Stoichiometric distribution models: ecological stoichiometry at the landscape extent.

Human activities are altering the fundamental geography of biogeochemicals. Yet we lack an understanding of how the spatial patterns in organismal stoichiometry affect biogeochemical processes and the tools to predict the impacts of global changes on biogeochemical processes. In this contribution we develop stoichiometric distribution models (StDMs), which allow us to map spatial structure in resource elemental composition across a landscape and evaluate spatial responses of consumers. We parameterise StDMs for a consumer-resource (moose-white birch) system and demonstrate that we can develop predictive models of resource stoichiometry across a landscape and that such models could improve our predictions of consumer space use. With results from our study system application, we argue that explicit consideration of the spatial patterns in organismal elemental composition may uncover emergent individual, population, community and ecosystem properties that are not revealed at the local extents routinely used in ecological stoichiometry. We discuss perspectives for further developments and application of StDMs to advance three emerging frameworks for spatial ecosystem ecology in an era of global change; meta-ecosystem theory, macroecological stoichiometry and remotely sensed biogeochemistry. Progress on these emerging frameworks will allow for the integration of ecological stoichiometry and individual space use and fitness.

Quantification and characterization of plastics in near-shore surface waters of Atlantic Canada.

Plastics are a ubiquitous pollutant in the marine environment. Despite growing concerns, quantitative and qualitative data on microplastics in aquatic and marine environments of Atlantic Canada is just emerging. Surface water plastics were measured and categorized by morphology (thread, microfibre, fragment, foam, film, pellet, and microbead) in two locations in Nova Scotia and one in Newfoundland and Labrador, Canada. All sites within the three locations contained plastic with an average abundance of 9669 items/km2. Most plastics (68 %) were sized as microplastics (0.425-5 mm), and plastic fragments were the most common morphological type. Polyethylene accounted for a third (30 %) of all particles found across all three locations, followed by polypropylene (23 %). Results can inform future research for community-based environmental groups, government, and academia.

Deletion of Yy1 in mouse lung epithelium unveils molecular mechanisms governing pleuropulmonary blastoma pathogenesis.

Pleuropulmonary blastoma (PPB) is a very rare pediatric lung disease. It can progress from abnormal epithelial cysts to an aggressive sarcoma with poor survival. PPB is difficult to diagnose as it can be confounded with other cystic lung disorders, such as congenital pulmonary airway malformation (CPAM). PPB is associated with mutations in DICER1 that perturb the microRNA (miRNA) profile in lung. How DICER1 and miRNAs act during PPB pathogenesis remains unsolved. Lung epithelial deletion of the Yin Yang1 (Yy1) gene in mice causes a phenotype mimicking the cystic form of PPB and affects the expression of key regulators of lung development. Similar changes in expression were observed in PPB but not in CPAM lung biopsies, revealing a distinctive PPB molecular signature. Deregulation of molecules promoting epithelial-mesenchymal transition (EMT) was detected in PPB specimens, suggesting that EMT might participate in tumor progression. Changes in miRNA expression also occurred in PPB lung biopsies. miR-125a-3p, a candidate to regulate YY1 expression and lung branching, was abnormally highly expressed in PPB samples. Together, these findings support the concept that reduced expression of YY1, due to the abnormal miRNA profile resulting from DICER1 mutations, contributes to PPB development via its impact on the expression of key lung developmental genes.This article has an associated First Person interview with the joint first authors of the paper.

Low incidence of plastic ingestion among three fish species significant for human consumption on the island of Newfoundland, Canada.

This study reports the first baselines of plastic ingestion for three fish species that are common commercial and sustenance food fish in Newfoundland. Species collections occurred between 2015 and 2016 for Atlantic cod (Gadus morhua), Atlantic salmon (Salmo salar), and capelin (Mallotus villosus). The frequency of occurrence (%FO) of plastic ingestion for both Atlantic salmon (n = 69) and capelin (n = 350) was 0%. Of the 1010 Atlantic cod individuals collected over two years, 17 individuals had ingested plastics, a %FO of 1.68%. This is the only multi-year investigation of plastic ingestion in Atlantic cod for the Northwest Atlantic, and the first baseline of plastic ingestion in Atlantic salmon and capelin on the island of Newfoundland. Considering the ecological, economic, and cultural importance of these fish species, this study is the beginning of a longitudinal study of plastic ingestion to detect any future changes in contamination levels.

Microplastic sampling with the AVANI trawl compared to two neuston trawls in the Bay of Bengal and South Pacific.

Many typical neuston trawls can only be used during relatively calm sea states and slow tow speeds. During two expeditions to the Bay of Bengal and the eastern South Pacific we investigated whether the new, high-speed AVANI trawl (All-purpose Velocity Accelerated Net Instrument) collects similar amounts and types of microplastics as two established scientific trawl designs, the manta trawl and the DiSalvo neuston net. Using a 335 µm net, the AVANI trawl can collect microplastics from the sea surface at speeds up to 8 knots as it "skis" across the surface, whereas the manta and DiSalvo neuston trawls must be towed slowly in a less turbulent sea state and often represent shorter tow lengths. Generally, the AVANI trawl collected a greater numerical abundance and weight of plastic particles in most size classes and debris types than the manta trawl and DiSalvo neuston net, likely because these trawls only skim the surface layer while the AVANI trawl, moving vertically in a random fashion, collects a "deeper" sample, capturing the few plastics that float slightly lower in the water column. However, the samples did not differ enough that results were significantly affected, suggesting that studies done with these different trawls are comparable. The advantage of the AVANI trawl over traditional research trawls is that it allows for collection on vessels underway at high speeds and during long transits, allowing for a nearly continuous sampling effort over long distances. As local surface currents make sea surface abundance widely heterogeneous, widely spaced short-tow trawls, such as the manta and DiSalvo trawls, can catch or miss hotspots or meso-scale variability of microplastic accumulations, whereas the AVANI trawl, if utilized for back-to-back tows of intermediate distances (5-10 km), can bridge variable wind conditions and debris concentrations potentially reducing variance and provide a greater resolution of spatial distribution.

Mek1Y130C mice recapitulate aspects of human cardio-facio-cutaneous syndrome.

The RAS/MAPK signaling pathway is one of the most investigated pathways, owing to its established role in numerous cellular processes and implication in cancer. Germline mutations in genes encoding members of the RAS/MAPK pathway also cause severe developmental syndromes collectively known as RASopathies. These syndromes share overlapping characteristics, including craniofacial dysmorphology, cardiac malformations, cutaneous abnormalities and developmental delay. Cardio-facio-cutaneous syndrome (CFC) is a rare RASopathy associated with mutations in BRAF, KRAS, MEK1 (MAP2K1) and MEK2 (MAP2K2). MEK1 and MEK2 mutations are found in ∼25% of the CFC patients and the MEK1Y130C substitution is the most common one. However, little is known about the origins and mechanisms responsible for the development of CFC. To our knowledge, no mouse model carrying RASopathy-linked Mek1 or Mek2 gene mutations has been reported. To investigate the molecular and developmental consequences of the Mek1Y130C mutation, we generated a mouse line carrying this mutation. Analysis of mice from a Mek1 allelic series revealed that the Mek1Y130C allele expresses both wild-type and Y130C mutant forms of MEK1. However, despite reduced levels of MEK1 protein and the lower abundance of MEK1 Y130C protein than wild type, Mek1Y130C mutants showed increased ERK (MAPK) protein activation in response to growth factors, supporting a role for MEK1 Y130C in hyperactivation of the RAS/MAPK pathway, leading to CFC. Mek1Y130C mutant mice exhibited pulmonary artery stenosis, cranial dysmorphia and neurological anomalies, including increased numbers of GFAP+ astrocytes and Olig2+ oligodendrocytes in regions of the cerebral cortex. These data indicate that the Mek1Y130C mutation recapitulates major aspects of CFC, providing a new animal model to investigate the physiopathology of this RASopathy. This article has an associated First Person interview with the first author of the paper.