The objective of the present study was to evaluate the influence of the genotypes of two single nucleotide polymorphisms (SNPs) – c.78C>T located in the growth hormone gene (GH) and c.106C>G in the growth hormone receptor gene (GHR) on individual body weight (IBW) during the growing period at 35, 70 and 90 d of age on a total of 107 weaned Californian breed rabbits. The restriction fragments obtained revealed that 74.8% of the rabbits carrying c.78C>T SNP and 52.3% of the rabbits carrying c.106C>G SNP were heterozygous, which indicated a moderate level of genetic diversity in this Californian population. Association analysis based on a single-gene approach revealed that c.78C>T polymorphism in the GH gene had a significant effect (PT TT genotype, and detected individuals were significantly affected by the dominance effect. Significant differences were observed between individuals with homozygous c.106C>G CC genotype and those with heterozygous CG genotype. The highest IBW (2462.0±198.3 g) was observed in rabbits carrying the c.106C>G CC genotype and detected individuals were significantly affected by the additive effect. A total of nine combined genotypes of c.78C>T and c.106C>G SNPs was found in the study, of which only four major groups (CT/CC, CC/CG, CT/CG, and CT/GG) were concerned in the diplotype analysis. Significant differences were observed between individuals with CT/CC and CC/CG genotype combinations, and between those with the CC/CG and CT/GG diplotypes. However, the highest IBW at 90 d of age (2447.2±213.8 g) was observed in rabbits carrying the CT/CC genotype combinations. The highest coefficient of determination found for individual body weight at 90 d of age (R2=10.8%) indicated a high effect of genotype combinations. In conclusion, the results obtained suggested that c.78C>T of GH gene and c.106C>G of GHR gene could be useful candidate genes to improve growth performance in Californian rabbits with potential application in rabbit breeding programmes.

Taking into consideration that the growth hormone (GH) gene in rabbits is a candidate for meat production, understanding the genetic diversity and variation in this locus is of particular relevance. The present study comprised 86 rabbits (Oryctolagus cuniculus) divided into 3 groups: New Zealand White (NZW) outbred rabbits; first-generation inbred rabbits (F1) and second-generation inbred rabbits (F2). They were analysed by polymerase chain reaction-based restriction fragment length polymorphism method. A 231 bp fragment of the polymorphic site of the GH gene was digested with Bsh1236 restriction enzyme. Single nucleotide polymorphisms for the studied GH locus corresponding to 3 genotypes were detected in the studied rabbit populations: CC, CT and TT. In the synthetic inbred F1 and F2 populations, the frequency of the heterozygous genotype CT was 0.696 and 0.609, respectively, while for the homozygous CC genotype the frequency was lower (0.043 and 0.000), and respective values for the homozygous TT genotype were 0.261 and 0.391. This presumed a preponderance of the T allele (0.609 and 0.696) over the C allele (0.391 and 0.304) in these groups. In outbred rabbits, the allele frequencies were 0.613 (allele C) and 0.387 (allele Т); consequently, the frequency of the homozygous CC genotype was higher than that of the homozygous TT genotype (0.300 vs. 0.075). Observed heterozygosity for the GH gene was higher than expected, and the result was therefore a negative inbreeding coefficient (Fis=–0.317 for outbred NZW rabbits; –0.460 for inbred F1 and –0.438 for inbred F2), indicating a sufficient number of heterozygous forms in all studied groups of rabbits. The application of narrow inbreeding by breeding full sibs in the synthetic population did not cause a rapid increase in homozygosity.

Background: Enterococci are intrinsically resistant/tolerant to various antimicrobial agents and can also acquire and combine different mechanisms of resistance, including quorum-sensing regulation, to most active compounds, which makes enterococcal infection treatment even more challenging. The aim of this study was to evaluate the pattern of antimicrobial resistance and to analyze the frequency of quorum-sensing asa1 and esp genes in clinical isolates representing the genus Enterococcus. Methods: Multiplex PCR assays were performed for the identification of 110 enterococcal isolates and the determination of their antibiotic susceptibility and the presence of asa1/esp genes. Additionally, the antibiotic resistance of the isolates was tested by the Kirby–Bauer disk diffusion method. Results: 90% of the isolates were identified as Enterococcus faecalis and 10% as Enterococcus faecium. Quorum-sensing regulation genes were present in 109 isolates. Aminoglycoside (aac(6′)/aph(2″)-, quinolone (emeA)-, β-lactams (TEM)-, and vancomycin (vanA)-resistance genes were detected in 108 isolates. All of the isolates tested were vanB negative. According to the Kirby–Bauer method, 39% of the isolates expressed multidrug resistance (MDR) and 33% of the MDR E. faecium were vancomycin-resistant. Conclusion: The large percentage of MDR enterococci possessing asa1/esp genes indicated a possible connection between quorum-sensing regulation and drug resistance. Therefore, the regular monitoring of the antimicrobial resistance of Enterococcus spp., and the identification of virulence factors are needed. It is also important to prevent host colonization through the elimination of factors leading to the expression of quorum-sensing genes.

Fusarium spp. represent a critical threat to maize production and food safety due to their mycotoxin production. This study introduces a refined molecular identification protocol integrating four genomic regions—ITS1, IGS, TEF-1α, and β-TUB—for robust species differentiation of Fusarium spp. isolates from post-harvest maize in Bulgaria. The protocol enhances species resolution, especially for closely related taxa within the Fusarium fujikuroi species complex (FFSC). A newly optimized multiplex PCR strategy was developed using three primer sets, each designed to co-amplify a specific pair of toxigenic genes: fum6/fum8, tri5/tri6, and tri5/zea2. Although all five genes were analyzed, they were detected through separate two-target reactions, not in a single multiplex tube. Among 17 identified isolates, F. proliferatum (52.9%) dominated, followed by F. verticillioides, F. oxysporum, F. fujikuroi, and F. subglutinans. All isolates harbored at least one toxin biosynthesis gene, with 18% co-harboring genes for both fumonisins and zearalenone. This dual-protocol approach enhances diagnostic precision and supports targeted mycotoxin risk management strategies.

Five rabbit populations of New Zealand White (NZW), Californian (CAL), crossbred NZW×GW and two generations of the synthetic population – SPF₁ and SPF₂ reared in Bulgaria were included in the present study with the aim of detecting the genetic variability of the growth hormone encoding gene (GH) via polymerase chain reaction with the restriction fragment length polymorphism analysis and direct sequencing. The targeted region of the rabbit GH gene was amplified and a fragment of a total of 231 bp was obtained in all studied populations. Allele identification was determined after enzymatic digestion, where two fragments of 62 and 169 bp correspond to allele C and an undigested fragment of 231 bp corresponds to allele T. Two additional bands of 107 and 124 bp evidenced A/G genetic polymorphism in the rabbit GH gene. Thirtyeight percent of the studied rabbits were carriers of the double mutation (C/T+A/G) in the same locus as the studied GH gene. The sequence analysis revealed two nucleotide substitutions – g.111C>T and g.156A>G in the non-coding region between the regulatory TATA box and 5’ UTR region, and a novel g.255G>A genetic variant in intron 1 of GH gene. The A>G transition was most frequent (40.57%), compared to the other ones, G>A (28.57%) and C>T (10.80%), respectively. The most frequent genotype in the NZW population was homozygous TT (0.93), with a prevalence of the T allele (0.97) over allele C (0.03) for g.111C>T SNP site. The distribution of the allele and genotype frequencies at the sites g.156A>G and g.255G>A in this rabbit group was identical, with the highest value of 0.93 for alleles A and G, respectively. The rabbit populations CAL and NZW×GW showed equal frequencies of the prevalent T allele (0.83) and for homozygous TT genotype (0.67) according to g.111C>T SNP. The highest values were obtained for the allele А (0.83) and for homozygous AA genotype (0.67) at c.33A>G SNP in these rabbit groups. The highest values (0.67, 0.60 and 0.80) for the heterozygous genotypes at g.111C>T, g.156A>G and g.255G>A SNPs, respectively, were detected among the SPF₂ rabbit population, compared to the both homozygous genotypes. The results obtained in the present research indicates a significant degree of genetic variability of the studied polymorphic GH locus in the SPF₂ rabbit group.

Molecular identification via Internal Transcribed Spacer region (nrDNA-ITS) sequencing of Fusarium spp. isolates from wheat originated from Stara Zagora region, were performed for the first time in Bulgaria. А total of 60 wheat samples (Triticum aestivum) were morphologically identified at the genus level as Fusarium spp. in advance. The rDNA-ITS region of all isolates was successfully amplified and the PCR products obtained were directly sequenced. After a comparison of detected sequences with NCBI database, members of three different fungal genera (Fusarium, Chaetomium, and Alternaria) were identified. Among Fusarium isolates, the F. tricinctum was prevailing, followed by F. poae. A total of three isolate F. proliferatum, F. graminearum and F. equiseti were presented with a single probe. The lowest genetic distance (0.004) was detected between F. tricinctum isolates. On the base of genetic distances, fungal isolates were grouped in two main clusters – one comprising F. tricinctum isolates and F. proliferatum, and second including F. equiseti, F. graminearum and F. poae. It could be concluded that the rDNA-ITS genome region of the genus Fusarium may be used as a suitable marker of early detection, accurate and reliable identification of Fusarium spp. contamination of wheat. The timely and accurate information would assist in the selection of appropriate approaches for control of fusarium infections and possible mycotoxins contamination of agricultural production.