Abstract: The present invention concerns a polypeptide comprising the N-terminal fragment of a cystatin, and/or a cystatin expression inducer for use for the treatment of sterility and/or infertility, and a method of diagnosing and/or predicting sterility and/or infertility of a subject and/or of a couple of subjects, which method comprises measuring the level of at least one cystatin in a biological sample of a male subject and/or measuring the level of at least one cystatin in a biological sample of a female subject, and optionally measuring further the level of at least one cathepsin in a biological sample of said male of female subject.

Abstract: A method for labeling a product includes a step of adding on or in the product a plurality of single-stranded polynucleotides, which plurality of polynucleotides includes at least one target polynucleotide constituted of a single-stranded polynucleotide of predetermined length and sequence, and decoy polynucleotides which have identical or different predetermined lengths and identical or different predetermined sequence, which decoy polynucleotides have a length or lengths identical to or different from and sequences different from the sequence of the at least one target polynucleotide, wherein each of the target and decoy polynucleotides does not hybridize with any of the other polynucleotides of the plurality of polynucleotides and wherein the polynucleotides of the plurality of polynucleotides are deoxyribonucleic or ribonucleic acid sequences, respectively having the same proportion of the four, natural or modified, bases A, C, G, and T, or A, C, G and U.