scholarly journals Drosophila larval epidermal cells only exhibit epidermal aging when they persist to the adult stage

2021 ◽  
Author(s):  
Yan Wang ◽  
Sirisha Burra ◽  
Michael J. Galko
Keyword(s):  
Cell Membranes ◽  
Adult Stage ◽  
Body Plan ◽  
Epidermal Cells ◽  
Lineage Tracing ◽  
The Body ◽  
Multinucleate Cells ◽  
Aging Program ◽  
Complete Transformation ◽  
Adult Cells

Holometabolous insects undergo a complete transformation of the body plan from the larval to the adult stage. In Drosophila, this transformation includes replacement of larval epidermal cells (LECs) by adult epidermal cells (AECs). AECs in Drosophila undergo a rapid and stereotyped aging program where they lose both cell membranes and nuclei. Whether LECs are capable of undergoing aging in a manner similar to AECs remains unknown. Here, we address this question in two ways. First, we looked for hallmarks of epidermal aging in larvae that have a greatly extended third instar and/or carry mutations that would cause premature epidermal aging at the adult stage. Such larvae, irrespective of genotype, did not show any of the signs of epidermal aging observed in the adult. Second, we developed a procedure to effect a heterochronic persistence of LECs into the adult epidermal sheet. Lineage tracing verified that presumptive LECs in the adult epidermis are not derived from imaginal epidermal histoblasts. LECs embedded within the adult epidermal sheet undergo clear signs of epidermal aging; they form multinucleate cells with each other and with the surrounding AECs. The incidence of adult cells with mixed AEC nuclei (small) and persistent LEC nuclei (large) increased with age. Our data reveals that epidermal aging in holometabolous Drosophila is a stage-specific phenomenon and that the capacity of LECs to respond to aging signals does exist.

scholarly journals Drosophila larval epidermal cells only exhibit epidermal aging when they persist to the adult stage

2020 ◽  
Author(s):  
Yan Wang ◽  
Sirisha Burra ◽  
Michael J. Galko
Keyword(s):  
Larval Stage ◽  
Cell Membranes ◽  
Adult Stage ◽  
Body Plan ◽  
Epidermal Cells ◽  
The Body ◽  
Multinucleate Cells ◽  
Aging Program ◽  
Summary Statement ◽  
Complete Transformation

AbstractHolometabolous insects undergo a complete transformation of the body plan from the larval to the adult stage. In Drosophila, this transformation includes replacement of larval epidermal cells (LECs) by adult epidermal cells (AECs). AECs in Drosophila undergo a rapid and stereotyped aging program where they lose both cell membranes and nuclei. Whether LEC’s are capable of undergoing aging in a manner similar to AECs remains unknown. Here, we address this question in two ways. First, we looked for hallmarks of epidermal aging in larvae that have a greatly extended third instar and/or carry mutations that would cause premature epidermal aging at the adult stage. Such larvae, irrespective of genotype, did not show any of the signs of epidermal aging observed in the adult. Second, we developed a procedure to effect a heterochronic persistence of LECs into the adult epidermal sheet. LECs embedded within the adult epidermal sheet undergo clear signs of epidermal aging; they form multinucleate cells with each other and with the surrounding AECs on the same schedule as the AECs themselves. Our data reveals that epidermal aging in holometabolous Drosophila is a stage-specific phenomenon and that the capacity of LECs to respond to aging signals does exist.Summary StatementWe show that Drosophila larval epidermal cells do not age at the larval stage. They do, however, exhibit signs of aging if they persist into the adult.

scholarly journals Expression patterns of signalling molecules and transcription factors in the early rabbit embryo and their significance for modelling amniote axis formation

2021 ◽  
Author(s):  
Ruben Plöger ◽  
Christoph Viebahn
Keyword(s):  
Transcription Factors ◽  
Expression Patterns ◽  
In Situ Hybridisation ◽  
Body Plan ◽  
The Body ◽  
Anchor Point ◽  
Axis Formation ◽  
Point Model ◽  
Signalling Molecules ◽  
Rabbit Embryo

AbstractThe anterior-posterior axis is a central element of the body plan and, during amniote gastrulation, forms through several transient domains with specific morphogenetic activities. In the chick, experimentally proven activity of signalling molecules and transcription factors lead to the concept of a ‘global positioning system’ for initial axis formation whereas in the (mammotypical) rabbit embryo, a series of morphological or molecular domains are part of a putative ‘three-anchor-point model’. Because circular expression patterns of genes involved in axis formation exist in both amniote groups prior to, and during, gastrulation and may thus be suited to reconcile these models, the expression patterns of selected genes known in the chick, namely the ones coding for the transcription factors eomes and tbx6, the signalling molecule wnt3 and the wnt inhibitor pkdcc, were analysed in the rabbit embryonic disc using in situ hybridisation and placing emphasis on their germ layer location. Peripheral wnt3 and eomes expression in all layers is found initially to be complementary to central pkdcc expression in the hypoblast during early axis formation. Pkdcc then appears — together with a posterior-anterior gradient in wnt3 and eomes domains — in the epiblast posteriorly before the emerging primitive streak is marked by pkdcc and tbx6 at its anterior and posterior extremities, respectively. Conserved circular expression patterns deduced from some of this data may point to shared mechanisms in amniote axis formation while the reshaping of localised gene expression patterns is discussed as part of the ‘three-anchor-point model’ for establishing the mammalian body plan.

scholarly journals Petiole-Lamina Transition Zone: A Functionally Crucial but Often Overlooked Leaf Trait

Plants ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 774
Author(s):  
Max Langer ◽  
Thomas Speck ◽  
Olga Speck
Keyword(s):  
Transition Zone ◽  
Three Dimensional ◽  
Spatial Arrangement ◽  
Body Plan ◽  
The Body ◽  
Vascular Bundles ◽  
Cross Sectional ◽  
Thin Sections ◽  
Transition Zones ◽  
The Cross

Although both the petiole and lamina of foliage leaves have been thoroughly studied, the transition zone between them has often been overlooked. We aimed to identify objectively measurable morphological and anatomical criteria for a generally valid definition of the petiole–lamina transition zone by comparing foliage leaves with various body plans (monocotyledons vs. dicotyledons) and spatial arrangements of petiole and lamina (two-dimensional vs. three-dimensional configurations). Cross-sectional geometry and tissue arrangement of petioles and transition zones were investigated via serial thin-sections and µCT. The changes in the cross-sectional geometries from the petiole to the transition zone and the course of the vascular bundles in the transition zone apparently depend on the spatial arrangement, while the arrangement of the vascular bundles in the petioles depends on the body plan. We found an exponential acropetal increase in the cross-sectional area and axial and polar second moments of area to be the defining characteristic of all transition zones studied, regardless of body plan or spatial arrangement. In conclusion, a variety of terms is used in the literature for describing the region between petiole and lamina. We prefer the term “petiole–lamina transition zone” to underline its three-dimensional nature and the integration of multiple gradients of geometry, shape, and size.

scholarly journals Scalable co-optimization of morphology and control in embodied machines

2018 ◽  
Vol 15 (143) ◽  
pp. 20170937 ◽  
Author(s):  
Nick Cheney ◽  
Josh Bongard ◽  
Vytas SunSpiral ◽  
Hod Lipson
Keyword(s):  
Embodied Cognition ◽  
Initial Conditions ◽  
Control Policy ◽  
Sensorimotor Control ◽  
Body Plan ◽  
The Body ◽  
Test Bed ◽  
Local Optima ◽  
Close Coupling ◽  
And Control

Evolution sculpts both the body plans and nervous systems of agents together over time. By contrast, in artificial intelligence and robotics, a robot's body plan is usually designed by hand, and control policies are then optimized for that fixed design. The task of simultaneously co-optimizing the morphology and controller of an embodied robot has remained a challenge. In psychology, the theory of embodied cognition posits that behaviour arises from a close coupling between body plan and sensorimotor control, which suggests why co-optimizing these two subsystems is so difficult: most evolutionary changes to morphology tend to adversely impact sensorimotor control, leading to an overall decrease in behavioural performance. Here, we further examine this hypothesis and demonstrate a technique for ‘morphological innovation protection’, which temporarily reduces selection pressure on recently morphologically changed individuals, thus enabling evolution some time to ‘readapt’ to the new morphology with subsequent control policy mutations. We show the potential for this method to avoid local optima and converge to similar highly fit morphologies across widely varying initial conditions, while sustaining fitness improvements further into optimization. While this technique is admittedly only the first of many steps that must be taken to achieve scalable optimization of embodied machines, we hope that theoretical insight into the cause of evolutionary stagnation in current methods will help to enable the automation of robot design and behavioural training—while simultaneously providing a test bed to investigate the theory of embodied cognition.

Growth, development and allometry of Philophthalmus nocturnus in the eyes of domestic chicks

1992 ◽  
Vol 66 (2) ◽  
pp. 100-107 ◽  
Author(s):  
V. G. M. Swarnakumari ◽  
R. Madhavi
Keyword(s):  
Growth Rate ◽  
Developmental Stages ◽  
Adult Stage ◽  
The Body ◽  
Lag Phase ◽  
Allometric Growth ◽  
Body Width ◽  
Rapid Phase ◽  
Growth Development ◽  
Two Phases

ABSTRACTFifty day-old chicks were each infected with 10 excysted metaccreariae of Philophthalimus nocturnus Looss. 1907 around each orbit and growth, development and allometry were studied. The growth rate showed two phases over a period of 35 days, a limited lag phase lasting two days post-infection in which flukes did not exceed 440 μm in length, and a rapid phase during which growth was rapid and flukes reached a size of 3·008–3·504 mm on day 35. Five developmental stages were noticed during the course of development of the metacercaria to the egg-producing adult stage. Eggs appeared in the uterus on day 14 and oculate miracidia on day 25. The hindhody, testes and ovary showed positive allometric growth, the pharnyx less so, whereas negative allometric growth was shown by the forebody. Body width, oral sucker and ventral sucker were close to isometry, growing at the same rate as the body length.

scholarly journals Cell-state transitions and collective cell movement generate an endoderm-like region in gastruloids

2020 ◽  
Author(s):  
Ali Hashmi ◽  
Sham Tlili ◽  
Pierre Perrin ◽  
Alfonso Martinez-Arias ◽  
Pierre-François Lenne
Keyword(s):  
Spatial Organization ◽  
Embryonic Stem ◽  
Cell Movement ◽  
Body Plan ◽  
The Body ◽  
State Transitions ◽  
Sequence Of Events ◽  
Complex Process ◽  
Cell Layers ◽  
Sorting Process

AbstractShaping the animal body plan is a complex process that involves the spatial organization and patterning of different cell layers. Recent advances in live imaging have started to unravel the cellular choreography underlying this process in mammals, however, the sequence of events transforming an unpatterned cell ensemble into structured territories is largely unknown. Here, using 3D aggregates of mouse embryonic stem cells, we study the formation of one of the three germ layers, the endoderm. We show that the endoderm is generated from an epiblast-like state by a three-step mechanism: a release of islands of Ecadherin expressing cells, their flow toward the aggregate tip, and their segregation. Unlike the prevailing view, this mechanism does not require epithelial-to-mesenchymal transitions and vice-versa but rather a fragmentation, which is mediated by Wnt/β-catenin, and a sorting process. Our data emphasize the role of signaling and cell flows in the establishment of the body plan.

scholarly journals A Novel Body Plan Alters Diversification of Body Shape and Genitalia in Live-Bearing Fish

2021 ◽  
Vol 9 ◽  
Author(s):  
R. Brian Langerhans ◽  
Eduardo Rosa-Molinar
Keyword(s):  
Complex Traits ◽  
Body Shape ◽  
Body Plan ◽  
The Body ◽  
Sperm Transfer ◽  
Body Region ◽  
Adaptive Divergence ◽  
Male Body ◽  
Correlated Evolution ◽  
Anterior Transposition

Major evolutionary innovations can greatly influence subsequent evolution. While many major transitions occurred in the deep past, male live-bearing fishes (family Poeciliidae) more recently evolved a novel body plan. This group possesses a three-region axial skeleton, with one region—the ano-urogenital region—representing a unique body region accommodating male genitalic structures (gonopodial complex). Here we evaluate several hypotheses for the evolution of diversity in this region and examine its role in the evolution of male body shape. Examining Gambusia fishes, we tested a priori predictions for (1) joint influence of gonopodial-complex traits on mating performance, (2) correlated evolution of gonopodial-complex traits at macro- and microevolutionary scales, and (3) predator-driven evolution of gonopodial-complex traits in a post-Pleistocene radiation of Bahamas mosquitofish. We found the length of the sperm-transfer organ (gonopodium) and its placement along the body (gonopodial anterior transposition) jointly influenced mating success, with correlational selection favoring particular trait combinations. Despite these two traits functionally interacting during mating, we found no evidence for their correlated evolution at macro- or microevolutionary scales. In contrast, we did uncover correlated evolution of modified vertebral hemal spines (part of the novel body region) and gonopodial anterior transposition at both evolutionary scales, matching predictions of developmental connections between these components. Developmental linkages in the ano-urogenital region apparently play key roles in evolutionary trajectories, but multiple selective agents likely act on gonopodium length and cause less predictable evolution. Within Bahamas mosquitofish, evolution of hemal-spine morphology, and gonopodial anterior transposition across predation regimes was quite predictable, with populations evolving under high predation risk showing more modified hemal spines with greater modifications and a more anteriorly positioned gonopodium. These changes in the ano-urogenital vertebral region have facilitated adaptive divergence in swimming abilities and body shape between predation regimes. Gonopodium surface area, but not length, evolved as predicted in Bahamas mosquitofish, consistent with a previously suggested tradeoff between natural and sexual selection on gonopodium size. These results provide insight into how restructured body plans offer novel evolutionary solutions. Here, a novel body region—originally evolved to aid sperm transfer—was apparently co-opted to alter whole-organism performance, facilitating phenotypic diversification.

Genetic defects in sterol synthesis, absorption, and degradation into bile acids

2011 ◽  
pp. 1673-1676
Author(s):  
Stefano Romeo
Keyword(s):  
Membrane Permeability ◽  
Bile Acids ◽  
Steroid Hormones ◽  
Cell Membranes ◽  
De Novo ◽  
Cholesterol Metabolism ◽  
The Body ◽  
Sterol Synthesis ◽  
Genetic Defects ◽  
And Function

Cholesterol is the most abundant steroid in animals. Not only is it a vital constituent of cell membranes, where it establishes proper membrane permeability and fluidity, but it is also the immediate metabolic precursor of all known steroid hormones and bile acids. Synthesized de novo in cells or absorbed from the diet, cholesterol circulates in the body in association with lipoproteins and is ultimately degraded into bile acids by the liver. Every perturbation of the numerous enzymes involved in cholesterol metabolism leads to impairment in the development and function of the gastrointestinal, cardiovascular, skeletal, and nervous systems.

Establishing The Body Plan

2020 ◽  
pp. 81-88
Author(s):  
Natalie L. Smith ◽  
David Kimelman
Keyword(s):  
Body Plan ◽  
The Body
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