Chitin is produced by a variety of organisms using enzymes called chitin synthases and was recently discovered in certain vertebrates. In our ongoing investigations into the presence of vertebrate chitin, we unexpectedly found it within the electrosensory organs, known as Ampullae of Lorenzini, of diverse cartilaginous fishes. We used histochemical reagents, chemical analyses, and enzymatic digestions to confirm our findings. Further, in situ hybridization with a sequence from the little skate (Leucoraja erinacea) revealed that chitin synthase expression is localized to cells inside the organs. These findings indicate that cartilaginous fishes endogenously synthesize chitin and beg further investigation into the function of chitin in the electrosensory system.

Chitin is synthesized by a variety of organisms using enzymes called chitin synthases and was recently discovered in a number of aquatic vertebrates. In our ongoing investigations into the presence of vertebrate chitin, we unexpectedly found evidence of the polysaccharide within the electrosensory organs, known as Ampullae of Lorenzini, of diverse chondrichthyan fishes. Experiments with histochemical reagents, chemical analyses, and enzymatic digestions suggested that chitin is a component of the hydrogel filling the structures. Further, in situ hybridization with a sequence from the little skate (Leucoraja

The variable lymphocyte receptors (VLRs) consist of leucine rich repeats (LRRs) and comprise the humoral antibodies produced by lampreys and hagfishes. The diversity of the molecules is generated by stepwise genomic rearrangements of LRR cassettes dispersed throughout the VLRB locus. Previously, target-specific monovalent VLRB antibodies were isolated from sea lamprey larvae after immunization with model antigens. Further, the cloned VLR cDNAs from activated lamprey leukocytes were transfected into human cell lines or yeast to select best binders. Here, we expand on the overall utility of the VLRB technology by introducing it into a filamentous phage display system. We first tested the efficacy of isolating phage into which known VLRB molecules were cloned after a series of dilutions. These experiments showed that targeted VLRB clones could easily be recovered even after extensive dilutions (1 to 10 9 ). We further utilized the system to isolate target-specific "lampribodies" from phage display libraries from immunized animals and observed an amplification of binders with relative high affinities by competitive binding. The lampribodies can be individually purified and ostensibly utilized for applications for which conventional monoclonal antibodies are employed.

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