A PHOTON COUNTING TV CAMERA EQUIPPED WITH AN IMAGE GUIDE FOR RAPID DETECTION AND COUNTING OF SINGLE BACTERIA IN A WIDE FIELD

Abstract— We developed a photon counting TV camera system, which uses an image guide consisting of tapered optical fibers, for the rapid detection and counting of microscopic sized luminous particles in a wide field. Using a luminous bacterium as a standard, we compared this image guide-coupled TV camera to a lens-coupled TV camera by determining their light collecting powers and detection abilities for single bacteria on a membrane filter. The image guide shortened the detection time by an order of magnitude, making the photon counting TV camera a practical system for rapid counting of bacteria.     

Highly oriented aragonite nanocrystal-biopolymer composites in an aragonite brick of the nacreous layer of Pinctada fucata

13C CP/MAS NMR and FE/TEM measurements of the aragonite brick of the nacreous layer of Pinctada fucata indicate that it assembles with highly oriented aragonite nanocrystals, which are regulated by biopolymers.     

Enhanced responses in matrix-assisted laser desorption/ionization mass spectrometry of peptides derivatized with arginine via a C-terminal oxazolone

We have developed a novel method for enhancing the response of a peptide in matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) by activating the C-terminal carboxyl group through an oxazolone with which is coupled an amine containing a functional group to help ionize the peptide. The reactions consist of dehydration with acetic anhydride to give an oxazolone, followed by aminolysis with an appropriate amino acid derivative such as arginine methyl ester. The MALDI signal of Ac-Tyr-Gly-Gly-Phe-Leu-Arg-OMe, thus converted from leucine-enkephalin, was detected while completely excluding the responses of arginine-deficient peptides coexisting in the reaction mixture. Some less intense peaks corresponding to a few sequential degradation products, also terminated with the arginine derivative, were also observed. The side-chain groups potentially that are reactive were conveniently protected by acetylation simultaneous with the C-terminal activation, and those that remained unprotected were reduced to virtually negligible proportions when the reaction was conducted in a peptide solution of concentration less than 1 mM. The greatly increased responses of such arginine-terminated peptides could possibly be exploited to discern the C-terminal tryptic peptide of a protein that is otherwise almost insensitive to MALDI-MS in general. The simplicity of the post-source decay spectrum of enkephalin derivatized by arginine methyl ester characteristically accentuated z- and b-type ions, and this should facilitate sequencing of such derivatized peptides. Remaining problems with practical applications of this approach are discussed.     

Cyclic tetrapeptides bearing a sulfhydryl group potently inhibit histone deacetylases

New inhibitors of histone deacetylase (HDAC) containing a sulfhydryl group were designed on the basis of the corresponding hydroxamic acid (CHAP31) and FK228. Their disulfide dimers and hybrids exhibited potent HDAC inhibitory activity in vivo with potential as anticancer prodrugs. [structure: see text]     

A facile route to 4,5,6,7-tetrahydrothiophenes and benzothiophenes

2-Substituted tetrahydro- and cyclopentathiophenes 2 were produced in high yields by treatment of the semi-cyclic trisubstituted 1,4-diketones 1 such as 2-phenacylcyclohexan-1-one, 2-acetonylcyclohexan-1-one, and 2-phenacylcyclopentan-1-one, with Lawesson's reagent.     

The coloration of tungsten-oxide film by oxygen deficiency and its mechanism

The transmissivity and the optical absorption of a WO₃ film with oxygen deficiencies introduced were characterized and compared with those of an electrochromically colored WO₃ upon injecting a proton (H⁺). The WO₃ film with oxygen deficiencies introduced was clearly colored blue. It was shown that the wavelength regions of optical absorption of both films almost overlapped each other.