Phosphate metabolism in blue-green algae. I. Fine structure of the "polyphosphate overplus" phenomenon in Plectonema boryanum

1974 ◽  
Vol 20 (9) ◽  
pp. 1235-1239 ◽  
Author(s):  
Thomas E. Jensen ◽  
Linda M. Sicko
Keyword(s):  
Fine Structure ◽  
Development Process ◽  
Phosphate Starvation ◽  
Small Cells ◽  
Phosphate Metabolism ◽  
Electron Microscope Level ◽  
Blue Green Algae ◽  
Cell Architecture ◽  
Polyphosphate Bodies ◽  
Polyhedral Bodies

Changes in cell architecture at the electron microscope level have been followed in P. boryanum during conditions of phosphate starvation and rapid uptake. Cells from 14-day-old cultures were starved of phosphorus for 5 days and then inoculated into a medium containing 10 mg PO4/liter. Polyphosphate bodies developed in five different areas of the cells: (1) in ribosomal areas, (2) on strands of DNA, (3) intrathylakoidally, (4) in polyhedral bodies, and (5) in areas of medium electron density which develop in nucleoplasmic areas. In control cells types 1 and 2 predominate. In phosphate-starved cells types 1, 2, and 5 predominate, and under conditions of rapid uptake types 4 and 5 are predominant. Details of the development process and its significance are discussed. In addition to the described variations in polyphosphate bodies during phosphorus starvation, the number of cyanophycean granules and lipid-like inclusions increase. Cell division is also abnormal in many of the phosphorus-starved cells, with both small cells and abnormally large cells being common. Thylakoid structure is altered under different phosphate concentrations. Expanded thylakoids are found in control algae; the frequency increases during starvation with the greatest number occurring during a rapid uptake. Other aspects of cell architecture are discussed in relation to the "overplus phenomenon."

Ultrastructure of primary spermatocyte in fish (Tilapia: Oreochromis niloticus): The synaptonemal complex

1986 ◽  
Vol 44 ◽  
pp. 288-289
Author(s):  
T. Guha ◽  
A. Q. Siddiqui ◽  
P. F. Prentis
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Synaptonemal Complex ◽  
Oreochromis Niloticus ◽  
Short Communication ◽  
Primary Spermatocyte ◽  
Mitotic Division ◽  
Meiotic Cell ◽  
Electron Microscope Level ◽  
Homologous Chromosomes

The Primary Spermatocytes represent a stage in spermatogenesis when the first meiotic cell division occurs. They are derived from Spermatogonium or Stem cell through mitotic division. At the zygotene phase of meiotic prophase the Synaptonemal complex appears in these cells in the space between the paired homologous chromosomes. Spermatogenesis and sperm structure in fish have been studied at the electron microscope level in a few species? However, no work has yet been reported on ultrastructure of tilapia, O. niloticus, spermatozoa and spermatogenetic process. In this short communication we are reporting the Ultrastructure of Primary Spermatocytes in tilapia, O. niloticus, and the fine structure of synaptonemal complexes seen in the spermatocyte nuclei.

A comparison of the fine structure and nucleic acid biochemistry of chloroplasts and blue-green algae

PROTOPLASMA ◽  
1971 ◽  
Vol 72 (2-3) ◽  
pp. 325-357 ◽  
Author(s):  
B. A. Whitton ◽  
N. G. Carr ◽  
I. W. Craig
Keyword(s):  
Fine Structure ◽  
Nucleic Acid ◽  
Green Algae ◽  
Blue Green Algae

scholarly journals Sugar-phosphate metabolism regulates stationary phase entry and stalk elongation in Caulobacter crescentus

2019 ◽  
Author(s):  
Kevin D. de Young ◽  
Gabriele Stankeviciute ◽  
Eric A. Klein
Keyword(s):  
Stationary Phase ◽  
Caulobacter Crescentus ◽  
Phosphate Uptake ◽  
Phosphate Starvation ◽  
Phosphate Metabolism ◽  
Phosphomannose Isomerase ◽  
Sugar Phosphate ◽  
Environmental Perturbations ◽  
Stalk Length ◽  
Phase Entry

AbstractBacteria have a variety of mechanisms for adapting to environmental perturbations. Changes in oxygen availability result in a switch between aerobic and anaerobic respiration, whereas iron limitation may lead to siderophore secretion. In addition to metabolic adaptations, many organisms respond by altering their cell shape. Caulobacter crescentus, when grown under phosphate limiting conditions, dramatically elongates its polar stalk appendage. The stalk is hypothesized to facilitate phosphate uptake; however, the mechanistic details of stalk synthesis are not well characterized. We used a chemical mutagenesis approach to isolate and characterize stalk-deficient mutants, one of which had two mutations in the phosphomannose isomerase gene (manA) that were necessary and sufficient to inhibit stalk elongation. Transcription of the pho regulon was unaffected in the manA mutant; therefore, ManA plays a unique regulatory role in stalk synthesis. The mutant ManA had reduced enzymatic activity resulting in a 5-fold increase in the intracellular fructose 6-phosphate: mannose 6-phosphate ratio. This metabolic imbalance impaired the synthesis of cellular envelope components derived from mannose 6-phosphate, namely lipopolysaccharide O-antigen and exopolysaccharide. Furthermore, the manA mutations prevented C. crescentus cells from efficiently entering stationary phase. Deletion of the stationary-phase response regulator spdR inhibited stalk elongation in wild-type cells while overproduction of the alarmone ppGpp, which triggers growth arrest and stationary phase entry, increased stalk length in the manA mutant strain. These results demonstrate that sugar-phosphate metabolism regulates stalk elongation independently of phosphate starvation.ImportanceBacteria have various mechanisms for adapting to environmental perturbations including morphological alterations. During phosphate limitation, Caulobacter crescentus dramatically elongates its polar stalk appendage. The stalk is hypothesized to facilitate phosphate uptake; however, the mechanism of stalk synthesis is not well characterized. We isolated stalk-deficient mutants, one of which had mutations in the phosphomannose isomerase gene (manA) that blocked stalk elongation, despite normal activation of the phosphate-starvation response. The mutant ManA produced an imbalance in sugar-phosphate concentrations that impaired the synthesis of cellular envelope components and prevented entry into stationary phase. Overproduction of the alarmone ppGpp, which promotes stationary phase entry, increased stalk length in the manA mutant demonstrating that sugar-phosphate metabolism regulates stalk elongation independently of phosphate starvation.

Structural Organization of Detergent-Extracted Cells

1980 ◽  
Vol 38 ◽  
pp. 814-817
Author(s):  
Manfred Schliwa
Keyword(s):  
Electron Microscopy ◽  
Fine Structure ◽  
Conformational Changes ◽  
Structural Organization ◽  
Three Dimensional ◽  
High Voltage Electron Microscopy ◽  
Dimensional Lattice ◽  
Voltage Electron ◽  
Cell Architecture ◽  
Critical Point Drying

Adequate visualization of the three-dimensional organization has always been a major problem in studies of cell architecture. Efforts of numerous investigators weredevoted to the question of how best information can be collected from specimens prepared with different procedures. In recent years, the potential of high voltage electron microscopy has been combined with a technique for sample preparation that circumvents embedding, namely critical point-drying from CO2, to study the three-dimensional fine structure of cells in culture. This approach has revealed new insights into the structural organization of the cytoplasm (1-4). A system of slender strands or microtrabeculae has been described to form an elaborate three-dimensional lattice in which other organelles are embedded. This system has been shown in some cells to undergo rapid conformational changes (3,5) and in general is believed to be an important component of the cytoskeleton, being responsible for the gelatious properties of the cytoplasm.

The organization of the auditory organ of the bladder cicada, Cystosoma saundersii

1981 ◽  
Vol 291 (1055) ◽  
pp. 525-540 ◽  
Keyword(s):  
Fine Structure ◽  
Auditory Nerve ◽  
Longitudinal Axis ◽  
Sensory Transduction ◽  
Chordotonal Organ ◽  
Electron Microscope Level ◽  
Central Projections ◽  
Periodical Cicadas ◽  
Adequate Stimulus ◽  
Auditory Organ

The auditory organ of Cystosoma saundersii consists of 2000-2200 scolopidia arranged in two groups, a dorsal and a ventral group. The dorsal group contains scolopidia orientated along the longitudinal axis of the organ while the ventral group contains scolopidia aligned at right angles to these. On the basis of current theories of sensory transduction, it is possible that these groups may have different intensity characteristics. The cellular composition of an individual scolopidium was described at the electron microscope level and was found to be similar to that occurring in most other chordotonal organs. Slight differences in fine structure were observed in the structure of the scolopale, the mass and position of the ciliary dilatation and the ciliary root. Differences in these parameters may influence the adequate stimulus needed for a chordotonal organ. The fine structure of proximal and distal attachments of the scolopidia to the cuticle is similar to that of muscle attachments observed in insects, crustaceans and arachnids. The central projections of the auditory nerve within the thoracic ganglia are similar to those described for the periodical cicadas.

Blue-Green Algae: Fine Structure of the Gas Vacuoles

Science ◽  
1965 ◽  
Vol 147 (3664) ◽  
pp. 1460-1462 ◽  
Author(s):  
C. C. Bowen ◽  
T. E. Jensen
Keyword(s):  
Fine Structure ◽  
Green Algae ◽  
Blue Green Algae ◽  
Gas Vacuoles

scholarly journals Phosphate Metabolism in Blue-green Algae

CYTOLOGIA ◽  
1977 ◽  
Vol 42 (2) ◽  
pp. 357-369 ◽  
Author(s):  
Thomas E. Jensen ◽  
Linda Sicko-Goad ◽  
Robert P. Ayala
Keyword(s):  
Green Algae ◽  
Phosphate Metabolism ◽  
Blue Green Algae

Structural Variations of Polyphosphate Bodies in Blue-Green Algae

1972 ◽  
Vol 30 ◽  
pp. 218-219
Author(s):  
Linda M. Sicko
Keyword(s):  
Green Algae ◽  
Culture Media ◽  
Electron Microscopic Examination ◽  
Culture Conditions ◽  
Structural Variations ◽  
Electron Microscopic ◽  
Blue Green Algae ◽  
Stage Of Development ◽  
Wide Range ◽  
Polyphosphate Bodies

Polyphosphate appears to be a ubiquitous component of all microorganisms. Electron microscopic examination of blue-green algae reveals bodies which are usually spherical, and have a wide range of electron densities. From work conducted in our laboratory, it appears that the image of the polyphosphate bodies varies with the culture conditions as well as the stage of development under constant culture conditions. The following report describes the various images one can observe.For most experiments, the blue-green algae were fixed by the method of Pankratz and Bowen. The algae were pelleted, the culture media poured off, and the pellet was resuspended in 1% OsO4 buffered at pH 6.2 for 3 hours at room temperature.

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