Heterochromatin, histone modifications, and nuclear architecture in disease vectors

Sharakhov, Igor V.; Sharakhova, Maria V.

doi:10.1016/j.cois.2015.05.003

Cited by 25 publications

(16 citation statements)

References 60 publications

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“…Another factor influencing the greater scaffold length in An. albimanus was the lower repeat content (only 2%), relative to all sequenced species of Anopheles (Neafsey et al 2015; Sharakhov and Sharakhova 2015). …”

Section: Discussionmentioning

confidence: 86%

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The Physical Genome Mapping ofAnopheles albimanusCorrected Scaffold Misassemblies and Identified Interarm Rearrangements in GenusAnopheles

Artemov

Peery

et al. 2017

G3 Genes|Genomes|Genetics

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The genome of the Neotropical malaria vector Anopheles albimanus was sequenced as part of the 16 Anopheles Genomes Project published in 2015. The draft assembly of this species consisted of 204 scaffolds with an N50 scaffold size of 18.1 Mb and a total assembly size of 170.5 Mb. It was among the smallest genomes with the longest scaffolds in the 16 Anopheles species cluster, making An. albimanus the logical choice for anchoring the genome assembly to chromosomes. In this study, we developed a high-resolution cytogenetic photomap with completely straightened polytene chromosomes from the salivary glands of the mosquito larvae. Based on this photomap, we constructed a chromosome-based genome assembly using fluorescent in situ hybridization of PCR-amplified DNA probes. Our physical mapping, assisted by an ortholog-based bioinformatics approach, identified and corrected nine misassemblies in five large genomic scaffolds. Misassemblies mostly occurred in junctions between contigs. Our comparative analysis of scaffolds with the An. gambiae genome detected multiple genetic exchanges between pericentromeric regions of chromosomal arms caused by partial-arm translocations. The final map consists of 40 ordered genomic scaffolds and corrected fragments of misassembled scaffolds. The An. albimanus physical map comprises 98.2% of the total genome assembly and represents the most complete genome map among mosquito species. This study demonstrates that physical mapping is a powerful tool for correcting errors in draft genome assemblies and for creating chromosome-anchored reference genomes.

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Section: Discussionmentioning

confidence: 86%

“…In addition, An. albimanus has one of the smallest genome sizes (170.5 Mb) and the lowest repeat content (only 2%) among mosquito species (Neafsey et al 2015; Sharakhov and Sharakhova 2015). The An.…”

mentioning

confidence: 99%

The Physical Genome Mapping ofAnopheles albimanusCorrected Scaffold Misassemblies and Identified Interarm Rearrangements in GenusAnopheles

Artemov

Peery

et al. 2017

G3 Genes|Genomes|Genetics

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“…This research approach should be feasible, given that functional genes and their protein products in the sialome appear to be under various degrees of selection, as inferred by species differences in biological characteristics, such as autogeny, biting behavior (i.e., ornithophily and zoophily including anthropophily), vectorial capacity, and biochemical activity of factors in the coagulation pathway [ 46 ], and because of their suitability as informative heterologous cDNA probes. Applications also are possible for the interdiction of simuliid vector sialomes of human onchocerciasis and their products during parasite transmission [ 17 , 45 ]; similar possibilities also hold for other vector-group sialomes, such as those of mosquitoes [ 47 ].…”

Section: Discussionmentioning

confidence: 99%

Chromosomal Translocations in Black Flies (Diptera: Simuliidae)—Facilitators of Adaptive Radiation?

2016

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A macrogenomic investigation of a Holarctic clade of black flies—the Simulium cholodkovskii lineage—provided a platform to explore the implications of a unique, synapomorphic whole-arm interchange in the evolution of black flies. Nearly 60 structural rearrangements were discovered in the polytene complement of the lineage, including 15 common to all 138 analyzed individuals, relative to the central sequence for the entire subgenus Simulium. Three species were represented, of which two Palearctic entities (Simulium cholodkovskii and S. decimatum) were sympatric; an absence of hybrids confirmed their reproductive isolation. A third (Nearctic) entity had nonhomologous sex chromosomes, relative to the other species, and is considered a separate species, for which the name Simulium nigricoxum is revalidated. A cytophylogeny is inferred and indicates that the two Palearctic taxa are sister species and these, in turn, are the sister group of the Nearctic species. The rise of the S. cholodkovskii lineage encompassed complex chromosomal and genomic restructuring phenomena associated with speciation in black flies, viz. expression of one and the same rearrangement as polymorphic, fixed, or sex linked in different species; taxon-specific differentiation of sex chromosomes; and reciprocal translocation of chromosome arms. The translocation is hypothesized to have occurred early in male spermatogonia, with the translocated chromosomal complement being transmitted to the X- and Y-bearing sperm during spermatogenesis, resulting in alternate disjunction of viable F1 translocation heterozygotes and the eventual formation of more viable and selectable F2 translocation homozygous progeny. Of 11 or 12 independently derived whole-arm interchanges known in the family Simuliidae, at least six are associated with subsequent speciation events, suggesting a facilitating role of translocations in adaptive radiations. The findings are discussed in the context of potential structural and functional interactions for future genomic research.

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“…As gene expression can be regulated by various factors including heterochromatin proximity and RNA modi cations, various studies have examined the role of histone and RNA modi cations in invertebrates [8]. Currently, it appears that histone modi cations, speci cally methylation, are closely related to changes in DNA methylation.…”

Section: Introductionmentioning

confidence: 99%

Larval Metal Pollutant Exposure Alters the Epigenetic Architecture of the Major Malaria Vector Anopheles Arabiensis (Diptera: Culicidae)

Jeanrenaud¹,

Brooke²,

Oliver³

2020

Preprint

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BackgroundAnopheles arabiensis (a member of the An. gambiae species complex) is a major vector of malaria. These mosquitoes typically breed in clean bodies of water, but can also utilise polluted waters. Although this expands their breeding range, adaptation to breeding in polluted waters necessitates coping with a large amount of environmental stress in the form of exposure to heavy metal pollutants. Environmental stress can induce heritable changes to an organism without altering the basal genetic code. This occurs by rapid changes in the regulatory elements associated with nucleic acids that result in changes in patterns of gene expression and silencing. This is known as epigenetic regulation. There is currently little information on epigenetic regulation in An. arabiensis. The aim of this study was to examine whether exposure to metal pollutants at the larval stage induced alterations of epigenetic markers resulting in phenotypic changes in insecticide susceptible and resistant laboratory strains of An. arabiensis. ResultsThere was a marked difference in the phenotypic response in adult mosquitoes of the insecticide susceptible strain compared to that of its’ resistant counterpart. The susceptible strain showed reduced fertility and fecundity in response to epigenetic manipulation. For males and females of the resistant strain, exposure to nucleic acid modifying drugs typically increased their tolerance to insecticides. In the insecticide susceptible strain, regulatory signals associated with gene silencing were increased, while those associated with gene expression were reduced in response to heavy metal exposure. By contrast, the insecticide resistant strain showed a decrease in signatures associated with gene silencing as well as an increase in signatures associate with chromatin remodelling. ConclusionsLarval exposure to heavy metal contaminants can result in heritable changes in gene expression. These data suggest that exposure to the same pollutants can result in different biological outcomes in insecticide susceptible and resistant adult An. arabiensis, and that these changes are reflected in their respective global? epigenetic signatures.

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Heterochromatin, histone modifications, and nuclear architecture in disease vectors

Cited by 25 publications

References 60 publications

The Physical Genome Mapping ofAnopheles albimanusCorrected Scaffold Misassemblies and Identified Interarm Rearrangements in GenusAnopheles

The Physical Genome Mapping ofAnopheles albimanusCorrected Scaffold Misassemblies and Identified Interarm Rearrangements in GenusAnopheles

Chromosomal Translocations in Black Flies (Diptera: Simuliidae)—Facilitators of Adaptive Radiation?

Larval Metal Pollutant Exposure Alters the Epigenetic Architecture of the Major Malaria Vector Anopheles Arabiensis (Diptera: Culicidae)

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