Title: An EST database of the Caribbean fruit fly, Anastrephas suspensa (Diptera:Tephritidae) Authors
|Xavier, Nirmala -|
|Fahong, Yu -|
|Schetelig, Marc Florian|
Submitted to: Gene
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 7, 2012
Publication Date: January 5, 2013
Citation: Xavier, N., Fahong, Y., Schetelig, M.A., Handler, A.M. 2013. An EST database of the Caribbean fruit fly, Anastrephas suspensa (Diptera:Tephritidae). Gene. 517:212-217. Interpretive Summary: Invasive tephritid fruit flies such as the Medfly, Mexfly and Olive fly are a great threat to agriculture worldwide and warrant serious pest control measures. In the currently used Sterile Insect Technique (SIT), male insects sterilized by high-dose radiation, are released into the field where they mate with fertile females and thereby reduce pest population size. To improve SIT, molecular control measures aimed at causing embryonic lethality are highly desired. A limiting factor for this is the small number of nucleotide sequence data available for tephritid species especially during embryonic development. Therefore, to increase the resources available for this stage in particular, we generated an embryonic transcriptome by high throughput 454 sequencing of the Caribbean fruit fly, Anastrepha suspensa, which is a model for tephritid pests. In addition, to identify lethal effectors for creating lethal transgenic strains, a second transcriptome was created, using embryos induced by '-irradiation to enrich for genes regulating the cell death pathway. 454 sequencing of non-irradiated and irradiated transcriptomes yielded 342,052 reads which were assembled into 95,803 sequences with 16,288 contigs and 73,568 singletons. About 31% of all assembled sequences were annotated by comparisons to the nr database, Drosophila Reference proteins and the medfly ESTs in GenBank using BLASTX or BLASTN. More than half (58%) of the annotated sequences were hits to proteins from Drosophila spp. A small number of sequences (543) with no homology to the nr database shared identity with the non-annotated transcripts of Drosophila yakuba and Drosophila pseudoobscura. Both transcriptomes contained a number of genes involved in cell death pathway, sex-determination, RNAi pathway, embryo specific genes, transposable elements and microsatellites. This study provides an insight into the embryonic development of caribflies and expands the resources available to create an effective embryonic lethality strain.
Technical Abstract: The ability to create transgenic strains of economically and medically important insect species has the potential to greatly improve existing biological control methods, which is a major goal of our laboratory at the Center for Medical, Agricultural and Veterinary Entomology, USDA, Agricultural Research Service, Gainesville, FL. For the field release of an efficient lethal strain it is desirable to test multiple strains with various regulatory regions that drive different lethal effector genes to create redundancy in lethal effect. Therefore, it is critical to discover additional lethal genes and genes that are highly expressed during embryonic development that would in turn allow isolation of their promoter regulatory region. Since the available sequence information for tephritid insects is limited, we sought to increase the dataset by high-throughput DNA sequencing to generate large scale sequence information for the embryonic development of Caribbean fruit fly, Anastrepha suspensa. In addition, to enable identification of genes associated with the programmed cell death pathway, cell death was induced in embryos by a cytotoxic stimulus ('-irradiation). Perhaps the most interesting outcome of this study is the high level of expression of genes involved in the programmed cell death pathway, which has the potential for elucidating a critical developmental pathway found in almost all organisms, as well as providing genetic reagents useful for controlling insect pest species.