Metabolic gradients and morphological polarization in embryonic development of hydroid polypes

Development ◽  
1969 ◽  
Vol 22 (3) ◽  
pp. 431-447
Author(s):  
L. V. Belousov ◽  
T. V. Ostroumova
Keyword(s):  
Cell Differentiation ◽  
Embryonic Development ◽  
General Principle ◽  
Regional Differences ◽  
Metabolic Processes ◽  
Metabolic Conditions ◽  
Physiological Gradients

One of the main problems of modern embryology is the problem of relations between morphogenetic and metabolic processes. For several decades this problem was studied under the influence of the theory of physiological gradients and of some of its modifications (Child, 1941; Dalcq & Pasteels, 1938). The general principle of these conceptions was that the processes of cell differentiation were strictly determined by previous regional metabolic conditions (metabolic, or physiological gradients). The gradients were supposed in their turn to be determined by the heterogeneity of the embryo's environment. Therefore, a simple and non-reversible chain of relationships was postulated: heterogeneity of environment → graded metabolic differences → regional differences at the cellular or supracellular levels. No possibility of any kind of inverse relations—that is, influence of cellular and supracellular events upon the metabolic processes—was taken into account in these conceptions. More recently however a number of facts were obtained which demonstrate the possibility of reverse relations.

scholarly journals Wnt signaling in kidney: the initiator or terminator?

2020 ◽  
Vol 98 (11) ◽  
pp. 1511-1523 ◽  
Author(s):  
Ping Meng ◽  
Mingsheng Zhu ◽  
Xian Ling ◽  
Lili Zhou
Keyword(s):  
Cell Differentiation ◽  
Embryonic Development ◽  
Wnt Signaling ◽  
Tissue Repair ◽  
Progenitor Cell ◽  
Kidney Development ◽  
Kidney Diseases ◽  
Electrolyte Balance ◽  
Tissue Repair And Regeneration

Abstract The kidney is a key organ in the human body that excretes toxins and sustains the water–electrolyte balance. During embryonic development and disease progression, the kidney undergoes enormous changes in macrostructure, accompanied by a variety of microstructural histological changes, such as glomerular formation and sclerosis, tubule elongation and atrophy, interstitial establishment, and fibrosis progression. All of these rely on the frequent occurrence of cell death and growth. Notably, to overcome disease, some cells regenerate through self-repair or progenitor cell differentiation. However, the signaling mechanisms underlying kidney development and regeneration have not been elucidated. Recently, Wnt signaling has been noted to play an important role. Although it is a well-known developmental signal, the role of Wnt signaling in kidney development and regeneration is not well recognized. In this review, we review the role of Wnt signaling in kidney embryonic development, tissue repair, cell division, and progenitor cell differentiation after injury. Moreover, we briefly highlight advances in our understanding of the pathogenic mechanisms of Wnt signaling in mediating cellular senescence in kidney parenchymal and stem cells, an irreversible arrest of cell proliferation blocking tissue repair and regeneration. We also highlight the therapeutic targets of Wnt signaling in kidney diseases and provide important clues for clinical strategies.

scholarly journals The CLAVATA and SHOOT MERISTEMLESS loci competitively regulate meristem activity in Arabidopsis

Development ◽  
1996 ◽  
Vol 122 (5) ◽  
pp. 1567-1575 ◽  
Author(s):  
S.E. Clark ◽  
S.E. Jacobsen ◽  
J.Z. Levin ◽  
E.M. Meyerowitz
Keyword(s):  
Cell Division ◽  
Cell Differentiation ◽  
Embryonic Development ◽  
Genetic Interactions ◽  
Floral Meristem ◽  
Shoot Meristem ◽  
Meristem Development ◽  
Undifferentiated Cells ◽  
Floral Meristems ◽  
Shoot Meristemless

The CLAVATA (CLV1 and CLV3) and SHOOT MERISTEMLESS (STM) genes specifically regulate shoot meristem development in Arabidopsis. CLV and STH appear to have opposite functions: c1v1 and Clv3 mutants accumulate excess undifferentiated cells in the shoot and floral meristem, while stm mutants fail to form the undifferentiated cells of the shoot meristem during embryonic development. We have identified a weak allele of stm (stm-2) that reveals STM is not only required for the establish- ment of the shoot meristem, but is also required for the continued maintenance of undifferentiated cells in the shoot meristem and for proper proliferation of cells in the floral meristem. We have found evidence of genetic interactions between the CLV and STM loci. clv1 and c1v3 mutations partially suppressed the stm-1 and stm-2 phenotypes, and were capable of suppression in a dominant fashion. clv stm double mutants and plants homozygous for stm but heterozygous for clv, while still lacking an embryonic shoot meristem, exhibited greatly enhanced postembryonic shoot and floral meristem development. Although stm phenotypes are recessive, stm mutations dominantly suppressed clv homozygous and heterozygous phenotypes. These results indicate that the stm phenotype is sensitive to the levels of CLV activity, while the clv phenotype is sensitive to the level of STM activity. We propose that these genes play related but opposing roles in the regulation of cell division and/or cell differentiation in shoot and floral meristems.

scholarly journals Administration of Adrenocorticotropic Hormone during Chicken Embryonic Development Prematurely Induces Pituitary Growth Hormone Cells

Endocrinology ◽  
2007 ◽  
Vol 148 (8) ◽  
pp. 3914-3921 ◽  
Author(s):  
S. A. Jenkins ◽  
M. Muchow ◽  
M. P. Richards ◽  
J. P. McMurtry ◽  
T. E. Porter
Keyword(s):  
Cell Differentiation ◽  
Adrenal Gland ◽  
Embryonic Development ◽  
Plasma Levels ◽  
Thyroid Stimulating Hormone ◽  
Pituitary Cells ◽  
Hepatic Expression ◽  
Gh Cells ◽  
Igf I

Treatment of fetal rats and embryonic chickens with exogenous glucocorticoids induces premature GH cell differentiation. However, it is unknown whether the developing adrenal gland is capable of mounting this response autonomously. The present study determined whether stimulation of the adrenal gland in developing chicken embryos through administration of ACTH could induce a premature increase in GH cells. We found that plasma corticosterone and ACTH levels increased between embryonic day (e) 11 and e17, consistent with GH cell (somatotroph) ontogeny. Injection of ACTH into eggs on e9, e10, or e11 increased somatotrophs on e14. In contrast, thyroid-stimulating hormone, CRH, α-MSH, GHRH, and TRH were ineffective. Culture of e11 pituitary cells with ACTH failed to induce somatotrophs, suggesting an indirect action of ACTH on GH cells in vivo. Intravenous administration of ACTH dramatically increased plasma levels of corticosterone within 1 h and increased the percentage of pituitary somatotrophs within 24 h. Although ACTH administration increased the relative abundance of pituitary GH cells, there was no effect on plasma levels of GH, IGF-I, or IGF-II, or in hepatic expression of IGF-I or IGF-II mRNA. We conclude that ACTH administration can increase the population of GH cells in the embryonic pituitary. However, this treatment alone does not lead to downstream activation of hepatic IGF production. These findings indicate that the embryonic adrenal gland, and ultimately anterior pituitary corticotrophs, may function to regulate pituitary GH cell differentiation during embryonic development.

scholarly journals MLL3/MLL4 methyltransferase activities regulate embryonic stem cell differentiation independent of enhancer H3K4me1

2020 ◽  
Author(s):  
Guojia Xie ◽  
Ji-Eun Lee ◽  
Kaitlin McKernan ◽  
Young-Kwon Park ◽  
Younghoon Jang ◽  
...  
Keyword(s):  
Cell Differentiation ◽  
Embryonic Development ◽  
Embryonic Stem ◽  
Stem Cell Differentiation ◽  
Enzymatic Activities ◽  
Early Embryonic Development ◽  
Specific Gene ◽  
Cell Type ◽  
Mouse Development ◽  
Cell Type Specific

Enhancers drive cell-type-specific gene transcription and are marked by H3K4me1. MLL4 (KMT2D), a major H3K4me1 methyltransferase with partial functional redundancy with MLL3 (KMT2C), is critical for enhancer activation and cell-type-specific gene induction during cell differentiation and development. However, the roles of MLL3/4-mediated enhancer H3K4me1 and MLL3/4 enzymatic activities in general in these processes remain unclear. Here, we report that MLL3/4 enzymatic activities are partially redundant during mouse development. Simultaneous elimination of both leads to embryonic lethality around E8.5. Using embryoid body (EB) differentiation as an in vitro model for early embryonic development, we show that Mll3 knockout MLL4 enzyme-dead embryonic stem cells (ESCs) are capable of differentiating towards the three germ layers but display severe cavitation defects, likely due to impaired induction of visceral endoderm. Importantly, MLL3/4-catalyzed H3K4me1 is dispensable for enhancer activation during early EB differentiation and lineage-specific neural differentiation. Together, these results suggest a critical, but enhancer H3K4me1-independent, role of MLL3/4 enzymatic activities in early embryonic development and ESC differentiation.

scholarly journals UTX regulates mesoderm differentiation of embryonic stem cells independent of H3K27 demethylase activity

2012 ◽  
Vol 109 (38) ◽  
pp. 15324-15329 ◽  
Author(s):  
Chaochen Wang ◽  
Ji-Eun Lee ◽  
Young-Wook Cho ◽  
Ying Xiao ◽  
Qihuang Jin ◽  
...  
Keyword(s):  
Cell Differentiation ◽  
Embryonic Development ◽  
Es Cells ◽  
Embryonic Stem ◽  
Es Cell ◽  
Mesoderm Development ◽  
H3k27me3 Level ◽  
Histone H3k27 ◽  
Demethylase Activity

To investigate the role of histone H3K27 demethylase UTX in embryonic stem (ES) cell differentiation, we have generated UTX knockout (KO) and enzyme-dead knock-in male ES cells. Deletion of the X-chromosome-encoded UTX gene in male ES cells markedly decreases expression of the paralogous UTY gene encoded by Y chromosome, but has no effect on global H3K27me3 level, Hox gene expression, or ES cell self-renewal. However, UTX KO cells show severe defects in mesoderm differentiation and induction of Brachyury, a transcription factor essential for mesoderm development. Surprisingly, UTX regulates mesoderm differentiation and Brachyury expression independent of its enzymatic activity. UTY, which lacks detectable demethylase activity, compensates for the loss of UTX in regulating Brachyury expression. UTX and UTY bind directly to Brachyury promoter and are required for Wnt/β-catenin signaling-induced Brachyury expression in ES cells. Interestingly, male UTX KO embryos express normal levels of UTY and survive until birth. In contrast, female UTX KO mice, which lack the UTY gene, show embryonic lethality before embryonic day 11.5. Female UTX KO embryos show severe defects in both Brachyury expression and embryonic development of mesoderm-derived posterior notochord, cardiac, and hematopoietic tissues. These results indicate that UTX controls mesoderm differentiation and Brachyury expression independent of H3K27 demethylase activity, and suggest that UTX and UTY are functionally redundant in ES cell differentiation and early embryonic development.

Sign in / Sign up

Export Citation Format

Share Document