Search

Abstract: The effect of 6-benzylaminopurine (6-BA) alone or in combination with naphthaleneacetic acid or indoleacetic acid on the morphogenetic response of cotyledon explants of Citrullus colocynthis (L.) Schrad. was tested. The best results were obtained with a medium containing 25 µm 6-BA, which yielded organogenic calli at a frequency of 81.8%. When these organogenic calli were transferred to elongation medium (basal medium supplemented with 0.5 µm 6-BA), 80% produced well-developed shoots. These shoots rooted normally when cultured on rooting medium containing indolebutyric acid at 2.5 or 5.0 µm. Plants grew to maturity under greenhouse conditions and gave normal fruits. Cotyledon explants were transformed by cocultivation with Agrobacterium tumefaciens LBA4404 carrying the binary vector pBI121 which bears the reporter gene β-glucuronidase (gus) and the marker gene neomycin phosphotransferase (nptII). Transformants were selected for growth capacity on medium with 100 mgl–1 of kanamycin. On the basis of β-glucuronidase expression, the transformation frequency was 14.2%. Molecular characterization by polymerase chain reaction confirmed the presence of the two genes transferred (gus, nptII) in the transgenic plants. Sexual transmission of both genes was also confirmed by studying their expression in progenies from several transgenic plants.

Abstract: An annular neutron source offers the possibility of positioning a large sample, surrounded by a paraffin thermalizing shield, inside the central tube. The optimal shield/sample ratio is determined experimentally. The absolute value of the thermal neutron flux is determined by irradiating NaHCO3 and evaluating the induced24Na-activity by the sumpeak method. Average fluxes over the seven irradiation capsules are presented. Some current applications are discussed.

Using the optical optical double resonance (O.O.D.R.) technique, Na2 molecules in a supersonic beam are ionized in well defined v J levels of the Na2+X2∑u+ ground state. These ions are then laser photodissociated as a function of the previously prepared vibrational level. As a result, we determine the potential curve of the first Na2+2Πu state. Dipole moment transition and photodissociation cross-sections are also calculated.