No abstract

The genetic encoding of synthetic or "non-natural" amino acids promises to diversify the functions and structures of proteins. We applied rapid codon-reassignment for creating Escherichia coli strains unable to terminate translation at the UAG "stop" triplet, but efficiently decoding it as various tyrosine and lysine derivatives. This complete change in the UAG meaning enabled protein synthesis with these non-natural molecules at multiple defined sites, in addition to the 20 canonical amino acids. UAG was also redefined in the E. coli BL21 strain, suitable for the large-scale production of recombinant proteins, and its cell extract served the cell-free synthesis of an epigenetic protein, histone H4, fully acetylated at four specific lysine sites.

The yeast estrogen screen was applied to sewage treatment process waters to identify the presence of estrogenic activity and to investigate the fate and behavior of estrogenic substances through treatment. Hydrophobic fractions in the water phase were extracted and concentrated using C18 cartridges for the effective extraction of 17β-estradiol (E2) and other estrogen mimics. Clear dose-dependent elevation in the synthesis of β-galactosidase in the yeast screen was observed with all the samples tested, demonstrating that these samples were estrogenic. However, estrogenic activity tended to reduce during the treatment, especiallyiin the biological process. Quantification results of the yeast estrogen screen in terms of E2 equivalent were compared with actual E2 concentrations measured by an ELISA. E2 occupied 34% of the whole estrogenicity in the raw sewage, while almost 100% in the final effluent. The analyses of the sewage treatment process waters revealed that human estrogens are major causative substances in terms of estrogenic activity in sewage and its treated effluent. Although findings of possible correlation of environmental estrogens with the real impact on human health and the ecosystem are still the focus of scientific debate and investigation, proper management should be established in the sewage treatment process which receives various environmental contaminants.

This paper reports two advances in a slow light device consisting of chirped photonic crystal slab coupled waveguide on SOI substrate. One is concerning the delay-bandwidth product, indicating the buffering capacity of the device. We experimentally evaluated a record high value of 57 (a 40 ps delay and a 1.4 THz bandwidth). We also observed ~1 ps wide optical pulse transmission in the cross-correlation measurement. Regarding the pulse as a signal and considering the broadening of the pulse width due to the imperfect dispersion compensation in the device, storage of more than 12 signal bits was confirmed. The other is a wide-range tuning of the pulse delay. We propose a technique for externally controlling the chirping to permit variable delay. We demonstrate tuning of the pulse delay up to 23 ps, corresponding to a ~7 mm extension of the free space length.

No abstract

Zona-free embryos at the 4-cell stage were classified into four types according to the total points of contact between the 4 blastomeres. Types A, B, C, and D had 3, 4, 5, and 6 points of contact, respectively. Embryos of these types were cultured individually in 20 microliters of Whitten's medium. Blastocysts derived from types A and D embryos at the 4-cell stage were transferred and observed on Day 17 of gestation. The number of live fetuses was significantly lower for type A than for type D embryos (p < 0.05). In spite of the removal of the zone pellucida, both types A and D blastocysts had cell numbers similar to those in zona-intact control embryos at 96 h after insemination. However, type A embryos had fewer (p < 0.05) inner cell mass (ICM) cells than did either the zona-intact control or type D embryos. Type D embryos did not have significantly fewer ICM than did the zona-intact control. Our data show that the cell association of zona-free embryos at the 4-cell stage influences differentiation of cells within the ICM and thus affects subsequent embryonic development. We suggest that one role of the zona pellucida after fertilization, in addition to protecting the preimplantation embryo, is to maintain the cell arrangement of 4-cell stage embryos to ensure subsequent successful cell lineage.

No abstract

In principle, the accumulation of knowledge regarding the molecular basis of biological systems should allow the development of large-scale kinetic models of their functions. However, the development of such models requires vast numbers of parameters, which are difficult to obtain in practice. Here, we used an in vitro translation system, consisting of 69 defined components, to quantify the epistatic interactions among changes in component concentrations through Bahadur expansion, thereby obtaining a coarse-grained model of protein synthesis activity. Analyses of the data measured using various combinations of component concentrations indicated that the contributions of larger than 2-body inter-component epistatic interactions are negligible, despite the presence of larger than 2-body physical interactions. These findings allowed the prediction of protein synthesis activity at various combinations of component concentrations from a small number of samples, the principle of which is applicable to analysis and optimization of other biological systems. Moreover, the average ratio of 2-to 1-body terms was estimated to be as small as 0.1, implying high adaptability and evolvability of the protein translation system.