Gulture medium composition is critical for the successful induetion of microspore division tn vitro.The present experiments have focused on a relatively neglected area of cell and tissue culture research, namely the carbohydrate eomponent used in the medium. Three spring barley genotypes were cultured on a medium whieh was modified by replacing sucrose with the following carbohydrates (6 % w/v): maltose, fructose, malt extract, galactose and a glucose (3 % w/v)/fructose (3 % w/v) mixture. Both maltose and malt extract were superior to sucrose in their capacity to induce green plantlet differentiation from microspores. The concentrations of both suerose and maltose were also varied. Overall the response of anthers on maltose based tnedia was higher than on sucrose based media, [furthermore, a eoncentration of maltose in the range 6-12 % w/v produced a higher frequeney of green plants than a low concentration (1-3 % w/v). The effect of maltose based media on germplasm of direct relevance to barley breeders was also tested. The cultivar 'Blenheim' was shown to be very responsive and this genetic factor was transmitted to the Fi hybrid. The frequency of haploid to diploid regenerants was not eonsistent over genotypes, but in general there were more haploid than diploid regenerants. The implications of these results for barley breeding are discussed.
W. 1991. Genetic stability of microspore-derived doubled haploids of barley: a cytological, biochemical, and molecular study. Genome, 34: 923-928. Populations of doubled haploids were produced by culturing microspores from spring barley cv. Tweed, cv. Tyne, and cv. Natasha, on media containing either sucrose or maltose as the only carbohydrate. The populations were analysed for evidence of genetic instability at the karyotype, protein, and DNA levels. The results show very little evidence of induced genetic change. The level of instability is insignificant when compared with that which is observed following meiotic recombination. The stability of microspore-derived lines may be attributed to the embryogenic mode of regeneration, which occurs at a high frequency on a maltose-containing medium. The results are discussed in relation to the exploitation of doubled haploids in barley breeding. et POWELL, W. 1991. Genetic stability of microspore-derived doubled haploids of barley: a cytological, biochemical, and molecular study. Genome, 34 : 923-928. Des populations d'haploi'des doublees ont ete produites par culture d'androspores d'orge de printemps : cv. Tweed, cv. Tyne et cv. Natasha, sur des milieux contenant soit du sucrose ou du maltose comme seule source d'hydrate de carbone. Les populations ont ete analysees pour les evidences d'instabilite genetique aux niveaux du caryotype, des proteines et de I'ADN. Les resultats montrent trks peu d'evidences de changements induits. Le niveau d'instabilite n'est pas significatif, lorsqu'il est compare a celui qui est observe au cours de la recombinaison meiotique. La stabilite des lignees derivees d'androspores peut 2tre attribuee au mode embryogenique de la regeneration qui survient a une frequence elevee, sur un milieu contenant du maltose. Les resultats sont discutes en regard de l'exploitation des haploi'des doublees dans les programmes d'amelioration de l'orge.
Introduction MicroRNAs are promising biomarkers of renal disease, however the cellular origin of their expression is usually unclear limiting their interpretation when measured in renal biopsies and urine. We hypothesised that by first defining renal cell-enriched microRNAs, we could select biomarkers based on the expected histopathological profile. Method Small RNA-sequencing of cortical, proximal tubular (LTL), macrophage (F480), endothelial (CD31) and fibroblast (PDGFRb) populations from the reversible unilateral ureteric obstruction (rUUO) murine model was performed. Hierarchical clustering was used to identify clusters. Findings were translated into an ischaemia reperfusion injury (IRI) model and then into urine samples from renal transplant recipients (n=16) with delayed graft function (DGF) vs. those with primary function. Result Kidney injury resulted in significant macrophage infiltration and tubular injury which improved upon reversal. We characterised novel microRNA clusters enriched for each cell type. With injury there was a significant increase in macrophage (p<0.0001), fibroblast (p<0.01) and decrease in proximal tubule (p<0.0001) enriched microRNAs vs. non-enriched microRNAs. We validated macrophage enriched miR-18a, miR-16 and tubular enriched miR-194 in the IRI model, demonstrating that microRNA expression reflected the histological profile. In humans, urinary miR-16 (FC 16.9; p<0.05) and miR-18a (FC 10: p=0.06) were upregulated at day 2 in patients with DGF; outperforming the traditional injury marker KIM1. Conclusion This is the first study to characterise cell-enriched microRNAs during renal injury and repair. By defining the source of microRNA expression we were able to rationally select miR-16 and miR-18a as promising urinary biomarkers of renal injury. Take-home message We have found that microRNAs have differences in expression between cell types and renal injury states which is important when considering microRNA expression in samples composed of varying cellular composition. By defining the cellular origins of microRNA expression we were able to rationally select microRNA biomarkers of human renal injury.
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