Neofunctionalization driven by positive selection led to the retention of the loqs2 gene encoding an Aedes specific dsRNA binding protein

Abstract Background Mosquito borne viruses, such as dengue, Zika, yellow fever and Chikungunya, cause millions of infections every year. These viruses are mostly transmitted by two urban-adapted mosquito species, Aedes aegypti and Aedes albopictus. Although mechanistic understanding remains largely unknown, Aedes mosquitoes may have unique adaptations that lower the impact of viral infection. Recently, we reported the identification of an Aedes specific double-stranded RNA binding protein (dsRBP), named Loqs2, that is involved in the control of infection by dengue and Zika viruses in mosquitoes. Preliminary analyses suggested that the loqs2 gene is a paralog of loquacious (loqs) and r2d2, two co-factors of the RNA interference (RNAi) pathway, a major antiviral mechanism in insects. Results Here we analyzed the origin and evolution of loqs2. Our data suggest that loqs2 originated from two independent duplications of the first double-stranded RNA binding domain of loqs that occurred before the origin of the Aedes Stegomyia subgenus, around 31 million years ago. We show that the loqs2 gene is evolving under relaxed purifying selection at a faster pace than loqs, with evidence of neofunctionalization driven by positive selection. Accordingly, we observed that Loqs2 is localized mainly in the nucleus, different from R2D2 and both isoforms of Loqs that are cytoplasmic. In contrast to r2d2 and loqs, loqs2 expression is stage- and tissue-specific, restricted mostly to reproductive tissues in adult Ae. aegypti and Ae. albopictus. Transgenic mosquitoes engineered to express loqs2 ubiquitously undergo developmental arrest at larval stages that correlates with massive dysregulation of gene expression without major effects on microRNAs or other endogenous small RNAs, classically associated with RNA interference. Conclusions Our results uncover the peculiar origin and neofunctionalization of loqs2 driven by positive selection. This study shows an example of unique adaptations in Aedes mosquitoes that could ultimately help explain their effectiveness as virus vectors

Ubiquitin-specific proteases are differentially expressed throughout the Schistosoma mansoni life cycle.

Submitted by Nuzia Santos ([email protected]) on 2016-02-16T17:36:58Z No. of bitstreams: 1 Ubiquitin-specific proteases are differentially expressed throughout the Schistosoma mansoni life cycle.pdf: 10854490 bytes, checksum: ea309d46076c53adba1eaaafffeccdb4 (MD5)Approved for entry into archive by Nuzia Santos ([email protected]) on 2016-02-16T18:15:37Z (GMT) No. of bitstreams: 1 Ubiquitin-specific proteases are differentially expressed throughout the Schistosoma mansoni life cycle.pdf: 10854490 bytes, checksum: ea309d46076c53adba1eaaafffeccdb4 (MD5)Made available in DSpace on 2016-02-16T18:15:37Z (GMT). No. of bitstreams: 1 Ubiquitin-specific proteases are differentially expressed throughout the Schistosoma mansoni life cycle.pdf: 10854490 bytes, checksum: ea309d46076c53adba1eaaafffeccdb4 (MD5) Previous issue date: 2015Universidade Federal de Ouro Preto. Núcleo de Pesquisas em Ciências Biológicas. Ouro Preto, MG, BrasilUniversidade Federal de Uberlândia. Instituto de Genética e Bioquímica. Patos de Minas, MG, Brasil.Universidade Federal de Ouro Preto. Núcleo de Pesquisas em Ciências Biológicas. Ouro Preto, MG, BrasilUniversidade Federal de Ouro Preto. Núcleo de Pesquisas em Ciências Biológicas. Ouro Preto, MG, BrasilInstituto de Ciências Biomédicas Butantã.. Departamento de Fisiologia. São Paulo, SP, Brasil.Fundação Oswaldo Cruz. Centro de Pesquisas René Rachou. Belo Horizonte, MG, Brasil.Fundação Oswaldo Cruz. Centro de Pesquisas René Rachou. Belo Horizonte, MG, Brasil.Universidade de São Paulo. Faculdade de Medicina de Ribeirão Preto. São Paulo, Brasil.Universidade de São Paulo. Faculdade de Medicina de Ribeirão Preto. São Paulo, Brasil.Universidade Federal de Ouro Preto. Núcleo de Pesquisas em Ciências Biológicas. Ouro Preto, MG, BrasilUniversidade Federal de Ouro Preto. Núcleo de Pesquisas em Ciências Biológicas. Ouro Preto, MG, Brasil/Universidade Federal de Ouro Preto. Instituto de Ciências Exatas e Biológicas. Núcleo de Pesquisas em Ciências Biológicas. Departamento de Ciências Biológicas. Ouro Preto, MG, Brasil.Background: The ubiquitination process can be reversed by deubiquitinating enzymes (DUBs). These proteases are involved in ubiquitin processing, in the recovery of modified ubiquitin trapped in inactive forms, and in the recycling of ubiquitin monomers from polyubiquitinated chains. The diversity of DUB functions is illustrated by their number and variety of their catalytic domains with specific 3D architectures. DUBs can be divided into five subclasses: ubiquitin C-terminal hydrolases (UCHs), ubiquitin-specific proteases (USPs or UBPs), ovarian tumour proteases (OTUs), Machado-Joseph disease proteases (MJDs) and JAB1/MPN/Mov34 metalloenzymes (JAMMs). Methods: Considering the role that the ubiquitin-proteasome system has been shown to play during the development ofSchistosoma mansoni, our main goal was to identify and characterize SmUSPs. Here, we showed the identification of putative ubiquitin-specific proteases using bioinformatic approaches. We also evaluated the gene expression profile of representative USP family members using qRT-PCR. Results: We reported 17 USP family members in S. mansoni that present a conservation of UCH domains. Furthermore, the putativeSmUSP transcripts analysed were detected in all investigated stages, showing distinct expression during S. mansonidevelopment. The SmUSPs exhibiting high expression profiles were SmUSP7, SmUSP8, SmUSP9x and SmUSP24. Conclusion: S. mansoni USPs showed changes in expression levels for different life cycle stages indicating their involvement in cellular processes required for S. mansoni development. These data will serve as a basis for future functional studies of USPs in this parasite

A single unidirectional piRNA cluster similar to the flamenco locus is the major source of EVE-derived transcription and small RNAs in Aedes aegypti mosquitoes

Endogenous viral elements (EVEs) are found in many eukaryotic genomes. Despite considerable knowledge about genomic elements such as transposons (TEs) and retroviruses, we still lack information about non-retroviral EVEs. Aedes aegypti mosquitoes have a highly repetitive genome that is covered with EVEs. Here, we identified 129 non-retroviral EVEs in the AaegL5 version of the A. aegypti genome. These EVEs were significantly associated with TEs and preferentially located in repeat-rich clusters within intergenic regions. Genome-wide transcriptome analysis showed that most EVEs generated transcripts although only around 1.4% were sense RNAs. The majority of EVE transcription was antisense and correlated with the generation of EVE-derived small RNAs. A single genomic cluster of EVEs located in a 143 kb repetitive region in chromosome 2 contributed with 42% of antisense transcription and 45% of small RNAs derived from viral elements. This region was enriched for TE-EVE hybrids organized in the same coding strand. These generated a single long antisense transcript that correlated with the generation of phased primary PIWI-interacting RNAs (piRNAs). The putative promoter of this region had a conserved binding site for the transcription factor Cubitus interruptus, a key regulator of the flamenco locus in Drosophila melanogaster. Here, we have identified a single unidirectional piRNA cluster in the A. aegypti genome that is the major source of EVE transcription fueling the generation of antisense small RNAs in mosquitoes. We propose that this region is a flamenco-like locus in A. aegypti due to its relatedness to the major unidirectional piRNA cluster in Drosophila melanogaster

Insect-specific viruses regulate vector competence in <em>Aedes aegypti</em> mosquitoes via expression of histone H4

Aedes aegypti and Aedes albopictus are major mosquito vectors for arthropod-borne viruses (arboviruses) such as dengue (DENV) and Zika (ZIKV) viruses. Mosquitoes also carry insect-specific viruses (ISVs) that may affect the transmission of arboviruses. Here, we analyzed the global virome in urban Aedes mosquitoes and observed that two insect-specific viruses, Phasi Charoen-like virus (PCLV) and Humaita Tubiacanga virus (HTV), were the most prevalent in A. aegypti worldwide except for African cities, where transmission of arboviruses is low. Spatiotemporal analysis revealed that presence of HTV and PCLV led to a 200% increase in the chances of having DENV in wild mosquitoes. In the laboratory, we showed that HTV and PCLV prevented downregulation of histone H4, a previously unrecognized proviral host factor, and rendered mosquitoes more susceptible to DENV and ZIKV. Altogether, our data reveals a molecular basis for the regulation of A. aegypti vector competence by highly prevalent ISVs that may impact how we analyze the risk of arbovirus outbreaks

Mosquito vector competence for dengue is modulated by insect-specific viruses

International audienceAedes aegypti and A. albopictus mosquitoes are the main vectors for dengue virus (DENV) and other arboviruses, including Zika virus (ZIKV). Understanding the factors that affect transmission of arboviruses from mosquitoes to humans is a priority because it could inform public health and targeted interventions. Reasoning that interactions among viruses in the vector insect might affect transmission, we analysed the viromes of 815 urban Aedes mosquitoes collected from 12 countries worldwide. Two mosquito-specific viruses, Phasi Charoen-like virus (PCLV) and Humaita Tubiacanga virus (HTV), were the most abundant in A. aegypti worldwide. Spatiotemporal analyses of virus circulation in an endemic urban area revealed a 200% increase in chances of having DENV in wild A. aegypti mosquitoes when both HTV and PCLV were present. Using a mouse model in the laboratory, we showed that the presence of HTV and PCLV increased the ability of mosquitoes to transmit DENV and ZIKV to a vertebrate host. By transcriptomic analysis, we found that in DENV-infected mosquitoes, HTV and PCLV block the downregulation of histone H4, which we identify as an important proviral host factor in vivo

Genomic analysis of two phlebotomine sand fly vectors of Leishmania from the New and Old World

Phlebotomine sand flies are of global significance as important vectors of human disease, transmitting bacterial, viral, and protozoan pathogens, including the kinetoplastid parasites of the genus Leishmania, the causative agents of devastating diseases collectively termed leishmaniasis. More than 40 pathogenic Leishmania species are transmitted to humans by approximately 35 sand fly species in 98 countries with hundreds of millions of people at risk around the world. No approved efficacious vaccine exists for leishmaniasis and available therapeutic drugs are either toxic and/or expensive, or the parasites are becoming resistant to the more recently developed drugs. Therefore, sand fly and/or reservoir control are currently the most effective strategies to break transmission. To better understand the biology of sand flies, including the mechanisms involved in their vectorial capacity, insecticide resistance, and population structures we sequenced the genomes of two geographically widespread and important sand fly vector species: Phlebotomus papatasi, a vector of Leishmania parasites that cause cutaneous leishmaniasis, (distributed in Europe, the Middle East and North Africa) and Lutzomyia longipalpis, a vector of Leishmania parasites that cause visceral leishmaniasis (distributed across Central and South America). We categorized and curated genes involved in processes important to their roles as disease vectors, including chemosensation, blood feeding, circadian rhythm, immunity, and detoxification, as well as mobile genetic elements. We also defined gene orthology and observed micro-synteny among the genomes. Finally, we present the genetic diversity and population structure of these species in their respective geographical areas. These genomes will be a foundation on which to base future efforts to prevent vector-borne transmission of Leishmania parasites. The leishmaniases are a group of neglected tropical diseases caused by protist parasites from the Genus Leishmania. Different Leishmania species present a wide clinical profile, ranging from mild, often self-resolving cutaneous lesions that can lead to protective immunity, to severe metastatic mucosal disease, to visceral disease that is ultimately fatal. Leishmania parasites are transmitted by the bites of sand flies, and as no approved human vaccine exists, available drugs are toxic and/or expensive and parasite resistance to them is emerging, new dual control strategies to combat these diseases must be developed, combining interventions on human infections and integrated sand fly population management. Effective vector control requires a comprehensive understanding of the biology of sand flies. To this end, we sequenced and annotated the genomes of two sand fly species that are important leishmaniasis vectors from the Old and New Worlds. These genomes allow us to better understand, at the genetic level, processes important in the vector biology of these species, such as finding hosts, blood-feeding, immunity, and detoxification. These genomic resources highlight the driving forces of evolution of two major Leishmania vectors and provide foundations for future research on how to better prevent leishmaniasis by control of the sand fly vectors

Genomic analysis of two phlebotomine sand fly vectors of Leishmania from the New and Old World.

Phlebotomine sand flies are of global significance as important vectors of human disease, transmitting bacterial, viral, and protozoan pathogens, including the kinetoplastid parasites of the genus Leishmania, the causative agents of devastating diseases collectively termed leishmaniasis. More than 40 pathogenic Leishmania species are transmitted to humans by approximately 35 sand fly species in 98 countries with hundreds of millions of people at risk around the world. No approved efficacious vaccine exists for leishmaniasis and available therapeutic drugs are either toxic and/or expensive, or the parasites are becoming resistant to the more recently developed drugs. Therefore, sand fly and/or reservoir control are currently the most effective strategies to break transmission. To better understand the biology of sand flies, including the mechanisms involved in their vectorial capacity, insecticide resistance, and population structures we sequenced the genomes of two geographically widespread and important sand fly vector species: Phlebotomus papatasi, a vector of Leishmania parasites that cause cutaneous leishmaniasis, (distributed in Europe, the Middle East and North Africa) and Lutzomyia longipalpis, a vector of Leishmania parasites that cause visceral leishmaniasis (distributed across Central and South America). We categorized and curated genes involved in processes important to their roles as disease vectors, including chemosensation, blood feeding, circadian rhythm, immunity, and detoxification, as well as mobile genetic elements. We also defined gene orthology and observed micro-synteny among the genomes. Finally, we present the genetic diversity and population structure of these species in their respective geographical areas. These genomes will be a foundation on which to base future efforts to prevent vector-borne transmission of Leishmania parasites

Admixture cross validation error.

Violin plot of the cross-validation error for each of 30 replicates for each K value. (A) Phlebotomus papatasi populations. (B) Lutzomyia longipalpis populations. (TIF)</p