Divergent growth of Norway spruce on Babia Góra Mountain in the western Carpathians

Growth divergence – i.e. the expression of divergent growth trends of neighboring trees – has certain implications for dendrochronological research, for instance in the context of climate reconstructions but also in terms of estimating net ecosystem productivity. Thus, understanding the underlying mechanisms is essential to extend our fundamental dendroecological knowledge. In this context, the Picea genus plays an important role since several of its species were reported to exhibit growth divergence. Here, we investigate a well sampled Norway spruce (Picea abies (L.) Karst) data set for growth divergence comprising ring-width and Blue Intensity measurements from seven sites on Babia Góra Mountain, at the border between Poland and Slovakia. By means of Principal Component Gradient Analysis, inter-series correlations, and climate growth relationships, we are able to show that I) Norway spruce on Babia Góra expressed growth divergence since the 1970s, II) the definition of groups increased the strength of population signals and the stability of climate-growth relationships, and III) Blue Intensity appeared as a more robust proxy for environmental conditions. We discuss soil heterogeneity, genetics, and air pollution as possible underlying mechanisms, thereby indicating further research avenues to obtain a better understanding of growth divergence.     

Eutrophication as an impact category

State of the art and research needs for the impact category eutrophication are discussed. Eutrophication is a difficult impact category because it includes emissions to both air and water — both subject to different environmental mechanisms — as well as impacts occurring in different types of terrestrial and aquatic ecosystems. The possible fate processes are complex and include transportation between different ecosystems. In some recent approaches, transportation modelling of air emissions has been included. However, in general, the used characterisation methods do not integrate fate modelling, which is a limitation. The definition of the impact indicator needs further research, too. The inclusion of other nutrients than those typically considered should also be investigated.     

In Vivo Microbial Coevolution Favors Host Protection and Plastic Downregulation of Immunity

Microbiota can protect their hosts from infection. The short timescales in which microbes can evolve presents the possibility that “protective microbes” can take-over from the immune system of longer-lived hosts in the coevolutionary race against pathogens. Here, we found that coevolution between a protective bacterium (Enterococcus faecalis) and a virulent pathogen (Staphylococcus aureus) within an animal population (Caenorhabditis elegans) resulted in more disease suppression than when the protective bacterium adapted to uninfected hosts. At the same time, more protective E. faecalis populations became costlier to harbor and altered the expression of 134 host genes. Many of these genes appear to be related to the mechanism of protection, reactive oxygen species production. Crucially, more protective E. faecalis populations downregulated a key immune gene, , known to be effective against S. aureus infection. These results suggest that a microbial line of defense is favored by microbial coevolution and may cause hosts to plastically divest of their own immunity.     

Prelude to oral microbes and chronic diseases: past,present and future

Associations between oral and systemic health are ancient. Oral opportunistic bacteria, particularly, Porphyromonas gingivalis and Fusobacterium nucleatum, have recently been deviated from their traditional roles as periodontal pathogens and arguably ascended to central players based on their participations in complex co-dependent mechanisms of diverse systemic chronic diseases risk and pathogenesis, including cancers, rheumatoid-arthritis, and diabetes.     

The influence of moisture on microbial transport, survival and 2,4-D biodegradation with a genetically marked Burkholderia cepacia in unsaturated soil columns

The influence of moisture on the survival, movement anddegradation activity of a 2,4-D degrading bacterium,Burkholderia cepacia strain BRI6001L, geneticallyengineered to contain bioluminescent and lactoseutilization genes, was studied in unsaturated soil columns.The distance traveled by BRI6001L was dependent on theclay content of the soil, higher clay contents beingresponsible for higher filtration coefficients. Long termsurvival, in excess of one year, was attributed to strainBRI6001L's ability to survive dry conditions. Changes inthe 2,4-D biodegradation rate showed a better correlationwith the BRI6001L population density than with the totalviable bacterial population. At moisture levels betweenfield capacity and 40% moisture (– 33 kPa to –100 kPa)2,4-D degradation was attributed mainly to BRI6001L. Atmoisture levels between 6 and 15%, 2,4-D disappearancewas attributed to the indigenous microbial population,with no degradation occurring at moisture levels below6%. Returning the moisture to above 40% led to anincrease of 4 orders of magnitude in the BRI6001Lpopulation density and to a 10-fold increase in the 2,4-Ddegradation rate. The ability to monitor a specificmicrobial population using reporter genes hasdemonstrated the importance of controlling moisturelevels for maximizing biodegradation rates in unsaturatedsoil environments.