A highly immunogenic region of a human polymorphic epithelial mucin expressed by carcinomas is made up of tandem repeats.

Publisher Summary This chapter presents considerable evidence for morphogenetic functions of neurotransmitters during embryonic development, a role that may derive from their appearance early in evolution, still evidenced today by their presence in primitive organisms. Use of the term “morphogen” in the context of neurotransmitters acting as regulators of morphogenetic processes gives it a more general meaning. Turing has originally defined it in a rather broad sense, even including hormones as possible morphogens. Neurotransmitter substances, including the catecholamines, serotonin acetylcholine and γ-aminobutyric acid (GABA), are found in a variety of primitive organisms and early invertebrate embryos in which no nervous system is present. In such cases, these substances appear to act as both intra- and intercellular signals involved in the control of cell proliferation, ciliary activity, motility, cell shape changes and morphogenetic cell movements. In the adult nervous system, neurotransmitters are discrete intercellular signalling devices that mediate communication between cells in complex neural circuitries. However, they may have evolved to this specialized role from more general humoral functions in primitive organisms where they were used as both intra- and intercellular signalling devices.

Neurotransmitters as morphogens.

https://www.cell.com/cell/pdf/S0092-8674(00)80276-7.pdf

SH2 Signaling in a Lower Eukaryote: A STAT Protein That Regulates Stalk Cell Differentiation in Dictyostelium

Glycogen synthase kinase 3 regulates cell fate in Dictyostelium.

We are only starting to understand the molecular mechanisms that underlie cell and tissue movements during morphogenesis in metazoans. Dictyostelium discoideum provides a valuable model system for understanding these events — as it has for chemotaxis — despite the many differences that exist between this social amoeba and more complex organisms. Genetic and genomic studies, combined with real-time imaging, have identified key pathways that regulate morphogenesis in D. discoideum, and which are likely to have similar roles in metazoans.

Insights into morphogenesis from a simple developmental system.

https://www.cell.com/cell/pdf/0092-8674(87)90559-9.pdf

M. Berks

Papers

Direct induction of dictyostelium prestalk gene expression by DIF provides evidence that DIF is a morphogen