An abnormal but functionally active complement component C9 protein found in an Irish family with subtotal C9 deficiency

Two independently segregating C9 genetic defects have previously been reported in two siblings in an Irish family with subtotal C9 deficiency. One defect would lead to an abnormal C9 protein, with replacement of a cysteine by a glycine (C98G). The second defect is a premature stop codon at amino acid 406 which would lead to a truncated C9. However, at least one of two abnormal proteins was present in the circulation of the proband at 0·2% of normal C9 concentration. In this study, the abnormal protein was shown to have a molecular weight approximately equal to that of normal C9, and to carry the binding site for monoclonal antibody (mAb) Mc42 which is known to react with an epitope at amino acid positions 412–426, distal to 406. Therefore, the subtotal C9 protein carries the C98G defect. The protein was incorporated into the terminal complement complex, and was active in haemolytic, bactericidal and lipopolysaccharide release assays. A quantitative haemolytic assay indicated even slightly greater haemolytic efficiency than normal C9. Epitope mapping with six antihuman C9 mAbs showed the abnormal protein to react to these antibodies in the same way as normal C9. However, none of these mAbs have epitopes within the lipoprotein receptor A module, where the C98G defect is located. The role of this region in C9 functionality is still unclear. In conclusion, we have shown that the lack of a cysteine led to the production of a protein present in the circulation at very much reduced levels, but which was fully functionally active

The use of electroporation in developmental biology

Chapter 139-1During the formation of a complex organism, cells divide, die, migrate, and differentiate. Biologists have established tools to observe those phenomena but also to change their course, which subsequently enables to infer causal relationships between various events occurring in different cell groups. More precisely, present approaches mostly rely on modifications of gene expression. For instance, cells are labeled with fluorescent proteins and tracked within the embryo, molecular signals are switched on and off to perturb regulatory pathways. Importantly, in all those experiments, the exogenous genetic material must be delivered at the right place and with the appropriate timing: requirements that can both be fulfilled by electroporation. After 15 years of constant refinement, this technique has now superseded methods like viral infection, microinjection, and lipofection. Applications encompass a large number of model organisms, targeted anatomical structures, and molecular biology techniques