scholarly journals An early cortical progenitor-specific mechanism regulates thalamocortical innervation

2021 ◽  
pp. JN-RM-0226-21
Author(s):  
Suranjana Pal ◽  
Deepanjali Dwivedi ◽  
Tuli Pramanik ◽  
Geeta Godbole ◽  
Takuji Iwasato ◽  
...  
Keyword(s):  
Specific Mechanism ◽  
Cortical Progenitor

scholarly journals An early cortical progenitor-specific mechanism regulates thalamocortical innervation

2020 ◽  
Author(s):  
Suranjana Pal ◽  
Deepanjali Dwivedi ◽  
Tuli Pramanik ◽  
Geeta Godbole ◽  
Takuji Iwasato ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Cortical Plate ◽  
Specific Mechanism ◽  
Sensory Afferents ◽  
Waiting Period ◽  
Electrophysiological Properties ◽  
Thalamocortical Axons ◽  
Subplate Neurons ◽  
Cortical Progenitor

AbstractThe cortical subplate is critical in regulating the entry of thalamocortical sensory afferents into the cortex. These afferents reach the subplate at embryonic day (E)15.5 in the mouse, but “wait” for several days, entering the cortical plate postnatally. We report that when transcription factor Lhx2 is lost in E11.5 cortical progenitors, which give rise to subplate neurons, thalamocortical afferents display premature, exuberant innervation of the E15.5 cortex. Embryonic mutant subplate neurons are correctly positioned below the cortical plate, but they display an altered transcriptome and immature electrophysiological properties during the waiting period. The sensory thalamus in these cortex-specific Lhx2 mutants displays atrophy, eventually leading to severe deficits in thalamocortical innervation. Strikingly, these phenotypes do not manifest if Lhx2 is lost in postmitotic subplate neurons. These results demonstrate a mechanism operating in subplate progenitors that has profound consequences on the growth of thalamocortical axons into the cortex.

A Matter of Perspective: How adults represent causal launching sequences

2020 ◽  
Author(s):  
Deon T. Benton ◽  
David H. Rakison
Keyword(s):  
Specific Mechanism ◽  
Associative Mechanism ◽  
Low Level ◽  
Domain Specific ◽  
The World ◽  
Modular Domain ◽  
Stimulus Features

The ability to reason about causal events in the world is fundamental to cognition. Despite the importance of this ability, little is known about how adults represent causal events, what structure or form those representations take, and what the mechanism is that underpins such representations. We report four experiments with adults that examine the perceptual basis on which adults represent four-object launching sequences (Experiments 1 and 2), whether adults representations reflect sensitivity to the causal, perceptual, or causal and perceptual relation among the objects that comprise such sequences (Experiment 3), and whether such representations extend beyond spatiotemporal contiguity to include other low-level stimulus features such as an object’s shape and color (Experiment 4). Based on these results of the four experiments, we argue that a domain-general associative mechanism, rather a modular, domain-specific, mechanism subserves adults’ representations of four-object launching sequences.

scholarly journals 1186. Cefazolin inoculum effect predicts reduced susceptibility to other antibiotics and patient outcomes in MSSA endovascular infections

2020 ◽  
Vol 7 (Supplement_1) ◽  
pp. S617-S617
Author(s):  
Dan Smelter ◽  
Sue McCrone ◽  
Warren Rose
Keyword(s):  
Infective Endocarditis ◽  
Mortality Rate ◽  
Patient Outcomes ◽  
Treatment Options ◽  
Fold Increase ◽  
Specific Mechanism ◽  
Research Support ◽  
High Burden ◽  
Low Toxicity ◽  
Inoculum Effect

Abstract Background MSSA Infective endocarditis (IE) is inherently a high-burden infection with up to a 30% mortality rate. Cefazolin is an appealing treatment option for IE with low toxicity and a favorable dosing scheme. However, cefazolin has been associated with treatment failure in IE, attributed to an inoculum effect. The specific mechanism underlying the cefazolin inoculum effect (CIE) remains undetermined, but CIE has been linked to both blaZ expression and agr dysfunction. This study aims to determine whether CIE is linked to reduced susceptibility to other antibiotics and worse outcomes regardless of therapy in MSSA endovascular infections. Methods Sixty-four MSSA strains were collected from patients with endovascular infections not treated with cefazolin. To determine CIE phenotype, strains were cultured and MICs assayed for cefazolin, nafcillin, and vancomycin at 107 CFU/mL for high-inocula (HI) and 105 CFU/mL for standard-inocula (SI). This study defined CIE as a ≥ 4-fold increase in MIC at HI compared to SI, with at least an MIC of 4 mg/L at HI. Nitrocefin disks identified blaZ expression, and beta lysin disks were used to determine hemolysin type and agr function. Patient outcomes of mortality and bacteremia duration were assessed across cohorts. Results Twenty-four strains exhibit a CIE (38%), with 10 strains having an MIC of ≥ 32mg/L at HI. Nafcillin and vancomycin also had an inoculum effect, uncoupled from the CIE and occurring at a lower frequency and amplitude at HI. Presence of CIE had a greater association with blaZ expression (71% vs 25%) than agr dysfunction (38% vs 20%). 50% (9/18) of CIE infections were cleared within 48 hours while 77% (20/26) of CIE-negative infections were cleared within 48 hours (P=0.106). However, presence of CIE was not associated with increased mortality (25% CIE-positive vs 35%; P=0.578) Conclusion Previous studies for CIE failed to enrich for isolates from endovascular sources, where inocula are known to be high. This study presents one of the largest endovascular source cohorts for CIE evaluation. It identifies that CIE prevalence (38%) is higher than reports from diverse infection sources (10-36%). CIE appears to predict bacteremia duration with other MSSA treatment options, suggesting mechanisms independent of blaZ and agr function for this phenomenon. Disclosures Warren Rose, PharmD, MPH, Merck (Grant/Research Support)Paratek (Grant/Research Support)

scholarly journals Hyperoside promotes pollen tube growth by regulating the depolymerization effect of actin-depolymerizing factor 1 on microfilaments in okra

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Biying Dong ◽  
Qing Yang ◽  
Zhihua Song ◽  
Lili Niu ◽  
Hongyan Cao ◽  
...  
Keyword(s):  
Pollen Tube ◽  
Pollen Tube Growth ◽  
Pollen Germination ◽  
Pollen Tubes ◽  
Tube Growth ◽  
Actin Depolymerizing Factor ◽  
Specific Mechanism ◽  
Promoting Effect ◽  
New Research

AbstractMature pollen germinates rapidly on the stigma, extending its pollen tube to deliver sperm cells to the ovule for fertilization. The success of this process is an important factor that limits output. The flavonoid content increased significantly during pollen germination and pollen tube growth, which suggests it may play an important role in these processes. However, the specific mechanism of this involvement has been little researched. Our previous research found that hyperoside can prolong the flowering period of Abelmoschus esculentus (okra), but its specific mechanism is still unclear. Therefore, in this study, we focused on the effect of hyperoside in regulating the actin-depolymerizing factor (ADF), which further affects the germination and growth of pollen. We found that hyperoside can prolong the effective pollination period of okra by 2–3-fold and promote the growth of pollen tubes in the style. Then, we used Nicotiana benthamiana cells as a research system and found that hyperoside accelerates the depolymerization of intercellular microfilaments. Hyperoside can promote pollen germination and pollen tube elongation in vitro. Moreover, AeADF1 was identified out of all AeADF genes as being highly expressed in pollen tubes in response to hyperoside. In addition, hyperoside promoted AeADF1-mediated microfilament dissipation according to microfilament severing experiments in vitro. In the pollen tube, the gene expression of AeADF1 was reduced to 1/5 by oligonucleotide transfection. The decrease in the expression level of AeADF1 partially reduced the promoting effect of hyperoside on pollen germination and pollen tube growth. This research provides new research directions for flavonoids in reproductive development.

scholarly journals Control of Vulval Competence and Centering in the Nematode Oscheius sp. 1 CEW1

Genetics ◽  
2003 ◽  
Vol 163 (1) ◽  
pp. 133-146 ◽  
Author(s):  
Sophie Louvet-Vallée ◽  
Irina Kolotuev ◽  
Benjamin Podbilewicz ◽  
Marie-Anne Félix
Keyword(s):  
Germ Line ◽  
Specific Mechanism ◽  
C Elegans ◽  
Group 4 ◽  
Cell Ablation ◽  
Group 3 ◽  
Group 2 ◽  
P Cells ◽  
Large Category ◽  
Group 1

Abstract To compare vulva development mechanisms in the nematode Oscheius sp. 1 to those known in Caenorhabditis elegans, we performed a genetic screen for vulva mutants in Oscheius sp. 1 CEW1. Here we present one large category of mutations that we call cov, which affect the specification of the Pn.p ventral epidermal cells along the antero-posterior axis. The Pn.p cells are numbered from 1 to 12 from anterior to posterior. In wild-type Oscheius sp. 1 CEW1, the P(4-8).p cells are competent to form the vulva and the progeny of P(5-7).p actually form the vulva, with the descendants of P6.p adopting a central vulval fate. Among the 17 mutations (defining 13 genes) that we characterize here, group 1 mutations completely or partially abolish P(4-8).p competence, and this correlates with early fusion of the Pn.p cells to the epidermal syncytium. In this group, we found a putative null mutation in the lin-39 HOM-C homolog, the associated phenotype of which could be weakly mimicked by injection of a morpholino against Osp1-lin-39 in the mother’s germ line. Using cell ablation in a partially penetrant competence mutant, we show that vulval competence is partially controlled by a gonadal signal. Most other mutants found in the screen display phenotypes unknown in C. elegans. Group 2 mutants show a partial penetrance of Pn.p competence loss and an abnormal centering of the vulva on P5.p, suggesting that these two processes are coregulated by the same pathway in Oscheius sp. 1. Group 3 mutants display an enlarged competence group that includes P3.p, thus demonstrating the existence of a specific mechanism inhibiting P3.p competence. Group 4 mutants display an abnormal centering of the vulval pattern on P7.p and suggest that a specific mechanism centers the vulval pattern on a single Pn.p cell.

scholarly journals The 16p11.2 Deletion Mouse Model of Autism Exhibits Altered Cortical Progenitor Proliferation and Brain Cytoarchitecture Linked to the ERK MAPK Pathway

2015 ◽  
Vol 35 (7) ◽  
pp. 3190-3200 ◽  
Author(s):  
J. Pucilowska ◽  
J. Vithayathil ◽  
E. J. Tavares ◽  
C. Kelly ◽  
J. C. Karlo ◽  
...  
Keyword(s):  
Mouse Model ◽  
Mapk Pathway ◽  
Erk Mapk ◽  
Cortical Progenitor

The role of exploratory mechanisms in evolution

1995 ◽  
Vol 349 (1329) ◽  
pp. 297-297
Keyword(s):  
Dynamic Instability ◽  
Specific Mechanism ◽  
Cellular Mechanisms ◽  
Selection Processes ◽  
Wide Range ◽  
Rapid Changes ◽  
Neuronal Processes ◽  
History Of ◽  
Variation And Selection

Many cellular mechanisms use a process of variation and selection to generate specific patterns. Among these, dynamic instability of microtubules has been shown to employ a specific mechanism to intentionally generate variation. In many systems the growth of neurons or neuronal processes is excessive, the final connections being established by stabilization of functional interactions. When changes in neuronal networks take place, such as in metamorphosis, use is made of the plasticity of neuronal connectivity. In the immune system, specific responses are generated by variation and selection. Processes that explore a wide range of conditions and a wide range of structures can be called exploratory processes. These are very robust and capable of responding to damage, variability in the environment and ontogenic changes in the organisms. Such robustness would be useful for adapting to changes that occur during phylogenetic changes as well. Given the extensive history of extinction and radiation in evolution, it may be supposed that these mechanisms have themselves been selected for their capacity to survive rapid changes in the organism and for their ability to generate cellular variation.

A compass without a map: tortuosity and orientation of eastern painted turtles (Chrysemys picta picta) released in unfamiliar territory

2006 ◽  
Vol 84 (8) ◽  
pp. 1129-1137 ◽  
Author(s):  
I.R. Caldwell ◽  
V.O. Nams
Keyword(s):  
Fractal Dimension ◽  
Random Walk ◽  
Spatial Scales ◽  
Chrysemys Picta ◽  
Reference Stimulus ◽  
Correlated Random Walk ◽  
Specific Mechanism ◽  
Minimal Time ◽  
Painted Turtles

Orientation mechanisms allow animals to spend minimal time in hostile areas while reaching needed resources. Identification of the specific mechanism used by an animal can be difficult, but examining an animal's path in familiar and unfamiliar areas can provide clues to the type of mechanism in use. Semiaquatic turtles are known to use a homing mechanism in familiar territory to locate their home lake while on land, but little is known about their ability to locate habitat in unfamiliar territory. We tested the tortuosity and orientation of 60 eastern painted turtles ( Chrysemys picta picta (Schneider, 1783)). We released turtles at 20 release points located at five distances and in two directions from two unfamiliar lakes. Turtle trails were quite straight (fractal dimension between 1.1 and 1.025) but were not oriented towards water from any distance (V-test; u < 0.72; P > 0.1). Turtles maintained their initially chosen direction but either could not detect water or were not motivated to reach it. Furthermore, paths were straighter at larger spatial scales than at smaller spatial scales, which could not have occurred if the turtles had been using a correlated random walk. Turtles must therefore be using a reference stimulus for navigation even in unfamiliar areas.

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