Scoping studies to establish the capability and utility of a real-time bioaerosol sensor to characterise emissions from environmental sources.

A novel dual excitation wavelength based bioaerosol sensor with multiple fluorescence bands called Spectral Intensity Bioaerosol Sensor (SIBS) has been assessed across five contrasting outdoor environments. The mean concentrations of total and fluorescent particles across the sites were highly variable being the highest at the agricultural farm (2.6 cm-3 and 0.48 cm-3, respectively) and the composting site (2.32 cm-3 and 0.46 cm-3, respectively) and the lowest at the dairy farm (1.03 cm-3 and 0.24 cm-3, respectively) and the sewage treatment works (1.03 cm-3 and 0.25 cm-3, respectively). In contrast, the number-weighted fluorescent fraction was lowest at the agricultural site (0.18) in comparison to the other sites indicating high variability in nature and magnitude of emissions from environmental sources. The fluorescence emissions data demonstrated that the spectra at different sites were multimodal with intensity differences largely at wavelengths located in secondary emission peaks for λex 280 and λex 370. This finding suggests differences in the molecular composition of emissions at these sites which can help to identify distinct fluorescence signature of different environmental sources. Overall this study demonstrated that SIBS provides additional spectral information compared to existing instruments and capability to resolve spectrally integrated signals from relevant biological fluorophores could improve selectivity and thus enhance discrimination and classification strategies for real-time characterisation of bioaerosols from environmental sources. However, detailed lab-based measurements in conjunction with real-world studies and improved numerical methods are required to optimise and validate these highly resolved spectral signatures with respect to the diverse atmospherically relevant biological fluorophores.

Molecular and morphological evidence for cadaver vitreous-stimulated transformation of differentiation-competent retinal pigment epithelial cells into neuron-like cells.

Retinal pigment epithelia (RPE) and retinal neurons (RN) arise from the same underlying precursor cell population. It is worthwhile to explore the transdifferentiation potential of RPE cells, given the benefits that could accrue from turning RPE into neural retina containing all its normal cellular subpopulations. Factors such as retinoic acid (RA, acting as an inducer of transdifferentiation) and epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF) (E+F, acting as stem cell maintenance and predifferentiating factors) have been known to stimulate the conversion of RPE into observably neuron-like cells. However, since such treatment does not actually transform RPE into neurons, there is a need to rationally explore the efficacy of other factors as well. In this paper, we have compared the effects of RA, a known transdifferentiating factor in optical and other tissues, with the effects of cadaver vitreous on D407 RPE cells, using a combination of light microscopy, immunofluorescent microimaging and flow cytometry. We show that cadaver-derived vitreous (CV) is comparable to, or better than, RA as a transdifferentiation factor in an EGF + bFGF maintenance background. The vitreous humor could thus be an important stimulator of the differentiation of dedifferentiated RPE cells into neurons. This finding assumes significance in light of the fact that vitreous humor is a factor naturally present in the environment of the developing retina.

Expression of granulocyte colony stimulating factor and its receptor by retinal pigment epithelial cells: a role in maintaining differentiation-competent state.

PURPOSE: Granulocyte colony stimulating factor (GCSF) is a potent hematopoietic factor that stimulates the growth of neutrophil granulocyte precursors, and also regulates the differentiation and survival of neutrophils by inhibiting apoptosis. Incidentally, GCSF is also known to act as an endogenous ligand for brain cells, counteracting acute neuronal degeneration and contributing to long-term plasticity of progenitor cells after cerebral ischemia. Since GCSF was recently reported to be present in retinal ganglions, we examined its expression in retinal pigment epithelial (RPE) cells, which, together with retinal neurons, arise from the same underlying precursor cells. METHODS: We used reverse transcriptase polymerase chain reaction (PCR) to assay expression of GCSF and GCSF receptor (GCSFR) genes; immunostaining and flow cytometry to assay the presence of GCSFR on cell surfaces; bromodeoxyuridine (BrdU) incorporation measurement to monitor DNA synthesis; and 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay to monitor cell proliferation. The effect of GCSF on differentiation of RPE cells was assessed by immunocytochemistry to detect the presence of various marker proteins. RESULTS: The D407 RPE cells, as well as RPE derived from cadaver eyes, were found to express both GCSF and GCSFR. Despite the presence of the GCSF receptor, exogenously added GCSF did not result in any proliferation of these cells. We found that GCSF acts like a de-differentiating factor, maintaining RPE cells in the rounded form, and in a transdifferentiation-competent state. CONCLUSIONS: The expression of GCSF and GCSFR by D407 RPE may be an important factor in RPE cell maintenance.