An in vitro circadian rhythm of protein synthesis in the rat suprachiasmatic nucleus under tissue culture conditions

We review some of the problems in determining how myofibrils may be assembled and just as importantly how this contractile structure may be renewed by sarcomeric proteins moving between the sarcomere and the cytoplasm. We also address in this personal review the recent evidence that indicates that the assembly and dynamics of myofibrils are conserved whether the cells are analyzed in situ or in tissue culture conditions. We suggest that myofibrillogenesis is a fundamentally conserved process, comparable to protein synthesis, mitosis, or cytokinesis, whether examinedin situorin vitro.

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Protein-synthesis inhibitor blocks (R,S)-α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA)- or substance P-induced phase shift of the circadian rhythm of neuronal activity in the rat suprachiasmatic nucleus in vitro

Neuroscience Letters ◽

10.1016/0304-3940(94)90440-5 ◽

1994 ◽

Vol 168 (1-2) ◽

pp. 159-162 ◽

Cited By ~ 6

Author(s):

Shigenobu Shibata ◽

Akihito Watanabe ◽

Toshiyuki Hamada ◽

Shigenori Watanabe

Keyword(s):

Protein Synthesis ◽

Circadian Rhythm ◽

Substance P ◽

Phase Shift ◽

Propionic Acid ◽

Suprachiasmatic Nucleus ◽

Neuronal Activity ◽

Protein Synthesis Inhibitor ◽

Synthesis Inhibitor

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Myofibrillar degeneration with diphtheria toxin

Turkish Journal of Biochemistry ◽

10.1515/tjb-2019-0109 ◽

2020 ◽

Vol 45 (4) ◽

pp. 351-357

Author(s):

Bilge Özerman Edis ◽

Muhammet Bektaş ◽

Rüstem Nurten

Keyword(s):

Protein Synthesis ◽

Actin Filaments ◽

Diphtheria Toxin ◽

Cardiac Tissue ◽

Culture Conditions ◽

Bacterial Toxin ◽

Filamentous Actin ◽

Cardiac Damage ◽

Tissue Samples

AbstractObjectivesCardiac damage in patient with diphtheritic myocarditis is reported as the leading cause of mortality. Diphtheria toxin (DTx) is a well-known bacterial toxin inducing various cytotoxic effects. Mainly, catalytic fragment inhibits protein synthesis, induces cytotoxicity, and depolymerizes actin filaments. In this study, we aimed to demonstrate the extent of myofibrillar damage under DTx treatment to porcine cardiac tissue samples.MethodsTissue samples were incubated with DTx for 1–3 h in culture conditions. To analyze whole toxin (both fragments) distribution, conjugation of DTx with FITC was performed. Measurements were carried out with fluorescence spectrophotometer before and after dialysis. Immunofluorescence microscopy was used to show localization of DTx-FITC (15 nM) on cardiac tissue incubated for 2 h. Ultrastructural characterization of cardiac tissue samples treated with DTx (15 or 150 nM) was performed with transmission electron microscopy.ResultsDTx exerts myofibrillar disorganization. Myofilament degeneration, mitochondrial damage, vacuolization, and abundant lipid droplets were determined with 150 nM of DTx treatment.ConclusionsThis finding is an addition to depolymerization of actin filaments as a result of the DTx-actin interactions in in vitro conditions, indicating that myofilament damage can occur with DTx directly besides protein synthesis inhibition. Ultrastructural results support the importance of filamentous actin degeneration at diphtheritic myocarditis.

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Barley somatic embryogenesis-an attempt to modify variation induced in tissue culture

Journal of Biological Research-Thessaloniki ◽

10.1186/s40709-021-00138-5 ◽

2021 ◽

Vol 28 (1) ◽

Author(s):

Renata Orłowska

Keyword(s):

Tissue Culture ◽

Somatic Embryogenesis ◽

Taguchi Method ◽

Culture Conditions ◽

Dna Demethylation ◽

Silver Ion ◽

Donor Plant ◽

In Vitro Tissue Culture ◽

Induced Variation

Abstract Background Somatic embryogenesis is a phenomenon carried out in an environment that generates abiotic stress. Thus, regenerants may differ from the source of explants at the morphological, genetic, and epigenetic levels. The DNA changes may be the outcome of induction media ingredients (i.e., copper and silver ions) and their concentrations and time of in vitro cultures. Results This study optimised the level of copper and silver ion concentration in culture media parallel with the induction medium longevity step towards obtaining barley regenerants via somatic embryogenesis with a minimum or maximum level of tissue culture-induced differences between the donor plant and its regenerants. The optimisation process is based on tissue culture-induced variation evaluated via the metAFLP approach for regenerants derived under varying in vitro tissue culture conditions and exploited by the Taguchi method. In the optimisation and verification experiments, various copper and silver ion concentrations and the different number of days differentiated the tested trials concerning the tissue culture-induced variation level, DNA demethylation, and de novo methylation, including symmetric (CG, CHG) and asymmetric (CHH) DNA sequence contexts. Verification of optimised conditions towards obtaining regenerants with minimum and maximum variability compared to donor plants proved useful. The main changes that discriminate optimised conditions belonged to DNA demethylation events with particular stress on CHG context. Conclusions The combination of tissue culture-induced variation evaluated for eight experimental trials and implementation of the Taguchi method allowed the optimisation of the in vitro tissue culture conditions towards the minimum and maximum differences between a source of tissue explants (donor plant) and its regenerants from somatic embryos. The tissue culture-induced variation characteristic is mostly affected by demethylation with preferences towards CHG sequence context.

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The effect of osmolarity on mouse parthenogenesis

Development ◽

10.1242/dev.31.2.513 ◽

1974 ◽

Vol 31 (2) ◽

pp. 513-526

Author(s):

M. H. Kaufman ◽

M. A. H. Surani

Keyword(s):

Protein Synthesis ◽

Culture Medium ◽

Culture Media ◽

Polar Body ◽

Amino Acid Mixture ◽

Culture Conditions ◽

Follicle Cells ◽

Acid Mixture ◽

Second Polar Body

Eggs from (C57B1 × A2G)F1 mice were activated by treatment with hyaluronidase, which removed the follicle cells, and cultured in vitro. Observations were made 6–8 h after hyaluronidase treatment to determine the frequency of activation and the types of parthenogenones induced. Cumulus-free eggs resulting from hyaluronidase treatment were incubated for 2¼ h in culture media of various osmolarities. The frequency of activation was found to be dependent on the postovulatory age of oocytes, while the types of parthenogenones induced were dependent on the osmolarity of the in vitro culture medium and their postovulatory age. Culture in low osmolar medium suppressed the extrusion of the second polar body (2PB). This decreased the incidence of haploid eggs with a single pronucleus and 2PB and immediately cleaved eggs from 97·5% to 42·3% of the activated population. Where 2PB extrusion had been suppressed, 97·4% of parthenogenones contained two haploid pronuclei. Very few were observed with a single and presumably diploid pronucleus. Serial observations from 11 to 18 h after hyaluronidase treatment were made on populations of activated eggs as they entered the first cleavage mitosis after 2¼ h incubation in medium either of normal (0·287 osmol) or low (0·168 osmol) osmolarity. A delay in the time of entry into the first cleavage mitosis similar to the duration of incubation in low osmolar medium was observed. Further, eggs were incubated in control and low osmolar culture media containing uniformly labelled [U-14C]amino acid mixture to examine the extent of protein synthesis in recently activated eggs subjected to these culture conditions. An hypothesis is presented to explain the effect of incubation in low osmolar culture medium in delaying the first cleavage mitosis.

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