scholarly journals Kinetic Analysis of Growth Rate, ATP, and Pigmentation Suggests an Energy-Spilling Function for the Pigment Prodigiosin of Serratia marcescens

2008 ◽  
Vol 190 (22) ◽  
pp. 7453-7463 ◽  
Author(s):  
Pryce L. Haddix ◽  
Sarah Jones ◽  
Pratik Patel ◽  
Sarah Burnham ◽  
Kaori Knights ◽  
...  
Keyword(s):  
Stationary Phase ◽  
Serratia Marcescens ◽  
Growth Rates ◽  
High Growth ◽  
Atp Synthesis ◽  
Opportunistic Pathogen ◽  
Growth Conditions ◽  
Atp Production ◽  
Concentration Changes ◽  
Energy Spilling

ABSTRACTSerratia marcescensis a gram-negative environmental bacterium and opportunistic pathogen.S. marcescensexpresses prodigiosin, a bright red and cell-associated pigment which has no known biological function for producing cells. We present here a kinetic model relating cell, ATP, and prodigiosin concentration changes forS. marcescensduring cultivation in batch culture. Cells were grown in a variety of complex broth media at temperatures which either promoted or essentially prevented pigmentation. High growth rates were accompanied by large decreases in cellular prodigiosin concentration; low growth rates were associated with rapid pigmentation. Prodigiosin was induced most strongly during limited growth as the population transitioned to stationary phase, suggesting a negative effect of this pigment on biomass production. Mathematically, the combined rate of formation of biomass and bioenergy (as ATP) was shown to be equivalent to the rate of prodigiosin production. Studies with cyanide inhibition of both oxidative phosphorylation and pigment production indicated that rates of biomass and net ATP synthesis were actually higher in the presence of cyanide, further suggesting a negative regulatory role for prodigiosin in cell and energy production under aerobic growth conditions. Considered in the context of the literature, these results suggest that prodigiosin reduces ATP production by a process termed energy spilling. This process may protect the cell by limiting production of reactive oxygen compounds. Other possible functions for prodigiosin as a mediator of cell death at population stationary phase are discussed.

Associations Between Cellular Levels of ATP and Prodigiosin Pigment Throughout the Growth Cycle of Serratia marcescens

2021 ◽  
Author(s):  
Pryce L. Haddix
Keyword(s):  
Stationary Phase ◽  
Serratia Marcescens ◽  
Stationary Phases ◽  
Growth Cycle ◽  
High Density ◽  
High Rate ◽  
Lag Phase ◽  
Positive Role ◽  
Atp Production ◽  
Density Growth

ABSTRACT Serratia marcescens is a prolific producer of the red, membrane-associated pigment prodigiosin. Earlier work has established both a positive role for prodigiosin in ATP production during population lag phase and a negative role during high-rate, low cell density growth. This study uses the growth rate and growth phase modulation afforded by chemostat culture to extend prodigiosin functional analysis to the high density and stationary phases. Cellular levels of prodigiosin were positively associated with cellular levels of ATP during high-density growth, and artificial pigment induction during this phase increased cellular ATP. Following peak high density ATP per cell, early stationary phase enabled significant population growth while prodigiosin levels remained high and ATP declined. During late stationary phase, ATP per cell was positively associated with prodigiosin per cell while both declined during continued growth. These results provide correlational evidence for multiple effects of prodigiosin pigment on ATP production throughout the growth cycle. Earlier work and the data presented here enable formulation of a working model for the oscillating relationships between cellular levels of ATP and prodigiosin during batch culture.

Effects of Solidification Parameters on Lamellar Microstructures of Near Eutectic Cr-Cr3Si Alloys

2002 ◽  
Vol 753 ◽  
Author(s):  
H. Bei ◽  
E. P. George ◽  
G. M. Pharr
Keyword(s):  
Growth Rates ◽  
Solidification Rate ◽  
High Growth ◽  
Lamellar Spacing ◽  
Growth Conditions ◽  
Limited Range ◽  
Lamellar Structures ◽  
Wide Range ◽  
Solidification Parameters ◽  
Very High

ABSTRACTDirectional solidification of Cr-Cr3Si eutectic alloys has been carried out using a high temperature optical floating zone furnace. Uniform and well-aligned lamellar structures were obtained over a fairly wide range of intermediate growth rates but not at very low or very high growth rates where degenerate and cellular structures, respectively, were obtained. The lamellar spacing was found to increase with decreasing solidification rate, in agreement with the Jackson-Hunt theory. In addition, for a fixed growth rate, the lamellar spacing was found to increase with increasing rotation rate. Lamellar structures could also be produced at off-eutectic compositions, but only for a limited range of growth conditions. The Cr-rich lamellae are effective in stopping indention cracks nucleated in the brittle Cr3Si phase.

scholarly journals Regulation of Serratia marcescens ompF and ompC porin genes in response to osmotic stress, salicylate, temperature and pH

Microbiology ◽  
2006 ◽  
Vol 152 (2) ◽  
pp. 485-491 ◽  
Author(s):  
Sanela Begic ◽  
Elizabeth A. Worobec
Keyword(s):  
Antibiotic Resistance ◽  
Serratia Marcescens ◽  
Growth Temperature ◽  
High Growth ◽  
Opportunistic Pathogen ◽  
Translation Regulation ◽  
Lower Growth ◽  
Porin Proteins ◽  
Outer Membrane Permeability ◽  
High Degree

Serratia marcescens is a Gram-negative enterobacterium that has become an important opportunistic pathogen, largely due to its high degree of natural antibiotic resistance. One factor contributing to this natural antibiotic resistance is reduced outer membrane permeability, which is controlled in part by OmpC and OmpF porin proteins. OmpF expression is regulated by micF, an RNA transcript encoded upstream of the ompC gene, which hybridizes with the ompF transcript to inhibit its translation. Regulation of S. marcescens porin gene expression, as well as that of micF, was investigated using β-galactosidase reporter gene fusions in response to 5, 8 and 10 % sucrose, 1, 5 and 8 mM salicylate, and different pH and temperature values. β-Galactosidase activity assays revealed that a lower growth temperature (28 °C), a more basic pH (pH 8), and an absence of sucrose and salicylate induce the transcription of the ompF gene, whereas the induction of ompC is stimulated at a higher growth temperature (42 °C), acidic pH (pH 6), and maximum concentrations of sucrose (10 %) and salicylate (8 mM). In addition, when multiple conditions were tested, temperature had the predominant effect, followed by pH. In this study, it was found that the MicF regulatory mechanism does not play a role in the osmoregulation of the ompF and ompC genes, whereas MicF does repress OmpF expression in the presence of salicylate and high growth temperature, and under low pH conditions.

GROWTH OF PIKE-PERCH SANDER LUCIOPERCA (L., 1758) (PERCIDAE) IN RESERVOIRS OF K. SATPAYEV’S CHANNEL

2018 ◽  
pp. 59-68
Author(s):  
Saule Zhangirovna Asylbekova ◽  
Kuanysh Baibulatovich Isbekov ◽  
Vladimir Nickolaevich Krainyuk
Keyword(s):  
Growth Rates ◽  
Growth Dynamics ◽  
High Growth ◽  
Water Bodies ◽  
Volga River ◽  
Trophic Resources ◽  
Pike Perch ◽  
The Amur River ◽  
Back Calculation ◽  
Abiotic And Biotic Factors

Pike-perch is an invader for the water basins of Central Kazakhstan. These species have stable self-reproductive populations in the regional waters. Back calculation method was used to investigate pike-perch growth rates in reservoirs of K. Satpayev’s channel. For comparison, the data from the other water bodies (Vyacheslavsky and Sherubay-Nurinsky water reservoirs) were used, as well as literature data. Pike-perch species from the investigated waters don’t show high growth rates. The populations from the reservoirs of K. Satpayev’s channel have quite similar growth rates with populations from the Amur river, from a number of reservoirs in the Volga river basin and from the reservoir in Spain. Sexual differences in growth have not been observed. Evaluating possible influence of various abiotic and biotic factors on the growth rate of pike-perch in the reservoirs of K. Satpayev’s channel was carried out. It has been stated that the availability of trophic resources cannot play a key role in growth dynamics because of their high abundance. Morphology of water bodies also does not play a role, as well as chromaticity, turbidity and other optical water indicators. It can be supposed that the main factor influencing growth of pike perch is the habitat’s temperature. This factor hardly ever approaches optimal values for the species in reservoirs of K. Satpaev’s channel. The possible influence of fishing selectivity on pike-perch growth rates was also evaluated. Currently, there has been imposed a moratorium on pike-perch catch. However, pike-perch is found in by-catches and in catches of amateur fishermen. It should be said that such seizures have an insignificant role in the dynamics of growth rates.

scholarly journals Human Trisomic iPSCs from Down Syndrome Fibroblasts Manifest Mitochondrial Alterations Early during Neuronal Differentiation

Biology ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 609
Author(s):  
Nunzia Mollo ◽  
Matteo Esposito ◽  
Miriam Aurilia ◽  
Roberta Scognamiglio ◽  
Rossella Accarino ◽  
...  
Keyword(s):  
Down Syndrome ◽  
Mitochondrial Dysfunction ◽  
Neuronal Differentiation ◽  
Expression Profiles ◽  
Meta Analysis ◽  
Atp Synthesis ◽  
Differentiation Markers ◽  
Differentiation Potential ◽  
Atp Production ◽  
Mitochondrial Alterations

Background: The presence of mitochondrial alterations in Down syndrome suggests that it might affect neuronal differentiation. We established a model of trisomic iPSCs, differentiating into neural precursor cells (NPCs) to monitor the occurrence of differentiation defects and mitochondrial dysfunction. Methods: Isogenic trisomic and euploid iPSCs were differentiated into NPCs in monolayer cultures using the dual-SMAD inhibition protocol. Expression of pluripotency and neural differentiation genes was assessed by qRT-PCR and immunofluorescence. Meta-analysis of expression data was performed on iPSCs. Mitochondrial Ca2+, reactive oxygen species (ROS) and ATP production were investigated using fluorescent probes. Oxygen consumption rate (OCR) was determined by Seahorse Analyzer. Results: NPCs at day 7 of induction uniformly expressed the differentiation markers PAX6, SOX2 and NESTIN but not the stemness marker OCT4. At day 21, trisomic NPCs expressed higher levels of typical glial differentiation genes. Expression profiles indicated that mitochondrial genes were dysregulated in trisomic iPSCs. Trisomic NPCs showed altered mitochondrial Ca2+, reduced OCR and ATP synthesis, and elevated ROS production. Conclusions: Human trisomic iPSCs can be rapidly and efficiently differentiated into NPC monolayers. The trisomic NPCs obtained exhibit greater glial-like differentiation potential than their euploid counterparts and manifest mitochondrial dysfunction as early as day 7 of neuronal differentiation.

scholarly journals Carbon and Nitrogen Sources Have No Impact on the Organization and Composition of Ustilago maydis Respiratory Supercomplexes

2021 ◽  
Vol 7 (1) ◽  
pp. 42
Author(s):  
Deyamira Matuz-Mares ◽  
Oscar Flores-Herrera ◽  
Guadalupe Guerra-Sánchez ◽  
Lucero Romero-Aguilar ◽  
Héctor Vázquez-Meza ◽  
...  
Keyword(s):  
Atp Synthase ◽  
Polyacrylamide Gel Electrophoresis ◽  
Atp Synthesis ◽  
Nitrogen Sources ◽  
Growth Conditions ◽  
Energy Conditions ◽  
Respiratory Complexes ◽  
Respiratory Supercomplexes ◽  
Nadh Dehydrogenases ◽  
Reduced Nicotinamide Adenine Dinucleotide

Respiratory supercomplexes are found in mitochondria of eukaryotic cells and some bacteria. A hypothetical role of these supercomplexes is electron channeling, which in principle should increase the respiratory chain efficiency and ATP synthesis. In addition to the four classic respiratory complexes and the ATP synthase, U. maydis mitochondria contain three type II NADH dehydrogenases (NADH for reduced nicotinamide adenine dinucleotide) and the alternative oxidase. Changes in the composition of the respiratory supercomplexes due to energy requirements have been reported in certain organisms. In this study, we addressed the organization of the mitochondrial respiratory complexes in U. maydis under diverse energy conditions. Supercomplexes were obtained by solubilization of U. maydis mitochondria with digitonin and separated by blue native polyacrylamide gel electrophoresis (BN-PAGE). The molecular mass of supercomplexes and their probable stoichiometries were 1200 kDa (I1:IV1), 1400 kDa (I1:III2), 1600 kDa (I1:III2:IV1), and 1800 kDa (I1:III2:IV2). Concerning the ATP synthase, approximately half of the protein is present as a dimer and half as a monomer. The distribution of respiratory supercomplexes was the same in all growth conditions. We did not find evidence for the association of complex II and the alternative NADH dehydrogenases with other respiratory complexes.

Integration host factor alleviates H-NS silencing of the Salmonella enterica serovar Typhimurium master regulator of SPI1, hilA

Microbiology ◽  
2011 ◽  
Vol 157 (9) ◽  
pp. 2504-2514 ◽  
Author(s):  
Mário H. Queiroz ◽  
Cristina Madrid ◽  
Sònia Paytubi ◽  
Carlos Balsalobre ◽  
Antonio Juárez
Keyword(s):  
Stationary Phase ◽  
Salmonella Enterica ◽  
Growth Conditions ◽  
Integration Host Factor ◽  
Band Shift ◽  
Global Regulators ◽  
Serovar Typhimurium ◽  
Associated Proteins ◽  
Transcription Data

Coordination of the expression of Salmonella enterica invasion genes on Salmonella pathogenicity island 1 (SPI1) depends on a complex circuit involving several regulators that converge on expression of the hilA gene, which encodes a transcriptional activator (HilA) that modulates expression of the SPI1 virulence genes. Two of the global regulators that influence hilA expression are the nucleoid-associated proteins Hha and H-NS. They interact and form a complex that modulates gene expression. A chromosomal transcriptional fusion was constructed to assess the effects of these modulators on hilA transcription under several environmental conditions as well as at different stages of growth. The results obtained showed that these proteins play a role in silencing hilA expression at both low temperature and low osmolarity, irrespective of the growth phase. H-NS accounts for the main repressor activity. At high temperature and osmolarity, H-NS-mediated silencing completely ceases when cells enter the stationary phase, and hilA expression is induced. Mutants lacking IHF did not induce hilA in cells entering the stationary phase, and this lack of induction was dependent on the presence of H-NS. Band-shift assays and in vitro transcription data showed that for hilA induction under certain growth conditions, IHF is required to alleviate H-NS-mediated silencing.

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