The joining (J) chain is present in invertebrates that do not express immunoglobulins.

Joining (J) chain is a component of polymeric, but not monomeric, immunoglobulin (Ig) molecules and may play a role in their polymerization and transport across epithelial cells. To date, study of the J chain has been confined to vertebrates that produce Ig and in which the J chain displays a considerable degree of structural homology. The role of the J chain in Ig polymerization has been questioned and, since the J chain can be expressed in lymphoid cells that do not produce Ig, it is possible that the J chain may have other functions. To explore this possibility, we have surveyed J-chain gene, mRNA, and protein expression by using reverse transcriptase-coupled PCR, Northern blot analysis, and immunoblot analysis in invertebrate species that do not produce Ig. We report that the J-chain gene is expressed in invertebrates (Mollusca, Annelida, Arthropoda, Echinodermata, and Holothuroidea), as well as in representative vertebrates (Mammalia, Teleostei, Amphibia). Furthermore, J-chain cDNA from the earthworm has a high degree of homology (68-76%) to human, mouse, and bovine J chains. Immunohistochemical studies reveal that the J chain is localized in the mucous cells of body surfaces, intestinal epithelial cells, and macrophage-like cells of the earthworm and slug. This study suggests that the J chain is a primitive polypeptide that arose before the evolution of Ig molecules and remains highly conserved in extent invertebrates and vertebrates.

Variation in Bornean frogs of the Amolops jerboa species group, with description of two new species / Robert F. Inger, Paul A. Gritis.

n.s. no.19(1983)

The Cambridge natural history,

Vols. 1, 2, 5-7, 9 reprinted 1922; v. 3, 1927; and vols. 4, 8, 10, 1923.

Catalogue of the Batrachia salientia in the collection of the British Museum /

Índice.

Caroli a Linné ... Systema naturae per regna tria naturae Secundum Classes, Ordines, Genera, Species, cum Characteribus, Differentiis, Synonymis, Locis ... /

Contiene: T. 1: Pars I: Mammalia, Aves. Pars II: Aves. Pars III: Amphibia reptilia, Serpentes, Pisces. Pars IV: Insecta Coleoptera, Hemiptera. Pars V: Insecta lepidoptera. Pars VI: Vermes. Pars VII: Index ; T.2: Regnum vegetabile ; T.3: Regnum lapideum.