The B-chromosomes of two species of Cylindrotettix (Leptysminae, Acrididae)

Twenty-four males of Cylindrotettix obscurus and ten of C. santarosae (Leptysminae, Acrididae) from Rio Claro, Brazil, were cytologically analysed. Both species are 2n = 23 ♂ (22+XO), all chromosomes being telocentric except for 4 acrocentric pairs of C. obscurus. Two different B-chromosomes were fo...

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Autores principales: Confalonieri, V.A., Bidau, C.J.
Formato: JOUR
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_00166707_v68_n2_p87_Confalonieri
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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_00166707_v68_n2_p87_Confalonieri2023-10-03T14:14:22Z The B-chromosomes of two species of Cylindrotettix (Leptysminae, Acrididae) Confalonieri, V.A. Bidau, C.J. Twenty-four males of Cylindrotettix obscurus and ten of C. santarosae (Leptysminae, Acrididae) from Rio Claro, Brazil, were cytologically analysed. Both species are 2n = 23 ♂ (22+XO), all chromosomes being telocentric except for 4 acrocentric pairs of C. obscurus. Two different B-chromosomes were found in C. obscurus: (1) a small, mitotically unstable telocentric (BT) and (2) a medium-sized, mitotically stable submetacentric (B1). B1 has a large pericentromeric heterochromatic portion and two distal euchromatic segments where both terminal associations and interstitial chiasmata are regularly formed producing a ring univalent at prophase I. B1 is almost certainly an iso-chromosome which has undergone a centromeric shift through pericentric inversion or centric transposition (heterochromatin duplication or deletion could also be the cause of arm inequality). In C. santarosae, a single male carried a small mitotically stable telocentric B-chromosome. Both B types of C. obscurus significantly increased the production of abnormal sperm (diploid, tetraploid and micro-spermatids) when compared to 0B individuals although their effects were differential: BT induced higher frequencies of microspermatids especially in those follicles with odd BT numbers, while in B1 carriers the increase was chiefly due to polyploid spermatids. None of the Bs of C. obscurus affected cell mean chiasma frequency nor the between-cell variance. The B of C. santarosae had no effect on abnormal sperm production but it probably increased cell mean chiasma frequency. © 1986 Dr W. Junk Publishers. Fil:Confalonieri, V.A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Bidau, C.J. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_00166707_v68_n2_p87_Confalonieri
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
description Twenty-four males of Cylindrotettix obscurus and ten of C. santarosae (Leptysminae, Acrididae) from Rio Claro, Brazil, were cytologically analysed. Both species are 2n = 23 ♂ (22+XO), all chromosomes being telocentric except for 4 acrocentric pairs of C. obscurus. Two different B-chromosomes were found in C. obscurus: (1) a small, mitotically unstable telocentric (BT) and (2) a medium-sized, mitotically stable submetacentric (B1). B1 has a large pericentromeric heterochromatic portion and two distal euchromatic segments where both terminal associations and interstitial chiasmata are regularly formed producing a ring univalent at prophase I. B1 is almost certainly an iso-chromosome which has undergone a centromeric shift through pericentric inversion or centric transposition (heterochromatin duplication or deletion could also be the cause of arm inequality). In C. santarosae, a single male carried a small mitotically stable telocentric B-chromosome. Both B types of C. obscurus significantly increased the production of abnormal sperm (diploid, tetraploid and micro-spermatids) when compared to 0B individuals although their effects were differential: BT induced higher frequencies of microspermatids especially in those follicles with odd BT numbers, while in B1 carriers the increase was chiefly due to polyploid spermatids. None of the Bs of C. obscurus affected cell mean chiasma frequency nor the between-cell variance. The B of C. santarosae had no effect on abnormal sperm production but it probably increased cell mean chiasma frequency. © 1986 Dr W. Junk Publishers.
format JOUR
author Confalonieri, V.A.
Bidau, C.J.
spellingShingle Confalonieri, V.A.
Bidau, C.J.
The B-chromosomes of two species of Cylindrotettix (Leptysminae, Acrididae)
author_facet Confalonieri, V.A.
Bidau, C.J.
author_sort Confalonieri, V.A.
title The B-chromosomes of two species of Cylindrotettix (Leptysminae, Acrididae)
title_short The B-chromosomes of two species of Cylindrotettix (Leptysminae, Acrididae)
title_full The B-chromosomes of two species of Cylindrotettix (Leptysminae, Acrididae)
title_fullStr The B-chromosomes of two species of Cylindrotettix (Leptysminae, Acrididae)
title_full_unstemmed The B-chromosomes of two species of Cylindrotettix (Leptysminae, Acrididae)
title_sort b-chromosomes of two species of cylindrotettix (leptysminae, acrididae)
url http://hdl.handle.net/20.500.12110/paper_00166707_v68_n2_p87_Confalonieri
work_keys_str_mv AT confalonieriva thebchromosomesoftwospeciesofcylindrotettixleptysminaeacrididae
AT bidaucj thebchromosomesoftwospeciesofcylindrotettixleptysminaeacrididae
AT confalonieriva bchromosomesoftwospeciesofcylindrotettixleptysminaeacrididae
AT bidaucj bchromosomesoftwospeciesofcylindrotettixleptysminaeacrididae
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