ABSTRACT
A terminal deoxynucleotidyl transferase ( TdT ) amplification based DNA-copper nanoclusters (CuNCs) sensor was developed for detection of L-histidine ( L-His). Single strand DNA containing poly-thymine ( T) sequences were synthesized by TdT in the presence of dTTP. In blank control, poly-T sequences worked as templates of CuNCs due to the affinity between thymine and copper ions( II) . Fluorescence intensity was enhanced when CuNCs formed with reducing agents. In the presence of L-His, the imidazolyl group of L-His worked as a chelating agent that formed L-His-Cu2+ chelated complex. Thus less copper ions were induced in poly-T sequences, and less CuNCs were obtained to produce week fluorescence signals. A good linear correlation was obtained between fluorescence change and the logarithm of the L-His concentration over the range of 5. 0 ×10-9-5. 0 ×10-4 mol/L. The detection limit was estimated as 3. 4 ×10-9 mol/L. And the recoveries were 97. 4%-104. 6% for the actual urine samples. Compared with other methods of synthetic CuNCs, this method allowed to specifically determining L-histidine without template or labeling, which showed good potential in biomedical and clinical analysis.
ABSTRACT
The role of intestinal microbiota in mammals and humans are gaining increasing attention. The health of piglets requires a dynamically balanced intestinal microbiota. However, there are temporal and spatial changes in the distri-bution and composition of microbiota from the esophagus to the rectum during the life cycle of the pig. The intestinal micro?biota has various beneficial functions in pig, like nutrient metabolism, intestinal mucosal barrier, immune responses and pathogen infection. A variety of factors play an important role in the formation and stabilization of intestinal microbiota, in?cluding the ways of delivery ( vaginal or caesarean) , the diet during infancy ( breast milk or formula feeds) and the usage of antibiotics or antibiotic-like molecules. In this review, we mainly discussed the relationship between intestinal microbi?ota and the intestinal health of piglets from the aspects of the composition and colonization of intestinal microbiota, as well as the functions and influencing factors of intestinal microbiota, so as to further understanding the importance of intestinal microbiota in intestinal function of piglets.
ABSTRACT
A terminal deoxynucleotidyl transferase ( TdT ) amplification based DNA-copper nanoclusters (CuNCs) sensor was developed for detection of L-histidine ( L-His). Single strand DNA containing poly-thymine ( T) sequences were synthesized by TdT in the presence of dTTP. In blank control, poly-T sequences worked as templates of CuNCs due to the affinity between thymine and copper ions( II) . Fluorescence intensity was enhanced when CuNCs formed with reducing agents. In the presence of L-His, the imidazolyl group of L-His worked as a chelating agent that formed L-His-Cu2+ chelated complex. Thus less copper ions were induced in poly-T sequences, and less CuNCs were obtained to produce week fluorescence signals. A good linear correlation was obtained between fluorescence change and the logarithm of the L-His concentration over the range of 5. 0 ×10-9-5. 0 ×10-4 mol/L. The detection limit was estimated as 3. 4 ×10-9 mol/L. And the recoveries were 97. 4%-104. 6% for the actual urine samples. Compared with other methods of synthetic CuNCs, this method allowed to specifically determining L-histidine without template or labeling, which showed good potential in biomedical and clinical analysis.