Autoxidation of oxymyoglobin. An overall stoichiometry including subsequent side reactions

Oxymyoglobin (MbO2) is oxidized easily to metmyoglobin (metMb) with generation of the superoxide anion, which can be converted by the spontaneous dismutation into H2O2, this being also a potent oxidant of MbO2. In the presence of sodium azide in stoichiometric amounts, however, the rate of autoxidation of MbO2 increased rapidly with increasing concentration of the anion, but soon reached a saturating level, the extent of which was about twice that of the normal autoxidation in buffer alone. Quantitative analysis has revealed that this enhancement is not due to the nucleophilic displacement of O2- from MbO2 by the anion (Satoh, Y., and Shikama, K. (1981) J. Biol. Chem. 256, 10272-10275), but is due to the additional oxidation of MbO2 by H2O2 freed from the metMb being occupied by the anion at the sixth coordination position. Based on these novel results and stoichiometric considerations, it is possible to propose a new view that H2O2 produced from O2- can be eliminated or decomposed mostly, if not completely, by the metMb resulting from the normal autoxidation reaction of MbO2, presumably via the formation of the ferryl species.     

Solubilization and Characterization of the Nitrendipine Receptor in Rat Brain

The nitrendipine receptor associated with the voltage-dependent calcium channel in rat brain was solubilized by detergent extraction and sonication. The detergent solution used for extraction consisted of 10 mM 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS), 0.25% (wt/vol) polyoxyethylene 20 cetyl ether (Brij 58), and 0.025% (wt/vol) polyoxyethylene 17 cetyl stearyl ether (Lubrol WX) in the presence of 30% (wt/vol) glycerol as a stabilizer. The molecular weight of the receptor was estimated to be 1,800K by Sephacryl S-500 gel filtration and 800K by sucrose density gradient sedimentation. The equilibrium dissociation constant of [3H]nitrendipine to the solubilized receptors was 5.6 nM, which is approximately 10 times that of the membrane-bound receptor. The binding of nitrendipine to the receptor was inhibited noncompetitively by the structurally unrelated calcium channel inhibitors verapamil and prenylamine; their concentrations for 50% inhibition were both 1.0 X 10(-7) M, and they caused maximal inhibitions of 70 and 100%, respectively.     

Method of separating mouse platelets by discontinuous sucrose-gradient centrifugation

A discontinuous sucrose gradient was employed in the separation of mouse blood platelets using a modified Booyse method. The platelets of male CD-1 mice aged 8 to 12 weeks were divided into five distinct populations (A, B, C, D & E). Distribution of light to heavy platelets patterns in 10 normal CD-1 mice was demonstrable at; A (S.G. 1.188), as 14.8 +/- 5.6%; B (S.G. 1.199), 44.0 +/- 4.6%; C (S.G. 1.207), 24.1 +/- 3.4%; D (S.G. 1.214), 13.0 +/- 3.6%; and E (S.G. 1.221), 4.0 +/- 1.5%.     

Assignment of the prealbumin (PALB) gene (familial amyloidotic polyneuropathy) to human chromosome region 18q11.2–q12.1

Summary The assignment of the human prealbumin (PALB) gene to chromosome region 18q11–q12.1 has been achieved using a human genomic probe in the study of human-mouse somatic cell hybrids and by in situ hybridization. Because familial amyloidotic polyneuropathy was reported previously to be due to a mutation in prealbumin, it can be inferred that the gene for this disorder also maps to 18q11.2–q12.1.     

Transgenic tobacco resistant to a bacterial disease by the detoxification of a pathogenic toxin

Summary Some plant pathogens produce toxins which cause disease in infected plants. One of the pathogenic toxins, tabtoxin, is produced by Pseudomonas syringae pv. tabaci, which causes wildfire of tobacco. A tabtoxin resistance gene (ttr) coding for an acetyltransferase isolated from Pseudomonas syringae pv. tabaci was fused to the 35S promoter of the cauliflower mosaic virus (CaMV) to construct a chimeric gene for introduction into tobacco cells by Agrobacterium-mediated transformation. The transgenic tobacco plants showed high specific-expression of the ttr gene and no chlorotic symptoms caused by tabtoxin treatment or with infection by Pseudomonas syringae pv. tabaci. These results demonstrate a successful approach to obtain disease-resistant plants by detoxification of the pathogenic toxins which play an important role in pathogenesis.     

A game analysis of reciprocal cooperation: Sequential food-sharing and sex role alternation

The evolution of reciprocal cooperation between non-relatives is studied. Food-sharing of vampire bats studied by Wilkinson (1984) and egg-trading of simultaneous hermaphroditic fish studied by Fisher (1980) are respectively considered as Thompson's reciprocal assistance and the iterated Hero game. Those models predicted the following: (1) Reciprocal assistance between adult bats is evolutionarily stable if they repeatedly interact for a long time. However, (2) the cost for an adult to assist a juvenile is too high to be compensated by the benefit from the juvenile. (3) A particular signal, which determines the sex role of each partner, is always displayed by a “heroic” partner which releases eggs with a larger cost. (4) If alternation of sex roles is established, then the evolutionarily stable frequency of displaying a signal of egg-release increases as the frequency of divorce decreases, and (5) a “cheating” strategy, which releases sperm on every spawning bout, is less advantageous than reciprocal cooperation.     

Comparison of growth properties of carrot hairy root in various bioreactors

Summary Growth properties of carrot hairy root cells in various bioreactors were investigated. A turbine-blade reactor and an immobilized rotating drum reactor were found to be advantageous for the hairy root culture because of a high oxygen transfer coefficient (k in L a). After 30 days of culture, 10 g/l of dry hairy root cells were obtained in both bioreactors and maximum growth rates (V _m ) were found to be 0.63 and 0.61 g/l per day for the turbine-blade reactor and immobilized rotating drum reactor, respectively. Specific growth rates () at various cultivation times were observed to be linearly proportional to X/k _l a for both bioreactor configurations where X is the cell concentration. The estimated specific oxygen uptake rate of 0.34 mmol O₂/g dry cells per hour compares fairly well with an experimental value of 0.3.     

Membrane viscosity of lymphocytes and influence of phytohemagglutinin

The membrane viscosity of peripheral blood lymphocytes (PBLs) of equine, bovine and canine was measured by the use of time-resolved fluorescence depolarization technique with 1, 6-diphenyl-1,3,5-hexatriene (DPH). The viscosity values were 0.55, 0.59 and 0.50 poise for equine, bovine and canine PBLs, respectively. These values were compared with steady-state anisotropies and order parameters measured from electron spin resonance (ESR) of 5-doxyl stearic acid. Both values were increased with increase of viscosity. The fluid property of the membranes stimulated with phytohemagglutinin-P (PHA) was measured with steady-state fluorescence anisotropy and ESR. Little change of membrane fluidity was recognized with both methods during the stimulation with PHA. It appears that PHA activation process for these lymphocytes does not included large increase of the membrane fluidity which significantly accelerate the diffusion velocity of receptors in the plasma membrane.     

The production of pheromone clouds by spraying in the melon fly,Dacus cucurbitae coquillett (Diptera: Tephritidae)

Pheromone clouds sprayed by melon fly males were visually detected by focusing a beam of light at them during dusk when the males were vibrating their wings. The clouds were sprayed to the front, rear and upper sides of the male. We found that special morphological structures are used for spraying the pheromone clouds. When a male melon fly engages in calling behavior, sex pheromone droplets are excreted from his anus. This excretion is wiped off with the tarsus of his hind leg, and then it is deposited on the sexually dimorphic cubital cell hairs on the wing. During wing vibration, the targal bristles on the 3rd abdominal segment, which are peculiar to males, are rubbed against the specialized hairs of the cubital cell. Calling males sprayed clouds of pheromone with these actions. This paper was presented at the 32nd Annual Meeting of the Japanese Society of Applied Entomology and Zoology (Kochi, April, 1988).     

Selective production of glutamate by an immobilized marine blue-green alga,Synechococcus sp.

Summary Among 200 strains of marine bluegreen algae isolated from the coastal areas of Japan, the marine blue-green alga Synechococcus sp. NKBG 040607 excreted glutamate at the highest rate, 82.6% of total amino acids production being glutamate. Synechococcus sp. NKBG 40607 was immobilized in calcium alginate gel. Glutamate production by immobilized cells was double that of native cells. Maximal glutamate production (25 g/cm³ gel per day) of the immobilized cells was observed under a light intensity of 144 Einstein/m² per second at a cell concentration of 7.5 mg dry cells/cm³ gel. Immobilized cells of Synechococcus sp. can use nitrate as a nitrogen source. Immobilized marine Synechococcus sp. produced 0265 mg/cm³ gel of glutamate for 7 days in the presence of chloramphenicol.