PEG modification enhances the in vivo stability of bioactive proteins immobilized on magnetic nanoparticles.

OBJECTIVE: To increase the in vivo stability of bioactive proteins via optimized loading methods. RESULTS: ß-Glucosidase (ß-Glu), as a model protein, was immobilized on magnetic nanoparticles(denoted as MNP-ß-Glu) by chemical coupling methods and was further modified by poly(ethylene glycol) (PEG) molecules (denoted as MNP-ß-Glu-PEG) to increase its stability. The physicochemical properties of the as-prepared nanohybrids, including the particle size, zeta potential, and enzyme activity, were well characterized. The proper MNP/ß-Glu feed ratio was important for optimizing the particle size. Analysis of enzyme activity showed that the stability of immobilized ß-Glu compared with free ß-Glu was lower in deionized water and higher in blood serum at 37 °C. MNP-ß-Glu-PEG retained 77.9% of the initial activity within 30 days at 4 °C, whereas the free enzyme retained only 58.2%. Pharmacokinetic studies of Sprague-Dawley (SD) rats showed that the MNP-ß-Glu-PEG group retained a higher enzyme activity in vivo (41.46% after 50 min) than the MNP-ß-Glu group (0.03% after 50 min) and the ß-Glu group (0.37% after 50 min). Moreover, in contrast to the MNP-ß-Glu group, the enzyme activity was not fully synchronous with the decrease in the Fe concentration in the MNP-ß-Glu-PEG group. CONCLUSIONS: All findings indicated that the method of immobilization on magnetic nanoparticles and PEG modification is promising for the application of bioactive proteins in vivo.

The Chromosome-Based Rubber Tree Genome Provides New Insights into Spurge Genome Evolution and Rubber Biosynthesis.

The rubber tree, Hevea brasiliensis, produces natural rubber that serves as an essential industrial raw material. Here, we present a high-quality reference genome for a rubber tree cultivar GT1 using single-molecule real-time sequencing (SMRT) and Hi-C technologies to anchor the ∼1.47-Gb genome assembly into 18 pseudochromosomes. The chromosome-based genome analysis enabled us to establish a model of spurge chromosome evolution, since the common paleopolyploid event occurred before the split of Hevea and Manihot. We show recent and rapid bursts of the three Hevea-specific LTR-retrotransposon families during the last 10 million years, leading to the massive expansion by ∼65.88% (∼970 Mbp) of the whole rubber tree genome since the divergence from Manihot. We identify large-scale expansion of genes associated with whole rubber biosynthesis processes, such as basal metabolic processes, ethylene biosynthesis, and the activation of polysaccharide and glycoprotein lectin, which are important properties for latex production. A map of genomic variation between the cultivated and wild rubber trees was obtained, which contains ∼15.7 million high-quality single-nucleotide polymorphisms. We identified hundreds of candidate domestication genes with drastically lowered genomic diversity in the cultivated but not wild rubber trees despite a relatively short domestication history of rubber tree, some of which are involved in rubber biosynthesis. This genome assembly represents key resources for future rubber tree research and breeding, providing novel targets for improving plant biotic and abiotic tolerance and rubber production.

[Studies on properties of aggregates and Langmuir-Blodgett films for centrosymmetric naphthalocyanine molecules].

Deposition of Langmuir-Blodgett films and the aggregative properties of three centrosymmetric naphthalocyanine derivatives were investigated by using linear absorption spectra. Good LB films could be formed for all the three compounds. In dilute solution,the monomers are the main formation for the tetra-tert-butyl-cyan naphthalocyanine. Due to atomic zinc action, the tetra-tert-butyl naphthalocyanine zinc molecules could not only form H-aggregates, but also form J-aggregates. The tetra-tert-butyl naphthalocyanine zinc molecules mainly are aggregates in dilute solution. In the Langmuir-Blodgett films, both tetra-tert-butyl-cyan naphthalocyanine and tetra-tert-butyl-cyan naphthalocyanine zinc formed H-aggregates. The monomers are the main formation for the bi-( tetra-tertbutyl-naphthalocyaninato)-orbium in dilute solution and Langmuir-Blodgett films.