Larvae of related Diptera species from thermally contrasting habitats exhibit continuous up‐regulation of heat shock proteins and high thermotolerance

Abstract

A population of Stratiomys japonica, a species belonging to the family Stratiomyidae (Diptera), common name 'soldier flies', occurs in a hot volcanic spring, which is apparently among the most inhospitable environments for animals because of chemical and thermal conditions. Larvae of this species, which naturally often experience temperatures more than 40 degrees C, have constitutively high concentrations of the normally inducible heat-shock protein Hsp70, but very low level of corresponding mRNA. Larvae of three other species of the same family, Stratiomys singularior, Nemotelus bipunctatus and Oxycera pardalina, are confined to different type semi-aquatic habitats with contrasting thermal regime. However, all of them shared the same pattern of Hsp70 expression. Interestingly, heat-shock treatment of S. japonica larvae activates heat-shock factor and significantly induces Hsp70 synthesis, whereas larvae of O. pardalina, a species from constant cold environment, produce significantly less Hsp70 in response to heat shock. Adults of the four species also exhibit lower, but detectable levels of Hsp70 without heat shock. Larvae of all species studied have very high tolerance to temperature stress in comparison with other Diptera species investigated, probably representing an inherent adaptive feature of all Stratiomyidae enabling successful colonization of highly variable and extreme habitats.

Thermotolerance and heat shock response in the cold-stenothermal chironomid (NE Italy)

“…Conversely, the pre-exposition treatment emphasized a positive effect on survival to high temperatures (increase of 2°C of LT 100 ). Such a positive effect has not previously been reported for other aquatic cold-stenothermal insects (Rinehart et al 2006;Garbuz et al 2008).…”

“…Similarly to what observed for Oxycera pardalina (Garbuz et al 2008) and B. antarctica (Rinehart et al 2006), also Pseudodiamesa branickii can survive short-term heat shocks at substantially higher temperatures than those they normally face in nature, with a lethal temperature 50% of about 32°C and a lethal temperature 100% of 36°C. However, our experiments of long-term heat shock highlighted that this great ability to survive high temperatures is limited to a very short period of exposure (L Time100 =35 h at 26°C and 7 h at 32°C).…”

“…Data were published on Oxycera pardalina Meigen, 1822 (Diptera, Stratiomidae) from cold springs from Russia (Garbuz et al 2008) and on Belgica antarctica Jacobs, 1900 (Diptera, Chironomidae) from the Antarctic region (Rinehart et al 2006). Garbuz et al (2008) reported a large difference between the lethal temperatures (LT 50 =41.2°C and LT 99 = 43°C) and the natural environmental temperatures (<10°C) of the larvae of Oxycera pardalina. Rinehart et al (2006) observed that the larvae of B. antarctica are strongly thermotolerant with 60% survival after 3 h at 30°C.…”

Cloning of the heat shock protein 90 and 70 genes from the beet armyworm, Spodoptera exigua, and expression characteristics in relation to thermal stress and development

“…Although Se-hsp70 RNA decreased as development progressed, showing the higher expression occurs at young larvae, SeHsp70 proteins at this stage are hardly detectable. This conflict between heat shock RNAs and Hsps usually exist in other species (Garbuz et al 2008). Interestingly, Western blot results showed that the inducible Se-Hsp70 protein is stably present at higher level in pupae in the absence of thermal stress, also, adults of the species exhibits visible amounts of Se-Hsp70 protein at normal temperature, thus eliciting a significant importance of the regulation mechanism underlying transcription and translation for these HSPs during development in insects.…”

Proteome stability, heat hardening, and heat-shock protein expression profiles in Cataglyphis desert ants

“…High constitutive expression of molecular chaperones has been reported in a number of ectotherms living under stressful conditions (e.g. elevated temperature, high salinity), including molluscs (Dong et al, 2008), echinoderms (González et al, 2016), dipterans (Rinehart et al, 2006;Garbuz et al, 2008) and lizards (Zatsepina et al, 2000). The sustained production of HSC70 by C. bombycina and C. mauritanica is probably an adaptation for coping with heat.…”