Animals at the extremes: the desert environment
Animals at the extremes: the desert environment

Start this free course now. Just create an account and sign in. Enrol and complete the course for a free statement of participation or digital badge if available.

4.1.1 Summary of Section 4

The integration of physiological and molecular responses links an environmental signal to a physiological response. Heat-shock proteins (Hsps) are chaperone proteins that maintain the structure and function of proteins in cells exposed to high temperatures. The initial response of cells to high temperatures is rapid transcription of heat-shock genes, e.g. Hsp70, which is possible because Hsp70 is normally partly transcribed by RNA polymerase II. Resumption of transcription requires only three steps: release, then trimerisation of HSTF (heat-shock transcription factor), followed by binding to HSEs (heat-shock regulatory elements) in the promoters.

At T a 25°C, the desert reptiles Phrynocephalus interscapularis and Crossobamon eversmanni have high constitutive levels of Hsps in their cells, in contrast to a temperate species, Lacerta vivipara. Cells from P. interscapularis and Gymnodactylus caspius kept at 25°C contained high levels of active HSTF bound to HSE in contrast to cells from L. vivipara, suggesting that in desert species HSTF genes are expressed constitutively. Protein synthesis in liver cells of desert species continued normally following heat shock up to 45°C, whereas in L. vivipara protein synthesis in the liver plummeted after heat shock at 37°C. Cells of desert species are well prepared for heat shock.

Take your learning further

Making the decision to study can be a big step, which is why you'll want a trusted University. The Open University has 50 years’ experience delivering flexible learning and 170,000 students are studying with us right now. Take a look at all Open University courses.

If you are new to University-level study, we offer two introductory routes to our qualifications. You could either choose to start with an Access module, or a module which allows you to count your previous learning towards an Open University qualification. Read our guide on Where to take your learning next for more information.

Not ready for formal University study? Then browse over 1000 free courses on OpenLearn and sign up to our newsletter to hear about new free courses as they are released.

Every year, thousands of students decide to study with The Open University. With over 120 qualifications, we’ve got the right course for you.

Request an Open University prospectus371