Function of the <Emphasis Type="Italic">rel</Emphasis> Gene in <Emphasis Type="Italic">Escherichia coli</Emphasis>

Sokawa et al. suggest that rel^- strains of Escherichia coli possess abnormal protein synthesizing machinery, which cannot carry out normal protein synthesis when the supply of amino-acids is limited.     

“Pleiotypic Response”

A hypothesis has been developed to relate stringent control in bacteria to a set of interactions involved in the regulation of growth of transformed and untransformed mammalian cells.     

Inhibition of DNA Synthesis but not of Poly-dAT Synthesis by the Arabinose Analogue of Cytidine <Emphasis Type="Italic">in vitro</Emphasis>

Kimball and Wilson¹ reported that the arabinose analogue of cytidine (ara-C) inhibited DNA polymerase in a crude extract prepared from Ehrlich ascites cells. Furth and Cohen² observed cytosine arabinoside triphosphate (ara-CTP) inhibited DNA polymerase in extracts from either calf thymus or bovine lymphosarcoma tissue, although these investigators³ had already found no effect of ara-CTP on DNA polymerase from Escherichia coli. The inhibition in both of these cases could be substantially reversed by dCTP; but incorporation of the arabinose nucleotide (ara-CMP) into DNA could not be unequivocally demonstrated. Graham and Whitmore⁴ reported the incorporation of ara-C into DNA in vivo and the inhibition of a DNA polymerase from L cells by ara-CTP. They found that ara-CMP was initially incorporated into small DNA strands but subsequently appeared in long strands. Momparler⁵ has presented evidence that, in vitro, ara-C incorporation was limited to the 3′-hydroxyl end of DNA chains. Such incorporation might be expected to block further chain elongation but this expectation was not supported by the evidence presented by Graham and Whitmore.     

Endopeptidase Activity of Phage λ-Endolysin

JACOB and Fuerst^1,2 demonstrated the presence of a bacteriolytic enzyme (λ-endolysin) in the induced cultures of lysogenic Escherichia coli K12 (λ). The enzyme was later identified as the product of gene R; of phage λ³ which is involved in bacterial lysis at the end of a latent period. The enzyme is apt to form spheroplast-like structures in E. coli² and one would therefore expect its substrate to be murein.     

Induced Bivalent Interlocking and the Course of Meiotic Chromosome Synapsis

WHEN chromosomes pair at meiosis the bivalents so formed do not normally interlock. Heat-treatments can, however, induce bivalent interlocking in the locust Locusta migratoria. Only the longest bivalents interlock and usually only two are found per cell; two “rod” bivalents, with single chiasmata, two “ring” bivalents, each with two or three chiasmata, or one “rod” and one “ring” bivalent (Fig. 1a, b and c). The nature of this interlocking and the metaphase orientational and congressional properties of interlocked bivalents are analysed in detail elsewhere¹.     

Potential bile acid metabolites. 14. Hyocholic and muricholic acid stereoisomers

The complete set of the eight theoretically possible stereoisomeric 3,6,7-trihydroxy-5 beta-cholanic acids, four of which are new, related to hyocholic and muricholic acids were prepared from chenodeoxycholic acid. The principal reactions used were 1) cis-dihydroxylation of delta 6-compounds with osmium tetroxide/N-methylmorpholine N-oxide; 2) trans-dihydroxylation of 6 alpha, 7 alpha-epoxy compounds with boron trifluoride etherate in N,N-dimethyl-formamide; 3) inversion of equatorial 3 alpha-hydroxylated compounds to the corresponding 3 beta-epimers with diethyl azodicarboxylate/triphenylphosphine/formic acid; and 4) stereoselective reduction of 7-keto derivatives with zinc borohydride (or sodium borohydride) and by metallic potassium/tert-amyl alcohol.     

Bent DNA is needed for recombinational enhancer activity in the site-specific recombination system Cin of bacteriophage P1. The role of FIS protein

A series of recombinational enhancer mutants was constructed by manipulating the ClaI site between the two FIS binding sites of the Hin enhancer. These mutants include insertions from two to 12 base-pairs and two deletions of one or two base-pairs. Recombinational enhancer activity was found only with four mutants carrying either a four base-pair substitution, ten base-pair insertions or a one base-pair deletion, respectively; two other ten base-pair insertion mutants, however, were inactive, although FIS protein binding was unaffected. So, besides binding of FIS protein to its specific sites within the enhancer sequence and the correct helical positioning of these sites on the DNA, another criterion for enhancer activity must be fulfilled. DNA bending assays identify this requirement as a change of the enhancer DNA conformation, which FIS protein is able to induce and to stabilize. This conformational change of the DNA can be blocked by mutations in the central segment between the two FIS binding sites of the Hin enhancer. This sequence has special functions for the recombinational enhancer activity.     

A rice (Oryza sativa L.) mutant having a low content of glutelin and a high content of prolamine

Among the mutant lines of rice that have been selected for morphological characters, one line, NM67, was found to have a low content of glutelin and a higher content of prolamine in its seed protein than other Japanese cultivars. This mutant is a semi-dwarf and partially sterile line, and its leaves turn yellow before heading. Genetic analysis after backcross to the original cultivar, Nihonmasari, revealed the following: (1) the character of low glutelin content was always accompanied by the character of high prolamine content; (2) the low glutelin (and high prolamine) character seemed to be manifested by a single dominant gene; and (3) semi-dwarfness, low fertility and early yellowing leaf of the mutant, which might also be pleiotropy, were controlled by a single recessive gene independent of the gene for protein content. The protein character of NM67 was genetically separated from semi-dwarfness and low fertility, and a new line having low glutelin content and high prolamine content with normal morphological characters comparable to those of the original cultivar was obtained from the progenies of the cross. The possible use of this line as a low protein rice cultivar is discussed.