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‣ Characterization of micro-bubble size distribution and flow configuration in DAF contact zone by a non-intrusive image analysis system and tracer tests

MORUZZI, R. B.; REALI, M. A. P.
Fonte: I W A PUBLISHING Publicador: I W A PUBLISHING
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
37.369243%
This paper aims to investigate the influence of some dissolved air flotation (DAF) process variables (specifically: the hydraulic detention time in the contact zone and the supplied dissolved air concentration) and the pH values, as pretreatment chemical variables, on the micro-bubble size distribution (BSD) in a DAF contact zone. This work was carried out in a pilot plant where bubbles were measured by an appropriate non-intrusive image acquisition system. The results show that the obtained diameter ranges were in agreement with values reported in the literature (10-100mm), quite independently of the investigated conditions. The linear average diameter varied from 20 to 30mm, or equivalently, the Sauter (d(3,2)) diameter varied from 40 to 50mm. In all investigated conditions, D(50) was between 75% and 95%. The BSD might present different profile (with a bimodal curve trend), however, when analyzing the volumetric frequency distribution (in some cases with the appearance of peaks in diameters ranging from 90-100mm). Regarding volumetric frequency analysis, all the investigated parameters can modify the BSD in DAF contact zone after the release point, thus potentially causing changes in DAF kinetics. This finding prompts further research in order to verify the effect of these BSD changes on solid particle removal efficiency by DAF.; FAPESP (Fundacao de Amparo a Pesquisa do Estado de Sao Paulo)

‣ Expressão das moléculas reguladoras do sistema complemento, DAF e CD59, no endométrio de mulheres com abortos espontâneos recorrentes; Expression of Complement Regulatory Proteins, DAF e CD59, in endometrium of women with recurrent spontaneous abortion

Andozia, Mayra Beraldo
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 03/07/2009 Português
Relevância na Pesquisa
37.592405%
Durante o ciclo menstrual, o endométrio se torna receptivo à chegada do "futuro embrião". Estes eventos são regulados pela liberação de progesterona durante a fase secretória do ciclo, que aumenta a secreção do componente C3 do Sistema Complemento (SC). Neste período, também foi observado o aumento fisiológico da expressão de algumas proteínas reguladoras do SC (CRPs) como: C1Inh, C4bp, DAF, CD59 e clusterina, oque sugere uma forte regulação da atividade deste sistema, favorável à implantação e ao desenvolvimento embrionário. Modificações na expressão destas proteínas poderiam resultar em aborto espontâneo recorrente (AER).Neste trabalho estudou-se a expressão endometrial de DAF e CD59 noendométrio de pacientes com AER, durante a fase secretória do ciclo. Adicionalmente, verificou-se a ativação do SC através da presença do neoantígeno de C9 neste mesmo material. A casuística foi composta de nove mulheres férteis normais (Grupo Controle) e doze mulheres com AER (Grupo Aborto), todas analisadas durante a fase secretória do ciclo. A técnica utilizada para detecção destas proteínas foi a imunohistoquímica. O neoantígeno deC9 não foi detectado em nenhum dos grupos, tanto nas glândulas quanto no estroma endometrial. DAF e CD59 foram detectados tanto no Grupo Controle quanto no Grupo Aborto.Houve expressão nitidamente mais acentuada de ambas as CRPs...

‣ Characterization of micro-bubble size distribution and flow configuration in DAF contact zone by a non-intrusive image analysis system and tracer tests

Moruzzi, R. B.; Reali, M. A. P.
Fonte: I W A Publishing Publicador: I W A Publishing
Tipo: Artigo de Revista Científica Formato: 253-262
Português
Relevância na Pesquisa
37.369243%
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); This paper aims to investigate the influence of some dissolved air flotation (DAF) process variables (specifically: the hydraulic detention time in the contact zone and the supplied dissolved air concentration) and the pH values, as pretreatment chemical variables, on the micro-bubble size distribution (BSD) in a DAF contact zone. This work was carried out in a pilot plant where bubbles were measured by an appropriate non-intrusive image acquisition system. The results show that the obtained diameter ranges were in agreement with values reported in the literature (10-100mm), quite independently of the investigated conditions. The linear average diameter varied from 20 to 30mm, or equivalently, the Sauter (d(3,2)) diameter varied from 40 to 50mm. In all investigated conditions, D(50) was between 75% and 95%. The BSD might present different profile (with a bimodal curve trend), however, when analyzing the volumetric frequency distribution (in some cases with the appearance of peaks in diameters ranging from 90-100mm). Regarding volumetric frequency analysis, all the investigated parameters can modify the BSD in DAF contact zone after the release point, thus potentially causing changes in DAF kinetics. This finding prompts further research in order to verify the effect of these BSD changes on solid particle removal efficiency by DAF.

‣ Daf-2, Daf-16 and Daf-23: Genetically Interacting Genes Controlling Dauer Formation in Caenorhabditis Elegans

Gottlieb, S.; Ruvkun, G.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /05/1994 Português
Relevância na Pesquisa
27.671968%
Under conditions of high population density and low food, Caenorhabditis elegans forms an alternative third larval stage, called the dauer stage, which is resistant to desiccation and harsh environments. Genetic analysis of some dauer constitutive (Daf-c) and dauer defective (Daf-d) mutants has revealed a complex pathway that is likely to function in particular neurons and/or responding tissues. Here we analyze the genetic interactions between three genes which comprise a branch of the dauer formation pathway that acts in parallel to or downstream of the other branches of the pathway, the Daf-c genes daf-2 and daf-23 and the Daf-d gene daf-16. Unlike mutations in other Daf-c genes, mutations in both daf-2 and daf-23 cause non-conditional arrest at the dauer stage. Our epistasis analysis suggests that daf-2 and daf-23 are functioning at a similar point in the dauer pathway. First, mutations in daf-2 and daf-23 are epistatic to mutations in the same set of Daf-d genes. Second, daf-2 and daf-23 mutants are suppressed by mutations in daf-16. Mutations in daf-16 do not suppress any of the other Daf-c mutants as efficiently as they suppress daf-2 and daf-23 mutants. Third, double mutants between either daf-2 or daf-23 and several other daf-d mutants exhibit an unusual interaction. Based on these results...

‣ Two pleiotropic classes of daf-2 mutation affect larval arrest, adult behavior, reproduction and longevity in Caenorhabditis elegans.

Gems, D; Sutton, A J; Sundermeyer, M L; Albert, P S; King, K V; Edgley, M L; Larsen, P L; Riddle, D L
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /09/1998 Português
Relevância na Pesquisa
27.63184%
The nematode Caenorhabditis elegans responds to overcrowding and scarcity of food by arresting development as a dauer larva, a nonfeeding, long-lived, stress-resistant, alternative third-larval stage. Previous work has shown that mutations in the genes daf-2 (encoding a member of the insulin receptor family) and age-1 (encoding a PI 3-kinase) result in constitutive formation of dauer larvae (Daf-c), increased adult longevity (Age), and increased intrinsic thermotolerance (Itt). Some daf-2 mutants have additional developmental, behavioral, and reproductive defects. We have characterized in detail 15 temperature-sensitive and 1 nonconditional daf-2 allele to investigate the extent of daf-2 mutant defects and to examine whether specific mutant traits correlate with each other. The greatest longevity seen in daf-2 mutant adults was approximately three times that of wild type. The temperature-sensitive daf-2 mutants fell into two overlapping classes, including eight class 1 mutants, which are Daf-c, Age, and Itt, and exhibit low levels of L1 arrest at 25.5 degrees. Seven class 2 mutants also exhibit the class 1 defects as well as some or all of the following: reduced adult motility, abnormal adult body and gonad morphology, high levels of embryonic and L1 arrest...

‣ Characterization of glycosylphosphatidylinositol-anchored decay accelerating factor (GPI-DAF) and transmembrane DAF gene expression in wild-type and GPI-DAF gene knockout mice using polyclonal and monoclonal antibodies with dual or single specificity

Miwa, Takashi; Sun, Xiujun; Ohta, Rieko; Okada, Noriko; Harris, Claire L; Morgan, B Paul; Song, Wen-Chao
Fonte: Blackwell Science Inc Publicador: Blackwell Science Inc
Tipo: Artigo de Revista Científica
Publicado em /10/2001 Português
Relevância na Pesquisa
27.652954%
Decay-accelerating factor (DAF, CD55) is a glycosylphosphatidylinositol (GPI)-linked membrane inhibitor of complement activation. While human and other mammalian species contain only one DAF gene, two distinct DAF genes, referred to as GPI-DAF and transmembrane (TM)-DAF, respectively, have been identified in the mouse. Using several independently generated monoclonal and polyclonal antibodies, either with dual or single specificity for GPI-DAF and TM-DAF gene products, we have examined the expression of the two DAF genes in tissues of the wild-type and a strain of knockout mouse whose GPI-DAF gene has been inactivated. By fluorescence-activated cell sorting (FACS) analysis, we found that DAF protein is present on the wild-type mouse erythrocytes and lymphocytes but no signal was detectable on the same cells of GPI-DAF gene knockout mice. Both T and B lymphocytes and splenic macrophages express the GPI-DAF gene but the expression level is higher on B lymphocytes than on T lymphocytes. Within the T cell population, both CD4+ and CD8+ T cells are positive. DAF protein was detected by immunohistochemistry at high levels on wild-type mouse spermatids and mature sperm. In contrast, only mature sperm stained positive in the GPI-DAF gene knockout mouse testis...

‣ Inhibition of complement activation on the surface of cells after incorporation of decay-accelerating factor (DAF) into their membranes

Fonte: The Rockefeller University Press Publicador: The Rockefeller University Press
Tipo: Artigo de Revista Científica
Publicado em 01/11/1984 Português
Relevância na Pesquisa
27.610522%
Decay-accelerating factor (DAF), extracted from the stroma of human erythrocytes, was purified to homogeneity and incorporated into the membrane of sheep red cell complement intermediates, where its functional properties were analyzed. Incorporation of DAF into the cell membranes was temperature dependent, took place on pronase- or trypsin- treated erythrocytes, and did not depend on prior deposition of antibody, C1 or C4. Serum lipoproteins (high and low density) effectively inhibited DAF incorporation, but had no effect on the activity of DAF after its association with the cell membrane. The incorporated DAF could not be removed from the red cell surface by repeated washings in the presence of high salt concentration but was solubilized when the stroma were extracted with 0.1% Nonidet P-40. The presence of DAF in the membrane of EA did not affect the deposition of C1 and C4, but as few as 10(2) DAF molecules per cell profoundly inhibited the assembly of C3 and C5 convertases of both the classical and alternative pathways. The DAF inhibitory effect on EAC14 or EAC43 was not overcome by supplying an excess of C2 or factor B, but the alternative pathway C3 convertase could be assembled in the presence of Ni++, or nonphysiological concentrations of Mg++...

‣ Identification of the complement decay-accelerating factor (DAF) on epithelium and glandular cells and in body fluids

Fonte: The Rockefeller University Press Publicador: The Rockefeller University Press
Tipo: Artigo de Revista Científica
Publicado em 01/03/1987 Português
Relevância na Pesquisa
27.601934%
Decay-accelerating factor (DAF) is a 70 kD membrane regulatory protein that prevents the activation of autologous complement on cell surfaces. Using immunohistochemical methods and a radioimmunometric assay based on mAbs to DAF, we found large amounts of membrane-associated DAF antigen on the epithelial surface of cornea, conjunctiva, oral and gastrointestinal mucosa, exocrine glands, renal tubules, ureter and bladder, cervical and uterine mucosa, and pleural, pericardial and synovial serosa. Additionally, we detected soluble DAF antigen in plasma, tears, saliva, and urine, as well as in synovial and cerebrospinal fluids. While plasma, tear, and saliva DAF are larger than erythrocyte (Ehu) membrane DAF by Western blot analysis, urine DAF is slightly smaller (67,000) in Mr. Unlike purified Ehu DAF, however, urine DAF is unable to incorporate into the membrane of red cells. Although its inhibitory activity on the complement enzyme C3-convertase is lower than that of Ehu DAF, it is comparable to that of serum C4 binding protein (C4bp). Biosynthetic studies using cultured foreskin epithelium and Hela cells disclosed DAF levels (approximately 2 X 10(5) molecules/cell) exceeding those on blood cells. In addition, these studies revealed the synthesis of two DAF species...

‣ Structural and functional characterisation of the fork head transcription factor-encoding gene, Hc-daf-16, from the parasitic nematode Haemonchus contortus (Strongylida)

Hu, Min; Lok, James B.; Ranjit, Najju; Massey, Holman C.; Sternberg, Paul W.; Gasser, Robin B.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
27.592405%
Despite their phylogenetic diversity, parasitic nematodes share attributes of longevity and developmental arrest (=hypobiosis) with free-living nematodes at key points in their life cycles, particularly in larval stages responsible for establishing infection in the host. Insulin-like signalling plays crucial roles in the regulation of life span and arrest (=dauer formation) in the free-living nematode, Caenorhabditis elegans. Insulin-like signalling in C. elegans negatively regulates the fork head boxO (FoxO) transcription factor encoded by daf-16, which is linked to initiating a dauer-specific pattern of gene expression. Orthologues of daf-16 have been identified in several species of parasitic nematode. Although function has been demonstrated for an orthologue from the parasitic nematode Strongyloides stercoralis (Rhabditida), the functional capabilities of homologues/orthologues in bursate nematodes (Strongylida) are unknown. In the present study, we used a genomic approach to determine the structures of two complete daf-16 orthologues (designated Hc-daf-16.1 and Hc-daf-16.2) and their transcripts in the parasitic nematode Haemonchus contortus, and assessed their function(s) using C. elegans as a genetic surrogate. Unlike the multiple isoforms of Ce-DAF-16 and Ss-DAF-16...

‣ Transgenic C. elegans Dauer Larvae Expressing Hookworm Phospho Null DAF-16/FoxO Exit Dauer

Gelmedin, Verena; Brodigan, Thomas; Gao, Xin; Krause, Michael; Wang, Zhu; Hawdon, John M.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 07/10/2011 Português
Relevância na Pesquisa
27.592405%
Parasitic hookworms and the free-living model nematode Caenorhabtidis elegans share a developmental arrested stage, called the dauer stage in C. elegans and the infective third-stage larva (L3) in hookworms. One of the key transcription factors that regulate entrance to and exit from developmental arrest is the forkhead transcription factor DAF-16/FoxO. During the dauer stage, DAF-16 is activated and localized in the nucleus. DAF-16 is negatively regulated by phosphorylation by the upstream kinase AKT, which causes DAF-16 to localize out of the nucleus and the worm to exit from dauer. DAF-16 is conserved in hookworms, and hypothesized to control recovery from L3 arrest during infection. Lacking reverse genetic techniques for use in hookworms, we used C. elegans complementation assays to investigate the function of Ancylostoma caninum DAF-16 during entrance and exit from L3 developmental arrest. We performed dauer switching assays and observed the restoration of the dauer phenotype when Ac-DAF-16 was expressed in temperature-sensitive dauer defective C. elegans daf-2(e1370);daf-16(mu86) mutants. AKT phosphorylation site mutants of Ac-DAF-16 were also able to restore the dauer phenotype, but surprisingly allowed dauer exit when temperatures were lowered. We used fluorescence microscopy to localize DAF-16 during dauer and exit from dauer in C. elegans DAF-16 mutant worms expressing Ac-DAF-16...

‣ The fork head transcription factor FKTF-1b from Strongyloides stercoralis restores DAF-16 developmental function to mutant Caenorhabditis elegans

Massey, Holman C.; Bhopale, Mahendra K.; Li, Xinshe; Castelletto, Michelle; Lok, James B.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
27.592405%
The purpose of this study was to determine whether Strongyloides stercoralis FKTF-1, a transcription factor of the FOXO/FKH family and the likely output of insulin/IGF signal transduction in that parasite, has the same or similar developmental regulatory capabilities as DAF-16, its structural ortholog in Caenorhabditis elegans. To this end, both splice variants of the fktf-1 message were expressed under the control of the daf-16α promoter in C. elegans carrying loss of function mutations in both daf-2 (the insulin/IGF receptor kinase) and daf-16. Under well-fed culture conditions the majority (91%) of untransformed daf-2; daf-16 double mutants developed via the continuous reproductive cycle, whereas under the same conditions 100% of daf-2 single mutants formed dauers. Transgenic daf-2; daf-16 individuals expressing fktf-1b showed a reversal of the double mutant phenotype with 75% of the population forming dauers under well-fed conditions. This phenotype was even more pronounced than that of daf-2; daf-16 mutants transformed with a homologous rescuing construct, daf-16α::daf-16a (56% dauers under well fed conditions), indicating that S. stercoralis fktf-1b can almost fully rescue loss-of-function mutants in C. elegans daf-16. By contrast...

‣ Variabilidade genética em populações de Ricinus communis (Euphorbiaceae) pela metodologia de DAF (DNA Amplification Fingerprinting

Santana de Oliveira, Nilmara; Maria Benko Iseppon, Ana (Orientador)
Fonte: Universidade Federal de Pernambuco Publicador: Universidade Federal de Pernambuco
Tipo: Outros
Português
Relevância na Pesquisa
36.982427%
O Brasil ocupa mundialmente a terceira posição na produção de mamona (Ricinus communis L.). Embora existam muitos estudos moleculares voltados às proteínas expressas nas sementes, não existem até o momento análises com marcadores moleculares avaliando a diversidade genética dessa espécie. O presente trabalho estudou a variabilidade genética de 16 genótipos de populações subespontâneas de mamona adquiridas através de coletas em quatro diferentes localidades de Pernambuco e em duas outras regiões do Brasil, comparando-as a acessos cultivados de quatro outros países. Para isso a metodologia de DAF (DNA amplification Fingerprinting) foi utilizada, permitindo a geração de em média 14 bandas por primer, sendo 10,72 polimórficas, a partir de 11 primers. Para a construção da matriz de dados 143 bandas foram analisadas, perfazendo 2.288 caracteres. A análise filogenética de máxima parsimônia revelou uma diversidade genética significativa, entre genótipos da mesma população, considerando os diferentes pontos de coleta no Brasil, bem como comparativamente com acessos cultivados no exterior. O estudo confirma a variabilidade sugerida pelos melhoristas para as populações subespontâneas de mamona e demonstra a eficiência deste tipo de marcador para estudos de caracterização de germoplasma desta importante cultura vegetal.

‣ Characterization of the Caenorhabditis elegans daf-18/PTEN genetic pathway: germline proliferation and failure of L1 developmental arrest as models for PTEN roles in cancer

Salmers, Gabrielle K
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado Formato: 646443 bytes; application/pdf
Português
Relevância na Pesquisa
37.238223%
Cancer ultimately results from the abnormal regulation of genes and proteins involved in developmental processes. By detailing developmental pathways it is possible to determine which genes are responsible for the production of cancerous phenotypes and what is responsible for their corruption. PTEN is a human tumour suppressor, commonly found mutated in cancers. The PTEN homologue in Caenorhabditis elegans is called DAF-18 and is necessary for successful developmental arrest when embryos are hatched into unfavourable conditions. Through investigating the effects of somatic versus germline expression of daf-18 in L1 arrest and specific knockdown of homologues of candidate cancer genes (CANgenes), this study aims to characterize the daf-18/PTEN pathway and determine the role of this gene in development. Although C. elegans does not get cancer per se, this will provide clues on how human PTEN functions with potential CANgenes.

‣ daf-18 as a tumour suppressor during L1 arrest and germline development in Caenorhabditis elegans

Peng, Jimmy
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
37.44888%
Model organisms provide a useful tool for the study of human cancer genes. The human PTEN gene is the second-most commonly lost tumour suppressor in cancers, and its ortholog is DAF-18 in Caenorhabditis elegans. This study characterized phenotypes of daf-18 mutants in C. elegans that give insight to its tumour-suppressor properties. First, a small proportion (1%) of daf-18 mutants show abnormal proliferation of somatic cells during the L1 larval arrest stage, when cells normally remain quiescent. daf-18 mutants also die early during L1 arrest (maximum lifespan of 3 days vs. 20+ days in wild-type), which is partially suppressed by a vab-1 mutation or the transgenic somatic expression of DAF-18 (6 and 7 day max lifespan, respectively). Finally, daf-18 animals show abnormal germline development under normal growth conditions. This study provides useful phenotypes that can be used for future screens to find other interactors of DAF-18 and genes that are involved in L1 arrest.

‣ Tissue Specific Functions and Regulation of DAF-18/PTEN

Chamberlain, GABRIEL
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
37.478032%
The insulin signaling antagonist daf-18/PTEN is known to play various roles in the response of C. elegans to starvation. While daf-18’s roles in promoting dauer formation are well understood, the extent of its roles in L1 arrest remains unclear. Recent studies have highlighted the importance of germline expression of daf-18 in coordinating proper L1 arrest. It had been previously hypothesized that germline expressed daf-18 might be sufficient to properly arrest germline proliferation and achieve wildtype levels of L1 arrest longevity. In this study, I show that germline expression alone is neither sufficient in restoring full L1 arrest longevity nor germ cell quiescence. Instead, L1 arrest longevity is dependent on systemic daf-18 expression. I also explore the effects of maternal contributions to offspring on L1 arrest longevity. I show here that maternally rescued daf-18 mutants survive two days longer than controls. I demonstrate that worms that progressed to adulthood through the dauer life stage do not produce offspring that are better suited to survive L1 arrest. Conversely, I observed adult worms that experience crowding produce offspring with mildly increased L1 arrest longevity. Lastly, I explore the post- translational regulation of DAF-18 by demonstrating that the proteasomal subunits pas-3 and pbs-4 are involved in DAF-18 degradation.; Thesis (Master...

‣ Exploring the Functional Significance of the Caenorhabditis elegans VAB-1 Eph RTK and DAF-18/PTEN Tumour Suppressor Interaction

Brisbin, SARAH
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado Formato: 15394328 bytes; application/pdf
Português
Relevância na Pesquisa
37.540857%
The Caenorhabditis elegans Eph RTK, VAB-1, has known roles in neuronal and epidermal morphogenesis as well as oocyte maturation through interaction with its ephrin ligands. In humans, Eph receptors are involved in nervous and vascular system development and have been implicated in cancer formation and progression. DAF-18, a C. elegans ortholog of the human tumour suppressor gene, PTEN, has been identified as an interacting partner with the Eph RTK, VAB-1. Mutations in human PTEN have been associated with numerous cancers and in the worm, DAF-18 is a well studied member of the DAF-2/Insulin receptor-like signaling pathway which has roles in dauer formation, thermotolerance and adult longevity. Our lab has previously shown that VAB-1/EphR binds DAF-18. To further investigate the significance of this interaction as well as offer additional function to the proteins involved, I have shown that VAB-1/EphR is a negative regulator of DAF-18/PTEN at the protein level. Western blotting reveals that endogenous expression of DAF-18/PTEN is low in wild-type animals and expression is increased in a vab-1/ephR mutant. Additionally, VAB-1/EphR and DAF-18/PTEN are expressed in head neurons, oocytes and the germline precursor cells, Z2/Z3. vab-1/ephR mutants show increases longevity and sensitivity to dauer conditions which is consistent with increased DAF-18/PTEN activity. Lastly...

‣ Hc-daf-2 encodes an insulin-like receptor kinase in the barber's pole worm, Haemonchus contortus, and restores partial dauer regulation

Li, Facai; Lok, James B.; Gasser, Robin B.; Korhonen, Pasi K.; Sandeman, Mark R.; Shi, Deshi; Zhou, Rui; Li, Xiangrui; Zhou, Yanqin; Zhao, Junlong; Hu, Min
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
27.592405%
Infective L3s (iL3s) of parasitic nematodes share common behavioural, morphological and developmental characteristics with the developmentally arrested (dauer) larvae of the free-living nematode Caenorhabditis elegans. It is proposed that similar molecular mechanisms regulate entry into or exit from the dauer stage in C. elegans, and the transition from free-living to parasitic forms of parasitic nematodes. In C elegans, one of the key factors regulating the dauer transition is the insulin-like receptor (designated Ce-DAF-2) encoded by the gene Ce-daf-2. However, nothing is known about DAF-2 homologues in most parasitic nematodes. Here, using a PCR-based approach, we identified and characterised a gene (Hc-daf-2) and its inferred product (Hc-DAF-2) in Haemonchus contortus (a socioeconomically important parasitic nematode of ruminants). The sequence of Hc-DAF-2 displays significant sequence homology to insulin receptors (IR) in both vertebrates and invertebrates, and contains conserved structural domains. A sequence encoding an important proteolytic motif (RKRR) identified in the predicted peptide sequence of Hc-DAF-2 is consistent with that of the human IR, suggesting that it is involved in the formation of the IR complex. The Hc-daf-2 gene was transcribed in all life stages of H. contortus...

‣ Longevity Genes Revealed by Integrative Analysis of Isoform-Specific daf-16/FoxO Mutants of Caenorhabditis elegans

Chen, Albert Tzong-Yang; Guo, Chunfang; Itani, Omar A.; Budaitis, Breane G.; Williams, Travis W.; Hopkins, Christopher E.; McEachin, Richard C.; Pande, Manjusha; Grant, Ana R.; Yoshina, Sawako; Mitani, Shohei; Hu, Patrick J.
Fonte: Genetics Society of America Publicador: Genetics Society of America
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
27.592405%
FoxO transcription factors promote longevity across taxa. How they do so is poorly understood. In the nematode Caenorhabditis elegans, the A- and F-isoforms of the FoxO transcription factor DAF-16 extend life span in the context of reduced DAF-2 insulin-like growth factor receptor (IGFR) signaling. To elucidate the mechanistic basis for DAF-16/FoxO-dependent life span extension, we performed an integrative analysis of isoform-specific daf-16/FoxO mutants. In contrast to previous studies suggesting that DAF-16F plays a more prominent role in life span control than DAF-16A, isoform-specific daf-16/FoxO mutant phenotypes and whole transcriptome profiling revealed a predominant role for DAF-16A over DAF-16F in life span control, stress resistance, and target gene regulation. Integration of these datasets enabled the prioritization of a subset of 92 DAF-16/FoxO target genes for functional interrogation. Among 29 genes tested, two DAF-16A-specific target genes significantly influenced longevity. A loss-of-function mutation in the conserved gene gst-20, which is induced by DAF-16A, reduced life span extension in the context of daf-2/IGFR RNAi without influencing longevity in animals subjected to control RNAi. Therefore, gst-20 promotes DAF-16/FoxO-dependent longevity. Conversely...

‣ Structural and functional characterisation of the fork head transcription factor-encoding gene, Hc-daf-16, from the parasitic nematode Haemonchus contortus (Strongylida)

Hu, Min; Lok, James B.; Ranjit, Najju; Massey, Holman C., Jr.; Sternberg, Paul W.; Gasser, Robin B.
Fonte: Elsevier Publicador: Elsevier
Tipo: Article; PeerReviewed Formato: application/pdf
Publicado em 15/03/2010 Português
Relevância na Pesquisa
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Despite their phylogenetic diversity, parasitic nematodes share attributes of longevity and developmental arrest (=hypobiosis) with free-living nematodes at key points in their life cycles, particularly in larval stages responsible for establishing infection in the host. Insulin-like signalling plays crucial roles in the regulation of life span and arrest (=dauer formation) in the free-living nematode, Caenorhabditis elegans. Insulin-like signalling in C. elegans negatively regulates the fork head boxO (FoxO) transcription factor encoded by daf-16, which is linked to initiating a dauer-specific pattern of gene expression. Orthologues of daf-16 have been identified in several species of parasitic nematode. Although function has been demonstrated for an orthologue from the parasitic nematode Strongyloides stercoralis (Rhabditida), the functional capabilities of homologues/orthologues in bursate nematodes (Strongylida) are unknown. In the present study, we used a genomic approach to determine the structures of two complete daf-16 orthologues (designated Hc-daf-16.1 and Hc-daf-16.2) and their transcripts in the parasitic nematode Haemonchus contortus, and assessed their function(s) using C. elegans as a genetic surrogate. Unlike the multiple isoforms of Ce-DAF-16 and Ss-DAF-16...

‣ „Viel Lärm um nichts?“ Fachsprachenlehrwerke im Spannungsfeld zwischen Theorie und Praxis. Eine vergleichende Analyse berufs- und fachbezogener DaF-Lehrwerke aus dem Bereich Wirtschaft; „Viel Lärm um nichts?“ Fachsprachenlehrwerke im Spannungsfeld zwischen Theorie und Praxis. Eine vergleichende Analyse berufs- und fachbezogener DaF-Lehrwerke aus dem Bereich Wirtschaft; „Viel Lärm um nichts?“ Fachsprachenlehrwerke im Spannungsfeld zwischen Theorie und Praxis. Eine vergleichende Analyse berufs- und fachbezogener DaF-Lehrwerke aus dem Bereich Wirtschaft

Groß, Claudia
Fonte: Universidade de São Paulo. Faculdade de Filosofia, Letras e Ciências Humanas Publicador: Universidade de São Paulo. Faculdade de Filosofia, Letras e Ciências Humanas
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; ; ; ; ; Formato: application/pdf
Publicado em 06/06/2009 Português
Relevância na Pesquisa
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A partir da análise comparativa de obras didáticas de DaF (= Deutsch als Fremdsprache: Alemão como Língua Estrangeira) das áreas de “alemão para economistas” e de “alemão para profissionais”, este trabalho investiga até que ponto obras didáticas para o ensino da linguagem comum se distinguem de obras didáticas para o ensino de linguagens técnico-científicas. Além das diferenças e das semelhanças das obras didáticas analisadas, esta pesquisa mostra também os problemas surgidos das necessidades específicas de obras didáticas para o ensino de linguagens técnico-científicas. Os resultados da pesquisa apontam que, embora existam diferenças entre a concepção das obras didáticas para o ensino da linguagem comum e aquelas para o ensino de linguagem técnico-científica, na prática, essas diferenças são insignificantes.; Anhand einer vergleichenden Analyse von DaF-Lehrwerken aus dem Bereich „Wirtschaftsdeutsch“ und „Berufsdeutsch“ wird der Frage nachgegangen, inwiefern sich gemeinsprachliche und fachsprachliche Lehrwerke voneinander unterscheiden. Dabei werden nicht nur Unterschiede bzw. Gemeinsamkeiten sichtbar gemacht, sondern auch Probleme aufgezeigt, die sich aus den besonderen Anforderungen an Fachsprachenlehrwerke ergeben. Die Ergebnisse der Untersuchung weisen darauf hin...