Characterization of simple sequence repeats (SSRs) from Phlebotomus papatasi (Diptera: Psychodidae) expressed sequence tags (ESTs)

<p>Abstract</p> <p>Background</p> <p><it>Phlebotomus papatasi </it>is a natural vector of <it>Leishmania major</it>, which causes cutaneous leishmaniasis in many countries. Simple sequence repeats (SSRs), or microsatellites, are common in eukaryotic genomes and are short, repeated nucleotide sequence elements arrayed in tandem and flanked by non-repetitive regions. The enrichment methods used previously for finding new microsatellite loci in sand flies remain laborious and time consuming; <it>in silico </it>mining, which includes retrieval and screening of microsatellites from large amounts of sequence data from sequence data bases using microsatellite search tools can yield many new candidate markers.</p> <p>Results</p> <p>Simple sequence repeats (SSRs) were characterized in <it>P. papatasi </it>expressed sequence tags (ESTs) derived from a public database, National Center for Biotechnology Information (NCBI). A total of 42,784 sequences were mined, and 1,499 SSRs were identified with a frequency of 3.5% and an average density of 15.55 kb per SSR. Dinucleotide motifs were the most common SSRs, accounting for 67% followed by tri-, tetra-, and penta-nucleotide repeats, accounting for 31.1%, 1.5%, and 0.1%, respectively. The length of microsatellites varied from 5 to 16 repeats. Dinucleotide types; AG and CT have the highest frequency. Dinucleotide SSR-ESTs are relatively biased toward an excess of (AX)n repeats and a low GC base content. Forty primer pairs were designed based on motif lengths for further experimental validation.</p> <p>Conclusion</p> <p>The first large-scale survey of SSRs derived from <it>P. papatasi </it>is presented; dinucleotide SSRs identified are more frequent than other types. EST data mining is an effective strategy to identify functional microsatellites in <it>P. papatasi</it>.</p

Bionomics of phlebotomine sand flies (Diptera: Psychodidae) in the province of Al-Baha, Saudi Arabia

The bionomics of phlebotomine sand flies (Diptera: Psychodidae) were studied for two successive years (January 1996-December 1997) at 12 collecting stations representing six sectors of the province of Al-Baha, Saudi Arabia. The predominant species was Phlebotomus bergeroti (41.7%), followed by lesser numbers of Phlebotomus sergenti (11%), Phlebotomus arabicus (10.6%), Sergentomyia tiberiadis (10.5%), Phlebotomus papatasi (10.2%), Sergentomyia antennata (9.6%), Phlebotomus alexandri (3%), Phlebotomus orientalis (2.3%) and Sergentomyia clydei (1.1%). The distribution of the collected species including species that are elsewhere known to act as vectors of human cutaneous leishmaniasis were distributed across different altitudes in Al-Baha. P. bergeroti, P. papatasi and P. arabicus were more abundant indoors; however, P. sergenti was more abundant outdoors. Sand fly populations exhibited three patterns of seasonal abundance in terms of their monthly activity. P. bergeroti, P. sergenti and P. arabicus were found to be naturally infected with Leishmania-like flagellates at an infection rate of 0.2%