Biology subjects

Eiglmeier, K.

Publications and source records attributed to Eiglmeier, K..

2 recordsLinked to original sources

bioRxiv2019

The APL1 immune factor is encoded by a single ancestral gene in most Anopheles species and expanded to three paralogs with distinct function in the Anopheles gambiae complex

BackgroundThe recent reference genome assembly and annotation of the Asian malaria vector Anopheles stephensi revealed only one gene encoding the leucine-rich repeat immune factor APL1, while in Anopheles gambiae and sibling Anopheles coluzzii, APL1 factors are encoded by a family of three paralogs. The phylogeny and biological function of the unique APL1 gene in A. stephensi have not yet been specifically examined.\n\nMethodsThe APL1 locus was manually sequenced to confirm the computationally predicted single APL1 gene in A. stephensi, and APL1 evolution within Anopheles was explored by phylogenomic analysis. The single or paralogous APL1 genes were silenced in A. stephensi and A. coluzzii, respectively, followed by mosquito survival analysis, experimental infection with Plasmodium, and expression analysis.\n\nResultsAPL1 is present as a single ancestral gene in most Anopheles including A. stephensi, but has expanded to three paralogs in an African lineage that includes only the Gambiae species complex and Anopheles christyi. Silencing of the unique APL1 copy in A. stephensi results in significant mosquito mortality. Elevated mortality of APL1-depleted A. stephensi is rescued by antibiotic treatment, suggesting that bacteria are the cause of mortality, and that the unique APL1 gene is essential for host survival. Successful Plasmodium development in A. stephensi depends upon APL1 activity for protection from high host mortality, probably caused by exposure to enteric bacteria when parasites cross the midgut epithelial barrier. In contrast, silencing of all three APL1 paralogs in A. coluzzii does not result in elevated mortality, either with or without Plasmodium infection. Expression of the single APL1 gene is regulated by both the Imd and Toll immune pathways, while control by the two pathways is subdivided to different paralogs in the expanded APL1 locus.\n\nConclusionsAPL1 underwent neofunctionalization with both loss and gain of functions concomitant with expansion from a single ancestral gene to three paralogs in one lineage of African Anopheles. The evolution of an expanded APL1 gene family could be a factor contributing to the exceptional levels of malaria transmission mediated by human-feeding members of the Gambiae complex in Africa.

genetics↗

bioRxiv2018

De novo profiling of RNA viruses in Anopheles malaria vector mosquitoes from forest ecological zones in Senegal and Cambodia

BackgroundMosquitoes are colonized by a large but mostly uncharacterized natural virome of RNA viruses. Anopheles mosquitoes are efficient vectors of human malaria, and the composition and distribution of the natural RNA virome may influence the biology and immunity of Anopheles malaria vector populations.\n\nResultsAnopheles vectors of human malaria were sampled in forest village sites in Senegal and Cambodia, including Anopheles funestus, Anopheles gambiae group sp., and Anopheles coustani in Senegal, and Anopheles hyrcanus group sp., Anopheles maculatus group sp., and Anopheles dirus in Cambodia. Small and long RNA sequences were depleted of mosquito host and de novo assembled to yield non-redundant contigs longer than 500 nucleotides. Analysis of the assemblies by sequence similarity to known virus families yielded 125 novel virus sequences, 39 from Senegal Anopheles and 86 from Cambodia. Important monophyletic virus clades in the Bunyavirales and Mononegavirales orders are found in these Anopheles from Africa and Asia. Small RNA size and abundance profiles were used to cluster non-host RNA assemblies that were unclassified by sequence similarity. 39 unclassified non-redundant contigs >500 nucleotides strongly matched a pattern of classic RNAi processing of viral replication intermediates, and 1566 unclassified contigs strongly matched a pattern consistent with piRNAs. Analysis of piRNA expression in Anopheles coluzzii after infection with Onyong nyong virus (family Togaviridae) suggests that virus infection can specifically alter abundance of some piRNAs.\n\nConclusionsRNA viruses ubiquitously colonize Anopheles vectors of human malaria worldwide. At least some members of the mosquito virome are monophyletic with other arthropod viruses. However, high levels of collinearity and similarity of Anopheles viruses at the peptide level is not necessarily matched by similarity at the nucleotide level, indicating that Anopheles from Africa and Asia are colonized by closely related but clearly diverged virome members. The interplay between small RNA pathways and the virome may represent an important part of the homeostatic mechanism maintaining virome members in a commensal or nonpathogenic state, and host-virome interactions could influence variation in malaria vector competence.

genomics↗