title: Q-, C-, and G-banding patterns in the germ-line and somatic chromosomes of Miastor sp. (Diptera: Cecidomyidae).
abstract: Q-, C-, and G-banding patterns are described for the germ-line and somatic chromosomes of Miastor sp. The chromosome number in the germ line is 36, which is 3 less than that previously reported for the same cultured line 18 years ago. There are 8 chromosome groups: 8 large acrocentrics, 11 large and medium submetacentrics, 4 medium metacentrics, 4 medium subtelocentrics, 6 medium telocentrics, one medium acrocentric, one small submetacentric, and one small telocentric. All 8 large acrocentrics have a Q-band and an interstitial C-band in the short arm, suggesting that these chromosomes are at least partially homologous (or homeologous) and that the germ line originally was polyploid. Only one other germ-line chromosome, the small submetacentric, has a Q-band and an interstitial C-band. In somatic cells there are 8 chromosomes, 28 chromosomes having been eliminated during early cleavage. Three of the four pairs of somatic chromosomes are heteromorphic, despite the indications of a polyploid origin of the germ-line chromosomes and despite the presence of somatic pairing. Furthermore, there is a great deal of restriction on which chromosomes are retained in somatic cells, and it may be that the same 8 chromosomes are retained by all embryos. The G-banding pattern is not as clear as the other two banding patterns. The findings are discussed in relation to observations in other cecidomyids, and a model for the evolution of the chromosome system of Miastor is presented.
mesh_terms: D000818:Animals; D001399:Azure Stains; D005075:Biological Evolution; D002875:Chromosomes / Q000648:ultrastructure*; D004175:Diptera / Q000648:ultrastructure*; D005854:Germ Cells / Q000648:ultrastructure; D006570:Heterochromatin / Q000648:ultrastructure; D007621:Karyotyping; D010312:Parthenogenesis; D011123:Polyploidy; D011796:Quinacrine
chemical_list: D001399:Azure Stains; D006570:Heterochromatin; D011796:Quinacrine