Fucose/metabolism; Fucosyltransferases/metabolism; Immunoglobulin mu-Chains/metabolism; Precursor Cells, B-Lymphoid/metabolism; Receptors, Antigen, B-Cell/metabolism; Signal Transduction/physiology; Animals; Fucose/genetics; Fucose/immunology; Fucosyltransferases/genetics; Fucosyltransferases/immunology; Glycosylation; Immunoglobulin A/genetics; Immunoglobulin A/immunology; Immunoglobulin A/metabolism; Immunoglobulin G/genetics; Immunoglobulin G/immunology; Immunoglobulin G/metabolism; Immunoglobulin M/genetics; Immunoglobulin M/immunology; Immunoglobulin M/metabolism; Immunoglobulin lambda-Chains/genetics; Immunoglobulin lambda-Chains/immunology; Immunoglobulin lambda-Chains/metabolism; Immunoglobulin mu-Chains/genetics; Immunoglobulin mu-Chains/immunology; Mice; Mice, Knockout; Precursor Cells, B-Lymphoid/immunology; Receptors, Antigen, B-Cell/genetics; Receptors, Antigen, B-Cell/immunology