Reproductive biology in the primitive relic AngiospermDrimys brasiliensis (Winteraceae)

From field observations onDrimys brasiliensis, principally in the Botucatu region of São Paulo State, Brazil, new data on the reproductive biology, the rhythm of growth, and the development of lateral cymose inflorescences, flowers and fruits are presented. Pollination accelerates the rate of flower-development for about 4–6 days. Pollination experiments show thatD. brasiliensis is not self-sterile; because of mechanical devices the sticky pollen grains do not normally come into contact with the stigmata unless an animal pollen vector is involved. The pollinators are diurnalColeoptera, Diptera andThysanoptera which eat from the pollen, lick from the stigmatic exudates and (in case of the flies) probably also from the staminal glands. Fruit- and seedeaters are birds which seem to be the main dispersal agents. Establishment of new individuals normally is through seedlings, but also by vegetative propagation through plagiotropous branches which may root and separate from the mother plant. The morphological, developmental and reproductive aspects inD. brasiliensis are discussed in a wider context, compared with data from otherMagnoliidae, and related to aspects of early Angiosperm evolution.     

Mutationsversuche an Kulturpflanzen

Zusammenfassung Die im Jahre 1951 zunächst allgemein gegen die RassenA undD nachgewiesene Mehltauresistenz von 8 röntgeninduzierten Wintergerstenmutanten ist differenziert und erweitert worden. Mut. 501 ist gegen 10 von 14 untersuchten Rassen der RassengruppenA, D, B undC resistent (A ₁,A ₂,A ₃,A ₄,D ₁,D ₃,B ₂,B ₃,C ₂,C ₃) und gegen vier anfällig (B ₅,B ₆,C ₄,C ₅). Die übrigen 7 Mutanten 511, 512, 513, 514, 515, 520 und 525a zeigen übereinstimmendes Resistenzverhalten: Von den 16 untersuchten Rassen der RassengruppenA, D, B, C sind die Mutanten gegen acht resistent (A ₂,A ₅,D ₁,B ₂,B ₃,B ₇,C ₂,C ₄) und für die anderen acht anfällig (A ₁,A ₃,A ₄,D ₃,B ₅,B ₆,C ₃,C ₅). Die Mutanten stellen durch diese ihnen eigentümliche, bisher nicht bekannte Kombination der Resistenz gegen verschiedene Rassen vonErysiphe graminis hordei wertvolle Differentialwirte dar.Die Genetik der Mehltauresistenz ist bei den acht Mutanten für die RasseA ₂ untersucht worden. Zwei unabhängige Gene sind nachgewiesen: eines bedingt die Resistenz von Mut. 501 (Obsistens) und ein zweites diejenige der übrigen sieben Mutanten 511, 512, 513, 514, 515, 520, 525a (Resistens). Diese sieben Mutanten sind also bzgl. der Mehltauresistenz genetisch identisch, während Mut. 501 heterogen ist. Vererbt wird die Mehltauresistenz bei allen acht Mutanten monogen und vollständig bzw. unvollständig dominant. Lediglich Mut. 520 scheint sich labil zu verhalten. alle Mutanten zeigen zusätzliche Merkmalsänderungen.     

Experimente zur Wirkung von Actinomycin D auf die durch Phytochrom bewirkte Anthocyansynthese

Summary Phytochrome-mediated anthocyanin synthesis of the mustard seedling can be blocked by moderate concentrations of Actinomycin D (10 g/ml in the solution around the seedling) if the substance is applied before the onset of far-red light (Fig. 1). If, however, the seedlings are irradiated with far-red for 6 hours, transferred to the dark for one hour, incubated with Act. D for 3 hours (in the dark) and then re-irradiated with continuous far-red, anthocyanin synthesis can only partially be inhibited (Fig. 2). — There are good arguments that the physiological action of the small stationary concentration of P₇₃₀ which is left in the plant after we turn off the far-red light will virtually stop at the moment when the light is turned off (Wagner and Mohr, 1966a). Furthermore the P₇₃₀-dependent mRNAs which are involved in anthocyanin synthesis seem to be shortlived (Lange and Mohr, 1965; Mohr and Senf, 1966; Durst and Mohr, 1966). Considering these arguments and the results of the present paper we cannot but conclude that genes which have once been activated by P₇₃₀ will not return to the original state—at least with respect to Act. D sensitivity—even when the activating (or de-repressing) agent (P₇₃₀ in our case) has disappeared.

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Experimente zur Wirkung von Actinomycin D auf die durch Phytochrom bewirkte Anthocyansynthese

     

Unterschiedliche photoperiodische Empfindlichkeit der beiden Blattseiten von Kalanchoe blossfeldiana

Summary The short-day plant Kalanchoe blossfeldiana was grown on short photoperiods and was given supplementary light of low intensity (4–7 lux). If the supplementary light was supplied to the upper sides of the leaves flowering was strongly inhibited. Irradiation of the lower sides was much less effective.     

Positive selection for Dictyostelium discoideum mutants lacking UMP synthase activity based on resistance to 5-fluoroorotic acid

Summary In the cellular slime mould Dictyostelium discoideum the two enzymatic activities of the pyrimidine pathway, orotidine-5-phosphate decarboxylase (EC 4.1.1.23; OMPdecase) and orotate phosphoribosyl transferase (EC 2.4.2.10; OPRTase), are encoded by a single gene (DdPYR5-6). As in higher eukaryotes the bifunctional enzyme is referred to as UMP synthase. Here we present a method that allows efficient generation and selection of mutants lacking UMP synthase. D. discoideum cells are transformed with either of two different types of plasmids. One plasmid type contains no sequences homologous to the UMP synthase gene whereas the other type contains at least parts of this gene. UMP synthase^– mutants, which were positively selected for in the presence of 5-fluoroorotic acid (5-FOA), were obtained with both plasmids. However, mutation rates were at least one order of magnitude higher if plasmids containing various portions of the UMP synthase gene were used as opposed to plasmids that lack any homology to the UMP synthase locus. Several mutant strains were extensively characterized. These strains lack OMPdecase activity and exhibit in addition to 5-FOA resistance a ura ^– phenotype. All mutants carry UMP synthase loci with deletions of various extents but integration of transforming plasmids was not detected. This efficient generation of 5-FOA resistance is part of a proposed complex selection scheme which allows multiple rounds of transformation of D. discoideum.     

Heterotypic induction of stomach-like glands in the urogenital sinus endoderm under the influence of stomach mesenchyme of foetal rats

Summary Urogenital sinus endoderm of 16.5-day rat foetuses was combined with stomach mesenchyme and the recombinants were either treated with testosterone and grown in vitro or cultured beneath the kidney capsule of adult male rats of the same strain. It was found that testosterone stimulated mitosis in the urogenital endoderm. In recombinants grown under the kidney capsule a stratified squamous epithelium and stomach-like glands were induced under the influence of the forestomach and glandular stomach mesenchymes. However, the induced glands expressed neither rat pepsinogen nor rat ventral prostatic antigen. They did not produce mRNA for the prostatic steroid-binding protein C1. Thus, stomach mesenchyme of rat foetuses induces organ-specific morphogenesis but not functional differentiation in the heterologous endoderm, indicating that cytodifferentiation does not always accompany morphogenesis.     

Gonadotropes in a novel rat pituitary tumor cell line,RC-4B/C. Establishment and partial characterization of the cell line

Summary An epithelial cell line (RC-4B/C) was established from a pituitary adenoma obtained from a 3-yr-old (ACI/fMai × F344/fMai)F1 male rat. Before Year 5 in vitro, RC-4B/C cells could not be viably recovered from cryogenic storage. Recovery of viable cells from cryogenic storage in Year 5 was associated with a more transformed phenotype, including the appearance of endogenous C-type rat retroviral particles. The ultrastructural appearance of the cells was similar to that of differentiated anterior pituitary cell; the cultured cells contained numerous, electron dense, secretory granules, Golgi complexes, and extended arrays of rough endoplasmic reticulum. Immunocytochemical study showed that all cell types present in the rat anterior pituitary gland were present in the cell line. The percentage of luteinizing hormone beta (LHβ) cells in the cell line was higher (19.9%) and that of growth hormone cells was lower (12.2%) than in normal male rat pituitary, whereas the cell line contained a comparable percentage of follicle stimulating hormone beta (FSHβ), prolactin (PRL), ACTH, and thyrotropin beta cells. Radioimmunoassay data demonstrated the PRL content of the cells was comparable to that of normal male rat pituitary gland, whereas the content of LH and FSH was 70- and 800-fold lower, respectively. Assay of specific receptor sites for gonadotropin releasing hormone (GnRH) using Scatchard plots of the data established the RC-4B/C cells contained GnRH receptor sites of the same affinity as in the pituitary gland, but of twofold lower capacity. These data suggest the RC-4B/C cell line warrants further study as a model for the induction and maintenance of the gonadotropic function of the pituitary gland. An abstract of portions of these results was presented at the 8th International Congress of Endocrinology, Kyoto, Japan, 1988. This work was supported in part by grants DK-17631 (E.H.L.), CA-24145 (W.G.B.), CA-31102 (H.G.B.), AG-01753 (D.E.H.) and HD-1778 (M.T.D.) from the National Institutes of Health, Bethesda, MD, and by a grant from the Association pour la Recherche sur le Cancer, France (M.J.). The NIH is not responsible for the contents of this publication nor do the contents necessarily represent the official views of that agency. Jolanta Polkowska was a recipient of a Foundation Simone et Cino del Duca grant.