蛆症异蚤蝇减数分裂染色体观察

Observation on Meiotic Chromosomes of Megaselia scalaris ( Diptera: Phoridae)

以蛹精巢和卵巢组织为材料,采用空气干燥法制备染色体标本,Giemsa和硝酸银分别染色,对蛆症异蚤蝇Megaselia scalaris减数分裂染色体行为进行研究。结果表明:蛆症异蚤蝇的染色体数目n=3,由2条中着丝粒染色体和1条端着丝粒染色体组成;粗线期,第2条二价体具有较强的嗜银性,可能为性染色体;晚粗线期,第1条二价体的同源染色体之间出现一条细线,类似于联会复合体;终变期,第2条二价体形成环状结构;晚终变期,在3条二价体染色体臂上均产生条带,根据二价体着丝粒处是否成环可以将3条二价体分开。

Chromosome preparations were made from pupal testis and ovary of the Megaselia scalaris by air dry method. The morphological characteristics and behaviors of the chromosomes were studied by Giemsa and AgNO3 staining at various phases of meiosis. The results showed that chromosome number of Megaselia scalaris was three, including two metacentric and one telocentric. In pachytene, the 2^nd bivalent absorbed more sliver than the other two, which might be the sex chromo- somes. In late pachytene, a thin line emerged in the 1 ^st homomorphic chromosomes, which might be the synaptonemal com- plex （SC）. The 2^nd bivalent showed a ring like structure in diakinesis. In late diakinesis, some bands were appeared on all chromosome arms. The three bivalents could be distinguished by whether there was loop formation at the site of centromere.