Abstract: The probe comprises: a) an oligonucleotide or oligodeoxyribonucleotide part constituted by a DNA or RNA nucleic acid sequence S, depending on the type of molecule to be detected, and b) a non-nucleotide part possessing chemical properties enabling direct or indirect atttachment of one or more detection units or marking elements M detectable non-isotopically by production of colour or light. The probe is characterized by the fact that part b) is constituted by a chain of phosphate units interspersed with alkyl groups, viz.: b1) certain alkyl groups uniting the different phosphate groups and presenting no special functionality b2) alkyl groups presenting primary amine groups which allow splicing with varied reagents to carry out direct or indirect detection, the b2) groups being bonded to part a) or sequence S by way of groups b1). Sequence S is bonded at its 5' and/or 3' extremity to one or more marking elements M.

Abstract: The subject of the present invention is a nucleic acid probe containing a nucleic acid sequence, wherein the said sequence is linked at its 5' end, via a divalent bifunctional chemical "arm" L, to a "labeling component" M, M being a synthetic or natural molecule which is directly or indirectly detectable in a non-isotopic manner, according to the formula I: ##STR1## in which J=H or OHn denotes the number of nucleotides from 1 to 100,000B is a purine or pyrimidine nucleic acid base, which varies according to the nucleotide, as appropriate.The subject of the invention is also a process for preparing such probes, employing an intermediate compound consisting of a nucleotide synthon of formula IV ##STR2## in which J, B, L and R.sub.1 have the meanings given above, B optionally being protected,R.sub.2 denotes H or any phosphorylated group, optionally protected, suited to the introduction of the compound of formula IV at the 5' end of another nucleotide, for a given type of internucleotide-assembling synthesis.