Induced Crossing-Over Variation in the X-Chromosome of Drosophila

1926 ◽  
Vol 60 (667) ◽  
pp. 192-195 ◽  
Author(s):  
H. J. Muller
Keyword(s):  
X Chromosome ◽  
Crossing Over

scholarly journals mus309 mutation, defective in DNA double-strand break repair, affects intergenic but not intragenic meiotic recombination in Drosophila melanogaster

2005 ◽  
Vol 86 (3) ◽  
pp. 185-191 ◽  
Author(s):  
PETTER PORTIN
Keyword(s):  
X Chromosome ◽  
Meiotic Recombination ◽  
Strand Break ◽  
Double Strand Break ◽  
Double Strand Break Repair ◽  
Crossing Over ◽  
Dna Double Strand Break ◽  
D Loop ◽  
Break Repair ◽  
Strand Annealing

The effect was investigated of the hypomorphic DNA double-strand break repair, notably synthesis-dependent strand annealing, deficient mutation mus309 on the third chromosome of Drosophila melanogaster on intergenic and intragenic meiotic recombination in the X chromosome. The results showed that the mutation significantly increases the frequency of intergenic crossing over in two of three gene intervals of the X chromosome studied. Interestingly the increase was most prevalent in the tip of the X chromosome where crossovers normally are least frequent per physical map unit length. In particular crossing over interference was also affected, indicating that the effect of the mus309 mutation involves preconditions of crossing over but not the event of crossing over itself. On the other hand, the results also show that most probably the mutation does not have any effect on intragenic recombination, i.e. gene conversion. These results are fully consistent with the present molecular models of meiotic crossing over initiated by double-strand breaks of DNA followed by formation of a single-end-invasion intermediate, or D-loop, which is subsequently processed to generate either crossover or non-crossover products involving formation of a double Holliday junction. In particular the results suggest that the mus309 gene is involved in resolution of the D-loop, thereby affecting the choice between double-strand-break repair (DSBR) and synthesis-dependent strand annealing (SDSA) pathways of meiotic recombination.

scholarly journals Does RNA interference influence meiotic crossing over in Drosophila melanogaster?

2008 ◽  
Vol 90 (3) ◽  
pp. 253-258 ◽  
Author(s):  
ERIC W. CROSS ◽  
MICHAEL J. SIMMONS
Keyword(s):  
Drosophila Melanogaster ◽  
Rna Interference ◽  
X Chromosome ◽  
Maternal Effect ◽  
Crossing Over ◽  
Crossover Frequency ◽  
Chromosome Iii ◽  
Chromosome Ii ◽  
Balancer Chromosomes ◽  
Balancer Chromosome

SummaryMutations in the RNA interference (RNAi) genes aubergine (aub), homeless and piwi were tested for effects on the frequency, distribution and coincidence of meiotic crossovers in the long arm of the X chromosome. Some increases in crossover frequency were seen in these tests, but they may have been due to a maternal effect of the balancer chromosomes that were used to maintain the RNAi mutations in stocks rather than to the RNAi mutations themselves. These same balancers produced strong zygotic interchromosomal effects when tested separately. Mutations in aub and piwi did not affect the frequency of crossing over in the centric heterochromatin of chromosome II; nor did a balancer chromosome III.

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 Controlling elements in the mouse X-chromosome

1970 ◽  
Vol 15 (2) ◽  
pp. 183-195 ◽  
Author(s):  
B. M. Cattanach ◽  
J. N. Perez ◽  
C. E. Pollard
Keyword(s):  
X Chromosome ◽  
Crossing Over ◽  
Experimental Conditions ◽  
Responsible Mechanism ◽  
Maize Type ◽  
Controlling Elements ◽  
Controlling Element

SUMMARYThe frequency and nature of the changes in ‘state’ of the mouse X-chromosome controlling element (inactivation centre) have been investigated on an inbred background. The results indicate with near-certainty that meiotic crossing over is the responsible mechanism and that the frequency of recombination between the T(1; X)Ct breakpoint and the locus of the controlling element is approximately 3%. Maize-type ‘changes in state’ may occur under other experimental conditions. The data do not distinguish on which side of the autosomal insertion the element lies but when combined with observations of other investigators suggest that the location must be on the Mo-Ta side and very close to Ta.

scholarly journals A cis-acting locus that promotes crossing over between X chromosomes in Caenorhabditis elegans.

Genetics ◽  
1994 ◽  
Vol 136 (3) ◽  
pp. 887-902 ◽  
Author(s):  
A M Villeneuve
Keyword(s):  
Caenorhabditis Elegans ◽  
X Chromosome ◽  
Sharp Decrease ◽  
Crossing Over ◽  
Meiotic Pairing ◽  
X Chromosomes ◽  
Cis Acting ◽  
Pairing Site ◽  
High Level ◽  
Pairing Center

Abstract This study reports the characterization of a cis-acting locus on the Caenorhabditis elegans X chromosome that is crucial for promoting normal levels of crossing over specifically between the X homologs and for ensuring their proper disjunction at meiosis I. The function of this locus is disrupted by the mutation me8, which maps to the extreme left end of the X chromosome within the region previously implicated by studies of X; A translocations and X duplications to contain a meiotic pairing site. Hermaphrodites homozygous for a deletion of the locus (Df/Df) or heterozygous for a deletion and the me8 mutation (me8/Df) exhibit extremely high level of X chromosome nondisjunction at the reductional division; this is correlated with a sharp decrease in crossing over between the X homologs as evidenced both by reductions in genetic map distances and by the presence of achiasmate chromosomes in cytological preparations of oocyte nuclei. Duplications of the wild-type region that are unlinked to the X chromosome cannot complement the recombination and disjunction defects in trans, indicating that this region must be present in cis to the X chromosome to ensure normal levels of crossing over and proper homolog disjunction. me8 homozygotes exhibit an altered distribution of crossovers along the X chromosome that suggests a defect in processivity along the X chromosome of an event that initiates at the chromosome end. Models are discussed in which the cis-acting locus deleted by the Dfs functions as a meiotic pairing center that recruits trans-acting factors onto the chromosomes to nucleate assembly of a crossover-competent complex between the X homologs. This pairing center might function in the process of homolog recognition, or in the initiation of homologous synapsis.

Structure, organization, and sequence of alpha satellite DNA from human chromosome 17: evidence for evolution by unequal crossing-over and an ancestral pentamer repeat shared with the human X chromosome

1986 ◽  
Vol 6 (9) ◽  
pp. 3156-3165
Author(s):  
J S Waye ◽  
H F Willard
Keyword(s):  
Human Chromosome ◽  
X Chromosome ◽  
Repeat Unit ◽  
Higher Order ◽  
Chromosome 17 ◽  
Crossing Over ◽  
Human Chromosomes ◽  
Alpha Satellite ◽  
Unequal Crossing Over ◽  
Human Chromosome 17

The centromeric regions of all human chromosomes are characterized by distinct subsets of a diverse tandemly repeated DNA family, alpha satellite. On human chromosome 17, the predominant form of alpha satellite is a 2.7-kilobase-pair higher-order repeat unit consisting of 16 alphoid monomers. We present the complete nucleotide sequence of the 16-monomer repeat, which is present in 500 to 1,000 copies per chromosome 17, as well as that of a less abundant 15-monomer repeat, also from chromosome 17. These repeat units were approximately 98% identical in sequence, differing by the exclusion of precisely 1 monomer from the 15-monomer repeat. Homologous unequal crossing-over is suggested as a probable mechanism by which the different repeat lengths on chromosome 17 were generated, and the putative site of such a recombination event is identified. The monomer organization of the chromosome 17 higher-order repeat unit is based, in part, on tandemly repeated pentamers. A similar pentameric suborganization has been previously demonstrated for alpha satellite of the human X chromosome. Despite the organizational similarities, substantial sequence divergence distinguishes these subsets. Hybridization experiments indicate that the chromosome 17 and X subsets are more similar to each other than to the subsets found on several other human chromosomes. We suggest that the chromosome 17 and X alpha satellite subsets may be related components of a larger alphoid subfamily which have evolved from a common ancestral repeat into the contemporary chromosome-specific subsets.

Behaviour of the Ring-Chromosome in Drosophila Melanogaster

1950 ◽  
Vol 64 (2) ◽  
pp. 199-215
Author(s):  
P. Battacharya
Keyword(s):  
X Chromosome ◽  
Chromosome Region ◽  
Ring Chromosome ◽  
Crossing Over ◽  
Early Cleavage ◽  
Ring Chromosomes ◽  
Single Cross ◽  
Or Genes ◽  
To Receive ◽  
Double Cross

SynopisThe genetical studies on ring-chromosomes in Drosophila show that there is no interlocking of chromatids at mitosis.Dicentric ring-chromosomes formed at meiosis on being pulled apart do not become broken with subsequent reunion of the broken ends. This may be due to the failure of these chromosomes either to rejoin or to become broken at all.The results make it probable that there is a gene or genes located in one of chromocentral regions of the X-chromosome of Drosophila, probably in the region at the distal end, which has a function in ensuring the orderly segregation of the chromatids in the early cleavage stages of the fertilised eggs. Hence the absence of this chromosome region results in a tendency to gynandromorphism.Results indicate the incorrectness of the view that the inviable zygotes and the patroclinous males found in the ring-chromosome stock arise from different kinds of eggs (single cross-over and progressive double cross-over respectively, as proposed by L. V. Morgan). Both arise from eggs that have for any reason failed to receive a monocentric X-chromosome. This result occurs in all cases of digressive double crossing-over and in half the cases of progressive double crossing-over. Such virtually X-less eggs, when fertilised by an X-bearing sperm, form patroclinous males, and when fertilised by a Y-bearing sperm, form inviable zygotes. The classes thus found are therefore equal in number.

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