Differences in the meiotic pairing behavior of gonosomal heterochromatin between female and male Microtus agrestis: implications for the mechanism of heterochromatin amplification on the X and Y

2000 ◽  
Vol 91 (1-4) ◽  
pp. 253-260 ◽  
Author(s):  
A.P. Singh ◽  
S. Henschel ◽  
K. Sperling ◽  
V. Kalscheuer ◽  
H. Neitzel
Keyword(s):  
Microtus Agrestis ◽  
Meiotic Pairing ◽  
Pairing Behavior

Can abortive early homologous associations promote increased crossing-over in an adjacent rearranged segment?

Genome ◽  
1988 ◽  
Vol 30 (4) ◽  
pp. 469-472 ◽  
Author(s):  
Marjorie P. Maguire
Keyword(s):  
Crossing Over ◽  
Meiotic Pairing ◽  
Pairing Behavior ◽  
Chromosome Segments

Meiotic pairing behavior of rearranged chromosome segments is compared across an informative series of combinations. The question is raised whether the simplest explanation for some peculiar findings may include a sequence of synaptic precursor events at leptotene or zygotene, the course of which may eventually strongly affect crossover frequency.Key words: meiosis, synapsis, crossing-over, rearrangement.

scholarly journals PAIRING COMPETITION BETWEEN IDENTICAL AND HOMOLOGOUS CHROMOSOMES IN AUTOTETRAPLOID RYE. I. SUBMETACENTRIC CHROMOSOMES

Genetics ◽  
1985 ◽  
Vol 111 (4) ◽  
pp. 933-944
Author(s):  
J Orellana ◽  
J L Santos
Keyword(s):  
Genetic Control ◽  
Secale Cereale ◽  
Inbred Lines ◽  
Meiotic Pairing ◽  
Homologous Chromosomes ◽  
Partner Exchange ◽  
Pairing Behavior ◽  
Chromosome 1R ◽  
Heterochromatin Content

ABSTRACT Meiotic pairing preferences between identical and homologous but not identical chromosomes were analyzed in ten induced tetraploid/diploid chimaeral rye plants (Secale cereale) heterozygous for telomeric heerochromatin C-bands in both arms of chromosome 1R. These plants were the progeny of two crosses between only one plant of cv. Petkus, used as male, and two plants of the inbred lines E and R, respectively. Different pairing preferences for chromosome 1R were found: (1) between plants, (2) between chromosome arms within the same plant and (3) between bivalents and multivalents within the same plant. The possible influence in the preferences of several factors such as differences in C-heterochromatin content in the chromosomes analyzed, specific genetic control and independence in pairing behavior between both arms and partner exchange is discussed.

Molecular Cytogenetic Analysis and Meiotic Pairing Behavior of Progenies Originating from a Hexaploid Triticale (×Triticosecale, Wittmack) and Bread Wheat (Triticum aestivum, L.) Cross

2020 ◽  
Vol 160 (1) ◽  
pp. 47-56
Author(s):  
Aybeniz J. Aliyeva ◽  
András Farkas ◽  
Naib Kh. Aminov ◽  
Klaudia Kruppa ◽  
Márta Molnár-Láng ◽  
...  
Keyword(s):  
In Situ Hybridization ◽  
Chromosome Pairing ◽  
Addition Line ◽  
Meiotic Pairing ◽  
Hexaploid Triticale ◽  
Substitution Lines ◽  
Molecular Cytogenetic ◽  
Triticale Line ◽  
Pairing Behavior

The chromosomal constitution of 9 dwarf (D) and 8 semidwarf (SD) lines derived by crossing hexaploid Triticale line NA-75 (AABBRR, 2n = 6x = 42) with Triticumaestivum (AABBDD, 2n = 6x = 42) cv. Chinese Spring was investigated using molecular cytogenetic techniques: fluorescence in situ hybridization and genomic in situ hybridization. A wheat-rye translocation (T4DS.7RL), 8 substitution lines, and a ditelosomic addition line (7RSdt) were identified. In the substitution lines, 1, 2, or 4 pairs of wheat chromosomes, belonging to the A, B, or D genome, were replaced by rye chromosomes. Substitutions between chromosomes belonging to different wheat genomes [5B(5A), 1D(1B)] also occurred. The lines were genetically stable, each carrying 42 chromosomes, except the wheat-rye ditelosomic addition line, which carried 21 pairs of wheat chromosomes and 1 pair of rye telocentric chromosomes (7RS). The chromosome pairing behavior of the lines was studied during metaphase I of meiosis. The chromosome pairing level and the number of ring bivalents were different for each line. Besides rod bivalents, univalent and multivalent associations (tri- and quadrivalents) were also detected. The main goal of the experiment was to develop genetically stable wheat/Triticale recombinant lines carrying chromosomes/chromatin fragments originating from the R genome of Triticale line NA-75. Introgression of rye genes into hexaploid wheat can broaden its genetic diversity, and the newly developed lines can be used in wheat breeding programs.

Origin, structure, and behavior of a highly rearranged deletion chromosome 1BS-4 in wheat

Genome ◽  
2005 ◽  
Vol 48 (4) ◽  
pp. 591-597 ◽  
Author(s):  
Lili Qi ◽  
Bernd Friebe ◽  
Bikram S Gill
Keyword(s):  
Triticum Aestivum ◽  
Molecular Markers ◽  
Physical Mapping ◽  
Triticum Aestivum L ◽  
Distal Segment ◽  
Distal Region ◽  
Meiotic Pairing ◽  
Aegilops Species ◽  
Pairing Behavior ◽  
And Behavior

Wheat (Triticum aestivum L.) deletion (del) stocks are valuable tools for the physical mapping of molecular markers and genes to chromosome bins delineated by 2 adjacent deletion breakpoints. The wheat deletion stocks were produced by using gametocidal genes derived from related Aegilops species. Here, we report on the origin, structure, and behavior of a highly rearranged chromosome 1BS-4. The cytogenetic and molecular marker analyses suggest that 1BS-4 resulted from 2 breakpoints in the 1BS arm and 1 breakpoint in the 1BL arm. The distal segment from 1BS, except for a small deleted part, is translocated to the long arm. Cytologically, chromosome 1BS-4 is highly stable, but shows a unique meiotic pairing behavior. The short arm of 1BS-4 fails to pair with a normal 1BS arm because of lack of homology at the distal ends. The long arm of 1BS-4 only pairs with a normal 1BS arm within the distal region translocated from 1BS. Therefore, using the 1BS-4 deletion stock for physical mapping will result in the false allocation of molecular markers and genes proximal to the breakpoint of 1BS-4.Key words: Triticum aestivum, wheat, deletion–translocation, physical mapping.

A cytological study of intraspecific variation in Ceratopteris thalictroides

1979 ◽  
Vol 57 (16) ◽  
pp. 1694-1700 ◽  
Author(s):  
Leslie G. Hickok
Keyword(s):  
Spore Germination ◽  
Cytological Study ◽  
Meiotic Pairing ◽  
Spore Viability ◽  
Polymorphic Species ◽  
Structural Differences ◽  
Pairing Behavior ◽  
Ceratopteris Thalictroides ◽  
Low Levels ◽  
Intraspecific Hybrids

A cytological study of meiotic pairing behavior in intraspecific hybrids was undertaken utilizing seven different collections of Ceratopteris thalictroides. Two mutant gametophyte stocks with nonfunctional spermatozoids were utilized to facilitate the synthesis of intraspecific hybrids. Low levels of univalent and quadrivalent formation were found in most of the hybrids, indicating that some structural differences existed, but major pairing homologies were still evident. The fertility of hybrids ranged from 10 to 75% spore germination. One collection, from Hawaii, showed high levels of univalent formation and very low spore viability. In that this stock is both biologically and morphologically distinct, it should be given taxonomic recognition. The study, in general, is in agreement with the most recent taxonomic treatment of Ceratopteris in that it shows a significant amount of cytological variation within the polymorphic species C. thalictroides.

CYTOGENETICS OF PASPALUM CONSPERSUM AND ITS GENOMIC RELATIONSHIP WITH YELLOW-ANTHERED P. DILATATUM AND P. MALACOPHYLLUM

1976 ◽  
Vol 18 (4) ◽  
pp. 701-708 ◽  
Author(s):  
Byron L. Burson ◽  
Hugh W. Bennett
Keyword(s):  
Chromosome Number ◽  
Female Gametophyte ◽  
Embryo Sac ◽  
Warm Season ◽  
Meiotic Pairing ◽  
Genomic Relationship ◽  
Cytogenetic Investigation ◽  
Pairing Behavior ◽  
The Mean ◽  
The Relationship

Paspalum conspersum Schrad. ex Schult. is a leafy, robust, warm season perennial bunchgrass native to South America. A cytogenetic investigation was conducted to determine the feasibility of using the grass in an interspecific hybridization program. Four introductions were studied and each had a chromosome number of 2n = 4x = 40. During meiosis, the chromosomes paired primarily as bivalents with an occasional quadrivalent and a limited number of univalents. A study of megasporogenesis and embryo sac development revealed that the plants were sexual. Eighty hybrids were obtained from yellow-anthered P. dilatatum Poir, 2n = 4x = 40, × P. conspersum. Thirty of these were examined cytologically. All had a chromosome number of 2n = 4x = 40. Mean meiotic pairing was 19.87 I, 9.94 II, 0.12 III, and 0.004 IV. Because of segmental homology between the P. conspersum genomes, it was difficult to determine the relationship between the two species. Thus, P. conspersum was crossed with autotetraploid P. malacophyllum Trin., 2n = 4x = 40, to determine the amount of autosyndetic pairing between the P. conspersum chromosomes. One hybrid was obtained and it had a chromosome number of 2n = 4x = 40. The mean pairing behavior was 15.74 I, 12.07 II, and 0.008 IV. Ten of the bivalents were interpreted as autosyndetic pairing of the P. malacophyllum chromosomes and the remaining 2.07 bivalents as autosyndetic pairing of the P. conspersum chromosomes. These findings also show no homology between P. conspersum and P. malacophyllum chromosomes and suggest the species are not closely related. Since there is limited autosyndetic pairing between members of the P. conspersum genomes, data from the P. dilatatum × P. conspersum hybrids indicate the two species have at least one common genome. Megasporogenesis was normal in both groups of hybrids. However, in the P. dilatatum × P. conspersum hybrids, the sexual tissue generally deteriorated, resulting in complete abortion of the female gametophyte. In the P. conspersum × P. malacophyllum hybrid, about 90% of the mature ovules had sexual embryo sacs. However, in the remaining ovules there was either deterioration of the sexual tissue or other abnormalities.

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