Abstract:
Tsetse flies use antennal expressed genes to navigate their environment. While most
canonical genes associated with chemoreception are annotated, potential gaps with important
antennal genes are uncharacterized in Glossina morsitans morsitans. We generated
antennae-specific transcriptomes from adult male G. m. morsitans flies fed/unfed on bloodmeal
and/or exposed to an attractant (ε-nonalactone), a repellant (δ-nonalactone) or paraffin
diluent. Using bioinformatics approach, we mapped raw reads onto G. m. morsitans geneset
from VectorBase and collected un-mapped reads (constituting the gaps in annotation).
We de novo assembled these reads (un-mapped) into transcript and identified corresponding
genes of the transcripts in G. m. morsitans gene-set and protein homologs in UniProt
protein database to further annotate the gaps. We predicted potential protein-coding gene
regions associated with these transcripts in G. m. morsitans genome, annotated/curated
these genes and identified their putative annotated orthologs/homologs in Drosophila melanogaster,
Musca domestica or Anopheles gambiae genomes. We finally evaluated differential
expression of the novel genes in relation to odor exposures relative to no-odor control
(unfed flies). About 45.21% of the sequenced reads had no corresponding transcripts within
G. m. morsitans gene-set, corresponding to the gap in existing annotation of the tsetse fly
genome. The total reads assembled into 72,428 unique transcripts, most (74.43%) of which
had no corresponding genes in the UniProt database. We annotated/curated 592 genes
from these transcripts, among which 202 were novel while 390 were improvements of existing
genes in the G. m. morsitans genome. Among the novel genes, 94 had orthologs in D.
melanogaster, M. domestica or An. gambiae while 88 had homologs in UniProt. These
orthologs were putatively associated with oxidative regulation, protein synthesis, transcriptional
and/or translational regulation, detoxification and metal ion binding, thus providing
insight into their specific roles in antennal physiological processes in male G. m. morsitans.
A novel gene (GMOY014237.R1396) was differentially expressed in response to the attractant. We thus established significant gaps in G. m. morsitans genome annotation and
identified novel male antennae-expressed genes in the genome, among which > 53% (108)
are potentially G. m. morsitans specific.
