Mechanisms of eye relocation during flatfish metamorphosis, - asymmetrical morphogenesis by thyroid hormone

比目鱼变态过程中眼睛重新定位的机制，-甲状腺激素导致的不对称形态发生

• 批准号: 14540614
• 负责人: TAGAWA Masatomo
• 金额: $ 2.3万
• 依托单位: Kyoto University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2002
• 资助国家: 日本
• 起止时间: 2002 至 2004
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-14540614/
• 关键词: metamorphosis; left-right asymmetry; body color; eye relocation; flatfish; thyroid hormone; timing in early development; malformation; 甲状腺ホルモン感受性; タイミング; pseudomesial bar; ヒラメ; カレイ類; 部域差; ホシガレイ; retrorbital vesicle

The external asymmetry of flatfish is most significant in the animal kingdom. One eye of the symmetrical larva migrates to the opposite side, and the side with both eyes (ocular side) becomes dark by the expression of the adult-type melanophores(aMLP) during metamorphosis, particularly under the control of thyroid hormones(THs).The pseudomesial bar(Pb), a unique bone that is present in flatfish only on the side without eyes (blind side), simultaneously developed with the progress of eye migration during metamorphosis. Since Pb required TH at a specific time, the involvement of TH was indicated in the formation of the blind side. From in vivo and in vitro experiments, it was suggested that TH also plays a role in the coloration of the blind side by suppressing the spontaneous expression of aMLP.To answer the question why TH can exert its effect only on the future blind side, the larvae of spotted halibut were artificially metamorphosed by TH treatment at various timings. The occurrence of "ambicoloration" (ocular-side characteristic on both the sides) was increased by metamorphosis under the action of TH that was either too early or too late. On the other hand, "pseudoalbino" (blind-side characteristic on both sides) was observed under the action of TH at a specific time. Based on the results, TH responsiveness to induce blind-side characteristic was estimated. The responsive period was longer for the left side (blind side in the normal juveniles) than for the right side, and this difference was believed to be the central mechanism for the metamorphic asymmetry.

比目鱼的外部不对称性在动物界是最显著的。在变态过程中，特别是在甲状腺激素(TH)的控制下，成体类型黑素载体(AMLP)的表达使对称幼虫的一只眼向对侧迁移，双眼所在的一侧(眼侧)变暗。伪眉骨(Posomesial bar，铅)是一种独特的骨骼，只存在于比目鱼的无眼一侧(盲侧)，在变态过程中随着眼睛迁移的进展而同时发育。由于铅在特定时间需要TH，因此TH参与了盲侧的形成。从体内和体外实验表明，TH还通过抑制aMLP的自发表达而在盲侧着色中发挥作用。为了回答为什么TH只能在未来的盲侧发挥作用的问题，我们在不同的时间用TH处理了斑点比目鱼的幼体。在太早或太晚的TH作用下，变态增加了双眼变色(双眼双眼特征)的发生。在TH作用下，可在一定时间内观察到假白化现象(双侧盲侧特征)。在此基础上，对诱发盲侧特征的反应性进行了估计。左侧(正常青少年的盲侧)的反应期比右侧长，这一差异被认为是变性不对称的中心机制。

项目成果

Hashimoto H, Mizuta A, Okada N, Suzuki T, Tagawa M, et al.: "Isolation and characterization of a Japanese flounder clonal line, reversed, which exhibits reversal of metamorphic left-right asymmetry"Mechanisms of Development. 111. 17-24 (2002)

Hashimoto H、Mizuta A、Okada N、Suzuki T、Takawa M 等人：“日本比目鱼克隆系的分离和表征，反向，表现出变质左右不对称性的逆转”发育机制。

Histological study of deformity in eye location in Japanese flounder Paralichthys olivaceus.

日本牙鲆眼部畸形的组织学研究。

• 发表时间: 2003
• 期刊: Fisheries Science 69
• 作者: OKADA;Nozomi
• 通讯作者: Nozomi

Okada N, Takagi Y, Tanaka M, Tagawa M: "Fine structure of soft and hard tissues involved in eye migration in metamorphosing Japanese flounder (Paralichthys olivaceus)"Anatomical Record A. 273A. 663-668 (2003)

Okada N、Takagi Y、Tanaka M、Takawa M：“变态日本比目鱼（Paralichthys olivaceus）眼睛迁移中涉及的软硬组织的精细结构”解剖记录 A. 273A。

Okada N, Tanaka M, Tagawa M: "Bone development during metamorphosis of the Japanese flounder (Paralichthys olivaceus) : differential responses to thyroid hormone""The Big Fish Bang". (Eds.H.I.Browman & A.B.Skiftesvik) Institute of Marine Research, Bergen,

Okada N、Tanaka M、Takawa M：“日本比目鱼（Paralichthys olivaceus）变态过程中的骨骼发育：对甲状腺激素的差异反应”“大鱼爆炸”。

Production of symmetrical flatfish by controlling the timing of thyroid hormone treatment in spotted halibut Verasper variegatus.

• DOI: 10.1016/j.ygcen.2005.01.013
• 发表时间: 2005-04
• 期刊: General and comparative endocrinology
• 影响因子: 2.7
• 作者: M. Tagawa;M. Aritaki