Differences in abundance of individual RNAs in normal and animalized sea urchin embryos

Shepherd, George W.; Rondinelli, Edson; Nemer, Martin

doi:10.1016/0012-1606(83)90189-6

Cited by 17 publications

(8 citation statements)

References 25 publications

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“…In both L. pictus (B2 probe; Alexandraki and Ruderman 1983)and, as illustrated in Figure 3, in S. purpuratus ("blast j l" probe; Shepherd et al 1983), the distribution of f~-tubulin mRNA is very similar to that of Spec3 throughout embryogenesis. In particular, grain densities are lowest at the vegetal pole of the blastula and in the gastrula archenteron, intermediate in aboral ectoderm and its precursors, and highest at the animal pole of blastula and gastrula, especially in the presumptive ciliated band (20 hr: cf.…”

Section: Spatial Distribution Of the Spec3 Transcript During Embryogementioning

confidence: 77%

Spec3: embryonic expression of a sea urchin gene whose product is involved in ectodermal ciliogenesis.

Eldon

Angerer

et al. 1987

Genes Dev.

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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 13-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 hydrophi!ic regions of six to eight residues. The presence of these two distinct hydrophobic stretches suggests that the Spec3 protein contains two ~-helical domains that either span the lipid bilayer or are associated with some other hydrophobic environment.

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Section: Spatial Distribution Of the Spec3 Transcript During Embryogementioning

confidence: 77%

Spec3: embryonic expression of a sea urchin gene whose product is involved in ectodermal ciliogenesis.

Eldon

Angerer

et al. 1987

Genes Dev.

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“…Nemer et al (28) showed that MT RNA, detected on gel blots by hybridization with the pMTa cDNA clone (originally designated gll) (30,37), is regulated in its endogenous expression during sea urchin embryogenesis and is inducible by zinc ions. It could not be determined, however, whether the endogenously and inducibly expressed MT mRNA represented one transcript or distinctly different transcripts.…”

Section: Resultsmentioning

confidence: 99%

“…la, lane 2). The pMTa clone used for this detection was isolated from a cDNA library of control blastula RNA (37) and, hence, seemed likely to correspond to the smaller MT mRNA. To characterize the zinc-induced, higher molecular weight MT mRNA, we constructed a cDNA library from the RNA of zinc-induced gastrulae and screened this library with nick-translated pMTa.…”

Section: Resultsmentioning

confidence: 99%

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Metallothionein genes MTa and MTb expressed under distinct quantitative and tissue-specific regulation in sea urchin embryos.

Wilkinson¹,

Nemer²

1987

Mol. Cell. Biol.

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Sea urchin embryo metallothionein (MT) mRNAs MTa and MTb have distinct cDNA sequences and are transcripts of different genes of a multigene family. These MT mRNAs differ in size and in their 3'-untranslated sequences. They encode proteins that are unusual among MT isotypes in that the relative positions of their cysteine residues are partially out of register, suggesting potential differences in function. In pluteus larvae MTa mRNA is expressed abundantly and exclusively in the ectoderm, while MTb mRNA, which is restricted to the endomesoderm at a low endogenous level, can be induced to a high level by heavy metal ions (M2+). MT mRNA is present in the maternal reservoir of the egg and is predominantly (>95%) MTa mRNA. Endogenous expression in the embryo, which is at a much higher level than in the egg, requires M2+ for gene transcription, is developmentally regulated, and is >90% MTa mRNA. When induced by added M2+, however, MTa and MTb mRNAs accumulate to almost equal levels. The differences in the ratios of MTa/MTb expressed endogenously and inductively are not attributable to differences in the stabilities of these MT mRNAs, which were observed under conditions of M2+ depletion, or in their inducibilities, which were observed at moderate to high M2+ levels. We found, instead, that the MTa gene responds to M2' at a lower threshold level than MTb, so that at very low M2+ concentrations the ratio of induced MTa/MTb mRNA is high and equivalent to the endogenous ratio. Thus, endogenous expression of the MTa gene is selectively enhanced in the ectoderm by determinants that are responsive at low M2+ threshold concentrations.Metallothioneins (MTs) are small, cysteine-rich proteins that are induced by heavy metal ions and encoded by one to several genes in the many organisms known to contain them. These proteins bind heavy metals, and it is believed that they are involved in various aspects of heavy metal metabolism, including the detoxification, storage, and intracellular transfer of these ions. The pattern of regulation of multiple MT genes is apparently diverse among higher organisms. In the mouse, for example, the MTI and MTII genes are coordinately induced by heavy metal ions, by glucocorticoids (36), and during embryonic development (1). On the other hand, the human MTIa, MTIIa, and MTIf genes are differentially regulated by various inducing agents (33) and, furthermore, display cell-type-specific expression (34,41). This diversity is consistent with the human MT genes having distinct physiological functions (33).Recent observations on the regulated expression of MT mRNA in the sea urchin embryo offer potential insights into the physiological, and especially the developmental, function of these proteins and possibly also into MT gene diversity in a system that is highly amenable to experimentation (28). Nemer et al. (28) found that in the sea urchin endogenous MT mRNA accumulation is temporally regulated during embryogenesis and is largely restricted to ectodermal tissue in the pluteus larva. Moreover, although...

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“…was obtained from the pSpB cDNA library in pBR322, representing S. purpuratus blastula polysomal RNA (Shepherd et al 1983). This 1.3-kb eDNA, previously designated Blast J1 (Nemer 1986), was subcloned into the PstI site of pUC19 by standard procedures {Maniatis et al 1982) using competent JM83 cells (Morrison 1979).…”

Section: Bacteria and Plasmidsmentioning

confidence: 99%

Developmental and tissue-specific regulation of beta-tubulin gene expression in the embryo of the sea urchin Strongylocentrotus purpuratus.

Harlow¹,

Nemer²

1987

Genes Dev.

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Differences in abundance of individual RNAs in normal and animalized sea urchin embryos

Cited by 17 publications

References 25 publications

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.

Metallothionein genes MTa and MTb expressed under distinct quantitative and tissue-specific regulation in sea urchin embryos.

Developmental and tissue-specific regulation of beta-tubulin gene expression in the embryo of the sea urchin Strongylocentrotus purpuratus.

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