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Aim. The rapidly evolving mitochondrial CoI gene is widely used in the molecular taxonomy of insects to identify closely related forms. Accordingly, to assess the distribution of subspecies / breeds of Apis mellifera in Ukraine, sequencing and comparison of this gene was performed for bees from different geographical regions. Methods. PCR amplification and sequencing of CoI. Results. Breed-specific mutations in the CoI gene have been identified for the Dark European, Carpathian and Ukrainian Steppe honey bees, which are widely distributed in Ukraine. It was found that the current distribution of these breeds does not correspond to the traditional zoning. Conclusions. The widespread practice of importing the genetic material of Apis mellifera from different regions of Ukraine leads to uncontrolled hybridization and represents a threat to the conservation of aboriginal breeds of honey bees.Keywords: biodiversity, mitochondrial DNA, molecular markers, cytochrome oxidase, Apis mellifera.

Genomic regions encoding 5S ribosomal RNA represent a convenient source of molecular markers. These genomic regions are composed of tandemly organized repeated units. Each unit consists of a highly conserved 5S rRNA coding region and a variable intergenic spacer (IGS). Within the IGS, regulatory elements involved in 5S rDNA transcription are located. Given that 5S rDNA is present in the genomes of all eukaryotes, this region can be used as a universal model to study molecular evolution in different taxa. Molecular studies of Lepidoptera have always been of considerable practical interest, because this group includes a large number of crop pests. Accordingly, the results of molecular studies can be used for molecular genotyping and correct identification of insect pests. Taking into account that the molecular organization and polymorphism of 5S rDNA remain still unexplored in species of the Drepanidae family, the aim of our work was to investigate the 5S rDNA of peach blossom (Thyatira batis L.), a representative of this family. The repeated unit of 5S rDNA was amplified by PCR, and the obtained DNA fragments were ligated into a plasmid vector. Plasmids containing the inserts were sequenced. It was found that two variants of IGS, 75- and 120-bp-long, respectively, are present in the 5S rDNA of T. batis, and the level of similarity between them amounts to 32% only. Therefore, T. batis possess the smallest size of the 5S rDNA IGS among all lepidopterans studied to date. Within the IGS, several variants of microsatellite sequences were found. In the long variant of the IGS in the position -22 bp a TATA-like motif was identified, which may be involved in transcription initiation, whereas in the short variant of the IGS this motif was lost due to deletion.

EFFECT OF SUCROSE ON EXPRESSION OF APX GENES UPON HEAT STRESSAim. Sucrose plays an important role as a signaling molecule that causes changes in gene expression. However, the effect of sucrose on gene expression of antioxidant enzymes is poorly understood. The purpose of our study was to investigate the effect of sucrose on the expression of the multigenic family Apx in Arabidopsis thaliana under heat stress conditions Methods. Leaves of A. thaliana were exposed to heat stress at 37ºC in the presence or in absent of sucrose. Subsequently, mRNA levels were determined in using quantitative RT-PCR. Results. It was found that absence of sucrose in the incubation buffer resulted in a decrease of mRNA for most Apx genes, both in heat stress-treated samples and after incubation at room temperature. The strongest effect was shown for Apx2: without sucrose the level of mRNA under heat stress was 30 times lower. Conclusions. Obtained data showed that sucrose can perform a signaling role in regulating the stress response upon heat stress, and, in particular, enhance the temperature-dependent gene expression of Apx1 and Apx2.

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