By way of comparison, then, our failure to detect any enrichment of AGO1 or transcripts under miRNA control in sponge TH-302 918633-87-1 bodies indicates that the fraction present must be substantially less than the 2% of the cited example; in effect, there can be essentially no enrichment at all. The distribution of miRNPs within the cell is relevant to the mechanism by which translation is repressed by miRNAs. P bodies lack ribosomes, and the presence of certain miRNPs and their regulated mRNAs within P bodies indicates that these mRNAs are not undergoing translation. There is also evidence for regulation by miRNAs after initiation of translation, with the repressed mRNAs being associated with polysomes. Obviously, such a mechanism could not apply for the mRNAs found in P bodies. Consequently, any enrichment of miRNPs in sponge bodies , would be consistent with repression blocking initiation of translation. The observed absence of such an enrichment raises the possibility that whatever mechanism delivers miRNPs to the P bodies is not operating in the germline cells of the ovary , at least for the developmental stages examined. While this does not rule out miRNA-dependent translational repression at the level of initiation, it does leave open the possibility that action of miRNAs after initiation of translation may be more prominent in this setting than in cells with conventional P bodies. Since temperate bacteriophages are known to transfer antibiotic resistance and virulence genes from one bacterium to another, a process known as lysogenic conversion, the absence of temperate bacteriophages from the host bacteria used in the production of BFC-1 had to be confirmed. Several tools have been developed to customize the analysis of gene expression data. Novel mapping of given probe sequences to more recent genomic data was performed by Gautier et al. and Harbig et al.. Both groups were able to show that remapping of the probe sequences affects data analysis for specific arrays. Dai et al. introduced re-defined probe sets after realignments of probe sequences to genes as well as transcripts. However, as probes of a given probe set were allowed to match several different transcripts, their overall signal will still be influenced by several transcripts. Additional alignment algorithms were used to define transcript-specific probe sets employing different databases as RefSeq or AceView. However, none of these reports experimentally validated alternative transcript expression. Evidence of neurogenesis in the adult brain of birds , rodents and primates, and the demonstration of the presence of stem cells in specific brain regions, such as the subventricular zone and the hippocampus , brought new perspectives for cell therapy and neural regeneration. During development of the central nervous system , there is extensive proliferation of neuroepithelial cells lining the ventricular walls which give rise to the neurons, astrocytes and oligodendrocytes of the mature brain.