Phototropic stimulation does not induce unequal distribution of indole-3-acetic acid in maize coleoptiles

Distribution of endogenous diffusible auxin into agar blocks from phototropically stimulated maize coleoptile tips was studied using a bioassay and a physicochemical assay, to clarify whether phototropism in maize coleoptiles involves a lateral gradient in the amount of auxin. At 50 min after the onset of phototropic stimulation, when the phototropic response was still developing, direct assay of the blocks with the Avena curvature test showed that the auxin activity in the blocks from the shaded half-tips was twice that of the lighted side, at both the first and second positive phototropic curvatures. However, physicochemical determination following purification showed that the amount of indole-3-acetic acid (IAA) was evenly distributed in the blocks from lighted and shaded coleoptile half-tips at both the first and second positive phototropic curvatures. The even distribution of the IAA was also confirmed with the Avena curvature test following purification by HPLC. These results indicate that phototropism in maize coleoptiles is not caused by a lateral gradient of IAA itself and thus cannot be described by the Cholodny-Went theory. Furthermore, the lower auxin activity in the blocks from the lighted half-tips suggests the presence of inhibitor(s) interfering with the action of auxin and their significant diffusion from unilaterally illuminated coleoptile tips.     

Transformation of Zea mays L. Using Agrobacterium tumefaciens and the Shoot Apex

Agrobacterium tumefaciens is established as a vector for gene transfer in many dicotyledonous plants but is not accepted as a vector in monocotyledonous plants, especially in the important Gramineae. The use of Agrobacterium to transfer genes into monocot species could simplify the transformation and improvement of important crop plants. In this report we describe the use of Agrobacterium to transfer a gene into corn, the regeneration of plants, and detection of the transferred genes in the F₁ progeny. Shoot apices of Zea mays L. variety Funk's G90 were cocultivated with A. tumefaciens EHA 1, which harbored the plasmid pGUS3 containing genes for kanamycin resistance (NPT II) and β-glucuronidase (GUS). Plants developed from these explants within 4 to 6 weeks. Fluorometric GUS assays of leaves and immature seeds from the plants exhibited low GUS activity. Both NOS and GUS gene fragments were amplified by polymerase chain reaction in the DNA isolated from the F₁ generations of one of the original transformed plants. Southern analysis showed both GUS and NPT probes hybridized to DNA in several of the F₁ progeny, demonstrating the incorporation of GUS and NPT II genes into high molecular weight DNA. These data establish successful gene transfer and sexual inheritance of the genes.     

Growth Yields and Maintenance Coefficients of Unadapted and NaCl-Adapted Tobacco Cells Grown in Semicontinuous Culture

Comparison of carbon utilization between unadapted and NaCl (428 millimolar) adapted tobacco (Nicotiana tabacum L.) cells under substrate limited growth conditions was facilitated using semicontinuous culture. Growth yields (Y_g) and maintenance coefficients (m) of unadapted and NaCl adapted cells were similar, indicating that the efficiency of carbon utilization for growth was not altered as a result of salt adaptation and that no additional metabolic costs were associated with growth of adapted cells in the presence of a high concentration (428 millimolar) of NaCl. The Y_g (0.588 grams organic dry weight gain per gram sugar uptake) and m values (0.117 grams sugar uptake per gram organic dry weight per day) were comparable in spite of substantial physiological and biochemical differences that exist between unadapted and NaCl adapted cells. Apparently, a metabolic homeostasis governs biomass production of cells before and after adaptation to salinity.     

13C-n.m.r. analysis of some sulphate derivatives of chitosan.

Positions of substitution with sulphate in three water-soluble sulphated derivatives of chitosan were analysed by 13C n.m.r. The structures of N-acetylchitosan 3,6-O-disulphate, sodium chitosan N-, 6-O-disulphate, and sodium chitosan 6-O-monosulphate were confirmed.     

Cell type-specific expression of the human renin gene.

We have previously produced transgenic mice carrying the human renin gene, whose expression is regulated in a tissue-specific manner. In the present study, we further characterized expression of the transgene. Northern blot analysis showed that the human renin gene is expressed in the kidney but not in the liver of two lines of transgenic mice with 10 and 50 copies of the transgene, suggesting that the integrated copy number of the human renin gene does not influence the dominant-renal expression pattern. Immunohistochemical study using a monoclonal antibody specific for human renin demonstrated that expression of human renin in the transgenic mouse kidney is confined to the epithelioid juxtaglomerular cells. Transfection experiments indicated that the chloramphenicol acetyltransferase fusion gene containing the 3-kb upstream sequences of the renin gene is activated only in human epithelioid embryonic 293 cells derived from kidney but not in human HepG2 cells from liver. These findings suggest that transfer of the cloned renin gene into mice and in vitro cultured cell lines can give rise to cell type-specific expression.     

Compressibility-structure relationship of globular proteins

The adiabatic compressibility, -beta s, of 11 globular proteins in water was determined by means of sound velocity measurements at 25 degrees C. All the proteins studied except for subtilisin showed positive -beta s values, indicating the large internal compressibility of the protein molecules. The intrinsic compressibility of proteins free from the hydration effect appeared to be comparable to that of normal ice. The compressibility data for 25 proteins, including 14 reported previously [Gekko, K., & Noguchi, H. (1979) J. Phys. Chem. 83, 2706-2714], were statistically analyzed to examine the correlation of the compressibility with some structural parameters and the amino acid compositions of proteins. It was found that -beta s increases with increasing partial specific volume and hydrophobicity of proteins. The helix element also seemed to be a dynamic domain to increase -beta s. Four amino acid residues (Leu, Glu, Phe, and His) greatly increased -beta s, and another four (Asn, Gly, Ser, and Thr) decreased it. Some empirical equations were derived for the estimation of the -beta s values of unknown proteins on the basis of their amino acid compositions. The volume fluctuations of proteins revealed by the compressibility data were in the range of 30-200 mL/mol, which corresponded to about 0.3% of the total protein volume. The conformational fluctuation seemed to enhance the thermal stability of proteins.     

Thioridazine enhances lysosomal accumulation of epidermal growth factor and toxicity of conjugates of epidermal growth factor with Pseudomonas exotoxin

Thioridazine, a phenothiazine calmodulin inhibitor, aggravated the cytotoxic effect of a conjugate (EGF-PE) of epidermal growth factor (EGF) coupled with Pseudomonas exotoxin against cultured HeLa cells. Other phenothiazine calmodulin inhibitors, trifluoperazine and chlorpromazine, also intensified the cytotoxic effect of EGF-PE, whereas N-(6-aminohexyl)-5-chloro-1-naphthalene sulfonamide (W7) had no such effect. By using iodinated epidermal growth factor ( [125I]EGF), the effect of thioridazine on intracellular transport of EGF was examined. The release of radioactivity associated with [125I]EGF into medium was slow in the presence of thioridazine. The Percoll gradient centrifugation pattern showed that thioridazine delayed both the appearance of [125I]EGF in lysosomes and the disappearance of [125I]EGF from the lysosomes. The pH value in lysosomes was 5.28 in thioridazine-treated HeLa cells, while that in untreated cells was 5.15. Thioridazine was found to inhibit lysosomal enzyme activities of cathepsin B and acid phosphatase, but not beta-hexosaminidase when cell extracts were treated with the drug. Electron microscopy showed an increased number of electron-dense bodies, possibly autophagosomes/lysosomes in HeLa cells grown for 48 h with 3 micrograms/ml thioridazine. The potentiating action of EGF-PE by thioridazine is discussed in relation to the altered lysosomal function in treated cells.     

Secreted agglutinability-masking factors in Issatchenkia scutulata var. scutulata

The agglutinability-masking factors (AMFs) of a and mating types of Issatchenkia scutulata var. scutulata were prepared from culture fluids. AMFs masked the agglutinability of opposite mating-type cells sex-specifically, just like agglutination substances responsible for sexual cell agglutination. a AMF adsorbed to cells was eluted by incubating the cells at 60°C for 10 min. AMF was prepared directly from culture fluids of cells by DEAE-cellulose ion exchange chromatography. The active part of the AMFs is thought to be a peptidyl moiety because of the sensitivity to subtilisin. The pretreatment of cells with AMF of the opposite mating-type was shown to promote zygote formation. AMF slightly inhibited growth in a cells but not in cells, while a AMF did not show any growth-inhibitory effect on either a or x cells.     

Phototropism in Hypocotyls of Radish : I. Isolation and Identification of Growth Inhibitors, cis- and trans-Raphanusanins and Raphanusamide, Involved in Phototropism of Radish Hypocotyls

Three growth inhibitors which might be involved in phototropism of Sakurajima radish (Raphanus sativus var. hortensis f. gigantissimus Makino) hypocotyls, were isolated as crystalline forms from light-exposed radish seedlings and identified as cis- and trans-raphanusanins and 6-methoxy-2,3,4,5-tetrahydro-1,3-oxazepin-2-one (designated raphanusamide). The cis- and trans-raphanusanins inhibited growth of etiolated radish hypocotyls at concentrations higher than 1.5 micromolar, raphanusamide at concentrations higher than 20 micromolar.     

Differentiation of oocyte- and somatic-type 5S rRNAs in animals

In some amphibians and bony fishes, oocyte- and somatic-type 5S rRNA genes are expressed differently in oocytes and somatic cells. In order to determine at what stage of animal evolution this differential expression system appeared and how it is regulated, the sequences of oocyte and somatic 5S rRNAs from three invertebrates (sea urchin, sea hare, and silkworm) and two vertebrates (lamprey and chick) were analyzed. It was found that the oocyte 5S rRNA from lamprey consists of two components, while its somatic 5S rRNA consists of only one. In other animals, such differential expression of 5S rRNA in oocytes and somatic cells was not seen. A phylogenetic tree of 63 animal 5S rRNAs was constructed by means of the parsimony method, and the evolution of oocyte and somatic-type 5S rRNAs was discussed.