Details

Autor(en) / Beteiligte

• Zucchetti, Ivana

Titel

Expression of immunoglobulin superfamily and a C -type lectin genes in the tunicate Ciona intestinalis

Ort / Verlag

ProQuest Dissertations & Theses

Erscheinungsjahr

2005

Link zum Volltext

Quelle

ProQuest Dissertations & Theses A&I

Beschreibungen/Notizen

• In Metazoa, the maintenance of individuality and the defence against pathogens is devolved to the many molecular mechanisms of the immune system. In gnathostome vertebrates, where a unique adaptive system has developed, the essential elements of immunity are a set of somatically generated receptors belonging to the immunoglobulin superfamily and a set of germ-line encoded lectin receptors. The Urochordate Ciona intestinalis, as the other invertebrates, does not have a gnathostome type adaptive immune system, but, for its phylogenetic position, represents an excellent model for a comparative study of the elements and of the possible evolutionary pathways that led to the assembly of the adaptive system. The sequencing of the Ciona genome has revealed the presence of genes that may be considered putative ancestral receptors involved in self-nonself recognition of the adaptive system. Among these I have selected for study three genes: one lectin and two immunoglobulin superfamily members. The lectin gene, Ci-KLL, encodes a C-type lectin with sequence homology with vertebrates CD94, a marker of Natural Killer cells involved in recognition of major histocompatibility complex (MHC) class I molecules. The two immunoglobulin superfamily genes, Ci-Nec2 and Ci-CTX/JAM possess a domain related to the immunoglobulin variable domain of the lymphocyte receptors and have homology with markers of gnathostome lymphocytes. I have studied the expression of these genes using PCR, in situ hybridization and immunochemistry during development and in the adult tissues of Ciona. All three genes are expressed in some cells of the hematopoietic lineage in different body compartments, and in relation to treatment with bacterial lipopolysaccharide, thus suggesting an involvement in the immune system. They are also detected in other systems, where recognition might also be essential: in the gametes and in the nervous system during development. Ci-KLL and Ci-Nec2 are expressed during spermatogenesis and oogenesis, respectively. Ci-KLL and Ci-CTX/JAM are expressed in the nervous system of the larval stage. These findings underline the possibility of gene co-option between different systems during evolution and of evolutionary relationships between the nervous and the immune systems.