Small Intestine Inflammation in Roquin-Mutant and Roquin-Deficient Mice

Roquin, an E3 ubiquitin ligase that localizes to cytosolic RNA granules, is involved in regulating mRNA stability and translation. Mice that have a M199R mutation in the Roquin protein (referred to as sanroque or Roquin^san/san mice) develop autoimmune pathologies, although the extent to which these occur in the intestinal mucosa has not been determined. Here, we demonstrate that Roquin^san/san mice reproducibly develop intestinal inflammation in the small intestine but not the colon. Similarly, mice generated in our laboratory in which the Roquin gene was disrupted by insertion of a gene trap cassette (Roquin^gt/gt mice) had small intestinal inflammation that mimicked that of Roquin^san/san mice. MLN cells in Roquin^san/san mice consisted of activated proliferating T cells, and had increased numbers of CD44^hi CD62L^lo KLRG1⁺ short-lived effector cells. Proportionally more small intestinal intraepithelial lymphocytes in Roquin^san/san mice expressed the ICOS T cell activation marker. Of particular interest, small intestinal lamina propria lymphocytes in Roquin^san/san mice consisted of a high proportion of Gr-1⁺ T cells that included IL-17A⁺ cells and CD8⁺ IFN-γ⁺ cells. Extensive cytokine dysregulation resulting in both over-expression and under-expression of chemotactic cytokines occurred in the ileum of Roquin^san/san mice, the region most prone to the development of inflammation. These findings demonstrate that chronic inflammation ensues in the intestine following Roquin alteration either as a consequence of protein mutation or gene disruption, and they have implications for understanding how small intestinal inflammation is perpetuated in Crohn''s disease (CD). Due to the paucity of animal models of CD-like pathophysiology in the small intestine, and because the primary gene/protein defects of the Roquin animal systems used here are well-defined, it will be possible to further elucidate the underlying genetic and molecular mechanisms that drive the disease process.     

Contrasting sensitivity of nestling and fledgling Barn Swallow Hirundo rustica body mass to local weather conditions

Local weather can influence the growth and development of young birds either indirectly, by modifying prey availability, or directly, by affecting energetic trade-offs. Such effects can have lasting implications for life history traits, but the nature of these effets may vary with the developmental stage of the birds, and over timescales from days to weeks. We examined the interactive effects of temperature, rainfall and wind speed on the mass of nestling and fledgling Barn Swallows Hirundo rustica both on the day of capture and averaging weather across the time since hatching. At the daily timescale, nestling mass was negatively correlated with temperature, but the strength of this association depended on the level of rainfall and wind speed; nestlings were typically heavier on dry or windy days, and the negative effect of temperature was strongest under calm or wet conditions. At the early lifetime timescale (i.e. from hatching to pre-fledging), nestling mass was negatively correlated with temperature at low wind speed. Fledgling body mass was less sensitive to weather; the only weather effect evident was a negative correlation with temperature at the daily scale under high rainfall that became slightly positive under low rainfall. These changes are consistent with weather effects on the availability and distribution of insects within the landscape (e.g. causing high concentrations of flying insects) and with the effects of weather variation on nest microclimate. These results together demonstrate the impacts of weather on chick growth, over immediate (daily) and longer term (nestling/fledgling lifetime) timescales. This shows that sensitivity to local weather conditions varies across the early lifetime of young birds (nestling–fledgling stages) and illustrates the mechanisms by which larger scale (climate) variations influence the body condition of individuals.     

Ecomorphology of eye shape and retinal topography in waterfowl (Aves: Anseriformes: Anatidae) with different foraging modes

Despite the large body of literature on ecomorphological adaptations to foraging in waterfowl, little attention has been paid to their sensory systems, especially vision. Here, we compare eye shape and retinal topography across 12 species representing 4 different foraging modes. Eye shape was significantly different among foraging modes, with diving and pursuit-diving species having relatively smaller corneal diameters compared to non-diving species. This may be associated with differences in ambient light intensity while foraging or an ability to tightly constrict the pupil in divers in order to facilitate underwater vision. Retinal topography was similar across all species, consisting of an oblique visual streak, a central area of peak cell density, and no discernible fovea. Because the bill faces downwards when the head is held in the normal posture in waterfowl, the visual streak will be held horizontally, allowing the horizon to be sampled with higher visual acuity. Estimates of spatial resolving power were similar among species with only the Canada goose having a higher spatial resolution. Overall, we found no evidence of ecomorphological adaptations to different foraging modes in the retinal ganglion cell layer in waterfowl. Rather, retinal topography in these birds seems to reflect the ‘openness’ of their habitats.     

Survival and behavior of juvenile steelhead trout (Oncorhynchus mykiss) in two estuaries in Oregon, USA

Anadromous salmonids are viewed as a prized commodity and cultural symbol throughout the Pacific coast of North America. Unfortunately, several native salmonid populations are threatened or at risk of extinction. Despite this, little is known about the behavior and survival of these fish as the juveniles transition from freshwater to the ocean. Our primary objectives were to estimate survival of juvenile steelhead migrating between trapping sites and the ocean and evaluate whether survival in the estuary varies temporally (within a year) or spatially (within and between estuaries) within the same distinct population segment. We also evaluated whether flow or fork length were correlated with survival and collected information on variables that have been demonstrated to affect smolt survival in other studies to lend insight regarding differences in survival estimates between basins. We compared run timing, migration rate, survival, condition factor, age composition and time of residence in the estuary for steelhead outmigrants from each basin and measured parasite loads in outmigrating steelhead to evaluate potential differences in parasite density and parasite community between basins. In 2009, we implanted acoustic transmitters in 139 wild steelhead smolts in two small rivers on the Oregon Coast. In general, only 40–50 % of the wild steelhead smolts tagged at upstream smolt traps were detected entering the ocean. The majority of mortality occurred in the lower estuary near the ocean. Wild steelhead smolts typically spent less than 1 day in the estuary in both basins. Using similar data from previous studies in the Nehalem and Alsea basins, we showed that survival appears to be negatively correlated with flow in most releases, and in 2009 fork length was not correlated with survival. Our observations provide baseline information on factors that could influence smolt survival through the estuary as well as smolt to adult survival in these basins, and emphasize the importance of monitoring smolt survival in the estuary.     

Field-based video observations of wild barnacle cyprid behaviour in response to textural and chemical settlement cues

Many marine invertebrate larvae respond behaviourally to environmental settlement cues, yet behaviours are often only inferred from settlement patterns or are limited to laboratory studies. The behaviour of wild cypris larvae of Semibalanus balanoides L. was filmed on settlement tiles in the field. Tiles were of five different textures with a nested treatment of crude conspecific adult extract (AE). The effects of texture and AE on eleven defined behaviours were analysed. Texture affected the gross and net exploratory distances, velocity, acceleration and time spent exploring. AE attracted more cyprids during the first minute of immersion and increased the time spent on surfaces. Relatively few arrivals that either travel far and fast, or exit the surface rapidly, may indicate a lower chance of settlement. An increase in time spent on a surface may increase the probability of being in contact with the surface when the sign stimulus to settle occurs.     

Exploratory behaviour of barnacle larvae in field conditions

The aim of this work was to develop techniques for the real time filming of Semibalanus balanoides cyprid larvae in the field in order to describe the exploratory behaviour of S. balanoides cyprids under natural field conditions. The underwater camera system consisted of a high resolution, remotely controlled colour camera attached to a cradle which could be deployed from a pier. A light utilising a battery of far‐red light‐emitting diodes (λ_min = 615 nm) was used for filming at night. Transparent acrylic treated with barnacle settlement factor and smooth green polyester tiles were used as targets. From the films the tracks of the exploring cyprids were digitised from the 30 min trials. During five, 30 min trials a total of 1014 cyprids explored the surface. The numbers of cyprids exploring the surface varied from 49 to 522 cyprids per trial, and a Monte‐Carlo randomisation model showed that larval supply was random or aggregated. The mean exploration time spent on the target was 163 s with a mean distance travelled on the target of 8.5 cm. Exploratory track length was related to water current velocity by a negative curvilinear regression (R² = 0.92, F = 45.65, p < 0.05). There were significant differences in exploratory behaviour between day and night for total distance travelled (p < 0.001), straight line distance (p < 0.001) and velocity (p < 0.001) and the mean heading angle of the exploratory track (p < 0.01). The results are discussed in relation to settlement patterns and the screening of antifouling surfaces.     

Test of an antifouling treatment on tuna fish-cages in Boston Bay,Port Lincoln,South Australia

Abstract

A test of the antifouling properties of Wattyl NetClear® was conducted on fish farms containing southern bluefin tuna (Thunnus maccoyii) during a 6-month period (February-July 2002). Wattyl NetClear® is a water-based synthetic latex-based coating where the active antifouling agent is a mixture of two isothiazolinones likely to affect both biochemical conditioning and bacterial colonisation. The development of fouling was monitored using underwater stereo-photogrammetry on 3 treated and 3 untreated net cages with the main factors treatment, depth and cage nested within treatment. A significant treatment and depth effect was found but variable through time and in some instances with significant cage effects. By the end of the study, the difference in fouling load between treated and untreated nets was 14.7%. In total 72% of all free-space data points were on treated nets. The dominating fouling organisms were Enteromorpha sp. and sponges with low settlement of blue mussel and paper oysters. Passive deposition of tuna faeces contributed significantly to the cover. The largest cover of fouling was observed in April-May with a dominance of sponges in June-July. Enteromorpha sp. dominated shallow depths while sponges dominated at deeper levels. Tuna faeces were distributed independent of depth but varied with time. The results showed that fouling of fish cages consisted of both active settlement and passive deposition, the latter independent on antifouling treatment.