Beta-adrenergic receptor-linked adenylate cyclase in rat posterior pituitary

A specific β-adrenergic-stimulated cyclic AMP generating system has been evidenced in rat posterior pituitary. This is clearly demonstrated by: 1) the adenylate cyclase (AC) affinity for stimulants was in the order ISO > NA > DA, and 2) propranolol, a specific β-adrenergic receptor blocker, was the only antagonist of the system. Clonidine and apomorphine were completely inactive, thus excluding an α-adrenergic and/or dopaminergic component in this AC system. Our data also indicate that dopaminergic receptors present in both pituitary lobes are not coupled to an AC.     

Deletion ΔF508 and haplotype analysis of CFTR gene region in Slovak CF patients

Summary Analysis of a sample of 50 unrelated cystic fibrosis (CF) patients and 46 nuclear families from Slovakia (Czechoslovakia) by the polymerase chain reaction and Southern hybridization revealed that the proportion of the F508 mutation was 58% in this population, and that the frequency of the B (i.e., KM19/XV2c [1–2]) haplotype was increased in both F508 and nonF508 CF chromosomes (98% and 46%, respectively). These results support the view that the trans-European gradient of the F508 frequency is of a geographical rather than of an ethnic origin, and that in Slavonic populations, there exists an as yet unidentified but frequent CF mutation other than F508, associated with the B haplotype.     

Cell cycle regulation of the E2F transcription factor involves an interaction with cyclin A.

We have examined E2F binding activity in extracts of synchronized NIH 3T3 cells. During the G0 to G1 transition, there is a marked increase in the level of active E2F. Subsequently, there are changes in the nature of E2F-containing complexes. A G1-specific complex increases in abundance, disappears, and is then replaced by another complex as S phase begins. Analysis of extracts of thymidine-blocked cells confirms that the complexes are cell cycle regulated. We also show that the cyclin A protein is a component of the S phase complex. Each complex can be dissociated by the adenovirus E1A 12S product, releasing free E2F. The release of E2F from the cyclin A complex coincides with the stimulation of an E2F-dependent promoter. We suggest that these interactions control the activity of E2F and that disruption of the complexes by E1A contributes to a loss of cellular proliferation control.     

No evidence for linkage of autosomal dominant proximal spinal muscular atrophies to chromosome 5q markers

Summary Two recent articles have reported the linkage of a gene for recessive spinal muscular atrophy (SMA) on the chromosome region 5q11.2–13.3. Our data show no linkage of the dominantly inherited forms of SMA to this chromosome region.     

Recombinations between IRP and cystic fibrosis.

A candidate gene for cystic fibrosis was recently isolated by selective cloning of HpaII-tiny-fragment islands; it maps considerably closer to CF than does MET or D7S8 (pJ3.11), and DNA polymorphisms from this region are in marked disequilibrium with CF. cDNA cloning has shown that this protein has a growth factor-like structure and shows homology to the murine and human proto-oncogene int-1; it is designated IRP (int-1-related protein). DNA sequences from the IRP locus that recognize RFLPs are proving to be highly informative for prenatal diagnosis. We report five crossovers that have been identified which occur either within the IRP locus or between IRP and CF; these recombinants demonstrate that CF maps between the DNA markers D7S8 and KM.19.     

6β-Hydroxyipolamiide,an iridoid glucoside from Stachytarpheta mutabilis

A new iridoid glucoside has been isolated from Stachytarpheta mutabilis and assigned the structure and configuration of 6β-hydroxyipolamiide on the basis of ¹H NMR and ¹³C NMR evidence. The conversion of this compound into penta- acetyllamiol proved the above assignment.     

Benzyladenine induces the appearance of LHCP-mRNA and of the relevant protein in dark-grown excised watermelon cotyledons

Cotyledons were excised from imbibed watermelon seeds, grown for 4 days in darkness on water or 10 M benzyladenine (BA) and then tested for the presence of the light-harvesting chlorophyll a/b protein (LHCP) and its mRNA. LHCP was assayed immunologically by western blotting of SDS gels: the protein was present in plastids, but it was not recovered with the thylakoid fraction. Antibodies directed against LHCP precipitated a 32 kDa polypeptide from translation products of poly(A) RNA of cotyledons only if these had been grown on BA. Taken together the data suggest that in absence of light cytokinins are necessary for the maintenance of a detectable level of LHCP-mRNA as well as for synthesis of the protein.     

Spermatophore development and sperm ultrastructure inCraterostigmus tasmanianus (Chilopoda,Craterostigmomorpha)

 Spermatophore development and ultrastructure of the mature sperm of Craterostigmus tasmanianus were studied using light and electron microscopy. In C. tasmanianus, as in the Scolopendromorpha, the spermatophore develops within the vas deferens. The latter consists of three parts, each with a different morphology. The first may be involved in guiding the sperm to roll up into typical ring-like structures, while the other two, which show an evident secretory activity, secrete the acellular wall of the spermatophores. The ultrastructure of mature spermatozoa showed that a very close similarity exists between Craterostigmomorpha and Lithobiomorpha, especially regarding the organization of the connecting piece. Based on this similarity, we consider the Craterostigmomorpha together with the Scolopendromorpha, Geophilomorpha and Lithobiomorpha (=Pleurostigmophora) to be the sister group of the Scutigeromorpha. Accepted: 2 June 1996