A 3-year continuous record of nitrogen trace gas fluxes from untreated and limed soil of a N-saturated spruce and beech forest ecosystem in Germany: 2. NO and NO₂ fluxes

For 3 years we followed the complete annual cycles of NO and NO$_{2}$ flux rates from soil of a spruce control site, a limed spruce site, and a beech site at the Höglwald Forest, Bavaria, Germany, with high temporal resolution in order to gain detailed information about (1) the impacts of forest type, liming, and atmospheric N input by wet deposition on the magnitude of NO and NO$_{2}$ flux rates and (2) the microbial processes involved in NO production and emission. In addition to identification of seasonal variations of flux rates the huge database allowed calculation of annual mean NO and NO$_{2}$ fluxes with high accuracy and identification of interannual variations of fluxes. The long-term annual mean NO$_{X}$ emission was 61.7 $\mu$g NO$_{X}$ N m$^{-2}$ h$^{-1}$ for the spruce control site, 17.3 $\mu$g NO$_{X}$ N m$^{-^2}$ h${^-1}$ for the limed spruce site, and 4.0 $\mu$g NO$_{X}$ N m$^{-2}$ h$^{-1}$ for the beech site. These extremely high soil NO$_{X}$ emissions from a temperate forest most likely reflect the status of N saturation of the Höglwald Forest as a consequence of year-long heavy atmospheric N input. Multiple regression analyses revealed the following sequence of importance of environmental factors on NO flux: soil temperature to waterfilled pore space to soil NO$^{-}_{3}$ concentrations to soil NH$^{+}_{4}$ concentrations. Nitrification was the dominating biotic modulator of NO emission at all sites: $>$60% of the variation of NO emission rates were associated with variations of net nitrification rates. There was a strong positive correlation between amount of in situ N input by wet deposition and magnitude of in situ NO flux rates. Approximately 15% and 7% of the actual N input was lost as NO from the soil stocked with spruce and beech, respectively. Liming resulted in 49% reduction of NO emissions as compared to an unlimed spruce control site. The results indicate that the reduction in NO emission was due to an increase in NO consumption within the limed soil. In contrast to NO flux, NO$_{2}$ flux was modulated by physico-chemical rather than biological factors. Using the data of this study, we estimate that the contribution of N-affected temperate coniferous and deciduous forests to the global NO$_{X}$ release is 0.3 Tg NO$_{X}$ N yr$^{-1}$

The impact of surgical delay on resectability of colorectal cancer: An international prospective cohort study

AIM: The SARS-CoV-2 pandemic has provided a unique opportunity to explore the impact of surgical delays on cancer resectability. This study aimed to compare resectability for colorectal cancer patients undergoing delayed versus non-delayed surgery. METHODS: This was an international prospective cohort study of consecutive colorectal cancer patients with a decision for curative surgery (January-April 2020). Surgical delay was defined as an operation taking place more than 4 weeks after treatment decision, in a patient who did not receive neoadjuvant therapy. A subgroup analysis explored the effects of delay in elective patients only. The impact of longer delays was explored in a sensitivity analysis. The primary outcome was complete resection, defined as curative resection with an R0 margin. RESULTS: Overall, 5453 patients from 304 hospitals in 47 countries were included, of whom 6.6% (358/5453) did not receive their planned operation. Of the 4304 operated patients without neoadjuvant therapy, 40.5% (1744/4304) were delayed beyond 4 weeks. Delayed patients were more likely to be older, men, more comorbid, have higher body mass index and have rectal cancer and early stage disease. Delayed patients had higher unadjusted rates of complete resection (93.7% vs. 91.9%, P = 0.032) and lower rates of emergency surgery (4.5% vs. 22.5%, P < 0.001). After adjustment, delay was not associated with a lower rate of complete resection (OR 1.18, 95% CI 0.90-1.55, P = 0.224), which was consistent in elective patients only (OR 0.94, 95% CI 0.69-1.27, P = 0.672). Longer delays were not associated with poorer outcomes. CONCLUSION: One in 15 colorectal cancer patients did not receive their planned operation during the first wave of COVID-19. Surgical delay did not appear to compromise resectability, raising the hypothesis that any reduction in long-term survival attributable to delays is likely to be due to micro-metastatic disease

Disease and carrier isolates of Neisseria meningitidis cause G1 cell cycle arrest in human epithelial cells

Zahlreiche humanpathogene bakterielle Erreger können ihre Fähigkeit zur Kolonisation epithelialer Barrieren optimieren, indem sie mit dem Zellzyklus der infizierten Wirtszelle in Wechselwirkung treten und so die Abschilferung und Erneuerung des Epithels verzögern. Die hierbei wirksamen bakteriellen Effektoren sind als „Cyclomoduline“ bekannt und gelten als neue Klasse bakterieller Pathogenitätsfaktoren. Ziel der vorliegenden Promotionsarbeit war es zu untersuchen, ob durch die Infektion menschlicher pharyngealer Epithelzellen mit N. meningitidis der Zellzyklus der Wirtszelle beeinflusst wird. Mit zwei verschiedenen Untersuchungsmethoden konnte übereinstimmend gezeigt werden, dass die Infektion der Epithelzelllinie Detroit 562 mit verschiedenen Meningokokkenisolaten zu einer signifikanten Akkumulation von Epithelzellen in der G1-Phase führte. Dieser Effekt wurde sowohl von pathogenen Meningokokkenstämmen als auch von Trägerstämmen ausgelöst, jedoch nur durch Isolate, die fähig zur Adhärenz und zur Invasion in die Epithelzelle waren. Durch Hitzebehandlung der Bakterien konnte der Zellzyklusarrest vollständig aufgehoben werden. Ebenso konnte der Effekt durch Inkubation der Epithelzellen mit bakteriellen Kulturüberständen und durch Infektion der Zellen mit E. coli-Stämmen, welche die Meningokokkenadhäsine Opa und Opc überexprimieren, nicht ausgelöst werden. Es konnte weiterhin nachgewiesen werden, dass die Infektion mit N. meningitidis in der Zielzelle zu einer signifikant gesteigerten Expression des CDK-Inhibitors p21WAF1/Cip1 führte, begleitet von einer vermehrten Lokalisation im Zellkern. Auch zeigte sich eine veränderte Proteinexpression der für die G1-Phase relevanten Cycline D und E. Diese scheint sich erst posttranslational zu ereignen, da die unterschiedliche Expression auf mRNA-Ebene nicht festgestellt werden konnte. Zusammenfassend konnte dargestellt werden, dass die Infektion von Pharynxepithelzellen mit lebenden, zur Adhärenz und Invasion fähigen Meningokokkenstämmen in der menschlichen Zielzelle einen Zellzyklusarrest in der G1-Phase verursacht, vermutlich durch veränderte Expression der Zellzyklusregulatoren p21WAF1/Cip1, Cyclin D und Cyclin E. Möglicherweise stellt die Induktion dieses Zellzyklusarrestes einen wichtigen Schritt in der Pathogenese der bakteriellen Kolonisation des oberen Atemwegsepithels durch N. meningitidis dar.Several microbial pathogens have developed mechanisms to modulate host cell cycle progression in order to improve bacterial colonization of epithelial barriers. The required bacterial effectors were summarized as “cyclomodulins” and have been proposed to be a new class of virulence factors. The objective of this doctoral research study was to analyze the capability of N. meningitidis to interfere with the cell cycle progression in human pharyngeal epithelial cells. Using two different methods for cell cycle analysis, we show that infection of the human pharyngeal epithelial cell line Detroit 562 with different meningococcal isolates induces an arrest of epithelial host cells in the G1 phase. This effect was caused by infection with both pathogenic isolates and carriage isolates, but only by strains able to adhere to and to invade into the host cells. Heat-inactivation of the bacteria prior to infection completely prevented the cell cycle arrest. Moreover treatment of epithelial cells with bacterial supernatants, as well as infection with E. coli strains expressing neisserial adhesins Opa and Opc did not induce the cell cycle arrest. We further demonstrate that infection of Detroit 562 cells with N. meningitidis leads to a significantly increased expression of the CDK-inhibitor p21WAF1/Cip1 in the host cell, as well as its increased nuclear localization. The protein expression of cyclin D and E, which are relevant for progression through the G1 phase, were altered by bacterial infection, too. This effect is most likely induced by posttranslational modification, since bacterial infection did not affect Cyclin D and E mRNA levels. In conclusion, we demonstrate that infection of human pharyngeal epithelial cells with different isolates of N. meningitidis arrests the host cells at the G1 phase, most likely by affecting the expression of the cell cycle regulators p21WAF1/Cip1, cyclin D and Cyclin E. Potentially, induction this cell cycle arrest is an important step in the pathogenesis of meningococcal colonization and further infection

Preferential use of root litter compared to leaf litter by beech seedlings and soil microorganisms

International audienceBackground and aims Litter decomposition is regulated by e. g. substrate quality and environmental factors, particularly water availability. The partitioning of nutrients released from litter between vegetation and soil microorganisms may, therefore, be affected by changing climate. This study aimed to elucidate the impact of litter type and drought on the fate of litter-derived N in beech seedlings and soil microbes. Methods We quantified N-15 recovery rates in plant and soil N pools by adding N-15-labelled leaf and/or root litter under controlled conditions. Results Root litter was favoured over leaf litter for N acquisition by beech seedlings and soil microorganisms. Drought reduced N-15 recovery from litter in seedlings thereby affecting root N nutrition. N-15 accumulated in seedlings in different sinks depending on litter type. Conclusions Root turnover appears to influence (a) N availability in the soil for plants and soil microbes and (b) N acquisition and retention despite a presumably extremely dynamic turnover of microbial biomass. Compared to soil microorganisms, beech seedlings represent a very minor short-term N sink, despite a potentially high N residence time. Furthermore, soil microbes constitute a significant N pool that can be released in the long term and, thus, may become available for N nutrition of plants

S06.04 -2: TERENO – SoilCAN a lysimeter-network in Germany to study the effect of land use and climate change

TERENO (TERrestrial ENvironmental Observatories) aims to collect and provide long-term observation data of the hydrosphere, biosphere, pedosphere, lower atmosphere, and anthroposphere across multiple spatial and temporal gradients. Based on the TERENO infrastructure, the lysimeter-network SoilCan a long-term large-scale experiment to study the effects of land use changes of terrestrial systems caused by Global Change, has been implemented and represents one of the key research infrastructures for pedological research in TERENO. Main objectives are the terrestrial hydrology, the N-/C-cycle and the biodiversity. In particular, the analysis of changes in water and matter fluxes in the soil-plant-atmosphere system is in the focus of SoilCan. The gained high-quality data will be used for the development and calibration of computer models in combination with remote sensing. The SoilCan network consists of 126 fully automated lysimeter systems that were installed at 13 highly equipped experimental field sites within the TERENO-observatories and the relevant status variables of each ecosystem are monitored (e.g. climate, hydrology, biosphere-atmosphere exchange, biodiversity, etc.). Lysimeters were either left at their sampling site, transplanted inside the observatory of origin, or moved within or between the four different observatories. The translocation of lysimeters was performed along existing temperature and rainfall gradients in order to simulate climate change. The lysimeters are currently cultivated as grassland or arable land with a standardized crop rotation of winter wheat – pea - winter barley - winter canola. The presentation will comprise the results and experience of 18 months of lysimeter networking and will give an outlook on future work