scholarly journals Heterogeneity of proteoglycans in developing chick limb cartilage

1977 ◽  
Vol 164 (1) ◽  
pp. 179-183 ◽  
Author(s):  
N S Vasan ◽  
J W Lash
Keyword(s):  
Limb Bud ◽  
Embryonic Chick ◽  
Regulatory Factor ◽  
Limb Buds ◽  
Link Protein

Proteoglycan heterogeneity was studied during the maturation of embryonic-chick limb cartilage in vivo. The results suggest that during the differentiation of limb-bud cartilage the aggregated forms of proteoglycans increase between stages 24 and 35, whereas the non-aggregated or monomeric forms decrease. Only one link protein is found in stage-24 limb buds, whereas two are present at stage 35. Evidence suggests that the synthesis of link proteins may be a regulatory factor in limb chondrogenesis.

The genesis of membrane bone in the embryonic chick maxilla: epithelial-mesenchymal tissue recombination studies

Development ◽  
1980 ◽  
Vol 56 (1) ◽  
pp. 269-281
Author(s):  
Mary S. Tyler ◽  
David P. McCobb
Keyword(s):  
Bone Formation ◽  
Hind Limb ◽  
Bone Grafts ◽  
Chick Embryos ◽  
Embryonic Chick ◽  
Limb Buds ◽  
Mesenchymal Tissue ◽  
Membrane Bone ◽  
Tissue Recombination

In the present study, the question of whether a relatively non-specific epithelial requirement exists for membrane bone formation within the maxillary mesenchyme was investigated. Organ rudiments from embryonic chicks of three to five days of incubation (HH 18–25) were enzymatically separated into the epithelial and mesenchymal components. Maxillarymesenchyme (from embryos HH 18–19) which in the absence of epithelium will not form bone was recombined with epithelium from maxillae of similarly aged embryos (homotypichomochronic recombination) and of older embryos (HH 25) (homotypic-heterochronicrecombination). Heterotypic recombinations were made between maxillary mesenchyme (HH 18–19) and the epithelium from wing and hind-limb buds (HH 19–22). Recombinants were grown as grafts on thechorioallantoic membranes of host chick embryos. Grafts of intact maxillae, isolated maxillary mesenchyme, and isolated epithelia from the maxilla, wing-, and hind-limb buds weregrown as controls. The histodifferentiation of grafted intact maxillae was similar to that in vivo; both cartilage and membrane bone differentiated within the mesenchyme. Grafts of maxillary mesenchyme (from embryos HH 18–19) grown in the absence of epithelium formed cartilage but did not form membrane bone. Grafts of maxillary mesenchyme (from embryos HH 18–19) recombined with epithelium in homotypichomochronic, homotypic-heterochronic, and heterotypic tissue combinations formed membrane bone in addition to cartilage. These results indicate that maxillary mesenchyme requires the presence of epithelium to promote osteogenesis and that this epithelial requirement is relatively non-specific in terms of type and age of epithelium.

Distribution of nestin in the developing mouse limb bud in vivo and in micro-mass cultures of cells isolated from limb buds

1997 ◽  
Vol 61 (3) ◽  
pp. 151-159 ◽  
Author(s):  
Joanna Wroblewski ◽  
Marianne Engström ◽  
Caroline Edwall-Arvidsson ◽  
Gunnar Sjöberg ◽  
Thomas Sejersen ◽  
...  
Keyword(s):  
Limb Bud ◽  
Limb Buds ◽  
Mass Cultures ◽  
Mouse Limb

A gradation of hyaluronate accumulation along the proximodistal axis of the embryonic chick limb bud

Development ◽  
1981 ◽  
Vol 63 (1) ◽  
pp. 85-98
Author(s):  
Robert A. Kosher ◽  
Mary P. Savage ◽  
Kordasey H. Walker
Keyword(s):  
Chondroitin Sulphate ◽  
Distal Segment ◽  
Limb Bud ◽  
Central Core ◽  
Embryonic Chick ◽  
Limb Buds ◽  
Progressive Decline ◽  
Negative Effect ◽  
Core Tissue ◽  
Region Segment

We are currently investigating the mechanism by which the apical ectodermal ridge (AER) of the embryonic chick limb bud exerts its negative effect on the cytodifferentiation of limb mesenchymal cells directly subjacent to it, and the mechanism by which cytodifferentiation is triggered when the cells leave the influence of the AER. Since there is a gradation of differentiation along the proximodistal axis of the limb bud, we have dissected limb buds into discrete segments along the proximodistal axis, and biochemically examined the accumulation of hyaluronate (HA) and other glycosaminoglycans (GAG) in each segment. The unspeciajized subridge region of stage-25 limb buds was separated into distal (segment 1) and proximal (segment 2) regions, and the remaining proximal portion of the limb was separated into four segments (segments 3, 4, 5 and 6) along the proximodistal axis. Stage-24 limb buds were separated into corresponding regions. Since in the proximal regions of the limb (segment 3 through 6), only the cells comprising the central cores of the limb are involved in chondrogenic differentiation, the central core tissue was surgically separated from the peripheral tissue. We have found that HA is by far the predominant GAG accumulated by cells comprising the distal subridge region (representing greater than 50% of the total GAG accumulated during a 90-min labelling period with [3H]glucosamine), and that there is a progressive decline in HA accumulation along the proximodistal axis. The relative and total amount of HA accumulated is highest in the distal subridge region (segment 1), intermediate i(i the proximal subridge region (segment 2) and lowest in the proximal central core regions Of the limb (segments 3 through 6). The striking decrease in HA accumulation in the central core of segment 3 is accompanied by a striking increase in the accumulation of chondroitin sulphate, one of the major constituents of cartilage matrix. In contrast to the central core regions of segments 3 through 6, the relative and total amount of HA accumulated by the peripheral non-chondrogenic regions of these segments remains relatively high, being similar to the accumulation observed in the proximal subridge region. These results indicate that there is a gradation of HA accumulation along the proximodistal axis of both stages-24 and -25 limb buds which correlates with distance of cells from the AER and the state of differentiation of the cells.

An analysis of the condensation process during chondrogenesis in the embryonic chick hind limb

Development ◽  
1975 ◽  
Vol 33 (3) ◽  
pp. 581-606
Author(s):  
P. V. Thorogood ◽  
J. R. Hinchliffe
Keyword(s):  
Hind Limb ◽  
Mesenchymal Cell ◽  
Cell Number ◽  
Limb Bud ◽  
Condensation Process ◽  
Embryonic Chick ◽  
Cellular Events ◽  
Cell Counts

An analysis has been made of the pre-cartilaginous condensation stage in the development of the femur and tibia/fibula skeletal blastemata of the embryonic chick hind limb. Light microscopy serial sections were used to ‘map’ the mesenchymal cell condensations of both myogenic and chondrogenic anlagen in the limb-bud from stages 22 to 26 (Hamburger & Hamilton, 1951). Cell counts reveal that an increase in mesenchymal cell number per unit area occurs in the central chondrogenic locus at stage 24 (4½ days) prior to matrix formation. Electron microscopy, using a simultaneous double fixation with osmium and glutaraldehyde, reveals that the pre-chondrogenic cells are characterized by large areas of close surface contact between adjacent cells, as compared with the extensive intercellular spaces associated with undifferentiated mesenchymal cells. The results are discussed and related to other investigations of in vivo chondrogenesis and to analyses of cellular events during in vitro chondrogenesis. These observations are consistent with the theory that condensations are formed by a process of aggregation rather than by localized increased mitosis.

IGF-I, insulin and FGFs induce outgrowth of the limb buds of amelic mutant chick embryos

Development ◽  
1996 ◽  
Vol 122 (4) ◽  
pp. 1323-1330 ◽  
Author(s):  
C.N. Dealy ◽  
R.A. Kosher
Keyword(s):  
Proper Time ◽  
Limb Bud ◽  
Chick Embryos ◽  
In Vitro Morphogenesis ◽  
Limb Buds ◽  
Limb Outgrowth ◽  
Igf I ◽  
High Level

IGF-I, insulin, FGF-2 and FGF-4 have been implicated in the reciprocal interactions between the apical ectodermal ridge (AER) and underlying mesoderm required for outgrowth and patterning of the developing limb. To study further the roles of these growth factors in limb outgrowth, we have examined their effects on the in vitro morphogenesis of limb buds of the amelic mutant chick embryos wingless (wl) and limbless (ll). Limb buds of wl and ll mutant embryos form at the proper time in development, but fail to undergo further outgrowth and subsequently degenerate. Wl and ll limb buds lack thickened AERs capable of promoting limb outgrowth, and their thin apical ectoderms fail to express the homeobox-containing gene Msx-2, which is highly expressed by normal AERs and has been implicated in regulating AER activity. Here we report that exogenous IGF-I and insulin, and, to a lesser extent, FGF-2 and FGF-4 induce the proliferation and directed outgrowth of explanted wl and ll mutant limb buds, which in vitro, like in vivo, normally fail to undergo outgrowth and degenerate. IGF-I and insulin, but not FGFs, also cause the thin apical ectoderms of wl and ll limb buds to thicken and form structures that grossly resemble normal AERs and, moreover, induce high level expression of Msx-2 in these thickened AER-like structures. Neither IGF-I, insulin nor FGFs induce expression of the homeobox-containing gene Msx-1 in the subapical mesoderm of wl or ll limb buds, although FGFs, but not IGF-I or insulin, maintain Msx-1 expression in normal (non-mutant) limb bud explants lacking an AER. The implications of these results to the relationships among the wl and ll genes, IGF-I/insulin, FGFs, Msx-2 and Msx-1 in the regulation of limb outgrowth is discussed.

scholarly journals Development of a potent embryonic chick lens model for studying congenital cataracts in vivo

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Zhen Li ◽  
Sumin Gu ◽  
Yumeng Quan ◽  
Kulandaiappan Varadaraj ◽  
Jean X. Jiang
Keyword(s):  
Light Transmission ◽  
Genetic Diseases ◽  
Gene Mutations ◽  
Underlying Mechanism ◽  
Dominant Negative ◽  
Lens Model ◽  
Embryonic Chick ◽  
Congenital Cataracts ◽  
Chick Lens

AbstractCongenital cataracts are associated with gene mutations, yet the underlying mechanism remains largely unknown. Here we reported an embryonic chick lens model that closely recapitulates the process of cataract formation. We adopted dominant-negative site mutations that cause congenital cataracts, connexin, Cx50E48K, aquaporin 0, AQP0R33C, αA-crystallin, CRYAA R12C and R54C. The recombinant retroviruses containing these mutants were microinjected into the occlusive lumen of chick lenses at early embryonic development. Cx50E48K expression developed cataracts associated with disorganized nuclei and enlarged extracellular spaces. Expression of AQP0R33C resulted in cortical cataracts, enlarged extracellular spaces and distorted fiber cell organization. αA crystallin mutations distorted lens light transmission and increased crystalline protein aggregation. Together, retroviral expression of congenital mutant genes in embryonic chick lenses closely mimics characteristics of human congenital cataracts. This model will provide an effective, reliable in vivo system to investigate the development and underlying mechanism of cataracts and other genetic diseases.

scholarly journals Experimental studies on the differentiation of embryonic tissues growing in vivo and in vitro .—II. The development of the isolated early embryonic eye of the fowl when cultivated in vitro

1926 ◽  
Vol 100 (703) ◽  
pp. 273-283 ◽  
Keyword(s):  
Medical Research ◽  
Research Council ◽  
Medical Research Council ◽  
Experimental Studies ◽  
Limb Bud ◽  
Progressive Development ◽  
Embryonic Tissues ◽  
Self Differentiation

In a previous communication (Strangeways and Fell, 1926) it was shown that if the undifferentiated limb-bud of the embryonic Fowl was cultivated in vitro , it underwent a considerable amount of progressive development. This capacity for independent development in vitro possessed by an isolated organ has been further investigated, and for these later experiments the writers have employed the early embryonic eye, a structure endowed with more complex potentialities than the limb-bud. As a result of these experiments it was found that the eyes of young Fowl embryos possess, in a remarkable degree, the faculty for self-differentiation in vitro and for “organotypic” growth as defined by Maximow (1925). The previous work on organotypic growth in vitro has already been briefly outlined in the writers’ earlier paper and need not be discussed here. The expenses connected with the experiments described in this communication were met by the Medical Research Council, to whom the writers desire to express their thanks.

scholarly journals USP1–UAF1 deubiquitinase complex stabilizes TBK1 and enhances antiviral responses

2017 ◽  
Vol 214 (12) ◽  
pp. 3553-3563 ◽  
Author(s):  
Zhongxia Yu ◽  
Hui Song ◽  
Mutian Jia ◽  
Jintao Zhang ◽  
Wenwen Wang ◽  
...  
Keyword(s):  
Viral Infection ◽  
Degradation Process ◽  
Viral Diseases ◽  
Immune Homeostasis ◽  
Regulatory Factor ◽  
Antiviral Responses ◽  
Innate Antiviral Immunity ◽  
Irf3 Activation

Optimal activation of TANK-binding kinase 1 (TBK1) is crucial for initiation of innate antiviral immunity and maintenance of immune homeostasis. Although several E3 ubiquitin ligases have been reported to regulate TBK1 activation by mediating its polyubiquitination, the functions of deubiquitinase on TBK1 activity remain largely unclear. Here, we identified a deubiquitinase complex, which is formed by ubiquitin specific peptidase 1 (USP1) and USP1-associated factor 1 (UAF1), as a viral infection–induced physiological enhancer of TBK1 expression. USP1–UAF1 complex enhanced TLR3/4 and RIG-I–induced IFN regulatory factor 3 (IRF3) activation and subsequent IFN-β secretion. Mechanistically, USP1 and UAF1 bound to TBK1, removed its K48-linked polyubiquitination, and then reversed the degradation process of TBK1. Furthermore, we found that ML323, a specific USP1–UAF1 inhibitor, attenuated IFN-β expression and enhanced viral replication both in vitro and in vivo. Therefore, our results outline a novel mechanism for the control of TBK1 activity and suggest USP1–UAF1 complex as a potential target for the prevention of viral diseases.

FGF-4 maintains polarizing activity of posterior limb bud cells in vivo and in vitro

Development ◽  
1993 ◽  
Vol 119 (1) ◽  
pp. 199-206 ◽  
Author(s):  
A. Vogel ◽  
C. Tickle
Keyword(s):  
Posterior Margin ◽  
Anterior Margin ◽  
Marked Decrease ◽  
Mesenchymal Cells ◽  
Apical Ectodermal Ridge ◽  
Limb Bud ◽  
Posterior Limb ◽  
Vertebrate Limb

The polarizing region is a major signalling tissue involved in patterning the tissues of the vertebrate limb. The polarizing region is located at the posterior margin of the limb bud and can be recognized by its ability to induce additional digits when grafted to the anterior margin of a chick limb bud. The signal from the polarizing region operates at the tip of the bud in the progress zone, a zone of undifferentiated mesenchymal cells, maintained by interactions with the apical ectodermal ridge. A number of observations have pointed to a link between the apical ectodermal ridge and signalling by the polarizing region. To test this possibility, we removed the posterior apical ectodermal ridge of chick wing buds and assayed posterior mesenchyme for polarizing activity. When the apical ectodermal ridge is removed, there is a marked decrease in polarizing activity of posterior cells. The posterior apical ectodermal ridge is known to express FGF-4 and we show that the decrease in polarizing activity of posterior cells of wing buds that normally follows ridge removal can be prevented by implanting a FGF-4-soaked bead. Furthermore, we show that both ectoderm and FGF-4 maintain polarizing activity of limb bud cells in culture.

Conservation of Pitx1 expression during amphibian limb morphogenesis

2006 ◽  
Vol 84 (2) ◽  
pp. 257-262 ◽  
Author(s):  
W Y Chang ◽  
F KhosrowShahian ◽  
M Wolanski ◽  
R Marshall ◽  
W McCormick ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Xenopus Laevis ◽  
Expression Patterns ◽  
Limb Bud ◽  
Eleutherodactylus Coqui ◽  
Limb Buds ◽  
Homeodomain Transcription Factor ◽  
Limb Morphogenesis ◽  
Pelvic Limb

In contrast to the pattern of limb emergence in mammals, chicks, and the newt N. viridescens, embryos such as Xenopus laevis and Eleutherodactylus coqui initiate pelvic limb buds before they develop pectoral ones. We studied the expression of Pitx1 in X. laevis and E. coqui to determine if this paired-like homeodomain transcription factor directs differentiation specifically of the hindlimb, or if it directs the second pair of limbs to form, namely the forelimbs. We also undertook to determine if embryonic expression patterns were recapitulated during the regeneration of an amputated limb bud. Pitx1 is expressed in hindlimbs in both X. laevis and E. coqui, and expression is similar in both developing and regenerating limb buds. Expression in hindlimbs is restricted to regions of proliferating mesenchyme.Key words: regeneration, Xenopus laevis, limb bud, Pitx1 protein, specification.

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