| allele |
This is a variant
form of a gene. For diploid chromosomes, there are two alleles in
the nuclear DNA (if identical, these are homozygous; if different,
these are heterozygous). Additional alleles or copies of a gene can
be complemented on an episome or integrated into the nuclear DNA in
wild-type, mutant, or floxed forms. |
|
| gene deletion by double homologous replacement |
An allele of a gene is replaced by a drug resistance marker, resulting
in deletion of the coding DNA sequence of the allele. This is performed
twice, in sequential steps, with two different drug resistance markers
to result in the replacement of two alleles of a gene, yielding a
null mutant if the gene is not essential. |
knockout (verb) |
| null mutant |
This is a parasite strain
that lacks both alleles of a gene of interest after a deletion strategy. |
knockout (noun) |
| facilitated null mutant |
Both chromosomal alleles can be deleted, but this requires
prior genetic (episomal allele) or nutritional supplementation. |
episomal rescue, conditional null mutant |
| unforced plasmid shuffle |
Drug selection for a
plasmid episome that complements a chromosomal null mutant is removed,
and the loss or retention of this plasmid is analyzed. |
plasmid cure |
| forced plasmid shuffle |
The complementing plasmid episome contains both a positive
and negative selectable marker, which allows a selection pressure
to be imposed to favor parasites that lose the episome. |
|
| inducible gene deletion |
A
parasite line is engineered to contain an allele that can be removed
by the addition of a trigger, for example, the rapamycin-induced DiCre
recombinase deletion of a floxed allele. |
|
| floxed |
Flanked by the loxP (locus of X-overP1) site, this term is used to describe alleles
of genes that can be inducibly deleted by a Cre or DiCre (inducible
dimerizable Cre) recombinase system. |
|
| complementation |
This involves the restoration
of null mutants by the addition of an extra allele of the gene of
interest (episomally or genomically) or by the addition of a nutritional
supplement in the case of a gene that encodes a metabolic enzyme. |
add back |
| episome |
A circular
DNA molecule that can be replicated independently of the nuclear or
kinetoplast DNA. |
plasmid |
