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PubMedDate not supplied

Genetic structure of an Apis dorsata population: the significance of migration and colony aggregation.

Eight microsatellite loci were used to investigate the genetic structure of the giant honeybee (Apis dorsata) population in northeast India. This species migrates seasonally between summer and winter nesting sites, and queens appear to return to their previously occupied site. Furthermore, there is a strong tendency for colonies of this species to aggregate at perennially utilized nesting sites that may be shared by more than 150 colonies. These behavioral features suggest that colonies within aggregations should be more related than random colonies, but that the long-distance migration could act to minimize genetic differentiation both between geographical areas and within aggregations. Our genetic study supports these conjectures arising from natural history. A. dorsata aggregations are comprised of colonies that share more alleles than expected by chance. Although queens heading neighboring colonies are not close relatives, fixation indices show significant genetic differentiation among aggregation sites. However, there appears to be sufficient gene flow among aggregations to prevent high degrees of relatedness developing between colonies within aggregations. The results also suggest that there is significant population structuring between geographical regions, although the level of structuring caused by aggregation exceeds the differentiation attributable to geographic region.

Animal Migration↗
PubMed2006

Fracture and migration of a suprarenal inferior vena cava filter in a pregnant patient.

Placement of retrievable inferior vena cava (IVC) filters as prophylaxis for pulmonary embolism (PE) is an increasingly attractive option for patients who require temporary IVC filtration. However, experience thus far with retrievable filters in pregnant patients is limited. This report describes a suprarenally placed Recovery IVC filter in a pregnant woman with PE despite therapeutic anticoagulation. After failed induction of labor and uneventful cesarean section, the patient returned for filter retrieval 167 days after initial placement. Fracture and inferior migration of the filter was observed, and subsequent attempts at filter retrieval were unsuccessful.

Adult↗
PubMed2005

Growth cones turn and migrate up an immobilized gradient of the laminin IKVAV peptide.

Growth cone navigation is guided by extrinsic environmental proteins, called guidance cues. Many in vitro studies have characterized growth cone turning up and down gradients of soluble guidance cues. Although previous studies have shown that axonal elongation rates can be regulated by gradients of surface-bound molecules, there are no convincing demonstrations of growth cones turning to migrate up a surface-bound gradient of an adhesive ligand or guidance cue. In order to test this mode of axonal guidance, we used a photo-immobilization technique to create grids and gradients of an adhesive laminin peptide on polystyrene culture dish surfaces. Chick embryo dorsal root ganglia (DRGs) were placed on peptide grid patterns containing surface-bound gradients of the IKVAV-containing peptide. DRG growth cones followed a path of surface-bound peptide to the middle of a perpendicularly oriented gradient with a 25% concentration difference across 30 microm. The majority of growth cones turned and migrated up the gradient, turning until they were oriented directly up the gradient. Growth cones slowed their migration when they encountered the gradient, but growth cone velocity returned to the previous rate after turning up or down the gradient. This resembles in vivo situations where growth cones slow at a choice point before changing the direction of axonal extension. Thus, these results support the hypothesis that mechanisms of axonal guidance include growth cone orientation by gradients of surface-bound adhesive molecules and guidance cues.

Animals↗
PubMed1975

Sorosporium consanguineum: relation between variable nuclear condition and dissociation.

Saprophytic development of Sorosporium consanguineum and its nuclear cycle were studied on laboratory media. During vegetative reproduction, the nuclei of the monokaryotic sporidia were shown to first migrate into developing bud cells where division occurs, one nucleus returning to the parent cell prior to completion of cell division. Following fusion of sporidia of opposite mating type and subsequent formation of infection hyphae, dikaryons eventually dissociated, giving rise to sporidia of both sex groups in the process. As a result of dissociation, shown to occur in several ways, "satellite" sporidial colonies characteristically formed in advance of the parent colony and fusions again occurred between sporidia of opposite mating type. Reports of variable nuclear condition of mycelia in other species of smut fungi in culture are discussed in light of these findings.

Basidiomycota↗
PubMed1977

[Interkinetic nuclear migration in nasal placode of chick embryo].

Cells of nasal placode of chick embryos were studied with thymidine H3 and autoradiography. Our results shown, that the nuclei in the nasal placode synthesize DNA in the outer zone, then migrate toward the inner zone to undergo division and subsequently return to the outer zone.

Animals↗
PubMed1991

IL-1 alpha inhibits lymphocyte migration into a site of chronic inflammation.

The effects of murine recombinant IL-1 alpha (muIL-1 alpha) on lymphocyte migration in the mouse have been investigated. Continuous infusion of muIL-1 alpha had marked effects on patterns of lymphocyte migration into a site of chronic inflammation, inflammatory exudate and spleen; the numbers of lymphocytes migrating to the inflamed tissue and spleen were reduced in a dose-dependent manner. The number of lymphocytes in the blood of muIL-1 alpha-treated animals was increased in a dose-related manner. The decrease in numbers of lymphocytes present in the chronically inflamed site may either be due to a direct inhibitory action of muIL-1 alpha or reflect an increased rate of cell migration through the inflamed tissues accompanied by a more rapid return to the circulation. These findings suggest that IL-1 alpha may act not only as an inflammatory cytokine, but also as a modulator with anti-inflammatory activity during chronic inflammation.

Animals↗
PubMed2006

Anti-allodynic property of flavonoid myricitrin in models of persistent inflammatory and neuropathic pain in mice.

The aim of the present study was to investigate the effects of myricitrin, a flavonoid with anti-inflammatory and antinociceptive action, upon persistent neuropathic and inflammatory pain. The neuropathic pain was caused by a partial ligation (2/3) of the sciatic nerve and the inflammatory pain was induced by an intraplantar (i.pl.) injection of 20 microL of complete Freund's adjuvant (CFA) in adult Swiss mice (25-35 g). Seven days after sciatic nerve constriction and 24 h after CFA i.pl. injection, mouse pain threshold was evaluated through tactile allodynia, using Von Frey Hair (VFH) filaments. Further analyses performed in CFA-injected mice were paw edema measurement, leukocytes infiltration, morphological changes and myeloperoxidase (MPO) enzyme activity. The intraperitoneal (i.p.) treatment with myricitrin (30 mg/kg) significantly decreased the paw withdrawal response in persistent neuropathic and inflammatory pain and decreased mouse paw edema. CFA injection increased 4-fold MPO activity and 27-fold the number of neutrophils in the mouse paw after 24 h. Myricitrin strongly reduced MPO activity, returning to basal levels; however, it did not reduce neutrophils migration. In addition, myricitrin treatment decreased morphological alterations to the epidermis and dermis papilar of mouse paw. Together these results indicate that myricitrin produces pronounced anti-allodynic and anti-edematogenic effects in two models of chronic pain in mice. Considering that few drugs are currently available for the treatment of chronic pain, the present results indicate that myricitrin might be potentially interesting in the development of new clinically relevant drugs for the management of this disorder.

Animals↗
PubMed2003

Evidence for bimodal hybrid zones between two species of char (Pisces: Salvelinus) in northwestern North America.

Dolly Varden (Salvelinus malma, Pisces: Salmonidae) and bull trout (Salvelinus confluentus) have widely overlapping, but largely parapatric ranges in watersheds in northwestern North America from Washington State to northern British Columbia. Genetic analysis of natural populations using diagnostic molecular markers revealed widespread local sympatry and hybridization with hybrids comprising 0-25% of the local samples. In a detailed analysis of hybridization using four nuclear DNA markers and mitochondrial DNA within the Thutade Lake watershed, northcentral British Columbia, hybrid genotypes constituted up to 9% of the population of juvenile char. There were significant deviations from Hardy-Weinberg, gametic, and cytonuclear equilibria, and local samples showed bimodal frequency distributions of genotypes. Pure parental and inferred backcross genotypes were most common, and F1 and F(n) hybrids were comparatively rare. Interspecific hybridization was asymmetrical, with most F1 hybrids (five of six) bearing S. confluentus mtDNA. The introgression of nuclear and mitochondrial alleles was asymmetrical, with S. confluentus mtDNA and Growth Hormone 2 introgressing into S. malma significantly more than either introgression of the three other nuclear loci, or introgression of S. malma alleles into S. confluentus. Substantial prezygotic isolation between the species likely depends on the large body size difference between them in sympatry: S. malma have small bodies and a stream resident life history (12-21 cm adult fork length at maturity), while S. confluentus are larger and adfluvial, i.e., they migrate to Thutade Lake where they grow to maturity before returning to tributary streams to spawn (40-90 cm at maturity). These traits may limit interspecific pairings because of size assortative pairing and size-dependent reproductive habitat use.

Animals↗
PubMed1977

[Changes in the electric charge of blood lymphocyte populations after secondary immunization with tetanus antitoxin in man].

The electrophoretic mobility of circulating lymphocytes has been studied in normal human subjects after immunization by tetanus toxoid. The mean migration speed was shown to increase, particularly two and three days after secondary immunization. This increase appeared to be due to the elevation of percentage of T cells migrating at 1.20 and 1.35 micrometer. sec.-1v.-1 cm. (active rosettes-forming cells), with a decrease of the percentage of B cells and T lymphocytes migrating at 1.10 micrometer. sec.-1v.-1 cm. The return to the anterior status was observed between day 4 and 8 after immunization.

Electrophoresis↗
PubMedDate not supplied

Passenger-women: changing gender relations in the Tari Basin.

Papua New Guinea is in the early stages of an HIV/AIDS epidemic. It is important to understand how the sexual behaviour of Huli men and women will influence the form of the epidemic in the Tari area. High numbers of single and married men migrating out of the Tari area in search of employment, returning with sexually transmitted infections, are one cause for concern. Another is the emergence of a form of prostitution in the Tari area. This paper describes an unusual aspect of female sexual behaviour at Tari in which some women become sexually promiscuous, behaving in a manner that could be labelled prostitution. This behaviour scandalizes their families and results in a debasing of their value as brides. However, the women involved do not see their actions as being part of any form of sex work. Rather, they participate in this behaviour because they are frustrated and angry. The women feel their male kin have not fulfilled customary obligations to them as women; often the women have been raped and their assailants neither apprehended nor punished. As a result the women have come to believe that the meaning and function of bridewealth marriage has changed such that women are like commodities to be bought and sold. They see their behaviour as a form of revenge on their families and on a culture that seemingly no longer values them as persons.

Adolescent↗
PubMed1977

[Interkinetic migration of the auditory placode in the chick embryo].

Interkinetic nuclear migration was studied in cells forming the auditory placode of chick embryos with thymidine H3 and autoradiography. Our results show, that the nuclei in the auditory placode, synthesize D.N.A. in the outer zone, then migrate toward the inner zone to undergo division and subsequently return to the outer zone.

Animals↗
PubMed2001

Swimming speeds and buoyancy compensation of migrating adult chum salmon Oncorhynchus keta revealed by speed/depth/acceleration data logger.

Although the homing migration of Pacific salmon is well documented, the swimming behaviour of the returning salmon has been poorly described, principally as a result of the difficulties encountered in monitoring salmon behaviour in the sea. The present study describes the use of a recently developed electronic data logger to obtain simultaneous recordings of the swimming speed, depth, fin-beating activity and body angle of free-ranging chum salmon Oncorhynchus keta during their homing migration in coastal waters. Chum salmon migrated horizontally at speeds of 1.5-3.0 km h(-1). The gross horizontal distance salmon moved during total recording periods were 1.24- to 19.0-fold greater than the net distance from the release site to the retrieval points. It is suggested that homing salmon did not drift passively but swam actively to the spawning grounds. Salmon preferred the surface water, but also made frequent vertical migrations. The travelled depth of each salmon ranged from 0.36 to 0.64 km per hour. Salmon descended at faster rates and steeper angles than they ascended. Both tailbeat frequency and tail thrust were higher during the ascent than the descent phase. These results suggest that chum salmon spent more energy during the ascent than the descent phase. Profiles of descent rate assumed an arched shape with respect to a change in hydrostatic pressure, while ascent rate increased with decreasing depth. High tailbeat frequencies were found during the course of ascent, which suggests that the salmon did not regulate the volume of air in the swim bladder during short-term vertical migrations.

Animal Migration↗
PubMed1999

Guestworker migration, remittances and the extended family: evidence from Pakistan.

"The paper places migration in the context of the extended family. It models informal loans between migrant and extended family for financing the costs of international labor migration. To show repayments to extended family is important; we trace the effects of such loans on migrant savings and remittance to the immediate family. We employ a standard life-cycle approach, which predicts that the demand for extended family financing rises with migration costs and falls with pre-migration wealth. Remittance to the immediate family and savings retained abroad both fall with the pre-migration loan." These hypotheses are tested using data from a survey of return migrants to Pakistan carried out in 1986.

Asia↗
PubMed1982

Immunity to herpes simplex virus type 2. IV. Impaired lymphokine production during recrudescence correlates with an imbalance in T lymphocyte subsets.

Cell-mediated immunity (CMI) to herpes simplex virus type 2 (HSV-2) was studied in patients with recurrent disease. Peripheral blood lymphocytes (PBL) obtained during recrudescence (0 to 3 days post-onset of lesion), convalescence (4 to 14 days), and quiescence (greater than 14 days), which were cultured in vitro in the presence of UV-inactivated HSV-2 (G) antigen, demonstrated similar, virus-specific lymphoproliferative responses. However, the production of the lymphokine, leukocyte migration-inhibition factor (LIF), was completely suppressed during recrudescence. During convalescence, LIF production returned to levels similar to those of PBL from seropositive controls (without a history of recurrent subsets revealed a significant increase in the proportion of T8+ and Ia+ cells during recrudescence and at prodrome (24 to 48 hr before onset of lesions). Glass adherence reduced the proportion of both T8+ and Ia+ cells and restored early (1 day) LIF activity, and recrudescent PBL suppressed the proliferation of autologous T cells in presence of UV-HSV-2 (G) antigen. The expression of both phenotypes and LIF production returned to control levels during convalescence.

Antibodies, Monoclonal↗
PubMed2001

Metabolic status and respiratory physiology of Gecarcoidea natalis, the Christmas Island red crab, during the annual breeding migration.

With the arrival of the monsoonal rains and after months of inactivity during the dry season, the terrestrial crab Gecarcoidea natalis embarks on its annual breeding migration to the coast. The physiological demands of the migration were assessed by determining respiratory gases in the hemolymph, key metabolites, and energy stores in G. natalis during two migratory seasons. At the end of each day of migration the pulmonary hemolymph PO2 decreased by 1-2.5 kPa, but the hemocyanin remained saturated with O2 and the venous reserve was largely unchanged (O2 > 0.4 mmol x l(-1)). The breeding migration of red crabs was accomplished without recourse to anaerobiosis, even though at times walking speeds (up to 6.2 +/- 0.5 m x min(-1)) exceeded those that promoted anaerobiosis in non-migrating crabs and in crabs exercised in the laboratory. In contrast to all previous studies, at the end of each day of migrating, red crabs experienced an alkalosis (up to 0.1 pH units) rather than any acidosis. This alkalosis was removed overnight when the crabs were inactive. Although there were seasonal fluctuations in the glycogen, glucose, and triglyceride stores, crabs engaging in the migration did not draw on these stores and must have fed along the way. In contrast, crabs returning from breeding activities on the shore terraces had significantly depleted glycogen stores. Additionally, in 1993, the male crabs returning from the breeding activities on the terraces were dehydrated and experienced a decrease in muscle tissue water of 11%. In contrast to the breeding migration per se, fighting for burrows in which breeding occurs produced severe anaerobiosis in males, especially the victors: after 135 s of combat, the maximum L-lactate concentration in the hemolymph was 35 mmol x l(-1). It appears that burrowing, courtship, and mating are more demanding than the migration itself. Furthermore, the data provide evidence that the metabolic responses of migrating individuals of G. natalis might be different from those at other times of the year.

Animals↗
PubMed1999

Differentiated intestinal epithelial cells exhibit increased migration through polyamines and myosin II.

Early mucosal restitution is a rapid process by which differentiated intestinal epithelial cells migrate to reseal superficial wounds. However, most of the in vitro studies for restitution employ undifferentiated intestinal crypt cells as a model. The transcription factor, Cdx2, plays an important role in the regulation of intestinal epithelial differentiation. Forced expression of the Cdx2 gene in undifferentiated intestinal crypt cells induces the development of a differentiated phenotype. The current study was designed to determine changes in differentiated intestinal epithelial cell migration after wounding in the stable Cdx2-transfected IEC-6 cells and then to examine involvement of polyamines and nonmuscle myosin II in the process of cell motility. Cdx2-transfected IEC-6 cells were associated with a highly differentiated phenotype and exhibited increased cell migration after wounding. Migration of Cdx2-transfected IEC-6 cells were approximately four times that of nontransfected IEC-6 cells. Migration after wounding was associated with significant increases in polyamine synthesis. Depletion of cellular polyamines by 5 mM alpha-difluoromethylornithine (DFMO), a specific inhibitor of polyamine biosynthesis, inhibited cell migration without affecting the differentiated phenotype. DFMO also decreased levels of nonmuscle myosin II mRNA and protein and resulted in reorganization of myosin II, along with a marked reduction in stress fibers. Exogenous spermidine given together with DFMO not only returned nonmuscle myosin II levels and cellular distribution toward normal but also restored cell migration to control levels. These results indicate that 1) Cdx2-transfected IEC-6 cells exhibit increased cell migration after wounding and 2) cellular polyamines are absolutely required for stimulation of cell migration in association with their ability to modulate the structural organization of nonmuscle myosin II.

Animals↗
PubMed1995

Profile of HIV disease in an American border city.

A previous study on patterns of migration of HIV-infected persons suggested that most patients in a rural setting in eastern Tennessee acquired their disease in an urban area, typically during a period of prolonged residence. Disease and disability were the most common reasons for returning to their hometown. We studied our urban, border-city HIV clinic population to see whether similar patterns of migration were discernible. Fifty-one of the 103 patients studied lived outside the El Paso/Juarez area when they contracted HIV infection. The major reason cited for returning home was a desire to return to family (25%). Those who returned and those who had never left showed no statistically significant difference in age, race, or risk factors. This study suggests that migration of HIV-infected patients back to their hometown does not appear to be an exclusively rural phenomenon.

Acquired Immunodeficiency Syndrome↗
PubMed1998

[Swedish migration in a current, historical and international perspective: immigration put more demands on health care].

Sweden will soon have a million foreign-born residents, representing almost 11 per cent of the population. As shown in the article, migration to Sweden is a continuing process rather than an isolated life event; for example, half of those who emigrated to Sweden in 1968 had returned to their home country or proceeded to a new country by 1988. The possible effects of the migration process upon immigrants, and the ensuing impact on primary health care, are examined in the article. Published findings suggest that immigrants--whether they migrate because of war, political or religious persecution, or for economic reasons--may experience increased stress, thus exacerbating any individual susceptibility to illness. Strategies for future research in migration medicine and primary health care are also discussed.

Cross-Cultural Comparison↗