Effects of centric fusions on chiasma frequency and position in Leptysma Argentina (Acrididae: Orthoptera). II. Intra-and interchromosome effects
Leptysma argentina bears both a polymorphic centric fusion between telocentrics 3 and 6 (fusion 3/6) and a fixed one that produced the large metacentric 1 (fusion 1). A complex of phenomena, all of them leading to a general decrease in total recombination, are associated with fusion 3/6, namely: a)...
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todo:paper_00087114_v43_n2_p131_Colombo2023-10-03T14:07:45Z Effects of centric fusions on chiasma frequency and position in Leptysma Argentina (Acrididae: Orthoptera). II. Intra-and interchromosome effects Colombo, P.C. Leptysma argentina bears both a polymorphic centric fusion between telocentrics 3 and 6 (fusion 3/6) and a fixed one that produced the large metacentric 1 (fusion 1). A complex of phenomena, all of them leading to a general decrease in total recombination, are associated with fusion 3/6, namely: a) reduction of two independent linkage groups into one; b) intrachromosome adjustement of chiasma frequency to a minimal level, together with a strict distal localisation, and c) interchromosome effects, such as i) decrease in total mean cell chiasma frequency; ii) decrease in interstitial and proximal chiasma frequency, and iii) decrease in between-cell variance. On the other hand, chiasma distribution in the metacentric 1 seems to be irrestricted, et least when compared to the rigid localisation in the 3/6 metacentric of fusion 3/6 carriers. Therefore, it is suggested that the intrachromosome effects of fusion 3/6 on chiasma distribution are a consequence of adaptation to the polymorphic condition, although the possibility of a direct effect of the rearrangement cannot be excluded. Conversely, fusion 1 would not have passed through a long-lasting polymorphic situation (or else, it woud have suffered a second chiasma readjustament after definitive fixation). Finally, a model of chiasma formation in ‘Leptysma argentina’ is proposed, and the possibility is suggested that the interchromosome effects of fusion 3/6 are a result of increased chiasma interference. © 1990 Taylor & Francis Group, LLC. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_00087114_v43_n2_p131_Colombo |
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Universidad de Buenos Aires |
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I-28 |
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R-134 |
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Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| description |
Leptysma argentina bears both a polymorphic centric fusion between telocentrics 3 and 6 (fusion 3/6) and a fixed one that produced the large metacentric 1 (fusion 1). A complex of phenomena, all of them leading to a general decrease in total recombination, are associated with fusion 3/6, namely: a) reduction of two independent linkage groups into one; b) intrachromosome adjustement of chiasma frequency to a minimal level, together with a strict distal localisation, and c) interchromosome effects, such as i) decrease in total mean cell chiasma frequency; ii) decrease in interstitial and proximal chiasma frequency, and iii) decrease in between-cell variance. On the other hand, chiasma distribution in the metacentric 1 seems to be irrestricted, et least when compared to the rigid localisation in the 3/6 metacentric of fusion 3/6 carriers. Therefore, it is suggested that the intrachromosome effects of fusion 3/6 on chiasma distribution are a consequence of adaptation to the polymorphic condition, although the possibility of a direct effect of the rearrangement cannot be excluded. Conversely, fusion 1 would not have passed through a long-lasting polymorphic situation (or else, it woud have suffered a second chiasma readjustament after definitive fixation). Finally, a model of chiasma formation in ‘Leptysma argentina’ is proposed, and the possibility is suggested that the interchromosome effects of fusion 3/6 are a result of increased chiasma interference. © 1990 Taylor & Francis Group, LLC. |
| format |
JOUR |
| author |
Colombo, P.C. |
| spellingShingle |
Colombo, P.C. Effects of centric fusions on chiasma frequency and position in Leptysma Argentina (Acrididae: Orthoptera). II. Intra-and interchromosome effects |
| author_facet |
Colombo, P.C. |
| author_sort |
Colombo, P.C. |
| title |
Effects of centric fusions on chiasma frequency and position in Leptysma Argentina (Acrididae: Orthoptera). II. Intra-and interchromosome effects |
| title_short |
Effects of centric fusions on chiasma frequency and position in Leptysma Argentina (Acrididae: Orthoptera). II. Intra-and interchromosome effects |
| title_full |
Effects of centric fusions on chiasma frequency and position in Leptysma Argentina (Acrididae: Orthoptera). II. Intra-and interchromosome effects |
| title_fullStr |
Effects of centric fusions on chiasma frequency and position in Leptysma Argentina (Acrididae: Orthoptera). II. Intra-and interchromosome effects |
| title_full_unstemmed |
Effects of centric fusions on chiasma frequency and position in Leptysma Argentina (Acrididae: Orthoptera). II. Intra-and interchromosome effects |
| title_sort |
effects of centric fusions on chiasma frequency and position in leptysma argentina (acrididae: orthoptera). ii. intra-and interchromosome effects |
| url |
http://hdl.handle.net/20.500.12110/paper_00087114_v43_n2_p131_Colombo |
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AT colombopc effectsofcentricfusionsonchiasmafrequencyandpositioninleptysmaargentinaacrididaeorthopteraiiintraandinterchromosomeeffects |
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