Chan Siu-Ming, Gu Pei-Li, Chu Ka-Hou, Tobe Stephen S
Department of Zoology, The University of Hong Kong, Pokfulam Road, Hong Kong, China.
Gen Comp Endocrinol. 2003 Dec;134(3):214-9. doi: 10.1016/s0016-6480(03)00263-6.
The crustacean eyestalk CHH/MIH/GIH gene family represents a unique group of neuropeptide originally identified in crustaceans. These neuropeptides shared a high degree of amino acid identity, and the conservation of cysteine residues at the same relative positions. Based on their biological, biochemical, and molecular properties, they can be divided into the CHH and MIH subtypes with two major members in each subtype. In the shrimp, the CHH-subtypes can be divided into two forms (CHH-A and CHH-B). The CHH-A gene also comprises several isoforms which shared a high overall sequence identity. Although the MIH subtypes are postulated to have evolved from the CHH subtypes, the number of major MIH subtypes in each species has yet to be confirmed. While most of the genes consist of the basic plan of three exons and two introns, other alternative spliced variants have recently been described. Moreover, these alternative forms are usually expressed in non-eyestalk tissues. These findings suggest that these neuropeptides may have a broader spectrum of functions in crustaceans. The results from phylogenetic analysis suggest that the evolution of this group of neuropeptides occurs in a manner similar is to the gene duplication and mutation events hypothesized for the origin of the prolactin and growth hormone gene family of the vertebrate pituitary system.
甲壳类动物眼柄CHH/MIH/GIH基因家族代表了一类最初在甲壳类动物中发现的独特神经肽。这些神经肽具有高度的氨基酸同一性，并且在相同相对位置的半胱氨酸残基保守。基于它们的生物学、生化和分子特性，它们可分为CHH和MIH亚型，每个亚型有两个主要成员。在虾中，CHH亚型可分为两种形式（CHH-A和CHH-B）。CHH-A基因也包含几个具有高度总体序列同一性的同工型。虽然推测MIH亚型是从CHH亚型进化而来，但每个物种中主要MIH亚型的数量尚未得到证实。虽然大多数基因由三个外显子和两个内含子的基本结构组成，但最近也描述了其他可变剪接变体。此外，这些可变形式通常在非眼柄组织中表达。这些发现表明这些神经肽在甲壳类动物中可能具有更广泛的功能谱。系统发育分析结果表明，这组神经肽的进化方式类似于为脊椎动物垂体系统催乳素和生长激素基因家族起源所假设的基因复制和突变事件。
