For the cold tolerant process of intracellular freezing, very little is as yet known of the mechanisms that allow this to occur, with no molecular work done on any organism to date. However it would be surprising if many of the above mentioned genes were not in some way involved, either mechanistically, or in terms of stress response. From the beginning of the molecular focus on P. davidi, a vital question has been whether it is susceptible to environmental RNA interference. If so, it would provide a method of functionally investigating survival of intracellular freezing. We have provided an in silico search for RNAi specific genes. As with the IAP, an inability to find a key gene does not preclude there being one. However, so far there has been no in silico evidence of sid-2, even though a number of other associated genes are present. As pointed out in the introduction, without sid-2, even if other associated RNAi genes were present, it is considered unlikely that P. davidi would have an environmental response to RNAi. Gene expression is a highly dynamic and efficient process that couples transcription with pre-mRNA processing. The functional union of gene transcription with processing of nascent transcripts occurs in a spatially organized manner in the nucleus. Activation of RNA polymerase II occurs in conjunction with binding of trans-proteins to cis-elements in gene promoters and recruitment of members of the SR protein family of splicing factors. Regulation of transcription occurs through DNA modifications and changes in transcription factor expression, activity, and localization. In addition to these generalized processes, transcription factor expression and GANT61 Hedgehog inhibitor activity is also subjected to tissue-specific mechanisms of regulation. This process enables expression of restricted sets of tissue-specific transcripts. Subsequently, these transcripts are processed by ubiquitously expressed splicing factors to generate alternative transcripts, thereby increasing proteome complexity and ensuring functional diversity. Unlike the well-defined role of trans-acting proteins in regulating tissue-specific gene expression, the generation of cell type- and tissue-specific proteomes has only recently been linked to changes in splicing factor expression and activity. Notwithstanding regulation through changes in expression and activity, few tissue-specific splicing factors have been identified. Most notably, NOVA1 and NOVA2 neuron-specific KH-type RNA binding proteins regulate splicing of transcripts encoding numerous synaptic.