1,929 research outputs found

    Differential Expressions of Nodal-Signal Transducers and Global Transcriptional Repression Commit Vegetal Cells in Eleutherodactylus Coqui to Form Nutritional Endoderm

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    The vegetal core cells of a Xenopus laevis embryo commit to mesendoderm via the Nodal-signaling pathway. In Eleutherodactylus coqui, a direct developing frog, mesendoderm is specified at the marginal zone of the early gastrulae and vegetal core cells transform into nutritional endoderm. It is a novel tissue consisting of transient, yolk rich cells that provide nutrition, but do not differentiate into adult tissues. We hypothesized that a disruption of Nodal-signaling is responsible for committing vegetal core cells to nutritional endoderm. I report a dual regulation involved in the generation of nutritional endoderm. First, differential expression of Nodal-signaling components like Smad2 and Smad4 was observed during early gastrulation between cells in the marginal zone and in the vegetal core. Although EcSmad2 RNA, as well as both native and the active forms of EcSmad2, were detected in the vegetal core by qPCR and western blot respectively, western analysis revealed that Smad4 isoforms were expressed at a low level during early gastrulation. Immunostaining showed that only 12% and 50% of vegetal core cells were positive for nuclear Smad2 and Smad4 signals, respectively, compared to 100% in marginal zone cells. These differential expressions may indicate a signaling blockade in vegetal core cells. Second, I found global transcription repression in vegetal core cells by immunostaining. At late blastula, both the marginal zone and vegetal core cell were transcriptionally silent. At the onset of gastrulation, marginal zone cells, but not vegetal core ones, became transcriptionally active. This indicates the occurrence of a mid-blastula transition in the marginal zone by early gastrulation. Global transcriptional repression prevails in the vegetal core through development. A combination of differential Nodal-signaling and global transcriptional repression in vegetal core cells may account for its lack of differentiation

    HMN: Generalization of Heterogeneous and Multi-layered Network

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    A network may have different types of entities and their relations. Further, there could be additional layers of ties. The former is referred to as Heterogeneous networks, while the latter is known as Multi-layer networks. The present paper provides a generalized network model, namely, a Heterogeneous Multi-layered Network (HMN), which can simultaneously be multi-layered and heterogeneous. The model can represent homogeneous networks as well. We define different structural measures in an HMN. We proved that the sets of all homogeneous, heterogeneous and multi-layered networks are subsets of the set of all HMNs. Accordingly, we established the equivalency of the proposed structural measures of HMNs with that of homogeneous, heterogeneous, and multi-layered networks. Following that, we show how our proposed HMN is more efficient in tasks such as link prediction. In addition, we present a novel parameterized algorithm (with complexity analysis) for generating synthetic HMNs. The networks generated from our proposed algorithm are more consistent in modelling the layer-wise degree distribution of a real-world Twitter network (represented as HMN) than those generated by existing models. Moreover, we also show that our algorithm is more effective in modelling an air-transportation multiplex network when compared to an algorithm designed specifically for the task

    Nonlinear Dynamics, Bifurcation Maps, Signal Encryption and Decryption using Acousto-Optic Chaos under a Variable Aperture Illumination

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    Bragg cell nonlinear dynamics and bifurcation properties under first-order feedback with variable aperture are examined. Chaotic encryption and recovery of low-bandwidth signals, and optimal performance are evaluated for fixed and variable apertures

    Relationship between iron metabolism and thyroid hormone profile in hypothyroidism

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    Background: Iron and thyroid hormone metabolism are closely related with each other. Iron plays an important role for both the synthesis as well as metabolism of thyroid hormones acting as a component of many enzymes including thyroid peroxidase (TPO). So, iron deficiency can lead to abnormal functioning of thyroid gland. Ferritin is storage form of iron in our body. Several studies in showed that nutritional iron deficiency can significantly decrease the circulating levels of both T4 and T3 and it can also reduce peripheral conversion of T4 to T3. So, the aim of the study is to find out whether there is any relationship between hypothyroidism and iron metabolism.Methods: This cross-sectional descriptive study was conducted at Deben Mahata Government Medical College and Hospital, Purulia on 50 hypothyroid patients and 50 age and sex matched controls after imposing inclusion and exclusion criterias. Blood samples were collected and estimation of Serum TSH, fT4 and fT3, iron, ferritin and TIBC levels were done. Then the data obtained were analysed by proper statistical methods.Results: Out of 100 subjects 68 were male and rest were female. The mean serum TSH level in study population was significantly higher than that of comparison group. While serum fT3 and fT4 level in study group were lower than the control group and both were statistically significant. In the other hand, the mean serum ferritin and iron levels in cases were lower than that in controls and the mean TIBS was higher in study group and all the differences were statistically significant. There were significant correlation between Serum ferritin and serum iron (positive correlation), Serum ferritin and TSH (negative correlation), Serum TSH and fT4 (negative correlation) but there was no significant relationship between serum TSH and iron.Conclusions: The iron metabolism is disturbed in hypothyroidism reflected by low serum ferritin and iron