scholarly journals Heat Shock Modulates The Expression of Sirtuins and Var Genes in The Malaria Parasite Plasmodium Falciparum

2020 ◽  
Author(s):  
Linda O. Anagu ◽  
David R. Hulse ◽  
Srabasti J Chakravorty ◽  
Paul D. Horrocks ◽  
Catherine Jill Merrick
Keyword(s):  
Gene Expression ◽  
Plasmodium Falciparum ◽  
Heat Stress ◽  
Heat Shock ◽  
Malaria Parasite ◽  
Severe Disease ◽  
Expression Patterns ◽  
Stress Factors ◽  
High Expression ◽  
Human Host

Abstract Background: In the malaria parasite Plasmodium falciparum the expression of ‘var’ virulence genes is regulated through epigenetic mechanisms. Two deacetylase enzymes of the sirtuin family have been implicated in this epigenetic control in laboratory-adapted parasites. A previous study of var gene expression in parasites isolated directly from Gambian malaria patients found that high expression levels of severe-disease-associated var variants correlated with high expression of the PfSir2A sirtuin, and these expression patterns also correlated with patient phenotypes of fever and hyperlactataemia. Together, the observations suggest a mechanism through which stress phenotypes in the human host might be sensed via a parasite sirtuin, and virulence gene expression modulated accordingly. Methods: In vitro experiments were conducted using recently-laboratory-adapted Kenyan isolates of P. falciparum to follow up the correlative findings of the field study. To investigate a potential cause-and-effect relationship between host stress factors and parasite gene expression, qPCR was used to measure the expression of sirtuins and var genes after cultured parasites had been exposed to 2h or 6h of heat shock at 40°C or elevated lactate at 5mM.Results: Heat shock was shown to influence the expression of both sirtuins and var genes, whereas exposure to lactate was not. Heat shock in the trophozoite stage resulted in modest upregulation of the expression of sirtuins, particularly PfSir2B, by 2-3 fold in all strains tested. Interestingly, when heat shock was applied in ring stages PfSir2A was still upregulated but PfSir2B was downregulated. This correlated with a general upregulation of ring-stage var transcription, and particularly of severe-disease-associated upsA and upsB var genes, but there was no clear pattern in the dominant var gene(s) ultimately expressed by heat-shocked parasites. Conclusions: This study demonstrates for the first time that heat stress in recently-laboratory-adapted isolates of P. falciparum results in altered sirtuin expression – PfSir2B as well as PfSir2A – and also the upregulation of var gene expression. These may be strategies evolved by the parasite to survive heat stress when a human host experiences malarial fevers. By contrast, the association between hyperlactataemia and sirtuin/var gene expression that was previously observed in vivo appears to be coincidental rather than causative.

scholarly journals Heat shock modulates the expression of sirtuins and var genes in the malaria parasite Plasmodium falciparum

2020 ◽  
Author(s):  
Linda Anagu ◽  
David Hulse ◽  
Srabasti Chakravorty ◽  
Paul Horrocks ◽  
Catherine Jill Merrick
Keyword(s):  
Gene Expression ◽  
Plasmodium Falciparum ◽  
Heat Stress ◽  
Heat Shock ◽  
Malaria Parasite ◽  
Severe Disease ◽  
Expression Patterns ◽  
Stress Factors ◽  
High Expression ◽  
Human Host

Abstract Background: In the malaria parasite Plasmodium falciparum the expression of key ‘var’ virulence genes is regulated through epigenetic mechanisms. Two deacetylase enzymes of the sirtuin family have been implicated in this epigenetic control in laboratory-adapted parasites. A previous study of var gene expression in parasites isolated directly from Gambian malaria patients found that high expression levels of severe-disease-associated var variants correlated with high expression of the PfSir2A sirtuin, and these expression patterns also correlated with patient phenotypes of fever and hyperlactataemia. Together, the observations suggest a mechanism through which stress phenotypes in the human host might be sensed via a parasite sirtuin, and virulence gene expression modulated accordingly. Methods: In vitro experiments were conducted using recently-laboratory-adapted Kenyan isolates of P. falciparum to follow up the correlative findings of the field study. To investigate a potential cause-and-effect relationship between host stress factors and parasite gene expression, RT-PCR was used to measure the expression of sirtuins and var genes after cultured parasites had been exposed to 2h or 6h of heat shock at 40°C or elevated lactate at 5mM.Results: Heat shock was shown to influence the expression of both sirtuins and var genes, whereas exposure to lactate was not. Heat shock in the trophozoite stage resulted in modest upregulation of the expression of sirtuins, particularly PfSir2B, by 2-3 fold in all strains tested. Interestingly, when heat shock was applied in ring stages PfSir2A was still upregulated but PfSir2B was downregulated. This correlated with a general upregulation of ring-stage var transcription, and particularly of severe-disease-associated upsA and upsB var genes, but there was no clear pattern in the dominant var gene(s) ultimately expressed by heat-shocked parasites. Conclusions: This study demonstrates for the first time that heat stress in recently-laboratory-adapted patient isolates of P. falciparum results in altered sirtuin expression – PfSir2B as well as PfSir2A – and also the upregulation of var gene expression. These may be strategies evolved by the parasite to survive heat stress when a human host experiences malarial fevers. By contrast, the association between hyperlactataemia and sirtuin/var gene expression that was previously observed in vivo appears to be coincidental rather than causative.

scholarly journals Modulation of the expression of sirtuins and var genes by heat shock in the malaria parasite Plasmodium falciparum: a pattern emerges

2021 ◽  
Author(s):  
Linda O. Anagu ◽  
David R. Hulse ◽  
Paul D. Horrocks ◽  
Srabasti J Chakravorty
Keyword(s):  
Gene Expression ◽  
Plasmodium Falciparum ◽  
Heat Shock ◽  
Malaria Parasite ◽  
Severe Disease ◽  
Expression Patterns ◽  
Stress Factors ◽  
Virulence Gene Expression

Abstract Background: In the malaria parasite Plasmodium falciparum the expression of ‘var’ virulence genes is regulated through epigenetic mechanisms. Its sirtuin epigenetic regulators have a direct effect on var gene expression patterns, are increased in a laboratory strain of P. falciparum exposed to heat shock and are positively associated with fever. A Gambia study extended this association to blood lactate and var genes commonly expressed in severe malaria, and between PfSir2A and group B var. A Kenyan study extended this association to between PfSir2A and overall var transcript level. These observations suggest a mechanism through which stress phenotypes in the human host might be sensed via a parasite sirtuin, and virulence gene expression modulated accordingly. Methods: In vitro experiments were conducted using laboratory and recently-laboratory-adapted Kenyan isolates of P. falciparum to follow up the correlative findings of the field study. To investigate a potential cause-and-effect relationship between host stress factors and parasite gene expression, qPCR was used to measure the expression of sirtuins and var genes after highly synchronous cultured parasites had been exposed to 2h or 6h of heat shock at 40°C or elevated lactate.Results: Heat shock was shown to influence the expression of PfSir2B in the trophozoites, whereas exposure to lactate was not. After the ring stages were exposed to heat shock; sirtuins, severe-disease-associated upsA and upsB var genes and var genes in general were not altered. More biological replicate experiments will be needed to confirm our observations. Conclusions: This study demonstrates that heat stress in laboratory and recently-laboratory-adapted isolates of P. falciparum results in a small increase in PfSir2B transcripts in the trophozoite stages only. By contrast, the association between hyperlactataemia and sirtuin/var gene expression that was previously observed in vivo appears to be coincidental rather than causative.

scholarly journals Alteration of the expression of sirtuins and var genes by heat shock in the malaria parasite Plasmodium falciparum: a pattern emerges

2021 ◽  
Author(s):  
Linda O. Anagu ◽  
David R. Hulse ◽  
Paul D. Horrocks ◽  
Srabasti J Chakravorty
Keyword(s):  
Gene Expression ◽  
Plasmodium Falciparum ◽  
Heat Shock ◽  
Blood Lactate ◽  
Malaria Parasite ◽  
Severe Disease ◽  
Expression Patterns ◽  
Stress Factors

Abstract Background In the malaria parasite Plasmodium falciparum the expression of ‘var’ virulence genes is regulated through epigenetic mechanisms. P. falciparum sirtuin epigenetic regulators have a direct effect on their var gene expression patterns, are increased in the 3D7 laboratory strain on exposure to heat shock. A Gambia study showed an association with fever, blood lactate and var genes commonly expressed in severe malaria, and between PfSir2A and group B var. A Kenyan study extended this association to between PfSir2A and overall var transcript level. We investigated a causal link between heat shock or lactate levels and sirtuins or var expression. Methods In vitro experiments were conducted using laboratory and recently-laboratory-adapted Kenyan isolates of P. falciparum to follow up the correlative findings of the field study. To investigate a potential cause-and-effect relationship between host stress factors and parasite gene expression, qPCR was used to measure the expression of sirtuins and var genes after highly synchronous cultured parasites had been exposed to 2h or 6h of heat shock at 40°C or elevated lactate. Results Heat shock was shown to increase the expression of PfSir2B in the trophozoites, whereas exposure to lactate was not. After the ring stages were exposed to heat shock and lactate, there was no alteration in the expression of sirtuins and severe-disease-associated upsA and upsB var genes. The association between high blood lactate and sirtuin/var gene expression that was previously observed in vivo appears to be coincidental rather than causative. Conclusions This study demonstrates that heat stress in laboratory and recently-laboratory-adapted isolates of P. falciparum results in a small increase in PfSir2B transcripts in the trophozoite stages only. This finding adds to our understanding of how patient factors can influence the outcome of Plasmodium falciparum infections.

scholarly journals Modulation of the expression of sirtuins and var genes by heat shock in the malaria parasite Plasmodium falciparum: a pattern emerges

2021 ◽  
Author(s):  
Linda O. Anagu ◽  
David R. Hulse ◽  
Paul D. Horrocks ◽  
Srabasti J Chakravorty
Keyword(s):  
Gene Expression ◽  
Plasmodium Falciparum ◽  
Heat Shock ◽  
Malaria Parasite ◽  
Severe Disease ◽  
Expression Patterns ◽  
Stress Factors ◽  
Virulence Gene Expression

Abstract Background: In the malaria parasite Plasmodium falciparum the expression of ‘var’ virulence genes is regulated through epigenetic mechanisms. Its sirtuin epigenetic regulators have a direct effect on var gene expression patterns, are increased in a laboratory strain of P. falciparum exposed to heat shock and are positively associated with fever. A Gambia study extended this association to blood lactate and var genes commonly expressed in severe malaria, and between PfSir2A and group B var. A Kenyan study extended this association to between PfSir2A and overall var transcript level. These observations suggest a mechanism through which stress phenotypes in the human host might be sensed via a parasite sirtuin, and virulence gene expression modulated accordingly. Methods: In vitro experiments were conducted using laboratory and recently-laboratory-adapted Kenyan isolates of P. falciparum to follow up the correlative findings of the field study. To investigate a potential cause-and-effect relationship between host stress factors and parasite gene expression, qPCR was used to measure the expression of sirtuins and var genes after highly synchronous cultured parasites had been exposed to 2h or 6h of heat shock at 40°C or elevated lactate.Results: Heat shock was shown to influence the expression of PfSir2B in the trophozoites, whereas exposure to lactate was not. After the ring stages were exposed to heat shock, sirtuins, severe-disease-associated upsA and upsB var genes and var genes in general were not altered. More biological replicate experiments will be needed to confirm our observations.Conclusions: This study demonstrates that heat stress in laboratory and recently-laboratory-adapted isolates of P. falciparum results in a small increase in PfSir2B transcripts in the trophozoite stages only. We could not establish if heat shock can cause an increased expression of sirtuins or var genes in the ring stages. By contrast, the association between hyperlactataemia and sirtuin/var gene expression that was previously observed in vivo appears to be coincidental rather than causative.

scholarly journals De Novo Transcriptome Analysis Reveals Potential Thermal Adaptation Mechanisms in the Cicada Hyalessa fuscata

Animals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2785
Author(s):  
Hoa Quynh Nguyen ◽  
Yuseob Kim ◽  
Yikweon Jang
Keyword(s):  
Gene Expression ◽  
Heat Stress ◽  
Heat Shock ◽  
Thermal Tolerance ◽  
De Novo ◽  
Expression Patterns ◽  
Thermal Adaptation ◽  
Urban Heat Islands ◽  
Cellular Damage ◽  
Acute Heat Stress

In metropolitan Seoul, populations of the cicada Hyalessa fuscata in hotter urban heat islands (“high UHIs”) exhibit higher thermal tolerance than those in cooler UHIs (“low UHIs”). We hypothesized that heat stress may activate the expression of genes that facilitate greater thermal tolerance in high-UHI cicadas than in those from cooler areas. Differences in the transcriptomes of adult female cicadas from high-UHI, low-UHI, and suburban areas were analyzed at the unheated level, after acute heat stress, and after heat torpor. No noticeable differences in unheated gene expression patterns were observed. After 10 min of acute heat stress, however, low-UHI and suburban cicadas expressed more heat shock protein genes than high-UHI counterparts. More specifically, remarkable changes in the gene expression of cicadas across areas were observed after heat torpor stimulus, as represented by a large number of up- and downregulated genes in the heat torpor groups compared with the 10 min acute heat stress and control groups. High-UHI cicadas expressed the most differentially expressed genes, followed by the low-UHI and suburban cicadas. There was a notable increase in the expression of heat shock, metabolism, and detoxification genes; meanwhile, immune-related, signal transduction, and protein turnover genes were downregulated in high-UHI cicadas versus the other cicada groups. These results suggested that under heat stress, cicadas inhabiting high-UHIs could rapidly express genes related to heat shock, energy metabolism, and detoxification to protect cells from stress-induced damage and to increase their thermal tolerance toward heat stress. The downregulation of apoptosis mechanisms in high-UHI cicadas suggested that there was less cellular damage, which likely contributed to their high tolerance of heat stress.

Insights into the heat-responsive transcriptional network of tomato contrasting genotypes

2021 ◽  
Vol 19 (1) ◽  
pp. 44-57
Author(s):  
Sirine Werghi ◽  
Charfeddine Gharsallah ◽  
Nishi Kant Bhardwaj ◽  
Hatem Fakhfakh ◽  
Faten Gorsane
Keyword(s):  
Heat Stress ◽  
Heat Shock ◽  
Candidate Genes ◽  
Expression Patterns ◽  
Response Strategies ◽  
Transcriptional Reprogramming ◽  
Genes Encoding ◽  
Breeding Programmes ◽  
Gene Transcripts ◽  
Resource Data

AbstractDuring recent decades, global warming has intensified, altering crop growth, development and survival. To overcome changes in their environment, plants undergo transcriptional reprogramming to activate stress response strategies/pathways. To evaluate the genetic bases of the response to heat stress, Conserved DNA-derived Polymorphism (CDDP) markers were applied across tomato genome of eight cultivars. Despite scattered genotypes, cluster analysis allowed two neighbouring panels to be discriminate. Tomato CDDP-genotypic and visual phenotypic assortment permitted the selection of two contrasting heat-tolerant and heat-sensitive cultivars. Further analysis explored differential expression in transcript levels of genes, encoding heat shock transcription factors (HSFs, HsfA1, HsfA2, HsfB1), members of the heat shock protein (HSP) family (HSP101, HSP17, HSP90) and ascorbate peroxidase (APX) enzymes (APX1, APX2). Based on discriminating CDDP-markers, a protein functional network was built allowing prediction of candidate genes and their regulating miRNA. Expression patterns analysis revealed that miR156d and miR397 were heat-responsive showing a typical inverse relation with the abundance of their target gene transcripts. Heat stress is inducing a set of candidate genes, whose expression seems to be modulated through a complex regulatory network. Integrating genetic resource data is required for identifying valuable tomato genotypes that can be considered in marker-assisted breeding programmes to improve tomato heat tolerance.

scholarly journals Ovarian Development and Vitellogenin Gene Expression under Heat Stress in Silkworm,Bombyx mori

2016 ◽  
Vol 2016 ◽  
pp. 1-8
Author(s):  
Satinath Paul ◽  
Bela Keshan
Keyword(s):  
Gene Expression ◽  
Heat Stress ◽  
Heat Shock ◽  
Reproductive Performance ◽  
Ovarian Development ◽  
Fat Body ◽  
Shock Treatment ◽  
Heat Shock Treatment ◽  
Vitellogenin Gene ◽  
Vitellogenin Mrna

The present study observed the effect of heat stress on ovarian development, fecundity, and vitellogenin gene expression in silkworm,Bombyx mori. The result showed that the heat shock treatment to spinning larvae and pupae at 39°C (1 h and 2 h) did not cause any adverse effect on the reproductive performance ofB. mori.However, the heat shock treatment at 42°C or above caused a decrease in the fecundity. The heat shock treatment to day 2 pupae for 2 h at 45°C caused a drastic effect on the development of ovary as measured by gonadosomatic index. The study thus showed that a brief exposure ofBombyxlarvae and pupae to a temperature of 42°C or higher, much prevalent in tropical countries like India, greatly affects the ovarian development and reproductive performance of this commercially important insect. The study further showed a developmental- and tissue-specific expression of vitellogenin mRNA in fat body and ovary upon heat shock. When heat shock treatment was done at 39°C and 42°C to spinning larvae, ovary showed an upregulation in the expression of vitellogenin mRNA, whereas fat body failed to do so. However, at 45°C, both fat body and ovary showed a downregulation. The heat shock treatment to day 2 pupae showed an upregulation in the vitellogenin mRNA expression in both fat body and ovary, even at 45°C. The upregulation in the expression of vitellogenin upon heat shock indicates its role in thermal protection ofBombyxlarvae and pupae.

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