Refined genetic analysis of the region II che mutants in Salmonella typhimurium

Summary From a detailed complementation analysis of the region II che mutants of Salmonella typhimurium, we have located five che genes, cheA, cheW, cheR, cheB, and cheY. We have shown that corrections are required in the previous assignment of the mutations in four strains: both SL2514 and SL2515 which have been reported to be cheY mutants are cheR mutants, SL2539 is not a cheA but a cheW mutant, and ST171 which has been reported to be a cheZ mutant is a double mutant with defects in both cheA and cheB. Since ST171 is the only cheZ mutant so far isolated, the idea that the cheZ gene might play an essential role in chemotaxis in S. typhimurium as in Escherichia coli has lost its experimental basis. Furthermore, a number of deletion mutants in region II resulting from the excision of Tn10 have been isolated and analysed. From these experiments, we propose that the gene order in region II is flaK-flaE-motA-motB-cheA-cheW-cheR-cheB-cheY-flaM-flaC, which is identical with that in E. coli.     

Inhibitory ca2+-control of movement of beads coated withphysarum myosin along actin-cables inChara internodal cells

Summary The actin-activated ATPase activityPhysarum myosin was shown to be inhibited of M levels of Ca²⁺. To determine if Ca²⁺ regulates ATP-dependent movement ofPhysarum myosin on actin, latex beads coated withPhysarum myosin were introduced intoChara cells by intracellular perfusion. In perfusion solution containing EGTA, the beads moved along the parallel arrays ofChara actin filaments at a rate of 1.0–1.8 m/sec; however, in perfusion solution containing Ca²⁺, the rate reduced to 0.0–0.7 m/sec. The movement of beads coated with scallop myosin, whose actin-activated ATPase activity is activated by Ca²⁺, was observed only in the perfusion solution containing Ca²⁺, indicating that myosin is responsible for the inhibitory effect of Ca²⁺ onPhysarum myosin movement. The involvement of this myosin-linked regulation in the inhibitory effect of Ca²⁺ on the cytoplasmic streaming observed inChara internodal cell andPhysarum plasmodium was discussed.Abbreviations ATP adenosine 5-triphosphate - DTT dithiothreitol - EDTA ethylenediaminetetraacetic acid - EGTA ethyleneglycolbis(-aminoethylether) N,N,N,N-tetraacetic acid - PIPES piperazine-N,N-bis(2-ethanesulfonic acid)     

Continuous production of galacto-oligosaccharides from lactose using immobilized β-galactosidase from Bacillus circulans

Summary -Galactosidase-2 (-d-galactoside galactohydrolase, EC 3.2.1.23) from Bacillus circulans was purified using hydroxyapatite gel chromatography and immobilized onto Duolite ES-762 (phenolformaldehyde resin) and Merckogel (controlled pore silica gel) for continuous production of galacto-oligosaccharides using lactose as the substrate. The maximum amount of ologosaccharides produced by the immobilized enzyme was 35–40% of the total sugar during hydrolysis of 4.56% lactose. Partially purified -galactosidase from B. circulans was also immobilized onto various supports for the same purpose. The stability of the immobilized -galactosidase-2 or partially purified enzyme during a continuous reaction depended on their supports and specific activity. Of the supports tested, Merckogel was best for operational stability. With this support, the enzyme was quite stable with specific activity up to 15 units/g of wet gel; it was reversibly inactivated with more.     

Increase in the activity of Rhizopus delemar lipase on water-soluble esters by its binding with phosphatidylcholine

Rhizopus (Rh.) delemar (ATCC 34612) C-lipase was found to exhibit a slight activity towards water-soluble esters. The hydrolytic reaction of this lipase on alpha-naphthyl acetate was competitively inhibited by the presence of olive oil or Tween 80. This finding showed that both substrates, insoluble triglyceride and water-soluble ester, were hydrolyzed at the same site on the enzyme. The activities on water-soluble esters (alpha-naphthyl acetate, beta-naphthyl acetate, methyl acetylsalicylate and Tween 80) increased on binding of lipase with phosphatidylcholine (PC), although the activity on olive oil did not change. The increase in activity on water-soluble esters was due to the increase in the Vmax for its hydrolysis. It appears that local structural change of the catalytic site on lipase occurred on binding of PC to the lipase molecule and resulted in an increase in the activity on water-soluble esters. The temperature dependence of the hydrolysis of water-soluble esters demonstrated that the activation energy was lowered on binding of PC to the lipase molecule, and this resulted in an increase in the activity.     

Development of the bitterling,Paracheilognathus himantegus (Cyprinidae), with a note on minute tubercles on the skin surface

The development of the eggs and larvae and minute tubercles on the skin surface ofParacheilognathus himantegus larvae were observed. The egg began to hatch approximately 68 hours after insemination and the larvae reached the free-swimming stage 23 days after hatching at water temperature of 22±1°C. The larval development and minute tubercles on the skin surface of this species were similar to those ofAcheilognathus lanceolata, A. limbata, A. signifer andTanakia tanago. However, the shape of the ripe eggs ofP. himantegus differed from those of the four species. As regards the shape of eggs, there was a common characteristic amongP. himantegus, Rhodeus uyekii andA. limbata from Korea. As regards larval development,P. himantegus had two characters also found inRhodeus. These facts seem to suggest thatP. himantegus is closely related toA. lanceolata, A. limbata, A. signifer andT. tanago but is more specialized than these four species, except forA. limbata from Korea.     

Identification of viruses infected in Rehmannia glutinosa Libosch. var purpurea Makino and effect of virus infection on root yield and iridoid glycoside contents

Virus free plants of Rehmannia glutinosa Libosch. var. purpurea Makino were obtained through meristem tip tissue cultures from plants infected with a mixture of tabocco mosaic virus(TMV), a member of the carlavirus group, and an unknown spherical virus. The re-infection rate of the virus free plants by TMV in the field was determined by enzyme linked immunosorbent assay(ELISA). Twenty seven percent of the plants were re-infected during the first year, 31 % by the end of second year, and 63 % by the end of the third year. The yield of root and iridoid glycoside contents gradually decreased each year. These results led to the conclusion that virus infection causes marked decrease of the yield of roots and productivity of secondary metabolites.     

Fine structure of neurons synthesizing vasoactive intestinal peptide in the human colon from patients with Hirschsprung's disease

Summary The fine structure of neuronal perikarya and processes containing VIP-like immunoreactive material in the colon of patients with Hirschsprung's disease was investigated by immunoelectron microscopy. No VIP-like immunoreactive terminals were found in Auerbach's plexus of the ganglionic segment. However, VIP-like immunoreactive preterminal axons were frequently found to make synaptic contact with both immunoreactive and non-immunoreactive elements within Meissner's plexus. Therefore, the function of the VIP neurons in Auerbach's plexus seems to differ from that in Meissner's plexus. In the oligoganglionic segment, there were a few VIP-like immunoreactive processes, but no VIP-like immunoreactive synaptic formations. VIP-like immunoreactive processes were rarely encountered in the aganglionic segment. In both the oligo-and aganglionic segments, bowel relaxation is considered to be disturbed due to the lack of synaptic contacts of VIP-like immunoreactive neurons with other neuronal components.This work was supported in part by a grant (no. 57370002) from the Ministry of Education, Science and Culture, Japan     

Electron-microscopic immunocytochemistry of neuropeptide Y immunoreactive innervation of vasopressin neurons in the paraventricular nucleus of the rat hypothalamus

The neuropeptide Y (NPY) immunoreactive synaptic input to neurons containing neurophysin II (NP II), the carrier protein of vasopressin (VP), was observed in the paraventricular nucleus (PVN) of the rat hypothalamus by double-labeling immunocytochemistry combining the preembedding peroxidase-antiperoxidase (PAP) method with the postembedding immunogold staining method at the electron-microscopic level. NPY-like immunoreactivities were detected by the PAP method in the dense granular vesicles (70-100 nm in diameter) in the immunoreactive presynaptic axon terminals. NP II-like immunoreactive large neurosecretory granules labeled with gold particles were found in the neurons receiving synaptic input of the NPY-like immunoreactive terminals. This suggests that NPY may be a neurotransmitter or neuromodulator and that NPY neurons may, through synaptic contacts, regulate the secretion of VP neurons.