Endoplasmic reticulum (ER) stress is of considerable interest to plant biologists because it occurs in plants subjected to adverse environmental conditions. ER stress responses mitigate the damage ...caused by stress and confer levels of stress tolerance to plants. ER stress is activated by misfolded proteins that accumulate in the ER under adverse environmental conditions. Under these conditions, the demand for protein folding exceeds the capacity of the system, which sets off the unfolded protein response (UPR). Two arms of the UPR signaling pathway have been described in plants: one that involves two ER membrane-associated transcription factors (bZIP17 and bZIP28) and another that involves a dual protein kinase (RNA-splicing factor IRE1) and its target RNA (bZIP60). Under mild or short-term stress conditions, signaling from IRE1 activates autophagy, a cell survival response. But under severe or chronic stress conditions, ER stress can lead to cell death.
Significant attention has focused on the potential for increased shipping activity driven by recently observed declines in Arctic sea ice cover. In this study, we describe the first coupled spatial ...analysis between shipping activity and sea ice using observations in the Canadian Arctic over the 1990–2015 period. Shipping activity is measured by using known ship locations enhanced with a least cost path algorithm to generate ship tracks and quantified by computing total distance traveled in kilometers. Statistically significant increases in shipping activity are observed in the Hudson Strait (150–500 km traveled yr−1), the Beaufort Sea (40–450 km traveled yr−1), Baffin Bay (50–350 km traveled yr−1), and regions in the southern route of the Northwest Passage (50–250 km traveled yr−1). Increases in shipping activity are significantly correlated with reductions in sea ice concentration (Kendall's tau up to −0.6) in regions of the Beaufort Sea, Western Parry Channel, Western Baffin Bay, and Foxe Basin. Changes in multiyear ice‐dominant regions in the Canadian Arctic were found to be more influential on changes to shipping activity compared to seasonal sea ice regions.
Key Points
First observational coupled spatial analysis of the influence of declining sea ice on increasing ship activity in the Canadian Arctic
Shipping activity increases are significantly correlated to declining sea ice in several regions
The presence of multiyear ice seems to influence shipping activity more than seasonal first‐year ice
Declining sea ice area in the Canadian Arctic has gained significant attention with respect to the prospect of increased shipping activities. To investigate relationships between recent declines in ...sea ice area with Arctic maritime activity, trend and correlation analysis was performed on sea ice area data for total, first-year ice (FYI), and multi-year ice (MYI), and on a comprehensive shipping dataset of observed vessel transits through the Vessel Traffic Reporting Arctic Canada Traffic Zone (NORDREG zone) from 1990 to 2012. Links to surface air temperature (SAT) and the satellite derived melt season length were also investigated. Between 1990 and 2012, statistically significant increases in vessel traffic were observed within the NORDREG zone on monthly and annual time-scales coincident with declines in sea ice area (FYI, MYI, and total ice) during the shipping season and on a monthly basis. Similarly, the NORDREG zone is experiencing increased shoulder season shipping activity, alongside an increasing melt season length and warming surface air temperatures (SAT). Despite these trends, only weak correlations between the variables were identified, although a step increase in shipping activity is apparent following the former summer sea ice extent minimum in 2007. Other non-environmental factors have also likely contributed to the observed increase in Arctic shipping activity within the Canadian Arctic, such as tourism demand, community re-supply needs, and resource exploration trends.
The unfolded protein response (UPR) in plants is elicited by endoplasmic reticulum stress, which can be brought about by adverse environmental conditions. The response is mediated by a conserved ...signalling network composed of two branches – one branch involving inositol requiring enzyme1‐ basic leucine zipper60 (IRE1‐bZIP60) signalling pathway and another branch involving the membrane transcription factors, bZIP17 and −28. The UPR has been reported in Chlamydomonas reinhardtii, a unicellular green alga, which lacks some canonical UPR signalling components found in vascular plants, raising the question whether C. reinhardtii uses other means such as oxidative signalling or Regulated IRE1‐Dependent Decay to activate the UPR. In vascular plants, IRE1 splices bZIP60 mRNA in response to endoplasmic reticulum stress by cutting at a site in the RNA that is highly conserved in structure and sequence. Monocots have a single IRE1 gene required for viability in rice, while dicots have two IRE1 genes, IRE1a and ‐b. Brassicas have a third IRE1 gene, IRE1c, which lacks a lumenal domain, but is required in combination with IRE1b for gametogenesis. Vascular and non‐vascular plants upregulate a similar set of genes in response to endoplasmic reticulum stress despite differences in the complexity of their UPR signalling networks.
The Unfolded Protein Response is an evolutionary conserved response to protect plants from adverse environmental conditions. The signaling network for this response has increased in complexity, and the response has taken on greater functions during the course of plant evolution.
The limited availability of consistent, longitudinal data sources for marine traffic in Arctic Canada has presented significant challenges for researchers, policy makers, and planners. Temporally and ...spatially accurate shipping data that reveal historical and current traffic trends are vital to plan safe shipping corridors, develop infrastructure, plan and manage protected areas, and understand the potential environmental and cultural impacts of change, as well as for sovereignty and safety considerations. This study uses a recently developed geospatial database of ship traffic to provide the first synthesized overview of the spatial and temporal variability of different vessel types in Arctic Canada during the 26-year period from 1990 to 2015. This examination shows that, overall, the distance traveled by ships in Arctic Canada nearly tripled (from 364 179 km in 1990 to 918 266 km in 2015), that the largest proportion of ship traffic in the region is from general cargo vessels and government icebreakers (including research ships), and that the fastest growing vessel type by far is pleasure craft (private yachts). Spatial shifts in vessel activity over the last quarter century have favoured areas with active mine sites, as well as the southern route of the Northwest Passage. As a result, some communities, including Baker Lake, Chesterfield Inlet, Pond Inlet, and Cambridge Bay, are experiencing greater increases in ship traffic.
La faible disponibilité de sources de données longitudinales cohérentes pour le trafic maritime de l’Arctique canadien pose d’importants défis aux chercheurs, aux responsables des politiques et aux planificateurs. L’existence de données d’expédition temporelles et spatiales précises qui révèlent les tendances historiques et actuelles du trafic s’avère essentielle pour planifier la sûreté des couloirs de navigation, aménager l’infrastructure, planifier et gérer les zones protégées, comprendre les incidences environnementales et culturelles potentielles découlant du changement et agir en fonction des considérations de souveraineté et de sécurité. Cette étude s’appuie sur une base de données géospatiale du trafic maritime récemment conçue pour fournir la première synthèse de la variabilité spatiale et temporelle de différents types de navires dans l’Arctique canadien au cours de la période de 26 ans allant de 1990 à 2015. L’étude démontre que, globalement, la distance parcourue par les navires dans l’Arctique canadien a presque triplé (passant de 364 179 km en 1990 à 918 266 km en 2015), que les navires de marchandises diverses et les brise-glaces gouvernementaux (y compris les navires de recherche) forment la plus grande partie du trafic maritime dans la région, et que le trafic des bateaux de plaisance (yachts privés) est, de loin, le trafic qui connaît le plus grand essor. Les changements spatiaux sur le plan de l’activité des navires au cours du dernier quart de siècle ont favorisé les zones ayant des sites miniers actifs, ainsi que la route sud du passage du Nord-Ouest. Par conséquent, certaines collectivités, dont celles de Baker Lake, Chesterfield Inlet, Pond Inlet et Cambridge Bay, connaissent une plus forte augmentation de la circulation maritime.
High temperatures causing heat stress disturb cellular homeostasis and impede growth and development in plants. Extensive agricultural losses are attributed to heat stress, often in combination with ...other stresses. Plants have evolved a variety of responses to heat stress to minimize damage and to protect themselves from further stress. A narrow temperature window separates growth from heat stress, and the range of temperatures conferring optimal growth often overlap with those producing heat stress. Heat stress induces a cytoplasmic heat stress response (HSR) in which heat shock transcription factors (HSFs) activate a constellation of genes encoding heat shock proteins (HSPs). Heat stress also induces the endoplasmic reticulum (ER)-localized unfolded protein response (UPR), which activates transcription factors that upregulate a different family of stress response genes. Heat stress also activates hormone responses and alternative RNA splicing, all of which may contribute to thermotolerance. Heat stress is often studied by subjecting plants to step increases in temperatures; however, more recent studies have demonstrated that heat shock responses occur under simulated field conditions in which temperatures are slowly ramped up to more moderate temperatures. Heat stress responses, assessed at a molecular level, could be used as traits for plant breeders to select for thermotolerance.
Ice thickness in the Northwest Passage Haas, Christian; Howell, Stephen E. L.
Geophysical research letters,
28 September 2015, Letnik:
42, Številka:
18
Journal Article
Recenzirano
Odprti dostop
Recently, the feasibility of commercial shipping in the ice‐prone Northwest Passage (NWP) has attracted a lot of attention. However, very little ice thickness information actually exists. We present ...results of the first ever airborne electromagnetic ice thickness surveys over the NWP carried out in April and May 2011 and 2015 over first‐year and multiyear ice. These show modal thicknesses between 1.8 and 2.0 m in all regions. Mean thicknesses over 3 m and thick, deformed ice were observed over some multiyear ice regimes shown to originate from the Arctic Ocean. Thick ice features more than 100 m wide and thicker than 4 m occurred frequently. Results indicate that even in today's climate, ice conditions must still be considered severe. These results have important implications for the prediction of ice breakup and summer ice conditions, and the assessment of sea ice hazards during the summer shipping season.
Key Points
Ice is still quite thick in Northwest Passage and potentially hazardous for shipping
Mean ice thickness depends on age and specific source region of sea ice in previous summers
Mean ice thickness and deformation decrease with decreasing northern latitude
Kinematic alignment performed with caliper measurements and verification checks accurately co-align the femoral and tibial components with the 3 axes and joint lines of the native knee without ...ligament release and without restrictions on the degree of preoperative varus, valgus, flexion, and extension deformities and the degree of postoperative correction. Orthopedics. 2019; 42(3):126-135..
The mechanisms that control intracellular adhesion are central to the process of invasion and metastasis. Claudin-3 (CLDN3) and claudin-4 (CLDN4) are major structural molecules of the tight junctions ...that link epithelial cells. Our prior work has demonstrated that knockdown of the expression of either CLDN3 or CLDN4 produces marked changes in the phenotype of ovarian carcinoma cells including increases in growth rate in vivo, migration, invasion, metastasis, and drug resistance, similar to those produced by the epithelial-to-mesenchymal transition (EMT). We postulated that these changes may result from the ability of CLDN3 or CLDN4 to suppress EMT. In this study we found that knockdown of either CLDN3 or CLDN4 increased cell size and resulted in flattened morphology. While knockdown of CLDN3 or CLDN4 did not alter the expression of vimentin, it significantly down-regulated the level of E-cadherin and up-regulated N-cadherin expression. Conversely, over-expression of CLDN3 or CLDN4 in a cell line that does not express endogenous CLDN3 or CLDN4 decreased N-cadherin expression. Re-expression of E-cadherin in the CLDN3 or CLDN4 knockdown cells reduced migration, invasion and tumor growth in vivo. Loss of either CLDN3 or CLDN4 resulted in activation of the PI3K pathway as evidenced by increased Akt phosphorylation, elevated cellular PIP3 content and PI3K activity as well as up-regulation of the mRNA and protein levels of the transcription factor Twist. Taken together, these findings suggest that CLDN3 and CLDN4 function to sustain an epithelial phenotype and that their loss promotes EMT.
Alignment in the varus or valgus outlier range of the tibial component, knee, and limb might adversely affect the long-term results of kinematically aligned total knee arthroplasty (TKA) particularly ...when patients are selected without restricting the degree of preoperative varus-valgus and flexion deformity.
A retrospective review of all patients treated in 2007 with a primary TKA determined the 10-year implant survivorship, yearly revision rate, Oxford Knee Score, and WOMAC. All 222 knees (217 patients) were aligned kinematically using patient-specific instrumentation without restricting the degree of preoperative deformity and with the restoration of the native joint lines and limb alignment. Mechanical alignment criteria categorized the alignments of the tibial component, knee, and limb as in-range or in a varus or valgus outlier range.
The implant survivorship (yearly revision rate) was 97.5% (0.3%) for revision for any reason and 98.4% (0.2%) for aseptic failure. The percentage postoperatively aligned in the varus outlier (valgus outlier) range was 78% (0%) for the angle between the tibial component and mechanical axis of the tibia, 31% (5%) for the tibiofemoral angle of the knee according to the criteria by Ritter et al, and 7% (21%) for the hip-knee-ankle angle of the limb according to the criteria by Parratte et al. Patients grouped in the varus outlier range, valgus outlier range, and in-range had similar implant survival and function scores. The 10-year Oxford Knee Score (48 best) and WOMAC (0 best) averaged 43 and 7 points, respectively.
With the limitation that a large case series unlikely represents the full range of preoperative deformities and native alignments, treatment of patients with kinematically aligned TKA with patient-specific instrumentation without restricting the preoperative deformity did not adversely affect the 10-year implant survival, yearly revision rate, and level of function.
Level III, therapeutic study.
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