Synthesis and evaluation of radiolabeled antagonists for imaging of beta-adrenoceptors in the brain with PET.

Five potent, lipophilic beta-adrenoceptor antagonists (carvedilol, pindolol, toliprolol and fluorinated analogs of bupranolol and penbutolol) were labeled with either carbon-11 or fluorine-18 and evaluated for cerebral beta-adrenoceptor imaging in experimental animals. The standard radioligand for autoradiography of beta-adrenoceptors, [125I]-iodocyanopindolol, was also included in this survey. All compounds showed either very low uptake in rat brain or a regional distribution that was not related to beta-adrenoceptors, whereas some ligands did display specific binding in heart and lungs. Apparently, the criteria of a high affinity and a moderately high lipophilicity were insufficient to predict the suitability of beta-adrenergic antagonists for visualization of beta-adrenoceptors in the central nervous system.     

Gibberellin and phytochrome control senescence in alstroemeria leaves independently

In alstroemeria ( Alstroemeria hybrida ), leaf senescence is effectively retarded by the application of gibberellins and by low fluences of red light. In this study we examined the possible interaction of gibberellins and red light in the regulation of senescence. Determination of endogenous gibberellins revealed that leaf senescence is accompanied by significant changes in the concentrations of non‐ 13‐hydroxylated gibberellins, the onset of senescence coinciding with a dramatic drop in GA₄, whereas concentrations of 13‐hydroxylated gibberellins are far less influenced. However, no direct effect of red light on a specific GA‐metabolic step could be determined. When exogenously applied, non‐13‐hydroxylated GAs were more active than the 13‐hydroxylated GAs. It appeared that the effect of red light is additive to that of active GAs. We hypothesise that GA₄ and phytochrome control senescence in alstroemeria mainly through separate mechanisms and have independent effects and that the observed differences in gibberellin concentrations are a consequence of delayed leaf senescence rather than a cause for it.     

Growth and reproduction in culture of ten Phytophthora fragariae races

Cultural characteristics were employed to develop a basis for characterizing each of the ten recognized races ofPhytophthora fragariae Hickman in the United States. Investigations were made into the relationships of temperature to growth and colony morphology, the effects of various media and ß-sitosterol on growth and oospore production, and relative zoosporangium production capabilities of the ten races. On the basis of this information, the ten races were divided into two groups according to their colony morphologies. Further characterization was possible on the basis of differential oospore and zoosporangium production in different media, and, to a lesser extent, with contrasting increments in mycelial mass and linear extension.     

Mutant of Escherichia coli K-12 Defective in the Transport of Basic Amino Acids

Escherichia coli K-12 possesses two active transport systems for arginine, two for ornithine, and two for lysine. In each case there is a low- and a high-affinity transport system. They have been characterized kinetically and by response to competitive inhibition by arginine, lysine, ornithine and other structurally related amino acids. Competitors inhibit the high-affinity systems of the three amino acids, whereas the low-affinity systems are not inhibited. On the basis of kinetic evidence and competition studies, it is concluded that there is a common high-affinity transport system for arginine, ornithine, and lysine, and three low-affinity specific ones. Repression studies have shown that arginine and ornithine repress each other's specific transport systems in addition to the repression of their own specific systems, whereas lysine represses its own specific transport system. The common transport system was found to be repressible only by lysine. A mutant was studied in which the uptake of arginine, ornithine, and lysine is reduced. The mutation was found to affect both the common and the specific transport systems.     

Keraladiaptomus rangareddyi a new genus and new species of Diaptominae (Copepoda,Calanoida, Diaptomidae) from a temporary pond in Mattam,Kerala State,India

Calanoid copepods, belonging to the new genus and species Keraladiaptomus rangareddyi, were collected from temporary ponds in Kerala State, India. The new genus belongs to the family Diaptomidae, subfamily Diaptominae. It is described in detail and its affinity to the related genera, Arctodiaptomus Kiefer, 1932 and Eodiaptomus Kiefer, 1932, discussed.     

Manganese absorption by excised barley roots

Short-term absorption studies with 5-day-old excised barley roots revealed that the basic aspects of Mn absorption were similar to those of other metabolically absorbed cations. Following an initial non-metabolic equilibration with the root, Mn was absorbed for several hours at a slower steady-state rate comparable to that of other inorganic cations. Complete or nearly complete inhibition of the steady-state phase by low temperature, dinitrophenol, and azide provides strong evidence that Mn transport into this tissue was metabolically mediated. Within limits, the rate of transport was strongly dependent upon the concentrations of Mn and the hydrogen ions in the ambient solution. Absorption increased rapidly with increasing concentrations of Mn up to 1 meq per liter. Above this concentration, the rate leveled off, apparently due to a saturation of the transport mechanism. Within the physiological pH range in which Mn is soluble (below pH 7), absorption increased greatly with decreasing hydrogen-ion concentration.     

Archaic and contemporary topographic diversification of Upper Mississippi River forests

Topographic diversity is an important component of environmental heterogeneity. Topographic diversity within the Upper Mississippi River floodplain has been degraded because of modifications for navigation improvement. Efforts aimed at restoring topographic diversity in the Upper Mississippi River floodplain have been extensive but have not focused on reversing the effects of forest loss and degradation. We investigated habitat features associated with Cerulean Warbler (Setophaga cerulea) locations both within and outside of river floodplains and hypothesized this species would select topographically diverse habitats. Both topographic diversity and the distance to the upland forest/floodplain forest interface were useful predictors of Cerulean Warbler presence. We conclude that incorporation of topographic diversity into floodplain forest restoration planning would likely benefit Cerulean Warblers and the other species with similar habitat requirements. Incorporating topographic diversity into floodplain forest conservation planning will be challenging on major rivers that serve multiple purposes.