The resonance light-scattering technique, using a spectrofluorometer, was first developed as a sensitive instrumental analysis method. At pH 7.48 and ionic strength 0.004, the extent of light-scattering of alpha, beta, gamma, delta-tetrakis[4-(trimethylammoniumyl)phenyl]porphine (TAPP) is enhanced by nucleic acids near 432 nm. There are linear relationships between the enhanced extents of light-scattering and the concentrations of nucleic acids in the range of 1.8 x 10(-7)-10.8 x 10(-7) M for calf thymus and fish sperm DNA and in the range of 1.8 x 10(-7)-1.8 x 10(-6) M for yeast RNA. The limit of determination (3 sigma) is 4.1 x 10(-8) M for calf thymus DNA, 4.6 x 10(-8) M for fish sperm DNA, and 6.7 x 10(-8) M for yeast RNA. Mechanism study indicates that nucleic acids react with the title porphyrin in two modes, depending on the concentrations of nucleic acids. When the molar ratio of nucleic acids to TAPP is smaller than 4:1, the hypochromicity and fluorescence quenching of TAPP by nucleic acids appear, and the enhancement of resonance light-scattering can be observed. When the molar ratio of nucleic acids to TAPP is larger than 4:1, a new fluorescent complex is formed.

Using a common spectrofluorometer to measure the intensity of resonance light-scattering, a method for determination of nucleic acids in the nanogram range has been developed. In the pH range 11.5-12.0, the resonance light-scattering of the binary complex of cobalt(II)/ 4-[(5-chloro-2-pyridyl)azo]-1,3-diaminobenzene (5-Cl-PADAB) is greatly enhanced by nucleic acids, with the maximum scattering peak located at 547.0 nm. The enhanced intensity of resonance light-scattering is in proportion to the concentration of calf thymus DNA in the range 0-400 ng/mL and to that of fish sperm DNA and yeast RNA in the range 0-300 ng/mL. The limits of detection are 1.4 ng/mL for calf thymus DNA, 0.8 ng/ mL for fish sperm DNA, and 1.3 ng/mL for yeast RNA. Precision at 200 ng/mL for the three nucleic acids is 1.9%, 2.0%, and 0.8%, respectively. Six synthetic samples were determined satisfactorily. Mechanism studies showed that the nature of the reaction is that the binary complex of Co(II)/5-Cl -PADAB reacts with single-stranded nucleic acid, and the enhancement effect of nucleic acids on the resonance light scattering of the binary complex is due to the stacking of the binary complex on nucleic acids, which act as a template.

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Notwithstanding the remarkable progress in the clinical treatment of ischemic disease, proangiogenic drugs mostly suffer from their abnormal angiogenesis and potential cancer risk, and currently, no off-the-shelf biomaterials can efficiently induce angiogenesis. Here, we reported that a semisynthetic sulfated chitosan (SCS) readily engaged anti-inflammatory macrophages and increased its secretion of endogenous vascular endothelial growth factor (VEGF) to induce angiogenesis in ischemia via a VEGF-VEGFR2 signaling pathway. The depletion of host macrophages abrogated VEGF secretion and vascularization in implants, and the inhibition of VEGF or VEGFR2 signaling also disrupted the macrophage-associated angiogenesis. In addition, in a macrophage-inhibited mouse model, SCS efficiently helped to recover the endogenous levels of VEGF and the number of CD31hiEmcnhi vessels in ischemia. Thus, both sulfated group and pentasaccharide sequence in SCS played an important role in directing the therapeutic angiogenesis, indicating that this highly bioactive biomaterial can be harnessed to treat ischemic disease.

Change in temperature is often a major environmental factor in triggering waterborne disease outbreaks. Previous research has revealed temporal and spatial patterns of bacterial population in several aquatic ecosystems. To date, very little information is available on aquaculture environment. Here, we assessed environmental temperature effects on bacterial community composition in freshwater aquaculture system farming of Litopenaeus vannamei (FASFL). Water samples were collected over a one-year period, and aquatic bacteria were characterized by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) and 16S rDNA pyrosequencing. Resulting DGGE fingerprints revealed a specific and dynamic bacterial population structure with considerable variation over the seasonal change, suggesting that environmental temperature was a key driver of bacterial population in the FASFL. Pyrosequencing data further demonstrated substantial difference in bacterial community composition between the water at higher (WHT) and at lower (WLT) temperatures in the FASFL. Actinobacteria, Proteobacteria and Bacteroidetes were the highest abundant phyla in the FASFL, however, a large number of unclassified bacteria contributed the most to the observed variation in phylogenetic diversity. The WHT harbored remarkably higher diversity and richness in bacterial composition at genus and species levels when compared to the WLT. Some potential pathogenenic species were identified in both WHT and WLT, providing data in support of aquatic animal health management in the aquaculture industry.