scholarly journals Stable establishment of organ polarity several plastochrons before primordium outgrowth in Arabidopsis

Development ◽  
2021 ◽  
Author(s):  
Feng Zhao ◽  
Jan Traas
Keyword(s):  
Early Development ◽  
Leaf Blade ◽  
Local Information ◽  
Dorsoventral Patterning ◽  
Subsequent Growth ◽  
Founder Cells ◽  
Shoot Meristems

In many species, leaves are initiated at the flanks of shoot meristems. Usually, subsequent growth mainly occurs in the plane of the leaf blade, which leads to the formation of a bifacial leaf with dorso-ventral identities. In a classical set of surgical experiments in potato meristems, Sussex provided evidence that dorsoventrality depends on a signal emanating from the meristem centre. Although these results could be reproduced in tomato, this concept has been debated. We revisited these experiments in Arabidopsis where a range of markers are available to target the precise site of ablation. Using specific markers for organ founder cells and dorsoventral identity, we were unable to perturb the polarity of leaves and sepals long before organ outgrowth. While results in Solanaceae suggested that dorsoventral patterning was unstable during early development, we find that in Arabidopsis the local information contained within and around the primordium is able to withstand major invasive perturbations, long before polarity is fully established.

The genetic control of the distinction between fat body and gonadal mesoderm in Drosophila

Development ◽  
1998 ◽  
Vol 125 (4) ◽  
pp. 713-723 ◽  
Author(s):  
V. Riechmann ◽  
K.P. Rehorn ◽  
R. Reuter ◽  
M. Leptin
Keyword(s):  
Genetic Control ◽  
Early Development ◽  
Fat Body ◽  
Homeotic Gene ◽  
Dorsoventral Patterning ◽  
Genetic Pathways ◽  
The Third ◽  
Body Development ◽  
Visceral Muscles ◽  
Somatic Muscles

The somatic muscles, the heart, the fat body, the somatic part of the gonad and most of the visceral muscles are derived from a series of segmentally repeated primordia in the Drosophila mesoderm. This work describes the early development of the fat body and its relationship to the gonadal mesoderm, as well as the genetic control of the development of these tissues. Segmentation and dorsoventral patterning genes define three regions in each parasegment in which fat body precursors can develop. Fat body progenitors in these regions are specified by different genetic pathways. Two regions require engrailed and hedgehog for their development while the third is controlled by wingless. decapentaplegic and one or more unknown genes determine the dorsoventral extent of these regions. In each of parasegments 10–12 one of these regions generates somatic gonadal precursors instead of fat body. The balance between fat body and somatic gonadal fate in these serially homologous cell clusters is controlled by at least five genes. We suggest a model in which tinman, engrailed and wingless are necessary to permit somatic gonadal develoment, while serpent counteracts the effects of these genes and promotes fat body development. The homeotic gene abdominalA limits the region of serpent activity by interfering in a mutually repressive feed back loop between gonadal and fat body development.

The rotated-lamina syndrome. VIII. Lamina rotation and anisophylly in two species of Elatostema (Urticacae), and early development of seedlings of E. sessile

Botany ◽  
2008 ◽  
Vol 86 (12) ◽  
pp. 1474-1487
Author(s):  
W. A. Charlton
Keyword(s):  
Early Development ◽  
Shoot Apex ◽  
Leaf Blade ◽  
Ventral Side ◽  
Small Scale ◽  
Basal Region ◽  
Initial State ◽  
Taxonomic Groups ◽  
The Way

Elatostema rugosum A. Cunn. and Elatostema sessile J.R. Forst. & G. Forst. have dorsiventral shoots in which the leaves are arranged in anisophyllous pairs forming four ranks: two on the dorsal and two on the ventral side of the shoot. The ventral leaves have expanded asymmetrical leaf blades with lamina rotation, i.e., the lamina develops in the bud facing towards the upper side of the shoot rather than towards the shoot apex. Each ventral leaf has an asymmetrical intrapetiolar stipule. Lamina rotation occurs by asymmetrical development at the base of the leaf blade above the attachment of the stipule. The dorsal leaves are small, scale-like, approximately symmetrical exstipulate structures. The development of the ventral leaf is generally similar to that found in previous studies of related anisophyllous cases, but the dorsal leaf is reduced to a scale and is simpler than in related cases. Seedlings of E. sessile have been examined to investigate the way in which the combination of unusual features of shoot structure is produced, and also to cast light on the homology of the dorsal leaf. Anisophylly and asymmetry appear in the first pair of leaves formed above the cotyledons in seedlings and become accentuated in subsequent pairs. Events in seedlings suggest the dorsal leaf is derived by reduction from an initial state with blade, stipule, and basal region to the basal region alone. The rapid establishment of lamina rotation and asymmetry in the seedling shoot differs from most other cases described and adds to previous arguments that lamina rotation has arisen independently in a number of taxonomic groups.

Individual differences, social attention, and the history of the social motivation hypotheses of autism

2019 ◽  
Vol 42 ◽  
Author(s):  
Peter C. Mundy
Keyword(s):  
Individual Differences ◽  
Early Development ◽  
Emotional Development ◽  
Social Motivation ◽  
Social Attention ◽  
Social Emotional Development ◽  
Social Emotional ◽  
Precise Understanding ◽  
The Social ◽  
History Of

Abstract The stereotype of people with autism as unresponsive or uninterested in other people was prominent in the 1980s. However, this view of autism has steadily given way to recognition of important individual differences in the social-emotional development of affected people and a more precise understanding of the possible role social motivation has in their early development.

Classical social reward signatures in infants with later ASD

2019 ◽  
Vol 42 ◽  
Author(s):  
Teodora Gliga ◽  
Mayada Elsabbagh
Keyword(s):  
Early Development ◽  
Social Motivation ◽  
Self Report ◽  
Social Reward ◽  
Socially Motivated

Abstract Autistic individuals can be socially motivated. We disagree with the idea that self-report is sufficient to understand their social drive. Instead, we underscore evidence for typical non-verbal signatures of social reward during the early development of autistic individuals. Instead of focusing on whether or not social motivation is typical, research should investigate the factors that modulate social drives.

Early Development of Drug-Induced Hepatic Necrosis

1971 ◽  
Vol 29 ◽  
pp. 576-577
Author(s):  
F. G. Zaki ◽  
E. Detzi ◽  
C. H. Keysser
Keyword(s):  
Early Development ◽  
Hepatic Necrosis ◽  
Screening Tests ◽  
Dense Matrix ◽  
Sprague Dawley ◽  
Electron Microscopic ◽  
Drug Induced ◽  
Hepatocellular Damage ◽  
Sprague Dawley Rats ◽  
Microscopic Studies

This study represents the first in a series of investigations carried out to elucidate the mechanism(s) of early hepatocellular damage induced by drugs and other related compounds. During screening tests of CNS-active compounds in rats, it has been found that daily oral administration of one of these compounds at a dose level of 40 mg. per kg. of body weight induced diffuse massive hepatic necrosis within 7 weeks in Charles River Sprague Dawley rats of both sexes. Partial hepatectomy enhanced the development of this peculiar type of necrosis (3 weeks instead of 7) while treatment with phenobarbital prior to the administration of the drug delayed the appearance of necrosis but did not reduce its severity.Electron microscopic studies revealed that early development of this liver injury (2 days after the administration of the drug) appeared in the form of small dark osmiophilic vesicles located around the bile canaliculi of all hepatocytes (Fig. 1). These structures differed from the regular microbodies or the pericanalicular multivesicular bodies. They first appeared regularly rounded with electron dense matrix bound with a single membrane. After one week on the drug, these vesicles appeared vacuolated and resembled autophagosomes which soon developed whorls of concentric lamellae or cisterns characteristic of lysosomes (Fig. 2). These lysosomes were found, later on, scattered all over the hepatocytes.

The early development of antenna and antennal sensilla in the noctuid moth, Agrotis segetum (Insecta: Lepidoptera)

1990 ◽  
Vol 48 (3) ◽  
pp. 502-503
Author(s):  
Eric Hallberg ◽  
Lina Hansén
Keyword(s):  
Cell Death ◽  
Stem Cell ◽  
Early Development ◽  
Larval Stage ◽  
Pupal Stage ◽  
Agrotis Segetum ◽  
Antennal Sensilla ◽  
Noctuid Moth ◽  
Standard Procedures

The antennal rudiments in lepidopterous insects are present as disks during the larval stage. The tubular double-walled antennal disk is present beneath the larval antenna, and its inner layer gives rise to the adult antenna during the pupal stage. The sensilla develop from a cluster of cells that are derived from one stem cell, which gives rise to both sensory and enveloping cells. During the morphogenesis of the sensillum these cells undergo major transformations, including cell death. In the moth Agrotis segetum the pupal stage lasts about 14 days (temperature, 25°C). The antennae, clearly seen from the exterior, were dissected and fixed according to standard procedures (3 % glutaraldehyde in 0.15 M cacaodylate buffer, followed by 1 % osmiumtetroxide in the same buffer). Pupae from day 1 to day 8, of both sexes were studied.

Live Confocal Analysis of Fertilization and Early Development

2001 ◽  
Vol 7 (S2) ◽  
pp. 1012-1013
Author(s):  
Uyen Tram ◽  
William Sullivan
Keyword(s):  
Drosophila Melanogaster ◽  
Embryonic Development ◽  
Real Time ◽  
Early Development ◽  
Fluorescent Probes ◽  
Primary Defect ◽  
Fluorescent Analysis ◽  
Dynamic Event ◽  
Enormous Amount ◽  
Fluorescent Studies

Embryonic development is a dynamic event and is best studied in live animals in real time. Much of our knowledge of the early events of embryogenesis, however, comes from immunofluourescent analysis of fixed embryos. While these studies provide an enormous amount of information about the organization of different structures during development, they can give only a static glimpse of a very dynamic event. More recently real-time fluorescent studies of living embryos have become much more routine and have given new insights to how different structures and organelles (chromosomes, centrosomes, cytoskeleton, etc.) are coordinately regulated. This is in large part due to the development of commercially available fluorescent probes, GFP technology, and newly developed sensitive fluorescent microscopes. For example, live confocal fluorescent analysis proved essential in determining the primary defect in mutations that disrupt early nuclear divisions in Drosophila melanogaster. For organisms in which GPF transgenics is not available, fluorescent probes that label DNA, microtubules, and actin are available for microinjection.

Do You Want to See the Tree? Ignore the Forest

2014 ◽  
Vol 61 (3) ◽  
pp. 205-214 ◽  
Author(s):  
Nicolas Poirel ◽  
Claire Sara Krakowski ◽  
Sabrina Sayah ◽  
Arlette Pineau ◽  
Olivier Houdé ◽  
...  
Keyword(s):  
Visual Recognition ◽  
Local Level ◽  
Local Information ◽  
Visual Environment ◽  
Global Information ◽  
Focus Attention ◽  
Global Level ◽  
Hierarchical Stimuli ◽  
Priming Paradigm ◽  
The One

The visual environment consists of global structures (e.g., a forest) made up of local parts (e.g., trees). When compound stimuli are presented (e.g., large global letters composed of arrangements of small local letters), the global unattended information slows responses to local targets. Using a negative priming paradigm, we investigated whether inhibition is required to process hierarchical stimuli when information at the local level is in conflict with the one at the global level. The results show that when local and global information is in conflict, global information must be inhibited to process local information, but that the reverse is not true. This finding has potential direct implications for brain models of visual recognition, by suggesting that when local information is conflicting with global information, inhibitory control reduces feedback activity from global information (e.g., inhibits the forest) which allows the visual system to process local information (e.g., to focus attention on a particular tree).

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