Ein Beitrag zur Bekämpfung der Fritfliege in der Roggenzüchtung

Ohne ZusammenfassungMit 2 Abbildungen     

European springtime temperature synchronises ibex horn growth across the eastern Swiss Alps

Direct effects of climate change on animal physiology, and indirect impacts from disruption of seasonal synchrony and breakdown of trophic interactions are particularly severe in Arctic and Alpine ecosystems. Unravelling biotic from abiotic drivers, however, remains challenging because high‐resolution animal population data are often limited in space and time. Here, we show that variation in annual horn growth (an indirect proxy for individual performance) of 8043 male Alpine ibex (Capra ibex) over the past four decades is well synchronised among eight disjunct colonies in the eastern Swiss Alps. Elevated March to May temperatures, causing premature melting of Alpine snowcover, earlier plant phenology and subsequent improvement of ibex food resources, fuelled annual horn growth. These results reveal dependency of local trophic interactions on large‐scale climate dynamics, and provide evidence that declining herbivore performance is not a universal response to global warming even for high‐altitude populations that are also harvested.     

T Cell-Specific Overexpression of TGF?1 Fails to Influence Atherosclerosis in ApoE-Deficient Mice

Clinical data have indicated a negative correlation between plasma TGFß1 concentrations and the extent of atherosclerosis and have thus led to the hypothesis that the pleiotropic cytokine may have anti-atherogenic properties. T-cells are currently discussed to significantly participate in atherogenesis, but the precise role of adaptive immunity in atherogenesis remains to be elucidated. TGFß1 is known to strongly modulate the function of T-cells, however, inhibition of TGFß1 signalling in T-cells of atherosclerosis-prone knock-out mice failed to unequivocally clarify the role of the cytokine for the development of atherosclerosis. In the present study, we thus tried to specify the role of TGFß1 in atherogenesis by using the murine CD2-TGFß1 transgenic strain which represents a well characterized model of T-cell specific TGFß1 overexpression. The CD2-TGFß1 transgenic mice were crossed to ApoE knock-out mice and quantity and quality of atherosclerosis regarding number of macrophages, smooth muscle cells, CD3 positive T-cells and collagen was analyzed in CD2-TGFß1 ApoE double mutants as well as non-transgenic ApoE controls on both normal and atherogenic diet of a duration of 8, 16 or 24 weeks, respectively. In all experimental groups investigated, we failed to detect any influence of TGFß1 overexpression on disease. Total number of CD3-positive T-lymphocytes was not significantly different in atherosclerotic lesions of CD2-TGFß1 ApoE^−/− females and isogenic ApoE^−/− controls, even after 24 weeks on the atherogenic diet. The synopsis of these data and our previous study on TGFß1 overexpressing macrophages suggests that potential effects of TGFß1 on atherosclerosis are most probably mediated by macrophages rather than T-cells.     

Influence of Starvation on Potential Ammonia-Oxidizing Activity and amoA mRNA Levels of Nitrosospira briensis

The effect of short-term ammonia starvation on Nitrosospira briensis was investigated. The ammonia-oxidizing activity was determined in a concentrated cell suspension with a NO_x biosensor. The apparent half-saturation constant [K_m(app)] value of the NH₃ oxidation of N. briensis was 3 μM NH₃ for cultures grown both in continuous and batch cultures as determined by a NO_x biosensor. Cells grown on the wall of the vessel had a lower K_m(app) value of 1.8 μM NH₃. Nonstarving cultures of N. briensis showed potential ammonia-oxidizing activities of between 200 to 250 μM N h⁻¹, and this activity decreased only slowly during starvation up to 10 days. Within 10 min after the addition of fresh NH₄⁺, 100% activity was regained. Parallel with activity measurements, amoA mRNA and 16S rRNA were investigated. No changes were observed in the 16S rRNA, but a relative decrease of amoA mRNA was observed during the starvation period. During resuscitation, an increase in amoA mRNA expression was detected simultaneously. The patterns of the soluble protein fraction of a 2-week-starved culture of N. briensis showed only small differences in comparison to a nonstarved control. From these results we conclude that N. briensis cells remain in a state allowing fast recovery of ammonia-oxidizing activity after addition of NH₄⁺ to a starved culture. Maintaining cells in this kind of active state could be the survival strategy of ammonia-oxidizing bacteria in nature under fluctuating NH₄⁺ availability.     

Degradation of apoptotic cells and fragments in HL-60 suspension cultures after induction of apoptosis by camptothecin and ethanol

Early indicators of apoptosis in mammalian cells are membrane potential breakdown (loss) in mitochondria (MPLM), chromatin condensation, DNA degradation, and phosphatidylserine exposure (PSE) on the outside plasma membrane. One aim of the present study was to determine the kinetics of these characteristics. These changes were measured by flow cytometry using the following methods: membrane potential of mitochondria was analysed using Mito Tracker Green and Red, PSE was analysed using annexin-V-FITC staining simultaneously with propidium iodide (PI) to detect membrane permeability; chromatin condensation was measured using the acid denaturation Acridine Orange (AO) method; DNA degradation was studied by the sub G1 method and the terminal transferase dUTP nick end-labelling (TUNEL) assay (labelling of strand breaks). HL-60 cells were induced to apoptosis by 3% ethanol and 1.5 microM camptothecin (CAM) and the kinetics of the apoptotic cells were measured. The same kinetics were found for chromatin condensation and DNA degradation indicating that these changes appeared at approximately the same time after induction. The MPLM and PSE kinetics showed a considerably later increase indicating that MPLM occurred downstream of DNA degradation and that plasma membrane changes occurred downstream of MPLM. The main aim of the study was to follow the fate of apoptotic cells after the appearance of the initial characteristics. The lifetime of apoptotic cells was studied by chase experiments. The inducing drug was removed after 4 h treatment and the disappearance of apoptoses recorded. An exponential decay was measured with a half life (T(1/2)) of 17.8 h. As a corollary from these experiments, camptothecin was found to induce apoptosis also in G1 and G2 phase cells, however, it took much longer to occur than in S phase cells. Using labelling of the plasma membrane with a fluorescent cell membrane linker, it was possible to show that the majority of apoptotic bodies as well as condensed apoptotic cells contain DNA and membrane. The degradation of these apoptotic bodies follows similar kinetics as those of the condensed apoptotic cells. The membrane remained considerably stable, there was no further loss in the next 7 days, after the first day when the apoptotic characteristics develop. It is concluded that the apoptosis programme is completed within a day and no further steps follow.     

Frequency analysis of atrial fibrillation from the surface electrocardiogram

Atrial fibrillation (AF) is the most common arrhythmia encountered in clinical practice. Neither the natural history of AF nor its response to therapy are sufficiently predictable by clinical and echocardiographic parameters. Atrial fibrillatory frequency (or rate) can reliably be assessed from the surface electrocardiogram (ECG) using digital signal processing (filtering, subtraction of averaged QRST complexes, and power spectral analysis) and shows large inter-individual variability. This measurement correlates well with intraatrial cycle length, a parameter which appears to have primary importance in AF domestication and response to therapy. AF with a low fibrillatory rate is more likely to terminate spontaneously, and responds better to antiarrhythmic drugs or cardioversion while high rate AF is more often persistent and refractory to therapy. In conclusion, frequency analysis of AF seems to be useful for non-invasive assessment of electrical remodeling in AF and may subsequently be helpful for guiding AF therapy.     

Influence of O2 availability on NO and N2O release by nitrification and denitrification in soils

The availability of O₂ is believed to be one of the main factors regulating nitrification and denitrification and the release of NO and N₂O. The availability of O₂ in soil is controlled by the O₂ partial pressure in the gas phase and by the moisture content in the soil. Therefore, we investigated the influence of O₂ partial pressures and soil moisture contents on the NO and N₂O release in a sandy and a loamy silt and differentiated between nitrification and denitrification by selective inhibition of nitrification with 10 Pa acetylene. At 60% whc (maximum water holding capacity) NO and N₂O release by denitrification increased with decreasing O₂ partial pressure and reached a maximum under anoxic conditions. Under anoxic conditions NO and N₂O were only released by denitrification. NO and N₂O release by nitrification also increased with decreasing O₂ partial pressure, but reached a maximum at 0.1–0.5% O₂ and then decreased again. Nitrification was the main source of NO and N₂O at O₂ partial pressures higher than 0.1–0.5% O₂. At lower O₂ partial pressures denitrification was the main source of NO and N₂O. With decreasing O₂ partial pressure N₂O release increased more than NO release, indicating that the N₂O release was more sensitive against O₂ than the NO release. At ambient O₂ partial pressure (20.5% O₂) NO and N₂O release by denitrification increased with increasing soil moisture content. The maximum NO and N₂O release was observed at soil moisture contents of 65–80% whc and 100% whc, respectively. NO and N₂O release by nitrification also increased with increasing soil moisture content with a maximum at 45–55% whc and 90% whc, respectively. Nitrification was the main source of NO and N₂O at soil moisture contents lower than 90% whc and 80% whc, respectively. Higher soil moisture contents favoured NO and N₂O release by denitrification. Soil texture had also an effect on the release of NO and N₂O. The coarse-textured sandy silt released more NO than N₂O compared with the fine-textured loamy silt. At high soil moisture contents (80–100% whc) the fine-textured soil showed a higher N₂O release by denitrification than the coarse-textured soil. We assume that the fine-textured soil became anoxic at a lower soil moisture content than the coarse-textured soil. In conclusion, the effects of O₂ partial pressure, soil moisture and soil texture were consistent with the theory that denitrification increasingly contributes to the release of NO and in particular N₂O when conditions for soil microorganisms become increasingly anoxic.     

Response of high-sensitive C-reactive protein to catheter ablation of atrial fibrillation and its relation with rhythm outcome

Aims

This study investigated the possible association between hs-CRP as well as hs-CRP changes and rhythm outcome after AF catheter ablation.

Methods

We studied 68 consecutive patients with AF undergoing catheter ablation. hs-CRP levels were measured using commercially available assays before and 6 months after catheter ablation. Serial 7-day Holter ECGs were used to detect AF recurrences.

Results

Early AF recurrence (ERAF, within one week) was observed in 38%, while late AF recurrence (LRAF, between 3 and 6 months) occurred in 18% of the patients. None of the baseline clinical or echocardiographic variables was predictive of ERAF or LRAF. Baseline hs-CRP measured 2.07±1.1 µg/ml and was not associated with ERAF and LRAF. At 6 months, hs-CRP levels were comparable with baseline values (2.14±1.19 µg/ml, p = 0.409) and were also not related with LRAF. However, patients with LRAF showed an hs-CRP increase from 2.03±0.61 to 2.62±1.52 µg/ml (p = 0.028). Patients with an hs-CRP change in the upper tertile (>0.2 µg/ml) had LRAF in 32% as opposed to 11% (p = 0.042) in patients in the lower (<−0.3 µg/ml) or intermediate (−0.3–0.2 µg/ml) tertile.

Conclusions

Changes in hs-CRP but not baseline hs-CRP are associated with rhythm outcome after AF catheter ablation. This finding points to a link between an inflammatory response and AF recurrence in this setting.