The novel circular RNA CircMef2c is positively associated with muscle growth in Nile tilapia.

Muscle growth in teleosts is a complex biological process orchestrated by numerous protein-coding genes and non-coding RNAs. A few recent studies suggest that circRNAs are involved in teleost myogenesis, but the molecular networks involved remain poorly understood. In this study, an integrative omics approach was used to determine myogenic circRNAs in Nile tilapia by quantifying and comparing the expression profile of mRNAs, miRNAs, and circRNAs in fast muscle from full-sib fish with distinct growth rates. There were 1947 mRNAs, 9 miRNAs, and 4 circRNAs differentially expressed between fast- and slow-growing individuals. These miRNAs can regulate myogenic genes and have binding sites for the novel circRNA circMef2c. Our data indicate that circMef2c may interact with three miRNAs and 65 differentially expressed mRNAs to form multiple competing endogenous RNA networks that regulate growth, thus providing novel insights into the role of circRNAs in the regulation of muscle growth in teleosts.

CircPrime: a web-based platform for design of specific circular RNA primers.

BACKGROUND: Circular RNAs (circRNAs) are covalently closed-loop RNAs with critical regulatory roles in cells. Tens of thousands of circRNAs have been unveiled due to the recent advances in high throughput RNA sequencing technologies and bioinformatic tools development. At the same time, polymerase chain reaction (PCR) cross-validation for circRNAs predicted by bioinformatic tools remains an essential part of any circRNA study before publication. RESULTS: Here, we present the CircPrime web-based platform, providing a user-friendly solution for DNA primer design and thermocycling conditions for circRNA identification with routine PCR methods. CONCLUSIONS: User-friendly CircPrime web platform ( http://circprime.elgene.net/ ) works with outputs of the most popular bioinformatic predictors of circRNAs to design specific circular RNA primers. CircPrime works with circRNA coordinates and any reference genome from the National Center for Biotechnology Information database).

Caucasian treasure: Genomics sheds light on the evolution of half-extinct Sevan trout, Salmo ischchan, species flock.

Five ecologically and phenotypically divergent ecomorphs of the genus Salmo are known from a landlocked alpine lake in the Caucasus, Lake Sevan. It is an example of sympatric diversification within a species-rich lineage with predominate mode of speciation being allopatric. The diversification of Sevan trouts was accompanied by spawning resource partitioning. Four lacustrine ecomorphs with different temporal-spatial spawning strategies and divergent morphology and coloration evolved along with a fifth ecomorph, brook trout, inhabiting the tributaries. Unfortunately, the Sevan trout diversity was almost destroyed by human activity, with two ecomorphs becoming extinct in the 1980s. We performed reconstruction of the evolutionary history of Sevan trouts based on high-throughput sequencing of both contemporary and historical DNA (∼ 50 y.o.) of all Sevan trout ecomorphs. Our study of complete mitogenomes along with genome-wide SNP data revealed the monophyly of four lacustrine ecomorphs and local brook trout, all derived from the anadromous form Caspian salmon, S. caspius. The species tree suggests a scenario of stepwise evolution from riverine to lacustrine spawning. Three genomic clusters were revealed, of which two refer to the riverine and lacustrine spawners within the flock of Sevan trouts (with FST value = 0.069). A few SNP outliers under selection were discovered that could be responsible for assortative mating based on visual recognition. The Holocene climatic oscillations and the desiccation of tributaries could have played an important role in the origin of lacustrine spawning. The relationships between lacustrine ecomorphs were not yet fully resolved. This radiation warrants further investigation.

New Cherry-Adapted Plum Pox Virus Phylogroups Discovered in Russia.

Plum pox virus (PPV) is the most pathogenic virus of stone fruit crops worldwide. Unusual PPV isolates were discovered on sour cherry (Prunus cerasus L.) and steppe cherry (P. fruticosa Pall.) in the Republic of Tatarstan and the Middle Ural region, Russia. They induced typical sharka symptoms and tested positive for PPV by ELISA and RT-PCR, but were not detected by PCR using known strain-specific primers. Their complete genomes were determined using high-throughput sequencing. Phylogenetic analysis allocated new isolates to four clearly distinguished lineages (SC, TAT, Y, Tat-26) within a cluster of PPV cherry-adapted strains. The phylogroups SC and TAT had 84.5 to 86.9% average nucleotide identity to each other and strain CR, with which they comprised a common subcluster. Isolates from the Middle Ural region (group Y) were closer to strain C, sharing 96.9% identity. The fourth lineage is represented by the isolate Tat-26, which was a recombinant of strain CR and C isolates as major and minor parents, respectively. These results show that the genetic diversity of PPV is higher than thought and may contribute to a better understanding of the origin and evolution of cherry-adapted strains of the virus. P. fruticosa was reported as a new natural PPV host for the first time.

Insulin Receptor-Related Receptor Regulates the Rate of Early Development in Xenopus laevis.

The orphan insulin receptor-related receptor (IRR) encoded by insrr gene is the third member of the insulin receptor family, also including the insulin receptor (IR) and the insulin-like growth factor receptor (IGF-1R). IRR is the extracellular alkaline medium sensor. In mice, insrr is expressed only in small populations of cells in specific tissues, which contain extracorporeal liquids of extreme pH. In particular, IRR regulates the metabolic bicarbonate excess in the kidney. In contrast, the role of IRR during Xenopus laevis embryogenesis is unknown, although insrr is highly expressed in frog embryos. Here, we examined the insrr function during the Xenopus laevis early development by the morpholino-induced knockdown. We demonstrated that insrr downregulation leads to development retardation, which can be restored by the incubation of embryos in an alkaline medium. Using bulk RNA-seq of embryos at the middle neurula stage, we showed that insrr downregulation elicited a general shift of expression towards genes specifically expressed before and at the onset of gastrulation. At the same time, alkali treatment partially restored the expression of the neurula-specific genes. Thus, our results demonstrate the critical role of insrr in the regulation of the early development rate in Xenopus laevis.

First report of fig mosaic virus on fig in Russia.

Fig mosaic virus (FMV) (genus Emaravirus in the family Fimoviridae) is considered the etiological agent of fig mosaic disease (FMD) that is recorded in most of the fig growing areas with an average global infection rate of 33%. The multipartite FMV genome is comprised of six negative monocistronic ssRNAs, each of which is separately encapsidated (Preising et al. 2020). Although FMD-like symptoms, which include mosaic, chlorotic ringspots, and oak leaf patterns, were observed in approximately a third of 400 fig accessions in the Nikita Botanical Gardens, Yalta, Russia (Mitrofanova et al. 2016), FMV has not been identified as the causal agent of the disease. In June of 2020, total RNA was isolated from symptomatic leaves of 59 thirty two-year-old trees representing 31 local and 27 introduced Ficus carica L. cultivars and a single F. pseudocarica Miq. tree using RNeasy Plant Mini kit (Qiagen, USA). FMV was tested by RT-PCR using primer sets E5 (Elbeaino et al. 2009) and EMARAVGP (Walia et al. 2009), which amplify a 302-bp fragment of RNA1 and a 468-bp fragment of RNA2, respectively. PCR products of the expected sizes were generated in all samples, indicating a high FMV incidence in the plantings. The genome sequences of FMV isolates from F. carica cvs. Bleuet, Kraps di Hersh, Smena, Temri, and F. pseudocarica (Fig. S1) were determined by high-throughput sequencing on MiSec Illumina platform. Double-stranded RNA was isolated from FMV-positive leaves using Viral Gene-spin™ Viral DNA/RNA Extraction Kit (iNtRON, Korea), followed by cDNA library preparation with the NEBNext® Ultra™ II RNA Library Prep Kit (New England Biolabs, USA). In average, 695,000 quality-filtered 150 bp pair-ended reads per a library were produced and used in a de novo assembly using metaSpades program version 3.14 (Nurk et al. 2017). In each of five samples, BLASTn analysis found six FMV-related contigs. The contigs spanned 99 to 100% of corresponding genomic segments of the most closely related isolates. In addition to FMV, fig cryptic virus-related contigs were also detected in some samples. The FMV contigs covering RNA1 to RNA6 had the highest identity to corresponding genomic segments of isolates AM941711 (96.5 to 96.6%), FM864225 (94.4 to 94.6%), FM991954 (97.9 to 98.2%), AB697863 (96.4 to 96.6%), AB697879 (93.3 to 93.4%), and AB697895 (95.4 to 97.0%), respectively. Five Russian isolates shared 99.2 to 100% nucleotide sequence identity, depending on the genomic segment. Their sequences were deposited in GenBank under accession numbers MW201216 to MW201230 and MW208662 to MW208676. Phylogenetic analysis of six ORFs showed that ORF1 to ORF3 and ORF6 of the Russian isolates clustered with FMV isolates from Italy while ORF4 grouped with the isolate JTT-Pa (AB697863) from Japan (Fig. S2). ORF5 of the Russian isolates formed a separate cluster with the isolates SB1 and SB2 from Serbia and JTT-Vi from Japan (AB697879 to AB697884). Incongruency of phylogenetic relationship among the genomic segments suggests reassortment among ancestors of the Russian FMV isolates. In addition, similar to the SB1, SB2 and JTT-Vi, ORF5 of the Russian isolates encodes a protein of 486 amino acid (aa) residues in contrast to the corresponding protein of Italian isolates consisting of 502 aa. To the best of our knowledge, this is the first report of FMV in Russia. This finding not only expands the information on the geographical distribution of FMV, but also extends knowledge on F. pseudocarica as a natural host of the virus.

Kaiso Regulates DNA Methylation Homeostasis.

Gain and loss of DNA methylation in cells is a dynamic process that tends to achieve an equilibrium. Many factors are involved in maintaining the balance between DNA methylation and demethylation. Previously, it was shown that methyl-DNA protein Kaiso may attract NCoR, SMRT repressive complexes affecting histone modifications. On the other hand, the deficiency of Kaiso resulted in reduced methylation of ICR in H19/Igf2 locus and Oct4 promoter in mouse embryonic fibroblasts. However, nothing is known about how Kaiso influences DNA methylation at the genome level. Here we show that deficiency of Kaiso led to whole-genome hypermethylation, using Kaiso deficient human renal cancer cell line obtained via CRISPR/CAS9 genome editing. However, Kaiso serves to protect genic regions, enhancers, and regions with a low level of histone modifications from demethylation. We detected hypomethylation of binding sites for Oct4 and Nanog in Kaiso deficient cells. Kaiso immunoprecipitated with de novo DNA methyltransferases DNMT3a/3b, but not with maintenance methyltransferase DNMT1. Thus, Kaiso may attract methyltransferases to surrounding regions and modulate genome methylation in renal cancer cells apart from being methyl DNA binding protein.

Molecular phylogeny of the extinct Steller's sea cow and other Sirenia species based on their complete mitochondrial genomes.

The Steller's sea cow - Hydrodamalis gigas (Dugongidae: Sirenia) - is an extinct herbivorous marine mammal which inhabited the North Pacific Ocean during the Pleistocene and Holocene. H. gigas was the largest member of the Sirenia order and disappeared in the middle of the 18th century. Here, we present the complete sequence of the mitochondrial genome of this extinct animal. The Steller's sea cow mitochondrial DNA (mtDNA) is 16,872 base pairs (bp) in length and contains a set of mitochondrial genes typical for mammals. Phylogenetic analysis based on complete mitochondrial genomes of the sirenian species allows accurate assessment of the degree of their mitogenomic diversification during millions of years of evolution.

Koban culture genome-wide and archeological data open the bridge between Bronze and Iron Ages in the North Caucasus.

The North Caucasus played a key role during the ancient colonization of Eurasia and the formation of its cultural and genetic ancestry. Previous archeogenetic studies described a relative genetic and cultural continuity of ancient Caucasus societies, since the Eneolithic period. The Koban culture, which formed in the Late Bronze Age on the North Caucasian highlands, is considered as a cultural "bridge" between the ancient and modern autochthonous peoples of the Caucasus. Here, we discuss the place of this archeological culture and its representatives in the genetic orbit of Caucasian cultures using genome-wide SNP data from five individuals of the Koban culture and one individual of the early Alanic culture as well as previously published genomic data of ancient and modern North Caucasus individuals. Ancient DNA analysis shows that an ancient individual from Klin-Yar III, who was previously described as male, was in fact a female. Additional studies on well-preserved ancient human specimens are necessary to determine the level of local mobility and kinship between individuals in ancient societies of North Caucasus. Further studies with a larger sample size will allow us gain a deeper understanding of this topic.

Metagenomic profiling of viral and microbial communities from the pox lesions of lumpy skin disease virus and sheeppox virus-infected hosts.

Introduction: It has been recognized that capripoxvirus infections have a strong cutaneous tropism with the manifestation of skin lesions in the form of nodules and scabs in the respective hosts, followed by necrosis and sloughing off. Considering that the skin microbiota is a complex community of commensal bacteria, fungi and viruses that are influenced by infections leading to pathological states, there is no evidence on how the skin microbiome is affected during capripoxvirus pathogenesis. Methods: In this study, shotgun metagenomic sequencing was used to investigate the microbiome in pox lesions from hosts infected with lumpy skin disease virus and sheep pox virus. Results: The analysis revealed a high degree of variability in bacterial community structures across affected skin samples, indicating the importance of specific commensal microorganisms colonizing individual hosts. The most common and abundant bacteria found in scab samples were Fusobacterium necrophorum, Streptococcus dysgalactiae, Helcococcus ovis and Trueperella pyogenes, irrespective of host. Bacterial reads belonging to the genera Moraxella, Mannheimia, Corynebacterium, Staphylococcus and Micrococcus were identified. Discussion: This study is the first to investigate capripox virus-associated changes in the skin microbiome using whole-genome metagenomic profiling. The findings will provide a basis for further investigation into capripoxvirus pathogenesis. In addition, this study highlights the challenge of selecting an optimal bioinformatics approach for the analysis of metagenomic data in clinical and veterinary practice. For example, direct classification of reads using a kmer-based algorithm resulted in a significant number of systematic false positives, which may be attributed to the peculiarities of the algorithm and database selection. On the contrary, the process of de novo assembly requires a large number of target reads from the symbiotic microbial community. In this work, the obtained sequencing data were processed by three different approaches, including direct classification of reads based on k-mers, mapping of reads to a marker gene database, and de novo assembly and binning of metagenomic contigs. The advantages and disadvantages of these techniques and their practicality in veterinary settings are discussed in relation to the results obtained.

First Report and Complete Genome Characterization of Cherry Virus A and Little Cherry Virus 1 from Russia.

Virus diseases affect the yield and fruit quality and shorten the productive life of stone fruits (Prunus spp. in the family Rosaceae). Of over fifty known viruses infecting these crops, cherry virus A (CVA) is among the most common, and little cherry virus 1 (LChV1) is one of the most economically important. Using high-throughput sequencing, full-length genomes of CVA and LChV1 isolates, found on interspecies hybrids in the Prunus collection of the Nikita Botanical Gardens, Russia, were sequenced, assembled, and characterized. CVA was found in the P. cerasifera × P. armeniaca hybrid and in phylogenetic analysis clustered with non-cherry virus isolates. The LChV1 isolate Stepnoe was detected in ((P. cerasifera Ehrh. × P. armeniaca L.) × P. brigantiaca Vill.) trihybrid suggesting that both P. cerasifera and P. brigantiaca potentially can be the LChV1 hosts. The isolate Stepnoe was most closely related to the Greece isolate G15_3 from sweet cherry, sharing 77.3% identity at the nucleotide level. Possibly, the highly divergent Russian isolate represents one more phylogroup of this virus. This is the first report of CVA and LChV1 from Russia, expanding the information on their geographical distribution and genetic diversity.

Genetic Diversity of Common Olive (Olea europaea L.) Cultivars from Nikita Botanical Gardens Collection Revealed Using RAD-Seq Method.

In different countries, interest in the commercial cultivation of the olive has recently greatly increased, which has led to the expansion of its range. The Crimean Peninsula is the northern limit of the common olive (Olea europaea L.) range. A unique collection of common olive's cultivars and hybrids has been collected in the Nikitsky Botanical Gardens (NBG). The aim of this study was to assess the genetic diversity of 151 samples (total of several biological replicates of 46 olive cultivars including 29 introduced and 11 indigenous genotypes) using the ddRAD sequencing method. Structural analysis showed that the studied samples are divided into ten groups, each of which mainly includes cultivars of the same origin. Cultivars introduced to the Crimean Peninsula from different regions formed separate groups, while local cultivars joined different groups depending on their origin. Cultivars of Crimean origin contain admixtures of mainly Italian and Caucasian cultivars' genotypes. Our study showed that the significant number of Crimean cultivars contains an admixture of the Italian cultivar "Coreggiolo". Genetic analysis confirmed the synonymy for the cv. "Otur" and "Nikitskaya 2", but not for the other four putative synonyms. Our results revealed the genetic diversity of the olive collection of NBG and provided references for future research studies, especially in selection studies for breeding programs.

Ancient DNA of the Don-Hares Assumes the Existence of Two Distinct Mitochondrial Clades in Northeast Asia.

Paleoclimatic changes during the Pleistocene-Holocene transition is suggested as a main factor that led to species extinction, including the woolly mammoth (Mammuthus primigenius), Steller's sea cow (Hydrodamalis gigas) and the Don-hare (Lepus tanaiticus). These species inhabited the territory of Eurasia during the Holocene, but eventually went extinct. The Don-hare is an extinct species of the genus Lepus (Leporidae, Lagomorpha), which lived in the Late Pleistocene-Early Holocene in Eastern Europe and Northern Asia. For a long time, the Don-hare was considered a separate species, but at the same time, its species status was disputed, taking into account both morphological data and mitochondrial DNA. In this study, mitochondrial genomes of five Don-hares, whose remains were found on the territory of Northeastern Eurasia were reconstructed. Firstly, we confirm the phylogenetic proximity of the "young" specimens of Don-hare and mountain or white hare, and secondly, that samples older than 39 Kya form a completely distinct mitochondrial clade.

Characterization of Divergent Grapevine Badnavirus 1 Isolates Found on Different Fig Species (Ficus spp.).

Fig mosaic disease is spread worldwide and is believed to have a viral etiology. Divergent isolates of grapevine badnavirus 1 (GBV1), named fGBV1, were discovered on Ficus carica, F. palmata, F. virgata, and F. afghanistanica in the fig germplasm collection of the Nikita Botanical Gardens, Russia, expanding the list of viruses infecting this crop. The complete genomes of five fGBV1 isolates from F. carica and F. palmata trees were determined using high-throughput and Sanger sequencing. The genomes comprised 7283 base pairs, contained four overlapping open reading frames, were 99.7 to 99.9% identical to each other, and related to GBV1 (83.2% identity). The reverse transcriptase RNase H genome regions of fGBV1 and GBV1 share 84.6% identity, indicating that fGBV1 is a divergent isolate of GBV1, which was found on the new natural hosts from a different family (Moraceae). Further, fGBV1-specific primers were developed to detect the virus using RT-PCR. Survey of 47 trees, belonging to four fig species and 14 local and introduced F. carica cultivars, showed the high fGBV1 prevalence in the collection (93.6%), including trees with no obvious symptoms of fig mosaic disease.

A de novo genome assembly of cultivated Prunus persica cv. 'Sovetskiy'.

Prunus persica is one of the main stone fruit crops in Crimea and southern Russia. The P. persica genome has recently been sequenced and annotated in good quality. However, for a deeper assessment of the peach genome, it is necessary to include in the research other cultivars that are in the collection of the Nikitsky Botanical Garden. The cultivars of the Nikitsky Botanical Garden are unique and differ from Western European and American ones, as they are derived from cultivars and forms originating from Central Asian, North Caucasian, Transcaucasian and Eastern European countries. In this paper, we present the assembly of the P. persica cv. 'Sovetskiy' genome obtained using Oxford Nanopore long reads and Illumina short reads by hybrid assembly methods. The assembled genome of P. persica cv. 'Sovetskiy' is 206.26 MB in 226 scaffolds, with N50 24 Mb, including 8 chromosomes. It contains 27140 coding genes, 26973 (99.38%) of which are annotated in at least one functional database. More than 36.05% of the genome regions were identified as repeating elements.

Intergeneric hybridization of two stickleback species leads to introgression of membrane-associated genes and invasive TE expansion.

Interspecific hybridization has occurred relatively frequently during the evolution of vertebrates. This process usually abolishes reproductive isolation between the parental species. Moreover, it results in the exchange of genetic material and can lead to hybridogenic speciation. Hybridization between species has predominately been observed at the interspecific level, whereas intergeneric hybridization is rarer. Here, using whole-genome sequencing analysis, we describe clear and reliable signals of intergeneric introgression between the three-spined stickleback (Gasterosteus aculeatus) and its distant mostly freshwater relative the nine-spined stickleback (Pungitius pungitius) that inhabit northwestern Russia. Through comparative analysis, we demonstrate that such introgression phenomena apparently take place in the moderate-salinity White Sea basin, although it is not detected in Japanese sea stickleback populations. Bioinformatical analysis of the sites influenced by introgression showed that they are located near transposable elements, whereas those in protein-coding sequences are mostly found in membrane-associated and alternative splicing-related genes.

Non-GCB Diffuse Large B-Cell Lymphoma With an Atypical Disease Course: A Case Report and Clinical Exome Analysis.

Diffuse large B-cell lymphoma (DLBCL) is the most common lymphoid tumor among other non-Hodgkin lymphomas (30-40% of all cases). This type of lymphoma is characterized by significant differences in treatment response and the heterogeneity of clinical traits. Approximately 60% of patients are cured using standard chemotherapy (CT), while in 10-15% of cases, the tumor is characterized by an extremely aggressive course and resistance to even the most high-dose programs with autologous stem cell transplantation (auto-SCT). The activated B-cell (ABC) subtype of DLBCL is characterized by poor prognosis. Here, we describe a clinical case of diffuse ABC-DLBCL with an atypical disease course. Complete remission was achieved after four courses of CT, followed by autologous hematopoietic stem cell transplantation (auto-HSCT). However, early relapse occurred 2 months after the completion of treatment. According to the results of cytogenetic studies, significant chromosome breakdowns were observed. Exome sequencing allowed for the detection of several novel mutations that affect components of the NOTCH2 and NF-κB signaling pathways, a number of epigenetic regulators (KMT2D, CREBBP, EP300, ARID1A, MEF2B), as well as members of the immunoglobulin superfamily (CD58 and CD70). Whether these mutations were the result of therapy or were originally present in the lymphoid tumor remains unclear. Nevertheless, the introduction of genomic technologies into clinical practice is important for making a diagnosis and developing a DLBCL treatment regimen with the use of targeted drugs.

Ancient DNA Reveals Maternal Philopatry of the Northeast Eurasian Brown Bear (Ursus arctos) Population during the Holocene.

Significant palaeoecological and paleoclimatic changes that took place during Late Pleistocene-Early Holocene transition are considered important factors that led to megafauna extinctions. Unlike many other species, the brown bear (Ursus arctos) has survived this geological time. Despite the fact that several mitochondrial DNA clades of brown bears became extinct at the end of the Pleistocene, this species is still widely distributed in Northeast Eurasia. Here, using the ancient DNA analysis of a brown bear individual that inhabited Northeast Asia in the Middle Holocene (3460 ± 40 years BP) and comparative phylogenetic analysis, we show a significant mitochondrial DNA similarity of the studied specimen with modern brown bears inhabiting Yakutia and Chukotka. In this study, we clearly demonstrate the maternal philopatry of the Northeastern Eurasian U. arctos population during the several thousand years of the Holocene.

The complete chloroplast genome sequence of cultivated Prunus persica cv. 'Sovetskiy'.

The peach (Prunus persica L. Batsch) is one of the important stone fruit crops in the Crimea Peninsula and the southern part of Russia. The complete chloroplast genome of the peach cultivar 'Sovetskiy' is published in this paper. The chloroplast genome size is 157,756 bp. It contains 126 genes, including 81 protein-coding genes (PCGs), eight ribosomal RNA (rRNA) genes, and 37 transfer RNA (tRNA) genes. The chloroplast genome also contains a large single-copy region of 85,960 bp, a small single-copy (SSC) region of 19,045 bp, and two inverted repeats regions of 26,375 bp and 26,372 bp. The overall base composition of the genome in descending order is 31.2% - A, 32.1% - T, 18.7% - C, and 18.0% - G. The total GC content of the chloroplast genome is 36.7%. Maximum-likelihood phylogenetic analysis involving nine chloroplast genomes of the Prunus genus revealed a separate cluster for P. persica and its possible landrace - P. ferganensis.

Genomic evidence supports the introgression between two sympatric stickleback species inhabiting the White Sea basin.

Interspecies hybridization is driven by a complex interplay of factors where introgression plays an important role. In the present study, the transfer of genetic material, between two quite distant fish species from different genera, through spontaneous hybridization was documented with dedicated molecular and bioinformatics tools. We investigate the genomic landscape of putative stickleback-relative introgression by carefully analyzing the tractable transposable elements (TE) on the admixed genome of some individuals of two sympatric stickleback species inhabiting northwestern Russia, namely the three-spined (Gasterosteus aculeatus) and the nine-spined (Pungitius pungitius) sticklebacks. Our data revealed that unique TE amplification types exist, supporting our proposed hypothesis that infers on the interspecific introgression. By running a restriction site-associated DNA sequencing (RAD-Seq) with eight samples of G. aculeatus and P. pungitius and subjecting further the results to a contrasting analysis by variated bioinformatic tools, we identified the related introgression-linked markers. The admixture nature observed in a single sample of the nine-spined stickleback demonstrated the possible traces of remote introgression between these two species. Our work reveals the potential that introgression has on providing particular variants at a high-frequency speed while linking blocks of sequence with multiple functional mutations. However, even though our results are of significant interest, an increased number of samples displaying the introgression are required to further ascertain our conclusions.