Phylogenomics revealed migration routes and adaptive radiation timing of Holarctic malaria mosquito species of the Maculipennis Group

BACKGROUND

Phylogenetic analyses of closely related species of mosquitoes are important for better understanding the evolution of traits contributing to transmission of vector-borne diseases. Six out of 41 dominant malaria vectors of the genus Anopheles in the world belong to the Maculipennis Group, which is subdivided into two Nearctic subgroups (Freeborni and Quadrimaculatus) and one Palearctic (Maculipennis) subgroup. Although previous studies considered the Nearctic subgroups as ancestral, details about their relationship with the Palearctic subgroup, and their migration times and routes from North America to Eurasia remain controversial. The Palearctic species An. beklemishevi is currently included in the Nearctic Quadrimaculatus subgroup adding to the uncertainties in mosquito systematics.

RESULTS

To reconstruct historic relationships in the Maculipennis Group, we conducted a phylogenomic analysis of 11 Palearctic and 2 Nearctic species based on sequences of 1271 orthologous genes. The analysis indicated that the Palearctic species An. beklemishevi clusters together with other Eurasian species and represents a basal lineage among them. Also, An. beklemishevi is related more closely to An. freeborni, which inhabits the Western United States, rather than to An. quadrimaculatus, a species from the Eastern United States. The time-calibrated tree suggests a migration of mosquitoes in the Maculipennis Group from North America to Eurasia about 20-25 million years ago through the Bering Land Bridge. A Hybridcheck analysis demonstrated highly significant signatures of introgression events between allopatric species An. labranchiae and An. beklemishevi. The analysis also identified ancestral introgression events between An. sacharovi and its Nearctic relative An. freeborni despite their current geographic isolation. The reconstructed phylogeny suggests that vector competence and the ability to enter complete diapause during winter evolved independently in different lineages of the Maculipennis Group.

CONCLUSIONS

Our phylogenomic analyses reveal migration routes and adaptive radiation timing of Holarctic malaria vectors and strongly support the inclusion of An. beklemishevi into the Maculipennis Subgroup. Detailed knowledge of the evolutionary history of the Maculipennis Subgroup provides a framework for examining the genomic changes related to ecological adaptation and susceptibility to human pathogens. These genomic variations may inform researchers about similar changes in the future providing insights into the patterns of disease transmission in Eurasia.

[Factors Affecting the Stability of the Trimer of 2'-Deoxyuridine 5'-Triphosphate Nucleotide Hydrolase from Escherichia coli]

2'-Deoxyuridine 5'-triphosphate nucleotide hydrolase (Dut) hydrolyzes dUTP to dUMP and pyrophosphate to prevent erroneous incorporation of dUMP from the dUTP metabolic pool into DNA. Dut is considered as a promising pharmacological target for antimetabolite therapy. Enzymatically active Dut is a trimer that binds the substrate at the interface between the subunits. High-speed nanoscale differential scanning fluorimetry (nanoDSF) was used to study how various physicochemical factors affect the stability of the Escherichia coli Dut trimer. Unlike with monomeric proteins, thermal unfolding of Dut occurred in two steps, the first one corresponding to dissociation of the trimer into monomeric subunits. Hydrophobic interactions and hydrogen bonds at the interfaces between the subunits were found to contribute most to trimer stabilization. The binding of nucleotide ligands partly stabilized the Dut trimer. In general, nanoDSF is a convenient assay for screening low-molecular-weight compounds for their ability to destabilize the active Dut trimer.

[Therapeutic areas of the Republic of Tyva]

The need to expand the resort and recreational potential in the Siberian Federal District is due to the growing need for sanatorium treatment and rehabilitation of the population. Balneological studies conducted in different regions of Siberia make it possible to position these territories as promising for resort and recreational activities.

OBJECTIVE

Comprehensive integral assessment of the resort and recreational potential of the treatment areas of the Republic of Tyva.

MATERIAL AND METHODS

Taking into account the requirements of the guidelines "Bioclimatic passport of the medical and recreational areas" No. 96/226, approved by the Ministry of Health of Russia on February 7, 1997, an integral medical and climatic assessment of the territories of the medical and recreational areas of the Republic of Tyva was carried out. The assessment of the quality of water resources was carried out in accordance with the criteria of the methodological recommendations "Control of the quality and safety of mineral waters by chemical and microbiological indicators" No. 96/225, approved by the Ministry of Health of Russia on 07.04.1997. The typification of water resources is given in accordance with GOST R 54316-2011 "Natural mineral drinking waters".

RESULTS

The territory of the Republic of Tyva has the richest reserves of unique therapeutic hydro-mineral resources, and the existing features of landscape and climatic conditions determine the prospects for their widespread use. The surveyed areas are located on mid-mountain and low-mountain landscapes with favorable bioclimatic conditions for the organization of climate treatment and recreation, especially in the warm season. The prospects for the development of climate-balneological and climate-mud resorts in Tuva are shown, especially in terms of medical and health tourism.

CONCLUSION

A detailed database has been developed on the components of the resort and recreational potential (bioclimate, mineral waters, therapeutic mud) of the treatment areas of Tuva. The data obtained formed the basis of proposals for updating the register of resorts and health-improving areas of the Siberian Federal District, which is formed on the basis of the results of many years of research.

[The medical-recreational and balneotherapeutic regions of the Krasnoyarsk Territory]

BACKGROUND

the creation of the efficient system of the spa and health resort-based health care for the population of the entire territory of the Russian Federation requires the systematic evaluation and protection of the natural resources of country as a basis for the further development of the health resort and recreation facilities in different regions.

AIM

The objective of the present study was to estimate the possibilities of expansion of the health resort and recreational activities based on the rational exploitation of the natural resources of the medical-recreational and balneotherapeutic areas of the Krasnoyarsk Territory.

METHODS

The inspection of the medical-recreational and balneotherapeutic regions of the southern part of the Krasnoyarsk Territory with the evaluation of the medicinal and raw materials resources of the spa and health resort facilities located in this area. The comprehensive assessment of the landscape and climatic conditions of the territory was performed in compliance with the methodological recommendations No 96/226 «The bioclimatic passport of the medical-recreational and balneotherapeutic region» approved by the Ministry of Health of the Russian Federation as of 7 February 1997. The quality of water bodies/sources was carried out in conformity with the criteria envisaged by the methodological recommendations No 96/225 «Quality and safety control of mineral waters based on their chemical and microbiological characteristics» approved by the Ministry of Health of the Russian Federation as of 7 April 1997. Water typing was performed in accordance with GOST R 54316-2011 «Natural drinking mineral waters».

RESULTS

The medical-recreational and balneotherapeutic regions in southern part of the Krasnoyarsk Territory are notable for the great variety of mountainous, forest and steppe landscape forms with their favorable bioclimatic conditions and unique resources of therapeutic muds and mineral carbonic waters. The area is characterized by the great potential for the further development of the climatic spa and health resort facilities, and the improvement of the health care service for both children's and adult populations based on the rational use of the local landscape and climatic factors available at the territories occupied by the spa and health resort facilities of the balneotherapeutic profile. The prospects for the further expansion of medical and recreational tourism are discussed.

CONCLUSIONS

This article was designed to systematize the available data characterizing the balneotherapeutic and recreational conditions of the medical-recreational regions of the southern part of the Krasnoyarsk Territory with special reference to the value of their natural resources, such as bioclimate, mineral waters, therapeutic muds, etc., for their inclusion in the registry of the areas possessed of the great health-improving potential based on the rational nature use and environmental management programs.

A standard photomap of ovarian nurse cell chromosomes and inversion polymorphism in Anopheles beklemishevi

Background

Anopheles beklemishevi is a member of the Maculipennis group of malaria mosquitoes that has the most northern distribution among other members of the group. Although a cytogenetic map for the larval salivary gland chromosomes of this species has been developed, a high-quality standard cytogenetic photomap that enables genomics and population genetics studies of this mosquito at the adult stage is still lacking.

Methods

In this study, a cytogenetic map for the polytene chromosomes of An. beklemishevi from ovarian nurse cells was developed using high-resolution digital imaging from field collected mosquitoes. PCR-amplified DNA probes for fluorescence in situ hybridization (FISH) were designed based on the genome of An. atroparvus. The DNA probe obtained by microdissection procedures from the breakpoint region was labelled in a DOP-PCR reaction. Population analysis was performed on 371 specimens collected in 18 locations.

Results

We report the development of a high-quality standard photomap for the polytene chromosomes from ovarian nurse cells of An. beklemishevi. To confirm the suitability of the map for physical mapping, several PCR-amplified probes were mapped to the chromosomes of An. beklemishevi using FISH. In addition, we identified and mapped DNA probes to flanking regions of the breakpoints of two inversions on chromosome X of this species. Inversion polymorphism was determined in 13 geographically distant populations of An. beklemishevi. Four polymorphic inversions were detected. The positions of common chromosomal inversions were indicated on the map.

Conclusions

The study constructed a standard photomap for ovarian nurse cell chromosomes of An. beklemishevi and tested its suitability for physical genome mapping and population studies. Cytogenetic analysis determined inversion polymorphism in natural populations of An. beklemishevi related to this species’ adaptation.

Electronic supplementary material

The online version of this article (10.1186/s13071-018-2657-3) contains supplementary material, which is available to authorized users.

[The prospects for the further development of the Belokurikha spa and health resort territory in the Altai Krai (region)]

We undertook a balneological survey of the Belokurikha spa and health resort territory with the purpose of distinguishing and identifying the potential health-improvement areas most promising for the extension and optimization of the therapeutic, tourist and recreational activities. The assessment was focused on the characteristic of the landscape and climatic conditions of the territory, the possibilities for the development of the existing resources of mineral waters and therapeutic muds as well as for the discovery of the potential new ones. The recommendations are proposed to promote the development of different forms of tourism with special reference to its medical and health-improvement aspects. It is suggested that the territory of the «Belokurikha» resort», «Belokurikha-2» and «Belokurikha-3» health-improvement areas should be integrated into a single spa-and-health resort district of federal importance.

Mitotic-chromosome-based physical mapping of the Culex quinquefasciatus genome

The genome assembly of southern house mosquito Cx. quinquefasciatus is represented by a high number of supercontigs with no order or orientation on the chromosomes. Although cytogenetic maps for the polytene chromosomes of this mosquito have been developed, their utilization for the genome mapping remains difficult because of the low number of high-quality spreads in chromosome preparations. Therefore, a simple and robust mitotic-chromosome-based approach for the genome mapping of Cx. quinquefasciatus still needs to be developed. In this study, we performed physical mapping of 37 genomic supercontigs using fluorescent in situ hybridization on mitotic chromosomes from imaginal discs of 4th instar larvae. The genetic linkage map nomenclature was adopted for the chromosome numbering based on the direct positioning of 58 markers that were previously genetically mapped. The smallest, largest, and intermediate chromosomes were numbered as 1, 2, and 3, respectively. For idiogram development, we analyzed and described in detail the morphology and proportions of the mitotic chromosomes. Chromosomes were subdivided into 19 divisions and 72 bands of four different intensities. These idiograms were used for mapping the genomic supercontigs/genetic markers. We also determined the presence of length polymorphism in the q arm of sex-determining chromosome 1 in Cx. quinquefasciatus related to the size of ribosomal locus. Our physical mapping and previous genetic linkage mapping resulted in the chromosomal assignment of 13% of the total genome assembly to the chromosome bands. We provided the first detailed description, nomenclature, and idiograms for the mitotic chromosomes of Cx. quinquefasciatus. Further application of the approach developed in this study will help to improve the quality of the southern house mosquito genome.

Cyst geometry in the egg chambers of Calliphora erythrocephala Mg. (Diptera: Calliphoridae) ovaries

In the germarium of polytrophic ovarioles of Calliphora erythrocephala (Mg.) fly, four mitotic divisions of cystoblasts give rise to 16-cell germ-line cysts. One cell differentiates into an oocyte, while the remaining 15 cells become nurse cells. Concomitantly actin-rich ring canals are formed at the intercellular junctions. The present study considers a mutual arrangement of the ring canals formed after the second to fourth mitoses relative to the ring canal formed after the first mitotic division in different regions of the germarium and egg chambers. During the cyst formation and its movement to the posterior end of the germarium, the ring canals are displaced relative to one another, thereby giving different branching variants of the cyst. The pattern of cell interconnections becomes stable in germarium region 2b and does not change during the cyst movement along the ovariole despite the cyst polarizes and increases in size.

The changes in chromosome 6 spatial organization during chromatin polytenization in the Calliphora erythrocephala Mg. (Diptera: Calliphoridae) nurse cells

Localization of Calliphora erythrocephala chromosome 6 in a 3D nuclear space at different stages of nurse cell chromatin polytenization was analyzed by fluorescence in situ hybridization and 3D microscopy. The obtained results suggest a large-scale chromatin relocation in the C. erythrocephala nurse cell nuclei, which is accompanied by a change in the chromosome territory of chromosome 6 associated with the change in expression activity of the nucleus and formation of reticular chromatin structure. It was revealed that the relocation of chromosome 6 (nucleolus organizer chromosome) is accompanied by fragmentation of the single large nucleolus into micronucleoli, which are spread over the entire nuclear space being associated with their nucleolar organizer regions. Presumably, the chromosome 6 material during transition to a highly polytenized structure is redistributed in the nucleus so that the inactive pericentromeric regions are displaced to the nuclear periphery, while the chromosome regions carrying rDNA sequences loop out beyond the chromosome territory. Being dispersed over the entire nuclear space, rDNA sequences are likely to be amplified, thereby providing numerous small signals from the chromosome 6-specific DNA probe. Micronucleoli are formed around the actively transcribed nucleolar organizer regions.

[Analysis of sex chromosome homologies in representatives of the family Calliphoridae]

The distribution of sequences homologous to the Calliphora erythrocephala Mg. sex chromosome was studied in Protophormia terranovae R-D and Lucilia sp. The chromatin structure was found to be similar in regions containing homologous DNA sequences.

[Intranuclear dynamics of chromosome 6 in nurse cells of Calliphora erythrocephala Mg. (Diptera: Calliphoridae)]

Intranuclear dynamics of chromosome 6 in nurse cell nuclei of Calliphora erythrocephala Mg. (Diptera: Calliphoridae) was studied. The 3D FISH method was used for the first time to study chromosome territories in highly polyploid nuclei whose chromosomes undergo morphological changes. A considerable change in the intranuclear location of chromosome 6 and a morphological alteration of the chromosome territory in the course of chromatin polytenization were revealed.