Any variation that results in a decrease in the characteristic expression of a gene product, as detected by antibody staining, compared to control animals.
Variations in the form or composition of a structure in the cell nucleus which contains the genetic material encoded as DNA and surrounded by histone proteins and other regulatory elements compared to control. In C. elegans the normal cell contains 5 pairs of 'autosomes' and one or two X chromosomes (Wormatlas).