Growth Medium Containing Cyclodextrin and Low Concentration of Horse Serum for Cultivation of Helicobacter pylori

The growth of Helicobacter pylori, a Gram-negative microaerophilic bacterium, is often difficult and requires complex media with the supplementation of 5% to 10% blood or blood derivatives. We have found that Brucella broth supplemented with 1% heated horse serum and 0.1% β-cyclodextrin supports the good growth of H. pylori. The degree of growth and production of urease and vacuolating cytotoxin in this medium were equal to those in the medium supplemented with 5% horse serum. This medium was found to be suitable for both the routine laboratory culture and primary isolation of H. pylori from biopsy samples.     

Imprint of post-glacial history in a narrowly distributed endemic spruce, Picea alcoquiana, in central Japan observed in nuclear microsatellites and organelle DNA markers

Aim We aim to infer the post‐glacial history of the narrowly distributed endemic spruce Picea alcoquiana in Japan, and to assess the hypothesis that the existing narrow natural range of the species has resulted from the diminution of the past natural range since the last glacial period. Location Mountainous forests in central Honshu Island in Japan. Methods We assessed the geographical patterns of genetic variation across nine populations of P. alcoquiana across its natural range using five nuclear microsatellites and polymerase chain reaction–restriction fragment length polymorphism markers for chloroplast (cp) and mitochondrial (mt) DNA. This study focuses on the genetic differentiation between northern peripherally isolated and southern core populations within the natural range of the species in central Honshu. In addition, based on diagnostic morphological traits of the cone, we used reliable macrofossil evidence to gain further insight into the past natural range of the species. Results Picea alcoquiana shows a level of genetic differentiation among populations (Φ_ST = 0.082) that was higher than the levels observed in nuclear microsatellites for other anemophilous and widespread tree species in Japan. A notable finding for the nuclear microsatellites was the loss of rare alleles and strong evidence of a recent bottleneck in the peripherally isolated populations. Analysis of molecular variance in cpDNA and mtDNA markers showed an absence of genetic differentiation between the peripherally isolated and core populations. Macrofossil evidence indicated that the past natural range of the species extended to a lower elevation and c. 135 km north of the existing peripherally isolated populations during the last glacial period (c. 28,000 yr bp ). Main conclusions During the last glacial period, P. alcoquiana had a wider natural range in which the peripherally isolated and core populations could have been geographically continuous with each other, and effective gene flow by means of pollen and seeds might have occurred. The recent bottleneck and consequent loss of rare alleles in the peripherally isolated populations might have evolved during the diminution and retreat of the northern part of the past natural range southwards to the core area and during the subsequent separation of the peripherally isolated populations from the core area since the last glacial period.     

Cytosolic Aconitase Participates in the Glyoxylate Cycle in Etiolated Pumpkin Cotyledons

Two different aconitases are known to be expressed after thegermination of oil-seed plants. One is a mitochondrial aconitasethat is involved in the tricarboxylic acid cycle. The otherparticipates in the glyoxylate cycle, playing a role in gluconeogenesisfrom stored oil. We isolated and characterized a cDNA for anaconitase from etiolated pumpkin cotyledons. The cDNA was 3,145bp long and capable of encoding a protein of 98 kDa. N-terminaland C-terminal amino acid sequences deduced from the cDNA didnot contain mitochondrial or glyoxysomal targeting signals.A search of protein databases suggested that the cDNA encodeda cytosolic aconitase. Immuno blotting analysis with a specificantibody against the aconitase expressed in Escherichia colirevealed that developmental changes in the amount of the aconitasewere correlated with changes in levels of other enzymes of theglyoxylate cycle during growth of seedlings. Further analysisby subcellular fractionation and immunofluorescence microscopyrevealed that aconitase was present only in the cytosol andmitochondria. No glyoxysomal aconitase was found in etiolatedcotyledons even though all the other enzymes of the glyoxylatecycle are known to be localized in glyoxysomes. Taken together,the data suggest that the cytosolic aconitase participates inthe glyoxylate cycle with four glyoxysomal enzymes. (Received December 1, 1994; Accepted March 17, 1995)     

Heterologous Expression and Subcellular Localization of Pumpkin Seed Tonoplast Intrinsic Proteins (TIP) in Yeast Cells

Two tonoplast intrinsic proteins (TIP) of pumpkin seeds, pMP23and MP28, were expressed in yeast cells under control of theGAL1 promoter, and the subcellular localization of the proteinswas analyzed. The pMP23 and MP28 stably accumulated in the yeastvacuolar membrane when the proteins were expressed in the proteinaseA-deficient strain (pep4), which lacks the activities of vacuolarproteases. However, pMP23 and MP28 did not accumulate in thewild-type strain; the expressed pMP23 and MP28 were degradedin a proteinase A-dependent manner. These results indicate thatpMP23 and MP28 are transported to the vacuolar membrane whenexpressed in yeast. ⁵Present address: Department of Biochemistry and Molecular Biology,The Pennsylvania State University, University Park, PA16802,U.S.A.     

Competition between two congeneric stream gobies for habitat in southwestern Shikoku, Japan

Competition between two congeneric gobies, Rhinogobius sp. LD (large-dark type) and CB (cross-band type), for habitat was studied in a tributary of the Shimanto River, southwestern Shikoku, Japan. Habitat use by CB, measured by water depth, current velocity, and substrate, was compared between before and after the removal of LD. After the removal of LD, CB shifted their habitat use to coarser substrates than previously, suggesting a release from effects of LD. This result supports a hypothesis from our previous study that habitat partitioning between CB and LD is a consequence of interference effects of LD on CB.     

Polarization of membrane glycoproteins during monocyte chemotaxis

Distribution of membrane glycoproteins was studied in chemotactic monocytes using ferritin-conjugated lectins. The cells became polarized forming a pseudopodia at a leading head. Membrane glycoproteins were redistributed at the head. This phenomenon was not observed in chemokinetic or non-chemotactic cells suggesting that membrane glycoproteins may have a role in recognition of the chemoattractant.