BMPs mediate lateral inhibition at successive stages in feather tract development

Development ◽  
1998 ◽  
Vol 125 (19) ◽  
pp. 3775-3787 ◽  
Author(s):  
S. Noramly ◽  
B.A. Morgan
Keyword(s):  
Pattern Formation ◽  
Lateral Inhibition ◽  
Retroviral Vectors ◽  
Receptor Expression ◽  
Fgf Receptor ◽  
Inhibitory Signal ◽  
Size And Shape ◽  
Morphological Sign ◽  
Necessary And Sufficient ◽  
Do So

The spacing of feather buds in a tract is thought to arise from the interaction between an inducing signal from the dermis and an inhibitory signal generated in the nascent buds. Local BMP-2 expression in the ectoderm precedes the formation of the ectodermal placodes, which are the first morphological sign of bud differentiation. We have altered the activity of BMP-2 or BMP-4 in the ectoderm of the feather field by expressing them or their inhibitor noggin using retroviral vectors. These experiments demonstrate that BMP-2 is necessary and sufficient to mediate the lateral inhibition that positions buds in a tract. After buds are initiated, BMP-2 and BMP-4 continue to inhibit the adoption of bud fates and help to specify the size and shape of the bud. They may do so in part by their regulation of Fgf receptor expression in both the ectoderm and dermis. Additional insights into pattern formation in the feather bud can be inferred from the effects of altered BMP activity on bud morphogenesis.

scholarly journals Methamphetamine Administration Increases Proceptive Behavior by Activating Src Kinase and Upregulating Progesterone Receptor in the Medial Amygdala

2018 ◽  
Author(s):  
Katrina M Williams ◽  
Sarah A Rudzinskas ◽  
Jessica A Mong
Keyword(s):  
Progesterone Receptor ◽  
Phosphorylation Site ◽  
Progesterone Receptors ◽  
Receptor Expression ◽  
Medial Amygdala ◽  
Specific Manner ◽  
Receptor Action ◽  
Necessary And Sufficient ◽  
Motivated Behaviors

Methamphetamine, a psychostimulant drug of abuse, increases sexual motivation both in humans and in rodent models. The activation of dopamine type-1 receptors (D1Rs) within the medial amygdala, in the presence of ovarian hormones (EB+P), are both necessary and sufficient for increases in proceptive, or sexually motivated, behaviors. Here, we demonstrate that methamphetamine increases progesterone receptor expression in the medial amygdala independently of D1R activation, and that lentiviral overexpression of the progesterone receptor was able to recapitulate the methamphetamine-induced enhancement of proceptive behaviors. Furthermore, we found that within the medial amygdala, these progesterone receptors show an increase in phosphorylation of serine 294 of the progesterone receptor in a region-specific manner. The involvement of this phosphorylation site suggests a role for cytosolic kinases, which may be responsible for enhanced progesterone receptor action. The phosphorylation of serine 294 is blocked by D1R antagonists, and by inhibiting cSrc and ERK1/2, downstream of D1R signaling, we identified that Src and ERK1/2 are required for enhanced proceptive behavior. Taken together, we propose that within the medial amygdala, methamphetamine enhances progesterone receptors sensitivity to its cognate ligand via interaction with cSrc kinase and ERK1/2, as well as an increase total progesterone receptors, thus leading to enhanced proceptive behaviors in the rat.

Spots and stripes: the patterning spectrum in the cellular slime mould Polysphondylium pallidum

Development ◽  
1989 ◽  
Vol 105 (2) ◽  
pp. 323-333
Author(s):  
J.G. McNally ◽  
E.C. Cox
Keyword(s):  
Pattern Formation ◽  
Specific Antigen ◽  
Spherical Cell ◽  
The Novel ◽  
Cellular Slime Mould ◽  
Slime Mould ◽  
Size And Shape ◽  
Polysphondylium Pallidum ◽  
Cellular Slime ◽  
Pattern Determination

Whorls of the cellular slime mould Polysphondylium pallidum originate as spherical cell masses that during normal morphogenesis produce tips only at equidistant positions around their equator. We have observed a series of new patterns in whorls that differ from normal whorls only in that they are larger or more elongated. Among the novel patterns found were arrays of tips distributed fairly regularly over the whole whorl surface, as well as striped patterns detected at earlier stages with a tip-specific antigen. These altered patterns demonstrate that a whorl's size and shape are by themselves important factors in pattern determination. We have compared the range of observed patterns to those predicted by a variety of different theories. We find that while no one theory can account in detail for all of our observations, predictions based on Turing's scheme of pattern formation come the closest.

scholarly journals Persuasion: The Art of Changing Worldviews

2019 ◽  
Vol 109 (3) ◽  
pp. 996-1031 ◽  
Author(s):  
Simone Galperti
Keyword(s):  
World View ◽  
Sufficient Conditions ◽  
Bayesian Framework ◽  
Necessary And Sufficient Conditions ◽  
Trade Offs ◽  
Necessary And Sufficient ◽  
Disconfirming Evidence ◽  
Do So

Persuaders often face the task of changing their listeners’ world-view, which may involve conveying evidence that disconfirms that view. It has been shown, however, that people are often reluctant to change their worldviews. These aspects of persuasion cannot be captured in the standard Bayesian framework. The paper identifies the constraints, opportunities, and trade-offs of persuading people to change worldview. It finds necessary and sufficient conditions under which it is optimal for persuaders to do so. It also shows when and how they conceal disconfirming evidence and take advantage of their listener’s existing worldview. (JEL D82, D83, D91)

scholarly journals Rb, Rc and New Physics: An Updated Model Independent Analysis

1997 ◽  
Vol 12 (04) ◽  
pp. 723-742 ◽  
Author(s):  
P. Bamert
Keyword(s):  
Standard Model ◽  
Neutral Current ◽  
New Physics ◽  
Low Energy ◽  
Coupling Constant ◽  
A Value ◽  
Independent Analysis ◽  
The Standard Model ◽  
Necessary And Sufficient ◽  
Do So

We analyze LEP and SLC data from the 1995 Summer Conferences as well as from low energy neutral current experiments for signals of new physics. The reasons for doing this are twofold: first to explain the deviations from the Standard Model observed in Rb and Rc and second to constrain nonstandard contributions to couplings of the Z0 boson to all fermions and to the oblique parameters. We do so by comparing the data with the Standard Model as well as with a number of test hypotheses concerning the nature of the new physics. These include nonstandard [Formula: see text]-, [Formula: see text]- and [Formula: see text]-couplings as well as the couplings of the Z0 to fermions of the entire first, second and third generations and universal corrections to all up- and down-type quark couplings (as can arise see for example in Z' mixing models). We find that nonstandard [Formula: see text] couplings are both necessary and sufficient to explain the data and in particular the Rb anomaly. It is not possible to explain Rb, Rc and a value of the strong coupling constant consistent with low energy determinations invoking only nonstandard [Formula: see text]- and [Formula: see text]-couplings. To do so one has to have also new physics contributions to the [Formula: see text] or universal corrections to all [Formula: see text] couplings.

The Minimal Local-Asperity Hypothesis of Early Retinal Lateral Inhibition

2000 ◽  
Vol 12 (7) ◽  
pp. 1485-1517 ◽  
Author(s):  
Rosario M. Balboa ◽  
Norberto M. Grzywacz
Keyword(s):  
Information Theory ◽  
Lateral Inhibition ◽  
Horizontal Cells ◽  
Natural Images ◽  
Local Contrast ◽  
Spatial Profile ◽  
Probabilistic Knowledge ◽  
Attribute Extraction ◽  
Extraction Error ◽  
Do So

Recently we found that the theories related to information theory existent in the literature cannot explain the behavior of the extent of the lateral inhibition mediated by retinal horizontal cells as a function of background light intensity. These theories can explain the fall of the extent from intermediate to high intensities, but not its rise from dim to intermediate intensities. We propose an alternate hypothesis that accounts for the extent's bell-shape behavior. This hypothesis proposes that the lateral-inhibition adaptation in the early retina is part of a system to extract several image attributes, such as occlusion borders and contrast. To do so, this system would use prior probabilistic knowledge about the biological processing and relevant statistics in natural images. A key novel statistic used here is the probability of the presence of an occlusion border as a function of local contrast. Using this probabilistic knowledge, the retina would optimize the spatial profile of lateral inhibition to minimize attribute-extraction error. The two significant errors that this minimization process must reduce are due to the quantal noise in photoreceptors and the straddling of occlusion borders by lateral inhibition.

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