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<doi_batch xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://www.crossref.org/schema/5.3.1" xmlns:jats="http://www.ncbi.nlm.nih.gov/JATS1" xmlns:fr="http://www.crossref.org/fundref.xsd" xmlns:ai="http://www.crossref.org/AccessIndicators.xsd" version="5.3.1"><head><doi_batch_id>NONE</doi_batch_id><timestamp>20260618171703890</timestamp><depositor><depositor_name>Immanuel Kant Baltic Federal University</depositor_name><email_address>no-reply@journals.kantiana.ru</email_address></depositor><registrant>Immanuel Kant Baltic Federal University</registrant></head><body><journal><journal_metadata><full_title>IKBFU's Vestnik. Series: Natural Sciences</full_title><issn media_type="print">2500-3208</issn></journal_metadata><journal_issue><publication_date media_type="print"><month>06</month><day>18</day><year>2026</year></publication_date><journal_volume><volume>1</volume></journal_volume><issue>1</issue></journal_issue><journal_article publication_type="full_text"><titles><title>Urban Planning Development of Königsberg (Modern Kaliningrad) in the 19th Century: Regulatory Acts and Features</title><original_language_title>Градостроительное развитие Кёнигсберга (современного Калининграда) в XIX веке: нормативные акты и особенности</original_language_title></titles><contributors><person_name sequence="first" contributor_role="author"><given_name>A. V.</given_name><surname>Levchenkov</surname><affiliations><institution><institution_name>Immanuel Kant Baltic Federal University</institution_name></institution></affiliations><ORCID>https://orcid.org/0000-0002-0418-9459</ORCID></person_name></contributors><jats:abstract><jats:p>The 19th century in Europe in general, and in Prussia in particular, marked a period of the formation of a legislative framework for urban planning at both the state and local levels, as a precursor to modern spatial planning. From the initial selective regulation of urban development (fire-prevention measures, etc.), by the beginning of the 20th century a system of regulatory frameworks for managing urban development had been established. At the same time, there is no clear understanding of which processes and regulations influenced, albeit only partially due to the events of the Second World War, the formation of the present-day urban landscape of Kaliningrad. The factors influencing urban development are examined, and urban growth is assessed from the perspective of urban planning (maximum development parameters, functional zoning, etc.), including the building regulations in force and the relevant concepts applied. The balance between the public interest represented by the municipality and the private interest represented by developers is analyzed.</jats:p></jats:abstract><publication_date media_type="print"><month>06</month><day>18</day><year>2026</year></publication_date><pages><first_page>5</first_page><last_page>22</last_page></pages><doi_data><doi>10.5922/vestniknat-2026-2-1</doi><resource>https://journals.kantiana.ru/en/vestnik/nature/16082/94410/</resource></doi_data></journal_article><journal_article publication_type="full_text"><titles><title>The Conceptual Provisions for the Point-Index Assessment of Ore Resources in the Northern Economic Region of Russia</title><original_language_title>Концептуальные положения балльно-индексной оценки рудных ресурсов Северного экономического района России</original_language_title></titles><contributors><person_name sequence="first" contributor_role="author"><given_name>F. M.</given_name><surname>Renni</surname><affiliations><institution><institution_name>Saint Petersburg State University</institution_name></institution></affiliations><ORCID>https://orcid.org/0000-0001-8195-5818</ORCID></person_name></contributors><jats:abstract><jats:p>The purpose of the study is the experimental development of a score-index methodology for assessing iron ore and aluminum raw material deposits as components of mineral resources, as well as its testing in the territories comprising the Northern Economic Region of Russia. The study draws upon extensive statistical and factual material contained in regulatory and legal documents, as well as in scholarly sources. The main characteristics of mineral resources are presented as of 2022. It is shown that the score-index assessment methodology is aimed at analyzing a resource as a system of components expressed through various properties of natural bodies. With regard to deposits of iron ore, bauxites, and the nepheline component of complex apatite-nepheline ores, a staged assignment of scores and indices reflecting the qualitative and quantitative characteristics of resources according to special scales is substantiated. The scores obtained in this way are successively summed, and, on the basis of the resulting final value, the efficiency and prospects for the further development of the deposits are determined. It has been established that the most profitable deposits are represented by nepheline ores in the Murmansk Region and bauxites in the Komi Republic, while iron ores located in the Republic of Karelia and the Murmansk Region demonstrate medium profitability. Using the author’s methodology, which takes into account the most important characteristics of mineral resources and the economic-geographical factors affecting the development of the mining industry, the mineral resource potential of the regions was calculated: the Murmansk Region and the Komi Republic possess the highest potential, whereas the Republic of Karelia and the Arkhangelsk Region demonstrate lower values. The obtained results may be used in strategic spatial planning and in managing the regional development of the resource-based economy of the Northern Economic Region of Russia.</jats:p></jats:abstract><publication_date media_type="print"><month>06</month><day>18</day><year>2026</year></publication_date><pages><first_page>23</first_page><last_page>41</last_page></pages><doi_data><doi>10.5922/vestniknat-2026-2-2</doi><resource>https://journals.kantiana.ru/en/vestnik/nature/16082/94412/</resource></doi_data></journal_article><journal_article publication_type="full_text"><titles><title>The role of entrepreneurship in the revitalization of small towns in the non-chernozem region (on the example of Borovichi, Novgorod region)</title><original_language_title>Роль предпринимательства в ревитализации малых городов нечерноземья (на примере г. Боровичи Новгородской области)</original_language_title></titles><contributors><person_name sequence="first" contributor_role="author"><given_name>V. G.</given_name><surname>Karasev</surname><affiliations><institution><institution_name>Saint Petersburg State University</institution_name></institution></affiliations><ORCID>https://orcid.org/0009-0005-9559-129X</ORCID></person_name></contributors><jats:abstract><jats:p>The study is aimed at examining small towns in the Non-Chernozem zone of Russia, with particular attention focused on the town of Borovichi in the Novgorod Region, whose socio-economic development dynamics largely resemble those of other similar towns (depopulation, reduction of human capital, contraction of the labor market, etc.). The paper presents a multi-scale analysis of the socio-economic development problems of small towns in the Non-Chernozem zone. The history of the formation and evolution of the functional development of Borovichi is analyzed in order to identify the predetermined nature of contemporary trends in spatial development. To determine the role of entrepreneurship in revitalizing the town, an assessment of the current state and development prospects of business was carried out in both sectoral and territorial dimensions. Based on official statistical data and expert interviews conducted by the author in February 2025, qualitative and quantitative characteristics of small and medium-sized enterprises (SMEs) in Borovichi are presented. Drawing on field observations and the analysis of project documentation, the main areas and actors of environmental revitalization are identified, and cases of socio-economic revitalization under the auspices of business are examined. It has been established that SMEs differing in sectoral affiliation and scale exert different influences on the processes of urban space revitalization, while the effectiveness of entrepreneurial activity is largely determined by the combination of formal and informal institutional conditions ensuring the development of business as a driver of positive urban transformations.</jats:p></jats:abstract><publication_date media_type="print"><month>06</month><day>18</day><year>2026</year></publication_date><pages><first_page>42</first_page><last_page>58</last_page></pages><doi_data><doi>10.5922/vestniknat-2026-2-3</doi><resource>https://journals.kantiana.ru/en/vestnik/nature/16082/94414/</resource></doi_data></journal_article><journal_article publication_type="full_text"><titles><title>Formation of the Acoustic Environment in Residential Areas of Kaliningrad under the Influence of Traffic Flows</title><original_language_title>Формирование акустической среды Калининграда под воздействием транспортных потоков</original_language_title></titles><contributors><person_name sequence="first" contributor_role="author"><given_name>I. D.</given_name><surname>Nagurnaya</surname><affiliations><institution><institution_name>Environmental Centre for Administration and Technology in Kaliningrad</institution_name></institution><institution><institution_name>Immanuel Kant Baltic Federal University</institution_name></institution></affiliations></person_name><person_name sequence="additional" contributor_role="author"><given_name>I. I.</given_name><surname>Volkova</surname><affiliations><institution><institution_name>Immanuel Kant Baltic Federal University</institution_name></institution></affiliations></person_name><person_name sequence="additional" contributor_role="author"><given_name>T. V.</given_name><surname>Shaplygina</surname><affiliations><institution><institution_name>Immanuel Kant Baltic Federal University</institution_name></institution></affiliations></person_name></contributors><publication_date media_type="print"><month>06</month><day>18</day><year>2026</year></publication_date><pages><first_page>59</first_page><last_page>78</last_page></pages><doi_data><doi>10.5922/vestniknat-2026-2-4</doi><resource>https://journals.kantiana.ru/en/vestnik/nature/16083/94417/</resource></doi_data></journal_article><journal_article publication_type="full_text"><titles><title>Experimental assessment of the influence of certain aspects of baltic herring spawning on the model species of cladocerans</title><original_language_title>Экспериментальная оценка влияния отдельных аспектов нереста балтийской сельди на модельный вид ветвистоусых ракообразных</original_language_title></titles><contributors><person_name sequence="first" contributor_role="author"><given_name>Ju. Ju.</given_name><surname>Polunina</surname><affiliations><institution><institution_name>Institute of Oceanology P. P. Shirshov</institution_name></institution><institution><institution_name>Immanuel Kant Baltic Federal University</institution_name></institution></affiliations><ORCID>https://orcid.org/0000-0002-8157-9522</ORCID></person_name><person_name sequence="additional" contributor_role="author"><given_name>S. M.</given_name><surname>Nikitina</surname><affiliations><institution><institution_name>Immanuel Kant Baltic Federal University</institution_name></institution></affiliations></person_name><person_name sequence="additional" contributor_role="author"><given_name>А. V.</given_name><surname>Gushchin</surname><affiliations><institution><institution_name>Institute of Oceanology P. P. Shirshov</institution_name></institution></affiliations></person_name></contributors><jats:abstract><jats:p>Experiments were conducted to investigate the influence of gametes and water collected from spawning aggregations of the Baltic herring Clupea harengus membras in the Vistula Lagoon on the survival, growth, molting frequency, number of eggs in the brood chamber, and offspring production of the model planktonic crustacean species Daphnia magna. In the first series of experiments, a fixed volume of a suspension of gametes from male and female Baltic herring (gonads at stage V of maturity) was added to the experimental containers and compared with the control. In the second series of experiments, daphnids were acclimated to brackish water (up to 3 PSU), after which they were used in the control and experimental groups to assess the effect of water collected from Baltic herring spawning grounds in the lagoon area. In media containing Baltic herring gametes, the fecundity of daphnids was significantly lower than the control values. The growth of daphnids was stimulated by the addition of female gonads (average molting frequency 114 %), whereas the addition of male gonads inhibited growth (54 %) relative to the control (84 %). Water collected from the Baltic herring spawning grounds did not exert a significant effect on the growth or molting frequency of daphnids, but it significantly stimulated the production of parthenogenetic eggs in the brood chamber of daphnids (control: 7.7; experiment: 13.0 eggs/female/day). A hypothesis is proposed that Baltic herring gametes, as well as biologically active compounds entering the waters of the Vistula Lagoon during spawning, may influence the growth and fecundity of natural populations of cladoceran crustaceans.</jats:p></jats:abstract><publication_date media_type="print"><month>06</month><day>18</day><year>2026</year></publication_date><pages><first_page>79</first_page><last_page>94</last_page></pages><doi_data><doi>10.5922/vestniknat-2026-2-5</doi><resource>https://journals.kantiana.ru/en/vestnik/nature/16083/94418/</resource></doi_data></journal_article><journal_article publication_type="full_text"><titles><title>Development and synthesis of a non-specific immunomodulating peptidomimetic</title><original_language_title>Разработка и синтез пептидомиметика неспецифического иммуномодулирующего действия</original_language_title></titles><contributors><person_name sequence="first" contributor_role="author"><given_name>S. L.</given_name><surname>Tikhonov</surname><affiliations><institution><institution_name>Ural State Agrarian University</institution_name></institution><institution><institution_name>Ural State Forestry University</institution_name></institution><institution><institution_name>V. M. Gorbatov Federal Research Center of Food Systems of the Russian Academy of Sciences</institution_name></institution></affiliations><ORCID>https://orcid.org/0000-0003-4863-9834</ORCID></person_name><person_name sequence="additional" contributor_role="author"><given_name>N. V.</given_name><surname>Tikhonov</surname><affiliations><institution><institution_name>Ural State Agrarian University</institution_name></institution></affiliations><ORCID>https://orcid.org/0000-0001-5841-1791</ORCID></person_name><person_name sequence="additional" contributor_role="author"><given_name>M. S.</given_name><surname>Timofeeva</surname><affiliations><institution><institution_name>Ural State Agrarian University</institution_name></institution></affiliations><ORCID>https://orcid.org/0000-0001-7760-1427</ORCID></person_name><person_name sequence="additional" contributor_role="author"><given_name>S. V.</given_name><surname>Shikhalev</surname><affiliations><institution><institution_name>Ural State University of Economics</institution_name></institution></affiliations><ORCID>https://orcid.org/0000-0002-9236-7154</ORCID></person_name></contributors><jats:abstract><jats:p>The use of peptides is associated with certain challenges. Due to proteolytic instability and a short plasma half-life, peptides require the development and application of specialized delivery systems, which often limits their use to parenteral administration routes. Low bioavailability following oral administration further complicates the clinical use of peptides, especially in chronic diseases requiring patient-friendly treatment regimens. The aim of the study was to develop, synthesize, and characterize a peptidomimetic for oral administration with nonspecific immunomodulatory activity, as well as to assess its cytotoxicity and effect on DC proliferation. The object of the study was a peptidomimetic designated CD-17 with the following amino acid sequence: CTSIGGAGTCPPICFFD. It was established that there are no matches between the amino acid sequence of CD-17 and known peptides or peptidomimetics, which indicates the uniqueness of the developed peptidomimetic. The physicochemical properties and structure of the peptidomimetic were predicted. According to the APD database, the total net charge of CD-17 is – 1, the peptide hydrophobicity according to the Wimley–White method (i. e., the sum of the transfer energy of the peptide without the whole residue from water to the POPC interface) is 0.86 units, the molecular weight is 1688.97 Da, the molecular formula of the peptide is C73H109N17O23S3, and the protein-binding potential (Boman index) is 0.41 kcal/mol. It was established that CD-17 is a biologically active peptidomimetic and belongs to the DILI-negative category, i. e., it is safe for the liver. Prediction of the acute oral toxicity of CD-17 in rats demonstrated that the peptidomimetic does not exhibit acute toxicity (non-toxic at doses &gt; 500 mg/ kg). The VDss of CD-17 is 0.879 with an optimal range of 0.04—20, while Fu is 89.24 % with an optimal value of ≥ 20. CD-17 demonstrates excellent CL and a moderate half-life. It was established that after three days of cultivation with the peptidomimetic, the number of DCs was 23.07 % higher (p &lt; 0.05) compared with the negative control.</jats:p></jats:abstract><publication_date media_type="print"><month>06</month><day>18</day><year>2026</year></publication_date><pages><first_page>95</first_page><last_page>107</last_page></pages><doi_data><doi>10.5922/vestniknat-2026-2-6</doi><resource>https://journals.kantiana.ru/en/vestnik/nature/16084/94425/</resource></doi_data></journal_article><journal_article publication_type="full_text"><titles><title>Synthesis of lectins by micromycetes of the genus Alternaria</title><original_language_title>Синтез лектинов микромицетами рода Alternaria</original_language_title></titles><contributors><person_name sequence="first" contributor_role="author"><given_name>M. R.</given_name><surname>Zinurov</surname><affiliations><institution><institution_name>Kazan National Research Technological University</institution_name></institution></affiliations></person_name><person_name sequence="additional" contributor_role="author"><given_name>E. E.</given_name><surname>Zinurova</surname><affiliations><institution><institution_name>FSAEI НЕ I. M. Sechenov First MSMU of МОН of Russia (Sechenovskiy University)</institution_name></institution></affiliations><ORCID>https://orcid.org/0000-0002-6639-2524</ORCID></person_name><person_name sequence="additional" contributor_role="author"><given_name>Sh. Z.</given_name><surname>Validov</surname><affiliations><institution><institution_name>FIC KazNC RAS</institution_name></institution></affiliations></person_name><person_name sequence="additional" contributor_role="author"><given_name>M. D.</given_name><surname>Frolov</surname><affiliations><institution><institution_name>FIC KazNC RAS</institution_name></institution></affiliations></person_name><person_name sequence="additional" contributor_role="author"><given_name>M. A.</given_name><surname>Sysoeva</surname><affiliations><institution><institution_name>Kazan National Research Technological University</institution_name></institution></affiliations><ORCID>https://orcid.org/0000-0003-1535-8497</ORCID></person_name><person_name sequence="additional" contributor_role="author"><given_name>T. V.</given_name><surname>Bagaeva</surname><affiliations><institution><institution_name>Kazan Federal University</institution_name></institution></affiliations><ORCID>https://orcid.org/0000-0002-1672-5052</ORCID></person_name></contributors><jats:abstract><jats:p>Using the example of 10 micromycete strains, including museum strains of Alternaria alternata, Alternaria solani and Alternaria infectoria, as well as isolates obtained from natural samples (soil, potato tubers, and wheat seeds), the ability of micromycetes of the genus Alternaria to synthesize endogenous and exogenous lectins was established. Micromycetes of the genus Alternaria are capable of synthesizing both exogenous and endogenous lectins. It was established that the lectin activity of the studied Alternaria micromycete strains is significantly lower than that of micromycetes of the genus Fusarium. Nevertheless, it was possible to increase the lectin activity titer of Alternaria micromycetes by 2—8 times through treatment of the erythrocyte surface with neuraminidase. Among the new isolates of Alternaria micromycetes, the strain Alternaria alternata 4 (grain) synthesizing lectins with the highest activity titer (512 units) was selected. To confirm its belonging to the genus Alternaria, a molecular genetic analysis was performed, which demonstrated that the obtained strain belongs to the phylum Ascomycota, class Ascomycetes, subclass Dothideomycetidae, order Pleosporales, family Pleosporaceae, species Alternaria alternata. Comparison of the activity titers of exogenous and endogenous lectins demonstrated the predominance of intracellular lectin synthesis, making these forms the most promising for further research.</jats:p></jats:abstract><publication_date media_type="print"><month>06</month><day>18</day><year>2026</year></publication_date><pages><first_page>108</first_page><last_page>118</last_page></pages><doi_data><doi>10.5922/vestniknat-2026-2-7</doi><resource>https://journals.kantiana.ru/en/vestnik/nature/16084/94428/</resource></doi_data></journal_article><journal_article publication_type="full_text"><titles><title>Assessment of Water Quality from Uncentralized Water Supply Sources in Rural Areas of the Amur Region</title><original_language_title>Оценка качества воды из источников нецентрализованного водоснабжения населенных пунктов аграрной зоны Амурской области</original_language_title></titles><contributors><person_name sequence="first" contributor_role="author"><given_name>O. V.</given_name><surname>Chagarova</surname><affiliations><institution><institution_name>Blagoveshchensk State Pedagogical University</institution_name></institution></affiliations><ORCID>https://orcid.org/0009-0006-2253-470X</ORCID></person_name><person_name sequence="additional" contributor_role="author"><given_name>O. A.</given_name><surname>Kositsyna</surname><affiliations><institution><institution_name>Blagoveshchensk State Pedagogical University</institution_name></institution></affiliations><ORCID>https://orcid.org/0009-0000-9712-3231</ORCID></person_name></contributors><jats:abstract><jats:p>The Amur Region is a major agricultural area of the Russian Far East with a high rural population density. In most cases, water from decentralized sources is used for drinking, household, and domestic purposes. The scientific literature lacks data on the current state of groundwater in the most intensively exploited part of the region, the Amur–Zeya Plain. The quality of drinking water from decentralized water supply sources in the agricultural districts (Tambovsky, Konstantinovsky, and Arkharinsky) of the Amur Region was assessed. Water samples were collected in accordance with GOST R 59024-2020 during the period from March to May 2025. The depth of the wells ranged from 90 to 250 m. The investigated sources were deep tubular wells used for individual purposes. The study of groundwater composition was carried out in the environmental chemistry laboratory of Благовещенский State Pedagogical University using the capillary electrophoresis method with the “Kapel 205” capillary electrophoresis system; cation composition was determined according to FERD 14.1:2:4.167-2000 (Federal Environmental Regulatory Documents), anion composition according to FERD 14.1:2:3:4.282-18, and pH according to RD 52.24.495-2017. The obtained results were compared with SanPiN 1.2.3685-21 standards. In the water of the settlements of Kuropatino and Arkhara, MPC exceedances for nitrites were identified, while water from Lozovoye and Kuropatino showed exceedances for lithium and potassium, respectively. Water samples from the settlements of Kositsino and Otvazhnoye contained elevated concentrations of nitrite ions and barium ions. Water collected from wells in Novopetrovka contained high concentrations of lithium and barium cations. Water from decentralized water supply sources in the village of Sadovoye did not comply with standards for six indicators. Exceedances were identified for nitrite and nitrate ions, fluorine, potassium, phosphates, and barium. In general, it should be noted that elevated concentrations of barium cations and nitrite ions were identified in the Tambovsky, Konstantinovsky, and Arkharinsky municipal districts.</jats:p></jats:abstract><publication_date media_type="print"><month>06</month><day>18</day><year>2026</year></publication_date><pages><first_page>119</first_page><last_page>128</last_page></pages><doi_data><doi>10.5922/vestniknat-2026-2-8</doi><resource>https://journals.kantiana.ru/en/vestnik/nature/16084/94429/</resource></doi_data></journal_article><journal_article publication_type="full_text"><titles><title>Genetic lability of Varroa Destructor as a factor of the epizootic process in Apis Mellifera Carpatica populations</title></titles><contributors><person_name sequence="first" contributor_role="author"><given_name>D. I.</given_name><surname>Gumerov</surname><affiliations><institution><institution_name>Kazan (Volga Region) Federal University</institution_name></institution></affiliations><ORCID>https://orcid.org/0009-0004-8265-3554</ORCID></person_name></contributors><jats:abstract><jats:p>The global decline of honey bee (Apis mellifera) populations poses a serious threat to crop pollination and global food security. Among the multiple factors causing colony weakening and loss, varroosis, an invasive disease caused by the ectoparasitic mite Varroa destructor, plays a pivotal role. Despite decades of research and various control methods, effective management of this parasite remains elusive. The aim of this work was a comprehensive analysis of the genetic structure of V. destructor populations infesting Carpathian bee colonies (A. m. carpatica) in the Republic of Tatarstan, within the framework of the parasite’s genetic lability and adaptive potential. Sequencing of the mitochondrial cox1 gene fragment and phylogenetic analysis using the Neighbor-Joining method with 103 reference sequences from GenBank were performed. The studied samples were found to belong to the Korean (K) haplotype. The identified single nucleotide polymorphism (A/T transversion) in two samples indicates intrapopulation genetic differentiation. It is shown that the genetic lability of the parasite, manifested in the existence of multiple genovars within one colony and their ability to rapidly shift dominant haplogroups under selective pressure, is an underestimated factor reducing the effectiveness of acaricide treatments and the selection of resistant bee breeds. Behavioral adaptations of the mite, including its ability to modify the host’s cuticular hydrocarbon profile and change trophic preferences depending on population density, are discussed. The obtained data substantiate the need for regular molecular genetic monitoring of V. destructor population structure as an essential element of the veterinary and sanitary surveillance system in beekeeping.</jats:p></jats:abstract><publication_date media_type="print"><month>06</month><day>18</day><year>2026</year></publication_date><pages><first_page>129</first_page><last_page>140</last_page></pages></journal_article><journal_article publication_type="full_text"><titles><title>Genetic variability and phylogeographic relations of Nosema Apis at the apiary level</title><original_language_title>Филогеографические связи Nosema Apis на уровне пасеки</original_language_title></titles><contributors><person_name sequence="first" contributor_role="author"><given_name>A. D.</given_name><surname>Sevastianova</surname><affiliations><institution><institution_name>Kazan (Volga Region) Federal University</institution_name></institution></affiliations><ORCID>https://orcid.org/0009-0005-4465-9338</ORCID></person_name><person_name sequence="additional" contributor_role="author"><given_name>M. N.</given_name><surname>Mukminov</surname><affiliations><institution><institution_name>Kazan (Volga Region) Federal University</institution_name></institution></affiliations><ORCID>https://orcid.org/0000-0002-5996-0271</ORCID></person_name></contributors><jats:abstract><jats:p>The results of a comprehensive analysis of the genetic diversity of the microsporidian Nosema apis, the causative agent of nosemosis in honey bees (Apis mellifera), are presented using the example of a single apiary located in the Laishevsky District of the Republic of Tatarstan. Identification of the haplotypic composition of the pathogen and assessment of its phylogeographic relationships with Eurasian isolates were carried out based on the polymorphism of the polar tube protein gene PTP3. It was established that all examined bees were infected with N. apis. Sequencing and subsequent cloning of heterozygous samples revealed the presence of two amino acid variants of the PTP3 protein within a single hive. One of them completely coincided with the dominant Eurasian haplotype previously described in parasite populations from Slovenia, Spain, and Turkey. The second variant is unique to the present study and differs from the main variant by a single nonsynonymous substitution (leucine instead of proline at the position presumably corresponding to codon 112 of the protein). A weak positive correlation was identified between high invasion intensity (spore load &gt; 150 thousand spores) and the belonging of bees to hybrid forms involving the Central Russian and Grey Mountain Caucasian breeds (r = 0.25; p &lt; 0.05).</jats:p></jats:abstract><publication_date media_type="print"><month>06</month><day>18</day><year>2026</year></publication_date><pages><first_page>141</first_page><last_page>153</last_page></pages><doi_data><doi>10.5922/vestniknat-2026-2-10</doi><resource>https://journals.kantiana.ru/en/vestnik/nature/16084/94433/</resource></doi_data></journal_article></journal></body></doi_batch>
