Modes of union and interaction between parasite and host in the Loranthaceae. II. Phoradendreae

1957 ◽  
Vol 146 (924) ◽  
pp. 320-338 ◽  
Keyword(s):  
North America ◽  
Vascular System ◽  
Lower Side ◽  
Large Genus ◽  
Large Primary ◽  
Stimulation Of

The large genus Phoradendron includes not only species like those of North America already described and Ph. fanshawei from Trinidad, with cortical strands and sinkers comparable especially with those of Viscum capense , but also others with very different modes of attachment. Some have much enlarged primary haustoria, with subordinate cortical strands and sinkers ( Phoradendron trinervium on some hosts) or without them ( Ph. hartii, Ph. flavens ). Ph. trinervium on Calophyllum lucidum , in contrast with its behaviour on other hosts, forms no major wedge but the cortical strands show an exaggerated development with anastomosis of the strands and the formation of numerous sinkers. In Phoradendron crassifolium and Ph. tetrapteron the haustorium simply spreads against the host wood to form a saddle-like attachment. In Ph. perrottetii also the haustorium spreads against the host wood, occasionally girdling it completely, forming downward branches, sometimes twenty or more, which run parallel and in their older parts fuse. Dendrophthora inaequidentata forms a very large primary haustorium, with slender cortical strands. The growth of the haustorium in width is accompanied by conspicuous hypertrophy of host wood on the lower side of it, the vessels and other elements of which abut on the haustorium, linking up with the parasite vascular system and without continuity with host wood above the haustorium. Tangential enlargement of the haustorium with stimulation of the adjoining cambium and annexation of the wood it forms occurs also though less conspicuously in some species of Phoradendron , particularly Phoradendron trinervium (on Rollinia mucosa ) and Ph. flavens .

Adrenergic Stimulation of Regional Plasminogen Activator Release in Rabbits

1992 ◽  
Vol 68 (05) ◽  
pp. 545-549 ◽  
Author(s):  
W L Chandler ◽  
S C Loo ◽  
D Mornin
Keyword(s):  
Lower Extremity ◽  
Plasminogen Activator ◽  
Beta Blocker ◽  
Time Course ◽  
Vascular System ◽  
Adrenergic Stimulation ◽  
Epinephrine Administration ◽  
Adrenergic Antagonist ◽  
Vascular Beds ◽  
Stimulation Of

SummaryThe purpose of this study was to determine whether different regions of the rabbit vascular system show variations in the rate of plasminogen activator (PA) secretion. To start, we evaluated the time course, dose response and adrenergic specificity of PA release. Infusion of 1 µg/kg of epinephrine stimulated a 116 ± 60% (SD) increase in PA activity that peaked 30 to 60 s after epinephrine administration. Infusion of 1 µg/kg of norepinephrine, isoproterenol and phenylephrine had no effect on PA activity. Pretreatment with phentolamine, an alpha adrenergic antagonist, blocked the release of PA by epinephrine while pretreatment with the beta blocker propranolol had no effect. This suggests that PA release in the rabbit was mediated by some form of alpha receptor.Significant arterio-venous differences in basal PA activity were found across the pulmonary and splanchnic vascular beds but not the lower extremity/pelvic bed. After stimulation with epinephrine, PA activity increased 46% across the splanchnic bed while no change was seen across the lower extremity/pelvic bed. We conclude that several vascular beds contribute to circulating PA activity in the rabbit, and that these beds secrete PA at different rates under both basal and stimulated conditions.

Alloxan, but not streptozotocin, increases blood perfusion of pancreatic islets in rats

1992 ◽  
Vol 263 (1) ◽  
pp. E57-E63 ◽  
Author(s):  
L. Jansson ◽  
S. Sandler
Keyword(s):  
Blood Flow ◽  
Superoxide Dismutase ◽  
Vascular System ◽  
Flow Distribution ◽  
Blood Perfusion ◽  
Perfused Pancreas ◽  
Pancreatic Blood Flow ◽  
Acute Effects ◽  
Adult Rats ◽  
Stimulation Of

It has recently been shown that selective B-cell toxins alloxan and streptozotocin (STZ) possess marked effects also on the vascular system. To evaluate to what extent changes in blood perfusion of islets induced by alloxan or STZ could be of importance for diabetogenic action of these compounds, we first investigated acute effects of alloxan (75 mg/kg body wt iv) and STZ (40 mg/kg body wt iv) on both whole pancreatic blood flow (PBF) and islet blood flow (IBF) in adult rats. Alloxan caused a marked increase in IBF, which was most pronounced 3 min after administration and remained for 30 min. PBF, however, was decreased 3 min after alloxan administration but was similar to that of control animals from 10 min and onward. These two opposite effects on IBF and PBF caused the fraction of whole PBF diverted through islets to increase from approximately 10 to 50%. Pretreatment with glucose (2 g/kg body wt iv), indomethacin (3.5 mg/kg body wt iv), dimethyl sulfoxide (10 ml/kg body wt ip of a 33% solution), superoxide dismutase (SOD, 1,000 kU/kg body wt iv), NG-methyl-L-arginine (30 mg/kg body wt iv), theophylline (7 mg/kg body wt iv), or terbutaline (1 mg/kg body wt iv) failed to affect stimulation of IBF by alloxan observed at 3 min. SOD was found to exert a marked stimulation of IBF both when given alone and together with alloxan. Alloxan increased IBF and decreased PBF also in a syngeneic pancreaticoduodenal graft in rats but did not affect flow distribution in a perfused pancreas-duodenum preparation.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals eNOS function is developmentally regulated: uncoupling of eNOS occurs postnatally

2006 ◽  
Vol 290 (2) ◽  
pp. L232-L241 ◽  
Author(s):  
Eugenia Mata-Greenwood ◽  
Chrystal Jenkins ◽  
Kathryn N. Farrow ◽  
G. Ganesh Konduri ◽  
James A. Russell ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Soluble Guanylate Cyclase ◽  
Vascular System ◽  
Oxidase Inhibitor ◽  
Superoxide Production ◽  
No Production ◽  
Oxygen Species ◽  
Laminar Shear Stress ◽  
A 23187 ◽  
Stimulation Of

At birth, the transition to gas breathing requires the function of endothelial vasoactive agents. We investigated the function of endothelial nitric oxide synthase (eNOS) in pulmonary artery (PA) vessels and endothelial cells isolated from fetal and young (4-wk) sheep. We found greater relaxations to the NOS activator A-23187 in 4-wk-old compared with fetal vessels and that the NOS inhibitor nitro-l-arginine blocked relaxations in both groups. Relaxations in 4-wk vessels were not blocked by an inhibitor of soluble guanylate cyclase, 1H-[1,2,4]oxadiazolo-[4,3-a]quinoxalin-1-one, but were partially blocked by catalase. We therefore hypothesized that activation of eNOS produced reactive oxygen species in 4-wk but not fetal PA. To address this question, we studied NO and superoxide production by endothelial cells at baseline and following NOS stimulation with A-23187, VEGF, and laminar shear stress. Stimulation of NOS induced phosphorylation at serine 1177, and this event correlated with an increase in NO production in both ages. Upon stimulation of eNOS, fetal PA endothelial cells (PAEC) produced only NO. In contrast 4-wk-old PAEC produced superoxide in addition to NO. Superoxide production was blocked by l-NAME but not by apocynin (an NADPH oxidase inhibitor). l-Arginine increased NO production in both cell types but did not block superoxide production. Heat shock protein 90/eNOS association increased upon stimulation and did not change with developmental age. Cellular levels of total and reduced biopterin were higher in fetal vs. 4-wk cells. Sepiapterin [a tetrahydrobiopterin (BH4) precursor] increased basal and stimulated NO levels and completely blocked superoxide production. We conclude that the normal function of eNOS becomes uncoupled after birth, leading to a developmental adaptation of the pulmonary vascular system to produce oxygen species other than NO. We speculate this may be related to cellular production and/or maintenance of BH4 levels.

Silene alba and S. dioica in North America and the generic delimitation of Lychnis, Melandrium, and Silene (Caryophyllaceae)

1978 ◽  
Vol 56 (3) ◽  
pp. 297-308 ◽  
Author(s):  
J. McNeill
Keyword(s):  
North America ◽  
North American ◽  
Generic Delimitation ◽  
The North ◽  
Numerical Studies ◽  
Silene Alba ◽  
Melandrium Album ◽  
Limited Applicability ◽  
Large Genus ◽  
Genus Silene

Evidence is presented from numerical studies of herbarium and cultivated specimens and from observations on time of flowering that North American weed populations of white cockle are referable to the European Silene alba (≡ Lychnis alba ≡ Melandrium album) and are not, as has been suggested, the products of hybridization between that species and S. dioica. The present status and distribution in North America of S. alba, S. dioica, and the hybrids between them are described. Evidence for different generic circumscriptions of Silene, Lychnis, and Melandrium is analysed and the limited applicability of the capsule dehiscence character is demonstrated. Recent treatments that accept Lychnis in a narrow sense and assign most of the North American species of the group to a large genus Silene are accepted pending further study. Two new subspecific combinations (S. uralensis subsp. attenuata (Farr) McNeill and S. uralensis subsp. montana (S. Watson) McNeill) are proposed.

scholarly journals STUDIES ON THE STIMULATION OF CATALPA BIGNONIOIDES WALT. SEED GERMINATION

2021 ◽  
Vol 10 (20) ◽  
pp. 172-178
Author(s):  
Daniela-Sabina Poșta ◽  
Sándor Rózsa ◽  
Tincuța-Marta Gocan
Keyword(s):  
North America ◽  
Seed Germination ◽  
Exotic Species ◽  
Humid Climate ◽  
Methods And Techniques ◽  
Temperate Soils ◽  
Individual Trees ◽  
Stimulation Of ◽  
Compact Shape

Catalpa is a tree with an attractive ornamental value and compact shape. Catalpa bignonioides Walt., is a tree with heights of up to 35 meters and a large trunk. It is an exotic species in North America areal. It grows well in a warm and humid climate, on alluvial, fertile, deep, temperate soils. It has a light temperament, withstands winter frosts well, but is sensitive to late frosts. The degree of germination varies both between species and within them. Within batches of seeds of the same species varies depending on the origin, year of harvest and individual trees. There are different methods and techniques for overcoming drowsiness depending on the seeds. Various pre-treatments are used such as scarification and hot and cold aeration to stimulate the embryo. The paper presents the stimulation of seed germination at catalpa, using different concentrations of Nitragin: 0.1%, 0.3%, 0.5%, 0.7%, 0.9% and following the seed germination interval.

Long-term electrical stimulation of rabbit skeletal muscle increases growth of paired arteries and veins

1995 ◽  
Vol 269 (2) ◽  
pp. H717-H724 ◽  
Author(s):  
T. H. Adair ◽  
J. Hang ◽  
M. L. Wells ◽  
F. D. Magee ◽  
J. P. Montani
Keyword(s):  
Skeletal Muscle ◽  
Vascular System ◽  
Common Peroneal Nerve ◽  
Numerical Density ◽  
Muscle Stimulation ◽  
Longus Muscle ◽  
The Right ◽  
Arteries And Veins ◽  
Stimulation Of

We tested whether chronic stimulation of skeletal muscle can increase the growth of paired arteries and veins in rabbit extensor digitorum longus muscle (EDL). The right EDL of female New Zealand White rabbits was stimulated via the common peroneal nerve at 10 Hz using 300 microseconds square waves at 3-4 V. Two-hour periods of stimulation was alternated with 4-h periods of rest, 7 days/wk for approximately 60 days. The left EDL served as control. The hindlimb vascular system was maximally dilated and perfuse-fixed with 3% glutaraldehyde and 2% paraformaldehyde at arterial and venous pressures of 80-100 and 15-20 mmHg, respectively. Muscles were postfixed in OsO4 and embedded in EPOX 812 resin. One millimeter-thick transverse sections were cut at uniform locations through the entire breadth of the muscle and analyzed using videomicroscopy along with computerized morphometric and stereological techniques. All paired arteries and veins on each full muscle section were analyzed. Chronic muscle stimulation caused the wall volume of paired arteries and veins to increase by an average of approximately twofold and the lumen volume to increase by an average of approximately threefold compared with the contralateral muscles. The wall-to-lumen area ratio of the arteries and veins was not affected. Muscle stimulation also caused the numerical density of arteries having a diameter > 100 microns to increase by approximately fourfold and the density of veins having a perimeter > 500 microns to increase by approximately 10-fold.(ABSTRACT TRUNCATED AT 250 WORDS)

A taxonomic revision of Caloplaca herbidella and C. furfuracea

2009 ◽  
Vol 41 (5) ◽  
pp. 465-480 ◽  
Author(s):  
Ulf ARUP ◽  
Elin ÅKELIUS
Keyword(s):  
North America ◽  
Molecular Analysis ◽  
Taxonomic Revision ◽  
Strict Sense ◽  
Separate Species ◽  
Distribution Maps ◽  
Morphometric Methods ◽  
Large Genus ◽  
Grey Colour ◽  
New Distribution

AbstractCaloplaca herbidella (Hue) H. Magn. and C. furfuracea H. Magn. are two isidiate, epiphytic species in the large genus Caloplaca. Caloplaca herbidella in a strict sense is normally grey and fertile with thick, somewhat coralloid isidia, but orange, sterile forms with thin isidia also occur. Caloplaca furfuracea is superficially similar morphologically to C. herbidella s. str. but has thinner, more granular isidia and generally a darker grey colour. Doubts have been raised as to whether C. furfuracea should be acknowledged as a proper species or incorporated in C. herbidella. Using morphometric methods and molecular analysis of the nrITS DNA gene we show that C. herbidella and C. furfuracea are two clearly separated species. Furthermore, the mainly sterile, orange form of C. herbidella can be regarded as a separate species that is here described as C. coralliza Arup & Åkelius. All three species are described in detail, including photographs and notes on their ecology. Finally, new distribution maps for Europe show that C. herbidella and C. coralliza are widespread in Europe, but the latter is probably less common than the former. Caloplaca furfuracea is clearly very rare in Europe with only few collections from Switzerland and Sweden, but seems to be more common in North America.

XXXIII.—The Blood Vascular System of the Spiny Dogfish, Squalus acanthias Linné, and Squalus sucklii Gill

1928 ◽  
Vol 55 (3) ◽  
pp. 823-890 ◽  
Author(s):  
Charles H. O'Donoghue ◽  
Eileen (Bulman) Abbott
Keyword(s):  
North America ◽  
Vascular System ◽  
Individual Preference ◽  
Squalus Acanthias ◽  
The Other ◽  
Spiny Dogfish ◽  
Considerable Confusion ◽  
Satisfactory Account ◽  
Future Work ◽  
Made In

The following investigation was commenced, in the first place, to provide information for class use, for, in spite of the fact that thousands of specimens of Squalus acanthias and S. sucklii are used every year in North America, there appears to be no satisfactory account of the blood vascular system of either species available. As the work proceeded, various problems arose which necessitated references to the conditions in other species and the preparation of more detailed dissections than are usually made in class work. It is well known that there is considerable confusion in the nomenclature employed by different authors for even some of the main vessels, and it was soon evident that this is not merely individual preference but, in part, due to a more fundamental lack of agreement as to the precise morphological significance of the vessels themselves. More recent embryological investigations by other workers have, we consider, given a key to the solution of the most important of these problems and have shown that, in so far as the blood-vessels are concerned, the Elasmobranchs lie closer to the other gnathostomatous vertebrates than is generally recognised, and indeed furnish a primitive and generalised type. The time seemed ripe, therefore, to provide a connected account of the vascular system in an Elasmobranch, viewing it in the light of the researches just referred to, and of what is known of the distribution of the various vessels in the sub-class in general. It was hoped that this would provide an epitome that would serve as a basis for future work in the sub-class, and also for comparison with the conditions in higher vertebrates.

ACTIVITY OF THE VASCULAR CAMBIUM IN RELATION TO WOUNDING IN THE BALSAM POPLAR, POPULUS BALSAMIFERA L.

1937 ◽  
Vol 15c (1) ◽  
pp. 7-31 ◽  
Author(s):  
A. B. Brown
Keyword(s):  
Cambial Activity ◽  
Living Cells ◽  
Vascular Cambium ◽  
Limiting Factor ◽  
Populus Balsamifera ◽  
Lower Side ◽  
Balsam Poplar ◽  
Complete Ring ◽  
Type Of Behavior ◽  
Stimulation Of

An investigation of the response of the vascular cambium to wounding in leader shoots of the balsam poplar, Populus balsamifera L., was carried out in the laboratory during the winter months, at which time observations on local wound cambial activity, distinct and apart from normal cambial activity, can be obtained. It was found, in disbudded units, that the greater the amount of living bark distal to a wound, the greater is the development of local cambial activity in relation to the wound. Local wound cambial activity is further promoted by the presence of developing buds and leaves distal to the wound, and the effect can be observed before the basipetal gradient of normal cambial activity emanating from the developing extension growth has reached the wound. Cambial activity in relation to wounding responds to gravity in the same way as normal cambial activity. In horizontally placed leader shoots, cambial activity is greater in relation to a wound on the upper side of the shoot than to a similar wound directly opposite on the lower side. On the basis of these results, it is suggested that a hormone, present in the living bark and also produced by developing buds and leaves, is involved in local wound cambial activity. In all probability this hormone is identical with that which promotes normal cambial activity.It is also suggested that a wound substance, capable of promoting by itself cell division only, is involved in local wound cambial activity. The amount of this wound substance produced is apparently proportional to the extent of dying of the cells of the bark subsequent to wounding. From the lower edge of a complete ring, a very feeble basipetal gradient of cambial activity arises, in which differentiation to form vessels and fibres does not occur, although a few tracheids may be found. This type of behavior has not hitherto been reported, and is interpreted as the result of stimulation of the cambial layers by the wound substance alone. Local cambial activity above a complete ring and in relation to bridged wounds, involves differentiation of more or less typical vessels and fibres, and is interpreted as the result of interaction between the wound substance and the cambial hormone traveling basipetally in the living cells of the bark. The absence or feebler development of cambial activity at certain points in relation to bridged wounds, in contrast to greater development at other points where presumably the concentration of cambial hormone must be less, is interpreted as the result of lack of wound substance or low concentration of it acting as a limiting factor.

A monograph of Dolerotheca Halle, and related complex permineralised medullosan pollen organs

1986 ◽  
Vol 77 (1) ◽  
pp. 47-79 ◽  
Author(s):  
Gar W. Rothwell ◽  
Donald A. Eggert
Keyword(s):  
North America ◽  
Internal Structure ◽  
Vascular System ◽  
Vascular Bundles ◽  
Ground Tissue ◽  
Type Specimens ◽  
Histological Features ◽  
Folding Pattern ◽  
Distal Surface ◽  
Complex Forms

ABSTRACTNumerous permineralised, complex medullosan pollen organs are described from Middle and Upper Pennsylvanian sediments of North America. Together with a reinvestigation of type specimens for the previously described species, these provide the basis for fully characterising internal structure and external morphology, and for recognising structural homologies among all medullosan synangia. All medullosan pollen organs, simple and complex, can be interpreted as consisting of sporangial tubes that are embedded in parenchymatous and sclerenchymatous ground tissue, and that have vascular bundles within the parenchymatous tissue. The sporangial tubes are arranged in a single series, usually a ring, with parenchymatous ground tissues and vascular bundles to the outside of the ring and sclerenchymatous ground tissue to the inside of the ring. In the larger, complex forms the ring is plicately folded and there may be a centrally-placed hollow in the distal surface. Differences in morphology, in the folding pattern of the rings, in the structure (or absence) of a distal hollow, and in architecture of the major vascular system are employed to delimit genera. Size and shape of the organ, histological features, numbers of sporangia, and presence or absence of lacunae are used to delineate species. Currently recognised genera are Dolerotheca Halle, Sullitheca Stidd et al., Stewartiotheca Eggert and Rothwell, and Bernaultia gen. nov.

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