Synthesis and application of a new phosphorylating agent: S-(N-monomethoxytritylaminoethyl)-O-(o-chlorophenyl)phosphorothi oate

A new phosphorylating agent, S-(N-monomethoxytritylaminoethyl)-O-(O-chlorophenyl) phosphorothioate, was prepared and reacted with a 5'-hydroxyl group of an oligonucleotide using 1-mesitylene-sulfonyl-3-nitrotriazole (MSNT) as a condensing agent. After base labile protecting groups were removed, the partially deprotected oligonucleotide was separated on a reversed phase column and converted to the oligonucleotide with an aminoethyl or a phosphoryl group at the 5'-end by treatment with 80% acetic acid or iodine-water, respectively. The syntheses of ppT, pppT, A5'pp5'T and A5'ppp5'T were also performed by treatment of 5'-O-(N-monomethoxytritylaminoethylthiophosphoryl) thymidine with tri-n-octylammonium salt of phosphoric acid, pyrophosphoric acid, pA and ppA, respectively.     

Flower choice in honeybees: Effects of food value and flower density

To test the effects of food value on the flower choice, individual honeybees (Apis mellifera) were offered a choice of 25 % sucrose solution (SS) and 1 of 6 different SSs, ranging from 5 % to 50 % SS, at either a low or a high flower density. Artificial flowers were filled with each SS. The honeybees showed a stronger preference for a concentrated SS to a diluted SS at a high than at a low flower density, and the degree of preference was positively correlated to the difference in the sucrose concentration between paired SSs. These foraging patterns were consistent with qualitative predictions from optimal foraging theory. Furthermore, it was found that experience in feeding on a concentrated SS lowered the foraging motivation for a diluted SS at the high flower density, but not at the low flower density. I discuss the effects of food density, food profitability and experience on the foraging behaviour of honeybees.     

Computer determination of perfusion patterns in pulmonary capillary networks

Hanger, Christopher C., Robert G. Presson, Jr., Osamu Okada,Steven J. Janke, John J. Watkins, Wiltz W. Wagner, Jr., and Ronald L. Capen. Computer determination of perfusion patterns in pulmonarycapillary networks. J. Appl. Physiol.82(4): 1283-1289, 1997.Individual pulmonary capillaries are notsteadily perfused. By using in vivo microscopy, it can readily bedemonstrated that perfusion continually switches between capillarysegments and between portions of the network within a single alveolarwall. These changes in capillary perfusion occur even when upstream pressure and flow are constant. Flow switching between capillary segments in the absence of hemodynamic changes in large upstream vessels suggests that capillary perfusion patterns could be random. Tocalculate the probability that perfusion patterns could occur bychance, it is necessary to know the total number of possible perfusionpatterns in a given capillary network. We developed a computer programthat can determine every possible perfusion pattern for any givencapillary network, and from that information we can calculate whetherperfusion of individual segments in the network is random. With theresults of the computer program, we have obtained statistical evidencethat some capillary segments in a network are nonrandomly perfused.

     

A general characteristic of tumor mitochondria: Leakage of endogenous Mg2+ on incubation with uncoupler and resultant reduction of uncoupler-stimulated ATPase activity

Previous studies showed that stimulation of mouse mitochondrial ATPase activity of tumor cells, fetal liver, and adult brain by the uncoupler 2,4-dinitrophenol was markedly suppressed during incubation of the mitochondria with the uncoupler (J.-I. Hayashi et al., 1980, Biochem. Biophys. Res. Commun.92, 261–267). The present work showed the reason for this suppression. More than half the endogenous Mg²⁺ leaked from mitochondria of all tumor cells tested, and of fetal liver and adult brain during incubation with the uncoupler, while only about 30% of the endogenous Mg²⁺ leaked from mitochondria of other normal tissues. The effect of the uncoupler on Mg²⁺ leakage from liver mitochondria changed from the fetal to the adult type within about 30 min after birth. In hypotonic medium, normal liver mitochondria also lost more than half their total Mg²⁺ and concomitantly stimulation of their ATPase activity by uncoupler was considerably reduced. Exogenously added Mg²⁺ could reverse this reduced effect of the uncoupler on ATPase activity of mitochondria from normal tissues and tumor cells. These results show that the endogenous Mg²⁺ content of mitochondria directly affects the stimulation by uncoupler of ATPase activity of mitochondria from both normal tissues and tumor cells. Thus, mitochondria of all tumor cells tested, and of fetal liver and adult brain are leaky to Mg²⁺ during incubation with uncoupler and as a result of the leakage, the stimulatory effect of the uncoupler on their ATPase activity is greatly reduced.     

Role of prostaglandin endoperoxides in the serum thiobarbituric acid reaction

In the presence of heme and reduced glutathione, prostaglandin (PG) endoperoxides underwent rapid conversion to malondialdehyde and 12l-hydroxy-5,8,10-heptadecatrienoic acid. In addition, PG endoperoxides as well as lipid peroxides produced malondialdehyde to yield a red pigment during the thiobarbituric acid reaction with different efficiencies. The relative rates of the reaction were: 1,1,3,3-tetraethoxypropane, 100; PGG₂, 55; PGH₂, 32; and 15-hydroperoxyarachidonic acid, 6. The thiobarbituric acid reactive materials in rabbit serum decreased by 25–60%, after intravenous administration of aspirin (a cyclo-oxygenase inhibitor) and with a concomitant decline of serum PG levels. These results, taken together, suggested that serum thiobarbituric acid values, considered to be an indicator of lipid peroxide levels, were to a significant extent due to PG endoperoxides and their derivatives.     

Stimulating factor for calf thymus DNA polymerase β

A factor that stimulates purified DNA polymerase β about 2-fold was separated from DNA polymerase β activity on a DNA-cellulose column. During the early stage of purification, the factor may be associated with DNA polymerase β to form a complex that sediments at 3.9 S in sucrose gradients and behaved as a 52,000 dalton protein on a Sephadex G-100 column. The complex, which contains 40,000 and 12,500 dalton polypeptides, was insensible to the stimulator, and did not show any exonuclease activity.     

Detection of IgG antibody to measles virus by radioimmunoassay technique

A highly sensitive procedure of solid-phase radioimmunoassay (RIA) was developed for the detection of measles IgG antibody. HeLa cells persistently infected with measles virus were used as a solid-phase antigen. This technique was applied to the detection of measles IgG antibody in patients with subacute sclerosing panencephalitis (SSPE) and multiple sclerosis. Normal subjects having experienced natural measles or measles vaccination and patients with various neurological diseases of non-virus nature were also examined as control groups. Measles antibody was detected at high titers in both the sera and cerebrospinal fluid of SSPE patients. Moreover, RIA/HI ratios of SSPE patients were significantly higher than those of normal subjects, suggesting the presence in the formers of antibodies to nucleocapsids at high titers as well as to viral envelopes. On the other hand, no significant difference was found in both RIA and HI titers between the sera of multiple sclerosis and those of various neurological diseases.     

Study on the Correlation of Chemical Structure and Ovicidal Activities of 2-Bromoethylthiobenzenes

Formation of a sulfonium-like intermediate was assumed in the hydrolysis of the 2-bromoethylthiobenzenes. A linear free energy relationship was found between the hydrolysis rate of a certain substituted 2-bromoethylthiobenzene and the molar fraction of water in the solvent. The effect of the substituent on the rate constant was attributed not only to the activation energy but also to the entropy change of activation. The negative ρ-value in the formation of the sulfonium-like intermediate in aqueous solution was comparable with that obtained in the ρ-σ-π analysis for ovicidal activity of the compounds.

For the reaction of the substituted 2-bromoethylthiobenzenes with highly excess amount of 4-(p-nitrobenzyl)-pyridine, the ρ-value was found to be negative, which means that the formation of the sulfonium-like intermediate is a rate determining step. Whichever might be more important, the hydrolysis or alkylation, as to the ovicidal action of the compounds, the formation of the sulfonium-like intermediate, could be considered to be an essential step.     

Crystallization and preliminary X-ray analysis of plant class I chitinase from rice

We report here on crystallization and preliminary X-ray analysis of plant class I chitinase from rice (OsChia1b). Similar single crystals of full-length OsChia1b were obtained under two independent conditions. The crystals grown under these conditions diffracted up to 2.1 and 2.5 angstroms resolution, respectively, at a synchrotron beamline, and were found to belong to the tetragonal space group P4(3)2(1)2.