Discrimination of direct and indirect interactions in a network of regulatory effects.

The matter of concern are algorithms for the discrimination of direct from indirect regulatory effects from an interaction graph built up by error-prone measurements. Many of these algorithms can be cast as a rule for the removal of a single edge of the graph, such that the remaining graph is still consistent with the data. A set of mild conditions is given under which iterated application of such a rule leads to a unique minimal consistent graph. We show that three of the common methods for direct interactions search fulfill these conditions, thus providing a justification of their use. The main issues a reconstruction algorithm has to deal with, are the noise in the data, the presence of regulatory cycles, and the direction of the regulatory effects. We introduce a novel rule that, in contrast to the previously mentioned methods, simultaneously takes into account all these aspects. An efficient algorithm for the computation of the minimal graph is given, whose time complexity is cubic in the number of vertices of the graph. Finally, we demonstrate the utility of our method in a simulation study.     

Illustrated keys to the anopheline mosquitoes of Myanmar.

In the newly revised and illustrated keys to 4th instar larvae and adult female mosquitoes, the following 36 Anopheles species from Myanmar are included: Anopheles aconitus, An. aitkenii, An. annularis, An. argyropus, An. barbirostris, An. bengalensis, An. culicifacies, An. dirus, An. fluviatilis, An. gigas, An. insulaeflorum, An. jamesii, An. jeyporensis, An. karwari, An. kochi, An. kyondawensis, An. lindesayi, An. maculatus, An. majidi, An. minimus, An. nigerrimus, An. nitidus, An. pallidus, An. peditaeniatus, An. philippinensis, An. pseudojamesii, An. sinensis, An. splendidus, An. stephensi, An. subpictus, An. sundaicus, An. tessellatus, An. theobaldi, An. vagus, An. varuna, and An. willmori. The new keys presented in this paper will enable public health workers to rapidly identify mosquito vectors of malaria and to distinguish them from other species in the same genera.     

Selenium in chronic neurologic diseases

The selenium levels in whole blood and the activity of glutathione peroxidase in hematogenous cells of normal Danes have been defined taking into account sex and confounding factors such as smoking and aging. No differences related to sex could be found with regard to the selenium level, and peroxidase activity assayed with hydrogen peroxide. However, the peroxidase activity assayed with t-butyl hydroperoxide was higher in females than in males (p<.05). The peroxidase activities are dependent on age. Thus, the peroxidase levels assayed with both substrates show a minimum value in the age group from 40 to 50 yr for both smokers and nonsmokers. Smokers did show more homogeneous values as a function of age than nonsmokers. Smokers had significantly lower selenium values than nonsmokers, but glutathione peroxidase values identical with those of nonsmokers. Multiple sclerosis (MS) patients suffer from a chronic relapsing/remitting demyelinating disease. A theory explaining the pathogenesis of MS concerns increased stickiness of cellular plasma membranes, hampering normal vascular function of the brain. In agreement with that theory, the present communication demonstrates significantly lowered selenium values and lowered glutathione peroxidase activities of major types of hematogenous cells. In close agreement with these findings, hematogenous cells in MS show increased peroxidation rates. A nonblinded biochemical dietary experiment on MS patients showed that all abnormalities could be normalized by daily intake of selenium, vitamin E, and vitamin C. Batten’s disease is a recessive inherited neurodegenerative disorder clinically characterized by progressive loss of vision, epilepsy, and dementia. Neuropathologically, this disease is characterized by storage of lipofuscin in nervous tissue. We have in a few cases documented a low selenium status and low glutathione peroxidase activities of hematogenous cells. As in MS, we normalized the biochemical abnormalities by an antioxidative treatment. Like in similar Finnish studies, the biochemical parameters can be normalized. Further, the Finnish studies indicate it possible by an antioxidative treatment to inhibit progression of the mental deterioration. The data presented will be discussed in relationship both to specific pathological parameters of the diseases and to the low dietary energy expenditures of handicapped immobile patients.     

An alignment of 17 deduced protein sequences from plant,fungi, and ciliate H+-ATPase genes

Seventeen protein sequences of H⁺-ATPases from plants (Arabidopsis thaliana, Nicotiana plumbaginifolia, Lycopersicum esculentum), fungi (Sacharomyces cerevisiae, Schizosaccharomyces pombe, Zygosaccharomyces rouxii, Neuropora crassa, Candida albicans), and a parasitic ciliate (Leishmania donovani) have been aligned. Twenty sequence fragments were identified which were conserved in H⁺-, Na⁺/K⁺-, and Ca⁺⁺ plasma membrane-ATPases. In addition, a total of 118 residues not located in these fragments were found to be conserved in all H⁺-ATPases. Among those, 38 amino acid residues were screened out as being priority targets for site-directed mutagenesis experiments aimed at the identification of the amino acid residues specifically involved in cation specificity.     

The properties of photoreconvertible fluorophore systems in insect eyes resemble those of quinones

Summary Photoreconvertible fluorophore systems were found in the superposition compound eyes of the mothDeilephila and the neuropterAscalaphus. The systems are very similar to those first described by Schlecht et al. (1987) on the apposition eye of the blowflyCalliphora. The fluorophore systems in the cone cells ofDeilephila andAscalaphus closely agree with those in the Semper cells ofCalliphora. In all 3 species the primary fluorophore is converted by UV into a blue-absorbing fluorophore with its _max in the range between 410 and 450 nm. The intensity of the fluorescence from the photoproducts in all 3 pigment systems is highly dependent on pH; maximal intensity is recorded if pH5. The pK point is at 6.0 (Deilephila). The fluorescence from the Semper cells (and rhabdomeres) inCalliphora is maximal at low retinoid content showing that the chromophoric group of the fluorophore systems is not a retinoid. The probable candidates for the chromophoric group in these systems are quinones, like ubiquin-one. Phospholipid vesicles into which ubiquinone has been incorporated have fluorophore characteristics comparable to those of the fluorophores in the compound eyes: photoreconversion is induced by UV and blue light, the excitation maxima of the primary and secondary fluorophore are similar, and the intensity of the fluorescence from the secondary fluorophore is highly dependent on pH. The intensity of the fluorescence from the vesicles also depends on the direction of the pH gradient across the membrane, suggesting that this pH dependence is due to an asymmetric distribution of the quinone rings at the inner and outer membrane surface.     

Anticipated yield loss in field-grown soybean under elevated ozone can be avoided at the expense of leaf growth during early reproductive growth stages in favourable environmental conditions

Ozone is a powerful oxidizing agent which is responsible for more damage to vegetation than any other air pollutant. In this study, leaf growth, photosynthesis, and carbohydrate content were analysed during the seed-filling growth stage of field-grown soybeans exposed to ambient air and 1.2 times ambient ozone concentration using a Free Air Concentration Enrichment (FACE) facility. By contrast to predictions based on controlled-environment and open-top chamber studies, final yield did not differ between treatments, although the cultivar used here was sensitive to ozone damage: growth and carbohydrate content of upper canopy leaves was reduced during the seed-filling stage in which an ozone-induced decrease of photosynthesis was present. However, 2004 was an ideal growing season in central Illinois and the cumulative ozone indices were lower than in previous years. Still, the results indicate that the anticipated yield loss under ozone concentrations was avoided at the expense of leaf growth, as reserves were diverted from vegetative to reproductive organs.     

Wie wachsen Tropenbäume? Jahrringe als Ausdruck von Klimabedingungen und Lebensform

Growth of tropical trees is largely depending on the seasonality of the local climate. In many trees growing in areas with a distinct dry season, cambial activity ceases resulting in the formation of annual rings. In very humid mountain rainforests, trees stop to grow already after short rainless periods. By a combination of increment measurements and wood anatomical analyses, the climatic control of wood formation can be assessed. Intra‐annual wood density variations and content of various stable isotopes enable the climatological interpretation of the “wood signals”.     

Greifvögel und Pestizide

Birds of prey and pesticides During the years of 1940 to the 1960ties the use of persistent organic pestcides (POP's) became common. DDT was used widely to kill pest insects in farming and forrestry. This resulted in the so called “pesticide chrash” in many bird populations namely in Peregrines and Ospreys. These species were poisoned via their food webs, from insects to birds or fish which had accumulated POP's like DDT. Between 1970 and 2004 all POP's were banned and since 1970 the populations grew again supported by nature conservation and wildlife management. Nowadays new generations of pesticides are in use, which are less persitant but still highly toxical for birds of prey. Therefore we need to control them by biomonitoring of relevant species like peregrine falcons and others.     

Siphonodictyal B1 from a Marine Sponge Increases Intracellular Calcium Levels Comparable to the Ca2+-ATPase (SERCA) Inhibitor Thapsigargin

Siphonodictyal B1 is a sesquiterpene-hydroquinone isolated from the Caribbean coral reef bioeroding sponge Siphonodictyon coralliphagum. Siphonodictyal B1 increased intracellular calcium levels in neuroendocrine cells (PC12) in the presence and absence of extracellular calcium using Fura-2 as a calcium-sensitive dye. The calcium rise was comparable in amplitude and timing to the application of the sarco-endoplasmic reticulum calcium-ATPase (SERCA) inhibitor thapsigargin from the terrestrial plant Thapsia garganica. The effects of thapsigargin and siphonodictyal B1 on intracellular calcium levels were not distinguishable in pharmacological experiments conducted with caffeine, ryanodine, muscarine, and thapsigargin in calcium-free and calcium-containing buffer, although thapsigargin was effective at lower concentrations. Thapsigargin is a sesquiterpene-lactone and has no structural similarities to siphonodictyal B1. We conclude that thapsigargin and siphonodictyal B1 share SERCAs as cellular targets. Siphonodictyal B1 may be involved in the process of bioeroding the calcium carbonate endoskeleton of the scleractinian corals attacked by S. coralliphagum.