The spatial patterns of parasitism of eumenid wasps,Anterhynchium flavomarginatum andOrancistrocerus drewseni by the miltogrammine flyAmobia distorta

1. Spatial patterns of parasitism of eumenid wasps Anterhynchium flavomarginatum and Orancistrocerus drewseni by the miltogrammine fly Amobia distorta were studied in Kyoto, Japan during 1980–1984.
2. In generations of low (<5%) and medium (5–20%) parasitism, percent parasitism per shed (the habitat of the hosts) increased as a function of host density. Conversely, in generations of high (>20%) parasitism, percent parasitism was rather constant over different host densities.
3. The spatial distributions of adult miltogrammine flies among sheds were censused in generations of low and medium parasitism. The frequency of observations of adult miltogrammine flies was higher at sheds of higher host density (aggregative behavioral response), but on the other hand, the adult miltogrammine flies distributed in an underdispersed (or regular) manner in relation to other conspecifics.
4. The spatially density independent relationship between host density and percent parasitism in generations of high parasitism was explained in relation to parasitoid dispersal from patches of high parasitoid density.

     

Bacterial NADH-quinone oxidoreductases

The NADH-quinone oxidoreductases of the bacterial respiratory chain could be divided in two groups depending on whether they bear an energy-coupling site. Those enzymes that bear the coupling site are designated as NADH dehydrogenase 1 (NDH-1) and those that do not as NADH dehydrogenase 2 (NDH-2). All members of the NDH-1 group analyzed to date are multiple polypeptide enzymes and contain noncovalently bound FMN and iron-sulfur clusters as prosthetic groups. The NADH-ubiquinone-1 reductase activities of NDH-1 are inhibited by rotenone, capsaicin, and dicyclohexylcarbodiimide. The NDH-2 enzymes are generally single polypeptides and contain non-covalently bound FAD and no iron-sulfur clusters. The enzymatic activities of the NDH-2 are not affected by the above inhibitors for NDH-1. Recently, it has been found that both of these types of the NADH-quinone oxidoreductase are present in a single strain of bacteria. The significance of the occurrence of these two types of enzymes in a single organism has been discussed in this review.     

Carboxyl methylation and farnesylation of transducin gamma-subunit synergistically enhance its coupling with metarhodopsin II.

A heterotrimeric G-protein in vertebrate photoreceptor cells is called transducin (T alpha beta gamma), whose gamma-subunit is a mixture of two components, T gamma-1 and T gamma-2. T gamma-2 is S-farnesylated and partly carboxyl methylated at the C-terminal cysteine residue, whereas T gamma-1 lacks the modified cysteine residue. To elucidate the physiological significance of the double modifications in T gamma, we established a simple chromatographic procedure to isolate T gamma-1, methylated T gamma-2 and non-methylated T gamma-2 on a reversed phase column. Taking advantage of the high and reproducible yield of T gamma from the column, we analyzed the composition of T gamma subspecies in the T alpha-T beta gamma complex which did not bind with transducin-depleted rod outer segment membranes containing metarhodopsin II. The binding of T alpha-T beta gamma with the membranes was shown to require the S-farnesylated cysteine residue of T gamma, whose methylation further enhanced the binding. This synergistic effect was not evident when T alpha was either absent or converted to the GTP-bound form which is known to dissociate from T beta gamma. Thus we concluded that a formation of the ternary complex, T alpha-T beta gamma-metarhodopsin II, is enhanced by the farnesylation and methylation of T gamma. This suggests that the double modifications provide most efficient signal transduction in photoreceptor cells.     

Purification and characterization of a heat-stable enterotoxin of Vibrio mimicus

A heat-stable enterotoxin produced by Vibrio mimicus (VM-ST) was studied. VM-ST was purified from a culture supernatant of V. mimicus strain AQ-0915 by ammonium sulfate fractionation, hydroxyapatite treatment, ethanol extraction, column chromatography on both SP-Sephadex C-50 and DEAE-Sephadex A-25, and HPLC, and the recovery rate was about 15%. Purified VM-ST was heat-stable. VM-ST activity was cross-neutralized by anti-STh antiserum. The amino acid composition of the purified VM-ST was determined 17 amino acid residues in the following sequence: Ile-Asp-Cys-Cys-Glu-Ile-Cys-Cys-Asn-Pro-Ala-Cys-Phe-Gly-Cys-Leu-Asn. This composition and sequence were identical to those of V. cholerae non-O1-ST. These results clearly demonstrate the production of a characteristic VM-ST by V. mimicus.     

A new trisaccharide sugar chain linked to a serine residue in bovine blood coagulation factors VII and IX

A new trisaccharide sugar chain was identified in bovine blood coagulation factors VII and IX. A pentapeptide isolated from factor VII contained Ser-52, which could not be identified with a gas-phase sequencer, suggesting an unknown substituent on the serine residue (Takeya, H. et al. (1988) J. Biol. Chem., in press). The same results were obtained for a pentapeptide containing Ser-53 of factor IX. Component sugar analysis revealed that the peptide contained 1 mol of glucose and 2 mol of xylose. This sugar component was also confirmed by high-resolution fast atom bombardment mass spectrometric analysis of the pentapeptide. The trisaccharide was released from the peptides by means of beta-elimination reaction and its reducing end was coupled with 2-aminopyridine. The fluorescent pyridylamino (PA-) derivative of the trisaccharide was purified by gel-filtration and reversed-phase HPLC. The sugar composition of the PA-trisaccharide was found to be 2 mol of xylose and 1 mol of PA-glucose. These results indicate the existence of a (Xyl2)Glc-Ser structure in factors VII and IX.     

Enhancement of ATPase Activity by a Lipid Peroxide of Arachidonic Acid in Rat Brain Microvessels

The effects of 15-hydroperoxyarachidonic acid (15-HPAA) on Na+, K+- and Mg+-ATPase activities in the blood-brain barrier (BBB) were examined using rat brain microvessels (MV). 15-HPAA markedly stimulated these ATPase activities in MV at low concentrations whereas the synaptosomal Na+, K+-ATPase activity was inhibited in a dose-dependent manner. Further neurochemical analysis revealed that this stimulatory effect of 15-HPAA in MV was not due to a simple detergent-like action of the compound on the membranes but rather to stimulation of the phospholipase A2 and lipoxygenase activity within MV. In addition, it was shown that free radical reactions were involved in the mechanism. Since such anti-edema drugs as 1,2-bis(nicotinamido)propane were proved to be potent suppressors of the enhanced ATPase activity, further speculations on the role of this effect for ischemic brain edema are offered.     

Thermal Properties of Membrane Lipids from two Cyanobacteria, Anacystis nidulans and Synechococcus sp.

The composition and positional distribution of fatty acids inmonogalactosyldiacylglycerol, digalactosyldiacylglycerol, phosphatidylglyceroland sulphoquinovosyldiacylglycerol from two cyanobacteria, Anacystisnidulans and Synechococcus sp. grown at 25°C have been determinedand compared with measurements of the phase separation temperaturesof the lipids. Only monogalactosyldiacylglycerol in Anacystisand sulphoquinovosyldiacylglycerol in Synechococcus showed phaseseparation temperatures above 0°C. The phase transitiontemperature of a sample of sulphoquinovosyldiacylglycerol containingover 90% of the dihexadecanoyl molecular species has been determinedto be 43°C for the Na⁺ salt and 38°C for the Mg⁺⁺ salt. ^*Deceased. September 14, 1986. (Received June 25, 1986; Accepted August 25, 1986)     

Effects of short-term treatment with calcium on the parathyroid gland of the rat,under particular consideration of the alteration of storage granules

Summary Short-term effects of CaCl₂-treatment on parathyroid cells of the rat, especially on their storage granules, were studied at the ultrastructural level. After an injection of 4% CaCl₂, serum calcium levels (SCL) rapidly increased from 9.1 mg/dl (controls) to a maximum of 14.9 mg/dl at 20 min. At 5 min after the injection, the number of type-I storage granules (large core) [NSG-I] and that of type-II storage granules (small core) [NSG-II] remained unchanged, in spite of elevated SCL (12.4 mg/dl). As soon as SCL rose to 13.2 mg/dl at 7.5 min, NSG-I gradually decreased to a minimum at 30 min; in contrast, NSG-II gradually increased to a maximum at 30 min. Vacuolar bodies also increased together with the augmentation of type-II storage granules. The average diameter of the core of the storage granules decreased significantly after the injection. Protein A-gold method for immunocytochemistry showed that the cores of these granules contain parathormone. Acid-phosphatase activity was occasionally found in storage granules of both types, especially in those of type II. It is concluded (i) that type-I storage granules may be transformed into vacuolar bodies via type-II granules as a result of hydrolysis, and (ii) that these processes may be accelerated during hypercalcemia.     

Primary structure of heat-stable enterotoxin produced by Yersinia enterocolitica

A heat-stable enterotoxin was isolated and purified from the culture supernatant of $\text{Yersinia enterocolitica}$ by reversed-phase high-performance liquid chromatography. The amino acid sequence of the purified toxin was determined to be as follows: Gln-Ala-Cys(X)-Asp-Pro-Pro-Ser-Pro-Pro-Ala-Glu-Val-Ser-Ser-Asp-Trp-Asp-Cys-Cys-Asp-Val-Cys-Cys-Asn-Pro-Ala-Cys-Ala-Gly-Cys (X: not determined). The C-terminal sequence containing 6 half-cystine residues was highly homologous to that of heat-stable enterotoxin of enterotoxigenic $\text{Escherichia coli.}$