DARPP-32 and Phosphatase Inhibitor-1, Two Structurally Related Inhibitors of Protein Phosphatase-1, Are Both Present in Striatonigral Neurons

DARPP-32 (dopamine- and cyclic AMP-regulated phosphoprotein of Mr = 32,000) and phosphatase inhibitor-1, two previously characterized inhibitors of protein phosphatase-1, were identified in both the neostriatum and the substantia nigra. Phosphatase inhibitor-1 was partially purified from bovine caudate nucleus and found to be distinct from DARPP-32 in some of its biochemical properties. The neuronal localization of DARPP-32 and phosphatase inhibitor-1 within the rat neostriatum and substantia nigra was investigated by studying the effects of kainic acid. Injection into the neostriatum of kainic acid, which destroys striatonigral neurons and striatonigral fibers, decreased the amounts of DARPP-32 and phosphatase inhibitor-1 to the same extent, both in the lesioned neostriatum and in the ipsilateral substantia nigra. The specific activity of protein phosphatase-1 in the neostriatum was unaffected by kainic acid. The results indicate that, in rat brain, DARPP-32 and phosphatase inhibitor-1 are both present in striatal neurons and in striatonigral fibers, and that they probably coexist in at least a subpopulation of striatonigral neurons. In contrast, protein phosphatase-1 does not appear to be enriched in any specific neuronal subpopulation in the neostriatum.     

Analyses of ribosomal proteins from mycobacteria with particular reference to the β antigen

Abstract The proteins of the ribosomal subunits of Mycobacterium phlei were analysed by sodium dodecylsulphate (SDS)-polyacrylamide gel electrophoresis (PAGE) and by 2-dimensional PAGE. These techniques revealed that both the size and the charge of the mycobacterial ribosomal proteins were quite different from those of Escherichia coli . The divergent chemical properties of the mycobacterial ribosomes might be related to other exceptional properties of mycobacteria, e.g., their slow growth. An antigen designated β was furthermore revealed in both 30S and 50S subunits of M. phlei and Mycobacterium bovis BCG. 2 Proteins from each subunit migrated in a similar way in SDS-PAGE, being thus prime candidates as carriers of β-activity.     

Protochlorophyllide transformations and chlorophyll accumulation in epicotyls of pea (Pisum sativum)

Low-temperature fluorescence emission spectra of epicotyls of 6.5-day-old dark-grown seedlings of pea ( Pisum sativum L.) showed the dominance of short-wavelength protoch lorophyllide forms with emission maxima at 629 and 636 nm, respectively. The presence of long-wavelength protochlorophyllide with emission maxima around 650 nm was just detectable. Accordingly, irradiation with millisecond flashes gave a minute formation of chlorophyllide. The chlorophyll(ide) formation varied along the epicotyl. Irradiation with continuous light for 1.5 h resulted in an evident accumulation of chlorophyll(ide) in the upper part of the epicotyl. Only small amounts accumulated in the middle section. The conversion of protochlorophyllide to chlorophyllide was temperature dependent and almost arrested at 0°C. The chlorophyll(ide) formed had one dominating fluorescence peak at 681 nm. Irradiation for 24 h gave almost 100 times more chlorophyll in the upper part of the epicotyl than in the lower part. Electron micrographs from the upper part of the epicotyl irradiated for 6 h showed plastids with several developing thylakoids, while the plastids in the lower part of the epicotyl had only a few thylakoids. The dominance of short-wavelength protochlorophyllide forms indicated the presence of protochlorophyllide not bound to the active site of NADPH-protochlorophyllide oxidoreductase (EC 1.3.1.33). The inability of the short-wavelength form to transform into chlorophyllide with flash light denotes a dislocation from the active site. The time and temperature dependence of the chlorophyll(ide) formation in continuous light indicates that a relocation is required of the short-wavelength protochlorophyllide before chlorophyllide formation can occur.     

Gas exchange pattern in the two‐spot ladybird beetle,Adalia bipunctata,differs in dry vs. moist air

Gas exchange patterns in the ladybird beetle, Adalia bipunctata (L.) (Coleoptera: Coccinellidae), were investigated using an infrared gaseous analyser (IRGA) and a coulometric O₂ respirometer (manometric–volumetric system). Before testing, the beetles were kept either in dry (dehydrated) or moist (hydrated) conditions for 1 day. Their subsequent gas exchange patterns did not depend on their state of humidity but rather were controlled by the humidity of the insect chamber during gas exchange measurement. If this chamber contained dry air, the beetles exhibited CO₂ release by burst, which we interpreted as cyclic gas exchange (CGE) with inter‐burst periods, but if the chamber was switched to contain moist air, then cyclic CO₂ release was soon abandoned and a pattern of continuous gas exchange appeared. Measurements with the coulometric respirometer in moist air showed that continuous gas exchange was often associated with weak abdominal pulsations, which we interpreted as active ventilation. Their metabolic rate was lower during gas exchange cycles than during continuous gas exchange. We revealed that in the ladybird beetle metabolic rate increased in moist air when the gas exchange pattern transitioned from cyclic to continuous.     

MCR III1. Multicomponent Reactions and Their Libraries,a New Type of Organic Chemistry of the Isocyanides and Phosphorus Derivatives.

Abstract

Various new one-pot multicomponent reactions (MCRs) of C^II and P^III derivatives and their libraries are described here. The preparation of some nucleobase- and phospholipid compound libraries by MCRs have been carried out.

     

Cell–Substrate Contact: Another Factor May Influence Transepithelial Electrical Resistance of Cell Layers Cultured on Permeable Filters

Transepithelial resistance (TER) measurement has often been used to study the paracellular transport properties of epithelia grown on permeable filters, especially the barrier function of tight junctions. However, the TER value includes another source, the resistance caused by cell–substrate contact, that may give rise to a high TER value if cell–substrate separation is small. In this study we use electric cell–substrate impedance sensing (ECIS) to measure both paracellular resistance and the average cell–substrate distance of MDCK (II), HEp-2, and WI-38 VA13 cells. Comparing ECIS data with those from TER measurements of cell layers cultured on polycarbonate filters, we can obtain the approximate extra resistance resulting from cell–substrate contact for each cell type. The value of cell–substrate resistance was also estimated by two theoretical calculations that bracket the true values. Our results demonstrate that cell–substrate contact substantially influences the TER data measured using polycarbonate filters and that the extra resistance due to cell–substrate spaces depends on both cell type and filter property.