Dušan Terčič

Catalog of genetic variants within mature microRNA seed regions in chicken

MicroRNA (miRNA) is a class of noncoding RNA important in posttranscriptional regulation of target genes. The regulation mechanism requires complementarity between target mRNA and the miRNA region responsible for their recognition and binding, also called the seed region. It has been estimated that each miRNA targets approximately 200 genes and genetic variability of miRNA genes has been associated with phenotypic variation and disease susceptibility in humans, livestock species, and model organisms. Polymorphisms in miRNA genes especially within the seed region could therefore represent biomarkers for phenotypic traits important in livestock animals. Using the updated Version 5.0 of our previously developed bioinformatics tool miRNA SNiPer we assembled polymorphic miRNA genes in chicken. Out of 740 miRNA genes 263 were polymorphic, among them 77 had SNPs located within the mature region, and 29 of them within the miRNA seed region. Because several polymorphisms in databases result from sequencing errors, we performed experimental validation of polymorphisms located within 4 selected miRNA genes in chicken (gga-mir-1614, −1644, −1648, and −1657). We confirmed the presence of nine polymorphisms and identified 3 additional novel polymorphisms within primary miRNA regions in chicken representing 3 layer-type breeds, one layer-type hybrid, and one meat-type intercrossed population. The developed catalog of mir-SNPs in chicken can serve researchers as a starting point for association studies dealing with poultry production traits and designing functional experiments.

External, Internal and Sensory Qualities of Table Eggs as Influenced by Two Different Production Systems

This study was conducted to determine the effects of two production systems (organic vs conventional cages) on egg quality parameters during the late laying period. The effects of a production system were investigated on external and internal quality and on the sensory attributes. The eggs produced in organic system had paler yolks (P<0.001) and thinner egg shells (P<0.05) than the eggs produced in the cages. Overall sensory quality was improved in eggs deriving from hens allocated in cages. Differences between organic and cage eggs indicated lower redness and higher yellowness (P<0.001) in organic eggs than in cage eggs. The organic eggs were characterised by a higher content of a-linolenic and docosapentaenoic acid (P<0.05) and lower content of linoleic acid (P<0.05) than the eggs from cages. The ratio of omega fatty acids, n-6/n-3, was most favourable in the organic eggs (5.93:1). In the cage eggs, the ratio n-6/n-3 was significantly (P<005) higher (955:1).