Fluxes of CO2, CH4 and N2O from drained organic soils in deciduous forests

We examined net greenhouse gas exchange at the soil surface in deciduous forests on soils with high organic contents. Fluxes of CO₂, CH₄ and N₂O were measured using dark static chambers for two consecutive years in three different forest types; (i) a drained and medium productivity site dominated by birch, (ii) a drained and highly productive site dominated by alder and (iii) an undrained and highly productive site dominated by alder. Although the drained sites had shallow mean groundwater tables (15 and 18 cm, respectively) their average annual rates of forest floor CO₂ release were almost twice as high compared to the undrained site (1.9±0.4 and 1.7±0.3, compared to 1.0±0.2 kg CO₂ m⁻² yr⁻¹). The average annual CH₄ emission was almost 10 times larger at the undrained site (7.6±3.1 compared to 0.9±0.5 g CH₄ m⁻² yr⁻¹ for the two drained sites). The average annual N₂O emissions at the undrained site (0.1±0.05 g N₂O m⁻² yr⁻¹) were lower than at the drained sites, and the emissions were almost five times higher at the drained alder site than at the drained birch site (0.9±0.35 compared to 0.2±0.11 g N₂O m⁻² yr⁻¹). The temporal variation in forest floor CO₂ release could be explained to a large extent by differences in groundwater table and air temperature, but little of the variation in the CH₄ and N₂O fluxes could be explained by these variables. The measured soil variables were only significant to explain for the within-site spatial variation in CH₄ and N₂O fluxes at the undrained swamp, and dark forest floor CO₂ release was not explained by these variables at any site. The between-site spatial variation was attributed to variations in drainage, groundwater level position, productivity and tree species for all three gases. The results indicate that N₂O emissions are of greater importance for the net greenhouse gas exchange at deciduous drained forest sites than at coniferous drained forest sites.     

Cloning and expression of desoxyhemigossypol-6-O-methyltransferase from cotton (Gossypium barbadense)

Terpenoids play an important role in defense against insects and pathogens in cotton. These terpenoids contain phenolic groups. Metabolites in which the phenolic group has been converted to a methoxy group are less toxic to most insects and pathogens and thus may alter resistance. Here is reported the cloning of a gene from Gossypium barbadense that encodes the enzyme that methylates the phenolic group of desoxyhemigossypol (dHG) exclusively at the 6-position, dHG-6-O-methyltransferase (dHG-6-OMT). Partial peptide sequences from digests of purified dHG-6-OMT were used to design primers for RT-PCR amplification of cDNA fragments from poly(A) mRNA. Fragments were extended to full length using 5' and 3' RACE. The resulting cDNA codes for a 365-residue polypeptide with a calculated molecular weight of 40.6 kDa, in agreement with the molecular mass of purified dHG-6-OMT. When expressed in Escherichia coli, the bacterial lysates showed a high specificity for the methylation of desoxyhemigossypol, differentiating the cloned gene from other pathogen-induced methyltransferases.     

Temporal and spatial variability of total ozone content over Central Europe: analysis in respect to the biological effect on plants

The temporal and spatial variability of the total ozone content (TOC) is examined in respect to the biologically effective ultraviolet radiation on plants. TOC data from 1996 to 2000 over the domain of Central Europe were used. Variability is analysed using correlation and auto-correlation coefficients.The temporal auto-correlation analyses has shown that the only periodicity which could be found was a period of 1 year. The comparison between spatial correlation and the temporal auto-correlation delivers an equivalent value of zero for a distance between 400 and 500 km and at a time lag of 5 days. The influence of temporal and spatial variability of TOC on the biologically effective ultraviolet radiation was quantified by model calculations using action spectra of the DNA-damage and the generalised plant damage (GPD). These were undertaken for a certain location using TOC with various temporal delays or made at other locations with certain distances. The results show that the relative sensitiveness to spatial lags in TOC differs by a factor of three during the year with minimum in August and maximum around December. For temporal lags the sensitiveness changes by a factor of six between August and December.     

Seasonal effects of liming,irrigation, and acid precipitation on microbial biomass N in a spruce (Picea abies L.) forest soil

Summary Seasonal effects of liming, irrigation, and acid precipitation on microbial biomass N and some physicochemical properties of different topsoil horizons in a spruce forest (Picea abies L.) were measured throughout one growing season. The highest biomass N was recorded in autumn and spring in the upper soil horizons, while the lowest values were obtained in summer and in deeper horizons. The clearest differences between the different soil treatments were apparent in autumn and in the upper horizons. Liming increased the microbial biomass N from 1.7% of the total N content to 6.8% (Olf₁ layer) and from 1% to 2% of the total N content in the Of₂ layer. The main inorganic-N fraction in the deeper horizons was NO _inf3 ^sup- . An increase in cation exchange capacity was observed down to the Oh layer, while soil pH was only slightly higher in the Olf₁ and Of₂ layers after liming. The effects of irrigation were less marked. The microbial biomass N increased from 1.7% of total N to 4.8% in the Olf₁ layer and from 1% to 2% of total N in the Of₂ layer. In the Olf₁ layer an increase in C mineralization was observed. Acid precipitation decreased the microbial biomass N in the upper horizons from 4.8% of total N to 1.8% in the Olf₁ layer and from 2% to 0.5% in the Of₂ layer. No significant changes in soil pH were observed, but the decrease in cation exchange capacity may result in a decrease in the proton buffering capacity in the near future.     

Vitisin A content in Chilean wines from Vitis vinifera Cv. Cabernet Sauvignon and contribution to the color of aged red wines

Vitisin A was prepared from malvidin 3-glucoside and pyruvic acid in model wine medium, isolated by countercurrent chromatography, and purified by preparative high-performance liquid chromatography (HPLC). The synthesized compound was used as a reference standard to quantify vitisin A in Chilean wines from Vitis vinifera cv. Cabernet Sauvignon, including a vertical row of wines from the same vineyard over 16 years. Maximum vitisin A content was reached within the first year of storage. Importantly, up to half of the initial amount of vitisin A in young wines was still present in 15 year old wines. Although vitisin A was found to be much more stable as compared to other monomeric C-4 underivatized anthocyanins, it also slowly degrades after reaching its peak concentration. The "color activity concept" was applied to vitisin A, malvidin 3-glucoside, malvidin 3-(6' '-acetylglucoside), and polymeric pigments isolated by countercurrent chromatography in order to estimate their contribution toward the overall color expression of wines. It was found that vitisin A is only a minor contributor to the visually perceived color of aged red wines (color contribution approximately 5%). The major contributor is the polymeric fraction (color contribution approximately 70-90%).     

Increase in the prevalence of Echinococcus multilocularis infection in red foxes in Lower Saxony.]

Echinococcus multilocularis is a tapeworm having carnivores as final hosts, the red fox in particular, dog and cat less frequent. Its two host life cycle consists of a larval cycle which predominantly takes place in the liver of rodents such as mice but it can also develop in musk rats as intermediate hosts. Man can also be infected and serves as a wrong intermediate host. He develops an alveolar echinococcosis which usually ends lethal without medical treatment. The prevalence of E. multilocularis among 5.365 red foxes in Lower Saxony was monitored from 1991 to 1997. The data were analysed using spatial epidemiological methods. This evaluation is based on a significance test which was applied to the parameters of spatial autoregressive regression models (CAR) fitting to the data of two successive sampling periods from 1991-1994 and 1994-1997. The mean prevalence (spatial median) increased from 6% to 11%. The results of this epidemiological study which was restricted to Lower Saxony support for the first time the earlier reported assumption that the prevalence of foxes infected with E. multilocularis has risen in Europe in the last decade. The reasons for this development are still unknown.     

Extinction of a weakly armoured threespine stickleback (Gasterosteus aculeatus) population in Prator Lake, Alaska

Abstract –  Threespine stickleback ( Gasterosteus aculeatus ) samples from Prator Lake in southcentral Alaska consist of the relatively rare form of weakly armoured individuals with few lateral plates and no pelvic spines. Prator Lake has been sampled for threespine stickleback since 1983. Exotic northern pike ( Esox lucius ) were first observed in this lake in 1996. The appearance of pike corresponds with a dramatic decrease in stickleback numbers and apparent local extinction. The stickleback population may have been vulnerable to an exotic predator because Prator Lake lacks native piscivorous fishes, and this population had extreme armour reduction.     

Untersuchungen über die mögliche Beeinflussung der Zwischenkalbezeit bei Rindern der Rasse "Deutsche Schwarzbunte"

Die Dauer der biologischen Rastzeit ist eine variable Grβe und wird von ver-schiedenen endogenen und exogenen Faktoren beeinfluβt. Eine Rastzeit unter 60 Ta-gen ist nur bei einem kleinen Prozentsatz der Tiere als biologisch anzusehen. Eine indi-viduelle durchschnittliche Zwischenkalbezeit von 341 bis 360 Tagen ist in der Landes-zucht trotz frühzeitiger Besamung post partum nur bei einem relativ kleinen Prozentsatz zu erreichen (16,5 %). Eine individuelle durchschnittliche Zwischenkalbezeit von 361 Bis 380 Tagen dürfte als Ausdruck guter Fruchtbarkeit bei den heutigen Fütte-rungs- und Haltungsbedingungen zu werten sein. Bei einer individuellen durchschnitt-lichen Zwischenkalbezeit von 381 bis 400 Tagen liegt der Verdacht vor, daβ Fütte-rungs- und Haltungsfehler sowie Geburts- und Puerperalstörungen die Ursache der ver-langerten Zwischenkalbezeit sind. Bei Kühen mit einer sehr hohen Milchleistung kann diese Zwischenkalbezeit noch als vertretbar angesehen werden. Tiere mit einer individuellen durchschnittlichen Zwischenkalbezeit von über 400 Tagen sind im allgemeinen ats Minusvarianten hinsichtlich Fruchtbarkeit einzustufen. Dies gilt allerdings nicht für Tiere mit einer weit über dem Herdendurchschnitt liegenden Milchleistung. Eine Ver-kurzung der individuellen durchschnittlichen Zwischenkalbezeit erscheint möglich durch: Verbesserung von Fütterung und Haltung; gutes Management; Fruchtbarkeits-uberwachung; Verbesserung der Geburtshygiene; tierärztliche Überwachung von Puer-perium und Gustreit; Prophylaxe und rechtzeitige Behandlung diagnostizierter Erkran-kungen .