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Mechanisms of Olfaction in Insects - ResearchSpace@Auckland ...

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Conclud<strong>in</strong>g Discussion 132<br />

a wide range <strong>of</strong> temperatures. The availability <strong>of</strong> a draft genome <strong>of</strong> E. postvittana will<br />

be the first genome for a pest member <strong>of</strong> this family and will become the model<br />

organism for tortricid pests. The availability <strong>of</strong> the genome sequence <strong>of</strong> E. postvittana<br />

should enable functional genomic studies <strong>of</strong> the moth; provide a wealth <strong>of</strong><br />

<strong>in</strong>formation on genes <strong>in</strong>volved <strong>in</strong> biological processes and <strong>in</strong> the regulation <strong>of</strong> gene<br />

expression as well as facilitate the study <strong>of</strong> the complexity <strong>of</strong> gene families. Studies <strong>of</strong><br />

host-plant specialisation for example, E. postvittana is polyphagous so genes <strong>in</strong>volved<br />

<strong>in</strong> its survival on such a wide host range, as well as prote<strong>in</strong>s <strong>in</strong>volved <strong>in</strong> food<br />

digestion <strong>in</strong> the gut <strong>of</strong> the larvae can be identified. Other target processes <strong>in</strong>clude the<br />

regulation <strong>of</strong> genes <strong>in</strong>volved <strong>in</strong> the survival <strong>of</strong> E. postvittana, such as for juvenile<br />

hormone, which have implications <strong>in</strong> physiological processes <strong>of</strong> moths can also be<br />

studied <strong>in</strong> detail. Other genes associated with the olfactory system and their regulation<br />

mechanisms could also be studied <strong>in</strong> detail. One <strong>of</strong> the major drawbacks <strong>of</strong> us<strong>in</strong>g<br />

chemical <strong>in</strong>secticides is development <strong>of</strong> resistance by the <strong>in</strong>sects. These resistance<br />

mechanisms can also be studied and better <strong>in</strong>secticide targets developed. With the<br />

availability <strong>of</strong> genomic data for more moths, the evolution <strong>of</strong> ORs can be studied. An<br />

improved set <strong>of</strong> ORs from lepidopterans can perhaps be used <strong>in</strong> phylogenetic studies<br />

to test for associations, if any, between phylogenetic relatedness and odorant b<strong>in</strong>d<strong>in</strong>g.<br />

The problem with any ab <strong>in</strong>itio whole genome assembly is the feasibility <strong>of</strong> the<br />

assembly process. E. postvittana does not have any closely related genome sequence<br />

available for mapp<strong>in</strong>g its genome to. The low cost <strong>of</strong> sequenc<strong>in</strong>g with high throughput<br />

sequenc<strong>in</strong>g platforms has the drawback <strong>of</strong> produc<strong>in</strong>g significantly short reads that are<br />

impossible to assemble ab <strong>in</strong>itio. Another problem fac<strong>in</strong>g E. postvittana genome<br />

assembly is that its genome size is unknown. B. mori genome has been shown to have<br />

large repeats and it is highly likely to be the case for E. postvittana. Assembl<strong>in</strong>g such<br />

a genome will be highly challeng<strong>in</strong>g.<br />

Fortunately for the genome sequenc<strong>in</strong>g project, a bacterial artificial chromosome<br />

(BAC) library <strong>of</strong> E. postvittana has already been constructed. BAC-end sequenc<strong>in</strong>g<br />

will enable local, smaller assemblies <strong>of</strong> <strong>in</strong>dividual BACs which can be used further to<br />

assemble longer scaffolds, thereby facilitat<strong>in</strong>g the assembly <strong>of</strong> the draft genome.<br />

Several BACs that potentially have genes for several <strong>of</strong> the putative ORs have already<br />

been identified. These BACs can be used as the start<strong>in</strong>g po<strong>in</strong>t for BAC shotgun

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