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Hormonal Signals (hormonal + signal)
Selected AbstractsATP allosteric activation of atrial natriuretic factor receptor guanylate cyclaseFEBS JOURNAL, Issue 11 2010Teresa Duda Atrial natriuretic factor receptor guanylate cyclase (ANF-RGC) is the receptor and the signal transducer of two natriuretic peptide hormones: atrial natriuretic factor and brain natriuretic peptide. It is a single transmembrane-spanning protein. It binds these hormones at its extracellular domain and activates its intracellular catalytic domain. This results in the accelerated production of cyclic GMP, a second messenger in controlling blood pressure, cardiac vasculature and fluid secretion. ATP is obligatory for the transduction of this hormonal signal. Two models of ATP action have been proposed. In Model 1, it is a direct allosteric transducer. It binds to the defined regulatory domain (ATP-regulated module) juxtaposed to the C-terminal side of the transmembrane domain of ANF-RGC, induces a cascade of temporal and spatial changes and activates the catalytic module residing at the C-terminus of the cyclase. In Model 2, before ATP can exhibit its allosteric effect, ANF-RGC must first be phosphorylated by an as yet unidentified protein kinase. This initial step is obligatory in atrial natriuretic factor signaling of ANF-RGC. Until now, none of these models has been directly validated because it has not been possible to segregate the allosteric and the phosphorylation effects of ATP in ANF-RGC activation. The present study accomplishes this aim through a novel probe, staurosporine. This unequivocally validates Model 1 and settles the over two-decade long debate on the role of ATP in ANF-RGC signaling. In addition, the present study demonstrates that the mechanisms of allosteric modification of ANF-RGC by staurosporine and adenylyl-imidodiphosphate, a nonhydrolyzable analog of ATP, are almost (or totally) identical. [source] Pigmentation development in hatchery-reared flatfishesJOURNAL OF FISH BIOLOGY, Issue 5 2000J. A. Bolker Malpigmentation is common in hatchery-reared flatfishes, decreasing the market value of whole fish, and increasing the risk of predation for juveniles released to enhance wild stocks. Pigmentation development in flatfishes occurs in two phases. First, during embryonic and larval stages pigment cells differentiate on both sides of the body. Second, at metamorphosis larval melanophores disappear, and adult melanophores differentiate on the ocular but not on the blind side. Malpigmentation seems to result from disruptions of the second phase, and may take the form of albinism on the ocular side or darkening of the blind side. Both types of aberration may be related to aspects of the hatchery environment such as lighting, substratum, and diet. Larval nutrition appears to be a key factor and enrichment of larval diets with fatty acids and Vitamin A can greatly reduce malpigmentation rates; however, levels suffcient to prevent pigmentation defects frequently cause other abnormalities. Two developmental explanations for albinism have been proposed. The first is that differentiation of ocular-side skin follows the normal blind-side pathway and adult melanophores therefore fail to develop on the ocular side. The second hypothesis suggests that dietary deficiencies inhibit retinal development and the resulting visual defects lead to failure of a hormonal signal required for melanophore differentiation. These hypotheses may well be complementary; as yet neither has been thoroughly tested. Definitive tests will require a combination of manipulative techniques such as tissue transplantation and cell culture with nutritional, behavioural and hormonal assays. Such integrative studies will further the understanding both of normal pigmentation development and of the environmental factors that contribute to high rates of albinism in hatchery-reared flatfish. [source] The effects of polychlorinated biphenyls (Aroclor 1242) on thyroxine, estradiol, molt, and plumage characteristics in the American kestrel (Falco sparverius)ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2002Michael J. Quinn Jr. Abstract The purpose of this experiment was to determine the effects of Aroclor 1242, a mixture of polychlorinated biphenyls (PCBs), on plumage characteristics and molt in the American kestrel, Falco sparverius. Several characteristics of plumage, including color and molt schedule, are modulated by hormonal signals and hence may be modified by endocrine-active contaminants. If so, the functions of plumage (e.g., communication for mating or territorial defense) may be compromised by exposure to such compounds. Captive American kestrels were fed Aroclor 1242 at 0, 6.0, and 60.0 ppm (n = 6 males and 6 females per treatment) mixed in their normal diet. Concentrations of plasma estradiol and thyroxine were measured weekly from the beginning of treatment. Measured plumage characteristics included width of the black subterminal band on the tail, color (a composite index of hue and saturation), reflectance from 230 to 800 nm, pattern of feather loss and regrowth on the tail and wing, and timing of onset and duration of molt. Aroclor 1242 depressed plasma thyroxine. Plasma estradiol levels remained low due to the phase of the breeding cycle. Treatments did not disrupt the measured plumage characteristics. This may be due to timing or dose of exposure or to genetic factors. [source] The Heterotrimeric G-protein Complex Modulates Light Sensitivity in Arabidopsis thaliana Seed GerminationPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2009Javier F. Botto Release of dormancy and induction of seed germination are complex traits finely regulated by hormonal signals and environmental cues such as temperature and light. The Red (R):Far-Red (FR) phytochrome photoreceptors mediate light regulation of seed germination. We investigated the possible involvement of heterotrimeric G-protein complex in the phytochrome signaling pathways of Arabidopsis thaliana seed germination. Germination rates of null mutants of the alpha (G,) and beta (G,) subunits of the G-protein (Atgpa1-4 and agb1-2, respectively) and the double mutant (agb1-2/gpa1-4) are lower than the wildtype (WT) under continuous or pulsed light. The G, and G, subunits play a role in seed germination under hourly pulses of R lower than 0.1 ,mol m,2 s,1 whereas the G, subunit plays a role in higher R fluences. The germination of double mutants of G-protein subunits with phyA-211 and phyB-9 suggests that AtGPA1 seems to act as a positive regulator of phyA and probably phyB signaling pathways, while the role of AGB1 is ambiguous. The imbibition of seeds at 4°C and 35°C alters the R and FR light responsiveness of WT and G-protein mutants to a similar magnitude. Thus, G, and G, subunits of the heterotrimeric G-protein complex modulate light induction of seed germination by phytochromes and are dispensable for the control of dormancy by low and high temperatures prior to irradiation. We discuss the possible indirect role of the G-protein complex on the phytochrome-regulated germination through hormonal signaling pathways. [source] Comparative physiology of salt and water stressPLANT CELL & ENVIRONMENT, Issue 2 2002R. Munns Abstract Plant responses to salt and water stress have much in common. Salinity reduces the ability of plants to take up water, and this quickly causes reductions in growth rate, along with a suite of metabolic changes identical to those caused by water stress. The initial reduction in shoot growth is probably due to hormonal signals generated by the roots. There may be salt-specific effects that later have an impact on growth; if excessive amounts of salt enter the plant, salt will eventually rise to toxic levels in the older transpiring leaves, causing premature senescence, and reduce the photosynthetic leaf area of the plant to a level that cannot sustain growth. These effects take time to develop. Salt-tolerant plants differ from salt-sensitive ones in having a low rate of Na+ and Cl, transport to leaves, and the ability to compartmentalize these ions in vacuoles to prevent their build-up in cytoplasm or cell walls and thus avoid salt toxicity. In order to understand the processes that give rise to tolerance of salt, as distinct from tolerance of osmotic stress, and to identify genes that control the transport of salt across membranes, it is important to avoid treatments that induce cell plasmolysis, and to design experiments that distinguish between tolerance of salt and tolerance of water stress. [source] REVIEW ARTICLE: The Interface of the Immune and Reproductive Systems in the Ovary: Lessons Learned from the Corpus Luteum of Domestic Animal ModelsAMERICAN JOURNAL OF REPRODUCTIVE IMMUNOLOGY, Issue 4 2010Joy L. Pate Citation Pate JL, Toyokawa K, Walusimbi S, Brzezicka E. The interface of the immune and reproductive systems in the ovary: lessons learned from the corpus luteum of domestic animal models. Am J Reprod Immunol 2010 The dynamic changes that characterize the female reproductive system are regulated by hormones. However, local cell-to-cell interactions may mediate responsiveness of tissues to hormonal signals. The corpus luteum (CL) is an excellent model for understanding how immune cells are recruited into tissues and the role played by those cells in regulating tissue homeostasis or demise. Leukocytes are recruited into the CL throughout its lifespan, and leukocyte-derived cytokines have been found in corpora lutea of all species examined. The proinflammatory cytokines inhibit gonadotropin-stimulated steroidogenesis, profoundly stimulate prostaglandin synthesis by luteal cells, and promote apoptosis. However, there is mounting evidence that leukocytes and luteal cells communicate in different ways to maintain homeostasis within the functional CL. Domestic animals have provided important information regarding the presence and role of immune cells in the CL. [source] Environmental and hormonal regulation of the activity,dormancy cycle in the cambial meristem involves stage-specific modulation of transcriptional and metabolic networksTHE PLANT JOURNAL, Issue 4 2007Nathalie Druart Summary We have performed transcript and metabolite profiling of isolated cambial meristem cells of the model tree aspen during the course of their activity,dormancy cycle to better understand the environmental and hormonal regulation of this process in perennial plants. Considerable modulation of cambial transcriptome and metabolome occurs throughout the activity,dormancy cycle. However, in addition to transcription, post-transcriptional control is also an important regulatory mechanism as exemplified by the regulation of cell-cycle genes during the reactivation of cambial cell division in the spring. Genes related to cold hardiness display temporally distinct induction patterns in the autumn which could explain the step-wise development of cold hardiness. Factors other than low temperature regulate the induction of early cold hardiness-related genes whereas abscisic acid (ABA) could potentially regulate the induction of late cold hardiness-related genes in the autumn. Starch breakdown in the autumn appears to be regulated by the ,short day' signal and plays a key role in providing substrates for the production of energy, fatty acids and cryoprotectants. Catabolism of sucrose and fats provides energy during the early stages of reactivation in the spring, whereas the reducing equivalents are generated through activation of the pentose phosphate shunt. Modulation of gibberellin (GA) signaling and biosynthesis could play a key role in the regulation of cambial activity during the activity,dormancy cycle as suggested by the induction of PttRGA which encodes a negative regulator of growth in the autumn and that of a GA-20 oxidase, a key gibberellin biosynthesis gene during reactivation in spring. In summary, our data reveal the dynamics of transcriptional and metabolic networks and identify potential targets of environmental and hormonal signals in the regulation of the activity,dormancy cycle in cambial meristem. [source] | ||||||||||