scholarly journals INORGANIC CATIONS IN THE CELL NUCLEUS

1972 ◽  
Vol 53 (2) ◽  
pp. 483-493 ◽  
Author(s):  
Laura L. Tres ◽  
A. L. Kierszenbaum ◽  
C. J. Tandler
Keyword(s):  
Meiotic Prophase ◽  
Rna Synthesis ◽  
Adult Mouse ◽  
Divalent Cations ◽  
Synthetic Activity ◽  
Inorganic Cations ◽  
Transcription Process ◽  
Inorganic Cation ◽  
Interchromatin Granules ◽  
Potassium Pyroantimonate

Earlier reports indicated the presence of significant amounts of inorganic salts in the nucleus. In the present study the possibility that this might be related to the transcription process was tested on seminiferous epithelium of the adult mouse, using potassium pyroantimonate as a fixative. The results indicated that a correlation exists between the inorganic cations comprising the pyroantimonate-precipitable fraction and the RNA synthetic activity. During meiotic prophase an accumulation of cation-antimonate precipitates occurs dispersed through the middle pachytene nuclei, the stage in which RNA synthesis reaches a maximum. At other stages (zygotene to diplotene), where RNA synthesis falls to a low level, that pattern is not seen; cation-antimonate deposits are restricted to a few masses in areas apparently free of chromatin. The condensed sex chromosomes, the heterochromatin of the "basal knobs," the axial elements, and the synaptonemal complexes are devoid of antimonate deposits during the meiotic prophase. The Sertoli cells, active in RNA synthesis in both nucleoplasm and nucleolus, show cation-antimonate deposits at these sites. In the nucleoplasm some "patches" of precipitates appear coincident with clusters of interchromatin granules; in the nucleolus the inorganic cations are mainly located in the fibrillar and/or amorphous areas, whereas relatively few are shown by the granular component. The condensed chromatin bodies associated with the nucleolus were always free of antimonate precipitates. It is suggested that the observed sites of inorganic cation accumulation within the nucleus may at least partially indicate the presence of RNA polymerases, the activity of which is dependent on divalent cations.

scholarly journals THE INTRACELLULAR LOCALIZATION OF INORGANIC CATIONS WITH POTASSIUM PYROANTIMONATE

1970 ◽  
Vol 45 (2) ◽  
pp. 355-366 ◽  
Author(s):  
Carlos J. Tandler ◽  
César M. Libanati ◽  
Carlos A. Sanchis
Keyword(s):  
Cell Morphology ◽  
Intact Cell ◽  
Intracellular Localization ◽  
Bound State ◽  
Plant Tissues ◽  
Inorganic Cations ◽  
Large Pool ◽  
Inorganic Cation ◽  
Calcium Magnesium ◽  
Potassium Pyroantimonate

Potassium pyroantimonate, when used as fixative (saturated or half-saturated, without addition of any conventional fixative) has been demonstrated to produce intracellular precipitates of the insoluble salts of calcium, magnesium, and sodium and to preserve the general cell morphology. In both animal and plant tissues, the electron-opaque antimonate precipitates were found deposited in the nucleus—as well as within the nucleolus—and in the cytoplasm, largely at the site of the ribonucleoprotein particles; the condensed chromatin appeared relatively free of precipitates. The inorganic cations are probably in a loosely bound state since they are not retained by conventional fixatives. The implications of this inorganic cation distribution in the intact cell are discussed in connection with their anionic counterparts, i.e., complexing of cations by fixed anionic charges and the coexistence of a large pool of inorganic orthophosphate anions in the nucleus and nucleolus.

scholarly journals NUCLEOLAR AND PERICHROMOSOMAL RNA SYNTHESIS DURING MEIOTIC PROPHASE IN THE MOUSE TESTIS

1974 ◽  
Vol 60 (1) ◽  
pp. 39-53 ◽  
Author(s):  
A. L. Kierszenbaum ◽  
Laura L. Tres
Keyword(s):  
Sex Chromosomes ◽  
Meiotic Prophase ◽  
Rna Synthesis ◽  
Transcriptional Activity ◽  
Mouse Testis ◽  
Synthetic Activity ◽  
Synthetic Cell ◽  
Nucleolar Organizers ◽  
Nucleolar Rna ◽  
Silver Grains

The transcriptional activity during meiotic prophase in the mouse testis is studied with light microscopy and high-resolution autoradiographic techniques using [3H]uridine as a labeled precursor. In the present study, two types of RNA synthesis are detected during meiotic prophase: an extranucleolar RNA synthesis of perichromosomal localization and a nucleolar RNA synthetic activity. In some of the autosomes and close to the basal knobs, the activity of the nucleolar organizers is evidenced by the incorporation of [3H]uridine into nucleolar masses from zygotene on and at earlier labeling times. The evolution of nucleoli and the formation of a nucleolus attached to the sex pair are described during the different meiotic stages. Perichromosomal labeling, from leptotene on, reaches a maximum during middle pachytene and falls progressively to a low level at longer incorporation times. Sertoli's cell, the most active RNA synthetic cell in the seminiferous epithelium, rises to a maximum of labeling and drops at earlier times compared with the meiotic prophase cells. The condensed sex chromosomes show some scattered silver grains especially at middle pachytene. The axial chromosome cores and synaptonemal complexes are devoid of silver grains during the meiotic prophase. The observations suggest that a control mechanism operates during meiotic prophase to regulate transcriptional activity in the sex chromosomes and to provide differential RNA synthesis in autosomal bivalents at various stages of prophase and within certain segments of the chromosomes.

scholarly journals THE DISTRIBUTION OF INORGANIC CATIONS IN MOUSE TESTIS

1971 ◽  
Vol 48 (2) ◽  
pp. 314-323 ◽  
Author(s):  
Abraham L. Kierszenbaum ◽  
Cesar M. Libanati ◽  
Carlos J. Tandler
Keyword(s):  
Aqueous Solution ◽  
Connective Tissue ◽  
Cell Morphology ◽  
Seminiferous Tubules ◽  
Plant Tissues ◽  
Cell Nuclei ◽  
Double Line ◽  
Inorganic Cations ◽  
Inorganic Cation ◽  
Potassium Pyroantimonate

For localization of pyroantimonate-precipitable cations, mouse testes were fixed with a saturated aqueous solution of potassium pyroantimonate (pH about 9.2, without addition of any conventional fixative), hardened with formaldehyde, and postosmicated. A good preservation of the cell membranes and over-all cell morphology is obtained as well as a consistent and reproducible localization of the insoluble antimonate salts of magnesium, calcium, and sodium. Four sites of prominent antimonate deposits are revealed, besides a more or less uniform distribution of the precipitates. These sites are: (a) In the walls of the seminiferous tubules, localized in two concentric layers corresponding to the inner and outer layers of the tubular wall; (b) Around the blood vessels and adjacent connective tissue; (c) At the area of contact between the Sertoli cell and spermatids, where a double line of precipitate surrounds the head of the mature spermatids; and (d) In the cell nuclei, disposed between regions of the condensed chromatin. The nucleus of mature spermatids did not show any sign of antimonate precipitation. The implications of this inorganic cation distribution are discussed with relation to their anionic counterparts, their localization in other animal and plant tissues, and the possibility that those sites may represent barriers to the free passage of ions.

scholarly journals Avian reovirus core protein μA expressed in Escherichia coli possesses both NTPase and RTPase activities

2007 ◽  
Vol 88 (6) ◽  
pp. 1797-1805 ◽  
Author(s):  
Yu Pin Su ◽  
Jui Huang Shien ◽  
Hung Jen Liu ◽  
Hsien Sheng Yin ◽  
Long Huw Lee
Keyword(s):  
Active Site ◽  
Rna Synthesis ◽  
Core Protein ◽  
Divalent Cations ◽  
Fusion Peptide ◽  
Enzymic Activity ◽  
Avian Reovirus ◽  
Phosphate Release ◽  
N Terminus ◽  
Rna Triphosphatase

Analysis of the amino acid sequence of core protein μA of avian reovirus has indicated that it may share similar functions to protein μ2 of mammalian reovirus. Since μ2 displayed both nucleotide triphosphatase (NTPase) and RNA triphosphatase (RTPase) activities, the purified recombinant μA ( μA) was designed and used to test these activities. μA was thus expressed in bacteria with a 4.5 kDa fusion peptide and six His tags at its N terminus. Results indicated that  μA possessed NTPase activity that enabled the protein to hydrolyse the β–γ phosphoanhydride bond of all four NTPs, since NDPs were the only radiolabelled products observed. The substrate preference was ATP>CTP>GTP>UTP, based on the estimated k cat values. Alanine substitutions for lysines 408 and 412 (K408A/K412A) in a putative nucleotide-binding site of  μA abolished NTPase activity, further suggesting that NTPase activity is attributable to protein  μA. The activity of  μA is dependent on the divalent cations Mg2+ or Mn2+, but not Ca2+ or Zn2+. Optimal NTPase activity of  μA was achieved between pH 5.5 and 6.0. In addition,  μA enzymic activity increased with temperature up to 40 °C and was almost totally inhibited at temperatures higher than 55 °C. Tests of phosphate release from RNA substrates with  μA or K408A/K412A  μA indicated that  μA, but not K408A/K412A  μA, displayed RTPase activity. The results suggested that both NTPase and RTPase activities of  μA might be carried out at the same active site, and that protein μA could play important roles during viral RNA synthesis.

High-resolution autoradiographic localization of DNA-containing sites and RNA synthesis in developing nucleoli of human preimplantation embryos: a new concept of embryonic nucleologenesis

Development ◽  
1987 ◽  
Vol 101 (4) ◽  
pp. 777-791 ◽  
Author(s):  
J. Tesarik ◽  
V. Kopecny ◽  
M. Plachot ◽  
J. Mandelbaum
Keyword(s):  
Rna Synthesis ◽  
Preimplantation Embryos ◽  
Synthetic Activity ◽  
Rrna Synthesis ◽  
Nucleolar Organizer Regions ◽  
Careful Study ◽  
Matrix Elements ◽  
Electron Microscopic Autoradiography ◽  
General Validity ◽  
Granular Component

Human embryos from the 2-cell to the morula stage, obtained by in vitro fertilization, were incubated with [3H]thymidine or [3H]uridine so as to achieve labelling of all replicating nuclear DNA and the newly synthesized RNA, respectively. The label was localized in different structural components of developing nucleoli using electron microscopic autoradiography. Careful study of the relationship between the structural pattern and nucleic acid distribution made it possible to define four stages of embryonic nucleologenesis. Homogeneous nuclear precursors (i) consist of nucleolar matrix elements appearing as filaments of 3 nm thickness, (ii) do not contain recently replicated DNA and (iii) lack RNA synthetic activity. Penetration of DNA into these bodies is a key event leading to their transformation into heterogeneous nucleolar precursors. In addition to the 3 nm matrix filaments, two types of 5 nm fibrillar components can be recognized in them. The denser type contains DNA and is the site of nucleolar RNA synthesis, while the more loosely arranged 5 nm fibrils are not labelled with [3H]thymidine and apparently represent the newly produced pre-rRNA detached from the transcribing rDNA filament. Compact fibrillogranular nucleoli are characterized by the first appearance of the granular component and reduction of the nontranscribing part of the fibrillar component, both indicating the activation of the machinery for rRNA processing. Finally, the granular component is most evident in reticulated nucleoli, occupying mostly the inner parts of their nucleolonema, while the transcription sites tend to be located at the nucleolar periphery. Our findings advocate a unique concept of embryonic nucleologenesis, different from any other nucleolar event during the cell cycle of differentiated cells. This developmental pattern is characterized by a gradual activation of rRNA synthesis and processing, mediated by progressive association of rDNA and, later on, the newly formed pre-rRNA with pre-existing nucleolar matrix elements that are originally topically separated from nucleolar organizer regions. This model may have a general validity in early animal embryos despite some interspecies variability in the timing of individual steps and resulting structural peculiarities.

scholarly journals The essential activities of the bacterial sigma factor

2017 ◽  
Vol 63 (2) ◽  
pp. 89-99 ◽  
Author(s):  
Maria C. Davis ◽  
Christopher A. Kesthely ◽  
Emily A. Franklin ◽  
Shawn R. MacLellan
Keyword(s):  
Gene Expression ◽  
Transcription Factors ◽  
Rna Synthesis ◽  
Gene Expression Regulation ◽  
Structure And Function ◽  
Structural Studies ◽  
General Transcription Factors ◽  
Transcription Process ◽  
Promoter Dna ◽  
And Function

Transcription is the first and most heavily regulated step in gene expression. Sigma (σ) factors are general transcription factors that reversibly bind RNA polymerase (RNAP) and mediate transcription of all genes in bacteria. σ Factors play 3 major roles in the RNA synthesis initiation process: they (i) target RNAP holoenzyme to specific promoters, (ii) melt a region of double-stranded promoter DNA and stabilize it as a single-stranded open complex, and (iii) interact with other DNA-binding transcription factors to contribute complexity to gene expression regulation schemes. Recent structural studies have demonstrated that when σ factors bind promoter DNA, they capture 1 or more nucleotides that are flipped out of the helical DNA stack and this stabilizes the promoter open-complex intermediate that is required for the initiation of RNA synthesis. This review describes the structure and function of the σ70 family of σ proteins and the essential roles they play in the transcription process.

A Lepidopteran Saline: Effects of Inorganic Cation Concentrations on Sensory, Reflex and Motor Responses in a Herbivorous Insect

1966 ◽  
Vol 44 (1) ◽  
pp. 163-175 ◽  
Author(s):  
R. DE G. WEEVERS
Keyword(s):  
Divalent Cations ◽  
Herbivorous Insect ◽  
Muscle Action ◽  
Photometric Analysis ◽  
Action Current ◽  
Inorganic Cation ◽  
Muscle Action Potential ◽  
Muscle Receptors ◽  
Synthetic Media

1. The inorganic cations in the haemolymph of Antheræa pernyi larvae and pupae were analysed by flame photometry. 2. Synthetic media based on these analyses were compared with haemolymph in their effects on the muscle action potential and on the response of the dorsal muscle receptors to a standard stretch. 3. The best match with haemolymph was obtained in all cases with concentrations of divalent cations considerably below the values found by flame photometric analysis. Binding to haemolymph proteins is probably not the major factor responsible for lowering the ionic activities of calcium and magnesium. 4. The role of magnesium in neuromuscular transmission is discussed. It is concluded that in phytophagous Lepidoptera this ion may carry a proportion of the muscle action current.

scholarly journals INORGANIC CATIONS IN RAT KIDNEY

1971 ◽  
Vol 50 (3) ◽  
pp. 830-839 ◽  
Author(s):  
C. J. Tandler ◽  
A. L. Kierszenbaum
Keyword(s):  
Aqueous Solution ◽  
Connective Tissue ◽  
Rat Kidney ◽  
Basement Membranes ◽  
Cell Nuclei ◽  
Inorganic Cations ◽  
Dense Granules ◽  
Distal Tubules ◽  
The Masses ◽  
Potassium Pyroantimonate

For localization of pyroantimonate-precipitable cations, rat kidney was fixed by perfusion with a saturated aqueous solution of potassium pyroantimonate (pH about 9.2, without addition of any conventional fixative). A remarkably good preservation of the tissue and cell morphology was obtained as well as a consistent and reproducible localization of the insoluble antimonate salts of magnesium, calcium, and sodium. All proximal and distal tubules and glomeruli were delimited by massive electron-opaque precipitates localized in the basement membrane and, to a lesser extent, in adjacent connective tissue. In the intraglomerular capillaries the antimonate precipitate was encountered in the basement membranes and also between the foot processes. In addition to a more or less uniform distribution in the cytoplasm and between the microvilli of the brush border, antimonate precipitates were found in all cell nuclei, mainly between the masses of condensed chromatin. The mitochondria usually contained a few large antimonate deposits which probably correspond to the so-called "dense granules" observed after conventional fixations.

scholarly journals Effect of non-histone chromosomal proteins on transcription in vitro in sea-urchin

1978 ◽  
Vol 174 (1) ◽  
pp. 95-102 ◽  
Author(s):  
E Di Mauro ◽  
F Pedone ◽  
M Pomponi
Keyword(s):  
Sea Urchin ◽  
Rna Synthesis ◽  
Paracentrotus Lividus ◽  
Chromosomal Proteins ◽  
Stage Of Development ◽  
Transcription Process ◽  
Initiation Step ◽  
Transcription In Vitro ◽  
Transcription 3

Non-histone chromosomal proteins prepared from chromosomal material of the sea-urchin Paracentrotus lividus affect RNA synthesis in vitro. 1. The extent of transcription can be radically changed from inhibition to stimulation, depending on the DNA/non-histone chromosomal proteins ratio. 2. A correlation exists between stage of development and influence on transcription. 3. Non-histone chromosomal proteins exert their action by intervening directly on some initiation step of RNA synthesis, as shown by the numbers of initiation events that take place in their presence or absence. 4. Stimulatory activity is observed only in restrictive conditions of ionic strength and temperature. These observations are in agreement with models that predict for non-histone chromosomal proteins a regulatory role on the transcription process exerted through a modulation of promoter availability.

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