Early expression of the KAL gene during embryonic development of the chick.
The human KAL gene is responsible for the X chromosome-linked Kallmann syndrome, which consists of the association of hypogonadotropic hypogonadism and anosmia. The human and chicken KAL genes have been isolated. Using in situ hybridization, we studied KAL gene expression during development of the chick. We have previously reported that, from embryonic day 8, the expression is almost restricted to definite neuronal populations in the central nervous system, most of which still express the gene after hatching. Here we report that the KAL gene is also expressed during early embryonic development (days 2-8) in various endodermal, mesodermal, and neurectodermal derivatives. In most endodermal and mesodermal derivatives, the expression is transient and precedes cell differentiation. In contrast, the expression in the nervous system concerns postmitotic central neuroblastic populations, most of which still express the gene after differentiation. In accordance with such a spatio-temporal pattern of expression, we suggest that the KAL gene is involved both in morphogenetic events and in neuronal late differentiation. In addition, the absence of detectable expression of the KAL gene either in the embryonic olfactory epithelium or in the surrounding nasal mesenchyme reinforces the hypothesis that Kallmann's syndrome results from a central olfactory target cell defect.
Legouis
R
R
Unité de Génétique Moléculaire Humaine (CNRS URA 1445), Institut Pasteur, Paris, France.
Hardelin
J P
JP
Petit
C
C
Ayer-Le Lièvre
C
C
D000818:Animals; D001483:Base Sequence; D002642:Chick Embryo; D018076:DNA, Complementary / Q000096:biosynthesis; D004627:Embryonic Induction / Q000235:genetics; D016326:Extracellular Matrix Proteins; D018507:Gene Expression Regulation, Developmental / Q000235:genetics*; D017403:In Situ Hybridization; D017436:Kallmann Syndrome / Q000235:genetics*; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000235:genetics*; D013997:Time Factors; D014960:X Chromosome
C076266:ANOS1 protein, human; D018076:DNA, Complementary; D016326:Extracellular Matrix Proteins; D009419:Nerve Tissue Proteins