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).

High resolution map around the vrs1 locus controlling two- and six-rowed spike in barley, Hordeum vulgare

Genome ◽  
1999 ◽  
Vol 42 (2) ◽  
pp. 248-253 ◽  
Author(s):  
Takao Komatsuda ◽  
Wenbin Li ◽  
Fumio Takaiwa ◽  
Seibi Oka
Keyword(s):  
Hordeum Vulgare ◽  
Mapping Population ◽  
Recombination Frequency ◽  
Linkage Study ◽  
Linkage Data ◽  
Published Data ◽  
Crossing Over ◽  
Lateral Spikelet ◽  
Significant Difference ◽  
High Resolution Map

The vrs1 (formerly v) locus in the long arm of chromosome 2H controls lateral spikelet development in barley. The vrs1 locus was mapped by backcross-derived lines that consisted of 373 BC7F1 plants and 278 BC6F2 plants. The linkage study indicated that MWG801, CMNA-38/700, cMWG699, vrs1 and MWG865 exist in the order listed, with map distances of 3.1, 0.4, 0.1, and 0.9 centimorgans (cM), respectively. Recombination in female and male meiocytes showed no significant difference within this region. In a neighboring region between MWG865 and MWG503, the recombination frequency was higher in female than male meiocytes in one mapping population. The combined linkage data obtained from this study were compared with published data, and genotype-specific suppression of crossing-over was not evident in the vrs1 region.Key words: vrs1 locus (two- vs. six-rowed), molecular marker, recombination, backcross, Hordeum vulgare.

scholarly journals Sex-related differences in crossing over in Caenorhabditis elegans.

Genetics ◽  
1990 ◽  
Vol 126 (2) ◽  
pp. 355-363
Author(s):  
M C Zetka ◽  
A M Rose
Keyword(s):  
Caenorhabditis Elegans ◽  
Maternal Age ◽  
Elevated Temperatures ◽  
Recombination Frequency ◽  
Paternal Age ◽  
Crossing Over ◽  
Nematode Caenorhabditis Elegans ◽  
Male Recombination ◽  
Group I ◽  
The Right

Abstract In the nematode Caenorhabditis elegans, hermaphrodite recombination has been characterized and is the basis of the genetic map used in this organism. In this study we have examined male recombination on linkage group I and have found it to be approximately one-third less than that observed in the hermaphrodite. This decrease was interval-dependent and nonuniform. We observed less recombination in the male in 5 out of 6 intervals examined, and no observable difference in one interval on the right end of LG I. Hermaphrodite recombination frequencies are the result of recombination in two germlines; oocyte and hermaphrodite spermatocytes. We have measured recombination in the oocyte and have found it to be approximately twofold lower than that calculated for hermaphrodite spermatocytes and not significantly different from the male spermatocyte frequency. Thus, recombination frequencies appear to be a function of gonad physiology rather than the sex of the germline. Evidence from experiments examining the effect of karyotype on recombination in males sexually transformed by the her-1 mutation into XO hermaphrodites (normally XX), suggests the sexual phenotype rather than genotype determines the recombination frequency characteristic of a particular sex. Hermaphrodite recombination is known to be affected by temperature, maternal age, and the rec-1 mutation. We have examined the effect of these parameters on recombination in the male and have found male recombination frequency increased with elevated temperatures and in the presence of Rec-1, and decreased with paternal age.

Genetic Recombination in Coprinus

1970 ◽  
Vol 6 (3) ◽  
pp. 669-678
Author(s):  
B. C. LU
Keyword(s):  
Fruiting Body ◽  
Temperature Effects ◽  
Cold Shock ◽  
Genetic Recombination ◽  
Recombination Frequency ◽  
Temperature Treatment ◽  
Sensitive Period ◽  
Crossing Over ◽  
Synaptinemal Complex ◽  
Before And After

The frequency of genetic recombination in Coprinus lagopus may be modified by heat and cold shock. By removal of samples from a fruiting body before and after temperature treatment, it is possible to study the ultrastructure of chromosomes at the time recombination frequency (between den+ x +me-1) can be modified. The sensitive period for temperature effects and, therefore, probably the time of crossing over, commences with the formation of the synaptinemal complex (S.C.) and ends with its disappearance, i.e. during the entire existence of the S.C. It is concluded that recombination is an event subsequent to the formation of the S.C. and is independent of the process of its formation. It is suggested that the event takes place at the synaptic centre.

Further linkage data on the albino chromosome of the house-mouse

1936 ◽  
Vol 33 (2) ◽  
pp. 255-265 ◽  
Author(s):  
Hans Grüneberg
Keyword(s):  
House Mouse ◽  
Linkage Data

Segmental Neurofibromatosis Follows Blaschko's Lines or Dermatomes Depending on the Cell Line Affected: Case Report and Literature Review

2004 ◽  
Vol 8 (5) ◽  
pp. 353-356
Author(s):  
Fara P. Redlick ◽  
James C. Shaw
Keyword(s):  
Schwann Cells ◽  
Clinical Manifestations ◽  
Neurofibromatosis Type ◽  
Cell Types ◽  
Genetic Mutation ◽  
The Body ◽  
Chromosome 17 ◽  
Medline Search ◽  
Characteristic Features ◽  
The Right

Background: Segmental neurofibromatosis type 1 (NF-1) has the characteristic features of generalized NF-1 but is isolated to a particular segment of the body. Segmental NF-1 results from a postzygotic mutation during embryogenesis in the NF-1 gene on chromosome 17. The embryologic timing of the mutation and cell types affected predict the clinical phenotype. Objective: We present a case of a 52-year-old woman with segmental neurofibromas isolated to the right cheek and neck. We review the recent literature on the genetic and cellular differences between the various clinical manifestations of segmental NF-1. Methods: A MEDLINE search for cases of segmental neurofibromatosis was conducted. Results: In patients with segmental NF-1 presenting as neurofibromas-only, the distribution follows a neural distribution in dermatomes because the genetic mutation appears to be limited to Schwann cells. In patients with pigmentary changes only, the NF-1 mutation has been shown to occur in fibroblasts and the distribution tends to follow the lines of Blaschko. Conclusion: Our patient's neurofibromas were secondary to a postzygotic mutation in the NF-1 gene of neural crest–derived cells. This mutation most likely occurred later in embryogenesis in cells that had already differentiated to Schwann cells and were committed to the dermatomal distribution of the right neck and cheek region (C2).

scholarly journals Inheritance and Linkage Relationships of Isozymes in Easter Cactus

1998 ◽  
Vol 123 (1) ◽  
pp. 98-103
Author(s):  
Maureen C. O'Leary ◽  
Thomas H. Boyle
Keyword(s):  
Interspecific Hybrids ◽  
Triosephosphate Isomerase ◽  
Recombination Frequency ◽  
Polyacrylamide Gel Electrophoresis ◽  
Interspecific Crosses ◽  
Germplasm Collections ◽  
Segregation Ratios ◽  
Isozyme Loci ◽  
Linkage Relationships ◽  
Aberrant Segregation

Polyacrylamide gel electrophoresis was used to study inheritance and linkage of isozymes in Easter cactus (Hatiora species and interspecific hybrids). Five isozyme systems were analyzed: aspartate aminotransferase (AAT), glucose-6-phosphate isomerase (GPI), malate dehydrogenase (MDH), phosphoglucomutase (PGM), and triosephosphate isomerase (TPI). F1, F2, BC1, and S1 progeny were used for inheritance studies. Six polymorphic loci (Aat-1, Gpi-1, Mdh-1, Pgm-1, Pgm-2, and Tpi-2) were identified. Aat-1 and Pgm-1 were linked (recombination frequency = 26% ± 7%), but the other isozyme loci assorted independently. Aberrant segregation ratios were observed in at least one segregating family for all six isozyme loci. We hypothesize that segregation distortion was due to linkage between isozyme loci and other genes subject to pre- or postzygotic selection. The existence of five additional isozyme loci (Aat-2, Gpi-2, Mdh-2, Mdh-3, and Tpi-1) was inferred from segregation patterns and by comparison of isozyme profiles from phylloclades and pollen. These isozyme loci may prove useful for confirming hybridity in intra- and interspecific crosses, determining parentage of cultivars, and assessing genetic diversity in germplasm collections.

scholarly journals Extremism and Intelligence

2020 ◽  
Vol 2 (3) ◽  
pp. 15
Author(s):  
Julian Richards
Keyword(s):  
Social Media ◽  
Social Movements ◽  
Liberal Democracy ◽  
Cutting Edge ◽  
Crossing Over ◽  
Allocation Of Resources ◽  
Transnational Social Movements ◽  
Intelligence Agencies ◽  
Difficult Challenge ◽  
The Right

Contemporary extremist threats encompass a widening spectrum, whereby long-standing threats are supplemented by the stubborn persistence of historical threats, and by the emergence of new threats and Violent Transnational Social Movements (VTSMs). For security and intelligence agencies, the management challenges posed by the evolving picture are complex and multi-faceted. Probably the most difficult challenge is that of prioritisation and the allocation of resources across the spectrum of investigation. Other challenges include those of recruiting and retaining staff with the right cutting-edge skills, especially in such fields of social media exploitation; and a fundamental definitional question of how to define some of the newly-emerging threats, avoiding questions of surveillance crossing-over into inappropriate suppression of legitimate dissent in a liberal democracy.

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