Changes in Eucalyptus camaldulensis essential oil composition as response to drought preconditioning

Abstract

Water deficit, a common constraint in forestry, is the main cause of plant stress during plantation. The survival and growth of seedlings is also compromised by herbivory during establishment. The potential of nursery preconditioning to enhance survival chances of future trees by reducing palatability or attracting beneficial insects as a result of changes in chemical defences may be an answer to overcome this situation. Changes in essential oil production and composition were evaluated by GC and GC-MS in Eucalytus camaldulensis seedlings submitted to drought during four weeks at the last stage of nursery period (20 weeks). Significant changes in essential oil relative composition were found. Seedlings (young leaves) submitted to drought developed a terpenoid blend, which has been previously associated to mature leaves and related to their higher resistance towards herbivory. Total amount of non-oxygenated terpenes decreased by 44%, whereas some oxygenated sesquiterpenes (globulol, epiglobulol and ledol) were doubled, and 1,8-cineole content was enhanced by 28.3%.     

River Red Gum (Eucalyptus camaldulensis Dehnh.) organic matter as a carbon source in the lower Darling River,Australia

The Darling River, in New South Wales, Australia, is a large semi-arid system with a highly variable flow regime, characterised by unpredictable events of flooding and drought. In large lowland rivers like the Darling, lateral (river-floodplain) interactions can greatly influence both physical and biological components of the system. The floodplain and riparian zone of the Darling River is dominated by River Red Gum (RRG), Eucalyptus camaldulensis. The large amount of organic matter they produce accumulates on the floodplain and on benches within the channel, and is subject to alternate periods of flooding and drying as a result of highly variable flows. This paper examines the effect of alternate periods of flooding and drying on the processing of E. camaldulensis organic matter. Results of the 6-month in situ field study, together with results from laboratory experiments comparing dissolved organic carbon (DOC) release from various RRG litter types, suggest that RRG leaves provide the most bio-available source of carbon to the system, while bark may be more important as a habitat for invertebrates and other fauna. Laboratory experiments exploring the effect of drying and re-flooding on litter breakdown and release of DOC suggested that the majority of DOC was released from RRG leaves in the first 24 h of inundation. Also, upon drying and re-flooding of the leaves, a smaller but significant release of DOC occurred. However, an alternative wet/dry cycle did not affect weight loss of the leaf litter. Results of the field and lab experiments suggest that RRG leaves represent an important source of carbon to the Darling River, with inputs being influenced by the highly variable flow regime.     

Phenolic compounds and antioxidants from Eucalyptus camaldulensis as affected by some extraction conditions,a preparative optimization for GC-MS analysis

Abstract

Four organic solvents along with water were applied for the conventional extraction of Eucalyptus camaldulensis (Myrtaceae), phenolic contents and antioxidant activities were investigated through variable protocols and correlation coefficients were considered, the phenolic composition was also characterized by Gas chromatography-mass spectrometry (GC-MS). Using solvents with dissimilar polarities affected the phenolic yields extracted from E. camaldulensis and their related antioxidant activities varied significantly among the four investigated plant organs. The leaf extract of acetone 70% contained the highest amount of phenolic compounds (46.56?mg/g dry weight); while the bud-water boiled extract maintained the maximum value of tannins (45.68?mg/g dry weight). Correlation coefficients indicated that phenolic compounds were mostly accountable for the phosphomolybednum antioxidant potentials (0.520), followed by tannins (0.460). Also, both the reducing power activities and hydrogen peroxide scavenging of E. camaldulensis extracts positively correlated with tannins, but at different significance degrees. However, the GC-MS analysis revealed that most of the detected phenolic constituents were more abundant in the plant seed. So, the existence of some other compounds such as organic acids, along with phenolics, may have increased the antioxidant potentials of leaf and bud. Undeniably, the optimization of extraction conditions could stimulate the antioxidant capabilities of the plant extracts of E. camaldulensis.     

Mass Propagation of Eucalyptus camaldulensis in a Scaled-up Vessel Under In Vitro Photoautotrophic Condition

A scaled-up culture vessel was designed for the large-scalephotoautotrophic micropropagation of chlorophyllous plants.The culture vessel (volume 20 l) contained a plug cell traywith 448 plantlets, and had a forced ventilation system to supplyCO₂-enriched air. A nutrient-reservoir was connected to theculture vessel from which nutrient solution was circulated tothe culture vessel every 24 h. Nodal leafy cuttings of Eucalyptuscamaldulensis L. were cultured photoautotrophically in thissystem without sugar in the nutrient medium, but with an enrichedCO₂concentration and a high photosynthetic photon flux. Thegrowth and the net photosynthetic rate of the in vitro grownplantlets and the survival percentage of the plantlets aftertransplanting to ex vitro conditions were compared with thoseof plantlets grown photoautotrophically under natural ventilationin conventional small culture vessels (Magenta-type vessels;volume 0.4 l). Fresh and dry masses and net photosynthetic ratewere significantly higher in plantlets grown in the scaled-upvessel compared to plantlets grown in the conventional smallvessels (control). The environmental conditions created in thisscaled-up vessel (with forced ventilation) also facilitatedacclimatizationin vitro . Importantly, after transplanting tothe ex vitro condition, plantlets grew well without any specializedexvitro acclimatization treatment. Copyright 2000 Annals of BotanyCompany CO₂enrichment, Eucalyptus camaldulensis L., ex vitro, forced ventilation, natural ventilation, photoautotrophic, scaled-up vessel, survival percentage     

Identification of a Ligand on the Wip1 Bacteriophage Highly Specific for a Receptor on Bacillus anthracis

Tectiviridae is a family of tailless bacteriophages with Gram-negative and Gram-positive hosts. The family model PRD1 and its close relatives all infect a broad range of enterobacteria by recognizing a plasmid-encoded conjugal transfer complex as a receptor. In contrast, tectiviruses with Gram-positive hosts are highly specific to only a few hosts within the same bacterial species. The cellular determinants that account for the observed specificity remain unknown. Here we present the genome sequence of Wip1, a tectivirus that infects the pathogen Bacillus anthracis. The Wip1 genome is related to other tectiviruses with Gram-positive hosts, notably, AP50, but displays some interesting differences in its genome organization. We identified Wip1 candidate genes for the viral spike complex, the structure located at the capsid vertices and involved in host receptor binding. Phage adsorption and inhibition tests were combined with immunofluorescence microscopy to show that the Wip1 gene product p23 is a receptor binding protein. His-p23 also formed a stable complex with p24, a Wip1 protein of unknown function, suggesting that the latter is involved with p23 in host cell recognition. The narrow host range of phage Wip1 and the identification of p23 as a receptor binding protein offer a new range of suitable tools for the rapid identification of B. anthracis.     

Maintenance of Inbreeding Depression in a Highly Self-Fertilizing Tree, Magnolia obovata Thunb

Inbreeding depression is a major selective force that maintains outcrossing in flowering plants. If the long life and large mature size of trees cause high inbreeding depression via mitotic mutations and half-sib competition, these characteristics may increase inbreeding depression sufficiently to maintain traits that facilitate outcrossing even with high primary selfing rates (proportion of selfed ovules). Here, I report the maintenance of inbreeding depression in a population of a tree (Magnolia obovata Thunb.) with primary selfing rates greater than 0.8 resulting from geitonogamy. The progenies exhibited inbreeding depression for germination, seedling survival, and seedling mass (δ = 0.29–0.38), but no significant difference between crossing type in seedling height. Cumulative inbreeding depression for early survival (from zygote to 2-year-old stage) estimated from these results and from prior data on embryonic survival was high (δ_e = 0.91). The fixation index at maturity based on six allozyme loci was low (F_is = 0.08), indicating that significant inbreeding depression for late survival results in a low level of inbreeding with respect to gene transmission to the next generation. From these results, I estimated that inbreeding depression for late and lifetime survival equaled 0.69 and 0.97, respectively. These results suggest that M. obovata trees maintain high inbreeding depression at both early and late life stages, resulting in a low level of inbreeding despite a high primary selfing rate. The high inbreeding depression can be explained by previous theories and is consistent with the predicted maintenance of inbreeding depression in highly self-fertilizing tree populations. The inbreeding load due to the high primary selfing rate represents a cost of this tree’s pollination system for outcrossing, which is based on automimicry and mass flowering. Co-ordinating editor: S.-M. Chang     

Identification of Scopoletin as a Phytoalexin of the Rubber Tree Hevea brasiliensis1

In leaves of Hevea sp. the production of a blue fluorescing phytoalexin is induced by various fungi. This compound is shown by chromatographic and spectrophotometric means to be scopoletin.     

Growth and yield functions for irrigated plantations of Eucalyptus camaldulensis in the hot desert of India

Eucalyptus camaldulensis forms a major portion of irrigated plantations in the hot desert of India and for effective management of these plantations, growth and yield functions are necessary. This paper describes the development of height, diameter and volume growth functions based on the analysis of the data collected from the permanent sample plots laid out in the study area. The Chapman-Richards equation could be used for the prediction of diameter growth while the Schumacher model could be considered for predicting volume growth. Some base-age variant and invariant site-index models, already reported in the literature, were compared in terms of relative accuracy and it was found that the Payandeh and Wang model performed the best among the four models tried.     

Identification of Tropoelastin as a Ligand for the 65-kD FK506-binding Protein, FKBP65, in the Secretory Pathway

The folding and trafficking of tropoelastin is thought to be mediated by intracellular chaperones, although the identity and role of any tropoelastin chaperone remain to be determined. To identify proteins that are associated with tropoelastin intracellularly, bifunctional chemical cross-linkers were used to covalently stabilize interactions between tropoelastin and associated proteins in the secretory pathway in intact fetal bovine auricular chondrocytes. Immunoprecipitation of tropoelastin from cell lysates after cross-linking and analysis by SDS-PAGE showed the presence of two proteins of ~74 kD (p74) and 78 kD (p78) that coimmunoprecipitated with tropoelastin. Microsequencing of peptide fragments from a cyanogen bromide digest of p78 identified this protein as BiP and sequence analysis identified p74 as the peptidyl-prolyl cis–trans isomerase, FKPB65. The appearance of BiP and FKBP65 in the immunoprecipitations could be enhanced by the addition of brefeldin A (BFA) and N-acetyl-leu-leu-norleucinal (ALLN) to the culture medium for the final 4 h of labeling. Tropoelastin accumulates in the fused ER/Golgi compartment in the presence of BFA if its degradation is inhibited by ALLN (Davis, E.C., and R.P. Mecham. 1996. J. Biol. Chem. 271:3787–3794). The use of BFA and other secretion-disrupting agents suggests that the association of tropoelastin with FKBP65 occurs in the ER. Results from this study provide the first identification of a ligand for an FKBP in the secretory pathway and suggest that the prolyl cis–trans isomerase activity of FKBP65 may be important for the proper folding of the proline-rich tropoelastin molecule before secretion.     

Identification of nobiletin,a polymethoxyflavonoid,as an enhancer of adiponectin secretion

Adiponectin, an adipocyte-derived protein with insulin-sensitizing, anti-diabetic and anti-atherogenic activities, is known to be induced during adipocyte differentiation. Nobiletin, a citrus polymethoxy flavonoid, was found to induce the differentiation of ST-13 preadipocytes into mature adipocytes and enhance the production of adiponectin protein at a concentration of 10 μM.     

Identification of renal cathepsin B as a human prorenin-processing enzyme

Prorenin, the inactive biosynthetic precursor of renin, is proteolytically cleaved in the renal juxtaglomerular cells to renin. The activity of renin is rate-limiting for generation of angiotensin II in the circulation. We identified a renal thiol protease which activates and accurately cleaves the 43-amino acid prosegment of human recombinant prorenin. In the current studies, 6.5 mg of this protease was purified from human renal cortex using a three-step procedure dependent upon Leu-Leu-arginyl affinity chromatography. This represented an overall 766-fold purification and resulted in three protein bands on sodium dodecyl sulfate-polyacrylamide gel electrophoresis of molecular weights 30,000, 25,000, and 24,000. All three bands cross-reacted with an anti-human liver cathepsin B antibody upon immunoblot analysis; electrolution of each band and amino-terminal sequence analysis confirmed that the Mr 30,000 protein was mature cathepsin B and the Mr 25,000 and 24,000 bands were cathepsin B subunits. The pH optimum for the hydrolysis of pure human recombinant prorenin by pure renal cathepsin B was 6, and the Michaelis-Menten constant, Km, of the reaction was 1.4 x 10(-9) M. Immunostaining of human kidney using a sheep anti-human cathepsin B antibody demonstrated the presence of cathepsin B in the juxtaglomerular areas of the kidney, as well as in the renal proximal tubules. Electron microscopic immunohistochemistry using the same antibody demonstrated cathepsin B in dense secretory granules of the juxtaglomerular cells. Renin was also shown to be present in these granules. This study provides both biochemical and morphological evidence that renal cathepsin B is a human prorenin-processing enzyme.     

Changes in peroxidase activity, and level of phenolic compounds during light-induced plantlet regeneration from Eucalyptus camaldulensis Dehn. nodes in vitro

Node cultures of Eucalyptus camaldulensis Dehn inPetri dishes in vitro under darkness in the presence of anauxin developed meristematic agglomerates (4 to 6 diameter),i.e. dense shoot clusters in which outgrowth of numerous successive buds islimited. Similar cultures under a 16 photoperiod produced smallgreen plantlets with reduced leaves often presenting white hypertrophiedlenticels and very short roots crowning the stem bases. The use of half-litreglass vials under light allowed direct development of well-developed rootedplantlets, either in the presence of the same auxin or in the presence of acytokinin. Light favoured an increase in phenolic compounds and a reversevariation of peroxidase activity during the culture cycles. These aspects arediscussed in terms of a possible regulation of the endogenous auxin levelthrough a light control of peroxidase activity and the level of phenoliccompounds.     

Cloning, Expression, and Characterization of Iron Superoxide Dismutase in Sonneratia alba, a Highly Salt Tolerant Mangrove Tree

In this study, a novel iron superoxide dismutase (FeSOD) gene from Sonneratia alba was cloned and then expressed in Escherichia coli Rosetta-gami, designated as SaFeSOD. The DNA sequence of SaFeSOD contained a 786-bp open reading frame which encodes a 261 amino-acid protein of 30.0 kDa. The 651-bp fragment coding for putative mature SaFeSOD was amplified and inserted into pET15b for expression. This recombinant SaFeSOD was subsequently isolated by Ni-trap column protein purification system. The apparent molecular mass of the purified enzyme was 25 kDa on SDS-PAGE. In comparison with FeSODs from other plant species, all iron-binding sites (His 27, His 80, Asp 164 and His 168) of SaFeSOD were conserved. SaFeSOD was found to have good pH stability in the pH range of 3.5–9.5 at 25 °C after 1 h incubation and was relatively stable and showed 78 % activity when incubated in 50 °C for 1 h. Quantitative real-time PCR experiments demonstrated that SaFeSOD was expressed in leaf, stem, flower, fruit and root tissues with the highest expression in leaf tissues.     

Identification of an adaptor-associated kinase, AAK1, as a regulator of clathrin-mediated endocytosis

The mu 2 subunit of the AP2 complex is known to be phosphorylated in vitro by a copurifying kinase, and it has been demonstrated recently that mu 2 phosphorylation is required for transferrin endocytosis (Olusanya, O., P.D. Andrews, J.R. Swedlow, and E. Smythe. 2001. Curr. Biol. 11:896-900). However, the identity of the endogenous kinase responsible for this phosphorylation is unknown. Here we identify and characterize a novel member of the Prk/Ark family of serine/threonine kinases, adaptor-associated kinase (AAK)1. We find that AAK1 copurifies with adaptor protein (AP)2 and that it directly binds the ear domain of alpha-adaptin in vivo and in vitro. In neuronal cells, AAK1 is enriched at presynaptic terminals, whereas in nonneuronal cells it colocalizes with clathrin and AP2 in clathrin-coated pits and at the leading edge of migrating cells. AAK1 specifically phosphorylates the mu subunit in vitro, and stage-specific assays for endocytosis show that mu phosphorylation by AAK1 results in a decrease in AP2-stimulated transferrin internalization. Together, these results provide strong evidence that AAK1 is the endogenous mu 2 kinase and plays a regulatory role in clathrin-mediated endocytosis. These results also lend support to the idea that clathrin-mediated endocytosis is controlled by cycles of phosphorylation/desphosphorylation.