Genetic mapping of mouseT3d andT3e betweenApoa1 andNcam

Mouse and human genetic nomenclature used in this text is in accordance with the International Committee on Standardized Genetic Nomenclature for Mice, and the Nomenclature Committee of the Human Gene Mapping Workshops, respectively.     

Ca2+/calmodulin-dependent protein phosphatase in bovine parotid gland: purification and characterization

Calmodulin-dependent protein phosphatase (CaM-PPase) was isolated from bovine parotid gland by sequential application of DEAE-52, Affi-gel blue and calmodulin-affinity chromatography followed by gel filtration and high performance liquid chromatography. The enzyme was activated in the simultaneous presence of Ni2+ or Mn2+ and Ca2+ plus calmodulin. Ca2+/calmodulin-dependent activation of CaM-PPase was antagonized by inhibitors of calmodulin action, such as W-7 and trifluoperazine. Tryptophan fluorescence was quenched in the presence of Ni2+. CaM-PPase was a heterodimer. The molecular weights of large subunits which bound calmodulin (CaM) were 68 kD and 58 kD - the 68 kD subunit was predominant. Polyclonal antibodies against bovine calcineurin cross-reacted with both types of larger subunits. Using polyclonal antibodies against bovine calcineurin or the monoclonal antibody against subunit B of bovine calcineurin, the smaller molecular weight subunit (19 kD) was found to be immunologically identical to subunit B of bovine calcineurin. In bovine parotid gland, CaM-PPase was found both in acinar and duct cells.     

A model for nonlinear stochastic behavior of the pupil

In binocular fusion, pairs of left and right stimuli yielding the same brightness perception constitute an equibrightness curve in a coordinate system whose ordinate and abscissa correspond to the left and right stimulus strengths. A neural network model is presented to elucidate the characteristics of the curve. According to the model, Fechner's paradox is due to the threshold characteristics of the neuron. If the shapes or movements are radically different between the left and right stimuli, the retinal rivalry is caused. That is, only the left stimulus is perceived at one moment and the right stimulus at another moment. The period of left or right eye dominance alternates randomly from time to time. The distribution of the period is approximate to the gamma distribution. In order to account for this fact, a neural network model is proposed, which consists of a pair of neurons receiving inputs with stochastic fluctuations. The computer simulation was carried out with satisfactory results. The model of retinal rivalry is integrated with that of brightness perception.     

Promotion of Infection Thread Formation by Substances from Rhizobium

An extrinsic substance (ES-6000) was isolated from the periplasmic space of Rhizobium trifolii (strain 4S) cells by osmotic shock, using a high-density sucrose solution. This substance promoted infection thread formation in root hairs of white clover when inoculated together with the infectious strain (4S). However, ES-6000 obtained from another rhizobial species and from strain A1, which is a noninfectious mutant strain obtained from strain 4S, did not have this effect. The promoter in the ES-6000 from strain 4S is a relatively small molecule since it passed through a hollow-fiber membrane (molecular weight, 6,000). This substance was also recognized as an R_f 0.1 fraction by paper chromatography. Sucrose was effective in promoting nodulation and root elongation.     

Growth yield from electrons available from substrates in aerobic- and photoheterotrophic cultures of Rhodopseudomonas sphaeroides S

A balance of electrons available from acetic acid consumed for growth and oxygen uptake in the aerobic- and photoheterotrophic growth of Rhodopseudomonas sphaeroides S on acetate-minimal medium could be realized the same as in the carbon balance. The unmeasured amounts of yeast extract consumed by the cells grown on propionate–yeast extract media were indirectly estimated from the balance equation of electrons available from carbon substrates. The specific consumption rate of the yeast extract increased with an increase in propionate consumption rate in aerobic and photoheterotrophic cultures. Growth yields from acetic acid and from propionic acid plus yeast extract were calculated on the electron level, i.e., Y_X/ave g cell produced/equivalent electrons available from substrate consumed. Y_X/ave values were 5.0 to 5.8 g cell/ave in photoheterotrophic cultures and 2.7 to 3.6 in aerobic–heterotrophic cultures regardless of different medium compositions.     

Quantitative structure-activity relationship of cytokinin-active adenine and urea derivatives

The substituent effect of N⁶-alkyl and -aralkyl adenines on the promotion of the growth of tobacco callus was analysed quantitatively using physico-chemical substituent parameters and regression analysis. The results indicated an optimum steric condition for activity in terms of the maximum width of the N⁶-substituents from the bond-axis connecting the N⁶-atom with its α carbon atom. The electron withdrawing effect of the N⁶-substituent enhances the activity. The substituent effect on the cytokinin activity of phenyl- and diphenyl- urea derivatives determined by Bruce and Zwar using the tobacco pith-block assay was also analysed. The results suggest that position-specific steric and hydrophobic effects of aromatic substituents participate in the variation in activity rationalizing the general trend of the activity; meta >para >ortho derivatives, for both series of compounds. The electronic effect is significant for the activity of diphenylureas but not for that of phenylureas which show somewhat different modes of interaction between the two series at the site of action. Based on inferences made from the correlations, hypothetical maps for the mode of interaction of these three sets of compounds at the site of action have been proposed.     

Hypotensive mechanism of [Leu13]motilin in dogs in vivo and in vitro.

The effects of [Leu13]motilin were examined in vivo after its intravenous administration into anesthetized dogs and in vitro with isolated preparations of canine mesenteric artery. [Leu13]Motilin (0.1-10 nmol x kg(-1), i.v.) induced both strong and clustered phasic contractions in the gastric antrum and duodenum. At doses of over 1 nmol x kg(-1), [Leu13]motilin also produced transient decreases in arterial blood pressure, left ventricular pressure, maximum rate of rise of left ventricular pressure, and total peripheral resistance, and an increase in aortic blood flow and heart rate. A selective motilin antagonist, GM-109 (Phe-cyclo[Lys-Tyr(3-tBu)-betaAla] trifluoroacetate), completely abolished the gastric antrum and duodenal motor responses induced by [Leu13]motilin. In contrast, hypotension induced by [Leu13]motilin (1 nmol x kg(-1)) was unchanged in the presence of GM-109. In isolated mesenteric artery preparations precontracted with U-46619 (10(-7) M), [Leu13]motilin (10(-8)-10(-5) M) induced an endothelium-dependent relaxation, and this was inhibited by a pretreatment with N(omega)-nitro-L-arginine, a competitive inhibitor of NO synthase (10(-4) M). A high dose (10(-4) M) of GM-109 slightly decreased [Leu13]motilin-induced relaxation, and shifted the concentration-response curve of [Leu13]motilin to the right. However, the pA2 value (4.09) of GM-109 for [Leu13]motilin in the present study was conspicuously lower than that previously demonstrated in the rabbit duodenum (7.37). These results suggest that [Leu13]motilin induces hypotension via the endothelial NO-dependent relaxation mechanism and not through the receptor type that causes upper gastrointestinal contractions.     

A quantitative investigation of irregular cuspules in human maxillary permanent molars

The frequency of occurrence of anomalous cusps or tubercles on human upper first molars was investigated in seven racial populations using moiré contourography, which permits the three-dimensional measurement of minute cusps. Tubercles on the mesial marginal ridge were more frequently found in Mongoloid populations (Japanese and Eskimo) than in others. The frequency of the protoconule was high in Eskimos and Negroids (Bantu and San). The lingual paracone tubercle (mesial cusp) showed a particularly high frequency in Australian aborigines. The metaconule was rare or absent in all of the populations. Caucasoid groups (Dutch White and Asiatic Indian) showed generally low frequencies of all these abnormal tubercles, especially the distal accessory cusp (C5). Racial differences in the frequencies of occurrence may offer a key to understanding the adaptive significance of these traits and human microevolution. Confusion in nomenclature for upper molar tubercles is also discussed.     

Effect of NaCl addition on nanosecond O2 escaping reaction of myoglobin: evidences for the transition of myoglobin dynamic structure at 20 degrees C.

We studied the nanosecond (ns) geminate O2 escape reaction from the protein interior of myoglobin (Mb) to the solvent phase in the temperature range of 5-40 degrees C containing 0-0.1 M NaCl. In the flash photolysis experiments, we found that both the rate constant, kout, and its Arrhenius plot changed upon the variation of the NaCl concentration. In particular, it was noteworthy that the Arrhenius plot of kout dramatically changed in its slope, keeping the break at 20 degrees C, upon the addition of NaCl, indicating that the thermodynamic parameters such as an enthalpy of activation (delta H not equal to) and an entropy of activation (delta S not equal to) are different between above and below 20 degrees C, and that they are further altered upon the NaCl addition to the sample solution. From these results, we suggested that the Mb dynamic structure in the ns geminate O2 escape reaction is sensitively regulated by the interaction of the protein surface and the salt. The present study also showed that an inconsistency of the Arrhenius plot of kout between Chatfield et al. ((1990) J. Am. Chem. Soc. 112, 4680-4687) and us ((1990) J. Biol. Chem. 265, 18823-18828) is probably due to the difference in the solution condition.     

Expression of a functional asialoglycoprotein receptor through transfection of a cloned cDNA that encodes a macrophage lectin.

The Gal/GalNAc-specific lectin on rat peritoneal macrophages (macrophage asialoglycoprotein binding protein, M-ASGP-BP) is structurally similar to rat hepatic asialoglycoprotein-binding protein (ASGP-BP) or rat hepatic lectin (RHL) and is highly homologous with the major component of RHL, RHL-1 (Ii, M, Kurata, H., Itoh, N., Yamashina, I., and Kawasaki, T. (1990) J. Biol. Chem. 265, 11295-11298). We found in this study that transfection with a cDNA clone that encodes a single polypeptide, M-ASGP-BP, was sufficient for the expression of an endocytic receptor for asialoorosomucoid (ASOR) on the COS-1 cell surface. The Kuptake value for ASOR for the transfected cells was 12.5 nM, which is similar to that for peritoneal macrophages (23 nM), and the number of ASOR bound on the cell surface was 1-8 x 10(5)/cell, this value being hundreds of times larger than that for peritoneal macrophages. 125I-ASOR bound on the surfaces of the transfected cells was rapidly internalized on incubation at 37 degrees C, and after 90 min of incubation, most of the radioactivity was recovered in acid-soluble degraded products from the medium. These results confirmed that the cDNA cloned in our previous study does in fact encode M-ASGP-BP and also that the single polypeptide chain can form a homooligomeric receptor (probably a hexamer or octamer) exhibiting high affinity for ASOR. The latter property was distinct from that of the hepatic ASGP-BP in that simultaneous transfection of two cloned cDNAs that encode RHL-1 and RHL-2/3 was required to produce an active ASOR receptor (McPhaul, M., and Berg, P. (1986) Proc. Natl. Acad. Sci. U. S. A. 83, 8863-8867). This M-ASGP-BP expression system may serve as a simple model with which to investigate the molecular mechanisms underlying carbohydrate-mediated endocytosis.