Population-Specific Responses to Interspecific Competition in the Gut Microbiota of Two Atlantic Salmon (Salmo salar) Populations

The gut microbial community in vertebrates plays a role in nutrient digestion and absorption, development of intestine and immune systems, resistance to infection, regulation of bone mass and even host behavior and can thus impact host fitness. Atlantic salmon (Salmo salar) reintroduction efforts into Lake Ontario, Canada, have been unsuccessful, likely due to competition with non-native salmonids. In this study, we explored interspecific competition effects on the gut microbiota of two Atlantic salmon populations (LaHave and Sebago) resulting from four non-native salmonids. After 10 months of rearing in semi-natural stream tanks under six interspecific competition treatments, we characterized the gut microbiota of 178 Atlantic salmon by parallel sequencing the 16S rRNA gene. We found 3978 bacterial OTUs across all samples. Microbiota alpha diversity and abundance of 27 OTUs significantly differed between the two populations. Interspecific competition reduced relative abundance of potential beneficial bacteria (six genera of lactic acid bacteria) as well as 13 OTUs, but only in the LaHave population, indicating population-specific competition effects. The pattern of gut microbiota response to interspecific competition may reflect local adaptation of the host-microbiota interactions and can be used to select candidate populations for improved species reintroduction success

Determinants of multiple central-place territory use in wild young-of-the-year Atlantic salmon (Salmo salar)

Patterns of space use provide key insights into how animals exploit local resources and are linked to both the fitness and distribution of individuals. We studied territory size, mobility, and foraging behavior of young-of-the-year Atlantic salmon Salmo salar in relation to several key environmental factors in Catamaran Brook, New Brunswick, Canada. The 50 study fish were all multiple central-place foragers (i.e., alternated among several sit-and-wait foraging stations) and showed great variability in territory size and the total distance traveled within the territories. Territory size increased with the mean distance traveled between consecutive foraging stations, the number of stations visited, and the mean foraging radius. Fish also varied greatly in how much of the total travel distance was associated with foraging at a station (14.8–91.8%) versus switching among stations (4.6–84.3%). As predicted, fish in slow-flowing waters, where drifting prey were scarce, used larger multiple central-place territories than individuals in faster, more productive waters. Interestingly, however, the most mobile fish did not inhabit slow-running waters as predicted but were found at intermediate (optimal) water current velocities. Hence, our study suggests that among some multiple central-place foragers, increased mobility may not only serve to increase prey encounter rate but may reflect an attempt to patrol territories in favorable habitats. Further studies are needed to determine the generality and the ultimate benefits of multiple central-place space use among stream-dwelling fish and other animals

How and why do subcontractors experience different safety on high-risk work sites?

In high-risk industries such as construction, mining and energy, subcontractors play an increasingly significant role. A typical arrangement is for the site owner to hire a principal contractor who in turn hires multiple subcontractors. This means that multiple subcontractors from multiple companies can be working on the same site at the same time. There is evidence that the use of subcontractors is not only increasing, but that the accident rates for subcontractor employees are higher than those of operator/site owner employees. Existing research on subcontractors, which focuses on the role of the prime contractor in selecting and managing subcontractors, fails to explain why subcontractors continue to experience higher rates of serious injury even where subcontractor management systems are in place. The purpose of this paper is to understand how and why employees of subcontractors’ experience safety differently from employees of principal contractors. The paper does so by extensively reviewing the applicable literature and reporting on a cross-industry focus group study.Full Tex

Brain Metastases Cell Partners and Tumor Microenvironment

The microenvironment has emerged as a promising source of novel therapeutic applications in experimental models of brain metastasis. Our limited understanding of the complex brain ecosystem transformed by the presence of cancer cells includes key cell types that either promote or limit local progression of metastatic cells. Identification of the molecular networks regulating the crosstalk between cancer cells and the microenvironment but also within different brain resident and non-resident cell types surrounding the tumor is crucial to decipher the biology of colonization and subsequently to target key nodes with innovative and effective therapies.Research in the Brain Metastasis Group is supported by MINECO grants MINECO-Retos SAF2017-89643-R (M.V.), Bristol-Myers Squibb-Melanoma Research Alliance Young Investigator Award 2017 (498103) (M.V.), Beug Foundation’s Prize for Metastasis Research 2017 (M.V.), Fundación Ramón Areces (CIVP19S8163) (M.V.), Worldwide Cancer Research (19-0177) (M.V.), H2020-FETOPEN (828972) (M.V.), Clinic and Laboratory Integration Program CRI Award 2018 (54545) (M.V.), AECC Coordinated Translational Groups 2017 (GCTRA16015SEOA) (M.V.), LAB AECC 2019 (LABAE19002VALI) (M.V.), AECC Postdoctoral Grant (POSTD19016PRIE) (N.P.), La Caixa INPhINIT Fellowship (100010434) (P.G-G.), MINECO-Severo Ochoa PhD Fellowship (BES-2017-081995) (L.A-E.). M.V. is a Ramón y Cajal Investigator (RYC-2013-13365) and EMBO YIP (4053).N