Analysis of the Elephant Immunoglobulin Genes Figure 11. Phylogenetic analysis of the 12 elephant Vl genes. A phylogenetic tree of the nucleotide sequences of the 12 elephant Vl segments was constructed. The 12 elephant Vl gene segments belong to six families, which are clustered with the human Vl 1, 3, 4, 7, 9, and 10 families, respectively. The credibility value for each node is shown. doi:10.1371/journal.pone.0016889.g011 repertoire is k (40 functional Vk genes vs. 30 functional Vl genes). The germline Vk genes of mice are dominant by as much as 95% or more [84]. It has been proposed that the preferential use of light chain isotypes at the protein level may be correlated with the overall number of V gene segments [84]. It is thus possible that the k chain predominates over the l chain at the protein level in elephants. Interestingly, a great number of pseudogenes exist in the elephant VH (61/112), Vk (100/153), and Vl (13/15) loci. In some species, the base-pair changes could be inferred using an existing pseudogene or germline gene as a template, and therefore pseudogenes in the V loci constitute a potential donor pool for gene conversion to generate immunoglobulin diversity [85–88]. A great number of V pseudogenes may contribute to the immuno- globulin diversity in elephants. The study of structure and organization of the immunoglobulin gene loci is vital to the understanding of the nature of antibody molecules. This study provides information for comparative studies of mammalian Ig genes, as well as data for further studies of the elephant immunoglobulin genes. PLoS ONE | www.plosone.org 11 February 2011 | Volume 6 | Issue 2 | e16889