Peptides That Bind Specifically to an Antibody from a Chronic Lymphocytic Leukemia Clone Expressing Unmutated Immunoglobulin Variable Region Genes

Chronic lymphocytic leukemia (CLL) is a clonal disease of a subset of human B lymphocytes. Although the cause of the disease is unknown, its development and evolution appear to be promoted by signals delivered when B-cell receptors (BCRs) engage (auto)antigens. Here, using a peptide phage display library of enhanced size and diverse composition, we examined the binding specificity of a recombinant monoclonal antibody (mAb) constructed with the heavy chain and light chain variable domains of a CLL BCR that does not exhibit somatic mutations. As determined by testing the peptides identified in the selected peptide phage pool, this CLL-associated unmutated mAb bound a diverse set of sequences, some of which clustered in families based on amino acid sequence. Synthesis of these peptides and characterization of binding with the CLL-associated mAb revealed that mAb-peptide interactions were generally specific. Moreover, the mAb-peptide interactions were of lower affinities (micromolar K_D), as measured by surface plasmon resonance, than those observed with a CLL mAb containing somatic mutations (nanomolar K_D) and with immunoglobulin heavy chain variable (IGHV)-mutated antibodies selected by environmental antigens. This information may be of value in identifying and targeting B lymphocytes expressing specific BCRs in CLL patients and healthy subjects with monoclonal B lymphocytosis.     

Polyamine levels during the development of zygotic and somatic embryos of Pinus radiata

Changes in the cellular content of three polyamines (putrescine, spermidine and spermine) were compared at different stages of development in zygotic and somatic embryos of Pinus radiata D. Don . During embryo development, both the zygotic and the somatic embryos showed a steady increase in spermidine content, with either a small decrease or no significant change in putrescine. This led to a several-fold increase in spermidine/putrescine ratios during development of both types of embryos. Cell cultures of plant-forming and non-plant-forming lines derived from the same clone and growing on proliferation (maintenance) medium differed significantly in their polyamine levels. Mature, cotyledonary stage somatic embryos capable of germination and formation of plants could be distinguished by their higher spermidine/putrescine ratios from abnormal cotyledonary stage somatic embryos which were incapable of forming plants.     

Mass spectrometry of silylated flavone and flavanone glycosides

The electron impact mass spectra of 14 trimethylsilylated flavone and flavanone mono- and diglycosides are reported for the first time. All spectra show well defined molecular ion peaks and those of O-glycosides additionally give evidence of the aglycone and the sugar(s), the sugar attachment, the sugar sequence and the interglycosidic linkage (of flavone and flavanone biosides).