Spatiotemporal Regulation of Ras-GTPases During Chemotaxis

2009 ◽  
pp. 333-348 ◽  
Author(s):  
Atsuo T. Sasaki ◽  
Richard A. Firtel
Keyword(s):  
Ras Gtpases ◽  
Spatiotemporal Regulation

scholarly journals Effects of circadian clock and light on melatonin concentration in Hypericum perforatum L. (St. John’s Wort)

2020 ◽  
Vol 61 (1) ◽  
Author(s):  
Ming-Hsiu Chung ◽  
Tzu-Shing Deng
Keyword(s):  
High Performance ◽  
Hypericum Perforatum ◽  
Fresh Weight ◽  
Melatonin Concentration ◽  
Long Day ◽  
Spatiotemporal Regulation ◽  
Circadian Time ◽  
Hypericum Perforatum L ◽  
Pharmaceutical Industries ◽  
Oriented Research

Abstract Background Melatonin acts as a signaling hormone and entraining agent in many organisms. We studied the spatiotemporal regulation and influence of light (photoperiods, intensities, and spectral qualities) on melatonin concentration in the medicinal herb Hypericum perforatum L. Furthermore, melatonin concentrations in the leaves of eight species of the Hypericum genus were compared and analyzed using high-performance liquid chromatography. Results Melatonin concentration was found to be the highest in its flowers and leaves. The leaves exhibited a rhythmic variation in melatonin concentration of approximately 24 h under both light–dark entrained (Zeitgeber time) and constant light [circadian time (CT)] conditions, with melatonin concentration peaking at approximately CT6 in the middle of the subjective day. Melatonin concentration was influenced significantly by not only photoperiods but also applied light’s wavelength and intensity. It was approximately six times higher under long-day conditions (18-h light:6-h dark) than under short-day photoperiods (10-h light:14-h dark) and was the highest (131 μg/g fresh weight [FW]) under treatment with blue light at an intensity of 45 µmol·m2/s of photons. The melatonin concentration of the two examined Hypericum spp., namely H. kouytchense Lev. and H. coris L., were approximately twice that of H. perforatum L. Conclusion Our findings provide first insights on melatonin-related functions and mechanisms in the circadian system of H. perforatum and useful resources for further melatonin-oriented research and possible applications in agriculture and pharmaceutical industries.

scholarly journals Cdc42 and formin activity control non-muscle myosin dynamics during Drosophila heart morphogenesis

2014 ◽  
Vol 206 (7) ◽  
pp. 909-922 ◽  
Author(s):  
Georg Vogler ◽  
Jiandong Liu ◽  
Timothy W. Iafe ◽  
Ede Migh ◽  
József Mihály ◽  
...  
Keyword(s):  
Cell Fate ◽  
Matrix Protein ◽  
Small Gtpase ◽  
Extracellular Matrix Protein ◽  
Specific Expression ◽  
Heart Morphogenesis ◽  
Lumen Formation ◽  
Spatiotemporal Regulation ◽  
Genetic Mechanisms ◽  
Heart Formation

During heart formation, a network of transcription factors and signaling pathways guide cardiac cell fate and differentiation, but the genetic mechanisms orchestrating heart assembly and lumen formation remain unclear. Here, we show that the small GTPase Cdc42 is essential for Drosophila melanogaster heart morphogenesis and lumen formation. Cdc42 genetically interacts with the cardiogenic transcription factor tinman; with dDAAM which belongs to the family of actin organizing formins; and with zipper, which encodes nonmuscle myosin II. Zipper is required for heart lumen formation, and its spatiotemporal activity at the prospective luminal surface is controlled by Cdc42. Heart-specific expression of activated Cdc42, or the regulatory formins dDAAM and Diaphanous caused mislocalization of Zipper and induced ectopic heart lumina, as characterized by luminal markers such as the extracellular matrix protein Slit. Placement of Slit at the lumen surface depends on Cdc42 and formin function. Thus, Cdc42 and formins play pivotal roles in heart lumen formation through the spatiotemporal regulation of the actomyosin network.

scholarly journals The signalling role of ROS in the regulation of seed germination and dormancy

2019 ◽  
Vol 476 (20) ◽  
pp. 3019-3032 ◽  
Author(s):  
Christophe Bailly
Keyword(s):  
Seed Germination ◽  
Oxygen Species ◽  
Direct Oxidation ◽  
Cellular Events ◽  
Seed Physiology ◽  
Spatiotemporal Regulation ◽  
Wide Range ◽  
Living Organisms ◽  
Hormone Signalling

Abstract Reactive oxygen species (ROS) are versatile compounds which can have toxic or signalling effects in a wide range living organisms, including seeds. They have been reported to play a pivotal role in the regulation of seed germination and dormancy but their mechanisms of action are still far from being fully understood. In this review, we sum-up the major findings that have been carried out this last decade in this field of research and which altogether shed a new light on the signalling roles of ROS in seed physiology. ROS participate in dormancy release during seed dry storage through the direct oxidation of a subset of biomolecules. During seed imbibition, the controlled generation of ROS is involved in the perception and transduction of environmental conditions that control germination. When these conditions are permissive for germination, ROS levels are maintained at a level which triggers cellular events associated with germination, such as hormone signalling. Here we propose that the spatiotemporal regulation of ROS production acts in concert with hormone signalling to regulate the cellular events involved in cell expansion associated with germination.

scholarly journals A silencer repressing redundant enhancer activities revealed by deleting endogenouscis-regulatory element ofebonyinDrosophila melanogaster

2021 ◽  
Author(s):  
Noriyoshi Akiyama ◽  
Shoma Sato ◽  
Kentaro M. Tanaka ◽  
Takaomi Sakai ◽  
Aya Takahashi
Keyword(s):  
Drosophila Melanogaster ◽  
Genome Editing ◽  
Expression Pattern ◽  
Regulatory Region ◽  
Regulatory Elements ◽  
Biosynthesis Pathway ◽  
Melanin Biosynthesis ◽  
Pigment Synthesis ◽  
Endogenous Expression ◽  
Spatiotemporal Regulation

AbstractThe spatiotemporal regulation of gene expression is essential to ensure robust phenotypic outcomes. Pigmentation patterns inDrosophilaare formed by the deposition of different pigments synthesized in the developing epidermis and the role ofcis-regulatory elements (CREs) of melanin biosynthesis pathway-related genes is well-characterized. These CREs typically exhibit modular arrangement in the regulatory region of the gene with each enhancer regulating a specific spatiotemporal expression of the gene. However, recent studies have suggested that multiple enhancers of a number of developmental genes as well as those ofyellow(involved in dark pigment synthesis) exhibit redundant activities. Here we report the redundant enhancer activities in thecis-regulatory region of another gene in the melanin biosynthesis pathway,ebony, in the developing epidermis ofDrosophila melanogaster. The evidence was obtained by introducing an approximately 1 kbp deletion at the endogenous primary epidermis enhancer (priEE) by genome editing. The effect of the priEE deletion on pigmentation and on the endogenous expression pattern of amCherry-taggedebonyallele was examined in the thoracic and abdominal segments. The expression level ofebonyin the priEE-deleted strains was similar to that of the control strain, indicating the presence of redundant enhancer activities that drive the broad expression ofebonyin the developing epidermis. Additionally, the priEE fragment contained a silencer that suppressesebonyexpression in the dorsal midline of the abdominal tergites, which is necessary for the development of the subgenusSophophora-specific dark pigmentation patterns along the midline. The endogenous expression pattern ofebonyin the priEE-deleted strains and the reporter assay examining the autonomous activity of the priEE fragment indicated that the silencer is involved in repressing the activities of both proximal and distant enhancers. These results suggest that multiple silencers are dispensable in the regulatory system of a relatively stable taxonomic character. The prevalence of other redundant enhancers and silencers in the genome can be investigated using a similar approach.Author summaryGenes are expressed at the right timing and place to give rise to diverse phenotypes. The spatiotemporal regulation is usually achieved through the coordinated activities of transcription-activating and transcription-repressing proteins that bind to the DNA sequences called enhancers and silencers, respectively, located near the target gene. Most studies identified the locations of enhancers by examining the ability of the sequence fragments to regulate the expression of fused reporters. Various short enhancers have been identified using this approach. This study employed an alternative approach in which the previously identified enhancer that regulates expression ofebony(a gene involved in body color formation) was deleted in a fruitfly,Drosophila melanogaster, using the genome-editing technique. The knockout of this enhancer did not affect the transcription level of the gene to a large extent. This indicated the presence of transcription-activating elements with redundant functions outside the deleted enhancer. Additionally, the transcription ofebonyat the midline of the abdomen, which is repressed in the normal flies, were derepressed in the enhancer-deleted flies, which indicated that the deleted enhancer fragment contained a silencer that negatively regulates multiple enhancer activities in a spatially restricted manner.

scholarly journals Reconstitution of immune cell interactions in free-standing membranes

2018 ◽  
Author(s):  
Edward Jenkins ◽  
Ana Mafalda Santos ◽  
James H. Felce ◽  
Deborah Hatherley ◽  
Michael L. Dustin ◽  
...  
Keyword(s):  
Synapse Formation ◽  
Immune Cell ◽  
Cell Interactions ◽  
Free Standing ◽  
Immune Synapse ◽  
Signalling Molecules ◽  
Transient Nature ◽  
Spatiotemporal Regulation ◽  
Summary Statement

AbstractThe spatiotemporal regulation of signalling proteins at the contacts formed between immune cells and their targets determines how and when immune responses begin and end. It is important, therefore, to be able to elucidate molecular processes occurring at these interfaces. However, the detailed investigation of each component’s contribution to the formation and regulation of the contact is hampered by the complexity of cellular composition and architecture. Moreover, the transient nature of these interactions creates additional challenges, especially for using advanced imaging technology. One approach to circumventing these problems is to establish in vitro systems that faithfully mimic immune cell interactions, incorporating complexity that can be ‘dialled-in’ as needed. Here, we present an in vitro system making use of synthetic vesicles that mimic important aspects of immune cell surfaces. Using this system, we begin to investigate the spatial distribution of signalling molecules (receptors, kinases and phosphatases) and the intracellular rearrangements that accompany the initiation of signalling in T cells. The model system presented here is expected to be widely applicable.Summary StatementImmune cell-cell interactions are reconstituted in free-standing vesicles wherein spatiotemporal aspects of immune synapse formation can be investigated.

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