伍氏游仆虫(Euplotes woodruffi)大核原基中的多线染色体  

POLYTENE CHROMOSOMES IN THE CILIATE EUPLOTES WOODRUFFI

作　　者：王哈利 陈阅增 

机构地区：[1]北京大学生物学系,北京100871

出　　处：《动物学报》1995年第1期82-87,共6页ACTA ZOOLOGICA SINICA

基　　金：高校博士点科研基金资助

摘　　要：用染色体铺展技术，光镜和透射电镜技术，和有色光分光光度计量术等观察了伍氏游仆虫在２３—２５℃培养液中接合后体大核原基多线染色体的发生、发展及碎解的全过程。在发育到４—５小时的接合后体中，球形的大核原基中开始出现染色体。此时的染色体大多为颗粒状，有些染色体已从颗粒状延长而成平均３μｍ的短杆。染色体数初步计算为２ｎ＝７０—９０。约经２０分钟，染色体延长并多线化。再过约５—６小时，多线染色体发育到最高峰。细长丝状的多线染色体上带和间带分化明显。有些染色体的末端有扇面状或小球形结构。各别染色体还显示了类似于着丝点的结构。这一时期的大核原基体积最大，ＤＮＡ含量达到最高值，接近营养大核ＤＮＡ含量的一半。然后多线染色体碎解，各多线染色体为纤维膜横割为大小不一的片段，ＤＮＡ含量也随之降至最高值的１／１０。By means of optical and TEM, the development of the macronuclear anlage and the structure of the polytene chromosomes of the exconjugants of Euplotes woodruffi, were investigated. The macronuclear anlage in the young exconjugants newly separated from the mating pairs was homogeneous and only faintly stained with Feulgen's reagent or carbol- fuchsin. In 4-5 hours exconjugants, granular chromosomes appeared which elongated soon into vermiform rodlets. The number of chromosomes was counted as 2n = 70-90. After about 20 minutes, bands of various sizes began to appear in all the chromosomes in the anlage. It seemed that polytenization and despiralization occurred simultaneously in the chro- mosomes. In exconjugants of more than 5 hours old, chromosomes extended to over 60 μm in length and showed clearly differentiated bands and interbands. Fan-shaped and node-like ends of some chromosomes were seen. Densely stained spherical bodies, believed to be centromeres, were also present in some of the preparations. When the anlage arrived at the largest size with polytene chromosomes densely packed in it, the DNA contents increased to maximum, i. e., about one half the DNA contents of the vegetative macronucleus. Polytene chromosomes were then cut by fibrillar membrane of the nature of intermediate filaments into fragments and the DNA contents of the anlage dropped to minimum, i. e., about one tenth of the maximum amount, concurrently.

关 键 词：伍氏游仆虫 大核原基 多线染色体 

分 类 号：Q959.117[生物学—动物学]