The basis of decreased recombination in certain outcrosses of Neurospora crassa

Genome ◽  
1992 ◽  
Vol 35 (3) ◽  
pp. 503-509 ◽  
Author(s):  
David D. Perkins ◽  
Maja Bojko
Keyword(s):  
Linkage Group ◽  
Genetic Background ◽  
Wild Strain ◽  
Laboratory Strain ◽  
Crossing Over ◽  
Group I ◽  
Marked Chromosome ◽  
Inbred Laboratory Strain ◽  
High Level ◽  
Chromosome Segments

Crossing over in a multiply marked segment of linkage group I was conspicuously reduced in outcrosses between a marked laboratory strain and each of six unrelated wild-collected strains, compared with crosses between inbred laboratory strains. The marked chromosome segment was transferred intact from the inbred strain to one of the wild-collected strains by seven recurrent backcrosses, and conversely, the corresponding segment of the wild strain was transferred to the inbred background by backcrossing to the multiply marked laboratory strain. Recombination was then monitored in crosses from parents having the marked and unmarked chromosome segments from the same or from unrelated sources. Meiotic crossing-over in the marked segment remained low in crosses between parents that were dissimilar with respect to genetic background, but crossing over was restored to a high level when the genetic background of both parents was that of the inbred laboratory strain, regardless of the source of the marked segments. Reduced recombination in outcrosses was therefore not due to heterologies in the marked segment but must be attributed to modifiers that are unlinked or distant from the monitored region.Key words: recombination, recombination control, crossing over, Neurospora.

SEX AND CROSSING OVER IN LINKAGE GROUP III OF TRIBOLIUM CASTANEUM

1977 ◽  
Vol 19 (2) ◽  
pp. 259-263 ◽  
Author(s):  
Alexander Sokoloff
Keyword(s):  
Sex Differences ◽  
Linkage Group ◽  
Tribolium Castaneum ◽  
Relative Position ◽  
Genetic Background ◽  
Crossing Over ◽  
Group Iii ◽  
The Third ◽  
Main Factors ◽  
Coleoptera Tenebrionidae

The relative position of the genes black (b), light ocular diaphragm (lod) and aureate (au) for the third linkage group of T. castaneum (Herbst) (Coleoptera, Tenebrionidae) has been determined as b – lod – au. The distances between the various genes vary, depending on the cross. The b++/+ lod au ♂ × + lod au/+ lod au ♀ crosses give the following recombination values: au – lod = 18.32 ± 1.21%; b – lod = 21.05 ± 1.51% and b – au = 37.43 ± 1.27%. The reciprocal crosses give au – lod = 27.67 ± 1.62%; b – lod = 13.97 ± 1.26% and b – au = 39.79 ± 1.78%. For the larger distances encompassed in the b – au region the recombination values in the two sexes were not significantly different. For the shorter b – lod region the recombination values were significantly larger in the females than in the males, while for the adjacent lod – au region the opposite was true. On the basis of the current literature it would appear that the main factors contributing to these sex differences in recombination are the modifiers which are different in the genetic background of the two sexes.

scholarly journals Location of factors enhancing crossing over on linkage group I of Neurospora

1973 ◽  
Vol 21 (2) ◽  
pp. 195-204
Author(s):  
Jenny Hargrave ◽  
S. F. H. Threlkeld
Keyword(s):  
Linkage Group ◽  
Distal Region ◽  
Proximal Region ◽  
Crossing Over ◽  
Group I ◽  
The Right

SUMMARYAn enhancement of cross-over frequencies previously reported by Newcombe & Threlkeld (1972) is shown to be due to two regions located on linkage group I, a few cross-over units to the right of the centromere. The distal region appears to be shorter than the proximal region, but equally effective in enhancing cross-over frequencies. The longer proximal region is readily divisable by cross-overs and probably spans several crossover units.

scholarly journals REVERSAL OF A NEUROSPORA TRANSLOCATION BY CROSSING OVER INVOLVING DISPLACED rDNA, AND METHYLATION OF THE rDNA SEGMENTS THAT RESULT FROM RECOMBINATION

Genetics ◽  
1986 ◽  
Vol 114 (3) ◽  
pp. 791-817
Author(s):  
David D Perkins ◽  
Robert L Metzenberg ◽  
Namboori B Raju ◽  
Eric U Selker ◽  
Edward G Barry
Keyword(s):  
Linkage Group ◽  
Distal Portion ◽  
Nucleolus Organizer ◽  
Rrna Genes ◽  
Molecular Evidence ◽  
Crossing Over ◽  
Wild Type ◽  
Type Locus ◽  
Group I ◽  
Chromosome Sequence

ABSTRACT In translocation OY321 of Neurospora crassa, the nucleolus organizer is divided into two segments, a proximal portion located interstitially in one interchange chromosome, and a distal portion now located terminally on another chromosome, linkage group I. In crosses of Translocation x Translocation, exceptional progeny are recovered nonselectively in which the chromosome sequence has apparently reverted to Normal. Genetic, cytological, and molecular evidence indicates that reversion is the result of meiotic crossing over between homologous displaced rDNA repeats. Marker linkages are wild type in these exceptional progeny. They differ from wild type, however, in retaining an interstitial block of rRNA genes which can be demonstrated cytologically by the presence of a second, small interstitial nucleolus and genetically by linkage of an rDNA restriction site polymorphism to the mating-type locus in linkage group I. The interstitial rDNA is more highly methylated than the terminal rDNA. The mechanism by which methylation enzymes distinguish between interstitial rDNA and terminal rDNA is unknown. Some hypotheses are considered.

scholarly journals Interspecific crosses and crossing-over in Neurospora

1972 ◽  
Vol 19 (2) ◽  
pp. 115-119 ◽  
Author(s):  
K. D. Newcombe ◽  
S. F. H. Threlkeld
Keyword(s):  
Linkage Group ◽  
Neurospora Crassa ◽  
Interspecific Crosses ◽  
Crossing Over ◽  
Centromere Region ◽  
Group I

SUMMARYThrough a series of backcrosses the centromere region of linkage group I of Neurospora crassa was transferred to the N. sitophila genome, and through another series of backcrosses the centromere region of linkage group I of N. sitophila was transferred to N. crassa. Strains thus synthesized showed, in further crosses, that the N. sitophila centromere region acts as a dominant enhancer of cross-over frequencies across linkage group I of the two species.

scholarly journals CROSSING-OVER AND INTERFERENCE IN THE CENTROMERE REGION OF LINKAGE GROUP I OF NEUROSPORA

Genetics ◽  
1962 ◽  
Vol 47 (9) ◽  
pp. 1243-1252
Author(s):  
B N Bole-Gowda ◽  
D D Perkins ◽  
W N Strickland
Keyword(s):  
Linkage Group ◽  
Crossing Over ◽  
Centromere Region ◽  
Group I

scholarly journals Resistance to Asian soybean rust in soybean lines with the pyramided three Rpp genes

2013 ◽  
Vol 13 (1) ◽  
pp. 75-82 ◽  
Author(s):  
Naoki Yamanaka ◽  
Noelle G Lemos ◽  
Miori Uno ◽  
Hajime Akamatsu ◽  
Yuichi Yamaoka ◽  
...  
Keyword(s):  
Genetic Background ◽  
Susceptible Variety ◽  
Soybean Rust ◽  
Phakopsora Pachyrhizi ◽  
Soybean Line ◽  
Pathogen Population ◽  
Resistance Level ◽  
Asian Soybean Rust ◽  
High Level

In this study, the influence of genetic background on the resistance level of a soybean line carrying Rpp2, Rpp4, and Rpp5 was evaluated by backcrossing it with a susceptible variety. It was also evaluated eight lines which carry these Rpp genes against five Asian soybean rust (ASR) isolates, in order to determine the likely range of resistance against ASR isolates differing in pathogenicity. The results indicated that a high level of resistance against various ASR isolates could be retained in lines carrying the three Rpp genes in susceptible genetic backgrounds, although minor influences of plant genetic background and ASR pathogenicity to the ASR resistance could occur. Thus, lines with the pyramided three Rpp genes should be effective against a complex pathogen population consisting of diverse Phakopsora pachyrhizi isolates.

Reproduction in Caribbean Fruit Flies: Comparisons between a Laboratory Strain and a Wild Strain

1977 ◽  
Vol 60 (2) ◽  
pp. 139 ◽  
Author(s):  
B. Mazomenos ◽  
J. L. Nation ◽  
W. J. Coleman ◽  
K. C. Dennis ◽  
R. Esponda
Keyword(s):  
Wild Strain ◽  
Laboratory Strain ◽  
Fruit Flies

scholarly journals Glycoproteins that exhibit extensive size polymorphisms in Dictyostelium discoideum.

Genetics ◽  
1989 ◽  
Vol 122 (1) ◽  
pp. 59-64 ◽  
Author(s):  
E Smith ◽  
A A Gooley ◽  
G C Hudson ◽  
K L Williams
Keyword(s):  
Linkage Group ◽  
Dictyostelium Discoideum ◽  
Allelic Variation ◽  
Surface Glycoprotein ◽  
Developmentally Regulated ◽  
Electrophoretic Variants ◽  
Cellular Slime Mould ◽  
Repeat Units ◽  
Group I ◽  
Cellular Slime

Abstract Electrophoretic variants which arise from amino acid substitutions, leading to charge differences between proteins are ubiquitous and have been used extensively for genetic analysis. Less well documented are polymorphisms in the size of proteins. Here we report that a group of glycoproteins, which share a common carbohydrate epitope, vary in size in different isolates of the cellular slime mould, Dictyostelium discoideum. One of these proteins, PsA, a developmentally regulated prespore-specific surface glycoprotein, has previously been shown to exist in three size forms due to allelic variation at the pspA locus on linkage group I. In this report, a second glycoprotein, PsB, which is also prespore specific but found inside prespore cells, is studied. PsB maps to linkage group II and exhibits at least four different sizes in the isolates examined. We propose that the size polymorphisms are the product of allelic variation at the pspB locus, due to differences in the number of repeat units.

scholarly journals THE EFFECT OF LEVEL OF HETEROZYGOSITY ON THE PERFORMANCE OF HYBRIDS BETWEEN ISOGENIC LINES OF BARLEY

Genetics ◽  
1976 ◽  
Vol 84 (4) ◽  
pp. 765-775
Author(s):  
A A Zali ◽  
R W Allard
Keyword(s):  
Complex Structure ◽  
Field Tests ◽  
Kernel Weight ◽  
Heading Time ◽  
Male Sterile ◽  
Planting Dates ◽  
Isogenic Lines ◽  
Marked Chromosome ◽  
Allelic State ◽  
Chromosome Segments

ABSTRACT Sixteen "isogenic" lines of Atlas 46 barley differing in one to four short chromosome segments, and 16 heterozygotes obtained by crossing these lines to male-sterile Atlas, were used to study the effect of level of heterozygosity on performance. In field tests conducted in four environments (two planting dates in two years) significant differences were found among the homozygous isogenic lines for the traits seed yield, kernel weight, tiller number, plant height, and heading time; thus each of the marked chromosome segments carries genes which, when homozygous, affect these quantitative characters. It was also found that heterozygotes produced more and heavier kernels and were taller and earlier than homozygotes but there was no clear indication that the degree of heterosis increased as the number of heterozygous segments increased from one to five. Degree of heterosis was, however, strongly affected by the environment, by allelic state at each segment (especially the segment marked by the two-row, six-row spike locus), and also by genotype for other marked segments. These results indicate that heterosis in barley has a more complex structure than can be adequately represented by simple models, such as the multiplicative model in which fitnesses are the product of fitnesses at individual loci, or threshold models in which optimum fitness is approached asymptotically as the number of heterozygous loci increases.

scholarly journals THE EFFECTS OF HETEROZYGOSITY CHANGES ON VIABILITY IN DROSOPHILA MELANOGASTER

Genetics ◽  
1972 ◽  
Vol 70 (4) ◽  
pp. 595-610
Author(s):  
Ray Moree
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Background ◽  
Laboratory Strain ◽  
Theoretical Expectation ◽  
Wild Type ◽  
Small Deviations ◽  
The Third ◽  
The Difference

ABSTRACT The viability effects of chromosomes from an old and from a new laboratory strain of D. melanogaster were studied in eight factorial combinations and at two heterozygosity levels. The combinations were so constructed that heterozygosity level could be varied in the third chromosomes of the carriers of a homozygous lethal marker, in the third chromosomes of their wild-type segregants, and in the genetic backgrounds of both. Excluding the effect of the marker and the exceptional outcomes of two of the combinations, and taking into account both large and small deviations from theoretical expectation, the following summary is given as the simplest consistent explanation of the results: 1) If total heterozygosities of two segregant types tend toward equality their viabilities tend toward equality also, whether background heterozygosity is high or low; if background heterozygosities is higher the tendency toward equality is slightly greater. 2) If total heterozygosity of two segregant types are unequal the less heterozygous type has the lower viability; the difference is more pronounced when background heterozygosity is low, less when it is high. 3) Differences between segregant viabilities are correlated with differences between the total heterozygosities of the two segregants; genetic background is effective to the extent, and only to the extent, that it contributes to the magnitude of this difference. This in turn appears to underlie, at least partly, the expression of a pronounced interchromosomal epistasis. Thus in this study viability is seen to depend upon both the quantity and distribution of heterozygosity, not only among the chromosomes of an individual but among the individuals of a given combination as well.

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