Existence of a Common Glycoprotein Homologous to S-Glycoproteins in Two Self-incompatible Homozygotes of Brassica campestris

S-Glycoproteins (S-locus-specific glycoproteins) in Brassicaspecies are present only in stigmas and thought to play an importantrole in self-incompatibility system. The stigma extract containsalso several other glycoproteins reacting with the antiserumto S-glycoproteins, among which some glycoproteins from S₈S₈-and S₉S₉-homozygotes have the same pI value. Both of the glycoproteinswhich were tentatively termed NS₈- and NS₈S₉-glycoproteins,respectively, were isolated and analyzed. Those were revealedto be identical. Its amino acid sequence was homologous withthe S-glycoproteins in Brassica species. The NS-glycoproteinswere expressed at the same time and only in stigma as S-glycoproteins. (Received July 19, 1988; Accepted September 7, 1988)     

Carbohydrate binding specificity of immobilized Allomyrina dichotoma lectin II

The carbohydrate binding specificity of Allomyrina dichotoma lectin II was investigated by analyzing the behavior of various complex type oligosaccharides and human milk oligosaccharides on an A. dichotoma lectin II-agarose column. Basically, the lectin interacts with the Gal beta 1----4GlcNAc group. Substitution of their terminal galactose residues by Neu5Ac alpha 2----6 will enhance their affinity to the lectin. By contraries, substitution at the C-2 or C-3 position of their terminal galactose with other sugars including sialic acid deprives their affinity to the lectin. With this characteristic, the immobilized lectin column can be used to separate complex type oligosaccharides with the Neu5Ac alpha 2----6Gal beta 1----4GlcNAc group from their isomeric oligosaccharides with the Neu5Ac alpha 2----3Gal beta 1----4GlcNAc group, where Neu5Ac is N-acetylneuraminic acid.     

Effects of microsite light availability on the survival and growth of oak seedlings within a grassland

Effects of microsite light availability on the growth and survival of transplantedQuercus serrata Thunb. seedlings in aMiscanthus sinensis Anderss. grass canopy were investigated by a “plant's eye view” approach. Diffuse site factors, i.e., the fractional transmissions of diffuse photosynthetic photon flux density, were estimated at 15 cm aboveground in 108 microsites where the seedlings grew. Microsite diffuse site factors were significantly different between surviving and dead seedlings during the experiment period from April to October (F_[1,14]=10.9, P<0.01). Relative growth rate of dry weight for individual seedlings positively depended on the diffuse site factors (r²=0.482, P<0.001 in May; r²=0.312, P<0.001 in October). Only 16 seedlings produced their second stem flush within the grass canopy. The ratio of height to dry weight of the second stem flush was significantly higher for the seedlings grew in shady microsites than for those in less shady microsites (r²=0,471, P<0.01 in May). This study suggests that the microsite heterogeneity of light availability is one of the important factors affecting the establishment of tree seedlings in patchy grasslands.     

Root hydrotropism of an agravitropic pea mutant, ageotropum

We have partially characterized root hydrotropism of an agravitropic pea mutant, ageotropum (from Pisum sativum L. cv. Weibull's Weitor), without interference of gravitropism. Lowering the atmospheric air humidity inhibited root elongation and caused root curvature toward the moisture-saturated substrate in ageotropum pea. Removal of root tips approximately 1.5 mm in length blocked the hydrotropic response. A computer-assisted image analysis showed that the hydrotropic curvature in the roots of ageotropum pea was chiefly due to a greater inhibition of elongation on the humid side than the dry side of the roots. Similarly, gravitropic curvature of Alaska pea roots resulted from inhibition of elongation on the lower side of the horizontally placed roots, while the upper side of the roots maintained a normal growth rate. Gravitropic bending of Alaska pea roots was apparent 30 min after stimulation, whereas differential growth as well as curvature in positive root hydrotropism of ageotropum pea became visible 4–5 h after the continuous hydrostimulation. Application of 2,3,5-triiodobenzoic acid or ethyleneglycol-bis-( β -aminoethylether)-N,N,N',N'-tetraacetic acid was inhibitory to both root hydrotropism of ageotropum pea and root gravitropism of Alaska pea. Some mutual response mechanism for both hydrotropism and gravitropism may exist in roots, although the stimulusperception mechanisms differ from one another.     

Hydrotropism and Its Interaction with Gravitropism in Maize Roots

We have partially characterized root hydrotropism and its interaction with gravitropism in maize (Zea mays L.). Roots of Golden Cross Bantam 70, which require light for orthogravitropism, showed positive hydrotropism; bending upward when placed horizontally below a hydrostimulant (moist cheesecloth) in 85% relative humidity (RH) and in total darkness. However, the light-exposed roots of Golden Cross Bantam 70 or roots of a normal maize cultivar, Burpee Snow Cross, showed positive gravitropism under the same conditions; bending downward when placed horizontally below the hydrostimulant in 85% RH. Light-exposed roots of Golden Cross Bantam 70 placed at 70° below the horizontal plane responded positively hydrotropically, but gravitropism overcame the hydrotropism when the roots were placed at 45° below the horizontal. Roots placed vertically with the tip down in 85% RH bent to the side toward the hydrostimulant in both cultivars, and light conditions did not affect the response. Such vertical roots did not respond when the humidity was maintained near saturation. These results suggest that hydrotropic and gravitropic responses interact with one another depending on the intensity of one or both factors. Removal of the approximately 1.5 millimeter root tip blocked both hydrotropic and gravitropic responses in the two cultivars. However, removal of visible root tip mucilage did not affect hydrotropism or gravitropism in either cultivar.     

Inhibitory effects of various synthetic substrates for aminopeptidases on phagocytosis of immune complexes by macrophages

The inhibitory effects of various 7-(aminoacyl)-4-methylcoumarinylamides (AA-MCA's), synthetic substrates for aminopeptidases, on phagocytosis of immune complexes by guinea pig peritoneal macrophages were investigated by measuring the intracellular uptake of sensitized 51Cr-sheep erythrocytes and 125I-alpha-amylase complexed with homologous IgG2 antibody. Among the AA-MCA's examined, MCA compounds of hydrophobic amino acids (Phe, Tyr, Leu, and Pro) were found to inhibit the intracellular uptake and digestion of immune complexes. Sucrose density gradient centrifugation of the homogenates of macrophages treated with the inhibitors for 1 h at 37 degrees C showed that they modulated the lysosomes, resulting in a decrease in buoyant density of the organella. These effects of the inhibitors on the buoyant density of the lysosomes as well as on the phagocytic activity of macrophages disappeared upon removal of the inhibitors from the cells by washing. Since none of 7-amino-4-methylcoumarin, L-phenylalanine, and bestatin methyl ester could significantly inhibit the phagocytosis of immune complexes by macrophages, the MCA compounds of hydrophobic amino acids appear to inhibit the phagocytosis as a consequence of their lysosomotropic nature.     

Proteolytic modification of the amino-terminal and carboxyl-terminal regions of rat hepatic phenylalanine hydroxylase

Activation of rat liver phenylalanine hydroxylase by limited proteolysis catalyzed by chymotrypsin was investigated with the use of sodium dodecyl sulfate-polyacrylamide gel electrophoresis and high pressure gel filtration. Both activation and proteolysis were decreased by the addition of the natural cofactor, (6R)-tetrahydrobiopterin. From chymotryptic digests of the hydroxylase carried out in the presence and absence of (6R)-tetrahydrobiopterin, several different enzyme species were isolated by high pressure gel filtration. One species (subunit Mr = 47,000) with unchanged hydroxylase activity was isolated from the chymotryptic digest in the presence of (6R)-tetrahydrobiopterin; it was derived from the native enzyme (Mr = 52,000) by cleavage of the COOH-terminal Mr = 5,000 portion of the native enzyme. In the absence of (6R)-tetrahydrobiopterin, another species (subunit Mr = 36,000) was isolated. In addition to modification at the COOH-terminal end of the molecule, this species also had lost a Mr = 11,000 fragment from the NH2-terminal end of the hydroxylase. The Mr = 11,000 fragment was shown to include the phosphorylation site of the enzyme. This Mr = 36,000 species was 30-fold more active than the native phenylalanine hydroxylase when assayed in the presence of tetrahydrobiopterin. These results suggest that the regulatory domain that inhibits hydroxylase activity in the basal state may be located at the NH2 terminus of the phenylalanine hydroxylase subunit.     

Effect of DN-1417, a thyrotropin releasing hormone analog, on dopaminergic neurons in rat brain

Acute and chronic effects of γ-butyrolactone-γ-carbonyl-histidyl-prolinamide (DN-1417) were investigated on motor activity, dopamine (DA) metabolites and DA receptors in various brain regions of rats. The motor activity, as measured with Automex recorder, was enhanced after a single injection with DN-1417 (20 mg/kg, IP), and the motor stimulating action persisted during 21 daily injections. Acute DN-1417 elevated both homovanillic acid (HVA) and 3,4-dihydroxyphenylacetic acid (DOPAC) levels in 7 brain regions, prefrontal cortex polar, medial and lateral fields, nucleus accumbens, olfactory tubercles, amygdala and striatum. After chronic treatment for 7 days, the acute effect of DN-1417 on DA metabolites disappeared in all regions except for the striatum in which DN-1417 still increased HVA and DOPAC. The response of striatal DA metabolites was also observed after chronic treatment for 21 days. Chronic DN-1417 produced no significant change in ³H-spiperone binding in the prefrontal cortex, nucleus accumbens, olfactory tubercles and striatum, while striatal ³H-DA binding displaced by 30 nM spiperone was enhanced after chronic treatment. These results indicate that DN-1417 interacts with mesocortical, mesolimbic and nigrostriatal DA systems in the different modes of action. The lack of tolerance to motor hyperactivity, however, raises the question as to whether DN-1417-induced hyperactivity may be mediated by the activation of mesolimbic DA neurons. The involvement of nigrostriatal neurons in DN-1417-induced motor hyperactivity is suggested.