Physiological Growth Attributes of Saccharum Clones and their Progenies

Characters obtained by growth analysis techniques were studiedin seven sugar-cane clones and their seedling progenies froma ratton crop 139 days after virgin harvest. Significant differences in progeny means for R_wand E_Awere mainlyaccounted for by differences in L. Four select clones had amean R_w and mean E_A which, when adjusted to allow for theirsuperior L, were significantly greater than average (P< 0.05).This illustrated that for selection to be effective from theprogenies, segregants with improved L and better leaf-area dependencemust be isolated. The estimates obtained of both L and E_A wereeffective in predicting final weight of cane. Variance componentsindicated especially large ‘male X female’ interactionin progeny means. Some evidence was obtained to suggest thatleaf-area ration is a character which could be used in selectingsmall plots for weight.     

A Modified Method for Extraction and Identification of Abscisic Acid and Gibberellin-like Substances from the Olive (Olea europaea)

A procedure for extracting and identifying plant hormones, particularly abscisic acid (ABA) and the gibberellins (GA) was developed through modification of methods described in the literature. The procedure is particularly useful for studying more than one hormone simultaneously in a given sample, and when the supply of plant material is limited. The procedure was used to isolate ABA and GA-like substances from olive tissue (i.e., leaves, buds and inflorescences). Gibberellin-like substances were identified by their action on α-amylase release from embryoless barley half-seeds. Characterization of an acidic inhibitor extracted from olive inflorescences by thin-layer chromatography, fluorescence under ultraviolet light, gas chromatography, and physiological effects on wheat coleoptile sections indicate that this inhibitor, or at least a component of it, is very similar if not identical with at least one isomeric form of synthetic abscisic acid.     

In vitro Transcription of Kinetoplast and Nuclear DNA in Kinetoplastida*†

SYNOPSIS. DNA-dependent RNA polymerases have been solubilized from homogenates of Crithidia fasciculata using gentle extraction procedures. RNA polymerase I and II are separated on DEAE cellulose at 0.07M (NH₄)₂SO₄ and 0.13M (NH₄)₂SO₄ respectively. RNA polymerase II is inhibited 80% by α-amanitin (25 μg/ml). Both RNA polymerases require DNA as a template, ribonucleoside triphosphates and Mn²⁺. The synthesis of RNA as a product is inhibited by DNase. RNase, pronase and actinomycin D. Purified kinetoplast and nuclear DNA can serve as templates for the RNA polymerases. Denatured DNA templates are preferred. The synthesis of RNA continues for at least an hour and is inhibited by trypanocidal drugs including suramin. antrycide, acriflavine, ethidium bromide and berenil. Complementary RNA synthesized in vitro from C. fasciculata kinetoplast DNA hybridizes with C. fasciculata kinetoplast DNA but not with C. fasciculata nuclear DNA or Blastocrithidia culicis kinetoplast DNA, Escherichia coli, T4 or calf thymus DNAs. The complementary RNA synthesized in vitro from C.fasciculata kinetoplast DNA sediments at 4–5S.     

Activities of Carboxylation Enzymes in Freshwater Macrophytes

Fifteen species of freshwater macrophytes, mainly from cool,temperate waters, were assayed for ribulose bisphosphate carboxylase-oxygenase(RuBPCase) and phosphoenolpyruvate carboxylase (PEPCase) activities.In extracts from all the species RuBPCase was the most activecarboxylation enzyme, and the RuBPCase/PEPCase ratio was atleast 2·0, even for the submersed species Isoetes lacustrisL. and Littorella unifiora (L.) Aschers. which have been reportedto show Crassulacean Acid Metabolism (CAM) activity. The PEPCaseactivity in I.lacustris was lower than that found in some non-CAM-likespecies. In this respect, I.lacustris and L unifiora differfrom most terrestrial CAM plants. However, these two species,along with Potamogeton praelongus Wulf. and Juncus bulbosusvar.fluitans L., had the lowest RuBPCASE/PEPCase ratios, lowerthan found in terrestrial C₃ species; suggesting that the potentialfor substantial photosynthetic metabolism of C₄ acids existsin some temperate, submersed plants. In the three amphibiousspecies (Potamogeton polygonifolius Pourr., Mentha aquaticaL., and Hippuris vulgaris L.) examined, the aerial leaves exhibitedhigher RuBPCase activities than the submersed leaves. Key words: Ribulose bisphosphate carboxylase-oxygenase, phosphoenolpruvate carboxylase, freshwater macrophytes