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Cotyledon segments derived from zygote embryos of mango (Mangifera indica L. cv. Zihua) were cultured on agar medium for 28 days. Depending on different pre-treatments with plant growth regulators, two distinct patterns of adventitious roots were observed. A first pattern of adventitious roots was seen at the proximal cut surface, whereas no roots were formed on the opposite, distal cut surface. The rooting ability depended on the segment length and was significantly promoted by pre-treatment of embryos with indol-3-acetic acid (IAA) or indole-3-butyric acid (IBA) for 1 h. A pre-treatment with the auxin transport inhibitor 2,3,5-triiodobenzoic acid (TIBA) completely inhibited adventitious root formation on proximal cut surfaces. A second pattern of roots was observed on abaxial surfaces of cotyledon segments when embryos were pre-treated with 2,700 μM 1-naphthalenacetic acid (NAA) for 1 h. Histological observations indicated that both patterns of adventitious roots originated from parenchymal cells, but developmental directions of the root primordia were different. A polar auxin transport assay was used to demonstrate transport of [3H] indole-3-acetic acid (IAA) in cotyledon segments from the distal to the proximal cut surface. In conclusion, we suggest that polar auxin transport plays a role in adventitious root formation at the proximal cut surface, whereas NAA levels (influx by diffusion; carrier mediated efflux) seem to control development of adventitious roots on the abaxial surface of cotyledon segments.

Three new Ru(II) complexes, [Ru(dmb)2(ipad)](ClO4)2 (dmb = 4,4′-dimethyl-2,2′-bipyridine, ipad = 2-(anthracene-9,10-dione-2-yl) imidazo[4,5-f][1,10]phenanthroline, 1), [Ru(dmp)2(ipad)](ClO4)2 (dmp = 2,9-dimethyl-1,10-phenanthroline, 2), and [Ru(dip)2(ipad)](ClO4)2 (dip = 4,7-diphenyl-1,10-phenanthroline, 3), have been synthesized and characterized. The three Ru(II) complexes intercalate with the base pairs of DNA. The in vitro antiproliferative activities and apoptosis-inducing characteristics of these complexes were investigated. The complexes exhibited cytotoxicity against various human cancer cell lines. BEL-7402 cells displayed the highest sensitivity to 1, accounted for by the greatest cellular uptake. Complex 1 was shown to accumulate preferentially in the nuclei of BEL-7402 cells and cause DNA damage and induce apoptosis, which involved cell cycle arrest and reactive oxygen species generation.

The transfer behaviour of alkali metal ions across the water-nitrobenzene interface facilitated by nonionic surfactants poly(oxyethylene)dodecyl ethers (C 12 E x ) were investigated by means of cyclic voltammetry. The results show a linear dependence of the reversible half-wave potential Δ w n φ 1/2 on the logarithm of the concentration of alkali metal ions in the aqueous phase. Therefrom, the apparent free energy change of ion transfer facilitated by C 12 E x , ‡ w n G 0 tr , was determined. The results indicate that the ion transfer facilitated by C 12 E x is attributable to the formation of a hydrophobic complex of alkali metal ion with C 12 E x and its ion pairs with the counter anion, and the rate of transfer is controlled by the diffusion of C 12 E x from the bulk nitrobenzene phase to the interface.

The thermodynamic and kinetic behaviours of alkali metal ion transfer facilitated by some crown ethers (18-crown-6, dibenzo-18-crown-6, dibenzo-24-crown-8) from water to nitrobenzene were studied by means of cyclic voltammetry and impedance measurement. The results indicate that each crown ether forms complexes with the respective alkali metal cations, of which stability constants are dependent on the sort of crown ethers and alkali metal cations. Moreover, the potential dependence of the rate constant of the facilitated ion transfer is sensitive to the stability constant in the nitrobenzene phase.

In this paper, we described the direct somatic embryogenesis from both immature cotyledon cuts and nucelli in the same mango cultivar (Mangifera indica L. var Zihua), studied the effect of growth conditions of embryogenic cultures (EMs) on cryopreservation and compared the cryopreservation response of EMs induced from these two different explants. Histological studies demonstrated that EMs derived from nucelli could be induced directly from epidermal cells of both sides of nucelli, whereas EMs derived from cotyledon cuts were induced only from epidermal cells of the adaxial side of the cotyledons. EMs from either nucelli or cotyledon cuts could be maintained in liquid medium or on solid medium and cryopreserved using a vitrification procedure. Success of cryopreservation of EMs depended on the dehydration treatment and the defined growth conditions during culture but not on their origins. When EMs were sampled during their exponential growth phase in liquid medium and dehydrated with PVS(3) solution for 5 min, survival of the EMs induced from cotyledon cuts and nucelli reached 77.7 and 80%, respectively, after cryopreservation in liquid nitrogen for 24 h. Furthermore, when dehydrated with PVS(3) solution for 30 min, all EMs induced from cotyledon cuts and 96.7% of EMs induced from nucelli could survive after cryopreservation. Cryopreservation did not affect the plant regeneration potential of EMs through somatic embryogenesis. The protocols of somatic embryogenesis and cryopreservation of mango EMs established in this study may offer potential ways to improve mango germplasm conservation and genetic improvement.