Stable carbon cycle-climate relationship during the Late Pleistocene

A record of atmospheric carbon dioxide (CO2) concentrations measured on the EPICA (European Project for Ice Coring in Antarctica) Dome Concordia ice core extends the Vostok CO2 record back to 650,000 years before the present (yr B.P.). Before 430,000 yr B.P., partial pressure of atmospheric CO2 lies within the range of 260 and 180 parts per million by volume. This range is almost 30% smaller than that of the last four glacial cycles; however, the apparent sensitivity between deuterium and CO2 remains stable throughout the six glacial cycles, suggesting that the relationship between CO2 and Antarctic climate remained rather constant over this interval.     

Carbon isotope constraints on the deglacial CO₂ rise from ice cores

The stable carbon isotope ratio of atmospheric CO(2) (δ(13)C(atm)) is a key parameter in deciphering past carbon cycle changes. Here we present δ(13)C(atm) data for the past 24,000 years derived from three independent records from two Antarctic ice cores. We conclude that a pronounced 0.3 per mil decrease in δ(13)C(atm) during the early deglaciation can be best explained by upwelling of old, carbon-enriched waters in the Southern Ocean. Later in the deglaciation, regrowth of the terrestrial biosphere, changes in sea surface temperature, and ocean circulation governed the δ(13)C(atm) evolution. During the Last Glacial Maximum, δ(13)C(atm) and atmospheric CO(2) concentration were essentially constant, which suggests that the carbon cycle was in dynamic equilibrium and that the net transfer of carbon to the deep ocean had occurred before then.     

Die Behandlung von berindetem Nutzholz mit Insektiziden. Versuche mit verschiedenen Wirkstoffen in Schweden 1969–73

Insecticide treatment of unbarked conifer logs. Experiments with various substances in Sweden 1969–73 In 1969–73 the protection of unbarked pine and spruce logs by means of insecticides was studied at several localities in Sweden. Investigations have been carried out into the effect of eleven substances and various combinations, as well as formulations and concentrations, upon the attacks of bark beetles and other insects. More than 2 100 logs were used in the experiments. Lindane was by far the most effective. It had also a very good effect upon the beetles which entered or had entered the wood. All the carbamates studied, i. e. BPM-carbamate, carbaryl, mobam, promecarb, and propoxur, as well as the organophosphorous compounds Bayer 77488, fenitrothion, and fenthion, had an unsatisfactory effect. Endosulfane was not ineffective, but the tests were discontinued. Dursbane was studied on spruce only and had a good effect. One year after the treatment, lindane did no longer give reliable protection. After treatment in the autumn it protected against bark beetles on spruce in the spring, but had less effect on pine. There was no considerable difference in the effect of wettable powder and emulsion concentrate. In some cases wettable powder had a slightly better effect. The lowest suitable concentration was about 0,25%.     

Species-specific recognition of single-stranded RNA via toll-like receptor 7 and 8

Double-stranded ribonucleic acid (dsRNA) serves as a danger signal associated with viral infection and leads to stimulation of innate immune cells. In contrast, the immunostimulatory potential of single-stranded RNA (ssRNA) is poorly understood and innate immune receptors for ssRNA are unknown. We report that guanosine (G)- and uridine (U)-rich ssRNA oligonucleotides derived from human immunodeficiency virus-1 (HIV-1) stimulate dendritic cells (DC) and macrophages to secrete interferon-alpha and proinflammatory, as well as regulatory, cytokines. By using Toll-like receptor (TLR)-deficient mice and genetic complementation, we show that murine TLR7 and human TLR8 mediate species-specific recognition of GU-rich ssRNA. These data suggest that ssRNA represents a physiological ligand for TLR7 and TLR8.     

Selection of cell-lines and regeneration of plants resistant to fusaric acid from Gladiolus × grandiflorus cv. ‘Peter Pears’

Cell suspension cultures of ‘Peter Pears’, a cultivar of Gladiolus x grandiflorus (Hort.), susceptible to the fungus Fusarium oxysporum f. sp. gladioli (Mass.), have been challenged with fusaric acid, one of the toxins produced by this pathogen. Selected cell-lines showed increased tolerance to the toxin and grew even on concentrations of fusaric acid up to 0.5 mm. When inoculated with a conidial suspension, the mycelial growth on selected cell-lines was limited compared to the control. Fusaric acid greatly reduced plant regeneration, and only two plants were obtained from the callus subcultured for a prolonged time on medium with fusaric acid. These plants have a significantly altered DNA content compared to the control. A reduced callus phase on toxin-containing medium, resulted in an improved regeneration and the DNA content of the regenerated plantlets was similar to the control. Some plants regenerated from these fusaric acid-insensitive cell-lines showed an increased tolerance to the toxin when cultured in vitro in presence of fusaric acid. The selected plants will be further tested for Fusarium-resistance once maturity is reached. This revised version was published online in July 2006 with corrections to the Cover Date.     

30,000 years of cosmic dust in Antarctic ice

Polar ice provides an archive for the influx of cosmic dust. Here, we present a high-resolution, glacial-to-interglacial record of cosmic dust using helium isotope analysis of the European Project for Ice Coring in Antarctica (EPICA) ice core drilled in Dronning Maud Land. We obtained a relatively constant 3He flux over the past 30,000 years. This finding excludes 3He as a pacemaker of late Pleistocene glacial cycles. Rather, it supports 3He as a constant flux parameter in paleoclimatic studies. A last glacial-to-Holocene shift of the 4He/non-sea salt Ca2+ ratio appears to indicate a glacial-to-interglacial change in the terrestrial dust source.     

Zur unterschiedlichen Resistenz von Lärchen gegen Läusebefall

Zusammenfassung In einer Plantage mit Klonen vonLarix sibirica undL. decidua in Nordschweden wurden Unterschiede zwischen den Klonen im Befall vonAdelges laricis festgestellt. In einer Lärchenplantage in Mittelschweden warL. decidua stark von überwinternden Hiemalis-Larven derA. laricis befallen, während asiatische Lärchen weitgehend verschont blieben. Europäische Lärchen von zwei Herkünften unterschieden sich deutlich in der Stärke und der Verteilung des Befalls. Ein Einfluß der Rindendicke oder -struktur auf den Läusebefall konnte nicht nachgewiesen werden.

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Summary Differences in attack by the aphidAdelges laricis Vallot were found between clones in a clonal plantation ofLarix sibirica andL. decidua in northern Sweden. In a plantation of larch in central SwedenL. decidua was heavily attacked by hibernating larvae ofA. laricis, whereas asiatic larch of various origins bore only a very low level of infestation. Two origins of European larch displayed differences both in degree as well as in distribution of aphid attack. Neither bark thickness nor structure could be shown to influence attack.

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Résumé Les diffèrents degrès d'attaque parAdelges laricis sur plusieurs clônes deLarix sibirica etLarix decidua ont été déterminés dans un plantage de Suède du nord (5 mètres d'équidistance entre les plans). Dans un plantage semblable de mélèze en Suède centrale,Larix decidua était fortement attaqué par des chenilles hivernantes d'Adelges laricis alors que les mélèzes asiatiques de diffèrentes provenances n'étaient que peu touchés. Deux origines diffèrentes de mélèze d'Europe présentaient de notables variations quant à la force et la répartition de l'attaque. Une influence de lépaisseur de l'écorce ou de sa structure sur l'attaque des pucerons ne pouvait être mise à jour.

     

Prevalence and significance of gastrointestinal helminths and protozoa in South American Camelids in Switzerland

A cross sectional study was conducted to determine the prevalence and significance of endoparasitic infections in South American Camelids (SAC) in Switzerland. Qualitative and quantitative coproscopic examinations were performed in 38 farms during the grazing period. Management practices with possible interference with parasitic infections were analyzed. On the farm level prevalences of endoparasitic infections were: trichostrongyles 87%; Trichuris sp. 74%; Capillaria sp. 68%; Nematodirus battus 63%; Nematodirus sp. 53%; Dicrocoelium dendriticum 34%; Moniezia sp. 8%; Fasciola hepatica 5%; protostrongylids 5%; Eimeria macusaniensis 68%. The level of helminth egg excretion was generally low. The highest values were recorded for trichostrongyles with an average of all investigated farms of 53 eggs per gram of faeces. The mean trichostrongyle egg output was approximately three-fold in SAC on farms that also kept sheep and/or goats, although this difference was not significant (P = 0.11). Clinical trichostrongylidosis was not reported from any of the farms. The low infection level with gastrointestinal nematodes is attributed to the defaecation behaviour of the SAC depositing their faeces focally on small spots on pasture. As a consequence, pasture infectivity is largely restricted to the area adjacent to the dung piles. Dicrocoeliosis is regarded as the most relevant parasitic infection of llamas and alpacas in Switzerland causing severe clinical symptoms and death in untreated animals. Sixteen per cent of the owners regularily treated their herds against dicrocoeliosis using praziquantel at a dose of 50 mg/kg body weight orally.     

Efficacy of leaf extract fractions of Glycyrrhiza glabra L. against downy mildew of cucumber (Pseudoperonospora cubensis)

An ethanolic leaf extract of Glycyrrhiza glabra L. (licorice) was highly effective in former bioassays and semi-commercial trials in controlling cucumber downy mildew (efficacy up to 99.0?% in bioassays and 83.0?% in semi-commercial trials). In order to elucidate the active ingredients and the mode of action, licorice leaf extract was fractionated into six fractions of defined substance classes, of which the fraction containing acidic substances (F6) showed highest efficacy (97.6?%). The calculated EC₅₀ values after a probit analysis of concentration series of crude extract and fraction F6 were concentrations of 1.0?% (crude extract) and 0.6?% (fraction F6). Interestingly, the slopes of the resulting graphs were significantly different, pointing to different modes of action for the two treatments. Three flavonoid compounds could be detected. The substances were glabranin, licoflavanon and pinocembrin. All three are known for their antimicrobial and antifungal capacity against plant and human pathogens. Besides these flavonoids, results, such as the different EC₅₀ values, indicated that other compounds may be involved in the activity of fraction F6 against P. cubensis on cucumber.     

High-resolution Greenland ice core data show abrupt climate change happens in few years

The last two abrupt warmings at the onset of our present warm interglacial period, interrupted by the Younger Dryas cooling event, were investigated at high temporal resolution from the North Greenland Ice Core Project ice core. The deuterium excess, a proxy of Greenland precipitation moisture source, switched mode within 1 to 3 years over these transitions and initiated a more gradual change (over 50 years) of the Greenland air temperature, as recorded by stable water isotopes. The onsets of both abrupt Greenland warmings were slightly preceded by decreasing Greenland dust deposition, reflecting the wetting of Asian deserts. A northern shift of the Intertropical Convergence Zone could be the trigger of these abrupt shifts of Northern Hemisphere atmospheric circulation, resulting in changes of 2 to 4 kelvin in Greenland moisture source temperature from one year to the next.