Winter climate affects subsequent breeding success of common eiders

The phenology of spring migration depends on the severity of the preceding winter and approaching spring. This severity can be quantified using the North Atlantic Oscillation (NAO) index; positive values indicate mild winters. Although milder winters are correlated with earlier migration in many birds in temperate regions, few studies have addressed how climate‐induced variation in spring arrival relates to breeding success. In northern Europe, the NAO‐index correlates with ice cover and timing of ice break‐up of the Baltic Sea. Ice cover plays an important role for breeding waterfowl, since the timing of ice break‐up constrains both spring arrival and onset of breeding. We studied the effects of the winter‐NAO‐index and timing of ice break‐up on spring migration, laying date, clutch size, female body condition at hatching and fledging success of a short‐distance migrant common eider (Somateria mollissima) population from SW Finland, the Baltic Sea, 1991–2004 (migration data 1979–2004). We also examined the correlation between the NAO‐index and the proportion of juvenile eiders in the Danish hunting bag, which reflects the breeding success on a larger spatial scale. The body condition of breeding females and proportion of juveniles in the hunting bag showed significant positive correlations with the NAO, whereas arrival dates showed positive correlations and clutch size and fledging success showed negative correlations with the timing of ice break‐up. The results suggest that climate, which also affects ice conditions, has an important effect on the fledging success of eiders. Outbreaks of duckling disease epidemics may be the primary mechanism underlying this effect. Eider females are in poorer condition after severe winters and cannot allocate as much resources to breeding, which may impair the immune defense of ducklings. Global climate warming is expected to increase the future breeding success of eiders in our study population.     

Genetic maladaptation of coastal Douglas-fir seedlings to future climates

Climates are expected to warm considerably over the next century, resulting in expectations that plant populations will not be adapted to future climates. We estimated the risk of maladaptation of current populations of coastal Douglas-fir (Pseudotsuga menziesii var. menziesii) to future climates as the proportion of nonoverlap between two normal distributions where the means and genetic variances of current and future populations are determined from genecological models derived from seedling common garden studies. The risk of maladaptation was large for most traits when compared with the risk associated with current transfers within seed zones, particularly for the more drastic climate change scenario. For example, the proportion of nonoverlap for a composite trait representing bud set, emergence, growth, and root : shoot ratio was as high as 0.90. We recommend augmenting within-population variation by mixing local populations with some proportion of populations from lower elevations and further south. Populations expected to be adapted to climates a century from now come from locations as far down in elevation as 450–1130 m and as far south in latitude as 1.8–4.9°.     

Seedling Nitrate Reductase Activity and Nitrate Partitioning in Maize (Zea mays L.) Strains Divergently Selected For Post-anthesis Leaf-Lamina Nitrate Reductase Activity

Two experiments were conducted to evaluate the effects of phenotypicrecurrent selection for high and low post-anthesis leaf-laminain vivo NRA on nitrate uptake, nitrate partitioning and in vitroNRA of seedling roots and leaves. In Experiment 1, intact plantsof cycle 0, 4, and 6 of the high and low NRA strains were grownon NH₄-N for 11 d, then exposed to 1.0 mol m^–3 KNO₃, andcultures sampled at 6 h and 28 h (induction and post-inductionperiods). Nitrate uptake, tissue nitrate concentration and invitro NRA were determined. The pattern of response to selectionin seedling leaf NRA was similar to that observed for in vivoNRA of field grown plants. Leaf NRA increased between 6 h and28 h. Root NRA was not affected by selection or sampling time.Treatments differed in total fresh weight but not in reductionor uptake of nitrate per unit weight, indicating a lack of correspondencebetween NRA and reduction and supporting the idea that concomitantreduction by NR is not obligatorily linked to nitrate influxin the intact plant. In Experiment 2, dark-grown plants of cycle 0, and 6 of thehigh and low NRA strains were cultured without N, detopped onday 6, transferred the following day to 0-75 mol m^–3 KNO₃and sampled at 6 h and 28 h. In contrast to Experiment 1, selectionpopulations differed in nitrate reduction and root NRA, whichby 28 h reached higher average levels than root NRA of intactplants. Translocation and reduction were inversely related amongstrains within each sampling time. The high level of translocationin detopped plants of the low NRA strain was difficult to reconcilewith its low leaf NRA level of Experiment 1. It is suggestedthat nitrate transport in detopped roots is altered relativeto the intact system in a way which permits greater NRA inductionand nitrate reduction. The results indicate that nitrate partitioningby detopped root systems should be interpreted with caution. Key words: Zea, nitrate reductase activity, nitrate uptake, nitrate reduction, nitrate partitioning, selection     

In vivo and in vitro characterization of novel microparticulates based on hyaluronan and chitosan hydroglutamate

This study examined the application of previously characterized microparticles composed of hyaluronan (HA) and chitosan hydroglutamate (CH) as well as novel microparticles consisting of both polymers (HA/CH) to improve the nasal delivery of a model drug. The rabbit bioavailabilities of gentamicin incorporated in HA, CH, and HA/CH microparticles were increased 23-, 31-, and 42-fold, respectively, compared with the control intranasal solution of gentamicin, indicating that all test microparticles were retained for longer periods on the nasal mucosa of the rabbits as supported by previous in vitro dissolution as well as frog palate mucoadhesion studies, thereby improving drug absorption. The higher bioavailabilities of CH-based formulations (CH and HA/CH) suggest the penetration-enhancing effects of CH may also be partially responsible for the improvement. A model was developed, based on a glass impinger device, to deliver dry powder formulations reproducibly onto the surface of cultured cell monolayers. In vitro permeability and fluorescence microscopy studies on the tight junctions of the 16HBE14o- cell lines further confirmed the ability of CH-based formulations to enhance penetration. Furthermore, the in vitro absorption profile from cell culture studies was consistent with those determined from in vivo studies. The complementary effect from the mucoadhesive nature of HA coupled with the penetration-enhancing effects of CH makes the novel HA/CH formulation a promising nasal delivery system.     

Biosynthesis of Choline and Ethanolamine Phospholipids in Crithidia fasciculata*

The incorporation of radioactivity from [1,2-³⁴C]choline, [1,2-³⁴C]ethanolamine, [3-¹⁴C]serine and [methyl-¹⁴C]methionine into lipids was studied in growing cultures of Crithidia fasciculata. Lecithin was formed both from choline and by the methylation of phosphatidylethanolamine. Mono- and dimethylphosphatidylethanolamines were present in no more than trace amounts. Growth of the protozoa in media containing choline (1 mM) did not decrease synthesis by the methylation pathway. Phosphatidylethanolamine was formed from ethanolamine. Radioactivity from serine also was present in both phosphatidylethanolamine and lecithin; however, the presumed intermediate, phosphatidylserine, could not be detected.