Ancient heat shock gene is dispensable.

Hsp83 is a major eucaryotic heat shock protein and one of the most conserved proteins known. We have isolated an Escherichia coli gene homologous to eucaryotic Hsp83 and used it to construct a deletion mutation. The E. coli mutant was viable but had a slight growth disadvantage that increased with temperature.     

Differential heat shock gene expression in chick blastula

Summary The component areas of chick blastula show differential expression of heat shock genes. The area opaca (ao), marginal zone (mz) and central area (ca) components of the epiblast display distinct quantitative and minor qualitative differences in the heat-induced and heat-repressible proteins, but are clearly different from the primary hypoblast (endoderm) in their expression of a given stress protein (hsp) as a response to heat shock. The major proteins synthesized in the component areas of epiblast in response to heat shock include hsp 18, 24, 70 and 89 Kd. Two-dimensional electrophoresis shows that each of these proteins consists of multiple charged species. The hypoblast expresses only hsp 70 Kd at non-significant levels and shows marked inhibition in the level of synthesis of heat-shock-repressible proteins. Heat shock during the blastula stage results in an increase in the size of the blastoderm and disrupts normal embryonic development. The heat shock genes provide an important molecular marker, which attests to regional specification in the chick blastula.     

Expression of the heat shock gene clpL of Streptococcus thermophilus is induced by both heat and cold shock

Background  

Heat and cold shock response are normally considered as independent phenomena. A small amount of evidence suggests instead that interactions may exist between them in two Lactococcus strains.     

Acclimation,heat shock and hardening

The purpose of this commentary is to open a debate on the usage of the terms acclimation, heat shock and hardening within the thermal biology literature. The terms all refer to a particular treatment modality, the responses of ectotherms to which are diverse, but are linked by the common outcome of changing their resistance to exposure to high lethal temperatures. In my view the common outcome of these treatments has resulted in these terms being used in divers ways, with a resultant lack of clarity in both the purpose and interpretation of the associated published work.     

Identification and expression of a cloned yeast heat shock gene

We have isolated the yeast HSP90 gene which encodes the Mr = 90,000 heat shock-inducible protein of this organism. When this gene is introduced into yeast on a multicopy plasmid vector, a dramatic increase is observed in the level of synthesis of the Mr = 90,000 heat shock-inducible protein. This protein overproduction is due to expression of the plasmid-borne HSP90 gene, which is under the same heat shock regulation as its chromosomal counterpart. The presence of an increased dosage of the HSP90 gene has no effect on the synthesis of the other major heat shock-inducible proteins and does not alter the heat shock-associated phenotype of thermal tolerance.     

Overexpression of heat shock protein gene PfHSP21.4 in Arabidopsis thaliana enhances heat tolerance

Nuclear-encoded chloroplast small heat shock proteins (Cp-sHSPs) play important roles in plant stress tolerance due to their abundance and diversity. Their functions in Primula under heat treatment are poorly characterized. Here, expression analysis showed that the Primula Cp-sHSP gene, PfHSP21.4, was highly induced by heat stress in all vegetative and generative tissues in addition to constitutive expression in certain development stages. PfHSP21.4 was introduced into Arabidopsis, and its function was analysed in transgenic plants. Under heat stress, the PfHSP21.4 transgenic plants showed increased heat tolerance as shown by preservation of hypocotyl elongation, membrane integrity, chlorophyll content and photosystem II activity (Fv/Fm), increased seedling survival and increase in proline content. Alleviation of oxidative damage was associated with increased activity of superoxide dismutase and peroxidase. In addition, the induced expression of HSP101, HSP70, ascorbate peroxidase and Δ1-pyrroline-5-carboxylate synthase under heat stress was more pronounced in transgenic plants than in wild-type plants. These results support the positive role of PfHSP21.4 in response to heat stress in plants.     

Expression of the small heat shock protein gene, hsp30, in Rana catesbeiana fibroblasts

In the present study, we examined the expression of the Rana catesbeiana small heat shock protein gene, hsp30, in an FT fibroblast cell line. Northern and western blot analyses revealed that hsp30 mRNA or HSP30 protein was not present constitutively but was strongly induced at a heat shock temperature of 35 degrees C. However, treatment of FT cells with sodium arsenite at concentrations that induced hsp gene expression in other amphibian systems caused cell death. Non-lethal concentrations of sodium arsenite (10 microM) induced only minimal accumulation of hsp30 mRNA or protein after 12 h. Immunocytochemical analyses employing laser scanning confocal microscopy detected the presence of heat-inducible HSP30, in a granular or punctate pattern. HSP30 was enriched in the nucleus with more diffuse localization in the cytoplasm. The nuclear localization of HSP30 was more prominent with continuous heat shock. These heat treatments did not alter FT cell shape or disrupt actin cytoskeletal organization. Also, HSP30 did not co-localize with the actin cytoskeleton.