Effects of Growth Regulators and Glutamine on In Vitro Development of Zygotic Embryos of Taro (Colocasia esculenta var. antiquorum)

Zygotic embryos of taro, Colocasia esculenta var. antiquorumcultured on Linsmaier-Skoog (LS) medium without the additionof hormones develop into mature plants only in the presenceof endosperm tissue. Growth is usually evident within the firstweek of culture when embryos swell and become green. Embryosexcised from endosperm and cultured on LS containing 0-01 mg1^–1 naphthaleneacetic acid (NAA), and 0–01 mg 1^–16-dimethylaminopurine (6-DMAP) grow at a rate comparable withcontrols for the first week of culture. During the second week,growth rates are higher than controls primarily because embryosform elongated hypocotyl regions which often produce swollentissues and/or callus. In the presence of 200 mg 1^–1 glutamineand a range of concentrations of 6-dimethylaminopurine, benzyladenine,or NAA, elongation of the hypocotyl axis is inhibited, and acompact callus may develop. Embryos grown on LS containing 200mg 1^–1 glutamine and 2.0 mg 1^–1 2, 4, 5-trichlorophenoxyaceticacid form friable callus which was used to generate short-livedsuspension cultures. Growth Regulators, Glutamine, tygotic embryos, Colocasia esculenta, endosperm     

NAD- and NADP-Linked Glyceraldehyde-3-Phosphate Dehydrogenases in Light- and Dark-Germinated Seeds of Scots Pine (Pinus silvestris)

By means of arsenate in optical tests the occurrence of both NAD- and NADP-linked glyceraldehyde-3-phosphate dehydrogenase activity has been found in embryo and endosperm tissues from Scots pine seeds. By exclusion of arsenate also evidences for the activity of a non-phosphorylating NADP-linked form have been demonstrated. The results are sustained by inhibition experiments. The enzyme activities have been followed principally during the first 24 hours of the germination process and in relation to the germination-controlling light factor. Homogenates from complete seeds and partly also from separated embryo and endosperm tissues have been studied. The predominant activity in both of the tissues was linked to the NAD-form, expressed either on seed (part) or protein basis. No indications for a light-regulation of anyone of these enzymes have been found contrary to findings from other plant materials.     

Reversible Structural Changes Associated With Callus Formation and Plantlet Development from Aseptically Cultured Shoots of Taro (Colocasia esculenta var antiquorum)

Taro callus maintained on Knop's medium with 2, 0·2 or0·02 mg l^–1 2,4,5-trichiorophenoxyacetic acid (2,4,5-T)or Linsmaier-Skoog (LS) containing 1 mgl^–1 of the cytokininadenine-N-benzyl-9-tetrahydro-2H- pyran-2-yl (SD8339) or 6 dimethylaininopurineand 0·1 mgl^–1 -naphthaleneacetic acid underwenta transition to a stable organized growth form which is referredto as a calloid. On transfer to LS medium th 0·2 mgl^–12,4,5-T in the absence of cytokinin the calloid reverts backto callus. Colocasia esculenta(L.)Schott, taro, callus, calloid, in vitro selection, histology, micropropagation, tissue culture, cytokinin     

Metabolism of Arginine and Ornithine in Suspension-Cultured Cells and Aseptic Roots of Intact Plants of Atropa belladonna

Suspension-cultured cells and aseptically cultured roots ofintact plants of Atropa belladonna L. removed tropane alkaloidprecursors arginine (Arg) and ornithine (Orn) at nearly an equalrate from the feeding medium. A great part of Arg- and Orn-derived¹⁴C-label was found in ethanol-insoluble compounds, mostly inproteins already after 2 h feeding. Ethanol-soluble label inthe roots was found mainly in amino acids (e.g. glutamine, Gln)after 2 h feeding, and after 20 h also in some intermediatesof the urea cycle (e.g. argininosuccinate). In suspension cultures, subculturing of the initiation callusdecreased both the uptake of the basic amino acids tested andtheir binding on to the apoplastic space. After 20 h feedingwith Arg more label was found in organic acids in stationaryphase suspension cultures with repressed alkaloid synthesisthan in roots producing alkaloids. The growth phase and passagenumber also affected into which amino acids the label was incorporated.When the initiation callus was young (the 3rd passage), theintermediates of the urea cycle were actively labelled, butwhen the initiation callus was older (the 8th passage) and thesuspension formed roots, especially Gln was labelled. Only tracesof -N-methylornithine were detected in feeding experiments withOrn and Arg. Considerable arginase activity with a high pH optimumwas observed in cell suspensions and roots of A. belladonna. Key words: Atropa, arginine, ornithine, roots, suspension culture     

Species Specific Enzymes in Some Snail Species (Mollusca, Gastropoda) from Fresh and Brackish Water in Sweden

Horizontal starch gel electrophoresis was employed to reveal possible species specific patterns of esterases and peroxidases in four species of Lymnaea, Myxas glutinosa, Bithynia tentaculata, Theodoxus fluviatilis and the genus Hydrobia. From four of the species specimens from both fresh and brackish water were used. Esterase patterns were species specific in the anodic portion of the zymograms in all species. The remainder of the patterns displayed marked individual variation, the nature of which was not investigated. The peroxidases also revealed clearly species specific patterns. The amount of variation exhibited in fresh and brackish water populations of L. peregra and T. fluviatilis , the most thoroughly investigated species, was found to be roughly of the same magnitude, indicating a similar amount of intra-specific variation in fresh and brackish water. In the four Lymnaea species it appears from the peroxidase patterns that alternative alleles from an ancestral polymorphic locus have become established in different species. The esterase patterns of L. peregra and L. auricularia revealed distinct differences between the two taxa, which is also supported by the appearance of the spermathecal duct, whereas shell morphology and immunological investigations fail to show inter-taxon differences.