Cloning and spatiotemporal expression of Xenopus laevis Apolipoprotein CI

Apolipoprotein CI (ApoCI) belongs to the Apolipoprotein superfamily, members of which are involved in lipid transport, uptake and homeostasis. Excessive ApoCI has been implicated in atherosclerosis and Alzheimer’s disease in humans. In this study we report the isolation of Xenopus laevis apoCI and describe the expression pattern of this gene during early development, using reverse transcription polymerase chain reaction and whole mount in situ hybridization. Xenopus apoCI is enriched in the dorsal ectoderm during gastrulation, and is subsequently expressed in sensory placodes, neural tube and cranial neural crest. These data suggest as yet uncharacterized roles for ApoCI during early vertebrate embryogenesis

Temporal expression of a<i>poCI</i> mRNA.

<p>RT-PCR of RNA isolated from whole embryos between stage 4 and stage 32. <i>Chordin</i> serves as a staging control and <i>Ornithine decarboxylase</i> (ODC) as a control for input RNA levels.</p

Sequence analysis of <i>Xenopus apoCI</i>.

<p>(A) Nucleotide sequence and deduced amino acid sequence of <i>Xenopus apoCI</i> (GenBank accession number: GU562893). Predicted signal sequence of <i>Xenopus</i> ApoCI spans residues 1–20. (B) Phylogenetic tree depicting evolutionary relationship of human Apolipoproteins AI, AII, AIV, B, CI, CII, CIII and E to <i>Xenopus Apolipoprotein CI</i>. The tree was constructed using the UPGMA distance matrix method from CLC Bio Workbench. Numbers at nodes indicate branch length.</p

Cloning and spatiotemporal expression of <i>Xenopus laevis Apolipoprotein CI</i>

<div><p>Apolipoprotein CI (ApoCI) belongs to the Apolipoprotein superfamily, members of which are involved in lipid transport, uptake and homeostasis. Excessive ApoCI has been implicated in atherosclerosis and Alzheimer’s disease in humans. In this study we report the isolation of <i>Xenopus laevis apoCI</i> and describe the expression pattern of this gene during early development, using reverse transcription polymerase chain reaction and whole mount <i>in situ</i> hybridization. <i>Xenopus apoCI</i> is enriched in the dorsal ectoderm during gastrulation, and is subsequently expressed in sensory placodes, neural tube and cranial neural crest. These data suggest as yet uncharacterized roles for ApoCI during early vertebrate embryogenesis.</p></div

Spatial expression of <i>apoCI</i> mRNA.

<p>Vegetal (A, B) and lateral (A’, B’) views of stage 10 (A, A’) and stage 11 (B, B’) embryos, respectively; <u><i>a</i></u><i>poCI</i> transcript is localized to the dorsal ectoderm. Dotted lines in A, A’ mark the dorsal blastopore lip and dotted lines in B, B’ indicate the blastopore. Dorsal is to left in A, A’, B; dorsal is at 10 o’clock in B’. (C, D) Anterior views of <i>apoCI</i> expression in stage 13 and stage 15 embryos, respectively (dorsal to the top). Dotted line in D marks the pan-placodal primordium. (C’, D’) Dorsal views of embryos in C and D, respectively; anterior is down. (E) Anterior view of a stage 16 embryo; the anterior crescent of <i>apoCI</i> expression has expanded laterally. (F-L) Dorsoanterior views of stage 15 embryos; anterior is down and dorsal is to the top. (F) <i>apoCI</i> expression. (G) <i>slug</i> expression. (H) <i>apoCI</i> (purple) and <i>slug</i> (light blue) coexpression; arrows indicate region of overlap (cranial neural crest). (I) <i>pax6</i> expression. (J) <i>apoCI</i> (purple) and <i>pax6</i> (light blue) coexpression. (K) <i>otxA</i> expression. (L) <i>apoCI</i> (purple) and <i>otxA</i> (light blue) coexpression. (M, N) Anterior (M, dorsal is to the top) and dorsal (N, anterior is down) views showing <i>apoCI</i> expression in a stage 21 embryo. (O) Transverse section revealing expression of <i>apoCI</i> in the dorsal neural tube at stage 22; star indicates the neural tube. (P, Q) Lateral views of <i>apoCI</i> expression in stage 27 and stage 33 embryos, respectively; anterior is to the left. Arrow in Q marks liver primordium. No signal was detected with an <i>apoCI</i> sense strand probe (data not shown).</p