An experimental investigation into the early development of the chick elbow joint

Development ◽  
1977 ◽  
Vol 39 (1) ◽  
pp. 115-127
Author(s):  
N. Holder
Keyword(s):  
Experimental Investigation ◽  
Pattern Formation ◽  
Early Development ◽  
Elbow Joint ◽  
Cell Types ◽  
Joint Region ◽  
Differential Growth ◽  
Joint Formation ◽  
Early Stages ◽  
Wing Bud

The theory that differential growth of opposed chondrogenic centres is important in early joint formation has been tested experimentally by removing structures in relation to the chick elbow joint. The humerus and its cap of differentiating joint cells were found to develop independently of structures distal to them. Removal of the presumptive joint region at early stages resulted in fusion of the humerus with the radius and ulna. Results are discussed in terms of concepts concerning pattern formation of cell types in the early wing-bud.

scholarly journals Phyllotactic pattern formation in early stages of cactus ontogeny

2011 ◽  
Vol 75 (4) ◽  
pp. 271-279 ◽  
Author(s):  
Edyta M. Gola
Keyword(s):  
Pattern Formation ◽  
Plant Growth ◽  
Early Development ◽  
Phyllotactic Pattern ◽  
Early Stages ◽  
Wide Range ◽  
The Family

Representatives of the family <em>Cactaceae</em> are characterized by a wide range of phyllotaxis. To assess the origin of this diversity, early stages of phyllotactic pattern formation were examined in seedlings. The analysis of the sequence of areole initiation revealed intertribal differences. In seedlings from the <em>Trichocereeae</em> (<em>Gymnocalycium</em>, <em>Rebutia</em>) and <em>Notocacteae</em> (<em>Parodia</em>) tribes, two opposite cotyledonal areoles developed as the first elements of a pattern. Usually, next pair of areoles was initiated perpendicularly to cotyledonal areoles, starting the decussate pattern. This pattern was subsequently transformed into bijugate or into simple spiral phyllotaxis. In seedlings from the <em>Cacteae</em> tribe (<em>Mammillaria</em> and <em>Thelocactus</em>), cotyledonal areoles were never observed and the first areoles always appeared in the space between cotyledons. It was either areole pair (mainly in <em>Mammillaria</em>), starting a decussate pattern, or a single areole (mainly in <em>Thelocactus</em>) quickly followed by areoles spirally arranged, usually in accordance with the main Fibonacci phyllotaxis. Differences in the initial stages of pattern formation do not fully explain the phyllotaxis diversity in mature cacti. Only two, the most common phyllotactic patterns occurred in the early development of studied seedlings, i.e. the main Fibonacci and the decussate pattern. Discrepancy in the range of phyllotactic spectra in seedlings and in mature plants suggests that phyllotaxis diversity emerges during further plant growth. Initial phyllotactic transformations, occurring already in the very early stages, indicate great plasticity of cactus growth and seem to support the hypothesis of the ontogenetic increase of phyllotaxis diversity due to transformations.

Autonomous expression of tissue-specific genes in dissociated sea urchin embryos

Development ◽  
1989 ◽  
Vol 107 (2) ◽  
pp. 299-307 ◽  
Author(s):  
L. Stephens ◽  
T. Kitajima ◽  
F. Wilt
Keyword(s):  
Early Development ◽  
Sea Urchin ◽  
Single Cells ◽  
Cell Types ◽  
Cell Interactions ◽  
Cell Stage ◽  
Tissue Specific ◽  
Specific Transcript ◽  
Sea Urchin Embryos ◽  
Early Stages

The effects of disrupting cell interactions in early development were investigated by examining the accumulation of a primary mesenchyme specific transcript (SM50) and an aboral ectoderm-specific transcript (Spec 1) in cultures of sea urchin embryos that were dissociated at early stages and then cultured in CFSW. The expression of both SM50 and Spec 1 is temporally correct and remains restricted to the appropriate cell types, even if the embryo is dissociated as early as the 2-cell stage and maintained as a suspension of single cells. This result is consistent with the idea that the specificity of expression of these two genes, each characteristic of different lineages, is strongly regulated by information in the egg. Average SM50 expression is half that of intact embryos, but Spec 1 expression is very low, only 10–20% of intact controls, suggesting some differences in the response of the two genes to lack of close cell interactions.

scholarly journals Differential growth is a critical determinant of zebrafish pigment pattern formation

2021 ◽  
Author(s):  
Robert N. Kelsh ◽  
Jennifer P. Owen ◽  
Christian A. Yates
Keyword(s):  
Pattern Formation ◽  
Pigment Cell ◽  
Model Organism ◽  
Cell Types ◽  
Wild Type ◽  
Differential Growth ◽  
Critical Determinant ◽  
Pigment Pattern ◽  
Pattern Development ◽  
Mechanistic Basis

The skin patterns of vertebrates are formed by complex interactions between pigment-producing cells during development. Adult zebrafish (Danio rerio), a model organism for investigating the underlying patterning processes, display alternating horizontal blue and golden stripes, generated by the self-organisation of three pigment cell-types. Mathematical studies in which these cells are modelled as individual agents communicating via short- and long-range interactions have produced breakthroughs in the understanding of pattern development. These models, incorporating all experimentally evidenced cell-cell interactions, replicate many aspects of wild-type and mutant zebrafish patterns. Although received wisdom suggested that initial iridophore distribution was pivotal in orienting patterning, here we show that growth can override its influence. Altered growth sequences can generate further pattern modulation, including vertical stripes and maze-like patterns. We demonstrate that ventrally-biased (asymmetric) growth of the skin field explains two key zebrafish pattern development features which are otherwise obscure (dorso-ventral pattern asymmetry, and predominant ventral-to-dorsal migration of melanophores) in wild-type and multiple zebrafish mutants, and in the related species Danio nigrofasciatus. By identifying biased growth as a novel patterning mechanism, our study will inform future investigations into the mechanisms and evolution of fish pigment patterning and vertebrate pigment pattern formation. Furthermore, our work has implications for the mechanistic basis of human pigmentation defects.

scholarly journals Single-cell atlas of early human brain development highlights heterogeneity of human neuroepithelial cells and early radial glia

2021 ◽  
Author(s):  
Ugomma C. Eze ◽  
Aparna Bhaduri ◽  
Maximilian Haeussler ◽  
Tomasz J. Nowakowski ◽  
Arnold R. Kriegstein
Keyword(s):  
Human Brain ◽  
Brain Development ◽  
Single Cell ◽  
Radial Glia ◽  
Cortical Development ◽  
Cell Types ◽  
Human Cortex ◽  
Early Stages ◽  
Human Brain Development ◽  
Neuroepithelial Cells

AbstractThe human cortex comprises diverse cell types that emerge from an initially uniform neuroepithelium that gives rise to radial glia, the neural stem cells of the cortex. To characterize the earliest stages of human brain development, we performed single-cell RNA-sequencing across regions of the developing human brain, including the telencephalon, diencephalon, midbrain, hindbrain and cerebellum. We identify nine progenitor populations physically proximal to the telencephalon, suggesting more heterogeneity than previously described, including a highly prevalent mesenchymal-like population that disappears once neurogenesis begins. Comparison of human and mouse progenitor populations at corresponding stages identifies two progenitor clusters that are enriched in the early stages of human cortical development. We also find that organoid systems display low fidelity to neuroepithelial and early radial glia cell types, but improve as neurogenesis progresses. Overall, we provide a comprehensive molecular and spatial atlas of early stages of human brain and cortical development.

scholarly journals Alkaloid Biosynthesis in the Early Stages of the Germination of Argemone mexicana L. (Papaveraceae)

Plants ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 2226
Author(s):  
Jorge Xool-Tamayo ◽  
Yahaira Tamayo-Ordoñez ◽  
Miriam Monforte-González ◽  
José Armando Muñoz-Sánchez ◽  
Felipe Vázquez-Flota
Keyword(s):  
Gene Expression ◽  
Tissue Distribution ◽  
Early Development ◽  
Transcriptional Activity ◽  
Seedling Development ◽  
Transport Systems ◽  
Alkaloid Biosynthesis ◽  
Argemone Mexicana ◽  
Early Stages ◽  
Low Levels

The synthesis of the benzylisoquinoline alkaloids, sanguinarine and berberine, was monitored in Argemone mexicana L. (Papaveracea) throughout the early stages of its hypocotyl and seedling development. Sanguinarine was detected in the cotyledons right after hypocotyl emergence, and it increased continuously until the apical hook unbent, prior to the cotyledonary leaves unfolding, when it abruptly fell. In the cotyledonary leaves, it also remained at low levels. Throughout development, berberine accumulation required the formation of cotyledonary leaves, whereas it was quickly detected in the hypocotyl from the time it emerged. Interestingly, the alkaloids detected in the cotyledons could have been imported from hypocotyls, because no transcriptional activity was detected in there. However, after turning into cotyledonary leaves, important levels of gene expression were noted. Taken together, these results suggest that the patterns of alkaloid tissue distribution are established from very early development, and might require transport systems.

XCL100, an inducible nuclear MAP kinase phosphatase from Xenopus laevis: its role in MAP kinase inactivation in differentiated cells and its expression during early development

1995 ◽  
Vol 108 (8) ◽  
pp. 2885-2896 ◽  
Author(s):  
T. Lewis ◽  
L.A. Groom ◽  
A.A. Sneddon ◽  
C. Smythe ◽  
S.M. Keyse
Keyword(s):  
Xenopus Laevis ◽  
Map Kinase ◽  
Early Development ◽  
Nuclear Translocation ◽  
Cell Types ◽  
Differentiated Cells ◽  
Serum Stimulation ◽  
Transient Activation ◽  
Map Kinase Phosphatase

We have cloned the Xenopus laevis homologue (XCL100) of the human CL100 (Thr/Tyr) MAP kinase phosphatase. Expression of the XCL100 mRNA and protein is inducible by serum stimulation and oxidative/heat stress in a X. laevis kidney cell line. In contrast, XCL100 is constitutively expressed in growing Xenopus oocytes. Recombinant XCL100 protein is able to dephosphorylate both tyrosine and threonine residues of activated p42 MAP kinase in vitro and both the Xenopus and human CL100 proteins were localised predominantly in the nucleus in transfected COS-1 cells. As nuclear translocation of activated MAP kinase is necessary for some of its essential functions in proliferation and cell differentiation our results indicate a role for CL100 in the regulation of these nuclear signalling events. In Xenopus kidney cells both heat shock and serum stimulation lead to transient activation of MAP kinase. However, in contrast to results previously reported from studies on mammalian fibroblasts the inactivation of MAP kinase in these epitheloid cells is rapid and is not dependent on synthesis of new protein. These results indicate that the induction of CL100 (or CL100-like enzymes) may not be required for MAP kinase inactivation in all cell types. Finally, during early embryogenesis, levels of XCL100 mRNA are greatly increased at the mid-blastula transition, suggesting that this enzyme may be involved in the regulation of MAP kinase activity during early development.

Cell contacts and sorting out in vivo: the behaviour of some embryonic tissues implanted into the developing chick wing

Development ◽  
1978 ◽  
Vol 48 (1) ◽  
pp. 225-237
Author(s):  
C. Tickle ◽  
M. Goodman ◽  
L. Wolpert
Keyword(s):  
Neural Tube ◽  
Cell Types ◽  
Neural Retina ◽  
Limb Bud ◽  
Embryonic Liver ◽  
Malignant Cells ◽  
Embryonic Tissues ◽  
Mixed Aggregates ◽  
Wing Bud

The interaction of cells from embryonic liver, neural retina and mesonephros with cells from limb-bud mesenchyme has been investigated in vivo by grafting these tissues into the developing chick wing-bud. The implanted cells were in all cases from quail tissue which can be recognized histologically. As embryonic liver and neural tube are tissues that sort externally to limb-bud mesenchyme in mixed aggregates, it would be expected, from a differential adhesiveness hypothesis, that heterotypic adhesions along the borders of graft and host would be favoured over cell-cell adhesions in the graft. No morphological signs of this were evident: rather the grafted cells maximized like-like contacts. The cells of the grafts, including those from control mesenchyme, did not invade into the wing. The results were the same irrespective of whether the graft was a fragment of tissue or a pellet of reaggregated cells. This supports the idea that cells within tissues are not actively moving around and also provides controls for assaying the invasiveness of other cell types, such as malignant cells into the wing.

Experiments in vitro on the Role of Movement in the Development of Joints

Development ◽  
1958 ◽  
Vol 6 (2) ◽  
pp. 183-186
Author(s):  
G. Lelkes
Keyword(s):  
Nerve Supply ◽  
Essential Factor ◽  
Differential Growth ◽  
Joint Formation ◽  
Articular Surfaces ◽  
Early Formation ◽  
Further Development

It has been pointed out by Fell & Canti (1934) as a result of their experiments in vitro concerning the early formation of the avian limb skeleton and kneejoint, that the appearance of the articular rudiment is independent of the bloodand nerve-supply as well as of mechanical influences. These authors believe that the formation of articular surfaces occurs in consequence of the differential growth of the scleroblastema (the ‘Anlage’ of the limb skeleton, skeletal rudiment) the essential factor in joint formation being the association of undifferentiated tissue with the rapidly growing chondrification centres. They emphasize, however, that only the earlier stages of joint formation can be obtained in vitro, the conditions of cultivation are not adequate for the further development of the joints. The articular rudiment disappears by secondary fusion of the cartilages of the limb skeleton.

Model for Digital Economy in Indonesia

2013 ◽  
pp. 60-77
Author(s):  
Vincent Didiek Wiet Aryanto ◽  
Agnes Advensia Chrismastuti
Keyword(s):  
Central Bank ◽  
Real Time ◽  
Early Development ◽  
Value Creation ◽  
Response Rate ◽  
Distribution Channels ◽  
Digital Economy ◽  
Online Research ◽  
Business Activity ◽  
Early Stages

This study introduces the early development of digital economy in Indonesia. e-Business activity is growing at an unprecedented rate in Indonesia as indicated by the number of online real time transactions (Real Time Gross Settlement) recorded by Bank Indonesia (Indonesian Central Bank), the emergence of dotcom companies, and the use of ICT in conventional business (a combination of brick & mortar with click/online). Research was conducted by investigating the digital activities of businesses. Unfortunately out of the 109 businesses approached, response rate was very poor with only 30 responding (27%). This is not uncommon in Indonesia for a variety of reasons. Results from the four variables utilized in this study, e-Distribution Channels, Value Creation, Online Products & Services, and Online Infrastructures, indicate that the development of digital economy in Indonesia is still in its early stages due to a number of encountered obstacles.

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