877 resultados para post-embrionic development


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Plants have extraordinary developmental plasticity as they continuously form organs during post-embryonic development. In addition they may regenerate organs upon in vitro hormonal induction. Advances in the field of plant regeneration show that the first steps of de novo organogenesis through in vitro culture in hormone containing media (via formation of a proliferating mass of cells or callus) require root post-embryonic developmental programs as well as regulators of auxin and cytokinin signaling pathways. We review how hormonal regulation is delivered during lateral root initiation and callus formation. Implications in reprograming, cell fate and pluripotency acquisition are discussed. Finally, we analyze the function of cell cycle regulators and connections with epigenetic regulation. Future work dissecting plant organogenesis driven by both endogenous and exogenous cues (upon hormonal induction) may reveal new paradigms of common regulation.

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This dissertation is an attempt to use the radical political economy approach, which assumes that there is a connection between a state's strategic interests and the interests of dominant multinational corporations (MNCs) located within a state's territory, to explain continuity in the USAID development agenda and lending patterns during the past 30 years of development aid to Haiti. Employing the qualitative method of "process-tracing," my study concludes that the radical political economy approach has an explanatory power when it comes to understanding continuity in the USAID development agenda and lending patterns during the past 30 years of development aid to Haiti. The evidence shows that USAID has implemented in Haiti, from the 1980s through the post-9/11 Washington Consensus period, neoliberal policies that conform to the political economy of US multinational corporations (US MNCs). Contrary to the claim that the USAID-sponsored post-earthquake development paradigm has departed from previous development strategies, the study has shown that USAID has used the occurrence of the January 2010 earthquake tragedy to accelerate in Haiti the implementation of a neoliberal agenda congenial to the business promotion of multinational investors, particularly US multinational corporations. In terms of the way ahead, the study argues for the implementation of a new development approach articulated by a legitimate Haitian state and primarily intended to promote the socioeconomic development of the poorest Haitians.

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O objetivo do presente trabalho foi testar a influência de quatro dietas alimentares sobre o crescimento populacional, desenvolvimento, comprimento total, peso seco e valor nutricional de duas espécies zooplanctônicas, Moina micrura and Diaphanosoma birgei, com os seguintes tratamentos alimentares: somente alga (A), alga + vitaminas (AV), alga + ração (AR) e alga + ração + vitaminas (ARV). O pico de crescimento para as duas espécies estudadas ocorreu mais rápido no tratamento AV. em geral, o tratamento AV para M. micrura mostrou melhores resultados para taxa intrínseca, fecundidade, desenvolvimento embrionário e pós-embrionário. Já a longevidade e número total de desovas apresentaram melhores resultados no tratamento AR (p < 0,05). Para D. birgei, os melhores resultados foram obtidos nos tratamentos contendo ração e vitamina (p < 0,05). A maior porcentagem de proteínas e lipídeos para os dois cladóceros ocorreu nos tratamentos contendo ração, já o carboidrato foi maior no tratamento contendo somente alga (p < 0,05). em geral, as dietas contendo ração e vitamina apresentaram os melhores resultados para o desenvolvimento dos cladóceros, com qualidade de água adequada para cultivo, podendo ser utilizadas em culturas com altas concentrações em laboratório.

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Background: Several plasma membrane transporters have been shown to mediate the cellular influx and/or efflux of iodothyronines, including the sodium-independent organic anion co-transporting polypeptide 1 (OATP1), the sodium taurocholate co-transporting polypeptide (NTCP), the L-type amino acid transporter 1 (LAT1) and 2 (LAT2), and the monocarboxylate transporter 8 (MCT8). The aim of this study was to investigate if the mRNAs of these transporters were expressed and regulated by thyroid hormone (TH) in mouse calvaria-derived osteoblastic MC3T3-E1 cells and in the fetal and postnatal bones of mice. Methods: The mRNA expression of the iodothyronine transporters was investigated with real-time polymerase chain reaction analysis in euthyroid and hypothyroid fetuses and litters of mice and in MC3T3-E1 cells treated with increasing doses of triiodothyronine (T(3); 10(-10) to 10(-6) M) or with 10(-8) M T(3) for 1-9 days. Results: MCT8, LAT1, and LAT2 mRNAs were detected in fetal and postnatal femurs and in MC3T3-E1 cells, while OATP1 and NTCP mRNAs were not. LAT1 and LAT2 mRNAs were not affected by TH status in vivo or in vitro or by the stage of bone development or osteoblast maturation (analyzed by the expression of osteocalcin and alkaline phosphatase, which are key markers of osteoblastic differentiation). In contrast, the femoral mRNA expression of MCT8 decreased significantly during post-natal development, whereas MCT8 mRNA expression increased as MC3T3-E1 cells differentiated. We also showed that MCT8 mRNA was up-regulated in the femur of hypothyroid animals, and that it was down-regulated by treatment with T(3) in MC3T3-E1 cells. Conclusions: This is the first study to demonstrate the mRNA expression of LAT1, LAT2, and MCT8 in the bone tissue of mice and in osteoblast-like cells. In addition, the pattern of MCT8 expression observed in vivo and in vitro suggests that MCT8 may be important to modulate TH effects on osteoblast differentiation and on bone development and metabolism.

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The weaver ants Camponotus textor (Forel) (Hymenoptera: Formicidae) are native to Central and South America, where they use their larvae to build silken nests by sewing tree leaves together. Few Studies have been conducted with this species, and little is known about the morphology of their larvae. Tie present paper estimated the number of larval instars of C. textor and presents a detailed morphological description of each immature stage based on light and electron microscopic observations. The number of larval in stars was estimated as four based oil the frequency distribution of larval head widths. Tic larvae of this species presented some typical characteristics of Camponotus (Mayr) larvae: body shape `pogonomyrmecoid`, ten pairs of spiracles, antennae with three sensilla, conspicuous `chiloscleres` on the labrum, and mature larvae with pronounced labial pseudopalps. Unprecedented characteristics would include: great diversity of body hair types, and `camponotoid` mandibles but with four medial denticles. This information can aid biological and taxonomic studies with these ants, and may be useful for ant systematics.

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In some insects, the finding of oviposition substrate triggers the uptake into oocytes of yolk proteins that are stored in the fat body during post-embryonic development. The main host of the bean weevil Zabrotes subfasciatus (Coleoptera; Chrysomelidae; Bruchinae; Amblycerini), in which larval resources are the sole source for future egg maturation, is Phaseolus vulgaris. Despite not feeding as adults, females of this species are able to lay eggs after encountering host seeds but it is not known how females react to changes in the availability of bean seeds. In the present study, the behaviour of Z. subfasciatus facing two very different environments for oviposition is investigated, as well as how this influences offspring fitness. The results obtained show that females of Z. subfasciatus react to variations in the availability of seeds belonging to the same host species by adjusting egg size and number. Females on low bean seed density lay larger and fewer eggs than those on high bean seed density, demonstrating a trade-off between these reproductive traits. Moreover, females can adjust egg size to changing levels of host availability during the first 4 days of their oviposition period. Although no difference in offspring weight is found, those from small eggs (low competition environment) result in larger adults. No response to selection on these traits after rearing beetles on the same host for 40 generations is observed. This unresponsiveness may indicate that beetle populations behave according to their reaction norm that already allows rapid adaptation to a varying amount of host-seed availability and better exploitation of the environments of this widespread stored-seed pest.

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In this study the main question investigated was the number and size of both binucleate and mononucleate superior cervical ganglion (SCG) neurons and, whether post-natal development would affect these parameters. Twenty left SCGs from 20 male pacas were used. Four different ages were investigated, that is newborn (4 days), young (45 days), adult (2 years), and aged animals (7 years). By using design-based stereo-logical methods, that is the Cavalieri principle and a physical disector combined with serial sectioning, the total volume of ganglion and total number of mononucleate and binucleate neurons were estimated. Furthermore, the mean perikaryal (somal) volume of mononucleate and binucleate neurons was estimated using the vertical nucleator. The main findings of this study were a 154% increase in the SCG volume, a 95% increase in the total number of mononucleate SCG neurons and a 50% increase in the total volume of SCG neurons. In conclusion, apart from neuron number, different adaptive mechanisms may coexist in the autonomic nervous system to guarantee a functional homeostasis during ageing, which is not always associated with neuron losses. Anat Rec, 292:966-975, 2009. (C) 2009 Wiley-Liss, Inc.

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We carried out a comparative morphological study to evaluate the taxonomic value of seed and seedling traits of Entada polystachya and E. simplicata (Leguminosae, Mimosoideae, Mimoseae). Seeds of both species were collected from wild populations in Roraima State, Brazil. Our results show consistent quantitative and qualitative differences between these species regarding their seeds and seedlings. Testa fracture lines, funiculus impression, lens characters, radicle shape and length, and cotyledon lobes length, seedling morphology group, number of pinnae at first node, and hypocotyl length permit a straightforward distinction of E. polystachya from E. simplicata, supporting a recent treatment of the latter taxon as a distinct species, endemic to Roraima State, northern Amazonia, Brazil.

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This paper forms part of a wider project to show the significance of archival material on distinguished economists, in this case Lauchlin Currie (1902-93), who studied and taught at Harvard before entering government service at the US Treasury and Federal Reserve Board as the intellectual leader of Roosevelt’s New Deal, 1934-39, as FDR’s White House economic adviser in peace and war, 1939-45, and as a post-war development economist. It discusses the uses made of the written and oral material available when the author was writing his intellectual biography of Currie (Duke University Press 1990) while Currie was still alive, and the significance of the material that has come to light after Currie’s death.

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Post-embryonic Development of Ophyra aenescens (Wiedemann, 1830) (Diptera: Muscidae), in Different Diets, under Laboratory Conditions - The performance of various diets (bovine meat, fish- sardine, shrimp, dog faeces, and banana) in Ophyra aenescens development was evaluated. The biology was studied in an incubator (BOD) at 27±1oC and 80±10% of RH. The developmental time from larvae to adult, the developmental time and viability of larvae and pupae, the weight of pupae as well as the sex ratio of the emerging adults were also determined. Beef and shrimp were the more efficient diets for rearing O. aenescens.

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ABSTRACT. Chrysomya albiceps (Wiedemann) and Hemilucilia segmentaria (Fabricius) (Diptera, Calliphoridae) used to estimate the postmortem interval in a forensic case in Minas Gerais, Brazil. The corpse of a man was found in a Brazilian highland savanna (cerrado) in the state of Minas Gerais. Fly larvae were collected at the crime scene and arrived at the laboratory three days afterwards. From the eight pre-pupae, seven adults of Chrysomya albiceps (Wiedemann, 1819) emerged and, from the two larvae, two adults of Hemilucilia segmentaria (Fabricius, 1805) were obtained. As necrophagous insects use corpses as a feeding resource, their development rate can be used as a tool to estimate the postmortem interval. The post-embryonary development stage of the immature collected on the body was estimated as the difference between the total development time and the time required for them to become adults in the lab. The estimated age of the maggots from both species and the minimum postmortem interval were four days. This is the first time that H. segmentaria is used to estimate the postmortem interval in a forensic case.

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OBJECTIVE: We investigated whether the INTERMED, a generic instrument for assessing biopsychosocial case complexity and direct care, identifies organ transplant patients at risk of unfavourable post-transplant development by comparing it to the Transplant Evaluation Rating Scale (TERS), the established measure for pretransplant psychosocial evaluation. METHOD: One hundred nineteen kidney, liver, and heart transplant candidates were evaluated using the INTERMED, TERS, SF-36, EuroQol, Montgomery-Åsberg Depression Rating Scale (MADRS), and Hospital Anxiety & Depression Scale (HADS). RESULTS: We found significant relationships between the INTERMED and the TERS scores. The INTERMED highly correlated with the HADS,MADRS, and mental and physical health scores of the SF-36 Health Survey. CONCLUSIONS: The results demonstrate the validity and usefulness of the INTERMED instrument for pretransplant evaluation. Furthermore, our findings demonstrate the different qualities of INTERMED and TERS in clinical practice. The advantages of the psychiatric focus of the TERS and the biopsychosocial perspective of the INTERMED are discussed in the context of current literature on integrated care.

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Early in female mammalian embryonic development, cells randomly inactivate one of the two X chromosomes to achieve overall equal inactivation of parental X-linked alleles. Hcfc1 is a highly conserved X-linked mouse gene that encodes HCF-1 - a transcriptional co-regulator implicated in cell proliferation in tissue culture cells. By generating a Cre-recombinase inducible Hcfc1 knock-out (Hcfc1(lox)) allele in mice, we have probed the role of HCF-1 in actively proliferating embryonic cells and in cell-cycle re-entry of resting differentiated adult cells using a liver regeneration model. HCF-1 function is required for both extraembryonic and embryonic development. In heterozygous Hcfc1(lox/+) female embryos, however, embryonic epiblast-specific Cre-induced Hcfc1 deletion (creating an Hcfc1(epiKO) allele) around E5.5 is well tolerated; it leads to a mixture of HCF-1-positive and -negative epiblast cells owing to random X-chromosome inactivation of the wild-type or Hcfc1(epiKO) mutant allele. At E6.5 and E7.5, both HCF-1-positive and -negative epiblast cells proliferate, but gradually by E8.5, HCF-1-negative cells disappear owing to cell-cycle exit and apoptosis. Although generating a temporary developmental retardation, the loss of HCF-1-negative cells is tolerated, leading to viable heterozygous offspring with 100% skewed inactivation of the X-linked Hcfc1(epiKO) allele. In resting adult liver cells, the requirement for HCF-1 in cell proliferation was more evident as hepatocytes lacking HCF-1 fail to re-enter the cell cycle and thus to proliferate during liver regeneration. The survival of the heterozygous Hcfc1(epiKO/+) female embryos, even with half the cells genetically compromised, illustrates the developmental plasticity of the post-implantation mouse embryo - in this instance, permitting survival of females heterozygous for an X-linked embryonic lethal allele.