Cortical positioning and the fate of oral structures during the sexual process in amicronucleate homopolar tandems of Paramecium

Development ◽  
1988 ◽  
Vol 102 (3) ◽  
pp. 587-594
Author(s):  
S.F. Ng
Keyword(s):  
Sexual Reproduction ◽  
Cell Lines ◽  
Low Frequency ◽  
Positional Information ◽  
Binary Fission ◽  
Transient Growth ◽  
Paramecium Tetraurelia ◽  
Growth Depression ◽  
Sexual Process

Paramecium tetraurelia normally resorbs the pre-existing oral apparatus (and develops a new one) during sexual reproduction. Violation of this rule was found in amicronucleate cell lines. These cell lines generated chains of two cells (homopolar tandems) at a low frequency, as a result of incomplete binary fission during a transient growth depression period following emicronucleation. In autogamous chains, the proter resorbed the pre-existing oral structures, while some of the ospisthes retained them. The oral structures in the opisthes of the chains were unusually close to the opisthes' anterior end. The ectopic location of these oral structures might account for their retention, formally understood in terms of the theory of positional information. It is suggested that nongenic factors, likely involving components of the rigid cortical matrix, are involved in the fixation of positional values.

5-Azacytidine affects the programming of expression of the somatic nucleus of Paramecium

Development ◽  
1989 ◽  
Vol 105 (3) ◽  
pp. 559-568 ◽  
Author(s):  
F.W. Kwok ◽  
S.F. Ng
Keyword(s):  
Sexual Reproduction ◽  
Cell Lines ◽  
Compensatory Mechanism ◽  
Paramecium Tetraurelia ◽  
Growth Depression ◽  
Somatic Nucleus ◽  
Asexual Propagation ◽  
Oral Development ◽  
Asexual Cycle

This report introduces a new system in the study of programming of genomic function during development of the somatic nucleus of Paramecium tetraurelia. Previous works have established a definite, but replaceable, role of the germ nuclei (micronuclei) in oral development in the asexual cycle; their removal from the cell generates viable amicronucleate cell lines, which characteristically suffer a transient period of growth depression marked by abnormal oral development. Such cell lines gradually recover, showing that a compensatory mechanism is activated in the absence of the germ nuclei to bring the cell back to near-normal. To test the notion that the somatic nucleus (macronucleus) is involved in this compensation, cells possessing micronuclei were treated with 5-azacytidine during sexual reproduction when new somatic nuclei develop. These cells were then propagated asexually for a number of fissions in the absence of the drug, and thereafter micronuclei were removed from them. The amicronucleate cell lines generated in this manner clearly did not suffer a depression as severe as the untreated controls did in terms of growth rate and oral development, and they recovered much sooner. This supports the notion that the somatic nucleus is the physical basis of the compensatory mechanism. This study suggests that the stomatogenic sequences in question normally become repressed in the somatic nucleus developing in sexual reproduction, and that 5-azacytidine administered to the cells at this time could alter this programme which then persists during subsequent asexual propagation. The possibility that the somatic nucleus is programmed by methylation of cytosine at the 5′ position is discussed.

The rescue of oral development of defective-micronucleate conjugants of Paramecium tetraurelia by normal gametic nuclei

1988 ◽  
Vol 90 (2) ◽  
pp. 287-293
Author(s):  
M. F. CHAU ◽  
STEPHEN F. NG
Keyword(s):  
Sexual Reproduction ◽  
Cell Lines ◽  
Early Stage ◽  
Sexual Cycle ◽  
Paramecium Tetraurelia ◽  
Laser Microbeam ◽  
Nuclear Reorganization ◽  
Oral Development ◽  
Derivatives Of

The present study further analyses the importance of postmeiotic divisional derivatives of the micronucleus in the development of the oral apparatus of Paramecium during sexual reproduction. Cell lines possessing defective micronuclei generated by laser microbeam irradiation of the micronucleus were employed. They exhibited anomalies in nuclear reorganization and stomatogenesis in the sexual cycle. During autogamy, in some cells the micronuclear cycle terminated shortly after meiosis, resulting in the loss of all postmeiotic micronuclear derivatives. Stomatogenesis became arrested at an early stage of assembly of the oral membranelles, but the old oral apparatus was resorbed as usual, leading to the production of astomatous cells at the end of the sexual cycle. Conjugation of these cell lines with normal micronucleates rescued both nucleogenesis and stomatogenesis in the defective micronucleate conjugant, primarily as a result of transfer of the male gametic nucleus from the normal conjugant to the defective-micronucleate mate. These observations demonstrate the stomatogenic significance, in particular in the initiation of oral membranelle assembly, of the gametic nuclei during sexual reproduction. The present study also suggests the possibility of micronuclear activities in the early part of the sexual cycle affecting postzygotic nucleogenesis.

The somatic function of the micronucleus in sexual reproduction of Paramecium tetraurelia: initiation of oral membranelle assembly

1988 ◽  
Vol 90 (1) ◽  
pp. 157-166
Author(s):  
M. F. CHAU ◽  
STEPHEN F. NG
Keyword(s):  
Sexual Reproduction ◽  
Laser Irradiation ◽  
Cell Lines ◽  
Paramecium Tetraurelia ◽  
Laser Microbeam ◽  
Microbeam Irradiation ◽  
Nuclear Reorganization

In a previous study, cell lines possessing defective micronuclei, generated by laser-microbeam irradiation, gave rise to cells lacking both oral apparatus and micronuclear derivatives after autogamy. It was concluded that astomy arose as a result of degeneration of all of the meiotic products of the micronuclei after meiotic telophase II, instead of leaving one product for subsequent nuclear reorganization. The present study consolidates this conclusion by employing 15 micronucleus-defective cell lines; these were generated by laser-irradiation of the micronucleus, treatment of the cells with cis-dichlorodiamineplatinum (II), and conjugation between diploids and amicronucleates to produce haploids. A good correlation between the presence of pregametic, gametic and zygotic nuclei and the initiation of oral membranelle assembly in stomatogenesis was demonstrated in 17 cases of autogamy. Therefore, postmeiotic micronuclear activities up to the zygotic nucleus stage, in particular in the gametic stage, are crucial for the initiation of oral membranelle assembly, while premeiotic micronuclear activities are insufficient. Micronuclear genic factors are also likely to be involved in the determination of the fate of the meiotic products.

scholarly journals The Influence of the Extremely Low Frequency Electromagnetic Field on Clear Cell Renal Carcinoma

2021 ◽  
Vol 22 (3) ◽  
pp. 1342
Author(s):  
Aleksandra Cios ◽  
Martyna Ciepielak ◽  
Wanda Stankiewicz ◽  
Łukasz Szymański
Keyword(s):  
Electromagnetic Field ◽  
Cancer Cells ◽  
Cell Lines ◽  
Renal Carcinoma ◽  
Clear Cell ◽  
Low Frequency ◽  
Inhibitory Effect ◽  
Hek293 Cells ◽  
Clear Cell Renal Carcinoma ◽  
Cell Renal Carcinoma

The development of new technologies and industry is conducive to the increase in the number and variety of electromagnetic field (EMF) sources in our environment. The main sources of EMF are high-voltage lines, household appliances, audio/video devices, mobile phones, radio stations, and radar devices. In the growing use of electronic devices, scientists are increasingly interested in the effects of EMF on human health. Even though many studies on the effects of EMF have already been carried out, none of them has shown a significant effect on mammals, including humans. Moreover, it is not entirely clear how EMF influences cell behavior. The International Agency for Research on Cancer on 31 May 2011, classified PEM as a possible carcinogenic factor. This study aimed to investigate the effect of the electromagnetic field on morphological and functional changes in clear cell renal carcinoma. The research was carried out on in vitro cultures of four cell lines: HEK293, 786-O 769-P, and Caki1. The results of the research showed that the EMF of low frequency had a slight effect on the viability of cells. EMF, which induced cell arrest in the G1 phase, increased the number of early apoptotic cells and decreased the number of viable cells in the 786-O line. EMF did not affect the proliferation and viability of HEK293 cells. Extreme low-frequency EMF (ELF-EMF) also showed an inhibitory effect on the migration and metastatic properties of clear cell kidney cancer cells. Moreover, shortly after the end of ELF-EMF exposure, significant increases in ROS levels were observed in all tested cell lines. As part of the work, it was shown that low-frequency EMF shows an inhibitory effect on the proliferation of primary cancer cells, diminishing their migratory, invasive, and metastatic abilities. It also increases the apoptosis of cancer cells and the amount of reactive oxygen species. Based on the results of our research, we want to point up that the effect of ELF-EMF depends on a specific metabolic state or at a specific stage in the cell cycle of the cells under study.

The Ets-related transcription factor PU.1 immortalizes erythroblasts

1993 ◽  
Vol 13 (9) ◽  
pp. 5670-5678
Author(s):  
S Schuetze ◽  
P E Stenberg ◽  
D Kabat
Keyword(s):  
Bone Marrow ◽  
Transcription Factor ◽  
Cell Lines ◽  
Cultured Cells ◽  
Low Frequency ◽  
In Vivo Studies ◽  
Bone Marrow Cultures ◽  
Clonal Cell Lines ◽  
Related Transcription Factor

In vivo studies of Friend virus erythroleukemia have implied that proviral integrations adjacent to the gene for the Ets-related transcription factor PU.1 may inhibit the commitment of erythroblasts to differentiate and cause their capability for indefinite transplantation (C. Spiro, B. Gliniak, and D. Kabat, J. Virol. 62:4129-4135, 1988; R. Paul, S. Schuetze, S. L. Kozak, C. Kozak, and D. Kabat, J. Virol. 65:464-467, 1991). To test this hypothesis, we ligated PU.1 cDNA into a retroviral vector and studied its effects on cultured cells. Infection of fibroblasts with PU.1-encoding retrovirus resulted in PU.1 synthesis followed by nuclear pyknosis, cell rounding, and degeneration. In contrast, in long-term bone marrow cultures, erythroblasts were efficiently and rapidly immortalized. The resulting cell lines were polyclonal populations that contained PU.1, were morphologically blast-like, required erythropoietin and bone marrow stromal cells for survival and proliferation, and spontaneously differentiated at low frequency to synthesize hemoglobin. After 9 months in culture, erythroblasts became stroma independent, and they then grew as clonal cell lines. We conclude that PU.1 perturbs the pathway(s) that controls potential for indefinite proliferation and that it can be used to generate permanent erythroblast cell lines.

Mutation at autosomal loci of Chinese hamster ovary cells: involvement of a high-frequency event silencing two linked alleles

1983 ◽  
Vol 3 (7) ◽  
pp. 1172-1181
Author(s):  
W E Bradley
Keyword(s):  
Cell Lines ◽  
Chinese Hamster Ovary ◽  
High Frequency ◽  
Chinese Hamster Ovary Cells ◽  
Chinese Hamster ◽  
Low Frequency ◽  
Class Ii ◽  
Class I ◽  
Wild Type ◽  
Ovary Cells

Two classes of cell lines heterozygous at the galactokinase (glk) locus have been isolated from Chinese hamster ovary cells. Class I, selected by plating nonmutagenized wild-type cells at low density in medium containing 2-deoxygalactose at a partially selective concentration, underwent subsequent mutation to the glk-/- genotype at a low frequency (approximately 10(-6) per cell), which was increased by mutagenesis. Class II heterozygotes, isolated by sib selection from mutagenized wild-type cells, had a higher spontaneous frequency of mutation to the homozygous state (approximately 10(-4) per cell), which was not affected by mutagenesis. About half of the glk-/- mutants derived from a class II heterozygote, but not the heterozygote itself, were functionally hemizygous at the syntenic thymidine kinase (tk) locus. Similarly, a tk+/- heterozygote with characteristics analogous to the class II glk+/- cell lines underwent high-frequency mutation to tk-/-, and most of these mutants, but not the tk+/- heterozygote, were functionally hemizygous at the glk locus. A model is proposed, similar to that for the mutational events at the adenine phosphoribosyl transferase locus (W. E. C. Bradley and D. Letovanec, Somatic Cell Genet. 8:51-66, 1982), of two different events, high and low frequency, being responsible for mutation at either of the linked loci tk and glk. The low-frequency event may be a point mutation, but the high-frequency event, in many instances, involves coordinated inactivation of a portion of a chromosome carrying the two linked alleles. Class II heterozygotes would be generated as a result of a low-frequency event at one allele, and class I heterozygotes would be generated by a high-frequency event. Supporting this model was the demonstration that all class I glk+/- lines examined were functionally hemizygous at tk.

scholarly journals The Ets-related transcription factor PU.1 immortalizes erythroblasts.

1993 ◽  
Vol 13 (9) ◽  
pp. 5670-5678 ◽  
Author(s):  
S Schuetze ◽  
P E Stenberg ◽  
D Kabat
Keyword(s):  
Bone Marrow ◽  
Transcription Factor ◽  
Cell Lines ◽  
Cultured Cells ◽  
Low Frequency ◽  
In Vivo Studies ◽  
Bone Marrow Cultures ◽  
Clonal Cell Lines ◽  
Related Transcription Factor

In vivo studies of Friend virus erythroleukemia have implied that proviral integrations adjacent to the gene for the Ets-related transcription factor PU.1 may inhibit the commitment of erythroblasts to differentiate and cause their capability for indefinite transplantation (C. Spiro, B. Gliniak, and D. Kabat, J. Virol. 62:4129-4135, 1988; R. Paul, S. Schuetze, S. L. Kozak, C. Kozak, and D. Kabat, J. Virol. 65:464-467, 1991). To test this hypothesis, we ligated PU.1 cDNA into a retroviral vector and studied its effects on cultured cells. Infection of fibroblasts with PU.1-encoding retrovirus resulted in PU.1 synthesis followed by nuclear pyknosis, cell rounding, and degeneration. In contrast, in long-term bone marrow cultures, erythroblasts were efficiently and rapidly immortalized. The resulting cell lines were polyclonal populations that contained PU.1, were morphologically blast-like, required erythropoietin and bone marrow stromal cells for survival and proliferation, and spontaneously differentiated at low frequency to synthesize hemoglobin. After 9 months in culture, erythroblasts became stroma independent, and they then grew as clonal cell lines. We conclude that PU.1 perturbs the pathway(s) that controls potential for indefinite proliferation and that it can be used to generate permanent erythroblast cell lines.

scholarly journals Delivery of low intensity/low frequency electric fields via clinical Deep Brain Stimulation electrodes has anti-proliferative effects on Glioblastoma multiforme cell lines

2018 ◽  
Vol 20 (suppl_1) ◽  
pp. i11-i11
Author(s):  
Joshua Branter ◽  
Maria de los Angeles Estevez-Cebrero ◽  
Richard Grundy ◽  
Surajit Basu ◽  
Stuart Smith
Keyword(s):  
Deep Brain Stimulation ◽  
Glioblastoma Multiforme ◽  
Cell Lines ◽  
Electric Fields ◽  
Brain Stimulation ◽  
Low Frequency ◽  
Low Intensity ◽  
Deep Brain

scholarly journals Lack of hotspot mutations other than TP53 R249S in aflatoxin B1 associated hepatocellular carcinoma

2020 ◽  
Vol 45 (4) ◽  
pp. 451-453
Author(s):  
Cemaliye B. Akyerli ◽  
Şirin K. Yüksel ◽  
M. Cengiz Yakıcıer
Keyword(s):  
Hepatocellular Carcinoma ◽  
Cell Line ◽  
Cell Lines ◽  
Aflatoxin B1 ◽  
Low Frequency ◽  
Gene Mutations ◽  
Pathogenic Mutation ◽  
Liver Carcinoma ◽  
Major Health Problem ◽  
Hotspot Mutations

AbstractObjectiveDespite the recent advances in diagnosis and treatment of hepatocellular carcinoma (HCC), it is still a major health problem. Therefore, understanding the molecular mechanism is very important. Our aim is to investigate the molecular basis of aflatoxin B1 (AFB1) induced HCC other than the hotspot TP53 p.Arg249Ser (c.747G>T) (R249S) mutation.Methods525 genes previously reported to be involved in carcinogenesis with mutations in different cancer types were analyzed by next generation sequencing for 525 cancer-gene panel (Roche/NimbleGen) in one tumor sample (T29) and one cell line (MAHLAVU) carrying TP53 R249S mutation. Additionally, ARID2 and BCORL1 genes were analyzed by Sanger sequencing for MAHLAVU and Primary Liver Carcinoma/Poliomyelitis Research Foundation/5 (PLC/PRF/5) cell lines.ResultsNo other common gene mutations were found in the analyzed T29 and MAHLAVU samples and also no genetic variation possibly associated with AFB1 was detected in PLC/PRF/5 cell line and 68 COSMIC HCC samples. Likewise, no pathogenic mutation was detected in ARID2 and BCORL1 genes of MAHLAVU and PLC/PRF/5 cell lines.ConclusionNo fingerprint mutations were detected in the analyzed genes. To the best of our knowledge, other hotspot mutations appear to be absent if not at a very low frequency in HCC carrying TP53 R249S mutation.

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