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PubMed1996

[From Ivory Coast to Italy. Burkina Faso migration patterns and national interests].

"Ivory Coast represents nowadays the first immigration country of West Africa.... The movement of Burkinabe migrants [from Burkina Faso], Bissa in particular, from Ivory Coast to Italy does not improve the fundamental instability.... Italian restrictive immigration policy, at the beginning of the 1990s, in accordance with [the] Schengen agreement, has progressively prevented Burkinabe immigrants from obtaining a regular status, which would assure them of basic rights.... New Italian laws, like the French immigration policy of the mid 1970s, are in fact discouraging return migration and fostering stable migration with the relevant integration policy for those, a small number indeed, who are granted a residence permit." (SUMMARY IN ENG)

Acculturation↗
PubMed1993

Migration patterns of thymus-derived gamma delta T cells during chicken development.

Cell transfer experiments in congenic chick strains, one of which expresses the ov antigen marker, indicate that intestinal gamma delta T cells are derived from gamma delta+ thymocytes in embryos and newly hatched birds, and this early intestinal colonization occurs in two discrete waves. Here, we extend these studies to show that splenic colonization by gamma delta T cells occurs in essentially the same way. Following the engraftment of ov+ thymic lobes in thymectomized ov- recipients, gamma delta T cells migrate both to the spleen and intestine. By 1 week after hatching, a third generation of thymus-derived gamma delta T cells begins to migrate to both peripheral lymphoid organs, and this thymus-dependent seeding process is sustained over the first weeks of life. The survival time for splenic gamma delta migrants is significantly less than for the intestinal migrants. Tissue section analysis indicates that gamma delta T cells enter the intestinal epithelium at all villus levels. A shift in the gamma delta intraepithelial lymphocyte distribution toward the villus tip in thymectomized birds suggests the comigration of enterocytes and gamma delta intraepithelial lymphocytes. However, survival kinetics of the donor gamma delta population and a relatively high division rate of intestinal gamma delta T cells indicate that founder thymic migrants produce relatively long-lived clones of intestinal gamma delta T cells.

Animals↗
PubMed2002

Metal contaminants for modelling lobster (Homarus americanus) migration patterns in the Inner Bay of Fundy, Atlantic Canada.

A method, which uses metal compositions in lobster digestive glands as natural environmental tags, has been developed to trace lobster movements. Lobsters were collected from three selected sites, Minas Channel, Minas Basin, and Cobequid Bay, Inner Bay of Fundy, New Brunswick, Canada, that were known to be contaminated with Cu. Five metal variables (Ag, Cd, Cu, Mn and Zn) were processed for principal component analysis (PCA). Metal concentration and burden models were investigated and PCA was able to differentiate lobsters from the respective catch sites. The method was applied to investigate the May and June lobsters collected at the three sites to determine the migration rate during this period of the fishing season. The results show a high level of mixing at Minas Basin and Cobequid Bay in June, and lobster movement inward toward the inner reaches of the bay, with very limited movement outward from the inner bay.

Animals↗
PubMed1995

Different migration patterns of antigen-presenting cells correlate with Th1/Th2-type responses in mice.

Antibodies are produced when antigen-presenting cells (APC) pulsed with an antigen are injected intravenously (i.v.) into BALB/c mice, but subcutaneous (s.c.) injection of such APC causes delayed-type hypersensitivity (DTH). To identify the anatomic sites where T and B cells are activated, we labelled splenic dendritic cells (DC) with a fluorochrome, PKH 26, injected them i.v. or s.c., and used the label to locate them. When the DC were injected i.v., germinal centres in the spleen were hyperplastic on day 1. Most DC moved to T-dependent areas of the white and red pulp on day 1 and remained there at least until day 5, but no DC migrated into the lymph nodes. When the DC were injected s.c., they were in the sinus on day 1 and had entered T-dependent area of draining lymph nodes only by day 3; hyperplasia of germinal centres in the spleen and migration of DC into the spleen were not found. We used the polymerase chain reaction (PCR) to study which mice had spleen cells and lymph node cells that produced the cytokines interleukin (IL)-2, IL-4, IL-10, and interferon-gamma (IFN-gamma). In the sensitization phase, day 1 after DC injection i.v., almost all IL-10 transcript was found in spleen cells, but after DC injection s.c., IL-2 message was most abundant in lymph node cells. The expression of mRNA for IL-4 and IFN-gamma in mice that received DC i.v. was not different from that in mice that received DC s.c. in this phase. Immunohistochemical staining showed that cells stained for IL-10 were in the T-dependent area of the spleen from mice that received DC i.v. 1 day after the injection. Three days after the injection of DC i.v., cells stained for IL-10 were in the germinal centres as well. The number of such cells in the spleen of mice that received DC i.v. was significantly more than that in mice that received DC s.c. IL-10 may be important in development of TH2 response.

Animals↗
PubMed1984

Migration patterns and functional activity of cloned cytotoxic T lymphocytes in syngeneic and allogeneic mice.

The quantitative distribution of cytolytic T lymphocytes (CTL) generated in mixed leukocyte culture (MLC) and an interleukin-2 (IL-2)-dependent, CTL clone (WRL-A3) was investigated in various tissues of irradiated syngeneic and allogeneic mice. In addition, the ability of the WRL-A3 CTL clone to remain viable and retain antigen specificity following in vivo passage was evaluated. Injection i.v. of 51Cr-labeled cultured CTL resulted in: (1) extensive deposition of cells in the lungs with significantly more lymphocytes being recovered in allogeneic as compared with syngeneic lung tissue; (2) minimal accumulation in spleen with more in syngeneic than in allogeneic tissue; and (3) no localization in blood, femurs, thymus, or lymph nodes. The migration rate of cultured CTL exiting the lung during the first 4 hr was markedly faster in syngeneic than in allogeneic recipients and was directly associated with the distribution of these cells in other tissues at 24 hr. The WRL-A3 CTL clone recovered from irradiated syngeneic and allogeneic lung tissue at 1, 3, 6, 8, and 13 days after i.v. injection remained viable, even though no exogenous IL-2 was administered to the recipient mice. The recovered cells proliferated when recultured with IL-2, and retained their antigen specificity for Qed-1b target cells after in vivo passage. These findings indicate that restricted and undesirable tissue distribution, rather than impaired viability or loss of antigenic specificity, is the major obstacle to successful use of cultured CTL for adoptive immunotherapy of disseminated cancer.

Animals↗
PubMed1996

Migration patterns in pulsed-field electrophoresis of DNA restriction fragments from log-phase mammalian cells after irradiation and incubation for repair.

An assay system was developed to detect changes of restriction fragment profiles obtained after pulsed-field gel electrophoresis (PFGE) for DNA from mammalian cells that were irradiated and incubated for repair. DNA was prepared from irradiated log-phase human melanoma cells (MRI 221) after incubation for repair (6 h) and was digested with the rare-cutting restriction enzyme NotI (RE) prior to PFGE separation. DNA-fragment size distributions were compared to the respective PFGE profiles from unirradiated controls. After doses of 5 and 10 Gy (plus a 6-h incubation for repair), the relative amount of DNA retained in the plug during PFGE was increased. For higher doses (30 and 60 Gy), this phenomenon was superimposed by the residual fragmentation (25-30% of the initial breakage of 0.42 dsb/100 Mbp/Gy). Since irradiated cells accumulated in S phase during incubation for repair, a correction for the reduced electrophoretic migration of DNA from S-phase cells was necessary, and a 0.5% increase in DNA retention per 1% S-phase increment was found. However, the % retention for the 5 Gy plus repair sample was significantly higher than for the S-phase adjusted control (p < 0.01). Radiation induced DNA-protein crosslinks cannot account for the observed phenomenon because of the extensive proteolysis in DNA preparation, and also a loss of restriction enzyme recognition sites appear to be an unlikely explanation from simple quantitative considerations. Based on the recent observation of misrejoining during dsb repair, it is proposed that the incorrect joining of DNA ends also causes a more random distribution of replicating DNA in restriction fragments derived from cells in S phase after incubation for repair. This process would necessarily increase the proportion of DNA unable to migrate in PFGE.

DNA Repair↗
PubMed1993

Migration patterns of lymphocytes following syngeneic heterotopic small bowel transplantation in rodents.

Adult rats received syngeneic accessory small bowel grafts with venous drainage to either the portal vein (hetero-portal) or the inferior vena cava (hetero-systemic). Lymphoid cell recovery in different lymphoid organs (spleen, pooled peripheral lymph nodes, mesenteric nodes, Peyer's Patches) was evaluated at varying times (days 0-300) post-grafting. While minimal changes were observed for cell recovery in other organ tissues, lymphocyte recovery in Peyer's Patches of both host and graft small intestine of hetero-systemic animals was decreased from 10- to 100-fold with respect to hetero-portal recipients or non-operated controls. These changes were seen throughout the time course of the study. In additional experiments, lymphoid cells from different organs/donors were labelled in vitro with 111In and injected intravenously into normal/transplanted recipients. Recovery of 111In in various organs was assessed at 1 and 6 h postinjection. The major change seen was in the decreased ability of mononuclear cells derived from Peyer's Patches to migrate to small intestinal tissue (host and graft) in hetero-systemic recipients. In addition, Peyer's Patch cells from these animals 'homed' poorly to small intestine in non-operated animals by comparison with cells from normal rats (or hetero-portal donors).

Animals↗
PubMed2002

Epithelia-mesenchyme interaction plays an essential role in transdifferentiation of retinal pigment epithelium of silver mutant quail: localization of FGF and related molecules and aberrant migration pattern of neural crest cells during eye rudiment formation.

Homozygotes of the quail silver mutation, which have plumage color changes, also display a unique phenotype in the eye: during early embryonic development, the retinal pigment epithelium (RPE) spontaneously transdifferentiates into neural retinal tissue. Mitf is considered to be the responsible gene and to function similarly to the mouse microphthalmia mutation, and tissue interaction between RPE and surrounding mesenchymal tissue in organ culture has been shown to be essential for the initiation of the transdifferentiation process in which fibroblast growth factor (FGF) signaling is involved. The immunohistochemical results of the present study show that laminin and heparan sulfate proteoglycan, both acting as cofactors for FGF binding, are localized in the area of transdifferentiation of silver embryos much more abundantly than in wild-type embryos. More intense immunohistochemical staining with FGF-1 antibody, but not with FGF-2 antibody, is also found in the neural retina, RPE, and choroidal tissue of silver embryos than in wild-type embryos. HNK-1 immunohistochemistry revealed that clusters of HNK-1-positive cells (presumptive migrating neural crest cells) are frequently located around the developing eyes and in the posterior region of the silver embryonic eye. Finally, chick-quail chimerical eyes were made by grafting silver quail optic vesicles to chicken host embryos: in most cases, no transdifferentiation occurs in the silver RPE, but in a few cases, transdifferentiation occurs where silver quail cells predominate in the choroid tissue. These observations together with our previous in vitro study indicate that the silver mutation affects not only RPE cells but also cephalic neural crest cells, which migrate to the eye rudiment, and that these crest cells play an essential role in the transdifferentiation of RPE, possibly by modifying the FGF signaling pathway. The precise molecular mechanism involved in RPE-neural crest cell interaction is still unknown, and the quail silver mutation is considered to be a good experimental model for studying the role of neural crest cells in vertebrate eye development.

Animals↗
PubMed1995

Schistosoma japonicum and S. mansoni: comparison of larval migration patterns in mice.

Mice were infected percutaneously with cercariae of Schistosoma japonicum or S. mansoni and parasites recovered by tissue-mincing from the skin or lungs or by perfusion of the mesenteric veins. S. japonicum had a narrow peak of recovery (up to 30%) from the lungs 3 days after infection, whereas lung recovery of S. mansoni peaked only on day 6 and levelled off during the following week. Infection with S. japonicum induced lung petechiae, but only after most of the parasites had left the lungs. The axillary lymph nodes draining the infection site increased in weight after infection and this effect was much greater and longer with S. mansoni than with S. japonicum. S. japonicum was perfusable from the mesenteric veins earlier (from day 3 onwards) and in higher number (40-60% from days 6 to 10) than S. mansoni (20% on day 20). The percentage of cercariae developing to adult worms was 57% for S. japonicum and 33% for S. mansoni. The data demonstrate that S. japonicum might escape from local tissue reactions in the skin and lungs and, due to its rapid migration, might induce only poor lymphocyte proliferation. As a possible consequence, S. japonicum may establish more efficiently in mice than S. mansoni.

Animals↗
PubMedDate not supplied

[Recent changes in migration patterns in the Mexico City metropolitan zone].

"This study analyzes the magnitude, evolution over time, and place of origin of migrants to the ZMCM [Mexico City metropolitan zone] during the 1970s and 80s. More specifically, the study attempts to test the following hypothesis: attraction of migrants to the ZMCM has diminished over time;...thus the ZMCM is emerging as an important origin of migrants toward other cities. The article also provides an analysis of the changes in the characteristics of the migrants...." (SUMMARY IN ENG)

Americas↗
PubMed2004

Stocking impact and migration pattern in an anadromous brown trout (Salmo trutta) complex: where have all the stocked spawning sea trout gone?

We examined polymorphism at seven microsatellite loci among sea trout (Salmo trutta) (n = 846) collected from three areas in the Limfjord (Denmark). We then assessed their potential population source by comparing, using a mixed stock analysis (MSA) Bayesian framework, their genetic composition to that of brown trout collected from 32 tributaries pooled into nine geographical regions (n = 3801) and two hatcheries (n = 222) used for stocking. For each of the three regional sea trout groups (western, central and eastern Limfjord, n = 91, n = 426, n = 329, respectively), MSA was conducted with (i) all individuals in the group, (ii) with the subset of spawning sea trout only and (iii) with the subset of foraging, nonspawning individuals only, a subset that consisted primarily of sea trout caught during their first year at sea. For all three regional sea trout groups, a higher proportion of individuals (regardless of whether they were foraging or spawning) appear to have originated from the rivers that drain locally, than from the rivers that drain in other parts of the Limfjord. This suggests (1) that sea trout, at least during their first year at sea, undertake limited migrations within the Limfjord system and (2) that sea trout on their spawning run were caught close to their natal rivers. The proportion of sea trout of hatchery origin varied widely among all three Limfjord areas and broadly reflected regional stocking histories, with high proportions of sea trout of domestic origin in the east (39.3%), where stocking with domestic trout was practised intensely at the time of sampling, and in the west (57.2%), where a programme of coastal stocking of post smolts took place over several years in the early 1990s. In contrast, in the central Limfjord, where stocking with domestic trout was largely abandoned in the early 1990s, the proportion of sea trout of domestic origin was only 8.5%. Interestingly, for all three regional sea trout groups, virtually no sea trout of hatchery origin were found among the spawning individuals, which were on average larger than the nonspawning sea trout. These results suggest that stocked domestic brown trout that become anadromous experience high mortality at sea and are therefore largely absent among the larger, spawning individuals. We conclude that sea trout of domestic origin exhibit much reduced ability to reproduce and are unlikely to contribute significantly to the local gene pool largely because of a relatively high mortality at sea before the onset of maturity.

Animal Migration↗
PubMed1990

Aberrant lymphocyte migration patterns in systemic lupus erythematosus (MRL/l, MRL/n) mice are independent of the micro-environment.

Mice with systemic lupus erythematosus (SLE) have unusual patterns of lymphocyte traffic characterised by diminished uptake of intravenously injected autoimmune cells into lymph nodes. This study examines the influence of the lymphocyte micro-environment on this aberrant migratory behaviour. To evaluate lymph node lymphocyte-endothelial interactions which can affect lymphocyte distribution without the in vivo influence of liver and spleen, the in vitro high endothelial venule (HEV) binding assay was used. Lymph node HEV binding of autoimmune MRL-lpr/lpr (MRL/l) and MRL(-)+/+ (MRL/n) lymphocytes was increased when compared with CBA/T6 lymphocytes and contrasted with diminished lymph node uptake noted in vivo. This was independent of the lymph node source (MRL/l, MRL/n, CBA/T6) onto which the lymphocytes were overlaid. To examine the influence of the microenvironment on in vivo traffic, 21Cr-labelled lymph node cells from normal CBA/T6 mice were injected into sex-matched MRL/l, MRL/n and CBA/T6 recipients. The distribution of cells was the same in each recipient strain suggesting that the micro-environment had little influence on the lymphocyte trafficking profiles of autoimmune mice. This study supports the view that aberrant lymphocyte migration in autoimmune mice results from defects intrinsic to the lymphocyte population and not the micro-environment.

Age Factors↗