• Mycobiology
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• v.42 no.1
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• pp.59-65
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• 2014

Entomopathogenic fungi are promising pest-control agents but their industrial applicability is limited by their thermosusceptibility. With an aim to increase the thermotolerance of Isaria fumosorosea SFP-198, moisture absorbents were added to dried conidial powder, and the relationship between its water potential and thermotolerance was investigated. Mycotized rice grains were dried at $10^{\circ}C$, $20^{\circ}C$, $30^{\circ}C$, and $40^{\circ}C$ and the drying effect of each temperature for 24, 48, 96, and 140 hr was determined. Drying for 48 hr at $10^{\circ}C$ and $20^{\circ}C$ reduced the moisture content to < 5% without any significant loss of conidial thermotolerance, but drying at $30^{\circ}C$ and $40^{\circ}C$ reduced both moisture content and conidial thermotolerance. To maintain thermotolerance during storage, moisture absorbents, such as calcium chloride, silica gel, magnesium sulfate, white carbon, and sodium sulfate were individually added to previously dried-conidial powder at 10% (w/w). These mixtures was then stored at room temperature for 30 days and subjected to $50^{\circ}C$ for 2 hr. The white carbon mixture had the highest conidial thermotolerance, followed by silica gel, magnesium sulfate, and then the other absorbents. A significant correlation between the water potential and conidial thermotolerance was observed in all conidia-absorbent mixtures tested in this study (r = -0.945). Conidial thermotolerance in wet conditions was evaluated by adding moisturized white carbon (0~20% $H_2O$) to conidia to mimic wet conditions. Notably, the conidia still maintained their thermotolerance under these conditions. Thus, it is evident that conidial thermotolerance can be maintained by drying mycotized rice grains at low temperatures and adding a moisture absorbent, such as white carbon.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2002.05b
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• pp.471-474
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• 2002

SA treatment significantly increased thermotolerance In cucumber seedlings. Pretreatment of seeds with $CaCl_2$ solution enhanced the SA- induced thermotolerance. On the contrary, pretreatment with the $Ca^{2+}$ chelator EGTA lowered this SA-induced thermotolerance. In addition, pretreatment with $Ca^{2+}$ channel blocker verapamil also weakened the SA-induced thermotolerance. However, the calmodulin antagonist chlorpromazine(CPZ) had little effect on the SA-induced thermotolerance. Measurement of activity of the antioxidant enzyme APX and the level of lipid peroxidation (in term of MDA) indicated that heat stress induced an oxidative stress in cucumber seedlings. SA treatment induced higher activities of APX and a lower level of lipid peroxidation. $Ca^{2+}$ pretreatment further enhanced the SA-induced increase in APX activity and lowered the heat stress-induced lipid peroxidation, but EGTA pretreatment had a contrary effect. These results suggest that $Ca^{2+}$ and calmodulin may be involved In the acquisition of the SA-induced thermotolerance; antioxidant enzyme system take part in the final generation of the SA-induced thermotolerance.

• Journal of Microbiology and Biotechnology
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• v.13 no.1
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• pp.85-89
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• 2003

The difference in the thermotolerance between Saccharomyces cerevisiae KNU5377 and ATCC24858 was compared by assaying the amounts of trehalose accumulated under growth and heat shock conditions. Both strains exhibited similar trehalose accumulation during the growth period, but an intrinsic thermotolerance was much higher in KNU5377 than in the control strain. This result implied that some strain-specific characteristics of KNU5377, other than trehalose accumulation, primarily were responsible fur its higher intrinsic thermotolerance. Heat shock at $43^{\circ}C$ for 90 min to the exponentially growing cells resulted in the maximum level of trehalose In both strains. Trehalose accumulated at least twice more in KNU5377 by the heat shock than in the control, due to the maintenance of its neutral trehalase activity even after the heat shock. Consequently, the Increase of acquired thermotolerance in both strains correlated with an increase in the trehalose content in each strain. In conclusion, KNU5377 exhibited a well-modulated trehalose-related mechanism to accumulate more trehalose by means of maintaining neutral trehalase activity after heat shock than the control strain, thereby contributing to its acquired thermotolerance.

• Journal of Microbiology and Biotechnology
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• v.22 no.1
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• pp.118-125
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• 2012

Heat shock proteins (Hsps) play a key role in the cellular defense response to diverse environmental stresses. Here, the role of Hsp genes in the acquisition of thermotolerance in the cyanobacterium Microcystis aeruginosa NIES-298 was investigated. Twelve Hsp-related genes were examined to observe their modulated expression patterns at different temperatures (10, 15, 25, and $35^{\circ}C$) over different exposure periods. HspA and HtpG transcripts showed an up-regulation of expression at low temperatures (10 and $15^{\circ}C$) and high temperature ($35^{\circ}C$), compared with the control ($25^{\circ}C$). To examine their effects upon thermotolerance, we purified recombinant HspA and HtpG proteins. During a thermotolerance study at $54^{\circ}C$, the HspA-transformed bacteria showed increased thermotolerance compared with the control. HtpG also played a role in the defense response to acute heat stress within 30 min. These findings provide a better understanding of cellular protection mechanisms against heat stress in cyanobacteria.

• Journal of Microbiology and Biotechnology
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• v.20 no.9
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• pp.1348-1350
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• 2010

Conidia of Beauveria bassiana ARSEF-7060, produced in millet amended with plant oils such as sunflower, corn, or cotton seed oil, were exposed to $45^{\circ}C$ of wet heat for 90 min. Conidia from millet+corn oil medium had the highest thermotolerance [$LT_{50}$ (median survival time): 45.7 min]. The mycotized millet grains were coated with each of the same plant oils as a granular formulation and subjected to $50^{\circ}C$ of dry heat for 8 h. Corn oil coating ($LT_{50}$: 8.68 h) was superior to sunflower and cotton seed oil coatings, suggesting the feasibility of using corn oil to increase conidial thermotolerance.

• The Korean Journal of Zoology
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• v.30 no.3
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• pp.301-310
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• 1987

본 실험에서는 반SP와 thermotolerance 사이에 어떠한 상관관계가 있는지를 알아보기 위하여, 생쥐 SCK 종양세포에서 heat(45$^{\circ}$, 46$^{\circ}C$)처리가 단백질 합성과 세포의 생존에 미치는 영향을 비교하여 보았다. 그 결과 heat 처리를 받은 세포는 HS$\ulcorner$(70K, 87K)를 측이하게 많이 합성했으며, 다음 heat를 받았을 때는 높은 생존율을 꼬였다. 그리고 이러한 thermotolerance가 생성되고 감퇴되는 kinetics는 HSP가 합성되고 감퇴되는 kinetics와 연관성을 보여 주었다. 이러한 결과로 HSP는 heat shock로부터 세포를 보호하는 데 중요한 역할을 할 수 있다고 생 각된다. 아울러, glycerol을 처리하여 HSP의 합성을 봉쇄시켰을 경우에도 열에 대해 저항성을 갖게 되는 실험결과로 미루어, 세포가 갖게 되는 heat resistance에는 (1) HSP의 합성을 초래하지 않는 요인에 의해 유도되는 heatprotection과 (2) 열처리 등의 결과 합성되는 반SP에 의해 유도되는 thermotolerance의 두가지 경우가 있을 것으로 추론할 수 있었다.

• Journal of Plant Biotechnology
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• v.3 no.1
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• pp.7-12
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• 2001

An antiserum against the carrot HSP17 (17 KDa heat shock protein) was raised using the HSP17 purified after being expressed in a recombinant E.coli in order to develop an assay system for thermotolerance in crops. The DCHsp17.7 including the coding sequence corresponding to a carrot HSP17 protein was recombined within pET-32(b) vector and achieved a maximum expression in 4 hours after an induction in E.coli. The purified DCHsp17.7 was used as an antigen to generate the corresponding antibody. The polyclonal antiserum was confirmed for it's specificity only to the low molecular weight (1mw) HSP. Besides, the possibilities to use the antiserum to interact with 1mwHSPs from other plants such as rice, cucumber, tomato, and hot pepper were examined to be plausible. To reveal any specific correlation between the amounts of 1mwHSP expressed upon HS conditions and an acquisition of thermotolerance two different approaches have been applied. first, it has been shown that only the pre-HS conditions inducing the synthesis of HSP17 allowed for the seedlings to achieve an thermotolerance and to survive the following lethal condition. Second, a western analysis using 15 different collected lines of hot peppers was performed to distinguish each other in terms of the amount of 1mwHSP. The results indicated that all 14 hot pepper lines were able to synthesize HSPs in response to an exposure to HS conditions and the amounts of the proteins synthesized at different HS temperatures were variable among the lines. There are several different patterns of 1mwHSP synthesized as a function of temperature increase observed and their correlation to physiological aspects of thermotolerance remains to be analyzed.

• Asian-Australasian Journal of Animal Sciences
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• v.18 no.1
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• pp.107-112
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• 2005

A high environmental temperature affects the economic performance of pigs. Heat shock protein 70 (HSP70) has been reported to participate importantly in thermotolerance. This study aims to produce transgenic pigs overexpressing porcine HSP70.2, the highly inducible one of HSP70 members, and to prove the cellular thermotolerance in the primary fibroblasts from the transgenics. A recombinant plasmid in which the sequence that encodes the porcine HSP70.2 gene is fused to green fluorescence protein (GFP) was constructed under the control of cytomegalovirus (CMV) enhancer and promoter. Two transgenic pigs were produced by microinjecting pCMV-HSP70-GFP DNA into the pronucleus of fertilized eggs. Immunoblot assay revealed the varied overexpression level (6.4% and 1.4%) of HSP70-GFP in transgenic pigs. After heating at $45^{\circ}C$ for 3 h, the survival rate (78.1%) of the primary fibroblast cells from the highly expressing transgenic pig exceeded that from the non-transgenic pig (62.9%). This result showed that primary fibroblasts overexpressing HSP70-GFP confer cell thermotolerance. We suggest that transgenic pigs overexpressing HSP70 might improve their thermotolerance in summer and therefore reduce the economic loss in animal production.

• Asian-Australasian Journal of Animal Sciences
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• v.32 no.6
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• pp.842-848
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• 2019

Objective: Heat stress poses an increasing threat for poultry production. Some amino acids have been found to play critical roles in affording thermotolerance. Recently, it was found that in ovo administration of L-leucine (L-Leu) altered amino acid metabolism and afforded thermotolerance in heat-exposed broiler chicks. Methods: In this study, two doses (35 and $70{\mu}mol/egg$) of L-Leu were administered in ovo on embryonic day 7 to determine their effect on rectal temperature (RT), body weight (BW) and thyroid hormones at hatching. Changes in RT, BW, and thermotolerance in post-hatched chicks were also analyzed. Results: It was found that in ovo administration of L-Leu dose-dependently reduced RT and plasma thyroxine ($T_4$) level just after hatching. In post-hatched neonatal broiler chicks, however, the higher dose of L-Leu administered in ovo significantly increased RT without affecting BW gain. In chicks that had been exposed to heat stress, the RT was significantly lowered by in ovo administration of L-Leu (high dose) in comparison with the control chicks under the same high ambient temperature (HT: $35^{\circ}C{\pm}1^{\circ}C$, 120 min). Conclusion: In ovo administration of L-Leu in a high dose contributed to an increased daily body temperature and afforded thermotolerance under HT in neonatal broiler chicks.

• International Journal of Industrial Entomology and Biomaterials
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• v.31 no.2
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• pp.115-126
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• 2015

The tropical climate prevailing in India adversely affects temperate bivoltine silkworm rearing and causes crop loss especially during summer. Identification of high temperature tolerant bivoltine breeds by screening for thermotolerance in the silkworm, Bombyx mori (Lepidoptera: Bombycidae) is an essential prerequisite for the development of thermotolerant bivoltine breeds / hybrids. Therefore, in this study, 20 silkworm breeds were reared at different temperatures (25 ± 1℃,32 ± 1℃, 34 ± 1℃ and 36 ± 1℃) for 6 h every day from 3^rd d of 5^th instar to till spinning. Significant differences (p < 0.01) were found among all the rearing traits over temperature. Based on pupation percentage, SK4C and BHR3 were identified as thermotolerant bivoltine breeds. Hierarchical clustering analysis based on rearing traits at tested temperatures grouped 20 silkworm breeds in four clusters which included one cluster each of susceptible and tolerant, and two clusters of moderately tolerant silkworm breeds. This suggests that clustering based on rearing data at high temperatures by using Euclidean distance can be an effective approach in classifying the silkworm breeds on their thermotolerance capacity. The identified breeds would be used for development of thermo tolerant bivoltine silkworm breeds / hybrids.