Measurements, Chick Meals and Breeding Distribution of Dovekies (Alle alle) in Northwest Greenland

This paper reports the results of an investigation of Dovekies (Alle alle L.) breeding near Cape Atholl and Siorapaluk in the Thule District, Northwest Greenland during July and August 1978. Mean values for body measurements of breeding birds were: total length = 218.2 mm (n = 265), wing length = 122.9 mm (n - 266), tail length - 40.8 mm (n = 266) and body weight = 150.5 g (n = 209). Most measurements between the sexes were not significantly different, but mean body weight of males (153.8 g) was significantly greater than that of females (147.2 g). Body weight was highly correlated with wing length and total length in males, but not in females. Food delivered to nestlings consisted primarily of copepods (Calanus hyperboreas and C. glacialis) and amphipods (Parathemisto libellula and Apherusa glacialis). Size of chick meals delivered by male and female parents did not differ significantly and average meal weight was 3.48 g (sd = 1.24, n = 204) with mean weight of meals increasing through the chick-rearing period. General information is presented on measurements of subadults, timing of breeding, feeding areas, population size and colony attendance, and predation and disturbance. The distribution of Dovekie colonies in the Thule District is reviewed and compared with earlier information.Key words: Dovekie, morphometrics, chick diet, seabirds, NW GreenlandMots clés: Dovekie, morphométrie, régime des oisillons, oiseaux marins, nord-ouest du Groenlan

Clinical disorders affecting mesopic vision

Vision in the mesopic range is affected by a number of inherited and acquired clinical disorders. We review these conditions and summarize the historical background, describing the clinical characteristics alongside the genetic basis and molecular biological mechanisms giving rise to rod and cone dysfunction relevant to twilight vision. The current diagnostic gold standards for each disease are discussed and curative and symptomatic treatment strategies are summarized

A red knot as a black swan:How a single bird shows navigational abilities during repeat crossings of the Greenland Icecap

Despite the wealth of studies on seasonal movements of birds between southern nonbreeding locations and High Arctic breeding locations, the key mechanisms of navigation during these migrations remain elusive. A flight along the shortest possible route between pairs of points on a sphere ('orthodrome') requires a bird to be able to assess its current location in relation to its migration goal and to make continuous adjustment of heading to reach that goal. Alternatively, birds may navigate along a vector with a fixed orientation ('loxodrome') based on magnetic and/or celestial compass mechanisms. Compass navigation is considered especially challenging for summer migrations in Polar regions, as continuous daylight and complexity in the geomagnetic field may complicate the use of both celestial and magnetic compasses here. We examine the possible use of orientation mechanisms during migratory flights across the Greenland Icecap. Using a novel 2 g solar-powered satellite transmitter, we documented the flight paths travelled by a female red knotCalidris canutus islandicaduring two northward and two southward migrations. The geometry of the paths suggests that red knots can migrate across the Greenland Icecap along the shortest-, orthodrome-like, path instead of the previously suggested loxodrome path. This particular bird's ability to return to locations visited in a previous year, together with its sudden course changes (which would be appropriate responses to ambient wind fields), suggest a map sense that enables red knots to determine location, so that they can tailor their route depending on local conditions

The Vitamin B1 Metabolism of Staphylococcus aureus Is Controlled at Enzymatic and Transcriptional Levels

Vitamin B1 is in its active form thiamine pyrophosphate (TPP), an essential cofactor for several key enzymes in the carbohydrate metabolism. Mammals must salvage this crucial nutrient from their diet in order to complement the deficiency of de novo synthesis. In the human pathogenic bacterium Staphylococcus aureus, two operons were identified which are involved in vitamin B1 metabolism. The first operon encodes for the thiaminase type II (TenA), 4-amino-5-hydroxymethyl-2-methylpyrimidine kinase (ThiD), 5-(2-hydroxyethyl)-4-methylthiazole kinase (ThiM) and thiamine phosphate synthase (ThiE). The second operon encodes a phosphatase, an epimerase and the thiamine pyrophosphokinase (TPK). The open reading frames of the individual operons were cloned, their corresponding proteins were recombinantly expressed and biochemically analysed. The kinetic properties of the enzymes as well as the binding of TPP to the in vitro transcribed RNA of the proposed operons suggest that the vitamin B1 homeostasis in S. aureus is strongly regulated at transcriptional as well as enzymatic levels

A pipeline for the production of antibody fragments for structural studies using transient expression in HEK 293T cells.

We describe a pipeline for the rapid production of recombinant Fabs derived from mouse monoclonal antibodies suitable for use in structural studies. The pipeline is exemplified by the production of three Fabs derived from the monoclonal antibodies OX108 (anti-CD200 receptor), OX117 and OX119 (anti-SIRPgamma). Heavy and light chain variable domains were inserted into separate expression vectors containing resident constant regions using In-Fusion PCR cloning. Following transient co-expression in HEK 293T cells, secreted Fab fragments were purified by metal chelate chromatography and gel filtration using an automated procedure with yields of up to 4mg/L of cell culture. Following crystallization trials, diffracting crystals were obtained for the recombinant Fabs of OX108 and OX117, and their structures solved to 2.3A and 2.4A, respectively