Bižienė, Renata

The study analysed single nucleotide polymorphisms (SNP) of the growth hormone (GH) (GH1-exon 5, 2141C>G, GH2-exon 5, 2291A>C, GH3-intron 3, 1548C>T) and signal transducer and activator of transcription 5A (STAT5A) (exon 7, 6853C>T) in three beef cattle breeds (Angus, Charolais, and Limousin; n = 124), and their association with productivity traits. Significant associations were identified between the GH1 (2141C>G) polymorphism and traits like daily weight gain and carcass weight, with the CC genotype showing the most favourable effect. The AA genotype of the GH2 (2291A>C) polymorphism and the CC genotype of the GH3 (1548C>T) polymorphism were the most common and were associated with higher weight gain and improved carcass characteristics. For the STAT5 gene, the CC genotype also demonstrated a significant positive association with productivity traits. These findings highlight the potential utility of these polymorphisms as genetic markers for beef cattle selection. This study is the first to report on the frequency of these alleles and their associations with productivity traits in beef cattle raised in Lithuania.

Viral infections are a major factor contributing to honey bee (Apis mellifera) colony losses worldwide. Genetic variation among individual bees may influence susceptibility to infection, thereby affecting colony-level resilience. This study investigated the relationship between host genotype and total virus infection intensity in honey bees. A total of 140 adult workers were collected from four regions in Lithuania and genotyped at SNP9– 9224292 (AA, AG, GG). Viral presence was assessed using PCR targeting three common honey bee viruses—Black queen cell virus (BQCV), Chronic bee paralysis virus (CBPV), and Deformed wing virus (DWV)—and total virus infection intensity per bee was calculated as the number of detected viruses (ranging from 0 to 3). Non-parametric Kruskal–Wallis tests were used to compare infection intensities among genotypes, and Spearman’s rank correlation examined the association between G allele count and infection intensity. Bees with AA and AG genotypes exhibited higher median infection intensities (interquartile range [IQR] 1–2) than GG bees (IQR 0–1). AA bees showed the widest distribution (0–3), whereas AG and GG bees displayed narrower ranges (0–1 and 0–2, respectively). The Kruskal–Wallis test revealed significant genotype-dependent differences (H = 57.296, df = 2, p < 0.001). A moderate negative correlation was observed between G allele number and infection intensity (ρ = –0.576, p < 0.001), indicating that bees carrying more G alleles tend to harbor fewer viral infections. These results suggest that variation at SNP9–9224292 is associated with differences in overall virus infection intensity, with the GG genotype showing lower susceptibility. The findings highlight the role of host genetics in shaping viral infection dynamics and support further exploration of genetic factors that may enhance colony health and resistance.

Honeybee (Apis mellifera) colonies are threatened by multiple viruses, and while seasonal dynamics and environmental conditions strongly influence their prevalence, knowledge of these patterns remains incomplete [1]. Honeybee colonies harbour multiple viruses with diverse transmission routes: some are closely linked to Varroa destructor infestation, while others are transmitted primarily via direct contact between bees and through ingestion of virus-contaminated food resources [2]. Understanding the drivers of these patterns is essential for effective disease management. We investigated the seasonal prevalence of four honeybee viruses — acute bee paralysis virus (ABPV), black queen cell virus (BQCV), chronic bee paralysis virus (CBPV), and deformed wing virus (DWV) — in colonies across nine regions of Lithuania during the 2024 beekeeping season. In total, 97 honeybee samples were collected from nine regions of Lithuania (Kaunas, Kupiškis, Panevėžys, Pasvalys, Raseiniai, Šakiai, Šiauliai, Tauragė, and Ukmergė) during spring, summer, and fall of 2024, and screened by PCR for target viruses. Israeli acute paralysis virus (IAPV), sacbrood virus (SBV), and Kashmir bee virus (KBV) were also tested but not detected. Two distinct seasonal profiles emerged. ABPV and BQCV prevalence was highest in spring (41.9% and 87.1%, respectively) and summer (35.5% and 80.6%) and sharply reduced in fall (2.9% and 34.3%), while CBPV and DWV showed the opposite pattern, with low spring levels (6.5% each) and peaks in autumn (31.4% and 77.1%). These findings suggest that different viruses are influenced by distinct epidemiological drivers, with ABPV and BQCV more closely associated with early-season colony conditions, and CBPV and DWV linked to late-season factors, such as Varroa dynamics. Understanding these seasonal patterns is critical for improving honeybee health management and mitigating the impact of viral infections on colonies.

In recent years, dogs have become an integral part of human life and are among the most common companion animals. However, undesirable behaviour can negatively affect both animal welfare and owner quality of life [1]. Aggression in dogs, while a normal communicative behaviour, is frequent and generally considered undesirable [2]. Understanding its genetic background is, therefore, important for animal welfare and human safety. The aim of this study was to investigate polymorphism of the dopamine receptor D4 gene (DRD4) gene, located in the second intron, which has been associated with unpredictable or spontaneous behaviour and aggressive tendencies in dogs of various breeds. The DRD4 gene encodes the D4 receptor and is expressed in the limbic system regions responsible for cognition and emotion [3]. A variable number tandem repeat (VNTR) polymorphism consisting of a 17 bp insertion/deletion has been identified in the second intron. A 2013 study reported two alleles: P (194 bp) and Q (211 bp), with the P/P genotype linked to aggression [4]. In this study, 94 dogs from 35 breeds were examined. Based on an owner questionnaire, dogs were categorised as aggressive or non-aggressive, hyperactive or non-hyperactive, and exhibiting or not exhibiting spontaneous behaviour. DNA was extracted from oral epithelial cells using a Chelex solution, and genotypes were determined by PCR. Among aggressive dogs (n = 16), 62.5% carried the P/P genotype compared with 57.7% of non-aggressive dogs (n = 78). The Q/Q genotype was found in 12.5% and 19.2% of these groups, respectively. P/P was the most frequent, and Q/Q was the least frequent genotype. Comparison of the genotyping results with the owners’ survey data revealed no statistically significant associations between the DRD4 gene polymorphism and the expression of aggressive or spontaneous behaviour. Similarly, no association was found between the polymorphism and hyperactivity

The aim of the study to evaluate relationship between breed, GH and CAST genotypes, and FA composition in the ovine intramuscular fat of musculus Semimembranosus. To fulfil this aim, 175 blood samples were drawn by jugular vein puncture from Lithuanian Black-Headed (N43), Lithuanian Black-Headed *Ile de France (N43), Lithuanian Black-Headed *Suffolk (N44), and Lithuanian Black-Headed *Texel (N45) lambs. The lambs were weighed weekly, and the growth rate was calculated using birth weight and month weight values. Genomic DNA was extracted from blood samples taken into EDTA containing tubes, using a “GeneJET Genomic DNA Purification Kit” (Thermo Scientific, Waltham, MA, USA). The method of polymerase chain reaction and restriction length polymorphism were used to genotype growth hormone (GH) and (CAST) gene polymorphisms. Meat samples of four lamb breeds were taken for analysis (200–250 g from musculus Semimembranosus were taken 48 h after carcass meat cooling). The fatty acid methyl esters (FAMEs) were analyzed using a gas chromatography mass spectrometry (GC/MS) instrumental technique. All data were evaluated statistically. Studies have shown that purebred Lithuanian Black-Headed lambs are born with a higher weight, so it is not advisable to mix them with Ile de France, Suffolk, or Texel breeds. Also, our research shows that the most beneficial breed are lambs that have the BB genotype of the GH gene and the MN genotype of the CAST gene, as these lambs are born with the greatest weight and gain. The meat of Lithuanian Black-Headed lambs showed the lowest content of SFA and the largest content of PUFA. The ratio ω-6/ω-3 FA varied from 2.71 (Lithuanian Black-Headed * Suffolk) to 4.52 (Lithuanian Black-Headed). Based on the research, it can be concluded that the purebred Lithuanian Black-Headed lambs had higher birth weight, therefore it is not appropriate to mix them with Ile de France, Suffolk, or Texel breeds.

Background and Aim: Cholesterol deficiency (CD) in Holstein cattle, caused by a loss-of-function mutation in the apolipoprotein B (APOB) gene, is a heritable autosomal recessive condition with known implications for fat metabolism and cholesterol transport. This study aimed to investigate the effect of the CD genotype on milk yield components, cholesterol concentration, and somatic cell count (SCC) in Lithuanian Holstein cows, and to determine whether lactation number modulates these relationships.

Materials and Methods: A total of 188 cows were classified by lactation: 1st (n = 44), 2nd (n = 50), 3rd and 4th (n = 60), and ≥5th (n = 34). Genotyping for the APOB mutation was conducted using allele-specific polymerase chain reaction. Milk fat, protein, lactose, and SCC were determined using LactoScope Fourier-transform infrared spectroscopy and Somascope methods, while cholesterol concentration was measured by high-performance liquid chromatography. Statistical analysis involved the Kruskal–Wallis H test due to non-normal data distribution.

Results: The heterozygous CD genotype was identified in 17.02% of the population, with wild-type and mutant allele frequencies of 0.91 and 0.09, respectively. Non-carriers showed marginally higher fat, protein, and cholesterol levels, with a statistically significant difference in fat content (p = 0.04). When stratified by lactation, significant differences were observed for fat content in the 1st lactation group (p = 0.026), SCC in the 2nd (p = 0.038), and protein content in the 3rd (p = 0.030). No significant variation in milk cholesterol concentration was detected across genotype groups in any lactation group.

Conclusion: This study confirms the presence of the CD-associated APOB allele in the Lithuanian Holstein population. While CD status significantly influenced milk fat percentage, its effect on other milk composition traits and SCC was limited. Parity exhibited specific but non-consistent modulating effects. Further large-scale, longitudinal studies are warranted to elucidate the physiological underpinnings of these findings.

The aim of this study was to investigate the prevalence of polymorphisms of STAT5 and GH genes and to determine their influence on the productivity traits in beef cattle. A total of 95 animals were genotyped, belonging to the breeds Angus, Limousin, Galloway and Simmental. Polymorphisms of STAT5 and GH locus were identified using a PCR-RFLP method. The evaluation of the STAT5 gene polymorphism (7 exon, 6853C> T) demonstrated that C allele (frequency 0.959) and CC genotype (frequency 0.918) were the most common in beef bull populations reared in Lithuania. This polymorphism had a statistically significant effect on the live weight index of animals. The examination of the GH gene polymorphism (5 exon, 2141C> G) revealed that the G gene allele (frequency 0.612) and heterozygous CG genotype (frequency 0.424) were the most common. This polymorphism had a statistically significant effect on daily bull weight and live weight. Bulls of the homozygous CC genotype exhibited better economic characteristics. In conclusion, our results demonstrated the potential of polymorphisms of GH and STAT5 genes as candidates for the investigation of quantitative traits in cattle.

Growth hormone (GH) gene acts and mediates the growth of bones and muscles. It is known that GH is the main regulator of postnatal somatic growth, stimulating anabolic processes, and skeletal growth [1, 2]. The growth hormone (GH) gene is a candidate gene for predicting growth and meat quality traits in animal genetic improvement since it plays a fundamental role in growth regulation and development [3, 4]. The aim of this study was to investigate the prevalence of GH gene (2141C>G) polymorphism and to determine its influence on the carcass quality in beef cattle. Samples of cattle hair follicles were collected from 85 bulls of Angus (41), Limousin (19), Galloway (19) and Simmental (6) cattle. The bulls were raised under the same conditions in Šilutė control bulls feeding station. The hair samples and slaughter data (the ratio of muscle development distributed according to the EUROP system) were obtained from private slaughterhouses, where animals were slaughtered. Bovine genomic DNA was extracted from hair follicles using the Chelex DNA extraction method. Polymorphism of the GH locus was identified using a PCR-RFLP method (AluI restriction endonuclease). Investigation of polymorphism 2141C>G of the GH gene showed that the C allele of the GH gene was the most frequent compared with the G allele in the general population of beef cattle. The CG genotype of the GH gene was the most frequent in the studied population (43%) followed by the CC genotype (40%) while the GG genotype had the lowest frequency (17%). After evaluation of the observed and expected heterozygosity across the investigated group of animals, the observed heterozygosity was found lower than expected, indicating the lack of genetic diversity of the studied loci, although the difference was not statistically significant. According to the EUROP carcass classification system, most of the GG genotypes bovine carcasses were classified as the O (fair) carcass conformation class and the 3rd (average) fat coverage class; most of the CG genotype bovine carcasses were classified as the R (good) carcass conformation class and the 3rd (average) fat coverage class; and most of the CC genotype bovine carcasses were classified as U (very good) and R (good) carcass conformation classes and the 3rd (average) fat coverage class. The results were statistically significant (P value – 0.010, P < 0.05). In conclusion, the results showed that the GH gene polymorphism (2141C>G) affected carcass conformation and fat coverage in beef cattle.

Objective: Diabetes mellitus (DM) is a prevalent endocrine condition found in cats. Recent research has identified a connection between a higher risk of diabetes in cats and genetic factors. This genetic susceptibility to type 2 diabetes is associated with genes that control insulin secretion and function, as well as those that impact factors like obesity. The purpose of the study was to determine the prevalence of the melanocortin 4 receptor (MC4R) gene missense mutation among cats and to investigate the relationship between body condition score (BCS) and the occurrence of diabetes in felines. Materials and Methods: Genotype analysis was done for 45 samples. The research results were obtained with the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. The 1,200-bp PCR product was cut with BstOI restriction enzyme. Results: Upon analyzing the data, it was found that 37.8% (n = 17) of the subjects carried the MC4R gene mutation. Across the entire population of cats studied, the C allele associated with the mutation was most prevalent in the group of cats with DM (frequency of 0.3) and least common among the clinically healthy cats (frequency of 0.2). Conclusion: After analysis of the study results, a statistically significant difference was observed between cats with DM and clinically healthy cats in the comparison of their BCS (p < 0.05). The association of the MC4R gene polymorphism with overweight and the development of diabetes has been identified.

The Varroa destructor mite is a widespread major pest of honey bees Apis mellifera. The rapid spread of Varroa mites among bee colonies may be due to several factors, including drifting of infested bees, movement of bee swarms, robbing of weakened colonies. However, some bees’ colonies are resistant to V. destructor and that may be related to changes in the amino acid sequence of the Mblk1 protein leading to higher brain functions in bees. In this study, we aimed to test the contribution of three Mblk-1 gene polymorphisms to the resistance to V. destructor mites. This case–control study involved 117 DNA samples that were genotyped for three single nucleotide polymorphisms (SNP) using the real-time polymerase chain reaction method. Statistical analysis was performed with SPSS Statistics 20 and PLINK software. SNP at position 7454459 (Asn → Thr) of Mblk-1 gene mutant allele A was more common in untreated domestic and wild honey bees (18.90% and 8.14% respectively; p=0.001) compared to treated domestic bees which persistently infected with the disease. Regression analysis showed that recessive AA genotype of this polymorphism significantly reduced the odds for varroosis (odds ratio=0.166, 95% confidence interval = 0,049-0,562, p=0.004). SNP at position 7454459 (Asn → Thr) of the Mblk-1 gene has a prominent interface with resistance to varroosis.