U zadnjih 15 godina došlo je do razvoja novog načina analize utjecaja gena na proizvodna svojstva svinja. Intenzivni uvjeti proizvodnje doveli su do iskorištavanja genetskog potencijala svinja u pogledu poboljšanja njihovih proizvodnih i reproduk¬tivnih svojstava. Razvoj novih metoda analize genoma omogućuje ostvarenje po¬stavljenih ciljeva. Definiciju epigenetike postavio je Waddington 1940. godine. Pojmom „epigenetika“ objašnjava se kontrola „iznad“ gena, odnosno utjecaj okolišnih čimbenika na regulaciju genske ekspresije. Ona se temelji na izučavanju nasljednih varijacija ekspresije gena koje se odvijaju bez promjene DNA sekvence. Imprinti¬rani geni nastaju kao posljedica epigenetskih modifikacija koje uključuju metilaci¬ju DNA ili posttranslacijske modifikacije histona. Kemijski dodaci na molekuli DNA koji mijenjaju molekulu DNA stvaraju epigenom. Promjene epigenoma mogu se dogoditi zbog utjecaja okoliša ili mutacija. Iako su prisutna oba alela nekog gena, samo je jedan od njih izražen, dok je drugi neaktivan. Do sada je identificirano 120 imprintiranih gena kod čovjeka i miša, 10 kod ovaca, 7 kod goveda i 22 kod svinja. Zastupljenost imprintiranih gena u genomu je teško utvrditi zbog specifičnosti tkiva i stadija razvoja. Prvi otkriveni imprintirani gen je IGF2. To je gen izražen preko oca, a njegov utjecaj kod svinja ogleda se u svojstvima mišićne mase i odlaganja masnog tkiva. Genetski imprinting ima utjecaj na proizvodna svojstva. Debljina leđne slanine, tjelesna masa i rast svojstva su pod utjecajem imprintiranih gena. Imprintirani geni najveći utjecaj imaju na prenatalni i neonatalni rast. Razumijevanje aktivnosti imprintiranih gena koje nosi svinja bit će moguće tek razvojem metoda njihove analize.Over the past 15 years of a new way in analyzing the impact of genes on production traits in swine developed. Intensive production conditions have led to the exploitation of the swine genetic potential in the improvement of their productive and reproductive traits. The development of new methods for analysing the genome provides the realization of planned goals. Definition of epigenetics was set by Waddington in 1940. The term “epigenetics” explains control “over the genes” and the influence of environmental factors on the regulation of gene expression. It is based on the study of inherited variations in gene expression that occur without changes in DNA sequence. Imprinted genes occur as a result of epigenetic modifications that
include DNA methylation and histone post-translational modifications. Chemical additions on the DNA that alter DNA molecule create epigenom. Changes in epigenom can occur because of environmental factors impact or mutations. Although both allele of a gene are present, only one of them is expressed, while the other is inactive.
Until now, 120 imprinted genes have been identified in humans and mouse, 10 in sheep, 7 in cattle and 22 in pigs. The presence of imprinted genes in genome is difficult to determine because of their presence in specific tissues and development stages. First discovered imprinted gene was IGF2. This gene is expressed through the father and his influence in swine is reflected on the properties of muscle and
adipose tissue. Genetic imprinting has great influence on production traits. Back fat thickness, body weight and growth are characteristics affected by imprinted genes. Imprinted genes have the greatest influence on the prenatal and neonatal growth. Understanding the activities of imprinted genes will be possible only with the development
of methods of their analysis
