Activation of sea urchin actin genes during embryogenesis

Early expression of a collagenase-like hatching enzyme gene in the sea urchin embryo.

“…These transcripts code for various types of protein including proteins of the troponin C family (Bruskin et al, 1981), extracellular matrix proteins (Angerer et al, 1988;Nocente-McGrath et al, 1989), cytoskeletal actins (Lee et al, 1986), homeodomain containing proteins (Dolecki et al, 1986), cell surface proteins (Yang et al, 1989a), proteins involved in the building of the skeleton or specific to the micromere lineage (Grant et al, 1985;Benson et al, 1987;Harkey et al, 1988) and EGF-related proteins (Yang et al, 1989b). However, nearly all the transcripts so far characterized are specific to the late stages such as the mesenchyme blastula, gastrula or pluteus.…”

An in vivo titration of regulatory factors required for expression of a fusion gene in transgenic sea urchin embryos.

“…The gene is transcriptionally activated 10-12 hr postfertilization (3)(4)(5) and is expressed throughout embryonic development, exclusively in the six cell lineages from which derive the aboral ectoderm of the completed pluteus (6)(7)(8). A fusion construct consisting of the chloramphenicol acetyltransferase (CAT; acetyl-CoA:chloramphenicol 03-acetyltransferase, EC 2.3.1.28) reporter gene under the control of upstream CyIIIa sequences (CyIIIa-CAT fusion gene) has been microinjected into unfertilized eggs (9).…”

Rare maternal mRNAs code for regulatory proteins that control lineage-specific gene expression in the sea urchin embryo.

“…The number of P3A1 and P3A2 mRNA molecules transcribed in S. purpuratus eggs and early embryos was determined using single-stranded antisense RNA probe excess titration, as described by Lee et al. (14). Reactions were carried out in tracer excess of 10-fold or greater, at a solution hybridization criterion of 50°C, 0.4 M NaCl, and 50% formamide.…”

“…Reactions were carried out in tracer excess of 10-fold or greater, at a solution hybridization criterion of 50°C, 0.4 M NaCl, and 50% formamide. The amount of RNARNA hybrid formed was assayed by trichloroacetic acid precipitation after digestion with RNase A and RNase T1 (14). P3A1 and P3A2 single-stranded antisense RNA probes were prepared from linearized plasmid DNA.…”

“…The number of transcripts per embryo was determined from least-squares slopes of the titration measurements (i.e., probe protected as a function of total RNA per reaction; ref. 14).…”