Cell Lineage Analysis Research Articles

Cell cycles and clonal strings during formation of the zebrafish central nervous system.

Cell lineage analysis of central nervous system progenitors during gastrulation and early segmentation in the zebrafish reveals consistent coupling of specific morphogenetic behaviors with particular cell cycles. Cells in single clones divide very synchronously. Cell divisions become progressively oriented, and act synergistically with oriented intercalations during the interphases of zygotic cell cycles 15 and 16 to extend a single lineage into a long, discontinuous string of cells aligned with the nascent embryonic axis. Dorsalwards convergence brings the string to the midline and, once there, cells enter division 16. This division, or sometimes the next one, and the following cell movement reorient to separate siblings across the midline. This change converts the single string into a bilateral pair of strings, one forming a part of each side of the neural tube. The stereotyped cellular behaviors appear to account for the previously reported clonal restriction in cell fate and to underlie morphogenesis of a midline organ of proper length and bilateral shape. Regulation of cellular morphogenesis could be cell-cycle dependent.

INTRODUCTION: Cell lineage analysis in chemosensory research

INTRODUCTION: Cell lineage analysis in chemosensory research

Environmental signals and neural crest cells

Cell lineage analysis in both the central and peripheral nervous system of vertebrates has revealed that many neural progenitor cells are multipotent. These observations have raised the general issue of when and how such multipotent progenitors generate their various differentiated progeny. The environment of these progenitors controls the cell lineage decisions in the neural crest. This review considers the roles of the environmental signals in the context of the development of several different neural crest-derived lineages.

Cell-lineage analysis of the prototroch of the gastropod molluscPatella vulgata shows conditional specification of some trochoblasts.

Embryos of many spirally cleaving species possess a characteristic cell type, the trochoblasts. These cells differentiate early in development into ciliated cells and give rise to the prototroch, the locomotory organ of the trochophore larva. As a necessary prelude to the investigation of the mechanisms that are responsible for specification of trochoblasts in the equally cleaving gastropod molluscPatella vulgata, the cell-lineage of the prototroch was studied. This was done by microinjection of the cell-lineage tracer lucifer yellow-dextran in trochoblasts and by scanning electron microscopical analysis of formation of the prototroch. The results show that trochoblasts that form the prototroch are of different clonal origin and that the four quadrants of the embryo have an unequal contribution to the prototroch. Since the four quadrants of the equally cleaving embryo are initially equipotent, some trochoblasts must become conditionally specified. Other trochoblasts seem to become autonomously specified. After initial ciliation some trochoblasts become deciliated and for some cells the choice between a larval and an adult cell fate is conditionally specified. Cell-lineage analysis demonstrates that the various autonomously and conditionally specified trochoblasts are organised according to the dorsoventral axis of the embryo. Possible mechanisms that can account for the conditional specification of trochoblasts - including a role for the 3D macromere, which forms the primary mesoderm and is responsible for the formation of the dorsoventral axis of the embryo - are discussed.

Mosaic analysis of the embryonic origin of taste buds.

The embryonic origins of taste receptor cells have not been established experimentally. Although related receptor cells (e.g. hair cells of the inner ear, lateral line receptors) are known to arise from neurogenic ectoderm (e.g. neural crest or placodes), taste buds are described as arising from local epithelial cells. Also unknown is whether or not each taste bud is a clone of cells, i.e. arising from a single progenitor. To address these problems, mosaic and chimeric analyses of lingual epithelium and taste buds have been undertaken. This paper describes the theory of chimeric and mosaic cell lineage analyses, the advantages and disadvantages, and the preliminary results obtained from the examination of the taste buds and lingual epithelium of: 1) mosaic Xenopus, 2) chimeric mice and 3) X-inactivation mosaic mice.

Simple and efficient generation of marked clones in Drosophila.

Cell lineage analysis and mosaic analysis of mutations are important techniques that are used to study the development of many organisms. Unfortunately, the methods employed for such analyses are usually inefficient, technically demanding or labor intensive. In Drosophila, the most common methodology used for the generation of mosaic animals is mitotic recombination, which is induced by X-rays. Although this technique is simple, it has the undesirable characteristics of a low efficiency and a high rate of cell death. Furthermore, although a large number of marker systems has been employed to detect mitotic recombinants, none allows easy identification of clones for all cell types. A system is described here that allows a highly efficient generation of clones with the concomitant expression of an easily detectable cellular marker. This method can be applied to cell lineage and mosaic analysis in Drosophila. The site-specific yeast FLP recombinase, under the control of a heat shock-inducible promoter, efficiently catalyses mitotic recombination specifically at the site of a FLP recombination target (FRT). In this system, recombination fuses the alpha-tubulin promoter to the lacZ gene, allowing transcription of the marker. Recombinant cells and their progeny can, therefore, be detected by standard assays for beta-galactosidase. Of particular importance is the fact that only the cells of interest stain, thus allowing their simple detection in any tissue. We demonstrate that, by intermolecular recombination, we can use FLIP recombinase to generate marked clones efficiently in embryonic, larval and adult tissues. This simple and efficient technique is well suited to cell-lineage analysis and can be easily extended to the generation and detection of mutant clones in mosaic animals.

The design and synthesis of smart magnetic resonance imaging agents for embryonic cell lineage analysis.

The design and synthesis of smart magnetic resonance imaging agents for embryonic cell lineage analysis.

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

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).

Cell lineage analysis in neural crest ontogeny.

The neural crest is a transitory and pluripotent structure of the vertebrate embryo composed of cells endowed with developmentally regulated migratory properties. We review here a series of studies carried out both in vivo and in vitro on the ontogeny of the neural crest in the avian embryo. Through in vivo studies we established the fate map of the neural crest along the neuraxis prior to the onset of the migration and we demonstrated the crucial role played by the tissue environment in which the crest cells migrate in determining their fate. Moreover, the pathways of neural crest cell migration could also be traced by the quail-chick marker system and the use of the HNK1/NC1 monoclonal antibody (Mab). A large series of clonal cultures of isolated neural crest cells showed that, at migration time, most crest cells are pluripotent. Some, however, are already committed to a particular pathway of differentiation. The differentiation capacities of the pluripotent progenitors are highly variable from one to the other cell. Rare totipotent progenitors able to give rise to representatives of all the phenotypes (neuronal, glial, melanocytic, and mesectodermal) encountered in neural crest derivatives were also found. As a whole we propose a model according to which totipotent neural crest cells become progressively restricted (according to a stochastic rather than a sequentially ordered mechanism) in their potentialities, while they actively divide during the migration process. At the sites of gangliogenesis, selective forces allow only certain crest cells potentialities to be expressed in each type of peripheral nervous system (PNS) ganglia.

1105 Glial cell lineage analysis through detection of the gfap promoter activity

1105 Glial cell lineage analysis through detection of the gfap promoter activity

Medial edge epithelium fate traced by cell lineage analysis during epithelial-mesenchymal transformation in vivo

Vital cell labeling techniques were used to trace the fate of the medial edge epithelial (MEE) cells during palatal fusion in vivo. Mouse palatal tissues were labeled in utero with DiI. The fetuses continued to develop in utero and tissues of the secondary palate were examined at several later stages of palatal ontogeny. The presence and distribution of DiI was correlated with the presence of cell phenotype-specific markers. During the initial stages of palatal fusion the DiI-labeled MEE were present in the midline position. These cells were attached to an intact laminin-containing basement membrane and contained keratin intermediate filaments. At later stages of palatogenesis the DiI-labeled MEE were not separated from the mesenchyme by an intact basement membrane and did not contain keratin. In late fetal development, DiI-labeled cells without an epithelial morphology were present in the mesenchyme. The transition of the DiI-labeled cells from an epithelial phenotype to a mesenchymal phenotype is consistent with a fate of epithelial-mesenchymal transformation rather than programmed cell death.

In vivo analysis of cell lineage in vertebrate neurogenesis

One of the key processes in building the nervous system is the assignment of cell phenotype. Experiments in culture and in some amenable organisms have provided evidence for a wide variety of developmental strategies that generate the diverse phenotypes in the mature nervous system. These range from a strict, autonomous control of cell fate in which the precursors dictate the phenotype(s) of their progeny, to a much looser, conditional scheme in which interactions of the cells with their environment play a major role in their selection of phenotype. A first step towards analyzing the control of cell fate is to define the set of phenotypes to which a single precursor can give rise. Although this goal sounds simple, meeting this challenge has been difficult because many of the key events take place in large, apparently homogeneous populations of cells. To circumvent this problem, recent experimental designs have utilized techniques to make individual cells distinct from one another, making it possible to follow single precursor cells and their progeny unambiguously over time. Either integration of a marker gene by a retrovirus or microinjection of a vital dye with a micropipette render a precursor uniquely identifiable; because these markers are inherited by its descendants at mitosis, such approaches make the family tree of one precursor discernable from the mass of other unlabelled cells. Although none of the techniques is free from flaws, they are generating useful data on cell lineages and movements during neuronal development. The results collected to date suggest that there is no single developmental program that is common to all systems; instead, a blend of different developmental strategies are utilized in different regions of the developing nervous system.

Role of ultrastructural studies in the analysis of cell lineage in the mammalian pre-implantation embryo.

Ultrastructural studies have contributed significantly to our understanding of cell lineage differentiation in the mammalian pre-implantation embryo. Such studies have documented, and continue to document, morphological, biochemical, and physiological characteristics of the cell lineages established during the pre-implantation period in eutherian embryos, principally that of the mouse. This review evaluates these contributions and identifies areas of study in which ultrastructural analysis is most likely to have an important role in the future.

Cell adhesion, cell separation and plant morphogenesis

A simplified and useful view of plant cell development is that it involves the spatial and temporal organization of cell division, cell expansion and cell differentiation all taking place within the constraints of a lack of cell migration. A facet of such development that has often been neglected, is understanding how the cells of a developing structure hold fast or adhere. Subsequently in development the adhered cells of apices or embryos give rise to more loosely attached cells in mature structures where the degree of cell separation and intercellular space formation is developmentally regulated. Recent cell biological studies, most significantly in the derivation of monoclonal antibody probes forthe plant cell surface (Knox, 1992; Roberts, 1990), have increased our awareness of the local modifications of cell walls and rekindled interest in aspects of plant cell wall adhesion and intercellular space formation. It seems timely to examine our current understanding of the mechanisms of cell adhesion and separation and their importance for plant morphogenesis. Molecular probes for cell surface components offer immense potential, not only for the specific study of the local wall modifications such as those resulting in cell separation but also as probes of molecular markers of cell identity relating to position and context. This essay attempts to draw some of the threads together regarding both the nature and importance of cell adhesion and cell separation in plant tissues.

Clonal analysis of glial cell lineage

The effects of various cytokines on survival and differentiation of an astrocyte progenitor cell line (AP-16) were examined. Epidermal growth factor (EGF) deprivation caused death of AP-16 cells by apoptosis. Transforming growth factor-α (TGF-α) and basic fibroblast growth factor (bFGF) prevented the apoptosis occurring in the absence of EGF. Leukemia inhibitory factor (LIF) and ciliary neurotrophic factor (CNTF) induced glial fibrillary acidic protein (GFAP) and decreased A2B5 antigen in AP-16 cells, indicating that these cytokines induced AP-16 cells to differentiate into astrocytes.

6 Experimental Chimeras: Current Concepts and Controversies in Normal Development and Pathogenesis

Chimeras having distinguishable cell lineages are useful in the study of cell fate, cell–cell interaction in embryonic development, organ maintenance, and pathogenesis of diseases. The action of specific developmental mutations has been examined by rescuing mutations in chimeras. The resulting animals can establish whether the genetic effects of these mutations are cell dependent or cell autonomous. Mosaic patterns are both conserved and regulated in visceral organs so that the mosaic pattern analysis provides information useful in the generation of hypotheses of cell division patterns during organ formation. Mosaic pattern analysis in chimeras provides valuable cues to tissue organization. The development of new molecular markers, useful in prospective cell lineage analysis, provides new approaches to understanding the cell commitment and fate in mammalian development.

Analysis of Cell Lineage in the Rat Cerebral Cortexa

Analysis of Cell Lineage in the Rat Cerebral Cortex^a

Shoot initiation on a Graptopetalum leaf: sequential scanning electron microscopic analysis for epidermal division patterns and quantitation of surface growth (kinematics)

A non destructive mold and cast procedure allows repeated imaging of growing plant surfaces by scanning electron microscopy. Individual cells and their clonal progeny can be recognized in succesive images. This allows comprehensive analysis of cell lineage on the epidermis. It also provides data for the quantitative characterization of surface growth (kinematics). The technique and both types of analysis were applied to a small meristematic surface of a Graptopetalum leaf as it develops from a flat field of parallel cell files into a stem and leaves, all with radial symmetry. New organ surfaces formed from groups of cells that were not clones of the cells initially present. Hence cell image was not important. In the revision of symmetry some regions retain the original cell file polarity, others change it by 90°. Areas that do not change have mainly transverse anticlinal divisions. Areas that change maximally show repeated longitudinal divisions to make a rib meristem pattern with new cross walls normal to the direction of future growth. Growth direction soon changes. This occurs in regions known to undergo a 90° shift in cellulose reinforcement direction. It is concluded that distinctive anticlinal division behavior accompanies lateral formation and may be significant in the mechanism. Key words: anticlinal divisions, Graptopetalum, kinematics, morphogenesis, shoot initiation, sequential scanning electron microscopy.

Clonal analysis of astrocyte diversity in neonatal rat spinal cord cultures

Within the mammalian CNS, astrocytes appear to be a heterogeneous class of cells. To assay the number of distinct types of astrocytes in the rat spinal cord, cell lineage and phenotypic analyses were carried out on cultures from newborn rat spinal cord and five distinct types of astrocytes were observed. Proliferating precursors for each class of astrocyte were isolated by low density culture and shown to give rise to 5 distinct and morphologically homogeneous clusters of GFAP + astrocytes. Immunocytochemical analysis with antibodies A2B5 and Ran-2, which identify different glial lineages in optic nerve cultures, demonstrated that many clusters included both A2B5+ and A2B5- cells. Similarly, many clusters also possessed a mixture of Ran-2+ and Ran-2-cells, suggesting that in spinal cord cultures, in contrast to optic nerve cultures, expression of these antigens is regulated by individual cells rather than by cell lineage. Single-cell cloning studies, revealed that the abundance and proliferative capacity of individual astrocyte precursors differed depending on the type of astrocyte. To assay the effects of a complex cellular environment on the composition of astrocyte clones, lineage analysis was performed in complete spinal cord cultures using a replication deficient retrovirus. Although similar morphologically homogeneous clones of cells to those seen with single-cell clones were observed, the proliferative capacity and relative abundance of the distinct astrocyte precursors differed from that seen in single-cell cloning studies. Together these observations suggest that in spinal cord, gliogenesis is considerably more complex than in the optic nerve and that cultures of newborn rat spinal cord contain multiple, distinct populations of astrocytes.

Cell type specification during sea urchin development

Recent discoveries indicate that cell lineages and fates play a key role in the establishment of spatially restricted gene expression during sea urchin development. Unique sets of founder cells generate five territories of gene expression by means of an invariant pattern of complete cleavage. Cell lineage analysis demonstrates that the second embryonic axis, the oral-aboral axis, is specified with reference to the first cleavage plane. In the undisturbed embryo, clones that contribute to one territory or another begin to appear at the third cleavage, and founder cell segregation to all five territories is completed by the sixth cleavage. Founder cell segregation is a key feature of mechanisms that establish the spatially defined gene activity of sea urchin embryogenesis.