Anomalous side chain amidation in plasma membrane proteins of simian virus 40-transformed lymphocytes indicated by isoelectric focussing and laser Raman spectroscopy.

Plasma membranes isolated from normal hamster lymphocytes and lymphoid cells transformed by SV40¹ have been compared. Isoelectric focussing in 1% Triton $\text{X-100}\text{8M}$ urea reveals higher isoelectric points than normal for the non-glycosylated proteins in the membranes of transformed cells. This suggests greater amidation of membrane aspartates and/or glutamates. The focussing patterns also reveal a shift to lower pH for the isoelectric points of most glycosylated proteins suggesting increased silalylation. The Amide I – Amide II laser Raman spectra of the two membrane categories are consistent with greater side chain amidation in the membranes of neoplastic lymphocytes.     

A possible cause of non-disjunction of additional chromosome 21 in Down syndrome

Summary A possible cause of non-disjunction of chromosome 21 in Down Syndromes has been cytogenetically evaluated by examining the parents by Ag-staining technique. In all the cases studied so far, the contributing parents have active ribosomal cistrons on both chromosomes 21 i.e. both chromosomes are stained positively by silver staining. These results show that the active NORs might play an essential role in meiotic non-disjunction. Furthermore, the preliminary results demonstrate that the acrocentric associations of homologous and non-homologous nature involving chromosome 21 are the most frequent in the contributing parent which may further indicate the role of multiple cellular factors affecting the associations in promoting the non-disjunction in addition to active NORs. The possible mechanisms regarding the non-disjunction of chromosome 21 have been described.Presented at the 34th Annual Meeting of the American Society of Human Genetics, Norfolk, VA, USA