scholarly journals Reduced ATP-dependent proteolysis of functional proteins during nutrient limitation speeds the return of microbes to a growth state

2021 ◽  
Vol 14 (667) ◽  
pp. eabc4235
Author(s):  
Jinki Yeom ◽  
Eduardo A. Groisman
Keyword(s):  
Stationary Phase ◽  
Nutrient Limitation ◽  
Rapid Growth ◽  
Slow Growth ◽  
Functional Protein ◽  
Growth State ◽  
Serovar Typhimurium ◽  
Speed Up ◽  
Protein Preservation ◽  
Nitrogen Conditions

When cells run out of nutrients, the growth rate greatly decreases. Here, we report that microorganisms, such as the bacterium Salmonella enterica serovar Typhimurium, speed up the return to a rapid growth state by preventing the proteolysis of functional proteins by ATP-dependent proteases while in the slow-growth state or stationary phase. This reduction in functional protein degradation resulted from a decrease in the intracellular concentration of ATP that was nonetheless sufficient to allow the continued degradation of nonfunctional proteins by the same proteases. Protein preservation occurred under limiting magnesium, carbon, or nitrogen conditions, indicating that this response was not specific to low availability of a particular nutrient. Nevertheless, the return to rapid growth required proteins that mediate responses to the specific nutrient limitation conditions, because the transcriptional regulator PhoP was necessary for rapid recovery only after magnesium starvation. Reductions in intracellular ATP and in ATP-dependent proteolysis also enabled the yeast Saccharomyces cerevisiae to recover faster from stationary phase. Our findings suggest that protein preservation during a slow-growth state is a conserved microbial strategy that facilitates the return to a growth state once nutrients become available.

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.

Human Foramen Magnum Area and Posterior Cranial Fossa Volume Growth in Relation to Cranial Base Synchondrosis Closure in the Course of Child Development

Neurosurgery ◽  
2016 ◽  
Vol 79 (5) ◽  
pp. 722-735 ◽  
Author(s):  
Guillaume Coll ◽  
Jean-Jacques Lemaire ◽  
Federico Di Rocco ◽  
Isabelle Barthélémy ◽  
Jean-Marc Garcier ◽  
...  
Keyword(s):  
Rapid Growth ◽  
Slow Growth ◽  
Volume Growth ◽  
Cranial Base ◽  
Foramen Magnum ◽  
Posterior Cranial Fossa ◽  
Healthy Children ◽  
Cranial Fossa ◽  
The Mean ◽  
Tomography Scan

Abstract BACKGROUND: To date, no study has compared the evolution of the foramen magnum area (FMA) and the posterior cranial fossa volume (PCFV) with the degree of cranial base synchondrosis ossification. OBJECTIVE: To illustrate these features in healthy children. METHODS: The FMA, the PCFV, and the ossification of 12 synchondroses according to the Madeline and Elster scale were retrospectively analyzed in 235 healthy children using millimeter slices on a computed tomography scan. RESULTS: The mean FMA of 6.49 cm2 in girls was significantly inferior to the FMA of 7.67 cm2 in boys (P <.001). In both sexes, the growth evolved in a 2-phase process, with a phase of rapid growth from birth to 3.75 years old (yo) followed by a phase of stabilization. In girls, the first phase was shorter (ending at 2.6 yo) than in boys (ending at 4.33 yo) and proceeded at a higher rate. PCFV was smaller in girls (P <.001) and displayed a biphasic pattern in the whole population, with a phase of rapid growth from birth to 3.58 yo followed by a phase of slow growth until 16 yo. In girls, the first phase was more active and shorter (ending at 2.67 yo) than in boys (ending at 4.5 yo). The posterior interoccipital synchondroses close first, followed by the anterior interoccipital and occipitomastoidal synchondroses, the lambdoid sutures simultaneously, then the petro-occipital and spheno-occipital synchondroses simultaneously. CONCLUSION: The data provide a chronology of synchondrosis closure. We showed that FMA and PCFV are constitutionally smaller in girls at birth (P ⩽.02) and suggest that a sex-related difference in the FMA is related to earlier closure of anterior interoccipital synchondroses in girls (P =.01).

Diversité morphologique en culture, sensibilité au carbendazime et pouvoir pathogène du Tapesia yallundae (anamorphe : Pseudocercosporella herpotrichoides)

1995 ◽  
Vol 73 (9) ◽  
pp. 1379-1384 ◽  
Author(s):  
Peter Frei ◽  
Daniel Gindrat
Keyword(s):  
Growth Rate ◽  
Triticum Aestivum ◽  
Hordeum Vulgare ◽  
Rapid Growth ◽  
Slow Growth ◽  
Colony Growth ◽  
Sexual Stage ◽  
Pseudocercosporella Herpotrichoides ◽  
Tapesia Yallundae ◽  
Irregular Margin

Three types of colonies (WH, WA, and RA) have been characterized among 2245 isolates of Pseudocercosporella herpotrichoides on the basis of colony growth rate and appearance (W, rapid growth and regular margin; R, slow growth and irregular margin) and of the shape of the majority of conidia (H, coiled; A, straight). Apothecia of Tapesia yallundae (anamorph : P. herpotrichoides) were produced on naturally infected stems of winter wheat and barley. Apothecia of an undetermined discomycete were occasionally observed. The progeny of more than 1700 ascospores from 72 apothecia of T. yallundae was distributed among the three types of colonies. These types remained stable through successive conidial and mycelial subcultures. All three colony types were sometimes obtained from a single apothecium. WH and WA were the most common, while RH was never observed. WA isolates were more often resistant than WH isolates to carbendazim. Inoculations of wheat and barley stems with ascospores of T. yallundae were unsuccessful, while inoculations with conidia or mycelium resulted in eyespot lesions. During equivalent periods, RA isolates were less virulent than WH and WA. Key words: cereals, eyespot, Deuteromycetes, sexual stage, Hordeum vulgare, Triticum aestivum.

scholarly journals Respective Roles of Culturable and Viable-but-Nonculturable Cells in the Heterogeneity of Salmonella enterica Serovar Typhimurium Invasiveness

2009 ◽  
Vol 75 (16) ◽  
pp. 5179-5185 ◽  
Author(s):  
Julien Passerat ◽  
Patrice Got ◽  
Sam Dukan ◽  
Patrick Monfort
Keyword(s):  
Stationary Phase ◽  
Salmonella Enterica ◽  
Gradient Centrifugation ◽  
Health Concern ◽  
Viable But Nonculturable ◽  
Serovar Typhimurium ◽  
Nonculturable Cells ◽  
Sources Of Infection ◽  
Culturable Cell ◽  
Vbnc Cell

ABSTRACT The existence of Salmonella enterica serovar Typhimurium viable-but-nonculturable (VBNC) cells is a public health concern since they could constitute unrecognized sources of infection if they retain their pathogenicity. To date, many studies have addressed the ability of S. Typhimurium VBNC cells to remain infectious, but their conclusions are conflicting. An assumption could explain these conflicting results. It has been proposed that infectivity could be retained only temporarily after entry into the VBNC state and that most VBNC cells generated under intense stress could exceed the stage where they are still infectious. Using a Radioselectan density gradient centrifugation technique makes it possible to increase the VBNC-cell/culturable-cell ratio without increasing the exposure to stress and, consequently, to work with a larger proportion of newly VBNC cells. Here, we observed that (i) in the stationary phase, the S. Typhimurium population comprised three distinct subpopulations at 10, 24, or 48 h of culture; (ii) the VBNC cells were detected at 24 and 48 h; (iii) measurement of invasion gene (hilA, invF, and orgA) expression demonstrated that cells are highly heterogeneous within a culturable population; and (iv) invasion assays of HeLa cells showed that culturable cells from the different subpopulations do not display the same invasiveness. The results also suggest that newly formed VBNC cells are either weakly able or not able to successfully initiate epithelial cell invasion. Finally, we propose that at entry into the stationary phase, invasiveness may be one way for populations of S. Typhimurium to escape stochastic alteration leading to cell death.

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