Segregation of elongation potential inEscherichia coli mediated by thewee genetic system

Under normal conditions, the two cells within a pair ofEscherichia coli siblings elongate at a similar rate. Genetic impairment of thewee genetic system leads to significant variations in the rate of elongation of each cell within a given pair of siblings. This result is in accordance with previous reports that showed the need of active cell division for expression of the Wee phenotype. The genetic location of one element of the system,weeA, has been determined to be at min 67 of theE. coli map; this does not coincide with the previously reported genetic location. The inability to reproduce the Wee phenotype in a wild-type background by transduction ofweeA suggests that more genetic elements should participate in the segregation of elongation zones at cell division.     

A genetic study of tolerance and resistance to colicin A inCitrobacter freundii

Colicin A-insensitive mutants ofCitrobacter freundii were isolated and grouped into six phenotypic classes characterized by sensitivity, insensitivity or partial insensitivity to the bacteriocins S6, DF 13 and colicin A, and sensitivity or insensitivity to deoxycholate (DOC) and ampicillin. Mapping by the gradient-of-transmission method revealed the chromosomal regions in which the responsible genes are situated. Res-3 mapped nearpur betweenpur andthr; Tol-5 mapped betweenaro andilv and Tol-4 betweengal andpyr; Tol-1, Tol-2 and Tol-3 are situated close togal. All the mutations that mapped neargal rendered the bacteria more sensitive to DOC and ampicillin. Complementation analysis withE. coli plasmids showed that the three phenotypic groups that map neargal were complemented byE. coli plasmids and fall into three complementation groups. Two of these are equivalent with thetol A andtol B genes inE. coli.     

Corolla tube formation in the primulaceae and ericales

Corolla tube formation was investigated anatomically for 13 species of the Primulaceae and Ericales. In the Primulaceae, petal primordia appear after the stamen initiation. The lower portion of the corolla tube, the portion under the stamen insertion, is derived from the ring-like structure formed immediately after the stamen initiation. Petal bases extend laterally, and connect mutually on the ring-like structure. The upward growth at the connected regions results in the formation of a corolla tube, which develops into the upper portion of the corolla tube. In the Ericales, except forClethra, the corolla tube is formed by the mutual connection of petal bases. This tube elongates inRhododendron, Leucothoe andPieris. However, inPyrola, Ledum andTripetaleia, the elongation of this tube is meager, resulting in a dialypetalous condition in the mature state. Three petals ofTripetaleia may be derived from the partial connection of five petal primordia in a very early stage of the corolla development. From the data obtained in the studies on the corolla tube formation, three modes of the corolla tube formation are suggested; postgenital fusion, connection of petal bases, elongation of the ring-like common base.     

The effect of Sa and MiniSa plasmids on the induction of plant crown galls and hairy roots byAgrobacterium tumefaciens andAgrobacterium rhizogenes

The Inc-W group plasmid Sa or its derivative MiniSa were introduced into two strains ofAgrobacterium tumefaciens with Ti plasmids, one strain ofA. tumefaciens with the Ri plasmid and oneA. rhizogenes strain with the Ri plasmid. The effect was similar in allAgrobacterium strains. The pSa suppressed fully the virulence ofAgrobacterium strains (i.e. their ability to induce tumor growths - crown galls or hairj⁷ roots) inKalanchoe plants and carrot root slices. The MiniSa plasmid caused only a slight decrease of the frequency and size of tumor growths induced. The mechanism of suppression of virulence by the Sa plasmid inAgrobacterium tumefaciens andAgrobacterium rhizogenes seems to be similar.     

Restriction endonucleases R.EcoKI and R.EcoR124I are probably located in different environments within the bacterial cell

We describe the phenomenon of a transient state of R124I restriction deficiency after long-term storage of theE. coli[pCP1005] strain at 4°C, or after growth of the culture in synthetic M9 medium with the nonmutagenic solvent dimethyl sulfoxide. The unusual high reversion from the R⁺ ₁₂₄ to the R^? ₁₂₄ phenotype was observed only inE. coli strain transformed with the high-copy number plasmid pCP1005 carryingECoR124IhsdR, M and S genes cloned, but not with strains carrying the natural conjugative plasmid R124. The effect of both treatments on the expression ofEcoR124I phenotype in relation to the possible location of R.EcoR124I restriction endonuclease inE. coli is discussed.     

Expression inE. coli of the cloned cDNA for the major antigen of foot and mouth disease virus Asia 1 63/72

Double stranded cDNA for the foot and mouth disease virus was prepared, restricted withBamH 1 or ligated to linkers withBamH 1 sticky ends and cloned inBamH 1 site in the expression vector, pU R222. The cDNA was also cloned at thePst 1 site in the same vector by the dC/dG tailing method. They were transferred intoE. coli to give colourless colonies in the presence of the dye, X-gal. Many of them showed positive signal on hybridization with³²P-labelled viral RNA. The middleBamH1 fragment of the cDNA is known to carry the gene for the major antigen and some non-structural proteins. The clones carrying the recombinant DNA produced proteins which cross-reacted with the antibodies generated against the structural proteins of the virus in an enzyme linked immunosorbent assay, indicating that the cDNA of the major antigen is expressed in the cloned cell.     

Opposing effects of strychnine and brucine on the germination and growth of lettuce seeds

Strychnine and brucine, two related alkaloids that occur in plants belonging to theStrychnos species, were shown to have opposing effects on the elongation of the radicle of lettuce seeds. Strychnine was found to be inhibitory, whereas brucine was found to be stimulating to radicle elongation. Alkaloids, generally, are more commonly known for their inhibitory effects on plant growth rather than on their stimulating effects.     

The biosynthesis of the gibberellin precursorent-kaurene in cell-free extracts and the endogenous gibberellins of Japanese morning glory in relation to seed development

The endogenous levels of gibberellins (GAs) determined by a combined HPLC-bioassay procedure and the formation ofent-kaurene, an immediate GA precursor, in cell-free extracts were studied in relation to seed development inPharbitis nil Choisy cv. Violet. Three biologically active GA fractions were obtained, tentatively identified as GA₃, GA₅/ GA₂₀, and a GA fraction, possibly GA₁₉ and/or GA₄₄, which all increased in activity during early seed development and subsequently declined during maturation of the seeds. The total endogenous GA level reached its maximum at 19 days after anthesis, just before the seeds had attained their maximum fresh weight at about 23 days after anthesis. Similarly, theent-kaurene synthesizing capacity showed a rapid increase during the period of rapid growth of the seeds, followed by a decline during maturation. A direct relationship between the endogenous GA levels and theent-kaurene synthesizing capacity of a particular tissue was indicated.     

Amino acid sequence of myoglobin from the molluscBursatella leachii

The complete amino acid sequence of myoglobin from the triturative stomach of gastropodic molluscBursatella leachii has been determined. It is composed of 146 amino acid residues, is acetylated at the N-terminus, and contains a single histidine residue at position 95 which corresponds to the heme-binding proximal histidine. The E7 distal histidine, which is conserved widely in myoglobins and hemoglobins, is replaced by valine inBursatella myoglobin. The amino acid sequence ofBursatella myoglobin shows strong homology (73–84%) with those ofAplysia andDolabella myoglobins.     

Anatomy and systematics of Dendroseris (sensu lato)

Anatomical study of the genusDendroseris (Compositae: Cichorieae), endemic to the Juan Fernandez Islands, was undertaken to determine if segregate genera were valid. Other questions include the significance of pith bundles and of receptacular bristles, and whether the ancestors of these peculiar rosette trees and shrubs were woody or herbaceous. Anatomical evidence, when added to that from gross morphology, suggests that the segregation as distinct genera ofRea, Phoenicoseris, andHesperoseris is probably not justified, and that they are better treated as subgenera ofDendroseris. Differences in pollen morphology, floral trichomes, achene and leaf anatomy provide good species characteristics. These all appear, respectively, as variations on a basic plan, andDendroseris can be envisaged as derived from a common stock in the Juan Fernandez Islands. The genus is not particularly primitive within the family or tribe. The presence of additional bundles in the flowers ofD. litoralis may be interpreted as related to gigantism. The separate corolla lobes inD. gigantea probably do not represent a vestige of an actinomorphic condition. Pith bundles inDendroseris may have been present in ancestors; in any case, they seem likely to have increased in prominence with increase in stem diameter. Available evidence seems to favor the interpretation of growth forms inDendroseris as derived from an herbaceous ancestry.     

Stability of the hybrid plasmid pIM138 and its curing by some eliminating agents

Hybrid plasmid pIM138 was constructed by insertion of a chromosomal fragment with the threonme operon fromEscherichia coli into the pBR322 vector. Molar mass of pIM138 was 2.8 Mg/mol. Heteroduplexes between pBR322 vector and pIM138 hybrid DNA molecules were prepared. The hybrid plasmid shows a high stability against the curing effect of rifampicin and clorobiocm inE. coli SK1590thr host.     

The role of non-specific serum opsonins in thein vitro interaction (adherence) between peritoneal macrophages of newborn precolostral piglets and rough strain ofEscherichia coli

The role of non-antibody, natural opsonins in sera of newborn, precolostral piglets for the early phase of phagocytosis (adhesion) of roughEscherichia coli to peritoneal macrophages of these animals, was studied. Suspensions of macrophages, incubated together with bacteria in the presence or absence of piglet serum opsonins, were submitted to differential centrifugation to enable the separation of macrophage-associated bacteria (i.e. opsonized) from unopsonized, free bacteria in the supernatant. It was found that native piglet sera having no detectable antibody activity toEscherichia coli, do possess significant opsonic activity,i.e. they enhanced thein vitro adherence of roughEscherichia coli to macrophages. Furthermore, this activity could be removed by procedures or substances known to inactivate the complement by different mechanisms: heating for 30 min at 56°C, addition of EDTA, absorption of sera by zymosan, addition of complement inhibitors phosphomannan and carrageenin. These results are interpreted as further evidence for the presence of complement-dependent serum opsonins to roughEscherichia coli in sera of newborn precolostral piglets.