Question

3.You’re interested in the genetic basis for autism spectrum disorders (ASD). To model and understand this condition, you perform genetic screens in the zebrafish Danio rerio in order to find mutations that mimic aspects of human autism phenotypes. Your screen identifies a series of 6 true-breeding mutants that have autism-like symptoms in zebrafish (and name these autism mutants aut-1 through aut-6). You cross together each of these mutants and examine their progeny (the F1 generation) and note their phenotypes in the table below.  (A is autism phenotype, N is normal wild-type zebrafish behavior, and the row and column names indicate which combination of mutants were crossed together in each case). PLEASE SHOW ALL WORK AS DETAILED AS POSSIBLE!!

aut-1   aut-2   aut-3   aut-4   aut-5   aut-6   

aut-1     A         N         N       N        N          N         

aut-2     N        A         N       A        N          N         

aut-3     N         N         A       N        N          N         

aut-4     N         A         N       A        N          N         

aut-5     N         N         N       N        A          A         

aut-6     N         N         N       N        A          A         

1. Are aut-1 through aut-6 dominant or recessive and why?

2. How many distinct genes did you find (and why)?

3. What alleles correspond to these genes?

Answer 1

When two similar looking mutants are allowed to cross and the resulting F1 progeny exhibits the WT phenotype, it shows that both the mutations are located at different loci. i.e. they are non-allelic.
When two similar looking mutants are allowed to cross and the resulting F1 progeny exhibits the mutant phenotype, it means that both the mutations are located at the same locus i.e. they are allelic to each other.

In the given case,
N = WT phenotype
A = Mutant phenotype

Complementation groups:
1. aut-1
2. aut-2 and aut-4
3. aut-3
4. aut-5 and aut-6

There are four different loci are mutated in the given set of mutants.
All the given mutants are recessive as any of the F1 progeny do not exhibit 100% phenotype.