Nearest-neighbor and next-nearest-neighbor effects in the proton NMR spectra of the oligoribonucleotides ApGpX and CpApX

The variable-temperature proton nmr spectra of the oligoribonucleotides in the series CpApX and the series ApGpX, X = A, G, C, U, together with the parent dimers CpA and ApG have been measured. A complete analysis of all the nonexchangeable base proton resonances and ribose H-1′ proton resonances was made. The presence of trends in the shielding abilities of the various bases at both the nearest-neighbor and next-nearest-neighbor positions were identified. The observed shieldings could be used to predict the chemical shifts of protons in related systems. Based on the empirical results from ribodinucleoside monophosphates, the temperature-dependent behavior of the J_1′2′ coupling constants of the triribonucleotides suggested that the compounds in the CpApX series stacked from the 5′-end to the 3′-end, while those in the ApGpX series stacked from the 3′-end to the 5′-end.     

The evolution of conspicuous coloration: Some experiments in bad taste

Unpalatable species are often brightly coloured. Such aposematic coloration may have evolved because predators can learn to avoid conspicuous prey more readily than cryptic prey. Experiments on young male chicks are described and the results are consistent with this hypothesis.     

Dynamic organization of mitochondrial membranes: A crosslinking study with dimethylsuberimidate

Rat liver mitochondria were treated with dimethylsuberimidate, a bifunctional alkylating agent, and the effects were evaluated kinetically. Concurrently with the modification of amino groups, mitochondrial proteins were crosslinked and the organelles lost their osmotic response. When the dimethylsuberimidate reaction was performed in the presence of succinate, more primary amino groups were available when compared with a sucrose medium. Concomitantly, osmotic stabilization and crosslinking of mitochondrial proteins were accelerated. The activity of aspartate aminotransferase was also studied in crosslinked mitochondria. The enzyme activity was only slightly modified when mitochondria were amidinated in a sucrose medium and solubilized thereafter with Triton X-100 or cetyltrimethylammonium bromide. In contrast, in the presence of succinate, 60% of activity was lost after solubilization with Triton X-100, but not after solubilization with cetyltrimethylammonium bromide. This finding was correlated with the changes in intramitochondrial localization of the enzyme (A. Waksman and A. Rendon, 1974,Biochimie54, 907–924). When carbonylcyanide-p-trifluoromethoxyphenylhydrazone was added in both cases (sucrose or sucrose plus succinate), the rates of osmotic stabilization, amidination reaction, crosslinking of proteins, and aspartate aminotransferase activity were similar to those observed in a sucrose medium alone. The present results suggest that organizational changes of the mitochondrial membranes induced by succinate, including intramitochondrial protein movement, are prevented by carbonylcyanide-p-trifluoromethoxyphenylhydrazone.     

Immunochemical studies on the combining site of the d-galactopyranose and 2-acetamido-2-deoxy-d-galactopyranose specific lectin isolated from Bauhinia purpurea alba seeds

The combining site of the Bauhinia purpurea alba lectin was studied by quantitative precipitin and precipitin inhibition assays. Of 45 blood group substances, glycoproteins, and polysaccharides tested, 35 precipitated over 75% of the lectin. Precursor blood group substances with I activity (Cyst OG 10% from 20% and Cyst OG 20% from 10%), desialized fetuin, and desialized ovine salivary glycoprotein, in which more than 75% of the carbohydrate side chains have dGalN Ac linked through α1 → to the OH group of Ser or Thr of a protein core, completely precipitated the lectin. The poorly reactive blood group substances after mild acid hydrolysis or Smith degradation, as well as sialic acid-containing glycoproteins after removal of sialic acid, had substantially increased activity so that more than 80% of the lectin was precipitated. Precipitability with various blood group substances and glycoproteins is ascribable to the terminal nonreducing dGalNAc, dGalβ1 → 3dGalNAc, dGalβ1 → 3 or 4dGlcNAc, and dGalβ1 → 3 or 4dGlcNAcβ1 → 3dGal determinants on the carbohydrate moiety. Of the monosaccharides tested for inhibition of precipitation, dGalNAc and its p-nitrophenyl and methyl α-glycosides were best. These compounds were four to five times better than the corresponding dGal compounds but methyl βDGalNAcp was only about 40% more active than methyl βdGalp. The α-anomers of p-nitrophenyl DGalNAcp and dGalp, were twice as active as the corresponding β-anomers. Methyl αDGalNAcp was four times as active as the β-anomer but the inhibitory power of the methyl α- and β-anomers of dGal were about equal. Among the oligosaccharides tested, dGalβ1 → 3dGalNAc and its tosyl derivatives were most active, the tosyl glycosides being about twice as active as dGalβ1 → 3dGalNAc, which was somewhat more active than dGalNAcα1 → 6dGal and dGalNAc, and 2.5 and 5 times as active as dGalNAcα1 → 3dGalβ1 → 3dGlcNAc and dGalNAcαl → 3dGa1, respectively (blood group A specific). These findings suggest that a subterminal dGalNAc β-linked and substituted on carbon 3 plays an important role in binding. Consistent with this inference are the findings that dGalβ1 → 3dGlcNAc and dGalβ1 → 6dGal were poorer inhibitors although dGalβ1 → 3dGlcNAc was two to three times as active as glycosides of dGal. Oligosaccharides with terminal nonreducing dGal and subterminal α-linked dGal were as active or less active than dGal. dGalβ1 → 3dGlcNAcβ1 → 3dGalβ1 → 4dGlc (lacto-N-tetraose) and dGalβ1 → 3dGlcNAcβ1 → 3dGal-β1-O-(CH₂)₈COOCH₃ were equally active and 1.5 times as potent as dGalβ1 → 3dGlcNAc whereas dGalβ1 → 3dGlcNAcβ1 → 6dGal was only 40% as potent as dGalβ1 → 3dGlcNAc suggesting that a third sugar may be part of the determinant. Substitution of dGalβ1 → 3dGlcNAcβ1 → 3dGalβ1 → 4dGlc on the subterminal dGlcNAc by lFucα1 → 4 in lacto-N-fucopentaose II reduced activity fourfold; if the nonreducing dGal is substituted by lFucα1 → 3 as in lacto-N-fucopentaose I its activity is almost completely abolished. This suggests that a terminal nonreducing dGal as well as subterminal dGlcNAc are contributing to binding. The β → 3 linkage of the terminal dGal to the subterminal amino sugar is significant since dGalβ1 → 4dGlcNAc is a poorer inhibitor. Although the available data suggest that the combining site of the lectin Bauhinia purpurea alba may be most complementary to the structure dGalβ1 → 3dGalNAcβ1 → 3dGal, several other possibilities remain to be tested when suitable oligosaccharides become available.     

Comparison of phospho- and dephospho-ATP citrate lyase

The dephospho- form of rat liver citrate lyase has been prepared by treating purified [³²P]-ATP citrate lyase with a partially purified phosphatase. A comparison of the properties of the phospho- and dephosphoenzyme has been performed. The pH optima were the same for both forms of the enzyme in four different buffer systems although the optimum values varied identically for both enzyme forms with the buffer. Both the phospho- and dephosphoenzymes show the same kinetic properties except for the K_m observed for ATP in 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid buffer system where it was 54 μm for the phosphoenzyme and 292 μm for the dephosphoenzyme. The present study also indicates that both enzymes are cleaved by trypsin and lysosomal proteases in a similar manner. Both forms of the enzyme tend to associate with mitochondria to the same extent and both enzymes have identical temperature stability curves.     

Comparison by Elisa of serum anti-Candida albicans mannan IgG levels of a normal population and in diseased patients

Quantitative and qualitative studies were made of the fungi of the air in Barcelona City. The genera Cladosporium and Alternaria formed two of the most important components of the fungus population studied during a two-year period running from January 1976 through January 1978. Penicillium species formed the 16.3 % of the total colonies while Aspergillus species represented only the 2.8 %. The occurrence of these genera was greatly affected by climatic conditions. An attempt was made to summariza the data of various kinds of fungi on a volumetric basis. Most of the fungi reported here have been identified as far as genera.

---

Résumé Une étude qualitative ainsi que quantitative a été réalisée sur la population fongique présente dans l'atmosphère de la ville de Barcelone. Les genres Cladosporium et Alternaria constituent les moisissures les plus inportantes quant à leur présence parmis la population fongique étudiée durant la période de deux ans comprise entre le mois de Janvier 1976 et le mois de Janvier 1978. Le genre Pénicillium représentait le 16.3% de la totalité des colonies isolées, tandis que le genre Aspergillus ne représentait que le 2.8%. La présence d'espéces de ces genres était largement influencée par les conditions climatologiques. Les données sur la présence des différents genres de moisissures ont été établies sur une base volumétrique. La plupart des moisissures identifiables l'ont été jusqu'au genre.

     

Studies on formation and resorption of fish scales

Summary Scale formation in Cyprinodon variegatus was found to be initiated at about 26 to 30 days after hatching. Ultrastructural investigation revealed that within 4 to 6 h in the first-formed scales the marginal cells begin to flatten and differentiate into osteogenic cells, which later change to osteoblasts and fibroblasts. These cells are separated from the surrounding epithelial cells by a basal lamina. The osteoid is formed by the marginal and osteogenic cells; the osseous layer by the osteoblasts; and the fibrillary plate by the fibroblasts.The osteoid is formed within 2 to 3 h after the initiation of the scale, and within 20 to 24 h the osseous layer is formed. Hydroxyapatite crystals are deposited in the matrix of the osseous layer without apparent association with collagen fibers. No matrix vesicles or dense bodies are evident at the sites of calcification. The fibrillary plate arises 18 to 20 h after the initiation of the scale. It is also partially calcified, but not before the third week of scale formation. The crystals develop almost exclusively between the collagen fibers at the extreme edge of the calcifying front, but solid calcification of the fibers results with further growth of the crystals. The fibroblasts appear to participate in calcification of the fibrillary plate.Contribution No. 332, Belle W. Baruch Institute for Marine Biology and Coastal Research, University of South Carolina, Columbia, South Carolina, 29208, USA     

[1251]2α-BUNGAROTOXIN AND [3H]QUINUCLIDINYLBENZILATE BINDING IN CENTRAL NERVOUS SYSTEMS OF DIFFERENT SPECIES

Abstract— [¹²⁵I]Diiodo α-bungarotoxin ([¹²⁵I]₂BuTx) and [³H]quinuclidinylbenzilate ([³H]QNB) binding sites were measured in post-nuclear membrane fractions prepared from whole brains or brain regions of several species. Species studied included Drosophila melanogaster (fruit fly), Torpedo californiea (electric ray), Carassius auratus (goldfish), Ram pipiens (grass frog), Kana cutesheiana (bullfrog), Rattus norvegicus (rat, Sprague-Dawley), Mus muscalus (mouse, Swiss random, C58/J, LG/J), Oryctolagus cuniculus (rabbit, New Zealand Whitc), and Bos (cow). Acetyl-CoA: choline O -acetyltransferase (EC 2.3.1.6) levels were also determined in the post nuclear supernatants and correlated with the number of binding sites.
All species and regions except Drosophila had 16–150 fold more [³H]QNB binding sites than [¹²⁵I]₂BuTx binding sites. Brain regions with the highest levels of [¹²⁵I]₂BuTx binding were Drosophila heads (300 fmol/mg), goldfish optic tectum (80fmol/mg), and rat and mouse hippocampus (3040 fmol/mg). The highest levels of [³H]QNB binding were seen in rat and mouse caudate (1.3–1.6 pmol/mg). Lowest levels of [³H]QNB and [¹²⁵I]₂BuTx binding were seen in cerebellum. The utility of [¹²⁵I]₂BuTx and [³H]QNB binding as quantitative measures of nicotinic and muscarinic acetylcholine receptors in CNS is discussed.     

BRAIN TISSUE AND PLASMA ASSAY OF L-DOPA AND α-METHYLDOPA METABOLITES BY HIGH PERFORMANCE LIQUID CHROMATOGRAPHY WITH ELECTROCHEMICAL DETECTION

Using reverse phase high-performance liquid chromatography and electrochemical detection with mobile phases composed of simple acids, we have developed an assay technique to measure multiple catecholamines and their catechol metabolites in plasma or brain tissue with sensitivity to the picomole level. Ion-pairing chromatography with nitric or trichloroacetic acid as the mobile phase permits separation and quantitation of norepinephrine, α-methylnorepinephrine, epinephrine, dopamine, α-methyldopamine, l -DOPA, α-methyldopa, carbidopa, and DOPAC. Alumina extraction selectively isolates catechols which are then separated on a reverse-phase column and measured by a commercially available electrochemical detector. This method has been applied to measurement of L-DOPA metabolites in patients with Parkinson's disease treated with L-DOPA and carbidopa and to measurement of catecholamines in rat hypothalamus in the course of studies on L-DOPA and α-methyldopa metabolism. Dihydroxybenzylamine is added as an internal standard and standard curves are linear over two orders of magnitude in concentration with coefficients of variation averaging 3.1%. Quantitation is routinely done to 20 pmol with absolute sensitivity possible to 0.5 pmol.     

PURIFICATION FROM HUMAN BRAIN AND SOME PROPERTIES OF TWO NADPH-LINKED ALDEHYDE REDUCTASES WHICH REDUCE SUCCINIC SEMIALDEHYDE TO 4-HYDROXYBUTYRATE

Abstract— Two NADPH-linked aldehyde reductases (alcohol:NADP⁺oxidoreductase, EC 1.1.1.2) capable of reducing succinic semialdehyde to the anaesthetic Chydroxybutyrate have been purified from human brain to electrophoretic homogeneity. The first of these enzymes, which is typical of its category, is not specific for succinic semialdehyde and can reduce some aromatic aldehydes at a high rate. It is a monomer of molecular weight about 45,000 and is strongly inhibited by various hypnotics and anticonvulsants. The second enzyme is, in contrast, fairly specific for succinic semialdehyde. It is a dimer of molecular weight about 90,000 and is not inhibited by the hypnotics and anticonvulsants which inhibit the first enzyme. It is thus different from previously described aldehyde reductases from human brain.