Effects of B-chromosomes on recombination in cylinbrotettix obscurus (Leptysminae: Acrididae)

The grasshopper Cylindrotettix obscuras (Leptysminae: Acrididae) is polymorphic for a mitotically stable supernumerary isochromosome (Iso B) and a small, mitotically unstable B-chromosome (BT); both B-chromosomes significantly increase abnormal sperm formation, as determined by CONFALONIERI and BIDA...

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Autor principal: Colombo, P.C.
Formato: JOUR
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_00087114_v42_n1_p65_Colombo
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Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
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spelling todo:paper_00087114_v42_n1_p65_Colombo2023-10-03T14:07:45Z Effects of B-chromosomes on recombination in cylinbrotettix obscurus (Leptysminae: Acrididae) Colombo, P.C. The grasshopper Cylindrotettix obscuras (Leptysminae: Acrididae) is polymorphic for a mitotically stable supernumerary isochromosome (Iso B) and a small, mitotically unstable B-chromosome (BT); both B-chromosomes significantly increase abnormal sperm formation, as determined by CONFALONIERI and BIDAU (1986). In the present work 87 male individuals of C. obscurus from Misiones, Argentina, were analysed for total (T), proximal (P), interstitial (I) and distal (D) chiasma frequency with the aim of detecting effects of those B-chromosomes on recombination in this species. It was evident that the Iso B significantly raise T and P chiasma frequency; this effect was more evident in the carriers of two Iso B's. T and P chiasma frequencies descend in follicles with 1 BT with respect to 0 BT ones, and then increase gradually with 2, 3, 4 and 6 BT's; the regression of T and P on BT number was significant. However, the simultaneous presence of both B-chromosomes produces a marked decrease of T and P frequencies, yielding in some cases a high univalent frequency. The effects of both B-chromosomes are discussed in relation with other similar cases in closely related species. It is suggested that the rise of chiasma frequency in both cases would be due to reduced interference; on the contrary, the interaction effect would be due to asynapsis or desynapsis rather than to increased interference. © 1989 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_v42_n1_p65_Colombo
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
description The grasshopper Cylindrotettix obscuras (Leptysminae: Acrididae) is polymorphic for a mitotically stable supernumerary isochromosome (Iso B) and a small, mitotically unstable B-chromosome (BT); both B-chromosomes significantly increase abnormal sperm formation, as determined by CONFALONIERI and BIDAU (1986). In the present work 87 male individuals of C. obscurus from Misiones, Argentina, were analysed for total (T), proximal (P), interstitial (I) and distal (D) chiasma frequency with the aim of detecting effects of those B-chromosomes on recombination in this species. It was evident that the Iso B significantly raise T and P chiasma frequency; this effect was more evident in the carriers of two Iso B's. T and P chiasma frequencies descend in follicles with 1 BT with respect to 0 BT ones, and then increase gradually with 2, 3, 4 and 6 BT's; the regression of T and P on BT number was significant. However, the simultaneous presence of both B-chromosomes produces a marked decrease of T and P frequencies, yielding in some cases a high univalent frequency. The effects of both B-chromosomes are discussed in relation with other similar cases in closely related species. It is suggested that the rise of chiasma frequency in both cases would be due to reduced interference; on the contrary, the interaction effect would be due to asynapsis or desynapsis rather than to increased interference. © 1989 Taylor & Francis Group, LLC.
format JOUR
author Colombo, P.C.
spellingShingle Colombo, P.C.
Effects of B-chromosomes on recombination in cylinbrotettix obscurus (Leptysminae: Acrididae)
author_facet Colombo, P.C.
author_sort Colombo, P.C.
title Effects of B-chromosomes on recombination in cylinbrotettix obscurus (Leptysminae: Acrididae)
title_short Effects of B-chromosomes on recombination in cylinbrotettix obscurus (Leptysminae: Acrididae)
title_full Effects of B-chromosomes on recombination in cylinbrotettix obscurus (Leptysminae: Acrididae)
title_fullStr Effects of B-chromosomes on recombination in cylinbrotettix obscurus (Leptysminae: Acrididae)
title_full_unstemmed Effects of B-chromosomes on recombination in cylinbrotettix obscurus (Leptysminae: Acrididae)
title_sort effects of b-chromosomes on recombination in cylinbrotettix obscurus (leptysminae: acrididae)
url http://hdl.handle.net/20.500.12110/paper_00087114_v42_n1_p65_Colombo
work_keys_str_mv AT colombopc effectsofbchromosomesonrecombinationincylinbrotettixobscurusleptysminaeacrididae
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