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Krüger J, Richter P, Stoltze J, Strauch SM, Krüger M, Daiker V, Prasad B, Sonnewald S, Reid S, Lebert M. Changes of Gene Expression in Euglena gracilis Obtained During the 29 th DLR Parabolic Flight Campaign. Sci Rep 2019; 9:14260. [PMID: 31582787 PMCID: PMC6776534 DOI: 10.1038/s41598-019-50611-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 09/02/2019] [Indexed: 01/14/2023] Open
Abstract
Parabolic flight maneuvers of Novespace's Airbus A310 ZERO-G produce subsequent phases of hypergravity (about 20 s), microgravity (about 22 s) and another 20 s hypergravity on experiments located in the experiment area of the aircraft. The 29th DLR parabolic flight campaign consisted of four consecutive flight days with thirty-one parabolas each day. Euglena gracilis cells were fixed with TRIzol during different acceleration conditions at the first and the last parabola of each flight. Samples were collected and analyzed with microarrays for one-color gene expression analysis. The data indicate significant changes in gene expression in E. gracilis within short time. Hierarchical clustering shows that changes induced by the different accelerations yield reproducible effects at independent flight days. Transcription differed between the first and last parabolas indicating adaptation effects in the course of the flight. Different gene groups were found to be affected in different phases of the parabolic flight, among others, genes involved in signal transduction, calcium signaling, transport mechanisms, metabolic pathways, and stress-response as well as membrane and cytoskeletal proteins. In addition, transcripts of other areas, e.g., DNA and protein modification, were altered. The study contributes to the understanding of short-term effects of microgravity and different accelerations on cells at a molecular level.
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Affiliation(s)
- Julia Krüger
- Cell Biology Division: Gravitational Biology Group, Department of Biology, Friedrich-Alexander University Erlangen-Nürnberg, Staudtstraße 5, 91058, Erlangen, Germany
| | - Peter Richter
- Cell Biology Division: Gravitational Biology Group, Department of Biology, Friedrich-Alexander University Erlangen-Nürnberg, Staudtstraße 5, 91058, Erlangen, Germany
| | - Julia Stoltze
- Cell Biology Division: Gravitational Biology Group, Department of Biology, Friedrich-Alexander University Erlangen-Nürnberg, Staudtstraße 5, 91058, Erlangen, Germany
| | - Sebastian M Strauch
- Cell Biology Division: Gravitational Biology Group, Department of Biology, Friedrich-Alexander University Erlangen-Nürnberg, Staudtstraße 5, 91058, Erlangen, Germany
- Postgraduate Program in Health and Environment, University of Joinville Region, Rua Paulo Malschitzki, 10 - Zona Industrial Norte, Joinville, SC, CEP 89219-710, Brazil
| | - Marcus Krüger
- Clinic for Plastic, Aesthetic and Hand Surgery, Otto von Guericke University Magdeburg, Leipziger Straße 44, 39120, Magdeburg, Germany
| | - Viktor Daiker
- Cell Biology Division: Gravitational Biology Group, Department of Biology, Friedrich-Alexander University Erlangen-Nürnberg, Staudtstraße 5, 91058, Erlangen, Germany
| | - Binod Prasad
- Cell Biology Division: Gravitational Biology Group, Department of Biology, Friedrich-Alexander University Erlangen-Nürnberg, Staudtstraße 5, 91058, Erlangen, Germany
| | - Sophia Sonnewald
- Biochemistry Division, Department of Biology, Friedrich-Alexander University Erlangen-Nürnberg, Staudtstraße 5, 91058, Erlangen, Germany
| | - Stephen Reid
- Biochemistry Division, Department of Biology, Friedrich-Alexander University Erlangen-Nürnberg, Staudtstraße 5, 91058, Erlangen, Germany
| | - Michael Lebert
- Cell Biology Division: Gravitational Biology Group, Department of Biology, Friedrich-Alexander University Erlangen-Nürnberg, Staudtstraße 5, 91058, Erlangen, Germany.
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Nasir A, Strauch SM, Becker I, Sperling A, Schuster M, Richter PR, Weißkopf M, Ntefidou M, Daiker V, An YA, Li XY, Liu YD, Lebert M. The influence of microgravity on Euglena gracilis as studied on Shenzhou 8. PLANT BIOLOGY (STUTTGART, GERMANY) 2014; 16 Suppl 1:113-119. [PMID: 23926886 DOI: 10.1111/plb.12067] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Accepted: 05/31/2013] [Indexed: 06/02/2023]
Abstract
The German Aerospace Center (DLR) enabled German participation in the joint space campaign on the unmanned Shenzhou 8 spacecraft in November 2011. In this report, the effect of microgravity on Euglena gracilis cells is described. Custom-made dual compartment cell fixation units (containing cells in one chamber and fixative - RNA lysis buffer - in another one) were enclosed in a small container and placed in the Simbox incubator, which is an experiment support system. Cells were fixed by injecting them with fixative at different time intervals. In addition to stationary experiment slots, Simbox provides a 1 g reference centrifuge. Cell fixation units were mounted in microgravity and 1 g reference positions of Simbox. Two Simbox incubators were used, one for space flight and the other as ground reference. Cells were fixed soon after launch and shortly before return of the spaceship. Due to technical problems, only early in-flight samples (about 40 min after launch microgravity and corresponding 1 g reference) were fully mixed with fixative, therefore only data from those samples are presented. Transcription of several genes involved in signal transduction, oxidative stress defence, cell cycle regulation and heat shock responses was investigated with quantitative PCR. The data indicate that Euglena cells suffer stress upon short-term exposure to microgravity; various stress-induced genes were up-regulated. Of 32 tested genes, 18 were up-regulated, one down-regulated and the rest remained unaltered. These findings are in a good agreement with results from other research groups using other organisms.
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Affiliation(s)
- A Nasir
- Department of Biology, Cell Biology Division, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, Germany
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Daiker V, Lebert M, Richter P, Häder DP. Molecular characterization of a calmodulin involved in the signal transduction chain of gravitaxis in Euglena gracilis. PLANTA 2010; 231:1229-1236. [PMID: 20213123 DOI: 10.1007/s00425-010-1126-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2009] [Accepted: 02/10/2010] [Indexed: 05/28/2023]
Abstract
The unicellular flagellate Euglena gracilis shows a negative gravitactic behavior. This is based on physiological mechanisms which in the past have been indirectly assessed. Meanwhile, it was possible to isolate genes involved in the signal transduction chain of gravitaxis. The DNA sequences of five calmodulins were found in Euglena, one of which was only known in its protein structure (CaM.1); the other four are new. The biosynthesis of the corresponding proteins of CaM.1-CaM.5 was inhibited by means of RNA interference to determine their involvement in the gravitactic signal transduction chain. RNAi of CaM.1 inhibits free swimming of the cells and pronounced cell-form aberrations. The division of cells was also hampered. After recovery from RNAi the cell showed precise negative gravitaxis again. Blockage of CaM.3 to CaM. 5 did not impair gravitaxis. In contrast, the blockage of CaM.2 has only a transient and not pronounced influence on motility and cell form, but leads to a total loss of gravitactic orientation for more than 30 days. This indicates that CaM.2 is an element in the signal transduction chain of gravitaxis in E. gracilis. The results are discussed with regard to the current working model of gravitaxis in E. gracilis.
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Affiliation(s)
- Viktor Daiker
- Department of Biology, Plant Ecophysiology, Friedrich-Alexander University, Erlangen, Germany
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Ishikawa T, Nishikawa H, Gao Y, Sawa Y, Shibata H, Yabuta Y, Maruta T, Shigeoka S. The pathway via D-galacturonate/L-galactonate is significant for ascorbate biosynthesis in Euglena gracilis: identification and functional characterization of aldonolactonase. J Biol Chem 2008; 283:31133-41. [PMID: 18782759 PMCID: PMC2662179 DOI: 10.1074/jbc.m803930200] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2008] [Revised: 08/05/2008] [Indexed: 11/06/2022] Open
Abstract
We have previously proposed that Euglena gracilis possesses a pathway for the production of ascorbate (AsA) through d-galacturonate/L-galactonate as representative intermediates ( Shigeoka, S., Nakano, Y., and Kitaoka, S. (1979) J. Nutr. Sci. Vitaminol. 25, 299-307 ). However, genetic evidence proving that the pathway exists has not been obtained yet. We report here the identification of a gene encoding aldonolactonase, which catalyzes a penultimate step of the biosynthesis of AsA in Euglena. By a BLAST search, we identified one candidate for the enzyme having significant sequence identity with rat gluconolactonase, a key enzyme for the production of AsA via d-glucuronate in animals. The purified recombinant aldonolactonase expressed in Escherichia coli catalyzed the reversible reaction of L-galactonate and L-galactono-1,4-lactone with zinc ion as a cofactor. The apparent K(m) values for L-galactonate and L-galactono-1,4-lactone were 1.55 +/- 0.3 and 1.67 +/- 0.39 mm, respectively. The cell growth of Euglena was arrested by silencing the expression of aldonolactonase through RNA interference and then restored to the normal state by supplementation with L-galactono-1,4-lactone. Euglena cells accumulated more AsA on supplementation with d-galacturonate than d-glucuronate. The present results indicate that aldonolactonase is significant for the biosynthesis of AsA in Euglena cells, which predominantly utilize the pathwayviad-galacturonate/L-galactonate. The identification of aldonolactonase provides the first insight into the biosynthesis of AsA via uronic acids as the intermediate in photosynthetic algae including Euglena.
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Affiliation(s)
- Takahiro Ishikawa
- Faculty of Life and Environmental Science, Shimane University, Matsue, Shimane 690-8504, Japan.
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5
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p38 MAPK as a signal transduction component of heavy metals stress in Euglena gracilis. Arch Microbiol 2008; 191:47-54. [DOI: 10.1007/s00203-008-0427-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2008] [Revised: 08/05/2008] [Accepted: 08/18/2008] [Indexed: 10/21/2022]
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6
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Rensing L, Kallies A, Gebauer G, Mohsenzadeh S. The effects of temperature change on the circadian clock of Neurospora. CIBA FOUNDATION SYMPOSIUM 2007; 183:26-41; discussion 41-50. [PMID: 7656690 DOI: 10.1002/9780470514597.ch3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The phase resetting of the circadian oscillatory system by pulses of increased temperature (zeitgebers) and the temperature compensation of its period length during longer exposures are major features of the system, but are not well understood in molecular terms. In Neurospora crassa, the effects of pulses of increased temperature on the circadian rhythm of conidiation were determined and possible inputs to the oscillatory system tested, including changes in cyclic 3',5'-adenosine monophosphate (cAMP), inositol 1,4,5-trisphosphate and H+ concentrations, as well as changes of phosphorylation, synthesis and degradation of proteins. Following the kinetics of these parameters during exposure to increased temperature showed transient changes. Experimental manipulation of cAMP, Ca2+ and H+ levels, and of the synthesis and, possibly, degradation of proteins, resulted in phase shifts of the oscillatory system. It is assumed that the temperature signal affects the oscillator(s) by multiple pathways and shifts the whole state of the oscillatory system. Second messenger levels, protein synthesis and protein degradation show adaptation to longer exposures to elevated temperature which may be involved in the temperature compensation of the period length. The temperature compensation is also proposed to involve a shift in the state of all or most oscillator variables.
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Affiliation(s)
- L Rensing
- Department of Biology, University of Bremen, Germany
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7
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Wang GQ, Du YZ, Tong J. Daily oscillation and photoresponses of clock gene, Clock, and clock-associated gene, arylalkylamine N-acetyltransferase gene transcriptions in the rat pineal gland. Chronobiol Int 2007; 24:9-20. [PMID: 17364576 DOI: 10.1080/07420520601139821] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
This study was conducted to investigate the circadian rhythms and light responses of Clock and arylalkylamine N-acetyltransferase (NAT) gene expressions in the rat pineal gland under the environmental conditions of a 12 h light (05:00-17:00 h): 12 h-dark (17:00-05:00 h) cycle (LD) and constant darkness (DD). The pineal gland of Sprague-Dawley rats housed under a LD regime (n=42) for four weeks and of a regime (n=42) for eight weeks were sampled at six different times, every 4 h (n=7 animals per time point), during a 24 h period. Total RNA was extracted from each sample, and the semiquantitative reverse transcription polymerase chain reaction (RT-PCR) was used to determine temporal changes in mRNA levels of Clock and NAT genes during different circadian or zeitgeber times. The data and parameters were analyzed by the cosine function software, Clock Lab software, and the amplitude F test was used to reveal the circadian rhythm. In the DD or LD condition, both the Clock and NAT mRNA levels in the pineal gland showed robust circadian oscillation (p<0.05) with the peak at the subjective night or at nighttime. In comparison with the DD regime, the amplitudes and mRNA levels at the peaks of Clock and NAT expressions in LD in the pineal gland were significantly reduced (p<0.05). In the DD or LD condition, the circadian expressions of NAT were similar in pattern to those of Clock in the pineal gland (p>0.05). These findings indicate that the transcriptions of Clock and NAT genes in the pineal gland not only show remarkably synchronous endogenous circadian rhythmic changes, but also respond to the ambient light signal in a reduced manner.
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Affiliation(s)
- Guo-Qing Wang
- Department of Physiology, Medical School, Soochow University, Suzhou 215123, Jiangsu, China
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Richter PR, Schuster M, Lebert M, Hader DP. Gravitactic signal transduction elements in Astasia longa investigated during parabolic flights. MICROGRAVITY SCIENCE AND TECHNOLOGY 2003; 14:17-24. [PMID: 14658453 DOI: 10.1007/bf02870940] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Euglena gracilis and its close relative Astasia longa show a pronounced negative gravitactic behavior. Many experiments revealed that gravitaxis is most likely mediated by an active physiological mechanism. The goal of the present study was to examine elements in the sensory transduction by means of inhibitors of gravitaxis and the intracellular calcium concentration during short microgravity periods. During the course of six parabolic flights (ESA 31th parabolic flight campaign and DLR 6th parabolic flight campaign) the effects of trifluoperazine (calmodulin inhibitor), caffeine (phosphodiesterase inhibitor) and gadolinium (blocks mechano-sensitive ion channels) was investigated. Due to the extreme parabolic flight maneuvers of the aircraft alternating phases of 1.8 x g(n) (about 20 s) and microgravity (about 22 s) were achieved (g(n): acceleration of Earth's gravity field). The duration of the microgravity periods was sufficient to detect a loss of cell orientation in the samples. In the presence of gadolinium impaired gravitaxis was found during acceleration, while caffeine-treated cells showed, compared to the controls, a very precise gravitaxis and faster reorientation in the 1.8 x g(n) period following microgravity. A transient increase of the intracellular calcium upon increased acceleration was detected also in inhibitor-treated samples. Additionally, it was found that the cells showed a higher calcium signal when they deviated from the vertical swimming direction. In the presence of trifluoperazine a slightly higher general calcium signal was detected compared to untreated controls, while gadolinium was found to decrease the intracellular calcium concentration. In the presence of caffeine no clear changes of intracellular calcium were detected compared to the control.
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9
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Hader DP, Lebert M, Richter P, Ntefidou M. Gravitaxis and graviperception in flagellates. ADVANCES IN SPACE RESEARCH : THE OFFICIAL JOURNAL OF THE COMMITTEE ON SPACE RESEARCH (COSPAR) 2003; 31:2181-2186. [PMID: 14686430 DOI: 10.1016/s0273-1177(03)00242-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
There is strong evidence that gravitactic orientation in flagellates and ciliates is mediated by an active physiological gravireceptor rather than by passive alignment of the cells in the water column. In flagellates the threshold for graviorientation was found to be at 0.12 x g on a slow rotating centrifuge during the IML-2 mission on the Shuttle Columbia and a subsequent parabolic rocket flight (TEXUS). During the IML-2 mission no adaptation to microgravity was observed over the duration of the space flight, while gravitaxis was lost in a terrestrial closed environmental system over the period of almost two years. Sedimenting statoliths are not likely to be involved in graviperception because of the small size of the cells and their rotation around the longitudinal axis during forward locomotion. Instead the whole cytoplasmic content of the cell, being heavier than the surrounding aqueous medium (1.05 g/ml), exerts a pressure on the lower membrane. This force activates stretch-sensitive calcium specific ion channels which can be inhibited by the addition of gadolinium which therefore abolishes gravitaxis. The channels seem to mainly allow calcium ions to pass since gravitaxis is blocked by the addition of the calcium ionophore A23187 and by vanadate which blocks the Ca-ATPase in the cytoplasmic membrane. Recently, a gene for a mechanosensitive channel, originally sequenced for Saccharomyces, was identified in Euglena by PCR. The increase in intracellular free calcium during reorientation can be visualized by the fluorophore Calcium Crimson using laser excitation and image intensification. This result was confirmed during recent parabolic flights. The gated calcium changes the membrane potential across the membrane which may be the trigger for the reorientation of the flagellum. cAMP plays a role as a secondary messenger. Photosynthetic flagellates are suitable candidates for life support systems since they absorb CO2 and produce oxygen. Preliminary experiments are discussed.
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Affiliation(s)
- D-P Hader
- Institut fur Botanik und Pharmazeutische Biologie der Friedrich-Alexander-Universitat, Erlangen, Germany.
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Chapter 11 Phototaxis of Euglena gracilis—flavins and pterins. COMPREHENSIVE SERIES IN PHOTOSCIENCES 2001. [DOI: 10.1016/s1568-461x(01)80015-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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11
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Bjarnason GA, Jordan R. Circadian variation of cell proliferation and cell cycle protein expression in man: clinical implications. PROGRESS IN CELL CYCLE RESEARCH 2000; 4:193-206. [PMID: 10740826 DOI: 10.1007/978-1-4615-4253-7_17] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Most physiological, biochemical and behavioural processes have been shown to vary in a regular and predictable periodic manner with respect to time. This review focuses on the circadian rhythm in cell proliferation in bone marrow and gut and how this is associated with a circadian expression of cell cycle proteins in human oral mucosa. The control of circadian rhythms by the suprachiasmatic nuclei and the evolving understanding of the genetic and molecular biology of the circadian clock is outlined. Finally, the potential clinical impact of chronobiology in cancer medicine is discussed.
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Affiliation(s)
- G A Bjarnason
- Division of Medical Oncology, Toronto-Sunnybrook Regional Cancer Centre, Ontario, Canada
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12
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Lebert M, Porst M, Hader DP. Circadian rhythm of gravitaxis in Euglena gracilis. JOURNAL OF PLANT PHYSIOLOGY 1999; 155:344-349. [PMID: 11542916 DOI: 10.1016/s0176-1617(99)80115-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Euglena gracilis, a unicellular, photosynthetic flagellate is a model system for environmentally controlled behavioral reactions. One pronounced reaction is the orientation with respect to gravity. In synchronized cultures with no cell growth a distinct circadian rhythm of negative gravitactic orientation could be observed. The main maximum of sensitivity was detected 5 h after the beginning of the subjective day, the main minimum 5 h before the beginning of the subjective day. Transferring synchronized cultures to continuous light resulted in an almost instantaneous loss of rhythmicity. In contrast, after transfer to permanent darkness cells exhibited a circadian rhythm with a progressive shortening of the period for more than 5 days. These findings are in contrast to the circadian rhythm of phototaxis in Euglena, where a free-running period of 24 h was observed. Parallel measurements of negative gravitactic orientation, velocity, cell shape as well as cAMP concentration in synchronized cultures revealed a circadian rhythm of all reactions. The results are discussed with regard to the possible role of cell shape and cAMP in gravitactic orientation.
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Affiliation(s)
- M Lebert
- Friedrich-Alexander-Universitat, Institut fur Botanik und Pharmazeutische Biologie, Erlangen
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13
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Zhdanova IV, Simmons M, Marcus JN, Busza AC, Leclair OU, Taylor JA. Nocturnal increase in plasma cGMP levels in humans. J Biol Rhythms 1999; 14:307-13. [PMID: 10447311 DOI: 10.1177/074873099129000722] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The circadian dynamics of responses to cyclic guanosine 3',5'-monophosphate (cGMP) in in vitro experiments and the stimulating effects of the pineal hormone melatonin on cGMP levels both in vitro and in vivo provoked an investigation into the diurnal pattern of occurrence of this second messenger in human plasma and its correlation with plasma melatonin levels. Plasma cGMP levels were measured in 9 normal human subjects who were over 50 years of age. Samples were obtained hourly through a 20-h period (11 a.m. to 7 a.m.) that included the subjects' habitual hours of nocturnal sleep; physical activity was kept to a minimum during the daylight hours. The area under the time-plasma cGMP concentration curve showed a significant increase during the period of nocturnal sleep compared to that observed during the period of daytime wakefulness. The individual temporal pattern of the nocturnal rise in plasma cGMP differed among the subjects; however, the initial increase typically was observed soon after bedtime. No significant correlation was observed between individual nocturnal plasma melatonin levels and cGMP levels.
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Affiliation(s)
- I V Zhdanova
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge 02139, USA
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14
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Mohabir G, Edmunds LN. Circadian clock regulation of the bimodal rhythm of cyclic AMP in wild-type Euglena. Cell Signal 1999; 11:143-7. [PMID: 10048792 DOI: 10.1016/s0898-6568(98)00046-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Cell-cycle traverse is associated with fluctuations in the cellular content of cAMP; artificial alterations of these levels phase-shift cell division in free-running cultures of achlorophyllous Euglena maintained in constant darkness (DD). The phase shifts observed, however, are only transient: the cell division rhythm rephases to that of unperturbed controls. This implies that the second messenger functions downstream of the circadian oscillator. Further, the level of cAMP is known to indicate carbon nutrient status and the competency of cells to traverse various restriction points in the cell cycle of other eukaryotes. We wished to determine the profile of cAMP content in free-running, dividing and non-dividing cultures of green, wild-type cells, which survive well during prolonged growth arrest. We monitored cAMP content in photoautothropic cultures of E. gracilis (strain Z) at 25 degrees C under either an entraining light-dark cycle comprising 12 h of light and 12 h of darkness (LD:12,12) or free-running (LD:1/2,1/2) regimes. cAMP content in rhythmically dividing, light-phased or free-running cells exhibited bimodality [peaks at CT (circadian time) 9-14 and CT 19-22). Expression of cAMP content on a per milligram total cellular protein basis caused the day trough (CT 1-3) to be even more distinct. Non-dividing, free-running, photoautotrophic cultures displayed a similarly phased bimodality in cAMP content. These findings in wild-type Euglena confirm that the bimodal rhythm of cAMP content is regulated by the circadian oscillator that underlies division rhythmicity but is not dependent on the cell division cycle. We will now determine the effect of the fluctuating cAMP levels on the phosphorylation status and activity of cell-cycle regulatory proteins.
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Affiliation(s)
- G Mohabir
- Division of Biological Sciences, State University of New York, Stony Brook, 11794-5215, USA
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15
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Bjarnason GA, Jordan RC, Sothern RB. Circadian variation in the expression of cell-cycle proteins in human oral epithelium. THE AMERICAN JOURNAL OF PATHOLOGY 1999; 154:613-22. [PMID: 10027418 PMCID: PMC1849996 DOI: 10.1016/s0002-9440(10)65306-0] [Citation(s) in RCA: 125] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
At the tissue level, there is experimental and clinical data to suggest a cytokinetic coordination of the cell cycle with a greater proportion of cycling cells entering S-phase and mitosis at specific times of the day. The association of certain cell-cycle proteins with defined events in the cell cycle is well established and may be used to study the timing of cell-cycle phases over 24 hours. In this study oral mucosal biopsies were obtained from six normal human volunteers at 4-hour intervals, six times over 24 hours. Using immunohistochemistry, the number of positive cells expressing the proteins p53, cyclin-E, cyclin-A, cyclin-B1, and Ki-67 was determined for each biopsy and expressed as the number of positive cells per mm of basement membrane. We found a statistically significant circadian variation in the nuclear expression of all of these proteins with the high point of expression for p53 at 10:56 hours, cyclin-E at 14:59 hours, cyclin-A at 16:09 hours, cyclin-B1 at 21:13 hours, and Ki-67 at 02:50 hours. The circadian variation in the nuclear expression of cyclins-E (G1/S phase), -A (G2-phase), and -B1 (M-phase) with a normal physiological progression over time suggests a statistically significant circadian variation in oral epithelial cell proliferation. The finding of a circadian variation in the nuclear expression of p53 protein corresponding to late G1 is novel. This information has clinical implications regarding the timing of chemotherapy and radiotherapy.
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Affiliation(s)
- G A Bjarnason
- Toronto-Sunnybrook Regional Cancer Centre, Department of Medicine, University of Toronto, Ontario, Canada.
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16
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Abstract
The time structure of a biological system is at least as intricate as its spatial structure. Whereas we have detailed information about the latter, our understanding of the former is still rudimentary. As techniques for monitoring intracellular processes continuously in single cells become more refined, it becomes increasingly evident that periodic behaviour abounds in all time domains. Circadian timekeeping dominates in natural environments. Here the free-running period is about 24 h. Circadian rhythms in eukaryotes and prokaryotes allow predictive matching of intracellular states with environmental changes during the daily cycles. Unicellular organisms provide excellent systems for the study of these phenomena, which pervade all higher life forms. Intracellular timekeeping is essential. The presence of a temperature-compensated oscillator provides such a timer. The coupled outputs (epigenetic oscillations) of this ultradian clock constitute a special class of ultradian rhythm. These are undamped and endogenously driven by a device which shows biochemical properties characteristic of transcriptional and translational elements. Energy-yielding processes, protein turnover, motility and the timing of the cell-division cycle processes are all controlled by the ultradian clock. Different periods characterize different species, and this indicates a genetic determinant. Periods range from 30 min to 4 h. Mechanisms of clock control are being elucidated; it is becoming evident that many different control circuits can provide these functions.
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Affiliation(s)
- D Lloyd
- Microbiology Group (PABIO), University of Wales Cardiff, UK
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Torres-Márquez ME, Macías-Silva M, Vega-Segura A. Identification of a functional Gs protein in Euglena gracilis. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. PART C, PHARMACOLOGY, TOXICOLOGY & ENDOCRINOLOGY 1996; 115:233-7. [PMID: 9375361 DOI: 10.1016/s0742-8413(96)00105-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We found a Gs protein coupled to adenylyl cyclase in a free-living protist, Euglena gracilis. This Gs protein of approximately 42 kDa is substrate for cholera toxin and is recognized by an antibody against the C-terminal decapeptide of Gs. Furthermore, this protein is coupled to adenylyl cyclase, as shown by: (a) the activation of the enzyme by GTP-analogues and (b) the effect of cholera toxin on cAMP accumulation in intact cells and the continuous activation of adenylyl cyclase activity in membranes. These data indicate that the Gs-adenylyl cyclase-coupled system is already apparent in the protist kingdom.
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Affiliation(s)
- M E Torres-Márquez
- Departamento de Bioquímica, Instituto Nacional de Cardiologia Ignacio Chávez, México, D.F., México
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Edmunds LN. Clocks, cell cycles, cancer, and aging. Role of the adenylate cyclase-cyclic AMP-phosphodiesterase axis in signal transduction between circadian oscillator and cell division cycle. Ann N Y Acad Sci 1994; 719:77-96. [PMID: 8010627 DOI: 10.1111/j.1749-6632.1994.tb56821.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- L N Edmunds
- Division of Biological Sciences, State University of New York at Stony Brook 11794
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