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Journal articles on the topic 'Migratory paths'
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1
Hines, James R. "The Flight Paths of Migratory Corporations." Journal of Accounting, Auditing & Finance 6, no. 4 (1991): 447–79. http://dx.doi.org/10.1177/0148558x9100600404.
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Fossette, Sabrina, Charlotte Girard, Milagros López-Mendilaharsu, et al. "Atlantic Leatherback Migratory Paths and Temporary Residence Areas." PLoS ONE 5, no. 11 (2010): e13908. http://dx.doi.org/10.1371/journal.pone.0013908.
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Jenner, K. C. S., M.-N. M. Jenner, and K. A. McCabe. "GEOGRAPHICAL AND TEMPORAL MOVEMENTS OF HUMPBACK WHALES IN WESTERN AUSTRALIAN WATERS." APPEA Journal 41, no. 1 (2001): 749. http://dx.doi.org/10.1071/aj00044.
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Through compilation of historical whaling data, together with recent aerial and boat-based survey data, a general framework for the overall peaks of migration has been estimated for the temporal and spatial movements of Group IV humpback whales along the Western Australian coast.The migratory paths of humpback whales along the Western Australian coast lie within the continental shelf boundary or 200 m bathymetry. Major resting areas along the migratory path have been identified at Exmouth Gulf (southern migration only) and at Shark Bay. The northern endpoint of migration and resting area for reproductively active whales in the population appears to be Camden Sound in the Kimberley. A 6,750 square km2 area of the Kimberley region, inclusive of Camden Sound, has also been identified as a major calving ground. The northern and southern migratory paths have been shown to be divergent at the Perth Basin, Dampier Archipelago and Kimberley regions. In all cases the northern migratory route is further off-shore.
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STERRITT, C. "Migratory paths of ursotocin producing neurons in the deueloping avianhypothalamus." Journal of the Society for Gynecologic Investigation 2, no. 2 (1995): 352. http://dx.doi.org/10.1016/1071-5576(95)94532-y.
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Harper, Scott E., and Alan M. Martin. "Transnational Migratory Labor and Filipino Fathers." Journal of Family Issues 34, no. 2 (2012): 270–90. http://dx.doi.org/10.1177/0192513x12462364.
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Transnational migratory labor remains a primary method many Filipinos use in an effort to gain financial security for their families. Based on data collected from an urban Southern Visayan province during the summer of 2007, this study examined a sample of 116 OFW (Overseas Filipino Workers) families and a sample of 99 traditional two-parent households. Comparative analyses revealed that mothers from OFW families demonstrated lower levels of warmth when compared with mothers from two-parent homes. Children from OFW families were reported to demonstrate greater internalizing and externalizing problems when compared with children from homes in which both parents lived in the home. Subsequent regression analyses showed that fathers who worked abroad may contribute to mother behaviors and child outcomes in certain direct and indirect paths.
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Yamauchi, A., and Y. Matsumiya. "Population dynamics and fishery policy for migratory resources with two migration paths." Canadian Journal of Fisheries and Aquatic Sciences 54, no. 10 (1997): 2303–13. http://dx.doi.org/10.1139/f97-137.
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The population dynamics and fishery policy for a migratory resource with two migration paths are analyzed, based on the supposition that the resource separates into two groups, each migrating along and caught on a different path, after reproduction in a limited area. Two possible mechanisms determining individual migration paths are considered: (i) ``nongenetically controlled'' migration and (ii) ``genetically controlled'' migration. Initially, the relationships between the resource population dynamics and the fishery are analyzed for both these cases. Based on these results, the optimal fishery policy for each migration path is analyzed. Two criteria to be maximized were considered: (i) the ``game situation,'' which aims to maximize catches on each fishery path, and (ii) the ``cooperative situation,'' which aims to maximize the total, overall catch on both paths. In the case of genetically controlled migration, a fishery based on one path negatively affects recruitment on that path but positively affects recruitment on the alternative path. In both the nongenetically controlled and genetically controlled migration cases, the cooperative policy resulted in higher overall maximum catch, especially in the latter case. In the genetically controlled migration case, convergence to equilibrium is often slow, the rate being affected by density dependence of mortalities.
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Lei, Jialin, Yifei Jia, Aojie Zuo, et al. "Bird Satellite Tracking Revealed Critical Protection Gaps in East Asian–Australasian Flyway." International Journal of Environmental Research and Public Health 16, no. 7 (2019): 1147. http://dx.doi.org/10.3390/ijerph16071147.
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Most migratory birds depend on stopover sites, which are essential for refueling during migration and affect their population dynamics. In the East Asian–Australasian Flyway (EAAF), however, the stopover ecology of migratory waterfowl is severely under-studied. The knowledge gaps regarding the timing, intensity and duration of stopover site usages prevent the development of effective and full annual cycle conservation strategies for migratory waterfowl in EAAF. In this study, we obtained a total of 33,493 relocations and visualized 33 completed spring migratory paths of five geese species using satellite tracking devices. We delineated 2,192,823 ha as the key stopover sites along the migration routes and found that croplands were the largest land use type within the stopover sites, followed by wetlands and natural grasslands (62.94%, 17.86% and 15.48% respectively). We further identified the conservation gaps by overlapping the stopover sites with the World Database on Protected Areas (PA). The results showed that only 15.63% (or 342,757 ha) of the stopover sites are covered by the current PA network. Our findings fulfil some key knowledge gaps for the conservation of the migratory waterbirds along the EAAF, thus enabling an integrative conservation strategy for migratory water birds in the flyway.
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Negura, Lilian, Corinna Buhay, and Annamaria Silvana de Rosa. "Mirrored Social Representations of Canadian Caseworkers with Migratory Paths Intervening with Refugees in the Host Country." International Journal of Environmental Research and Public Health 18, no. 16 (2021): 8648. http://dx.doi.org/10.3390/ijerph18168648.
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In 2015, the resettlement of 25,000 Syrian refugees in Canada placed a strain on social services. Caseworkers employed in these agencies often come from similar migratory trajectories to those of the refugees. This experiential proximity requires an understanding of the subjective perspectives that caseworkers with migratory paths have of refugees in the context of their professional practice. We analyzed fifteen individual interviews with Canadian caseworkers and conducted field observations of resettlement activities in the Ottawa-Gatineau region using inductive reasoning inspired by grounded theory. Adopting a sociogenetic approach to social representation theory, this qualitative study illustrates how the social representation of refugees among foreign-born caseworkers is highly informed by their migratory past experience, as well as by the social identity and social context from which that representation was socio-generated. Our analysis reveals the mirror effect of the caseworkers as a fruitful concept for understanding the identity-otherness dynamics in the encounter between the distant other (refugee) and the self.
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Hall, Chris M., and Magnar G. Johnsen. "Possible influence of variations in the geomagnetic field on migration paths of snow buntings." International Journal of Astrobiology 19, no. 2 (2019): 195–201. http://dx.doi.org/10.1017/s1473550419000193.
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AbstractA hypothesis is proposed wherein changes in the Earth's magnetic field affect the migratory paths of snow buntings (Plectrophenax nivalis), and in particular from wintering grounds in the Russian/Ukrainian steppes to breeding grounds on Svalbard and with a typical stopover in Finnmark in northern Norway. If one were to assume ignorance of the secular movement of the magnetic north pole approximately 1500 km northwards between 1908 and 2020, the magnetoreceptor contribution to snow buntings' navigation would result in winter-to-summer migratory paths progressively further to the East. In turn, this could be a contributing factor to declining populations in Finnmark and favouring a more frequent flightpath over the Kola Peninsula. On the other hand, short-term perturbations in the magnetic field (i.e. induced by solar activity) and therefore existing for a relatively small proportion of the flight time (if at all) for the individual migrations legs seem unlikely to influence the stopover locations significantly. Even so, these space-weather induced variations cannot be disregarded, particularly for success in reaching Svalbard.
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Leber, SM, and JR Sanes. "Migratory paths of neurons and glia in the embryonic chick spinal cord." Journal of Neuroscience 15, no. 2 (1995): 1236–48. http://dx.doi.org/10.1523/jneurosci.15-02-01236.1995.
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Thorup, Kasper, Mark Fuller, Thomas Alerstam, Mikael Hake, Nils Kjellén, and Roine Strandberg. "Do migratory flight paths of raptors follow constant geographical or geomagnetic courses?" Animal Behaviour 72, no. 4 (2006): 875–80. http://dx.doi.org/10.1016/j.anbehav.2006.01.028.
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Pagel, R. Kyle, Elena H. West, Andrew W. Jones, and Henry M. Streby. "Variation in individual autumn migration and winter paths of Great Lakes red-headed woodpeckers (Melanerpes erythrocephalus)." Animal Migration 7, no. 1 (2020): 9–18. http://dx.doi.org/10.1515/ami-2020-0002.
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AbstractMigratory movements of facultative migrants are poorly understood due to their irregular and often unpredictable occurrence. However, tracking such movements is important for understanding population dynamics, informing annual cycle conservation plans, and identifying possible cues of facultative migration. We used pinpoint GPS tags to track autumn and winter movements of migratory red-headed woodpeckers (Melanerpes erythrocephalus) to better understand migration frequency, timing, and routes for birds breeding in managed oak savanna systems in the North American Great Lakes region. Proportions of individuals migrating differed between the two sites, with 72% of the Ohio population migrating, while no individuals in the Minnesota population migrated. Of the Ohio birds that migrated, their movements were highly variable in distance and direction but generally occurred south of the breeding site. Wintering sites ranged from 111 – 218 km from the breeding site. Cover types occupied during migration and wintering were almost exclusively small patches of closed-canopy hardwood forest within agricultural matrices. We documented one-time movements in migratory and non-migratory individuals during the year that have not previously been described in facultative migrants. We found no evidence of a harness or marker effect on proportions of individuals migrating, migration return rates, or annual survival regardless of migration.
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Crossin, G. T., S. G. Hinch, A. P. Farrell, M. P. Whelly, and M. C. Healey. "Pink salmon (Oncorhynchus gorbuscha) migratory energetics: response to migratory difficulty and comparisons with sockeye salmon (Oncorhynchus nerka)." Canadian Journal of Zoology 81, no. 12 (2003): 1986–95. http://dx.doi.org/10.1139/z03-193.
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Pink salmon (Oncorhynchus gorbuscha) are generally considered weak upriver migrants relative to sockeye salmon (Oncorhynchus nerka), though this assertion is largely anecdotal. To assess energy-use patterns during migration, we collected pink salmon from two major Fraser River stocks (Weaver and Seton in British Columbia, Canada) in 1999 at three times and locations: (1) at the start of freshwater migration, (2) at the end of migration before spawning, and (3) immediately after spawning. We calculated the energy content of somatic and reproductive tissues, recorded several body measurements, and conducted both intraspecific (between pink stocks) and interspecific analyses with co-migrating Fraser River sockeye salmon collected during the same season. We found that between pink salmon stocks, there were no significant energetic or morphological differences either at river entry or upon arrival at spawning areas regardless of the level of migratory difficulty encountered. When compared with sockeye salmon, however, we found that pink salmon began upriver migration with significantly smaller somatic energy reserves but made up for this deficiency by minimizing absolute transport and activity costs, presumably by seeking out migratory paths of least resistance. This energetic efficiency comes at a cost to reproductive output: relative to sockeye salmon, pink salmon diverted less absolute energy to egg production, producing smaller ovaries and fewer eggs. We speculate that fundamental differences in behaviour shape the migratory energetic tactics employed by pink salmon.
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De Laere, Maxime, Zwi N. Berneman, and Nathalie Cools. "To the Brain and Back: Migratory Paths of Dendritic Cells in Multiple Sclerosis." Journal of Neuropathology & Experimental Neurology 77, no. 3 (2018): 178–92. http://dx.doi.org/10.1093/jnen/nlx114.
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Slemrod, Joel. "Comments on “The Flight Paths of Migratory Corporations” by James R. Hines, Jr." Journal of Accounting, Auditing & Finance 6, no. 4 (1991): 480–85. http://dx.doi.org/10.1177/0148558x9100600405.
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Helweg, David, Peter Jenkins, Douglas Cat, Robert McCauley, and Claire Garrigue. "Geograpmc Variation in South Pacific Humpback Whale Songs." Behaviour 135, no. 1 (1998): 1–27. http://dx.doi.org/10.1163/156853998793066438.
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AbstractEvery winter, (male) humpback whales (Megaptera novaeangliae) produce long complex songs. Song content is dynamic and singers incorporate changes as they occur, thus song is shared through cultural transmission. We compared songs recorded in winter migratory termini in Tonga, New Caledonia, Eastern Australia, and on migration paths off Eastern Australia and New Zealand, in the winter of 1994. Seven themes were shared by all regions, with an additional two themes shared by all but Tonga. Differences in regional variants were most pronounced between Tongan and Eastern Australian song. New Caledonian and Kaikouran song were more similar to songs from Eastern Australia rather than Tonga. These regional differences were stable across the season. The results suggest some migratory exchange among widely separate wintering regions of Area V, consistent with tag recovery data, but the time and location at which song sharing occurs remains speculative.
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Lorente-Cánovas, Beatriz, Faustino Marín, Rubén Corral-San-Miguel, et al. "Multiple origins, migratory paths and molecular profiles of cells populating the avian interpeduncular nucleus." Developmental Biology 361, no. 1 (2012): 12–26. http://dx.doi.org/10.1016/j.ydbio.2011.09.032.
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Gray, Grace E., and Joshua R. Sanes. "Migratory paths and phenotypic choices of clonally related cells in the avian optic tectum." Neuron 6, no. 2 (1991): 211–25. http://dx.doi.org/10.1016/0896-6273(91)90357-6.
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Zhang, Gang, Dany Shoham, David Gilichinsky, Sergei Davydov, John D. Castello, and Scott O. Rogers. "Evidence of Influenza A Virus RNA in Siberian Lake Ice." Journal of Virology 80, no. 24 (2006): 12229–35. http://dx.doi.org/10.1128/jvi.00986-06.
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ABSTRACT Influenza A virus infects a large proportion of the human population annually, sometimes leading to the deaths of millions. The biotic cycles of infection are well characterized in the literature, including in studies of populations of humans, poultry, swine, and migratory waterfowl. However, there are few studies of abiotic reservoirs for this virus. Here, we report the preservation of influenza A virus genes in ice and water from high-latitude lakes that are visited by large numbers of migratory birds. The lakes are along the migratory flight paths of birds flying into Asia, North America, Europe, and Africa. The data suggest that influenza A virus, deposited as the birds begin their autumn migration, can be preserved in lake ice. As birds return in the spring, the ice melts, releasing the viruses. Therefore, temporal gene flow is facilitated between the viruses shed during the previous year and the viruses newly acquired by birds during winter months spent in the south. Above the Arctic Circle, the cycles of entrapment in the ice and release by melting can be variable in length, because some ice persists for several years, decades, or longer. This type of temporal gene flow might be a feature common to viruses that can survive entrapment in environmental ice and snow.
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Pourette, Dolorès. "Migratory Paths, Experiences of HIV/AIDS, and Sexuality: African Women Living withHIV/AIDS in France." Feminist Economics 14, no. 4 (2008): 149–81. http://dx.doi.org/10.1080/13545700802262949.
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Garrigue, Claire, Phillip J. Clapham, Ygor Geyer, Amy S. Kennedy, and Alexandre N. Zerbini. "Satellite tracking reveals novel migratory patterns and the importance of seamounts for endangered South Pacific humpback whales." Royal Society Open Science 2, no. 11 (2015): 150489. http://dx.doi.org/10.1098/rsos.150489.
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The humpback whale population of New Caledonia appears to display a novel migratory pattern characterized by multiple directions, long migratory paths and frequent pauses over seamounts and other shallow geographical features. Using satellite-monitored radio tags, we tracked 34 whales for between 5 and 110 days, travelling between 270 and 8540 km on their southward migration from a breeding ground in southern New Caledonia. Mean migration speed was 3.53±2.22 km h −1 , while movements within the breeding ground averaged 2.01±1.63 km h −1 . The tag data demonstrate that seamounts play an important role as offshore habitats for this species. Whales displayed an intensive use of oceanic seamounts both in the breeding season and on migration. Seamounts probably serve multiple and important roles as breeding locations, resting areas, navigational landmarks or even supplemental feeding grounds for this species, which can be viewed as a transient component of the seamount communities. Satellite telemetry suggests that seamounts represent an overlooked cryptic habitat for the species. The frequent use by humpback whales of such remote locations has important implications for conservation and management.
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Touzot, Audrey, Nuria Ruiz-Reig, Tania Vitalis, and Michèle Studer. "Molecular control of two novel migratory paths for CGE-derived interneurons in the developing mouse brain." Development 143, no. 10 (2016): 1753–65. http://dx.doi.org/10.1242/dev.131102.
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ElDahshan, K., E. K. Elsayed, and H. Mancy. "Semantic Smart World Framework." Applied Computational Intelligence and Soft Computing 2020 (January 20, 2020): 1–12. http://dx.doi.org/10.1155/2020/8081578.
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This paper presents a general Semantic Smart World framework (SSWF), to cover the Migratory birds’ paths. This framework combines semantic and big data technologies to support meaning for big data. In order to build the proposed smart world framework, technologies such as cloud computing, semantic technology, big data, data visualization, and the Internet of Things are hybrid. We demonstrate the proposed framework through a case study of automatic prediction of air quality index and different weather phenomena in the different locations in the world. We discover the association between air pollution and increasing weather conditions. The experimental results indicate that the framework performance is suitable for heterogeneous big data.
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Li, Hao, Shen-Ju Chou, Tadashi Hamasaki, Carlos G. Perez-Garcia, and Dennis DM O'Leary. "Neuregulin repellent signaling via ErbB4 restricts GABAergic interneurons to migratory paths from ganglionic eminence to cortical destinations." Neural Development 7, no. 1 (2012): 10. http://dx.doi.org/10.1186/1749-8104-7-10.
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YONG, DING LI, YANG LIU, BING WEN LOW, CARMELA P. ESPAÑOLA, CHANG-YONG CHOI, and KAZUTO KAWAKAMI. "Migratory songbirds in the East Asian-Australasian Flyway: a review from a conservation perspective." Bird Conservation International 25, no. 1 (2015): 1–37. http://dx.doi.org/10.1017/s0959270914000276.
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SummaryThe East Asian-Australasian Flyway supports the greatest diversity and populations of migratory birds globally, as well as the highest number of threatened migratory species of any flyway, including passerines (15 species). However it is also one of the most poorly understood migration systems, and little is known about the populations and ecology of the passerine migrants that breed, stop over and winter in the habitats along this flyway. We provide the first flyway-wide review of diversity, ecology, and conservation issues relating to 170 species of long-distance and over 80 short-distance migrants from 32 families. Recent studies of songbird migration movements and ecology is limited, and is skewed towards East Asia, particularly Mainland China, Taiwan, Russia, Japan and South Korea. Strong evidence of declines exists for some species, e.g. Yellow-breasted Bunting Emberiza aureola, but tends to be fragmentary, localised or anecdotal for many others. More species have small breeding ranges (< 250,000 km2) and/or are dependent on tropical forests as wintering habitat than those in any other Eurasian migratory system, and are thus more vulnerable to habitat loss and degradation throughout their ranges. Poorly regulated hunting for food and the pet trade, invasive species and collisions with man-made structures further threaten migratory songbirds at a number of stop-over or wintering sites, while climate change and habitat loss may be of increasing concern in the breeding ranges. A key conservation priority is to carry out intensive field surveys across the region while simultaneously tapping into citizen science datasets, to identify important stop-over and wintering sites, particularly for poorly-known or globally threatened species across South-East Asia and southern China for targeted conservation actions. Additionally, the advent of miniaturised tracking technology, molecular and isotopic techniques can provide novel insights into migration connectivity, paths and ecology for species in this migration system, complementing data from banding exercises and observation-based surveys, and could prove useful in informing conservation priorities. However, until most states along the East Asian-Australasian flyway ratify the Convention on the Conservation of Migratory Species of Wild Animals (CMS) and other cross-boundary treaties, the relative lack of cross-boundary cooperation, coordination and information sharing in the region will continue to present a stumbling block for effective conservation of migratory passerines.
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Szabó, András, and Roberto Mayor. "Mechanisms of Neural Crest Migration." Annual Review of Genetics 52, no. 1 (2018): 43–63. http://dx.doi.org/10.1146/annurev-genet-120417-031559.
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Neural crest cells are a transient embryonic cell population that migrate collectively to various locations throughout the embryo to contribute a number of cell types to several organs. After induction, the neural crest delaminates and undergoes an epithelial-to-mesenchymal transition before migrating through intricate yet characteristic paths. The neural crest exhibits a variety of migratory behaviors ranging from sheet-like mass migration in the cephalic regions to chain migration in the trunk. During their journey, neural crest cells rely on a range of signals both from their environment and within the migrating population for navigating through the embryo as a collective. Here we review these interactions and mechanisms, including chemotactic cues of neural crest cells’ migration.
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Biddlecombe, BA, EM Bayne, NJ Lunn, D. McGeachy, and AE Derocher. "Effects of sea ice fragmentation on polar bear migratory movement in Hudson Bay." Marine Ecology Progress Series 666 (May 20, 2021): 231–41. http://dx.doi.org/10.3354/meps13684.
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Habitat fragmentation can impede an animal’s ability to move through their habitat, affecting both local and long-distance movements. Each year, polar bears Ursus maritimus migrate to refuge habitats on land or to multiyear ice as annual sea ice breaks up. We used polar bear telemetry location data from 39 adult female polar bears tracked in Hudson Bay in 2013-2018 during break-up (2 May-23 July) to show variation in migratory movement and timing as break-up advances. We separated break-up into early and late periods and used standard deviation in temporal spatial autocorrelation (SASD) of sea ice concentration to quantify sea ice fragmentation. Higher spatial autocorrelation reflects dissimilarity in local habitat composition at a single point in time, while SASD reflects variation in local habitat composition over time. In late break-up, there was a significant positive correlation between polar bear path tortuosity and SASD. Individuals arrived on land significantly later when paths moved through sea ice with increasing SASD in late break-up. Reproductive status of adult female polar bears had no effect on the variability of the sea ice an individual travelled through. SASD provides a means of summarizing the complexity and dynamics of sea ice habitat and can be used to understand variation in movement and ecology of ice-associated organisms.
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Thorsen, Dorte. "Is Europe really the dream? Contingent paths among sub-Saharan migrants in Morocco." Africa 87, no. 2 (2017): 343–61. http://dx.doi.org/10.1017/s0001972016000991.
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AbstractThis article explores migrant existences in the border zones around Europe. Drawing on ethnographic research in Morocco undertaken in 2012, 2013 and 2015 and in continued engagements with migrants using social media, the article analyses three extended migrant stories, detailing their experiences of uncertainty, waiting and hoping. By elucidating the objectives informing migrants’ pathways and the material and moral considerations underpinning the ways in which they navigate migrant life in Rabat, the stories unveil how different temporalities and spatialities intersect and influence their decisions and ability to endure hardship and waiting. The article argues that uncertainties and risks inherent in migration, and in irregular migration in particular, have transformed collective expectations of the migratory project as a means of upward social mobility and economic security into hope and into a mode of hoping that individualizes success and failure. Meanwhile, the rising costs of migration and structural marginalization render the opportunity to travel elsewhere contingent on assistance from transnational social networks or international institutions. Individuals’ success or failure thus comes to depend on how understandings of hardship, waiting, opportunity and moral obligation are configured and reconfigured by lived experiences in different places.
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Edgar, Lowell T., Claudio A. Franco, Holger Gerhardt, and Miguel O. Bernabeu. "On the preservation of vessel bifurcations during flow-mediated angiogenic remodelling." PLOS Computational Biology 17, no. 2 (2021): e1007715. http://dx.doi.org/10.1371/journal.pcbi.1007715.
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During developmental angiogenesis, endothelial cells respond to shear stress by migrating and remodelling the initially hyperbranched plexus, removing certain vessels whilst maintaining others. In this study, we argue that the key regulator of vessel preservation is cell decision behaviour at bifurcations. At flow-convergent bifurcations where migration paths diverge, cells must finely tune migration along both possible paths if the bifurcation is to persist. Experiments have demonstrated that disrupting the cells’ ability to sense shear or the junction forces transmitted between cells impacts the preservation of bifurcations during the remodelling process. However, how these migratory cues integrate during cell decision making remains poorly understood. Therefore, we present the first agent-based model of endothelial cell flow-mediated migration suitable for interrogating the mechanisms behind bifurcation stability. The model simulates flow in a bifurcated vessel network composed of agents representing endothelial cells arranged into a lumen which migrate against flow. Upon approaching a bifurcation where more than one migration path exists, agents refer to a stochastic bifurcation rule which models the decision cells make as a combination of flow-based and collective-based migratory cues. With this rule, cells favour branches with relatively larger shear stress or cell number. We found that cells must integrate both cues nearly equally to maximise bifurcation stability. In simulations with stable bifurcations, we found competitive oscillations between flow and collective cues, and simulations that lost the bifurcation were unable to maintain these oscillations. The competition between these two cues is haemodynamic in origin, and demonstrates that a natural defence against bifurcation loss during remodelling exists: as vessel lumens narrow due to cell efflux, resistance to flow and shear stress increases, attracting new cells to enter and rescue the vessel from regression. Our work provides theoretical insight into the role of junction force transmission has in stabilising vasculature during remodelling and as an emergent mechanism to avoid functional shunting.
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Beauvais, A., C. A. Erickson, T. Goins, et al. "Changes in the fibronectin-specific integrin expression pattern modify the migratory behavior of sarcoma S180 cells in vitro and in the embryonic environment." Journal of Cell Biology 128, no. 4 (1995): 699–713. http://dx.doi.org/10.1083/jcb.128.4.699.
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The molecules that mediate cell-matrix recognition, such as fibronectins (FN) and integrins, modulate cell behavior. We have previously demonstrated that FN and the beta 1-integrins are used during neural crest cell (NCC) migration in vitro as well as in vivo, and that the FN cell-binding domains I and II exhibit functional specificity in controlling either NCC attachment, spreading, or motility in vitro. In the present study, we have analyzed the effect of changes in the integrin expression patterns on migratory cell behavior in vivo. We have generated, after stable transfection, S180 cells expressing different levels of alpha 4 beta 1 or alpha 5 beta 1 integrins, two integrins that recognize distinct FN cell-binding domains. Murine S180 cells were chosen because they behave similarly to NCC after they are grafted into the NCC embryonic pathways in the chicken embryo. Thus, they provide a model system with which to investigate the mechanisms controlling in vitro and in vivo migratory cell behavior. We have observed that either the overexpression of alpha 5 beta 1 integrin or the induction of alpha 4 beta 1 expression in transfected S180 cells enhances their motility on FN in vitro. These genetically modified S180 cells also exhibit different migratory properties when grafted into the early trunk NCC migratory pathways. We observe that alpha 5 and low alpha 4 expressors migrate in both the ventral and dorsolateral paths simultaneously, in contrast to the parental S180 cells or the host NCC, which are delayed by 24 h in their invasion of the dorsolateral path. Moreover, the alpha 4 expressors exhibit different migratory properties according to their level of alpha 4 expression at the cell surface. Cells of the low alpha 4 expressor line invade both the ventral and dorsolateral pathways. In contrast, the high expressors remain as an aggregate at the graft site, possibly the result of alpha 4 beta 1-dependent homotypic aggregation. Thus, changes in the repertoire of FN-specific integrins enable the S180 cells to exploit different pathways in the embryo and regulate the speed with which they disperse in vivo and in culture. Our studies correlate well with known changes in integrin expression during neural crest morphogenesis and strongly suggest that neural crest cells that migrate into the dorsolateral path, i.e., melanoblasts, do so only after they have upregulated the expression of FN receptors.(ABSTRACT TRUNCATED AT 400 WORDS)
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Tweedy, Luke, Peter A. Thomason, Peggy I. Paschke, et al. "Seeing around corners: Cells solve mazes and respond at a distance using attractant breakdown." Science 369, no. 6507 (2020): eaay9792. http://dx.doi.org/10.1126/science.aay9792.
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During development and metastasis, cells migrate large distances through complex environments. Migration is often guided by chemotaxis, but simple chemoattractant gradients between a source and sink cannot direct cells over such ranges. We describe how self-generated gradients, created by cells locally degrading attractant, allow single cells to navigate long, tortuous paths and make accurate choices between live channels and dead ends. This allows cells to solve complex mazes efficiently. Cells’ accuracy at finding live channels was determined by attractant diffusivity, cell speed, and path complexity. Manipulating these parameters directed cells in mathematically predictable ways; specific combinations can even actively misdirect them. We propose that the length and complexity of many long-range migratory processes, including inflammation and germ cell migration, means that self-generated gradients are needed for successful navigation.
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Hucke-Gaete, Rodrigo, Luis Bedriñana-Romano, Francisco A. Viddi, Jorge E. Ruiz, Juan Pablo Torres-Florez, and Alexandre N. Zerbini. "From Chilean Patagonia to Galapagos, Ecuador: novel insights on blue whale migratory pathways along the Eastern South Pacific." PeerJ 6 (April 30, 2018): e4695. http://dx.doi.org/10.7717/peerj.4695.
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Background The most traditional scheme for migration among baleen whales comprises yearly migrations between productive waters at high latitude summer feeding grounds and warmer waters at lower latitudes where whales calve and mate, but rarely feed. Evidence indicates, however, that large departures from this scheme exist among populations and individuals. Furthermore, for some populations there is virtually no information on migratory pathways and destinations. Such is the case of Chilean blue whales throughout the Eastern South Pacific; hence, the goal of this study was to assess its migratory behavior. Methods Dedicated marine surveys and satellite tagging efforts were undertaken during the austral summer and early autumn on blue whale feeding grounds off Chilean Northern Patagonia (CNP) during 2013, 2015 and 2016. Positional data derived from satellite tags regarding movement patterns and behavior were analyzed using Bayesian switching first-difference correlated random walk models. Results We instrumented 10 CNP blue whales with satellite transmitters and documented individual variation in departure time, northbound migratory routes and potential wintering grounds. The onset of migration occurred from mid/late austral autumn to well into the austral winter. Blue whales moved in various directions, but ultimately converged toward a general NW movement direction along a wide corridor exceeding 2,000 km. Area-Restricted Search behavior was exhibited within fjords and channels of CNP and also South of Galapagos Archipelago (GA) and northern Peru, but never during migration. Interestingly, dive profiles for one whale that reached GA showed a sharp and consistent increase in depth north of 5°S and extreme deep dives of up to 330 m. Discussion Information derived from satellite tagged blue whales in this study is the first of its kind off the Eastern Southern Pacific. Our results provide valuable information on their migratory timing, routes and behavior on their northbound migration, particularly regarding the varied migratory plasticity for this particular population. Our results also highlight the first record of two complete migratory paths between CNP and GA and strengthen the hypothesis that GA waters correspond to a potential wintering destination for CNP blue whales. We further hypothesize that this area might be selected because of its biological productivity, which could provide feeding opportunities during the breeding season. Our results suggest that special efforts should be put forward to identify blue whale critical areas and understand key behavioral aspects in order to provide the basis for their conservation on a regional context (i.e., reducing potential ship strike and promote Marine Protected Area (MPA) implementation in Chile, Ecuador and Peru). Indeed, we suggest joint blue whale conservation efforts at the regional level in order to identify and determine potential threats and impacts and, most importantly, implement prospective management actions.
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Seo, Je Hoon, Jae Hyuk Chang, Seon Hwa Song, et al. "Spatiotemporal Gradient of Astrocyte Development in the Chick Optic Tectum: Evidence for Multiple Origins and Migratory Paths of Astrocytes." Neurochemical Research 33, no. 7 (2008): 1346–55. http://dx.doi.org/10.1007/s11064-008-9590-3.
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KIRSCHVINK, JOSEPH L., ANDREW E. DIZON, and JAMES A. WESTPHAL. "Evidence from Strandings for Geomagnetic Sensitivity in Cetaceans." Journal of Experimental Biology 120, no. 1 (1986): 1–24. http://dx.doi.org/10.1242/jeb.120.1.1.
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We tested the hypothesis that cetaceans use weak anomalies in the geomagnetic field as cues for orientation, navigation and/or piloting. Using the positions of 212 stranding events of live animals in the Smith sonian compilation which fall within the boundaries of the USGS East-Coast Aeromagnetic Survey, we found that there are highly significant tendencies for cetaceans to beach themselves near coastal locations with local magnetic minima. Monte-Carlo simulations confirm the significance of these effects. These results suggest that cetaceans have a magnetic sensory systemcomparable to that in other migratory and homing animals, and predict that the magnetic topography and in particular the marine magnetic lineations may play an important role in guiding long-distance migration. The ‘map’ sense of migratoryanimals may therefore be largely based on a simple strategy of following paths of local magnetic minima and avoiding magnetic gradients.
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Roth, Timothy C., and Aaron R. Krochmal. "Of molecules, memories and migration: M1 acetylcholine receptors facilitate spatial memory formation and recall during migratory navigation." Proceedings of the Royal Society B: Biological Sciences 285, no. 1891 (2018): 20181904. http://dx.doi.org/10.1098/rspb.2018.1904.
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Many animals use complex cognitive processes, including the formation and recall of memories, for successful navigation. However, the developmental and neurological processes underlying these cognitive aspects of navigation are poorly understood. To address the importance of the formation and recollection of memories during navigation, we pharmacologically manipulated turtles ( Chrysemys picta ) that navigate long distances using precise, complex paths learned during a juvenile critical period. We treated freely navigating turtles both within and outside of their critical learning period with a specific M1 acetylcholine receptor antagonist, a drug known to disrupt spatial cognition. Experienced adult turtles lost all navigational ability under the influence of the drug, while naive juveniles navigated successfully. We retested these same juveniles the following year (after they had passed their critical period). The juveniles that initially navigated successfully under the influence of the antagonist (but were unable to form spatial memories) were unable to do so subsequently. However, the control animals (who had the opportunity to form memories previously) exhibited typical navigational precision. These results suggest that the formation of spatial memories for navigation occur during a critical period, and successful navigation after the critical period is dependent upon the recall of such memories.
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François, Joshua, Adithan Kandasamy, Yi-Ting Yeh, et al. "The interplay between matrix deformation and the coordination of turning events governs directed neutrophil migration in 3D matrices." Science Advances 7, no. 29 (2021): eabf3882. http://dx.doi.org/10.1126/sciadv.abf3882.
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Neutrophils migrating through extravascular spaces must negotiate narrow matrix pores without losing directional movement. We investigated how chemotaxing neutrophils probe matrices and adjust their migration to collagen concentration ([col]) changes by tracking 20,000 cell trajectories and quantifying cell-generated 3D matrix deformations. In low-[col] matrices, neutrophils exerted large deformations and followed straight trajectories. As [col] increased, matrix deformations decreased, and neutrophils turned often to circumvent rather than remodel matrix pores. Inhibiting protrusive or contractile forces shifted this transition to lower [col], implying that mechanics play a crucial role in defining migratory strategies. To balance frequent turning and directional bias, neutrophils used matrix obstacles as pivoting points to steer toward the chemoattractant. The Actin Related Protein 2/3 complex coordinated successive turns, thus controlling deviations from chemotactic paths. These results offer an improved understanding of the mechanisms and molecular regulators used by neutrophils during chemotaxis in restrictive 3D environments.
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Hu, G., M. H. Lu, H. A. Tuan, et al. "Population dynamics of rice planthoppers, Nilaparvata lugens and Sogatella furcifera (Hemiptera, Delphacidae) in Central Vietnam and its effects on their spring migration to China." Bulletin of Entomological Research 107, no. 3 (2016): 369–81. http://dx.doi.org/10.1017/s0007485316001024.
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AbstractRice planthopper (RPH) populations of Nilaparvata lugens and Sogatella furcifera periodically have erupted across Asia. Predicting RPH population dynamics and identifying their source areas are crucial for the management of these migratory pests in China, but the origins of the migrants to temperate and subtropical regions in China remains unclear. In particular, their early migration to China in March and April have not yet been explored due to a lack of research data available from potential source areas, Central Vietnam and Laos. In this study, we examined the population dynamics and migratory paths of N. lugens and S. furcifera in Vietnam and South China in 2012 and 2013. Trajectory modeling showed that in March and April in 2012 and 2013, RPH emigrated from source areas in Central Vietnam where rice was maturing to the Red River Delta and South China. Early migrants originated from Southern Central Vietnam (14–16°N), but later most were from Northern Central Vietnam (16–19°N). Analysis of meteorological and light-trap data from Hepu in April (1977–2013) using generalized linear models showed that immigration increased with precipitation in Southern Central Vietnam in January, but declined with precipitation in Northern Central Vietnam in January. These results determined that the RPH originate from overwintering areas in Central Vietnam, but not from southernmost areas of Vietnam. Winter precipitation, rather than temperature was the most important factor determining the number of RPH migrants. Based on their similar population dynamics and low population densities in Central Vietnam, we further speculated that RPH migrate to track ephemeral food resources whilst simultaneously avoiding predators. Migrations do not seem to be initiated by interspecific competition, overcrowding or host deterioration. Nevertheless, S. furcifera establishes populations earlier than N. lugens South China, perhaps to compensate for interspecific competition. We provide new information that could assist with forecasting outbreaks and implementing control measures against these migratory pests.
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Sinsch, Ulrich. "Movement ecology of amphibians: from individual migratory behaviour to spatially structured populations in heterogeneous landscapes,." Canadian Journal of Zoology 92, no. 6 (2014): 491–502. http://dx.doi.org/10.1139/cjz-2013-0028.
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Both genetic cohesion among local populations of animals and range expansion depend on the frequency of dispersers moving at an interpatch scale. Animal movement has an individual component that reflects behaviour and an ecological component that reflects the spatial organization of populations. The total movement capacity of an individual describes maximum movement distance theoretically achievable during a lifetime, whereas its variation among the members of a local population determines the magnitude of interpatch movements and thus of gene flow between neighbouring patches within metapopulation or patchy population systems. Here, I review information on dispersal and migration as components of the movement capacity of juvenile and adult pond-breeding amphibians and discuss how these components inform the spatial structure of populations. Amphibians disperse as juveniles and adults, but movement distances detected in tracking or capture–mark–recapture studies are usually far below the corresponding estimates based on molecular gene-flow data. This discrepancy reflects the constraints of available tracking methods for free-ranging individuals leading to inappropriate surrogates of annual movement capacity, but can be resolved using probabilistic approaches based on dispersal functions. There is remarkable capacity for and plasticity in movements in amphibians. Annual within-patch movements (migrations) of individuals can be large and likely represent an underestimated capacity for movement at the interpatch scale. Landscape resistance may influence the paths of dispersing amphibians, but rarely impedes interpatch movements. Juveniles emigrating unpredictably far from the natal pond and adults switching from within-patch migrations to dispersal to another patch demonstrate the plasticity of individual movement behaviour. Three basic conclusions can be drawn with respect to the linkage of individual movement behaviour and spatial or genetic structure of local amphibian populations embedded in a heterogeneous landscape: (1) individual movements or consecutive short-term series of movements are misleading surrogate measures of total movement capacity; (2) probabilistic modelling of movement capacity is the best available behavioural predictor of interpatch gene flow; (3) connectivity of local populations in heterogeneous landscapes is less affected by landscape resistance than previously expected.
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Ricucci, Roberta. "In the Shadow of Bell Towers: The Use of Religious Capital among Christian-Catholic Second Generations in Italy." Social Inclusion 4, no. 2 (2016): 87–94. http://dx.doi.org/10.17645/si.v4i2.496.
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Evidence from some contemporary ethnic groups suggests that ethnic religion may play a strong role in the lives of second generation members. This is evident in recent studies on Muslims living in Europe. But Europe's immigrant population is not just Muslim in origin. Migratory flows from Latin America, the Philippines and Eastern Europe (i.e. Romania or Ukraine) bring people from Catholic and Christian countries to Europe. And—as in the Italian case—these groups are now the majority among the whole immigrant population. Consequently, the almost exclusive focus on the Islamic component has allowed little investigation of the increase of the Christian-Catholic component. The paper describes and compares the religious paths of immigrants’ youth from Peru, the Philippines and Romania, considering the following questions: How do they interact with/develop their religious identity? Is this generation seeking less visible, less participatory means of contact with the church to better integrate with their peers? Or, on the contrary, do they choose, strategically, to reinforce the Catholic part of their identity in order to succeed better in the integration process in a Catholic country?
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Sano, Hiroko, Andrew D. Renault, and Ruth Lehmann. "Control of lateral migration and germ cell elimination by the Drosophila melanogaster lipid phosphate phosphatases Wunen and Wunen 2." Journal of Cell Biology 171, no. 4 (2005): 675–83. http://dx.doi.org/10.1083/jcb.200506038.
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In most organisms, primordial germ cells (PGCs) arise far from the region where somatic gonadal precursors (SGPs) are specified. Although PGCs in general originate as a single cluster of cells, the somatic parts of the gonad form on each site of the embryo. Thus, to reach the gonad, PGCs not only migrate from their site of origin but also split into two groups. Taking advantage of high-resolution real-time imaging, we show that in Drosophila melanogaster PGCs are polarized and migrate directionally toward the SGPs, avoiding the midline. Unexpectedly, neither PGC attractants synthesized in the SGPs nor known midline repellents for axon guidance were required to sort PGCs bilaterally. Repellent activity provided by wunen (wun) and wunen-2 (wun-2) expressed in the central nervous system, however, is essential in this migration process and controls PGC survival. Our results suggest that expression of wun/wun-2 repellents along the migratory paths provides faithful control over the sorting of PGCs into two gonads and eliminates PGCs left in the middle of the embryo.
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Tepass, U., L. I. Fessler, A. Aziz, and V. Hartenstein. "Embryonic origin of hemocytes and their relationship to cell death in Drosophila." Development 120, no. 7 (1994): 1829–37. http://dx.doi.org/10.1242/dev.120.7.1829.
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We have studied the embryonic development of Drosophila hemocytes and their conversion into macrophages. Hemocytes derive exclusively from the mesoderm of the head and disperse along several invariant migratory paths throughout the embryo. The origin of hemocytes from the head mesoderm is further supported by the finding that in Bicaudal D, a mutation that lacks all head structures, and in twist snail double mutants, where no mesoderm develops, hemocytes do not form. All embryonic hemocytes behave like a homogenous population with respect to their potential for phagocytosis. Thus, in the wild type, about 80–90% of hemocytes become macrophages during late development. In mutations with an increased amount of cell death (knirps; stardust; fork head), this figure approaches 100%. In contrast, in these mutations, the absolute number of hemocytes does not differ from that in wild type, indicating that cell death does not ‘induce’ the formation of hemocytes. Finally, we show that, in the Drosophila embryo, apoptosis can occur independently of macrophages, since mutations lacking macrophages (Bicaudal D; twist snail double mutants; torso4021) show abundant cell death.
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Béguer-Pon, Mélanie, Shiliang Shan, Keith R. Thompson, Martin Castonguay, Jinyu Sheng, and Julian J. Dodson. "Exploring the role of the physical marine environment in silver eel migrations using a biophysical particle tracking model." ICES Journal of Marine Science 73, no. 1 (2015): 57–74. http://dx.doi.org/10.1093/icesjms/fsv169.
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Abstract Both the American eel (Anguilla rostrata) and European eel (Anguilla anguilla) undertake long-distance migrations from continental waters to their spawning sites in the Sargasso Sea. Their migration routes and orientation mechanisms remain a mystery. A biophysical particle tracking model was used in this study to simulate their oceanic migration from two release areas: off the Scotian Shelf (Canada) and off the Irish continental shelf. Two plausible swimming-directed behaviours were considered for simulating two different migratory paths: true navigation to specific spawning sites and innate compass orientation towards the vast spawning area. Several combinations of swimming speeds and depths were tested to assess the effect of ocean circulation on resulting migratory pathways of virtual eels (v-eels), environmental conditions experienced along their oceanic migration, and energy consumption. Simulations show that the spawning area can be reached in time by constantly swimming and following a readjusted heading (true navigation) or a constant heading (compass orientation) even at the lowest swimming speed tested (0.2 m s−1) for most v-eels. True navigation might not be necessary to reach the spawning area. The ocean currents affect mainly the migration of American v-eels, particularly for swimming speeds lower than 0.8 m s−1. The ocean circulation increases the variability in the oceanic migration and generally reduces the efficiency of the v-eels, although positive effects can be possible for certain individuals. The depth range of diel vertical migration (DVM) significantly affects the total energy expenditure due to the water temperature experienced at the various depths. Model results also suggest that energy would not be a limiting factor as v-eels constantly swimming at 0.8 BL s−1 spent &lt;25 and 42% of energy available for migration for American and European v-eels, respectively.
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Galijaš, Armina. "Permanently in Transit. Middle Eastern Migrants and Refugees in Serbia." Südosteuropa 67, no. 1 (2019): 75–109. http://dx.doi.org/10.1515/soeu-2019-0004.
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Abstract Serbia has never been the chosen final destination for refugees from Iraq, Syria, and other beleaguered countries like Afghanistan who have embarked on the so-called Balkan route since 2015. But following the closure of this route in March 2016, between 3,500 and 4,500 migrants have found themselves living in Serbia. This article analyses the composition and changing size of the migrant population, looking at the legal status of individuals and migratory paths taken. It moves on to examine reactions to the migrants from the state authorities and the Serbian public, together with the institutional response manifested in legal measures and infrastructural facilities, and the political contexts in which decisions about these were taken. Specific attention is given to the situation of refugee children who attend state schools in Serbia. The analysis reveals a pragmatic and quite flexible administrative response to the refugees’ situation. However, the remarkable level of tolerance is largely related to awareness that the great majority of those stranded in Serbia are doing everything in their power to continue their journey into central and northern Europe—that is to leave Serbia.
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Cottereau, Victoire. "Du parcours migratoire des professionnels de santé : une analyse de la présence des PADHUE en France (Migratory paths of health professionals : an analysis of the presence of foreign-trained doctors in France)." Bulletin de l'Association de géographes français 89, no. 2 (2012): 368–78. http://dx.doi.org/10.3406/bagf.2012.8275.
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Clay, Candice C., Denise S. Rodrigues, Danielle J. Harvey, Christian M. Leutenegger, and Ursula Esser. "Distinct Chemokine Triggers and In Vivo Migratory Paths of Fluorescein Dye-Labeled T Lymphocytes in Acutely Simian Immunodeficiency Virus SIVmac251-Infected and Uninfected Macaques." Journal of Virology 79, no. 21 (2005): 13759–68. http://dx.doi.org/10.1128/jvi.79.21.13759-13768.2005.
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ABSTRACT To define the possible impact of T-lymphocyte trafficking parameters on simian immunodeficiency virus (SIV) pathogenesis, we examined migratory profiles of carboxyfluorescein diacetate succinimidyl ester (CFSE)-labeled T lymphocytes in acutely SIVmac251-infected and uninfected macaques within 48 h after autologous transfer. Despite significant upregulation of homeostatic chemokine CCL19/macrophage inflammatory protein 3β and proinflammatory chemokine CXCL9/monokine induced by gamma interferon in secondary lymphoid tissue in SIV infection, no differences in CFSE+ T-lymphocyte frequencies or cell compartmentalization in lymph nodes were identified between animal groups. By contrast, a higher frequency of CFSE+ T lymphocytes in the small intestine was detected in acute SIV infection. This result correlated with increased numbers of gut CD4 T lymphocytes expressing chemokine receptors CCR9, CCR7, and CXCR3 and high levels of their respective chemokine ligands in the small intestine. The changes in trafficking parameters in SIV-infected macaques occurred concomitantly with acute gut CD4 T-lymphocyte depletion. Here, we present the first in vivo T-lymphocyte trafficking study in SIV infection and a novel approach to delineate T-lymphocyte recruitment into tissues in the nonhuman primate animal model for AIDS. Such studies are likely to provide unique insights into T-lymphocyte sequestration in distinct tissue compartments and possible mechanisms of CD4 T-lymphocyte depletion and immune dysfunction in simian AIDS.
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Selonen, Vesa, Samuli Helle, Toni Laaksonen, Markus P. Ahola, Esa Lehikoinen, and Tapio Eeva. "Identifying the paths of climate effects on population dynamics: dynamic and multilevel structural equation model around the annual cycle." Oecologia 195, no. 2 (2021): 525–38. http://dx.doi.org/10.1007/s00442-020-04817-3.
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AbstractHow environmental factors influence population dynamics in long-distance migrants is complicated by the spatiotemporal diversity of the environment the individuals experience during the annual cycle. The effects of weather on several different aspects of life history have been well studied, but a better understanding is needed on how weather affects population dynamics through the different associated traits. We utilise 77 years of data from pied flycatcher (Ficedula hypoleuca), to identify the most relevant climate signals associated with population growth rate. The strongest signals on population growth were observed from climate during periods when the birds were not present in the focal location. The population decline was associated with increasing precipitation in the African non-breeding quarters in the autumn (near the arrival of migrants) and with increasing winter temperature along the migration route (before migration). The number of fledglings was associated positively with increasing winter temperature in non-breeding area and negatively with increasing winter temperature in Europe. These possible carry-over effects did not arise via timing of breeding or clutch size but the exact mechanism remains to be revealed in future studies. High population density and low fledgling production were the intrinsic factors reducing the breeding population. We conclude that weather during all seasons has the potential to affect the reproductive success or population growth rate of this species. Our results show how weather can influence the population dynamics of a migratory species through multiple pathways, even at times of the annual cycle when the birds are in a different location than the climate signal.
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De Schrijver, Lotte, Tom Vander Beken, Barbara Krahé, and Ines Keygnaert. "Prevalence of Sexual Violence in Migrants, Applicants for International Protection, and Refugees in Europe: A Critical Interpretive Synthesis of the Evidence." International Journal of Environmental Research and Public Health 15, no. 9 (2018): 1979. http://dx.doi.org/10.3390/ijerph15091979.
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(1) Background: Sexual violence (SV) is a major public health problem, with negative socio-economic, physical, mental, sexual, and reproductive health consequences. Migrants, applicants for international protection, and refugees (MARs) are vulnerable to SV. Since many European countries are seeing high migratory pressure, the development of prevention strategies and care paths focusing on victimised MARs is highly needed. To this end, this study reviews evidence on the prevalence of SV among MAR groups in Europe and the challenges encountered in research on this topic. (2) Methods: A critical interpretive synthesis of 25 peer-reviewed academic studies and 22 relevant grey literature documents was conducted based on a socio-ecological model. (3) Results: Evidence shows that SV is highly frequent in MARs in Europe, yet comparison with other groups is still difficult. Methodologically and ethically sound representative studies comparing between populations are still lacking. Challenges in researching SV in MARs are located at the intrapersonal, interpersonal, community, societal, and policy levels. (4) Conclusions: Future research should start with a clear definition of the concerned population and acts of SV to generate comparable data. Participatory qualitative research approaches could be applied to better grasp the complexity of interplaying determinants of SV in MARs.
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Pullar, Christine E., Brian S. Baier, Yoshinobu Kariya та ін. "β4 Integrin and Epidermal Growth Factor Coordinately Regulate Electric Field-mediated Directional Migration via Rac1". Molecular Biology of the Cell 17, № 11 (2006): 4925–35. http://dx.doi.org/10.1091/mbc.e06-05-0433.
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Endogenous DC electric fields (EF) are present during embryogenesis and are generated in vivo upon wounding, providing guidance cues for directional cell migration (galvanotaxis) required in these processes. To understand the role of beta (β)4 integrin in directional migration, the migratory paths of either primary human keratinocytes (NHK), β4 integrin-null human keratinocytes (β4−), or those in which β4 integrin was reexpressed (β4+), were tracked during exposure to EFs of physiological magnitude (100 mV/mm). Although the expression of β4 integrin had no effect on the rate of cell movement, it was essential for directional (cathodal) migration in the absence of epidermal growth factor (EGF). The addition of EGF potentiated the directional response, suggesting that at least two distinct but synergistic signaling pathways coordinate galvanotaxis. Expression of either a ligand binding–defective β4 (β4+AD) or β4 with a truncated cytoplasmic tail (β4+CT) resulted in loss of directionality in the absence of EGF, whereas inhibition of Rac1 blinded the cells to the EF even in the presence of EGF. In summary, both the β4 integrin ligand–binding and cytoplasmic domains together with EGF were required for the synergistic activation of a Rac-dependent signaling pathway that was essential for keratinocyte directional migration in response to a galvanotactic stimulus.
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Collazo, A., M. Bronner-Fraser, and S. E. Fraser. "Vital dye labelling of Xenopus laevis trunk neural crest reveals multipotency and novel pathways of migration." Development 118, no. 2 (1993): 363–76. http://dx.doi.org/10.1242/dev.118.2.363.
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Although the Xenopus embryo has served as an important model system for both molecular and cellular studies of vertebrate development, comparatively little is known about its neural crest. Here, we take advantage of the ease of manipulation and relative transparency of Xenopus laevis embryos to follow neural crest cell migration and differentiation in living embryos. We use two techniques to study the lineage and migratory patterns of frog neural crest cells: (1) injections of DiI or lysinated rhodamine dextran (LRD) into small populations of neural crest cells to follow movement and (2) injections of LRD into single cells to follow cell lineage. By using non-invasive approaches that allow observations in living embryos and control of the time and position of labelling, we have been able to expand upon the results of previous grafting experiments. Migration and differentiation of the labelled cells were observed over time in individual living embryos, and later in sections to determine precise position and morphology. Derivatives populated by the neural crest are the fins, pigment stripes, spinal ganglia, adrenal medulla, pronephric duct, enteric nuclei and the posterior portion of the dorsal aorta. In the rostral to mid-trunk levels, most neural crest cells migrate along two paths: a dorsal pathway into the fin, followed by presumptive fin cells, and a ventral pathway along the neural tube and notochord, followed by presumptive pigment, sensory ganglion, sympathetic ganglion and adrenal medullary cells. In the caudal trunk, two additional paths were noted. One group of cells moves circumferentially within the fin, in an arc from dorsal to ventral; another progresses ventrally to the anus and subsequently populates the ventral fin. By labelling individual precursor cells, we find that neural tube and neural crest cells often share a common precursor. The majority of clones contain labelled progeny cells in the dorsal fin. The remainder have progeny in multiple derivatives including spinal ganglion cells, pigment cells, enteric cells, fin cells and/or neural tube cells in all combinations, suggesting that many premigratory Xenopus neural crest precursors are multipotent.
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Lohmann, Kenneth J., and Catherine M. F. Lohmann. "Sea Turtle Navigation and the Detection of Geomagnetic Field Features." Journal of Navigation 51, no. 1 (1998): 10–22. http://dx.doi.org/10.1017/s0373463397007649.
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The lives of sea turtles consist of a continuous series of migrations. As hatchlings, the turtles swim from their natal beaches into the open sea, often taking refuge in circular current systems (gyres) that serve as moving, open-ocean nursery grounds. The juveniles of many populations subsequently take up residence in coastal feeding areas that are located hundreds or thousands of kilometres from the beaches on which the turtles hatched; some juveniles also migrate between summer and winter habitats. As adults, turtles periodically leave their feeding grounds and migrate to breeding and nesting regions, after which many return to their own specific feeding sites. The itinerant lifestyle characteristic of most sea turtle species is thus inextricably linked to an ability to orient and navigate accurately across large expanses of seemingly featureless ocean.In some sea turtle populations, migratory performance reaches extremes. The total distances certain green turtles (Chelonia mydas) and loggerheads (Caretta caretta) traverse over the span of their lifetimes exceed tens of thousands of kilometres, several times the diameter of the turtle's home ocean basin. Adult migrations between feeding and nesting habitats can require continuous swimming for periods of several weeks. In addition, the paths of migrating turtles often lead almost straight across the open ocean and directly to the destination, leaving little doubt that turtles can navigate to distant target sites with remarkable efficiency.