Algae biosorption is an ideal wastewater treatment method when coupled with algae growth and biosorption. The adsorption and bioaccumulation of strontium from simulated nuclear wastewater by Scenedesmus spinosus were investigated in this research. One hundred mL of cultured S. spinosus cells with a dry weight of 1.0 mg in simulated nuclear wastewater were used to analyze the effects on S. spinosus cell growth as well as the adsorption and bioaccumulation characters under conditions of 25 ± 1 °C with approximately 3,000 lux illumination. The results showed that S. spinosus had a highly selective biosorption capacity for strontium, with a maximum bioremoval ratio of 76%. The adsorbed strontium ion on cell walls was approximately 90% of the total adsorbed amount; the bioaccumulation in the cytoplasm varied by approximately 10%. The adsorption quantity could be described with an equilibrium isotherm. The pseudo-second-order kinetic model suggested that adsorption was the rate-limiting step of the biosorption process. A new bioaccumulation model with three parameters was proposed and could give a good fit with the experiment data. The results suggested that S. spinosus may be a potential biosorbent for the treatment of nuclear wastewater in culture conditions.
The liquid crystalline state is a universal phenomenon involving the formation of an ordered structure via a self-assembly process that has attracted attention from numerous scientists. In this study, the dinoflagellate histone-like protein HCcp3 is shown to induce super-coiled pUC18 plasmid DNA to enter a liquid crystalline state in vitro, and the role of HCcp3 in gene condensation in vivo is also presented. The plasmid DNA (pDNA)-HCcp3 complex formed birefringent spherical particles with a semi-crystalline selected area electronic diffraction (SAED) pattern. Circular dichroism (CD) titrations of pDNA and HCcp3 were performed. Without HCcp3, pUC18 showed the characteristic B conformation. As the HCcp3 concentration increased, the 273 nm band sharply shifted to 282 nm. When the HCcp3 concentration became high, the base pair (bp)/dimer ratio fell below 42/1, and the CD spectra of the pDNA-HCcp3 complexes became similar to that of dehydrated A-form DNA. Microscopy results showed that HCcp3 compacted the super-coiled gene into a condensed state and that inclusion bodies were formed. Our results indicated that HCcp3 has significant roles in gene condensation both in vitro and in histone-less eukaryotes in vivo. The present study indicates that HCcp3 has great potential for applications in non-viral gene delivery systems, where HCcp3 may compact genetic material to form liquid crystals.
In previous studies, we established an animal model of human congenital hydronephrosis with exposure of developing mice to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), but the etiopathogenesis is not entirely clear. The present study was to identify the changes that may be involved in the etiology at the protein level.
Few studies have focused on biosorption by microorganisms under culture conditions. To explore the biosorption of uranium by Saccharomyces cerevisiae under culture conditions, the S. cerevisiae growth curve, biosorption capacity and surface interaction under batch culture conditions were investigated in this study. The growth curve showed that uranium (<300mgL(-1)) did not markedly inhibit the growth of S. cerevisiae under short culture time. The maximum scavenging efficiency reached 92.4% under 6-10h culture conditions, and the adsorption quantity of S. cerevisiae increased with initial uranium concentration. Centrifuging and drying after biosorption caused the volume reduction ratio to reach 99%. Scanning electron microscope results demonstrated that uranium interacted with yeast cell surfaces, as well as culture medium, and produced uranium precipitate on cell surfaces. Fourier transformed infrared spectra revealed that cell walls were the major sorption sites, and -O--H, -C==O and -PO(2-) contributed to the major binding groups.
Liquid crystalline phases of DNA and nucleosome core particles can be formed in vitro, indicating the crucial roles of these phases in the maintenance and compaction of genomes in vivo. In the present study, sequential levels of liquid crystalline decompaction were identified in highly purified nuclei of Karenia papilionacea in response to the gradual chelation of divalent counterions by ethylenediaminetetraacetic acid (EDTA); the decompaction was observed using polarizing light microscopy, confocal laser scanning microscopy, and transmission electron microscopy and further confirmed utilizing microcalorimetry. Nested fibrous coils in 150?nm arc-like bands of chromatin were observed in the early stages of chromosomal decompaction. The microcalorimetry spectra of isolated nuclei revealed that the dynamic processes of nuclear decompaction occurred in a nonlinear manner; in addition, an EDTA-sensitive thermal transition between 60°C-70°C, corresponding to a liquid-crystalline-phase transition of chromosomes, was found. The results suggested that nested coils of fibrous chromatin filaments are responsible for the establishment and stabilization of the liquid crystalline and birefringence features of the chromosomes of dinoflagellates. The results also indicated that positively charged divalent counterions play significant roles in modulating liquid crystalline phases to compact the chromosomes of dinoflagellates.
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