Coumarins from the stems and leaves of Clausena dunniana H. Lév

Phytochemical study on the stems and leaves of Clausena dunniana H. Lév. led to the isolation and identification of 14 coumarins (1–14). Their chemical structures were determined on the basis of MS, NMR, and further supported by comparison with those reported in the literature. This is the first report that compounds 1–2, 4, 8, and 12–14 are present in the genus Clausena, and all of these compounds were isolated from C. dunniana for the first time. The chemotaxonomic significance of these isolated compounds was discussed.     

Transient expression of β-glucuronidase in Arabidopsis thaliana leaves and roots and Brassica napus stems using a pneumatic particle gun

Successful transient expression of -glucuronidase (GUS) in Arabidopsis thaliana leaves and roots and Brassica napus stems was obtained after gene delivery with a pneumatic particle gun driven by compressed air. Effects of the pneumatic pressure used to accelerate the particles (accelerating pressure; 85 to 200 kg/cm²) and of preculture periods of plant tissues (0 to 6 days) on the efficiency of gene delivery were studied. In A. thaliana leaves, best results were obtained at 115 kg/cm² of accelerating pressure and 3 days of preculture. In A. thaliana roots, the optimum was at 200 kg/cm² of accelerating pressure and 3 days of preculture. These results indicate that both preculture period and accelerating pressure are vital factors that determine the efficiency of gene delivery by particle gun.     

Isolation, identification and quantitation of hydroxycinnamic acid conjugates, potential platform chemicals, in the leaves and stems of Miscanthus × giganteus using LC-ESI-MSn

Miscanthus × giganteus is a source of platform chemicals and bioethanol through fermentation. Cinnamates in leaves and stems were analysed by LC–ESI-MSⁿ. Free phenols were extracted and separated chromatographically. More than 20 hydroxycinnamates were identified by UV and LC–ESI-MSⁿ. Comparative LC–MS studies on the leaf extract showed isomers of O-caffeoylquinic acid (3-CQA, 4-CQA and 5-CQA), O-feruloylquinic acid (3-FQA, 4-FQA and 5-FQA) and para-coumaroylquinic acid (3-pCoQA and 5-pCoQA). Excepting 3-pCoQA, all were also detected in stem. 5-CQA dominated in leaf; a mandelonitrile–caffeoylquinic acid dominated in stem. Three minor leaf components were distinguished by fragmentation patterns in a targetted MS² experiment as dicaffeoylquinic acid isomers. Others (M_r 516) were tentatively identified as hexosylcaffeoyl-quinates. Three positional isomers of O-caffeoylshikimic acid were minor components. p-Hydroxybenzaldehyde was also a major component in stem. This is the first report of the hydroxycinnamic acid profile of leaves and stems of M. × giganteus.     

In vitro culture of vanhoutte's spirea explants from ‘secondary cultures’ and dormant stems forced in solutions containing plant growth regulators

Explants from new growth of forced dormant stems and secondary cultures of Vanhoutte's spirea were cultured on Linsmaier and Skoog (L.S.) medium containing benzyladenine (BA), indoleacetic acid (IAA), thidiazuron (TDZ), and zeatin. The dormant stems were forced by immersing their basal portions in forcing solutions containing 626 µM 8-hydroxyquinoline citrate (8-HQC) and 2% sucrose. BA and gibberellic acid (GA₃) were also added into the forcing solutions to determine if explants obtained from the new growth will benefit from this treatment when culturedin vitro.L.S. medium supplemented with 5 µM BA alone, 5 µM BA plus 1 or 5 µM IAA, and 0.5 or 0.75 µM TDZ alone produced the best shoot proliferation for both sources of explants. BA and GA₃ appeared to be taken up from the forcing solution by the new softwood growth. BA in the forcing solution stimulatedin vitro shoot proliferation in different degrees depending on the period of treatment, while GA₃ caused lessin vitro shoot proliferation. It is proposed that forcing solutions containing plant growth regulators (P.G.R.) are a useful approach for manipulating responses of plant tissues culturedin vitro.     

Piperhancosides A−C,new lignan glycosides from the stems of Piper hancei Maxim

Three new lignan glycosides, piperhancosides A−C (1−3), and two known compounds (4−5) were isolated from the n-BuOH extract of the stems of Piper hancei Maxim. The planar structures of the new compounds were elucidated by extensive spectroscopic analyses. Their relative and absolute configurations were determined by coupling constants, chemical shift differences, acid hydrolysis, enzymatic hydrolysis, and experimental ECD spectra. All the isolates were evaluated for their antineuroinflammatory and antioxidant activities, and compounds 4 and 5 showed significant DPPH.+ radical scavenging ability with EC₅₀ value of 14.07 and 16.48 μM, respectively.     

Chimpanzees detect ant-inhabited dead branches and stems: a study of the utilization of plant–ant relationships in the Mahale Mountains, Tanzania

Chimpanzees in the Mahale Mountains of Tanzania consume several species of stem- and branch-inhabiting ants throughout the year, without tools. Those ants are cryptic species, and it was unknown how to find them constantly. There has been little research on how the chimpanzees locate these ants. In this study, I use behavioral observations of the chimpanzee predators and surveys of the ant fauna and plants across different habitats to test the hypothesis that chimpanzees use plant species as a cue to efficiently locate ant colonies in litter units (dead parts of the plant). Ants were found to be associated with live plants and with spaces within litter units which provide nesting places. Such ant–plant litter relationships were not necessarily as strong as the mutualism often observed between live plants and ants. The proportion of available litter units inhabited by ants was 20 %, and litter units of three plant species (Vernonia subligera, Dracaena usambarensis, and Senna spectabilis) were well occupied by ants in the home range of the chimpanzees. The ant-inhabited ratio in chimpanzee-foraged litter units was higher than that in the available units in the home range. Chimpanzees fed more often on Crematogaster spp. than on other resident ants and at a higher rate than expected from their occurrence in the litter units. Above three plant species were well occupied by Crematogaster sp. 3 or C. sp. 18. It is concluded that chimpanzees locate ants by selecting litter units of plant species inhabited by ants.     

What happens when stems are embolized in a centrifuge? Testing the cavitron theory

Vulnerability curves (VCs) measure the ability of vessels to retain metastable water without embolisms that lower the hydraulic conductivity of stems. The fastest method of measuring VCs is the centrifuge technique and the Cochard cavitron is a method that allows measurement of hydraulic conductivity of stems while they are spinning. This paper describes the pattern of embolism that results after spinning the stems of hybrid aspen (Populus tremula×P. tremuloides) and two hybrid cottonwoods (P38P38 P. balsamifera×P. simonii and Northwest, which is a hybrid of P. deltoides×P. balsamifera). It is recognized that the pattern of embolism induced in a centrifuge ought to differ from the pattern during natural dehydration of plants because the profiles of tension vs distance greatly differ under the two modes of inducing stress. The pattern of embolism was visualized by a staining technique and quantified by traditional measurements of percentage loss conductivity (PLC) performed on subsample segments excised from spun stems. We found a pattern of embolism approximating that expected from theory: (1) PLC near the axis of rotation exceeded the average; (2) PLC was quite high near the ends of the stems, even though tension ought to be zero; (3) large vessels cavitated before small vessels; (4) more embolism occurred near the base than near the apex of the stems. However, we could not always scale up from subsample conductivity and PLC to whole‐stem conductivity. This pattern of embolism is interpreted in terms of vessel diameter and vessel length.     

Maplexins, new α-glucosidase inhibitors from red maple (Acer rubrum) stems

Thirteen gallic acid derivatives including five new gallotannins, named maplexins A-E, were isolated from red maple (Acer rubrum) stems. The compounds were identified by spectral analyses. The maplexins varied in number and location of galloyl groups attached to 1,5-anhydro-d-glucitol. The isolates were evaluated for α-glucosidase inhibitory and antioxidant activities. Maplexin E, the first compound identified with three galloyl groups linked to three different positions of 1,5-anhydro-d-glucitol, was 20 fold more potent than the α-glucosidase inhibitory drug, Acarbose (IC(50)=8 vs 160 μM). Structure-activity related studies suggested that both number and position of galloyls attached to 1,5-anhydro-d-glucitol were important for α-glucosidase inhibition.     

Are pacemaker properties required for respiratory rhythm generation in adult turtle brain stems in vitro?

The role of pacemaker properties in vertebrate respiratory rhythm generation is not well understood. To address this question from a comparative perspective, brain stems from adult turtles were isolated in vitro, and respiratory motor bursts were recorded on hypoglossal (XII) nerve rootlets. The goal was to test whether burst frequency could be altered by conditions known to alter respiratory pacemaker neuron activity in mammals (e.g., increased bath KCl or blockade of specific inward currents). While bathed in artificial cerebrospinal fluid (aCSF), respiratory burst frequency was not correlated with changes in bath KCl (0.5-10.0 mM). Riluzole (50 microM; persistent Na(+) channel blocker) increased burst frequency by 31 +/- 5% (P < 0.05) and decreased burst amplitude by 42 +/- 4% (P < 0.05). In contrast, flufenamic acid (FFA, 20-500 microM; Ca(2+)-activated cation channel blocker) reduced and abolished burst frequency in a dose- and time-dependent manner (P < 0.05). During synaptic inhibition blockade with bicuculline (50 microM; GABA(A) channel blocker) and strychnine (50 muM; glycine receptor blocker), rhythmic motor activity persisted, and burst frequency was directly correlated with extracellular KCl (0.5-10.0 mM; P = 0.005). During synaptic inhibition blockade, riluzole (50 microM) did not alter burst frequency, whereas FFA (100 microM) abolished burst frequency (P < 0.05). These data are most consistent with the hypothesis that turtle respiratory rhythm generation requires Ca(2+)-activated cation channels but not pacemaker neurons, which thereby favors the group-pacemaker model. During synaptic inhibition blockade, however, the rhythm generator appears to be transformed into a pacemaker-driven network that requires Ca(2+)-activated cation channels.     

Does growth correlate with turgor-induced elastic strain in stems? A re-evaluation of de Vries' classical experiments

The correlation between growth and turgor-induced elastic expansion was studied in hypocotyls of sunflower (Helianthus annuus) seedlings under various growth conditions. Turgor-induced elastic cell wall strain was greater in hypocotyls of faster growing seedlings, i.e. in etiolated versus light-grown ones. It also was higher in rapidly growing young seedlings as compared with nongrowing mature ones. However, analysis of the spatial distribution of elastic strain and growth demonstrated that their correspondence was only apparent. Profiles of elastic strain declined steadily from the top of the hypocotyls toward the basis, whereas the profiles of relative elemental growth rate along the hypocotyls showed maxima within the growing zones. In contrast to earlier hypotheses, we conclude that turgor-induced elastic cell wall strain and growth do not correlate precisely in growing hypocotyls.     

Variation in xylem structure and function in roots and stems of scion–rootstock combinations of sweet cherry tree (<Emphasis Type="Italic">Prunus avium</Emphasis> L.)

To assess hydraulic architecture and limitations to water transport across scion–rootstock combinations (Prunus avium L. cultivar Van grafted on five differing size-controlling rootstocks: P. avium (vigorous) > CAB 11E > Maxma 14 > Gisela 5 > Edabriz (dwarfing)), we compared xylem anatomy, and calculated relative hydraulic conductivity (RC) and vulnerability index (VI) of roots (small, medium and large diameter) and stems. Water relations, leaf gas exchange and variations in growth were also determined. Roots exhibited larger-diameter xylem conduits (VD), greater RC and VI than stems in all Van–rootstock combinations. Moreover, there was a significantly higher vessel frequency (VF), lower VD, RC and VI in dwarfed trees, especially grafted on Gisela 5 than trees on the invigorating rootstocks, P. avium L., CAB 11E and Maxma 14. Anatomical constraints on water status imposed by the smaller VD (and/or in lower xylem thickness and root system length) of dwarfed trees imply a series of negative feedbacks, like a decrease in RC, stem water potential, leaf gas exchange and growth. On the other hand, Van grafted on CAB 11E and Maxma 14, with wide vessels and high VI, could be more susceptible to embolism, especially during periods of severe water stress, than trees on dwarfing rootstocks, which had small vessels and low VI.     

Distribution and properties of a ‘lectin- like’ glycoprotein from leaves and stems of<Emphasis Type="Italic">Dolichos biflorus</Emphasis>: Implications on the role of lectins in plants

Cardiotoxin II of the Indian cobra(Naja naja) contains approximately four Mg²⁺ per mol. Complete demetallation of the toxin is achieved by three cycles of treatment with ethylenediamine tetraacetate and gel filtration. Reconstitution of toxin by treatment of the apo-protein with Mg²⁺ restores metal content and inorganic pyrophosphatase activity only to the extent of two atoms/mol and 65%, respectively. Use of Mg (II)-EDTA in the reconstitution experiment yields restoration of half the original enzyme activity. Mg²⁺ is required for the inorganic pyrophosphatase action of the toxin. A definitive statement on the non-essentiality of Mg²⁺ for the lethal toxicity of the toxin is not possible at present, although experimental observations indicate that demetallated toxin is as toxic as the native toxin. Based on this and the differing sensitivities of the enzyme and toxic activities of the toxin to heat, it is suggested that the reaction centres in the toxin for the two activities are different and that the pyrophosphatase activity is not causally connected with the lethal toxicity of the toxin     

Fructan 1-exohydrolases. beta-(2,1)-trimmers during graminan biosynthesis in stems of wheat? Purification,characterization, mass mapping,and cloning of two fructan 1-exohydrolase isoforms

Graminan-type fructans are temporarily stored in wheat (Triticum aestivum) stems. Two phases can be distinguished: a phase of fructan biosynthesis (green stems) followed by a breakdown phase (stems turning yellow). So far, no plant fructan exohydrolase enzymes have been cloned from a monocotyledonous species. Here, we report on the cloning, purification, and characterization of two fructan 1-exohydrolase cDNAs (1-FEH w1 and w2) from winter wheat stems. Similar to dicot plant 1-FEHs, they are derived from a special group within the cell wall-type invertases characterized by their low isoelectric points. The corresponding isoenzymes were purified to electrophoretic homogeneity, and their mass spectra were determined by quadrupole-time-of-flight mass spectrometry. Characterization of the purified enzymes revealed that inulin-type fructans [beta-(2,1)] are much better substrates than levan-type fructans [beta-(2,6)]. Although both enzymes are highly identical (98% identity), they showed different substrate specificity toward branched wheat stem fructans. Although 1-FEH activities were found to be considerably higher during the fructan breakdown phase, it was possible to purify substantial amounts of 1-FEH w2 from young, fructan biosynthesizing wheat stems, suggesting that this isoenzyme might play a role as a beta-(2,1)-trimmer throughout the period of active graminan biosynthesis. In this way, the species and developmental stage-specific complex fructan patterns found in monocots might be determined by the relative proportions and specificities of both fructan biosynthetic and breakdown enzymes.     

Seasonal changes in the efflux of sugars from parenchyma cells into the apoplast in poplar stems (Populus × canademis “robusta”)

Summary The efflux of sugars from parenchyma cells into the apoplast has been studied in the wood of Populus × canadensis robusta in relation to the sugar level of the tissue and the sugar content of the tracheal sap during all physiological stages of the year. In poplar, the spring maximum in sugar content of the tracheal sap is clearly not the result of continuous exosmosis during winter but is reached within a short period in spring. The seasonal patterns of starch and sugar content of the wood and of the sugar content of the tracheal sap are described. The efflux of sugars from tissue sections changes drastically over the year, i.e., from 0.3 to 8.3 g mg^–1DWT day^–1. In general, it is high in fall and winter, and low during late spring and summer. However, high tissue sugar levels proved not always to be correlated with high efflux rates or with high sugar levels in the tracheal sap, indicating that the intracellular compartmentalization of sugars, their passive and catalysed release into, and their re-uptake from the apoplast are all essentially involved in determining the actual sugar content of the sap. Sucrose, which is the dominant sugar in the tracheal sap during winter (pH 7.0–7.5) and in the efflux experiments at pH 7.5, in contrast to the hexoses which prevail in the spring sap (pH around 5.5) and also in the efflux experiments at pH 5.6, is considered to be preferentially released in poplar and to become extraplasmatically hydrolysed. The reasons for tree-specific differences are discussed.     

Syntheses and spectroscopic properties of α- and β-phosphatidylcholines and phosphatidylethanolamines

The widely used partial synthesis of phospholipids via deacylation of naturally occurring phospholipids, followed by reacylation with fatty acid anhydrides, is accompanied by phosphoryl migration. The resulting mixture of α- and β-phospholipids was separated by short-column chromatography. Milder acylation procedures in which no phosphoryl migration occurs, were developed. 1,2-Dilinoleoyl-sn-glycero-3-phosphocholine was prepared in 50% yield by acylation of sn-glycero-3-phosphocholine (GPC) with N-linoleoylimidazole. Detailed NMR and infrared spectra of α- and β-phosphatidylcholines (PCs) and -ethanolamines (PEs) are reported and the differences between isomers discussed.     

Phenotypic plasticity and longevity in plants and animals: cause and effect?

Immobile plants and immobile modular animals outlive unitary animals. This paper discusses competing but not necessarily mutually exclusive theories to explain this extreme longevity, especially from the perspective of phenotypic plasticity. Stem cell immortality, vascular autonomy, and epicormic branching are some important features of the phenotypic plasticity of plants that contribute to their longevity. Monocarpy versus polycarpy can also influence the kind of senescent processes experienced by plants. How density-dependent phenomena affecting the establishment of juveniles in these immobile organisms can influence the evolution of senescence, and consequently longevity, is reviewed and discussed. Whether climate change scenarios will favour long-lived or short-lived organisms, with their attendant levels of plasticity, is also presented.     

Dogmatisms and Catechisms — Ethics and Companion Animals

Abstract

The current reconsideration of the place in nature of human beings unfortunately continues to be an acrimonious one. All too often the debate is more akin to a warlike encounter where each side attempts to gain control or the upper hand than a search for points of agreement. Given this context, it is important to entertain views that emanate from different cultural traditions as a way to infuse the debate with new life. Students of Native American culture have consistently pointed out that the essential concepts of life balance and reciprocity represented there may serve as useful points of consideration as we struggle with the appropriate relationships with animals and nature. This article presents a representative Zuni story, told by Governor Robert E. Lewis, that illustrates these notions.