Ivona V Dimitrova | Printnem (original) (raw)

Papers by Ivona V Dimitrova

The Bulgarian Dairy Synthetic Population (BDSP) is the most numerous sheep breed in the country w... more The Bulgarian Dairy Synthetic Population (BDSP) is the most numerous sheep breed in the country with a fertility of about 150%. Fertility in sheep is mainly determined by several major genes known as fecundity genes (Fec), one of which is GDF9 (growth differentiating factor 9). The aim of this study was to analyze the association of the GDF9 gene polymorphism at SNP G1 with litter size depending on age and birth type in BDSP ewes. The analysis included 163 sheep in which a 462 bp fragment of exon 1 of the GDF9 gene was amplified and subsequently cut with the restriction enzyme HhaI. As a result, two alleles were established: the wild-type G (with a frequency of 0.76) and the mutant A (with a frequency of 0.24), as well as the three possible genotypes AA, AG and GG with frequencies of 0.06, 0.35 and 0.59, respectively. There was no statistically significant difference in litter size between different genotypes at SNP G1. Significant differences were found in the litter size of the 2nd lambing (1.52) compared to the 4th lambing ewes (1.77), and in the single-born ewes (1.56) compared to ewes born as twins (1.70) (p ≤ 0.05). Proven higher fertility was observed in ewes born as twins with genotype AA (1.97) compared to twins born as carriers of heterozygous genotype AG (1.65) (p ≤ 0.05).

Biotechnology & Biotechnological Equipment

Teneva, A. & Dimitrova, I. (2021). Application of DNA markers for the assessment and characteriza... more Teneva, A. & Dimitrova, I. (2021). Application of DNA markers for the assessment and characterization of genetic resources in sheep breeding. Bulg. J. Agric. Sci., 27 (6), 1238–1247 This review summarizes the advances in molecular biotechnology for characterization of AnGR in sheep breeding. The review gives a brief summary on the development of genetic markers including both the classical genetic markers and more advanced DNA-based molecular markers – new generations of molecular markers for use in the genetic improvement of sheep breeds. This will help better understanding the characteristics of different genetic markers and the genetic diversity of sheep genetic resources. In this review, we focus on the introduction of the most important DNA-based markers, and their various applications in characterizing sheep animal genetic resources (AnGR).

Ivanova, T., Stoikova-Grigorova, R., Bozhilova-Sakova, M., Ignatova, M., Dimitrova, I. & Koutev, ... more Ivanova, T., Stoikova-Grigorova, R., Bozhilova-Sakova, M., Ignatova, M., Dimitrova, I. & Koutev, V.(2021). Phenotypic and genetic characteristics of fecundity in sheep. A review. Bulg. J. Agri. Sci., 27 (5), 1002–1008 The phenotypic characteristics of animals are result of the complex interaction of a number of genetic and non-genetic factors, which usually act simultaneously and it is difficult to determine the degree of influence of each of them. Early identification of the genetic traits of individuals enables more efficient management of selection. Fertility determins the cost-effectiveness of sheep farming, regardless of productive direction. The individual fertility of the animals is determined by the number of lambs born per sheep. This trait is characterized by a low inheritance rate, hence conventional breeding methods shows slow progress. The introduction of new molecular-based technologies to improve productivity contributes to a greater and faster effect on the realizati...

BIO Web of Conferences, 2022

Karnobat sheep plays an important role in the development of sheep breeding in Southeastern regio... more Karnobat sheep plays an important role in the development of sheep breeding in Southeastern region of Bulgaria. They are valuable source of genetic material. The aim of present experiment was to determine the allele variation of CAST gene in Local Karnobat and Karnobat Merino sheep breeds. A total of 60 blood samples were collected – 30 per breed. DNA was extracted and genotypes of all animals were identified by means of PCR-RFLP technique. The restriction reactions were accomplished by specific enzyme MspI. As expected both breeds were characterized with low level of genetic diversity due to the fact that mostly maintaining selection has been implemented. In Local Karnobat sheep breed was identified only one heterozygous individual from all 30. In Karnobat merino were identified allele M with frequency 0,97 and allele N with frequency 0,03. Genotypes MM and MN were revealed with frequencies 0,93 and 0,07, respectively. According to the statistical analysis both breeds were in HWE e...

The development of cell-mediated immunity in rams was analyzed by the breed-dependent patterns of... more The development of cell-mediated immunity in rams was analyzed by the breed-dependent patterns of the responsiveness of peripheral blood lymphocytes to common mitogens (phytohemagglutinin, PHA; concanavalin A, ConA; poke-weed mitogen, PWM), in a mixed lymphocyte culture (MLC), in order to establish the basic immune parameters in clinically normal rams. Investigations were carried out on 26 rams from the breeds Karakachan and Copper-Red Shoumen. It was established that there are close differences between prosliferative activity of lymphocytes of the two groups of animals. The immune parameters obtained for the two local sheep breeds may serve as a basis for further research on lamb systemic immune responsiveness regarding differences among breeds.

Доклади на Българската академия на науките Comptes rendus de l'Académie bulgare des Sciences

This experiment was conducted in order to be identified the allelic and genotypic polymorphisms o... more This experiment was conducted in order to be identified the allelic and genotypic polymorphisms of FABP3 (heart-type fatty acid binding protein) gene in 30 ewes from Bulgarian Dairy Synthetic Population breed reared in Experimental base-Tzarev Brod-part of the Agricultural Institute-Shumen. FABP3 gene is a candidate marker that influences milk fat content and marbling of meat. Thirty blood samples were collected from v. jugularis in vacuum tubes with EDTA. Genomic DNA was extracted manually with commercial kit. By means of PCR-RFLP technique with endonuclease BseDI in exon 2 of FABP3 gene (SNP3) were determined the allele and genotype variants of the investigated animals. In this population were observed two alleles-wild allele A with frequency 0.15 and mutant allele G-with 0.85. Two different genotypes were identified-homozygous GG with frequency 0.67 and heterozygous genotype AG with frequency 0.33. Ho (observed heterozygosity) was 0.330 and He (expected heterozygosity) was 0.255. This herd was found to be in Hardy-Weinberg equilibrium (p>0.05).

Karnobat sheep plays an important role in the development of sheep breeding in Southeastern regio... more Karnobat sheep plays an important role in the development of sheep breeding in Southeastern region of Bulgaria. They are valuable source of genetic material. The aim of present experiment was to determine the allele variation of CAST gene in Local Karnobat and Karnobat Merino sheep breeds. A total of 60 blood samples were collected-30 per breed. DNA was extracted and genotypes of all animals were identified by means of PCR-RFLP technique. The restriction reactions were accomplished by specific enzyme MspI. As expected both breeds were characterized with low level of genetic diversity due to the fact that mostly maintaining selection has been implemented. In Local Karnobat sheep breed was identified only one heterozygous individual from all 30. In Karnobat merino were identified allele M with frequency 0,97 and allele N with frequency 0,03. Genotypes MM and MN were revealed with frequencies 0,93 and 0,07, respectively. According to the statistical analysis both breeds were in HWE equilibrium.

Доклади на Българската академия на науките Comptes rendus de l'Académie bulgare des Sciences

A mutation in the ovine ABCG2 gene could influence the fat content and milk yield in sheep. The a... more A mutation in the ovine ABCG2 gene could influence the fat content and milk yield in sheep. The aim of this study was to identify a 35-bp deletion/insertion in intron 5 of the ABCG2 gene in two herds of the Bulgarian Dairy Synthetic Population (BDSP) breed. The first population was raised in the Agricultural Institute in Shumen and included 116 ewes. The second one was bred at the Institute of Animal Science-Kostinbrod and included 68 ewes. Genomic DNA was extracted from a total of 184 blood samples. The allelic variants were determined by polymerase chain reaction (PCR) amplification with a specific primer set. The results revealed the presence of the wild-type allele "+" with a frequency of 0.53 and the mutant allele "-" with a frequency of 0.47 in BDSP-Shumen. In the animals from BDSP-Kostinbrod, the wild-type allele "+" had a frequency of 0.71 and the mutant allele "-", a frequency of 0.29. All three possible genotypes were identified in both herds. In BDSP ewes-Shumen, the wild-type genotype "+/+" had a frequency of 0.22; the heterozygous genotype, a frequency of 0.63; and the mutant genotype "-/-", a frequency of 0.15. In BDSP-Kostinbrod, the wild-type genotype "+/+" had a frequency of 0.55, the heterozygous genotype "+/-", 0.32; and the mutant genotype "-/-", 0.13. Both tested herds were not consistent with the Hardy-Weinberg equilibrium (HWE). In BDSP-Shumen p = 0.01 and in BDSP-Kostinbrod p = 0.05.

Milk is a product with highly dynamic characteristics. Its composition varies according to the br... more Milk is a product with highly dynamic characteristics. Its composition varies according to the breed, lactation period, nutrition, health status of the animal, as well as the conditions of milking and storage. Investigation of genetic potential and productive traits of farm animals is essential for every producer. The phenotypic characteristics of sheep are the result of the complex interaction of a wide range of genetic and non-genetic factors. They are slightly influenced by traditional selection. Therefore, it is essential to study the genetic pattern of inheritance of these traits. In the last decades of the 20 th century, several researchers have studied genetic variation in populations of different breeds of farm animals, using genetic markers of class I, such as blood types and polymorphisms of proteins in blood and milk. Modern methods of molecular biology make it possible to use class II genetic markers in research to identify genetic polymorphisms in the loci of molecular markers and associate them to certain phenotype characteristics, study the laws of organization and functioning of the genome, decipher the mechanisms for the realization of genetic information. The obtained data from these analyzes are successfully applied in the development of breeding programs in animal husbandry practice, to speed up the realization of genetic progress. Some of the main major candidate genes that have been studied related to milk productivity in sheep are: prolactin, αs1, αs2, β and κ-casein, α-and β-lactoglobulin, PIT-1.

In the present study was investigated the single nucleotide polymorphism in exon II of the melato... more In the present study was investigated the single nucleotide polymorphism in exon II of the melatonin receptor (MTNR1A) gene in a total of 90 individuals representing three fine fleece sheep breeds: Caucasian Merino, Ascanian Merino and Karnobat Merino. By means of PCR-RFLP analysis two allele variants of MTNR1A gene (C and T) and three genotypes (CC, CT and TT) have been identified. The obtained genotype frequencies of alleles C and T in the investigated sheep breeds were: 0.60 and 0.40 in Caucasian Merino sheep, 0.47 and 0.53 in Askanian Merino sheep, 0.60 and 0.40 in Karnobat Merino sheep, respectively. The genetic diversity at MTNR1A gene was with the highest value in the population of Ascanian Merino (H o = 0.533 и H e = 0.498). The lowest coefficient of inbreeding (F is =-0.070) was also observed in this group and it was in correspondence with HWE equilibrium (p = 0.4). The frequency of mutant allele T was higher (0.53) than the wild allele C (0.47). In Caucasian and Karnobat Merino breeds the allele frequencies were the same-0.60 and 0.40 for allele C and allele T, respectively. Despite the same allelic frequencies, the two breeds had different distributions in the genotype frequencies, with the most significant difference in the heterozygous genotype CT-0.40 for Caucasian Merino and 0.27 for Karnobat Merino. The population of Karnobat Merino sheep breed was not consistent with HWE with p = 0.02. The results in this study showed polymorphism in exon II of the ovine MTNR1A gene in all tested breeds. Due to that fact, it could be concluded that this gene is suitable for genetic marker.

The success of sheep production depends largely on two important characteristics of sheep-their g... more The success of sheep production depends largely on two important characteristics of sheep-their growth ability and meat quality. The myostatin gene (MSTN) is one of the major regulators of skeletal muscle growth and development and it is defined as a suitable candidate gene for genetic improvement through marker-assisted selection. In this study by means of PCR-RFLP method was identified allelic variants of intron 1 of MSTN gene in ten Bulgarian sheep breeds-Askanian (30 animals), Caucasian (30 animals), Karnobat Merino (60), Local Karnobat (30), Karakachan (60), Breznik (30), Cooper-Red Shoumen (30), Il de France (60), Bulgarian Dairy Synthetic Population (60) and Pleven Black headed (30). Genomic DNA was extracted from 420 blood samples. After PCR amplification, the received 497 bp fragment of the myostatin gene was digested with the restriction enzyme DraI. The results showed that this area of the myostatin gene is highly conservative in Bulgarian sheep breeds. All of the investigated ten sheep breeds were monomorphic for the tested locus. Only the B allele and genotype BB were found in all studied animals.

Rabbit breeding is a branch of animal husbandry, that provides high-quality and dieted meat. In B... more Rabbit breeding is a branch of animal husbandry, that provides high-quality and dieted meat. In Bulgaria, this sector is slightly developed, regardless of the growing interest in it. Rabbits have excellent biological abilities-early maturity, high growth intensity, high fertility, and good feed absorption. Rabbit meat has excellent taste qualities, low cholesterol content, and a low percentage of bones in the carcass. In Bulgaria, rabbits are raised mainly for meat. Although the industry is well developed, rabbit meat production is in demand on the market due to its dietary properties, such as low fat and high protein content. Most of the rabbit population in Bulgaria has consisted of White New Zealand and California breeds, but the breeds White Giant, Belgian Giant, Chinchilla, the newly created breed group-Veselina, and the hybrid ZIKA are also bred but in smaller populations and mainly in private farms. The rabbit genome consists of 44 chromosomes (2n = 44). The identification of genome regions and genes related to important phenotypic traits allows the selection of the genetic markers linked with the trait of interest. Marker-assisted selection (MAS) contributes to choosing animals at the early stage of breeding by improving and increasing the expected results compared to the standard methods of selection.

The phenotypic characteristics of animals are result of the complex interaction of a number of ge... more The phenotypic characteristics of animals are result of the complex interaction of a number of genetic and non-genetic factors, which usually act simultaneously and it is difficult to determine the degree of influence of each of them. Early identification of the genetic traits of individuals enables more efficient management of selection. Fertility determins the cost-effectiveness of sheep farming, regardless of productive direction. The individual fertility of the animals is determined by the number of lambs born per sheep. This trait is characterized by a low inheritance rate, hence conventional breeding methods shows slow progress. The introduction of new molecular-based technologies to improve productivity contributes to a greater and faster effect on the realization of animal genetic resources. The assessment of the breeding value of animals at the earliest possible age makes it possible to maximize the effect of the selection and to increase the use of animals with the highest genetic potential. The molecular markers and the application of RFLP-PCR method allow the determination of allelic variants of genes related to the quantity and quality of animal productivity. By identifying the different polymorphic variations and their phenotypic manifestation, a database can be accumulated to manage the genetic progression of economically important traits. Many mutations have been found in sheep that affect fertility and ovulation rates to varying degrees. Large number of mutations which affects ovulation have been found in genes expressing different proteins, such as the BMPR1B or FecB (Booroola gene or the bone morphogenetic protein receptor type 1B), GDF9 or FecG (the growth differentiation factor 9b) and BMP15 or FecX (a bone morphogenetic protein 15).

Целта на проучването е да се установи влиянието на типа на осеменяване на пчелната майка (изкуств... more Целта на проучването е да се установи влиянието на типа на осеменяване на пчелната майка (изкуствено или естествено) върху яйценосната ѝ дейност. Експериментът е проведен през 2021 г. на три пчелина (№ 5063-004 и 5063-0018, намиращи се в с. Буковец, и пчелин № 5185-0506 в с. Раданово), отдалечени един от друг на повече от 5 km в област Велико Търново. В експеримента от всеки пчелин участват две линии пчелни майки-Линия 1 (LM-20) и Линия 2 (LM-45). От всяка линия са сформирани по две групи пчелни семейства. Всяка група се състои от 6 пчелни семейства с инструментално осеменени пчелни майки и 6 пчелни семейства с естествено оплодени пчелни майки. Пчелните майки от групата на инструментално осеменените пчелни семейства са осеменени еднократно със 10 µl семенна течност на възраст 8 дни от своето излюпване. Инструментално осеменените пчелни майки показват по-високи стойности на показателя яйценосна дейност през отделните сезони (пролет и есен) в сравнение с естествено оплодените пчелни майки. Разликите са статистически достоверни (p < 0,001). Установена е статистически достоверна разлика (p < 0,001) между двете линии пчелни майки LM-20, LM-45. Ключови думи: яйценосна дейност на пчелната майка, количество запечатано пило, медоносна пчела (Apis mellifera mellifera L.), инструментално и естествено оплодени пчели майки, яйценосна дейност

The overview includes an analysis of the state, trends, and prospects of beekeeping. The article ... more The overview includes an analysis of the state, trends, and prospects of beekeeping. The article traces the development of the sector in our country and in the European Union over the last 10 years. The number of bee families, the number of beekeeping farms and the amount of honey produced by them are reflected. And also, number of bee families in farms with different number of hives. The data from the Department of Agri-statistics of the Ministry of Agriculture and Eurostat for a period of ten years are summarized. The purpose of the study was to summarize and analyze data over a period of ten years. During the period (2012-2021), an increase in the number of bee colonies and honey production and a significant decrease in bee colonies in our country have beenwere observed. Within the borders of the European Union, losses of bee colonies have been observed in the last two years.

Bone morphogenetic protein 15 (BMP15/FecX) gene is one of the candidate genes for the reproductio... more Bone morphogenetic protein 15 (BMP15/FecX) gene is one of the candidate genes for the reproduction in farm animals, especially sheep. The present study aimed to detect the genetic polymorphism in three different regions of BMP15 gene in sheep from the Bulgarian Dairy Synthetic Population (BDSP) using PCR-RFLP technique. For the purpose of the experiment were used 163 ewes from the herd of the Agricultural Institute-Shumen with records of the number of lambs born from a minimum of two consecutive lambing. The average number lambing of ewe is 4.07. DNA was extracted from blood samples of all ewes, subjected to PCR amplification. The PCR products of 141 bp (FecX G), 153 bp (FecX B), and 240 bp (FecX H) were cut with HinƒI, DdeI, and SpeI restriction enzymes, respectively. In FecX G region were visualized two fragments with length 112 bp and 29 bp (wild genotype ++) in all tested ewes. For FecX B in all animals were obtained two fragments of 122 bp and 31 bp which corresponded to homozygous wild genotype AA. For FecX H all animals were homozygous with CC genotype and only one determined fragment of 240 bp. In conclusion, the findings in present study did not detect any polymorphisms in BMP-15 gene in sheep, regardless their good prolificacy.

Biotechnology & Biotechnological Equipment

BIO Web of Conferences, 2022

Доклади на Българската академия на науките Comptes rendus de l'Académie bulgare des Sciences

Karnobat sheep plays an important role in the development of sheep breeding in Southeastern regio... more Karnobat sheep plays an important role in the development of sheep breeding in Southeastern region of Bulgaria. They are valuable source of genetic material. The aim of present experiment was to determine the allele variation of CAST gene in Local Karnobat and Karnobat Merino sheep breeds. A total of 60 blood samples were collected-30 per breed. DNA was extracted and genotypes of all animals were identified by means of PCR-RFLP technique. The restriction reactions were accomplished by specific enzyme MspI. As expected both breeds were characterized with low level of genetic diversity due to the fact that mostly maintaining selection has been implemented. In Local Karnobat sheep breed was identified only one heterozygous individual from all 30. In Karnobat merino were identified allele M with frequency 0,97 and allele N with frequency 0,03. Genotypes MM and MN were revealed with frequencies 0,93 and 0,07, respectively. According to the statistical analysis both breeds were in HWE equilibrium.

Доклади на Българската академия на науките Comptes rendus de l'Académie bulgare des Sciences