Scopolin, a Biochemical Marker for Resistance to Thielaviopsis basicola in Callus and Crown-Gall Tissue Cultures of Tobacco

Scopolin concentration increased in tissue cultures where Thielaviopsis basicola growth ceased (primary and established callus cultures of the resistant tobacco cultivar Ky 170) while it decreased in tissue cultures where fungal growth persisted (primary and established callus cultures of the susceptible tobacco cultivar Ky 151 and crown-gall cultures of Ky 170 and Ky 151). The concentration of chlorogenic acid, scopoletin, and two other unknown soluble phenols varied after inoculation and no, correlation with tissue culture resistance could be established. Incorporation of Agrobacterium tumefaciens T-DNA in the genome of both cultivars induced a drastic reduction of scopolin in inoculated tissue cultures. T-DNA incorporation had less, influence on uninoculated tissues. Scopolin at concentrations found in tissue cultures was not toxic to the fungus.     

Resistance of Tobacco to Thielaviopsis basicola under Tissue Culture Conditions and Increased Susceptibility after Transformation with Agrobacterium tumefaciens T-DNA

Tobacco callus cultures from a Thielaviopsis basicola (Berk. et Br.) Ferraris resistant cultivar were less severely colonized than callus cultures from susceptible cultivars by the pathogen at all concentrations of kinetin and α-indoleacetic acid tested. However, at concentrations where these substances influenced the morphology of the callus cultures they also influenced the degree of colonization by the fungus. Incorporation of T-DNA of Agrobacterium tumefaciens induced susceptibility in tissue culture of the resistant cultivar but did not significantly modify the reaction of the susceptible cultivar tested.     

Phospholamban of cardiac sarcoplasmic reticulum consists of two functionally distinct proteolipids

Phosphorylation of phospholamban by either a cAMP-dependent or a calmodulin-dependent kinase stimulates the Ca²⁺ transporting activity of cardiac sarcoplasmic reticulum membranes. It has now been found that phospholamban consists of 2 distinct proteins; one is the specific substrate for the cAMP-dependent phosphorylation, and the other for the calmodulin-dependent kinase. In spite of functional diversity, the 2 polypeptides share a number of properties. Among them, the proteolipid character, M_r, resistance to trypsinization, and subunit composition.     

Genetic control of the immune response in mice: V. Minor genes involved in the response to H-Y and Ea-1 antigens

Murine responses to both the male specific histocompatibility antigen H-Y and the erythrocyte alloantigen Ea-1 are regulated by genetic factors. In each case a single major gene that controls the immune response has been identified, but additional modifying factors can be demonstrated if appropriate strain combinations are studied. A single gene controlling the response to Ea-1 antigens, which segregates when strains YBR and B10.D2 are crossed, has been shown not to be an allele of theIr-2 locus. A new phenomenon has also been observed in the control of anti-Ea-1 antibody production in that the mating of two responding strains, YBR and HTG, produces an F₁ generation of complete nonresponders. By linkage tests it was shown that the responding strain HTG possesses the nonresponder allele at theIr- 2 locus, so there appear to be recessive genes in the background which are able to overcome the suppressive influence of this allele.     

An endochitinase gene expressed at high levels in the stylar transmitting tissue of tomatoes

A gene (pMON9617; Chi2;1) identified by screening a tomato pistil cDNA library has been found to encode a protein similar in sequence to class II chitinases. Using a baculovirus expression system we show that the Chi2;1 protein is an active endochitinase. The Chi2;1 protein is most similar in sequence to a previously described stylar chitinase (SK2) isolated from potato. Both proteins lack the diagnostic N-terminal cysteine-rich regions and the C-terminal vacuolar targeting signals of class I chitinases and appear to define a novel type of class II endochitinases associated with flowers. Chi2;1 is expressed predominantly in floral organs and its expression within these organs is temporally regulated. The highest level of expression is found in the transmitting tissue of the style where Chi2;1 mRNA begins to accumulate just prior to anthesis. In vegetative tissue, low levels of Chi2;1 mRNA were detected, and these levels did not increase in response to wounding or treatment with ethephon. mRNA from Chi2;1 orthologs was not detected in most other angiosperms tested, even including some members of the Solanaceae, and it is therefore unlikely that Chi2;1 is essential for stylar function. A fragment containing 1.4 kilobase pairs of 5-flanking DNA from the Chi2;1 gene was shown to drive high-level expression of an attached reporter gene in the styles of transgenic tomatoes. This fragment has utility for engineering expression of other coding regions in styles.