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At least 307 records · Page 17Linked to original sources
PubMed1992

CFU-rAM, the origin of lung macrophages, and the macrophage lineage.

Macrophage precursors and their progeny have been identified in early rat embryos with the use of a peroxidase-coupled marker, isolectin B4 of Griffonia simplicifolia (GSA I-B4). The macrophage lineage can be traced back to actively dividing GSA-positive angular cells present in the mesenchyme of late neurulas. These increase in number and establish residence successively in rudiments of the central nervous system, liver, and lungs. In organ-cultured fetal lungs they transform directly into a self-replicating population of macrophages responsive to colony-stimulating factors. The angular cell therefore can be seen as the source of lung macrophages during prenatal life. The extent to which this manner of production continues in postnatal life is unclear, but it appears that central hematopoietic tissues (bone marrow, spleen) may generate macrophages by a direct pathway from early-committed progenitors as well as indirectly through a series of intermediate stem cells. Considering the wealth of new information available from diverse studies in specialized culture environments and to a lesser extent from studies in vivo, it is time to integrate these findings into a more comprehensive theory of macrophage origin and fate than we have at present.

Animals↗
PubMed2001

Application of bone marrow-derived stem cells in experimental nephrology.

Recent advancement in developmental biology has led to the discovery of immature mesenchymal stem cells in bone marrow and several established organs. The therapeutic potentials of such stem cells for treating serious diseases constitute a major rationale for every research effort, and clinical trials for replacing some damaged tissues such as cartilage are currently under way. Although the feasibility of such stem cell therapies for renal diseases remains unknown, it is worthy of pursuing possibilities. As an experimental tool, we have made chimeric rats that carry the bone marrow of transgenic rats expressing green fluorescent protein (GFP) throughout the body. All marrow lineages can be traced with bright green fluorescence regardless of their terminal phenotypes in chimeric rats. When compared with other conventional strategies for tracking bone marrow-derived cells, our system is highly sensitive and allows us to take advantage of the rat nephrology. Using this system, we have reported that bone marrow provides mesangial cells during repair process. In this manuscript, we briefly summarize our experiences.

Animals↗
PubMed1987

Cytoplasmic genetic effects on preweaning growth and milk yield in Hereford cattle.

Performance records on Hereford cattle raised in two herds were used to evaluate cytoplasmic genetic effects on preweaning growth and milk production. Animals were traced through maternal lineage to foundation females to form cytoplasmic lines. Growth records were available on 1,189 calves at Raleigh and 1,599 at Plymouth representing 27 and 15 cytoplasmic lines, respectively. Milk records were available on 418 cows at Raleigh and 522 cows at Plymouth, representing 20 and 13 cytoplasmic lines. After adjustment for sire, cytoplasmic effects were significant for birth weight (BWT), average daily gain (ADG) and 205-d weight (WT205) in both herds. Cytoplasm accounted for 2, 5 and 5% of the variance for BWT, ADG and WT205 at Raleigh; and 1, 2 and 2% of the variance at Plymouth. After addition of maternal grandsire to the model, cytoplasm was still significant; however, variances were reduced at Plymouth. Cytoplasmic effects for milk yield were important at Raleigh (P less than .01) but marginal at Plymouth (P = .10). Variance components for cytoplasm accounted for 4 and 1% of the variance for milk yield at Raleigh and Plymouth, respectively. Ranges for least-squares constants for cytoplasmic lines corresponded to one of two standard deviations. Correlations among least-squares constants for ADG, WT205 and milk yield were high, suggesting that cytoplasmic effects were mediated through milk production. More research is needed to confirm these results before cytoplasmic inheritance is considered in breeding programs for beef cattle.

Animals↗
PubMed1989

C. Walton Lillehei and his trainees: one man's legacy to cardiothoracic surgery.

Between 1951 and 1967, Dr. C. Walton Lillehei trained 134 cardiothoracic surgeons at the University of Minnesota Hospital. Between 1967 and 1979, he trained another 20 surgeons at the New York Hospital-Cornell Medical Center. Twenty-three of these 154 Lillehei trainees became program directors of cardiothoracic programs and in turn trained 477 additional surgeons. Twenty-one of these second-generation trainees became program directors and trained 164 surgeons. Two of these third-generation trainees have become directors and have in turn trained 25 additional trainees. A total of at least 820 cardiothoracic surgeons, currently residing in 36 countries, can trace their preceptor lineage back to Dr. Lillehei. A number of significant clinical and research contributions have been forthcoming from these Lillehei trainees during the past 35 years.

Cardiac Surgical Procedures↗
PubMed1998

Developmental homologues: lineages and analysis.

Developmental processes present several problems for identifying homologies and analyzing their evolution. Most evolutionary techniques approach homologies from either a taxonomic or a molecular perspective. Approaches that can accommodate many problems of developmental evolution are not well developed. Developmental process and evolutionary lineage complexity lead to a number of largely unappreciated conceptual and analytic problems. Developmental processes can evolve by duplication or diversification. Each process is in a hierarchy of super- and subprocesses. As they evolve, process components may be exchanged with or acquired by those of other processes. Because they do not fit into standard analytic procedures, these situations (including reticulate or reticulate-appearing lineages, partial homologues, iterative features, and the tracing of nontaxonomic and nonmolecular evolutionary lineages) are often ignored or considered illegitimate. Biology's disdain for the dichotomously branching phylogenetic lineages that are the basis of standard analytic approaches is ignored at the risk of making falsely negative homology evaluations. I will present an approach that can accommodate analyses of these situations. The use of nontaxonomic and nonmolecular lineages provides a way to structure comparisons between other entities, as taxonomic lineages structure comparisons among potential homologues. From an informational point of view, any entity (either a structure or process) with an evolutionary history is a potential homologue with a potential evolutionary lineage. Comparing lineages of interacting entities can reveal topological incongruences among them. Methods that identify reticulated taxonomic and molecular lineages should also apply to other lineages. Partial homologues, resulting from reticulated lineages, can be handled in several possible ways. Analytically, such an entity can be treated as a partial homologue, a novel feature, an independent sub-unit, or a unitary feature homologous to the major contributor of its inherited features.

Animals↗
PubMed2006

Somite-derived cells replace ventral aortic hemangioblasts and provide aortic smooth muscle cells of the trunk.

We have previously shown that endothelial cells of the aortic floor give rise to hematopoietic cells, revealing the existence of an aortic hemangioblast. It has been proposed that the restriction of hematopoiesis to the aortic floor is based on the existence of two different and complementary endothelial lineages that form the vessel: one originating from the somite would contribute to the roof and sides, another from the splanchnopleura would contribute to the floor. Using quail/chick orthotopic transplantations of paraxial mesoderm, we have traced the distribution of somite-derived endothelial cells during aortic hematopoiesis. We show that the aortic endothelium undergoes two successive waves of remodeling by somitic cells: one when the aortae are still paired, during which the initial roof and sides of the vessels are renewed; and a second, associated to aortic hematopoiesis, in which the hemogenic floor is replaced by somite endothelial cells. This floor thus appears as a temporary structure, spent out and replaced. In addition, the somite contributes to smooth muscle cells of the aorta. In vivo lineage tracing experiments with non-replicative retroviral vectors showed that endothelial cells do not give rise to smooth muscle cells. However, in vitro, purified endothelial cells acquire smooth muscle cells characteristics. Taken together, these data point to the crucial role of the somite in shaping the aorta and also give an explanation for the short life of aortic hematopoiesis.

Animals↗
PubMed1997

Estimation of variance of maternal lineage effects among Canadian Holsteins.

Bayesian posterior estimates of variances of maternal lineage effects were obtained with a procedure that used Gibbs sampling. Data were records of yield during first parity from 245,510 Holstein cows that calved in Canada between 1990 and 1994. Maternal lineages were defined by tracing the maternal ancestry of cows to common female ancestors. Traits were standardized yields of milk, fat, and protein and percentages of fat and protein. Estimates of maternal lineage variance were < 0.5% of the total variance for all traits. Effects of this size hardly affected the cow rankings for estimated breeding value. Another analysis defined maternal lineages by establishing groups of dams and their daughters in an attempt to maximize the variance of environmental effects associated with maternal lineages, but only 1.1% of the variance in milk yield was associated with effects of the dam and daughter groups. Analyses of simulated data indicated that positive estimates of maternal lineage effects were not a result of restriction of estimates to positive values and that estimates of maternal lineage variance were biased slightly downward because of incomplete pedigree information. The partitioning of maternal lineage and additive genetic variance was correct when pedigree information was complete, according to results from simulation.

Animals↗
PubMed1996

Relationships between polymorphism for mitochondrial deoxyribonucleic acid and yield traits of Holstein cows.

Two independent data files from the breeding herd of Iowa State University and six North Carolina herds were used to examine relationships between yield traits and mtDNA polymorphism. Maternal lineages were established by tracing ancestry of cows to founder females in the herd book of the Holstein Association. Data from Iowa State University were 1476 records from 602 cows from 29 maternal lineages. The nucleotides of mtDNA encoding rRNA were sequenced. Eleven sites of polymorphism were found. An animal model for gene substitution was used to examine the relationship between sequence differences and yield traits. Traits analyzed were mature equivalent yield of milk, fat, SNF, and milk energy as well as concentrations of fat, SNF, and milk energy. Effects of sequence differences were significant for most traits. Sequence information from the D-loop was available for 12 lineages from North Carolina. The effect of polymorphism at 4 sites was examined using 1472 records from 668 cows. Traits measured were the same, except that protein replaced SNF. No significant relationships existed between any of the traits and D-loop polymorphism, but results suggested that an association might exist between polymorphism and concentrations of milk yield, fat percentage, and energy. Whenever a significant relationship was detected, the effect of mutation (rare genotype) was detrimental.

Animals↗
PubMed2006

The multiple dorsoventral origins and migratory pathway of tectal oligodendrocytes in the developing chick.

Oligodendrocytes have been considered to originate in a restricted ventricular zone of the ventral neural tube and to migrate and mature in their final targets. However, recent studies indicate that oligodendrocytes arise from multiple distinct dorsoventral origins. In this study, we investigate oligodendrocyte lineage cells in the embryonic optic tectum of chick, which develops from the dorsal region of the neural tube and invasion of optic tract. Oligodendrocyte precursor cells (OPCs) first appeared bilaterally on either side of the floor plate at E5. With further development, OPCs increased and spread laterally and dorsally to populate the optic tectum. At E7, OPCs appeared in another site along the ventral midline of the third ventricle, just dorsal to the optic chiasm. To examine the migration routes of these ventrally derived OPCs, we used DiI tracing in the organic culture and retinal denervation. Our results reveal that OPCs dispersed bilaterally along the optic tract and then migrated to the optic tectum in the stratum opticum (SO). In addition to these extrinsic OPCs, OPCs intrinsic to the tectal ventricle zone were identified at E14 using a combination of immunohistochemistry and retroviral mediated lineage tracing studies. These data support stage-specific dorsoventral origins and distribution of oligodendrocytes populating the optic tectum.

Age Factors↗
PubMed1988

Cell lineage analysis of lens epithelial cells induced to differentiate into fibres.

In explant cultures, lens epithelial cells grown in unsupplemented medium retain a morphology and packing arrangement similar to that found in the lens in vivo. In this culture system the epithelial cells can be induced to differentiate into fibres by the addition of retina conditioned medium (RCM). RCM also stimulates cell division. In order to trace the fibre cell lineage and to examine the relationship between cell division and fibre differentiation, single epithelial cells in explants from neonatal rat lenses were labelled with fluorescein-isothiocyanate-dextran. Explants were sub-divided into nine squares and one cell per square was injected with fluorescent label via a microcapillary. By marking the positions of labelled cells at 24-hr intervals for 6 days it was shown that most of the epithelial cells moved laterally within the explant. On average, cells in control explants moved about 20 microns day-1. Cells did not move in any particular direction within the explants and often changed direction. RCM stimulated a dramatic increase in migratory activity. There was about a four-fold increase in migratory activity in the first 24-hr interval, then, even with continued exposure to RCM, this activity quickly dropped over the next 2 days to the same levels as found in controls. As in controls, the cells moved in no particular direction and often changed direction. The observation that RCM stimulates cell migration in this explant system raises the possibility of an important role for active cell migration in the lens in situ. After 6 days culture the dimensions of labelled cells were measured using an image analyser. The areas of cells in controls fell within a narrow range from about 60- to 200 microns2. In contrast, explants grown in RCM had a wide range of cell areas from about 120- to 1500 microns2 and a large proportion of the cells showed some degree of elongation. In explants grown in RCM, 27.3% of labelled cells divided and half of these divisions were during the first 24 hr of culture. Overall there were about 9% more divisions recorded in RCM-treated than in control explants. An analysis of sizes of cells after 6 days of culture showed that whether or not cells divided after addition of RCM they showed very similar frequencies of cell sizes. Therefore, proliferating cells in the explants appear to be as capable of elongating and differentiating into fibres as the non-proliferating cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2004

Teleost fish genomes contain a diverse array of L1 retrotransposon lineages that exhibit a low copy number and high rate of turnover.

Retrotransposable elements exhibit a wide range of variation in population dynamics, abundance, and lineage diversity among host genomes across taxa. This range of diversity is illustrated by a single well-defined constituent monophyletic clade of L1 non-LTR retrotransposons that is shared between mammalian and teleost fish genomes. Despite the clear phylogenetic relationships that exist between mammalian and teleost L1 sequences, these elements exhibit markedly different dynamics within their respective taxa. While mammalian genomes typically contain a single, abundant lineage of L1 elements that traces millions of years of evolution, the zebraflsh genome was recently shown to exhibit a high diversity of ancient lineages coexisting at a very low copy number and apparently exhibiting a high rate of turnover. In the present study, a combination of degenerate PCR, lineage-specific PCR, and genomic Southern blot analysis is utilized to demonstrate high L1 lineage diversity, low copy number, and a high proportion of polymorphic inserts in the genomes of the killifish species, Fundulus heteroclitus. Additional species surveyed by degenerate PCR include Cyprinodon variegatus, Rivulus marmoratus, and Menidia beryllina. These results further support the generality of the differences that exist in host-element dynamics between teleost fish and mammalian genomes with regard to L1 retrotransposons.

Animals↗
PubMed1999

Antibodies directed against the chicken type II TGFbeta receptor identify endothelial cells in the developing chicken and quail.

Due to the availability of the endothelial cell marker QH1, experiments using quail embryos have traditionally been used to trace the endothelial cell lineage and describe the morphologic events of vessel formation. A comparable marker in the chicken has not been available. Here we report that antibodies raised against the extracellular domain of the chicken type II TGFbeta receptor (TBRII) preferentially identify endothelial cells in the chick. Endothelial cells can first be identified in the 6-somite chick embryo by TBRII expression. TBRII expression in 12- and 22-somite chick and quail embryos was found to directly correlate with the endothelial QH1 staining pattern in quail. This preferential labeling of endothelial cells persists until at least embryonic day 10 in the chick. These data indicate that antibodies to TBRII are an effective marker of endothelial cells in chick and provide useful reagents for the evaluation of vascular patterning.

Animals↗
PubMed1996

Hematopoietic stem cells in the mouse embryonic yolk sac.

The yolk sac is the first site of hematopoiesis during mammalian development. The yolk sac is also the first site of blood vessel development. Development of the blood islands in the yolk sac is an integrated process in which these two developmental events, hematopoiesis and vasculogenesis, proceed in concert. This review focuses on mouse yolk sac hematopoietic stem cells (YS-HSC), describing their differentiation in vitro and in vivo. YS-HSC go through a progressive series of changes prior to the initiation of lineage-specific differentiation. Experiments tracing their origins from postulated hemangioblasts, and the subsequent interaction between these stem cells and yolk sac endothelial cells are described. Differences between the extraembryonic YS-HSC and HSC found later within the embryo, perinatally or in adults, are described. YS-HSC have greater reproductive capability than HSC obtained from fetal liver, umbilical cord blood or adult bone marrow; they do not yet express major histocompatibility complex-associated antigens and they are able to reconstitute adult immunocompromised animals even when introduced in small numbers (< 100 cells/mouse). With recent results demonstrating the feasibility of expanding YS-HSC in vitro as well as of introducing new genes into these cells by transfection, the YS-HSC shows promise both as a means of achieving long-term restitution of hematopoiesis across histocompatibility barriers and as a self-renewing vehicle for gene transfer.

Animals↗
PubMed2002

Evolution of viral structure.

Viruses vastly outnumber their host cells and must present a huge selective pressure. It is also becoming evident that only a small percent of the eukaryotic genome codes for molecules involved in cellular structures and functions, and that much of the remainder may have a viral origin. Viruses clearly play a central role in the biosphere, but how is this viral world organized? Classification was originally based on virus morphology and the particular host infected, but now there is an increasing trend to rely on sequence information. The type of genome (e.g., RNA or DNA, single- or double-stranded) provides fundamental classification criteria, while sequence comparisons can provide fine mapping for closely related viruses. However, it is currently very difficult to identify long-range evolutionary relationships. We present here a different approach, based on the idea that each virus has an innate "self." When the structures and functions characteristic of this "self" are identified, then they uncover relationships beyond those accessible from sequence information alone. The new approach is illustrated by sketching some possible viral lineages. We propose that urviruses were present before the division of cellular life into its current domains, and that the viral world has lineages that can be traced back to the root of the universal tree of life.

Biological Evolution↗
PubMed1989

Phenotypic and functional differences in NK and LAK cells in the peripheral blood of sooty mangabeys and rhesus macaques.

Greater than 75% of the sooty mangabey monkeys at the Yerkes Regional Primate Research Center are naturally infected with SIV without any apparent clinical symptomology. On the other hand, experimental infection of rhesus macaques with SIV results in a clinical syndrome similar to human AIDS. These differences with regard to SIV infection prompted us to examine the natural immunosurveillance system of peripheral blood mononuclear cells (PBMC) from SIV-infected and uninfected monkeys of these two species. Phenotypic and functional studies of precursor and effector NK and LAK cells in the PBMC from these two species were carried out using monoclonal reagents, flow microfluorometry (FMF), and the standard in vitro 51Cr release assay against prototype K562 (NK sensitive) and RAJI (NK resistant, LAK susceptible) target cell lines. Data indicate that both NK and LAK cell activities in the PBMC of sooty mangabeys were significantly (P less than 0.01) greater than those in rhesus macaques. The predominant NK effector cells and LAK cell precursors were shown to be Leu 19-CD8+ in the PBMC of sooty mangabeys and Leu19+ CD8- in the PBMC of rhesus macaques as determined by panning depletion techniques and FMF analysis. On the other hand, the predominant LAK effector cells were found to be dual marked Leu 19+ CD8+ in rhesus macaques and Leu 19- CD8+ in sooty mangabeys. These qualitative and quantitative differences were not due to SIV infection of these two species since PBMC from both SIV-seropositive and virus-positive and SIV-sero-negative and virus-negative monkeys gave similar results. Moreover, of importance is the finding that the functional NK and LAK precursor cells are CD8+ and CD8- in sooty mangabeys and rhesus macaques, respectively. These data may have implications for the natural SIV/SMM virus-positive asymptomatic state of sooty mangabeys and may provide useful tools for tracing the ontogeny and lineage derivation of NK and LAK cells.

Animals↗
PubMed2006

Live imaging of lymphatic development in the zebrafish.

The lymphatic system has become the subject of great interest in recent years because of its important role in normal and pathological processes. Progress in understanding the origins and early development of this system, however, has been hampered by difficulties in observing lymphatic cells in vivo and in performing defined genetic and experimental manipulation of the lymphatic system in currently available model organisms. Here, we show that the optically clear developing zebrafish provides a useful model for imaging and studying lymphatic development, with a lymphatic system that shares many of the morphological, molecular and functional characteristics of the lymphatic vessels found in other vertebrates. Using two-photon time-lapse imaging of transgenic zebrafish, we trace the migration and lineage of individual cells incorporating into the lymphatic endothelium. Our results show lymphatic endothelial cells of the thoracic duct arise from primitive veins through a novel and unexpected pathway.

Animals↗
PubMed2004

Serial cultivation of chicken keratinocytes, a composite cell type that accumulates lipids and synthesizes a novel beta-keratin.

The epidermis of birds differs from that of mammals by the presence of intracellular lipid droplets and the absence of sebaceous glands. We describe here the cultivation of chicken epidermal keratinocytes; these cells cannot be grown in medium supplemented with the usual fetal bovine serum even in the presence of supporting 3T3 cells, but they can grow from single cells in the presence of supporting 3T3 cells and 10% chicken serum. As revealed by their cell structure, their protein composition, and their gene expression, chicken keratinocytes possess the general properties of mammalian keratinocytes. They ultimately undergo in culture a process of terminal differentiation in which their nucleus is destroyed and a cornified envelope is formed. Chicken keratinocytes also show important properties that mammalian keratinocytes do not possess: they accumulate neutral lipids, usually in the form of a single perinuclear droplet; they accumulate carotenoids; they synthesize beta-keratins; and their multiplication requires a non-lipid factor, present in chicken serum but not in fetal calf serum. The lipid-synthesizing function of sebocytes in mammals is carried out by the keratinocytes themselves in birds. The availability of cultured chicken keratinocytes should allow studies that were hitherto impossible such as the tracing of the keratinocyte lineage during development of the chicken embryo and the investigation of the complete life cycle of viruses that require specific chicken keratinocyte products (such as Marek's disease virus).

Amino Acid Sequence↗
PubMed1983

The embryonic cell lineage of the nematode Caenorhabditis elegans.

The embryonic cell lineage of Caenorhabditis elegans has been traced from zygote to newly hatched larva, with the result that the entire cell lineage of this organism is now known. During embryogenesis 671 cells are generated; in the hermaphrodite 113 of these (in the male 111) undergo programmed death and the remainder either differentiate terminally or become postembryonic blast cells. The embryonic lineage is highly invariant, as are the fates of the cells to which it gives rise. In spite of the fixed relationship between cell ancestry and cell fate, the correlation between them lacks much obvious pattern. Thus, although most neurons arise from the embryonic ectoderm, some are produced by the mesoderm and a few are sisters to muscles; again, lineal boundaries do not necessarily coincide with functional boundaries. Nevertheless, cell ablation experiments (as well as previous cell isolation experiments) demonstrate substantial cell autonomy in at least some sections of embryogenesis. We conclude that the cell lineage itself, complex as it is, plays an important role in determining cell fate. We discuss the origin of the repeat units (partial segments) in the body wall, the generation of the various orders of symmetry, the analysis of the lineage in terms of sublineages, and evolutionary implications.

Animals↗