The characteristics of light in floral induction in vitro of Cichorium intybus. The possible role of phytochrome

The action of light in the initiation of floral buds in vitro has been studied using monochromatic light qualities on root explants of a long day plant, Cichorium intybus L. cv. Witloof. Red light (660 nm, 0.30 W m^-2) promotes flowering, while far-red (730 nm, 0.31 W m^-2) and irradiation with combined red + far-red (0.20 + 0.41 W m^-2) have no effect. In short day conditions floral response can be obtained in two ways: 1) by interrupting the dark period with 5 brief irradiations of red light (0.45 W m^-2, 12 min) at regular intervals, although these are counteracted by far-red irradiations of equal intensity and duration; 2) by interrupting the long night with 5 h red light applied during the second third of the night, while at the beginning or at the end it is ineffective. Red light efficiency appears to depend on the photosynthetic activity of the tissues, so that flowering increases with increasing intensity of white light and is suppressed if no white light is supplied. The reproductive development is determined by the coordination of proper irradiation conditions with sufficient sensitivity of the perceiving meristematic cells. The period of highest sensitivity to environmental light conditions in the life cycle of a Cichorium root explant occurs between the 8th and the 16th day after the start of the culture. The data strongly suggest that phytochrome is involved in flower induction of Cichorium in vitro.     

Plasma prolactin levels in normal children from birth to adolescence]

Plasma prolactin levels were determined by an homologous radio-immuno assay in normal children: in cord blood, at the first day of life, during childhood and along puberty. 1. In both sexes, there is a very important secretion of prolactin during the neonatal period. 2. Longitudinal studies make obvious a different pattern of plasma prolactin in boys and in girls at puberty.     

Role of endogenous adrenaline in cardiac arrhythmia induced by dichlorodifluoromethane (FC 12) in mammals]

During the inhalation of normally oxygenated gas mixtures containing light or middle concentrations of FC 12, the presence of perfused epinephrine is necessary to induce cardiac arrhythmia in rabbits and dogs. The only inhalation of normally oxygenated gas mixtures containing a very high concentration of FC 12 produces in rabbits and dogs an important decrease in arterial pressure, tachycardia, a fall in respiratory amplitude, an acceleration reflex of respiratory frequency and cardiac arrhythmia. The same experiments in baro and chemodenervated animals show that : respiratory depression due to FC 12 still occurs, but not through the arterial chemoreceptors ; tachycardia has a reflex origin : barodenervation reveals the negative chromotropic effect of FC 12 and increases the fall in arterial pressure, mainly due to the negative inotropic effect of FC 12 ; adrenaline is necessary for FC 12-induced arrhythmia : barodenervation suppresses tachycardia due to the release of endogenous epinephrine and abolishes any arrhythmia.     

Binding of adducts of NAD(P) and enolizable ketones to NAD(P)-dependent dehydrogenases

Carbonyl compounds such as alpha-ketoglutarate, pyruvate, oxaloacetate, butyraldehyde, acetaldehyde or acetone react with NAD or NADP to give adducts. Binding studies of adducts to dehydrogenases are performed by means of ultraviolet differential spectroscopy, circular dichroism and spectrofluorimetry. The dehydrogenases show a high degree of binding specificity toward the adducts which contain their specific oxidized substrate and their specific coenzyme. The high selectivity of the dehydrogenases for adducts is evidenced by binding studies of NAD(P)-pyruvate and NAD(P)-alpha-ketoglutarate adducts on glutamate dehydrogenase at pH 7.6 and 8.9. Evidence is presented showing that adducts bind to the active site of the enzymes.     

Oxysterol activation of arachidonic acid release and protaglindin E2 biosynthesis in NRK 49F cells is partially dependent on protein kinase activity

We previously demonstrated that the oxysterol potentiation of arachidonic acid release and prostaglandin biosynthesis induced by foetal calf serum activation of normal rat kidney (NRK) cells (fibroblastic clone 49F) was not related to a direct effect of oxysterols on cell free Ca²⁺ level. Since both Ca²⁺ variations and protein C are involved in arachidonic acid release in some models, we looked for a possible modulation by protein C in the oxysterol effect on arachidonic acid release. We show that when the phorbol ester 12-O-tetradecanoyl-phorbol-13acetate (TPA), a protein kinase C activator, was added to the culture medium, the oxyterol effect on arachidonic acid release and prostaglandin synthesis clearly increased. Moreover, the effect of TPA was dose-dependent and TPA EC₅₀ (4 × 10⁻⁹ M) was unchanged in the presence of the oxysterol. Preincubation of cells with TPA for 24 h prevented the arachidonic acid release induced by TPA alone, whereas the oxysterol effect was decreased but not abolished. In the absence of serum, TPA and ionomycin added together induced the same noticeable (arachidonic acid) release and PGE₂ synthesis as serum alone. Nevertheless, the potentiating effect of cholest-5-ene-3β,25-diol was much higher when serum itself was used to activate NRK cells than it was in the present serum-mimicking experimental conditions. Thus, the presence of growth factors is probably required to obtain a full oxysterol effect. We conclude that the oxysterol effect was synergistic with, but not fully dependent on, protein kinase C and Ca²⁺ ion fluxes, therefore oxysterols could affed earlier events triggered by serum growth factor binding to their cell membrane receptors.     

Serum level of 7 alpha-hydroxycholesterol in hypercholesterolemic patients treated with cholestyramine

Serum levels of 7 alpha-hydroxycholesterol (7 alpha (OH)C) were found to increase considerably in hypercholesterolemic patients treated with cholestyramine. After 3-5 days, the normal level, which is in the range of 0.04 mg/l, rose to 1 mg/l. When the treatment was stopped it decreased rapidly with a half-life analogous to that of LDLs. This phenomenon was also observed in non-hypercholesterolemic humans. More than 75% of 7 alpha (OH)C is carried in blood by the LDLs.     

Structural requirements for maximal inhibitory allosteric effect of estrogens and estrogen analogues on glutamate dehydrogenase

The inhibition of glutamate dehydrogenase by estrogens, estrogen analogues or polyphenylethylene derivatives (about one hundred molecules, most of them having estrogenic or antiestrogenic activities) was measured. The efficiency of these compounds in inducing allosteric inhibition of the enzyme was compared and correlated to their chemical structure: an aromatic ring A, a free phenolic group in the region of carbon 3 of the steroid nucleus and a lipophilic substitution in the region of C-12, C-13 or C-17 were found to be the main structural features required for maximal efficiency on glutamate dehydrogenase. A tentative model for the relative orientation of the main inhibitor families is proposed. It accounts for most of the kinetic results and can be used as a tool for the selection of affinity labels directed towards the estrogen binding site of glutamate dehydrogenase.     

Biological controls upon the physical taphonomy of exceptionally preserved salamanders from the Miocene of Rubielos de Mora,northeast Spain

McNamara, M.E., Orr, P.J., Manzocchi, T., Alcalá, L., Anadón, P. & Peñalver, E. 2011: Biological controls upon the physical taphonomy of exceptionally preserved salamanders from the Miocene of Rubielos de Mora, northeast Spain. Lethaia, Vol. 45, pp. 210–226. The middle Miocene Rubielos de Mora Konservat‐Lagerstätte of northeast Spain is hosted within profundal, finely laminated, lacustrine mudstones. The diverse biota includes abundant salamanders. Most individuals died during separate episodes and sank rapidly postmortem. Specimens are typically preserved in dorso‐ventral aspect, the most hydrodynamically stable orientation. The near‐cylindrical morphology of the body, however, allowed some carcasses to settle in or subsequently re‐orientate into, lateral orientations. Loss of skeletal elements (i.e. reduced completeness) reflects their location within the body and followed a distal to proximal trend. Two stages are identified: initial loss of a small number of phalanges, followed by loss of more proximal limb bones plus additional phalanges. Disarticulation is more complex: it occurred via several mechanisms (notably, abdominal rupture and re‐orientation of part of the body and limbs during decay) and shows no consistent pattern among specimens. The physical taphonomy of the salamanders is controlled predominantly by intrinsic biological factors, i.e. the geometry of the body and of individual skeletal elements, the orientation, inherent strength and location of specific joints and the extent to which soft tissues, particularly the skin, persist during decay. These biological factors probably control patterns of physical taphonomy of other fossil tetrapods with a similar skeletal configuration. □Articulation, completeness, Konservat‐Lagerstätten, orientation, quantitative taphonomy, salamanders.