Brain Amino Acids Measured by Intracerebral Dialysis in Portacaval Shunted Rats

Changes in brain amino acid uptake and metabolism have been proposed as a possible etiological factor in hepatic encephalopathy. By use of a brain dialysis technique (a thin tube implanted in the brain of the living animal), the extracellular amino acid concentrations in the striatum of portacaval (PC)-shunted and sham-operated rats were measured. Leucine, phenylalanine, methionine, and glutamine were increased two- to sixfold in the PC-shunted rats, whilst no changes were seen for GABA, valine, glutamate, or isoleucine, confirming previous reports. Aspartate levels were 350% higher in the PC-shunted rats, and this rise, as well as that of phenylalanine, was significantly correlated with the lower motor activity observed in the PC-shunted rats, suggesting a possible importance of these amino acids in the etiology of hepatic encephalopathy. The amino acid concentrations measured in whole blood demonstrated the well-known pattern of low levels of branched-chain amino acids and increased concentrations of phenylalanine, glutamine, and histidine.     

Transformation of cultured epithelial cells by ethylnitrosourea: Altered expression of type I procollagen chains

Cultured epithelial rodent cells were transformed in vitro using ethylnitrosourea as a carcinogen either alone or in combination with the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA). The frequency of transformation in the absence of TPA was 5·10^?4 at 10 μg/ml ethylnitrosourea. Growth of ethylnitrosourea-treated cells in TPA-substituted medium increased the transformation frequency 8-fold. Colonies of transformed cells were isolated from soft agar and analyzed for the production of pericellular matrix glycoproteins. The ethylnitrosourea-transformed cells retained pericellular matrix structures, typical of the nontransformed control cells. Parent cells produced into their culture media fibronectin and procollagen types I and III as their major pericellular glycoproteins. The ethylnitrosourea-transformed cells synthesized and secreted altered procollagen polypeptides. The procollagen of ethylnitrosourea-transformed cells apparently consisted mainly of homotrimeric proα1 molecules, with smaller amounts of basement membrane procollagen-like chains. Fibronectin synthesis or secretion was not affected by ethylnitrosourea-induced transformation, but the production of fibronectin was enhanced in the transformed cultures treated with TPA. Also, the deposition of procollagen and fibronectin into the pericellular matrix was not affected by ethylnitrosourea-transformation. Very similar changes had previously been observed in murine sarcoma virus-transformed cells. The change of procollagen type I thus appears to be a correlate of malignant transformation of cultured epithelial cells. The results indicate that ethylnitrosourea can induce malignant transformation of epithelial cells in culture and modify production and deposition of pericellular glycoproteins.     

Subcellular localization in normal and vitamin A-deficient rat liver of vitamin A serum transport proteins,albumin, ceruloplasmin and class I major histocompatibility antigens

The subcellular localization in rat liver cells of retinol-binding protein (RBP), prealbumin, ceruloplasmin, albumin, and class I transplantation antigen chains was investigated by radioimmunoassay determinations. The concentration of RBP was high in the rough and smooth endoplasmic reticulum (SER). The relative concentrations of prealbumin, ceruloplasmin and albumin were similar in the endoplasmic reticulum fractions and in the Golgi fraction. Neither of the proteins were found in significant amounts in the post-microsomal supernatant nor in the plasma membrane. The concentrations of the class I transplantation antigen chains were higher in the Golgi fraction than in the endoplasmic reticulum fractions. In the rough endoplasmic reticulum (RER) fraction ceruloplasmin and the class I antigens partially interact with high-molecular weight (MW) components, presumably membrane-bound glycosyltransferases. RBP, prealbumin and albumin seemed to be present in free form within the microsomal lumen. In vitamin A deficiency the RBP and to a lesser extent the prealbumin concentrations in the endoplasmic reticulum fractions were significantly increased, as compared to fractions from normal livers. This suggests that the presence of vitamin A is a prerequisite for the transport of RBP from the endoplasmic reticulum to the Golgi complex. The intracellular concentrations of albumin and ceruloplasmin were not significantly altered by vitamin A deficiency. In contrast, the amounts of the class I antigen heavy chains were found to be increased.     

Reconstitution of oxygen evolution in high salt washed photosystem II particles

Photosystem II thylakoid particles possessing high rates of oxygen evolution, were shown to have a very simple polypeptide composition. Upon washing of these particles with 250 mM NaCl the oxygen evolution was inhibited up to 80% concomitant with a release of two polypeptides of 23 and 16 kDa. Readdition of the pure 23 kDa protein to the depleted thylakoids under low ionic strength reconstituted more than half of the lost activity. No stimulation was obtained with the 16 kDa protein alone or in combination with glycerol. The results give further strong evidence that the 23 kDa protein is an essential component in the oxygen evolving complex. The possible involvement of other proteins in this complex is discussed in light of the demonstrated simple polypeptide pattern of the photosystem II particles.     

Synthesis of Escherichia coli outer membrane OmpA protein in yeasts

Saccharomyces cerevisiae was transformed with the Escherichia coli ompA gene coding for an outer membrane protein. Yeast transformants containing the pYTLJ101 plasmid, consisting of the ompA gene cloned in pSC101 and the HindIII-3 fragment of 2-μm DNA, express the foreign membrane protein. The protein synthesized in yeast has an M_r value very similar if not identical to that of the mature E. coli protein. The expressed protein is present in yeast mitochondrial and plasma membrane fractions. The yeast cell can tolerate about 250 molecules of the foreign membrane protein per cell, although the transformants show altered growth kinetics.     

Ammonium Production by Dissimilatory Nitrate Reducers Isolated from Baltic Sea Water, as Indicated by 15N Study

Bacteria able to perform dissimilatory nitrate reduction to ammonium were isolated from low-oxygen masses in the Baltic Sea. In liquid media enriched with ¹⁵NO₃⁻ and incubated anaerobically, the NH₄⁺-producing isolates transformed 25 to 72% of the ¹⁵NO₃⁻ to ¹⁵NH₄⁺.     

Functional Activity of Substantia Nigra Grafts Reinnervating the Striatum: Neurotransmitter Metabolism and [14C]2-Deoxy-d-glucose Autoradiography

Dopaminergic innervation of the caudate nucleus in adult rats can be partially restored by the grafting of embryonic substantia nigra into the overlying parietal cortex with concomitant compensation of certain behavioral abnormalities. In this study the function of such grafts was investigated neurochemically by quantification of transmitter metabolism and glucose utilization in the reinnervated target. Rats with unilateral 6-hydroxydopamine lesions of the nigrostriatal bundle received a single graft to the dorsal caudate-putamen and were screened for rotational behavior following 5 mg/kg methamphetamine. The grafts restored dopamine concentrations in the caudate-putamen from initially less than 0.5% to an average of 13.6% of normal in rats with behavioral compensation. The ratio of 3,4-dihydroxyphenylacetic acid to dopamine, which is a measure of the rate of transmitter turnover, were equivalent in transplanted and normal control rats. Moreover, measurements of DOPA accumulation for a 30-min period after DOPA decarboxylase inhibition indicated similar fractional dopamine turnover rates in normal and transplant-reinnervated tissues. Correlations between rotational behavior and dopamine concentrations showed that reinnervation to only 3% of normal was sufficient to counterbalance the motor asymmetry. Measurements of glucose utilization by [14C]deoxyglucose autoradiography indicated equivalent metabolic rates for the grafted tissue and the intact substantia nigra. 6-Hydroxydopamine denervation of the caudate-putamen had no significant effect on neuronal metabolism in that region, nor did subsequent reinnervation from a graft. Grafts, however, were associated with a 16% reduction of glucose uptake in the ipsilateral globus pallidus, indicating a significant transsynaptic influence of the nigral transplants on neuronal metabolism in the host brain. Overall the results indicate that behaviorally functional neuronal grafts spontaneously metabolize dopamine and utilize glucose at rates characteristic of the intact nigrostriatal system. This provides further evidence that ectopic intracortical nigral transplants can reinstate dopaminergic neurotransmission in regions of the host brain initially denervated by the 6-hydroxydopamine lesion.     

Plasmids in Methylomonas clara,a methylotrophic producer of single cell protein

Summary Three single cell clones of the obligate methylotrophic bacterium Methylomonas clara originating from one fermentor culture were assayed for their DNA content. Apart from chromosomal DNA which showed no difference in the three strains, only two strains were found to carry plasmids with identical buoyant density and GC content but differing in contour length (12.4 m and 4.9 m respectively). According to their restriction pattern they are derived from each other. Both plasmids are not involved in methanol metabolism, since the third strain was found to be devoid of plasmids. The possibility of using these plasmids to establish vectors for gene cloning is evident, since during prolonged vegetative growth the specific plasmid content remains constant.     

Proteinase activity in macrophage cultures. Effects of heparin and antithrombin

Mouse macrophages in vitro secrete an esterase capable of hydrolysing the chromogenic peptide substrate S-2222. The enzyme activity is inhibited by antithrombin and heparin. Also, the cells produce other hydrolytic activity, mainly associated with the cells capable of decomposing S-2160 and resistant to antithrombin and heparin.     

The genus Calceolaria in NW South America VIII. The section Calceolaria and appendices to parts I–VIII

Sect. Calceolaria (= Aposecos) of Calceolaria (Scrophulariaceae) in NW South America is revised, and the other species of the section are briefly discussed. The section comprises annual herbs with somewhat succulent stems and leaf–blades that are usually pinnately dissected (pinnatifid). Four species are recognized in the investigated area, viz. C. mexicana, C. tenuis, C. tripartita , and C. chelidonioides , and their chromosome numbers are reported (2n = 32, 60, 64, and 60 respectively). The basic number in sect. Calceolaria is x = 8. Two new combinations are made, viz. C. mexicana ssp. prostrata (Kränzlin) Molau and C. mexicana ssp. perijensis (Pennell) Molau. The species of sect. Calceolaria are intersterile and facultatively autogamous, and each species comprises numerous pure lines, some of which may be morphologically discernible.
In the appendices, chromosome numbers are listed and the occurrence of elaiophores in all NW South American species of Calceolaria is indicated. The chromosome numbers of C. crenata ssp. australis, C. adenanthera, C. gossypina, C. semiconnata, C. stricta, C. sericea , and C. comosa (all 2n = 36) have not previously been reported. A revised key to the sections of Calceolaria in NW South America is also provided.