Localization of GABA-like immunoreactivity in the ectostriatum of domestic chicks: GABA immunocytochemistry combined with Golgi impregnation

Brain Cell Biology - The distribution of GABA-like immunoreactivity (GABA-LI) in the ectostriatal core (Ec) of domestic chicks (one to two days old) was investigated using (1) preembedding GABA...     

Novel inhibitors of enkephalin-degrading enzymes. II: N5'-substituted-4-thioxohydantoic acids as aminopeptidase inhibitors

Some 2-substituted-(2'-aminophenyl)-4-thioxohydantoic acids (o-amino PTC-amino acids) have antinociceptive activity when administered (icv) alone (IC50 = 0.04-0.87 microM/animal) and show a striking prolongation of the antinociceptive action of (D-Ala-2 D-Leu5)-enkephalin (DADL) in combination. The effects are thought to be mediated via opioid receptors since they are naloxone-reversible. Although inhibitors of the enkephalin degrading puromycin-insensitive, bestatin-sensitive aminopeptidase (possibly aminopeptidase M) their action is weak (IC50 = 32 microM leucine, 536 microM, glycine) and they might be considered to have a direct antinociceptive effect on opioid receptors. The titled compounds constitute novel 'lead' compounds for the development of potent aminopeptidase M inhibitors.     

Novel inhibitors of enkephalin-degrading enzymes. III: 4-Carboxymethylamino-4-oxo-3 (phenylamino) butanoic acids as enkephalinase inhibitors.

4-Carboxymethylamino-4-oxo-3-(4'-aminophenylamino) butanoic acid (25), its ethyl ester (26) and the corresponding unsubstituted-aryl analogues (17) and (16) are fairly potent inhibitors of enkephalinase (neutral endopeptidase; EC 3.4.24.11), Ki = 0.14-0.39 microM, with weak inhibitory potency, Ki = 15-75 microM, towards aminopeptidase MII. In the mouse abdominal constriction test, the esters (26) and (16) showed systemic inhibitory (antinociceptive) activity with ED50 values 62 +/- 3.05 and 81 +/- 1.74 mg/kg respectively. In the mouse tail immersion test, both (26) and (16) exhibited antinociceptive activity when administered intracerebroventricularly and (26) also exhibited a systemic effect which was only partially reversed by naltrexone. The antinociceptive effect seen with (26) reflects its ranking in vitro as an inhibitor of enkephalinase (Ki = 0.14 microM) but it is possible that this effect is not totally opioid-mediated. Compounds (26) and (16) represent the first combined inhibitors of enkephalinase and aminopeptidase MII.     

Lineage, migration, and morphogenesis of longitudinal glia in the Drosophila CNS as revealed by a molecular lineage marker

Previous studies described three different classes of glial cells in the developing CNS of the early Drosophila embryo that prefigure and ensheath the major CNS axon tracts. Among these are 6 longitudinal glial cells on each side of each segment that overlie the longitudinal axon tracts. Here we use transformant lines carrying a P element containing a 130 bp sequence from the fushi tarazu gene in front of the lacZ reporter gene to direct beta-galactosidase expression in the longitudinal glia. Using this molecular lineage marker, we show that 1 of the "neuroblasts" in each hemisegment is actually a glioblast, which divides once symmetrically, in contrast to the typical asymmetric neuroblast divisions, producing 2 glial cells, which migrate medially and divide to generate the 6 longitudinal glial cells. As with neuroblasts, mutations in Notch and other neurogenic genes lead to supernumerary glioblasts. The results indicate that the glioblast is similar to other neuroblasts; however, the positionally specified fate of this blast cell is to generate a specific lineage of glia rather than a specific family of neurons.     

Production by K 562 cells of an inhibitor of adherence-related functions of human neutrophils

Certain tumor cells generate factors that inhibit neutrophil chemotaxis. Our study was designed to explore whether such factors are produced by K 562 malignant cells and whether these have a broader effect in altering neutrophil functions. After 48 h of in vitro culture of K 562 cells, the culture medium and the cells were separated, lyophilized, and extracted with ethanol. These K 562 products, i.e., either the cell or supernatant extract, inhibited both nonstimulated locomotion and locomotion induced either by FMLP or activated serum. Furthermore, K 562 products inhibited neutrophil adherence and oxidative burst induced by opsonized zymosan, whereas oxidative burst induced by PMA or FMLP was not altered. K 562 products had an inhibitory effect on the PMN binding to iC3b-coated particles. They did not modify Mo1 expression of resting cells, did not alter the up-regulation of the receptor induced by FMLP but inhibited the FMLP-induced capping of Mo1 Ag. Con A capping was also inhibited. Actin polymerization in FMLP-stimulated PMN, as measured by flow cytometry and phalloidin binding to F-actin, was inhibited by K 562 products. The inhibitory factor present in K 562 products (cell and culture supernatant) was purified in three steps including gel filtration, ion-exchange chromatography, and IEF. The eluted active fraction corresponded to single band of about 8 kDa on SDS-PAGE. From these experiments, it is concluded that K 562 malignant cells in culture contain and release a low molecular mass factor (congruent to 8 kDa) that inhibits all adherence-related functions of neutrophils, whereas it does not alter FMLP- or PMA-induced oxidative burst. Further studies are needed to assess whether products of other tumor cells also act on the neutrophil by inhibiting adherence-related functions, Mo1 function and capping, and actin polymerization.     

Expression and biochemical characterization of human immunodeficiency virus type 1 nef gene product.

nef genes from human immunodeficiency virus type 1 isolates BH10 and LAV1 (lymphadenopathy-associated virus type 1) were expressed in Escherichia coli under the deo operon promoter. The two proteins found in the soluble compartment of the bacterial lysate were purified by ion-exchange column chromatography to apparent homogeneity. Determination of the amino-terminal sequence revealed glycine as the first amino acid in the Nef protein, indicating removal of the initiator methionine during expression in E. coli. Under native conditions, the recombinant Nef protein is a monomer of 23 kilodaltons. In denaturing polyacrylamide gels, however, BH10 and LAV1 Nef proteins migrate as 28 and 26 kilodaltons, respectively. GTP binding and GTPase activity were monitored during Nef protein purification. These activities did not copurify with the recombinant Nef protein from either the BH10 or the LAV1 isolate. Purified recombinant BH10 Nef protein was used as an immunogen to elicit mouse monoclonal antibodies. A series of monoclonal antibodies were obtained which reacted with sequences at either the amino or carboxy terminus of Nef. In addition, a conformational epitope reacting with native BH10, but not LAV1, Nef was isolated.     

Structures of minor ether lipids isolated from the aceticlastic methanogen, Methanothrix concilii GP6

Structures were determined for two phospholipids and three glycolipids purified from chloroform-methanol extracts of Methanothrix concilii GP6. Together they accounted for 14% of the total lipid and were based on a C20,20-diether core structure consisting of either 2,3-di-O-phytanyl-sn-glycerol or its 3'-hydroxy analog, namely, 2-O-[3,7,11,15-tetramethylhexadecyl]-3-O-[3'- hydroxy-3',7',11',15'-tetramethylhexadecyl]-sn-glycerol. These two core lipids formed phosphodiester bonds to ethanolamine and glycosidic bonds to beta-D-galactopyranose. A third glycolipid consisted of the triglycosyl head group beta-D-galactopyranosyl-(1----6)-[beta-D-glucopyranosyl-(1----3)]-beta-D - galactopyranose in glycosidic linkage to the 3'-hydroxydiether core lipid.