Morphogenese bei Pisum sativum als Reaktion auf minimale P 730-Konzentration

Summary Growth of the petioles of etiolated pea seedlings is enhanced by very low doses of red or by a broad range of far-red energies. However, red energies which establish the photostationary steady state fail to enhance this growth or can even inhibit it. This inhibitory effect can be reversed by far-red (Fig. 2). This result is explained by the assumption that the optimum concentration of P₇₃₀ for growth is very low. This optimum concentration depends on how often the induction is repeated.In contrast, all other photoresponses in peas show the well-known dose-response relationship, as can be demonstrated, e.g., for the growth of internodes (Fig. 1).

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Mit Unterstützung der Deutschen Forschungsgemeinschaft.     

Developmental Physiology Apparent Dark Decay of Phytochrome Pfr in Fern Spores

Germination of spores of Dryopteris fllix-mas has been induced by two pulses of saturating red light, separated by a dark period of about 8 to 24 h. By chosing different wavelengths, different P_fr/P_tot levels could be established. Thus, by a “null method” the second pulse could be used as a “test pulse”, determining the actual P_fr level remaining from the “start pulse”, and thus providing information about an apparent Pf_r decay. It cannot be decided yet whether this apparent P_fr decay results from dark destruction or dark reversion. The apparent P_fr decay depends, as expected, on the temperature, being accelerated with increasing temperatures. Moreover, the later after sowing that the decay is tested, the faster it proceeds; a tentative interpretion is that newly synthesized P_r undergoes faster decay after phototransformation than that phytochrome pool present in the resting spores. A third factor that influences the apparent P_fr decay is the Pf_r/P_tot level established by the first pulse (start pulse). The lower this level, the slower the decay kinetics. This could be due to phytochrome biosynthesis partly compensating for P_fr destruction, and the relative contribution of this biosynthesis to the total effect increases with lower P_fr levels. Spores of D. paleacea yield virtually the same results. Whatever the real basis of the observed P_fr decay, i.e. destruction, reversion, or a combination of these reactions with biosynthesis, it can be concluded that modification of this P_fr decay by various factors is the basis of the effect of those factors on light-induced germination.     

PML tumour suppression and beyond: Therapeutic implications

Recognition of the tumour suppressive capacity of the Promyelocytic Leukemia protein (PML) has emerged beyond its identification through APL, to a broad spectrum of tumors. This ability has chiefly been linked to its role as a core component of dynamic structures termed PML Nuclear Bodies (PML-NBs). In response to a variety of stresses, key factors and their molecular modifiers are recruited to PML-NBs, where activating modifications are facilitated, leading to a cellular stress response. PML was also found to perform anti-tumourigenic functions through cytoplasmic activities. Surprisingly, important recent research defined growth promoting capabilities of PML, which significantly challenges the notion of a ‘classic’ tumour suppressor. Through metabolic reprogramming, PML can afford a selective advantage for tumor cells in certain settings. The multiple forms in which PML exists are the likely explanation of this functional diversity. This behavioral ambiguity however raises a significant challenge to the design of strategies to therapeutically target PML. In this review we discuss this change of paradigm in the PML field and its ramifications, particularly for tailoring cancer therapies.     

A simple chemical method for the synthesis of catechol estrogens

The preparation of 2-hydroxyestrone, 2-hydroxyestradiol-17, 4-hydroxyestrone and 4-hydroxyestradiol-17β by a simple one-step chemical reaction, treatment with potassium nitrosodisulfonate, is described. The structures of the products were established by nmr, ultraviolet, infrared and mass spectra as well as from their chemical and chromatographic properties.     

Exploring the human lacrimal gland using organoids and single-cell sequencing

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