Irreversible Plastid Loss in Euglena gracilis under Physiological Conditions

Giant mitochondria of various shapes and with different internal structures and matrix density have been observed in a great number of tissues including nerves. In most instances, the presence of giant mitochondria has been associated with a known disease or with abnormal physiological conditions such as anoxia or exposure to cytotoxic compounds. In these cases degenerative changes occurred in other cell organelles and, therefore the giant mitochondria also were believed to be induced structural abnormalities.Schwann cells ensheating unmyelinated axons of bovine splenic nerve regularly contain giant mitochondria in addition to the conventional smaller type (Fig. 1). These nerves come from healthy inspected animals presumed not to have been exposed to noxious agents. As there are no drastic changes in the small mitochondria and because other cell components also appear reasonably well preserved, it is believed that the giant mitochondria are normally present jin vivo and have not formed as a post-mortem artifact.

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Organization of the Pellicle and the Muciferous Glands in Euglena Gracilis

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100067510 ◽

1970 ◽

Vol 28 ◽

pp. 104-105

Author(s):

Hilton H. Mollenhauer ◽

W. Evans

Keyword(s):

Plasma Membrane ◽

Euglena Gracilis ◽

Complex Forms ◽

Secondary Periodicity

The pellicular structure of Euglena gracilis consists of a series of relatively rigid strips (Fig. 1) composed of ridges and grooves which are helically oriented along the cell and which fuse together into a common junction at either end of the cell. The strips are predominantly protein and consist in part of a series of fibers about 50 Å in diameter spaced about 85 Å apart and with a secondary periodicity of about 450 Å. Microtubules are also present below each strip (Fig. 1) and are often considered as part of the pellicular complex. In addition, there may be another fibrous component near the base of the pellicle which has not yet been very well defined.The pellicular complex lies underneath the plasma membrane and entirely within the cell (Fig. 1). Each strip of the complex forms an overlapping junction with the adjacent strip along one side of each groove (Fig. 1), in such a way that a certain amount of sideways movement is possible between one strip and the next.

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Immunocytochemical studies on the behavior of RuBisCO and LHCP II during the cell cycle of synchronized Euglena gracilis

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100160868 ◽

1990 ◽

Vol 48 (3) ◽

pp. 662-663

Author(s):

Tetsuaki Osafune ◽

Shuji Sumida ◽

Tomoko Ehara ◽

Eiji Hase ◽

Jerome A. Schiff

Keyword(s):

Cell Cycle ◽

Immunoelectron Microscopy ◽

Growth Phase ◽

Euglena Gracilis ◽

Dark Period ◽

Light Period ◽

Carboxylase Activity ◽

Immunocytochemical Studies ◽

Lhcp Ii

Changes in the morphology of pyrenoid and the distribution of RuBisCO in the chloroplast of Euglena gracilis were followed by immunoelectron microscopy during the cell cycle in a light (14 h)- dark (10 h) synchronized culture under photoautotrophic conditions. The imrnunoreactive proteins wereconcentrated in the pyrenoid, and less densely distributed in the stroma during the light period (growth phase, Fig. 1-2), but the pyrenoid disappeared during the dark period (division phase), and RuBisCO was dispersed throughout the stroma. Toward the end of the division phase, the pyrenoid began to form in the center of the stroma, and RuBisCO is again concentrated in that pyrenoid region. From a comparison of photosynthetic CO2-fixation with the total carboxylase activity of RuBisCO extracted from Euglena cells in the growth phase, it is suggested that the carboxylase in the pyrenoid functions in CO2-fixation in photosynthesis.

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Freeze-fracture observations on changes in the distribution of Filipin-sterol complexes during epididymal maturation and capacitation of boar spermatozoa

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100157991 ◽

1990 ◽

Vol 48 (3) ◽

pp. 90-91

Author(s):

N. Seki ◽

Y. Toyama ◽

T. Nagano

Keyword(s):

Plasma Membrane ◽

Essential Role ◽

Freeze Fracture ◽

Final Concentration ◽

Freeze Fracturing ◽

Physiological Conditions ◽

Epididymal Maturation ◽

Cacodylate Buffer ◽

Sperm Membrane ◽

Boar Spermatozoa

It is believed that i ntramembra.nous sterols play an essential role in membrane stability and permeability. To investigate the distribution changes of sterols in sperm membrane during epididymal maturation and capacitation, filipin has been used as a cytochemical probe for the detection for membrane sterols. Using this technique in combination with freeze fracturing, we examined the boar spermatozoa under various physiological conditions.The spermatozoa were collected from: 1) caput, corpus and cauda epididymides, 2) sperm rich fraction of ejaculates, and 3)the uterus 2hr after natural coition. They were fixed with 2.5% glutaraldehyde in 0.05M cacodylate buffer (pH 7.4), and treated with the filipin solution (final concentration : 0.02.0.05%) for 24hr at 4°C with constant agitation. After the filipin treatment, replicas were made by conventional freeze-fracture technique. The density of filipin-sterol complexes (FSCs) was determined in the E face of the plasma membrane of head regions.

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Three-dimensional distribution of ribulose-1, 5-bisphosphate carboxylase/oxygemase during the early development of proplastids in dark-grown Euglena cells transferred to an inorganic medium

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100162090 ◽

1990 ◽

Vol 48 (3) ◽

pp. 906-907

Author(s):

Tomoko Ehara ◽

Shuji Sumida ◽

Tetsuaki Osafune ◽

Eiji Hase

Keyword(s):

Cell Suspension ◽

Euglena Gracilis ◽

Carbon Materials ◽

Three Dimensional ◽

Peripheral Region ◽

Plastid Development ◽

Bisphosphate Carboxylase ◽

Inorganic Medium ◽

Ribulose 1 ◽

Dimensional Distribution

As shown previously, Euglena cells grown in Hutner’s medium in the dark without agitation accumulate wax as well as paramylum, and contain proplastids showing no internal structure except for a single prothylakoid existing close to the envelope. When the cells are transferred to an inorganic medium containing ammonium salt and the cell suspension is aerated in the dark, the wax was oxidatively metabolized, providing carbon materials and energy 23 for some dark processes of plastid development. Under these conditions, pyrenoid-like structures (called “pro-pyrenoids”) are formed at the sites adjacent to the prolamel larbodies (PLB) localized in the peripheral region of the proplastid. The single prothylakoid becomes paired with a newly formed prothylakoid, and a part of the paired prothylakoids is extended, with foldings, in to the “propyrenoid”. In this study, we observed a concentration of RuBisCO in the “propyrenoid” of Euglena gracilis strain Z using immunoelectron microscopy.

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Impact of graft size and commissural resuspension height on aortic valve competence in valve-sparing aortic root replacement under physiological conditions

The Thoracic and Cardiovascular Surgeon ◽

10.1055/s-0029-1191612 ◽

2009 ◽

Vol 56 (S 01) ◽

Author(s):

J Babin-Ebell ◽

HH Sievers ◽

H Freiherr Grote ◽

M Scharfschwerdt

Keyword(s):

Aortic Valve ◽

Aortic Root ◽

Aortic Root Replacement ◽

Graft Size ◽

Physiological Conditions ◽

Valve Sparing

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Influence of stable iodine on the uptake of the thyroid – model vs. experiment

Nuklearmedizin ◽

10.1055/s-0038-1623989 ◽

2001 ◽

Vol 40 (01) ◽

pp. 31-37 ◽

Cited By ~ 1

Author(s):

U. Wellner ◽

E. Voth ◽

H. Schicha ◽

K. Weber

Keyword(s):

Time Course ◽

Compartment Model ◽

The Body ◽

Iodine Uptake ◽

Model Calculations ◽

Physiological Conditions ◽

Iodine Supply ◽

Predicted Values ◽

The Individual ◽

Stable Iodine

Summary Aim: The influence of physiological and pharmacological amounts of iodine on the uptake of radioiodine in the thyroid was examined in a 4-compartment model. This model allows equations to be derived describing the distribution of tracer iodine as a function of time. The aim of the study was to compare the predictions of the model with experimental data. Methods: Five euthyroid persons received stable iodine (200 μg, 10 mg). 1-123-uptake into the thyroid was measured with the Nal (Tl)-detector of a body counter under physiological conditions and after application of each dose of additional iodine. Actual measurements and predicted values were compared, taking into account the individual iodine supply as estimated from the thyroid uptake under physiological conditions and data from the literature. Results: Thyroid iodine uptake decreased from 80% under physiological conditions to 50% in individuals with very low iodine supply (15 μg/d) (n = 2). The uptake calculated from the model was 36%. Iodine uptake into the thyroid did not decrease in individuals with typical iodine supply, i.e. for Cologne 65-85 μg/d (n = 3). After application of 10 mg of stable iodine, uptake into the thyroid decreased in all individuals to about 5%, in accordance with the model calculations. Conclusion: Comparison of theoretical predictions with the measured values demonstrated that the model tested is well suited for describing the time course of iodine distribution and uptake within the body. It can now be used to study aspects of iodine metabolism relevant to the pharmacological administration of iodine which cannot be investigated experimentally in humans for ethical and technical reasons.

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Interaction of Plasminogen Activators and Plasminogen with Heparin: Effect of Ionic Strength

Thrombosis and Haemostasis ◽

10.1055/s-0038-1649685 ◽

1993 ◽

Vol 70 (05) ◽

pp. 867-872 ◽

Cited By ~ 21

Author(s):

Dingeman C Rijken ◽

Gerard A W de Munk ◽

Annie F H Jie

Keyword(s):

Molecular Weight ◽

Ionic Strength ◽

Plasminogen Activator ◽

Plasminogen Activators ◽

Fibrinolytic System ◽

Tissue Type ◽

Single Chain ◽

Physiological Conditions ◽

Amino Terminal ◽

Type Plasminogen Activator

SummaryIn order to define the possible effects of heparin on the fibrinolytic system under physiological conditions, we studied the interactions of this drug with plasminogen and its activators at various ionic strengths. As reported in recent literature, heparin stimulated the activation of Lys-plasminogen by high molecular weight (HMW) and low molecular weight (LMW) two-chain urokinase-type plasminogen activator (u-PA) and two-chain tissue-type plasminogen activator (t-PA) 10- to 17-fold. Our results showed, however, that this stimulation only occurred at low ionic strength and was negligible at a physiological salt concentration. Direct binding studies were performed using heparin-agarose column chromatography. The interaction between heparin and Lys-plasminogen appeared to be salt sensitive, which explains at least in part why heparin did not stimulate plasminogen activation at 0.15 M NaCl. The binding of u-PA and t-PA to heparinagarose was less salt sensitive. Results were consistent with heparin binding sites on both LMW u-PA and the amino-terminal part of HMW u-PA. Single-chain t-PA bound more avidly than two-chain t-PA. The interactions between heparin and plasminogen activators can occur under physiological conditions and may modulate the fibrinolytic system.

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