Abstract: A method of fragmenting a DNA sequence having a starting size of at least 10000 base pair into fragments having a mean size smaller than or equal to 1300 bp, wherein the DNA sequence is put in a solution, the solution comprising the DNA sequence is put in a container and the container is placed in a liquid bath which is subjected to the action of ultrasound waves such that the ultrasound waves travel through the liquid bath to excite the container and the solution so as to shear the DNA sequence, and wherein the ultrasound waves have a frequency falling in the range between 28 kHz and 80 kHz.

Abstract: A method of fragmenting a DNA sequence having a starting size of at least 10000 base pair into fragments having a mean size smaller than or equal to 1300 bp, wherein the DNA sequence is put in a solution, the solution comprising the DNA sequence is put in a container and the container is placed in a liquid bath which is subjected to the action of ultrasound waves such that the ultrasound waves travel through the liquid bath to excite the container and the solution so as to shear the DNA sequence, and wherein the ultrasound waves have a frequency falling in the range between 28 kHz and 80 kHz.

Abstract: A gene (cDNA) encoding a bovine myostatin protein. The nucleic acid coding sequence is identified as SEQ ID NO:1 and the protein sequence is identified as SEQ ID NO:2. A mutant gene (SEQ ID NO:3) in which the coding sequence lacks an 11-base pair consecutive sequence (SEQ ID NO:11) of the sequence encoding bovine protein having myostatin activity has been sequenced. It has been shown that cattle of the Belgian Blue breed homozygous for the mutant gene lacking myostatin activity are double-muscled. A method for determining the presence of muscular hyperplasia in a mammal is described. The method includes obtaining a sample of material containing DNA from the mammal and ascertaining whether a sequence of the DNA encoding (a) a protein having biological activity of myostatin, is present, and whether a sequence of the DNA encoding (b) an allelic protein lacking the activity of (a), is present. The absence of (a) and the presence of (b) indicates the presence of muscular hyperplasia in the mammal.