Spec3: embryonic expression of a sea urchin gene whose product is involved in ectodermal ciliogenesis.
Spec3: embryonic expression of a sea urchin gene whose product is involved in ectodermal ciliogenesis.
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Spec3：海胆基因的胚胎表达，其产物参与外胚层纤毛发生。
DOI：
10.1101/gad.1.10.1280
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发表时间：
1987
影响因子：
10.5
通讯作者：
Klein,WH
中科院分区：
文献类型：
--
作者：
Eldon,ED;Angerer,LM;Angerer,RC;Klein,WH
我们研究了紫球海胆(StrongyLoctrotus Puratus)胚胎中SPEC3基因表达的时空特征。该基因全长2.0kb，在未受精卵中表达水平较低，但在卵裂过程中迅速积累，在孵化囊胚期增加50倍。然后，信使水平突然下降，在间充质囊胚期和原肠胚期保持不变，在棱柱期和原肠胚期再次增加。这种积累模式与Harlow和Nemer(1987A)最近描述的外胚层表达的β-微管蛋白mRNAs非常相似。原位杂交显示，虽然spec3信息在囊胚早期积聚在所有的卵裂球中，但后来它仅限于外胚层。在囊胚期后期，动物半球的杂交最强。在原肠胚中，信号在外胚层上是可变的，而在丛生植物中，颗粒集中在纤毛带中，尽管也存在于其他外胚层细胞中。原肠胚期胚胎纤毛的剥离和再生导致Spe3基因表达水平增加四到五倍，这意味着spec3基因产物与纤毛发生有关。SPEC3基因由单倍体基因组中的单个基因编码，序列分析表明该基因含有3个外显子，编码21.6kD疏水蛋白的开放阅读框。阅读框架显示，该蛋白质的羧基末端含有两个长的疏水延伸部分，分别为31和37个残基，由6到8个残基的短亲水区域隔开。这两个截然不同的疏水延伸的存在表明，spec3蛋白含有两个α-螺旋结构域，它们要么跨越脂质双层，要么与其他一些疏水环境相关。
We have characterized the temporal and spatial expression of Spec3 mRNA in embryos of the sea urchin, Strongylocentrotus purpuratus. This mRNA, 2.0 kb in length, is present at low levels in unfertilized eggs but accumulates rapidly during cleavage, increasing 50-fold by hatching blastula stage. Message levels then decline abruptly, remain constant during mesenchyme blastula and gastrula stages, and increase again during prism and pluteus stages. This accumulation pattern is quite similar to that of the ectodermally expressed beta-tubulin mRNAs described recently by Harlow and Nemer (1987a). In situ hybridization shows that although Spec3 message accumulates in all blastomeres at early blastula stages, it later becomes restricted to ectoderm. By late blastula stage, hybridization is strongest in the animal hemisphere. At gastrula, signals are variable over ectoderm, and by pluteus, grains are concentrated in the ciliary band, though present in other ectodermal cells as well. Deciliation and regeneration of cilia in gastrula-stage embryos results in a four- to fivefold increase in Spec3 mRNA levels, implying that the Spec3 gene product is associated with ciliogenesis. Spec3 mRNA is encoded by a single gene in the haploid genome, and characterization of the gene shows that it contains three exons that encode an open reading frame for a hydrophobic protein of 21.6 kD. The reading frame reveals that the carboxy-terminal part of the protein contains two long hydrophobic stretches, 31 and 37 residues long, separated by short hydrophilic regions of six to eight residues. The presence of these two distinct hydrophobic stretches suggests that the Spec3 protein contains two alpha-helical domains that either span the lipid bilayer or are associated with some other hydrophobic environment.