Isolation and certain features of a polyphosphate phosphohydrolase deficient mutant of the fungus Neurospora crassa

A polyphosphatase deficient mutant of Neurospora crassa has been isolated. The criterion for selecting the mutant was the capacity of the fungus to assimilate polyphosphates as the source of exogenous phosphorus. The mutant like the parent strain ad-6, was an adenine auxotroph but differed from the parent strain by a lower growth rate though, at the stationary stage, its biomass reached the same level as in the strain ad-6. The character of changes in the activity of polyphosphatase in the course of growth was the same in the two cultures, but the activity of the enzyme in the mutant was considerably lower at all the growth stages. The content of polyphosphate fractions with the highest molecular weight increased twofold in the mutant culture. These data suggest that there is a close metabolic and topographic correlation between polyphosphatase and the highest molecular weight fractions of polyphosphates in N. crassa.     

The development of A. N. Belozersky's ideas in polyphosphate biochemistry

This review covers some trends and approaches to the study of inorganic polyphosphates that originated from the fruitful ideas and pioneering works of A. N. Belozersky. This is, first of all, the elucidation of a close relationship between these biopolymers and nucleic acids in organisms at different evolutionary stages; second, the study of "fossil" reactions in polyphosphate metabolism that permit an understanding of their role in the evolution of phosphorus turnover and cell bioenergetics; third, the possible use of the conservative enzymes of polyphosphate metabolism, e.g., exopolyphosphatases, as molecular chronometers for obtaining additional data concerning the theory of the endosymbiotic origin of eukaryotic cells from prokaryotes.     

The concentration dynamics of inorganic polyphosphates during the cephalosporin C synthesis by Acremonium chrysogenum

The contents of five fractions of energy-rich inorganic polyphosphates (polyPs), ATP, and H⁺-ATPase activity in the plasma membrane were determined in a low-activity cephalosporin C (cephC) producer Acremonium chrysogenum ATCC 11550 and selected highly efficient producer strain 26/8 grown on glucose or a synthetic medium providing for active synthesis of this antibiotic. It was shown that strain 26/8 on the synthetic medium produced 26-fold higher amount of cephC as compared with strain ATCC 11550. This was accompanied by a drastic decrease in the cell contents of ATP and the high-molecular-weight fractions polyP2, polyP3, and polyP5 with a concurrent increase in the low-molecular-weight fraction polyP1. These data suggest that polyPs are involved in the cephC synthesis as a source of energy. H⁺-ATPase activity insignificantly changed at both low and high levels of cephC production. This confirms the assumption that A. chrysogenum has other alternative antibiotic transporters in addition to cefT. The obtained results can be used for optimizing commercial-scale cephC biosynthesis.     

Gene structure,transcripts and calciotropic effects of the PTH family of peptides in <Emphasis Type="Italic">Xenopus</Emphasis> and chicken

Background  

Parathyroid hormone (PTH) and PTH-related peptide (PTHrP) belong to a family of endocrine factors that share a highly conserved N-terminal region (amino acids 1-34) and play key roles in calcium homeostasis, bone formation and skeletal development. Recently, PTH-like peptide (PTH-L) was identified in teleost fish raising questions about the evolution of these proteins. Although PTH and PTHrP have been intensively studied in mammals their function in other vertebrates is poorly documented. Amphibians and birds occupy unique phylogenetic positions, the former at the transition of aquatic to terrestrial life and the latter at the transition to homeothermy. Moreover, both organisms have characteristics indicative of a complex system in calcium regulation. This study investigated PTH family evolution in vertebrates with special emphasis on Xenopus and chicken.     

Effect of cycloheximide, iodoacetamide, and antimycin A on inorganic phosphate synthesis in Saccharomyces cerevisiae VKM Y-1173

The effect of inhibitors of protein synthesis (cycloheximide, CHI), glycolysis (iodoacetamide, IAA), and oxidative phosphorylation (antimycin A, ANM) on inorganic phosphate (polyP) synthesis during the first 0.5 h of their hypercompensation in Saccharomyces cerevisiae VKM Y-l173 grown on 2% glucose-containing media at low (hypoxia) or high aeration rates or in the presence of 1 vol % ethanol under high aeration conditions was studied. PolyP accumulation was highest in the medium with glucose under hypoxia; lower, with glucose at high aeration; and lowest, in the medium with ethanol. CHI had a small effect on the total polyP level but significantly stimulated ATP accumulation, irrespective of the culture growth conditions. The low-polymer acid-soluble polyP1 were synthesized most actively by the cells grown on glucose under hypoxia, alkali-soluble polyP3 were synthesized at en hanced aeration, and the most hig-molecular fraction, polyP5, was actively accumulated along with polyP3 at cultivation on ethanol. Regardless of the growth conditions, CHI inhibited accumulation of polyP4, the synthesis of which is associated with the synthesis of mannoproteins. IAA and ANM largely inhibited synthesis of all fractions at yeast growth under hypoxia and on ethanol, respectively. The results as a whole demonstrate the dependence of polyP formation on the main energy-generating cell processes and, at the same time, the absence of direct dependence of their synthesis on ATP concentration in Saccharomyces cerevisiae VKM Y-l 173.     

Unusual metastasis of papillary thyroid carcinoma to larynx and hypopharynx a case report

Background  

Although direct infiltration of papillary carcinoma of thyroid to larynx, trachea and esophagus is well recognized, lymphatic and vascular metastases to larynx and hypopharynx have rarely been reported.     

Dependence of inorganic polyphosphate chain length on the orthophosphate content in the culture medium of the yeast Saccharomyces cerevisiae

The content of inorganic linear polyphosphate (polyP) and the polymeric degree (n) of these compounds were determined in the process of growth of the yeast Saccharomyces cerevisiae VKM Y-1173 in a medium, which contained varying Pi amount with the constant level of all the necessary components. For this purpose, a combination of chemical methods of polyP extraction and 31P-NMR spectroscopy studies of their chain length were used. After 7 h of phosphate starvation, the yeast was shown to use almost completely the phosphate reserve in the form of polyP localized in various cell compartments to support their vitality. The polyP drop was followed by a considerable shortening of the polymer chain length of acid-soluble (polyP1) and two alkali-soluble (polyP3 and polyP4) fractions. Under the same conditions, the content of a salt-soluble fraction (polyP2) decreased almost 20-fold followed by a simultaneous increase of the chain length nearly 2-fold. As a result, fraction chain length ranged up to n = 40-45. Replacement of the yeast cells after phosphate starvation to a complete phosphate- and glucose-containing medium resulted in super-accumulation ("overcompensation") of polyP within 2 h mainly in polyP3 and, to a lesser degree, in polyP1, polyP2, and polyP5 fractions. In polyP4 fraction localized as polyP3 at the cell surface, the polyP super-accumulation was not detected. The increase of polyP amount in the fractions mentioned turned out not to be accompanied by simultaneous elongation of their chain length and occurred at the lowest level that is characteristic of a polymer level for each fraction. Further cultivation of the yeast on the complete medium during 2 h had little or no effect on polyP content in the cells but led to elongation of polyP chain length especially in the polyP3 and polyP4 fractions. A phenomenon of considerable elongation of polyP chain length against the background of their fixed content revealed in the yeast growing on the complete medium suggests that these organisms possess a previously unknown discrete way of polyP biosynthesis, which results first in the formation of comparatively low-molecular-mass chains followed by that of high-molecular-mass polymers.     

The effect of inactivation of the exo-and endopolyphosphatase genes PPX1 and PPN1 on the level of different polyphosphates in the yeast Saccharomyces cerevisiae

The inactivation of the PPX1 and PPN1 genes, which encode the major enzymes of polyphosphate degradation (exopolyphosphatase and endopolyphosphatase, respectively), was found to exert different effects on the content of different polyphosphates in the yeast Saccharomyces cerevisiae. The content of relatively low-molecular-weight acid-soluble polyphosphates in mutant yeast strains is inversely proportional to the exopolyphosphatase activity of the cytosol. At the same time, the mutation of these genes exerts no effect on salt-soluble polyphosphates. The content of high-molecular-weight alkali-soluble polyphosphates increases twofold in a mutant with inactivated genes of both exopolyphosphatase and endopolyphosphatase. The data obtained confirm the earlier suggestion that the metabolic pathways of particular polyphosphates in yeasts are different.     

Study of the content of inorganic polyphosphates in <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis> grown on different carbon sources with different O<Subscript>2</Subscript> concentrations in the medium

The content of different fractions of inorganic polyphosphates (polyP) was studied in Saccharomyces cerevisiae VKM Y-1173 growing on a complete medium with glucose under hypoxia and active aeration as well as on ethanol. The highest growth rate was observed for aerobic fermentation, while the yield of biomass was maximal for cultivation on ethanol. In the mid-log growth phase, the amount of poly P was maximal in the cells grown on glucose under hypoxia and minimal on ethanol. In this latter case, the content of different poly P fractions changed unevenly: polyP3, polyP4, and polyP1 decreased by approximately 60%, 45%, and 30%, respectively; the salt-soluble polyP2 remained at almost the same level; while polyP5 abruptly increased 10-to 15-fold. These findings demonstrate that the metabolic pathways for poly P fractions are different. A significant drop in the amount of the main poly P fractions accompanied by a decrease of the poly P average chain length in the presence of carbon and P_i sources in the medium is evidence of active involvement of poly P as additional energy sources in the flows of energy in actively growing yeast cells.