Seasonal variation in the lateral distribution of mayfly nymphs in a boreal river

Seasonal variations in the lateral distribution of mayfly nymphs were investigated in the North Swedish river Vindelälven; a river with large seasonal differences in water level, current velocity and ice conditions, A total of 22 mayfly species about equally divided between summer and winter species were found along a single transect. At low water level in late summer and autumn most species were distributed over the whole transect. In winter the populations occupying the littoral moved into deeper water, so avoiding the ice. Only very small mortalities were detected in the ice. Prior to the spring flood most characteristically still water species moved to the shallow uppermost littoral while lotic species and the burrowing Ephemera vulgata L. did not show the same aggregation near the shore. It is suggested that these lateral movements allow the nymphs to avoid adverse environmental conditions and to exploit food resources over the whole transect.     

Colony connectivity of Pacific Coast double-crested cormorants based on post-breeding dispersal from the region's largest colony

To reduce conflicts with fish resources, other colonial waterbirds, and damage to habitats, double-crested cormorants (Phalacrocorax auritus) are currently controlled (lethally and non-lethally) throughout much of their range. Concerns are growing over the Pacific Coast's largest double-crested cormorant colony at East Sand Island (ESI), Oregon near the mouth of the Columbia River, where cormorants forage on juvenile salmonids, many of which are listed under the United States Endangered Species Act. Management of this colony is currently under consideration and may call for a redistribution of a portion of this colony numbering more than 12,000 breeding pairs in 2009. We investigated regional and site-specific connectivity of ESI cormorants using satellite-telemetry to track post-breeding dispersal. Cormorants dispersed widely west of the Cascade-Sierra Nevada Mountains from British Columbia, Canada to northern Mexico. Tracking data demonstrated direct connectivity between the double-crested cormorant colony at ESI and nesting sites throughout the dispersal area. Results of this study indicate that some cormorants from ESI could disperse to prospect for nesting sites throughout much of the western portion of the range of the Western Population; however, regional variation in connectivity with the ESI population, distance from ESI, and site-specific nesting history will likely result in variable prospecting rates among regions and sub-regions. Management efforts aimed at redistributing ESI cormorants across western North America (e.g., social attraction or dissuasion techniques) might be best allocated to areas or sites known to be used by tagged cormorants, particularly those sites with an established nesting history. © 2012 The Wildlife Society.     

Nutritional status and endocrine response to hemorrhage

Hyperglycemia-inducing hyperosmolality has recently been proven beneficial in the maintenance of blood volume and extracellular fluid volume during early hemorrhagic hypotension. Fed animals benefitted from better plasma refill compared with starved ones when subjected to equal blood loss. Using lightly sedated fed and 24-30 h starved rats, hormones with relevance to glucose homeostasis were studied during 90 min of hemorrhagic hypotension of 70 mmHg (1 mmHg = 133.32 Pa). Marked differences in the overall hormonal developments were found between the two groups. In fed rats, insulin and glucagon responses were initially attenuated, while somatostatin increased to an early peak level at 30 min, returning to basal at 90 min. In starved rats, somatostatin increased gradually during the 90 min. Adrenaline release was massive in both groups. Corticosterone showed no increase from basal levels in the fed group during hemorrhage, while starved rats increased their basal level fourfold already at 30 min. These data are presented as evidence that changing nutritional status alters hormonal response to hypovolemic stress.     

Asymmetric competition between distant taxa: poecilid fishes and water striders

Summary Competition for water surface prey between fish (Priapichtus annectens: Poeciliidae) and water striders (Potamobates unidentatus: Gerridae) was studied in the laboratory and in pools in a small tropical stream. Laboratory experiments showed that fish depressed activity and foraging success of water striders. Large fish (4–5 cm) had a greater effect than small fish (2–3 cm). The field experiment showed that competition was highly asymmetric. Presence of fish decreased water strider foraging success while the reverse interaction was insignificant. It is suggested that the higher individual foraging success of the fish, harassment of water striders by fish and the use of an exclusive resource, benthic invertebrates, by the fish, contribute to this pattern. Habitat use differed between the two species. Fish used the deeper parts of stream pools and water striders used the shallower parts of the pools. Asymmetric interference and exploitation competition may force water striders to use shallow edge habitats.     

KDR activation is crucial for VEGF165-mediated Ca2+ mobilization in human umbilical vein endothelial cells

We have prepared apolyclonal mouse antibody directed against the first threeimmunoglobulin-like domains of the kinase insert domain-containingreceptor (KDR) tyrosine kinase. It possesses the ability to inhibitbinding of the 165-amino acid splice variant of vascular endothelialcell growth factor (VEGF₁₆₅) torecombinant KDR in vitro as well as to reduceVEGF₁₆₅ binding to human umbilical vein endothelial cells (HUVEC). These results confirm that the firstthree immunoglobulin-like domains of KDR are involved in VEGF₁₆₅ interactions. The anti-KDRantibody is able to completely blockVEGF₁₆₅-mediated intracellularCa²⁺ mobilization in HUVEC.Therefore, it appears that binding of VEGF₁₆₅ to the fms-like tyrosinekinase (Flt-1) in these cells does not translate into aCa²⁺ response. This is furtherexemplified by the lack of response to placental growth factor (PlGF),an Flt-1-specific ligand. Additionally, PlGF is unable to potentiatethe effects of submaximal concentrations ofVEGF₁₆₅. Surprisingly, theVEGF-PlGF heterodimer was also very inefficient at eliciting aCa²⁺ signaling event in HUVEC. Weconclude that KDR activation is crucial for mobilization ofintracellular Ca²⁺ in HUVEC inresponse to VEGF₁₆₅.

     

Association of C3 and C4A complement types with familial amyloidotic polyneuropathy

A mutant variant of the serum protein transthyretin (TTR-met30) appears to be a necessary but not sufficient condition for the development of familial amyloidotic polyneuropathy (FAP). We have studied a number of serum protein markers (alpha 1-antitrypsin, properdin factor B, C3, C4A, C4B, haptoglobin, transferrin and group-specific component) in FAP patients and healthy controls in an attempt to identify additional pathogenic factors which may influence the risk for developing FAP in male and female patients as well as the age of onset of the disease. Statistically significant associations were found in the complement systems C3 and C4A. The C3F variant was significantly increased in all FAP patients with a relative risk (RR) of 2.0, more pronounced in female patients (RR = 2.6) and patients with an early onset of the disease (RR = 4.5). In the FAP patients only the variants A3 and A4 were found in the C4A system. C4A3 was found in all patients, which was significantly higher than in the controls. The remaining serum protein systems showed no statistically significant associations with FAP. The results suggest that genetic variants of complement factors C3 and C4A may interact with the mutant TTR-met30 by modifying the expression and onset of FAP.