treatment discriminates among the different types of inhibition and allows for calculation of the inhibition parameters. When very tight-binding inhibitions are studied at similar molar concentrations of both enzyme and inhibitor, a further approach is required. This is also described and applied to the RNAase inhibitor. A Ki value of 3.2 x 10(-12) M was found for this inhibitor protein. On the basis of this result, it was considered inappropriate to classify this type of inhibitor in terms of competitive or non-competitive, as has been done for such inhibitors so far. Functional consequences of this analysis are discussed for the RNAase-RNAase inhibitor system.

Facultative heterochromatization in parahaploid male mealybugs: involvement of a heterochromatin-associated protein

Development ◽  
2001 ◽  
Vol 128 (19) ◽  
pp. 3809-3817 ◽  
Author(s):  
Silvia Bongiorni ◽  
Milena Mazzuoli ◽  
Stefania Masci ◽  
Giorgio Prantera
Keyword(s):  
Monoclonal Antibody ◽  
Drosophila Melanogaster ◽  
Constitutive Heterochromatin ◽  
Planococcus Citri ◽  
Chromosomal Protein ◽  
Paternal Chromosome ◽  
Localization Pattern ◽  
Males And Females ◽  
Male Specific ◽  
Nonhistone Chromosomal Protein

The behavior of chromosomes during development of the mealybug Planococcus citri provides one of the most dramatic examples of facultative heterochromatization. In male embryos, the entire haploid paternal chromosome set becomes heterochromatic at mid-cleavage. Male mealybugs are thus functionally haploid, owing to heterochromatization (parahaploidy). To understand the mechanisms underlying facultative heterochromatization in male mealybugs, we have investigated the possible involvement of an HP-1-like protein in this process. HP-1 is a conserved, nonhistone chromosomal protein with a proposed role in heterochromatinization in other species. It was first identified in Drosophila melanogaster as a protein enriched in the constitutive heterochromatin of polytene chromosome. Using a monoclonal antibody raised against the Drosophila HP-1 in immunoblot and immunocytological experiments, we provide evidence for the presence of an HP-1-like in Planococcus citri males and females. In males, the HP-1-like protein is preferentially associated with the male-specific heterochromatin. In the developing male embryos, its appearance precedes the onset of heterochromatization. In females, the HP-1-like protein displays a scattered but reproducible localization pattern along chromosomes. The results indicate a role for an HP-1-like protein in the facultative heterochromatization process.

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