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The effect of hyperammonemia on myostatin and myogenic regulatory factor gene expression in broiler embryos. Animal 2015; 9:992-9. [PMID: 25689990 DOI: 10.1017/s1751731115000117] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Myogenesis is facilitated by four myogenic regulatory factors and is significantly inhibited by myostatin. The objective of the current study was to examine embryonic gene regulation of myostatin/myogenic regulatory factors, and subsequent manipulations of protein synthesis, in broiler embryos under induced hyperammonemia. Broiler eggs were injected with ammonium acetate solution four times over 48 h beginning on either embryonic day (ED) 15 or 17. Serum ammonia concentration was significantly higher (P<0.05) in ammonium acetate injected embryos for both ED17 and ED19 collected samples when compared with sham-injected controls. Expression of mRNA, extracted from pectoralis major of experimental and control embryos, was measured using real-time quantitative PCR for myostatin, myogenic regulatory factors myogenic factor 5, myogenic determination factor 1, myogenin, myogenic regulatory factor 4 and paired box 7. A significantly lower (P<0.01) myostatin expression was accompanied by a higher serum ammonia concentration in both ED17 and ED19 collected samples. Myogenic factor 5 expression was higher (P<0.05) in ED17 collected samples administered ammonium acetate. In both ED17 and ED19 collected samples, myogenic regulatory factor 4 was lower (P⩽0.05) in ammonium acetate injected embryos. No significant difference was seen in myogenic determination factor 1, myogenin or paired box 7 expression between treatment groups for either age of sample collection. In addition, there was no significant difference in BrdU staining of histological samples taken from treated and control embryos. Myostatin protein levels were evaluated by Western blot analysis, and also showed lower myostatin expression (P<0.05). Overall, it appears possible to inhibit myostatin expression through hyperammonemia, which is expected to have a positive effect on embryonic myogenesis and postnatal muscle growth.
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Vastag L, Jorgensen P, Peshkin L, Wei R, Rabinowitz JD, Kirschner MW. Remodeling of the metabolome during early frog development. PLoS One 2011; 6:e16881. [PMID: 21347444 PMCID: PMC3035664 DOI: 10.1371/journal.pone.0016881] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2010] [Accepted: 01/04/2011] [Indexed: 12/27/2022] Open
Abstract
A rapid series of synchronous cell divisions initiates embryogenesis in many animal species, including the frog Xenopus laevis. After many of these cleavage cycles, the nuclear to cytoplasmic ratio increases sufficiently to somehow cause cell cycles to elongate and become asynchronous at the mid-blastula transition (MBT). We have discovered that an unanticipated remodeling of core metabolic pathways occurs during the cleavage cycles and the MBT in X. laevis, as evidenced by widespread changes in metabolite abundance. While many of the changes in metabolite abundance were consistently observed, it was also evident that different female frogs laid eggs with different levels of at least some metabolites. Metabolite tracing with heavy isotopes demonstrated that alanine is consumed to generate energy for the early embryo. dATP pools were found to decline during the MBT and we have confirmed that maternal pools of dNTPs are functionally exhausted at the onset of the MBT. Our results support an alternative hypothesis that the cell cycle lengthening at the MBT is triggered not by a limiting maternal protein, as is usually proposed, but by a decline in dNTP pools brought about by the exponentially increasing demands of DNA synthesis.
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Affiliation(s)
- Livia Vastag
- Carl Icahn Laboratory, Department of Chemistry and Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey, United States of America
| | - Paul Jorgensen
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Leonid Peshkin
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Ru Wei
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America
| | - Joshua D. Rabinowitz
- Carl Icahn Laboratory, Department of Chemistry and Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey, United States of America
| | - Marc W. Kirschner
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, United States of America
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Shiokawa K, Aso M, Kondo T, Takai JI, Yoshida J, Mishina T, Fuchimukai K, Ogasawara T, Kariya T, Tashiro K, Igarashi K. Effects of S-adenosylmethionine decarboxylase, polyamines, amino acids, and weak bases (amines and ammonia) on development and ribosomal RNA synthesis in Xenopus embryos. Amino Acids 2009; 38:439-49. [PMID: 20013010 DOI: 10.1007/s00726-009-0403-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2009] [Accepted: 09/08/2009] [Indexed: 11/24/2022]
Abstract
We have been studying control mechanisms of gene expression in early embryogenesis in a South African clawed toad Xenopus laevis, especially during the period of midblastula transition (MBT), or the transition from the phase of active cell division (cleavage stage) to the phase of extensive morphogenesis (post-blastular stages). We first found that ribosomal RNA synthesis is initiated shortly after MBT in Xenopus embryos and those weak bases, such as amines and ammonium ion, selectively inhibit the initiation and subsequent activation of rRNA synthesis. We then found that rapidly labeled heterogeneous mRNA-like RNA is synthesized in embryos at pre-MBT stage. We then performed cloning and expression studies of several genes, such as those for activin receptors, follistatin and aldolases, and then reached the studies of S-adenosylmethionine decarboxylase (SAMDC), a key enzyme in polyamine metabolism. Here, we cloned a Xenopus SAMDC cDNA and performed experiments to overexpress the in vitro-synthesized SAMDC mRNA in Xenopus early embryos, and found that the maternally preset program of apoptosis occurs in cleavage stage embryos, which is executed when embryos reach the stage of MBT. In the present article, we first summarize results on SAMDC and the maternal program of apoptosis, and then describe our studies on small-molecular-weight substances like polyamines, amino acids, and amines in Xenopus embryos. Finally, we summarize our studies on weak bases, especially on ammonium ion, as the specific inhibitor of ribosomal RNA synthesis in Xenopus embryonic cells.
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Affiliation(s)
- Koichiro Shiokawa
- Department of Judo Therapy, Faculty of Medical Technology, Teikyo University, 1-1 Toyosatodai, Utsunomiya, Tochigi, 320-8551, Japan.
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Abstract
Recent experiments from our laboratory have documented the importance of ammonia as a modulator of renal cell growth in vitro. Ammonia induces renal hypertrophy by increasing the rate of protein synthesis and decreasing the rate of protein degradation. These results have led to the hypothesis that an increase in renal ammoniagenesis contributes to renal growth in several seemingly unrelated clinical disorders. In chronic hypokalemia and metabolic acidosis, mitochondrial ammoniagenesis is stimulated directly. During protein loading, uninephrectomy, and diabetes mellitus, renal ammoniagenesis may be stimulated by an increase in single-nephron glomerular filtration rate (SNGFR).
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Affiliation(s)
- I Kurtz
- Department of Medicine, UCLA School of Medicine 90024-1689
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Shiokawa K. Gene Expression from Endogenou and Exogenously-introduced DNAs in Early Embryogenesis of Xenopus laevis. (Xenopus embryogenesis/nuclear RNA synthesis/midblastula transition/CAT gene injection/actin-CAT fusion gene). Dev Growth Differ 1991. [DOI: 10.1111/j.1440-169x.1991.00001.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Affiliation(s)
- L D Smith
- Department of Developmental and Cell Biology, University of California, Irvine 92717
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Golchini K, Norman J, Bohman R, Kurtz I. Induction of hypertrophy in cultured proximal tubule cells by extracellular NH4Cl. J Clin Invest 1989; 84:1767-79. [PMID: 2480366 PMCID: PMC304054 DOI: 10.1172/jci114361] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Ammonia production increases in several models of renal hypertrophy in vivo. The present study was designed to determine whether ammonia can directly modulate the growth of renal cells in the absence of a change in extracellular acidity. In serum-free media NH4Cl (0-20 mM) caused JTC cells and a primary culture of rabbit proximal tubule cells to hypertrophy (increase in cell protein content) in a dose-dependent fashion without a change in DNA synthesis. Studies in JTC cells revealed that the cell protein content increased as a result of both an increase in protein synthesis and a decrease in protein degradation. Total cell RNA content and ribosome number increased after NH4Cl exposure and the cell content of the lysosomal enzymes cathepsin B and L decreased. Inhibition of the Na+/H+ antiporter with amiloride did not prevent the hypertrophic response induced by NH4Cl. The results indicate that ammonia is an important modulator of renal cell growth and that hypertrophy can occur in the absence of functioning Na+/H+ antiport activity.
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Affiliation(s)
- K Golchini
- Department of Medicine, University of California Los Angeles School of Medicine 90024
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Shiokawa K, Misumi Y, Tashiro K, Nakakura N, Yamana K, Oh-uchida M. Changes in the patterns of RNA synthesis in early embryogenesis of Xenopus laevis. CELL DIFFERENTIATION AND DEVELOPMENT : THE OFFICIAL JOURNAL OF THE INTERNATIONAL SOCIETY OF DEVELOPMENTAL BIOLOGISTS 1989; 28:17-25. [PMID: 2478271 DOI: 10.1016/0922-3371(89)90019-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
We analyzed the accumulation of newly-synthesized heterogeneous mRNA-like RNA, 4 S RNA, 5 S RNA, snRNAs and rRNA before and after the midblastula transition (MBT) in Xenopus laevis embryogenesis. Based on the kinetics of the labeling, we concluded that the pattern of RNA synthesis in Xenopus embryogenesis changes following at least three characteristically different phases. The first phase is the pre-MBT stage, which is characterized by the synthesis of heterogeneous mRNA-like RNA, accompanied by the synthesis of small amounts of 4 S RNA, 5 S RNA and snRNAs. The second phase is the MBT stage which is characterized by a large activation (about 50-fold increase on a per cell basis) of 4 S RNA synthesis. The third phase is the post-MBT stage which is characterized by the commencement and increase in rRNA synthesis. We assume that RNA polymerases II, III and I are activated in this order in early Xenopus embryogenesis.
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Affiliation(s)
- K Shiokawa
- Laboratory of Developmental Biology, Faculty of Science, Kyushu University, Fukuoka, Japan
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Shiokawa K, Tashiro K, Nakakura N, Fu Y, Atsuchi Y, Nakazato S, Tsuzaki Y, Ikenishi K. A possible maternal-effect mutant of Xenopus laevis: II. Studies of RNA synthesis in dissociated embryonic cells. CELL DIFFERENTIATION AND DEVELOPMENT : THE OFFICIAL JOURNAL OF THE INTERNATIONAL SOCIETY OF DEVELOPMENTAL BIOLOGISTS 1988; 25:47-55. [PMID: 2461791 DOI: 10.1016/0922-3371(88)90054-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Embryos from a female of Xenopus laevis (designated as no. 65) arrest development at gastrulation and are assumed to be ova-deficient mutant. We dissociated these embryos and studied RNA synthesis at different stages. The cells from the ova-deficient embryos reaggregated quite actively as wild-type embryo cells until the late gastrula stage. RNA synthesis was normal at the early blastula stage but greatly inhibited by the late blastula (stage 9.5) stage, when the synthesis of DNA and protein was still not inhibited appreciably. Thus, inhibition in RNA synthesis appears to be the first manifestation of the maternal defect that occurs before the gastrulation arrest.
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Affiliation(s)
- K Shiokawa
- Department of Biology, Faculty of Science, Kyushu University, Fukuoka, Japan
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Etkin LD. Regulation of the mid-blastula transition in amphibians. DEVELOPMENTAL BIOLOGY (NEW YORK, N.Y. : 1985) 1988; 5:209-25. [PMID: 3077975 DOI: 10.1007/978-1-4615-6817-9_7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The cleavage cycles during early amphibian development are synchronous, rapid, and biphasic. There is no transcription and no growth of the embryo, and the nuclear cycle is independent of the cytoplasmic cleavage cycle. All components necessary for development through the blastula stage are provided by maternal stores. At the twelfth cleavage division, a major transition occurs that involves initiation of transcription, an elongation of the cell cycle, an increase in cell movement, and asynchrony of cell division. It is probable that the major controlling factor in the regulation of all the aforementioned events is the cell cycle. During early cleavage stages, the cell cycle is both rapid (30-35 min) and synchronous. There is evidence that the cycling time may be controlled by the presence of several mitotic factors, such as MPF, CSF (cytostatic factor), and a titratable component that binds to nuclear membranes. The rapid rate of DNA synthesis may inhibit the formation of transcription complexes, resulting in the absence of detectable transcription before the MBT. Cellular movement may also be inhibited in the rapidly dividing cell. As the cell cycle elongates (possibly due to the functional loss or sequestration of one or more of the mitotic control factors), the G1 and G2 phases are incorporated into the cell cycle. Under conditions of slower rates of DNA replication and the presence of the G1 and G2 phases, the transcriptional machinery becomes functional. It is apparent that at the MBT, not all classes of transcripts are activated simultaneously in every cell, nor is their expression regulated by a common mechanism. Incorporation of the G1 and G2 phases in the cell cycle may also permit the synthesis and assembly of microtubules and cytoskeletal components necessary for the initiation of the cell movements characteristic of this stage of development. The role of the cell cycle in controlling events at the MBT is supported by evidence from studies in which perturbation of the cell cycle that results in its elongation or arrest produces subsequent initiation of events that occur normally at the MBT. The MBT therefore appears to be a window in the developmental time frame, during which a number of molecular and morphogenetic events occur independently of one another, but all are necessary for subsequent morphogenesis and cellular differentiation. It is a transition from the strict reliance on the maternal program to a dependence on the new transcription from the embryonic genetic program. It is probable that the major regulatory mechanism involved in the occurrence of this constellation of cellular events is the change in the cell cycle.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- L D Etkin
- Department of Molecular Genetics, University of Texas Cancer Systems Center, M.D. Anderson Hospital and Tumor Institute, Houston 77030
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Berking S. Ammonia, tetraethylammonium, barium and amiloride induce metamorphosis in the marine hydroid Hydractinia. ACTA ACUST UNITED AC 1988; 197:1-9. [DOI: 10.1007/bf00376035] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/1987] [Accepted: 08/10/1987] [Indexed: 10/26/2022]
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Nakakura N, Miura T, Yamana K, Ito A, Shiokawa K. Synthesis of heterogeneous mRNA-like RNA and low-molecular-weight RNA before the midblastula transition in embryos of Xenopus laevis. Dev Biol 1987; 123:421-9. [PMID: 2443406 DOI: 10.1016/0012-1606(87)90400-3] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
It has been proposed and is now widely accepted that in Xenopus laevis embryogenesis RNA synthesis starts only at and after 12 rounds of cleavage, at the time of the midblastula transition (MBT). In this report, however, we provide evidence that RNA synthesis takes place prior to the MBT stage in normally developing Xenopus embryos. In the present experiments, we cultured fertilized eggs in 80 mM phosphate buffer and loosened the adhesion between blastomeres, so that [3H]uridine could be incorporated into blastomeres from the surrounding medium. By this method and also by microinjection of [3H]GTP, we found that embryos synthesize heterogeneous, nonribosomal, high-molecular-weight RNAs and a relatively small amount of low-molecular-weight RNA as early as the sixth cleavage. RNAs synthesized were not of mitochondrial origin, and the synthesis was sensitive to actinomycin D and alpha-amanitin. From these results we conclude that mRNA-like RNA and low-molecular-weight RNA start to be synthesized during the cleavage stage.
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Affiliation(s)
- N Nakakura
- Laboratory of Developmental Biology, Faculty of Science, Kyushu University, Fukuoka, Japan
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