scholarly journals THE EFFECT OF RECOMBINATION-DEFECTIVE MEIOTIC MUTANTS ON FOURTH-CHROMOSOME CROSSING OVER IN DROSOPHILA MELANOGASTER

Genetics ◽  
1978 ◽  
Vol 90 (4) ◽  
pp. 699-712
Author(s):  
L Sandler ◽  
Paul Szauter
Keyword(s):  
Drosophila Melanogaster ◽  
Spatial Distribution ◽  
The Other ◽  
Crossing Over ◽  
Chromosome 4 ◽  
Wild Type ◽  
Fourth Chromosome ◽  
Meiotic Mutants ◽  
Other Hand

ABSTRACT Crossing over was measured on the normally achiasmate fourth chromosome in females homozygous for one of our different recombination-defective meiotic mutants. Under the influence of those meiotic mutants that affect the major chromosomes by altering the spatial distribution of exchanges, meiotic fourth-chromosome recombinants were recovered irrespective of whether or not the meiotic mutant decreases crossing over on the other chromosomes. No crossing over, on the other hand, was detected on chromosome 4 in either wild type or in the presence of a meiotic mutant that decreases the frequency, but that does not affect the spatial distribution, of exchange on the major chromosomes. It is concluded from these observations that (a) in wild type there are regional constraints on exchange that can be attenuated or eliminated by the defects caused by recombination-defective meiotic mutants; (b) these very constraints account for the absence of recombination on chromosome 4 in wild type; and (c) despite being normally achiasmate, chromosome 4 responds to recombination-defective meiotic mutants in the same way as do the other chromosomes.

scholarly journals Mechanism of suppression in Drosophila melanogaster VIII. Comparison of su(s) alleles for ability to suppress the mutants purple, vermilion, and speck

1982 ◽  
Vol 40 (1) ◽  
pp. 19-32 ◽  
Author(s):  
K. Bruce Jacobson ◽  
E. H. Grell ◽  
John J. Yim ◽  
April L. Gardner
Keyword(s):  
Drosophila Melanogaster ◽  
Relative Effectiveness ◽  
The Other ◽  
Wild Type ◽  
Tryptophan Oxygenase ◽  
Other Hand ◽  
Type Activity ◽  
S Alleles ◽  
Suppressor Of Sable ◽  
Marked Suppression

SUMMARYThe suppressor of sable [su(s)2] restores the function of vermilion (v), purple (pr) and speck (sp) as well as sable (s) in Drosophila melanogaster. In this report various alleles of su(s) are compared for their relative effectiveness on three target mutations, v, pr and sp. Three criteria for suppression of pr and v were employed: visible phenotype, eye pigment levels (drosopterins and xanthommatin) and enzyme levels (sepiapterin synthase and tryptophan oxygenase). For sp only the visible phenotype was examined. By all three criteria pr was found to be more easily suppressed than v; v and sp were comparable. By use of pr with various alleles of su(s) either homozygously or in heterozygous combination with su(s)+, the extent of suppression of pr can be best demonstrated by observing the levels of sepiapterin synthase; normal levels of drosopterins were found in females when sepiapterin synthase was only 20% of normal. On the other hand, the extent of suppression of v is best demonstrated by the amount of xanthommatin eye pigment, because even the suppressed vermilion fly has < 10% of wild-type activity of tryptophan oxygenase when 1-day-old flies are examined; in older flies this enzyme can be as high as 50% of wild type. From these results we also demonstrated that su(s)2, and other alleles, are not recessive but, in heterozygous combination with su(s)+, cause marked suppression of pr and slight, but reproducible, suppression of v. The purple mutation, therefore, is particularly useful for studying the mechanism of suppression as well as for obtaining new mutant alleles of su(s).

Homologous recombination involving a large heterology in Escherichia coli.

Genetics ◽  
1988 ◽  
Vol 119 (4) ◽  
pp. 759-769
Author(s):  
K Yamamoto ◽  
N Takahashi ◽  
H Yoshikura ◽  
I Kobayashi
Keyword(s):  
Escherichia Coli ◽  
Gene Conversion ◽  
Kanamycin Resistance ◽  
Coli Strain ◽  
The Other ◽  
Reca Gene ◽  
Inverted Repeats ◽  
Crossing Over ◽  
Wild Type ◽  
Parental Allele

Abstract Recombination between two different deletion alleles of a gene (neo) for neomycin and kanamycin resistance was studied in an Escherichia coli sbcA- recB-C- strain. The two homologous regions were in an inverted orientation on the same plasmid molecule. Kanamycin-resistant plasmids were selected and analyzed. The rate of recombination to form kanamycin-resistant plasmids was decreased by mutations in the recE, recF and recJ genes, but was not decreased by a mutation in the recA gene. It was found that these plasmids often possessed one wild-type kanamycin-resistant allele (neo+) while the other neo allele was still in its original (deletion) form. Among kanamycin-resistant plasmids with one wild-type and one parental allele it was often found that the region between the inverted repeats had been flipped (turned around) with respect to sites outside the inverted repeats. These results were interpreted as follows. Gene conversion, analogous to gene conversion in eukaryotic meiosis, is responsible for a unidirectional transfer of information from one neo deletion allele to the other. The flipping of the region between the inverted repeats is interpreted as analogous to the crossing over associated with gene conversion in eukaryotic meiosis. In contrast with a rec+ strain, these products cannot be explained by two rounds of reciprocal crossing over involving a dimeric form as an intermediate. In the accompanying paper we present evidence that gene conversion by double-strand gap repair takes place in the same E. coli strain.

AUTOSOMAL MODIFIERS OF THE BOBBED PHENOTYPE ARE A MAJOR COMPONENT OF THE rDNA MAGNIFICATION PARADOX IN DROSOPHILA MELANOGASTER

Genetics ◽  
1986 ◽  
Vol 113 (2) ◽  
pp. 305-319
Author(s):  
Craig H Marcus ◽  
Anne E Zitron ◽  
David A Wright ◽  
R Scott Hawley
Keyword(s):  
Drosophila Melanogaster ◽  
Epistatic Effect ◽  
The Other ◽  
Wild Type ◽  
The Stability ◽  
Kinetics Of

ABSTRACT rDNA magnification in Drosophila melanogaster is defined experimentally as the ability of bb/Ybb  - males to produce exceptional progeny that are wild type with respect to rDNA associated phenotypes. Here, we show that some of these bobbed-plus progeny result not from genetic reversion at the bb locus but rather from variants at two or more autosomal loci that ameliorate the bobbed phenotype of rDNA deficient males in Drosophila. In doing so we resolve several aspects of a long-standing paradox concerning the phenomenon of rDNA magnification. This problem arose from the use of two genetic assays, which were presumed to be identical, but paradoxically, produced conflicting data on both the kinetics of reversion and the stability of magnified bb  + chromosomes. We resolve this problem by demonstrating that in one assay bobbed-plus progeny arise primarily by genetic reversion at the bobbed locus, whereas in the other assay bobbed-plus progeny arise both by reversion and by an epistatic effect of autosomal modifiers on the bobbed phenotype. We further show that such modifiers can facilitate the appearance of phenotypically bobbed-plus progeny even under conditions where genetic reversion is blocked by magnification defective mutants. Finally, we present a speculative model relating the action of these modifiers to the large increases in rDNA content observed in males undergoing magnification.

Nutritional Requirement for 4-Aminobenzoate Caused by Mutation of Dihydropteroate Synthetase

1976 ◽  
Vol 31 (5-6) ◽  
pp. 285-287 ◽  
Author(s):  
Helmut Rappold ◽  
Adelbert Bacher
Keyword(s):  
Parent Strain ◽  
The Other ◽  
Synthetase Activity ◽  
Nutritional Requirement ◽  
Wild Type ◽  
Aerobacter Aerogenes ◽  
Low Level ◽  
Other Hand ◽  
High Concentrations

Abstract Aerobacter aerogenes mutant 62-1 AC requires high concentrations of 4-aminobenzoate for growth. The mutant accumulates N-glucosyl-4-aminobenzoate and has an intact 4-aminobenzoate synthetase (Bacher, Gilch, Rappold, and Lingens, Z. Naturforsch. 28c, 614 - 617 [1973]). On the other hand the ability of the mutant to synthesize dihydropteroate is markedly reduced. The dihydropteroate synthetase level of mutant 62-1 AC is 1% as compared to the parent strain. Spontaneous revertants of mutant 62-1 AC show wild type levels of dihydropteroate synthetase. We conclude that the requirement for 4-aminobenzoate in mutant 62-1 AC is due to poor utilization of 4-aminobenzoate as a consequence of the low level of dihydropteroate synthetase activity.

H-Ras Is Involved in the Inside-out Signaling Pathway of Interleukin-3–Induced Integrin Activation

Blood ◽  
1999 ◽  
Vol 93 (5) ◽  
pp. 1540-1548 ◽  
Author(s):  
Hirohiko Shibayama ◽  
Naoyuki Anzai ◽  
Stephen E. Braun ◽  
Seiji Fukuda ◽  
Charlie Mantel ◽  
...  
Keyword(s):  
Signaling Pathway ◽  
Dominant Negative ◽  
The Other ◽  
Wild Type ◽  
Integrin Activation ◽  
Mapk Kinase ◽  
Interleukin 3 ◽  
Other Hand ◽  
Inside Out ◽  
Constitutively Active

Abstract The proto-oncogene product, p21ras, has been implicated in the cellular mechanism of adhesion, although its precise role has been controversial. Numerous cytokines and growth-factors activate Ras, which is an important component of their growth-promoting signaling pathways. On the other hand, the role of Ras in cytokine-induced adhesion has not been elucidated. We therefore investigated the function of H-Ras in the inside-out signaling pathway of interleukin-3 (IL-3)–induced integrin activation in the murine Baf3 cell line after transfection of cells with either constitutively active, dominant-negative, or wild-type H-Ras cDNAs. Adhesion of Baf3 cells to fibronectin was induced by IL-3 in a dose-dependent manner via very late antigen-4 (VLA-4; 4β1 integrins) and VLA-5 (5β1 integrins) activation. On the other hand, IL-4 did not induce the adhesion of Baf3 cells to fibronectin, although IL-4 did stimulate the cell proliferation of Baf3 cells. Constitutively active H-Ras–transfected Baf3 cells adhered to fibronectin without IL-3 stimulation through VLA-4 and VLA-5, whereas dominant-negative H-Ras–transfected Baf3 cells showed significantly less adhesion induced by IL-3 compared with wild-type and constitutively active H-Ras–transfected Baf3 cells. Anti-β1 integrin antibody (clone; 9EG7), which is known to change integrin conformation and activate integrins, induced the adhesion of dominant-negative H-Ras–transfected Baf3 cells as much as the other types of H-Ras–transfected Baf3 cells. 8-Br-cAMP, Dibutyryl-cAMP, Ras-Raf-1 pathway inhibitors, and PD98059, a MAPK kinase inhibitor, suppressed proliferation and phosphorylation of MAPK detected by Western blotting with anti–phospho-MAPK antibody, but not adhesion of any type of H-Ras–transfected Baf3 cells, whereas U-73122, a phospholipase C (PLC) inhibitor, suppressed adhesion of these cells completely. These data indicate that H-Ras and PLC, but not Raf-1, MAPK kinase, or the MAPK pathway, are involved in the inside-out signaling pathway of IL-3–induced VLA-4 and VLA-5 activation in Baf3 cells.

“To engraft ourselves on foreign stocks”: Byron’s Poetics of Acculturation

2006 ◽  
Author(s):  
Maria Schoina
Keyword(s):  
Social Relations ◽  
Mary Shelley ◽  
The Other ◽  
Local Culture ◽  
Crossing Over ◽  
Rhetorical Strategies ◽  
Time And Space ◽  
Other Hand ◽  
The One ◽  
Culture Acquisition

Abstract Considering the largely unacknowledged connection between Byron and Mary Shelley on the logistics which pertain to the experience of crossing-over cultures, this paper investigates the notion of authentic Italianisation as exemplified in their related texts, and discusses its problematics in the context of the dominant themes and preoccupations in Romantic culture. Thus, on the one hand, my paper examines how the Romantic anticipation of being immersed in local culture and of “going native” is articulated – or rather, performed – by Byron himself, by considering specific rhetorical strategies and figures of filiation he used to ground his relationship to Italian place. More specifically, I contend that although Byron’s polymorphic identification to Italian place is constructed in the imagination, it is also grounded in time- and space-bound actions and involves a structure of social relations. On the other hand, the paper delineates how Byron’s idiosyncratic immersion into Italianness is theorised by Mary Shelley and counted on as a model of second culture acquisition.

CROSSING OVER IN A DOUBLE TRANSLOCATION IN DROSOPHILA

1972 ◽  
Vol 14 (1) ◽  
pp. 129-137 ◽  
Author(s):  
A. S. Robinson ◽  
C. F. Curtis
Keyword(s):  
Drosophila Melanogaster ◽  
Pest Control ◽  
The Other ◽  
Crossing Over ◽  
Male And Female ◽  
Differential Segment ◽  
Translocation Heterozygote

The production and fertility of a double translocation heterozygote in Drosophila melanogaster are reported. A difference in the fertility of male and female double heterozygotes was recorded and explained on the basis of crossing over, occurring in the differential segments of female double heterozygotes, producing extra unbalanced gametes. It was shown that crossing over was absent from one differential segment but the amount of crossing over occurring in the other differential segment was measured. The possible use of multiple translocation systems for pest control is discussed with particular reference to the use of double translocation heterozygotes.

scholarly journals DEVELOPMENT IN GENETIC MOSAICS OF ARISTAPEDIA, A HOMOEOTIC MUTANT OF DROSOPHILA MELANOGASTER

Genetics ◽  
1974 ◽  
Vol 76 (4) ◽  
pp. 767-774
Author(s):  
J H Postlethwait ◽  
J R Girton
Keyword(s):  
Drosophila Melanogaster ◽  
Cell Line ◽  
Crossing Over ◽  
Wild Type ◽  
Genetic Mosaics ◽  
X Ray ◽  
A Cell

ABSTRACT Development of the homoeotic mutation, aristapedia (ss  a), was investigated by means of genetic mosaics. The wild-type alleles of aristapedia and the bristle markers yellow, singed, and forked were removed from cells at different times in development by X-ray induced somatic crossing-over. The phenotype of the resulting clones was examined in order to ascertain whether it was leg or antenna. The y sn f; ssa clones showed a leg phenotype if induced before the mid-third instar, but showed an antennal phenotype if induced after this time. Late non-expression of ss  a may be due either to an influence of surrounding ss  + tissues on the small ss  a clones, or to a persistence of the effect of ss  + for one or two cell generations after it is removed from a cell line.

scholarly journals Genetic and physical analysis of double-strand break repair and recombination in Saccharomyces cerevisiae.

Genetics ◽  
1989 ◽  
Vol 122 (3) ◽  
pp. 519-534 ◽  
Author(s):  
N Rudin ◽  
E Sugarman ◽  
J E Haber
Keyword(s):  
Strand Break ◽  
Double Strand Break ◽  
The Other ◽  
Crossing Over ◽  
Physical Analysis ◽  
Wild Type ◽  
Inverted Orientation ◽  
Mating Type Switching ◽  
A Site ◽  
Kinetics Of

Abstract We have investigated HO endonuclease-induced double-strand break (DSB) recombination and repair in a LACZ duplication plasmid in yeast. A 117-bp MATa fragment, embedded in one copy of LACZ, served as a site for initiation of a DSB when HO endonuclease was expressed. The DSB could be repaired using wild-type sequences located on a second, promoterless, copy of LACZ on the same plasmid. In contrast to normal mating-type switching, crossing-over associated with gene conversion occurred at least 50% of the time. The proportion of conversion events accompanied by exchange was greater when the two copies of LACZ were in direct orientation (80%), than when inverted (50%). In addition, the fraction of plasmids lost was significantly greater in the inverted orientation. The kinetics of appearance of intermediates and final products were also monitored. The repair of the DSB is slow, requiring at least an hour from the detection of the HO-cut fragments to completion of repair. Surprisingly, the appearance of the two reciprocal products of crossing over did not occur with the same kinetics. For example, when the two LACZ sequences were in the direct orientation, the HO-induced formation of a large circular deletion product was not accompanied by the appearance of a small circular reciprocal product. We suggest that these differences may reflect two kinetically separable processes, one involving only one cut end and the other resulting from the concerted participation of both ends of the DSB.

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