Fate maps of the first quartet micromeres in the gastropod Ilyanassa obsoleta

Development ◽  
1991 ◽  
Vol 113 (2) ◽  
pp. 495-501 ◽  
Author(s):  
J. Render
Keyword(s):  
Cell Fate ◽  
Lucifer Yellow ◽  
Cell Lineage ◽  
Ilyanassa Obsoleta ◽  
Cell Fate Specification ◽  
Polar Lobe ◽  
Gastropod Mollusc ◽  
Cell Ablation ◽  
Critical Interpretation ◽  
Complete Cell

Cell fate specification in the gastropod mollusc Ilyanassa obsoleta involves both cell autonomous and inductive mechanisms, which depend on determinants localized first in the polar lobe and then in the D quadrant of the embryo. A complete cell lineage is lacking for this embryo and is essential for a critical interpretation of previous experimental results and an analysis of the mechanisms at the molecular level. Lineages of the first quartet micromeres were followed using Lucifer Yellow dextran as a tracer. The tracer was injected into individual first quartet micromeres using iontophoresis and patterns of fluorescence were analyzed in the larva after 8 days of development. Fluorescence was limited to head structures, including eyes, tentacles and velum. Structures on the left side were derived from 1a and 1d micromeres; 1a gave rise to the left eye, including the lens. Right side structures were derived from the 1c micromere and 1b contributed to the apical plate between the eyes and symmetrically to both sides of the velum. First quartet lineage data are compared with results from previous cell ablation experiments and with lineage data from other species.

Evolutionary changes of developmental mechanisms in the absence of cell lineage alterations during vulva formation in the Diplogastridae (Nematoda)

Development ◽  
1997 ◽  
Vol 124 (1) ◽  
pp. 243-251 ◽  
Author(s):  
R.J. Sommer
Keyword(s):  
Cell Fate ◽  
Cell Fusion ◽  
Genetic Model ◽  
Cell Lineage ◽  
Model Organism ◽  
Epidermal Cells ◽  
Cell Fate Specification ◽  
Fate Specification ◽  
Developmental Mechanisms ◽  
Differentiation Pattern

The origin of novelty is one of the least understood evolutionary phenomena. One approach to study evolutionary novelty comes from developmental biology. During developmental cell fate specification of the nematode Pristionchus pacificus (Diplogastridae), five cell fates can be distinguished within a group of twelve ventral epidermal cells. The differentiation pattern of individual cells includes programmed cell death, cell fusion and vulval differentiation after induction by the gonad. A cell lineage comparison among species of seven different genera of the Diplogastridae indicates that the differentiation pattern of ventral epidermal cells is highly conserved. Despite this morphological conservation, cell ablation experiments indicate many independent alterations of underlying mechanisms of cell fate specification. Cell fusion and individual cell competence change during evolution as well as the differentiation property in response to inductive signaling. These results suggest that developmental mechanisms, some of which are redundantly involved in vulval fate specification of the genetic model organism Caenorhabditis elegans, can evolve without concomitant morphological change.

Modifications of cell fate specification in equal-cleaving nemertean embryos: alternate patterns of spiralian development

Development ◽  
1995 ◽  
Vol 121 (10) ◽  
pp. 3175-3185 ◽  
Author(s):  
M.Q. Martindale ◽  
J.Q. Henry
Keyword(s):  
Cell Fate ◽  
Cell Lineage ◽  
Cell Types ◽  
Embryonic Cell ◽  
Specific Cell ◽  
Cell Fate Specification ◽  
Cell Fates ◽  
Developmental Potential ◽  
Fate Specification ◽  
Symmetry Properties

The nemerteans belong to a phylum of coelomate worms that display a highly conserved pattern of cell divisions referred to as spiral cleavage. It has recently been shown that the fates of the four embryonic cell quadrants in two species of nemerteans are not homologous to those in other spiralian embryos, such as the annelids and molluscs (Henry, J. Q. and Martindale, M. Q. (1994a) Develop. Genetics 15, 64–78). Equal-cleaving molluscs utilize inductive interactions to establish quadrant-specific cell fates and embryonic symmetry properties following fifth cleavage. In order to elucidate the manner in which cell fates are established in nemertean embryos, we have conducted cell isolation and deletion experiments to examine the developmental potential of the early cleavage blastomeres of two equal-cleaving nemerteans, Nemertopsis bivittata and Cerebratulus lacteus. These two species display different modes of development: N. bivittata develops directly via a non-feeding larvae, while C. lacteus develops to form a feeding pilidium larva which undergoes a radical metamorphosis to give rise to the juvenile worm. By examining the development of certain structures and cell types characteristic of quadrant-specific fates for each of these species, we have shown that isolated blastomeres of the indirect-developing nemertean, C. lacteus, are capable of generating cell fates that are not a consequence of that cell's normal developmental program. For instance, dorsal blastomeres can form muscle fibers when cultured in isolation. In contrast, isolated blastomeres of the direct-developing species, N. bivittata do not regulate their development to the same extent. Some cell fates are specified in a precocious manner in this species, such as those that give rise to the eyes. Thus, these findings indicate that equal-cleaving spiralian embryos can utilize different mechanisms of cell fate and axis specification. The implications of these patterns of nemertean development are discussed in relation to experimental work in other spiralian embryos, and a model is presented that accounts for possible evolutionary changes in cell lineage and the process of cell fate specification amongst these protostome phyla.

scholarly journals How embryos work: a comparative view of diverse modes of cell fate specification

Development ◽  
1990 ◽  
Vol 108 (3) ◽  
pp. 365-389 ◽  
Author(s):  
E.H. Davidson
Keyword(s):  
Cell Fate ◽  
Spatial Information ◽  
Cell Interaction ◽  
Cell Fate Specification ◽  
Embryonic Axes ◽  
Gastropod Mollusc ◽  
C Elegans ◽  
Molecular Interpretation ◽  
Gene Regulatory ◽  
Set Up

Embryonic processes in the nematode C. elegans, the gastropod mollusc Ilyanassa, the dipteran Drosophila, the echinoid Strongylocentrotus purpuratus, the ascidian Ciona, the anuran Xenopus, the teleost Brachydanio and mouse are compared with respect to a series of parameters such as invariant or variable cleavage, the means by which the embryonic axes are set up, egg anisotropies and reliance on conditional or on autonomous specification processes. A molecular interpretation of these modes of specification of cell fate in the embryo is proposed, in terms of spatial modifications of gene regulatory factors. On this basis, classically defined phenomena such as regulative development and cytoplasmic localization can be interpreted at a mechanistic level, and the enormous differences between different forms of embryogenesis in the Animal Kingdom can be considered within a common mechanistic framework. Differential spatial expression of histospecific genes is considered in terms of the structure of the gene regulatory network that will be required in embryos that utilize cell-cell interaction, autonomous vs conditional specification and maternal spatial information to differing extents. It is concluded that the regulatory architectures according to which the programs of gene expression are organized are special to each form of development, and that common regulatory principles are to be found only at lower levels, such as those at which the control regions of histospecific structural genes operate.

The nematode even-skipped homolog vab-7 regulates gonad and vulva position in Pristionchus pacificus

Development ◽  
2001 ◽  
Vol 128 (2) ◽  
pp. 253-261 ◽  
Author(s):  
B. Jungblut ◽  
R.J. Sommer
Keyword(s):  
Cell Fate ◽  
Cell Lineage ◽  
Nematode Species ◽  
Cellular Level ◽  
Precursor Cells ◽  
Developmental Competence ◽  
Pristionchus Pacificus ◽  
Posterior Displacement ◽  
Cell Ablation ◽  
The One

In free-living nematodes, developmental processes like the formation of the vulva, can be studied at a cellular level. Cell lineage and ablation studies have been carried out in various nematode species and multiple changes in vulval patterning have been identified. In Pristionchus pacificus, vulva formation differs from Caenorhabditis elegans with respect to several autonomous and conditional aspects of cell fate specification. To understand the molecular basis of these evolutionary changes, we have performed a genetic analysis of vulva formation in P. pacificus. Here, we describe two mutants where the vulva is shifted posteriorly, affecting which precursor cells will form vulval tissue in P. pacificus. Mutant animals show a concomitant posterior displacement of the gonadal anchor cell, indicating that the gonad and the vulva are affected in a similar way. We show that mutations in the even-skipped homolog of nematodes, vab-7, cause these posterior displacements. In addition, cell ablation studies in the vab-7 mutant indicate that the altered position of the gonad not only changes the cell fate pattern but also the developmental competence of vulval precursor cells. Investigation of Cel-vab-7 mutant animals showed a similar but weaker vulva defective phenotype to the one described for Ppa-vab-7.

A glial cell arises from an additional division within the mechanosensory lineage during development of the microchaete on the Drosophila notum

Development ◽  
1999 ◽  
Vol 126 (20) ◽  
pp. 4617-4622 ◽  
Author(s):  
G.V. Reddy ◽  
V. Rodrigues
Keyword(s):  
Glial Cell ◽  
Cell Fate ◽  
Cell Lineage ◽  
The Other ◽  
Sensory Cells ◽  
Cell Fate Specification ◽  
Fate Specification ◽  
Low Levels ◽  
Proposed Modification ◽  
Glial Marker

We have used different cell markers to trace the development of the sensory cells of the thoracic microchaete. Our results dictate a revision in the currently accepted model for cell lineage within the mechanosensory bristle. The sensory organ progenitor divides to form two secondary progenitors: PIIa and PIIb. PIIb divides first to give rise to a tertiary progenitor-PIII and a glial cell. This is followed by division of PIIa to form the shaft and socket cells as described before. PIII expresses high levels of Elav and low levels of Prospero and divides to produce neuron and sheath. Its sibling cell expresses low Elav and high Prospero and is recognized by the glial marker, Repo. This cell migrates away from the other cells of the lineage following differentiation. The proposed modification in lineage has important implications for previous studies on sibling cell fate choice and cell fate specification in sensory systems.

scholarly journals The autonomous cell fate specification of basal cell lineage: the initial round of cell fate specification occurs at the two-celled proembryo stage

2017 ◽  
Vol 91 (6) ◽  
pp. 1051-1063 ◽  
Author(s):  
Liang-Huan Qu ◽  
Xuemei Zhou ◽  
Xinbo Li ◽  
Shi-Sheng Li ◽  
Jing Zhao ◽  
...  
Keyword(s):  
Cell Fate ◽  
Basal Cell ◽  
Cell Lineage ◽  
Cell Fate Specification ◽  
Fate Specification

scholarly journals Faster, higher, stronger: timely and robust cell fate/identity commitment in stem cell lineages

Open Biology ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 180243 ◽  
Author(s):  
Kun Liu ◽  
Ke Xu ◽  
Yan Song
Keyword(s):  
Stem Cell ◽  
Cell Fate ◽  
Transcriptional Control ◽  
Cell Lineage ◽  
Cell Fate Specification ◽  
Developmental Abnormalities ◽  
Cell Lineages ◽  
Identity Commitment ◽  
Regulatory Strategies ◽  
Stem Cell Lineage

Precise specification of cell fate or identity within stem cell lineages is critical for ensuring correct stem cell lineage progression and tissue homeostasis. Failure to specify cell fate or identity in a timely and robust manner can result in developmental abnormalities and diseases such as cancer. However, the molecular basis of timely cell fate/identity specification is only beginning to be understood. In this review, we discuss key regulatory strategies employed in cell fate specification and highlight recent results revealing how timely and robust cell fate/identity commitment is achieved through transcriptional control.

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