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At least 703 records · Page 39Linked to original sources
PubMed1995

Expression pattern of CD45 RA/RO isoformic antigens in T-lineage neoplasms.

The expression of CD45 RA/RO antigen was investigated in neoplasms including cases expressing CD7 antigen as the sole pan-T antigen (n = 8), T-lineage acute lymphoblastic leukemia (ALL)/lymphoblastic lymphoma (LBL) at various stages of differentiation (n = 32), peripheral stage T-lineage leukemia (n = 10) and adult T-cell leukemia (ATL) (n = 14). The p56lck gene expression was also investigated in selected cases. The expression pattern of CD45 RA/RO antigen was defined as of RA, mixed, or RO type. All but one CD7+ CD5- CD2- case were of the RA type. The CD7+ CD5+ CD2- prothymic stage included seven RA and one mixed type cases. One CD7+ CD5- CD2+ case was of the RA type, but the other was of the RO type. The CD7+ CD5+ CD2+ prothymic stage included three RA and four mixed type cases. All seven CD3- CD4+ CD8+ (double-positive) thymic cases were of the RO type. The CD3+ CD4+ CD8+ (triple-positive) stage included two RO and three mixed-type cases. One CD3+ CD4+ CD8- late thymic case was of the mixed type. The peripheral stage cases included five RA, three RO, and two mixed type cases. All ATL cases were of the RO type. The expression of p56lck gene in the prothymic stage was less marked than that in the thymic stage. On the basis of these results, the following sequence of pattern of the CD45 RA/RO antigen expression along with T-lineage differentiation was reconstructed: prothymic stage [RA and mixed type]-->double-positive thymic stage [RO type]-->triple-positive thymic stage [RO and mixed type]-->peripheral stage [RA, mixed, and RO type]. While one RO-type CD7+ CD5- CD2- and one RO-type CD7+ CD5- CD2+ cases were not in accord with this sequence, the pattern of CD45 RA/RO antigen expression in most of T-lineage neoplasms could be determined by the respective stage of differentiation. The poor expression of the p56lck gene by the prothymic blasts compared with the thymic blasts may be related to the expression pattern of the CD45 RA/RO molecules, which exhibits phosphatase activity. The consistent RO-type expression in the ATL cases may reflect the activated status of the neoplastic T cells due to the presence of the HTLV-I gene. Alternatively, the target cells for HTLV-I-induced neoplastic transformation may possible be of the RO type.

Adolescent↗
PubMed1997

Two separable T cell receptor signals reconstitute positive selection of CD4 lineage T cells in vivo.

Positive selection is an obligatory step during intrathymic T cell differentiation. It is associated with rescue of short-lived, self major histocompatibility complex (MHC)-restricted thymocytes from programmed cell death, CD4/CD8 T cell lineage commitment, and induction of lineage-specific differentiation programs. T cell receptor (TCR) signaling during positive selection can be closely mimicked by targeting TCR on immature thymocytes to cortical epithelial cells in situ via hybrid antibodies. We show that selection of CD4 T cell lineage cells in mice deficient for MHC class I and MHC class II expression can be reconstituted in vivo by two separable T cell receptor signaling steps, whereas a single TCR signal leads only to induction of short-lived CD4+CD8lo intermediates. These intermediates remain susceptible to a second TCR signal for 12-48 h providing an estimate for the duration of positive selection in situ. While both TCR signals induce differentiation steps, only the second one confers long-term survival on immature thymocytes. In further support of the two-step model of positive selection we provide evidence that CD4 T cell lineage cells rescued by a single hybrid antibody pulse in MHC class II-deficient mice are pre-selected by MHC class I.

Animals↗
PubMed1997

Alpha beta lineage-committed thymocytes can be rescued by the gamma delta T cell receptor (TCR) in the absence of TCR beta chain.

Commitment of the alpha beta and gamma delta T cell lineages within the thymus has been studied in T cell receptor (TCR)-transgenic and TCR mutant murine strains. TCR gamma delta-transgenic or TCR beta knockout mice, both of which are unable to generate TCR alpha beta-positive T cells, develop phenotypically alpha beta-like thymocytes in significant proportions. We provide evidence that in the absence of functional TCR beta protein, the gamma delta TCR can promote the development of alpha beta-like thymocytes, which, however, do not expand significantly and do not mature into gamma delta T cells. These results show that commitment to the alpha beta lineage can be determined independently of the isotype of the TCR, and suggest that alpha beta versus gamma delta T cell lineage commitment is principally regulated by mechanisms distinct from TCR-mediated selection. To accommodate our data and those reported previously on the effect of TCR gamma and delta gene rearrangements on alpha beta T cell development, we propose a model in which lineage commitment occurs independently of TCR gene rearrangement.

Animals↗
PubMed1993

Development of cell-cell coupling among cells of the oligodendrocyte lineage.

The development of functional gap-junctional communication was studied in cells of the oligodendrocyte lineage. The presence of cell-cell coupling was determined by the passage of current between cells using a double whole-cell patch-clamp system or by injecting the low molecular weight dye Lucifer yellow into individual cells via a patch pepette and observing the diffusion of the dye into adjacent cells. The developmental stage of the cells under study was determined using antibodies to specific surface markers (04, 01, and 010) that characterize cells of sequential maturity along the oligodendrocyte lineage (Kuhlmann-Krieg et al., 1988; Sommer and Schachner, 1981; 1982). Both stages of precursor cells of this lineage, O4+ and O4-, almost never showed dye or electrical coupling, even though they were in close physical contact with other cells. The O1-positive oligodendrocytes with simple morphology were also noncoupled, with only few exceptions. In contrast, more than 40 percent of more mature, O10-positive oligodendrocytes showed cell-cell coupling detectable with both dye and current injection. Thus, the formation of gap junctions between cells of the oligodendrocyte lineage does not occur with, but some time after, the commitment of the cell to becoming an oligodendrocyte.

Animals↗
PubMed1993

Lineage commitment in human hemopoiesis involves asymmetric cell division of multipotent progenitors and does not appear to be influenced by cytokines.

Different models have been proposed to explain lineage commitment in hemopoiesis. Some suggest that lineage commitment occurs in a stochastic manner without the direct influence of extracellular factors; others postulate that cytokines determine whether multipotent cells will become erythroid or granulocyte/macrophage progenitors. In the present study, the patterns of proliferation and differentiation of individually sorted human cord blood-derived primitive hemopoietic cells (highly enriched for multipotent progenitors) were analyzed in a serum-free culture system supplemented with different cytokine combinations. In a first set of experiments, the response of individual cells to different cytokine combinations was compared, whereas in a second set of experiments, single cells were allowed to undergo one division after which the two daughter cells were physically separated and cultured in either the same or different cytokine combinations. Proliferation of progenitor cells was absolutely dependent on cytokines, and the combination of mast cell growth factor plus interleukin 6 was sufficient to induce mitosis. When cytokine combinations favoring erythropoiesis and/or myelopoiesis were added to the cultures, a more vigorous proliferative response of the sorted primitive progenitors was observed. Interestingly, the relative proportions of granulocyte/macrophage, erythroid, and multipotent progenitors remained more or less the same regardless of the cytokine combination used, indicating a permissive rather than an instructive role for cytokines in hemopoietic differentiation. Asymmetric cell divisions, defined as a division that yields two daughter cells with distinct functional properties, were observed in 3-17% of the progenitor cells capable of forming colonies under our experimental conditions. In the rest, symmetric divisions involving multipotent and lineage-committed progenitors were observed. The results of this study demonstrate that the asymmetric cell divisions that occur in the early stages of hemopoiesis at the level of multipotent progenitors cannot be skewed by the addition of specific cytokine combinations. These findings support the hypothesis that lineage commitment in hemopoiesis occurs in a stochastic manner by mechanisms that remain to be elucidated.

Antigens, CD↗
PubMed1992

Immunoglobulin-containing cells in chick embryo urogenital tissues: a new site for early B lineage cells in endothermic vertebrates.

We have employed histological and immunofluorescent staining procedures in order to characterize the distribution of mu + B lineage cells in tissue sections prepared from developing chicken embryo urogenital tissues (UGTs) between 14 and 21 days of incubation. B lineage cells were observed in tissue sections prepared from developing UGTs, especially the mesonephros and its associated tissue, throughout the sample period. The highest densities of mu + B lineage cells were observed in tissue sections prepared from 18 day embryos. The mu + UGT cells were distributed singly and in clusters in subcapsular regions and within the peritubular interstitium of the mesonephros. These observations (1) are consistent with those which suggest nonbursal site(s) for origin of cells in B lineage, (2) may help account for the varying effects of embryonic caudectomy performed between the second and third days of incubation and surgical bursectomy performed close to hatching, (3) may help provide new insights on the effects of sex hormones on B cell development, and (4) suggest fundamental ontogenetic and phylogenetic similarities between developing vertebrate immune systems.

Animals↗
PubMed2003

Evolutionary transformations of the fetal membranes of viviparous reptiles: a case study of two lineages.

The reptilian placenta is a composite structure formed by a functional interaction between extraembryonic membranes and the maternal uterus. Study of placental structure of squamate reptiles over the past century has established that each of the multiple independent origins of placentation, which characterize the reproductive diversity of squamates, has resulted from the evolutionary transformation of these homologous structures. Because each evolutionary transformation is an independent novel relationship between maternal and embryonic tissues, the resulting placentae are not homologous, even though the individual components may be. The evolution of reptilian placentation should reveal much about evolutionary patterns and mechanisms because similar structural-functional systems have been transformed along parallel trajectories on multiple occasions. We compared extraembryonic membrane and placental development and pattern of embryonic nutrition in thamnophiine snakes and Pseudemoia lizards in the context of recent hypotheses of phylogenetic relationships. Two primary types of placentation, chorioallantoic and yolk sac, evolved in each lineage. Smooth, highly vascular regions of chorioallantoic placentation are indistinguishable homoplasies that evolved in parallel, likely to facilitate respiratory exchange. The yolk sac placenta of each lineage is specialized for histotrophic nutrient transfer, yet composition of these structures differs because of variation in the ancestral snakes and lizards. In addition, the omphalopleure that contributes to yolk sac placentation persists to later embryonic stages compared to oviparous outgroups, but the two lineages have evolved different structures that prevent replacement of the omphalopleure by the allantois. Each lineage has also evolved unique structural specializations of the chorioallantoic placenta.

Allantois↗
PubMed1990

Quantitative comparison of myeloid antigens on five lineages of mature peripheral blood cells.

Five-dimensional flow cytometry was used to identify the 5 lineages of peripheral blood leukocytes simultaneously in a single cell preparation. This technique was then used to compare quantitatively the distribution of cell surface antigens on each of these lineages of cells. Neutrophils, eosinophils, basophils, lymphocytes, and monocytes were uniquely identified by correlating their forward and orthogonal light scattering signals with the amount of cell surface-bound IgE. These three cellular characteristics were combined with two additional immunofluorescence labels to create a 5-dimensional space in which each leukocyte population occupied a unique position. The relative quantities of antigens on each cell type were determined for the monoclonal antibodies CD11b, CD13, CD14, CD15, CD16, CD33, CD38, CD45, CD45R, anti-HLA-DR, and anti-Leu-8 labeled with either fluorescein or phycoerythrin. The amount of antigen was described by the mean fluorescence intensity in comparison with the background fluorescence of each cell type. The distribution of the different cell surface antigens on the 5 major leukocyte populations as well as their interdonor variation were then correlated for 10 normal donors. Since none of the antigens studied was lineage specific, it was shown that the different lineages of blood cells could clearly be identified by quantitative comparison of the antigens. This study provides the basis for discrimination between mature cells and immature stages of differentiation of leukocytes and for distinction between normal and leukemic cells.

Antigens, CD↗
PubMed1993

Ulcer-associated cell lineage ('pyloric metaplasia') in Crohn's disease: a lectin histochemical study.

Chronic intestinal ulceration in Crohn's disease is associated with the development of an epidermal growth factor-secreting cell lineage, or 'ulcer-associated cell lineage' (UACL). Expression of oligosaccharides by UACL was studied using a panel of 25 biotinylated lectins with an avidin peroxidase revealing system and compared with that of adult and fetal Brunner's glands, gastric antral mucosa, and 'gastric metaplasia' within the duodenum, in order to clarify further the interrelationships of these lineages. UACL was obtained from ileal resections performed for Crohn's disease. Lectin binding of the glandular component of UACL closely resembled that of antral mucosal glands and also that of fetal and adult Brunner's glands. Lectin binding of the ductal component of immature UACL, in which a surface component had not developed, resembled that of the gland. The surface and ductal components of mature UACL showed a distinct lectin-binding profile, which was very different from that of the gland, but closely resembled that of antral foveolar epithelium and 'gastric metaplasia' within the duodenum. It is concluded that there is differentiation of UACL from the glandular to surface components and that oligosaccharide expression of the lineage reflects that of normal Brunner's gland and gastric antral mucosa.

Brunner Glands↗
PubMed1997

Intrathymically injected hemopoietic stem cells can differentiate into all lineage cells in the thymus: differences between c-kit+ cells and c-kit < low cells.

To investigate whether hemopoietic stem cells (HSCs) can differentiate into all lineage cells even in the thymus, we injected two types of HSCs (c-kit+ and c-kit < low cells) obtained from C57BL/6 Ly5.1 mice directly into the thymus of 7.5 Gy-irradiated C57BL/6 Ly5.2 mice. When c-kit < low cells (low density/lineage-/CD71-/major histocompatibility complex class I high/Sca-1+/Thy-1low/ c-kit < low) were injected, donor-derived (Ly5.1) cells were detected on day 8 after intrathymic (i.t.) injection, and the number reached a maximum on day 24 after injection. Granulocytes and macrophages were also detected on day 8 after injection. However, B220+ B cells were observed on day 13. Eighteen days after i.t. injection, the injected lobes showed red color due to the synchronous development of erythroid cells. Histological studies revealed the development not only of erythroid lineage cells but also of megakaryocytes in the thymus. In contrast, when c-kit+ cells were injected, a significant number of donor-derived cells were detected on day 5 after i.t. injection (three days earlier than in the case of c-kit < low cell injection). The differentiation into erythroid lineage cells was also observed six days earlier than when c-kit < low HSCs were injected. These findings suggest that c-kit < low HSCs are more primitive than c-kit+ HSCs, although both can differentiate into all lineage cells after i.t. injection.

Animals↗
PubMed1983

Surface antigens of murine hemopoietic stem cells. VIII. Antisera define lineage antigens held in common between granulocyte-macrophage cells and between lymphoid cells.

The cell-lineage model of hemopoietic cell differentiation has been further investigated by detailed absorption analysis of the anti-stem cell activity in rabbit antisera against mouse hemopoietic cells. Of seven differentiated hematopoietic cells tested, platelets alone absorbed the anti-stem cell activity in anti-platelet serum. Thymocytes and B-lymphocytes absorbed all of the anti-stem cell activity in antithymocyte serum whereas other nonlymphocytic cells showed only partial absorbing ability. Macrophages and granulocytic cells absorbed most of the anti-stem cell activity in antimacrophage serum and antineutrophil serum whereas other cell types showed little or no absorbing capacity. Antisera against a cloned mast cell precursor line showed partial cell lineage activity whereas anti-sera against eosinophils and B-lymphocytes showed no evidence of cell lineage activity. A detailed model of cell lineage antigens on hemopoietic cells is presented.

Animals↗
PubMed1993

A theoretical and experimental examination of cell lineage relationships among cerebellar Purkinje cells in the mouse.

In this paper, we continue our examination of the role of cell lineage in the development of the cerebellar Purkinje cell population of the mouse. The analysis of Purkinje cell lineage is based on counts of the number of wild-type Purkinje cells in +/Lc<==>wild-type chimeras. +/Lc Purkinje cells undergo a cell autonomous degeneration early in postnatal development leaving variable numbers of wild-type Purkinje cells in chimeric animals. Using theoretical, statistical, and experimental approaches, we have tested various developmental models to account for the numerical development of Purkinje cell numbers in the +/Lc<==>wild-type chimeras. We have analyzed models based on the assumption that cell lineages are irrelevant to Purkinje cell development, as well as our own previous hypothesis that Purkinje cells descend from a small number of progenitor cells selected during the early stages of neurogenesis. The theoretical approach calculates the distributions of Purkinje cell numbers in hypothetical +/Lc<==>wild-type chimeras and inbred mice based on both clonal and nonclonal hypotheses of neuronal development. Variations of the model are compared with published cell counts from +/Lc<==>C3H/HeJ, +/Lc<==>C57BL/6J, +/Lc<==>AKR/J chimeras, and C3H/HeJ inbred mice. The statistical approach assesses the significance of the fits of the observed data with different variations of the model by Monte Carlo simulation techniques. The results of the comparison suggest that our observed data is more likely to be explained by a clonal model of development than by alternate models in which cell lineages play a minor role. Our experimental approach describes a new +/Lc<==>C3H/HeJ chimera in which all of the Purkinje cells (> 7900) are found on one side of the brain. We have analyzed this chimera with respect to clonal and nonclonal models of Purkinje cell development. The extreme asymmetric distribution of Purkinje cells provides added support to the hypothesis that there is a small number of progenitor cells that generate Purkinje cells. Our findings lead to the conclusion that while not all alternate models of mammalian CNS development can be completely excluded, the early progenitor hypothesis is the most probable model of Purkinje cell development.

Animals↗
PubMed1995

Diversification of cardiomyogenic cell lineages in vitro.

The ability of undifferentiated cardiogenic mesoderm to generate diversified myogenic phenotypes was assayed in a minimal culture system. During cardiogenesis in vivo, the anterior and posterior segments of the avian heart have distinct patterns of contractile protein gene expression when they first differentiate. To assess the potential of undifferentiated cardiogenic tissue to diversify into distinct anterior and posterior lineages prior to heart formation, cardiogenic mesoderm and endoderm were removed together from the embryo at Hamburger and Hamilton stages 4-8. Explants from each of these stages differentiated in defined medium as indicated by the expression of muscle-specific genes. However, the ability to express the atrial-specific myosin heavy chain (AMHC) mRNA was confined to posterior cardiac progenitors. Diversification was not dependent on anterior endoderm, suggesting that inductive interactions between the mesoderm and endoderm are not necessary to maintain diversified cardiac lineages after stage 4. The diversified potential of explanted cardiogenic tissue was altered with retinoic acid treatment, resulting in the activation of AMHC1 gene expression in the anterior progenitors. Anterior cardiogenic cells removed from the embryo at stage 8, when the heart begins to differentiate in vivo, are not susceptible to the alteration of diversified phenotype by retinoic acid treatment. Therefore, the potential to form distinct cardiomyogenic cell lineages is present in the anterior lateral plate mesoderm soon after gastrulation and the maturation of these lineages in a positionally dependent manner is maintained in a simple defined culture system in vitro.

Animals↗
PubMed1996

Lineage-specific regulation of the neural differentiation gene MASH1.

Mash1 is a transcription factor required during embryogenesis for the development of multiple neural lineages. It is expressed in restricted domains at specific stages in the developing central and peripheral nervous systems and in the developing olfactory epithelium. We have investigated the regulation of Mash1 expression during embryogenesis using transgenic mice containing Mash1/lacZ reporter constructs. Cis-acting regulatory elements controlling Mash1 expression in the central nervous system are located within an 8-kb sequence upstream of the Mash1 coding region. This 8-kb sequence does not contain elements directing expression to the peripheral nervous system, olfactory epithelium, or retina. Sequences outside this 8 kb but within 36 kb of the Mash1 locus contain elements responsible for expression in the autonomic division of the peripheral nervous system. However, transgene expression in embryos containing the 36-kb sequence was never detected in the olfactory epithelium and retina. Thus, regulatory elements driving expression in these lineages may be at even greater distances from the Mash1 coding region. These data provide evidence for complex regulation of Mash1 expression in which multiple lineage-specific cis-acting regulatory regions span greater than 36 kb of the Mash1 locus. Further characterization of these regions will facilitate the study of factors that regulate the temporal and spatial expression of Mash1 during development. In addition, the regulatory sequences identified here can direct expression of heterologous genes to developing neural lineages that normally express Mash1, thus providing an important tool for examining the function of candidate regulatory genes in mammalian nervous system development.

Animals↗
PubMed1998

Lineage-specific regulation of the Ciona snail gene in the embryonic mesoderm and neuroectoderm.

The snail gene encodes a highly conserved, zinc-finger transcription factor that has been implicated in the specification of mesodermal and neuronal tissues in a variety of organisms. In the ascidian, Ciona intestinalis, snail (Ci-sna) is expressed at the 32-cell stage in derivatives of the B4.1 blastomere, including B6.2, B6.4, and B7.5, which give rise to the primary-lineage tail muscles of the tadpole. At later stages, Ci-sna is expressed in the lineages that will form the secondary tail muscle, the lateral ependymal cells of the spinal cord, and the dorsal cells of the cerebral vesicle. A minimal, 504-bp cis-regulatory sequence from the Ci-sna promoter region, the B4.1 enhancer, is shown to direct the expression of heterologous promoters in primary-lineage muscles. Furthermore, evidence is presented that cis-regulatory elements necessary for expression in both the secondary muscle and neuronal lineages are separate from the B4.1 enhancer. We discuss the possibility that the classical muscle determinant present in ascidian eggs may correspond to bHLH activators, which bind to specific E-box sequences contained in the B4.1 enhancer.

Animals↗
PubMed1999

Transcription of the myogenic regulatory gene Mef2 in cardiac, somatic, and visceral muscle cell lineages is regulated by a Tinman-dependent core enhancer.

The MADS-box transcription factor MEF2 is expressed specifically in developing cardiac, somatic, and visceral muscle cell lineages during Drosophila embryogenesis and is required for myoblast differentiation and muscle morphogenesis. To define the mechanisms that regulate Mef2 transcription, we have analyzed the Mef2 upstream region for sequences sufficient to recapitulate the expression pattern of the gene in Drosophila embryos. Here we describe a complex enhancer located 5.8 kb upstream of the Drosophila Mef2 gene that controls transcription in cardial cells of the dorsal vessel, a subset of somatic muscle founder cells, and the visceral muscle cells. The core of this enhancer contains two evolutionarily conserved binding sites for the homeodomain protein Tinman (Tin), expressed in developing cardiac, somatic, and visceral muscle lineages. Both Tin binding sites are required for enhancer activity in all three muscle cell lineages. Whereas the 285-bp enhancer core alone is sufficient for expression in cardiac cells, expression in somatic founder cells and visceral muscle is dependent on the core enhancer plus unique flanking sequences that include an evolutionarily conserved E box. These results reveal an essential role for Tin in activation of Mef2 transcription in multiple myogenic lineages and demonstrate that transcriptional activity of Tin is dependent on combinatorial interactions with other factors unique to different muscle cell types.

Animals↗
PubMed2001

Birth of a gene: locus of neuronal BC200 snmRNA in three prosimians and human BC200 pseudogenes as archives of change in the Anthropoidea lineage.

The gene encoding brain-specific dendritic BC200 small non-messenger RNA is limited to the primate order and arose from a monomeric Alu element. It is present and neuronally expressed in all Anthropoidea examined. By comparing the human sequence of about 13.2 kb with each of the prosimian (lemur 14.6 kb, galago 12 kb, and tarsier 13.8 kb) orthologous loci, we could establish that the BC200 RNA gene is absent from the prosimian lineages. In Strepsirhini (lemurs and lorises), a dimeric AluJ-like element integrated very close to the BC200 insertion point, while the corresponding tarsier region is devoid of any repetitive element. Consequently, insertion of the Alu monomer that gave rise to the BC200 RNA gene must have occurred after the anthropoid lineage diverged from the prosimian lineage(s). Shared insertions of other repetitive elements favor proximity of simians and tarsiers in support of their grouping into Haplorhini and the omomyid hypothesis. On the other hand, the nucleotide sequences in the segment that is available for comparison in all four species reveal less exchanges between Strepsirhini (lemur and galago) and human than between tarsier and human. Our data imply that the early activity of dimeric Alu sequences must have been concurrent with the activity of monomeric Alu elements that persisted longer than is usually thought. As BC200 RNA gave rise to more than 200 pseudogenes, we used their consensus sequence variations as a molecular archive recording the BC200 RNA sequence changes in the anthropoid lineage leading to Homo sapiens and timed these alterations over the past 35-55 million years.

Alu Elements↗
PubMed1999

A molecular phylogeny of the pheasants and partridges suggests that these lineages are not monophyletic.

Cytochrome b and D-loop nucleotide sequences were used to study patterns of molecular evolution and phylogenetic relationships between the pheasants and the partridges, which are thought to form two closely related monophyletic galliform lineages. Our analyses used 34 complete cytochrome b and 22 partial D-loop sequences from the hypervariable domain I of the D-loop, representing 20 pheasant species (15 genera) and 12 partridge species (5 genera). We performed parsimony, maximum likelihood, and distance analyses to resolve these phylogenetic relationships. In this data set, transversion analyses gave results similar to those of global analyses. All of our molecular phylogenetic analyses indicated that the pheasants and partridges arose through a rapid radiation, making it difficult to establish higher level relationships. However, we were able to establish six major lineages containing pheasant and partridge taxa, including one lineage containing both pheasants and partridges (Gallus, Bambusicola and Francolinus). This result, supported by maximum likelihood tests, indicated that the pheasants and partridges do not form independent monophyletic lineages.

Animals↗