scholarly journals Modelling the Efficacy of Febrile Heating in Infected Endotherms

2021 ◽  
Vol 9 ◽  
Author(s):  
Gregory Lewis ◽  
Michael B. Bonsall
Keyword(s):  
Body Temperature ◽  
Antimicrobial Effect ◽  
Optimal Growth ◽  
Absolute Temperature ◽  
Continuous Heating ◽  
Temperature Dependent ◽  
Simple Physical Model ◽  
Direct Growth ◽  
Dependent Growth ◽  
Body Temperature Increase

Fever is a response to infection characterised by an increase in body temperature. The adaptive value of this body temperature increase for endotherms is unclear, given the relatively small absolute temperature increases associated with endotherm fever, its substantial metabolic costs, and the plausibility for pathogens to adapt to higher temperatures. We consider three thermal mechanisms for fever's antimicrobial effect: (1) direct growth inhibition by elevating temperature above the pathogens optimal growth temperature; (2) further differentiating the host body from the wider environment; and (3) through increasing thermal instability of the pathogen environment. We assess these by modelling their effects pathogen on temperature dependent growth, finding thermal effects can vary from highly to minimally effective depending on pathogen species. We also find, depending on the specification of a simple physical model, intermittent heating can inhibit pathogen growth more effectively than continuous heating with an energy constraint.

scholarly journals The Legionella Lqs-LvbR regulatory network controls temperature-dependent growth onset and bacterial cell density

2021 ◽  
Author(s):  
Ramon Hochstrasser ◽  
Hubert Hilbi
Keyword(s):  
Cell Density ◽  
Legionella Pneumophila ◽  
Elevated Temperatures ◽  
Optimal Growth ◽  
Lag Phase ◽  
Temperature Dependent ◽  
Genes Encoding ◽  
Life Threatening ◽  
Cell Densities ◽  
Dependent Growth

Legionella species are facultative intracellular pathogens, which can cause a life-threatening pneumonia termed Legionnaires’ disease. Legionella pneumophila employs the Legionella quorum sensing (Lqs)-LvbR network to regulate virulence and motility, but its role for growth in media is ill-defined. Compared to the parental L. pneumophila strain JR32, a ΔlqsR mutant showed a reduced lag phase at 30°C and reached a higher cell density at 45°C, while the ΔlqsA, ΔlqsS and ΔlqsT mutants exhibited a longer lag phase and reached only a lower cell density. A ΔlvbR mutant resumed growth like the parental strain at 30°C, but exhibited a substantially reduced cell density at 45°C. Thus, LvbR is an important cell density regulator at elevated temperatures. A quantitative analysis of temperature-dependent growth characteristics of environmental and clinical strains revealed that L. pneumophila strains grew in AYE medium after distinct lag phases with similar rates at 30°C, reached different cell densities at the optimal growth temperature of 40°C, and no longer grew at 50°C. Legionella longbeachae reached a rather low cell density at 40°C and did not grow at and beyond 45°C. Genes encoding components of the Lqs-LvbR network were present in the genomes of the environmental and clinical L. pneumophila isolates, and the PlqsR, PlqsA, PlqsS and PlvbR promoters from strain JR32 were active in these strains. Taken together, our results indicate that the Lqs-LvbR network governs the temperature-dependent growth onset and cell density of the L. pneumophila reference strain JR32, and possibly also of environmental and clinical L. pneumophila isolates.

KEX2 mutations suppress RNA polymerase II mutants and alter the temperature range of yeast cell growth

1989 ◽  
Vol 9 (6) ◽  
pp. 2341-2349
Author(s):  
C Martin ◽  
R A Young
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Single Gene ◽  
Yeast Cells ◽  
Temperature Sensitive ◽  
Temperature Dependent ◽  
Growth Properties ◽  
Cold Sensitive ◽  
Dependent Growth ◽  
Kex2 Protease

Suppressors of a temperature-sensitive RNA polymerase II mutation were isolated to identify proteins that interact with RNA polymerase II in yeast cells. Ten independently isolated extragenic mutations that suppressed the temperature-sensitive mutation rpb1-1 and produced a cold-sensitive phenotype were all found to be alleles of a single gene, SRB1. An SRB1 partial deletion mutant was further investigated and found to exhibit several pleiotropic phenotypes. These included suppression of numerous temperature-sensitive RNA polymerase II mutations, alteration of the temperature growth range of cells containing wild-type RNA polymerase, and sterility of cells of alpha mating type. The ability of SRB1 mutations to suppress the temperature-sensitive phenotype of RNA polymerase II mutants did not extend to other temperature-sensitive mutants investigated. Isolation of the SRB1 gene revealed that SRB1 is KEX2. These results indicate that the KEX2 protease, whose only known substrates are hormone precursors, can have an important influence on RNA polymerase II and the temperature-dependent growth properties of yeast cells.

Pythium myriotylum is recovered most frequently from Pythium soft-rot infected ginger rhizomes in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Paul Daly ◽  
Yifan Chen ◽  
Qimeng Zhang ◽  
Hongli Zhu ◽  
Jingjing Li ◽  
...  
Keyword(s):  
Severe Disease ◽  
Zingiber Officinale ◽  
Soft Rot ◽  
Temperature Dependent ◽  
Pythium Myriotylum ◽  
Disease Symptoms ◽  
Ginger Rhizome ◽  
Oomycete Pathogen ◽  
Dependent Growth ◽  
Pythium Soft Rot

Pythium soft rot is a major soil-borne disease of crops such as ginger (Zingiber officinale). Our objective was to identify which Pythium species were associated with Pythium soft-rot of ginger in China, where approximately 20% of global ginger production is from. Oomycetes infecting ginger rhizomes from seven provinces were investigated using two molecular markers, the internal transcribed spacer (ITS) and cytochrome c oxidase subunit II (CoxII). In total, 81 isolates were recovered and approximately 95% of the isolates were identified as Pythium myriotylum and the other isolates were identified as either P. aphanidermatum or P. graminicola. Notably, the P. myriotylum isolates from China did not contain the SNP in the CoxII sequence found previously in the P. myriotylum isolates infecting ginger in Australia. A subset of 36 of the isolates was analyzed repeatedly by temperature-dependent growth, severity of disease on ginger plants and aggressiveness of colonization of ginger rhizome sticks. In the pathogenicity assays, 32/36 of the isolates were able to significantly infect and cause severe disease symptoms on the ginger plants. A range of temperature-dependent growth, disease severity and aggressiveness in colonization was found with a significant moderate positive correlation between growth and aggressiveness of colonization of the ginger sticks. This study identified P. myriotylum as the major oomycete pathogen in China from infected ginger rhizomes and suggests that P. myriotylum should be a key target to control soft rot of ginger disease.

Mechanism Investigation of Temperature Dependent Growth and Etching Process of GeCl4 on SiGe Surface: ab-initio Study

2021 ◽  
Author(s):  
Ji Young Park ◽  
Gyeom Kim ◽  
Jin Bum Kim ◽  
Sang-Moon Lee ◽  
Sae-jin Kim ◽  
...  
Keyword(s):  
Ab Initio ◽  
Etching Process ◽  
Ab Initio Study ◽  
Temperature Dependent ◽  
Dependent Growth

Catecholamine elevation in iron deficiency

1979 ◽  
Vol 237 (5) ◽  
pp. R297-R300 ◽  
Author(s):  
E. Dillmann ◽  
D. G. Johnson ◽  
J. Martin ◽  
B. Mackler ◽  
C. Finch
Keyword(s):  
Body Temperature ◽  
Body Temperatures ◽  
Temperature Dependent ◽  
Urinary Catecholamines ◽  
Threefold Increase ◽  
Iron Deficient ◽  
Catecholamine Response ◽  
The Difference ◽  
And Control ◽  
Maintain Body Temperature

Iron-deficient rats have increased blood and urinary catecholamines regardless of whether anemia is or is not present. The catecholamine response in both iron-deficient and control animals is largely temperature dependent, showing little difference at the isothermic temperature of 30 degrees C but a two- to threefold increase in iron-deficient animals over controls at lower temperatures. The iron-deficient rat is unable to maintain body temperature at 4 degrees C and this is independent of anemia or of food intake. When animals are run on the treadmill for 4 h, body temperatures increase but the difference observed at 4 degrees C between iron-deficient and control animals persists. The underlying abnormality in temperature regulation and in catecholamine response disappeared after 6 days of iron therapy.

Temperature-dependent growth and hypericin biosynthesis in Hypericum perforatum

2019 ◽  
Vol 139 ◽  
pp. 613-619
Author(s):  
Yuanyuan Yao ◽  
Tianlan Kang ◽  
Ling Jin ◽  
Zihan Liu ◽  
Zhen Zhang ◽  
...  
Keyword(s):  
Hypericum Perforatum ◽  
Temperature Dependent ◽  
Dependent Growth

Analysis of soft impingement in nonisothermal precipitation

2009 ◽  
Vol 24 (12) ◽  
pp. 3664-3673 ◽  
Author(s):  
Kai Fan ◽  
Feng Liu ◽  
Wei Yang ◽  
Gencang Yang ◽  
Yaohe Zhou
Keyword(s):  
Three Dimensional ◽  
Plain Carbon Steel ◽  
Model Parameters ◽  
Temperature Dependent ◽  
Analytical Treatment ◽  
Growth Coefficient ◽  
Soft Impingement ◽  
Compact Expression ◽  
Nonisothermal Heating ◽  
Dependent Growth

The effects of soft impingement on precipitation are considered. A physically realistic analytical treatment of soft impingement has been developed for solid-state precipitation in a nonisothermal heating/cooling process following the basic assumptions (i.e., a two-stage transformation including site saturation of nucleation, isotropic growth and linear approximation for a concentration gradient in front of the precipitate/matrix interface). Furthermore, both one- and three-dimensional precipitations have been described using a compact expression which is analogous to Zener’s model but with a temperature-dependent growth coefficient. A detailed description for the model parameters has been given for the model application. Good agreement with published experimental data, for example, the decomposition of austenite in a 0.038–0.30wt%Mn plain carbon steel, has been achieved.

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