Immunogenetic analysis of hybrid populations of the green frog complex pelophylax esculentus-ridibundus of the fauna of Ukraine - Статья

Immunogenetic analysis of hybrid populations of the green frog complex pelophylax esculentus-ridibundus of the fauna of Ukraine I. Kozynenko E. Zhalai For purposes of unravelling the development of the hybrid complex Pelophylax esculentus-ridibundus an immu- nogenetic method of skin transplantation was applied for assessing the variability of hybrids and parental species according to levels of expressed histocompatability. Animals from the different types of hybrid systems known in Ukraine were studied. For allodiploid hybrids dominance of genes of major histocompatibility complex of frog edible was established Keywords: hybrid complex Pelophylax esculentus-ridibundus, immunogenetic studies, allo-, xenotransplantation Для вирішення питань формування гібридного комплексу Pelophylax esculentus-ridibundus застосований імуногенетичний метод пересадки шкіри, який дозволяє визначати мінливість гібридів і батьківських видів за антигенами гістосумісності. Up to now this method has not lost its value in successfully determining the genetic identity of individuals. Amphibians are proved to possess a major histocompatibility complex homologous to warm-bloo-ded animals, and, therefore, can display rejection reac-tions of the immediate type, allowing the study of population structures involving immunogenetic methods of tissue transplantation [12]. In green frogs the number of alleles of the major histocompatibility complex (MHC) is one of the largest among amphibians, so the method of transplantation in this case has a potential for a high resolution [13]. In addition, another important advantage of this method is the ability to not cause any damage to frog populations as far as the studies are conducted in vivo. Goal The goal was to identify the particular structure of hybrid populations and hybrids of the complex of green frogs Pelophylax esculentus-ridibundus in Ukraine, using immunogenetic methods of skin transplantation. The objectives of the study were to: find out for the allodiploid hybrids the parent species responsible for providing the dominant set of MHC genes, estimate the distance between the parental species and the hybrids, determine whether the genome elimination related to the hybrid is linked with the dominance of the major histocompatibility complex genes of the marsh or either the edible frog. Materials and research methods Materials Experiments were conducted on the European green frog hybrid complex Pelophylax esculentus- ridibundus: P. ridibundus - marsh (R), P. esculentus - edible (L), as well as hybrid allodiploid forms of P. esculentus- ridibundus (E) from various population systems. In particular: REL - marsh, edible and hybrids, RE - marsh and hybrids, LE - edible and hybrids, E - only hybrids. Selection of the studied localities was concentrated on zones where hybridization of green frogs occurs. Middle Dnipro Basin. Populations: REL (Novo- bilychy, vicinity of Kyiv); LE (Baryshivka, Kyivska Oblast, Nizhyn, Chernihivska Oblast) and L (edible frog) (Lisnyky, Kyivska Oblast). Lower Danube. RE population (Vylkove, Ode- sa Oblast). Transcarpathian Lowland. RE population (Tseh- livka, Zakarpatska Oblast); E population: Minay (Zakarpatska Oblast, vicinity of Uzhhorod). Siverskiy Donets Basin. RE population (Haydary, Kharkivska Oblast). A total of 603 mature individuals of the green frog complex Pelophylax esculentus-ridibundus were studied. This number included 168 marsh frogs, 160 edible frogs, 275 hybrids. After the experiments, the animals released to their natural habitat. Research methods. Morphological analysis: was applied for the preliminary identification of individuals belonging to a particular species or hybrid. We used features having the greatest diagnostic value [6]. The method of transplantation of skin graft. As a basis we chose the classic method of tissue transplantation, designed for tadpoles of R. catesbeiana and modified for frogs, which completed metamorphosis [14]. After sorting the frogs on grounds of the morphological analysis and a two-week adaptation period, allo- (the exchange of grafts between animals of one species) and xenotransplantation (the same between animals of different species) was carried out.