Cell lineage analysis of the expression of an engrailed homolog in leech embryos

Development ◽  
1993 ◽  
Vol 117 (3) ◽  
pp. 857-871 ◽  
Author(s):  
D. Lans ◽  
C.J. Wedeen ◽  
D.A. Weisblat
Keyword(s):  
Early Development ◽  
Body Wall ◽  
Cell Clone ◽  
Cell Lineage ◽  
Blast Cell ◽  
Posterior Portion ◽  
Primary Blast ◽  
Development Stages ◽  
Cell Clones ◽  
Lineage Analysis

ht-en is an engrailed-class gene that is expressed during early development and neurogenesis in embryos of the leech Helobdella triserialis. During the early development of this annelid (stages 7–9), ht-en is expressed in each of the ectodermal and mesodermal teloblast lineages that contributes progeny to the definitive segments. ht-en is expressed transiently by individually identified cells within the segmentally iterated primary blast cell clones. Its expression is correlated with the age of the primary blast cell clone. After consegmental primary blast cell clones from the different teloblast lineages have come into segmental register, cells that express ht-en during stages 7–9 are clearly confined to a transverse region corresponding to the posterior portion of the segmental anlage, but not all cells within this region express ht-en. Only a minority of the identified cells that express ht-en during terminal differentiation of the segmental ganglia and body wall (stages 10–11) are descendants of cells that express ht-en in early development (stages 7–9).

Developmental origin of segmental identity in the leech mesoderm

Development ◽  
1993 ◽  
Vol 117 (1) ◽  
pp. 177-189 ◽  
Author(s):  
L. Gleizer ◽  
G.S. Stent
Keyword(s):  
Cell Clone ◽  
Cell Lineage ◽  
Blast Cell ◽  
The Other ◽  
Longitudinal Body Axis ◽  
Cell Clones ◽  
Intrinsic Mechanism ◽  
Blast Cells ◽  
A Cell ◽  
Segmental Identity

Segmentation in the leech embryo is established by a stereotyped cell lineage. Each of the 32 segments arises from homologous, bilaterally symmetrical complements of mesodermal and ectodermal blast cell clones. Although segments are homologous, they are regionally differentiated along the longitudinal body axis. Various segments display idiosyncratic ensembles of features, which constitute discrete segmental identities. The differentiation of segment-specific features, such as the mesoderm-derived nephridia, genital primordia and identified Small Cardioactive Peptide immunoreactive neurons, reflects a diversification of the developmental fates of homologous blast cell clones. We have investigated whether segment-specific differentiation of homologous mesodermal blast cell clones depends on cell-intrinsic mechanisms (based on the cells' lineage history) or on cell-extrinsic mechanisms (based on the cells' interactions with their environment) in embryos of Theromyzon rude. For this purpose, we first mapped the segment-specific fates of individual mesodermal blast cell clones, and then induced mesodermal clones to take part in the formation of segments for which they are not normally destined. Two types of ectopic segmental position were produced: one in which a mesodermal blast cell clone was out of register with all other consegmental cells and one in which a mesodermal blast cell clone was out of register with its overlying ectoderm, but was in normal register with the mesoderm and ectoderm on the other side of the embryo. Mesodermal blast cell clones that developed in either type of ectopic segmental position gave rise to segment-specific features characteristic of their original segmental fates rather than their ectopic positions. Thus, the development of segmental identity in the leech mesoderm is attributable to a cell-intrinsic mechanism and, either before or soon after their birth, mesodermal blast cells are autonomously committed to segment-specific fates.

Establishment of segment polarity in the ectoderm of the leech Helobdella

Development ◽  
2001 ◽  
Vol 128 (9) ◽  
pp. 1629-1641
Author(s):  
E.C. Seaver ◽  
M. Shankland
Keyword(s):  
Single Cells ◽  
Embryonic Stem ◽  
Blast Cell ◽  
Drosophila Embryo ◽  
Detectable Effect ◽  
Primary Blast ◽  
Anteroposterior Axis ◽  
Developmental Fate ◽  
Cell Clones ◽  
Segment Polarity

The segmented ectoderm and mesoderm of the leech arise via a stereotyped cell lineage from embryonic stem cells called teloblasts. Each teloblast gives rise to a column of primary blast cell daughters, and the blast cells generate descendant clones that serve as the segmental repeats of their particular teloblast lineage. We have examined the mechanism by which the leech primary blast cell clones acquire segment polarity - i.e. a fixed sequence of positional values ordered along the anteroposterior axis of the segmental repeat. In the O and P teloblast lineages, the earliest divisions of the primary blast cell segregate anterior and posterior cell fates along the anteroposterior axis. Using a laser microbeam, we ablated single cells from both o and p blast cell clones at stages when the clone was two to four cells in length. The developmental fate of the remaining cells was characterized with rhodamine-dextran lineage tracer. Twelve different progeny cells were ablated, and in every case the ablation eliminated the normal descendants of the ablated cell while having little or no detectable effect on the developmental fate of the remaining cells. This included experiments in which we specifically ablated those blast cell progeny that are known to express the engrailed gene, or their lineal precursors. These findings confirm and extend a previous study by showing that the establishment of segment polarity in the leech ectoderm is largely independent of cell interactions conveyed along the anteroposterior axis. Both intercellular signaling and engrailed expression play an important role in the segment polarity specification of the Drosophila embryo, and our findings suggest that there may be little or no conservation of this developmental mechanism between those two organisms.

Cell lineage and segmentation in the leech

1985 ◽  
Vol 312 (1153) ◽  
pp. 39-56 ◽  
Keyword(s):  
Stem Cells ◽  
Embryonic Stem Cells ◽  
Cell Lines ◽  
Embryonic Stem ◽  
Cell Lineage ◽  
Blast Cell ◽  
Cell Clones ◽  
Cell Patterns ◽  
Blast Cells ◽  
Precise Relationship

Segments in the leech arise by the proliferation of longitudinally arrayed bandlets of blast cells derived from ten identifiable embryonic stem cells, two M, two N, four O /P and two Q teloblasts. In each bandlet, older blast cells lie ahead of those born later. By using microinjected cell lineage tracers it was shown previously that the teloblasts give rise to characteristic cell patterns made up of segmentally iterated complements of progeny designated as M, N, O, P and Q kinship groups. When a teloblast is injected after it has begun generating blast cells, a boundary is observed later in development between anterior, unlabelled progeny of blast cells produced before injection and posterior, labelled progeny of blast cells produced after injection. We have examined such boundaries in detail to establish the precise relationship between blast cell clones and segments, with the following conclusions: (i) in the M, O and P cell lines, one blast cell generates one segmental complement of progeny, but serially homologous blast clones intermix so that no segment boundaries can be defined based on primary blast cell clones; (ii) in the N and Q cell lines, two blast cells are required to generate a complete segmental complement of progeny; (iii) in the process of forming the germinal plate, cells derived from the N and Q teloblasts move past those derived from the M and O /P teloblasts, so that consegmental blast cell clones do not come into register until well after the establishment of segmentally iterated units within each bandlet.

Major sex-determining genes and the control of sexual dimorphism in Caenorhabditis elegans

Genome ◽  
1989 ◽  
Vol 31 (2) ◽  
pp. 625-637 ◽  
Author(s):  
Jonathan Hodgkin ◽  
Andrew D. Chisholm ◽  
Michael M. Shen
Keyword(s):  
Caenorhabditis Elegans ◽  
Sex Determination ◽  
X Chromosome ◽  
Germ Line ◽  
Cell Lineage ◽  
Regulatory Genes ◽  
Nematode Caenorhabditis Elegans ◽  
X Chromosomes ◽  
The Many ◽  
Lineage Analysis

Sex determination in Caenorhabditis elegans involves a cascade of major regulatory genes connecting the primary sex determining signal, X chromosome dosage, to key switch genes, which in turn direct development along either male or female pathways. Animals with one X chromosome (XO) are male, while animals with two X chromosomes (XX) are hermaphrodite: hermaphrodite development occurs because the action of the regulatory genes is modified in the germ line so that both sperm and oocytes are made inside a completely female soma. The regulatory genes are being examined by both genetic and molecular means. We discuss how these major genes, in particular the last switch gene in the cascade, tra-1, might regulate the many different sex-specific events that occur during the development of the hermaphrodite and of the male.Key words: nematode, Caenorhabditis elegans, sex determination, sexual differentiation, cell lineage analysis.

Assignment of human natural killer (NK)-like cells to the T cell lineage. Single allospecific T cell clones lyse specific or NK-sensitive target cells via distinct recognition structures

1984 ◽  
Vol 14 (2) ◽  
pp. 121-125 ◽  
Author(s):  
Alessandro Moretta ◽  
Giuseppe Pantaleo ◽  
Maria Cristina Mingari ◽  
Giovanni Melioli ◽  
Lorenzo Moretta ◽  
...  
Keyword(s):  
T Cell ◽  
Natural Killer ◽  
Cell Lineage ◽  
Target Cells ◽  
T Cell Clones ◽  
Cell Clones

Cell lineage of homeotic mutants of Drosophila

1985 ◽  
Vol 312 (1153) ◽  
pp. 139-144 ◽  
Keyword(s):  
Mode Of Action ◽  
Cell Lineage ◽  
Precursor Cells ◽  
Larval Period ◽  
Homeotic Genes ◽  
Lineage Analysis

The homeotic genes specify the development of specific groups of precursor cells. They establish the correct state of determination of the different primordia. Cell lineage analysis has been particularly useful in studying the mode of action of homeotic genes. The main findings are: (i) most, perhaps all, the homeotic genes are required by every cell of the corresponding primordium (that is, they are cell autonomous); (ii) they act on anatomical units defined by compartment boundaries and including one or more compartments, (iii) most, but not all, homeotic genes are required until the end of the larval period; (iv) the homeotic genes act in combination so that the appropriate development of a given primordium may be established by the contribution of several homeotic genes.

Cell lineage analysis in neural crest ontogeny

1993 ◽  
Vol 24 (2) ◽  
pp. 146-161 ◽  
Author(s):  
Nicole M. Le Douarin ◽  
Elisabeth Dupin
Keyword(s):  
Neural Crest ◽  
Cell Lineage ◽  
Lineage Analysis

Genetic analysis of leaf development in cotton

Development ◽  
1991 ◽  
Vol 113 (Supplement_1) ◽  
pp. 39-46 ◽  
Author(s):  
Liam Dolan ◽  
R. Scott Poethig
Keyword(s):  
Leaf Growth ◽  
Leaf Shape ◽  
Cell Lineage ◽  
Cotton Leaf ◽  
Expansion Phase ◽  
Genetic Mosaics ◽  
Developmental Age ◽  
Allometric Analysis ◽  
Marginal Region ◽  
Lineage Analysis

Leaf shape in cotton is regulated by the developmental age of the shoot and by several major genes that affect leaf lobing. The effect of these factors was investigated by allometric analysis, cell lineage analysis, and by studying the expression of the leaf shape mutation, Okra, in genetic mosaics. Allometric analysis of leaf growth suggests that leaf shape is determined during the initiation of the primordium rather than during the expansion phase of leaf growth. Clonal analysis demonstrates that both the rate and duration of cell division are fairly uniform throughout the leaf. Cells in the marginal region of the developing cotton leaf contribute more to the growth of the lamina than they do in tobacco. The Okra mutation acts early in the development of a leaf and appears to accentuate a developmental pattern that is also responsible for heteroblastic variation in leaf shape. The expression of this mutation in genetic mosaics demonstrates that its effect does not diffuse laterally within the leaf primordium.

Cell lineage analysis of Schwann cells in the PNS determined by shiverer-normal mouse chimeras

1984 ◽  
Vol 105 (1) ◽  
pp. 221-226 ◽  
Author(s):  
Katsuhiko Mikoshiba ◽  
Minesuke Yokoyama ◽  
Ken Takamatsu ◽  
Yasuzo Tsukada ◽  
Tatsuji Nomura
Keyword(s):  
Schwann Cells ◽  
Normal Mouse ◽  
Cell Lineage ◽  
Mouse Chimeras ◽  
Lineage Analysis
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