scholarly journals Genetic and biochemical analysis of the role of Egfr in the morphogenetic furrow of the developing Drosophila eye

Development ◽  
2005 ◽  
Vol 132 (21) ◽  
pp. 4697-4707 ◽  
Author(s):  
A. B. Rodrigues
Keyword(s):  
Biochemical Analysis ◽  
Morphogenetic Furrow ◽  
Drosophila Eye

Role of the morphogenetic furrow in establishing polarity in the Drosophila eye

Development ◽  
1995 ◽  
Vol 121 (12) ◽  
pp. 4085-4094 ◽  
Author(s):  
F. Chanut ◽  
U. Heberlein
Keyword(s):  
Ectopic Expression ◽  
Morphogenetic Furrow ◽  
Eye Disc ◽  
Drosophila Eye ◽  
Retinal Epithelium ◽  
Anteroposterior Polarity ◽  
Crystalline Array

The Drosophila retina is a crystalline array of 800 ommatidia whose organization and assembly suggest polarization of the retinal epithelium along anteroposterior and dorsoventral axes. The retina develops by a stepwise process following the posterior-to-anterior progression of the morphogenetic furrow across the eye disc. Ectopic expression of hedgehog or local removal of patched function generates ectopic furrows that can progress in any direction across the disc leaving in their wake differentiating fields of ectopic ommatidia. We have studied the effect of these ectopic furrows on the polarity of ommatidial assembly and rotation. We find that the anteroposterior asymmetry of ommatidial assembly parallels the progression of ectopic furrows, regardless of their direction. In addition, ommatidia developing behind ectopic furrows rotate coordinately, forming equators in various regions of the disc. Interestingly, the expression of a marker normally restricted to the equator is induced in ectopic ommatidial fields. Ectopic equators are stable as they persist to adulthood, where they can coexist with the normal equator. Our results suggest that ectopic furrows can impart polarity to the disc epithelium, regarding the direction of both assembly and rotation of ommatidia. We propose that these processes are polarized as a consequence of furrow propagation, while more global determinants of dorsoventral and anteroposterior polarity may act less directly by determining the site of furrow initiation.

Hedgehog is an indirect regulator of morphogenetic furrow progression in the Drosophila eye disc

Development ◽  
1997 ◽  
Vol 124 (17) ◽  
pp. 3233-3240 ◽  
Author(s):  
D.I. Strutt ◽  
M. Mlodzik
Keyword(s):  
Pattern Formation ◽  
Imaginal Disc ◽  
Morphogenetic Furrow ◽  
Anterior Edge ◽  
Eye Disc ◽  
Drosophila Eye ◽  
Eye Imaginal Disc ◽  
Inductive Signal ◽  
Rate Of Movement

Pattern formation in the eye imaginal disc of Drosophila occurs in a wave that moves from posterior to anterior. The anterior edge of this wave is marked by a contracted band of cells known as the morphogenetic furrow, behind which photoreceptors differentiate. The movement of the furrow is dependent upon the secretion of the signalling protein Hedgehog (Hh) by more posterior cells, and it has been suggested that Hh acts as an inductive signal to induce cells to enter a furrow fate and begin differentiation. To further define the role of Hh in this process, we have analysed clones of cells lacking the function of the smoothened (smo) gene, which is required for transduction of the Hh signal and allows the investigation of the autonomous requirement for hh signalling. These experiments demonstrate that the function of hh in furrow progression is indirect. Cells that cannot receive/transduce the Hh signal are still capable of entering a furrow fate and differentiating normally. However, hh is required to promote furrow progression and regulate its rate of movement across the disc, since the furrow is significantly delayed in smo clones.

The role of Wingless signaling in establishing the anteroposterior and dorsoventral axes of the eye disc

Development ◽  
2001 ◽  
Vol 128 (9) ◽  
pp. 1519-1529 ◽  
Author(s):  
J.D. Lee ◽  
J.E. Treisman
Keyword(s):  
Signaling Molecules ◽  
Morphogenetic Furrow ◽  
Wild Type ◽  
Dorsoventral Axis ◽  
Eye Disc ◽  
Wingless Signaling ◽  
Drosophila Eye ◽  
Ectopic Activation ◽  
Lateral Margins

The posteriorly expressed signaling molecules Hedgehog and Decapentaplegic drive photoreceptor differentiation in the Drosophila eye disc, while at the anterior lateral margins Wingless expression blocks ectopic differentiation. We show here that mutations in axin prevent photoreceptor differentiation and lead to tissue overgrowth and that both these effects are due to ectopic activation of the Wingless pathway. In addition, ectopic Wingless signaling causes posterior cells to take on an anterior identity, reorienting the direction of morphogenetic furrow progression in neighboring wild-type cells. We also show that signaling by Decapentaplegic and Hedgehog normally blocks the posterior expression of anterior markers such as Eyeless. Wingless signaling is not required to maintain anterior Eyeless expression and in combination with Decapentaplegic signaling can promote its downregulation, suggesting that additional molecules contribute to anterior identity. Along the dorsoventral axis of the eye disc, Wingless signaling is sufficient to promote dorsal expression of the Iroquois gene mirror, even in the absence of the upstream factor pannier. However, Wingless signaling does not lead to ventral mirror expression, implying the existence of ventral repressors.

scholarly journals Nitric oxide-dependent regulation of sweet pepper fruit ripening

2019 ◽  
Vol 70 (17) ◽  
pp. 4557-4570 ◽  
Author(s):  
Salvador González-Gordo ◽  
Rocío Bautista ◽  
M Gonzalo Claros ◽  
Amanda Cañas ◽  
José M Palma ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Fruit Ripening ◽  
Biochemical Analysis ◽  
Sweet Pepper ◽  
Supporting Evidence ◽  
Functional Categories ◽  
Fatty Acid Profiling ◽  
Pepper Fruit

Abstract Ripening is a complex physiological process that involves changes in reactive nitrogen and oxygen species that govern the shelf-life and quality of fruits. Nitric oxide (NO)-dependent changes in the sweet pepper fruit transcriptome were determined by treating fruits at the initial breaking point stage with NO gas. Fruits were also harvested at the immature (green) and ripe (red) stages. Fruit ripening in the absence of NO resulted in changes in the abundance of 8805 transcripts whose function could be identified. Among these, functional clusters associated with reactive oxygen/nitrogen species and lipid metabolism were significantly modified. NO treatment resulted in the differential expression of 498 genes framed within these functional categories. Biochemical analysis revealed that NO treatment resulted in changes in fatty acid profiling, glutathione and proline contents, and the extent of lipid peroxidation, as well as increases in the activity of ascorbate peroxidase and lipoxygenase. These data provide supporting evidence for the crucial role of NO in the ripening of pepper fruit.

scholarly journals Association of TM6SF2 rs58542926 with Hepatic and Extrahepatic Alterations in Chronic Hepatitis C Patients

2021 ◽  
Author(s):  
Mohi I. Mohammed Abdul ◽  
Adriana Vitiello ◽  
Hanieh Ghassabian ◽  
Heba M. Eltahir ◽  
Elham Ahmed Hassan ◽  
...  
Keyword(s):  
Chronic Hepatitis ◽  
Hepatitis C ◽  
Liver Fibrosis ◽  
Chronic Hepatitis C ◽  
Biochemical Analysis ◽  
Complete Blood Count ◽  
Minor Allele ◽  
Chronic Hepatitis C Patients ◽  
Severe Fibrosis

Abstract Human genetic variants play major roles in predicting and prognosis of several diseases. The effect of rs58542926 variant in transmembrane 6 superfamily member 2 (TM6SF2) gene on liver fibrosis among patients with chronic hepatitis C (CHC) is still debatable. The aim of this study is to investigate the possible effects of this variant in CHC patients. The study comprised 351 subjects: 250 CHC patients with different fibrosis stages (F0-F4) and 101 healthy volunteers. TM6SF2 (rs58542926) genotype was determined for all subjects. Blood samples were collected for complete blood count and biochemical analysis and cohort subjects were genotyped for the variant TM6SF2 rs58542926. Fibrosis staging was performed using Fibrotest and Fibroscan standard tests. The presence of the minor allele was significantly associated with severe liver fibrosis, as well as thrombocytopenia as an extrahepatic alteration. In addition, there was a significant association between the minor allele and lower thrombopoietin levels. The association of TM6SF2 genotype with thrombocytopenia was explored by measuring plasma thrombopoietin (TPO) levels for CHC patients. The results showed an association with extrahepatic alteration (thrombocytopenia) through its effect on plasma TPO level, and consequently on platelets production, which raises questions about the role of this variant in HCV treatment outcome. In conclusion, the occurrence of the minor allele of the variant rs58542926 can be linked to severe fibrosis stages as well as thrombocytopenia, enabling this variant to be used as a diagnostic pharmacogenetic marker for predicting the risk of fibrosis onset in CHC patients.

scholarly journals A disulfide constrains the ToxR periplasmic domain structure, altering its interactions with ToxS and bile-salts

2020 ◽  
Author(s):  
Charles R Midgett ◽  
Rachel A Swindell ◽  
Maria Pellegrini ◽  
F Jon Kull
Keyword(s):  
Crystal Structure ◽  
Transcription Factor ◽  
Disulfide Bond ◽  
Bile Salts ◽  
Biochemical Analysis ◽  
Conformation Analysis ◽  
Binding Partner ◽  
Bile Resistance ◽  
Periplasmic Domain

AbstractToxR is a transmembrane transcription factor that, together with its integral membrane periplasmic binding partner ToxS, is conserved across the Vibrio family. In some pathogenic Vibrios, including V. parahaemolyticus and V. cholerae, ToxR is required for bile resistance and virulence, and ToxR is fully activated and protected from degradation by ToxS. ToxS achieves this in part by ensuring formation of an intra-chain disulfide bond in the C-terminal periplasmic domain of ToxR (dbToxRp). In this study, biochemical analysis showed dbToxRp to have a higher affinity for the ToxS periplasmic domain than the non-disulfide bonded conformation. Analysis of our dbToxRp crystal structure showed this is due to disulfide bond stabilization. Furthermore, dbToxRp is structurally homologous to the V. parahaemolyticus VtrA periplasmic domain. These results highlight the critical structural role of disulfide bond in ToxR and along with VtrA define a domain fold involved in environmental sensing conserved across the Vibrio family.

Jun mediates Frizzled-induced R3/R4 cell fate distinction and planar polarity determination in the Drosophila eye

Development ◽  
2000 ◽  
Vol 127 (16) ◽  
pp. 3619-3629 ◽  
Author(s):  
U. Weber ◽  
N. Paricio ◽  
M. Mlodzik
Keyword(s):  
Cell Fate ◽  
Genetic Interaction ◽  
Function Analysis ◽  
Loss Of Function ◽  
Planar Polarity ◽  
Jnk Signaling ◽  
Drosophila Eye ◽  
Polarity Determination ◽  
Signaling Components

Jun acts as a signal-regulated transcription factor in many cellular decisions, ranging from stress response to proliferation control and cell fate induction. Genetic interaction studies have suggested that Jun and JNK signaling are involved in Frizzled (Fz)-mediated planar polarity generation in the Drosophila eye. However, simple loss-of-function analysis of JNK signaling components did not show comparable planar polarity defects. To address the role of Jun and JNK in Fz signaling, we have used a combination of loss- and gain-of-function studies. Like Fz, Jun affects the bias between the R3/R4 photoreceptor pair that is critical for ommatidial polarity establishment. Detailed analysis of jun(−) clones reveals defects in R3 induction and planar polarity determination, whereas gain of Jun function induces the R3 fate and associated polarity phenotypes. We find also that affecting the levels of JNK signaling by either reduction or overexpression leads to planar polarity defects. Similarly, hypomorphic allelic combinations and overexpression of the negative JNK regulator Puckered causes planar polarity eye phenotypes, establishing that JNK acts in planar polarity signaling. The observation that Dl transcription in the early R3/R4 precursor cells is deregulated by Jun or Hep/JNKK activation, reminiscent of the effects seen with Fz overexpression, suggests that Jun is one of the transcription factors that mediates the effects of fz in planar polarity generation.

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