Fluorescent Nanoparticles Synthesized from DNA, RNA, and Nucleotides.

Ubiquitous on Earth, DNA and other nucleic acids are being increasingly considered as promising biomass resources. Due to their unique chemical structure, which is different from that of more common carbohydrate biomass polymers, materials based on nucleic acids may exhibit new, attractive characteristics. In this study, fluorescent nanoparticles (biodots) were prepared by a hydrothermal (HT) method from various nucleic acids (DNA, RNA, nucleotides, and nucleosides) to establish the relationship between the structure of precursors and fluorescent properties of biodots and to optimize conditions for preparation of the most fluorescent product. HT treatment of nucleic acids results in decomposition of sugar moieties and depurination/depyrimidation of nucleobases, while their consequent condensation and polymerization gives fluorescent nanoparticles. Fluorescent properties of DNA and RNA biodots are drastically different from biodots synthesized from individual nucleotides. In particular, biodots synthesized from purine-containing nucleotides or nucleosides show up to 50-fold higher fluorescence compared to analogous pyrimidine-derived biodots. The polymeric nature of a precursor disfavors formation of a bright fluorescent product. The reported effect of the structure of the nucleic acid precursor on the fluorescence properties of biodots should help designing and synthesizing brighter fluorescent nanomaterials with broader specification for bioimaging, sensing, and other applications.

Metal Ions Sensing by Biodots Prepared from DNA, RNA, and Nucleotides.

Nucleic acids that exhibit a high affinity toward noble and transition metal ions have attracted growing attention in the fields of metal ion sensing, toxic metal ion removal, and the construction of functional metal nanostructures. In this study, fluorescent nanoparticles (biodots) were synthesized from DNA, RNA, and RNA nucleotides (AMP, GMP, UMP, and CMP) using a hydrothermal (HT) method, in order to study their metal ion sensing characteristics. The fluorescent properties of biodots differ markedly between those prepared from purine and pyrimidine nucleobases. All biodots demonstrate a high sensitivity to the presence of mercury cations (Hg2+), while biodots prepared from DNA, RNA, and guanosine monophosphate (GMP) are also sensitive to Ag+ and Cu2+ ions, but to a lesser extent. The obtained results show that biodots inherit the metal ion recognition properties of nucleobases, while the nucleobase composition of biodot precursors affects metal ion sensitivity and selectivity. A linear response of biodot fluorescence to Hg2+ concentration in solution was observed for AMP and GMP biodots in the range 0-250 µM, which can be used for the analytic detection of mercury ion concentration. A facile paper strip test was also developed that allows visual detection of mercury ions in solutions.

Supplementation of amylase combined with glucoamylase or protease changes intestinal microbiota diversity and benefits for broilers fed a diet of newly harvested corn.

BACKGROUND: The effect of amylases combined with exogenous carbohydrase and protease in a newly harvested corn diet on starch digestibility, intestine health and cecal microbiota was investigated in broiler chickens. METHODS: Two hunderd and eighty-eight 5-day-old female chickens were randomly divided into six treatments: a newly harvested corn-soybean meal diet (control); control supplemented with 1,500 U/g α-amylase (Enzyme A); Enzyme A + 300 U/g amylopectase + 20,000 U/g glucoamylase (Enzyme B); Enzyme B + protease 10,000 U/g (Enzyme C); Enzyme C + xylanase 15,000 U/g (Enzyme D); and Enzyme D + cellulase 200 U/g + pectinase 1,000 U/g (Enzyme E). Growth performance, starch digestibility, digestive organ morphology, and intestinal microbiota were evaluated in the birds at 16 and 23 d of age. RESULTS: Compared with the control diet, supplementation with Enzyme A significantly decreased ileum lesion scoring at 16 d of age (P < 0.05); supplementation with Enzyme B or Enzyme C showed positive effects on ileal amylopectin and total starch digestibility (P < 0.05); Broilers fed with a diet supplemented with Enzyme D had a tendency to decrease body weight gain at 23 d. Enzyme E supplementation improved lesion scoring of jejunum and ileum at 16 d (P < 0.05), and increased ileal amylopectin or total starch digestibility at 23 d (P < 0.05). Supplementation of enzymes changed cecal microbiota diversity. High numbers of Campylobacter, Helicobacter and Butyricicoccus, Anaerostipes and Bifidobacterium, Sutterella and Odoribacter were the main genera detected in supplementations with Enzymes B, C, D, and E respectively. CONCLUSIONS: Supplementation with amylase combined with glucoamylase or protease showed a beneficial effect on starch digestibility and intestinal microbiota diversity, and increased growth of broilers fed with newly harvested corn.

Effect of different amylases on the utilization of cornstarch in broiler chickens.

This study compared the effect of different amylases on the utilization of cornstarch in broiler chickens fed a corn-based diet. Three-day-old Arbor Acres plus male chickens were randomly divided into 7 treatments and fed a diet supplemented with different sources and concentrations of amylase: 1,500 U/kg and 3,000 U/kg α-1,4 amylase from Aspergillus oryzae (α-amylase A); 480 U/kg and 960 U/kg α-1,4 amylase from Bacillus subtilis (α-amylase B); 200 U/kg and 400 U/kg α-1,6 isoamylase from B. subtilis; and the control. The experimental period comprised 11 d, during which performance, nutrient digestibility, digestive enzyme activity, intestinal morphology, and glucose transporter transcription of the chickens were evaluated. The results indicated that 1,500 U/kg α-amylase improved the digestibility of energy and decreased the feed conversion rate compared to α-1,6 isoamylase (P < 0.05). Supplemental 400 U/kg α-1,6 isoamylase decreased ileal digestibility of amylopectin and total starch (P < 0.05) compared to 200 U/kg α-1,6 isoamylase, α-amylase A, α-amylase B, and the control (P < 0.05). Supplemental α-1,6 isoamylase decreased (P < 0.05) insulin content. Supplemental 3,000 U/kg α-amylase A and α-1,6 isoamylase increased (P < 0.05) the relative weight of the liver. In addition, 3,000 U/kg α-amylase A, 480 U/kg α-amylase B, and α-1,6 isoamylase decreased the V:C in the duodenum and ileum. α-amylase A increased sucrase activity in the jejunum (P < 0.05), whereas 400 U/kg α-1,6 isoamylase reduced maltase activity in the duodenum (P < 0.05). Furthermore, 3,000 U/kg α-amylase A and α-amylase B decreased (P < 0.05) sodium/glucose cotransporter 1 (SGLT1) mRNA expression in the duodenum and jejunum. However, 200 U/kg α-1,6 isoamylase increased glucose transporter 2 (GLUCT2) in the duodenum (P < 0.05). These results suggest that exogenous amylase affects the digestibility of starch by affecting disaccharidase activity in the intestine, nutrient requirements for intestinal maintenance by the V:C, and nutrient absorption and metabolism via GLU transporter mRNA expression. Different sources and concentrations of amylases had varying effects on broilers.