Satellite-association frequency and rDNA content of a double-satellited chromosome

1976 ◽  
Vol 31 (1) ◽  
pp. 113-115 ◽  
Author(s):  
A. S. Henderson ◽  
K. C. Atwood
Keyword(s):  
Satellite Association ◽  
Association Frequency

CHROMOSOMAL SATELLITE ASSOCIATION

The Lancet ◽  
1967 ◽  
Vol 289 (7489) ◽  
pp. 567
Author(s):  
M.H. Khan ◽  
H. Martin
Keyword(s):  
Satellite Association

Ag staining of the nucleolus organizer (NO) and its relationship to satellite association

1978 ◽  
Vol 44 (1) ◽  
pp. 71-77 ◽  
Author(s):  
A. de Capoa ◽  
M. Ferraro ◽  
F. Menendez ◽  
C. Mostacci ◽  
F. Pelliccia ◽  
...  
Keyword(s):  
Nucleolus Organizer ◽  
Satellite Association

Mathematical models for estimating preferential pairing and recombination in triploid hybrids

Genome ◽  
1988 ◽  
Vol 30 (5) ◽  
pp. 745-757 ◽  
Author(s):  
J. Sybenga
Keyword(s):  
Mathematical Models ◽  
Genetic Factors ◽  
Triploid Hybrid ◽  
Preferential Pairing ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Association Frequency ◽  
Ring Bivalents ◽  
Normal Pairing ◽  
Pairing Behaviour

Different mathematical models for estimating pairing and recombination parameters for triploid hybrids with two-armed chromosomes are discussed. In most models all information on preferential pairing is contained in the ratio of trivalents and ring bivalents and can be estimated independently of the chiasmate association frequencies in the two chromosome arms. The single degree of freedom available only permits the estimation of ranges of the three possible pairing relations between the three genomes. Alternatively, a single parameter can be estimated when additional assumptions are made. When the ratio r between the frequencies of trivalents and ring bivalents, independent of arm length differences and with a theoretical maximum of 2, is about 1, the ranges of the frequencies of the three pairing combinations are wide. When r becomes smaller than 1, very soon the ranges become limited to values where one of the three is relatively large and positive and the other two negative and varying between equal to very different, depending on slight changes in the first. When the frequency of open bivalents is relatively high and the frequency of univalents low, there most probably is a difference in chiasmate association frequency between the two arms of the average chromosome and this difference can be quantified. When the number of univalents is only slightly higher than expected on the basis of the number of open bivalents, the reason may be that (quantifiably) more chiasmata are formed after bivalent pairing than after trivalent pairing within certain ranges of r, and certain ranges of the average chiasmate association frequency. When the excess of univalents is larger, this is best explained by a failure of entire chromosomes to find each other. This degree of pairing failure can be estimated. All models have been applied to the triploid hybrid between allotetraploid Trifolium repens and diploid T. nigrescens. Assuming that the two genomes of T. repens do not pair, which cannot be demonstrated with certainty, the two genomes pair with the nigrescens genome with frequencies of 0.828 and 0.171, respectively. Introgression then occurs into either genome but not with the same frequency. If the repens genomes pair, this would be caused by either genetic factors disturbing the normal pairing behaviour or the absence of strict homologues. Then the relative pairing frequency between T. nigrescens and one of the T. repens genomes would be 0.838 and on an average 0.081 between the two other combinations, with a possibly considerable but unknown difference. The high average chiasmate arm association frequency (0.650) suggests that affinity between the pairing genomes is not very low. The average two arms do not differ in chiasma frequency.Key words: triploid hybrids, preferential pairing, recombination, mathematical models, Trifolium.

Random single chromatid and nonrandom double chromatid type segregation of human acrocentric chromosomes in BrdU-labeled mitoses

1984 ◽  
Vol 26 (2) ◽  
pp. 137-140 ◽  
Author(s):  
S. Chemitiganti ◽  
R. S. Verma ◽  
S. Ved Brat ◽  
H. Dosik
Keyword(s):  
Human Leukocytes ◽  
Satellite Association ◽  
Chromatid Segregation ◽  
Random Segregation ◽  
Acrocentric Chromosomes ◽  
Single Chromatid ◽  
Cis And Trans

Chromatid segregation was analyzed using satellite association of 5-bromodeoxyuridine (BrdU) differentially stained acrocentric chromosomes of human leukocytes. Data were classified into cis and trans configurations in second and third division cycles. It was found that single chromatid types have random segregation (1:1) while nonrandom segregation was noted for double chromatid types. The nonrandom segregation hypothesis of earlier investigators needs to be reexamined.Key words: chromatid segregation, BrdU, mitosis, acrocentric.

scholarly journals Satellite association and trisomy in thyrotoxicosis.

1968 ◽  
Vol 5 (1) ◽  
pp. 45-47 ◽  
Author(s):  
H R Nankin ◽  
J Sode ◽  
M F Ball
Keyword(s):  
Satellite Association

scholarly journals A Cytogenetic Study on the Efficacy of Chyawanprash Awaleha as an Antioxidant in Oral Premalignant Cancer

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
A. N. Uma ◽  
Dhananjay S. Kotasthane
Keyword(s):  
Dna Damage ◽  
Precancerous Lesions ◽  
Cytogenetic Study ◽  
Mean Difference ◽  
Betel Quid ◽  
Satellite Association ◽  
Betel Quid Chewing ◽  
Group 2 ◽  
Oral Precancerous Lesions ◽  
Group 1

Background. Chyawanprash awaleha (Cp) is an Ayurvedic rasayana formulation and is used as a genoprotective agent. Objective. The present cytogenetic study has been done to investigate the efficacy of Cp against betel quid chewers suffering from oral precancerous lesions through satellite association (SA) assay. Materials and Methods. The frequency of SA was analyzed in 21 betel quid chewing oral precancerous lesions patients and then they were divided into 2 groups. Group 1 consisted of 15 patients, advised to quit betel quid chewing and fed with 20 gms of Cp, twice a day for three months. Group 2 consisted of 6 patients, who refused Cp feed but accepted to quit betel quid chewing. At the end of three months, both groups were assessed cytogenetically. Results. The frequency of SA was statistically significant in both groups, but an elevated mean difference was observed more in Group 1 than in Group 2. Conclusion. The study indicates that betel quid cessation reduces the effect of DNA damage in oral precancerous lesions. But the increased mean difference in SA in Group 1 compared to Group 2 clearly indicates that Cp can further minimize the genotoxic effect caused by mutagenic agents present in betel quid.

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