scholarly journals Mitotic mapping ofSchizosaccharomyces pombe

1970 ◽  
Vol 16 (2) ◽  
pp. 127-144 ◽  
Author(s):  
Miguel Flores da Cunha
Keyword(s):  
Genetic Mapping ◽  
Fission Yeast ◽  
Genetic Markers ◽  
Mechanism Of Action ◽  
Genetic Identification ◽  
Crossing Over ◽  
Cell Divisions ◽  
Progressive Loss ◽  
Diploid Cells ◽  
Linkage Relationships

SUMMARYGenetic mapping by means of mitotic haploidization (induced by parafluoropkenylalanine) and mitotic crossing-over was carried out with the fission yeastSchizosaccharomyces pombe. Thirty-two different genetic markers were involved in this investigation; some meiotic linkage relationships had been previously reported (Leupold, Megnet) for 16 of these loci. Mitotic haploidization experiments resulted in the genetic identification of six chromosomes in the haploid complement.Furthermore, in an attempt to study the mechanism of action of parafluorophenylalanine (pFPA) on mitotic haploidization, pedigree analyses were performed by micromanipulation of diploid cells growing in the presence of pFPA. Haploid cells were detected after 40 hours of contact with the analogue and many lethal pedigree branches were observed. These observations seem to agree with Käfer's (1961) and Lhoa's (1968) suggestion that mitotic haploidization in Fungi is achieved by progressive loss of chromosomes throughout cell divisions.

scholarly journals Segregation of recombinant chromatids following mitotic crossing over in yeast.

Genetics ◽  
1991 ◽  
Vol 129 (2) ◽  
pp. 359-369 ◽  
Author(s):  
P Chua ◽  
S Jinks-Robertson
Keyword(s):  
Genetic Markers ◽  
Recombination Event ◽  
Strong Association ◽  
Mitotic Recombination ◽  
Crossing Over ◽  
Equal Frequency ◽  
Daughter Cells ◽  
Chromatid Segregation ◽  
Linkage Relationships ◽  
Chromosome Nondisjunction

Abstract It has long been assumed that chromatid segregation following mitotic crossing over in yeast is random, with the recombinant chromatids segregating to opposite poles of the cell (x-segregation) or to the same pole of the cell (z-segregation) with equal frequency. X-segregation events can be readily identified because heterozygous markers distal to the point of the exchange are reduced to homozygosity. Z-segregation events yield daughter cells which are identical phenotypically to nonrecombinant cells and thus can only be identified by the altered linkage relationships of genetic markers on opposite sides of the exchange. We have systematically examined the segregation patterns of chromatids with a spontaneous mitotic exchange in the CEN5-CAN1 interval on chromosome V. We find that the number of x-segregation events is equal to the number of z-segregations, thus demonstrating that chromatid segregation is indeed random. In addition, we have found that at least 5% of the cells selected for a recombination event on chromosome V are trisomic for this chromosome, indicating a strong association between mitotic recombination and chromosome nondisjunction.

scholarly journals GENETIC MAPPING IN SCHIZOSACCHAROMYCES POMBE BY MITOTIC AND MEIOTIC ANALYSIS AND INDUCED HAPLOIDIZATION

Genetics ◽  
1977 ◽  
Vol 87 (3) ◽  
pp. 471-489 ◽  
Author(s):  
Jürg Kohli ◽  
Herbert Hottinger ◽  
Peter Munz ◽  
Andre Strauss ◽  
Pierre Thuriaux
Keyword(s):  
Chromosome Number ◽  
Genetic Mapping ◽  
Schizosaccharomyces Pombe ◽  
Fission Yeast ◽  
Genetic Markers ◽  
Genetic Maps ◽  
Deficient Mutant ◽  
Linkage Groups ◽  
Meiotic Analysis ◽  
Haploid Chromosome Number

ABSTRACT The genetic maps of the fission yeast Schizosaccharomyces pombe were extended through the use of haploidization (spontaneous or induced by m-fluorophenylalanine), as well as by tetrad, random spore and mitotic analysis. A new diploidization method utilizing a meiosis-deficient mutant and improved haploidization techniques was employed. As a result of these and previous studies, 118 genetic markers have been assigned to 3 linkage groups. Centromere markers for all 3 chromosomes were identified and genetic maps containing a total of 71 genes were constructed. Our experiments indicate that 3 is very likely to be the haploid chromosome number of S. pombe.

scholarly journals Linkage relationships of markers on chromosome 17 of the house mouse

1975 ◽  
Vol 26 (2) ◽  
pp. 203-211 ◽  
Author(s):  
Graig Hammerberg ◽  
Jan Klein
Keyword(s):  
House Mouse ◽  
Chromosomal Region ◽  
Recombination Frequency ◽  
Genetic Distances ◽  
Chromosome 17 ◽  
Linkage Data ◽  
Crossing Over ◽  
The Right ◽  
Linkage Relationships ◽  
Important Marker

SUMMARYLinkage data for the following markers on chromosome 17 of the house mouse were obtained: centromere (marked by translocation R67), Brachyury (T), tufted (tf), H-2, and thin fur (thf). The markers were found to be arranged in that order in the genetic map and the combined genetic distances between individual markers were found to be as follows: Rb7…T, 4·5 cM; T…tf, 5·8 cM; tf…H-2, 5·0 cM; H-2…thf, 15·1 cM. The localization of the thf locus on the non-centromeric side of the H-2 complex provides an important marker for this arm of chromosome 17. The map distances in the centromeric portion of chromosome 17 changed drastically in the presence of various t factors. These factors strongly reduce the recombination frequency in the T…tf and tf…H-2 intervals and this crossing-over suppression is most likely responsible for the linkage disequilibrium between t and H-2 reported earlier. Recombinants involving a t chromosome but occurring to the right of the H-2 complex do not change the properties of t factors suggesting that all determinants responsible for the t phenotype are located in the chromosomal region between T and tf (H-2).

A LINKAGE STUDY INVOLVING TWO WHEAT-RYE TRANSLOCATION CHROMOSOMES

1969 ◽  
Vol 11 (1) ◽  
pp. 143-146 ◽  
Author(s):  
C. J. Driscoll ◽  
G. D. Patil
Keyword(s):  
Genetic Markers ◽  
Transmission Rate ◽  
Wheat Chromosome ◽  
Linkage Study ◽  
Linkage Test ◽  
Crossing Over ◽  
Complete Linkage ◽  
Transmission Rates ◽  
Chromosome Arm

Two wheat-rye translocation chromosomes involving the same wheat chromosome arm but different rye segments were subjected to a linkage test. Apparently no crossing over occurred between the non-homologous rye segments. The genetic markers possessed by these rye segments showed complete linkage in repulsion. The male transmission rates of the translocation chromosomes agree with those expected on the basis of the male transmission rate of each when competing with the normal wheat chromosome.

scholarly journals GENETIC MAPPING IN SACCHAROMYCES IV. MAPPING OF TEMPERATURE-SENSITIVE GENES AND USE OF DISOMIC STRAINS IN LOCALIZING GENES

Genetics ◽  
1973 ◽  
Vol 74 (1) ◽  
pp. 33-54
Author(s):  
R K Mortimer ◽  
D C Hawthorne
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Chromosome Number ◽  
Genetic Mapping ◽  
Genetic Markers ◽  
Genetic Maps ◽  
Temperature Sensitive ◽  
Yeast Saccharomyces Cerevisiae ◽  
Haploid Chromosome Number ◽  
Number Of Genes

ABSTRACT Through use of tetrad, random spore, trisomic, and mitotic analysis procedures a large number of genes, including 48 new genetic markers, were studied for their locations on the genetic maps of the yeast Saccharomyces cerevisiae. Eighteen new centromere linked genes were discovered and all but one was located on various ones of the 16 previously-established chromosomes. Five fragments of linked genes were also assigned to chromosomes; four were located on known chromosomes while the fifth determined one arm of a new chromosome. The experiments indicate that seventeen is likely to be the haploid chromosome number in this yeast. Most chromosomes have been established by genetic means to be metacentric and their genetic lengths vary from 5 cM to approximately 400 cM. Functionally-related sets of genes generally were found to be dispersed over the genome.

scholarly journals Genetic Mapping in Escherichia coli K-12 by Radiation-Induced Crossing-Over

1970 ◽  
Vol 103 (3) ◽  
pp. 601-606 ◽  
Author(s):  
M. Wann ◽  
S. K. Mahajan ◽  
T. H. Wood
Keyword(s):  
Escherichia Coli ◽  
Genetic Mapping ◽  
Crossing Over ◽  
Radiation Induced ◽  
K 12

scholarly journals The mechanism of fission yeast mating type interconversion: seal/replicate/cleave model of replication across the double-stranded break site at mat1.

Genetics ◽  
1991 ◽  
Vol 127 (3) ◽  
pp. 489-496 ◽  
Author(s):  
A J Klar ◽  
M J Bonaduce ◽  
R Cafferkey
Keyword(s):  
Fission Yeast ◽  
Mating Type ◽  
Dna Cleavage ◽  
Cell Lineage ◽  
Type Locus ◽  
Cis Acting ◽  
Cell Divisions ◽  
Break Site ◽  
A Cell ◽  
Cell Switches

Abstract The interconversion of cell type in the fission yeast, Schizosaccharomyces pombe, is initiated by a double-stranded break (DSB) found at the mating type locus (mat1). A heritable site- and strand-specific DNA "imprinting" event at mat1 was recently hypothesized to be required to make the mat1 locus cleavable, and the DSB was suggested to be produced one generation before the actual switching event. It is known that only one cell among four granddaughters of a cell ever switches, and the sister of the recently switched cell switches efficiently in consecutive cell divisions. The feature of consecutive switching creates a major difficulty of having to replicate chromosomes possessing the DSB. The mat1 cis-acting leaky mutation, called smt-s, reduces the level of the DSB required for switching and is shown here to be a 27-bp deletion located 50 bp away from the cut site. Determination of the pattern and frequency of switching of the mutant allele by cell lineage studies has allowed us to conclude the following: (1) the chromosome with the DSB is sealed and replicated, then one of the specific chromatids is cleaved again to generate switching-competent cells in consecutive cell divisions and (2) the smt-s mutation affects DNA cleavage and not the hypothesized DNA imprinting step.

Genetic identification of tissue of origin of cellular populations within the mouse placenta

Development ◽  
1985 ◽  
Vol 86 (1) ◽  
pp. 177-189
Author(s):  
J. Rossant ◽  
B. A. Croy
Keyword(s):  
Genetic Markers ◽  
Inner Cell Mass ◽  
Cell Mass ◽  
Complex Mixture ◽  
Placental Tissue ◽  
Genetic Identification ◽  
Blood Capillaries ◽  
Maternal Contribution ◽  
Foetal Blood

The mouse haemochorial placenta is a complex mixture of maternal cells and foetal trophectoderm and inner cell mass (ICM)-derived cells. The majority of the placental tissue is assumed to be trophoblast in origin but the exact extent and localization of the ICM and maternal contribution has not previously been determined. Using embryo transfer and reconstituted blastocyst techniques, combined with isozymal and in situ genetic markers, we have established that about 70% of the 13 to 15-day placenta is trophectoderm-derived, 30% is maternal in origin, and 4% develops from the ICM. Nearly all of the maternal contribution was confined to the spongiotrophoblast region and all of the ICM contribution was confined to the labyrinthine trophoblast region, where it formed the foetal blood capillaries and the endodermal sinuses. Using the same genetic markers, we showed that cell suspension techniques commonly used to produce ‘trophoblast’ cell preparations from placenta do not enrich for trophoblast, and, indeed, that collagenase, the preferred dissociation technique for cell viability, produced cell suspensions in which ICM and maternal cells were preferentially dissociated. No method for producing pure trophoblast populations has yet been found. Some unusually high ICM contributions to the placenta were found in reconstituted blastocyst experiments using ICMs isolated from early 3·5-day blastocysts, suggesting that these ICMs may have contributed to the trophectoderm layer of the blastocyst. These and other experiments suggest that the inner cell mass lineage may not be closed until some time after formation of the blastocyst.

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