Evolution of thermotolerance and the heat-shock response: evidence from inter/intraspecific comparison and interspecific hybridization in the virilis species group of Drosophila. I. Thermal phenotype

Abstract

SUMMARY Species in the virilis group of Drosophila (fruit flies),which overlap or replace one another along climatic gradients, exhibit corresponding differences in basal thermotolerance, inducible thermotolerance and the heat-shock response. The low-latitude species D. virilisexceeds the high-latitude species D. lummei in these measures of thermotolerance, the temperature threshold for heat-shock factor (HSF)activation and the ability to express hsp70 mRNA and diverse heat-shock proteins (e.g. Hsp70, Hsp83 and small Hsps) after intense heat shock (e.g. 40–41°C). The xeric species D. novamexicanadiffers from the mesic species D. texana in much the same way for many of these traits. By contrast, intraspecific variation in these traits is small. Because D. virilis and D. lummei can readily be crossed to yield partially fertile progeny, genetic analysis of interspecific differences is possible. Interspecific hybrids are intermediate to the parental species in basal thermotolerance and inducible thermotolerance and resemble D. virilis in Hsp concentrations after intense heat shock and Hsp70 protein electromorphs.

Heat shock protein expression enhances heat tolerance of reptile embryos

“…The T on and T max of heat shock response, which are tightly correlated with organismal thermotolerance, are largely determined by heat shock gene expression and differ significantly among species inhabiting thermally distinct environments (e.g. tropical versus arctic zones, terrestrial versus aquatic) [5,[39][40][41][42][43]. Bird eggs are normally brooded by parents, but are sometimes directly exposed to solar radiation (hence extreme high temperature) when brooding parents leave for foraging [22].…”

<I>Mamestra brassicae</I> Nucleopolyhedrovirus Infection and Enhancing Effect of Proteins Derived From <I>Xestia c-nigrum granulovirus</I> in Larvae of <I>Mamestra brassicae</I> and <I>Helicoverpa armigera</I> (Lepidoptera: Noctuidae) on Cabbage

“…The onset temperature at which HSP70 gene expression is upregulated, whether low or high, varies among organisms (Garbuz et al 2003). Tomanek & Somero (1999) suggested that the threshold temperature may be a useful way to identify temperature tolerance limits and that a higher onset temperature is associated with high heat tolerance, and vice versa.…”

Use of surface-enhanced laser desorption ionization–time-of-flight to identify heat shock protein 70 isoforms in closely related species of the virilis group of Drosophila

“…Molecular studies of Hsps in eukaryotic organisms indicate a high degree of conservation during evolution, especially for the best studied 70-kDa protein family (Lindquist and Craig 1988;Hightower 1991;Sorensen et al 2003). This family plays an important role in protein chaperoning and acquired thermotolerance (Garbuz et al 2002(Garbuz et al , 2003Feder and Hofman 1999). Two distinct inducible molecular chaperones of the Hsp70 family occur in various Drosophila species.…”

“…Most molecular and genetic investigations of the Hsp70 family focus on the Hsp70 locus; few address the role of Hsp68 in stress resistance and heat hardening (McColl et al 1996). Our previous investigations reported variation in thermotolerance and the heat shock response in the species of the virilis group of Drosophila (Garbuz et al 2002(Garbuz et al , 2003. The virilis group comprises 12 species living in greatly differing habitats (Patterson and Stone 1952;Throckmorton 1982;Spicer 1992).…”

“…Arrows show the position of unidentified members of Hsp70 family with molecular masses indicated. Two-dimensional gel electrophoresis and other procedures applied were as described (O'Farrell et al 1977;Ulmasov et al 1992;Zatsepina et al 2001;Garbuz et al 2003). The position of major Hsps was determined by both immunoblotting and staining of gels with silver or Coomassie G-250 (Creighton 1990).…”