Concentration of persistant organic pollutants and mercury in seabird eggs collected in Norway

The main objective of this study was to investigate possible temporal trends of persistent organic pollutants (POPs) and mercury in eggs of herring gulls (Larus argentatus), black-legged kittiwakes (Rissa tridactyla), common guillemots (Uria aalge) and Atlantic puffins (Fratercula arctica) in Northern Norway. Eggs were collected in 1983, 1993 and 2003. Egg concentrations of POPs (PCB congeners IUPAC numbers: CB-28, 74, 66, 101, 99, 110, 149, 118, 153, 105, 141, 138, 187, 128, 156, 157, 180, 170, 194, 206, HCB, alph-HCH, beta-HCH, gamma-HCH, oxychlordane, trans-chlordane, cis-chlordane, trans-nonachlor, cis-nonachlor, p,p'-DDE, o,p'-DDD, p,p'-DDD, o,p'-DDT and p,p'-DDT) and mercury were quantified. Generally, POP levels decreased between 1983 and 2003 in all species. No significant temporal trend in mercury levels was found between 1983 and 2003.

(Supplementary Table 1) Mercury isotope values for common and thick-billed murre (Uria aalge, Uria lomvia) eggs from Alaska

Atmospheric deposition of mercury to remote areas has increased threefold since pre-industrial times. Mercury deposition is particularly pronounced in the Arctic. Following deposition to surface oceans and sea ice, mercury can be converted into methylmercury, a biologically accessible form of the toxin, which biomagnifies along the marine food chain. Mass-independent fractionation of mercury isotopes accompanies the photochemical breakdown of methylmercury to less bioavailable forms in surface waters. Here we examine the isotopic composition of mercury in seabird eggs collected from colonies in the North Pacific Ocean, the Bering Sea and the western Arctic Ocean, to determine geographical variations in methylmercury breakdown at northern latitudes. We find evidence for mass-independent fractionation of mercury isotopes. The degree of mass-independent fractionation declines with latitude. Foraging behaviour and geographic variations in mercury sources and solar radiation fluxes were unable to explain the latitudinal gradient. However, mass-independent fractionation was negatively correlated with sea-ice cover. We conclude that sea-ice cover impedes the photochemical breakdown of methylmercury in surface waters, and suggest that further loss of Arctic sea ice this century will accelerate sunlight-induced breakdown of methylmercury in northern surface waters.

Nest choice in laying hens: Effects of nest partitions and social status.

Nest choice in loose-housed laying hens is influenced by nest characteristics, position and social factors. We examined the relative preference of laying hens for two group-nests differing in the presence or absence of a partition in the middle of the nest and whether this was influenced by social status. We hypothesized that hens would prefer the partitioned nest as it provides more enclosure, and that social status would affect nest choice. Relative preference for the nests was assessed in a free choice preference test conducted in two consecutive trials each with eight groups of 20 hens from 18 to 31 weeks of age. The hens were individually marked and had access to two commercial group-nests (49 × 114 cm), one of which contained an internal wooden partition (30 × 10 cm) which divided the nest in two halves. At 28 weeks of age, the position of the nests was switched. The number of eggs laid was recorded daily. On one day each at 24 and 28 weeks of age (after the nest switch) video recordings were made of the first 5 h of daylight. From these videos we recorded the number of nest visits per egg per nest and the number of nest visits for individual hens. On one day each at 24 and 27 weeks of age we also recorded videos from within the nests to assess individual nest choice for egg-laying. In addition, we recorded aggressive interactions between individual hens during the first hour of light on one day each at 18, 24 and 27 weeks of age to establish social status. We found a relative preference for the partition nest with a greater proportion of eggs laid in these nests as well as fewer nest visits per egg. The hens were also consistent in their egg-laying location over the two days of observation. After the nest switch, however, the hens did not switch egg laying location and the number of visits per egg no longer differed between nests suggesting that the preference for the partitioned nest was only important at the beginning of lay. In addition, although social rank had no impact on preference of nest type, lower ranking hens performed more nest visits and laid their eggs slightly later on the second observation day (week 27 of age) compared with higher ranking hens. Therefore, the use of partitions could improve the attractiveness of group-nests.

Effect of bird age and storage system on physical properties of eggs from brown laying hens

A total of 108 eggs from a group of 100 brown laying hens housed in standard cages were analyzed. Thirty-six eggs were retired when the hens had 30 week of age, other 36 eggs were retired when the hens had 35 week of age and the remaining 36 eggs were retired five weeks afterwards. Each group of 36 eggs was radomly divided in three groups of 12 eggs. First group was analyzed at once, second group one was kept during one week in the refrigerator (5°C) and third group was kept also one week but on ambient temperature (25°C). Shell color, shell thickness, specific gravity, albumen height and Haugh units wre obtained. The bird age had significant effect on shell color and shell thickness, but the storage system had not influence on such variables. The hen age had not effect on specific gravity, but the storage system affected to this variable. Hen age and storage system had significant influence (P<0.05) on albumen height and Haugh units, and the interaction age × storage system was significant for these variables. The specific gravity had positive relations with shell thickness, yolk color, albumen height and Haugh units. It is concluded that bird age and storage system under high temperatures reduced the egg quality.

Sequence-Specific Interaction between the Disintegrin Domain of Mouse ADAM 3 and Murine Eggs: Role of β1 Integrin-associated Proteins CD9, CD81, and CD98

ADAM 3 is a sperm surface glycoprotein that has been implicated in sperm-egg adhesion. Because little is known about the adhesive activity of ADAMs, we investigated the interaction of ADAM 3 disintegrin domains, made in bacteria and in insect cells, with murine eggs. Both recombinant proteins inhibited sperm-egg binding and fusion with potencies similar to that which we recently reported for the ADAM 2 disintegrin domain. Alanine scanning mutagenesis revealed a critical importance for the glutamine at position 7 of the disintegrin loop. Fluorescent beads coated with the ADAM 3 disintegrin domain bound to the egg surface. Bead binding was inhibited by an authentic, but not by a scrambled, peptide analog of the disintegrin loop. Bead binding was also inhibited by the function-blocking anti-α6 monoclonal antibody (mAb) GoH3, but not by a nonfunction blocking anti-α6 mAb, or by mAbs against either the αv or β3 integrin subunits. We also present evidence that in addition to the tetraspanin CD9, two other β1-integrin-associated proteins, the tetraspanin CD81 as well as the single pass transmembrane protein CD98 are expressed on murine eggs. Antibodies to CD9 and CD98 inhibited in vitro fertilization and binding of the ADAM 3 disintegrin domain. Our findings are discussed in terms of the involvement of multiple sperm ADAMs and multiple egg β1 integrin-associated proteins in sperm-egg binding and fusion. We propose that an egg surface “tetraspan web” facilitates fertilization and that it may do so by fostering ADAM–integrin interactions.