Study developed at Embrapa Southeast Livestock proved that beef tenderness is directly related to the sex of the breeders. Like humans, cattle also have two copies of each of their parents' set of genes: one from their father and and one from their mother. In some cases, however, there is greater expression of paternal or maternal genes. Research has identified that variations in parent DNA affect the expression of copies of the same gene in calves. The results are relevant for breeding breeds, because there is no point in selecting a breeder if their offspring do not inherit their traits of interest, such as meat tenderness, or, in technical language: if their alleles (alternative forms of a given gene) do not manifest in progeny (offspring). “We studied the DNA variations that present this difference. Based on that, it is possible to predict whether certain traits will be more or less expressed in the animal,” says Embrapa researcher Luciana Regitano. “The research helps us understand why some traits 'skip generations’, that is, pass on from grandparents to grandchildren, but do not manifest themselves in the children,” she explains. This work was presented at the International Symposium on Animal Functional Genomics (ISAFG) in Australia. Such knowledge allows scientists to define whether the selection of a particular gene should be done paternally or maternally. It also helps to map regulatory mutations, because whenever there is such a difference in expression between the two alleles, one expects to find a mutation that affects the regulation of that gene in the neighborhood. Does softer meat depend on the bull or the cow? The research is interesting for the areas of reproduction and breeding. Even with a copy of the gene from the dam and another from the sire, there is a phenomenon observed in the last decade in which only the copy inherited from the sire (or dam) will manifest. This problem was called “imprinting” and its origin is still little known to scientists. Studies on imprinting have usually targeted diseases. One hypothesis is that as evolution progressed, organisms were unable to adapt to the diploid condition (two copies of the genome), and out of the two copies, one eventually shuts down (only one manifests itself). As an example, Regitano mentions a gene that improves meat tenderness. “The breeding process selects the animal that produces softer meat. If the expression of this animal’s gene only comes from the mother’s copy, there is no use in using a genetically improved bull and expecting his issue to produce such meat. This trait can only manifest itself in the grandchildren that are the sons of his daughters, as they will have inherited the copy of the gene from their mothers, ”explains the researcher. According to her, it is necessary to rethink how this gene will be “carried” on to future generations or to consider this when it comes to the mathematical modeling of what is expected of selection. “It is necessary to value the gain in the progeny,” the scientist asserts. Teams The research that described the unbalanced in muscle allele expression was developed during the PhD studies of the biologist Marcela Maria de Souza, who was advised by Regitano, in partnership with Simone Niciura, a researcher at the same Embrapa Unit. Meanwhile PhD candidate Marina Ibeli, also advised by Niciura, performed the description of liver unbalance, an awarded study. DNA chips relate breeder sex to herd meat quality The research used a SNP chip (called snips – a nucleotide variation, which is the basis of DNA) that contains over 700,000 snip markers for the bovine genome. This chip is used for genomic selection. “Marcela compared the chip information with that of the expressed region of the genome that produces messenger RNA, the first step toward gene expression,” Regitano details. According to the researcher, the study verified how many RNA copies of each SNP corresponded to the allele inherited from the dam and how many corresponded to the allele inherited from the sire at that stage, without worrying about production traits. “Out of this set of snips, approximately 430 were found with differences in expression between the two alleles,” she recalls. “Our goal now is to understand the cause of these differences in expression. To this end, we are investing in tests that can identify regulatory mutations that explain the behavior of alleles,” she adds. Unprecedented genetic cattle data The research developed by Marcela Souza during her PhD studies in Germany resulted in the elaboration of a compendium of bovine transcription factors, which was unprecedented in the world. As she began to study the allelic expression of genes important for beef tenderness, she realized that there was no database in the literature that was manually curated for this purpose, such as those for mice and humans. The compendium was built on the most used human database in the literature. “I contacted the bank’s author, Juan Vaquerizas, leading researcher at the Max Planck Institute for Molecular Biomedicine in Münster, Germany, who welcomed me for four months,” explains the student. “The period in Germany was not enough to analyze the 1,600 genes one by one, checking functions for which there is evidence in the literature and the domains present in the gene sequences. It was a long process until I was able to finish and publish,” she reports. The document also brings a bank of transcription cofactors, proteins that interact with the factors helping their control function over gene expression. The whole of the bovine genome is not functionally known yet and this work is a gain for the study of the genetics of these animals. In addition to added background knowledge, researchers may use the compendium instead of human or mouse databases. “But this is just the beginning, we still have many challenges ahead. One of these is the bank update, which was built on the basis of the data available in the literature at that time. Over the years, more proteins will have their functions known and the document will need to be rectified,” she ponders. Translation: Time24 News / Mariana Medeiros (editing, headline and captions)