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Projects / Programmes source: ARRS

Nutrigenomic research of oxidative stress in mice lines selected for higher and lower fat content and chickens selected on higher and lower body weight

Research activity

Code Science Field Subfield
4.02.02  Biotechnical sciences  Animal production  Animal nutrition 

Code Science Field
B400  Biomedical sciences  Zootechny, animal husbandry, breeding 

Code Science Field
4.02  Agricultural and Veterinary Sciences  Animal and Dairy science 
Keywords
nutrigenomics, oxidative stress, antioxidants, polygenic mouse model, polygenic chicken model, obesity, gene expression
Evaluation (rules)
source: COBISS
Researchers (1)
no. Code Name and surname Research area Role Period No. of publications
1.  25513  PhD Tamara Korošec  Animal production  Principal Researcher  2010 - 2012  95 
Organisations (1)
no. Code Research organisation City Registration number No. of publications
1.  0481  University of Ljubljana, Biotechnical Faculty  Ljubljana  1626914  64,298 
Abstract
The genetic selection for higher growth rate and lean yield during the last 15 years resulted in fast growing and leaner genotypes of fattening animals (especially pigs and poultry), which are, however, more sensitive to environmental stressors and disease. In intensive farming we currently face health problems due to the selection on higher lean growth, as on the other hand obesity and its related diseases cause similar health problems in companion animals and humans. Both phenomena affect the health and welfare of animals by weakening their immune system and thus making the animals more sensitive to various infections, inflammation and other disease. Oxidative stress is involved in the etiology of many diseases and pathophysiological conditions. It induces damage to important biological macromolecules, changes gene expression, affects the integrity and function of membranes, and affects immune response. Farm animals in intensive farming systems are frequently exposed to oxidative stress. The genetic differences among the members of the same species have an important impact on the response of the specimen to oxidative stress and antioxidant treatment. Thus it would be very sensible to determine the need for antioxidants in the groups of animals within species which show major differences in genotype and phenotype. Nutrigenomic studies on animals genetically selected for higher or lower fat content can help us identify the genes and mechanisms responsible for the possible different reaction of animals of the same species to oxidative stress and/or antioxidant treatment. The objective of the research on lines of mice 60 generations selected for higher or lower fat content (lines F and L) and lines of chicken 33 generations selected for higher or lower body weight (D+ in D-) is to evaluate if lean and fat animals of the same species respond differently to dietary oxidative stress. A further aim is to evaluate if the antioxidant treatment is equally effective in fat and lean animals. The proposed transcriptomic study enables us to identify differentially expressed genes involved in metabolic pathways for oxidative stress induction and genes that respond to antioxidant supplementation. A nutritional trial will be performed on F and L mouse lines and on D+ and D- chicken lines. Within each animal species, adult male animals will be assigned to six experimental groups (3 groups/line; 10 animals/group). Each line will have a control group, which will receive feed low in oxidative load (LOX). In two groups in each line dietary oxidative stress will be induced. One of the groups will serve as a positive control (HOX), the second group will be further supplemented with antioxidants (HOX+). The basic production parameters will be monitored and at the end of the feeding trial blood and tissues will be collected for further analyses. Oxidative stress will be measured by measurements of lipid peroxidation, by measurements of DNA damage, by measurements of total antioxidant status of plasma and activity of antioxidant enzymes. The basal biochemical analyses will also be performed. The analysis of whole mice and chicken genome gene expression profiling will be performed with cDNA and oligonucleotide microarrays. The analysis will be made only between groups, which will show the greatest differences between each other in phenotypic characterisation. Furthermore, we will determine the effect of oxidative stress and antioxidant treatment on the immune system and inflammatory processes in fat and lean animals. The results of oxidative stress, immune response and gene expression measurements gained on used mouse and chicken model are an important basis for further studies on other animal species and humans. If the results of this study show different responses to oxidative stress and antioxidant treatment in fat and lean animals, new dietary guidelines for antioxidant supplementation could be assessed in the future for both fenotypes.
Significance for science
The results of the study provide new knowledge on metabolism and antioxidant capacity of ?-and ?-tocopherol and their combination in vivo in chickens and in meat. The feeding of equal amounts of both forms and analysis of content in different tissues, enabled us to show how the ?-tocopherol accumulates compared with ?-tocopherol. We confirmed that ?-tocopherol more effectively accumulates in the tissues and that the upload ?-and ?-tocopherol differs among different tissues. If the ?-tocopherol is fed as the only form of vitamin E, it is converted to the ?-tocopherol during the process of metabolism. This conversion is specific for each tissue. The facts show that the intake of the combination of ?-and ?-tocopherol is more effective if compared with ?-tocopherol alone. This means that if we take into account the levels of ?-tocopherol in the feed we could add smaller amounts of ?-tocopherol to the diet. In practice this is often the case when feeding oils like corn, soy or linseed oil, which are rich in ?-tocopherol. With supplementation of a combination of ?-and ?-tocopherol (50:50) we can achieve the same effectiveness on the lipid oxidation of meat than with the same amount of alpha-tocopherol, although ?-tocopherol does not possess this capability. With the completed analysis of gene expression, we got the details on how the gene expression changes due to oxidative stress, and how ?-and ?-tocopherol and their combination affect it. By this we gaind new knowledge about the genes and metabolic pathways involved in the induction of oxidative stress by n-3 PUFA that are altered, and which are the metabolic pathways that are involved in the reduction of oxidative stress by various forms of tocopherols. We demonstrated also in our case, that one of the obvious and well-expressed paths of changes in expression of genes involved in the defense against oxidative stress is regulated via the transcription factor NRF2.The study is also methodologically important for our department as we introduce nutrigenomic techniques that until now have not been used in our laboratory.
Significance for the country
In the future it would be prudent to make new recommendations for vitamin E, which in last years represents a significant cost of feed for poultry industry. This would give a more accurate assessment of added vitamin E in relation to how much and in what form it is already present in the input feed. Today, precisely because of insufficient or contradictory information about the actual need for vitamin E in certain specific physiological conditions, surplus of this vitamin is added to feed. The research is also methodologically important for our department as we introduce nutrigenomic techniques that until now we did not use, which puts us alongside foreign institutions, and current trends in nutrition research. Without this and other modern equipment, we will stay behind, which means fewer opportunities for publication and thus for promotion and use of our knowledge in the world.
Most important scientific results Annual report 2010, 2011, final report, complete report on dLib.si
Most important socioeconomically and culturally relevant results Annual report 2010, 2011, final report, complete report on dLib.si
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