Rocha Marla Piumbini, Pompolo Silvia Das Graças, Dergam Jorge Abdala, Fernandes Anderson, Campos Lucio Antonio De Oliveira
Departamento de Biologia Geral, Universidade Federal de Viçosa, MG, Brazil.
Hereditas. 2002;136(1):19-27. doi: 10.1034/j.1601-5223.2002.1360104.x.
We analyzed patterns of heterochromatic bands in the Neotropical stingless bee genus Melipona (Hymenoptera, Meliponini). Group I species (Melipona bicolor bicolor, Melipona quadrifasciata, Melipona asilvae, Melipona marginata, Melipona subnitida) were characterized by low heterochromatic content. Group II species (Melipona capixaba, Melipona compressipes, Melipona crinita, Melipona seminigra fuscopilosa e Melipona scutellaris) had high heterochromatic content. All species had 2n = 18 and n = 9. In species of Group I heterochromatin was pericentromeric and located on the short arm of acrocentric chromosomes, while in Group II species heterochromatin was distributed along most of the chromosome length. The most effective sequential staining was quinacrine mustard (QM)/distamycin (DA)/chromomycin A3(CMA3)/4-6-diamidino-2-phenylindole (DAPI). Heterochromatic and euchromatic bands varied extensively within Group I. In Group II species euchromatin was restricted to the chromosome tips and it was uniformly GC+. Patterns of restriction enzymes (EcoRI, DraI, HindIII) showed that heterochromatin was heterogeneous. In all species the first pair of homologues was of unequal size and showed heteromorphism of a GC+ pericentromeric heterochromatin. In M. asilvae (Group I) this pair bore NOR and in M. compressipes (Group II) it hybridized with a rDNA FISH probe. As for Group I species the second pair was AT+ in M. subnitida and neutral for AT and GC in the remaining species of this group. Outgroup comparison indicates that high levels of heterochromatin represent a derived condition within Melipona. The pattern of karyotypic evolution sets Melipona in an isolated position within the Meliponini.
我们分析了新热带无刺蜂属（膜翅目，无刺蜂科）的异染色质带模式。第一组物种（双色无刺蜂双色亚种、四带无刺蜂、阿西尔无刺蜂、缘边无刺蜂、亚暗无刺蜂）的特征是异染色质含量低。第二组物种（卡皮克萨巴无刺蜂、压缩无刺蜂、多毛无刺蜂、半黑无刺蜂棕毛亚种和盾无刺蜂）具有高异染色质含量。所有物种的染色体数目均为2n = 18，单倍体数目为n = 9。在第一组物种中，异染色质位于着丝粒周围，位于近端着丝粒染色体的短臂上，而在第二组物种中，异染色质沿染色体长度的大部分分布。最有效的顺序染色是喹吖因芥子（QM）/偏端霉素（DA）/放线菌素A3（CMA3）/4,6-二脒基-2-苯基吲哚（DAPI）。第一组内异染色质带和常染色质带差异很大。在第二组物种中，常染色质局限于染色体末端，并且均为GC+。限制性内切酶（EcoRI、DraI、HindIII）模式表明异染色质是异质的。在所有物种中，第一对同源染色体大小不等，显示出GC+着丝粒周围异染色质的异形性。在阿西尔无刺蜂（第一组）中，这一对带有核仁组织区，在压缩无刺蜂（第二组）中，它与rDNA FISH探针杂交。至于第一组物种，第二对在亚暗无刺蜂中是AT+，在该组其余物种中对AT和GC呈中性。外群比较表明，高水平的异染色质代表了无刺蜂属内的一种衍生状态。核型进化模式使无刺蜂属在无刺蜂科中处于孤立的位置。
