Konstitution des Aldosterons,des neuen Mineralocorticoids

Summary Chemical degradation of the new crystalline mineralocorticoid provisionally called electrocortin has shown that this compound is 11, 21-dihydroxy-3, 20-diketo-4-pregnen-18-al. In solution this reacts mainly as the 11-hemiacetal. We suggest aldosterone as a definitive name for the compound.

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Über Bestandteile der Nebennierenrinde und verwandte Stoffe, 90. Mitteilung.     

Style self-incompatibility gene products of Nicotiana alata are ribonucleases

Self-incompatibility in flowering plants is often controlled by a single nuclear gene (the S-gene) having several alleles. This gene prevents fertilization by self-pollen or by pollen bearing either of the two S-alleles expressed in the style. Sequence analysis shows that three alleles of the S gene of Nicotiana alata encode style glycoproteins with regions of defined homology. Two of the homologous regions also show precise homology with ribonucleases T2 (ref. 4) and Rh (ref. 5). We report here that glycoproteins corresponding to the S1, S2, S3, S6 and S7 alleles isolated from style extracts of N. alata are ribonucleases. These style S-gene-encoded glycoproteins account for most of the ribonuclease activity recovered from style extracts. The ribonuclease specific activity of style extracts of the self-incompatible species N. alata is 100-1,000-fold higher than that of the related self-compatible species N. tabacum. These observations implicate ribonuclease activity in the mechanism of gametophytic self-incompatibility.     

Rapid changes of mitochondrial Ca2+ revealed by specifically targeted recombinant aequorin.

Introduction of Ca2+ indicators (photoproteins, fluorescent dyes) that can be trapped in the cytosolic compartment of living cells has yielded major advances in our knowledge of Ca2+ homeostasis. Ca2+ however regulates functions not only in the cytosol but also within various organelles where indicators have not yet been specifically targeted. Here we present a novel procedure by which the free Ca2+ concentration of mitochondria, [Ca2+]m, can be monitored continuously at rest and during stimulation. The complementary DNA for the Ca2+ sensitive photoprotein aequorin was fused in frame with that encoding a mitochondrial presequence. The hybrid cDNA was transfected into bovine endothelial cells and stable clones were obtained expressing variable amounts of mitochondrially targeted apoaequorin. The functional photoprotein could be reconstituted in intact cells by incubation with purified coelenterazine and [Ca2+]m could thus be monitored in situ. This allowed the unprecedented direct demonstration that agonist-stimulated elevations of cytosolic free Ca2+, [Ca2+]i, (measured in parallel with Fura-2) evoke rapid and transient increases of [Ca2+]m, which can be prevented by pretreatment with a mitochondrial uncoupler. The possibility of targeting aequorin to cellular organelles not only offers a new and powerful method for studying aspects of Ca2+ homeostasis that up to now could not be directly approached, but might also be used in the future as a tool to report in situ a variety of apparently unrelated phenomena of wide biological interest.     

Male sexual differentiation in mice lacking H-Y antigen

The sexual phenotype of an adult mammal depends on whether the fetal gonad has differentiated as a testis or as an ovary. Because individuals of XY or XXY sex chromosome constitution develop as males, while XX and XO individuals develop as females, the presence of a Y chromosome seems normally to be required for testis differentiation and its absence to be necessary for differentiation of an ovary. The nature of the hypothetical Y-dependent substance responsible for masculinization of the indifferent gonad has been a matter for debate. A male-specific transplantation antigen, H-Y, has been known for many years and more recently a serologically detected antigen, also male-specific, has been reported. Those who believe that the two are antigenically distinct refer to the latter as SDM (serologically detected male) antigen, but many refer to both as H-Y antigen. The hypothesis that H-Y is itself the Y-dependent testis inducer, although supported by little or no direct evidence, is economical and hence attractive. H-Y antigen is frequently stated to be the substance responsible for primary sex determination (for example, see ref. 11). We report here that H-Y is absent from certain mice that develop testes and are of indisputably male phenotype, hence this transplantation antigen is unlikely to be responsible for testis determination.     

INTERMEDIUM-C, a modifier of lateral spikelet fertility in barley, is an ortholog of the maize domestication gene TEOSINTE BRANCHED 1

The domestication of cereals has involved common changes in morphological features, such as seed size, seed retention and modification of vegetative and inflorescence architecture that ultimately contributed to an increase in harvested yield. In barley, this process has resulted in two different cultivated types, two-rowed and six-rowed forms, both derived from the wild two-rowed ancestor, with archaeo-botanical evidence indicating the origin of six-rowed barley early in the domestication of the species, some 8,600-8,000 years ago. Variation at SIX-ROWED SPIKE 1 (VRS1) is sufficient to control this phenotype. However, phenotypes imposed by VRS1 alleles are modified by alleles at the INTERMEDIUM-C (INT-C) locus. Here we show that INT-C is an ortholog of the maize domestication gene TEOSINTE BRANCHED 1 (TB1) and identify 17 coding mutations in barley TB1 correlated with lateral spikelet fertility phenotypes.