Differences in the Activation State of Ribulose-1,5-bisphosphate Carboxylase/Oxygenase in Barley,Pea, and Wheat at Two Altitudes

Activation state of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCO) is an important parameter determining the rate of net photosynthesis (P _N) in situ for which no information is available with reference to altitude. We analyzed activation state along with P _N in three plant species and their cultivars grown at low (LA, 1 300 m) and high (HA, 4 200 m) altitudes. No significant change in P _N and the initial activity of RuBPCO was obtained with reference to altitude. However, activation state of RuBPCO was reduced significantly in the HA plants as compared to the LA ones. Hence low partial pressure of CO₂ prevailing at HA might be responsible for the lower activation state of RuBPCO.     

A bacterial cytochrome c heme lyase. CcmF forms a complex with the heme chaperone CcmE and CcmH but not with apocytochrome c.

Biogenesis of c-type cytochromes in Escherichia coli involves a number of membrane proteins (CcmA-H), which are required for the transfer of heme to the periplasmically located apocytochrome c. The pathway includes (i) covalent, transient binding of heme to the periplasmic domain of the heme chaperone CcmE; (ii) the subsequent release of heme; and (iii) transfer and covalent attachment of heme to apocytochrome c. Here, we report that CcmF is a key player in the late steps of cytochrome c maturation. We demonstrate that the conserved histidines His-173, His-261, His-303, and His-491 and the tryptophan-rich signature motif of the CcmF protein family are functionally required. Co-immunoprecipitation experiments revealed that CcmF interacts directly with the heme donor CcmE and with CcmH but not with apocytochrome c. We propose that CcmFH forms a bacterial heme lyase complex for the transfer of heme from CcmE to apocytochrome c.     

THE STOMATA OF NELUMBO NUCIFERA: FORMATION,DISTRIBUTION AND DEGENERATION

Contrary to earlier reports, well-organized but fewer stomata develop on the lower surface of the leaves of Nelumbo nucifera Willd. during aerial growth. The stomata, however, become obliterated by the readjustment of neighboring epidermal cells. During initial stages of degeneration the guard cells show irregularly thickened walls, disintegrated nuclei, and highly vacuolated cytoplasm. Such abnormal features finally lead to the disappearance of stomata from the lower surface of leaves. The ontogeny, structure and distribution of stomata on leaves, perianth lobes, stamens, receptacles and carpels are described. The stomata are haplocheilic in development and are anomocytic (ranunculaceous) at maturity. The concept of a meristemoid and the significance of this study in taxonomy and phylogeny are discussed.     

Clastogenic effect of the psychotropic drug thioridazine on human chromosomes in vivo

Summary This paper deals with some other population genetic aspects associated with the incidence of a type of primary congenital glaucoma that occurs very frequently in the Gypsy population of Slovakia. In addition to the decreased fertility of affected individuals of Gypsy origin being determined, the relative reproduction fitness and the selection coefficient against this disease were estimated. An increased number of kinship intermarriages in parents of the patients were recorded, namely in the Gypsy group (45.6%). The average inbreeding coefficient for the Gypsy group (F=0.0091) and the non-Gypsy group (F=0.0030) was calculated. Based on the high frequency of primary congenital glaucoma in a relatively small Gypsy subpopulation and on data about their origin, immigration, and settlements in the territory of Slovakia, the authors consider a special case of gene drift—the founder effect—to be the most plausible explanation of the given fact.     

Oscillatoria anguistissima: A Promising Cu2+ Biosorbent

Oscillatoria anguistissima rapidly adsorbs Cu²⁺ from aqueous solution. The adsorption of Cu²⁺ followed Freundlich Isotherm, and the amount of Cu²⁺ removed from solution increased with increasing Cu²⁺ concentration. The adsorption is pH dependent, and maximum Cu²⁺ removal occurs at pH 5. Of the various pretreatments, HCl treatment of the biomass increased the capacity for Cu²⁺ removal. Presence of Mg²⁺ and Ca²⁺ resulted in decline in the Cu²⁺ adsorption capacity of Oscillatoria cells. This species could also effectively remove Cu²⁺ from mine water containing 68.4 μg/ml of Cu²⁺ at pH 3.45. Received: 23 December 1996 / Accepted: 20 February 1997     

Excision of the maize transposable element Ac in periclinal chimeric leaves of 35S-Ac-rolC transgenic aspen-Populus

The transposable element Ac from maize, in combination with the phenotypic selectable marker rolC, was employed in transformation experiments of a hybrid aspen clone. A number of transgenic clones exhibited light-green sectors on green leaves. In vitro regeneration from leaves showing a high number of light-green spots resulted in R2 plants, which also showed light-green sectored leaves. However, only one out of 385 regenerated plants obtained showed green leaves. Both PCR and northern analysis indicated Ac excision and restoration of rolC expression. In Southern blot analysis of this green plant additional bands were observed as compared to the original R1 plant. The occurrence of these bands and a suggested Ac excision in the non-green L1-epidermal layer leading to periclinal chimerism of this plant is discussed.     

Production of hairy roots in Aconitum heterophyllum wall. using Agrobacterium rhizogenes

Summary A method for the production of hairy roots of Aconitum heterophyllum wall. is reported for the first time. Embryogenic callus cultures were successfully transformed using Agrobacterium rhizogenes strains viz. LBA 9402, LBA 9360, and A4 for the induction of hairy roots. The transgenic nature of hairy roots was confirmed by mannopine assay using paper electrophoresis. Best growth of transformed roots was obtained on 1/4 MS (Murashige and Skoog, 1962) medium with 3% sucrose. Total alkaloid (aconites) content of transformed roots was 2.96%, which was 3.75 times higher compared to 0.79% in the nontransformed (control) roots. Thin layer chromatography (TLC) analysis of the components of aconites in the transformed roots revealed the presence of heteratisine, atisine, and hetidine.