An Improved Enrichment Broth for Isolation of Escherichia coli O157, with Specific Reference to Starved Cells, from Radish Sprouts

An enrichment broth was developed for the efficient isolation of Escherichia coli O157 from radish sprouts. The broth was buffered peptone water containing 0.5% sodium thioglycolate (STG-BPW), which was designed to allow growth of E. coli O157 in starved and unstarved states. However, this medium suppressed the growth of non-carbohydrate-fermenting obligate aerobes whose colonial appearance on sorbitol MacConkey agar containing cefixime and tellurite (CT-SMAC) resembled that of E. coli O157. Both starved and unstarved cells of E. coli O157 experimentally inoculated into radish sprouts were successfully recovered with STG-BPW enrichment in all cases, most of which showed marked disappearance of E. coli O157-like colonies on CT-SMAC.     

An envelope-shaped film culture vessel for plant cell suspension cultures and metabolite production without agitation

An envelope-shaped film culture vessel (named Culture Bag) made of fluorocarbon polymer film, which is much more permeable to oxygen, nitrogen and carbon dioxide than other films, was found to be suitable to grow plant cells in liquid medium without agitation. Proliferous BY-2 tobacco cells showed almost the same growth in a Culture Bag of 12.5 m-thick film as that in a shake flask; the growth was lower in a Culture Bag of a thicker film. Lithospermum erythrorhizon cells produced almost the same amount of red naphthoquinone pigments (shikonin derivatives) in a Culture Bag of 12.5 m-thick film as those in a shake flask although the productivity was suppressed as the film thickness increased. L. erythrorhizon cells in a Culture Bag produced much less abnormal stress metabolites (orange-colored benzoquinone derivatives) than those in a shake flask, suggesting that culturing cells in the Culture Bag was less stressful due to its stationary liquid environment.     

DIVERSITY OF HALOGENATED SECONDARY METABOLITES IN THE RED ALGA LAURENCIA NIPPONICA (RHODOMELACEAE,CERAMIALES)1,2

Many morphologically similar, but chemically distinct, populations have been found in the marine red alga Laurencia nipponica Yamada (Rhodomelaceae, Ceramiales) growing in Japan. Each chemical type is characterized by a specific end-product of halogenated secondaly metabolite synthesis: chamigrane-type sesquiterpenoids such as prepacifenol and halochamigrene epoxide and C₁₅ bromoethers such as laurencin, laureatin, isoprelaurefucin, epilaurallene, and kumausallene. These seven types of secondary metabolite syntheses remained the same in the wild and under various culture conditions. Because bromoethers and terpenoids are probably synthesized by different metabolic pathways, it is virtually certain that different sets of enzymes participate in their synthesis. Prepacifenol- and laureatin-producing populations were selected as representatives of terpenoid and bromoether groups, respectively. F₁ tetrasporophytes derived from crosses between reciprocal, female and male gametophytes of prepacifenol- and laureatin-producing strains bore both types of metabolites, suggesting that the genes Producing these enzyme systems are encoded by nuclear genomes. The F₁ gametophytes resulting from the reciprocal crosses produced either prepacifenol or laureatin, and the four individuals derived from spore tetrads (a set of tetraspores derived from a single tetrasporangium) produced either prepacifenol or laureatin in a 1:1 ratio, indicating that genes participating in terpenoid synthsis and those participating in bromoether synthesis are on different loci of homologous chromosomes and are segregated at meiosis (tetrasporogenesis). One individual of this interpopulational F₁ gamtophyte produced both parental types of metabolite, perhaps indicating the occurrence of a recombination type. Natural hybrid individuals, including such recombination-type gametophytes, were found in a sympatric locality at which these two chemical types occur. F₁ tetrasporophytes derived from crosses between respective prepacifenol- and laureatin-producing strains and their F₁ gametohytes produced only parental-type metabolite-producing plants. These results indicate that the diverse chemical types can be referred to as races (chemical races).     

Comparative reproductive patterns in culture of differentGigartina subgenusMastocarpus andPetrocelis populations from northern Japan

Samples of theGigartina pacifica-ochotensis complex were collected at 21 localities around Hokkaido and northern Honshu. The carpospore and blade tip cultures showed 3 reproductive patterns. (1) 237 (86.8%) of the 273 cultured isolates derived from single plants have a direct type of life history. (2) 29 (10.6%) isolates exhibited a heteromorphic type with the alternation of foliose gametophytes and crustose tetrasporophytes. (3) 7 (2.6%) isolates showed a mixed pattern in which carposporelings developed intoPetrocelis-like crusts, basal discs with uprightGigartina blades, or chimera-like discs with compositePetrocelis-Gigartina anatomy. CulturedGigartina blades derived from bothG. pacifica andG. ochotensis were similar in morphology. In 18 cultures from 5 localitiesPetrocelis tetraspores developed into dioeciousGigartina gametophytes. A single tetrasporeling grew into aGigartina plant that reproduced directly. In hybridization experiments with 8 male and 14 female isolates from 4 localities on Hokkaido 85 (78.0%) of 109 were positive. On the basis of these and earlier studies it is concluded that a single species is present in northern Japan:G. pacifica Kjellm. has priority overG. ochotensis (Rupr.) Rupr. ex Yendo.     

Properties of membrane-bound α-glucosidases: Possible sugar receptor protein of the blowfly, Phormia regina

Previously reported PII-type α-glucosidase located in the precipitate of the labellar homogenate of the blowfly Phormia regina was solubilized by sodium deoxycholate (DOC) and further separated into three isozymes with different molecular weight: PII-M (mol. wt 9 × 10⁴). PII-D (mol. wt 2 × 10⁵) and PII-T (mol. wt 8 × 10⁵) by molecular sieve chromatography on Biogel P-300 or Ultragel AcA-34. These three isozymes had almost the same K_m's and relative values of V_m's for several substrates, suggesting that they had the same common active site.PII-D and PII-T are more strongly embedded in the membrane than PII-M, because the proportion of PII-D and PII-T was much increased when the remaining glucosidase in the precipitate after the first solubilization was reextracted by DOC. A large peak of α-glucosidase isozyme P-IV which preferentially hydrolyze sucrose eluted just after P-II (soluble P-II) when the supernatant fraction of the labellar homogenate was chromatographed on DEAE-Sephadex A-50. P-IV was scarcely present in the precipitate fraction.Soluble P-II had the same mol. wt as PII-M and had similar properties to PII-M except for the ratio of V_m's.A large proportion of PII-D was contained in the well washed labellar integuments, a preparation rich in labellar chemosensilla. It suggests that most of the insoluble α-glucosidase contained in the dendrite in labellar chemosensilla is PII-D. PII-D (and PII-T) are possible sites of the pyranose receptor molecule because their properties and localization agree well with those of the receptor.     

Germitorosone and methylgermitorosone,two hydroanthracene derivatives from seedlings of Cassia torosa

Two new yellow pigments, germitosone and methylgermitorosone, were isolated from the seedling of Cassia torosa. The structures of these substances were established as 3,7 dimethyl - 6 - methoxy - 1 - oxo - 2,3,8,9 - tetrahydroxy - 1,2,3,4 - tetrahydroanthracene and 6,9 dimethoxy - 3,7 - dimethyl - 1 - oxo - 2,3,8 - trihydroxy - 1,2,3,4 - tetrahydroanthracene respectively.     

Regulation of the production of the agglutination substances responsible for sexual agglutination in Saccharomyces cerevisiae: Changes associated with conjugation and temperature shift

Summary Isolated zygotes showed self-agglutination caused by the sex-specific glycoproteins, the agglutination substances responsible for sexual agglutination. The agglutination substances of both a and mating types were detected in the extracts obtained by the autoclave method from zygotes. Although the first diploid daughter cells from zygotes showed self-agglutinability, the self-agglutinability decreased gradually in the successive diploid daughter cells. The self-agglutination in diploid cells was also brought about by the complementary binding of the sex-specific agglutination substances of opposite mating types.The constitutive sexual agglutinability in a and cells was lost with concomitant loss of the agglutination substances in both cell wall and cytoplasmic fractions when cultured at a temperature higher than 35°C.The repression of the production of the agglutination substances was reversed by the opposite mating type pheromones even at the repressive temperature, 36°C, associated with the appearance of sexual agglutinability. The sex pheromones, a substance-I and substance-I, and the binding substance for substance-I were produced even at 36°C, repressive for the production of the agglutination substances.     

A probable lack of function of c-type cytochrome in the photosynthetic system of the blue-green alga Anabaena variabilis

Quantitative study of the cytochrome c acting in the photosyntheticsystem of the blue-green alga Anabaena variabilis (M-2) wasdone with membrane fragments and intact cells. Membrane fragments highly active in the NADP⁺-Hill reaction(above 200 µmoles/mg chl.a;-hr) retained photoresponsivecytochrome c equal only one-tenth that of P700, while the plastocyanincontent was almost equal to that of P700. The cytochrome contentin intact cells was a little larger than that in membrane fragmentson the chlorophyll a basis. However, the values relative toP700 (1/9) and plastocyanin (1/10) were identical with thosein membrane fragments. The content was also far smaller thanthat of reaction center II's (1/6). If the cytochrome mediatesall electrons from reaction center II, the cytochrome oxidation-reductionshould have a rate constant of 2.4?102 sec^–1 which isone order above of the rate constant of the cytochrome reduction(2.3 to 3.5?10¹sec^–1). These quantitative relationshipsindicate that in Anabaena variabilis (M-2), c-type cytochrome,either cytochrome f or algal cytochrome c, cannot function inthe main electron flow between two reaction centers. (Received September 8, 1978; )     

Studies on Thin-Layer Chromatography after Incubation with [35S]Methionine as an Aid to Identification of Mycobacteria

Thin-layer chromatography (TLC) of ethyl ether-ethanol extracts of mycobacteria obtained after incubation with [³⁵S] methionine is useful for differentiation among mycobacterial species, as the distribution of radioactive spots in TLC shows a characteristic pattern except for a few species, including M. intracellulare and M. gordonae. Some supplementary studies have been carried out in the present investigation and the following results have been obtained.

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