The mobilization of Tc1, a transposable element in the genome of the roundworm Caenorhabditis elegans, has been investigated. Genomic blot hybridization has shown that Tc1 exists in very different numbers in the genomes of two closely related strains of C. elegans: there are approximately 30 copies of Tc1 in the Bristol strain, whereas in the Bergerac strain there are 200-300. Most of these Tc1 elements are structurally highly conserved although there exists a second form which contains a HindIII restriction site (Tc1 (Hin) form) and comprises approximately 10% of the population. Excision of Tc1 from its chromosomal location in the Bergerac strain is indicated by the presence, on genomic blots, of a minor band corresponding to the size of the uninserted restriction fragment. Here we describe the recovery of extrachromosomal linear and closed circular copies of Tc1 from the Bergerac strain, presumably a result of Tc1 excision.

Animals↗

PubMedDate not supplied

A hemoglobin A1C immunoassay method not affected by carbamylated hemoglobin.

Hemoglobin A1C (HbA1C) methods based on charge separation of Hb species are subject to interference from carbamylated Hb (carb Hb). Carb Hb adducts are formed via interaction of terminal amino groups of HbA with isocyanic acid, after the spontaneous dissociation of urea to cyanate. It is hypothesized that a new immunoassay method, using a monoclonal antibody that recognizes the N-terminus of the Hb beta-chain and its sugar moiety, should be refractory to cross-reactive interference from carb Hb. To test this hypothesis, Hb was carbamylated in vitro and co-migration of carb Hb assessed with HbA1C using an electrophoretic method. Densitometric scans - post sodium cyanate incubation and electrophoretic separation - showed a 5 to 7 fold elevation of the HbA1C peak only, while HbA1C values obtained using immunoassay were unaffected. Also assessed was carbamylation interference in vivo, and a positive proportional bias with the electrophoretic system (Y) was observed compared to the immunoassay system (X) (y = 1.2x - 0.21 percent). Others have shown that carb Hb may cause a clinically significant false elevation in patient HbA1C values, when methods based on charge separation of Hb species are used. It is our conclusion, however, that while carb Hb may play a role, the differences observed in this study are largely due to calibration.

Antibodies, Monoclonal↗