Phenotypic expression of mutations in a wide-host-range R plasmid in Escherichia coli and Rhizobium meliloti.

Eight different derivatives of R plasmid RP1 with thermosensitive mutations affecting maintenance in Escherichia coli and Pseudomonas aeruginosa were introduce into Rhizobium meliloti. None of the plasmids showed a thermosensitive character in R. meliloti. On the other hand, a certain deletion mutation in RP1 was found to cause plasmid instability in rhizobia and agrobacteria, but not in E. coli.     

IS50-mediated inverse transposition. Discrimination between the two ends of an IS element

The crystal and molecular structure of l-pyroglutamyl-β-(2-thienyl)-l-alanyl-l-prolinamide, < Glu-Thi-Pro-NH₂(Thi²-TRH), C₁₇H₂₂N₄O₄S, has been determined from X-ray diffraction data. Thi²-TRH is a highly active analogue of thyroliberin, a thyrotropin-releasing hormone (TRH), in which the imidazole ring of the central histidine moiety in the natural hormone has been replaced by a 2-thienyl group. Thi²-TRH crystallizes from water in the monoclinic space group P2₁, $\text{a = 9.340(1)}\text{A}\text{?}\text{, b = 21.961(3)}\text{A}\text{?}\text{, c = 9.449(1)}\text{A}\text{?}$ and β = 109.58(1) °, with two molecules per asymmetric unit. These independent molecules, A and B, have the same general backbone conformation with the φ₂, ψ₂ and ψ₃ torsional angles close to ?90 °, +120 ° and +150 °, respectively, but they show different magnitudes of rotational disorder in the thiophene ring as well as a certain disorder in the pyrrolidine ring. A and B are cross-linked by four interchain hydrogen bonds, forming a two-stranded antiparallel β-pleated sheet structure. The molecules in these dimer fragments are further hydrogen-bonded to successive translated molecules along the a and c axes, forming a pronounced two-dimensional predominantly hydrophobic layer structure. These layers, in which the atoms are almost equally arranged on both sides, are separated by ordinary van der Waals' distances. A close correlation between the molecular conformation in the solid state and the preferential conformation in solution is found. It is concluded that the crystalline structure of Thi²-TRH possesses structural features which may be of relevance in the hormone-receptor interaction process.     

A new lethal syndrome with cloudy corneae,diaphragmatic defects and distal limb deformities

Summary Two female sibs are reported with a possibly new lethal malformation pattern, the major anomalies of which are: coarse face with small eyes and cloudy corneae, cleft soft palate, hypoplasia and absence of lobulation of both lungs, diaphragmatic defects, digitalisation of thumbs and distal limb deformities.     

A chromosomal abnormality (21q-) in primary thrombocytosis

Summary A patient with primary thrombocytosis was found to present an acquired deletion of the long arm of chromosome 21 (21q-). A similar observation reported in the literature is hereby confirmed.     

Qualitative and quantitative study of the growth and cell surface properties of Huntington's disease fibroblasts and age-matched controls

Summary Different growth-and cell surface properties of cells grown from skin biopsy samples from 25 Huntington's chorea patients, 22 at risk patients, and agematched controls were examined in a blind study. The number of explants obtained from each biopsy was carefully controlled. The nature (epithelial or fibroblastic) of the initial outgrowth was scored on all explants and the mean number of cells obtained from each explant after 3 weeks in culture was determined after trypsinization. During the next 15 passages, various parameters characterizing cell growth were studied. Maximal cell densities and growth rates were examined using a standard plating density of cells at each passage. These growth properties were also examined in three media: DME-NCS, DME-FCS, and Ham's F10 fetal calf serum (FCS). In addition, the effects of high temperature (40°C) and the addition of insulin to the medium on the growth and protein content of the cells was examined. These results, containing 152 measurements on 81 cases, were examined using a phased multivariate analysis. Blind cluster analysis showed that the clusters were nonrandomly determined. Factor analysis indicated the initial growth parameters to be among the most discriminating. Discriminant analysis, however, did not prove to be of any diagnostic use, since the external factors masked any possible genetic difference. Two possible sources of bias were identified: the size of the biopsy and the type of culture medium. The cell surface properties of HD and control fibroblasts were further investigated using two different techniques. The adhesion of single HD cells to either HD cell layers or normal cell layers revealed no significant differences. Intradermal immunization of rabbits with whole fibroblasts resulted, with both cell lines, in a polyspecific antiserum containing antibodies directed against a number of surface components. When HD and control fibroblasts were compared with the two antisera, no qualitative or quantitative differences in the precipitation patterns obtained using crossed immunoelectrophoresis, (CIE) were found. Our investigations did not allow us to discriminate HD cultures from controls by any of the qualitative and quantitative parameters tested.