Historical Ecology on Sandoy, Faroe Islands: Palaeoenvironmental and Archaeological Perspectives

We present palaeoenvironmental, geomorphological, archaeological, and place-name data which allow a holistic assessment of the history of landscape change on Sandoy, Faroe Islands, especially in terms of the changes that occurred in response to the colonization of the island by humans. In contrast to other situations in the North Atlantic region, there is considerable continuity in the patterns and processes of landscape evolution across the initial settlement horizon. Many of the characteristic features of post-settlement North Atlantic landscapes—absence of trees, widespread blanket mires, high rates of soil erosion—were already in place when the first people arrived. Although human impact on Sandoy appears to have been light, conversely, the unusual environment forced major alterations of the subsistence economy imported by the colonists. Settlement-era archaeological records suggest that, from the start, patterns of resource use differed substantially from the regional norm, and these differences became amplified over time as the Faroese economy created a locally sustainable cultural landscape.     

The anatomical basis of sexual dichromatism in non-iridescent ultraviolet-blue structural coloration of feathers

Despite extensive research on the evolution of avian dichromatism, the anatomical bases for differences between the sexes in species with structurally coloured plumage remain largely unknown. Using full‐spectrum spectrometry and transmission electron microscopy, we compared the colour and morphology of rump feathers of male and female eastern bluebirds (Sialia sialis). The ultraviolet (UV)‐blue feather colour in this species is caused by coherent scattering of light within the medullary ‘spongy layer’ of feather barbs. This spongy layer lies beneath a keratin cortex and on top of a layer of melanin granules that surround a hollow central vacuole. Irregularly shaped electron‐dense regions are present within the cortex. Male and female S. sialis differed substantially in their plumage colour and feather structure. A backwards logistic regression predicted sex with 100% accuracy using the colour variables brightness, UV‐violet (UV‐V) chroma and spectral saturation. A second backwards logistical regression predicted sex with 100% accuracy using relative cortex area and size of air spaces. Thus, S. sialis are dimorphic both in colour and in the structures causing this colour. Multiple regression analyses using data pooled from both sexes indicated that multiple features of feather barb structure contributed to colour variation in complex ways. Brightness was negatively related to the relative surface area of cortex in barb cross‐sections. Hue was positively related and UV‐V chroma was negatively related to the distance between scattering elements (i.e. keratin rods and air spaces) in the spongy layer. In contrast, hue was negatively related and UV‐V chroma was positively related to the thickness of the spongy layer. UV‐V chroma was also negatively related to the relative area of electron‐dense regions in the cortex. Spectral saturation was negatively related to the distance between scatterers and the standard error of the size of air spaces. These results suggest that the dimensions of spongy‐layer elements are critical to colour production, but that UV‐blue coloration can also be modified by the cortex and the thickness of the spongy layer. © 2005 The Linnean Society of London, Biological Journal of the Linnean Society, 2005, 84 , 259–271.     

Swim or hide: predator cues cause species specific reactions in young fish larvae

The anti‐predator behaviour of first‐feeding (9 mm total length) hatchery‐reared pike Esox lucius larvae and wild‐caught three‐spined stickleback Gasterosteus aculeatus larvae was studied in the presence of chemical and visual signals from a fish predator. The results clearly showed that both fish species detected the predator by chemical signals alone but the combined chemical and visual signals caused stronger and more diverse reactions. Subsequent to predator detection, their swimming activity decreased, they attacked zooplankton less frequently and spent more time in the vegetation. Fishes differed in their anti‐predator responses. Pike reacted more clearly to chemical signals alone while three‐spined stickleback needed both chemical and visual cues to assess the predation risk. The strongest reaction was the reduction in swimming activity in the three‐spined stickleback (38% decrease) and a decrease in attack rate of the pike (39% decrease), but only when a refuge was available. Pike were more dependent on the vegetation cover showing almost no anti‐predator responses in the absence of a refuge. In addition, there was a difference in the refuge use of three‐spined stickleback between different macrophytes, indicating a complex or dense structure, which was difficult to penetrate or chemical excretion in one of them.     

Inactivation and sensitization of tumor cells after transfection with gene Bax

Experiments on the transfection of cultured SKOV3 tumor cells of human ovarian adenocarcinoma and HeLa cells of human cervical carcinoma with gene Bax have demonstrated that SKOV3 cells are highly sensitive to the protein product of this gene, whereas the sensitivity of HeLa cells is substantially lower. HeLa cells obtained as a result of Bax transfection and subsequent selection are characterized by an extremely high Bax protein content and a hypersensitivity to doxorubicin. All Bax-transfected SKOV3 cells with an increased Bax content have died. In the SKOV3 cell line, a Bax exon 3 mutation has been found that corresponds to genotype G7/G9, whereas the native type of the Bax gene corresponds to genotype G8/G8. The results suggest that the G7/G9 mutation in Bax exon 3 deprives the Bax protein of proapoptotic activity.Translated from Molekulyarnaya Biologiya, Vol. 39, No. 1, 2005, pp. 40–47.Original Russian Text Copyright © 2005 by Rodina, Sladkova, Obuchova, Vezirkhanova, Moskaleva, Prusakova, Beletskii, Belushkina, Strelnikov, Ivanov, S. Severin, E. Severin.     

Thermoplastic starch modification during melt processing: Hydrolysis catalyzed by carboxylic acids

The melt processing of glycerol-plasticized starch in the presence of non-volatile carboxylic acids resulted in a progressive loss of its molar mass, because the residual moisture in the mixture induced an acid-catalyzed hydrolysis of the ether linkages in its polysaccharide chains. The study of this reaction provided a useful means of adjusting its course and thus of preparing starch materials with controlled properties.     

Effect of food composition on egg production and hatching success rate of two copepod species (Calanoides carinatus and Rhincalanus nasutus) in the Benguela upwelling system

We have analysed the daily egg production (EPR) and hatchingsuccess rates of the calanoid copepods Calanoides carinatusand Rhincalanus nasutus as a function of nano- and microplanktonconcentration and composition in the northern Benguela upwellingsystem off Namibia. Food concentration explained 55% (R. nasutus)to 62% (C. carinatus) of the EPR variability. We found no relationbetween the residuals of the food concentration–EPR regressionand the percentage of the different taxonomic components ofthe nano- and microplankton. Nor was there a relation with theproportion of the diatom Skeletonema costatum that dominatedthe major blooms or with the number of nano- and microplanktonspecies. We conclude that food quality differences could notbe attributed to the relative composition of microplanktonicparticles of the different groups (i.e. taxonomic composition).