The relation between pairing preference and chiasma frequency in tetrasomics of rye

Genome ◽  
2004 ◽  
Vol 47 (1) ◽  
pp. 122-133 ◽  
Author(s):  
E Benavente ◽  
J Sybenga
Keyword(s):  
Secale Cereale ◽  
Chiasma Frequency ◽  
Active Sites ◽  
Chiasma Formation ◽  
Long Distance ◽  
Association Pattern ◽  
Chromosome 1R ◽  
Favorable Conditions ◽  
Pairing Initiation ◽  
Effective Pairing

The association pattern of marked tetrasomes of Secale chromosome 1R at meiotic first metaphase was analyzed. Two of the four chromosomes were identical with terminal C-bands at both arms; the other two were also identical but lacked C-bands and were homologous or homeologous with the first two. Four different types of heterozygotes for 1R were studied: (i) autotetraploid hybrids between genetic variants within Secale cereale subsp. cereale, (ii) tetraploid hybrids between subspecies of Secale cereale, (iii) tetraploid hybrids between species of Secale, and (iv) autotetrasomes of S. cereale in a wheat background. Earlier observations that heterozygous associations (banded with unbanded) had consistently higher chiasma frequencies than homozygous associations were extended and confirmed. To analyze this phenomenon more closely, the possible relations between this correlation and several other meiotic phenomena were studied. For this analysis, three genetically different autotetraploid hybrids within S. cereale were selected that differed with respect to the relation between pairing type and chiasma frequency. Special attention was given to different patterns of interference and other meiotic phenomena in the two chromosome arms of chromosome 1R. No relations between such phenomena and the relation between pairing type and chiasma frequency could be established. A hypothesis is formulated assuming that long-distance homologue attraction is concentrated in a limited number of sites and that in different genotypes, different patterns of active sites are present. Moderately weak attraction sites can pair with strong homologous sites under favorable genetic conditions, but two weak sites cannot. Then, heterozygotes have more effective pairing initiation and consequently chiasma formation than homozygotes. Under less favorable conditions, only strong sites are effective, and then, homozygotes pair better, but the chiasma frequency is lower. A model of the forces involved in homologue attraction is presented.Key words: autopolyploids, preferential pairing, chiasma frequency, homologue attraction, Secale.

Evidence of nonchiasmate bonds at metaphase I in inbred rye

1984 ◽  
Vol 26 (4) ◽  
pp. 409-414 ◽  
Author(s):  
M. C. Cermeño ◽  
J. Orellana ◽  
J. R. Lacadena
Keyword(s):  
Secale Cereale ◽  
Chiasma Frequency ◽  
Meiotic Pairing ◽  
Secale Cereale L ◽  
Chromosome 1R ◽  
Metaphase I

The loss of bound chromosome arms through early, middle, and late metaphase I has been analyzed in a plant of inbred rye (Secale cereale L.) heterozygous for a terminal heterochromatic C-band of the long arm of chromosome 1R. From the increase in the number of univalent pairs due to bound arm loss, and from the comparison between the frequencies of bound arms at metaphase I and recombinant chromosomes at anaphase I, it is concluded that some of the chromosome bonds appearing at metaphase I are actually nonchiasmate associations that can be considered as remnants of prophase pairing. Conclusions concerning recombination obtained solely from the analysis of chiasma frequency measured as bound arms may be invalid.Key words: inbred rye, C-heterochromatin, meiotic pairing, nonchiasmate bonds.

Relationship between pachytene synapsis, metaphase I associations, and transmission of 2B and 4B chromosomes in rye

Genome ◽  
2000 ◽  
Vol 43 (2) ◽  
pp. 232-239 ◽  
Author(s):  
Guillermo Jiménez ◽  
Silvia Manzanero ◽  
María J Puertas
Keyword(s):  
Secale Cereale ◽  
Maternal Effect ◽  
Chiasma Frequency ◽  
Transmission Rate ◽  
Chiasma Formation ◽  
B Chromosomes ◽  
Bivalent Formation ◽  
The Relationship ◽  
Variable Efficiency ◽  
Metaphase I

2B rye plants selected for high (H) or low (L) B transmission rate were studied at pachytene and metaphase I of meiosis to determine the relationship between synapsis, bivalents at metaphase I, and B transmission rate. The results show that the 2 B chromosomes (Bs) form bivalents at pachytene in both the H and L lines, whereas the frequency of bivalents at metaphase I is much higher in the H than in the L line. This demonstrates that B transmission is mainly related to the proper association of Bs at metaphase I, as well as that synapsis of the 2 Bs in the L line is normal, but the bivalent is not consolidated by a chiasma in most cases. Crosses were made between 2B plants of the H and L lines in all combinations (H × H, H × L, L × H, and L × L) to obtain 4B plants. Similarly, bivalent formation at pachytene and metaphase I was studied. The results show that 4B plants of the H × H and L × L classes differ significantly at pachytene and metaphase I since the former forms more bivalents. The heterozygous 4 Bs of the H × L and L × H classes show intermediate values. The relation H × H > H × L > L × H > L × L was consistently found for the variables transmission rate, bivalents at pachytene, bivalents at metaphase I, and B mean chiasma frequency. A maternal effect was also found. Our data suggest that there are two separate mechanisms acting upon synapsis and chiasma formation in H and L B chromosomes: (i) there is variable efficiency of the control of synapsis at early stages of meiosis; and (ii) there is variable efficiency of the control of the number of chiasmata. Key words: B chromosomes, synaptonemal complex, Secale cereale.

Synaptonemal complex formation and metaphase I configuration patterns in a translocation heterozygote of rye (Secale cereale)

Genome ◽  
1989 ◽  
Vol 32 (1) ◽  
pp. 72-81 ◽  
Author(s):  
J. H. de Jong ◽  
J. van Eden ◽  
J. Sybenga
Keyword(s):  
Complex Formation ◽  
Synaptonemal Complex ◽  
Secale Cereale ◽  
Chiasma Formation ◽  
Terminal Segment ◽  
Pachytene Nucleus ◽  
Synaptonemal Complexes ◽  
Synaptonemal Complex Formation ◽  
Chromosome 1R ◽  
Metaphase I

Four rye plants heterozygous for translocation 248, involving chromosomes 1R and 6R, were used for a comparative study of synaptonemal complex formation at midprophase I and chromosome configurations at metaphase I. Synaptonemal complexes were obtained with a cell-spreading technique and studied with electron microscopy. The total length of the synaptonemal complexes in the 28 analyzable pachytene nuclei varied considerably, both within and among plants. The variation of synaptonemal complex lengths of the bivalents in a nucleus was partly stage dependent; i.e., it was greater at early than at late pachytene. In all but one pachytene nucleus, pairing in the quadrivalent was regular, and the four pairing arms were usually easy to identify. Most noticeable was the variation of pairing saturation at the breakpoint of the quadrivalent. Pairing in the breakpoint region was delayed with respect to the pairing in the bivalents. Variation in the arm lengths of the quadrivalent was the result of incomplete and nonhomologous pairing at the breakpoint as well as differential contraction rates among chromosome segments. It was shown that the completion of delayed pairing throughout pachytene is mainly long-arm pairing. The actual breakpoint was therefore not in the middle of the unpaired segments, but more distal. The analysis of metaphase I nuclei revealed that chiasma frequency in this material was higher than in similar material used in former studies. When one of the translocation segments lacked a chiasma, this was in most cases the short translocated segment 1RS, the terminal segment of the satellite of chromosome 1R. Positive chiasma interference was demonstrated between the interstitial and exchanged segment in 1RS. This agreed with the observation of a negative correlation in extent of pairing between these two segments. Other interference phenomena, which have been described for this translocation in other material, remained undetected because of lack of variation in chiasma formation owing to high chiasma frequency.Key words: Secale cereale, meiosis, translocation, synaptonemal complex, metaphase I.

Synapsis and chiasma formation in a ditelo-substituted haploid of rye

Genome ◽  
1991 ◽  
Vol 34 (1) ◽  
pp. 109-120 ◽  
Author(s):  
J. H. de Jong ◽  
F. Havekes ◽  
A. Roca ◽  
T. Naranjo
Keyword(s):  
Synaptonemal Complex ◽  
Secale Cereale ◽  
Chiasma Formation ◽  
Chromosome Length ◽  
C Banding ◽  
Chromosome Associations ◽  
Synaptonemal Complex Formation ◽  
Chromosome 1R ◽  
In Cells ◽  
Metaphase I

Synapsis and chiasma formation were analyzed in a ditelo-substituted haploid of rye (Secale cereale), in which chromosome 1R was replaced by its telosomes. The study was made by comparing synaptonemal complex formation at early meiotic prophase I, chromosome associations at metaphase I, and recombinant chromosomes at anaphase I and prophase II. For the analysis of synaptonemal complexes, 41 nuclei at stages ranging from leptotene to early diplotene were selected. In the leptotene and early zygotene nuclei, numerous alignments of axial cores involving the same or different chromosomes were observed. Pairing initiation sites occurred at both interstitial and distal segments. Throughout zygotene the extent of pairing gradually increases, with values up to 84.8% at a stage that is morphologically comparable with late pachytene. Pairing-partner exchanges were frequently observed in zygotene nuclei, giving rise to multiple associations encompassing all or most of the chromosomes. In cells at metaphase I multivalents were very rare (2%), indicating elimination of most pairing-partner exchanges. In cells at metaphase I, anaphase I, and prophase II chromosome length, centromere position, and C-banding pattern enable the identification of the chromosomes 1RS, 1RL, 4R, 5R, and 6R, and the distinction of three metacentric chromosomes (RM1, RM2, and RM3). Metaphase I bonds were found to be nonrandomly distributed. Associations between the arms 4RL, 5RL, 6RL, and RM1L, all of them without telomeric C-bands, were more frequent than between the remaining arms. The bonds were mainly located at the distal parts of the chromosomes. The frequency of recombinant chromosomes at anaphase I or prophase II suggests that metaphase I bonds were true chiasmata.Key words: Secale cereale, haploid, synaptonemal complex, chiasmate bonds, C-banding.

A Demonstration of a 1:1 Correspondence Between Chiasma Frequency and Recombination Using a Lolium perenne/Festuca pratensis Substitution

Genetics ◽  
2002 ◽  
Vol 161 (1) ◽  
pp. 307-314 ◽  
Author(s):  
J King ◽  
L A Roberts ◽  
M J Kearsey ◽  
H M Thomas ◽  
R N Jones ◽  
...  
Keyword(s):  
Lolium Perenne ◽  
Chiasma Frequency ◽  
Chiasma Formation ◽  
Grass Species ◽  
Festuca Pratensis ◽  
Single Chromosome ◽  
Length Polymorphisms ◽  
Amplified Fragment Length Polymorphisms ◽  
Frequency Counts

Abstract A single chromosome of the grass species Festuca pratensis has been introgressed into Lolium perenne to produce a diploid monosomic substitution line (2n = 2x = 14). The chromatin of F. pratensis and L. perenne can be distinguished by genomic in situ hybridization (GISH), and it is therefore possible to visualize the substituted F. pratensis chromosome in the L. perenne background and to study chiasma formation in a single marked bivalent. Recombination occurs freely in the F. pratensis/L. perenne bivalent, and chiasma frequency counts give a predicted map length for this bivalent of 76 cM. The substituted F. pratensis chromosome was also mapped with 104 EcoRI/Tru91 and HindIII/Tru91 amplified fragment length polymorphisms (AFLPs), generating a marker map of 81 cM. This map length is almost identical to the map length of 76 cM predicted from the chiasma frequency data. The work demonstrates a 1:1 correspondence between chiasma frequency and recombination and, in addition, the absence of chromatid interference across the Festuca and Lolium centromeres.

Estimating meiotic chromosome pairing and recombination parameters in telocentric trisomics

Genome ◽  
2007 ◽  
Vol 50 (11) ◽  
pp. 1014-1028 ◽  
Author(s):  
J. Sybenga ◽  
H. Verhaar ◽  
D.G.A. Botje
Keyword(s):  
Gene Transfer ◽  
Chromosome Pairing ◽  
Genome Analysis ◽  
Meiotic Chromosome ◽  
Chiasma Formation ◽  
Chromosome Morphology ◽  
Test Material ◽  
Gene Localization ◽  
Maximum Information ◽  
Chromosome 1R

Telocentric trisomics (telotrisomics; one arm of a metacentric chromosome present in addition to two complete genomes) are used in theoretical studies of pairing affinities and chiasma formation in competitive situations and applied in genome analysis, gene localization, gene transfer, and breakage of close linkages. These applications require knowledge of the recombination characteristics of telotrisomics. Appropriate cytological and molecular markers and favorable chromosome morphology are not always available or applicable for quantitative analyses. We developed new mathematical models for extracting the maximum information from simple metaphase I observations. Two types of telotrisomics of the short arm of chromosome 1R of rye ( Secale cereale ), including several genotypes, were used as test material. In simple telotrisomics, pairing between morphologically identical complete chromosomes was more frequent than pairing between the telocentric and either of the normal chromosomes. In the telocentric substitution, morphologically identical telocentrics paired less frequently with each other than either one with the normal chromosome. Pairing partner switch was significant. Interaction between the two arms was variable. Variation within plants was considerable. Telotrisomics without markers are suitable for analyzing pairing preferences, for gene localization and gene transfer, and for breaking tight linkages, but less so for genome analysis.

scholarly journals Role of allosteric switches and adaptor domains in long-distance cross-talk and transient tunnel formation

2020 ◽  
Vol 6 (14) ◽  
pp. eaay7919
Author(s):  
Nandini Sharma ◽  
Navjeet Ahalawat ◽  
Padmani Sandhu ◽  
Erick Strauss ◽  
Jagannath Mondal ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Active Sites ◽  
Long Distance ◽  
Dynamic Interactions ◽  
Interface Control ◽  
Protein Energy ◽  
Catalytic Loop ◽  
Ammonia Tunnel ◽  
Dynamics Simulations

Transient tunnels that assemble and disassemble to facilitate passage of unstable intermediates in enzymes containing multiple reaction centers are controlled by allosteric cues. Using the 140-kDa purine biosynthetic enzyme PurL as a model system and a combination of biochemical and x-ray crystallographic studies, we show that long-distance communication between ~25-Å distal active sites is initiated by an allosteric switch, residing in a conserved catalytic loop, adjacent to the synthetase active site. Further, combinatory experiments seeded from molecular dynamics simulations help to delineate transient states that bring out the central role of nonfunctional adaptor domains. We show that carefully orchestrated conformational changes, facilitated by interplay of dynamic interactions at the allosteric switch and adaptor-domain interface, control reactivity and concomitant formation of the ammonia tunnel. This study asserts that substrate channeling is modulated by allosteric hotspots that alter protein energy landscape, thereby allowing the protein to adopt transient conformations paramount to function.

scholarly journals Mapping of resistance genes to brown rust in 1R chromosome of rye (Secale cereale L.)

2017 ◽  
Vol 38 (SI 2 - 6th Conf EFPP 2002) ◽  
pp. 588-589
Author(s):  
O.A. Baranova ◽  
A.P. Dmitriev ◽  
A.V. Voylocov ◽  
O.V. Solodukhina
Keyword(s):  
Resistance Genes ◽  
Secale Cereale ◽  
Segregation Analysis ◽  
Recombination Frequency ◽  
Brown Rust ◽  
Isozyme Locus ◽  
Secale Cereale L ◽  
Chromosome 1R

Five resistance genes to single-pustule isolates Nos. 12, 81,108 and 7 of brown rust were mapped on 1R chromosome of rye using two different F<sub>2</sub> populations. Under segregation analysis it was found linkage between genes controlling resistance to single-pustule isolates No. 12, 81, 108 and 25 and isozyme locus Prx7, which to be localized on chromosome 1R. The recombination frequencies are 0.32, 0.28, 0.29 and 0.32 correspondingly. Also we were found linkage between Prx7 and gene, controlling resistance to single-pustule isolate No. 7. Recombination frequency in this case was equal 0.10 and 0.29 in dependence on analyzing hybrids.

The Sec -1 locus on the short arm of chromosome 1R of rye ( Secale cereale )

Chromosoma ◽  
1996 ◽  
Vol 105 (5) ◽  
pp. 269-275 ◽  
Author(s):  
B. C. Clarke ◽  
Y. Mukai ◽  
R. Appels
Keyword(s):  
Secale Cereale ◽  
Chromosome 1R

The effect of genotype × cytoplasm interaction on meiotic behaviour of maize chromosomes

Genome ◽  
1992 ◽  
Vol 35 (4) ◽  
pp. 653-658 ◽  
Author(s):  
M. M. Kruleva ◽  
A. B. Korol ◽  
T. G. Dankov ◽  
V. G. Skorpan ◽  
I. A. Preygel
Keyword(s):  
Cytoplasmic Male Sterility ◽  
Male Sterility ◽  
Relative Stability ◽  
Chiasma Frequency ◽  
Chiasma Formation ◽  
Meiotic Behaviour ◽  
Male Sterile ◽  
Maize Hybrids ◽  
Male Sterile Cytoplasm ◽  
Cytoplasmic Sterility

The effect of four isogenic cytoplasmic types, normal, Salvador, Texas, and Charrua (the latter three causing male sterility), on the process of chiasma formation has been studied using two different maize hybrids. The cytoplasmic male sterility determinants have been shown to reduce the rate of interstitial exchanges per nucleus and per bivalent and the frequency of univalents. Increased variation between plants and relative stability of the intercellular variation within a plant have been observed for the parameters studied. It is concluded that the determinants of cytoplasmic sterility lower the probability of additional exchanges (relative to the obligate one) and reduce the frequency of premature disruption of one-exchange chromosome associations.Key words: maize, chiasma frequency, male sterile cytoplasm, univalent formation, genotype × cytoplasm interaction.

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