LpC1

Function

LpC1 gene codes for the cytosceletal type actin (Fang et al., 1996). Actin represents one of the most abundunt and best characterized structural components in eucaryotic cells, involved in a wide variety of cytoskeletal, locomotive, and tension-generating functions (Davidson, 1989).
Each haploid L. pictus genome contains a single copy of each of the actin genes LpC1, LpC2, LpC3, LpC4, and LpM. Southern blot analysis of genomic DNA clones have detected no close linkage of L.pictus actin genes in contrast to the cytosceletal actins of S. purpuratus, which are clustered into two linkage groups of related genes (Fang et al., 1996).

Protein

LpC1 protein belongs to a family of the cytoskeletal actins (Fang et al., 1996).
SWISS_PROT: P53465

Subcellular location

Cytoplasmic

Expression Pattern

LpC1 mRNA is the most abundant actin mRNA expressed during embryogenesis.
At the mesenchyme blastula stage the 2.1-kb LpC1 transcripts become detectable in several cells at the center of the vegetal plate.
During gastrulation, the LpC1 actin gene is expressed exclusively in the cells located on the tip of the elongating archenteron, the prospective secondary mesenchyme cells (SMCs). Later in gastrulation, these stained cells ingress from the tip of the archenteron to form secondary mesenchyme. Some, maybe all, of them migrate along the ectodermal wall, then penetrate and are retained along the ectodermal epithelium; these cells are presumably the pigment-forming SMCs.
Endodermal cells, especially near the blastopore, begin to accumulate the LpC1 mRNA during gastrulation. A few primary mesenchyme cells (PMCs) are heavily stained in gastrulae. Some heavily stained secondary mesenchyme cells are not embedded in the ectodermal wall, but are scattered in the blastocoel. These cells probably belong to the subpopulation of secondary mesenchyme cells, such as the blastopore masenchyme cells.
The LpC1 gene is subsequently expressed in the ectoderm cells (ECs) at very low levels in late gastrula and thereafter.
Most of the large increase in prevalence of LpC1 RNA between prism and pluteus stages is due to accumulation in the differentiated gut, especially in the stomach and intestine (Fang et al., 1996).

mRNA level

Temporal accumulation
Method: Nothern blot hybridization
Reference: Fang et al., 1996

Stage Egg Hatched blastula Mesenchyme blastula Late gastrula Prism Pluteus

Level - - + + + +

Spatial localization
Method: Whole mount in situ hybridization
Reference: Fang et al., 1996

Stage Egg Hatched blastula Mesenchyme blastula Early gastrula Late gastrula Early pluteus

Tissue - - Several cells at the center of the vegetal plate Prospective SMCs at the tip of archenteron (presumably pigment-forming cells) SMCs (presumably pigment-forming cells), endoderm cells near the blastopore, few PMCs, some SMCs not embedded in ectodermal wall, but scattered in blastocoel, ECs Gut (stomach, intestine), ECs