Embryogenesis and expression profiles of charon and nodal-pathway genes in sinistral (Paralichthys otivaceus) and dextral (Verasper variegatus) flounders
Embryogenesis and expression profiles of charon and nodal-pathway genes in sinistral (Paralichthys otivaceus) and dextral (Verasper variegatus) flounders
复制标题
DOI：
10.2108/zsj.24.137
复制
发表时间：
2007-02-01
影响因子：
0.9
通讯作者：
Suzuki, Tohru
中科院分区：
文献类型：
--
作者：
Hashimoto, Hisashi;Aritaki, Masato;Suzuki, Tohru
虽然众所周知，比目鱼在变态时通过一只眼睛的移动形成外部不对称，但形成这种不对称的控制系统尚不清楚。为了帮助阐明这一机制，我们在这里描述了牙鲆(Paralichthys Olivaceus)的胚胎发生和节路基因的表达谱。我们还比较研究了这些基因在左翼(P.olivaceus)和右翼(Verasper Varegatus)中表达的侧向性。在橄榄科动物中，Kupffer‘s囊泡在2体节时期形成，之后Spaw的左侧表达从8体节时期开始。左侧表达在15体节至高体节阶段的肠野、21体节至高体节阶段的心区和27体节至高体节阶段的背侧间脑。作为对左侧Pitx2表达的响应，心脏、肠道和间脑在咽部(心脏)和长心皮(肠道和间脑)阶段开始不对称器官发生，而眼睛在这些阶段没有不对称的迹象。在左旋和右旋牙鲨中，结节通路基因在背侧间脑和左侧板状中胚层的左侧表达。考虑到这些数据，以及我们之前的发现，在P olivaceus的突变体Reverted中，眼睛的偏侧性在一定程度上发生了逆转，其中胚胎bitx2的表达是随机的，我们认为尽管Nodal通路似乎具有固定眼睛偏侧性的功能，但这些基因的胚胎表达并不能作为眼睛偏侧性的直接位置线索。
Although it is well known that flounder form external asymmetry by migration of one eye at metamorphosis, the control system that forms this asymmetry is unknown. To help elucidate this mechanism, we here describe the embryogenesis and expression profiles of the Nodal-pathway genes in the Japanese flounder, Paralichthys olivaceus. We also perform a comparative study of the laterality of the expression of these genes in sinistral (P. olivaceus) and dextral (Verasper variegatus) flounders. In P olivaceus, Kupffer's vesicle forms at the 2-somite stage, after which left-sided expression of spaw starts at the 8-somite stage. Left-sided expression of pitx2 occurs in the gut field at the 15-somite to high-pec stages, in the heart field at the 21-somite stage, and in the dorsal diencephalon at the 27-somite to high-pec stages. In response to left-sided pitx2 expression, the heart, gut, and diencephalon begin asymmetric organogenesis at the pharyngula (heart) and the long-pec (gut and diencephalon) stages, whereas the eyes do not show signs of asymmetry at these stages. In both sinistral and dextral flounders, the Nodal-pathway genes are expressed at the left side of the dorsal diencephalon and left lateral-plate mesoderm. Considering these data together with our previous finding that reversal of eye laterality occurs to some extent in the P olivaceus mutant reversed, in which embryonic pitx2 expression is randomized, we propose that although the Nodal pathway seems to function to fix eye laterality, embryonic expression of these genes does not act as a direct positional cue for eye laterality.