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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| Formato: | Capítulo de libro |
| Lenguaje: | Inglés |
| Publicado: |
Kluwer Academic Publishers
1986
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| Acceso en línea: | Registro en Scopus DOI Handle Registro en la Biblioteca Digital |
| Aporte de: | Registro referencial: Solicitar el recurso aquí |
| Sumario: | 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. |
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| Bibliografía: | Gosálvez, J., Garcia de la Vega, C., Rufas, J. S. & López-Fernández, C., 1985. Unstable B-chromosomes producing abnormal spermatid nuclei in Sphingonotus coerulans (Orthoptera). Arch. Biol. 96 (in press); Hewitt, G.M., The integration of supernumery chromosomes into the orthopteran genome (1973) Cold Spring Harb. Symp. Quant. Biol., 38, pp. 183-194 Hewitt, G.M., Orthoptera (1979) Animal Cytogenetics 3. Insecta 1, , B., John, Borntraeger, Berlin-Stuttgart John, B., Hewitt, G.M., The B-chromosome system of Myrmeleotettix maculatus (Thunb.). 1. The mechanics (1965) Chromosoma, 16, pp. 548-578 John, B., Weissman, D.B., Cytogenetic components of reproductive isolation in Trimerotropis thalassica and T. occidentalis (1977) Chromosoma, 60, pp. 187-203 Jones, R.N., B chromosome systems in flowering plants and animal species (1975) Int. Rev. Cytol., 40, pp. 1-100 Jones, R.N., Rees, H., (1982) B chromosomes, , Academic Press, London-New York Müntzing, A., Accesory chromosomes (1975) Ann. Rev. Genet., 8, pp. 243-266 Nur, U., Mitotic instability leading to an accumulation of B-chromosomes in grasshoppers (1969) Chromosoma, 27, pp. 1-19 Rothfels, R., Procunier, W.A., B-chromosomes of Neopodismopsis abdominalis (Acrididae) (1975) Chromosoma, 52, pp. 137-148 Schroeter, G.L., Hewitt, G.M., The effects of supernumerary chromatin in three species of grasshoppers (1974) Can. J. Genet. Cytol., 16, pp. 285-296 Stephens, R.T., Bregman, A.A., The B-chromosome system of the grasshopper Melanoplus femur-rubrum (1972) Chromosoma, 38, pp. 297-311 Vilardi, J. C., 1985. Meiotic behaviour in a population of Dichroplus elongatus (Orthoptera: Acrididae). Caryologia (in press); White, M.J.D., (1973) Animal cytology and evolution, , 3rd Edit., Cambridge Univ. Press, London |
| ISSN: | 00166707 |
| DOI: | 10.1007/BF02424404 |