906 resultados para reproductive migration
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O objetivo deste estudo é caracterizar pela primeira vez alguns aspectos da reprodução do caranguejo-uçá em manguezais da Baía da Babitonga (Santa Catarina). Além disso, a densidade e o tamanho do estoque deste recurso pesqueiro foram também estimados. Os exemplares foram coletados mensalmente, de maio de 2002 a abril de 2003, em duas áreas distintas: Iperoba e Palmital; um total de 2265 espécimes (1623 machos e 642 fêmeas) foi analisado. Os machos com gônadas maturas foram registrados durante todo o ano, enquanto as fêmeas com gônadas maturas ocorreram em apenas cinco meses. As fêmeas ovígeras foram registradas apenas em dezembro e janeiro. O etograma do fenômeno de migração reprodutiva (andada) esteve em concordância com a maior atividade de caranguejos associada às luas cheias e novas, com maior intensidade em dezembro e janeiro, relacionados ao verão austral. A densidade total no Manguezal de Iperoba foi de 2,05 ± 0,97 ind./m², não diferindo significativamente daquela registrada para o Manguezal do Palmital (2,06 ± 1,08 ind./m²) (p < 0,05). A média global para a estimativa de densidade na Baia da Babitonga foi de 2,05 ± 1,00 ind./m², correspondendo a 1,42 ± 0,89 ind./m² com base nas galerias abertas e 0,64 ± 0,63 ind./m² para as galerias fechadas.
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Estômagos de 222 tubarões-azuis coletados ao longo da costa brasileira foram analisados, sendo 116 da região nordeste e 106 da região sul. Um total de 51 táxons de presas foram identificados. Os itens mais importantes na região sul foram baleias Mysticeti, teleósteos, o peixe gempilídeo Ruvettus pretiosus e o nomeídeo Arioma bondi. Cefalópodes foram mais diversos, com preferência pelas espécies migradoras verticais Histioteuthis spp., Cranchiidae e o polvo epipelágico Ocythoe tuberculata. Na região nordeste, o tubarão-azul consumiu principalmente teleósteos, incluindo o peixe alepisaurídeo Alepisaurus ferox e o gempilídeo Gempylus serpens. Entre os cefalópodes, Histioteuthis spp. e o polvo epipelágico Tremoctopus violaceus foram os itens principais. Predação sobre cardumes foi ocasional, como observada para Arioma bondi. Aves também foram consumidas em ambas as regiões. Puffinus gravis foi o quinto item mais freqüente na região nordeste. Durante o ciclo migratório reprodutivo, o tubarão-azul costuma predar nas adjacências da termoclina, que é mais profunda na região nordeste e mais perto da superfície na região sul.
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A espécie Prochilodus lineatus é de grande importância comercial na região dos rios Grande, Pardo e Mogi-Guaçu e tem como característica a formação de grandes cardumes, apta a desenvolver amplos deslocamentos migratórios. O presente trabalho objetivou avaliar, por meio das características morfométricas e etária, se os curimbatás (P. lineatus) dos diferentes estoques migradores e residentes constituem uma única população, havendo interação entre as sub-populações no período de piracema (migração reprodutiva). Utilizou-se um delineamento inteiramente casualizado em esquema fatorial 4 x 2, com quatro tipos de estoques (um residente e três migradores) e dois sexos (macho e fêmea) com trinta repetições, considerando cada peixe como unidade experimental. Foi observada variação de 80,19% para o primeiro componente principal e 8,09% do segundo componente principal fornecida pelas dez variáveis morfométricas dos estoques residentes e migradores. O estoque residente correspondeu aos maiores valores para todas as variáveis morfométricas. Houve sobreposição dos escores individuais das mesmas características entre os estoques migradores. Observou-se predominância de machos entre os estoques residentes e migrador I e II. As semelhanças morfométricas verificadas entre os estoques migradores indicam tratar-se de uma única população, com pequenas variações interpopulacional.
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Includes bibliography
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Research on the relationship between reproductive work and women´s life trajectories including the experience of labour migration has mainly focused on the case of relatively young mothers who leave behind, or later re-join, their children. While it is true that most women migrate at a younger age, there are a significant number of cases of men and women who move abroad for labour purposes at a more advanced stage, undertaking a late-career migration. This is still an under-estimated and under-researched sub-field that uncovers a varied range of issues, including the global organization of reproductive work and the employment of migrant women as domestic workers late in their lives. By pooling the findings of two qualitative studies, this article focuses on Peruvian and Ukrainian women who seek employment in Spain and Italy when they are well into their forties, or older. A commonality the two groups of women share is that, independently of their level of education and professional experience, more often than not they end up as domestic and care workers. The article initially discusses the reasons for late-career female migration, taking into consideration the structural and personal determinants that have affected Peruvian and Ukrainian women’s careers in their countries of origin and settlement. After this, the focus is set on the characteristics of domestic employment at later life, on the impact on their current lives, including the transnational family organization, and on future labour and retirement prospects. Apart from an evaluation of objective working and living conditions, we discuss women’s personal impressions of being domestic workers in the context of their occupational experiences and family commitments. In this regard, women report varying levels of personal and professional satisfaction, as well as different patterns of continuity-discontinuity in their work and family lives, and of optimism towards the future. Divergences could be, to some extent, explained by the effect of migrants´ transnational social practices and policies of states.
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Background: Macrophage migration inhibitory factor (MIF) has special pro-inflammatory roles, affecting the functions of macrophages and lymphocytes and counter-regulating the effects of glucocorticoids on the immune response. The conspicuous expression of MIF during human implantation and early embryonic development also suggests this factor acts in reproductive functions. The overall goal of this study was to evaluate Mif expression by trophoblast and embryo placental cells during mouse pregnancy. Methods: Mif was immunolocalized at implantation sites on gestation days (gd) 7.5, 10.5, 13.5 and 17.5. Ectoplacental cones and fetal placentas dissected from the maternal tissues were used for Western blotting and qRT-PCR assays on the same gestation days. Results: During the post-implantation period (gd7.5), trophoblast giant cells showed strong Mif reactivity. In later placentation phases (gds 10.5-17.5), Mif appeared to be concentrated in the junctional zone and trophoblast giant cells. Mif protein expression increased significantly from gd7.5 to 10.5 (p = 0.005) and from gd7.5 to 13.5 (p = 0.03), remaining at high concentration as gestation proceeded. Higher mRNA expression was found on gd10.5 and was significantly different from gd13.5 (p = 0.048) and 17.5 (p = 0.009). Conclusions: The up-regulation of Mif on gd10.5 coincides with the stage in which the placenta assumes its three-layered organization (giant cells, spongiotrophoblast and labyrinth zones), fetal blood circulation begins and population of uNK cells reaches high proportions at the maternal counter part of the placenta, suggesting that Mif may play a role in either the placentation or in the adaptation of the differentiated placenta to the uterus or still in gestational immunomodulatory responses. Moreover, it reinforces the possibility of specific activities for Mif at the maternal fetal interface.
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Hippolyte obliquimanus is a small, gonochoric shrimp found in algal substrates along the western Atlantic coast of Brazil, particularly in association with seaweed of the genus Sargassum. We studied population features (sexual ratio, reproductive period and temporal distribution) of H. obliquimanus in southeastern Brazil, including its relationships with the seasonality of banks of this alga. Specimens were collected at two-monthly intervals from March 2005 to January 2006, in Ubatuba Bay. The sex of individuals was checked, and the carapace length measured. In total, 668 individuals were collected: 211 males (0.70-2.50 mm carapace length), 341 non-ovigerous females (0.55-2.90 mm), and 116 ovigerous females (1.55-3.20 mm). Hippolyte obliquimanus showed seasonal-continuous reproduction and variable continuous recruitment. The highest number of animals (75%) was collected in fall-winter. The percentages of ovigerous females/total females (fall-winter: 27%; spring-summer: 26%) and the sexual ratio (fall-winter: 31%; spring-summer: 32%) were practically equal in both periods. The sexual ratio showed a predominance of females in almost all size classes, and we detected a new sex ratio pattern for this species. The seasonal variation in the number of individuals can be related to its migration to deeper areas, due to the decrease in the abundance of Sargassum sp. in shallower waters in spring-summer.
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We found an increased expression of the TAGLN gene in endometriotic lesions compared with the eutopic endometrium of the same patients by real-time polymerase chain reaction. It is possible that this deregulation contributes to the development and maintenance of endometriosis by being involved in the pathways of organization of cytoskeletal architecture. (Fertil Steril (R) 2011;96:700-3. (C)2011 by American Society for Reproductive Medicine.)
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We collected data on plasma levels of testosterone+5a-dihydrotestosterone (T+DHT) and corticosterone (CORT) from adult female green sea turtles (Chelonia mydas) from southern Queensland during distinct stages of their reproductive cycle. Those females capable of breeding in a given year had elevated plasma steroid levels (T+DHT 0.91 +/- 0.08; CORT 1.05 +/- 0.29 ng/ml), associated with follicular development, until courtship began in October. At the beginning of the nesting season in November plasma levels of 2 CORT were related to when the female first nested (r(2) = 0.06; F = 10.45; P = 0.01). However, they were not correlated with the number of clutches a female laid in that season (F = 3.65; P = 0.08). We repeatedly sampled 23 turtles over the nesting season and profiled changes in steroids immediately following oviposition of each clutch. Levels of T+DHT (range 0.41-0.58 ng/ml) and CORT (range 2.13-2.81 ng/ml) were similar through the early stages of the nesting season and inter-nesting period, and declined to near basal levels (T+DHT 0.37 +/- 0.03 and CORT 1.85 +/- ng/ml) following the last clutch for the season. Steroid hormone levels were also low (T+DHT 0.38 +/- 0.16; CORT 0.46 +/- 0.21 ng/ml) in four independent post-breeding (atretic) females; samples for these females were taken at a time when body condition was presumably at the lowest for the season. Subtle changes in the nesting environment, such as variation in nesting habitat or the time of night that nesting occurred, were associated with a small and slow CORT increase. We suggest CORT is increased in nesting females to assist in lipid transfer to prepare the ovarian follicles and/or the reproductive organs for ovulation.
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Bisphenol A (BPA) is an endocrine disrupting chemical (EDC) whose migration from food packaging is recognized worldwide. However, the real overall food contamination and related consequences are yet largely unknown. Among humans, children’s exposure to BPA has been emphasized because of the immaturity of their biological systems. The main aim of this study was to assess the reproductive impact of BPA leached from commercially available plastic containers used or related to child nutrition, performing ecotoxicological tests using the biomonitoring species Daphnia magna. Acute and chronic tests, as well as single and multigenerational tests were done. Migration of BPA from several baby bottles and other plastic containers evaluated by GC-MS indicated that a broader range of foodstuff may be contaminated when packed in plastics. Ecotoxicological test results performed using defined concentrations of BPA were in agreement with literature, although a precocious maturity of daphnids was detected at 3.0 mg/L. Curiously, an increased reproductive output (neonates per female) was observed when daphnids were bred in the polycarbonate (PC) containers (145.1±4.3 % to 264.7±3.8 %), both in single as in multigenerational tests, in comparison with the negative control group (100.3±1.6 %). A strong correlated dose-dependent ecotoxicological effect was observed, providing evidence that BPA leached from plastic food packaging materials act as functional estrogen in vivo at very low concentrations. In contrast, neonate production by daphnids cultured in polypropylene and non-PC bottles was slightly but not significantly enhanced (92.5±2.0 % to 118.8±1.8 %). Multigenerational tests also revealed magnification of the adverse effects, not only on fecundity but also on mortality, which represents a worrying trend for organisms that are chronically exposed to xenoestrogens for many generations. Two plausible explanations for the observed results could be given: a non-monotonic dose–response relationship or a mixture toxicity effect.
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Parasites of the genus Schistosoma were among the first metazoans to develop separate sexes, which is chromosomally determined in the fertilized egg. Despite the occurrence of specific sex chromosomes, the females of most Schistosomatidae species do not complete their somatic development and reach no sexual maturity without the presence of males. Indeed, the most controversial and at the same time most fascinating aspect about the sexual development of Schistosoma females lies on discover the nature of the stimulus produced by males that triggers and controls this process. Although the nature of the stimulus (physical or chemical) is a source of controversy, there is agreement that mating is a necessary requirement for maturation to occur and for migration of the female to a definitive final site of residence in the vascular system of the vertebrate host. It has also been proposed that the stimulus is not species-specific and, in some cases, not even genus-specific. Despite a vast literature on the subject, the process or processes underlying the meeting of males and females in the circulatory system have not been determined and as yet no consensus exists about the nature of the stimulus that triggers and maintains female development. In the studies about their role, Schistosoma males have been considered, at times pejoratively, the brother, the muscles or even the liver of females. Indeed, it still remains to be determined whether the stimulus responsible for female maturation involves the transfer of hormones, nutrients, neuromediators, mere tactile stimulation or a combination of chemotactic and thigmotactic factors
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ABSTRACT Based on the hypothesis that diel vertical migration (DVM) is a mechanism of predator avoidance, the objective of the present study was to test for the occurrence of DVM in planktivorous fish larvae of Hypophthalmus edentatus (Spix, 1829) (Siluriformes, Pimelodidae) and Plagioscion squamosissimus (Heckel, 1840) (Perciformes, Sciaenidae), and zooplankton (rotifers, cladocerans and copepods) in an isolated tropical lagoon in the floodplain of the Upper Paraná River, Brazil (region of Parque Nacional de Ilha Grande). We investigated spatial overlap between predators (planktivorous fish larvae) and prey (zooplankton), and tested which physical and chemical variables of the water are related to the DVM of the studied communities. We performed nocturnal (8:00 pm and 4:00 am) and diurnal sampling (8:00 am and 4:00 pm) in the limnetic region of the lagoon for six consecutive months, from October 2010 to March 2011, which comprises the reproductive period of the fish species analyzed. During the day the larvae tried to remain aggregated in the bottom of the lagoon, whereas at night they tried to disperse in the water column. Especially for cladocerans, the diel vertical migration is an important behavior to avoid predation larvae of H. edentatus and P. squamosissimus once decreased spatial overlap between secured and its potential predators, which corroborates the hypothesis that DVM is a mechanism of predator avoidance. Although significant correlations were observed between the abiotic factors and WMD of microcrustaceans at certain times of day, the effect of predation of fish larvae on zooplankton showed more important in this environment, because the small depth and isolation not allow great variation of abiotic factors seasonally and between strata the lagoon.
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Habitat restoration measures may result in artificially high breeding density, for instance when nest-boxes saturate the environment, which can negatively impact species' demography. Potential risks include changes in mating and reproductive behaviour such as increased extra-pair paternity, conspecific brood parasitism, and polygyny. Under particular cicumstances, these mechanisms may disrupt reproduction, with populations dragged into an extinction vortex. With the use of nuclear microsatellite markers, we investigated the occurrence of these potentially negative effects in a recovered population of a rare secondary cavity-nesting farmland bird of Central Europe, the hoopoe (Upupa epops). High intensity farming in the study area has resulted in a total eradication of cavity trees, depriving hoopoes from breeding sites. An intensive nest-box campaign rectified this problem, resulting in a spectacular population recovery within a few years only. There was some concern, however, that the new, high artificially-induced breeding density might alter hoopoe mating and reproductive behaviour. As the species underwent a serious demographic bottleneck in the 1970-1990s, we also used the microsatellite markers to reconstitute the demo-genetic history of the population, looking in particular for signs of genetic erosion. We found i) a low occurrence of extra-pair paternity, polygyny and conspecific brood parasitism, ii) a high level of neutral genetic diversity (mean number of alleles and expected heterozygosity per locus: 13.8 and 83%, respectively) and, iii) evidence for genetic connectivity through recent immigration of individuals from well differentiated populations. The recent increase in breeding density did thus not induce so far any noticeable detrimental changes in mating and reproductive behaviour. The demographic bottleneck undergone by the population in the 1970s-1990s was furthermore not accompanied by any significant drop in neutral genetic diversity. Finally, genetic data converged with a concomitant demographic study to evidence that immigration strongly contributed to local population recovery.
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Nombre de femmes paysannes haïtiennes migrent vers Port-au-Prince où elles deviennent travailleuses domestiques. Leur service domestique permet aux femmes qui les emploient de s'investir dans le travail non-domestique et de pouvoir accéder ainsi à la migration internationale. En France, ces migrantes deviennent à leur tour travailleuses domestiques, ce qui permet aux femmes françaises de s'investir dans le travail non-domestique. Ces phénomènes témoignent de l'existence d'une chaîne de travail et de migration où s'articulent les rapports sociaux de sexe, de classe, de race et les confrontations Nord/Sud, au coeur de la mondialisation néolibérale. Quelques-unes de ces femmes racontent leur histoire qui exprime à la fois la violence des rapports sociaux et leurs stratégies pour devenir sujet. Pour penser ces « Sujettes », je propose une approche qui croise la recherche féministe et la sociologie clinique sur les plans théorique, méthodologique et épistémologique. -- Many rural Haitian women migrate to Port-au-Prince and become domestic workers. Their domestic service allows other women to invest in the non-domestic work and access to international migration as well. In France, these Haitian migrants become domestic workers in turn, which allows French women to invest in the non-domestic work. These phenomena demonstrate the existence of a global work and migration chain where gender, class, race and the North/South confrontations are articulated, in the neoliberal globalization. Some of these women tell their life story which expresses both the violence of social problems and their strategies to become subject. To think these "subjects" I propose to cross feminist research and clinical sociology on the theoretical, methodological and epistemological point of view. Intersectionality among gender, race and class, North / South confrontations, productive and reproductive labour , domestic work, domestic service, care work , internal and international migration, neoliberal globalization, clinical sociology.
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Available information on abundance of myctophids and their utilisation indicate that there is excellent scope for development of myctophid fisheries in Indian Ocean. Most of the conventional fish stocks have reached a state of full exploitation or over-exploitation. Hence there is need to locate new and conventional fishery resources in order to fill in the supply-demand gap, in the face of increasing demand for fish. Information on length-weight relationship, age and growth, spawning season, fecundity and age at maturity and information on bycatch discards are required for sustainable utilization of myctophid resource in the Indian Ocean