Search results for " migration."

Cross-icecap spring migration confirmed in a high-Arctic seabird, the Ivory Gull Pagophila eburnea

2021

Seabirds rarely cross major terrestrial barriers during seasonal migration, possibly because they have a limited ability to build up fat stores. For the first time, we tracked two Ivory Gulls with GPS loggers during spring migration from the wintering area in Davis Strait to the breeding colony in north-east Greenland. While one bird migrated in March around the southern tip of Greenland, the other delayed migration until May and crossed the Greenland icecap north of 70°N, covering 1345 km in 29 h. Several aspects of the crossing were noteworthy: the track was remarkably direct, the bird made several stops (totalling 6 h) on the icecap, and the bird increased its flying altitude to nearly 3…

Domain boundary migration at multiple scales in experiment and nature

2000

Fluid Migration above a Subducted Slab-Constraints on Amount, Pathways and Major Element Mobility from Partially Overprinted Eclogite-facies Rocks (S…

2011

The Western Alpine Sesia-Lanzo Zone (SLZ) is a sliver of eclogite-facies continental crust exhumed from mantle depths in the hanging wall of a subducted oceanic slab. Eclogite-facies felsic and basic rocks sampled across the internal SLZ show different degrees of retrograde metamorphic overprint associated with fluid influx. The weakly deformed samples preserve relict eclogite-facies mineral assemblages that show partial fluid-induced compositional re-equilibration along grain boundaries, brittle fractures and other fluid pathways. Multiple fluid influx stages are indicated by replacement of primary omphacite by phengite, albitic plagioclase and epidote as well as partial re-equilibration a…

Effects of repeated short episodes of environmental acidification on Atlantic salmon (Salmo salar) from a landlocked population

2020

Abstract Chronic or repeated exposure to environmental contaminants may result in allostatic overload, a physiological situation in which the costs of coping affect long-term survival and reproductive output. Continuous measurements in Otra, the largest river in southern Norway, show the occurrence of repeated 24–48 h episodes of acidification. This work investigates the impact of repeated short acidification episodes on a unique land-locked population of normally anadromous Atlantic salmon (“Bleke”). This was done by recording physiological measures of stress and allostatic load in fish exposed for 7 days to continuous or repeated episodes of simulated environmental acidification or untrea…

Migrating neuroblasts of the rostral migratory stream are putative targets for the action of nitric oxide

2007

It has been demonstrated that the gaseous messenger nitric oxide influences cell proliferation and cell migration, and therefore affects adult neurogenesis in mammals. Here, we investigated the putative targets for this action in the rostral migratory stream of the rat. We used immunocytochemical detection of the beta1 subunit of the enzyme soluble guanylyl cyclase, which can be activated by nitric oxide. Our results under light and electron microscopy demonstrated that the migrating neuroblasts (type A cells) were beta1-immunopositive. The astrocytes (type B cells), immature precursors (type C cells) and ependymal cells (type E cells) were beta1-immunonegative. The neurochemical characteri…

Impact of climate change on migratory birds: community reassembly versus adaptation

2007

Aim Species can respond to global climate change by range shifts or by phenotypic adaptation. At the community level, range shifts lead to a turnover of species, i.e. community reassembly. In contrast, phenotypic adaptation allows species to persist in situ , conserving community composition. So far, community reassembly and adaptation have mostly been studied separately. In nature, however, both processes take place simultaneously. In migratory birds, climate change has been shown to result in both exchange of species and adaptation of migratory behaviour. The aim of our study is to predict the impact of global climate change on migratory bird communities and to assess the extent to which …

Spatial genetic structure reveals migration directionality in Mediterranean Ruppia spiralis (Western Sicily)

2022

Mediterranean salinas, originally built for salt production, function as alternative wetlands. A variety of accompanying lagoon, ditch, and marsh systems are suitable habitats for salt-tolerant submerged macrophytes and often characterized by monospecific beds of Ruppia. Traditionally, birds are considered the main dispersal vector of submerged macrophytes. However, Ruppia spiralis habitats are under marine influence and therefore interference of coastal currents in their connectivity might be expected. In this study, we aim to infer connectivity and spatial patterns from population genetic structures. Using nuclear microsatellite loci, the nuclear ribosomal cistron and chloroplast sequence…

Capacity of Gentamicin-Treated Pseudomonas aeruginosa to Induce Granulocyte Locomotion

1982

In protection against an invading parasite the host’s granulocytes play an essential role. To exert their defense the phagocytes have to be attracted to the site of parasite invasion. We have shown that Pseudomonas aeruginosa ATCC 27853 and other clinical isolates of this species can induce granulocyte migration, either directly or via generation of chemotactic activity in serum [1].

Social factors as the catalyst of emigration

2022

The objective of the study is to address the factors contributing to emigration from Latvia, in particular by highlighting the importance of social factors in the emigration decision, using the theory of push and pull factors of migration as a theoretical basis. The role of the family and the desire to improve not only the economical, but also the social and psychological conditions of families are important factors in the decision-making process, while maintaining links with Latvia. The authors argue that social factors are essential to the migration decision alongside economic factors, and in particular the family situation. The family is a resource that helps to settle in the new country…

Organ-specificity and diagnostic value of cell-mediated immunity against a liver-specific membrane protein: Studies in hepatic and non-hepatic diseas…

1975

In chronic active hepatitis (CAH, n=58) 70% of the HBsAg negative and 48% of the HBsAg positive cases showed a CMI against human liver specific proteins (HLPI). Using HBsAg as antigen only 12% of the HBsAg negative and 24% of the HBsAg positive cases gave a CMI response. On the basis of HBsAg and autoantibodies in the serum CAH patients could be divided into 4 subgroups. A close correlation between CMI against HLPI, sex, ANA and HL-A-8 could be detected. In a follow-up study of patients with acute virus B hepatitis (n=62) CMI against HBsAg was detected in 60% of the cases in the acute phase of the disease but in 15% only 3-6 months after the onset of the illness (n=40). In patients who deve…