scholarly journals Differential expression of the Xenopus laevis tadpole and adult beta-globin genes when injected into fertilized Xenopus laevis eggs.

1984 ◽  
Vol 4 (3) ◽  
pp. 567-570 ◽  
Author(s):  
M M Bendig ◽  
J G Williams
Keyword(s):  
Xenopus Laevis ◽  
Differential Expression ◽  
Maximum Level ◽  
Globin Genes ◽  
Beta Globin ◽  
Stages Of Development ◽  
Chromosomal Genes ◽  
Xenopus Laevis Tadpole

Xenopus laevis tadpole and adult beta-globin genes were injected into fertilized X. laevis eggs. Both injected genes replicated and were retained in the developing embryos with equal efficiency. Transcripts of the injected adult gene were detectable at gastrulation and reached a maximum level shortly thereafter. In contrast, transcripts of the injected tadpole gene were not detected until much later stages of development. The level of expression of both the injected genes was low compared with the level of expression of the chromosomal genes during erythropoiesis.

Differential expression of the Xenopus laevis tadpole and adult beta-globin genes when injected into fertilized Xenopus laevis eggs

1984 ◽  
Vol 4 (3) ◽  
pp. 567-570
Author(s):  
M M Bendig ◽  
J G Williams
Keyword(s):  
Xenopus Laevis ◽  
Differential Expression ◽  
Maximum Level ◽  
Globin Genes ◽  
Beta Globin ◽  
Stages Of Development ◽  
Chromosomal Genes ◽  
Xenopus Laevis Tadpole

Xenopus laevis tadpole and adult beta-globin genes were injected into fertilized X. laevis eggs. Both injected genes replicated and were retained in the developing embryos with equal efficiency. Transcripts of the injected adult gene were detectable at gastrulation and reached a maximum level shortly thereafter. In contrast, transcripts of the injected tadpole gene were not detected until much later stages of development. The level of expression of both the injected genes was low compared with the level of expression of the chromosomal genes during erythropoiesis.

scholarly journals CD14+ monocytes repress gamma globin expression at early stages of erythropoiesis

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Steven Heshusius ◽  
Esther Heideveld ◽  
Marieke von Lindern ◽  
Emile van den Akker
Keyword(s):  
Mononuclear Cells ◽  
Therapeutic Option ◽  
Globin Genes ◽  
Beta Globin ◽  
Hematopoietic Progenitors ◽  
Peripheral Blood Mononuclear ◽  
Temporal Regulation ◽  
Gamma Globin ◽  
Cd34 Cells ◽  
Adult Hemoglobin

AbstractIn β-hemoglobinopathies, reactivation of gamma- at the expense of beta-globin is a prominent therapeutic option. Expression of the globin genes is not strictly intrinsically regulated during erythropoiesis, supported by the observation that fetal erythroid cells switch to adult hemoglobin expression when injected in mice. We show cultured erythroblasts are a mix of HbA restrictive and HbA/HbF expressing cells and that the proportion of cells in the latter population depends on the starting material. Cultures started from CD34+ cells contain more HbA/HbF expressing cells compared to erythroblasts cultured from total peripheral blood mononuclear cells (PBMC). Depletion of CD14+ cells from PBMC resulted in higher HbF/HbA percentages. Conversely, CD34+ co-culture with CD14+ cells reduced the HbF/HbA population through cell–cell proximity, indicating that CD14+ actively repressed HbF expression in adult erythroid cultures. RNA-sequencing showed that HbA and HbA/HbF populations contain a limited number of differentially expressed genes, aside from HBG1/2. Co-culture of CD14+ cells with sorted uncommitted hematopoietic progenitors and CD34-CD36+ erythroblasts showed that hematopoietic progenitors prior to the hemoglobinized erythroid stages are more readily influenced by CD14+ cells to downregulate expression of HBG1/2, suggesting temporal regulation of these genes. This possibly provides a novel therapeutic avenue to develop β-hemoglobinopathies treatments.

Differential expression of the TFF-peptides xP1 and xP4 in the gastrointestinal tract of Xenopus laevis

1997 ◽  
Vol 291 (1) ◽  
pp. 13-18 ◽  
Author(s):  
Wolfgang Jagla ◽  
Antje Wiede ◽  
Sabine K�lle ◽  
W. Hoffmann
Keyword(s):  
Gastrointestinal Tract ◽  
Xenopus Laevis ◽  
Differential Expression ◽  
Tff Peptides

scholarly journals The thyroid hormone receptor gene (c-erbA alpha) is expressed in advance of thyroid gland maturation during the early embryonic development of Xenopus laevis.

1991 ◽  
Vol 11 (10) ◽  
pp. 5079-5089 ◽  
Author(s):  
D E Banker ◽  
J Bigler ◽  
R N Eisenman
Keyword(s):  
Gene Expression ◽  
Thyroid Hormone ◽  
Thyroid Gland ◽  
Xenopus Laevis ◽  
Hormone Receptor ◽  
Hormone Receptors ◽  
Thyroid Hormone Receptor ◽  
Thyroid Hormone Receptors ◽  
Stages Of Development ◽  
Xenopus Development

The c-erbA proto-oncogene encodes the thyroid hormone receptor, a ligand-dependent transcription factor which plays an important role in vertebrate growth and development. To define the role of the thyroid hormone receptor in developmental processes, we have begun studying c-erbA gene expression during the ontogeny of Xenopus laevis, an organism in which thyroid hormone has well-documented effects on morphogenesis. Using polymerase chain reactions (PCR) as a sensitive assay of specific gene expression, we found that polyadenylated erbA alpha RNA is present in Xenopus cells at early developmental stages, including the fertilized egg, blastula, gastrula, and neurula. By performing erbA alpha-specific PCR on reverse-transcribed RNAs from high-density sucrose gradient fractions prepared from early-stage embryos, we have demonstrated that these erbA transcripts are recruited to polysomes. Therefore, erbA is expressed in Xenopus development prior to the appearance of the thyroid gland anlage in tailbud-stage embryos. This implies that erbA alpha/thyroid hormone receptors may play ligand-independent roles during the early development of X. laevis. Quantitative PCR revealed a greater than 25-fold range in the steady-state levels of polyadenylated erbA alpha RNA across early stages of development, as expressed relative to equimolar amounts of total embryonic RNA. Substantial increases in the levels of erbA alpha RNA were noted at stages well after the onset of zygotic transcription at the mid-blastula transition, with accumulation of erbA alpha transcripts reaching a relative maximum in advance of metamorphosis. We also show that erbA alpha RNAs are expressed unequally across Xenopus neural tube embryos. This differential expression continues through later stages of development, including metamorphosis. This finding suggests that erbA alpha/thyroid hormone receptors may play roles in tissue-specific processes across all of Xenopus development.

scholarly journals The nucleotide sequence of the mRNA encoding a tadpole beta-globin polypeptide of Xenopus laevis.

1983 ◽  
Vol 258 (13) ◽  
pp. 7924-7927
Author(s):  
D Banville ◽  
R M Kay ◽  
R Harris ◽  
J G Williams
Keyword(s):  
Nucleotide Sequence ◽  
Xenopus Laevis ◽  
Beta Globin

Activation and repression of a beta-globin gene in cell hybrids is accompanied by a shift in its temporal replication

1989 ◽  
Vol 9 (8) ◽  
pp. 3524-3532
Author(s):  
V Dhar ◽  
A I Skoultchi ◽  
C L Schildkraut
Keyword(s):  
Cell Line ◽  
Hybrid Cell ◽  
Globin Gene ◽  
Fibroblast Cell ◽  
Globin Genes ◽  
Fibroblast Cell Line ◽  
Beta Globin ◽  
Hybrid Cells ◽  
Beta Globin Gene ◽  
Cell Hybrids

To investigate whether a switch in the transcriptional activity of a gene is associated with a change in the timing of replication during the S phase, we examined the replication timing of the beta-globin genes in two different types of somatic cell hybrids. In mouse hepatoma (Hepa 1a) x mouse erythroleukemia (MEL) hybrid cells, the beta-globin gene from the MEL parent is transcriptionally inactivated and is later replicating than in the parental MEL cell line. In human fibroblast (GM3552) x MEL hybrid cells, the human beta-globin gene is transcriptionally activated, and all of the sequences within the human beta-globin domain (200 kilobases) we have examined appear to be earlier replicating than those in the parental fibroblast cell line. The chromatin configuration of the activated human beta-globin domain in the hybrids is relatively more sensitive to nucleases than that in the fibroblasts. Furthermore, major nuclease-hypersensitive sites that were absent in the chromatin flanking the distal 5' region of the human beta-globin gene cluster in the parental fibroblast cell line are present in the transcriptionally activated domain in the hybrid cell line. These results suggest that timing of replication of globin genes has been altered in these hybrid cells and thus is not fixed during the process of differentiation.

The coordinate replication of the human beta-globin gene domain reflects its transcriptional activity and nuclease hypersensitivity

1988 ◽  
Vol 8 (11) ◽  
pp. 4958-4965
Author(s):  
V Dhar ◽  
D Mager ◽  
A Iqbal ◽  
C L Schildkraut
Keyword(s):  
Cell Lines ◽  
Dna Sequences ◽  
Globin Gene ◽  
K562 Cells ◽  
Globin Genes ◽  
Beta Globin ◽  
Beta Globin Gene ◽  
Hypersensitive Sites ◽  
Flanking Sequences ◽  
Globin Gene Domain

The temporal order of replication of DNA sequences in the chromosomal domain containing the human beta-globin gene cluster and its flanking sequences (140 kilobases) was measured and compared in two different human cell lines. In human erythroleukemia (K562) cells, in which embryonic and fetal globin genes are transcribed, all of the sequences we examined from the beta-globin domain replicated early during S phase, while in HeLa cells, in which globin genes are transcriptionally silent, these sequences replicated late during S. Potential sites of initiation of DNA replication within this domain were identified. The beta-globin gene domain was also found to differ with respect to the nuclease sensitivity of the chromatin in these two cell lines. In K562 cells, hypersensitive sites for endogenous nucleases and DNase I were present in the chromatin near the earliest-replicating segments in the beta-globin domain.

Fidelity of transcription of Xenopus laevis globin genes injected into Xenopus laevis oocytes and unfertilized eggs

1984 ◽  
Vol 4 (10) ◽  
pp. 2109-2119
Author(s):  
M M Bendig ◽  
J G Williams
Keyword(s):  
Xenopus Laevis ◽  
Chromatin Structure ◽  
Plasmid Dna ◽  
Xenopus Laevis Oocytes ◽  
Globin Genes ◽  
Low Level ◽  
Circular Plasmid

The Xenopus laevis alpha 1- and beta 1-globin genes were injected into oocytes and unfertilized eggs of X. laevis. In oocytes, the injected globin genes were actively transcribed, but the majority of the transcripts were incorrectly initiated. In unfertilized eggs, the injected genes were transcribed at a low level but only from the correct start sites. In oocytes, the injected circular plasmid DNA containing the cloned globin genes persisted but did not replicate. In contrast, DNA injected into unfertilized eggs replicated up to 15-fold within a 22-h period. We suggest that the ability of the egg to selectively transcribe the injected X. laevis globin genes from the correct promoter sites may be related to differences in chromatin structure between the oocyte and the unfertilized egg.

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