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Six cell-free extracts have been used to characterize the nature of DNA signals and trans-acting factors responsible for the transcription enhancement of the Bombyx moH fibroin gene. The upstream element of the fibroin gene involved in the enhancement can be divided into two regions. The proximal region, -72 to -32, is recognized as a common enhancing signal by all B. mon extracts from the posterior silk gland, the middle silk gland, the ovarian tissue, and an embryonic cell line. It is weakly recognized by an Antheraea silkworm cell line extract but not by a HeLa cell extract. The distal region, -238 to -73, appears to be a tissue-specific enhancing signal that is recognized more effectively by the posterior silk gland extract than by the middle silk gland extract. These observations suggest that the use of these cell-free systems can offer a means for the biochemical characterization of the trans-acting factors involved in the tissuespecific regulation of the fibroin gene.

A significant number of new chemical entities (NCEs) disappear due to cytochrome P450 (CYP)-mediated clinical drug-drug interactions in drug discovery. Therefore, a high throughput assay of CYP activities is necessary in order to evaluate the inhibitory or inducible potencies of CYP isoforms with NCEs in early drug discovery. Here, we developed and validated a high-throughput assay to simultaneously monitor the in vitro activities of 8 CYP isoforms. A cocktail of 9 probe substrates for the 8 major CYPs (CYP1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, and CYP3A4/5) was incubated with human liver microsomes. Each substrate-derived metabolite was simultaneously analyzed by multiple reactions monitoring with a single ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) run using stable isotope-labeled internal standards. The ultra-fast UPLC gradient allowed each metabolite to be separated within 1 min, providing quantitative linearity of over 2 orders of magnitude. CYP inhibition by 8 well-known inhibitors was confirmed by comparing single substrates with the substrate cocktail. The inhibition curve profiles and IC₅₀ values for all CYPs in the cocktail substrate were similar to those of single substrates. UPLC-MS/MS using a CYP substrate cocktail is a reliable and robust high-throughput method to accurately assess CYP inhibition potencies of newly developed drugs.

The crystal structure of Rochelle salt in the ferroelectric phase is studied by means of x-ray diffraction. The structures of the two paraelectric phases are also redetermined to obtain the displacements of the atoms owing to the phase transitions. Cooperative displacements of the atoms responsible for the appearance of the spontaneous polarization are obtained. The displacements consist of the movements of the tartrate molecules and the water molecules in a frame composed of K and Na ions. During the successive phase transitions there are several interatomic distances maintained constant. The direction of planes made of carbons of the tartrate molecules is practically unchanged throughout the phase transitions.