Escherichia coli uvrD mutants with thermosensitive DNA-dependent adenosine triphosphatase I (helicase II)

Three mutants producing thermosensitive DNA-dependent Adenosine triphosphatase (ATPase) I were screened from a collection of temperature-sensitive mutants of Escherichia coli K12. ATPase I purified to near homogeneity from one of the mutants (JE11000) possesses both thermosensitive DNA-dependent ATPase and DNA helicase activities. We have shown that ATPase I is encoded by the uvrD gene as first suggested by Oeda et al. (1982): (i) the thermosensitive ATPase I mutation present in JE11040 lies in or very close to the uvrD gene, (ii) ATPase I activity is absent in uvrD210, uvrD156, and uvrD252 mutants. Thus the thermosensitive mutations correspond to new uvrD mutations. However, the mutation present in JE11040 confers neither UV sensitivity nor mutator phenotype at high temperature. Evidence is presented that the mutant ATPase I is stabilized in vivo at 42 degrees C.     

Effect of TPA on the mutagenicity of caffeine in the soybean mutation test

12-O-Tetradecanoylphorbol-13-acetate (TPA) is a well-known tumor promoter in mouse-skin carcinogenesis. Its effects on mutagenesis in a soybean test system were examined, and the effects were judged from the appearance of spots of various colors on the leaves. When soybean seeds were treated with TPA plus 0.03% caffeine, the frequency of spots per leaf decreased significantly and in proportion to the concentration of TPA. TPA alone at concentrations of 1–20 μg/ml did not induce any mutations. Mutations induced by γ-rays were not affected by administration of TPA either before or after exposure to γ-rays. The mechanism of suppression by TPA of mutations induced by caffeine is discussed.     

Impaired Transduction of R213 and Its Recovery by a Homologous Resident R Factor

Transduction by Plkc of drug-resistance markers of the factor R213 was shown to occur at an exceptionally low frequency (at less than 10(-8) of the input phage), and they could not be transduced by P22. When the recipient cells carried a homologous R factor derived from R213, markers were transduced by Plkc at a normal frequency (at about 10(-5) to 10(-6) of the input phage). Derivative R factors, transducible by Plkc at a normal frequency but being transferred by conjugation at a frequency lower than that of the original R213, were obtained. This type of transductant often segregated R(-) cells. In addition, several transductants contained R factors which were transferred normally by conjugation but were transduced by Plkc at as low a frequency as the original R213. This type of transductant was an effective recipient for transduction by Plkc of R213 when apparently "cured" by acridine treatment. No such effective "cured" recipients were obtained from the transductants with derivatives of R213 transducible at a normal frequency. Two possible interpretations are presented: (i) R213 produces a bacteriocin-like substance upon transduction, or (ii) the genome size of R213 is too large for all of its determinants to be transduced.     

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.     

Histochemical demonstration of O-glycosidically linked,type 3 based ABH antigens in human pancreas using lectin staining and glycosidase digestion procedures

Summary Histochemical analyses of the chemical structures of sugar sequences with or without blood group specificity were carried out by combined stepwise digestion of tissue sections with exo-and endoglycosidases and subsequent lectin stainings in formalin-fixed, paraffin-embedded human pancreas. In acinar cells from blood group A or AB secretor individuals, sequential digestion with -N-acetylgalactosaminidase and -L-fucosidase imparted reactivity with peanut agglutinin (PNA) in cells reactive with Dolichos biflorus agglutinin as well as those with Ulex europaeus agglutinin I(UEA-I). Simple fucosidase digestion imparted the PNA reactivity only in UEA-I reactive cells. Sequential digestion with -galactosidase and fucosidase likewise liberated the PNA binding sites in Griffonia simplicifolia agglutinin I-B₄ reactive cells from blood group B and AB secretors. Sialidase digestion liberated the PNA binding sites not only in acinar cells but also intercalated duct cells, islet cells of Langerhans and endothelial cells. The PNA reactivity obtained by these enzyme digestions was eliminted by endo--N-acetylgalactosaminidase (endo-GalNAcdase) digestion. Preexisting PNA affinity in acinar cells from nonsecretors was also susceptible to endo-GalNAcdase treatment. Following the endo-GalNAcdase digestion, fucosidase or sialidase digestion recovered the PNA reactivity in acinar cells from nonsecretors. These results show that ABH determinants carried on O-glycosidically linked type 3 chain (D-galactose-(1-3)-N-acetyl-D-galactosamine1-serine or threonine) are secreted in pancreatic acinar cells and suggest that product coded by the secretor gene is required for the complete conversion of type 3 precursor chains into H determinants.