Expression of heat shock protein genes Aaehsp26, Aaehsp83 and Aaehsc70 in response to thermal stress in Aedes aegypti larvae

Climate change is responsible to a certain extent for the occurrence and spread of arboviral pathogens worldwide. Temperature is one of the crucial abiotic factors influencing the physiological processes of mosquitoes. Several genes of heat shock protein (AaeHsp26, AaeHsp83, and AaeHsc70) families are known to be expressed in mosquitoes, which aid in overcoming stress induced by elevated temperature. In this study, the relative expression of heat shock protein genes has been examined using Quantitative Real-time PCR (qPCR). The temperatures used for heat shock treatment were 27(control), 37, and 42°C for 1 hour heat shock period and applied to 3rd instar larvae. Significant up-regulation has been seen at 37, and 42°C. The highest expression level, about 82.43 fold, was reported for the AaeHsc70 gene at 42°C followed by 78.36 fold for AaeHsp26 at 37°C and 4.79 fold for AaeHsp83 at 42°C. The current study has shown that HSPs are important markers of stress and may function as critical proteins to protect and enhance the survival of Ae. aegypti larvae and pupae. Biological implications of these findings could impact the vector competencies Dhaka Univ. J. Biol. Sci. 30(2): 233-241, 2021 (July)

Heat-induced triploids in Brycon amazonicus: a strategic fish species for aquaculture and conservation

Summary Triploidization plays an important role in aquaculture and surrogate technologies. In this study, we induced triploidy in the matrinxã fish (Brycon amazonicus) using a heat-shock technique. Embryos at 2 min post fertilization (mpf) were heat shocked at 38°C, 40°C, or 42°C for 2 min. Untreated, intact embryos were used as a control. Survival rates during early development were monitored and ploidy status was confirmed using flow cytometry and nuclear diameter analysis of erythrocytes. The hatching rate reduced with heat-shock treatment, and heat-shock treatments at 42°C resulted in no hatching events. Optimal results were obtained at 40°C with 95% of larvae exhibiting triploidy. Therefore, we report that heat-shock treatments of embryos (2 mpf) at 40°C for 2 min is an effective way to induce triploid individuals in B. amazonicus.

Improved strategies to efficiently isolate thermophilic, thermotolerant, and heat-resistant fungi from compost and soil

Thermophilic, thermotolerant and heat-resistant fungi developed different physiological traits, enabling them to sustain or even flourish under elevated temperatures, which are life-hostile for most other eukaryotes. With the growing demand of heat-stable molecules in biotechnology and industry, the awareness of heat-adapted fungi as a promising source of respective enzymes and biomolecules is still increasing. The aim of this study was to test two different strategies for the efficient isolation and identification of distinctly heat-adapted fungi from easily accessible substrates and locations. Eight compost piles and ten soil sites were sampled in combination with different culture-dependent approaches to describe suitable strategies for the isolation and selection of thermophilous fungi. Additionally, an approach with a heat-shock treatment, but without elevated temperature incubation led to the isolation of heat-resistant mesophilic species. The cultures were identified based on morphology, DNA barcodes, and microsatellite fingerprinting. In total, 191 obtained isolates were assigned to 31 fungal species, from which half are truly thermophilic or thermotolerant, while the other half are heat-resistant fungi. A numerous amount of heat-adapted fungi was isolated from both compost and soil samples, indicating the suitability of the used approaches and that the richness and availability of those organisms in such environments are substantially high.

Induction of tocopherol biosynthesis through heat shock treatment in Arabidopsis

ABSTRACT Plants have developed various self-defense systems to survive many types of unfavorable conditions. Heat shock (HS) treatment, an abiotic stress, activates salicylic acid (SA) biosynthesis to enhance resistance to biotic stresses in some plant species. Since SA is produced from the shikimate pathway, other related metabolic pathways were expected to be upregulated by HS treatment. We speculated that tocopherol biosynthesis utilizing chorismic acid would be activated by HS treatment. In Arabidopsis, expression analysis of tocopherol biosynthetic genes, HPPD, VTE2, VTE3, VTE1, and VTE4, in combination with measurement of metabolites, indicated that HS treatment enhanced the biosynthesis and accumulation of tocopherols. Analyses using an SA biosynthesis-deficient mutant indicated that the upregulation of tocopherol biosynthesis was independent of the SA-mediated signaling pathway.

Protective effect of Zingiber zerumbet Smith extract on thermotolerance

Background: Global warming causes severe heat conditions. Heat stress contributes to higher morbidity of heatstroke in human and mortality in livestock. To protect them from heat stress, thermotolerance mechanisms were widely studied, and some studies suggest relationship between heat shock proteins (HSPs) and thermotolerance. HSPs were not induced by only heat shock but also some stimulations including bioactive compounds from plants. Zingiber zerumbet is a perennial herb found in many tropical countries, including Thailand. The rhizome of Zingiber zerumbet contains zerumbone that is a bioactive compound to induce HSPs expression in animal cells.Objective: To prevent higher morbidity of heatstroke in human and mortality in livestock by the heat stress, we investigated the effect of zerumbone, the extract of Zingiber zerumbet Smith, on thermotolerance, using a cell line and mice.Methods: The murine liver hepatoma cell line, Hepa1c1c7 cells, were incubated in medium supplemented with extract from rhizome of Zingiber zerumbet Simith containing zerumbone, and then the expression of heat shock proteins (HSP) 40, 70 and 90 were investigated by western blotting. Furthermore, we established the evaluation system of thermotolerance using mice, and studied the effect of the extract on the growth rate of mice under the heat shock treatment. Briefly, 4 weeks old C57BL6 mice were fed that with the extract (or vehicle) for a week before the first heat shock treatment (38 °C for an hour). Before and after five days heat treatment, body weights were measured. The protein expressions of heat shock proteins in liver were measured by western blotting using HSPs antibodies.Results: The extract of Zingiber zerumbet rhizome, equivalent to 50 μM zerumbone, significantly increased the expression of heat shock proteins (HSP40, HSP70, HSP90). The growth rate of the mice under the heat treatment were lower than control. The feeding with the extract containing 25 ppm zerumbone have significantly attenuated the decline of the growth rate led by the heat treatment, whereas there was little effect on mouse growth rate grown under normal conditions. The protein expression of HSP70 in the liver of zerumbone-fed mice was upregulated compared with control mice, equivalent to heat treatment without zerumbone. On the other hand, both treatments of zerumbone and heat resulted in highest HSP70 expression among four groups.Conclusion: Our study demonstrated that oral administration of the extract of Zingiber zerumbet Smith led to the attenuation of decline of growth rate induced by heat treatment. HSP70 expression in murine liver was enhanced by either feeding the extract or heat treatment. More interestingly, HSP70 expression was further enhanced by both treatments of zerumbone and heat. These results suggested that zerumbone may contribute to thermotolerance via, at least, HSP70 expression.Keywords: Zingiber zerumbet, thermotolerance, heat shock protein

Dynamics of Whole-Genome Contacts of Nucleoli in Drosophila Cells Suggests a Role for rDNA Genes in Global Epigenetic Regulation

Chromosomes are organized into 3D structures that are important for the regulation of gene expression and differentiation. Important role in formation of inter-chromosome contacts play rDNA clusters that make up nucleoli. In the course of differentiation, heterochromatization of rDNA units in mouse cells is coupled with the repression or activation of different genes. Furthermore, the nucleoli of human cells shape the direct contacts with genes that are involved in differentiation and cancer. Here, we identified and categorized the genes located in the regions where rDNA clusters make frequent contacts. Using a 4C approach, we demonstrate that in Drosophila S2 cells, rDNA clusters form contacts with genes that are involved in chromosome organization and differentiation. Heat shock treatment induces changes in the contacts between nucleoli and hundreds of genes controlling morphogenesis. We show that nucleoli form contacts with regions that are enriched with active or repressive histone marks and where small non-coding RNAs are mapped. These data indicate that rDNA contacts are involved in the repression and activation of gene expression and that rDNA clusters orchestrate large groups of Drosophila genes involved in differentiation.

Transcriptome analysis in osmo-primed tomato seeds with enhanced longevity by heat shock treatment

Seed priming is widely used in commercial seeds and its main function is to accelerate and synchronize seed germination. Undesirably, primed seeds show reduced longevity and treatments like heat shock have been shown to improve longevity in primed seeds. Nonetheless, the effect of heat shock treatment on primed seeds at the mRNA level is not known. Thus, the aim of this work was to investigate the effect of heat shock treatment on the longevity of primed tomato (Solanum lycopersicum) seeds at the physiological and transcriptome levels. Tomato seeds were primed and dried (control). Alternatively, primed seeds were subjected to heat shock treatment (38 °C/32 % relative humidity) before drying. Germination, vigor and longevity were evaluated. Transcriptome analysis was performed by RNA sequencing (RNA-seq) from biological samples collected immediately after priming and another samples collected from primed seeds followed by the heat shock treatments. The gene expression was validated by quantitative real time PCR (RT-qPCR). We showed that applying heat shock treatment after priming increased germination speed, enhanced seed longevity and preserved the vigor during storage of primed tomato seeds. Through transcriptome analysis, 368 differentially expressed genes were identified, from which 298 genes were up-regulated and 70 were down-regulated. We showed the increase of mRNA levels of HEAT SHOCK FACTOR-like and HEAT SHOCK PROTEIN-like chaperone genes, suggesting the involvement of the proteins coded by these transcripts in the enhancement of longevity in primed tomato seeds. The heat shock treatment after priming enhances and preserves the vigor of tomato primed seeds during storage. In addition, improves seed longevity through the increase in the expression of transcripts related to protection by response to stress.