The interaction of the organizing regions in hydra and its possible relation to the role of the cut end in regeneration

Development ◽  
1974 ◽  
Vol 31 (3) ◽  
pp. 541-555 ◽  
Author(s):  
Stuart A. Newman
Keyword(s):  
Cell Division ◽  
Pattern Formation ◽  
Positional Information ◽  
Regenerative Process ◽  
Basal Disc ◽  
Model Based ◽  
Pattern Regulation ◽  
Cut Surface

Regeneration in hydra does not necessarily involve cell division, so that the problem of pattern regulation is essentially one of finding the processes by which a given population of cells are assigned appropriate functions in the correct positions. The restoration and nature of the organizers or ‘dominant regions’ must also be explained. Lateral transplants of the two different organizer tissues (hypostome and basal disc) into the digestive regions of host animals unexpectedly antagonize one another's inductive ability, suggesting that the heretofore separately studied distal and proximal developmental fields may in fact be interconnected. A model based on this idea, incorporating the extinction results with classical findings, leads to the hypothesis of a role for leakage from the cut surface as a trigger for the regenerative process. This is tested using a ligature technique in which the cut surface is minimized when the hypostome is removed, and the degree of regeneration is found to be significantly lowered, in agreement with prediction. These results are discussed in relation to ‘positional information’ and ‘special substance’ models for pattern formation.

Positional information and pattern regulation in Hydra. Dynamics of regions at the boundary

Development ◽  
1975 ◽  
Vol 33 (2) ◽  
pp. 499-510
Author(s):  
J. Hicklin ◽  
A. Hornbruch ◽  
L. Wolpert
Keyword(s):  
Positional Information ◽  
Boundary Region ◽  
The Times ◽  
Pattern Regulation ◽  
Cut Surface

The dynamics of boundary regions have been investigated mainly by axial grafting and with the emphasis on the head end. The time to lesist inhibition of head-end formation and the ability to inhibit head-end formation have been assayed under a variety of conditions. The times increase with distance from the head end. The times required by a boundary region to acquire the inhibitory properties of a head end are longer than those required to acquire resistance to inhibition. Determination of a head end is faster at a cut surface and at higher temperatures. The results are discussed in terms of a model involving two gradients. Some anomalous results are reported.

scholarly journals Positional information and pattern regulation in hydra: formation of the foot end

Development ◽  
1973 ◽  
Vol 30 (3) ◽  
pp. 727-740
Author(s):  
J. Hicklin ◽  
L. Wolpert
Keyword(s):  
Positional Information ◽  
Basal Disc ◽  
Time Required ◽  
Pattern Regulation

The time required for foot end formation increases with distance from the foot end. Using lateral grafting it was shown that both the peduncle and basal disc could induce a proximal axis when grafted into the gastric region. The time for foot end determination was shown to be about 4 h at the proximal end of the gastric region and to increase towards the head end. In general the determination of the foot end is similar to that of the head end.

Positional information and pattern regulation in hydra: the effect of γ-radiation

Development ◽  
1973 ◽  
Vol 30 (3) ◽  
pp. 741-752
Author(s):  
J. Hicklin ◽  
L. Wolpert
Keyword(s):  
Cell Division ◽  
Positional Information ◽  
Γ Irradiation ◽  
Γ Radiation ◽  
Head Formation ◽  
High Doses ◽  
Mitotic Figures ◽  
Pattern Regulation

Hydra exposed to high doses of γ-irradiation (25000 rad) are still capable of regeneration although no normal mitotic figures could be seen for up to 48 h after irradiation. Irradiated heads could still inhibit head formation in other regions in graft combinations. The time for head end determination in irradiated animals appeared to be increased. It is concluded that head end regeneration need not involve cell division.

scholarly journals Biological notion of positional information/value in morphogenesis theory

2020 ◽  
Vol 64 (10-11-12) ◽  
pp. 453-463
Author(s):  
Yue Wang ◽  
Jérémie Kropp ◽  
Nadya Morozova
Keyword(s):  
Pattern Formation ◽  
Molecular Mechanisms ◽  
Positional Information ◽  
Theoretical Models ◽  
Cell Development ◽  
Information Value ◽  
Morphogen Gradients ◽  
Cell Position ◽  
Positional Value

The notions of positional information and positional value describe the role of cell position in cell development and pattern formation. Despite their frequent usage in literature, their definitions are blurry, and are interpreted differently by different researchers. Through reflection on previous definitions and usage, and analysis of related experiments, we propose three clear and verifiable criteria for positional information/value. Then we reviewed literature on molecular mechanisms of cell development and pattern formation, to search for a possible molecular basis of positional information/value, including those used in theoretical models. We conclude that although morphogen gradients and cell-to-cell contacts are involved in the pattern formation process, complete molecular explanations of positional information/value are still far from reality.

Regeneration of surgically created mixed-handed axolotl forelimbs: pattern formation in the dorsal—ventral axis

Development ◽  
1984 ◽  
Vol 82 (1) ◽  
pp. 217-239
Author(s):  
Nigel Holder ◽  
Charleston Weekes
Keyword(s):  
Pattern Formation ◽  
Leydig Cell ◽  
Cell Number ◽  
Upper Arm ◽  
Posterior Limb ◽  
Almost All ◽  
Forearm Muscle ◽  
Pattern Regulation ◽  
Anterior Posterior

The regeneration of surgically created mixed-handed limb stumps is examined in the axolotl. Operations were performed in the lower arm and upper arm regions and grafts were allowed to heal for approximately one month prior to amputation or were amputated immediately. In the lower arm group both anterior and posterior limb halves were inverted, whereas only posterior halves were inverted in the upper arm group. Almost all the limbs regenerated were normal in the anterior-posterior axis, whereas a range of limb types were found when the dorsal-ventral axis was analysed usingthe metacarpal muscle pattern and epidermal Leydig cell number as positional markers. The carpal and forearm muscle patterns were also analysed in order to assess whether the pattern determined from analysis at the metacarpal level reflected that seen at more proximal levels. The results are discussed in terms of the possible role of cell contribution from the stump to the blastema andthe relevance of the study to models of pattern regulation.

scholarly journals The role of targeted secretion in the establishment of cell polarity and the orientation of the division plane in Fucus zygotes

Development ◽  
1996 ◽  
Vol 122 (9) ◽  
pp. 2623-2630 ◽  
Author(s):  
S.L. Shaw ◽  
R.S. Quatrano
Keyword(s):  
Cell Wall ◽  
Cell Division ◽  
Cell Polarity ◽  
Polar Axis ◽  
Positional Information ◽  
Target Site ◽  
Polar Growth ◽  
Division Plane ◽  
Axis Fixation

In this study, we investigate the role of polar secretion and the resulting asymmetry in the cell wall in establishing polarity in Fucus zygotes. We have utilized brefeldin-A to selectively interrupt secretion of Golgi-derived material into the cell wall as assayed by toluidine blue O staining of sulfated fucoidin. We show that the polar secretion of Golgi-derived material is targeted to a cortical site of the zygote identified by the localization of actin filaments and dihydropyridine receptors. The deposition of Golgi-derived material into the cell wall at this target site is temporally coincident with and required for polar axis fixation. We propose that local secretion of Golgi-derived material into the cell wall transforms the target site into the fixed site of polar growth. We also found that polar secretion of Golgi-derived material at the fixed site is essential for growth and differentiation of the rhizoid, as well as for the proper positioning of the first plane of cell division. We propose that the resulting asymmetry in the cell wall serves as positional information for the underlying cortex to initiate these polar events. Our data supports the hypothesis that cell wall factors in embryos, previously shown to be responsible for induction of rhizoid cell differentiation, are deposited simultaneously with and are responsible for polar axis fixation. Furthermore, the pattern of polar growth is attributable to a positional signal at the fixed site and appears to be independent of the orientation of the first cell division plane. Thus, the establishment of zygotic cell polarity and not the position of the first division plane, is critical for the formation of the initial embryonic pattern in Fucus.

scholarly journals F4/80+ Kupffer Cell-Derived Oncostatin M Sustains the Progression Phase of Liver Regeneration through Inhibition of TGF-β2 Pathway

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2231
Author(s):  
Qingjun Lu ◽  
Hao Shen ◽  
Han Yu ◽  
Jing Fu ◽  
Hui Dong ◽  
...  
Keyword(s):  
Liver Regeneration ◽  
Serum Levels ◽  
Inhibitory Effect ◽  
Regenerative Process ◽  
Oncostatin M ◽  
Hepatocyte Proliferation ◽  
Initiation Phase ◽  
Distinct Role

The role of Kupffer cells (KCs) in liver regeneration is complicated and controversial. To investigate the distinct role of F4/80+ KCs at the different stages of the regeneration process, two-thirds partial hepatectomy (PHx) was performed in mice to induce physiological liver regeneration. In pre- or post-PHx, the clearance of KCs by intraperitoneal injection of the anti-F4/80 antibody (α-F4/80) was performed to study the distinct role of F4/80+ KCs during the regenerative process. In RNA sequencing of isolated F4/80+ KCs, the initiation phase was compared with the progression phase. Immunohistochemistry and immunofluorescence staining of Ki67, HNF-4α, CD-31, and F4/80 and Western blot of the TGF-β2 pathway were performed. Depletion of F4/80+ KCs in pre-PHx delayed the peak of hepatocyte proliferation from 48 h to 120 h, whereas depletion in post-PHx unexpectedly led to persistent inhibition of hepatocyte proliferation, indicating the distinct role of F4/80+ KCs in the initiation and progression phases of liver regeneration. F4/80+ KC depletion in post-PHx could significantly increase TGF-β2 serum levels, while TGF-βRI partially rescued the impaired proliferation of hepatocytes. Additionally, F4/80+ KC depletion in post-PHx significantly lowered the expression of oncostatin M (OSM), a key downstream mediator of interleukin-6, which is required for hepatocyte proliferation during liver regeneration. In vivo, recombinant OSM (r-OSM) treatment alleviated the inhibitory effect of α-F4/80 on the regenerative progression. Collectively, F4/80+ KCs release OSM to inhibit TGF-β2 activation, sustaining hepatocyte proliferation by releasing a proliferative brake.

scholarly journals The Role of Trip Lengths Calibration in Model-Based Perimeter Control Strategies

2021 ◽  
pp. 1-11
Author(s):  
Sergio F. A. Batista ◽  
Deepak Ingole ◽  
Ludovic Leclercq ◽  
Monica Menendez
Keyword(s):  
Control Strategies ◽  
Model Based

scholarly journals Cardiac regeneration: epicardial mediated repair

2015 ◽  
Vol 282 (1821) ◽  
pp. 20152147 ◽  
Author(s):  
Teresa Kennedy-Lydon ◽  
Nadia Rosenthal
Keyword(s):  
Stem Cells ◽  
Endothelial Cells ◽  
Cardiac Fibroblasts ◽  
Cardiac Regeneration ◽  
Repair Process ◽  
Regenerative Process ◽  
Cardiac Stem Cell ◽  
Cardiomyocyte Proliferation ◽  
Lower Vertebrates

The hearts of lower vertebrates such as fish and salamanders display scarless regeneration following injury, although this feature is lost in adult mammals. The remarkable capacity of the neonatal mammalian heart to regenerate suggests that the underlying machinery required for the regenerative process is evolutionarily retained. Recent studies highlight the epicardial covering of the heart as an important source of the signalling factors required for the repair process. The developing epicardium is also a major source of cardiac fibroblasts, smooth muscle, endothelial cells and stem cells. Here, we examine animal models that are capable of scarless regeneration, the role of the epicardium as a source of cells, signalling mechanisms implicated in the regenerative process and how these mechanisms influence cardiomyocyte proliferation. We also discuss recent advances in cardiac stem cell research and potential therapeutic targets arising from these studies.

scholarly journals MexAB-OprM Efflux Pump Interaction with the Peptidoglycan of Escherichia coli and Pseudomonas aeruginosa

2021 ◽  
Vol 22 (10) ◽  
pp. 5328
Author(s):  
Miao Ma ◽  
Margaux Lustig ◽  
Michèle Salem ◽  
Dominique Mengin-Lecreulx ◽  
Gilles Phan ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Pseudomonas Aeruginosa ◽  
Cell Division ◽  
Membrane Proteins ◽  
Outer Membrane ◽  
Efflux Pump ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Active Efflux

One of the major families of membrane proteins found in prokaryote genome corresponds to the transporters. Among them, the resistance-nodulation-cell division (RND) transporters are highly studied, as being responsible for one of the most problematic mechanisms used by bacteria to resist to antibiotics, i.e., the active efflux of drugs. In Gram-negative bacteria, these proteins are inserted in the inner membrane and form a tripartite assembly with an outer membrane factor and a periplasmic linker in order to cross the two membranes to expulse molecules outside of the cell. A lot of information has been collected to understand the functional mechanism of these pumps, especially with AcrAB-TolC from Escherichia coli, but one missing piece from all the suggested models is the role of peptidoglycan in the assembly. Here, by pull-down experiments with purified peptidoglycans, we precise the MexAB-OprM interaction with the peptidoglycan from Escherichia coli and Pseudomonas aeruginosa, highlighting a role of the peptidoglycan in stabilizing the MexA-OprM complex and also differences between the two Gram-negative bacteria peptidoglycans.

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