The membrane-associated ATPase from Sulfolobus acidocaldarius is distantly related to F1-ATPase as assessed from the primary structure of its alpha-subunit

Isolation of novel membrane-associated ATPases, presumably soluble parts of the H+-ATPases, from archaebacteria has been recently reported, and their properties were found to be significantly different from the usual F1-ATPase. In order to assess the relationship of the archaebacterial ATPases to the F1-ATPases and other known ATPases, the amino acid sequence of the alpha subunit of the ATPase from Sulfolobus acidocaldarius, an acidothermophilic archaebacterium, was compared with the sequences of other ATPases. The gene encoding its alpha subunit was cloned from the genomic library of S. acidocaldarius, and the nucleotide sequence was determined. The 591-amino acid sequence deduced from the nucleotide sequence contains a small number of short stretches that shows sequence similarity to the alpha and beta subunits of F1-ATPase. However, the overall similarity is too weak to consider it to be a typical member of the F1-ATPase family when the highly conserved sequences of the F1-ATPase subunits among various organisms are taken into account. Moreover, most of these stretches overlap the consensus sequences that are commonly found in some nucleotide-binding proteins. There is no significant sequence similarity to the ion-translocating ATPases, which form phosphorylated intermediates, such as animal Na+,K+-ATPases. Thus, the S. acidocaldarius ATPase and probably other archaebacterial ATPases also appear to belong to a new group of ion-translocating ATPases that has only a distant relationship to F1-ATPase.     

Leaf ultrastructure of C4 species possessing different Kranz anatomical types in the cyperaceae

The leaf ultrastructure of NADP-malic enzyme type C₄ species possessing different anatomical features in the Cyperaceae was examined: types were the Rhynchosporoid type, a normal Kranz type in which mesophyll cells are adjacent to Kranz cells, and Fimbristyloid and Chlorocyperoid types, unusual Kranz types in which nonchlorophyllous mestome sheath intervenes between the two types of green cells. They show structural characteristics basically similar to the NADP-malic enzyme group of C₄ grasses, that is, centrifugally located chloroplasts with reduced grana and no increase of mitochondrial frequency in the Kranz cells. However, the Kranz cell chloroplasts of the Fimbristyloid and Chlorocyperoid types exhibit convoluted thylakoid systems and a trend of extensive development of peripheral reticulum, although those of the Rhynchosporoid type do not possess such particular membrane systems. The suberized lamella, probably a barrier for CO₂ diffusion, is present in the Kranz cell walls of the Rhynchosporoid type and in the mestome sheath cell walls of the other two types, and tightly surrounds the Kranz cells (sheaths) that are the sites of the decarboxylation of C₄ acids. These ultrastructural features are discussed in relation to C₄ photosynthetic function.     

Immunohistochemical localization of Na+-dependent glucose transporter in rat jejunum

Summary Glucose is actively absorbed via a Na⁺-dependent active glucose transporter (Na-GT) in the small intestine. We raised a polyclonal antibody against the peptide corresponding to amino acids 564–575 of rabbit intestinal Na-GT, and localized it immunohistochemically in the rat jejunum. By means of immunofluorescence staining, Na-GT was located at the brush border of the absorptive epithelial cells of the intestinal villi. Electron-microscopic examination showed that Na-GT was localized at the plasma membrane of the apical microvilli of these cells. Little Na-GT was found at the basolateral plasma membrane. Along the crypt-villus axis, all of the absorptive epithelial cells in the villus were positive for Na-GT. In addition to the brush border staining, the supranuclear positive staining, which was shown to be the Golgi apparatus by use of electron microscopy, was seen in cells located between the base to the middle of the villus. Cells in crypts exhibited little or no staining for Na-GT. Goblet cells scattered in the intestinal epithelium were negative for Na-GT staining. These observations show that Na-GT is specific to the apical plasma membrane of the absorptive epithelial cells, and that the onset of Na-GT synthesis may occur near the crypt-villus junction.     

Silence of streptomycin 6-phosphotransferase gene derived by incubation at a high temperature inStreptomyces griseus

Summary The bald mutants from streptomycin (SM)-producingStreptomyces griseus 2247 obtained by incubation at high temperature (36° C), designated as HT strains, lost resistance to their own antibiotic and scarcely produced the antibiotic. Although SM susceptibility in the mutant was due to loss of SM 6-phosphotransferase activity produced in the cell, the gene coding for the enzyme cloned from an HT strain was surely expressed inS. lividans 1326 as a host. Northern blot analysis showed that the corresponding RNA is not detected in the mutant, indicating that though the gene encoding SM 6-phosphotransferase, at least, the structural gene is not deleted in the cell, the expression is silent.     

Ferricyanide Induces Flowering by Suppression of Nitrate Assimilation in Lemna paucicostata 6746

Lemna paucicostata 6746, a short-day plant, produced flowerbuds even under continuous light when cultured for 3 days inferricyanide containing ammonium-free medium followed by cultureon nitrogen-rich medium (either nitrate or ammonium). Dailytreatment with ferricyanide in the absence of ammonium for morethan 8 hours, which completely inhibited nitrate reductase activitywithin 6 hours after the addition to the medium, induced daylength-independentflowering even when the ammonium-rich medium was given duringthe remaining hours. The presence of ammonium for 1 hour atthe middle of the 14-h ferricyanide treatment almost completelysuppressed floral induction. (Received March 6, 1986; Accepted June 3, 1986)     

Inhibition of Flowering in the Long-Day Plant Lemna gibba G3 by Hutner's Medium and its Reversal by Medium Modification

The long-day plant Lemna gibba G3 flowers normally in E medium(Hoagland-type medium plus 30 µM EDTA) but in 0.5 H mediumthere is no flowering. Ammonium is present in 0.5 H medium andis known to inhibit flowering in L. gibba G3, but even in NH₄⁺-free0.5 H medium there is virtually no flowering under continuouslight. Increasing the phosphate concentration of the NH₄⁺-free0.5 H medium from 1.15 ITIM to 12 or 16 mM results in substantialflowering. Decreasing the EDTA concentration from 850 µIMto 250 µM, or raising the nitrate concentration from 4mM to 12 mM, results in only a small increase in flowering.If the decrease in EDTA and increase in nitrate are combinedwith the increase in phosphate, however, the flowering responseis nearly as good as that obtained using E medium. Thus, withthese three changes the inhibitory effect of NH₄⁺free 0.5 Hmedium for flowering in L. gibba G3 is almost completely reversed In the above studies flowering was not limited by daylength.When plants were grown on E medium under an 11 hour daylengthwhere flowering is limited by daylength, decreasing the phosphateconcentration in the medium reduced flowering, but increasingthe phosphate concentration in the medium did not stimulateflowering. Thus, when flowering is limited by daylength, highphosphate will not cause flowering, but a certain level of phosphateappears to be necessary for the expression of photoinductionunder long days. (Received January 14, 1986; Accepted June 24, 1986)     

Relative effectiveness and interaction of ultraviolet-B, red and blue light in anthocyanin synthesis of apple fruit

The effect of light on anthocyanin production in apple ( Malus pumila Mill. cv. Jonathan) skin disks was investigated, with prolonged irradiation from different light sources. High fluence rates of white light provided from a xenon lamp were unable to produce large amounts of anthocyanin, and anthocyanin production became saturated at about 30 W m⁻². When UV-B light, provided by a fluorescent lamp which had an emission peak at 312 nm, was combined with the white light, anthocyanin production was synergistically stimulated and increased up to the highest fluence rates of white light tested (44 W m⁻²). This UV-B light was more effective than red and blue light provided from fluorescent lamps, but anthocyanin production became saturated at about 1.7 W m⁻². However, simultaneous irradiation with red and UV-B light had a synergistic effect. UV-B light was also effective in increasing anthocyanin production in whole fruit. Therefore this synergism seemed to have an important role in the development of the desirable red skin color under field light conditions. The results of aminoethoxyvinylglycine treatment suggested that ethylene was not involved in the stimulative effect of UV-B light.     

Stability enhancement and circular dichroism spectral anomaly as an indication of non-covalent interactions in histidine- and tyrosine-containing ternary copper(II)—amino acid systems

Visible absorption and CD spectral and potentiometric studies on the His- and Tyr-containing ternary copper(II) complexes Cu(A)(L-B), where A refers to L-His, D-His, or L-Tyr and B to Lys, Tyr, Trp, Phe, Ala, Val, Arg, Glu, Asn, Gln, Ser, or Thr, were made to study ligand-ligand interactions in the complexes. While the CD spectral magnitudes in the d—d region are additive in the absence of side chain interactions and can be estimated from the magnitudes for the ternary systems involving DL-A or DL-B, deviation from the additivity was observed for Cu(L-His)(L-B) (B = LysH, Tyr, Trp, or Phe) and Cu(L-Tyr)(L-Trp). From the stability constants determined at 25 °C and I = 0.1 M (KNO₃), the equilibrium constants, K, for the following hypothetical equilibria were calculated to be large (0.14–0.60) for formation of Cu(L-/D-His)(L-B)(B = Tyr or Trp) and Cu(D-His)(L-Phe) with Cu(en)(L-Ala) as standard: $Cu(A)(L?Ala)+Cu(en)(L?b)\stackrel{K}{?}Cu(A)(L?B)+Cu(en)(L?Ala)$ The positive values indicate the stabilization due to the stacking between the imidazole ring of His and the aromatic side chain of L-B. Solvent dependence of the CD spectra for Cu(L-His)(L-LysH) and Cu(L-His) L-Trp) further supported the existence of the intramolecular electrostatic and hydrophobic interactions.     

An investigation for the occurrence of C4 photosynthesis in the Cyperaceae from Australia

Two hundred and twenty species of 38 genera in the Cyperaceae from Australia were examined for the possible occurrence of the C₄ photosynthesis and the anatomical features of leaves and culms. The Kranz type of anatomy and the carbon isotope ratios typical of C₄ plants were found in 84 species in the following six genera of four tribes belonging to subfamily Cyperoideae:Bulbostylis, Crosslandia, andFimbristylis (Fimbristylideae);Lipocarpha (Lipocarpheae);Cyperus (Cypereae);Rhynchospora (Rhynchosporeae). The anatomical observation revealed that the C₄ species possessed any one of the three Kranz anatomical types found by previous investigators. It was suggested that in the Cyperaceae the C₄ syndrome evolved independently within several taxa of the subfamily. The relative distribution of C₃ and C₄ species of the Cyperaceae in Australia was investigated by use of floristic data. It was recognized that the C₄ species dominated in the northern part of the continent which was characterized by tropical and subtropical savannas and hot dry areas with summer rainfall, and the C₃ species in the southern part, which contained temperate areas and mediterranean climatic areas with winter rainfall.