[Studies on the constituents of flowers. IV. On the components of the flower of Cornus controversa Hemsl (author's transl)].
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Oils, Volatile↗
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Corni fructus as the major herb of Die-Huang-Wan for lowering plasma glucose in Wistar rats.
Die-Huang-Wan is a mixture of six herbs used to lower plasma glucose by increasing insulin secretion in normal rats. Die-Huang-Wan contains the herbs dioscorea (Dioscoreae rhizoma), cornus (Corni fructus), alisma (Rhizoma alismatis), holelen (Poria), rehmannia (Rehmanniae radix) and tree peony bark (Moutan radicis cortex). The present study was designed to clarify the major herb contributing to the plasma glucose-lowering action of Die-Huang-Wan in rats. A decrease in plasma glucose was not observed in Wistar rats treated with the cornus-deleted formula of Die-Huang-Wan; however, the action was retained in the other herb-deleted formulas containing cornus. In normal rats, the decrease in plasma glucose and increase in plasma insulin concentrations were dependent on the dose of cornus and were similar to those produced by Die-Huang-Wan. Treatment of Wistar rats with each of the other five herbs separately did not result in a decrease in plasma glucose. Moreover, the increase in plasma insulin or reduction in plasma glucose resulting from cornus treatment was blocked by atropine or 4-diphenylacetoxy-N-methylpiperidine methiodide mustard, indicating mediation of muscarinic M(3) receptors similar to that caused by Die-Huang-Wan. These results suggest that cornus is the major contributor to the plasma glucose-lowering action in Die-Huang-Wan in normal rats.
Animals↗
Timing the eastern Asian-eastern North American floristic disjunction: molecular clock corroborates paleontological estimates.
Sequence data of the chloroplast gene rbcL were used to estimate the time of the well-known eastern Asian-eastern North American floristic disjunction. Sequence divergence of rbcL was examined for 22 species of 11 genera (Campsis, Caulophyllum, Cornus, Decumaria, Liriodendron, Menispermum, Mitchella, Pachysandra, Penthorum, Podophyllum, and Phryma) representing a diverse array of flowering plants occurring disjunctly in eastern Asia and eastern North America. Divergence times of putative disjunct species pairs were estimated from synonymous substitutions, using rbcL molecular clocks calibrated for Cornus. Relative rate tests were performed to assess rate constancy of rbcL evolution among lineages. Corrections of estimates of divergence times for each species pair were made based on rate differences of rbcL between Cornus and other species pairs. Results of these analyses indicate that the time of divergence of species pairs examined ranges from 12.56 +/- 4.30 million years to recent (<0.31 million years), with most within the last 10 million years (in the late Miocene and Pliocene). These results suggest that the isolation of most morphologically similar disjunct species in eastern Asia and eastern North America occurred during the global climatic cooling period that took place throughout the late Tertiary and Quaternary. This estimate is closely correlated with paleontological evidence and in agreement with the hypothesis that considers the eastern Asian-eastern North American floristic disjunction to be the result of the range restriction of a once more or less continuously distributed mixed mesophytic forest of the Northern Hemisphere that occurred during the late Tertiary and Quaternary. This implies that in most taxa the disjunction may have resulted from vicariance events. However, long-distance dispersal may explain the disjunct distribution of taxa with low divergence, such as Menispermum.
Asia↗
RESEARCH: Shrub Propagation Techniques for Biological Control ofInvading Tree Species
/ The use of relatively stable shrub communities to control invasionby trees could be an efficient way of reducing herbicide applications, andthus represents an environmental gain, in areas such as rights-of-way. Thequestion is how to favor the expansion of these relatively stable shrubcommunities using different propagation techniques. Three experimentaltreatments, cutting back, layering, and cutting back-layering were performedon Cornus stolonifera, Salix petiolaris, and Spiraea albaclones already located within the corridor of an electrical power line. Toestablish the efficiency of treatments, we examined the statisticaldifferences of growth traits between species and treatments.An analysis of the effects of layering shows, after the first growth season,differences for all growth traits in only one species, Spiraea alba.After the second growth season, we observed the development of new aerialstems. Layering favors horizontal expansion of shrubs over heightdevelopment. The third year after treatment, the effect of layering isreduced except for Cornus stolonifera, which continuously increases,as shown by the significant progression of the clone issued from the layereven five years after treatments. With the cutting back technique, weexpected a distinct vertical growth of the shrubs at the expense ofincreasing the crown diameter. This technique would be best associated withthe rejuvenation of clones, followed by a layering of new shoots to allow ahorizontal expansion of the shrubs. Therefore, the formation of a dense shrubcommunity by layering should be considered a valuable approach for thebiological control of undesirable trees in powerline rights-of-way.KEY WORDS: Layering; Cutting back; Right-of-way; Cornus stolonifera;Salix petiolaris; Spiraea alba; Quebec
Journal Article↗
Phytochrome control of growth cessation and initiation of cold acclimation in selected woody plants.
Short day enhancement of cold acclimation in twigs of Cornus (red-osier dogwood), Weigela, and Pyracantha (firethorn) was studied using dark interruptions with red or with red-far red radiation. Hardiness was estimated by freezing stem tissues to preselected temperatures and evaluating injury electrolytically. Dark-period interruptions with red radiation suppressed cold acclimation in Cornus and Weigela. When red light was followed by far red light, suppression was relieved. No radiation control of acclimation was found with Pyracantha. The short day enhancement of cold acclimation in Cornus and Weigela appears to be phytochrome-mediated.
Journal Article↗
The eastern Asian and eastern and western North American floristic disjunction: congruent phylogenetic patterns in seven diverse genera.
One of the most remarkable examples of intercontinental disjunction of the North Temperate Flora involves eastern Asia and eastern and western North America. Although there has been considerable interest in this phytogeographic pattern for over 150 years (e.g., Gray, 1859; Li, 1952; Graham, 1972; Boufford and Spongberg, 1983; Wu, 1983; Tiffney, 1985a, 1985b), relationships among taxa displaying the disjunction remain obscure. Understanding phylogenetic relationships is, however, a prerequisite for historical biogeographic analyses of this distributional pattern. To understand better the relationships of taxa displaying this intercontinental disjunction, phylogenetic analyses were conducted using a variety of DNA data sets for species of four genera (Cornus, Boykinia, Tiarella, and Trautvetteria) that occur in eastern Asia, eastern North America, and western North America. An area cladogram was constructed for each of the four genera, all of which show a similar pattern of relationship: the eastern Asian species are sister to all North American species. An identical phylogenetic pattern is also found in three other taxa exhibiting this disjunction (Aralia sect. Aralia, Calycanthus, and Adiantum pedatum). The congruent phylogenetic pattern found in these seven diverse genera raises the possibility of a common origin of the eastern Asia, eastern and western North America disjunction. The data are in agreement with the long-standing hypothesis that this well-known floristic disjunction represents the fragmentation of a once continuous Mixed Mesophytic forest community and suggest that the disjunction may have involved only two major vicariance events: an initial split between Eurasia and North America, followed by the isolation of floras between eastern and western North America. However, congruence between phylogenies and geographic distributions does not necessarily indicate an identical phytogeographic history. Taxa exhibiting the same phylogenetic pattern may have originated at different geological times. Analysis of divergence times using the molecular clock indicates that species of Cornus, Boykinia, and Calycanthus may have diverged at different geological times, suggesting that the floristic disjunction involving eastern Asia and North America may not be simple; it may have involved multiple historical events at very different geological times in different genera.
Asia, Eastern↗
Relationships within Cornales and circumscription of Cornaceae-matK and rbcL sequence data and effects of outgroups and long branches.
Phylogenetic relationships in Cornales were assessed using sequences rbcL and matK. Various combinations of outgroups were assessed for their suitability and the effects of long branches and outgroups on tree topology were examined using RASA 2.4 prior to conducting phylogenetic analyses. RASA identified several potentially problematic taxa having long branches in individual data sets that may have obscured phylogenetic signal, but when data sets were combined RASA no longer detected long branch problems. t(RASA) provides a more conservative measurement for phylogenetic signal than the PTP and skewness tests. The separate matK and rbcL sequence data sets were measured as not containing phylogenetic signal by RASA, but PTP and skewness tests suggested the reverse [corrected]. Nonetheless, the matK and rbcL sequence data sets suggested relationships within Cornales largely congruent with those suggested by the combined matK-rbcL sequence data set that contains significant phylogenetic signal as measured by t(RASA), PTP, and skewness tests. Our analyses also showed that a taxon having a long branch on the tree may not be identified as a "long-branched" taxon by RASA. The long branches identified by RASA had little effect on the arrangement of other taxa in the tree, but the placements of the long-branched taxa themselves were often problematic. Removing the long-branched taxa from analyses generally increased bootstrap support, often substantially. Use of non-optimal outgroups (as identified by RASA) decreased phylogenetic resolution in parsimony analyses and suggested different relationships in maximum likelihood analyses, although usually weakly supported clades (less than 50% support) were impacted. Our results do not recommend using t(RASA) as a sole criterion to discard data or taxa in phylogenetic analyses, but t(RASA) and the taxon variance ratio obtained from RASA may be useful as a guide for improved phylogenetic analyses. Results of parsimony and ML analyses of the sequence data using optimal outgroups suggested by RASA revealed four major clades within Cornales: (1) Curtisia-Grubbia, (2) Cornus-Alangium, (3) Nyssa-Camptotheca-Davidia-Mastixia-Diplopanax, and (4) Hydrangeaceae-Loasaceae, with clades (2) and (3) forming a monophyletic group sister to clade (4) and clade (1) sister to the remainder of Cornales. However, there was not strong bootstrap support for relationships among the major clades. The placement of Hydrostachys could not be reliably determined, although most analyses place the genus within Hydrangeaceae; ML analyses, for example, placed the genus as the sister of Hydrangeeae. Our results supported a Cornales including the systematically problematic Hydrostachys, a Cornaceae consisting of Cornus and Alangium, a Nyssaceae consisting of Nyssa and Camptotheca, a monogeneric Davidiaceae, a Mastixiaceae consisting of Mastixia and Diplopanax, and an expanded Grubbiaceae consisting of Grubbia and Curtisia, and two larger families, Hydrangeaceae and Loasaceae.
Cornaceae↗
Water relations of several hardwood species in response to throughfall manipulation in an upland oak forest during a wet year.
We investigated the effects of altered precipitation on leaf osmotic potential at full turgor (Psi(pio)) of several species in an upland oak forest during the 1994 growing season as part of a Throughfall Displacement Experiment at the Walker Branch Watershed near Oak Ridge, Tennessee. The main species sampled included overstory chestnut oak (Quercus prinus L.), white oak (Q. alba L.), red maple (Acer rubrum L.); intermediates sugar maple (A. saccharum L.) and blackgum (Nyssa sylvatica Marsh.); and understory dogwood (Cornus florida L.) and red maple. The precipitation treatments were: ambient precipitation; ambient minus 33% of throughfall (dry); and ambient plus 33% of throughfall (wet). Except in late September, midday leaf water potentials (Psi(l)) were generally high in all species in all treatments, ranging from -0.31 to -1.34 MPa for C. florida, -0.58 to -1.51 MPa for A. rubrum, and -0.78 to -1.86 MPa for Q. prinus. Both treatment and species differences in Psi(pio) were evident, with oak species generally exhibiting lower Psi(pio) than A. saccharum, A. rubrum, C. florida, and N. sylvatica. The Psi(pio) of C. florida saplings declined in the dry treatment, and Q. prinus, Q. alba, and A. saccharum all exhibited a declining trend of Psi(pio) in the dry treatment, although Psi(pio) of Q. prinus leaves increased in late August, corresponding to a recovery in soil water potential. Cornus florida exhibited osmotic adjustment with the largest adjustment coinciding with the period of lowest soil water potential in June. The only other species to exhibit osmotic adjustment was Q. prinus, which also maintained a lower baseline Psi(pio) than the other species. We conclude that a 33% reduction of throughfall is sufficient both to alter the water relations of some species in the upland oak forest and to enable the identification of those species capable of osmotic adjustment to a short-term drought during a wet year.
Journal Article↗
Freezing stress response in woody tissues observed using low-temperature scanning electron microscopy and freeze substitution techniques.
The objective of the current research was to examine the response of woody plant tissues to freezing stress by using scanning electron microscopy (SEM). Nonsupercooling species red osier dogwood (Cornus stolonifera Michx.), weeping willow (Salix babylonica L.), and corkscrew willow (Salix matsudana Koidz. f. tortuosa Rehd.) survived freezing stress as low as -60 degrees C. Cell collapse of ray parenchyma cells of these species was expected but did not occur. It was concluded that ray parenchyma cells of these species do not fit into either the supercooling or extracellular freezing classifications. Tissues from flowering dogwood (Cornus florida L.), apple (Malus domestica Borkh. cv "Starking III"), red oak (Quercus rubra L.), scarlet oak (Quercus coccinea Muench.), and red ash (Fraxinus pennsylvanica Marsh) were confirmed as supercooling species, and did not survive exposures below -40 degrees C. Ray parenchyma cells of these species did not collapse in response to freezing stress, as was expected. Cell collapse along the margins of voids were observed in bark of all seven species. Voids were the result of extracellular ice crystals formed in the bark during exposure to freezing stress. Tissues prepared by freeze substitution techniques were found to be adequately preserved when compared to those prepared by conventional fixation and low temperature SEM techniques. A freezing protocol for imposing freezing stress at temperatures lower than experienced naturally in the area where the study was conducted was developed that produced responses comparable to those observed in specimens collected in the field during natural freezing events.
Journal Article↗
Sequence signatures from DNA amplification fingerprints reveal fine population structure of the dogwood pathogen Discula destructiva.
Isolates of Discula destructiva Redlin and an undescribed species of Discula, the filamentous fungi that cause anthracnose of flowering (Cornus florida L.) and Pacific (Cornus nuttalli Aud.) dogwoods, were analyzed for genetic variation by nucleic acid scanning with arbitrary mini-hairpin oligonucleotide primers. While the fungal population was highly homogeneous throughout the disease range in eastern and western North America, the generation of arbitrary signatures from amplification profiles (ASAP) distinguished isolates from the northeast, middle and southern Appalachian mountain range, and western United States and Canada. ASAP involves a dual-step arbitrary primer-based amplification procedure that generates a large number of informative allelic characters by amplification of monomorphic DNA fingerprints. ASAP analyses showed a fine fungal population structure consistent with the recent and separate introduction of the pathogen on the west and east coasts of North America.
Algorithms↗
Liu-wei-dihuang: a study by pulse analysis.
Pulse analysis method was used in studying the traditional Chinese formula Liu-Wei-Dihuang as well as five of its main components (Rehmannia glutinosa, Cornus officinalis, Paeonia Suffruticosa, Poria cocos and Alisma plantogo-aquatica var oriental). Based on our recently developed resonance theory, we tried to elucidate the mechanism and mutual reactions of these meridian related herbs. Hot water herbal extracts were injected intraperitoneally into rats and the pressure pulse spectrum at the caudate artery was measured. The results of this study indicated that Liu-Wei-Dihuang mildly increased blood flow to meridians with lower resonance frequency: namely the liver C1, the kidney C2 and the spleen C3; but decreased blood flow to the higher resonance frequency organs and meridians: the lung C4, the stomach C5, the gall bladder C6, and the bladder C7. It also decreased the heart load C0. All of the five herb components increased blood flow to the kidney C2 and the spleen C3; but their effects on the high frequency organs varied. Alisma plantogo-aquatica var. oriental decreased the C0, C5, C6, C7; Poria cocos decreased C1, C4, C5, C6; Rehmannia glutinosa, Paeonia Suffruticosa decreased C0, C4, C5, C6, C7; Cornus officinalis increased C4 but decreased C0, C5, C6, C7.
Animals↗
Eltoprazine suppresses hyperpolarizing responses to serotonin in rat hippocampus.
In this study we report the effects of eltoprazine, a phenylpiperazine derivative with high affinity for 5-hydroxytryptamine1 (5HT1) binding sites, on membrane properties of hippocampal neurons. Intracellular recordings were made from cornus ammoni-1 pyramidal neurons in rat hippocampal slices. Responses to eltoprazine were compared with 5HT-induced responses. Superfusion with 5HT induced a dose-dependent hyperpolarization of the membrane accompanied by a resistance decrease. Eltoprazine evoked membrane changes that were similar to but much weaker than those induced by 5HT. Both the 5HT- and eltoprazine-evoked membrane hyperpolarizations were largely suppressed in the presence of spiperone. The eltoprazine-induced effects persisted in the presence of tetrodotoxin and tetraethylammonium and also when haloperidol and phentolamine were added to the medium, indicating that the small agonistic effects of eltoprazine are not due to an indirect activation of dopamine or alpha adrenergic receptors. Superfusion with eltoprazine furthermore resulted in a marked reduction of the response to concomitantly applied 5HT. Dose-response curves for 5HT were shifted to the right in the presence of eltoprazine, while the maximal response was diminished. Hyperpolarizations induced by baclofen, which presumably activates the same K+ conductance as 5HT, were not significantly reduced by eltoprazine. Our data, added to the previously demonstrated high affinity of eltoprazine for 5HT1 sites, suggest that in the hippocampal cornus ammoni-1 area eltoprazine acts as a partial 5HT1 agonist with a relatively low intrinsic activity but a considerable potency to suppress hyperpolarizing responses to 5HT.
Aggression↗
The diversity of polyprenol pattern in leaves of fruit trees belonging to Rosaceae and Cornaceae.
The polyprenol pattern in leaves of fruit trees belonging to the Rosaceae (genera: Prunus, Malus) and Cornaceae (genus: Cornus) families is presented. The content of polyprenyl acetates varied within plant species between 10-50 mg per gram of dry weight. In genus Prunus, Cornus and in representatives of species Malus domestica, a mixture of polyprenols composed of 18, 19, 20, 21 isoprene units was found. In six species of genus Prunus (sour-cherry): P. serrulata-spontanea, P. yedoensis, P. fruticosa. P. kurilensis, P. subhirtella and P. incisa the presence of a second polyprenol family, i.e. the group of prenologues consisting of prenol -35, -36, -37, etc. up to -42 was detected.
Chromatography, High Pressure Liquid↗
Two- and three-dimensional mapping of the iron distribution in the apoplastic fluid of plant leaf tissue by means of magnetic resonance imaging.
A three-dimensional nuclear magnetic resonance imaging (MRI) technique for non-invasive mapping of iron in the apoplastic fluid of plant compartments was developed. The new technique was applied to a leaf of red stem dogwood (Cornus stolonifera). The results are compared with MRI measurements of iron distributions in two dimensions and with total reflection X-ray fluorescence results.
Calibration↗
Botany: a record-breaking pollen catapult.
The release of stored elastic energy often drives rapid movements in animal systems, and plant components employing this mechanism should be able to move with similar speed. Here we describe how the flower stamens of the bunchberry dogwood (Cornus canadensis) rely on this principle to catapult pollen into the air as the flower opens explosively. Our high-speed video observations show that the flower opens in less than 0.5 ms--to our knowledge, the fastest movement so far recorded in a plant.
Cornus↗
Postzygotic isolating factor in sympatric speciation in Rhagoletis flies: reduced response of hybrids to parental host-fruit odors.
Rhagoletis pomonella is a model for sympatric speciation (divergence without geographic isolation) by means of host-plant shifts. Many Rhagoletis species are known to use fruit odor as a key olfactory cue to distinguish among their respective host plants. Because Rhagoletis rendezvous on or near the unabscised fruit of their hosts to mate, behavioral preferences for fruit odor translate directly into premating reproductive isolation among flies. Here, we report that reciprocal F(1) hybrids between the apple and hawthorn host races of R. pomonella, as well as between the host races and an undescribed sibling species infesting Cornus florida (flowering dogwood) do not respond to host fruit volatiles in wind-tunnel assays at doses that elicit maximal directed flight in parental flies. The reduced ability of hybrids to orient to fruit volatiles could result from a conflict between neural pathways for preference and avoidance behaviors, and it suggests that hybrids might suffer a fitness disadvantage for finding fruit in nature. Therefore, host-specific mating may play a dual role as an important postzygotic as well as a premating reproductive barrier to isolate sympatric Rhagoletis flies.
Animals↗
A six-year study of sapling and large-tree growth and mortality responses to natural and induced variability in precipitation and throughfall.
Global climatic change may cause changes in regional precipitation that have important implications for forest growth in the southern United States. In 1993, a stand-level experiment was initiated on Walker Branch Watershed, Tennessee, to study the sensitivity of forest saplings and large trees to changes in soil water content. Soil water content was manipulated by gravity-driven transfer of precipitation throughfall from a dry treatment plot (-33%) to a wet treatment plot (+33%). A control plot was included. Each plot was 6400 m2. Measurements of stem diameter and observations of mortality were made on large trees and saplings of Acer rubrum L., Cornus florida L., Liriodendron tulipifera L., Nyssa sylvatica Marsh, Quercus alba L. and Quercus prinus L. every 2 weeks during six growing seasons. Saplings of C. florida and A. rubrum grew faster and mortality was less on the wet plot compared with the dry and control plots, through 6 years of soil water manipulation. Conversely, diameter growth of large trees was unaffected by the treatments. However, tree diameter growth averaged across treatments was affected by year-to- year changes in soil water status. Growth in wet years was as much as 2-3 times greater than in dry years. Relationships between tree growth, phenology and soil water potential were consistent among species and quantitative expressions were developed for application in models. These field growth data indicate that differences in seasonal patterns of rainfall within and between years have greater impacts on growth than percentage changes in rainfall applied to all rainfall events.
Climate↗
Solute accumulation of chestnut oak and dogwood leaves in response to throughfall manipulation of an upland oak forest.
To determine the biochemical basis of osmotic adjustment, seasonal and treatment differences in foliar water- soluble organic solutes and inorganic ions were investigated for two hardwood species that exhibited osmotic adjustment in a Throughfall Displacement Experiment at the Walker Branch Watershed near Oak Ridge, Tennessee. Leaf samples of overstory and understory chestnut oak (Quercus prinus L.) and understory dogwood (Cornus florida L.) were collected during the 1994 (wet) and 1995 (dry) growing seasons from each of three treatments: dry (-33% throughfall), ambient (control) and wet (+33% throughfall). Foliar soluble carbohydrates and organic acids were measured by gas chromatography-mass spectrometry. During May 1994, when the demand for sucrose was greatest, dogwood accumulated small amounts of glucose, quinic acid and Mg2+, offsetting a decline in nitrate concentration. As the mild drought continued and tree growth slowed, there was a significant accumulation of sucrose in dogwood in the dry treatment in June, and a trend toward increased K+. In overstory chestnut oak in the dry treatment over the same period, there were significant accumulations of fructose, glucose and K+, and a trend toward increased quinic acid accumulation. Sucrose did not become a key osmotically active compound in chestnut oak until August 1994. In 1995, with the exception of understory chestnut oak, there was no accumulation of K+ in either species. During the severe drought of 1995, monosaccharides, particularly glucose and fructose, accounted for most of the osmotic adjustment in both species. Among solutes, glucose constituted the largest accumulation in dogwood in the dry treatment in August 1995, followed by fructose and sucrose. There was only a moderate increase in solutes in chestnut oak trees in 1995, with fructose and glucose constituting over 50% of the predicted solute accumulation in July. Both species accumulated a wider array of solutes during the dry year than during the wet year, but treatment differences in solute accumulation in chestnut oak were partially limited by drought. The greater dehydration tolerance of chestnut oak than dogwood was evident in the higher baseline concentrations of organic solutes and the greater array of solutes accumulated in response to drought.
Adaptation, Physiological↗