Note that the hypotheses are related to metrics described in the sequence and assume that there is no difference between the effort required to migrate test sets across OO and AO implementations (i.e. they represent null hypotheses).
Codd also introduced the use of the lowercase Greek omega symbol to represent Null in database theory.
Together, this indicates that the aldh1a2i26, aldh1a2um22 and aldh1a2u11 mutations do not result in hypomorphic proteins, but represent null mutations.
The first four lines of Table 2 represent null hypothesis scenarios, with a risk ratio of 1.
Several mutations create a premature stop codon in the open reading frame and therefore likely represent null alleles (Table 1, Figure 1A).
Thus, the deletion mutations most likely represent null mutations, since the resulting truncated proteins are not expected to form functional complexes with ribosomes.
Further support for the idea that aldh1a2i26, aldh1a2um22 and aldh1a2u11 represent null mutations comes from rescue experiments, which indicate that the mutant proteins are not functional.
The finding that cellular clones of ico mutants that almost certainly represent null mutations develop normally and do not disrupt patterning of the eyes indicates that the function of Drosophila EF-G1 is not required in the eye and possibly other tissues.
