Identification of a set of genes showing regionally enriched expression in the mouse brain

Background

We have recorded responses from single neurons in murine visual cortex to determine the effectiveness of the input from the two murine cone photoreceptor mechanisms and whether there is any unique selectivity for cone inputs at this higher region of the visual system that would support the possibility of colour vision in mice. Each eye was stimulated by diffuse light, either 370 (strong stimulus for the ultra-violet (UV) cone opsin) or 505 nm (exclusively stimulating the middle wavelength sensitive (M) cone opsin), obtained from light emitting diodes (LEDs) in the presence of a strong adapting light that suppressed the responses of rods.

Results

Single cells responded to these diffuse stimuli in all areas of striate cortex. Two types of responsive cells were encountered. One type (135/323 – 42%) had little to no spontaneous activity and responded at either the on and/or the off phase of the light stimulus with a few impulses often of relatively large amplitude. A second type (166/323 – 51%) had spontaneous activity and responded tonically to light stimuli with impulses often of small amplitude. Most of the cells responded similarly to both spectral stimuli. A few (18/323 – 6%) responded strongly or exclusively to one or the other spectral stimulus and rarely in a spectrally opponent manner.

Conclusion

Most cells in murine striate cortex receive excitatory inputs from both UV- and M-cones. A small fraction shows either strong selectivity for one or the other cone mechanism and occasionally cone opponent responses. Cells that could underlie chromatic contrast detection are present but extremely rare in murine striate cortex.     

The photochemistry of α-aryl carboxylic anhydrides—II : Photolysis of some substituted phenylacetic anhydrides

The photolysis of phenylacetic acids and anhydrides with λ 254 nm was studied. The main product is bibenzyl, but with o- and p-methoxyphenylacetic anhydride, in addition substantial amounts of methoxybenzyl methoxyphenylacetates are formed. The photoreactivity of phenylacetic acid strongly reduces upon substitution of the phenyl ring, this in contrast to the behaviour of the corresponding anhydrides. The quantum yields for substrate conversion and product formation are reported. The mechanisms of the photo-formation of the products are discussed. Experimental evidence is presented to support the proposition that the ester formation occurs via a dipolar intermediate.     

Crystal growth of Ln3GaO6 (Ln = Nd, Sm, Eu and Gd): Structural and optical properties

Single crystals of Ln₃GaO₆ (Ln = Nd, Sm, Eu, Gd) were grown out of a reactive high temperature hydroxide melt. The structures were solved by single-crystal X-ray diffraction. These gallium oxides crystallize in the polar space group Cmc2₁ where the orientation of the GaO₄ tetrahedra determines the polarity of the structure. The atomic positions along with the determination of the absolute structure are reported. The lanthanide atoms are located in a seven-fold coordination environment forming edge-sharing zigzag-chains. The photoluminescence was investigated and the europium and gadolinium members of this series exhibit intense luminescence in the visible portion of the spectrum.     

Synthesis of Retro-γ-Ionols and the Corresponding-Ionones1

Both the direct² and the sensitized^3,4 photolyses of (E)-β-ionol (2) have been studied in some detail. In a preliminary publication⁵ we have indicated that direct photolyses of (E)-β-ionol (2) with λ = 254 nm yields (Z)-retro-γ-ionol (3) as the primary product; upon further irradiation 3 is converted into the corresponding (E)-isomer (4) which rapidly yields the bicyclic alcohol 5. A quantitative study revealed that the photoconversion of (E)-β-ionol with λ = 254 nm to 3 is about 10 times faster than the conversion of 3 into (E)-retro-γ-ionol.⁶ This rate difference thus allows the photosynthesis of 3.     

Pirlimycin residue in bovine liver--a case of reverse metabolism.

Samples of liver obtained from twenty dairy cows treated with pirlimycin hydrochloride (Pirsue) by the intramammary route and slaughtered at five different time intervals out to 28 days were incubated at room temperature and at 37 degrees C and analyzed by two HPLC-MS methods to examine the metabolite profile of the residue and to establish the quantitative relationship of the residue components. The evidence from these experiments suggests that the metabolism of pirlimycin in postmortem bovine liver is somewhat reversible, where the concentration of parent pirlimycin increases in the incubated liver with a concomitant reduction in the concentration of the pirlimycin sulfoxide metabolite. This increased parent-drug residue phenomenon is limited to liver and was not observed in kidney or muscle. The highest relative change in concentration was observed for low level biologically incurred samples and appeared to be a saturable process following Michaelis-Menten kinetics. All of the evidence collected appears to indicate that the phenomenon is the result of residual enzyme activity present in the postmortem liver samples and likely involves some type of reductase enzyme capable of reducing sulfur-oxidized substrates to the sulfide state. No attempts were made to identify specific enzymes responsible for this phenomenon.