Variability of the immunoglobulin light chain in the Siberian sturgeon, Acipenser baeri

All sturgeon VL segments isolated in this study belong to a single family, VLI, which can be divided into two subfamilies. Of the 79 cDNA clones isola ted, 76 belong to the larger subfamily, VLIa, and only 3 clones constitute the smaller subfamily, VLIb. To evaluate variability, the Shannon entropy w as estimated for each individual amino acid position, and to facilitate com parisons of variability between species the mean entropy of the CDR regions was calculated. In such a comparison, the sturgeon was found to have CDR1 and CDR3 variability approaching those found in mouse and clawed frog, but showed very low variability for CDR2. Amino acid position 50 does however d isplay variability in the range of mouse and clawed frog. It is further con firmed that the sturgeon has numerous J segments, bur that the junctional d iversity does not contribute greatly to the diversity of the light chain. C omparisons of cDNA clones and a genomic VL segment indicate that the VL und ergoes changes, particularly in the CDR regions, in a manner that can be ex plained by somatic hypermutation and/or gene conversion. (C) 1999 Elsevier Science Ltd. All rights reserved.