牙鲆变态过程中的细胞凋亡

利用整体的原位TUNEL方法检测了牙鲆(Paralichthysolivaceus)变态过程中身体各器官细胞凋亡的分布及变化情况。结果如下:(1)与眼睛移动相关的脑颅骨骼的细胞凋亡右侧眼睛移动开始之后,在额骨、中筛软骨和犁骨软骨中出现细胞凋亡,并保持到眼睛移动结束;(2)中枢神经和感觉器官的细胞凋亡在眼睛移动开始之前,脊髓和脊髓鞘出现细胞凋亡,在眼睛移动开始之后,脊髓和脊髓鞘细胞凋亡停止,而在脑、眼睛和内耳出现细胞凋亡,并一直持续到眼睛移动结束;(3)与游泳、捕食和消化等功能相关的器官的细胞凋亡在眼睛移动开始后,冠状幼鳍的基部出现凋亡;在变态中后期,尾鳍基部出现细胞凋亡;下颌骨、鳃弓以及肝脏在眼睛移动开始之后,出现细胞凋亡,也一直持续到眼睛移动结束。细胞凋亡通过有序地去除多余的细胞来参与器官形态建立和重组,本研究的结果表明,在牙鲆器官功能变化过程中,细胞凋亡在与其相适应的的器官形态重塑中起着重要作用动物学报52(2):355-361,2006]。

Apoptosis in the metamorphosis of Japanese flounder Paralichthys olivaceus

Flatfish such as the Japanese flounder Paralichthys olivaceus are characterized by major morphological, functional, and behavioral changes during growth because of a dramatic metamorphosis from larva to juvenile. This metamorphosis involves transformation from a bilaterally symmetrical body to a laterally flattened asymmetrical one, with migration of the right eye to the left side of the body. These morphological transformations are associated with the functional development of various structures related to the evolution of larval behaviors. Apoptosis acts as a specific surveillance mechanism to remove excess cells during morphogenesis. Here we used the whole mount in situ terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick-end labeling (TUNEL) to describe the temporal and spatial distribution of apoptotic cells during metamorphosis of Japanese flounder from 13 to 43 days post hatching (dph). The results showed the cell apoptosis could play an important role in the organ-rebuilding process involving transformation and functional changes. In the neurocranium, apoptosis signals were detected in frontal bone,ethmoid cartilage and trabecular cartilage with relation to the eye movement during metamorphosis stage. Before eye movement, the apoptosis signal only appeared in spinal cord and spinal cord sheath, however, when the cell apoptosis began in the brain, eye, and inner ear in the metamorphosis process, there were no cell apoptosis in spinal cord and spinal cord sheath. Accompanying with the change of swimming type, cell began to apoptosis in the base of larval dorsal fin in initial metamorphosis stage, then, cell apoptosis were detected in base of caudal fin in the later metamorphosis stage. We also detected the signal of cell apoptosis in the jaw bone, pharyngeal bone, and liver.