From carbon dioxide to starch: no plants required Many plants turn glucose from photosynthesis into polymers that form insoluble starch granules ideal for long-term energy storage in roots and seeds. Cai et al . developed a hybrid system in which carbon dioxide is reduced to methanol by an inorganic catalyst and then converted by enzymes first to three and six carbon sugar units and then to polymeric starch. This artificial starch anabolic pathway relies on engineered recombinant enzymes from many different source organisms and can be tuned to produce amylose or amylopectin at excellent rates and efficiencies relative to other synthetic carbon fixation systems—and, depending on the metric used, even to field crops. —MAF

This work investigated the polyanion-initiated gelation process in fabricating chitosan-tripolyphosphate (CS-TPP) nanoparticles intended to be used as carriers for delivering tea catechins. The results demonstrated that the particle size and surface charge of CS-TPP nanoparticles could be controlled by fabrication conditions. For preparation of CS-TPP nanoparticles loaded with tea catechins, the effects of modulating conditions including contact time between CS and tea catechins, CS molecular mass, CS concentration, CS-TPP mass ratio, initial pH value of CS solution, and concentration of tea catechins on encapsulation efficiency and the release profile of tea catechins in vitro were examined systematically. The study found that the encapsulation efficiency of tea catechins in CS-TPP nanoparticles ranged from 24 to 53%. In addition, FT-IR analysis showed that the covalent bonding and hydrogen bonding between tea catechins and CS occurred during the formation of CS-TPP nanoparticles loaded with tea catechins. Furthermore, studies on the release profile of tea catechins in vitro demonstrated that the controlled release of tea catechins using CS-TPP nanoparticles was achievable.

The cad operon of Staphylococcus aureus plasmid pI258, which confers cadmium resistance, encodes a transcriptional regulator, CadC, and CadA, an ATP-coupled Cd(II) pump that is a member of the superfamily of cation-translocating P-type ATPases. The Escherichia coli homologue of CadA, termed ZntA, is a Zn(II)/Cd(II) pump. The results described in this paper support the hypothesis that ZntA and CadA are Pb(II) pumps. First, CadC is a metal-responsive repressor that responds to soft metals in the order Pb>Cd>Zn. Second, both CadA and ZntA confer resistance to Pb(II). Third, transport of 65 Zn(II) in everted membrane vesicles of E. coli catalyzed by either of these two P-type ATPase superfamily members is inhibited by Pb(II).Exposure to environmental sources of lead is a serious public health concern. In humans chronic lead exposure produces neurotoxicity, anemia, and kidney damage, and acute lead toxicity can be fatal. Neither the specific lead transporters nor the regulatory elements that control the expression of the transporter genes have been identified. As models for human metal toxicity, we have been characterizing transporters for toxic metals and their genetic regulation (1, 2) and report here the identification of two P-type ATPases that are responsible for Pb(II) extrusion and resistance in bacteria.Bacterial metal ion resistance probably arose early in evolution due to widespread geological occurrence of metals. Bacterial cells have chromosomally and plasmid-encoded mechanisms for extrusion of antimicrobial substances, including toxic soft metals (3). While the ionic forms of some of these metals such as zinc and copper are essential for all organisms, all of these ions are toxic in excess. ZntA from Escherichia coli and CadA from plasmid pI258 of Staphylococcus aureus are both members of the superfamily of P-type cation-translocating ATPases but belong to a subgroup of soft metal transporters that includes CopA, a Cu(I) pump from Enterococcus hirae, and eukaryotic Cu(I) homeostasis proteins such as the Menkes and Wilson disease-associated proteins (1, 4, 5). ZntA has been shown to catalyze ATP-dependent transport of Zn(II) and Cd(II) (6), and CadA has been shown to transport Cd(II) (7). Both have been shown to confer resistance to cadmium and zinc ions (8 -10). The pI258 cadCA operon is regulated at the transcriptional level by the product of the cadC gene, which encodes the 122-residue CadC repressor (11-13).In this report, we show that CadC repression of the cad promoter is relieved upon addition of soft metals, with the order of effectiveness Pb(II) Ͼ Cd(II) Ͼ Zn(II). In E. coli Zn(II) responsiveness could be observed only in a zntA-disrupted strain. The zntA-disrupted strain of E. coli exhibited hypersensitivity to Pb(II) that was complemented by cadA, indicating that both soft metal-translocating P-type ATPases are essential for Pb(II) resistance in bacteria. Everted membrane vesicles from cells expressing either zntA or cadA exhibited ATPdependent 65 Zn(II) accumulation. Since no radioisotopes of ...

These findings suggest that KDC and FBT could attenuate features of the metabolic syndrome in HFD-fed mice, which might be due to the modulation of gut microbiota by KDC and FBT.

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