An interaction between dorsal and ventral regions of the marginal zone in early amphibian embryos

When small explants from early gastrulae of Xenopus laevis are allowed to develop in abuffered salt solution there is a considerable difference between the patterns of differentiation obtained from different dorsoventral levels of the marginal zone. These patternsof differentiation correspond to the fates of the different regions in the course of normal development. They are not altered if several explants of the same type are fused before culture. If a ventral marginal zone explant from Xenopus is cultured in contact with a piece of dorsal marginal zone from the axolotl, it forms structures more dorsal in character than it would in isolation or in normal development. This behaviour is shown only feebly with other regions of the axolotl gastrula. A piece of dorsal marginal zone from Xenopus is not affected in its development by culture in contact with an explant of ventral marginal zone from the axolotl. The dorsalization of ventral marginal zone explants is shown only if there is a large area of direct contact with the dorsal explant and if the pieces remain in contact for a period of 48 h or more. It is proposed that this in vitro interaction is the same as the dorsoventral component of action of the ‘organizer’ graft discovered by Spemann and Mangold.

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Regional specification within the mesoderm of early embryos of Xenopus laevis

Development ◽

10.1242/dev.100.2.279 ◽

1987 ◽

Vol 100 (2) ◽

pp. 279-295 ◽

Cited By ~ 24

Author(s):

L. Dale ◽

J.M. Slack

Keyword(s):

Xenopus Laevis ◽

Marginal Zone ◽

Mesoderm Induction ◽

Intermediate Type ◽

Cell Stage ◽

Early Embryos ◽

Significant Difference ◽

Cell Embryo ◽

Single Blastomeres

We have further analysed the roles of mesoderm induction and dorsalization in the formation of a regionally specified mesoderm in early embryos of Xenopus laevis. First, we have examined the regional specificity of mesoderm induction by isolating single blastomeres from the vegetalmost tier of the 32-cell embryo and combining each with a lineage-labelled (FDA) animal blastomere tier. Whereas dorsovegetal (D1) blastomeres induce ‘dorsal-type’ mesoderm (notochord and muscle), laterovegetal and ventrovegetal blastomeres (D2–4) induce either ‘intermediate-type’ (muscle, mesothelium, mesenchyme and blood) or ‘ventral-type’ (mesothelium, mesenchyme and blood) mesoderm. No significant difference in inductive specificity between blastomeres D2, 3 and 4 could be detected. We also show that laterovegetal and ventrovegetal blastomeres from early cleavage stages can have a dorsal inductive potency partially activated by operative procedures, resulting in the induction of intermediate-type mesoderm. Second, we have determined the state of specification of ventral blastomeres by isolating and culturing them in vitro between the 4-cell stage and the early gastrula stage. The majority of isolates from the ventral half of the embryo gave extreme ventral types of differentiation at all stages tested. Although a minority of cases formed intermediate-type and dorsal-type mesoderms we believe these to result from either errors in our assessment of the prospective DV axis or from an enhancement, provoked by microsurgery, of some dorsal inductive specificity. The results of induction and isolation experiments suggest that only two states of specification exist in the mesoderm of the pregastrula embryo, a dorsal type and a ventral type. Finally we have made a comprehensive series of combinations between different regions of the marginal zone using FDA to distinguish the components. We show that, in combination with dorsal-type mesoderm, ventral-type mesoderm becomes dorsalized to the level of intermediate-type mesoderm. Dorsal-type mesoderm is not ventralized in these combinations. Dorsalizing activity is confined to a restricted sector of the dorsal marginal zone, it is wider than the prospective notochord and seems to be graded from a high point at the dorsal midline. The results of these experiments strengthen the case for the three-signal model proposed previously, i.e. dorsal and ventral mesoderm inductions followed by dorsalization, as the simplest explanation capable of accounting for regional specification within the mesoderm of early Xenopus embryos.

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Patterns of Particle Movement in Nerve Fibres In Vitro- an Analysis by Photokymography and Microscopy

Journal of Cell Science ◽

10.1242/jcs.11.3.875 ◽

1972 ◽

Vol 11 (3) ◽

pp. 875-886

Author(s):

M. BERLINROOD ◽

S. M. McGEE-RUSSELL ◽

R. D. ALLEN

Keyword(s):

Electron Microscopy ◽

Xenopus Laevis ◽

Particle Velocity ◽

Rana Pipiens ◽

Ambystoma Tigrinum ◽

Particle Movement ◽

Nerve Fibres ◽

Amphibian Embryos ◽

Particle Velocities

Tissue-cultured nerve fibres derived from 3 species of amphibian embryos were composed of bundles of neurites, when viewed by electron microscopy, and contained particles moving in both directions by saltations. Photokymographic analysis of ciné microscopy records taken with Zeiss differential interference optics demonstrated instantaneous particle velocities ranging from 0.15 to 1.8 µm 8-1 (13-155 mm/day) in Rana pipiens cultures; 0.16-0.8 µm s-1 (14-74 mm/day) in Ambystoma tigrinum cultures and 0.6-2.25 µm s-1 (45-194 mm/day) in Xenopus laevis cultures. Measured pathlengths for particles saltations ranged from 4 to 63 µm. No correlations between particle velocity and pathlength were found.

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Pharmacological modulation of the cAMP signaling of two isoforms of melanocortin-3 receptor by melanocortin receptor accessory proteins in the tetrapod Xenopus laevis

Endocrine Connections ◽

10.1530/ec-21-0179 ◽

2021 ◽

Author(s):

Ying Xu ◽

Lei Li ◽

Jihong Zheng ◽

Meng Wang ◽

Bopei Jiang ◽

...

Keyword(s):

Xenopus Laevis ◽

Energy Homeostasis ◽

Surface Expression ◽

Immunofluorescence Assay ◽

Melanocortin Receptor ◽

Accessory Proteins ◽

Melanocortin System ◽

Pharmacological Modulation ◽

In Vitro Interaction

As a member of the seven-transmembrane rhodopsin-like G protein-coupled receptor superfamily, the melanocortin-3 receptor is vital for the regulation of energy homeostasis and rhythms synchronizing in mammals and its pharmacological effect could be directly influenced by the presence of melanocortin accessory proteins, MRAP1 and MRAP2. The tetrapod amphibian Xenopus laevis (xl) retains higher duplicated genome than extant teleosts and serves as an ideal model system for embryonic development and physiological studies. However, the melanocortin system of the Xenopus laevis has not been thoroughly evaluated yet. In this work, we performed sequence alignment, phylogenetic and synteny analysis of two xlMC3Rs. Co-immunoprecipitation and immunofluorescence assay further confirmed the co-localization and in vitro interaction of xlMC3Rs with xlMRAPs on the plasma membrane. Our results demonstrated that xlMRAP2.L/S could improve α-MSH stimulated xlMC3Rs signaling and suppress their surface expression. Moreover, xlMC3R.L showed a similar profile on the ligands and surface expression in the presence of xlMRAP1.L. Overall, the distinct pharmacological modulation of xlMC3R.L and xlMC3R.S by dual MRAP2 proteins elucidated the functional consistency of melanocortin system during genomic duplication of tetrapod vertebrates.

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Collagen fibrillogenesis in vitro: interaction of types I and V collagen

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100142670 ◽

1986 ◽

Vol 44 ◽

pp. 210-211

Author(s):

Arthur J. Wasserman ◽

Kathy C. Kloos ◽

David E. Birk

Keyword(s):

Type I Collagen ◽

Corneal Stroma ◽

Minor Component ◽

Homogeneous Distribution ◽

Type I ◽

Type V Collagen ◽

Fibril Morphology ◽

Type V ◽

In Vitro Interaction

Type I collagen is the predominant collagen in the cornea with type V collagen being a quantitatively minor component. However, the content of type V collagen (10-20%) in the cornea is high when compared to other tissues containing predominantly type I collagen. The corneal stroma has a homogeneous distribution of these two collagens, however, immunochemical localization of type V collagen requires the disruption of type I collagen structure. This indicates that these collagens may be arranged as heterpolymeric fibrils. This arrangement may be responsible for the control of fibril diameter necessary for corneal transparency. The purpose of this work is to study the in vitro assembly of collagen type V and to determine whether the interactions of these collagens influence fibril morphology.

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Faculty Opinions recommendation of Formation of the dorsal marginal zone in Xenopus laevis analyzed by time-lapse microscopic magnetic resonance imaging.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1085816.538735 ◽

2007 ◽

Author(s):

Lance Davidson

Keyword(s):

Magnetic Resonance Imaging ◽

Magnetic Resonance ◽

Xenopus Laevis ◽

Marginal Zone ◽

Time Lapse ◽

Resonance Imaging

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Ligation of tumour-produced mucins to CD22 dramatically impairs splenic marginal zone B-cells

Biochemical Journal ◽

10.1042/bj20081241 ◽

2009 ◽

Vol 417 (3) ◽

pp. 673-683 ◽

Cited By ~ 13

Author(s):

Munetoyo Toda ◽

Risa Hisano ◽

Hajime Yurugi ◽

Kaoru Akita ◽

Kouji Maruyama ◽

...

Keyword(s):

Sialic Acid ◽

B Cells ◽

B Cell ◽

Marginal Zone ◽

Cell Signalling ◽

Negative Regulator ◽

Mammary Adenocarcinoma ◽

Marginal Zone B Cells ◽

Tumour Bearing

CD22 [Siglec-2 (sialic acid-binding, immunoglobulin-like lectin-2)], a negative regulator of B-cell signalling, binds to α2,6- sialic acid-linked glycoconjugates, including a sialyl-Tn antigen that is one of the typical tumour-associated carbohydrate antigens expressed on various mucins. Many epithelial tumours secrete mucins into tissues and/or the bloodstream. Mouse mammary adenocarcinoma cells, TA3-Ha, produce a mucin named epiglycanin, but a subline of them, TA3-St, does not. Epiglycanin binds to CD22 and inhibits B-cell signalling in vitro. The in vivo effect of mucins in the tumour-bearing state was investigated using these cell lines. It should be noted that splenic MZ (marginal zone) B-cells were dramatically reduced in the mice bearing TA3-Ha cells but not in those bearing TA3-St cells, this being consistent with the finding that the thymus-independent response was reduced in these mice. When the mucins were administered to normal mice, a portion of them was detected in the splenic MZ associated with the MZ B-cells. Furthermore, administration of mucins to normal mice clearly reduced the splenic MZ B-cells, similar to tumour-bearing mice. These results indicate that mucins in the bloodstream interacted with CD22, which led to impairment of the splenic MZ B-cells in the tumour-bearing state.

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