scholarly journals CORRELATIONS BETWEEN CHROMOSOME SEGMENTS AND FITNESS IN DROSOPHILA MELANOGASTER. II. THE X CHROMOSOME AND EGG VIABILITY

Genetics ◽  
1979 ◽  
Vol 92 (2) ◽  
pp. 595-601
Author(s):  
William Chapco
Keyword(s):  
Drosophila Melanogaster ◽  
X Chromosome ◽  
Egg Production ◽  
Egg Viability ◽  
X Chromosomes ◽  
Isogenic Lines ◽  
Chromosome Segments

ABSTRACT Unmarked segments within the X chromosomes of four different Drosophila melanogaster isogenic lines were assessed with respect to egg-to-adult viability. The results were compared with those of an earlier study involving egg production. All segments influence both traits, but to extents that are dependent upon the strains being compared. Segmental effects are also a function of the genetical background, which, in this case, constitutes material within the same chromowme. With respect to both traits, the segments are not necessarily parallel in their effects. A segment that increases fecundity, for example, may or may not augment viability. The possibility of manipulating chromosomal segments to improve "yield" in organisms is explored.

scholarly journals CORRELATIONS BETWEEN CHROMOSOME SEGMENTS AND FITNESS IN DROSOPHILA MELANOGASTER. I. THE X CHROMOSOME AND EGG PRODUCTION

Genetics ◽  
1977 ◽  
Vol 85 (4) ◽  
pp. 721-732
Author(s):  
William Chapco
Keyword(s):  
Drosophila Melanogaster ◽  
X Chromosome ◽  
Egg Production ◽  
Position Effect ◽  
X Chromosomes ◽  
Heterozygous Condition ◽  
Coupling Phase ◽  
Isogenic Lines ◽  
Apparent Relationship ◽  
Chromosome Segments

ABSTRACT Unmarked segments within the X chromosomes of four different Drosophila melanogaster isogenic lines were assessed with respect to egg production. By making a series of crosses among original and derived recombinant lines, it was possible to estimate parameters representing additive, dominance and interaction effects of the segments. It was shown that whereas most of the segments were additive for egg production when homozygous, they all displayed dominance in the heterozygous condition. Two of the strains were characterized by intersegmental interaction. A possible position effect was detected for these same two strains, with flies in the coupling phase laying more eggs than those in the repulsion configuration. There was no apparent relationship between the number of eggs laid and the amount of heterozygosity within the X chromosome.

CORRELATIONS BETWEEN CHROMOSOME SEGMENTS AND FITNESS IN DROSOPHILA MELANOGASTER. IV. FECUNDITY, VIABILITY AND THE THIRD CHROMOSOME

1980 ◽  
Vol 22 (3) ◽  
pp. 405-410 ◽  
Author(s):  
William Chapco
Keyword(s):  
Drosophila Melanogaster ◽  
X Chromosome ◽  
Genetic Background ◽  
Egg Production ◽  
Adjacent Segment ◽  
Egg Viability ◽  
Clear Pattern ◽  
The Third ◽  
Chromosome Segments ◽  
Agricultural Implications

Unmarked segments within the third chromosomes of three different Drosophila melanogaster lines were assessed for their effects on egg production and egg viability. By making a series of crosses among original and derived recombinant lines, it was possible to estimate parameters representing additive, dominance (for egg production), and interaction effects of the segments. Each segment influences both traits, but to extents which are dependent on the genetic background provided by an adjacent segment. There is no clear pattern, however, with respect to the segments' joint effects on the two characters. Unlike in the previous study involving the X chromosome, the majority of the derived recombinant lines were superior in fitness to their original lines. The agricultural implications of this result with respect to the manipulation of chromosomal segments in order to achieve higher yields are discussed.

scholarly journals HETEROCHROMATIC EFFECTS ON THE BEHAVIOR OF REVERSED ACROCENTRIC COMPOUND-X CHROMOSOMES IN DROSOPHILA MELANOGASTER

Genetics ◽  
1979 ◽  
Vol 91 (3) ◽  
pp. 537-551
Author(s):  
L Sandler ◽  
Joseph O'Tousa
Keyword(s):  
Drosophila Melanogaster ◽  
Y Chromosome ◽  
X Chromosome ◽  
Egg Production ◽  
Heterochromatic Region ◽  
Meiotic Behavior ◽  
X Chromosomes ◽  
General Properties ◽  
Single Exchange

ABSTRACT Previous studies of reversed acrocentric compound-X chromosomes suggested peculiar influences of heterochromatin on both the synthesis and meiotic behavior of such compounds. It seemed, with respect to synthesis, that the long arm of the Y chromosome on an X.YL chromosome was necessary in order for the heterochromatic exchange giving rise to reversed acrocentrics to occur, even though YL itself did not participate in the compound-generating event. With respect to behavior, the resulting compounds appeared, presumably as a consequence of their singular generation, to contain an interstitial heterochromatic region that caused the distribution of exchanges between the elements of the compound to be abnormal (many zero and two-exchange tetrads with few, if any, single-exchange tetrads). Removing the interstitial heterochromatin (or, curiously, appending YL as a second arm of the compound) eliminated the recombinational anomalies and resulted in typical tetrad distributions.—We provide evidence that these peculiarities, while presumably real, were likely the consequence of a special X.YL chromosome that was used to synthesize the reversed acrocentrics examined in the early studies and are not general properties of either reversed acrocentric compounds or of interstitial heterochromatin. However, we show that specific heterochromatic regions do, in fact, profoundly influence the behavior of (apparently all) reversed acrocentric compound-X chromosomes. In particular, we demonstrate that specific portions of the Y chromosome and of the basal X-chromosome heterochromatin, when present as homologs for reversed acrocentric compounds, markedly and coordinately increase bath the frequency of exchange between the elements of the compound and the fertility (egg production) of compound-bearing females. It is, we suppose, some aspect of this heterochromatic effect, produced by the% special X.YL chromosome, that caused the earlier-analyzed compounds to exhibit the observed anomalies.

scholarly journals SITE-SPECIFIC INSTABILITY IN DROSOPHILA MELANOGASTER: EVIDENCE FOR TRANSPOSITION OF DESTABILIZING ELEMENT

Genetics ◽  
1982 ◽  
Vol 101 (3-4) ◽  
pp. 461-476
Author(s):  
Todd R Laverty ◽  
J K Lim
Keyword(s):  
Drosophila Melanogaster ◽  
X Chromosome ◽  
Lethal Mutation ◽  
Chromosome Rearrangements ◽  
Chromosome Break ◽  
Secondary Mutation ◽  
X Chromosomes ◽  
Site Specific ◽  
Normal Sequence ◽  
Lethal Mutations

ABSTRACT In this study, we show that at least one lethal mutation at the 3F-4A region of the X chromosome can generate an array of chromosome rearrangements, all with one chromosome break in the 3F-4A region. The mutation at 3F-4A (secondary mutation) was detected in an X chromosome carrying a reverse mutation of an unstable lethal mutation, which was mapped in the 6F1-2 doublet (primary mutation). The primary lethal mutation at 6F1-2 had occurred in an unstable chromosome (Uc) described previously (Lim 1979). Prior to reversion, the 6F1-2 mutation had generated an array of chromosome rearrangements, all having one break in the 6F1-2 doublet (Lim 1979, 1980). In the X chromosomes carrying the 3F-4A secondary lethal mutation the 6F1-2 doublet was normal and stable, as was the 3F-4A region in the X chromosome carrying the primary lethal mutation. The disappearance of the instability having a set of genetic properties at one region (6F1-2) accompanied by its appearance elsewhere in the chromosome (3F-4A) implies that a transposition of the destabilizing element took place. The mutant at 3F-4A and other secondary mutants exhibited all but one (reinversion of an inversion to the normal sequence) of the eight properties of the primary lethal mutations. These observations support the view that a transposable destabilizing element is responsible for the hypermutability observed in the unstable chromosome and its derivaties.

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.

Spontaneous formation of compound X chromosomes in Drosophila melanogaster.

Genetics ◽  
1988 ◽  
Vol 119 (1) ◽  
pp. 95-103
Author(s):  
R J Morrison ◽  
J D Raymond ◽  
J R Zunt ◽  
J K Lim ◽  
M J Simmons
Keyword(s):  
Drosophila Melanogaster ◽  
X Chromosome ◽  
The Other ◽  
X Chromosomes ◽  
Multiple Factors ◽  
Spontaneous Formation ◽  
Chromosome Attachment ◽  
Recombination Experiments ◽  
Attachment Process

Abstract Males carrying different X chromosomes were tested for the ability to produce daughters with attached-X chromosomes. This ability is characteristic of males carrying an X chromosome derived from 59b-z, a multiply marked X chromosome, and is especially pronounced in males carrying the unstable 59b-z chromosomes Uc and Uc-lr. Recombination experiments with one of the Uc-lr chromosomes showed that the formation of compound chromosomes depends on two widely separated segments. One of these is proximal to the forked locus and is probably proximal to the carnation locus. This segment may contain the actual site of chromosome attachment. The other essential segment lies between the crossveinless and vermilion loci and may contain multiple factors that influence the attachment process.

scholarly journals MEIOTIC BEHAVIOR OF COMPOUND AUTOSOMES IN FEMALES OF DROSOPHILA MELANOGASTER: INTERCHROMOSOMAL EFFECTS AND THE SOURCE OF SPONTANEOUS NONSEGREGATION

Genetics ◽  
1980 ◽  
Vol 96 (2) ◽  
pp. 455-470
Author(s):  
Hideh Harger ◽  
David G Holm
Keyword(s):  
Drosophila Melanogaster ◽  
X Chromosome ◽  
Inverse Correlation ◽  
Proximal Region ◽  
Crossing Over ◽  
X Chromosomes ◽  
Repulsion Phase ◽  
Base Level ◽  
Exchange Processes ◽  
Spontaneous Frequency

ABSTRACT In females of Drosophila melanogaster, compound autosomes enter the repulsion phase of meiosis uncommitted to a particular segregation pattern because their centromeres are not restricted to a bivalent pairing complex as a consequence of crossing over. Their distribution at anaphase, therefore, is determined by some meiotic property other than exchange pairing, a property that for many years has been associated with the concept of nonhomologous pairing. In the absence of heterologous rearrangements or a free Y chromosome, C(3L) and C(3R) are usually recovered in separate gametes, that is as products of meiotic segregation. Nevertheless, there is a regular, albeit infrequent, recovery of reciprocal meiotic products (the nonsegregational products) that are disomic and nullosomic for compound thirds. The frequency of these exceptions, which is normally between 0.5 and 5.0%, differs for the various strains examined, but remains constant for any given strain. Since previous studies have not uncovered a cause for this base level of nonsegregation, it has been referred to as the spontaneous frequency. In this study, crosses between males and females whose X chromosomes, as well as compound autosomes, are differentially marked reveal a highly significant positive correlation between the frequency of compound-autosome nonsegregation and the frequency of X-chromosome nondisjunction. However, an inverse correlation is found when the frequency of nondisjunction is related to the frequency of crossing over in the proximal region of the X chromosome. These findings have been examined with reference to the distributive pairing and the chromocentral models and interpreted as demonstrating (1) that nonsegregational meiotic events arise primarily as a result of nonhomologous interactions, (2) that forces responsible for the segregation of nonhomologous chromosomes are properties of the chromocentral region, and (3) that these forces come into expression after the exchange processes are complete.

scholarly journals MALE-STERILIZING INTERACTIONS BETWEEN DUPLICATIONS AND DEFICIENCIES FOR PROXIMAL X-CHROMOSOME MATERIAL IN DROSOPHILA MELANOGASTER

Genetics ◽  
1981 ◽  
Vol 99 (1) ◽  
pp. 49-64
Author(s):  
Rezaur Rahman ◽  
Dan L Lindsley
Keyword(s):  
Drosophila Melanogaster ◽  
X Chromosome ◽  
Male Fertility ◽  
Primary Spermatocyte ◽  
Single Factor ◽  
X Chromosomes ◽  
Recessive Lethal ◽  
Lethal Mutations ◽  
Y Chromosomes ◽  
Chromosome Material

ABSTRACT The genetic limits of sixty-four deficiencies in the vicinity of the euchromatic-heterochromatic junction of the X chromosome were mapped with respect to a number of proximal recessive lethal mutations. They were also tested for male fertility in combination with three Y chromosomes carrying different amounts of proximal X-chromosome-derived material (BSYy+, y+Ymal126 and y  +  Ymal  +). All deficiencies that did not include the locus of bb and a few that did were male-fertile in all male-viable Df(1)/Dp(1;Y) combinations. Nineteen bb deficiencies fell into six different classes by virtue of their male-fertility phenotypes when combined with the duplicated Y chromosomes. The six categories of deficiencies are consistent with a formalism that invokes three factors or regions at the base of the X, one distal and two proximal to bb, which bind a substance critical for precocious inactivation of the X chromosome in the primary spermatocyte. Free duplications carrying these regions or factors compete for the substance in such a way that, in the presence of such duplications, proximally deficient X chromosomes are unable to command sufficient substance for proper control of X-chromosome gene activity preparatory to spermatogenesis. We conclude that there is no single factor at the base of the X that is required for the fertility of males whose genotype is otherwise normal.

scholarly journals FITNESS EFFECTS OF EMS-INDUCED MUTATIONS ON THE X CHROMOSOME OF DROSOPHILA MELANOGASTER. II. HEMIZYGOUS FITNESS EFFECTS

Genetics ◽  
1977 ◽  
Vol 87 (4) ◽  
pp. 775-783
Author(s):  
Joyce A Mitchell ◽  
Michael J Simmons
Keyword(s):  
Drosophila Melanogaster ◽  
X Chromosome ◽  
Induced Mutations ◽  
Fitness Effect ◽  
X Chromosomes ◽  
Fitness Effects ◽  
Induced Mutants ◽  
Time Changes

ABSTRACT X chromosomes mutagenized with EMS were tested for their effects on the fitness of hemizygous carriers. The tests were carried out in populations in which treated and untreated X chromosomes segregated from matings between males and attached-X females; the populations were maintained for several generations, during which time changes in the frequencies of the treated and untreated chromosomes were observed. From the rates at which the frequencies changed, the fitness effects of the treated chromosomes were determined. It was found that flies hemizygous for a mutagenized chromosome were 1.7% less fit per mm EMS treatment than those hemizygous for an untreated chromosome. Since the same flies were only 0.5% per m m less viable than their untreated counterparts, the total fitness effect of an X chromosome carrying EMS-induced mutants is three to four times greater than its viability effect. By comparing the heterozygous effect of a mutagenized X chromosome on fitness with the corresponding hemizygous effect, the dominance value for the chromosome is estimated to be about 0.25.

scholarly journals Chromosomal basis of dosage compensation in drosophila: IX. cellular autonomy of the faster replication of the x chromosome in haplo-x cells of drosophila melanogaster and synchronous initiation

1977 ◽  
Vol 74 (1) ◽  
pp. 168-180 ◽  
Author(s):  
RN Chatterjee ◽  
AS Mukherjee
Keyword(s):  
Drosophila Melanogaster ◽  
Salivary Glands ◽  
X Chromosome ◽  
Initial Phase ◽  
X Chromosomes ◽  
Initiation Of Replication ◽  
A Genome ◽  
The Mean ◽  
Early Replication ◽  
X Cells

[(3)H]Thymidine labeling patterns have been examined in gynandric mosaic salivary glands of drosophila melanogaster. The Ring-X stock, R(1) w(ve)/In(1)dl 49, l (1) J1 y w lz(s), was used for this purpose. 365 labeled XX2A and 40 labeled XO2A nuclei were obtained from a total of 624 nuclei in nine pairs of mosaic salivary glands. It was observed that in all but those nuclei which had DD, 1C, and 2C patterns, the X chromosome of the XO2A nuclei always had fewer sites labeled than the X chromosomes of the XX2A nuclei, for a given pattern of the autosomes in either sex. Such asynchronous labeling of the X chromosome in the XO2A (male) nuclei was observed regardless of the proportion of the XO2A cells (2.0-73.7 percent), in the mosaic glands. Moreover, while the frequency of [(3)H]thymidine labeling for all of the 39 replicating units except the two late replicating sites (3C and 11A) in the X chromosome of the XO2A nuclei, was consistently lower than in the X chromosome of the XX2A nuclei, the mean number of grains on the X chromosome was relatively (to autosomes) similar in both XX2A and XO2A cells. The results, therefore, suggest that, as in XY2A larval glands, the X chromosome in the XO2A cells also completes the replication earlier than autosomes and that the XO2A nuclei show cellular autonomy with respect to the early replication of the X chromosome, like its counterpart, RNA transcription. Absence of the asynchrony during the initial phase (DD-2C) further completes the replication earlier but that the rate of replication of its DNA is possibly faster, and (b) that there might be a common regulation with respect to the initiation of replication of different chromosomes in a genome.

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