Lessons to learn from the cell death and heat shock genes of Caenorhabditis elegans

The biology of the post-genomic era: the proteomics

The complete identification of coding sequences in a number of species has led to announce the beginning of the post-genomic era, new tools have become available to study complex phenomena in biological systems. Rapid advances in genomic sequencing and bioinformatics have established the field of genomics to investigate thousands genes' activity through mRNA display. However, recent studies have demonstrated a lack of correlation between the transcriptional profiles and the actual protein levels in cells, so investigation of the expressed part of the genome is also required to link genomic data to biological function. It is possible that evolutional development occured by increasing complexity of regulation processes at the level of RNA and protein molecules instead of simple increase in gene number, so investigation of proteins and protein complexes became important fields of our post-genomic era. High-resolution two-dimensional gels combined with sensitive mass spectrometry can reveal virtually all proteins present in cells opening new insights into functions of cells, tissues and whole organisms.

Developmental upregulation of inducible hsp70 transcripts, but not the cognate form, during pupal diapause in the flesh fly, Ssarcophaga crassipalpis

Partial clones of the Sarcophaga crassipalpis heat shock protein 70 (hsp70) and of heat shock cognate 70 (hsc70) were developed by RT-PCR and library screening respectively. These clones were used to probe total RNA northern blots for the expression of transcripts in response to high and low temperature stress and in conjunction with the entry into an overwintering pupal diapause. In nondiapausing individuals, hsp70 was highly expressed in response to a 40 degrees C heat shock, while hsc70 was unaffected by the heat stress. In contrast, both hsp70 and hsc70 were upregulated in nondiapausing flies following a -10 degrees C cold shock. In diapausing pupae, hsp70 was highly upregulated during diapause, even at a non-stress temperature of 20 degrees C. Upregulation was initiated at the onset of diapause and persisted throughout diapause. During diapause, heat shock did not further elevate the level of hsp70 expression. Within 12 h after diapause was terminated, hsp70 ceased to be expressed. The expression of hsc70 was unaltered by diapause. The developmental regulation of hsp70 in relation to diapause suggests a critical role for this stress protein during insect dormancy.