Phosphorus alleviation of nitrogen‐suppressed methane sink in global grasslands

Grassland ecosystems account for more than 10% of the global CH₄ sink in soils. A 4‐year field experiment found that addition of P alone did not affect CH₄ uptake and experimental addition of N alone significantly suppressed CH₄ uptake, whereas concurrent N and P additions suppressed CH₄ uptake to a lesser degree. A meta‐analysis including 382 data points in global grasslands corroborated these findings. Global extrapolation with an empirical modelling approach estimated that contemporary N addition suppresses CH₄ sink in global grassland by 11.4% and concurrent N and P deposition alleviates this suppression to 5.8%. The P alleviation of N‐suppressed CH₄ sink is primarily attributed to substrate competition, defined as the competition between ammonium and CH₄ for the methane mono‐oxygenase enzyme. The N and P impacts on CH₄ uptake indicate that projected increases in N and P depositions might substantially affect CH₄ uptake and alter the global CH₄ cycle.     

Microbial carbon limitation: The need for integrating microorganisms into our understanding of ecosystem carbon cycling

Numerous studies have demonstrated that fertilization with nutrients such as nitrogen, phosphorus, and potassium increases plant productivity in both natural and managed ecosystems, demonstrating that primary productivity is nutrient limited in most terrestrial ecosystems. In contrast, it has been demonstrated that heterotrophic microbial communities in soil are primarily limited by organic carbon or energy. While this concept of contrasting limitations, that is, microbial carbon and plant nutrient limitation, is based on strong evidence that we review in this paper, it is often ignored in discussions of ecosystem response to global environment changes. The plant‐centric perspective has equated plant nutrient limitations with those of whole ecosystems, thereby ignoring the important role of the heterotrophs responsible for soil decomposition in driving ecosystem carbon storage. To truly integrate carbon and nutrient cycles in ecosystem science, we must account for the fact that while plant productivity may be nutrient limited, the secondary productivity by heterotrophic communities is inherently carbon limited. Ecosystem carbon cycling integrates the independent physiological responses of its individual components, as well as tightly coupled exchanges between autotrophs and heterotrophs. To the extent that the interacting autotrophic and heterotrophic processes are controlled by organisms that are limited by nutrient versus carbon accessibility, respectively, we propose that ecosystems by definition cannot be ‘limited’ by nutrients or carbon alone. Here, we outline how models aimed at predicting non‐steady state ecosystem responses over time can benefit from dissecting ecosystems into the organismal components and their inherent limitations to better represent plant–microbe interactions in coupled carbon and nutrient models.     

Dietary generalism accelerates arrival and persistence of coral‐reef fishes in their novel ranges under climate change

Climate change is redistributing marine and terrestrial species globally. Life‐history traits mediate the ability of species to cope with novel environmental conditions, and can be used to gauge the potential redistribution of taxa facing the challenges of a changing climate. However, it is unclear whether the same traits are important across different stages of range shifts (arrival, population increase, persistence). To test which life‐history traits most mediate the process of range extension, we used a 16‐year dataset of 35 range‐extending coral‐reef fish species and quantified the importance of various traits on the arrival time (earliness) and degree of persistence (prevalence and patchiness) at higher latitudes. We show that traits predisposing species to shift their range more rapidly (large body size, broad latitudinal range, long dispersal duration) did not drive the early stages of redistribution. Instead, we found that as diet breadth increased, the initial arrival and establishment (prevalence and patchiness) of climate migrant species in temperate locations occurred earlier. While the initial incursion of range‐shifting species depends on traits associated with dispersal potential, subsequent establishment hinges more on a species’ ability to exploit novel food resources locally. These results highlight that generalist species that can best adapt to novel food sources might be most successful in a future ocean.     

Exploring Beneficial/Virulence Properties of Two Dairy-Related Strains of Streptococcus infantarius subsp. infantarius

The genus Streptococcus includes various species, remarkably different in their behavior, applications, virulence, and safety. Taxonomically Streptococcus infantarius subsp. infantarius belonging to the Streptococcus bovis group, which includes several pathogen species, however, has been found as predominant species in some African dairy products that are widely consumed and considered to be safe. Streptococcus infantarius subsp. infantarius’ safety may be questioned due to the association of this species with clinical cases. In this study, isolates from dairy origin were selected based on their bacteriocinogenic potential and differentiated by their RAPD-PCR profiles. Two strains were identified by 16S rRNA sequencing as St. infantarius subsp. infantarius and investigated regarding their potential beneficial properties and factors related to virulence and safety. A series of in vitro tests included properties related to survival in the gastrointestinal tract and beneficial intestinal activities. Production of bacteriocin/s, detection of related genes, and partial characterization of expressed antimicrobial protein were evaluated. Genes related to folate biosynthesis were detected in both studied strains. Evaluation of physiological tests related to strains virulence, adhesion, and resistance to antibiotics and detections of virulence and biogenic amines production-related genes were also investigated. Taking in consideration all the aspects of the specific nature of St. infantarius subsp. infantarius K1–4 and K5–1 (beneficial properties and virulence characteristics), both strains cannot be considered safe for human or other animals application, even though they have been isolated from dairy products. This study is highlighting the importance of evaluation for presence of potential virulence factors in newly characterized strains in order to be confident in their safety.

     

Standardized Aronia melanocarpa extract regulates redox status in patients receiving hemodialysis with anemia

Molecular and Cellular Biochemistry - The aim of our study was to investigate the effects of one-month consumption of polyphenol-rich standardized Aronia melanocarpa extract (SAE) on redox status...     

Novel species interactions and environmental conditions reduce foraging competency at the temperate range edge of a range-extending coral reef fish

Poleward range extensions of coral reef species can reshuffle temperate communities by generating competitive interactions that did not exist previously. However, novel environmental conditions and locally adapted native temperate species may slow tropical invasions by reducing the ability of invaders to access local resources (e.g. food and shelter). We test this hypothesis on wild marine fish in a climate warming hotspot using a field experiment encompassing artificial prey release. We evaluated seven behaviours associated with foraging and aggressive interactions in a common range-extending coral reef fish (Abudefduf vaigiensis) and a co-shoaling temperate fish (Microcanthus strigatus) along a latitudinal temperature gradient (730 km) in SE Australia. We found that the coral reef fish had reduced foraging performance (i.e. slower prey perception, slower prey inspection, decreased prey intake, increased distance to prey) in their novel temperate range than in their subtropical range. Furthermore, higher abundance of temperate fishes was associated with increased retreat behaviour by coral reef fish (i.e. withdrawal from foraging on released prey), independent of latitude. Where their ranges overlapped, temperate fish showed higher foraging and aggression than coral reef fish. Our findings suggest that lower foraging performance of tropical fish at their leading range edge is driven by the combined effect of environmental factors (e.g. lower seawater temperature and/or unfamiliarity with novel conditions in their extended temperate ranges) and biological factors (e.g. increased abundance and larger body sizes of local temperate fishes). Whilst a future increase in ocean warming is expected to alleviate current foraging limitations in coral reef fishes at leading range edges, under current warming native temperate fishes at their trailing edges appear able to slow the range extension of coral reef fishes into temperate ecosystems by limiting their access to resources.

     

From Mesolithic hunters to Iron Age herders: a unique record of woodland use from eastern central Europe (Czech Republic)

Vegetation History and Archaeobotany - In a continuous, perfectly stratified sedimentary sequence which was discovered under a large sandstone overhang in northern Bohemia, Czech Republic, we...