Ⅲ-4. Radiation Chemistry & Biology

RIKEN Accel. Prog. Rep. 51 (2018)

Results of whole-genome analysis of mahogany mutant
K. Tsuneizumi,∗1 H. Ichida,∗1 R. Morita,∗1 and T. Abe∗1
Heavy-ion-beam mutagenesis is generally recognized
as an eﬀective method for mutation breeding.1,2) Although this method was greatly successful with plants,
its application is limited for animals. Therefore, weplan to acquire more basic data to set up optimal conditions for the heavy-ion-beam irradiation system by using
Drosophila melanogaster (fruit ﬂy) as the model.
In our previous study, we determined the suitable condition for the large-scale screening of mutant lines ofheavy-ion-beam mutagenesis.3) To elucidate the biological eﬀect of heavy-ion-beam irradiation on the genome,
we established several mutants that expressed typicalphenotypes on eyes, wings, bodies, and bristles by acarbon-ion beam irradiation.
In this report, we show the analysis of data obtained
from the whole-genome sequence of the mahogany (mah)mutant. The mutant eye color is darker than that of thewild type (Figs. 1a, b). This mutant line was establishedby the condition with 50 keV/µm linear energy transfer
at 10 Gy dose level. Whole genome analysis revealed
that the causal mutation of mah was a large deletion(Fig. 1c). An open reading frame of mah is 1,581 bp
and a 387 bp deletion was observed in the ﬁrst exon ofa mah gene (Fig. 1c). An in-frame deletion produces amutated Mahogany protein from which 129 amino acidresidues were removed (Fig. 1c).
The role of the Mahogany protein (Mah) has an unknown function. InterPro is a freely available database                  

TTCCCATTTGTCACGCTGCCG
81 82 83 84 85 86 87
PheProPheValThrLeuPro           

GGAAGTCCAAAGCACATGCGG
210211212213214215216
GlySerProLysHisMetArg

Fig. 1. Phenotype of the mahogany mutant and the result ofwhole-genome analysis.
a) Wild type eye color is vivid red. b) The mutanteye color becomes darker than that of the wild type. c)
The alignments of genome and protein sequences at startand end sites of the deletion. The top line indicates thecDNA sequence. The middle line indicates the numbersof amino acid residues. The bottom line indicates aminoacid sequence. The red texts represent deleted regions.
∗1  



Fig. 2. Diagrams of protein domain analysis using InterProand deleted Mahogany protein.
a) A result data of domain analysis of Mahogany protein using InterPro database. The red box highlights thedeleted three transmembrane domains. b) A diagram ofwild type and deleted proteins of Mahogany. Full length
Mahogany protein consist of 527 amino acid residues.
The numbers indicate the numbers of amino acid residuesof the proteins. The deleted protein lacks 129 amino acidresidues (87–215).

used to classify protein sequences into families and topredict the presence of important domains and sites.4)
InterPro analysis of the predicted protein Mah identiﬁed
11 transmembrane helices and a conserved domain foundin amino acid transporters (Fig. 2a). The deleted protein
lacks three putative transmembrane domains (Figs. 2a,b). Both the amounts of ommochrome pigments andpteridine pigments are decreased in classical mah mutants.5) These results indicate that Mah function is related to both pigments transport in eye ommatidia.
Chemical mutagen mostly introduces point mutations
into genomic DNA. In this report, we conﬁrmed thatheavy-ion-beam mutagenesis has diverse mutations, forexample small insertions, point mutations, small deletions, and large deletions, in the animal genome. Currently, we are analyzing other mutants. The data will
be helpful for the elucidation of the biological eﬀect ofheavy-ion-beam irradiation to the animal genome.
References

1) T. Abe et al., in Plant Mutation Breeding and Biotechnology, edited by Q. Y. Shu et al., (CABI, Oxfordshire,2012), pp. 99.
2) A. Tanaka et al., J. Radiat. Res. 51, 223 (2010).
3) K. Tsuneizumi et al., RIKEN Accel. Prog. Rep. 49, 253(2016).
4) A. Mitchell et al., Nucleic Acids Res. 43, D213 (2015).
5) J. Ferre et al., Biochem. Genet. 24, 545 (1986).

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