Localisation régionale des gènes humains IDHS,MDHS, PGK, α-GAL,G6PD par l'hybridation cellulaire interspécifique

Summary 22 independent man-hamster (HGPRT^–) hybrids using male human cells with balanced reciprocal translocation t(X;2)(p22;q32) were analysed for human genes localized on chromosome 2 (IDH_S, MDH_S), on chromosome X (PGK, GAL, G6PD) and for the different chromosomes in relation with the balanced reciprocal translocation (chr.2, chr.2q^–, chr.Xp⁺).The following results were obtained:The chromosomes 2 and 2q^– are absent in the 22 hybrids.In 9 hybrids, the absence of MDH_S in spite of the presence of the chromosome Xp⁺ indicates that the gene for MDH_S is not localized on this chromosome (or that the gene for MDH_S is not on the segment 2q32-2qter translocated on X).In 14 hybrids, the three markers of X (PGK, GAL, G6PD) and IDH_S are expressed in the presence of the chromosome Xp⁺. This result indicates that the genes for these markers are on Xp⁺ or that the genes PGK, GAL, G6PD are on X without the Xp22-Xter segment, translocated on the chr.2, and that the gene for IDH_S is on the 2q32-2qter segment translocated on X.In 8 hybrids, in the absence of the intact chromosome Xp⁺, the higher percentage of the presence of G6PD (7 hybrids) and the lower percentage of the presence of IDH_S (3 hybrids) are explained by the fact that these hybrids selected in HAT medium had to retain a segment of Xp⁺ bearing the human gene HGPRT. G6PD appeared very close to HGPRT and IDH_S very distant from HGPRT.The study of the different correlations between the presence and the absence of these four markers on Xp⁺ in the different hybrids indicates the following order on the chromosome Xp⁺ from p to q: IDH_s — PGK — GAL — G6PD.

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Groupe INSERM: Directeur J. Frézal

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Groupe CNRS, ER, 149: Directeur J. de Grouchy     

Partial 9q trisomy associated with a 9,21 translocation

Summary A new case of partial trisomy 9q was found in a child presenting two de novo aberrations: a deletion of the long arms of 9 and a 9,21 translocation. A tentative cytogenetic explanation is put forward.     

Alcaloides du Strychnos tchibangensis

The structure of a new bisindole alkaloid has been elucidated by chemical correlation and analysis of ¹³C NMR spectra.     

Biochemical characterization of propionyl CoA carboxylase deficiency: Heterogeneity within a single genetic complementation group

Liver tissues and fibroblasts from patients with propionic acidemia assigned to the pcc BC genetic complementation group have previously been shown to contain normal or near-normal quantities of structurally altered propionyl CoA carboxylases (PCC). Biochemical comparisons of PCCs from extracts of three livers and one placenta belonging to the pcc BC complementation group revealed that the K _m values for the enzyme's major substrates, propionyl CoA, bicarbonate, and ATP, and its monovalent activator, potassium, were similar to those of normal PCC. PCC in extracts of one of the livers, however, had an altered isoelectric point (pI = 5.4) compared to that of PCC from normal and other PCC-deficient tissues (pK = 4.6–4.7). Thermostability in the presence of sucrose or ATP differed among several of the mutant PCCs, including the PCC with an altered pI, and from that of normal PCC. To confirm these results and to determine whether valid inferences may be derived from comparisons of mutant and normal PCC in crude extracts, PCC was purified from normal liver and from one of the PCC-deficient livers. The biochemical parameters of the purified carboxylases were similar to those observed in liver extracts. These studies further-more confirmed that, whether purified or in extracts, PCC from the pcc BC group reflects structural mutations. Nevertheless, the abnormal enzyme structure appears to have no corresponding effect on the clinical features of the disorder in various affected individuals. Moreover, there is biochemical heterogeneity within the pcc BC complementation group that probably represents different interallelic gene mutations.This work was supported by NIH Research Grants Am 25675 and AM 26127. B. Wolf is the recipient of NIH Research Career Development Award AM 00677 and is aided by Basil O'Connor Starter Research Grant 5-263 from The National Foundation-March of Dimes. This article is No. 131 from the Department of Human Genetics at the Medical College of Virginia.     

2-Heptanone Production by Spores of Penicillium roquefortii in a Water-Organic Solvent Two-Phase System

The production of 2-heptanone from octanoic acid may be performed by free and entrapped spores of Penicillium roquefortii in a water-organic solvent two phase system.

An industrial, isoparafflnic solvent, i.e. Hydrosol IP 230 O.S., which may be considered as tetradecane, is well suited for the process. Activities nearly double those achieved with aqueous systems are observed using an initial fatty acid content in the organic layer close to 100 mM and a ratio of the volume of the organic phase to the total volume of the medium of 0.88. The presence of the solvent allows a better recovery of the metabolite by lowering its activity coefficient.

Fed-batch experiments performed in an aerated, stirred reactor show that the bioconversion may proceed in the two-phase system for at least 300 h. These conditions allow conversion of 750 mM (108 g · 1^-1) fatty acid, and production of 600 mM (68.5 g · 1^-1) 2-heptanone.     

Embryogenesis in the Presence of Blockers of Mechanosensitive Ion Channels

Certain developmental events are thought to be controlled by mechanical tension, but the nature of the transduction mechanism for sensing and responding to tension changes is unknown. A good candidate for such a sensing system would be stretch-activated (SA) ion channels, a type of mechanosensitive (MS) ion channel found in many preparations including the oocytes or embryos of ascidians, fish, and amphibians. To test the hypothesis that SA channel activation is important for early embryogenesis, we treated amphibian and ascidian eggs and embryos with inhibitors of MS ion channels. Xenopus laevis eggs and embryos were treated with gadolinium (Gd³⁺) concentrations up to 100 times the K_d for SA channel inhibition. Boltenia villosa eggs and embryos were exposed to three agents (Gd³⁺, tubocurarine, and gallamine) which are known to block SA channels in other organisms. None of these drugs interfered with morphogenesis in a manner that would suggest SA channel activity is critical to early embryogenesis.