Mise en évidence d'une liaison génétique entre un gène de nanisme et des marqueurs enzymatiques chez le mil pénicillaire (Pennisetum glaucum L.)

The genetic linkage relations between the dwarfing (D2, d2) and seven enzymic marker genes were evaluated in three crosses between semidwarf and normal inbred lines of pearl millet (Pennisetum glaucum L.). The seven genes code for the following isoenzymes: alcohol dehydrogenase (Adh A), esterase (Est A), malate dehydrogenase (Mdh D) cathodic peroxydase (Pec A), phosphoglucoisomerase (Pgi A), phospholucomutase (Pgm A), and shikimate dehydrogenase (Skdh A). Semidwarf and normal plants were identified by a discriminant analysis based on 16 morphological height components. Mendelian segregations have been observed for all eight genes. Linkage was shown between Pgi A and Pgm A (4 ± 4 centimorgans (cM)), between Skdh A and Adh A (11 ± 7 cM), between D2 and Skdh A (9 ± 5 cM) and between D2 and Adh A (17 ± 8 cM). The latter three genes are linked in the following order: Adh A – 11 cM – Skdh A – 9 cM – D2. The linkage between the recessive dwarfing gene (d2) and the codominant Skdh A alleles will help in the creation of isogenic semidwarf lines of cultivars. It is highly probable that the D2d2 genotype could be separated from the D2D2 genotype.Key words: isozymes, linkage groups, early selection.

Ribonucleic acid stimulation of mammalian liver nuclear-envelope nucleoside triphosphatase. A possible enzymic marker for the nuclear envelope

1. The specific activity of rat and pig liver nuclear-envelope nucleoside triphosphatase (EC 3.6.1.3) decreases when the system is depleted of RNA. The activity can be restored by adding high concentrations of yeast RNA to the assay medium. 2. Exogenous RNA also increases the activity of the enzyme in control envelopes (not RNA-depleted). The effect appears to be largely specific for poly(A) and poly(G); it is not stimulated by rRNA or tRNA preparations, ribonuclease-hydrolysed RNA, AMP, or double- or single-stranded DNA. 3. Inhibitors of the enzyme, in concentrations at which half-maximal inhibition of the enzyme is achieved, do not affect the percentage stimulation of the enzyme by yeast RNA. 4. The simulation is abolished by the inclusion of 150 mM-KCl or -NaCl in the assay medium, but not by increasing the assay pH to 8.5. 5. The results are discussed in the light of the possible role of the nucleoside triphosphatase in vivo in nucleo-cytoplasmic ribonucleoprotein translocation. 6. It is proposed that poly(G)-stimulated Mg2+-activated adenosine triphosphatase activity should be adopted as an enzymic marker for the nuclear envelope.