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Spiders at southern latitudes commonly produce multiple clutches, but this has not been observed at high latitudes where activity seasons are much shorter. Yet the timing of snowmelt is advancing in the Arctic, which may allow some species to produce an additional clutch. To determine if this is already happening, we used specimens of the wolf spider Pardosa glacialis caught by pitfall traps from the long-term (1996–2014) monitoring programme at Zackenberg, NE Greenland. We dissected individual egg sacs and counted the number of eggs and partially developed juveniles, and measured carapace width of the mothers. Upon the discovery of a bimodal frequency distribution of clutch sizes, as is typical for wolf spiders at lower latitudes producing a second clutch, we assigned egg sacs to being a first or second clutch depending on clutch size. We tested whether the median capture date differed among first and second clutches, whether clutch size was correlated to female size, and whether the proportion of second clutches produced within a season was related to climate. We found that assigned second clutches appeared significantly later in the season than first clutches. In years with earlier snowmelt, first clutches occurred earlier and the proportion of second clutches produced was larger. Likely, females produce their first clutch earlier in those years which allow them time to produce another clutch. Clutch size for first clutches was correlated to female size, while this was not the case for second clutches. Our results provide the first evidence for Arctic invertebrates producing additional clutches in response to warming. This could be a common but overlooked phenomenon due to the challenges associated with long-term collection of life-history data in the Arctic. Moreover, given that wolf spiders are a widely distributed, important tundra predator, we may expect to see population and food web consequences of their increased reproductive rates.

Aim Renal fibrosis is a major driver of chronic kidney disease, yet current treatment strategies are ineffective in attenuating fibrogenesis. The cyclooxygenase/prostaglandin system plays a key role in renal injury and holds great promise as a therapeutic target. Here, we used a translational approach to evaluate the role of the PGE2‐EP1 receptor in the pathogenesis of renal fibrosis in several models of kidney injury, including human (fibrotic) kidney slices. Methods The anti‐fibrotic efficacy of a selective EP1 receptor antagonist (SC‐19220) was studied in mice subjected to unilateral ureteral obstruction (UUO), healthy and fibrotic human precision‐cut kidney slices (PCKS), Madin‐Darby Canine Kidney (MDCK) cells and primary human renal fibroblasts (HRFs). Fibrosis was evaluated on gene and protein level using qPCR, western blot and immunostaining. Results EP1 receptor inhibition diminished fibrosis in UUO mice, illustrated by a decreased protein expression of fibronectin (FN) and α‐smooth muscle actin (αSMA) and a reduction in collagen deposition. Moreover, treatment of healthy human PCKS with SC‐19220 reduced TGF‐β‐induced fibrosis as shown by decreased expression of collagen 1A1, FN and αSMA as well as reduced collagen deposition. Similar observations were made using fibrotic human PCKS. In addition, SC‐19220 reduced TGF‐β‐induced FN expression in MDCK cells and HRFs. Conclusion This study highlights the EP1 receptor as a promising target for preventing both the onset and late stage of renal fibrosis. Moreover, we provide strong evidence that the effect of SC‐19220 may translate to clinical care since its effects were observed in UUO mice, cells and human kidney slices.

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This is an open access article under the terms of the Creat ive Commo ns Attri bution-NonCo mmercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.