Physical Mapping of the Anopheles (Nyssorhynchus) darlingi Genomic Scaffolds.

Míriam Silva Rafael,Wanderli Pedro Tadei,Spartaco Astolfi-Filho,Giselle Moura Guimarães-Marques,Carlos Gustavo Nunes Da Silva,Leticia Cegatti Bridi,Vladimir Timoshevskiy,Igor V Sharakhov,Maria V Sharakhova,Osvaldo Marinotti,Valéria Silva Santos

doi:10.3390/insects12020164

Abstract

Simple SummaryAnopheles darlingi mosquitoes are the main vectors of malaria in the Brazilian Amazon. To assign genomic DNA sequences to chromosomes of this species, we performed fluorescence in situ hybridization of DNA probes with salivary glands polytene chromosomes. We compared the physical locations of the An. darlingi probes with homologous sequences in other Anopheles species, namely Anopheles albimanus and Anopheles gambiae. The results demonstrated that substantial genome rearrangements occurred throughout the evolutionary history of these mosquitoes. The physical mapping data can be useful for improving the structural accuracy of the An. darlingi genome assembly and for understanding the chromosomal evolution of these mosquitoes.The genome assembly of Anopheles darlingi consists of 2221 scaffolds (N50 = 115,072 bp) and has a size spanning 136.94 Mbp. This assembly represents one of the smallest genomes among Anopheles species. Anopheles darlingi genomic DNA fragments of ~37 Kb were cloned, end-sequenced, and used as probes for fluorescence in situ hybridization (FISH) with salivary gland polytene chromosomes. In total, we mapped nine DNA probes to scaffolds and autosomal arms. Comparative analysis of the An. darlingi scaffolds with homologous sequences of the Anopheles albimanus and Anopheles gambiae genomes identified chromosomal rearrangements among these species. Our results confirmed that physical mapping is a useful tool for anchoring genome assemblies to mosquito chromosomes.

Highlights

The Anopheles genus includes vector species of great importance to public health, such as those transmitting malaria parasites [1,2,3]
The main advantage of using fosmid clones for fluorescence in situ hybridization (FISH) is that the large size of labeled probes allowed us to obtain strong and specific fluorescent signals on polytene chromosomes
In most of the An. darlingi polytene chromosome preparations assayed by FISH, strong fluorescent signals were observed for the probes used in this study

Summary

Introduction

The Anopheles genus includes vector species of great importance to public health, such as those transmitting malaria parasites [1,2,3]. This genus contains seven subgenera, of which two are the focus of the present study: Nyssorhynchus Blanchard, which includes. 39 species, among them the neotropical malaria vectors An. darlingi and Anopheles albimanus, and Cellia Theobald with 224 species, including An. gambiae [4]. The importance of An. darlingi as a malaria vector spurred effort for genome sequencing, assembling and annotation [11].

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