Analysis of Genetic Relationships and Antimicrobial Susceptibility of Verotoxin-Producing Escherichia coli Strains Isolated in Nagasaki Prefecture,Japan in 1996

A total of 19 Escherichia coli O157 isolates were obtained in Nagasaki Prefecture, in the southwestern part of Japan, between 1990 and 1996. Pulsed-field gel electrophoresis (PFGE) and computer-assisted analysis were applied to determine genetic relationships among these strains. Fragment patterns of the isolates in Nagasaki, as determined by PFGE, were compared with those of isolates in other areas where large outbreaks and sporadic cases of E. coli O157 infection occurred. Similarity values of all the strains isolated in Nagasaki Prefecture were over 0.65 except for E. coli O26. Some strains were identical to the strains isolated from the areas where large outbreaks occurred. All strains were susceptible to ampicillin, fosfomycin, minocycline, amikacin, ofloxacin and sulfamethoxazole-trimethoprim.     

The photoconversion of heat-treated Chenopodium chlorophyll protein and its pH dependence

Photosensitive Chenopodium chlorophyll protein was purifiedby warming the complex in a boiling water bath, followed bypassing it through a Sephadex column. The shape and positionof the absorption band in the absorption spectrum of purifiedchlorophyll protein (HCP668) were the same as those of non-treatedchlorophyll protein (CP668), except for a change in the proteinband in the UV region. The chlorophyll protein retained a quarterof its original photoconvertibility after heat treatment for25 min at 100°C. Results suggested that the chlorophyll-aminoacid residue binding is very stable against heat, and that chlorophyllis protected from decomposition through the rigid binding. The photoconvertibility of HCP668, as well as CP668, dependedstrongly upon pH, with a pronounced decrease below pH 4 andabove pH 6. Optimal convertibility was at pH 5. Above pH 12,convertibility vanished completely. However, pH-inhibited convertibilityof HCP668 was recovered to its original level by returning thepH to neutral. Illuminalion of CP668 in D₂O with red light caused a markedincrease in light scattering. This reveals the occurrence ofa conformational change of apoprotein, leading to aggregation. HCP668 was degraded by mechanical treatment to give a smallersized photosensitive chlorophyll protein without loss of photoconvertibility.This small chlorophyll protein did not precipitate in a saturated(NH₄)₂SO₄ solution. The spectral properties of this complexwere identical to those of HCP668 and CP668. (Received March 21, 1972; )     

Electron microscopic study on the initiatory cell-activation of procambium at commencement of germination in radish cotyledons

Most fine structural studies of seed germination have been begun at 24 hr after imbibition of water and lasted for several days. However, studies on the initial period beginning with water uptake are few. In the present study, fine structural changes in radish seed cotyledonal tissues which occur within the first 24 hr of germination were investigated. Remarkable morphological and developmental changes of the cell organelles were profound in procambial cells in a matter of hours, while no cytological changes were noticed yet in mesophyll (storage tissue) cells. The endoplasmic reticulum and Golgi bodies were somewhat proliferated, a rapid development even, of proplastids occurred, and the increment of mitochondria in numbers and profiles were particularly noteworthy. From these observations, it was interpreted that, although the procambium accounts for only a small portion of the cotyledons, the initiatory activation of procambial cells, being sensitive to the starting of water uptake, might provide certain facility for leading the activation of the more lethargic storage tissue in the beginning of germination process.