Threats and knowledge gaps for ecosystem services provided by kelp forests: a northeast Atlantic perspective

Kelp forests along temperate and polar coastlines represent some of most diverse and productive habitats on the Earth. Here, we synthesize information from >60 years of research on the structure and functioning of kelp forest habitats in European waters, with particular emphasis on the coasts of UK and Ireland, which represents an important biogeographic transition zone that is subjected to multiple threats and stressors. We collated existing data on kelp distribution and abundance and reanalyzed these data to describe the structure of kelp forests along a spatial gradient spanning more than 10° of latitude. We then examined ecological goods and services provided by kelp forests, including elevated secondary production, nutrient cycling, energy capture and flow, coastal defense, direct applications, and biodiversity repositories, before discussing current and future threats posed to kelp forests and identifying key knowledge gaps. Recent evidence unequivocally demonstrates that the structure of kelp forests in the NE Atlantic is changing in response to climate‐ and non‐climate‐related stressors, which will have major implications for the structure and functioning of coastal ecosystems. However, kelp‐dominated habitats along much of the NE Atlantic coastline have been chronically understudied over recent decades in comparison with other regions such as Australasia and North America. The paucity of field‐based research currently impedes our ability to conserve and manage these important ecosystems. Targeted observational and experimental research conducted over large spatial and temporal scales is urgently needed to address these knowledge gaps.     

Thyroid hormones in the elderly sick: "T4 euthyroidism".

Thyroid function and serum levels of triiodothyronine (T3) and thyroxine (T4) were investigated in 79 euthyroid geriatric patients. Of the 59 inpatients and 20 outpatients 35 (59%) and 2, respectively, had low T3 levels. In contrast, 7 (12%) and 6 (30%), respectively, had raised T4 levels. Two further patients were excluded from the study because of raised levels of thyroid-stimulating hormone. Thyroxine-binding globulin was greatly increased in both groups of patients, but low serum albumin levels were present in 31 (39%). Despite these changes free T3 and T4 indices closely followed total T3 and T4 levels. The difference between the two groups of patients did not correlate with body weight, diagnostic categories, age, drug treatment, or duration of stay in hospital.     

Historical comparisons reveal multiple drivers of decadal change of an ecosystem engineer at the range edge

Biogenic reefs are important for habitat provision and coastal protection. Long‐term datasets on the distribution and abundance of Sabellaria alveolata (L.) are available from Britain. The aim of this study was to combine historical records and contemporary data to (1) describe spatiotemporal variation in winter temperatures, (2) document short‐term and long‐term changes in the distribution and abundance of S. alveolata and discuss these changes in relation to extreme weather events and recent warming, and (3) assess the potential for artificial coastal defense structures to function as habitat for S. alveolata. A semi‐quantitative abundance scale (ACFOR) was used to compare broadscale, long‐term and interannual abundance of S. alveolata near its range edge in NW Britain. S. alveolata disappeared from the North Wales and Wirral coastlines where it had been abundant prior to the cold winter of 1962/1963. Population declines were also observed following the recent cold winters of 2009/2010 and 2010/2011. Extensive surveys in 2004 and 2012 revealed that S. alveolata had recolonized locations from which it had previously disappeared. Furthermore, it had increased in abundance at many locations, possibly in response to recent warming. S. alveolata was recorded on the majority of artificial coastal defense structures surveyed, suggesting that the proliferation of artificial coastal defense structures along this stretch of coastline may have enabled S. alveolata to spread across stretches of unsuitable natural habitat. Long‐term and broadscale contextual monitoring is essential for monitoring responses of organisms to climate change. Historical data and gray literature can be invaluable sources of information. Our results support the theory that Lusitanian species are responding positively to climate warming but also that short‐term extreme weather events can have potentially devastating widespread and lasting effects on organisms. Furthermore, the proliferation of coastal defense structures has implications for phylogeography, population genetics, and connectivity of coastal populations.     

Trichuris muris Infection: A Model of Type 2 Immunity and Inflammation in the Gut

Trichuris muris is a natural pathogen of mice and is biologically and antigenically similar to species of Trichuris that infect humans and livestock¹. Infective eggs are given by oral gavage, hatch in the distal small intestine, invade the intestinal epithelial cells (IECs) that line the crypts of the cecum and proximal colon and upon maturation the worms release eggs into the environment¹. This model is a powerful tool to examine factors that control CD4⁺ T helper (Th) cell activation as well as changes in the intestinal epithelium. The immune response that occurs in resistant inbred strains, such as C57BL/6 and BALB/c, is characterized by Th2 polarized cytokines (IL-4, IL-5 and IL-13) and expulsion of worms while Th1-associated cytokines (IL-12, IL-18, IFN-γ) promote chronic infections in genetically susceptible AKR/J mice^2-6. Th2 cytokines promote physiological changes in the intestinal microenvironment including rapid turnover of IECs, goblet cell differentiation, recruitment and changes in epithelial permeability and smooth muscle contraction, all of which have been implicated in worm expulsion^7-15. Here we detail a protocol for propagating Trichuris muris eggs which can be used in subsequent experiments. We also provide a sample experimental harvest with suggestions for post-infection analysis. Overall, this protocol will provide researchers with the basic tools to perform a Trichuris muris mouse infection model which can be used to address questions pertaining to Th proclivity in the gastrointestinal tract as well as immune effector functions of IECs.     

The Platform Protein Is Essential for Type IV Pilus Biogenesis

A systematic genetic analysis was performed to identify the inner membrane proteins essential for type IV pilus (T4P) expression in Pseudomonas aeruginosa. By inactivating the retraction aspect of pilus function, genes essential for T4P assembly were discriminated. In contrast to previous studies in the T4P system of Neisseria spp., we found that components of the inner membrane subcomplex consisting of PilMNOP were not essential for surface pilus expression, whereas the highly conserved inner membrane protein PilC was essential. Here, we present data that PilC may coordinate the activity of cytoplasmic polymerization (PilB) and depolymerization (PilT) ATPases via their interactions with its two cytoplasmic domains. Using in vitro co-affinity purification, we show that PilB interacts with the N-terminal cytoplasmic domain of PilC. We hypothesized that PilT similarly interacts with the PilC C-terminal cytoplasmic domain. Overexpression of that domain in the wild-type protein reduced twitching motility by ∼50% compared with the vector control. Site-directed mutagenesis of conserved T4P-specific residues in the PilC C-terminal domain yielded mutant proteins that supported wild-type pilus assembly but had a reduced capacity to support twitching motility, suggesting impairment of putative PilC-PilT interactions. Taken together, our results show that PilC is an essential inner membrane component of the T4P system, controlling both pilus assembly and disassembly.