Prediction of sequential antigenic regions in proteins

Prediction of antigenic regions in a protein will be helpful for a rational approach to the synthesis of peptides which may elicit antibodies reactive with the intact protein. Earlier methods are based on the assumption that antigenic regions are primarily hydrophilic regions at the surface of the protein molecule. The method presented here is based on the amino acid composition of known antigenic regions in 20 proteins which is compared with that of 314 proteins [(1978) Atlas of Protein Sequence and Structure, vol. 5, suppl. 3, 363-373]. Antigenicity values were derived from the differences between the two data sets. The method was applied to bovine ribonuclease, the B-subunit of cholera toxin and herpes simplex virus type 1 glycoprotein D. There was a good correlation between the predicted regions and previously determined antigenic regions.     

Two new species of coccidia (Apicomplexa: Eimeriidae) from Madagascar Gekkonids

Two new species of coccidia (Apicomplexa: Eimeriidae) are described from the Madagascar giant day gecko, Phelsuma madagascariensis grandis, and the Golddust day gecko, P. laticauda. Both species of coccidia were found to infect the anterior one-half of the small intestine. Oocysts of Eimeria brygooi n. sp. are spherical or subspherical, 23.0 X 21.3 (18.8-25.2 X 16.4-23.2)micron; shape index (L/W) 1.1 (1.0-1.2). A micropyle, oocyst residuum, and polar granule are absent. Sporocysts are ovoid, 9.2 X 7.9 (8.0-10.0 X 7.2-8.8) micron; shape index 1.2 (1.0-1.3), with a Goussia-type suture; Stieda and substieda bodies are absent. A sporocyst residuum is present, 4.2 X 3.0 (3.2-6.4 X 2.4-4.0) micron. Sporozoites are elongate, with anterior and posterior refractile bodies. This coccidian was found to infect five of six (83%) P. m. grandis and one of five (20%) P. laticauda examined. Oocysts of Isospora gekkonis n. sp. are spherical or subspherical, 24.2 X 22.0 (21.6-26.4 X 20.0-23.6) micron; shape index 1.1 (1.0-1.2). A micropyle and oocyst residuum are absent; polar granule present. Sporocysts are ovoid, 12.2 X 9.4 (11.2-12.8 X 8.4-10.0) micron, with Stieda and substieda bodies; shape index 1.3 (1.2-1.4). A sporocyst residuum is present, either compact, 5.1 X 4.2 (4.0-7.2 X 3.2-5.6) micron or diffuse. Sporozoites are elongate, with anterior and posterior refractile bodies. Isospora gekkonis was found in two of six (33%) P. m. grandis and one of five (20%) P. laticauda. In addition, oocysts of Cryptosporidium sp. were found in the cloacas of two of six (33%) necropsied P. m. grandis.     

Mapping and sequencing of a gene from myxoma virus that is related to those encoding epidermal growth factor and transforming growth factor alpha.

Myxoma virus, a Leporipoxvirus and agent of myxomatosis, was shown to possess a gene with the potential to encode an epidermal growth factorlike factor. Its relationship to other members of this family, including the poxvirus growth factors from Shope fibroma virus and vaccinia virus, was analyzed. Alignment of DNA sequences and related open reading frames of myxoma virus and Shope fibroma virus indicated colinearity of genes between these poxviruses.     

C-terminal bombesin sequence requirements for binding and effects on protein synthesis in Swiss 3T3 cells.

The active-site serine of the extracellular beta-lactamases of Streptomyces cacaoi and Streptomyces albus G has been labelled with beta-iodopenicillanate. The determination of the sequence of the labelled peptides obtained after trypsin digestion of the denatured proteins indicate both enzymes to be class A beta-lactamases. Surprisingly the two Streptomyces enzymes do not appear to be especially homologous, and none of them exhibited a high degree of homology with the Streptomyces R61 DD-peptidase. Our data confirm that, as a family of homologous enzymes, class A is rather heterogeneous, with only a small number of conserved residues in all members of the class.     

The oxidation of the calcium probe quin2 and its analogs by prostaglandin H synthase

Quin2 and its analogs BAPTA, 5,5'-dimethyl BAPTA, 5,5'-difluoro BAPTA, fura-2, and indo-1 were developed to measure intracellular calcium concentrations. In this study we investigated whether quin2 and its analogs are susceptible to peroxidase-catalyzed oxidation. The hydroperoxidase activity of prostaglandin H synthase, like other peroxidases, is capable of oxidizing a wide variety of substrates. It was found that quin2 and its analogs served as reducing cofactors for the hydroperoxidase activity of prostaglandin H synthase, undergoing oxidation in the process. Furthermore, arachidonic acid metabolism was stimulated. Oxidation of quin2 and its analogs resulted in the formation of a carbon-centered radical, as could be detected by ESR, and in the formation of formaldehyde. Quin2 fluorescence decreased upon addition of arachidonic acid and prostaglandin H synthase. Furthermore, addition of calcium no longer resulted in an increase in quin2 fluorescence, as was observed prior to the addition of arachidonic acid and the enzyme. This indicates that one or more of the -N-CH2-COOH groups, which are responsible for the binding of calcium, were oxidized by the hydroperoxidase. Since prostaglandin H synthase is present in many cellular systems in which calcium concentrations are modulated, oxidation of the calcium probe might not only affect the measurement of intracellular calcium but could activate arachidonic acid metabolism as well.     

The selection of microbial communities by constant or fluctuating temperatures

Abstract The diversity of bacterial communities isolated from Antarctic lake sediment in chemostats under constant low temperature (8°C) or diurnally fluctuating temperature (1°C to 16°C) was examined. The median optimum temperature for growth of the freshwater bacteria isolated from the fluctuation chemostat was significantly lower ( P < 1%) than that for those from the constant temperature chemostat. The diversity of the enriched bacterial community isolated in the chemostat culture subjected to short-term temperature fluctuations was greater than that enriched under constant temperature. At least 4 different groups of bacteria, that occupied separate 'temperature niches', were isolated from the fluctuating chemostat compared to only one group isolated from the stable chemostat. Furthermore, a pseudomonad from the fluctuating chemostat was shown to out-compete another pseudomonad from the stable chemostat when both were subjected to the fluctuating temperature regime. However, the pseudomonad of constant (8°C) temperature origin out-competed that isolated under fluctuating conditions when subjected to a stable temperature regime.     

The influence of porphyrins on iron-catalysed generation of hydroxyl radicals.

Uroporphyrin I, haematoporphyrin and haematoporphyrin derivative had no effect on O2-. generation during oxidation of hypoxanthine by xanthine oxidase and on the formation of hydroxyl radicals (OH.) in the hypoxanthine/xanthine oxidase/Fe3+-EDTA/deoxyribose system. On the other hand, these porphyrins strongly inhibited O2-. formation in a horseradish peroxidase/H2O2/NADPH mixture, whereas they augmented OH. generation in this system after addition of Fe3+-EDTA. Experimental evidence suggests that these observations should be ascribed to the formation of a porphyrin anion radical in the horseradish peroxidase/NADPH system. The formation of this anion radical was confirmed by e.s.r. spectroscopy. This radical is apparently unable to reduce cytochrome c, but it can replace O2-. in the OH.-generating Haber-Weiss reaction.     

A comparative study of the development of Eimeria nieschulzi in vitro under aerobic and reducing conditions

Sporozoites of the rat coccidian, Eimeria nieschulzi Dieben, 1924 (Apicomplexa: Eimeriidae), were inoculated onto monolayers of normal rat kidney (NRK) fibroblasts and cultured either under aerobic (5% CO2/95% air) or reducing (desiccator jars modified into candle jars) conditions in RPMI-1640 supplemented with 5% fetal bovine serum, sodium bicarbonate, and antibiotics. Under aerobic conditions, first-generation meronts were observed at 2 days postinoculation (DPI) and, except for individual third-generation meronts that were seen at 5 and 6 DPI, no further development was noted. Under reducing conditions, however, first-generation meronts observed at 2-5 DPI underwent additional development to form second-generation meronts (3-5 DPI), third-generation meronts (3-7 DPI), and a small number of fourth-generation meronts (5-8 DPI). Both second- and third-generation meronts were abnormal, exhibiting gigantism although the merozoites produced appeared normal. The gradual degeneration of cell monolayers under reducing conditions prevented further observations beyond 8 DPI. These results suggest that atmospheric conditions play an important role in the development of E. nieschulzi and maintenance of reducing conditions may be one key to achieving enhanced development of some species of coccidia in vitro.     

Enhancement of allergic lung sensitization in mice by ozone inhalation

Inhaled ozone was found to exert an enhancing effect for allergic lung sensitization when mice contracted an aerosolized allergen. The animals were exposed to ozone concentrations of 0.24, 0.16, 0.13, and 0.10 ppm. After 4 days of continuous ozone exposure, the mice had allergen contact from an aerosolized solution of ovalbumin. The animals were then maintained in ambient air for several days before the cycle of ozone and aerosolized allergen was repeated over four allergen contact cycles. Mice were rested in ambient air for a week after the last allergen contact, and they were then tested for allergic sensitization by the intravenous injection of 2 mg of ovalbumin to induce anaphylactic shock in allergic individuals. The control groups of mice were maintained in ambient air throughout the experiment, but they experienced identical allergen contact with the ozone-exposed mice. The phenomenon of allergic enhancement from ozone inhalation was detected at 0.24, 0.16, and 0.13 ppm of ozone. The enhancing effect disappeared at 0.10 ppm of ozone. The study indicated a potential for increasing the number of allergically sensitized individuals when various allergens are inhaled during periods of high ozone exposure with the consequent adverse changes on respiratory membranes. The significance to human health of the allergic enhancement phenomenon by ozone needs investigation.