Identification of differentially expressed genes in lines of Japanese quail divergently selected for high and low four-week body weight
Mott, Ivan W
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Poultry production is of worldwide economic importance as a valuable source of high protein food. Understanding the genetic mechanisms that control growth and muscle mass deposition may lead to production of animals that produce larger, leaner cuts of meat for human consumption, facilitate selective breeding schemes that would increase genetic heterozygosity while maintaining desirable growth traits, as well as contribute to general knowledge regarding muscle biology and disease. Decades of selective breeding have produced lines of fast-growing, high muscle bearing chickens that are found in today’s broiler industry. Growth-selected lines of Japanese quail have been developed as a model system to aid in the study of poultry breeding and selection issues. These lines have been selected for high and low 4-week body weight. Myostatin is a negative regulator of muscle mass and mutations in this gene give rise to two independently derived European breeds of cattle that have larger, leaner muscle fibers than other cattle breeds with wild type myostatin. This work analyzes the expression pattern of myostatin in different lines of growth-selected chickens and quail to determine if it has been selected against during decades of selective breeding. It is shown here that with respect to myostatin there have been no mutations in the DNA coding sequence, no changes in transcript levels, and no differences in the protein levels between the control and selected lines. DNA array analysis was used to identify genes that were differentially expressed between lines of Japanese quail. Random anonymous quail cDNA clones (4,704) were robotically spotted to nylon membranes and screened using isotopically-labeled whole quail embryo cDNA from the different lines. Three cDNAs were identified as having substantial differences in expression. Expression levels were confirmed by Northern blotting, and nucleotide sequences were obtained and annotated. Analysis was also done using CyDye-labeled proteins and two-dimensional polyacrylamide gel electrophoresis to identify four proteins that were differentially expressed in liver from the different quail lines.