A putative GDP–GTP exchange factor is required for development of the excretory cell in Caenorhabditis elegans

The Caenorhabditis elegans excretory cell extends tubular processes, called canals, along the basolateral surface of the epidermis. Mutations in the exc-5 gene cause tubulocystic defects in this canal. Ultrastructural analysis suggests that exc-5 is required for the proper placement of cytoskeletal elements at the apical epithelial surface. exc-5 encodes a protein homologous to guanine nucleotide exchange factors and contains motif architecture similar to that of FGD1, which is responsible for faciogenital dysplasia. exc-5 interacts genetically with mig-2, which encodes Rho GTPase. These results suggest that EXC-5 controls the structural organization of the excretory canal by regulating Rho family GTPase activities.     

Analysis of common antigen of flagella in Bacillus cereus and Bacillus thuringiensis

Abstract Flagellar antigen of Bacillus cereus H.1 was purified and tested for serodiagnostic antigen by ELISA. The antibody against the flagellar antigen of B. cereus H.1 reacted not only with the homologous specific antigen but also reacted with the flagellar antigens of 23 strains of B. cereus . This common flagellar antigen of B. cereus was found to be due to 61-kDa protein by SDS-PAGE and immunoblot assay. Monoclonal antibody H15A5 against common antigenic epitope of B. cereus also reacted with flagellar antigens of 21 strains of Bacillus thuringiensis by ELISA. This monoclonal antibody reacted with the 61-kDa protein of the flagella of B. cereus H.1 and H.2 and B. thuringiensis Kurstaki HD1, Alesti and Aizawai juroi by immunoblot analysis. These results indicated that the common antigenic epitope of the 61-kDa protein existed in the flagella both of B. cereus and B. thuringiensis .     

Reconstitution and Characterization of H+-Translocating ATPase from the Plasma Membrane of Phaseolus mungo L. Roots

Plasma membrane H⁺-translocating ATPase was partially purifiedfrom mung bean (Phaseolus mungo L.) roots and reconstitutedinto soybean phospholipid (asolectin) liposomes by the n-octylglucosidedilution method. The resulting proteoliposomes were mainly unilamellarvesicles ranging in size from 0.05 to 0.2 µm. The existenceof ATP-drived H⁺-pumping across the proteoliposomes was demonstratedby the quenching of quinacrine fluorescence in the presenceof Mg²⁺. The quenching could be abolished by an uncoupler, FCCP,and an inhibitor of H⁺-translocating ATPase, vanadate. The reconstitutedATPase consisted of three major polypeptides of 105 KDa, 67KDa and 57 KDa. Its pH optimum, divalent cation stimulationand vanadate sensitivity were similar to those of partiallypurified ATPase. However, the specificity toward ATP was muchgreater following reconstitution. Also reconstitution reducedthe degree of inhibition by DCCD. Local anesthetics (e.g. dibucaine)had no effect on H⁺-pumping activity but increased the ATPaseactivity when proteoliposomes were reconstituted in their presence. (Received May 2, 1986; Accepted October 17, 1986)     

Filtering rates on natural bacteria by Daphnia longispina and Eodiaptomus japonicus in Lake Biwa

Filtering rates on [³H]thymidine-labelled natural unattachedbacteria and that on [¹⁴C]bicarbonate-labelled natural planktonwhich pass through the 25 µm-mesh-size screen were measuredfor Daphnia longispina and Eodiaptomus japonicus in Lake Biwa.Errors associated with the radioisotope technique, i.e the lossof labels after feeding trials and the self-absorption of thebeta emittance of ³H, were checked and corrected for the calculationof the filtering rates. It was suggested that Daphnia collectsbacteria efficiently, although the efficiency is somewhat variabledepending on food particle composition (i.e. presence and absenceof larger particles) and feeding condition (i.e. animal densityand physical disturbance). By contrast, copepodites of Eodiaptomuswere suggested to be less efficient bacteria feeders. Food resourceexploitation strategies of these two co-existing zooplanktersare discussed.     

Response of Tonoplast and Plasma Membrane ATPases in Chilling-Sensitive and -Insensitive Rice (Oryza sativa L.) Culture Cells to Low Temperature

Tonoplast and plasma membrane vesicles were prepared from chilling-sensitive(CS) and chilling-insensitive (CI) cultured cells of rice (Oryzasativa L.) to examine how they would respond to low temperature.With CS cells, the specific activity of ATPase in tonoplastvesicles was relatively higher than that of plasma membraneATPase. Tonoplast ATPase activity was decreased by low temperaturetreatment, and a slight decrease in plasma membrane ATPase activitywas also observed. The decrease in the specific activity ofthe tonoplast ATPase by low temperature may reflect a decreasein V_max. However, no change was noted in K_m. The break pointof the Arrhenius plots of the tonoplast ATPase was ca. 32?C,this value being ca. 9?C higher than that of the plasma membraneATPase. With CI cells, the specific activity of tonoplast ATPasewas somewhat less than that of the plasma membrane ATPase. TonoplastATPase activity was decreased by low temperature at 5?C, whereasan increase in plasma membrane ATPase activity was observed.The break point of the tonoplast ATPase activity was ca. 22?C,which was 3?C higher than that of the plasma membrane ATPase.Using ATPase solubilized from the plasma membrane or tonoplast,the Arrhenius plots of log ATPase activity against the reciprocalof absolute temperature gave a straight line fit from 5?C to45?C with no obvious break point. The break point appeared onadding a phospholipid mixture (asolectin) to a reaction mixturecontaining solubilized enzyme. The slope of the curve of theArrhenius plot was very different between the CS and CI cells.The plasma membrane and tonoplast ATPases from the CS cellshad a higher E_a above 20?C, whereas that from the CI cells hada lower one. These findings indicate that the tonoplast ATPase in a riceplant is more sensitive to low temperature than the plasma membraneATPase, with this response possibly being due to interactionsbetween the proteins and phospholipids. (Received January 6, 1988; Accepted July 5, 1988)     

Effects of chronic bifemelane hydrochloride administration on receptors for N-methyl-d-aspartate in the aged-rat brain

We assayed N-methyl-d-aspartate (NMDA) receptors [³H]3-(2-carboxypiperazin-4-yl)propyl-1-phosphonic acid ([³H]CPP) bindings) and evaluated their distribution in the brain by quantitative autoradiography in young adult and aged rats. In the young adult rats, NMDA receptors were present at relatively high concentrations in the cerebral cortex and hippocampus. In the aged rats, NMDA receptors were decreased in the nealy all areas of the brain, especially in the cerebral cortex and hippocampus. Chronic administration of bifemelane hydrochloride, a drug for sequela of cerebrovascular diseased, at a dose of 15 mg/kg/day for 14 days, markedly attenuated these decrease in NMDA receptors. Since NMDA receptors are considered to be involved in memory and learning processes, our results suggest that bifemelane hydrochloride may be applicable to the treatment of disturbed memory and learning.     

Molecular cloning of the gene coding for the human T cell differentiation antigen CD7

The CD7 molecule is a differentiation antigen found on the surface of T lymphocytes and also on a very minor fraction of acute nonlymphocytic leukemia (ANLL). To study the genomic structure of the CD7 gene, two clones (SY4 and SY22) were isolated by screening a genomic library with a CD7 cDNA probe. Restriction mapping of these two phage clones showed that both overlapped each other, covering a total length of 23 kilobases (kb). Transfection of mouse L cells demonstrated that SY22 contains the gene expressing the CD7 antigen reactive with monoclonal CD7 antibody (Tp40), while SY4 does not. Subcloning of a 10.5 kb fragment from a 14.4 kb insert of SY22 contained the structural gene for the CD7 antigen. Detailed restriction mapping and partial sequence analysis revealed the CD7 gene to consist of four exons. By RNase protection assay, multiple initiation sites — 122 base pairs (bp) to — 38 bp from ATG translation initiation site were demonstrated. The promoter region had high G+C content and contained two SP1 binding sites (CCGCCC) and an AP2 binding site (CCCCAGGC), but lacked CAAT and TATA motifs.     

Effect of maximal arm exercise on skin blood flux in the paralyzed lower limbs in persons with spinal cord injury

The purpose of the present study was to examine the effect of maximal arm exercise on the skin blood circulation of the paralyzed lower limbs in persons with spinal cord injury (PSCI). Eight male PSCI with complete lesions located between T3 and L1 performed graded maximal arm-cranking exercise (MACE) to exhaustion. The skin blood flux at the thigh (SBFT) and that at the calf (SBFC) were monitored using laser-Doppler flowmeter at rest and for 15 s immediately after the MACE. The subject's mean peak oxygen uptake and peak heart rate was 1.41 ± 0.22 1·min⁻¹ and 171.6 ± 19.2 beats·min⁻¹, respectively. No PSCI showed any increase in either SBFT or SBFC after the MACE, when compared with the values at rest. These results suggest that the blood circulation of the skin in the paralyzed lower limbs in PSCI is unaffected by the MACE.