Dicer inactivation leads to progressive functional and structural degeneration of the mouse retina.

MicroRNAs (miRNAs) are small, highly conserved molecules that have been shown to regulate the expression of genes by binding to specific target mRNAs. Dicer, an RNase III endonuclease, is essential for the production and function of mature miRNAs, and removal of Dicer has been shown to disrupt many developmental processes. In this study, Dicer was removed specifically from the retina using a floxed Dicer conditional allele and the retinal Chx10Cre transgene. Retinal Dicer knock-out mice displayed a reproducible inability to respond to light. In addition, morphological defects were observed with the formation of photoreceptor rosettes at postnatal day 16, which progressed to more general cellular disorganization and widespread degeneration of retinal cell types as the animals aged. This was accompanied by concomitant decrease in both scotopic and photopic electroretinogram (ERG) responses. Interestingly, removing a single allele of Dicer resulted in ERG deficits throughout life but not to morphological abnormalities. Northern blot analysis of Dicer-depleted retinas showed a decrease in several miRNAs. The observation that progressive retinal degeneration occurred after removal of Dicer raises the possibility that miRNAs are involved in retinal neurodegenerative disorders.

Members of the miRNA-200 family regulate olfactory neurogenesis.

MicroRNAs (miRNAs) are highly expressed in vertebrate neural tissues, but the contribution of specific miRNAs to the development and function of different neuronal populations is still largely unknown. We report that miRNAs are required for terminal differentiation of olfactory precursors in both mouse and zebrafish but are dispensable for proper function of mature olfactory neurons. The repertoire of miRNAs expressed in olfactory tissues contains over 100 distinct miRNAs. A subset, including the miR-200 family, shows high olfactory enrichment and expression patterns consistent with a role during olfactory neurogenesis. Loss of function of the miR-200 family phenocopies the terminal differentiation defect observed in absence of all miRNA activity in olfactory progenitors. Our data support the notion that vertebrate tissue differentiation is controlled by conserved subsets of organ-specific miRNAs in both mouse and zebrafish and provide insights into control mechanisms underlying olfactory differentiation in vertebrates.

Creating what sort of professional? Master's level nurse education as a professionalising strategy.

This paper reports on a detailed analysis of selected findings from a larger study of master's level nurse education. It locates some features of such education within the contemporary situation of nursing as a profession and interprets the role of master's level nurse education as a professionalising strategy. In-depth interviews were undertaken with a purposive sample of 18 nurse lecturers drawn from eight universities in the United Kingdom. The interview agenda explored participants' perspectives of the characteristics of master's level performance in practice. Interview transcripts were interpreted by drawing upon hermeneutic methodology. The following themes emerged. (a) The credibility of the master's level nurse was of central importance. In terms of the literature of professionalisation, this may be interpreted as a factor in enhancing the legitimacy of nursing as an occupation. (b) The clinical capability attributed to the nurse is interpreted as leading to an increase in the authority commanded by the expert professional. Thus, the individual capability of the master's level nurse enhances the attribution of autonomous skill to the occupation as a whole. (c) The master's level nurse is seen to exercise influence and leadership and this strengthens the power and status of nursing. Nursing does not have the appearance of a 'traditional' profession, neither has it a clear stance as a 'new profession'. Rather it appears to be especially responsive to the tide of public opinion manifest through government edicts. While nursing is employing rhetoric that espouses both positions, the direction of master's level education is anomalous.